CN116724687A - Piezoelectric single crystal including internal electric field, method of manufacturing the same, and piezoelectric and dielectric application member using the same - Google Patents
Piezoelectric single crystal including internal electric field, method of manufacturing the same, and piezoelectric and dielectric application member using the same Download PDFInfo
- Publication number
- CN116724687A CN116724687A CN202180082485.1A CN202180082485A CN116724687A CN 116724687 A CN116724687 A CN 116724687A CN 202180082485 A CN202180082485 A CN 202180082485A CN 116724687 A CN116724687 A CN 116724687A
- Authority
- CN
- China
- Prior art keywords
- single crystal
- piezoelectric
- ltoreq
- electric field
- piezoelectric single
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000013078 crystal Substances 0.000 title claims abstract description 408
- 230000005684 electric field Effects 0.000 title claims abstract description 183
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 41
- 239000000203 mixture Substances 0.000 claims abstract description 132
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 83
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 83
- 239000001301 oxygen Substances 0.000 claims abstract description 83
- 238000010438 heat treatment Methods 0.000 claims abstract description 78
- 238000000034 method Methods 0.000 claims description 85
- 239000000126 substance Substances 0.000 claims description 63
- 230000008569 process Effects 0.000 claims description 52
- 239000000843 powder Substances 0.000 claims description 35
- 230000007704 transition Effects 0.000 claims description 33
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 claims description 23
- 230000002159 abnormal effect Effects 0.000 claims description 22
- 230000000704 physical effect Effects 0.000 claims description 20
- 238000005245 sintering Methods 0.000 claims description 20
- 239000011159 matrix material Substances 0.000 claims description 14
- 229910052684 Cerium Inorganic materials 0.000 claims description 7
- 229910052765 Lutetium Inorganic materials 0.000 claims description 7
- 229910052735 hafnium Inorganic materials 0.000 claims description 7
- 229910052758 niobium Inorganic materials 0.000 claims description 7
- 229910052721 tungsten Inorganic materials 0.000 claims description 7
- 229910052725 zinc Inorganic materials 0.000 claims description 7
- 229910052726 zirconium Inorganic materials 0.000 claims description 7
- 229910052745 lead Inorganic materials 0.000 claims description 6
- 229920000642 polymer Polymers 0.000 claims description 5
- 239000003990 capacitor Substances 0.000 claims description 4
- 230000008878 coupling Effects 0.000 claims description 4
- 238000010168 coupling process Methods 0.000 claims description 4
- 238000005859 coupling reaction Methods 0.000 claims description 4
- 230000003247 decreasing effect Effects 0.000 claims description 2
- 150000002500 ions Chemical class 0.000 abstract description 31
- 241001591024 Samea Species 0.000 abstract 1
- 239000012071 phase Substances 0.000 description 107
- 239000012298 atmosphere Substances 0.000 description 40
- 230000001965 increasing effect Effects 0.000 description 31
- 230000007423 decrease Effects 0.000 description 19
- 238000002109 crystal growth method Methods 0.000 description 17
- 239000007790 solid phase Substances 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 12
- 239000000370 acceptor Substances 0.000 description 9
- 238000001354 calcination Methods 0.000 description 9
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 8
- 230000008859 change Effects 0.000 description 8
- 238000011156 evaluation Methods 0.000 description 8
- 238000005728 strengthening Methods 0.000 description 8
- 238000007716 flux method Methods 0.000 description 7
- 238000002844 melting Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 230000001747 exhibiting effect Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000002156 mixing Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 239000007791 liquid phase Substances 0.000 description 5
- 230000001105 regulatory effect Effects 0.000 description 5
- 239000000919 ceramic Substances 0.000 description 4
- 238000010309 melting process Methods 0.000 description 4
- 239000011812 mixed powder Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- JMAHHHVEVBOCPE-UHFFFAOYSA-N [Fe].[Nb] Chemical compound [Fe].[Nb] JMAHHHVEVBOCPE-UHFFFAOYSA-N 0.000 description 2
- 238000000498 ball milling Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000002706 hydrostatic effect Effects 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 230000028161 membrane depolarization Effects 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 229910052706 scandium Inorganic materials 0.000 description 1
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The present invention relates to a piezoelectric single crystal comprising an internal electric field, a method for producing the same, and piezoelectric and dielectric applications using the sameA component. The piezoelectric single crystal of the present invention has a perovskite crystal structure ([ A)][B]O 3 ) Wherein control [ A ]]Site ion, [ B ]]Site ion and [ O ]]The variation of the respective compositions of the bit ions and the partial pressure of oxygen during the heat treatment in the manufacturing process, thereby maintaining the high dielectric constant and piezoelectric constant inherent in the piezoelectric single crystal while satisfying the high internal bias electric field (E I ) Characteristics, therefore, piezoelectric application parts and dielectric application parts using piezoelectric single crystals having excellent characteristics can be used under a wide temperature range and operating voltage conditions.
Description
Technical Field
The present invention relates to a piezoelectric single crystal including an internal bias electric field, a method of manufacturing the same, and piezoelectric and dielectric application members using the same, and more particularly, to a novel piezoelectric single crystal having a perovskite crystal structure through a perovskite crystal structure ([ a) ][B]O 3 ) [ A ] of (2)]Site ion, [ B ]]Site ion and [ O ]]The variation of the respective compositions of the bit ions and the improvement of the piezoelectric properties of the single crystal by controlling the oxygen partial pressure at the time of heat treatment in terms of manufacturing process satisfy the properties EI of the internal bias electric field of 0.5 to 3.0kV/cm or more, which is critical for the high coercive electric field and the electrical stability of the piezoelectric single crystal, while maintaining the inherent high dielectric constant and high piezoelectric charge constant of the piezoelectric single crystal.
Background
Due to the perovskite crystal structure ([ A)][B]O 3 ) Dielectric constant K exhibited by a piezoelectric single crystal of (C) 3 T And piezoelectric charge constant d 33 And k 33 The application of piezoelectric single crystals to high performance components such as piezoelectric actuators, ultrasonic transducers, piezoelectric sensors, dielectric capacitors, etc., is expected to be incredibly higher than those shown by the existing piezoelectric polycrystalline materials, and practical applications will also introduce them into substrates for various thin film elements.
Examples of piezoelectric single crystals having a perovskite crystal structure developed so far include PMN-PT (Pb (Mg) 1/ 3 Nb 2/3 )O 3 -PbTiO 3 )、PZN-PT(Pb(Zn 1/3 Nb 2/3 )O 3 -PbTiO 3 )、PInN-PT(Pb(In 1/2 Nb 1/2 )O 3 -PbTiO 3 )、PYbN-PT(Pb(Yb 1/2 Nb 1/2 )O 3 -PbTiO 3 )、PSN-PT(Pb(Sc 1/2 Nb 1/2 )O 3 -PbTiO 3 )、PMN-PInN-PT、PMN-PYbN-PT、BiScO 3 -PbTiO 3 (BS-PT), and the like. Since these single crystals exhibit uniform melting behavior when melted, they are generally manufactured by a flux method (flux method), a Bridgman method, or the like, which is an existing single crystal growth method.
However, although the PMN-PT and PZN-PT piezoelectric single crystals developed previously have a high dielectric and piezoelectric property (K 3 T >4,000，d 33 >1,400pC/N，k 33 >0.85 Due to, for example, a low phase transition temperature T) C And T RT Low coercive electric field E C Defects such as brittleness and the like are quite limited in application.
In general, it has been known that a piezoelectric single crystal having a perovskite crystal structure exhibits the highest dielectric and piezoelectric characteristics with respect to composition from adjacent boundaries in a quasi-type phase boundary (i.e., MPB) between rhombohedral and tetragonal phases.
However, since a piezoelectric single crystal having a perovskite crystal structure generally exhibits the most excellent dielectric and piezoelectric characteristics when it has a rhombohedral phase, practical application of the rhombohedral phase piezoelectric single crystal is most actively performed, but since the rhombohedral phase piezoelectric single crystal has only a phase transition temperature T between the rhombohedral phase and the tetragonal phase RT They are stable only at the phase transition temperature T RT The following (i.e., highest temperature at which rhombohedral phase stabilizes) was used. Thus, at the phase transition temperature T RT At a lower level, the operable temperature of the rhombohedral piezoelectric single crystal becomes low, and the temperature required for manufacturing the component to which the piezoelectric single crystal is applied and the operable temperature of the applied component are also limited to the phase transition temperature T RT The following is given.
In addition, at the phase transition temperature T C And T RT And coercive electric field E C At lower levels, piezoelectric single crystals are prone to depolarization under machining, stress, heat generation and driving voltages, and loss of excellent dielectric and piezoelectric properties occurs. Thus, the phase transition temperature T is shown C And T RT Coercive electric field E C Lower piezoelectric single crystals are limited in terms of manufacturing conditions, operable temperature conditions, driving voltage conditions, etc. of components to which the single crystals are applied. In the case of PMN-PT single crystals, curie temperature T C Phase transition temperature T RT And coercive electric field E C Generally respectively satisfy T C <150℃、T RT <80 ℃ and E C <2.5kV/cm, and in the case of PZN-PT single crystals, curie temperature T C Phase transition temperature T RT And coercive electric field E C Generally respectively satisfy T C <170℃、T RT <100 ℃ and E C <3.5kV/cm. In addition, since dielectric and piezoelectric components manufactured using these piezoelectric single crystals are also limited in manufacturing conditions, operable temperature ranges, operating voltage conditions, and the like, this has been an obstacle in development and practical use of components to which piezoelectric single crystals are applied.
To overcome the weakness of piezoelectric single crystals, single crystals of new compositions such as PInN-PT, PSN-PT, BS-PT, etc. have also been developed, and various single crystal compositions in mixed forms such as PMN-PInN-PT, PMN-BS-PT, etc. have also been studied.
However, in the case of these single crystals, there are problems In that the dielectric constant, the piezoelectric charge constant, the phase transition temperature, the coercive electric field, the mechanical characteristics, and the like cannot be improved at the same time, and In the case of a piezoelectric single crystal containing an expensive element such as Sc, in, and the like as a main component, there is a problem In that the high production cost of the single crystal is an obstacle to practical use of the single crystal.
The reason why the piezoelectric single crystal having a perovskite crystal structure containing PMN-PT developed so far exhibits a low phase transition temperature can be roughly divided into three points: first, the phase transition temperature of a relaxation agent (PMN or PZN, etc.) as a main component together with PT is low.
Second, since the quasi-homotype phase boundary (MPB) at the boundary formed by the tetragonal phase and the rhombohedral phase is smoothly inclined rather than perpendicular to the temperature axis, it is necessary to lower the Curie temperature T C To increase the phase transition temperature T of the rhombohedral phase and the tetragonal phase RT Therefore, it is difficult to raise the Curie temperature T at the same time C Phase transition temperature T of rhombohedral phase and tetragonal phase RT 。
Third, even if the phase transition temperature is relatively high (PYbN, PInN or BiScO) 3 Etc.) into PMN-PT or the like, the phase transition temperature does not simply increase in proportion to the composition, or the problem of deterioration of dielectric and piezoelectric characteristics arises.
In addition, the single crystal of the relaxant-PT series provided in non-patent document 1 is produced by a flux method, a bridgman method, or the like as a conventional single crystal growth method, it is difficult to produce a large single crystal having a uniform composition due to reasons related to the production process of the single crystal, and the single crystal has not been successfully commercialized due to high production costs and difficulty in mass production.
In addition, although piezoelectric single crystals generally exhibit a high piezoelectric charge constant (d) 33 Not less than 2,000 and not more than 4,000 pC/N), but due to the low coercive electric field (E C And 2 kV/cm) is liable to be depolarized, the piezoelectric single crystal is limited in practical use due to low electrical stability. Therefore, although a method of increasing the coercive electric field of the piezoelectric single crystal has been proposed, it has been pointed out that the increase in coercive electric field still lacks an effect due to the problem caused by the decrease in piezoelectric characteristics.
Accordingly, as a result of the efforts made by the present inventors to improve the conventional problems, the present invention has been completed in the following manner: a method of maintaining high-voltage electric characteristics and electrical stability of a piezoelectric single crystal at the same time by appropriately increasing a coercive electric field and an internal bias electric field, and controlling a crystal structure (([ A ]) with respect to a perovskite type is devised][B]O 3 ) [ A ] of (2)]Positioning and separating Seed, [ B ]]Site ion and [ O ]]Variation of respective compositions of the bit ions and partial pressure of oxygen at the time of heat treatment in terms of manufacturing process, thereby confirming that physical properties satisfy a high internal bias electric field E necessary for electrical stability of the piezoelectric single crystal I While maintaining the high dielectric constant and high piezoelectric charge constant inherent in the piezoelectric single crystal.
Patent document 1: korean patent No. 0564092 (formal publication of 27 th month and 3 th 2006)
Patent document 2: korean patent No. 0743614 (formal publication of 2007, 7, 30)
Non-patent document 1: IEEE Transactions on Ultrasonics Ferroelectric, and Frequency Control, vol.44, no.5,1997, pp.1140-1147.
Disclosure of Invention
Technical problem
It is an object of the present invention to provide a piezoelectric single crystal comprising an internal bias electric field.
Another object of the present invention is to provide a method for producing a piezoelectric single crystal.
It is another object of the present invention to provide a piezoelectric component or a dielectric component to which the piezoelectric single crystal is applied.
Solution to the problem
To achieve the above object, the present invention provides a composition having a perovskite structure ([ A ]][B]O 3 ) Is satisfied with the following physical properties: (1) Dielectric constant K 3 T Is 4000 or more; (2) Piezoelectric charge constant d 33 1400pC/N or more; (3) Coercive electric field E C 3.5kV/cm or more; (4) an internal bias electric field E I Is more than 0.5 kV/cm.
More preferably, the present invention can provide a composition having a perovskite structure ([ A ]][B]O 3 ) Is satisfied with the following physical properties: (1) a dielectric constant of 5000 or more; (2) Piezoelectric charge constant d 33 1500pC/N or more; (3) Coercive electric field E C Is more than 4.0 kV/cm; (4) an internal bias electric field E I Is more than 1.0 kV/cm.
Has a perovskite structure ([ A)][B]O 3 ) The piezoelectric single crystal of (2) can be configured in the following manner: control [ A ]]Site ion, [ B ]]Site ion and [ O ]]The respective compositions of the bit ions are such that the coercive electric field and the internal bias electric field are increased, thereby maintaining the electrical stability and high-voltage electrical characteristics of the piezoelectric single crystal.
Therefore, according to the structure having perovskite type ([ A)][B]O 3 ) The following piezoelectric single crystal having a perovskite structure ([ a ] may be provided][B]O 3 ) A piezoelectric single crystal represented by the composition formula of chemical formula 1:
chemical formula 1
[A 1-(a+1.5b )B a C b ][(MN) 1-x-y (L) y Ti x ]O 3
In the formula, A represents Pb or Ba,
b represents at least one or more elements selected from the group consisting of Ba, ca, co, fe, ni, sn and Sr,
c represents one or more elements selected from the group consisting of Co, fe, bi, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb and Lu,
L represents a single form composed of one selected from Zr or Hf, or a mixed form thereof,
m represents at least one or more elements selected from the group consisting of Ce, co, fe, in, mg, mn, ni, sc, yb and Zn,
n represents at least one or more elements selected from the group consisting of Nb, sb, ta and W, and
a. b, x and y represent 0<a.ltoreq.0.10, 0<b.ltoreq.0.05, 0.05.ltoreq.x.ltoreq.0.58 and 0.05.ltoreq.y.ltoreq.0.62, respectively.
In addition, the compound has a perovskite structure ([ A)][B]O 3 ) A piezoelectric single crystal represented by the composition formula of the following chemical formula 2 may be provided:
chemical formula 2
[A 1-(a+1.5b) B a C b ][(MN) 1-x-y (L) y Ti x ]O 3-z
In the case of the formula (I) described above,
a represents Pb or Ba, and the component A is represented,
b represents at least one or more elements selected from the group consisting of Ba, ca, co, fe, ni, sn and Sr,
c represents one or more elements selected from the group consisting of Co, fe, bi, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb and Lu,
l represents a single form composed of one selected from Zr or Hf, or a mixed form thereof,
m represents at least one or more elements selected from the group consisting of Ce, co, fe, in, mg, mn, ni, sc, yb and Zn,
n represents at least one or more elements selected from the group consisting of Nb, sb, ta and W, and
a. b, x, y and z represent 0<a.ltoreq.0.10, 0<b.ltoreq.0.05, 0.05.ltoreq.x.ltoreq.0.58, 0.05.ltoreq.y.ltoreq.0.62 and 0<z.ltoreq.0.02, respectively.
When L represents a mixed form, a piezoelectric single crystal represented by the following formula 3 or formula 4 may be provided:
chemical formula 3
[A 1-(a+1.5b) B a C b ][(MN) 1-x-y (Zr 1-w ,Hf w ) y Ti x ]O 3
Chemical formula 4
[A 1-(a+1.5b) B a C b ][(MN) 1-x-y (Zr 1-w ,Hf w ) y Ti x ]O 3-z ，
Wherein A, B, C, M and N are the same as those shown in chemical formula 1 or chemical formula 2, and a, b, x and y are also the same as those shown in chemical formula 1 or chemical formula 2, but w represents 0.01.ltoreq.w.ltoreq.0.20.
The piezoelectric single crystal represented by the composition formula of chemical formula 1 or chemical formula 2 of the present invention may be based on a composition satisfying 0.01.ltoreq.a.ltoreq.0.10 and 0.01.ltoreq.b.ltoreq.0.05, more preferably, satisfying a/b.ltoreq.2 of the formula.
The piezoelectric single crystal represented by the composition formula of chemical formula 1 or chemical formula 2 of the present invention may be based on a composition satisfying 0.10.ltoreq.x.ltoreq.0.58 and 0.10.ltoreq.y.ltoreq.0.62.
In the piezoelectric single crystal represented by the composition formula of chemical formula 1 or chemical formula 2 of the present invention, the porosity inside the single crystal may be preferably 0.5% by volume or more.
Further, the piezoelectric single crystal represented by the composition formula of chemical formula 1 or chemical formula 2 of the present invention may show that a composition gradient inside the single crystal is formed in the range of 0.2 to 0.5 mol%.
For the piezoelectric single crystal, the x and y may fall within 10mol% of the composition of the quasi-homotype phase boundary between the rhombohedral phase and the tetragonal phase, and more preferably, the x and y may fall within 5mol% of the composition of the quasi-homotype phase boundary between the rhombohedral phase and the tetragonal phase.
The piezoelectric single crystal may exhibit a curie temperature T C At the same time, the phase transition temperature T between the rhombohedral phase and the tetragonal phase is more than 180 DEG C RT Is above 100deg.C.
In addition, the piezoelectric single crystal can satisfy the longitudinal electromechanical coupling coefficient k 33 Is 0.85 or more and has a coercive electric field E C 3.5 to 12kV/cm.
The present invention can provide a method for producing a piezoelectric single crystal, comprising: step (a): reducing the number density of abnormal grains (i.e., the number of abnormal grains per unit area) by adjusting the average size of matrix grains having polycrystal grains constituting the composition of the piezoelectric single crystal; and (b) growing the abnormal crystal grains by heat-treating the polycrystal exhibiting a decrease in the number density of the abnormal crystal grains obtained through the step (a), wherein a powder molded article is obtained in such a manner that a powder based on the composition constituting the piezoelectric single crystal is calcined at a temperature of less than 800 to 900 ℃, and a first heat-treating process of sintering the powder molded article and a second heat-treating process required at the time of single crystal growth are performed.
According to the method for producing a piezoelectric single crystal, the piezoelectric single crystal has a perovskite crystal structure ([ A)][B]O 3 ) Piezoelectric single crystal of [ A ]]Site ion sum [ B ] ]The composition of each bit ion is controlled, the inherent high dielectric constant, high piezoelectric charge constant and high coercive electric field of the piezoelectric single crystal are maintained, and the induction can be sufficiently largeInternal bias electric field E not present in general PMN-PT single crystals I It is therefore possible to provide a novel piezoelectric single crystal having a large resistance to the external environment.
Further, the present invention can provide a piezoelectric body composed of a piezoelectric single crystal having excellent characteristics, or a piezoelectric body in which a piezoelectric single crystal and a polymer are mixed.
Further, a piezoelectric application member and a dielectric application member using the piezoelectric body may be provided.
An example of the piezoelectric application part and the dielectric application part may be applied to any one selected from the group consisting of an ultrasonic transducer, a piezoelectric actuator, a piezoelectric sensor, a dielectric capacitor, an electric field generating transducer, and an electric field vibration generating transducer.
Effects of the invention
The piezoelectric single crystal and the piezoelectric application part using the piezoelectric single crystal of the present invention have advantages that can be used for a wide temperature range and operating voltage conditions because they have the characteristic of a high internal bias electric field (EI. Gtoreq.0.5 to 3.0 kV/cm) which is critical to the electrical stability of the piezoelectric single crystal, and exhibit excellent physical properties: dielectric constant K 3 T A piezoelectric charge constant d of 4000 or more 33 A coercive electric field E of 1400pC/N or more C Is 3.5kV/cm or more.
In addition, the piezoelectric single crystal can be manufactured using a solid phase single crystal growth method suitable for single crystal mass production, and commercialization of the piezoelectric single crystal can be achieved by developing a single crystal composition that does not contain expensive raw materials.
Furthermore, the piezoelectric single crystal and the member using the piezoelectric single crystal of the present invention enable the piezoelectric and dielectric application member using the piezoelectric single crystal having excellent characteristics to be manufactured and used in a wide temperature range.
Drawings
FIG. 1 shows [ Pb ] according to a first exemplary embodiment of the invention 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 Piezoelectric single crystal of (a)，
FIG. 2 shows [ Pb ] according to the first exemplary embodiment of the present invention 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.01; y=0.05; piezoelectric single crystal [ single crystal growth atmosphere (air) of examples 1 to 3); because Mn is added to be black]，
FIG. 3 shows [ Pb ] according to the first exemplary embodiment of the present invention 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.01; y=0.05; piezoelectric single crystal [ single crystal growth atmosphere (N2-H2) of examples 1-3); because Mn is added to be black]，
FIG. 4 shows [ Pb ] according to the first exemplary embodiment of the present invention 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 ( x=0.01; y=0.05; examples 1 to 3) piezoelectric single crystals [ Single Crystal growth atmosphere (air) ) ]A map of the associated polarized electric field,
FIG. 5 shows a polarization-electric field diagram related to a general PMN-30PT piezoelectric single crystal [ single crystal growth atmosphere (air) ] manufactured by a solid phase single crystal growth method,
FIG. 6 shows [ Pb ] according to the first exemplary embodiment of the present invention 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.01; y=0.05; examples 1 to 4) piezoelectric single crystal [ single crystal growth atmosphere (N 2 -H 2 )]A related polarization-electric field diagram,
FIG. 7 shows [ Pb ] according to the second exemplary embodiment of the present invention 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/ 3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (x=0.01; z=0.0; comparative example 5),
FIG. 8 shows [ Pb ] according to the second exemplary embodiment of the present invention 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/ 3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (x=0.01; z=0.005; example 3-3),
FIG. 9 shows [ Pb ] according to the second exemplary embodiment of the present invention 0.98 -1.5xSr 0.02 Sm x ][(Mg 1/ 3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (x=0.01; z=0.01; examples 3 to 4),
FIG. 10 is a view showing [ Pb ] in a piezoelectric single crystal according to a second exemplary embodiment of the invention 0.98- 1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (x=0.01; z=0.0, comparative example 6) and satisfies x=0.01; z=0.02 (examples 4 to 5).
Detailed Description
Hereinafter, the present invention is described in detail.
The invention provides a piezoelectric single crystal which maintains high-voltage electric characteristics in a manner of improving coercive electric field and internal bias electric field and maintains electric stability of the piezoelectric single crystal.
The present invention provides a material having a perovskite structure ([ A ] containing an internal bias electric field][B]O 3 ) Is satisfying the following physical properties: (1) Dielectric constant K 3 T Is 4000 or more; (2) Piezoelectric charge constant d 33 1400pC/N or more; (3) Coercive electric field E C 3.5kV/cm or more; (4) an internal bias electric field E I Is more than 0.5 kV/cm.
More preferably, the present invention provides a composition having a perovskite structure ([ A ]][B]O 3 ) Is satisfying the following physical properties:(1) Dielectric constant K 3 T More than 5000; (2) Piezoelectric charge constant d 33 1500pC/N or more; (3) Coercive electric field E C Is more than 4.0 kV/cm; (4) an internal bias electric field E I Is more than 1.0 kV/cm.
Specifically, the piezoelectric single crystal satisfies the following conditions: (1) Dielectric constant K 3 T 4000 to 15000; (2) Piezoelectric charge constant d 33 1400 to 6000pC/N; (3) Coercive electric field E C 3.5 to 12kV/cm; (4) an internal bias electric field E I From 0.5 to 3.0kV/cm.
In addition, the piezoelectric single crystal of the present invention is characterized in that the physical properties listed in (1) to (4) are maintained at a temperature of 20 to 80 ℃.
The values of the dielectric constant and the piezoelectric charge constant may be evaluated under the same temperature condition at normal temperature, and refer to the values of the dielectric constant and the piezoelectric charge constant evaluated at 30 ℃ unless the context of the present specification indicates otherwise.
Perovskite structure ([ A)][B]O 3 ) Piezoelectric single crystal display of (A), control [ A ]]Site ion, [ B ]]Site ion and [ O ]]The respective compositions of the bit ions increase the coercive electric field and the internal bias electric field, thereby maintaining the electrical stability and high-voltage electrical characteristics of the piezoelectric single crystal.
Accordingly, the present invention provides a composition represented by the following chemical formula 1 according to the first exemplary embodiment having a perovskite type structure ([ a)][B]O 3 ) Is a piezoelectric single crystal of (a):
chemical formula 1
[A 1-(a+1.5b )B a C b ][(MN) 1-x-y (L) y Ti x ]O 3
In the formula, A represents Pb or Ba,
b represents at least one or more elements selected from the group consisting of Ba, ca, co, fe, ni, sn and Sr,
c represents one or more elements selected from the group consisting of Co, fe, bi, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb and Lu,
l represents a single form composed of one selected from Zr or Hf, or a mixed form thereof,
m represents at least one or more elements selected from the group consisting of Ce, co, fe, in, mg, mn, ni, sc, yb and Zn,
n represents at least one or more elements selected from the group consisting of Nb, sb, ta and W, and
a. b, x and y represent 0<a.ltoreq.0.10, 0<b.ltoreq.0.05, 0.05.ltoreq.x.ltoreq.0.58 and 0.05.ltoreq.y.ltoreq.0.62, respectively.
Further, the present invention provides a composition formula represented by the following chemical formula 2 according to the second exemplary embodiment having a perovskite type structure ([ a ]][B]O 3 ) Is a piezoelectric single crystal of (a):
chemical formula 2
[A 1-(a+1.5b) B a C b ][(MN )1-x-y (L) y Ti x ]O 3-z
In the case of the formula (I) described above,
a represents Pb or Ba, and the component A is represented,
b represents at least one or more elements selected from the group consisting of Ba, ca, co, fe, ni, sn and Sr,
c represents one or more elements selected from the group consisting of Co, fe, bi, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb and Lu,
l represents a single form composed of one selected from Zr or Hf, or a mixed form thereof,
m represents at least one or more elements selected from the group consisting of Ce, co, fe, in, mg, mn, ni, sc, yb and Zn,
n represents at least one or more elements selected from the group consisting of Nb, sb, ta and W,
a. b, x, y and z represent 0<a.ltoreq.0.10, 0<b.ltoreq.0.05, 0.05.ltoreq.x.ltoreq.0.58, 0.05.ltoreq.y.ltoreq.0.62 and 0<z.ltoreq.0.02, respectively.
Based on the fact that the piezoelectric characteristics of the piezoelectric single crystal having the composition formula of chemical formula 1 or chemical formula 2 of the present invention tend to increase more as the chemical composition becomes complicated, the perovskite-type crystal structure ([ a ]][B]O 3 ) [ A ] of (2)]The bit ions are configured to have a complex composition.
At this time, specifically examined is [ A ] of the piezoelectric single crystal represented by the composition formula of chemical formula 1 or chemical formula 2]Complex composition of the bit ions, which can be configured as [ A ] 1-(a+1.5b) B a C b ]And the composition of a contains a flexible or inflexible element, in the example of the present invention, although a is limited to Pb, which is a piezoelectric single crystal of flexible series, it should not be limited thereto.
For the ion located at [ a ], a divalent metal, preferably at least one or more elements selected from the group consisting of Ba, ca, co, fe, ni, sn and Sr, is used in the composition of B, and a trivalent metal is used in the composition of C.
Preferably, one or more elements selected from the group consisting of Co, fe, bi, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb and Lu are used, and more preferably, a single form consisting of one selected from lanthanoid elements is used, or a mixed form thereof.
In the exemplary embodiment of the present invention, for the ion located at [ a ], although the composition of C is described as a composition for a single form including La or Sm, or a composition including a mixed form of two elements, it should not be limited thereto.
For [ A ] of the piezoelectric single crystal represented by the composition formula of the chemical formula 1 or the chemical formula 2 ]Complex composition of the ions in the bit corresponds to [ A ]][ A ] of the site ion 1-(a+1.5b )B a C b ]Is a necessary condition for achieving the target physical properties, and is characterized in that when a is a piezoelectric single crystal of flexible series or non-flexible series, it is constituted by mixing a divalent metal and a trivalent metal.
Preferably, for a complex composition of [ A ] site ions corresponding to the donor in the composition of the piezoelectric single crystal represented by chemical formula 1, it should satisfy 0.01.ltoreq.a.ltoreq.0.10 and 0.01.ltoreq.b.ltoreq.0.05, more preferably, a/b.ltoreq.2. At this time, in the condition, when a is less than 0.01, there is a problem that the perovskite type phase is unstable, and when a exceeds 0.10, it is not preferable, and it becomes difficult to be practical because the phase transition temperature becomes too low.
In addition, when the condition that a/b.gtoreq.2 is not satisfied, this is not preferable, dielectric and piezoelectric characteristics are not maximized, or growth of single crystals is limited.
At this time, for the composite composition of [ a ] site ions of the composition of the piezoelectric single crystal represented by chemical formula 1 or chemical formula 2, the complex composition enables realization of excellent dielectric constant as compared with the composition formed of only trivalent metal or divalent metal.
According to general known [ A ]][MN]O 3 -PbTiO 3 -PbZrO 3 From around a quasi-homotype phase boundary (MPB) between rhombohedral and tetragonal phases, a composition region exhibiting excellent dielectric and piezoelectric characteristics is revealed. In [ A ] ][MN]O 3 -PbTiO 3 -PbZrO 3 The dielectric and piezoelectric properties are maximized at the composition of the quasi-homotype phase boundary between the rhombohedral phase and tetragonal phase, and gradually decrease as the composition gradually deviates from the composition of the MPB. Further, in the case of within 5mol% of the composition of the rhombohedral phase region from the composition of the MPB, since the decrease in dielectric characteristics and piezoelectric characteristics is small, very high dielectric and piezoelectric characteristic values are maintained, and in the case of within 10mol% of the composition of the tetragonal phase region from the composition of the MPB, dielectric and piezoelectric characteristics continuously decrease, but exhibit sufficiently high dielectric and piezoelectric characteristic values suitable for dielectric and piezoelectric application parts. In the case where the composition is changed from the composition of MPB to the composition of tetragonal phase region, the decrease in dielectric and piezoelectric characteristics occurs faster than that of rhombohedral phase region. However, even in the case of within 10mol% of the composition of the tetragonal phase region and within 5mol% of the composition, the dielectric characteristics and piezoelectric characteristics are lowered, but dielectric and piezoelectric characteristic values suitable for dielectric and piezoelectric application parts are exhibited sufficiently high.
PbTiO 3 And PbZrO 3 The quasi-homotypic phase boundary (MPB) between is known as PbTiO 3 :PbZrO 3 X, y=0.48:0.52 (molar ratio).
In the case where the composition of 5mol% is changed from the composition of MPB to the composition of each region of rhombohedral phase and tetragonal phase, the maximum value of x and the maximum value of y become 0.53 and 0.57, respectively (in other words, x: y represents 0.53:0.47 when x is the maximum value, and x: y represents 0.43:0.57 when y is the maximum value). In addition, in the case where the composition of 10mol% is changed from the composition of MPB to the composition of each region of rhombohedral phase and tetragonal phase, the maximum value of x and the maximum value of y become 0.58 and 0.62, respectively (in other words, x: y represents 0.58:0.42 when x is the maximum value, and x: y represents 0.38:0.62 when y is the maximum value). The high dielectric and piezoelectric characteristic values are maintained in a range of up to 5mol% of the composition of each region of the rhombohedral phase and tetragonal phase from the composition of the MPB, and the dielectric and piezoelectric characteristic values suitable for dielectric and piezoelectric application parts are exhibited sufficiently high in a range of up to 10mol% of the composition of each region of the rhombohedral phase and tetragonal phase from the composition of the MPB.
In addition, in PbTiO 3 And PbZrO 3 In the case where the content of (a) is 0.05 or less, i.e., the values of x and y, the present invention is not suitable because a quasi-type phase boundary between rhombohedral phase and tetragonal phase cannot be formed or the phase transition temperature and coercive electric field are too low.
Thus, for the position corresponding to the receptor in the composition of the piezoelectric single crystal represented by the composition formula of the chemical formula 1 or the chemical formula 2 [ B ]]The complex composition of the ions at this point preferably falls within the range of 0.05.ltoreq.x.ltoreq.0.58, more preferably 0.10.ltoreq.x.ltoreq.0.58. At this time, this is because in the case where x is less than 0.5, the phase transition temperature T C And T RT Low piezoelectric charge constant d 33 And k 33 Low, or coercive electric field E C Low, and because in the case where x exceeds 0.58, the dielectric constant K 3 T Low piezoelectric charge constant d 33 And k 33 Low, or phase transition temperature T RT Low. Meanwhile, y falls preferably within a range of 0.05.ltoreq.y.ltoreq.0.62, more preferably 0.10.ltoreq.y.ltoreq.0.62. This is because in the case where y is less than 0.05, the phase transition temperature T C And T TRT Low piezoelectric charge constant d 33 And k 33 Low, or coercive electric field E C Low, and in the case where y exceeds 0.62, the dielectric constant K 3 T Low, or piezoelectric charge constant d 33 And k 33 Low.
The invention is formed byPiezoelectric single crystal represented by the compositional formula of chemical formula 1 or chemical formula 2 has perovskite crystal structure ([ a)][B]O 3 ) Middle position [ B ]]The ion contains tetravalent metal, and in particular, the composition form of L is limited to a single form composed of one selected from Zr or Hf or a mixed form thereof.
When the composition has a mixed form, a piezoelectric single crystal represented by the following composition formula of chemical formula 3 or chemical formula 4 is provided:
chemical formula 3
[A 1-(a+1.5b) B a C b ][(MN) 1-x-y (Zr 1-w ,Hf w ) y Ti x ]O 3
Chemical formula 4
[A 1-(a+1.5b) B a C b ][(MN) 1-x-y (Zr 1-w ,Hf w ) y Ti x ]O 3-z
In the formula, A, B, C, M and N are the same as those shown in the chemical formula 1 or chemical formula 2, and a, b, x and y are also the same as those shown in the formulae, but w represents 0.01.ltoreq.w.ltoreq.0.20.
At this time, when the w is less than 0.01, there is a problem in that dielectric and piezoelectric characteristics are not maximized, and when it exceeds 0.20, it is not preferable that dielectric and piezoelectric characteristics suddenly decrease.
With respect to the piezoelectric single crystal according to the first exemplary embodiment of the present invention, the exemplary embodiment is described in detail based on the piezoelectric single crystal having a perovskite structure represented by the composition formula of the following chemical formula 5:
chemical formula 5
[Pb 1-(a+1.5b) Sr a C b ][(MN) 1-x-y (Zr) y Ti x ]O 3
In the case of the formula (I) described above,
c represents one or more elements selected from the group consisting of Co, fe, bi, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb and Lu,
m represents at least one or more elements selected from the group consisting of Ce, co, fe, in, mg, mn, ni, sc, yb and Zn,
n represents at least one or more elements selected from the group consisting of Nb, sb, ta and W, and
a. b, x and y are 0.02.ltoreq.a.ltoreq.0.10, 0.005.ltoreq.b.ltoreq.0.05, 0.35.ltoreq.x.ltoreq.0.58 and 0.05.ltoreq.y.ltoreq.0.62, respectively.
As a result, with respect to the composition of the piezoelectric single crystal represented by the chemical formula 5, although it is described that the coercive electric field and the internal bias electric field are effectively increased by limiting the composition ratio of the donor and the acceptor while maintaining the high dielectric constant, the high piezoelectric charge constant, and the high coercive electric field inherent to the piezoelectric single crystal, the composition and the composition ratio are not limited thereto, and various changes and modifications can be made within the composition range of chemical formula 1.
Fig. 1 to 3 are photographs showing a piezoelectric single crystal having a perovskite type structure manufactured according to a first exemplary embodiment of the present invention, and it can be confirmed that the appearance of the single crystal becomes different according to the variation of the composition ratio of a donor and an acceptor and the atmosphere at the time of single crystal growth.
Further, as shown in fig. 4 to 6, with respect to the composition of the piezoelectric single crystal according to the first exemplary embodiment, when the donor content and the acceptor content, preferably the Mn content, are adjusted to be most suitable, the coercive electric field and the internal bias electric field are effectively increased, and thus the stability of the piezoelectric single crystal at the time of electric field driving and under the condition of mechanical load is increased.
In addition, fig. 7 to 9 present a control donor and a crystal structure having perovskite type ([ a ] according to a second exemplary embodiment of the present invention ][B]O 3 ) Piezoelectric single crystal of (C)]Oxygen vacancies at the single crystal become different in appearance.
At this time, with the piezoelectric single crystal according to the second exemplary embodiment, it is characterized in that the oxygen vacancy at [ O ] is controlled to 0.ltoreq.z.ltoreq.0.02. When z exceeds 0.02, it is not preferable that dielectric and piezoelectric characteristics suddenly decrease.
When oxygen vacancies are induced into this range, as shown in fig. 10, the coercive electric field and the internal bias electric field effectively increase, so that the stability of the piezoelectric single crystal at the time of electric field driving and under mechanical load conditions increases. Therefore, the piezoelectric characteristics can be maximized, and the stability can also be enhanced.
The piezoelectric single crystal represented by the composition formula of chemical formula 1 or chemical formula 2 is a piezoelectric single crystal in which a perovskite-type crystal structure ([ a)][B]O 3 ) Middle [ A ]]Complex composition of the site ion and its location in [ B ]]Ion at and located at [ O ]]The composition of the ions at this point mixes such that the Curie temperature T C At a temperature of 180 ℃ or above, and at the same time, the phase transition temperature T between the rhombohedral phase and the tetragonal phase RT Is 100 ℃. At this time, when the Curie temperature T c Below 180 c, the problem is that it is difficult to apply the coercive electric field E C Raise the phase transition temperature to above 5kV/cm or T RT Raising the temperature to above 100 ℃.
Furthermore, the piezoelectric single crystal represented by the composition formula of chemical formula 1 or chemical formula 2 of the present invention exhibits a longitudinal electromechanical coupling coefficient k 33 Above 0.85, when the longitudinal electromechanical coupling coefficient is less than 0.85, this is not preferable in the following aspects: the characteristics become similar to those of piezoelectric polycrystalline ceramics, and the energy conversion efficiency becomes low.
Further, with the piezoelectric single crystal represented by the composition formula of chemical formula 1 or chemical formula 2 of the present invention, the composition gradient inside the single crystal is formed in the range of 0.2 to 0.5mol%, so that a single crystal having uniformity can be provided.
Due to lead zirconate (PbZrO 3 ) Has a high phase transition temperature of 230 ℃ and also effectively makes the homomorphic phase boundary (MPB) more perpendicular to the temperature axis, so that a high phase transition temperature T between rhombohedral phase and tetragonal phase can be obtained RT While maintaining a high Curie temperature, it is also possible to develop a display Curie temperature T c And phase transition temperature T RT While at the same time being of higher composition.
This is because the phase transition temperature increases in proportion to the content of lead zirconate even when the lead zirconate is mixed into a conventional piezoelectric single crystal composition. Accordingly, a piezoelectric single crystal having a perovskite-type crystal structure including zirconium (Zr) or lead zirconate can overcome the problems of the existing piezoelectric single crystal. In addition, since zirconia (ZrO 2 ) Or lead zirconate is used as the main component of the existing piezoelectric single crystal material and is also an inexpensive material, and thus can be used without improvementThe object of the invention is achieved at the material price of the single crystal.
In contrast, unlike PMN-PT, PZN-PT, and the like, a perovskite-type piezoelectric single crystal containing lead zirconate exhibits non-uniform melting behavior at the time of melting, rather than uniform melting behavior. Thus, in the case of exhibiting inconsistent melting behavior, lead zirconate is divided into liquid phase zirconia and solid phase zirconia (ZrO 2 ) Since solid-phase zirconia particles in the liquid phase inhibit single crystal growth, piezoelectric single crystals cannot be produced by using only the flux method, the Bridgman method, or the like, which is a general single crystal growth method using a melting process.
In addition, it is difficult to produce a single crystal containing a reinforced second phase by a general single crystal growth method using a melting process, and production of the single crystal has never been reported. This is because the strengthening second phase chemically reacts to the liquid phase due to its instability above the melting temperature, and is therefore removed without maintaining the separate second phase form. In addition, since the separation between the second phase and the liquid phase occurs due to the density difference between the second phase and the liquid phase, it is difficult to produce a single crystal containing the second phase, and it is also impossible to adjust the volume fraction, size, shape, arrangement, distribution, etc. of the reinforcing second phase inside the single crystal.
Thus, according to the present invention, a piezoelectric single crystal containing a reinforced second phase is produced using a solid phase single crystal growth method that does not use a melting process. In the solid phase single crystal growth method, single crystal growth occurs below the melting temperature, and thus chemical reaction between the strengthening second phase and the single crystal is controlled, and the strengthening second phase becomes stably present in the single crystal in a single form.
In addition, single crystal growth starts from a polycrystalline phase containing the strengthening second phase, and there is no change in the volume fraction, size, shape, arrangement, distribution, etc. of the strengthening second phase during single crystal growth. Therefore, when the volume fraction, size, shape, arrangement, distribution, and the like of the reinforced second phase inside the polycrystal are controlled and the single crystal is grown in the process of preparing the polycrystal including the reinforced second phase, as a result, a single crystal including the reinforced second phase in a desired form, that is, a reinforced piezoelectric single crystal (second-phase reinforced single crystal) can be produced.
When the flux method and the Bridgman method, which are conventional single crystal growth methods, are used, it is impossible to produce a crystal structure ([ A ] for perovskite type][B]O 3 ) Piezoelectric single crystals having a complex composition. In particular, in the case of the flux method including the melting process and the Bridgman method, the single crystal may be produced in such a manner that the composition gradient inside the single crystal is 1 to 5mol% or more, whereas in the case of the solid phase single crystal growth method of the present invention, a single crystal of uniform composition in which the composition gradient inside the single crystal is 0.2 to 0.5mol% may be produced.
Thus, in the present invention, for the perovskite-type crystal structure ([ A ] containing lead zirconate) using the solid phase single crystal growth method][B]O 3 ) Even if mixing [ A]Complex composition of the site ion and [ B ]]The composition of the bit ions forms a complex composition, and the piezoelectric single crystal is also grown uniformly, so that it is possible to provide a piezoelectric material exhibiting a significantly enhanced dielectric constant (K 3 T 4000 to 15000), piezoelectric charge constant (d) 33 More than or equal to 1400 to 6000 pC/N) and a high coercive electric field (E) C Not less than 3.5 to 12 kV/cm).
In particular, coercive electric field E C When the coercive electric field is less than 3.5kV/cm, more preferably 4 to 12kV/cm, there is a problem in that polarization is easily removed when processing a piezoelectric single crystal or when manufacturing or using a member to which the piezoelectric single crystal is applied.
In addition, due to the high internal bias electric field E necessary for the electrical stability of the piezoelectric single crystal I And is 0.5kV/cm or more, more preferably 0.5 to 3.0kV/cm, thereby simultaneously having the characteristics, and thus has advantages that it can be used for a wide temperature range and operating voltage conditions.
The invention provides a method for preparing piezoelectric single crystals by using solid phase single crystal growth. The solid phase single crystal growth method is based on patent documents 1 and 2, and piezoelectric single crystals grown by the solid phase single crystal growth method can be mass-produced at low process cost as compared with those grown by the flux method and the bridgman method.
Specifically, the method for producing a piezoelectric single crystal according to the present invention comprises: a step (a) of reducing the number density of abnormal grains (i.e., the number of abnormal grains per unit area) by adjusting the average size of matrix grains having a polycrystal constituting the composition of the piezoelectric single crystal; and a step (b) of growing abnormal grains by heat-treating the polycrystal exhibiting a decrease in the number density of abnormal grains obtained through the step (a), wherein a powder constituting the composition of the piezoelectric single crystal is calcined at a temperature of less than 800 to 900 ℃ to obtain a powder molded article, and a first heat-treating process of sintering the powder molded article and a second heat-treating process of growing a single crystal are performed.
Further, as other manufacturing methods, there is provided a manufacturing method of a piezoelectric single crystal in such a manner that the polycrystal is heat-treated under a condition that the number density of abnormal crystal grains is reduced as the average size of the matrix crystal grains of the polycrystal having the composition is adjusted.
In the above facts, a single crystal can be obtained in such a manner that only a small number of abnormal crystal grains generated in a state where the number density of abnormal crystal grains of a polycrystal is reduced are continuously grown.
The following method for producing a piezoelectric single crystal can be provided in the following manner: by combining the seed single crystal with the polycrystalline body prior to the heat treatment of the polycrystalline body, the seed single crystal is continuously grown within the polycrystalline body during the heat treatment.
The average size R of the polycrystalline matrix grains is adjusted to an average size R of matrix grains with respect to a critical size (the number density of abnormal grains is shown to become "0 (zero)") c ) Up to a size in the range of 0.5 to 2 times (0.5R c ≤R≤2R c ). At this time, the average size of matrix grains in the polycrystal is smaller than 0.5R c (0.5Rc>R) no single crystal growth due to an excessively high number density of abnormal grains, while the average size of the matrix grains in the polycrystal is more than 2R c (2R c <R) is a number density of "0", but since the growth rate of the single crystal is too slow, a large single crystal cannot be produced.
With the method for producing a piezoelectric single crystal of the present invention, the first heat treatment process and the second heat treatment process are carried out at 900 to 1300 ℃ for 1 to 100 hours, and preferably the heat treatment is carried out at a temperature rise rate up to 1 to 20 ℃/min.
The heat treatment may be performed by adjusting the partial pressure of oxygen. At this time, the partial pressure of oxygen can be adjusted in air, N 2 Atmosphere or H 2 -N 2 Is carried out under the condition of atmosphere, and realizes that the dielectric constant and the piezoelectric charge constant continuously decrease with the decrease of the oxygen partial pressure in the atmosphere, but the coercive electric field E c And an internal bias electric field E I Physical properties of increased propensity.
In addition, the piezoelectric single crystal having a perovskite type structure may cause an increase in the magnitude of the internal bias electric field because of defective dipoles caused by a combination of acceptors and oxygen vacancies.
Therefore, in the case where the density of oxygen vacancies increases due to the addition of the acceptor inside the piezoelectric single crystal, the density of defect dipoles naturally increases, and as a result, the internal bias electric field increases as well as the coercive electric field increases.
Therefore, when the single crystal growth using the first and second heat treatment processes is insufficient, or in order to accelerate the growth, a third heat treatment process for the grown single crystal is further performed, so that the oxygen vacancy content inside the piezoelectric single crystal can be adjusted.
At this time, the temperature and time required for the third heat treatment process may be varied depending on the oxygen atmosphere, but it is preferable that the third heat treatment process be performed at 600 to 1300 ℃ for 0.1 to 100 hours.
Further, in the manufacturing method of the present invention, in the third heat treatment process additionally performed after the single crystal growth process, the oxygen vacancy content (0<z.ltoreq.0.02) is adjusted by the condition of the oxygen partial pressure in the atmosphere, and thus the piezoelectric single crystal according to the second exemplary embodiment can be manufactured.
Therefore, since the atmosphere [ the magnitude of partial pressure of oxygen ] is adjusted during the heat treatment for growing single crystals ]Can induce an internal bias electric field E which is not present in a general PMN-PT single crystal sufficiently large I Thus, a novel piezoelectric single crystal having a large resistance to the external environment can be produced.
Furthermore, the present invention provides a piezoelectric body including only a piezoelectric single crystal or a mixture of a piezoelectric single crystal and a polymer.
Although the polymer is not particularly limited, as a representative example, when the epoxy resin is used in a mixed state, the polymer may be provided in a form that is relatively resistant to mechanical impact and is easily machined.
Furthermore, the present invention can provide a piezoelectric application part and a dielectric application part using a piezoelectric body, and examples of the piezoelectric and dielectric application parts include an ultrasonic transducer (an ultrasonic inspection meter for medical treatment, a transducer for sonor (acoustic navigation ranging), a transducer for nondestructive inspection, an ultrasonic cleaner, an ultrasonic motor, etc.), a piezoelectric actuator (d 33 Actuator d 31 Actuator d 15 A piezoelectric actuator, a piezoelectric actuator for controlling a minute position, a piezoelectric pump, a piezoelectric valve, a piezoelectric speaker, and the like), a piezoelectric sensor (a piezoelectric gravimeter, and the like), an electric field generating transducer, and an electric field vibration generating transducer.
Further, examples of the dielectric application component include a capacitor, an infrared sensor, a dielectric filter, and the like having high efficiency.
Examples
Hereinafter, the present invention will be described in detail based on examples.
The present embodiments are intended to more specifically describe the present invention, and the scope of the present invention should not be construed as being limited to these embodiments.
Part 1: production of piezoelectric Single Crystal according to the first exemplary embodiment, evaluation of dielectric and piezoelectric Properties
< example 1> production of piezoelectric Single Crystal containing internal bias electric field 1
Production of [ Pb ] by solid phase Single Crystal growth method 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x is more than or equal to 0.0 and less than or equal to 0.02[ donor content ]]The method comprises the steps of carrying out a first treatment on the surface of the Y is more than or equal to 0.0 and less than or equal to 0.1[ acceptor content ]]) Is a piezoelectric single crystal of (a).
Excess MgO and PbO were added during the powder synthesis so that the MgO-containing second phase and the pore-strengthening phase were contained at 2% by volume.First, as shown in Table 1 below, the composition [ Pb ] was obtained by the niobium-iron ore method 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (0.0.ltoreq.x.ltoreq. 0.02,0.0.ltoreq.y.ltoreq.0.1). First, to mix MgO powder and Nb by ball milling 2 O 5 MgNb is prepared by mixing powders and calcining them 2 O 6 The perovskite phase powder is produced by mixing and calcining the raw material powder again in a quantitative ratio. The mixed powder is manufactured by adding excess PbO and MgO to the resulting powder. After the mixed powder was molded, it was compression molded under a hydrostatic pressure of 200MPa, and each powder molded article was subjected to heat treatment at 25 ℃ intervals for up to 100 hours under various temperature conditions of 900 ℃ to 1300 ℃.
Under the condition that the average size R of the polycrystalline matrix grains can be adjusted to a size range of 0.5 times or more and 2 times or less (0.5 Rc.ltoreq.R.ltoreq.2Rc) which results in generation of abnormal grains, the amount of the excessively added PbO is determined to be in the range of 10 to 20mol% and the heat treatment temperature is determined to be in the range of 1000 to 1200 ℃. Placing Ba (Ti) 0.7 Zr 0.3 )O 3 The single crystal having a polycrystalline composition is produced by performing a heat treatment (heat treatment for single crystal growth) in a state of a seed single crystal and continuously growing the single crystal inside the polycrystalline.
When the average size R of the polycrystalline matrix grains is adjusted to a critical size (average size R of matrix grains showing that the number density of the abnormal grains becomes "0 (zero)") which results in the generation of the abnormal grains c ) In a size range of 0.5 to 2 times (0.5R) c ≤R≤2R c ) In this case, the seed single crystal is continuously grown inside the polycrystal. In the present embodiment, when the amount of excess PbO and the heat treatment temperature are adjusted, the average size R of the polycrystalline matrix grains may be adjusted to a size range of 0.5 times or more and 2 times or less of the critical size that causes abnormal grains to be generated. When the polycrystalline substrate is to be used When the average size R of the interstitial grains is adjusted to be within the range of the size (0.5 Rc.ltoreq.R.ltoreq.2 Rc), the heat treatment is carried out in [ Pb ] 0.98- 1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.y.ltoreq.0.1) of Ba (Ti) continuously growing inside the polycrystal 0.7 Zr 0.3 )O 3 And thus a single crystal having the same composition as the polycrystal is produced. At this time, the grown single crystal had a size of 20X 20mm 2 The above.
Regarding one example of the piezoelectric single crystal manufactured as described above, FIG. 1 shows [ Pb 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.1; y=0) piezoelectric single crystal, fig. 2 shows [ Pb 0.98- 1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.01; y=0.05). At this time, in fig. 2, the piezoelectric single crystal is black by adding Mn under air, i.e., an atmosphere condition in which the single crystal grows.
In addition, the piezoelectric single crystal may be manufactured in such a manner that the partial pressure of oxygen in the atmosphere is changed during the heat treatment of the first sintering of the ceramic powder molded article and the single crystal growth, and as an example thereof, [ Pb ] shown in FIG. 3 may be manufactured 0.98- 1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.01; y=0.05). At this time, at N 2 -H 2 That is, the addition of Mn under the atmosphere conditions for single crystal growth confirmed that the piezoelectric single crystal was black.
< example 2> production of piezoelectric Single Crystal containing internal bias electric field 2
By and with the saidThe same procedure as performed in example 1 was followed to produce [ Pb ] 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/ 3 Nb 2/3 ) 0.25 (Ni 1/3 Nb 2/3 ) 0.10-y (Mn 1/3 Nb 2/3 ) y Zr 0.30 Ti 0.35 ]O 3 (x is more than or equal to 0.0 and less than or equal to 0.02[ donor content ]]The method comprises the steps of carrying out a first treatment on the surface of the Y is more than or equal to 0.0 and less than or equal to 0.1[ acceptor content ]]) Is a piezoelectric single crystal of (a).
Experimental example 1> evaluation of dielectric and piezoelectric characteristics related to piezoelectric single crystal shown in example 1
For [ Pb ] produced in said example 1 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x is more than or equal to 0.0 and less than or equal to 0.02[ donor content ]]The method comprises the steps of carrying out a first treatment on the surface of the Y is more than or equal to 0.0 and less than or equal to 0.1[ acceptor content ]]) The dielectric and piezoelectric characteristics of the piezoelectric single crystals produced in such a manner that the composition (variations of x and y) of the piezoelectric single crystals shown in table 1 and the partial pressure of oxygen in the atmosphere in the first sintering process for ceramic powder molding and the heat treatment for single crystal growth shown in table 2 were adjusted were evaluated.
Specifically, for [ Pb ] produced as described above 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.y.ltoreq.0.1) single crystal, x [ donor content ] measured by IEEE method using an impedance analyzer or the like]And y [ Mn content ]]Dielectric constant and phase transition temperature T caused by variation of (C) c And T RT Piezoelectric charge constant, coercive electric field E c And an internal bias electric field E I The respective changes in the characteristics are shown in table 1 below.
[ Table 1 ]
As can be confirmed from table 1 above, in the piezoelectric single crystal (x=0.0, y=0.05) In the case of comparative example 1, as a result of evaluating the piezoelectric charge constant, dielectric constant and dielectric loss characteristics, the piezoelectric charge constant d 33 1600pC/N has a dielectric constant of 5640 and a dielectric loss tan delta of 0.4%, and thus is excellent in dielectric and piezoelectric characteristics. At this time, the internal bias electric field E I 0.4.
In addition, in the case of (001) piezoelectric single crystal (x=0.01, y=0.0) (comparative example 2), the piezoelectric charge constant d 33 2650pC/N, dielectric constant 8773, dielectric loss tan. Delta. Of 0.5%. At this time, the internal bias electric field E I Is 0.
In contrast, in terms of x [ donor content ]]And y [ Mn content ]]In the case of a piezoelectric single crystal produced by variation of (1), the content of the donor is changed with x]The dielectric constant and the piezoelectric charge constant increase with the y Mn content]The dielectric constant and the piezoelectric charge constant continuously decrease, but the coercive electric field E C And an internal bias electric field E I And (3) increasing.
As shown in Table 1, the piezoelectric single crystal of the present invention has a donor content of x]And y [ Mn content ]]When the value of (a) exceeds a certain value (x.noteq.0 and y.noteq.0.0), the dielectric constant and the piezoelectric charge constant are kept similar to those of a general PMN-PT single crystal, and the coercive electric field E C And an internal bias electric field E I Can be greatly increased. In particular, since the internal bias electric field E which is not present in the general PMN-PT single crystal can be induced sufficiently large I Thus, a novel piezoelectric single crystal having a large resistance to the external environment has been developed.
In addition, regarding [ Pb ] produced as described above 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 The physical properties described in Table 2 below are the results of observing that the physical properties of the piezoelectric single crystal change with the change in atmosphere (the magnitude of partial pressure of oxygen) during the first sintering and the heat treatment for single crystal growth, respectively.
[ Table 2 ]
As shown in Table 2 above, as the magnitude of the partial pressure of oxygen in the atmosphere decreases during the first sintering and the heat treatment for single crystal growth, the dielectric constant and the piezoelectric charge constant decrease continuously, but the coercive electric field E C And an internal bias electric field E I And (3) increasing.
With x [ donor content ]]And y [ Mn content ]]The value of (c) becomes larger and the effect tends to increase more. Thus, when the composition containing x [ donor content ] is produced under conditions of low partial pressure of oxygen]And y [ Mn content ]]The dielectric constant and the piezoelectric charge constant remain similar to those of a general PMN-PT single crystal while the coercive electric field E C And an internal bias electric field E I Can be greatly increased.
As described above, according to the present invention, since it is possible to adjust the atmosphere [ the magnitude of partial pressure of oxygen ] during the first sintering and the heat treatment for single crystal growth]Sufficiently large to induce an internal bias electric field E that is not present in a general PMN-PT single crystal I A novel piezoelectric single crystal having a large resistance to the external environment can be developed.
Based on the result, for [ Pb ] 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.y.ltoreq.0.1), in adjusting "x [ donor content ]]"," y [ Mn content]"and" x/y ratio "and simultaneously adjusting the atmosphere [ the magnitude of partial pressure of oxygen ] during the first sintering and the heat treatment for single crystal growth]In the case of (2), the piezoelectric charge constant and coercive electric field E of the produced piezoelectric single crystal were confirmed C And an internal bias electric field E I May be most suitable. Thus, it contains more than a specific size (E I >0.5 or 1.0 kV/cm) of the internal bias electric field E I Is characterized in that they stably maintain their high-voltage electric characteristics against changes in the external environment, unlike conventional general PMN-PT or PIN-PMN-PT single crystals.
Experimental example 2> evaluation of dielectric and piezoelectric characteristics related to piezoelectric single crystal shown in example 2
For the piezoelectric single crystal [ Pb ] produced in the example 2 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.25 (Ni 1/ 3 Nb 2/3 ) 0.10-y (Mn 1/3 Nb 2/3 ) y Zr 0.30 Ti 0.35 ]O 3 (x is more than or equal to 0.0 and less than or equal to 0.02[ donor content ]]The method comprises the steps of carrying out a first treatment on the surface of the Y is more than or equal to 0.0 and less than or equal to 0.1[ acceptor content ]]) The dielectric and piezoelectric characteristics of the piezoelectric single crystals produced in such a manner that the composition (variations in x and y) of the piezoelectric single crystals shown in table 3 and the partial pressure of oxygen in the atmosphere in the first sintering process for ceramic powder molded articles and the heat treatment for single crystal growth shown in table 4 were adjusted were evaluated.
Measuring [ Pb ] by IEEE method using impedance analyzer or the like 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.25 (Ni 1/ 3 Nb 2/3 ) 0.10-y (Mn 1/3 Nb 2/3 ) y Zr 0.30 Ti 0.35 ]O 3 (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.y.ltoreq.0.1) dielectric constant, phase transition temperature T of the piezoelectric single crystal C And T RT Piezoelectric charge constant, coercive electric field E C And an internal bias electric field E I The respective changes in the characteristics are shown in table 3 below.
[ Table 3 ]
As a result of evaluating the piezoelectric charge constant, dielectric constant and dielectric loss of each single crystal shown in Table 3, the method for producing [ Pb ] by the solid phase single crystal growth method 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.25 (Ni 1/3 Nb 2/3 ) 0.10-y (Mn 1/3 Nb 2/3 ) y Zr 0.30 Ti 0.35 ]O 3 (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.y.ltoreq.0.1) in the case of the composition (x=0.0, y=0.05) (comparative example 3), toAnd in the case of the composition (x=0.01, y=0.0) (comparative example 4), the piezoelectric charge constant d was confirmed 33 Excellent in dielectric constant and dielectric loss tan delta, but the internal bias electric field E I Lower or no induction.
Therefore, as shown in Table 3, in the piezoelectric single crystal of the present invention, when the values of x and y exceeded a certain value (x. Noteq.0.0 and y. Noteq.0.0), it was confirmed that the dielectric constant and the piezoelectric charge constant remained similar to those shown in the general PMN-PT single crystal, and that the coercive electric field E was also maintained C And an internal bias electric field E I Can be greatly increased.
In particular, since the internal bias electric field E which is not present in a general PMN-PT single crystal can be induced sufficiently large I Therefore, a novel piezoelectric single crystal having a large resistance to the external environment can be developed.
For [ Pb ] produced as described above 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.25 (Ni 1/3 Nb 2/3 ) 0.10-y (Mn 1/ 3 Nb 2/3 ) y Zr 0.30 Ti 0.35 ]O 3 The physical properties described in Table 4 below are the results obtained by observing that the physical properties of the piezoelectric single crystal are each changed with the change in the atmosphere (the magnitude of the partial pressure of oxygen) during the first sintering and the heat treatment for single crystal growth.
[ Table 4 ]
As shown in Table 4 above, as the magnitude of the partial pressure of oxygen in the atmosphere during the first sintering and the heat treatment for single crystal growth is reduced, the dielectric constant and the piezoelectric charge constant are continuously reduced, but the coercive electric field E C And an internal bias electric field E I And (3) increasing.
This effect tends to follow the x [ donor content ]]And y [ Mn content ]]The value of (2) becomes larger and increases more when the composition containing x [ donor content ] is produced under the condition of lower oxygen partial pressure]And y [ Mn content ]]In the case of the piezoelectric single crystal of (2), the dielectric was confirmedThe constant and piezoelectric charge constant remain similar to those shown for a typical PMN-PT single crystal, while the coercive electric field E C And an internal bias electric field E I Can be greatly increased.
Thus, according to the present invention, since it is possible to adjust the atmosphere [ the magnitude of partial pressure of oxygen ] during the first sintering and the heat treatment for single crystal growth]Sufficiently large to induce an internal bias electric field E that is not present in a general PMN-PT single crystal I Therefore, a novel piezoelectric single crystal having a large resistance to the external environment can be developed.
Based on the result, for [ Pb ] 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.25 (Ni 1/3 Nb 2/3 ) 0.10-y (Mn 1/ 3 Nb 2/3 ) y Zr 0.30 Ti 0.35 ]O 3 (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.y.ltoreq.0.1), in adjusting "x [ donor content ]]"," y [ Mn content]"and" x/y ratio "and simultaneously adjusting the atmosphere [ the magnitude of partial pressure of oxygen ] during the first sintering and the heat treatment for single crystal growth]In the case of (2), the piezoelectric charge constant and coercive electric field E of the produced piezoelectric single crystal were confirmed C And an internal bias electric field E I May be most suitable. Thus, it contains more than a specific size (E I >0.5 or 1.0 kV/cm) of the internal bias electric field E I Is characterized in that they stably maintain their high-voltage electric characteristics against changes in the external environment, unlike conventional general PMN-PT or PIN-PMN-PT single crystals.
< Experimental example 3> observation of changes in internal bias electric field due to temperature changes
Production of [ Pb ] shown in example 1 by solid phase Single Crystal growth 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 Each of (x=0.01; y=0.05) piezoelectric single crystals and general PMN-30PT piezoelectric single crystals. Using the piezoelectric single crystal produced as described above, a measurement sample having a size of "(001) 4×4×0.5 (T) mm" was produced, and the coercive electric field E was observed C And an internal bias electric field E I Each as a function of temperature rise.
FIG. 4 is a diagram showing [ Pb ] of the embodiment 1 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.01; y=0.05), and changes in the coercive electric field and the internal bias electric field are observed while raising the temperature at ordinary temperature.
As a result, at 25℃the coercive electric field E C And an internal bias electric field E I 4.4 and 1.0kV/cm respectively, when the temperature is raised to 80℃the coercive electric field E C And the internal bias electric field was reduced to 2.3 and 0.6kV/cm, respectively.
FIG. 5 is a graph obtained by observing changes in polarization-electric field of a general PMN-30PT piezoelectric single crystal [ single crystal growth atmosphere-air ] produced by a solid phase single crystal growth method, and changes in coercive electric field and internal bias electric field are observed while raising the temperature at ordinary temperature.
As a result, the coercive electric field was 2.5kV/cm, and no internal bias electric field was observed. Furthermore, when the temperature was increased to 80 ℃, the coercive electric field was significantly reduced to 1.2kV/cm.
Based on the result, for [ Pb ] shown in the embodiment 1 of the present invention 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.01; y=0.05) [ single crystal growth atmosphere—air]Coercive electric field ratio of general PMN-30PT piezoelectric single crystal [ single crystal growth atmosphere-air ]]About twice, in particular the piezoelectric single crystal has the property of containing an internal bias electric field.
In addition, it can maintain the coercive electric field and the internal electric field even if the temperature is raised, exhibiting the property of maintaining the property without depolarization with temperature change. In particular, [ Pb ] at 80℃was confirmed 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/ 3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.01; y=0.05) [ single crystal growth atmosphere—air]PMN-30PT piezoelectric single crystal [ single crystal growth atmosphere-air ] at normal temperature]Similarly, and the piezoelectric single crystal maintains an internal bias electric field and exhibits high stability.
< Experimental example 4> observation of the variation of the internal bias electric field with the partial pressure condition of oxygen
Production of [ Pb ] shown in example 1 by solid phase Single Crystal growth 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.01; y=0.1). First sintering during manufacture and N during heat treatment for single crystal growth 2 -H 2 Under an atmosphere, a coercive electric field E was observed using a measurement sample having a size of "(001) 4×4×0.5 (T) mm" produced from a piezoelectric single crystal produced by adjusting the partial pressure of oxygen C And an internal bias electric field E I Variations of each.
FIG. 6 is [ Pb ] 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.4-y (Mn 1/3 Nb 2/3 ) y Zr 0.25 Ti 0.35 ]O 3 (x=0.01; y=0.1, example 1 to 4) piezoelectric single crystal [ single crystal growth atmosphere—n 2 -H 2 ]Wherein it was confirmed that x [ donor content ] was produced under conditions of low oxygen partial pressure]And y [ Mn content ]]When the piezoelectric single crystal exceeds a certain size, the coercive electric field E C And an internal bias electric field E I Can be greatly increased to 5.6 kV/cm and 2.8kV/cm respectively.
Based on the above facts, it was confirmed that it is possible to adjust the atmosphere [ the magnitude of partial pressure of oxygen ] during the first sintering and the heat treatment for single crystal growth]And simultaneously adjusting the x [ donor content ] in the composition of the piezoelectric single crystal]And y [ Mn content ]]But is large enough to induce an internal bias electric field E which is not present in a general PMN-PT single crystal I 。
Part 2: production of piezoelectric Single Crystal according to the second exemplary embodiment and evaluation of dielectric and piezoelectric Properties
< example 3> production of piezoelectric Single Crystal containing oxygen vacancy 1
Production of [ Pb ] by solid phase Single Crystal growth method 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (x is more than or equal to 0.0 and less than or equal to 0.02[ donor content ]]The method comprises the steps of carrying out a first treatment on the surface of the Piezoelectric single crystal with z being more than or equal to 0.0 and less than or equal to 0.03[ oxygen vacancy content ].
Excess MgO and PbO were added during the powder synthesis so that the MgO-containing second phase and the pore-strengthening phase were contained at 2% by volume. First, as shown in Table 5 below, the composition [ Pb ] was obtained by the niobium-iron ore method 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/ 3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.z.ltoreq.0.03). First, to mix MgO powder and Nb by ball milling 2 O 5 MgNb is prepared by mixing powders and calcining them 2 O 6 In addition, the perovskite type powder is produced by mixing the raw material powders again in a quantitative ratio and calcining (calcining process). The mixed powder is manufactured by adding excess PbO and MgO to the resulting powder. After the mixed powder was molded, it was compression molded under a hydrostatic pressure of 200MPa, and each powder molded article was subjected to heat treatment at 25 ℃ intervals for up to 100 hours under various temperature conditions of 900 ℃ to 1300 ℃. Under the condition that the average size R of the polycrystalline matrix grains can be adjusted to a size range of 0.5 times or more and 2 times or less (0.5 Rc.ltoreq.R.ltoreq.2Rc) than the critical size causing generation of abnormal grains, the amount of the excessively added PbO is determined to be in the range of 10 to 20mol% and the heat treatment temperature is determined to be in the range of 1000 to 1200 ℃. Placing Ba (Ti) 0.7 Zr 0.3 )O 3 Performing a heat treatment process (heat treatment for single crystal growth, second heat treatment process) in a state of a seed single crystal, and manufacturing a semiconductor device having a plurality of semiconductor devices by continuously growing single crystals inside a polycrystalline bodySingle crystals of the crystal composition.
When the average size R of the polycrystalline matrix grains is adjusted to a critical size (average size R of matrix grains showing that the number density of the abnormal grains becomes "0 (zero)") which results in the generation of the abnormal grains c ) In a size range of 0.5 to 2 times (0.5R) c ≤R≤2R c ) In this case, the seed single crystal is continuously grown inside the polycrystal. In the present embodiment, when the amount of PbO excessively added and the heat treatment temperature are adjusted, the average size R of the polycrystalline matrix grains may be adjusted to a size range of 0.5 times or more and 2 times or less of the critical size that causes abnormal grains to be generated. When the average size R of the polycrystalline matrix grains is adjusted to a size range of 0.5 Rc.ltoreq.R.ltoreq.2 Rc, ba (Ti 0.7 Zr 0.3 )O 3 The seed single crystal is continuously grown inside the polycrystal, and thus a single crystal having the same composition as the polycrystal is produced. At this time, the grown single crystal had a size of 20X 20mm 2 The above.
By the steps of producing single crystals [ powder calcination process, sintering process of powder molded article (first heat treatment) and single crystal growth process (second heat treatment) ]The oxygen partial pressure in the atmosphere is regulated to regulate the oxygen vacancy content z, and the grown single crystal is subjected to heat treatment (a third heat treatment process), so that [ Pb ] is finally produced in the range of' 0.0.ltoreq.z.ltoreq.0.03 0.98- 1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (0.0≤x≤0.02；0<z.ltoreq.0.03).
For the piezoelectric single crystals, the oxygen partial pressure in the atmosphere in the composition (change in x) and the heat treatment process [ the powder calcination process, the sintering process of the powder molded article (first heat treatment), the single crystal growth process (second heat treatment), and the additional heat treatment after the single crystal growth process (third heat treatment) ] was adjusted, and thus various piezoelectric single crystals having "0<z.ltoreq.0.03 [ oxygen vacancy content ]" as shown in tables 5 and 6 were produced.
< example 4> production of piezoelectric Single Crystal containing oxygen vacancy 2
The same procedure as shown in example 3 was conducted to prepare a Pb-based alloy 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.35 (Mn 1/3 Nb 2/3 ) 0.05 Zr 0.25 Ti 0.35 ]O 3-z (x is more than or equal to 0.0 and less than or equal to 0.02[ donor content ]]The method comprises the steps of carrying out a first treatment on the surface of the Z is more than or equal to 0.0 and less than or equal to 0.0.03[ oxygen vacancy content ]]) A piezoelectric single crystal of the composition of (a).
Excess MgO and PbO were added during the synthesis of the powder so that the MgO-containing second phase and pore strengthening phase could be contained at 2% by volume. In addition, by the method of producing a single crystal [ powder calcination process, sintering process of powder molded article (first heat treatment process) and single crystal growth process (second heat treatment process) ]The oxygen partial pressure in the atmosphere is regulated to regulate the oxygen vacancy content z, and the grown single crystal is subjected to heat treatment (a third heat treatment process), so that [ Pb ] is finally produced in the range of' 0.0.ltoreq.z.ltoreq.0.03 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.35 (Mn 1/3 Nb 2/3 ) 0.05 Zr 0.25 Ti 0.35 ]O 3-z (0.0≤x≤0.02；0<z.ltoreq.0.03).
For the piezoelectric single crystals, the oxygen partial pressure in the atmosphere during the composition (change in x) and heat treatment [ powder calcination process, sintering process of powder molded article (first heat treatment), single crystal growth process (second heat treatment), and additional heat treatment after single crystal growth process (third heat treatment) ] was adjusted, and thus various piezoelectric single crystals satisfying "0<z.ltoreq.0.03 [ oxygen vacancy content ]" as shown in tables 7 and 8 were produced.
< Experimental example 5> evaluation 1 of dielectric and piezoelectric Properties related to piezoelectric Single Crystal shown in example 3
For [ Pb ] produced in said example 3 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.z.ltoreq.0.03), and evaluating dielectric and piezoelectric characteristics.
Specifically, for the production [ Pb ] 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.z.ltoreq.0.03) single crystal, x [ donor content ] measured by IEEE method using an impedance analyzer or the like]And z [ oxygen vacancy content ]]Dielectric constant and phase transition temperature T caused by variation of (C) c And T RT Piezoelectric charge constant, coercive electric field E c And an internal bias electric field E I The respective changes in the characteristics are shown in table 5 below.
[ Table 5 ]
From table 5 above, it was confirmed that in the case of (001) piezoelectric single crystal (x=0.01, z=0.0) (comparative example 5), the piezoelectric charge constant d 33 4457pC/N, a dielectric constant of 14678 and a dielectric loss tan delta of 1.0%.
In contrast, it was observed that the physical properties of piezoelectric single crystals are dependent on x [ donor content ]]And 0 (0)<z [ oxygen vacancy content ]]Is greatly changed. I.e. with x [ donor content ]]The dielectric constant and the piezoelectric charge constant increase with 0<z [ oxygen vacancy content ]]The dielectric constant and the piezoelectric charge constant continuously decrease, but the coercive electric field E C And an internal bias electric field E I And (3) increasing.
Thus, at x [ donor content ]]And z [ oxygen vacancy content ]]When the value of (a) exceeds a certain value (x.noteq.0.0 and z.noteq.0.0), the dielectric constant and the piezoelectric charge constant are kept similar to those shown in a general PMN-PT single crystal, and at the same time, the coercive electric field E C And an internal bias electric field E I Can be greatly increased. In particular, since the internal bias electric field E which is not present in a general PMN-PT single crystal can be induced sufficiently large I Therefore, a novel piezoelectric single crystal having a large resistance to the external environment can be developed.
< Experimental example 6> evaluation 2 of dielectric and piezoelectric Properties related to piezoelectric Single Crystal shown in example 3
[ Pb ] as shown in said example 3 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (0.0≤x≤0.02；0<z.ltoreq.0.03), fig. 7 shows a piezoelectric single crystal satisfying the conditions of x=0.01 and z=0.0 (comparative example 5), fig. 8 shows a piezoelectric single crystal satisfying the conditions of x=0.01 and z=0.005 (examples 3 to 3), and fig. 9 shows a piezoelectric single crystal satisfying the conditions of x=0.01 and z=0.01 (examples 3 to 4).
At this time, for each satisfying the condition "x=0.01" shown in fig. 8; z=0.005 (examples 3-3) "and the condition" x=0.01 "shown in fig. 9; z=0.01 (examples 3 to 4) ", after the end of the single crystal growth process, the third heat treatment process was performed again, and the atmosphere [ the magnitude of the oxygen partial pressure ] in the third heat treatment process was adjusted, so that the" z [ oxygen vacancy content ] "was increased.
Further, the dielectric constant, piezoelectric charge constant, coercive electric field E of the piezoelectric single crystal after the third heat treatment were measured by the IEEE method using an impedance analyzer or the like C And an internal bias electric field E I The respective changes in the characteristics are shown in table 6 below.
[ Table 6 ]
/>
As shown in table 6 above, after the end of the single crystal growth process, the third heat treatment was performed again, and it was observed that the physical properties of the piezoelectric single crystal and the oxygen vacancy content z were greatly changed simultaneously with the change in the atmosphere [ the magnitude of the oxygen partial pressure ] during the heat treatment.
As the partial pressure of oxygen in the atmosphere decreases during the heat treatment, the dielectric constant and piezoelectric charge constant decrease continuously, but the coercive electric field E C And an internal bias electric field E I And (3) increasing. Furthermore, with x [ donor content ]]And z [ oxygen vacancy content ]]The value of (c) becomes larger and the effect tends to increase more.
Thus, when the composition containing x [ donor content ] is produced under conditions of low partial pressure of oxygen]And z [ oxygen vacancy content ]]The dielectric constant and the piezoelectric charge constant remain similar to those shown in a general PMN-PT single crystal whileCoercive electric field E C And an internal bias electric field E I Can be greatly increased.
Since the atmosphere [ the partial pressure of oxygen ] in the heat treatment process can be regulated]An internal bias electric field E sufficiently large to be absent in inducing a general PMN-PT single crystal I Therefore, a novel piezoelectric single crystal having a large resistance to the external environment can be developed.
Based on the result, for [ Pb ] 0.98-1.5x Sr 0.02 Sm x ][(Mg 1/3 Nb 2/3 ) 0.35 Zr 0.30 Ti 0.35 ]O 3-z (0.0≤x≤0.02；0<z.ltoreq.0.03), in adjusting "x [ donor content ]]"" z [ oxygen vacancy content ]]"and" x/z ratio "and simultaneously adjusting the atmosphere [ the magnitude of partial pressure of oxygen ] during the heat treatment]In the case of (2), the piezoelectric charge constant and coercive electric field E of the produced piezoelectric single crystal were confirmed C And an internal bias electric field E I May be most suitable. Thus, it is contained in a specific range (0<z.ltoreq.0.03) is characterized in that they stably maintain their high-voltage electric characteristics against changes in the external environment, unlike those shown in conventional general PMN-PT or PIN-PMN-PT single crystals.
Experimental example 7> evaluation 1 of dielectric and piezoelectric characteristics related to piezoelectric single crystal shown in example 4
For [ Pb ] produced in said example 4 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.35 (Mn 1/3 Nb 2/3 ) 0.05 Zr 0.25 Ti 0.35 ]O 3-z (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.z.ltoreq.0.03), and evaluating dielectric and piezoelectric characteristics.
For Pb produced 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.35 (Mn 1/3 Nb 2/3 ) 0.05 Zr 0.25 Ti 0.35 ]O 3-z (0.0.ltoreq.x.ltoreq.0.02; 0.0.ltoreq.z.ltoreq.0.03) single crystal, x [ donor content ] measured by IEEE method using an impedance analyzer or the like]And z [ oxygen vacancy content ]]Dielectric constant and phase transition temperature T caused by variation of (C) c And T TRT Piezoelectric charge constant, coercive electric field E c And an internal bias electric field E I The respective changes in the characteristics are shown in table 7 below.
[ Table 7 ]
As shown in table 7, in the case of (001) piezoelectric single crystal (x=0.01, z=0.0) (comparative example 6), the piezoelectric charge constant d 33 The dielectric constant was 6920, and the dielectric loss tan. Delta. Was 0.3%, which was 1760 pC/N.
In contrast, it was observed that the physical properties of piezoelectric single crystals are dependent on x [ donor content ]]And 0 (0)<z [ oxygen vacancy content ] ]Is greatly changed. That is, it was confirmed that the dielectric constant and the piezoelectric charge constant were dependent on x [ donor content ]]With an increase in dielectric constant and piezoelectric charge constant increasing with an increase of 0<z [ oxygen vacancy content ]]Continuously decreasing with increasing coercive electric field E C And an internal bias electric field E I And (3) increasing.
Thus, at x [ donor content ]]And z [ oxygen vacancy content ]]When the value of (a) exceeds a certain value (x.noteq.0.0 and z.noteq.0.0), the dielectric constant and the piezoelectric charge constant are kept similar to those shown in a general PMN-PT single crystal, and at the same time, the coercive electric field E C And an internal bias electric field E I Can be greatly increased. In particular, since the internal bias electric field E which is not present in a general PMN-PT single crystal can be induced sufficiently large I Therefore, a novel piezoelectric single crystal having a large resistance to the external environment can be developed.
< Experimental example 8> evaluation 2 of dielectric and piezoelectric Properties related to piezoelectric Single Crystal shown in example 4
For meeting based on Pb 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.35 (Mn 1/3 Nb 2/3 ) 0.05 Zr 0.25 Ti 0.35 ]O 3-z Single crystals satisfying the conditions of "x=0.01 and z=0.005" and "x=0.01 and z=0.01" in single crystals having a composition of (0.0.0.ltoreq.x.ltoreq.0.02; 0.0.0.ltoreq.z.ltoreq. 0.0.03), during the single crystal growth processAfter the completion, the third heat treatment process is carried out again, and the atmosphere [ the partial pressure of oxygen ] in the third heat treatment process is regulated ]So that "z [ oxygen vacancy content ]]"increase". Measuring dielectric constant, piezoelectric charge constant, coercive electric field E of the piezoelectric single crystal after the third heat treatment by IEEE method using an impedance analyzer or the like C And an internal bias electric field E I The respective changes in the characteristics are shown in table 8 below.
[ Table 8 ]
As shown in Table 8, after the end of the single crystal growth process, the third heat treatment was again performed, and physical properties of the piezoelectric single crystal and the oxygen vacancy content [ z ] were observed]With atmosphere during heat treatment [ size of partial pressure of oxygen ]]Is greatly changed. As the partial pressure of oxygen decreases during the heat treatment, the dielectric constant and piezoelectric charge constant decrease continuously, but the coercive electric field E C And an internal bias electric field E I And (3) increasing.
With x [ donor content ]]And z [ oxygen vacancy content ]]The value of (c) becomes larger and the effect tends to increase more. Thus, when the composition containing x [ donor content ] is produced under conditions of low partial pressure of oxygen]And z [ oxygen vacancy content ]]The dielectric constant and the piezoelectric charge constant remain similar to those shown in a general PMN-PT single crystal while the coercive electric field E C And an internal bias electric field E I Can be greatly increased. Since the atmosphere [ the partial pressure of oxygen ] in the heat treatment process can be regulated ]Sufficiently large to induce an internal bias electric field E that is not present in a general PMN-PT single crystal I Therefore, a novel piezoelectric single crystal having a large resistance to the external environment can be developed.
Based on the result, for [ Pb ] 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.35 (Mn 1/3 Nb 2/3 ) 0.05 Zr 0.25 Ti 0.35 ]O 3-z (0.0≤x≤0.02；0<z.ltoreq.0.03), in adjusting "x [ donor content ]]"" z [ oxygen vacancy content ]]"and" x/z ratio "and at the same time adjusting the atmosphere [ the magnitude of partial pressure of oxygen ] during the heat treatment]In the case of (2), the piezoelectric charge constant and coercive electric field E of the produced piezoelectric single crystal were confirmed C And an internal bias electric field E I May be most suitable. Thus, included in a specific range (0<z.ltoreq.0.02) is characterized in that they stably maintain their high-voltage electric characteristics against changes in the external environment, unlike those shown in conventional general PMN-PT or PIN-PMN-PT single crystals.
< Experimental example 9> observation of changes in internal bias electric field due to temperature changes
Using a general PMN-30PT piezoelectric monocrystal and [ Pb ] shown in example 2 0.98-1.5x Sr 0.02 La x ][(Mg 1/ 3 Nb 2/3 ) 0.35 (Mn 1/3 Nb 2/3 ) 0.05 Zr 0.25 Ti 0.35 ]O 3-z A measurement sample having a size of "(001) 4×4×0.5 (T) mm" was produced from a piezoelectric single crystal satisfying the conditions of "x=0.01 and z=0.0" (comparative example 6) and "x=0.01 and z=0.02" (examples 4 to 5), and the coercive electric field E was plotted against the electric field polarization diagram based on the internal bias electric field C And an internal bias electric field E I The magnitudes of (2) are compared with each other.
FIG. 10 is a diagram showing the [ Pb ] of the present invention 0.98-1.5x Sr 0.02 La x ][(Mg 1/3 Nb 2/3 ) 0.35 (Mn 1/3 Nb 2/3 ) 0.05 Zr 0.25 Ti 0.35 ]O 3-z A graph of changes in polarization-electric fields in relation to the piezoelectric single crystal and the general PMN-30PT piezoelectric single crystal, respectively, satisfying the condition of x=0.01 and z=0.0 (comparative example 6) and the condition of x=0.01 and z=0.02 (examples 4 to 5).
As a result, the coercive electric field and the internal bias electric field of the general PMN-30PT piezoelectric single crystal at 25℃were 2.5 and 0.0kV/cm, respectively [ no internal bias electric field ], and the coercive electric field and the internal bias electric field of the piezoelectric single crystal satisfying the condition "x=0.01 and z=0.0" (comparative example 6) were 4.4 and 1.0kV/cm, respectively, and were relatively high. In the case of a piezoelectric single crystal in which the value of z is increased more by the condition "x=0.01 and z=0.02" (examples 4 to 5), the coercive electric field and the internal bias electric field are 5.6 and 3.4kV/cm, respectively, and are greatly increased. Based on this result, it was found that the coercive electric field and the internal bias electric field increased in proportion to the increased oxygen vacancy content inside the piezoelectric single crystal.
As described above, with respect to the composition of the piezoelectric single crystal, when x [ donor content ] and z [ oxygen vacancy content ] are adjusted while adjusting the atmosphere [ magnitude of partial pressure of oxygen ] during the heat treatment, z [ oxygen vacancy content ] which is not present in a general PMN-PT single crystal can be induced sufficiently large.
As described above, although the present invention has been described in detail with respect to only the specific examples described, it should be understood that various changes and modifications may be made by those having ordinary skill in the art within the scope of the technical concept of the present invention and such changes and modifications fall naturally under the appended claims.
Claims (25)
1. A structure with perovskite type ([ A ] containing internal bias electric field][B]O 3 ) Which satisfies the physical properties listed in the following items (1) to (4):
(1) Dielectric constant K 3 T 4000 to 15000;
(2) Piezoelectric charge constant d 33 1400 to 6000pC/N;
(3) Coercive electric field E C 3.5 to 12kV/cm; and
(4) Internal bias electric field E I From 0.5 to 3.0kV/cm.
2. The piezoelectric single crystal according to claim 1, wherein the physical properties are maintained at a temperature of 20 ℃ to 80 ℃.
3. The piezoelectric single crystal according to claim 1, wherein the piezoelectric single crystal having a perovskite structure is represented by a composition formula of the following chemical formula 1:
chemical formula 1
[A 1-(a+1.5b) B a C b ][(MN) 1-x-y (L) y Ti x ]O 3
In the formula, A represents Pb or Ba,
b represents at least one or more elements selected from the group consisting of Ba, ca, co, fe, ni, sn and Sr,
c represents one or more elements selected from the group consisting of Co, fe, bi, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb and Lu,
L represents a single form composed of one selected from Zr or Hf, or a mixed form thereof,
m represents at least one or more elements selected from the group consisting of Ce, co, fe, in, mg, mn, ni, sc, yb and Zn,
n represents at least one or more elements selected from the group consisting of Nb, sb, ta and W, and
a. b, x and y represent 0<a.ltoreq.0.10, 0<b.ltoreq.0.05, 0.05.ltoreq.x.ltoreq.0.58 and 0.05.ltoreq.y.ltoreq.0.62, respectively.
4. The piezoelectric single crystal according to claim 1, wherein the piezoelectric single crystal having a perovskite structure is represented by a composition formula of the following chemical formula 2:
chemical formula 2
[A 1-(a+1.5b) B a C b ][(MN) 1-x-y (L) y Ti x ]O 3-z
In the case of the formula (I) described above,
a represents Pb or Ba, and the component A is represented,
b represents at least one or more elements selected from the group consisting of Ba, ca, co, fe, ni, sn and Sr,
c represents one or more elements selected from the group consisting of Co, fe, bi, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb and Lu,
l represents a single form composed of one selected from Zr or Hf, or a mixed form thereof,
m represents at least one or more elements selected from the group consisting of Ce, co, fe, in, mg, mn, ni, sc, yb and Zn,
n represents at least one or more elements selected from the group consisting of Nb, sb, ta and W, and
a. b, x, y and z represent 0<a.ltoreq.0.10, 0<b.ltoreq.0.05, 0.05.ltoreq.x.ltoreq.0.58, 0.05.ltoreq.y.ltoreq.0.62 and 0<z.ltoreq.0.02, respectively.
5. The piezoelectric single crystal according to claim 3 or 4, wherein when L represents a mixed form, the piezoelectric single crystal is represented by a composition formula of chemical formula 3 or chemical formula 4:
chemical formula 3
[A 1-(a+1.5b) B a C b ][(MN) 1-x-y (Zr 1-w ,Hf w ) y Ti x ]O 3
Chemical formula 4
[A 1-(a+1.5b) B a C b ][(MN) 1-x-y( Zr 1-w ,Hf w ) y Ti x ]O 3-z
Wherein A, B, C, M, N, a, b, x, y and z are the same as in chemical formula 1 or chemical formula 2, but w represents 0.01.ltoreq.w.ltoreq.0.20.
6. The piezoelectric single crystal according to claim 3 or 4, wherein in the formula, a and b represent 0.01.ltoreq.a.ltoreq.0.10, 0.01.ltoreq.b.ltoreq.0.05, respectively.
7. The piezoelectric single crystal according to claim 3 or 4, wherein in the formula, a and b represent a/b.gtoreq.2.
8. The piezoelectric single crystal according to claim 3 or 4, wherein in the formula, x and y represent 0.10.ltoreq.x.ltoreq.0.58 and 0.10.ltoreq.y.ltoreq.0.62, respectively.
9. The piezoelectric single crystal according to claim 3 or 4, wherein the single crystal has a porosity of 0.5% by volume or more inside.
10. The piezoelectric single crystal according to claim 3 or 4, wherein a composition gradient inside the single crystal with respect to the piezoelectric single crystal is formed in a range of 0.2mol% to 0.5 mol%.
11. The piezoelectric single crystal according to claim 3 or 4, wherein x and y belong to a range within 10mol% of the composition of a quasi-homotype phase boundary between a rhombohedral phase and a tetragonal phase.
12. The piezoelectric single crystal according to claim 3 or 4, wherein x and y belong to a range within 5mol% of the composition of a quasi-homotype phase boundary between a rhombohedral phase and a tetragonal phase.
13. The piezoelectric single crystal according to claim 3 or 4, wherein the piezoelectric single crystal exhibits a curie temperature T C At the same time, the phase transition temperature T between the rhombohedral phase and the tetragonal phase is more than 180 DEG C RT Is above 100deg.C.
14. The piezoelectric single crystal according to claim 3 or 4, wherein the piezoelectric single crystal exhibits a longitudinal electromechanical coupling coefficient k 33 Is 0.85 or more.
15. A method for producing a piezoelectric single crystal, comprising:
a step (a) of reducing the number density of abnormal grains (i.e., the number of abnormal grains per unit area) by adjusting the average size of matrix grains having a polycrystal constituting the composition of the piezoelectric single crystal of claim 3 or 4;
and (b) growing the abnormal crystal grains by heat-treating the polycrystal having a reduced number density of abnormal crystal grains obtained through the step (a), wherein a powder molded article is obtained in such a manner that a powder based on a composition constituting the piezoelectric single crystal is calcined at a temperature of less than 800 ℃ to 900 ℃, and a first heat-treating process of sintering the powder molded article and a second heat-treating process required at the time of the single crystal growth are performed.
16. The method of claim 15, wherein the first and second heat treatment processes are performed at 900 ℃ to 1300 ℃ for 1 to 100 hours.
17. The method of claim 16, wherein the heat treatment is performed at a ramp rate of 1 to 20 ℃/min.
18. The method of claim 17, wherein the coercive electric field E is controlled according to conditions of oxygen partial pressure during the heat treatment C And an internal bias electric field E I Is a physical property of (a) a (b).
19. The method of claim 18, wherein the coercive electric field E C And an internal bias electric field E I Is realized to increase according to conditions of decreasing oxygen partial pressure.
20. The method of claim 15, wherein a third heat treatment process is further performed after the single crystal growth is completed.
21. The method of claim 20, wherein the third heat treatment process is performed at 600 ℃ to 1300 ℃ for 0.1 to 100 hours.
22. The method of claim 20, wherein the oxygen vacancy content (0<z +.0.02) is adjusted during the third heat treatment by conditions of partial pressure of oxygen.
23. A piezoelectric body comprising only the piezoelectric single crystal according to any one of claims 1 to 14, or the piezoelectric single crystal and a polymer mixed.
24. A piezoelectric application part and a dielectric application part using the piezoelectric substance containing the piezoelectric single crystal according to claim 1.
25. The piezoelectric and dielectric application of claim 24, wherein the piezoelectric and dielectric application is any one selected from the group consisting of an ultrasonic transducer, a piezoelectric actuator, a piezoelectric sensor, a dielectric capacitor, an electric field generating transducer, and an electric field vibration generating transducer.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR10-2020-0173613 | 2020-12-11 | ||
| KR10-2020-0173711 | 2020-12-11 | ||
| KR1020210171669A KR102632993B1 (en) | 2020-12-11 | 2021-12-03 | Piezoelectric single crystal, manufacturing method thereof and use for piezoelectric and dielectric articles using the same |
| KR10-2021-0171669 | 2021-12-03 | ||
| KR10-2021-0171667 | 2021-12-03 | ||
| PCT/KR2021/018539 WO2022124794A1 (en) | 2020-12-11 | 2021-12-08 | Piezoelectric single crystal including internal electric field, method for manufacturing same, and piezoelectric and dielectric application components using same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116724687A true CN116724687A (en) | 2023-09-08 |
Family
ID=87873876
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202180082485.1A Pending CN116724687A (en) | 2020-12-11 | 2021-12-08 | Piezoelectric single crystal including internal electric field, method of manufacturing the same, and piezoelectric and dielectric application member using the same |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116724687A (en) |
-
2021
- 2021-12-08 CN CN202180082485.1A patent/CN116724687A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100743614B1 (en) | Piezoelectric Single Crystal and Method of Production of Same, Piezoelectric Element, and Dielectric Element | |
| Luo et al. | Dielectric, ferroelectric and piezoelectric properties of MnO2-doped Pb (Yb1/2Nb1/2) O3-Pb (Zr, Ti) O3 ceramics | |
| Perumal et al. | Investigations on electrical and energy storage behaviour of PZN-PT, PMN-PT, PZN–PMN-PT piezoelectric solid solutions | |
| WO2010079838A1 (en) | Piezoelectric material | |
| US11486055B2 (en) | Polar nanoregions engineered relaxor-PbTiO3 ferroelectric crystals | |
| Go et al. | Improvement of piezoelectricity of (Na, K) Nb-based lead-free piezoceramics using [001]-texturing for piezoelectric energy harvesters and actuators | |
| KR101779899B1 (en) | Piezoelectric multilayer actuator with piezoelectric single crystal | |
| JP6185441B2 (en) | Piezoelectric single crystal and piezoelectric single crystal element | |
| Li et al. | Dielectric, ferroelectric and electric field-induced strain properties of (Pb1-xBax)(Zr1-yTiy) O3 ceramics | |
| KR101368080B1 (en) | Piezoelectric material, piezoelectric element, liquid discharge head, ultrasonic motor, and dust cleaning device | |
| Yoon et al. | Electric-field-induced strain and piezoelectric properties near the morphotropic phase boundary of Pb (Mg 1/3 Nb 2/3) O 3–PbZrO 3–PbTiO 3 ceramics | |
| CN116724687A (en) | Piezoelectric single crystal including internal electric field, method of manufacturing the same, and piezoelectric and dielectric application member using the same | |
| KOBUNE et al. | Effects of MnO2 addition on piezoelectric and ferroelectric properties of PbNi1/3Nb2/3O3-PbTiO3-PbZrO3 ceramics | |
| US20230329120A1 (en) | Piezoelectric single crystal including internal electric field, method for manufacturing same, and piezoelectric and dielectric application components using same | |
| KR102632993B1 (en) | Piezoelectric single crystal, manufacturing method thereof and use for piezoelectric and dielectric articles using the same | |
| KR102663619B1 (en) | Piezoelectric single crystal including internal bias electric field, manufacturing method thereof and use for piezoelectric and dielectric articles using the same | |
| CN116569675A (en) | Piezoelectric single crystal, method for producing the same, and piezoelectric and dielectric application member using the same | |
| Antonova et al. | Structure and properties of hot-pressed Pb (Lu 1/2 Nb 1/2) O 3-PbTiO 3 binary system ceramics | |
| KR102664918B1 (en) | Piezoelectric single crystal, manufacturing method thereof and use for piezoelectric and dielectric articles using the same | |
| CN116671281A (en) | Piezoelectric single crystal-polycrystalline ceramic composite material, method for producing the same, and piezoelectric and dielectric application member using the same | |
| Ashutosh et al. | Stabilities and piezoelectric properties of morphotropic phase boundary composition 0.2 Pb (Mg1/3Nb2/3) O3–0.38 PbZrO3–0.42 PbTiO3 ternary piezoceramics | |
| US20230247908A1 (en) | Piezoelectric single crystal-polycrystalline ceramic composite, preparation method therefor, and piezoelectric and dielectric application components using same | |
| KR102632987B1 (en) | Piezoelectric single crystal-matrix grains composites, manufacturing method thereof and use for piezoelectric and dielectric articles using the same | |
| US20230399769A1 (en) | Piezoelectric single crystal, fabrication method therefor, and piezoelectric and dielectric application parts using same | |
| KR102623532B1 (en) | Modifying method for single crystal of lead-metal compound |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |