CN110723968A - Microwave dielectric ceramic with high dielectric constant and preparation method thereof - Google Patents

Microwave dielectric ceramic with high dielectric constant and preparation method thereof Download PDF

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CN110723968A
CN110723968A CN201911076671.5A CN201911076671A CN110723968A CN 110723968 A CN110723968 A CN 110723968A CN 201911076671 A CN201911076671 A CN 201911076671A CN 110723968 A CN110723968 A CN 110723968A
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biscuit
dielectric ceramic
microwave dielectric
mixture
tio
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何磊
龚毅辉
徐海维
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Suzhou Boom High Purity Materials Technology Co Ltd
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Suzhou Boom High Purity Materials Technology Co Ltd
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Abstract

The invention relates to a microwave dielectric ceramic with high dielectric constant and a preparation method thereof, wherein the method comprises the following steps: s1, mixing raw material CaCO3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3According to each case to CaCO3‑Li2CO3‑Sm2O3‑TiO2‑MgO‑Nb2O5‑Al2O3Weighing and proportioning the chemical components, putting the proportioned mixture into a ball mill, and ball-milling the particle size of the mixture to a preset particle size; s2, drying and screening the ball-milled mixture; s3, adding a binder into the mixture dried and screened in the step S2, and granulating; s4, drying the granulating material obtained in the S3 stepPressing and molding to obtain a biscuit, removing the glue from the biscuit and sintering to obtain the microwave dielectric ceramic; according to the invention, after the mixture of the raw materials is ball-milled to a certain size, the medium ceramic is prepared by completing a sintering process, compared with the traditional preparation method, the preparation method saves a high-temperature calcination process and a grinding and mixing process for multiple times, reduces the production cost, avoids powder pollution in the multiple grinding processes in the traditional preparation method, and effectively improves the quality factor.

Description

Microwave dielectric ceramic with high dielectric constant and preparation method thereof
Technical Field
The invention relates to the technical field of microwave dielectric ceramics, in particular to a microwave dielectric ceramic with high dielectric constant and a preparation method thereof.
Background
Microwave Dielectric Ceramics (MWDC for short) is applied to Microwave frequency band (300 MHz-300 GHz) circuits as a Dielectric material and completes one or more functions, is widely used as components and parts such as resonators, filters, Dielectric antennas, Dielectric waveguide loops and the like in modern communication, is a key basic material of modern communication technology, has very important application in the aspects of portable mobile phones, automobile phones, cordless phones, television satellite receivers, military radars and the like, and plays an increasingly greater role in the miniaturization and integration processes of modern communication tools.
Since the last 70 th century, large-scale development work on dielectric ceramic materials began, and the dielectric ceramic applied to the microwave frequency band generally needs to satisfy the following three conditions: (1) the dielectric constant is suitable for miniaturization of the device (the size of a dielectric component is inversely proportional to the square root of the dielectric constant epsilon r); (2) the high quality factor Q is used for reducing loss, and Q multiplied by f is generally required to be more than or equal to 5000GHz (wherein f is resonance frequency); (3) and the temperature coefficient of the frequency is stable, so that the temperature stability of the device is ensured.
The current pursuit of intelligent wearable equipment leads to the miniaturization of microwave devices, and higher dielectric constant(s) ((>90) The microwave dielectric ceramics of (2) mainly have the following three types at present: (1) based on BaO-Ln2O3-TiO2(wherein Ln is La, Sm or Nd rare earth element); (2) pb-based perovskite-based systems; (3) based on CaTiO3-Li0.5Ln0.5TiO3The perovskite solid solution structure system (wherein Ln is La, Sm or Nd rare earth element);
wherein, in order to increase BaO-Ln2O3-TiO2The dielectric constant and quality factor of tungsten bronze structure system (wherein Ln is La, Sm or Nd rare earth element) usually introduces Bi3+ and other noble metal elements, so that the raw material cost is increased, Bi is easy to volatilize and pollute the environment during high-temperature sintering of ceramics, the production cost is increased, and in addition, the Pb-based perovskite system contains toxic element Pb, so that the system is not suitable for the requirement of modern sustainable development, so that the system is based on CaTiO3-Li0.5Ln0.5TiO3The perovskite solid solution structure (CLLT for short) has the characteristics of relatively low raw material cost and environmental protection requirement, and becomes the mainstream high dielectric constant at present, and researches show that the dielectric constant of the system can reach up to 120.
For the CLLT system, CaTiO is used3Positive temperature coefficient of (5) and Li0.5Ln0.5TiO3The negative temperature coefficient of the ceramic is compounded to form a solid solution to obtain practical ceramic with a near-zero temperature coefficient, and the common preparation method adopts a solid-phase synthesis technology, mainly CaCO3、Li2CO3、Ln2O3And TiO2Firstly, respectively synthesizing CaTiO serving as raw materials3And Li0.5Ln0.5TiO3The precursor powder is mixed and ground for the second time according to a certain proportion to a certain granularity, then a proper ceramic forming technology is selected to obtain a biscuit, and the biscuit is subjected to binder removal and sintering to obtain corresponding ceramic, wherein modifiers such as Ba2+, Sr2+, Mn4+ and the like are added in the process of synthesizing the precursor powder or mixing and grinding for the second time to improve the CLLT quality factor.
Therefore, the preparation method adopts the steps of firstly mixing, grinding and calcining the respective raw materials respectively to synthesize CaTiO3And Li0.5Ln0.5TiO3The precursor powder is prepared by mixing, grinding, molding, binder removal and sintering the two synthetic powders and some trace additives for the second time, and the preparation process is complicated, high in process cost and low in reliability.
Based on the above analysis, it is an urgent need to solve the problems of the art to improve the preparation process and the performance of the microwave dielectric ceramic with high dielectric constant.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present invention is to provide a microwave dielectric ceramic with a high dielectric constant and a preparation method thereof, wherein a mixture of raw materials is ball-milled to a certain size, and then is directly molded, de-glued and sintered to prepare the microwave dielectric ceramic, so that the preparation process is saved, the production cost is reduced, powder pollution in multiple grinding processes is avoided, and the quality factor of the dielectric ceramic is effectively improved.
In order to solve the problems, the invention provides a preparation method of microwave dielectric ceramic with high dielectric constant, which comprises the following steps:
s1, mixing raw material CaCO3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3According to each case to CaCO3-Li2CO3-Sm2O3-TiO2-MgO-Nb2O5-Al2O3Weighing and proportioning the chemical components, putting the proportioned mixture into a ball mill, and ball-milling the particle size of the mixture to a preset particle size;
s2, drying and screening the mixture after ball milling;
s3, adding a binder into the mixture dried and screened in the S2 step for granulation;
and S4, performing dry pressing forming on the granulated material obtained in the step S3 to obtain a biscuit, and performing binder removal and sintering on the biscuit to obtain the microwave dielectric ceramic.
Further, CaCO in the mixture3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3The molar mass ratio of (A) to (B) is 16: 9: 12: 63-x: x/3: x/3: y, x is 0.01-0.05, and y is 0.008-0.02.
Further, the preset particle size is 1-1.5 um.
Further, the step S4 of preparing the microwave dielectric ceramic by de-gumming and sintering the biscuit includes:
placing the biscuit in a high-temperature furnace, and slowly heating to discharge the glue;
placing the biscuit subjected to binder removal in a high-temperature furnace for slow sintering;
and cooling the sintered biscuit to room temperature to obtain the microwave dielectric ceramic.
Further, the specific process of placing the biscuit in a high-temperature furnace for slowly heating up for removing the glue is as follows: the temperature is raised from 50 ℃ to 900 ℃ at a rate of 1-2 ℃/min.
Further, the specific process of slowly sintering the biscuit in a high temperature furnace after the binder removal comprises the following steps: raising the temperature from 800 ℃ to 1170-1210 ℃ at the temperature raising rate of 2-3 ℃/min, and preserving the temperature for 3-4h at 1170-1210 ℃.
Further, the forming pressure of the dry pressing forming in the step S4 is 80-120 MPa.
Further, the main chemistry of the adhesive is polyvinyl alcohol and polyethylene glycol, and the mass percentage of the polyvinyl alcohol and the polyethylene glycol is 1.2-1.5% and 0.3-0.6%.
The invention also discloses a microwave dielectric ceramic with high dielectric constant, which is prepared by any one of the preparation methods.
Due to the technical scheme, the invention has the following beneficial effects:
1) according to the microwave dielectric ceramic with the high dielectric constant and the preparation method thereof, after the mixture of the raw materials is ball-milled to a certain size, the microwave dielectric ceramic is prepared by direct molding, binder removal and sintering, so that the preparation and secondary grinding processes of precursor powder are omitted, the production cost is greatly reduced, the powder pollution in the multiple grinding processes is avoided, and the quality factor of the dielectric ceramic is effectively improved;
2) the invention relates to a microwave dielectric ceramic with high dielectric constant and a preparation method thereof, which adds MgO and Nb by reasonable raw material proportion2O5To (Mg)1/3Nb2/3)4+Composite ion replacement of Ti4+Shrinking [ TiO ] in CLST crystal structure]6The octahedron enables the temperature coefficient to approach zero so as to meet the practical requirement;
3) the invention relates to a microwave dielectric ceramic with high dielectric constant and a preparation method thereof, wherein Al is added according to a reasonable raw material ratio2O3Can play a pinning effect in the ceramic sintering process, and avoids Li in the raw materials2CO3The liquid phase formed by melting at about 600 ℃ causes the pores in the biscuit to be sealed in the ceramic body by the crystal grains, the process difficulty of obtaining high-density ceramic is difficult, and the reaction sintering CaCO is improved3-Li2CO3-Sm2O3-TiO2Quality factor of microwave dielectric ceramic.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiment or the prior art will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a flow chart of a method for preparing a high dielectric constant microwave dielectric ceramic according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic may be included in at least one implementation of the invention. In the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", "top", "bottom", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein.
Example one
The embodiment provides a method for preparing a microwave dielectric ceramic with a high dielectric constant, as shown in fig. 1, which includes the following steps:
s1, mixing raw material CaCO3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3According to each case to CaCO3-Li2CO3-Sm2O3-TiO2-MgO-Nb2O5-Al2O3Weighing and proportioning the chemical components, putting the proportioned mixture into a ball mill, and ball-milling the particle size of the mixture to a preset particle size;
s2, drying and screening the mixture after ball milling;
s3, adding a binder into the mixture dried and screened in the S2 step for granulation;
and S4, performing dry pressing forming on the granulated material obtained in the step S3 to obtain a biscuit, and performing binder removal and sintering on the biscuit to obtain the microwave dielectric ceramic.
In particular CaCO in the mixture3：Li2CO3：Sm2O3：TiO2：MgO：Nb2O5：Al2O3The molar mass ratio of (A) to (B) is 16: 9: 12: 63-x: x/3: x/3: y, x is 0.01-0.05, and y is 0.008-0.02.
Preferably, x is 0.01 and y is 0.008.
Specifically, the microwave dielectric ceramic is prepared from CaCO3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3MgO and Nb are added according to a reasonable raw material ratio2O5To (Mg)1/3Nb2/3)4+Composite ion replacement of Ti4+Shrink CaCO3-Li2CO3-Sm2O3-TiO2In crystal structure of [ TiO ]]6The octahedron enables the temperature coefficient to approach zero so as to meet the practical requirement; al is added by reasonable raw material proportion2O3Can play a pinning effect in the ceramic sintering process, and avoids Li in the raw materials2CO3The liquid phase formed by melting at about 600 ℃ causes the pores in the biscuit to be sealed in the ceramic body by the crystal grains, the process difficulty of obtaining high-density ceramic is difficult, and the reaction sintering CaCO is improved3-Li2CO3-Sm2O3-TiO2Quality factor of microwave dielectric ceramic.
Specifically, the preset particle size is 1-1.5 um.
Specifically, the step S4 of preparing the microwave dielectric ceramic by de-gumming and sintering the biscuit includes:
placing the biscuit in a high-temperature furnace, and slowly heating to discharge the glue;
placing the biscuit subjected to binder removal in a high-temperature furnace for slow sintering;
and cooling the sintered biscuit to room temperature to obtain the microwave dielectric ceramic.
Further, the specific process of placing the biscuit in a high-temperature furnace for slowly heating up for removing the glue is as follows: the temperature is raised from 50 ℃ to 900 ℃ at a rate of 1-2 ℃/min.
Further, the specific process of slowly sintering the biscuit in a high temperature furnace after the binder removal comprises the following steps: the temperature is raised from 800 ℃ to 1210 ℃ at the temperature raising rate of 2-3 ℃/min, and the temperature is kept for 3h at 1210 ℃.
Further, the cooling mode in the microwave dielectric ceramic obtained by cooling the sintered biscuit to room temperature is an on-line cooling mode.
Further, the forming pressure of the dry pressing forming in the step S4 is 80-120 MPa.
Preferably, the forming pressure for dry press forming in the S4 step is 80 MPa.
Further, the main chemistry of the adhesive is polyvinyl alcohol and polyethylene glycol, and the mass percentage of the polyvinyl alcohol and the polyethylene glycol is 1.2-1.5% and 0.3-0.6%.
Preferably, the main chemistry of the adhesive is polyvinyl alcohol and polyethylene glycol, and the mass percentage of the polyvinyl alcohol and the polyethylene glycol is 1.2% and 0.3%.
The embodiment also provides a microwave dielectric ceramic with high dielectric constant, which comprises the following main chemical components: CaCO3-Li2CO3-Sm2O3-TiO2-MgO-Nb2O5-Al2O3，
Wherein, CaCO3：Li2CO3：Sm2O3：TiO2：MgO：Nb2O5：Al2O3The molar mass ratio of (A) to (B) is 16: 9: 12: 63-x: x/3: x/3: y, x is 0.01 and y is 0.008.
Example two
The second embodiment provides a method for preparing a microwave dielectric ceramic with a high dielectric constant, as shown in fig. 1, which includes the following steps:
s1, mixing raw material CaCO3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3According to each case to CaCO3-Li2CO3-Sm2O3-TiO2-MgO-Nb2O5-Al2O3Weighing and proportioning the chemical components, putting the proportioned mixture into a ball mill, and ball-milling the particle size of the mixture to a preset particle size;
s2, drying and screening the mixture after ball milling;
s3, adding a binder into the mixture dried and screened in the S2 step for granulation;
and S4, performing dry pressing forming on the granulated material obtained in the step S3 to obtain a biscuit, and performing binder removal and sintering on the biscuit to obtain the microwave dielectric ceramic.
In particular CaCO in the mixture3：Li2CO3：Sm2O3：TiO2：MgO：Nb2O5：Al2O3The molar mass ratio of (A) to (B) is 16: 9: 12: 63-x: x/3: x/3: y, x is 0.01-0.05, and y is 0.008-0.02.
Preferably, x is 0.05 and y is 0.02.
Specifically, the preset particle size is 1-1.5 um.
Specifically, the step S4 of preparing the microwave dielectric ceramic by de-gumming and sintering the biscuit includes:
placing the biscuit in a high-temperature furnace, and slowly heating to discharge the glue;
placing the biscuit subjected to binder removal in a high-temperature furnace for slow sintering;
and cooling the sintered biscuit to room temperature to obtain the microwave dielectric ceramic.
Further, the specific process of placing the biscuit in a high-temperature furnace for slowly heating up for removing the glue is as follows: the temperature is increased from 50 ℃ to 900 ℃ at the temperature increase rate of 1-2 ℃/min.
Further, the specific process of slowly sintering the biscuit in a high temperature furnace after the binder removal comprises the following steps: heating the temperature from 800 ℃ to 1170 ℃ at the heating rate of 2-3 ℃/min, and preserving the heat for 3-4h at the 1170 ℃.
Further, the cooling mode in the microwave dielectric ceramic obtained by cooling the sintered biscuit to room temperature is an on-line cooling mode.
Further, the forming pressure of the dry pressing forming in the step S4 is 80-120 MPa.
Preferably, the forming pressure for dry press forming in the S4 step is 120 MPa.
Further, the main chemistry of the adhesive is polyvinyl alcohol and polyethylene glycol, and the mass percentage of the polyvinyl alcohol and the polyethylene glycol is 1.2-1.5% and 0.3-0.6%.
Preferably, the main chemistry of the adhesive is polyvinyl alcohol and polyethylene glycol, and the mass percentage of the polyvinyl alcohol and the polyethylene glycol is 1.5% and 0.6%.
The embodiment also provides a microwave dielectric ceramic with high dielectric constant, which comprises the following main chemical components: CaCO3-Li2CO3-Sm2O3-TiO2-MgO-Nb2O5-Al2O3，
Wherein, CaCO3：Li2CO3：Sm2O3：TiO2：MgO：Nb2O5：Al2O3The molar mass ratio of (A) to (B) is 16: 9: 12: 63-x: x/3: x/3: y, x is 0.05 and y is 0.02.
Specifically, the microwave dielectric ceramic is prepared from CaCO3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3MgO and Nb are added according to a reasonable raw material ratio2O5To (Mg)1/3Nb2/3)4+Composite ion replacement of Ti4+Shrink CaCO3-Li2CO3-Sm2O3-TiO2In crystal structure of [ TiO ]]6The octahedron enables the temperature coefficient to approach zero so as to meet the practical requirement; through reasonable raw material preparationSpecific addition of Al2O3Can play a pinning effect in the ceramic sintering process, and avoids Li in the raw materials2CO3The liquid phase formed by melting at about 600 ℃ causes the pores in the biscuit to be sealed in the ceramic body by the crystal grains, the process difficulty of obtaining high-density ceramic is difficult, and the reaction sintering CaCO is improved3-Li2CO3-Sm2O3-TiO2Quality factor of microwave dielectric ceramic.
EXAMPLE III
The third embodiment provides a method for preparing a microwave dielectric ceramic with a high dielectric constant, as shown in fig. 1, which includes the following steps:
s1, mixing raw material CaCO3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3According to each case to CaCO3-Li2CO3-Sm2O3-TiO2-MgO-Nb2O5-Al2O3Weighing and proportioning the chemical components, putting the proportioned mixture into a ball mill, and ball-milling the particle size of the mixture to a preset particle size;
s2, drying and screening the mixture after ball milling;
s3, adding a binder into the mixture dried and screened in the S2 step for granulation;
and S4, performing dry pressing forming on the granulated material obtained in the step S3 to obtain a biscuit, and performing binder removal and sintering on the biscuit to obtain the microwave dielectric ceramic.
In particular CaCO in the mixture3：Li2CO3：Sm2O3：TiO2：MgO：Nb2O5：Al2O3The molar mass ratio of (A) to (B) is 16: 9: 12: 63-x: x/3: x/3: y, x is 0.03, and y is 0.008-0.014.
Specifically, the preset particle size is 1-1.5 um.
Specifically, the step S4 of preparing the microwave dielectric ceramic by de-gumming and sintering the biscuit includes:
placing the biscuit in a high-temperature furnace, and slowly heating to discharge the glue;
placing the biscuit subjected to binder removal in a high-temperature furnace for slow sintering;
and cooling the sintered biscuit to room temperature to obtain the microwave dielectric ceramic.
Further, the specific process of placing the biscuit in a high-temperature furnace for slowly heating up for removing the glue is as follows: the temperature is raised from 50 ℃ to 900 ℃ at a rate of 1-2 ℃/min.
Further, the specific process of slowly sintering the biscuit in a high temperature furnace after the binder removal comprises the following steps: heating from 800 deg.C to 1190 deg.C at a heating rate of 2-3 deg.C/min, and maintaining at 1190 deg.C for 3-4 h.
Further, the cooling mode in the microwave dielectric ceramic obtained by cooling the sintered biscuit to room temperature is an on-line cooling mode.
Further, the forming pressure of the dry pressing forming in the step S4 is 80-120 MPa.
Preferably, the forming pressure for dry pressing in the S4 step is 100 MPa.
Further, the main chemistry of the adhesive is polyvinyl alcohol and polyethylene glycol, and the mass percentage of the polyvinyl alcohol and the polyethylene glycol is 1.2-1.5% and 0.3-0.6%.
Preferably, the main chemistry of the adhesive is polyvinyl alcohol and polyethylene glycol, and the mass percentage of the polyvinyl alcohol and the polyethylene glycol is 1.3% and 0.5%.
The implementation also provides a microwave dielectric ceramic with high dielectric constant, which comprises the following main chemical components: CaCO3-Li2CO3-Sm2O3-TiO2-MgO-Nb2O5-Al2O3，
Wherein, CaCO3：Li2CO3：Sm2O3：TiO2：MgO：Nb2O5：Al2O3In a molar mass ratio of16: 9: 12: 63-x: x/3: x/3: y, x is 0.01-0.05, and y is 0.008-0.02.
Preferably, x is 0.03 and y is 0.014.
Specifically, the microwave dielectric ceramic is prepared from CaCO3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3MgO and Nb are added according to a reasonable raw material ratio2O5To (Mg)1/3Nb2/3)4+Composite ion replacement of Ti4+Shrink CaCO3-Li2CO3-Sm2O3-TiO2In crystal structure of [ TiO ]]6The octahedron enables the temperature coefficient to approach zero so as to meet the practical requirement; al is added by reasonable raw material proportion2O3Can play a pinning effect in the ceramic sintering process, and avoids Li in the raw materials2CO3The liquid phase formed by melting at about 600 ℃ causes the pores in the biscuit to be sealed in the ceramic body by the crystal grains, the process difficulty of obtaining high-density ceramic is difficult, and the reaction sintering CaCO is improved3-Li2CO3-Sm2O3-TiO2Quality factor of microwave dielectric ceramic.
The microwave dielectric ceramic with high dielectric constant is obtained by adjusting the preparation process and the component ratio of the microwave dielectric ceramic, and is applied to the miniaturization of microwave components such as GPS antennas, dielectric resonators and the like.
Through tests, the properties of the microwave dielectric ceramic with high dielectric constant obtained in the first embodiment to the third embodiment are as follows:
examples Dielectric constant Quality factor Temperature coefficient of resonance frequency (ppm/. degree. C.) Density (g/cm)3)
A 102 5620 -5.0 4.83
II 92 5980 7.0 4.58
III 98 5760 3.3 4.67
According to the data in the table, analysis is carried out, after the mixture of the raw materials is ball-milled to a certain size, the microwave dielectric ceramic is prepared by direct molding, glue discharging and sintering, the preparation of precursor powder and a secondary grinding process are omitted, the prepared microwave dielectric ceramic has high dielectric constant, the micro application of microwave components such as a GPS antenna, a dielectric resonator and the like is met, the production cost is greatly reduced, powder pollution in a multiple grinding process is avoided, and the quality factor of the dielectric ceramic is effectively improved; meanwhile, by adjusting the values of x and y, the dielectric constant of the microwave dielectric ceramic can be adjusted between 92 and 102, the design requirements of different devices are met, and a higher quality factor and a near-zero temperature coefficient are obtained.
The foregoing description has disclosed fully preferred embodiments of the present invention. It should be noted that those skilled in the art can make modifications to the embodiments of the present invention without departing from the scope of the appended claims. Accordingly, the scope of the appended claims is not to be limited to the specific embodiments described above.

Claims (9)

1. A preparation method of microwave dielectric ceramic with high dielectric constant is characterized by comprising the following steps:
s1, mixing raw material CaCO3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3According to each case to CaCO3-Li2CO3-Sm2O3-TiO2-MgO-Nb2O5-Al2O3Weighing and proportioning the chemical components, putting the proportioned mixture into a ball mill, and ball-milling the particle size of the mixture to a preset particle size;
s2, drying and screening the mixture after ball milling;
s3, adding a binder into the mixture dried and screened in the S2 step for granulation;
and S4, performing dry pressing forming on the granulated material obtained in the step S3 to obtain a biscuit, and performing binder removal and sintering on the biscuit to obtain the microwave dielectric ceramic.
2. The method as claimed in claim 1, wherein CaCO is added to the mixture3、Li2CO3、Sm2O3、TiO2、MgO、Nb2O5And Al2O3The molar mass ratio of (A) to (B) is 16: 9: 12: 63-x: x/3: x/3: y, x is 0.01-0.05, and y is 0.008-0.02.
3. The method for preparing a microwave dielectric ceramic with a high dielectric constant as claimed in claim 1, wherein the predetermined particle size is 1-1.5 um.
4. The method of claim 1, wherein the step of discharging the biscuit and sintering to obtain the microwave dielectric ceramic in the step of S4 comprises:
placing the biscuit in a high-temperature furnace, and slowly heating to discharge the glue;
placing the biscuit subjected to binder removal in a high-temperature furnace for slow sintering;
and cooling the sintered biscuit to room temperature to obtain the microwave dielectric ceramic.
5. The method for preparing microwave dielectric ceramic with high dielectric constant according to claim 4, wherein the specific process of placing the biscuit in a high temperature furnace for slowly raising temperature to carry out binder removal is as follows: the temperature is raised from 50 ℃ to 900 ℃ at a rate of 1-2 ℃/min.
6. The method for preparing microwave dielectric ceramic with high dielectric constant according to claim 4, wherein the specific process of placing the biscuit in a high temperature furnace for slow sintering after binder removal is as follows: raising the temperature from 800 ℃ to 1170-1210 ℃ at the temperature raising rate of 2-3 ℃/min, and preserving the temperature for 3-4h at 1170-1210 ℃.
7. The method as claimed in claim 1, wherein the forming pressure of the dry press forming in the step S4 is 80 to 120 MPa.
8. The method for preparing microwave dielectric ceramic with high dielectric constant according to claim 1, wherein the main chemistry of the binder is polyvinyl alcohol and polyethylene glycol, and the mass percentage of the polyvinyl alcohol and the polyethylene glycol is 1.2-1.5% and 0.3-0.6%.
9. A microwave dielectric ceramic having a high dielectric constant, which is prepared by the method according to any one of claims 1 to 8.
CN201911076671.5A 2019-11-06 2019-11-06 Microwave dielectric ceramic with high dielectric constant and preparation method thereof Pending CN110723968A (en)

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