CN100392157C - Poly-seed crystal preparation method for YBaCuO single domain superconductor - Google Patents
Poly-seed crystal preparation method for YBaCuO single domain superconductor Download PDFInfo
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- CN100392157C CN100392157C CNB2005100593296A CN200510059329A CN100392157C CN 100392157 C CN100392157 C CN 100392157C CN B2005100593296 A CNB2005100593296 A CN B2005100593296A CN 200510059329 A CN200510059329 A CN 200510059329A CN 100392157 C CN100392157 C CN 100392157C
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Abstract
The present invention relates to a method for preparing a plurality of seed crystals of yttrium barium copper oxygen single domain superconducting blocks. The method comprises the procedures: 1. preforming blocks are prepared by the powder of 1.8 of Y, 2.4 of Ba, 3.4 of Cu and y of O; 2. SmBaCuO blocks in a single domain structure with the orientation of a c axis grow by a method of melting texture and top seed crystals, SmBaCuO seed crystals are obtained by directionally cutting, an an axis and a b axis of each of the seed crystals follow two sides of a square sheet, and the c axis follows the thickness direction of the sheet; 3. a plurality of SmBaCuO seed crystals are placed on the top surfaces of the preforming blocks equidistantly on the face formed by the an axis and the b axis, the SmBaCuO seed crystals are placed in a heating furnace, temperature is rapidly raised to 1040 DEG C to 1045 DEG C and is rapidly lowered to 1012 DEG C to 1017 DEG C after heat preservation for 1 to 2h, temperature screws is lowered to 975 to 985 DEG C at the speed rate of 0.1 to 1 DEG C per hour, the heating furnace is cooled to room temperature, and yttrium barium copper oxygen single domain superconducting blocks are prepared. The powder of 1.8 of Y<1-x>Gd<x>, 2.4 of Ba, 3.4 of Cu and y of O can be used for preparing a transition layer. The method of the present invention can produce YBaCuO single domain superconducting blocks with large size in shorter time.
Description
Technical field
The present invention relates to a kind of seediness crystal preparation method of yttrium barium copper oxide single domain superconduction piece.
Background technology
Top seed crystal technology and combining of melting texture growing technology are proved to be to prepare the successful methods of class monocrystalline (single domain) superconductor of single crystalline orientation.In the seed crystal technology of top, a seed crystal is placed on the top surface center of premolding YBaCuO piece, as unique nucleation centre, induces the YBaCuO piece to press the crystalline orientation directional solidification growth of seed crystal, forms single c-axle oriented superconduction piece.This superconduction piece also is known as single domain superconduction piece.Because the YBaCuO crystalline speed of growth very slow (the single domain superconduction piece of growth 3cm diameter needs about 100 hours usually, then needs hundreds of hours time greater than the single domain superconduction piece of 5cm diameter) is restricted the fast preparation of large size single domain superconduction.Simultaneously, any small disturbance all may cause the spontaneous nucleation growth of non-seed crystal in long directional freeze process, causes the superconduction piece to form multidomain structure.In addition, pyroprocessing also causes the inhomogeneous of superconduction piece performance for a long time.
Summary of the invention
The seediness crystal preparation method that the purpose of this invention is to provide a kind of single domain YBaCuO superconduction block can grow the YBaCuO single domain superconduction piece with large-size in the short period of time.
For achieving the above object, the present invention takes following technical scheme:
A kind of seediness crystal preparation method of yttrium barium copper oxide single domain superconduction piece, it is characterized in that: this method comprises the steps:
(1), adopts Y
1.8Ba
2.4Cu
3.4O
yPowdered preparation premolding piece;
(2), the one-domain structure SmBaCuO piece of the growth of the method by melting texture and top seed crystal c axle orientation, obtain the SmBaCuO seed crystal through the orientation cutting, make a, b axle of seed crystal two limits along square sheets, the c axle is along the thickness direction of thin slice;
(3), several SmBaCuO seed crystals are placed on it perpendicular to the mode of the top surface of premolding piece is equally spaced with the ab face, insert in the process furnace, be warming up to 1040 ℃～1045 ℃ with 300 ℃ speed per hour, be cooled to 1012 ℃～1017 ℃ with 200 ℃ speed per hour behind insulation 1～2h, be cooled to 970～985 ℃ with 0.1～1 ℃ speed per hour then, stove is chilled to room temperature subsequently, promptly makes yttrium barium copper oxide single domain superconduction piece.
In described step (1), at Y
1.8Ba
2.4Cu
3.4O
yPowder in be added with the Pt powder of 0.1-0.5wt%.
In described step (1), also adopt (Y
1-xGd
x)
1.8Ba
2.4Cu
3.4O
yThe premolding piece of powdered preparation multilayered structure, wherein, earlier with Y
1.8Ba
2.4Cu
3.4O
yPowder pack in the mould, again with (Y
1-xGd
x)
1.8Ba
2.4Cu
3.4O
yPowder pack in the mould, by the mode that single shaft is pressed, be pressed into the premolding piece of multilayered structure, orlop is Y
1.8Ba
2.4Cu
3.4O
yThe main stor(e)y that forms of powder, the upper strata is (Y
1-xGd
x)
1.8Ba
2.4Cu
3.4O
yThe transition layer that forms of powder, the scope of the x in formula is 0＜x≤1.
In described step (1), (Y
1-xGd
x)
1.8Ba
2.4Cu
3.4O
yPowder in be added with the Pt powder of 0.1-0.5wt%.
In described step (1), described transition layer is a multilayer, and transition layer reduces to arrange from top to bottom by the value of x gradually.Measure the peritectoid decomposition temperature T of YBaCuO by differential thermal analyzer
PBe 1010 ℃, the T of GdBaCuO
PBe 1041 ℃, the T of YGdBaCuO mixture
PRise with the increase of x is dull, by using the GdBaCuO and the YBaCuO powder of different ratios, obtain the continuous premolding piece that descends of peritectoid decomposition temperature from top to bottom, like this, utilize the mixture of YBaCuO and GdBaCuO in the premolding piece, to set up the method growth YBCO superconduction piece of component gradient, can improve the intergranular coupling in the brilliant sample of seediness.
In described step (3), the a axle of described each seed crystal and b direction of principal axis if random arrangement (Fig. 5 a), the crystallization shape of resulting sample is made up of a plurality of monodomain regions, crystal boundary place dephasign is assembled, cause non-superconducting to connect or the weak connection of superconduction, therefore, the preferably regular arrangement of a axle of each seed crystal and b direction of principal axis, regular arrangement can have following dual mode:
In described step (3), direction is consistent respectively with the b axle for a axle of described each seed crystal, and parallel or vertical with the line of centres of two contiguous seed crystals (Fig. 5 b).
In described step (3), direction is consistent respectively for a axle of described each seed crystal and b axle, and with the line of centres angle at 45 (Fig. 5 c) of two contiguous seed crystals.
Adopt above-mentioned two kinds of regular arrangement modes, the crystallization shape of resulting sample is a plurality of monodomain regions near the upper strata of seed crystal, and middle lower floor is coupled and forms a big monodomain region.
In described step (3), the quantity n of SmBaCuO seed crystal, n=1,2,3,4......, the corresponding single seed crystal of n=1, the corresponding seediness crystalline substance in n＞1.When the superconduction piece of the same size of preparation, n big more (the seed crystal spacing is more little), the time that growth single domain superconduction piece needs is short more.In described step (3), the SmBaCuO seed crystal is preferably n
2Individual, n=2-8.
Advantage of the present invention is:
The seediness crystal preparation method of this single domain YBaCuO superconduction block of the present invention is compared the time that can significantly shorten growth YBaCuO single domain superconduction piece with single seed crystal method.The principal feature of this method is:
1) directed cutting seed crystal makes a, b axle of seed crystal two limits along square sheets, and the c axle can make seed crystal regularly arranged along the thickness direction of thin slice like this.
2), make the crystalline orientation and the equal and opposite in direction of seed crystal induced growth at the top surface of the premolding superconduction piece seed crystal of evenly arranging at regular intervals.
3) premolding superconduction piece by the YBaCuO layer and the position thereon YBaCuO and the mixture transition layer of GdBaCuO constitute, the peritectoid decomposition temperature of each layer reduces from top to bottom; The method growth YBCO superconduction piece of component gradient is set up in utilization in the premolding piece, can improve the intergranular coupling in the brilliant sample of seediness.
4) according to the peritectoid decomposition temperature T of YBaCuO
PBe 1010 ℃, the T of GdBaCuO
PBe 1041 ℃, the T of YGdBaCuO mixture
PWith the dull rule that rises of the increase of x, the rational heat treatment system is set, make premolding piece order of crystallization from top to bottom.
5) thickness of transition layer and this layer crystal bulk-growth speeds match.
6) induce the bigger crystal of growth down to become the seed crystal of one deck down at seed crystal, this effect is successively transmitted, the crystal on upper strata links together during to the YBaCuO layer, forms a big seed crystal, thereby utilizes the brilliant method of seediness to grow the YBaCuO superconduction piece of one-domain structure.
Description of drawings
Fig. 1 is (Y
1-xGd
x)
1.8Ba
2.4Cu
3.4O
yThe peritectoid decomposition temperature of material
Fig. 2 is the synoptic diagram of cylindrical premolding piece
Fig. 3 is the synoptic diagram of preparation single domain SmBaCuO material
Fig. 4 is a single domain SmBaCuO material crystals orientation synoptic diagram
Fig. 5 is the 3 kind arrangement mode synoptic diagram of 4 seed crystals on the premolding piece, and wherein, Fig. 5 (a) is first kind of arrangement mode synoptic diagram; Fig. 5 (b) is second kind of arrangement mode synoptic diagram; Fig. 5 (c) is the third arrangement mode synoptic diagram.
Fig. 6 is the surface crystallization pattern synoptic diagram of the superconduction piece of seed crystal induced growth, and wherein, Fig. 6 (a) is single seed crystal pattern synoptic diagram; Fig. 6 (b) is random crystal boundary pattern synoptic diagram; Fig. 6 (c) is (100)/(100) or (010)/(010) crystal boundary pattern synoptic diagram; Fig. 6 (d) is (110)/(110) crystal boundary pattern synoptic diagram.Fig. 7 is the crystallization shape of single seed crystal method growth YBCO sample and captures Distribution of Magnetic Field figure that wherein, Fig. 7 (a) is that the surface crystallization pattern of sample shows figure; Fig. 7 (b) is for capturing the three-dimensional distribution map of field; Fig. 7 (c) captures the intensity of field isogram for concentric circles.
Fig. 8 be do not have transition layer 4 seed crystal YBCO samples crystallization shape and capture Distribution of Magnetic Field figure, wherein, Fig. 8 (a) be that the surface crystallization pattern of sample show to be schemed; Fig. 8 (b) is for capturing the three-dimensional distribution map of field; Fig. 8 (c) is for capturing the corresponding figure with three-dimensional distribution map of intensity of field isogram.
Fig. 9 is for the sample surfaces crystallization shape of embodiment 3 and capture field pattern, and wherein, Fig. 9 a is the surface crystallization pattern of sample, and Fig. 9 b is a three-dimensional distribution map of capturing, and Fig. 9 c is for capturing the intensity of field isogram.
Embodiment
The preparation method of pioneer's powder used in the present invention is as follows:
Pioneer's powder used in the present invention relates to Y
1.8Ba
2.4Cu
3.4O
y(YBaCuO), Gd
1.8Ba
2.4Cu
3.4O
y(GdBaCuO) and both mixture (Y
1-xGd
x)
1.8Ba
2.4Cu
3.4O
y(YGdBaCuO).Wherein, YBaCuO and GdBaCuO powder are with Y
2O
3Or Gd
2O
3With BaCO
3, CuO presses Y or Gd: Ba: Cu=1.8: 2.4: 3.4 molar ratio weighing, uniform mixing and roasting form respectively and contain YBa
2Cu
3O
Y(Y-123) phase and Y
2BaCuO
x(Y-211) YBaCuO pioneer's powder of phase, or contain GdBa
2Cu
3O
Y(Gd-123) phase and Gd
2BaCuO
x(Gd-211) GdBaCuO pioneer's powder of phase.For the granularity of 211 phases in the refinement final product 123 phase matrixes, all the ratio in 0.1～0.5wt% adds the Pt powder in YBaCuO and GdBaCuO powder.Above-mentioned YBaCuO and GdBaCuO powder mixed by a certain percentage obtain YGdBaCuO pioneer's powder.
Measure different ratios YGdBaCuO mixtures of material with differential thermal analyzer, the results are shown in Fig. 1.As seen from Figure 1, the peritectoid decomposition temperature T of YBaCuO
PBe 1010 ℃, the T of GdBaCuO
PBe 1041 ℃, the T of YGdBaCuO mixture
PRise with the increase of x is dull.Utilize this result, can obtain the powder mix of required peritectoid decomposition temperature by the ratio that changes YBaCuO and GdBaCuO.
The preparation method of premolding piece used in the present invention is as follows:
Be equipped with in the single domain superconductor in single seed crystal legal system, the composition of premolding piece is single YBaCuO.In the brilliant method of seediness, the main component of premolding piece is YBaCuO, can also contain a certain amount of YGdBaCuO.In the preparation of premolding piece, the mould of earlier an amount of YBaCuO powder being packed into, the YGdBaCuO powder that will the select x again mould of packing into, the mode moulding of pressing by single shaft.Fig. 2 has provided the synoptic diagram of premolding piece in the brilliant method of seediness, except that principal constituent YBaCuO layer B, has increased the transition layer A of YGdBaCuO composition.By changing the alternative amount x of Gd to Y, can make and contain a transition layer A or a plurality of transition layer A1, A2 ... the premolding piece.
The preparation method of seed crystal used in the present invention is as follows:
With Sm
2O
3, BaCO
3With CuO be raw material, press Sm: Ba: Cu=1.8: 2.4: 3.4 molar ratio weighing, uniform mixing and roasting form and to contain SmBa
2Cu
3O
y(Sm-123) phase and Sm
2BaCuO
x(Sm-211) SBCO pioneer's powder of phase is made the premolding piece by the mode of single shaft mold pressing.With the MgO monocrystalline as seed crystal, the one-domain structure SmBaCuO piece of the technology growth c axle orientation by melting texture and top seed crystal.As shown in Figure 3, MgO monocrystalline 1 is placed on the top surface center that the premolding piece is a SmBaCuO piece 2 as seed crystal, the c axle of seed crystal is parallel to the axle of premolding piece.The premolding piece that will have seed crystal is put into the process furnace of precise temperature control, be warming up to 1080～1090 ℃, be incubated after 0.5～1 hour fast cooling to 1060 ℃, slowly be cooled to 1020～1030 ℃ with 0.5～1.5 ℃ speed per hour then, stove is chilled to room temperature subsequently, obtains the bulk material of crystalline orientation as shown in Figure 4.Utilize similar method also can prepare the NdBaCuO bulk material of one-domain structure.
With diamond cutter directed cutting SmBaCuO or NdBaCuO single domain superconduction piece, the ab crystal face along single domain superconduction piece is cut into the thick thin slice of 1～2mm earlier, thin slice is cut into the square of about 2mm * 2mm, as seed crystal again.The c axle that makes seed crystal is along thickness direction, and a axle and b axle are along foursquare limit.
The arrangement mode of seed crystal of the present invention on the premolding piece is as follows:
Usually use n
2(n=1,2 ...) on the equally spaced top surface that is placed on the premolding piece of individual seed crystal, keep the c direction of principal axis of seed crystal parallel with the axis of cylindric premolding piece.Fig. 5 has provided when using 4 seed crystals, the 3 kind different arrangement modes of seed crystal on the premolding piece.Shown in Fig. 5 (a) is first kind of arrangement mode, and a axle (or b axle) of seed crystal is random among Fig. 5 (a); Shown in Fig. 5 (b) is second kind of arrangement mode, a axle of 4 seed crystals (or b axle) direction unanimity among Fig. 5 (b), and parallel or vertical with the nearest neighbour seed crystal line of centres; Shown in Fig. 5 (c) is the third arrangement mode, a axle of 4 seed crystals (or b axle) direction unanimity among Fig. 5 (c), but with nearest neighbour seed crystal line of centres angle at 45.
Growth and crystallization shape to the made superconduction piece in the method for the present invention are described as follows:
The premolding piece of placing seed crystal is as shown in Figure 5 put into process furnace, by common melting texture growing art breading.Promptly be rapidly heated to 1040 ℃～1045 ℃, be incubated after 1～2 hour fast cooling to 1012 ℃～1017 ℃, slowly be cooled to 970～985 ℃ with 0.1～1 ℃ speed approximately per hour then, stove is chilled to room temperature subsequently.
The superconduction piece that adopts above-mentioned prepared to go out has surface crystallization pattern shown in Figure 6.Fig. 6 (a) is to use the sample of single seed crystal induced growth, and it is that the center is to extraradial four fan sections that its top surface presents with the seed crystal.The X-ray diffraction result confirms that each sector all is c axle orientation, and is parallel with the symmetry axis of cylindrical sample, and has only very little differential seat angle between the c axle of adjacent sectors.Superconduction piece with this surface growth style has whole C axle orientation, and superconduction circulation can flow in superconduction piece entire scope.This coupling all-in-one-piece superconducting material is called as " single domain " superconducting material.Fig. 6 (b), 6 (c), 6 (d) are to use the sample of four seeded growths, respectively corresponding above-mentioned first, second and third kind arrangement mode of their arrangement mode.Identical with single seed crystal method, all be the single domain of c axle orientation in each seed crystal inductive zone, but adjacent seed crystal induce the interface orientation that forms between the district different.Fig. 6 (b) (corresponding above-mentioned first kind of arrangement mode) does not consider seed crystal a axle and the axial consistence of b, forms random crystal boundary between each seed crystal inductive monodomain region.The a axle and the b direction of principal axis of each seed crystal are parallel to each other among Fig. 6 (c) (the above-mentioned second kind of arrangement mode of correspondence) and 6 (d) (corresponding above-mentioned the third arrangement mode), form (100)/(100) (or (010)/(010)) crystal boundary and (110)/(110) crystal boundary (thick deceiving shown in the interlacing line among the figure) respectively.
X-ray diffraction is the result show: when 1) the premolding piece was single YBCO composition, the sample with Fig. 6 (b) crystallization shape was made up of four monodomain regions, and crystal boundary place dephasign is assembled, and caused non-superconducting to connect or superconduction is weak connects; Upper strata with close seed crystal of sample of Fig. 6 (c) and 6 (d) is four monodomain regions, and middle lower floor is coupled and forms a big monodomain region.2) the premolding piece is when having the multilayered structure of transition layer, sample with Fig. 6 (b) crystallization shape still is made up of four monodomain regions, and under the condition of suitable transition layer composition and thickness, the sample with Fig. 6 (c) and 6 (d) can be coupled into one does not have the weak big monodomain region that is connected of crystal boundary.
Be coupled into the sample of the brilliant method growth of seediness of a big single domain, it is captured flux distribution and demonstrates and same unimodal of the single domain sample of single seed crystal method growth, captures the intensity of field height.The be coupled flux distribution of capturing of sample (upper strata is a multidomain, and middle lower floor is a single domain) of part is a multimodal, and the corresponding seed crystal in each peak is induced the district, captures intensity of field and is lower than complete coupled single domain sample.
Verified, utilize the mixture of YBaCuO and GdBaCuO in the premolding piece, to set up the method growth YBCO superconduction piece of component gradient, can improve the intergranular coupling in the brilliant sample of seediness.By using the GdBaCuO and the YBaCuO powder of different ratios, obtain the continuous premolding piece that descends of peritectoid decomposition temperature from top to bottom, in conjunction with the brilliant a of control seediness, b axle relative orientation, and the coupling of distance and the transition region thickness and the Y-123 crystal grain ab crystal face speed of growth between the seed crystal, the orientation crystal grain that makes the superiors' seed crystal induce nucleation to grow up becomes the big area seed crystal of one deck down, by the transmission between the adjacent layers, obtain the single domain material that does not have non-superconducting to connect.This method has broken through can't the grow obstacle of bigger single domain sample of single seed crystal, can grow the single domain superconducting material in the short period of time.
Comparative example 1:
Composition is Y
1.8Ba
2.4Cu
3.4O
yPowder 80 gram, the Pt powder that adds 0.2 weight percent, be pressed into the piece of diameter 35mm after mixing, the SmBaCuO seed crystal of a 2mm * 2mm * 1mm is placed on the top surface center of premolding piece, go into process furnace, be rapidly heated to 1040 ℃, be incubated after 1 hour with 200 ℃ speed fast cooling to 1015 ℃ per hour with 300 ℃ speed per hour, slowly be cooled to 980 ℃ with 0.3 ℃ speed per hour then, stove is chilled to room temperature subsequently.The needed time of directional freeze is approximately 120 hours.The surface crystallization pattern of sample is shown in Fig. 7 a, and is identical with the one-domain structure synoptic diagram of Fig. 6 a.Capture magnetic-field measurement after 475 ℃ of oxygen atmospheres are handled 100 hours down, the three-dimensional distribution map of capturing the field is taper unimodal (seeing Fig. 7 b), and capturing the intensity of field isogram is concentric(al) circles (seeing Fig. 7 c).
Comparative example 2:
Composition is Y
1.8Ba
2.4Cu
3.4O
yPowder 145 gram, the Pt powder that adds 0.2 weight percent, be pressed into the piece of diameter 46mm after mixing, the SmBaCuO seed crystal of a 2mm * 2mm * 1mm is placed on the top surface center of premolding piece, go into process furnace, be rapidly heated to 1040 ℃ with 300 ℃ speed per hour, be incubated after 2 hours with 200 ℃ speed fast cooling to 1017 ℃ per hour, slowly be cooled to 1012 ℃ with 0.5 ℃ speed per hour then, be cooled to 980 ℃ with 0.25 ℃ speed per hour from 1012 ℃, slowly be cooled to 975 ℃ with 0.5 ℃ speed per hour again, stove is chilled to room temperature subsequently.The needed time of directional freeze is approximately 150 hours.The surface crystallization pattern of sample and a three-dimensional distribution map of capturing and isogram and comparative example 1 are similar.
Embodiment 1:
Composition is Y
1.8Ba
2.4Cu
3.4O
yPowder 145 gram, the Pt powder that adds 0.2 weight percent, be pressed into the piece of diameter 46mm after mixing, the SmBaCuO seed crystal of 4 2mm * 2mm * 1mm is with the top surface that equidistantly is placed on the premolding piece of about 20mm, go into process furnace, be rapidly heated to 1042 ℃, be incubated after 1.5 hours with 200 ℃ speed fast cooling to 1015 ℃ per hour with 300 ℃ speed per hour, slowly be cooled to 980 ℃ with 0.4 ℃ speed per hour then, stove is chilled to room temperature subsequently.The needed time of directional freeze is approximately 88 hours, is starkly lower than the comparable size superconduction piece used time of directional freeze (150 hours) in the comparative example 2.The surface crystallization pattern of sample is shown in Fig. 8 a, and is identical with the crystallization synoptic diagram of Fig. 6 c.After handling 100 hours down, 475 ℃ of oxygen atmospheres capture magnetic-field measurement, the three-dimensional distribution map top of capturing the field demonstrates 4 peaks, the corresponding seed crystal of each peak position, the middle and lower part is coupled into one (seeing Fig. 8 b), captures intensity of field isogram corresponding with three-dimensional distribution map (seeing Fig. 8 c).
Embodiment 2:
Composition is Y
1.8Ba
2.4Cu
3.4O
yPowder 80 gram, the Pt powder that adds 0.2 weight percent, be pressed into the piece of diameter 35mm after mixing, the SmBaCuO seed crystal of 4 2mm * 2mm * 1mm is with the top surface that equidistantly is placed on the premolding piece (a direction of principal axis unanimity that keeps each seed crystal of 14mm, and it is parallel with the line of centres of two contiguous seed crystals), go into process furnace, be rapidly heated to 1042 ℃ with 300 ℃ speed per hour, be incubated after 1 hour with 200 ℃ speed fast cooling to 1015 ℃ per hour, slowly be cooled to 985 ℃ with 0.4 ℃ speed per hour then, stove is chilled to room temperature subsequently.The needed time of directional freeze is approximately 75 hours, is starkly lower than the comparable size superconduction piece used time of directional freeze (120 hours) in the comparative example 1.The surface crystallization pattern of sample is with to capture the intensity of field isogram mutually similar to Example 1 with three-dimensional distribution map.
Embodiment 3:
Composition is Y
1.8Ba
2.4Cu
3.4O
yPowder 80 gram, the Pt powder that adds 0.2 weight percent mixes, and places pressing mold.Y
1.8Ba
2.4Cu
3.4O
y: Gd
1.8Ba
2.4Cu
3.4O
y=0.8: 0.2 YBaCuO and GdBaCuO powder mix 7 grams, the Pt powder that adds 0.2 weight percent, pour in the pressing mold after mixing, place the top of YBaCuO powder, be pressed into the piece of diameter 35mm, the SmBaCuO seed crystal of 4 2mm * 2mm * 1mm sizes is the top surface that is placed on the premolding piece (a direction of principal axis unanimity that keeps each seed crystal of (14mm) equidistantly, and it is parallel with the line of centres of two contiguous seed crystals), go into process furnace, be rapidly heated to 1042 ℃ with 300 ℃ speed per hour, be incubated after 1 hour with 200 ℃ speed fast cooling to 1015 ℃ per hour, slowly be cooled to 985 ℃ with 0.4 ℃ speed per hour then, stove is chilled to room temperature subsequently.The needed time of directional freeze is approximately 75 hours.The surface crystallization pattern of sample is shown in Fig. 9 a, and is identical with the crystallization synoptic diagram of Fig. 6 c.Capture magnetic-field measurement after 475 ℃ of oxygen atmospheres are handled 100 hours down, the three-dimensional distribution map of capturing the field is taper unimodal (seeing Fig. 9 b), captures the approximate concentric(al) circles (seeing Fig. 9 c) of intensity of field isogram.
By above-mentioned several comparative examples and embodiment as can be seen, utilize the brilliant bonded method of composition transition layer and seediness can grow the single domain superconduction piece same, and can shorten the time of directional solidification growth significantly with single seed crystal method.The spacing of dwindling the seediness crystalline substance can further shorten solidifies growth time, and larger sized single domain superconduction piece is suitable for growing.
Method of the present invention also is applicable to the preparation of other RE, Ba and Cu oxides (REBaCuO) single domain superconducting material under the condition of selecting other transition layer compositions.
Claims (9)
1. the seediness crystal preparation method of a yttrium barium copper oxide single domain superconduction piece, it is characterized in that: this method comprises the steps:
(1), adopts Y
1.8Ba
2.4Cu
3.4O
yPowdered preparation premolding piece;
(2), the one-domain structure SmBaCuO piece of the growth of the method by melting texture and top seed crystal c axle orientation, and directed cutting promptly obtains the SmBaCuO seed crystal, makes a, b axle of seed crystal two limits along square sheets, the c axle is along the thickness direction of thin slice;
(3), the face that several SmBaCuO seed crystals are formed with a, b axle and equidistantly being placed on the top surface of premolding piece, insert in the process furnace, be warming up to 1040 ℃～1045 ℃ with 300 ℃ speed per hour, be cooled to 1012 ℃～1017 ℃ with 200 ℃ speed per hour behind insulation 1～2h, be cooled to 970～985 ℃ with 0.1～1 ℃ speed per hour then, stove is chilled to room temperature subsequently, promptly makes yttrium barium copper oxide single domain superconduction piece.
2. the seediness crystal preparation method of yttrium barium copper oxide single domain superconduction piece according to claim 1 is characterized in that: in described step (1), at Y
1.8Ba
2.4Cu
3.4O
yPowder in be added with the Pt powder of 0.1-0.5wt%.
3. the seediness crystal preparation method of yttrium barium copper oxide single domain superconduction piece according to claim 2 is characterized in that: in described step (1), also adopt (Y
1-xGd
x)
1.8Ba
2.4Cu
3.4O
yThe premolding piece of powdered preparation multilayered structure, wherein, earlier with Y
1.8Ba
2.4Cu
3.4O
yPowder pack in the mould, again with (Y
1-xGd
x)
1.8Ba
2.4Cu
3.4O
yPowder pack in the mould, by the mode that single shaft is pressed, be pressed into the premolding piece of multilayered structure, orlop is Y
1.8Ba
2.4Cu
3.4O
yThe main stor(e)y that forms of powder, the upper strata is (Y
1-xGd
x)
1.8Ba
2.4Cu
3.4O
yThe transition layer that forms of powder, the scope of the x in formula is 0＜x≤1.
4. the seediness crystal preparation method of yttrium barium copper oxide single domain superconduction piece according to claim 3 is characterized in that: in described step (1), and (Y
1-xGd
x)
1.8Ba
2.4Cu
3.4O
yPowder in be added with the Pt powder of 0.1-0.5wt%.
5. the seediness crystal preparation method of yttrium barium copper oxide single domain superconduction piece according to claim 4 is characterized in that: in described step (1), described transition layer is a multilayer, and transition layer reduces arrangement from top to bottom gradually by the value of x.
6. according to the seediness crystal preparation method of claim 4 or 5 described yttrium barium copper oxide single domain superconduction pieces, it is characterized in that: in described step (3), the a axle of described each seed crystal or b direction of principal axis unanimity, and parallel or vertical with the line of centres of two contiguous seed crystals.
7. according to the seediness crystal preparation method of claim 4 or 5 described yttrium barium copper oxide single domain superconduction pieces, it is characterized in that: in described step (3), a axle of described each seed crystal or b direction of principal axis unanimity, and with the line of centres angle at 45 of two contiguous seed crystals.
8. the seediness crystal preparation method of yttrium barium copper oxide single domain superconduction piece according to claim 6 is characterized in that: in described step (3), the SmBaCuO seed crystal is n
2Individual, n=2-8.
9. the seediness crystal preparation method of yttrium barium copper oxide single domain superconduction piece according to claim 7 is characterized in that: in described step (3), the SmBaCuO seed crystal is n
2Individual, n=2-8.
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| CN101471162B (en) * | 2007-12-28 | 2011-01-19 | 北京有色金属研究总院 | Method for improving GdBaCuO high-temperature superconductor performance by Gd211 produced by doping low temperature combustion synthesis method |
| CN101265099B (en) * | 2008-04-11 | 2012-03-14 | 中国科学技术大学 | Preparation method of high-temperature superconducting material |
| CN101319380B (en) * | 2008-05-15 | 2011-04-20 | 上海交通大学 | Method for rare earth 242 phase control component for growing superconducting block material |
| CN101545139B (en) * | 2009-03-26 | 2011-06-15 | 上海交通大学 | Method for preparing yttrium barium copper oxygen superconducting block material by taking Ba3Cu5*Ox powder as fluid |
| CN101665980B (en) * | 2009-09-25 | 2012-01-11 | 陕西师范大学 | Infiltration method for preparing single-domain Gd-Ba-Cu-O superconducting block |
| CN101665981B (en) * | 2009-09-25 | 2012-01-11 | 陕西师范大学 | Preparation method of single-domain Gd-Ba-Cu-O superconducting block |
| CN103198900B (en) * | 2012-01-05 | 2016-05-18 | 李忠让 | A kind of preparation method of conductor material |
| CN102747416B (en) * | 2012-07-13 | 2015-01-21 | 上海交通大学 | Method of oriented induced growth of REBCO superconductive block from multiple seed crystals in asymmetric(110)/(110) manner |
| CN105401217B (en) * | 2015-12-25 | 2019-01-11 | 上海交通大学 | Utilize the method for sheet REBCO crystal growth REBCO bulk |
| CN107059127B (en) * | 2017-03-17 | 2019-04-16 | 陕西师范大学 | A kind of method of bottom seed crystal infiltration growth method preparation single domain rare earth barium copper oxide superconducting ring |
| CN107287658B (en) * | 2017-04-28 | 2019-08-16 | 陕西师范大学 | A kind of method that pure-oxide pre-sintering method prepares single domain yttrium barium copper oxide superconductor |
| CN109943890B (en) * | 2019-03-21 | 2021-02-12 | 上海交通大学 | Method for growing REBCO high-temperature superconducting crystal by using precursor component |
| CN113430646B (en) * | 2021-06-25 | 2022-05-13 | 上海交通大学 | Method for inducing growth of REBCO superconducting block by using single seed crystal bridge structure |
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