Method for inducing growth of REBCO superconducting block by using single seed crystal bridge structure
阅读说明：本技术 利用单籽晶桥式结构诱导生长rebco超导块材的方法 (Method for inducing growth of REBCO superconducting block by using single seed crystal bridge structure ) 是由 姚忻 朱彦涵 于 2021-06-25 设计创作，主要内容包括：本发明提供一种利用单籽晶桥式结构诱导生长REBCO超导块材的方法,包括以下步骤：配制RE123和RE211纯相粉末,按照RE123+30mol％RE211+1wt％CeO2的组分配料,充分碾磨混合均匀,得到前驱粉料；根据模具直径不同,将所述粉料称取合适质量,放入模具,压制成圆柱形状的籽晶桥1个、缓冲层2～3个和前驱体1个；将籽晶、籽晶桥、缓冲层、前驱体从上至下依次放置；所述籽晶、所述籽晶桥、所述缓冲层构成单籽晶桥式结构；其中,所述籽晶放置在所述籽晶桥的上表面中心,所述籽晶桥搭设在所述缓冲层上方,所述缓冲层沿所述籽晶[110]晶向排列成一列；将所述放置好的前驱体连同和所述单籽晶桥式结构置于生长炉中进行顶部籽晶熔融织构生长,以实现(110)∥(110)取向诱导生长REBCO超导块材。(The invention provides a method for inducing growth of REBCO superconducting block materials by utilizing a single-seed crystal bridge structure, which comprises the following steps: preparing RE123 and RE211 pure-phase powder, mixing the materials according to the components of RE123+30 mol% of RE211+1 wt% of CeO2, fully grinding and uniformly mixing to obtain precursor powder; according to different diameters of the dies, the powder is weighed to a proper mass and placed in the dies to be pressed into 1 seed crystal bridge, 2-3 buffer layers and 1 precursor in a cylindrical shape; placing seed crystals, seed crystal bridges, buffer layers and precursors in sequence from top to bottom; the seed crystal, the seed crystal bridge and the buffer layer form a single seed crystal bridge structure; wherein the seed crystal is placed in the center of the upper surface of the seed crystal bridge, the seed crystal bridge is erected above the buffer layer, and the buffer layer is arranged in a line along the crystal direction of the seed crystal [110 ]; and (3) placing the placed precursor and the single-seed crystal bridge structure in a growth furnace to perform top-seed melt texture growth so as to realize (110)// (110) orientation-induced growth of the REBCO superconducting bulk material.)
1. A method for inducing growth of REBCO superconducting bulk material by using a single seed crystal bridge structure is characterized by comprising the following steps:
step one, RE is added according to the proportion of RE, Ba, Cu and 2:3 and RE, Ba, Cu and 2:1:12O3，BaCO3And CuO powder to prepare the original powder of RE123 and RE 211;
fully and uniformly mixing the original powder, and sintering for 48 hours at 900 ℃ in an air environment; grinding and sintering the sintered powder again, and repeating the same process for three times;
step three, the RE123 powder and the RE211 powder obtained in the step two are mixed according to RE123+30 mol% RE211+1 wt% CeO2The components are mixed, fully milled and uniformly mixed to obtain precursor powder;
step four, weighing the powder with proper mass according to different diameters of the mold, putting the powder into the mold, and pressing the powder into 1 seed crystal bridge, 2-3 buffer layers and 1 precursor in a cylindrical shape;
placing the seed crystal, the seed crystal bridge, the buffer layer and the precursor in sequence from top to bottom; the seed crystal, the seed crystal bridge and the buffer layer form a single seed crystal bridge structure; wherein the seed crystal is placed in the center of the upper surface of the seed crystal bridge, the seed crystal bridge is erected above the buffer layer, and the buffer layer is arranged in a line along the crystal direction of the seed crystal [110 ];
and sixthly, placing the precursor and the single-seed crystal bridge structure in a growth furnace to perform top-seed crystal melt texture growth so as to realize (110)/110 oriented induced growth of the REBCO superconducting bulk material.
2. The method of claim 1, wherein: the top seed crystal melt texture growth process comprises the following steps:
raising the temperature in the growth furnace to a first temperature within a first time, and preserving the heat for 1-3 hours;
raising the temperature in the growth furnace to a second temperature within a second time, and preserving the heat for 1-3 hours;
reducing the temperature in the growth furnace to a third temperature for a third time;
reducing the temperature in the growth furnace to a fourth temperature for a fourth time;
and finally, quenching to obtain the REBCO superconducting block.
3. The method of claim 2, wherein: the first time is 3-5 hours, and the first temperature is 850-950 ℃; the second time is 1-2 hours, and the second temperature is 40-80 ℃ higher than the peritectic reaction temperature of the REBCO superconducting material; the third time is 0.5-1 hour, and the third temperature is the peritectic reaction temperature of the REBCO material; the fourth time is 10-80 hours, and the fourth temperature is 5-40 ℃ lower than the peritectic reaction temperature.
4. The method of claim 1, wherein: the seed crystal is in c-axis orientation, and the seed crystal is an NdBCO/MgO or NdBCO/YBCO/MgO film seed crystal.
5. The method of claim 1, wherein: the size of the seed crystal is 2mm multiplied by 2 mm.
6. The method of claim 1, wherein: in the fourth step, the diameter of the seed crystal bridge is 10mm, and 0.6g of seed crystal bridge is weighed and pressed; the diameter of the buffer layer is 5mm, and 0.15-0.2 g of buffer layer is weighed and pressed; the diameter of the precursor is more than or equal to 30 mm.
7. The method of claim 1, wherein: and RE is Y, Gd, Sm or Nd.
Technical Field
The invention belongs to the technical field of superconducting material growth methods, and particularly relates to a method for realizing (110)// (110) oriented induced growth of an REBCO superconducting bulk material by using a film seed crystal and combining a bridge structure.
Background
self-REBa2Cu3O7-δ(REBCO, RE123, rare earth barium copper oxygen, wherein RE is selected from Y, Gd, Sm, Nd and the like) high-temperature superconductors have been discovered since the superconductors have the advantages of complete diamagnetism and high critical electricityThe huge commercial potential brought by the properties of the current density, the high freezing magnetic field and the like, such as flywheel energy storage, permanent magnets, magnetic levitation force elements and the like, arouses wide attention of people. As a necessary premise for application, the preparation of REBCO bulk materials having large size and high performance is a problem that must be solved. So far, a Top-Seeded Melt Textured Growth (TSMTG) is generally considered to be a potential REBCO high-temperature superconducting bulk preparation method. In the growth process, a single seed crystal is placed in the center of the upper surface of the REBCO precursor and used as a unique nucleation point to induce the REBCO block to directionally solidify and grow according to the seed crystal orientation, and finally, a single-domain superconducting block with single c-axis orientation is formed. However, due to the lower growth rate of RE123, it takes a long time to obtain a large-sized superconducting bulk; and the excessive growth time can cause the problems of spontaneous nucleation, coarsening of the RE211 crystal grains in the high-temperature phase and the like. Therefore, it is important to shorten the preparation time for large-sized samples.
The melt texture method of multiple seed crystals is an effective method for solving the problem of overlong growth time of a superconducting block, namely, a plurality of seed crystals are placed on the upper surface of a sample according to a certain orientation. Because a plurality of seed crystals induce growth at the same time, the time required by the whole preparation process is greatly shortened. However, it has been found that, since the conventional multi-seed crystal method is generally placed at (100)/(100), a large amount of non-superconducting phase remains in the grain boundary of the sample, which prevents the superconducting current loop from passing through the grain boundary, and finally, a plurality of small superconducting current loops instead of a whole large superconducting current loop exist in the sample, and the overall performance is greatly reduced. Meanwhile, in the traditional preparation process of placing the induction blocks with multiple seed crystals at equal intervals, the weak connection of grain boundaries in the blocks can be further reduced along with the increase of the number of the seed crystals, so that the superconducting performance of the blocks is reduced.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for realizing (110/(110) orientation-induced growth of REBCO bulk superconductor by using a thin film seed crystal in combination with a bridge structure, for more economical and efficient popularization of REBCO bulk superconductor applications.
The invention provides a method for realizing (110)// 110 orientation induced growth of REBCO superconducting bulk material by a single seed crystal bridge structure, which comprises the following steps:
step one, RE is added according to the proportion of RE, Ba, Cu and 2:3 and RE, Ba, Cu and 2:1:12O3，BaCO3And CuO powder were formulated as raw powders of RE123 and RE 211.
And step two, fully and uniformly mixing the original powder, and sintering for 48 hours at 900 ℃ in an air environment. In order to ensure that the RE123 and RE211 phases with uniform and single components are finally obtained, the sintered powder is ground and sintered again, and the same process is repeated for three times.
Step three, the RE123 and RE211 pure phase powder obtained in the step two is mixed according to RE123+30 mol% RE211+1 wt% CeO2The components are mixed, fully milled and uniformly mixed to obtain precursor powder.
And step four, weighing the powder according to different diameters of the molds, putting the powder into the molds, and pressing the powder into 1 seed crystal bridge, 2-3 buffer layers and 1 precursor in a cylindrical shape.
Placing the seed crystal, the seed crystal bridge, the buffer layer and the precursor in sequence from top to bottom; the seed crystal, the seed crystal bridge and the buffer layer form a single seed crystal bridge structure; wherein the seed crystal is placed at the center of the upper surface of the seed crystal bridge, the seed crystal bridge is erected above the buffer layer, and the buffer layer is arranged in a row along the crystal direction of the seed crystal [110] (namely on the extension line of the crystal direction of the seed crystal [110 ]).
And sixthly, placing the precursor and the single-seed crystal bridge structure in a growth furnace to perform top seed crystal melt texture growth.
Further, the top seed crystal melt texture growth process comprises the following steps:
raising the temperature in the growth furnace to a first temperature within a first time, and preserving the heat for 1-3 hours;
raising the temperature in the growth furnace to a second temperature within a second time, and preserving the heat for 1-3 hours;
reducing the temperature in the growth furnace to a third temperature for a third time;
reducing the temperature in the growth furnace to a fourth temperature for a fourth time;
and finally, quenching to obtain the REBCO superconducting block.
Further, the first time is 3-5 hours, and the first temperature is 850-950 ℃; the second time is 1-2 hours, and the second temperature is 40-80 ℃ higher than the peritectic reaction temperature of the REBCO superconducting material; the third time is 0.5-1 hour, and the third temperature is the peritectic reaction temperature of the REBCO material; the fourth time is 10-80 hours, and the fourth temperature is 5-40 ℃ lower than the peritectic reaction temperature.
Optionally, the number of the buffer layers is 2-3, and the buffer layers are selected according to the size of the block material which needs to grow actually.
Preferably, the seed crystal is an NdBCO/YBCO/MgO film seed crystal.
Preferably, the size of the seed crystal is 2mm × 2 mm.
Furthermore, cerium oxide, platinum and the like can be doped in the precursor to inhibit melt loss.
Furthermore, the diameter of the seed crystal bridge is 10mm, and 0.6g of seed crystal bridge is generally weighed and pressed; the diameter of the buffer layer is 5mm, and 0.15-0.2 g of buffer layer is generally weighed and pressed; the diameter of the precursor is more than or equal to 30 mm.
Furthermore, RE in the REBCO superconducting material is Y, Gd, Sm or Nd.
The invention provides a method for realizing (110)// 110 oriented induced growth of REBCO superconducting bulk material by using a single-seed-crystal bridge structure, which has the following beneficial effects:
1. the invention adopts a (110)// 110 multi-seed crystal arrangement mode, effectively avoids the generation of (100)/(100) grain boundaries among different seed crystals, can effectively discharge residual melt at the grain boundaries, and is beneficial to improving the performance of REBCO block materials.
2. The invention realizes the effect of multi-seed crystal induction by combining the seed crystal bridge with the structure of the buffer layer, not only can effectively shorten the time for growing the block material, but also ensures the consistency of the orientation among a plurality of seed crystals (actually, all buffer layers). The method is simple, easy to operate and controllable in repetition.
3. The method can realize the aim only by one seed crystal, uses less materials, can effectively reduce the time cost and the economic cost of the preparation of the REBCO superconducting block, has positive effects on saving resources and improving the utilization rate of the resources, and has positive effects on protecting the ecological environment.
4. The invention is also applicable to the orientation induced growth of REBCO (such as GdBCO, SmBCO, NdBCO and the like) blocks with high crystallization reaction temperature due to the adoption of the film seed crystals with high thermal stability.
Drawings
The invention is further described below with reference to the accompanying drawings.
FIG. 1 illustrates the formation and growth process of (100)/(100) grain boundaries when conventional multi-seeds are placed at 0 °; the arrow indicates the direction of forward movement of the growth front.
FIG. 2 illustrates the formation and growth process of (110)/(110) grain boundaries when multiple seeds are placed at 45 °; the arrow indicates the direction of forward movement of the growth front.
FIG. 3 illustrates a GdBCO bulk sample grown using a four-seed 45-degree placement mode; the arrows indicate the growth lines of the grains on the left side of the photograph.
Fig. 4 is a schematic diagram illustrating seed positions and growth processes corresponding to two growth modes when a GdBCO bulk sample is grown using a four-seed 45 ° placement mode.
FIG. 5 shows a top view of a sample with a single seed bridge configuration to achieve (110)/110 orientation induction; (a) the variation of crystal growth with time using 2 buffer layers is shown by- (d).
Fig. 6 shows the growth of the crystal when 3 buffer layers are used for the single seed bridge structure.
FIG. 7 is a cross-sectional view of a sample showing the use of a single seed bridge configuration to achieve (110)/110 orientation induction using 2 buffer layers.
FIG. 8 is a cross-sectional view of a sample showing a single seed bridge configuration using 3 buffer layers to achieve (110)/110 orientation induction.
Fig. 9 illustrates the crystal induced growth for a single seed bridge configuration using 4 buffer layers (top view of the sample).
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification.
The invention concept of the invention is as follows:
in the conventional multi-seed melt texture method, the seed crystal is usually arranged in the orientation of (100)/(100) (hereinafter referred to as 0 ° arrangement). As the growth front advances, the high temperature phase and impurity phase in the bulk are correspondingly pushed out. Taking 2 seed crystals as an example, as shown in FIG. 1, since the (100) crystal plane contacts the grain boundary in the form of a whole plane when aligned at 0 °, the non-superconducting phase of the growth front is trapped near the grain boundary without being excluded. Such non-superconducting phase enriched grain boundaries are referred to as "contaminated" grain boundaries, which impede the passage of superconducting current loops, resulting in a substantial reduction in bulk properties.
In contrast, if a plurality of seed crystals are aligned in the (110)/110 orientation (hereinafter referred to as 45 ℃ alignment), no "contaminated" grain boundaries occur. Also taking 2 seed crystals as an example, as shown in fig. 2, since the (110) crystal plane contacts the grain boundary in the form of one point when aligned at 45 °, the non-superconducting phase of the growth front is not captured into the grain boundary at this time. Furthermore, these non-superconducting phases are also pushed towards the edges of the sample as growth continues, ensuring "cleanliness" throughout the sample. Therefore, the (110)/(110) grain boundary does not obstruct the passage of superconducting current loop, thereby improving the performance of the multi-seed crystal induced growth bulk. On the other hand, it is known that, for the REBCO system superconducting material, the (110) crystal plane is an unbalanced growth plane and thus a fast growth plane. When the multiple seed crystals are arranged at 45 degrees, the advantage of rapid growth is beneficial to further shortening the time for preparing the sample on the basis of simultaneous growth of the multiple seed crystals, is particularly suitable for large-size samples, and meets the requirement of industrialization.
The disadvantage is that, firstly, the 45 ° arrangement does not change the number of seeds used, and for the requirements of industrial applications, such a growth method is undoubtedly much more expensive than the single-seed method. Secondly, the placement of the seed crystals in 45 ° alignment is theoretically easy to achieve, but actually, due to manual operation or seed crystal drift in a high-temperature molten state, it is easy to cause that individual seed crystals and other seed crystals do not completely assume 45 ° alignment. The GdBCO block grown with four seeds as shown in fig. 3, the left two seeds did not fully achieve (110)/(110) when left, resulting in induced growth of grain boundaries that did not have the fast growth characteristics of (110)/(110) grain boundaries and were more likely to trap the non-superconducting phase to some extent during growth. In contrast, the two seed crystals on the right side are in a standard 45 ° arrangement. Fig. 4 shows the seed position and growth process for two growth modes.
Based on the advantages and disadvantages of the 45-degree arrangement mode of the multi-seed crystal, the invention eliminates the disadvantages of the multi-seed crystal on the premise of keeping the advantages of the multi-seed crystal, reduces the using amount of the seed crystal and greatly reduces the cost. Specifically, through the use of the seed crystal bridge, a single seed crystal has the capability of simultaneously inducing a plurality of buffer layers, and the buffer layers can play the role of secondary seed crystals after the buffer layers are completely grown to continuously induce the precursor. At this time, the precursor is induced by a plurality of buffer layers at the same time, and the effect of multiple seed crystals is achieved. On the other hand, just as the buffer layers are all induced from the same seed by growth, there is a fixed, consistent (110)// (110) orientation between the buffer layers, thus avoiding the most influential manual defects in the 45 alignment. Thus, the two advantages of the most important ability to grow rapidly and the "clean" grain boundaries in 45 ° alignment are also ensured. FIGS. 5-8 show top and cross-sectional views, respectively, of a sample in which single seed bridge structure achieves (110)/110 orientation induction. In FIGS. 5-6, 501 and 601 represent equilibrium shapes of domain tendencies in the states shown, 502 and 602 represent clean (110)/(110) grain boundaries obtained using the method of the present invention, and arrows 503 and 603 represent the direction in which the growth front advances. In FIGS. 7 to 8, 701 and 801 represent thin film seeds, 702 and 802 represent seed bridges, and 703 and 803 represent buffer layers. The difference between the use of 2 and 3 buffer layers is also shown in the figure, and obviously, under the same growth time, the equilibrium crystal face shape obtained by using 3 buffer layers is larger, which is also beneficial to the preparation of the block material with larger size. It is worth mentioning that the single seed bridge structure does not achieve the object of the present invention when 4 buffer layers are used, as the final multiple buffer layers will form (100)/(100) grain boundaries instead of (110)/(110) grain boundaries due to the centrosymmetric arrangement, as shown in fig. 9.
Based on the concept, the invention provides a method for realizing (110)// 110 orientation-induced growth of REBCO superconducting bulk material by using a single-seed crystal bridge structure, which comprises the following steps:
step one, RE is added according to the proportion of RE, Ba, Cu and 2:3 and RE, Ba, Cu and 2:1:12O3，BaCO3And CuO powder to prepare the original powder of RE123 and RE 211;
and step two, fully and uniformly mixing the original powder, and sintering for 48 hours at 900 ℃ in an air environment. In order to ensure that the RE123 and RE211 phases with uniform and single components are finally obtained, the sintered powder is ground and sintered again, and the same process is repeated for three times.
Step three, the obtained pure-phase powder is prepared according to RE123+30 mol% RE211+1 wt% CeO2The components are mixed, fully milled and uniformly mixed to obtain precursor powder.
And step four, weighing the powder according to different diameters of the molds, putting the powder into the molds, and pressing the powder into 1 seed crystal bridge, 2-3 buffer layers and 1 precursor in a cylindrical shape.
And fifthly, placing the seed crystal, the seed crystal bridge, the buffer layer and the precursor in sequence from top to bottom according to the layers.
And sixthly, placing the placed precursor and the single-seed crystal bridge structure in a growth furnace to perform top seed crystal melt texture growth.
The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. The following examples are not to be construed as limiting the invention.
Example one
The method for realizing (110)// 110 orientation-induced growth of the YBCO superconducting bulk material by using the single-seed crystal bridge structure comprises the following steps:
1. the ratio of Y to Ba to Cu to 1:2:3 and Y to Ba to Cu to 2:1:12O3，BaCO3And CuO powder to give raw powders of Y123 and Y211;
2. the original powder is fully and uniformly mixed and sintered for 48 hours at 900 ℃ in an air environment. In order to ensure that the Y123 and Y211 phases with uniform and single components are finally obtained, the sintered powder is ground and sintered again, and the same process is repeated for three times.
3. The pure-phase powder obtained was according to Y123+30 mol% Y211+1 wt% CeO2The components are mixed, fully milled and uniformly mixed to obtain precursor powder.
4. And weighing the powder according to different diameters of the die, putting the powder into the die, and pressing into 1 seed crystal bridge, 2-3 buffer layers and 1 precursor in a cylindrical shape. The diameter of the seed crystal bridge is 10mm, and 0.6g of seed crystal bridge is generally weighed and pressed; the diameter of the buffer layer is 5mm, and 0.15-0.2 g of buffer layer is generally weighed and pressed; the diameter of the precursor was 30mm, and 30g was weighed.
5. And placing the seed crystal, the seed crystal bridge, the buffer layer and the precursor in sequence from top to bottom according to the layers. Specifically, a C-axis oriented NdBCO/YBCO/MgO thin film seed crystal with the size of 2mm multiplied by 2mm is placed at the center of the upper surface of a seed crystal bridge, and a buffer layer is arranged in a row along the crystal direction of the seed crystal [110] (namely, on an extension line of the crystal direction of the seed crystal [110 ]).
6. And placing the placed precursor and the single-seed crystal bridge structure in a growth furnace to perform top seed crystal melt texture growth. The specific temperature program of the growth furnace is as follows:
a. the temperature is raised to 900 ℃ after 4h from the room temperature, and the temperature is kept for 4 h.
b. Heating for 1h, heating to 1065 deg.C, and maintaining for 1 h.
c. And rapidly cooling to 1005 ℃ within 30 min.
d. Slowly cooling at a cooling speed of 0.3 ℃/h to grow for 100 h.
e. Rapidly cooling along with the furnace within 4h to prepare (110)/YBCO high-temperature superconducting blocks induced by (110) orientation.
Example two
The method for realizing (110)/110 oriented induction growth of the GdBCO superconducting bulk material by using the single seed crystal bridge structure comprises the following steps:
1. gd is added according to the proportion of Gd to Ba to Cu to 1:2:3 and Gd to Ba to Cu to 2:1:12O3，BaCO3And CuO powder to prepare raw powder of Gd123 and Gd 211;
2. the original powder is fully and uniformly mixed and sintered for 48 hours at 900 ℃ in an air environment. In order to ensure that the Gd123 and Gd211 phases with uniform and single components are finally obtained, the sintered powder is ground and sintered again, and the same process is repeated for three times.
3. The pure phase powder obtained was then purified according to Gd123+30 mol% Gd211+1 wt% CeO2The components are mixed, fully milled and uniformly mixed to obtain precursor powder.
4. And weighing the powder according to different diameters of the die, putting the powder into the die, and pressing into 1 seed crystal bridge, 2-3 buffer layers and 1 precursor in a cylindrical shape. The diameter of the seed crystal bridge is 10mm, and 0.6g of seed crystal bridge is generally weighed and pressed; the diameter of the buffer layer is 5mm, and 0.15-0.2 g of buffer layer is generally weighed and pressed; the diameter of the precursor was 30mm, and 30g was weighed.
5. And placing the seed crystal, the seed crystal bridge, the buffer layer and the precursor in sequence from top to bottom according to the layers. Specifically, a C-axis oriented NdBCO/YBCO/MgO thin film seed crystal with the size of 2mm multiplied by 2mm is placed at the center of the upper surface of a seed crystal bridge, and a buffer layer is arranged in a row along the crystal direction of the seed crystal [110] (namely, on an extension line of the crystal direction of the seed crystal [110 ]).
6. And placing the placed precursor and the single-seed crystal bridge structure in a growth furnace to perform top seed crystal melt texture growth. The specific temperature program of the growth furnace is as follows:
a. the temperature is raised to 900 ℃ after 4h from the room temperature, and the temperature is kept for 4 h.
b. Heating for 1h, heating to 1095 deg.C, and maintaining for 1 h.
c. Quickly cooling to 1045 deg.C within 30 min.
d. Slowly cooling at a cooling speed of 0.3 ℃/h to grow for 100 h.
e. Rapidly cooling along with the furnace within 4h to prepare (110)// (110) orientation-induced GdBCO high-temperature superconducting bulk material.
EXAMPLE III
The method for realizing (110)/110 oriented induced growth of SmBCO superconducting bulk material by using the single seed crystal bridge structure comprises the following steps:
1. the ratio of Sm to Ba to Cu is 1:2:3 and Sm to Ba to Cu is 2:1:12O3，BaCO3And CuO powder are prepared into original powder of Sm123 and Sm 211;
2. the original powder is fully and uniformly mixed and sintered for 48 hours at 900 ℃ in an air environment. In order to ensure that the Sm123 and Sm211 phases with uniform and single components are finally obtained, the sintered powder is ground and sintered again, and the same process is repeated for three times.
3. The pure phase powder obtained was Sm123+30 mol% Sm211+1 wt% CeO2The components are mixed, fully milled and uniformly mixed to obtain precursor powder.
4. And weighing the powder according to different diameters of the die, putting the powder into the die, and pressing into 1 seed crystal bridge, 2-3 buffer layers and 1 precursor in a cylindrical shape. The diameter of the seed crystal bridge is 10mm, and 0.6g of seed crystal bridge is generally weighed and pressed; the diameter of the buffer layer is 5mm, and 0.15-0.2 g of buffer layer is generally weighed and pressed; the diameter of the precursor was 30mm, and 30g was weighed.
5. And placing the seed crystal, the seed crystal bridge, the buffer layer and the precursor in sequence from top to bottom according to the layers. Specifically, a C-axis oriented NdBCO/YBCO/MgO thin film seed crystal with the size of 2mm multiplied by 2mm is placed at the center of the upper surface of a seed crystal bridge, and a buffer layer is arranged in a row along the crystal direction of the seed crystal [110] (namely, on an extension line of the crystal direction of the seed crystal [110 ]).
6. And placing the placed precursor and the single-seed crystal bridge structure in a growth furnace to perform top seed crystal melt texture growth. The specific temperature program of the growth furnace is as follows:
a. the temperature is raised to 900 ℃ after 4h from the room temperature, and the temperature is kept for 4 h.
b. Heating for 1h, heating to 1100 deg.C, and maintaining for 1 h.
c. Quickly cooling to 1065 deg.C within 30 min.
d. Slowly cooling at a cooling speed of 0.3 ℃/h to grow for 100 h.
e. Rapidly cooling along with the furnace within 4h to prepare (110)/110 orientation-induced SmBCO high-temperature superconducting bulk.
Example four
The method for realizing (110)// (110) oriented induction growth of the NdBCO superconducting bulk material by using the single-seed bridge structure comprises the following steps:
1. nd is mixed according to the proportion of Nd Ba to Cu being 1:2:3 and Nd to Ba to Cu being 4:2:22O3，BaCO3And CuO powder are prepared into original powder of Nd123 and Nd 211;
2. the original powder is fully and uniformly mixed and sintered for 48 hours at 900 ℃ in an air environment. In order to ensure that Nd123 and Nd211 phases with uniform and single components are finally obtained, the sintered powder is ground and sintered again, and the same process is repeated for three times.
3. The resulting pure-phase powder was treated with Nd123+30 mol% Nd211+1 wt% CeO2The components are mixed, fully milled and uniformly mixed to obtain precursor powder.
4. And weighing the powder according to different diameters of the die, putting the powder into the die, and pressing into 1 seed crystal bridge, 2-3 buffer layers and 1 precursor in a cylindrical shape. The diameter of the seed crystal bridge is 10mm, and 0.6g of seed crystal bridge is generally weighed and pressed; the diameter of the buffer layer is 5mm, and 0.15-0.2 g of buffer layer is generally weighed and pressed; the diameter of the precursor was 30mm, and 30g was weighed.
5. And placing the seed crystal, the seed crystal bridge, the buffer layer and the precursor in sequence from top to bottom according to the layers. Specifically, a C-axis oriented NdBCO/YBCO/MgO thin film seed crystal with the size of 2mm multiplied by 2mm is placed at the center of the upper surface of a seed crystal bridge, and a buffer layer is arranged in a row along the crystal direction of the seed crystal [110] (namely, on an extension line of the crystal direction of the seed crystal [110 ]).
6. And placing the placed precursor and the single-seed crystal bridge structure in a growth furnace to perform top seed crystal melt texture growth. The specific temperature program of the growth furnace is as follows:
a. the temperature is raised to 900 ℃ after 4h from the room temperature, and the temperature is kept for 4 h.
b. Heating for 1h, heating to 1120 ℃, and keeping the temperature for 1 h.
c. And rapidly cooling to 1090 ℃ within 30 min.
d. Slowly cooling at a cooling speed of 0.3 ℃/h to grow for 100 h.
e. Rapidly cooling along with the furnace within 4h to prepare (110)/NdBCO high-temperature superconducting blocks induced by (110) orientation.
The invention provides a method for realizing (110)/110 oriented induction growth of REBCO high-temperature superconducting bulk by using a film seed crystal combined bridge structure. The invention utilizes the seed crystal bridge and the buffer layer to form a bridge type seed crystal structure, realizes the effect of multi-seed crystal by using single seed crystal, and achieves the effect of accelerating growth. Meanwhile, the lower buffer layer adopts a specific arrangement mode along the crystal direction of [110] to realize the (110)/(110) orientation induced growth of the buffer layer to the bulk material. Because the (110) crystal face is a rapid growth face, the structure can further accelerate the growth of the bulk material on the basis of multiple seed crystals, and the preparation time of the large-size superconducting bulk material is shortened. Because the (110)/(110) grain boundary is not easy to accumulate high-temperature phase or impurities, the influence of residual non-superconducting phase on the superconducting performance of the sample (100)/(100) grain boundary can be eliminated, and the performance of the bulk is improved.
The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.