CN102925954A - Method for preparing single domain yttrium barium copper oxide superconduction block - Google Patents

Abstract

The invention relates to a method for preparing monodomain yttrium-barium-copper-oxygen superconducting bulk material by top seed crystal infiltration method, which is to make the whole infiltration The growth process only needs a precursor powder of BaCuO ₂ , which simplifies the experimental link, shortens the experimental period, reduces the experimental cost, and improves the efficiency. Moreover, the product of the present invention has a large magnetic levitation force, and the size of the liquid phase block and the solid phase are adopted. The size of the precursor block is slightly larger or equal to the assembly method, which is beneficial to prevent the loss of the liquid phase, the collapse of the sample, and the full contact between the solid phase and the liquid phase, which is conducive to the growth of the crystal and is easy to grow directional.

Description

Method for preparing single-domain yttrium-barium-copper-oxygen superconducting bulk material by top seed crystal infiltration method

technical field

The invention belongs to the technical field of high-temperature copper oxide superconducting materials, and in particular relates to the preparation of monodomain yttrium-barium-copper-oxygen superconducting block materials by a top seed crystal infiltration growth method.

Background technique

Monodomain copper oxide high temperature superconducting bulk material (RE-Ba-Cu-O, where RE is a rare earth element, such as Nd, Gd, Y, etc.) has a high critical temperature and critical current density, and has a strong magnetic field Strong flux pinning capability. This advantage has laid the foundation for the application of this type of material in magnetic levitation technology, especially in the development of superconducting magnetic levitation bearings, energy storage flywheels, and superconducting motors and generators. In the process of preparing single-domain copper oxide superconducting bulk materials, there are two main applications, one is the traditional top-seed melt texture growth process, and the other is the top-seed growth process developed in recent years. crystal infiltration growth process.

Since the top seed infiltration growth process was invented, more and more researchers have paid attention to it, because it can effectively solve the problems existing in the traditional melt texture growth process, such as sample shrinkage, deformation, and the presence of a large number of Pores and macro cracks, severe liquid phase loss, local segregation of Y ₂ BaCuO ₅ particles, etc. In the infiltration growth process, three equal-diameter precursor blocks are used, including Y ₂ BaCuO ₅ precursor block, liquid phase block and support block. The Y ₂ BaCuO ₅ precursor block is composed of Y ₂ BaCuO ₅ precursor powder is pressed, and the liquid phase block is composed of YBa ₂ Cu ₃ O _7-x and Ba ₃ Cu ₅ O ₈ in equimolar ratio (Ba ₃ Cu ₅ O ₈ is the molar ratio of BaCuO ₂ to CuO is 3:2 The mixture) is mixed and pressed, and the support block is directly pressed from the primary powder oxide Y ₂ O ₃ . Before the heat treatment, the liquid phase block is first placed on the support block, and then the Y ₂ BaCuO ₅ precursor block is placed on the liquid phase block. During heat treatment, the Ba and Cu-rich liquid phase in the liquid phase block melts and penetrates into the Y ₂ BaCuO ₅ precursor block above under the action of capillary attraction. In the subsequent slow cooling process, this liquid phase and the precursor The Y ₂ BaCuO ₅ phase of the block reacts to form the YBa ₂ Cu ₃ O _7-x phase, and the orderly growth of the YBa ₂ Cu ₃ O _7-x grains is completed under the induction of the seed crystal. During the heat treatment, the support block will also absorb part of the liquid phase, forming most of the Y ₂ BaCuO ₅ phase and a small amount of YBa ₂ Cu ₃ O _7-x phase. Due to the existence of a large number of Y ₂ BaCuO ₅ solid particles, the support block can support the two pioneer blocks above at high temperature, keep them upright during heat treatment, and prevent the loss of liquid phase. It can be seen that the top seed infiltration growth method is a more complicated and time-consuming preparation method than the traditional method. This preparation method uses three precursor powders (Y ₂ BaCuO ₅ , YBa ₂ Cu ₃ O _{7- x} , BaCuO ₂ ), each precursor powder is prepared by the traditional solid-state reaction method, that is, through repeated high-temperature calcination and grinding to obtain a precursor powder with pure phase, low carbon content and small particle size (0.1-10 microns), each All the powders need at least one week, so the whole preparation method takes a long time, the work efficiency is low, and the cost of the experiment is increased.

Contents of the invention

In order to overcome the technical problems of long preparation time and high process cost, the invention provides a kind of Only one kind of BaCuO ₂ precursor powder needs to be prepared in advance to meet the needs of preparing solid-phase source and liquid-phase source powder, and the prepared single-domain yttrium-barium-copper-oxygen superconducting block has high magnetic levitation force and is easy to use for directional growth. A method for preparing single-domain yttrium-barium-copper-oxygen superconducting bulk material by top seed crystal infiltration method.

The technical solution adopted to solve the above technical problems consists of the following steps:

(1) Preparation of solid phase precursor powder

Mix BaCO ₃ and CuO in a molar ratio of 1:1, make BaCuO ₂ powder by solid state reaction method, mix the initial Y ₂ O ₃ powder and BaCuO ₂ powder in a molar ratio of 1:x, and make (Y ₂ O ₃ +x BaCuO ₂ ) solid phase precursor powder;

In the above formula, 0.5≤x≤3;

(2) Preparation of liquid source powder

Mix BaCO ₃ and CuO in a molar ratio of 1:1, and sinter it into BaCuO ₂ powder by solid state reaction method. The molar ratio of Y ₂ O ₃ or Yb ₂ O ₃ initial powder to CuO and BaCuO ₂ powder is 1:6: 10 mix evenly, as liquid phase source powder;

(3) Press solid phase precursor block and liquid phase block

Take (Y ₂ O ₃ +x BaCuO ₂ ) solid-phase precursor powder and liquid-phase source powder, and press them into (Y ₂ O ₃ +x BaCuO ₂ ) solid-phase precursor block and liquid-phase block respectively, and solid-phase precursor powder and liquid-phase The mass ratio of source powder is 1:0.72～1.93;

(4) Press the support block

Press Y ₂ O ₃ powder or Yb ₂ O ₃ powder into a block with the same shape as the liquid phase block as a support block;

(5) Preparation of neodymium barium copper oxide seed crystal block

Mix Nd ₂ O ₃ with BaCO ₃ and CuO, the molar ratio of Nd ₂ O ₃ to BaCO ₃ and CuO is 1:1:1, and make Nd ₂ BaCuO ₅ powder by solid state reaction method; take Nd ₂ O ₃ and BaCO ₃ , CuO mixed, the molar ratio of Nd ₂ O ₃ to BaCO ₃ , CuO is 1:4:6, and NdBa ₂ Cu ₃ O _7-δ powder is made by solid state reaction method; Nd ₂ BaCuO ₅ powder is mixed with NdBa ₂ Cu ₃ The O _7-δ powder is mixed evenly according to the mass ratio of 1:3, and used as a precursor block, which is sintered by the top seed melt texture method, and the naturally cleaved small square is used as the NdBCO seed block;

In the above formula, 0≤δ≤1;

(6) Body assembly and placement

On the upper surface of the Al ₂ O ₃ gasket, place the MgO single wafer, the support block, the liquid phase block, the Y ₂ O ₃ +x BaCuO ₂ solid phase precursor block and the neodymium barium copper oxide seed crystal block in sequence to form a green body ;

(7) Infiltration growth monodomain yttrium barium copper oxide bulk material

Put the assembled body into a tube furnace, raise the temperature to 920°C at a heating rate of 90-120°C per hour, keep it warm for 10-20 hours, and raise the temperature to 1040-1045°C at a heating rate of 40-60°C per hour , keep warm for 1-2 hours; cool down to 1015-1020°C at a cooling rate of 50°C per hour, slowly cool to 970-990°C at a cooling rate of 0.1-0.5°C per hour, and naturally cool to room temperature with the furnace to obtain monodomain Yttrium barium copper oxide bulk material;

(8) Oxygen treatment

The single-domain yttrium-barium-copper-oxygen bulk material is placed in a quartz tube furnace, and slowly cooled in a temperature zone of 410-440° C. for 200 hours in a circulating oxygen atmosphere to obtain a single-domain yttrium-barium-copper-oxygen superconducting bulk material.

In the above step (1), BaCO ₃ and CuO are mixed in a molar ratio of 1:1, and BaCuO ₂ powder is prepared by solid state reaction method, and the initial Y ₂ O ₃ powder and BaCuO ₂ powder are mixed in a molar ratio of 1:x Mix evenly to make (Y ₂ O ₃ +x BaCuO ₂ ) solid phase precursor powder, where 1≤x≤2.5 in the above formula.

In the above step (3), take (Y ₂ O ₃ +x BaCuO ₂ ) solid-phase precursor powder and liquid-phase source powder and press them into (Y ₂ O ₃ +x BaCuO ₂ ) solid-phase precursor block and liquid-phase block respectively, The mass ratio of the solid-phase precursor powder to the liquid-phase source powder is 1:0.82-1.44.

The size of the above-mentioned liquid phase block is not smaller than the size of the solid phase block.

In the above step (6), the MgO single wafers are 3 to 5 pieces of equal height.

The method for preparing single-domain yttrium-barium-copper-oxygen superconducting bulk material with the top seed crystal infiltration method of the present invention is by changing the composition of the solid phase source powder and the liquid phase source powder used in the solid phase block, so that the whole infiltration growth process only needs _BaCuO2 is a kind of precursor powder, which simplifies the experimental link, shortens the experimental period, reduces the experimental cost, and improves the efficiency. Moreover, the product of the present invention has a large magnetic levitation force, and the size of the liquid phase block and the size of the solid phase precursor block are adopted. Compared with slightly larger or equal assembly methods, it is beneficial to prevent the loss of the liquid phase, the collapse of the sample, and the full contact between the solid phase and the liquid phase, which is beneficial to the growth of crystals and is easy to grow directional.

Description of drawings

Fig. 1 is a comparison curve of magnetic levitation force of monodomain yttrium-barium-copper-oxygen superconducting bulk materials prepared with different proportions of Y ₂ O ₃ and BaCuO ₂ .

Figure 2 is a photo of the surface morphology of the monodomain yttrium barium copper oxide superconducting bulk material prepared when the ratio of Y ₂ O ₃ to BaCuO ₂ in the solid phase precursor powder is 1:0.5.

Figure 3 is a photograph of the surface morphology of the monodomain yttrium barium copper oxide superconducting bulk material prepared when the ratio of Y ₂ O ₃ to BaCuO ₂ in the solid phase precursor powder is 1:1.0.

Figure 4 is a photograph of the surface morphology of the monodomain yttrium barium copper oxide superconducting bulk material prepared when the ratio of Y ₂ O ₃ to BaCuO ₂ in the solid phase precursor powder is 1:1.2.

Figure 5 is a photo of the surface morphology of the monodomain yttrium barium copper oxide superconducting bulk material prepared when the ratio of Y ₂ O ₃ to BaCuO ₂ in the solid phase precursor powder is 1:1.5.

Fig. 6 is a photograph of the surface morphology of the monodomain yttrium barium copper oxide superconducting bulk material prepared when the ratio of Y ₂ O ₃ to BaCuO ₂ in the solid phase precursor powder is 1:1.8.

Fig. 7 is a photograph of the surface morphology of the monodomain yttrium barium copper oxide superconducting bulk material prepared when the ratio of Y ₂ O ₃ to BaCuO ₂ in the solid phase precursor powder is 1:2.

Fig. 8 is a photograph of the surface morphology of the monodomain yttrium barium copper oxide superconducting bulk material prepared when the ratio of Y ₂ O ₃ to BaCuO ₂ in the solid phase precursor powder is 1:2.5.

Fig. 9 is a photo of the surface morphology of the monodomain yttrium barium copper oxide superconducting bulk material prepared when the ratio of Y ₂ O ₃ to BaCuO ₂ in the solid phase precursor powder is 1:3.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to these embodiments.

Example 1

Taking the raw material _Y2O3 as the initial powder of solid-phase precursor powder as an example, the method _for preparing monodomain yttrium-barium-copper-oxygen superconducting bulk material by the top seed crystal infiltration method consists of the following steps:

(1) Preparation of solid phase precursor powder

Take 106.9064g BaCO ₃ and 43.0936g CuO and mix them uniformly at a molar ratio of 1:1, make BaCuO ₂ powder by solid state reaction method, mix the initial Y ₂ O ₃ powder with BaCuO ₂ powder at a molar ratio of 1:1.2, Take 100g of the mixed powder and add it to the ball mill and mix it evenly to make (Y ₂ O ₃ +1.2BaCuO ₂ ) solid phase precursor powder;

(2) Preparation of liquid source powder

Take 106.9064g BaCO ₃ and 43.0936g CuO and mix them uniformly at a molar ratio of 1:1, sinter into BaCuO ₂ powder by solid state reaction method, take 11.17g Y ₂ O ₃ initial powder and 23.61g CuO, 115.21g BaCuO ₂ The ratio is 1:6:10 and mixed evenly, as a liquid phase source powder;

(3) Press solid phase precursor block and liquid phase block

Take 9.9134g (Y ₂ O ₃ +1.2BaCuO ₂ ) solid-phase precursor powder and press it into a cylindrical (Y ₂ O ₃ +1.2BaCuO ₂ ) solid-phase precursor block with a diameter of 20mm, and take 13g of liquid-phase source powder and press it into a diameter of 30mm cylindrical liquid phase block, the mass ratio of solid phase precursor powder to liquid phase source powder is 1:1.31.

(4) Press the support block

Take 3g of Y ₂ O ₃ powder and press it into a block with the same shape as the liquid phase block as a support block;

(5) Preparation of neodymium barium copper oxide seed crystal block

Take 54.8586g Nd ₂ O ₃ , 32.1727g BaCO ₃ , and 12.9687g CuO and mix them. The molar ratio of Nd ₂ O ₃ to BaCO ₃ and CuO is 1:1:1. Use the solid state reaction method to make Nd ₂ BaCuO ₅ powder; take 20.9895 Mix g Nd ₂ O ₃ , 49.2386g BaCO ₃ , and 29.7719g CuO, the molar ratio of Nd ₂ O ₃ to BaCO ₃ and CuO is 1:4:6, and make NdBa ₂ Cu ₃ O _7-δ powder by solid state reaction method, 0≤δ≤1; mix Nd ₂ BaCuO ₅ powder and NdBa ₂ Cu ₃ O _7-δ powder evenly according to the mass ratio of 1:3, as a precursor block, use the top seed melting texture method in a tube furnace Carry out sintering in the medium, take the small square of natural cleavage as the seed crystal block of neodymium barium copper oxide;

(6) Body assembly and placement

On the upper surface of the Al ₂ O ₃ gasket, place four pieces of MgO single wafer, support block, liquid phase block, (Y ₂ O ₃ +1.2BaCuO ₂ ) solid phase precursor block and neodymium barium copper oxide seed crystal block in sequence from bottom to top , the heights of the four MgO single crystals are the same, and the neodymium barium copper oxide seed crystal block is located at the center of the upper surface of the (Y ₂ O ₃ +1.2BaCuO ₂ ) solid phase precursor block to form a green body.

(7) Infiltration growth monodomain yttrium barium copper oxide bulk material

Put the assembled body into a tube furnace, raise the temperature to 920°C at a heating rate of 100°C per hour, keep it warm for 15 hours, raise the temperature to 1042°C at a heating rate of 50°C per hour, and keep it warm for 2 hours; Cool down to 1018°C at a cooling rate of 50°C, slowly cool to 980°C at a cooling rate of 0.4°C per hour, and cool naturally to room temperature with the furnace to obtain a monodomain yttrium barium copper oxide block.

(8) Oxygen treatment

The single-domain yttrium-barium-copper-oxygen bulk material is placed in a quartz tube furnace, and slowly cooled in a temperature range of 440-410° C. for 200 hours in a circulating oxygen atmosphere to obtain a single-domain yttrium-barium-copper-oxygen superconducting bulk material.

For the single-domain yttrium-barium-copper-oxygen superconducting bulk material prepared above, its magnetic levitation force was measured using a three-dimensional magnetic field and magnetic force testing device. The diameter of the permanent magnet used in the test was 20mm, the surface magnetic field strength was 0.5T, and the test temperature was 77K. The magnetic levitation force is 46.89916N.

Example 2

Taking the raw material _Y2O3 powder used as the initial powder of the solid-phase precursor powder as an example, the method for preparing monodomain yttrium _- barium-copper-oxygen superconducting bulk material with the top seed crystal infiltration method consists of the following steps:

(1) Preparation of solid phase precursor powder

Take 106.9064g BaCO ₃ and 43.0936g CuO and mix them uniformly at a molar ratio of 1:1, make BaCuO ₂ powder by solid state reaction method, mix the initial Y ₂ O ₃ powder with BaCuO ₂ powder at a molar ratio of 1:1, Take 100g of the mixed powder and add it to the ball mill and mix it evenly to make (Y ₂ O ₃ +BaCuO ₂ ) solid phase precursor powder;

(2) Preparation of liquid source powder

Take 106.9064g of _{BaCO 3} and _43.0936g of CuO in _{a molar ratio of 1:1 and mix them evenly, and sinter them into BaCuO 2 powder} by solid state reaction method. Mix evenly at a ratio of 1:6:1, and use it as a liquid phase source powder;

(3) Press solid phase precursor block and liquid phase block

Take 9g (Y ₂ O ₃ +BaCuO ₂ ) solid-phase precursor powder and press it into a cylinder-shaped Y ₂ O ₃ +BaCuO ₂ solid-phase precursor block with a diameter of 20mm; Phase block, the mass ratio of solid phase precursor powder to liquid phase source powder is 1:1.44.

(4) Press the support block

Take 3g of Y ₂ O ₃ powder and press it into a block with the same shape as the liquid phase block as a support block;

(5) Preparation of neodymium barium copper oxide seed crystal block

Take 54.8586g Nd ₂ O ₃ , 32.1727g BaCO ₃ , and 12.9687g CuO and mix them. The molar ratio of Nd ₂ O ₃ to BaCO ₃ and CuO is 1:1:1. Use the solid state reaction method to make Nd ₂ BaCuO ₅ powder; take 20.9895 Mix g Nd ₂ O ₃ , 49.2386g BaCO ₃ , and 29.7719g CuO, the molar ratio of Nd ₂ O ₃ to BaCO ₃ and CuO is 1:4:6, and make NdBa ₂ Cu ₃ O _7-δ powder by solid state reaction method, 0≤δ≤1; mix Nd ₂ BaCuO ₅ powder and NdBa ₂ Cu ₃ O _7-δ powder evenly according to the mass ratio of 1:3, as a precursor block, use the top seed melting texture method in a tube furnace Carry out sintering in the medium, take the small square of natural cleavage as the seed crystal block of neodymium barium copper oxide;

(6) Body assembly and placement

Place four MgO single wafers, support block, liquid phase block, (Y ₂ O ₃ +BaCuO ₂ ) solid phase precursor block and neodymium barium copper oxide seed crystal block sequentially on the upper surface of the Al ₂ O ₃ gasket from bottom to top, The heights of the four MgO single crystals are the same, and the neodymium barium copper oxide seed crystal block is located at the center of the upper surface of the (Y ₂ O ₃ +BaCuO ₂ ) solid phase precursor block.

The other steps were the same as in Example 1 to obtain a single-domain yttrium-barium-copper-oxygen superconducting bulk material.

Example 3

Taking the raw material _Y2O3 powder used as the initial powder of the solid-phase precursor powder as an example, the method for preparing monodomain yttrium _- barium-copper-oxygen superconducting bulk material with the top seed crystal infiltration method consists of the following steps:

(1) Preparation of solid phase precursor powder

Take 106.9064g BaCO ₃ and 43.0936g CuO and mix them uniformly at a molar ratio of 1:1, make BaCuO ₂ powder by solid state reaction method, mix the initial Y ₂ O ₃ powder and BaCuO ₂ powder at a molar ratio of 1:2.5, Take 100g of the mixed powder and add it to the ball mill and mix it evenly to make (Y ₂ O ₃ +2.5BaCuO ₂ ) solid phase precursor powder;

(2) Preparation of liquid source powder

Take 106.9064g of _{BaCO 3} and _43.0936g of CuO in _{a molar ratio of 1:1 and mix them evenly, and sinter them into BaCuO 2 powder} by solid state reaction method. Mix evenly at a ratio of 1:6:1, and use it as a liquid phase source powder;

(3) Press solid phase precursor block and liquid phase block

Take 15.8531g (Y ₂ O ₃ +2.5BaCuO ₂ ) solid phase precursor powder and press it into a cylindrical (Y ₂ O ₃ +2.5BaCuO ₂ ) solid phase precursor block with a diameter of 20mm, weigh 13g of the liquid phase source powder and press it into a diameter It is a 30mm cylindrical liquid phase block, and the mass ratio of solid phase precursor powder to liquid phase source powder is 1:0.82.

(4) Press the support block

Take 3g of Y ₂ O ₃ powder and press it into a block with the same shape as the liquid phase block as a support block;

(5) Preparation of neodymium barium copper oxide seed crystal block

Take 54.8586g Nd ₂ O ₃ , 32.1727g BaCO ₃ , and 12.9687g CuO and mix them. The molar ratio of Nd ₂ O ₃ to BaCO ₃ and CuO is 1:1:1. Use the solid state reaction method to make Nd ₂ BaCuO ₅ powder; take 20.9895 Mix g Nd ₂ O ₃ , 49.2386g BaCO ₃ , and 29.7719g CuO, the molar ratio of Nd ₂ O ₃ to BaCO ₃ and CuO is 1:4:6, and make NdBa ₂ Cu ₃ O _7-δ powder by solid state reaction method, 0≤δ≤1; mix Nd ₂ BaCuO ₅ powder and NdBa ₂ Cu ₃ O _7-δ powder evenly according to the mass ratio of 1:3, as a precursor block, use the top seed melting texture method in a tube furnace Carry out sintering in the medium, take the small square of natural cleavage as the seed crystal block of neodymium barium copper oxide;

(6) Body assembly and placement

On the upper surface of the Al ₂ O ₃ gasket, place four pieces of MgO single wafer, support block, liquid phase block, (Y ₂ O ₃ +2.5BaCuO ₂ ) solid phase precursor block and neodymium barium copper oxide seed crystal block in sequence from bottom to top , the heights of the four MgO single crystals are the same, and the NdBCO seed crystal block is located at the center of the upper surface of the (Y ₂ O ₃ +2.5BaCuO ₂ ) solid phase precursor block.

The other steps were the same as in Example 1 to obtain a single-domain yttrium-barium-copper-oxygen superconducting bulk material.

Example 4

Taking the raw material _Y2O3 powder used as the initial powder of the solid-phase precursor powder as an example, the method for preparing monodomain yttrium _- barium-copper-oxygen superconducting bulk material with the top seed crystal infiltration method consists of the following steps:

(1) Preparation of solid phase precursor powder

Take 106.9064g BaCO ₃ and 43.0936g CuO and mix them uniformly at a molar ratio of 1:1, make BaCuO ₂ powder by solid state reaction method, mix the initial Y ₂ O ₃ powder with BaCuO ₂ powder at a molar ratio of 1:0.5, Take 100g of the mixed powder and add it to the ball mill and mix it evenly to make (Y ₂ O ₃ +0.5BaCuO ₂ ) solid phase precursor powder;

(2) Preparation of liquid source powder

Take 106.9064g of _{BaCO 3} and _43.0936g of CuO in _{a molar ratio of 1:1 and mix them evenly, and sinter them into BaCuO 2 powder} by solid state reaction method. Mix evenly at a ratio of 1:6:1, and use it as a liquid phase source powder;

(3) Press solid phase precursor block and liquid phase block

Take 6.7150g (Y ₂ O ₃ +0.5BaCuO ₂ ) solid phase precursor powder and press it into a cylindrical (Y ₂ O ₃ +0.5BaCuO ₂ ) solid phase precursor block with a diameter of 20mm, weigh 13g of the liquid phase source powder and press it into a diameter It is a 30mm cylindrical liquid phase block, and the mass ratio of solid phase precursor powder to liquid phase source powder is 1:1.93.

The other steps were the same as in Example 1 to obtain a single-domain yttrium-barium-copper-oxygen superconducting bulk material.

Example 5

Taking the raw material _Y2O3 powder used as the initial powder of the solid-phase precursor powder as an example, the method for preparing monodomain yttrium _- barium-copper-oxygen superconducting bulk material with the top seed crystal infiltration method consists of the following steps:

(1) Preparation of solid phase precursor powder

Take 106.9064g BaCO ₃ and 43.0936g CuO and mix them uniformly at a molar ratio of 1:1, make BaCuO ₂ powder by solid state reaction method, mix the initial Y ₂ O ₃ powder and BaCuO ₂ powder at a molar ratio of 1:3, Take 100g of the mixed powder and add it to the ball mill and mix it evenly to make (Y ₂ O ₃ +3BaCuO ₂ ) solid phase precursor powder;

(2) Preparation of liquid source powder

Take 106.9064g BaCO ₃ and _43.0936g CuO and mix them uniformly at a molar ratio of 1:1 _, and sinter them into BaCuO ₂ powder by solid state reaction method _. 1:6:10 mixed evenly, as liquid phase source powder;

(3) Press solid phase precursor block and liquid phase block

Take 18.1376g (Y ₂ O ₃ +3BaCuO ₂ ) solid phase precursor powder and press it into a cylindrical (Y ₂ O ₃ +3BaCuO ₂ ) solid phase precursor block with a diameter of 20mm, weigh 13g and take the liquid phase source powder and press it into a diameter of 30mm The cylinder-shaped liquid block, the mass ratio of solid phase precursor powder to liquid phase source powder is 1:0.72.

The other steps were the same as in Example 1 to obtain a single-domain yttrium-barium-copper-oxygen superconducting bulk material.

Example 6

In the method for preparing monodomain yttrium-barium-copper-oxide superconducting bulk material by using the top seed infiltration method in the above-mentioned embodiments 1-5, in step (6), on the upper surface of the Al ₂ O ₃ gasket from bottom to top, Place 3 MgO single wafers, support block, liquid phase block, solid phase precursor block and NdBCO seed crystal block, the height of the 3 MgO single wafers is the same, and the NdBCO seed crystal block is located on the upper surface of the solid phase precursor block The other operations in this step are the same as those in the corresponding embodiment. In step (7), put the assembled green body into a tube furnace, raise the temperature to 920°C at a heating rate of 90°C per hour, keep the temperature for 20 hours, and raise the temperature to 1040°C at a heating rate of 40°C per hour. Keep warm for 2 hours; cool down to 1015°C at a cooling rate of 50°C per hour, slowly cool to 970°C at a cooling rate of 0.1°C per hour, and naturally cool to room temperature with the furnace to obtain a monodomain yttrium barium copper oxide block. The other steps are the same as those in the corresponding embodiments to obtain monodomain yttrium barium copper oxide superconducting bulk material.

Example 7

In the method for preparing monodomain yttrium-barium-copper-oxide superconducting bulk material by using the top seed infiltration method in the above-mentioned embodiments 1-5, in step (6), on the upper surface of the Al ₂ O ₃ gasket from bottom to top, Place 5 pieces of MgO single wafer, support block, liquid phase block, solid phase precursor block and NdBCO seed crystal block, the height of the 5 MgO single wafers is the same, and the NdBCO seed crystal block is located on the upper surface of the solid phase precursor block The other operations in this step are the same as those in the corresponding embodiment. In step (7), put the assembled green body into a tube furnace, raise the temperature to 920°C at a heating rate of 120°C per hour, keep the temperature for 10 hours, and raise the temperature to 1045°C at a heating rate of 60°C per hour. Insulate for 1 hour; cool down to 1020°C at a cooling rate of 50°C per hour, slowly cool to 990°C at a cooling rate of 0.5°C per hour, and naturally cool to room temperature with the furnace to obtain a monodomain yttrium barium copper oxide block. The other steps are the same as those in the corresponding embodiments to obtain monodomain yttrium barium copper oxide superconducting bulk material.

Example 8

In the method for preparing monodomain yttrium-barium-copper-oxide superconducting bulk material by top seed crystal infiltration method in the above-mentioned embodiments 1-7, in step (2), Y ₂ O ₃ starting powder is used with an equimolar amount of Yb ₂ O ₃ replacement, mixed with CuO, _BaCuO2 powder at a molar ratio of 1:6:10, as a liquid phase source powder; other operations and other steps in this step are the same as the corresponding examples, to obtain monodomain yttrium barium Copper oxide superconducting bulk.

Example 9

In the method for preparing monodomain yttrium-barium-copper-oxide superconducting bulk material by using the top seed infiltration method in the above-mentioned embodiments 1-8, in step (3), the solid-phase precursor powder is pressed into a cylindrical solid with a diameter of 25 mm. Phase precursor block, take the liquid phase source powder and press it into a cylindrical liquid phase block with a diameter of 35mm to ensure that the size of the liquid phase block is not less than the size of the solid phase precursor block, and other steps are the same as in the corresponding embodiments to obtain monodomain Yttrium barium copper oxide superconducting bulk.

Example 10

In the method for preparing monodomain yttrium-barium-copper-oxide superconducting bulk material by the top seed crystal infiltration method in the above-mentioned embodiments 1-9, in step (4), the raw material Y ₂ O ₃ powder used can be _Yb 2 O 3 powder of equal mass O ₃ powder was replaced, pressed into a support block, and the other steps were the same as those in the corresponding embodiments to obtain a single-domain yttrium-barium-copper-oxygen superconducting block.

In order to determine the optimal raw material ratio of the present invention, the inventor has carried out a large number of laboratory research experiments, among which determine the effect of different ratios of _Y2O3 and _BaCuO2 on the morphology and magnetic levitation force of monodomain yttrium-barium-copper-oxygen _{superconducting} bulk materials The impact of the experiment is as follows:

According to the process condition test in Example 1, prepare (Y ₂ O ₃ +x BaCuO ₂ ) solid-phase precursor powder in step 1, mix BaCO ₃ and CuO in a molar ratio of 1:1, and make BaCuO by solid-state reaction method ₂ powder, mix the initial Y ₂ O ₃ powder and BaCuO ₂ powder in a molar ratio of Y ₂ O ₃ : BaCuO ₂ =1:x, and make (Y ₂ O ₃ +x BaCuO ₂ ) as a solid-phase precursor powder. x is 0.5, 1, 1.2, 1.5, 1.8, 2, 2.5, 3, respectively, mixed uniformly, prepared into a solid phase precursor powder, other steps are the same as in Example 1, prepared into a single-domain yttrium-barium-copper-oxygen superconductor with a diameter of 20mm blocks.

(1) The magnetic levitation force of the prepared single-domain yttrium-barium-copper-oxygen superconducting bulk materials was tested with a three-dimensional magnetic field and a magnetic force testing device, and the test results are shown in Figure 1.

In Fig. 1, curve a is the magnetic levitation force curve of single-domain yttrium-barium-copper-oxygen superconducting bulk material with x=0.5, and curve b is the magnetic levitation force curve of single-domain yttrium-barium-copper-oxygen superconducting bulk material with x=1.0, and the curve c is the magnetic levitation force curve of the monodomain yttrium barium copper oxide superconducting bulk material when x=1.2, the curve d is the magnetic levitation force curve of the single domain yttrium barium copper oxygen superconducting bulk material when x=1.5, and the curve e is x= The magnetic levitation force curve of single domain yttrium barium copper oxide superconducting bulk material at 1.8, the curve f is the magnetic levitation force curve of single domain yttrium barium copper oxygen superconducting bulk material at x=2, and the curve g is the single domain yttrium barium copper oxygen superconducting bulk material at x=2.5 The magnetic levitation force curve of the domain yttrium barium copper oxide superconducting bulk material, the curve h is the magnetic levitation force curve of the single domain yttrium barium copper oxygen superconducting bulk material when x=3. Z in the figure is the distance between the permanent magnet and the single-domain YBCO superconducting block, and the ratio of the magnetic levitation force to the upper surface area of the single-domain YBCO superconducting block (the diameter of the upper surface is 20mm) is the magnetic levitation force density, as shown in Fig. 1 It can be seen that the molar ratio of Y ₂ O ₃ initial powder and BaCuO ₂ powder is Y ₂ O ₃ : BaCuO ₂ =1: x, and the solid phase precursor powder is uniformly prepared by mixing, and x is 0.5, 1.0, 1.2, 1.5, 1.8 respectively , 2.0, 2.5, and 3.0 refer to the maximum magnetic levitation force of the YBCO superconducting bulk material prepared respectively 3.14805N, 44.12318N, 46.89916N, 44.25472N, 34.25446N, 29.48641N, 22.20067N, 10.23915N, thus It can be seen that the magnetic levitation force is the largest when Y ₂ O ₃ : BaCuO ₂ =1:1.2, the value is 46.89916N, and the corresponding magnetic levitation force density is 14.94N/cm ² .

(2) Take the monodomain yttrium-barium-copper-oxide superconducting bulk materials prepared when the above x is 0.5, 1.0, 1.2, 1.5, 1.8, 2.0, 2.5, and 3.0, and use a camera to take pictures of their surface morphology, see Figures 2 to 3. Figure 9.

From the comparison of Fig. 2 to Fig. 9, it can be seen that when 0.5≤x<1, the yttrium-barium-copper-oxide crystals cannot cover the entire sample. With the increase of x, when 1≤x≤2, yttrium-barium-copper-oxide crystals can grow over the whole sample, with four symmetrical sectors centered on the seed crystal, with obvious cross pattern and smooth surface. When x increases further, the morphology of the sample changes slightly, and the growth area of YBCO crystals shows a decreasing trend.

The method for preparing monodomain yttrium-barium-copper-oxygen superconducting bulk material by top seed crystal infiltration method of the present invention is not limited to the above-mentioned several embodiments, and the method of the present invention can also be used to prepare other materials such as Gd, Sm, Nd, Eu, etc. series of high-temperature superconducting bulk materials.

Claims (5)

1. one kind prepares the method for single domain yttrium barium copper oxide superconductor with top seed crystal infiltration method, is comprised of following step:

(1) preparation solid phase precursor powder

With BaCO ₃With CuO in molar ratio for 1:1 mixes, make BaCuO with solid state reaction ₂Powder is with Y ₂O ₃Initial powder and BaCuO ₂Powder mixes for the ratio of 1:x in molar ratio, makes Y ₂O ₃+ x BaCuO ₂The solid phase precursor powder;

0.5≤x in the following formula≤3;

(2) preparation liquid phase source powder

With BaCO ₃With CuO in molar ratio for 1:1 mixes, sinter BaCuO into solid state reaction ₂Powder is with Y ₂O ₃Or Yb ₂O ₃Initial powder and CuO, BaCuO ₂Powder mixes for 1:6:10 in molar ratio, as the liquid phase source powder;

(3) compacting solid phase pioneer's piece and liquid phase piece

Get Y ₂O ₃+ x BaCuO ₂Solid phase precursor powder and liquid phase source powder are pressed into respectively Y ₂O ₃+ x BaCuO ₂Solid phase pioneer's piece and liquid phase piece, the mass ratio of solid phase precursor powder and liquid phase source powder is 1:0.72～1.93;

(4) compacting back-up block

With Y ₂O ₃Powder or Yb ₂O ₃Powder is pressed into and the block-shaped identical briquet of liquid phase, as back-up block;

(5) preparation Nd-Ba-Cu oxygen seed crystal blocks

Get Nd ₂O ₃With BaCO ₃, CuO mixes Nd ₂O ₃With BaCO ₃, CuO mol ratio be 1:1:1, make Nd with solid state reaction ₂BaCuO ₅Powder; Get Nd ₂O ₃With BaCO ₃, CuO mixes Nd ₂O ₃With BaCO ₃, CuO mol ratio be 1:4:6, make NdBa with solid state reaction ₂Cu ₃O _7-δPowder; With Nd ₂BaCuO ₅Powder and NdBa ₂Cu ₃O _7-δPowder is that 1:3 mixes according to mass ratio, as pioneer's piece, with top seed crystal melting texture method sintering, takes from the dice of right cleavage as the Nd-Ba-Cu oxygen seed crystal blocks;

0≤δ in the following formula≤1;

(6) base substrate assembling and placement

At Al ₂O ₃The pad upper surface to lower and on place successively MgO single-chip, back-up block, liquid phase piece, Y ₂O ₃+ x BaCuO ₂Solid phase pioneer's piece and Nd-Ba-Cu oxygen seed crystal blocks form base substrate;

(7) infiltration growth single domain yttrium, barium, copper and oxygen block

The base substrate that assembles is put into tube furnace, be warming up to 920 ℃ with 90～120 ℃ temperature rise rate per hour, be incubated 10～20 hours, be warming up to 1040～1045 ℃ with 40～60 ℃ temperature rise rate per hour, be incubated 1～2 hour; Be cooled to 1015～1020 ℃ with 50 ℃ rate of temperature fall per hour, with 0.1～0.5 ℃ rate of temperature fall slow cooling to 970 per hour～990 ℃, naturally cool to room temperature with stove, obtain single domain yttrium, barium, copper and oxygen block;

(8) oozing oxygen processes

Single domain yttrium, barium, copper and oxygen block is inserted in the quartz tube furnace, and in the circulation oxygen atmosphere, slow cooling is 200 hours in 410～440 ℃ the warm area, obtains single domain yttrium barium copper oxide superconductor.

2. according to claim 1ly prepare the method for single domain yttrium barium copper oxide superconductor with top seed crystal infiltration method, it is characterized in that: in the described step (1), with BaCO ₃With CuO in molar ratio for 1:1 mixes, make BaCuO with solid state reaction ₂Powder is with Y ₂O ₃Initial powder and BaCuO ₂Powder mixes for the ratio of 1:x in molar ratio, makes Y ₂O ₃+ x BaCuO ₂The solid phase precursor powder, 1≤x in the following formula≤2.5.

3. according to claim 1ly prepare the method for single domain yttrium barium copper oxide superconductor with top seed crystal infiltration method, it is characterized in that: in the described step (3), get Y ₂O ₃+ x BaCuO ₂Solid phase precursor powder and liquid phase source powder are pressed into respectively Y ₂O ₃+ x BaCuO ₂Solid phase pioneer's piece and liquid phase piece, the mass ratio of solid phase precursor powder and liquid phase source powder is 1:0.82～1.44.

4. according to claim 3ly prepare the method for single domain yttrium barium copper oxide superconductor with top seed crystal infiltration method, it is characterized in that: the sized blocks of described liquid phase piece is not less than the size of solid phase piece.

5. according to claim 1ly prepare the method for single domain yttrium barium copper oxide superconductor with top seed crystal infiltration method, it is characterized in that: in the described step (6), the MgO single-chip is contour 3～5.

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