CN101587763A - Method for preparing buffer layers of high-temperature superconducting coating conductors - Google Patents

Abstract

The invention discloses a preparation method of a high-temperature superconducting coating conductor buffer layer. The method introduces transition metal element manganese as a stabilizer of cubic phase zirconia, and two organic salts of manganese acetate tetrahydrate and zirconium acetylacetonate are prepared according to Mn: Zr=x:1-x (0.1≤x≤0.4) atomic ratio dissolved in organic solvent propionic acid or methanol, heated to 80-120 ° C and kept stirring to obtain a precursor solution, by spin coating or dip coating on SrTiO ₃ (100 ) single wafer or Ni-5at.%W alloy/La ₂ Zr ₂ O ₇ substrate, after high temperature crystallization, a uniform and dense Mn _x Zr _1-x O ₂ buffer layer film is obtained, and the film has a good cubic texture . The present invention adopts the chemical solution method to replace yttrium with manganese as a stabilizer based on zirconia, and the prepared Mn-SZ film can epitaxially grow a sharp cubic texture on a single crystal and other buffer layers, and the epitaxial film has good surface crystallization Spend.

Description

A kind of preparation method of high temperature superconducting coating conductor buffer layer

technical field

The invention belongs to the technical field of high-temperature superconducting coated conductors, in particular to a preparation method of a high-temperature superconducting coated conductor buffer layer.

Background technique

Coated conductor is a superconducting tape with high critical current developed based on the excellent intrinsic superconducting properties and strong anisotropy of Y-series high-temperature superconductors. Its current-carrying capacity in a strong magnetic field has exceeded other practical The superconducting material is the only practical superconducting material that can realize the application of strong magnetic field in the liquid nitrogen temperature zone. Therefore, countries around the world, especially western developed countries, have invested huge manpower and material resources in the research of coated conductors. The United States and Japan have achieved the double-hundred goals set five years ago (Ic>100A/cm, L>100m) , has now marched towards the double thousand goals (Ic>1000A/cm, L>1000m).

High temperature coated conductors are mainly composed of four parts: substrate, buffer layer, superconducting layer and protective layer. Among them, the buffer layer is used to block the chemical reaction diffusion between the metal substrate and the high-temperature oxide superconducting layer YBCO film, and at the same time, it can overcome the large lattice mismatch between the metal substrate and the superconducting layer to complete the texture transfer. Realize the necessary biaxial texture of the superconducting layer to achieve the excellent high current carrying capacity of the coated conductor in the strong magnetic field. The cost performance of coated conductors depends on the structure of the buffer layer and the preparation technology of the buffer layer. At present, high-performance coated conductors in the world usually use physical deposition techniques to prepare buffer layers, such as pulsed laser deposition, DC magnetron reactive sputtering, electron beam evaporation, etc. These techniques require expensive high-vacuum equipment, and the process requires The control factors are complicated, which increases the manufacturing cost of the coated conductor, which is not conducive to the large-scale application of the coated conductor. Non-vacuum chemical solution preparation techniques such as metal-organic deposition (MOD) or sol-gel (sol-gel) methods are effective methods to achieve low-cost and rapid preparation of coated conductor buffer layers. This technology can mix the precursors at the molecular level before film formation, so that the stoichiometric ratio can be precisely controlled, and it is easy to achieve large-scale preparation. Many research institutions in the world are developing non-vacuum chemical solution preparation technology for the buffer layer.

There are three crystal forms of pure zirconia: cubic phase (c-ZrO ₂ ), tetragonal phase (t-ZrO ₂ ), and monoclinic phase (m-ZrO ₂ ). Among them, the monoclinic phase is a low-temperature stable phase, and the cubic phase is a high-temperature stable phase. In the actual application process, it is necessary to consider the suppression of cracks caused by the volume change of zirconia due to the transformation of the crystal form, so it needs to be stabilized. After being doped with CaO, MgO, Y ₂ O ₃ and other oxides, the cubic phase can be stabilized at room temperature, avoiding the volume change caused by crystal transformation, and expanding its application. For example, YSZ (yttrium stabilized zirconia) has been widely used as a solid electrolyte material in solid oxide fuel cells and oxygen sensors. At the same time, YSZ is also a buffer layer material with relatively good thermal and chemical stability. Research institutes such as the United States and Japan use physical techniques such as magnetron sputtering to epitaxially CeO ₂ /YSZ/Y ₂ O ₃ buffer layer on the NiW alloy substrate. And CeO ₂ /YSZ/CeO ₂ buffer layer, where YSZ has good compatibility with the seed layer and the cap layer. When the chemical solution method is used to prepare the YSZ film, it often needs to exceed 1000°C to obtain a surface with good crystallinity, but this puts forward higher requirements for the thermal stability of the nickel-based alloy substrate texture.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a high-temperature superconducting coating conductor buffer layer to prepare cubic manganese-stabilized zirconia that can be epitaxially grown on different substrate interfaces and has a smooth surface. film.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a preparation method of a high-temperature superconducting coating conductor buffer layer, characterized in that the preparation process is:

(1) Preparation of precursor solution: Weigh zirconium acetylacetonate powder and manganese acetate tetrahydrate powder, prepare according to the atomic ratio of Mn:Zr=x:1-x, wherein 0.1≤x≤0.4, then add organic solvent propionic acid or methanol Dissolving at a low temperature of 80-120°C to obtain a precursor solution, the molar concentration of the precursor solution is 0.1M-0.5M;

(2) Spin coating or dip coating: select acetone-cleaned strontium titanate single wafer, or Ni-5at.%W alloy as substrate and coated with cubic textured La ₂ Zr ₂ O ₇ thin film substrate, During spin coating, the single wafer or substrate is placed horizontally on the suction port of the spin coater, and the precursor solution described in (1) is evenly dripped onto the single wafer or substrate, and the speed of the spin coater is 3000 revolutions/min. The coating time is 60s; during dip coating, the strontium titanate single wafer or the substrate is immersed in the precursor solution described in step (1) for 10s, then pulled out at 4cm/min, placed in an oven at 50-60°C, and obtained after 10min Precursor film;

(3) Crystallization treatment: Put the precursor film in step (2) into a high-temperature furnace. After cooling, a high-temperature superconducting coating conductor Mn _x Zr _1-x O ₂ buffer layer film is obtained, wherein 0.1≤x≤0.4.

The buffer layer technology prepared by the present invention can be verified by the following two substrates: SrTiO ₃ (100); Ni-5at.%W/La ₂ Zr ₂ O ₇ . After the precursor solution is deposited on the two substrates by spin coating or dip coating, the Mn-SZ buffer layer is obtained through the crystallization heat treatment of the above process, and the X-ray diffraction analysis shows that it has no random orientation and has a good cubic texture. This process can also deposit the precursor solution on single crystals such as YSZ to obtain a well-textured buffer layer.

Compared with the prior art, the present invention has the following advantages:

1. Mn-SZ (manganese stabilized zirconia) films capable of rapidly growing cubic texture. The process adopts the chemical solution method (CSD) to prepare the precursor solution, mixes it according to a certain stoichiometric ratio, and dissolves quickly in the organic acid or organic solvent when it is slightly heated, the preparation cycle is short, and the precursor can be evenly mixed at the molecular level; The precursor solution does not change in physical and chemical properties at room temperature, and the storage period is about one month.

2. The Mn-SZ (manganese stabilized zirconia) film prepared by this process has uniform chemical composition and fine grains, which greatly reduces the formation temperature of the cubic texture and is conducive to the growth of the biaxial texture of the superconducting layer.

3. The addition of Mn element improves the barrier performance of zirconia and effectively prevents the interdiffusion between the metal substrate and the superconducting layer.

The present invention will be described in further detail below with reference to the accompanying drawings and examples.

Description of drawings

Fig. 1 is the X-ray diffraction diagram of the Mn-SZ film with cubic texture epitaxially grown on strontium titanate SrTiO ₃ (100) in the present invention when Mn:Zr=0.25:7.25.

Fig. 2 is the X-ray diffraction pattern of the Mn-SZ film with cubic texture epitaxially grown on Ni-5at.%W/La ₂ Zr ₂ O ₇ in the present invention when Mn:Zr=0.25:7.25.

In the figure: NiW is the abbreviation of Ni-5at.%W, LZO is the abbreviation of La ₂ Zr ₂ O ₇ , and STO is the abbreviation of SrTiO ₃ (100).

Detailed ways

Example 1

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in propionic acid at an atomic ratio of Mn:Zr=0.1:0.90, and heated at a low temperature of 80-120°C to obtain a transparent solution. A 10×10×0.5mm SrTiO ₃ (100) single crystal substrate was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was washed away with deionized water and dried with nitrogen gas. The substrate is spin-coated or dip-coated with the above-mentioned transparent solution. During spin-coating, the substrate is placed horizontally on the suction port of the spin-coater, and the solution is evenly dripped onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s; for dip coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin coating or dip coating, put it in an oven at 50-60°C for 10 minutes and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 900°C at a rate of 3-4°C/min, kept for 5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

Example 2

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in propionic acid at an atomic ratio of Mn:Zr=0.1:0.90, and heated at a low temperature of 80-120°C to obtain a transparent solution. The substrate coated with the textured MOD-La ₂ Zr ₂ O ₇ film based on Ni-5at.% W was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was rinsed off with deionized water , blow dry with nitrogen. The substrate is spin-coated or dip-coated with the above-mentioned transparent solution. During spin-coating, the substrate is placed horizontally on the suction port of the spin-coater, and the solution is evenly dripped onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s; for dip coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin coating or dip coating, put it in an oven at 50-60°C for 10 minutes and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 1000°C at a rate of 3-4°C/min, held for 0.5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

Example 3

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in propionic acid at an atomic ratio of Mn:Zr=0.1:0.90, and heated at a low temperature of 80-120°C to obtain a transparent solution. A 10×10×0.5mm SrTiO ₃ (100) single crystal substrate was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was washed away with deionized water and dried with nitrogen gas. Use the above solution to spin-coat or dip-coat the substrate. When spin-coating, place the substrate horizontally on the suction port of the spin-coater, and drop the solution evenly onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s. ;Dip-coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin-coating or dip-coating, put it in an oven at 50-60°C for 10min and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 1000°C at a rate of 3-4°C/min, held for 0.5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

Example 4

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in an appropriate amount of propionic acid at an atomic ratio of Mn:Zr=0.25:0.75, and heated at a low temperature of 80-120°C to obtain a transparent solution. A 10×10×0.5mm SrTiO ₃ (100) single crystal substrate was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was washed away with deionized water and dried with nitrogen gas. The substrate is spin-coated or dip-coated with the above-mentioned transparent solution. During spin-coating, the substrate is placed horizontally on the suction port of the spin-coater, and the solution is evenly dripped onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s; for dip coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin coating or dip coating, put it in an oven at 50-60°C for 10 minutes and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 900°C at a rate of 3-4°C/min, kept for 5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

Example 5

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in an appropriate amount of propionic acid at an atomic ratio of Mn:Zr=0.25:0.75, and heated at a low temperature of 80-120°C to obtain a transparent solution. A 10×10×0.5mm SrTiO ₃ (100) single crystal substrate was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was washed away with deionized water and dried with nitrogen gas. The substrate is spin-coated or dip-coated with the above-mentioned transparent solution. During spin-coating, the substrate is placed horizontally on the suction port of the spin-coater, and the solution is evenly dripped onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s; for dip coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin coating or dip coating, put it in an oven at 50-60°C for 10 minutes and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 1000°C at a rate of 3-4°C/min, held for 0.5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

The buffer layer X-ray result of Fig. 1 shows that x=0.25 on SrTiO3 (100) (abbreviated as STO) can epitaxially grow the Mn-SZ film of cubic texture;

Example 6

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in an appropriate amount of propionic acid at an atomic ratio of Mn:Zr=0.25:0.75, and heated at a low temperature of 80-120°C to obtain a transparent solution. The substrate coated with the textured MOD-La ₂ Zr ₂ O ₇ film based on Ni-5at.% W was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was rinsed off with deionized water , blow dry with nitrogen. The substrate is spin-coated or dip-coated with the above-mentioned transparent solution. During spin-coating, the substrate is placed horizontally on the suction port of the spin-coater, and the solution is evenly dripped onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s; for dip coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin coating or dip coating, put it in an oven at 50-60°C for 10 minutes and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 900°C at a rate of 3-4°C/min, kept for 5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

Example 7

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in an appropriate amount of propionic acid at an atomic ratio of Mn:Zr=0.25:0.75, and heated at a low temperature of 80-120°C to obtain a transparent solution. The substrate coated with the textured MOD-La ₂ Zr ₂ O ₇ film based on Ni-5at.% W was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was rinsed off with deionized water , blow dry with nitrogen. The substrate is spin-coated or dip-coated with the above-mentioned transparent solution. During spin-coating, the substrate is placed horizontally on the suction port of the spin-coater, and the solution is evenly dripped onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s; for dip coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin coating or dip coating, put it in an oven at 50-60°C for 10 minutes and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 1000°C at a rate of 3-4°C/min, held for 0.5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

Example 8

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in an appropriate amount of propionic acid at an atomic ratio of Mn:Zr=0.25:0.75, and heated at a low temperature of 80-120°C to obtain a transparent solution. The substrate coated with the textured MOD-La ₂ Zr ₂ O ₇ film based on Ni-5at.% W was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was rinsed off with deionized water , blow dry with nitrogen. The substrate is spin-coated or dip-coated with the above-mentioned transparent solution. During spin-coating, the substrate is placed horizontally on the suction port of the spin-coater, and the solution is evenly dripped onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s; for dip coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin coating or dip coating, put it in an oven at 50-60°C for 10 minutes and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 1000°C at a rate of 3-4°C/min, kept for 5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

The X-ray results of the buffer layer in Figure 2 show that when x=0.25, a Mn-SZ film with a cubic texture can be epitaxially grown on Ni-5at.%W/La ₂ Zr ₂ O ₇ ;

Example 9

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in an appropriate amount of propionic acid at an atomic ratio of Mn:Zr=0.4:0.60, and heated at a low temperature of 80-120°C to obtain a transparent solution. A 10×10×0.5mm SrTiO ₃ (100) single crystal substrate was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was washed away with deionized water and dried with nitrogen gas. The substrate is spin-coated or dip-coated with the above-mentioned transparent solution. During spin-coating, the substrate is placed horizontally on the suction port of the spin-coater, and the solution is evenly dripped onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s; for dip coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin coating or dip coating, put it in an oven at 50-60°C for 10 minutes and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 1000°C at a rate of 3-4°C/min, kept for 5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

Example 10

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in an appropriate amount of propionic acid at an atomic ratio of Mn:Zr=0.4:0.60, and heated at a low temperature of 80-120°C to obtain a transparent solution. The substrate coated with the textured MOD-La ₂ Zr ₂ O ₇ film based on Ni-5at.% W was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was rinsed off with deionized water , blow dry with nitrogen. The substrate is spin-coated or dip-coated with the above-mentioned transparent solution. During spin-coating, the substrate is placed horizontally on the suction port of the spin-coater, and the solution is evenly dripped onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s; for dip coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin coating or dip coating, put it in an oven at 50-60°C for 10 minutes and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 1000°C at a rate of 3-4°C/min, held for 0.5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

Example 11

Two organic reagents, zirconium acetylacetonate and manganese acetate tetrahydrate, are dissolved in an appropriate amount of propionic acid at an atomic ratio of Mn:Zr=0.4:0.60, and heated at a low temperature of 80-120°C to obtain a transparent solution. The substrate coated with the textured MOD-La ₂ Zr ₂ O ₇ film based on Ni-5at.% W was chosen to be ultrasonically cleaned in acetone to remove surface oil, and then the acetone solvent was rinsed off with deionized water , blow dry with nitrogen. The substrate is spin-coated or dip-coated with the above-mentioned transparent solution. During spin-coating, the substrate is placed horizontally on the suction port of the spin-coater, and the solution is evenly dripped onto the substrate. The speed of the spin-coater is 3000 rpm, and the spin-coating time is 60s; for dip coating, the substrate is immersed in the solution for 10s, and then pulled out at 4cm/min. After spin coating or dip coating, put it in an oven at 50-60°C for 10 minutes and take it out. The substrate is taken out and placed in a high-temperature furnace, raised to 1000°C at a rate of 3-4°C/min, kept for 5 hours, and cooled with the furnace to obtain the Mn-SZ cubic texture buffer layer film of this preparation process.

The research results of the present invention show that manganese doping can refine zirconia grains compared with Y doping, which indirectly reduces the crystallization temperature of the cubic phase, thereby avoiding the baseband texture of nickel-based alloys caused by high-temperature treatment The change. Manganese can enter the ZrO ₂ lattice to partially replace Zr ⁴⁺ ions through high-temperature treatment, forming a displacement solid solution, thereby obtaining a low eutectic Mn-SZ (manganese-stabilized zirconia), so that the cubic phase zirconia can be retained from high temperature to room temperature . The present invention adopts the chemical solution method to replace yttrium with manganese as a stabilizer based on zirconia, and it is confirmed by experiments that the prepared Mn-SZ film can epitaxially grow a sharp cubic texture on a single crystal and other buffer layers, and the epitaxial film has With good surface crystallinity, it is an ideal buffer layer material for preparing coated conductors by chemical solution method.

Claims (1)

1. A preparation method for a high-temperature superconducting coating conductor buffer layer, characterized in that the preparation process is: (1) Preparation of precursor solution: Weigh zirconium acetylacetonate powder and manganese acetate tetrahydrate powder, prepare according to the atomic ratio of Mn:Zr=x:1-x, wherein 0.1≤x≤0.4, then add organic solvent propionic acid or methanol Dissolving at a low temperature of 80-120°C to obtain a precursor solution, the molar concentration of the precursor solution is 0.1M-0.5M; (2) Spin coating or dip coating: select acetone-cleaned strontium titanate single wafer, or Ni-5at.%W alloy as substrate and coated with cubic textured La ₂ Zr ₂ O ₇ thin film substrate, During spin coating, the single wafer or substrate is placed horizontally on the suction port of the spin coater, and the precursor solution described in (1) is evenly dripped onto the single wafer or substrate, and the speed of the spin coater is 3000 revolutions/min. The coating time is 60s; during dip coating, the strontium titanate single wafer or the substrate is immersed in the precursor solution described in step (1) for 10s, then pulled out at 4cm/min, placed in an oven at 50-60°C, and obtained after 10min Precursor film; (3) Crystallization treatment: Put the precursor film in step (2) into a high-temperature furnace. After cooling, a high-temperature superconducting coating conductor Mn _x Zr _1-x O ₂ buffer layer film is obtained, wherein 0.1≤x≤0.4.

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