CN102222761A - Preparation method of high temperature superconductive coating conductor La2Zr2O7 buffer layer film - Google Patents

Abstract

The invention discloses a preparation method of high temperature superconductive coating conductor La2Zr2O7 buffer layer film. The method comprises the following steps: dissolving lanthanum nitrate (La(NO3)3 6H2O) and zirconium nitrate (Zr(NO3)4 5H2O) into ethylene glycol monobutyl ether to form anhydrous solution; adding polyethylene glycol PEG-2000 into the anhydrous solution to form colloid with good film forming ability; coating the colloid on a substrate, drying it, then putting it in a sintering furnace to sinter and obtain a La2Zr2O7 high temperature superconductive coating conductor buffer layer. The method in the invention has low production cost. By using the method, high quality La2Zr2O7 film is easily prepared, which plays the role of coating conductor buffer layer effectively.

Description

A kind of preparation conductor of high-temperature superconductor coat La 2Zr 2O 7The method of buffer layer thin film

Technical field

The invention belongs to the high temperature superconducting materia preparing technical field, relate in particular to the technology of preparing of buffer layers of high-temperature superconducting coating conductors film.

Background technology

Second generation belt material of high temperature superconduct is a RE, Ba and Cu oxide ReBCO coating conductor, because its good intrinsic electromagnetic property, especially its current capacity good under the highfield, gathers around in electric power system and has broad application prospects.

The composition of the high-temperature superconductor layer of coating conductor is ReBa ₂Cu ₃O _x(be called for short ReBCO, Re is yttrium or lanthanide series).For practical application area such as superconducting wire, superconducting magnets, the ReBCO high-temperature oxide superconducting material of fragility must be coated in could reduce on the good metal substrate of mechanical performance (intensity, toughness) avoid processing or use in mechanical damage.In addition, this backing material also need have good electrical conductivity and thermal conductivity, to avoid in the use because thrashing and collapse that local quench causes.

ReBCO high-temperature superconductor layer material is because the layer structure of itself causes extremely strong anisotropy, and the load current ability on the ab face of lattice is higher than the c direction of principal axis far away.The current-carrying performance of ReBCO high temperature superconducting materia is very responsive to the lattice mismatch on a, the b direction, and big lattice mismatch angle will form weak connection, has a strong impact on its current capacity.Studies show that the current capacity of ReBCO is exponential damping with the increase at lattice mismatch angle on a, the b direction.Reduce lattice mismatch angle on a, the b direction, reduce weak joint efficiency, guarantee the current capacity of ReBCO, extension has been configured to indispensable technical process in its technology of preparing.Up to now, the best backing material of generally acknowledging both at home and abroad is the Ni base alloy material.And there is certain lattice mismatch in the ab face of Ni base alloy and ReBCO high temperature superconducting materia, and directly epitaxial growth ReBCO high temperature superconducting materia almost is impossible on the Ni base alloy baseband.Moreover, in the one-tenth phase heat treatment process of ReBCO, having stronger counterdiffusion mutually and chemical reaction between Ni base alloy and the ReBCO, this has just had a strong impact on the superconductivity of ReBCO.Therefore, between Ni base alloy substrate and ReBCO, must increase one deck cushioning layer material, should serve as from Ni base alloy to the epitaxially grown intermediate die plate of ReBCO, stop the phase counterdiffusion of two kinds of materials again, mainly be Ni with ReBCO in the counterdiffusion mutually of Cu, could guarantee to prepare the ReBCO conductor of high-temperature superconductor coat of function admirable like this.Therefore, conductor of high-temperature superconductor coat all has substrate, resilient coating (one deck at least) and ReBCO superconducting coating three-decker.

In recent years, La ₂Zr ₂O ₇As the resilient coating of coating conductor since its good thermal stability and with Ni base alloy and the good chemical matching of YBCO, become the focus of coating conductor research.And relevant chemical solution method prepares La ₂Zr ₂O ₇The report of resilient coating is a lot.People such as Chirayil have at first carried out La ₂Zr ₂O ₇Chemical preparation, on the NiW base band, utilize the normal propyl alcohol salt of the isopropoxide of lanthanum and zirconium to prepare the La of biaxial texture ₂Zr ₂O ₇Resilient coating.People such as Sathyamurthy have carried out deep research, have developed La ₂Zr ₂O ₇The technology of preparing of long band.People such as S Engel are that predecessor has made La with the pentanediol salt of lanthanum and zirconium ₂Zr ₂O ₇Film.Respectively referring to document 1, T.G.Chirayil, M.Paranthaman, D.B.Beach, D.F.Lee, A.Goyal, R.K.Williams, X.Cui, D.M.Kroeger, R.Feenstra, D.T.Verebelyi and D.K.Christen.Epitaxial growth of La2Zr2O7 thin films on rolled Ni-substrates by sol-gel process for high Tc superconducting tapes.Physica C.2000,336:63; Document 2, S.Sathyamurthy, M.Paranthaman and H.Y.Zhai.Lanthanum zirconate:a single buffer layer processed by solution deposition for coated conductor fabrication.J.Mater.Res.2002,17:2181; Document 3, S.Engel, K.Knoth, R.Huhne, L.Schultz and B.Holzapfel.An all chemical solution deposition approach for the growth of highly textured CeO ₂Cap layers on La ₂Zr ₂O ₇-buffered long lengths of biaxiallytextured Ni W substrates for YBCO-coated conductors.Supercond.Sci.Technol.2005,18:1385.

But the common ground of above method is all to have adopted metal alkoxide or acetylacetonate as predecessor.Because metal alkoxide or acetylacetonate cost an arm and a leg, this will limit the development of practicability band.

Summary of the invention

The object of the present invention is to provide a kind of preparation conductor of high-temperature superconductor coat La ₂Zr ₂O ₇The method of buffer layer thin film.The cost of manufacture of this method is low, easily makes high-quality La ₂Zr ₂O ₇Film can be brought into play the effect of coating conductor buffer layer effectively.

The present invention realizes that the technical scheme that its goal of the invention adopts is, a kind of preparation conductor of high-temperature superconductor coat La ₂Zr ₂O ₇The method of buffer layer thin film the steps include:

A, anhydrous solution preparation: with lanthanum nitrate (La (NO ₃) ₃6H ₂O) and zirconium nitrate (Zr (NO ₃) ₄5H ₂O) ratio that equals 1: 1 in the amount of ions ratio of lanthanum, zirconium is dissolved in the EGME, forms anhydrous solution;

B, colloid for preparing: in a anhydrous solution in step, add polyethylene glycol-20000 and form colloid;

C, colloid coating are with dry: the colloid that the b step is made is coated on the substrate, carries out drying again;

D, thermal decomposition process: the substrate that will be coated with colloid places sintering furnace, and to feed the H2 volume content in whole thermal decomposition process process be 5% H ₂-Ar gaseous mixture,, make furnace temperature rise to 340 ℃-420 ℃ with the speed of 0.7 ℃/min from room temperature, the speed with 1.0-1.4 ℃/min rises to 570 ℃-600 ℃ again, is incubated 0.5-1 hour again, allows stove be cooled to room temperature naturally then.

E, sinter phase into: the substrate after the thermal decomposition process is put into sintering furnace, and feeding H2 volume content is 5% H in the sintering furnace earlier ₂-Ar gaseous mixture rises to 970 ℃-1000 ℃ with furnace temperature with the speed of 25-100 ℃/min again, is incubated 0.5-1 hour, allows stove be cooled to room temperature naturally then, promptly.

Compared with prior art, the invention has the beneficial effects as follows:

One, before the sintering, carry out predecomposition by selected programming rate and temperature range and handle, the coating that can make sintering form is more smooth, finer and close.Sinter phase time into, earlier feeding H2 volume content is 5% H2-Ar gaseous mixture in the sintering furnace.Can guarantee that like this lanthanum zirconium oxygen can form good biaxial texture.

Two, the initiation material of preparation process use is cheap metal nitrate, has reduced cost of manufacture; The film forming macromolecular compound that adds is cheap, uses extensive, nontoxic polyethylene glycol-20000, and its addition is also few, has further reduced cost of manufacture; Only need the gained colloid is coated on the substrate sintering and gets final product, manufacture craft is simple, and operation control easily.

Above-mentioned polyethylene glycol-20000 addition is the 3%-5% that accounts for the colloid gross mass.Such ratio can guarantee the colloid good film-forming property made.

Above-mentioned substrate is the LaAlO of biaxial texture ₃Monocrystal chip

The on-chip concrete practice that above-mentioned c in the step is coated in colloid coating conductor is: on substrate, use the sol evenning machine spin coated again on substrate colloid drops.

Above-mentioned c in the step temperature when dry be 100 ℃ of-200 ℃ of dryings.

Under this temperature conditions, can so that the EGME in the colloid can be more, vapor away quickly.

The present invention is described in further detail below in conjunction with the drawings and specific embodiments.

Description of drawings

Fig. 1 is the La that embodiment one makes ₂Zr ₂O ₇The X ray diffracting spectrum of resilient coating.

Fig. 2 is the La that embodiment one makes ₂Zr ₂O ₇10000 times of scanning electron microscopy (SEM) photo of resilient coating.

Fig. 3 is the La that embodiment two makes ₂Zr ₂O ₇The X ray diffracting spectrum of resilient coating.

Fig. 4 is the La that embodiment two makes ₂Zr ₂O ₇10000 times of scanning electron microscopy (SEM) photo of resilient coating.

Fig. 5 is the La that embodiment three makes ₂Zr ₂O ₇The X ray diffracting spectrum of resilient coating.

Fig. 6 is the La that embodiment three makes ₂Zr ₂O ₇10000 times of scanning electron microscopy (SEM) photo of resilient coating.

Fig. 1,3,5 ordinate are diffracted intensity (Intensity), arbitrary unit (a.u.); Abscissa is the angle of diffraction 2 θ, and unit is degree (deg), and character LZO is La among the figure ₂Zr ₂O ₇Write a Chinese character in simplified form

Embodiment

Embodiment one

First kind of embodiment of the present invention is a kind of preparation conductor of high-temperature superconductor coat La ₂Zr ₂O ₇The method of buffer layer thin film the steps include:

A, anhydrous solution preparation: with lanthanum nitrate (La (NO ₃) ₃6H ₂O) and zirconium nitrate (Zr (NO ₃) ₄5H ₂O) ratio that equals 1: 1 in the amount of ions ratio of lanthanum, zirconium is dissolved in the EGME, and the ultrasonic solution that makes is even, forms anhydrous solution;

B, colloid for preparing: (polyethylene glycol, PEG-20000) ultrasonic dissolution form colloid to add polyethylene glycol-20000 in a anhydrous solution in step.The addition of polyethylene glycol-20000 accounts for 5% of colloid gross mass.

C, colloid coating are with dry: the colloid that the b step is made is coated on the substrate, and is dry down at 150 ℃ again.The on-chip concrete practice that colloid is coated in coating conductor is: on substrate, with the sol evenning machine rotation, colloid evenly is coated on the substrate colloid drops.

D, thermal decomposition process: the substrate that will be coated with colloid places sintering furnace, and feed to feed the H2 volume content in sintering furnace be 5% H2-Ar gaseous mixture, make furnace temperature rise to 340 ℃ with the speed of 0.7 ℃/min, speed with 1.0 ℃/min rises to 600 ℃ again, be incubated 0.5 hour, allow stove be cooled to room temperature naturally then.

E, sinter phase into: the substrate after the thermal decomposition process is put into sintering furnace, earlier feeding H2 volume content is 5% H2-Ar gaseous mixture in the sintering furnace, again furnace temperature is risen to 970 ℃ fast with the speed of 25 ℃/min, be incubated 1 hour, allow stove be cooled to room temperature naturally then, obtain lanthanum zirconium oxygen (La ₂Zr ₂O ₇) buffer layers of high-temperature superconducting coating conductors.

Fig. 1 is the La of the embodiment of the invention one ₂Zr ₂O ₇The X ray diffracting spectrum of resilient coating.It locates all to exist diffraction maximum, i.e. a La at 33.197 ° and 69.686 ° ₂Zr ₂O ₇(400) and La ₂Zr ₂O ₇(800), and do not have other assorted peaks, show La ₂Zr ₂O ₇There is the outer texture of very strong face in buffer layer thin film.

Fig. 2 is the embodiment of the invention one La ₂Zr ₂O ₇10000 times of scanning electron microscopy (SEM) photo of resilient coating.As shown in Figure 2: film sample surfacing, densification, no hole is seamless.Hence one can see that, and that this embodiment one prepared texture is good, the La that surface compact is smooth ₂Zr ₂O ₇Buffer layer thin film.

Embodiment two

This routine preparation method is made of following steps successively:

A, anhydrous solution preparation: with lanthanum nitrate (La (NO ₃) ₃6H ₂O) and zirconium nitrate (Zr (NO ₃) ₄5H ₂O) ratio that equals 1: 1 in the amount of ions ratio of lanthanum, zirconium is dissolved in the EGME, and the ultrasonic solution that makes is even, forms anhydrous solution;

B, colloid for preparing: (polyethylene glycol, PEG-20000) ultrasonic dissolution form colloid to add polyethylene glycol-20000 in a anhydrous solution in step.The addition of polyethylene glycol-20000 accounts for 4% of colloid gross mass.

C, colloid coating are with dry: the colloid that the b step is made is coated on the substrate, and is dry down at 100 ℃ again.The on-chip concrete practice that colloid is coated in coating conductor is: on substrate, with the sol evenning machine rotation, colloid evenly is coated on the substrate colloid drops.

D, thermal decomposition process: the substrate that will be coated with colloid places sintering furnace, and feed to feed the H2 volume content in sintering furnace be 5% H2-Ar gaseous mixture, make furnace temperature rise to 400 ℃ with the speed of 0.7 ℃/min, speed with 1.2 ℃/min rises to 570 ℃ again, be incubated 1 hour, allow stove be cooled to room temperature naturally then.

E, sinter phase into: the substrate after the thermal decomposition process is put into sintering furnace, earlier feeding H2 volume content is 5% H2-Ar gaseous mixture in the sintering furnace, again furnace temperature is risen to 990 ℃ fast with the speed of 40 ℃/min, be incubated 0.5 hour, allow stove be cooled to room temperature naturally then, obtain lanthanum zirconium oxygen (La ₂Zr ₂O ₇) buffer layers of high-temperature superconducting coating conductors.

Fig. 3 is the La of the embodiment of the invention two ₂Zr ₂O ₇The X ray diffracting spectrum of resilient coating.It locates all to exist diffraction maximum, i.e. a La at 33.197 ° and 69.686 ° ₂Zr ₂O ₇(400) and La ₂Zr ₂O ₇(800), and do not have other assorted peaks, show La ₂Zr ₂O ₇There is the outer texture of very strong face in buffer layer thin film.

Fig. 4 is the embodiment of the invention one La ₂Zr ₂O ₇10000 times of scanning electron microscopy (SEM) photo of resilient coating.As shown in Figure 4: film sample surfacing, densification, no hole is seamless.Hence one can see that, and that this embodiment one prepared texture is good, the La that surface compact is smooth ₂Zr ₂O ₇Buffer layer thin film.

Embodiment three

This routine preparation method is made of following steps successively:

A, anhydrous solution preparation: with lanthanum nitrate (La (NO ₃) ₃6H ₂O) and zirconium nitrate (Zr (NO ₃) ₄5H ₂O) ratio that equals 1: 1 in the amount of ions ratio of lanthanum, zirconium is dissolved in the EGME, and the ultrasonic solution that makes is even, forms anhydrous solution;

B, colloid for preparing: (polyethylene glycol, PEG-20000) ultrasonic dissolution form colloid to add polyethylene glycol-20000 in a anhydrous solution in step.(polyethylene glycol, addition PEG-20000) accounts for 3% of colloid gross mass to polyethylene glycol-20000.

C, colloid coating are with dry: the colloid that the b step is made is coated on the substrate, and is dry down at 200 ℃ again.

D, thermal decomposition process: the substrate that will be coated with colloid places sintering furnace, and feed to feed the H2 volume content in sintering furnace be 5% H2-Ar gaseous mixture, make furnace temperature rise to 420 ℃ with the speed of 0.7 ℃/min, speed with 1.4 ℃/min rises to 580 ℃ again, be incubated 0.7 hour, allow stove be cooled to room temperature naturally then.

E, sinter phase into: the substrate after the thermal decomposition process is put into sintering furnace, earlier feeding H2 volume content is 5% H2-Ar gaseous mixture in the sintering furnace, again furnace temperature is risen to 1000 ℃ fast with the speed of 100 ℃/min, be incubated 40 minutes, allow stove be cooled to room temperature naturally then, obtain lanthanum zirconium oxygen (La2Zr2O7) buffer layers of high-temperature superconducting coating conductors.

Fig. 5 is the La of the embodiment of the invention three ₂Zr ₂O ₇The X ray diffracting spectrum of resilient coating.It locates all to exist diffraction maximum, i.e. a La at 33.197 ° and 69.686 ° ₂Zr ₂O ₇(400) and La ₂Zr ₂O ₇(800), and do not have other assorted peaks, show La ₂Zr ₂O ₇There is the outer texture of very strong face in buffer layer thin film.

Fig. 6 is the embodiment of the invention three La ₂Zr ₂O ₇10000 times of scanning electron microscopy (SEM) photo of resilient coating.As shown in Figure 6: film sample surfacing, densification, no hole is seamless.Hence one can see that, and that this embodiment one prepared texture is good, the La that surface compact is smooth ₂Zr ₂O ₇Buffer layer thin film.

Its purity of the EGME that uses in the preparation process of La2Zr2O7 coating conductor buffer layer of the present invention reaches more than 99.5% and gets final product, and also promptly uses chemical pure EGME to get final product.When adding lanthanum nitrate and zirconium nitrate in EGME, addition can fully be dissolved with admixture and be got final product; When the admixture total amount was 1 mole usually, the volume of EGME was the 0.5-3 liter.In the whole sintering process, feed 5% H2-Ar gaseous mixture in the sintering furnace, the hydrogen in the gaseous mixture and the purity of argon gas are preferably 99.99%, and the performance of manufactured goods can be guaranteed; Otherwise the performance of manufactured goods will reduce.

Claims (4)

1. one kind prepares conductor of high-temperature superconductor coat La ₂Zr ₂O ₇The method of buffer layer thin film the steps include:

A, anhydrous solution preparation: with lanthanum nitrate (La (NO ₃) ₃6H ₂O) and zirconium nitrate (Zr (NO ₃) ₄5H ₂O) ratio that equals 1: 1 in the amount of ions ratio of lanthanum, zirconium is dissolved in the EGME, forms anhydrous solution;

B, colloid for preparing: in a anhydrous solution in step, add polyethylene glycol-20000 and form colloid;

C, colloid coating are with dry: the colloid that the b step is made is coated on the substrate, carries out drying again;

D, thermal decomposition process: the substrate that will be coated with colloid places sintering furnace, and to feed the H2 volume content in whole thermal decomposition process process be 5% H2-Ar gaseous mixture, make furnace temperature rise to 340 ℃-420 ℃ with the speed of 0.7 ℃/min from room temperature, speed with 1.0-1.4 ℃/min rises to 570 ℃-600 ℃ again, be incubated 0.5-1 hour again, allow stove be cooled to room temperature naturally then.

E, sinter phase into: the substrate after the thermal decomposition process is put into sintering furnace, earlier feeding H2 volume content is 5% H2-Ar gaseous mixture in the sintering furnace, again furnace temperature is risen to 970 ℃-1000 ℃ with the speed of 25-100 ℃/min, is incubated 0.5-1 hour, allow stove be cooled to room temperature naturally then, promptly.

2. preparation conductor of high-temperature superconductor coat La as claimed in claim 1 ₂Zr ₂O ₇The method of buffer layer thin film is characterized in that: the addition of the polyethylene glycol-20000 of described b in the step is the 3%-5% of colloid gross mass.

3. preparation conductor of high-temperature superconductor coat La as claimed in claim 1 ₂Zr ₂O ₇The method of buffer layer thin film is characterized in that: the on-chip concrete practice that described c in the step is coated in colloid coating conductor is: on substrate, with the sol evenning machine rotation, colloid evenly is coated on the substrate colloid drops.

4. conductor of high-temperature superconductor coat La as claimed in claim 1 ₂Zr ₂O ₇The method of buffer layer thin film is characterized in that: described c in the step temperature when dry be 100 ℃-200 ℃.