Process for the production of highly-textured, band-shaped, high-temperature superconductors
The formation of band-shaped HTSL on a metal substrate is disclosed. The HTSL includes at least one buffer layer comprising zirconates and/or rare-earth oxides. The HTSL layer is formed on the buffer layer. The buffer layer has a texturing that in the case of a RHEED measurement results in discrete reflexes and not only in diffraction rings. In particular, the buffer layer may be textured along its interface with the HTSL layer.
1. A method of producing band-shaped HTSL including a metal substrate, at least one buffer layer, and an HTSL that is located on the buffer layer, the method comprising:
(a) providing a coating solution comprising a polar solvent with at least one free hydroxyl group;
(b) applying the coating solution to the metal substrate;
(c) drying the coating;
(d) applying an annealing treatment to the coating to produce the buffer layer; and
(e) applying the HTSL layer to the buffer layer
wherein the polar solvent with at least one free hydroxyl group comprises propionic acid.
2. The method according to claim 1 , wherein the coating solution further comprises one or more of a zirconium compound, a lanthanum compound, and a rare earth compound.
3. The method according to claim 2 , wherein:
the zirconium compound comprises zirconium(IV) 2,4-pentadionate;
the lanthanum compound comprises lanthanum(III) 2,4-pentadionate; and
the rare earth compound is selected from the group consisting of cerium(III) acetylacetonate, Gd(III) acetylacetonate, and yttrium(III) 2,4-pentadionate.
4. The method according to claim 1 , wherein the coating solution further comprises lanthanum(III) 2,4-pentadionate and zirconium(II) 2,4-pentadionate dissolved in propionic acid.
5. The method according to claim 4 , wherein the coating solution has a concentration in the range of 0.04 M to 0.5 M relative to La 2 Zr 2 O 7 .
6. The method according to claim 1 , wherein step (d) comprises applying the annealing treatment at temperatures of approximately 800°-900° C.
7. The method according to claim 1 , wherein step (b) comprises (b.1) receiving the substrate into a dipping apparatus including a dipping basin, wherein the substrate is pulled from the dipping basin at a rate of between about 0.05 cm/s and about 0.5 cm/s.
8. The method according to claim 1 , wherein step (b) comprises (b.1) receiving the substrate into a continuous coating apparatus, wherein the substrate is pulled out under a pull-out angle of between about 20° to 90° at a drawing speed of between about 0.05 cm/s and about 0.15 cm/s.
9. The method according to claim 1 , wherein the coating solution comprises yttrium(III) 2,4-pentadionate dissolved in a mixture comprising 24%-100% propionic acid and at least one of methoxyl alcohol, acetyl acetone, methanol, isobutylamine.
10. The method according to claim 9 , wherein step (d) comprises annealing the coating at a temperature of about 1000° C.
11. The method according to claim 1 , wherein the coating solution further comprises a wetting agent.
12. The method according to claim 1 , wherein (d) comprises (d.1) applying an annealing treatment to the coating to form a buffer layer comprising cerium oxide.
13. The method according to claim 12 , wherein forming the buffer layer comprising cerium oxide produces gadolinium-doped cerium oxide.
14. A method of forming a band-shaped HTSL including a metal substrate, two buffer layers comprising La 2 Zr 2 O 7 , a buffer layer comprising gadolinium-doped cerium oxide, and at least one HTSL layer, the method comprising:
(a) producing a first coating solution comprising lanthanum(III) 2,4-pentadionate and zirconium(IV) 2,4-pentadionate dissolved in propionic acid;
(b) applying the first coating solution to the metal substrate;
(c) drying the coating;
(d) applying a first annealing treatment to form a first La 2 Zr 2 O 7 buffer layer;
(e) applying the first coating solution to the first buffer layer and drying the coating;
(f) applying a second annealing treatment to form a second La 2 Zr 2 O 7 buffer layer;
(g) producing a second coating solution comprising:
cerium(III) acetylacetonate in 2-methoxylethanol, and
gadolinium(III) acetylacetonate in propionic acid;
(h) applying the second coating solution on the second La 2 Zr 2 O 7 buffer layer and drying the second coating;
(i) applying a third annealing treatment to form a third buffer layer comprising gadolinium-doped cerium oxide; and
(j) applying the HTSL layer to the third buffer layer,
wherein the concentration of the second coating solution is 0.1 M to 0.4 M, relative to the overall metal content of CeO 2 /Gd 2 O 3 .
15. A method of forming band-shaped HTSL including a metal substrate, two buffer layers comprising La 2 Zr 2 O 7 , a buffer layer comprising cerium oxide, and at least one HTSL layer, the method comprising:
(a) forming a first coating solution comprising lanthanum(III) 2,4-pentadionate and zirconium(IV) 2,4-pentadionate dissolved in propionic acid;
(b) applying the first coating solution to the metal substrate and drying the coating;
(c) applying an annealing treatment to form a first La 2 Zr 2 O 7 buffer layer;
(d) applying the first coating solution to the first La 2 Zr 2 O 7 buffer layer and drying the coating;
(e) applying a second annealing treatment to form a second La 2 Zr 2 O 7 buffer layer;
(f) forming a second coating solution comprising:
cerium(III) acetate dissolved in propionic acid,
2-propanol, and
acetyl acetone;
(g) applying the second coating solution to the second La 2 Zr 2 O 7 buffer layer and drying the coating;
(h) applying a third annealing treatment to form a third buffer layer comprising cerium oxide; and
(g) applying an HTSL layer on the third buffer layer.
16. The method according to claim 15 , wherein the second coating solution comprises at least 50% propionic acid.
17. The method according to claim 16 , wherein the ratio of propionic acid:2-propanol:acetyl acetone is about 5:2:1.
18. The method according to one of claim 1 , wherein the metal substrate is textured.
19. The method according to one of claim 1 , wherein the metal substrate comprises pure nickel.
20. The method according to claim 1 , wherein step (c) comprises:
drying the coating solution at a first temperature below the boiling point of the polar solvent; and
drying the coating at a second temperature above the boiling point of the polar solvent.
21. The method according to claim 1 , further comprising (f) heating the coating solution before applying the solution to the substrate.
22. The method according to claim 1 , wherein the coating solution further comprises a gelling agent.