Composition for thick oxide superconductor film and method of producing oxide superconductor in form of thick film tape using the same
View Patent ↗To provide a composition for a thick oxide superconducting film containing a copper salt of a branched saturated aliphatic carboxylic acid having 6 or more carbon atoms and/or a copper salt of an alicyclic carboxylic acid having 6 or more carbon atoms, which is suitable for producing thick copper based oxide superconducting films by the MOD process and which can be subjected to film formation with uniformity at a high speed, and an oxide superconductor in the form of a thick film tape which is subjected to film formation with uniformity at a high speed using the subject composition for a thick oxide superconducting film.
1. A composition for a thick oxide superconducting film, containing a copper salt of a branched saturated aliphatic carboxylic acid having 6 or more carbon atoms or a copper salt of an alicyclic carboxylic acid having 6 or more carbon atoms, and further containing yttrium trifluoroacetate and barium trifluoroacetate.
2. The composition for a thick oxide superconducting film according to claim 1 , wherein the copper salt of a branched saturated aliphatic carboxylic acid having 6 or more carbon atoms or the copper salt of an alicyclic carboxylic acid having 6 or more carbon atoms is at least one kind selected from the group consisting of copper neodecanoate, copper isononanoate, copper 2-ethylhexanoate, and copper naphthenate.
3. The composition for a thick oxide superconducting film according to claim 2 , containing an organic solvent having a boiling point of 80° C. or higher as a solvent.
4. The composition for a thick oxide superconducting film according to claim 3 , which is characterized in that the foregoing organic solvent is 2-octanone.
5. A composition for a thick oxide superconducting film, containing a copper salt of a branched saturated aliphatic carboxylic acid having 6 or more carbon atoms or a copper salt of an alicyclic carboxylic acid having 6 or more carbon atoms, and containing an yttrium salt of a branched saturated aliphatic carboxylic acid having 6 or more carbon atoms or an yttrium salt of an alicyclic carboxylic acid having 6 or more carbon atoms, and further containing barium trifluoroacetate.
6. The composition for a thick oxide superconducting film according to claim 5 , wherein the copper salt of a branched saturated aliphatic carboxylic acid having 6 or more carbon atoms or the copper salt of an alicyclic carboxylic acid having 6 or more carbon atoms is at least one kind selected from the group consisting of copper neodecanoate, copper isononanoate, copper 2-ethylhexanoate, and copper naphthenate.
7. The composition for a thick oxide superconducting film according to claim 6 , containing an organic solvent having a boiling point of 80° C. or higher as a solvent.
8. The composition for a thick oxide superconducting film according to claim 7 , which is characterized in that the foregoing organic solvent is 2-octanone.
9. A method of producing an oxide superconductor in the form of a thick film tape comprising the steps of:
coating a composition for a thick oxide superconducting film, containing a copper salt of a branched saturated aliphatic carboxylic acid having 6 or more carbon atoms or a copper salt of an alicyclic carboxylic acid having 6 or more carbon atoms, and further containing yttrium trifluoroacetate and barium trifluoroacetate, on a substrate,
subjecting an oxide superconducting precursor, which is obtained by a heat treatment for calcination, to a heat treatment for crystallization, and
forming a thick oxide superconductor film on said substrate.
10. The method of producing the oxide superconductor in the form of a thick film tape according to claim 9 , wherein in said heat treatment for calcination, a heating rate is 20° C./min or more.
11. The method of producing the oxide superconductor in the form of a thick film tape according to claim 9 , wherein in said heat treatment for calcination, the product of the traveling speed of the substrate and the temperature gradient is preferably 20° C./min or more.
12. The method of producing the oxide superconductor in the form of a thick film tape according to claim 9 , wherein said heat treatment for calcination is carried out at 250° C. or higher in the atmosphere having a water vapor partial pressure of not more than 2.1% by volume.
13. The method of producing the oxide superconductor in the form of a thick film tape according to claim 9 , wherein a difference between the maximum thickness portion and the minimum thickness portion in said thick oxide superconducting film is 1 μm or less.
14. The method of producing the oxide superconductor in the form of a thick film tape according to claim 9 , wherein the amount of change in critical current density is ±0.5 MA/cm 2 .
15. The method of producing the oxide superconductor in the form of a thick film tape according to claim 9 , wherein said thick oxide superconducting film is comprised of RE 1+x Ba 2−x Cu 3 O y (wherein RE represents at least one element selected from the group consisting of Y, Nd, Sm, Gd, Eu, Yb, Pr and Ho; x represents the number of 0≦x≦0.4; and y represents the number of 6.5≦y≦7.0).
16. A method of producing an oxide superconductor in the form of a thick film tape comprising the steps of:
coating a composition for a thick oxide superconducting film, containing a copper salt of a branched saturated aliphatic carboxylic acid having 6 or more carbon atoms or a copper salt of an alicyclic carboxylic acid having 6 or more carbon atoms, and containing an yttrium salt of a branched saturated aliphatic carboxylic acid having 6 or more carbon atoms or an yttrium salt of an alicyclic carboxylic acid having 6 or more carbon atoms, and further containing barium trifluoroacetate, on a substrate,
subjecting an oxide superconducting precursor, which is obtained by a heat treatment for calcination, to a heat treatment for crystallization, and
forming a thick oxide superconductor film on said substrate.
17. The method of producing the oxide superconductor in the form of a thick film tape according to claim 16 , wherein in said heat treatment for calcination, a heating rate is 2° C./min or more.
18. The method of producing the oxide superconductor in the form of a thick film tape according to claim 16 , wherein in said heat treatment for calcination, the product of the traveling speed of the substrate and the temperature gradient is preferably 2° C./min or more.
19. The method of producing the oxide superconductor in the form of a thick film tape according to claim 16 , wherein said heat treatment for calcination is carried out at 250° C. or higher in the atmosphere having a water vapor partial pressure of not more than 2.1% by volume.
20. The method of producing the oxide superconductor in the form of a thick film tape according to claim 16 , wherein a difference between the maximum thickness portion and the minimum thickness portion in said thick oxide superconducting film is 1 μm or less.
21. The method of producing the oxide superconductor in the form of a thick film tape according to claim 16 , wherein the amount of change in critical current density is ±0.5 MA/cm 2 .
22. The method of producing the oxide superconductor in the form of a thick film tape according to claim 16 , wherein said thick oxide superconducting film is comprised of RE 1+x Ba 2−x Cu 3 O y (wherein RE represents at least one element selected from the group consisting of Y, Nd, Sm, Gd, Eu, Yb, Pr and Ho; x represents the number of 0≦x≦0.4; and y represents the number of 6.5≦y≦7.0).