JPH01133906A - Production of oxide superconductor - Google Patents

Abstract

PURPOSE:To obtain an oxide superconductor having a high critical temp. with high reproducibility by treating precursors of the constituent elements of an oxide superconductor in an oxygen atmosphere and subjecting the resulting oxide superconductor to reduction treatment in a hydrogen atmosphere. CONSTITUTION:Precursors of the constituent elements of an oxide superconductor are treated in an oxygen atmosphere and the resulting oxide superconductor is subjected to reduction treatment in a hydrogen atmosphere. Since the amt. of oxygen in the oxide superconductor can be made smaller by reduction, the concn. of oxygen is controlled to the optimum value to increase the critical temp.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing an oxide superconductor suitable for use in power transmission, magnetic levitation, and Josephine elements, and particularly relates to an improvement in the critical temperature 1j+c. It was planned.

<Prior art> As a manufacturing method of this type, ■Ba is a superconductor constituent element.
A method in which particles of oxides such as , Y, and Cu are mixed and then melted and slowly cooled in an oxygen atmosphere. A method of epitaxial growth on a substrate using reactive sputtering using the same oxide particle powder as described in ■■ as a target. (2) There is a method of epitaxially growing a superconducting thin film using a CVD method using an organometallic compound such as Ba, Y, or Cu as a starting material.

<Problems to be Solved by the Invention> However, there is a problem in that the properties of the superconductors obtained by these methods vary widely and a stable Tc cannot be obtained. The reason is that the superconducting phenomenon is based on Ba-Y-Cu-
This l! ! It is very difficult to control the state of 2-element deficiency, and it has been difficult to increase Tc, which is a characteristic of superconductivity, to a large value with good reproducibility.

Means for Solving the Problems> From the above points of view, the present invention is based on the method of first treating a precursor of an oxide superconductor in an oxygen atmosphere to obtain a superconductor, and then reducing the superconductor with hydrogen to reduce the oxygen concentration. This is an attempt to improve Tc by controlling the oxygen concentration and thereby achieving the optimum oxygen concentration. Note that in the reduction with Hl, the concentration of 02 can be adjusted freely by appropriately selecting the treatment time and temperature.

Further, as a means for obtaining the oxide superelectric material, a firing method, a sputtering deposition method, a CVD method, a sol-gel method, etc. can be employed as in the conventional method.

For example, when using the CVD method, barium acetylacetonate (BaC
Possible combinations include CtHyO*)x), cyclopentagenyl yttrium CY(CsHs)s), and hexafluoroacetyl.

<Example> KunoY, Ba, and Cu oxides were mixed at a molar ratio of 1:2:3, melted at 800°C in an oxygen atmosphere, and then gradually lowered by 50°C per hour to 500°C. The mixture was cooled, maintained at this temperature for 2 hours, and then slowly cooled down to 300°C by decreasing the temperature by 30°C per hour.

The thus obtained Yl.Ba,.Cu,.0. -x
The Tc of the oxide crystal was 606. This sample was placed in a quartz furnace tube, and a mixed gas containing He and H3 at a ratio of 95:5 was pumped into the interior for 6 hours.

Next, the temperature inside the furnace was raised to 200°C at a rate of 50°C per hour, and then to 300°C at a rate of 30°C per hour, and the treatment was carried out at this temperature for 2 hours. After that, 950℃ per hour
The temperature was gradually lowered to room temperature. The Tc of the sample obtained by smelting was 100 @, and the characteristics were improved when compared with that before reduction with H8.

<Effects of the Invention> As described above, the present invention provides oxygen (0) in an oxide superconductor.
The amount of oxygen (0
) is excessive, it can be adjusted to the optimum value (:) for the superconductor once obtained, thereby making it possible to control Tc.

Further, since oxidation and reduction, that is, oxygen treatment and hydrogen treatment can be applied to any superconductor (or any pair) as necessary, it is possible to suppress the occurrence of defective products and improve the yield.

Patent applicant: Fujikura Electric Wire Co., Ltd. Agent Patent Attorney Mamoru Takeuchi

Claims (3)

[Claims] (1) A method for producing an oxide superconductor, which comprises treating a precursor of a constituent element that will become an oxide superconductor in an oxygen atmosphere to form a superconductor, and then reducing the superconductor in an H_2 atmosphere. (2) The method for producing an oxide superconductor according to claim 1, wherein the precursor is an oxide of a constituent element that will become the oxide superconductor. (3) The method for producing an oxide superconductor according to claim 1, wherein the precursor is an organic substance that is a constituent element of the oxide superconductor.