High-T.sub.c superconductor or precursor material for the oxide-powder-in-tube method (OPIT)
AssigneeHoechst Aktiengesellschaft
InventorsMarc Neubacher, Joachim Bock, Christoph Lang, Eberhard Preisler, Helga Weis
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Abstract
The present invention relates to a process for preparing a high-T.sub.c superconductor as a precursor material for the oxide-powder-in-tube method, which involves mixing the oxides of the elements Bi, Sr, Ca and Cu and completely melting them at temperatures of .gtoreq.1000.degree. C., then casting the melt onto a substrate which is kept at room temperature, and disintegrating the cooled melt block and grinding it into a powder.
Claims18
A precursor or high temperature superconductor which has an average grain size of .ltoreq.3 .mu.m and a Fe content of less than 200 ppm prepared according to a process comprising:
- completely melting a mechanical mixture of metal oxides containing bismuth, strontium, calcium, and copper in a stoichiometric ratio corresponding to a superconductor in air at a temperature above 1000.degree. C.,
- pouring the melt out onto a base which is kept at room temperature to cool the melt,
- coarsely breaking up the cooled melt,
- tempering the melt at a temperature between 600 and 900.degree. C. at a defined oxygen partial pressure, and
- disintegrating and grinding the cooled melt into a powder having a carbon content of less than 5000 ppm.
A precursor which has an average grain size of .ltoreq.3 .mu.m and a Fe content of less than 200 ppm for a high-temperature superconductor prepared according to a process comprising:
- completely melting a mechanical mixture of metal oxides containing bismuth, strontium, calcium, and copper in a stoichiometric ratio corresponding to a superconductor in air at a temperature above 1000.degree. C.,
- pouring the melt out onto a base which is kept at room temperature to cool the melt, and
- disintegrating and grinding the cooled melt into a powder having a carbon content of less than 5000 ppm.
A high temperature superconductor article consisting essentially of a first high temperature superconductor which has an average grain size of .ltoreq.3 .mu.m and a Fe content of less than 200 ppm;
- the first high temperature superconductor prepared according to a process comprising:
- completely melting a mechanical mixture of metal oxides containing bismuth, strontium, calcium, and copper in a stoichiometric ration corresponding to a superconductor in air at a temperature above 1000.degree. C;
- pouring the melt out into a base which is kept at room temperature to cool the melt;
- coarsely breaking up the cooled melt;
- tempering the melt at a temperature between 600 and 900.degree. C. at a defined oxygen partial pressure;
- grinding the cooled melt into the first high temperature superconductor precursor powder having a carbon content of less than 5000 ppm.
Dependencies are inferred from the claim text.