The thermal stability of the superconducting phase of nominal composition YBa 2Cu 3O 7-x-sintered pellets has been studied with respect to different temperatures (ranging from 300 to 950° C), time (ranging from 1 to 72 h), oxygen partial pressure (from 4 Pa to 1 atm) and carbon dioxide partial pressure (from 10 -4 Pa to 1 atm). Annealed samples were characterized by X-ray diffraction analysis, optical microscopy, and resistive measurements of the superconductive transition temperature. A stability field of the orthorhombic and tetragonal phases was obtained, showing a region of coexistance. The decomposition of the 1 2 3 phase is found to be strongly influenced by the presence of a small amount of CO 2 (1 p.p.m.) in the sintering atmosphere. A sintering process is proposed to avoid the formation of by-products. © 1990 Chapman and Hall Ltd.

A study on the stability of superconducting yttrium barium copper oxide (YBa2Cu3O7-x) phase

MARINO, OTTAVIO;PERNICE, PASQUALE;PEPE, GIOVANNI PIERO;SCOTTI DI UCCIO, UMBERTO
1990

Abstract

The thermal stability of the superconducting phase of nominal composition YBa 2Cu 3O 7-x-sintered pellets has been studied with respect to different temperatures (ranging from 300 to 950° C), time (ranging from 1 to 72 h), oxygen partial pressure (from 4 Pa to 1 atm) and carbon dioxide partial pressure (from 10 -4 Pa to 1 atm). Annealed samples were characterized by X-ray diffraction analysis, optical microscopy, and resistive measurements of the superconductive transition temperature. A stability field of the orthorhombic and tetragonal phases was obtained, showing a region of coexistance. The decomposition of the 1 2 3 phase is found to be strongly influenced by the presence of a small amount of CO 2 (1 p.p.m.) in the sintering atmosphere. A sintering process is proposed to avoid the formation of by-products. © 1990 Chapman and Hall Ltd.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11588/479549
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