Preparation of superconducting Y-Ba-Cu-O from a stoichiometric melt by the thermogravimetric method
Chen Changkang; B M Wanklyn; Chen Changkang; Clarendon Lab., Oxford Univ., UK; B M Wanklyn; Clarendon Lab., Oxford Univ., UK
Журнал:
Superconductor Science and Technology
Дата:
1990-11-01
Аннотация:
The superconductor YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7- delta </sub> has usually been produced by sintering or melting the components. In this report, the authors describe the preparation of superconducting YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7- delta </sub> from a stoichiometric melt at the liquidus temperature. The crystallization temperatures were determined by the thermogravimetric analysis method (TGA) for different cooling rates, from which data the liquidus temperature of 1265 degrees C was obtained by extrapolation. The phases that crystallized on the immersed platinum wire were identified by X-ray powder diffraction as being mainly tetragonal YBCO with a very small proportion of the green phase Y<sub>2</sub>BaCuO<sub>5</sub>. After annealing the sample in air at 600 degrees C for 2 h susceptibility experiments showed it to be superconducting with a transition temperature near to 90 K.
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