| The Changes in microstructure during melting and solidification of YBa₂Cu₃O_(7-x) were observed and YBa₂Cu₃O_(7-x) wires were fabricated by the melt textured growth method. The YBa₂Cu₃O_(7-x) phase, when heated at 1050℃ for 10 min., was decomposed to Y₂BaCuO_5 and liquid phase. When the Y₂BaCuO_5 and liquid were cooled to form YBa₂Cu₃O_(7-x), the Y₂BaCuO_5 particles dispersed in the liquid grew fast while the growth rate of the entrapped particles in the YBa₂Cu₃O_(7-x) phase was negligible. Even after the completion of the peritectic reaction, Y₂BaCuO_5 particles remained within the YBa₂Cu₃O_(7-x) grains. Slower cooling rate during and after the peritectic reaction resulted in the larger YBa₂Cu₃O_(7-x) grain size. The transition temperatures of 85K and 79K were obtained at the cooling rates of 9℃/hr and 2℃/hr, respectively. However the wire obtained at 1℃/hr did not show superconductivity at the liquid nitrogen temperature of 77K. |
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