Direct observation of textured YBa 2Cu 3O 7−δ crystal growth from the melt

Abstract

The behavior and kinetics of textured growth of the YBa 2Cu 3O 7−δ (123) compound from Y 2BaCuO S (211) + liquid have been investigated by hot-stage optical microscopy and high-temperature x-ray diffraction methods. The formation of the 123 is found to begin in the liquid of the peritectic melt, not nucleated from 211 crystals as is widely assumed. The quantity of the liquid phase strongly influences the crystal growth and final morphology of the 123. Dynamic studies show that the optimum temperature for 00 l orientation of 123 is 940°C on an MgO substrate. The growth rate of 123 from the melt is rapid; the rate constant was determined to be 0.526×10 −2S −1.