Novel approaches in the melt-texturing of YBa₂Cu₃O_7−y

Abstract

Electrochemically pre-textured samples have been subjected to melt-processing in order to produce dense and highly textured bulk samples of YBa₂Cu₃O_7−y (YBCO). Full oxygenation of these samples has been achieved at high processing temperatures of 720 °C by electrochemical titration, in order to increase the superconducting transition temperature to > 89 K. These samples show a large magnetic hysteresis, and the value of J _c calculated using the Bean model is in the range 4000–6000 A cm⁻² at 77 K and 1 tesla magnetic field, and is independent of the applied field in that range. In another variation of the melt-processing technique — referred to as “isothermal melt-textured growth” — highly textured samples have been produced by the movement of the solidification front at a constant temperature in an oxygen activity gradient.