Growth of Bi 2Sr 2CaCu 2O 8 + x single crystals at different oxygen ambient pressures

Abstract

Bi-2212 superconducting single crystals were grown by the travelling solvent floating zone method at different oxygen ambient pressures. Electron probe micro-analysis showed a systematic increase of the Sr/ Ca ration in the as-grown crystals with increasing oxygen ambient pressure and a maximal superconducting transition temperature of T c- onset = 95 K, and ΔT c = 1.5 K was obtained for crystals grown at an oxygen ambient pressure of 200 kPa. Thermogravimetric and post-annealing experiments in air at 500 and 800°C have shown that the oxygen content and the T c-onset values in the crystal do not depend only on the annealing temperature, but also on its chemical composition. The in-field current density J c measured at 5 K on crystals grown at 200 kPa oxygen ambient pressure was considerably smaller than that of crystals grown in air.