Effect of Oxygen Partial Pressure on Phase Formation and Stability of LuBa2Cu3O7−x Compounds

Abstract

Among the several R-123-type (R = rare-earth element) superconductors, it has been reported that LuBa2Cu3O7−x(Lu-123) could not be prepared as single-phase superconducting ceramics at temperatures between 900 and 1000 °C both in air and in pure O2. We present here the results of our investigations of the synthesis and structural stability of nearly phase-pure ceramic Lu-123 compounds prepared by a solid-state reaction route. It is found that the phase-pure Lu-123 compound can be formed within a narrow range of oxygen partial pressure in the temperature range of 880–900 °C. It is also found that the Lu-123 phase becomes unstable due to the structural decomposition at temperature above 800 °C in N2 and in pure O2 of 1 atmosphere, and above 830 °C in air.