Influence of Oxygen Partial Pressure and Temperature on the Formation and Stability of 110K Phase in the BiPbSrCaCuO Superconducting System

Abstract

<p>A systematic study of the influence of oxygen partial pressure, temperature and time on 110K phase formation in the BiPbSrCaCuO system has been undertaken. The optimum nominal composition to promote the Bi₂Sr₂Ca₂Cu₃Ow (2223, 110K) phase, ie; Bi₁.₈₄Pb₀.₃₄Sr₁.₉₁Ca₂.₀₀Cu₃.₀₄Ow was studied. The relationships between 110K phase fraction, oxygen partial pressure, sintering temperature and time has been mapped for this composition via experimental data. The preferred conditions for 110K phase formation were identified as 0.01 atm≤Po₂≤0.35 atm, at 820≤T≤880°C for ≤36 hours with an intermediate grinding of the material every 6 hours. The optimum conditions for pure 110K phase were Po₂=0.08 atm at 845-865°C for 12 hours with grinding every 6 hours. The oxygen partial pressure range for single 110K phase stability was determined as 0.001 atm</p>