Effect of oxygen partial pressure on the preparation of phase-pure YbBa2Cu3O7-y superconductor by solid-state sintering method

Abstract

In preparing REBCO superconductors, the oxygen partial pressure (PO₂) was an important factor that must be considered. In this work, as a typical REBCO superconductor, YbBa₂Cu₃O_7-δ (Yb123) was prepared by solid-state sintering in Ar (100 %), Ar (99.8 %)-O₂ (0.2 %), Ar (99 %)-O₂ (1 %), Ar (98 %)-O₂ (2 %) and air atmospheres, and the effect of PO₂ on the preparation of Yb123 was systematically investigated. The results showed that phase-pure Yb123 samples could be prepared in Ar (99 %)-O₂ (1 %) at 1113 K and Ar (98 %)-O₂ (2 %) at 1133 K, and the samples’ critical transition temperatures were about 90 K. In contrast, Yb123 could not be formed in Ar (100 %) and Ar (99.8 %)-O₂ (0.2 %) atmospheres, suggesting that there was a critical value of PO₂ while preparing Yb123. Furthermore, the relationship between the PO₂ and the optimum temperature range for synthesizing high phase-purity Yb123 could be quantitatively expressed as 30002/T = - lgPO₂/P^o + 24.9.