Effects of Preparation Conditions and Mechanical Polishing on the Superconducting Behavior of High-Tc Oxide Y1Ba2Cu3O7-y

Abstract
We investigated the effects of preparation conditions and mechanical polishing on the resistance-temperature characteristics of superconducting oxides, Y1Ba2Cu3O7-y which were prepared from different starting materials of (1) Y2O3, Ba(NO3)2 and Cu(NO3)2 (A-series) and (2) Y2O3, BaCO3 and CuO (B-series). The A-series samples were ten times more closely packed than the B-series samples. It was found that mechanical polishing of the specimen surface was necessary to obtain stable and reproducible resistance-temperature characteristics. In addition, the specimen, which was prepared from the A-series starting material, gave the best zero-resistance result at 95.5 K.