On the Growth Behavior of Superconductive Crystals YBa_2Cu_3O_χ

Abstract

Single crystals of oxide superconductor YBa_2Cu_3O_χ have successfully been grown using a slow cooling method where a slight excess of CuO is used in order to make a partial melting condition. Two types of crystals are obtained: block crystals with the aspect ratio of about 0.5, and flake ones with that of about 0.1. The former displays a sharp transition m superconductivity above 90 K, whereas the latter shows a gradual one below 60 K. The former crystals are thought to be made in a condition that solid and liquid phase coexist and a peritectic reaction plays a main role. On the other hand, the latter crystals may be grown under a solution growth condition. Growth condition and mechanism are discussed using the results of microscope observation, SEM-EPMA and quenching experiments.