Melt Processing of YBaCuO and Critical Current Characteristics

Abstract

We report a novel melt process, or the MPMG (Melt-Powdering-Melt-Growth) process, for YBaCuO superconductors which promises high critical current density. It is important to disperse the Y₂BaCuO₅ (211) phase finely in the liquid in order to promote the continuous growth of the YBa₂Cu₃O_x (123) phase from the melt, because the 123 superconducting phase in YBaCuO system is produced by a peritectic reaction, Y₂BaCuO₅ (211)+L(liquid)→2YBa₂Cu₃O_x (123). We employed the process of pulverizing and well-mixing the oxides after cooled from partially melted region of 1, 200°C-1, 400°C, in order to achieve the fine dispersion of the 211 phase. The MPMG process has three advantages, 1) it can achieve the fine dispersion of the 211 phase, therefore the continuous growth of the 123 phase, resulting in high critical current density, 2) it is easy to form the samples in various shapes and sizes, and 3) it is possible to control the volume fraction of 211 inclusions by simply changing the starting compositions.