Microstructural properties of Pt-doped YBa₂Cu₃O_7−x high-T _c superconductor prepared by melting method

Abstract

We have studied the effect of platinum addition on the superconducting properties of YBa₂Cu₃O_7−x (123) compound and elucidated from the metallurgical point of view the mechanism of formation of the fine dispersion of Y₂BaCuO₅ (211) particles in YBa₂Cu₃O_7−x superconductor prepared by a melting method. In this study, the amounts of BaCuO₂ and CuO-rich phases unreacted during the peritectic reaction were markedly decreased by the 211 powder addition. The 211 particles of Pt-free sintered samples were 8–10 Μm in size, but in 1 wt% Pt-added samples 211 particles were finely dispersed in the 123 matrix and the size of 211 particle was about 1–2 Μm. The critical temperature (T _c,zero) of Pt-doped samples was 91.5 K and the transport critical current density (J _c) of Pt-doped samples was much more than 10⁴A cm⁻². The high J _c and fine dispersion of 211 particles of Pt-doped YBa₂Cu₃O_7−x superconductor are attributed to Ba₄CuPt₂O₉ compounds formed during the partial melting, which were considered as nucleation sites of 211 particles, rather than Pt itself.