A comparison of the effects of PtO₂and BaSnO₃additions on the refinement of Y₂BaCuO₅and magnetization of textured YBa₂Cu₃O_6+x

Abstract

Y2BaCuO5 (211) and liquid (L=3 BaCuO2:2CuO) were used as the precursor materials to study the effect of additions of BaSnO3 and PtO2 on the coarsening behaviour of 211 particles in the liquid above the peritectic temperature of YBa2Cu3O6+x (123), and the magnetic properties after melt texturing. Additions of BaSnO3 and PtO2 both reduced the coarsening of 211, but PtO2 did so much more effectively. The PtO2 additions were found to refine 211 by altering the 211/liquid interfacial energy and/or Y diffusivity, and not by acting as heterogeneous nucleation sites. BaSnO3 additions were found to not be inert in the melt. They reduce 211 coarsening by acting as a Y sink. Magnetization measurements at 20, 40 and 60 K on crushed melt-textured 123 samples showed enhanced intragrain flux pinning effects in samples prepared from 211+L+PtO2 as compared with 211+L+BaSnO3 or 211+L precursor samples.