Addition of Sb2O5 into MgB2 Superconductor Obtained by Spark Plasma Sintering

Abstract

High-density (92–98 % of the theoretical density) MgB 2 samples added with Sb 2O5 ((MgB 2)+ (Sb 2O5)x,x= 0, 0.0025, 0.005, 0.015) were obtained by Spark Plasma Sintering. A higher amount of additive decreases density. In added samples, grains of secondary phases are located at MgB 2 grain boundaries and they are of large size. Hence, Sb 2O5 does not promote effective flux pinning, connectivity is lower, and this suppresses the critical current density and the irreversibility field. Pinning force-related parameters indicate that added samples are close to the point pinning region and they show a higher grain boundary pinning contribution when compared with pristine MgB 2 sample and when temperature is lower. It is speculated that for fixed processing conditions and Sb-oxide phases, a lower stability of the additive, reflected by a lower melting temperature, may promote reactive processes to start earlier leading to coarsening of the grains belonging to secondary phases.