TiO2 Nano-doping Effect on Flux Pinning and Critical Current Density in an MgB2 Superconductor

Abstract

We have studied the TiO2 doping effects on the flux pinning behavior of an MgB2 superconductor synthesized by the in-situ solid-state reaction. From the field-cooled and zero-field-cooled temperature dependences of magnetization, the reversible-irreversible transition of TiO2-doped MgB2 was determined in the H-T diagram (the temperature dependence of upper critical magnetic field and irreversibility line). For comparison, the similar measurements are also obtained from SiC-doped MgB2. The critical current density was estimated from the width of hysteresis loops in the framework of Bean's model at different temperatures. The obtained results manifest that nano-scale TiO2 inclusions served as effective pinning centers and lead to the enhanced upper critical field and critical current density. It was concluded that the grain boundary pinning mechanism was realized in a TiO2-doped MgB2 superconductor.