Effect of the Presence of Structural Defects on the Superconducting Properties of (NbTa)_0.67(MoHfW)_0.33 and Nb-47wt%Ti

Abstract

A comparison of the results of studies on the influence of structural defects on the critical parameters of superconductivity has been made for the high-entropy alloy (NbTa)0.67(MoHfW)0.33 and for the conventional superconducting magnet material Nb-47wt%Ti. Positron annihilation lifetime spectroscopy (PALS), electrical resistivity, magnetization and magnetic susceptibility measurements were used. In addition, X-ray powder diffraction studies were performed on the high-entropy alloy (NbTa)0.67(MoHfW)0.33. Due to the rapid cooling of the materials after melting in the arc furnace, they contain a higher concentration of structural defects compared to the heat-treated materials. Magnetic property measurements showed that both the critical temperatures Tc and the upper critical fields μ0Hc2 of bulk superconductivity-related materials are improved in the presence of structural defects.

Keywords

• high-entropy alloy
• superconductivity
• X-ray powder diffraction
• magnetic susceptibility measurements
• positron annihilation lifetime spectroscopy