Ag Doping Effect on the Superconductivity of Nb3Al Prepared Using High-Energy Ball Milling Method

Abstract

Ag-doped Nb₃Al samples, Nb₃(Al_1.05−<italic>_x</italic>Ag<italic>_x</italic>), with <italic>x</italic> = 0, 0.05, 0.1, 0.15, and 0.2 are synthesized using high-energy ball milling method. At first, the raw materials are found to form Nb(Al, Ag)_ss solid solution after 3 h of high-energy ball milling. With subsequent heat treatment, sintered at 900 °C for 5 h, a transformation from Nb(Al, Ag)_ss into A15 Nb₃Al phase occurred. The σ-phase Nb₂Al diffraction peaks have been observed in the XRD patterns of pure Nb₃Al. However, with Ag doping, no σ-phase Nb₂Al has been detected. SEM images show an obvious difference, where the crystalline grain can be clearly observed in the matrix Nb₃Al phase, but the grain boundary was blurred in the doped samples. The <italic>M</italic>-<italic>T</italic> curve illustrated that the superconducting transition temperature of the Ag doped Nb₃Al compounds decreased with increasing dopants, but slight Ag doping can be effective to stabilize the Nb₃Al A15 lattice.