The effect of the sintering process on Ag–added FeSe0.94 superconducting wire

Abstract

We investigated the effect of different sintering processes on Ag–added FeSe0.94 superconducting wires. After applying different sintering procedures, we successfully obtained zero resistivity, at 350 °C for 100 h and at 700 °C for 1 h, in Ag–added FeSe0.94 superconducting wire produced using the ex-situ powder-in-tube method. The crystal structure of both wires is mainly composed of the tetragonal β–FeSe phase. Ag does not react with selenium, and it can be incorporated into the crystal structure. The transport Jc value of these wires is calculated to be 24.4, and 38 A cm−2 at 4.2 K in a self-field, respectively. The low current densities of the wires are attributed to the low core–density and the presence of porosity. The upper critical field is estimated to be 16.2 and 14.6 T from Werthamer–Helfand–Hohenberg theory, respectively.