Origin of superconductivity in copper niobium alloys

摘要: Superconductivity in copper‐rich niobium alloys has been investigated. A controlled cooling technique was developed to provide homogeneous distributions of the copper. Two distinct microstructures were observed depending on rate. For low rates (<700 °C/sec) and concentrations a subgrain structure is evident. These samples are superconducting with critical current density (<10 A/cm2). faster (≳1000 °C/sec) eliminated concentration for observation superconductivity experimentally at 10–12 wt% Nb (7–9 at.% Nb). The determined explained by model based site percolation theory modified shape precipitate. suggests that continuous chains copper matrix lead properties. proximity effect, previously suggested as basis these alloys, ap...