The microstructures and superconducting properties of FeSe0.5Te0.5 bulks with original milled powders

A combination of mechanical alloying (MA) and solid-state reaction was applied to synthesize bulk FeSe0.5Te0.5 superconductor. The influence of milling time on microstructures and superconducting properties were investigated in detail. The results showed that both the grain size and the amount of β-FeSe in the final sintered samples decreased as the milling time increased. In addition, lattice parameters a and c of β-FeSe also decreased with the milling time increasing, implying the introduction of a positive chemical pressure, which was not favorable for superconductivity of Fe chalcogenides. According to the measured results of resistivity, only the 20 h-milled sintered sample exhibited superconductivity, with Tconset and Tc0 of values 14 K and 10 K, respectively. As the milling time increased, the superconductivity was depressed or even damaged completely.