Properties of high-energy ball-milled Fe-Se based superconductors.

We have synthesized FeSe0.5Te0.5 superconductors by high-energy ball-milling and subsequent annealing. High-energy ball-milling of elemental powder mixtures resulted in the formation of metastable and/or nanocrystalline phases. Both XRD and DSC results show that the ball-milled powers were completely transformed to FeSe0.5Te0.5 with the grain size of a few nanometers during sintering at low temperatures. The resulting materials exhibited superconducting transition at 14 K. The enhancement of critical current density was observed for the high-energy ball-milled powder, compared with the un-milled powders.