Effect of Te doping on FeSe superconductor synthesized by powder-in-tube

FeSe is a superconducting material, which has the simplest crystal structure among the Fe-based superconductors. It has no arsenic element, which is very harmful to the human body. In this study, we analyzed the effects of milling time and Te doping on FeSe superconductors. The synthesis of the samples were carried out using powder-in-tube method in a SS304 stainless steel tube. After the pressing process, followed by the sintering process at 500 degrees C for 20 hours, the samples were removed from the tubes. Later, we analyzed its crystal structures, surfaces morphology and the superconductivity properties. delta-FeSe phase (hexagonal, non-superconductor) and beta-FeSe (tetragonal, superconductor) were formed in the samples, including minor phases of Fe and Fe3Se4. Te doping changed the crystal structure from beta-FeSe and delta-FeSe into FeSe0.5Te0.5. In addition, the onset critical temperature (T-C,T- onset) shifted to higher temperature.