Effect of substitution and heat treatment route on polycrystalline   FeSe0.5Te0.5 Superconductors
  The effect of atomic substitution of Te in iron based superconductors FeSe (1:1 type), which exhibits the simplest crystal structure among the iron-based superconductors, has been investigated in terms of structural, electronic transport and magnetic properties. Polycrystalline samples with nominal Se:Te in FeSe1-xTex samples for x=0.5350{\deg}C, 0.5700{\deg}C, 0.6700{\deg}C and 0.75700{\deg}C were synthesized by the solid-state reaction method. It has been observed that the most superconducting properties seen in x=0.6700{\deg}C samples as dc magnetic susceptibility, ac susceptibility and resistivity measurements. Tc enhancement is well correlated with the Te substitution up to 75% and c lattice parameters monotonically increased with increasing Te concentration. 
Muammer Yasin Hacisalihoglu, Ekrem Yanmaz
cond-mat.supr-con cond-mat.mtrl-sci