Preparation and Superconductivity of Fe1-xSeSnx Superconductor

Abstract

Sn doped Fe_1-xSe has been prepared by solid-state reaction through vacuum sintering process at 845^oC for 3 hours and cooled in the closed air tube furnace. Precursor powder (FeSe) was mixed with Sn powder (with purity of 98.5%) obeying a stoichiometric ratio of  Fe:Se:Sn = (1-x) :1 : (x), where x= 1-wt% Sn, 5-wt% Sn and 10-wt% Sn, respectively. The precursor was then inserted into dies to form pellet. The pellet was then  inserted into a crucible and put on quartz tube that aimed to prevent the oxidation of iron during the heating process. Finally, the sample sintered in the furnace tube at 845^oC with heating rate of 5^oC/minute held for 3 hours.The result obtain show that Sn did not actually enter the crystal lattice ?-FeSe, existing as an inclusion Fe instead on 2?=44.38^o. Structurally, the addition Sn doped FeSe superconductors material can increase the volume fraction of the main tetragonal (?-FeSe) from 30.13% to 72.02% at addition of 1 wt%Sn; up to 54.59% at addition of 5 wt%Sn and 51.17% at addition of 10 wt%Sn. The morphology observation also displayed FeSe with the addition of Sn dopant has a large crystallite size with dissipation and the presence of porosity. And result temperature critical at 13.33 K to 15.87 K. All the factors mentioned above are contributed to the high Tc of Sn doped Fe_1-xSe sample. The present work suggests that addition of 1 wt% Sn  might be a promising element in  improvement the superconductivity of Fe_1-xSe.