Growth of FeSe 0.5 Te 0.5 crystals with (001) preferred orientation by chemical-furnace-assisted combustion synthesis

Iron-based superconductor of FeSe0.5Te0.5 has been prepared by chemical-furnace-assisted combustion synthesis. The chemical furnace preheats the reactant and enhances the reaction temperature, thus increasing the volume fraction of liquid and the solubility of Fe and improving the mass transfer. Accordingly, the chemical reaction and crystal growth are greatly promoted, resulting in higher compositional homogeneity, better crystallinity, and larger crystal size. The synthesized FeSe0.5Te0.5 sample consists of two-dimensional thin slice crystals. It is proposed that, the slice crystal shape is derived from the intrinsic tetragonal lattice of FeSe0.5Te0.5, and forms by anisotropic crystal growth with fast growth in (001) face. The crystal growth of FeSe0.5Te0.5 is also affected by cooling condition, and by control of the cooling condition lamellar crystals are produced with a thickness of about 1 mm and (001) preferred orientation. The transport properties of the synthesized FeSe0.5Te0.5 sample have been investigated, showing an onset Tc of about 13 K in the resistivity vs. temperature curve and a sharp drop of magnetic susceptibility at about 15 K. Compared with the conventional solid state reaction approach, chemical-furnace-assisted combustion synthesis may provide a more efficient way to prepare iron-based superconductors with much-reduced processing time and not requiring furnaces.