Synthesis, crystal growth and superconducting properties of Fe-Se system

Single crystals FeSex were grown in an evacuated sealed quartz tube using polycrystalline material by gas-transport reaction with I2 as a gas-carrier. Crystals with hexagonal-prismatic, tetragonal-prismatic, planar-square and hexagonal faceting 0.1 to 0.5 mm in size were obtained. The electronic transport and magnetic prop-erties measurements of FeSex single crystal exhibit an onset of superconducting transition Tc at up to 24 K.