Growth and Investigation of Crystals of the New Superconductor α-FeSe from KC1 Solutions

Crystals of FeSe0.88 and FeSeMn0.1 have been grown from KCl solutions. Crystals measuring 2-3 mm across and 0.1-0.3 mm thick grow with a hexagonal plate like habit. Powder X-ray diffraction (XRD) measurements show strong peaks corresponding to the tetragonal alpha-FeSe phase and weak hexagonal beta-FeSe peaks in both cases. The plate side of the crystal is identified to he the (101) face of the tetragonal alpha-FeSe. Energy dispersive X-ray spectroscopic (EDS) measurements show that Mn substitutes for Fe. Both types of crystals show a superconducting transition at 8 K in the DC magnetization measurements and a broad resistive transition with zero resistance at 7.5 K with an onset at 11 K. Specific heat measurements also confirm bulk superconductivity in the crystals. Crystals could also be grown using KBr as a solvent.