Crystal structure refinements of stoichiometric NiSe and NiSe.

Single crystals of NiSe (trinickel diselenide) and NiSe (nickel selenide) with stoichiometric chemical compositions were grown in evacuated silica-glass tubes. The chemical compositions of the single crystals of NiSe and NiSe were determined by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS). The crystal structures of NiSe [rhombohedral, space group R32, a = 6.