Mild Hydrothermal-Reduction Synthesis and Mössbauer Study of Low-Dimensional Iron Chalcogenide Microcrystals and Single Crystals

Low-dimensional iron chalcogenide Fe7S8 and FeSe2 microcrystals and FeTe2 bulk single crystals were synthesized via the reactions of FeCl3 with S or Se or Te powders in hydrazine hydrate solution (85%, v/v) at 140 °C for 36 h. The products were characterized by means of X-ray powder diffraction, rocking curve, transmission electron microscopy, electron diffraction, and scanning electron microscopy techniques. In the reaction process, hydrazine hydrate can coreduce Fe3+ and elemental chalcogen to Fe2+ and chalcogen anions, respectively, the combination of which can lead to the reaction proceeding completely. The morphologies of the products are affected by the temperature, pressure, and pH values. Moreover, a suitable speed of decreasing the temperature and proper supersaturation are two important factors in the formation of single-crystal FeTe2. Mössbauer spectra show the magnetism of Fe7S8 and nonmagnetic properties for FeSe2 and FeTe2 at room temperature.