Metastable MnS crystallites through solvothermal synthesis

Metastable (beta and gamma) and stable (alpha) MnS crystallites were synthe sized by solvothermal reaction in various solvents at 190-200 degreesC. In tetrahydrofuran and benzene, the metastable MnS crystallites can be obtaine d. In water, ammonia liquor, ethylenediamine, alpha -MnS, which is converte d from the metastable phase, would be obtained. The low solubility of MnS i s the crucial reason to stabilize the metastable phase with good yield. The metastable MnS crystallites were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The meta stable gamma -MnS crystallites with rodlike morphology were found, and a un ique "methane-like" four-branched rod cluster was characterized. The blue s hift of the absorption edge indicates the quantum size effect of metastable MnS nanocrystallites.