Solvothermal synthesis of metastable γ-MnS hollow spheres and control of their phase

A solvothermal route has been developed to prepare metastable wurtzite -structure gamma-MnS hollow spheres from anhydrous manganese chloride, sulfur powder, and potassium borohydride in ethylene glycol at 150-180 degrees C. The metastable gamma-MnS and stable alpha-MnS were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electronic microscopy, scanning electron microscopy, transmission electron microscopy, and photoluminescence. Experiments show that the reaction temperature, the solvent, and the concentration and reducibility of the reductant are the crucial factors affecting the phase of the product. A possible growth mechanism for the hollow sphere is proposed. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).