Hydrazine-controlled hydrothermal synthesis of Co9S8 from a homogeneous solution

Single-phase nanocrystalline Co9S8 was prepared by hydrothermal treatment of Co(Ac)(2) and NH2CSNH2 in hydrazine solution at 170 degrees C. The products were characterized by x-ray powder diffraction (XRD) technique, transmission electron microscope (TEM), and wet chemical analysis. XRD indicated the product was the cubic Co9S8 phase. The relative crystallite size was 6.3 nm as determined by the Scherrer method. TEM images showed the particles were agglomerative. The electron diffraction pattern also revealed their nanocrystalline nature. In this hydrothermal formation process of Co9S8, hydrazine was a critical factor. The formation process is discussed.