Co₉S₈ Nano/Microspheres: Characterization and Magnetic Properties

Co₉S₈ microspheres were synthesised by a simple solvothermal route in a binary solution of triethylenetetramine (TETA) and high-purity water (W). Among all the factors that may influence the samples morphologies, volume ratio of TETA and high-purity water are of extreme importance. SEM images show that the microspheres surfaces are coarse with a mean diameter of about 3–5 μm. Their crystallinity can be improved by high temperature annealing. To determine the crystallinity and composition of samples, XRD, EDS and TEM tests were carried out. It can be inferred that these nano/microspheres are amorphous before annealing and crystallized after annealing. Meanwhile a higher element ratio of S:Co can be detected from the annealed samples on EDS results. In the case of magnetism, Co₉S₈ microspheres turn out to be paramagnetic at room temperature.