Synthesis of well dispersed cobalt disulfide and their photoluminescence and magnetic properties

We used a facile solvothermal method to synthesize well dispersed pyrite cobalt disulfide nanoparticles by using sulfur powder and ethylenediamine as sulfur source and solvent, respectively. The chemical composition of the nanoparticles is determined to be CoS1.931. These nanoparticles are of spherical and quasi-spherical shapes, and the diameters are in the range from 20 to 60 nm. Photoluminescence spectra show two emission bands centered at 411 and 532 nm, respectively. Magnetic measurement indicates a broad homogeneous ferromagnetic–paramagnetic transition with Tc ca. 140 K. It is found that intrinsic point defects including VS, Coi, CoS, Si may be the main reason for the unusual emission bands and increased Tc.