Synthesis of CoS nanoplates and their ferromagnetic properties

We developed a facile solvothermal method to fabricate CoS nanoplates by using thioacetamide as a new sulfur source. It is found that thioacetamide can slowly release S ions during the solvothermal process, and the S ions can further bind Co ions to form hexagonal CoS nanoplates. The actual composition of the nanoplates is determined to be non-stoichiometric CoS0.916. Photoluminescence spectra of the nanoplates indicate two emission bands centered at 544 and 578 nm, respectively. Moreover, room-temperature ferromagnetism is detected in these nanoplates. We deduce that intrinsic point defects including VS, Coi, CoS, Si and/or their complex defects are the main reasons for the unusual photoluminescence emission and the room-temperature ferromagnetism.

► We use thioacetamide as a new sulfur source for fabricating CoS nanoplates. ► The actual composition of the nanoplates is non-stoichiometric CoS0.916. ► Point defects should be responsible for the PL emission and RT ferromagnetism.