Controlled growth of pyrite FeS2 crystallites by a facile surfactant-assisted solvothermal method

A simple surfactant-assisted ethylene glycol-mediated solvothermal method is reported for the synthesis of pyrite crystallites with cubic and octahedral shapes for the first time. The process involved the reduction of sulfur and the reaction between S2- and Fe2+ in the presence of surfactant. By changing the concentration of NaOH and properly adjusting some other experimental parameters, pyrite crystallites with a defined crystalline structure have been realized. It was demonstrated that the different surfactants can adsorb on certain faces selectively, the subsequent competing growth between [100] and [111] directions directed the final shape of the particles. NaOH was found to be crucial for the formation of the pyrite cubes and octahedral crystallites by not only acting as the pH regulator but also determining the reduction ability of ethylene glycol. The influences of solvothermal temperature, the dosage of sulfur, the concentration of NaOH and the kinds of the surfactants on the shape of the crystallites were investigated systematically. The magnetic properties were also studied. Moreover, the method demonstrated here could be of great potential for controlling the synthesis of other metal chalcogenides with controlled shapes and structures.