Low-temperature Synthesis of Micro- and Nano-Crystalline CuFeS2 Polymorphs

Micro- and nano-crystalline polymorphs of CuFeS 2 have been synthesized by using simple, low temperature solvothermal and precipitation methods. A solvothermal process at 170 °C, using ethylenediamine produced micro- and nano-crystalline CuFeS 2 with various shapes and morphologies, which include polygons, pyramids, hexagonal rods and plates etc. In addition to the expected tetragonal, chalcopyrite phase, a new, relatively low symmetry, hexagonal, wurtzite phase of CuFeS 2 was also obtained. The wurtzite phase fraction was found to be ~21 wt% by Rietveld analysis using X-ray powder diffraction data. Further, the effects of solvent concentration, reaction temperature and annealing on the crystallites have been studied. By the solvothermal process carried out at 140 °C, hexagonal, wurtzite phase CuFeS 2 was obtained with a phase fraction as high as ~92 wt%. A relatively, simple and low-temperature precipitation process using (NH 4 ) 2 S and distilled water produced micro- and nano-crystalline CuFeS 2 with various shapes including rods, hexagonal plates, and spheres etc. The synthesis methods reported here are believed to be beneficial for the further development of CuFeS 2 in the field of nanotechnology.