Shape Evolution and Magnetic Properties of Cobalt Sulfide

In this work, well-defined uniform octahedrons of Co 3 S 4 are synthesized via a simple biomolecule-assisted hydrothermal process for the first time. Evolution of the crystal-structure and the shape of the samples are examined systematically by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The formation mechanism of the octahedral Co 3 S 4, possibly due to a ripening-splitting crystal growth process, and the effect of microstructure and morphology on their physical properties are investigated. This work may not only render a simple approach to synthesize highly symmetric, microstructured materials but also could provide fundamental insights of the effect of crystal structure transformation on physical properties.