Monodisperse cubic pyrite NiS2 dodecahedrons and microspheres synthesized by a solvothermal process in a mixed solvent: thermal stability and magnetic properties

Abstract

Monodisperse cubic pyrite NiS₂ dodecahedrons and microspheres with a diameter of 6 µm have been synthesized by a solvothermal approach in ethylenediamine–glycol mixed solvent at 200 °C using NiCl₂·6H₂O and sulfur as precursors. The morphology and the phase transformation of the products were found to be strongly dependent on the reaction temperature, reaction time, and the volume ratio of ethylenediamine to glycol. The thermal stability of the pyrite NiS₂ dodecahedrons has been studied and they can act as excellent templates for synthesis of porous NiO microspheres by calcination in air. The NiS₂ dodecahedrons show antiferromagnetic properties between 10 and 300 K. The present solvothermal approach in a mixed solvent system may allow to synthesize other metal chalcogenides with unique shapes and structures.