Synthesis of Flower‐Like FeS2 and NiS2 Microspheres Based on Nanoflakes and Nanoparticles: Electronic Structures, Magnetic and Optical Properties

Abstract

Flower‐like spherical micrometer‐sized particles of FeS2 and NiS2 are synthesized using the solvothermal method. The microstructure, phase composition, saturation magnetization and optical characteristics of the synthesized FeS2 and NiS2 are described, and the atomic structure, electronic structure, and optical characteristics of the materials are calculated systematically founded upon the first principles of density functional theory. This work shows that the magnetic saturation intensity of FeS2 and NiS2 is respectively 0.36 and 0.02 emu g−1. The FeS2 and NiS2 bandgaps are separately 0.81 and 2.07 eV, calculated by Tauc's relation. Through the comparison of optical properties, the maximum absorption coefficient of FeS2 and NiS2 is separately 3.26 × 105 and 3.3 × 105 cm−1, and the two crystals’ absorption coefficient accordingly drops to 0 at 23.8 and 25.8 eV, indicating that the maximum absorption value and energy absorption range of NiS2 are higher than those of FeS2. The reflectivity above 60% ranges from 15.3 to 20.6 eV and 15.2 to 21.5 eV for FeS2 and NiS2, respectively, which indicates that the reflectivity of NiS2 is stronger than that of FeS2.