Synthesis and Characterization of Cu₂FeSnS₄-Cu₂MnSnS₄ Solid Solution Microspheres

In this study, we used a hydrothermal method to synthesize microspheres of Cu₂(Mn_1-xFe_x)SnS₄ solid solution (X = 1, 0.8, 0.6, 0.4, 0.2, 0). The process was optimized to improve the crystallinity, morphology, and purity of the obtained materials. All samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The following conditions were optimized: A mixture of water and ethylene glycol at the ratio of 1:7 as the reaction medium, polyvinylpyrrolidone (PVP) as the surface ligand, and reaction temperature of 195 °C for 7 days. The product of synthesis precipitated in the form of aggregates of nanocrystals, which form homogeneous, often concentric microspheres with a diameter of 1-1.5 μm. The chemical composition of the product can be well controlled by the chemical composition of the reactants. The compound Cu₂(Mn_1-xFe_x)SnS₄ forms a continuous series of solid solutions.