Vibrational properties of the mechanochemically synthesized Cu2SnS3: Raman study

Cu2SnS3 (CTS) is a simple and promising material for solar cells. Various physical and chemical techniques have been employed for synthesis of CTS nanocrystals among which mechanochemical synthesis is a great alternative due to its simplicity, solvent-free character, and reproducibility. We present the analysis of the vibration properties of mechanochemically synthesized CTS nanocrystals. The milling time influence on CTS synthesis from elemental precursors Cu, Sn, and S was observed. The scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy was used to characterize the crystal structure and compositional purity of the obtained nanoparticles. In order to investigate the individual steps of the synthesis, samples obtained after 15 s and 5, 10, 15, and 30 min of milling time were analyzed. The detailed analysis of the Raman spectra has allowed us to determine the wavenumber of the main and weaker peaks, and discern the phase, crystal structure, and secondary phases. The formation of monoclinic and tetragonal CTS phases, with oxidized surface (due to milling in air) was confirmed.