Evolution of Structural, Thermal, Optical, and Vibrational Properties of Sc₂S₃, ScCuS₂, and BaScCuS₃ Semiconductors

In the present work, we report on the synthesis of Sc₂S₃, ScCuS₂ and BaScCuS₃ powders using a method based on oxides sulfidation and modification of their properties. The crystal structures and morphology of samples are verified by XRD and SEM techniques. Thermal stability has been studied by DTA which has revealed that Sc₂S₃ decomposes to ScS through melting at 1877 K. ScCuS₂ and BaScCuS₃ melt incongruently at temperatures of 1618 K and 1535 K, respectively. The electronic structure calculations show that the investigated compounds are semiconductors with indirect band gap (E_g). According to the diffuse reflection spectroscopy, Sc₂S₃, ScCuS₂ and BaScCuS₃ are wide‐bandgap semiconductors featured the E_g values of 2.53 eV, 2.05 eV and 2.06 eV, respectively. The band gap decreases with the introduction of copper (I) and barium cations into the crystal structure of the compounds. Variation of local structure has been verified by Raman and infrared spectroscopy. The calculated vibrational modes of ScCuS₂ correspond to CuS₄ and Sc−S layer vibrations, even though ScS₆ octahedra‐like structural units can be found in the structure.