Mechanochemical synthesis of BiSI and Bi19S27I3 semiconductor materials

With regard to the intensive investigations of bismuth oxyhalides as promising photocatalysts, much expectation may be put on the corresponding chalcohalides but little is known due to difficulty in the synthesis. In this report, BiSI and Bi19S27I3 were synthesized by one-step mechanochemical method without heating and aqueous operations and the products were characterized by X-ray diffraction crystallography, Raman spectroscopic analysis, X-ray photoelectron spectroscopy analysis, photoluminescence spectra and UV-visible DRS. The new method allowed the simple syntheses of pure bismuth chalcohalides without observable existences of impurity phases. The crystal structures of BiSI and Bi19S27I3 were orthorhombic, with the absorption band gaps of 1.80 and 1.14 eV for BiSI and Bi19S27I3, respectively. Bi-rich compound is considered to be beneficial to the photochemical property of chalcohalides. After overcoming the difficulty in the synthesis, our research would offer new strategy to exploit the potentials of V-VI-VII compounds, particularly of sulfides, as promising semiconductors to compete the corresponding counterparts of oxides. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.