Molten salt synthesis and luminescence properties of Bi4Si3O12 powders

In this paper, Bismuth silicate (Bi4Si3O12, BSO) powders were prepared by reaction in molten salts (NaCl and KCl) using Bi2O3 and SiO2 powders as raw materials. The effects of salt contents and excessive contents of Bi2O3 and SiO2 were characterized by X-ray diffraction and scanning electron microscopy. The properties of Bi4Si3O12 powders were analyzed via fluorescence spectroscopy. Forming mechanism of platelets was discussed. The experimental results suggest that Bi4Si3O12 powders are produced at 780 °C for 4 h with 40 wt% salts and 5 wt% excessive content of Bi2O3. The peaks of excitation spectrum and emission spectrum for BSO powders are separately located at 266 and 457.6 nm. Compared with crystal materials, the excitation spectrum and emission spectrum of Bi4Si3O12 powders indicate blue shift. Interface reacting mechanism can be used to explain the coarsening process of bismuth silicate platelets produced in molten salt synthesis. In addition, dissolution–precipitation mechanism also plays an important role in the synthesis of bismuth silicate platelets.