Nanocrystallites in Bi–As–S system

Abstract Bi 2 S 3 –As 2 S 3 composite formation was performed by two methods: by the direct insertion of Bi 2 S 3 nanocrystals into a molten As 2 S 3 glass which was further solidified and by the crystallization of a rapidly quenched (As 2 S 3 ) 1− x (Bi 2 S 3 ) x glasses with x = 0.005, 0.01, 0.02 and 0.04 at different conditions. Fine tuning of the annealing of the quenched glass as well as the mixing of nanocrystals in to the molten glass resulted glass-crystalline composites with different amounts and distribution of 20–50 nm large Bi 2 S 3 nanocrystals as well as larger, up to few micrometer long, needle-like crystals. Structural and optical investigations support the presence of the Bi 2 S 3 crystalline phase in all composites. Optical absorption and the photoconductivity of bulk composite samples follow the structural changes of the structure in the amorphous and amorphous-crystalline phase. In addition, the 290 cm −1 characteristic band in Raman spectra may be used for tracing the formation of the nanocomposites.