Preparation and phase control of nanocrystalline silver indium sulfides via a hydrothermal route

A hydrothermal route was proposed to prepare and control nanocrystalline si lver indium sulfides (orthorhombic AaInS(2), tetragonal AgInS2, and cubic A gIn5S8). The reaction was carried out in an autoclave in the temperature ra nge of 100-280 degreesC with AgCl, InCl3, and thiourea as reactants. X-ray powder diffraction patterns and transmission electron microscopy images sho wed that the products were AgInS2 and AgIn5S8 phases and well crystallized with grain diameter in the range of 20-70 nm. X-ray photoelectron spectra o f the single AgIn5S8 phase revealed the surface stoichiometry (AgIn5.05S8.1 1), and its room temperature Raman spectrum showed a strong peak at 130 cm( -1) and a weak peak at around 290 cm(-1). The influence of reaction tempera ture on the phases in the final products was investigated. A possible react ion mechanism of the formation of silver indium sulfides was also briefly d iscussed.