Thermal stability of nanoparticle size and phase composition of nanostructured Ag2S silver sulfide

Abstract

The thermal stability of phase composition and particle size of nanocrystalline silver sulfide Ag2S powder has been examined for the first time by in situ high-temperature X-ray diffraction, scanning electron microscopy and Raman spectroscopy methods. It was shown that in oxidizing environment or in the presence of oxidizing impurities, heating of nanostructured silver sulfide is accompanied by its decomposition (dissociation) with isolation of metallic silver. Reduction of silver sulfide particles leads to decreasing the decomposition temperature of Ag2S. The decomposition of Ag2S nanopowder with isolation of silver metal as a result of heating in air by high-power laser radiation was confirmed by Raman scattering. In the absence of oxidizing environment, heating of silver sulfide does not lead to its decomposition and nanoparticle growth up to the temperature of ∼450 K. The nanoparticle size increases as a result of annealing at a temperature of 450–930 K corresponding to the region of collective recrystallization of silver sulfide nanopowder. For nanostructured silver sulfide, the activation energy Q of collective recrystallization in the temperature range 450–900 K is ∼0.12 eV⋅atom−1.