Raman and x-ray diffraction studies of nanometric Sn2P2S6crystals

Nanometric Sn2P2S6 crystalline powders and ceramics are studied by x-ray diffraction and Raman spectroscopy. The average crystallite size is estimated from TEM and x-ray data. The observed features in the Raman spectra are discussed in view of confinement-related selection rules relaxation, surface phonon modes and possible partial substitution of sulfur by oxygen at the nanometric powder surface.