Room-temperature synthesis of Sn2P2S6

Twenty-nanometer particles of Sn2P2S6 are prepared at room temperature (RT) via a metathesis reaction in aqueous media. Mossbauer and Raman spectroscopy and X-ray diffraction characterization of these powders accord with data on Sn2P2S6 synthesized at high temperature (HT). The phase transition and second harmonic generation known to exist in the HT form were not detected in the RT variant, suggesting a critical particle size >20 nm for the occurrence of polar order in Sn2P2S6. It is argued that thermal enhancement of the metathesis reaction and growth kinetics should lead to larger, ferroelectric Sn2P2S6 crystallites. (C) 1997 Academic Press.