SOLID-STATE NMR-STUDIES OF 2 PHASES FOR TIN HEXATHIOHYPODIPHOSPHATE

Magic-angle spinning P-31 and Sn-119 NMR spectra of Sn2P2S6 are presen ted. Spectra were recorded at room temperature, 80-degrees-C, and 100- degrees-C. Two distinct center-band resonances are observed both for t he phosphorus and for the tin spectra at room temperature. When the te mperature is raised above the ferroelectric phase-transition temperatu re (T(c) approximately 70-degrees-C), both phosphorus and tin show sin gle center-band resonances. These results are generally consistent wit h earlier structural characterization. The spinning sideband patterns at both low and high temperatures were analyzed in order to determine the principal components of the shielding tensor. Consideration of the P-31 shielding tensor suggests that the point symmetry at the phospho rus site in the room-temperature phase is less than that implied by X- ray analysis.