MOSSBAUER STUDY OF SNO LATTICE-DYNAMICS

Lattice dynamics of tin monoxide was investigated by Mossbauer spectro scopy in the range 16-294 K. From the temperature dependence of the ab solute recoil-free fraction, f(T), the second moment of the phonon spe ctrum and the anharmonic constant epsilon(-2) were determined. These r esults suggest that the dominant anharmonic contribution arises from t he cubic term of the vibrational phonon-phonon coupling Hamiltonian. T he absolute recoilless fraction was determined at room temperature by the linewidth method and found to be f(295 K) = 0.12(1). No phase tran sitions were observed in this temperature range. The Mossbauer-line in tensity-ratio-data temperature dependence displays a likely vibrationa l anisotropy.