Raman Scattering and Lattice-Dynamical Calculations of Crystalline KNO3

摘要

The Raman spectrum of a KNO3 single crystal was measured at both room and liquid-nitrogen temperatures. Lattice-dynamical calculations, based on the rigid-ion approximation and empirical potentials, were performed. The possibility of a phase transition at 217 K was investigated by measuring the temperature dependence of the Raman spectrum. The potassium nitrate crystal demonstrates strongly anharmonicity and dynamical disorder in its lattice-dynamical properties. Below 384 K, potassium nitrate is in so-called phase II. Above 403 K, it is designated in phase I. It has a ferroelectric phase (phase III) between 384 and 398 K. Balkanski, Teng, and Nusimovici reported Raman scattering at room and several higher temperatures.