Lattice Dynamics and Temperature Dependence of the Linewidth of the First-Order Raman Spectra for Sintered Hexagonal GeO 2 Crystalline

The first-order Raman spectra of internal A1 and external modes in sintered hexagonal GeO 2 crystalline were measured in the temperature range of 293–873 K and the linewidths at these temperatures were obtained. The temperature dependence of the linewidths was analyzed using the phonon dispersion curves calculated on the basis of a rigid-ion model, and the results showed that it was caused approximately by the cubic anharmonic term in the crystal potential energy.