Temperature-dependent Raman scattering study on Cs4W11O35 and Rb4W11O35 systems

In this work we report results of Raman scattering study on Cs4W11O35 and Rb4W11O35 in the 30–295 K temperature range. Changes in the Raman spectra indicated presence of two structural phase transformations in the Cs4W11O35 (Rb4W11O35) system taking place at 110 K (100 K) and 165 K (210 K). These transformations lead to symmetry increase on cooling. Temperature dependence of Raman linewidths indicated larger contribution of an orientational mechanism in Cs4W11O35 than in the Rb4W11O35 system. No soft-like mode was observed that could point to a displacive type behavior at the phase transitions. Additional Raman scattering measurements were performed on the Cs4W11O35 system in the 300–820 K range. No temperature-induced phase transitions were observed for this system above room temperature.