Low-temperature vibrational properties of KGd(WO4)2: (Er, Yb) single crystals studied by Raman spectroscopy

Temperature-dependent polarized Raman spectra of KGd(WO4)2: (Er, Yb) single crystals have been analyzed over the 77–292 K temperature range. The Ag and Bg spectra obtained are discussed in terms of factor group analysis. The spectra have been found to reveal the bands related to internal and external vibrations of WO42−, WOW and WOOW molecular groups. Strong depolarization of the majority of the Raman bands has been observed in the whole temperature range. Some anomalies in the spectral parameters of selected Raman bands below 175 K have been discussed in terms of the local distortion of WO42− ions in KGd(WO4)2: (Er, Yb) crystals.