Structural Phase Transitions In Loparite-(Ce): Evidences From Raman Light Scattering

Raman spectroscopic studies of loparite-(Ce), a mineral of the perovskite family, are presented. Polarized Raman spectra were obtained in the temperature range of 50-300K. As analysis of the behavior of Raman modes showed, the temperature dependences of wavenumber, damping and intensity of the optical modes exhibited anomalies near 220 and 150K. Softening of the low-wavenumber modes observed in the vicinity of 150K is interpreted as an evidence of a ferroelectric phase transition. An anisotropic quasielastic light scattering in the low-wavenumber region of the Raman spectra was observed from 300 to 150K. As the data suggest, loparite-(Ce) has two structural phase transitions, one of which (at 150K) is a ferroelectric transition of the order-disorder type. Copyright (c) 2014 John Wiley & Sons, Ltd.