• solid state;
  • phase transitions;
  • molybdates;
  • orthorhombic structure


Polarized Raman spectra of a single crystal of gadolinium molybdate, Gd2(MoO4)3 were obtained between 400 and 80 K. Tentative assignments of high-wavenumber bands of symmetric and antisymmetric MoO4 stretching modes to the three types of tetrahedra present in the ferroelectric phase described by the C2v8 space group are made on the oriented gas model. A careful analysis of the low-wavenumber spectra allowed identification of new bands compared to those in the literature. The evolution of wavenumbers in the investigated temperature range indicates that a small structural change takes place at about 200 K. Some modes soften when approaching the ferroelectric–paraelectric transition at 159 °C. Copyright © 2006 John Wiley & Sons, Ltd.