Low-temperature Orthorhombic Structure Research Articles

Raman‐ and infrared measurements and the study of phase transitions in DyVO4

AbstractThe observed Raman and infrared active lattice vibrations of DyVO4 are calculated using a valence force field for the internal vibrations of the VO4 complexes and a central force field for the external vibrations. On this basis the degree of coupling between internal and external lattice modes is calculated and found to be small for most of the modes. In addition, the frequencies for the low temperature orthorhombic structure below 13.8 K are calculated by adopting a slightly modified force field with the appropriate symmetry. The effect of such an orthorhombic deformation is very small for the non‐degenerate frequencies but yields splittings of the degenerate frequencies of the order of 10 cm−1. These predictions are in agreement with the observations.