Temperature-dependent Raman scattering spectra of CsBi(MoO4)(2)

Successive phase transitions in CsBi(MoO4)(2) at 125 and 325 K have been st udied by Raman spectroscopy. The changes in the crystal structure, induced by the low-temperature first-order transition, have been discussed. The fou nd anomalous shifts of some internal modes towards lower frequency with dec reasing temperature have been explained as a result of strengthening of [GRAPHICS] double or single [GRAPHICS] oxygen bridges. The present results also provide information on the origin of the unknown phase, identified recently in CsDy(MoO4)(2). (C) 2000 Elsevi er Science Ltd. All rights reserved.