The vibrational properties of ferroelectric phase transitions of SrBiz(Nbx Tal.,)209 ceramic system (x=O, 1/3, 213, 1) have been studied by Raman spectroscopy in the temperature range from room temperature up to 5OU OC. For all composit~ons the lowest optical modes indicate the remarkable temperature dependerice towards T, arid disappear above T,. Their damping factors increase rapidly towards T, , while the softening of mode frequency is relatively small.The composition dependence of the rigidsublattice mode and the symmetric stretching mode of oxygen octahedra has been discussed.
The lattice instability related to ferroelectric phase transitions of Bi3TiNbOg and Bi3TiTa09 has been studied by Raman scattering in the temperature range between IOOK and 1250 K. The lowest optical mode of Bi3TiNb09 at 31 cm-', softens remarkably upon heating towards the Curie temperature T, = 1223 K. Similarly, the lowest optical mode of Bi3TiTaOg at 29cm-', also shows marked softening towards T, = 1143 K. The squared frequency changes linearly to temperature, and tends to zero at several hundred degrees above T,. The damping factor of these lowest modes increases markedly as their frequency decreases, and becomes overdamped at several hundred degrees below T,.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.