Abstract
Raman scattering and infrared absorption studies of ferroelectric SbNb, antiferroelectric BiNb, and the solid solution for in the range 20-1200 are reported. These are the first vibrational spectroscopic investigations in these stibiotantalite-type systems. Symmetry assignments are proposed for the internal modes. Such an assignment is shown to lead to a consistent set of values for the local force constants calculated under the general quadratic valence force field. The nature of the variations of lattice and internal frequencies with changes in -ion concentration is qualitatively discussed with particular reference to the ferroelectric soft mode.
- Received 23 May 1986
DOI:https://doi.org/10.1103/PhysRevB.34.8137
©1986 American Physical Society