Abstract
Brillouin spectra of ferroelectric (=310 K) and its deuterated isomorph (=462 K) have been measured as a function of temperature across their transition temperatures. Certain longitudinal acoustic waves are found to exhibit anomalous propagation in the vicinity of . The relaxation times, , for a noninteracting dipole are evaluated from the Brillouin shifts, based on a phenomenological approach. The values are the same in both and , indicating that the ferroelectric transition is driven by an order-disorder relaxation mode. This study also reveals that the paraelectric phase symmetry is, on a macroscopic scale, centrosymmetric.
- Received 24 October 1994
DOI:https://doi.org/10.1103/PhysRevB.51.8005
©1995 American Physical Society