Brillouin spectroscopic evidence for a relaxation mode in ferroelectric PbHPO4 and PbDPO4

M. H. Kuok, S. C. Ng, and D. J. Lockwood
Phys. Rev. B 51, 8005 – Published 1 April 1995
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Abstract

Brillouin spectra of ferroelectric PbHPO4 (Tc=310 K) and its deuterated isomorph PbDPO4 (Tc=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 Tc. The relaxation times, τ0, for a noninteracting dipole are evaluated from the Brillouin shifts, based on a phenomenological approach. The τ0 values are the same in both PbHPO4 and PbDPO4, 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

Authors & Affiliations

M. H. Kuok and S. C. Ng

  • Department of Physics, National University of Singapore, Singapore 0511, Republic of Singapore

D. J. Lockwood

  • Institute for Microstructural Sciences, National Research Council, Ottawa, Ontario, Canada K1A 0R6

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Vol. 51, Iss. 13 — 1 April 1995

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