Temperature dependence of the polarization, dielectric constant, damping constant and the relaxation time close to the ferroelectric-paraelectric phase transition in LiNbO3

Kiraci A., YURTSEVEN H. H.

OPTIK, vol.132, pp.183-191, 2017 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 132
  • Publication Date: 2017
  • Doi Number: 10.1016/j.ijleo.2016.12.020
  • Journal Name: OPTIK
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.183-191
  • Keywords: Mean field theory, Order parameter, Dielectric susceptibility, Damping constant, Relaxation time, LiNbO3, LITHIUM-NIOBATE, RAMAN-SCATTERING, OPTICAL PHONONS, MOLECULAR-DYNAMICS, BARIUM-TITANATE, MODE, LITAO3, FREQUENCY, TANTALATE, CRYSTALS
  • Middle East Technical University Affiliated: Yes

Abstract

We calculate the order parameter (spontaneous polarization) and the inverse dielectric susceptibility at various temperatures in the ferroelectric phase of LiNbO3 for its ferroelectric-paraelectric phase transition (T-C =1260 K) using the Landau phenomenological model. For this calculation, the Raman frequencies of the soft optic mode (TO1) are used as the order parameter and the fitting procedure is employed for both the order parameter and the inverse dielectric susceptibility by means of the observed data from the literature. The temperature dependences of the damping constant and the inverse relaxation time are also computed using the pseudospin-phonon coupled model and the energy fluctuation model for the ferroelectric phase of LiNbO3. The activation energy is deduced from the damping constant for both models studied and compared with the k(B)T(C) value of LiNbO3.