Order–disorder transition in the ferroelectric LiTaO₃

Abstract

The temperature dependences of the damping constant and the relaxation time are calculated by using the Raman frequencies of a* and the lowest A₁ (TO) phonons in the ferroelectric phase close to the ferroelectric-paraelectric transition in LiTaO₃ (T_C = 963 K). Both calculations are performed by considering the frequency as an order parameter for the pseudospin–phonon (PS) and the energy fluctuation (EF) models using the observed data from the literature. Values of the activation energies of this crystal are also deduced by using both models in this crystal. Our results show that the PS and EF models can describe the observed behavior adequately for the order–disorder transition in LiTaO₃.

Keywords:

• Damping constant
• relaxation time
• activation energy
• order–disorder transition
• LiTaO₃