Displacive-type phase transition in LiTaO3and LiNbO3

Abstract
The analysis of the temperature dependence of far-infrared reflection spectra allowed us to explain the mechanism which drives the ferroelectric (FE)-paraelectric (PE) phase transition in LiTaO3 (Tc ∼ 890 K) and LiNbO3 (Tc ∼ 1480 K).