Ferroelectric "Soft" Mode in KTaO3

Abstract
The far infrared reflectivity of KTaO3 has been studied as a function of temperature from 12 to 463°K. The results have been analyzed by means of a Kramers-Kronig method, and indicate a "soft" mode, lowering its frequency as the temperature is lowered towards the "Curie" temperature. This is in accordance with the temperature dependence of the dielectric constant interpreted through Cochran's theory.