Optical Properties of Li Doped KTaO3 Using Spectroscopic Ellipsometer.

Measurements of complex refractive indices n* = n - iκ are performed on pure KTaO3 and K0.93Li0.07TaO3 single crystals by using a spectroscopic ellipsometer in temperature range from room temperature to 10 K. At room temperature, experimentally obtained complex dielectric constants ε* = ε1-iε2 of both crystals are analyzed by the classical Drude model. Temperature dependence of the imaginary part ε2 of K0.93Li0.07TaO3 shows a small but distinct change around 70 K. The origin of the anomalous behavior is discussed. [ABSTRACT FROM AUTHOR]