(KLT) Ferroelectric Relaxor Crystals using Resonant Ultrasound Spectroscopy*

Potassium Lithium Tantalum Oxide (KLT), although it is a very under-investigated material, represents a relatively simple model for relaxor ferroelectricity phenomenon. Moreover, it is optically transparent that makes it suitable for applications of adaptive optic devices. Temperature-dependent Resonant Ultrasound Spectroscopy (RUS) is a quick and nondestructive method to characterize elastic properties of materials, which makes it a useful for studying relaxor ferroelectrics. The sample is suspended between the excitation and receiving transducers. By transmitting and scanning the excitation frequencies, one can record a resonance spectrum of the sample to be able to determine a set of elastic constants of the sample through mathematical modelling. We report the results of our study of temperature dependence of the c₁₁ elastic stiffness tensor constant for the KLT crystal with x=0.1 at a range of temperatures from 300K down to 65K. Anomalous softening of the c₁₁ elastic constant reveal the critical temperature range of T_c at which the phase transition occurs.