Estimation of Thickness of Ferroelectric Inversion Layers in LiTaO3 Plates by Measuring Piezoelectric Responses

A ferroelectric inversion layer can be formed in LiTaO3 by proton exchange in benzoic acid melts followed by heat treatment at temperatures just below the Curie point. This paper presents a method of nondestructively estimating the thickness of the inversion layer by measuring the piezoelectric responses associated with the thickness modes of vibration. It is demonstrated that the estimated values of inversion layer thickness agree well with those measured by microscope observation of etched cross sections of LiTaO3 plates.