Investigation of piezoelectric properties of crystals using surface excitation of ultrasonic waves and some results for ferroelectric triglycine sulphate

The surface excitation of ultrasonic waves as a new method of investigation of piezoelectric properties of materials is suggested and experimental results specified to theZ-direction of a single crystal of triglycine sulphate (TGS) are reported. It has been found that the piezoelectric stress constant e₂₃ of TGS depends on temperatureθ as:e ₂₃=K ₂₃(θ_c?θ)^?1 whereK ₂₃=(31±0.5) As m^?2 deg andθ _c=49.6°C. The influence of an externally applied d.c. electric field has been studied in order to account for a residual excitation of ultrasonic waves in TGS at temperatures above the Curie point.