PIEZOELECTRIC RESONANCE IN KAP SINGLE-CRYSTALS

The frequency response of the dielectric constant (epsilon(r)), dielec tric loss (tan delta) and impedance (Z) of Potassium acid pthalate (KA P) single crystals, monitored along the polar axis, is characterised b y the presence of strong mechanical resonances, in the 50-200 kHz regi on. The observed resonance behaviour, which is dependent on the geomet ric size of the sample, is attributed to the piezoelectric nature of t he sample. Studies on the effect of variation of temperature and press ure, on the stiffness coefficient (C), indicate that C increases with increasing pressure and decreasing temperature. The electro-mechanical coupling coefficient (k) has been evaluated based on the resonance-an tiresonance method and its dependence on temperature and pressure has been studied.