RESEARCH ON HIGH POWER TRANSDUCER CERAMICS. STRESS SENSITIVITY OF PIEZOELECTRIC CERAMICS. PART THREE: SENSITIVITY TO COMPRESSIVE STRESS PERPENDICULAR TO THE POLAR AXIS

Measurements are reported of the change in permeability, loss, and the piezoelectric constants, d31 and d32 for piezoelectric ceramic transducer materials subjected to high stress perpendicular to the polar axis (T1). Ceramics useful for high power applications (PZT-4 and PZT-8) and some donor-doped ceramics of high sensitivity but with high losses that make such applications unwise (PZT-5A and PZT-5H) were tested. Permeability generally decreased with stress, T1, opposite to results with parallel stress, T3. The piezoelectric coefficient d31 (in the direction of stress application) decreases markedly with stress, while d32 (in the direction perpendicular to the stress and the polarization) generally rises. The effects are less severe for the 'hard' ceramics. A permanent change in pseudo crystal symmetry from infinity m to 2mm is observed for the donor-doped ceramics, even at relatively low stress levels (5 kpsi). (Author) See also Part 2, AD-814 956.