Stress Sensitivity of Piezoelectric Ceramics: Part 3. Sensitivity to Compressive Stress Perpendicular to the Polar Axis

Measurements are reported of the change in permittivity, 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. Permittivity generally decreased with stress, T1, opposite to results with parallel stress, T3. The piezo-electric 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 pseudocrystal symmetry from ∝ m to 2mm is observed for the donor-doped ceramics, even at relatively low stress levels (5 kpsi).