RESEARCH ON HIGH POWER TRANSDUCER CERAMICS. STRESS SENSITIVITY OF PIEZOELECTRIC CERAMICS. PART FOUR: COMPARISON OF PB(ZR, TI)O3 COMPOSITIONS ON EITHER SIDE OF THE PHOMBOHEDRAL-TETRAGONAL PHASE BOUNDARY.
PST-4 and its equivalents form a good base from which to proceed with development of transducer ceramics that are less stress sensitive. A simple first step is to change the ZrTi ratio and measure stress sensitivity for different compositions. Ceramics far into the tetragonal field 4T, well into the rhombohedral field 4R, and very close to the phase boundary 4 phi were prepared and tested. Compared with PZT-4 the 4T composition showed superior stability of permittivity and d33 with mechanical compression parallel to the poling direction T3. Both 4R and 4T behave as hard ceramics, i.e. very high compressive stresses are required to degrade permanently these materials. However, variations of properties with stress are high for 4R. Depolarization due to mechanical stress is severe with 4 phi. Author