EFFECTS OF APPLIED ELECTRICAL-FIELD ON PIEZOELECTRIC PROPERTY AND COMPRESSIVE STRENGTH OF PZT

Variations of piezoelectric properties and compressive strengths of PZ T ceramics with the strength and the direction of poling were investig ated. With increasing the applied electric held, the coupling constant , k(33), increased constantly and the volume fraction of grain boundar y fracture also increased. This suggests that the rearrangement and th e anisotropic stretching of domains during the poling process led to w eakening the grain boundaries. Anisotropical compressive and tensile i nternal stresses of 137 MPa and 76 MPa were induced perpendicular and parallel to the poling direction, respectively. The isotropic compress ive strength of 52 MPa was found in the unpoled PZT specimens. The cha nge of internal stress of poled PZT by electrical field was coincident with that of compressive strength. The compressive strength of the sp ecimen revealed to be higher in parallel to the poling direction, but the internal stress in parallel to the poling direction was smaller th an the internal stress in perpendicular.