Preparation and characterization of PZT wafers

Piezoelectric materials have recently attracted a lot of attention for ultrasonic structural health monitoring (shm) in aerospace, defence and civilian sectors, where they can act as both actuators and sensors. Incidentally, piezoelectric materials in the form of wafers (pwas-piezoelectric wafer active sensor, approx. 5-10 mm square and 0.2-0.3 mm thickness) are inexpensive, non intrusive and non-resonant wide band devices that can be surface-mounted on existing structures, inserted between the layers of lap joints or embedded inside composite materials. The material of choice for piezoelectric wafers is lead zirconate titanate (PZT) of composition close to morphotropic phase boundary [pb (zr(0.52) ti(0.48)) O-3]. However, an excess pbo is normally added to pzt as a densification aid and also to make up for the lead loss during high temperature sintering. Hence, it is of paramount importance to know how the shift of the lead content from the morphotropic composition affects the piezoelectric and mechanical properties of the sintered wafers, keeping in view the importance of mechanical properties of wafers in shm. In the present study, we observed that with the increase in the lead content of the sintered wafers, the dielectric and piezoelectric constants decreased. However, the elastic modulus, hardness and fracture toughness of the wafers increased with increasing lead content in the composition. Hence, the lead content in the sintered wafers should be optimized to get acceptable piezoelectric and mechanica