COMPARISON OF MECHANICAL AND ELECTRICAL PROPERTIES OF PIEZOELECTRIC COMPOSITES PZT/ZnO AND PZT/Al FABRICATED BY POWDER METALLURGY

Lead zirconate titanate (PZT) as a piezoelectric ceramic has been used widely in the fields of electronics, biomedical engineering, mechatronics and thermoelectric. Although, the electrical properties of PZT ceramics is a major considerable, but the mechanical properties such as fracture strength and toughness should be improved for many applications. In this study, lead monoxide, zirconium dioxide and titanium dioxide were used to synthesize PZT compound with chemical formula Pb(Zr 0.52 ,Ti 0.48 )O 3 by calcination heat treatment. Planetary mill with zirconia balls were used for homogenization of materials. Two-stage calcination was performed at temperatures of 600˚C and 850˚C for holding time of 2h. In order to improve the mechanical properties of PZT, various amount of ZnO and/or Al 2 O 3 particles were added to calcined materials and so PZT/ZnO, PZT/Al 2 O 3 and PZT/ZnO+Al 2 O 3 composites were fabricated. Composites samples were sintered at 1100˚C for 2 h in the normal atmosphere. Microstructural component and phase composition were analyzed by XRD and SEM. The density, fracture strength, toughness and hardness were measured by Archimedes method, three-point bending, direct measurement length crack and Vickers method, respectively. Dielectric and piezoelectric properties of the samples were also measured by LCR meter and d33metet tester, respectively. The results showed that by addition of ZnO and Al 2 O 3 to composite materials, the relative density of PZT based composites was increased in conjunction with a signification improvement of mechanical properties such as flexural strength, toughness and hardness. Moreover, the dielectric and piezoelectric properties of PZT such as dielectric constant, piezoelectric coefficient and coupling factor were decreased while the loss tangent was also increased.