Effects of Nb ₂O ₅ addition on the microstructure, electrical, and mechanical properties of PZT/ZnO nanowhisker piezoelectric composites

Nb ₂O ₅-modified PZT/ZnO nanowhisker (denoted as PZT/ZnO _w-Nb ₂O ₅) piezoelectric composites were prepared by a solid state sintering technique. Effects of Nb ₂O ₅ addition on the microstructure, electrical, and mechanical properties of the PZT/ZnO _w composites were investigated. With increasing Nb ₂O ₅ content, the grain size of the composites was reduced and the fracture mode changed from intergranular to intragranular gradually. Compared with the PZT/ZnO _w composites, the dielectric, piezoelectric, and ferroelectric properties of the PZT/ZnO _w-Nb ₂O ₅ composites were improved significantly, while mechanical properties were enhanced slightly. The optimum electrical and mechanical properties were achieved for the PZT/ZnO _w composites modified with 0.75 wt% Nb ₂O ₅ sintered at 1150 °C, with dielectric permittivity ε _r, piezoelectric coefficient d ₃₃, planar electromechanical coupling k _p, remnant polarization P _r, fracture toughness K _IC, and flexural strength σ _f being on the order of 4930, 600 pC/N, 0.63, 29.2 μC/cm ², 1.56 MPa m ^1/2 and 130 MPa, respectively. The Nb ₂O ₅-modified PZT/ZnO _w piezoelectric composites, with comparable electrical properties and improved mechanical properties than those of commercial PZT-5H ceramics, are promising candidates for further applications.