Phase-formation, microstructure, and piezoelectric/dielectric properties of BiYO3-doped Pb(Zr0.53Ti0.47)O3 for piezoelectric energy harvesting devices

This paper proposes a method for the composition and synthesis of lead zirconate titanate (PZT) piezoelectric ceramic for use in energy harvesting systems. The proposed material consists of (1−x)Pb(Zr0.53Ti0.47)O3–xBiYO3 [PZT–BY(x)] (x=0, 0.01, 0.02, 0.03, 0.04, and 0.05 mol) ceramics near the morphotropic phase boundary (MPB) region, prepared by a solid-state mixed-oxide method. The optimum sintering temperature was found to be 1160 °C, which produced high relative density for all specimens (96% of the theoretical density). Second phases were found to precipitate in the composition containing x≥0.01 mol of BY. It is shown that the addition of BY inhibits grain growth, and exhibits a denser and finer microstructure than those in the un-doped state. Fracture surface observation revealed predominant intergranular fracture for x=0 and x=0.01, while a mixed mode of transgranular and intergranular fracture appeared for x≥0.02. The optimal doping level was found to be x=0.01, for which a dielectric constant (K33T) of 750, a Curie temperature (TC) of 373 °C, a remnant polarization (Pr) of 50 µC/cm2, a piezoelectric constant (d33) of 350 pC/N, and an electro-mechanical coupling factor (kp) of 65% were obtained. In addition, the piezoelectric voltage constant (g33), and transduction coefficient (d33×g33) of PZT–BY(x) ceramics have been calculated. The ceramic PZT–BY(0.01) shows a considerably lower K33T value, but higher d33 and kp. Therefore, the maximum transduction coefficient (d33×g33) of 18,549×10−15 m2/N was obtained for PZT–BY(0.01). The large (d33×g33) indicates that the PZT–BY(0.01) ceramic is a good candidate material for energy harvesting devices.