Optimized conditions for fabrication of La-dopant in PZT ceramics

The ferroelectric Pb(ZrxTi1 − x)O3 ceramics are well known as piezoelectric materials for electro-mechanical transducers. The highest piezoelectric coupling coefficients as well as maximum permittivity are located near the morphotropic phase boundary (MPB). The region of phase transition between the tetragonal and rhombohedral structures in the Pb(ZrxTi1 − x)O3 ceramic shows very adaptable piezoelectric characteristics due to the phase coexistence phenomena and exhibits a sensitivity of properties to the preparation method, the composition, the firing temperatures and the kinds of additives. The purpose of this research is to determine the optimum condition and the effect of doping La into Pb(Zr0.52Ti0.48)O3 ceramics prepared by solid state reaction. The properties, such as microstructure, physical properties, dielectric constant (ɛr) and piezoelectric properties (kp and Qm) of undoped and lanthanum-doped PZT ceramics were investigated. Several effects, such as firing temperature, grain size and dopant content on structure and properties of PZT have also studied. The undoped PZT ceramics with Zr/Ti at 52/48 indicated the highest ɛr = 1101 (sintering for 1 h) and kp = 0.39 (sintering for 2 h). Doping with lanthanum ion led to an improvement in the ɛr but a reduced Qm value. The optimum values of kp is found to be 0.48 for PLZT (1/52/48) doped with 1.00 mol% La3+ and sintered at 1200 °C for 1 h.