La ₂O ₃-modified BiYbO ₃–Pb(Zr,Ti)O ₃ ternary piezoelectric ceramics with enhanced electrical properties and thermal depolarization temperature

Abstract

High-performance PZT piezoceramics are urgently desired by the market in view of their expanded operating temperature range, reduced properties temperature dependence, enhanced sensitivity and acoustic power. In this work, we reported a kind of low-cost and high-performance 0.06BiYbO₃‒0.94Pb(Zr_0.48Ti_0.52)O₃ternary piezoceramics, the modifying effects of La₂O₃ on this perovskite system were investigated in terms of the structures, electrical properties and thermal depolarization behavior of ceramics. The field dependent dielectric and conduction properties indicated that there are close correlations among oxygen vacancies, conducting electrons, and intrinsic conduction process. The degradation in ferroelectric properties observed in those samples doped with more than 0.15 wt.% of La₂O₃ indicated that the occupying mechanisms of La³⁺ changed from the donor substitution for Pb²⁺ to the isovalent substitution for Bi³⁺. The thermally-depoling micromechanisms of ceramics were revealed from the thermodynamic processes of defect dipoles and intrinsic dipoles within ferroelectric domians. The sample doped with 0.15 wt.% of La₂O₃shows excellent electrical properties, including T_C=387 °C, d₃₃=332 pC/N, Tk_ε=5.86×10^-3/℃, P_r=21 μC/cm², and T_d=356 °C. The significantly enhanced electrical properties and thermal depolarization temperature benefited from the donor substitution of La³⁺decreasing the oxygen vacancy concentration in the lattice and possibly optimizing the ferroelectric domain structure of ceramics.