High-performance Pb(Zr_1−xTi_x)O₃ (PZT) piezoceramics are urgently desired by the market in view of their expanded operating temperature range, reduced property temperature dependence, and 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)O₃ ternary piezoceramics; the modifying effects of La₂O₃ on this perovskite system were investigated in terms of the structures, electrical properties, and thermal depolarization behaviors of ceramics. The field-dependent dielectric and conduction properties indicated that there are close correlations among oxygen vacancies (V_O), 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 domains. The sample doped with 0.15 wt% of La₂O₃ shows excellent electrical properties with T_C = 387 ℃, d₃₃ = 332 pC/N, TK_ε = 5.81×10⁻³ ℃⁻¹, P_r = 20.66 μC/cm², T_d = 356 ℃. 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.

In this work, different amount of Cr₂O₃ (x = 0–0.3 wt%) as dopant were doped into the Aurivillius-type compound Bi_2.8Gd_0.2TiNbO₉ (BGTN), such a kind of Gd/Cr co-doped Bi₃TiNbO₉ ceramics with improved electrical properties were synthesized by the convenient solid-state reaction route. The substitution of Cr³⁺ for Ti⁴⁺ at B-site induced the lattice distortion of pseduo-perovskite layer. Fewer Cr₂O₃ dopant (x < 0.2) resulted in the grain refinement of ceramics. After Cr₂O₃ was added into BGTN, T_C decreased to the vicinity of 908 ℃. Below T_C, the relaxed dielectric response resulted from charge carriers hopping induced another board dielectric permittivity peak, whose starting temperature shifts toward lower side gradually with increase of x. The values of E_a^con calculated from the Arrhenius relationship between conductivity and temperature indicated the intrinsic conduction at high temperature is dominated by the long-range migration of doubly ionized oxygen vacancies. Moderate Cr₂O₃ dopant (x = 0.1–0.25) are conducive to the enhancement of piezoelectric property and thermal stability. The sample with x = 0.2 achieved both a high T_C~903 ℃ and a high d₃₃~18 pC/N at the same time. Also, its d₃₃ can retain 80% of the initial value after the sample was annealed at 800 ℃ for 4 h.