Modifying the high-temperature dielectric properties of PLZT antiferroelectric ceramics by donor‒acceptor codoping

(Pb,La)(Zr,Ti)O₃ antiferroelectric (AFE) ceramics have attracted considerable interest due to their high-energy storage density and numerous field-induced phase transitions. However, the positional equilibrium of the A-site and B-site is typically maintained without considering that heterovalent doping of La³⁺ can induce defects within the material, leading to high-temperature leakage conduction. In this work, we introduced the acceptor ion Na⁺ at the A-site simultaneously and designed Pb_{0.9175–0.5x}La_0.055Na_xZr_0.975Ti_0.025O₃ (x = 0.01, 0.03, 0.055, 0.07, 0.10) AFE ceramics. The dielectric properties of these ceramics exhibited a consistent pattern of improvement followed by deterioration as the content of Na⁺ increased. Notably, when x = 0.055 (Na5.5), the AFE ceramic demonstrated superior high-temperature frequency stability with negligible leakage conduction. Impedance spectroscopy analysis suggested that Na5.5 displays the greatest resistance and highest E_dc. Concurrently, the thermally stimulated depolarization current indicates that Na5.5 possesses the lowest defect concentration and the largest E_a. This can be attributed to the internal generation of defect dipole clusters ($V_{\mathrm{Pb}}^{\prime \prime }-V_O^{••}-{\mathrm{Na}}_{\mathrm{Pb}}^{\prime }-{\mathrm{La}}_{\mathrm{Pb}}^{•}$), which effectively restrict the movement of charged defects. These findings suggest that Na5.5 holds significant potential for application and offer insights into the understanding of internal defects in lead-based AFE materials.