Acceptor doping enhanced defect effects on the electrical properties of PZST antiferroelectric ceramics

Chemical doping is a key approach to tailoring the properties of PbZrO₃-based antiferroelectric materials. However, defects introduced during aliovalent doping can sometimes play a decisive role in regulating material properties. Here, we systematically investigate the effects of doping with Gd³⁺, Ba²⁺, and K⁺ ions on the phase structure and physical properties of Pb[(Zr_0.7Sn_0.3)_0.94Ti_0.06]O₃ (PZST94/6). Gd³⁺ doping enhances antiferroelectricity, while Ba²⁺ doping enhances ferroelectricity, consistent with predictions based on tolerance factor and electronegativity. In contrast, doping with large-radius K⁺ ions contradicts the above predictions and unexpectedly stabilizes the antiferroelectric phase. The mechanism involves a significant increase in oxygen vacancy concentration upon K⁺ doping, which leads to the formation of defect dipoles. The local internal electric field generated by these dipoles interferes with polarization switching, ultimately raising the phase transition electric field while lowering both remanent and maximum polarizations in PZST94/6 ceramics. This work demonstrates that defect engineering can override conventional predictions based on ionic radius and electronegativity parameters, thereby offering a novel strategy for designing high-performance antiferroelectric materials.