Abstract: Maintaining high piezoelectric response and piezoelectric temperature stability of lead-based piezoceramics is critical for applications under high-temperature environments. Unfortunately, the piezoelectric response of lead-based piezoceramics shows strong temperature dependence. Herein, an innovative strategy was proposed to solve this problem. The method consisted of constructing “slush-like” polar states by introducing localized heterostructures in the tetragonal phase structure to lower the energy barriers. The presence of the tetragonal phase stabilized the domain structure, providing excellent temperature stability, while the localized heterostructures also flattened the free energy landscape and enhanced the piezoelectric response. The strategy was implemented by using 0.11Pb(In_0.5Nb_0.5)O₃-0.89Pb(Hf_0.47Ti_0.53)O₃(PIN-PHT) piezoceramics doped with heterovalent ion Nb⁵⁺ to form a “slush-like” polar state with strong interactions inside the ceramics. The piezoelectric response and relaxor behavior of the ceramics were then investigated using piezoelectric force microscopy to reveal the mapping relationship between the complex ferroelectric domain structure and both the piezoelectric response and temperature stability. At Nb⁵⁺ doping amount of 0.8 mol %, the ceramics showed excellent comprehensive performances with d₃₃ = 764 pC/N, T_c = 319.1 °C, εr = 3253.59, k_p = 0.67, and tanδ = 0.0122. At an external ambient temperature of 300 °C, the d₃₃ of PIN-PHT-0.8Nb⁵⁺ remained high at 734 pC/N, with piezoelectric performance retention of 96.1 %, showing excellent temperature stability. Overall, a new path was proposed for developing Pb-based piezoceramics with both good piezoelectric response and high-temperature stability, promising to broaden the temperature range of high-temperature piezoceramics for various applications.

Key words: Gibbs free energy, “slush-like”polar states, Giant piezoelectric response, High-temperature stability