Attaining excellent piezoelectric properties and thermal stability in PIN-PHT ceramics by integrating tetragonal phase and relaxor ferroelectrics

Herein, Nd₂O₃-doped 0.11PIN-0.89PHT (PIN-PHT) single-phase tetragonal piezoelectric ceramics are prepared by traditional solid-phase method. In addition, impacts of Nd-doping on crystal structure and electrical performance for 0.11PIN-0.89PHT ceramics are systematically investigated. Based on Landau theory, we propose a novel strategy for obtaining high-performance ceramics by combining tetragonal phase and relaxor ferroelectrics. Results reveal that the introduction of polar nano-regions in tetragonal phase ceramics by doping with rare-earth ions to convert normal ferroelectrics into relaxed ferroelectrics is responsible for excellent properties of 0.11PIN-0.89PHT-xNd ceramics. The optimized comprehensive performance is obtained at x = 0.9 mol%, where d₃₃ = 670 pC/N, S_max = 0.29% (45 kV/cm), strain hysteresis = 8.68% (45 kV/cm), d₃₃* = 736 p.m./V (30 kV/cm), T_C = 312.6 °C, ε_r = 3234, k_p = 0.62, tanδ = 0.014, and excellent high-temperature stability in temperature range of 20–240 °C. After 10⁶ cycles, electrical properties and strain remain unchanged, showing excellent anti-fatigue behavior. This work provides a novel approach for the development of ceramics with outstanding piezoelectric response, high strain, low strain hysteresis, excellent anti-fatigue resistance and thermal stability, and is expected to realize practical applications of piezoelectric ceramics.