Local lattice distortion drives enhanced piezoelectricity and thermal stability in 0.9Pb(Yb,Nb)O₃–0.1Pb(Hf,Ti)O₃ ceramics

Reversible domain switching is a common method for enhancing piezoelectric response. However, low-energy-barrier domain switching simultaneously exacerbates temperature-sensitive phase transitions. This establishes an inverse correlation between "high piezoelectricity and low T_C" in conventional systems. It is imperative to break the inherent compromise between piezoelectric response and thermal stability in lead-based ceramics. This study presents a breakthrough in addressing this longstanding issue via atomic-level lattice engineering in Pb(Yb,Nb)O₃–Pb(Hf,Ti)O₃ systems. A comprehensive investigation, combining advanced characterization techniques and density functional theory (DFT) calculations, elucidates the atomic-scale mechanisms underlying the performance enhancement. The co-doping strategy generates localized heterogeneous regions, primarily manifested distortions at oxygen octahedral sites, which effectively lower the crystal symmetry and facilitate enhanced polarization switching. Our approach achieved a piezoelectric coefficient reaching 592 pC/N in the ceramic, while maintaining excellent thermal characteristics (Curie temperature of 343.1 °C) and a dielectric loss (Tan δ) of 0.0121. Compared with the benchmark material (d₃₃ = 458 pC/N, Tc = 351.8 °C), PYN-PHT-0.8(Li⁺+Mo⁶⁺) represents a 30 % enhancement in d₃₃ and only a 2.5 % decrease (8.7 °C shift) in Tc. Through precise control of local Landau potential energy landscapes at dopant sites, the material demonstrates exceptional thermal stability, maintaining a small fluctuation range (△d₃₃ ∼ 4.7 %) across a broad temperature range (ambient temperature-300 °C). The findings provide critical insights into providing crucial guidance for designing advanced piezoelectric materials with comprehensive performance.