Effect of Sb-induced oxygen octahedral distortion on piezoelectric performance and thermal stability of Pb(In,Nb)O₃-Pb(Hf,Ti)O₃ ceramics

The combination of excellent thermal stability and outstanding electrical performance is of great significance for piezoelectric ceramics. Herein, we have prepared 0.11Pb(In_0.5Nb_0.5)O₃-0.89Pb(Hf_0.47Ti_0.53)O₃-Sb₂O₅ (PIN-PHT-xSb) ceramics by solid-phase method and investigated the effect of oxygen octahedral lattice distortion on microstructure and macroscopic electrical properties. The distortion index of oxygen octahedra is studied by Rietveld refinement, showing that optimal octahedral distortion can soften B-O repulsion, disrupt long-range ordered ferroelectric domains, and enhance local heterogeneities, significantly increasing piezoelectric properties. Moreover, outstanding thermal stability and ultrahigh piezoelectric response of PIN-PHT-1.2Sb ceramics are realized under the synergistic influence of octahedral distortion, excellent density, and large grain size. Compared with PIN-PHT ceramics, PIN-PHT-1.2Sb ceramics exhibit ultrahigh piezoelectric responses (d₃₃ = 706 pC/N, k_p = 0.68, ε_r = 3244), a high Curie temperature (T_C) of 300 °C, excellent thermal stability, and anti-fatigue properties.