Thermal and electromechanical performance in BaSnO3-modified potassium sodium niobate piezoceramics via two-step sintering

In view of industrial applications requiring high piezoelectric activity, KNN-based ceramics face two key constraints: insufficient density and temperature sensitivity. To address these challenges, this study first introduces BaSnO3 and employs two-step sintering method (TSS) for fabrication, thereby synthesizing ternary 0.975K(0.5)Na(0.5)NbO(3)-0.025Bi(0.5)K(0.5)TiO(3)-xBaSnO(3) (KNN-1000xBaSn; x = 0, 0.3 %, 0.6 % and 0.9 %) with superior piezoelectricity (d(33) = 217-257 pC/N; d(33)* = 265-330 pm/V; S = 0.16-0.21 %), high Curie temperature (T-C = 325-349 degrees C) and densification (4.3-4.5 g/cm(3); relatively density similar to 96 %). In one respect, the TSS allows minimal volatilization of alkali metals while promoting grain homogenization. In another respect, the introduction of BaSnO3 enhances the mobility of domain walls, meanwhile fosters diffuse phase transitions (DPT) and widens dielectric peaks without significantly impairing T-C. Moreover, the KNN-6BaSn obtain not only reinforced d(33) (256 pC/N) with high T-C (325 degrees C) and epsilon ' (1016), but also fatigue resistance and extreme-temperature endurance with excellent d(33)* (445 pm/V at 90 degrees C; 300 pm/V at 180 degrees C). This work provides a resultful dual-strategy for the emergence of lead-free piezoelectric products.