Piezoelectric property amplification in 0.46PNN-0.23PIN-0.31PT ceramics via optimized low-temperature sintering and defect chemistry

The sintering temperature of piezoelectric ceramics plays a pivotal role in their cost and efficacy within the realm of multilayer actuator applications. While being conducive to piezoelectric capabilities of ceramics, the increase in sintering temperature entails higher fabrication costs. In contrast, a lower sintering temperature can reduce costs, but the performance of the actuator may be compromised. To address these issues, the Li-Sc co-doped 0.46PNN-0.23PIN-0.31 PT ceramics were produced in the present work. At a relatively low sintering temperature (950 °C), the synergy of multiple ferroelectric phases and defect polarization could be achieved, thereby augmenting the electromechanical properties of the material. At an optimal doping ratio of 0.6 mol% for both Li and Sc, the ceramics demonstrated superior performance metrics, including d₃₃ = 1000 pC/N, d₃₃∗ = 1050 p.m./V, k_p = 0.53, and ε_r = 8001. Applying the Rietveld refinement and Rayleigh analysis, it was established that the incorporation of Li is essential in the formation of a rhombohedral phase-dominated morphotropic phase boundary (MPB), which decreases polarization anisotropy amidst the coexisting phases, facilitating polarization rotation and significantly enhancing the piezoelectric properties of ceramics. The nanodomains within the material were detected through SS-PFM and PFM testing. Notably, Sc³⁺-induced defects disrupted the extended ferroelectric domains, fostering the emergence of nanodomains with higher activity, which in turn enabled to markedly improve the electromechanical performance of the ceramics even at the lower sintering temperature. This investigation not only provides a viable strategy for curtailing the manufacturing costs of multilayer actuators but also opens up new prospects for the low-temperature fabrication of piezoelectric materials and their applications.