Multilayer-induced stress manipulation for superior piezoelectric performance and temperature stability in lead-free piezoceramics

The sensitivity and reliability of piezoelectric accelerometers heavily rely on the piezoelectric coefficient and temperature stability of their core components. However, the inherent nature of polycrystalline phase boundaries in lead-free piezoceramics poses a significant challenge in simultaneously achieving excellent comprehensive properties. This study proposes a co-fired multilayer piezoceramics architecture to achieve nearly 10-fold increase in piezoelectric coefficient (from 165 pC/N of bulks to 1568 pC/N of multilayer piezoceramics) and significantly enhanced temperature stability in potassium sodium niobate based ceramics, breaking the long-standing trade-off relationship between the two core parameters. The superior temperature stability is achieved by introducing residual thermal stresses in the inner electrode and ceramic layers within the multilayer structure. The introduced internal stress both stabilizes the lower symmetry phases and restrained domain switching. The prototype acceleration sensors were developed and the multilayer piezoceramics device shows a good linearity and higher sensitivity compared to bulk ceramics, with only a slight property fluctuation with temperature increases. This work establishes a feasible strategy for synergistically optimizing piezoelectricity and temperature stability in lead-free ceramics, extending their sensor application for structural health monitoring.