Remarkably enhanced piezoelectric temperature stability in lead-free ferroelectrics by modulating element diffusion at laminated interfaces

Advanced ferroelectrics with a combination of large piezoelectric response and good temperature stability are crucial for high sensitivity and reliability in sensing and actuating devices. However, these two key factors usually do not cooperate with each other especially for lead-free piezoelectric materials, while achieving high piezoelectricity is normally accompanied by poor stability or vice versa. Herein, we report an approach to resolve the incompatibility between piezoelectric coefficient and temperature stability by designing laminated compositions and controlling element diffusion at multi-interfaces, leading to giant piezoelectricity (d₃₃∼450 pC/N) with a minimal variation of about 7 % over a wide temperature range (25°C–90 °C), exceeding the classical lead-free systems. By elaborately modulating the diffusion conditions, the concentration of the element shows a gradually change across the laminated structure, contrast to the terraced distribution of element concentration in traditional laminated structure. Further structure characterization clarifies that the gradually change element concentration contributes to a smooth evolution of crystal structure, which is beneficial for the transition of domain switching between different composition layers, resulting in the improvement of piezoelectric temperature stability. The piezoelectric accelerometer manufactured by modulated ceramics was tested by a vibration system and turned out to be temperature stable compared with commercial PZT-4 sensor. This finding provides an effective and straightforward approach for developing superior ferroelectrics with enhanced temperature stability and high piezoelectric coefficient, promising the potential applications of piezoelectric devices concurrently approaching exceptional sensitivity and thermal reliability.