Enhancing piezoelectric coefficient and thermal stability in lead-free piezoceramics: insights at the atomic-scale
Jinzhu Zou, Miao Song, Xuefan Zhou, Wenchao Chi, Tongxin Wei, Kechao Zhou, Dou Zhang, Shujun Zhang
Abstract
Given the highly temperature-sensitive nature of the polymorphic phase boundaries, attaining excellent piezoelectric coefficient with superior temperature stability in lead-free piezoceramics via direct compositional design remains a formidable challenge. We demonstrate the synergistic improvement of piezoelectric coefficient and thermal stability in lead-free piezoceramics via atomic-scale local ferroelectric structure design. Via modulation of the local Landau energy barrier at doping sites, we effectively mitigate fluctuations in piezoelectric d33. Our approach achieves an impressive d33 of ~430 pC/N with a minimal temperature fluctuation range (△d33 ~ 7%) across the room temperature to 100 °C in potassium sodium niobate ceramics. Further optimization through annealing extends this temperature up to 150 °C (△d33 ~ 8%) while maintaining a high d33 of ~380 pC/N, rivaling the performance of classic temperature stable lead zirconate titanate. This work establishes a framework for addressing the dilemma between high piezoelectric coefficient and inadequate temperature stability in lead-free piezoceramics. The authors reveal that the incorporation of doping elements with varying electronic structures and ionic radii alters the atomic-scale configuration, thereby affecting the local energy barrier associated with polarization rotation.