An effective index for high-performance piezoelectrics

Piezoelectric materials have been attracting wide research interest for decades due to their ability to interconvert mechanical and electrical energy. Various mechanisms from different perspectives have been proposed to explain high piezoelectricity; however, a unified framework across diverse perovskite piezoelectric systems remains elusive. Yao et al. introduced a concept termed fluctuating local polarization (FLP) as an effective index for high piezoelectricity in perovskite ferroelectrics. FLP describes the composition-dependent piezoelectric performance in individual solid solutions and also accounts for high piezoelectricity across distinct systems. The FLP metric integrates the magnitude of local electric dipoles and the disorder of their orientations. This concept does not supersede traditional viewpoints but rather rationalizes them under a common microscopic index: local polarization flexibility. FLP is not merely an explanatory fingerprint of high piezoelectricity; it can also serve as a practical reference for engineering the next generation of ferroelectric materials.