清華大學材料科學與工程研究院《材料科學論壇》學術報告

報告時間：2023年11月17日上午10:00

報告人：Prof. Andrew J Bell（University of Leeds, UK）

報告地點：清華大學逸夫技術科學樓A205學術報告廳

邀請人：李敬鋒老師

Inside Piezoelectricity: the structural origins of electromechanical coupling

報告簡介：

In the quest for new piezoelectric materials, understanding how crystal chemistry impacts the intrinsic piezoelectric effect remains elusive. This study establishes a defining link between the piezoelectric coupling coefficient and differentials in observable structural variables, specifically strain and polarization, in both direct and converse effects. Notably, maximizing the piezoelectric coupling factor and charge coefficient requires significant displacements of cations, while, unexpectedly, minimal displacements of anions are optimal. Density Functional Theory (DFT) calculations on perovskites validate this, revealing enhanced charge and coupling coefficients when restricting oxygen ion displacements. The widely observed relationship between d₃₃ and k₃₃ in perovskite oxides is attributed to the invariant piezoelectric contribution of the oxygen sublattice. The study delves into anomalies in soft PZTs and relaxor-lead titanate single crystals, providing insights into their behaviors. These findings offer crucial crystal chemistry "design rules" for high-performance piezoelectric materials, particularly valuable in guiding the selection of functional groups for new organic piezoelectric materials with a larger design space than perovskite oxides.

報告人簡介：

Andrew Bell has been Professor of Electronic Materials at the University of Leeds, School of Chemical and Process Engineering since 2000. He was elected a Fellow of the Royal Academy of Engineering in 2016 and was elevated to Fellow of IEEE in 2019. He was awarded the Verulam Medal of the Institute of Materials in 2014. He has received the IEEE’s Ferroelectrics Recognition Award (2012) and Robert E Newnham Ferroelectrics Award (2022). His work on understanding the property enhancement mechanisms in Sm-doped piezoelectric ceramics won the American Ceramic Society’s Edward C Henry award for 2021. He is currently the 2023 IEEE-UFFC Distinguished Lecturer in Ferroelectrics. He has undertaken research on a wide range of topics in ferroelectric and dielectric materials, encompassing basic science, materials processing, structural & electrical characterization and device physics, including pyroelectric materials and devices, microwave dielectrics and piezoelectrics.