题目：The impact of local structural heterogeneity on electrical properties of perovskite ferroelectrics
报告人： Prof. Shujun Zhang（ISEM/AIIM of University of Wollongong）
Perovskite ferroelectric materials are at the heart of numerous electronic devices, such as imaging transducer, piezoelectric sensors, energy harvesting and electrical energy storage capacitors, to name a few.
Relaxor-PT ferroelectrics show superior dielectric/piezoelectric properties, outperforming conventional ferroelectric PZTs, which greatly benefit medical ultrasound imaging. The good properties of relaxor-PT based materials are inherently associated with their unique local structural heterogeneity: the existence of nanoscale heterogeneous regions that coexists with normal ferroelectric domains. The contribution of these local structures has been theoretically modelled to be the origin of the ultrahigh dielectric and piezoelectric activities of relaxor based perovskite ferroelectric crystals, accounting for 50-80% of their respective room temperature values [1-4]. Based on the paradigm, recent developments have experimentally confirmed that modest changes in the polarizability of local structure, can be regarded as “seeds” to further enhance the dielectric properties of ABO3 perovskite solid solutions. The modified polycrystalline ceramics exhibit ultrahigh dielectric and piezoelectric properties, compared to their non-modified counterparts. In addition, the energy storage performance of the local structure tuned perovskite ferroelectrics is greatly enhanced, with energy density of >9J/cc (20 microns ceramic layer) and energy efficiency of >90% . The relationship between local structure and macroscopic properties has been established, try to understand the impact of local structure on dielectric properties, to explore high performance ferroelectric materials for energy harvesting and energy storage applications.
Shujun Zhang is Professor at ISEM/AIIM of University of Wollongong, prior to which, he was senior Scientist at Materials Research Institute and Professor at Materials Science and Engineering Department of the Pennsylvania State University. He is associate editor for Science Bulletin; IEEE Transaction on Ultrasounds, Ferroelectric and Frequency Control; Journal of the American Ceramic Society and Journal of Electronic Materials, section Editor-in-Chief for Crystals. He was recipient of Ferroelectrics Young Investigator Award of IEEE UFFC Society in 2011. He is senior member of IEEE and elected AdCom member of IEEE UFFC 2016-2018. He holds 7 patents and has authored/coauthored 400 papers, with SCI citation >10,000. He is now focusing on fabrication- microstructure- property- performance relationship of functional materials for piezoelectric sensor, transducer and energy storage/harvesting applications.