报告题目：High Piezoelectricity in relaxor-PT based Materials with Local Structural Heterogeneity
报告人：Prof. Shujun Zhang (ISEM, Australian Institute for Innovative Materials, University of Wollongong)
Among all known ferroelectric materials, the perovskite ferroelectric materials exhibit the highest piezoelectric coefficient, and thus are at the heart of numerous electronic devices, such as imaging transducer, piezoelectric sensors and energy harvesting, to name a few. PZT based ceramics with perovskite structure have been the mainstay piezoelectric materials and occupy the largest share of the piezoelectric ceramics market for numerous applications, due to their large piezoelectric coefficients and electromechanical coupling factors near the morphotropic phase boundary (MPB) and the ability to tailor properties between soft and hard piezoelectric responses.
Relaxor-PT ferroelectrics show high dielectric and piezoelectric properties, far outperforming conventional PZTs, greatly benefit medical ultrasound imaging. The good properties of relaxor-PT based materials are inherently associated with the unique local structural heterogeneity: the existence of nanoscale heterogeneous regions that coexists with normal ferroelectric matrix. Based on this paradigm, recent developments have experimentally confirmed that modest changes in the polarizability of local structure, which is induced by the A site donor dopants, can be regarded as “seeds” to further enhance the dielectric properties of ABO3 perovskite solid solutions. The local structural heterogeneity, together with the morphotropic phase boundary composition, synergistically contribute to the dielectric properties. The modified polycrystalline ceramics exhibit ultrahigh dielectric and piezoelectric properties, compared to their non-modified counterparts, being on the order of 13,000 and 1500pC/N, respectively, while the piezoelectric coefficient reaches ~4000pC/N in single crystal form, far superior to the state-of-the-art ferroelectric single crystals. 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 various electromechanical applications.
Shujun Zhang is Professor at ISEM, Australian Institute for Innovative Materials, University of Wollongong, Australia, prior to which, he was Professor at Materials Science and Engineering Department and Senior Scientist at Materials Research Institute of The Pennsylvania State University, US. He is associate Editor-in-Chief of IEEE Transaction Ultrasound, Ferroelectric and Frequency Control; associate editor of Science Bulletin; Journal of the American Ceramic Society and Journal Electronic Materials, section EIC of Crystals. He is fellow of American Ceramic Society (2019) and senior member of IEEE (2010), elected AdCom member of IEEE-UFFC. He holds 8 patents and has coauthored 500 papers, with Google Scholar citation >17,000 and H index of 63. He is now focusing on fabrication-microstructure-property-performance relationship of functional materials for piezoelectric sensor, transducer and energy storage/harvesting applications.