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Seminar – The impact of local structure on macroscopic properties of ABO3 perovskite relaxor – Dr. Shujun Zhang
May 19, 2017 @ 11:30 am
|The impact of local structure on macroscopic properties of ABO3 perovskite relaxor
Shujun Zhang1*, Fei Li2, Long-Qing Chen2 and Thomas R. Shrout2
1 Institute for Superconducting and Electronic Materials, Australia Institute of Innovative Materials, University of Wollongong, NSW 2500, Australia
2 Materials Research Institute, Pennsylvania State University, University Park, PA 16802, US
Relaxor materials with ABO3 perovskite structure have been actively studied for the potential optical, dielectric and piezoelectric applications. Relaxors show remarkable properties, such as high dielectric constant, low hysteresis and frequency dependent dielectric properties, being associated with their unique local structure: the existence of polar nano regions (PNRs), a nanoscale inhomogeneity that coexists with normal ferroelectric domains .
The contribution of these local structures has been theoretically modeled to be the origin of the ultrahigh dielectric and piezoelectric activities of relaxor based perovskite ferroelectrics, accounting for 50-80% of their respective room temperature values . Based on the paradigm, recent developments have experimentally confirmed that modest changes in the polarizability of PNRs and/or local structure, can be regarded as “seeds” to further enhance the dielectric and piezoelectric properties of ABO3 perovskite relaxor based solid solutions. The modified polycrystalline ceramics have been shown to exhibit ultrahigh dielectric and piezoelectric properties, compared to their non-modified counterparts, being on the order of >10,000 and >1000pC/N, respectively. The relationship between local structure and macroscopic properties has been established, try to understand the impact of local structure on dielectric and piezoelectric properties, to explore high performance ferroelectric materials for sensor and ultrasound transducer applications.
References: L. E. Cross, “Relaxor ferroelectrics,” Ferroelectrics 76, 241 (1987).  F. Li et al, “The origin of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution crystals,” Nature Communications, 7, 13807 (2016).
Shujun Zhang received Ph.D. from Shandong University, China, in 2000. He is Future Fellowship Professor at ISEM/AIIM of University of Wollongong, prior to which, he is senior Scientist at Materials Research Institute and Professor at Materials Science and Engineering Department of The Pennsylvania State University. He is associate editor for IEEE Transaction UFFC, Journal of the American Ceramic Society and Journal of Electronic Materials, he is the section Editor-in-Chief for “Crystal Engineering” section of the MDPI journal, Crystals. He was a recipient of the Ferroelectrics Young Investigator Award of IEEE UFFC Society in 2011. He is senior member of IEEE and elected AdCom member of the IEEE UFFC society during 2016-2018. He holds five US patents and has authored/coauthored more than 380 papers in refereed journals (http://scholar.google.com/citations?user=TnytfhkAAAAJ&hl=en&oi=ao), with google scholar citation of >11,000 and H index of 53. He is now focusing on the fabrication- microstructure- property- performance relationship of high performance piezoelectric crystals and ceramics, including lead free materials, for sensor, transducer and energy storage/harvesting applications.