Abstract：
Piezoelectric materials that can function at harsh environment without failure are desired for structural health monitoring and/or nondestructive evaluation of the modern aerospace structures at both high temperature up to 1200oC and cryogenic temperature around -150oC, in addition, they will also benefit the safety of electrical /nuclear power plants and energy storage facilities.
The operational temperature range of the smart transducers is limited by the sensing capability of the piezoelectric material at challenging temperatures, increased conductivity and mechanical attenuation, variation of the piezoelectric properties with temperature. This paper discusses properties relevant to sensing applications, including ferroelectric materials and non-ferroelectric pizoelectric crystals.
Recent developments in advanced piezoelectrics are highlighted, showing piezoelectric activity versus proposed usage temperature range for various piezoelectric materials. The relaxor-PT ferroelectric crystals with perovskite structure were found to possess the highest piezoelectric properties, with d33 values being on the order of >2000pC/N, however, their usage temperature range is limited by the low ferroelectric phase transition TRTs [1], of particular interest is that relaxor-PT crystals were reported to show yet high piezoelectric activity at cryogenic temperature of -150oC. On the other hand, ferroelectric materials with the tungsten bronze and Aurivillius structures possess medium piezoelectric properties, ranging from 10pC/N to 100pC/N, with usage temperatures up to 550oC, limited by TC or low electrical resistivity at elevated temperatures. It should be noted that though LN crystals possess a TC of 1150oC, their low resistivities and oxygen loss at elevated temperature restrict applications to < 600oC. Generally, nonferroelectric piezoelectric single crystals possess low sensitivity, falling in the range of 1-20pC/N, however, their ultralow mechanical and dielectric losses, and high electrical resistivities, make them ideal candidates for ultra-high temperature sensing applications [2].

Bio
Shujun Zhang received Ph.D. from Shandong University, China, in 2000. 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 was a recipient of the Ferroelectrics Young Investigator Award of IEEE UFFC Society in 2011. He is senior member of IEEE and member of American Ceramic Society. He holds five patents and has authored/coauthored more than 300 papers in refereed journals with H index of 45 and total citation of >8600 (http://scholar.google.com/citations?user=TnytfhkAAAAJ&hl=en&oi=ao). He is now focusing on the structure- property- performance relationship of high temperature and high performance piezoelectric crystals and ceramics, for sensor and transducer applications.