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0346819_Tan

CAREER: The Evolution of Polar Nanoregions and Its Coupling with Cation-Ordered Domains in Pb(B'B'')O 3 Relaxor Ferroelectrics Xiaoli Tan, Iowa State University, DMR 0346819.

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0346819_Tan

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  1. CAREER: The Evolution of Polar Nanoregions and Its Coupling with Cation-Ordered Domains in Pb(B'B'')O3 Relaxor FerroelectricsXiaoli Tan, Iowa State University, DMR 0346819 Two significant research findings are made on this project in the past year. The first one is the enhancement of the cation order in Pb(Mg1/3Nb2/3)O3 through oxygen vacancy. Pb(Mg1/3Nb2/3)O3 is one of the most important compounds used in transducers, actuators, and electrical capacitors. Its electrical properties are dictated by its degree of cation order. For the first time, my group demonstrated the enhancement of cation order with combined O-vacancy and Zr-doping. The second major finding is the discovery of the auxetic behavior in ferroelectric ceramics. Auxetics refers to materials that become thicker in transverse directions when longitudinally stretched. Auxetic materials are rare and most of them are organic polymers with hinge-like structures. For the first time, my group discovered an auxetic behavior in monolithic ferroelectric polycrystalline ceramics, a technologically important family of materials, under electrical loads. Fig. 1 The oxygen-vacancy mechanism. Ref.: X. Zhao, W. Qu, and X. Tan, Journal of the American Ceramic Society91, 3031-3038 (2008). Fig. 2 Transverse expansion under electrical loads. Ref.: X. Tan, W. Jo, T. Granzow, J. Frederick, E. Aulbach, and J. Rödel, Applied Physics Letters94, 042909/1-3 (2009).

  2. CAREER: The Evolution of Polar Nanoregions and Its Coupling with Cation-Ordered Domains in Pb(B'B'')O3 Relaxor FerroelectricsXiaoli Tan, Iowa State University, DMR 0346819 • The primary educational activity for this CAREER grant is to educate and train undergraduate students, with emphasis on underrepresented groups, in the PI’s research lab. Through the support of this project, the following undergraduate students were recruited and trained with electroceramics processing and characterization. • Summer 2008, Laura Choate from Univ. of Arizona • Fall 2008 & Spring 2009, Emily Decker from ISU • Summer 2009, Daniel Marincel from Missouri Univ. of Sci. and Technol. • The PI has also been actively involved in K-12 education at local schools. In the summer of 2009, the PI made financial contributions through this project to support the Ames Middle School Science Olympiad team to attend the 2009 Science Olympiad National Tournament in Augusta, Georgia. In addition, on June 12th, 2009, the PI invited and hosted Mary Glenn, Dan Andrews, and Peg Barbour, the Ames Middle School science teachers, for a visit to the PI’s research lab and the Materials Science and Engineering Department at ISU. The activities for the Ames Middle School science teachers on June 12, 2009. Upper: the butterfly wing under SEM. Lower, the piezoelectric effect demonstrator.

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