BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Memento EPFL//
BEGIN:VEVENT
SUMMARY:Point Defects in Metal Oxides and Their Interactions with Electric
  Fields
DTSTART:20180305T131500
DTEND:20180305T141500
DTSTAMP:20260509T234514Z
UID:af581d2d0dbecb8661c0a4546c10eca4cde59211affc4a4a34727d64
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Elizabeth C. Dickey\, Department of Materials Science an
 d Engineering\, North Carolina State University USA\nLattice point defects
  and their coupling with electronic defects dominate the overall electrica
 l properties of electroceramic materials\, and thus great effort is expend
 ed on controlling the defect equilibria via oxygen activity during process
 ing and/or doping.  In device applications\, because the lattice defects 
 are typically charged\, the applied voltage provides a strong driving forc
 e for defect migration. When the electrodes are impermeable to mass transp
 ort\, the spatio-temporal redistribution of defects can cause time-depende
 nt increases in conductivity in many electroceramic devices. Our research 
 into this phenomenon combines electrical transport measurements with elect
 ron microscopy analyses to understand the mesoscopic redistribution of poi
 nt defects as a function of temperature\, electric field and time. In syst
 ems for which electronic transport is limited by injection at the electrod
 e\, we find that the accumulation of the charged defects can modulate the 
 electrode Schottky barrier\, allowing for greater carrier injection. At hi
 gh electrical potentials\, the non-stoichiometry in the near-electrode reg
 ions can become very large\, inducing defect clustering and ordering. The 
 implications of this defect redistribution process and its reversibility a
 re discussed within the context the overall electrical transport character
 istics.\n \nJ.N. Baker\, P.C. Bowes\, D.M. Long\, A. Moballegh\, J.S. Har
 ris\, E.C. Dickey\, D.L. Irving\, “Defect Mechanisms of Coloration in Fe
 -doped SrTiO3 from First Principles\,” Applied Physics Letters\, 110 (12
 ) 122903 (2017). DOI: 10.1063/1.4978861.\nJ.-J. Wang\, H.-B. Huang\, T.JM 
 Bayer\, A. Moballegh\, Y. Cao\, A. Klein\, E.C. Dickey\, D.L. Irving\, C.A
 . Randall\, L.-Q. Chen\, “Defect chemistry and resistance degradation in
  Fe-doped SrTiO3 single crystal\,” Acta Materialia\, 108\, 229-240 (2016
 ). DOI: 10.1016/j.actamat.2016.02.022\nA. Moballegh and E.C. Dickey “Ele
 ctric-Field-Induced Point Defect Redistribution in Single-Crystal TiO2 and
  Effects on Electrical Transport\,” Acta Materialia\, 86 (2015) 352–36
 0  (2015). DOI: 10.1016/j.actamat.2014.11.032\n\nBio: Elizabeth Dickey a 
 Professor of Materials Science and Engineering and the Director of the Cen
 ter for Dielectrics and Piezoelectrics at North Carolina State University.
  Her research aims to develop processing-structure-property relationships 
 for materials in which the macroscopic physical properties are governed by
  point defects\, grain boundaries or internal interfaces. Particular empha
 sis is placed on understanding the role of these material defects on elect
 rical and chemical transport in dielectric materials.  Her research invol
 ves using an array of analytical techniques\, in particular electron micro
 scopy and spectroscopy\, to understand the structure and chemistry of mate
 rials at the nanometer length scale. She has over 150 peer-reviewed journa
 l publications in these areas\, which have over eleven-thousand citations.
  In 1999 she received the Presidential Early Career Award for Scientists a
 nd Engineers (PECASE) for her work on metal-ceramic interfaces.  In 2010 
 she became a fellow of the American Ceramic Society\, has served on the Bo
 ard of Directors and was awarded the Fulrath Award by the Society in 2012 
 in recognition of her technical contributions related to the characterizat
 ion of functional ceramics and composites. She has served as an editor for
  Microscopy and Microanalysis and is currently an editor for the Journal o
 f the American Ceramic Society.\n\n 
LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR