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CATEGORIES:Department of Materials Science &amp\; Metallurgy 
 Seminar Series
SUMMARY:Dislocation-Based Functionality in Oxides - Prof. 
 Dr. Jürgen Rödel\, Department of Materials and Ear
 th Sciences\, TU Darmstadt
DTSTART;TZID=Europe/London:20191122T150000
DTEND;TZID=Europe/London:20191122T160000
UID:TALK126484AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/126484
DESCRIPTION:While my group in the last 14 years worked mostly 
 on lead-free piezoceramics\, this topic has mature
 d considerably and we now mostly work with industr
 y to transfer knowledge into application. Our new 
 topic with currently four researchers and four ope
 nings centers on dislocation-based functionality: 
 \nDislocations in oxides are typically heavily cha
 rged and embedded in a shell of compensating space
  charges. Therefore they provide a linear or two-d
 imensional array of charges stable up to high temp
 erature without any chemical dopant. In the litera
 ture dislocations have been demonstrated to enhanc
 e oxygen conductivity and to improve the figure of
  merit of thermoelectrics by reducing thermal cond
 uctivity through phonon scattering by dislocations
 . Dislocations have been suggested to improve inte
 rfacial reaction kinetics and have been theoretica
 lly predicted to pin domain walls in ferroelectric
 s. \nIn Darmstadt we have so far focused on establ
 ishing a set of techniques to introduce a high den
 sity of bulk dislocations into single crystals at 
 room temperature or enhanced temperature and to st
 udy (dislocation) creep in polycrystalline oxides.
  Structural investigations have been performed by 
 dark-field X-ray diffraction\, rocking curve analy
 sis\, TEM\, PFM\, NMR and etching techniques. The 
 first property evaluations have been done with res
 pect to electrical and thermal conductivity and do
 main wall pinning. \nSelect examples will be provi
 ded on dislocation structures\, electrical and the
 rmal conductivity. We have been working on SrTiO3\
 , BaTiO3\, KNbO3\, TiO2 and ZrO2.
LOCATION:Goldsmiths 1\, Lecture Theatre\, Department of Mat
 erials Science &amp\; Metallurgy
CONTACT:Yonatan Calahorra
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