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SUMMARY:The effect of high-pressure on ABO3 perovskite-type oxides: Ferroe
 lastics\, ferroelectrics &amp\; multiferroics - Jens Kreisel (CNRS\, Greno
 ble)
DTSTART:20111125T140000Z
DTEND:20111125T150000Z
UID:TALK34727@talks.cam.ac.uk
CONTACT:Ian Farnan
DESCRIPTION:The understanding of ABO3 perovskite remains one of the most c
 hallenging topics at the interface between solid state chemistry and solid
  state physics. The use of pressure for the investigation of perovskites h
 as remained relatively rare\, also due to the experimental difficulties\, 
 which have now been overcome for a number of years. As a consequence\, we 
 observe an evolution of high-pressure studies from a “niche” activity\
 , reserved to some experts\, to an increasingly important activity.\nIn my
  presentation I will first recall the perovskite structure and the relatio
 n between the different structural distortions and physical properties. I 
 will then discuss the pioneer rules of Samara [1] which have guided for ye
 ars the interpretation of the effect of high-pressure on perovskites. In t
 he second part of the talk I will focus on our own observations by high-pr
 essure Raman scattering and synchrotron scattering experiments of three cl
 asses of perovskites : (i) Ferroelastics\, such as LaAlO3\, SrTiO3 & CaTiO
 3 [2-5]\, (ii) Classic ferroelectrics like PbTiO3 [6-7] and\, in some more
  detail\, (iii) The multiferroic BiFeO3 [8-9].\nThese different examples w
 ill allow discussing in more general terms the effect of high-pressure on 
 octahedra tilting\, cation displacement and the competition between these 
 two instabilities\n\n[1]	G. A. Samara\, T. Sakudo\, K. Yoshimitsu\, Phys. 
 Rev. Lett. 35\, 1767 (1975).\n[2]	P. Bouvier\, J. Kreisel\, J. Phys.: Cond
 . Matt. 14\, 3981 (2002).\n[3]	M. Guennou\, P. Bouvier\, G. Garbarino\, J.
  Kreisel\, J. Phys.: Cond. Matt. 23\, 395401 (2011).\n[4]	M. Guennou\, P. 
 Bouvier\, J. Kreisel\, D. Machon\, Phys. Rev. B 81\, 054115 (2010).\n[5]	M
 . Guennou\, P. Bouvier\, B. Krikler\, J. Kreisel\, R. Haumont\, Phys. Rev.
  B 82\, 134101 (2010).\n[6]	P.-E. Janolin\, P. Bouvier\, J. Kreisel et al.
  Phys. Rev. Lett. 101\, 237601 (2008).\n[7]	I. A. Kornev\, L. Bellaiche\, 
 P. Bouvier\, B. Dkhil\, J. Kreisel\, Phys. Rev. Lett. 95\, 196804 (2005).\
 n[8]	R. Haumont\, P. Bouvier\, J. Kreisel et al. Phys. Rev. B 79\, 184110 
 (2009).\n[9]	M. Guennou\, P. Bouvier\, G. S. Chen\, R. Haumont\, J. Kreise
 l\, Phys. Rev. B\, accepted (2011).\n\n
LOCATION:Harker 2 lecture room\, Department of Earth Sciences\, Downing Si
 te
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