%0 Journal Article
%T Soft-mode dynamics in micrograin and nanograin ceramics of strontium titanate observed by hyper-Raman scattering
%+ Laboratoire Charles Coulomb (L2C)
%+ Laboratoire Structures, Propriétés et Modélisation des solides (SPMS)
%A Hehlen, Bernard
%A Al-Zein, A.
%A Bogicevic, Christine
%A Gemeiner, P.
%A Kiat, Jean-Michel
%< avec comité de lecture
%Z L2C:12-261
%@ 1098-0121
%J Physical Review B: Condensed Matter and Materials Physics (1998-2015)
%I American Physical Society
%V 87
%P 014303
%8 2013-01-22
%D 2013
%R 10.1103/PhysRevB.87.014303
%K SrTiO3
%K Soft mode
%K ceramic
%K hyper-RAman
%Z Physics [physics]/Condensed Matter [cond-mat]/Disordered Systems and Neural Networks [cond-mat.dis-nn]Journal articles
%X The low-frequency vibrations of micro- and nanograin ceramics of strontium titanate are investigated by hyper-Raman spectroscopy. The combination of a confocal optical microscope with an ultranarrow Notch filter enabled an accurate spectroscopy on both the Stokes and anti-Stokes side down to about 8 cm−1. A splitting of the soft mode into E-u- and A-2u-symmetry vibrations is clearly observed in the micrograin sample. The peculiar temperature dependence of ω^2_A2u−ω^2_Eu emphasizes a nonlinear coupling between the square of the TiO6 tilting angle and the spontaneous strain c/a − 1. In addition, the very different temperature behavior of the linewidth of the two soft components is assigned to the growth of a disorder anisotropy on cooling, probably on the titanium site.
%G English
%L hal-00787294
%U https://hal.science/hal-00787294
%~ EC-PARIS
%~ CNRS
%~ SPMS
%~ ECP-DR
%~ L2C
%~ SPMS-ECP
%~ SPMS-AXE1
%~ SPMS-AXE2
%~ SPMS-AXE3
%~ INC-CNRS
%~ MIPS
%~ UNIV-MONTPELLIER
%~ GS-PHYSIQUE
%~ UM-2015-2021
%~ TEST2-HALCNRS