To cite this version:A. Slodczyk, Ph. Colomban, M. Pham-Thi. Role of the TiO octahedra on the ferroelectric and piezoelectric behaviour of the poled PbMgNbO-xPbTiO (PMN-PT) single crystal and textured ceramic. Journal of Physics and Chemistry of Solids, Elsevier, 2009, 69 (10) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A c c e p t e d m a n u s c r i p t temperature indicates precisely the continuous evolution of the local symmetry towards the cubic one. The temperature evolution of the Rayleigh wing parameters appears sensitive to the phase transitions presence.

The Raman and infrared spectra of the superionic protonic conductor CsHS04(CsDS04) were investigated in the 18450 K range. Polarized single crystal Raman and infrared reflection spectra were also studied at room temperature. An assignment of bands due to internal and external vibrations is given in terms of symmetry species and approximate type of motion. The spectroscopic results, in particular the behaviour of the Raman bands as a function of temperature, are used to discuss the crystalline structures of various phases, hydrogen bonding, the type and degree of structural disorder, phase transitions and conductivity.

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The effect of uniaxial pressing and grinding on pure and europium-doped CaS powders prepared by the alkaline polysulfide flux method is studied by electron spin resonance (ESR). F+ centers are generated in the bulk of CaS particles and their ESR spectra can be easily separated from those of other paramagnetic species by using a 90" out-of-phase detection. This is possible because of the very long transverse relaxation time Ts of F+ centers. It is thought that the primary defects induced by mechanical stress are bulk F centers, which are next partially converted into Ff centers by reduction of metal ion impurities (Eu3' ,Crs',Cu2') and native hole centers. Heat treatments in air of mechanically stressed powders show that F+ centers firstly diffuse to the particle surface forming low-symmetry F,f centers for temperatures ranging from 300 to 700 K. Atmospheric oxygen then transforms F: centers into ESR silent O-ions except if they are stabilized by Naf impurities originating from the flux, For temperatures higher than 700 K, these centers are then converted into paramagnetic SO, centers. The reason for the strong decrease of Eu2+ emission intensity (X=645 nm) following mechanical stress is discussed. The study of the fine structure of Mn2' natural impurity shows that local order is strongly disturbed in CaS particles by mechanical stress. 0 1995 American Institute of Physics.