Local structure of magnetite and zirconates of perovskite type by resonant diffraction and X-ray absorption

Abstract : This thesis concerns the study of two classes of the oxides by the resonant x-ray diffraction and X-ray absorption spectroscopy for the magnetite and perovskites. The electronic structure of Fe3O4 has been studied using Fe K-edge spectroscopy in order to confirm/refute the model of the charge order in the low temperature phase. The developed method was permitted to obtain quantitative information using the large number of reflections and to confirm the presence of the charge order (Fe2.5±δ δmax=0.12, δmin=0.04). The perovskites were studied to clearly understand the geometrical nature of their phase transition. The analysis of K-edge XANES spectra of the Zr for PbZrO3 rejected the "displacement" model at low temperature but the conservations of the local distortions in the cubic phase were indicated. The interpretation of the ferroelectric structural transition was proposed in terms of changes of the local environment of Zirconium in the framework of the "spherical" model.
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Contributor : Elena Nazarenko <>
Submitted on : Thursday, March 15, 2007 - 1:00:16 PM
Last modification on : Thursday, February 14, 2019 - 1:21:00 AM
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Elena Nazarenko. Local structure of magnetite and zirconates of perovskite type by resonant diffraction and X-ray absorption. Mathematical Physics [math-ph]. Université Joseph-Fourier - Grenoble I, 2007. Russian. ⟨tel-00136821⟩

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