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Synthèse et étude de la structure et des propriétés physiques de composés MCuO2+d de type Delafossite excédentaires en oxygène.

Abstract : Because of the presence of eventually hole-doped triangular arrays of spin 1/2 Cu2+ cations, compounds such as YCuO2.5 or LaCuO2.66 could provide a better insight into the behaviour or topologically frustrated magnetic systems or high Tc superconducting cuprates. However, up to now the structure of these oxidised delafossites could not be reliably determined, because of the presence of a strong stacking disorder, which also hindered the interpretation of the physical properties. By careful optimisation of the chemical synthesis process, we were able to produce high quality samples of YCuO2.5 and LaCuO2.66. Their structures have been studied by combining electron diffraction and microscopy, x-ray synchrotron and neutron powder diffraction, and will be presented in details at the conference. For YCuO2.5, the structure was determined in an orthorhombic superstructure unit cell ao = aH√3; bo = cH; co = 2aH and space group Pnma. The Cu2+ cations form saw-tooth-like chains of corner-sharing triangles centred by oxygen anions. In LaCuO2.66, the delafossite-type cationic arrangement is modified by oxygen insertion, with in-plane shifts of copper cations. These cations adopt a square planar co-ordination, and the copper and oxygen ions are arranged as an almost regular Kagome lattice. The existence of a hole-doped Kagome lattice of spin 1/2 cations is a quite remarkable feature which deserves detailed experimental as well as theoretical investigation.
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https://tel.archives-ouvertes.fr/tel-00003032
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Submitted on : Thursday, June 19, 2003 - 4:58:02 PM
Last modification on : Wednesday, October 17, 2018 - 8:26:02 AM
Long-term archiving on: : Tuesday, September 7, 2010 - 4:33:00 PM

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  • HAL Id : tel-00003032, version 1

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UJF | CNRS

Citation

Ovidiu Garlea. Synthèse et étude de la structure et des propriétés physiques de composés MCuO2+d de type Delafossite excédentaires en oxygène.. Matière Condensée [cond-mat]. Université Joseph-Fourier - Grenoble I, 2001. Français. ⟨tel-00003032⟩

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