Conditions Extrêmes et Matériaux : Haute Température et Irradiation

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M.Allix, M.H.Chambrier, E.Véron, F.Porcher, M.R.Suchomel, F.Goutenoire, 'Synthesis and structure determination of the high temperature form of La2WO6', Cryst. Growth Des. 11 5105 (2011) doi:10.1021/cg201010y

This article presents the synthesis, structure determination, and structure analysis of α-La2WO6. This high temperature polymorph was directly observed using laboratory in situ high temperature X-ray powder diffraction and isolated at room temperature by rapid quenching from 1600°C. Ab initio structure determination has been performed at room temperature by combining electron diffraction results with an analysis of synchrotron and neutron powder diffraction data by charge-flipping algorithm methods. The α-La2WO6 phase is found to crystallize in the Pm21n (n°31) orthorhombic space group (Z=6) with cell parameters: a=16.5513(1)Å, b=5.52003(3)Å, c=8.88326(3)Å and a measured density of 6.82(1) at room temperature. This previously uncharacterized high temperature α-La2WO6 form (>1450°C) may be described as a regular paving between six [WO6] octahedra alternating with twelve isolated lanthanum atoms. The conductivity properties have been measured and compared to the low temperature (β) polymorph.