Analysis of the local structure of phosphorus-substituted LAMOX oxide ion conductors

Bholanath Pahari (1) , Noureddine Mhadhbi (1) , Gwenaël Corbel (1) , P. Lacorre (1) , Jens Dittmer (1)

1 IMMM - Institut des Molécules et Matériaux du Mans

The effect of partial substitution of molybdenum by phosphorus on the global and local structural arrangement of the fast oxide-ion conductor La2Mo2O9 (LAMOX) has been studied by X-ray powder diffraction as well as 139La and 31P solid state NMR. The diffraction patterns show that La2Mo2−yPyO9−y/2 forms a solid solution at low phosphorus concentrations, and that there is a structural phase transition upon increasing phosphorus concentration. This phase transition is also reflected in 139La and 31P NMR spectra. The possibility to excite 31P multiple-quantum coherences of one of the 31P NMR signals gives evidence of an accumulation of phosphorus atoms on neighbouring Mo-type sites already before formation of three-dimensional precipitates. On the basis of our X-ray and NMR results we propose a possible structural arrangement of the compound La2Mo2−yPyO9−y/2 that explains the experimental observations by crystal twinning.

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Chimie inorganique; Matériaux; Cristallographie

Bholanath Pahari, Noureddine Mhadhbi, Gwenaël Corbel, P. Lacorre, Jens Dittmer. Analysis of the local structure of phosphorus-substituted LAMOX oxide ion conductors. Dalton Transactions, 2012, 41 (18), pp.5696. ⟨10.1039/c2dt12389d⟩. ⟨hal-02189727⟩