title: α-Na3M2(PO4)3 (M = Ti, Fe): absolute cationic ordering in NASICON-type phases.
abstract: The structure of the fully ordered α-Na(3)Ti(2)(PO(4))(3) NASICON compound was elucidated using high-quality single-crystal data. The cation/vacancy distribution forms a homogeneous 3D arrangement and could represent the absolute cationic ordering available in the full Na(3)M(2)(PO(4))(3) series, as verified for M = Fe. For M = Ti, the reversible α → γ transition was observed at 85 °C, leading to the standard disordered R ̅3c γ model. Through JPDF analysis, the most probable Na(+) zigzag M(2)-M(1) diffusion scheme was directly deduced using our accurate crystallographic data.
authors: Unité de Catalyse et de Chimie du Solide, UCCS, CNRS UMR8181, Université Lille Nord de France, 59655 Villeneuve d'Ascq, France.
authors: Houria
authors: H
authors: Kabbour
authors: Daniel
authors: D
authors: Coillot
authors: Marie
authors: M
authors: Colmont
authors: Christian
authors: C
authors: Masquelier
authors: Olivier
authors: O
authors: Mentré