Synthesis and characterization of the novel Nb 3O 5F 5 niobium oxyfluoride: the term n=3 of the Nb nO 2 n−1 F n+2 series

Abstract

The solid-state synthesis of the oxyfluoride Nb 3O 5F 5, its crystal structure determined from X-ray powder diffraction data as well as some physical characterizations, are reported. Nb 3O 5F 5 constitutes the term n=3 of the Nb n O 2 n−1 F n+2 series related to the Dion–Jacobson phases. It crystallizes, at room temperature, in the tetragonal system (space group I4 /mmm (no. 139); Z=4; a=3.9135(1) Å, c=24.2111(2) Å, and V=370.80(3) Å 3). The crystal structure appears to be an in-between of the three-dimensional network of NbO 2F and the two-dimensional packing of NbOF 3 (term n=1 of the Nb n O 2 n−1 F n+2 series). This layered structure consists of slabs made of three Nb(O,F) 6 corner-linked octahedra in thickness ( n=3) shifted one from another by a ( 1 2 a+ 1 2 b )/translation. Oxygen and fluorine atoms are randomly distributed over all the ligand sites.