Synthesis and characterization of the novel Nb3O5F5 niobium oxyfluoride:: the term n=3 of the NbnO2n-1Fn+2 series

The solid-state synthesis of the oxyfluoride Nb3O5F5, its crystal structure determined from X-ray powder diffraction data as well as some physical characterizations, are reported. Nb3O5F5 constitutes the term n = 3 of the NbnO2n-1Fn+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) Angstrom, c = 24.2111(2) Angstrom, and V = 370.80(Angstrom(3)) The crystal structure appears to be an in-between of the three-dimensional network of NbO2F and the two-dimensional packing of NbOF3 (term n = 1 of the NbnO2n-1Fn+2 series). This layered structure consists of slabs made of three Nb(O2F)(6) corner-linked octahedra in thickness (n = 3) shifted one from another by a (1/2a + 1/2b)/transiation. Oxygen and fluorine atoms are randomly distributed over all the ligand sites. (C) 2004 Elsevier Inc. All rights reserved.