The vanadium oxide bronze Cu2.33−xV4O11. Solid state chemistry, XRD

Abstract

Abstract Solid state chemistry of the vanadium oxide bronze (VOB) Cu 2.33− x V 4 O 11 shows that at 600°C the synthesis in both Cu 2 O or CuOV 2 O 5 V 2 O 4 systems leads to the conclusion that the homogeneity range is rather narrow (0≤ x 2.33− x V 4 O 11 average structure shows that this phase crystallizes in the monoclinic system, space group Cm with the cell parameters a =15.309(3); b =3.610(1); c =7.335(2) A; β =101.84(1)° with Z =4 unit formula. The detailed description of the structure is reported. The copper ions lie between [V 4 O 11 ] n layers built up of VO 6 octahedra. Cu ions exhibit non usual tetrahedral coordination and CN=3+2 polyhedra making the estimation of the electric balance between the couples Cu + Cu 2+ and V 4+ V 5+ difficult. A superstructure, which also exists at low temperature, is shown at room temperature by Bragg and Weissenberg diagrams. The homogeneity range of this VOB is discussed in light of its structural features.