Die modulierte Struktur von Cu x V4O11 (x = 2,12)

Abstract

Abstract The incommensurately modulated structure of the synthetic compound Cu2.12V4O11, Mr = 514.48, has been determined based on 8111 intensity data of 2763 main, 4863 1st-order and 485 2nd-order satellite reflections; R = 0.123, Rw = 0.041. For 5376 observed reflections, R = 0.042 and Rw = 0.039. The compound crystallizes monoclinic in the superspace group Cm(0, γ, 0) [γ = 0.2285(1)] with lattice Parameters a = 15.3004(2) Å, b = 3.60866(9) Å, c = 7.33566(9) Å, β = 101.851(1)°; V = 396.40(1) Å3, Z = 2, Dx = 4.310 Mgm−3. The double chains of edge-shared VO6 octahedra along [010] are connected through common corners and form layers V4O11 parallel to (001), between which the Cu ions are accomodated within two kinds of tunnels running parallel to [010]. While the tetrahedral Cu sites in one tunnel are occupied almost at random, the occupancies and y coordinates of those in the other tunnel are modulated in such a way, that the slight over-population of Cu ions may not cause short Cu–Cu distances. The positional modulation of V and O sites can be interpreted as a slight wavy deformation of the V4O11 layer as a whole.