Crystal Structure of a New Form of Cu3V2O8

Abstract

A new form of Cu3V2O8 was prepared at 30 kbar and 900 °C. The unit cell has dimensions a = 6.2493(9), b = 7.9936(9), c = 6.3776(10) Å, β = 111.49(1)°, and the space group is P2/c. The crystal structure, refined by least-squares to a final R = 0.054, using 848 reflections, is similar to that of Mg3V2O8. Chains of edge-shared M2 octahedra run along the c axis at about y = ± 1/4 with M1 octahedra sharing two edges with the M2 octahedra. These octahedral networks at about y = ± 1/4 are linked by corner-shared V–O tetrahedra. The distortion from the Mg3V2O8 structure can be explained on the basis of the Jahn–Teller effect in which four of the octahedral Cu—O distances shorten to 1.93–1.99 Å and two Cu—O distances lengthen to 2.3–2.6 Å.