Abstract
Co5V2(P2O7)4 was crystallized by chemical vapour transport using HCl as transport agent. Its crystal structure is isotypic to that of Fe(II) 5Fe(III) 2(P2O7)4 and can be regarded as a member of the thortveitite structure family with corrugated layers of metal-oxygen polyhedra extending parallel to (010). Significant occupational disorder between cobalt(II) and vanadium(III) is observed. Four of the five cation sites are occupied by both cobalt and vanadium. The fifth cation site (Co1) is occupied by cobalt only. Sites Co1, M3 and M4 are located on twofold axes. Sites Co1, M2, M3 and M4 show o-cta-hedral coordination by oxygen; M5 has a square-pyramidal environment.