Synthesis and crystal structure of the high-pressure cobalt borate HP-CoB2O4

Abstract

The cobalt borate HP-CoB2O4 was synthesized from Co3O4 and B2O3 under high-pressure / high-temperature conditions of 6.5 GPa and 950 °C. The structure of HP-CoB2O4 is isotypic to HPNiB2O4 and β-FeB2O4, representing the third example of a borate, in which every BO4 tetrahedron shares a common edge with a second one. HP-CoB2O4 crystallizes in the space group C2/c (Z = 4) with the parameters a = 934.6(2), b = 562.0(2), c = 443.3(1) pm, β = 108.2(1)°, V = 0.2212(1) nm3, R1 = 0.0218, and wR2 = 0.0410 (all data). The structure consists of layers of BO 4 tetrahedra, that are interconnected via strings of edge-sharing FeO6 octahedra. © 2010 Verlag der Zeitschrift für Naturforschung, Tübingen.