Acentric Pseudo-Kagome Structures: The Solid Solution (Co1–xNix)3Sb4O6F6

Compounds within the solid solution (Co1–xNix)3Sb4O6F6 were prepared by the hydrothermal method. The compounds crystallize in the noncentrosymmetric cubic space group I 4̅3m with unit cell parameters a = 8.176(1) Å for M = Co and a = 8.0778(1) Å for M = Ni. The crystal structure is made up by corner sharing [MO2F4] octahedra via the fluorine atoms. [Sb4O6E4] supertetrahedra (T2) consisting of four [SbO3E] groups (E being the stereochemically active lone-pair on Sb) that share O atoms with the [MO2F2]n network. Magnetic ordering phenomena are observed with two characteristic temperatures, TN and T*, in the range from 67 to 170 K, that evolve gradually with composition and collapse for M = Co (x = 0) to one transition. TN is assigned to a transition into a long-range ordered antiferromagnetic phase, and T* marks a temperature in the range of 45 to 65 K where field cooled (FC) and zero field cooled (ZFC) susceptibility splits. The latter is tentatively attributed to a canting of the spin moments.