Acentric Pseudo-Kagome Structures: The Solid Solution (Co 1– x Ni x ) 3 Sb 4 O 6 F 6

Compounds within the solid solution (Co 1– x Ni x ) 3 Sb 4 O 6 F 6 were prepared by the hydrothermal method. The compounds crystallize in the noncentrosymmetric cubic space group I 4̅3 m 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 [MO 2 F 4 ] octahedra via the fluorine atoms. [Sb 4 O 6 E 4 ] supertetrahedra (T2) consisting of four [SbO 3 E] groups (E being the stereochemically active lone-pair on Sb) that share O atoms with the [MO 2 F 2 ] n network. Magnetic ordering phenomena are observed with two characteristic temperatures, T N 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. T N 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.