Crystal structure refinement of magnesium zinc divanadate, MgZnVO, from powder X-ray diffraction data.

The crystal structure of magnesium zinc divanadate, MgZnVO, was determined and refined from laboratory X-ray powder diffraction data. The title compound was synthesized by a solid-state reaction at 1023 K in air. The crystal structure is isotypic with MnZnVO (/; = 6) and is related to the crystal structure of thortveitite. The asymmetric unit contains two metal sites with statistically distributed magnesium and zinc atoms with the atomic ratio close to 1:1. One (Mg/Zn) metal site (1) is located on Wyckoff position 8 and the other (2) on 4. Three V sites (all on 4), and eight O (three 8, four 4, and one 2) sites complete the asymmetric unit. The structure is an alternate stacking of VO layers and (Mg/Zn) atom layers along [20]. It is distinct from other related structures in that each VO layer consists of two groups: a VO dimer and a VO tetra-mer. Mixed-occupied 1 and 2 are coordinated by oxygen atoms in distorted trigonal bipyramidal and octa-hedral sites, respectively.