Abstract
The crystal structure of magnesium zinc divanadate, MgZnV2O7, 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 Mn0.6Zn1.4V2O7 (C2/m; Z = 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 (M1) is located on Wyckoff position 8j and the other (M2) on 4h. Three V sites (all on 4i), and eight O (three 8j, four 4i, and one 2b) sites complete the asymmetric unit. The structure is an alternate stacking of V2O7 layers and (Mg/Zn) atom layers along [20]. It is distinct from other related structures in that each V2O7 layer consists of two groups: a V2O7 dimer and a V4O14 tetra-mer. Mixed-occupied M1 and M2 are coordinated by oxygen atoms in distorted trigonal bipyramidal and octa-hedral sites, respectively.
Highlights
Mixed vanadium oxides with tetrahedrally coordinated pentavalent vanadium ions have been used as catalysts in the heterogeneous oxidation process (Chang & Wang, 1988)
During the course of studying the phase diagram in the MgO–ZnO–V2O5 system, a new phase was identified by its X-ray diffraction pattern in the solid-solution range between (Mg0.80Zn1.20)V2O7 and (Mg1.16Zn0.84)V2O7, which was completely different from Mg2V2O7 or Zn2V2O7 (Chang & Wang, 1988)
We present here the crystal structure of MgZnV2O7 (Fig. 1), as determined and refined from laboratory powder X-ray diffraction data (Table 1)
Summary
Mixed vanadium oxides with tetrahedrally coordinated pentavalent vanadium ions have been used as catalysts in the heterogeneous oxidation process (Chang & Wang, 1988). Since there is a strong correlation between the crystal structure and its properties, the phase relations of vanadates have been thoroughly investigated. During the course of studying the phase diagram in the MgO–ZnO–V2O5 system, a new phase was identified by its X-ray diffraction pattern in the solid-solution range between (Mg0.80Zn1.20)V2O7 and (Mg1.16Zn0.84)V2O7, which was completely different from Mg2V2O7 or Zn2V2O7 (Chang & Wang, 1988). The crystal structure of the new phase has not been reported to date. We present here the crystal structure of MgZnV2O7 (Fig. 1), as determined and refined from laboratory powder X-ray diffraction data (Table 1)
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