Subsolidus-Phase Equilibria in the System MgO-V2O5-MoO3

✍ Scribed by V.G. Zubkov; I.A. Leonidov; K.R. Poeppelmeier; V.L. Kozhevnikov

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 274 KB
• Volume: 111
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1994.1217

✦ Synopsis

The phase relations in the system (\mathrm{MgO}-\mathrm{V}{2} \mathrm{O}{5}-\mathrm{MoO}{3}) were studied and the subsolidus region of the phase diagram was constructed. The new compound (\mathrm{Mg}{2.5} \mathrm{VMoO}{8}) was discovered on the join of (\mathrm{MgMoO}{4}-\mathrm{Mg}{3} \mathrm{~V}{2} \mathrm{O}{8} . \quad \mathrm{Mg}{2.5} \mathrm{VMoO}{8}) crystallizes in the orthorhombic space group Pnma (No. 62) with cell dimensions (a=5.0515(1) \AA, b=10.3455(2) \AA, c=17.4683(4) \AA), and (Z=6). The structure is a framework of (\mathrm{MoO}{4}) and (\mathrm{VO}{4}) tetrahedra with linking octahedral and trigonal prismatic (\mathrm{MgO}{6}) groups. The molybdenum and vanadium cations preserve their highest oxidation state, and the electrical neutrality of the crystalline lattice is maintained by partial occupancy of magnesium sites. Simple quasibinary equilibria were established between (\mathrm{MgMoO}{4}) and (\mathrm{MoV}{2} \mathrm{O}{8}), (\mathrm{V}{2-x} \mathrm{Mo}{2 x} \mathrm{O}{5}, \mathrm{MgV}{2} \mathrm{O}{6}), and (\mathrm{Mg}{2} \mathrm{~V}{2} \mathrm{O}_{7}). 1994 Acadenic Press, Inc.