Crystallization and Structures of Novel R₂O₃-MoO₃ (R=rare earth) Compounds

Abstract

Thermal decomposition of rare earth (R) polyoxomolybdate [R₂(H₂O)₁₂Mo₈O₂₇]·nH₂O at 700-800°C in air has been carried out. Four compounds of R₂Mo₅O₁₈, R₆Mo₁₂O₄₅, R₄Mo₇O₂₇, and R₆Mo₁₀O₃₉ have been obtained for R=Gd. All these products are novel compounds which have not appeared in the phase diagram of the Gd₂O₃-MoO₃ system. X-ray structural analysis showed that these compounds consist of MoO₄ tetrahedra, MoO₅ trigonal bipyramids, MoO₆ octahedra, and RO₇ and RO₈ polyhedra.