Summary: Subsolidus phase relations in the systems ZnWO₄-MnWO₄, ZnWO₄-ZnMoO₄, MnMoO₄-ZnMoO₄, and MnWO₄-MnMoO₄, were investigated by using the quenching technique. A complete series of solid solutions forms in the system ZnWO₄-MnWO₄ above 840° C, whereas limited solid solubilities were found in the other three. The various limits of solubility are, at 620° C, 4·0 mole % ZnMoO₄ in ZnWO₄ and 4·0 mole % ZnWO₄ in ZnMoO₄, 13·0 mole % ZnMoO₄ in MnMoO₄ and 12·0 mole % MnMoO₄ in ZnMoO₄, 9·0 mole % MnMoO₄ in MnWO₄ and 6·0 mole % in MnWO₄ in MnMoO₄; and at 1000° C, 15·0 mole % ZnMoO₄ in ZnWO₄ and 15·0 mole % ZnWO₄ in ZnMoO₄, 36·0 mole % ZnMoO₄ in MnMoO₄ and 29·0 mole % MnMoO₄ in ZnMoO₄, 15·0 mole % MnMoO₄ in MnWO₄ and 27·0 mole % MnWO₄ in MnMoO₄.

Subsolidus phase relations in the system ZnWO₄-ZnMoO₄-MnWO₄-MnMoO₄ were studied at 900° C. The solubility of molybdenum in the (Zn,Mn)WO₄ series increases from both end members to a maximum of 27·0 mole % at the composition Mn₃₅Zn₆₅. Both molybdates also have limited ranges of solid solutions, and a three-phase region occupies the central portion of the system defined by three points with compositions of 41 mole % ZnMoO₄, 26 mole % MnMoO₄, 33 mole % MnWO₄; 57 mole % ZnMoO₄, 10 mole % MnMoO₄, 35 mole % MnWO₄; and 27 mole % ZnMoO₄, 34 mole % MnWO₄, 39 mole % ZnWO₄.