Reactivity of FeVO4 towards selected molybdates(VI) of divalent transition metals Original Research Article

Compounds of the general formulae Fe3M2View the MathML sourceMo2IIV3O20, where M=NiM=Ni, Co, Mn crystallizing in the monoclinic system have been obtained as a result of a solid-state reaction occurring between FeVO4 and MView the MathML sourceMoO4II mixed at a molar ratio of 3:2. Temperatures of their incongruent melting amount to: Fe3Ni2Mo2V3O20—900 °C, Fe3Co2Mo2V3O20—860 °C and Fe3Mn2Mo2V3O20—770 °C. In all of the investigated compounds, a wide EPR signal observed at g=2g=2 has been attributed to a spin–spin interaction of iron oxide or Fe3+–Fe3+ pairs. The analysis of the temperature dependence of the integral EPR intensity allows a determination of the values of exchange interaction constants.