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

摘要

Compounds of the general formulae Fe3M2 (II)mo 2V3O20, where M = Ni, Co, Mn crystallizing in the monoclinic system have been obtained as a result of a solid-state reaction occurring between FeVO4 and M(II)oO(4) mixed at a molar ratio of 3:2. Temperatures of their incongruent melting amount to: Fe(3)A(2)Mo(2)V(3)O(20) -900 degrees C, Fe3CO2MO2V3O20-860 degrees C and Fe(3)Mn(2)NlO(2V3)O(20)-770 degrees C. In all of the nvestigated compounds, a wide EPR signal observed at g = 2 has been attributed to a spin-spin interaction of iron oxide or Fe3+ -Fe (3+) pairs. The analysis of the temperature dependence of the integral EPR intensity allows a determination of the values of exchange interaction constants. (c) 2007 Elsevier Ltd. All rights reserved.