Electric conductivity of nanocluster polyoxomolybdates in the solid state and solutions

Abstract

The electric conductivity of nanocluster polyoxomolybdates (POMs) Mo132 and Mo72Fe30 with a keplerate structure in aqueous solutions, of these POMs in the solid state, and of Mo138 with a toroidal structure was studied. Data on the concentration dependence of the equivalent electric conductivity in solutions and on the specific conductivity of the solid samples were obtained. Solid Mo132 showed predominantly electron type of conductivity at nearly room temperatures due to the presence of molybdenum at different oxidation levels; Mo72Fe30, which has metal components at the highest oxidation levels, was found to be poor electric conductor; Mo138, which has a lower content of low-valence molybdenum than Mo132, showed intermediate conductivity and a reversible transition between the proton and electron types of conductivity.