Magnetization studies of chemically prepared manganese dioxides

A study is made of the magnetization properties of commercial, chemically prepared, manganese dioxides which are intended for use in dry cells, zinc alkaline cells and magnesium cells. The technique employs a vibrating sample magnetometer and the properties are measured as a function of applied fields at room temperature. A correlation is found between the shift of the (411) XRD peak and the magnetization behaviour. The results indicate that the magnetizability that is observed in these mostly alpha-phase containing samples can be accounted for by the average Mn-Mn distance and the consequent interactions between manganese spins mediated by O2- and OH-. Of particular interest to magnetic moments of MnO2 samples with traces of delta phases is the prediction that the extent of the modification of the birnessite phase has a significant influence. (C) 1998 Elsevier Science S.A. All rights reserved.