Thermal characterization of chemically reduced electrolytic manganese dioxide

Samples of electrolytic manganese dioxide (EMD) were chemically reduced using 2-propanol under reflux (82 degrees C) for 1, 2, 3, 6 and 24 h intervals. XRD analysis showed that the gamma-MnO2 structure was preserved although the lattice dimensions were observed to increase with increasing degree of reduction to accommodate the intercalation of protons. The exception was the 24 h reduced sample which contained two phases; gamma-MnO2 and gamma-MnOOH. Three regions of decomposition in the range of 50 to 1000 degrees C were observed using thermogravimetric analysis coupled with mass spectrometry (TG-MS) and were accounted for as water removal below 390 degrees C, reduction of MnO2 to Mn2O3 between 400 and 600 degrees C, and Mn2O3 to Mn3O4 between 600 and 1000 degrees C. Again the exception proved to be the 24 h reduced sample which was observed to decompose predominantly in one step between 400 and 600 degrees C directly to Mn3O4.