Reduction-reoxidation behavior of manganese cation-deficient spinels

Thermogravimetry and electrical conductivity were used to study the reduction-reoxidation behavior of submicronic manganese-cation-deficient spinels. The aim is to control the hydrogen reduction of a number of Fe³⁺ ions in partially oxidized spinels at room temperature so that an “original state” can be obtained. In more oxidized spinels at 400°C, the availability for reduction of Fe³⁺ ions is much less than that of Mn³⁺ ions in octahedral sites. The reduced phase could be reoxidized to the original oxygen level and further oxidation-reduction cycles resulted in no change in cation distribution but were accompanied by sintering.