Synthesis of Manganese Oxides via the Solution Combustion*

In recent years, manganese oxides (MnO2, Mn2O3, Mn3O4, MnO) have drawn the attention of many researchers due to their physicochemical properties and potential applications. Manganese dioxide, among manganese oxides, exists in several different polymorphs including α, β, γ, δ, λ-MnO2, which crystal structure determines many of its functional properties, including magnetic properties, electrochemical identification, molecular absorption, and properties. To date, various methods have been employed to synthesize these materials. This study proposes a method of solution combustion synthesis to synthesize manganese oxides in a single step. This study seeks to determine whether changes in fuel type, φ value, adiabatic temperature, and number of additives affect the stability of manganese oxide structure. The synthesized particles were then analyzed using X-ray diffraction and FE-SEM microstructural analysis. Studies have demonstrated that φ ˂ 1 and urea are the optimal conditions for the synthesis. Likewise, in order to determine the effects of heat treatment on the crystallinity of the synthesized particles in different conditions, heat treatment was carried out, which increased crystallinity in the samples. Despite the difficulty of synthesizing manganese oxides, particularly MnO2, the present study was able to perform it in a single step via solution combustion synthesis.