Hydrothermal Microwave Synthesis of MnO2 in the Presence of Melamine: The Role of Temperature and pH

Nanocrystalline manganese dioxide have been prepared by hydrothermal microwave treatment of mixed solutions of potassium permanganate and 2,4,6-triamino-1,3,5-triazine (melamine) in pH range 0.5–3. Phase and chemical composition and morphology of the samples was studied by XRD, Raman spectroscopy, and SEM. Conditions (solution pH and temperature) for the formation of single phase MnO 2 powders (α-MnO 2 , γ-MnO 2 , δ-MnO 2 , and δ*-MnO 2 ) under hydrothermal microwave treatment were determined.