Pb₃Mn₇O₁₅: synthesis, phase transition, transformation and decomposition

Pb₃Mn₇O₁₅ was synthesized from MnO₂ and PbO via solid-state reaction and the phase transition were discussed systematically. Powder X-ray diffraction, SEM and EDS were used to characterize the samples. The results show that the optimized temperature is 850 ℃ and PbO overdose amount is 5 % for Pb₃Mn₇O₁₅ synthesis. The phase transition between orthorhombic and hexagonal Pb₃Mn₇O₁₅ 100~200 ℃ is reversible. The metastable phase Pb₄Mn₉O₂₀ decomposed into Pb₃Mn₇O₁₅ at 800~850 ℃ irreversibly. Further temperature increase at 950℃ to 1 000 ℃ leads to the decomposition of Pb₃Mn₇O₁₅. The final product contains crystalline Mn₃O₄ spinel and non-crystallized PbO.