Energetics of manganese oxides

S. Fritsch, A. Navrotsky

Research output: Contribution to journalConference articlepeer-review


The energetics of some manganese oxides: pyrolusite MnO2, bixbyite Mn2O3, hausmannite Mn3O4 and manganosite MnO were studied by transposed temperature drop calorimetry and high temperature drop solution calorimetry in molten 2PbO·B2O3 at 977 K. The enthalpies of oxidation at 298 K in the Mn-O system, determined by appropriate thermodynamic cycles, are (in kJ/mol O2): -441.4 ±5.8 for the reaction 6 MnO + O2 → 2 Mn3O4, -201.8 ± 8.7 for 4 Mn3O4 + O2 → 6 Mn2O3 and -162.1 ± 7.2 for 2 Mn2O3 + O2 → 4 MnO2. These values agree very well with previous data obtained by equilibrium pO2 measurements and indicate that direct calorimetric measurements are well suited to obtain reliable enthalpy of formation data for oxides containing manganese in the 2+, 3+ and 4+ states. The phase diagram of the Mn-O system was calculated using these new values of enthalpies.

Original languageEnglish (US)
Pages (from-to)667-672
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
StatePublished - 1996
Externally publishedYes
EventProceedings of the 1995 MRS Fall Meeting - Boston, MA, USA
Duration: Nov 26 1995Dec 1 1995

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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