Heat capacity of stoichiometric Al2MnO4 spinel between 2 and 873 K

The heat capacity of stoichiometric Al2MnO4 spinel was measured from 2 to 873 K. These data are used to evaluate the entropy of this compound at 298.15 K and to propose a Gibbs energy function which was extrapolated to higher temperatures. Previously measured and assessed values for this compound are compared and the possible impact on the pseudo-binary Al2O3–MnO phase diagram is discussed. If it is assumed that all solid phases are stoichiometric and described by the compound energy model, and the liquid is described by the Kappor–Frohberg–Gaye quasi-chemical model, the proposed Gibbs energy model of the Al2MnO4 spinel corroborates the formation of two eutectic reactions in the Al2O3–MnO pseudo-binary phase diagram.

► Al2MnO4 was synthesized through reduction of oxide mixtures with graphite at 1273 K. ► The molar heat capacity of Al2MnO4 was measured between 2 and 300 K. ► The molar entropy of Al2MnO4 at 298.15 K was calculated and compared results in with earlier publications. ► The molar heat capacity of Al2MnO4 was measured between 323 and 873 K. ► A GG model is constructed, which gives support for the congruent melting of Al2MnO4.