PHASE TRANSITIONS IN THE IRON-OXYGEN SYSTEM AND THEIR THERMODYNAMIC PROPERTIES

Using the example of the Fe-O system, the expediency of writing chemical formulas per mole of atoms of the compound is shown. This approach allowed us to balance phase transition reactions, using the level rule, to compare the thermodynamic properties of compounds and to conduct thermodynamic calculations of the reactions of wüstite decomposition and the formation of hematite by oxidizing magnetite with oxygen. Magnetite Fe0,429O0,571 is characterized by more negative values of Gibbs free energy of formation in comparison with hematite Fe0,400O0,600 in the temperature range of 1000–1800 K.