Mass spectrometric investigation of vaporization in the Bi2O3-Fe2O3 system

The thermodynamics of vaporization in the Bi2O3-Fe2O3 quasibinary system was studied by high-temperature mass-spectrometry. The partial pressures of the constituents of a saturated vapor over the system at 1100 K were determined. Based on the experimental data, the following parameters were calculated: the activities of the components of the Bi2O3-Fe2O3 system condensed phase, the standard enthalpies of some heterogeneous reactions, and standard enthalpies of formation and enthalpies of formation for crystalline BiFeO3 and Bi2Fe4O9 from individual oxides. An optimal temperature for the solid-phase synthesis of bismuth ferrites from simple oxides is recommended.