Vaporization and thermodynamic properties of the SrO‐Al <sub>2</sub> O <sub>3</sub> system studied by Knudsen effusion mass spectrometry
С. И. Лопатин, С. М. Шугуров, Natalia G. Tyurnina, Z. G. Tyurnina, I. G. Polyakova, E. A. Balabanova
Abstract
Rationale Strontium aluminates can be used as refractory construction materials at temperatures up to 2000 ° С or as the materials for immobilization of long‐lived radioactive waste. The SrО‐Al 2 O 3 system is one of the more complicated oxide systems used for the creation of new radio‐transparent materials. The exploitation of such materials at high temperatures demands the knowledge of the thermal stability of the compounds and solid solutions formed in the SrО‐Al 2 O 3 system. Methods The synthesis of the samples in the SrO‐Al 2 O 3 system was carried out by a ceramic method at 1250°C. The characterization of the samples was accomplished with the use of X‐ray diffraction (XRD). The vaporization of the samples under study was performed from a twin tungsten effusion cell using the Knudsen effusion mass spectrometry method. Results The temperature dependences of partial pressures of vapor species over 4SrO·Al 2 O 3 , 3SrO·Al 2 O 3 , SrO·Al 2 O 3 , SrO·2Al 2 O 3 and SrO·6Al 2 O 3 in a wide range of temperatures were determined. The component activities, the Gibbs energies of mixing and the standard enthalpies of individual strontium aluminates were obtained. Conclusions The thermodynamic properties of the SrO‐Al 2 O 3 system at high temperatures are characterized by negative deviation from ideality. The vaporization processes and thermodynamic properties of the SrO‐Al 2 O 3 system were obtained for the first time.