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 O 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 O system.
Methods: The synthesis of the samples in the SrO-Al O 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 O , 3SrO·Al O , SrO·Al O , SrO·2Al O and SrO·6Al O 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 O system at high temperatures are characterized by negative deviation from ideality. The vaporization processes and thermodynamic properties of the SrO-Al O system were obtained for the first time.
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Mass spectrometric study and modeling of the thermodynamic properties of SrO-Al O melts at high temperatures.
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