Vaporization and Thermodynamic Properties of the SrO–BaO–Al2O3–SiO2 System Based on High-Temperature Mass Spectrometry Data

The vaporization processes and thermodynamic properties of the SrxBa1 – xAl2Si2O8 (x = 0.1–0.9 in increments of 0.1) system are studied for the first time using high-temperature mass spectrometry (HTMS) at a temperature of 2000 K. The samples are synthesized by the solid-state synthesis method at a temperature of 1623 K with isothermal holding for 5–10 h. The single-phase state and celsian-type structure are confirmed by powder X-ray diffraction data and Rietveld refinement using the MAUD software. Partial pressures of Sr, Ba, BaO, SiO, and O2 are determined, together with the activities of SrO, BaO, and SiO2 in the condensed phase, as well as the Gibbs energy of mixing (ΔG) and excess Gibbs energy (ΔG E). A negative deviation from ideal behavior is found across the entire composition range, with a minimum in ΔG at x = 0.4 in SrxBa1 – xAl2Si2O8. The obtained results are important for the development of heat-resistant, radio-transparent ceramics based on the (Sr,Ba)Al2Si2O8 system.