Mass spectrometric study and modeling of the thermodynamic properties of SrO–Al₂O₃ melts at high temperatures

Abstract

Rationale The SrO–Al2O3 system holds promise as a base for a wide spectrum of advanced materials, which may be synthesized or applied at high temperatures. Therefore, studying vaporization and high‐temperature thermodynamic properties of this system is of great practical importance. Methods Samples of the SrO–Al2O3 system were obtained by solid‐state synthesis and identified by X‐ray fluorescence analysis, X‐ray phase analysis, scanning electron microscopy, electron probe microanalysis, simultaneous thermal analysis, and thermogravimetric analysis. The thermodynamic properties of the SrO–Al2O3 system were studied by the Knudsen effusion mass spectrometric (KEMS) method and were fitted by the Redlich–Kister and Wilson polynomials. The thermodynamic values obtained were also optimized within the generalized lattice theory of associated solutions (GLTAS). Results The vapor composition, temperature, and concentration dependences of the partial vapor pressures over the samples under study as well as the SrO activities in melts of the SrO–Al2O3 system were determined by the KEMS method. Usage of the Redlich–Kister and Wilson polynomials allowed calculation of the excess Gibbs energies, enthalpies of mixing, and excess entropies in the concentration range 0–33 mol% of SrO at temperatures of 2450 and 2550 K. Conclusions Significant negative deviations from the ideality were observed in the melts of the SrO–Al2O3 system at 2450, 2550, and 2650 K. The Wilson polynomial was found to be the optimal approach to describe the thermodynamic properties in the system studied. Optimization of the experimental data using the GLTAS approach allowed the characteristic features of the thermodynamic description of the SrO–Al2O3 system to be elucidated and explained.

Knudsen effusion mass spectrometry: Current and future approaches

“…It should be mentioned that, although not included in the reviews discussed earlier, recent experimental data obtained using KEMS at high temperatures on oxide systems and materials for nuclear applications such as the UO 2 ‐ZrO 2 , 67,210 Cs 2 O‐B 2 O 3 , 211 Cs 2 O‐MoO 3 , 212 and SrO‐Al 2 O 3 213,214 systems are available. Recent KEMS data on ceramics and glass ceramics with the special unique physicochemical properties such as the ZnO‐Nb 2 O 5 , 215 TiO 2 ‐Al 2 O 3 ‐SiO 2 , 216,217 and Al 2 O 3 ‐SiO 2 ‐ZrO 2 systems 218 as well as ultrahigh refractory ceramics based on the binary and multicomponent systems containing rare‐earth and hafnium oxides 219–221 have also been reported.…”