High‐temperature mass spectrometric study of thermodynamic properties in the TiO₂–Al₂O₃–SiO₂ system and modeling

Abstract

Rationale The TiO2–Al2O3–SiO2 system is the base for various glass–ceramic materials, which have great practical value for a large number of modern technologies. Many TiO2–Al2O3–SiO2 materials are synthesized or applied at high temperatures, which justifies the relevance of the present study. Methods The samples in the TiO2–Al2O3–SiO2 system were synthesized using the method of induction melting in a cold crucible. The thermodynamic properties of the TiO2–Al2O3–SiO2 system were studied using the Knudsen effusion mass spectrometric method. The derived thermodynamic functions were optimized within the generalized lattice theory of associated solutions (GLTAS) approach and compared with the results of calculation using the semiempirical Kohler, Muggianu, Toop, Redlich–Kister, and Wilson methods based on the corresponding data in the binary systems. Results The SiO2 selective vaporization from the samples under study was shown at temperatures above 1940 K. The thermodynamic properties in the TiO2–Al2O3–SiO2 system, including the TiO2–SiO2 system, were obtained in the temperature range 1965–2012 K and were optimized using GLTAS to obtain the consistent concentration dependences of the component activities and excess Gibbs energies. Conclusions Positive deviations from the ideal behavior were observed in the TiO2–Al2O3–SiO2 system at high temperatures. Comparison of these values with the results of the modeling based on the GLTAS approach allowed the recommendations regarding the optimal semiempirical methods for the excess Gibbs energy calculation in different concentration ranges to be made.

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. It is necessary to emphasize that the thermodynamic properties obtained in all these systems were discussed within the framework of semiempirical and statistical thermodynamic approaches for modeling and prediction of thermodynamic properties of multicomponent systems based on the corresponding data on binary systems.…”