High-temperature thermodynamic properties of the Al2O3-SiO2 system

Abstract

High-temperature mass spectrometry is used to investigate vaporization processes and determine SiO 2 activity in the Al 2 O 3 -SiO 2 system between 1850 and 1970 K. The results are consistent with the known phase equilibria in this system.

Mass spectrometric investigation of the vaporization and thermodynamic properties of components in the BaO-SiO2 system

“…The ionizing efficiency curves for the above ions do not exhibit kinks. The appearance energies of the SiO + , BaO + , Ba + , Mo , Mo , and BaMo ions within the limits of experimental error coincide with the ionization energies of the relevant molecules [3,4,8]. Therefore, the inference can be made that the SiO + , BaO + , Ba + , Mo , Mo , and BaMo ions are products of direct ionization of the corresponding molecules.…”

“…The vaporization of silicon dioxide was studied in detail by Bondar' et al [4]. It was demonstrated that, when evaporating from a molybdenum cell at temperatures in the range 1800-1990 K, silicon dioxide turned into a gaseous phase with virtually complete dissociation into silicon monoxide and oxygen and an insignificant portion of the silicon dioxide undergoes sublimation without a decomposition.…”

“…It was demonstrated that, when evaporating from a molybdenum cell at temperatures in the range 1800-1990 K, silicon dioxide turned into a gaseous phase with virtually complete dissociation into silicon monoxide and oxygen and an insignificant portion of the silicon dioxide undergoes sublimation without a decomposition. The presence of the MoO 3 and MoO 2 gaseous molybdenum oxides in the vapor over SiO 2 was associated with the interaction of the sample under investigation with the cell material (Mo) [4]. The temperature dependence of the SiO vapor partial pressure over the pure silicon oxide in the above temperature range was described by the relationship [4] (1) When evaporating barium oxide from a molybdenum cell at temperatures in the range 1838-1970 K [5], it was revealed that the vapor consists of a mixture of barium oxide, atomic barium, and oxygen.…”

“…The presence of the MoO 3 and MoO 2 gaseous molybdenum oxides in the vapor over SiO 2 was associated with the interaction of the sample under investigation with the cell material (Mo) [4]. The temperature dependence of the SiO vapor partial pressure over the pure silicon oxide in the above temperature range was described by the relationship [4] (1) When evaporating barium oxide from a molybdenum cell at temperatures in the range 1838-1970 K [5], it was revealed that the vapor consists of a mixture of barium oxide, atomic barium, and oxygen. The relative content of atomic barium increases with an increase in the temperature.…”

High Temperature Mass Spectrometric Study of Thermodynamic Properties and Vaporization Processes of Oxide Systems: Experiment and Modeling

“…The advantages of application of the Belton-Fruehan method to study the thermodynamic functions of oxide systems were illustrated in details in [38]. The correlation of thermodynamic properties obtained by high temperature mass spectrometry with the information on phase diagrams of the system studied was shown for example in the following systems CaO-SiO 2 [39] [42][43][44] and MgO-SiO 2 [45].…”