Mass Spectrometric Study of the Thermodynamic Properties of Melts in the Cs2O-B2O3 System

Abstract

The vapor composition, activities of the components, and Gibbs energies of melts in the Cs 2 O-B 2 O 3 system at a temperature of 1020 K are determined by the Knudsen effusion mass spectrometric method. The activities of the components and the Gibbs energies of melts in the Cs 2 O-B 2 O 3 system at a temperature of 1020 are calculated in the framework of the approach based on the generalized lattice theory of associated solutions with the use of the melt model including vacancies. It is demonstrated that the calculated and experimental thermodynamic properties are in reasonable agreement.

Calculations of the thermodynamic properties of glasses and melts in the Cs2O-B2O3-SiO2 system in the framework of the generalized lattice theory of associated solutions

“…A number of the fitting parameters of the model were identical to those previously calculated for glasses and melts in the Na 2 O-SiO 2 , B 2 O 3 -SiO 2 [11], and Cs 2 O-B 2 O 3 [16] systems. When calculating the thermodynamic properties of glasses and melts in the Cs 2 O-B 2 O 3 -SiO 2 system with the use of the data taken from [4], the results of calculations can be compared with the experimental data only for the integral Gibbs energies ∆G given in [4].…”

“…In order to describe more adequately the structure of melts in the Cs 2 O-B 2 O 3 -SiO 2 system, a number of contact points in the [Cs 2 O] structural unit, as was done in [16,17] for melts in the Cs 2 O-B 2 O 3 , BaO-TiO 2 -SiO 2 , CaO-Al 2 O 3 -SiO 2 , and CaO-TiO 2 -SiO 2 systems, were taken to be vacant.…”

“…Table 1. Relative errors and root-mean-square deviations of the activities of Cs 2 O, B 2 O 3 , and SiO 2 in glasses and melts of the Cs 2 O-B 2 O 3 -SiO 2 system at 1020 K according to (2) the calculations within the generalized lattice theory of associated solutions in comparison with (1) the data obtained by high-temperature mass spectrometry [5] and the emf method [4] As regards a large error (the mean relative error is 70%) in determining the activities of components with the use of the approach under consideration for the Cs 2 O-B 2 O 3 system [16], this error is most likely associated with the limited amount of the data analyzed in [16]. [5] for 1200 K and (c-f) [4] for 1020 K.…”

Phase equilibria and thermodynamic properties of components in the Cs2O-B2O3-SiO2 system at high temperatures

“…The glasses in the Cs 2 O-B 2 O 3 -SiO 2 system were synthesized according to the procedure described in [10]. It should be noted that, for the Cs 2 O-B 2 O 3 -SiO 2 system, the glass formation region determined in our work was more extended than the glass formation region revealed in [3].…”

Specific features of the glass formation in the R 2O-B2O3, R 2O-SiO2, and R 2O-B2O3-SiO2 (R = Rb, Cs) systems

“…Investigation of the glass formation regions in the aforementioned systems is also important because of the necessity of solving the problems associated with the disposal of radioactive wastes in alkali borosilicate matrices. Some of the physicochemical properties of glasses of particular compositions in these systems were investigated in our previous works [2][3][4][5]. The glass formation in the binary systems can be judged from the relevant data included in the electronic information system [6], specifically from the sections concerned with the determination of the glass transition temperatures and densities of the R 2 O-B 2 O 3 and R 2 O − SiO 2 glasses existing in sufficient amounts.…”