High Temperature Mass Spectrometric Study of Thermodynamic Properties of the CaO ‐ SiO2 System

2006

Glass Phys Chem

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The possibility of calculating the thermodynamic properties of glasses and melts in the Cs 2 O-B 2 O 3 -SiO 2 system formed by two glass-former oxides and one modifier oxide with the use of the vacancy variant of the generalized lattice theory of associated solutions is demonstrated. A comparison with the experimental thermodynamic functions determined earlier by high-temperature differential mass spectrometry and electromotive force method shows that the calculations performed within this approach lead to reliable thermodynamic functions. The thermodynamic properties and structural features (the relative numbers of bonds with due regard for the second coordination sphere) of glasses and melts in the Cs 2 O-B 2 O 3 -SiO 2 system are analyzed in terms of the generalized lattice theory of associated solutions.

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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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

Plotnikov

2006

Glass Phys Chem

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“…Like the CaO-TiO 2 -SiO 2 system [14], the BaOTiO 2 -SiO 2 system at contents higher than 30 mol % SiO 2 is characterized by a positive deviation from ideal behavior (Fig. 2) due to the existence of phase separation regions both in the TiO 2 -SiO 2 binary system and in the BaO-TiO 2 -SiO 2 and CaO-TiO 2 -SiO 2 ternary systems.…”

Section: Discussionmentioning

confidence: 98%

Mass spectrometric study of the vaporization and thermodynamic properties of components in the BaO-TiO2-SiO2 system

Лопатин

2005

Glass Phys Chem

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The activities of silicon dioxide and barium oxide in the BaO-TiO 2 -SiO 2 system containing from 10 to 50 mol % SiO 2 at a mole fraction ratio BaO : TiO 2 = 1 and at a constant SiO 2 mole fraction of 0.5 are determined using high-temperature differential mass spectrometry. It is shown that the positive deviation of the SiO 2 activity and the negative deviation of the BaO activity from ideal behavior are observed at high SiO 2 contents.

High temperature mass spectrometric study of oxide systems and materials

Rapid Comm Mass Spectrometry

1993

High temperature mass spectrometry is a powerful tool for studying the vaporization processes and thermodynamic properties of different types of materials such as glasses, ceramics and coatings. This paper illustrates the main advantages of this method for investigations of oxide systems and the approaches available to predict the relative volatilities as well as the thermodynamic properties of materials based on these systems.The search for appropriate ways of obtaining new materials with required properties is closely associated with the progress made in the fields of energetics, metallurgy, and instrument and rocket making, as well as with the solution of problems of environmental protection. Most promising at present are oxide materials, which are characterized by superstrength, refractoriness and thermal stability. At high temperatures, however, the conditions of synthesis, study and use of materials are greatly complicated because of selective vaporization of components, leading to limited thermal stability. During the lase decade, as a result of further improvement of high temperature technologies, physico-chemical databanks have become widespread. Along with other properties, these databanks contain both thermodynamic functions of oxide systems and those of models which enable the thermodynamic properties of multicomponent oxide systems to be calculated. The results of experimental studies remain, as before, the only criterion of the validity and reliability of such calculations. Together with the electromotive force method and high-temperature calorimetric techniques, one of the most informative methods of high temperature chemistry is Knudsen effusion mass spectrometry. Within the framework of this method, it is possible not only to determine thermodynamic properties of components in condensed as well as gaseous phases, but also to determine vapour composition.The subject of the present Communication is oxide systems, which are the basis of glasses, glass-forming materials and slag melts, film materials, coatings and oxide ceramics. They include:(i) binary systems such as (NazO, CaO, B203, GeOz)-SiOz, Na20-B203, Na,O-GeO,, GeOz-P,05 and BaO-B203; (ii) ternary systems such as Na20-Bz03-Ge0,, B203-Ge02-Si0, and Ca0-A1203-Si02; (iii) multicomponent borosilicate glasses; (iv) coatings based on the B203-Si02 system with addi-(v) concrete; (vi) phosphate binder.The initiation of these studies was a very urgent requirement for meeting the needs of modern technologies in providing reliable information on vaporization processes and thermodynamic properties of oxide mat- erials. It is also necessary to find new semiempirical and statistical thermodynamic approaches in order to calculate the equilibria between condensed phase and vapour in oxide melts.The present work summarizes the available experimental data on vapour composition and thermodynamic properties of melts based on silica, boron, germanium and phosphorus oxides obtained by the author and her colleagues in the Institute of Silicate Chemistry of the Rus...