Calculations of the Thermodynamic Properties of Glasses and Melts in the Na2O-SiO2 and B2O3-SiO2 Systems on the Basis of the Generalized Lattice Theory of Associated Solutions

Abstract

The possibility of calculating the thermodynamic properties of binary glass-forming systems containing both modifier (Na 2 O) and glass-former (B 2 O 3 ) oxides with the use of the vacancy variant of the generalized lattice theory of associated solutions is demonstrated for glasses and melts in the Na 2 O-SiO 2 and B 2 O 3 -SiO 2 systems.

Determination of Na2O activities in silicate melts by EMF measurements

“…Four main techniques are currently used to determine the thermodynamic activity of elements and/or oxide components in silicate liquids: (1) EMF measurements in galvanic cells [1][2][3], (2) vaporization processes such as Knudsen effusion mass spectroscopy [4][5][6][7], (3) chemical equilibration methods [8][9][10][11], (4) thermodynamic modelling of metal oxide -silica binary melts [12][13][14][15]. In this latter case, the systems explored are simple and the modelling generally concerns rationalization of available experimental data, rather than ab initio calculation of thermodynamic properties.…”

Simulation of the composition and proportions of anions in polymerized silicate melts

“…Each sequence is constructed to the complete saturation of bridging bonds in the formed polymer structure with due regard for the constraint that a given pair of monomers can be linked only by one bridging bond. For the polymer sequence involving unsaturated monomers, the probability of self-closure is given by relationship (4) and the probability of growth of the sequence of Q n particles (an increase in the polymer size) is defined by the expression (5) where is the probability of growth of the polymer sequence through a Q n monomer and the probability P n corresponds to the mole fraction of Q n structons in the initial system. Examples of a number of compositions of low-molecular species (including isomers) that can be constructed using the aforementioned statistical simulation are presented in Table 1.…”

“…When the first structon was an unsaturated Q n particle, the number of unsaturated bonds in the polymer chain was calculated and a random number was generated so that it took on one of the two values corresponding to the cyclization or attachment of a new Q n monomer. The probabilities of ring formation [expression (4)] and increase in the size of the polymer complex [relationship (5)] are equal to k/(nm + k) and nm/(nm + k), respectively. At the next stage, the pairs of unsaturated bonds closed inside the polymer and unsaturated bonds to which a new Q n particle was attached were simulated under the assumption that the probabilities of formation of bridging binds by any pair of unsaturated bonds of Q n structons are identical to each other.…”

“…The methods used for simulating these systems have been developed within the theory of associated solutions [2] and used to describe the mixing properties of metallurgically important oxide systems [3], as well as a number of alkali silicate and silicoborate systems (see, for example, [4,5]). However, one of the main problems associated with the practical use of the models under consideration is a correct choice of an optimum set of chemical compounds that can allow one to describe adequately the behavior of more complex systems involving different combinations of metal oxides and complex-forming components, in particular, SiO 2 and Al 2 O 3 .…”

Control of alkali-metal oxide activity in molten silicates

“…Next to thermodynamic modelling of metal oxide-silica binary melts [1,[6][7][8], several experimental attempts have been made to measure or control alkali-metal oxide activities in molten silicates at low pressure, such as EMF measurements in galvanic cells [9][10][11][12] or vaporization processes such as Knudsen effusion cells mass [13][14][15]. While very accurate, these techniques are however difficult to undertake due to the long-time acquisition experiments.…”