Thermodynamic Modeling of Alkali Metal Oxide‐Silica Binary Melts

Abstract

The evaluation of the thermodynamic properties as well as the phase diagrams for the binary Na 2 O-SiO 2 , K 2 O-SiO 2 , and Li 2 O-SiO 2 systems are carried out with a structural model for silicate melts and glasses. This thermodynamic model is based on the assumption that each metallic oxide produces the depolymerization reaction of silica network with a characteristic free-energy change. A least squares optimization program permits all available thermodynamic and phase diagram data to be optimized simultaneously. In this manner, data for these binary systems have been analyzed and represented with a small number of parameters. The resulting equations represent the thermodynamic and phase diagram data for these alkali metal oxide-silica systems within experimental error limits. In particular, the measured limiting liquidus slope at X SiO2 ¼ 1 is well reproduced.

Combined X-Ray Diffraction and Absorption Study οf Crystalline Vanadium-Doped Lithium Disilicate

“…[27,28] in the Li 2 O-SiO 2 system) is scarce. This compound crystallises in Ccc2 space group (stable form [29]) or a metastable P bcn form [30,31].…”

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.…”

Application of the modified quasichemical model to solutions with strong short-range ordering

“…Using Eqs. (6), (15) and (18) Using Eq. (13) and the well-known property that lim x!0 xlnx = 0, the limit of the first derivative of F(T,y) with respect to T, as y !…”

“…Zaitsev et al [4] used the theory of associated solutions to describe the phase relations in this system, presuming the formation of silicon-oxygen groups of arbitrary sizes and spatial configurations [5]. Romero-Serrano et al [6] employed the structural model [7,8] for the liquid. Recently, the system has been optimized by Yazhenskikh et al [9] with the modified associate species model [10].…”