Thermodynamic properties and phase equilibria in the MnO-SiO{sub 2} system
- Inst. of Physical Metallurgy, Moscow (Russian Federation). Lab. of Thermodynamic Investigations
The Knudsen effusion technique with mass-spectrometric analysis of evaporated products has been applied for determination of thermodynamic properties of solid and liquid phases in the MnO-SiO{sub 2} system. To bring about volatile substances with measurable pressures, reduction reactions of MnO-SiO{sub 2} with molybdenum or niobium were conducted in effusion cells. Activities of the components have been calculated by several methods. The results coincided within the experimental error limits (2--3%). The following equations have been found for Gibbs energies of formation of the compounds MS and M{sub 2}S (M = MnO, S = SiO{sub 2}): {Delta}{sub f}G(MS) = {minus}(10,090 {+-} 616) {minus} (0.81 {+-} 0.42)T, J/mol (1,369 < T < 1,525 K) and {Delta}{sub f}G(M{sub 2}S) = {minus}(11,560 {+-} 588) {minus} (1.30 {+-} 0.38)T, J/mol (1,388 < T < 1,585 K). Temperature and concentration dependencies of {alpha}{sub MnO} and {alpha}{sub SiO{sub 2}} in liquid solutions have been described by the associated-solution model. Formation of associative complexes MnO-SiO{sub 2} and 2MnO-SiO{sub 2} as well as polymer SiO{sub 2} networks was taken into account. Thermodynamic computation of the phase diagram was carried out.
- OSTI ID:
- 218641
- Report Number(s):
- CONF-940468-; ISSN 1080-1278; TRN: IM9619%%362
- Journal Information:
- High Temperature and Materials Science, Vol. 34, Issue 1-3; Conference: 8. international conference on high temperature materials chemistry, Vienna (Austria), 4-9 Apr 1994; Other Information: PBD: Aug-Dec 1995
- Country of Publication:
- United States
- Language:
- English
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