thumbnail

Thermodynamics of open networks: Ordering and entropy in NaAlSiO4 glass, liquid, and polymorphs

Physics and Chemistry of Minerals

By:
, , , , , and
DOI: 10.1007/BF00212206

Links

Abstract

The thermodynamic properties of carnegieite and NaAlSiO4 glass and liquid have been investigated through Cp determinations from 10 to 1800 K and solution-calorimetry measurements. The relative entropies S298-S0 of carnegieite and NaAlSiO4 glass are 118.7 and 124.8 J/mol K, respectively. The low-high carnegieite transition has been observed at 966 K with an enthalpy of transition of 8.1??0.3 kJ/mol, and the enthalpy of fusion of carnegieite at the congruent melting point of 1799 K is 21.7??3 kJ/mol. These results are consistent with the reported temperature of the nepheline-carnegieite transition and available thermodynamic data for nepheline. The entropy of quenched NaAlSiO4 glass at 0 K is 9.7??2 J/mol K and indicates considerable ordering among AlO4 and SiO4 tetrahedra. In the liquid state, progressive, temperature-induced Si, Al disordering could account for the high configurational heat capacity. Finally, the differences between the entropies and heat capacities of nepheline and carnegieite do not seem to conform to current polyhedral modeling of these properties ?? 1990 Springer-Verlag.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Thermodynamics of open networks: Ordering and entropy in NaAlSiO4 glass, liquid, and polymorphs
Series title:
Physics and Chemistry of Minerals
DOI:
10.1007/BF00212206
Volume
17
Issue:
5
Year Published:
1990
Language:
English
Publisher location:
Springer-Verlag
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Physics and Chemistry of Minerals
First page:
385
Last page:
394
Number of Pages:
10