An internally consistent thermodynamic data set has been derived utilizing results from all available experimental phase equilibria in a simultaneous iterative regression approach using 1/T vs. ln Kred plots. Simultaneous evaluation of all reactions allows the extraction of an internally consistent data set of ΔfH° (enthalpy of formation of the elements) and S°(third law entropy) values with V° (molar volume), cp (heat capacity), α and β (thermal expansion and compressibility) otherwise constrained.
An objective function has been defined which requires maximum consistency with available experimental results and minimum deviation from available calorimetric data. One advantage of this procedure is that all available experimental results, compatible or not, are always visible during the calculations.
Over 5300 experimental results from 244 contributions for 253 reactions involving 94 phase components have been used initally and is since growing. The extracted data set reproduces 92% of the available phase equilibria experiments reported in the literature.
Fundamental to this dataset is the minimum use of mixing models. When ever possible phase equilibria involving only pure phases were used. The derived dataset should therfore represent good values for the pure phase components.
The data set presented here has been published under the title:
Gottschalk, M. (1997): Internally consistent thermodynamic
data for minerals in the system SiO2-TiO2-Al2O3-Fe2O3-CaO-MgO-FeO-K2O-Na2O-H2O-CO2.
European Journal of Mineralogy, 9, 175-223.
In this paper, it was not possible to publish all material. On this this web-site, all 1/T vs. ln Kred plots for all reactions are accesible and can be downloaded as postcript-files. The derived ΔfH° and S° values as well the thermophysical constants und functions used can be also downloaded in various formats.
In addition, corrections and addition will be made public here. In future, Mathematica(TM) functions for thermodynamic calculations will be made available as packages as well as input files for Theriak and TWQ. PERPLEX is already adapted.
Such a thermodynamic data base is never finished. Therefore comments, suggestions, corrections, references to phase equilibria and thermophysical data are wellcome and will be incorporated in future versions.
For contact :
Section 3.3: Chemistry and Physics of Earth Materials