THE BAYESIAN-APPROACH TO AN INTERNALLY CONSISTENT THERMODYNAMIC DATABASE - THEORY, DATABASE, AND GENERATION OF PHASE-DIAGRAMS

An internally consistent thermodynamic dataset has been derived for 14 8 endmember phases (145 solids and 3 fluids) comprising the elements L i, Na, K, Be, Mg, Ca, Ti, Cr, Mn, Fe, Zn, Al, Si, C, H, and O. This ha s been achieved by simultaneous treatment of phase property (like stan dard enthalpy of formation, standard entropy, molar heat capacity, mol ar volume, thermal expansivity, bulk modulus etc.) and reaction revers al data by the Bayesian method. The theory underlying the approach, an d the computational methods involved, are briefly outlined. (For the b enefit of readers unfamiliar with inference statistics, the basic conc epts of the Bayes method are also presented in such a way that they ca n be grasped intuitively.) Although not yet addressed, this method can be extended to refine the thermodynamic mixing properties of crystall ine solutions. The sources of the input data, culled from the literatu re, are summarized in the Appendix. The resulting database is succinct ly documented in this paper. It includes the enthalpies of formation a nd entropies, their uncertainties, and the correlation among them. The database allows calculation of P-T, T-X-CO2, P-X-CO2, and T-f(O2) sec tions, with error propagation into the computed phase diagrams on a ro utine basis. A user-friendly computer program has been written to gene rate such phase diagrams. It is public domain software. The software a nd the thermodynamic database (which includes a complete documentation of the thermodynamic data above and beyond those listed (Table 2, her e) may be downloaded from the web site ruhr-uni-bochum.de/niranjan.cha tter-jee/Index.htm. Examples of computed phase diagrams are given to i llustrate the quality of the data and the capabilities of the software .