The phase diagram calcite-aragonite as derived from the crystallographic properties

A general method to calculate phase diagrams from the fundamental crystallographic properties has been suggested, using the calcite-aragonite reaction as an example. This procedure requires the measurement of the phonon spectra at different temperatures and pressures, calculation of a reasonable Grüneisen parameter to obtain Cp values from the Cv values and the consideration of the order—disorder phenomena and its contribution to the Gibb's energy. The remarkable agreement seen between the calculated diagram and that determined experimentally speaks for the reliability of this method.

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