Thermochemical and thermodynamical properties of HTSC phases are revie
wed for the Y-Ba-Cu-O system and also presented for the newly calculat
ed Bi-Sr-Cu-O system stressing out stoichiometric and phenomenological
viewpoints. Simulated data are listed for (H-298(0)-H-0(0)), phase tr
ansformation temperatures, standard entropies, standard enthalpies of
formation, heat capacities in crystalline phase, etc. Pseudobinary pha
se diagrams are treated showing the effect of oxygen partial pressure
particularly illustrated on the (Sr, Pi, Ba)-Cu-O system.