THERMODYNAMIC DATA AS TOOLS FOR INVESTIGATION OF DEFECT INTERACTIONS IN NONSTOICHIOMETRIC OXIDES - APPLICATION TO YBA2CU3O6+2X

Due to the recent availability of accurate measurements, the use of pa rtial molar quantities (free energy, enthalpy, and entropy) has emerge d as a tool aimed at evaluating effective pair interactions in non-sto ichiometric compounds. In the present paper, this approach has been us ed to ascertain the validity of inverse methods in a simple academic c ase and to discuss available thermodynamic data in the most extensivel y studied system, i.e., YBa2Cu3O6+2x, in the framework of asymmetric t wo-dimensional lattice-gas models proposed for this system.