The X-ray and bulk densities of PdIn alloys were determined at ambient temperature on samples annealed at 1273 and 1373K and quenched in water-ice mixtures. From these measurements the vacancy concentrations in this intermetallic phase were obtained as a function of In concentration at these 2 temperatures. In addition, a generalized thermodynamic model was presented which considers the existence of antisite and vacancy defects on both sub-lattices without any dilute solution approximations. This model used three energy parameters, whose values were obtained for PdIn using the measured vacancy concentrations and the chemical potentials of In. This model was able to describe all of the available vacancy data and was suitable for calculating these values at compositions and temperatures when such data were not available. In addition, the model permits the calculation of the concentrations of the minority point defects. It was shown that dilute-solution approximations, which had invariably been used in this kind of modelling, were unsatisfactory. The present results and their analysis confirmed that PdIn was a near-triple-defect type of intermetallic and not a near-Schottky type, as had been claimed.

Thermodynamics and Point Defects in the B2 Intermetallic Phase PdIn. M.Huang, W.A.Oates, Y.A.Chang: Philosophical Magazine, 2003, 83[5], 589-601