Thermochemistry of Pd-In, Pd-Sn and Pd-Zn alloy systems

The standard enthalpy of formation of several Pd-M alloys (M= In, Sn and Zn) has been measured using a high temperature direct drop calorimeter. The reliability of the calorimetric results has been determined and supported by using different analytical techniques: light optical microscopy, scanning electron microscopy equipped with electron probe microanalysis (EPMA with EDS detector) and X-ray powder diffraction analysis. The values of fH (kJ/mol atoms) for the following phases were obtained for the formation in the solid state at 300 K: PdIn (49 at.%In): −69.0±1.0; Pd2In3 −57.0±1.0; Pd3In7: −43.0±1.0; PdSn2: −50.0±1.0; Pd2Zn9 (77 at.%Zn): −33.7±1.0; Pd2Zn9 (78 at.%Zn): −34.0±1.0; Pd2Zn9 (80 at.%Zn): −35.0±1.0. The results show exothermic values which increase from the Pd-Zn to the Pd-Sn and Pd-In systems; the data obtained have been discussed in comparison with those available in literature.