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

Abstract

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 Δ f H (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; Pd 2In 3 −57.0 ± 1.0; Pd 3In 7: −43.0 ± 1.0; PdSn 2: −50.0 ± 1.0; Pd 2Zn 9 (77 at.%Zn): −33.7 ± 1.0; Pd 2Zn 9 (78 at.%Zn): −34.0 ± 1.0; Pd 2Zn 9 (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.