HYDROGEN SPECTROSCOPY OF PD1-]YAGY AND PD1-]YCUY ALLOYS

Thermodynamic data for hydrogen absorption in Pd1-yAg y and Pd1-yCuy alloys, including pressure-composition isotherms and enthalpies and excess entropies of solution, are described by a multi-site lattice gas model. The distributions of site energies of hydrogen in these alloys are obtained by fitting to the data. It is found that the site energy at a Pd6-iMi octahedral site (M identical to Ag, Cu; i=0, . . ., 6) is not a linear function of the index i. It is suggested that this non-linear behaviour originates from a local electronic effect related to the filling of the Pd d band by Ag or Cu electrons.