Pressure-composition isotherms for nanocrystalline palladium hydride

Abstract
We present results from Monte Carlo simulations of the pressure-composition isotherms of nanometer-size palladium clusters under hydrogen loading. In contrast to simulations of bulk samples, the clusters do not show a phase transformation upon hydriding. A study of the hydrogen loading of the clusters shows that they load the surface first and then the interior, with no evidence of a phase transformation. We relate this behavior of our models to the observed narrowing of the plateau (miscibility gap) in the phase boundary of the pressure-composition phase diagram of nanocrystalline palladium.