Solute concentrations and stresses in nanograined H–Pd solid solution Original Research Article

In the present work, we applied the Gibbs-approach-based adsorption isotherm for nanograined polycrystals to H–Pd solid solutions. Using the published experimental data of lattice strain and sample strain of the nanograined Pd, with an average grain size of 10 nm and in thermodynamic equilibrium with an H2 partial pressure, we determined H concentrations and stresses, as a function of the H2 partial pressure, in both grains and grain boundaries. More importantly, we determined the intrinsic properties of grain boundaries, such as the grain boundary bulk modulus, the grain boundary excess thickness, and the difference in chemical potential between grains and grain boundaries. With the determined intrinsic properties, the Gibbs-approach-based adsorption isotherm predicted the segregation of H in grain boundaries of nanograined Pd with an average grain size of 5 nm. The predication was verified by other reported experimental data.