Journal Archive

The high diffusibility of hydrogen in solid phases of the palladium-hydrogen system allows thermodynamic equilibrium to be established over a wide range of experimental conditions. Evidence has long existed that, in the hydride phases formed, the hydrogen:palladium ratio is not simple and is a function of equilibrium pressure and of temperature. Theoretical models of the system have often centred on modifications of the palladium electron band structure due to hydrogen absorption but increasing attention has been paid to the consequences of lattice strain. The position is now reviewed in the light of recent work.