THERMODYNAMIC ASPECTS OF HYDROGEN MOTIONS IN DILUTE METALLIC SOLUTIONS

Mainly using available precise thermodynamic data for dilute solutions of hydrogen and deuterium in palladium and in the Pd0.9Ag0.1 alloy, we show that the description of the hydrogen atoms as simple harmonic oscillators represents a very crude first approximation only. Similarly, the other simple models which have been advanced are not consistent with all the available thermodynamic data. We propose to consider hydrogen dissolved in metals at high temperature as a very dense liquid rather than as a gas (as is usually done). We have also been led to conclude that the force constant for hydrogen in fcc metals should be slightly larger than for deuterium. © 1979.