HYSTERESIS OF PRESSURE - COMPOSITION AND ELECTRICAL-RESISTANCE - COMPOSITION RELATIONSHIPS OF PALLADIUM-HYDROGEN AND PALLADIUM ALLOY-HYDROGEN SYSTEMS

Over regions of α⇌ β-phase transformations in the palladium/hydrogen and palladium alloy/hydrogen systems, hysteretic differences between steady-state hydrogen pressure – hydrogen content relationships which occur during gradual increases and decreases of hydrogen content respectively – are paralleled by corresponding hysteretic differences of relationships between hydrogen content and other physical properties including electrical resistance. Electrical resistance - hydrogen content relationships obtained for the Pd/H system in the temperature range 10° – 85° in conjunction with hydrogen chemical potential – hydrogen content relationships are discussed with reference to information available at other temperatures. It is concluded that the hysteretic effects probably correspond partially to differences in overall dimensions arising from changes in the hydrogen contents and lattice constants of α and β-phase regions – both in the ‘plateau’ regions of the hysteresis loop, and also in the adjacent, less chemical potential invariant regions of the loop which seem to be associated with the onset of transitions. © by Akademische Verlagsgesellschaft