Solid solutions of H and D in yttrium metal

Resistivity differences between pure yttrium metal and a solid solution of H or D with yttrium in the atomic concentration range 0.05-0.24 alloy isotope effects and deviations from Matthiessen's rule to be investigated. A model of pair condensation is proposed to explain the transition encountered between 170 and 280K, to calculate the 'liquid-gas' transition energy (about 0.1 eV per atom unit) and also its concentration dependence. The added contribution to the resistivity in the 'gas' phase is attributed to short-range interstitial interactions.