Defect kinetics in quenched and electron-irradiated α-ScH(D)x solid solutions

The resistivity anomaly observed at 150 to 160 K in ScH(D) solidsolutions is investigated in detail, after determination of the low-temperature hydrogen solubility limit to xmax = (0.35 ± ± 0.02) at. H(D)/at. Sc. Quench and/or electron irradiation are used to introduce hydrogen defects increasing the residual resistivity. The electron-energy dependence of the damage production rate is fitted with electron-hydrogen interaction cross sections reproducing the decreasing Δϱirr(E) dependence withincreasing E. The annealing behaviour of the quenched-in damage exhibits a recovery stage in the anomaly region; its kinetic analysis permits to establish a first-order reaction and to determine the defect migration energies, E(H) = (270 ± 15) meV and E(D) = (300 ± 10) meV. The irradiation-damage annealing shows the same recovery stage, but appears disturbed by the annealing of defects in the Sc-host lattice. The H defects are discussed in the framework of the HH pair condensation model established earlier for the system LuH. The binding energies of the condensated structures are determined to Eb(H) = (50 ± 2) meV and Eb(D) = (57 ± 2) meV. A comparison with other α-phase systems shows correlations between Eband the c/a-ratio of the host lattice as well as between E and its atomic volume. Nous avons etudie l'anomalie de resistivite observee a 150 a 160 K dans des solutions solides ScH(D), ayant determine la limite de solubilite de l'hydrogene a basse temperature: xmax = (0,35 ± 0,02) at. H(D)/at. Sc. La trempe et l'irradiation electronique introduisent des defauts hydrogene en augmentant la resistivite residuelle. Nous avons calcule des sections efficaces d'interaction electron-hydrogene en reproduisant la diminution du dommage introduit avec l'energie, Δϱirr(E). Le recuit des defauts de trempe montre un stade de guerison dans la region de l'anomalie; son analyse cinetique permet d'etablir une reaction de premier ordre et de determiner les energies de migration des defauts: E(H) = (270 ± 15) meV et E(D) = (300 ± 10) meV. Le recuit des defauts d'irradiation montre le měme stade de guerison, mais paraǐt perturbe par le recuit de defauts intrinseques du reseau Sc. On discute les defauts H dans le cadre du modele de condensation en paires HH etabli auparavant pour le systeme LuH. Les energies de liaison des structures condensees trouvees sont: Eb(H) = (50 ± 2) meV et Eb(D) = (57 ± 2) meV. Comparaison avec d'autressystemes en phase α montre des correlations entre Eb et le rapport c/a du reseau hǒte ainsi qu'entre E et les volumes atomiques.