The low-temperature behaviour of annealed, quenched or irradiated solid solutions of hydrogen in erbium

Solid solutions alpha -Er(H,D)x, with 0<or=x<or=0.03, have been investigated by measuring the resistivity evolution between 4.2K and room temperature. Similarly to the earlier studied phases alpha -LuHx and alpha -Tm(H,D)x, a resistivity anomaly is observed at 160-180K, which is a function of isotope mass and concentration. Hydrogen defects were introduced by electron irradiation at 15K and/or by quenching from room temperature. These defects interact strongly with the magnetic structure of erbium and anneal out in the region of the anomaly. The phenomena are interpreted in the framework of the pair model, assuming a stable H-H (D-D) configuration below the anomaly region, the defects being isolated H-atoms which result from the pair dissociation through electron bombardment or are quenched in from the high-temperature alpha -phase.