STUDY OF THE HYDROGEN SOLID-SOLUTION IN THULIUM

Solid solutions of hydrogen in thulium are investigated, mainly by X-ray determinations in the temperature range 20-500°C. Several observations lead us to distinguish between two variaties α and α*. In the range of existence of the α* phase, below the transition temperature of 120°C, the hydrogen interstitials induce in the metal lattice a behaviour different from that of the α phase, as concerns the phase equilibrium, the additional resistivity, and the lattice anisotropy. Several simple models are proposed for the explanation of this anomaly, encountered also in other heavy rate earth-hydrogen systems. © 1979.