The hydrogenation behaviour of the phases Sm₂Co₁₇ and Pr₂Co₁₇

Abstract

The compounds Sm₂Co₁₇ and Pr₂Co₁₇ have been charged with hydrogen and the hydrogen compositions determined between pressures of approximately 2.5×10⁻² and 13 atm at temperatures of 150 and 200° C. Very low rates of hydrogen absorption were observed below 150° C so that solubility measurements have not been obtained below this temperature. The X-ray diffraction studies show that the structure of the metal lattice is unchanged by the hydrogenation process, i.e. the rhombohedral, Th₂Zn₁₇ structure type with space groupR¯3_m is maintained. As a result of the expansion the alloys become cracked and friable on hydrogenation.