Changes of the magnetic properties upon hydrogen absorption in rare-earth iron compounds

The absorption of hydrogen in rare-earth iron compounds of the type RFe2 was studied. X-ray diffraction showed that the cubic C15 structure is retained but that the unit cell volume is strongly increased (up to 30%). With the exception of CeFe2 hydrogen absorption gives rise to a drastic lowering of the Curie temperature. The moment of the Fe atoms increases upon hydrogen absorption. In the hydrides, too, the coupling between the iron moments and the rare-earth spin is antiparallel. (Auth.)