Influence of Hydrogen on the Magnetic Properties of the U-Co System

Hydrogen absorption can substantially change the structural and electronic properties of intermetallic compounds formed from 3d transition elements and the rare earths. Compounds of U--Co were made and tested for H absorption. It was found that cobalt-rich compounds do not absorb H, whereas U sub 6 Co and UCo readily react with the gas. Their reaction results in the formation of a hydride that has a different structure than the parent compound. U sub 6 Co changes to U sub 6 CoH sub 18 with a structure similar to that of beta -UH sub 3 and with similar magnetic properties. UCo becomes UCoH sub 2.7 , has a simple cubic structure, and has a transition to a magnetic order at 63K. These compounds also become superconducting. This is consistent with the rather low ultrasonic interatomic distances of these materials. 14 ref.--R.A.S.