RNIAL HYDRIDES AND THEIR MAGNETIC-PROPERTIES

RNiAl compounds absorb hydrogen at normal pressure typical to a stoich iometry of RNiAlHapproximate to 1.4. Thermal desorption studies showed that, besides such hydrides, several partly decomposed hydrides with lower H concentrations are also stable. The X-ray analysis shows that, in most cases, hydrogenation leads to an orthorhombic distortion of t he original hexagonal structure of the ZrNiAl type. The hydrogenation severely affects magnetic properties depressing ordering temperatures and changing all the magnetic phase diagrams. (C) 1997 Elsevier Scienc e S.A.