EFFECT OF HYDROGEN ABSORPTION ON THE MAGNETIC-PROPERTIES OF ND15FE77B8

Hydrogen-induced changes in the magnetic properties of the permanent magnetic material Nd//1//5Fe//7//7B//8 are reported. Increases in the magnetization and in the **5**7Fe hyperfine field were observed. In contrast, hydrogen absorption subtantially reduced the anisotropy contribution of the neodymium sublattice. As a consequence the spin reorientation temperature, although still present in the hydride was shifted to lower values. Unless the hydrogen was removed by a heat treatment only limited values for the energy product (BH)//m//a//x were obtained. From analysis of the Mossbauer spectra we presume that the occupation numbers at certain iron sites differ from those in the parent compound.