EFFECT OF HYDROGEN ON THE MAGNETIC-PROPERTIES OF Y2FE14B

The effects of hydrogen on the intrinsic magnetic properties (saturation magnetization, anisotropy, Moessbauer spectra) of Y//2Fe//1//4BH//x are studied for 0 less than equivalent to x 23 3. 37. The increase in Curie temperature, dT//c/dx approximately equals 30 K for x less than 1, is related to a slight increase in iron moment on hydrogenation. There is a sharp fall in the anisotropy constant K//1 which is partly offset at 4. 2 K by a rise in K//2. An important part of the anisotropy arises from iron sites belonging to the (Y,Fe)//4 tetrahedra which are occupied by hydrogen.