Deuterium site occupation and magnetism in Ho6Fe23Dsub(x) compounds

High resolution neutron diffraction techniques were used to establish the hydrogen (deuterium) site occupation and sublattice magnetization of a series of Ho6Fe23Dsub(x) compounds (x = 1.5, 8.2, 12.1 and 15.7). The f.c.c. structure of the parent compound was maintained except for the Dsub(12.1) sample which exhibited a tetragonal distortion. The f.c.c. lattice was re-established for the higher Dsub(15.7) composition. Diffraction and inelastic hydrogen vibration spectra data demonstrate conclusively that the deuterium atoms in the Dsub(1.5) material fully occupy the octahedral a site with the residual in the tetrahedral f site. At the Dsub(8.2) and higher concentration level, the a site is empty and the deuterium atoms partially occupy only the tetrahedral sites. The 4 K holmium magnetic moment was near the free-ion value of 10 μsub(B) for all compounds and was oriented antiparallel to all four iron site moments (b, d, f1 and f2). For the cubic materials, the magnetization on the iron sites varied with deuteration in the range 0.8-2.4 μsub(B), with the Dsub(15.7) compound showing the highest iron moment for all sites. A spin reorientation is observed in the tetragonal material between room temperature and 4 K with the holmium and iron b and n1 moments rotating out of the basal plane. (Auth.)