Crystallographic and magnetic studies on iron-rich mixed rare-earth intermetallics (Nd/Tb)2(Fe/Al)17

The crystal structure and magnetic properties of Nd2−xTbxFe17 and NdTbFe17−yAly compounds were studied by means of X-ray diffraction and magnetization measurements. All the samples show the rhombohedral Th2Zn17-type structure with space group R3¯m. For Nd2−xTbxFe17 compounds, the lattice parameters decrease with increasing Tb concentration, and the Curie temperature increases with the Tb content while the saturation magnetization decreases linearly at a rate of 10.54μB/f.u. per Tb atom. For NdTbFe17−yAly compounds, the substitution of Al for Fe leads to an increase in lattice parameters a, c and unit-cell volume V. The Al atoms preferentially occupy 18 h site at low Al concentration whereas prefer to occupy 6c and 18f sites at high Al concentration. The Curie temperature increases with Al content up to y = 3 then decreases for 3 ≤ y ≤ 8. X-ray diffraction of magnetically pre-aligned samples indicates that the easy magnetization direction of the samples changes from planar to c-axial with increasing aluminum concentration. The saturation magnetization of compounds decreases with increasing Al concentration.