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

Abstract

The crystal structure and magnetic properties of Nd 2− x Tb x Fe 17 and NdTbFe 17− y Al y compounds were studied by means of X-ray diffraction and magnetization measurements. All the samples show the rhombohedral Th 2Zn 17-type structure with space group R 3 ¯ m . For Nd 2− x Tb x Fe 17 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 10.54 μ B/f.u. per Tb atom. For NdTbFe 17− y Al y 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.