Effects of Ga substitution on the hard magnetic properties of the Sm 2Fe 17C 1.5 compounds

Abstract

A systematic investigation of the structure and magnetic properties of arc-melted and as-quenched Sm 2Fe 17− x Ga x C 1.5 samples with 0 ≤ × ≤ 6 has been made by X-ray diffraction and magnetic measurements, X-ray diffraction studies have shown that these samples crystallize in the rhombohedral Th 2Zn 17-type structure. The unit-cell volumes υ of Sm 2Fe 17− x Ga x C 1.5 compounds increase monotonically with increasing Ga concentration. The Ga-concentration dependence of the Curie temperature T C exhibits a maximum value of 633 K at about x = 2. The room-temperature saturation magnetization M s decreases monotonically with increasing Ga concentration. The Sm 2Fe 17− x Ga x C 1.5 compounds exhibit an easy c-axis anisotropy at room temperature. The anisotropy field is found first to increase and then to decrease with increasing x, having a maximum value of 130 kOe at about x = 2. The coercivities of 13.0–16.0 kOe are obtained in as-quenched Sm 2Fe 17- x Ga x C 1.5 ( x = 2 and 3) ribbons prepared at the speeds of 15–30 m/s at room temperature. The substitution of Ga in Sm 2Fe 17C 1.5 not only stabilizes the hard magnetic phase but also leads to the increase in coercivity.