Effects of Ga substitution on the hard magnetic properties of the Sm2F17C1.5 compounds

A systematic investigation of the structure and magnetic properties of are-melted and as-quenched Sm2Fe17-xGaxC1.5 samples with 0 less than or equal to x less than or equal to 6 has been made by X-ray diffraction and magnetic measurements. X-ray diffraction studies have shown that these samples crystallize in the rhombohedral Th2Zn17-type structure. The unit-cell volumes upsilon of Sm2Fe17-xGaxC1.5 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 Sm2Fe17-xGaxC1.5 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 Sm2Fe17-xGaxC1.5 (x=2 and 3) ribbons prepared at the speeds of 15-30 m/s at room temperature. The substitution of Ga in Sm2Fe17C1.5 not only stabilizes the hard magnetic phase but also leads to the increase in coercivity.