Magnetic properties of Sm2Co17-xGax (x=0-7) compounds

The study of the effect of Ga substitution on the magnetic properties of ar c-melted Sm2Co17-xGax (x=0-7) compounds has been carried out by means of x- ray diffraction (XRD) and magnetic measurements. XRD patterns show that all samples of Sm2Co17-xGax (x=0-7) crystallize in the rhombohedral Th2Zn17-ty pe structure. The Ga substitution for Co leads to an approximately linear d ecrease in the Curie temperature and a rapid decrease in the saturation mag netic moment which is faster than that in the case of magnetic dilution. Sp in-reorientation transition is observed for Sm2Co11Ga6 compound at 32 K. In order to determine the room-temperature easy magnetization direction (EMD) , XRD measurements are performed on magnetically aligned samples with x les s than or equal to 5. The result shows that the EMD of these compounds corr esponds to the c axis. The anisotropy constants K-1 and K-2 of Sm2Co17-xGax compounds were derived by fitting the hard-direction magnetization recoil curves measured on magnetically aligned powder samples as well as by fittin g the magnetization recoil curves measured on polycrystalline bulk samples. The fitting results indicate that the substitution of Ga for Co in Sm2Co17 compound decreases the anisotropy constants, thus indicating the weakening of the easy-axis anisotropy. (C) 2000 American Institute of Physics. [S002 1-8979(00)28308-4].