THE INFLUENCE OF BORON ON THE MAGNETIC-PROPERTIES OF 2-17 AND 2-14 RARE-EARTH COBALT COMPOUNDS

The influence of B atom on the magnetic properties of R(2)Co(17-x)B(x) (R=Y; Nd and Sm) with 0 less than or equal to x less than or equal to 1 and Y2Co14Bx With 0.75 less than or equal to x less than or equal t o 1 was studied by means of NMR and magnetic measurements. The Co-59 N MR results for R(2)Co(17-x)B(x). show that the shorter the distance be tween Co and the nearest-neighbor (n.n.) B, the larger the decrease in the Co moment. The Co-59 hyperfine fields at the 18f site in Sm2Co17- xBx decrease greatly and the Co orbital moments, mu(orb), increase. Th us there is a possibility that the axial anisotropy strengthens. The B -11 NMR results for R(2)Co(17-x)B(x) show that there are Co atoms with increased moments. The Co moment decreases in R(2)Co(17-x)B(x) with 0 less than or equal to x less than or equal to 1, while increases in Y 2Co14Bx with 0.75 less than or equal to x less than or equal to 1. Thi s is explained in terms of the different distances between Co and B du e to the different crystal structures. Therefore the moment of the fir st n.n. Co atom of B decreases and that of the second n.n. Co atom of B increases.