Processing and applications of rare earth metals and intermetallic compounds

Surface modification of R-Fe-N intermetallic compounds was made to improve their magnetic property and nitrogen-absorbing ability, and high-performance resin-bonded magnets and nitrogen storage materials were developed: Surface coating for Sm2Fe17Nx by the zinc metal produced via photodecomposition of Zn(C2H5)(2) was effective to avoid the further oxidation in the molding process of the fine powders for bonded magnets and the resulting (BH)(max) values were improved to similar to 186 kJm(-3). Meanwhile, R2Fe17 as the mother compounds for R2Fe17Nx was highly active for decomposition of NH3 molecule and subsequent nitrogen absorption as metal nitrides. Furthermore, even inert N-2 molecule was dissociated on them by impregnating Ru metal and the resulting nitrogen atoms were absorbed in the crystal lattice of R2Fe17. These results demonstrated that the nitrogen storage system was established by cycling the nitrogenation and hydrogenation of R2Fe17/R2Fe17Nx materials.