CRYSTALLOGRAPHIC AND MAGNETIC-PROPERTIES OF R2FE17CX WITH R=Y, PR, ND, SM, GD, DY, AND ER

A series of R2Fe17C(x) compounds (R = Y, Pr, Nd, Sm, Gd, Dy, and Er; x = 0, 0.5 and 1.0) were synthesized. X-ray diffraction analyses showed that the crystal structure is rhombohedral Th2Zn17 type for R = Pr, Nd, Sm, and Gd. For R = Y, Dy and Er, a structure transformation from hexagonal Th2Ni17 type (x = 0.5) to rhombohedral Th2Zn17 type (x = 1.0) was observed. The introduction of C into R2Fe17 leads to an expansion of the lattice. It strongly enhances Curie temperature. C atoms occupy interstitially the nearest neighbour sites to the R atoms in the lattice. The anisotropy of R sublattice was strengthened. A uniaxial anisotropy was observed in Sm2Fe17C0.5 at room temperature.