Magnetic Phase Relations of RCo3

RCo
₃
compounds with rhombohedral structure have been synthesized, and their structural and magnetic properties have been investigated using powder X-ray diffraction and magnetic measurements. Rietveld technology was used to determine the crystal structures of RCo
₃
. The lattice parameters and unit cell volumes decrease with increasing atomic numbers of R. Co-Co and R-Co bond lengths (BLs) were determined with Diamond Software according to the atomic positions. The rare earth dependence of magnetic phase diagram was studied systemically. Curie temperatures increase with increasing Co-Co and R-Co BLs in light rare earth regime and heavy rare earth regime. A modified magnetic valence model was used to investigate the magnetic moments of RCo
₃
. The magnetic moment depends only on the total number of d and s-p, as well as f electrons, and not on the bandshape. The valence numbers of rare earth also affect the moments.