Structure and magnetic properties of Gd2Co17−xCrx (1.17 ≤ x ≤ 3.0) compounds

The structure and magnetic properties of Gd2Co17−xCrx (1.17 ≤ x ≤ 3.0) compounds have been investigated by means of X-ray diffraction (XRD) and magnetization measurements. The powder X-ray diffraction patterns show that all samples crystallize as a single phase with the rhombohedral Th2Zn17-type structure. The lattice parameters a and the unit cell volume V increases slightly with increasing Cr content, but the c parameter varies in a less simple way with increasing Cr content. The X-ray diffraction patterns of the magnetically aligned samples show that all compounds investigated have uniaxial anisotropy. Spin reorientation phenomena occur in all of the compounds. The Curie temperature TC, the spin reorientation temperature Tsr, the spontaneous magnetization M0 and the saturation magnetization Ms decrease with the increasing Cr content. The anisotropy constant K1 and the anisotropy field Ba of the compounds at room temperature reach a maximum for x = 1.76. The M0 and Ms increase with increasing temperature from 5 K to 300 K. The easy-axis anisotropy of all compounds changes to easy-plane anisotropy at low temperatures and the spin reorientation phenomena are more pronounced for low Cr concentration.