Structural and magnetic properties of DyCo5−xGax compounds

The structural and magnetic properties of DyCo5−xGax compounds with x = 0.55, 0.85, 1.15, 1.45 and 1.75, have been investigated by X-ray diffraction and magnetic measurements. Powder X-ray diffraction analysis revealed that the DyCo5−xGax samples are stabilized in single phase with a hexagonal CaCu5-type structure (space group P6/mmm) for 0.55 ≤ x ≤ 1.45. The substitution of Co by Ga in this compound increases its lattice parameters a, c and cell volume V but decreases the 3d-sublattice moment and the 3d uniaxial anisotropy. As result, the compensation temperature Tcomp increases from 199 K (for the sample with x = 0.55) to 260 K (for the sample with x = 1.45). Two spin reorientation transitions, at TSR1 = 460 and TSR2 = 725 K, respectively, for the sample with x = 0.55, only one at TSR3 = 466 K for the sample with x = 0.85 while none for the samples with x = 1.15 or less were found. The Curie temperature decreases with increasing Ga content. The total magnetization for the compound increases at low temperature (e.g. 100 K) but decreases at high temperature with increasing Ga content (e.g. 300 K).