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The structural and magnetic properties of DyCo 5− x Ga x 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 DyCo 5− x Ga x samples are stabilized in single phase with a hexagonal CaCu 5 -type structure (space group P 6/ 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 T comp 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 T SR1 = 460 and T SR2 = 725 K, respectively, for the sample with x = 0.55, only one at T SR3 = 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).

The isothermal section of the Dy–Co–Ti system at 500 °C has been investigated in the whole composition range by means of X-ray diffraction, thermal analysis, scanning electron microscopy and energy dispersive X-ray spectroscopy. The only ternary phase DyTi x Co 12− x is of ThMn 12 -type structure, space group I 4/ mmm , and shows a small homogeneity range of 1 ≤ x ≤ 1.6. The lattice parameters for DyTi x Co 12− x with 1 ≤ x ≤ 1.56 are a = 0.8336(4)–0.8402(1) nm and c = 0.4691(3)–0.4727(1) nm. Along a constant Dy concentration, the solid solubilities of Ti in the compounds Dy 2 Co 17 , DyCo 3 , DyCo 2 and Dy 3 Co are about 2.0, 2.0, 3.0 and 4.0 at.%, respectively. The TiCo phase has a homogeneity range of 50–54 at.% Co at 500 °C and dissolves up to 2.0 at.% Dy.