Crystal structure and magnetic properties of the Y2Co17−xGax phases

In order to clarify the influence of the substitution of Co by Ga in Y2Co17−xGax with x = 0, 0.9, 1.9, 3.23, 4.75, 5.7 and 8.55 on the basic magnetism, X-ray diffraction and magnetic studies were carried out. The structure refinement for the Y2Co16.1Ga0.9 alloy has shown that the Ga atoms form a statistical mixture with the Co atoms only in the Wyckoff 12(k) position (layers with Kagome nets). The partial disorder of the Y atoms and the Co-Co pairs, located along the [0 0 1] direction in the hexagonal channels formed by Kagome nets, was also observed. Both the Co saturation magnetic moment, μCo, and Curie temperature, TC of Y2Co17−xGax decreased from 1.39 to 0.27μB and from 1167 to 67 K for x = 0 and 8.5, respectively. Furthermore, the substitution of the Co by Ga in Y2Co17−xGax with x = 4.75 and 8.55 is accompanied by loses of their ferromagnetism and the alloys become paramagnetic at room temperature.