Crystallographic properties of ErFe6Sn6−xGax compounds (0 < x < 6)

The compounds ErFe6Sn6−xGax (0 ≤ x ≤ 6) have been studied by powder X-ray diffraction. It is observed that the replacement of the tin atoms by gallium atoms leads to a stabilisation of the HfFe6Ge6-type ErFe6Sn6−xGax (0.25 ≤ x ≤ 2.5) compounds and ScFe6Ga6-type ErFe6Sn6−xGax (4.0 ≤ x ≤ 5.5) compounds. The refinement of the crystal structure of ErFe6Sn4Ga2 indicates that the gallium atoms mainly occupy the Fe6Er3 tri-capped trigonal prism. These results suggest that the stabilisation of the HfFe6Ge6 structure is driven by the relaxation of the Er-(Sn,Ga) contacts within the tri-capped trigonal prism.