Rare-earth cobalt aluminides with Y₂Co₃Ga₉-type structure

Chem. Met. Alloys 4 (2011) 243-250

https://doi.org/10.30970/cma4.0201

Yuriy LUTSYSHYN, Yaroslav TOKAYCHUK, Roman GLADYSHEVSKII

Two new rare-earth cobalt aluminides, Gd₂Co₃Al₉ and Tb₂Co₃Al₉, were synthesized. Their crystal structures and the structure of Sm₂Co₃Al₉ were refined from X-ray powder diffraction data: Y₂Co₃Ga₉ structure type, oS56, Cmcm, a = 12.8263(7), b = 7.5192(4), c = 9.4054(6) Å for the Sm-containing compound, a = 12.7883(8), b = 7.4955(5), c = 9.3711(6) Å for the Gd-containing compound, and a = 12.7606(9), b = 7.4783(5), c = 9.3332(6) Å for the Tb-containing compound. The structures are built from monoatomic R₄Al₆ layers (triangle mesh of R atoms and Al₃ triangles in ratio 2:1) and puckered Co₆Al₁₂ layers (triangle mesh of Co and Al atoms in the ratio 1:2) alternating along [001].

Perspective view of the structure of R₂Co₃Al₉ (Y₂Co₃Ga₉ type)

Keywords

Aluminide / Rare-earth metal / Cobalt / X-ray powder diffraction / Crystal structure