New compounds RNiAl₃ (R = Gd, Tb, Dy)

Chem. Met. Alloys 3 (2010) 35-41

https://doi.org/10.30970/cma3.0174

Svitlana PUKAS, Oksana MATSELKO, Roman GLADYSHEVSKII

Three new and two already known rare-earth nickel aluminides RNiAl₃ (R = Y, Sm, Gd, Tb, and Dy) were synthesized by arc melting and their crystal structures were studied by X-ray powder diffraction. They are isotypic to YNiAl₃: Pearson symbol oP20, space group Pnma, a = 8.1532(5), b = 4.0426(2), c = 10.6349(7) Å for YNiAl₃, a = 8.1871(1), b = 4.09150(7), c = 10.7013(2) Å for SmNiAl₃, a = 8.164(2), b = 4.0680(9), c = 10.666(3) Å for GdNiAl₃, a = 8.1484(2), b = 4.05440(8), c = 10.6328(3) Å for TbNiAl₃, and a = 8.133(1), b = 4.0350(7), c = 10.611(2) Å for DyNiAl₃. A complete structure determination was carried out for SmNiAl₃. The structure type YNiAl₃ is built up of tricapped trigonal prisms centered by Ni atoms. It is compared with closely related structure types with the ratio R:Ni = 1:1, in particular MgCuAl₂ and YNiAl₄, which also have many representatives in R–Ni–Al systems.

Ni-centered tricapped trigonal prisms Sm₂Al₇ in the structure of the compound SmNiAl₃.

Keywords

Rare-earth nickel aluminide / X-ray powder diffraction / Crystal structure