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