Quaternary phases with Fe2P-type
structure in R-Ag-Al-Ge systems (R =
Pr, Sm)
Chem.
Met. Alloys 3 (2010) 53-61
https://doi.org/10.30970/cma3.0173
Roksolana KOZAK, Oksana ZAHARKO, Antonio CERVELLINO, Lev AKSELRUD, Roman GLADYSHEVSKII
The existence of limited solid solutions based on the ternary compounds PrAg1.40‑1.20Ge0.60‑0.80 and SmAg1.40‑0.98Ge0.60‑1.02
with Fe2P-type structure (hP9, P-62m),
was established at 33.3 at.% R in the
quaternary systems R–Ag–Al–Ge (R = Pr, Sm)
at 873 K. The crystal structures of the solid solutions were determined
from conventional X-ray (a = 0.7232(1),
c = 0.44081(8) nm for the
composition PrAg0.90Al0.35Ge0.75 and a
= 0.71180(5), c = 0.43634(5) nm for SmAg0.90Al0.39Ge0.71)
and synchrotron (a = 0.72311(2), c = 0.44101(2) nm
for PrAg0.87Al0.38Ge0.75) powder
diffraction data. A statistical mixture of Ag and Al atoms
occupy the 3g site and forms columns
of trigonal prisms with Ge
atoms at the center (1a site), whereas a statistical
mixture of Ge and Ag atoms is situated at the centers
of the trigonal prisms R6 (2d site).
Atomic coordinates and isotropic
displacement parameters for PrAg0.87Al0.38Ge0.75 (Fe2P, hP9, P-62m, a = 0.72311(2),
c = 0.44101(2) nm, Z = 3).
Keywords
Rare-earth / Silver / Aluminum / Germanium /
Solid solution / X-ray diffraction / Crystal structure