Crystal chemical peculiarities
of rare earth (R) rich magnesium intermetallic compounds in R–T–Mg (T =
transition element) systems
Chem.
Met. Alloys 2
(2009) 39-48
https://doi.org/10.30970/cma2.0088
Pavlo SOLOKHA, Serena DE NEGRI, Volodymyr PAVLYUK,
Adriana SACCONE
The rare earth rich compounds R23Ni7Mg4
(R = Ce, Pr) and R4NiMg (R = La, Tb, Dy, Ho, Er)
were synthesized by slow thermal treatment in a resistance furnace, starting
from element pieces enclosed in sealed Ta crucibles. SEM-EDXS analyses were
performed for monitoring the phase composition. The crystal structures of the
majority of these intermetallics were investigated by X-ray diffraction on
single crystals. The R23Ni7Mg4 compounds
crystallize in the Pr23Ir7Mg4 structure type: P63mc, hP68,
Z = 2, for Ce a = 0.99742(1),
c = 2.25206(4) nm, wR2 = 0.0686,
1483 F2 values, 74
variables; for Pr a = 0.99249(4),
c = 2.24460(9) nm, wR2 = 0.0735,
1395 F2 values, 74
variables; for La a = 1.01234(8),
c = 2.2887(2) nm, RB = 7.3%
and RF = 5.1%. The series of isostructural R4NiMg
compounds belongs to the Gd4RhIn structure type, F4¯3m, cF96,
Z = 16.
Unit cell projections of the Ce23Ni7Mg4
structure. The
coordination polyhedra of the atoms are shown; symmetries of the central atoms
are indicated in parentheses.
Keywords