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Quaternary Germanides Formed in Molten Aluminum: Tb 2 NiAl 4 Ge 2 and Ce 2 NiAl 6‐x Ge 4‐y (x ∼ 0.24, y ∼ 1.34)
Author(s) -
Sieve Brad,
Trikalitis Pantelis N.,
Kanatzidis Mercouri G.
Publication year - 2002
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/1521-3749(200207)628:7<1568::aid-zaac1568>3.0.co;2-a
Subject(s) - germanide , crystallography , intermetallic , tetragonal crystal system , chemistry , antiferromagnetism , neutron diffraction , crystal structure , superstructure , valency , paramagnetism , condensed matter physics , physics , thermodynamics , linguistics , germanium , philosophy , organic chemistry , alloy , silicon
Abstract The intermetallic phases Tb 2 NiAl 4 Ge 2 and Ce 2 NiAl 6‐x Ge 4‐y (x ∼ 0.24, y ∼ 1.34) were synthesized in molten Al at temperatures below 1000 °C. Both compounds adopt the tetragonal space group I4/mmm with cell parameters of a = 4.1346(2) Å c = 19.3437(7) Å for Tb 2 NiAl 4 Ge 2 and a = 4.1951(9) Å and c = 26.524(7) Å for Ce 2 NiAl 6‐x Ge 4‐y . The Tb 2 NiAl 4 Ge 2 structure features NiAl 4 Ge 2 layers separated by a double layer of rare earth ions. The Ce 2 NiAl 6‐x Ge 4‐y (x ∼ 0.24, y ∼ 1.34) structure also contains the NiAl 4 Ge 2 layers along with a vacancy defect PbO‐type Al 2‐x Ge 2‐y layer, and is related to the Ce 2 NiGa 10 structure type. Ordering of vacancies cause the formation of a 3ax3b superstructure in the crystal as seen by electron diffraction experiments. Tb 2 NiAl 4 Ge 2 exhibits Curie‐Weiss paramagnetic behavior with an antiferromagnetic transition observed at ∼20 K. Ce 2 NiAl 6‐x Ge 4‐y shows a much more complex magnetic behavior possibly due to temperature induced variation in the valency of the Ce atoms.