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Complex Intermetallic Compounds: CaNi 5 Ge 3 , Ca 15 Ni 68 Ge 37 , and Ca 7 Ni 49 Ge 22 – Three Multifaceted Ni‐Ge Framework Structures Combining the Structural Motifs of Ni 3 Ge and CaNi 2 Ge 2
Author(s) -
Siggelkow Lisa,
Hlukhyy Viktor,
Wahl Bernhard,
Fässler Thomas F.
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201100347
Subject(s) - intermetallic , chemistry , crystallography , crystal structure , germanium , tantalum , space group , nickel , group (periodic table) , x ray crystallography , stereochemistry , diffraction , alloy , physics , organic chemistry , silicon , optics
The intermetallic compounds, CaNi 5 Ge 3 , Ca 15 Ni 68 Ge 37 , and Ca 7 Ni 48.9(4) Ge 22.1(4) , were prepared by arc‐melting of the elements and subsequent heating in welded tantalum ampoules. The compounds were investigated by powder and single‐crystal X‐ray diffraction methods. Each of the three compounds crystallized in a different structure type, namely, CaNi 5 Ge 3 in the space group P 4/ mbm , a = 8.0855(1) Å, c = 7.8466(1) Å, wR 2 = 0.054, 439 F 2 values, 31 variable parameters; Ca 15 Ni 68 Ge 37 in the space group P $\bar {6}$ 2 m , a = 22.436(2) Å, c = 3.9684(4) Å, wR 2 = 0.096, 1849 F 2 values, 133 variable parameters; Ca 7 Ni 48.9(4) Ge 22.1(4) in the space group P 6/ mmm , a = 17.381(4) Å, c = 4.046(1) Å, wR 2 = 0.082, 693 F 2 values, 59 variable parameters. The crystal structures consist of complex 3D networks of nickel and germanium atoms that have common motifs, namely, different sections of the Ni 3 Ge structure, as well as, Ca‐centered hexagonal prisms of Ni and Ge, which have been observed in the CaNi 2 Ge 2 structure. As the Ca content decreases, the Ni‐Ge substructures form one‐, two‐, and three‐dimensional networks. The disorder in Ca 7 Ni 48.9(4) Ge 22.1(4) is explained by a structural frustration. The electronic structure and chemical bonding of CaNi 5 Ge 3 is discussed by means of band‐structure calculations.