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M 2 Ga 6 Te 10 (M: Li, Na): Two New Non‐metallic Filled β‐Manganese Phases – X‐ray and NMR Studies
Author(s) -
Deiseroth H. J.,
Kienle L.,
Günther H.,
Hartung M.
Publication year - 2000
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/(sici)1521-3749(200001)626:1<302::aid-zaac302>3.0.co;2-3
Subject(s) - crystallography , chemistry , octahedron , manganese , crystal structure , metal , ion , homogeneous , nmr spectra database , lattice constant , metal ions in aqueous solution , single crystal , spectral line , physics , diffraction , optics , organic chemistry , astronomy , thermodynamics
Two new non‐metallic filled β‐manganese phases M 2 Ga 6 Te 10 (M: Li, Na) are obtained as black, homogeneous, microcristalline samples as well as single crystals by direct reaction of the elements. According to the single crystal structure determinations both compounds crystallize in space group R32 (No. 155, Z = 2) with the lattice constants: a = 1436.9(2), c = 1759.0(4) pm (T = 180 K, Li 2 Ga 6 Te 10 ) and a = 1458(1) pm, c = 1776.1(4) pm (T = 290 K, Na 2 Ga 6 Te 10 ). Their structures are characterized by tetrahedral close packings of Te 2– , corresponding to the arrangement of Mn atoms in β‐Mn. While Ga 3+ ions are distributed in an ordered way over 12% of the tetrahedral holes, the M + ions occupy all distorted octahedral (“metaprismatic”) holes. As the Li + ions are too small they occupy off‐center positions inside the metaprisms. Positions with the strongest off‐centering can only be refined on the basis of a split model. MAS‐NMR measurements, including multiple quantum NMR, allowed the two different crystallographic M + sites to be distinguished unambigously by separate 7 Li and 23 Na signals, respectively. The assignment of the NMR signals was supported by measurements of samples in which Li + was partly substituted by larger cations (Sn 2+ , Pb 2+ ).