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The 2 a 0 × 2 a 0 × 2 a 0 Superstructure in the Clathrate‐I K 8 Li x Ge 44– x /4 □ 2–3 x /4
Author(s) -
Liang Ying,
CarrilloCabrera Wilder,
Ormeci Alim,
Böhme Bodo,
Baitinger Michael,
Grin Yuri
Publication year - 2015
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/zaac.201400565
Subject(s) - crystallography , superstructure , crystal structure , thermal decomposition , x ray crystallography , clathrate hydrate , annealing (glass) , diffraction , bar (unit) , chemistry , lithium (medication) , materials science , hydrate , physics , thermodynamics , medicine , organic chemistry , meteorology , optics , composite material , endocrinology
Abstract. In the crystal structure of the clathrate‐I K 8 Li x Ge 44– x /4 □ 2–3 x /4 , the K atoms fill the polyhedral cages of a host framework formed by Li and Ge atoms. The phase has been obtained in two forms, at elevated temperatures with space group Pm $\bar{3}$ n , and at low temperatures with a 2 a 0 × 2 a 0 × 2 a 0 superstructure. In this work, we report on the direct preparation of the low‐temperature form by thermal decomposition of the precursor phase K 7 LiGe 8 at 400 °C. The obtained product K 8 Li 2.48(7) Ge 43.37(9) □ 0.15(6) [ a = 21.5489(2) Å, Z = 8] was found to be virtually identical with the one prepared by annealing of the high‐temperature form at this temperature. The superstructure was investigated by X‐ray powder diffraction and transmission electron microscopy, revealing the space group Ia $\bar{3}$ d . The low‐temperature form of K 8 Li x Ge 44– x /4 □ 2–3 x /4 represents one of the rare examples for a clathrate‐I superstructure primarily caused by an ordered arrangement of heteroatoms. Two similar, yet inequivalent models for the description of the ordering of lithium atoms in the framework are discussed.