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Cu and Zn Substituted Silicon Clathrates with the Cubic Type‐II Structure: Synthesis and Characterization of Cs 8 Na 16 Cu 3.8 Si 132.2 and Cs 8 Na 16 Zn 6.9 Si 129.1
Author(s) -
Schäfer Marion C.,
Bobev Svilen
Publication year - 2017
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.201700236
Subject(s) - crystallography , crystal structure , ternary operation , chemistry , octahedron , silicon , type (biology) , x ray crystallography , clathrate hydrate , zinc , diffraction , hydrate , physics , optics , programming language , organic chemistry , computer science , ecology , biology
Studies in the systems Cs–Na–Cu–Si and Cs–Na–Zn–Si yielded the novel clathrates Cs 8 Na 16 (Cu,Si) 136 and Cs 8 Na 16 (Zn,Si) 136 , both with the cubic type‐II structure [space group Fd 3 m (no. 227), Pearson symbol cF 160]. The structures of the title compounds were established from single‐crystal X‐ray diffraction methods, confirming the complete ordering of the Cs and Na guest atoms. The framework‐building Si atoms are found to be randomly substituted by Cu atoms on framework site 96 g , exclusively. In the structure of Cs 8 Na 16 (Zn,Si) 136 , the refinements indicate that the Zn and Si atoms co‐occupy two of the three framework sites with notable preference for site 96 g over site 32 e . The corresponding refined compositions and unit cell parameters are as follows: Cs 8 Na 16 Cu 3.8 Si 132.2(1) [ a = 14.7583(15) Å]; Cs 8 Na 16 Zn 6.9 Si 129.1(1) [ a = 14.7682(5) Å], respectively. The type‐II clathrates can be obtained only from experiments employing both Na and Cs, whereas work in the ternary Cs‐Cu‐Si, Cs‐Zn‐Si, Na‐Cu‐Si, and Na‐Zn‐Si systems failed to yield any clathrate phases. At the same conditions, exploratory studies in the K‐Zn‐Si and Rb‐Zn‐Si systems provided evidence that type‐I clathrates are favored.