Cu and Zn Substituted Silicon Clathrates with the Cubic Type-II Structure: Synthesis and Characterization of Cs8Na16Cu3.8Si132.2 and Cs8Na16Zn6.9Si129.1

Zeitschrift für Anorganische und Allgemeine Chemie

4 years ago

Cu and Zn Substituted Silicon Clathrates with the Cubic Type-II Structure: Synthesis and Characterization of Cs8Na16Cu3.8Si132.2 and Cs8Na16Zn6.9Si129.1

Marion C. Schäfer, Svilen Bobev

Studies in the systems Cs–Na–Cu–Si and Cs–Na–Zn–Si yielded the novel clathrates Cs8Na16(Cu,Si)136 and Cs8Na16(Zn,Si)136, both with the cubic type-II structure [space group Fd3m (no. 227), Pearson symbol cF160]. 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 96g, exclusively. In the structure of Cs8Na16(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 96g over site 32e. The corresponding refined compositions and unit cell parameters are as follows: Cs8Na16Cu3.8Si132.2(1) [a = 14.7583(15) Å]; Cs8Na16Zn6.9Si129.1(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.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/zaac.201700236