New Type-I and Type-II Clathrates in the Systems Cs–Na–Ga–Si, Rb–Na–Ga–Si, and Rb–Na–Zn–Si

Inorganics

Marion C. Schr¹ 

[1] Department of Chemistry & Biochemistry, University of Delaware, Newark, DE 19716, USA; E-Mail

关键词: clathrates;    type-I structure;    type-II structure;    silicon;   

DOI  :  10.3390/inorganics2010079

来源: mdpi

【 摘 要 】

Systematic studies in the systems Cs–Na–Ga–Si, Rb–Na–Ga–Si, and Rb–Na–Zn–Si yielded the novel type-I clathrates with refined compositions Cs₆Na₂Ga_8.25Si_37.75(3), Rb_6.34Na_1.66(2)Ga_8.02Si_37.98(3), and Rb_5.20Na_2.80(4)Zn_3.85Si_42.15(2) (cubic, Pm3n), as well as the type-II clathrates with formulae Cs₈Na₁₆Ga_22.7Si_113.3(1), Rb_8.4Na_15.6(1)Ga_19.6Si_116.4(1), and Rb₈Na₁₆Zn_8.4Si_127.6(1) (cubic, Fd3m). In each system, the type-I and -II compounds are always co-crystallizing, irrespective of the reaction conditions. The structures derived from single-crystal X-ray diffraction confirm complete ordering of Cs and Na atoms, and nearly complete ordering of the Rb and Na guest atoms. The framework-building Si atoms are randomly substituted by Ga or Zn atoms on all framework sites with notable difference in the substitution patterns between the type-I and type-II structure. This, and other details of the crystal chemistry are discussed in this paper.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.