Synthesis, structural characterization, and physical properties of the type-I clathrates A 8Zn 18As 28 (A = K, Rb, Cs) and Cs 8Cd 18As 28

Hua He, Alex Zevalkink, Zachary M. Gibbs, G. Jeffrey Snyder, Svilen Bobev*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

The first arsenide clathrates A 8Zn 18As 28 (A = K, Rb, Cs) and Cs 8Cd 18As 28 have been synthesized in high yields via a two-step route. These compounds adopt the type-I structure and exhibit structural characteristics different from the recently reported antimonide clathrates Cs 8Zn 18Sb 28 and Cs 8Cd 18Sb 28. In arsenide clathrates, Zn (or Cd) and As atoms are statistically mixed at the three framework sites: 6c, 16i, and 24k; the alkali metals reside inside the cages at the 2a and 6d sites, with the 2a site being only partially filled. Single-crystal X-ray diffraction studies confirm that the Cd atoms preferably occupy the 6c and 24k sites over the 16i site, with more than 80% of Cd found at the former two positions. A unique structural feature is a framework disorder coupled with the partial occupancy of the cage's 2a site. Optical absorption measurements and electronic property measurements reveal a semimetallic-like behavior for Cs 8Cd 18As 28 and semiconductor-like behavior for A 8Zn 18As 28 (A = Rb, Cs).

Original languageEnglish (US)
Pages (from-to)3596-3603
Number of pages8
JournalChemistry of Materials
Volume24
Issue number18
DOIs
StatePublished - Sep 25 2012

Keywords

  • arsenides
  • clathrates
  • crystal structure
  • thermoelectrics

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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