Nature 443, 320-323 (21 September 2006) | doi:10.1038/nature05145; Received 23 March 2006; Accepted 8 August 2006

A guest-free germanium clathrate

Arnold M. Guloy1,2, Reiner Ramlau1, Zhongjia Tang1,2, Walter Schnelle1, Michael Baitinger1 and Yuri Grin1

The challenges associated with synthesizing expanded semiconductor frameworks with cage-like crystal structures continue to be of interest1, 2. Filled low-density germanium and silicon framework structures have distinct properties that address important issues in thermoelectric phonon glass–electron crystals3, superconductivity4 and the possibility of Kondo insulators5. Interest in empty framework structures of silicon and germanium is motivated by their predicted wide optical bandgaps of the same magnitude as quantum dots and porous silicon, making them and their alloys promising materials for silicon-based optoelectronic devices6, 7. Although almost-empty Na1-xSi136 has already been reported8, 9, the synthesis of guest-free germanium clathrate has so far been unsuccessful. Here we report the high-yield synthesis and characteristics of germanium with the empty clathrate-II structure through the oxidation of Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, or to obtain a text description, please contact npg@nature.com Zintl anions in ionic liquids under ambient conditions. The approach demonstrates the potential of ionic liquids as media for the reactions of polar intermetallic phases.

  1. Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
  2. Department of Chemistry and the Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5003, USA

Correspondence to: Arnold M. Guloy1,2Yuri Grin1 Correspondence and requests for materials should be addressed to Yu.G. (Email: grin@cpfs.mpg.de) and A.M.G. (Email: aguloy@uh.edu).


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