JJAP Conference Proceedings

JJAP Conf. Proc. 3, 011201 (2015) doi:10.7567/JJAPCP.3.011201

Band structure characterization of KGaSi clathrates by optical measurement

Masaru Iioka1, Haruhiko Udono1, Motoharu Imai2, Masato Aoki3

  1. 1Graduate school of Science and Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511, Japan
  2. 2National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
  3. 3Faculty of Engineering, Gifu University, Gifu 501-1193, Japan
  • Received July 17, 2014
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Abstract

We have investigated the band structure of K8Ga8Si38 clathrates by using optical reflectance measurements and first-principle calculations based on the density functional theory. The imaginary part of the dielectric function ε2 was calculated from the normal reflectance spectrum via the Kramers–Kronig analysis. The experimental ε2 values showed a fundamental absorption edge near 1 eV. From the analysis of the absorption spectrum, we found that the value of the absorption edge energy is approximately 1.2 eV for a K8Ga8Si38 clathrate crystal.

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