High energy-resolution electron energy-loss spectroscopy study of the dielectric properties of bulk and nanoparticle LaB6 in the near-infrared region

Yohei Sato; Masami Terauchi; Masaki Mukai; Toshikatsu Kaneyama; Kenji Adachi

doi:10.1016/j.ultramic.2011.05.003

High energy-resolution electron energy-loss spectroscopy study of the dielectric properties of bulk and nanoparticle LaB6 in the near-infrared region

Ultramicroscopy. 2011 Jul;111(8):1381-7. doi: 10.1016/j.ultramic.2011.05.003. Epub 2011 May 14.

Authors

Yohei Sato¹, Masami Terauchi, Masaki Mukai, Toshikatsu Kaneyama, Kenji Adachi

Affiliation

¹ Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Sendai 980-8577, Japan. y-sato@tagen.tohoku.ac.jp

PMID: 21864781
DOI: 10.1016/j.ultramic.2011.05.003

Abstract

The dielectric properties of LaB(6) crystals and the plasmonic behavior of LaB(6) nanoparticles, which have been applied to solar heat-shielding filters, were studied by high energy-resolution electron energy-loss spectroscopy (HR-EELS). An EELS spectrum of a LaB(6) crystal showed a peak at 2.0 eV, which was attributed to volume plasmon excitation of carrier electrons. EELS spectra of single LaB(6) nanoparticles showed peaks at 1.1-1.4 eV depending on the dielectric effect from the substrates. The peaks were assigned to dipole oscillation excitations. These peak energies almost coincided with the peak energy of optical absorption of a heat-shielding filter with LaB(6) nanoparticles. On the other hand, those energies were a smaller than a dipole oscillation energy predicted using the dielectric function of bulk LaB(6) crystal. It is suggested that the lower energy than expected is due to an excitation at 1.2 eV, which was observed for oxidized LaB(6) area.