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Electronic structure analyses of BN network materials using high energy‐resolution spectroscopy methods based on transmission electron microscopy
Author(s) -
Terauchi M.
Publication year - 2006
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/jemt.20323
Subject(s) - electron energy loss spectroscopy , transmission electron microscopy , plasmon , high resolution transmission electron microscopy , materials science , spectroscopy , emission spectrum , boron nitride , molecular physics , spectral line , analytical chemistry (journal) , chemistry , atomic physics , physics , nanotechnology , optoelectronics , chromatography , quantum mechanics , astronomy
Electronic structures of boron‐nitride (BN) nanotubes and a BN cone‐structure material were studied by using a high energy‐resolution electron energy‐loss spectroscopy (EELS) microscope. A trial of the whole electronic structure study of hexagonal BN (h‐BN), which consists of flat BN honeycomb layers, was conducted by a combination of EELS and X‐ray emission spectroscopy (XES) based on transmission electron microscopy (TEM) (TEM‐EELS/XES). The π and π+σ plasmon energies of BN nanotubes (BNT) were smaller than those of h‐BN. The π+σ energy was explained by the surface plasmon excitation. The spectrum of a two‐wall BNT of 2.7 nm in diameter showed a new spectral onset at 4 eV. The valence electron excitation spectra obtained from the tip region of the BN cone with an apex angle of 20° showed similar intensity distribution with those of BNTs. The B K‐shell electron excitation spectra obtained from the bottom edge region of the BN cone showed additional peak intensity when compared with those of h‐BN and BNT. The B K‐shell electron excitation spectra and B K‐emission spectra of h‐BN were compared with a result of a LDA band calculation. It showed that high symmetry points in the band diagram appear as peak and/or shoulder structures in the EELS and XES spectra. Interband transitions appeared in the imaginary part of the dielectric function of h‐BN experimentally obtained were assigned in the band diagram. The analysis also presented that the LDA calculation estimated the bandgap energy smaller than the real material by an amount of 2 eV. Those results of TEM‐EELS/XES analysis presented that high energy‐resolution spectroscopy methods combined with TEM is a promising method to analyze whole electronic structures of nanometer scale materials. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.