Electronic structure analyses of BN network materials using high energy-resolution spectroscopy methods based on transmission electron microscopy.
Microsc Res Tech
; 69(7): 531-7, 2006 Jul.
Article
en En
| MEDLINE
| ID: mdl-16718665
ABSTRACT
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 pi and pi+sigma plasmon energies of BN nanotubes (BNT) were smaller than those of h-BN. The pi+sigma 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 degrees 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.
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Base de datos:
MEDLINE
Asunto principal:
Espectrometría por Rayos X
/
Boro
/
Nanotubos
/
Energía Filtrada en la Transmisión por Microscopía Electrónica
/
Nitrógeno
Idioma:
En
Revista:
Microsc Res Tech
Asunto de la revista:
DIAGNOSTICO POR IMAGEM
Año:
2006
Tipo del documento:
Article