Free Access
Microsc. Microanal. Microstruct.
Volume 6, Number 1, February 1995
Page(s) 149 - 157
Microsc. Microanal. Microstruct. 6, 149-157 (1995)
DOI: 10.1051/mmm:1995115

In Situ EELS and TEM Observation of Boron Carbide ${\bf (B}_{{\bf 4}}{\bf C)}$ During Hydrogen- and Helium-Ion Bombardments

Kouhei N. Kushita1, Kiichi Hojou2 et Shigemi Furuno2

1  Department of Radioisotopes, Japan Atomic Energy Research Institute Tokai-mura, Naka-gun, Ibaraki-ken, 319-11, Japan
2  Department of Materials Science and Technology, Japan Atomic Energy Research Institute Tokai-mura, Naka-gun, Ibaraki-ken, 319-11, Japan

Increasing attention has been paid recently to boron carbide $\rm (B_4C)$ from a viewpoint of plasma-facing materials in a fusion device. This paper reports structural change of $\rm B_4C$ observed in situ by EELS and TEM during hydrogen- and helium-ion bombardments at room temperature. The $\rm B_4C$ became amorphous by the ion bombardments. This amorphization process was presented as a function of the shift of plasmon-loss peak energy and the change of core-loss profiles in addition to electron diffraction patterns. Analysis of core-loss peaks for boron as well as for carbon in B4C during amorphization process revealed the formation of $\rm sp^2$ type bonding between constituent carbon atoms by the ion bombardments.

2852F - Fusion reactor materials.
7920K - Other electron surface impact phenomena.
6180M - Channelling, blocking and energy loss of particles.
6180J - Ion beam effects.
6140 - Structure of amorphous and polymeric materials.
6470K - Solid solid transitions.
7145G - Exchange, correlation, dielectric and magnetic functions, plasmons.
3520G - Molecular bond strengths, dissociation energies, hydrogen bonding.

Key words
amorphisation -- bonds chemical -- boron compounds -- electron diffraction -- electron energy loss spectra -- fusion reactor materials -- helium ions -- hydrogen ions -- ion beam effects -- plasmons -- positive ions -- transmission electron microscopy -- in situ EELS -- in situ TEM -- ion bombardment -- plasma facing materials -- fusion device -- structural change -- room temperature -- amorphization process -- plasmon loss peak energy -- core loss profiles -- electron diffraction patterns -- sp sup 2 type bonding -- H sub 2 sup + -- He sup + -- 293 K -- H -- He -- B sub 4 C

© EDP Sciences 1995