In Situ EELS and TEM Observation of Boron Carbide (B₄C) During Hydrogen- and Helium-Ion Bombardments

Abstract

Increasing attention has been paid recently to boron carbide (B4C) from a viewpoint of plasma-facing materials in a fusion device. This paper reports structural change of B4C observed in situ by EELS and TEM during hydrogen-and helium-ion bombardments at room temperature. The B4C 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 sp2 type bonding between constituent carbon atoms by the ion bombardments.