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

Abstract

Abstract. 2014 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.

Defects in an orthorhombic MoAlB MAB phase thin film grown at moderate synthesis temperature

“…The energy-loss near-edge structure (ELNES) of the B K edge illustrates transitions from 1s to unoccupied π* states (sharp peak A) and σ* states (peak B) while peak C can be an effect of plasmon contributions. 42,43 The onset of the B K edge is roughly identical for all defects, starting from 186.8 eV. A minute splitting of peak A was noticed at the faceted grain boundary structure.…”

“…In the depicted energy loss regime in Fig.5(e), the element-specific edges of B K ( peak A, B, C) and Mo M 4,5 (marked by the red arrow) are present. The energy-loss near-edge structure (ELNES) of the B K edge illustrates transitions from 1s to unoccupied π* states (sharp peak A) and σ* states ( peak B) while peak C can be an effect of plasmon contributions 42,43. The onset of the B K edge is roughly identical for all defects, starting from 186.8 eV.…”

In‐situ Scanning Transmission X‐Ray Microscopy of Catalytic Solids and Related Nanomaterials

“…[36] In-situ sample treatments like ion bombardments have also been reported for TEM-EELS experiments. [37] For a recent detailed comparison between TEM and TXM we refer to a review as provided by Hitchcock et al [38] A combined X-ray and electron microscope design is the socalled X-ray photoemission electron microscopes (PEEM) [39][40][41] which uses a full field X-ray beam and the detection of the electrons emitted from the sample surface. Because X-PEEM uses electron detection, experiments under gas atmosphere are not possible.…”

Impact scenarios in boron carbide: A computational study

“…This does not affect nano-crystallinity 15,16 , although micropores are observed. Amorphisation is possible using H + ion radiation, which alters the structure chemically 17 , but 1MeV electron impacts again do not affect the gross crystal structure 18 ; 2MeV impacts are required to induce amorphisation through impact.…”