Valence Electron and Chemical State Analysis of Be₁₂M (M = Ti, V) Beryllides by Soft X-ray Emission Spectroscopy

Abstract

Be-rich intermetallics (beryllides) have gathered wide attentions to be adopted for high temperature environments, such as an advanced neutron multiplier in fusion reactors. This study reveals the valence electron structure of Be 12 M (M = Ti,V) by using soft X-ray emission spectroscopy with ultra-high resolution (~0.22 eV). The Be-K spectra from the Be 12 M phases show significantly lower densities of the occupied states near the Be-K edge than thaose of metallic beryllium. Theoretical calculations indicate that changes in the valence electron structure are derived from the large downward shift of the Fermi level in Be 12 M, by at least 0.8 eV. Based on the knowledge of the valence electron structures and the chemical shift, chemical state mappings of BeO and Be 12 V in the oxidized beryllide specimen were successfully obtained. The approach is applicable for visualization and identification of metallic/oxidized phase in light-element compounds by electron microscope.

Occupied Electronic States of Li in Li, Li2O2, and Li2O Analyzed by Soft X-ray Emission Spectroscopy

“…We note that Li valence electron structures must be determined experimentally for understanding the nature of chemical bonds and identifying oxide phases with Li. High-resolution K-edge spectral data can be exploited to visualize chemical state mapping on a microscopic scale, as demonstrated in our previous studies for Be ( Z = 4) and B ( Z = 5) compounds. , Thus, in this study, the ultrahigh-energy-resolution (∼0.2 eV) valence electron structures of Li in Li, Li 2 O 2 , and Li 2 O were experimentally analyzed. We employ SXES with a highly sensitive X-ray charge-coupled device attached to an electron probe microanalyzer (EPMA). , SXES is a bulk-sensitive measurement that covers ultrasoft X-rays in the energy range of 50–170 eV, including Li–K emission at 54.1 eV (i.e., 2p → 1s transition in Li).…”

“…High-resolution K-edge spectral data can be exploited to visualize chemical state mapping on a microscopic scale, as demonstrated in our previous studies for Be (Z = 4) and B (Z = 5) compounds. 16,17 Thus, in this study, the ultrahigh-energyresolution (∼0.2 eV) valence electron structures of Li in Li, Li 2 O 2 , and Li 2 O were experimentally analyzed. We employ SXES with a highly sensitive X-ray charge-coupled device attached to an electron probe microanalyzer (EPMA).…”

In situ quantitative analysis of beryllium by EPMA: analytical conditions and further insights into beryllium geochemistry

“…4b-f), which may be attributed to the decreased E L of the Fermi level in Be-O bonds. 48 The OH or H 2 O in minerals are known to not be determined by EPMA, resulting in low total weight for hydrous minerals. 37 Both OH and H 2 O in minerals are considered volatile components, but these components will be dehydrated under high accelerating voltage and beam current in the processes of elemental analyses.…”

Chemical State Mapping of p/n-Controlled SrB6 Bulk Specimens by Soft X-ray Emission Electron Microscope

“…The peak energy positions (vertical arrows) and the shoulder structures (vertical lines) of the B K of these materials are different from each other, reflecting different chemical bonding states owing to different crystal structures. By using a high energy resolution, elemental and chemical state analyses and those mappings are possible [5][6][7][26][27][28][29][30]. The emission due to the process d is also affected by the chemical state of the materials [31,32].…”