Nanoscale imaging of Li and B in nuclear waste glass, a comparison of ToF-SIMS, NanoSIMS, and APT

Chemical Analysis for Alkali Ion-exchanged Glass Using Atom Probe Tomography

The developing flexible ultrathin glass for use in foldable displays has attracted widespread attention as an alternative to rigid electronic smartphones. However, the detailed compositional effects of chemically strengthened glass are not well understood. Moreover, the spatially resolved chemistry and depth of the compression layer of tempered glass are far from clear. In this study, commonly used X-ray spectroscopy techniques and atom probe tomography (APT) were used comparatively to investigate the distribution of constituent elements in two representative smartphone glass samples: non- and chemically tempered. APT has enabled sub-nanoscale analyses of alkali metals (Li, Na, K, and Ca) and this demonstrates that APT can be considered as an alternative technique for imaging the chemical distribution in glass for mobile applications.

Characterization of the boron profile and coordination in altered glass layers by EEL spectroscopy

Electron energy-loss spectroscopy was used to characterize the boron profile and its coordination (B^III and B^IV), along the complex alteration layer of glass samples altered for 511 days at 50 °C in solution containing FeCl₂, MgCl₂ and/or CaCl₂. To reach this goal, the impact of both TEM operating conditions and sample preparation on the determination of the boron coordination was first studied using mineralogical and pristine glasses reference samples. Then, the boron concentration profiles were characterized in the glass alteration layer. These profiles were found to be S-shaped with a thickness around forty nanometers. The proportion of B^III was found to decrease with the boron total concentration (from the pristine glass to the gel layer), which suggests a higher bonding strength for B^IV bonds than that of B^III bonds under the alteration conditions. These findings are of tremendous interest to advance further in the understanding of glass alteration mechanisms.

NanoSIMS Imaging and Analysis in Materials Science

High-resolution SIMS analysis can be used to explore a wide range of problems in material science and engineering materials, especially when chemical imaging with good spatial resolution (50-100 nm) can be combined with efficient detection of light elements and precise separation of isotopes and isobaric species. Here, applications of the NanoSIMS instrument in the analysis of inorganic materials are reviewed, focusing on areas of current interest in the development of new materials and degradation mechanisms under service conditions. We have chosen examples illustrating NanoSIMS analysis of grain boundary segregation, chemical processes in cracking, and corrosion of nuclear components. An area where NanoSIMS analysis shows potential is in the localization of light elements, in particular, hydrogen and deuterium. Hydrogen embrittlement is a serious problem for industries where safety is critical, including aerospace, nuclear, and oil/gas, so it is imperative to know where in the microstructure hydrogen is located. By charging the metal with deuterium, to avoid uncertainty in the origin of the hydrogen, the microstructural features that can trap hydrogenic species, such as precipitates and grain and phase boundaries, can be determined by NanoSIMS analysis on a microstructurally relevant scale.