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Two-micron thick erbium oxide tritium barrier coatings have been prepared by aerosol injection chemical vapor deposition and subsequently irradiated with 33 MeV Au 6+ ions at fluences up to 2.1 × 1016 Au/m2 at 550°C. Scanning electron microscopy, X-ray diffraction and transmission electron microscopy were used to investigate the coating surface morphologies, phase structures and cross-sectional microstructures as a function of irradiation and thermal treatment. XRD data was also used to extract information about the evolution of lattice strain in the coating. Some of the cubic erbia transformed to the monoclinic phase in the sample that was ion irradiated at temperature, and this was accompanied by a change from columnar to a more equiaxed grain structure. All coatings were found to experience out-of-plane tensile strain, thought to originate from thermal stresses created during coating manufacture. Thermal treatment reduced microstrains present in the asdeposited sample, whilst the cubic-to-monoclinic phase transformation reduced strain in the cubic phase but increased strain in the monoclinic phase. [ABSTRACT FROM AUTHOR]

• Complementary characterisation of internal interfaces in a diverse range of materials. • Segregation of solutes to grain boundaries characterised using atom probe tomography. • Grain boundaries' five macroscopic degrees of freedom determined from TKD data. Changes in the chemistry of internal interfaces, particularly grain boundaries, are known to affect the macroscopic properties of a wide range of material systems. Solute segregation to grain boundaries is dependent on, amongst other factors, the physical structure of the grain boundary. We demonstrate how complementary use of transmission Kikuchi diffraction (TKD) and atom probe tomography (APT) can provide a more holistic characterisation of grain boundaries in a variety of materials. Structural information is reported from TKD data for a model steel, a titanium alloy, and a multicrystalline silicon sample. Complementary APT analyses are used to determine the segregation behaviour to these interfaces. A novel specimen preparation protocol allows for the grain boundary to be positioned more reliably within the apex of an APT specimen. Meanwhile, a method that allows a grain boundary's five macroscopic degrees of freedom to be determined from TKD data alone is also proposed. [ABSTRACT FROM AUTHOR]

As hydrogen is touted as a key player in the decarbonization of modern society, it is critical to enable quantitative hydrogen (H) analysis at high spatial resolution and, if possible, at the atomic scale. H has a known deleterious impact on the mechanical properties (strength, ductility, toughness) of most materials that can hinder their use as part of the infrastructure of a hydrogen-based economy. Enabling H mapping including local hydrogen concentration analyses at specific microstructural features is essential for understanding the multiple ways that H affect the properties of materials including embrittlement mechanisms and their synergies. In addition, spatial mapping and quantification of hydrogen isotopes is essential to accurately predict tritium inventory of future fusion power plants thus ensuring their safe and efficient operation. Atom probe tomography (APT) has the intrinsic capability to detect H and deuterium (D), and in principle the capacity for performing quantitative mapping of H within a material's microstructure. Yet, the accuracy and precision of H analysis by APT remain affected by complex field evaporation behavior and the influence of residual hydrogen from the ultrahigh vacuum chamber that can obscure the signal of H from within the material. The present article reports a summary of discussions at a focused workshop held at the Max-Planck Institute for Sustainable Materials in April 2024. The workshop was organized to pave the way to establishing best practices in reporting APT data for the analysis of H. We first summarize the key aspects of the intricacies of H analysis by APT and then propose a path for better reporting of the relevant data to support interpretation of APT-based H analysis in materials., Competing Interests: Conflict of Interest The authors declare that they have no competing interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Microscopy Society of America.)