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Abstract: Atomic-scale wetting governs material formation at the nanoscale but remains poorly understood under confinement, where classical capillarity models fail. The growth of metallic nanowires within multi-wall carbon nanotubes (MWCNTs) exemplifies this challenge, requiring precise control over wetting, nucleation, and vapour-phase condensation. Here we show that nanowire formation proceeds through a two-stage mechanism: curvature-driven nucleation at open tube ends followed by capillary-driven elongation sustained by continuous vapour condensation. Using in situ atomic-resolution transmission electron microscopy (ARTEM) coupled with a deep learning convolutional neural network (CNN) capable of classifying liquid, solid and intermediate SnxO phase transitions, we directly capture the cascade of thermally induced nanowire growth within CNTs. Growth requires a wetting interface (contact angle, θ <90°) between liquid SnxO and the nanotube wall—conditions not described by Kelvin or Lucas–Washburn models. These results establish a predictive framework for vapour-phase nanowire encapsulation, linking nanoscale wetting dynamics to the fabrication of advanced nanomaterials.

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Abstract: This thesis presents a comprehensive investigation into the ultrasound-assisted processing of Al alloys and graphite materials using ultrafast synchrotron X-ray imaging and megahertz (MHz) X-ray free electron laser (XFEL) microscopy techniques, with emphasis on understanding the multiscale and multiphysics mechanisms driving multiphase evolution of Al alloy in solidification and the layer exfoliation of graphite materials. The unifying theme is the exploration of how ultrasonically generated physical phenomena, i.e., cavitation, shockwaves, and acoustic streaming, govern microstructural evolution at multiple scales. This comparative approach provides a comprehensive understanding of ultrasound-matter interactions, revealing universal principles that can be applied to optimize processing parameters for a wide range of materials. The key findings are summarized as follows:(1) In-situ synchrotron X-ray tomography and diffraction revealed, for the first time, the nucleation and co-growth dynamics of multiple Fe-rich intermetallics and their dynamic interactions with the Al dendrites of the recycled Al-5Cu-1.5Fe-1Si alloy in solidification under ultrasound melting processing (USMP). USMP significantly refined the α-Al dendrites, modified the morphologies of α-Fe and β-Fe phases, and altered their spatial distributions, thereby enhancing structural homogeneity and potentially improving mechanical properties. (2) By taking the full advantage of MHz XFEL microscopy, we have imaged and quantified, at ns time scale and μm length scale simultaneously, the local shockwaves produced by the implosion of a single cavitation bubble, multiple bubbles and bubble clouds, as well as the layer exfoliation dynamics under such shockwave impacts. The results confirmed that exfoliation is governed not by a single implosion event, but by repeated cyclic forces induced by shockwave impact, with exfoliation behaviour strongly dependent on local defects and graphite structure. (3) Using quasi-simultaneous synchrotron X-ray tomography and diffraction, we have studied in-situ the complicated peritectic reaction mechanisms involving Al4Mn and Al6Mn phases in an Al-8Mn alloy during the solidification process. The real-time evolution of the spatial and orientation relationships between these intermetallics was quantified for the first time, revealing the highly anisotropic faceted growth and intricate coalescence patterns that deviated from the equilibrium solidification models.

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Abstract: A correlative multi-technique approach, including electron microscopy and X-ray synchrotron work, has been used to obtain both structural and compositional information of a sulfur-bearing serpentine identified in several carbonaceous chondrites (Winchcombe CM2, Aguas Zarcas CM2, Ivuna CI, and Orgueil CI), and in Ryugu samples returned by the Hayabusa2 mission. S-K edge X-ray absorption spectroscopy was used to determine the oxidation state of sulfur in the serpentine in all samples except Ryugu. The abundance of this phase varies across these samples, with the largest amount in Winchcombe; ~12 vol% of phyllosilicates are identified as sulfur-bearing serpentine characterized by ~10 wt% SO3 equivalent. HRTEM studies reveal a d001-spacing range of 0.64–0.70 nm across all sulfur-bearing serpentine sites, averaging 0.68 nm, characteristic of serpentine. Sulfur-serpentine has variable S6+/ΣStotal values and different sulfur species dependent on specimen type, with CM sulfur-bearing serpentine having values of 0.1–0.2 and S2− as the dominant valency, and CIs having values of 0.9–1.0 with S6+ as the dominant valency. We suggest sulfur is structurally incorporated into serpentine as SH− partially replacing OH−, and trapped as SO42− ions, with an approximate mineral formula of (Mg Fe2+ Fe3+ Al)2-3(Si Al)2O5(OH)5-6(HS−)1-2(SO4)2−0.1-0.7. We conclude that much of the material identified in previous studies of carbonaceous chondrites as TCI-like or PCPs could be sulfur-bearing serpentine. The relatively high abundance of sulfur-bearing serpentine suggests that incorporation of sulfur into this phase was a significant part of the S-cycle in the early Solar System.

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Abstract: The high optoelectronic quality of halide perovskites makes them suitable for use in optoelectronic devices and, recently, in emerging quantum emission applications. Advancements in perovskite nanomaterials have led to the discovery of processes in which luminescence decay times are below 100 picoseconds, stimulating the exploration of even faster radiative rates for advanced quantum applications, which have only been realized in III–V materials grown using costly epitaxial growth methods. Here we discovered ultrafast quantum transients with timescales of around two picoseconds at low temperature in bulk formamidinium lead iodide films grown via scalable solution or vapour approaches. Using a multimodal strategy, combining ultrafast spectroscopy, optical and electron microscopy, we show that these transients originate from quantum tunnelling in nanodomain superlattices. The outcome of the transient decays, that is, photoluminescence, mirrors the photoabsorption of the states, with an ultranarrow linewidth at low temperature that can reach <2 nm (~4 meV). Localized correlation of the emission and structure reveals that the nanodomain superlattices are formed by alternating ordered layers of corner-sharing and face-sharing octahedra. This discovery opens new applications leveraging intrinsic quantum properties and demonstrates powerful multimodal approaches for quantum investigations.

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Abstract: Chemical vapour deposition enables large-domain growth of ideal graphene, yet many applications of graphene require the controlled inclusion of specific defects. We present a one-step chemical vapour deposition procedure aimed at retaining the precursor topology when incorporated into the grown carbonaceous film. When azupyrene, the molecular analogue of the Stone–Wales defect in graphene, is used as a precursor, carbonaceous monolayers with a range of morphologies are produced as a function of the copper substrate growth temperature. The higher the substrate temperature during deposition, the closer the resulting monolayer is to ideal graphene. Analysis, with a set of complementary materials characterisation techniques, reveals morphological changes closely correlated with changes in the atomic adsorption heights, network topology, and concentration of 5-/7-membered carbon rings. The engineered defective carbon monolayers can be transferred to different substrates, potentially enabling applications in nanoelectronics, sensorics, and catalysis.