Browsing by Author "Mudie, ST"
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- ItemThe mechanical performance of carbon fibres-addressing the role of microstructure(Society for the Advancement of Material and Process Engineering, 2019-05-20) Lynch, P; Creighton, C; Fox, D; Santiago, PM; Hawley, A; Mudie, STCopyright 2019. Used by the Society of the Advancement of Material and Process Engineering with permission. A new SAXS-WAXS method has been developed at the Australian synchrotron for the structural analysis of carbon fibres. The new technique, referred to as serial SAXS-WAXS fibre scattering is used to map the microstructural properties of single carbon fibres, ranging in diameter from 5 to 8 µm. Based on an automated scanning protocol, a single carbon fibre is mounted in vacuum and aligned relative to the incident X-ray beam. After (automated) alignment points on each monofilament are acquired. In the forward scattering direction both the SAXS and WAXS signal are recorded as a single image to ensure that the fibre scattering cross-section is known precisely. Under these conditions both the size and alignment of the microstructural features from fibre-to-fibre are quantified. Importantly, the graphitic alignment, spacing and apparent crystallite size can be directly related to the macroscopic fibre modulus. In addition, quantitative analysis of the SAXS scattering signal from pores trapped within the fibre provides an indication of macroscopic strength. The utility of these techniques are demonstrated for carbon fibres prepared on the Carbon Nexus single tow line at 3 different carbonization tensions. © 2019 The Authors.
- ItemMicro-computed tomography beamline of the Australian synchrotron: micron-size spatial resolution X-ray imaging(MDPI, 2023-01-18) Arhatari, BD; Stevenson, AW; Thompson, D; Walsh, A; Fiala, T; Ruben, G; Afshar, N; Ozbilgen, S; Feng, TT; Mudie, ST; Tissa, PThe first new beamline of the BRIGHT project—involving the construction of eight new beamlines at the Australian Synchrotron—is the Micro-Computed Tomography (MCT) beamline. MCT will extend the facility’s capability for higher spatial resolution X-ray-computed tomographic imaging allowing for commensurately smaller samples in comparison with the existing Imaging and Medical Beamline (IMBL). The source is a bending-magnet and it is operating in the X-ray energy range from 8 to 40 keV. The beamline provides important new capability for a range of biological and material-science applications. Several imaging modes will be offered such as various X-ray phase-contrast modalities (propagation-based, grating-based, and speckle-based), in addition to conventional absorption contrast. The unique properties of synchrotron radiation sources (high coherence, energy tunability, and high brightness) are predominantly well-suited for producing phase contrast data. An update on the progress of the MCT project in delivering high-spatial-resolution imaging (in the order of micron size) of mm-scale objects will be presented in detail with some imaging results from the hot-commissioning stage. © 2023 The Authors.
- ItemMillisecond structural dynamics during the piezoelectric cycle of silk fibroin by synchrotron Xray scattering & comparison with DFT calculation(2021-08-14) Garvey, CJ; Mudie, ST; Music, D; Olsson, PAT; Sencadas, VWhile simple associations exist between piezoelectric properties and processing history, there is considerable scope for design of materials based on a more detailed molecular understanding of the re-arrangements that underpin the piezoelectric phenomenon in silk fibroin.[1] Crystallinity, and the two-phase model of semi-crystalline model of polymers, are often used to understand the properties of protein based materials where there is considerable thermodynamic drive to short range ordering of polymer chains, folding, which is not present in melt processed thermoplastics. Our investigations aim to probe the relationship between structure and dynamics in silk fibroin based materials and correlate these with the piezo-electric signal. Recently, we have used a triggered and summative data acquisition scheme to synchronise X-ray scattering data collection with a piezoelectric cycle of a compressed electro-spun fibroin mat.[2] This mode enabled a steady perturbed state to be sampled. The summation of the scattering patten from this state across multiple cycles provides superior statistics than could be achieved by sampling a single cycle. The setup is shown in Figure 1A. At rest this poorly ordered system exhibits a limited number of very broad peaks but quite a high degree of chain folding.[3] With compression there is marked increase in the scattered intensity, both in the small (SAXS) and the wide (WAXS) angle regimes, as well as a shift and reduction in broadness of the WAXS peaks (Figure 1B). We interpret the increase in the SAXS signal as an increase in scattering from grain boundaries and the WAXS as the formation of new crystalline domains. However, the limited number of very broad diffraction peaks make these data unsuitable for structural determination. In order to provide an alternative, but complementary, perspective on the structural dynamics and the nature of the potential surface along which the polymer folds, during the piezo cycle we have turned to a computation approach. Density functional theory (DFT) calculations were performed within the framework of the projector augmented wave potentials parametrised by Perdew et al., [3] and the Tkatchenko-Scheffler correction [4] with a self-consistent screening to account for the weak correlations. Full structural optimisation of orthorhombic C20O8N8H32 was performed. The calculated lattice parameters (a = 9.409 Å, b = 6.984 Å, c = 9.221 Å) and the corresponding diffraction pattern (black vertical lines) are compared with the experimental data in Figure 1C. © The Authors
- ItemPolymers with cavities tuned for fast selective transport of small molecules and ions(American Association for the Advancement of Science, 2007-10-12) Park, HB; Jung, CH; Lee, YM; Hill, AJ; Pas, SJ; Mudie, ST; van Wagner, E; Freeman, BD; Cookson, DJWithin a polymer film, free-volume elements such as pores and channels typically have a wide range of sizes and topologies. This broad range of free-volume element sizes compromises a polymer's ability to perform molecular separations. We demonstrated free-volume structures in dense vitreous polymers that enable outstanding molecular and ionic transport and separation performance that surpasses the limits of conventional polymers. The unusual microstructure in these materials can be systematically tailored by thermally driven segment rearrangement. Free-volume topologies can be tailored by controlling the degree of rearrangement, flexibility of the original chain, and judicious inclusion of small templating molecules. This rational tailoring of free-volume element architecture provides a route for preparing high-performance polymers for molecular-scale separations. © 2007, American Association for the Advancement of Science
- ItemPositron annihilation lifetime study of radiation-damaged natural zircons(Elsevier B.V., 2016-04-01) Roberts, J; Gaugliardo, PR; Farnan, I; Zhang, M; Vance, ER; Davis, J; Karatchevtseva, I; Knott, RB; Mudie, ST; Buckman, J; Sullivan, JPZircons are a well-known candidate waste form for actinides and their radiation damage behaviour has been widely studied by a range of techniques. In this study, well-characterised natural single crystal zircons have been studied using Positron Annihilation Lifetime Spectroscopy (PALS). In some, but not all, of the crystals that had incurred at least half of the alpha-event damage of ∼1019 α/g required to render them structurally amorphous, PALS spectra displayed long lifetimes corresponding to voids of ∼0.5 nm in diameter. The long lifetimes corresponded to expectations from published Small-Angle X-ray Scattering data on similar samples. However, the non-observation by PALS of such voids in some of the heavily damaged samples may reflect large size variations among the voids such that no singular size can be distinguished or. Characterisation of a range of samples was also performed using scanning electron microscopy, optical absorption spectroscopy, Raman scattering and X-ray scattering/diffraction, with the degree of alpha damage being inferred mainly from the Raman technique and X-ray diffraction. The observed void diameters and intensities of the long lifetime components were changed somewhat by annealing at 700 °C; annealing at 1200 °C removed the voids entirely. The voids themselves may derive from He gas bubbles or voids created by the inclusion of small quantities of organic and hydrous matter, notwithstanding the observation that no voidage was evidenced by PALS in two samples containing hydrous and organic matter. © 2016 Elsevier B.V.
- ItemPretreatment control of carbon nanotube array growth for gas separation: alignment and growth studied using microscopy and small-angle x-ray scattering(Americal Chemical Society, 2013-04-24) Yang, XS; Yuan, LX; Peterson, VK; Minett, AI; Zhao, MW; Kirby, N; Mudie, ST; Harris, ATAligned multiwalled carbon nanotube (CNT) arrays were prepared using chemical vapor deposition of C2H4 on Fe catalyst at 750 degrees C. CNT array height and alignment depends strongly on the duration of H-2 pretreatment, with optimal height and alignment achieved using 10-15 min pretreatment. Small-angle X-ray scattering (SAXS) was used to quantify the alignment, distribution, and size of the CNTs in arrays produced from varying pretreatment times and the results correlated with microscopy measurements. SAXS analysis revealed that the higher section of the CNT arrays exhibited better alignment than the lower section. Combining these insights with transmission electron microscopy measurements of the CNT defects within each array enable a mechanism for the CNT growth to be proposed, where the loss of alignment arises from deformation of the CNTs during their growth. Gas permeation test across densified CNT arrays indicated that the alignment of the CNT array plays an important role in the gas transport, and that the gas diffusion across the well-aligned CNT arrays was enhanced by a factor of 45, which is much more than that across the poorly aligned CNT arrays, with an enhancement factor of similar to 8. © 2013, American Chemical Society.
- ItemSimultaneous reconstruction and structural fitting of the complex atomic fine structure of copper and iron(Australian Institute of Physics, 2022-12-11) Di Pasquale, P; Tran, CQ; Chantler, CT; Barnea, Z; Kirk, T; Dao, MN; Balaur, E; van Riessen, GA; Hinsley, GN; Jallandhra, A; Ceddia, J; Rogers, J; Kewish, CM; Paterson, DJ; Reinhardt, J; Kirby, N; Mudie, STA novel technique for determining complex atomic fine structure will be described. Exciting applications of the technique such as a phase analogue to x-ray absorption fine structure applications will also be discussed.