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788 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I13-2-Diamond Manchester Imaging	Evaluating the morphology of the degradation layer of pure magnesium via 3D imaging at resolutions below 40 nm Berit Zeller-Plumhoff , Daniel Laipple , Hanna Slominska , Kamila Iskhakova , Elena Longo , Alexander Hermann , Silja Flenner , Imke Greving , Malte Storm , Regine Willumeit-Römer Bioactive Materials 6, 4368 - 4376 DOI: 10.1016/j.bioactmat.2021.04.009 Diamond Proposal Number(s): [22346, 21697] Open Access Show Abstract ▼ Abstract: Magnesium is attractive for the application as a temporary bone implant due to its inherent biodegradability, non-toxicity and suitable mechanical properties. The degradation process of magnesium in physiological environments is complex and is thought to be a diffusion-limited transport problem. We use a multi-scale imaging approach using micro computed tomography and transmission X-ray microscopy (TXM) at resolutions below 40 nm. Thus, we are able to evaluate the nanoporosity of the degradation layer and infer its impact on the degradation process of pure magnesium in two physiological solutions. Magnesium samples were degraded in simulated body fluid (SBF) or Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum (FBS) for one to four weeks. TXM reveals the three-dimensional interconnected pore network within the degradation layer for both solutions. The pore network morphology and degradation layer composition are similar for all samples. By contrast, the degradation layer thickness in samples degraded in SBF was significantly higher and more inhomogeneous than in DMEM+10%FBS. Distinct features could be observed within the degradation layer of samples degraded in SBF, suggesting the formation of microgalvanic cells, which are not present in samples degraded in DMEM+10%FBS. The results suggest that the nanoporosity of the degradation layer and the resulting ion diffusion processes therein have a limited influence on the overall degradation process. This indicates that the influence of organic components on the dampening of the degradation rate by the suppression of microgalvanic degradation is much greater in the present study.	Dec 2021
B18-Core EXAFS	Synthesis and thermodynamics of uranium-incorporated α-Fe2O3 nanoparticles Andy Lam , Forrest Hyler , Olwen Stagg , Katherine Morris , Samuel Shaw , Jesús M. Velázquez , Alexandra Navrotsky Journal Of Nuclear Materials 556 DOI: 10.1016/j.jnucmat.2021.153172 Diamond Proposal Number(s): [17243] Show Abstract ▼ Abstract: Hematite nanoparticles were synthesized with U(VI) in circumneutral water through a coprecipitation and hydrothermal treatment process. XRD, TEM, and EXAFS analyses reveal that uranium may aggregate along grain boundaries and occupy Fe sites within hematite. The described synthesis method produces crystalline, single-phase iron oxide nanoparticles absent of surface-bound uranyl complexes. EXAFS data were comparable to spectra from existing studies whose syntheses were more representative of naturally occurring, extended aging processes. This work provides and validates an accelerated method of synthesizing uranium-immobilized iron oxide nanoparticles for further mechanistic studies. High temperature oxide melt solution calorimetry measurements were performed to calculate the thermodynamic stability of uranium-incorporated iron oxide nanoparticles. Increasing uranium content within hematite resulted in more positive formation enthalpies. Standard formation enthalpies of UxFe2–2xO3 were as high as 76.88 ± 2.83 kJ/mol relative to their binary oxides, or -764.04 ± 3.74 kJ/mol relative to their constituent elements, at x = 0.037. Data on the thermodynamic stability of uranium retention pathways may assist in predicting waste uranyl remobilization, as well as in developing more effective methods to retain uranium captured from aqueous environments.	Dec 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Structural and electrochemical properties of type VIII Ba8Ga16−δSn30+δ clathrate (δ ≈ 1) during lithiation Andrew Dopilka , Amanda Childs , Alexander Ovchinnikov , Ran Zhao , Svilen Bobev , Xihong Peng , Candace Chan Acs Applied Materials & Interfaces DOI: 10.1021/acsami.1c07240 Diamond Proposal Number(s): [22209] Open Access Show Abstract ▼ Abstract: The clathrate was prepared in a Sn flux using conditions that favor the type VIII over type I clathrate structure as described previously and the composition was confirmed by single-crystal X-ray diffraction (XRD). More details can be found in the Supporting Information. Slurries containing the active material (type VIII clathrate or commercially obtained β-Sn powder), carbon black, and binder were prepared and coated onto the copper foil (see the Supporting Information). These composite electrodes were then lithiated galvanostatically in half-cells with lithium metal and then extracted for ex situ measurements. Synchrotron X-ray pair distribution (PDF) measurements were conducted at Diamond Light Source (Didcot, U.K.) at the I15-I dedicated PDF beamline with λ = 0.161669 Å. The atomic PDF, G(r), as defined by Billinge et al., was generated from the total scattering data using PDFgetx3 within the xPDF suite software package. The first-principles density functional theory (DFT) calculations were performed in a similar manner to our previous work and are described in more detail in the Supporting Information. The Gibbs free-energy change, average lithiation voltage, and formation energy were calculated as described previously. The climbing image nudged elastic band (NEB) method was used to calculate the Li migration barriers.	Sep 2021
	BaBi2O6: A promising n-type thermoelectric oxide with the pbsb2o6crystal structure Kieran B. Spooner , Alex M. Ganose , W. W. Winnie Leung , John Buckeridge , Benjamin A. D. Williamson , Robert G. Palgrave , David O. Scanlon Chemistry Of Materials 12 DOI: 10.1021/acs.chemmater.1c02164 Show Abstract ▼ Abstract: Thermoelectric materials offer the possibility of enhanced energy efficiency due to waste heat scavenging. Based on their high-temperature stability and ease of synthesis, efficient oxide-based thermoelectrics remain a tantalizing research goal; however, their current performance is significantly lower than the industry standards such as Bi2Te3 and PbTe. Among the oxide thermoelectrics studied thus far, the development of n-type thermoelectric oxides has fallen behind that of p-type oxides, primarily due to limitations on the overall dimensionless figure of merit, or ZT, by large lattice thermal conductivities. In this article, we propose a simple strategy based on chemical intuition to discover enhanced n-type oxide thermoelectrics. Using state-of-the-art calculations, we demonstrate that the PbSb2O6-structured BaBi2O6 represents a novel structural motif for thermoelectric materials, with a predicted ZT of 0.17–0.19. We then suggest two methods to enhance the ZT up to 0.22, on par with the current best earth-abundant n-type thermoelectric at around 600 K, SrTiO3, which has been much more heavily researched. Our analysis of the factors that govern the electronic and phononic scattering in this system provides a blueprint for optimizing ZT beyond the perfect crystal approximation.	Sep 2021
B18-Core EXAFS	Superior sodium storage properties in the anode material NiCr2S4 for sodium-ion batteries: An X-ray diffraction, pair distribution function, and X-ray absorption study reveals a conversion mechanism via nickel extrusion Felix Hartmann , Martin Etter , Giannantonio Cibin , Lina Liers , Huayna Terraschke , Wolfgang Bensch Advanced Materials 7 DOI: 10.1002/adma.202101576 Diamond Proposal Number(s): [20060] Open Access Show Abstract ▼ Abstract: The pseudo-layered sulfide NiCr2S4 exhibits outstanding electrochemical performance as anode material in sodium-ion batteries (SIBs). The Na storage mechanism is investigated by synchrotron-based X-ray scattering and absorption techniques as well as by electrochemical measurements. A very high reversible capacity in the 500th cycle of 489 mAh g−1 is observed at 2.0 A g−1 in the potential window 3.0–0.1 V. Full discharge includes irreversible generation of Ni0 and Cr0 nanoparticles embedded in nanocrystalline Na2S yielding shortened diffusion lengths and predominantly surface-controlled charge storage. During charge, Ni0 and Cr0 are oxidized, Na2S is consumed, and amorphous Ni and Cr sulfides are formed. Limiting the potential window to 3.0–0.3 V an unusual nickel extrusion sodium insertion mechanism occurs: Ni2+ is reduced to nanosized Ni0 domains, expelled from the host lattice, and is replaced by Na+ cations to form O3-type like NaCrS2. Surprisingly, the discharge and charge processes comprise Na+ shuttling between highly crystalline NiCr2S4 and NaCrS2 enabling a superior long-term stability for 3000 cycles. The results not only provide valuable insights for the electrochemistry of conversion materials but also extend the scope of layered electrode materials considering the reversible nickel extrusion sodium insertion reaction as new concept for SIBs.	Sep 2021
I22-Small angle scattering & Diffraction	Aged layered double hydroxide nanosheet–polyvinyl alcohol dispersions for enhanced gas barrier coating performance Jingfang Yu , Chunping Chen , James B. Gilchrist , Jean-Charles Buffet , Zhonghua Wu , Guang Mo , Fei Xie , Dermot O'Hare Materials Horizons 335 DOI: 10.1039/D1MH00433F Diamond Proposal Number(s): [17095] Open Access Show Abstract ▼ Abstract: Whilst applying a coating layer to a polymer film is a routine approach to enhance the gas barrier properties of the film, it is counter-intuitive to consider that the gas barrier performance of the film would improve by ageing the coating dispersion for weeks before application. Herein, we report that the oxygen barrier performance of a 12 μm PET film coated with a dispersion of inorganic nanosheets in polyvinyl alcohol can be significantly enhanced by ageing this coating dispersion for up to 8 weeks before application. We found up to a 37-fold decrease in the oxygen transmission rate (OTR) of the PET coated film using aged dispersions of [Mg0.66Al0.33(OH)2](NO3)0.33 layered double hydroxide nanosheets (Mg2Al-LDH NS) in polyvinyl alcohol (PVA) compared to the film coated with an equivalent freshly prepared LDH/PVA dispersion. A limiting OTR value of 0.31 cc m−2 day−1 was achieved using the PET film coated with a 3 week aged LDH NS/PVA dispersion. X-ray diffraction experiments show that the degree of in plane alignment of LDH NS on the PET film surface increased significantly from 70.6 ± 0.6 to 86.7 ± 0.6 (%) (100% represents complete alignment of LDH NS platelets on the film surface) for the 4 week aged dispersion compared to the freshly prepared layer. We postulate that when the Mg2Al-LDH NS are aged in PVA the coiled PVA aggregates start to unwrap and attach onto the Mg2Al-LDH NS through hydrogen bonding and eventually form a hydrogen bonded ordered network that facilitates the alignment of nanosheet dispersions during the coating process. Our results suggest that the ageing of inorganic nanosheet dispersions in PVA or other potential hydrogen bonding adhesive systems could be a general approach to improve the alignment of the nanosheets on the polymer film surface once applied and thus improve their performance characteristics for barrier coating applications.	Sep 2021
I15-Extreme Conditions	Pressure-induced chemical decomposition of copper orthovanadate (α-Cu3V2O8) Daniel Díaz-Anichtchenko , Robin Turnbull , Enrico Bandiello , Simone Anzellini , Srungarpu Nagabhusan Achary , Daniel Errandonea Journal Of Materials Chemistry C 43 DOI: 10.1039/D1TC02901K Show Abstract ▼ Abstract: The high pressure stability of α-Cu3V2O8 has been investigated via complementary high pressure synchrotron X-ray diffraction experiments and theoretical density functional theory calculations. The results of both experiment and theory are in close agreement. The main result of this work is that α-Cu3V2O8 undergoes a pressure-induced chemical decomposition into CuO and V2O5 at a modest pressure of ∼1.35 GPa according to the experimental observations, and at ∼2.45 GPa according to the calculations. The decomposition is investigated with enthalpy calculations and one of the main driving factors is the stability of the octhedral oxygen-coordination of the metal atoms in the decompositon products. Additionally, we determine the bulk modulus of α-Cu3V2O8 to be the lowest of all known vanadates, at 52(2) GPa, due to its crystal structure, and determine the corresponding isothermal compressibility tensor.	Sep 2021
I13-2-Diamond Manchester Imaging	Deep learning approach to assess damage mechanics of bone tissue Sabrina Chin-Yun Shen , Marta Pena Fernandez , Gianluca Tozzi , Markus J. Buehler Journal Of The Mechanical Behavior Of Biomedical Materials 4 DOI: 10.1016/j.jmbbm.2021.104761 Diamond Proposal Number(s): [22575] Show Abstract ▼ Abstract: Machine learning methods have the potential to transform imaging techniques and analysis for healthcare applications with automation, making diagnostics and treatment more accurate and efficient, as well as to provide mechanistic insights into tissue deformation and fracture in physiological and pathological conditions. Here we report an exploratory investigation for the classification and prediction of mechanical states of cortical and trabecular bone tissue using convolutional neural networks (CNNs), residual neural networks (ResNet), and transfer learning applied to a novel dataset derived from high-resolution synchrotron-radiation micro-computed tomography (SR-microCT) images acquired in uniaxial continuous compression in situ. We present the systematic optimization of CNN architectures for classification of this dataset, visualization of class-defining features detected by the CNNs using gradient class activation maps (Grad-CAMs), comparison of CNN performance with ResNet and transfer learning models, and perhaps most critically, the challenges that arose from applying machine learning methods to an experimentally-derived dataset for the first time. With optimized CNN architectures, we obtained trained models that classified novel images between failed and pristine classes with over 98% accuracy for cortical bone and over 90% accuracy for trabecular bone. Harnessing a pre-trained ResNet with transfer learning, we further achieved over 98% accuracy on the cortical dataset, and 99% on the trabecular dataset. This demonstrates that powerful classifiers for high-resolution SR-microCT images can be developed even with few unique training samples and invites further development through the inclusion of more data and training methods to move towards novel, fundamental, and machine learning-driven insights into microstructural states and properties of bone.	Aug 2021
I10-Beamline for Advanced Dichroism	Ferromagnetism in ultrathin surface-free La0.7Sr0.3MnO3 layers in electrostatically defined heterostructures A. Galdi , N. Coppola , C. Sacco , L. Maritato , P. Bencok , P. Steadman , P. Orgiani , C. Aruta Physical Review Materials 5 DOI: 10.1103/PhysRevMaterials.5.084409 Diamond Proposal Number(s): [14915] Show Abstract ▼ Abstract: Electrostatically defined perovskite oxide heterostructures, in which carriers are confined by the modulation of the A-site ion charge, offer new possibilities of tuning the magnetic properties of manganite oxides. We investigate the preferential orientation of ferromagnetic and antiferromagnetic moments in ultrathin La 0.7 Sr 0.3 MnO 3 layers embedded in antiferromagnetic Sr MnO 3 as they undergo a metal-to-insulator transition with decreasing thickness. Our results evince the role of orbital occupation, metallicity, and competition of different magnetic phases, in absence of spurious effects occurring in thin films as a result of symmetry breaking at La 0.7 Sr 0.3 MnO 3 interfaces and of incorporation of oxygen vacancies.	Aug 2021
I13-2-Diamond Manchester Imaging	Mechanisms of gas and shrinkage porosity formation in solidifying shear bands Shishira Bhagavath , Zhixuan Gong , Tim Wigger , Saurabh Shah , Bita Ghaffari , Mei Li , Shashidhara Marathe , Shyamprasad Karagadde , Peter D. Lee Journal Of Materials Processing Technology 26 DOI: 10.1016/j.jmatprotec.2021.117338 Diamond Proposal Number(s): [22053] Show Abstract ▼ Abstract: In specialised solidification processing techniques such as High Pressure Die Casting, Twin-Roll Casting and others, an additional external deformation load is applied to achieve the required shape, leading to the formation of microstructural features such as shear bands. The mechanism for forming these features is believed to be dependent on dynamically evolving strain fields, which are dependent on the local solid fraction, applied strain rates and casting geometry. To investigate this, a semisolid ( 50 % solid fraction) Al-10 wt.% Cu alloy is isothermally injected into a bespoke die using a custom-designed thermo-mechanical rig. The semisolid deformation, formation of Cu-rich dilatant bands and subsequent pore nucleation and growth are captured using fast synchrotron X-ray radiography. The local normal and shear strains acting on the mush are quantified using Digital image correlation to identify the dilatant shear bands and the dominant local strain component. Correlating the radiographs with strain maps reveals that gas pores within the dilated interstices grow, while those in compressed regions are squeezed out. A linear correlation between accumulated volumetric strain and porosity volume fraction demonstrates that higher dilations give rise to a local increase in both gas and shrinkage porosity.	Aug 2021

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