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32 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I11-High Resolution Powder Diffraction	Dynamic crystallization pathways of polymorphic pharmaceuticals revealed in segmented flow with inline powder XRD Mark A. Levenstein , Lois E. Wayment , C. Daniel Scott , Ruth A. Lunt , Pierre-baptiste Flandrin , Sarah Day , Chiu Tang , Chick C. Wilson , Fiona C. Meldrum , Nikil Kapur , Karen Robertson Analytical Chemistry DOI: 10.1021/acs.analchem.0c00860 Diamond Proposal Number(s): [14807, 18771, 18405] Show Abstract ▼ Abstract: Understanding the transitions between polymorphs is essential in the development of strategies for manufacturing and max-imizing the efficiency of pharmaceuticals. However, this can be extremely challenging: crystallization can be influenced by subtle changes in environment such as temperature and mixing intensity or even imperfections in the crystallizer walls. Here, we highlight the importance of in situ measurements in understanding crystallization mechanisms, where a segmented flow crystallizer was used to study the crystallization of the pharmaceuticals urea:barbituric acid (UBA) and carbamazepine (CBZ). The reactor provides highly reproducible reaction conditions, while in situ synchrotron powder X-ray diffraction (PXRD) enables us to monitor the evolution of this system. UBA has two polymorphs of almost equivalent free-energy and so is typically obtained as a polymorphic mixture. In situ PXRD uncovered a progression of polymorphs from UBA III to the thermodynamic polymorph UBA I, where different positions along the length of the tubular flow crystallizer correspond to different reaction times. Addition of UBA I seed crystals modified this pathway such that only UBA I was observed throughout, while transformation from UBA III into UBA I still occurred in the presence of UBA III seeds. Information re-garding the mixing-dependent kinetics of the CBZ form II to III transformation was also uncovered in a series of seeded and unseeded flow crystallization runs, despite atypical habit expression. These results illustrate the importance of coupling controlled reaction environments with in situ XRD to study the phase relationships in polymorphic materials.	May 2020
I11-High Resolution Powder Diffraction	Evaluation of Brønsted and Lewis acid sites in H-ZSM-5 and H-USY with or without metal modification using probe molecule-synchrotron X-ray powder diffraction Benedict T. W. Lo , Wei-che Lin , Molly Meng Jung Li , Sarah Day , Chiu Tang , Shik Chi Edman Tsang Applied Catalysis A: General 596 DOI: 10.1016/j.apcata.2020.117528 Show Abstract ▼ Abstract: The adsorbate interactions of furans as probe molecules in H-ZSM-5 and H-USY with and without metal ion modification have been revealed by synchrotron X-ray powder diffraction (SXRD). The Rietveld refinements give both qualitatively and quantitatively the spatial arrangements and adsorption geometries of furan and 2,5-dimethylfuran (DMF) on the Brønsted acid sites (BAS) and metal Lewis acid sites (LAS). The bonding information between the adsorbate-framework can also be correlated with thermogravimetric findings. The use of probe molecule-SXRD can be used as a new characterisation tool which can spatially interrogate the acidity of crystalline porous catalysts, leading to molecular engineering of new catalytic systems.	Apr 2020
I11-High Resolution Powder Diffraction	18-month hydration of a low-pH cement for geological disposal of radioactive waste: The Cebama reference cement Rita G. W. Vasconcelos , Brant Walkley , Sarah Day , Chiu C. Tang , Haris Paraskevoulakos , Laura J. Gardner , Claire L. Corkhill Applied Geochemistry DOI: 10.1016/j.apgeochem.2020.104536 Diamond Proposal Number(s): [10038] Open Access Show Abstract ▼ Abstract: Low-pH cements are candidate materials for use in the construction of geological disposal facilities for the long-term management of nuclear waste. Since these facilities will operate over long time scales, the changes in mineralogy and microstructure require evaluation as a function of time. As a first step towards this understanding, the hydration of a standardised low-pH cement paste, known as the Cebama reference cement, was investigated over an 18-month period. Characterisation was performed at 28 days of curing, at 20 °C and 40 °C, and novel synchrotron radiation X-ray diffraction experiments were performed, in-situ, from 90 min to 18 months of curing. Concurrent solid state 29Si and 27Al MAS NMR data were acquired for parallel samples to quantify the extent of cement hydration and the composition and mean chain length of the predominant calcium aluminosilicate hydrate (C-(A)-S-H) reaction product. After 18 months, cement clinker phases were still present, highlighting the slow hydration kinetics of this low-pH cement. The data presented provide a benchmark for ongoing and future studies of low-pH cements in geological disposal environments, over extended time scales.	Mar 2020
I11-High Resolution Powder Diffraction	Enantiospecificity in achiral zeolites for asymmetric catalysis Tianxiang Chen , Ching Kit Tommy Wun , Sarah J. Day , Chiu C. Tang , Tsz Woon Benedict Lo Physical Chemistry Chemical Physics 121 DOI: 10.1039/D0CP00262C Diamond Proposal Number(s): [23230] Show Abstract ▼ Abstract: This article highlights the recent fundamental study in using achiral and chiral porous materials for the potential applications in asymmetric catalysis. Thanks to the new-generation synchrotron X-ray powder diffraction (SXRD) facilities, we reveal the presence of the unique ‘chiral region’ in achiral zeolites with the MFI topology. Both the inherent site-isolation effect of the active sites and internal confinement restraints in zeolites are critical for creating ‘chiral regions’ that can aid the design of more enantioselective catalytic reactions. We also offer an outlook on the challenges and opportunities of this research area.	Feb 2020
I11-High Resolution Powder Diffraction	Differential adsorption of L- and D-lysine on achiral MFI zeolites as determined by synchrotron X-ray powder diffraction and thermogravimetric analysis Tianxiang Chen , Bolong Huang , Sarah Day , Chiu Chung Tang , Shik Chi Edman Tsang , Kwok-yin Wong , Tsz Woon Benedict Lo Angewandte Chemie International Edition DOI: 10.1002/anie.201909352 Diamond Proposal Number(s): [23230] Show Abstract ▼ Abstract: We report the first crystallographic observation of stereospecific bindings of L‐ and D‐lysine in achiral MFI zeolites. The MFI structure has offered inherent geometric and internal confinement effects for the enantiomeric difference in L‐ and D‐lysine adsorption. Notable difference over the sorption properties has been observed by circular dichroism (CD) spectroscopy and thermogravimetric analysis (TGA). Distinct L‐ and D‐lysine adsorption behaviours on the H‐ZSM‐5 framework have been revealed by the Rietveld refinement of high‐resolution synchrotron X‐ray powder diffraction (SXRD) data and the density functional theory (DFT) calculation. Despite only demonstrated in L‐ and D‐lysine over MFI zeolites, the differential adsorption study sheds light towards the rational engineering of molecular interactions(s) with achiral microporous materials for chiral separation purposes.	Nov 2019
I11-High Resolution Powder Diffraction	Capacity fading mechanisms of NCM-811 cathodes in lithium-ion batteries studied by X-ray diffraction and other diagnostics Franziska Friedrich , Benjamin Strehle , Anna Freiberg , Karin Kleiner , Sarah J. Day , Christoph Erk , Michele Piana , Hubert A. Gasteiger Journal Of The Electrochemical Society 166, A3760 - A3774 DOI: 10.1149/2.0821915jes Diamond Proposal Number(s): [16866] Open Access Show Abstract ▼ Abstract: Ni-rich layered oxides, like NCM-811, are promising lithium-ion battery cathode materials for applications such as electric vehicles. However, pronounced capacity fading, especially at high voltages, still lead to a limited cycle life, whereby the underlying degradation mechanisms, e.g. whether they are detrimental reactions in the bulk or at the surface, are still controversially discussed. Here, we investigate the capacity fading of NCM-811/graphite full-cells over 1000 cycles by a combination of in situ synchrotron X-ray powder diffraction, impedance spectroscopy, and X-ray photoelectron spectroscopy. In order to focus on the NCM-811 material, we excluded Li loss at the anode by pre-lithiating the graphite. We were able to find a quantitative correlation between NCM-811 lattice parameters and capacity fading. Our results prove that there are no considerable changes in the bulk structure, which could be responsible for the observed ≈20% capacity loss over the 1000 cycles. However, we identified the formation of a resistive surface layer, which is responsible for (i) an irreversible loss of capacity due to the material lost for its formation, and (ii) for a considerable impedance growth. Further evidence is provided that the surface layer is gradually formed around the primary NCM-811 particles.	Nov 2019
B22-Multimode InfraRed imaging And Microspectroscopy	Reversible coordinative binding and separation of sulfur dioxide in a robust metal–organic framework with open copper sites Gemma L. Smith , Jennifer E. Eyley , Xue Han , Xinran Zhang , Jiangnan Li , Nicholas M. Jacques , Harry G. W. Godfrey , Stephen P. Argent , Laura J. Mccormick Mcpherson , Simon J. Teat , Yongqiang Cheng , Mark D. Frogley , Gianfelice Cinque , Sarah Day , Chiu C. Tang , Timothy L. Easun , Svemir Rudic , Anibal J. Ramirez-cuesta , Sihai Yang , Martin Schroeder Nature Materials 29 DOI: 10.1038/s41563-019-0495-0 Show Abstract ▼ Abstract: Emissions of SO2 from flue gas and marine transport have detrimental impacts on the environment and human health, but SO2 is also an important industrial feedstock if it can be recovered, stored and transported efficiently. Here we report the exceptional adsorption and separation of SO2 in a porous material, [Cu2(L)] (H4L = 4′,4‴-(pyridine-3,5-diyl)bis([1,1′-biphenyl]-3,5-dicarboxylic acid)), MFM-170. MFM-170 exhibits fully reversible SO2 uptake of 17.5 mmol g−1 at 298 K and 1.0 bar, and the SO2 binding domains for trapped molecules within MFM-170 have been determined. We report the reversible coordination of SO2 to open Cu(ii) sites, which contributes to excellent adsorption thermodynamics and selectivities for SO2 binding and facile regeneration of MFM-170 after desorption. MFM-170 is stable to water, acid and base and shows great promise for the dynamic separation of SO2 from simulated flue gas mixtures, as confirmed by breakthrough experiments.	Oct 2019
I11-High Resolution Powder Diffraction	Fine control of Curie temperature of magnetocaloric alloys La(Fe,Co,Si)13 using electrolytic hydriding Liya Guo , Edmund Lovell , Qiwei Tang , David C. Boldrin , Chiu C. Tang , Sarah J. Day , Lesley F. Cohen , Mary P. Ryan Scripta Materialia 175, 33 - 37 DOI: 10.1016/j.scriptamat.2019.08.017 Diamond Proposal Number(s): [19792] Show Abstract ▼ Abstract: This work demonstrates precision control of hydrogen content in La(Fe,Co,Si)13Hδ for the development of environmentally friendly magnetocaloric-based cooling technologies, using an electrolytic hydriding technique. We show the Curie temperature, a critical parameter which directly governs the temperature window of effective cooling, can be varied easily and reproducibly in 1 K steps within the range 274 K to 402 K. Importantly, both partially (up to 10%) and fully hydrided compositions retain favorable entropy change values comparable to that of the base composition. Crucially, we show in these second-order phase transition compounds, partial hydriding is stable and not susceptible against phase separation.	Oct 2019
I11-High Resolution Powder Diffraction	Thermally-induced phase transformations in KNNS-BNKZ lead-free piezoceramics J. Tangsritrakul , C. C. Tang , Sarah Day , David Hall Journal Of The European Ceramic Society DOI: 10.1016/j.jeurceramsoc.2019.10.009 Diamond Proposal Number(s): [13116] Show Abstract ▼ Abstract: Promising piezoelectric properties have been reported in potassium sodium niobate-based ceramics by introducing Bi0.5(Na0.82K0.18)0.5ZrO3 (BNKZ) into K0.48Na0.52Nb0.95Sb0.05O3 (KNNS) solid solutions in order to control the polymorphic phase transformation temperatures. In the present study, synchrotron x-ray powder diffraction (SXPD) was employed in combination with dielectric and ferroelectric measurements in order to clarify the influence of BNKZ on the phase transition temperatures of (1-x)KNNS-(x)BNKZ ceramics (with x = 0 to 0.05). The results, presented in terms of temperature-dependent SXPD patterns, dielectric permittivity and thermal depolarisation characteristics, confirmed that polymorphic phase transformation temperatures all shifted in a systematic manner with increasing BNKZ content. Broadening of the phase transition regions was also observed with increasing BNKZ content, leading to improvements in thermal stability of the ferroelectric properties. Microstructural examination of the KNNS-BNKZ ceramics revealed the presence of core-shell microstructures; this was correlated with the presence of weak shoulders on the diffraction peaks.	Oct 2019
I11-High Resolution Powder Diffraction	The properties of methane clathrate in the presence of ammonium sulphate solutions with relevance to Titan Emmal Safi , Stephen P. Thompson , Aneurin Evans , Sarah J. Day , Claire A. Murray , Annabelle R. Baker , Joana M. Oliveira , Jaco Th. Van Loon EPSC-DPS Joint Meeting 2019 Show Abstract ▼ Abstract: The source of atmospheric methane on Saturn’s satellite Titan is currently unknown. However, one possibility is that it originates from clathrate hydrates formed below the surface. Titan’s sub-surface ocean is believed to be composed of saline, rather than pure, water and in situ experimental data on clathrate formation under these conditions are largely absent in literature. Here, synchrotron X-ray powder diﬀraction (SXRPD) is used to study the properties of methane clathrate hydrates formed in the presence of ammonium sulphate solutions under low temperature conditions with a pressure of 26 bar.	Sep 2019

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