E02-JEM ARM 300CF
I11-High Resolution Powder Diffraction
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Eu-Pin
Tien
,
Guanhai
Cao
,
Yinlin
Chen
,
Nick
Clark
,
Evan
Tillotson
,
Duc-The
Ngo
,
Joseph H.
Carter
,
Stephen P.
Thompson
,
Chiu C.
Tang
,
Christopher
Allen
,
Sihai
Yang
,
Martin
Schroeder
,
Sarah J.
Haigh
Diamond Proposal Number(s):
[29225, 30737]
Open Access
Abstract: This work reports the thermal and electron beam stabilities of a series of isostructural metal-organic frameworks (MOFs) of type MFM-300(M), where M = Al, Ga, In, or Cr. MFM-300(Cr) was most electron beam stable, having an unusually high critical electron fluence of 1111 e-·Å-2 while the Group 13 element MOFs were found to be less stable. Within Group 13, MFM-300(Al) had the highest critical electron fluence of 330 e-·Å-2, compared to 189 e-·Å-2 and 147 e-·Å-2 for the Ga and In MOFs respectively. For all four MOFs, electron beam-induced structural degradation was independent of crystal size and was highly anisotropic, with the one-dimensional pore channels being the most stable, although the length and width of the channels decreased during electron beam irradiation. Notably, MFM-300(Cr) was found to retain crystallinity while shrinking up to 10%. Thermal stability was studied using in situ synchrotron X-ray diffraction at elevated temperature which revealed critical temperatures for crystal degradation to be 605, 570, 490 and 480°C for Al, Cr, Ga, and In, respectively. The pore channel diameters contracted by ~0.5% on desorption of solvent species but thermal degradation at higher temperatures was isotropic. The observed electron stabilities were found to scale with the relative inertness of the cations and correlate well to the measured lifetime of the materials when used as photocatalysts.
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Jul 2024
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I11-High Resolution Powder Diffraction
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Claire A.
Murray
,
Project M
Scientists
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Laura
Holland
,
Rebecca
O'Brien
,
Alice
Richards
,
Annabelle
Baker
,
Mark
Basham
,
David
Bond
,
Leigh D.
Connor
,
Sarah J.
Day
,
Jacob
Filik
,
Stuart
Fisher
,
Peter
Holloway
,
Karl
Levik
,
Ronaldo
Mercado
,
Jonathan
Potter
,
Chiu C.
Tang
,
Stephen P.
Thompson
,
Julia E.
Parker
Diamond Proposal Number(s):
[15723]
Open Access
Abstract: Calcite and vaterite crystallisation is strongly influenced by the presence of additives during the reaction process, as demonstrated by organic molecules in biogenic calcium carbonate formation. The effect of additives on the lattice parameters of calcite and vaterite in syntheses are frequently reported, but only as discrete studies discussing a single polymorph. The intertwined nature of these polymorphs, due to their shared reaction pathway, is rarely discussed. In this work we report the results of a large scale citizen science project to explore the influence of amino acids and related additives on both polymorphs, highlighting their differences and commonalities in terms of the effect on the lattice parameters and polymorph selectivity.
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Jan 2024
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I11-High Resolution Powder Diffraction
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Elisabetta
Nocerino
,
Shintaro
Kobayashi
,
Catherine
Witteveen
,
Ola K.
Forslund
,
Nami
Matsubara
,
Chiu
Tang
,
Takeshi
Matsukawa
,
Akinori
Hoshikawa
,
Akihiro
Koda
,
Kazuyoshi
Yoshimura
,
Izumi
Umegaki
,
Yasmine
Sassa
,
Fabian O.
Von Rohr
,
Vladimir
Pomjakushin
,
Jess H.
Brewer
,
Jun
Sugiyama
,
Martin
Mansson
Diamond Proposal Number(s):
[23840]
Open Access
Abstract: LiCrSe2 constitutes a recent valuable addition to the ensemble of two-dimensional triangular lattice antiferromagnets. In this work, we present a comprehensive study of the low temperature nuclear and magnetic structure established in this material. Being subject to a strong magnetoelastic coupling, LiCrSe2 was found to undergo a first order structural transition from a trigonal crystal system (P3¯m1
) to a monoclinic one (C2/m) at Ts = 30 K. Such restructuring of the lattice is accompanied by a magnetic transition at TN = 30 K. Refinement of the magnetic structure with neutron diffraction data and complementary muon spin rotation analysis reveal the presence of a complex incommensurate magnetic structure with a up-up-down-down arrangement of the chromium moments with ferromagnetic double chains coupled antiferromagnetically. The spin axial vector is also modulated both in direction and modulus, resulting in a spin density wave-like order with periodic suppression of the chromium moment along the chains. This behavior is believed to appear as a result of strong competition between direct exchange antiferromagnetic and superexchange ferromagnetic couplings established between both nearest neighbor and next nearest neighbor Cr3+ ions. We finally conjecture that the resulting magnetic order is stabilized via subtle vacancy/charge order within the lithium layers, potentially causing a mix of two co-existing magnetic phases within the sample.
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Oct 2023
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I11-High Resolution Powder Diffraction
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Abstract: Tracking the evolution of electrocatalysts over oxide-derived Cu materials during the electrochemical CO2 reduction reaction (eCO2RR) is pivotal for optimizing the product selectivity toward desired multi-carbon (C2+) products. However, the identification of the true intermediate active catalyst is still unclear. Here, we adopted a multi-modal characterization approach, primarily based on operando powder X-ray diffraction and operando micro-Raman spectroscopy, to study three Cu2O precursors with different morphologies, namely, octahedral (O-), cubic (C-), and nanowire (N-Cu2O). This multi-modal approach allows us to investigate the Cu2O nano-crystallites from the interface to the bulk structure. The results suggested notably different electrochemical reduction kinetics. 26.1% O-Cu2O and 90.6% C-Cu2O were reduced to much smaller Cu(0) domains after two hours of time-on-stream; N-Cu2O, with notably higher surface-to-volume ratio, was completely reduced within 45 minutes of time-on-stream. We accordingly observed a structure-reactivity correlation where a more intricate Cu2O/Cu grain network (and hence Cu+-Cu0 junctions) as observed in O-Cu2O, can lead to stable and quantitative production of ethylene at the Faradic efficiency of around 40% (in stark contrast to those of C- and N-Cu2O). The synergy between the Cu2O and Cu phases was also verified by density functional theory calculations. The upshifted d-band center of Cu2O/Cu in O-Cu2O is the most conducive toward the production of ethylene, whereas the downshifted d-band center of Cu2O/Cu in C-Cu2O leads to a decreased production of ethylene in the expense of unwanted production of hydrogen. We envisage that system optimization and design of new catalysts will become more facile and efficient using a related multi-modal operando characterization philosophy.
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Sep 2023
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Qi
Xue
,
Ching Kit Tommy
Wun
,
Tianxiang
Chen
,
Shogo
Kawaguchi
,
Sarah
Day
,
Chiu C.
Tang
,
Tai-Sing
Wu
,
Yun-Liang
Soo
,
Cong
Lin
,
Yung-Kang
Peng
,
Jun
Yin
,
Tsz Woon Benedict
Lo
Abstract: Supported bimetallic dual-atom catalysts (DACs) have been regarded as a promising class of materials for small molecule activation, but their syntheses remain challenging. Here, we report the controlled synthesis of supported Cu,Fe DACs on the ZrO6O4 secondary building units of UiO-66-NH2 which allows the efficient activation of O2. Remarkably high product selectivity (>92%) towards benzaldehyde over our model photocatalytic styrene oxidation reaction has been achieved. The superior reactivity has been attributed to the well-balanced synergy between the electronic and steric characteristics, which enables efficient O2 activation by the sterically restrained Cu and Fe sites in proximity for the formation of the bridging peroxy group. This bridging peroxy group facilitates the selective oxidation of styrene akin to many peroxide-based oxidants. The confined microporous environment allows the control of the electronic and geometric properties of the DACs, which subsequently sheds light towards more precise atomistic engineering that approaches the conventional inorganic metal(s)-complex counterparts.
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May 2023
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I11-High Resolution Powder Diffraction
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Bixian
Ying
,
Jack R.
Fitzpatrick
,
Zhenjie
Teng
,
Tianxiang
Chen
,
Tsz Woon Benedict
Lo
,
Vassilios
Siozios
,
Claire A.
Murray
,
Helen E. A.
Brand
,
Sarah
Day
,
Chiu C.
Tang
,
Robert S.
Weatherup
,
Peter
Nagel
,
Stefan
Schuppler
,
Martin
Winter
,
Karin
Kleiner
,
Michael
Merz
Diamond Proposal Number(s):
[19772]
Open Access
Abstract: The syntheses of Ni-poor (NCM111, LiNi1/3Co1/3Mn1/3O2) and Ni-rich (NCM811 LiNi0.8Co0.1Mn0.1O2) lithium transition-metal oxides (space group R3̅m) from hydroxide precursors (Ni1/3Co1/3Mn1/3(OH)2, Ni0.8Co0.1Mn0.1(OH)2) are investigated using in situ synchrotron powder diffraction and near-edge X-ray absorption fine structure spectroscopy. The development of the layered structure of these two cathode materials proceeds via two utterly different reaction mechanisms. While the synthesis of NCM811 involves a rock salt-type intermediate phase, NCM111 reveals a layered structure throughout the entire synthesis. Moreover, the necessity and the impact of a preannealing step and a high-temperature holding step are discussed.
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Jan 2023
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[24092]
Open Access
Abstract: Marine archaeological artefacts contain unexpected compounds due to prolonged exposure to the sea. These can remain dormant and embedded within materials until a change in their surrounding environment, such as exposure to oxygen, prompts a transformation. These changes can pose a problem, as acidic compounds are formed which disintegrate the material, or crystals form which physically break the artefact apart. The extent of these transformations is highly heterogeneous due to its dependence on the ability for oxygen to reach and catalyse these reactions. Additionally, these transformations are heavily dependent on the environment the artefact is exposed to, and the pathways available for ingress, either naturally or through previous degradation. This results in materials with a range of different compounds which are often co-located on the macro, micro and nano-scale. Trying to de-convolute these compounds is challenging, and usually requires a suite of complementary techniques to achieve. Here we report on damaging salts found within marine archaeological bricks and show how it is only possible to qualitatively and quantitatively understand what is present by employing a range of analytical techniques, such as XRD, SEM-EDS and SR-XPD. The marine archaeological bricks studied were found to contain a range of different sulfate-based salts, which had grown crystals in preferred orientations. This provides information which will guide further conservation strategies such as how these bricks are stored, conserved and protected in the future.
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May 2022
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I11-High Resolution Powder Diffraction
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Open Access
Abstract: Zeolites have found tremendous applications in the chemical industry. However, it is unclear about the dynamic nature of their active sites under the flow of adsorbate molecules for adsorption and catalysis, especially in operando conditions, which could be different from the as-synthesized structures. In the present study, we report a structural transformation of the adsorptive active sites in SAPO-34 zeolite by using acetone as a probe molecule under various temperatures. The combination of solid-state nuclear magnetic resonance, in-situ variable-temperature synchrotron x-ray diffraction, and in-situ diffuse-reflectance infrared Fourier-transform spectroscopy allow a clear identification and quantification that the chemisorption of acetone can convert the classical Brønsted acid site adsorption mode to an induced Frustrated Lewis Pairs adsorption mode at increasing temperatures. Such facile conversion is also supported by the calculations of ab-initio molecular-dynamics simulations. This work sheds new light on the importance of the dynamic structural alteration of active sites in zeolites with adsorbates at elevated temperatures.
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Apr 2022
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I11-High Resolution Powder Diffraction
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Tianxiang
Chen
,
Yong
Wang
,
Qi
Xue
,
Ching Kit Tommy
Wun
,
Pui Kin
So
,
Ka Fu
Yung
,
Tai-Sing
Wu
,
Yun-Liang
Soo
,
Keita
Taniya
,
Sarah
Day
,
Chiu C.
Tang
,
Zehao
Li
,
Bolong
Huang
,
Shik Chi Edman
Tsang
,
Kwok-Yin
Wong
,
Tsz Woon Benedict
Lo
Diamond Proposal Number(s):
[26404]
Open Access
Abstract: The large-scale synthesis of supported multinuclear catalysts with controllable metal nuclearity and constituent composition remains a formidable challenge. We report the stepwise assembly of supported atom-precise bimetallic ligand-mediated metal ensembles (LMMEs) by exploiting the underlying principles of coordination chemistry and solid-state chemistry. Lewis di-basic 2-methylimidazole is used to bridge multiple Cu2+ and M2+ (M = Co, Ni, Cu, and Zn) ions within ZSM-5 zeolites. We observe the metal constituent composition of the LMMEs by mass spectroscopy. The adjacent metal nuclei in the LMMEs offer substantial synergistic effects that enhance the catalytic performance by at least an order of magnitude in the model catalytic “click” reaction. It is envisaged that this stepwise assembly approach to develop supported multinuclear catalysts with atom precision could effectively bridge homogeneous and heterogeneous catalysis.
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Apr 2022
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
I11-High Resolution Powder Diffraction
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Abstract: Barium zirconate perovskites have been systematically investigated as protonic supports for ruthenium nanoparticles in the Haber–Bosch ammonia synthesis reaction. A series of supports based on barium zirconate were synthesized, for which the B-site of the ABO3 perovskite was doped with different aliovalent acceptor cations and in varying ratios, resulting in varying proton conductivities and trapping behaviors. Crucially, we provide direct evidence of the importance of a hydrogen-migration mechanism for ammonia synthesis over these proton-conducting materials from the studies of reaction kinetics, in situ X-ray photoelectron spectroscopy, and neutron powder diffraction (NPD), which requires the proper balance of oxygen vacancy concentration (B-site doping), trapping-site concentration, and proton-hopping activation energy. We report evidence of a large dynamic coverage of OH groups on the support and the first visualization of both weak and strong proton trap sites within the perovskite lattice through the use of NPD.
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Oct 2021
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