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154 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
B18-Core EXAFS I11-High Resolution Powder Diffraction	Anion redox as a means to derive layered manganese oxychalcogenides with exotic intergrowth structures Shunsuke Sasaki , Souvik Giri , Simon J. Cassidy , Sunita Dey , Maria Batuk , Daphne Vandemeulebroucke , Giannantonio Cibin , Ronald I. Smith , Philip Holdship , Clare P. Grey , Joke Hadermann , Simon J. Clarke Nature Communications 14 DOI: 10.1038/s41467-023-38489-3 Diamond Proposal Number(s): [25166, 14239] Open Access Show Abstract ▼ Abstract: Topochemistry enables step-by-step conversions of solid-state materials often leading to metastable structures that retain initial structural motifs. Recent advances in this field revealed many examples where relatively bulky anionic constituents were actively involved in redox reactions during (de)intercalation processes. Such reactions are often accompanied by anion-anion bond formation, which heralds possibilities to design novel structure types disparate from known precursors, in a controlled manner. Here we present the multistep conversion of layered oxychalcogenides Sr2MnO2Cu1.5Ch2 (Ch = S, Se) into Cu-deintercalated phases where antifluorite type [Cu1.5Ch2]2.5- slabs collapsed into two-dimensional arrays of chalcogen dimers. The collapse of the chalcogenide layers on deintercalation led to various stacking types of Sr2MnO2Ch2 slabs, which formed polychalcogenide structures unattainable by conventional high-temperature syntheses. Anion-redox topochemistry is demonstrated to be of interest not only for electrochemical applications but also as a means to design complex layered architectures.	May 2023
B18-Core EXAFS	High sodium-ion battery capacity in sulfur-deficient tin(II) sulfide thin films with a microrod morphology Zening Zhu , Geoffrey Hyett , Gillian Reid , Fred Robinson , Giannantonio Cibin , Andrew L. Hector Small Structures 7 DOI: 10.1002/sstr.202200396 Diamond Proposal Number(s): [14239] Open Access Show Abstract ▼ Abstract: Sulfur-deficient SnS thin films for sodium-ion battery anode application are prepared using aerosol-assisted chemical vapor deposition. Growth directly onto the metal foil current collector forms sulfur-deficient SnS microrod structures via a vapor–liquid–solid growth mechanism, with 92 nm average SnS crystallite size and an 800 nm film thickness. The sulfur deficiency is demonstrated with energy-dispersive X-ray analysis, powder X-ray diffraction, and X-ray absorption near-edge structure analyses. This sulfur-deficient SnS material demonstrates a very high capacity in sodium half cells. The first reduction scan at a specific current of 150 mA g−1 shows a capacity of 1084 mAh g−1. At the 50th cycle the specific capacity is 638 mAh g−1 for reduction and 593 mAh g−1 for oxidation. This capacity is demonstrated for tin sulfide itself without the need for a nanostructured carbon support, unlike previous high capacity SnS anodes in the literature. Both the capacity and ex situ characterization experiments indicate a conversion reaction producing tin, followed by alloying with sodium during reduction, and that both of these processes are reversible during oxidation.	Feb 2023
B18-Core EXAFS	Spectroscopic (XAS, FTIR) investigations into arsenic adsorption onto TiO2/Fe2O3 composites: Evaluation of the surface complexes, speciation and precipitation predicted by modelling Jay C. Bullen , Chaipat Lapinee , Laura A. Miller , Florence Bullough , Andrew J. Berry , Jens Najorka , Giannantonio Cibin , Ramon Vilar , Dominik J. Weiss Results In Surfaces And Interfaces 64 DOI: 10.1016/j.rsurfi.2022.100084 Diamond Proposal Number(s): [11226] Open Access Show Abstract ▼ Abstract: Over 50 million people in South Asia are exposed to groundwater contaminated with carcinogenic arsenic(III). Photocatalyst-adsorbent composite materials are popularly developed for removing arsenic in a single-step water treatment. Here, As(III) is oxidised to As(V), which is subsequently removed via adsorption. We previously developed a component additive surface complexation model (CA-SCM) to predict the speciation of arsenic adsorbed onto TiO 2/Fe2O3 under different environmental conditions, using surface complexes taken from studies of single-phase minerals. In this work, we critically evaluate this approach, using experimental observations of the surface structures of arsenic adsorbed onto TiO 2/Fe2O3. Extended X-ray absorption fine structure spectroscopy (EXAFS) indicates significant As(III) surface precipitation, and the possible formation of tridentate 3C complexes. EXAFS was unable to identify As binding modes for TiO 2 and Fe2O3 surface complexes simultaneously, highlighting the challenge of analysing composite surfaces. FTIR and zeta potential analysis indicate that As(III)-Fe2O3 surface complexes are protonated at neutral pH, whilst As(III)-TiO 2, As(V)-Fe2O3 and As(V)-TiO 2 surface complexes are negatively charged. Our study confirms the speciation predicted by CA-SCM, particularly As(III) surface precipitation, but also introduces the possibility of tridentate As(III) at acidic pH. This study highlights how experiment and modelling can be combined to assess surface complexation on composite surfaces.	Sep 2022
B18-Core EXAFS I10-Beamline for Advanced Dichroism	Absence of spin-mixed states in ferrimagnet Yttrium iron garnet D. Cheshire , P. Bencok , D. Gianolio , G. Cibin , V. K. Lazarov , Gerrit Van Der Laan , S. A. Cavill Journal Of Applied Physics 132, 103902 DOI: 10.1063/5.0099477 Diamond Proposal Number(s): [24930, 22629] Open Access Show Abstract ▼ Abstract: The spectroscopic g-factor of epitaxial thin film Yttrium Iron Garnet (YIG) has been studied using a combination of ferromagnetic resonance spectroscopy and x-ray magnetic circular dichroism. The values obtained by the two techniques are found, within experimental error, to be in agreement using Kittel’s original derivation for the g-factor. For an insulating material with an entirely Fe3+ configuration, a spin mixing correction to Kittel’s derivation of the spectroscopic g-factor, as recently shown by Shaw et al. [Phys. Rev. Lett. 127, 207201 (2021)] for metallic systems, is not required and demonstrates that the spin mixing parameter is small in YIG due to negligible spin–orbit coupling.	Sep 2022
B18-Core EXAFS	Influence of the cation on the reaction mechanism of sodium uptake and release in bivalent transition metal thiophosphate anodes: a case study of Fe2P2S6 Jonas Van Dinter , Sylvio Indris , Martin Etter , Giannantonio Cibin , Wolfgang Bensch Zeitschrift Für Anorganische Und Allgemeine Chemie DOI: 10.1002/zaac.202200227 Diamond Proposal Number(s): [20060] Show Abstract ▼ Abstract: The layered active material Fe 2 P 2 S 6 was examined as anode material in sodium-ion batteries (SIBs) and compared to previously investigated Ni 2 P 2 S 6 . A reversible specific capacity of 540 mAh g ‑1 was achieved after 250 cycles, depicting similar electrochemical performance as observed for Ni 2 P 2 S 6 . The rate capability and long-term behavior of these two materials are also very similar. Another objective was to elucidate the reaction mechanism during discharging and charging by applying several techniques such as X-ray diffraction, pair distribution function analysis as well as X-ray absorption and solid state NMR spectroscopy. The results clearly demonstrate that the majority of Fe 2+ is reduced to elemental Fe during the uptake of 5 Na/f.u., while an amorphous intermediate is generated, which was identified as Na 4 P 2 S 6 by solid state NMR. Completely discharging against a Na metal counter electrode leads to the formation of nanocrystalline Na 2 S and indications of the formation of polymeric phosphorus were found. In sum, the Na uptake reaction process observed for Fe 2 P 2 S 6 coincides with the previously unraveled reaction pathway of Ni 2 P 2 S 6 . We therefore conclude that a universal reaction takes places for bivalent transition metal thiophosphate (M 2 P 2 S 6 ) electrodes in SIBs.	Sep 2022
B18-Core EXAFS	Conversion of glucose to fructose over Sn and Ga-doped zeolite Y in methanol and water media Mohamed M. M. Kashbor , Dedi Sutarma , James Railton , Naoko Sano , Peter J. Cumpson , Diego Gianolio , Giannantonio Cibin , Luke Forster , Carmine D’agostino , Xi Liu , Liwei Chen , Volkan Degirmenci , Marco Conte Applied Catalysis A: General 9 DOI: 10.1016/j.apcata.2022.118689 Diamond Proposal Number(s): [24728] Open Access Show Abstract ▼ Abstract: In this study, we use zeolite Y as a support for the synthesis of Sn and Ga doped zeolites aimed at the isomerization of glucose to fructose. Though these materials are inactive in water, they are active in methanol and we could ascertain a reaction pathway involving a hydride shift for the interconversion of glucose to fructose and mannose, and a Brønsted acid pathway with the formation of a methyl fructoside intermediate and its hydrolysis to fructose if water was added afterwards. By using characterizations comprising: chemisorption, XPS, XRD, HAADF-STEM and EXAFS; it was possible to demonstrate that a straightforward impregnation protocol for the preparation of our catalysts, led to Sn/Y mainly consisting of small SnO2 clusters on the external surface of the zeolite, whereas Ga/Y consisting of highly dispersed Ga species mostly inside the zeolite pores; and a catalytic activity that appears to be dominated by Brønsted acid sites.	May 2022
B18-Core EXAFS	Enhanced cycling stability in the anion redox material P3-type Zn-substituted sodium manganese oxide Stephanie F. Linnell , Moritz Hirsbrunner , Saki Imada , Giannantonio Cibin , Aaron B. Naden , Alan V. Chadwick , John T. S. Irvine , Laurent C. Duda , Anthony Robert Armstrong Chemelectrochem DOI: 10.1002/celc.202200240 Diamond Proposal Number(s): [14239] Open Access Show Abstract ▼ Abstract: Sodium layered oxides showing oxygen redox activity are promising positive electrodes for sodium‑ion batteries (SIBs). However, structural degradation typically results in limited reversibility of the oxygen redox activity. Herein, the effect of Zn‑doping on the electrochemical properties of P3-type sodium manganese oxide, synthesised under air and oxygen is investigated for the first time. Air‑Na 0.67 Mn 0.9 Zn 0.1 O 2 and Oxy‑Na 0.67 Mn 0.9 Zn 0.1 O 2 exhibit stable cycling performance between 1.8 and 3.8 V, each maintaining 96% of their initial capacity after 30 cycles, where Mn 3+ /Mn 4+ redox dominates. Increasing the voltage range to 1.8‑4.3 V activates oxygen redox. For the material synthesised under air, oxygen redox activity is based on Zn, with limited reversibility. The additional transition metal vacancies in the material synthesised under oxygen result in enhanced oxygen redox reversibility with small voltage hysteresis. These results may assist the development of high‑capacity and structurally stable oxygen redox‑based materials for SIBs.	Apr 2022
B18-Core EXAFS	Pyrolysis of a metal–organic framework followed by in situ X-ray absorption spectroscopy, powder diffraction and pair distribution function analysis Mads Folkjær , Lars F. Lundegaard , Henrik S. Jeppesen , Melissa J. Marks , Mathias S. Hvid , Sara Frank , Giannantonio Cibin , Nina Lock Dalton Transactions 371 DOI: 10.1039/D2DT00616B Diamond Proposal Number(s): [22410] Show Abstract ▼ Abstract: Metal–organic frameworks (MOFs) can serve as precursors for new nanomaterials via thermal decomposition. Such MOF-derived nanomaterials (MDNs) are often comprised of metal and/or metal oxide particles embedded on porous carbon. The morphology of MDNs is similar to that of the precursor MOF, and improved stability and catalytic properties have been demonstrated. However, the pathway from MOF to MDN is only well understood for a few systems, and in situ studies are needed to elucidate the full phase behaviour and time/temperature dependency. In this work, we follow the MOF-to-MDN transformation in situ by using three complementary techniques: X-ray absorption spectroscopy (XAS), powder X-ray diffraction (PXRD), and X-ray total scattering/pair distribution function (TS/PDF) analysis. The thermal decomposition of HKUST-1, i.e. the archetypical MOF Cu3(btc = 1,3,5-benzenetricarboxylate)2, is followed from room temperature to 500 °C by applying different heating ramps. Real space correlations are followed by PDF and extended X-ray absorption fine structure (EXAFS) analysis, and quantitative phase fractions are obtained by refinement of PXRD and PDF data, and by linear combination analysis (LCA) of X-ray absorption near edge Structure (XANES) data. We find that HKUST-1 decomposes at 300–325 °C into copper(I) oxide and metallic copper. Above 350–470 °C, metal particles remain as the only copper species. There is an overall good agreement between all three techniques with respect to the phase evolution, and the study paves the road towards rational synthesis of a Cu2O/Cu/carbon material with the desired metal/metal oxide composition. More importantly, our investigations serve as a benchmark study demonstrating that this methodology is generally applicable for studying the thermal decomposition of MOFs.	Apr 2022
B18-Core EXAFS	Interplay between structural, magnetic, and electronic states in the pyrochlore iridate Eu2Ir2O7 Manjil Das , Sayantika Bhowal , Jhuma Sannigrahi , Abhisek Bandyopadhyay , Anupam Banerjee , Giannantonio Cibin , Dmitry Khalyavin , Niladri Banerjee , Devashibhai Adroja , Indra Dasgupta , Subham Majumdar Physical Review B 105 DOI: 10.1103/PhysRevB.105.134421 Diamond Proposal Number(s): [17752] Show Abstract ▼ Abstract: We address the concomitant metal-insulator transition (MIT) and antiferromagnetic ordering in the novel pyrochlore iridate Eu 2 Ir 2 O 7 by combining x-ray absorption spectroscopy, x-ray and neutron diffractions, and density functional theory (DFT)-based calculations. The temperature dependent powder x-ray diffraction clearly rules out any change in the lattice symmetry below the MIT, nevertheless a clear anomaly in the Ir-O-Ir bond angle and Ir-O bond length is evident at the onset of MIT. From the x-ray absorption near edge structure (XANES) spectroscopic study of Ir- L 3 and L 2 edges, the effective spin-orbit coupling is found to be intermediate, at least quite far from the strong atomic spin-orbit coupling limit. Powder neutron diffraction measurement is in line with an all-in-all-out magnetic structure of the Ir-tetrahedra in this compound, which is quite common among rare-earth pyrochlore iridates. The sharp change in the Ir-O-Ir bond angle around the MIT possibly arises from the exchange striction mechanism, which favors an enhanced electron correlation via weakening of Ir-Ir orbital overlap and an insulating phase below T M I . The theoretical calculations indicate an insulating state for shorter bond angle validating the experimental observation. Our DFT calculations show a possibility of intriguing topological phase below a critical value of the Ir-O distance, which is shorter than the experimentally observed bond length. Therefore, a topological state may be realized in bulk Eu 2 Ir 2 O 7 sample if the Ir-O bond length can be reduced by the application of sufficient external pressure.	Apr 2022
B18-Core EXAFS	Multiple emerging nano-phases are at the origin of the low lattice thermal conductivity of SnSe? Wei Xu , Peng-Peng Shang , Augusto Marcelli , Giannantonio Cibin , Jing-Feng Li Materials Today Physics 120 DOI: 10.1016/j.mtphys.2022.100656 Diamond Proposal Number(s): [21906] Show Abstract ▼ Abstract: Thermoelectrics are well recognized materials for energy harvesting and many solid-state cooling devices are already present on the market. SnSe is an inexpensive binary system made by earth-abundant elements that holds the record-high performance among the semiconductor materials although the origin of its ultralow thermal conductivity is still not understood. Both X-ray and neutron diffraction experiments identified in SnSe at high temperature a transition from the α-phase (Pnma) to the β-phase (Cmcm). In this contribution using for the first time in-situ temperature-dependent X-ray Absorption Fine structure spectroscopy (T-XAFS) at Sn and Se K-edge, we showed the occurrence in the XAS data of two isosbestic points, which support the coexistence of two phases in a wide temperature range. Moreover, in the SnSe matrix Sn-O bonds are continuously formed and SnO2, SeO2 and SnSe2 nanophases are emerging at high temperature. The experiment points out how these local nanophases are formed above 600 K. These emerging nano-phases affect the mean free path of phonons reducing the lattice thermal conductivity and, together with the crystal structural phase transition, may account for the low thermal conductivity measured in SnSe single crystals.	Mar 2022

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