Search Results

You searched for all publications:

with publication states 'Published (Approved)'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

39 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	In-situ probing of the thermal treatment of h-BN towards exfoliation Zhengyu Yan , Amor Abdelkader , Sarah Day , Chiu Tang , Cinzia Casiraghi , Wajira Mirihanage Nanotechnology DOI: 10.1088/1361-6528/abce2e Diamond Proposal Number(s): [14099] Open Access Show Abstract ▼ Abstract: Two-dimensional (2D) hexagonal boron nitride (h-BN) is becoming increasingly interesting for wider engineering applications. Thermal exfoliation is being suggested as a facile technology to produce large quantities of 2D h-BN. Further optimization of the process requires fundamental understanding of the exfoliation mechanism, which is hardly realized by ex-situ techniques. In this study, time resolved in-situ synchrotron X-ray powder diffraction experiments are conducted while heat treating bulk h-BN up to 1273 K. During the heating process, linear expansion of c-axis is observed and the contraction of a-axis up to around 750 K is consistent with previous research. However, a changing behavior from contraction to expansion in a- axis direction is newly observed when heating over 750 K. With the consideration of previous thermally oxidation studies, a hypothesis of thermal assisted exfoliation with oxygen interstitial and substitution of nitrogen at high temperature is proposed.	Nov 2020
I11-High Resolution Powder Diffraction	A rational study on the geometric and electronic properties of single-atom catalysts for enhanced catalytic performance Qi Xue , Yi Xie , Simson Wu , Tai-sing Wu , Yun-liang Soo , Sarah Day , Chiu C. Tang , Ho W. Man , Sha T. Yuen , Kwok-yin Wong , Yin Wang , Benedict T. W. Lo , Shik C. E. Tsang Nanoscale 4 DOI: 10.1039/D0NR06006B Diamond Proposal Number(s): [23230] Show Abstract ▼ Abstract: We investigate the geometric and electronic properties of single-atom catalysts (SACs) within metal–organic frameworks (MOFs) with respect to electrocatalytic CO2 reduction as a model reaction. A series of mid-to-late 3d transition metals have been immobilised within the microporous cavity of UiO-66-NH2. By employing Rietveld refinement of new-generation synchrotron diffraction, we not only identified the crystallographic and atomic parameters of the SACs that are stabilised with a robust M⋯N(MOF) bonding of ca. 2.0 Å, but also elucidated the end-on coordination geometry with CO2. A volcano trend in the FEs of CO has been observed. In particular, the confinement effect within the rigid MOF can greatly facilitate redox hopping between the Cu SACs, rendering high FEs of CH4 and C2H4 at a current density of −100 mA cm−2. Although only demonstrated in selected SACs within UiO-66-NH2, this study sheds light on the rational engineering of molecular interactions(s) with SACs for the sustainable provision of fine chemicals.	Oct 2020
I11-High Resolution Powder Diffraction	Cooperative catalytically active sites for methanol activation by single metal ion-doped H-ZSM-5 Wei-che Lin , Simson Wu , Guangchao Li , Ping-luen Ho , Yichen Ye , Pu Zhao , Sarah Day , Chiu Tang , Wei Chen , Anmin Zheng , Benedict T. W. Lo , Shik Chi Edman Tsang Chemical Science 3 DOI: 10.1039/D0SC04058D Diamond Proposal Number(s): [16358] Open Access Show Abstract ▼ Abstract: Catalytic conversion of methanol to aromatics and hydrocarbons is regarded as a key alternative technology to oil processing. Although the inclusion of foreign metal species in H-ZSM-5 containing Brønsted acid site (BAS) is commonly found to enhance product yields, the nature of catalytically active sites and the rationalization for catalytic performance still remain obscure. Herein, by acquiring comparable structural parameters by both X-ray and neutron powder diffractions over a number of metal-modified ZSM-5 zeolites, it is demonstrated for the first time that active pairs of metal site-BAS within molecular distance is created when single and isolated transition metal cation is ion-exchanged with the zeolites. According to our DFT model, this could lead to the initial heterolytic cleavage of small molecules such as water and methanol by the pair with subsequent reactions to form products at high selectivity as that observed experimentally. It may account for their active and selective catalytic routes of small molecule activations.	Oct 2020
I11-High Resolution Powder Diffraction	Long-term stability of MFM-300(Al) towards toxic air pollutants Joseph H. Carter , Christopher Morris , Harry G. W. Godfrey , Sarah J. Day , Jonathan Potter , Stephen P. Thompson , Chiu C. Tang , Sihai Yang , Martin Schroeder Acs Applied Materials & Interfaces DOI: 10.1021/acsami.0c11134 Diamond Proposal Number(s): [14555] Open Access Show Abstract ▼ Abstract: Temperature or pressure-swing sorption in porous metal-organic framework (MOF) materials has been proposed for new gas separation technologies. The high tuneability of MOFs toward particular adsorbates and the relatively low energy penalty for system regeneration means that reversible physisorption in MOFs has the potential to create economic and environmental benefits compared with state-of-the-art chemisorption systems. However, for MOF-based sorbents to be commercialised they have to show long-term stability under the conditions imposed by the application. Here, we demonstrate the structural stability of MFM-300(Al) to the presence of a series of industrially-relevant toxic and corrosive gases, including SO2, NO2 and NH3, over four years using long duration synchrotron X-ray powder diffraction. Full structural analysis of gas-loaded MFM-300(Al) confirms the retention of these toxic gas molecules within the porous framework for up to 200 weeks, and cycling adsorption experiments verified the reusability of MFM-300(Al) for the capture of these toxic air pollutants.	Aug 2020
I11-High Resolution Powder Diffraction	Bulk fatigue induced by surface reconstruction in layered Ni-rich cathodes for Li-ion batteries Chao Xu , Katharina Märker , Juhan Lee , Amoghavarsha Mahadevegowda , Philip J. Reeves , Sarah J. Day , Matthias F. Groh , Steffen P. Emge , Caterina Ducati , B. Layla Mehdi , Chiu C. Tang , Clare P. Grey Nature Materials 414 DOI: 10.1038/s41563-020-0767-8 Diamond Proposal Number(s): [16733, 25186] Show Abstract ▼ Abstract: Ni-rich layered cathode materials are among the most promising candidates for high-energy-density Li-ion batteries, yet their degradation mechanisms are still poorly understood. We report a structure-driven degradation mechanism for NMC811 (LiNi0.8Mn0.1Co0.1O2), in which a proportion of the material exhibits a lowered accessible state of charge at the end of charging after repetitive cycling and becomes fatigued. Operando synchrotron long-duration X-ray diffraction enabled by a laser-thinned coin cell shows the emergence and growth in the concentration of this fatigued phase with cycle number. This degradation is structure driven and is not solely due to kinetic limitations or intergranular cracking: no bulk phase transformations, no increase in Li/Ni antisite mixing and no notable changes in the local structure or Li-ion mobility of the bulk are seen in aged NMCs. Instead, we propose that this degradation stems from the high interfacial lattice strain between the reconstructed surface and the bulk layered structure that develops when the latter is at states of charge above a distinct threshold of approximately 75%. This mechanism is expected to be universal in Ni-rich layered cathodes. Our findings provide fundamental insights into strategies to help mitigate this degradation process.	Aug 2020
I11-High Resolution Powder Diffraction	Evaluation of microflow configurations for scale inhibition and serial X-ray diffraction analysis of crystallization processes Mark A. Levenstein , Yi-yeoun Kim , Liam Hunter , Clara Anduix-canto , Carlos Gonzalez Nino , Sarah J. Day , Shunbo Li , William J. Marchant , Phillip A. Lee , Chiu C. Tang , Manfred Burghammer , Fiona C. Meldrum , Nikil Kapur Lab On A Chip 57 DOI: 10.1039/D0LC00239A Diamond Proposal Number(s): [10425, 12352] Open Access Show Abstract ▼ Abstract: The clean and reproducible conditions provided by microfluidic devices are ideal sample environments for in situ analyses of chemical and biochemical reactions and assembly processes. However, the small size of microchannels makes investigating the crystallization of poorly soluble materials on-chip challenging due to crystal nucleation and growth that result in channel fouling and blockage. Here, we demonstrate a reusable insert-based microfluidic platform for serial X-ray diffraction analysis and examine scale formation in response to continuous and segmented flow configurations across a range of temperatures. Under continuous flow, scale formation on the reactor walls begins almost immediately on mixing of the crystallizing species, which over time results in occlusion of the channel. Depletion of ions at the start of the channel results in reduced crystallization towards the end of the channel. Conversely, segmented flow can control crystallization, so it occurs entirely within the droplet. Consequently, the spatial location within the channel represents a temporal point in the crystallization process. Whilst each method can provide useful crystallographic information, time-resolved information is lost when reactor fouling occurs and changes the solution conditions with time. The flow within a single device can be manipulated to give a broad range of information addressing surface interaction or solution crystallization.	Jul 2020
I11-High Resolution Powder Diffraction	The effect of nano-twins on the thermoelectric properties of Ga2O3(ZnO)m (m = 9, 11, 13 and 15) homologous compounds D. T. Alvarez-ruiz , F. Azough , Thomas Slater , Sarah J. Day , R. Freer Journal Of The European Ceramic Society DOI: 10.1016/j.jeurceramsoc.2020.07.021 Show Abstract ▼ Abstract: Ga2O3(ZnO)m (m = integer) homologous compounds are naturally occurring nanostructured materials. Their intrinsically low thermal conductivity makes them attractive for thermoelectric applications. High density Ga2O3(ZnO)m (m = 9, 11, 13, and 15) single phase ceramics were prepared by solid-state reaction. Nano-sized, twin-like V-shaped boundaries parallel to b-axis (apex angle ∼ 60°) were observed for all compositions. Atomic resolution Z-contrast imaging and EDS analysis for m = 15 showed segregation of Ga ions at the interface of V-shaped twin boundaries. Thermal and charge transport properties depend on the value of m. Compositions with m = 9 exhibited very low lattice thermal conductivity of 2 to 1.5 W/m.K at 300 K to 900 K; compositions with m=15 showed improved power factor of 140 µW/m. K2 at 900 K leading to a thermoelectric figure of merit (ZT value) of 0.055. This study explores the structural variants and routes to improve the thermoelectric properties of these materials.	Jul 2020
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

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User