I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[27557]
Abstract: Soluble additives are widely used to control crystallization processes, modifying the morphologies, sizes, polymorphs, and physical properties of the product crystals. Here, a simple and versatile strategy is shown to significantly enhance the potency of soluble additives, ranging from ions and amino acids to large dye molecules, enabling them to be effective even at low concentrations. Addition of small amounts of miscible organic co-solvents to an aqueous crystallization solution can yield enhanced morphological changes and an order of magnitude increase of additive incorporation within single crystals─a level that cannot be achieved in pure aqueous solutions at any additive concentration. The generality of this strategy is demonstrated by application to crystals of calcium carbonate, manganese carbonate, and strontium sulfate, with a more pronounced effect observed for co-solvents with lower dielectric constants and polarities, indicating a general underlying mechanism that alters water activity. This work increases the understanding of additive/crystal interactions and may see great application in industrial-scale crystal synthesis.
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Nov 2021
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I13-2-Diamond Manchester Imaging
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Clara
Anduix-Canto
,
Mark A.
Levenstein
,
Yi-Yeoun
Kim
,
Jose R. A.
Godinho
,
Alexander N.
Kulak
,
Carlos
Gonzalez Nino
,
Philip J.
Withers
,
Jonathan P.
Wright
,
Nikil
Kapur
,
Hugo K.
Christenson
,
Fiona C.
Meldrum
Diamond Proposal Number(s):
[13578, 17314]
Open Access
Abstract: Characterizing the pathways by which crystals form remains a significant challenge, particularly when multiple pathways operate simultaneously. Here, an imaging-based strategy is introduced that exploits confinement effects to track the evolution of a population of crystals in 3D and to characterize crystallization pathways. Focusing on calcium sulfate formation in aqueous solution at room temperature, precipitation is carried out within nanoporous media, which ensures that the crystals are fixed in position and develop slowly. The evolution of their size, shape, and polymorph can then be tracked in situ using synchrotron X-ray computed tomography and diffraction computed tomography without isolating and potentially altering the crystals. The study shows that bassanite (CaSO4 0.5H2O) forms via an amorphous precursor phase and that it exhibits long-term stability in these nanoscale pores. Further, the thermodynamically stable phase gypsum (CaSO4 2H2O) can precipitate by different pathways according to the local physical environment. Insight into crystallization in nanoconfinement is also gained, and the crystals are seen to grow throughout the nanoporous network without causing structural damage. This work therefore offers a novel strategy for studying crystallization pathways and demonstrates the significant impact of confinement on calcium sulfate precipitation, which is relevant to its formation in many real-world environments.
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Sep 2021
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B18-Core EXAFS
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Abstract: Joule heating studies on nanoparticle/nanocarbon hybrid aerogels have been reported, but systematic investigations on hydrotalcite-derived catalysts supported onto reduced graphene oxide (rGO) aerogels are rare. In this study, hydrotalcite-derived Cu-Al2O3 nanoparticles were incorporated into a porous and multifunctional rGO aerogel support for fabricating electrically conducting Cu-Al2O3/rGO hybrid aerogels, and their properties were investigated in detail. The hybridization of Cu-Al2O3 with a 3D nanocarbon support network imparts additional functionalities to the widely used functional inorganic nanoparticles, such as direct electrical framework heating and easy regeneration and separation of spent nanoparticles, with well-spaced nanoparticle segregation. 3D variable-range hopping model fitting confirmed that electrons were able to reach the entire aerogel to enable uniform resistive heating. The conductivity of the nanocarbon support framework facilitates uniform and fast heating (up to 636 K/min) of the embedded nanoparticles at very low energy consumption, while the large porosity and high thermal conductivity enable efficient heat dissipation during natural cooling (up to 336 K/min). The thermal stability of the hybrid aerogel was demonstrated by repeated heating/cooling cycling at different temperatures that were relevant to important industrial applications. The facile synthetic approach can be easily adapted to fabricate other types of multifunctional nanoparticle/nanocarbon hybrid aerogels, such as the MgAl-MMO/rGO aerogel and the Ni-Al2O3/rGO aerogel. These findings open up new routes to the functionalization of inorganic nanoparticles and extend their application ranges that involve electrical/thermal heating, temperature-dependent catalysis, sorption, and sensing.
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Jul 2021
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I11-High Resolution Powder Diffraction
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Yi-Yeoun
Kim
,
Robert
Darkins
,
Alexander
Broad
,
Alexander N.
Kulak
,
Mark A.
Holden
,
Ouassef
Nahi
,
Steven P.
Armes
,
Chiu C.
Tang
,
Rebecca F.
Thompson
,
Frederic
Marin
,
Dorothy M.
Duffy
,
Fiona C.
Meldrum
Open Access
Abstract: Acidic macromolecules are traditionally considered key to calcium carbonate biomineralisation and have long been first choice in the bio-inspired synthesis of crystalline materials. Here, we challenge this view and demonstrate that low-charge macromolecules can vastly outperform their acidic counterparts in the synthesis of nanocomposites. Using gold nanoparticles functionalised with low charge, hydroxyl-rich proteins and homopolymers as growth additives, we show that extremely high concentrations of nanoparticles can be incorporated within calcite single crystals, while maintaining the continuity of the lattice and the original rhombohedral morphologies of the crystals. The nanoparticles are perfectly dispersed within the host crystal and at high concentrations are so closely apposed that they exhibit plasmon coupling and induce an unexpected contraction of the crystal lattice. The versatility of this strategy is then demonstrated by extension to alternative host crystals. This simple and scalable occlusion approach opens the door to a novel class of single crystal nanocomposites.
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Dec 2019
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B18-Core EXAFS
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Diamond Proposal Number(s):
[15151]
Abstract: UV activated photocatalysts deposited using chemical vapour deposition have found commercial success as self-cleaning coatings. However, only limited work has been conducted on the use of the more recently discovered visible light activated photocatalysis for this application. Tantalum oxynitride is an established visible light photocatalyst, and in this paper we have investigated the ability of thin films of tantalum oxynitride to photocatalytically degrade a model organic pollutant, stearic acid, and therefore assess the coatings potential for self-cleaning applications. Thin films of tantalum oxide were formed using aerosol assisted chemical vapour deposition (AACVD) of tantalum ethoxide, and then converted into tantalum oxynitride through ammonolysis at temperatures between 550 °C and 750 °C. Investigation of the films using XRD, UV-vis spectroscopy and XAFS identify that amorphous tantalum oxynitride is formed during the ammonolysis, with complete conversion to TaON under conditions of 700 °C for 24 hours. The self-cleaning ability of this film was assessed using stearic acid as the model pollutant, with a degradation rate of 2.5(2) × 1013 molecules per min per cm2 when exposed to a 5-sun solar simulator, equipped with a UV cut-off filter. We therefore conclude that tantalum oxynitride thin films are able to act as self-cleaning coatings through visible light photocatalysis and that films of tantalum oxynitride can be synthesized using a scalable chemical vapour deposition route.
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Jun 2019
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I11-High Resolution Powder Diffraction
I22-Small angle scattering & Diffraction
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Mark A.
Levenstein
,
Clara
Anduix-Canto
,
Yi-Yeoun
Kim
,
Mark A.
Holden
,
Carlos
Gonzalez Nino
,
David C.
Green
,
Stephanie E.
Foster
,
Alexander N.
Kulak
,
Lata
Govada
,
Naomi E.
Chayen
,
Sarah J.
Day
,
Chiu C.
Tang
,
Britta
Weinhausen
,
Manfred
Burghammer
,
Nikil
Kapur
,
Fiona C.
Meldrum
Diamond Proposal Number(s):
[10425, 12352, 17729]
Abstract: The ability to control crystallization reactions is required in a vast range of processes including the production of functional inorganic materials and pharmaceuticals and the prevention of scale. However, it is currently limited by a lack of understanding of the mechanisms underlying crystal nucleation and growth. To address this challenge, it is necessary to carry out crystallization reactions in well‐defined environments, and ideally to perform in situ measurements. Here, a versatile microfluidic synchrotron‐based technique is presented to meet these demands. Droplet microfluidic‐coupled X‐ray diffraction (DMC‐XRD) enables the collection of time‐resolved, serial diffraction patterns from a stream of flowing droplets containing growing crystals. The droplets offer reproducible reaction environments, and radiation damage is effectively eliminated by the short residence time of each droplet in the beam. DMC‐XRD is then used to identify effective particulate nucleating agents for calcium carbonate and to study their influence on the crystallization pathway. Bioactive glasses and a model material for mineral dust are shown to significantly lower the induction time, highlighting the importance of both surface chemistry and topography on the nucleating efficiency of a surface. This technology is also extremely versatile, and could be used to study dynamic reactions with a wide range of synchrotron‐based techniques.
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Mar 2019
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I11-High Resolution Powder Diffraction
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Bartosz
Marzec
,
David C.
Green
,
Mark A.
Holden
,
Alexander S.
Coté
,
Johannes
Ihli
,
Saba
Khalid
,
Alexander
Kulak
,
Daniel
Walker
,
Chiu
Tang
,
Dorothy M.
Duffy
,
Yi-Yeoun
Kim
,
Fiona C.
Meldrum
Diamond Proposal Number(s):
[10137]
Open Access
Abstract: Biomineralisation processes invariably occur in the presence of multiple organic additives, which act in combination to give exceptional control over structures and properties. However, few synthetic studies have investigated the cooperative effects of soluble additives. This work addresses this challenge and focuses on the combined effects of amino acids and coloured dye molecules. The experiments demonstrate that strongly coloured calcite crystals only form in the presence of Brilliant Blue R (BBR) and four of the seventeen soluble amino acids, as compared with almost colourless crystals using the dye alone. The active amino acids are identified as those which themselves effectively occlude in calcite, suggesting a mechanism where they can act as chaperones for individual molecules or even aggregates of dyes molecules. These results provide new insight into crystal–additive interactions and suggest a novel strategy for generating materials with target properties.
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Jun 2018
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I11-High Resolution Powder Diffraction
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David C.
Green
,
Johannes
Ihli
,
Paul D.
Thornton
,
Mark A.
Holden
,
Bartosz
Marzec
,
Yi-Yeoun
Kim
,
Alex N.
Kulak
,
Mark A.
Levenstein
,
Chiu
Tang
,
Christophe
Lynch
,
Stephen E. D.
Webb
,
Christopher J.
Tynan
,
Fiona C.
Meldrum
Diamond Proposal Number(s):
[10137]
Open Access
Abstract: From biomineralization to synthesis, organic additives provide an effective means of controlling crystallization processes. There is growing evidence that these additives are often occluded within the crystal lattice. This promises an elegant means of creating nanocomposites and tuning physical properties. Here we use the incorporation of sulfonated fluorescent dyes to gain new understanding of additive occlusion in calcite (CaCO3), and to link morphological changes to occlusion mechanisms. We demonstrate that these additives are incorporated within specific zones, as defined by the growth conditions, and show how occlusion can govern changes in crystal shape. Fluorescence spectroscopy and lifetime imaging microscopy also show that the dyes experience unique local environments within different zones. Our strategy is then extended to simultaneously incorporate mixtures of dyes, whose fluorescence cascade creates calcite nanoparticles that fluoresce white. This offers a simple strategy for generating biocompatible and stable fluorescent nanoparticles whose output can be tuned as required.
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Nov 2016
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I11-High Resolution Powder Diffraction
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Yi-Yeoun
Kim
,
Mona
Semsarilar
,
Joseph D.
Carloni
,
Kang Rae
Cho
,
Alexander N.
Kulak
,
Iryna
Polishchuk
,
Coit T.
Hendley
,
Paul J. M.
Smeets
,
Lee
Fielding
,
Boaz
Pokroy
,
Chiu C.
Tang
,
Lara A.
Estroff
,
Shefford P.
Baker
,
Steven P.
Armes
,
Fiona
Meldrum
Open Access
Abstract: This article describes an experimentally versatile strategy for producing inorganic/organic nanocomposites, with control over the microstructure at the nano- and mesoscales. Taking inspiration from biominerals, CaCO3 is coprecipitated with anionic diblock copolymer worms or vesicles to produce single crystals of calcite occluding a high density of the organic component. This approach can also be extended to generate complex structures in which the crystals are internally patterned with nano-objects of differing morphologies. Extensive characterization of the nanocomposite crystals using high resolution synchrotron powder X-ray diffraction and vibrational spectroscopy demonstrates how the occlusions affect the short and long-range order of the crystal lattice. By comparison with nanocomposite crystals containing latex particles and copolymer micelles, it is shown that the effect of these occlusions on the crystal lattice is dominated by the interface between the inorganic crystal and the organic nano-objects, rather than the occlusion size. This is supported by in situ atomic force microscopy studies of worm occlusion in calcite, which reveal flattening of the copolymer worms on the crystal surface, followed by burial and void formation. Finally, the mechanical properties of the nanocomposite crystals are determined using nanoindentation techniques, which reveal that they have hardnesses approaching those of biogenic calcites.
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Mar 2016
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I16-Materials and Magnetism
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Diamond Proposal Number(s):
[7277, 7654, 8187]
Abstract: Atomic-level defects such as dislocations play key roles in determining the macroscopic properties of crystalline materials. Their effects range from increased chemical reactivity to enhanced mechanical properties. Dislocations have been widely studied using traditional techniques such as X-ray diffraction and optical imaging. Recent advances have enabled atomic force microscopy to study single dislocations7 in two dimensions, while transmission electron microscopy (TEM) can now visualize strain fields in three dimensions with near-atomic resolution. However, these techniques cannot offer three-dimensional imaging of the formation or movement of dislocations during dynamic processes. Here, we describe how Bragg coherent diffraction imaging (BCDI; refs 11, 12) can be used to visualize in three dimensions, the entire network of dislocations present within an individual calcite crystal during repeated growth and dissolution cycles. These investigations demonstrate the potential of BCDI for studying the mechanisms underlying the response of crystalline materials to external stimuli.
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Jun 2015
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