B18-Core EXAFS
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Diamond Proposal Number(s):
[39526]
Open Access
Abstract: There is increasing interest in using Fe-rich materials in cement, yet the Fe speciation in hydrated cement paste remains poorly understood. This study quantitatively investigates the fate of amorphous Fe in hydrated white Portland cement-fayalitic slag pastes with varying Fe contents cured for 3, 28, and 90 days. The results show that Fe precipitated as ferrihydrite and potentially adsorbed on calcium (alumino)silicate hydrate (C-(A)-S-H) after 3 days of hydration. Afterwards, Fe stabilised in Fe-siliceous hydrogarnet and Fe-adsorbed C-(A)-S-H phases, accounting for ∼15% and ∼ 85% of total reacted Fe, respectively, after hydration for 90 days. The high Fe uptake by C-(A)-S-H was mainly attributed to Fe(III) adsorption rather than Fe(II). Thermodynamic modelling combined with microstructural analysis supported the predominant distribution of Fe on the C-(A)-S-H phase. These findings can advance understanding in using reactive Fe-containing materials in Portland cement pastes and the development of their chemical and physical properties.
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Oct 2026
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[7758, 8615]
Open Access
Abstract: The β′-Gd2(MoO4)3 phase is one of the most well-known multiferroic materials, exhibiting both ferroelectricity and ferroelasticity under ambient conditions, with a complex temperature-pressure phase diagram. In this study, we review the pressure-dependent behavior of the RE2(MoO4)3 compound family (where RE ≡ Pr–Ho), which crystallizes in the β′-phase, with the β-phase being the paraelectric parent structure. Eu, Tb, and Ho molybdates were synthesized via solid-state reactions, ensuring the absence of impurities. High-pressure experiments at DIAMOND synchrotron revealed that the β′-phase persists at low-pressures. At approximately 2 GPa, new peaks emerged, which were refined as a mixture of the β′-phase, other rare-earth molybdates, and oxides, some of which have been detected in earlier stages of synthesis. The β′-phase became distorted with increasing pressure while coexisting with these new phases, whose average unit cell volume was found to lie between that of the β′-phase and the formed distorted phase. Ultimately, this multiphase crystalline decomposition acts as a precursor to pressure-induced amorphization, leading to a loss of long-range periodicity without complete loss of local order. The onsets of pressure-induced decomposition, distortion of the β′-phase and apparent amorphization increase as the ionic radius of the rare-earth element decreases. This scenario of irreversible structural disorder accumulated through phase coexistence is consistent with previous studies and resolves a debate persisting for over half a century.
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Aug 2026
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I18-Microfocus Spectroscopy
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Open Access
Abstract: Mercury (Hg) contamination remains a global environmental challenge, driven by sources such as artisanal gold mining, industrial emissions, and coal combustion. Developing efficient and sustainable remediation strategies is therefore critical. Here we evaluate for the first time the mechanisms controlling Hg and methylmercury (CH3Hg+) removal using nanobiochar derived from açaí (Euterpe oleracea Mart) seed residues and its thiol-functionalized counterpart. Nanobiochar (< 50 nm) was produced via pyrolysis at 600 °C and chemically modified to enhance sorption performance. Thiol functionalization increased maximum sorption capacities by 29% for Hg2+ (from 299 to 385 mg g−1) and 61% for CH₃Hg⁺ (from 102 to 164 ng g−1), while also reducing desorption. Spectroscopic analyses (XPS and EXAFS) revealed that Hg immobilization was primarily driven by the formation of stable Hg–S species, including metacinnabar (β-HgS), highlighting a shift from weaker ionic interactions to covalent bonding. This mechanistic evidence demonstrates that surface functionalization not only enhances sorption capacity but also promotes long-term stability of retained Hg species. By coupling waste valorization with advanced spectroscopic insights, this study provides a novel framework for designing high-performance materials for Hg remediation in contaminated environments.
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Jul 2026
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B18-Core EXAFS
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Diamond Proposal Number(s):
[30629]
Abstract: Geopolymer cements are highly promising materials for long-term immobilisation of Strontium-90 radioactive waste, offering superior durability and cation binding sites compared to conventional Portland cement matrices. This study investigates the influence of prolonged leaching on the Sr immobilisation mechanism and structural integrity of metakaolin-based geopolymers using the ANSI/ANS 16.1 semi-dynamic leaching test. All geopolymers demonstrated high Sr retention, with Leachability Indices at least 14.7 for all samples, significantly exceeding the industry guideline of 6.0, confirming their effectiveness. Importantly, potassium silicate–activated geopolymers exhibited reduced Sr release and substantially lower leaching rates than sodium silicate–activated geopolymers. Multiscale spectroscopic and diffractometric analysis, including synchrotron X-ray absorption spectroscopy and multinuclear high-field solid-state MAS NMR probing 39K, 23Na, 27Al, and 29Si, revealed that the alkali aluminosilicate gel framework remained structurally stable after leaching for 28 days, with no significant alterations to Si and Al bonding environments. Sr release is primarily controlled by diffusion, and the dominant immobilisation mechanism is the formation of insoluble SrCO3. Atomic-level Sr structural analysis using XANES/EXAFS revealed an increase in the average Sr coordination number in both systems after leaching, with a more pronounced rise in potassium-based geopolymers, consistent with enhanced SrCO3 formation. Overall, these findings demonstrate that geopolymers maintain structural integrity during leaching and show for the first time that using potassium rather than sodium as an alkali activator is definitively more advantageous for maximising the long-term effectiveness of geopolymer wasteforms. This demonstrates their strong suitability as wasteforms for the safe long-term immobilisation of Sr-containing radioactive wastes.
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Jul 2026
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[37838]
Open Access
Abstract: The structural behaviour of homoleptic xenon difluoride (XeF2) complexes [M(XeF2)6][SbF6]2 (M = Cu, Zn) under varying temperature and pressure has been investigated, aiming to resolve the disordered Jahn–Teller distortions in the copper complex (CuSb). At 200 K, both CuSb and its zinc analogue (ZnSb) crystallize in a layered CdCl2-type structure with the space group R3. Upon cooling below 170 (CuSb) and 160 K (ZnSb), both systems transition to isostructural phases in P1, with CuSb assuming an ordered Jahn–Teller distortion. The transformation is driven by the shortening and optimization of the Xe⋯F intermolecular contacts, forming stronger and more directional interactions, rather than by Jahn–Teller effects alone. This is supported by the observation of similar transitions in the Jahn–Teller-inactive Zn system. High-pressure experiments up to ∼2.8 GPa at room temperature show the structural stability of the high-symmetry phases, implicating kinetic barriers to further transformation. Additionally, the synthesis and structural characterization of a novel arsenic analogue, [Zn(XeF2)6][AsF6]2 (ZnAs), reveal similar layered motifs but distinct phase behaviour. Symmetry-mode analyses relate all observed phases through distortions of a common CdCl2 aristotype.
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Jul 2026
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B18-Core EXAFS
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Diamond Proposal Number(s):
[33674, 384031, 40080]
Open Access
Abstract: Greener deployment of metal–organic frameworks requires processing strategies that reduce solvent and activation burdens while preserving material performance. Here, we show that freeze-drying provides a simple aqueous post-synthetic isolation strategy for two-dimensional copper-imidazolate nanosheets, BNMG-1, increasing isolated yield and accessibility without disrupting framework chemistry. Compared with conventionally processed BNMG-1, freeze-dried BNMG-1 increases the isolated batch yield from approximately 0.5 to 1.7 g and the accessible surface area from 18 to 70 m2 g−1. Powder X-ray diffraction, vibrational spectroscopy, elemental analysis, microscopy, and Cu K-edge X-ray absorption spectroscopy confirm that freeze-drying retains the Cu–imidazolate framework identity and local Cu coordination. The freeze-dried material retains its principal solid-state structural features following seven-day exposure to air, 1 mM sodium nitrate, artificial seawater and borehole water, although medium-dependent Cu release of up to approximately 14% indicates partial framework transformation in ion-rich media. Functionally, freeze-dried BNMG-1 maintains high Pb(ii) uptake of 488 mg g−1 and strong selectivity over Na, Ca, and Mg. Post-adsorption Cu K-edge XANES and EXAFS reveal that Pb binding induces local coordination reorganisation, with EXAFS fitting supporting a Pb-associated scattering pathway rather than framework collapse. These results establish freeze-drying as a greener processing and isolation strategy for Cu–imidazolate nanosheets and demonstrate how green-processing metrics, environmental transformation analysis, and function-linked local coordination chemistry can be integrated when designing MOFs for aqueous separations and contaminant capture.
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Jul 2026
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B18-Core EXAFS
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Diamond Proposal Number(s):
[31227]
Open Access
Abstract: Nickel (Ni) is a high-value resource in industrial economies with essential uses in ferrous and non-ferrous alloys, electric-vehicle batteries, magnets, and catalysts, but has acute supply-chain risks and is classified as a critical material (or mineral). Here we show that large-scale spontaneous sequestration of nickel occurs in a low-cost calcium silicate hydrate material (CS) under mild conditions. CS takes up Ni
ions rapidly from aqueous solution to achieve loadings as high as 440 kg Ni per tonne CS. This chemistry brings new opportunities in nickel recycling, recovery and environmental clean-up. The Ni sequestration reaction of CS is similar to that previously described (A Hamilton et al., Scientific Reports (2024) 14:7052) for cobalt, although it is about four times faster. Full kinetic and reaction product data are reported. The reaction provides an easy synthesis route to a new Ni-phyllosilicate with a high metal loading, one of a class of materials in active development as catalysts for process-scale water-splitting and reforming reactions.
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Jul 2026
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VMXm-Versatile Macromolecular Crystallography microfocus
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Diamond Proposal Number(s):
[31104]
Open Access
Abstract: In this work, we present the first systematic study of a metal coordination compound (MCC) based on nickel and 1,4-dihydroxyanthraquinone (quinizarin) as an OER catalyst. The Nickel-quinizarin complex referred as NiQ was synthesized using a facile solvothermal route and a crystalline product was obtained that exhibited excellent structural integrity. Structural data of as prepared crystals were obtained by synchrotron microcrystal X-ray diffraction. In the solid state, the Ni(II) metal centre existed in a distorted octahedral geometry. The complex is further stabilized in the solid state by π–π-stacking interactions between the anthraquinone rings. The redox features of complex have been analysed by cyclic voltammetry (CV), suggesting the involvement of Ni(II) metal centres in undergoing an oxidation reaction on the application of an anodic sweep. The electrocatalytic performance of NiQ was evaluated by drop casting NiQ slurry on FTO coated glass plates (NiQ@FTO) directly without needing additional binders or conducting particles and running in 1.0 KOH using a three-electrode system. NiQ@FTO achieved an overpotential as low as 300 mV at 10 mA cm-2, surpassing those of many previously reported coordination complexes-based OER catalysts. Furthermore, it demonstrated excellent stability over prolonged electrolysis with no significant degradation. The present work not only reports a new class of 1,4-Dihydoxyanthraquinone based MCCs as highly active and durable OER catalysts but also offers useful insights into the structure activity relationship, that could be beneficial in future electrocatalysis.
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Jul 2026
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I11-High Resolution Powder Diffraction
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Nataliya L.
Gulay
,
Hai
Lin
,
Batoul
Almoussawi
,
Cara J.
Hawkins
,
Manel
Sonni
,
Marco
Zanella
,
Troy D.
Manning
,
Luke M.
Daniels
,
Matthew S.
Dyer
,
John B.
Claridge
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[36629, 37989]
Open Access
Abstract: During the exploration of the interface between the known structures of perovskite Y2NiTiO6 and hexagonal layered Y2CuTiO6, we have discovered the new phase Y10NixCu1–xTi4O24 (x = 0, 0.5, 1). The structure of Y10CuTi4O24 was solved by means of single-crystal X-ray diffraction, which revealed a layered monoclinic structure, with the space group C2/m, a = 12.2405(1), b = 5.8643(1), c = 7.1729(1) Å, β = 107.083(1)°. The structures of three Y10NixCu1–xTi4O24 (x = 0, 0.5, 1) phases were also refined based on high-resolution powder X-ray diffraction data. Substitution of Cu for Ni causes only minor changes in lattice and atomic parameters. The new phase is related to known Y5Mo2O12-type structures with an extra atomic position occupied by Ni/Cu in the structure of Y10NixCu1–xTi4O24 (x = 0, 0.5, 1). The high-resolution powder X-ray diffraction data revealed peak broadening for the reflections with l = 2n + 1 corresponding to stacking faults originating from the layered structure of Y10NixCu1–xTi4O24. Y10NixCu1–xTi4O24 (x = 0, 0.5, 1) were characterized with respect to their magnetic and optical properties.
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Jul 2026
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I12-JEEP: Joint Engineering, Environmental and Processing
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Abstract: Mn4+-activated far-red emitting phosphors have emerged as a crucial substitute for traditional rare-earth-based luminescent materials. However, the design of Mn4+-type far-red phosphors with high quantum efficiency remains a pivotal challenge because manganese as a typical transition metal element is prone to valence changes, and simultaneously, the 3d–3d characteristic transition of the Mn4+ ion is parity-forbidden. Aiming at this fact, in a Mn-doped Sr4AlNbO8 phosphor (SANO), we present a Ge4+ coblending approach that not only facilitates the directional conversion of coexisting mixed-valence impurities toward Mn4+ but also realizes the breaking of the parity-forbidden transition of Mn4+. DFT calculations and experimental results identify that the Ge4+ ion can act as a modulator to induce the reconstruction of intrinsic matrix defects, which suppress the formation of Mn2+ and Mn5+ impurities. Furthermore, through a comprehensive analysis involving Mn K-edge XAFS spectroscopy, we demonstrate that the Mn4+/Nb5+–O2– bond in the (Mn4+, Nb5+)O6 octahedron will undergo asymmetrical elongation and shrinkage after introducing the Ge4+ ion, which lowers inversion symmetry and thus improves the probability of the d–d transition of Mn4+. The optimal SANO:0.008Mn, 0.05Ge phosphor exhibits a nearly 300-fold PL intensity enhancement at 710 nm, and the quantum efficiency increases from 3% to 86% compared with the original SANO:0.008Mn sample. Actual growth of tomatoes is examined via a reflection-type sunlight-conversion fluorescent membrane as a sunlight-converting system based on the above phosphor. Compared with the blank control group, the fresh weights of tomatoes are increased by 21.89%. These results establish that the reported Mn4+-activated phosphor can hold potential applications for indoor plant cultivation.
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Jul 2026
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