I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[32893]
Abstract: Tetragonal tungsten bronzes (TTBs) have emerged as a promising structure type for Pb- and Bi-free ferroics for high–temperature stable multilayer ceramic capacitors. In this work, A- and B-site co-doped Sr2-2zNaCazYzNb5-zZrzO15 (with z = 0 to 0.075; SNN) ceramics exhibited a flattening of relative permittivity across a wide temperature range covering two dielectric anomalies: T2, a ferroelectric to paraelectric transition between 229 °C and 297 °C, and T1, a relaxor-ferroelectric peak between -8 °C and -70 °C. Rietveld refinement of synchrotron X-ray powder diffraction of the SNN ceramics using an orthorhombic Ama2 model, identified changes in the temperature evolution with doping of lattice parameters a, b and c, plus symmetry–driven distortion and strain modes including the ferroelectric polar mode distortion amplitude along c (
. A-site doping of smaller Ca2+ and Y3+ ions (for Sr2+), increases A-site disorder, working in combination with B-site doping of less polarisable Zr4+ ions (for Nb5+), disrupting long range commensurate ferroelectric ordering, via rigid unit-like octahedral tilting. This leads to an incommensurate modulation, whose associated strain is accommodated by an increasing stacking fault density, confirmed by TEM. This destabilises the ferroelectric polar mode (
onset temperature decreases, lowering T2), leading to increasing in orthorhombic strain in the ab plane (c axis compresses, inflection points of a and c at T1 diverge). Resulting in an increase in relaxor-like frequency dispersion of permittivity at T1 and a reduced negative thermal expansion of the c axis between T2 and T1, leading to a permittivity flattening.
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Apr 2026
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[25166]
Open Access
Abstract: The crystallization of a trimetallic cobalt–molybdenum–sodium metal–organic framework, poly[μ-benzene-1,3,5-tricarboxylato-tetra-μ-oxido-cobaltmolybdenumtrisodium], UOW-10 or [Na3Co(MoO4)(BTC)]n, is achieved by solvothermal synthesis using benzene-1,3,5-tricarboxylic acid (H3BTC, C9H6O6) as a ligand precursor, Na2MoO4·2H2O and Co(NO3)2·2H2O as metal sources, and N,N-dimethylformamide (DMF) as the solvent. 3D electron diffraction (3D ED) reveals that the structure crystallizes in the monoclinic space group P21/c, with lattice parameters of a = 9.718 (2), b = 18.250 (3), c = 6.892 (9) Å, α = γ = 90, β = 96.156 (15)°, V = 1214.7 (4) Å3 and Z = 4. The phase purity of the bulk sample was confirmed using synchrotron powder X-ray diffraction. The organic ligands form a 2D layer, where cobalt and molybdenum are found, with sodium cations located between the layers. There are four crystallographically distinct sodium sites: three exhibit a distorted octahedral coordination geometry, while the remaining site is seven-coordinate. The cobalt has trigonal bipyramidal coordination geometry and molybdenum exhibits a tetrahedral coordination geometry. Half the sodium cations in the structure forms 1D column-like motifs via shared oxygen edges along the crystallographic c axis, which are cross-linked in b by the cobalt and molybdenum sites via bridging O atoms, while the other half of the sodium cations form 2D ribbons in the ac plane, propagating along c, linked by sharing oxygen edges and faces. The optical properties of UOW-10 were investigated through the use of UV–Vis spectroscopy, showing a bandgap of 1.8 eV. Deconvolution of the features in the visible-light region reveals that four peaks are present, which can all be ascribed to the d–d transitions from the trigonal bipyramidal cobalt. By means of thermogravimetric analysis (TGA) and variable-temperature powder X-ray diffraction (VT-PXRD), it is demonstrated that the material has thermal stability to 410 °C, after which structure collapse occurs, leading to a mixture of Na2MoO4, CoO and Co3Mo above 900 °C.
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Mar 2026
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B18-Core EXAFS
I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[25166, 14239]
Open Access
Abstract: Investigation of the earliest stages of hydrothermal reactions between KRuO4 and either Sr(NO3)2 or SrO2 allows the isolation of phase-pure SrRuO3(OH)2, a hitherto uncharacterized Ru(VI) oxyhydroxide, previously mentioned in the literature as SrRuO4·H2O. Further exploration of synthesis conditions with excess of strontium salt yields a second Ru(VI) phase, Sr3Ru2O8(OH)2 at 200 °C. Both structures were solved by 3D-electron diffraction and refined using powder neutron diffraction (SrRuO3(OH)2: monoclinic P21/n, a = 9.9903(3) Å, b = 7.7023(2) Å, c = 17.3677(6) Å, β = 89.353(2)°; Sr3Ru2O8(OH)2: tetragonal P4̅, a = 13.2206(5) Å c = 5.4852(2) Å). The two Ru(VI) materials each contain isolated trigonal bipyramidal ruthenium centers with axially positioned hydroxides with longer Ru–OH bond distances than the equatorial Ru–O distances. Infrared spectroscopy corroborates the presence of hydroxide, with O–H stretching bands that are red-shifted upon deuteration. X-ray absorption near-edge spectroscopy at the Ru K-edge confirms the +6 oxidation state of Ru, and magnetization measurements show two unpaired electrons per Ru associated with the 4d2 electronic configuration in both materials. The crystal structures, particularly the local environment of Ru, are compared with other reported Ru(VI) compounds, and derived bond valence sum parameters give consistent results for ruthenate(VI) oxides and oxyhydroxides.
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Sep 2025
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[25166]
Open Access
Abstract: The synthesis and structural characterisation of a cerium (III) MOF, UOW-11, is reported. The material is constructed using the sustainably sourced 2,5-furandicarboxylate (FDC) linker under solvothermal conditions in N,N-dimethylformamide (DMF) solvent and scalable to gram-scale production. Single-crystal analysis using 3D electron diffraction reveals a unique framework architecture, P21/n. space group, with composition [Ce4(FDC)7(DMF)2.36](DMA)2 that has a structure containing four cerium(III) sites that are connected via bridging FDC ligands to give a 3D extended anionic framework counterbalanced by occluded dimethylammonium (DMA) cations, formed via partial decomposition of DMF. Upon exposure to water, UOW-11 undergoes a structural transformation, forming a second, structurally distinct Ce(III) coordination polymer, [Ce2(FDC)2(H2O)10]FDC·6H2O, UOW-2(Ce), which crystallises in the triclinic space group P1 . The asymmetric unit comprises two Ce³⁺ ions, coordinated by two FDC²⁻ ligands, ten water molecules, with one additional uncoordinated FDC²⁻ ligand, and six occluded water molecules. The transformation leads to significant changes in coordination geometry and composition, including the loss of DMA and a different Ce:FDC ratio, consistent with a dissolution–recrystallisation mechanism. Monitoring the conversion using in situ infra-red spectroscopy shows the transformation is complete after ~3 hours at room temperature.
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Sep 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[36775, 26668]
Open Access
Abstract: A variable-temperature and pressure single-crystal diffraction study of hybrid improper ferroelectric Sr3Sn2O7 is reported. In combination with symmetry analysis, we reveal that the application of pressure and temperature induce distinct phase transition pathways, driven by a differing response of the octahedral rotations to these stimuli. Contrary to what has been previously predicted, we observe the ferroelectric to paraelectric phase transition between 10.17(18) and 12.13(14) GPa, meaning the hybrid improper ferroelectric phase remains stable to significantly higher pressures than expected.
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Jun 2025
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[25166]
Open Access
Abstract: We report two three-dimensional metal-organic frameworks constructed from Fe3+ and the ligand, 2,5-furandicarboxylate (FDC) that can be derived from biomass. One contains an unprecedented infinite-rod-shaped building unit, and the other is the first crystalline framework of FDC that contains solely iron in the metal nodes. The materials are formed as microcrystals and their structures determined using 3D-electron diffraction with the bulk confirmed by powder XRD. UOW-7, NaFe5O3(FDC)4(CH3COO)2 is a bimetallic structure with acetate as co-ligand, constructed from infinite chains of iron octahedra, wherein tetramers comprising edge-sharing pairs linked by corner sharing octahedra are crosslinked by FDC ligands. In contrast, UOW-8, Fe2O(FDC)2(H2O)2]·(H2O)4 contains a rare form of tetrameric building unit, cross-linked by FDC, and having Fe-bound water as well as occluded water. The materials crystallise under hydrothermal conditions and are water-stable coordination polymers with no measurable free pore space. The catalytic ability of UOW-7 and UOW-8 is, nevertheless, established in the reduction of 4-nitrophenol to 4-aminophenol by borohydride, where both act as recyclable, catalysts to give ~100% yield of the product without use of precious metals. UOW-8 is found to have the more favourable reaction kinetics, likely due to the presence of surface Lewis acidic Fe3+ centres that enhance substrate binding.
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Mar 2025
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I11-High Resolution Powder Diffraction
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S.
Vaidya
,
A.
Hernández-Melián
,
J. P.
Tidey
,
S. P. M.
Curley
,
S.
Sharma
,
P.
Manuel
,
C.
Wang
,
G. L.
Hannaford
,
S. J.
Blundell
,
Z. E.
Manson
,
J. L.
Manson
,
J.
Singleton
,
T.
Lancaster
,
R. D.
Johnson
,
P. A.
Goddard
Open Access
Abstract: We investigate the magnetic properties of 𝑆=1 antiferromagnetic diamond-lattice, Ni𝑋2(pyrimidine)2 (𝑋=Cl, Br), hosting a single-ion anisotropy (SIA) orientation which alternates between neighboring sites. Through neutron diffraction measurements of the 𝑋=Cl compound, the ordered state spins are found to align collinearly along a pseduo-easy axis, a unique direction created by the intersection of two easy planes. Similarities in the magnetization, exhibiting spin-flop transitions, and the magnetic susceptibility in the two compounds imply that the same magnetic structure and a pseduo-easy axis is also present for 𝑋=Br. We estimate the Hamiltonian parameters by combining analytical calculations and Monte Carlo (MC) simulations of the spin-flop and saturation field. The MC simulations also reveal that the spin-flop transition occurs when the applied field is parallel to the pseduo-easy axis. Contrary to conventional easy-axis systems, there exist field directions perpendicular to the pseduo-easy axis for which the magnetic saturation is approached asymptotically and no symmetry-breaking phase transition is observed at finite fields.
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Nov 2024
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[30815]
Open Access
Abstract: Van der Waals (vdW) magnets offer unique opportunities for exploring magnetism in the 2D limit. Metal-organic magnets (MOM) are of particular interest as the functionalisation of organic ligands can control their physical properties. Here, we demonstrate tuning of mechanical and magnetic function of a noncollinear vdW ferromagnet, NiCl2(btd) (btd = 2,1,3-benzothiadiazole), through creating solid-solutions with the oxygen-substituted analogue ligand 2,1,3-benzoxadiazole (bod). We synthesise solid-solutions, NiCl2(btd)1–x(bod)x , up to x = 0.33 above which we find mixtures form, primarily composed of a new 1D coordination polymer NiCl2(bod)2. Magnetometry on this series shows that bod incorporation reduces the coercivity significantly (up to 60%), without significantly altering the ordering temperatures. Our high pressure synchrotron diffraction measurements up to 0.4 GPa demonstrate that the stiffest axis is the b axis, through the Ni-N-(O/S)-N-Ni bonds, and the softest is the interlayer direction. Doping with bod fine-tunes this compressibility, softening the layers, but stiffening the interlayer axis. This demonstrates that substitution of organic ligands in vdW MOMs can be used to realise targetted magnetic and mechanical properties.
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Oct 2024
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I11-High Resolution Powder Diffraction
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Struan
Simpson
,
Cameron A. M.
Scott
,
Fernando
Pomiro
,
Jeremiah P.
Tidey
,
Urmimala
Dey
,
Fabio
Orlandi
,
Pascal
Manuel
,
Martin R.
Lees
,
Zih-Mei
Hong
,
Wei-Tin
Chen
,
Nicholas C.
Bristowe
,
Mark S.
Senn
Diamond Proposal Number(s):
[32893]
Open Access
Abstract: Magnetoelectric multiferroics hold great promise for the development of new sustainable memory devices. However, practical applications of many existing multiferroic materials are infeasible due to the weak nature of the coupling between the magnetic and electrical orderings, meaning new magnetoelectric multiferroics featuring intrinsic coupling between their component orderings are sought instead. Here, we apply a symmetry-informed design approach to identify and realize the new manganite perovskite CeBaMn2O6 in which magnetoelectric coupling can be achieved via an intermediary non-polar structural distortion. Through first-principles calculations, we demonstrate that our chosen prototype system contains the required ingredients to achieve the desired magnetoelectric coupling. Using high-pressure/high-temperature synthesis conditions, we have been able to synthesize the CeBaMn2O6 perovskite system for the first time. Our subsequent neutron and electron diffraction measurements reveal that the desired symmetry-breaking ingredients exist in this system on a nanoscopic length scale, enabling magnetoelectric nanoregions to emerge within the material. Through this work, we showcase the potential of the new CeBaMn2O6 perovskite material as a promising system in which to realize strong magnetoelectric coupling, highlighting the potential of our symmetry-informed design approach in the pursuit of new magnetoelectric multiferroics for next-generation memory devices.
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Aug 2024
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[25166]
Open Access
Abstract: The tetragonal tungsten bronze, Sr2NaNb5O15, shows promise for application in high-temperature high-efficiency capacitors vital for the sustainable energy revolution. Previously, the structural complexity of this and related materials has obscured the mechanisms underpinning two large anomalies in relative permittivity (εr) which give rise to their exceptionally broad dielectric response. Here, we comprehensively investigate the structural evolution from −173 to 627 °C, combining electron, X-ray and neutron diffraction, electron microscopy, and first principles electronic structure calculations to unambiguously identify the structural origins of both anomalies. The peak in εr at 305 °C is associated with a polar-nonpolar phase transition, wherein cations displace along the c axis. Guided by DFT, we identify a further transition upon cooling, associated with the second peak at −14 °C, linked to the softening of an in-plane polar distortion with a correlation length limited by ferroelastic nano-domains arising from rigid-unit-like tilting of NbO6 octahedra at high temperature, imparting relaxor-like behaviour. Thus, the two dielectric anomalies in Sr2NaNb5O15 are associated with two distinct crystallographic phase transitions and their interplay with a microstructure that arises from a third, non-polar structural distortion. Chemical control of these will enable development of tuneable materials with dielectric properties suitable for high-temperature energy storage applications.
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May 2024
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