I09-Surface and Interface Structural Analysis
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Isabel
Huck
,
Niels
Kubitza
,
Tom
Keil
,
Marius
Schlapp
,
Robert
Winkler
,
Prajna
Bhatt
,
Christoph
Schlueter
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Paweł P.
Michałowski
,
Leopoldo
Molina-Luna
,
Anna
Regoutz
,
Christina S.
Birkel
Diamond Proposal Number(s):
[36180]
Abstract: MAX phases are an extremely versatile family of layered compounds that usually consist of an early to-mid transition metal (M-element), a main group element (mainly groups 13–15) or late transition metal (A-element) and carbon and/or nitrogen (X-element). It is therefore not too surprising that in addition to the roughly 70 compounds with 211 stoichiometry, there exist many solid solutions with mixed elements on the M- and A-site, respectively. Much less common are solid solution phases with mixed elements on both M- and A-site simultaneously (double-site solid solutions), as well as solid solutions on the X-site (carbonitride MAX phases). Challenging these restrictions in the chemical composition space, we present here for the first time (V0.2Cr0.8)2(Ga0.5Ge0.5)(C0.6N0.4) as a new carbonitride member of the MAX phase family, containing solid solutions on all three lattice sites simultaneously. This triple-site solid solution MAX phase is synthesized by high-temperature solid-state methods, and we demonstrate that it is possible to use two different nitrogen-containing precursors (VN and Cr2N), respectively. Structure, morphology and chemical composition are characterized by X-ray powder diffraction (XRD), electron microscopy (SEM/TEM), secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (HAXPES).
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Feb 2026
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I15-1-X-ray Pair Distribution Function (XPDF)
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Caleb J.
Bennett
,
Neha
Bura
,
Frederick P.
Marlton
,
Wen Liang
Tan
,
Tobias A.
Bird
,
Pablo
Botella
,
Peijie
Zhang
,
Benedito Donizeti
Botan-Neto
,
Jose Luis
Rodrigo Ramon
,
Catalin
Popescu
,
Frederico
Alabarse
,
Daniel
Errandonea
,
Brendan J.
Kennedy
Diamond Proposal Number(s):
[36827]
Abstract: A variable temperature X-ray total-scattering study of K2IrCl6 reveals compelling evidence for local symmetry breaking in this material. While the average crystal structure remains cubic down to 11 K, consistent with earlier reports, large anisotropic chloride displacements suggest short-range distortions of the IrCl6 octahedra. Pair distribution function analysis confirms that the local structure is better described by a monoclinic P21/n model featuring a mix of in-phase and out-of-phase octahedral tilts. This behavior mirrors observations in related K2MX6 halides, where thermally driven cubic-to-monoclinic transitions occur. High-pressure synchrotron measurements further reveal two structural transitions: cubic Fm3̅m to tetragonal P4/mnc at 12.0 GPa, and tetragonal to monoclinic P21/n at 15.1 GPa. Both transitions are reversible on decompression. Lattice parameter refinements indicate anisotropic compression with the bulk modulus increasing dramatically from 23 GPa in the cubic phase to 121 GPa in the monoclinic structure. These results demonstrate that both temperature reduction and applied pressure drive K2IrCl6 toward lower-symmetry phases. Overall, this study provides the first direct local-structure evidence of symmetry breaking in K2IrCl6 and highlights the complex interplay among pressure, temperature, and local structure in vacancy-ordered double perovskites.
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Jan 2026
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B22-Multimode InfraRed imaging And Microspectroscopy
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Diamond Proposal Number(s):
[31423]
Open Access
Abstract: A facile approach is demonstrated for synthesizing a mechanically tough ZIF-71 [Zn(dcIm)2; dcIm = 4,5-dichloroimidazole] monoliths with a polymer binder, employing namely poly-methyl methacrylate (PMMA) through a sol-gel process. The addition of a slight polymer binder (∼10 wt.%) to the sol-gel mixture is shown to enhance the mechanical properties such as the elastic modulus, hardness, fracture toughness, strain hardening, and creep behavior of the composite monoliths compared to the pure ZIF-71 monoliths. Nitrogen sorption measurements revealed that the composite monoliths have a high surface area (∼350 m2/g) although it was reduced from ∼600 m2/g due to pore blockage by the polymer. Composite monoliths exhibit less surface cracks and are relatively stiffer but are notably tougher than the pure ZIF-71 monoliths as the fracture toughness tripled from around 0.15 MPa m1/2 to around 0.45 MPa m1/2. Despite the incorporation of a small quantity of polymer in the monolith, this has a significant impact on increasing the mechanical stiffness, hardness and fracture resistance of the resulting monoliths. Creep response observed under a constant load revealed the presence of PMMA incorporated in the composite monolith. Nearfield infrared (IR) nanospectroscopy via nanoFTIR and pseudoheterodyne (PsHet) scattering-Scanning Nearfield Optical Microscopy (s-SNOM) IR imaging on plastically deformed and indented surfaces revealed local chemical structure-mechanical interactions. Our findings suggest that the polymer chains are trapped inside the ZIF-71 structure, thereby improving the mechanical resilience that might pave the way to future scaling up of MOF monoliths for practical applications and durable devices.
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Jan 2026
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I11-High Resolution Powder Diffraction
I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[32893, 39378]
Open Access
Abstract: Sr2MnO2Cu3.5S3 contains mixed-valent Mn ions Mn2+/3+ in axially elongated MnO4S2 octahedra connected via apical sulfide anions to copper-deficient antifluorite-type Cu4-δS3 layers where δ ∼ 0.5. Copper deficiency is charge-compensated by oxidation of Mn 3d states resulting in mixed-valency. The compound is tetragonal in P4/mmm at ambient temperatures (a = 4.016345(1) Å, c = 11.40708(5) Å). Below 190 K, superlattice reflections in diffraction data and an increase in resistivity, signal checkerboard charge-ordering of Mn2+ and Mn3+. The superstructure approximates to a √2a × √2a × 2c expansion of the room temperature cell in space group P42/nmc. However, satellite reflections signal a (3 + 2)D incommensurate modulation of Cu site occupancies in the Cu-deficient sulfide layers coupled with displacements of the sulfur positions; overall the superstructure below 190 K requires description in superspace group P42/nmc(a,0,0)0000(0,a,0)00s0. Analysis of total scattering measurements along with pair distribution functions supports the charge-ordered low temperature model and reveals local order of distinct Mn sites within the higher-temperature charge-disordered regime. Below TN = 27 K, long-range magnetic ordering is A-type antiferromagnetic with distinct moments for Mn2+ and Mn3+ ions directed perpendicular to the MnO2 planes and ordered ferromagnetically. Long-range antiferromagnetic order results from interlayer antiferromagnetic coupling. A metamagnetic transition at 1.1 T corresponds to a change to long-range interlayer ferromagnetic ordering via a spin-reorientation of magnetic moments and is associated with a slight decrease in the charge separation between the Mn sublattices, consistent with observations on mixed-valent perovskite and Ruddlesden–Popper-type oxide manganites.
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Jan 2026
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
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John H.
Burke
,
Maren
Johnsen
,
Rachel F.
Wallick
,
Richard
Gnewkow
,
Dae Young
Bae
,
Aswin
Jyothilakshmi Ravi
,
Thomas C.
Rossi
,
Sebastian
Eckert
,
Mattis
Fondell
,
Matthijs A.
Van Spronsen
,
Richard D.
Schaller
,
Victor
Sosa Alfaro
,
Sang-Jun
Lee
,
Leland B.
Gee
,
Liviu M.
Mirica
,
Renske M.
Van Der Veen
,
Josh
Vura-Weis
Diamond Proposal Number(s):
[33855, 33267]
Abstract: Recent advancements in photocatalysis, photovoltaics, and quantum information science take advantage of electron spin, and determining how spin multiplicity affects electron transfer is key to understanding these phenomena. In this study, we examine how metal spin state affects electronic communication in an organometallic mixed-valence dimer, ferrocenyl cobaltocenium ([FeIICp2CoIIICp2]+). This complex can be photoexcited from its low-spin singlet FeII ground state to form intermediate-spin triplet FeII and high-spin quintet FeII excited states. Using femtosecond optical transient absorption (OTA) spectroscopy with visible (vis), near-infrared (NIR), and short-wave IR (SWIR) probes, supported by time-dependent density functional theory (TD-DFT) calculations, we measure FeIICoIII→FeIIICoII intervalence charge transfer (IVCT) bands in each of the FeII spin states. Mulliken–Hush analysis of the excited-state IVCT bands was used to compute the electronic coupling between the metal centers in all three spin states, which increased as quintet < triplet < singlet. Meanwhile, the peak energy of the bands, and thus the ΔG of the IVCT transition, increased as triplet < quintet < singlet. Then, to directly probe the electronic structure at each metal center, we employed picosecond soft X-ray transient absorption (XTA) spectroscopy at the Fe and Co L3 edges. Our results show that the low-spin and high-spin states of [FeIICp2CoIIICp2]+ are valence-localized, while the intermediate-spin state is partially delocalized. The differences in charge delocalization are attributed to differences in orbital occupation and geometry that affect the free energy and superexchange coupling.
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Jan 2026
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I09-Surface and Interface Structural Analysis
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Arya
Loloee
,
Manuel
Scharrer
,
Tullio S.
Geraci
,
Hui-Fei
Zhai
,
Matt S.
Flores
,
Prajna
Bhatt
,
Aysha A.
Riaz
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Anna
Regoutz
,
Jakoah
Brgoch
,
Jason F.
Khoury
,
Alexandra
Navrotsky
,
Christina S.
Birkel
Diamond Proposal Number(s):
[34325]
Abstract: MAX phases are a class of compounds known for having both metallic and ceramic properties, such as good electrical conductivity, oxidation resistance, and high hardness. The bulk of the research on their properties focuses on those with titanium at the M-site and metals from groups 13 to 15, e.g., aluminum, at the A-site. Here, we expand the properties repertoire with new arsenic-containing A-site solid solutions, V2(As1–xPx)C and V2(As1–xGex)C. The structure and elemental composition of the solid solutions were resolved with powder X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and hard X-ray photoelectron spectroscopy. The electrical resistivity measurements show that both full series are metallic with the parent phases being the most conductive. Thermal analyses show V2GeC is the most oxidation resistant and V2AsC is the least, while substitutions decrease thermal stability, as oxidation resistance of the intermediate compositions shifts toward that of V2AsC. The V2(As1–xGex)C series shows little variation in hardness across compositions, while the incorporation of phosphorus noticeably increases hardness.
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Jan 2026
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I10-Beamline for Advanced Dichroism - scattering
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Yuan
Huang
,
Grigore A.
Timco
,
George F. S.
Whitehead
,
Selena J.
Lockyer
,
Niklas
Geue
,
Zhibo
Qi
,
Adam
Brookfield
,
Peter
Bencok
,
Perdita E.
Barran
,
Nicholas F.
Chilton
,
Michael L.
Baker
,
Eric J. L.
Mcinnes
,
Richard E. P.
Winpenny
Diamond Proposal Number(s):
[34857, 35250]
Abstract: A rare example of a seven-membered heterometallic ring [CrIII6CeIIIF7(O2CtBu)14(THF)2] (MeCN)2 (1) and five eight-membered heterometallic rings, [nPr2NH2][CrIII6LnIII2F8(O2CtBu)17Lx] (2, Ln = Ce, L = HO2CtBu, x = 2, 3, Ln = Y, L = H2O, x = 1, 4, Ln = Gd, L = HO2CtBu, x = 1; 5, Ln = Tb, L = HO2CtBu, x = 1; 6, Ln = Yb, no L) have been synthesized and structurally characterized through X-ray diffraction. The structures consist of eight metals in an octagon, with Cr…Cr and Cr…Ln edges bridged by a fluoride and two carboxylates, while the Ln…Ln edges are bridged by a fluoride and three carboxylates. The magnetisation and susceptibility of these compounds were measured using SQUID magnetometry and electron paramagnetic resonance (EPR) spectroscopy. The magnetic data were fitted with antiferromagnetic exchange interactions between chromium(III) ions, which can be fitted in the {Cr6Y2} complex 3 and these parameters were then used to fit the magnetic properties of the {Cr6Gd2} complex 4 adding in exchange interactions between the CrIII and GdIII The magnetisation and susceptibility below 80 K of 1 and 2 were fitted on the basis of CASSCF-SO calculations at the CeIII site, and showed a weak ferromagnetic interaction between CrIII and CeIII. For 5 and 6 the magnetisation data was fitted by subtracting the data for 3 and treating the residual data as a {Tb2} and {Yb2} dimer respectively. The EPR spectra are rich, and for 3 can be modelled as due to S = 1 and S = 2 states of the {Cr6} chain. The spectra of 1 and 2 are similar, consistent with very weak interactions between the CeIII and the {Cr6} chain, while the spectra of 5 and 6 are different to that of 3, suggesting that the low temperature spectroscopy is due to a spin system in which the LnIII ions interact with the {Cr6} chain.
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Dec 2025
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Diamond Proposal Number(s):
[40403]
Open Access
Abstract: Metal−organic gels (MOGs) and their derived aerogels (MOAs) offer an alternative to crystalline MOFs, combining the coordination-driven tunability with the flexibility, hierarchical porosity, and easy processability of sol–gel polymers. Their noncrystalline nature enables the integration of functional units without crystallization constraints, facilitating diverse uses, and drawing recent attention for photocatalytic applications. Herein we report the design of a new approach to prepare a titanium-based MOA synthesized via a two-step strategy involving a preformed titanium oxo-cluster ([Ti8O8(benzoato)16]), and a subsequent ligand exchange with benzene-1,3,5-tricarboxylato ligands. A combined chemical, microstructural, and NEXAFS analysis confirms the retention of Ti8 cluster and the presence of uncoordinated −COOH groups after meso-macroporous gel formation. Those enabled a subsequent homogeneous incorporation of single-atom site co-catalysts via coordination with Ru, Co, Ni, and Cu complexes bearing terpyridine, bipyridine, and phenanthroline N-ligands. Photocatalytic hydrogen evolution under 365 nm LED irradiation exhibited significant activity (110 μmol·g–1·h–1), which further increased upon functionalization. The MOAs functionalized with Ru- and Cu-terpyridine complexes showed the highest performance (167 and 164 μmol·g–1·h–1, respectively), surpassing even Pt-loaded analogues and highlighting the role of terpyridine in facilitating multielectron storage. The system also showed stable long-term performance up to 24 h.
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Dec 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[35882]
Open Access
Abstract: Here, we report a new tetrakis(formylpyridine) subcomponent that was designed to assemble with anilines and ZnII to afford a set of structurally distinct metal–organic cage structure types. By modulating the metal-to-ligand stoichiometry, we obtained a pseudo-cubic Zn8L6 cage and an open Zn6L3 trigonal prism, the former featuring a diastereomeric configuration of faces and vertices that had not been previously observed. Addition of a tritopic subcomponent yielded a Zn6L3L′2 heteroleptic capped trigonal prism, which could also be prepared via a combination of the homoleptic cages formed by the two individual ligands. The capped trigonal prism encapsulated the pollutant perfluorobutanesulfonate and the oxidant tetracyanoquinodimethane, both technologically relevant guests.
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Nov 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[34390, 34452, 26668]
Open Access
Abstract: A series of new isostructural Ti-oxo clusters containing bridging bidentate 1,n-alkane diolate ligands with the formula [Ti4O4(O2PR2)4{O(CH2)nO}2] (R = Ph, n = 2–5; R = Cy, n = 2–4) were prepared by an alkoxide exchange strategy. The cluster with the 1,5-pentane diolate ligand undergoes productive photoredox chemistry in solution under UV light, resulting in the oxidation of one end of the alkane diolate, and subsequent cyclisation into the lactone tetrahydro-2H-pyran-2-ol, along with formation of a two-electron reduced Ti-oxo cluster stabilised by pyridine. Clusters with smaller bridging alkane diolates show no productive photoredox reactivity, except for R = Cy, n = 3, in which the photoredox products are unstable to further redox processes. Ultrafast electronic absorption spectroscopy studies reveal that all clusters undergo a similar initial photoexcitation step, therefore, productive redox pathways are controlled by the availability of a suitable transition state for rapid proton-coupled electron transfer from the initially generated pendant alkane diolate radicals {Ti–O(CH2)nO˙}. This is dependent on the flexibility (i.e. size) of the 1,n-alkane diolate ligand backbone. Interestingly, the productive photoredox pathway of the 1,5-pentane diolate cluster is turned off when the flexibility of the cluster is restricted in the single crystal phase.
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Nov 2025
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