I11-High Resolution Powder Diffraction
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Open Access
Abstract: The first reported phase in the Y2O3–NiO–TiO2 chemical space, the Y2NiTiO6 perovskite undergoes a temperature-induced order–disorder transition. Above ∼1700 K, it adopts the structure of a disordered CaTiO3-type orthorhombic perovskite with a = 5.26939(2), b = 5.60367(2), and c = 7.58137(3) Å, with the B site uniformly occupied by 0.5Ni+0.5Ti. Below this temperature, Y2NiTiO6 adopts rock-salt ordering of the transition metals in a monoclinic unit cell (a = 5.26695(2), b = 5.60164(2), c = 7.57493(2) Å, β = 90.4940(2)°) with 0.9/0.1 ordering of the B site. Ordering of Ni and Ti changes the magnetic properties from spin-glass behavior in the orthorhombic phase to antiferromagnetic order (TN = 17 K) for the monoclinic phase, while the optical properties of both phases remain unchanged across the transition.
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Oct 2025
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I11-High Resolution Powder Diffraction
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Jungwoo
Lim
,
Manel
Sonni
,
Luke M.
Daniels
,
Mounib
Bahri
,
Marco
Zanella
,
Ruiyong
Chen
,
Zhao
Li
,
Alex R.
Neale
,
Hongjun
Niu
,
Nigel D.
Browning
,
Matthew S.
Dyer
,
John B.
Claridge
,
Laurence J.
Hardwick
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[31578]
Open Access
Abstract: LiNiO2 positive electrode materials for lithium-ion batteries have experienced a revival of interest due to increasing technological energy demands. Herein a specific Ti4+ substitution is targeted into LiNiO2 to access new compositions by synthesizing the LiNi1–xTi3x/4O2 solid solution with the aim of retaining Ni3+. Compositions in the range 0.025 ≤ x ≤ 0.2 form nanocomposites of compositionally homogeneous ordered R
m and disordered Fm
m rock salt domains as observed via X-ray and neutron diffraction, and STEM. The disordered rock salt domains stabilize the ordered structure to provide excellent structural reversibility via the formation of coherent interfaces during cycling and enable deep delithiation using a constant voltage charging step without structural degradation. The detrimental structural phase transitions associated with the poor cyclability of LiNiO2 are suppressed to yield a low strain positive electrode material with high capacity retention that offers high-rate capability even under increased cell electrode mass loadings. The composition x = 0.075 (LiNi0.925Ti0.05625O2) affords a 93% capacity retention after 100 cycles (100 mA g−1) and demonstrates high reversible capacities of 125 mAh g−1 even under rates of 3200 mA g−1. LiNi0.925Ti0.05625O2 exhibits exceptional performance at electrode mass loadings (13.6 mg cm−2) comparable to those required for commercial cell applications.
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Jul 2025
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[23666]
Open Access
Abstract: Perovskites offer vast flexibility in tuning subtle distortions in their structures through their innate ability to host a wide range of compositional combinations. Minor changes in composition can dramatically influence the properties observed through structural distortions such as octahedral tilting. In addition to understanding their properties, in magnetic materials, the magnetic structure is also tied to the nuclear structural distortions and can have more complex behavior with changing composition. In this work we report on the magnetic properties, and nuclear and magnetic structures of the solid solution (1 – x)BiFeO3 – (x/2)Ca2Fe4/3W2/3O6. With the exception of BiFeO3, all samples show a weak ferromagnetic behavior arising from spin canting. We find that despite only one structural phase transition occurring from R3c to Pnma in this solid solution, the magnetic phase diagram is far more complex, with four distinct magnetic phases occurring in the compositional range 0.1 < x < 1. Using a combination of neutron and X-ray diffraction, we find that a crossover between long and short Fe–O bond lengths and divergence of Fe–O–Fe bond angles with composition drive the changes in magnetic structure and can be correlated to the resulting magnetic properties.
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Jul 2025
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I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[36629, 31578]
Open Access
Abstract: Apatites are an important mineral-based material family with huge chemical and structural diversity. They were recently implicated in the claims of high-temperature superconductivity in materials labeled LK-99 that display complex phase mixtures containing Pb, Cu, phosphate, and oxide components. We report Cu-substituted lead apatite solid solutions Pb10–xCux(PO4)6O that display two distinct compositional ranges differentiated by structural ordering. For x > 0.5, we observe substitution in the apatite archetype structure, whereas for x < 0.5, we find an apatite superstructure with coupled anion and cation ordering. The 1 × 1 × 2 superstructure in the noncentrosymmetric space group P6̅ (no. 174) for Pb10–xCux(PO4)6O with x < 0.5 exhibits a unique oxygen ordering motif in the hexagonal channels and selective Cu substitution only on two out of seven Pb sites. At x > 0.5 in Pb10–xCux(PO4)6O, Cu cations are introduced onto all Pb sites, which triggers the transition to the archetypical apatite structure, reflecting the coupling of the core structural components of the apatite framework in the ordering pattern.
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Apr 2025
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I11-High Resolution Powder Diffraction
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Matthew J.
Rosseinsky
,
Moinak
Dutta
,
Angelos B.
Canaj
,
Tilen
Knaflič
,
Christopher M.
Collins
,
Troy D.
Manning
,
Hongjun
Niu
,
Luke M.
Daniels
,
Aikaterini
Vriza
,
Luke A.
Johnson
,
Bhupendra
Mali
,
Yuri
Tanuma
,
Todd Wesley
Surta
,
John B.
Claridge
,
Neil
Berry
,
Denis
Arčon
,
Matthew S.
Dyer
Open Access
Abstract: We report the synthesis, structural characterization and magnetic properties of K3coronene, and demonstrate a computational screening workflow designed to accelerate the discovery of metal intercalated polycyclic aromatic hydrocarbon (PAH), a class of materials of interest following reports of superconductivity, but lacking demonstrated and understood characterised materials compositions. Coronene is identified as a suitable PAH candidate from a library of PAHs for potassium intercalation by computational screening of their electronic structure and of the void space in their crystal structures, targeting LUMO similarity to C60 and the availability of suitable sites to accommodate inserted cations. Convex hull calculations with energies from crystal structure prediction based on ion insertion into the identified void space of coronene suggest that the x = 3 composition in Kxcoronene is stable at 0 K, reinforcing the suitability of coronone for experimental investigation. Exploration of reaction conditions and compositions revealed that the mild reducing agent KH allows formation of K3coronene. The structure of K3coronene solved from synchrotron powder X-ray diffraction features extensive reorientation and associated disorder of coronene molecules compared with the parent pristine host. This is driven by K+ intercalation and occupation of sites both within and between the coronene stacks that are partially retained from the parent structure. This disruption of the host structure is greater when three cations are inserted per coronene than in reported metal PAH structures where the maximum ratio of cations to PAH is 2. Superconductivity is not observed, contrary to previous reports on Kxcoronene. The expected localised moment response of coronene3- is suppressed, which may be associated with the combination of extensive disorder and close coronene3- - coronene3- contacts.
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Dec 2024
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B18-Core EXAFS
I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[29271, 31578]
Open Access
Abstract: The catalytic hydrogenolysis process offers the selective production of high-value liquid alkanes from waste polymers. Herein, through normalisation of Ni structure, Ni mass and density, and CeO2 crystallite size, the importance of CeO2 nanocube morphology in the hydrogenolysis of polypropylene (Mw = 12[thin space (1/6-em)]000 g mol−1; Mn = 5000 g mol−1) over Ni/CeO2 catalysts was determined. High liquid productivities (65.9–70.9 gliquid gNi−1 h−1) and low methane yields (10%) were achieved over two different Ni/CeO2 catalysts after 16 h reaction due to the high activity and internal scission selectivity of the supported ultrafine Ni particles (<1.3 nm). However, the Ni/CeO2 nanocube catalyst exhibited higher C–C scission rates (838.1 mmol gNi−1 h−1) than a standard benchmark mixed shape Ni/CeO2 catalyst (480.3 mmol gNi−1 h−1) and represents a 75% increase in depolymerisation activity. This led to shorter hydrocarbon chains achieved by the nanocube catalyst (Mw = 2786 g mol−1; Mn = 1442 g mol−1) when compared to the mixed shape catalyst (Mw = 4599 g mol−1; Mn = 2530 g mol−1). The enhanced C–C scission rate of the nanocube catalyst was determined to arise from a combination of improved H-storage and favourable basic properties, with higher weak basic site density key to facilitate a greater degree of hydrocarbon chain adsorption.
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Dec 2024
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B18-Core EXAFS
I11-High Resolution Powder Diffraction
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Matthew A.
Wright
,
Jungwoo
Lim
,
Raul A.
Pacheco Muino
,
Anna E.
Krowitz
,
Cara J.
Hawkins
,
Mounib
Bahri
,
Luke M.
Daniels
,
Ruiyong
Chen
,
Luciana
Gomes Chagas
,
James
Cookson
,
Paul
Collier
,
Alan V.
Chadwick
,
Nigel D.
Browning
,
John B.
Claridge
,
Laurence J.
Hardwick
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[31578]
Open Access
Abstract: V2Se9 displays facile electrochemical insertion of up to 1.6 Mg2+ per unit formula with fast diffusion (coefficients of 10-10 – 10-12 cm2 s-1) surpassing best-in-class materials like Mo6S8. Detailed structural characterization of synchrotron X-ray diffraction data with ab initio Maximum Entropy Method analysis reveals Mg2+ insertion onto octahedral sites within the large vdW space between [V4Se18]∞ chains. Fast rate performance is attributed to low structural perturbation and low diffusion barriers, calculated by bond valence pathway analysis, resulting from the low charge-per-size of anionic selenium. X-ray photoelectron spectroscopy and X-ray absorption spectroscopy reveal that reversible insertion of Mg2+ is facilitated by V5+/V3+ redox. V2Se9 demonstrates that selenides, despite their larger molecular weight, offer potential as fast rate positive electrode materials for magnesium batteries over well-explored oxides and sulfides.
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Oct 2024
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I11-High Resolution Powder Diffraction
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Nataliya
Hulai
,
Marco
Zanella
,
Craig
Robertson
,
Daniel
Ritchie
,
Manel
Sonni
,
Matthew A.
Wright
,
Jon A.
Newnham
,
Cara J.
Hawkins
,
Jayne
Whitworth
,
Bhupendra
Mali
,
Hongjun
Niu
,
Matthew S.
Dyer
,
Christopher M.
Collins
,
Luke M.
Daniels
,
John B.
Claridge
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[31578]
Open Access
Abstract: Two compounds were discovered in the well-studied BaO-Y2O3-SiO2 phase field. Two different experimental routines were used for the exploration of this system due to the differences of synthetic conditions and competition with a glass field. The first phase Ba5Y13[SiO4]8O8.5 was isolated through a combination of energy dispersive X-ray spectroscopy analysis and diffraction techniques which guided the exploration. The second phase Ba3Y2[Si2O7]2 was located using iterative algorithmic identification of target compositions. The structure solution of the new compounds was aided by continuous rotation electron diffraction, and the structures were refined against combined synchrotron and neutron time-of-flight powder diffraction. Ba5Y13[SiO4]8O8.5 crystallizes in I-42m, a = 18.92732(1), c = 5.357307(6) Å and represents its own structure type which combines elements of structures of known silicates embedded in columns of interconnected yttrium-centred polyhedra characteristic of high-pressure phases. Ba3Y2[Si2O7]2 has P21 symmetry with a pseudo-tetragonal cell (a = 16.47640(4), b = 9.04150(5), c = 9.04114(7) Å, β = 90.0122(9)°) and is a direct superstructure of the Ca3BaBi[P2O7]2 structure. Despite the lower symmetry, the structure of Ba3Y2[Si2O7]2 retains disorder in both Ba/Y sites and disilicate network, thus presenting a superposition of possible locally-ordered fragments. Ba5Y13[SiO4]8O8.5 has low thermal conductivity of 1.04(5) W m-1 K-1 at room temperature. The two discovered phases provide a rich structural platform for further functional material design. The interplay of automated unknown phase composition identification with multiple diffraction methods offers acceleration of the time-consuming exploration of high-dimensional chemical spaces for new structures.
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Sep 2024
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I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Guopeng
Han
,
Luke M.
Daniels
,
Andrij
Vasylenko
,
Kate A.
Morrison
,
Lucia
Corti
,
Chris M.
Collins
,
Hongjun
Niu
,
Ruiyong
Chen
,
Craig M.
Robertson
,
Frédéric
Blanc
,
Matthew S.
Dyer
,
John B.
Claridge
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[31578, 36629]
Open Access
Abstract: Ge4+ substitution into the recently discovered superionic conductor Li7Si2S7I is demonstrated by synthesis of Li7Si2–xGexS7I, where x ≤ 1.2. The anion packing and tetrahedral silicon location of Li7Si2S7I are retained upon substitution. Single crystal X-ray diffraction shows that substitution of larger Ge4+ for Si4+ expands the unit cell volume and further increases Li+ site disorder, such that Li7Si0.88Ge1.12S7I has one Li+ site more (sixteen in total) than Li7Si2S7I. The ionic conductivity of Li7Si0.8Ge1.2S7I (x = 1.2) at 303 K is 1.02(3) × 10–2 S cm–1 with low activation energies for Li+ transport demonstrated over a wide temperature range by AC impedance and 7Li NMR spectroscopy. All sixteen Li+ sites remain occupied to temperatures as low as 30 K in Li7Si0.88Ge1.12S7I as a result of the structural expansion. This differs from Li7Si2S7I, where the partial Li+ site ordering observed below room temperature reduces the ionic conductivity. The suppression of Li+ site depopulation by Ge4+ substitution retains the high mobility to temperatures as low as 200 K, yielding low temperature performance comparable with state-of-the-art Li ion conducting materials.
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Jun 2024
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I19-Small Molecule Single Crystal Diffraction
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Cara J.
Hawkins
,
Jon A.
Newnham
,
Batoul
Almoussawi
,
Nataliya L.
Gulay
,
Samuel L.
Goodwin
,
Marco
Zanella
,
Troy D.
Manning
,
Luke M.
Daniels
,
Matthew S.
Dyer
,
Tim D.
Veal
,
John B.
Claridge
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[30461]
Open Access
Abstract: Mixed anion halide-chalcogenide materials have recently attracted attention for a variety of applications, owing to their desirable optoelectronic properties. We report the synthesis of a previously unreported mixed-metal chalcohalide material, CuBiSeCl2 (Pnma), accessed through a simple, low-temperature solid-state route. The physical structure is characterized through single-crystal X-ray diffraction and reveals significant Cu displacement within the CuSe2Cl4 octahedra. The electronic structure of CuBiSeCl2 is investigated computationally, which indicates highly anisotropic charge carrier effective masses, and by experimental verification using X-ray photoelectron spectroscopy, which reveals a valence band dominated by Cu orbitals. The band gap is measured to be 1.33(2) eV, a suitable value for solar absorption applications. The electronic and thermal properties, including resistivity, Seebeck coefficient, thermal conductivity, and heat capacity, are also measured, and it is found that CuBiSeCl2 exhibits a low room temperature thermal conductivity of 0.27(4) W K–1 m–1, realized through modifications to the phonon landscape through increased bonding anisotropy.
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Apr 2024
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