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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B18-Core EXAFS
I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Matthew A.
Wright
,
T. Wesley
Surta
,
Jae A.
Evans
,
Jungwoo
Lim
,
Hongil
Jo
,
Cara J.
Hawkins
,
Mounib
Bahri
,
Luke M.
Daniels
,
Ruiyong
Chen
,
Marco
Zanella
,
Luciana G.
Chagas
,
James
Cookson
,
Paul
Collier
,
Giannantonio
Cibin
,
Alan V.
Chadwick
,
Matthew S.
Dyer
,
Nigel D.
Browning
,
John B.
Claridge
,
Laurence J.
Hardwick
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[31578]
Open Access
Abstract: Magnesium batteries attract interest as alternative energy-storage devices because of elemental abundance and potential for high energy density. Development is limited by the absence of suitable cathodes, associated with poor diffusion kinetics resulting from strong interactions between Mg2+ and the host structure. V2PS10 is reported as a positive electrode material for rechargeable magnesium batteries. Cyclable capacity of 100 mAh g-1 is achieved with fast Mg2+ diffusion of 7.2[[EQUATION]]10-11-4[[EQUATION]]10-14 cm2s-1. The fast insertion mechanism results from combined cationic redox on the V site and anionic redox on the (S2)2- site; enabled by reversible cleavage of S–S bonds, identified by X-ray photoelectron and X-ray absorption spectroscopy. Detailed structural characterisation with maximum entropy method analysis, supported by density functional theory calculations and projected density of states analysis, reveals that the sulphur species involved in anion redox are not connected to the transition metal centres, spatially separating the two redox processes. This facilitates fast and reversible Mg insertion in which the nature of the redox process depends on the cation insertion site, creating a synergy between the occupancy of specific Mg sites and the location of the electrons transferred.
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Mar 2024
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[30461]
Open Access
Abstract: A 2×2×1 superstructure of the P63/mmc NiAs structure is reported in which kagome nets are stabilized in the octahedral transition metal layers of the compounds Ni0.7Pd0.2Bi, Ni0.6Pt0.4Bi, and Mn0.99Pd0.01Bi. The ordered vacancies that yield the true hexagonal kagome motif lead to filling of trigonal bipyramidal interstitial sites with the transition metal in this family of “kagome-NiAs” type materials. Further ordering of vacancies within these interstitial layers can be compositionally driven to simultaneously yield kagome-connected layers and a net polarization along the c axes in Ni0.9Bi and Ni0.79Pd0.08Bi, which adopt Fmm2 symmetry. The polar and non-polar materials exhibit different electronic transport behaviour, reflecting the tuneability of both structure and properties within the NiAs-type bismuthide materials family.
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Mar 2024
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I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Guopeng
Han
,
Andrij
Vasylenko
,
Luke M.
Daniels
,
Chris M.
Collins
,
Lucia
Corti
,
Ruiyong
Chen
,
Hongjun
Niu
,
Troy D.
Manning
,
Dmytro
Antypov
,
Matthew S.
Dyer
,
Jungwoo
Lim
,
Marco
Zanella
,
Manel
Sonni
,
Mounib
Bahri
,
Hongil
Jo
,
Yun
Dang
,
Craig M.
Robertson
,
Frédéric
Blanc
,
Laurence J.
Hardwick
,
Nigel D.
Browning
,
John B.
Claridge
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[30461, 31578]
Abstract: Fast cation transport in solids underpins energy storage. Materials design has focused on structures that can define transport pathways with minimal cation coordination change, restricting attention to a small part of chemical space. Motivated by the greater structural diversity of binary intermetallics than that of the metallic elements, we used two anions to build a pathway for three-dimensional superionic lithium ion conductivity that exploits multiple cation coordination environments. Li7Si2S7I is a pure lithium ion conductor created by an ordering of sulphide and iodide that combines elements of hexagonal and cubic close-packing analogously to the structure of NiZr. The resulting diverse network of lithium positions with distinct geometries and anion coordination chemistries affords low barriers to transport, opening a large structural space for high cation conductivity.
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Feb 2024
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[23666]
Open Access
Abstract: Understanding the structure-property relationships of materials in order to supress thermal conductivity is crucial for developing efficient thermoelectric generators and thermal barrier coatings. We synthesise two mixed-anion materials, Bi8CsO8SeX7 (X = Cl and Br), with low thermal conductivities of 0.27(2) and 0.22(2) W m-1 K-1 respectively, associated with their c-axes at room temperature. These materials possess a combination of bond strength hierarchies and low frequency Cs+ rattling, which significantly inhibits phonon transport along different crystallographic directions. Due to sharp bond strength contrast between the van der Waals gaps and [Bi2O2]2+ layers, Bi8CsO8SeX7 materials exhibit thermal conductivities <50% of the theoretical minimum when measured along the stacking direction. Conversely, the thermal conductivity associated with the ab-plane is reduced by Cs+ rattling when compared to the structurally and compositionally related BiOCl. This highlights how combining different structural features into one material can aid in the design and identification of new materials with low thermal conductivities.
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Jun 2023
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I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Alexandra
Morscher
,
Benjamin B.
Duff
,
Guopeng
Han
,
Luke M.
Daniels
,
Yun
Dang
,
Marco
Zanella
,
Manel
Sonni
,
Ahmad
Malik
,
Matthew S.
Dyer
,
Ruiyong
Chen
,
Frédéric
Blanc
,
John B.
Claridge
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[23666, 21726]
Open Access
Abstract: Argyrodite is a key structure type for ion-transporting materials. Oxide argyrodites are largely unexplored despite sulfide argyrodites being a leading family of solid-state lithium-ion conductors, in which the control of lithium distribution over a wide range of available sites strongly influences the conductivity. We present a new cubic Li-rich (>6 Li+ per formula unit) oxide argyrodite Li7SiO5Cl that crystallizes with an ordered cubic (P213) structure at room temperature, undergoing a transition at 473 K to a Li+ site disordered F4̅3m structure, consistent with the symmetry adopted by superionic sulfide argyrodites. Four different Li+ sites are occupied in Li7SiO5Cl (T5, T5a, T3, and T4), the combination of which is previously unreported for Li-containing argyrodites. The disordered F4̅3m structure is stabilized to room temperature via substitution of Si4+ with P5+ in Li6+xP1–xSixO5Cl (0.3 < x < 0.85) solid solution. The resulting delocalization of Li+ sites leads to a maximum ionic conductivity of 1.82(1) × 10–6 S cm–1 at x = 0.75, which is 3 orders of magnitude higher than the conductivities reported previously for oxide argyrodites. The variation of ionic conductivity with composition in Li6+xP1–xSixO5Cl is directly connected to structural changes occurring within the Li+ sublattice. These materials present superior atmospheric stability over analogous sulfide argyrodites and are stable against Li metal. The ability to control the ionic conductivity through structure and composition emphasizes the advances that can be made with further research in the open field of oxide argyrodites.
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Nov 2022
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[23666]
Open Access
Abstract: The synthesis, structure, and properties of the three-anion superlattice materials Bi4O4SeBr2 and Bi6O6Se2Cl2 are reported. These materials crystallise in structures that form part of a homologous series of compounds comprised of stackings of BiOCl- and Bi2O2Se-like units. Bi4O4SeBr2 is analogous to Bi4O4Se2Cl2, whereas Bi6O6Se2Cl2 contains an additional Bi2O2Se layer that produces off-centred anions. The band gaps of both materials are indirect, with Eg = 1.15(5) eV, and the materials behave as doped semiconductors with very low thermal conductivities. These materials expand the synthetic scope of multiple anion superlattice materials and, with optimisation, may also be platforms for future thermoelectric materials.
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May 2022
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