Search Results

You searched for all publications:

with publication states 'Published (Approved)'
published in journal 'Chemistry Of Materials'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

125 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
	BaBi2O6: A promising n-type thermoelectric oxide with the pbsb2o6crystal structure Kieran B. Spooner , Alex M. Ganose , W. W. Winnie Leung , John Buckeridge , Benjamin A. D. Williamson , Robert G. Palgrave , David O. Scanlon Chemistry Of Materials 12 DOI: 10.1021/acs.chemmater.1c02164 Show Abstract ▼ Abstract: Thermoelectric materials offer the possibility of enhanced energy efficiency due to waste heat scavenging. Based on their high-temperature stability and ease of synthesis, efficient oxide-based thermoelectrics remain a tantalizing research goal; however, their current performance is significantly lower than the industry standards such as Bi2Te3 and PbTe. Among the oxide thermoelectrics studied thus far, the development of n-type thermoelectric oxides has fallen behind that of p-type oxides, primarily due to limitations on the overall dimensionless figure of merit, or ZT, by large lattice thermal conductivities. In this article, we propose a simple strategy based on chemical intuition to discover enhanced n-type oxide thermoelectrics. Using state-of-the-art calculations, we demonstrate that the PbSb2O6-structured BaBi2O6 represents a novel structural motif for thermoelectric materials, with a predicted ZT of 0.17–0.19. We then suggest two methods to enhance the ZT up to 0.22, on par with the current best earth-abundant n-type thermoelectric at around 600 K, SrTiO3, which has been much more heavily researched. Our analysis of the factors that govern the electronic and phononic scattering in this system provides a blueprint for optimizing ZT beyond the perfect crystal approximation.	Sep 2021
I09-Surface and Interface Structural Analysis	Electrochemical oxidative fluorination of an oxide perovskite Nicholas H. Bashian , Mateusz Zuba , Ahamed Irshad , Shona M. Becwar , Julija Vinckeviciute , Warda Rahim , Kent J. Griffith , Eric T. Mcclure , Joseph K. Papp , Bryan D. Mccloskey , David O. Scanlon , Bradley F. Chmelka , Anton Van Der Ven , Sri R. Narayan , Louis F. J. Piper , Brent Melot Chemistry Of Materials DOI: 10.1021/acs.chemmater.1c01594 Diamond Proposal Number(s): [22250] Show Abstract ▼ Abstract: We report on the electrochemical fluorination of the A-site vacant perovskite ReO3 using high-temperature solid-state cells as well as room-temperature liquid electrolytes. Using galvanostatic oxidation and electrochemical impedance spectroscopy, we find that ReO3 can be oxidized by approximately 0.5 equiv of electrons when in contact with fluoride-rich electrolytes. Results from our density functional theory calculations clearly rule out the most intuitive mechanism for charge compensation, whereby F-ions would simply insert onto the A-site of the perovskite structure. Operando X-ray diffraction, neutron total scattering measurements, X-ray spectroscopy, and solid-state 19F NMR with magic-angle spinning were, therefore, used to explore the mechanism by which fluoride ions react with the ReO3 electrode during oxidation. Taken together, our results indicate that a complex structural transformation occurs following fluorination to stabilize the resulting material. While we find that this process of fluorinating ReO3 appears to be only partially reversible, this work demonstrates a practical electrolyte and cell design that can be used to evaluate the mobility of small anions like fluoride that is robust at room temperature and opens new opportunities for exploring the electrochemical fluorination of many new materials.	Jul 2021
	Guest-anion-induced rotation-restricted emission in UiO-66-NH2 and advanced structure elucidation Qi Xue , Ka Hin Chan , Cheuk Ki Yim , Bryan Kit Yue Ng , Tianxiang Chen , Sarah J. Day , Chiu Tang , Shogo Kawaguchi , Kwok-Yin Wong , Tsz Woon Benedict Lo Chemistry Of Materials DOI: 10.1021/acs.chemmater.1c01674 Show Abstract ▼ Abstract: We report the guest-anion-induced photoluminescence enhancement of metal–organic frameworks (UiO-66-NH2), first based upon diffraction and computational evidence. We found that only limited anions, namely, carbonate and fluoride, can lead to a significant enhancement in photoluminescence, whereas their related anions, such as acetate and chloride, cannot. The optimized crystal structures reveal that the guest carbonate and fluoride ions interact with four framework amino functional groups through hydrogen bonding (ca. 1.6–1.7 Å) that ultimately forms a quaternary (−N(H))4···X– molecular bridge around the nodal center. Hence, the hydrogen-bonded molecular bridge not only restricts the intermolecular C–C rotation of the linker molecules but also greatly perturbs the electronic densities between the guest anions and the framework amino groups.	Jul 2021
B18-Core EXAFS	Structural origins of voltage hysteresis in the Na-ion cathode P2–Na0.67[Mg0.28Mn0.72]O2: A combined spectroscopic and density functional theory study Euan N. Bassey , Philip J. Reeves , Michael A. Jones , Jeongjae Lee , Ieuan D. Seymour , Giannantonio Cibin , Clare P. Grey Chemistry Of Materials 68 DOI: 10.1021/acs.chemmater.1c00248 Diamond Proposal Number(s): [24303] Open Access Show Abstract ▼ Abstract: P2-layered sodium-ion battery (NIB) cathodes are a promising class of Na-ion electrode materials with high Na+ mobility and relatively high capacities. In this work, we report the structural changes that take place in P2–Na0.67[Mg0.28Mn0.72]O2. Using ex situ X-ray diffraction, Mn K-edge extended X-ray absorption fine structure, and 23Na NMR spectroscopy, we identify the bulk phase changes along the first electrochemical charge–discharge cycle—including the formation of a high-voltage “Z phase”, an intergrowth of the OP4 and O2 phases. Our ab initio transition state searches reveal that reversible Mg2+ migration in the Z phase is both kinetically and thermodynamically favorable at high voltages. We propose that Mg2+ migration is a significant contributor to the observed voltage hysteresis in Na0.67[Mg0.28Mn0.72]O2 and identify qualitative changes in the Na+ ion mobility.	Jun 2021
I11-High Resolution Powder Diffraction	Li6SiO4Cl2: A hexagonal argyrodite based on antiperovskite layer stacking Alexandra Morscher , Matthew S. Dyer , Benjamin B. Duff , Guopeng Han , Jacinthe Gamon , Luke Daniels , Yun Dang , T. Wesley Surta , Craig M. Robertson , Frédéric Blanc , John B. Claridge , Matthew J. Rosseinsky Chemistry Of Materials DOI: 10.1021/acs.chemmater.1c00157 Diamond Proposal Number(s): [23666] Open Access Show Abstract ▼ Abstract: A hexagonal analogue, Li6SiO4Cl2, of the cubic lithium argyrodite family of solid electrolytes is isolated by a computation–experiment approach. We show that the argyrodite structure is equivalent to the cubic antiperovskite solid electrolyte structure through anion site and vacancy ordering within a cubic stacking of two close-packed layers. Construction of models that assemble these layers with the combination of hexagonal and cubic stacking motifs, both well known in the large family of perovskite structural variants, followed by energy minimization identifies Li6SiO4Cl2 as a stable candidate composition. Synthesis and structure determination demonstrate that the material adopts the predicted lithium site-ordered structure with a low lithium conductivity of ∼10–10 S cm–1 at room temperature and the predicted hexagonal argyrodite structure above an order–disorder transition at 469.3(1) K. This transition establishes dynamic Li site disorder analogous to that of cubic argyrodite solid electrolytes in hexagonal argyrodite Li6SiO4Cl2 and increases Li-ion mobility observed via NMR and AC impedance spectroscopy. The compositional flexibility of both argyrodite and perovskite alongside this newly established structural connection, which enables the use of hexagonal and cubic stacking motifs, identifies a wealth of unexplored chemistry significant to the field of solid electrolytes.	Mar 2021
I11-High Resolution Powder Diffraction	Switching between proper and hybrid-improper polar structures via cation substitution in A2La(TaTi)O7 (A = Li, Na) Subhadip Mallick , Andrew Dominic Fortes , Weiguo Zhang , P. Shiv Halasyamani , Michael A. Hayward Chemistry Of Materials 23 DOI: 10.1021/acs.chemmater.1c00599 Diamond Proposal Number(s): [18786] Show Abstract ▼ Abstract: Neutron powder diffraction data indicate that Li2La(TaTi)O7 adopts a polar, a–a–c+/a–a–c+ distorted, n = 2 Ruddlesden–Popper structure described in space group A21am (#36), consistent with a hybrid-improper stabilization of the polar structure via a trilinear coupling between the X3–, X2+, and Γ5– distortion modes. In contrast, Na2La(TaTi)O7 adopts a polar, a–a–c–/a–a–(-c–) distorted, n = 2 Ruddlesden–Popper structure described in space group Pna21 (#33) with the polar Γ3– distortion mode apparently stabilized by a second-order Jahn–Teller distortion of the d0 Ta5+/Ti4+ cations. The change in class of polar distortion of the A2La(TaTi)O7 framework, from hybrid improper (trilinearly coupled) to proper (second-order Jahn–Teller stabilized), on A-cation substitution suggests that the two stabilization mechanisms are in competition in these two materials and many other hybrid-improper ferroelectric phases.	Mar 2021
I11-High Resolution Powder Diffraction	Cation control of cooperative CO2 adsorption in Li-containing mixed cation forms of the flexible zeolite merlinoite Veselina M. Georgieva , Elliott L. Bruce , Ruxandra G. Chitac , Magdalena M. Lozinska , Anna M. Hall , Claire A. Murray , Ronald I. Smith , Alessandro Turrina , Paul A. Wright Chemistry Of Materials 154 DOI: 10.1021/acs.chemmater.0c03773 Diamond Proposal Number(s): [22322] Show Abstract ▼ Abstract: The lithium-exchanged form of a merlinoite zeolite (MER) with Si/Al = 4.2 (unit cell composition Li6.2Al6.2Si25.8O64) possesses a strongly contracted framework when dehydrated (the unit cell volume decreases by 12.9% from the hydrated “wide-pore” form to the dehydrated “narrow-pore” form). It shows cooperative adsorption behavior for CO2, leading to two-step isotherms with the second step at elevated pressure (>2.5 bar at 298 K). Partially exchanging Na and K cations to give single-phase Li,Na- and Li,K-MER materials reduces the pressure of this second adsorption step because the transition from narrow- to wide-pore forms upon CO2 adsorption occurs at lower partial pressures compared to that in Li-MER: partial exchange with Cs does not reduce the pressure of this transition. Exsolution effects are also seen at K cation contents >2.2 per unit cell. The phase transitions proceed via intermediate structures by complex phase behavior rarely seen for zeolitic materials. The strongly distorted narrow-pore structures adopted upon dehydration give one-dimensional channel structures in which the percolation of CO2 through the material requires cation migration from their locations in ste sites. This is slow in Li3.4Cs2.8-MER where Cs cations occupy these critical ste cavities in the channels, causing very slow adsorption kinetics. As the partial pressure of CO2 increases, a threshold pressure is reached where cooperative adsorption and Cs cation migration occur and the wide-pore form results, with a three-dimensionally connected pore system, leading to a sharp increase in uptake. This is far in excess of the increase of unit cell volume because more of the pore space becomes accessible. Strong hysteretic effects occur upon desorption, leading to CO2 encapsulation. CO2 remaining within the material after repeated adsorption/desorption cycles without heated activation improves sorption kinetics and modifies the stepped isotherms.	Feb 2021
I14-Hard X-ray Nanoprobe	Ordered LiNi0.5Mn1.5O4 cathode in bis(fluorosulfonyl)imide-based ionic liquid electrolyte: importance of the cathode–electrolyte interphase Hyeon Jeong Lee , Zachary Brown , Ying Zhao , Jack Fawdon , Weixiao Song , Ji Hoon Lee , Johannes Ihli , Mauro Pasta Chemistry Of Materials DOI: 10.1021/acs.chemmater.0c04014 Diamond Proposal Number(s): [22264] Show Abstract ▼ Abstract: The high-voltage (4.7 V vs Li+/Li) spinel lithium nickel manganese oxide (LiNi0.5Mn1.5O4, LNMO) is a promising candidate for the next generation of lithium-ion batteries due to its high energy density, low cost, and low environmental impact. However, poor cycling performance at high cutoff potentials limits its commercialization. Herein, hollow-structured LNMO is synergistically paired with an ionic liquid electrolyte, 1 M lithium bis(fluorosulfonyl)imide (LiFSI) in N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (Pyr1,3FSI), to achieve stable cycling performance and improve the rate capability. The optimized cathode–electrolyte system exhibits extended cycling performance (>85% capacity retention after 300 cycles) and high rate performance (106.2 mAh g–1 at 5C) even at an elevated temperature of 65 °C. X-ray photoelectron spectroscopy and spatially resolved X-ray fluorescence analyses confirm the formation of a robust, LiF-rich cathode–electrolyte interphase. This study presents a comprehensive design strategy to improve the electrochemical performance of high-voltage cathode materials.	Feb 2021
	Geometric analysis and formability of the cubic A2BX6 vacancy-ordered double perovskite structure Warda Rahim , Anjie Cheng , Chenyang Lyu , Tianyi Shi , Ziheng Wang , David O. Scanlon , Robert G. Palgrave Chemistry Of Materials DOI: 10.1021/acs.chemmater.0c02806 Show Abstract ▼ Abstract: A geometric analysis of the cubic A2BX6 structure commonly formed by metal halides is presented. Using the “hard-sphere” approximation, where the ions are represented by spheres of a fixed radius, we derive four limiting models that each constrain the distances between constituent ions in different ways. We compare the lattice parameters predicted by these four models with experimental data from the Inorganic Crystal Structure Database (ICSD). For the fluorides, the maintenance of the AX bond length at the sum of the A and X radii gives the best approximation of the lattice parameter, leading to structures with widely separated BX6 octahedra. For the heavier halides, a balance between forming an A-site cavity of the correct size and maintaining suitable anion–anion distances determines the lattice parameter. It is found that in many A2BX6 compounds of heavier halides, the neighboring octahedra show very significant anion–anion overlap. We use these models to predict a compound with A-site rattling and use density functional theory (DFT) to confirm this prediction. Finally, we use the geometric models to derive formability criteria for vacancy-ordered double perovskites.	Nov 2020
I15-1-X-ray Pair Distribution Function (XPDF)	La2Ga3O7.5 : A metastable ternary melilite with a super-excess of interstitial oxide ions synthesized by direct crystallization of the melt Jintai Fan , Vincent Sarou-Kanian , Xiaoyan Yang , Maria Diaz-Lopez , Franck Fayon , Xiaojun Kuang , Michael J. Pitcher , Mathieu Allix Chemistry Of Materials DOI: 10.1021/acs.chemmater.0c03441 Show Abstract ▼ Abstract: The La1+xAE1–xGa3O7+x/2 melilite family (AE = Ca, Sr, and Ba and 0 ≤ x ≤ 0.64) demonstrates remarkable oxide ion conductivity due to the ability of its layered tetrahedral [Ga3O7+x/2] network to accommodate and transport interstitial oxide ions (Oint). Compositions of x > 0.65 with very high Oint concentrations (referred to here as “super-excess” compositions) have the potential to support correspondingly high ionic conductivities but have never before been accessed due to the limitations of conventional solid-state ceramic synthesis. Here, we report that fully substituted La2Ga3O7.5 (x = 1) melilite ceramics can be synthesized by direct crystallization of an under-cooled melt, demonstrating that super-excess compositions are accessible under suitable nonequilibrium reaction conditions. La2Ga3O7.5 is stable up to 830 °C and exhibits an ionic conductivity of 0.01 S·cm–1 at 800 °C, 3 orders of magnitude higher than the corresponding x = 0 end-member LaSrGa3O7 and close to the range exhibited by the current best-in-class La1.54Sr0.46Ga3O7.23 (0.1 S·cm–1). It crystallizes in an orthorhombic √2a × √2a × 2c expansion of the parent melilite cell in the space group Ima2 with full long-range ordering of Oint into chains within the [Ga3O7.5] layers. The emergence of this chain-like (1D) ordering within the 2D melilite framework, which appears to be an incipient feature of previously reported partially ordered melilites, is explained in terms of the underlying hexagonal topology of the structure. These results will enable the exploration of extended compositional ranges for the development of new solid oxide ion electrolytes with high concentrations of interstitial oxide charge carriers.	Oct 2020

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User