Browsing by Author "Sale, M"
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- Item3DBVSMAPPER : a program for automatically generating bond-valence sum landscapes. Corrigendum(International Union of Crystallography, 2017-12-01) Sale, M; Avdeev, MAn equation in the article by Sale & Avdeev [J. Appl. Cryst. (2012), 45, 1054–1056] is corrected. © International Union of Crystallography.
- Item3DBVSMAPPER: a program for automatically generating bond-valence sum landscapes(International Union of Crystallography, 2012-10-01) Sale, M; Avdeev, MA computer program, 3DBVSMAPPER, was developed to generate bond-valence sum maps and bond-valence energy landscapes with minimal user intervention. The program is designed to calculate the spatial distributions of bond-valence values on three-dimensional grids, and to identify infinitely connected isosurfaces in these spatial distributions for a given bond-valence mismatch or energy threshold and extract their volume and surface area characteristics. It is implemented in the Perl scripting language embedded in Accelrys Materials Studio and has the capacity to process automatically an unlimited number of materials using crystallographic information files as input. © International Union of Crystallography
- ItemCrystal and magnetic structures of melilite-type Ba2MnSi2O7(American Chemical Society, 2019-03-06) Sale, M; Xia, Q; Avdeev, M; Ling, CDMelilite-type Ba2MnSi2O7 was synthesized by a standard powder solid-state reaction route, and its magnetic properties were studied at low temperature. The magnetic structure was found to be C-type pointing along the c axis from neutron powder diffraction, which is different from the G-type ordering previously reported in all other 2-2-4-2 melilites with manganese as the B′-site transition metal. Ab initio (density functional theory) and magnetic dipole–dipole calculations were used to understand the magnetic structure by determining the spin supersuperexchange parameters as well as the relative influence of spin–orbit coupling and the magnetic dipole–dipole interactions. © 2019 American Chemical Society
- ItemCrystal structure and monoclinic distortion of glaserite-type Ba3MnSi2O8(Elsevier, 2018-10-01) Avdeev, M; Xia, Q; Sale, M; Allison, MC; Ling, CDCrystal structure and magnetic properties of glaserite-type Ba3MnSi2O8 were investigated using variable temperature neutron powder diffraction and magnetometry. At room temperature the composition is hexagonal and the crystal structure is best described by the P-3m1 space group (a~ 5.7 Å, c~ 7.3 Å) with the apical oxygen atom modelled on a split site. On cooling below ~ 250 K the structure undergoes a phase transition into a monoclinic C2/c form (√3ahex, ahex, 2chex, β~ 90°). Analysing diffraction data in terms of symmetry-adapted distortion modes suggests that the transition is primarily driven by increasing in-plane displacements of O1, which in turn results in the coupled tilting of [SiO4] and [MnO6] octahedra and in-plane displacements of Ba1 atoms. Magnetic susceptibility measurements and neutron powder diffraction data show no evidence for long-range magnetic ordering down to 1.6 K, although the development of magnetic diffuse scattering suggests that a magnetic transition may take place at lower temperature. Crown Copyright © 2018 Published by Elsevier Inc.
- ItemElucidation of the high-voltage phase in the layered sodium ion battery cathode material P3–Na0.5Ni0.25Mn0.75O2(Royal Society of Chemistry, 2020-09-30) Liu, JT; Didier, C; Sale, M; Sharma, N; Guo, ZP; Peterson, VK; Ling, CDThe P3-type layered oxide Na0.5Ni0.25Mn0.75O2 is a promising manganese-rich positive electrode (cathode) material for sodium ion batteries, with a high working voltage of 4.2–2.5 V vs. Na+/Na and a high capacity of over 130 mA h g−1 when cycled at 10 mA g−1. However, its structural evolution during battery cycling – specifically, the nature of the high-voltage phase above 4 V – has never been fully understood, which has hindered efforts to rationally modify and improve its performance. In this work we use in situ neutron diffraction to show that the phase above 4 V is a modification of the intermediate O3 phase from which all sodium has been removed, and which consequently has a dramatically shorter interlayer distance. We label this fully Na-depleted phase O3s, such that the phase evolution with increasing voltage is P3 → O3 → O3s. Having elucidated its structure, we used first-principles calculations of the electronic structure as a function of sodium content to show that reversible oxygen redox plays a key role in the electrochemical activity of this O3s phase above 4 V. We also calculated the energies of oxygen/transition metal vacancies and found that the O3s phase should be relatively stable against their formation. The results will guide future research aimed at understanding and stabilizing the O3s phase, in order to improve the performance and cycling stability of this material in sodium ion batteries. © The Royal Society of Chemistry 2020
- ItemExperimental and computational study of the magnetic properties of ZrMn2−xCoxGe4O12(Royal Society of Chemistry, 2017-05-15) Xu, D; Sale, M; Avdeev, M; Ling, CD; Battle, PDPolycrystalline samples in the solid solution ZrMn2−xCoxGe4O12 (x = 0.0, 0.5, 1.0, 1.5 and 2.0) have been prepared using the ceramic method and characterised by a combination of magnetometry, X-ray diffraction and neutron diffraction. They all adopt the space group P4/nbm with a ∼ 9.60, c ∼ 4.82 Å and show long-range magnetic order with transition temperatures, TC, in the range 2 ≤ TC/K ≤ 10. The underlying magnetic structure is the same in each case but the ordered spins lie along [001] when x = 0.0 and in the (001) plane for all other compositions. In all cases the magnetically-ordered phase is a weak ferromagnet although the magnitude of the spontaneous magnetisation and the strength of the coercive field are composition-dependent. The magnetic structure can be rationalized by considering the strengths of the interactions along the distinct M–O–Ge–O–M superexchange pathways in the crystal and the observed magnetic structure is entirely consistent with the predictions of ab initio calculations. © The Royal Society of Chemistry 2017
- ItemIn situ neutron diffraction study on layered oxides Na0.5Ni0.25Mn0.75O2(Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Liu, J; Didier, C; Sale, M; Sharma, N; Guo, ZP; Peterson, VK; Ling, CDLayered oxides based on first-row transition metals dominate cathode materials for commercial batteries and remain highly interesting as well as challenging in their structural study during electrochemical reactions. Neutron diffraction is a powerful method to obtain periodic structural information complementary to that obtained by X-ray diffraction. Although inferior to X-ray diffraction in signal resolution, neutron diffraction reveals more reliable structural evolution as the whole bulk of materials are fluxed with neutron beam. Na0.5Ni0.25Mn0.75O2 is a potential sodium ion battery cathode due to its high operating voltage 3.2 V vs Na+/Na and high capacity 130 mAh/g. Its stoichiometry is designed to only utilize the redox couple Ni4+/Ni2+ to avoid the unstable redox couple Mn4+/Mn3+. The high voltage phase for this material has been under debate. The fact that sodium-containing layered oxides are highly hydroscopic, especially at low sodium content, makes it hard to study the final phase ex situ. In the work presented here, we have pushed the signal resolution of in situ neutron diffraction to the limit by loading the optimized material mass at the positive side and the corresponding amount of amorphous hard carbon at the negative side of a pouch cell. The result is the first robust proof of the reversible structural evolution from P3, O3 to O3s on charging and back to O3, P3 on discharging. © 2020 The authors.
- ItemLithium rich and deficient effects in LixCoPO4 (x=0.90, 0.95, 1, 1.05) as cathode material for lithium-ion batteries(Elsevier, 2013-01-15) Xu, J; Chou, SL; Avdeev, M; Sale, M; Liu, HK; Dou, SXA series of LixCoPO4 (x = 0.90, 0.95, 1, 1.05) compounds with different lithium content in the starting compositions were prepared by the sol–gel method. The phase identification was carried out by X-ray diffraction and neutron diffraction. The structure, atom positions, and occupancies were characterized by neutron diffraction. The morphology of LixCoPO4 (x = 0.90, 0.95, 1, 1.05) was examined by field emission scanning electron microscopy. Electrochemical analysis indicated that Li0.95CoPO4 presented the highest discharge capacity at various current densities among all the different x value compounds. The Li0.95CoPO4 showed better cycling stability and coulombic efficiency in the room temperature ionic liquid electrolyte ([C3mpyr][NTf2] containing 1 M LiNTf2) at various current densities in the voltage range of 3.5–5.0 V than in the conventional electrolyte (1 M LiPF6 in ethylene carbonate:diethyl carbonate).© 2012, Elsevier Ltd.
- ItemMagnetic structure and properties of centrosymmetric twisted-melilite K2CoP2O7(Royal Society of Chemistry, 2017-04-24) Sale, M; Avdeev, M; Mohamed, Z; Ling, CD; Barpanda, PTwisted-melilite dipotassium cobalt pyrophosphate (K2CoP2O7, P42/mnm, #136), originally reported by Gabelica-Robert (1981), was synthesized in powder form by a standard solid-state reaction route. The magnetic properties of the material were studied by magnetometry and its magnetic structure determined using neutron powder diffraction for the first time. Below TN = 11 K, the material adopts a G-type antiferromagnetic structure with moments aligned in the ab-plane (magnetic space group Pn′nm, #58.3.473). Ab initio calculations were performed to examine the isotropic magnetic spin exchange parameters as well as the preferred direction of magnetic moments due to spin–orbit coupling. The relationship between crystal structure geometry and the strength of the magnetic interactions was examined and compared to those of melilite-type Sr2CoGe2O7. © The Royal Society of Chemistry 2017
- ItemMagnetic structure of melilite-related centrosymmetric K_2CoP_2O_7: neutron diffraction and DFT study(Asia-Oceania Neutron Scattering Association, 2015-07-23) Sale, M; Avdeev, M; Ling, CD; Barpanda, PA great number of X_2(ZT_2)O_7 compositions with large X=Ln, Ca-Ba, Na, K and small Z and T=Be,Al,Si,Ga,Ge,P,V adopt the melilite crystal structure type. The structure is built of tetrahedral layers of five-member rings and X is located in the interlayer space. Typically, the materials crystallize in the non-centrosymmetric P-42_1m space group. The compositions with magnetic ions (e.g. Z=Mn"2"+,Fe"2"+,Co"2"+,Cu"2"+) are very interesting systems from the magnetic structure point of view due to the 2D character of the structure and lack of inversion center. Depending on chemistry and geometry of a particular composition, a variety of magnetic structures were reported, from simple 3D antiferromagnets to 2D spirals and multiferroics. During our investigations of melilite-type materials a K_2CoP_2O_7 composition was prepared and its magnetic property and structure characterized. The material is built of melilite-type tetrahedral layers but crystallizes in centro-symmetric P4/mnm space group. The magnetic structure has been determined using neutron powder diffraction on the Echidna diffractometer (ANSTO) and further explored with DFT. The results will be presented and discussed in the context of the broad melilite structural family.
- ItemNeutron scattering study of ionic diffusion in Cu–Se superionic compounds(Elsevier Science BV, 2012-10-04) Danilkin, SA; Avdeev, M; Sale, M; Sakuma, TPaper reports the results of the neutron scattering study of crystal structure and diffusion of Cu2 − δSe compounds in superionic α-phase. We found that the crystallographic model with Cu atoms in the 8c (0.25, 0.25, 0.25) and 32f (x, x, x) (x = 0.33–0.39) sites in fluorite lattice provides the best description of the average structure. The quasi-elastic neutron scattering data reveal the decrease of the self-diffusion coefficient with the deviation from the stoichiometry due to the longer residence time of Cu atoms between diffusion hops. Combination of neutron diffraction, quasi-elastic scattering experimental data with the Bond-Valence Method simulations strongly suggests that the Cu atoms diffuse between the nearest 8c sites through the 32f sites. © 2012, Elsevier Ltd.
- ItemRapid lithium insertion and location of mobile lithium in the defect perovskite Li0.18Sr0.66Ti0.5Nb0.5O3(Wiley-V C H Verlag GMBH, 2012-06-18) Brant, WR; Schmid, S; Kuhn, A; Hester, JR; Avdeev, M; Sale, M; Gu, QFFast and fancy: Lithium that was originally disordered within the structure of the perovskite Li0.18Sr0.66Ti0.5Nb0.5O3 can be induced into ordering within the yellow region of the unit cell by low temperatures and treatment with n-butyl-lithium. The fast kinetics of lithium insertion, in connection with a color change, make this nontoxic, air-stable material a suitable candidate for use in electrochromic systems or lithium-storage batteries. © 2012, Wiley-VCH Verlag GmbH & Co. KGaA
- ItemScreening of the alkali-metal ion containing materials from the Inorganic Crystal Structure Database (ICSD) for high ionic conductivity pathways using the bond valence method(Elsevier Science BV, 2012-10-04) Avdeev, M; Sale, M; Adams, S; Rao, RPHigh ionic conductivity is one of the key characteristics of electrolytes and electrode materials directly affecting performance of electrochemical devices in which they are used. In the case of inorganic crystalline solid electrolytes and insertion cathodes the topology and geometry of crystal structure essentially defines ionic conductivity and charge–discharge rates. We employed the bond valence method to identify materials with crystal structures featuring infinite networks of pathways of suitable size that is a prerequisite for fast ion transport. Taking advantage of the method low computational cost, we carried out exhaustive analysis of similar to 13,000 entries of the Inorganic Crystal Structure Database and ranked the materials based on the fraction of crystal structure space with low bond-valence mismatch. The results may be used as a guide for further theoretical and experimental studies of promising compositions. © 2012, Elsevier Ltd.
- ItemSelective interstitial hydration explains anomalous structural distortions and ionic conductivity in 6H-Ba4Ta2O9·1/2H2O(American Chemical Society, 2023-04-11) Marlton, FP; Brown, AJ; Sale, M; Maljuk, A; Büchner, B; Lewis, W; Luck, I; Wood, ML; Mole, RA; Ling, CDThe mixed ionic-electronic conductor 6H-Ba4Ta2O9 undergoes an unconventional symmetry-lowering lattice distortion when cooled below 1100 K in the presence of atmospheric water. This temperature corresponds to the onset of hydration, which reaches a maximum value for 6H-Ba4Ta2O9·1/2H2O below ∼500 K. We use a combination of diffraction, ab initio calculations, and spectroscopy to show that both processes are intimately linked. The presence of very large Ba2+ cations in octahedral interstitial sites (B sites of its hexagonal perovskite-type structure) forces the adjacent vacant octahedral interstitial sites also to expand, making room for them to incorporate hydration species with a total stoichiometric H2O in constrained and highly acidic environments, where they show structural and dynamic characteristics intermediate between those of covalent water molecules and discrete protons and hydroxide ions. This in turn destabilizes the structure so that it distorts on cooling in a way that cannot be explained by conventional symmetry-lowering mechanisms. The resulting synergistic hydration-distortion mechanism is, to the best of our knowledge, unique to close-packed ionic compounds. © 2023 American Chemical Society.