Browsing by Author "Wang, Y"

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    High capacity spherical Li[Li0.24Mn0.55Co0.14Ni0.07]O2 cathode material for lithium ion batteries
    (Elsevier Science BV, 2013-02-21) Wang, Y; Sharma, N; Su, DW; Bishop, D; Ahn, H; Wang, GX
    Li[Li0.24Mn0.55Co0.14Ni0.07]O-2 cathode materials with controlled spherical morphology and particle size in the range of 5-10 mu m were synthesized by a modified co-precipitation method. The crystal structure of Li[Li0.24Mn0.55Co0.14Ni0.07]O-2 was investigated by Rietveld analysis of structural models using X-ray and neutron powder diffraction data, indicating the presence of Li2MnO3 in the final product. Li[Li0.24Mn0.55Co0.14Ni0.07]O-2 shows low initial irreversible capacity loss (47.2 mAh/g), high reversible capacity (264.6 mAh/g), good capacity retention (90.4% over 50 cycles) and satisfactory rate capability when used as the cathode material in lithium ion batteries. X-ray photoelectron spectroscopy analysis of the pristine, charged and discharged electrodes of Li[Li0.24Mn0.55Co0.14Ni0.07]O-2 reveals that the Mn4+/Mn3+ redox couple participates in the delithiation/lithiation process. Overall, the improved electrochemical performance of the Li[Li0.24Mn0.55Co0.14Ni0.07]O-2 electrode can be ascribed to the controlled and specially designed morphology and the composition of the sample that is produced by the co-precipitation method. © 2013, Elsevier Ltd.
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    High-yield synthesis and crystal structure of a green Au30 cluster co-capped by thiolate and sulfide
    (Royal Society of Chemistry, 2016-09-24) Yang, H; Wang, Y; Edwards, AJ; Yana, J; Zheng, N
    A green gold-cluster, Au30S(StBu)18, was successfully prepared in high yield and crystallographically characterized. Each cluster consists of an Au22 core capped by a mixed layer of staple Au-thiolate units, bridging thiolates and a μ3-S2−.© 2014, The Royal Society of Chemistry.
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    Hydrogen-induced microstructure, texture and mechanical property evolutions in a high-pressure torsion processed zirconium alloy
    (Elsevier Ltd., 2012-11-01) Wang, Z; Garbe, U; Li, HJ; Studer, AJ; Harrison, RP; Callaghan, MD; Wang, Y; Liao, XZ
    The gaseous hydriding-induced evolutions of the microstructure, texture and mechanical properties of Zircaloy-4 processed by high-pressure torsion (HPT) were assessed. Much delta-ZrH(1.66) precipitation at 15 atm (21%) incurred significant hardening of vacuum-annealed HPT samples, and pure epsilon-ZrH(2) obtained at 20 atm showed a superior microhardness of 470 HV(0.3) and a low fracture toughness of 0.63 MPa m(1/2). The delta-hydrides presented strong (1 1 1) texture and followed the (0 0 0 1)(alpha-Zr)//{1 1 1}(delta-ZrH1.66) orientation relationship with the alpha-Zr matrix. During hydriding, alpha-Zr recrystallization texture was developed from the initial deformation texture. Copyright © 2012 Acta Materialia Inc.
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    Isochron 26A1/10Be burial dating of Xihoudu: evidence for the earliest human settlement in northern China
    (Elsevier, 2020-12) Shen, G; Wang, Y; Tu, H; Tong, H; Wu, Z; Kuman, K; Fink, D; Granger, DE
    The mainstream school of human evolution posits that Homo erectus was the earliest species to leave Africa at ∼1.85 million years (Ma) ago. Recent discoveries from the Shangchen loess-palaeosol sequence near the Lantian hominid site in northern China, however, show lithic artifacts up to 2.12 Ma, pre-dating the fossil record of H. erectus. Here we apply the recently established isochron 26Al/10Be burial dating, whose reliability has been verified by intercomparison with 40Ar/39Ar dating, to two locations at the Palaeolithic site of Xihoudu ∼100 km east of Shangchen. The results show that the stone tools found within river gravels there are 2.43 ± 0.06 Ma (1σ) old, making them the earliest radio-isotopically dated evidence for human occupation in Eurasia. The new date is supported by relative dating of the associated fauna, by consistent simple burial ages of quartz sand from deep cores, and by agreement between the two isochrons. Although the validity of the Xihoudu artifacts has been previously debated because of marked fluvial abrasion, there is clear evidence of intentional flaking. In particular, in addition to two cores with small amounts of cortex, a number of flakes lack original rock cortex, which indicate multiple and sustained removals that do not occur naturally. The great antiquity of the Xihoudu artifacts renders firm support to an earlier “Out of Africa I” that approaches the emergence of the genus Homo and the Oldowan industry. © 2020 Elsevier Masson SAS.
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    Manipulation of planar oxygen defect arrangements in multifunctional magnèli titanium oxide hybrid systems: from energy conversion to water treatment
    (Royal Society of Chemistry, 2020-10-28) Liu, YC; Yang, J; Liu, Y; Zheng, J; Lee, W; Shi, JJ; Horlyck, J; Xie, JZ; Tay, YY; Tan, TT; Yu, DH; Mole, RA; McIntyre, GJ; Zhang, CY; Toe, CY; Waite, TD; Scott, J; Wang, Y; Wu, T; Han, SH; Li, S
    An extremely close relationship exists between energy usage and water supply with a tremendous amount of energy being consumed to process water for drinking and other purposes. The current energy crisis and inefficient water management place enormous stress on the sustainability of our society and environment. As such, the development of high-efficiency, cost-effective, and environmentally friendly materials which possess co-existing functionalities for applications ranging from energy capture to water treatment in one material, provides an opportunity to achieve sustainable development. As multifunctional materials, the layer-structured Magnèli titanium oxides with stoichiometry of TinO2n−1 (n ≥ 2) have been extensively studied in view of their potential for photocatalytic, thermoelectric and photothermal applications over the past few years. This group of materials occurs naturally as layered structures with planar oxygen defects, however, understanding of the correlation between the planar arrangements of the oxygen defects and various energy-related properties remains limited. Here, we demonstrate how the formation of layer structured TinO2n−1 with various planar oxygen defect arrangements correlates with the changes of their physical and chemical properties. The experimental results from inelastic neutron scattering analysis and electrical characterizations provide evidence that the planar oxygen defects are responsible for phonon scattering and exert a strong influence on their electrical conductivities. Manipulating these planar defects allows interconversion between different phases, which changes the interplay between electronic and phononic sub-systems. These manipulations potentially enable optimization of the corresponding physical properties of these materials such that they are rendered suitable for applications that require co-operative multifunctionality. More specifically, the experimental results demonstrate that the valence band positions and the onset potentials in the materials are raised, further enhancing their ability for catalysis of electrochemical reactions. This work also demonstrates the combinational effects of the thermoelectric and photothermal properties of these materials on their photocatalytic and electrochemical performance thereby providing a novel means of controlling the multi-response functionality of these materials for a variety of applications in different environments. © The Royal Society of Chemistry 2020
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    Martensitic phase transformation and deformation behavior of Fe–Mn–C–Al twinning-induced plasticity steel during high-pressure torsion
    (Wiley Online Library, 2014-02-05) Yan, K; Bhattacharyya, D; Lian, Q; Kabra, S; Kawasaki, M; Carr, DG; Callaghan, MD; Avdeev, M; Li, HJ; Wang, Y; Liao, XZ; Langdon, TG; Liss, KD; Dippenaar, RJ
    The transformation between the face centered cubic austenitic and hexagonal close-packed martensitic phases during high-pressure torsion processing was observed in a Fe–Mn–C–Al twinning-induced plasticity steel. This phase transformation was not found in the same material processed by unidirectional compressive and tensile deformation. Initiated by the high-pressure loading, the martensite phase initially increased with torsional strain but diminished subsequently. Texture evolution of the austenitic phase was compared with the ideal texture distribution of face-centered cubic materials after shear deformation.© 2014, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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    Mass spectrometry and Monte Carlo Method mapping of nanoparticle ligand shell morphology
    (Springer Nature, 2018-10-26) Luo, Z; Shao, YF; Darwish, TA; Wang, Y; Hou, J; Stellacci, F
    Janus, patchy, stripe-like, or random arrangements of molecules within the ligand shell of nanoparticles affect many properties. Among all existing ligand shell morphology characterization methods, the one based on mass spectroscopy is arguably the simplest. Its greatest limitation is that the results are qualitative. Here, we use a tailor-made Monte Carlo type program that fits the whole MALDI spectrum and generates a 3D model of the ligand shell. Quantitative description of the ligand shell in terms of nearest neighbor distribution and characteristic length scale can be readily extracted by the model, and are compared with the results of other characterization methods. A parameter related to the intermolecular interaction is extracted when this method is combined with NMR. This approach could become the routine method to characterize the ligand shell morphology of many nanoparticles and we provide an open access program to facilitate its use. © The Authors - Creative Commons Attribution 4.0
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    Microstructural evolution during gaseous hydrogen charging of Zircaloy-4 processed by high-pressure torsion: a comparative study
    (Elsevier B.V., 2012-02-01) Wang, ZY; Li, HJ; Garbe, U; Callaghan, MD; Wang, Y; Liao, XZ
    The original and high-pressure torsion (HPT) processed Zircaloy-4 materials were hydrided using gaseous hydrogen charging at different hydrogen pressures (10, 15 and 20 atm). The phase and microstructural evolutions of the samples during hydriding were characterized. It showed that when hydriding at the identical conditions, more hydrides tended to form in the HPT samples compared to that of the original ones. At a hydrogen pressure of 20 atm, the HPT sample was completely converted to epsilon-ZrH2 while some delta-ZrH1.66 hydrides (volume fraction similar to 5.73%) were present in the material without HPT preprocessing. The HPT samples exhibited high potential for the hydride precipitation, and the large concentration of lattice defects induced by HPT was considered to be responsible for this enhanced susceptibility. © 2011 Elsevier B.V.
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    On the atomic anisotropy of thermal expansion in bulk metallic glass
    (Wiley-Blackwell, 2011-09-01) Qu, DD; Liss, KD; Yan, K; Reid, M; Almer, JD; Wang, Y; Liao, XZ; Shen, J
    Glass transition temperature and plastic yield strength are known to be correlated in metallic glasses. We have observed by in situ synchrotron high energy X-ray diffraction anisotropy of the thermal expansion behavior in the nearest neighbor and second nearest neighbor atomic distances in the building blocks of Zr-Cu-Ni-Al based bulk metallic glass, leading inevitably to shear. Mechanical yielding of the latter on the atomic scale leads to the glass transition and the increase of the free volume. These experimental results uncover the mechanism, how glass transition and yield strength are linked. © 2011, Wiley-Blackwell.
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    P2-Na0.6[Cr0.6Ti0.4]O2 cation-disordered electrode for high-rate symmetric rechargeable sodium-ion batteries
    (Springer Nature, 2015-04-24) Wang, Y; Xiao, R; Hu, YS; Avdeev, M; Chen, L
    Most P2-type layered oxides exhibit Na+/vacancy-ordered superstructures because of strong Na+–Na+ interaction in the alkali metal layer and charge ordering in the transition metal layer. These superstructures evidenced by voltage plateaus in the electrochemical curves limit the Na+ ion transport kinetics and cycle performance in rechargeable batteries. Here we show that such Na+/vacancy ordering can be avoided by choosing the transition metal ions with similar ionic radii and different redox potentials, for example, Cr3+ and Ti4+. The designed P2-Na0.6[Cr0.6Ti0.4]O2 is completely Na+/vacancy-disordered at any sodium content and displays excellent rate capability and long cycle life. A symmetric sodium-ion battery using the same P2-Na0.6[Cr0.6Ti0.4]O2 electrode delivers 75% of the initial capacity at 12C rate. Our contribution demonstrates that the approach of preventing Na+/vacancy ordering by breaking charge ordering in the transition metal layer opens a simple way to design disordered electrode materials with high power density and long cycle life. Copyright © 2015, The Author(s)
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    Structural origins for the high plasticity of a Zr-Cu-Ni-Al bulk metallic glass
    (Pergamon-Elsevier Science Ltd, 2012-09-11) Qu, DD; Liss, KD; Sun, YJ; Reid, M; Almer, JD; Yan, K; Wang, Y; Liao, XZ; Shen, J
    The structural origins for the high plasticity of a Zr(53)Cu(18.7)Ni(12)Al(16.3) (at.%) bulk metallic glass are explored. Under plastic flow conditions, in situ synchrotron high-energy X-ray diffraction reveals that the atomic strain saturates to the closest packing in the longitudinal direction of the applied load while atoms yield in the transverse plane. Scanning electron microscopy investigation reveals that global plasticity benefits from abundant shear band multiplication and interactions. Atomic level flows are seen to accompany profuse shear bands. The plasticity enhancement of this metallic glass benefits from such atomic level flows. Atomic level flow facilitates the activation of shear transformation zones that further self-assemble to promote shear band multiplication. On the other hand, it also mitigates the shear band propagation that prevents catastrophic shear band extension. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. © 2012, Elsevier Ltd.
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    Thermal batteries based on inverse barocaloric effects
    (Science Advances, 2023-02) Zhang, Z; Li, K; Lin, SC; Song, R; Yu, DH; Wang, Y; Wang, JF; Kawaguchi, S; Zhang, Z; Yu, C; Li, X; Chen, J; He, L; Mole, RA; Yuan, B; Ren, QY; Qian, K; Cai, Z; Yu, J; Wang, M; Zhao, C; Tong, X; Zhang, Z; Li, B
    To harvest and reuse low-temperature waste heat, we propose and realize an emergent concept-barocaloric thermal batteries based on the large inverse barocaloric effect of ammonium thiocyanate (NH4SCN). Thermal charging is initialized upon pressurization through an order-to-disorder phase transition, and the discharging of 43 J g-1 takes place at depressurization, which is 11 times more than the input mechanical energy. The thermodynamic equilibrium nature of the pressure-restrained heat-carrying phase guarantees stable long-duration storage. The barocaloric thermal batteries reinforced by their solid microscopic mechanism are expected to substantially advance the ability to take advantage of waste heat. Copyright © 2023 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).