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Hong Zhang - One of the best experts on this subject based on the ideXlab platform.
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NiO/Ni nanocomposites embedded in 3D porous carbon with high performance for lithium-ion storage
Journal of Materials Science, 2020Co-Authors: Zefang Yang, Zhicheng Li, Pengfei Li, Caiyun Gao, Hong ZhangAbstract:The high energy storage devices such as lithium-ion batteries (LIBs) have recently attracted extensive attention, and massive efforts have been made to synthesize the high-performance electrodes for Li-ion storage. Here, a facile in situ synthesis method was proposed to prepare the NiO/Ni nanocomposites embedded in three-dimensional (3D) porous carbon network (denoted as NiO/Ni⊕C). The Phase Component and microstructure of the NiO/Ni⊕C were detected by using X-ray diffraction, scanning electron microscope and transmission electron microscopy. The NiO/Ni nanocomposites with the particle size of approximately 20–50 nm were uniformly dispersed in the 3D porous carbon matrix. The 3D carbon network is in favor of electrical conductivity, and effectively alleviates the volume effect during lithiation–delithiation processes, and thus help the electrode achieve high electrochemistry performance. The NiO/Ni⊕C electrodes possess a reversible specific capacity of 934 mAh g^−1 at a current density of 300 mA g^−1, and exhibit a superior rate performance with a specific capacity of 505 mAh g^−1 at a current density of 2 A g^−1. The NiO/Ni⊕C electrodes maintained a specific capacity of up to 683 mAh g^−1 even after 1000 cycles at a current density of 1 A g^−1.
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electrical property and temperature sensitivity of nife 2 x sb x o 4 x 0 02 ceramics for negative temperature coefficient thermistors
Journal of Materials Science: Materials in Electronics, 2018Co-Authors: Yuan Zeng, Hong ZhangAbstract:The NiFe2−xSb x O4 (x = 0.0, 0.008, 0.01, 0.015, 0.02) ceramics were prepared by a wet chemical process. The related ceramics were obtained by powders compacting and sintering by conventional ceramic processing. The Phase Component, cationic valence and electrical properties of the prepared ceramics were investigated. The investigation results indicate that NiFe2−xSb x O4 ceramics have a cubic spinel structure and display a typical characteristic of negative temperature coefficient (NTC) of resistivity. The room temperature resistivity of NiFe2−xSb x O4 ceramics can be adjusted from 75597 to 2714 Ω cm by changing the contents of Sb, and the ceramics hold high thermal sensitivity with NTC material constants between 3612 and 5408 K. The investigation of impedance spectra measured at different temperatures revealed that the grain effect and grain-boundary effect contribute simultaneously to the electrical conductivity and NTC effect. Conduction mechanism of NiFe2−xSb x O4 NTC thermistors are proposed to follow the polaron hopping model.
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electrical properties and temperature sensitivity of mo modified mnfe2o4 ceramics for application of ntc thermistors
Journal of Materials Science: Materials in Electronics, 2018Co-Authors: Jia Guo, Hong ZhangAbstract:The Mo modified MnFe2O4 (MnFe2−x Mo x O4, x ≤ 0.05) powders were prepared by using a wet-chemical synthesis method and the related ceramics were obtained by a traditional ceramic sintering technology. The effect of Mo contents on the Phase Component and related electrical properties of the ceramics were investigated. The results show that the prepared ceramics have a spinel-type cubic crystalline structure, and show a typical characteristic of negative temperature coefficient (NTC) of resistivity. The thermal sensitivity constants are around 6100 K over a wide temperature range from 25 to 250 °C. The analysis of impedance spectra reveals that both grain effect and grain boundary effect contribute to the NTC feature. The conduction mechanisms for the ceramics are mainly proposed to be the electron hopping conduction inside the grains and the thermally activated charge carrier transport by overcoming the energy barrier for the grain boundary conduction.
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li fe modified zn 0 3 ni 0 7 o ntc thermistors with adjustable resistivities and temperature sensitivity
Journal of Materials Science: Materials in Electronics, 2018Co-Authors: Xiang Sun, Shiyuan Chen, Hong ZhangAbstract:Li/Fe modified Zn0.3Ni0.7O, (Zn0.3Ni0.7)1−x−y Li x Fe y O (x = 0–0.06, y = 0–0.04), were synthesized by a wet chemical synthesis methods and sintered by the traditional ceramic sintering technology. The Phase Component and related electrical properties of the ceramics were investigated. The analysis of X-ray diffraction indicates that all the prepared ceramics have a cubic crystalline structure. The resistance-temperature feature exhibits a typical effect of negative temperature coefficient (NTC) of resistivity in a temperature range from 25 to 250 °C. The ceramics have room-temperature resistivities ranging from 26.6 Ω cm to 102.8 MΩ cm and thermal-sensitivity constants from 2444 to 8378 K by changing the concentrations of Li and Fe. The complex impedance analysis reveals that both grain effect and grain boundary effect contribute collectively to the NTC feature of the ceramics. The possible conduction models were proposed to combine with electron-hopping conduction and band conduction.
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electrical properties and thermal sensitivity of ti y modified cuo based ceramic thermistors
Frontiers of Materials Science, 2016Co-Authors: Bao Yang, Hong Zhang, Jia Guo, Ya LiuAbstract:The Ti/Y modified CuO-based negative temperature coefficient (NTC) thermistors, Cu0.988-2yY0.008Ti y O (TYCO; y = 0.01, 0.015, 0.03, 0.05 and 0.07), were synthesized through a wet-chemical method followed by a traditional ceramic sintering technology. The related Phase Component and electrical properties were investigated. XRD results show that the TYCO ceramics have a monoclinic structure as that of CuO crystal. The TYCO ceramics can be obtained at the sintering temperature 970°C-990°C, and display the typical NTC characteristic. The NTC thermal-sensitive constants of TYCO thermistors can be adjusted from 1112 to 3700 K by changing the amount of Ti in the TYCO ceramics. The analysis of complex impedance spectra revealed that both the bulk effect and grain boundary effect contribute to the electrical behavior and the NTC effect. Both the band conduction and electron-hopping models are proposed for the conduction mechanisms in the TYCO thermistors.
Lahcene Ouahab - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Studies of Redox-Active Tetrathiafulvalene-Based Complexes: Dysprosium vs. Ytterbium AnaloguesRedox-Active Tetrathiafulvalene-Based Complexes
European Journal of Inorganic Chemistry, 2014Co-Authors: Julie Jung, Tamyris T. Da Cunha, Boris Le Guennic, Fabrice Pointillart, Cynthia L. M. Pereira, Javier Luzon, Stephane Golhen, Olivier Cador, Olivier Maury, Lahcene OuahabAbstract:The two mononuclear complexes [Ln(tta)3(L)]*C6H14 {Ln = DyIII and YbIII} (tta- = 2-thenoyltrifluoroacetonate, L = 2-{1-methylpyridyl-4,5-[4,5-bis(propylthio)tetrathiafulvalenyl]-1H-benzimidazol-2-yl}pyridine) are isostructural. The lanthanide ions adopt a distorted-square-antiprism coordination polyhedron (D4d symmetry). The DyIII compd. behaves like a single-mol. magnet (SMM), whereas no out-of-Phase Component of the magnetic susceptibility is measured for YbIII. The crystal-field splitting of the 2F7/2 and 6H15/2 ground multiplets of YbIII and DyIII, resp., were detd. by means of ab initio calcns. and confirmed by the emission energy lines of the 2F5/2→2F7/2 luminescence spectrum in the case of YbIII. The nature of the MJ ground states indicates that YbIII is not an Ising system, whereas DyIII is. The exptl. and calcd. anisotropy axes for DyIII lie along the most neg. charged direction, whereas those for YbIII lie almost perpendicularly. Finally, the gz values corroborate the uniaxiality of the anisotropy axis for DyIII.
Qidong Wang - One of the best experts on this subject based on the ideXlab platform.
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XRD study of the hydrogenation and dehydrogenation process of the two different Phase Components in a Ti-V-based multiPhase hydrogen storage electrode alloy
Journal of Alloys and Compounds, 2003Co-Authors: Hongge Pan, Yunfeng Zhu, Mingxia Gao, Yongfeng Liu, Yongquan Lei, Qidong WangAbstract:Abstract Hydrogenation and dehydrogenation of two different Phases in a multiPhase Ti–V-based alloy Ti 0.8 Zr 0.2 V 1.867 Mn 0.373 Cr 0.56 Ni 0.7 , namely the C14 Laves Phase with hexagonal structure and the V-based solid solution Phase with body centered cubic (bcc) structure during electrochemical charging and discharging were investigated by X-ray powder diffraction (XRD) analysis. For the alloy investigated, the C14 Laves Phase Component, which had good surface electrochemical activity for decomposing water, was hydrogenated from the very beginning of the charging process and was providing hydrogen to both Phase Components throughout the entire electrochemical charging process. The V-based solid solution Phase, which had no or very low surface electrochemical activity for decomposing water during electrochemical charging, could obtain hydrogen only from its neighboring C14 Laves Phase Component when the hydrogen content of which was high enough to build up an adequate pressure to feed hydrogen to its neighboring Phase Component. The V-based solid solution Phase experienced a Phase change when the hydrogen in it reached a definite level, namely from bcc to body centered tetragonal (bct) structure. Probably due to the high stability of bct hydride Phase of the V-based solid solution Phase, it did not revert back to the initial bcc structure during the electrochemical discharging process conducted in our experiment at the room temperature and atmospheric pressure.
Fabrice Pointillart - One of the best experts on this subject based on the ideXlab platform.
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Field-Induced Dysprosium Single-Molecule Magnet Based on a Redox-Active Fused 1,10-Phenanthroline-Tetrathiafulvalene-1,10-Phenanthroline Bridging Triad
Frontiers in Chemistry, 2018Co-Authors: Bertrand Lefeuvre, Boris Le Guennic, Olivier Cador, Olivier Galangau, Jessica Flores Gonzalez, Vincent Montigaud, Vincent Dorcet, Lahcone Ouahab, Fabrice PointillartAbstract:Tetrathiafulvalene and 1,10-phenanthroline moieties present, respectively remarkable redox-active and complexation activities. In this work, we investigated the coordination reaction between the bis(1,10-phenanthro[5,6-b])tetrathiafulvalene triad (L) and the Dy(hfac)(3)center dot 2H(2)O metallo precursor. The resulting {[DY2(hfac)(6)(L)]center dot CH2Cl2 center dot C6H14}(3) (1) dinuclear complex showed a crystal structure in which the triad L bridged two terminal Dy(hfac)(3) units and the supramolecular co-planar arrangement of the triads is driven by donor-acceptor interactions. The frequency dependence of the out-of-Phase Component of the magnetic susceptibility highlights three distinct maxima under a 2000 Oe static applied magnetic field, a sign that 1 displays a Single-Molecule Magnet (SMM) behavior with multiple magnetic relaxations. Ab initio calculations rationalized the Ising character of the magnetic anisotropy of the Dy-III ions and showed that the main anisotropy axes are perpendicular to the co-planar arrangement of the triads. Single-crystal rotating magnetometry confirms the orientation of the main magnetic axis. Finally combining structural analysis and probability of magnetic relaxation pathways through Quantum Tunneling of the Magnetization (QTM) vs. excited states (Orbach), each Dy-III center has been attributed to one of the three observed magnetic relaxation times. Such coordination compound can be considered as an ideal candidate to perform redox-magnetic switching.
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Magnetic Studies of Redox-Active Tetrathiafulvalene-Based Complexes: Dysprosium vs. Ytterbium AnaloguesRedox-Active Tetrathiafulvalene-Based Complexes
European Journal of Inorganic Chemistry, 2014Co-Authors: Julie Jung, Tamyris T. Da Cunha, Boris Le Guennic, Fabrice Pointillart, Cynthia L. M. Pereira, Javier Luzon, Stephane Golhen, Olivier Cador, Olivier Maury, Lahcene OuahabAbstract:The two mononuclear complexes [Ln(tta)3(L)]*C6H14 {Ln = DyIII and YbIII} (tta- = 2-thenoyltrifluoroacetonate, L = 2-{1-methylpyridyl-4,5-[4,5-bis(propylthio)tetrathiafulvalenyl]-1H-benzimidazol-2-yl}pyridine) are isostructural. The lanthanide ions adopt a distorted-square-antiprism coordination polyhedron (D4d symmetry). The DyIII compd. behaves like a single-mol. magnet (SMM), whereas no out-of-Phase Component of the magnetic susceptibility is measured for YbIII. The crystal-field splitting of the 2F7/2 and 6H15/2 ground multiplets of YbIII and DyIII, resp., were detd. by means of ab initio calcns. and confirmed by the emission energy lines of the 2F5/2→2F7/2 luminescence spectrum in the case of YbIII. The nature of the MJ ground states indicates that YbIII is not an Ising system, whereas DyIII is. The exptl. and calcd. anisotropy axes for DyIII lie along the most neg. charged direction, whereas those for YbIII lie almost perpendicularly. Finally, the gz values corroborate the uniaxiality of the anisotropy axis for DyIII.
Ferenc Zsila - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of heat- and chemical-induced aggregation of various proteins reveals chaperone-like activity of the acute-Phase Component and serine protease inhibitor human α1-antitrypsin
Biochemical and biophysical research communications, 2010Co-Authors: Ferenc ZsilaAbstract:Abstract In vitro chaperone-like activity of the serpin family member and plasma acute-Phase Component human α1-antitrypsin (AAT) has been shown for the first time. Results of light-scattering experiments demonstrated that AAT efficiently inhibits both heat- and chemical-induced aggregation of various test proteins including alcohol dehydrogenase, aldolase, carbonic anhydrase, catalase, citrate synthase, enolase, glutathione S-transferase, l -lactate dehydrogenase, and βL-crystallin. The results suggest that the unique metastable serpin architecture enables dual function, protease inhibiton as well as chaperone activity and highlight the serpin superfamily as a possible source of additional intra- and extracellular chaperones (e.g. α1-antichymotrypsin). The present finding is surprising in the light of the well-known role of mutated forms of AAT and other serpins in the pathogenesis of diseases called serpinopathies that featured with aberrant conformational transitions and consequent self-aggregation of serpin proteins.
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Chaperone-like activity of the acute-Phase Component human serum α1-acid glycoprotein: Inhibition of thermal- and chemical-induced aggregation of various proteins
Bioorganic & medicinal chemistry letters, 2009Co-Authors: Ferenc ZsilaAbstract:Abstract In vitro chaperone-like activity of the acute-Phase Component and plasma drug transporter human α1-acid glycoprotein (AAG) has been shown for the first time. AAG suppressed thermal aggregation of a variety of unrelated enzymatic (e.g., aldolase, catalase, enolase, carbonic anhydrase) and non-enzymatic proteins (β-lactoglobulin, ovotransferrin) and it also prevented dithiothreitol induced aggregation of insulin. The anti-aggregation ability of AAG was abolished/reduced upon drug binding suggesting that protein–protein interactions established between the lipocalin β-barrel fold of AAG and hydrophobic surfaces of the stressed proteins are involved in the chaperone-like activity. The results shed some light on the possible biological function of this enigmatic protein and suggest that besides haptoglobin, clusterin, fibrinogen and α2-macroglobulin AAG can be considered as a novel member of the extracellular molecular chaperones found in human body fluids.