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91.
Prof. Nam‐Soon Choi Dr. Zonghai Chen Dr. Stefan A. Freunberger Dr. Xiulei Ji Prof. Yang‐Kook Sun Prof. Khalil Amine Prof. Gleb Yushin Prof. Linda F. Nazar Prof. Jaephil Cho Prof. Peter G. Bruce 《Angewandte Chemie (International ed. in English)》2012,51(40):9994-10024
Energy‐storage technologies, including electrical double‐layer capacitors and rechargeable batteries, have attracted significant attention for applications in portable electronic devices, electric vehicles, bulk electricity storage at power stations, and “load leveling” of renewable sources, such as solar energy and wind power. Transforming lithium batteries and electric double‐layer capacitors requires a step change in the science underpinning these devices, including the discovery of new materials, new electrochemistry, and an increased understanding of the processes on which the devices depend. The Review will consider some of the current scientific issues underpinning lithium batteries and electric double‐layer capacitors. 相似文献
92.
Stevens R Dodd JL Kresch MG Yazami R Fultz B Ellis B Nazar LF 《The journal of physical chemistry. B》2006,110(45):22732-22735
The lithium-storage material Li(0.6)FePO(4) was studied by inelastic neutron scattering and differential scanning calorimetry. Li(0.6)FePO(4) undergoes a transformation from a two-phase mixture (heterosite and triphylite) to a disordered solid-solution at 200 degrees C. Phonon densities of states (DOS) obtained from the inelastic neutron scattering were similar for the two-phase sample measured at 180 degrees C and the disordered sample measured at 220 degrees C. The vibrational entropy of transformation is 1.8 +/-0.9 J/(K mol), which is smaller than the configurational entropy difference of approximately 3.1 J/(K mol). The measured enthalpy of the disordering transition was estimated as 2.5 kJ/mol. The phonon data show a small change in lattice dynamics upon disordering. 相似文献
93.
Muhammad Faizan Nazar 《Journal of Dispersion Science and Technology》2013,34(5):596-605
Ultraviolet (UV)-visible behavior of 3,4-dihydroxy-9,10-dioxo-2-anthracenesulfonic acid sodium salt (ARS) has been studied at pH 4.0, aqueous medium, and at pH 10.0. The effects of cetyl trimethylammoniumbromide (CTAB) on the UV-visible spectra of ARS have been evaluated qualitatively as well as quantitatively in the different concentration regions of CTAB. The shift in the UV-visible spectrum of ARS, due to CTAB, at its low concentration is comparable to the shift shown by the same at pH 10.0. In acidic and basic pH, effect of CTAB is significantly lowered on the UV-visible spectra than ARS in the purely aqueous medium. In aqueous and basic medium, lower values of partition and binding constant are obtained compared to the one obtained in acidic medium. Conductivity studies show that increasing dye concentrations have no effect on its partitioning behavior nevertheless critical micelle concentration of CTAB is lowered. 相似文献
94.
CdTe thin films were prepared onto water-white glass substrates by the close spaced sublimation technique. The films annealed right after the deposition were then immersed in copper nitrate solution for different periods of time. These films were again annealed at 500 oC for 1 h to ensure the diffusion of copper in the films. The samples were characterized by X-ray diffraction and scanning electron microscopy. The electron microprobe analyzer showed an increase of copper-content in composition. The dc electrical conductivity showed a credible increase with increasing copper-content in the films. With the increase of copper-content, the hole mobility increased systematically. The optical parameters were deduced by fitting the optical transmittance in the wavelength range 300–2500 nm. 相似文献
95.
Halland N Nazaré M Alonso J R'kyek O Lindenschmidt A 《Chemical communications (Cambridge, England)》2011,47(3):1042-1044
A versatile and efficient palladium catalyzed domino reaction leading to a broad range of substituted 1-aminoindoles has been developed. The title compounds were prepared from 2-halo-phenylacetylenes and simple hydrazines in good to excellent yields in just a few hours under mild conditions. 相似文献
96.
Davis LJ Heinmaa I Ellis BL Nazar LF Goward GR 《Physical chemistry chemical physics : PCCP》2011,13(11):5171-5177
Here we report the observation of electron delocalization in nano-dimension xLiFePO(4):(1 - x)FePO(4) (x = 0.5) using high temperature, static, (31)P solid state NMR. The (31)P paramagnetic shift in this material shows extreme sensitivity to the oxidation state of the Fe center. At room temperature two distinct (31)P resonances arising from FePO(4) and LiFePO(4) are observed at 5800 ppm and 3800 ppm, respectively. At temperatures near 400 °C these resonances coalesce into a single narrowed peak centered around 3200 ppm caused by the averaging of the electronic environments at the phosphate centers, resulting from the delocalization of the electrons among the iron centers. (7)Li MAS NMR spectra of nanometre sized xLiFePO(4):(1 - x)FePO(4) (x = 0.5) particles at ambient temperature reveal evidence of Li residing at the phase interface between the LiFePO(4) and FePO(4) domains. Moreover, a new broad resonance is resolved at 65 ppm, and is attributed to Li adjacent to the anti-site Fe defect. This information is considered in light of the (7)Li MAS spectrum of LiMnPO(4), which despite being iso-structural with LiFePO(4) yields a remarkably different (7)Li MAS spectrum due to the different electronic states of the paramagnetic centers. For LiMnPO(4) the higher (7)Li MAS paramagnetic shift (65 ppm) and narrowed isotropic resonance (FWHM ≈ 500 Hz) is attributed to an additional unpaired electron in the t(2g) orbital as compared to LiFePO(4) which has δ(iso) = -11 ppm and a FWHM = 9500 Hz. Only the delithiated phase FePO(4) is iso-electronic and iso-structural with LiMnPO(4). This similarity is readily observed in the (7)Li MAS spectrum of xLiFePO(4):(1 - x)FePO(4) (x = 0.5) where Li sitting near Fe in the 3+ oxidation state takes on spectral features reminiscent of LiMnPO(4). Overall, these spectral features allow for better understanding of the chemical and electrochemical (de)lithiation mechanisms of LiFePO(4) and the Li-environments generated upon cycling. 相似文献
97.
He G Herbst JF Ramesh TN Pinkerton FE Meyer MS Nazar L 《Physical chemistry chemical physics : PCCP》2011,13(19):8889-8893
The hydrogen storage properties of Li(7)VN(4) and Li(7)MnN(4) were investigated both by experiment and by density functional theory calculations. Li(7)VN(4) did not sorb hydrogen under our experimental conditions. Li(7)MnN(4) was observed to sorb 7 hydrogen atoms through the formation of LiH, Mn(4)N, and ammonia gas. An applied pressurized mixture of H(2)/Ar and H(2)/N(2) gases was helpful to mitigate the release of NH(3) but could not prevent its formation. The introduction of N(2) also caused weight gain of the sample by re-nitriding the absorbed products LiH and Mn(4)N, which correlated with the presence of Li(2)NH, LiNH(2), and Mn(2)N detected by X-ray diffraction. While our observed results for Li(7)VN(4) and Li(7)MnN(4) differ in detail, they are in overall qualitative agreement with our theoretical work, which strongly suggests that both compounds are unlikely to form quaternary hydrides. 相似文献
98.
The unsteady laminar flow of an incompressible micropolar fluid over a stretching sheet is investigated. The unsteadiness
in the flow and temperature fields is caused by the time-dependence of the stretching velocity and the surface temperature.
Effects of the unsteadiness parameter, material parameter and Prandtl number on the flow and heat transfer characteristics
are thoroughly examined. 相似文献
99.
Fadzilah Md. Ali Roslinda Nazar Norihan Md. Arifin Ioan Pop 《Heat and Mass Transfer》2011,47(2):155-162
In this paper, the problem of steady magnetohydrodynamic boundary layer flow and heat transfer of a viscous and electrically
conducting fluid over a stretching sheet is studied. The effect of the induced magnetic field is taken into account. The transformed
ordinary differential equations are solved numerically using the finite-difference scheme known as the Keller-box method.
Numerical results are obtained for various values of the magnetic parameter, the reciprocal magnetic Prandtl number and the
Prandtl number. The effects of these parameters on the flow and heat transfer characteristics are determined and discussed
in detail. When the magnetic field is absent, the closed analytical results for the skin friction are compared with the exact
numerical results. Also the numerical results for the heat flux from the stretching surface are compared with the results
reported by other authors when the magnetic field is absent. It is found that very good agreement exists. 相似文献
100.
S. K. Godunov Yu. D. Manuzina M. A. Nazar’eva 《Computational Mathematics and Mathematical Physics》2011,51(1):88-95
Convergence of the approximate solution of fluid dynamics problems obtained using Godunov’s scheme to the discontinuous solution
is investigated. 相似文献