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171.
Several different metal oxides based anode systems are compared to give insight into their cycling behaviour. The simple electrochemical
model for these systems does not usefully predict the ability for a battery to cycle. Pb and Zn oxides cycle less well than
Sn oxides, and show more initial crystallinity. SnF2 and PbF2 cycle less well than SnO and PbO. Cubic SnP2O7 cycles better than the layered polymorph. The nature and structure of the supporting matrix is therefore important in the
ability of the tin oxides to cycle. Any material with observable crystallinity in first cycle, will not cycle well.
Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16–22, 2001. 相似文献
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A numerical solution is presented for the friction factorReynolds number relation for a fluid which is Newtonian at low shear rates, power law at high shear rates with a transition region at intermediate shear rates. The solution makes possible the conservation of similitude when designing duct systems for such fluids since both Reynolds numbers and shear rates are considered. 相似文献
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Cameron PA Gibson VC Irvine DJ 《Angewandte Chemie (International ed. in English)》2000,39(12):2141-2144
177.
Irvine DR Martin RL Klimkeit E Smith R 《The Journal of the Acoustical Society of America》2000,108(6):2964-2968
On a variety of visual tasks, improvement in perceptual discrimination with practice (perceptual learning) has been found to be specific to features of the training stimulus, including retinal location. This specificity has been interpreted as evidence that the learning reflects changes in neuronal tuning at relatively early processing stages. The aim of the present study was to examine the frequency specificity of human auditory perceptual learning in a frequency discrimination task. Difference limens for frequency (DLFs) were determined at 5 and 8 kHz, using a three-alternative forced choice method, for two groups of eight subjects before and after extensive training at one or the other frequency. Both groups showed substantial improvement at the training frequency, and much of this improvement generalized to the nontrained frequency. However, a small but statistically significant component of the improvement was specific to the training frequency. Whether this specificity reflects changes in neural frequency tuning or attentional changes remains unclear. 相似文献
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179.
W. Preis J. WaldhäuslA. Egger W. SitteE. de Carvalho J.T.S. Irvine 《Solid State Ionics》2011,192(1):148-152
The electrical properties of bulk and grain boundaries of scandia-stabilized zirconia co-doped with yttria and ceria have been determined as a function of temperature (300 < T/°C < 700) and oxygen partial pressure [10− 24 ≤ p(O2)/bar ≤ 1, T = 700 °C] by application of impedance spectroscopy. The yttria and ceria contents of CexY0.2 − xSc0.6Zr3.2O8 − δ (0 ≤ x ≤ 0.2) have been varied systematically. Homogeneous samples have been prepared by means of a sol-gel (glycine-nitrate) combustion process. The ionic conductivity in air is almost independent of composition with typical values around 0.03-0.04 S cm− 1 for the bulk at 700 °C. A significant decrease of the ionic conductivities of bulk and grain boundaries is found for samples co-doped with ceria at low oxygen partial pressures [p(O2) < 10− 15 bar, T = 700 °C]. Activation energies for the ionic transport in oxidizing (air) and reducing (1%-H2/Ar) atmospheres have been extracted from Arrhenius-plots. The oxygen nonstoichiometry in 1%-H2/Ar has been investigated by employing thermogravimetry. The decrease of the ionic conductivity under reducing conditions is accompanied by an increase of the corresponding high temperature activation energy of the bulk, which is interpreted in terms of defect association or clustering. 相似文献
180.
Pressurised operation of solid oxide fuel cells (SOFC) has been shown to significantly improve their performance (Singhal, 2000) [1], however little work has been done on the effects of pressure on SOFC cathodes. The effect of pressurised oxygen on the area specific polarisation resistance (ASRp) of (La0.8Sr0.2)0.95MnO3-δ/8YSZ SOFC cathodes was determined by electrochemical impedance spectroscopy (EIS). Pellets of 8YSZ were pressed and sintered at 1350 °C, and screen printed layers of LSM/8YSZ cathode and LSM current collector were applied and sintered at 1300 °C and 1200 °C respectively. EIS was carried out between 1 and 3 bar oxygen at 800-1000 °C. One process dominated the spectra, and was identified as process C, (Jorgensen and Morgensen, 2001) [2] by comparison of measured and reference frequency maxima, the dependence of polarisation resistance on PO2, the capacitance, and the activation energy. It is suggested that this represents the physical process of dissociative adsorption of oxygen at the triple phase boundaries of the electrode. A second process, with a magnitude almost independent of PO2, is observed, which may be process B [2], related to transport of oxygen ions in the YSZ. 相似文献