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31.
Buschmann H Dölle J Berendts S Kuhn A Bottke P Wilkening M Heitjans P Senyshyn A Ehrenberg H Lotnyk A Duppel V Kienle L Janek J 《Physical chemistry chemical physics : PCCP》2011,13(43):19378-19392
The solid lithium-ion electrolyte "Li(7)La(3)Zr(2)O(12)" (LLZO) with a garnet-type structure has been prepared in the cubic and tetragonal modification following conventional ceramic syntheses routes. Without aluminium doping tetragonal LLZO was obtained, which shows a two orders of magnitude lower room temperature conductivity than the cubic modification. Small concentrations of Al in the order of 1 wt% were sufficient to stabilize the cubic phase, which is known as a fast lithium-ion conductor. The structure and ion dynamics of Al-doped cubic LLZO were studied by impedance spectroscopy, dc conductivity measurements, (6)Li and (7)Li NMR, XRD, neutron powder diffraction, and TEM precession electron diffraction. From the results we conclude that aluminium is incorporated in the garnet lattice on the tetrahedral 24d Li site, thus stabilizing the cubic LLZO modification. Simulations based on diffraction data show that even at the low temperature of 4 K the Li ions are blurred over various crystallographic sites. This strong Li ion disorder in cubic Al-stabilized LLZO contributes to the high conductivity observed. The Li jump rates and the activation energy probed by NMR are in very good agreement with the transport parameters obtained from electrical conductivity measurements. The activation energy E(a) characterizing long-range ion transport in the Al-stabilized cubic LLZO amounts to 0.34 eV. Total electric conductivities determined by ac impedance and a four point dc technique also agree very well and range from 1 × 10(-4) Scm(-1) to 4 × 10(-4) Scm(-1) depending on the Al content of the samples. The room temperature conductivity of Al-free tetragonal LLZO is about two orders of magnitude lower (2 × 10(-6) Scm(-1), E(a) = 0.49 eV activation energy). The electronic partial conductivity of cubic LLZO was measured using the Hebb-Wagner polarization technique. The electronic transference number t(e-) is of the order of 10(-7). Thus, cubic LLZO is an almost exclusive lithium ion conductor at ambient temperature. 相似文献
32.
Methods for determining the heat content E
*/A of hot nuclei formed in energetic nuclear reactions are discussed. The primary factors involved in converting raw data into
thermal physics distributions include: 1) design of the detector array, 2) constraints imposed by the physics of the reaction
mechanism, and 3) assumptions involved in converting the filtered data into E
*/A. The two primary sources of uncertainty in the calorimetry are the elimination of nonequilibrium emissions from the event
components and accounting for the contribution of neutron emission to the excitation energy sum. 相似文献
33.
Wittko Francke 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》1993,105(8):1278-1279
34.
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The correlation between the plasma resistance and the laser output parameters has been investigated in pulsed CO2 — N2 discharges. The strong increase of the discharge resistance during gas degradation can be explained on the basis of strong attaching gas components. In degraded mixtures a supression of discharge instabilities together with the restoration of the laser pulse energy is possible by increasing the reduced electric field E/N temporarily. 相似文献
37.
Tullio Viola 《Annali di Matematica Pura ed Applicata》1960,49(1):367-373
Sunto Si disente criticamente il detto postulato, con particolare riguardo al problema della sua compatibilità entro il sistema
ipotetico — deduttivo dell'Hilbert.
A Giovanni Sansone nel suo 70mo compleanno. 相似文献
38.
Below TN, the site symmetry at the Mn2+ ion is centrosymmetric (Rb2MnCl4) and non-centrosymmetric (Rb3Mn2Cl7) respectively. As a result, one expects the appearance of magnetic dipole or electric dipole exciton origins in the optical spectra. These were clearly seen via polarized absorption and magnetic circular dichroism measurements through the 4T2(D) band. The zone edge magnon frequencies are found to be 80 cm?1 (Rb2MnCl4) and 90 cm?1 (Rb3MnCl2in7). The two compounds are also easily distinguished through their room temperature axial absorption (4T2 (G) band) and Raman spectra. Low temperature data indicate that the tetragonal field plays an important role. 相似文献
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Tullio Viola 《Annali di Matematica Pura ed Applicata》1955,39(1):381-391
Sunto Si studia una definizione del tutto generale di funzione quasi continua; si enuncia e dimostra poi un teorema, concettualmente
nuovo, per le successioni di funzioni che sono quasi continue nel senso generale studiato.
A Mauro Picone nel suo 70mo compleanno.
Lavoro eseguito presso l'Istituto Nazionale per le Applicazioni del Calcolo. 相似文献