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Tejero EM Amatucci WE Ganguli G Cothran CD Crabtree C Thomas E 《Physical review letters》2011,106(18):185001
Laboratory observations of electromagnetic ion-cyclotron waves generated by a localized transverse dc electric field are reported. Experiments indicate that these waves result from a strong E×B flow inhomogeneity in a mildly collisional plasma with subcritical magnetic field-aligned current. The wave amplitude scales with the magnitude of the applied radial dc electric field. The electromagnetic signatures become stronger with increasing plasma β, and the radial extent of the power is larger than that of the electrostatic counterpart. Near-Earth space weather implications of the results are discussed. 相似文献
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Andrei Jitianu John Doyle Glenn Amatucci Lisa C. Klein 《Journal of Sol-Gel Science and Technology》2010,53(2):272-279
Hybrid melting gels were prepared by a sol–gel process, starting with a mono-substituted siloxane and a di-substituted siloxane.
Methyl-modified melting gels were prepared using (a) methyltriethoxysilane (MTES) with dimethyldiethoxysilane (DMDES) and
(b) methyltrimethoxysilane (MTMS) together with dimethyldimethoxysilane (DMDMS). The gels with MTES–DMDES were prepared with
concentrations between 50–50 and 75–25 mol%. The gels with MTMS–DMDMS were prepared with concentrations between 50–50 and
70–30 mol%. For both systems, the consolidation temperature, after which the melting gel no longer softens, increased with
an increase in the amount of the mono-substituted siloxane, increasing from 135 to 160 °C for MTES–DMDES and increasing from
145 to 170 °C for MTMS–DMDMS. Coatings formed on mica substrates were about 1 mm thick, and showed no visible cracks. The
surfaces of the coatings were profiled using micro-Raman spectroscopy, which revealed that methyl groups were concentrated
at the surfaces of the films. All contact angles measured with water were greater than 90°. 相似文献
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In this study,the three dimensional nanoscale organization in the photoactive layers of poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM) is revealed by transmission electron tomography.After annealing treatment,either at elevated temperature or during slow solvent evaporation,nanoscale interpenetrating networks are formed with high crystalline order and favorable concentration gradients of both components through the thickness of the photoactive layer.Such a tailored morphology acco... 相似文献
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Li3Sc2(PO4)3 is a promising candidate for use as an electrolyte in solid state lithium rechargeable microbatteries due to its stability in air, ease of preparation, and resistance to dielectric breakdown. The room temperature ionic conductivity was optimized resulting in an increase of over two orders of magnitude to 3×10−6S/cm. The formation of Li3(Sc2−xMx)(PO4)3, where M=Al3+ or Y3+, resulted in the decrease of porosity, greater sinterability, and considerable enhancement of the ionic conductivity. Yttrium substitutions enhanced the conductivity slightly while aluminum increased the room temperature ionic conductivity to 1.5×10−5S/cm for x=0.4. Preliminary electron beam evaporation of Li3Sc2(PO4)3 yielded amorphous thin films with ion ic conductivity as high as 5×10−5S/cm and a composition of Li4.8Sc1.4(PO4)3. 相似文献
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Electron energy loss spectroscopy (EELS) is a powerful technique for studying Li-ion battery materials because the valence state of the transition metal in the electrode and charge transfer during lithiation and delithiation processes can be analyzed by measuring the relative intensity of the transition metal L3 and L2 lines. In addition, the Li distribution in the electrode material can be mapped with nanometer scale resolution. Results obtained for FeO0.7F1.3/C nanocomposite positive electrodes are presented. The Fe average valence state as a function of lithiation (discharge) has been measured by EELS and results are compared with average Fe valence obtained from electrochemical data. For the FeO0.7F1.3/C electrode discharged to 1.5 V, phase decomposition is observed and valence mapping with sub-nanometer resolution was obtained by STEM/EELS analysis. For the lowest discharge voltage of 0.8 V, a surface electrolyte inter-phase (SEI) layer is observed and STEM/EELS results are compared with the Li-K edges obtained for various Li standard compounds (LiF, Li2CO3 and Li2O). 相似文献
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I. Plitz A. DuPasquier F. Badway J. Gural N. Pereira A. Gmitter G.G. Amatucci 《Applied Physics A: Materials Science & Processing》2006,82(4):615-626
In order to address power demands of mobile electronics, engineers have been relegated to the incorporation of energy storage
technologies with wide disparities in energy and power performance. This paper will review and present alternative non aqueous
chemistries and enabling electroactive materials that have the potential to fill a critical void in the power/energy spectrum
and enable the design of new and/or improved devices. Incorporating one of the first uses of inorganic intercalation nanomaterials
in energy storage, the asymmetric hybrid technology was developed in order to significantly increase the energy density of
the supercapacitor, while maintaining the power and most importantly the robustness. The technology delivers 10–15 Wh/kg at
1000–2000 W/kg for over 450000 full discharge cycles. For certain applications, cycle life is not a key specification but
rather high power and energy. New composites were developed to address these needs and were optimized to result in systems
with 30–45 Wh/kg at upwards of 3000 to 5000 W/kg,while maintaining excellent low temperature performance and fast recharge
capability. The performance of these and other alternative systems are presented relative to the active materials, composition
of electrodes and electrolytes, failure modes, characterization, and cell design.
PACS 81.05.2; 81.70; 84.60; 84.60.D 相似文献
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Frederic Cosandey Jafar F Al-Sharab Fadwa Badway Glenn G Amatucci Pierre Stadelmann 《Microscopy and microanalysis》2007,13(2):87-95
A new type of positive electrode for Li-ion batteries has been developed recently based on FeF3/C and FeF2/C nanocomposites. The microstructural and redox evolution during discharge and recharge processes was followed by electron energy loss spectroscopy (EELS) to determine the valence state of Fe by measuring the Fe L3 line energy shift and from Fe L3/L2 line intensity ratios. In addition, transition metal fluorides were found to be electron beam sensitive, and the effect of beam exposure on EELS spectra was also investigated. The EELS results indicate that for both FeF3/C and FeF2/C nanocomposite systems, a complete reduction of iron to FeO is observed upon discharge to 1.5 V with the formation of a finer FeO/LiF subnanocomposite ( approximately 7 nm). Upon complete recharging to 4.5 V, EELS data reveal a reoxidation process to a Fe2+ state with the formation of a carbon metal fluoride nanocomposite related to the FeF2 structure. 相似文献
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Koepke M.E. Amatucci W.E. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(6):631-635
The influence of transverse, localized, DC electric fields (TLEs) on the current-driven electrostatic ion-cyclotron (CDEIC) instability is being investigated in a Q machine. A small (diameter ~10 ion gyroradii) segmented disk electrode is being used to excite the mode in a narrow electron-current channel along which exists a radial electric field between regions that magnetically map to the different circular segments (separated by a radial gap of ~3 ion gyroradii). Experiments aimed at demonstrating a TLE dependence in the threshold current for mode excitation are described. A comparison of observed and predicted mode frequencies over a range of magnetic field strengths is presented for the benchmark case of no applied transverse electric field. When the electric field is present, ion-cyclotron fluctuations are observed for cases in which the current is below the CDEIC instability threshold 相似文献