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Electronic Conductivity (electronic + conductivity)
Selected Abstracts3,4-Ethylenedioxythiophene,Pyridine-Based Polymers: Redox or n-Type Electronic Conductivity?ADVANCED MATERIALS, Issue 24 2002C.J. DuBois A family of polymers based on alternating bi-EDOT and pyridine units is reported. Poly(BEDOT-PyrPyr-Ph2), with a bandgap of 1.2 eV, has four electrochemically accessible colors (dark gray, burgundy, lime green, and light gray) each corresponding to a distinct redox state. In-situ conductance measurements illustrate high n-type doping conductances only thirty times less than those of the p-type doping conductances. [source] ChemInform Abstract: First Observation of Electronic Conductivity in Mixed-Valence Tellurium Oxides.CHEMINFORM, Issue 11 2010Theeranun Siritanon Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Conductive Nanoscopic Fibrous Assemblies Containing Helical Tetrathiafulvalene StacksCHEMISTRY - AN ASIAN JOURNAL, Issue 9 2009Yoko Tatewaki Dr. Abstract Tetrathiafulvalenes (TTF) S -TTF and R -TTF having four chiral amide end groups self-organize into helical nanofibers in the presence of 2,3,5,6-tetrafluoro-7,7,,8,8,-tetracyano- p -quinodimethane (F4TCNQ). The intermolecular hydrogen bonding among chiral amide end groups and the formation of charge-transfer complexes results in a long one-dimensional supramolecular stacking, and the chirality of the end groups affects the molecular orientation of TTF cores within the stacks. Electronic conductivity of a single helical nanoscopic fiber made of S -TTF and F4TCNQ is determined to be (7.0±3.0)×10,4,S,cm,1 by point-contact current-imaging (PCI) AFM measurement. Nonwoven fabric composed of helical nanofibers shows a semiconducting temperature dependence with an activation energy of 0.18,eV. [source] Ion-Conducting Probes for Low Temperature PlasmasCONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-7 2008S. A. Meiss Abstract Probes interacting with a low temperature plasma are typically built of electron conducting materials, mostly metals. We apply yttria-stabilized zirconia (YSZ) which is oxygen ion conducting at elevated temperatures and which is a typical solid electrolyte with high ionic and negligible electronic conductivity. The processes at the plasma|YSZ interface are discussed and first results of measurements with ion-conducting single- and double-probes in oxygen containing radio frequency plasmas are presented. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nitrogen-doped zirconia single crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2006T.-C. Rödel Abstract The aim of this work is the preparation of nitrogen-doped single crystals of cation-stabilized zirconia. Thin plates of these crystals were nitrided in a graphite heated resistance furnace with nitrogen as reaction gas. Several dwell times and reaction temperatures were tested and their effect on the amount of incorporated nitrogen is investigated. During nitridation at high temperatures a rock salt-type ,ZrN' layer grows on the surface, leading to the destruction of the crystal. In contrast to the fluorite-type bulk material, which can be described as a fast anion conductor, the surface layer shows electronic conductivity. For possible applications of the bulk material (solid electrolyte) the formation of the surface layer must be avoided. Therefore, the interface between surface epilayer and bulk material was investigated in detail by electron microscopy methods. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Functionally Graded Layers Prepared by Atmospheric Plasma Spraying for Solid Oxide Fuel Cells,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009W. S. Xia Two functionally graded layers between the electrolyte and adjacent electrodes were prepared by atmospheric plasma spraying (APS) for solid oxide fuel cells (SOFCs). Both the porosity and material compositions gradually vary in the two graded layers. The SOFC with the graded layers has higher electronic conductivity and far lower interface resistance than that without graded layers. [source] Tests for the Use of La2Mo2O9 -based Oxides as Multipurpose SOFC Core MaterialsFUEL CELLS, Issue 3 2010J. Jacquens Abstract The mixed ionic,electronic conductivity under dilute hydrogen, the stability and the catalytic activity under propane:air type mixtures of a series of LAMOX oxide-ion conductors have been studied. The effect of exposure to dilute hydrogen on the conductivity of the ,-La2(Mo2,,,yWy)O9 series at 600,°C depends on tungsten content: almost negligible for the highest (y,=,1.4), it is important for La2Mo2O9 (y,=,0). In propane:air, all tested LAMOX electrolytes are stable at 600,700,°C, but get reduced when water vapour is present. La2Mo2O9 is the best oxidation catalyst of the series, with an activity comparable to that of nickel. The catalytic activity of other tested LAMOX compounds is much lower, (La1.9Y0.1)Mo2O9 showing a deactivation phenomenon. These results suggest that depending on composition, La2(Mo2,,,yWy)O9 compounds could be either electrolytes in single-chamber SOFC and dual-chamber micro-SOFC (y,=,1.4) or anode materials in dual-chamber SOFC (low y) or oxidation catalysts in SOFCs operating with propane (y,=,0). [source] Temperature and Impurity Concentration Effects on Degradation of Nickel/Yttria-stabilised Zirconia Anode in PH3 -Containing Coal SyngasFUEL CELLS, Issue 1 2010M. Zhi Abstract Degradation of the Ni/yttria-stabilised zirconia (YSZ) anode of the solid oxide fuel cell has been evaluated in the coal syngas containing different PH3 concentrations in the temperature range from 750 to 900,°C. Thermodynamic equilibrium calculations show that PH3 in the coal syngas gas is converted mostly to P2O3 at 750,900,°C. The phosphorous impurity reacts with the Ni-YSZ anode to form phosphates. The P-impurity poisoning leads to the deactivation of the Ni catalyst and to the reduction in the electronic conductivity of the anode. The impurity poisoning effect on the anode is exacerbated by increase in the temperature and/or the PH3 concentration. [source] Ionic-Liquid-Doped Polyaniline Inverse Opals: Preparation, Characterization, and Application for the Electrochemical Impedance Immunoassay of Hepatitis B Surface AntigenADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Xing-Hua Li Abstract A 3D ordered macroporous (3DOM) ionic-liquid-doped polyaniline (IL-PANI) inverse opaline film is fabricated with an electropolymerization method and gold nanoparticles (AuNPs) are assembled on the film by electrostatic adsorption, which offers a promising basis for biomolecular immobilization due to its satisfactory chemical stability, good electronic conductivity, and excellent biocompatibility. The AuNP/IL-PANI inverse opaline film could be used to fabricate an electrochemical impedance spectroscopy (EIS) immunosensor for the determination of Hepatitis B surface antigen (HBsAg). The concentration of HBsAg is measured using the EIS technique by monitoring the corresponding specific binding between HBsAg and HBsAb (surface antibody). The increased electron transfer resistance (Ret) values are proportional to the logarithmic value of the concentration of HBsAg. This novel immunoassay displays a linear response range between 0.032,pg mL,1 and 31.6,pg mL,1 with a detection limit of 0.001,pg mL,1. The detection of HBsAg levels in several sera showed satisfactory agreement with those using a commercial turbidimetric method. [source] Research on Advanced Materials for Li-ion BatteriesADVANCED MATERIALS, Issue 45 2009Hong Li Abstract In order to address power and energy demands of mobile electronics and electric cars, Li-ion technology is urgently being optimized by using alternative materials. This article presents a review of our recent progress dedicated to the anode and cathode materials that have the potential to fulfil the crucial factors of cost, safety, lifetime, durability, power density, and energy density. Nanostructured inorganic compounds have been extensively investigated. Size effects revealed in the storage of lithium through micropores (hard carbon spheres), alloys (Si, SnSb), and conversion reactions (Cr2O3, MnO) are studied. The formation of nano/micro core,shell, dispersed composite, and surface pinning structures can improve their cycling performance. Surface coating on LiCoO2 and LiMn2O4 was found to be an effective way to enhance their thermal and chemical stability and the mechanisms are discussed. Theoretical simulations and experiments on LiFePO4 reveal that alkali metal ions and nitrogen doping into the LiFePO4 lattice are possible approaches to increase its electronic conductivity and does not block transport of lithium ion along the 1D channel. [source] Synthesis, Structure, and Electrochemical Characterization of Nanocrystalline Tantalum and Tungsten NitridesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2007Daiwon Choi Nanocrystalline tantalum and tungsten nitrides were synthesized by a two-step ammonolysis reaction of transition metal chlorides. The first step involves ammonolysis of tantalum and tungsten chlorides at room temperature using anhydrous chloroform as the solvent. A second step consists of heat treatment of these as-prepared powders under anhydrous NH3 atmosphere leading to the formation of tantalum and tungsten nitride nanocrystallites at relatively low temperature (600°,675°C). The ammonolysis, nitridation, structure, morphology, surface area, density, and electronic conductivity of the nitrides obtained were studied and characterized. The electrochemical responses of these nitrides were also measured by cyclic voltammetry using 1M KOH electrolyte. [source] Electrical Conductivity and Lattice Defects in Nanocrystalline Cerium Oxide Thin FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2001Toshio Suzuki The results of the electrical conductivity and Raman scattering measurements of CeO2 thin films obtained by a polymeric precursor spin-coating technique are presented. The electrical conductivity has been studied as a function of temperature and oxygen activity and correlated with the grain size. When compared with microcrystalline samples, nanocrystalline materials show enhanced electronic conductivity. The transition from extrinsic to intrinsic type of conductivity has been observed as the grain size decreases to <100 nm, which appears to be related to a decrease in the enthalpy of oxygen vacancy formation in CeO2. Raman spectroscopy has been used to analyze the crystalline quality as a function of grain size. A direct comparison has been made between the defect concentration calculated from coherence length and nonstoichiometry determined from electrical measurements. [source] Studies on semiconductor dispersed polymer electrolyte composite (PEO:NH4ClO4 + Bi2S3)PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2008Manoj Kumar Abstract Polymer composites consisting of different amounts (0,10 wt%) of dispersed semiconducting Bi2S3 in the polymer electrolyte polyethylene oxide complexed with NH4ClO4 (PEO:NH4ClO4 + Bi2S3) have been prepared and characterized. The dispersal of Bi2S3 was achieved by its "in-situ" formation in the polymeric solution by sulfuration of Bismuth nitrate by bubbling H2S. The dispersed Bi2S3 particles were found to be nano-sized (,20 nm) resulting in a higher band gap (,1.8 eV) as compared to that of bulk Bi2S3 (,1.4 eV). Detailed I ,V and polarization studies show that the dispersed Bi2S3 is n-type and a small (,8%) electronic conductivity is introduced into the purely ionic (PEO:NH4ClO4) film making it a mixed ion + electron conducting polymer composite. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Direct utilization of ethanol on ceria-based anodes for solid oxide fuel cellsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009Massimiliano Cimenti Abstract The direct utilization of ethanol was investigated in CuCeO2, CuZr0.35Ce0.65O2 (ZDC) and Cu/RuZr0.35Ce0.65O2 anodes for solid oxide fuel cells (SOFC). The anodes were prepared by impregnation with nitrate precursors on a porous layer of yttria-stabilized zirconia (YSZ) obtained by tape casting, while (La0.8Sr0.2MnO3,,) LSM cathodes were screen-printed. The cells were tested in both hydrogen and ethanol. The outlet gas composition was monitored with a gas chromatograph, which showed that almost all the ethanol was decomposed, mainly to H2, CH4, CO, H2O and C2H4. The maximum power outputs obtained in ethanol were 0.075 and 0.400 W/cm2 on CuCeO2|YSZ|LSM and CuZDC|YSZ|LSM, respectively. All cells were more active in alcohol than in hydrogen with the peak performance occurring after approximately 4 h. That is, the power density initially increased, peaked and then decreased. This behavior was likely a consequence of carbon deposition that initially results in an improvement of the electronic conductivity in the anode but later results in the blocking of the active sites. Zirconia doping (in the ZDC anodes) resulted in better stability and, in addition, the initial activity of the ZDC anodes could be recovered after approximately 1 h of exposure to humidified hydrogen, whereas the initial activity of the ceria anodes could not be recovered. The addition of ruthenium (<0.5 wt%) further improved the stability by delaying the onset of carbon formation. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||||||||