Bulk Conductivity (bulk + conductivity)

Distribution by Scientific Domains

Selected Abstracts

Low-Temperature Superionic Conductivity in Strained Yttria-Stabilized Zirconia

Michael Sillassen
Abstract Very high lateral ionic conductivities in epitaxial cubic yttria-stabilized zirconia (YSZ) synthesized on single-crystal SrTiO3 and MgO substrates by reactive direct current magnetron sputtering are reported. Superionic conductivities (i.e., ionic conductivities of the order ,1 ,,1cm,1) are observed at 500,C for 58-nm-thick films on MgO. The results indicate a superposition of two parallel contributions , one due to bulk conductivity and one attributable to conduction along the film,substrate interface. Interfacial effects dominate the conductivity at low temperatures (<350,C), showing more than three orders of magnitude enhancement compared to bulk YSZ. At higher temperatures, a more bulk-like conductivity is observed. The films have a negligible grain-boundary network, thus ruling out grain boundaries as a pathway for ionic conduction. The observed enhancement in lateral ionic conductivity is caused by a combination of misfit dislocation density and elastic strain in the interface. These very high ionic conductivities in the temperature range 150,500,C are of great fundamental importance but may also be technologically relevant for low-temperature applications. [source]

Controlling Electrical Properties of Conjugated Polymers via a Solution-Based p-Type Doping,

Keng-Hoong Yim
Tetrafluoro-tetracyano-quinodimethane (F4TCNQ) is used to p-dope conjugated polymers with a wide range of the HOMO levels via co-blending in a common organic solvent. Doping results in several orders of magnitude increase in the bulk conductivity and hole-current with reduced turn-on voltage. The effectiveness of doping increases as the HOMO level of the polymer becomes smaller. [source]

Synthesis of Co3O4/Poly(N -vinylcarbazole) Core/Shell Composite With Enhanced Optical Property

Arjun Maity
Abstract Co3O4/poly(N -vinylcarbazole) (PNVC) composite with enhanced optical property was synthesized via a simple in situ bulk polymerization of NVC monomers in the presence of Co3O4 nanoparticles at an elevated temperature. High-resolution electron microscopic observations showed that the Co3O4 nanoparticles were coated with uniform nanolayer shells of PNVC. Fourier-transform infrared (FT-IR) spectroscopy revealed the presence of strong interactions between the PNVC polymer chains with the Co3O4 surface in the Co3O4/PNVC composite. Raman spectroscopic results supported conclusions based on electron microscopy and FT-IR spectra. The uniform nanolayer coating of PNVC decreases the inherent bulk conductivity of Co3O4, however, significantly increases the fluorescence property of Co3O4 nanoparticles. [source]

Electrical transport properties of aliovalent cation-doped CeO2

Mark C. Pearce
Abstract We report the comparative electrical properties of monovalent (Na+), divalent (Ca2+, Sr2+), trivalent (In3+, La3+) and coupled substitution of divalent and trivalent (Ca2+ + Sm3+) cation-doped CeO2. The investigated samples were prepared by solid-state reaction (ceramic) using the corresponding metal oxides and salts in the temperature range 1000,1600 C in air. Powder X-ray diffraction (PXRD), laser particle size analysis (LPSA), scanning electron microscopy (SEM), and ac impedance spectroscopy measurements were employed for structural, morphology, and electrical characterization. PXRD studies reveal the formation of single-phase cubic fluorite-type structures for all investigated samples except those doped with In3+. The variation of lattice parameters is consistent with ionic radii (IR) of the dopant metal ions, with the exception of Na+ -doped CeO2. Our attempt to substitute In3+ for Ce4+ in CeO2 using both ceramic and wet chemical methods was unsuccessful. Furthermore, diffraction peaks attributed to CeO2 and In2O3 were observed up to sintering conditions of 1600 C. Among the single-phase compounds investigated, Ce0.85Ca0.05Sm0.1O1.9 exhibits the highest bulk conductivity of 1.3 10,3 S/cm at 500 C with activation energy of 0.64 eV in air. The electrical conductivity data obtained for Ce0.85Ca0.05Sm0.1O1.9 in air and Ar were found to be very similar over the investigated temperature range, indicating the absence of p-electronic conduction in the high oxygen partial pressure (pO2) range which is consistent with literature reported on Sm-doped CeO2. Copyright 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

A New Oxide Ion Conductor: La3GaMo2O12

Tian Xia
Abstract A new oxide ion conductor, La3GaMo2O12, with a bulk conductivity of 2.710,2 Scm,1 at 800 C in air atmosphere was prepared by the traditional solid-state reaction. The room temperature X-ray diffraction data could be indexed on a monoclinic cell with lattice parameters of a=0.5602(2) nm, b=0.3224(1) nm, c=1.5741(1) nm, ,=102.555(0), V=0.2775(2) nm3 and space group Pc(7). Ac impedance measurements in various atmospheres further support that it is an oxide ion conductor. This material was stable in various atmospheres with oxygen partial pressure p(O2) ranging from 1.0105 to 1.010,7 Pa at 800 C. A reversible polymorphic phase transition occurred at elevated temperatures as confirmed by the differential thermal analysis and dilatometric measurement. [source]