Synthesis and electrical properties of new solid state. Electrolyte materials Ce5.2RE0.8MoO15-delta

A series of solid state electrolytes, Ce-5.2 RE0.8 MoO15-delta (RE = Y, La, Sm, Gd, Dy, Ho, Er), were synthesized by sol-gel method. Their structures and electrical conductivities were characterized by X-ray Diffraction (XRD), Raman and X-ray Photoelectron Spectroscopy (XPS) and AC impedance spectroscopy, respectively. The results show that the concentrations of oxygen vacancy increased with increasing x and their conductivity were improved. And the cell parameters increase as the radius of RE3+ increases. Because the ionic radius of doped Dy3+ (0.0908 nm) is closed to that of Ce4+ (0.0920 nm), their oxide has minimal cell elastic straining between RE3+ and oxygen vacancy, and the system has the least association enthalpy, thus the oxide Ce-5.2 Dy-0.8 MoO15-delta exhibits a higher conductivity (7.02 x 10(-3) S/cm) and lower activation energy (1.056 eV) compared to the other doped compounds.

Synthesis, characterization and electrical properties of solid state electrolyte materials La2-xCaxMo1.7W0.3O9-delta (0 <= x <= 0.2)

The new compounds La2-xCaxMo1.7W0.3O9-delta (0 <= x <= 0.2) in which La3+ substituted with Ca2+ were synthesized by dry-chemistry techniques based on the oxygen Ionic conductor La2Mo1.7W0.3O9. The new series were characterized by X-ray Diffraction (XRD), Raman and X-ray Photoelectron Spectroscopy (XPS) and the electrical conductivity of samples were investigated by AC impedance spectroscopy. The lattice parameters were reduced due to the smaller atomic radius of the Ca2+ compared with that of the La3+. Furthermore, Additional oxygen vacancies were introduced into La2Mo1.7W0.3O9 lattice by substitution, and then the oxygen ionic conductivity was increased. At 550 degrees C, the conductivity increased 89.9%, that is, from 0.79 x 10(-4) S center dot cm(-1) (x=0) to 1.5 X 10(-4)S center dot cm(-1) (x=0.16, 0.2).

Grain boundary conductivity of high purity neodymium-doped ceria nanosystem with and without the doping of molybdenum oxide

Solid solutions of Ce1-xNdxO2-x/2 (0.05 <= x <= 0.2) and (Ce1-xNdx)(0.95)MO0.05O2-delta (0.05 <= x <= 0.2) have been synthesized by a modified sol-gel method. Both materials have very low content of SiO2 (similar to 27 ppm). Their structures and ionic conductivities were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and electrochemical impedance spectroscopy (M). The XRD patterns indicate that these materials are single phases with a cubic fluorite structure. The powders calcined at 300 degrees C with a crystal size of 5.7 nm have good sinterability, and the relative density could reach above 96% after being sintered at 1450 degrees C. With the addition Of MoO3, the sintering temperature could be decreased to 1250 degrees C. Impedance spectroscopy measurement in the temperature range of 250-800 degrees C indicates that a sharp increase of conductivity is observed when a small amount of Nd2O3 is added into ceria, of which Ce0.85Nd0.15O1.925 (15NDC) shows the highest conductivity. With the addition of a small amount Of MoO3, the grain boundary conductivity of 15NDC at 600 degrees C increases from 2.56 S m(-1) to 5.62 S m(-1).

Preparation and electrical-magnetic properties of polyaniline doped with ionic ferrocenesulfonic acid

Conducting polyamline with electrical conductivity of 2.34 x 10(-1) S cm(-1) was obtained using ferrocenesulfonic acid as dopant. After the ferrocenesulfonic acid was oxidized with FeCl3, though the electrical conductivity of the doped polyaniline decreased by 1-2 orders of magnitude, the magnetic susceptibility (chi) increased with the increase of the oxidation degree of ferrocenesulfonic acid. EPR spectra showed not only a signal with a g value of around 2, but also a so-called half-field signal with a g value of about 4 even at room temperature. Coexistence of ferromagnetic intrachain interactions and antiferromagnetic interchain interactions in the materials has been suggested.

Fabrication, characterization and conductivity of organic-inorganic hybrid Langmuir-Blodgett films based on polyquinoline and rare earth-substituted heteropolymolybdate

The organic/inorganic hybrid Langmuir-Blodgett (LB) films were obtained by the compact organization of poly(1,2-dihydro-2,2,4-trimethyl)quinoline (PQ), octadecylamine (ODA) and rare earth-substituted heteropolymolybdates. They were characterized by surface pressure-area (pi-A) isotherms, absorption spectra, fluorescence spectra, atomic force microscope (AFM) and scanning tunneling microscopy (STM). The atomic force microscope revealed a granular surface texture of nanosized rare earth-substituted heteropolymolybdate. The scanning tunneling microscopy indicated that the hybrid LB films containing rare earth-substituted heteropolymolybdates had the better electrical conductivity than LB film of PQ/ODA.

Memory devices based on lanthanide (SM3+, EU3+, Gd3+) complexes

Memory effects in single-layer organic light-emitting devices based on Sm3+, Gd3+, and Eu3+ rare earth complexes were realized. The device structure was indium-tin-oxide (ITO)/3,4-poly(ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT)/Poly(N-vinyl carbazole) (PVK): rare earth complex/LiF/Ca/Ag. It was found experimentally that all the devices exhibited two distinctive bistable conductivity states in current-voltage characteristics by applying negative starting voltage, and more than 10(6) write-read-erase-reread cycles were achieved without degradation. Our results indicate that the rare earth organic complexes are promising materials for high-density, low-cost memory application besides the potential application as organic light-emitting materials in display devices.

Synthesis, structural characterization and electrical property of new oxide ion conductors: La3MMo2O12 (M = In, Ga and Al)

New series of oxides, La3MMo2O12 (M = In, Ga and Al), have been prepared by the solid-state reaction. The composition and elemental distribution were analyzed by the energy-dispersive X-ray (EDX) analysis. As determined by the X-ray diffraction (XRD), these compounds have similar crystal structures that can be indexed on a monoclinic cell at room temperature. AC impedance spectra and the DC electrical conductivity measurements in various atmospheres indicate that they are oxide ion conductors with ionic conductivities between 10(-2) and 10(-3) S/cm at 800 degrees C. The conductivity decreases in the order of La3GaMo2O12 > La3AlMo2O12 > La3InMo2O12, implying that the effect of cell volume and polarization associated with In3+, Ga3+ and Al3+ play an important role in the anion transport of these materials. The reversible phase transition was observed in all these compounds as confirmed by the differential thermal analysis (DTA) and dilatometric measurements.

Synthesis, structural and electrical characterizations of Sr2Fe1-xMxNbO6 (M = Zn and Cu) with double perovskite structure

Sr2Fe1-xZnxNbO6-x/2 (0 <= x <= 0.5) and Sr2Fe1-xCuxNbO6-x/2 (0.01 <= x <= 0.05) with the double perovskite structure have been synthesized. The crystal structures at room temperature were determined from Rietveld refinements of X-ray powder diffraction data. The plots of the imaginary parts of the impedance spectrum, Z '', and the electric modulus, M '', versus log (frequency), possess maxima for both curves separated by less than a half decade in frequency with associated capacities of 2 nF. The enhancement of the overall conductivity Of Sr2Fe1-xMxNbO6-x/2 (M = Cu and Zn) is observed, as increases from 2.48 (3) x 10(-4) S/cm for Sr2FeNbO6 to 3.82 (5) x 10(-3) S/cm for Sr2Fe0.8Zn0.2NbO5.9 at 673 K. Sr2Fe0.8Zn0.2NbO5.9 is chemically stable under the oxygen partial pressure from 1 atm to 10(-22) atm at 873 K. The p and n-type electronic conductions are dominant under oxidizing and reducing conditions, respectively, suggesting a small-polaron hopping mechanism of electronic conduction.

Synthesis, characterization and electrical properties of the new solid electrolyte materials Ce6-xErxMoO15-delta (0.0 < x < 1.5)

A new series of oxides, Ce6-xErxMoO15-delta (0.0 less than or equal to x less than or equal to 1.5), was synthesized using wet-chemistry techniques. The precursors and resultant oxide powders were characterized by differential thermal analysis/thermogravimetry, x-ray diffraction, and IR, Raman and x-ray photoelectron spectroscopy. The formation temperature of the powders was found to be as low as 350degreesC. Ce6-xErxMoO15-delta crystallized to a fluorite-related cubic structure. The electrical conductivity of the samples was investigated by using ac impedance spectroscopy. This showed that the presence of Er was related to the oxygen-ion conductivity, and that the highest oxygen-ion conductivity was found in Ce6-xErxMoO15-delta (x = 0.4), ranging from 5.9 x 10(-5) S cm(-1) at 300degreesC to 1.26 x 10(-2) S cm(-1) at 700degreesC, respectively. This kind of material shows a potential application in intermediate-temperature solid oxide fuel cells.

Processible nanomaterials with high conductivity and magnetizability. Preparation and properties of maghemite/polyaniline nanocomposite films

A versatile process employing anionic surfactants has been developed for the preparation of processible nanocomposite films with electrical conductivity and magnetic susceptibility. Maghemite (g-Fe2O3) nanoclusters (similar to 10 nm in size) are coated with 4-dodecyl- benzenesulfonic acid, and polyaniline (PAn) chains are doped with 10-camphorsulfonic acid. The coated nanoclusters and doped polymers are soluble in common solvents, and casting the solutions readily gives free-standing nanocomposite films with nanocluster contents as high as similar to 50 wt %. The g-Fe2O3/PAn nanocomposites show high conductivity (82-337 S cm(-1)) and magnetizability (up to similar to 35 emu/g g-Fe2O3).

Sol-gel synthesis and electrical properties of ceria-based solid electrolytes

A series of solid electrolytes (Ce0.8RE0.2)(1-x)MxO2-delta(RE: Rare earth, M: Alkali earth) were prepared by sol-gel methods. XRD indicated that a pure fluorite phase was formed at 800 degrees C. The synthesis temperature by the sol-gel methods was about 700 degrees C lower than by the traditional ceramic method. The electrical conductivity and impedance spectra were measured. XPS showed that the oxygen vacancy increased obviously by doping MO, thus, resulting in the increase of the oxygen ionic transport number and conductivity. The performance of ceria-based solid electrolyte was improved. The effects of RE2O3 and MO on the electrical properties were discussed. The conductivity and the oxygen ionic transport number of (Ce0.8Sm0.2)(1-0.05)Ca0.05O2-delta is 0.126 S.cm(-1) and 0.99 at 800 degrees C, respectively.

Synthesis, electrical properties and crystal structure of a new radical-ion salt based on pi-extended bis(TTF) and a Keggin heteropolymolybdate

By electrocrystallization of 2,6-[4,5-bis(n-butylsulfanyl)-1,3-dithiol-2-ylidene]-4,8-bis(6-iodo-n-hexyloxy)-1,3,5,7-tetrathia-s-indacene (BHBDTI) and [NBu4](4)[SiMo12O40] in the mixed solvent CHCl2CH2Cl and CH3CN, the new radical-ion salt [C42H60Cl2O2S12](2)[SiMo12O40] was prepared. It was characterized by means of IR and ESR spectroscopy and X-ray diffraction. In the crystal structure, organic radical dications and silicomolybdate anions are alternatively arranged along the a axis to form a 1-D conducting layer. The organic layer consists of two isolated groups of BHBDTI divided by the (011) plane without short interatomic contacts. However, in each group, BHBDTI molecules associate with each other in a head to tail manner running along the [011] direction and face-to-face overlapping with a relative shift by approximately one TTF subunit along the long axis of the molecule and a slight shift along the short axis of the molecule with significantly short S ... S contacts. The room-temperature d.c. conductivity determined by the two-probe method is 10(-4) S cm(-1), suggesting that the compound is a semiconductor.

Observational evidence of the Yellow Sea warm current

The Yellow Sea Warm Current (YSWC) is one of the principal currents in the Yellow Sea in winter. Former examinations on current activity in the Yellow Sea have not observed a stable YSWC because of the positioning of current meters. To further understand the YSWC, a research cruise in the southern Yellow Sea was carried out in the winter of 2006/2007. Five moorings with bottom-mounted acoustic Doppler current profilers (ADCP) were deployed on the western side of the central trough of the Yellow Sea. The existence and distributional features of the YSWC were studied by analyzing three ADCP moorings in the path of the YSWC in conjunction with conductivity-temperature-depth (CTD) data over the observed area in the southern Yellow Sea. The results show the following. (1) The upper layer of the YSWC is strongly influenced by winter cold surge; its direction and speed often vary along a south-north axis when strong cold surges arrive from the north. (2) The YSWC near the bottom layer is a stable northwest flowing current with a speed of 4 to 10 cm/s. By combining the analyses of the CTD data, we speculate that the core of the YSWC may lie near the bottom. (3) On a monthly average timescale, the YSWC is stably oriented with northward flow from the sea surface to the sea floor.

Effective response of a non-linear composite in external AC electric field

A general effective response is proposed for nonlinear composite media, which obey a current field relation of the form J = sigmaE + chi\E\(2) E when an external alternating current (AC) electrical field is applied. For a sinusoidal applied field with finite frequency omega, the effective constitutive relation between the current density and electric field can be defined as, = sigma(e) + chi(e) <\E(x, omega, t)\(2) E(x, omega, t)> + (. . .), where sigma(e) and chi(e) are the general effective linear and nonlinear conductive responses, respectively. The angled brackets <(. . .)> denotes the ensemble average. As two examples, we have investigated the cylindrical and spherical inclusions embedded in a host and also derived the formulae of the general effective linear and nonlinear conductive responses in dilute limit. For higher volume fraction of inclusions, we have proposed a nonlinear effective medium approximation (EMA) method to estimate the general effective response of nonlinear composites in external AC field. Furthermore, the effective nonlinear responses at harmonics are predicted by using the general effective response. (C) 2002 Elsevier Science B.V. All rights reserved.

A study of electrical chloride extraction of iron artifacts

The chloride extraction rule of iron artifacts was studied by electrical methods. The effect of the current and potential value on the desalination result of simulated iron artifacts was studied through the galvanostatic and potentiostatic experiments the ingredients of the rust before and after treatments were also analyzed by the X-ray diffraction (XRD). It has been found that the optimal current density was between -0.50 and -0.75 mA/cm(2) and the optimal potential was between -1.175 and -1.200 V. The phase of the samples rusts transformed after treatment, as well as the anti-corrosion performance improved.