New typical ionic cluster K+(KNO3)(n) and NO3-(KNO3)(m)

New typical ionic clusters with complex anions could be formed directly from the KNO3 aqueous solution by means of the electrospray ionization mass spectrometry(ESIMS). The difference between the neighboring peaks(m/z), which corresponded to the molecule weight of KNO3 being 101 in the full mass spectrometry of the positive-ion and the negative-ion. The general formula of the ionic clusters belonged to K+(KNO3)(n) and NO3- (KNO3)(m).

Thermal influence on excimer-laser-induced electrical conductivity on polyimide film surfaces

The thermal influence on the electrical conductivity of polyimide film surfaces induced by KrF-laser irradiation was investigated, The formation of conducting phases was demonstrated to be highly temperature sensitive, as evidenced by strong dependence of the electrical conductivity on repetition rate and ambient temperature. XPS and Raman studies showed that the efficiency of the formation of conducting phases could be enhanced by the increase of temperature on irradiated polyimide film surfaces. After the disruption of polymeric chain, the carbon-enriched clusters remained on the irradiated polyimide film surfaces organized into polycrystalline graphite-like clusters responsible for electrical conductivity. The resulting dangling bonds from the decomposition process of polyimide acted as centers for the rearrangement of carbon-enriched clusters. It is suggested that the motion of radicals was promoted with increasing the temperature. Therefore the formation of polycrystalline graphite-like clusters benefited from high remaining temperature on the irradiated polyimide film surfaces. These results revealed that thermal influence played a dominant role on the formation of conducting phases.

Processible nanostructured materials with electrical conductivity and magnetic susceptibility: Preparation and properties of maghemite polyaniline nanocomposite films

We here present a versatile process for the preparation of maghemite/polyaniline (gamma-Fe2O3/ PAn) nanocomposite films with macroscopic processibility, electrical conductivity, and magnetic susceptibility. The gamma-Fe2O3 nanoparticles are coated and the PAn chains are doped by anionic surfactants of omega-methoxypoly(ethylene glycol) phosphate (PEOPA), 4-dodecylbenzenesulfonic acid (DBSA), and 10-camphorsulfonic acid (CSA). Both the coated gamma-Fe2O3 and the doped PAn are soluble in common organic solvents, and casting of the homogeneous solutions gives free-standing nanocomposite films with gamma-Fe2O3 contents up to similar to 50 wt %. The morphology of the gamma-Fe2O3 nanoparticles are characterized by transmission electron microscopy, UV-vis spectroscopy, and X-ray diffractometry. The gamma-Fe2O3/PAn films prepared from chloroform/m-cresol solutions of DBSA-coated gamma-Fe2O3 and CSA-doped PAn are conductive (sigma = 82-237 S/cm) and superpapamagnetic, exhibiting no hysteresis at room temperature. The zero-field-cooled magnetization experiment reveals that the nanocomposite containing 20.8 wt % gamma-Fe2O3 has a blocking temperature (T-b) in the temperature region of 63-83 K.

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.

Physical diffusion and electron-transfer dynamics of electroactive solutes in polymer electrolytes .2. Effect of the ionic size of supporting electrolytes

The diffusion coefficients(D-app) and the heterogeneous electron-transfer rate constants(k(s)) for ferrocene in MPEG/salt electrolytes were determined by using steady-state voltammetry. The temperature dependence of the two parameters obeys the Arrhenius equation. The effect of the ionic size of six supporting electrolytes on diffusion and electron transfer dynamics of ferrocene was discussed.

The conductivity behavior of a polymer gel electrolyte

A new kind of polymer gel electrolyte which is composed of polytriethylene glycol dimethacrylate(PTREGD), propylene carbonate(PC) and LiPF6 has been prepared by thermal polymerization. The conductivity was measured as a function of temperature, and it was found that the Arrhenius equation was held very well through out the salt concentration studied. Maximum room temperature conductivity of 4.95 x 10(-4) S/cm, as well as a minimum activation energy value of 18.90 kJ/mol were obtained at the same salt concentration of 0.22 mol/L.

Studies on the electrical conductivity of carbon black filled polymers

The conductivity mechanism for a carbon black (CB) filled high-density polyethylene (HDPE) compound was investigated in this work. From the experimental results obtained, it can be seen that the relation between electrical current density (J) and applied voltage across the sample (V) coincides with Simmons's equation (i.e., the electrical resistivity of the compound decreases with the applied voltage, especially at the critical voltage). The minimum electrical resistivity occurs near the glass transition temperature (T-g) of HDPE (198 K). It can be concluded that electron tunneling is an important mechanism and a dominant transport process in the HDPE/CB composite. A new model of carbon black dispersion in the matrix was established, and the resistivity was calculated by using percolation and quantum mechanical theories. (C) 1996 John Wiley & Sons, Inc.

SYNTHESIS AND X-RAY STRUCTURE OF A SEMICONDUCTING ORGANOMETALLIC SALT [FECP(TOL)](2)[NI(MNT)(2)]

The compound [FeCp(Tol)](2)[Ni(mnt)(2)] has been prepared from [FeCp(Tol)]AlCl4 and Na-2[Ni(mnt)(2)]. This new organometallic radical ionic salt has been characterized by elemental analysis, IR, H-1 NMR and mass spectroscopy. The X-ray structure of the compound shows there are segregated cation and anion stacks in the perpendicular directions, The molecular anions form a zig-zag stacking along the b axis, and between every two neighbouring anion planes a methyl group of the cation is inserted. This gives rise to a long spacing of 6.87 Angstrom, between the anion planes. The cations stack along the c axis, with the closest spacing of 3.457 Angstrom between the cyclopentadienyl plane and the neighbouring toluene plane, which is shorter than the sum of Van der Wall's radii. Conductivity measurements showed the compound as a semiconductor with a room temperature conductivity of 1.6 X 10(-4) Scm(-1).

Study on new comb polymer electrolyte(III)

A new solid polymer electrolyte has been prepared using NaClO4 and a comb-branch polymer with oligo(ethylene oxide) side chains. The thermal and ionic conductive properties of the electrolytes were investigated. The profile of conductivity at various temperatures follows the VTF plots.

INFLUENCE OF IONIC SUBSTITUTION ON THE MAGNETIC-BEHAVIOR OF Y2CU2O5

The influence of the substitution of Cu or O by various elements on the magnetic properties of Y2Cu2O5 has been studied. The substitution of Cu by metal ions with unpaired d electrons (M = Co2+, Ni2+) makes the superexchange in Cu2O8 chains stronger, but

EFFECTS OF DOPANT AND SOLVENT ON THE PROPERTIES OF POLYPYRROLE - INVESTIGATIONS WITH CYCLIC VOLTAMMETRY AND ELECTROCHEMICALLY INSITU CONDUCTIVITY

A new method for electrochemically in situ conductivity measurements based on a reusable glassy carbon disc carbon fibre array double electrode is described. Using this technique and cyclic voltammetry, we have investigated the effects of the doping anion and solvent on the electrochemical properties of polypyrrole film. The electroactivity and potential dependent conductivity of polypyrrole film are strongly affected by solvent and the doping anion's solubility in the solvent, and also by the history of electrochemical treatments in different electrolyte solutions. It is very interesting that NO3-doped polypyrrole can completely keep its conducting state (doped state) at a reasonably negative potential (eg -0.8 V vs. sce) in acetonitrile solutions.

INSITU CONDUCTIVITY ELECTROCHEMISTRY OF CONDUCTIVE POLYMERS - POLY(3-METHYLTHIOPHENE) AND POLYTHIOPHENE

In situ monitoring of conductivity and potential response of conductive polymers during electrochemical process had been described. A renewable carbon fibre array ring-glassy carbon disk electrode was used for this purpose. Poly(3-methylthiophene) and polythiophene were investigated with this method, and some 5 orders in magnitude of conductivity changes were observed during the electrochemical redox process.

Thermal conductivity of graded spherical composites with contact resistance

The effective thermal conductivity of graded composites with contact resistance on the inclusion surface is investigated. As an example, we have considered the graded composite media with a spherical particle embedded in a homogeneous matrix, where the thermal conductivity of spherical inclusion is an exponential function k(i) = c exp(betar) (where r is the inside distance of a point in particle from the center of the spherical particle in a spherical coordinate). For both heat contact resistance and perfect contact cases, we have given a reasonable effective medium approximation to calculate the effective conductivity. (C) 2003 Elsevier B.V. All rights reserved.