The electrical conductivity of solid alkali hydroxides

Measurements of the electrical conductivity of RbOH and NaOH confirm the proposed proton conduction mechanism previously reported for KOH and CsOH. The cubic high-temperature phases of Na-, K-, Rb-, and CsOH (“rotator phases”) with free-rotating OH^?-ions have an enhanced electrical conductivity caused by a Grotthus-type conduction mechanism.     

The electrical conductivity of colloidal tungstic acid

Colloid and Polymer Science - It has been observed that during the dilution of tungstic acid the pH value varies and the variation becomes slow with increasing dilution and after a certain stage it...     

The preparation of tetracyanonickelates showing electrical conductivity

The tetracyanonickelates Ni(NH₃)₂Ni(CN)₄·1.9 H₂O (1), Ni(NH₃)_1.65(C₄H₈O₂)_0.2Ni(CN)₄·0.8 C₄H₈O₂·0.35 H₂O (2) and Ni(en)₃Ni(CN)₄·H₂O (3) exhibit, after contact with a solution of iodine (I₂/KI), appreciable weight gains. According to thermal analysis, IR spectra and chemical analysis the new products contain intercalated iodine and iodides with the highest iodine content found in the product formed from (3). The results of high frequency conductance measurements of this product showed the highest value of electrical conductivity (10^–6 S cm^–1). Other compounds show relatively low values of (10^–8–10^–11 S cm^–1).The iodine together with its iodide and polyiodide forms enters host (3) as an intercalated species. The iodide and polyiodide forms are formed during the initial redox reactions between the NH group of the ethylenediamine and the iodine.     

The electrical conductivity of chromium trioxide and its suboxides

The electrical conductivity of CrO₃ and seven samples between CrO₃ and Cr₂O₃ is measured between room temperature and the temperature of preparation of the corresponding sample using an AC circuit. CrO₃ is found to be a semiconductor having a resistance of the order of 10⁶ Ω when completely dried by heating to 100°C under a vacuum of 10^?3mm Hg. Cr₂O₃ gives a resistance of the order of l0⁵–l0³ Ω in the temperature range 25–370°C. The samples in between possess values ranging between 10⁵ and 10⁴ Ω. The activation energies are interpreted as being due to the extrinsic range.     

D.C. electrical conductivity and conduction mechanism of some azo sulfonyl quinoline ligands and uranyl complexes

Supramolecular coordination of dioxouranium(VI) heterochelates 5-sulphono-7-(4'-X phenylazo)-8-hydroxyquinoline HL(n) (n=1, X=CH(3); n=2, X=H; n=3, X=Cl; n=4, X=NO(2)) have been prepared and characterized with various physico-chemical techniques. The infrared spectral studies showed a monobasic bidentate behavior with the oxygen and azonitrogen donor system. The temperature dependence of the D.C. electrical conductivity of HL(n) ligands and their uranyl complexes has been studied in the temperature range 305-415 K. The thermal activation energies E(a) for HL(n) compounds were found to be in the range 0.44-0.9 eV depending on the nature of the substituent X. The complexation process decreased E(a) values to the range 0.043-045 eV. The electrical conduction mechanism has been investigated for all samples under investigation. It was found to obey the variable range hopping mechanism (VRH).     

The mechanism of electrical conductivity along polyhalide chains

A theoretical study of possible mechanisms for electrical conduction along polyhalide chains [X⁻₃ ]_∞ is presented. The proposed steps are the reduction of an X⁻₃ ion to X²⁻₃ ; subsequent migration of a halide ion from the X²⁻₃ unit to its nearest ne no substantial barrier; electron transfer from an elongated X²⁻₃ to its neighboring X²⁻₃ ; oxidation of an X²⁻₄ species t the backmigration of a halogen atom. The non-existence of a barrier for the halide ion transfer in an isolated chain can be elucidated with the help of tight-binding band calculations on the bulk and by ab initio pseudopotential calculations in the local region, where species like X⁻₂,X²⁻₄ and X⁻₄ might form as intermediates. The activation in the conduction process should therefor from the steps which take place at the electrodes or from interactions with the cationic sublattice in the solid.     

Preparation and electrical conductivity of organoheterobimetallic-maleonitriledithiolates

The new complexes [PhHg]₂[M(mnt)₂] [M = Ni^II, Cu^II, Zn^II or Pd^II; mnt^2– = 1,2-dicyano-1,2-ethylenedithiolate (maleonitriledithiolate)] have been characterized spectroscopically and magnetically and their solid phase conductivity measured. All compounds exhibit solid phase _rt in the 1.29 × 10^–12–5.68 × 10^–10 S cm^–1 range and semiconduct in the 313–383 K range.     

ESR and electrical conduction in polypropiolamide

ESR and electrical conductivity measurements have been made on a recently prepared polymer, polypropiolamide. The polymer was obtained as a fine powder which exhibited a nearly Lorentzian line with a width between derivative maxima of 5.2 ± 0.1 gauss and a g value of 2.0036 ± 0.0005. The signal intensity increased with increasing molecular weight. The signal was retained in a dilute solution in formic acid with a slight narrowing of the line. Permanent changes were produced in the spectra at room temperature by heat treatments of the polymer at temperatures up to 800°K. The changes were similar for samples sealed in tubes containing air, dry nitrogen gas and a vacuum of 3 × 10^?5 mm of Hg. Spectra obtained at temperatures up to 500°K showed no dependence on the presence or absence of oxygen in the ambient atmosphere. The deresistance of pressed pellets of the polymer was measured in the temperature range 450°K to 525°K, and the results were described by the relation R = R₀c^E/kT. The activation energy E had a value of 1.2 ± 0.2 ev and the resistivity at 500°K was approximately 10¹³ ohm-em. The ESR signal is attributed to an intrinsic property of the polymer which is associated with a conjugated bond system along the polymer backbone. Neither the activation energy nor the magnitude of the resistivity suggest that the delocalized electrons associated with the conjugated bond system have produced unusual electrical characteristics in the polymer.     

The electrical conductivity of polymer blends filled with carbon-black

The electrical conductivity of natural rubber/polyethylene blends filled with carbon-black is much higher than those of the individual components at the same loading level. This effect cannot be explained by a higher affinity of carbon-black for one component of the blend.     

Fluorination and electrical conductivity of BN nanotubes

Fluorination of BN nanotubes has been performed using a catalytic growth method, which leads to the appearance of markedly curved fluorine-doped BN sheets and converts originally insulating BN nanotubes to semiconductors, as confirmed by the comparative electron transport four-probe measurements on doped and undoped individual BN nanotubes.     

ESR and electrical conduction in pyrolyzed polyimides

Electrical conductivity and electron spin resonance (ESR) of pyrolyzed polyimides change drastically in air after passage of a characteristic time, which depends on the temperature and time of pyrolysis. Samples must be kept from air throughout the measurements. ESR and resistivity measurements in vacuum show that there are two types of magnetic species: localized and delocalized. A. variable-range hopping model is proposed as a possible mechanism for conduction.     

The electrical conductivity of poly-p-xylylene + CdS nanocomposites

The dependence of electrical conductivity on the concentration of CdS (c) and temperature (T) over the temperature range 10–300 K was studied for poly-p-xylylene-CdS (PPX + CdS) nanocomposites prepared by solid-state cryochemical synthesis. The results were discussed in terms of the heterogeneous conductivity model including various charge transfer mechanisms in various nanocomposite regions. Under the illumination of a film with c > 11 vol % by a daylight lamp, the conductivity increased, and the σ(T) dependence was metallic in character at low temperatures. The photoconductivity of films at larger concentrations c was caused by the appearance of photoexcited electrons in CdS nanoparticles, the separation of charges at the nanoparticle-matrix boundary, and percolation effects in films. The PPX matrix was shown to actively participate in electrical conductivity; electrons in this matrix jumped between phenyl rings. The experimental dependence of dark conductivity σ(T) at temperatures from 150 to 300 K was analyzed using the Mott hopping conductivity model with variable jump lengths. The main points of the Mott theory of hopping conductivity were discussed. Original Russian Text ? I.A. Misurkin, S.V. Titov, T.S. Zhuravleva, I.V. Klimenko, S.A. Zav’yalov, E.I. Grigor’ev, S.N. Chvalun, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 3, pp. 534–540.     

The electrical conductivity of doped oligo[aromatic diimidoselenide]

DC electrical conductivity of oligo[aromatic diimidoselenide] is studied in the temperature range 300-500 K after doping. The dopants used are I₂, FeCl₃, ZnCl₂, NaClO₄ and CuSO₄. Doping is done by mixing with 10% of the dopant, and by chemical doping. The DC electrical conductivity of the two types of doped materials is measured, compared and results interpreted. A trend of high DC electrical conductivity in the case of chemical doping especially with I₂ has been noticed. A conduction of 10⁻⁷ S cm⁻¹ is obtained at ambient or higher temperatures. This is related to a charge transfer complex formation between the oligomers and I₂. The complexation is confirmed from the electronic spectra of the chemically doped materials which showed a decrease in the π-π^* energy absorption bands and an increase in the n-π^* energy absorption bands.     

Phenyl thiazyl compounds: Synthesis and electrical conductivity

A series of substituted phenylene-dithio-bis(phenyldithiazyl) (PDBPD) and phenylthiophenyldithiazyl (PTPD) compounds have been synthesized utilizing the facile reaction between N-trimethyl silylimides and aromatic sulfenyl chlorides. The compounds are insulators with conductivities of 10^?8–10^?12 (Ω cm)^?1. However, they can be oxidized with Br₂ to conductivities of 10^?3–10^?5 (Ω cm)^?1 for pressed pellets. Electron donating and withdrawing substituents on the phenyl ring markedly alter the electrical transport properties. While PTPD compounds are soluble in many solvents, the PDBPD derivatives are only sparingly soluble.     

Relaxation phenomena and electrical conductivity of some polymeric films

Electrical conduction in sandwich samples of polyacrylonitrile (PAN) or copolymer of acrylonitrile with butadiene between silver has been studied, measuring the dependence of current on the applied field, temperature and time. The conduction mechanism depends on the polymer type. A polarization contribution is suggested in the conduction mechanism at high temperatures, besides Schottky emission in the case of PAN and the simple carrier jump model in the case of NBR at room temperature. The temporal current variation is explained in terms of dipole orientation. The mobility and charge carrier density are influenced by the applied field, temperature and film thickness.     

Preparation and characterization of polyaniline with high electrical conductivity

In the present paper, polyaniline (PANI) was polymerized by ammonium persulphate using a chemically oxidative process under mild tempertures ranging from ?5–20°C. Electrical conductivity of as synthesized PANI got enhanced gradually owing to the increase in molecular weight and crystallinity with decrease in synthesis temperature. Extraction with tetrahydrofuran (THF) was employed as the purification method of emeraldine base (EB) to enhance the electrical conductivity of PANI effectively attributed to the removal of the low molecular weight fractions and defective molecular chains. Methanesulfonic acid (MSA) was used to dope EB due to its strong acidity and small molecular size, and the amount of dopant versus EB was also optimized. Using a novel “synergistic doping” process with m‐cresol, electrical conductivity of PANI is further enhanced owing to more regular molecular chains which resulted in better interchain charge carriers' conduction. The emeraldine salts obtained finally have high electrical conductivity reaching up to 32.5 S cm^?1, which is much higher than that of the conventionally synthesized sample reported previously. Copyright © 2008 John Wiley & Sons, Ltd.     

Thermal diffusivity and electrical conductivity of electropolymerized polypyrrole films

This article presents measurement of thermal diffusivity and electrical conductivity of polypyrrole films prepared by electropolymerization. Thermal diffusivity was measured by laser radiometry (former flash radiometry). Electrical conductivity was determined by a conventional four-probe method. Increase of thermal diffusivity is observed when increasing the supporting electrolyte concentration, which is also shared with the increase of electrical conductivity. Both thermal diffusivity and electrical conductivity significantly depended on the types of counter anion incorporating into polymer bulk. Thermal diffusivity of polypyrrole film is larger than that for common nonelectrical conductive polymers. Temperature profile of thermal diffusivity for as-grown polypyrrole films shows that thermal diffusivity increases with increasing temperature (first running profile), whereas remeasured temperature profile of thermal diffusivity (second or third running profiles) shows the decrease of thermal diffusivity with increasing temperature. Electrical conductivity monotonically increases until the significant decrease of it occurs at the temperature above 130°C. Investigation of these temperature profiles of thermal diffusivity and electrical conductivity has been made by corresponding to thermal analysis data. © 1994 John Wiley & Sons, Inc.     

Measurements of electrical conductivity in solid bromine and iodine

Measurements of the electrical conductivity were performed with bromine and iodine in the liquid and the solid states, both containing low concentrations of the corresponding halide ions. In bromine the specific conductivity increases dramatically upon solidification and in iodine it changes only slightly. In both systems the conductivity in the solid is rather high, with remarkably low temperature coefficients, pointing to an unusual mechanism of conduction (of the Grotthuss type) requiring very little movement of the heavy nuclei while the charge is transferred. In mixtures of bromine with a small amount of nitrobenzene (NB) an equivalent conductivity as high as 12 cm² mol^?1 Ω^?1 was observed at ?25°C. In iodine the specific conductivity reached a value of about 0.01 Ω^?1 cm^?1 at 100°C. The energy of activation for conduction in bromine down to ?40°C was found to be about 23 kJ mol^?1, increasing sharply below this temperature. In iodine, values of about 21–27 kJ mol^?1 were observed over the whole temperature range measured.     

Measurement of viscosity and electrical conductivity and a thermodynamic model

According to the need of industrial design and application of new desulfurization technique, we determine viscosities and electrical conductivities of dilute SO₂ mixture gas in dimethyl sulfoxide mixture absorbents, and establish a thermodynamic model based on experimental data. The viscosities and electrical conductivities calculated by the model show good agreement with experimental data.