Electrical conduction in copper vanadate

A.C. and d.c. electrical conductivities, thermoelectric power and dielectric constant of copper vanadate (CuV₂O₆) have been measured in the temperature range 300–1000 K in order to discuss the electrical conduction in the compound. The extrinsic conduction, which takes place below 500 K, has been explained by small polaron hopping mechanism while intrinsic conduction, which takes place above 500 K, has been explained by large polaron band mechanism in view of the values of activation energy and charge carrier mobility in the temperature ranges 300–500 K and 500–1000 K.     

Electrical conduction in ordered defect compounds

A comparative study of the temperature dependence of electrical resistivity, carrier concentration and carrier mobility of the Ordered Defect Compounds (ODCs) CuIn₃Se₅, CuIn₃Te₅, and CuIn₅Te₈ with their corresponding normal 1:1:2 phase is reported. Relatively lower carrier concentration and higher activation energy observed in ODCs is explained on the basis that shallow acceptor or donor levels observed in 1:1:2 phase are partially annihilated in these compounds due to attractive interaction between V_Cu⁻¹ and In_Cu⁺² defect pair. In the activation regime, the mobility is explained by taking into account a scattering mechanism of the charge carriers with donor–acceptor defect pairs. The electrical data at lower temperatures is explained with the existing theoretical expression for the nearest neighbor hopping conduction mechanism.     

Electrical conduction in cadmium germanate glasses

Preliminary conductivity data are reported for a series of novel cadmium germanate glass compositions. All systems studied are electronic conductors with small activation energies. The highest in CdO-content sample, 0.56CdO·0.44GeO₂, is found to exhibit σ_300K≊100 mho/cm. Correlations are attempted between the transport properties and the structural characteristics of these glasses.     

Electrical conduction in sodium nitrate crystals

The need for study of electrical transport in non-alkali halide ionic crystals is emphasized. Non-cubic systems with less simple structure present interesting anisotropic properties and problems of spacial hindrance. Our experience in this direction is summarized with detailed reference to the results on sodium nitrate crystal which is being investigated in our laboratory in some detail.     

Electrical conduction of emulsion explosives

Results of experiments to obtain a spatial distribution of electrical conduction of emulsion explosives for different content of a sensitizer are presented.     

Electrical conduction in coevaporated antimony trisulphide films

Antimony trisulphide films were prepared by the three temperature method. The temperature dependence of conductivity for films prepared at different substrate temperatures were measured. The I–V characteristics of the Sb-Sb₂S₃-Sb systems studied showed a space charge limited conduction indicating a I ∝ V² /d³ dependence. The trap density and the trap energy level were determined.     

Electrical conduction in binary macrosystems: General rules

The conductivity of a macroscopically disordered graphite-paraffin system as a function of the graphite content and temperature is studied. It is shown that the properties of the heterosystem differ essentially from those of its components. Experimental data obtained are explained in terms of the percolation theory and concepts of fractal-structure objects.     

Electrical conduction in sputtered Si:Al films

The d.c. electrical resistivity ?(x, T) has been measured for a series of granular Si_xAl_1?x sputtered films for 0.25 < x < 0.62 and 4K < T < 300 K. Three separate behaviours are identified in ?(x, T) corresponding to extrinsic activated semiconduction, metallic conduction and electron localisation.     

Electrical conduction in Cu/Mn multilayer films

Metallic superlattices of copper and manganese have been synthesized on glass and mica substrates by a sequential evaporation technique. The electrical resistivity and the temperature coefficient of resistance (TCR) of layered Cu/Mn has been studied for various thicknesses (d) in the range 2–6 nm by varying the number of double layers (n) from 5–35. The transition from a negative to positive TCR has been observed ford >5 nm. The thickness dependence of room temperature resistivity ( _RT) and TCR shows oscillatory behaviour.     

Electrical conduction and size effect in bismuth films

The size effect on electrical conduction is observed in bismuth films in the region of film thickness above 2000 Å. Applying Fuchs-Sondheimer theory and assuming specularity parameterp = 0·8, the value of bulk resistivity and mean free path are obtained as 6·692 × 10⁴ ohm-cm and 6000 Å respectively.     

Electrical conduction in copper-poly(vinyl-alcohol) composites

The temperature dependence of d.c. conductivity was investigated in composites of copper (Cu) and poly(vinyl-alcohol) (PVA) prepared by compression of a mixture. A minimum appeared in the conductivity vs reciprocal temperature curves, which is discussed as a result of the competition between hopping and thermally activated modes of conduction. It was also found that the conduction of Cu-PVA composites obeys a percolation model. Dependences of reverse current vs voltage were investigated and discussed in terms of a clean-up effect of charge carriers. Quantitative analysis was carried out to determine the activation energy, drift mobility and carrier concentration.     

Specific features of photo-and electrical conduction in manganese germanium garnets

The specific features of photo-and electrical conduction in manganese germanium garnet crystals are investigated in the temperature range 4.2–370 K for the first time. Under exposure of samples with ohmic contacts to visible light, the photocurrent in these samples is observed only at high temperatures. The characteristic times of the photocurrent rise differ from those of photocurrent relaxation after the light is switched off. The inference is made that the photo-and electrical conduction is determined by the electrical recharging of manganese ions. The generation and transport of charge carriers are controlled by centers with electrical inhomogeneities and shallow attachment levels.     

Electrical conduction of SnBi4Se7

Polycrystalline samples of Bi₂Se₃ and stoichiometric ternary compounds in the quasi-binary system SnSe-Bi₂Se₃ were characterized by measurements of temperature and field dependence of electrical conductivity. The current density–electric field characteristics were found to be non-linear, especially when the applied electric field exceeds a certain value which is dependent on the temperature T. Furthermore, the electrical conductivity can be enhanced by the applied electric field. The characteristic length a(T) seemed to be enhanced with increasing temperature. Electrical conductivity measurements elucidated the semiconducting behaviour of both compounds, especially when the temperature of measurement exceeds a certain value for SnBi₄Se₇, and hopping and band type conduction are dominant at low and high ranges of temperature, respectively. Below 200 K, the electrical conductivity of SnBi₄Se₇ decreases with increasing temperature. Meanwhile, additional scattering and hopping seemed to characterize the behaviour of SnBi₄Se₇ due to the Sn doping of Bi₂Se₃ resulting in additional states at the Fermi level. PACS 72.20.-i; 72.15.-v     

极性分子型电流变液导电机理研究

极性分子型电流变液是一种新型的电流变材料.其介电颗粒上吸附极性分子,极性分子在颗粒间强局域电场作用下发生取向是产生巨电流变效应的关键.通过对Ca—Ti—O(CTO)体系极性分子型电流变液电流密度的测量发现,其导电行为遵从Poole-Frenkel效应的规律,这是极性分子型电流变液的重要特征之一.而500 ℃处理过的CTO粉体不含极性分子,所配制的电流变液无巨电流变效应,其电流密度随外电场强度近似地呈线性关系,显示出传统电流变液特性.     

Electrical conduction and dielectric studies of ZnO pellets

A series of Zinc Oxide pellets sintered at different temperatures was studied by means of dielectric spectroscopy in the wide frequency range of 1–10⁶ Hz and temperature interval from −100 °C to 30 °C. Electrical conductivity was analysed using Jonsher's universal power law, and the values of s were found to decrease with the increase in temperature, which agrees well with the correlation barrier hopping (CBH) model.     

Electrical conduction measurement of thiol modified DNA molecules

We present a novel transport measurement of 60 base pairs of poly(dG)–poly(dC) DNA molecules. Thiol-terminated DNA molecules are chemically anchored at the surface of a Au nanoparticle and this DNA attached Au nanoparticle is self-trapped in between Au nanoelectrodes to make an electrical conduction channel. It provides an automatic electrical conduction channel consisting of electrode–DNA–nanoparticle–DNA–electrode. Due to robust bonding of thiol and Au, this transport channel is stable and reliable. The current–voltage characteristics measured from our device show a nonlinear behavior with voltage gaps comparable to previous experiment using the same molecules.     

Electrical properties and conduction mechanism in the sodium nickel diphosphate

The Na_3.6Ni_2.2(P₂O₇)₂ compound was obtained by the conventional solid-state reaction. The sample was characterized by X-ray powder diffraction and vibrational and impedance spectroscopy. The AC electrical conductivity and the dielectric relaxation properties of this compound have been investigated by means of impedance spectroscopy measurements over a wide range of frequencies and temperatures, 209 kHz–1 MHz and 564–729 K, respectively. Dielectric data were analyzed using complex electrical modulus M* at various temperatures. The peak positions ω _m of M″ spectra shift toward higher frequencies with increase in temperature. The AC conductivity data fulfill the power law. Application of the correlated barrier hopping model revealed that the ionic conduction takes place by single-polaron and bipolaron hopping processes.