Activation Energy Of Electrical Conductivity Research Articles

Synthesis of (PVA–PEG–PVP–ZrO2) nanocomposites for energy release and gamma shielding applications

The new type of polymer blend-nanoparticle nanocomposites of (PVA–PEG–PVP) with zirconium oxide nanoparticles for energy storage and release application and gamma shielding application has been investigated. The D.C electrical properties of (PVA–PEG–PVP–ZrO2) nanocomposites with different concentrations zirconium oxide nanoparticles were measured with different temperature range. The results show the conductivity of (PVA–PEG–PVP–ZrO2) nanocomposites is increased with the increase of zirconium oxide nanoparticles concentration. The activation energy of electrical conductivity of (PVA–PEG–PVP–ZrO2) nanocomposites is decreased with the increase of zirconium oxide nanoparticles weight percentages. The results of applications show that enhancement of efficiency for energy storage and release by using (PVA–PEG–PVP–ZrO2) nanocomposites and the (PVA–PEG–PVP–ZrO2) nanocomposites have higher attenuation coefficients for gamma radiation.

Mixed modifier effect in lithium‐calcium borosilicate glasses

AbstractThe mixed modifier effect (MME) in the lithium‐calcium borosilicate glasses, which have a composition of 0.4[(1−x)Li2O–xCaO]–0.6[(1−y)B2O3–ySiO2] with x in the range of 0~1 and y in the range of 0.33~0.83, is investigated. The MME manifests itself as a positive deviation from linearity in the activation energy of electrical conductivity (Eaσ) and as a negative deviation from linearity in the fraction of four‐coordinated boron (N4), glass transition temperature (Tg), dilatometric softening temperature (Td), Vickers microhardness (Hv), dielectric constant (ε), and dielectric loss (tanδ). Moreover, the deviation, which exhibits a maximum at [CaO]/([CaO]+[Li2O])=0.5, is enhanced with increasing [SiO2]/[B2O3] ratio in the glass network. The observed MME in Tg, Td, and Hv are attributed to the bond weakening in the network; however, the MME in ε, tanδ, and Eaσ are caused by the obstruction of modifier transport in the glass network.

Chitosan hydrogel-based electrolyte for clean and biodegradable batteries: energetic and conductometric studies

ABSTRACTMeasurements of voltages generated in clean and biodegradable batteries using lithium-chitosan as electrolyte, carbon and nickel as electrodes, were reported. They produced small amounts of energy providing environment was preserved. The energy smallness was argued by conductivity measurements. The concentration and temperature dependences were undertaken. These measurements were carried out from 0.0005 to 1.0 mol dm−3 in the temperature range 258–323 K, and were compared to glycerol, being clean viscous solvent. The purpose was to substitute toxic solvents currently used, by clean and biodegradable solvents having good performances. The results were analysed with Debye–Huckel–Onsager law at low concentrations and Quasi–Lattice Model at moderate and higher concentrations. The temperature dependence of conductivity was also described using Vogel–Tamman–Fulcher equation. By comparing it to Arrhenius theory, very interesting parameters, such as electrical conductivity infinite dilution, activation energy and Vogel temperature, corresponding to glass transition temperature were extracted from the fit of experimental data.

Improved DC performance of crosslinked polyethylene insulation depending on a higher purity

Super-clean crosslinked polyethylene (XLPE) has been widely used in DC power cables. In order to understand the nature of purity dependence of electrical insulation performance, two kinds of insulating XLPE materials used in AC and DC high voltage cables, whose abbreviation were AC-XLPE and DC-XLPE respectively, were investigated in this paper. The results showed that DC-XLPE had a relative higher DC electrical conductivity and relative lower thermal activation energy than AC-XLPE, which was governed by the trap characteristics. The thermal activation energies could match the energy depths of the bulk deep traps calculated by thermal stimulated current. Both positive and negative charges can be found in AC-XLPE while there were only positive charges in DC-XLPE. Meanwhile, DC-XLPE showed higher electric breakdown strength than AC-XLPE. It was proposed that the improved DC insulation performance of DC-XLPE was closely related to its higher purity. The Fourier transform infrared spectroscopy results showed AC-XLPE contained more polar groups such as carbonyl groups than DC-XPLE, which were caused by antioxidants. The oxidative induction times verified a higher content of antioxidant in AC-XLPE. X-ray diffraction showed little difference of crystallinity between two samples, but DC-XLPE exhibited a larger spherulite size. As a result, it is suggested that more efforts should be made to achieve higher purity of XLPE in HVDC insulation.

Thermal and electrical properties of Ce0.8-x Pr x Sm0.2O2-δ electrolyte materials for IT-SOFC applications

Praseodymium and samarium co-doped ceria-based electrolyte materials Ce0.8-x Pr x Sm0.2O2-δ (0≤ x ≤0.06) were prepared by using the sol–gel method. The phase identification and morphology were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The thermal expansion properties were studied by using a dilatometric technique, and it was observed that the thermal expansion coefficient (TEC) varies linearly with temperature for all the samples in the temperature range 30–1000 °C. The electrical conductivity was studied using impedance spectroscopy, and it was observed that the Ce0.74Pr0.06Sm0.2O2-δ composition showed higher electrical conductivity and lower activation energy, and constant phase element (CPE) equivalent circuit was fitted at 450 °C. This composition, because of its unique properties, may find applications in the intermediate-temperature solid oxide fuel cell (IT-SOFC) as an electrolyte.

Maximum on the Electrical Conductivity Polytherm of Molten TeCl4

Abstract The electrical conductivity of molten TeCl4 was measured up to 761K, i.e. 106 degrees above the normal boiling point of the salt. For the first time it was found that TeCl4 electrical conductivity polytherm has a maximum. It was recorded at 705K (κ max=0.245 Sm/cm), whereupon the conductivity decreases as the temperature rises. The activation energy of electrical conductivity was calculated.

Cationically Substituted Bi0.7Fe0.3OCl Nanosheets as Li Ion Battery Anodes.

Cation substitution of Bi3+ with Fe3+ in BiOCl leads to the formation of ionically layered Bi0.7Fe0.3OCl nanosheets. The synthesis follows a hydrolysis route using bismuth(III) nitrate and iron(III) chloride, followed by postannealing at 500 °C. Room temperature electrical conductivity improves from 6.11 × 10-8 S/m for BiOCl to 6.80 × 10-7 S/m for Bi0.7Fe0.3OCl. Correspondingly, the activation energy for electrical conduction reduces from 862 meV for pure BiOCl to 310 meV for Bi0.7Fe0.3OCl. These data suggest improved charge mobility in Bi0.7Fe0.3OCl nanosheets. Density functional theory calculations confirm this behavior by predicting a high density of states near the Fermi level for Bi0.7Fe0.3OCl. The improvement in electrical conductivity is exploited in the electrochemical performance of Bi0.7Fe0.3OCl nanosheets. The insertion capacity of Li+ ions shows an increase of 2.5×, from 215 mAh·.g-1 for undoped BiOCl to 542 mAh·g-1 for Bi0.7Fe0.3OCl after 50 cycles at a current density of 50 mA·g-1. Thus, the direct substitution of Bi3+ sites with Fe3+ in BiOCl results in nanosheets of an ionically layered ternary semiconductor compound which is attractive for Li ion battery anode applications.

Enhanced ionic conductivity of scandia-ceria-stabilized-zirconia (10Sc1CeSZ) electrolyte synthesized by the microwave-assisted glycine nitrate process

Scandia-stabilized-zirconia is a potential zirconia-based electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, the properties of zirconia co-doped with 10mol% Sc and 1mol% Ce (scandia-ceria-stabilized-zirconia, 10Sc1CeSZ) electrolyte synthesized by the microwave-assisted glycine nitrate process (MW-GNP) were determined. The effects of microwave heating on the sintering temperature, microstructure, densification and ionic conductivity of the 10Sc1CeSZ electrolyte were evaluated. The phase identification, microstructure and specific surface area of the prepared powder were investigated using X-ray diffraction, transmission electron microscopy and the Brunauer-Emmett-Teller technique, respectively. Using microwave heating, a single cubic-phase powder was produced with nanosized crystallites (19.2nm) and a high specific surface area (16m2/g). It was found that the relative density, porosity and total ionic conductivity of the 10Sc1CeSZ electrolyte are remarkably influenced by the powder processing method and the sintering temperature. The pellet sintered at 1400°C exhibited a maximum ionic conductivity of 0.184S/cm at 800°C. This is the highest conductivity value of a scandia-stabilized-zirconia based electrolyte reported in the literature for this electrolyte type. The corresponding value of the activation energy of electrical conductivity was found to be 0.94eV in the temperature range of 500–800°C. Overall, the use of microwave heating has successfully improved the properties of the 10Sc1CeSZ electrolyte for application in an IT-SOFC.

On the mechanism of highly efficient p-type conduction of Mg-doped ultra-wide-bandgap AlN nanostructures

Free hole concentrations up to ∼6 × 1017 cm−3 were measured in Mg-doped AlN nanowires at room-temperature, which is several orders of magnitude larger than that of previously reported AlN epilayers. Detailed studies suggest that such unusually high carrier concentrations stem from the efficient hole hopping conduction in the Mg impurity band, driven by the significantly enhanced Mg-dopant incorporation in nearly defect-free AlN nanostructures. Distinct signatures of hole hopping conduction in the Mg impurity band are observed experimentally, including a relatively small activation energy for electrical conductivity and an increase in hole mobility with increasing temperature.

Ion Conduction of BaPrO3-δ Thin Film with Mixed Valence State for SOFC Anode Electrode

The in-plane-oriented BaPrO3-δ thin film with mixed valence states has been prepared on an Al2O3 (0001) substrate by RF magnetron sputtering. The lattice constant decreases with increasing film thickness. The thin film has the mixed valence states of Pr4+ and Pr3+. The ~168 nm thickness film with small lattice constant exhibits high electrical conductivity and low activation energy of 0.58 eV. The thin film at wet air shows hole-ion mixed conduction and proton conduction, which is required as anode electrode of solid oxide fuel cell, at 300 °C.

Role of Sb Substitution on Electrical Properties of Se-Te Glasses

Objectives: This paper reports the influence of Sb addition on the electrical properties on bulk samples of Se80-xTe20Sbx(x=0,6, 12) glasses. Methods/Statistical Analysis: The amorphous samples have been prepared using melt quenching method and the pellets of the bulk sample of thickness 1mm and diameter 5mm has been formed using pelletiser. The I-V measurements of pellets have been recorded on Keithley electrometer in the temperature range 298-398 K. The data obtained is analysed to calculate activation energy of conduction and temperature dependent dc electrical conductivity. Findings: The observations suggest that conductivity decreases due to formation of highly crosslinked structure when Sb is added in less amount i.e. 6 at.wt% whereas on addition of Sb upto 12 at. wt. %, conductivity increases significantly due to increase in ring structure and decrease of steric hindrance in system. Earlier reports on the electrical properties of Se-Te-Sb system provided information upto 10 at. wt. % of Sb addition to Se-Te system, whereas in present study Sb is added upto 12 at.wt.% to get its influence on electrical properties of Se-Te system. Applications/Improvements: The higher content of Sb in Se-Te system increases the electrical conductivity which makes it a potential candidate for application in electronic devices.

Electrical conductivity of a silicone network upon electron irradiation: influence of formulation

In this study, the electrical conductivity of a silicone elastomer filled with inorganic fillers was investigated upon electron irradiation. Neat samples consisting of the isolated polysiloxane matrix (with no fillers) were studied in parallel to identify the filler contribution to this evolution.It was shown that exposure to 400 keV electron doses induced a decrease in electrical conductivity for both the filled and neat materials. This decrease was much more pronounced with the filled samples than with the neat ones. Moreover, the activation energy of electrical conductivity (Arrhenius behaviour) doubled in the filled case, while it varied only weakly for the neat case. In light of these results, structure–property relationships were proposed on the basis of the radiation-induced crosslink processes to which this material is subject. In the framework of electronic percolation theory, it is suggested that the radiation-induced formation of SiO3 crosslinks in the polysiloxane network and SiO4 crosslinks at filler–matrix interfaces affects the percolation path of the material, which can be simply modelled by a network of resistors in series. On one hand, their densification increases the overall resistance of the percolation path, which results in the observed decrease of effective electrical conductivity. On the other hand, the steep increase in activation energy in the filled material attributes to the SiO4 crosslinks becoming the most restrictive barrier along the percolation path.In spite of the misleading likeness of electrical conductivities in the pristine state, this study presented evidence that silicone formulation can affect the evolution of electrical properties in radiative environments. To illustrate this conclusion, the use of this material in space applications, especially when directly exposed to the radiative space environment, was discussed. The decrease in electrical conductivity was associated with a progressively increasing risk for the occurrence of electrostatic discharge and consequent spacecraft failures.

An accurate method to determine the through-plane electrical conductivity and to study transport properties in film samples

The through-plane conductivity of a film sample is critically important because it largely affects the performance of batteries, capacitors, and thermoelectric devices. In this study, we developed a modified four-probe through-plane electrical conductivity measurement method using a coaxial structure. This method is general and works for free-standing film samples. We studied different samples including a steel sheet, highly oriented pyrolytic graphite, and conducting polymers. We confirmed metallic transportation in the steel sheet and hopping transportation in graphite in the through-plane direction by conducting low temperature measurements at 100 K. In the case of a conducting polymer poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate, the conductivity anisotropic ratio decreases with increasing in-plane conductivity. Temperature dependent measurements show two distinct activation energy regimes in the through-plane direction in PEDOT/PSS but almost no change in the in-plane electrical conductivity activation energy. This could be due to additional carrier paths that occur through the more disordered region (the PSS-rich region) in the through-plane direction. We also examined the Meyer–Neldel rule in PEDOT/PSS and concluded that PEDOT/PSS follows the anti-Meyer–Neldel rule, likely due to the high carrier density in the film.

Cathode properties of sodium iron phosphate glass for sodium ion batteries

In order to clarify the possibility of cathode activity of Na2O-FeO-P2O5 glasses for sodium ion batteries, glass formation tendency, crystallization behavior, electrical conductivity as well as charge and discharge properties are examined. Glass formation in xFeO–(100-x)NaPO3 was confirmed for x≤45 by melt quenching up to 1000°C in N2 filled electric furnace. By means of electrical conductivity tests, conductivity was increased with increases of x content in xFeO–(100-x)NaPO3 and the activation energy for electrical conductivity was decreased. Charge and discharge profiles for Na anode exhibits high reversible discharge capacity as 115mAh/g at 0.1°C rate in 40FeO-60NaPO3 (30Na2O–40FeO–30P2O5) glass. The results on Raman scattering spectra suggests that glass structure is subjected to polymerized Q1 and Q2 phosphate units. And polymerized phosphates in glass cause lower density, open structure and sodium ion diffusive channels as well.

A Limiting Current Oxygen Sensor Based on LSGM as a Solid Electrolyte and LSGMN (N = Fe, Co) as a Dense Diffusion Barrier

The La0.8Sr0.2(Ga1−xCox)0.8Mg0.2O3−δ (LSGMC x = 0.05, 0.1, 0.15, 0.2, 0.25) and La0.8Sr0.2(Ga1−xFex)0.8Mg0.2O3−δ (LSGMF x = 0.1, 0.2, 0.3) samples were prepared by solid-state reaction. The structure, conductivity, thermal expansion behavior, and chemical compatibility were studied by XRD, dilatometry, and four-terminal method. A limiting current oxygen sensor was prepared with La0.8Sr0.2Ga0.83Mg0.17O2.815 as a solid electrolyte and La0.8Sr0.2(Ga0.75Co0.25)0.8Mg0.2O3−δ as a dense diffusion barrier. The oxygen-sensitive characteristic was measured at different oxygen concentrations. The results show that the phase structure of samples is cubic, except La0.8Sr0.2(Ga0.75Co0.25)0.8Mg0.2O3−δ, which has a hexagonal structure. The change in activation energy for electrical conductivity and the increase in thermal expansion coefficient are confirmed to correlate with an increasing concentration of oxygen vacancies. The limiting current oxygen sensor exhibits a good limiting current platform and the limiting current depends linearly on the oxygen concentration: IL(mA) = 12.8519 + 2.2667 \(x_{{\text{O}_{\text{2}} }}\) (mol%, 0 < \(x_{{{\text{O}}_{ 2} }}\) < 3.31) at 750 °C, IL(mA) = 14.3222 + 3.5180 \(x_{{\text{O}_{\text{2}} }}\) (mol%, 0 < \(x_{{{\text{O}}_{ 2} }}\) < 4.16) at 800 °C, and IL(mA) = 15.2872 + 5.0269\(x_{{\text{O}_{\text{2}} }}\)(mol%, 0 < \(x_{{{\text{O}}_{ 2} }}\) < 4.12) at 850 °C. The sensor has the best sensitivity at 850 °C. As the oxygen concentration increases, the interface resistance of the sensor decreases at 850 °C.

Electrical and thermoelectric properties of different compositions of Ge–Se–In thin films

The effect of temperature in the range of 300–450K and the indium content on the electrical and thermoelectric properties of Ge20Se80−xInx (0.0≤x≤24at%) chalcogenide glassy thin films have been studied. From dc electrical and thermoelectric measurements, it was observed that the activation energies for electrical conductivity (ΔE) and for thermoelectric (ΔEs) decrease while the conductivity (σ) and Seebeck coefficient (S) increase upon introducing In into the Ge–Se glasses. In contrast to the behavior obtained with Bi or Pb doping, In incorporated in Ge–Se does not lead to a p-to n-type conduction inversion. The power factor (P) which is strongly depends on both of the Seebeck coefficient and the electrical conductivity. According to the obtained results, the Ge20Se80−xInx films can be considered potential candidates for incurring high action thermoelectric materials.

Electrical Conductivity of Molten CdCl2 at Temperatures as High as 1474 K

Abstract The electrical conductivity of molten CdCl2 was measured across a wide temperature range (ΔT=628 K), from 846 K to as high as 1474 K, i.e. 241° above the normal boiling point of the salt. In previous studies, a maximum temperature of 1201 K was reached, this being 273° lower than in the present work. The activation energy of electrical conductivity was calculated.

Estimation and Structural Effect on Physicochemical Properties of Alkylimidazolium-Based Ionic Liquids with Different Anions

Ten kinds of alkylimidazolium-based aprotic ionic liquids (AILs) with hydrogen carbonate, dihydrogen phosphate, and hydrogen sulfate anions were prepared, and methods of elemental analysis, infrared spectroscopy, and proton nuclear magnetic resonance were employed to characterize the ILs, respectively. Properties such as electrical conductivity, density, dynamic viscosity, surface tension, were measured and correlated with thermodynamic and empirical equations over various temperature ranges under ambient conditions. Some significant thermodynamic parameters of the ILs were estimated. The trends of changing with temperature for the dynamic viscosity and the electrical conductivity were described by the Vogel–Fulcher–Tamman equation. The activation energies of dynamic viscosity and electrical conductivity were also calculated. Further, the structures and the energetics of the ILs ions were obtained through combining density functional theory calculations and the COSMO-RS methodology. The structural effects...

Enhanced thermoelectric properties of carbon fiber reinforced cement composites

Thermoelectric properties of carbon fiber reinforced cement composites (CFRCs) have attracted relevant interest in recent years, due to their fascinating ability for harvesting ambient energy in urban areas and roads, and to the widespread use of cement-based materials in modern society. The enhanced effect of the thin pyrolytic carbon layer (formed at the carbon fiber/cement interface) on transport and thermoelectric properties of CFRCs has been studied. It has been demonstrated that it can enhance the electrical conduction and Seebeck coefficient of CFRCs greatly, resulting in higher power factor 2.08µWm−1K−2 and higher thermoelectric figure of merit 3.11×10−3, compared to those reported in the literature and comparable to oxide thermoelectric materials. All CFRCs with pyrolytic carbon layer, exhibit typical semiconductor behavior with activation energy of electrical conduction of 0.228-0.407eV together with a high Seebeck coefficient. The calculation through Mott’s formula indicates the charge carrier density of CFRCs (1014–1016cm−3) to be much smaller than that of typical thermoelectric materials and to increase with the carbon layer thickness. CFRCs thermal conductivity is dominated by phonon thermal conductivity, which is kept at a low level by high density of micro/nano-sized defects in the cement matrix that scatter phonons and shorten their mean free path. The appropriate carrier density and mobility induced by the amorphous structure of pyrolytic carbon is primarily responsible for the high thermoelectric figure of merit.

Novel Iron Bismuth Oxychloride Nanosheets for Lithium Ion Batteries

Iron Bismuth Oxychloride nanosheets were successfully synthesized by facile hydrolysis method. The X-ray photoelectron spectroscopy (XPS) shows composition was uniformly controlled as Fe0.3Bi0.7OCl. UV-Vis spectra and cyclic voltammetry (CV) results show the band gap of nanosheets correspondingly decreased from 3.4 eV for BiOCl to 2.08 eV for Fe0.3Bi0.7OCl due to raising of the valence band edge. Activation energy for electrical conductivity reduced from 862 meV to 796 meV for BiOCl and Fe0.3Bi0.7OCl, respectively. Density functional theory calculations predict changes to the valence band and decrease in the Fermi level toward the valence band edge for the Fe0.3Bi0.7OCl nanosheets - in accordance with experimental data. Correspondingly the Li ion capacities increased from 215 mAh/g for BiOCl to 542 mAh/g for Fe0.3Bi0.7OCl after 50 cycles at the current density of 100 mA/g.