Electrical Activation Energy Research Articles

Effects of Non-Linear Thermal Radiation and Chemical Reaction on Time Dependent Flow of Williamson Nanofluid With Combine Electrical MHD and Activation Energy

The current article will present the impact of the heat and mass transfer of combine electrical MHD flow of time dependent Williamson fluid with nanoparticles by the incorporating the influences of non-linear thermal radiation and the chemical reaction through wedge shape geometry. The fluid flows past a porous stretching wedge with convected Nield boundary conditions. The several (geometrical and physical) conditions have been included to provide more practicable results. The effects of activation energy further discussed. Due to relevant similarity transformation, set of partial differential equations which is non-linear and complicated is converted into simplest system of ordinary differential equations. To obtain the desired solution, famous numerical technique (shooting) used with the help of bvp4c MATLAB coding. The variation physical quantities namely velocity, temperature, concentration of nanoparticles, local Sherwood number, coefficient of skin friction and local Nusselt number have been observed under the influence of emerging parameters. The elaborated discussion presented with graphical and tabular illustrations.

Effect of different dosage of gamma irradiation on quasi-solid-state conducting polymer electrolyte and its application as high performance dye-sensitized solar cells

ABSTRACT The nanocomposite polymer electrolyte [x (85 PVA: 10 PPy: 5 KI: I2:15 EC: 15MPII: 10 TiO2) for x = 5, 10, 15 Gy γ-ray irradiation] is prepared using the solution casting technique. Exposure of γ-ray irradiation enhanced the amorphous nature of the polymer electrolyte, is confirmed by XRD. The 15Gy γ-ray-irradiated nanocomposite polymer electrolyte has higher electrical conductivity and minimum activation energy (0.664 kJ mol−1). The EIS measurement reveals that the 15Gy γ-ray-irradiated nanocomposite polymer electrolyte incorporated DSSC shows lower Rct 1 and Rct 2 values at the counter electrode/electrolyte and photoanode/electrolyte interface, respectively. An outstanding performance is observed in the fabricated DSSCs using 15 Gy γ-ray-irradiated nanocomposite polymer electrolyte with a short circuit current density of 12.602 mA cm−2, an open-circuit voltage of 0.711 V, a fill factor of 0.535, and a photovoltaic conversion efficiency of 4.79% under the light intensity of 100 mW cm−2.

Electrical Conductivity and Thermoelectrical Parameters of Argyrodite-Type Cu7 – xPS6 – xIx Mixed Crystals

Cu7−xPS6−xIx mixed crystals were grown by the direct crystallization from a melt. The electrical conductivity is measured in the frequency range from 10 Hz to 300 kHz and in the temperature interval 293–383 K. The frequency, temperature, and compositional dependences of the electrical conductivity for Cu7−xPS6−xIx mixed crystals are studied. The measurements of thermoelectric parameters of Cu7−xPS6−xIx mixed crystals are carried out in the temperature interval 293–383 K. The compositional behaviors of the electrical conductivity, activation energy, Seebeck coefficient, and power factor are investigated. The interrelation between the structural, electrical, and thermoelectrical properties is analyzed.

Current density and thermodynamic analysis of energy optimization for double exothermic reaction of magneto-Oldroyd 8-constant material

This study analyses current density and thermodynamics second law of double reaction of a magneto-Oldroyd 8-constant liquid in a convective asymmetric cooling medium. The viscoelastic properties of the liquid are prevented from distortion by convective cooling of the flow media device which is taken to satisfy Newton’s law of cooling. The flow momentum is motivated by exothermic reaction, chemical kinetics and energized by pressure gradient in the absence of material consumption. The dimensionless leading flow equations are solved using partition weighted residual analytical technique to reveal the parameters sensitivity and impacts on the viscoelastic flow liquid, exothermic combustible heat diffusion, entropy generation and current density. The solution results are presented in tables and graphs for clear understanding of the thermophysical parameters implication on the double reaction fluid considered. As observed, the second step reaction enhances exothermic reaction that in turn support complete combustion process in an engine. An improvement of thermodynamic equilibrium through reducing material terms and Frank-Kamenetskii will minimize the entropy generation and promote thermal engineering machine performance. Current density is augmented by rising second step reaction, electric field loading and activation energy ratio.

Enhancement of optical, dielectric and transport properties of (Sm, V) co-doped ZnO system and structure-property correlations

In this work, V-doped and (Sm, V) co-doped ZnO samples have been synthesized using ball milling method followed by heat treatment. The dependence of structural, optical, electrical and dielectric properties of V:ZnO samples on the Sm doping concentration has been explored. The structural properties have been studied by means of X-ray diffraction (XRD) and Rietveld refinement. Oxidation states of the elements present in the samples are determined using X-ray photoelectron spectroscopy. Raman spectra of the samples further verified the observations obtained from XRD. The crystallite size and microstrain have been estimated from the Williamson-Hall analysis. Microstrain increases from 0.814 × 10−3 to 1.01 × 10−3 with increase in the Sm doping level. The morphology of the grains is significantly affected by the Sm doping. The enhancement of defect density with Sm doping is responsible for the observed red shift (3.29–3.19 eV) in the band gap. The frequency dependence of the dielectric properties has been studied at various fixed temperatures ranging from 25 to 350 °C. The increase in real dielectric constant with dopant content indicates the enhancement of energy storage capacity. The ac conductivity follows Jonscher's power law and it increases up to 1 mol% Sm concentration. Further increase in Sm extent leads to the decrease in ac conductivity. The impedance spectroscopy has been performed to understand electrical behavior of samples and Cole-Cole plots are fitted against the equivalent circuit model. The electrical activation energy values for conduction and relaxation vary in the range: 0.281–0.269 eV and 0.260–0.243 eV, respectively.

Influence of heterovalent substitution on structural, electrical and thermoelectric properties of Cu7-xPS6-xBrx solid solutions

Synthesis and growth of Cu7-xPS6-xBrxsolid solutions were performed. Cu7-xPS6-xBrxsolid solutions were grown by the method of direct crystallization from the melt. Impedance measurements were carried out in the range of frequencies from 10 Hz to 300 kHz and in the temperature interval 293–383 K. Temperature and frequency dependences of electrical conductivity for Cu7-xPS6-xBrxsolid solutions were studied. Thermoelectric parameters of Cu7-xPS6-xBrxsolid solutions were measured in the temperature interval 293–383 K. The compositional behavior of electrical conductivity and activation energy as well as Seebeck coefficient and power factor was analyzed. The influence of heterovalent substitution on structural, electrical and thermoelectric properties of Cu7-xPS6-xBrxsolid solutions was studied.

Tailoring the Structural and Electrical Properties of Ba–Zn–Co M-Type Hexaferrites by Lanthanum Substitution for High-Resistivity Applications

In this study, Ba0.5Zn0.2Co0.3Fe12-yLayO19 (y = 0, 0.1, 0.2, 0.3, 0.4, 0.5) nano-hexaferrites were prepared through the co-precipitation route. The synthesized powder was sintered at 1100 °C for 6 h to assist the crystallization process. The formation of single-phase hexagonal structure was confirmed by XRD. The size of prepared crystals of nano-hexaferrites was estimated in the range of 12.5–28.1 nm. The FTIR spectra also confirmed the formation of M-type hexagonal phase with the characteristic band of hexagonal structure observed at about 560 cm−1. The current voltage measurements were performed to study the electrical nature of prepared samples in the temperature range 300–900 K. At room temperature, the highest values 2 × 1011 Ω cm and 0.5 eV of electrical resistivity and activation energy, respectively, are found for the sample with La concentration y = 0.2. The enhanced dc electrical resistivity due to La substitution shows that the synthesized hexaferrites are efficient to reduce the eddy current losses for device fabrication in the high-frequency range.

Influence of Halogen Ions on Electrical, Magnetic and Shielding Properties of Some B2O3- V2O5- Na2O Glasses

Some sodium boro-vanadate glasses containing various halogen ions (chlorine, bromine and iodine) were prepared. These glasses were characterized by measuring the experimental densities, dc conductivities and volume-magnetic susceptibilities. Then the empirical densities, experimental and empirical molar volume values, electrical activation energies, mass- and molar-magnetic susceptibilities as well as the total mass attenuation coefficients of all glasses were calculated. The gradual increase in halogen ions act to decrease experimental density from 2.45 to 2.13 g/cm3, while it acts to increase the molar volume. It was found that, the activation energy decreased around 0.3 eV as the halogen content was increased, it decreased also ongoing from chlorine to iodine that can be ascribed to the differences in ionic radii of halogen ions, and this was confirmed by the molar volume. It was supposed that the increase in the paramagnetic character of the studied glasses with the increase of halogen content may be due to the formation of VXO3 groups. Also, the magnetic properties were found to increase as the ionic radius of the introduced halogen ions increased, and this can be attributed to the increase in the internal vacancies through the network. Correlations were established between both the activation energy and molar susceptibility with molar volume. According to the results of the mass attenuation coefficients, it was found that, the sample contains 25 mol% NaI is the best one that can be used as -ray attenuator, but only at gamma-ray energies up to 356 keV.

Electrical and Structural properties of (ZnTiO3)/Epoxy System Nanocomposite Thin films

Spin coating technique using to prepare two layers of epoxy reinforced by weight (0Wt%,1Wt%,2Wt%,3Wt%,4Wt%) nano ZnTiO3additives uniform thin films with a fixed thickness of (0.7 ☐m) on glass floors at room temperature, dispersion and magnetic stirring techniques are used to prepare the nanocomposites thin films. The purpose of this study was to produce a new modified polymer (ZnTiO3/Epoxy) nanocomposite thin films then evaluate electrical and structural properties of these thin films. The electrical properties of thin films have a degree effect temperature on the resistance (R) of thin films within the range (303- 433) k or (30-160) C0. Electrical conductivity and activation energy of the thin film was calculated where the results indicate that there is a two activation energy and this means there is two mechanisms connection. It is also shown by measurements of the effect of the whole (ZnTiO3/Epoxy) nanocomposite thin films have a connection from the negative type (n-type). Stractural properties include XR-D and SEM. XRD, show crystal structure of zinc titanite (ZnTiO3) nano powder. Scanning electron microscopy SEM, show clearly analysis for different weight ratio affected thin films surfaces.

Engineering of physical properties of spray-deposited nanocrystalline Sb2O3 thin films by phase transformation

Nanostructured Sb2O3 thin films have been deposited onto glass substrates by using the chemical spray pyrolysis technique, and the effect of precursor solution volume on the physical properties was investigated for the first time. The prepared films were characterized in detail by using x-ray diffraction, field-emission scanning electron microscopy with energy dispersive x-ray analysis (FESEM-EDAX), UV-vis absorption and transmission spectroscopy, Raman spectroscopy analysis and electrical resistivity measurement. X-ray diffraction analysis shows that the senarmontite cubic phase is completely transferred to the valentinite orthorhombic phase as the precursor solution volume is increased. This phase transformation as a function of precursor volume is discussed in detail. The FESEM-EDAX analysis reconfirms the phase change showing well-defined nano-dimensional cubic hexagonal and orthorhombic octahedral morphologies with excellent stoichiometry. The optical property studies show that the bandgap energy of Sb2O3 varies from 3.43–3.98 eV as a function of precursor quantity. The as-grown Sb2O3 thin films are semiconducting in nature. The measured values of electrical resistivity and activation energy are found to be dependent on the spray solution volume. The electrical resistivity of deposited Sb2O3 thin films shows variation from 26.15 × 102–34.27 × 102 Ω cm and the activation energy of the films is in the order of 0.763–0.773 eV.

Electro-sonical deposition of nanostructured Sb2Se3 films for optoelectronic applications

In this study, a film of antimony selenide (Sb2Se3) was deposited on the Fluorine-doped tin oxide (FTO) as a substrate via electrodeposition at the potential of −0.55 V and the temperature of 25 °C. The effect of ultrasound waves during electrodeposition was also investigated at different times. The structural, morphological, optical, optoelectronic, and temperature dependence of the electrical resistance of the samples was investigated. The results showed formation of the polycrystalline phase of orthorhombic Sb2Se3. It was observed that when the ultrasound waves were used, the crystallite size (grain) and energy band gap decreased. It was found that in samples with a specified configuration, the intensity of the photocurrent decreased with increasing deposition time. Additionally, the anodic and cathodic photocurrent behaviors of the samples depended on the type and location of the electrode connection. Furthermore, the electrical resistance of the samples decreased with increasing temperature. In the sample with the lowest deposition time, conductivity and electrical activation energy were reduced by applying ultrasound waves, but they were increased by increasing the deposition time.

Study of the reaction of 1,4-benzoquinone with aniline oligomers and benzidine

Polymers and oligomers containing fragments of aniline oligomers and benzidine connected with p-benzoquinone have been synthesized. The UV, NMR and IR spectral data, as well as termal stubilities, of obtained compounds were studied. Some of obtained compounds were oxidized by K2S2O8 using different molar ratio. Electrical conductivities and conductivity activation energies of iodine and hydrochloric acid doped polymers were determined.

Structural, Magnetic and DC Electrical Resistivity Studies of Ni–Zn–Cr Ferrites Prepared by the Citrate-Gel Auto-Combustion Method

Nanocrystalline chromium substituted Ni–Zn nanoferrites with composition Ni0.5Zn0.5CrxFe2−xO4 (0 ≤ x ≤ 0.25, in steps of 0.05) have been synthesized using citrate-gel auto-combustion method. The as synthesized powder of the starting composition has been characterized by using TG–DTA in air atmosphere for the temperature up to 800 °C and X-ray diffraction for its structure. Upon confirming the spinel phase for the starting composition, the chromium substituted Ni–Zn ferrite nano powders were synthesized by the similar procedure. The as synthesized powders were pressed into pellets and toroids under uniaxial pressure followed with sintering in air atmosphere for 4 h at 1100 °C for electrical and magnetic characterizations. The X-ray diffraction studies revealed a decrease of the lattice constant and considerable modification in the structure of Ni–Zn ferrite with the substitution of Cr3+ for Fe3+ ions. The room temperature FT-IR spectra displayed three significant IR absorption bands in the wave number range of 350–600 cm−1 which is a characteristic of the spinel structure. The band positions and intensities were found to vary with chromium substitution in Ni–Zn ferrite. The room temperature DC electrical resistivity and activation energy for conduction in the Ni–Zn–Cr ferrite samples were measured by using the two-probe method while the AC resistivity studies were carried out in the frequency range of 1 kHz to 13 MHz and the all the observations have been discussed in the light of existing understanding.

Influence of annealing temperature and electrical conductivity of α-Fe2O3 nanoparticles for Schottky barrier diode

The microwave irradiation route is adopted for synthesizing hematite nanoparticles. The occurrence of different stages in iron oxide nanoparticles due to annealing temperature is validated from its phase transition. The temperature variation for annealing process is made subsequently in this experiment in steps of 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C and 900 °C. The formation and deformation of α-Fe2O3 (hematite) phase is identified from this work. The morphology, crystallinity and consistency in particles size are estimated from XRD, SEM and TEM image. The decrease in particle size is due to phase transformation which is identified from 78 to 24 nm. The specified involvement of thermal stability is tested from TGA analysis which is confirmed from phase transition in the XRD. Change in bandgap energy and respective blue shift for less particle sizes are elucidated from UV-DRS and PL spectra. The elemental presence Fe 2p and O 1s spectra indicates the valence states of Fe3+ and O2− from XPS and the VSM results are confirmed according to the increase in saturation and decrease in coercivity tended towards soft magnetic behaviour due to phase transition. The DC electrical conductivity and activation energy are calculated from I–V studies. The Schottky barrier diode parameters of ideality factor (n), barrier height (Φb) and reverse saturation current (I0) is calculated for both dark and light conditions.

Developing the magnetic, dielectric and anticandidal characteristics of SrFe12O19/(Mg0.5Cd0.5Dy0.03Fe1.97O4)x hard/soft ferrite nanocomposites

Hard/soft ferrite nanocomposites (NCs) (SrHF)/xMCD (1.0 ≤ x ≤ 3.0) consisting of SrFe12O19 HF (SrHF) and Mg0.5Cd0.5Dy0.03Fe1.97O4 (MCD) were obtained via one-pot sol-gel auto-combustion approach. The measurements of impedance spectroscopy are presented for new fractional (SrHF)/xMCD (1.0 ≤ x ≤ 3.0) hard/soft ferrite NCs, including reference soft and hard ferrites. The electrical conductivity and activation energies of fractional composite ferrites are observed to be regulated depending on the fractional ratios. It has been established that the temperature dependence of the DC conductivity obeys the Arrhenius law, especially for the fractional composite ferrites. To control the conduction mechanism, the conductivity and its frequency power exponent are evaluated based on a small polaron tunnelling model. Magnetic properties were verified by applying a DC magnetic field up to ±70 kOe at 300 and 10 K. Magnetization data significantly decreased with increasing fraction of MCD in NCs. These results showed that exchange-coupling was not achieved in these NCs by one-pot approach. Additionally, anticandidal activity of the synthesized nanomaterials was studied by evaluating the colony forming unit (CFU). The obtained results are significant for potential applications in the field of biomedicine.

Effect of Iodine Addition on Improving the Electrical Conductivity and Activation Energy of Electrospun PMMA Thin Films

Conductive polymer films were prepared from poly (methyl methacrylate) PMMA with (0, 0.3, 0.5, 0.7, and 0.9) wt. % of iodine, using electrospinning technique. A decrease was noticed in the polymer solution viscosity with increasing the iodine weight percentage while both surface tension and electrical conductivity of the polymer solutions were increased .The structure and morphology of the prepared films were characterized by scanning electron microscopy SEM, the average fiber diameter measured statistically from the SEM images and was equal to 800 nm for PMMA with 0.7 wt. % iodine thin film, and 400 nm for the pure PMMA thin film. The electrical conductivity was enhanced for the electrospun films with increasing iodine concentration, from (29.5518× 10-9 S/cm) for pure PMMA film to (59.3725× 10-9 S/cm) for PMMA with 0.9 wt. % of iodine additives at room temperature. Activation energy decreased from 0.4483 e.V for pure PMMA to 0.43029 e.V for PMMA with 0.9 wt. % iodine.

"Effect of Doping on Electrical Properties of Nickel Oxide (NPs) Prepared by Pulse Nd-Yag Laser Deposition Method "

"In this study, nickel oxide (NPs) films were produced by doping each element with 2% zinc, tin, iron, cobalt and magnesium. pulsed laser deposition was used to deposit them on glass substrates , and we used a pulsed Nd-YAG laser with a wavelength of 1064nm. All the films were annealed with one temperature (573k). The electrical properties of the prepared films were studied, such as the continuous electrical conductivity and activation energy, and we found that increasing the temperature increases the electrical conductivity values Also, the value of the electrical conductivity and the activation energy change according to the type of added doping. We also discovered many activation energy values in the temperature ranges of (308K-428K) , and observed the conduct of nanoparticle oxide doping with various metals at these temperatures.

Electrical conductivity and breakdown properties of some erbium oxide doped phosphovanadate glasses

Electrical conductivity and breakdown properties have been investigated for 70%V2O5·(30–x)%P2O5·x%Er2O3 glasses with (0 ≤ x ≤ 0.9). The conductivity measurements are carried out at frequency range from 80 to 3 × 106 Hz, and at temperature range from 303 to 463. The dc electrical conductivity (σdc) and dc activation energy (Edc) are shown to be relatively sensitive to the composition. σdc is found to vary between 3 × 10−4 and 0.024 Ω−1 m−1, and Edc is estimated to be in the range 0.36–0.44 eV. On the other hand, σac is found to vary between 7 × 10−4 and 0.15 Ω−1 m−1. Both σdc and σac are discussed according to the multi phonon hopping process of weak electron-lattice coupling, they are found to be proportional to Tpwith the exponent p between 11.5 and 13.15. All the samples exhibit a threshold type switching with a maximum current of about 3 mA. All the samples are found to present breakdown properties at different critical voltages. The threshold voltage (Vth) values are affected by ambient temperature, sample thickness and composition ratio. Measured surface temperature during the switching cycles and the calculated core temperature confirm the repeatedly switching of the samples without any internal thermal destruction occur.

Enhanced Photovoltaic and Photocatalytic Activity of Flower-Like Fe2WO6/WO3Contact Layers

Tungsten oxide hydrate (WO3·H2O) nanoparticle and Iron tungstate/tungsten oxide (Fe2WO6/WO3) nanocomposite have been synthesized via a facile hydrothermal route. Structural, optical, morphological and electrical properties of the synthesized samples were characterized by X-ray powder diffraction (XRD), UV-Visible spectroscopy, Field effect scanning electron microscopy (FE-SEM) with Energy-dispersive X-ray spectroscopy (EDX) and DC electrical conductivity measurement respectively. The powder X-ray diffraction (XRD) results confirm the formation of Fe2WO6/WO3 nanocomposite. Variation in the electrical conductivity and activation energy was studied by DC electrical conductivity studies. Fe2WO6/WO3 nanocomposites show a significant enhancement in the degradation of methyl blue than WO3·H2O nanoplates. The significant enhancement was due to flower-like morphology and the narrowing of the optical band gap which reduces the electron-hole pair recombination rate. The dye-sensitized solar cell (DSSC) was fabricated using WO3·H2O and Fe2WO6/WO3 films as photoanodes and it was observed that Fe2WO6/WO3 photoanode shows highest power conversion efficiency (PCE) i.e., 4.69% which can be achieved through high dye absorbing capacity.

Structural, morphological and electrical properties of Sm-Gd Co-doped ceria thin films for micro-solid oxide fuel cells

Thin film electrolytes of Sm and Gd doubly co-doped ceria, namely, Ce0.8Sm0.1Gd0.1O1.90 (CSGO) deposited by pulsed laser deposition (PLD) technique have been investigated. The influence of oxygen partial pressure (pO2) on structural and morphological properties of CSGO thin films deposited on Si (111) substrate was studied by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM) techniques. The XRD and FESEM results showed that the films were polycrystalline cubic structure with (111) oriented columnar structure. The co-doping strategy has strongly helped to stabilize the Ce4+ state as the lattice parameter of the films did not show any significant change under the influence of pO2 in the range of 2 × 10-4-3 × 10-2 mbar. The electrical conductivity and activation energy of CSGO thin film supported on NiO-GDC10 anode were found to be 0.48 mS.cm−1 and 0.5 eV respectively. Determination of significantly lower Ce3+ concentration (27%) in CSGO film by X-ray photon electron spectroscopy (XPS) suggests that Sm-Gd co-doping has strongly suppressed the conversion of Ce4+ to Ce3+ in the overall composition.