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    - CHEMICAL ENGINEERING (161 journals)
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    - ENGINEERING (1135 journals)
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ENGINEERING (1135 journals)            First | 2 3 4 5 6 7 8 9 | Last

International Journal of Intelligent Systems and Applications in Engineering     Open Access   (Followers: 1)
International Journal of Lifecycle Performance Engineering     Hybrid Journal  
International Journal of Machine Tools and Manufacture     Hybrid Journal   (Followers: 4)
International Journal of Manufacturing Research     Hybrid Journal   (Followers: 5)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (Followers: 7)
International Journal of Materials and Product Technology     Hybrid Journal   (Followers: 4)
International Journal of Mathematical Education in Science and Technology     Hybrid Journal   (Followers: 7)
International Journal of Mathematics in Operational Research     Hybrid Journal   (Followers: 1)
International Journal of Medical Engineering and Informatics     Hybrid Journal   (Followers: 5)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 4)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 1)
International Journal of Microwave Science and Technology     Open Access   (Followers: 2)
International Journal of Mobile Network Design and Innovation     Hybrid Journal   (Followers: 3)
International Journal of Multiphase Flow     Hybrid Journal   (Followers: 2)
International Journal of Nanomanufacturing     Hybrid Journal   (Followers: 1)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Nanotechnology     Hybrid Journal   (Followers: 5)
International Journal of Nanotechnology and Molecular Computation     Full-text available via subscription   (Followers: 3)
International Journal of Navigation and Observation     Open Access   (Followers: 6)
International Journal of Network Management     Hybrid Journal  
International Journal of Nonlinear Sciences and Numerical Simulation     Full-text available via subscription  
International Journal of Numerical Methods for Heat & Fluid Flow     Hybrid Journal   (Followers: 7)
International Journal of Optics     Open Access   (Followers: 1)
International Journal of Organisational Design and Engineering     Hybrid Journal   (Followers: 9)
International Journal of Pattern Recognition and Artificial Intelligence     Hybrid Journal   (Followers: 6)
International Journal of Pavement Engineering     Hybrid Journal   (Followers: 2)
International Journal of Physical Modelling in Geotechnics     Hybrid Journal   (Followers: 3)
International Journal of Plasticity     Hybrid Journal   (Followers: 6)
International Journal of Plastics Technology     Hybrid Journal  
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 4)
International Journal of Polymer Science     Open Access   (Followers: 16)
International Journal of Precision Engineering and Manufacturing     Hybrid Journal   (Followers: 5)
International Journal of Precision Technology     Hybrid Journal  
International Journal of Pressure Vessels and Piping     Hybrid Journal   (Followers: 3)
International Journal of Production Economics     Hybrid Journal   (Followers: 13)
International Journal of Quality and Innovation     Hybrid Journal   (Followers: 4)
International Journal of Quality Assurance in Engineering and Technology Education     Full-text available via subscription   (Followers: 2)
International Journal of Quality Engineering and Technology     Hybrid Journal   (Followers: 2)
International Journal of Quantum Information     Hybrid Journal  
International Journal of Rapid Manufacturing     Hybrid Journal   (Followers: 1)
International Journal of Reliability, Quality and Safety Engineering     Hybrid Journal   (Followers: 6)
International Journal of Renewable Energy Technology     Hybrid Journal   (Followers: 8)
International Journal of Robust and Nonlinear Control     Hybrid Journal   (Followers: 2)
International Journal of Science Engineering and Advance Technology     Open Access  
International Journal of Sediment Research     Full-text available via subscription   (Followers: 1)
International Journal of Self-Propagating High-Temperature Synthesis     Hybrid Journal   (Followers: 2)
International Journal of Signal and Imaging Systems Engineering     Hybrid Journal  
International Journal of Six Sigma and Competitive Advantage     Hybrid Journal  
International Journal of Social Robotics     Hybrid Journal   (Followers: 1)
International Journal of Software Engineering and Knowledge Engineering     Hybrid Journal   (Followers: 1)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 2)
International Journal of Speech Technology     Hybrid Journal   (Followers: 3)
International Journal of Spray and Combustion Dynamics     Full-text available via subscription   (Followers: 6)
International Journal of Surface Engineering and Interdisciplinary Materials Science     Full-text available via subscription   (Followers: 1)
International Journal of Surface Science and Engineering     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Engineering     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Manufacturing     Hybrid Journal   (Followers: 4)
International Journal of Systems and Service-Oriented Engineering     Full-text available via subscription  
International Journal of Systems Assurance Engineering and Management     Hybrid Journal  
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 2)
International Journal of Technoethics     Full-text available via subscription  
International Journal of Technology Management and Sustainable Development     Hybrid Journal   (Followers: 1)
International Journal of Technology Policy and Law     Hybrid Journal   (Followers: 4)
International Journal of Telemedicine and Applications     Open Access   (Followers: 2)
International Journal of Thermal Sciences     Hybrid Journal   (Followers: 5)
International Journal of Thermodynamics     Open Access   (Followers: 2)
International Journal of Turbo & Jet-Engines     Full-text available via subscription  
International Journal of Ultra Wideband Communications and Systems     Hybrid Journal  
International Journal of Vehicle Autonomous Systems     Hybrid Journal   (Followers: 1)
International Journal of Vehicle Design     Hybrid Journal   (Followers: 6)
International Journal of Vehicle Information and Communication Systems     Hybrid Journal   (Followers: 2)
International Journal of Vehicle Noise and Vibration     Hybrid Journal   (Followers: 3)
International Journal of Vehicle Safety     Hybrid Journal   (Followers: 5)
International Journal of Vehicular Technology     Open Access   (Followers: 2)
International Journal of Virtual Technology and Multimedia     Hybrid Journal   (Followers: 4)
International Journal of Wavelets, Multiresolution and Information Processing     Hybrid Journal  
International Journal on Artificial Intelligence Tools     Hybrid Journal   (Followers: 4)
International Nano Letters     Open Access   (Followers: 9)
International Review of Applied Sciences and Engineering     Full-text available via subscription  
Inverse Problems in Science and Engineering     Hybrid Journal   (Followers: 2)
Ionics     Hybrid Journal  
IPTEK The Journal for Technology and Science     Open Access  
IRBM News     Full-text available via subscription  
Irrigation and Drainage Systems     Hybrid Journal  
ISA Transactions     Full-text available via subscription   (Followers: 1)
ISRN - International Scholarly Research Notices     Open Access   (Followers: 69)
ISRN Nanotechnology     Open Access  
ISRN Signal Processing     Open Access  
ISRN Thermodynamics     Open Access  
IT Professional     Full-text available via subscription   (Followers: 3)
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 2)
Journal of Advanced Manufacturing Systems     Hybrid Journal   (Followers: 6)
Journal of Aerosol Science     Hybrid Journal   (Followers: 1)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 166)
Journal of Alloys and Compounds     Hybrid Journal   (Followers: 8)
Journal of Analytical and Applied Pyrolysis     Hybrid Journal   (Followers: 3)
Journal of Analytical Science & Technology     Open Access   (Followers: 4)
Journal of Analytical Sciences, Methods and Instrumentation     Open Access   (Followers: 1)
Journal of Applied Analysis     Full-text available via subscription  
Journal of Applied and Industrial Sciences     Open Access  

  First | 2 3 4 5 6 7 8 9 | Last

Journal Cover Ionics
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1862-0760 - ISSN (Online) 0947-7047
     Published by Springer-Verlag Homepage  [2210 journals]   [SJR: 0.522]   [H-I: 25]
  • Investigation of the structural properties of poly(ethylene oxide)
           copolymer as gel polymer electrolyte and durability test in dye-sensitized
           solar cells
    • Abstract: Abstract We investigated the structural and thermal properties of a gel polymer electrolyte prepared with poly(ethylene oxide-co-2-(2-methoxyethoxy)ethyl glycidyl ether) (P(EO/EM) matrix, γ-butyrolactone (GBL), and LiI/I2. Nuclear magnetic resonance spectroscopy measurements were carried out in different temperatures for the aforementioned electrolyte composition in order to understand the interaction between the components of the gel. Within the studied temperature range, the overall Li ion mobility depends on the contribution of the Li ion mobility in GBL molecules and in the polymer matrix. Small angle X-ray scattering (SAXS) measurements of the gel electrolyte indicated an order periodicity of 7–8 nm, which provides evidence for an effective miscibility of GBL and P(EO/EM), since no structural changes were observed by SAXS data (the systems are stable within the studied temperature range). Indeed, this result corroborates Nuclear Magnetic Resonance Spectroscopy (NMR) data, since at room temperature, it is not possible to distinguish magnetic interactions between P(EO-EM) and GBL molecules, indicating the existence of a single phase. Thermogravimetric analysis shows that the gel electrolyte meets thermal stability requirements for application in photoelectrochemical devices. The performance of dye-sensitized solar cells (DSSC) based on this polymer electrolyte with different GBL concentrations was monitored for 30 days. Device with electrolyte containing 30 wt.% of GBL gave the most promising durability results in this study; the performance of this device decreased by less than 10 % in the course of 30 days.
      PubDate: 2014-12-14
  • SO 2 gas sensor based on Ag-Ag 2 SO 4 -BaSO 4 sensing electrode
    • Abstract: Abstract A sulfur dioxide (SO2) gas sensor based on a novel structural sensing electrode was fabricated. The sensor consists of yttria-stabilized zirconia as the oxygen ion conductor, silver sulfate-based salts as the auxiliary phase, a silver/platinum mixed paste as the sensing electrode/catalyst, and a platinum paste as the reference electrode. Ball milling was employed to decrease the particle size of the silver sulfate-barium sulfate (Ag2SO4-BaSO4) auxiliary phase. After the Ag2SO4-BaSO4 mixture ball-milling for 20 h, the as-obtained sensor showed the highest sensitivity to SO2 gas. Furthermore, in order to optimize the sensing electrode, particles of metallic silver were mixed with silver sulfate-based salts, and the as-designed sensing electrode displayed an improved sensitivity to SO2 gas at a low temperature (400 °C).
      PubDate: 2014-12-14
  • Relaxation behavior in clay-reinforced polymer nanocomposites
    • Abstract: Abstract The effect of clay reinforcement on dielectric, conductivity, and mechanical relaxation behavior of a polymer clay nanocomposite film is reported. Polymer nanocomposite is composed of three component polymers (polyacrylonitrile) as a host matrix, salt (LiPF6) as conducting species, and clay (sodium montmorillonite) as intercalant. The macroscopic parameters like polymer glass transition temperature and available free mobile charge carriers have been analyzed properly using dynamic mechanical analysis and dielectric analysis. Dielectric analysis indicated distribution of relaxation time as a function of clay concentration, whereas conductivity spectrum exhibited dispersion at lower frequency followed by saturation region at intermediate frequency. The dispersion behavior is related to the electrode polarization attributed to faster ion dynamics. The dielectric and conductivity relaxation are in excellent correlation with mechanical relaxation owing to the changes in glass transition temperature due to polymer-ion-clay interaction. The proposed mechanism is a sequel to the experimental results.
      PubDate: 2014-12-11
  • Synthesis of Li 3 V 2 (PO 4 ) 3 /C with enhanced rate performance by a
           two-step technique
    • Abstract: Abstract The nano-particles, Li3V2(PO4)3 embedded in carbon matrix, are synthesized by a novel two-step procedure based on a sol–gel method. In the two-step process, the carbon-encapsulated trivalent vanadium phosphorus precursors are obtained without adding lithium compound in the first step. Because of carbon matrix, small particle size of Li3V2(PO4)3/C composite is obtained in the second step, which involves lithiation and heating to 800 °C in argon. The electronic conductivity of Li3V2(PO4)3/C composite is 2.88 × 10−3 S cm−1, increased by five orders of magnitude compared with the pristine Li3V2(PO4)3 (2.3 × 10−8 S cm−1). The prepared Li3V2(PO4)3/C shows high discharge capacity 132 mAh g−1 (3.0–4.3 V), which is up to 99.2 % of the theoretical value, and good high-rate specific discharge capacity, which is greater than 100 mAh g−1 at a rate of 10 C. Even after cycling at 15 C, the charge–discharge performance of the prepared Li3V2(PO4)3/C cathode hardly deteriorates at 1 C indicating that the structure of Li3V2(PO4)3 is not destroyed irreversibly at high rate. The improved electrochemical properties of the Li3V2(PO4)3/C cathode electrodes are also verified by electrochemical impedance spectroscopy.
      PubDate: 2014-12-11
  • The effect of phenol–formaldehyde resin on the electrochemical
           properties of carbon-coated LiFePO 4 materials in pilot scale
    • Abstract: Abstract Carbon sources have large impacts on the capacity of LiFePO4/C mixture. In this work, mixed carbon sources with different ratios were employed to prepare promising carbons to improve the capacity of LiFePO4-based cathode. The highest electrical performance was achieved with sample prepared from carbon source mixed of 30 % PF and 70 % sucrose. The discharge capacity of this novel cathode, whose actual content was 1.81 wt.%, was 162 mAhg−1 at a 0.1C rate or 150 mAhg−1 at 1C rate. Moreover, SEM, TEM, and Raman spectroscopy investigations were performed to explore the enhanced mechanism of this modified LiFePO4-based cathode. The results suggest that the enhanced electrochemical performance can be ascribed to the high ratio of sp2/sp3, which virtually ameliorated the electrical conductivity and electron transfer.
      PubDate: 2014-12-06
  • CN x -modified montmorillonite as support to immobilize Pd and its
           enhanced electrocatalytic activity for formic acid oxidation
    • Abstract: Abstract Nature clay, i.e., montmorillonite (MMT), can be used as support materials of anode electrocatalyst in the direct formic acid fuel cell. The nitrogen-containing composite support (MMT-CN x ) was prepared via carbonizing MMT which was covered by polyaniline. Pd/MMT-CN x and Pd/C catalysts were prepared as formic acid oxidation catalysts using an improved liquid reduction method. The composite, structure, surface properties, and electrical conductivity of the supports and catalysts were studied by energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical impedance spectroscopy (EIS). The results showed that well-dispersed Pd nanoparticles with a narrow size distribution of 3.5–5.5 nm could be easily prepared on the MMT-CN x . Larger electrochemical specific area (ECSA) was obtained for Pd/MMT-CN x than Pd/C according to CO-stripping voltammetry. Cyclic voltammetry (CV) and chronoamperometry (CA) measurements showed better catalytic activity and stability of the Pd/MMT-CN x catalyst than the conventional Pd/C catalyst for formic acid electrooxidation. Larger ECSA and doped nitrogen in the support of the Pd/MMT-CN x catalyst may be the main reason of higher activity and better stability for formic acid oxidation compared with the Pd/C catalyst. The results offered potential application of composite support (MMT-CN x ) for the catalyst of the direct formic acid fuel cell.
      PubDate: 2014-12-06
  • Effect of Ti-doping on the electrochemical performance of lithium
           vanadium(III) phosphate
    • Abstract: Abstract Carbon-coated and titanium-substituted lithium vanadium phosphate composites have been successfully prepared through a sol-gel method followed by solid-state reaction under argon. Li3V1.9Ti0.1(PO4)3-C (LVT10PC) and Li3V1.85Ti0.15(PO4)3-C (LVT15PC) were investigated using X-ray powder diffraction, thermal analysis, transmission electron microscopy, cyclic voltammetry, and galvanostatic tests. Different models for the solid solution mechanism in this system are discussed. Electrochemical tests, at a charge-discharge rate of 0.2 C, in the range 2.8–4.4 V show that LVT10PC delivers the highest discharge capacity of 121 mA h g−1 and declines to 115.7 mA h g−1 up to the 60th cycle, corresponding to a 4.4 % loss. At low levels, titanium substitution is found to increase initial discharge capacity compared to the carbon-coated unsubstituted system (LVPC). Further substitution is found to have detrimental effects on initial discharge capacity and cycling behaviour.
      PubDate: 2014-12-05
  • PtSn nanoparticles supported on iron nanoparticles wrapped inside
           nitrogen-doped carbon for ethanol oxidation
    • Abstract: Abstract Iron nanoparticles wrapped in N-doped carbon (INC) were synthesized by a two-step method which includes a hydrothermal and a thermal treatment. The PtSn nanoparticles were then deposited on the resulting carbon material using an ethylene glycol reduction method. Scanning electron microscopy images indicated INC had an interconnected, porous framework with continuous macropores in the micrometer range. Transmission electronic microscopy and X-ray diffraction results proved that the iron nanoparticles were completely wrapped in the N-doped carbon. Cyclic voltammograms for ethanol oxidation showed that the mass activity on PtSn/INC electrode reaches 424.5 mA mg−1 Pt, 1.64 times as large as that for PtSn/C (259.0 mA mg−1 Pt). PtSn/INC also exhibited better durability in ethanol oxidation reaction than PtSn/C. These results indicated that INC is a potential high-performance catalyst support material for fuel cell catalysts.
      PubDate: 2014-12-03
  • Structural and electrochemical properties of LiFe
           1 − 3x/2 Bi x PO 4 /C synthesized by sol–gel
    • Abstract: Abstract In this study, LiFe1 − 3x/2Bi x PO4/C cathode material was synthesized by sol–gel method. From XRD patterns, it was found that the Bi-doped LiFePO4/C cathode material had the same olivine structure with LiFePO4/C. SEM studies revealed that Bi doping can effectively decrease the particle sizes. It shortened Li+ diffusion distance between LiFePO4 phase and FePO4 phase. The LiFe0.94Bi0.04PO4/C powder exhibited a specific initial discharge capacity of about 149.6 mAh g−1 at 0.1 rate as compared to 123.5 mAh g−1 of LiFePO4/C. EIS results indicated that the charge-transfer resistance of LiFePO4/C decreased greatly after Bi doping.
      PubDate: 2014-12-01
  • Ball-milled Ni-Mn-Zn hydroxide for alkaline secondary battery
    • Abstract: Abstract In our previous study, Mn-substituted nickel hydroxide (Ni0.8Mn0.2(OH)2) was prepared by a simple ball milling method to reduce the cost of nickel hydroxide for alkaline secondary battery, but compared to the Ni(OH)2 electrode, the Ni0.8Mn0.2(OH)2 one showed an obvious decrease in its discharge potential. In this paper, Zn and Mn co-substituted nickel hydroxide (Ni0.8Mn0.2 − x Zn x (OH)2, x = 0–0.075) is prepared by ball milling. The results of the cyclic voltammetry (CV) tests illustrate that the co-reduction of Mn(IV) to Mn(III) and NiOOH is observed on the Ni0.8Mn0.2 − x Zn x (OH)2 electrodes, and it has a lower reduction potential than NiOOH. The co-substitution of Zn can effectively increase the co-reduction potential. The ball-milled Ni0.8Mn0.15Zn0.05(OH)2 electrode has a similar capacity (about 270 mAh g−1 at a 0.2C rate) and cycling durability to the commercial Ni(OH)2 with ball milling treatment, but the former has better high-power performance.
      PubDate: 2014-12-01
  • Electrochemical determination of ionization constants of
    • Abstract: Abstract Cyclic voltammetry of ferrocene at glassy carbon electrode in acetonitrile (ACN), ο-nitrophenyloctylether (NPOE) and ACN-NPOE mixture with 0.2 M tetrabutylammonium tetrafluoroborate (TBABF4) were investigated. Both cathodic and anodic peak current were diffusion-controlled at any NPOE fraction. However, the peak current was decreased with the increasing NPOE fraction. In addition, the peak potential difference increased not only with an increase in the NPOE fraction but also in the scan rate, while the values of half-wave potential did not vary largely with the fraction or the scan rate. This indicated that the variation of peak current and peak potential should be due to the variation of the solution resistance. In order to demonstrate this assumption, the conductance of TBABF4 in ACN, NPOE, and ACN-NPOE mixture were determined by AC impedance. All of the solution conductances were inversely linear to the viscosity of the solvent, which was increased with the fraction of NPOE. The calculated ionization constant of TBABF4 in ACN was 2.8 times of that in NPOE. TBABF4 in ACN can work as a supporting electrolyte, whereas they work partly in NPOE.
      PubDate: 2014-12-01
  • The influence of sodium gluconate on nickel and manganese codeposition
           from acidic chloride-sulfate baths
    • Abstract: Abstract Nickel and manganese were codeposited from acidic chloride-sulfate solution in the presence and without sodium gluconate as complexing and buffering agent. Equilibrium pH-dependent distribution of soluble species in the baths was calculated. Deposition of metals was studied by cyclic voltammetry and Hull cell tests. Deposits were obtained in potentiostatic (−1.6 to −1.7 V vs. Ag/AgCl) and galvanostatic (4–8 A/dm2) conditions. It was found that the buffering action of gluconate ions improved the quality of the deposits, and compact Ni-Mn with a grid of fine crack layers was produced. The additive inhibited the formation of nonmetallic inclusions represented by decreased oxygen content in the deposits. Layers produced at constant potentials contained 67–79 % Ni, 1–8 % Mn, and 15–30 % O. Under galvanostatic conditions, the average compositions were in the range of 18–80 % Ni, 2–48 % Mn, and 17–42 % O. Despite of the bath composition, the main cathodic reaction was hydrogen evolution resulting in very low amounts of the cathodic deposits.
      PubDate: 2014-12-01
  • Effect of molybdenum doping on the electrochromic properties of tungsten
           oxide thin films by RF magnetron sputtering
    • Abstract: Abstract Thin films of pure and molybdenum (Mo)-doped tungsten trioxide (WO3) were deposited on indium tin oxide (ITO)-coated glass and Corning glass substrates by RF magnetron sputtering technique. The effect of Mo doping on the structural, morphological, optical and electrochromic properties of WO3 films was studied systematically. The energy dispersive X-ray analysis (EDAX) revealed that the films consist of molybdenum concentrations from 0 to 2 at.%. X-ray diffraction (XRD) studies indicated that with the increase of Mo concentration the structural phase transformation takes place from polycrystalline to amorphous phase. The crystallite size of the films decreased from 24 to 12 nm with increase of doping concentration of Mo in WO3. Scanning electron microscope (SEM) analysis revealed that Mo dopant led to significant changes in the surface morphology of the films. The electrochemical and electrochromic performance of the pure and Mo-doped WO3 were studied. The WO3 films formed with 1.3 at.% Mo dopant concentration exhibited high optical modulation of 44.3 % and coloration efficiency of 42.5 cm2/C.
      PubDate: 2014-12-01
  • Perborate as novel fuel for enhanced performance of membraneless fuel
    • Abstract: Abstract This paper presents the development of membraneless sodium perborate fuel cell using acid/alkaline electrolyte. In the acid/alkaline electrolyte, perborate works both as an oxidant as well as reductant. Sodium perborate affords hydrogen peroxide in aqueous medium. The cell converts the energy released by H2O2 decomposition with H+ and OH− ions into electricity and produces water and oxygen. Such a novel design eliminates the need of a membrane, in which acid and alkaline electrolytes contact with each other. At room temperature, the laminar flow-based microfluidic membraneless fuel cell can reach a maximum power density of 34 mW/cm2 with the molar ratio of [Perborate]/[NaOH] = 1 as fuel and [Perborate]/[H2SO4] = 2 as oxidant. The paper reports for the first time the use of sodium perborate as the oxidant and reductant. The developed fuel cell emits no CO2, features no proton exchange membrane, inexpensive catalysts, and simple planar structure, which enables high design flexibility and easy integration of the microscale fuel cell into actual microfluidic systems and portable power applications.
      PubDate: 2014-12-01
  • Synthesis and characteristics of KTa 0.5 Nb 0.5 O 3 thin films
    • Abstract: Abstract KTa0.5Nb0.5O3 thin films were synthesized via a metal-organic solution. Characteristics were measured, such as X-ray diffraction pattern, surface morphology and roughness, and electric properties. The synthesized films have a (100) preferential growth orientation on Si (100) substrate. The homogeneous microstructure and smooth surface benefit to the good electric properties of the thin films. The current density-voltage characteristic shows an unexpected feature of the transition from linear to nonlinear, which can be explained by the space-charge-limited mode. Dielectric constant and loss of the thin films decrease with the increase of frequency. The decrease of dielectric loss is related to the decrease of net polarization in material. The decrease of dielectric constant can be explained by Debye formula. The phase transition temperature T c is about 102 °C for KTa0.5Nb0.5O3 materials.
      PubDate: 2014-12-01
  • Conduction mechanism of lithium bis(oxalato)borate–cellulose acetate
           polymer gel electrolytes
    • Abstract: Abstract Polymer gel electrolytes (PGE) belonging to salt–solvent–polymer hybrid systems are prepared using a mixture of lithium bis(oxalato)borate (LiBOB), γ-butyrolactone (γ-BL), and cellulose acetate (CA). The increase in ionic conductivity of PGE is due to the dissociation of ion aggregates, as confirmed by Fourier transform infrared analysis. The highest conductivity attained by the PGE is 7.05 mS cm−1 at 2.4 wt.% CA. The plots of conductivity–temperature show a classical Arrhenius relationship. The electrical properties of the sample with the highest conductivity are analyzed using electrical permittivity and electric modulus formalism studies. Meanwhile, the frequency-dependent conductivity of the polymer gel electrolyte adheres to Jonscher’s power law. Conduction mechanism study also shows that the 2.4 wt.% CA PGE is in agreement with the small polaron hopping model.
      PubDate: 2014-12-01
  • Binary composite ionic liquids [bmim][BF 4 ] and [bmim][Ac] for
           electrochemical reduction of nitrobenzene
    • Abstract: Abstract The binary composite ionic liquid mixtures composed of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) and 1-butyl-3-methylimidazolium acetate ([bmim][Ac]) were studied and used in electroreduction of nitrobenzene for the first time. 1H NMR and Fourier transform infrared (FTIR) spectroscopy were carried out to acquire a deep understanding of the interaction of binary ionic liquids, and UV/Vis spectroscopy was used to study the interaction between the mixture of ionic liquids and nitrobenzene. It was found that chemical shifts of all protons were changed and significant changes in the anion IR bands were induced, and the UV maximum absorption wavelength and absorbance of nitrobenzene in binary ionic liquids were different from those in the neat ionic liquid. The electrochemical reduction behavior of nitrobenzene in binary composite ionic liquids on platinum electrode was studied by cyclic voltammetry, in situ Fourier transform infrared spectroscopy, and constant potential electrolysis. Results indicated that the reduction of nitrobenzene in binary composite ionic liquids demonstrated higher current densities with a more positive potential, and the product (azobenzene) showed higher yield and selectivity in the composite ionic liquids than in the neat ionic liquids; the concentrations of water in the binary mixtures of ionic liquids had great effect on the electrochemical behavior of nitrobenzene. In the end, the mechanism of reduction of nitrobenzene in binary mixtures of ionic liquids was discussed.
      PubDate: 2014-12-01
  • Electrochemical and structural study of neodymium nickelate thick film
           deposited by spin coating on an oxyapatite electrolyte
    • Abstract: Abstract The electrochemical characteristics of an Nd2NiO4 cathode, synthesized using the citric acid-nitrate combustion method and symmetrically deposited by spin coating on both surfaces of an La9.33Si5.3Al0.7O25.65 (LSAO) electrolyte, were studied using AC impedance spectroscopy. It was found that, varying the temperature (600 to 850 °C) and the oxygen partial pressure (0.2–10−7 atm), the impedance characteristics of the electrode could be determined by three different processes. Said processes were ionic conduction in the electrode bulk, interfacial charge transfer, and gas-phase diffusion, all of which are based on the temperature and oxygen partial pressure dependence on the polarization resistance, which is associated with each individual processes as well as on the corresponding capacitance values.
      PubDate: 2014-12-01
  • Preparation and characterization of polyaniline+TiO 2 composite films
    • Abstract: Abstract In this work, we have prepared electrochemically and studied a composite materials based on an organic conducting polymer, polyaniline (PANI), in which inorganic semiconductor titanium dioxide (TiO2) particles were incorporated with different concentrations. The polyaniline/titanium dioxide composite material which had been deposited by cyclic voltammetry on substrates of indium tin oxide was then characterized. The cyclic voltammogram showed one redox couple characteristic of the oxidation and reduction states of the produced composite material. The impedance spectroscopy study showed that the resistance of the film increases with the TiO2 cocntent incorporated in the polymer. The incorporation of TiO2 in PANI covering the surfaces was confirmed by the scanning electron microscopy and the energy dispersive X-ray analysis. The morphological analysis of the film surfaces showed that the TiO2 nanoparticle increased the roughness. These observations allow to consider a new approach to improve the physicochemical properties of the interface between the organic and inorganic material. The I–V characteristics of PANI+TiO2 heterostructure diode showed the nonlinear nature of the I–V curve of PANI+TiO2 heterostructure device.
      PubDate: 2014-12-01
  • Increasing the crystallite and conductivity of polypyrrole with dopant
    • Abstract: Abstract The chemical polymerization method is very convenient for obtaining a plurality of the polymer. Chemical synthesizes of polypyrrole (PPy) were performed in acetonitrile solutions containing different dopants: dodecylbenzene sulphonic acid (DBSA), tetrafluoroborate (BF4 −), perchlorate (ClO4 −) and oxalate (C2O4 2−). These polymers were characterized by using scanning electron microscopy (SEM), ultraviolet–visible (UV–Vis) spectrophotometer, Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) techniques and dry conducting measurement. It was observed that the interactions between the polymers and dopant materials are completely different from each other. As a result of this interaction, the conductivities and crystal structures of PPy are also different from each other. Results in this work showed that the dopants used affected both electrical conductivities and crystal structures of PPy.
      PubDate: 2014-12-01
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