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  Subjects -> ENGINEERING (Total: 1955 journals)
    - CHEMICAL ENGINEERING (153 journals)
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    - ELECTRICAL ENGINEERING (82 journals)
    - ENGINEERING (1111 journals)
    - ENGINEERING MECHANICS AND MATERIALS (290 journals)
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ENGINEERING (1111 journals)            First | 2 3 4 5 6 7 8 9 | Last

International Journal of Manufacturing Research     Hybrid Journal   (Followers: 6)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (Followers: 8)
International Journal of Materials and Product Technology     Hybrid Journal   (Followers: 4)
International Journal of Mathematical Education in Science and Technology     Hybrid Journal   (Followers: 6)
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: 3)
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 Navigation and Observation     Open Access   (Followers: 5)
International Journal of Network Management     Hybrid Journal  
International Journal of Nonlinear Sciences and Numerical Simulation     Full-text available via subscription   (Followers: 1)
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: 6)
International Journal of Precision Technology     Hybrid Journal  
International Journal of Pressure Vessels and Piping     Hybrid Journal   (Followers: 2)
International Journal of Production Economics     Hybrid Journal   (Followers: 10)
International Journal of Quality and Innovation     Hybrid Journal   (Followers: 3)
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: 2)
International Journal of Reliability, Quality and Safety Engineering     Hybrid Journal   (Followers: 4)
International Journal of Renewable Energy Technology     Hybrid Journal   (Followers: 7)
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 Assurance Engineering and Management     Hybrid Journal  
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 2)
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: 4)
International Journal of Thermodynamics     Open Access   (Followers: 1)
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: 4)
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: 6)
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: 2)
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 1)
Journal of Advanced Manufacturing Systems     Hybrid Journal   (Followers: 7)
Journal of Aerosol Science     Hybrid Journal   (Followers: 2)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 133)
Journal of Alloys and Compounds     Hybrid Journal   (Followers: 7)
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  
Journal of Applied Logic     Full-text available via subscription  
Journal of Applied Physics     Hybrid Journal   (Followers: 162)
Journal of Applied Probability     Full-text available via subscription   (Followers: 6)
Journal of Applied Research and Technology     Open Access  
Journal of Applied Science and Technology     Full-text available via subscription  
Journal of Applied Sciences     Open Access   (Followers: 5)
Journal of Architectural Engineering     Full-text available via subscription   (Followers: 6)

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Journal Cover Ionics
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1862-0760 - ISSN (Online) 0947-7047
     Published by Springer-Verlag Homepage  [2209 journals]   [SJR: 0.522]   [H-I: 25]
  • Application of an ionic liquid-functionalized Mg       class="a-plus-plus">2Al layered double hydroxide
           for the electrochemical myoglobin biosensor
    • Abstract: Abstract In this paper, an ionic liquid 1-carboxyl-methyl-3-methylimidazolium tetrafluoroborate (CMMIMBF4)-functionalized Mg2Al layered double hydroxide (LDH) was synthesized and further used for the immobilization of myoglobin (Mb) on the surface of a carbon ionic liquid electrode to get a new electrochemical biosensor. Ultraviolet–visible and Fourier transform–infrared spectroscopies confirmed that Mb in the CMMIMBF4-LDH remained its native secondary structure, which was attributed to the biocompatibility of the materials used. On the cyclic voltammograms, a pair of well-defined redox peaks appeared, indicating that direct electron transfer of Mb was realized in the modified electrode. The formal peak potential was calculated as −0.209 V (vs. SCE), which was the typical characteristics of the Mb heme Fe(III)/Fe(II) redox couples. The fabricated Mb sensor exhibited good electrocatalytic activity to the reduction of trichloroacetic acid in the range from 1.0 to 17.0 mmol L−1 with the detection limit as 0.344 mmol L−1 (3σ), and the apparent Michaelis–Menten constant was calculated as 13.5 mmol L−1. Thus, the ionic liquid-functionalized LDH exhibited the potential application in the electrochemical sensor for redox proteins.
      PubDate: 2014-10-01
       
  • Highly active Pd/WO       class="a-plus-plus">3-CNTs catalysts for formic
           acid electrooxidation and study of the kinetics
    • Abstract: Abstract The new Pd/WO3-CNTs catalysts are prepared for formic acid electrooxidation in direct formic acid fuel cells (DFAFCs). According to XRD, TEM, and HRTEM results, WO3 particles are covered or overlapped with Pd particles, which have a uniform and narrow size distribution due to the highly dispersion of WO3-CNTs. The electrochemical results show significantly enhanced electrocatalytic performances for formic acid oxidation on Pd/WO3-CNTs catalysts, especially its dramatically improved stability and excellent tolerance to CO poisoning, which is mainly ascribed to the interaction between Pd and WO3. Therefore, Pd/WO3-CNTs catalysts show the great potential as less expensive and more efficient electrocatalyst for DFAFCs. Additionally, the kinetic parameters such as the charge transfer parameter and the diffusion coefficient of formic acid electrooxidation on 20 %Pd/20 %WO3-CNTs were obtained. The new Pd/WO3-CNTs catalysts are prepared and studied in the oxidation of formic acid, and the significantly enhanced electrocatalytic performances, especially its dramatically improved stability and excellent tolerance to CO poisoning show great potential as less expensive and more efficient electrocatalyst for the direct formic acid fuel cells.
      PubDate: 2014-10-01
       
  • Enhanced electrochemical properties of Al-doped bulk manganese oxides
           synthesized by a facile liquid-phase method
    • Abstract: Abstract Aluminum doped MnO2 nanoparticles were synthesized by a simple liquid-phase process using potassium permanganate as oxidation agent, glycol as reducing agent. Specific capacitance of the optimal sample electrode can reach 290 F g−1 after 10 cycles. The electrode also exhibits excellent cycle stability, retaining 86.6 % after 1,000 cycles. The infrared absorption bands of aluminum doped manganese oxide shift to high wave number for the reason that aluminum ion has smaller nuclear charge. The doping of aluminum strengthens the Mn–O bond and decreases the aggregation degree, thus the electrochemical properties are enhanced.
      PubDate: 2014-10-01
       
  • Fabrication of functionalized nitrogen-doped graphene for supercapacitor
           electrodes
    • Abstract: Abstract A unique and convenient one-step hydrothermal process for synthesizing functionalized nitrogen-doped graphene (FGN) via ethylenediamine, hydroquinone, and graphene oxide (GO) is described. The graphene sheets of FGN provide a large surface area for hydroquinone molecules to be anchored on, which can greatly enhance the contribution of pseudocapacitance. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and electrochemical workstation are used to characterize the materials. The nitrogen content exhibited in FGN can be up to 9.83 at.%, and the as-produced graphene material shows an impressive specific capacitance of 364.6 F g−1 at a scan rate of 10 mV s−1, almost triple that of the graphene (GN)-based one (127.5 F g−1). Furthermore, the FGN electrodes show excellent electrochemical cycle stability with 94.4 % of its initial capacitance retained after 500 charge/discharge cycles at the current density of 3 A g−1.
      PubDate: 2014-10-01
       
  • Simple synthesis of iron       class="a-plus-plus">III sulfophenyl phosphate
           
    • Abstract: Abstract IronIII sulfophenyl phosphate (FeSPP) is successfully synthesized by an optimized process from the reaction of ironIII chloride and m-sulfophenyl phosphonic acid (msPPA) by a simple and environmentally friendly method. Experimental results show FeSPP has a kind of layered structure, and multilayer sheet is about 2 nm thick. FeSPP exhibits good thermal stability and does not decompose under 200 °C. Protons transfer through vehicle and Grotthuss mechanisms at different relative humidities (RH). The conductivity of FeSPP can reach to 0.115 S/cm at 180 °C and RH = 100 %. Under this condition, vehicle mechanism plays the leading role, and the Grotthuss mechanism plays the minor role. At low RH, Grotthuss plays the leading role, and vehicle plays the minor role. In a drying oven at 180 °C, the proton conductivity remains 2.15 × 10−3 S/cm. Good conductivities at different RH and thermal stabilities clearly demonstrate that FeSPP is a highly effective conductor. It can be used as catalysts, chemical sensors, and in the preparation of composite membrane.
      PubDate: 2014-10-01
       
  • Conductivity and dielectric relaxation of gelatin films with glycerol as
           plasticizer
    • Abstract: Abstract Gelatin films complexed with ionic salts are of current interest as potential solid polymer electrolytes. However, even without salt, gelatin films are found to have quite high ionic conductivity at room temperature (around 30 °C), when plasticized with an adequate fraction of glycerol. In the present work, the admittance and dielectric properties of gelatin are studied as a function of glycerol content and temperature. An enhancement in the ionic conductivity by four orders of magnitude to ∼9.13 × 10−3 S/m at room temperature is obtained by adding 35.71 wt% of glycerol. This enhancement appears to be correlated with the changes in the local microstructure on plasticizer addition. Admittance and dielectric relaxation have been studied to understand the dynamics of the charge carriers. Differential scanning calorimetry, X-ray diffraction and scanning electron microscopy are also done.
      PubDate: 2014-10-01
       
  • Conductivities and ion association constants of ferric chloride and
           chromic chloride in DMF and DMSO as a function of temperature
    • Abstract: Abstract The equivalent conductivities of anhydrous ferric chloride (FeCl3) and anhydrous chromic chloride (CrCl3) were measured in nonaqueous aprotic solvents such as N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) at temperatures between 278.15 and 318.15 K. In both DMF and DMSO, conductivity values for FeCl3 were found to be higher than those for CrCl3. In addition, the conductivity values for both FeCl3 and CrCl3 in DMF were higher than those in DMSO at all temperatures. The conductivity data were analyzed by the Robinson–Stokes equations. The limiting equivalent ionic conductivities for ferric ion (Fe3+) and chromic ion (Cr3+) and the ion association constants (K A ) for FeCl3 and CrCl3 were determined in DMF and DMSO. The K A values calculated for both FeCl3 and CrCl3 in DMF were higher than those in DMSO. This can be ascribed to an increase of the ion association constants with a decrease of the relative permittivity of solvents used in this study. The K A values increased with the increase in temperature in the studied solvents. Thermodynamic functions (Gibbs’ free energy, entropy, and enthalpy of ion association) were estimated from the temperature dependence of the ion association constant. The positive values of entropy and enthalpy found for FeCl3 and CrCl3 at all temperatures indicate that the association process in DMF and DMSO is endothermic.
      PubDate: 2014-10-01
       
  • Li2MnSiO       class="a-plus-plus">4/carbon nanofiber cathodes
           for Li-ion batteries
    • Abstract: Abstract Pure single-phase Li2MnSiO4 nanoparticle-embedded carbon nanofibers have been prepared for the first time via a simple sol-gel and electrospinning technique. They exhibit an improved electrochemical performance over conventional carbon-coated Li2MnSiO4 nanoparticle electrodes, including a high discharge capacity of ∼200 mAh g−1, at a C/20 rate, with the retention of 77 % over 20 cycles and a 1.6-fold higher discharge capacity at a 1 C rate.
      PubDate: 2014-10-01
       
  • Starch-based gel electrolyte thin films derived from native sago (       class="a-plus-plus">Metroxylon sagu) starch
    • Abstract: Abstract Starch-based gel electrolyte (SbGE) thin films were prepared by mixing native sago starch with different amounts of glycerol, and subsequently doped with various types of ionic salts. SbGE thin films showed substantially enhanced mechanical properties and ionic conductivity through incorporating optimal composition of native sago starch, glycerol, and ionic salts. A maximum room temperature ionic conductivity of the order of 10−3 S cm−1 was achieved for optimized SbGE thin film consisting of 80 wt% of native sago starch and 20 wt% of glycerol, and doped with 8 wt% of LiCl. SbGE thin films were characterized by Fourier transformed infrared spectrometry, scanning electron microscopy, and electrochemical impedance spectroscopy. Due to their favorable mechanical properties, high ionic conductivity at room temperature, ease of preparation, environmentally benign, and cheap, SbGE thin films show high potential utility as gel electrolyte materials for the fabrication of solid-state electrochemical devices.
      PubDate: 2014-10-01
       
  • Solid-state synthesis of graphite carbon-coated Li       class="a-plus-plus">4Ti       class="a-plus-plus">5O       class="a-plus-plus">12 anode for lithium ion
           batteries
    • Abstract: Abstract Graphites are widely used for their high electrical conductivity and good thermal and chemical stability. In this work, graphitic carbon-coated lithium titanium (Li4Ti5O12/GC) was successfully synthesized by a simple one-step solid-state reaction process with the assistance of sucrose without elevating sintering temperature. The lattice fringe of 0.208 nm clearly seen from the high-resolution transmission electron microscopy (HRTEM) images was assigned to graphite (010). The average grain size of the as-prepared Li4Ti5O12/GC was about 100–200 nm, 1 order smaller than that of pure Li4Ti5O12 prepared similarly. The rate performance and cycle ability were significantly improved by the hybrid conducting network formed by graphitic carbon on the grains and amorphous carbon between them. The specific capacity retention rate was 66.7 % when discharged at a rate of 12C compared with the capacity obtained at 0.5C. After 300 cycles, the capacity retention was more than 90 % at a high rate of 15C.
      PubDate: 2014-10-01
       
  • Effect of Ni/Mn ratio on the performance of LiNi       class="a-plus-plus">        class="a-plus-plus">x Mn       class="a-plus-plus">2 − 
                   class="a-plus-plus">x O4 cathode
           material for lithium-ion battery
    • Abstract: Abstract Lithium nickel manganate is recognized as a type of promising cathode material for lithium-ion battery, due to its advantages such as high voltage, high power density, and relative lower cost. In this paper, a series of LiNi x Mn2 − x O4 cathode materials with various molar ratio of Ni/Mn have been prepared with a co-precipitation method, followed by a solid state reaction, and the effect of the molar ratio of Ni/Mn on the structure and properties of materials are intensively investigated by means of X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), and performance measurements, etc. It is revealed that all the samples with x from 0 to 0.5 have well-defined spinel structure and fit well to Fd-3 m space group. With the increase of the molar ratio of Ni/Mn, the diffraction peaks shift to higher angle slightly and the lattice parameter decreases gradually by the XRD results. Furthermore, it is found that the capacity at the 4.0 V plateau decreases while the capacity at 4.7 V plateau increases with the increase of the ratio of Ni/Mn, and the total discharge capacity shows growth trend with the increase of Ni content. It is important that all the samples with various molar ratio of Ni/Mn exhibit good cyclic stability. Based on the experimental results, we suggest that the Ni may incorporate into the lattice of LiMn2O4 substituting of Mn. The plateau at 4.7 V is related to the Ni ions and the plateau at 4.0 V is related to the Mn ions in the materials.
      PubDate: 2014-10-01
       
  • AC impedance studies on proton-conducting PAN : NH       class="a-plus-plus">4SCN polymer electrolytes
    • Abstract: Abstract Solid polymer electrolytes based on polyacrylonitrile (PAN) doped with ammonium thiocyanate (NH4SCN) in different molar ratios of polymer and salt have been prepared by solution-casting method using DMF as solvent. The increase in amorphous nature of the polymer electrolytes has been confirmed by XRD analysis. A shift in glass transition temperature (T g) of the PAN : NH4SCN electrolytes has been observed from the DSC thermograms which indicates the interaction between the polymer and the salt. From the AC impedance spectroscopic analysis, the ionic conductivity has been found to increase with increasing salt concentration up to 30 mol% of NH4SCN beyond which the conductivity decreases and the highest ambient temperature conductivity has been found to be 5.79 × 10−3 S cm−1. The temperature-dependent conductivity of the polymer electrolyte follows an Arrhenius relationship which shows hopping of ions in the polymer matrix. The dielectric loss curves for the sample 70 mol% PAN : 30 mol% NH4SCN reveal the low-frequency β-relaxation peak pronounced at high temperature, and it may be caused by side group dipoles. The ionic transference number of polymer electrolyte has been estimated by Wagner’s polarization method, and the results reveal that the conductivity species are predominantly ions.
      PubDate: 2014-10-01
       
  • Ion transport properties of NaPF       class="a-plus-plus">6- and NaCl-doped poly(       class="a-plus-plus">N-phenylene        class="a-plus-plus">N′imino pentyl)imminium
           propane sulfonate
    • Abstract: Abstract New polymer-salt systems have been prepared by doping synthesized poly(N-phenylene N′imino pentyl) imminium propane sulfonate with NaPF6 and NaCl. The higher conductivity of the NaPF6-doped system in comparison to the NaCl-containing sample indicated that a larger-sized anion is facilitating ion conduction. FTIR spectra confirmed the complexation of salt with polymer. The conductivity power law exponent, studied in the frequency range from 42 Hz to 5 MHz, varies with frequency and has values >1, demonstrating dominance of caged ion movement. The dominance of caged motion is more pronounced in the NaCl-doped sample, signifying that a smaller anion has greater chances of being caged. Anion size signature is also visible in temperature and humidity dependence of exponent n.
      PubDate: 2014-10-01
       
  • Nanostructured base electrochemical sensor for voltammetric determination
           of homocysteine using a modified single-walled carbon nanotubes paste
           electrode
    • Abstract: Abstract A carbon paste electrode modified with benzoylferrocene (BF) and carbon nanotubes (CNTs) have been applied to the electrocatalytic oxidation of homocysteine which reduced the overpotential by about 165 mV with an obvious increase in the current response. The transfer coefficient (α) for the electrocatalytic oxidation of homocysteine and diffusion coefficient of this substance under the experimental conditions were also investigated. In a phosphate buffer solution (PBS) of pH 7.0, the oxidation current increased linearly with two concentration intervals of homocysteine; one is 0.1 to 10.0 μM, and the other is 10.0 to 80.0 μM. The detection limit (3σ) obtained by square wave voltammetry (SWV) was 50.0 nM. The proposed method was successfully applied to the determination of homocysteine in real samples.
      PubDate: 2014-10-01
       
  • Optimized AC conductivity correlated to structure, morphology and thermal
           properties of PVDF/PVA/Nafion composites
    • Abstract: Abstract Polyvinylidene fluoride (PVDF) and polyvinyl alcohol (PVA) composites were prepared by controlled loading of Nafion (5 to 15 wt%) by solution casting using water and dimethylformamide (DMF) as a solvent. The surface morphology of composite analyzed by atomic force microscopy (AFM) reveals the presence of Nafion ionomers. The increase in interlayer spacing of modified PVDF/PVA polymer system as a function of Nafion was detected by X-ray diffraction (XRD). The major change in Fourier transform infrared (FTIR) spectroscopy confirms the chemical bond C=O stretching around 1,700 cm−1 due to Nafion. Differential scanning calorimetry (DSC) demonstrates the thermal stability of polymer composites and the decrease in melting temperature (T m). The optimized AC conductivity (σ) of the prepared composite was evaluated by using an impedance analyzer as a function of temperature (40 to 150 °C) at constant 30-MHz frequency. The highest conductivity of 1.3 × 10−2 S m−1 was observed at 80 °C for 10 wt% of Nafion and correlated with structure, morphology and thermal properties of modified PVDF/PVA/Nafion composites. The experimental results may be useful for sensors, fuel cells and battery application domains.
      PubDate: 2014-10-01
       
  • Electrical properties of Li-based NASICON compounds doped with yttrium
           oxide
    • Abstract: Abstract In the present study, the electrical properties of lithium-based Li1.3Al0.3 − x Y x Ti1.7(PO4)3 (LAYTP) system is reported. Yttrium is a rare earth element and has been found to be an excellent sintering aid in ceramic electrode materials. Earlier attempts to replace the tetravalent Ti4+ using trivalent cations like Al3+, Y3+, In3+, and Sc3+ in rhombohedral NASICON structure have resulted in enhanced electrical conductivity. The effect of trivalent cation Y3+ doping in an optimized system Li1.3Al0.3Ti1.7(PO4)3 (LATP) is discussed. The electrical properties of this ceramic compound in temperature range of 303 to 423 K and in the microwave frequency range of 20 MHz to 1 Hz were studied for the LAYTP system using impedance spectroscopy. The role of yttrium to improve the density of the material and thereby the study of the grain and grain boundary is explored.
      PubDate: 2014-10-01
       
  • Influence of Gd3+ and
           Dy3+ co-doping and
           sintering regime on enhancement of electrical conductivity of ceria-based
           solid electrolyte
    • Abstract: Abstract In order to improve the conductivity of ceria-based solid electrolytes, effect of co-doped Gd3+ and Dy3+ was evaluated. For this purpose, nano-crystalline Gd0.2 − x Dy x Ce0.8O1.9 powders with various composition ranges (x = 0.05, 0.1, 0.15, 0.2) were initially synthesized by high-energy milling method. The effect of micro-structural evolution and co-doping on electrical properties of the dense sintered samples fabricated by two-step sintering and conventional sintering of the synthesized powders were investigated. Electrical conductivity of the samples was discussed based on the results obtained by AC impedance spectroscopy at temperatures in the range of 300–700 °C. The co-doping and sintering regime were found to significantly influence the conductivity of the electrolytes. The electrical conductivity of the co-doped samples depends on Dy3+ content and the maximum conductivity obtained by 0.15 mol% Dy and 0.05 mol% Gd. The conductivity of Gd0.2 − x Dy x Ce0.8O1.9 (x = 0.15) was 0.03 S/cm at 700 °C. A thorough discussion was made, based on the present experimental data.
      PubDate: 2014-10-01
       
  • Synthesis, surface characterization and electrochemical properties of
           PVC-based cerium(IV) sulphate ion exchange composite membrane
    • Abstract: Abstract The characterization of polyvinyl chloride (PVC)-based cerium(IV) sulphate (CS) composite membrane was carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composite membrane with 0.175 g PVC and 0.375 g CS proves good chemical, mechanical and thermal stabilities as well as ion exchange capacity. The Teorell, Meyer and Sievers (TMS) method was used to determine the electrochemical parameters such as transport number, mobility ratio and surface charge density of the membrane. The mobility ratio of various univalent electrolytes depends on the electrolyte concentration and follows the decreasing order LiCl > NaCl > KCl. This membrane may be used for treatment of food industry wastewater as well as desalination of sea and brackish waters.
      PubDate: 2014-09-25
       
  • Low-temperature sintering effects on NASICON-structured LiSn       class="a-plus-plus">2P       class="a-plus-plus">3O       class="a-plus-plus">12 solid electrolytes
           prepared via citric acid-assisted sol-gel method
    • Abstract: Abstract LiSn2P3O12 with sodium (Na) super ionic conductor (NASICON)-type rhombohedral structure was successfully obtained at low sintering temperature, 600 °C via citric acid-assisted sol-gel method. However, when the sintering temperature increased to 650 °C, triclinic structure coexisted with the rhombohedral structure as confirmed by X-ray diffraction analysis. Conductivity–temperature dependence of all samples were studied using impedance spectroscopy in the temperature range 30 to 500 °C, and bulk, grain boundary and total conductivity increased as the temperature increased. The highest bulk conductivity found was 3.64 × 10−5 S/cm at 500 °C for LiSn2P3O12 sample sintered at 650 °C, and the lowest bulk activation energy at low temperature was 0.008 eV, showing that sintering temperature affect the conductivity value. The voltage stability window for LiSn2P3O12 sample sintered at 600 °C at ambient temperature was up to 4.4 V. These results indicated the suitability of the LiSn2P3O12 to be exploiting further for potential applications as solid electrolytes in electrochemical devices.
      PubDate: 2014-09-25
       
  • Synthesis and performance of Li       class="a-plus-plus">2NiTi       class="a-plus-plus">3O       class="a-plus-plus">8 as a new anode material for
           lithium-ion batteries
    • Abstract: Abstract The titanate spinel Li2NiTi3O8 is proposed for the first time as a new anode for lithium-ion batteries and successfully synthesized via a facile ball-milling assisted solid-state reaction method. The sample is characterized by X-ray diffraction patterns (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), galvanostatic charge–discharge tests, cyclic voltammetry (CV) tests, and electrochemical impedance spectroscopy (EIS). The results reveal that the Li2NiTi3O8 nanoparticles have well-distributed morphology, and the particle size ranges between 100 and 300 nm. Although the initial coulombic efficiency is only 56.3 %, the Li2NiTi3O8 electrode still exhibits a high rate capability and excellent cycling stability. The Li2NiTi3O8 anode provides a large capacity of 212.3 mAh g−1 at 0.1 A g−1 after 10 cycle, which is close to its theoretical capacity (223.6 mAh g−1). Even after 100 cycles, it still delivers a quite high capacity of 203.98 mAh g−1, with no significant capacity fading. This indicates that the as-synthesized Li2NiTi3O8 material is a promising anode material for lithium-ion batteries.
      PubDate: 2014-09-05
       
 
 
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