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ENGINEERING (1120 journals)            First | 2 3 4 5 6 7 8 9 | Last

International Journal of Intelligent Engineering Informatics     Hybrid Journal  
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: 7)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (Followers: 9)
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: 4)
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: 8)
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: 3)
International Journal of Polymer Science     Open Access   (Followers: 16)
International Journal of Precision Engineering and Manufacturing     Hybrid Journal   (Followers: 7)
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: 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: 3)
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: 2)
International Journal of Spray and Combustion Dynamics     Full-text available via subscription   (Followers: 5)
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: 1)
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: 5)
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  
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 2)
Irrigation and Drainage Systems     Hybrid Journal  
ISA Transactions     Full-text available via subscription  
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: 8)
Journal of Aerosol Science     Hybrid Journal   (Followers: 2)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 112)
Journal of Alloys and Compounds     Hybrid Journal   (Followers: 6)
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: 138)

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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  [2208 journals]   [SJR: 0.522]   [H-I: 25]
  • Lithium electrochromic properties of atmospheric pressure plasma
           jet-synthesized tungsten/molybdenum-mixed oxide films for flexible
           electrochromic device
    • Abstract: Abstract An investigation is conducted into the enhanced lithium electrochromic performance of flexible tungsten/molybdenum-mixed oxide (WMo x O y C z ) films deposited onto 40 Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates, using a low temperature (~23 °C) atmospheric pressure plasma-enhanced chemical vapor deposition with an atmospheric pressure plasma jet at various substrate distances. The rapid synthesis of flexible WMo x O y C z films is performed by injecting the mixed hexacarbonyl and precursors W(CO)6 and Mo(CO)6 into an air plasma jet and exposing the substrate in the plasmas for short exposure durations (19–34 s) at various substrate distances. The flexible WMo x O y C z films possess the remarkable Li+ ion electrochromic performance, even though after being bent 360° around a 2.5-cm diameter rod for 1,000 cycles and tested for 200 cycles of reversible Li+ ion intercalation and deintercalation in a 1-M LiClO4-propylene carbonate electrolyte, respectively, by a potential sweep switching at the scan rates of ±50 mV/s from the potential of −1 to 1 V and a potential step switching at the potentials of −1 and 1 V. Significant optical modulation and optical density change of up to 71.2 % and 0.73 at a wavelength of 622 nm are respectively achieved.
      PubDate: 2014-08-01
  • Spontaneous stress-induced oxidation of Ce ions in Gd-doped ceria at room
    • Abstract: Abstract Cerium oxides are widely used within catalysis and fuel cells. The key parameters of interest, including catalytic activity, transport properties and defect structure are all fundamentally linked to the oxidation state of the cerium ions within the material which can adopt a 3+ or 4+ oxidation state. We use Raman spectroscopy, as well as scanning and optical microscopy to show that the oxidation state of cerium ions within Ce0.8Gd0.2O2−x can be altered either through chemically induced strain (imparted during processing), mechanical indentation, fracture or applied mechanical load. This work shows that both the chemical environment and stress state will play a role in determining the oxidation state of the cerium ions within ceria containing materials. It has been shown that the rate of oxidation of Ce0.8Gd0.2O2−x can be dramatically altered at room temperature via changing the local stress state of the material.
      PubDate: 2014-08-01
  • Electrical properties and conductivity mechanism of LiCuFe       class="a-plus-plus">2(VO       class="a-plus-plus">4)       class="a-plus-plus">3
    • Abstract: Abstract This paper reports conduction mechanism in LiCuFe2(VO4)3 over a wide range of temperatures (300 to 712 K) and frequencies (209 Hz to 5 MHz). The DC conductivity of the material is thermally activated with activation energy about 0.66 eV. In LiCuFe2(VO4)3, the electrical conductivity is probably due to the hopping of alkali lithium ion along the channel [001]. Temperature dependence of AC conductivity is studied at different frequencies. Frequency exponent s is found to decrease with increase in temperature. The results have been explained on the basis of correlated barrier hopping (CBH) model. Numerical calculations agree well with experimental results. The results show that the frequency and temperature-dependent behavior of AC conductivity of the studied materials are predominantly due to single polaron hopping.
      PubDate: 2014-08-01
  • Improvement in performance of a hyoscine butylbromide potentiometric
           sensor using a new nanocomposite carbon paste: a comparison study with
           polymeric membrane sensor
    • Abstract: Abstract Multiwalled carbon nanotubes and TiO2 nanoparticles were used for the improvement of a hyoscine butylbromide (HYBB) potentiometric carbon paste electrode response. The electrode was based on the ammonium reineckate-hyoscine ion association complex as an ion-exchange site dissolved in 2-nitrophenyloctyl ether as pasting liquid. The characteristics of the suggested potentiometric nanocomposite-modified HYBB carbon paste electrode in comparison with the PVC membrane sensor show better responses in terms of sensitivity, dynamic concentration range, detection limit, Nernstain slope, low potential drift, response time, lifetime, and mechanical stability. The electrode exhibits good selectivity for HYB ion with respect to a large number of cations. For investigation of the effects of carbon nanotubes and TiO2 nanoparticles on the conductivity property of the electrode surface, electrochemical impedance spectroscopy measurements were done. The prepared electrode was successfully applied to the determination of hyoscine butylbromide in pharmaceutical formulations and biological samples.
      PubDate: 2014-08-01
  • Conductivity of Fe       class="a-plus-plus">2O       class="a-plus-plus">3-doped YSZ
    • Abstract: Abstract Effect of 2 mol.% Fe2O3 addition on conductivity of yttria stabilized zirconia ceramics (YSZ, 6–12 mol.% Y2O3) was established. For Fe doped material, it was shown that conductivity demonstrates maximum at 10 mol.% Y2O3, and its value increases by 1.4 times. Conductivity maximum corresponds with the minimal volume of crystal lattice. Discussion of results was performed in terms of the model that assumes the control effect of hydrostatic pressure on oxygen ions diffusion.
      PubDate: 2014-08-01
  • Molecular dynamics simulations of lanthanum oxide surfaces
    • Abstract: Abstract Classical molecular dynamics was used to investigate the equilibrium state of the surface region of as-grown La2O3. It is currently thought that bulk and epitaxial thin film La2O3 surfaces exhibit amorphous structures in the as-prepared state that yield bulk crystal states upon postdeposition annealing. The focus of the study is to determine if the as-prepared surface region of La2O3 is purely amorphous as indicated from prior experimental results. Using simulation cells sufficiently large to accommodate the formation of defects, phase segregation, compositional migration, and site defects, our results show that crystalline phases are evident from simulated X-ray diffraction patterns. Although the phase of these crystallites is unresolved, we suggest that combinations of distorted hexagonal, cubic, and nonstoichiometric phases are formed in the as-prepared state prior to annealing. These crystallites likely serve as nucleation site for long-range ordered crystal growth upon annealing.
      PubDate: 2014-08-01
  • Ferrocene partition calculation in a biodiesel/water interface using
           electrochemical methods
    • Abstract: Abstract This work is a continuation of previous studies concerning the behaviour of ferrocene in a mixture of two insoluble liquids. In this paper, the system reached partition equilibrium after approximately 175 min. Electroanalytical studies were executed, and a high reproducibility was observed in a range of concentrations from 2 to 14 × 10−5 mol L−1 of ferrocene that escaped from the oil to the aqueous phase. Because ferrocene most likely occurs only in the monomeric form in both the oil and aqueous phases, it was possible to predict a partition coefficient (log P(oil/water)) of ferrocene of approximately 2.4.
      PubDate: 2014-08-01
  • Preparation and electrochemical performances of submicro-TiP       class="a-plus-plus">2O       class="a-plus-plus">7 cathode for lithium ion
    • Abstract: Abstract The TiP2O7 with a cubic 3 × 3 × 3 superstructure was synthesized by a liquid-assisted solid-state reaction, and characterized by x-ray diffraction, scanning electron microscopy, cyclic voltammogram, galvanostatic charge/discharge testing, and electrochemical impedance spectroscopy (EIS) technique. The results showed that there was only one step of intercalation into TiP2O7, corresponding to a pair redox (E Li/Li + = 2.74/2.48 V). The initial discharge capacity of TiP2O7 was 110 mAh/g at a current density of 15 mA/g, and the capacity retention was 76.12 % of the initial discharge capacity after 100 cycles. The EIS of TiP2O7 electrode consisted of two semicircles in organic electrolyte, which was attributed to SEI resistance as well as the contact resistance, and charge transfer process, respectively. A suitable model was proposed to explain the impedance response of the insertion TiP2O7 material of lithium ion batteries.
      PubDate: 2014-08-01
  • The first electrochemical sensor for determination of mangiferin based on
           an ionic liquid–graphene nanosheets paste electrode
    • Abstract: Abstract A novel carbon paste electrode modified with graphene nanosheets and an ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) was fabricated and used for the electrochemical study of mangiferin for the first time. This modified electrode offers a considerable improvement in voltammetric sensitivity toward mangiferin, compared to the bare electrode. Square wave voltammetry (SWV) exhibits a linear dynamic range from 5.0 × 10−8 to 2.0 × 10−4 M and a detection limit of 20.0 nM for mangiferin. Finally, the proposed method was successfully applied to the determination of mangiferin in real samples such as serum and urine.
      PubDate: 2014-08-01
  • Influence of hydrophilic properties on capacitive behavior of
           functionalized graphene
    • Abstract: Abstract Super-hydrophobic graphene was treated with 4-benzenediazoniumsulfonate to obtain a series of functionalized graphene (FG) with enhanced hydrophilic properties. The results from Fourier transform infrared (FT-IR) spectra and thermogravimetric (TG) analyses demonstrate that −SO3H groups are covalently anchored to functionalized graphene and alter the thermal stability of graphene-based materials. In comparison to pristine graphene (PG), functionalized graphene as prepared exhibits enhanced hydrophilic properties which can be conducted by varying the diazotization-coupling reaction time. Cyclic voltammetry (CV) curves indicate that enhanced hydrophilic properties improve the capacitance of functionalized graphene up to twice than that of pristine graphene in Na2SO4 electrolytes. Moreover, electrochemical impedance spectroscopy (EIS) reveals that the high level of functionalization will cause the decrease of the electric conductivity and capacitive performance, suggesting that functionalization of graphene provides the competitive relationship between the positive hydrophilicity increase and the negative conductivity decrease to capacitive performance.
      PubDate: 2014-08-01
  • Solvothermal synthesis and electrochemical performance of Ag-doped
           V6O       class="a-plus-plus">13 as cathode material for
           lithium-ion battery
    • Abstract: Abstract For the first time, belt-like V6O13 precursor was synthesized via a simple solvothermal method. Rod-like Ag-doped V6O13 was successfully synthesized by this method followed by heating at 350 °C. Both crystal domain size, electronic conductivity, and the lithium diffusion coefficient of the Ag-doped V6O13 samples are influenced by the added amount of AgNO3. When the amount of AgNO3 is 0.008 g, the product is rod-like particles, which are 0.1–0.3 μm wide and 1–2 μm long, and exhibits the best electrochemical performance. The enhanced electrochemical performance originates from its higher total conductivity, higher lithium diffusion coefficient, and better structural reversibility.
      PubDate: 2014-08-01
  • Thermodynamic properties and application of CBH model in the ac
           conductivity of LiNi       class="a-plus-plus">1.5P       class="a-plus-plus">2O       class="a-plus-plus">7 ceramic
    • Abstract: Abstract The LiNi1.5P2O7 compound was prepared by the solid-state reaction method at 923 K and characterized through XRD and Raman spectroscopy techniques. The impedance spectroscopy measurements were performed in the frequency and the temperature range (300 Hz–5 MHz) and (633–729 K), respectively. The ac conductivity for grain contribution is interpreted using the universal Jonscher’s power low. The exponent n decreases with increasing temperature which reveals that the conduction inside the studied material is insured by the correlated barrier hopping (CBH) model. The parameters of CBH model were determined showing that the ac conduction is realised by single-polaron hopping mechanism. Thermodynamic parameters such as the free energy for dipole relaxation ΔF, the enthalpy ΔH, and the change in entropy ΔS have been calculated.
      PubDate: 2014-08-01
  • Effect of the TiO2
           content as support with carbon toward methanol electro-oxidation in
           alkaline media using platinum nanoparticles as electrocatalysts
    • Abstract: Abstract Platinum nanoparticles supported on physical mixtures of Vulcan carbon and TiO2 (Pt/(C + TiO2)) were prepared by the borohydride method and tested for methanol electro-oxidation in alkaline media. X-ray diffraction (XRD) analyses showed peaks characteristic of Pt face-centered cubic (fcc) structure and peaks associated with TiO2 and carbon. Transmission electron microscopy (TEM) images showed the Pt nanoparticles distributed preferentially over the TiO2 support with average particle sizes between 5 and 6 nm. Cyclic voltammograms showed a decrease of Pt surface area with increasing TiO2 load while linear sweep in the presence of methanol showed Pt/(C + TiO2) (60:40) with the highest current density in accordance with chronoamperometry. The results were attributed to Pt-based nanoparticles on TiO2 which show enhanced catalytic activities for methanol oxidation due to a metal-support interaction. Furthermore, TiO2 is a semiconductor with low conductivity when compared to carbon. Thus, it is expected that an intermediate proportion of carbon and TiO2 as substrate could improve the activity of Pt nanoparticles without substantial loss of conductivity, resulting in a synergic effect.
      PubDate: 2014-08-01
  • PtRu electrocatalysts on carbon nanotubes treated by phenylphosphonic acid
           for electrooxidation of methanol
    • Abstract: Abstract Phenylphosphonic acid (PPA)-assisted one-pot method for preparation of PtRu nanoparticles with high dispersion and stabilization on carbon nanotubes (CNTs) is reported. Based on the π–π stacking between phenylphosphonic acid and CNTs, abundant phosphonate groups were uniformly introduced on CNTs' surface, which significantly not only improve the solubility and dispersibility of CNTs in polar solvents but also enhance the dispersion of PtRu nanoparticles on CNTs' surface. The obtained PtRu/PPA-CNT electrocatalysts are characterized by transmission electron microscopy, infrared spectroscopy, thermal gravimetric analysis, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray powder diffraction. The results reveal that CNTs were successfully functionalized by PPA, and PtRu nanoparticles were uniformly dispersed on PPA-CNT surface with average particle diameter of 2.5 nm. Electrochemical studies certified that PtRu/PPA-CNT electrocatalysts have much higher electrocatalytic activity and stability for methanol oxidation in comparison with PtRu nanoparticles supported on the pristine CNTs because of their highly electrochemical surface area at 612.7 cm2 mg−1.
      PubDate: 2014-08-01
  • The optimized preparation and electrochemical properties of LiMn       class="a-plus-plus">1.95Co       class="a-plus-plus">0.05O       class="a-plus-plus">4 and Al       class="a-plus-plus">2O       class="a-plus-plus">3-coated LiMn       class="a-plus-plus">1.95Co       class="a-plus-plus">0.05O       class="a-plus-plus">4
    • Abstract: Abstract Cathode material LiMn1.95Co0.05O4 for lithium ion battery was synthesized via solid state reaction, and calcination temperature and time were investigated, respectively. Thermogravimetry (TG) and differential thermal analysis (DTA) measurements were utilized to determine the calcination temperature of precursor sample. The optimized calcination temperature and time are 850 °C and 15 h. The surface of LiMn1.95Co0.05O4 cathode is coated using Al2O3 coating materials. The phase structures, surface morphologies, and element types of the prepared LiMn1.95Co0.05O4 and Al2O3-coated LiMn1.95 Co0.05O4 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy spectrum analysis (EDS). The 0.5 wt% Al2O3-coated compound exhibited better specific capacity and capacity retention than bare sample. The initial discharge capacity was 140.9 mAh/g and capacity retention was 96.7 % after 10 cycles at 0.1 C. Such enhancements are attributed to the presence of a stable Al2O3 layer which acts as the interfacial stabilizer on the surface of LiMn1.95Co0.05O4.
      PubDate: 2014-08-01
  • Electrodeposition of cobalt with tunable morphology from reverse micellar
    • Abstract: Abstract Electrodeposition of cobalt on a copper electrode was successfully performed from aqueous and reverse micellar solutions of a cationic surfactant, cetyltrimethylammonium bromide (CTAB), using constant potential electrolysis method. The potential to be applied for electrodeposition was judged from the cyclic voltammetric behavior of cobalt(II) in aqueous and reverse micellar solutions of CTAB at different compositions. The morphology, dimension, and crystallinity of cobalt deposited onto a copper substrate were evaluated from scanning electron microscopy (SEM) images and X-ray diffraction technique. The cobalt deposited on copper from aqueous solution does not show any definite shape and size, while the deposition from reverse micellar solutions occurred with definite shapes such as star-, flower-, and nanorod-like structures depending on the composition. The slow kinetics governed by the reverse micelles associated with the deposition brings about oriented growth of cobalt onto the copper substrate and offers the potential to electrochemically tune cobalt deposit with desirable morphology.
      PubDate: 2014-08-01
  • Advanced electrochemical performances of Li       class="a-plus-plus">4Ti       class="a-plus-plus">5O       class="a-plus-plus">12/Ag prepared by a facile
           synthesis route
    • Abstract: Abstract Spinel Li4Ti5O12 coated by highly dispersed nanosized Ag particles was synthesized via a facile and effective ultrasonic-assisted method in this paper. X-ray diffraction (XRD) results indicated that Ag was not doped into the lattice of spinel Li4Ti5O12. The as-synthesized Li4Ti5O12/Ag exhibited enhanced electronic conductivity and excellent electrochemical performances. Its electronic conductivity was increased about four times compared to that of the pristine Li4Ti5O12. Even at 10 C rate, the as-synthesized Li4Ti5O12/Ag could keep 86.5 % of the reversible capacity at 1 C rate and its reversible capacity was higher than 140 mAhg−1 whereas those were 75.3 % and 118 mAhg−1 for the pristine Li4Ti5O12.
      PubDate: 2014-08-01
  • Microstructural and electrochemical properties of rf-sputtered
           LiFePO4 thin films
    • Abstract: Abstract LiFePO4 has been synthesized by hydrothermal synthesis. A 2-in. sputtering target has been prepared using synthesized powder and employed for the deposition of LiFePO4 films by radio frequency magnetron sputtering. Microstructural properties have been studied by using X-ray diffraction, Raman spectroscopy, and atomic force microscope. The films deposited at 350 °C with subsequent annealing at 600 °C for 4 h exhibited well-crystallized peaks along with (101) predominant orientation which corresponds to orthorhombic olivine-type structure with Pnma space group. The electrochemical properties have been studied for films in aqueous as well as in non-aqueous media. Both the electrochemical cells at same current density of 20 μA/cm2 delivered the same initial discharge capacity around 38 μAh/cm2 μm. The Li//LiFePO4 cell exhibited good cycling stability for the first 20 cycles.
      PubDate: 2014-08-01
  • Studies of the electrochemical properties and thermal stability of
           LiNi1/3Co       class="a-plus-plus">1/3Mn       class="a-plus-plus">1/3O       class="a-plus-plus">2/LiFePO       class="a-plus-plus">4 composite cathodes for
           lithium ion batteries
    • Abstract: Abstract A series of LiNi1/3Co1/3Mn1/3O2/LiFePO4 composite cathodes with the LiFePO4 mass content ranging from 10 to 30 wt% were prepared by ball milling in order to combine the merits of layered LiNi1/3Co1/3Mn1/3O2 and olivine LiFePO4. The structure and morphology of the samples were characterized by X-ray diffraction and scanning electron microscope. The composite cathodes exhibited improved electrochemical performance compared with pristine LiNi1/3Co1/3Mn1/3O2. Among all the composite cathodes, the one with 20 wt% of LiFePO4 showed the best electrochemical performance in terms of discharge capacity, cycle stability, and rate capability. Electrochemical impedance spectroscopy showed that mixing of LiFePO4 in LiNi1/3Co1/3Mn1/3O2 decreased the internal resistance of the electrode, retarded the formation of SEI film, and facilitated the charge transfer reaction. Differential scanning calorimetry showed that the composite cathode had better thermal stability than pristine LiNi1/3Co1/3Mn1/3O2.
      PubDate: 2014-08-01
  • Effect of nano-composite on polyvinyl alcohol-based proton conducting
           membrane for direct methanol fuel cell applications
    • Abstract: Abstract Novel composite membranes composed of polyvinyl alcohol (PVA) as host with montmorillonite (MMT) were prepared by solution casting method. A maximum conductivity of 0.9527 S cm−1 was obtained at room temperature for the composite membrane of PVA (80)-H+MMT(20). Fourier transform infrared spectroscopy (FTIR) studies confirmed the functional groups present in the membranes. The exfoliation of composite material in polymer matrix was analyzed by X-ray diffraction (XRD) technique. The results of ion exchange capacity (IEC), water/methanol uptake, and swelling measurements were presented. The scanning electron microscopy (SEM) result also revealed uniform and homogeneous mixture of nano-composite particle of MMT. Simultaneous thermal analysis (STA) curves exposed an excellent thermal stability. Moreover, the conductivity results indicate that the prepared PVA/MMT composite membranes have a good electrochemical performance for recent trends in energy research. It is noticed that the low methanol uptake for the prepared membrane is a good candidate for the fuel cell applications.
      PubDate: 2014-07-27
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