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ENGINEERING (1208 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 5)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 226)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 7)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Artificial Neural Systems     Open Access   (Followers: 4)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 25)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 25)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 37)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 29)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 9)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 3)
Applied Nanoscience     Open Access   (Followers: 7)
Applied Network Science     Open Access  
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arid Zone Journal of Engineering, Technology and Environment     Open Access   (Followers: 2)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 3)
Batteries     Open Access   (Followers: 4)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 9)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 32)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 3)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 14)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 41)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Thermal Engineering     Open Access   (Followers: 3)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 5)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 4)
Coatings     Open Access   (Followers: 3)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 26)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 253)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 178)
Composites Part B : Engineering     Hybrid Journal   (Followers: 227)
Composites Science and Technology     Hybrid Journal   (Followers: 184)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 13)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 28)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 10)
Computing and Visualization in Science     Hybrid Journal   (Followers: 5)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 30)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 8)
Control Engineering Practice     Hybrid Journal   (Followers: 42)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 25)
CT&F Ciencia, Tecnologia y Futuro     Open Access  

        1 2 3 4 5 6 7 | Last

Journal Cover Current Applied Physics
  [SJR: 0.716]   [H-I: 55]   [4 followers]  Follow
   Full-text available via subscription Subscription journal
   ISSN (Print) 1567-1739
   Published by Elsevier Homepage  [3042 journals]
  • Large grained and high charge carrier lifetime CH3NH3PbI3 thin-films:
           implications for perovskite solar cells
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Arun Singh Chouhan, Naga Prathibha Jasti, Shreyash Hadke, Srinivasan Raghavan, Sushobhan Avasthi
      Spin coated perovskite thin films are known to have an issue of pinholes & poor morphology control which lead to poor device-to-device repeatability, that is an impediment to scale-up. In this work, Methylamine vapor annealing process is demonstrated which consistently leads to high-quality perovskite thin-films with an average grain-size of 10–15 μm. The improvement in film morphology enables improvement in effective carrier recombination lifetime, from 21 μs in as-deposited films to 54 μs in vapor-annealed films. The annealed films with large-grains are also more stable in ambient conditions. Devices made on annealed perovskite films are very consistent, with a standard deviation of only 0.7%. Methylamine vapor annealing process is a promising method of depositing large-grain CH3NH3PbI3 films with high recombination lifetime and the devices with improved performance.
      Graphical abstract image

      PubDate: 2017-07-21T01:48:09Z
  • Impact of average photon-energy coefficient of solar spectrum on the short
           circuit current of photovoltaic modules
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Yuhei Horio, Md. Mijanur Rahman, Yurei Imai, Yoshihiro Hishikawa, Takashi Minemoto
      The output energy of photovoltaic (PV) modules is influenced by the spectral irradiance distribution of the solar spectrum under outdoor conditions. To rate the precise output energy of PV modules, the correction of short circuit current (I SC) based on actual environmental conditions is needed, because I SC significantly depends on the shape of the spectral irradiance distribution. The average photon energy (APE) is a zero-dimensional index for spectral irradiance distribution, and APE value uniquely describes the shape of a solar spectrum. Thus, APE has an impact on I SC of PV modules. In this contribution, the relationship between APE coefficient and I SC of the multi-crystalline silicon, single-crystalline silicon, heterojunction intrinsic thin-layer, back contact, copper indium selenide and cadmium telluride PV modules has explored. It is revealed that APE value changes the I SC of PV modules which appeared to have immense possibilities of I SC correction using APE coefficient. This new approach can be very effective for precise rating the output energy of PV modules under actual outdoor conditions.

      PubDate: 2017-07-21T01:48:09Z
  • MOFs-derived carbon covered alumina (CCA) supported Pt nanoparticles as
           catalyst for enantioselective hydrogenation
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Xueqin Zhang, Wencheng Tu, Meitian Xiao, Yongjun Liu, Jing Ye
      A one-step approach was developed to prepare carbon covered alumina (CCA) material by using Al-based MOFs (Al-PCP) as sacrificial template. Pt/CCA nanoparticle catalysts were characterized by using XRD, TGA, XPS, N2 sorption, SEM, TEM and elemental analysis and revealed that they retained the mesostructure with high Pt dispersion and had a CCA structure. Moreover, after reduced at 800 °C, Pt/CCA-800 afforded the highest enantiomeric excess (84.8%) after chirally modified with cinchonidine at the second time reaction and can be recycled for more than 8 times without distinct loss of activity or enantioselectivity in the asymmetric hydrogenation of ethyl 2-oxo-4-phenylbutyrate.
      Graphical abstract image

      PubDate: 2017-07-21T01:48:09Z
  • Fabrication and device characterization of potassium fluoride solution
           treated CZTSSe solar cell
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Tanka Raj Rana, JunHo Kim, Jun-Hyoung Sim, Kee-Jeong Yang, Dae-Hwan Kim, Jin-Kyu Kang
      Post deposition treatment (PDT) for Cu2ZnSn(S,Se)4 (CZTSSe) was carried out by simply dipping the absorber into the KF solution at 80 °C. The dipping time of absorber in KF solution was found to be crucial to device parameters of CZTSSe solar cell. The K-doping improved the solar cell efficiency from 4.4% to 7.6% by 1 min dipping whereas the longer than 5 min dipping solar cells showed distorted kink J-V curves. The activation energy of CZTSSe solar cell was increased upto 1 min KF treatment from 0.83 eV to 0.92 eV which indicates interface recombination is reduced significantly. However, the activation energies of 5 min and 10 min dipping solar cells were found to be 0.81 eV and 0.63 eV where dominant recombination was interface recombination. Furthermore, trap energies of 49 meV and 298 meV of pristine CZTSSe solar cell were modified to 33 meV and 117 meV for 1 min treated CZTSSe solar cell. Trap energies of 5 min were calculated to be 112 meV and 147 meV. The proper KF doping passivated the shallow as well as deep defects of CZTSSe solar cell which is reflected in photovoltaic performances directly.

      PubDate: 2017-07-21T01:48:09Z
  • Effect of thermal annealing sequence on the crystal phase of HfO2 and
           charge trap property of Al2O3/HfO2/SiO2 stacks
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Heedo Na, Juyoung Jeong, Jimin Lee, Hyunsu Shin, Sunghoon Lee, Hyunchul Sohn
      In this study, we investigated the effect of a post annealing sequence on the HfO2 crystal phase and the memory window of charge trap devices with TiN-Al2O3-HfO2-SiO2-Si stacks. The charge trap dielectrics of HfO2 were deposited by atomic layer deposition and were annealed in an oxygen environment with or without Al2O3 blocking oxides. X-ray diffraction analysis showed that, after thermal annealing, the predominant crystal phase of HfO2 is divided into tetragonal and monoclinic phase depending on the presence or absence of Al2O3 blocking oxide. In addition, deconvolution of X-ray diffraction spectra showed that, with increasing annealing temperature, the fraction of the tetragonal phase in the HfO2 film was enhanced with the Al2O3 blocking oxide, while it was reduced without the Al2O3 blocking oxide. Finally, measurements of program/erase and increase-step-pulse programming showed that the charge trap efficiency and the memory window of the charge trap devices increased with decreasing fraction of tetragonal HfO2.
      Graphical abstract image

      PubDate: 2017-07-21T01:48:09Z
  • Enhancing the electrical conductivity and thermoelectric figure of merit
           of the p-type delafossite CuAlO2 by Ag2O addition
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Sarayut Pantian, Rachsak Sakdanuphab, Aparporn Sakulkalavek
      (CuAlO2)1-x(Ag2O)x specimens with 0 ≤ x ≤ 0.06 were prepared through the sintering of mixtures of CuO, Al2O3 and Ag2O powders at 1373 K. Hall effect, Seebeck coefficient and electrical conductivity measurements were subsequently employed to assess the electrical transport properties. The electrical conductivity of the as-sintered samples was found to increase with Ag2O addition as a result of increases in the carrier density. Over the temperature range of 323–623 K, the transport properties can be attributed to thermally activated transitions from the acceptor state to the valence band. In contrast, the variable range hopping theory is applicable over the temperature range of 623–873 K. Ag2O addition evidently reduces the defect binding energy in the electronic structure of the CuAlO2. The addition of this compound also obstructs the formation of both a spinel phase and CuO, such that the oxygen off-stoichiometry value and the carrier density are increased with increasing Ag2O levels. The presence of Ag metal has the main effect on thermal conductivity below 400 K, while above 400 K increases in the phonon concentration affect the conductivity. The highest value obtained for the figure of merit was 0.0044 at 573 K, from a sample containing 0.2 at.% Ag2O.
      Graphical abstract image

      PubDate: 2017-07-08T01:21:26Z
  • Theoretical investigation of electronic, magnetic, transport and optical
           properties of the pure and doped cuprate superconductor HgBa2CuO4+δ
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Khalid Quertite, Halima Zaari, Hamid Ez-Zahraouy, Abdallah El Kenz, Hamid Oughadou, Abdelilah Benyoussef
      We report detailed DFT calculations and Monte Carlo simulations on the pure and doped cuprate superconductor HgBa2CuO4+δ. For the pure compound (δ = 0), we have obtained an insulating behavior with strong antiferromagnetic copper spin correlations in the CuO2 plane. The high value of the calculated Néel temperature T N  = 333 K reflects the large in-plane exchange interaction J = -145 meV. The obtained optical properties and critical exponents demonstrate the anisotropic quasi-2D character of this type of materials. As for the doped compound the electronic structure and the transport properties have been investigated for various values of doping. Based on these data, we suggest a prediction of the value of optimum doping for HgBa2CuO4+δ (δoptimal = 0.125).

      PubDate: 2017-07-08T01:21:26Z
  • Investigation on native defects of α-MgAgSb and its effects on
           thermoelectric properties using first principles calculations
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Zhuoyi Pang, Xiwen Zhang, Chao Wang
      α-MgAgSb is a promising thermoelectric materials having good performance at medium temperature. Native defects in α-MgAgSb are frequently reported experimentally and are tightly involved in the thermoelectric properties of α-MgAgSb. In this paper, all possible native defects in α-MgAgSb are calculated as well as detailed results are given and discussed. The concentrations of several dominant native defects, for example, V Ag and Ag Sb , could reach up to 10−4 cm−3 at 540 K. Furthermore, the electronic structure and transport properties of α-MgAgSb with dominant native defects are investigated. Results show that the introduction of Ag Mg and V Ag contributes to a much lower inertial mass and slight decrease in Seebeck coefficient. The lattice thermal conductivity is greatly reduced with the introduction of native defects. For α-MgAgSb with V Ag , the peak ZT could reach up to 1.84 at 420 K. Our calculation demonstrates that defect engineering is an effective strategy to enhance thermoelectric performance of the materials.

      PubDate: 2017-07-08T01:21:26Z
  • Application of electromagnetic processing for development of
           high-performance sintered powder metal parts
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Daudi R. Waryoba, Winston Roberts
      Electromagnetic processing was used to study the effects of electro-magneto forming on the dimensional control and thermal stability of sintered powder metal (PM) parts. The investigation was carried out on sinter-hardened, low chromium-molybdenum bainitic steel. The results show an increase in the microhardness of about 14% for the electromagnetic processed parts compared to the as-sintered parts. This was attributed to the 2% increase in the density, 17% and 29% reduction in the volume fraction of porosity and width of the bainitic lath, respectively, due to the electromagnetic processing. Dimensional characterization was carried out using a vertically aligned push-rod dilatometer. After four thermal cycles of heating and cooling, at a controlled rate of 5 °C/min to 1000 °C, the electromagnetic processed parts exhibited reduced dimensional change of about 44% lower than for the as-sintered parts. This is significantly important for applications that demand high dimensional tolerance and performance, especially at elevated temperatures.

      PubDate: 2017-07-08T01:21:26Z
  • Modeling and simulation of efficiency droop in GaN-based blue
           light-emitting diodes incorporating the effect of reduced active volume of
           InGaN quantum wells
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Han-Youl Ryu, Guen-Hwan Ryu, Young-Hwan Choi, Byungjin Ma
      The efficiency droop of InGaN-based blue light-emitting diodes (LEDs) is analyzed using numerical simulations with a modified ABC carrier recombination model. The ABC model is modified to include the effect of reduced effective active volume of InGaN quantum wells (QWs) and incorporated into the numerical simulation program. It is found that the droop of internal quantum efficiency (IQE) can be well explained by the effect of reduced light-emitting active volume without assuming a large Auger recombination coefficient. A simulated IQE curve with the modified ABC model is found to fit quite well with a measured efficiency curve of an InGaN LED sample when the effective active volume takes only 2.5% of the physical volume of QWs. The proposed numerical simulation model incorporating the reduced effective active volume can be advantageous for use in the modeling and simulation of InGaN LEDs for higher efficiency.

      PubDate: 2017-07-08T01:21:26Z
  • Effect of annealing treatment on the uniformity of CeO2/TiO2 bilayer
           resistive switching memory devices
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): M. Ismail, A.M. Rana, S.-U. Nisa, F. Hussain, M. Imran, K. Mahmood, I. Talib, E. Ahmed, D.H. Bao
      Bilayer CeO2/TiO2 films with high-k dielectric property were prepared by rf magnetron sputtering technique at room temperature. Effect of annealing treatment on resistive switching (RS) properties of bilayer CeO2/TiO2 films in O2 ambient at different temperature in the range of 350–550 °C was investigated. Our results revealed that the bilayer films had good interfacial property at 500 °C and this annealing temperature is optimum for different RS characteristics. Results showed that bilayer CeO2/TiO2 film perform better uniformity and reliability in resistive switching at intermediate temperature (i.e. 450 °C and 500 °C) instead of low and high annealing temperature (i.e. 350 °C and 550 °C) at which it exhibits poor crystalline structure with more amorphous background. Less Gibbs free energy of TiO2 as compared to CeO2 results in an easier re-oxidation of the filament through the oxygen exchange with TaN electrode. However, the excellent endurance property (>2500 cycles), data retentions (105 s) and good cycle-to-cycle uniformity is observed only in 500 °C annealed devices. The plots of cumulative probability, essential memory parameter, show a good distribution of Set/Reset voltage.

      PubDate: 2017-07-08T01:21:26Z
  • The hyperconjugation effect on the graphene counterparts based on silicon
           and germanium
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Hassan Chataoui, Hasna Choukri, Mohamed Maatallah, Driss Cherqaoui, Abdellah Jarid
      Bending of the A = A (A of the group IVA) double bond neighboring is rationalized by the hyperconjugation phenomenon analysis. The bending is also observed for the high sized linear, cyclic or graphene-like compounds that imply the conjugated double bonds. The electronic delocalization takes place between occupied σ(π) and unoccupied π*(σ*) orbitals especially for compound implying Si and Ge atoms. Leading to rippled structure, this phenomenon affects the silicene and germane thickness sheets and probably would have some consequences on the properties of such compounds when they will be involved in the industries in the future. However we introduce a new parameter to assess the thickness of graphenic structures when the hyperconjugation takes place in the bonding framework. The study has been undertaken at high levels of theory like B3LYP/6-311 + G(3df,2p).

      PubDate: 2017-07-08T01:21:26Z
  • Theoretical insight into the carrier mobility anisotropy of hole transport
           material Spiro-OMeTAD
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Guanghao Meng, Yantao Shi, Xuedan Song, Min Ji, Yuan Xue, Ce Hao
      All-solid-state organic-inorganic halide perovskite solar cells (PSCs) have attracted wide attention due to the rapid progress of power conversion efficiency in recent years. Hole transport material (HTM) in PSCs plays the role of extracting and transporting photo-excited holes. Anisotropy of carrier mobility is one important property for semiconductors, however, which still remains unclear for the dominant HTM spiro-OMeTAD used in PSCs. Based on Density Functional Theory (DFT) and Marcus theory, we for the first time conducted investigations on the anisotropy of carrier mobility along representative crystal planes of spiro-OMeTAD by recombination energy λ and electronic coupling integral V. Results indicate that the holes and electrons show transport orientations consistency parallel to the (010), (101) and (111) crystal planes while inconsistency was found parallel to (100), (110), (011) and (001) crystal planes (with an angle ranged from 40° to 70° between the hole and electron transport directions). Our work embodies the theoretical significance of controllable and oriented fabrication of HTM in PSCs.
      Graphical abstract image

      PubDate: 2017-07-08T01:21:26Z
  • Molecular dynamics study of the shear strength and fracture behavior of
           nanoporous graphene membranes
    • Abstract: Publication date: Available online 6 July 2017
      Source:Current Applied Physics
      Author(s): Te-Hua Fang, Zhe-Wei Lee, Win-Jin Chang
      We perform molecular dynamics (MD) simulations to study the structural response and fracture characteristics of nanoporous graphene (NPG) membranes subjected to shear loading. The effects of porosity, temperature, and shear velocity on the mechanical responses of NPG membranes are examined. The results show that the wrinkling of the membrane becomes more obvious with increasing strain. Fractures occur around holes on the long diagonal of the NPG parallelogram, and fracture stress in the NPG membrane decreases with increasing porosity. In addition, the effect of shear velocity on the shear modulus decreases with increasing porosity. The fracture strain of NPG membranes with different porosities obviously decreases with increasing temperature. The results enhance our understanding of the shear mechanical properties of NPG membranes and are helpful for the design and application of high-performance NPG membranes.

      PubDate: 2017-07-08T01:21:26Z
  • Characterization of wafer-scale MoS2 and WSe2 2D films by spectroscopic
    • Abstract: Publication date: Available online 5 July 2017
      Source:Current Applied Physics
      Author(s): Mangesh S. Diware, Kyunam Park, Jihun Mun, Han Gyeol Park, Won Chegal, Yong Jai Cho, Hyun Mo Cho, Jusang Park, Hyungjun Kim, Sang-Woo Kang, Young Dong Kim
      Here, we present the spectroscopic ellipsometry investigation of synthetically grown wafer-scale two-dimensional (2D) MoS2 and WSe2 films to access quality and thickness uniformity. MoS2 and WSe2 samples were grown by chemical vapor deposition and atomic layer deposition, respectively. Complex dielectric function ( ε = ε 1 + i ε 2 ) and thickness information of these 2D films were extracted from the measured data using multilayer optical calculations. Broad spectral range (1.2–6 eV) and multiple angles of incidence were used to reduce correlations among fitting parameter. Lineshape of ε of MoS2 and WSe2 monolayer films are consistent with literature but shows higher values, suggests better quality of our samples. Eight-inch wafer size MoS2 monolayer sample shows ∼ 70% uniformity with an average thickness of 0.65 ± 0.2 nm, and three-layer WSe2 sample of 8 × 1 cm2 area shows ∼ 80% uniformity with an average thickness of 2.5 ± 0.4 nm. Our results will be helpful to accelerate commercialization process of 2D devices.

      PubDate: 2017-07-08T01:21:26Z
  • Topological confinement effect of edge potentials in zigzag-edge graphene
           nanoribbons under a staggered bulk potential
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Kyu Won Lee, Cheol Eui Lee
      We have investigated topological confinement effects of edge potentials on gapless edge states in zigzag-edge graphene nanoribbons (ZGNRs) under a staggered bulk potential. A variety of gapless edge states were predicted with the concept of topological confinement effect alone, which was confirmed by using tight-binding model calculations. Half-metallicity of ZGNR, which has been semiclassically described, was revealed to fundamentally result from a topological confinement effect. Edge potentials were found to allow an infinitesimal staggered bulk potential to result in gapless edge states, regardless of the ribbon width. A uniform or staggered potential applied to the boundary region narrower than a critical width was found to play a role of the edge potentials, and the critical width was estimated.

      PubDate: 2017-06-27T06:59:00Z
  • Enhancing magnetoelectric properties of 0–3 particulate composite
           ceramics by introducing nano-sized sintering aids via self-combustion
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Xiangyong Zhao, Dun Wu, Bijun Fang, Feifei Wang, Yanxue Tang, Wangzhou Shi, Jianning Ding
      The 0.55Pb(Ni1/3Nb2/3)O3-0.05PbHfO3-0.4PbTiO3/Ni0.875Zn0.125Fe2O4 (PNNHT/NZF) 0–3 particulate composite ceramics were prepared by the conventional solid-state reaction method via introducing the nano-sized WO3 and CuO sintering aids by the self-combustion method. Due to the introducing of nano-sized sintering aids, densified PNNHT/NZF composite ceramics are synthesized sintered at low sintering temperature. Furthermore, the nano-sized sintering aids act effectively as blocking layers, leading to compact composite ceramics with homogenously dispersed and isolated microstructure morphology, inhibiting inter-phase diffusion, avoiding interfacial chemical reaction, and achieving strong inter-phase coupling. Therefore, the synthesized PNNHT/NZF composite ceramics exhibit enhanced magnetoelectric properties.

      PubDate: 2017-06-27T06:59:00Z
  • Metastable argon atoms under significant neutral depletion in helicon
           plasmas by laser-induced fluorescence
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): B.H. Seo, J.H. Kim, S.J. You
      We study the spatial distribution of the metastable-state argon atoms in high density helicon plasmas by means of laser-induced fluorescence. It is observed that the neutral argon in metastable-state has an anomalous radial distribution in density; it has a caldera-like shape radially, which is rare in typical low-temperature plasmas such as inductively coupled plasmas wherein the density increases toward the discharge center, as previously reported. The formation of the distribution can be explained as it forms by the combined effects of significant neutral depletion in high plasma density, off-axis electron-density distribution, and increasing diffusive loss toward the wall. To establish the assertion with the underlying physics, we calculate a simple global model and obtain the neutral density distribution in metastable-state under various conditions. The calculated results qualitatively agree with the experimental results.

      PubDate: 2017-06-27T06:59:00Z
  • Triple-band metamaterial absorber based on single resonator
    • Abstract: Publication date: October 2017
      Source:Current Applied Physics, Volume 17, Issue 10
      Author(s): Young Ju Kim, Ji Sub Hwang, Young Joon Yoo, Bui Xuan Khuyen, Xianfeng Chen, YoungPak Lee
      The single resonator generally reveals a single absorption band, and the resonators with different sizes or shapes have to be arranged in order to achieve multi-absorption bands. We propose the triple-band metamaterial absorber by utilizing only single resonator. Meta-atoms are made of the toothed-wheel shape metallic pattern and a continuous metallic plane, separated by a dielectric layer. The first and the third absorption bands are induced by the fundamental and the third-harmonic magnetic resonances, respectively, and the second absorption band is induced by the magnetic resonance relevant to two grooves. In addition, the diffraction peak appears between the second and the third absorption bands, due to the surface currents which are separated between the upper and the lower metallic pattern parts. The proposed structure is scalable to smaller size for the infrared and the visible regimes.

      PubDate: 2017-06-27T06:59:00Z
  • Charge separation behaviors of novel AgI/BiOI heterostructures with
           enhanced solar-photocatalytic performance
    • Abstract: Publication date: September 2017
      Source:Current Applied Physics, Volume 17, Issue 9
      Author(s): Qi Yang, Jiao Huang, Junbo Zhong, Jiufu Chen, Jianzhang Li, Siyang Sun
      The photocatalytic efficiency of the bare BiOI has been greatly restricted because of the high recombination rate of electron-hole charge pairs. To further regulate the photocatalytic performance of BiOI, in this work AgI was employed to couple with BiOI. A serial of novel AgI/BiOI heterostructures with improved sunlight-driven photocatalytic activities were prepared in-situ by a hydrothermal method. The results reveal that the presence of AgI in the composites alters band gap of the samples and greatly affects the photo-induced charge separation rate benefited from the strong interaction between AgI and BiOI. ·OH and ·O2 − were observed using electron spin-resonance (ESR) spectroscopy. The photocatalytic activities of AgI/BiOI heterostructures for the decay of methyl orange (MO) and phenol solution under the simulated sunlight irradiation were investigated, the results display that the composite photocatalysts exhibit higher photocatalytic activity than the bare BiOI and excellent stability. The charge separation and transfer mechanism was proposed based on the experimental results.
      Graphical abstract image

      PubDate: 2017-06-15T06:51:29Z
  • Donor–acceptor bifunctionality of dysprosium in perovskite calcium
           copper titanate polycrystals
    • Abstract: Publication date: September 2017
      Source:Current Applied Physics, Volume 17, Issue 9
      Author(s): Gi-Young Jo, Hee-Suk Chung, Suk-Joong L. Kang, Sung-Yoon Chung
      Systematic control of electrical properties is a challenging task in polycrystalline materials having significant electrical heterogeneity. In particular, as most aliovalent dopants in oxides usually play a single role of either a donor or an acceptor, controlling the respective electronic conductance of grains and grain boundaries in a separate manner by simple doping is not easily achieved. Using the polycrystalline perovskite Ca1/4Cu3/4TiO3, the grains of which have relatively high conductance and the grain boundaries reveal much lower conductance, we demonstrate the donor–acceptor bifunctionality of dysprosium (Dy) and its impact on the variation of electrostatic potential barriers at grain boundaries. DC current–voltage measurements and impedance spectroscopy analyses consistently show that Dy selectively affects the grain-boundary conductance without a substantial change of conductance in the grains. Atomic-scale scanning transmission electron microscopy also visualizes the distinct site occupancy of Dy at the Ti columns in the grain-boundary region in contrast to the Dy occupation at the Ca columns in the bulk grains, directly showing that Dy is a donor in the bulk and simultaneously an acceptor in the grain-boundary region. In addition to providing an efficient way of tuning the electrostatic potential barriers, this bifunctional effect of Dy emphasizes the significance of understanding the correlation between the atomic-level site occupancy of dopants and the overall electrical properties.

      PubDate: 2017-06-15T06:51:29Z
  • The structural analysis of MWCNT-SiO2 and electrical properties on device
    • Abstract: Publication date: September 2017
      Source:Current Applied Physics, Volume 17, Issue 9
      Author(s): Adem Kocyigit, Ikram Orak, İbrahim Karteri, Serhan Uruş
      Al/MWCNT-SiO2/p-Si device were obtained using chemical techniques and characterized using the I-V (under dark and light conditions) and C-V measurements depending on various frequency. MWCNT-SiO2 composite layer of the device were also characterized using XRD, FTIR, SEM, TEM and TGA measurements. These all results indicated that the MWCNT-SiO2 layer synthesized successfully on Si wafer as a composite form with chemical processes and spin coating. I-V measurements showed that device has good rectifying properties, small saturation current and good photodiode properties. Solar cell conversion efficiency ( η p ) and fill factor (FF) values of the device also were calculated as 0.12% and 47.6%, respectively. It could be seen from C-V measurements that capacitance and conductance properties of the device strongly depended on frequency and voltage. It may be used and improved this device as rectifier, photodiode and capacitor in the future.

      PubDate: 2017-06-15T06:51:29Z
  • Comparison of theoretical and experimental results for band-gap-graded
           CZTSSe solar cell
    • Abstract: Publication date: Available online 13 June 2017
      Source:Current Applied Physics
      Author(s): Mehran Minbashi, Mir Kazem Omrani, Nafiseh Memarian, Dae-Hwan Kim
      The simulation of CZTSSe solar cells is presented in this paper. The simulation results are in reasonable agreement with the experimental data, indicating the reliability of simulation results. New structure is proposed to increase the functionality of the cell. Improved functional performances are achieved by inserting a P-Silicon (P-Si) layer as back surface field. Simulation results suggest that by inserting this P-Si layer, efficiency of the CZTSSe solar cell increases from 12.6% to 16.59%, which is a significant improvement. For the champion cell JSC = 36.27 mA/cm2, VOC = 0.625 V and FF = 73.11% has been achieved.

      PubDate: 2017-06-15T06:51:29Z
  • Enhanced efficiency and stability of polymer solar cells using
           solution-processed nickel oxide as hole transport material
    • Abstract: Publication date: Available online 12 June 2017
      Source:Current Applied Physics
      Author(s): Shanmugam Parthiban, Seungmin Kim, Vellaiappillai Tamilavan, Jihoon Lee, Insoo Shin, D. Yuvaraj, Yun Kyung Jung, Myung Ho Hyun, Jung Hyun Jeong, Sung Heum Park
      Solution-processed nickel oxide (s-NiOx) was synthesized for use as hole-transport layers (HTLs) in the fabrication of polymer solar cell (PSC) devices. The s-NiOx thin-films were deposited using spin-coating and post-annealed at 300 °C, 400 °C, or 500 °C. With increased annealing temperature, the nickel acetate precursor decomposes more fully and forms s-NiOx films that show larger crystalline grain sizes with lower root mean square surface roughness. Bulk heterojunction solar cells fabricated with the new random polymer RP(BDT-PDBT) and [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) using s-NiOx as HTLs exhibit a 4.46% enhancement in power conversion efficiency and better stability compared to conventional PSCs using poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) as HTLs. We believe that the solution-processable and highly stable s-NiOx could be a potential alternative for functional interface materials in optoelectronic devices.

      PubDate: 2017-06-15T06:51:29Z
  • Effect of substrate temperature during the three-stage process on the
           CuInSe2 solar cell characteristics
    • Abstract: Publication date: September 2017
      Source:Current Applied Physics, Volume 17, Issue 9
      Author(s): Muhammad Saifullah, Jihye Gwak, Joo Hyung Park, Seungkyu Ahn, Kihwan Kim, Young Joo Eo, Jae Ho Yun
      CuInSe2 (CISe) with a bandgap of 1.0 eV is the appropriate bottom layer material for the multi-junction solar cell. CISe thin films have been prepared using the three-stage process, in which the substrate temperature (Ts) of the second and the third stage was varied from 490 to 580 °C. The preferred orientation of the CISe film changed from (112) to (220) as the Ts was increased from 490 °C to onward. CISe films had large and columnar grains at all values of Ts, but surface became increasingly smoother as the Ts was increased from 490 to 580 °C. Secondary ion mass spectrometry analysis revealed that Cd diffusion from CdS buffer layer to CISe layer was more when the preferred orientation was (220), which helped in the formation of homojunction inside CISe. Open circuit voltage increased upon increasing the Ts due to the increase in the Na concentration inside CISe. The conversion efficiency of the solar cells increased from 8.80 to 12.64% when the Ts was raised from 490 to 580 °C.
      Graphical abstract image

      PubDate: 2017-06-10T06:47:32Z
  • A study of energy transfer phenomenon leading to photon up-conversion in
    • Abstract: Publication date: Available online 8 June 2017
      Source:Current Applied Physics
      Author(s): Nikifor Rakov, Glauco S. Maciel
      When Ho3+:Yb3+:CaF2 crystalline powders prepared by combustion synthesis were exposed to near-infrared (λ ∼ 975 nm) radiation, intense photon up-conversion (UC) was observed at the visible with emission bands peaked at ∼ 545, ∼650 and ∼750 nm identified as 4f-4f transitions from higher levels (5F4, 5S2) and 5F5 to lower levels 5I8 and 5I7 of Ho3+. The emission bands at the green and red, in particular, have been demonstrated to be useful for temperature sensing based on luminescence intensity ratio technique. However, no model is available in literature to explain the change of the electronic populations of states (5F4, 5S2) and 5F5 with temperature. The UC phenomenon was studied from both theoretical and experimental points of view. A rate equation model with temperature dependent parameters for Ho3+ and Yb3+ electronic populations considering a high sensitization of Ho3+ ions by Yb3+ ions was used. High Yb3+ → Ho3+ energy transfer efficiency was found (∼88% at room temperature). The change with temperature predicted by the model for the luminescence intensity ratio of the UC green and red emission lines agrees well with the experimental data.
      Graphical abstract image

      PubDate: 2017-06-10T06:47:32Z
  • Calcium nitrate (Ca(NO3)2)-based inorganic salt electrode for
           supercapacitor with long-cycle life performance
    • Abstract: Publication date: September 2017
      Source:Current Applied Physics, Volume 17, Issue 9
      Author(s): Sangeun Cho, Jaeseok Han, Jongmin Kim, Yongcheol Jo, Hyeonseok Woo, Seongwoo Lee, Abu Talha Aqueel Ahmed, Harish C. Chavan, S.M. Pawar, Jayavant L. Gunjakar, Jungwon Kwak, Youngsin Park, Akbar I. Inamdar, Hyunjeong Kim, Hyungsang Kim, Hyunsik Im
      A novel water-soluble inorganic Ca(NO3)2 salt electrode is investigated for its pseudocapacitance in an aqueous KOH electrolyte. Commercially available Ca(NO3)2 salt is directly used as the key electrode material. The supercapacitor electrode contains Ca(NO3)2 salt, carbon black, and polyvinylidene fluoride (PVDF) in a ratio of 80:10:10. The Ca(NO3)2-based electrode demonstrates an exceptionally long life cycling stability, and a reasonably sound specific capacitance of 234 F/g is obtained at a current density of 3 A/g. Via chemical and electrochemical reactions, the in-situ activation of the Ca(NO3)2 forms an intermediate CaO which contributes to the pseudocapacitance of the electrode. The electrode undergoes a reversible redox reaction between Cu2+ ↔ Cu+ during the charge-discharge process. Superior rate capability and excellent specific capacitance retention of ∼120% over 2000 cycles are achieved compared with other inorganic salt electrodes.

      PubDate: 2017-06-05T06:44:47Z
  • Synthesis and characterization of novel Cu2O/PVDF nanocomposites for
           flexible ferroelectric organic electronic memory devices
    • Abstract: Publication date: September 2017
      Source:Current Applied Physics, Volume 17, Issue 9
      Author(s): Farag S. Al-Hazmi, Dago M. de Leeuw, A.A. Al-Ghamdi, F.S. Shokr
      Copper oxide nanoparticles loaded Poly(vinylidene fluoride) (PVDF) nanocomposites, at concentrations from 1 to 9 wt%, were developed by casting technique. The effect of the Cu2O nanoparticles on the structure, thermal, mechanical and dielectric properties of the PVDF were inspected. The scanning electron microscopy (FE-SEM) revealed the well dispersion of the Cu2O nanoparticles into the PVDF matrix up to 5 wt%. The X-ray diffraction (XRD) patterns and the infrared spectroscopy (FTIR) measurements implied that the inclusion of the Cu2O nanoparticles into the PVDF matrix leads to a transform of the non-polar semi-crystalline α-phase of the neat PVDF to highly crystallized polar β-phase. Moreover, an increase of the thermal stability and crystallinity of the PVDF after the incorporation of the Cu2O nanoparticles was achieved. The Cu2O/PVDF nanocomposites exhibited excellent cyclic mechanical property compared to the neat PVDF. The introduction of 5 wt% Cu2O nanoparticles into the PVDF composites resulted in remarkable increase of the dielectric constant by 13 times while the dielectric loss was very low. A device based on Al/5 wt% Cu2O doped PVDF/Pt structure is developed. This device shows ferroelectric hysteresis with butterfly like shape and exhibited remanent polarization of 11.2 μC/cm2 with coercive field of 49 MV/m. These superior properties enable the developed Cu2O/PVDF nanocomposite films to be a potential candidate in the field of ferroelectric organic electronic memory devices.
      Graphical abstract image

      PubDate: 2017-05-31T06:39:16Z
  • Relationship between ferromagnetism and, structure and morphology in
           un-doped ZnO and Fe-doped ZnO powders prepared by hydrothermal route
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): V. Mihalache, M. Cernea, I. Pasuk
      The magnetic properties, in the 5 K–350 K temperature range, were investigated in relationship with the structure and morphology of Zn1−xFexO (x = 0, 0.01, 0.03) powders prepared by hydrothermal route. The magnetization measurements reveal that all powders are ferromagnetic at room temperature, with Curie temperature T c , higher than 350 K. The coercivity Hc takes values between 58 Oe and 107 Oe at 300 K and, between 217 Oe and 613 Oe at 5 K. The weak magnetization of the un-doped ZnO powder is temperature independent and was associated with the high surface to volume ratio of the powder particles (or the number of surface defects). The saturation magnetization M s was substantially enhanced (up to a factor of about 20 at 300 K and of about 200 at 5 K) at all temperatures as Fe concentration increased, in spite of reduction of the surface to volume ratio of the powder particles. The Hc vs. T and FC/ZFC curves for the un-doped ZnO show typical ferromagnetic behavior, whereas for the Fe doped powders exhibit Ruderman–Kittel–Kasuya–Yosida (RKKY) - like and spin-glass-like behavior. The observed magnetic phenomena in Fe doped ZnO can be explained on the basis of “donor defects concentration – magnetic cations concentration” phase diagram for dilute magnetic semiconductors.

      PubDate: 2017-05-26T06:28:20Z
  • Ag-nanowires-doped graphene/Si Schottky-junction solar cells encapsulated
           with another graphene layer
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): Jong Min Kim, Sang Woo Seo, Dong Hee Shin, Ha Seung Lee, Ju Hwan Kim, Chan Wook Jang, Sung Kim, Suk-Ho Choi
      Graphene/silver nanowires (Ag NWs)-doped graphene stacks are employed for Si Schottky-junction solar cells as transparent conductive electrodes (TCEs). The doping of graphene by Ag NWs decreases the series resistance of the solar cells and enhances the electrical conductivity of the graphene TCEs, resulting in remarkable improvements of the diode properties of the solar cells. In addition, the Ag NWs on the graphene reduces the reflectance of the solar cells as well as the transmittance of the graphene TCEs. This trade-off correlation makes the power-conversion efficiency maximized to 3.51% at concentration of Ag NWs (nA) = 0.1 wt%. The long-term stabilities of the photovoltaic properties are greatly improved by the encapsulation of the Ag NWs/graphene TCEs with another graphene because of the excellence of graphene as a gas-barrier. These and other nA-dependent behaviors of Raman spectra, work function, sheet resistance, external quantum efficiency, and DC conductivity/optical conductivity ratio are discussed to explain the photovoltaic properties of the solar cells.

      PubDate: 2017-05-26T06:28:20Z
  • First-principal calculations of electronic and optical properties of
           Fe1−xZnxS2 and Zn1−xMgxO alloys
    • Abstract: Publication date: Available online 19 May 2017
      Source:Current Applied Physics
      Author(s): N. Ouarab, M. Boumaour
      Electronic properties of Fe1−xZnxS2 and Zn1−xMgxO alloys are performed by using full potential linearized augmented plane wave method (FP-LAPW). Band gap energies have been calculated by using concomitantly the LDA with Tran Blaha modified Becke-Johnson (TB-mBJ) potentials. The corrected positions related to valence band maximum (VBM) and conduction band minimum (CBM) have been evaluated by many-body perturbation theory in the GW approximation. The electron affinities of these alloys are determined by knowledge the exact position of CBM from the fit of total density of states (TDOS). In the case of 0 at % of (Zn, Mg) alloyed element, pyrite FeS2 and wurtzite ZnO, respectively, exhibit positive electron affinities of 3.34 eV and 4.34 eV, which are in close with experimental measurements. As for optical properties, the absorption coefficient spectra and refraction index variations are performed from momentum matrix elements and interpreted via the projected density of states. The studied alloys show significant responses in visible range and a blue shift in connection with increasing the alloyed element.

      PubDate: 2017-05-20T21:06:30Z
  • Optical polarization in mono and bilayer MoS2
    • Abstract: Publication date: Available online 19 May 2017
      Source:Current Applied Physics
      Author(s): Youngsin Park, Nannan Li, Christopher C.S. Chan, Benjamin P.L. Reid, Robert A. Taylor, Hyunsik Im
      Optical anisotropy in monolayer- and bilayer-MoS2 was investigated by polarization resolved photoluminescence measurements. The photoluminescence of monolayer-MoS2 is found to be partially polarized at 4.2 K and maintains this polarization characteristic up to room temperature, while the photoluminescence of bilayer-MoS2 shows no obvious polarization. This polarization anisotropy is due to strain effects at the interface between the MoS2 layer and the SiO2 substrate, causing symmetry breaking of the MoS2 charge distribution. Calculations using density functional theory of the electron density distribution of the monolayer- and bilayer-MoS2 in the in-plane direction are also presented, giving support to our qualitative analysis.

      PubDate: 2017-05-20T21:06:30Z
  • Mixing sequence driven controlled dispersion of graphene oxide in PC/PMMA
           blend nanocomposite and its effect on thermo-mechanical properties
    • Abstract: Publication date: Available online 17 May 2017
      Source:Current Applied Physics
      Author(s): Santosh Kr. Tiwari, Goutam Hatui, Ramesh Oraon, Amrita De Adhikari, Ganesh Chandra Nayak
      Herein, we report an efficient approach for the fabrication of polymer blend nanocomposites with well-dispersed graphene oxide in polycarbonate (PC)/poly methyl methacrylate (PMMA) through melt compounding under the controlled temperature and pressure. Graphene oxide was synthesized by Improved Hummer's method and consequently dispersed in PC and PMMA through different mixing sequences to access their dispersion in the blend nanocomposites. Thermo-mechanical investigations indicate ∼119.4% increase in tensile strength, ∼64.87% increase in the Young's modulus and ∼16.3% increase in glass transition value for the sample prepared by mixing GO first with PMMA and then with PC, in comparison to neat blend. This reinforcement in thermo-mechanical properties of sample prepared by mixing GO first with PMMA and then with PC, on incorporation of 1% of graphene oxide (by weight) is due to the effective interfacial adhesion and uniform load transfer at the interfaces of polymer blend nanocomposites. Furthermore, Thermogravimetric analysis showed a remarkable decrease in weight loss at elevated temperature for the nanocomposites, which confirms the role of graphene oxide on thermal stability of PNCs. The fabricated blend nanocomposites are ecofriendly, cost effective and can be used for various industrial applications where elevated temperature is required.
      Graphical abstract image

      PubDate: 2017-05-20T21:06:30Z
  • Comparison of desorption enhancement methods in the low temperature plasma
           ionization mass spectrometry for detecting fatty acids in Drosophila
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): Shin Hye Kim, Hyun Jun Jang, Jeong Hyang Park, Hyoung Jun Lee, Jeongkwon Kim, Yong-Hyeon Yim, Dan Bee Kim, Sohee Yoon
      Mass spectrometry (MS) with low temperature plasma (LTP) as an ionization source is one of the widely used ambient methods in analyzing various bio-chemical samples for their detection, identification, differentiation, etc. While the LTP-MS allows selective analysis of a sample with low-molecular weight without thermal damages, it has difficulties desorbing a target molecule from the sample surface with a low volatility. Hence, for the purpose of enhancing the desorption and ionization efficiencies of the LTP-MS when analyzing the fatty acids, two methods were compared: directly heating the sample surface and increasing the vapor pressure of the fatty acid itself by derivatization. In addition, the fatty acids in Drosophila were directly analyzed with the LTP-MS. As a result, it was found that the LTP-MS detection efficiency was enhanced with the derivatization as much as with the heating condition while there was little synergy in employing both of the heating and derivatization together.

      PubDate: 2017-05-15T20:46:35Z
  • In-situ analysis energy level alignment at solution processed HAT(CN)6/PVK
           (PVK:TAPC) interface via XPS and UPS
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): N.A. Talik, B.K. Yap, C.Y. Tan, T.J. Whitcher
      We present in-depth analysis of an n/p heterojunction that consists of 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT(CN)6) (n-type) and Poly(9-vinylcarbazole) (PVK) (p-type) via X-ray Photoelectron Spectroscopy (XPS) and Ultra-violet Photoelectron Spectroscopy (UPS) measurement. The p-type layer is doped with 2 wt% of 1,1-bis-(4-bis(4-tolyl)-aminophenyl) cyclohexene (TAPC). The energy difference (ΔE) at the hetero-junction, magnitude of band bending (V b ) and the vacuum level shift at the interface is modified when PVK is doped with 2 wt% TAPC. The presence of V b at the HAT(CN)6/PVK (PVK:TAPC) interface makes it easier to reach a ΔE ≈ 0 energy offset in order to facilitate charge generation at the interface. Via a Fowler-Nordheim (FN) tunneling curve, it is found that the electron extraction from PVK to HAT(CN)6 at the interface could occur via the tunneling process. This finding provides new insights into novel solutions for high efficiency tandem OLEDs.
      Graphical abstract image

      PubDate: 2017-05-10T20:20:19Z
  • Hybrid color-conversion layers for white emission from fluorescent blue
           organic light-emitting diodes
    • Abstract: Publication date: Available online 9 May 2017
      Source:Current Applied Physics
      Author(s): Seung-Hwan Lee, Deuk Su Jo, Bong Sung Kim, Dae-Ho Yoon, Heeyeop Chae, Ho-Kyoon Chung, Sung Min Cho
      Hybrid color-conversion layers (CCLs) were developed to convert a blue emission from fluorescent organic light-emitting diodes (OLEDs) to obtain a white emission with a high color rendering index (CRI). The hybrid CCLs were composed of an inorganic phosphor, organic dye, and silicon dioxide (SiO2) scattering nanoparticles. The inorganic phosphors convert a part of blue emission from OLEDs to a green-yellow emission effectively. A part of the green-yellow emission was consecutively converted to a red emission with the organic dye. Using the hybrid CCLs, we obtained a balanced white emission with the highest CRI of 93 and the color temperature of 3500 K. The high CRI white OLED showed the power efficiency of 11 lm/W which was enhanced by 1.9 times from that of the blue fluorescent OLED. We showed that the utilization of the SiO2 nanoparticles did not only enhance the power efficiency but also significantly reduce the white color variation to the viewing angle.
      Graphical abstract image

      PubDate: 2017-05-10T20:20:19Z
  • Ground state opto-electronic and thermoelectric response of cubic XSnO3
           (X = Ba, Sr) compounds
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): M. Bilal Saddique, Muhammad Rashid, Adnan Afzal, Shahid M. Ramay, Farooq Aziz, Asif Mahmood
      The density functional has been implemented to deliberate the cubic perovskite XSnO3 (X = Ba, Sr) for their elastic, electronic, optical as well as thermoelectric characteristic. The XSnO3 (X = Ba, Sr) illustrates good pact of lattice parameter for these iso-structural compounds having cubic perovskite structure. The generalized gradient approximation based on the exchange-correlation functional is applied for computing structural and mechanical characteristic, whereas the electronic, optical and thermoelectric properties have been studied by the functional suggested by Tran and Blaha that is termed as of modified Becke-Johnson (mBJ) functional. The thermodynamics stability is recognized through the expression of enthalpies of formation, which is further verified from the calculated structural properties of cubic perovskite XSnO3 (X = Ba, Sr). Moreover, various elastic parameters such has bulk modules B, Cij, shear modulus G, Young's modulus Y, anisotropy factor, B/G ratio and Poisson's ratio ν have also been reported. It has been observed by band structure computation that the studied compounds exhibit an indirect band gap between the unoccupied Ba/Sr 6s/5s and the occupied O 2p orbitals. Detailed study of optical properties is presented under the incident photon energy upto 28 eV. Our computed static dielectric constant ε 2(0) and refractive index n(0) are comparable with other theoretical and experimental values. Thermoelectric properties are presented in terms of computed Seebeck coefficient, electrical and thermal conductivities and their variation with the rise in temperature suggest that the studied compounds may find applications in the construction of various thermo-electric devices.

      PubDate: 2017-05-05T19:55:19Z
  • Enhanced cycle stability of silicon nanoparticles coated with
           nitrogen-doped carbon layer for lithium-ion battery anode
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): Hun Seok Choi, Su Jae Kim, Hyun Woo Choi, Cheul-Eon Park, Ying Jun Gao, Yang Hang, Se-Young Jeong, Jong-Pil Kim, Jong-Seong Bae, Chae-Ryong Cho
      We prepared single-crystal Si nanoparticles (Si NPs) ∼50 nm in diameter using a laser photopyrolysis technique and formed a nitrogen-doped carbon layer on them using pyrrole and FeCl3 to increase the cycle stability of the Si anodes during volume expansion and contraction. The surface chemical bonding states of the nitrogen-doped carbon-coated Si NPs were investigated. The specific capacity and capacity retention of the sample with 1 g of FeCl3 were the highest at approximately 967.1 mAh g−1 and 87.3% after 300 cycles at 1 C, respectively. The diffusion coefficient of Li ions after 1000 test cycles was 9.64 × 10−8 cm2 s-1. The higher cycling stability of the Si@NC NPs could be attributed to the nitrogen-doped carbon layers, which provided an efficient transport pathway for the electrons.

      PubDate: 2017-05-05T19:55:19Z
  • Significant photoinduced increment of reflectivity coefficient in
    • Abstract: Publication date: Available online 3 May 2017
      Source:Current Applied Physics
      Author(s): M. Chrunik, A. Majchrowski, K. Ozga, M. Ya. Rudysh, I.V. Kityk, A.O. Fedorchuk, V. Yo. Stadnyk, M. Piasecki
      Synthesis of LiNa5Mo9O30 micropowders by means of sol-gel method through the citrate way was carried out. The DFT band structure calculations for obtained powders were done. Following the performed calculations, investigations of various optical functions as well as elastic properties were carried out. Basing on the analysis of the obtained results we performed photoinducing treatment of the samples near and outside the first UV spectral maximum of reflectivity (R) using the radiation of photoinducing UV nanosecond laser at 337 nm and second harmonic generated 532 nm signal originating from Nd:YAG laser emitting 1064 nm radiation, respectively. Significant enhancement of relative reflectivity (ΔR/R) in the spectral range 335–413 nm (3.7–3.0 eV) caused by photoinducing UV nanosecond laser treatment at 337 nm was observed. Huge sensitivity to the wavelength of photoinducing radiation of LiNa5Mo9O30 reflectivity was found. Discovered phenomenon indicates the possibility of LiNa5Mo9O30 application as an efficient optical trigger. Additionally it may be of huge importance for the production of high selective sensors of the laser light. Moreover, in a future we can use LiNa5Mo9O30 crystalline powder to make composite by embedding into polymer or glass matrices.
      Graphical abstract image

      PubDate: 2017-05-05T19:55:19Z
  • Glassy carbon electrode modified with poly(methyl orange) as an
           electrochemical platform for the determination of 4-nitrophenol at
           nanomolar levels
    • Abstract: Publication date: Available online 2 May 2017
      Source:Current Applied Physics
      Author(s): Krishnan Giribabu, Yuvaraj Haldorai, Muruganantham Rethinasabapathy, Sung-Chan Jang, Ranganathan Suresh, Wan-Seob Cho, Young-Kyu Han, Changhyun Roh, Yun Suk Huh, Vengidusamy Narayanan
      In this study, poly(methyl orange) (PMO) was synthesized by electrodeposition onto a glassy carbon electrode (GCE), and the resulting structure was examined for the determination of 4-nitrophenol (4-NP). Cyclic voltammetry revealed that the PMO-modified GCE (PMO/GCE) exhibited excellent electrocatalytic activity for the oxidation of 4-NP in a 0.5-M phosphate buffer solution. In contrast, the bare GCE showed no oxidation peak. Interestingly, PMO/GCE exhibited an oxidation peak at approximate 0.93 V, and the background current was higher than that of the bare GCE. Furthermore, the developed electrochemical sensor exhibited a linear relationship with the 4-NP concentration from 600 nM to 10 μM, and the limit of detection was 170 nM (signal/noise = 3). The sensor demonstrated excellent selectivity, good stability, and reproducibility. It was applied to the determination of 4-NP in water samples by the standard addition method and gave recoveries of 99.2–100.9%.

      PubDate: 2017-05-05T19:55:19Z
  • Morphological design of optical cavities for frequency-selective black
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): Da-Som Kim, Jin-Woo Cho, KeumHwan Park, Young-Seok Kim, Sun-Kyung Kim
      We study various morphological effects due to optical cavities that are formed into metal substrates for the implementation of frequency-selective black absorbers. The absorption spectra (λ = 500–3000 nm) of patterned metal substrates are investigated by conducting full-vectorial electromagnetic simulations. The diameter of optical cavities determines a cut-off wavelength at which absorption begins to drop off exponentially. The cut-off wavelength is gradually redshifted by increasing the diameter of the optical cavities, which is associated with the tuning of the fundamental transverse mode. The height of optical cavities determines the number and amplitude of absorption peaks, which originate from Fabry-Perot modes with different longitudinal orders. Also, the absorption features depend strongly on the refractive index of the material within optical cavities; optical cavities filled with a dielectric yield improved absorption, even with a relatively shallow height. With an integration of patterned tantalum (Ta) and tungsten (W) thermal emitters, the power conversion efficiencies of thermophotovoltaics are predicted, accounting a body temperature of 1300 K and the quantum efficiency of a typical infrared photovoltaic cell. Tailored optical cavities lead to a dramatic enhancement in the power conversion efficiency up to 11.6 and 2.1 fold compared to planar structures, for Ta and W thermal emitters, respectively. These numerical findings and underlying physics will provide valuable design strategies to thermal radiation engineered applications such as solar absorbers, radiative coolers, as well as thermophotovoltaics.

      PubDate: 2017-04-29T19:40:29Z
  • Fe-based multifunctional nanoparticles with various physicochemical
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): Junyoung Kwon, Xiang Mao, Jaebeom Lee
      Over the past few decades, many studies have assessed Fe-based nanoparticles because of their high earth abundance, inexpensive precursors, unique optical properties, electromagnetic nature, biocompatibility, and interactivity with cells. By controlling the composition of a composite, the morphology, size, physical properties, and related functionalities, the synthesized nanomaterials can be altered for specific applications. This review introduces several methods for synthesizing iron-based binary/ternary chalcogenides, iron-based bimetallic materials, and iron-based magnetoplasmonic materials with a range of properties. Furthermore, assembled nanostructures make it possible for us to use these building blocks for broader and customized applications depending on their controlled arrangement. This will facilitate the potential application of iron-based functional materials in spintronics, biomedicine, electronics, and catalysis.
      Graphical abstract image

      PubDate: 2017-04-29T19:40:29Z
  • High alcohol-soluble MoOx gel for interfacial layer in organic solar cells
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): Jian Xiong, Zhen He, Shiping Zhan, Bingchu Yang, Xiaowen Zhang, Ping Cai, Cong Xu, Xiaogang Xue, Jian Zhang
      Water-free solvent soluble, low-temperature processed metal oxides are important for preparing efficient and stable electronic devices, as well as the convenience in simplifying the device production process. Here we reported a facile approach with the features of low-temperature and solution-based process for the formation of a MoOx (s-MoOx) film as interface layer in polymer solar cells (PSCs). The absorbability, elementary composition, electronic property and surface microstructure of the s-MoOx are investigated in detail by ultraviolet–visible spectrophotometer (UV–vis), X-ray photoelectron spectrometry (XPS), ultraviolet photo-electron spectrometer (UPS) and atomic force microscopy (AFM). These investigations confirmed that such MoOx xerogel has high solubility in the organic alcohol solvents, such as ethanol and methanol. Meanwhile, this s-MoOx can be applied as the interfacial layer in organic solar cells via a low-temperature treatment (about 100 °C) due to its proper physical properties, and a power conversion efficiency (PCE) over 3% was achieved. In addition, the devices with s-MoOx shows excellent air-stability, and the PCE efficiency can maintain about 84% of its initial value after 100 h exposure in air, which is dramatically enhanced comparing with the common devices with PEDOT:PSS layer.

      PubDate: 2017-04-29T19:40:29Z
  • Calculated structural and electronic interactions of the nano dye molecule
           Ru(4,4´−COOH−2,2´−bpy)2(NCS)2(N3) with a iodide/triiodide redox
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): E. Shomali, I. Abdolhosseini Sarsari, S. Javad Hashemifar, M. Alaei
      In this paper, dye sensitized solar cell based on nano dye molecule N3 are investigated by using density functional computations. The main focus is on the N3 dye molecule and corresponding complexes formed at the interface between electrolyte and dye, during the regeneration process. The optimized geometry and electronic structure of the molecule and complexes are calculated by using the pseudo-potential as well as full-potential techniques. The absorption spectra of metalliferous dye molecule, N3, and its complexes are computed in the framework of time dependent density functional theory. We determine the reaction path of dye regeneration by Nudged Elastic Band (NEB) method. IR spectrum of the N3 dye molecule were also calculated. We found that complexes of N3 dye molecule and transition states formed in reactions, are magnetic.

      PubDate: 2017-04-29T19:40:29Z
  • The study of electronic, magnetic, magneto-optical and thermoelectric
           properties of XCr2O4 (X = Zn, Cd) through modified Becke and Johnson
           potential scheme (mBJ)
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): Shahid M. Ramay, M. Hassan, Q. Mahmood, Asif Mahmood
      The electronic structure is analyzed to elucidate the magnetic and optical characters and the thermoelectric response of XCr2O4 (X = Zn, Cd) stabilized in the cubic phase by using DFT based FP-LAPW method. The modified Becke–Johnson (mBJ) functional is utilized to compute precise band structures (BS) and density of states (DOS), which confirm ferromagnetic semiconducting behavior. The origin of ferromagnetism explored by computing crystal field energy ( Δ C F ) , John-Teller energy ( Δ J T ) and exchange splitting energies Δ E X ( d ) and Δ E X ( p d ) . It is found that strong hybridization results in decay in Cr the magnetic moment and creates the magnetic moments at the nonmagnetic sites. The optical parameters reveal the suitability for energy harvesting devices. Finally, the BoltzTraP code has been implemented to study the thermoelectric properties, which show that increase in temperature increases the electrical conductivity, thermal conductivity and the power factor, while Seebeck coefficient reduces. Hence, the studied compounds are also suitable for thermoelectric devices to realize useful alternative energy sources.

      PubDate: 2017-04-29T19:40:29Z
  • Significant enhancement of resonance magnetoelectric coupling in
           miniaturized lead-free NiFe2O4–BaTiO3 multilayers
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): Deepak Rajaram Patil, Yi Sheng Chai, June-Hee Kim, Joong-Hee Nam, Jeong-Ho Cho, Byung-Ik Kim, Kee Hoon Kim
      With increasing demands toward device miniaturization, Pb-free magnetoelectric laminates (MELs) with a small lateral dimension of ∼3 × 3 mm2 have been synthesized by the tape-casting method. The MELs are composed of alternating layers of magnetostrictive NiFe2O4 and piezoelectric BaTiO3 with a uniform single layer thickness of t = 50 and 15 μm, respectively. Both laminates exhibit much larger longitudinal ME voltage coefficient α E33 than the transverse ME voltage coefficient α E31 at both off-resonant and resonant frequencies, which is attributed to the preferential easy-plane alignment of the magnetic moments. Furthermore, enhancement in α E33 by more than 5 times has been achieved upon decreasing t from 50 to 15 μm in both resonance and off-resonance conditions. The enhanced α E33 values indicate that nearly ideal interface coupling between the ferromagnetic and piezoelectric layers is realized in the miniaturized, thinner MEL, pointing to practical application potential towards developing mass-produced, low-cost ME devices.

      PubDate: 2017-04-29T19:40:29Z
  • The preparation, performance and lithiation mechanism of cobalt-doped zinc
           oxide as a high performance anode material for LIB
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): Yue Li, WanWan Li, Minhua Fang, XiaoLin Yao, Chao Chen, Miao Shui, Jie Shu, Yuanlong Ren
      Zn1-x Co x O (0 ≤ x ≤ 0.15) anode material was prepared by an easy polyacrylamide assisted sol-gel route. The successful replacement of Zinc by Cobalt within Cobalt content x ≤ 0.09 was confirmed by structural characterization. The introduction of Cobalt element greatly improved the electro-chemical performances of the matrix Zinc oxide. Without carbon coating, at the 20th cycle, Zn0.91Co0.09O anode still preserved a capacity a little bit more than 1000  mA h g−1 and a capacity more than 600  mA h g−1 was retained at the end of the 50th cycle. Better rate capability was also witnessed. The SEM, EIS at OCV, CV and in situ XRD were further carried out to elucidate the lithiation mechanism. The role Cobalt doping played can be summarized as follows: the stabilization of the Li2Zn phase, the minimization of charge transfer resistance and the enhanced reversibility of the reduction from metal oxide to metal.
      Graphical abstract image

      PubDate: 2017-04-29T19:40:29Z
  • High photocatalytic efficiency and stability of chromium-indium codoped
           ZnO thin films under sunlight irradiation for water purification
           development purposes
    • Abstract: Publication date: August 2017
      Source:Current Applied Physics, Volume 17, Issue 8
      Author(s): Refka Mimouni, Adel Souissi, Ali Madouri, Karem Boubaker, Mosbah Amlouk
      In this work, we aimed an effective low-cost system for water purification from Methylene Blue using the photocatalytic performance of (Cr,In) codoped ZnO sprayed thin films under sunlight irradiation. XRD analysis demonstrate that the samples crystallized in würtzite ZnO phase, with a privileged orientation of crystallites towards (002) direction parallel to c-axis. The obtained images of AFM and SEM micrographs showed the enhancement of the roughness of ZnO films by codoping. In addition, the optical investigations indicated that the band gap values of (Cr,In) codoped ZnO thin films decreases from 3.3 eV to 3.1 eV in terms of (Cr, In) contents, whence, more solar energy can be exploited for photocatalytic reactions. Likewise, from PL study, the decrease of UV intensity peak by codoping points out the recombination inhibition in ZnO thin films. Also, the presence of defects demonstrated by visible emission has an important role in photocatalysis because on the surface of defects, surface redox reactions are taking place. So, they act as active sites of (Cr,In) codoped ZnO photocatalyst. Moreover, the effect of hydroxide OH radicals and the superoxide anion radicals (O2 -) in photocatalytic mechanism for Methylene Blue degradation was discussed. Furthermore, (Cr,In) codoped ZnO thin films showed an excellent photodegradation efficiency under sunlight irradiation and present high recycling performance even after three re-use cycles.
      Graphical abstract image

      PubDate: 2017-04-29T19:40:29Z
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