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  Subjects -> ENGINEERING (Total: 2267 journals)
    - CHEMICAL ENGINEERING (190 journals)
    - CIVIL ENGINEERING (183 journals)
    - ELECTRICAL ENGINEERING (99 journals)
    - ENGINEERING (1196 journals)
    - ENGINEERING MECHANICS AND MATERIALS (391 journals)
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ENGINEERING (1196 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Full-text available via subscription   (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: 216)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 1)
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: 10)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 4)
Advanced Science     Open Access   (Followers: 4)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 5)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 6)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Artificial Neural Systems     Open Access   (Followers: 3)
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: 14)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 9)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 18)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
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: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 35)
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: 28)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access  
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: 5)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 6)
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 Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 4)
Applied Sciences     Open Access   (Followers: 3)
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: 8)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 2)
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: 7)
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: 7)
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: 3)
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: 3)
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: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 1)
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     Full-text available via subscription   (Followers: 13)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 40)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 4)
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: 4)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 4)
Coatings     Open Access   (Followers: 2)
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: 23)
Composite Interfaces     Hybrid Journal   (Followers: 5)
Composite Structures     Hybrid Journal   (Followers: 252)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 176)
Composites Part B : Engineering     Hybrid Journal   (Followers: 224)
Composites Science and Technology     Hybrid Journal   (Followers: 164)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 12)
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: 25)
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: 8)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 25)
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: 7)
Control Engineering Practice     Hybrid Journal   (Followers: 40)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 24)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)

        1 2 3 4 5 6 | Last

Journal Cover Current Applied Physics
  [SJR: 0.716]   [H-I: 55]   [4 followers]  Follow
    
   Full-text available via subscription Subscription journal  (Not entitled to full-text)
   ISSN (Print) 1567-1739
   Published by Elsevier Homepage  [3032 journals]
  • Electronic structure and quantum transport properties of boron and
           nitrogen substituted graphene monolayers
    • Abstract: Publication date: July 2017
      Source:Current Applied Physics, Volume 17, Issue 7
      Author(s): Puspitapallab Chaudhuri, Angsula Ghosh, M.S. Gusmão, C. Mota, H.O. Frota
      In this work we use ab initio density functional theory (DFT) and propose three new configurations of substituted graphene monolayers where the carbon atoms are replaced selectively by boron and nitrogen. The stable equilibrium geometries and corresponding structural, electronic and transport properties of the resulting graphene-like BC, NC and BN hexagonal single-atomic-layer compounds are determined. The characteristics of the NC and BC new compounds are found to be metallic. Our proposed boron-nitrogen hexagonal structure behaves as a semiconductor with gap of 0.52 eV, while the h-BN (alternating boron and nitrogen in graphene structure) studied so far widely is typically an insulator or a wide-band semiconductor. The value of electric current in BC structure is found to be higher than that in usual graphene for a given value of the bias voltage.

      PubDate: 2017-04-22T19:27:43Z
       
  • Improved exciton dissociation and charge transport in energetically
           cascaded trilayer organic solar cells
    • Abstract: Publication date: July 2017
      Source:Current Applied Physics, Volume 17, Issue 7
      Author(s): Ji-Won Seo, Sang-Hoon Lee, Jung-Yong Lee
      We demonstrate improved exciton dissociation and charge transport in trilayer organic solar cells (OSCs). The interlayer with an intermediate energy level between the main donor and acceptor levels assists the dissociation of excitons in the charge transfer state (CT) and aids the charge transport by increasing a CT state energy. Additionally, the total absorption of the OSC was increased due to the complementary absorption of the inserted interlayer. Experimentally, when a chloroaluminum phthalocyanine (ClAlPc) layer was inserted between copper phthalocyanine (CuPc) and C60 in a trilayer OSC, the internal quantum efficiency (IQE) was greatly enhanced by 30% in the wavelength range of 350–550 nm. The enhancement of IQE results in an increase of the power conversion efficiency from 1.30% to 1.69%.

      PubDate: 2017-04-16T06:08:52Z
       
  • Design and analysis of a new composite double negative metamaterial for
           multi-band communication
    • Abstract: Publication date: July 2017
      Source:Current Applied Physics, Volume 17, Issue 7
      Author(s): Mohammad Jakir Hossain, Mohammad Rashed Iqbal Faruque, Mohammad Tariqul Islam
      In this paper, a double C-shaped structure of double negative composite metamaterial is designed and depicts in configurations that can capable in a multi-band microwave frequency band. The design has achieved relative negative permeability, relative negative permittivity and relative negative refractive index. Analysis and comparison were done by using four configurations of composite metamaterial such as horizontal 1 × 1 array and vertical 1 × 1 array structures and the horizontal 1 × 1 and vertical 1 × 1 unit-cell configurations. Multi-band operating frequencies namely, S-band, C-band and X-band have been achieved using all configurations. The proposed metamaterial size is 1.2 cm × 1.2 cm × 0.16 cm which includes all geometrical parameters to fit the design inside the substrate area. Computer Simulation Technology (CST) is adopted to investigate this design where an incident electromagnetic wave travelling along the positive z-axis with an E-field polarized along the y-axis. The results of the proposed metamaterial depict multi-band metamaterial response over the frequency span from 1 to 15 GHz. The effective medium ratio of the metamaterial unit-cell is 7.44. Moreover, the results clearly seen that the single-negative and double-negative metamaterial characteristics of the unit-cell and arrays over the multi-band. The dimensions and scattering parameters of the proposed double C-shaped metamaterial are suitable for the S -band, C-band and X-band applications.

      PubDate: 2017-04-16T06:08:52Z
       
  • Electric-field control of magnetic property in perpendicularly magnetized
           Co0.25Pd0.75/PMN-PT heterostructure
    • Abstract: Publication date: July 2017
      Source:Current Applied Physics, Volume 17, Issue 7
      Author(s): Ji-Wan Kim, Ju-Hyun Kim, Chun-Yeol You, Sung-Chul Shin
      We report about the electric-field control of magnetic properties in a perpendicularly magnetized Co0.25Pd0.75 film deposited on PMN-PT (lead magnesium niobate-lead titanate) substrate. The effective perpendicular anisotropy coefficient K eff is efficiently tuned via the electric field up to 2 MV/m from 2.5 × 104 to 0.8 × 104 J/m3, which leads to the change of the effective magnetic anisotropy field μ 0 Δ H e f f  = −45 mT. With a time-resolved magneto-optical Kerr effect, we observed the precession frequency change Δf = 0.8 GHz. Our simulation estimates that this value corresponds to Δf = −3 GHz and Δf/f = −0.23 in a scheme of ferromagnetic resonance measurement.

      PubDate: 2017-04-16T06:08:52Z
       
  • Discharge source-dependent variation in the densities of active species in
           the flowing afterglows of N2 RF and UHF plasmas
    • Abstract: Publication date: July 2017
      Source:Current Applied Physics, Volume 17, Issue 7
      Author(s): André Ricard, Jean-Philippe Sarrette, Byungwook Jeon, Yu Kwon Kim
      With a potential application to surface modification of oxide materials in mind, active species in RF and microwave (UHF) N2 afterglows were analyzed in our newly designed flowing reactors. For both plasma systems, discharge of N2 was generated in a long quartz tube with a small diameter (dia. 5–6 mm) and then was directly injected into a chamber with a large diameter of 15–20 cm. The discharge condition was set to be similar between the two systems; the gas pressure, flow rate and the applied power were 6 Torr, 0.6 slm and 100 W, respectively. Under this condition, the residence time at the chamber inlet was (1–3) x 10−3 s. The RF and UHF afterglows were formed in the chamber with luminous jets from the end of the discharge tube. However, we found that the densities of active species were quite source-dependent; N and N2(A) densities were higher in UHF than in RF in spite of more O-atoms impurity. The origin of such difference is also attributed to the inherent difference in the nature of excitation between the two plasma sources; RF is more vibrational and is longer than UHF.

      PubDate: 2017-04-16T06:08:52Z
       
  • Exchange couplings calculation in Sr2CrNO6 (N = Os, Ir) Double
           Perovskites: Monte Carlo simulation
    • Abstract: Publication date: July 2017
      Source:Current Applied Physics, Volume 17, Issue 7
      Author(s): O. El Rhazouani, A. Slassi, Y. Ziat, A. Benyoussef
      Exchange couplings in Sr 2 CrNO 6 (N = Os, Ir) Double Perovskites (DPs) have been calculated numerically by using a Monte Carlo Simulation (MCS) in the frame work of Ising model by means of a relation between internal energy per site and magnetization per site. Two model parameters α and α ' have been proposed for Sr 2 CrOsO 6 and Sr 2 CrIrO 6 , respectively. The exchange couplings have been computed by varying α and α ' through a MCS to find their values corresponding to the transition temperature 725K specific to Sr 2 CrOsO 6 and 884 K specific to Sr 2 CrIrO 6 . The exchange couplings J C r − O s = − 35.201 m e V , J C r − C r = 5.452 m e V and J O s − O s = 14.873 m e V have been obtained for Sr 2 CrOsO 6 , while J C r − I r = − 24.464 m e V , J C r − C r ' = 2.181 m e V and J I r − I r = 16.730 m e V have been obtained for Sr 2 CrIrO 6 . Magnetization and magnetic susceptibility have been investigated in both compounds. Internal energy per site has been given.

      PubDate: 2017-04-16T06:08:52Z
       
  • Oxide heterostructure research in Korea
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Woo Seok Choi, Sungkyun Park, Hiroki Taniguchi, Tae Won Noh


      PubDate: 2017-04-09T06:25:18Z
       
  • Evidence for indirect band gap in BaSnO3 using angle-resolved
           photoemission spectroscopy
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Beom Soo Joo, Young Jun Chang, Luca Moreschini, Aaron Bostwick, Eli Rotenberg, Moonsup Han
      Transparent BaSnO3 thin films have been proposed as an alternative transparent conducting oxide (TCO). Although bulk synthesis and high-quality fabrication of epitaxial films are well established, there are still unsolved aspects about their electronic structure, such as the direct or indirect nature and the size of the band gap. We investigated the electronic structure of epitaxial BaSnO3 thin films using in situ angle-resolved photoemission spectroscopy. We directly measured an indirect band gap of 3.7 eV, a value compatible with those of previous reports, but we also identified additional in-gap states at −1.6 eV below the conduction band minimum that we attribute to intrinsic defects, mainly oxygen vacancies.
      Graphical abstract image

      PubDate: 2017-04-09T06:25:18Z
       
  • Ablation laser fluence as an effective parameter to control
           superconductivity in Ba1−xKxBiO3 films
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Hodong Lee, Minu Kim, O.B. Korneta, Shinbuhm Lee, Tae Won Noh
      Potassium doping in insulating BaBiO3 induces superconductivity, with high superconducting transition temperatures, T c, of up to 31 K in bulk. We investigated growth control of superconducting properties of BKBO films, by varying laser fluence using pulsed laser deposition technique. As cation stoichiometry, especially potassium concentration in BKBO films, was sensitively changed with laser fluence, we were able to precisely control T c of BKBO films. Following the trend of the bulk phase diagram, T c showed the highest value of 24.5 ± 0.5 K at the optimal stoichiometry. This result can provide optimal guidance for the synthesis of high-quality BKBO films, and demonstrates the effectiveness of laser fluence to study emerging superconducting phenomena in PLD-grown complex oxide thin films.

      PubDate: 2017-04-09T06:25:18Z
       
  • Growth and engineering of perovskite SrIrO3 thin films
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Abhijit Biswas, Yoon H. Jeong
      5d transition-metal-based oxides display emergent phenomena due to the competition between the relevant energy scales of the correlation, bandwidth, and most importantly, the strong spin-orbit coupling (SOC). Starting from the prediction of novel oxide topological insulators in bilayer ABO3 (B = 5d elements) thin-film grown along the (111) direction, 5d-based perovskites (Pv) form a new paradigm in the thin-film community. Here, we reviewed the scientific accomplishments in Pv-SrIrO3 thin films, a popular candidate material for observing non-trivial topological phenomena. Although the predicted topological phenomena are unknown, the Pv-SrIrO3 thin film shows many emergent properties due to the delicate interplay between its various degrees of freedom. These observations provide new physical insight and encourage further research on the design of new 5d-based heterostructures or superlattices for the observation of the hidden topological quantum phenomena in strong spin-orbit coupled oxides.

      PubDate: 2017-04-09T06:25:18Z
       
  • Investigation of interface magnetism of complex oxide heterostructures
           using polarized neutron reflectivity
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Surendra Singh, S. Basu
      Multilayered structures with artificial oxide hetero-interfaces have recently been dominating the field of new states of matter. The unexpected properties and related functionalities at the interface of complex oxide heterostructures as a consequence of the symmetry breaking, electronic reconstruction etc., make these complex oxide interfaces particularly challenging for understanding the fundamental mechanism and interaction across the interfaces. Magnetic modulation, novel magnetic coupling and emerging interface induced magnetization at the interfaces of complex oxide heterostructures have made the search for their technological applications as an intense field of research in recent time. However to study the structure and magnetism in such interfaces require tools with interface specificity. Polarized neutron reflectivity is a non-destructive technique which has played a decisive role in investigation of interfacial magnetic structures and in understanding the underlying physics in this rapidly developing field. This article presents a review of some recent experimental results on emerging magnetization at the interfaces of complex oxide heterostructures specifically investigated using polarized neutron reflectivity.

      PubDate: 2017-04-09T06:25:18Z
       
  • Tailoring two-dimensional electron gas conductivity at oxide
           heterointerfaces
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Taemin Ludvic Kim, Ho Won Jang
      Recently, advances in creating complex oxide heterostructures in atomic scale and research on special properties appears at the interfaces between two different transition-metal oxides, have promoted a new era of materials and physics research. At the heterointerface, unexpected properties could be detected which does not exist in the bulk. Two-dimensional electron gas (2DEG) at the oxide heterointerface between two insulating dielectric perovskite oxides, LaAlO3 and SrTiO3, has attracted tremendous attention with the metallic conductivity at the interface since its discovery in 2004. Intensive experimental and theoretical studies have showed that 2DEG at the oxide heterointerface exhibits a vast diversity of novel properties including superconductivity, ferromagnetism, and field induced metal-insulator phase transitions. In this review, the origin and important factors of 2DEG at the oxide heterointerface and the way to manipulate this interfacial system will be discussed.

      PubDate: 2017-04-09T06:25:18Z
       
  • Atomic-scale visualization of initial growth of perovskites on SrTiO3(001)
           using scanning tunneling microscope
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Young Jun Chang, Soo-hyon Phark
      The growth of perovskite oxide films is known to be strongly influenced by both substrate surface lattice symmetry and stoichiometry. However, this has been postulated mainly based on indirect evidences. Scanning tunneling microscopy (STM) is unambiguously capable of identifying the real-space distribution of the structural and electronic properties of solid surfaces. Therefore, oxide film growth technologies combined with STM are strongly desirable for resolving atomic-scale growth mechanisms of perovskite thin films. Here, we review recent advances in STM studies on initial growth stages of perovskite oxides on SrTiO3(001). First, we introduce surface terminations and reconstructions of SrTiO3(001), as well as their influence on the initial growth of perovskite films studied by STM on an atomic-scale, followed by a discussion of a feasible model for the surface atomic structures and chemistries behind such growth behaviors. We then introduce studies on the growth dynamics of perovskite oxides on SrTiO3(001) in terms of temperature (T) and thickness-resolved STM: (1) Layer-by-layer identification of T-dependent surface structures of ultrathin SrRuO3, suggesting a dramatic change in the surface migration barrier caused by switching of the surface terminations and (2) a prototypical study on the surface diffusion dynamics in perovskite growth realized by the application of the classical diffusion model to the island nucleation stage of SrTiO3 homoepitaxy.
      Graphical abstract image

      PubDate: 2017-04-09T06:25:18Z
       
  • Surface morphology and dielectric behavior of perovskite SrTiO3 thin film
           in heterostructure electroluminescence devices
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Hiroshi Takashima, Myunghee Cho, Tomoyasu Taniyama, Mitsuru Itoh
      Epitaxial SrTiO3 thin film was grown on 1%-Nb-doped SrTiO3 (001) substrate by pulsed laser deposition (PLD). Post-annealing at 1050 °C drastically changes the particle-type surface morphology of the as-grown film to a well-defined step-terrace structure. An atomically smooth surface was obtained with a step height of about 0.4 nm, which corresponds to one-unit-cell of SrTiO3 (a = 0.3905 nm). The dielectric constants ε r at 300 and 2 K were found to be 120 and 520 at 100 kHz, respectively. The dielectric losses at 300 and 2 K were 2.0 × 10−5 and 1.2 × 10−5 at 100 kHz, respectively. Temperature dependence of the dielectric properties showed suppressed quantum paraelectricity. Post-annealed films with an atomically smooth surface used as an insulating layer contribute to the high performance of thin-film electroluminescent (TFEL) heterostructure devices. Preparation of ideal interfaces of different materials may aid in the development of heterostructure electronic devices.

      PubDate: 2017-04-09T06:25:18Z
       
  • Non-piezoelectric effects in piezoresponse force microscopy
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Daehee Seol, Bora Kim, Yunseok Kim
      Piezoresponse force microscopy (PFM) has been used extensively for exploring nanoscale ferro/piezoelectric phenomena over the past two decades. The imaging mechanism of PFM is based on the detection of the electromechanical (EM) response induced by the inverse piezoelectric effect through the cantilever dynamics of an atomic force microscopy. However, several non-piezoelectric effects can induce additional contributions to the EM response, which often lead to a misinterpretation of the measured PFM response. This review aims to summarize the non-piezoelectric origins of the EM response that impair the interpretation of PFM measurements. We primarily discuss two major non-piezoelectric origins, namely, the electrostatic effect and electrochemical strain. Several approaches for differentiating the ferroelectric contribution from the EM response are also discussed. The review suggests a fundamental guideline for the proper utilization of the PFM technique, as well as for achieving a reasonable interpretation of observed PFM responses.

      PubDate: 2017-04-09T06:25:18Z
       
  • Magnetoelectricity in Fe/PbTiO3/Fe superlattices
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Jaekwang Lee
      Using the first-principles density functional calculations, we have investigated the magnetoelectric coupling at the Fe/PbTiO3/Fe superlattices by varying the number of ferroelectric PbTiO3 layers. We find that the change of Fe magnetization is electrically tunable, almost linear in the depolarizing field, and occurs very near the superlattice interface region. The maximal magnetoelectric coupling constant in the Fe/PbTiO3/Fe superlattices is estimated to be about 4 × 10−10 G cm2/V, which is quite similar order of magnitude as that recently experimentally achieved in Co (7 nm)/Pb(Zr,Ti)O3.

      PubDate: 2017-04-09T06:25:18Z
       
  • Ferroelectric BiFeO3/TiO2 nanotube heterostructures for enhanced
           photoelectrochemical performance
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Heejin Lee, Ho-yong Joo, Chulmin Yoon, Joonbong Lee, Hojin Lee, Jinsik Choi, Baeho Park, Taekjib Choi
      Ferroelectric based heterostructures have shown great promises in solar water splitting due to unique photoelectrochemical (PEC) properties including polarization-induced charge separation and tunable electrochemical surface reaction. A highly ordered ferroelectric BiFeO3/TiO2 nanotube (TNT) heterostructures were fabricated by anodic oxidation and pulsed laser deposition. The microscopic morphology, optical, and PEC properties of nanostructures were characterized. The BiFeO3/TNT photoelectrode is photoactive under visible light illumination, which exhibits higher photocurrent from greater water oxidation, compared with the pure TNT photoelectrode. The coating thickness of BiFeO3 strongly affected the photoelectrochemical properties. The enhanced PEC performance could be attributed to the effective charge separation and the favorable band bending for water oxidation, originating from ferroelectric polarization-related internal field.

      PubDate: 2017-04-09T06:25:18Z
       
  • Effect of substrate orientation on ferroelectric behavior of monoclinic
           BiFeO3 thin film
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): B.C. Jeon, S.M. Yang, S.C. Chae
      We report on ferroelectric properties of the monoclinic BiFeO3 thin films grown on (001) and (110) SrTiO3 substrates. Structural analysis using X-ray diffractometer and the electrical characterization of ferroelectricity reveal that the elastic constraint induced by the crystallographic orientation affects the remnant polarization values and retention properties of BiFeO3. The in-depth analysis based on the Williamson-Hall plot and thermodynamic analysis manifests that inhomogeneous strain related to the strain relaxation in the film is responsible for the change of the out-of-plane polarization and retention property of BiFeO3 thin films depending on the substrate orientation.

      PubDate: 2017-04-09T06:25:18Z
       
  • Domain engineering in BiFeO3 thin films
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Seung-Hyub Baek, Seokhoon Choi, Taemin Ludvic Kim, Ho Won Jang
      Recent advances in synthesizing complex oxide epitaxial heterostructures with precise control in atomic scale have opened a new era of materials science and engineering research, enabling discoveries of novel physical phenomena even from materials that have been studied for a long time. The exquisite control of high-quality thin films through composition, defects, strain, and microstructure allows us to clearly distinguish intrinsic and extrinsic properties that were obscured by the limitation of sample quality. This is vividly exemplified by the recent research on bismuth ferrite (BiFeO3). Due to the moderately low symmetry of BiFeO3 with a rhombohedral structure, domain engineering, controlling the configuration of domains and domain walls, plays a critical role not only in understanding fundamental physics of electrical and magnetic properties, but also in inducing novel functionalities such as photovoltaic and photocatalysis. In this review, various ways to control domain structures of BiFeO3 will be described with the consequent modification in the physical properties of BiFeO3. This methodology can be expanded to other low-symmetric thin film materials for designing new functionalities.

      PubDate: 2017-04-09T06:25:18Z
       
  • Structural properties of solution-processed Hf0.5Zr0.5O2 thin films
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Jun Young Lee, Gopinathan Anoop, Hyeon Jun Lee, Jeong Hun Kwak, Ji Young Jo
      Hf0.5Zr0.5O2 (HZO) thin films were deposited on Si substrates with and without TiN seed layers using a simple and cost-effective solution synthesis. The crystalline quality of the as-deposited HZO films were improved through a post deposition annealing process. Cross-sectional transmission electron microscope analyses of HZO/TiN/Si structure revealed a clear and clean interface formation between HZO and TiN layers. X-ray diffraction and Raman analyses confirm that, after the post annealing process, HZO films deposited on bare Si substrate crystallized in monoclinic phase while the HZO films deposited on TiN/Si substrates tend to crystallize in tetragonal or orthorhombic crystal structure. Varying crystal structure through controlling the post deposition annealing temperature is a promising technique to manipulate the electrical properties of solution processed HZO thin films.
      Graphical abstract image

      PubDate: 2017-04-09T06:25:18Z
       
  • Structural and physical properties of ZnO on lithium niobates with two
           domains
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): S.H. Chang
      In this paper, we investigated epitaxial ZnO thin films grown on LiNbO3 {0001} substrates with positive (+c) and negative (-c) polarization charges terminated surfaces by using pulsed laser deposition. The polarizations of LiNbO3 substrates can play an important role on modulating structural and physical properties of ZnO thin films. X-ray diffraction studies revealed that the growth behavior of ZnO films was significantly dependent on the temperature and oxygen partial pressure. At the optimal deposition condition, ZnO thin films were grown on two substrates, LiNbO3 (0001) and (000-1) substrates, which have +c and–c domain, respectively. ZnO/LiNiO3(-c) exhibited a sharp rocking curve with highly-oriented out-of-plane than that of ZnO/LiNbO3(+c). The polarization of the substrates was attributed to the carrier concentration and resistance of ZnO layers. After thermal cycles, the resistance between two samples became clearly different due to the elimination of adsorbates, indicating the possibility of polarization-induced charge accumulation in ZnO/LiNbO3 systems.

      PubDate: 2017-04-09T06:25:18Z
       
  • Doping-induced bandgap tuning of α-Ga2O3 for ultraviolet lighting
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Minseok Choi, Junwoo Son
      We propose the novel strategy for indirect-to-direct band gap transition of gallium oxide-based semiconductors for ultraviolet lighting device through first-principles calculations using a screened hybrid functional. Our calculations show that the tuning of electronic band gap of α-Ga2O3 is straightforward by adding dopants, which mimics alloy-like system. In order to put the band gap in the energy range of ultraviolet light, Group-III (In, Tl) at the Ga site and Group-V (N, P) or Group-VI (S, Se) at the O site are examined. We find that the most of doped Ga2O3 possess direct or nearly direct band gaps lying in the ultraviolet energy that is essential for optoelectronic devices.

      PubDate: 2017-04-09T06:25:18Z
       
  • Effect of oxygen intercalation into oxygen-deficient
           SrFe0.8Co0.2O3−δ thin films
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Joonhyuk Lee, Eunyoung Ahn, Yu-Seong Seo, Younghak Kim, Jae-Young Kim, Jungseek Hwang, Yunhyeong Jang, Jinhyung Cho, June Hyuk Lee, Hyoungjeen Jeen
      Controlling oxygen contents is an easy way to tune physical properties in the transition metal oxides. In particular, Fe and/or Co containing oxides are often found to show different electronic states with different valence states by the method. In this report, we synthesized oxygen-deficient SrFe0.8Co0.2O3−δ thin films on (001) (LaAlO3)0.3-(SrAl0.5Ta0.5O3)0.7 substrates by pulsed laser deposition and observed the modification of its electronic state by facile low temperature oxidative annealing. As a result of simple oxidative annealing, we achieved a huge decrease of the lattice constant, reduction in electric resistivity, an increase of the valence states of both Co and Fe, and an increase of hybridization between oxygen and transition metal ions without losing the crystallinity.

      PubDate: 2017-04-09T06:25:18Z
       
  • Highly insulating ferromagnetic cobaltite heterostructures
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Woo Seok Choi, Kyeong Tae Kang, Hyoungjeen Jeen, Zheng Gai, Ho Nyung Lee
      Ferromagnetic insulators are rather rare but possess great technological potential in, for example, spintronics. Individual control of ferromagnetic properties and electronic transport provides a useful design concept of multifunctional oxide heterostructures. We studied the close correlation among the magnetism, atomic structure, and electronic structure of oxide heterostructures composed of the ferromagnetic perovskite LaCoO3 and the antiferromagnetic brownmillerite SrCoO2.5 epitaxial thin film layers. By reversing the stacking sequence of the two layers, we could individually modify the electric resistance and saturation magnetic moment. The ferromagnetic insulating behavior in the heterostructures was understood in terms of the electronic reconstruction at the oxide surface/interfaces and crystalline quality of the constituent layers.

      PubDate: 2017-04-09T06:25:18Z
       
  • Morphology and physical properties of graphene nanoplatelet embedded
           poly(vinyl alcohol) composite aerogel
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Seong Yeol Pak, Zheng Min Huang, Jae Ryoun Youn, Young Seok Song
      Three dimensional carbon nanomaterial reinforced composite aerogel was fabricated using a freeze-drying method. Graphene nanoplatelets (GNPs) were used as the reinforcement and poly vinyl alcohol (PVA) as the organic binding material to produce the composite aerogel. Two different methods were employed to control the internal structure of the aerogel: a variation of solvent composition and the formation of cross-linking. The internal structure of the aerogel was affected by the types and composition of the solvent. In addition, the subsequent cross-linking of the aerogel influenced the morphology and physical properties. It is expected that this study can provide a simple and efficient way to control the internal structure and resulting properties of the GNP aerogel.

      PubDate: 2017-04-09T06:25:18Z
       
  • Effects of Sn-deficiency on thermoelectric properties of polycrystalline
           Sn1-xSe compounds
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Sang Tae Lee, Min Ji Kim, Gil-Geun Lee, Sung Gyoo Kim, Soonil Lee, Won-Seon Seo, Young Soo Lim
      The effects of Sn-deficiency on the thermoelectric properties of polycrystalline Sn1-x Se (x = 0, 0.01, 0.02, and 0.04) compounds were investigated. The Sn-deficiency caused the formation of the SnSe2 secondary phase in the compounds, and the charge and thermal transport properties were affected significantly by the secondary phase. Although the Sn-deficient compounds exhibited higher thermal conductivities than stoichiometric compound due to its high thermal conductivity of SnSe2, significantly improved power factors led to the enhancement of ZT. The highest ZT of 0.61 at 848 K was achieved in Sn0.98Se compound, and detailed effects of SnSe2 on the enhancement were discussed.

      PubDate: 2017-04-09T06:25:18Z
       
  • Magnetic properties and enhanced thermoelectric performance in Cu-doped
           Ca3Co2O6 single crystals
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Jiyue Song, Bangchuan Zhao, Yanan Huang, Yanfeng Qin, Wenhai Song, Yuping Sun
      The effect of Cu doping on the structural, magnetic, electrical and thermal transport properties of Ca3Co2-x Cu x O6 single crystals has been investigated systematically. Based on the analysis of the structural parameter and x-ray photoelectron spectroscopy spectra, the valence state of Cu is considered to be +2. All samples undergo a long-range spin density wave (SDW) transition at T N and a glass-like magnetic transition at T f with decreasing temperature. Both T N and T f decrease monotonously with increasing Cu-doping content. A series of magnetization steps can be observed in the M(H) curve of Ca3Co2O6, and the magnetization steps are sensitive to the sample cooling magnetic field and Cu doping content x. With the increase of x, the resistivity along c-axis decreases while the thermopower increases. As a result, the figure of merit (ZT) increases considerably and the room-temperature ZT value of the sample with x = 0.6 is nearly 60 times larger than that of the un-doped crystal.
      Graphical abstract image

      PubDate: 2017-04-09T06:25:18Z
       
  • Enhanced thermoelectric properties of Ge2Sb2Te5 thin films through the
           control of crystal structure
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): So-Hyun Kang, Venkatraju Jella, S.V.N. Pammi, Ji-Ho Eom, Jin-Seok Choi, Jong-Ryul Jeong, Soon-Gil Yoon
      Tuning the structure and chemical composition of 0.3 μm-thick Ge2Sb2Te5 (GST) films via control of the deposition temperature enhanced thermoelectric performance by balancing the Seebeck coefficient, the electrical conductivity, and the thermal conductivity. By combining the phases of the face-centered cubic (FCC) and hexagonal close packed (HCP) crystal structures of GST thin films deposited at 250 °C, a compromise was attained between a moderate degree of electrical conductivity and the Seebeck coefficient, which resulted in the highest power factor at 1.1 × 10−3 W/K2m. This was attributed to variations in the effective mass, the mixed crystal structure, and the chemical composition with deposition temperature. The highest maximum powers of 0.3 μm- and 1.0 μm-thick n-Bi2Te3 (BT) and p-GST thermoelectric generators with 5 p/n couples were approximately 4.1 and 52.9 nW at ΔT = 12 K, respectively. They showed higher maximum powers than those of referenced n-BT and p-Bi0.5Sb1.5Te3 (BST) thermoelectric generators.

      PubDate: 2017-04-09T06:25:18Z
       
  • Er0.4Bi1.6O3 thin films in situ crystallized at low temperature onto the
           Gd0.1Ce0.9O1.95 bulk electrolytes via Facing-Target Sputtering
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Ji-Na Jeung, Ji-Ho Eom, Byeong-Ju Park, Sun-Dong Kim, Soon-Gil Yoon
      For large-area Er0.4Bi1.6O3 (ESB) films on the Gd0.1Ce0.9O1.95 (GDC) pellets, the 300 nm-thick ESB films were deposited on the 0.2 cm-thick GDC pellets at different temperatures via on-axis sputtering and Facing-Target Sputtering (FTS) for enhancement of the ionic conductivity of the GDC. The ESB films deposited on the GDC pellets via FTS show a good step-coverage and a well-crystallization at a low temperature of 300 °C. The ESB/GDC bilayers with lower activation energy than GDC single layer showed an enhanced ionic conductivity in intermediate-temperature range from 500 to 700 °C. FTS is an attractive method for the ESB film deposition for low-temperature crystallization on the high-roughened GDC pellets.

      PubDate: 2017-04-09T06:25:18Z
       
  • Incorporation of inorganic nanoparticles into an organic polymer matrix
           for data storage application
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Ramneek Kaur, Janpreet Singh, S.K. Tripathi
      The demand of polymer nanocomposite based energy storage devices is in ever increasing stage. Present work demonstrates the application of hybrid polymer nanocomposite (CdSe nanoparticles embedded in poly(N-vinyl carbazole) (PVK) matrix) for data storage devices. CdSe/PVK nanocomposite has been successfully synthesized by ex-situ chemical method. From X-Ray diffraction analysis, Zinc blende structure of CdSe nanoparticles with (111), (220) and (311) cubic crystal planes has been observed. TEM micrograph of CdSe/PVK nanocomposite shows the spherical CdSe nanoparticles having average particle size 6–7 nm, homogeneously dispersed in PVK matrix. CdSe/PVK nanocomposite shows photoluminescence due to the CdSe nanoparticles and p-PVK conformation of PVK. The average surface roughness of the nanocomposite film calculated by using AFM analysis is 45.12 nm. Two-terminal conductivity switching device, structured Al/(CdSe/PVK)/Ag, has been fabricated and characterized. Conductivity switching is due to electron trapping and tunnelling in CdSe nanoparticles and through PVK matrix, respectively. Write-read-erase cycles show a good stability of the device with ON/OFF ratio ∼104. Obtained results reveal the application of CdSe/PVK nanocomposite in data storage devices.

      PubDate: 2017-04-09T06:25:18Z
       
  • Micromagnetic simulations of Permalloy double-dot structures
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Felipe Tejo, Rosa M. Corona, Claudia Arenas, Juan Luis Palma, Juan Escrig
      In this paper we investigate by micromagnetic simulations the magnetic properties of Permalloy double-dot structures as a function of the center-to-center distance between the dots. Generally, a well-defined neck appears in the hysteresis curve, evidencing that the process of magnetization reversal occurs by nucleation and propagation of vortices. However, although the processes of magnetization reversal are similar for different distances between the dots, the coercivities are quite different, primarily due to the different energy contributions that dominate the system. The contribution of the shape anisotropy is important for Permalloy double-dot structures where the distance between the dots is less than their diameters, while the magnetostatic interaction between the two dots predominates if the distance between the dots is greater than their diameters. Finally, there is a critical distance for which the influence of magnetostatic interaction decreases sufficiently so that the interacting system can be considered as an isolated system.

      PubDate: 2017-04-09T06:25:18Z
       
  • Polyvinylidene fluoride/hydroxyapatite/β-tricalcium phosphate
           multifunctional biocomposite: Potentialities for bone tissue engineering
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Taiana G.M. Bonadio, Valdirlei F. Freitas, Tânia T. Tominaga, Ricardo Y. Miyahara, Jaciele M. Rosso, Luiz F. Cótica, Mauro L. Baesso, Wilson R. Weinand, Ivair A. Santos, Ruyan Guo, Amar S. Bhalla
      Bioactive ferroelectric composites based on polyvinylidene fluoride, hydroxyapatite and β-tricalcium phosphate have been synthesized and their structural, microstructural, bioactive, and ferroelectric properties are characterized. Structural and FTIR investigations showed the presence of the polar polyvinylidene fluoride (β2) phase, while ferroelectric characterizations revealed remnant polarizations and coercive field, around 0.04 μC/cm2 and 28 kV/cm, respectively, for these biocompatible samples. Structural and microstructural analysis of samples previously immersed in simulated body fluid for 7 days revealed a large apatite phase growth (1.45 μm) on the composites' surfaces as a strong indication of their elevated bioactivity and potentialities for bone tissue engineering.
      Graphical abstract image

      PubDate: 2017-04-09T06:25:18Z
       
  • Study of temperature-induced structural evolution in
           (Na0.5Bi0.5)TiO3-(K0.5Bi0.5)TiO3-(K0.5Na0.5)NbO3 lead-free ceramics
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Xing Liu, Jiwei Zhai, Bo Shen, Feng Li, Yang Zhang, Peng Li, Baihui Liu
      In this work, the temperature-induced structural evolution in 0.79(Na0.5Bi0.5)TiO3-0.2(K0.5Bi0.5)TiO3-0.01(K0.5Na0.5)NbO3 (NKBNT) lead-free ceramics was investigated by Raman microscopic spectroscopy combined with electrical macroscopic measurements. The NKBNT ceramics possess the local structure with the coexisted rhombohedral R3c and tetragonal P4bm polar-nano-regions (PNRs). The R3c and P4bm PNRs coexist in a wide temperature range, then the local structure transforms to the P4bm PNRs around the temperature of dielectric maximum (T m) evidenced by the doublet splitting of Ti-O modes (peak B) and oxygen octahedral vibrational modes (peak C). The discontinuous changes of wavenumber and line-width of peak B 2 and peak C 3 as well as the dielectric local maxima around the rhombohedral-tetragonal phase transition temperature (T RT) are considered to result from the thermal evolution of R3c and P4bm PNRs. The macroscopic changes of non-polar phase with electric field and temperature were investigated by the temperature-dependent polarization-electric field (P-E) loops, current-electric field (I-E) loops and bipolar strain (S-E) curves. The electric-field level necessary to form the long-range ferroelectric order from non-polar phase associated with the stability of the induced ferroelectric phase depends strongly on the temperature.

      PubDate: 2017-04-09T06:25:18Z
       
  • Impact of Cu2O doping on high dielectric properties of CuO ceramics
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Dan-Dan Wang, Feng-Zi Zhou, Jing-Xiao Cao, Li-Ben Li, Guo-Ling Li
      Single-phase CuO ceramic samples were prepared with the starting nano powders of CuO + xCu2O (x = 0, 1, 3, 7% in mole ratio) via solid state reaction method, and characterized by X-ray diffraction, Raman scattering and scanning electron microscopy. For all the samples, the temperature dependences of dielectric constants and losses were measured at the frequencies of 102, 103, 104, 105 and 106 Hz, respectively. With increasing doping content of Cu2O, a strong correlation is demonstrated at given temperature and frequency between the measured dielectric constants and the unit-cell volumes of CuO. The strong correlation is argued in terms of the change in densities of CuO defects (e.g. Cu/O vacancies and/or interstitial Cu impurities) due to Cu2O doping, which is supported by the formation energies of CuO defects and the corresponding unit-cell volume from first-principles calculations. The high dielectric constant (∼103–105) of CuO ceramic is therefore attributed to the reduction in resistance due to Cu/O defects in the grain by Maxwell-Wagner mechanism.

      PubDate: 2017-04-09T06:25:18Z
       
  • Controlled enzymatic stability and release characteristics of
           supramolecular chiral peptide amphiphile nanofiber gels
    • Abstract: Publication date: May 2017
      Source:Current Applied Physics, Volume 17, Issue 5
      Author(s): Aygul Zengin, Goksu Cinar, Mustafa O. Guler
      Supramolecular bioarchitectures formed by assembly of achiral or chiral building blocks play important roles in various biochemical processes. Stereochemistry of amino acids is important for structural organization of peptide and protein assemblies and structure-microenvironment interactions. In this study, oppositely charged peptide amphiphile (PA) molecules with L-, D- and mixture of l- and d-amino acid conformations are coassembled into supramolecular nanofibers and formed self-supporting gels at pH 7.4 in water. The enzymatic stability of the PA nanofiber gels was studied in the presence of proteinase K enzyme, which digest a broad spectrum of proteins and peptides. The structural changes on the chiral PA nanofibers were also analyzed at different time periods in the presence of enzymatic activity. Controlled release of a model cargo molecule through the chiral PA nanofiber gels was monitored. The diffusivity parameters were measured for all gel systems. Release characteristics and the enzymatic stability of the peptide nanofiber gels were modulated depending on organization of the chiral PA molecules within the supramolecular assemblies.
      Graphical abstract image

      PubDate: 2017-04-09T06:25:18Z
       
  • All-dielectric planar solar cells with multilayer ARC and non-periodic DBR
           nanolayers based on transmission line equivalent circuit
    • Abstract: Publication date: Available online 8 April 2017
      Source:Current Applied Physics
      Author(s): Mohammad Reza Salehi, Mojtaba Shahraki, Ebrahim Abiri
      In this paper, an analytical approach based on transmission line equivalent circuit (TLEC) is used to model planar solar cells. The proposed method has been applied to the all-dielectric planar solar cells with multilayer anti-reflection coating (ARC) and non-periodic distributed Bragg reflector (DBR) nanolayers. This analytical approach is very efficient and easy to be implemented. Consequently, it is straightforward to employ several optimization procedures to determine the optimum thickness for different layers. In this paper, optimization process according to the Fuzzy adaptive modified particle swarm optimization (FAMPSO) algorithm is utilized to maximize the absorption enhancement of these types of solar cells. Results demonstrate the possibility of wideband absorption in all-dielectric planar solar cells and comparable to the conventional light trapping structures.

      PubDate: 2017-04-09T06:25:18Z
       
  • Structurally tunable reflective metamaterial polarization transformer
           based on closed fish-scale structure
    • Abstract: Publication date: Available online 22 March 2017
      Source:Current Applied Physics
      Author(s): Xu Zhang, Zeyong Wei, Yuancheng Fan, Limei Qi
      A reflective metamaterial polarization transformer (RMPT) is proposed with closed fish-scale structure for high efficient cross-polarization reflection. The maximum efficiency of cross-polarization reflection for normal incidence is 97.2%. The RMPT maintains good performance for incident angles up to 25°, and the RMPT is not restricted to a specific polarization state of the incident wave. Furthermore, the designed RMPT shows excellent structural tunability by optimizing the structural parameters, which make it user-friendly.

      PubDate: 2017-03-25T06:05:08Z
       
  • Effect of ytterbium, gold and aluminum transparent metallic substrates on
           the performance of the Ga2S3 thin film devices
    • Abstract: Publication date: Available online 21 March 2017
      Source:Current Applied Physics
      Author(s): S.R. Alharbi, A.F. Qasrawi
      In the current work, the structural, optical, dielectric and electrical properties of the Ga2S3 thin films which are deposited onto transparent thin Al, Yb and Au metal substrates are characterized by means of transmittance electron microscopy, X-ray diffraction, ultraviolet–visible light spectroscopy and impedance spectroscopy techniques. The effects of the metallic substrates on the crystalline nature, energy band gap and dielectric spectra are also investigated. The modeling of the dielectric spectra allowed determining the effect of the Al, Yb and Au thin layers on the electron scattering time, the plasmon frequency, free electron density and drift mobility. In addition, a Yb/Ga2S3/Au Schottky barrier and Al/Ga2S3/Au back to back Schottky barrier devices (metal-semiconductor-metal (MSM) device) are fabricated and characterized by means of capacitance -voltage characteristics and capacitance and conductance spectra in the frequency range of 10–1800 MHz. While the Schottky barrier device displayed three distinct positions of resonance-antiresonance phenomena, the MSM device displayed one peak with narrow bandwidth of 10 MHz. The MSM devices exhibited an inversion, depletion and accumulation modes within a voltage range of 0.25 V width at 250 MHz. The study indicates the applicability of these device as smart capacitive switches, as Plasmon devices and as wavetraps.

      PubDate: 2017-03-25T06:05:08Z
       
  • Growth and characterization of single InGaN quantum well in nonpolar
           a-plane (112¯0) InGaN/GaN light-emitting diodes
    • Abstract: Publication date: Available online 20 March 2017
      Source:Current Applied Physics
      Author(s): Kyuhyun Bang, Sukkoo Jung, Kwang Hyeon Baik, Jae-Min Myoung
      We studied the In incorporation efficiency and composition distribution in a nonpolar a-plane InGaN (a-InGaN) quantum well (QW) layer. The In compositions decreased with increasing growth temperatures due to increased In desorption from InGaN surfaces. It was clear that the In incorporation efficiency on a nonpolar GaN surface is lower than that on a polar c-plane GaN. In addition, the In incorporation rate on an a-InGaN layer could be increased by decreasing the V/III ratio without lowering the growth temperature. In the case of the a-InGaN layer, a composition pulling effect was also observed, suggesting that the In composition of the a-InGaN layer increases along the normal growth direction from the bottom to the top of the InGaN QW layer. Using high-resolution XRD 2θ-ω scans, we found that there existed convex graded In compositions ranging from 4 to 12.7% in an a-InGaN QW layer along the growth direction. No wavelength shift with a current injection of 20–100 mA confirmed the absence of a polarization field. The shift in the electroluminescence (EL) peak energy was ∼11 meV between the electric field parallel and perpendicular to the c-axis components, which was caused by the valence band splitting due to the in-plane compressive strain of the 10 nm a-InGaN QW layer. The EL polarization anisotropy was clearly observed with a polarization ratio of 55%.

      PubDate: 2017-03-25T06:05:08Z
       
  • Electrochemical properties of TiO2-metal oxide composites for
           dye-sensitized solar cell
    • Abstract: Publication date: Available online 18 March 2017
      Source:Current Applied Physics
      Author(s): Hyeong Ryeol Baek, Ik Soo Eo
      The several types of nanofibers were added in dye-sensitized solar cells (DSSCs) and there electrochemical properties were investigated. The surface morphologies of TiO2 electrode was studied by field emission scanning electron microscopy (FE-SEM) and the photoelectrochemical properties of the DSSCs were measured by photovoltaic-current density, AC impedance. By adding the several types of nanofibers we successfully increased the amount of dye loading and enhance the solar conversion efficiency. The pure TiO2 film based DSSC was obtained solar conversion efficiency of 4.8% under irradiation of AM 1.5 (100 mWcm−2). The solar energy conversion efficiency of TiO2 film with 5 wt% SiO2 fiber is 6.2% and it's higher than another fiber (ZrO2, Al2O3 and TiO2). The V oc , J sc , and FF are 0.73 V, 14.23 mA cm−2 and 60%, respectively.

      PubDate: 2017-03-25T06:05:08Z
       
  • High-Tc superconductivity from an atomic point of view via tunneling
    • Abstract: Publication date: Available online 18 March 2017
      Source:Current Applied Physics
      Author(s): Jung Hoon Yoo, Jinho Lee
      Even after 30 years of discovery of the high temperature superconductivity (HTSC) from the cuprate compounds by Bednorz and Müller, the mechanism of the formation of Cooper pairs well above the liquid nitrogen boiling temperature is still remained to be elucidated. The discovery of a yet another HTSC family of the iron-based superconductors seemed to add more complexity to this puzzle, but also seems to render a prospect of finding a universal principle shared by the entire HTSC family. The tunneling experiments, on the other hand, also witnessed remarkable breakthroughs ever since Giaever succeeded the first tunneling experiment on a superconducting aluminum. The scanning tunneling microscopy (STM) invented by Binnig and Rohrer began to be heavily applied to the research of the condensed matter and became one of the most versatile spectroscopic tools as well as the most powerful microscope available also in the HTSC research field as of today. In this review, we would like to convey a snapshot of the current application of the STM in the research of HTSC, mainly focusing on the studies using the spectroscopic imaging scanning tunneling microscopy (SI-STM) which eventually led to the scanning Josephson tunneling microscopy (SJTM) by which we can visualize the superconducting Cooper pairs in an atomic scale.

      PubDate: 2017-03-25T06:05:08Z
       
  • Ruthenium doped carbon aerogel with CO2 surface activation for enhanced
           electrochemical capacitance
    • Abstract: Publication date: Available online 18 March 2017
      Source:Current Applied Physics
      Author(s): Ashish Singh, D.K. Kohli, Sushmita Bhartiya, Rashmi Singh, M.K. Singh, P.K. Gupta
      With the aim of enhancement of electrochemical capacitance, CO2 activation of carbon aerogel (CA) prepared by polycondensation of resorcinol with formaldehyde was performed to obtain activated carbon aerogel (ACA) having improved surface area properties. Ruthenium oxide nano-particles were loaded by impregnation method for utilizing pseudo-capacitive property of ruthenium oxide (RuO2) and the effect of activation treatment was studied. RuO2 loading of 20% by weight was accomplished in CA and ACA to synthesize RuO2 doped carbon aerogel (CA/RuO2) and activated carbon aerogel (ACA/RuO2). While the specific capacitance of carbon aerogel improved from 95 to 153 F/g on activation, RuO2 loading further led to enhancement in capacitance and specific capacitance of 308 F/g was obtained for ACA/RuO2. The studies being important for Ru economy, showed the influence of surface area enhancement of base matrix in achieving high specific capacitance.

      PubDate: 2017-03-25T06:05:08Z
       
  • Anomalously high dielectric strength and low frequency dielectric
           relaxation of a bent-core liquid crystal with a large kink angle
    • Abstract: Publication date: Available online 16 March 2017
      Source:Current Applied Physics
      Author(s): Anoop Kumar Srivastava, Jongyoon Kim, Sunggu Yeo, Jinyoung Jeong, E-Joon Choi, Vijay Singh, Ji-Hoon Lee
      We investigated the dielectric dispersion property of a bent-core liquid crystal (BLC) with a large kink angle in the frequency range of 1.0 Hz–5.5 MHz in a planar aligned cell. Single dielectric dispersion was observed in the smectic A, nematic, and isotropic phase of the planar aligned sample. The dielectric strengths, relaxation frequencies, distribution parameters, and dc conductivity were measured as a function of temperature. The dielectric strength of the observed relaxation mode was anomalously high (∼70), whereas the relaxation frequency was low at ∼500 Hz. The relaxation mode observed in the planar aligned cell was attributed to the fluctuations in the polarization direction due to the cooperative motion of the molecules.

      PubDate: 2017-03-18T09:30:56Z
       
  • Prediction of tensile modulus in polymer nanocomposites containing carbon
           nanotubes (CNT) above percolation threshold by modification of
           conventional model
    • Abstract: Publication date: Available online 16 March 2017
      Source:Current Applied Physics
      Author(s): Yasser Zare, Kyong Yop Rhee
      In this paper, a simple model is developed to predict the tensile modulus of polymer/carbon nanotubes (CNT) nanocomposites (PCNT) above percolation threshold. Since the conventional models such as Ouali and Lyngaae-Jorgensen (L-J) cannot predict the accurate results, a developed model is presented which calculates proper modulus as a function of aspect ratio (α) and volume fraction of CNT at percolation threshold ( ϕ p ) . The developed model can present accurate data, which agree with the experimental results at all filler concentrations. The high ranges of “α” and low values of “ ϕ p ” achieve a desirable modulus. However, a high “ ϕ p ” causes the poor modulus at different “α” demonstrating that the role of “α” is highlighted at slight “ ϕ p ”. It is also possible to calculate the “α” and “ ϕ p ” parameters by applying the developed model to the experimental data of modulus.

      PubDate: 2017-03-18T09:30:56Z
       
  • Multiferroic effect of multilayer low-distorted doped bismuth ferrite thin
           films as a function of sputtering power and crystallographic texture
    • Abstract: Publication date: Available online 16 March 2017
      Source:Current Applied Physics
      Author(s): G. Rojas-George, A. Concha-Balderrama, H. Esparza-Ponce, J.J. Gervacio-Arciniega, M.P. Cruz, V. Orozco-Carmona, A. Reyes-Rojas
      Low-distortion rhombohedral multilayer barium-nickel co-doped BiFeO3 (Bi0.75Ba0.25Fe0.975Ni0.025O3) multiferroic thin films were grown on Pt/TiO2/SiO2/Si substrates by reactive RF magnetron sputtering, as a function of sputtering power. X-ray diffraction showed that Bi0.75Ba0.25Fe0.975Ni0.025O3 multilayer films have a pseudocubic-type structure. Piezoresponse force microscopy demonstrated polarization switching in all films at room temperature. Scanning electron microscopy showed different morphologies depending on the sputtering power used during the deposition process and that the thickness of the film decreases from about 142 nm to 72 nm as the sputtering power decreases. Magnetization results showed that as the thickness of the film decreases, the magnetization of the film increases. Thus, there is a direct relation between the sputtering power, thickness and the magnetization of the film. A direct relation between in-plane residual stress and thin film thickness has been obtained. This causes the main axe of the BO6 octahedra to be tilted from 90 to 45° (from thin-film surface) by a texture crystal volume of 29 and 18% in the (012) and (110) crystallographic planes respectively.
      Graphical abstract image

      PubDate: 2017-03-18T09:30:56Z
       
  • Emission of CdSe quantum dots according to the capping ligands
    • Abstract: Publication date: Available online 9 March 2017
      Source:Current Applied Physics
      Author(s): Min Jung Lee, Jaewon Lee, Ho-Soon Yang, Kyong-Soo Hong
      Quantum dot nanocrystals have particular optical properties due to the quantum confinement effect and the surface effect. This study focuses on the effects of organic materials capping quantum dot on the emission properties of quantum dots. The quantum dots prepared by using 1-hexadecylamine in the synthesis show strong emission, while the quantum dots prepared by using tri-octylphosphine oxide exhibit a suppressed emission and an extra emission related with the surface energy traps. These organic materials cap the quantum dots and make the surface conditions of quantum dots different. TEM images and X-ray diffraction patterns reveal that 1-hexadecylamine constructs a layer on the surface of quantum dot during the synthesis and this surface passivation by a layer of 1-hexadecylamine reduces the surface energy traps. Differently from 1-hexadecylamine, tri-octylphosphine oxide dangles from the surface, which causes a poorly passivated surface. This generates the surface deep trap levels giving rise to a significant and broad emission in the lower energy regime. The optical mechanism is studied by measuring the emission spectra and the time-resolved spectra at various temperatures from 4 K to 300 K.

      PubDate: 2017-03-18T09:30:56Z
       
  • Enhancement of a photovoltaic cell performance by a coupled cooled
           
    • Abstract: Publication date: Available online 9 March 2017
      Source:Current Applied Physics
      Author(s): H. Machrafi
      A new analytical mathematical model is developed, describing a cooled photovoltaic-thermoelectric hybrid system. The thermoelectric material is a nanocomposite where the model takes into account size-dependent non-local thermoelectric properties from an extended thermodynamic point of view. The photovoltaic device powers also the cooling system. The model determines first the optimum thickness of the photovoltaic device, then studies the influence of several size-related parameters on the thermoelectric efficiency (also related to the figure of merit) and finally, coupled to a cooling device, the overall efficiency. For the photovoltaic part, the model is applied to two materials, mono-crystalline and poly-crystalline silicon. The thermoelectric part of the model is applied to an n-leg nanocomposite made out of Sb2Te3 nanoparticles in a Bi2Te3 matrix and of a p-leg nanocomposite made out of Bi2Se3 nanoparticles in a Bi2Te3 matrix. An optimal total photovoltaic device size has been found to be around 127 μm and 1.25 μm for the mono- and poly-crystalline silicon, respectively, leading to efficiencies up to 20%, depending on photovoltaic recombination characteristics. With the cooling device, the overall efficiency was increased by up to an additional 10% (an increase of almost 50%), leading to overall efficiencies around 25%.

      PubDate: 2017-03-18T09:30:56Z
       
  • Silicon carbide (SiC) nanotubes as potential sensors for organophosphate
           molecules
    • Abstract: Publication date: Available online 7 March 2017
      Source:Current Applied Physics
      Author(s): Keyumars Hassanzadeh, Keivan Akhtari, Bahareh Fakhraei, Ghazal Akhtari, Halaleh Hassanzadeh
      The detection and clean-up of the organophosphate (OP) compounds have special importance for those who work in the field of health and governments due to the bad effects of these compounds on human health. In this paper, we have employed the PBE level of theory and ultrasoft pseudopotentials to investigate the ability of silicon carbide nanotubes (SiCNTs) as sensors for organophosphate detection. We found that the binding energy and charge transfer for adsorption of OP on (6,0) SiCNT represents the formation of a strong bond. However, the ΔE Gap demonstrates the significant changes (12%) in the electronic properties of (10,0) SiC nanotubes which could induce considerable alteration in the SiCNT electrical conductivity. According to the results, the OP can be adsorbed on SiCNT and these types of nanotubes can be promising candidates for detecting organophosphate compounds. The non-equilibrium Green function (NEGF) method shows good performance for the sensor sensitivity.
      Graphical abstract image

      PubDate: 2017-03-18T09:30:56Z
       
 
 
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