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ENGINEERING (1240 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 8)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 8)
AASRI Procedia     Open Access   (Followers: 14)
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: 265)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 6)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 3)
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: 7)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 5)
Advanced Science Letters     Full-text available via subscription   (Followers: 9)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 18)
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: 6)
Advances in Engineering Software     Hybrid Journal   (Followers: 27)
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: 13)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 23)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 30)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 43)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Remote Sensing     Open Access   (Followers: 43)
Advances in Science and Research (ASR)     Open Access   (Followers: 4)
Aerobiologia     Hybrid Journal   (Followers: 2)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 6)
AIChE Journal     Hybrid Journal   (Followers: 35)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access   (Followers: 1)
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 26)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 10)
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)
Antarctic Science     Hybrid Journal   (Followers: 1)
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: 18)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 11)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access   (Followers: 3)
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: 5)
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: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
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: 9)
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: 5)
Batteries     Open Access   (Followers: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 26)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 1)
BER : Motor Trade Survey     Full-text available via subscription  
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 1)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bhakti Persada : Jurnal Aplikasi IPTEKS     Open Access  
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 10)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
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: 19)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 35)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
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   (Followers: 1)
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: 15)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 31)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 42)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
Case Studies in Thermal Engineering     Open Access   (Followers: 5)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal  
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: 2)
CienciaUAT     Open Access   (Followers: 1)
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: 13)
City, Culture and Society     Hybrid Journal   (Followers: 20)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 1)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 5)
Coatings     Open Access   (Followers: 4)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 2)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
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: 28)
Composite Interfaces     Hybrid Journal   (Followers: 7)
Composite Structures     Hybrid Journal   (Followers: 271)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 207)
Composites Part B : Engineering     Hybrid Journal   (Followers: 244)
Composites Science and Technology     Hybrid Journal   (Followers: 182)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 15)
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: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computers & Geosciences     Hybrid Journal   (Followers: 30)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 8)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 5)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 33)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 8)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 43)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)

        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  [3175 journals]
  • Influence of deposition pressure and power on characteristics of
           RF-Sputtered Mo films and investigation of sodium diffusion in the films
    • Authors: N. Akcay; N. Akin Sonmez; E.P. Zaretskaya; S. Ozcelik
      Pages: 491 - 499
      Abstract: Publication date: Available online 24 February 2018
      Source:Current Applied Physics
      Author(s): N. Akcay, N. Akin Sonmez, E.P. Zaretskaya, S. Ozcelik
      Mo films deposited by DC sputtering are widely used as back contact in CIGS and CZTS based thin film solar cells. However, there have been only a few studies on the deposition of Mo films by RF sputtering method. In this context, Mo films on SLG substrates were prepared as a function of deposition pressure and power by using RF magnetron sputtering method to contribute to this shortcoming. Mo films were deposited at 250 °C substrate temperature by using 20, 15, 10 mTorr Ar pressures at 120 W RF power and 10 mTorr Ar pressure at 100 W RF power. Structural, morphological and reflectivity properties of RF-sputtered Mo films were clarified by XRD, AFM, FE-SEM and UV–Vis measurements. In addition, due to sodium incorporation from SLG substrate to the absorber layer through Mo back contact layer is so essential in terms of improving the conversion efficiency values of CIGS and CZTS thin film solar cell devices, the effects of Na diffusion in the films were analyzed with SIMS depth profile. The electrical properties of the films such as mobility, carrier density and resistivity were determined by Hall Effect measurements. It was found that Mo films prepared at 120 W, 10 mtorr and 250 °C substrate temperature and then annealed at 500 °C for 30 min, had resistivity as low as 10−5 Ω cm, as well as higher amount of Na incorporation than other films.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.014
      Issue No: Vol. 18, No. 5 (2018)
  • Electrical properties of ion gels based on PVDF-HFP applicable as gate
           stacks for flexible devices
    • Authors: Kwanbyung Chae; Nguyen Duc Cuong; Shinyoung Ryu; Dong-Il Yeom; Y.H. Ahn; Soonil Lee; Ji-Yong Park
      Pages: 500 - 504
      Abstract: Publication date: Available online 24 February 2018
      Source:Current Applied Physics
      Author(s): Kwanbyung Chae, Nguyen Duc Cuong, Shinyoung Ryu, Dong-Il Yeom, Y.H. Ahn, Soonil Lee, Ji-Yong Park
      Electrical characteristics of ion gels prepared by loading different amounts of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM][TFSI] in Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) are investigated and compared with those of ion liquid, [EMIM][TFSI] for possible application as a gate stack for flexible electronic devices. Capacitance and impedance as a function of frequency are measured, which can be well accounted for by a simple circuit model identifying the local device components. The operation of a flexible field effect transistor based on graphene and the ion gel as a top gate stack is also demonstrated.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.017
      Issue No: Vol. 18, No. 5 (2018)
  • Highly crystalline bilayer electron transport layer for efficient
           conjugated polymer solar cells
    • Authors: Cheng Xu; Matthew Wright; Naveen Kumar Elumalai; Md Arafat Mahmud; Dian Wang; Mushfika Baishakhi Upama; Faiazul Haque; Ashraf Uddin
      Pages: 505 - 511
      Abstract: Publication date: Available online 23 February 2018
      Source:Current Applied Physics
      Author(s): Cheng Xu, Matthew Wright, Naveen Kumar Elumalai, Md Arafat Mahmud, Dian Wang, Mushfika Baishakhi Upama, Faiazul Haque, Ashraf Uddin
      Solution processed solar cells are a promising renewable energy technology due to the low fabrication costs. The most commonly used electron transport layer for solution processed organic solar cells is ZnO. However, sol-gel derived ZnO is amorphous, which limits interfacial charge transport. In this study, we demonstrate a ZnO bilayer, composed of a nanoparticle ZnO and sol-gel derived ZnO layer, as the electron transport layer in polymer solar cells incorporating the novel polymer poly [(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3‴-di (2-octyldodecyl)-2,2′; 5′,2″; 5″,2‴-quaterthiophen-5,5‴-diyl)] (PffBT4T-2OD). Compared with the single layer sol-gel ZnO, the bilayer displayed enhanced crystallinity. Consequently, the interfacial transport from the active layer was improved, as evidenced by dark J-V and PL spectroscopy measurements. Solar cells incorporating this bilayer ZnO layer achieved PCE values exceeding 10%, a relative improvement of 25% compared to the sol-gel ZnO devices.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.012
      Issue No: Vol. 18, No. 5 (2018)
  • Effects of deposition parameters on the structure and mechanical
           properties of high-entropy alloy nitride films
    • Authors: T.H. Hsieh; C.H. Hsu; C.Y. Wu; J.Y. Kao; C.Y. Hsu
      Pages: 512 - 518
      Abstract: Publication date: Available online 24 February 2018
      Source:Current Applied Physics
      Author(s): T.H. Hsieh, C.H. Hsu, C.Y. Wu, J.Y. Kao, C.Y. Hsu
      High-entropy alloy (AlCrNbSiTiV)N nitride films are prepared using direct current (dc) reactive magnetron sputtering, with an equiatomic AlCrNbSiTiV alloy target. Experiments using the grey-Taguchi method are conducted to determine the effect of deposition parameters (dc power, substrate temperature, N2/(N2+Ar) flow rate and substrate bias) on the microstructure, mechanical and tribological properties. Orthogonal array (L9 34), signal-to-noise ratio and analysis of variance are used to analyze the effect of the deposition parameters. The coated films are examined using scanning electron microscopy, an atomic force microscope, transmission electron microscopy (TEM), a tribometer and a nanoindenter. The TEM patterns confirm that the (AlCrNbSiTiV)N nitride films have a simple face-center-cubic structure. The experimental results show that a (AlCrNbSiTiV)N film coating significantly improves the mechanical properties. In the confirmation runs, using grey relational analysis, the improvement in friction coefficient is 32.5%, in corrosion current is 28.6%, in hardness H is 29.4%, in elastic modulus E is −18.3%, in H/E is 57.1 and in H3/E2 is 225.0%. The samples with (AlCrNbSiTiV)N film coating are classified as HF1 and exhibit good adhesive strength.
      Graphical abstract image

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.015
      Issue No: Vol. 18, No. 5 (2018)
  • One-step synthesis of TiC/multilayer graphene composite by thermal plasma
    • Authors: Dong-Wook Kim; Un Seon Heo; Kyo-Seon Kim; Dong-Wha Park
      Pages: 551 - 558
      Abstract: Publication date: Available online 16 February 2018
      Source:Current Applied Physics
      Author(s): Dong-Wook Kim, Un Seon Heo, Kyo-Seon Kim, Dong-Wha Park
      Graphene hybrid materials have been attracting a great deal of attention due to their superior properties. Nevertheless, problems such as expensive and complicated production processes have limited their application to industrial fields. Here, we introduce a one-step synthesis of titanium carbide (TiC) nanoparticles on multilayer graphene nanosheet (TiC/multilayer graphene) composites using thermal plasma. Although there are three types of titanium alkoxides (titanium ethoxide, titanium isopropoxide and titanium n-butoxide), the TiC/multilayer graphene was synthesized from only titanium isopropoxide. The injection temperature of the precursor was varied to investigate the effects of the precursor concentration in the plasma region. A TiC/multilayer graphene hybrid material with crystalline TiC nanoparticles below 50 nm on graphene nanosheets was observed. The number of graphene nanosheet layers varied from one to over 10 according to the injection temperature. When titanium ethoxide and titanium butoxide were injected, TiC with amorphous carbon and graphite were synthesized. The formation of graphene is considered to be affected by the structure of the carbon chain in the precursors and the concentration in the plasma region.
      Graphical abstract image

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.006
      Issue No: Vol. 18, No. 5 (2018)
  • The effective stiffness of an embedded graphene in a polymeric matrix
    • Authors: Seyed Mostafa Rahimian-Koloor; Hadi Moshrefzadeh-Sani; Seyed Majid Hashemianzadeh; Mahmood Mehrdad Shokrieh
      Pages: 559 - 566
      Abstract: Publication date: Available online 23 February 2018
      Source:Current Applied Physics
      Author(s): Seyed Mostafa Rahimian-Koloor, Hadi Moshrefzadeh-Sani, Seyed Majid Hashemianzadeh, Mahmood Mehrdad Shokrieh
      Modeling the real sizes of an embedded graphene and the surrounding polymer of a representative volume element in a molecular dynamics simulation is a tedious task. The less computational limitations made the continuum-based method a good candidate for modeling of nanocomposites. However, having a good knowledge of mechanical properties of the embedded graphene in a polymeric matrix is a challenge for employing a continuum-based method. Since the applied stress on the graphene/epoxy nanocomposites has not been directly transferred to the embedded graphene, it brings the following question to mind. Is the stiffness of the embedded graphene different from that of the isolated one' To answer to this question, a model was developed by combining the molecular dynamic simulation and the finite element method to calculate the stiffness of an embedded graphene in a polymeric matrix. The results show that the longitudinal stiffness of the embedded graphene is different from that of the isolated graphene and is a function of its length. The use of this relationship in the micromechanical method leads to consider the nanosize effect in macroscale. The results were compared with some available experimental data to validate the model.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.007
      Issue No: Vol. 18, No. 5 (2018)
  • Investigation of excitonic states effects on optoelectronic properties of
           Sb2Se3 crystal for broadband photo-detector by highly accurate
           first-principles approach
    • Authors: Abdullahi Lawal; A. Shaari; R. Ahmed; L.S. Taura
      Pages: 567 - 575
      Abstract: Publication date: Available online 21 February 2018
      Source:Current Applied Physics
      Author(s): Abdullahi Lawal, A. Shaari, R. Ahmed, L.S. Taura
      The rapid demand of photodetector is increasing day by day due to its versatility of applications that affect our lives. However, it is still very challenging to produce low-cost high-performance broadband photo-detector that can detect light from near infrared to the ultraviolet frequency range for medical diagnosis and visible light communication applications. Regarding this, low-cost antimony selenide (Sb2Se3), with direct energy gap and strong light absorption over a wider range from near infrared to ultraviolet frequency, is considered a promising candidate material for such kind of applications. Therefore, to expose its hidden potential, detailed analysis of its structural, electronic and optical properties is very essential. To accomplish this purpose, different schemes of the first-principles calculations are used in this study. Structural properties of Sb2Se3 are calculated by first-principles methods realized within density functional theory (DFT) framework. Whereas, to compute the quasiparticle (QP) band structure, excitonic and optical properties, many-body perturbation theory (MBPT) based on one-shot GW (G0W0) and Bethe-Salpeter equation (G0W0-BSE) approaches are used. Our DFT calculations show that Wu-Cohen GGA (WC-GGA) reproduces lattice parameters of Sb2Se3 material consistent with the experimental measurements. Similarly, G0W0 calculations confirm the Sb2Se3 a direct bandgap energy material of 1.32 eV and show good agreement with the experimental results. Similarly, the results on the optical properties of Sb2Se3 with the inclusion of electron-hole interaction show that the exciton energy of the material is 1.28eV while its corresponding plasma energy is 10.86 eV. These values show that the investigated material can absorb photons from near infrared to ultraviolet wavelengths. It is, therefore, anticipated that this material will be useful for new-generation optoelectronic applications from near infrared to ultraviolet wavelengths.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.008
      Issue No: Vol. 18, No. 5 (2018)
  • Oxide reduced silicon nanowires
    • Authors: Z.M. Khumalo; M. Blumenthal; M. Topić; C. Funke; J. Bollmann; A. Vantomme; C. Ndlangamandla
      Pages: 576 - 582
      Abstract: Publication date: Available online 21 February 2018
      Source:Current Applied Physics
      Author(s): Z.M. Khumalo, M. Blumenthal, M. Topić, C. Funke, J. Bollmann, A. Vantomme, C. Ndlangamandla
      Core crystalline silicon nanowires with a heavily reduced amorphous shell have been successfully synthesised using palladium as a metal catalyst. We present two approaches to reduce the oxidation of the nanowires during the thermal annealing growth. The ratios of the amorphous shell to crystalline core of the nanowires produced, from the two methods, are compared and show a remarkable drop (hence thinner oxide) compared to wires fabricated using currently available techniques. In addition, a focused ion beam was utilised to contact the oxide-reduced nanowires for transport measurements, without first removing the thin oxide shell. The oxygen-reduced core-shell silicon nanowires showed a very low electrical resistivity (4 × 10−1 Ω cm). Our novel approach presents a new alternative to the production of low cost, high yield, highly conducting silicon nanowires offering a wide range of opportunities for semiconductor based technology.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.010
      Issue No: Vol. 18, No. 5 (2018)
  • Solution-processed WOx hole injection layer for efficient fluorescent blue
           organic light-emitting diode
    • Authors: Wanshu Li; Yan Zhang; Qinghong Zheng; Kai Xu; Xiuyun Zhang; Liming Liu; Bin Wei; Lihui Wang; Jiwen Xu; Xiaowen Zhang
      Pages: 583 - 589
      Abstract: Publication date: Available online 23 February 2018
      Source:Current Applied Physics
      Author(s): Wanshu Li, Yan Zhang, Qinghong Zheng, Kai Xu, Xiuyun Zhang, Liming Liu, Bin Wei, Lihui Wang, Jiwen Xu, Xiaowen Zhang
      Solution-processed tungsten oxide (s-WOx) interfacial layer for efficient hole injection in fluorescent blue organic light-emitting diode (OLED) is demonstrated. The OLED using 2-methyl-9,10-bis(naphthalen-2-yl)anthracene (MADN) as emitter shows luminous efficiency of 3.3 cd/A, power efficiency of 2.5 lm/W and external quantum efficiency of 4.6% with Commission Internationale d'Eclairage (CIE) color coordinates of (0.154, 0.102). Using MADN doped 1-4-di-[4-(N,N-diphenyl)amino]styryl-benzene as emitter, luminous efficiency of 10.8 cd/A, power efficiency of 6.4 lm/W and external quantum efficiency of 7.2% with CIE color coordinates of (0.167, 0.283) are achieved. Atomic force microscopy and X-ray photoelectron spectroscopy show that s-WOx features superior film morphology and non-stoichiometry with slight oxygen deficiency. Current-voltage characteristics and impedance spectroscopy analysis indicate that s-WOx behaves slightly enhanced hole injection and accordingly contributes to improved device performance in comparison with conventional vacuum thermal evaporation WOx. Our results pave an alternative way for broadening WOx application with solution process and advancing fluorescent blue OLEDs.
      Graphical abstract image

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.011
      Issue No: Vol. 18, No. 5 (2018)
  • Structural and magnetic properties of Ga-substituted Co2−W
    • Authors: Sami H. Mahmood; Qusai Al Sheyab; Ibrahim Bsoul; Osama Mohsen; Ahmad Awadallah
      Pages: 590 - 598
      Abstract: Publication date: Available online 24 February 2018
      Source:Current Applied Physics
      Author(s): Sami H. Mahmood, Qusai Al-Shiab, Ibrahim Bsoul, Osama Mohsen, Ahmad Awadallah
      Precursor powders of BaCo2Fe16-x Ga x O27 with 0.0 ≤ x ≤ 0.8 were prepared using high-energy ball milling, and the effects of chemical composition on the structural and magnetic properties of the powders sintered at 1300 °C were investigated using x-ray diffractometer (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). XRD patterns of all samples indicated crystallization of pure BaCo2−W (BaCo2Fe16O27) hexaferrite phase. SEM measurements revealed large step-like formations with hexagonal crystallites. The magnetic data revealed small fluctuations of the saturation magnetization below the value 72.56 emu/g corresponding to the unsubstituted sample. The coercive field H c of all samples ranged between 70 Oe and 130 Oe, indicating soft magnetic phase. Curie temperature determined from the thermomagnetic curves of the samples decreased from 485 °C at x = 0.0 down to 451 °C at x = 0.6. Also, the thermomagnetic curves revealed the presence of a minority magnetic phase with enhanced superexchange interaction, and the occurrence of complex magnetic phase transitions associated with spin reorientation transitions above room temperature.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.013
      Issue No: Vol. 18, No. 5 (2018)
  • Simultaneous reduction and sulfonation of graphene oxide for efficient
           hole selectivity in polymer solar cells
    • Authors: Asghar Ali; Zuhair S. Khan; Mahmood Jamil; Yaqoob Khan; Nisar Ahmad; S. Ahmed
      Pages: 599 - 610
      Abstract: Publication date: Available online 24 February 2018
      Source:Current Applied Physics
      Author(s): Asghar Ali, Zuhair S. Khan, Mahmood Jamil, Yaqoob Khan, Nisar Ahmad, S. Ahmed
      We developed sulfonated, reduced graphene oxide (S-RGO) through fuming/concentrated sulfuric acid treatment of graphene oxide (GO) in ambient conditions. It was demonstrated that the optical band gap and electrical conductivity of S-RGO are easily tunable, and depend on the level of reduction and sulfonation of GO. Whereas, reduction and sulfonation were found dependent on SO3 content, acid strength, and gas tightness of the reaction mixture. It's actually the water content of oleum that determines the nature of the final product. The easily adjustable band gap and electrical conductivity suggest that S-RGO can be employed as a potential hole extraction layer (HEL) material for several donor-acceptor systems. For P3HT:PC61BM based inverted polymer solar cells, it was observed that the shape of the J–V curve is tailorable with the choice of HEL. Compared to a 2.75% power conversion efficiency (PCE) attained with PEDOT:PSS, a PCE of 2.80% was achieved with tuned S-RGO. Our results imply that an S-RGO of sufficiently high band gap and conductivity can replace some of the state of the art HEL materials for a host of device applications.
      Graphical abstract image

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.016
      Issue No: Vol. 18, No. 5 (2018)
  • Realization of enhanced sound-driven CNT-based triboelectric
           nanogenerator, utilizing sonic array configuration
    • Authors: M. Javadi; A. Heidari; S. Darbari
      Pages: 361 - 368
      Abstract: Publication date: April 2018
      Source:Current Applied Physics, Volume 18, Issue 4
      Author(s): M. Javadi, A. Heidari, S. Darbari
      Triboelectric nanogenerators have been emerged as the most promising mechanical energy harvesters, during last few years. Here, a sonic triboelectric nanogenerator with 7-fold enhanced output power is reported, in which carbon nanotubes are utilized to increase the electrode's effective surface area. To improve the efficiency we have taken advantage of acoustic wave localization in a sonic array. For this purpose, first we have studied an array of periodic acoustic scatterers by simulation. Then, we have designed a 1-D phononic crystal consisting of five steel slabs standing in air medium, which leads to resonance of incident acoustic wave at f = 4.34 kHz. We implemented the design, but replaced the middle scatterer by triboelectric nanogenerator. An enhancement factor of about 4 has been measured for the output voltage of the sonic nanogenerator at f = 4.24 kHz, when it is embedded in the sonic array. Also, power enhancement factor of 7-fold has been achieved (Pout≈4 μW/m2), benefiting from the applied sonic cavity. The measured resonance frequency and enhancement factor are in acceptable agreement with the simulation results. The presented enhanced energy harvesting configuration proposes a compact and low cost structure, which allows parallel energy harvesting, and seems promising for realizing sonic harvesters.
      Graphical abstract image

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.01.018
  • Interface and bulk properties of Cu(In,Ga)Se2 solar cell with a
           cracker-ZnS buffer layer
    • Authors: Woo-Jung Lee; Dae-Hyung Cho; Jisu Yoo; Jengsu Yoo; Jae-Hyung Wi; Won Seok Han; Yoonsung Nam; Yeonjin Yi; Soo-Kyung Chang; Yong-Duck Chung
      Pages: 405 - 410
      Abstract: Publication date: April 2018
      Source:Current Applied Physics, Volume 18, Issue 4
      Author(s): Woo-Jung Lee, Dae-Hyung Cho, Jisu Yoo, Jengsu Yoo, Jae-Hyung Wi, Won Seok Han, Yoonsung Nam, Yeonjin Yi, Soo-Kyung Chang, Yong-Duck Chung
      Cu(In,Ga)Se2 (CIGS) solar cells were fabricated by varying the film thickness of the cracker-ZnS (c-ZnS) buffer layer from 0 nm to 20 nm, and performance was found to depend on c-ZnS film thickness. The best cell efficiency of approximately 8% was obtained from the CIGS solar cell with an 8 nm thick-c-ZnS buffer layer. To investigate the primary factor to determine the cell performance, we utilized the impedance spectroscopy (IS) reflecting interface qualities, and capacitance-voltage (CV) profiling sensitive to bulk properties. In IS results, an equivalent circuit model including the resistance and capacitance was proposed to interpret cell performance, and carrier lifetime was obtained in connection with recombination probability at p-n junction. In CV profiling, the carrier concentration in the CIGS bulk, the depletion width, and the charge distribution related to the defect states along the depth direction were evaluated. The formation mechanism of c-ZnS buffer layer is suggested by measuring the chemical states, which is closely associated with the IS and CV results. The depletion width substantially increased at c-ZnS film thickness more than 15 nm due to the diffusion of Zn atoms toward CIGS layer, resulting in negative influence on cell performance. From this study, we demonstrated that IS and CV profiling are complementary analysis tools for interpretation of the solar cell operation concerning the interface and bulk properties.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.003
  • Unusual flow behavior of Fe-based soft magnetic amorphous ribbons under
           high temperature tensile loading
    • Authors: Jiyun Oh; Jin-Yoo Suh; Woo-Jin Kim; Jae-il Jang; Ki Hoon Kang; Chong Seung Yoon; Haein Choi-Yim
      Pages: 411 - 416
      Abstract: Publication date: April 2018
      Source:Current Applied Physics, Volume 18, Issue 4
      Author(s): Jiyun Oh, Jin-Yoo Suh, Woo-Jin Kim, Jae-il Jang, Ki Hoon Kang, Chong Seung Yoon, Haein Choi-Yim
      The viscous thermal flow behavior and mechanical property of [Fe0.6Co0.15B0.2Si0.05] (100−x)Tax (x = 0, 1, 2, 3, 4, and 5) soft magnetic amorphous ribbons were studied. The characteristics of melt-spun amorphous ribbons were measured by using vibration sample magnetometer (VSM), nanoindentation, differential scanning calorimetry (DSC) and thermo-mechanical analysis (TMA) to study the effects of Ta content variation on the thermal stability, mechanical, and soft magnetic properties. We observed that the nanoindentation hardness, Young's modulus, and glass transition and crystallization temperatures were improved by the addition of Ta. Using dilatometry measurement, TMA, by heating at a constant rate under tension mode, we examined not only the glass transition and crystallization behaviors but also the possibility of coexistence of multiple amorphous phases.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.005
  • Nitrogen doped carbon nano-onions as efficient and robust electrocatalysts
           for oxygen reduction reactions
    • Authors: Yan Zhang; Allen Reed; Doo Young Kim
      Pages: 417 - 423
      Abstract: Publication date: April 2018
      Source:Current Applied Physics, Volume 18, Issue 4
      Author(s): Yan Zhang, Allen Reed, Doo Young Kim
      We investigated synthesis and electrocatalytic performance of metal-free, nitrogen-doped carbon nano-onions (N-CNOs) for oxygen reduction reactions in alkaline electrolyte. N-CNOs were prepared by chemical oxidation of nanodiamond-derived carbon nano-onions (ox-CNOs), followed by thermal annealing with urea under the flow of argon gas. The chemical oxidation step was critical to successfully internalize nitrogen atoms into carbon network. Morphology, microstructure, and chemical states of carbon nano-onions (CNOs), ox-CNOs, and N-CNOs were characterized by transmission electron microscopy (TEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Electrocatalytic activity of pristine and modified CNOs was characterized by a series of electrochemical measurements. Electrochemical characterizations were done with thin film electrodes of CNOs mounted on a glassy carbon disk. Compared to CNOs and ox-CNOs, N-CNOs showed remarkably enhanced electron-transfer kinetics with the 4-electron transfer as a dominant reaction pathway. Overall, N-CNOs exhibited electrochemical characteristics comparable to commercial Pt/C catalysts.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.001
  • Central spot formed in dried coffee-water-mixture droplets: Inverse
           coffee-ring effect
    • Authors: Ji Min Baek; Changhyun Yi; Joo Yull Rhee
      Pages: 477 - 483
      Abstract: Publication date: Available online 2 February 2018
      Source:Current Applied Physics
      Author(s): Ji Min Baek, Changhyun Yi, Joo Yull Rhee
      We have investigated the formation of central spot when coffee-water-mixture droplets are dried, which is a reverse effect of the famous coffee-ring effect (CRE). Typically, the central spot is unnoticeable or ignored even though it is significant. The ring-shaped stain is due to the capillary flow (CF). The CF is caused by the difference in the evaporation rates between the edge and the center of the droplet owing to a temperature gradient. The same temperature gradient, however, causes the so-called Marangoni flow (MF). The MF is routinely ignored, particularly when the solvent is water. However, from experiments, we found that, in addition to the ring-shaped stain formed by the CRE, central spot is formed. When the volume of a droplet of coffee-water mixture is ∼ 15 μL, the strongest central spot is formed We employed an improved enhanced heat-transfer model, in which the shape of the droplet was assumed to be spheroidal, to understand the effects of the MF on the central-spot formation. According to the model, the formation of central spot can be explained, at least, semi-quantitatively. As a result of the existence of a stagnation point, the direction of flow is changed. Furthermore, the dependence of its location on the initial geometrical parameters of the droplet is very important. In addition, the effect of gravity was investigated for pendant droplets. The central-spot formation is more prominent in pendant droplets than in sessile droplets because the gravity enhances the MF in the pendant droplets, while it hinders the MF in the sessile droplets.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.01.007
  • OPE molecular junction as a hydrogen gas sensor
    • Authors: Jian-Guo Xin; Chuan-Lu Yang; Mei-Shan Wang; Xiao-Guang Ma
      Pages: 273 - 279
      Abstract: Publication date: March 2018
      Source:Current Applied Physics, Volume 18, Issue 3
      Author(s): Jian-Guo Xin, Chuan-Lu Yang, Mei-Shan Wang, Xiao-Guang Ma
      Oligo(phenylene ethynylene) (OPE) molecular junction has been suggested as a H2 molecule sensor based on calculations using the first principles of density–functional theory and non-equilibrium Green's function. The electronic transport properties of the OPE molecule between two Au electrodes with or without adsorbed H2 molecules are investigated. Results show that the adsorbed H2 molecule significantly changes the characteristics of the current–voltage curve of the OPE molecular junction. The pure OPE molecular junction exhibits a significant negative differential resistance, but this kind of phenomenon will disappear or weaken after hydrogen molecules are adsorbed. The conductance of the junction also obviously decreases in the bias range of [−0.4, 0.4] V after adsorbing H2 molecules. These effects can be used to design a H2 molecule sensor.
      Graphical abstract image

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2018.01.002
  • First principles studies on the elastic, thermodynamic properties and
           electronic structure of Ti15−xMoxSn compounds
    • Authors: Chunmei Chen; Wei He; Lijing Ding; Xiaohui Song; Jinhui Huang; Tao Wang; Guoren Huang
      Pages: 280 - 288
      Abstract: Publication date: March 2018
      Source:Current Applied Physics, Volume 18, Issue 3
      Author(s): Chunmei Chen, Wei He, Lijing Ding, Xiaohui Song, Jinhui Huang, Tao Wang, Guoren Huang
      The structural, elastic, thermodynamic and electronic properties of the Ti15−xMoxSn compounds were systematically investigated by means of first-principles calculations based on the density functional theory (DFT). The calculated results demonstrate the Ti15−xMoxSn compounds still remain the stable β phase structure. The calculation of cohesive energy shows that the structural stability of the Ti15−xMoxSn compounds increases apparently with the increase of Mo content. According to Hooke's law, the single crystal elastic constants were obtained and show that all the calculated compounds keep mechanical stability. Then the bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν of polycrystalline aggregates were calculated at zero pressure. The calculated results show that among these Ti15−xMoxSn compounds, Ti4Mo11Sn exhibits the largest stiffness while Ti12Mo3Sn shows the greatest ductility. The compounds Ti12Mo3Sn and Ti11Mo4Sn with the two lowest elastic Young's modulus of 61.01 GPa and 65.59 GPa are expected to be promising metallic biomaterials for implant applications. Besides, the Debye temperature Θ D and the electronic density of states (DOS) are also investigated and discussed.

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2017.12.008
  • Facile preparation and performance of novel high-TC
           xBi(Ni1/2Ti1/2)O3-(1-x)Pb(Zr1/2Ti1/2)O3 piezoceramics
    • Authors: Wanwan Ji; Shuai Feng; Bijun Fang; Xiangyong Zhao; Shuai Zhang; Jianning Ding; Haosu Luo
      Pages: 289 - 296
      Abstract: Publication date: Available online 5 January 2018
      Source:Current Applied Physics
      Author(s): Wanwan Ji, Shuai Feng, Bijun Fang, Xiangyong Zhao, Shuai Zhang, Jianning Ding, Haosu Luo
      High Curie temperature (TC) xBi(Ni1/2Ti1/2)O3-(1-x)Pb(Zr1/2Ti1/2)O3 (xBNT-(1-x)PZT, BNT-PZT) piezoelectric ceramics were prepared by the conventional ceramic processing. The composition-induced morphotropic phase boundary (MPB) and its influences on structure and electrical performance were investigated. The synthesized BNT-PZT ceramics exhibit rather pure perovskite structure, and densified microstructure morphology with uniform elementals distribution in both grains and grain boundaries. With increasing the content of Bi(Ni1/2Ti1/2)O3 (BNT), crystal structure of the BNT-PZT ceramics transform from tetragonal phase to rhombohedral phase, and dielectric response peaks change from narrow shape to very broad shape but all presenting dielectric frequency dispersion. The diffused and relaxation dielectric behavior can be fitted well by the quadratic law, and the Vogel-Fulcher law fitting provides additional information on the relaxation characteristic. The MPB effects are confirmed further by ferroelectric and piezoelectric properties measurements. High-TC combined with excellent piezoelectric performance can be realized in the BNT-PZT system, which presents promising applications in geothermal exploration, aerospace and related elevated temperatures fields.

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2017.12.007
  • Effect of electrochemical reduction on the structural and electrical
           properties of anodic TiO2 nanotubes
    • Authors: Muhammad Asim Rasheed; Kamran Ahmad; Nilem Khaliq; Yaqoob Khan; Muhammad Aftab Rafiq; Abdul Waheed; Attaullah Shah; Arshad Mahmood; Ghafar Ali
      Pages: 297 - 303
      Abstract: Publication date: Available online 9 January 2018
      Source:Current Applied Physics
      Author(s): Muhammad Asim Rasheed, Kamran Ahmad, Nilem Khaliq, Yaqoob Khan, Muhammad Aftab Rafiq, Abdul Waheed, Attaullah Shah, Arshad Mahmood, Ghafar Ali
      The effect of electrochemical reduction on the structural and electrical properties of amorphous as well as annealed TiO2 nanotubes (TNTs) is investigated under ambient conditions. TNTs were prepared by anodizing titanium sheet in ethylene glycol electrolyte containing NH4F and de-ionized water at 40 V for 6 h. Electrochemical reduction is carried out in 1 M aqueous KOH solution for ∼15 s at 3 V. TNTs are characterized by SEM, XRD, XPS and impedance spectrometer. XRD results confirm an increase in d-spacing for (101) and (200) planes, after electrochemical reduction. XPS data reveal that electrochemical reduction produced prominent shifts of ∼0.7–1.0 eV in the binding energies of TNTs. Interestingly, these shifts recover completely (in case of amorphous TNTs) and partially (in case of anatase TNTs) within ∼7 days after reduction process due to oxygen uptake. Partial recovery in the binding energies of anatase TNTs is due to the fact that the oxygen vacancies are thermodynamically more stable compared to amorphous TNTs. Similarly, the electrochemical reduction process decreases the impedance values of TNTs by more than three orders of magnitudes (from MΩ to kΩ). The impedance values also recover to the similar values before reduction in a span of ∼7days.

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2018.01.001
  • Prediction on the physical properties of CuInS2 with various anion
    • Authors: Yiming Ren; Yonghong Hu; Haibo Zeng; Li Xue
      Pages: 304 - 309
      Abstract: Publication date: March 2018
      Source:Current Applied Physics, Volume 18, Issue 3
      Author(s): Yiming Ren, Yonghong Hu, Haibo Zeng, Li Xue
      The effects of various anion displacements (u) on electronic structures, elastic constants, Debye temperature and the minimum thermal conductivity of CuInS2 are studied by first-principles calculation. The lattice constant couples with the anion displacement, however, they are not consistent with the relation proposed by Abrahams and Bernstein. When the anion displacement varies from 0.2 to 0.3, the Cu-S bond length is elongated, while the In-S bond length is shortened, which cause the increase of band gap with anion displacement. The anisotropies of sound velocities and lattice thermal conductivities are also discussed. The results imply that the lattice thermal conductivity along [110] direction is the smallest and decreases with u. These research findings shed light on improving the thermoelectric properties by manipulating u and the direction of propagation.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.01.005
  • Local symmetry distortion-induced enhancement of upconversion luminescence
           in Gd2O3:Ho3+/Yb3+/Zn2+ nanoparticles for solid-state lighting and
    • Authors: Peng Du; Eun-Joong Kim; Jae Su Yu
      Pages: 310 - 316
      Abstract: Publication date: Available online 9 January 2018
      Source:Current Applied Physics
      Author(s): Peng Du, Eun-Joong Kim, Jae Su Yu
      The Ho3+/Yb3+/Zn2+-tridoped Gd2O3 nanoparticles were prepared by a simple urea-based homogeneous precipitation method. Under near-infrared (NIR) light excitation, all the synthesized nanoparticles exhibit bright green and red upconversion (UC) emissions corresponding to the intra-4f transitions of Ho3+ ions and the UC mechanism is found to be a two-photon process. With the introduction of Zn2+ ions, not only the local symmetry surrounding the dopants is decreased, but also the UC emission intensity is also enhanced, which is further verified by the Judd-Ofelt theory. The temperature-dependent UC emission spectra were recorded to examine the thermal stability of the final products. From theoretical calculations, the activation energy is demonstrated to be about 0.18 eV. A novel green light-emitting diode device, which consists of the resultant nanoparticles and a NIR chip, was fabricated to state their suitability for solid-state lighting. Meanwhile, the synthesized nanoparticles exhibit low cytotoxicity in various cell lines, suggesting their potential applications in in vivo UC luminescence imaging. Additionally, the applicability of the Ho3+/Yb3+/Zn2+-tridoped Gd2O3 nanoparticles for in vivo bioimaging applications was also analyzed.

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2018.01.004
  • Understanding the friction behavior of sulfur-terminated diamond-like
           carbon films under high vacuum by first-principles calculations
    • Authors: Renhui Zhang; Juan Zhao; Yingchang Yang; Wei Shi; Zhibin Lu; Junjun Wang
      Pages: 317 - 323
      Abstract: Publication date: March 2018
      Source:Current Applied Physics, Volume 18, Issue 3
      Author(s): Renhui Zhang, Juan Zhao, Yingchang Yang, Wei Shi, Zhibin Lu, Junjun Wang
      Generally, the repulsive force was a key factor account for superlow friction of H or F doped diamond-like carbon (DLC) films under high vacuum. As we known, H or F doped DLC usually exhibited superlow friction under high vacuum. However, the superlow friction of S doped DLC under high vacuum was not found so far. This phenomenon was desirable to be well investigated. In this work, S-terminated diamond interfaces also exhibited strong repulsive force, however, the estimated friction coefficient was variable for S-terminated diamond interfaces. The lowest and largest friction coefficient was about 0.003 and 0.4 respectively, which indicated that the superlow friction of S doped DLC could achieve in theory. In order to well probe the unusual friction behavior of S doped DLC under high vacuum, using first-principles method, the repulsive interaction between sliding surfaces was well investigated in order to understand the unusual friction behavior of S doped DLC films.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.01.006
  • Ferroelectric polarization effect on hysteresis behaviors of single-walled
           carbon nanotube network field-effect transistors with lead
           zirconate-titanate gating
    • Authors: Yilin Sun; Dan Xie; Ruixuan Dai; Mengxing Sun; Weiwei Li; Tianling Ren
      Pages: 324 - 328
      Abstract: Publication date: Available online 9 January 2018
      Source:Current Applied Physics
      Author(s): Yilin Sun, Dan Xie, Ruixuan Dai, Mengxing Sun, Weiwei Li, Tianling Ren
      We report the fabrication of single-walled carbon nanotube (SWCNT) network transistors by ferroelectric Pb(Zr0.4Ti0.6)O3 (PZT) bottom-gating and investigate the polarization effects of PZT on the transport properties of the transistor device. Our devices exhibit typical p-channel transistor characteristics and a large hysteresis loop with high ON/OFF current ratio and large ON current as well as memory window (MW) measured up to 5.2 V. The origin of clockwise hysteresis is attributed to ferroelectric polarization modulated charge trapping/de-trapping process in the interface states between SWCNT networks and PZT. The retention time about 104s with two high stable current states preliminarily demonstrates great potential for future non-volatile memory applications based on such SWCNT/PZT hybrid systems.

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2018.01.003
  • Petal-like MoS2 nanostructures with metallic 1 T phase for high
           performance supercapacitors
    • Authors: Rajneesh Kumar Mishra; Shanmugam Manivannan; Kyuwon Kim; Hyuck-In Kwon; Sung Hun Jin
      Pages: 345 - 352
      Abstract: Publication date: March 2018
      Source:Current Applied Physics, Volume 18, Issue 3
      Author(s): Rajneesh Kumar Mishra, Shanmugam Manivannan, Kyuwon Kim, Hyuck-In Kwon, Sung Hun Jin
      Herein, we report the metallic 1 T phase MoS2 petal-like nanostructures (MP-LNs), synthesized by the solvothermal method, for applications in supercapacitor electrodes. X-ray photoelectron spectroscopy (XPS) verified the composition and distribution of Mo and S, illustrating that the 1 T metallic phase is predominant in the MP-LNs. Electrochemical analyses were performed to explore the supercapacitor applications of the MP-LN material, demonstrating a superior cyclic voltammetry (CV), high specific capacitance, good stability. MP-LN-based supercapacitors (MP-LNS) show high specific capacitances of 811 F/g and 400 F/g at current densities of 0.1 A/g and 10 A/g, respectively. The long-term cycling stability was also studied to investigate the reproducible nature of MP-LNS and was found to display excellent specific capacitance retention of 49.3% (at 0.1 A/g) and 82.7% (at 10 A/g) after 1000 charge-discharge cycles, which indicates good reversibility of the galvanostatic charge-discharge (GCD) of the electrode material. These findings highlight the potential use of MP-LNs in supercapacitors.
      Graphical abstract image

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2017.12.010
  • Structural and electrical properties of VO2/ZnO nanostructures
    • Authors: Zhenlan Jin; In-Hui Hwang; Chang-In Park; Sun-Hong Park; Sang-Wook Han
      Pages: 353 - 359
      Abstract: Publication date: March 2018
      Source:Current Applied Physics, Volume 18, Issue 3
      Author(s): Zhenlan Jin, In-Hui Hwang, Chang-In Park, Sun-Hong Park, Sang-Wook Han
      We examined the structural and electrical properties of uniformly-oriented VO2/ZnO nanostructures. VO2 was deposited on ZnO templates by using a direct current-sputtering deposition. Scanning electron microscope and transmission electron microscope measurements indicated that b-oriented VO2 were uniformly crystallized on ZnO templates with different lengths. VO2/ZnO formed nanorods on ZnO nanorods with length longer than 250 nm. X-ray absorption fine structure at the V K edge of VO2/ZnO showed M1 and R phases of VO2 at 30 and 100 °C, respectively, suggesting structural-phase transition occurring between the two temperatures. Temperature-dependent resistance measurements of VO2/ZnO nanostructures revealed metal-to-insulator transition at 65 °C and 55 °C during a heating and a cooling, respectively, regardless of ZnO length. Asymmetry behavior of resistance curves from VO2/ZnO nanostructure during a heating and a cooling was attributed from a strong bond of VO2 and ZnO.

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2017.12.009
  • Colloidal stability measurements of graphene nanoplatelets covalently
           functionalized with tetrahydrofurfuryl polyethylene glycol in different
           organic solvents
    • Authors: Siti Shafiah Shazali; Ahmad Amiri; Mohd Nashrul Mohd Zubir; Shaifulazuar Rozali; Mohd Zakuan Zabri; Mohd Faizul Mohd Sabri
      Pages: 209 - 219
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Siti Shafiah Shazali, Ahmad Amiri, Mohd Nashrul Mohd Zubir, Shaifulazuar Rozali, Mohd Zakuan Zabri, Mohd Faizul Mohd Sabri
      In this study, a facile, efficient, and cost-effective method was proposed for mass-production of tetrahydrofurfuryl polyethylene glycol-functionalized graphene nanoplatelets (TFPEG-treated GNPs) with improved colloidal stability in water and different organic solvents. In this method, zirconium(IV) oxychloride octahydrate was used as catalyst to covalently functionalize GNPs with TFPEG via direct esterification of carboxylic acid on the GNPs with the hydroxyl chains of TFPEG. Covalent functionalization was verified by Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis. Further, the morphology of the TFPEG-treated GNPs was determined via a high-resolution transmission electron microscopy. The stability of the treated GNPs in colloidal form was examined by dispersing 0.01 wt% of the solid sample into different organic solvents namely distilled water, methanol, ethanol, ethylene glycol, and 1-hexanol. It was found that the sedimentation rate of TFPEG-treated GNPs in distilled water, methanol, ethanol, ethylene glycol, and 1-hexanol was at 11, 25, 36, 18, and 47%, respectively, recorded after 15 days. Viscosity and thermal conductivity of water-based TFPEG-treated GNP nanofluids were also measured at different concentrations (0.100, 0.075, 0.050, and 0.025 wt%). The results suggest that these nanofluids have great potential for use as working fluids in industrial heat transfer systems.
      Graphical abstract image

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2017.10.007
  • Electric field involved transport at elevated temperature in
           nanocrystalline silicon carbide nitride (nc-SiCN) thin films for harsh
           environment applications
    • Authors: Narendra Singh; Kirandeep Singh; Davinder Kaur
      Pages: 220 - 225
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Narendra Singh, Kirandeep Singh, Davinder Kaur
      The present study represents a systematic temperature dependent charge transport and dielectric properties of nanocrystalline silicon carbide nitride (nc-SiCN) thin films grown on Pt/Ti/SiO2/Si substrate. A large negative temperature coefficient of resistance (TCR) ranging from 6200 to 2300 ppmK-1 in the temperature range 300–773 K, suggests that the nc-SiCN thin films could be useful for futuristic thermal-based sensors. The current density vs. electric field (J-E) characteristics was measured at different temperatures (300–673 K). Detailed J-E analysis revealed an ohmic conduction at the low applied electric field (<65 kV/cm) within the entire temperature range. However, at high electric field (>65 kV/cm), space charge limited conduction (SCLC) mechanism was found to be dominating in low measurement temperature (300–473K), whereas, a transition from SCLC mechanism to Poole-Frenkel mechanism was observed with further increment in the temperature beyond 473 K. The temperature invariant dielectric tunability (nr ∼10%) and low zero electric field leakage current density (J ∼10−7A/cm2) at 673 K temperature, demonstrates the feasibility of nc-SiCN thin films for tunable device applications in the high-temperature and harsh environment.
      Graphical abstract image

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2017.10.017
  • Electronic transport study of PbSe pellets prepared from self-assembled
           2D-PbSe nanostructures
    • Authors: E. Díaz-Torres; A. Flores-Conde; A. Ávila-García; M. Ortega-López
      Pages: 226 - 230
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): E. Díaz-Torres, A. Flores-Conde, A. Ávila-García, M. Ortega-López
      This work presents a study of the electronic transport properties of PbSe pellets fabricated starting of PbSe nanostructures that exhibited a flake-like 2D morphology, which were synthesized by the co-precipitation method. Seebeck coefficient measurements revealed that the PbSe sample displays n-type conductivity, a maximum Seebeck coefficient of −512.6 μV/K around 380 K, and that the carriers scattering is dominated by acoustic and optical phonons. The Fermi level dependence on the temperature and the band gap energy are also reported. Interestingly, size-dependent confinement effects due probably to the reminiscent PbSe 2D character could be evidenced.

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2017.11.002
  • High efficiency screen-printed n-type silicon solar cell using
           co-diffusion of APCVD boron emitter and POCl3 back surface field
    • Authors: Kyungsun Ryu; Keeya Madani; Ajeet Rohatgi; Young-Woo Ok
      Pages: 231 - 235
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Kyungsun Ryu, Keeya Madani, Ajeet Rohatgi, Young-Woo Ok
      We present the fabrication and analysis of Passivated Emitter and Rear Totally Diffused (PERT) solar cells on n-type silicon using a co-diffusion process. In a single high temperature step, a BSG/SiOx stack deposited by APCVD and a POCl3 back surface field diffuse into the wafer to form the boron doped emitter and phosphorus doped back surface field. The SiOx layer on top of BSG acts as a masking layer to prevent cross-doping of phosphorus as well as a blocking layer for boron out-diffusion. This resulted in an initial sheet resistance of 76 Ω/□ with good uniformity and a final p+ emitter sheet resistance of 97 Ω/□ after boron rich layer removal. Additionally, bulk lifetime was investigated before and after the high temperature step that resulted in an increase from 1.2 ms to 1.5 ms due to a POCl3 gettering effect. A peak cell efficiency of 20.3% was achieved and each recombination component in terms of saturation current density was calculated and analyzed to understand the cell for further efficiency enhancement.

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2017.11.004
  • Micromagnetic study of domain wall depinning driven by nanosecond current
           pulse in notched Permalloy nanowires
    • Authors: Dede Djuhana; Candra Kurniawan; Dong-Hyun Kim
      Pages: 236 - 240
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Dede Djuhana, Candra Kurniawan, Dong-Hyun Kim
      The complete understanding of domain wall (DW) dynamics is important in the design of future spintronic devices. The characteristics of faster time-scale and lower current amplitude to move DW along nanowire are crucial in fabrication upgrade. In this study, we have investigated depinning behavior of magnetic domain wall triggered by nanosecond current pulse in notched Permalloy nanowires by means of micromagnetic simulation. We introduced double-triangular notch as the constrictions in the nanowire. The non-adiabaticity of the spin-transfer-torque is considered in simulation by varying the non-adiabatic constant (β) value. We observed that the depinning current density (J d) was not significantly affected by β for notch size (s) < 50 nm. Interestingly, we found that the depinning time (t d) for β ≥ 0.04 was slightly constant for all the cases with s > 70 nm, where the DW structure was kept to be a transverse structure during the depinning process. The broadly applicable depinning behavior is considered to contribute to the development of high-speed memory storage devices based on magnetic domain wall.

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2017.11.005
  • Effects of heating rate on the magneto-optical properties of
           bismuth-substituted yttrium iron garnet films prepared via modified
           metal-organic decomposition
    • Authors: Viet Dongquoc; Rambabu Kuchi; Phuoc Cao Van; Soon-Gil Yoon; Jong-Ryul Jeong
      Pages: 241 - 245
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Viet Dongquoc, Rambabu Kuchi, Phuoc Cao Van, Soon-Gil Yoon, Jong-Ryul Jeong
      This work investigated the effects of heating rate and annealing on the magneto-optical properties of bismuth-substituted yttrium iron garnet (Bi-YIG) thin films on glass and (111)-oriented single-crystalline gadolinium gallium garnet (GGG) substrates fabricated by metal-organic decomposition (MOD). We modified the MOD method by eliminating the pre-annealing process. We performed annealing at various temperatures to determine the optimal temperature for obtaining the Bi-YIG phase. We then annealed at the optimized temperature using various heating rates. The optimal conditions were annealing for 1 h at 750 °C at a heating rate of 30 °C/min on GGG to obtain highly crystallized fine grains. The Faraday rotation for this film was about −10.5°/μm. The optimized heating rate enhanced the magneto-optical properties due to improved crystallinity and saturated magnetization. The Bi-YIG thin films prepared by this prescribed MOD method exhibited excellent magneto-optical performance and are potential candidates for applications in optical devices.

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2017.11.006
  • Elucidating iron doping induced n- to p- characteristics of Strontium
           titanate based ethanol sensors
    • Authors: Neha Sarin; Monu Mishra; Govind Gupta; Ivan P. Parkin; Vandna Luthra
      Pages: 246 - 253
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Neha Sarin, Monu Mishra, Govind Gupta, Ivan P. Parkin, Vandna Luthra
      A series of pure and iron doped strontium titanate, (SrFexTi1-xO3; x = 0, 0.1 and 0.2) powders were synthesized, characterized and used to fabricate ethanol sensors for low concentration. X-Ray Diffraction (XRD) technique was used to confirm the single phase formation. Microstructural properties of the powders were investigated using scanning electron microscopy (SEM). Electrical conductivity of all the samples at room temperature (RT) was measured. Sensors were optimized for best responsiveness by varying the operating temperature from 350 °C to 500 °C.The sensor with doping x = 0.2 exhibited best sensing response at 400 °C for ethanol gas. The undoped sensor demonstrated a decrease in resistance on exposure to ethanol gas whereas Fe-doped sensors showed increase in resistance. The doping induced changeover from n to p behavior in the sensing response on doping has been investigated and corroborated with an observed shift in the Fermi level position by X-ray photoelectron spectroscopy (XPS). The disparity in gas sensing response clearly demonstrates inter-connection of multiple influencing factors such as electrical conductivity, morphology, porosity and change in chemical composition on doping. The sensors were exposed to ethanol, nitrogen dioxide, carbon monoxide, butane gases at concentration between 5 ppm and 50 ppm. The sensor exhibited much reduced relative response to all gases other than ethanol which can be utilized for wide range of applications.

      PubDate: 2018-01-10T07:07:39Z
      DOI: 10.1016/j.cap.2017.11.007
  • Chloride ion refined galvanic replacement: Boosting monodispersity of
           Au-Ag hollow nanoparticles & their enhanced applications
    • Authors: Kamalesh Nehra; P. Senthil Kumar
      Abstract: Publication date: Available online 21 February 2018
      Source:Current Applied Physics
      Author(s): Kamalesh Nehra, P. Senthil Kumar
      In this present work, we have redesigned the well-known Turkevich protocol for promoting versatile galvanic replacement, resulting in the synthesis of hollow Au nanostructures by the sacrificial reduction of HAuCl4 on the as-prepared Ag nanoparticles in the presence of slight excess NaCl in order to dictate their core size to cavity ratio in a highly reproducible manner. The significance of chloride ion interaction in tuning the size/shape control was corroborated with the contrasting effect of other halide ions, namely bromine and iodine. The structure-property functional relationship of these artificial hollow metal nanostructures were not only established using the systematic optical absorption and TEM measurements, but also through enhanced spectroscopy measurements such as SEIRA and SERS, elucidating the dynamic advantage of hollow nanostructures over and above their solid monometallic counterparts. Further, the familiar 4-NA to p-PDA catalytic reduction kinetics demonstrate the unusual zeroth order characteristics in the presence of hollow metal nanostructures, unequivocally distinguishing it from the common first order characteristics associated with the corresponding solid metal nanoparticles, essentially attributed to the morphology tuned accessible higher total surface area, thus exemplifying the aesthetic compliance for future technological applications.
      Graphical abstract image

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.009
  • Influence of MoS2 deposition time on the photocatalytic activity of MoS2/
           V, N co-doped TiO2 heterostructure thin film in the visible light region
    • Authors: Hang Nguyen Thai Phung; Nguyen Duc Truong; Phuong Ai Duong; Le Vu Tuan Hung
      Abstract: Publication date: Available online 17 February 2018
      Source:Current Applied Physics
      Author(s): Hang Nguyen Thai Phung, Nguyen Duc Truong, Phuong Ai Duong, Hung Vu Tuan Le
      Electron-hole separation and a narrow band-gap are essential steps to obtain efficient photocatalysis, towards which the use of co-catalysts or co-doped-TiO2 photocatalysts has become a widely used strategy. In this article, the combination of MoS2 and co-doping of V, N is the goal to achieve high performance photocatalysts. We synthesized MoS2/V, N co-doped TiO2 heterostructure thin film by sol-gel and chemical bath deposition methods. Herein, we investigated the influence of deposition time of MoS2 layer on visible-photocatalytic activity of the obtained samples. The thin films were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–vis spectroscopy techniques. Visible-photocatalytic activity of these samples were evaluated on the removal of methylene blue (MB) under visible light irradiation. The results show that the aforementioned heterostructure thin films have better photocatalytic activities than those of TiO2, MoS2 and V, N co-doped TiO2 counterparts in visible light region. The mechanism for increasing visible-photocatalytic property of the heterostructure thin films is discussed in detail. We find that MoS2/V, N co-doped TiO2 heterostructure thin film at MoS2 deposition time of 45-min shows the highest photocatalytic performance in the visible light region with MB photodegradation rate about 99% for 150 min and the degradation rate constant is 2.06 times higher than that of V and N co-doped TiO2 counterpart.
      Graphical abstract image

      PubDate: 2018-02-26T06:52:48Z
      DOI: 10.1016/j.cap.2018.02.004
  • Formation of graphene on amorphous SiC film by surface-confined heating
           with electron beam irradiation
    • Authors: Hanbyul Jin; Jung-Yong Lee Junhyung Kim Sungchul Jung Kyuhyung Kibog
      Abstract: Publication date: Available online 29 December 2017
      Source:Current Applied Physics
      Author(s): Hanbyul Jin, Jung-Yong Lee, Junhyung Kim, Sungchul Jung, Kyuhyung Mo, Kibog Park
      It is demonstrated experimentally that graphene can form on the surface of an amorphous SiC film by irradiating electron beam (e-beam) at low acceleration voltage. As the electron irradiation fluency increases, the crystallinity and uniformity of graphene improve, which is confirmed by the changes of the measured Raman spectra and secondary electron microscopy images. Due to the shallow penetration depth of e-beam with low acceleration voltage, only the region near the surface of SiC film will be heated by the thermalization of irradiated electrons with multiple scattering processes. The thermalized electrons are expected to weaken the bond strength between Si and C atoms so that the thermal agitation required for triggering the sublimation of Si atoms decreases. With these assistances of irradiated electrons, it is considered that graphene can grow on the surface of SiC film at temperature reduced substantially in comparison with the conventional vacuum annealing process.

      PubDate: 2018-01-10T07:07:39Z
  • Effect of adding non-ferromagnetic nanoparticles to grain boundary on
           coercivity of sintered Nd-Fe-B magnet
    • Authors: Pham Thi; Thanh Nguyen Van Duong Nguyen Hai Yen Nguyen
      Abstract: Publication date: Available online 27 December 2017
      Source:Current Applied Physics
      Author(s): Pham Thi Thanh, Nguyen Van Duong, Nguyen Hai Yen, Nguyen Huy Ngoc, Nguyen Mau Lam, Kieu Xuan Hau, Seong Cho Yu, Nguyen Huy Dan
      In this work, we investigated the influence of additional compounds of Nd-Cu-Al, Dy-Nb-Al, Dy-Zr-Al and Nb-Cu-Al on coercivity of sintered Nd-Fe-B magnets. The additional nanoparticles with size in the range of 40–80 nm was mixed with the micrometer Nd-Fe-B powder before sintering process. The results show that the coercivity of the sintered Nd-Fe-B magnets can be improved by introducing additional nanoparticles to their grain boundaries. The improvement of the coercivity of the magnets is clearly dependent on composition and fraction of the additional compounds. While the Dy-Nb-Al, Dy-Zr-Al and Nb-Cu-Al compounds degrade the coercivity of the sintered Nd-Fe-B magnets, the Nd-Cu-Al nanoparticles considerably improve this quantity. The coercivity the sintered Nd16.5Fe77B6.5 magnets has been enhanced about 40% by adding 3 wt% of the Dy-free compound of Nd40Cu30Al30.

      PubDate: 2018-01-10T07:07:39Z
  • Potential of metal–fullerene hybrids as strong nanocarriers for cytosine
           and guanine nucleobases: A detailed DFT study
    • Authors: Ali Shokuhi Rad; Sadegh Mehdi Aghaei
      Pages: 133 - 140
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Ali Shokuhi Rad, Sadegh Mehdi Aghaei
      In this article, the adsorption of cytosine and guanine molecules on the surface of Cr-doped C20 fullerene (C19Cr) and Ni-doped C20 fullerene (C19Ni) are studied using first-principles density functional theory (DFT) calculations. In order to thoroughly comprehend the influences of the molecules on the metal-fullerene complexes, the geometric parameters, the binding energies, transferred charges, the magnitude of dipole moments, thermochemical parameters, frontier molecular orbitals, and the global indices of activities are calculated. The results highlighted that the interactions of both cytosine and guanine molecules with metal-fullerene complexes are highly exothermic, suggesting that these molecules might be chemisorbed on their adsorbents. The C19Cr exhibits a better adsorption behavior toward the molecules compared to C19Ni, and cytosine has the higher binding energies with metal-fullerene complexes in comparison with guanine. Further analyses showed that the C19Cr experiences significant changes in its electronic properties upon adsorption of the cytosine molecule. However, the small variations in the electronic properties of C19Ni after complexation with guanine indicate that this complex is not sensitive to the guanine. Furthermore, the results of frontier molecular orbital reveal the strong (moderate) interactions between the C19Cr with the cytosine (guanine) molecule and moderate (weak) interactions between the C19Ni with the cytosine (guanine) molecule. Therefore, the C19Cr and C19Ni have moderate sensitivities to cytosine and guanine molecules. More excitingly, our findings divulge promising potential of the Cr-fullerene complex as a biochemical adsorbent for cytosine.
      Graphical abstract image

      PubDate: 2017-12-27T06:12:27Z
      DOI: 10.1016/j.cap.2017.11.016
  • Ultrasmall iron oxide nanoparticles: Magnetic and NMR relaxometric
    • Authors: Branka Babić-Stojić; Vukoman Jokanović; Dušan Milivojević; Miroslav Požek; Zvonko Jagličić; Darko Makovec; Nataša Jović Orsini; Mirjana Marković; Katarina Arsikin; Verica Paunović
      Pages: 141 - 149
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Branka Babić-Stojić, Vukoman Jokanović, Dušan Milivojević, Miroslav Požek, Zvonko Jagličić, Darko Makovec, Nataša Jović Orsini, Mirjana Marković, Katarina Arsikin, Verica Paunović
      Ultrasmall iron oxide (USPIO) nanoparticles, with diameter mostly less than 3 nm dispersed in an organic carrier fluid were synthesized by polyol route. The evolution of ZFC-FC magnetization curves with temperature, as well as the shift of the ac susceptibility peaks upon changing the frequency, reveal that the nanoparticles in the fluid are non-interacting and superparamagnetic with the blocking temperature T B ∼10 K. The Mössbauer spectra analysis proposed the core/shell structure of the nanoparticles consisting of stoichiometric γ-Fe2O3 core and non-stoichiometric shell. The nanoparticle surface layer has a great influence on their properties which is principally manifested in significant reduction of the magnetization and in a large increase in magnetic anisotropy. Magnetic moments do not saturate in fields up to 5 T, even at the lowest measured temperature, T = 5 K. The average magnetic particle diameter is changed from 1.3 to 1.8 nm with increasing magnetic field from 0 to 5 T which is noticeably smaller than the particle sizes measured by TEM. The estimated effective magnetic anisotropy constant value, K eff = 2 × 105 J/m3, is two orders of magnitude higher than in the bulk maghemite. Measurements of the longitudinal and transverse NMR relaxivity parameters on water diluted nanoparticle dispersions at 1.5 T gave the values r 1 = 0.028 mmol−1 s−1, r 2 = 0.050 mmol−1 s−1 and their ratio r 2/r 1 = 1.8. Continuous increase of the T 1-weighted MRI signal intensity with increasing Fe concentration in the nanoparticle dispersions was observed which makes this ferrofluid to behave as a positive T 1 contrast agent.

      PubDate: 2017-12-27T06:12:27Z
      DOI: 10.1016/j.cap.2017.11.017
  • Electronic structure and magnetic properties of BaTi1-xMnxO3
    • Authors: N.V. Dang; N.T. Dang; T.A. Ho; N. Tran; T.L. Phan
      Pages: 150 - 154
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): N.V. Dang, N.T. Dang, T.A. Ho, N. Tran, T.L. Phan
      The electronic structure and magnetic properties of polycrystalline BaTi1-xMnxO3 (x = 0–0.1) compounds prepared by solid-state reactions were studied. The results revealed that the increase in Mn content (x) did not change the oxidation numbers of Ba (+2) and Ti (+4) in BaTi1-xMnxO3. However, there is the change in Mn valence that Mn3+,4+ ions coexist in the samples with x = 0.01–0.04 while Mn4+ ions are almost dominant in the samples with x = 0.06–0.1. We also point out that Mn3+ and Mn4+ ions substitute for Ti4+ and prefer locating in the tetragonal and hexagonal BaTiO3 structures, respectively, in which the hexagonal phase constitutes soon as x = 0.01. Particularly, all the samples exhibit room-temperature ferromagnetism. Ferromagnetic order increases with increasing x from 0 to 0.02, but decreases as x ≥ 0.04. We think that ferromagnetism in BaTi1-xMnxO3 is related to lattice defects and/or exchange interactions between Mn3+ and Mn4+ ions.

      PubDate: 2017-12-27T06:12:27Z
      DOI: 10.1016/j.cap.2017.11.020
  • Effect of transition metal oxidation state on crystal structure and
           magnetic ordering in frustrated ABaM4O7 systems (A= Y, Ca; M= Co, Fe):
           X-ray diffraction, soft X-ray absorption, and magnetization studies
    • Authors: V.R. Galakhov; D.I. Turkin; V.V. Mesilov; S.N. Shamin; G.V. Bazuev; K. Kuepper
      Pages: 155 - 162
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): V.R. Galakhov, D.I. Turkin, V.V. Mesilov, S.N. Shamin, G.V. Bazuev, K. Kuepper
      We present X-ray diffraction patterns, soft Ca, Co, and Fe L 2,3 absorption spectra, magnetic susceptibility, and temperature dependent magnetization measurements in order to characterize ABaM 4O7 solid solutions A = Y, Ca; M = Co, Fe). Cobalt ions are in 2 + and high-spin 3 + oxidation states. In the iron-doped solid solutions, Fe ions were found to be trivalent. Doping with Fe ions leads to a decreasing amount of Co3+ ions. Magnetic properties of the studied samples showed a spin-glass behavior. Negative values of the Curie–Weiss temperatures indicated the predominance of antiferromagnetic exchange interactions. The freezing point of the magnetic moments is 51 K and does not vary with the amount of Fe doping.
      Graphical abstract image

      PubDate: 2017-12-27T06:12:27Z
      DOI: 10.1016/j.cap.2017.11.019
  • Synthesis and characterization of nitrogen-doped TiO2 coatings on reduced
           graphene oxide for enhancing the visible light photocatalytic activity
    • Authors: Yifan Zhang; Hye Mee Yang; Soo-Jin Park
      Pages: 163 - 169
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Yifan Zhang, Hye Mee Yang, Soo-Jin Park
      Nitrogen-doped TiO2 coatings on reduced graphene oxide were prepared via a sonochemical synthesis and hydrothermal process. The nanocomposites showed improved photocatalytic activity due to their large specific surface areas (185–447 m2/g), the presence of TiO2 in the anatase phase, and a quenched photoluminescence peak. In particular, GN3-TiO2 (nitrogen-doped TiO2 coatings on rGO with 3 ml of titanium (IV) isopropoxide) exhibited the best photocatalytic efficiency and degradation rate among the materials prepared. With nitrogen-doped on the reduced graphene oxide surface, the photocatalytic activity is enhanced approximately 17.8 times compared to that of the pristine TiO2. The dramatic enhancement of activity is attributed to the nitrogen contents and rGO effectively promoting charge-separation efficiency and providing abundant catalytically active sites to enhance the reactivity. The composites also showed improved pollutant adsorption capacity, electron–hole pair lifetime, light absorption capability, and absorbance of visible light.
      Graphical abstract image

      PubDate: 2017-12-27T06:12:27Z
      DOI: 10.1016/j.cap.2017.12.001
  • Electronic structure of the PLD grown mixed phase MoS2/GaN interface and
           its thermal annealing effect
    • Authors: Arun Barvat; Nisha Prakash; Gaurav Kumar; Dilip K. Singh; Anjana Dogra; Suraj P. Khanna; Prabir Pal
      Pages: 170 - 177
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Arun Barvat, Nisha Prakash, Gaurav Kumar, Dilip K. Singh, Anjana Dogra, Suraj P. Khanna, Prabir Pal
      We report the electronic structure of Molybdenum disulfide (MoS2) ultrathin 2D films grown by pulsed laser deposition (PLD) on top of GaN/c-Al2O3 (0001) substrates annealed up to 550 °C in an ultrahigh vacuum. Our X-ray photoemission spectroscopy (XPS) study shows that the grown films are mixed phase character with semiconducting 2H and metallic 1T phases. After ultrahigh vacuum (UHV) annealing, the 1T/2H phase ratio is significantly modified and film-substrate bonding becomes the leading factor influencing variation of mixed phase compositions. The semiconducting phase is partially transformed to metallic phase by thermal annealing; suggesting that the metallic phase observed here may indeed have more stability compared to the semiconducting phase. The notable enhancement of the 1T/2H ratio induces significant changes in Ga 3d core level spectra taken from bare GaN and MoS2/GaN sample. The impact of S and/or Mo atoms on the Ga core level spectra is further pronounced with the thermal annealing of grown films. The analysis shows that an enhancement of 1T metallic phase with thermal annealing in MoS2 layers is manifested by the occurrence of new spectral component in the Ga 3d core level spectra with the formation of Ga-S adlayer interaction through the Ga bonding in defect assisted GaN structure.

      PubDate: 2017-12-27T06:12:27Z
      DOI: 10.1016/j.cap.2017.12.002
  • Efficient implementation of multiple drive-in steps in thermal diffusion
           of phosphorus for PERC solar cells
    • Authors: Dongchul Suh
      Pages: 178 - 182
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Dongchul Suh
      N-type phosphorus diffusion in silicon using phosphorus oxychloride, POCl3, has been widely used in the production of p-type silicon solar cells. The thermal diffusion process in a furnace generally involves two steps: pre-deposition and drive-in. The phosphorous doping by thermal diffusion often shows high surface concentrations, leading to an increase in charge recombination, which should be inhibited in order to fabricate high efficiency silicon solar cells. In this study, we investigate the influence of 3 drive-in steps at sequentially increasing temperatures during the POCl3 diffusion on the emitter performance. As a result, it was found that the kink region was made shorter while maintaining surface concentration for a good metal contact without losing its passivation quality. This result is attributed to the higher active dopant concentration of the 3 drive-in step samples, leading to a lower series resistance and higher fill factor in the PERC solar cells. The results show that slight changes in the PSG process conditions can contribute to the improvement of high efficiency solar cells.

      PubDate: 2017-12-27T06:12:27Z
      DOI: 10.1016/j.cap.2017.11.024
  • Investigation of the interstitial oxygen behaviors in vanadium alloy: A
           first-principles study
    • Authors: Xingming Zhang; Yifan Li; Qiaoling He; Ruilian Li; Lei Deng; Liang Wang; Xunlin Liu; Jianfeng Tang; Huiqiu Deng; Wangyu Hu
      Pages: 183 - 190
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Xingming Zhang, Yifan Li, Qiaoling He, Ruilian Li, Lei Deng, Liang Wang, Xunlin Liu, Jianfeng Tang, Huiqiu Deng, Wangyu Hu
      This study aims at characterizing the interstitial Oxygen (O) behaviors in the Vanadium (V) Alloy by means of the first-principles calculations. For this, the interations between vacancy (Vac) and O interstitil atom are studied in detail to obtain the binding energies and stable structures of the complexes. It can be seen that monovacancy binding with two O atoms occupied the opposing octahedral stie are particularly stable, and is liable to form VacO2 cluster in the V alloys. According to the mass action analysis, the predicted temperature dependence of the concentration for VacO n complexes are presented. Apart from monovacancy, we also consider the trapping behavior of vacancy cluster on the O atoms. The results also prove that one vacancy can trap two O atoms in the V alloys. Based the diffusion theory, we obtain the diffusion coefficients as a function of temperature with or without the vacancy effect in the V alloys. The predicted O diffusion coefficients in defect-free V alloys from our first-principles calculations are in excellent ageement with the experimental data, meanings that the vacancy-limited mechanism does not play the key role for O diffusion in V alloys. Regarding the interactions between vacancy, solutes and O atom, combining with the diffusion barriers of O affected by vacancy and solute, we infer the formation mechanism of the precipitates in the V alloys.

      PubDate: 2017-12-27T06:12:27Z
      DOI: 10.1016/j.cap.2017.12.003
  • Characterization of CBO and defect states of CZTSe solar cells prepared by
           using two-step process
    • Authors: SeongYeon Kim; JunHo Kim; Tanka R. Rana; Kang-Woo Kim; Myeung-Hoi Kwon
      Pages: 191 - 199
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): SeongYeon Kim, JunHo Kim, Tanka R. Rana, Kang-Woo Kim, Myeung-Hoi Kwon
      We fabricated kesterite Cu2ZnSnSe4 (CZTSe) solar cells and studied device characteristics, where CZTSe absorbers were made by using two-step process. First, we deposited precursor CZTSe films with spin-coating or sputtering, and performed sulfurization and subsequent selenization. To complete the device, we applied In2S3 as a buffer layer. We obtained power conversion efficiency (PCE) of 4.18% with spin-coated CZTSe absorber and 5.60% with sputtered CZTSe absorber. Both devices showed deep defects in the bulk and strong interface recombinations near the pn junction. In addition, we observed red-kinks in the current density-voltage (J-V) curves for both devices under the filtered light illumination (>660 nm), which is attributed to large conduction band offset (CBO) between the CZTSe absorber and the buffer layer and defect states in the buffer/CZTSe absorber or in the buffer. The red-kink was also observed in CZTSe (PCE of 7.76%) solar cell with CdS buffer. Hence, to enhance the PCE with CZTSe absorber, along with suppression of deep defects which act as recombination center, optimization of CBO between absorber and buffer is also required.

      PubDate: 2017-12-27T06:12:27Z
      DOI: 10.1016/j.cap.2017.12.004
  • First-principles study on the electronic structure and optical properties
           of La0.75Sr0.25MnO3-σ materials with oxygen vacancies defects
    • Authors: Jun Jiang; Qing-Ming Chen; Xiang Liu
      Pages: 200 - 208
      Abstract: Publication date: February 2018
      Source:Current Applied Physics, Volume 18, Issue 2
      Author(s): Jun Jiang, Qing-Ming Chen, Xiang Liu
      The electronic structure and optical properties of La0.75Sr0.25MnO3-σ (LSMO3-σ ) materials with 1 × 1 × 4 orthorhombic perovskite structure were performed by first-principles calculation. The structural changing of LSMO3 (ideal structure, σ = 0) was not obvious under generalized gradient approximation (GGA) and GGA + U arithmetic. On the contrary, the structural changing of LSMO3-σ (σ = 0.25, with oxygen vacancies defects in the z = 0, c/8, c/6, c/4, and c/2) with GGA + U were more obvious than the result of ideal. This structural distortion induced distinct changing in density of states (DOS) for LSMO3-σ materials. Oxygen vacancy defects caused a shift of the total density of states (TDOS) features toward low binding energies and LSMO3-σ keep half-metal properties as well as LSMO3 ideal structure. In addition, the hybridization between the Mn-e g and O-2p orbital was weakened and the partial density of states (PDOS) of Mn indicated a strong d-d orbital interaction. By the result of oxygen vacancy formation energy, oxygen vacancy defects can be more easily formed in La-O layers (z = 0 and c/6) to compare with other layers (z = c/8, c/4 and c/2). The calculation result of optical properties suggested that the ideal LSMO could be produced strong absorption in the range of ultraviolet and visible light, while the LSMO3-σ with oxygen vacancies defects were presented weak absorption in the range of visible light.

      PubDate: 2017-12-27T06:12:27Z
      DOI: 10.1016/j.cap.2017.12.005
  • Performance of ring oscillators composed of gate-all-around FETs with
           varying numbers of nanowire channels using TCAD simulation
    • Authors: Sutae Kim; Minsuk Kim Sola Woo Hyungu Kang Sangsig Kim
      Abstract: Publication date: Available online 22 December 2017
      Source:Current Applied Physics
      Author(s): Sutae Kim, Minsuk Kim, Sola Woo, Hyungu Kang, Sangsig Kim
      In this paper, we investigate the performance of ring oscillators composed of gate-all-around (GAA) silicon nanowire (NW) field-effect transistors (FETs) with four different numbers of NW channels, for sub-10-nm logic applications. Our simulations reveal that ring oscillators with double, triple, and quadruple NW channels exhibit improvements of up to 50%, 85%, and 97%, respectively, in the oscillation frequencies (f osc ), compared to a ring oscillator with a single NW channel, due to the large drive current, in spite of the increased intrinsic capacitance of a given device. Moreover, our work shows that the f osc improvement ratio of the ring oscillators becomes saturated with triple NW channels with additional load capacitances of 0.1 fF and 0.01 fF, which are similar to, or less than the intrinsic device capacitance (∼0.1 fF). Thus, our study provides an insight for determining the capacitive load and optimal number of NW channels, for device development and circuit design of GAA NW FETs.

      PubDate: 2017-12-27T06:12:27Z
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