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Sample records for nano structured thin

  1. Preface: Advanced Thin Film Developments and Nano Structures

    Institute of Scientific and Technical Information of China (English)

    Ray Y.Lin

    2005-01-01

    @@ In this special issue, we invited a few leading materials researchers to present topics in thin films, coatings, and nano structures. Readers will find most recent developments in topics, including recent advances in hard, tough, and low friction nanocomposite coatings; thin films for coating nanomaterials; electroless plating of silver thin films on porous Al2O3 substrate; CrN/Nano Cr interlayer coatings; nano-structured carbide derived carbon (CDC) films and their tribology; predicting interdiffusion in high-temperature coatings; gallium-catalyzed silica nanowire growth; and corrosion protection properties of organofunctional silanes. Authors are from both national laboratories and academia.

  2. Nano-structural characteristics and optical properties of silver chiral nano-flower sculptured thin films

    Science.gov (United States)

    Savaloni, Hadi; Haydari-Nasab, Fatemh; Malmir, Mariam

    2011-08-01

    Silver chiral nano-flowers with 3-, 4- and 5-fold symmetry were produced using oblique angle deposition method in conjunction with the rotation of sample holder with different speeds at different sectors of each revolution corresponding to symmetry order of the acquired nano-flower. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), were employed to obtain morphology and nano-structure of the films. Optical characteristics of silver chiral nano-flower thin films were obtained using single beam spectrophotometer with both s- and p-polarization incident light at 30° and 70° incidence angles and at different azimuthal angles ( φ). Optical spectra showed both TM (TDM (transverse dipole mode) and TQM (transverse quadruple mode)) and LM (longitudinal mode) Plasmon resonance peaks. For 3- and 4-fold symmetry chiral nano-flowers the s-polarization extinction spectra obtained at different azimuthal angles did not show significant change in the Plasmon peak position while 5-fold symmetry chiral nano-flower showed a completely different behavior, which may be the result of increased surface anisotropy, so when the φ angle is changed the s-polarization response from the surface can change more significantly than that for lower symmetries. In general, for 3-, 4- and 5-fold symmetry chiral nano-flowers a sharp peak at lower wavelengths (<450 nm) is observed in the s-polarization spectra, while in addition to this peak a broad peak at longer wavelengths (i.e., LM) observed in the p-polarization spectra, which is more dominant for 70° incidence angle.

  3. Nano-structural characteristics and optical properties of silver chiral nano-flower sculptured thin films

    Energy Technology Data Exchange (ETDEWEB)

    Savaloni, Hadi, E-mail: savaloni@khayam.ut.ac.ir [Department of Physics, University of Tehran, North-Kargar Street, Tehran (Iran, Islamic Republic of); Haydari-Nasab, Fatemh; Malmir, Mariam [Department of Physics, University of Tehran, North-Kargar Street, Tehran (Iran, Islamic Republic of)

    2011-08-15

    Silver chiral nano-flowers with 3-, 4- and 5-fold symmetry were produced using oblique angle deposition method in conjunction with the rotation of sample holder with different speeds at different sectors of each revolution corresponding to symmetry order of the acquired nano-flower. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), were employed to obtain morphology and nano-structure of the films. Optical characteristics of silver chiral nano-flower thin films were obtained using single beam spectrophotometer with both s- and p-polarization incident light at 30{sup o} and 70{sup o} incidence angles and at different azimuthal angles ({phi}). Optical spectra showed both TM (TDM (transverse dipole mode) and TQM (transverse quadruple mode)) and LM (longitudinal mode) Plasmon resonance peaks. For 3- and 4-fold symmetry chiral nano-flowers the s-polarization extinction spectra obtained at different azimuthal angles did not show significant change in the Plasmon peak position while 5-fold symmetry chiral nano-flower showed a completely different behavior, which may be the result of increased surface anisotropy, so when the {phi} angle is changed the s-polarization response from the surface can change more significantly than that for lower symmetries. In general, for 3-, 4- and 5-fold symmetry chiral nano-flowers a sharp peak at lower wavelengths (<450 nm) is observed in the s-polarization spectra, while in addition to this peak a broad peak at longer wavelengths (i.e., LM) observed in the p-polarization spectra, which is more dominant for 70{sup o} incidence angle.

  4. Structural and Optical Study of Chemical Bath Deposited Nano-Structured CdS Thin Films

    Science.gov (United States)

    Kumar, Suresh; Sharma, Dheeraj; Sharma, Pankaj; Sharma, Vineet; Barman, P. B.; Katyal, S. C.

    2011-12-01

    CdS is commonly used as window layer in polycrystalline solar cells. The paper presents a structural and optical study of CdS nano-structured thin films. High quality CdS thin films are grown on commercial glass by means of chemical bath deposition. It involves an alkaline solution of cadmium salt, a complexant, a chalcogen source and a non-ionic surfactant. The films have been prepared under various process parameters. The chemically deposited films are annealed to estimate its effect on the structural and optical properties of films. These films (as -deposited and annealed) have been characterized by means of XRD, SEM and UV-Visible spectrophotometer. XRD of films show the nano-crystalline nature. The energy gap of films is found to be of direct in nature.

  5. Preparation and Characterization of Nano-Structured SiO2 Thin Films on Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    Rong Chun XIONG; Dong Zhou YAN; Gang WEI

    2003-01-01

    Nano-structured SiO2 thin films were prepared on the surface of carbon steel for the first time by LPD. The compositions of the films were analyzed by XPS, and the surface morphology of the thin films were observed by AFM. The thin films were constituted by compact particles of SiO2, and there was no Fe in the films. In the process of film forming, the SiO2 colloid particles were deposited or absorbed directly onto the surface of carbon steel substrates that were activated by acid solution containing inhibitor, and corrosion of the substrates was avoided. The nano-structured SiO2 thin films that were prepared had excellent protective efficiency to the carbon steel.

  6. Broadband light-trapping in ultra-thin nano-structured solar cells

    Science.gov (United States)

    Colin, Clément; Massiot, Inès.; Cattoni, Andrea; Vandamme, Nicolas; Dupuis, Christophe; Bardou, Nathalie; Gerard, Isabelle; Naghavi, Negar; Guillemoles, Jean-François; Pelouard, Jean-Luc; Collin, Stéphane

    2013-03-01

    Conventional light trapping techniques are inefficient at the sub-wavelength scale. This is the main limitation for the thickness reduction of thin-film solar cells below 500nm. We propose a novel architecture for broadband light absorption in ultra-thin active layers based on plasmonic nano-cavities and multi-resonant mechanism. Strong light enhancement will be shown numerically for photovoltaic materials such as CIGSe and GaAs. First experiments on ultrathin nano-patterned CIGSe solar cells will be presented.

  7. Effect of Al Doping on Structural, Electrical, Optical and Photoluminescence Properties of Nano-Structural ZnO Thin Films

    Institute of Scientific and Technical Information of China (English)

    M. Mozibur Rahman; M.K.R. Khan; M. Rafiqul Islam; M.A. Halim; M. Shahjahan; M.A. Hakim; Dilip Kumar Saha; Jasim Uddin Khan

    2012-01-01

    The nano-structural Al-doped ZnO thin films of different morphologies deposited on glass substrate were successfully fabricated at substrate temperature of 350 ℃ by an inexpensive spray pyrolysis method. The structural, electrical, optical and photoluminescence properties were investigated. X-ray diffraction study revealed the crystalline wurtzite (hexagonal) structure of the films with nano-grains. Scanning electron microscopy (SEM) micrographs indicated the formation of a large variety of nano-structures during film growth. The spectral absorption of the films occurred at the absorption edge of -410 nm. In the present study, the optical band gap energy 3.28 eV of ZnO decreased gradually to 3.05 eV for 4 mol% of AI doping. The deep level activation energy decreased and carrier concentrations increased substantially with increasing doping. Exciting with the energy 3.543 eV (A=350 nm), a narrow and a broad characteristic photoluminescence peaks that correspond to the near band edge (NBE) and deep level emissions (DLE), respectively emerged.

  8. Experiment and prediction on thermal conductivity of Al2O3/ZnO nano thin film interface structure

    Indian Academy of Sciences (India)

    Ping Yang; Liqiang Zhang; Haiying Yang; Dongjing Liu; Xialong Li

    2014-05-01

    We predict that there is a critical value of Al2O3/ZnO nano thin interface thickness based on two assumptions according to an interesting phenomenon, which the thermal conductivity (TC) trend of Al2O3/ZnO nano thin interface is consistent with that of relevant single nano thin interface when the nano thin interface thickness is > 300 nm; however, TC of Al2O3/ZnO nano thin interface is higher than that of relevant single nano thin interface when the thin films thickness is < 10 nm. This prediction may build a basis for the understanding of interface between two different oxide materials. It implies an idea for new generation of semiconductor devices manufacturing.

  9. Process nano scale mechanical properties measurement of thin metal films using a novel paddle cantilever test structure

    CERN Document Server

    Tong, Chi-Jia

    2008-01-01

    A new technique was developed for studying the mechanical behavior of nano-scale thin metal films on substrate is presented. The test structure was designed on a novel "paddle" cantilever beam specimens with dimensions as few hundred nanometers to less than 10 nanometers. This beam is in triangle shape in order to provide uniform plane strain distribution. Standard clean room processing was used to prepare the paddle sample. The experiment can be operated by using the electrostatic deflection on the paddle uniform distributed stress cantilever beam and then measure the deposited thin metal film materials on top of it. A capacitance technique was used to measurement on the other side of the deflected plate to measure its deflection with respect to the force. The measured strain was converted through the capacitance measurement for the deflection of the cantilever. System performance on the residual stress measurement of thin films are calculated with three different forces on the "paddle" cantilever beam, incl...

  10. Nano-structure and optical properties (plasmonic) of graded helical square tower-like (terraced) Mn sculptured thin films

    Science.gov (United States)

    Savaloni, Hadi; Fakharpour, Mahsa; Siabi-Garjan, Araz; Placido, Frank; Babaei, Ferydon

    2017-01-01

    Graded helical square tower-like terraced sculptured Mn thin films (GHSTTS) are produced in three stages with different number of arms using oblique angle deposition together with rotation of substrate holder about its surface normal, plus a shadowing block fixed at the centre of the substrate holder. The structural characterization of the produced samples was obtained using field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). Results showed a structural gradient with distance from the edge of the shadowing block, which in turn is responsible for the decrease in the volume of void fraction and increase of grain size. Plasmon absorption peaks observed in the optical analysis of these nano-structures showed that their wavelength region and intensity depend on the polarization and the incident angle of light, as well as the distance from the edge of the shadowing block. According to our model and discrete dipole approximation (DDA) calculations, when the number of parallel nano-rods of different lengths and radii are increased the peak in the spectrum shifts to shorter wavelengths (blue shift). Also when the diameters of the nano-rods increases (a situation that occurs with increasing film thickness) the results is again a blue shift in the spectrum. The presence of defects in these sculptured structures caused by the shadowing effect is predicted by the theoretical DDA investigation of their optical spectra. Good agreement is obtained between our theoretical results and the experimental observations in this work.

  11. Synthesis and characterization of DC magnetron sputtered nano structured molybdenum thin films

    Science.gov (United States)

    Rondiya, S. R.; Rokade, A. V.; Jadhavar, A. A.; Pandharkar, S. M.; Kulkarni, R. R.; Karpe, S. D.; Diwate, K. D.; Jadkar, S. R.

    2016-04-01

    Molybdenum (Mo) thin films were deposited on corning glass (#7059) substrates using DC magnetron sputtering system. The effect of substrate temperature on the structural, morphology and topological properties have been investigated. Films were characterized by variety of techniques such as low angle x-ray diffraction (low angle XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM). The low angle XRD analysis revealed that the synthesized Mo films are nanocrystalline having cubic crystal structure with (110) preferential orientation. The microstructure of the deposited Mo thin films observed with FE-SEM images indicated that films are homogeneous and uniform with randomly oriented leaf shape morphology. The AFM analysis shows that with increase in substrate temperature the rms roughness of Mo films increases. The obtained results suggest that the synthesized nanostructured Mo thin films have potential application as a back contact material for high efficiency solar cells like CdTe, CIGS, CZTS etc.

  12. Effective Light Trapping in Thin Film Silicon Solar Cells with Nano- and Microscale Structures on Glass Substrate.

    Science.gov (United States)

    Bong, Sungjae; Ahn, Shihyun; Anh, Le Huy Tuan; Kim, Sunbo; Park, Hyeongsik; Shin, Chonghoon; Park, Jinjoo; Lee, Younjung; Yi, Junsin

    2016-05-01

    For thin film silicon-based solar cells, effective light trapping at a broad range of wavelengths (400-1100 nm) is necessary. Normally, etching is only carried out with TCOs, such as SnO2:F and impurity doped ZnO, to form nano-sized craters in the surface morphology to confer a light trapping effect. However, in this study, prior to ZnO:Al etching, periodic structures on the glass substrates were made by photolithography and wet etching to increase the light scattering and internal reflection. The use of periodic structures on the glass substrate resulted in higher haze ratios in the range from 550 nm to 1100 nm, which is the optical absorption wavelength region for thin film silicon solar cells, than obtained by simple ZnO:Al etching. The periodically textured glass with micro-sized structures compensates for the low haze ratio at the middle and long wavelengths of wet etched ZnO:Al. ZnO:Al was deposited on the periodically textured glass, after which the ZnO:Al surface was also etched randomly using a mixed acid solution to form nano-sized craters. The thin film silicon solar cells with 350-nm-thick amorphous silicon absorber layer deposited on the periodic structured glass and etched ZnO:Al generated up to 10.68% more photocurrent, with 11.2% increase of the conversion efficiency compared to the cell deposited on flat glass and etched ZnO:Al.

  13. Nano-structural Modification of Amorphous Carbon Thin Films by Low-energy Electron Beam Irradiation

    Institute of Scientific and Technical Information of China (English)

    EijiIwamura; MasanoriYamaguchi

    2004-01-01

    A new approach using a low-energy electron beam radiation system was investigated to synthesize carbon hybrid structures in amorphous carbon thin films. Two types of amorphous carbon films, which were 15at% iron containing film and with column/inter-column structures, were deposited onto Si substrates by a sputtering technique and subsequently exposed to an electron shower of which the energy and dose rate were much smaller compared to an intense electron beam used in a transmission electron microscopy. As a result of the low-energy and low-dose electron irradiation process, graphitic structures formed in amorphous matrix at a relatively low temperature up to 450 K. Hybrid carbon thin films containing onion-like structures in an amorphous carbon matrix were synthesized by dynamic structural modification of iron containing amorphous carbon thin films. It was found that the graphitization progressed more in the electron irradiation than in annealing at 773K, and it was attributed to thermal and catalytic effects which are strongly related to grain growth of metal clusters. On the other hand, a reversal of TEM image contrast was observed in a-C films with column/inter-column structures. It is presumed that preferable graphitization occurred in the inter-column regions induced by electron irradiation.

  14. Nano-structural Modification of Amorphous Carbon Thin Films by Low-energy Electron Beam Irradiation

    Institute of Scientific and Technical Information of China (English)

    Eiji Iwamura; Masanori Yamaguchi

    2004-01-01

    A new approach using a low-energy electron beam radiation system was investigated to synthesize carbon hybrid structures in amorphous carbon thin films. Two types of amorphous carbon films, which were 15at% iron containing film and with column/inter-column structures, were deposited onto Si substrates by a sputtering technique and subsequently exposed to an electron shower of which the energy and dose rate were much smaller compared to an intense electron beam used in a transmission electron microscopy. As a result of the low-energy and low-dose electron irradiation process,graphitic structures formed in amorphous matrix at a relatively low temperature up to 450 K. Hybrid carbon thin films containing onion-like structures in an amorphous carbon matrix were synthesized by dynamic structural modification of iron containing amorphous carbon thin films. It was found that the graphitization progressed more in the electron irradiation than in annealing at 773K, and it was attributed to thermal and catalytic effects which are strongly related to grain growth of metal clusters. On the other hand, a reversal of TEM image contrast was observed in a-C films with column/inter-column structures. It is presumed that preferable graphitization occurred in the inter-column regions induced by electron irradiation.

  15. Tunneling Magneto-resistance in grain boundary tailored Fe3O4 nano structured thin films

    Science.gov (United States)

    Kumar, Ankit; Behera, Nilamani; Husain, Sajid; Chaudhary, Sujeet; Pandya, Dinesh K.

    2017-05-01

    The pulse DC sputtered nanostructured Fe3O4 thin films have been subjected to hydrocarbon treatment and vacuum annealing to investigate their effect on grain boundaries. Remarkably, this treatment causes a change in the crystallographic structure of the film from polycrystalline to (440) oriented one and enhancement in film conductivity. Hopping conduction mechanism changes to nearest-neighbor hoping above Verwey transition temperature of 110 K on treatment. Treatment also leads to grain boundary modification by incorporation of antiferro defects that inhibit an increase in MR despite enhanced electron conduction across grain boundaries. Our results follow the non-homogeneous grain boundary model.

  16. Structure Analysis and Optical Parameters of Nano-scale ZnSe/Flexible Substrate Thin Film

    Science.gov (United States)

    Shaaban, E. R.; Yahia, I. S.; Sharaf, E. R.

    2016-09-01

    The ZnSe thin films with different thicknesses have been deposited on polymer substrates for flexible optical devices applications. The XRD of different thicknesses for ZnSe films reveals the cubic structure of the films oriented along the (1 1 1) direction. The structural parameters such as particle size (40.41-105.24 nm) and lattice strain (6.5 × 10-3-14.7 × 10-3 lin-2m-4) were evaluated. Also AFM was used in order to obtain quantitative information on microstructure properties. The optical constants, the refractive index n and the absorption index k have been calculated from transmittance T and reflectance R through the spectral range of 400-2500 nm using Swanepoel's method. The optical constants (n, k) were calculated in medium and transparent regions. The energy gap of direct transition for polycrystalline ZnSe thin films was calculated in the strong absorption region and found to be increased from 2.55 eV to 2.70 eV with the increasing the film thickness. ZnSe/flexible substrates are good candidates for optoelectronic devices.

  17. Nano-structured CuO-Cu2O Complex Thin Film for Application in CH3NH3PbI3 Perovskite Solar Cells

    Science.gov (United States)

    Chen, Lung-Chieh; Chen, Cheng-Chiang; Liang, Kai-Chieh; Chang, Sheng Hsiung; Tseng, Zhong-Liang; Yeh, Shih-Chieh; Chen, Chin-Ti; Wu, Wen-Ti; Wu, Chun-Guey

    2016-09-01

    Nano-structured CuO-Cu2O complex thin film-based perovskite solar cells were fabricated on an indium tin oxide (ITO)-coated glass and studied. Copper (Cu) thin films with a purity of 99.995 % were deposited on an ITO-coated glass by magnetron reactive sputtering. To optimize the properties of the nano-structured CuO-Cu2O complex thin films, the deposited Cu thin films were thermally oxidized at various temperatures from 300 to 400 °C. A CH3NH3PbI3 perovskite absorber was fabricated on top of CuO-Cu2O complex thin film by a one-step spin-coating process with a toluene washing treatment. Following optimization, the maximum power conversion efficiency (PCE) exceeded 8.1 %. Therefore, the low-cost, solution-processed, stable nano-structured CuO-Cu2O complex thin film can be used as an alternative hole transport layer (HTL) in industrially produced perovskite solar cells.

  18. Toward High Performance Integrated Semiconductor Micro and Nano Lasers Enabled by Transparent Conducting Materials: from Thick Structure to Thin Film

    Science.gov (United States)

    Ou, Fang

    some novel laser design based on the TCO materials and the thin film structure. The InP based coplanar electrode FP laser using In2O3 as the n-type cladding electrode is demonstrated. The design of the electrically pumped photonic crystal laser is also discussed. Initial fabrication result is given, showing potential of realizing those nano-lasers.

  19. Studies of Nano-structured Se77Sb23- x Ge x Thin Films Prepared by Physical Vapor Condensation Technique

    Science.gov (United States)

    Alvi, M. A.

    2017-02-01

    Bulk Se77Sb23- x Ge x material with x = 4 and 12 was prepared by employing a melt quench technique. Its amorphous as well as glassy nature was confirmed by x-ray diffraction analysis and nonisothermal differential scanning calorimetry measurements. The physical vapor condensation technique was applied to prepare nanostructured thin films of Se77Sb23- x Ge x material. The surface morphology of the films was examined using field-emission scanning electron microscopy, revealing average particle size between 20 nm and 50 nm. Systematic investigation of optical absorption data indicated that the optical transition was indirect in nature. The dark conductivity (dc conductivity) of nano-structured Se77Sb23- x Ge x thin films was also investigated at temperatures from 313 K to 463 K, revealing that it tended to increase with increasing temperature. Analyses of our experimental data also indicate that the conduction is due to thermally supported tunneling of charge carriers in confined states close to the band edges. The calculated values of activation energy agree well with the optical bandgap.

  20. Structural and optical properties of nano-structured CdS thin films prepared by chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Rekha, E-mail: rekha.mittal07@gmail.com; Kumar, Dinesh; Chaudhary, Sujeet; Pandya, Dinesh K. [Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi-110016 (India)

    2016-05-06

    Cadmium sulfide (CdS) thin films have been deposited on conducting glass substrates by chemical bath deposition (CBD) technique. The effect of precursor concentration on the structural, morphological, compositional, and optical properties of the CdS films has been studied. Crystal structure of these CdS films is characterized by X-ray diffraction (XRD) and it reveals polycrystalline structure with mixture of cubic and wurtzite phases with grain size decreasing as precursor concentration is increased. Optical studies reveal that the CdS thin films have high transmittance in visible spectral region reaching 90% and the films possess direct optical band gap that decreases from 2.46 to 2.39 eV with decreasing bath concentration. Our study suggests that growth is nucleation controlled.

  1. Investigation of the Structural, Electrical, and Optical Properties of the Nano-Scale GZO Thin Films on Glass and Flexible Polyimide Substrates

    Directory of Open Access Journals (Sweden)

    Fang-Hsing Wang

    2016-05-01

    Full Text Available In this study, Ga2O3-doped ZnO (GZO thin films were deposited on glass and flexible polyimide (PI substrates at room temperature (300 K, 373 K, and 473 K by the radio frequency (RF magnetron sputtering method. After finding the deposition rate, all the GZO thin films with a nano-scale thickness of about 150 ± 10 nm were controlled by the deposition time. X-ray diffraction patterns indicated that the GZO thin films were not amorphous and all exhibited the (002 peak, and field emission scanning electron microscopy showed that only nano-scale particles were observed. The dependences of the structural, electrical, and optical properties of the GZO thin films on different deposition temperatures and substrates were investigated. X-ray photoemission spectroscopy (XPS was used to measure the elemental composition at the chemical and electronic states of the GZO thin films deposited on different substrates, which could be used to clarify the mechanism of difference in electrical properties of the GZO thin films. In this study, the XPS binding energy spectra of Ga2p3/2 and Ga2p1/2 peaks, Zn2p3/2 and Zn2p1/2 peaks, the Ga3d peak, and O1s peaks for GZO thin films on glass and PI substrates were well compared.

  2. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Prathap Pathi

    2017-01-01

    Full Text Available Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (<2 μm and 750 nm pitch arrays, scattering matrix simulations predict enhancements exceeding 90%. Absorption approaches the Lambertian limit at small thicknesses (<10 μm and is slightly lower (by ~5% at wafer-scale thicknesses. Parasitic losses are ~25% for ultra-thin (2 μm silicon and just 1%–2% for thicker (>100 μm cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.

  3. Identification and design of novel polymer-based mechanical transducers: A nano-structural model for thin film indentation

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, Joshua; Huang, Qian; Sirbuly, Donald J., E-mail: dsirbuly@ucsd.edu [Department of NanoEngineering, University of California San Diego, La Jolla, California 92093 (United States)

    2014-09-14

    Mechanical characterization is important for understanding small-scale systems and developing devices, particularly at the interface of biology, medicine, and nanotechnology. Yet, monitoring sub-surface forces is challenging with current technologies like atomic force microscopes (AFMs) or optical tweezers due to their probe sizes and sophisticated feedback mechanisms. An alternative transducer design relying on the indentation mechanics of a compressible thin polymer would be an ideal system for more compact and versatile probes, facilitating measurements in situ or in vivo. However, application-specific tuning of a polymer's mechanical properties can be burdensome via experimental optimization. Therefore, efficient transducer design requires a fundamental understanding of how synthetic parameters such as the molecular weight and grafting density influence the bulk material properties that determine the force response. In this work, we apply molecular-level polymer scaling laws to a first order elastic foundation model, relating the conformational state of individual polymer chains to the macroscopic compression of thin film systems. A parameter sweep analysis was conducted to observe predicted model trends under various system conditions and to understand how nano-structural elements influence the material stiffness. We validate the model by comparing predicted force profiles to experimental AFM curves for a real polymer system and show that it has reasonable predictive power for initial estimates of the force response, displaying excellent agreement with experimental force curves. We also present an analysis of the force sensitivity of an example transducer system to demonstrate identification of synthetic protocols based on desired mechanical properties. These results highlight the usefulness of this simple model as an aid for the design of a new class of compact and tunable nanomechanical force transducers.

  4. Surface Structure and Photocatalytic Activity of Nano-TiO2 Thin Film

    Science.gov (United States)

    Controlled titanium dioxide (TiO2) thin films were deposited on stainless steel surfaces using flame aerosol synthetic technique, which is a one-step coating process, that doesn’t require further calcination. Solid state characterization of the coatings was conducted by different...

  5. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells

    Science.gov (United States)

    Pathi, Prathap; Peer, Akshit; Biswas, Rana

    2017-01-01

    Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping. PMID:28336851

  6. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells.

    Science.gov (United States)

    Pathi, Prathap; Peer, Akshit; Biswas, Rana

    2017-01-13

    Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm² photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.

  7. Optimized absorption of solar radiations in nano-structured thin films of crystalline silicon via a genetic algorithm

    Science.gov (United States)

    Mayer, Alexandre; Muller, Jérôme; Herman, Aline; Deparis, Olivier

    2015-08-01

    We developed a genetic algorithm to achieve optimal absorption of solar radiation in nano-structured thin films of crystalline silicon (c-Si) for applications in photovoltaics. The device includes on the front side a periodic array of inverted pyramids, with conformal passivation layer (a-Si:H or AlOx) and anti-reflection coating (SiNx). The device also includes on the back side a passivation layer (a-Si:H) and a flat reflector (ITO and Ag). The geometrical parameters of the inverted pyramids as well as the thickness of the different layers must be adjusted in order to maximize the absorption of solar radiations in the c-Si. The genetic algorithm enables the determination of optimal solutions that lead to high performances by evaluating only a reduced number of parameter combinations. The results achieved by the genetic algorithm for a 40μm thick c-Si lead to short-circuit currents of 37 mA/cm2 when a-Si:H is used for the front-side passivation and 39.1 mA/cm2 when transparent AlOx is used instead.

  8. Scanning transmission X-ray microscopy of nano structured thin film catalysts for proton-exchange-membrane fuel cells

    Science.gov (United States)

    Lee, Vincent; Berejnov, Viatcheslav; West, Marcia; Kundu, Sumit; Susac, Darija; Stumper, Jürgen; Atanasoski, Radoslav T.; Debe, Mark; Hitchcock, Adam P.

    2014-10-01

    Scanning transmission X-ray microscopy (STXM) has been applied to characterize nano structured thin film (NSTF) catalysts implemented as electrode materials in proton-exchange-membrane (PEM) fuel cells. STXM is used to study all chemical constituents at various stages in the fabrication process, from the perylene red (PR149) starting material, through the formation of the uncoated perylene whiskers, their coated form with Pt-based catalyst, and toward the NSTF anode fully integrated into the catalyst coated membrane (CCM). CCM samples were examined prior to operational testing and after several different accelerated testing protocols: start-up/shut-down (SU/SD), and reversal tests. It was found that, while the perylene support material is present in the pre-test samples, it was completely absent in the post-test samples. We attribute this loss of perylene material to the presence of cracks in the catalyst combined with intensive hydrogenation processes happening at the anode during operation. Despite the loss of the perylene support, the platinum shells forming the NSTF anode catalyst layer performed well during the tests.

  9. Band gap and conductivity variations of ZnO nano structured thin films annealed under Vacuum

    Science.gov (United States)

    Vattappalam, Sunil C.; Thomas, Deepu; T, Raju Mathew; Augustine, Simon; Mathew, Sunny

    2015-02-01

    Zinc Oxide thin films were prepared by Successive Ionic layer adsorption and reaction technique(SILAR). The samples were annealed under vacuum and conductivity of the samples were taken at different temperatures. UV Spectrograph of the samples were taken and the band gap of each sample was found from the data. All the results were compared with that of the sample annealed under air. It was observed that the band gap decreases and concequently conductivity of the samples increases when the samples are annealed under vacuum.

  10. Structural and optical studied of nano structured lead sulfide thin films prepared by the chemical bath deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Al Din, Nasser Saad, E-mail: nsaadaldin@yahoo.com; Hussain, Nabiha, E-mail: nabihahssin@yahoo.com [Damascus University Faculty of Science, Department of physics, Homs (Syrian Arab Republic); Jandow, Nidhal, E-mail: nidhaljandow@yahoo.com [Al –Mustansiriyah University, College of Education, Department of physics, Baghdad (Iraq)

    2016-07-25

    Lead (II) Sulfide PbS thin films were deposited on glass substrates at 25°C by chemical bath deposition (CBD) method. The structural properties of the films were studied as a function of the concentration of Thiourea (CS (NH{sub 2}){sub 2}) as Source of Sulfide and deposition time. The surface morphology of the films was characterized by X-ray diffraction and SEM. The obtained results showed that the as-deposited films Polycrystalline had cubic crystalline phase that belong to S.G: Fm3m. We found that they have preferred orientation [200]. Also the thickness of thin films decrease with deposition time after certain value and, it observed free sulfide had orthorhombic phase. Optical properties showed that the thin films have high transmission at visible range and low transmission at UV, IR range. The films of PbS have direct band gap (I.68 - 2.32 ev) at 300 K the values of band energy decreases with increases thickness of the Lead (II) Sulfide films.

  11. Second harmonic generation in nano-structured thin-film lithium niobate waveguides

    CERN Document Server

    Wang, Cheng; Andrade, Nicolas; Venkataraman, Vivek; Ren, Xi-Feng; Guo, Guang-Can; Lončar, Marko

    2016-01-01

    Lithium niobate is the most well-known optical material with a second-order \\c{hi}(2) nonlinearity that is widely employed in modern optical technology. Integrated lithium niobate platform has recently emerged as a promising candidate for next-generation, high-efficiency wavelength conversion systems that allow dense packaging and mass-production. Here we demonstrate efficient, phase-matched second harmonic generation in lithographically-defined thin-film lithium niobate waveguides with sub-micron dimensions. Both natural phase matching in fixed-width waveguides and quasi-phase matching in periodically-grooved waveguides are theoretically proposed and experimentally demonstrated. Our low-loss (~2.52 dB/cm) nanowaveguides possess normalized conversion efficiencies as high as 41% W-1cm-2, promising for future on-chip quantum wavelength conversion.

  12. Formaldehyde gas sensor based on TiO2 thin membrane integrated with nano silicon structure

    Science.gov (United States)

    Zheng, Xuan; Ming, An-jie; Ye, Li; Chen, Feng-hua; Sun, Xi-long; Liu, Wei-bing; Li, Chao-bo; Ou, Wen; Wang, Wei-bing; Chen, Da-peng

    2016-07-01

    An innovative formaldehyde gas sensor based on thin membrane type metal oxide of TiO2 layer was designed and fabricated. This sensor under ultraviolet (UV) light emitting diode (LED) illumination exhibits a higher response to formaldehyde than that without UV illumination at low temperature. The sensitivities of the sensor under steady working condition were calculated for different gas concentrations. The sensitivity to formaldehyde of 7.14 mg/m3 is about 15.91 under UV illumination with response time of 580 s and recovery time of 500 s. The device was fabricated through micro-electro-mechanical system (MEMS) processing technology. First, plasma immersion ion implantation (PIII) was adopted to form black polysilicon, then a nanoscale TiO2 membrane with thickness of 53 nm was deposited by DC reactive magnetron sputtering to obtain the sensing layer. By such fabrication approaches, the nanoscale polysilicon presents continuous rough surface with thickness of 50 nm, which could improve the porosity of the sensing membrane. The fabrication process can be mass-produced for the MEMS process compatibility.

  13. Effects of dip-coating speed and annealing temperature on structural, morphological and optical properties of sol-gel nano-structured TiO2 thin films

    Science.gov (United States)

    Touam, Tahar; Atoui, Mohamed; Hadjoub, Ilhem; Chelouche, Azeddine; Boudine, Boubekeur; Fischer, Alexis; Boudrioua, Azzedine; Doghmane, Abdellaziz

    2014-09-01

    We reported material characterization of the nano-structured TiO2 thin films prepared by the sol-gel dip-coating process on glass substrates. The dependence of the structural, morphological and optical properties of the synthesized films on the fabrication parameters such as withdrawal velocity and annealing temperature were investigated by the techniques of X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-visible spectrophotometry. The results indicate that for the TiO2 films annealed at 500 °C there exhibits (1 0 1) XRD peak corresponding to the anatase phase of TiO2. The latter is consistent with the recorded Raman signal observed at 142 cm-1 (Eg mode) and 391 cm-1 (B1g mode), respectively. From the analyses made on the SEM micrographs and AFM images, it was revealed that the morphology and surface roughness of the thin films would depend on the withdrawal speed and the heat treatment temperature. The UV-visible spectroscopy analyses show that all the films were transparent in the visible region with an average transmittance of more than 70%. With an increase on the dip-coating speed from 1 cm/min to 3 cm/min, we observed a spectral red shift of the absorption edge from 3.76 eV to 3.71 eV, indicating a decrease in the bandgap energy (Eg) of the films.

  14. Magnetic Nano-structures

    Institute of Scientific and Technical Information of China (English)

    姚永德

    2004-01-01

    Fabrication of magnetic nano-structures with dots array and wires has been paid attention recently due to the application of high-density magnetic recording. In this study, we fabricated the magnetic dots array and wires through several ways that ensure the arrangement of magnetic dots and wires to be the structures we designed. Their magnetic properties are studied experimentally.

  15. Effects of stabilizer ratio on photoluminescence properties of sol-gel ZnO nano-structured thin films

    Energy Technology Data Exchange (ETDEWEB)

    Boudjouan, F. [Laboratoire de Génie de l' Environnement, Université de Bejaia, 06000 Bejaia (Algeria); Chelouche, A., E-mail: azeddinechelouche@gmail.com [Laboratoire de Génie de l' Environnement, Université de Bejaia, 06000 Bejaia (Algeria); Touam, T. [Laboratoire des Semi-conducteurs, Université Badji Mokhtar, BP 12, Annaba 23000 (Algeria); Djouadi, D. [Laboratoire de Génie de l' Environnement, Université de Bejaia, 06000 Bejaia (Algeria); Khodja, S. [Laboratoire des Semi-conducteurs, Université Badji Mokhtar, BP 12, Annaba 23000 (Algeria); Tazerout, M. [Laboratoire de Génie de l' Environnement, Université de Bejaia, 06000 Bejaia (Algeria); Ouerdane, Y. [Laboratoire Hubert Curien, Université Jean Monnet, 42 000 Saint-Etienne (France); Hadjoub, Z. [Laboratoire des Semi-conducteurs, Université Badji Mokhtar, BP 12, Annaba 23000 (Algeria)

    2015-02-15

    Nanostructured ZnO thin films with different molar ratios of MEA to zinc acetate (0.5, 1.0, 1.5 and 2.0) have been deposited on glass substrates by a sol–gel dip coating technique. X-ray diffraction, Scanning Electron Microscopy, UV–visible spectrophotometry and photoluminescence spectroscopy have been employed to investigate the effect of MEA stabilizer ratio on structural, morphological, absorbance and emission properties of the ZnO thin films. Diffraction patterns have shown that all the films are polycrystalline and exhibit a wurtzite hexagonal structure. The c axis orientation has been enhanced with increasing stabilizer ratio. SEM micrographs have revealed that the morphology of the ZnO films depend on stabilizer ratio. The UV–visible absorption spectra have demonstrated that the optical absorption is affected by stabilizer ratio. The photoluminescence spectra have indicated one ultraviolet and two visible emission bands (green and red), while band intensities are found to be dependent on stabilizer ratio. ZnO thin films deposited at MEA ratio of 1.0 show the highest UV emission while the minimum UV emission intensity is observed in thin films deposited at ratio of 0.5 and the maximum green has been recorded for films deposited at MEA ratio of 2.0. - Highlight: • c axis orientation increases with increasing MEA ratio. • The increase of MEA ration from 0.5 to 1.0 enhances greatly the UV emission. • The larger I{sub UV}/I{sub visible} is obtained for the MEA to Zn ratio of 1:1. • The MEA ratio of 0.5 favors the formation of large density of V{sub zn}. • The MEA ratio of 2.0 increases the V{sub o} density.

  16. Nano-enabled tribological thin film coatings: global patent scenario.

    Science.gov (United States)

    Sivudu, Kurva S; Mahajan, Yashwant R; Joshi, Shrikant V

    2014-01-01

    The aim of this paper is to present current status and future prospects of nano-enabled tribological thin film coatings based on worldwide patent landscape analysis. The study also presents an overview of technological trends by carrying out state-of-the-art literature analysis, including survey of corporate websites. Nanostructured tribological coatings encompass a wide spectrum of nanoscale microstructures, including nanocrystalline, nanolayered, nano-multilayered, nanocomposite, nanogradient structures or their unique combinations, which are composed of single or multi-component phases. The distinct microstructural features of the coatings impart outstanding tribological properties combined with multifunctional attributes to the coated components. Their unique combination of remarkable properties make them ideal candidates for a wide range of applications in diverse fields such as cutting and metalworking tools, biomedical devices, automotive engine components, wear parts, hard disc drives etc. The patent landscape analysis has revealed that nano-enabled tribological thin film coatings have significant potential for commercial applications in view of the lion's share of corporate industry in patenting activity. The largest patent portfolio is held by Japan followed by USA, Germany, Sweden and China. The prominent players involved in this field are Mitsubishi Materials Corp., Sandvik Aktiebolag, Hitachi Ltd., Sumitomo Electric Industries Ltd., OC Oerlikon Corp., and so on. The outstanding potential of nanostructured thin film tribological coatings is yet to be fully unravelled and, therefore, immense opportunities are available in future for microstructurally engineered novel coatings to enhance their performance and functionality by many folds.

  17. High-performance infrared light trapping in nano-needle structured p⁺ SnOx (x  ≤  1)/thin film n-Ge photodiodes on Si.

    Science.gov (United States)

    Wang, Xiaoxin; Wong, Andrew; Malek, Stephanie; Cai, Yan; Liu, Jifeng

    2015-06-01

    We report nano-needle structured conductive SnOx (x≤1) as a self-assembled electrode for high-efficiency light trapping in thin-film infrared (IR) photonic devices, benefiting from the high scattering efficiency, high density, and low IR loss of the nano-needles. We demonstrate a 2.2× responsivity enhancement for a 1.5-μm-thick Ge absorber in a nano-needled p(+) SnOx/n-Ge photodiode on Si at λ=1580  nm, in good agreement with theoretical calculation of 2.3× enhancement assuming no IR loss in the nano-needles. Such low-loss light trapping can potentially enable 15-30× absorption enhancement at λ=1600-1650  nm in the Ge layer when integrated with a perfect rear reflector.

  18. Effect of Sn Doping on the Properties of Nano-Structured ZnO Thin Films Deposited by Co-Sputtering Technique.

    Science.gov (United States)

    Islam, M A; Rahman, K S; Haque, F; Khan, N A; Akhtaruzzaman, M; Alam, M M; Ruslan, H; Sopian, K; Amin, N

    2015-11-01

    In this study, tin doped zinc oxide (ZnO:Sn) nano-structured thin films were successfully deposited by co-sputtering of ZnO and Sn on top of glass substrate. The effect of Sn doping on the microstructure, phase, morphology, optical and electrical properties of the films were extensively investigated by means of XRD, EDX, SEM, AFM, Hall Effect measurement, and UV-Vis spectrometry. The results showed that the undoped ZnO film exhibited preferred orientation along the c-axis of the hexagonal wurtzite structure. With increase of Sn doping, the peak position of the (002) plane was shifted to the higher 20 values, and ultimately changed to amorphous structure. The absorption edge was shifted to blue region which confirmed the excitonic quantum confinement effect in the films. Consequently, improved surface morphology with optical bandgap, reduced average particle size, reduced resistivity, enhanced Hall mobility and carrier concentration were observed in the doped films after vacuum annealing. Among all of the as-deposited and annealed ZnO:Sn films investigated in this study, annealed film doped with 8 at.% of Sn concentration exhibited the best properties with a bandgap of 3.84 eV, RMS roughness of 2.51 nm, resistivity of 2.36 ohm-cm, and Hall mobility of 83 cm2 V(-1) s(-1).

  19. Fabrication, ultra-structure characterization and in vitro studies of RF magnetron sputter deposited nano-hydroxyapatite thin films for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Surmeneva, Maria A. [Department of Theoretical and Experimental Physics, National Research Tomsk Polytechnic University, Tomsk 634050 (Russian Federation); Surmenev, Roman A., E-mail: rsurmenev@gmail.com [Department of Theoretical and Experimental Physics, National Research Tomsk Polytechnic University, Tomsk 634050 (Russian Federation); Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, 70569 Stuttgart (Germany); Nikonova, Yulia A.; Selezneva, Irina I. [Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino 142292 (Russian Federation); Ivanova, Anna A. [Department of Theoretical and Experimental Physics, National Research Tomsk Polytechnic University, Tomsk 634050 (Russian Federation); Putlyaev, Valery I. [Department of Chemistry, Moscow State University, Vorobievi Gory, 1, Moscow 119991 (Russian Federation); Prymak, Oleg; Epple, Matthias [Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, 45117 Essen (Germany)

    2014-10-30

    Highlights: • Growth of a columnar grain structure perpendicular to the substrate surface was observed. • Interplanar spacing distances measured using HRTEM were 0.82 and 0.28 nm, corresponding to the (0 0 1) and (2 1 1) lattice planes of hexagonal HA. • Grain size and crystallinity increased when increasing the deposition time. • Nanometer-thick low-crystallinity HA coatings with different thicknesses stimulated cells to attach, proliferate and form mineralized nodules. - Abstract: A series of nanostructured low-crystalline hydroxyapatite (HA) coatings averaging 170, 250, and 440 nm in thickness were deposited onto previously etched titanium substrates through radio-frequency (RF) magnetron sputtering. The HA coatings were analyzed using infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning and transmission electron microscopy (SEM and TEM). Cross sections of the thin specimens were prepared by FIB to study the microstructure of the coatings by TEM. The deposition process formed nano-scale grains, generating an amorphous layer at the substrate/coating interface and inducing the growth of a columnar grain structure perpendicular to the substrate surface. A microstructural analysis of the film confirmed that the grain size and crystallinity increased when increasing the deposition time. The nanostructured HA coatings were not cytotoxic, as proven by in vitro assays using primary dental pulp stem cells and mouse fibroblast NCTC clone L929 cells. Low-crystallinity HA coatings with different thicknesses stimulated cells to attach, proliferate and form mineralized nodules on the surface better than uncoated titanium substrates.

  20. Picosecond laser ablation of nano-sized WTi thin film

    Science.gov (United States)

    Petrović, S.; Gaković, B.; Peruško, D.; Desai, T.; Batani, D.; Čekada, M.; Radak, B.; Trtica, M.

    2009-08-01

    Interaction of an Nd:YAG laser, operating at 532 nm wavelength and pulse duration of 40 ps, with tungsten-titanium (WTi) thin film (thickness, 190 nm) deposited on single silicon (100) substrate was studied. Laser fluences of 10.5 and 13.4 J/cm2 were found to be sufficient for modification of the WTi/silicon target system. The energy absorbed from the Nd:YAG laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following WTi/silicon surface morphological changes were observed: (i) ablation of the thin film during the first laser pulse. The boundary of damage area was relatively sharp after action of one pulse whereas it was quite diffuse after irradiation with more than 10 pulses; (ii) appearance of some nano-structures (e.g., nano-ripples) in the irradiated region; (iii) appearance of the micro-cracking. The process of the laser interaction with WTi/silicon target was accompanied by formation of plasma.

  1. Heteroepitaxy of gallium-selenide on silicon(100) and (111): New silicon-compatible semiconductor thin films for nano structure formation

    Science.gov (United States)

    Ohta, Taisuke

    Silicon has been the backbone of modern electronics for decades; however, it is not readily compatible with some new types of electronics, such as optoelectronics or spintronics. We aim at overcoming this limitation by combining gallium-selenide (GaxSey) materials with silicon (Si) through heteroepitaxial growth. GaxSey materials are compatible with Si, and are optically and potentially magnetically active semiconductors. Their unusual crystal structures, layered GaSe and defected zinc-blende Ga2Se 3, may be exploited for unprecedented nanostructure formations. This dissertation demonstrates that GaxSey thin films can be grown epitaxially on Si(100) and (111) substrates into various nanostructure forms, namely 0-dimensional (0-D) "dots", 1-D "wires", 2-D "layers", and 3-D "bulk". We have found that hexagonal layered GaSe is formed on Si(111) with or without arsenic termination (Si(111):As), and defected zinc-blende Ga2Se3 is formed on arsenic terminated Si(100) (Si(100):As). The surfaces of GaSe/Si(111) and Ga 2Se3/Si(100):As are covered by triangle nanodots and oriented nanowire structures, respectively. We propose that different symmetry and bonding of the substrate surfaces induces different configurations of vacancies, resulting in the distinct surface nanostructures. We have achieved a thorough understanding for nanostructure formations of GaxSey by considering vacancies and surfaces as additional "elements" for stabilizing the structures. In contrast to layered GaSe/Si(111), we have found that Ga2Se3-GaAs alloy is formed in a zinc-blende phase at the interface of GaSe/Si(111):As. This signifies the bonding configuration of each element is responsible for determining the local composition; however, the atomic arrangement defined by the substrate symmetry plays a more decisive role in selecting GaxSey crystal structure for Ga xSey/Si heteroepitaxy. Through this study, we propose a generalized concept describing the stable structures of the selenide materials

  2. Effects of Topography in Nano-Structured Thin Films : A Lorentz Transmission Electron Microscopy and Electron Holography Study

    NARCIS (Netherlands)

    Hosson, Jeff Th.M. De; Raedt, Hans A. De

    2003-01-01

    This paper aims at applying advanced transmission electron microscopy (TEM) to functional materials, such as ultra-soft magnetic films for high-frequency inductors, to reveal the structure-property relationship. The ultimate goal is to delineate a more quantitative way to obtain information of the

  3. Room-temperature wide-range luminescence and structural, optical, and electrical properties of SILAR deposited Cu-Zn-S nano-structured thin films

    Science.gov (United States)

    Jose, Edwin; Kumar, M. C. Santhosh

    2016-09-01

    We report the deposition of nanostructured Cu-Zn-S composite thin films by Successive Ionic Layer Adsorption and Reaction (SILAR) method on glass substrates at room temperature. The structural, morphological, optical, photoluminescence and electrical properties of Cu-Zn-S thin films are investigated. The results of X-ray diffraction (XRD) and Raman spectroscopy studies indicate that the films exhibit a ternary Cu-Zn-S structure rather than the Cu xS and ZnS binary composite. Scanning electron microscope (SEM) studies show that the Cu-Zn-S films are covered well over glass substrates. The optical band gap energies of the Cu-Zn-S films are calculated using UV-visible absorption measurements, which are found in the range of 2.2 to 2.32 eV. The room temperature photoluminescence studies show a wide range of emissions from 410 nm to 565 nm. These emissions are mainly due to defects and vacancies in the composite system. The electrical studies using Hall effect measurements show that the Cu-Zn-S films are having p-type conductivity.

  4. Superhydrophobic Behavior on Nano-structured Surfaces

    Science.gov (United States)

    Schaeffer, Daniel

    2008-05-01

    Superhydrophobic behavior is observed in natural occurrences and has been thoroughly studied over the past few years. Water repellant properties on uniform arrays of vertically aligned nano-cones were investigated to determine the highest achievable contact angle (a measure of water drop repellency), which is measured from the reference plane on which the water drop sits to the tangent line of the point at which the drop makes contact with the reference plane. At low aspect ratios (height vs. width of the nano-cones), surface tension pulls the water into the nano-cone array, resulting in a wetted surface. Higher aspect ratios reverse the effect of the surface tension, resulting in a larger contact angle that causes water drops to roll off the surface. Fiber drawing, bundling, and redrawing are used to produce the structured array glass composite surface. Triple-drawn fibers are fused together, annealed, and sliced into thin wafers. The surface of the composite glass is etched to form nano-cones through a differential etching process and then coated with a fluorinated self-assembled monolayer (SAM). Cone aspect ratios can be varied through changes in the chemistry and concentration of the etching acid solution. Superhydrophobic behavior occurs at contact angles >150 and it is predicted and measured that optimal behavior is achieved when the aspect ratio is 4:1, which displays contact angles >=175 .

  5. Layered TiO2: PVK nano-composite thin films for photovoltaic applications. TiO2: PVK nano-composite thin films.

    Science.gov (United States)

    Kaune, G; Wang, W; Metwalli, E; Ruderer, M; Rossner, R; Roth, S V; Müller-Buschbaum, P

    2008-01-01

    The influence of the solvent used for spin-coating on the homogeneity of poly(N-vinylcarbazole) (PVK) films is investigated. Homogenous films are obtained only by the use of toluene, solution in tetrahydrofuran (THF) and chloroform results in radially oriented inhomogeneities and films prepared by use of N-methylpyrrolidone and dimethylacetamide show particle formation during spin-coating. Layered nano-composite thin films are prepared by spin-coating a PVK film on top of a nano-structured titanium dioxide ( TiO2) layer. The TiO2 thin films are prepared by a sol-gel process using an amphiphilic copolymer as structure-directing agent. Structural characterisation of the TiO2 :PVK nano-composite films is done by field emission scanning electron microscopy (FESEM) and grazing-incidence small-angle scattering (GISAXS). Bare TiO2 films are probed for comparison. Light is basically only absorbed in the ultraviolet regime and absorption slightly increases upon addition of PVK, which makes the layered TiO2 :PVK nano-composite thin films good candidates for UV photovoltaic devices. Furthermore, absorption remains stable over a period of several days.

  6. Enhanced superconductivity and superconductor to insulator transition in nano-crystalline molybdenum thin films

    Science.gov (United States)

    Sharma, Shilpam; Amaladass, E. P.; Sharma, Neha; Harimohan, V.; Amirthapandian, S.; Mani, Awadhesh

    2017-06-01

    Disorder driven superconductor to insulator transition via intermediate metallic regime is reported in nano-crystalline thin films of molybdenum. The nano-structured thin films have been deposited at room temperature using DC magnetron sputtering at different argon pressures. The grain size has been tuned using deposition pressure as the sole control parameter. A variation of particle sizes, room temperature resistivity and superconducting transition has been studied as a function of deposition pressure. The nano-crystalline molybdenum thin films are found to have large carrier concentration but very low mobility and electronic mean free path. Hall and conductivity measurements have been used to understand the effect of disorder on the carrier density and mobilities. Ioffe-Regel parameter is shown to correlate with the continuous metal-insulator transition in our samples.

  7. XPS study of palladium sensitized nano porous silicon thin film

    Indian Academy of Sciences (India)

    J Kanungo; L Selegård; C Vahlberg; K Uvdal; H Saha; S Basu

    2010-12-01

    Nano porous silicon (PS) was formed on -type monocrystalline silicon of 2–5 cm resistivity and (100) orientation by electrochemical anodization method using HF and ethanol as the electrolytes. High density of surface states, arising due to its nano structure, is responsible for the uncontrolled oxidation in air and for the deterioration of the PS surface with time. To stabilize the material PS surface was modified by a simple and low cost chemical method using PdCl2 solution at room temperature. X-ray photoelectron spectroscopy (XPS) was performed to reveal the chemical composition and the relative concentration of palladium on the nanoporous silicon thin films. An increase of SiO2 formation was observed after PdCl2 treatment and presence of palladium was also detected on the modified surface. – characteristics of Al/PS junction were studied using two lateral Al contacts and a linear relationship was obtained for Pd modified PS surface. Stability of the contact was studied for a time period of around 30 days and no significant ageing effect could be observed.

  8. Preparation of Nano-crystalline Tungsten Carbide Thin Film by Magnetron Sputtering and Their Electrocatalytic Property for PNP Reduction

    Institute of Scientific and Technical Information of China (English)

    Hua Jun ZHENG; Jian Guo HUANG; Chun An MA

    2005-01-01

    Nano-crystalline tungsten carbide thin films were deposited on Ni substrates by magnetron sputtering using WC as target material. The crystal structure and morphology of the thin films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Electrochemical investigations showed that the electrode of the thin film exhibited higher electrocatalytic activity in the reaction of p-nitrophenol (PNP) reduction. FT-IR analysis indicated that p-aminophenol (PAP) was synthesized after two step reduction of PNP on nano-crystalline tungsten carbide thin film electrode.

  9. Nano-oxide thin films deposited via atomic layer deposition on microchannel plates.

    Science.gov (United States)

    Yan, Baojun; Liu, Shulin; Heng, Yuekun

    2015-01-01

    Microchannel plate (MCP) as a key part is a kind of electron multiplied device applied in many scientific fields. Oxide thin films such as zinc oxide doped with aluminum oxide (ZnO:Al2O3) as conductive layer and pure aluminum oxide (Al2O3) as secondary electron emission (SEE) layer were prepared in the pores of MCP via atomic layer deposition (ALD) which is a method that can precisely control thin film thickness on a substrate with a high aspect ratio structure. In this paper, nano-oxide thin films ZnO:Al2O3 and Al2O3 were prepared onto varied kinds of substrates by ALD technique, and the morphology, element distribution, structure, and surface chemical states of samples were systematically investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoemission spectroscopy (XPS), respectively. Finally, electrical properties of an MCP device as a function of nano-oxide thin film thickness were firstly studied, and the electrical measurement results showed that the average gain of MCP was greater than 2,000 at DC 800 V with nano-oxide thin film thickness approximately 122 nm. During electrical measurement, current jitter was observed, and possible reasons were preliminarily proposed to explain the observed experimental phenomenon.

  10. Magnetic Micro/Nano Structures for Biological Manipulation

    Science.gov (United States)

    Huang, Chen-Yu; Hsieh, Teng-Fu; Chang, Wei-Chieh; Yeh, Kun-Chieh; Hsu, Ming-Shinn; Chang, Ching-Ray; Chen, Jiann-Yeu; Wei, Zung-Hang

    2016-05-01

    Biomanipulation based on micro/nano structures is an attractive approach for biotechnology. To manipulate biological systems by magnetic forces, the magnetic labeling technology utilized magnetic nanoparticles (MNPs) as a common rule. Ferrofluid, well-dispersed MNPs, can be used for magnetic modification of the surface or as molds to form organized microstructures. For magnetic-based micro/nano structures, different methods to modulate magnetic field at the microscale have been developed. Specifically, this review focused on a new strategy which uses the concept of micromagnetism of patterned magnetic thin film with specific domain walls configurations to generate stable magnetic poles for cell patterning.

  11. Aspects of Characterisation of Thin Coating Adhesion at the Nano-Scale

    Institute of Scientific and Technical Information of China (English)

    Jisheng E; Aiyang Zhang; Ben D. Beake

    2002-01-01

    In response to current development of materials in nano-science,characterisation of thin coating adhesion on a nano-scale becomes one of the most important research areas,as new coatings get ever thinner and more technologically advanced. With a review of technology and mechanisms of evaluating the adhesion failure of coatings,three techniques,nano impact ,nano-scratch and nano-indentation techniques ,for charactering the adhesion of thin coatings on a nano scale are described.Results of charactering the adhesion faliure of thin coatings using three different techniques indicate that the nano-scratch and nano-indentation techniques are very useful tools ,particularly in charactering the performance of thin coatings under nano-abra sive wear conditions. However,results from these types of tests cannot be easily applied to predict the performance of coatings whose are subject to nano-erosive wear,cyclic nano-fatigue or multiple nano-impacts during service. Instead,results of the new dynamic testing technique ,impact technique ,are found to correlate well with the coating performance under fatigue conditions,precisely because the impact test more closely simulates the actual contact (adhesion failure and wear)conditions of thin coatings occurring in nano-erosive/nano-fatigue/nano-impact wear.

  12. Microstructural properties of multi-nano-layered YSZ thin films

    Energy Technology Data Exchange (ETDEWEB)

    Amezaga-Madrid, P.; Antunez-Flores, W.; Gonzalez-Hernandez, J.; Saenz-Hernandez, J.; Campos-Venegas, K.; Solis-Canto, O.; Ornelas-Gutierrez, C.; Vega-Becerra, O.; Martinez-Sanchez, R. [Centro de Investigacion en Materiales Avanzados S.C., Miguel de Cervantes 120, Chihuahua, Chih, CP. 31109 (Mexico); Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.m [Centro de Investigacion en Materiales Avanzados S.C., Miguel de Cervantes 120, Chihuahua, Chih, CP. 31109 (Mexico)

    2010-04-16

    We report the fabrication of submicron, multi-nano-layered, yttria-stabilized zirconia (YSZ) thin films by aerosol assisted CVD. The film consisted of a periodic stack of several layers, a few nanometers thick, of the same composition but different density; formation of voids during synthesis originate the low-density layer. Grazing incidence X-ray diffraction (GIXRD), X-ray reflectometry, high-resolution transmission electron microscopy (HRTEM) and high angle annular dark field (HAADF) images were employed to analyze the microstructure of the films. GIXRD pattern showed characteristic peaks of cubic zirconia. Peak broadening in the pattern comes from a microstructure composed of nanocrystals, but principally due to the multilayered structure, that cause satellite peaks around the Bragg reflections. Lattice fringes measurement in HRTEM and HAADF images was consistent with the interplanar distance of the YSZ cubic phase. Additionally, lattice parameter obtained from selected area electron diffraction and GIXRD patterns was around 0.513 nm, in agreement to values reported in the literature for YSZ.

  13. An Investigation of Structural and Electrical Properties of Nano Crystalline SnO2:Cu Thin Films Deposited by Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    J. Podder

    2011-11-01

    Full Text Available Pure tin oxide (SnO2 and Cu doped SnO2 thin films have been deposited onto glass substrates by a simple spray pyrolysis technique under atmospheric pressure at temperature 350 °C. The doping concentration of Cu was varied from 1 to 8 wt. % while all other deposition parameters such as spray rate, carrier air gas pressure, deposition time, and distance between spray nozzle to substrate were kept constant. Surface morphology of the as-deposited thin films has been studied by Scanning Electron Microscopy (SEM. The SEM micrograph of the films shows uniform deposition. The structural properties of the as-deposited and annealed thin films have been studied by XRD and the electrical characterization was performed by Van-der Pauw method. The as-deposited films are found polycrystalline in nature with tetragonal crystal structure. Average grain sizes of pure and Cu doped SnO2 thin film have been obtained in the range of 7.2445 Å to 6.0699 Å, which indicates the nanometric size of SnO2 grains developed in the film. The resistivity of SnO2 films was found to decrease initially from 4.5095×10−4 Ωm to 1.1395× 10−4 Ωm for concentration of Cu up to 4 % but it was increased further with increasing of Cu concentrations. The experimental results depict the suitability of this material for using as transparent and conducting window materials in solar cells and gas sensors.

  14. Nano-crystalline thin and nano-particulate thick TiO{sub 2} layer: Cost effective sequential deposition and study on dye sensitized solar cell characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Das, P.; Sengupta, D. [Centre for Advanced Materials Processing, CSIR-Central Mechanical Engineering Research Institute, Durgapur, 713209 West Bengal (India); CSIR-Central Mechanical Engineering Research Institute, Academy of Scientific and Innovative Research (AcSIR), Durgapur, 713209 West Bengal (India); Kasinadhuni, U. [Department of Engineering Physics, Bengal College of Engineering and Technology, Durgapur, West Bengal (India); Mondal, B. [Centre for Advanced Materials Processing, CSIR-Central Mechanical Engineering Research Institute, Durgapur, 713209 West Bengal (India); Mukherjee, K., E-mail: kalisadhanm@yahoo.com [Centre for Advanced Materials Processing, CSIR-Central Mechanical Engineering Research Institute, Durgapur, 713209 West Bengal (India)

    2015-06-15

    Highlights: • Thin TiO{sub 2} layer is deposited on conducting substrate using sol–gel based dip coating. • TiO{sub 2} nano-particles are synthesized using hydrothermal route. • Thick TiO{sub 2} particulate layer is deposited on prepared thin layer. • Dye sensitized solar cells are made using thin and thick layer based photo-anode. • Introduction of thin layer in particulate photo-anode improves the cell efficiency. - Abstract: A compact thin TiO{sub 2} passivation layer is introduced between the mesoporous TiO{sub 2} nano-particulate layer and the conducting glass substrate to prepare photo-anode for dye-sensitized solar cell (DSSC). In order to understand the effect of passivation layer, other two DSSCs are also developed separately using TiO{sub 2} nano-particulate and compact thin film based photo-anodes. Nano-particles are prepared using hydrothermal synthesis route and the compact passivation layer is prepared by simply dip coating the precursor sol prepared through wet chemical route. The TiO{sub 2} compact layer and the nano-particles are characterised in terms of their micro-structural features and phase formation behavior. It is found that introduction of a compact TiO{sub 2} layer in between the mesoporous TiO{sub 2} nano-particulate layer and the conducting substrate improves the solar to electric conversion efficiency of the fabricated cell. The dense thin passivation layer is supposed to enhance the photo-excited electron transfer and prevent the recombination of photo-excited electrons.

  15. Preparation of nano-polycrystalline WO3 thin films and their solid-state electrochromic display devices.

    Science.gov (United States)

    Luo, Jianyi; Zeng, Qingguang; Long, Yongbing; Wang, Yi

    2013-02-01

    In this paper, nano-polycrystalline WO3 thin films with the thickness in the range of 100-200 nm have been uniformly prepared on the designed regions of ITO (indium tin oxide) glass substrates by thermal evaporation deposition. Their crystal structures, surface morphologies and uniformities are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM), respectively. The solid-state electrochromic display (ECD) devices based on these nano-polycrystalline WO3 thin films have been also fabricated and have demonstrated to have better performance than normal thin films, including shorter response time, higher contrast, and furthermore, higher stability to keep the colored state without power consumption. These results demonstrate nano-polycrystalline WO3 thin films can be applied to improve the performance of ECD devices, especially suitable to static display.

  16. 3D nano-structures for laser nano-manipulation

    Directory of Open Access Journals (Sweden)

    Gediminas Seniutinas

    2013-09-01

    Full Text Available The resputtering of gold films from nano-holes defined in a sacrificial PMMA mask, which was made by electron beam lithography, was carried out with a dry plasma etching tool in order to form well-like structures with a high aspect ratio (height/width ≈ 3–4 at the rims of the nano-holes. The extraordinary transmission through the patterns of such nano-wells was investigated experimentally and numerically. By doing numerical simulations of 50-nm and 100-nm diameter polystyrene beads in water and air, we show the potential of such patterns for self-induced back-action (SIBA trapping. The best trapping conditions were found to be a trapping force of 2 pN/W/μm2 (numerical result exerted on a 50-nm diameter bead in water. The simulations were based on the analytical Lorentz force model.

  17. Anatase TiO{sub 2} hierarchical structures composed of ultra-thin nano-sheets exposing high percentage {0 0 1} facets and their application in quantum-dot sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Dapeng, E-mail: dpengwu@126.com [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Collaborative Innovation Center of Henan Province for Green Motive Power and Key Materials, Henan Key Laboratory of Photovoltaic Materials, Henan Normal University, Xinxiang, Henan 453007 (China); Zhang, Shuo; Jiang, Shiwei; He, Jinjin [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Jiang, Kai [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Collaborative Innovation Center of Henan Province for Green Motive Power and Key Materials, Henan Key Laboratory of Photovoltaic Materials, Henan Normal University, Xinxiang, Henan 453007 (China)

    2015-03-05

    Graphical abstract: TiO{sub 2} hierarchical structures assembled from ultra-thin nanosheets exposing ∼90% {0 0 1} facets were employed as photoanode materials to improve the performance of CdS/CdSe co-sensitized solar cells. - Highlights: • THSs composited of nanosheets exposing high percent {0 0 1} facets were prepared. • THSs improve the QDs loading amount and light scattering of the photoanode. • THSs suppress the carrier recombination and finally lead to ∼25% PCE improvement. - Abstract: TiO{sub 2} hierarchical structures (THSs) composed of ultra-thin nano-sheets exposing ∼90% {0 0 1} facets were prepared via a hydrothermal method. Time dependent trails revealed the formation of THSs experienced a self-assemble process. The as-prepared product were used as the photoanode materials for CdS/CdSe co-sensitized solar cells, and the THSs/nanoparticle hybrid photoanode demonstrated a power conversion efficiency of 3.47%, indicating ∼25% improvement compared with the nanoparticle cell.

  18. Enhanced superconductivity and superconductor to insulator transition in nano-crystalline molybdenum thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Shilpam; Amaladass, E.P. [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Sharma, Neha [Surface & Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Harimohan, V. [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Amirthapandian, S. [Materials Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Mani, Awadhesh, E-mail: mani@igcar.gov.in [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2017-06-01

    Disorder driven superconductor to insulator transition via intermediate metallic regime is reported in nano-crystalline thin films of molybdenum. The nano-structured thin films have been deposited at room temperature using DC magnetron sputtering at different argon pressures. The grain size has been tuned using deposition pressure as the sole control parameter. A variation of particle sizes, room temperature resistivity and superconducting transition has been studied as a function of deposition pressure. The nano-crystalline molybdenum thin films are found to have large carrier concentration but very low mobility and electronic mean free path. Hall and conductivity measurements have been used to understand the effect of disorder on the carrier density and mobilities. Ioffe-Regel parameter is shown to correlate with the continuous metal-insulator transition in our samples. - Highlights: • Thin films of molybdenum using DC sputtering have been deposited on glass. • Argon background pressure during sputtering was used to tune the crystallite sizes of films. • Correlation in deposition pressure, disorder and particle sizes has been observed. • Disorder tuned superconductor to insulator transition along with an intermediate metallic phase has been observed. • Enhancement of superconducting transition temperature and a dome shaped T{sub C} vs. deposition pressure phase diagram has been observed.

  19. Spin Coated Nano Scale PMMA Films for Organic Thin Film Transistors

    Science.gov (United States)

    Shekar, B. Chandar; Sathish, S.; Sengoden, R.

    Nano scale poly methyl methacrylate (PMMA) films are prepared by spin coating the solution of PMMA on to p-Si substrate. The thickness of the films coated is measured by Ellipsometry. The SA-XRD spectrum of the as grown and annealed films indicated the amorphous nature. The SEM analysis revealed no pinholes, pits and dendritic features on the surface. Both as grown and annealed films indicated smooth surface and amorphous structure. The capacitance-voltage (C-V) behaviour of the metal-insulator-semiconductor (MIS) structure with Al/PMMA/p-Si has been studied. The C-V behaviour carried out for various frequencies (f) ranging from 20 kHz to 1 MHz and for a bias voltage range of -20 V to +20 V. Both as grown and annealed films showed a small flat band voltage (VFB) shift towards the negative voltage. The small shift in the VFB observed may be due to charge traps and de-traps. The obtained C-V behaviour for as grown and annealed films indicated that as grown PMMA nano scale thin films do not have many defects such as voids and inhomogeneity etc. The observed C-V behavior, a very low shift in the flat band voltage (VFB 0); reasonably higher dielectric constant values; thermal stability up to 2800C; amorphous and smooth surface implies that nano scale thin PMMA film coated by spin coating could be used as an efficient dielectric layer in field effect organic thin film transistors (OTFTs).

  20. Effect of complexing agent TEA: The structural, morphological, topographical and optical properties of Fe{sub x}S{sub x} nano thin films deposited by SILAR technique

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, K., E-mail: 1984manikandan@gmail.com [Department of Physics, Anna University BIT Campus, Tiruchirappalli 620 024, Tamilnadu (India); Mani, P. [Department of Physics, Anna University BIT Campus, Tiruchirappalli 620 024, Tamilnadu (India); Surendra Dilip, C. [Department of Chemistry, Anna University BIT Campus, Tiruchirappalli 620 024, Tamilnadu (India); Valli, S. [Department of Physics, M.I.E.T. Arts and Science College, Tiruchirappalli 620 007, Tamilnadu (India); Fermi Hilbert Inbaraj, P.; Joseph Prince, J. [Department of Physics, Anna University BIT Campus, Tiruchirappalli 620 024, Tamilnadu (India)

    2014-01-01

    Iron sulfide thin films (Fe{sub x}S{sub x}) (x = 0.05 M, 0.10 M, 0.15 M, 0.20 M and 0.25 M) were deposited by SILAR method from equimolar and equivolume aqueous solutions of ferrous nitrate and sodium sulfide with the addition of complexing agent TEA. The structural, morphological and optical characteristics of the films were derived from X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV–vis spectral techniques. The mixed characteristics (crystalline and amorphous) of the deposited films and the increasing crystalline qualities with the concentrations were understood from the XRD analysis. The grain sizes and roughness of the films were decreases with the increasing concentration and also at the higher concentration films are shown by the same images presence of hexagonal like crystallite structure. The influence of complexing agent TEA on the surface roughness and morphological properties are confirmed by the atomic force microscope (AFM) results. The effect of increasing substrate concentration on the absorption and transmission measurements and its impact on the optical band-gap energy were enumerated from the UV–vis analysis.

  1. Effect of complexing agent TEA: The structural, morphological, topographical and optical properties of FexSx nano thin films deposited by SILAR technique

    Science.gov (United States)

    Manikandan, K.; Mani, P.; Surendra Dilip, C.; Valli, S.; Fermi Hilbert Inbaraj, P.; Joseph Prince, J.

    2014-01-01

    Iron sulfide thin films (FexSx) (x = 0.05 M, 0.10 M, 0.15 M, 0.20 M and 0.25 M) were deposited by SILAR method from equimolar and equivolume aqueous solutions of ferrous nitrate and sodium sulfide with the addition of complexing agent TEA. The structural, morphological and optical characteristics of the films were derived from X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-vis spectral techniques. The mixed characteristics (crystalline and amorphous) of the deposited films and the increasing crystalline qualities with the concentrations were understood from the XRD analysis. The grain sizes and roughness of the films were decreases with the increasing concentration and also at the higher concentration films are shown by the same images presence of hexagonal like crystallite structure. The influence of complexing agent TEA on the surface roughness and morphological properties are confirmed by the atomic force microscope (AFM) results. The effect of increasing substrate concentration on the absorption and transmission measurements and its impact on the optical band-gap energy were enumerated from the UV-vis analysis.

  2. Non-linear optics of nano-scale pentacene thin film

    Science.gov (United States)

    Yahia, I. S.; Alfaify, S.; Jilani, Asim; Abdel-wahab, M. Sh.; Al-Ghamdi, Attieh A.; Abutalib, M. M.; Al-Bassam, A.; El-Naggar, A. M.

    2016-07-01

    We have found the new ways to investigate the linear/non-linear optical properties of nanostructure pentacene thin film deposited by thermal evaporation technique. Pentacene is the key material in organic semiconductor technology. The existence of nano-structured thin film was confirmed by atomic force microscopy and X-ray diffraction. The wavelength-dependent transmittance and reflectance were calculated to observe the optical behavior of the pentacene thin film. It has been observed the anomalous dispersion at wavelength λ 800. The non-linear refractive index of the deposited films was investigated. The linear optical susceptibility of pentacene thin film was calculated, and we observed the non-linear optical susceptibility of pentacene thin film at about 6 × 10-13 esu. The advantage of this work is to use of spectroscopic method to calculate the liner and non-liner optical response of pentacene thin films rather than expensive Z-scan. The calculated optical behavior of the pentacene thin films could be used in the organic thin films base advanced optoelectronic devices such as telecommunications devices.

  3. Microwave Plasma Chemical Vapor Deposition of Nano-Structured Sn/C Composite Thin-Film Anodes for Li-ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, Cynthia; Marcinek, M.; Hardwick, L.J.; Richardson, T.J.; Song, X.; Kostecki, R.

    2008-02-01

    In this paper we report results of a novel synthesis method of thin-film composite Sn/C anodes for lithium batteries. Thin layers of graphitic carbon decorated with uniformly distributed Sn nanoparticles were synthesized from a solid organic precursor Sn(IV) tert-butoxide by a one step microwave plasma chemical vapor deposition (MPCVD). The thin-film Sn/C electrodes were electrochemically tested in lithium half cells and produced a reversible capacity of 440 and 297 mAhg{sup -1} at C/25 and 5C discharge rates, respectively. A long term cycling of the Sn/C nanocomposite anodes showed 40% capacity loss after 500 cycles at 1C rate.

  4. Structural properties of produced CuO/NiO/glass thin layers Produced by chemical method

    Directory of Open Access Journals (Sweden)

    A. Ramezani

    2016-12-01

    Full Text Available Nickel Oxide and Copper oxide on Nickel Oxide thin layers were produced by chemical bath deposition method. There nano structures were investigated by SEM and EDAX analysis. By producing CuO/NiO/glass sandwich layers nano structure of NiO/glass layer changed and fraction of voids decreases. In sandwich layer physical property of outer layer was dominant

  5. Dielectric breakdown in nano-porous thin films

    Science.gov (United States)

    Borja, Juan Pablo

    Unknown to most computer users and mobile device enthusiasts, we have finally entered into a critical age of chip manufacturing. January of 2014 marks the official start of the quest by the semiconductor industry to successfully integrate sub 14nm process technology nodes in accordance to the International Technology Roadmap for Semiconductors (ITRS). The manufacturing of nano-scale features represents a major bottleneck of its own. However, a bigger challenge lies in reliably isolating the massive chip interconnect network. The present work is aimed at generating a theoretical and experimental framework to predict dielectric breakdown for thin films used in computer chip components. Here, a set of experimental techniques are presented to assess and study dielectric failure in novel thin films. A theory of dielectric breakdown in thin nano-porous films is proposed to describe combined intrinsic and metal ion catalyzed failure. This theory draws on experimental evidence as well as fundamental concepts from mass and electronic charge transport. The drift of metal species was found to accelerate intrinsic dielectric failure. The solubility of metals species such as Cu was found to range from 7.0x1025 ions/m3 to 1.86x1026 ions/m3 in 7% porous SiCOH films. The diffusion coefficient for Cu species was found to span from 4.2x10-19 m2/s to 1.86x10-21 m2/s. Ramped voltage stress experiments were used to identify intrinsic failure from metal catalyzed failure. Intrinsic breakdown is defined when time to failure against applied field ramp rate results in ∂(ln(TTF))/∂(ln(R)) ≈ -1. Intrinsic failure was studied using Au. Here, ∂(ln(TTF))/∂(ln(R)) ≈ -0.95, which is an experimental best case scenario for intrinsic failure. Au is commonly reluctant to ionize which means that failure occurs in the absence of ionic species. Metal catalyzed failure was investigated using reactive electrodes such as Cu, and Ag. Here, trends for ∂(ln(TTF))/∂(ln(R)) significantly

  6. Superior light trapping in thin film silicon solar cells through nano imprint lithography

    Energy Technology Data Exchange (ETDEWEB)

    Soppe, W.J.; Dorenkamper, M.S.; Schropp, R.E.I.; Pex, P.P.A.C.

    2013-10-15

    ECN and partners have developed a fabrication process based on nanoimprint lithography (NIL) of textures for light trapping in thin film solar cells such as thin-film silicon, OPV, CIGS and CdTe. The process can be applied in roll-to-roll mode when using a foil substrate or in roll-to-plate mode when using a glass substrate. The lacquer also serves as an electrically insulating layer for cells if steel foil is used as substrate, to enable monolithic series interconnection. In this paper we will show the superior light trapping in thin film silicon solar cells made on steel foil with nanotextured back contacts. We have made single junction a-Si and {mu}c-Si and a-Si/{mu}c-Si tandem cells, where we applied several types of nano-imprints with random and periodic structures. We will show that the nano-imprinted back contact enables more than 30% increase of current in comparison with non-textured back contacts and that optimized periodic textures outperform state-of-the-art random textures. For a-Si cells we obtained Jsc of 18 mA/cm{sup 2} and for {mu}c-Si cells more than 24 mA/cm{sup 2}. Tandem cells with a total Si absorber layer thickness of only 1350 nm have an initial efficiency of 11%.

  7. Polarization conversion based on plasmonic phase control by an ultra-thin metallic nano-strips

    Science.gov (United States)

    Wei, Helei; Hu, Dejiao; Deng, Yunsheng; Wu, Xuannan; Xiao, Xiao; Hou, Yidong; Wang, Yunjiao; Shi, Ruiying; Wang, Deqiang; Du, Jinglei

    2016-12-01

    Ultra-thin metallic nano-strips (thinner than skin depth) can lead to anomalous reflection for a transverse magnetic (TM) incidence of some wave-lengths, due to the phase modulation of localized surface plasmon resonance. Based on the principle above, we proposed a method of polarization modulation using ultra-thin metallic nano-strips. When irradiating nano-strips vertically by light with a given polarized angle, we can utilize the phase difference of the TM transmission and transverse electric (TE) transmission near anomalous reflection region to modulate transmission polarization. We have designed and fabricated the ultra-thin metallic nano-strips with the function of quarter-wave plate, the attained transmission Stokes parameter S3 is 0.95. The nano-strips is easy to design and fabricate, also compatible with other optics devices, hence has the potential applications in integrated optics field.

  8. Synthesis of structurally controlled nano carbons - in particular the nano barrel carbon

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, M. [FOI, Swedish Defence Research Agency, Dept. of Protection and Materials, Tumba (Sweden); Palmqvist, U. [IM, Swedish Institute for Metals Research, Drottning Kristinas vag 48, Stockholm (Sweden); Alberius, P.C.A. [YKI, Institute for Surface Chemistry, Stockholm (Sweden); Ekstrom, T. [Materials Science, Royal Institute of Technology, Stockholm (Sweden); Nygren, M.; Lidin, S. [Stockholm University, Inorganic Chemistry, Stockholm (Sweden)

    2003-01-01

    Nano-porous carbons have been prepared through a selective etching reaction, performed by halogenation of aluminum carbide. The structures obtained can be controlled by varying the chlorination temperature. The unique set of nano-carbons obtained include nano-porous amorphous structures, the nano-barrel structure and a nano-graphitic structure as chlorination temperatures were increased from 400 deg. C to 1000 deg. C. The synthesis process gives a pure product with high yield, and may be scaled up to produce bulk amounts. (authors)

  9. Deposition and thermal characterization of nano-structured aluminum nitride thin film on Cu-W substrate for high power light emitting diode package.

    Science.gov (United States)

    Cho, Hyun Min; Kim, Min-Sun

    2014-08-01

    In this study, we developed AlN thick film on metal substrate for hybrid type LED package such as chip on board (COB) using metal printed circuit board (PCB). Conventional metal PCB uses ceramic-polymer composite as electrical insulating layer. Thermal conductivities of such type dielectric film are typically in the range of 1~4 W/m · K depending on the ceramic filler. Also, Al or Cu alloy are mainly used for metal base for high thermal conduction to dissipate heat from thermal source mounted on metal PCB. Here we used Cu-W alloy with low thermal expansion coefficient as metal substrate to reduce thermal stress between insulating layer and base metal. AlN with polyimide (PI) powder were used as starting materials for deposition. We could obtain very high thermal conductivity of 28.3 W/m · K from deposited AlN-PI thin film by AlN-3 wt% PI powder. We made hybrid type high power LED package using AlN-PI thin film. We tested thermal performance of this film by thermal transient measurement and compared with conventional metal PCB substrate.

  10. The study of structural properties of carbon nanotubes decorated with NiFe{sub 2}O{sub 4} nanoparticles and application of nano-composite thin film as H{sub 2}S gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Hajihashemi, R., E-mail: Rezvan.hajihashemi@yahoo.com [Department of Physics, Payame Noor University, Mashhad (Iran, Islamic Republic of); Rashidi, Ali M.; Alaie, M. [Nanotechnology Research Center, Research Institute of Petroleum Industry, P.O., Tehran (Iran, Islamic Republic of); Mohammadzadeh, R. [Department of Physics, Shahreza Branch, Islamic Azad University, Shahreza (Iran, Islamic Republic of); Izadi, N. [Nanotechnology Research Center, Research Institute of Petroleum Industry, P.O., Tehran (Iran, Islamic Republic of)

    2014-11-01

    Nano-composite of multiwall carbon nanotube, decorated with NiFe{sub 2}O{sub 4} nanoparticles (NiFe{sub 2}O{sub 4}–MWCNT), was synthesized using the sol–gel method. NiFe{sub 2}O{sub 4}–MWCNTs were characterized using different methods such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM). The average size of the crystallites is 23.93 nm. The values of the saturation magnetization (M{sub S}), coercivity (H{sub C}) and retentivity (M{sub R}) of NiFe{sub 2}O{sub 4}–MWCNTs are obtained as 15 emu g{sup −1}, 21 Oe and 5 emu g{sup −1}, respectively. In this research, NiFe{sub 2}O{sub 4}–MWCNT thin films were prepared with the spin-coating method. These thin films were used as the H{sub 2}S gas sensor. The results suggest the possibility of the utilization of NiFe{sub 2}O{sub 4}–MWCNT nano-composite, as the H{sub 2}S detector. The sensor shows appropriate response towards 100 ppm of H{sub 2}S at 300 °C. - Highlights: • Nano-composite the average size of the crystallites is 23.93 nm. • NiFe{sub 2}O{sub 4} thin films were prepared with spin-coating method. • These thin films were used as the H{sub 2}s gas sensor. • The sensor shows appropriate response towards 100 ppm of H{sub 2}S at 300 °C.

  11. Tailored Optical Polarization in Nano-Structured Metamaterials

    CERN Document Server

    Mendoza, Bernardo S

    2016-01-01

    A very efficient method for the calculation of the effective optical response of nano-structured composite systems allows the design of metamaterials tailored for specific optical polarization properties. We use our method to design 2D periodic arrays of sub-wavelength dielectric inclusions within nanometric supported metallic thin films which behave as either an almost perfect linearly dichroic system, as a controllable source of circular polarized light, as a system with a large circular dichroism, or as a circular polarizer. All of these systems may be tuned over a wide energy range.

  12. Recent development of antifouling polymers: structure, evaluation, and biomedical applications in nano/micro-structures.

    Science.gov (United States)

    Liu, Lingyun; Li, Wenchen; Liu, Qingsheng

    2014-01-01

    Antifouling polymers have been proven to be vital to many biomedical applications such as medical implants, drug delivery, and biosensing. This review covers the major development of antifouling polymers in the last 2 decades, including the material chemistry, structural factors important to antifouling properties, and how to challenge or evaluate the antifouling performances. We then discuss the applications of antifouling polymers in nano/micro-biomedical applications in the form of nanoparticles, thin coatings for medical devices (e.g., artificial joint, catheter, wound dressing), and nano/microscale fibers. © 2014 Wiley Periodicals, Inc.

  13. Lifetime of Nano-Structured Black Silicon for Photovoltaic Applications

    DEFF Research Database (Denmark)

    Plakhotnyuk, Maksym; Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk;

    2016-01-01

    In this work, we present recent results of lifetime optimization for nano-structured black silicon and its photovoltaic applications. Black silicon nano-structures provide significant reduction of silicon surface reflection due to highly corrugated nanostructures with excellent light trapping......, respectively. This is promising for use of black silicon RIE nano-structuring in a solar cell process flow...

  14. Lifetime of Nano-Structured Black Silicon for Photovoltaic Applications

    DEFF Research Database (Denmark)

    Plakhotnyuk, Maksym; Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk;

    2016-01-01

    In this work, we present recent results of lifetime optimization for nano-structured black silicon and its photovoltaic applications. Black silicon nano-structures provide significant reduction of silicon surface reflection due to highly corrugated nanostructures with excellent light trapping pro......, respectively. This is promising for use of black silicon RIE nano-structuring in a solar cell process flow...

  15. Designing optimized nano textures for thin-film silicon solar cells

    NARCIS (Netherlands)

    Jäger, K.; Fischer, M.; Van Swaaij, R.A.C.M.M.; Zeman, M.

    2013-01-01

    Thin-film silicon solar cells (TFSSC), which can be manufactured from abundant materials solely, contain nano-textured interfaces that scatter the incident light. We present an approximate very fast algorithm that allows optimizing the surface morphology of two-dimensional nano-textured interfaces.

  16. Plasmonic excitation-assisted optical and electric enhancement in ultra-thin solar cells: the influence of nano-strip cross section

    Energy Technology Data Exchange (ETDEWEB)

    Sabaeian, Mohammad, E-mail: sabaiean@scu.ac.ir; Heydari, Mehdi; Ajamgard, Narges [Physics Department, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, 61357-43135 (Iran, Islamic Republic of)

    2015-08-15

    The effects of Ag nano-strips with triangle, rectangular and trapezoid cross sections on the optical absorption, generation rate, and short-circuit current density of ultra-thin solar cells were investigated. By putting the nano-strips as a grating structure on the top of the solar cells, the waveguide, surface plasmon polariton (SPP), and localized surface plasmon (LSP) modes, which are excited with the assistance of nano-strips, were evaluated in TE and TM polarizations. The results show, firstly, the TM modes are more influential than TE modes in optical and electrical properties enhancement of solar cell, because of plasmonic excitations in TM mode. Secondly, the trapezoid nano-strips reveal noticeable impact on the optical absorption, generation rate, and short-circuit current density enhancement than triangle and rectangular ones. In particular, the absorption of long wavelengths which is a challenge in ultra-thin solar cells is significantly improved by using Ag trapezoid nano-strips.

  17. Towards easily reproducible nano-structured SERS substrates

    DEFF Research Database (Denmark)

    Schmidt, Michael Stenbæk; Boisen, Anja; Hübner, Jörg

    2009-01-01

    , it is possible to narrowly control the parameters of the fabrication process to create silicon nano-pillars with controlled heights and spacing. The silicon nano-pillars are coated by thin films of silver and/or gold to create surfaces that greatly enhance the Raman effect. Surface enhanced Raman scattering...

  18. The fabrication and characterization of nano-SQUIDs based on Nb thin films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xixi; Liu, Xiaoyu; Wang, Hao; Chen, Lei, E-mail: leichen@mail.sim.ac.cn; Wang, Zhen

    2015-08-15

    Highlights: • We developed a nano-SQUID fabrication process starting from a high-quality thin film. • The fabricated nano-SQUIDs exhibited flux modulation depth up to 10.3% at 4.6 K. • The measured data agreed with the Ginzburg–Landau simulation. • We found that a small critical current <50 μA is important for a deep flux modulation. • The suggestions in improving the nano-SQUID’s performance were discussed. - Abstract: SQUIDs with nano-junctions (or nano-SQUIDs) are able to be miniaturized into nanoscale to measure a single Bohr magneton. Here, we reported the development of a fabrication process for Nb (niobium) nano-SQUIDs using the thin film deposition and the electron-beam lithography technology. The developed process started from a high-quality superconducting thin film so that it is compatible with a variety of film growing techniques. The as-fabricated nano-SQUIDs exhibited functional flux modulation depth up to 10.3% at 4.6 K, in agreement with the numerical simulation based on the Ginzburg–Landau equation. By further comparing the results from both experiments and simulations, we found that a small critical current below ∼50 μA played a leading role in order to obtain a decent flux-modulation depth for Nb nano-SQUIDs.

  19. Structural properties of dopping metallic impurities on CdS thin layers

    Directory of Open Access Journals (Sweden)

    S. Ghasemzadeh

    2016-12-01

    Full Text Available (Cu,Zn-dopped CdS thin layers were deposited on glass substrates by chemical bath deposition technique. The effects of the doping on the structural properties of CdS thin layers were studied by SEM and EDAX analysis. Hetero junction layers were produced with different nano structures and different fraction of voids and metallic ions.

  20. Structural properties of dopping metallic impurities on CdS thin layers

    OpenAIRE

    S. Ghasemzadeh; H. kangarlou

    2016-01-01

    (Cu,Zn)-dopped CdS thin layers were deposited on glass substrates by chemical bath deposition technique. The effects of the doping on the structural properties of CdS thin layers were studied by SEM and EDAX analysis. Hetero junction layers were produced with different nano structures and different fraction of voids and metallic ions.

  1. Compact micro/nano electrohydrodynamic patterning: using a thin conductive film and a patterned template.

    Science.gov (United States)

    Nazaripoor, Hadi; Koch, Charles R; Sadrzadeh, Mohtada; Bhattacharjee, Subir

    2016-01-28

    The influence of electrostatic heterogeneity on the electric-field-induced destabilization of thin ionic liquid (IL) films is investigated to control spatial ordering and to reduce the lateral dimension of structures forming on the films. Commonly used perfect dielectric (PD) films are replaced with ionic conductive films to reduce the lateral length scales to a sub-micron level in the EHD pattering process. The 3-D spatiotemporal evolution of a thin IL film interface under homogenous and heterogeneous electric fields is numerically simulated. Finite differences in the spatial directions using an adaptive time step ODE solver are used to solve the 2-D nonlinear thin film equation. The validity of our simulation technique is determined from close agreement between the simulation results of a PD film and the experimental results in the literature. Replacing the flat electrode with the patterned one is found to result in more compact and well-ordered structures particularly when an electrode with square block protrusions is used. This is attributed to better control of the characteristic spatial lengths by applying a heterogeneous electric field by patterned electrodes. The structure size in PD films is reduced by a factor of 4 when they are replaced with IL films, which results in nano-sized features with well-ordered patterns over the domain.

  2. The study of structural properties of carbon nanotubes decorated with NiFe₂O₄ nanoparticles and application of nano-composite thin film as H₂S gas sensor.

    Science.gov (United States)

    Hajihashemi, R; Rashidi, Ali M; Alaie, M; Mohammadzadeh, R; Izadi, N

    2014-11-01

    Nano-composite of multiwall carbon nanotube, decorated with NiFe2O4 nanoparticles (NiFe2O4-MWCNT), was synthesized using the sol-gel method. NiFe2O4-MWCNTs were characterized using different methods such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM). The average size of the crystallites is 23.93 nm. The values of the saturation magnetization (MS), coercivity (HC) and retentivity (MR) of NiFe2O4-MWCNTs are obtained as 15 emu g(-1), 21Oe and 5 emu g(-1), respectively. In this research, NiFe2O4-MWCNT thin films were prepared with the spin-coating method. These thin films were used as the H2S gas sensor. The results suggest the possibility of the utilization of NiFe2O4-MWCNT nano-composite, as the H2S detector. The sensor shows appropriate response towards 100 ppm of H2S at 300°C. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Influence of Oblique Angle Deposition on the Nano-structure and Characteristics of ZnO Thin Films Produced by Annealing of Zn Films

    Science.gov (United States)

    Savaloni, Hadi; Abbaszadeh, Neda

    2016-07-01

    Zinc oxide films were prepared using oblique angle deposition of Zn at four deposition angles of 0°, 30°, 45°, and 60° and subsequent annealing with the flow of oxygen. Structural characteristics of the films were obtained using atomic force microscopy and field emission scanning electron microscopy while their crystallography was investigated by x-ray diffraction analysis. The largest value of void fraction and the highest preferred orientation were obtained for the ZnO(101) diffraction line for the Zn film deposited at 45°. The former is explained in the published literature on the basis of rearrangement of atoms resulting from the diffusion or thermal vibration and the available crystallographic sites and surface energy on the substrate/growing film surface for relaxation of an adatom. Zn film anisotropy due to the bundling effect resulting from oblique angle deposition was examined by sheet resistivity measurements along x and y directions of the samples. Optical spectra of the samples were measured using both polarized light and unpolarized light from which optical constants were deduced. Both direct and indirect band gap energies were obtained and compared with the reported theoretical calculations. Our results are consistent with the experimental data in the literature; while they are larger than the theoretical reported values.

  4. Compatibility and optoelectronic of ZnSe nano crystalline thin film

    Institute of Scientific and Technical Information of China (English)

    Taj Muhammad Khan; Tayyaba BiBi

    2012-01-01

    We report the room temperature synthesis of zinc selenide (ZnSe) nano crystalline thin film on quartz by using a relatively simple and low cost closed space sublimation process (CSSP).The compatibility of the prepared thin films for optoelectronic applications was assessed by X-ray diffraction (XRD),atomic force microscope (AFM),scanning electron microscope (SEM),Raman spectroscopy,photoluminescence,and Fourier transform infrared spectroscopy (FT-IR).The XRD confirmed that the films were polycrystalline with the preferential orientation along the (111) plane corresponding to the cubic phase (2θ = 27.28°).The AFM indicated that the ZnSe film presented a smooth and compact morphology with RMS roughness 19.86 nm. The longitudinal optical phonon modes were observed at 247 cm-1 and 490 cm-1 attributed to the cubic structured ZnSe.The Zn-Se stretching band was confirmed by the FT-IR.The microstructure and compositional analysis was made with the SEM.The grain size,dislocation density,and strain calculated were co-related.All these properties manifested a good quality,high stability,finely adhesive,and closely packed structured ZnSe thin film for optoelectronic applications.

  5. Compatibility and optoelectronic of ZnSe nano crystalline thin film

    Science.gov (United States)

    Taj, Muhammad Khan; Tayyaba, BiBi

    2012-09-01

    We report the room temperature synthesis of zinc selenide (ZnSe) nano crystalline thin film on quartz by using a relatively simple and low cost closed space sublimation process (CSSP). The compatibility of the prepared thin films for optoelectronic applications was assessed by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), Raman spectroscopy, photoluminescence, and Fourier transform infrared spectroscopy (FT-IR). The XRD confirmed that the films were polycrystalline with the preferential orientation along the (111) plane corresponding to the cubic phase (2θ = 27.28°). The AFM indicated that the ZnSe film presented a smooth and compact morphology with RMS roughness 19.86 nm. The longitudinal optical phonon modes were observed at 247 cm-1 and 490 cm-1 attributed to the cubic structured ZnSe. The Zn—Se stretching band was confirmed by the FT-IR. The microstructure and compositional analysis was made with the SEM. The grain size, dislocation density, and strain calculated were co-related. All these properties manifested a good quality, high stability, finely adhesive, and closely packed structured ZnSe thin film for optoelectronic applications.

  6. Preparation of Nano-Particles (Pb,La)TiO3 Thin Films by Liquid Source Misted Chemical Deposition

    Institute of Scientific and Technical Information of China (English)

    张之圣; 曾建平; 李小图

    2004-01-01

    Nano-particles lanthanum-modified lead titanate (PLT) thin films are grown on Pt/Ti/SiO2/Si substrate by liquid source misted chemical deposition (LSMCD). PLT films are deposited for 4-8 times, and then annealed at various temperature. XRD and SEM show that the prepared films have good crystallization behavior and perovskite structure. The crystallite is about 60 nm. The deposition speed is 3 nm/min. This deposition method can exactly control stoichiometry ratios, doping concentration ratio and thickness of PLT thin films. The best annealing process is to bake at 300 ℃ for 10 min and anneal at 600 ℃ for 1 h.

  7. Advanced vectorial simulation of VCSELs with nano structures invited paper

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2009-01-01

    The single-mode properties and design issues of three vertical-cavity surface-emitting laser (VCSEL) structures incorporating nano structures are rigorously investigated. Nano structuring enables to deliver selective pumping or loss to the fundamental mode as well as stabilizing the output...... polarization state. Comparison of three vectorial simulation methods reveals that the modal expansion method is suitable for treating the nano structured VCSEL designs....

  8. Exploration of Wettability and Optical Aspects of ZnO Nano Thin Films Synthesized by Radio Frequency Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Kartik H. Patel

    2016-03-01

    Full Text Available This paper aims to explore structural, optical and wettabil‐ ity aspects of zinc oxide (ZnO nano thin films prepared by radio frequency (RF magnetron sputtering. The deposition time is varied from 10 to 50 minutes and sputtering pressure from 0.5 to 8.0 Pa. The increase of deposition time from 10 to 50 minutes leads to formation of a single (002 peak for ZnO films; (100, (101 and (110 peaks are not observed under these conditions. The intensity for (100, (002, (101 and (110 peaks decreases with a sputtering pressure value of 3.5 Pa and above. The optical transmis‐ sion and band gaps are measured by a UV-Vis-NIR spectrophotometer. The wettability and contact-angle hysteresis (CAH for deposited ZnO nano thin films are investigated for water, ethylene glycol, sunflower oil and formamide using a contact-angle goniometer.

  9. Superhydrophilicity and photocatalytic enhancement of titania nano thin films

    Science.gov (United States)

    Kazemi, M.; Mohammadizadeh, M. R.

    2011-02-01

    Anatase TiO2 thin films were prepared on glass substrates by the sol-gel dip coating method with TiCl4 as the Ti precursor and Tween 80 as a surfactant. XRD, AFM, and UV-Vis photospectroscopy experiments were used to analyze the structural and optical characteristics of the films. The influences of three different aging times on crystallinity, morphology, photocatalytic, superhydrophilicity behaviors, and size of the obtained TiO2 grains were investigated. With increasing the aging time, crystallite size of anatase structure and thickness of the films were increased. It was shown that in one of the samples, photocatalytic and superhydrophilic phenomena reach optimum, simultaneously. This could be very useful for self-cleaning application.

  10. Micro-and nano-structured conducting polymeric materials

    Institute of Scientific and Technical Information of China (English)

    LU Gewu; CHEN Feng'en; WU Xufeng; QU Liangti; ZHANG Jiaxin; SHI Gaoquan

    2005-01-01

    Conducting polymeric materials with micro-/nano-structures have potential applications in fabrication of various optical, electronic, sensing and electrochemical devices. This is mainly because these materials not only possess the characteristics of conducting polymers, but also have special functions based on their micro- or nano-structures. In this review, we summarize the recent work on "soft" and "hard" template-guided syntheses of micro-/nano-structured conducting polymers and open up the prospects of the main trends in this field.

  11. Fabrication of Anti-reflecting Si Nano-structures with Low Asp ect Ratio by Nano-sphere Litho-graphy Technique

    Institute of Scientific and Technical Information of China (English)

    Shenghua Sun; Peng Lu; Jun Xu; Ling Xu; Kunji Chen; Qimin Wang; Yuhua Zuo

    2013-01-01

    Nano-structured photon management is currently an interesting topic since it can enhance the optical absorption and reduce the surface reflection which will improve the performance of many kinds of optoelectronic devices, such as Si-based solar cells and light emitting diodes. Here, we report the fabrication of periodically nano-patterned Si structures by using polystyrene nano-sphere lithography technique. By changing the diameter of nano-spheres and the dry etching parameters, such as etching time and etching power, the morphologies of formed Si nano-structures can be well controlled as revealed by atomic force microscopy. A good broadband antireflection property has been achieved for the formed periodically nano-patterned Si structures though they have the low aspect ratio (<0.53). The reflection can be significantly reduced compared with that of flat Si substrate in a wavelength range from 400 nm to 1200 nm. The weighted mean reflection under the AM1.5 solar spectrum irradiation can be as low as 3.92% and the corresponding optical absorption is significantly improved, which indicates that the present Si periodic nano-structures can be used in Si-based thin film solar cells.

  12. Oxidation-Based Continuous Laser Writing in Vertical Nano-Crystalline Graphite Thin Films

    Science.gov (United States)

    Loisel, Loïc; Florea, Ileana; Cojocaru, Costel-Sorin; Tay, Beng Kang; Lebental, Bérengère

    2016-05-01

    Nano and femtosecond laser writing are becoming very popular techniques for patterning carbon-based materials, as they are single-step processes enabling the drawing of complex shapes without photoresist. However, pulsed laser writing requires costly laser sources and is known to cause damages to the surrounding material. By comparison, continuous-wave lasers are cheap, stable and provide energy at a more moderate rate. Here, we show that a continuous-wave laser may be used to pattern vertical nano-crystalline graphite thin films with very few macroscale defects. Moreover, a spatially resolved study of the impact of the annealing to the crystalline structure and to the oxygen ingress in the film is provided: amorphization, matter removal and high oxygen content at the center of the beam; sp2 clustering and low oxygen content at its periphery. These data strongly suggest that amorphization and matter removal are controlled by carbon oxidation. The simultaneous occurrence of oxidation and amorphization results in a unique evolution of the Raman spectra as a function of annealing time, with a decrease of the I(D)/I(G) values but an upshift of the G peak frequency.

  13. Nano-composite thermochromic thin films and their application in energy-efficient glazing

    Energy Technology Data Exchange (ETDEWEB)

    Saeli, Manfredi [Universita degli Studi di Palermo - Dipartimento di Progetto e Costruzione Edilizia (DPCE), Viale delle Scienze, 90128 Palermo (Italy); Piccirillo, Clara; Parkin, Ivan P.; Binions, Russell [University College London - Department of Chemistry - Christopher Ingold Laboratories, 20 Gordon Street, WC1H 0AJ London (United Kingdom); Ridley, Ian [Barlett School of Graduate Studies, University College London, Wates House, 22 Gordon Street, WC1H 0QB London (United Kingdom)

    2010-02-15

    A hybrid atmospheric pressure and aerosol-assisted chemical vapour deposition strategy is presented as a facile route for the production of vanadium dioxide nano-composite thin films. The effect of the inclusion of gold nanoparticles and the use of a surfactant molecule, tetraoctylammonium bromide, is discussed. The films were fully characterised using a wide variety of techniques, including scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV/vis/NIR spectroscopy. It is shown that micro-structural changes brought about by careful control of film growth conditions, and/or the use of surfactant, lead to an enhancement of thermochromic properties. Gold nanoparticle incorporation leads to a significant change in the colour of the films from a yellow-brown colour to a variety of greens and blues depending on the gold nanoparticle concentration. The films become more reflective in the infra-red with increased gold nanoparticle incorporation. Optical data are used in energy modelling studies to elucidate the film potential as an energy-saving coating in architectural glazing. The energy modelling results suggest that for warmer climates the thermochromic nano-composites investigated here lead to significant energy savings when compared with plain glass and other standard industry products. (author)

  14. Nano-Impact (Fatigue Characterization of As-Deposited Amorphous Nitinol Thin Film

    Directory of Open Access Journals (Sweden)

    Rehan Ahmed

    2012-08-01

    Full Text Available This paper presents nano-impact (low cycle fatigue behavior of as-deposited amorphous nitinol (TiNi thin film deposited on Si wafer. The nitinol film was 3.5 µm thick and was deposited by the sputtering process. Nano-impact tests were conducted to comprehend the localized fatigue performance and failure modes of thin film using a calibrated nano-indenter NanoTest™, equipped with standard diamond Berkovich and conical indenter in the load range of 0.5 mN to 100 mN. Each nano-impact test was conducted for a total of 1000 fatigue cycles. Depth sensing approach was adapted to understand the mechanisms of film failure. Based on the depth-time data and surface observations of films using atomic force microscope, it is concluded that the shape of the indenter test probe is critical in inducing the localized indentation stress and film failure. The measurement technique proposed in this paper can be used to optimize the design of nitinol thin films.

  15. Ferroelectric thin-film active sensors for structural health monitoring

    Science.gov (United States)

    Lin, Bin; Giurgiutiu, Victor; Yuan, Zheng; Liu, Jian; Chen, Chonglin; Jiang, Jiechao; Bhalla, Amar S.; Guo, Ruyan

    2007-04-01

    Piezoelectric wafer active sensors (PWAS) have been proven a valuable tool in structural health monitoring. Piezoelectric wafer active sensors are able to send and receive guided Lamb/Rayleigh waves that scan the structure and detect the presence of incipient cracks and structural damage. In-situ thin-film active sensor deposition can eliminate the bonding layer to improve the durability issue and reduce the acoustic impedance mismatch. Ferroelectric thin films have been shown to have piezoelectric properties that are close to those of single-crystal ferroelectrics but the fabrication of ferroelectric thin films on structural materials (steel, aluminum, titanium, etc.) has not been yet attempted. In this work, in-situ fabrication method of piezoelectric thin-film active sensors arrays was developed using the nano technology approach. Specification for the piezoelectric thin-film active sensors arrays was based on electro-mechanical-acoustical model. Ferroelectric BaTiO3 (BTO) thin films were successfully deposited on Ni tapes by pulsed laser deposition under the optimal synthesis conditions. Microstructural studies by X-ray diffractometer and transmission electron microscopy reveal that the as-grown BTO thin films have the nanopillar structures with an average size of approximately 80 nm in diameter and the good interface structures with no inter-diffusion or reaction. The dielectric and ferroelectric property measurements exhibit that the BTO films have a relatively large dielectric constant, a small dielectric loss, and an extremely large piezoelectric response with a symmetric hysteresis loop. The research objective is to develop the fabrication and optimum design of thin-film active sensor arrays for structural health monitoring applications. The short wavelengths of the micro phased arrays will permit the phased-array imaging of smaller parts and smaller damage than is currently not possible with existing technology.

  16. Cracks in nano-ceramic thin layers produced by laser treatments

    NARCIS (Netherlands)

    De Hosson, JTM; Teeuw, DHJ; Beltz, GE; Selinger, RLB; Kim, KS; Marder, MP

    1999-01-01

    Sol-gel derived thin nano-ceramic layers of TiO2 and Al2O3 are studied using scanning electron microscopy to reveal the microstructure and morphologies of the layers. The low-voltage scanning electron microscope with a field emission gun is equipped with an especially designed lens, where the specim

  17. Hybrid nanostructured thin-films by PLD for enhanced field emission performance for radiation micro-nano dosimetry applications

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, E., E-mail: maniphysics@gmail.com [UNESCO-UNISA AFNET in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), Materials Research Department, iThemba LABS–National Research Foundation (NRF), 1 Old Faure Road, Somerset West, PO Box 722, Western Cape (South Africa); Materials Science Group (MSG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India); Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India); Sree Balaji Medical College & Hospital (SBMCH), Bharath University, Chrompet, Chennai 600044 (India); Kennedy, J. [UNESCO-UNISA AFNET in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), Materials Research Department, iThemba LABS–National Research Foundation (NRF), 1 Old Faure Road, Somerset West, PO Box 722, Western Cape (South Africa); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Kavitha, G. [UNESCO-UNISA AFNET in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), Materials Research Department, iThemba LABS–National Research Foundation (NRF), 1 Old Faure Road, Somerset West, PO Box 722, Western Cape (South Africa); PG& Research Dept of Physics, AM Jain College Affiliated to University of Madras, Chennai 600114 (India); and others

    2015-10-25

    We report the observation of hybrid nanostructured thin-films such as diamond-like carbon (DLC) signature on the ZnO epitaxial thin-films grown onto the device silicon/quartz substrate by reactive pulsed laser deposition (r-PLD) under the argon–oxygen (Ar|O{sub 2}) ambient at 573 K. Undoped and Carbon (C) doped epitaxial ZnO thin-film layer formation is revealed by the accelerator based ion-beam analysis (IBA) technique of resonant Rutherford backscattering spectrometry (RRBS), glancing-incidence X-ray diffraction (GIXRD) pattern, micro-Raman spectroscopy (μ-RS) and field-emission (F-E) studies. The RRBS and GIXRD results show the deposition of epitaxial thin-films containing C into ZnO. The μ-RS technique is a standard nondestructive tool (NDT) for the characterization of crystalline, nano-crystalline, and amorphous carbons (a-C). As grown ZnO and C-doped ZnO thin-films μ-RS result reveal the doping effect of C-impurities that appear in the form of DLC evident from Raman peaks at 1357 and 1575 cm{sup −1} along with a wurtzite structure peak at 438 cm{sup −1} with E{sub 2}(h) phonon of ZnO. The electron transport F-E result shows the hybrid thin-films has high conductivity than the un-doped film. Fabricated hybrid nanostructured thin-films materials could be very useful for the emerging applications of micro-nano dosimetry. - Highlights: • Observation of hybrid nanostructured diamond-like carbon (DLC) on ZnO epitaxial thin-films at 573 K. • Carbon doped epitaxial ZnO thin-film layer formation is revealed by RRBS, Micro-Raman. • Field-emission (F-E) study. • DLC formation evident from Raman peaks at 1357 and 1575 cm{sup −1} along with a wurtzite structure peak of ZnO. • The electron transport F-E result shows the hybrid thin-film has high conductivity than the undoped thin-film.

  18. Evaluation of the Mechanical Properties of Multi-nano Layered Copper-Nickel Thin Film by the Dynamic-Nano Indentation Method

    Science.gov (United States)

    Choi, Yong

    2016-11-01

    The dynamic nano-indentation method was applied to study the effect of interface moving behavior with heat treatment on the nano-mechanical properties of multi-nano-layered copper-nickel thin film. Layer-by-layer depositions of copper and nickel of nano-sized thickness were prepared by two-step pulse electro-deposition in a modified copper-nickel sulfate bath at 25°C. The multi-layered copper-nickel thin sheet was composed of a 20-nm-thick copper-rich nickel phase, and a 25-nm-thick nickel-rich copper phase. Thermal vacuum annealing influenced the interface morphology between copper and nickel nano-layers. Inter-diffusion mainly occurred after annealing at 500°C for 6 h. The interface disappeared after annealing at 600°C to form a completely solid solution. Thermal annealing reduced the nano-hardness and elastic recovery. The average nano-hardness of the multi-layered nano-copper-nickel thin film for the specimens of as-received, 300°C, 500°C and 600°C were 7.9 Gpa, 6.1 Gpa, 4.7 Gpa and 3.0 GPa, respectively. The elastic stiffness was 15.77 × 104 Nm-1 for the as-received specimen, which finally became 2.98 × 104 Nm-1 for the specimen after annealing at 600°C for 6 h.

  19. Nano-Structured Proton Exchange Membrane for Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Wu Chien-Suen; Lin Fan-Yen; Chu Peter P

    2005-01-01

    @@ 1Introduction Nano-structured materials are characterized by long range ordering of the nano-dimensioned quantum dot units. They have been found to deliver substantially different (electric, optical, magnetic and physical) properties from that of the bulk. The differences are mainly due to the increases of surface charge with large fraction of grain boundaries, and the periodical potential field created by the ordered nano-domains. Specifically,the issues considered in "nano ionics" are the degree of interaction, the charge distribution on the interfaces where they become obvious in ionic properties and thermodynamics such as mobility of charge carriers. Major efforts in this direction are focused on:

  20. Study on micro-structure and morphological evolution of Fe/Pt nano-magnetic film.

    Science.gov (United States)

    Ishiguro, S; Ju, D Y; Ogatsu, R; Nakano, T

    2011-10-01

    One of the vertical magnetic recordings medium materials of the hard disk drive (HDD) is a Fe/Pt thin film. The development of ultra-high density magnetic recording medium in next generation is expected the magnetic disks such as HDD with capacity enlargement of the data. In order to study effectiveness of the proposed sputtering method, we evaluated micro structure, magnetic and the mechanical properties of a Fe/Pt thin film by some sputtering process conditions. From research results, effect sputtering conditions on micro-structure and mechanical properties of Fe/Pt nano film are verified.

  1. Fabrication and characteristics of magnetic field sensors based on nano-polysilicon thin-film transistors

    Institute of Scientific and Technical Information of China (English)

    Zhao Xiaofeng; Wen Dianzhong; Zhuang Cuicui; Cao Jingya; Wang Zhiqiang

    2013-01-01

    A magnetic field sensor based on nano-polysilicon thin films transistors (TFTs) with Hall probes is proposed.The magnetic field sensors are fabricated on 〈100〉 orientation high resistivity (ρ > 500 Ω·cm) silicon substrates by using CMOS technology,which adopt nano-polysilicon thin films with thicknesses of 90 nm and heterojunction interfaces between the nano-polysilicon thin films and the high resistivity silicon substrates as the sensing layers.The experimental results show that when VDS =5.0 V,the magnetic sensitivities of magnetic field sensors based on nano-polysilicon TFTs with length-width ratios of 160 μm/80 μm,320 μm/80 μm and 480 μm/80μm are 78 mV/T,55 mV/T and 34 mV/T,respectively.Under the same conditions,the magnetic sensitivity of the obtained magnetic field sensor is significantly improved in comparison with a Hall magnetic field sensor adopting silicon as the sensing layers.

  2. Buckling of Thin Films in Nano-Scale

    Directory of Open Access Journals (Sweden)

    Li L.A.

    2010-06-01

    Full Text Available Investigation of thin film buckling is important for life prediction of MEMS device which are damaged mainly by the delamination and buckling of thin films. In this paper the mechanical and thermal properties of compressed thin film titanium films with 150 nm thickness deposited on an organic glass substrate under mechanical and thermal loads were measured and characterized. In order to simulate the thin films which subjected to compound loads and the buckle modes the external uniaxial compression and thermal loading were subjected to the specimen by the symmetric loading device and the electrical film in this experiment. The temperature of the thin film deposited on substrate was measured using thermoelectric couple. The range of temperature accords with the temperature range of the MEMS. It is found that the size and number of the delamination and buckling of the film are depended upon the pre-fixed mechanical loading and thermal temperature. The thermal transient conduction and thermal stability of the film and substrate was studied with finite element method.

  3. Buckling of Thin Films in Nano-Scale

    Science.gov (United States)

    Wang, S.; Jia, H. K.; Sun, J.; Ren, X. N.; Li, L. A.

    2010-06-01

    Investigation of thin film buckling is important for life prediction of MEMS device which are damaged mainly by the delamination and buckling of thin films. In this paper the mechanical and thermal properties of compressed thin film titanium films with 150 nm thickness deposited on an organic glass substrate under mechanical and thermal loads were measured and characterized. In order to simulate the thin films which subjected to compound loads and the buckle modes the external uniaxial compression and thermal loading were subjected to the specimen by the symmetric loading device and the electrical film in this experiment. The temperature of the thin film deposited on substrate was measured using thermoelectric couple. The range of temperature accords with the temperature range of the MEMS. It is found that the size and number of the delamination and buckling of the film are depended upon the pre-fixed mechanical loading and thermal temperature. The thermal transient conduction and thermal stability of the film and substrate was studied with finite element method.

  4. Fabrication of semi-transparent superoleophobic thin film from fabrics and nanoparticle-based hierarchical structure

    OpenAIRE

    Nishizawa S.; Shiratori S.

    2013-01-01

    Superoleophobic thin films have many potential applications including fluid transfer, fluid power systems, stain resistant and antifouling materials, and microfluidics among others. Transparency is also desired with superhydrophobicity for their numerous applications; however transparency and oleophobicity are almost incompatible relationship with each other in the point of surface structure. Because oleophobicity required rougher structure at nano-micro scale than hydrophobicity, and these r...

  5. Phonon transport across nano-scale curved thin films

    Science.gov (United States)

    Mansoor, Saad B.; Yilbas, Bekir S.

    2016-12-01

    Phonon transport across the curve thin silicon film due to temperature disturbance at film edges is examined. The equation for radiative transport is considered via incorporating Boltzmann transport equation for the energy transfer. The effect of the thin film curvature on phonon transport characteristics is assessed. In the analysis, the film arc length along the film centerline is considered to be constant and the film arc angle is varied to obtain various film curvatures. Equivalent equilibrium temperature is introduced to assess the phonon intensity distribution inside the curved thin film. It is found that equivalent equilibrium temperature decay along the arc length is sharper than that of in the radial direction, which is more pronounced in the region close to the film inner radius. Reducing film arc angle increases the film curvature; in which case, phonon intensity decay becomes sharp in the close region of the high temperature edge. Equivalent equilibrium temperature demonstrates non-symmetric distribution along the radial direction, which is more pronounced in the near region of the high temperature edge.

  6. Phonon transport across nano-scale curved thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mansoor, Saad B.; Yilbas, Bekir S., E-mail: bsyilbas@kfupm.edu.sa

    2016-12-15

    Phonon transport across the curve thin silicon film due to temperature disturbance at film edges is examined. The equation for radiative transport is considered via incorporating Boltzmann transport equation for the energy transfer. The effect of the thin film curvature on phonon transport characteristics is assessed. In the analysis, the film arc length along the film centerline is considered to be constant and the film arc angle is varied to obtain various film curvatures. Equivalent equilibrium temperature is introduced to assess the phonon intensity distribution inside the curved thin film. It is found that equivalent equilibrium temperature decay along the arc length is sharper than that of in the radial direction, which is more pronounced in the region close to the film inner radius. Reducing film arc angle increases the film curvature; in which case, phonon intensity decay becomes sharp in the close region of the high temperature edge. Equivalent equilibrium temperature demonstrates non-symmetric distribution along the radial direction, which is more pronounced in the near region of the high temperature edge.

  7. Electrospinning for nano- to mesoscale photonic structures

    Directory of Open Access Journals (Sweden)

    Skinner Jack L.

    2017-08-01

    Full Text Available The fabrication of photonic and electronic structures and devices has directed the manufacturing industry for the last 50 years. Currently, the majority of small-scale photonic devices are created by traditional microfabrication techniques that create features by processes such as lithography and electron or ion beam direct writing. Microfabrication techniques are often expensive and slow. In contrast, the use of electrospinning (ES in the fabrication of micro- and nano-scale devices for the manipulation of photons and electrons provides a relatively simple and economic viable alternative. ES involves the delivery of a polymer solution to a capillary held at a high voltage relative to the fiber deposition surface. Electrostatic force developed between the collection plate and the polymer promotes fiber deposition onto the collection plate. Issues with ES fabrication exist primarily due to an instability region that exists between the capillary and collection plate and is characterized by chaotic motion of the depositing polymer fiber. Material limitations to ES also exist; not all polymers of interest are amenable to the ES process due to process dependencies on molecular weight and chain entanglement or incompatibility with other polymers and overall process compatibility. Passive and active electronic and photonic fibers fabricated through the ES have great potential for use in light generation and collection in optical and electronic structures/devices. ES produces fiber devices that can be combined with inorganic, metallic, biological, or organic materials for novel device design. Synergistic material selection and post-processing techniques are also utilized for broad-ranging applications of organic nanofibers that span from biological to electronic, photovoltaic, or photonic. As the ability to electrospin optically and/or electronically active materials in a controlled manner continues to improve, the complexity and diversity of devices

  8. Conformal nano-thin modified polyelectrolyte coatings for encapsulation of cells.

    Science.gov (United States)

    Granicka, L H; Antosiak-Iwańska, M; Godlewska, E; Strawski, M; Szklarczyk, M; Maranowski, B; Kowalewski, C; Wiśniewsk, J

    2011-10-01

    Encapsulation of cells in polymeric shells allows for separation of biological material from produced factors, which may find biotechnological and biomedical applications. Human T-lymphocyte cell line Jurkat as well as rat pancreatic islets were encapsulated using LbL technique within shells of polyelectrolyte modified by incorporation of biotin complexed with avidin to improve cell coating and to create the potential ability to elicit specific biochemical responses. The coating with nano-thin modified shells allowed for maintenance of the evaluated cells' integrity and viability during the 8-day culture. The different PE impact may be observed on different biological materials. The islets exhibited lower mitochondrial activity than the Jurkat cells. Nevertheless, coating of cells with polyelectrolyte modified membrane allowed for functioning of both model cell types: 10 μm leukemia cells or 150 μm islets during the culture. Applied membranes maintained the molecular structure during the culture period. The conclusion is that applied modified membrane conformation may be recommended for coating shells for biomedical purposes.

  9. Electrodeposition and characterization of nano-structured black nickel thin films%纳米结构黑镍薄膜的电沉积制备及其电化学行为

    Institute of Scientific and Technical Information of China (English)

    李建梅; 蔡超; 宋利晓; 李劲风; 张昭; 薛敏钊; 刘燕刚

    2013-01-01

    The electrodeposition and characterization of nano-structured black nickel coatings were presented. The influences of bath pH, electrodeposition time, stirring speed, temperature and current density on the color and microstructure of the electrodeposited nickel film were investigated through naked eyes, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Meanwhile, the corrosion resistance of the optimized black nickel film was evaluated by the polarization measurement and electrochemical impedance spectroscopy (EIS) in the neutral 3.5% NaCl solution. The results show that the color of the electrodeposited nickel film was highly dependent on the above technological parameters. The operating parameters were optimized mainly according to the color. The optimized black nickel film possesses nano-structure with an average grain diameter of about 50 nm. It also exhibits enhanced corrosion resistance when compared with white nickel coatings electrdodeposited under the same condition except the variation of the electroplating current density.%采用电沉积方法制备具有整体纳米结构的黑镍镀层,并通过肉眼观察结合扫描电镜、X射线衍射等测试技术研究电沉积过程中的主要参数(电解液pH、搅拌速度、制备温度及电流密度)对镀层颜色及整体微观结构的影响。进一步采用动电位极化及电化学阻抗等电化学测量技术研究黑镍镀层在中性3.5%NaCl溶液中的腐蚀行为及腐蚀机理。结果表明:黑镍镀层的颜色变化趋势决定于电沉积制备参数的选择;通过优化本工艺制备的黑镍镀层平均粒径约为50 nm。对比了近似条件下制备的光亮镍镀层,发现黑镍镀层在耐蚀性方面具有较大优势。

  10. Crystal structure of fiber structured pentacene thin films

    OpenAIRE

    2007-01-01

    This PhD thesis presents a technique based on the grazing incidence crystal truncation rod (GI-CTR) X-ray diffraction method used to solve the crystal structure of substrate induced fiber structured organic thin films. The crystal structures of pentacene thin films grown on technologically relevant gate dielectric substrates are reported. It is widely recognized, that the intrinsic charge transport properties in organic thin film transistors (OTFTs) depend strongly on the crystal structur...

  11. Manufacture of Nano Structures in Polymer Material

    DEFF Research Database (Denmark)

    Hansen, Hans Nørgaard; Pedersen, H.C.; Staun, Jacob

    2003-01-01

    The incorporation of micro and nano technology into the products of the future is an area of increasing interest. The ideas for new products based on this technology often take their starting point in specific scientific fields whereas the subsequent design and product development not necessarily...... is based on a systematic approach including manufacturing processes and production system capabilities. The process chain associated with micro and nano injection moulding usually comprises silicon or photoresist mastering, electroforming and polymer processing. Additionally, if the produced polymer...

  12. Investigation of superhydrophilic mechanism of titania nano layer thin film—Silica and indium oxide dopant effect

    Indian Academy of Sciences (India)

    Akbar Eshaghi; Ameneh Eshaghi

    2012-04-01

    In this paper, TiO2–SiO2–In2O3 nano layer thin films were deposited on glass substrate using sol–gel dip coating method. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements were used to evaluate chemical structure, surface composition, hydroxyl group contents and superhydrophilicity of titania films. FTIR result indicated that Si–O–Si, Si–O–Ti and Ti–O–Ti bands formed in TiO2–SiO2–In2O3 sample. According to XPS, the hydroxyl content for TiO2, TiO2–SiO2 and TiO2–SiO2–In2O3 films was calculated as 11.6, 17.1 and 20.7%, respectively. The water contact angle measurements indicated that silica and indium oxide dopant improved the superhydrophilicity of titania nano film surface especially in a dark place. The enhanced superhydrophilicity can be related to the generation of surface acidity on the titania nano film surfaces. In the present state, superhydrophilicity is induced by the simultaneous presence of both Lewis and Bronsted sites.

  13. Plasmonic excitation-assisted optical and electric enhancement in ultra-thin solar cells: the influence of nano-strip cross section

    Directory of Open Access Journals (Sweden)

    Mohammad Sabaeian

    2015-08-01

    Full Text Available The effects of Ag nano-strips with triangle, rectangular and trapezoid cross sections on the optical absorption, generation rate, and short-circuit current density of ultra-thin solar cells were investigated. By putting the nano-strips as a grating structure on the top of the solar cells, the waveguide, surface plasmon polariton (SPP, and localized surface plasmon (LSP modes, which are excited with the assistance of nano-strips, were evaluated in TE and TM polarizations. The results show, firstly, the TM modes are more influential than TE modes in optical and electrical properties enhancement of solar cell, because of plasmonic excitations in TM mode. Secondly, the trapezoid nano-strips reveal noticeable impact on the optical absorption, generation rate, and short-circuit current density enhancement than triangle and rectangular ones. In particular, the absorption of long wavelengths which is a challenge in ultra-thin solar cells is significantly improved by using Ag trapezoid nano-strips.

  14. Heteroepitaxial growth of Ge on compliant strained nano-structured Si lines and dots on (001) silicon on insulator substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zaumseil, Peter, E-mail: zaumseil@ihp-microelectronics.com [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Yamamoto, Yuji; Schubert, Markus Andreas [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Schroeder, Thomas [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Brandenburgische Technische Universität Cottbus, Konrad-Zuse-Str.1, Cottbus, 03046 (Germany); Tillack, Bernd [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Technische Universität Berlin, HFT4, Einsteinufer 25, 10587 Berlin (Germany)

    2014-04-30

    On the way to integrate lattice mismatched semiconductors on Si(001) we studied the Ge/Si heterosystem with the aim of a misfit dislocation free deposition that offers the vision to integrate defect-free alternative semiconductor structures on Si. Periodic Ge nano-structures (dots and lines) were selectively grown by chemical vapor deposition on Si nano-islands on silicon on insulator substrate with a thin (about 10 nm) SiGe buffer layer between Si and Ge. The strain state of the structures was measured by grazing incidence and specular diffraction using laboratory-based X-ray diffraction technique. The SiGe improves the compliance of the Si compared to direct Ge deposition, prevents plastic relaxation during growth, and allows elastic relaxation before Ge is deposited on top. As a result, an epitaxial growth of Ge on Si fully free of misfit dislocations was achieved. - Highlights: • Realization of nano-structured Si islands (dots and lines) on silicon on insulator substrate • Selective Ge epitaxy on nano-structured periodic Si islands with thin SiGe buffer • Strain characterization of Ge nano-structures by X-ray diffraction • Ge heteroepitaxy on Si without misfit dislocation confirmed by transmission electron microscopy.

  15. Optical properties of polysiloxane hybrid thin films containing nano-sized Ag-As-Se chalcogenide clusters

    Science.gov (United States)

    Zha, Congji; Osvath, Peter; Wilson, Gerry; Launikonis, Anton

    2009-02-01

    Chalcogenide glasses are attractive for all-optical signal processing due to their outstanding optical properties, including large optical nonlinearity, a high refractive index and high photosensitivity. In device fabrication, a challenge lies in the difficulty of obtaining thin films with a high stability and good uniformity. In this paper, optical thin films containing nano-sized chalcogenide clusters in polysiloxane matrices are fabricated by a modified plasma deposition process. The optical absorption and luminescence emission properties of the hybrid thin films were characterized by UV-Vis-NIR and fluorescence spectroscopy. Luminescent emission from Ag-As-Se nano-sized clusters was observed for the first time in these nano-hybrid thin films, and the mechanism was discussed.

  16. Transformation from amorphous to nano-crystalline SiC thin films prepared by HWCVD technique without hydrogen dilution

    Indian Academy of Sciences (India)

    F Shariatmadar Tehrani

    2015-09-01

    Silicon carbide (SiC) thin films were deposited on Si(111) by the hot wire chemical vapour deposition (HWCVD) technique using silane (SiH4) and methane (CH4) gases without hydrogen dilution. The effects of SiH4 to CH4 gas flow ratio (R) on the structural properties, chemical composition and photoluminescence (PL) properties of the films deposited at the different gas flow ratios were investigated and compared. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra revealed a structural transition from amorphous SiC to cubic nano-crystalline SiC films with the increase in the gas flow ratio. Raman scattering confirmed the multi-phased nature of the films. Auger electron spectroscopy showed that the carbon incorporation in the film structure was strongly dependent on the gas flow ratio. A similar broad visible room-temperature PL with two peaks was observed for all SiC films. The main PL emission was correlated to the band to band transition in uniform a-SiC phase and the other lower energy emission was related to the confined a-Si : H clusters in a-SiC matrix. SiC nano-crystallites exhibit no significant contribution to the radiative recombination.

  17. PREFACE: International Conference on Structural Nano Composites (NANOSTRUC 2012)

    Science.gov (United States)

    Njuguna, James

    2012-09-01

    Dear Colleagues It is a great pleasure to welcome you to NanoStruc2012 at Cranfield University. The purpose of the 2012 International Conference on Structural Nano Composites (NanoStruc2012) is to promote activities in various areas of materials and structures by providing a forum for exchange of ideas, presentation of technical achievements and discussion of future directions. NanoStruc brings together an international community of experts to discuss the state-of-the-art, new research results, perspectives of future developments, and innovative applications relevant to structural materials, engineering structures, nanocomposites, modelling and simulations, and their related application areas. The conference is split in 7 panel sessions, Metallic Nanocomposites and Coatings, Silica based Nanocomposites, safty of Nanomaterials, Carboin based Nanocomposites, Multscale Modelling, Bio materials and Application of Nanomaterials. All accepted Papers will be published in the IOP Conference Series: Materials Science and Engineering (MSE), and included in the NanoStruc online digital library. The abstracts will be indexed in Scopus, Compedex, Inspec, INIS (International Nuclear Information System), Chemical Abstracts, NASA Astrophysics Data System and Polymer Library. Before ending this message, I would like to acknowledge the hard work, professional skills and efficiency of the team which ensured the general organisation. As a conclusion, I would like to Welcome you to the Nanostruc2012 and wish you a stimulating Conference and a wonderful time. On behalf of the scientific committee, Signature James Njuguna Conference Chair The PDF of this preface also contains committee listings and associates logos.

  18. Strain and structure in nano Ag films deposited on Au: Molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Zientarski, Tomasz, E-mail: martom@dyzio.umcs.lublin.pl [Department for the Modelling of Physico-Chemical Processes, Maria Curie-Skłodowska University, ul. Gliniana 33, 20-614 Lublin (Poland); Chocyk, Dariusz [Department of Applied Physics, Lublin University of Technology, ul. Nadbystrzycka 38, 20-618 Lublin (Poland)

    2014-07-01

    Molecular dynamics simulations are applied to analyze the stress and structure of nano Ag thin films deposited on the Au substrate. The interactions in the system are described by the embedded atom method. The kinematical theory of scattering is employed to identify the structure obtained from simulations data. Results shows that the silver layers are adjusted to the crystalline lattice of the gold buffer layers, and during the deposition process only compressive stress is observed. In all the cases the distribution of stress does not depend on temperature.

  19. Optical and Electrical Investigation of ZnO Nano-Wire Array to Micro-Flower from Hierarchical Nano-Rose Structures.

    Science.gov (United States)

    Pal, Kaushik; Zhan, Bihong; Ma, Xiao; Wang, Guoping; Schirhagl, Romana; Murgasen, Priya

    2016-01-01

    We have demonstrated a simple solvo-chemical and solvo-thermal route to design various nano-structures growth of zinc oxide (ZnO). The shapes and morphologies can be easily controlled by using different ambient conditions. We successfully fabricated ZnO nano-wires array on ITO substrate. Those nano-wire array center gradually formed micro-flower like structure evolved in this solvo-chemical route. This novel synthesis happened under cationic surfactant CTAB in the solution helps to form hierarchical structures of ZnO. The length of nano-wire is around 2.0 µm, which formed micro-flower diameter 5.0 µm. Micro-flowers were scratched out from ITO substrate thin film and annealed at 650 °C in electric oven for 1 hour, eventually this micro-flower transformed to novel nano-rose structure confirmed by electron microscopic study. Synthesized nano-rose diameter was around 730 nm. Moreover, we found a drastic change of dielectric behavior and DC conductivity of ZnO nanostructures depending on geometry regulated by the duration of preparation. Interestingly enough, optical and electrical properties also changed due to different crystalline structure formation. The dielectric constant is higher at 7.5 also high threshold voltages at 4 V, corresponds to nano-wires array with micro-flower system. A detail dielectric analysis of one step behavior of broad single relaxation peak was obtained only shows the normal dispersion in this system from 1000 kHz to 10 MHz. While less dielectric constant 1.7 and low threshold voltage 1 V, investigated nano-wires with micro-flower, then nano-rose transition appeared in two step behaviors of double relaxations phenomenon appeared one at low frequency and other at higher frequency region. Besides, I~V response characteristics is new idea about different breakdown voltages and bi-stable DC switching capability. Our work demonstrates the possibility of a fast novel synthesis route using a Solvo-chemical process for this type of nanomaterials

  20. A nano-grid structure made of perovskite SrTiO3 nanowires for efficient electron transport layers in inverted polymer solar cells.

    Science.gov (United States)

    Kim, Jeong Won; Suh, Yo-han; Lee, Chang-Lyoul; Kim, Yong Seok; Kim, Won Bae

    2015-03-14

    A nano-grid structure of perovskite SrTiO3 NWs is developed for a novel electron transport layer in inverted polymer solar cells. Due to the excellent charge transporting properties of the SrTiO3 nano-grid structure, the device employing this nanostructure showed ∼32% enhanced photovoltaic performance, compared to the solar cell using a TiO2 thin film.

  1. Efficient gas sensitivity in mixed bismuth ferrite micro (cubes) and nano (plates) structures

    Energy Technology Data Exchange (ETDEWEB)

    Waghmare, Shivaji D.; Jadhav, Vijaykumar V.; Gore, Shaym K. [Center for Nanomaterials and Energy Devices, School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, Maharashtra (India); Yoon, Seog-Joon; Ambade, Swapnil B. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Seoul 133-1791 (Korea, Republic of); Lokhande, B.J. [Department of Physics, Solapur University, Solapur (India); Mane, Rajaram S., E-mail: rsmane_2000@yahoo.com [Center for Nanomaterials and Energy Devices, School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, Maharashtra (India); Han, Sung-Hwan, E-mail: shhan@hanyang.ac.kr [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Seoul 133-1791 (Korea, Republic of)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Micro (cubes) structure embedded in nano (plates) of bismuth ferrite was prepared by a chemical method. ► These structures were characterized by XRD and SEM. ► LPG, CO{sub 2} and NH{sub 4} gases were exposed. ► Properties related to gas sensors were measured and reported. -- Abstract: Mixed micro (cubes) and nano (plates) structures of bismuth ferrite (BFO) have been synthesized by a simple and cost-effective wet-chemical method. Structural, morphological and phase confirmation characteristics are measured using X-ray diffraction, field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis techniques. The digital FE-SEM photo-images of BFO sample confirmed an incubation of discrete micro-cubes into thin and regularly placed large number of nano-plates. The bismuth ferrite, with mixed structures, films show considerable performance when used in liquefied petroleum (LPG), carbon dioxide (CO{sub 2}) and ammonium (NH{sub 3}) gas sensors application. Different chemical entities in LPG have made it more efficient with higher sensitivity, recovery and response times compared to CO{sub 2} and NH{sub 3} gases. Furthermore, effect of palladium surface treatment on the gas sensitivity and the charge transfer resistances of BFO mixed structures is investigated and reported.

  2. Plasma breaking of thin films into nano-sized catalysts for carbon nanotube synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Gao, J.S.; Umeda, K.; Uchino, K.; Nakashima, H.; Muraoka, K

    2003-07-15

    Iron thin films deposited by pulse laser deposition (PLD) were broken into uniform nano-sized catalysts by plasma bombardment for carbon nanotube (CNT) synthesis. Size distributions of broken catalysts were obtained in terms of plasma discharge conditions. Vertically arranged high-density (10{sup 13} per m{sup 2}) CNTs were synthesized using microwave plasma chemical vapor deposition (MP-CVD) system and the gas mixture of N{sub 2} and CH{sub 4} on optimally broken catalysts with few carbonaceous particles on a large area Si substrate. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy (RS) were used to evaluate the obtained CNTs.

  3. Ambipolar organic thin-film transistor-based nano-floating-gate nonvolatile memory

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jinhua; Wang, Wei, E-mail: wwei99@jlu.edu.cn; Ying, Jun; Xie, Wenfa [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

    2014-01-06

    An ambipolar organic thin-film transistor-based nano-floating-gate nonvolatile memory was demonstrated, with discrete distributed gold nanoparticles, tetratetracontane (TTC), pentacene as the floating-gate layer, tunneling layer, and active layer, respectively. The electron traps at the TTC/pentacene interface were significantly suppressed, which resulted in an ambipolar operation in present memory. As both electrons and holes were supplied in the channel and trapped in the floating-gate by programming/erasing operations, respectively, i.e., one type of charge carriers was used to overwrite the other, trapped, one, a large memory window, extending on both sides of the initial threshold voltage, was realized.

  4. Antimicrobial properties of silver-doped hydroxyapatite nano-powders and thin films

    Science.gov (United States)

    Sygnatowicz, Michael; Keyshar, Kunttal; Tiwari, Ashutosh

    2010-07-01

    Silver-doped hydroxyapatite nanopowders were prepared using a solution based sol-gel method and thoroughly characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Antibacterial tests showed silver-doped HAP powders prevented the growth and reproduction of bacteria. Silver-doped HAP powders were pressed into pellets and on these pellets a pulsed laser deposition (PLD) technique was employed to grow amorphous and crystalline thin films on sapphire substrates. Crystalline films had silver nano-particles present within the HAP matrix. Film stability tests showed crystalline films to be far more stable in prolonged solution submersion than their amorphous counterparts.

  5. Surface Nano-Structuring by Adsorption and Chemical Reactions

    OpenAIRE

    Ken-ichi Tanaka

    2010-01-01

    Nano-structuring of the surface caused by adsorption of molecules or atoms and by the reaction of surface atoms with adsorbed species are reviewed from a chemistry viewpoint. Self-assembly of adsorbed species is markedly influenced by weak mutual interactions and the local strain of the surface induced by the adsorption. Nano-structuring taking place on the surface is well explained by the notion of a quasi-molecule provided by the reaction of surface atoms with adsorbed species. Self-assembl...

  6. CdTe nano-structures for photovoltaic devices

    OpenAIRE

    Corregidor, V.; Alves, L. C.; FRANCO, N.; Barreiros, Maria Alexandra; Sochinskii, N. V.; Alves, E

    2013-01-01

    CdTe nano-structures with diameter of ∼100 nm and variable length (200–600 nm) were fabricated on glass substrates covered with conductive buffer layers such as NiCr, ZAO (ZnO:Al2O3 + Ta2O5) or TiPd alloys. The fabrication process consisted of the starting vapour deposition of metal catalyst dropped layer followed by the isothermal catalyst-prompted vapour growth of CdTe nano-structured layer of controllable shape and surface filling. The effect of buffer layers on the crystallographic orient...

  7. Tolerance Verification of Micro and Nano Structures on Polycarbonate Substrates

    DEFF Research Database (Denmark)

    Gasparin, Stefania; Tosello, Guido; Hansen, Hans Nørgaard

    2010-01-01

    Micro and nano structures are an increasing challenge in terms of tolerance verification and process quality control: smaller dimensions led to a smaller tolerance zone to be evaluated. This paper focuses on the verification of CD, DVD and HD-DVD nanoscale features. CD tolerance features are defi......Micro and nano structures are an increasing challenge in terms of tolerance verification and process quality control: smaller dimensions led to a smaller tolerance zone to be evaluated. This paper focuses on the verification of CD, DVD and HD-DVD nanoscale features. CD tolerance features...

  8. The NanoChitosan thin film: a new portable support for immobilization of Acid phosphatase

    Directory of Open Access Journals (Sweden)

    Mohammad Fahiminiaa

    2016-12-01

    Full Text Available Immobilization can enhance the economic value of enzymes and helps reusing and improves their stability. For the first time, acid phosphatase from Phaseolus vulgaris seeds was immobilized on chitosan nanoparticles thin films (CSNPs-TFs. Maximum immobilization yield of NanoChitosan thin films with 1×1cm dimensionand 3±0.1 mg (one block was ∼84%. In comparison with free enzyme, the activity of acid phosphatase was decreased 16% after immobilization. Immobilized acid phosphatase retained 51 % activity upon storage for 90 days at 4 °C and could be reused for 20 cycles with more than 88 % activity retention. The present study, immobilization of acid phosphatase on CSNPs-TF, is a new promising method which could explore a new biocompatible and eco-friendly material in enzyme immobilization, water treatment application as well as new adsorbent for occupational and environmental monitoring.

  9. Structure transition of nano-titania during calcination

    Institute of Scientific and Technical Information of China (English)

    李国华; 王大伟; 徐铸德; 陈卫祥

    2003-01-01

    In order to study the structure transition during calcination, nano-titania powders prepared by hydrolyzing precipitation approach and calcined at 300, 400, 500, 600 and 700 ℃ were characterized by XRD, TEM and electron diffraction(ED), respectively. The results show that titania powders calcined below 500 ℃ are almost composed of anatase, rutile appears below 500 ℃ and its ratio increases gradually with increase of calcin temperature;nano-titania particles are smaller than 40 nm mostly and the dispersion is related to calcining temperature; the interplanar distances of nano-anatase single crystalline change gradually when calcing temperature increases to 500 ℃; so do that of nano-rutile single crystalline when calcining temperature charges from 600 to 700 ℃. The conclusions can be drawn that the temperature of transformation from anatase to rutile is below 500 ℃ and the process carries on gradually. Both inter-planar distances and the structure of nano-titania transform gradually with increasing calcing temperature.

  10. Theoretical comparison of optical and electronic properties of uniformly and randomly arranged nano-porous ultra-thin layers.

    Science.gov (United States)

    Hubarevich, Aliaksandr; Marus, Mikita; Fan, Weijun; Smirnov, Aliaksandr; Sun, Xiao Wei; Wang, Hong

    2015-07-13

    The theoretical comparison of optical and electronic properties of aluminum and silver nano-porous ultra-thin layers in terms of the arrangement and size of the pores was presented. The uniform nano-porous layers exhibit a slightly higher average transmittance (up to 10%) in the wavelength range of the plasmonic response in comparison to the randomly arranged ones. Compared to uniform nano-porous layers, a much larger sheet resistance (up to 12 times) for random nano-porous layers is observed. The uniform and random Ag nano-porous layers possessing the strong plasmonic response over whole visible range can reach an average transmittance of 90 and 80% at the sheet resistance of 10 and 20 Ohm/sq, respectively, which is comparable to widely used ITO electrodes.

  11. Heat transport in polymer thin films for micro/nano-manufacturing

    Science.gov (United States)

    Hung, Ming-Tsung

    The rapid growth in micro/nanotechnology has opened a great opportunity for polymer thin films and polymer nanocomposites. Thermal management or thermal effects in those applications need to be carefully examined. For example, the local heating in electron-beam lithography, emersion lithography, and scanning near field optical lithography may cause the degradation of photoresists and reduce the resolution. The development of many organic electronics, polymer micro-electro-mechanical-systems (MEMS) devices, and polymer nanocomposites may require the knowledge of heat transport in micro/nano-sized polymers. Thermolithography, a novel lithography, uses controlled localized heating to transfer patterns and requires the thermal conductivity data to control. It is of considerable scientific and technological interests for study heat transport in polymer thin films. Unlike bulk polymers that can be measured using commercially available instruments, polymer thin films are difficult to measure. In this manuscript, we develop the measurement techniques suitable for measuring thermal conductivity of polymer thin films and polymer nanocomposites. Using a microfabricated membrane-based device, we study the heat conduction in photoresists at difference process stages. This data is used in our thermolithography study, where we use microheater to study the kinetic of crosslinking reaction of photoresist. The feasibility of thermolithography and potential three dimensional micro/nano-fabrication is presented. The uniqueness of thermolithography is also demonstrated by patterning amorphous fluoropolymers. A modified hot-wire technique is used to measure the thermal conductivity of graphite nanoplatelet (GNP) reinforced nanocomposites, one of the promising candidates for multifunctional materials. Thermal interface resistance in GNP nanocomposites is investigated, which shows a strong effect on energy transport in the nanocomposites and can be diminished through surface treatment.

  12. Preparation of nano-Ag/TiO2 thin-film

    Institute of Scientific and Technical Information of China (English)

    PENG Bing; WANG Jia; CHAI Li-yuan; MAO Ai-li; WANG Yun-yan

    2008-01-01

    Steady TiO2 water-sol was prepared by peptization and the effects of pH value, temperature, concentration of colloid and peptizator on sol were investigated. Laser grain analyzer was used to verify nano-particles in the sol. The photocatalytic degradation ratio and antibacterial property of nano-Ag/TiO2 thin-film on ceramics were used as the main index in addition to XRD analysis. The effect of film layers, embedding Ag+, annealing temperature and time on the degradation ratio and antibacterial property was studied. The temperature 30-80 ℃, pH 1.2-2.0, concentrations of 0.05-0.3 mol/L sol and 5% HNO3 would be the optimal parameters for the TiO2 water-sol preparation. The nano-Ag/TiO2 film of three layers with 3% AgNO3 embedded and treated at 350 ℃ for 2 h exhibits good performance. The elementary research on the kinetics of degradation shows that the reactions are on the first order kinetics equation.

  13. Ground state study of the thin ferromagnetic nano-islands for artificial spin ice arrays

    Energy Technology Data Exchange (ETDEWEB)

    Vieira Júnior, D. S., E-mail: damiao.vieira@ifsudestemg.edu.br [Departamento Acadêmico de Matemática, Física e Estatística, Instituto Federal de Educação, Ciência e Tecnologia do Sudeste de Minas Gerais - Câmpus Rio Pomba, Rio Pomba, Minas Gerais 36180-000 (Brazil); Departamento de Física, Laboratório de Simulação Computacional, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais 36036-330 (Brazil); Leonel, S. A., E-mail: sidiney@fisica.ufjf.br; Dias, R. A., E-mail: radias@fisica.ufjf.br; Toscano, D., E-mail: danilotoscano@fisica.ufjf.br; Coura, P. Z., E-mail: pablo@fisica.ufjf.br; Sato, F., E-mail: sjfsato@fisica.ufjf.br [Departamento de Física, Laboratório de Simulação Computacional, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais 36036-330 (Brazil)

    2014-09-07

    In this work, we used numerical simulations to study the magnetic ground state of the thin elongated (elliptical) ferromagnetic nano-islands made of Permalloy. In these systems, the effects of demagnetization of dipolar source generate a strong magnetic anisotropy due to particle shape, defining two fundamental magnetic ground state configurations—vortex or type C. To describe the system, we considered a model Hamiltonian in which the magnetic moments interact through exchange and dipolar potentials. We studied the competition between the vortex states and aligned states—type C—as a function of the shape of each elliptical nano-islands and constructed a phase diagram vortex—type C state. Our results show that it is possible to obtain the elongated nano-islands in the C-state with aspect ratios less than 2, which is interesting from the technological point of view because it will be possible to use smaller islands in spin ice arrays. Generally, the experimental spin ice arrangements are made with quite elongated particles with aspect ratio approximately 3 to ensure the C-state.

  14. A reversible bipolar WORM device based on AlOxNy thin film with Al nano phase embedded

    Science.gov (United States)

    Zhu, W.; Li, J.; Zhang, L.; Hu, X. C.

    2017-03-01

    An Al-rich AlOxNy thin film based reversible Write-Once-Read-Many-Times (WORM) memory device with MIS structure could transit from high resistance state (HRS, ∼1011 Ω) to low resistance state (LRS, ∼105 Ω) by sweeping voltage up to ∼20 V. The first switching could be recorded as writing process for WORM device which may relate to conductive path are formed through the thin film. The conductive path should be formed by both Al nano phase and oxygen vacancies. Among of them, Al nano phases are not easy to move, but oxygen vacancies could migrate under high E-field or at high temperature environment. Such conductive path is not sensitive to charging effect after it formed, but it could be broken by heating effect, which may relate to the migration of excess Al ions and oxygen vacancies at high temperature. After baking LRS (ON state) WORM device at 200 °C for 2 min, the conductivity will decrease to HRS which indicates conductive path is broken and device back to HRS (OFF state) again. This phenomenon could be recorded as recovery process. Both writing and recovery process related to migration of oxygen vacancies and could be repeated over 10 times in this study. It also indicates that there is no permanent breakdown occurred in MIS structured WORM device operation. We suggest that this conductive path only can be dissolved by a temperature sensitive electro-chemical action. This WORM device could maintain at LRS over 105 s with on-off ratio over 4 orders.

  15. Micro- and nano-tubules built from loosely and tightly rolled up thin sheets.

    Science.gov (United States)

    Losensky, Luisa; Goldenbogen, Björn; Holland, Gudrun; Laue, Michael; Petran, Anca; Liebscher, Jürgen; Scheidt, Holger A; Vogel, Alexander; Huster, Daniel; Klipp, Edda; Arbuzova, Anna

    2016-01-14

    Tubular structures built from amphiphilic molecules are of interest for nano-sensing, drug delivery, and structuring of oils. In this study, we characterized the tubules built in aqueous suspensions of a cholesteryl nucleoside conjugate, cholesterylaminouridine (CholAU) and phosphatidylcholines (PCs). In mixtures with unsaturated PCs having chain lengths comparable to the length of CholAU, two different types of tubular structures were observed; nano- and micro-tubules had average diameters in the ranges 50-300 nm and 2-3 μm, respectively. Using cryo scanning electron microscopy (cryo-SEM) we found that nano- and micro-tubules differed in their morphology: the nano-tubules were densely packed, whereas micro-tubules consisted of loosely rolled undulated lamellas. Atomic force microscopy (AFM) revealed that the nano-tubules were built from 4 to 5 nm thick CholAU-rich bilayers, which were in the crystalline state. Solid-state (2)H NMR spectroscopy also confirmed that about 25% of the total CholAU, being about the fraction of CholAU composing the tubules, formed the rigid crystalline phase. We found that CholAU/PC tubules can be functionalized by molecules inserted into lipid bilayers and fluorescently labeled PCs and lipophilic nucleic acids inserted spontaneously into the outer layer of the tubules. The tubular structures could be loaded and cross-linked, e.g. by DNA hybrids, and, therefore, are of interest for further development, e.g. as a depot scaffold for tissue regeneration.

  16. Carbon nanotube thin film strain sensor models assembled using nano- and micro-scale imaging

    Science.gov (United States)

    Lee, Bo Mi; Loh, Kenneth J.; Yang, Yuan-Sen

    2017-02-01

    Nanomaterial-based thin films, particularly those based on carbon nanotubes (CNT), have brought forth tremendous opportunities for designing next-generation strain sensors. However, their strain sensing properties can vary depending on fabrication method, post-processing treatment, and types of CNTs and polymers employed. The objective of this study was to derive a CNT-based thin film strain sensor model using inputs from nano-/micro-scale experimental measurements of nanotube physical properties. This study began with fabricating ultra-low-concentration CNT-polymer thin films, followed by imaging them using atomic force microscopy. Image processing was employed for characterizing CNT dispersed shapes, lengths, and other physical attributes, and results were used for building five different types of thin film percolation-based models. Numerical simulations were conducted to assess how the morphology of dispersed CNTs in its 2D matrix affected bulk film electrical and electromechanical (strain sensing) properties. The simulation results showed that CNT morphology had a significant impact on strain sensing performance.

  17. Carbon nanotube thin film strain sensor models assembled using nano- and micro-scale imaging

    Science.gov (United States)

    Lee, Bo Mi; Loh, Kenneth J.; Yang, Yuan-Sen

    2017-07-01

    Nanomaterial-based thin films, particularly those based on carbon nanotubes (CNT), have brought forth tremendous opportunities for designing next-generation strain sensors. However, their strain sensing properties can vary depending on fabrication method, post-processing treatment, and types of CNTs and polymers employed. The objective of this study was to derive a CNT-based thin film strain sensor model using inputs from nano-/micro-scale experimental measurements of nanotube physical properties. This study began with fabricating ultra-low-concentration CNT-polymer thin films, followed by imaging them using atomic force microscopy. Image processing was employed for characterizing CNT dispersed shapes, lengths, and other physical attributes, and results were used for building five different types of thin film percolation-based models. Numerical simulations were conducted to assess how the morphology of dispersed CNTs in its 2D matrix affected bulk film electrical and electromechanical (strain sensing) properties. The simulation results showed that CNT morphology had a significant impact on strain sensing performance.

  18. Polychromatic white LED using GaN nano pyramid structure

    Science.gov (United States)

    Kim, Taek; Kim, Jusung; Yang, Moonseung; Park, Yongsoo; Chung, U.-In; Ko, Yongho; Cho, Yonghoon

    2013-03-01

    We have developed monolithic white light emitting diodes (LEDs) with a hybrid structure of planar c-planes and nano size hexagonal pyramids. The white spectrum is composed of blue and yellow emissions from the InGaN multi quantum wells (MQWs) on the planar c-planes and on the nano pyramids, respectively. The yellow emission is originated from quantum wells, wires, and dots that are formed at the sides, edges, and tops of the nano-pyramids, respectively. As a result, the emission peaks are different and the entire yellow spectrum is broad enough to make a white in combination with a blue emission. The longer wavelength from the InGaN on nano-pyramids than the wavelength from the InGaN on c-planes is explained by excess In supply from the dielectric selective growth mask. The color temperature is tuned from 3600K to 6400K by controlling the relative area ratio of c-plane and nano-pyramids.

  19. Nano-sized Adsorbate Structure Formation in Anisotropic Multilayer System

    Science.gov (United States)

    Kharchenko, Vasyl O.; Kharchenko, Dmitrii O.; Yanovsky, Vladimir V.

    2017-05-01

    In this article, we study dynamics of adsorbate island formation in a model plasma-condensate system numerically. We derive the generalized reaction-diffusion model for adsorptive multilayer system by taking into account anisotropy in transfer of adatoms between neighbor layers induced by electric field. It will be found that with an increase in the electric field strength, a structural transformation from nano-holes inside adsorbate matrix toward separated nano-sized adsorbate islands on a substrate is realized. Dynamics of adsorbate island sizes and corresponding distributions are analyzed in detail. This study provides an insight into details of self-organization of adatoms into nano-sized adsorbate islands in anisotropic multilayer plasma-condensate systems.

  20. Microstructure characterization and magnetic properties of nano structured materials

    Energy Technology Data Exchange (ETDEWEB)

    Sun, X.C

    2000-07-01

    The present thesis deals with the unique microstructural properties and their novel magnetic properties of core-shell Ni-Ce nano composite particles, carbon encapsulated Fe, Co, and Ni nanoparticles and the nano crystallization behavior of typical ferromagnetic Fe{sub 78}Si{sub 9}B{sub 13} ribbons. These properties have intensively been investigated by high resolution transmission electron microscopy (HREM), X-ray diffraction (XRD), scanning electron microscopy (Sem), X-ray energy dispersive spectroscopy [eds.]; selected area electron diffraction pattern (SAED), Ft-IR, differential scanning calorimeter (DSC). In addition, magnetic moments measurements at different temperatures and applied fields have been performed by transmission Moessbauer spectroscopy, superconducting quantum interference device magnetometer (SQUID), and vibrating sample magnetometer (VSM). The present studies may provide the insights for the better understanding of the correlation between the unique microstructure and novel magnetic properties for several magnetic nano structured materials. (Author)

  1. An optimized surface plasmon photovoltaic structure using energy transfer between discrete nano-particles.

    Science.gov (United States)

    Lin, Albert; Fu, Sze-Ming; Chung, Yen-Kai; Lai, Shih-Yun; Tseng, Chi-Wei

    2013-01-14

    Surface plasmon enhancement has been proposed as a way to achieve higher absorption for thin-film photovoltaics, where surface plasmon polariton(SPP) and localized surface plasmon (LSP) are shown to provide dense near field and far field light scattering. Here it is shown that controlled far-field light scattering can be achieved using successive coupling between surface plasmonic (SP) nano-particles. Through genetic algorithm (GA) optimization, energy transfer between discrete nano-particles (ETDNP) is identified, which enhances solar cell efficiency. The optimized energy transfer structure acts like lumped-element transmission line and can properly alter the direction of photon flow. Increased in-plane component of wavevector is thus achieved and photon path length is extended. In addition, Wood-Rayleigh anomaly, at which transmission minimum occurs, is avoided through GA optimization. Optimized energy transfer structure provides 46.95% improvement over baseline planar cell. It achieves larger angular scattering capability compared to conventional surface plasmon polariton back reflector structure and index-guided structure due to SP energy transfer through mode coupling. Via SP mediated energy transfer, an alternative way to control the light flow inside thin-film is proposed, which can be more efficient than conventional index-guided mode using total internal reflection (TIR).

  2. Synthesis of α-MoO3 nano-flakes by dry oxidation of RF sputtered Mo thin films and their application in gas sensing

    Science.gov (United States)

    Dwivedi, Priyanka; Dhanekar, Saakshi; Das, Samaresh

    2016-11-01

    Synthesis of orthorhombic (α) MoO3 nano-flakes by dry oxidation of RF sputtered Mo thin film is presented. The influence of Mo thickness variation, oxidation temperature and time on the crystallographic structure, surface morphology and roughness of MoO3 thin films was studied using SEM, AFM, XRD and Raman spectroscopy. A structural study shows that MoO3 is polycrystalline in nature with an α phase. It was noticed that oxidation temperature plays an important role in the formation of nano-flakes. The synthesis technique proposed is simple and suitable for large scale productions. The synthesis parameters were optimized for the fabrication of sensors. Chrome gold-based IDE (interdigitated electrodes) structures were patterned for the electrical detection of organic vapors. Sensors were exposed to wide range 5-100 ppm of organic vapors like ethanol, acetone, IPA (isopropanol alcohol) and water vapors. α-MoO3 nano-flakes have demonstrated selective sensing to acetone in the range of 10-100 ppm at 150 °C. The morphology of such nanostructures has potential in applications such as sensor devices due to their high surface area and thermal stability.

  3. Study of nano imprinting using soft lithography on Krafty glue and PVDF polymer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sankar, M. S. Ravi, E-mail: rameshg.phy@pondiuni.edu; Gangineni, Ramesh Babu, E-mail: rameshg.phy@pondiuni.edu [Department of Physics, Pondicherry University, R. V. Nagar, Kalapet, Puducherry - 605014 (India)

    2014-04-24

    The present work reveals soft lithography strategy based on self assembly and replica molding for carrying out micro and nanofabrication. It provides a convenient, effective and very low cost method for the formation and manufacturing of micro and nano structures. Al-layer of compact disc (sony CD-R) used as a stamp with patterned relief structures to generate patterns and structures with pattern size of 100nm height, 1.7 μm wide. In literature, PDMS (Polydimethylsiloxane) solution is widely used to get negative copy of the Al-layer. In this work, we have used inexpensive white glue (Polyvinylacetate + water), 15gm (□5) and PVDF (Polyvinylidene difluoride) spin coated films and successfully transferred the nano patterns of Al layer on to white glue and PVDF films.

  4. Charge transport through exciton shelves in cadmium chalcogenide quantum dot-DNA nano-bioelectronic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, Samuel M.; Singh, Vivek [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Noh, Hyunwoo [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Materials Science and Engineering Program and Department of Nanoengineering, University of California, 9500 Gilman Drive, La Jolla, San Diego, California 92093 (United States); Cha, Jennifer N. [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Materials Science and Engineering Program and Department of Nanoengineering, University of California, 9500 Gilman Drive, La Jolla, San Diego, California 92093 (United States); Materials Science and Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Nagpal, Prashant, E-mail: pnagpal@colorado.edu [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Materials Science and Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Renewable and Sustainable Energy Institute, University of Colorado Boulder, 2445 Kittredge Loop, Boulder, Colorado 80309 (United States)

    2015-02-23

    Quantum dot (QD), or semiconductor nanocrystal, thin films are being explored for making solution-processable devices due to their size- and shape-tunable bandgap and discrete higher energy electronic states. While DNA has been extensively used for the self-assembly of nanocrystals, it has not been investigated for the simultaneous conduction of multiple energy charges or excitons via exciton shelves (ES) formed in QD-DNA nano-bioelectronic thin films. Here, we present studies on charge conduction through exciton shelves, which are formed via chemically coupled QDs and DNA, between electronic states of the QDs and the HOMO-LUMO levels in the complementary DNA nucleobases. While several challenges need to be addressed in optimizing the formation of devices using QD-DNA thin films, a higher charge collection efficiency for hot-carriers and our detailed investigations of charge transport mechanism in these thin films highlight their potential for applications in nano-bioelectronic devices and biological transducers.

  5. Imprinted and injection-molded nano-structured optical surfaces

    DEFF Research Database (Denmark)

    Christiansen, Alexander Bruun; Højlund-Nielsen, Emil; Clausen, Jeppe Sandvik

    2013-01-01

    Inspired by nature, nano-textured surfaces have attracted much attention as a method to realize optical surface functionality. The moth-eye antireflective structure and the structural colors of Morpho butterflies are wellknown examples used for inspiration for such biomimetic research...... of light from polymer surfaces and their implication for creating structural colors is discussed. In the case of injection-moulding compatible designs, the maximum reflection of nano-scale textured surfaces cannot exceed the Fresnel reflection of a corresponding flat polymer surface, which is approx. 4...... % for normal incidence. Diffraction gratings provide strong color reflection defined by the diffraction orders. However, the apperance varies strongly with viewing angles. Three different methods to address the strong angular-dependence of diffraction grating based structural color are discussed....

  6. Structure and morphology of laser-ablated WO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, O.M.; Swapnasmitha, A.S. [Sri Venkateswara University, Department of Physics, Tirupati (India); John, J.; Pinto, R. [Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai (India)

    2005-11-01

    The structure and surface morphology of WO{sub 3} thin films deposited by a laser-ablation technique have been found to be strongly dependent on the deposition conditions and the nature of the substrate. By precisely controlling the substrate temperature and the oxygen partial pressure, amorphous, polycrystalline, nano-crystalline and iso-epitaxial WO{sub 3} thin films were successfully grown. The structure and surface morphological features of the films from X-ray diffraction and atomic force microscopy data are described in relation to the deposition conditions. (orig.)

  7. Effects of neutral particle beam on nano-crystalline silicon thin films, with application to thin film transistor backplane for flexible active matrix organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jin Nyoung; Song, Byoung Chul; Lee, Dong Hyeok [Dept. of Display and Semiconductor Physics, Korea University, Chungnam (Korea, Republic of); Yoo, Suk Jae; Lee, Bonju [National Fusion Research Institute, 52, Yuseong-Gu, Deajeon, 305-333 (Korea, Republic of); Hong, MunPyo, E-mail: goodmoon@korea.ac.kr [Dept. of Display and Semiconductor Physics, Korea University, Chungnam (Korea, Republic of)

    2011-08-01

    A novel deposition process for nano-crystalline silicon (nc-Si) thin films was developed using neutral beam assisted chemical vapor deposition (NBaCVD) technology for the application of the thin film transistor (TFT) backplane of flexible active matrix organic light emitting diode (AMOLED). During the formation of a nc-Si thin film, the energetic particles enhance nano-sized crystalline rather microcrystalline Si in thin films. Neutral Particle Beam (NPB) affects the crystallinity in two ways: (1) NPB energy enhances nano-crystallinity through kinetic energy transfer and chemical annealing, and (2) heavier NPB (such as Ar) induces damage and amorphization through energetic particle impinging. Nc-Si thin film properties effectively can be changed by the reflector bias. As increase of NPB energy limits growing the crystalline, the performance of TFT supports this NPB behavior. The results of nc-Si TFT by NBaCVD demonstrate the technical potentials of neutral beam based processes for achieving high stability and reduced leakage in TFT backplanes for AMOLEDs.

  8. Direct solvent induced microphase separation, ordering and nano-particles infusion of block copolymer thin films

    Science.gov (United States)

    Modi, Arvind; Sharma, Ashutosh; Karim, Alamgir

    2013-03-01

    Kinetics of block copolymer (BCP) microphase separation by thermal annealing is often a challenge to low-cost and faster fabrication of devices because of the slow ordering. Towards the objective of rapid processing and accessing desired nanostructures, we are developing methods that enable a high degree of mobility of BCP phases while maintaining phase separation conditions via control of effective interaction parameter between the blocks in BCP thin films. We study the self-assembly of PS-P2VP thin films in various solvent mixtures. While non-solvent prevents dissolution of film into the bulk solution, the good solvent penetrates the film and makes polymer chains mobile. As a result of controlled swelling and mobility of BCP blocks, solvent annealing of pre-cast BCP thin films in liquid mixture of good solvent and non-solvent is a promising method for rapid patterning of nanostructures. Interestingly, we demonstrate simultaneous BCP microphase separation and infusion of gold nano-particles into selective phase offering a wide range of application from plasmonics to nanoelectronics. University of Akron Research Foundation (UARF)

  9. Characterization and modelling of the elastic properties of nano-structured W/Cu multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Castelnau, O. [LPMTM-CNRS, av. J.B. Clement, Universite Paris-Nord, 93430 Villetaneuse (France)], E-mail: olivier.castelnau@lpmtm.univ-paris13.fr; Geandier, G.; Renault, P.-O.; Goudeau, Ph.; Le Bourhis, E. [LMP, UMR 6630 CNRS, Universite de Poitiers, B. P. 30179, 86962 Futuroscope (France)

    2007-12-03

    Understanding the mechanical behavior of nano-structured thin films in relation to their microstructure, in particular to the grain size, is of utmost importance for the development of technological applications. Model nanometric W/Cu multilayers exhibiting different microstructures and supported by a (thin) polyimide substrate are elaborated. The films mechanical response is characterized experimentally by tensile tests carried out in-situ in an X-ray diffractometer installed at a synchrotron beam line. The orientation dependence of elastic strains and stresses is determined by an appropriate micromechanical model accounting for the material microstructure, and based on homogenization schemes. While a good agreement is globally found, the model better reproduces the experimental results of the W component than those of Cu, due probably to the elastic anisotropy of Cu grains.

  10. Nonlinear optical properties of polyaniline and poly (o-toluidine) composite thin films with multi walled carbon nano tubes

    Science.gov (United States)

    Nagaraja, K. K.; Pramodini, S.; Poornesh, P.; Telenkov, M. P.; Kityk, I. V.

    2017-05-01

    We report the improved third-order nonlinear optical properties of polyaniline and poly (o-toluidine) with different doping concentrations of multi walled carbon nano tube (MWCNTs) composite thin films investigated using z-scan technique and continuous wave He-Ne laser at 633 nm wavelength was used as source of excitation. Thin films were prepared by spin coating technique on glass substrate. The structural properties of the composite films were analysed by X-ray diffraction studies and the characteristic peaks corresponding to MWCNTs and polymers have been observed. The surface morphology of the deposited films was analysed using scanning electron microscopy and it confirms that the polymer in the composites has been coated on the MWCNTs homogeneously. The z-scan results reveal that the films exhibit reverse saturable absorption and self-defocusing nonlinearity. The third-order nonlinear optical susceptibility χ(3) is found to be of the order of 10-3 esu. Also, optical power limiting and clamping experiment was performed. The clamping values increases with increase in concentration and the lowest clamping observed for composite films are 1 mW and 0.7 mW.

  11. Nonlinear optical properties of polyaniline and poly (o-toluidine) composite thin films with multi walled carbon nano tubes

    Energy Technology Data Exchange (ETDEWEB)

    Nagaraja, K.K. [National University of Science and Technology “MISiS”, Leninskii pr. 4, Moscow 119049 (Russian Federation); Pramodini, S. [Department of Physics, School of Engineering and Technology, Jain University, Jakkasandra Post, Bengaluru 5621112, Karnataka (India); Poornesh, P., E-mail: poorneshp@gmail.com [Nonlinear Optics Research Laboratory, Department of Physics, Manipal Institute of Technology, Manipal University, Manipal 576 104, Karnataka (India); Telenkov, M.P. [National University of Science and Technology “MISiS”, Leninskii pr. 4, Moscow 119049 (Russian Federation); Kityk, I.V. [Electrical Engineering Department, Czestochowa University Technology, Czestochowa (Poland)

    2017-05-01

    We report the improved third-order nonlinear optical properties of polyaniline and poly (o-toluidine) with different doping concentrations of multi walled carbon nano tube (MWCNTs) composite thin films investigated using z-scan technique and continuous wave He–Ne laser at 633 nm wavelength was used as source of excitation. Thin films were prepared by spin coating technique on glass substrate. The structural properties of the composite films were analysed by X-ray diffraction studies and the characteristic peaks corresponding to MWCNTs and polymers have been observed. The surface morphology of the deposited films was analysed using scanning electron microscopy and it confirms that the polymer in the composites has been coated on the MWCNTs homogeneously. The z-scan results reveal that the films exhibit reverse saturable absorption and self-defocusing nonlinearity. The third-order nonlinear optical susceptibility χ{sup (3)} is found to be of the order of 10{sup −3} esu. Also, optical power limiting and clamping experiment was performed. The clamping values increases with increase in concentration and the lowest clamping observed for composite films are 1 mW and 0.7 mW.

  12. Fabrication of semi-transparent superoleophobic thin film from fabrics and nanoparticle-based hierarchical structure

    Directory of Open Access Journals (Sweden)

    Nishizawa S.

    2013-08-01

    Full Text Available Superoleophobic thin films have many potential applications including fluid transfer, fluid power systems, stain resistant and antifouling materials, and microfluidics among others. Transparency is also desired with superhydrophobicity for their numerous applications; however transparency and oleophobicity are almost incompatible relationship with each other in the point of surface structure. Because oleophobicity required rougher structure at nano-micro scale than hydrophobicity, and these rough structure brings light scattering. So far, there is very few report of the compatible of transparency and superoleophobicity. In this report, we proposed the see-through type fabrics using the nanoparticle-based hierarchical structure thin film for improving both of oleophobicity and transparency. The vacant space between fibrils of fabrics has two important roles: the one is to through the light, another one is to introduce air layer to realize Cassie state of liquid droplet on thin film. To realize the low surface energy and nanoscale rough structure surface on fibrils, we used the spray method with perfluoroalkyl methacrylic copolymer (PMC, silica nano particles and volatile solvent. From the SEM image, the hierarchical structures of nanoparticle were formed uniformly on the fabrics. The transparency of thin film obtained was approximately 61% and the change of transparency between pre-coated fabrics and coated was 11%. From investigation of the surface wettability, the contact angles of oils (rapeseed oil and hexadecane and water droplet on the fabricated film were over 150 degree.

  13. Thermal treatment of solution-processed nano-sized thin films of molybdenum oxide

    Science.gov (United States)

    Ganchev, M.; Sendova-Vassileva, M.; Popkirov, G.; Vitanov, P.

    2016-10-01

    A solution based deposition method to form nano-sized thin films of molybdenum oxide suitable for photovoltaic device applications is presented. The samples were deposited by spin-coating from molybdenum metal organic precursor solution on soda lime glass substrates. The influence of the process parameters such as spinning regime and concentration of the precursor solutions on the thickness and morphology of the films were investigated. The thermal decomposition of the molybdenum precursor and oxide formation were investigated by differential scanning calorimetry and characteristic patterns showed transitions up to 300oC followed by a zone of stability. Optical spectroscopy measurements in the wavelength range from 300 to 1800 nm presented an increase in transparency when temperature of annealing was raised up to 400oC. Raman scattering analysis revealed the presence of mixed molybdenum oxides. Measurements of the electrical conductivity were performed by the 4-point method.

  14. Transparent conducting electrodes based on thin, ultra-long copper nanowires and graphene nano-composites

    Science.gov (United States)

    Zhu, Zhaozhao; Mankowski, Trent S.; Balakrishnan, Kaushik; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine A.; Mansuripur, Masud; Falco, Charles M.

    2014-10-01

    High aspect-ratio ultra-long (> 70 μm) and thin (< 50 nm) copper nanowires (Cu-NW) were synthesized in large quantities using a solution-based approach. The nanowires, along with reduced graphene-oxide sheets, were coated onto glass as well as plastic substrates, thus producing transparent conducting electrodes. Our fabricated transparent electrodes achieved high optical transmittance and low sheet resistance, comparable to those of existing Indium Tin Oxide (ITO) electrodes. Furthermore, our electrodes show no notable loss of performance under high temperature and high humidity conditions. Adaptations of such nano-materials into smooth and ultrathin films lead to potential alternatives for the conventional tin-doped indium oxide, with applications in a wide range of solar cells, flexible displays, and other opto-electronic devices.

  15. Remarkable enantioselectivity of molecularly imprinted TiO{sub 2} nano-thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mizutani, Naoki; Yang, Do-Hyeon; Selyanchyn, Roman; Korposh, Sergiy [Graduate School of Environmental Engineering, University of Kitakyushu, 1-1 Hibikino, Kitakyushu 808-0135 (Japan); Lee, Seung-Woo, E-mail: leesw@env.kitakyu-u.ac.jp [Graduate School of Environmental Engineering, University of Kitakyushu, 1-1 Hibikino, Kitakyushu 808-0135 (Japan); Kunitake, Toyoki [Graduate School of Environmental Engineering, University of Kitakyushu, 1-1 Hibikino, Kitakyushu 808-0135 (Japan)

    2011-05-23

    TiO{sub 2} nano-thin films with imprinted (R)- and (S)-enantiomers of propranolol, 1,1'-bi-naphthol, and 2-(4-isobutylphenyl)-propionic acid were fabricated on quartz plates by spin-coating their solutions with Ti(O-{sup n}Bu){sub 4} in a toluene-ethanol mixture (1:1, v/v). After template removal, the imprinted films showed better binding for original templates than to the corresponding enantiomers. The assessment of template incorporation, template removal, and re-binding was conducted through UV-vis measurements. Significant enhancement of enantioselectivity was achieved by optimization of the film thickness and by heat-treatment of the imprinted films. After subtraction of non-specific binding, the optimized films provided chiral recognition with the enantioselectivity of almost 100% for (R)-propranolol and 95% for (S)-propranolol.

  16. Evaporation characteristics of thin film liquid argon in nano-scale confinement: A molecular dynamics study

    Science.gov (United States)

    Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

    2016-07-01

    Molecular dynamics simulation has been carried out to explore the evaporation characteristics of thin liquid argon film in nano-scale confinement. The present study has been conducted to realize the nano-scale physics of simultaneous evaporation and condensation inside a confined space for a three phase system with particular emphasis on the effect of surface wetting conditions. The simulation domain consisted of two parallel platinum plates; one at the top and another at the bottom. The fluid comprised of liquid argon film at the bottom plate and vapor argon in between liquid argon and upper plate of the domain. Considering hydrophilic and hydrophobic nature of top and bottom surfaces, two different cases have been investigated: (i) Case A: Both top and bottom surfaces are hydrophilic, (ii) Case B: both top and bottom surfaces are hydrophobic. For all cases, equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. Then the lower wall was set to four different temperatures such as 110 K, 120 K, 130 K and 140 K to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat fluxes normal to top and bottom walls were estimated and discussed to illuminate the effectiveness of heat transfer in both hydrophilic and hydrophobic confinement at various boundary temperatures of the bottom plate.

  17. Controlled release of an anti-cancer drug from DNA structured nano-films

    Science.gov (United States)

    Cho, Younghyun; Lee, Jong Bum; Hong, Jinkee

    2014-02-01

    We demonstrate the generation of systemically releasable anti-cancer drugs from multilayer nanofilms. Nanofilms designed to drug release profiles in programmable fashion are promising new and alternative way for drug delivery. For the nanofilm structure, we synthesized various unique 3-dimensional anti cancer drug incorporated DNA origami structures (hairpin, Y, and X shaped) and assembled with peptide via layer-by-layer (LbL) deposition method. The key to the successful application of these nanofilms requires a novel approach of the influence of DNA architecture for the drug release from functional nano-sized surface. Herein, we have taken first steps in building and controlling the drug incorporated DNA origami based multilayered nanostructure. Our finding highlights the novel and unique drug release character of LbL systems in serum condition taken full advantages of DNA origami structure. This multilayer thin film dramatically affects not only the release profiles but also the structure stability in protein rich serum condition.

  18. Nano-Engineered Structural Joints Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A versatile class of high-performance structural joints is proposed where massive interatomic bonds over the large surface areas of nanostructured surfaces...

  19. Nonequilibrium band structure of nano-devices

    Science.gov (United States)

    Hackenbuchner, S.; Sabathil, M.; Majewski, J. A.; Zandler, G.; Vogl, P.; Beham, E.; Zrenner, A.; Lugli, P.

    2002-03-01

    A method is developed for calculating, in a consistent manner, the realistic electronic structure of three-dimensional (3-D) heterostructure quantum devices under bias and its current density close to equilibrium. The nonequilibrium electronic structure is characterized by local Fermi levels that are calculated self-consistently. We have applied this scheme to predict asymmetric Stark shifts and tunneling of confined electrons and holes in single-dot GaAs/InGaAs photodiodes.

  20. Structured electron beams from nano-engineered cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Lueangaramwong, A. [NICADD, DeKalb; Mihalcea, D. [NICADD, DeKalb; Andonian, G. [RadiaBeam Tech.; Piot, P. [Fermilab

    2017-03-07

    The ability to engineer cathodes at the nano-scale have open new possibilities such as enhancing quantum eciency via surface-plasmon excitation, forming ultra-low-emittance beams, or producing structured electron beams. In this paper we present numerical investigations of the beam dynamics associated to this class of cathode in the weak- and strong-field regimes.We finally discuss the possible applications of some of the achievable cathode patterns when coupled with other phase space manipulations.

  1. Nano-structured polymer composites and process for preparing same

    Science.gov (United States)

    Hillmyer, Marc; Chen, Liang

    2013-04-16

    A process for preparing a polymer composite that includes reacting (a) a multi-functional monomer and (b) a block copolymer comprising (i) a first block and (ii) a second block that includes a functional group capable of reacting with the multi-functional monomer, to form a crosslinked, nano-structured, bi-continuous composite. The composite includes a continuous matrix phase and a second continuous phase comprising the first block of the block copolymer.

  2. STRUCTURE AND DYNAMICS OF POLYMERIC MATERIALS IN NANO-SCALE

    Institute of Scientific and Technical Information of China (English)

    Toshio Nishi; So Fujinami; Dong Wang; Hao Liu; Ken Nakajima

    2011-01-01

    The nano-palpation technique, i.e., nanometer-scale elastic and viscoelastic measurements based on atomic force microscope, is introduced. It is demonstrated to be very useful in analyzing nanometer-scale materials properties for the surfaces and interfaces of various types of soft materials. It enables us to obtain not only structural information but also mechanical information about a material at the same place and at the same time.

  3. Structured electron beams from nano-engineered cathodes

    Science.gov (United States)

    Lueangaramwong, A.; Mihalcea, D.; Andonian, G.; Piot, P.

    2017-03-01

    The ability to engineer cathodes at the nano-scale have opened new possibilities such as enhancing quantum efficiency via surface-plasmon excitation, forming ultra-low-emittance beams, or producing structured electron beams. In this paper, we present numerical investigations of the beam dynamics associated with this class of cathode in the weak- and strong-field regimes. We finally discuss the possible applications of some of the achievable cathode patterns when coupled with other phase space manipulations.

  4. Nano-structured alloy and composite coatings for high temperature applications

    Directory of Open Access Journals (Sweden)

    Wei Gao

    2004-03-01

    Full Text Available Nano-structured materials often possess special properties that materials with identical compositions but ordinary grain size do not have. This paper reports our work on the surface nano-crystallisation and nano-structured alloy and composite coatings. A number of processing methods including magnetron sputtering, thermal spray and pulse electro-spark deposition have been used to produce surface nano-crystalline structure. The compositions and microstructures can be well controlled by using different targets or electrodes, nano-structured composites and adjusting processing parameters. Surface nano-structured coatings can provide special chemical, mechanical and electronic properties such as high temperature corrosion and corrosive wear resistance. It has potential applications such as turbine blades, engine parts for petrochemical, aerospace and electronic device industries. This paper is focused on the study of the interrelations between processing, microstructure and properties. Physical models have been established to explain the effects of nano-crystalline structure on the properties.

  5. Osteoblast Behavior on Hierarchical Micro-/Nano-Structured Titanium Surface

    Institute of Scientific and Technical Information of China (English)

    Weiyan Meng; Yanmin Zhou; Yanjing Zhang; Qing Cai; Liming Yang; Jinghui Zhao; Chnnyan Li

    2011-01-01

    In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hierarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching (EE). MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched (SLA) as well as Machined (M) surfaces respectively. The results show significant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.

  6. Manufacture of Nano Structures in Polymer Material

    DEFF Research Database (Denmark)

    Hansen, Hans Nørgaard; Pedersen, H.C.; Staun, Jacob

    2003-01-01

    components are to be used in a microsystem, subsequent handling and assembly is necessary. The present paper describes the process chain related to the manufacture of optical gratings with nanometer-sized structures. The problems of each process step and the challenges of establishing a coherent production...

  7. Structural evolution of Ag-Cu nano-alloys confined between AlN nano-layers upon fast heating.

    Science.gov (United States)

    Janczak-Rusch, J; Chiodi, M; Cancellieri, C; Moszner, F; Hauert, R; Pigozzi, G; Jeurgens, L P H

    2015-11-14

    The structural evolution of a Ag-Cu/AlN nano-multilayer (NML), as prepared by magnetron-sputtering on a α-Al2O3 substrate, was monitored during fast heating by real-time in situ XRD analysis (at the synchrotron), as well as by ex situ microstructural analysis using SEM, XPS and in-house XRD. The as-deposited NML is constituted of alternating nano-layers (thickness ≈ 10 nm) of a chemically inert AlN barrier and a eutectic Ag-Cu(40at%) nano-alloy. The nano-alloy in the as-deposited state is composed of a fcc matrix of Ag nano-grains (≈6 nm), which are supersaturated by Cu, and some smaller embedded Cu rich nano-grains (≈4 nm). Heating up to 265 °C activates segregation of Cu out of the supersaturated Ag nano-grains phase, thus initiating phase separation. At T > 265 °C, the phase-separated Cu metal partially migrates to the top NML surface, thereby relaxing thermally-accumulated compressive stresses in the confined alloy nano-layers and facilitating grain coarsening of (still confined) phase-separated nano-crystallites. Further heating and annealing up to 420 °C results in complete phase separation, forming extended Ag and Cu domains with well-defined coherent Ag/AlN interfaces. The observed outflow of Cu well below the eutectic melting point of the bulk Ag-Cu alloy might provide new pathways for designing low-temperature nano-structured brazing materials.

  8. Nano-crystallization in ZnO-doped In{sub 2}O{sub 3} thin films via excimer laser annealing for thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Mami N., E-mail: f-mami@ms.naist.jp; Ishikawa, Yasuaki; Bermundo, Juan Paolo Soria; Uraoka, Yukiharu [Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Ishihara, Ryoichi; Cingel, Johan van der; Mofrad, Mohammad R. T. [Delft University of Technology, Feldmannweg 17, P.O. Box 5053, 2600 GB Delft (Netherlands); Kawashima, Emi; Tomai, Shigekazu; Yano, Koki [Idemitsu Kosan Co., Ltd., 1280 Kami-izumi, Sodegaura, Chiba, 299-0293 (Japan)

    2016-06-15

    In a previous work, we reported the high field effect mobility of ZnO-doped In{sub 2}O{sub 3} (IZO) thin film transistors (TFTs) irradiated by excimer laser annealing (ELA) [M. Fujii et al., Appl. Phys. Lett. 102, 122107 (2013)]. However, a deeper understanding of the effect of ELA on the IZO film characteristics based on crystallinity, carrier concentrations, and optical properties is needed to control localized carrier concentrations for fabricating self-aligned structures in the same oxide film and to adequately explain the physical characteristics. In the case of as-deposited IZO film used as the channel, a high carrier concentration due to a high density of oxygen vacancies was observed; such a film does not show the required TFT characteristics but can act as a conductive film. We achieved a decrease in the carrier concentration of IZO films by crystallization using ELA. This means that ELA can form localized conductive or semi-conductive areas on the IZO film. We confirmed that the reason for the carrier concentration decrease was the decrease of oxygen-deficient regions and film crystallization. The annealed IZO films showed nano-crystalline phase, and the temperature at the substrate was substantially less than the temperature limit for flexible films such as plastic, which is 50°C. This paves the way for the formation of self-aligned structures and separately formed conductive and semi-conductive regions in the same oxide film.

  9. Nano-crystallization in ZnO-doped In2O3 thin films via excimer laser annealing for thin-film transistors

    Science.gov (United States)

    Fujii, Mami N.; Ishikawa, Yasuaki; Ishihara, Ryoichi; van der Cingel, Johan; Mofrad, Mohammad R. T.; Bermundo, Juan Paolo Soria; Kawashima, Emi; Tomai, Shigekazu; Yano, Koki; Uraoka, Yukiharu

    2016-06-01

    In a previous work, we reported the high field effect mobility of ZnO-doped In2O3 (IZO) thin film transistors (TFTs) irradiated by excimer laser annealing (ELA) [M. Fujii et al., Appl. Phys. Lett. 102, 122107 (2013)]. However, a deeper understanding of the effect of ELA on the IZO film characteristics based on crystallinity, carrier concentrations, and optical properties is needed to control localized carrier concentrations for fabricating self-aligned structures in the same oxide film and to adequately explain the physical characteristics. In the case of as-deposited IZO film used as the channel, a high carrier concentration due to a high density of oxygen vacancies was observed; such a film does not show the required TFT characteristics but can act as a conductive film. We achieved a decrease in the carrier concentration of IZO films by crystallization using ELA. This means that ELA can form localized conductive or semi-conductive areas on the IZO film. We confirmed that the reason for the carrier concentration decrease was the decrease of oxygen-deficient regions and film crystallization. The annealed IZO films showed nano-crystalline phase, and the temperature at the substrate was substantially less than the temperature limit for flexible films such as plastic, which is 50°C. This paves the way for the formation of self-aligned structures and separately formed conductive and semi-conductive regions in the same oxide film.

  10. Nano Structured Plasma Spray Coating for Wear and High Temperature Corrosion Resistance Applications

    Science.gov (United States)

    Ghosh, D.; Shukla, A. K.; Roy, H.

    2014-04-01

    The nano structured coating is a major challenge today to improve the different mechanical properties, wear and high temperature corrosion resistance behaviour of different industrial alloys. This paper is a review on synthesis of nano powder, plasma spraying methods, techniques of nano structured coating by plasma spray method, mechanical properties, tribological properties and high temperature corrosion behaviour of nano structured coating. Nano structured coatings of ceramic powders/composites are being developed for wide variety of applications like boiler, turbine and aerospace industries, which requires the resistance against wear, corrosion, erosion etc. The nano sized powders are subjected to agglomeration by spray drying, after which nano structured coating can be successfully applied over the substrate. Nano structured coating shows improved mechanical wear resistance and high temperature corrosion resistance. The significant improvement of wear and corrosion resistance is mainly attributed to formation of semi molten nano zones in case of nano structured coatings. The future scope of application of nano structured coating has also been highlighted in this paper.

  11. Nano Structured Devices for Energy Generation

    DEFF Research Database (Denmark)

    Radziwon, Michal Jędrzej

    This work focuses on the enhancement of α-sexithiophene / buckminsterfullerene (α-6T / C60) inverted bilayer organic solar cell effciency by the introduction of crystalline nanostructures in the electron donor layer. In order to utilize the charge carrier mobility anisotropy in crystalline α-6T......?uorescence polarimetry and X-ray diffractometry (XRD). Layer thicknesses of inverted α-6T / C60 bilayer organic solar cells fabricated at room temperature were optimized to obtain the model device for the performance enhancement studies. By variation of the substrate temperature during deposition of α-6T, the structures...... structures in solar cells, the orientation of the individual molecules should favor charge transport perpendicular to the substrate plane. Such orientation is realized from α-6T molecules lying on the substrate, which additionally infers the preferred orientation of the transition dipole for maximal light...

  12. Effects of N2/O2 flow rate on the surface properties and biocompatibility of nano-structured TiOxNy thin films prepared by high vacuum magnetron sputtering

    Science.gov (United States)

    Saleem, Sehrish; Ahmad, R.; Ikhlaq, Uzma; Ayub, R.; Wei, Hong Jin; Rui Zhen, Xu; Peng, Hui Li; Abbas, Khizra; Chu, Paul K.

    2015-07-01

    NiTi shape memory alloys (SMA) have many biomedical applications due to their excellent mechanical and biocompatible properties. However, nickel in the alloy may cause allergic and toxic reactions, which limit some applications. In this work, titanium oxynitride films were deposited on NiTi samples by high vacuum magnetron sputtering for various nitrogen and oxygen gas flow rates. The x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) results reveal the presence of different phases in the titanium oxynitride thin films. Energy dispersive spectroscopy (EDS) elemental mapping of samples after immersion in simulated body fluids (SBF) shows that Ni is depleted from the surface and cell cultures corroborate the enhanced biocompatibility in vitro. Project supported by the Higher Education Commission, Hong Kong Research Grants Council (RGC) General Research Funds (GRF), China (Grant No. 112212) and the City University of Hong Kong Applied Research Grant (ARG), China (Grant No. 9667066).

  13. Surface Nano Structures Manufacture Using Batch Chemical Processing Methods for Tooling Applications

    DEFF Research Database (Denmark)

    Tosello, Guido; Calaon, Matteo; Gavillet, J.

    2011-01-01

    The patterning of large surface areas with nano structures by using chemical batch processes to avoid using highenergy intensive nano machining processes was investigated. The capability of different surface treatment methods of creating micro and nano structured adaptable mould inserts...... for subsequent polymer replication by injection moulding was analyzed. New tooling solutions to produce nano structured mould surfaces were investigated. Experiments based on three different chemical-based-batch techniques to establish surface nano (i.e. sub-μm) structures on large areas were performed. Three...... approaches were selected: (1) using Ø500 nm nano beads deposition for direct patterning of a 4” silicon wafer; (2) using Ø500 nm nano beads deposition as mask for 4” silicon wafer etching and subsequent nickel electroplating; (3) using the anodizing process to produce Ø500 nm structures on a 30x80 mm2...

  14. Nano-embossing technology on ferroelectric thin film Pb(Zr0.3,Ti0.7O3 for multi-bit storage application

    Directory of Open Access Journals (Sweden)

    Lu Qian

    2011-01-01

    Full Text Available Abstract In this work, we apply nano-embossing technique to form a stagger structure in ferroelectric lead zirconate titanate [Pb(Zr0.3, Ti0.7O3 (PZT] films and investigate the ferroelectric and electrical characterizations of the embossed and un-embossed regions, respectively, of the same films by using piezoresponse force microscopy (PFM and Radiant Technologies Precision Material Analyzer. Attributed to the different layer thickness of the patterned ferroelectric thin film, two distinctive coercive voltages have been obtained, thereby, allowing for a single ferroelectric memory cell to contain more than one bit of data.

  15. Effects of intermediate plasmonic structures on the performance of ultra-thin-film tandem solar cells

    Science.gov (United States)

    Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman

    2017-02-01

    Although solar cells can meet the increasing demand for energy of modern world, their usage is not as widespread as expected because of their high production cost and low efficiency. Thin-film and ultra-thin-film solar cells with single and multiple active layers are being investigated to reduce cost. Additionally, multiple active layers of different energy bandgaps are used in tandem in order to absorb the solar spectra more efficiently. However, the efficiency of ultra-thin-film tandem solar cells may suffer significantly mainly because of low photon absorption and current mismatch between active layers. In this work, we study the effects of intermediate plasmonic structures on the performance of ultra-thin-film tandem solar cells. We consider three structures| each with a top amorphous silicon layer and a bottom micro-crystalline silicon layer, and an intermediate plasmonic layer between them. The intermediate layer is either a metal layer with periodic holes or periodic metal strips or periodic metal nano-clusters. Using a finite difference time domain technique for incident AM 1.5 solar spectra, we show that these intermediate layers help to excite different plasmonic and photonic modes for different light polarizations, and thereby, increase the absorption of light significantly. We find that the short-circuit current density increases by 12%, 6%, and 9% when the intermediate plasmonic structure is a metal hole-array, strips, and nano-clusters, respectively, from that of a structure that does not have the intermediate plasmonic layer.

  16. Studies on structural properties of clay magnesium ferrite nano composite

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Manpreet, E-mail: manpreetchem@pau.edu; Singh, Mandeep [Department of Chemistry, Punjab Agricultural University, Ludhiana-141004 (India); Jeet, Kiran, E-mail: kiranjeet@pau.edu; Kaur, Rajdeep [Electron Microscopy and Nanoscience Laboratory, Punjab Agricultural University, Ludhiana-141004 (India)

    2015-08-28

    Magnesium ferrite-bentonite clay composite was prepared by sol-gel combustion method employing citric acid as complexing agent and fuel. The effect of clay on the structural properties was studied with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) Spectroscopy, Scanning electron microscopy (SEM), SEM- Energy dispersive Spectroscope (EDS) and BET surface area analyzer. Decrease in particle size and density was observed on addition of bentonite clay. The BET surface area of nano composite containing just 5 percent clay was 74.86 m{sup 2}/g. Whereas porosity increased from 40.5 per cent for the pure magnesium ferrite to 81.0 percent in the composite showing that nano-composite has potential application as an adsorbent.

  17. Si-Ge Nano-Structured with Tungsten Silicide Inclusions

    Science.gov (United States)

    Mackey, Jon; Sehirlioglu, Alp; Dynys, Fred

    2014-01-01

    Traditional silicon germanium high temperature thermoelectrics have potential for improvements in figure of merit via nano-structuring with a silicide phase. A second phase of nano-sized silicides can theoretically reduce the lattice component of thermal conductivity without significantly reducing the electrical conductivity. However, experimentally achieving such improvements in line with the theory is complicated by factors such as control of silicide size during sintering, dopant segregation, matrix homogeneity, and sintering kinetics. Samples are prepared using powder metallurgy techniques; including mechanochemical alloying via ball milling and spark plasma sintering for densification. In addition to microstructural development, thermal stability of thermoelectric transport properties are reported, as well as couple and device level characterization.

  18. Nano Structured Devices for Energy Generation

    DEFF Research Database (Denmark)

    Radziwon, Michal Jędrzej

    This work focuses on the enhancement of α-sexithiophene / buckminsterfullerene (α-6T / C60) inverted bilayer organic solar cell effciency by the introduction of crystalline nanostructures in the electron donor layer. In order to utilize the charge carrier mobility anisotropy in crystalline α-6T...... structures in solar cells, the orientation of the individual molecules should favor charge transport perpendicular to the substrate plane. Such orientation is realized from α-6T molecules lying on the substrate, which additionally infers the preferred orientation of the transition dipole for maximal light...... temperatures and a shutter were controlled by the supervisory control and data acquisition (SCADA) system, which has been implemented in LabVIEW environment. The temperatures, process pressure, and deposition rate were stored for future analysis. By variation of the substrate temperature during deposition...

  19. 'Illusional' nano-size effect due to artifacts of in-plane conductivity measurements of ultra-thin films.

    Science.gov (United States)

    Kim, Hae-Ryoung; Kim, Jong-Cheol; Lee, Kyung-Ryul; Ji, Ho-Il; Lee, Hae-Weon; Lee, Jong-Ho; Son, Ji-Won

    2011-04-01

    The nano-size effect, which indicates a drastic increase in conductivity in solid electrolyte materials of nano-scale microstructures, has drawn substantial attention in various research fields including in the field of solid oxide fuel cells (SOFCs). However, especially in the cases of the conductivity of ultra-thin films measured in an in-plane configuration, it is highly possible that the 'apparent' conductivity increase originates from electrical current flowing through other conduction paths than the thin film. As a systematic study to interrogate those measurement artifacts, we report various sources of electrical current leaks regarding in-plane conductivity measurements, specifically insulators in the measurement set-up. We have observed a 'great conductivity increase' up to an order of magnitude at a very thin thickness of a single layer yttria-stabilized zirconia (YSZ) film in a set-up with an intentional artifact current flow source. Here we propose that the nano-size effect, reported to appear in ultra-thin single layer YSZ, can be a result of misinterpretation.

  20. Thickness-dependent structural arrangement in nano-confined imidazolium-based ionic liquid films.

    Science.gov (United States)

    Rouha, Michael; Cummings, Peter T

    2015-02-14

    A fundamental understanding of interfacial processes in nano-confined ionic liquids is crucial to increase the performance of modern energy storage devices. It is well-known that interfaces between electrodes and ionic liquids exhibit structures distinct from that of the bulk liquid. Following the recent interest in these systems, we studied the structure of thin ionic liquid films confined in flexible uncharged carbon nano-pores by using fully-atomistic molecular dynamics simulations. We show that the interfacial ions self-assemble into a closely-packed chequerboard-like pattern, formed by both cations and anions in direct contact with the pore wall, and that within this structure we find changes dependent on the thickness of the confined films. At low coverages a dense layer is formed in which both the imidazolium-ring and its alkyl-tail lie parallel to the pore wall. With increasing coverage the alkyl-chains reorient perpendicular to the surface, making space for additional ions until a densified highly ordered layer is formed. This wall-induced self-patterning into interfacial layers with significantly higher than bulk density is consistent with recent experimental and theoretical studies of similar systems. This work reveals additional molecular-level details on the effect of the film-thickness on the structure and density of the ionic liquid.

  1. Nano-dot formation using self-assembled 3-mercaptopropionic acid thin films prepared by facile atmospheric-vapor-adsorption method on Au(1 1 1)

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Tohru; Kimura, Ryota; Sakai, Hideki; Abe, Masahiko; Kondoh, Hiroshi; Ohta, Toshiaki; Matsumoto, Mutsuyoshi

    2002-12-30

    Nanometer scale structures of self-assembled films consisting of 3-mercaptopropionic acid (MPA) were formed by using electric stimuli between scanning tunng microscope (STM) Au tips and gold surfaces. The obtained structures were compared with those using bare gold surfaces and hexanethiol films on Au(1 1 1) under the same conditions. X-ray photoelectron spectroscopy measurements revealed that self-assembled ultrathin films of the corresponding thiol molecules were fabricated on Au(1 1 1) by a facile atmospheric-vapor-adsorption (AVA) method without solvent. Comparison of nano-structure formation suggested that the self-assembled thin films of 3-mercatopropionic acid molecules gave nano-dots below the height of voltage pulses where gold atom emission from Au tips and surface evaporation of Au(1 1 1) take place. It was found that 3-mercaptopropionic acid films easily produced much better nano-dots on Au(1 1 1) than hexanethiol films probably due to the formation of hydrogen bonding networks and/or the reactions of 3-mercaptopropionic acid when electric pulses were applied to the films.

  2. Templated Self Assemble of Nano-Structures

    Energy Technology Data Exchange (ETDEWEB)

    Suo, Zhigang [Harvard University

    2013-04-29

    This project will identify and model mechanisms that template the self-assembly of nanostructures. We focus on a class of systems involving a two-phase monolayer of molecules adsorbed on a solid surface. At a suitably elevated temperature, the molecules diffuse on the surface to reduce the combined free energy of mixing, phase boundary, elastic field, and electrostatic field. With no template, the phases may form a pattern of stripes or disks. The feature size is on the order of 1-100 nm, selected to compromise the phase boundary energy and the long-range elastic or electrostatic interaction. Both experimental observations and our theoretical simulations have shown that the pattern resembles a periodic lattice, but has abundant imperfections. To form a perfect periodic pattern, or a designed aperiodic pattern, one must introduce a template to guide the assembly. For example, a coarse-scale pattern, lithographically defined on the substrate, will guide the assembly of the nanoscale pattern. As another example, if the molecules on the substrate surface carry strong electric dipoles, a charged object, placed in the space above the monolayer, will guide the assembly of the molecular dipoles. In particular, the charged object can be a mask with a designed nanoscale topographic pattern. A serial process (e.g., e-beam lithography) is necessary to make the mask, but the pattern transfer to the molecules on the substrate is a parallel process. The technique is potentially a high throughput, low cost process to pattern a monolayer. The monolayer pattern itself may serve as a template to fabricate a functional structure. This project will model fundamental aspects of these processes, including thermodynamics and kinetics of self-assembly, templated self-assembly, and self-assembly on unconventional substrates. It is envisioned that the theory will not only explain the available experimental observations, but also motivate new experiments.

  3. Carbon nano structures: Production and characterization

    Science.gov (United States)

    Beig Agha, Rosa

    L'objectif de ce memoire est de preparer et de caracteriser des nanostructures de carbone (CNS -- Carbon Nanostructures, en licence a l'Institut de recherche sur l'hydrogene, Quebec, Canada), un carbone avec un plus grand degre de graphitisation et une meilleure porosite. Le Chapitre 1 est une description generale des PEMFCs (PEMFC -- Polymer Electrolyte Membrane Fuel Cell) et plus particulierement des CNS comme support de catalyseurs, leur synthese et purification. Le Chapitre 2 decrit plus en details la methode de synthese et la purification des CNS, la theorie de formation des nanostructures et les differentes techniques de caracterisation que nous avons utilises telles que la diffraction aux rayons-X (XRD -- X-ray diffraction), la microscopie electronique a transmission (TEM -- transmission electron microscope ), la spectroscopie Raman, les isothermes d'adsorption d'azote a 77 K (analyse BET, t-plot, DFT), l'intrusion au mercure, et l'analyse thermogravimetrique (TGA -- thermogravimetric analysis). Le Chapitre 3 presente les resultats obtenus a chaque etape de la synthese des CNS et avec des echantillons produits a l'aide d'un broyeur de type SPEXRTM (SPEX/CertiPrep 8000D) et d'un broyeur de type planetaire (Fritsch Pulverisette 5). La difference essentielle entre ces deux types de broyeur est la facon avec laquelle les materiaux sont broyes. Le broyeur de type SPEX secoue le creuset contenant les materiaux et des billes d'acier selon 3 axes produisant ainsi des impacts de tres grande energie. Le broyeur planetaire quant a lui fait tourner et deplace le creuset contenant les materiaux et des billes d'acier selon 2 axes (plan). Les materiaux sont donc broyes differemment et l'objectif est de voir si les CNS produits ont les memes structures et proprietes. Lors de nos travaux nous avons ete confrontes a un probleme majeur. Nous n'arrivions pas a reproduire les CNS dont la methode de synthese a originellement ete developpee dans les laboratoires de l'Institut de

  4. Nanomanufacturing : nano-structured materials made layer-by-layer.

    Energy Technology Data Exchange (ETDEWEB)

    Cox, James V.; Cheng, Shengfeng; Grest, Gary Stephen; Tjiptowidjojo, Kristianto (University of New Mexico); Reedy, Earl David, Jr.; Fan, Hongyou; Schunk, Peter Randall; Chandross, Michael Evan; Roberts, Scott A.

    2011-10-01

    Large-scale, high-throughput production of nano-structured materials (i.e. nanomanufacturing) is a strategic area in manufacturing, with markets projected to exceed $1T by 2015. Nanomanufacturing is still in its infancy; process/product developments are costly and only touch on potential opportunities enabled by growing nanoscience discoveries. The greatest promise for high-volume manufacturing lies in age-old coating and imprinting operations. For materials with tailored nm-scale structure, imprinting/embossing must be achieved at high speeds (roll-to-roll) and/or over large areas (batch operation) with feature sizes less than 100 nm. Dispersion coatings with nanoparticles can also tailor structure through self- or directed-assembly. Layering films structured with these processes have tremendous potential for efficient manufacturing of microelectronics, photovoltaics and other topical nano-structured devices. This project is designed to perform the requisite R and D to bring Sandia's technology base in computational mechanics to bear on this scale-up problem. Project focus is enforced by addressing a promising imprinting process currently being commercialized.

  5. Structures of magnetized thin accretion disks

    Institute of Scientific and Technical Information of China (English)

    LI; xiaoqing(李晓卿); JI; Haisheng(季海生)

    2002-01-01

    We investigate the magnetohydrodynamic (MHD) process in thin accretion disks. Therelevant momentum as well as magnetic reduction equations in the thin disk approximation areincluded. On the basis of these equations, we examine numerically the stationary structures, includingdistributions of the surface mass density, temperature and flow velocities of a disk around a youngstellar object (YSO). The numerical results are as follows: (i) There should be an upper limit to themagnitude of magnetic field, such an upper limit corresponds to the equipartition field. For relevantmagnitude of magnetic field of the disk's interior the disk remains approximately Keplerian. (ii) Thedistribution of effective temperature T(r) is a smoothly decreasing function of radius with power 1 corresponding to the observed radiation flux density, provided that the magnetic fieldindex γ= -1/2,is suitably chosen.

  6. Optical Spectroscopy of Nano Materials and Structures

    Science.gov (United States)

    Guo, Wenhao

    broadening which is caused by the bandgap change. The experimental results confirm our speculation. When we make the nanowire straight again, the redshift disappears. It is believed that this piezoelectric effect is very important to the application of nanowires, and it would benefit the actual design and fabrication for the electronic devices for the next generation. Lastly, as for the OD case, the charge transfer mechanism occurring at the interface between graphene and ZnO QDs is investigated. We fabricate a hybrid structure by placing ZnO QDs on top of graphene. With UV light illumination on this device, it will generate electron-hole pairs inside QDs. Before they recombine, the holes will be separated and trapped into the surface states, and discharge the oxygen ions adsorbed on the surface of QDs. The unpaired electrons are then transferred to the graphene layer with a relative long lifetime. After the UV light is switched off, the oxygen molecules will re-adsorb to the QDs surface, capture electrons and recover the graphene's transport properties. Therefore, this hybrid device shows an ultrasensitive response to on-off of the UV laser, with a photoconductive gain as high as 10 7, which can be utilized for practical graphene-based UV sensors and detectors with very high responsivity. This gain can be further enhanced by another 2-3 orders by increasing source-drain voltage, shortening the sample's length, etc. It is believed that optical spectroscopy provides a convenient, efficient and useful method to study the nanomaterials and nanostructures. It is easy to set up, has no harm or degradation to the sample, and could go beyond the diffraction limit. With appropriate design and creative ideas, optical spectroscopy can be further explored, and will boost the development of nanoscience and technology. (Abstract shortened by UMI.).

  7. Nano

    DEFF Research Database (Denmark)

    Nørgaard, Bent; Engel, Lars Romann

    2007-01-01

    Gennem de sidste par år har et lille ord med et meget stort potentiale gentagende trængt sig på i den offentlige bevidsthed, det er ordet "nano". Nanovidenskab og nanoteknologi er lige nu to af de "hotteste" forskningsområder og betragtes af mange som porten til en helt ny verden af muligheder....... Muligheder, vi endnu ikke kender konsekvenserne af. Center for Kunst og Videnskabs forestilling NANO giver dig chancen for at blive bekendt med verdens mindste byggesten og idégrundlaget for nanoforskningen. Vi har skabt et rum, som på mange måder minder om et laboratorium. Rummet er forsynet med storskærme......, kolber, væsker og nanopartikler. Her vil du f.eks. opleve, hvordan forskere tilfører guld helt nye egenskaber. Forestillingen veksler mellem kemiske arbejdsdemonstrationer, stemningsskabende musik og livlig debat på storskærme mellem eksperter. NANO opfordrer publikum til at tage stilling til forskningen...

  8. Band engineering of amorphous silicon ruthenium thin film and its near-infrared absorption enhancement combined with nano-holes pattern on back surface of silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Anran; Zhong, Hao [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Li, Wei, E-mail: wli@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Gu, Deen; Jiang, Xiangdong [School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Jiang, Yadong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2016-10-30

    Highlights: • The increase of Ru concentration leads to a narrower bandgap of a-Si{sub 1-x}Ru{sub x} thin film. • The absorption coefficient of a-Si{sub 1-x}Ru{sub x} is higher than that of SiGe. • A double-layer absorber comprising of a-Si{sub 1-x}Ru{sub x} film and Si nano-holes layer is achieved. - Abstract: Silicon is widely used in semiconductor industry but has poor performance in near-infrared photoelectronic devices because of its bandgap limit. In this study, a narrow bandgap silicon rich semiconductor is achieved by introducing ruthenium (Ru) into amorphous silicon (a-Si) to form amorphous silicon ruthenium (a-Si{sub 1-x}Ru{sub x}) thin films through co-sputtering. The increase of Ru concentration leads to an enhancement of light absorption and a narrower bandgap. Meanwhile, a specific light trapping technique is employed to realize high absorption of a-Si{sub 1-x}Ru{sub x} thin film in a finite thickness to avoid unnecessary carrier recombination. A double-layer absorber comprising of a-Si{sub 1-x}Ru{sub x} thin film and silicon random nano-holes layer is formed on the back surface of silicon substrates, and significantly improves near-infrared absorption while the leaky light intensity is less than 5%. This novel absorber, combining narrow bandgap thin film with light trapping structure, may have a potential application in near-infrared photoelectronic devices.

  9. Imprinted and injection-molded nano-structured optical surfaces

    Science.gov (United States)

    Christiansen, Alexander B.; Højlund-Nielsen, Emil; Clausen, Jeppe; Caringal, Gideon P.; Mortensen, N. Asger; Kristensen, Anders

    2013-09-01

    Inspired by nature, nano-textured surfaces have attracted much attention as a method to realize optical surface functionality. The moth-eye antireflective structure and the structural colors of Morpho butterflies are well- known examples used for inspiration for such biomimetic research. In this paper, nanostructured polymer surfaces suitable for up-scalable polymer replication methods, such as imprinting/embossing and injection-molding, are discussed. The limiting case of injection-moulding compatible designs is investigated. Anti-reflective polymer surfaces are realized by replication of Black Silicon (BSi) random nanostructure surfaces. The optical transmission at normal incidence is measured for wavelengths from 400 nm to 900 nm. For samples with optimized nanostructures, the reflectance is reduced by 50 % compared to samples with planar surfaces. The specular and diffusive reflection of light from polymer surfaces and their implication for creating structural colors is discussed. In the case of injection-moulding compatible designs, the maximum reflection of nano-scale textured surfaces cannot exceed the Fresnel reflection of a corresponding flat polymer surface, which is approx. 4 % for normal incidence. Diffraction gratings provide strong color reflection defined by the diffraction orders. However, the apperance varies strongly with viewing angles. Three different methods to address the strong angular-dependence of diffraction grating based structural color are discussed.

  10. Self-organized nano-structuring of CoO islands on Fe(001)

    Science.gov (United States)

    Brambilla, A.; Picone, A.; Giannotti, D.; Riva, M.; Bussetti, G.; Berti, G.; Calloni, A.; Finazzi, M.; Ciccacci, F.; Duò, L.

    2016-01-01

    The realization of nanometer-scale structures through bottom-up strategies can be accomplished by exploiting a buried network of dislocations. We show that, by following appropriate growth steps in ultra-high vacuum molecular beam epitaxy, it is possible to grow nano-structured films of CoO coupled to Fe(001) substrates, with tunable sizes (both the lateral size and the maximum height scale linearly with coverage). The growth mode is discussed in terms of the evolution of surface morphology and chemical interactions as a function of the CoO thickness. Scanning tunneling microscopy measurements reveal that square mounds of CoO with lateral dimensions of less than 25 nm and heights below 10 atomic layers are obtained by growing few-nanometers-thick CoO films on a pre-oxidized Fe(001) surface covered by an ultra-thin Co buffer layer. In the early stages of growth, a network of misfit dislocations develops, which works as a template for the CoO nano-structuring. From a chemical point of view, at variance with typical CoO/Fe interfaces, neither Fe segregation at the surface nor Fe oxidation at the buried interface are observed, as seen by Auger electron spectroscopy and X-ray Photoemission Spectroscopy, respectively.

  11. Formation of nano-crystalline C{sub 3}N{sub 4} thin films on stainless steel from hexamethylenetetramine and urea using simple sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, Md. Nizam, E-mail: nizam3472@yahoo.com [Department of Chemistry, Shahjalal University of Science and Technology, Sylhet-3114 (Bangladesh); Yang, Yong Suk, E-mail: ysyang@pusan.ac.kr [College of Nanoscience and Nanotechnology, RCDAMP, Pusan National University, Pusan 609-735 (Korea, Republic of)

    2013-12-02

    Nano-crystalline C{sub 3}N{sub 4} thin films have been deposited on stainless steel (SS) substrates from hexamethylenetetramine (HMTA) and urea separately using simple sol–gel method. For that purpose hot-dip coating processes were carried out. The coated specimens were annealed at 800 °C in N{sub 2}. The samples were analyzed using field emission scanning electron microscopy, nanoindenter, X-ray photoelectron spectroscopy and X-ray diffraction. The deposits show C{sub 3}N{sub 4} with clear hexagonal morphology and size range of 50–500 nm. The hardness values of the synthesized films show 2.74–4.35 times higher than that of SS. The hardness and Young's modulus of the films synthesized from HMTA show the highest values; 16.10 and 394.29 GPa, respectively. This significant achievement of the production of nano-crystalline C{sub 3}N{sub 4} from inexpensive sources and simple methods at ambient pressure opens up a door for its low cost production on SS for a wide range of applications. Irrespective of the sources with different chemical structures we got similar product, which implies that different sources of carbon and nitrogen might be used with our methods of sol–gel deposition. - Highlights: • Formation of nano-crystalline C{sub 3}N{sub 4} thin films with a low cost and simple sol–gel method • Uses of inexpensive materials, like steel, hexamethylenetetramine and urea • Repeatability of this method using different precursors for crystalline C{sub 3}N{sub 4} thin films.

  12. High energy density capacitors using nano-structure multilayer technology

    Energy Technology Data Exchange (ETDEWEB)

    Barbee, T.W. Jr.; Johnson, G.W.; O`Brien, D.W.

    1992-08-01

    Today, many pulse power and industrial applications are limited by capacitor performance. While incremental improvements are anticipated from existing capacitor technologies, significant advances are needed in energy density to enable these applications for both the military and for American economic competitiveness. We propose a program to research and develop a novel technology for making high voltage, high energy density capacitors. Nano-structure multilayer technologies developed at LLNL may well provide a breakthrough in capacitor performance. Our controlled sputtering techniques are capable of laying down extraordinarily smooth sub-micron layers of dielectric and conductor materials. With this technology, high voltage capacitors with an order of magnitude improvement in energy density may be achievable. Well-understood dielectrics and new materials will be investigated for use with this technology. Capacitors developed by nano-structure multilayer technology are inherently solid state, exhibiting extraordinary mechanical and thermal properties. The conceptual design of a Notepad capacitor is discussed to illustrate capacitor and capacitor bank design and performance with this technology. We propose a two phase R&D program to address DNA`s capacitor needs for electro-thermal propulsion and similar pulse power programs. Phase 1 will prove the concept and further our understanding of dielectric materials and design tradeoffs with multilayers. Nano-structure multilayer capacitors will be developed and characterized. As our materials research and modeling prove successful, technology insertion in our capacitor designs will improve the possibility for dramatic performance improvements. In Phase 2, we will make Notepad capacitors, construct a capacitor bank and demonstrate its performance in a meaningful pulse power application. We will work with industrial partners to design full scale manufacturing and move this technology to industry for volume production.

  13. Application of Plane Wave Method to the Calculation of Electronic States of Nano-Structures

    Institute of Scientific and Technical Information of China (English)

    LI Shu-Shen; XIA Jian-Bai

    2006-01-01

    @@ The electronic states of nano-structures are studied in the framework of effective-mass envelope-function theory using the plane wave basis. The barrier width and the number of plane waves are proposed to be 2.5 times the effective Bohr radius and 15n, respectively, for n-dimensional nano-structures (n = 1, 2, 3). Our proposals can be widely applied in the design of various nano-structure devices.

  14. Efficient application of nano-TiO2 thin films in the photocatalytic removal of Alizarin Yellow from aqueous solutions

    Science.gov (United States)

    Tiwari, Diwakar; Lalhriatpuia, C.; Lalhmunsiama; Lee, Seung-Mok; Kong, Sung-Ho

    2015-10-01

    The aim of this investigation is to obtain thin films of nano-TiO2 on a borosilicate glass substrate using sol-gel template method. The thin film was immobilized with and without polyethylene glycol as filler media and annealed at 500 °C. Further, thin films were characterized by the IR, XRD, XRF and XPS analytical methods. The surface morphology of these films was obtained by the FE-SEM images and the BET specific surface area and pore sizes were obtained. The nano-TiO2 was, perhaps, formed a nanopillar onto the substrate. The thin films were successfully employed in the photocatalytic degradation of Alizarin Yellow (AY), an azo dye, from aqueous solutions using the UV-light irradiation under batch reactor operations. Various physico-chemical parametric studies, viz., effect of pH, Alizarin Yellow concentration and interfering ions were studied to deduce the mechanism involved in photocatalytic degradation of this pollutant. The time dependence degradation of Alizarin Yellow was provided to demonstrate the kinetics of degradation of this pollutant from aqueous solutions. It was observed that the degradation of Alizarin Yellow followed pseudo-first-order rate kinetics. Study was further extended with total organic carbon measurement using TOC analyser to demonstrate an apparent mineralization of Alizarin Yellow from aqueous solutions. The presence of several interfering ions or even rad OH scavengers suppressed the photo-catalytic action of thin films in AY degradation from aqueous solutions.

  15. Hybridized Nano-Structure Composed of Metal and Polydiacetylene

    Institute of Scientific and Technical Information of China (English)

    H. Oikawa; A. Masuhara; T. Onodera; H. Kasai; H. Nakanishi

    2005-01-01

    @@ 1Introduction Polydiacetylene (PDA) is one of the promising candidates for organic third-order nonlinear optical (NLO) material, due to fast optical responsibility and easy processability in comparison with semiconductors etc. The magnitude of NLO property, however, is not still sufficient for the devices applications. Neeves, et al[1] theoretically predicted the enhancement of NLO property for core-shell type hybridized nanocrystal (NC) composed of PDA and metal. In the present study, we have prepared the two kinds of core-shell type hybridized nano-structure, and investigated their optical properties.

  16. Electrical, thermal, catalytic and magnetic properties of nano-structured materials and their applications

    Science.gov (United States)

    Liu, Zuwei

    Nanotechnology is a subject that studies the fabrication, properties, and applications of materials on the nanometer-scale. Top-down and bottom-up approaches are commonly used in nano-structure fabrication. The top-down approach is used to fabricate nano-structures from bulk materials by lithography, etching, and polishing etc. It is commonly used in mechanical, electronic, and photonic devices. Bottom-up approaches fabricate nano-structures from atoms or molecules by chemical synthesis, self-assembly, and deposition, such as sol-gel processing, molecular beam epitaxy (MBE), focused ion beam (FIB) milling/deposition, chemical vapor deposition (CVD), and electro-deposition etc. Nano-structures can have several different dimensionalities, including zero-dimensional nano-structures, such as fullerenes, nano-particles, quantum dots, nano-sized clusters; one-dimensional nano-structures, such as carbon nanotubes, metallic and semiconducting nanowires; two-dimensional nano-structures, such as graphene, super lattice, thin films; and three-dimensional nano-structures, such as photonic structures, anodic aluminum oxide, and molecular sieves. These nano-structured materials exhibit unique electrical, thermal, optical, mechanical, chemical, and magnetic properties in the quantum mechanical regime. Various techniques can be used to study these properties, such as scanning probe microscopy (SPM), scanning/transmission electron microscopy (SEM/TEM), micro Raman spectroscopy, etc. These unique properties have important applications in modern technologies, such as random access memories, display, solar energy conversion, chemical sensing, and bio-medical devices. This thesis includes four main topics in the broad area of nanoscience: magnetic properties of ferro-magnetic cobalt nanowires, plasmonic properties of metallic nano-particles, photocatalytic properties of titanium dioxide nanotubes, and electro-thermal-optical properties of carbon nanotubes. These materials and their

  17. Strong thin membrane structure. [solar sails

    Science.gov (United States)

    Frazer, R. E. (Inventor)

    1979-01-01

    A continuous process is described for producing strong lightweight structures for use as solar sails for spacecraft propulsion by radiation pressure. A thin reflective coating, such as aluminum, is applied to a rotating cylinder. A nylon mesh, applied over the aluminum coating, is then coated with a polymerizing material such as a para-xylylene monomer gas to polymerize as a film bound to the mesh and the aluminum. An emissivity increasing material such as chromium or silicon monoxide is applied to the polymer film to disperse such material colloidally into the growing polymer film, or to the final polymer film. The resulting membrane structure is then removed from the cylinder. Alternately, the membrane structure can be formed by etching a substrate in the form of an organic film such as a polymide, or a metal foil, to remove material from the substrate and reduce its thickness. A thin reflective coating (aluminum) is applied on one side of the substrate, and an emissivity increasing coating is applied on the reverse side of the substrate.

  18. Thin structured rigid body for acoustic absorption

    Science.gov (United States)

    Starkey, T. A.; Smith, J. D.; Hibbins, A. P.; Sambles, J. R.; Rance, H. J.

    2017-01-01

    We present a thin acoustic metamaterial absorber, comprised of only rigid metal and air, that gives rise to near unity absorption of airborne sound on resonance. This simple, easily fabricated, robust structure comprising a perforated metal plate separated from a rigid wall by a deeply subwavelength channel of air is an ideal candidate for a sound absorbing panel. The strong absorption in the system is attributed to the thermo-viscous losses arising from a sound wave guided between the plate and the wall, defining the subwavelength channel.

  19. Integrated Surface and Mechanical Characterization of Freestanding Biological and Other Nano-Structures Using Atomic Force Microscopy

    Science.gov (United States)

    Wang, Xin

    This dissertation is focused on surface and mechanical characterization of freestanding biological and other nano-structures using atomic force microscopy including two parts: cell mechanics and nano-structure mechanics. The main purpose of this work is to investigate how the nano- / micro-scale mechanical properties affect macro-scale function. In cancer cells, efficacy of drug delivery is oftentimes declined due to the thick dendritic network of oligosaccharide mucin chains on the cell surface. AFM is used to measure the force needed to pierce the mucin layer to reach the cell surface. A pool of ovarian, pancreatic, lung, colorectal and breast cancer cells are characterized. The studies offer additional support for the development of clinical and pharmaceutical approaches to combat mucin over-expression in tumors during cancer chemotherapy. Macroscopic adhesion-aggregation and subsequent transportation of microorganisms in porous medium are closely related to the microscopic deformation and adhesion mechanical properties. The classical Tabor's parameter is modified. Multiple bacterial strains are characterized in terms of aggregates size, aggregation index and transportation kinetics. AFM is employed to obtain the microscopic coupled adhesion-deformation properties. The strong correlation between Tabor's parameter and aggregation-deposition-transportation suggests the AFM characterization is capable of making reliable predication of macroscopic behavior. A novel "nano-cheese-cutter" is fabricated on tipless AFM cantilever to measure elastic modulus and interfacial adhesion of a 1-D freestanding nano-structure. A single electrospun fiber is attached to the free end of AFM cantilever, while another fiber is similarly prepared on a mica substrate in an orthogonal direction. An external load is applied to deform the two fibers into complementary V-shapes. This work is extended to investigate the interfacial adhesion energy between dissimilar materials. SWCNT thin

  20. Enzymes as Biodevelopers for Nano- And Micropatterned Bicomponent Biopolymer Thin Films.

    Science.gov (United States)

    Niegelhell, Katrin; Süßenbacher, Michael; Jammernegg, Katrin; Ganner, Thomas; Schwendenwein, Daniel; Schwab, Helmut; Stelzer, Franz; Plank, Harald; Spirk, Stefan

    2016-11-14

    The creation of nano- and micropatterned polymer films is a crucial step for innumerous applications in science and technology. However, there are several problems associated with environmental aspects concerning the polymer synthesis itself, cross-linkers to induce the patterns as well as toxic solvents used for the preparation and even more important development of the films (e.g., chlorobenzene). In this paper, we present a facile method to produce micro- and nanopatterned biopolymer thin films using enzymes as so-called biodevelopers. Instead of synthetic polymers, naturally derived ones are employed, namely, poly-3-hydroxybutyrate and a cellulose derivative, which are dissolved in a common solvent in different ratios and subjected to spin coating. Consequently, the two biopolymers undergo microphase separation and different domain sizes are formed depending on the ratio of the biopolymers. The development step proceeds via addition of the appropriate enzyme (either PHB-depolymerase or cellulase), whereas one of the two biopolymers is selectively degraded, while the other one remains on the surface. In order to highlight the enzymatic development of the films, video AFM studies have been performed in real time to image the development process in situ as well as surface plasmon resonance spectroscopy to determine the kinetics. These studies may pave the way for the use of enzymes in patterning processes, particularly for materials intended to be used in a physiological environment.

  1. Optical and Electrical Investigation of ZnO Nano-Wire Array to Micro-Flower from Hierarchical Nano-Rose Structures

    NARCIS (Netherlands)

    Pal, Kaushik; Zhan, Bihong; Ma, Xiao; Wang, Guoping; Schirhagl, Romana; Murgasen, Priya

    2016-01-01

    We have demonstrated a simple solvo-chemical and solvo-thermal route to design various nano-structures growth of zinc oxide (ZnO). The shapes and morphologies can be easily controlled by using different ambient conditions. We successfully fabricated ZnO nano-wires array on ITO substrate. Those nano-

  2. Optical and Electrical Investigation of ZnO Nano-Wire Array to Micro-Flower from Hierarchical Nano-Rose Structures

    NARCIS (Netherlands)

    Pal, Kaushik; Zhan, Bihong; Ma, Xiao; Wang, Guoping; Schirhagl, Romana; Murgasen, Priya

    2016-01-01

    We have demonstrated a simple solvo-chemical and solvo-thermal route to design various nano structures growth of zinc oxide (ZnO). The shapes and morphologies can be easily controlled by using different ambient conditions. We successfully fabricated ZnO nano-wires array on ITO substrate. Those nano-

  3. Investigation the Al–Fe–Cr–Ti nano composites structures with using XRD and AFM techniques

    Indian Academy of Sciences (India)

    Ali Bahari; Aref Sadeghi Nik; Mandana Roodbari; Nordin Mirnia

    2012-12-01

    The performance of multilayers has been widely investigated in metal/metal systems. Shrinking this system down to less than 10 nm dislocation blocking occurs. We should thus try to find a way to get a structure with less dislocation, and/or strain because low diffusivity ultra high vacuum chamber is the basic requirements for growing ultra thin films and nano scale materials. We used William–Hall relation based on Scherr equation in X-ray powder spectrum and drawn the stress–strain diagrams. It shows that Al–Fe–Cr–Ti composites have very low diffusivity and equilibrium solubility in Al (0.05 at.% Fe, >0.02 at.% Cr, and >0.3 at.% Ti). Al–Ti– Fe–Cr composite powders have also been prepared from sol–gel method starting from elemental powders at both ambient and elevated temperatures. The obtained results from XRD (X-ray Diffraction), AFM (Atomic Force Microscopy) and X-ray powder techniques indicate that nano-grains with 0.03 at %Cr can cause a reduction of leakage current through the SS chamber due to its amorphous structure.

  4. Direct-Write Fabrication of Cellulose Nano-Structures via Focused Electron Beam Induced Nanosynthesis

    Science.gov (United States)

    Ganner, Thomas; Sattelkow, Jürgen; Rumpf, Bernhard; Eibinger, Manuel; Reishofer, David; Winkler, Robert; Nidetzky, Bernd; Spirk, Stefan; Plank, Harald

    2016-09-01

    In many areas of science and technology, patterned films and surfaces play a key role in engineering and development of advanced materials. Here, we introduce a new generic technique for the fabrication of polysaccharide nano-structures via focused electron beam induced conversion (FEBIC). For the proof of principle, organosoluble trimethylsilyl-cellulose (TMSC) thin films have been deposited by spin coating on SiO2 / Si and exposed to a nano-sized electron beam. It turns out that in the exposed areas an electron induced desilylation reaction takes place converting soluble TMSC to rather insoluble cellulose. After removal of the unexposed TMSC areas, structured cellulose patterns remain on the surface with FWHM line widths down to 70 nm. Systematic FEBIC parameter sweeps reveal a generally electron dose dependent behavior with three working regimes: incomplete conversion, ideal doses and over exposure. Direct (FT-IR) and indirect chemical analyses (enzymatic degradation) confirmed the cellulosic character of ideally converted areas. These investigations are complemented by a theoretical model which suggests a two-step reaction process by means of TMSC → cellulose and cellulose → non-cellulose material conversion in excellent agreement with experimental data. The extracted, individual reaction rates allowed the derivation of design rules for FEBIC parameters towards highest conversion efficiencies and highest lateral resolution.

  5. Low cost and high performance light trapping structure for thin-film solar cells

    CERN Document Server

    Wang, DongLin; Su, Gang

    2015-01-01

    Nano-scaled dielectric and metallic structures are popular light tapping structures in thin-film solar cells. However, a large parasitic absorption in those structures is unavoidable. Most schemes based on such structures also involve the textured active layers that may bring undesirable degradation of the material quality. Here we propose a novel and cheap light trapping structure based on the prism structured SiO2 for thin-film solar cells, and a flat active layer is introduced purposefully. Such a light trapping structure is imposed by the geometrical shape optimization to gain the best optical benefit. By examining our scheme, it is disclosed that the conversion efficiency of the flat a-Si:H thin-film solar cell can be promoted to exceed the currently certified highest value. As the cost of SiO2-based light trapping structure is much cheaper and easier to fabricate than other materials, this proposal would have essential impact and wide applications in thin-film solar cells.

  6. Plasma-enhanced Deposition of Nano-Structured Carbon Films

    Institute of Scientific and Technical Information of China (English)

    Yang Qiaoqin (杨巧勤); Xiao Chijin (肖持进); A. Hirose

    2005-01-01

    By pre-treating substrate with different methods and patterning the catalyst, selective and patterned growth of diamond and graphitic nano-structured carbon films have been realized through DC Plasma-Enhanced Hot Filament Chemical Vapor Deposition (PE-HFCVD).Through two-step processing in an HFCVD reactor, novel nano-structured composite diamond films containing a nanocrystalline diamond layer on the top of a nanocone diamond layer have been synthesized. Well-aligned carbon nanotubes, diamond and graphitic carbon nanocones with controllable alignment orientations have been synthesized by using PE-HFCVD. The orientation of the nanostructures can be controlled by adjusting the working pressure. In a Microwave Plasma Enhanced Chemical Vapor Deposition (MW-PECVD) reactor, high-quality diamond films have been synthesized at low temperatures (310 ℃~550 ℃) without adding oxygen or halogen gas in a newly developed processing technique. In this process, carbon source originates from graphite etching, instead of hydrocarbon. The lowest growth temperature for the growth of nanocrystalline diamond films with a reasonable growth rate without addition of oxygen or halogen is 260 ℃.

  7. Structure-­mediated nano-­biophotonics

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Villangca, Mark Jayson; Bañas, Andrew Rafael;

    2015-01-01

    The synergy between photonics, nanotechnology and biotechnology is spawning the emerging fields of nano-biotechnology and nano-biophotonics. Photonic innovations already hurdle the diffraction barrier for imaging with nanoscopic resolutions. However, scientific hypothesis testing demands tools...

  8. Preparation of biomimetic nano-structured films with multi-scale roughness

    Science.gov (United States)

    Shelemin, A.; Nikitin, D.; Choukourov, A.; Kylián, O.; Kousal, J.; Khalakhan, I.; Melnichuk, I.; Slavínská, D.; Biederman, H.

    2016-06-01

    Biomimetic nano-structured films are valuable materials in various applications. In this study we introduce a fully vacuum-based approach for fabrication of such films. The method combines deposition of nanoparticles (NPs) by gas aggregation source and deposition of overcoat thin film that fixes the nanoparticles on a surface. This leads to the formation of nanorough surfaces which, depending on the chemical nature of the overcoat, may range from superhydrophilic to superhydrophobic. In addition, it is shown that by proper adjustment of the amount of NPs it is possible to tailor adhesive force on superhydrophobic surfaces. Finally, the possibility to produce NPs in a wide range of their size (45-240 nm in this study) makes it possible to produce surfaces not only with single scale roughness, but also with bi-modal or even multi-modal character. Such surfaces were found to be superhydrophobic with negligible water contact angle hysteresis and hence truly slippery.

  9. Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope

    CERN Document Server

    Suran, Swathi; Raghavan, Srinivasan; Varma, Manoj M

    2015-01-01

    Most methods for optical visualization beyond the diffraction limit rely on fluorescence emission by molecular tags. Here, we report a method for visualization of nanostructures down to a few nanometers using a conventional bright-field microscope without requiring additional molecular tags such as fluorophores. The technique, Bright-field Nanoscopy, is based on the strong thickness dependent color of ultra-thin germanium on an optically thick gold film. We demonstrate the visualization of grain boundaries in chemical vapour deposited single layer graphene and the detection of single 40 nm Ag nanoparticles. We estimate a size detection limit of about 2 nm using this technique. In addition to visualizing nano-structures, this technique can be used to probe fluid phenomena at the nanoscale, such as transport through 2D membranes. We estimated the water transport rate through a 1 nm thick polymer film using this technique, as an illustration. Further, the technique can also be extended to study the transport of ...

  10. Structured SiCu thin films in LiB as anodes

    Energy Technology Data Exchange (ETDEWEB)

    Polat, B.D., E-mail: bpolat@itu.edu.tr [Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, Istanbul 34469 (Turkey); Eryilmaz, O.L.; Erck, R. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Keleş, O., E-mail: ozgulkeles@itu.edu.tr [Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, Istanbul 34469 (Turkey); Erdemir, A. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Amine, K. [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2014-12-01

    Both helical and inclined columnar Si–10 at.% Cu structured thin films were deposited on Cu substrates using glancing angle deposition (GLAD) technique. In order to deposit Cu and Si two evaporation sources were used. Ion assistance was utilized in the first 5 min of the GLAD to enhance the adhesion and the density of the films. These films were characterized by thin film XRD, GDOES, SEM, and EDS. Electrochemical characterizations were made by testing the thin films as anodes in half-cells for 100 cycles. The results showed that the columnar SiCu thin film delivered 2200 mAh g{sup −1}, where the helical one exhibited 2600 mAh g{sup −1}, and, their initial coulombic efficiencies were found to be 38%–50% respectively. For the columnar and the helical thin film anodes, sustainable 520 and 800 mAh g{sup −1} with 90% and 99% coulombic efficiencies were achieved for 100 cycles. These sustainable capacities showed the importance of the thin film structure having nano-sized crystals and amorphous particles. The higher surface area of the helices increases the capacity of the electrode because the contact area of the thin film anode with Li ions is increased, and the polarization which otherwise forms on the anode surface due to SEI formation is decreased. In addition, because of larger interspaces between the helices the ability of the anode to accommodate the volumetric changes is improved, which results in a higher coulombic efficiency and capacity retention during cycling test. - Highlights: • Cu and Si atoms were co-evaporated to form composite thin film. • GLAD is an alternative method to form new electrodes for LIB. • Uses of the composite helices and nanocolumns as anodes were shown experimentally. • IAD was used to improve the adhesion of the structured thin films. • High surface area, porosities and Cu presence improve the Si anode performance.

  11. Correlation between microstructure and optical properties of nano-crystalline TiO{sub 2} thin films prepared by sol-gel dip coating

    Energy Technology Data Exchange (ETDEWEB)

    Mechiakh, R., E-mail: raouf_mechiakh@yahoo.fr [Departement de Medecine, Faculte de Medecine, Universite Hadj Lakhdar, Batna (Algeria); Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP.95, Hammam-Lif 2050 (Tunisia); Laboratoire de Ceramiques, Universite Mentouri Constantine (Algeria); Sedrine, N. Ben; Chtourou, R. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP.95, Hammam-Lif 2050 (Tunisia); Bensaha, R. [Laboratoire de Ceramiques, Universite Mentouri Constantine (Algeria)

    2010-11-15

    Titanium dioxide thin films have been prepared from tetrabutyl-orthotitanate solution and methanol as a solvent by sol-gel dip coating technique. TiO{sub 2} thin films prepared using a sol-gel process have been analyzed for different annealing temperatures. Structural properties in terms of crystal structure were investigated by Raman spectroscopy. The surface morphology and composition of the films were investigated by atomic force microscopy (AFM). The optical transmittance and reflectance spectra of TiO{sub 2} thin films deposited on silicon substrate were also determined. Spectroscopic ellipsometry study was used to determine the annealing temperature effect on the optical properties and the optical gap of the TiO{sub 2} thin films. The results show that the TiO{sub 2} thin films crystallize in anatase phase between 400 and 800 deg. C, and into the anatase-rutile phase at 1000 deg. C, and further into the rutile phase at 1200 deg. C. We have found that the films consist of titanium dioxide nano-crystals. The AFM surface morphology results indicate that the particle size increases from 5 to 41 nm by increasing the annealing temperature. The TiO{sub 2} thin films have high transparency in the visible range. For annealing temperatures between 1000 and 1400 deg. C, the transmittance of the films was reduced significantly in the wavelength range of 300-800 nm due to the change of crystallite phase and composition in the films. We have demonstrated as well the decrease of the optical band gap with the increase of the annealing temperature.

  12. Inkjet-based deposition of polymer thin films enabled by a lubrication model incorporating nano-scale parasitics

    Science.gov (United States)

    Singhal, Shrawan; Meissl, Mario J.; Bonnecaze, Roger T.; Sreenivasan, S. V.

    2013-09-01

    Thin film lubrication theory has been widely used to model multi-scale fluid phenomena. Variations of the same have also found application in fluid-based manufacturing process steps for micro- and nano-scale devices over large areas where a natural disparity in length scales exists. Here, a novel inkjet material deposition approach has been enabled by an enhanced thin film lubrication theory that accounts for nano-scale substrate parasitics. This approach includes fluid interactions with a thin flexible superstrate towards a new process called Jet and Coat of Thin-films (JCT). Numerical solutions of the model have been verified, and also validated against controlled experiments of polymer film deposition with good agreement. Understanding gleaned from the experimentally validated model has then been used to facilitate JCT process synthesis resulting in substantial reduction in the influence of parasitics and a concomitant improvement in the film thickness uniformity. Polymer films ranging from 20 to 500 nm mean thickness have been demonstrated with standard deviation of less than 2% of the mean film thickness. The JCT process offers advantages over spin coating which is not compatible with roll-to-roll processing and large area processing for displays. It also improves over techniques such as knife edge coating, slot die coating, as they are limited in the range of thicknesses of films that can be deposited without compromising uniformity.

  13. Structure and Properties of Modified Unsaturated Polyester Resin by Nano-TiO2

    Institute of Scientific and Technical Information of China (English)

    Ying XU; Mingli LI; Yan GUO; Fengji LU

    2003-01-01

    The nano-TiO2/unsaturated polyester resin (referred to as nano-TiO2/UPR hereafter) was prepared with the "reaction method", by which a chemical bond generated between nano-TiO2 and UP was inserted in the UP long chain. The performance of the nano-TiO2/UPR was determined by such a new structure. The research results showed that the reactivity of nano-TiO2/UPR is higher than that of UPR. The impact strength and bending strength of nanoTiO2/UPR are greatly enhanced as compared with that of UPR. Thermal resistance and dielectric property of nano-TiO2/UPR are the same as that of UPR.

  14. Preparation, structural and optical characterization of nanocrystalline CdS thin film

    Science.gov (United States)

    Abdel-Galil, A.; Balboul, M. R.; Atta, A.; Yahia, I. S.; Sharaf, A.

    2014-08-01

    Nano-structured CdS thin film was deposited onto a glass substrate by an electron beam evaporation technique at room temperature from a powder prepared by a hydrothermal method. The morphology and structural properties of the as-deposited film were characterized using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The AFM morphology study confirms that the CdS thin film has nano-sized grains and a dense morphology. The mean particle size that resulted from XRD analyses was 8.4 nm. Also, the XRD patterns show that CdS powder and thin film have hexagonal wurtzite type structure with a preferred c-axis orientation along (002) plane. The refractive index and the film thickness were obtained using the Swanepoel method from transmission spectrum. The optical band gap was calculated from the absorption spectrum, and was found to be 2.41 eV corresponding to direct optical transition. The dispersion of the refractive index was explained using a single oscillator model. The dielectric relaxation time and the optical conductivity were determined and studied with photon energy.

  15. Band engineering of amorphous silicon ruthenium thin film and its near-infrared absorption enhancement combined with nano-holes pattern on back surface of silicon substrate

    Science.gov (United States)

    Guo, Anran; Zhong, Hao; Li, Wei; Gu, Deen; Jiang, Xiangdong; Jiang, Yadong

    2016-10-01

    Silicon is widely used in semiconductor industry but has poor performance in near-infrared photoelectronic devices because of its bandgap limit. In this study, a narrow bandgap silicon rich semiconductor is achieved by introducing ruthenium (Ru) into amorphous silicon (a-Si) to form amorphous silicon ruthenium (a-Si1-xRux) thin films through co-sputtering. The increase of Ru concentration leads to an enhancement of light absorption and a narrower bandgap. Meanwhile, a specific light trapping technique is employed to realize high absorption of a-Si1-xRux thin film in a finite thickness to avoid unnecessary carrier recombination. A double-layer absorber comprising of a-Si1-xRux thin film and silicon random nano-holes layer is formed on the back surface of silicon substrates, and significantly improves near-infrared absorption while the leaky light intensity is less than 5%. This novel absorber, combining narrow bandgap thin film with light trapping structure, may have a potential application in near-infrared photoelectronic devices.

  16. Nano-sized Thin Films Fabricated by Ion Beam Sputtering and Its Properties

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nanoscale thick amorphous Ni-Cr alloy thin films were fabricated by low-energy ion beam sputtering technology; then the as-deposited samples experienced rapid thermal process to realize the transformation from amorphous to crystalline state. The film thickness was measured with α-stylus surface profiler, the structure and the compositions of the films were confirmed by low angle X-ray diffraction and scanning auger electron microprobe respectively, and the surface topography was characterized by scanning electron microscope and scanning probe microscope. Electrical property of the films was measured by fourpoint probe. The experimental results illustrate that the combined processes of ion beam sputtering and rapid thermal process are effective for fabrication nanoscale Ni-Cr alloy thin film with good properties.

  17. Swift heavy ion induced surface modifications in nano-crystalline Li-Mg ferrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Sanjukta [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India) and Department of Physics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009 (India)]. E-mail: sanjukta@iopb.res.in; Ganesan, V. [Inter University Consortium for DAE facilities, Khandwa Road, Indore 452017 (India); Khan, S.A. [Nuclear Science Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Ayyub, Pushan [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Kumar, Nitendar [Solid State Physics Laboratory, DRDO, Lucknow Road, Delhi 110054 (India)

    2006-09-30

    The swift heavy ion (190 MeV Au{sup 14+}) induced modifications in surface morphologies of the nanocrystals of ferrite thin films have been extensively studied through the images of atomic force microscopy (AFM). In most of the irradiated films significant features like, the ditch and dike structures, have been observed through out the surface. We try to explain the observed changes on the basis of thermal spike model followed by momentum transfer induced lateral mass transport. In addition to these changes some new and interesting features have been noticed after irradiation in 8F and 9F ferrite thin films. These new features are attributed to sputtering phenomenon due to the presence of defects like latent tracks.

  18. Nano structured materials studied by coherent X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Gulden, Johannes

    2013-03-15

    Structure determination with X-rays in crystallography is a rapidly evolving field. Crystallographic methods for structure determination are based on the assumptions about the crystallinity of the sample. It is vital to understand the structure of possible defects in the crystal, because they can influence the structure determination. All conventional methods to characterize defects require a modelling through simulated data. No direct methods exist to image the core of defects in crystals. Here a new method is proposed, which will enable to visualize the individual scatterers around and at defects in crystals. The method is based on coherent X-ray scattering. X-rays are perfectly suited since they can penetrate thick samples and buried structures can be investigated Recent developments increased the coherent flux of X-Ray sources such as synchrotrons by orders of magnitude. As a result, the use of the coherent properties of X-rays is emerging as a new aspect of X-ray science. New upcoming and operating X-ray laser sources will accelerate this trend. One new method which has the capacity to recover structural information from the coherently scattered photons is Coherent X-ray Diffraction Imaging (CXDI). The main focus of this thesis is the investigation of the structure and the dynamics of colloidal crystals. Colloidal crystals can be used as a model for atomic crystals in order to understand the growth and defect structure. Despite the large interest in these structures, many details are still unknown.Therefore, it is vital to develop new approaches to measure the core of defects in colloidal crystals. After an introduction into the basics of the field of coherent X-ray scattering, this thesis introduces a novel method, Small Angle Bragg Coherent Diffractive Imaging, (SAB-CDI). This new measurement technique which besides the relevance to colloidal crystals can be applied to a large variety of nano structured materials. To verify the experimental possibilities the

  19. Preparation and structure characteristics of nano-Bi2O3 powders with mixed crystal structure

    Institute of Scientific and Technical Information of China (English)

    LI Wei

    2005-01-01

    The nano-Bi2 O3 powders were prepared by a chemical precipitation method with Bi(NO3)3, H NO3 and NaOH as reactants. The structural characteristics and morphology of nano-Bi2O3 powders were investigated by X-ray diffraction and transmission electron microscopy, respectively. The results show that under the optimum condition that 300 g/L Bi(NO3)3 reacts at 90 ℃ for 2 h, the Bi2O3 powders with 60 nm on the average and 99.5% in purity are obtained. The prepared nano-Bi2 O3 powders contain a mixed crystal structure of monoclinic and triclinic in stead of traditional structure of monoclinic α-Bi2 O3. And the mixed crystal structure is stable in air. The reason for the appearance of the mixed crystal structure may be that the ionic radius ratio of Bi3+ to O2- changes easily during the formation of nano-Bi2 O3 particles by a chemical precipitation method.

  20. Hierarchical periodic micro/nano-structures on nitinol and their influence on oriented endothelialization and anti-thrombosis.

    Science.gov (United States)

    Nozaki, Kosuke; Shinonaga, Togo; Ebe, Noriko; Horiuchi, Naohiro; Nakamura, Miho; Tsutsumi, Yusuke; Hanawa, Takao; Tsukamoto, Masahiro; Yamashita, Kimihiro; Nagai, Akiko

    2015-12-01

    The applications of hierarchical micro/nano-structures, which possess properties of two-scale roughness, have been studied in various fields. In this study, hierarchical periodic micro/nano-structures were fabricated on nitinol, an equiatomic Ni-Ti alloy, using a femtosecond laser for the surface modification of intravascular stents. By controlling the laser fluence, two types of surfaces were developed: periodic nano- and micro/nano-structures. Evaluation of water contact angles indicated that the nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. Endothelial cells aligned along the nano-structures on both surfaces, whereas platelets failed to adhere to the micro/nano-surface. Decorrelation between the responses of the two cell types and the results of water contact angle analysis were a result of the pinning effect. This is the first study to show the applicability of hierarchical periodic micro/nano-structures for surface modification of nitinol.

  1. Nano-Composites: Relationships Between Nano-Structure and Mechanical Properties: Phase II

    Science.gov (United States)

    2006-01-01

    a standard diglycidyl ether of bis-phenol A ( DGEBA ) with an epoxy equivalent weight (EEW) of 185 g/mol, ‘Bakelite EPR 164’ supplied by Bakelite AG...Duisberg, Germany. The nano-particles of silica (SiO2) were obtained at a concentration at 40wt.% in this DGEBA epoxy resin: ‘Nanopox F400’ from...the simple DGEBA epoxy with given amounts of the nano-SiO2 epoxy and CTBN- epoxy adduct, to give the required levels of added nano-SiO2 and CTBN

  2. Plasmonic enhancement of UV emission from ZnO thin films induced by Al nano-concave arrays

    Energy Technology Data Exchange (ETDEWEB)

    Norek, Małgorzata, E-mail: mnorek@wat.edu.pl [Department of Advanced Materials and Technologies, Faculty of Advanced Technologies and Chemistry, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Łuka, Grzegorz [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw (Poland); Włodarski, Maksymilian [Institute of Optoelectronics, Military University of Technology, Str. Kaliskiego 2, 00-908 Warszawa (Poland)

    2016-10-30

    Highlights: • Al nano-concave arrays with different interpore distance (D{sub c}) were prepared. • PL of ZnO thin films deposited directly on the Al nano-concaves were studied. • The effect of 10 nm Al{sub 2}O{sub 3} spacer on PL emission from ZnO thin films was analyzed. • Plasmonic enhancement of the PL emission was dependent on the D{sub c} and the spacer. • The highest 9-fold enhancement was obtained for the Al/ZnO sample with D{sub c} ∼333 nm. - Abstract: Surface plasmons (SPs) supported by Al nano-concave arrays with increasing interpore distance (D{sub c}) were used to enhance the ultraviolet light emission from ZnO thin films. Two sets of samples were prepared: in the first set the thin ZnO films were deposited directly on Al nanoconcaves (the Al/ZnO samples) and in the second set a 10 nm − Al{sub 2}O{sub 3} spacer was placed between the textured Al and the ZnO films (the Al/Al{sub 2}O{sub 3}-ALD/ZnO samples). In the Al/ZnO samples the enhancement was limited by a nonradiative energy dissipation due to the Ohmic loss in the Al metal. However, for the ZnO layer deposited directly on Al nanopits synthesized at 150 V (D{sub c} = 333 ± 18 nm), the largest 9-fold enhancement was obtained by achieving the best energy fit between the near band-edge (NBE) emission from ZnO and the λ{sub (0,1)} SPP resonance mode. In the Al/Al{sub 2}O{sub 3}-ALD/ZnO samples the amplification of the UV emission was smaller than in the Al/ZnO samples due to a big energy mismatch between the NBE emission and the λ{sub (0,1)} plasmonic mode. The results obtained in this work indicate that better tuning of the NBE − λ{sub (0,1)} SPP resonance mode coupling is possible through a proper modification of geometrical parameters in the Al/Al{sub 2}O{sub 3}-ALD/ZnO system such as Al nano-concave spacing and the thickness of the corresponding layer. This approach will reduce the negative influence of the non-radiative plasmonic modes and most likely will lead to further

  3. Nano-sized magnetic instabilities in Fe/NiO/Fe(001) epitaxial thin films

    Energy Technology Data Exchange (ETDEWEB)

    Brambilla, A. [Dipartimento di Fisica-Politecnico di Milano, P.za Leonardo da Vinci 32, 20133 Milan (Italy)]. E-mail: alberto.brambilla@polimi.it; Biagioni, P. [Dipartimento di Fisica-Politecnico di Milano, P.za Leonardo da Vinci 32, 20133 Milan (Italy); Rougemaille, N. [National Center for Electron Microscopy, Lawrence Berkeley National Lab, Berkeley, CA 94720 (United States); Schmid, A.K. [National Center for Electron Microscopy, Lawrence Berkeley National Lab, Berkeley, CA 94720 (United States); Lanzara, A. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720 (United States); Duo, L. [Dipartimento di Fisica-Politecnico di Milano, P.za Leonardo da Vinci 32, 20133 Milan (Italy); Ciccacci, F. [Dipartimento di Fisica-Politecnico di Milano, P.za Leonardo da Vinci 32, 20133 Milan (Italy); Finazzi, M. [Dipartimento di Fisica-Politecnico di Milano, P.za Leonardo da Vinci 32, 20133 Milan (Italy)

    2006-10-25

    We report on a magnetic imaging study of the Fe/NiO/Fe(001) trilayer structure, by means of X-ray photoemission electron microscopy (XPEEM) and spin-polarised low-energy electron microscopy (SPLEEM). Two different magnetic couplings between the Fe layers are observed depending on the NiO thickness being greater or smaller than a critical value. Very small magnetic domains and domain walls are observed in the top Fe layer. They are dramatically smaller than those observed in the Fe substrate, and have a convoluted topology. Furthermore they seem to be unstable with respect to an applied magnetic field for any NiO thickness except that corresponding to the transition between the different coupling regimes. The phenomenology of such magnetic nano-structures and the dependence of the magnetic behaviour of the layered structure on the NiO spacer thickness are discussed on the basis of the experimental results and of state-of-the-art theoretical models.

  4. Preparation and properties on hollow nano-structured smoke material

    Science.gov (United States)

    Liu, Xiang-cui; Dai, Meng-yan; Fang, Guo-feng; Shi, Wei-dong; Cheng, Xiang; Liu, Hai-feng; Zhang, Tong

    2013-09-01

    In recent years, the weapon systems of laser guidance and infrared (IR) imaging guidance have been widely used in modern warfare because of their high precision and strong anti-interference. Notwithstanding, military smoke, as a rapid and effective passive jamming means, can effectively counteract the attack of enemy precision-guided weapons by scattering and absorbability. Conventional smoke has good attenuation capability only to visible light (0.4-0.76 μm), but hardly any effect to other electromagnetic wave band. The weapon systems of laser guidance and IR imaging guidance usually work in broad band, including near IR (1-3 μm), middle IR (3-5 μm), far IR (8-14 μm), and so on. Accordingly, exploiting and using new efficient obscurant materials, which is one of the important factors that develop smoke technology, have become a focus and attracted more interests around the world. Then nano-structured materials that are developing very quickly have turned into our new choice. Hollow nano-structured materials (HNSM) have many special properties because of their nano-size wall-thickness and sub-micron grain-size. After a lot of HNSM were synthesized in this paper, their physical and chemical properties, including grain size, phase composition, microstructure, optical properties and resistivity were tested and analysed. Then the experimental results of the optical properties showed that HNSM exhibit excellent wave-absorbing ability in ultraviolet, visible and infrared regions. On the basis of the physicochemmical properties, HNSM are firstly applied in smoke technology field. And the obscuration performance of HNSM smoke was tested in smoke chamber. The testing waveband included 1.06μm and 10.6μm laser, 3-5μm and 8-14μm IR radiation. Then the main parameters were obtained, including the attenuation rate, the transmission rate, the mass extinction coefficient, the efficiency obscuring time, and the sedimentation rate, etc. The main parameters of HNSM smoke were

  5. Nano-spectroscopic imaging of intermolecular structure, coupling and dynamics

    CERN Document Server

    Pollard, Benjamin; Hinrichs, Karsten; Raschke, Markus B

    2013-01-01

    Molecular self-assembly, the function of biomembranes, and the performance of organic solar cells rely on molecular interactions on the nanoscale. The understanding and design of such intrinsic or engineered heterogeneous functional soft matter has long been impeded by a lack of spectroscopic tools with sufficient nanometer spatial resolution, attomolar sensitivity, and intermolecular spectroscopic specificity. We implement vibrational scattering-scanning near-field optical microscopy ($s$-SNOM) in a multi-spectral modality with unprecedented spectral precision to investigate the structure-function relationship in nano-phase separated block-copolymers. We use a vibrational resonance as a sensitive reporter of the local chemical environment and resolve, with few nanometer spatial resolution and 0.2 cm$^{-1}$ spectral precision, spectral Stark shifts and line broadening correlated with molecular-scale morphologies. By creating images of solvatochromic vibrational shifts we discriminate local variations in elect...

  6. Hierarchical periodic micro/nano-structures on nitinol and their influence on oriented endothelialization and anti-thrombosis

    Energy Technology Data Exchange (ETDEWEB)

    Nozaki, Kosuke [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Shinonaga, Togo [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Ebe, Noriko; Horiuchi, Naohiro; Nakamura, Miho; Tsutsumi, Yusuke; Hanawa, Takao [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Tsukamoto, Masahiro [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Yamashita, Kimihiro [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Nagai, Akiko, E-mail: nag-bcr@tmd.ac.jp [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan)

    2015-12-01

    The applications of hierarchical micro/nano-structures, which possess properties of two-scale roughness, have been studied in various fields. In this study, hierarchical periodic micro/nano-structures were fabricated on nitinol, an equiatomic Ni–Ti alloy, using a femtosecond laser for the surface modification of intravascular stents. By controlling the laser fluence, two types of surfaces were developed: periodic nano- and micro/nano-structures. Evaluation of water contact angles indicated that the nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. Endothelial cells aligned along the nano-structures on both surfaces, whereas platelets failed to adhere to the micro/nano-surface. Decorrelation between the responses of the two cell types and the results of water contact angle analysis were a result of the pinning effect. This is the first study to show the applicability of hierarchical periodic micro/nano-structures for surface modification of nitinol. - Highlights: • Hierarchical micro/nano-structures were created on nitinol using a femtosecond laser. • The nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. • Endothelial cells aligned along the nano-structures • Platelets failed to adhere to the micro/nano-surface.

  7. Nano-Floating Gate Memory Devices Composed of ZnO Thin-Film Transistors on Flexible Plastics

    Directory of Open Access Journals (Sweden)

    Park Byoungjun

    2011-01-01

    Full Text Available Abstract Nano-floating gate memory devices were fabricated on a flexible plastic substrate by a low-temperature fabrication process. The memory characteristics of ZnO-based thin-film transistors with Al nanoparticles embedded in the gate oxides were investigated in this study. Their electron mobility was found to be 0.18 cm2/V·s and their on/off ratio was in the range of 104–105. The threshold voltages of the programmed and erased states were negligibly changed up to 103 cycles. The flexibility, memory properties, and low-temperature fabrication of the nano-floating gate memory devices described herein suggest that they have potential applications for future flexible integrated electronics.

  8. Hybrid nano-structure for enhanced energy storage devices

    Science.gov (United States)

    Shuvo, Mohammad Arif Ishtiaque

    The goal of this research is to develop electrode materials using various nano-structure hybrids for improved energy storage devices. Enhancing the performance of energy storage device has been gaining tremendous attention since it holds the key solution to advance renewable energy usage thus reduce the consumption of fossil fuels. The application of energy storage devices such as super-capacitor and Li-ion-battery has seen significant growth; however, it is still limited mainly by charge/discharge rate and energy density. One of the solutions is to use nano-structure materials, which offer higher power at high energy density and improved stability during the charge discharge cycling of ions in and out of the storage electrode material. In this research, carbon-based materials (e.g. porous carbon, graphene) in conjunction with metal oxides such as CeO2 nanoparticles/TiO2 nanowires are synthesized utilizing low temperature hydrothermal method for the fabrication of advanced electrode materials. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transformation Infrared Spectroscopy (FTIR) were used for materials characterization. Poentio-galvanostat, battery analyzer, and Electrochemical Impedance Spectroscopy (EIS) were used for evaluating the electrochemical performance. The testing results have shown that a maximum 500% higher specific capacitance could be obtained using porous carbon/CeO2 instead of porous carbon for super-capacitor application and microwave exfoliated graphene oxide/TiO2 nanowire hybrid provides up to 80% increment of specific capacity compared to porous carbon anode for Li-ion-battery application.

  9. Structural analysis of bioinspired nano materials with synchrotron far IR spectroscopy.

    Science.gov (United States)

    Seoudi, Rania S; Dowd, Annette; Smith, Brian J; Mechler, Adam

    2016-04-28

    Bioinspired fibres and hierarchical nano-materials are based on the self-assembly of organic building blocks such as polypeptides. Confirming the core structure of such materials is often challenging as they lack the long-range order required by crystallographic methods. Far-IR spectroscopy characterizes the vibrational modes of large molecular units. These vibrational modes are very sensitive to angle strain and second order interactions such as hydrogen bonding. As such, far-IR spectra hold information about the secondary structure and interactions of large biomolecules. Here we analyze the far-IR vibrational spectra of fibrous nano-materials based on three isomeric unnatural tripeptides, Ac-β(3)Leu-β(3)Ile-β(3)Ala, Ac-β(3)Ile-β(3)Ala-β(3)Leu, and Ac-β(3)Ala-β(3)Leu-β(3)Ile. These peptides have well described self-assembly characteristics, forming one-dimensional nanorods that impose tight conformational constraints on the constituent molecules. The synchrotron far-IR spectroscopic results were interpreted by using density functional theory (DFT) modelling based vibrational analysis. The sensitivity of the spectra to peptide conformation was assessed by comparing the experimental spectra with DFT predictions. In high dielectric implicit solvent, intramolecular hydrogen-bonding is inhibited and thus the energy minimized peptide structure remains close to the 14-helix folding characteristic of substituted β(3)-peptides, giving good agreement between the experimental and predicted vibration spectra. In contrast, energy minimization in vacuum alters the peptide conformation leading to intramolecular hydrogen bonds, and hence the predicted vibration spectra do not agree with the experimental data. Therefore, our results demonstrate the ability of far-IR spectroscopy to identify correct structural predictions and thus open the way for using far-IR spectroscopy for the characterization and structural analysis of bioinspired nano-materials and potentially their

  10. Structural and optical properties of SnO{sub 2} nano films by spin-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Uysal, Bengü Özuğur, E-mail: bozugur@khas.edu.tr [Department of Energy Systems Engineering, Faculty of Engineering and Natural Sciences, Kadir Has University, Fatih, Istanbul, 34083 (Turkey); Arıer, Ümit Özlem Akkaya [Department of Physics, Faculty of Science and Letters, Mimar Sinan Fine Arts University, Beşiktaş, Istanbul 34349 (Turkey)

    2015-09-30

    Highlights: • SnO{sub 2} nano films were deposited on glass substrates by spin-coating method. • The structural and optical properties of SnO{sub 2} nano films were characterized. • The properties of SnO{sub 2} nano films were controlled by changing the SnCl{sub 2}:water ratio. • The activation energy and the band gap energy values of the films were determined. - Abstract: In this work, tin oxide (SnO{sub 2}) nano films were deposited on glass substrates with different water content using the sol–gel spin-coating method. SnO{sub 2} is a wide band gap semiconductor and it belongs to the class of transparent conductive oxides (TCO). The influence of the water content and the heat treatment temperature on the structural and optical properties of the thin films is characterized by X-ray diffractometer (XRD), scanning electron microscope, atomic force microscope, ultraviolet–visible spectrophotometer, and spectrophotometer. Crystallite size of nano SnO{sub 2} films was controlled by SnCl{sub 2}:water ratios. The most significant characteristic of nano materials is the increase in surface area as particle size decreases. XRD studies showed that the formation of tetragonal rutil phase was initiated at an annealing temperature close to 450 °C. The activation energy of nano SnO{sub 2} films for particle growth was calculated. The film has an activation energy of 42.8 kJ/mol, and the optical band gap of 3.02-3.35 eV is proportional to the SnCl{sub 2}:water ratio. The quantum size effect of nano particles was confirmed by the band gap energy shift, using ultraviolet–visible spectroscopy (UV–vis). SnO{sub 2} films have been considered as one of the most promising functional materials due to their wide direct band-gap, and excellent electrical and optical properties. Those properties of SnO{sub 2} films allow them to be used in electronic and optoelectronic devices like gas sensors, solar cells and lithium batteries etc.

  11. Investigations on structural thinning in deformation machining stretching mode

    Science.gov (United States)

    Singh, Arshpreet; Nirala, Harish Kumar; Agrawal, Anupam

    2016-10-01

    Deformation machining is a combination of thin structure machining and single point incremental forming/bending. This process enables the creation of monolithic, complex structures and geometries, which are difficult or sometimes impossible to manufacture employing conventional manufacturing techniques. Section thinning of the formed structure is a measure of process formability and influences the strength and stiffness of the formed component. In this study, experimental and finite element investigations on structural thinning in Deformation machining stretching mode have been performed. Structural thinning was found out to be highly non uniform along the forming depth at varying forming angles. A compensation strategy in thin structure machining has been proposed for uniform section thickness in incremental forming.

  12. Platinum and palladium nano-structured catalysts for polymer electrolyte fuel cells and direct methanol fuel cells.

    Science.gov (United States)

    Long, Nguyen Viet; Thi, Cao Minh; Yong, Yang; Nogami, Masayuki; Ohtaki, Michitaka

    2013-07-01

    In this review, we present the synthesis and characterization of Pt, Pd, Pt based bimetallic and multi-metallic nanoparticles with mixture, alloy and core-shell structure for nano-catalysis, energy conversion, and fuel cells. Here, Pt and Pd nanoparticles with modified nanostructures can be controllably synthesized via chemistry and physics for their uses as electro-catalysts. The cheap base metal catalysts can be studied in the relationship of crystal structure, size, morphology, shape, and composition for new catalysts with low cost. Thus, Pt based alloy and core-shell catalysts can be prepared with the thin Pt and Pt-Pd shell, which are proposed in low and high temperature proton exchange membrane fuel cells (PEMFCs), and direct methanol fuel cells (DMFCs). We also present the survey of the preparation of Pt and Pd based catalysts for the better catalytic activity, high durability, and stability. The structural transformations, quantum-size effects, and characterization of Pt and Pd based catalysts in the size ranges of 30 nm (1-30 nm) are presented in electro-catalysis. In the size range of 10 nm (1-10 nm), the pure Pt catalyst shows very large surface area for electro-catalysis. To achieve homogeneous size distribution, the shaped synthesis of the polyhedral Pt nanoparticles is presented. The new concept of shaping specific shapes and morphologies in the entire nano-scale from nano to micro, such as polyhedral, cube, octahedra, tetrahedra, bar, rod, and others of the nanoparticles is proposed, especially for noble and cheap metals. The uniform Pt based nanosystems of surface structure, internal structure, shape, and morphology in the nanosized ranges are very crucial to next fuel cells. Finally, the modifications of Pt and Pd based catalysts of alloy, core-shell, and mixture structures lead to find high catalytic activity, durability, and stability for nano-catalysis, energy conversion, fuel cells, especially the next large-scale commercialization of next

  13. Exchange bias and anisotropy analysis of nano-composite Co{sub 84}Zr{sub 16}N thin films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jitendra, E-mail: jitendra@ceeri.ernet.in [CSIR-Central Electronics Engineering Research Institute, Pilani, Rajasthan 333031 (India); Academy of Scientific and Innovative Research, Chennai 600113 (India); Taube, William Ringal [CSIR-Central Electronics Engineering Research Institute, Pilani, Rajasthan 333031 (India); Academy of Scientific and Innovative Research, Chennai 600113 (India); Ansari, Akhtar Saleem [Department of Applied Physics, Aligarh Muslim University, Aligarh 202002 (India); Gupta, Sanjeev Kumar [Academy of Scientific and Innovative Research, Chennai 600113 (India); Kulriya, Pawan Kumar [Inter-University Accelerator Centre, New Delhi 110067 (India); Akhtar, Jamil [CSIR-Central Electronics Engineering Research Institute, Pilani, Rajasthan 333031 (India); Academy of Scientific and Innovative Research, Chennai 600113 (India)

    2015-03-15

    Nano-composite Co{sub 84}Zr{sub 16}N (CZN) films were prepared by reactive co-sputter deposition. As-deposited CZN films have not shown any exchange bias effect. But annealed (390 K) and field cooled samples have shown exchange bias phenomena. The observed exchange bias is attributed to inter-cluster exchange coupling between ferromagnetic and antiferromagnetic nano-composite phase. High resolution transmission electron microscope study reveals that, the CZN films are composed of ordered and crystalline ferromagnetic Cobalt nano-clusters embedded in an antiferromagnetic matrix. X-ray diffraction confirms the poly-crystalline growth of the CZN films with a preferred fcc (622) phase formation. In-plane anisotropy of the exchange biased films was investigated by rotational magnetization curve, and the analysis shows that the magnetization reversal behaves according to the coherent rotation of the magnetic moment vector. Effectively, exchange bias effect in such single layer films could be attributed to co-existing antiferromagnetic and ferromagnetic phase within the single layer. Such single layer nano-composite films can be a possible alternative to the bilayer combination of antiferromagnetic/ferromagnetic exchange biased films and are ideally suited for spintronics and tunnel junction applications. - Highlights: • Exchange bias effect observed in 390 K annealed and field cooled single layer nanocomposite Co{sub 84}Zr{sub 16}N (CZN) thin films. • CZN films are composed of ordered and crystalline ferromagnetic Cobalt nano-clusters embedded in antiferromagnetic matrix. • Uniaxial magnetic anisotropy investigated by rotational magnetization curve, and magnetization reversal behaves according to coherent rotation of magnetic moment vector. • Co-existing FM and AF phases in composite matrix are lead to extraordinary EB behavior.

  14. Development of multifunctional nano/ultrafiltration membrane based on a chitosan thin film on alginate electrospun nanofibres

    CSIR Research Space (South Africa)

    Mokhena, Teboho C

    2017-07-01

    Full Text Available of Cleaner Production Development of multifunctional nano/ultrafiltration membrane based on a chitosan thin film on alginate electrospun nanofibers Teboho Clement Mokhena a, b, Adriaan Stephanus Luyt c, * a CSIR Materials Science and Manufacturing... stream_source_info Mokhena_2017_ABSTRACT.pdf.txt stream_content_type text/plain stream_size 1910 Content-Encoding ISO-8859-1 stream_name Mokhena_2017_ABSTRACT.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Journal...

  15. Interfacial engineering of two-dimensional nano-structured materials by atomic layer deposition

    Science.gov (United States)

    Zhuiykov, Serge; Kawaguchi, Toshikazu; Hai, Zhenyin; Karbalaei Akbari, Mohammad; Heynderickx, Philippe M.

    2017-01-01

    Atomic Layer Deposition (ALD) is an enabling technology which provides coating and material features with significant advantages compared to other existing techniques for depositing precise nanometer-thin two-dimensional (2D) nanostructures. It is a cyclic process which relies on sequential self-terminating reactions between gas phase precursor molecules and a solid surface. ALD is especially advantageous when the film quality or thickness is critical, offering ultra-high aspect ratios. ALD provides digital thickness control to the atomic level by depositing film one atomic layer at a time, as well as pinhole-free films even over a very large and complex areas. Digital control extends to sandwiches, hetero-structures, nano-laminates, metal oxides, graded index layers and doping, and it is perfect for conformal coating and challenging 2D electrodes for various functional devices. The technique's capabilities are presented on the example of ALD-developed ultra-thin 2D tungsten oxide (WO3) over the large area of standard 4" Si substrates. The discussed advantages of ALD enable and endorse the employment of this technique for the development of hetero-nanostructure 2D semiconductors with unique properties.

  16. Structure-property relationships of multiferroic materials: A nano perspective

    Science.gov (United States)

    Bai, Feiming

    The integration of sensors, actuators, and control systems is an ongoing process in a wide range of applications covering automotive, medical, military, and consumer electronic markets. Four major families of ceramic and metallic actuators are under development: piezoelectrics, electrostrictors, magnetostrictors, and shape-memory alloys. All of these materials undergo at least two phase transformations with coupled thermodynamic order parameters. These transformations lead to complex domain wall behaviors, which are driven by electric fields (ferroelectrics), magnetic fields (ferromagnetics), or mechanical stress (ferroelastics) as they transform from nonferroic to ferroic states, contributing to the sensing and actuating capabilities. This research focuses on two multiferroic crystals, Pb(Mg1/3Nb 2/3)O3-PbTiO3 and Fe-Ga, which are characterized by the co-existence and coupling of ferroelectric polarization and ferroelastic strain, or ferro-magnetization and ferroelastic strain. These materials break the conventional boundary between piezoelectric and electrostrictors, or magnetostrictors and shape-memory alloys. Upon applying field or in a poled condition, they yield not only a large strain but also a large strain over field ratio, which is desired and much benefits for advanced actuator and sensor applications. In this thesis, particular attention has been given to understand the structure-property relationships of these two types of materials from atomic to the nano/macro scale. X-ray and neutron diffraction were used to obtain the lattice structure and phase transformation characteristics. Piezoresponse and magnetic force microscopy were performed to establish the dependence of domain configurations on composition, thermal history and applied fields. It has been found that polar nano regions (PNRs) make significant contributions to the enhanced electromechanical properties of PMN-x%PT crystals via assisting intermediate phase transformation. With increasing PT

  17. A nano-grid structure made of perovskite SrTiO3 nanowires for efficient electron transport layers in inverted polymer solar cells

    Science.gov (United States)

    Kim, Jeong Won; Suh, Yo-Han; Lee, Chang-Lyoul; Kim, Yong Seok; Kim, Won Bae

    2015-02-01

    A nano-grid structure of perovskite SrTiO3 NWs is developed for a novel electron transport layer in inverted polymer solar cells. Due to the excellent charge transporting properties of the SrTiO3 nano-grid structure, the device employing this nanostructure showed ~32% enhanced photovoltaic performance, compared to the solar cell using a TiO2 thin film.A nano-grid structure of perovskite SrTiO3 NWs is developed for a novel electron transport layer in inverted polymer solar cells. Due to the excellent charge transporting properties of the SrTiO3 nano-grid structure, the device employing this nanostructure showed ~32% enhanced photovoltaic performance, compared to the solar cell using a TiO2 thin film. Electronic supplementary information (ESI) available: Experimental details, HR-TEM images with EDX atomic ratio analysis, FE-SEM images, transmittance spectra and light absorbance spectra. See DOI: 10.1039/c4nr06720g

  18. Multi-resonant silver nano-disk patterned thin film hydrogenated amorphous silicon solar cells for Staebler-Wronski effect compensation

    CERN Document Server

    Vora, Ankit; Pearce, Joshua M; Bergstrom, Paul L; Güney, Durdu Ö

    2014-01-01

    We study polarization independent improved light trapping in commercial thin film hydrogenated amorphous silicon (a-Si:H) solar photovoltaic cells using a three-dimensional silver array of multi-resonant nano-disk structures embedded in a silicon nitride anti-reflection coating (ARC) to enhance optical absorption in the intrinsic layer (i-a-Si:H) for the visible spectrum for any polarization angle. Predicted total optical enhancement (OE) in absorption in the i-a-Si:H for AM-1.5 solar spectrum is 18.51% as compared to the reference, and producing a 19.65% improvement in short-circuit current density (JSC) over 11.7 mA/cm2 for a reference cell. The JSC in the nano-disk patterned solar cell (NDPSC) was found to be higher than the commercial reference structure for any incident angle. The NDPSC has a multi-resonant optical response for the visible spectrum and the associated mechanism for OE in i-a-Si:H layer is excitation of Fabry-Perot resonance facilitated by surface plasmon resonances. The detrimental Staebl...

  19. Encapsulation of pancreatic islets within nano-thin functional polyethylene glycol coatings for enhanced insulin secretion.

    Science.gov (United States)

    Kizilel, Seda; Scavone, Andrew; Liu, Xiang; Nothias, Jean-Manuel; Ostrega, Diane; Witkowski, Piotr; Millis, Michael

    2010-07-01

    Covalent attachment of polymers to cells and tissues could be used to solve a variety of problems associated with cellular therapies. Insulin-dependent diabetes mellitus is a disease resulting from the autoimmune destruction of the beta cells of the islets of Langerhans in the pancreas. Transplantation of islets into diabetic patients is an attractive form of treatment, provided that the islets could be protected from the host's immune system to prevent graft rejection, and smaller numbers of islets transplanted in smaller volumes could be sufficient to reverse diabetes. Therefore, a need exists to develop islet encapsulation strategies that minimize transplant volume. In this study, we demonstrate the formation of nano-thin, poly(ethylene glycol) (PEG)-rich functional conformal coatings on individual islets via layer-by-layer assembly technique. The surface of the islets is modified with biotin-PEG-N-hydroxysuccinimide (NHS), and the islets are further covered by streptavidin (SA) and biotin-PEG-peptide conjugates using the layer-by-layer method. An insulinotropic ligand, glucagon-like peptide-1 (GLP-1), is conjugated to biotin-PEG-NHS. The insulinotropic effect of GLP-1 is investigated through layer-by-layer encapsulation of islets using the biotin-PEG-GLP-1 conjugate. The effect of islet surface modification using the biotin-PEG-GLP-1 conjugate on insulin secretion in response to glucose challenge is compared via static incubation and dynamic perifusion assays. The results show that islets coated with the functional PEG conjugate are capable of secreting more insulin in response to high glucose levels compared to control islets. Finally, the presence of SA is confirmed by indirect fluorescent staining with SA-Cy3, and the presence of PEG-peptide on the surface of the islets after treatment with biotin-PEG-GLP-1 is confirmed by indirect fluorescent staining with biotin-PEG-fluorescein isothiocyanate (FITC) and separately with an anti-GLP-1 antibody. This work

  20. Molecular dynamics simulation of nano-indentation on Ti-V multilayered thin films

    Science.gov (United States)

    Feng, Chao; Peng, Xianghe; Fu, Tao; Zhao, Yinbo; Huang, Cheng; Wang, Zhongchang

    2017-03-01

    We developed a second nearest-neighbor modified embedded-atom method potential for binary Ti-V system. The potential parameters were identified by fitting the lattice parameter, cohesive energy and elastic constants of CsCl-type TiV, and further validated by reproducing the fundamental physical and mechanical properties of Ti-V systems with other crystal structures. In addition, we also performed molecular dynamics simulations of nano-indentation processes of pure Ti film, pure V film, and two kinds of four-layer Ti-V films, V-Ti-V-Ti and Ti-V-Ti-V. We found that the indentation force-depth curve for the pure V film turns flat at an indentation depth of 2.8 nm, where a prismatic loop was observed. Such prismatic loop is not found in the V/Ti/V/Ti multilayer because the thickness of each layer is insufficient for the formation of such prismatic loops, which accounts for the increase of stress in the multilayer.

  1. Chemically synthesized PbS Nano particulate thin films for a rapid NO2 gas sensor

    Directory of Open Access Journals (Sweden)

    Burungale Vishal V.

    2016-03-01

    Full Text Available Rapid NO2 gas sensor has been developed based on PbS nanoparticulate thin films synthesized by Successive Ionic Layer Adsorption and Reaction (SILAR method at different precursor concentrations. The structural and morphological properties were investigated by means of X-ray diffraction and field emission scanning electron microscope. NO2 gas sensing properties of PbS thin films deposited at different concentrations were tested. PbS film with 0.25 M precursor concentration showed the highest sensitivity. In order to optimize the operating temperature, the sensitivity of the sensor to 50 ppm NO2 gas was measured at different operating temperatures, from 50 to 200 °C. The gas sensitivity increased with an increase in operating temperature and achieved the maximum value at 150 °C, followed by a decrease in sensitivity with further increase of the operating temperature. The sensitivity was about 35 % for 50 ppm NO2 at 150 °C with rapid response time of 6 s. T90 and T10 recovery time was 97 s at this gas concentration.

  2. Graphene nano-devices and nano-composites for structural, thermal and sensing applications

    Science.gov (United States)

    Yavari, Fazel

    In this dissertation we have developed graphene-based nano-devices for applications in integrated circuits and gas sensors; as well as graphene-based nano-composites for applications in structures and thermal management. First, we have studied the bandgap of graphene for semiconductor applications. Graphene as a zero-bandgap material cannot be used in the semiconductor industry unless an effective method is developed to open the bandgap in this material. We have demonstrated that a bandgap of 0.206 eV can be opened in graphene by adsorption of water vapor molecules on its surface. Water molecules break the molecular symmetries of graphene resulting in a significant bandgap opening. We also illustrate that the lack of bandgap in graphene can be used to our advantage by making sensors that are able to detect low concentrations of gas molecules mixed in air. We have shown that 1-2 layers of graphene synthesized by chemical vapor deposition enables detection of trace amounts of NO 2 and NH3 in air at room temperature and atmospheric pressure. The gas species are detected by monitoring changes in electrical resistance of the graphene film due to gas adsorption. The sensor response time is inversely proportional to the gas concentration. Heating the film expels chemisorbed molecules from the graphene surface enabling reversible operation. The detection limits of ~100 parts-per-billion (ppb) for NO2 and ~500 ppb for NH3 obtained using this device are markedly superior to commercially available NO2 and NH3 detectors. This sensor is fabricated using individual graphene sheets that are exquisitely sensitive to the chemical environment. However, the fabrication and operation of devices that use individual nanostructures for sensing is complex, expensive and suffers from poor reliability due to contamination and large variability from sample-to-sample. To overcome these problems we have developed a gas sensor based on a porous 3D network of graphene sheets called graphene foam

  3. Synthesis and micro-structural study of one-dimensional nano-materials

    Institute of Scientific and Technical Information of China (English)

    周光文; 张泽; 俞大鹏

    1999-01-01

    Silicon nano-wires (SiNWs) and boron nitride nano-tubules (BN-NTs) were successfully synthesized by excimer laser ablation at high temperature. These one-dimensional nano-materials synthesized by this method have a very high yield, a uniform diameter distribution, and a high purity. Micro-structures of these nano-materials were investigated by transmission electron microscopy (TEM). The SiNWs have a high density of structural defects of microtwin, stacking faults, and low-angle boundary, which ere closely related to the formation of SiNWs and the determination of morphology of the nano-wires. BN-NTs ere mainly single atomic-layered and the outer surface of tubules is clean without any attachment. The formation of single atomic-layered tubule is attributed to the catalyst effect which makes the axial rate of BN-NTs much higher than the radial growth.

  4. A nano-structured ZnO film as diagnostic X-ray sensor

    Energy Technology Data Exchange (ETDEWEB)

    Valenca, Claudia Patricia Varela; Liborio da Silveira, Matheus Augusto; Macedo, Marcelo Andrade; Pereira dos Santos, Luiz Antonio [CNEN/CRCN-NE Av. Prof. Luiz Freire, 1 Cidade Universitaria RECIFE-PE CEP 50740-540 (Brazil)

    2015-07-01

    Currently some international organizations such as WHO and IAEA have shown concerns about the quality of diagnostic services in clinics and hospitals that use ionizing radiation. In fact, the IAEA recommend that the characteristics of the X-ray beam must be adjusted to obtain the highest quality of the radiographic image with the minimum exposure to the patient. Several types of detectors may be used for monitoring X-ray beams, such as: ionization chamber, photodiode, phototransistor, among others. Recently nano-structured films made of various types of metal oxide materials have been used for various technological applications. Accordingly, the purpose of this paper is to present a sort of device based on a nano-structured zinc oxide (ZnO) to operate as a diagnostic X-ray sensor. By depositing a thin film on the glass substrate some ZnO semiconductor samples were built by sputtering techniques and then mounted in a BNC type connector to perform the electrical characterization. To test the device, we choose a standard X-Ray beam, the RQR9 radiation quality, which is normally used as the tool and condition for calibrating diagnostic X-Ray instruments in the energy range of computed tomography, in accordance with the stated requirements of IEC 61267. A 6430 sub-femto-ammeter, Keithley, was used as electrometer to perform the output readings and simultaneously bias the ZnO sensor. Analysis of the angular dependence and the dose rate were performed to evaluate how the device responds under the RQR9 radiation spectra. Although the results have shown that the ZnO film presents a certain angular dependence, if an angle of incidence of photons is selected, the device displays reproducibility as X-ray sensor and has the feature of radiation hardness unlike other types of semiconductor electronic devices typically used as an X-ray detector. (authors)

  5. Nano-structural characteristics of carbon nanotube-polymer composite films for high-amplitude optoacoustic generation

    Science.gov (United States)

    Baac, Hyoung Won; Ok, Jong G.; Lee, Taehwa; Jay Guo, L.

    2015-08-01

    We demonstrate nano-structural characteristics of carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite films that can be used as highly efficient and robust ultrasound transmitters for diagnostic and therapeutic applications. An inherent architecture of the nano-composite provides unique thermal, optical, and mechanical properties that are accommodated not just for efficient energy conversion but also for extraordinary robustness against pulsed laser ablation. First, we explain a thermoacoustic transfer mechanism within the nano-composite. CNT morphologies are examined to determine a suitable arrangement for heat transfer to the surrounding PDMS. Next, we introduce an approach to enhance optical extinction of the composite films, which uses shadowed deposition of a thin Au layer through an as-grown CNT network. Finally, the transmitter robustness is quantified in terms of laser-induced damage threshold. This reveals that the CNT-PDMS films can withstand an order-of-magnitude higher optical fluence (and extinction) than a Cr film used as a reference. Such robustness is crucial to increase the maximum-available optical energy for optoacoustic excitation and pressure generation. All of these structure-originated characteristics manifest the CNT-PDMS composite films as excellent optoacoustic transmitters for high-amplitude and high-frequency ultrasound generation.

  6. Nano-structural characteristics of carbon nanotube-polymer composite films for high-amplitude optoacoustic generation.

    Science.gov (United States)

    Baac, Hyoung Won; Ok, Jong G; Lee, Taehwa; Guo, L Jay

    2015-09-14

    We demonstrate nano-structural characteristics of carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite films that can be used as highly efficient and robust ultrasound transmitters for diagnostic and therapeutic applications. An inherent architecture of the nano-composite provides unique thermal, optical, and mechanical properties that are accommodated not just for efficient energy conversion but also for extraordinary robustness against pulsed laser ablation. First, we explain a thermoacoustic transfer mechanism within the nano-composite. CNT morphologies are examined to determine a suitable arrangement for heat transfer to the surrounding PDMS. Next, we introduce an approach to enhance optical extinction of the composite films, which uses shadowed deposition of a thin Au layer through an as-grown CNT network. Finally, the transmitter robustness is quantified in terms of laser-induced damage threshold. This reveals that the CNT-PDMS films can withstand an order-of-magnitude higher optical fluence (and extinction) than a Cr film used as a reference. Such robustness is crucial to increase the maximum-available optical energy for optoacoustic excitation and pressure generation. All of these structure-originated characteristics manifest the CNT-PDMS composite films as excellent optoacoustic transmitters for high-amplitude and high-frequency ultrasound generation.

  7. Photopatternable nano-composite (SU-8/ZnO) thin films for piezo-electric applications

    Science.gov (United States)

    Kandpal, Manoj; Sharan, Chandrashekhar; Poddar, Pankaj; Prashanthi, K.; Apte, Prakash R.; Ramgopal Rao, V.

    2012-09-01

    Photo-curable nanocomposite material was formulated by embedding ZnO nanoparticles into a SU-8 matrix and studied for its piezoelectric properties for low cost fabrication of self-powered nanodevices. The piezoelectric coefficient of ZnO nanoparticles was observed to be ranging between 15 and 23 pm/V, which is the highest reported. These experimental studies support the recent theoretical predictions where the piezoelectric coefficients in ZnO nanoparticles were found to be higher compared to the thin films because of the surface relaxation induced volume reductions in the nanometer scale. The photo-curable property of these polymer composite films is exploited to demonstrate fabrication of a micro-cantilever test structure.

  8. Structured SiCu thin films in LiB as anodes

    Energy Technology Data Exchange (ETDEWEB)

    Polat, Billur Deniz [Istanbul Technical Univ. (Turkey); Eryilmaz, Osman Levent [Argonne National Lab. (ANL), Argonne, IL (United States); Erck, Robert [Argonne National Lab. (ANL), Argonne, IL (United States); Keles, O. [Istanbul Technical Univ. (Turkey); Erdemir, A. [Argonne National Lab. (ANL), Argonne, IL (United States); Amine, Khalil [Argonne National Lab. (ANL), Argonne, IL (United States)

    2014-09-16

    Both helical and inclined columnar Si–10 at.% Cu structured thin films were deposited on Cu substrates using glancing angle deposition (GLAD) technique. In order to deposit Cu and Si two evaporation sources were used. Ion assistance was utilized in the first 5 min of the GLAD to enhance the adhesion and the density of the films. These films were characterized by thin film XRD, GDOES, SEM, and EDS. Electrochemical characterizations were made by testing the thin films as anodes in half-cells for 100 cycles. The results showed that the columnar SiCu thin film delivered 2200 mAh g-1, where the helical one exhibited 2600 mAh g-1, and, their initial coulombic efficiencies were found to be 38%–50% respectively. For the columnar and the helical thin film anodes, sustainable 520 and 800 mAh g-1 with 90% and 99% coulombic efficiencies were achieved for 100 cycles. These sustainable capacities showed the importance of the thin film structure having nano-sized crystals and amorphous particles. The higher surface area of the helices increases the capacity of the electrode because the contact area of the thin film anode with Li ions is increased, and the polarization which otherwise forms on the anode surface due to SEI formation is decreased. In addition, because of larger interspaces between the helices the ability of the anode to accommodate the volumetric changes is improved, which results in a higher coulombic efficiency and capacity retention during cycling test.

  9. Surface smoothing effect of an amorphous thin film deposited by atomic layer deposition on a surface with nano-sized roughness

    Directory of Open Access Journals (Sweden)

    W. S. Lau

    2014-02-01

    Full Text Available Previously, Lau (one of the authors pointed out that the deposition of an amorphous thin film by atomic layer deposition (ALD on a substrate with nano-sized roughness probably has a surface smoothing effect. In this letter, polycrystalline zinc oxide deposited by ALD onto a smooth substrate was used as a substrate with nano-sized roughness. Atomic force microscopy (AFM and cross-sectional transmission electron microscopy (XTEM were used to demonstrate that an amorphous aluminum oxide thin film deposited by ALD can reduce the surface roughness of a polycrystalline zinc oxide coated substrate.

  10. Microwave irradiation on carbon black: Studies on the transformation of particles into nano-balls, nano-sticks and nano-onion like structures

    Science.gov (United States)

    Asokan, Vijayshankar; Venkatachalapathy, Vishnukanthan; Rajavel, Krishnamoorthy; Madsen, Dorte Nørgaard

    2016-12-01

    The solid-state transformation behavior of carbon black (CB) nanoparticles after irradiated with microwave energy was studied with and without influence of a metal catalyst. The CB sample was exposed to microwave radiation at power of 900 W from the oven and collected after 15 min and after 30 min and 45 min of irradiation. The samples were characterized using X-ray diffraction measurements, Raman spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM) and thermogravimetric analysis. Characterization of the samples prepared without catalyst shows that microwave irradiation can transform CB nanoparticles into nano-balls and nano-stick like structures. While nanoballs of almost 300-500 nm diameter are visible in all the samples irrespective of microwave irradiation time, amorphous nano-stick like structure are present only in the sample collected after 30 min of microwave irradiation. CB irradiated together with a metal catalyst resulted in metal-encapsulated onion like structures with perfectly arranged graphene layers.

  11. Effect of Annealing on the Structural and Optical Properties of Nano Fiber ZnO Films Deposited by Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    M. R. Islam

    2011-11-01

    Full Text Available Nano fiber ZnO films have been deposited on to glass substrate at 200 °C by a simple spray pyrolysis technique under atmospheric pressure. The effect of annealing temperature on the structural and optical properties of the as grown films has been studied by Scanning Electron Microscopy (SEM attached with an EDX, powder X-ray diffraction and UV visible spectroscopy. The atomic weight % of Zinc and Oxygen were found to be 49.22 % and 49.62 % respectively. The SEM micrographs show nano fiber structure and uniform deposition on the substrate. Average grain size of ZnO thin film was found in the range of 21 to 27 nm. The lattice constant a and c of ZnO thin film are determined at different annealing temperatures and values are found slightly larger than those of JCPDS data and lower for the sample annealed at 600 °C. The lattice parameters a and c decrease with increasing temperature. It reveals that the samples are poly-crystalline and having with low densities. Band gap energy of ZnO was found in the range of 3.33 to 3.17 eV and decreases with the increase of the annealing temperature.

  12. Thin layer structure of dissipation rate of scalar turbulence

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Haibing; (周海兵); CUI; Guixiang; (崔桂香); XU; Chunxiao; (许春晓); ZHANG; Zhaoshun; (张兆顺)

    2003-01-01

    The structure of scalar turbulence dissipation is studied by means of direct numerical simulation. It has been discovered that the scalar turbulence dissipation exhibits thin layer structure. Based on the analysis of transportation equation of scalar turbulence dissipation, we have investigated the effect of turbulent strains on the generation of scalar turbulence dissipation and found that fluctuating scalar gradients trend to the third principal direction of turbulent strains. Therefore the generation of the thin layer structure of scalar turbulence dissipation is well interpreted.

  13. Thin Capitalization Rules and Multinational Firm Capital Structure

    NARCIS (Netherlands)

    Blouin, J.; Huizinga, H.P.; Laeven, L.; Nicodeme, G.

    2014-01-01

    Abstract: This paper examines the impact of thin capitalization rules that limit the tax deductibility of interest on the capital structure of the foreign affiliates of US multinationals. We construct a new data set on thin capitalization rules in 54 countries for the period 1982-2004. Using confide

  14. Atomic Structure Control of Silica Thin Films on Pt(111)

    KAUST Repository

    Crampton, Andrew S

    2015-05-27

    Metal oxide thin films grown on metal single crystals are commonly used to model heterogeneous catalyst supports. The structure and properties of thin silicon dioxide films grown on metal single crystals have only recently been thoroughly characterized and their spectral properties well established. We report the successful growth of a three- dimensional, vitreous silicon dioxide thin film on the Pt(111) surface and reproduce the closed bilayer structure previously reported. The confirmation of the three dimensional nature of the film is unequivocally shown by the infrared absorption band at 1252 cm−1. Temperature programmed desorption was used to show that this three-dimensional thin film covers the Pt(111) surface to such an extent that its application as a catalyst support for clusters/nanoparticles is possible. The growth of a three-dimensional film was seen to be directly correlated with the amount of oxygen present on the surface after the silicon evaporation process. This excess of oxygen is tentatively attributed to atomic oxygen being generated in the evaporator. The identification of atomic oxygen as a necessary building block for the formation of a three-dimensional thin film opens up new possibilities for thin film growth on metal supports, whereby simply changing the type of oxygen enables thin films with different atomic structures to be synthesized. This is a novel approach to tune the synthesis parameters of thin films to grow a specific structure and expands the options for modeling common amorphous silica supports under ultra high vacuum conditions.

  15. Effects of Precursor Concentration on Structural and Optical Properties of ZnO Thin Films Grown on Muscovite Mica Substrates by Sol-Gel Spin-Coating.

    Science.gov (United States)

    Kim, Younggyu; Leem, Jae-Young

    2016-05-01

    The structural and optical properties of the ZnO thin films grown on mica substrates for different precursor concentrations were investigated. The surface morphologies of all the samples indicated that they consisted of granular structures with spherical nano-sized crystallites. The thickness of the ZnO thin films increased significantly and the optical band gap exhibited a blue shift with an increase in the precursor concentration. It is remarkable that the highest I(NBE)/I(DLE) ratio was observed for the ZnO thin film with 0.8 M precursor concentration, even though cracks formed on the surface of this film.

  16. Synthesis and structural characterization of two-dimensional hierarchical covellite nano-structures

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Nirupam, E-mail: n.banerjee@utwente.nl [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India); MESA Institute for Nanotechnology, University of Twente, Enschede (Netherlands); Krupanidhi, S.B., E-mail: sbk@mrc.iisc.ernet.in [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India)

    2012-12-14

    We report a simple, template free and low-temperature hydrothermal reaction pathway using Cu(II) - thiourea complex (prepared in situ from copper (II) chloride and thiourea as precursors) and citric acid as complexing agent to synthesize two-dimensional hierarchical nano-structures of covellite (CuS). The product was characterized with the help of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray spectroscopy (EDAX) and X-ray photoelectron spectroscopy (XPS). The concentration of citric acid in the hydrothermal precursor solution was seen to have a profound effect on the nanostructure of the product generated. Based on the outcoming product nano-architecture at different concentration of the ionic surfactant in the hydrothermal precursor solution a possible mechanism suited for reaction and further nucleation is also discussed. -- Highlights: Black-Right-Pointing-Pointer A novel reaction scheme is proposed for synthesizing covellite 2D nano-structures. Black-Right-Pointing-Pointer The nanostructures were thoroughly characterized, both structurally and chemically. Black-Right-Pointing-Pointer Through variation of synthetic parameters a general growth mechanism is proposed.

  17. Monolayer and bilayer structures in ionic liquids and their mixtures confined to nano-films.

    Science.gov (United States)

    Smith, Alexander M; Lovelock, Kevin R J; Perkin, Susan

    2013-01-01

    The confinement of liquids to thin films can lead to dramatic changes in their structural arrangement and dynamic properties. Ionic liquids display nano-structures in the bulk of the liquid, consisting of polar and non-polar domains, whereas a solid surface can induce layered structures in the near-surface liquid. Here we compare and contrast the layer structures in a series of imidazolium and pyrrolidinium-based ionic liquids upon confinement of the liquids to films of approximately 0-20 nm between two negatively charged mica surfaces. Using a surface force balance (SFB) we measured the force between the two atomically smooth mica surfaces with ionic liquid between, directly revealing the ion packing and dimensions of layered structures for each liquid. The ionic liquids with shorter alkyl chain substituents form alternating cation-anion monolayer structures on confinement, whilst a longer alkyl chain leads to alignment of the cations in bilayer formation. The crossover from monolayers to bilayers, however, occurs at different alkyl chain lengths for imidazolium- and pyrrolidinium-based ionic liquids with a common anion. In addition, we find that imidazolium cation bilayers are arranged in toe-to-toe orientation, whereas pyrrolidinium cations form bilayers consisting of fully interdigitated alkyl chains. Results for a mixture of monolayer-preferring (i.e. short alkyl chain) and bilayer-preferring (i.e. long alkyl chain) liquids indicate alkyl chain segregation and bilayer-like structures. We discuss the driving forces for these self-assembly effects, and the contrasting behaviour of the imidazolium and pyrrolidinium-type ionic liquids.

  18. The influence of nano-ceramic modifier on the structure and properties of polyolefin composites

    Science.gov (United States)

    Sudnik, L.; Dubkova, V.; Galinovsky, A.; Osipkov, A.

    2016-10-01

    It has been shown, that the nano-ceramic modifier boehmite, with specific surface area of up to 400 m2/g and dispersion degree of less than100 nm, is a structurally active filler of an ultra-high-molecular-weight polyethylene. The boehmite influences the polymer crystalline and supra-molecular structure, during crystallization of the polymer from the melt under uniaxial plastic deformation conditions. It results in the production of nano-composites with an improved complex of properties.

  19. A Lanthanide MOF Thin-Film Fixed with Co3 O4 Nano-Anchors as a Highly Efficient Luminescent Sensor for Nitrofuran Antibiotics.

    Science.gov (United States)

    Zhang, Feng; Yao, Hua; Chu, Tianshu; Zhang, Gaowei; Wang, Yi; Yang, Yangyi

    2017-08-01

    Nitrofurans are a group of widely used veterinary antibiotics, which have been banned due to antibiotics pollution. Development of a rapid and effective method for the detection of nitrofuran antibiotics (NFAs) is an important challenge. Herein, we designed a chemical sensor based on a thin-film composed of the lanthanide metal-organic framework (Ln-MOF) {[Eu2 (BCA)3 (H2 O)(DMF)3 ]⋅0.5DMF⋅H2 O}n (Eu-BCA, in which BCA is 2,2'-biquinoline-4,4'-dicarboxylate) coated on a cost-effective stainless steel wire mesh (SSWM) by Co3 O4 nano-anchor fixation method. The MOF coatings were well adhered to the SSWM, resulting in a three-dimensional porous, flexible, and processable sensor. The structure of the as-prepared MOF thin-film was confirmed by powder X-ray diffraction (PXRD), and the surface morphology was examined by scanning electron microscopy (SEM). Significantly, the Eu-BCA thin-film was highly selective and sensitive to NFAs, and yet remained unaffected by other common antibiotics that may be present. The limits of detection for nitrofurantoin (NFT) and nitrofurazone (NFZ) are 0.21 and 0.16 μm, respectively. NFAs were also successfully detected in water from the Pearl River in Guangzhou, and from bovine serum samples. Hence, the reported Ln-MOF thin-film is a promising sensor for the detection of NFAs, thereby helping to protect human beings from all manner of hazards that arise from the abuse of antibiotics in livestock breeding. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. 纳米WO_3/玻璃薄膜光催化性能研究%Photocatalysis Performance of Nano-WO_3/Glass Thin Film

    Institute of Scientific and Technical Information of China (English)

    吴永健; 张果龙

    2011-01-01

    以溶胶-凝胶法制备纳米WO3/玻璃薄膜,并用UV-Vis法,IR法和XRD方法进行了表征。以10 mg/L罗丹明B为降解对象,考察其光催化性能。结果表明:经500℃灼烧2 h以上制备的厚度为278 nm的两层涂膜,在pH=3.0、鼓入空气、光强为1.81×1016光子/s等条件下薄膜具有最佳光催化活性,对罗丹明B的光催化降解效率在60 min内达到90%以上。%The nano-tungsten oxide(WO3)/glass thin film prepared by sol-gel method was investigated.The structure and photocatalytic behavior of the tungsten oxide(WO3) thin films was assessed by UV-Vis,XRD and IR.10 mg/L Rhodamine B solution was degradated on the thin film as an object of investigation.The removal ratio of Rhodamine B can reach 90% in 60 min under the condition that the media acidity was pH=3.0,air was plumped to the reactor through a gas pipe,and light intensity of 1.81×1016 photon/s.The two coating layer thin films were calcined at 500 ℃ for 2 h.

  1. PREPARATION OF NANO-CRYSTALLINE Fe-Cu THIN FILMS AND THEIR MAGNETIC PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    X.F.Bi; S.K.Gong; H.B.Xu; K.I.Arai

    2002-01-01

    Fe-Cu thin films of 0.2μm in thickness with different Cu contents were prepared byusing r.f. magnetron sputtering onto glass substrate. The effect of sputtering param-eters, including Ar gas pressure and input rf power, on the structure and magneticproperties was investigated. It was found that when the power is lower than 70W,the structure of the films remained single bcc-Fe phase with Cu solubility of up to50at.%. TEM observations for the bcc-Fe phase showed that the grain size was inthe nanometer range of less than 20nm. The coercivity of Fe-Cu films was largelyaffected by not only Ar gas pressure but also rf power, and reached about 2.5Oe in thepressure of 0.67-6.67Pa and in the power of less than 100W. In addition, saturationmagnetization, with Cu content less than 60at.%, was about proportional to the con-tent of bcc-Fe. When Cu content was at 60at.%, however, saturation magnetizationwas much smaller than its calculation value.

  2. Dynamic stiffness for thin-walled structures by power series

    Institute of Scientific and Technical Information of China (English)

    ZHU Bin; LEUNG A.Y.T.

    2006-01-01

    The dynamic stiffness method is introduced to analyze thin-walled structures including thin-walled straight beams and spatial twisted helix beam. A dynamic stiffness matrix is formed by using frequency dependent shape functions which are exact solutions of the governing differential equations. With the obtained thin-walled beam dynamic stiffness matrices, the thin-walled frame dynamic stiffness matrix can also be formulated by satisfying the required displacements compatibility and forces equilibrium, a method which is similar to the finite element method (FEM). Then the thin-walled structure natural frequencies can be found by equating the determinant of the system dynamic stiffness matrix to zero. By this way, just one element and several elements can exactly predict many modes of a thin-walled beam and a spatial thin-walled frame, respectively. Several cases are studied and the results are compared with the existing solutions of other methods. The natural frequencies and buckling loads of these thin-walled structures are computed.

  3. D. C. plasma-sprayed coatings of nano-structured alumina-titania-silica

    CERN Document Server

    Jiang Xian Liang

    2002-01-01

    nano-crystalline powders of omega(Al sub 2 O sub 3) = 95%, omega(TiO sub 2) = 3%, and omega(SiO sub 2) = 2%, were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps of ball milling, slurry forming, spray drying, and heat treatment. D.C. plasma was used to spray the agglomerated nano-crystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Experimental results show that the agglomerated nano-crystalline particles are spherical, with a size from (10-90) mu m. The flow ability of the nano-crystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nano-structure. Unlike conventional plasma-sprayed coatings, no laminar layer could be found in the nano-structured coatings. Although the nano-structured coatings have a lo...

  4. Optical and Electrical Investigation of ZnO Nano-Wire Array to Micro-Flower from Hierarchical Nano-Rose Structures

    NARCIS (Netherlands)

    Pal, Kaushik; Zhan, Bihong; Ma, Xiao; Wang, Guoping; Schirhagl, Romana; Murgasen, Priya

    We have demonstrated a simple solvo-chemical and solvo-thermal route to design various nano structures growth of zinc oxide (ZnO). The shapes and morphologies can be easily controlled by using different ambient conditions. We successfully fabricated ZnO nano-wires array on ITO substrate. Those

  5. Nano-structured morphological features of pulsed direct current magnetron sputtered Mo films for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Karthikeyan, Sreejith, E-mail: s.karthikeyan@edu.salford.ac.uk; Hill, Arthur E.; Pilkington, Richard D.

    2011-10-31

    Historically, molybdenum thin films have been used as the back contact for Cu(In,Ga)Se{sub 2} based solar cells and as such the properties of these layers play an important role in the overall cell structure. This paper describes the production of molybdenum films using pulsed d.c. magnetron sputtering from compressed molybdenum powder targets. The films were deposited at different substrate temperatures under constant power and constant current modes, and analysed using X-ray diffraction, scanning electron microscopy, atomic force microscopy and four point resistance probe. Mechanical strain and resistivity were found to decrease with substrate temperature together with a shift in the (110) crystallographic plane towards higher diffraction angles. All films were well adhered to the glass substrates irrespective of their high tensile strain. Surface morphology analysis revealed the presence of nano-structured stress relief patterns which can enhance the nucleation sites for subsequent CuInSe{sub 2} deposition. A high-resolution cross sectional image showed the columnar growth of the films. Surface roughness analysis revealed that roughness increased with increase in substrate temperature.

  6. Molecular dynamics simulation of atomic-scale frictional behavior of corrugated nano-structured surfaces.

    Science.gov (United States)

    Kim, Hyun-Joon; Kim, Dae-Eun

    2012-07-01

    Surface morphology is one of the critical parameters that affect the frictional behavior of two contacting bodies in relative motion. It is important because the real contact area as well as the contact stiffness is dictated by the micro- and nano-scale geometry of the surface. In this regard, the frictional behavior may be controlled by varying the surface morphology through nano-structuring. In this study, molecular dynamics simulations were conducted to investigate the effects of contact area and structural stiffness of corrugated nano-structures on the fundamental frictional behavior at the atomic-scale. The nano-structured surface was modeled as an array of corrugated carbon atoms with a given periodicity. It was found that the friction coefficient of the nano-structured surface was lower than that of a smooth surface under specific contact conditions. The effect of applied load on the friction coefficient was dependent on the size of the corrugation. Furthermore, stiffness of the nano-structure was identified to be an important variable in dictating the frictional behavior.

  7. Effect of Precursor Concentration on Structural Optical and Electrical Properties of NiO Thin Films Prepared by Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    Rafia Barir

    2017-01-01

    Full Text Available Undoped nickel oxide (NiO thin films were deposited on 500°C heated glass substrates using spray pyrolysis method at (0.015–0.1 M range of precursor. The latter was obtained by decomposition of nickel nitrate hexahydrate in double distilled water. Effect of precursor concentration on structural, optical, and electrical properties of NiO thin films was investigated. X-ray diffraction (XRD shows the formation of NiO under cubic structure with single diffraction peak along (111 plane at 2θ=37.24°. When precursor concentration reaches 0.1 M, an increment in NiO crystallite size over 37.04 nm was obtained indicating the product nano structure. SEM images reveal that beyond 0.04 M as precursor concentration the substrate becomes completely covered with NiO and thin films exhibit formation of nano agglomerations at the top of the sample surface. Ni-O bonds vibrations modes in the product of films were confirmed by FT-IR analysis. Transparency of the films ranged from 57 to 88% and band gap energy of the films decreases from 3.68 to 3.60 eV with increasing precursor concentration. Electrical properties of the elaborated NiO thin films were correlated to the precursor concentration.

  8. Lighting up the Christmas tree: high-intensity laser interactions with a nano-structured target

    CERN Document Server

    Gonoskov, A; Ilderton, A; Mackenroth, F; Marklund, M

    2014-01-01

    We perform a numerical study of the interaction of a high-intensity laser pulse with a nano-structured target. In particular, we study a target where the nano-structuring increases the absorption rate as compared to the flat target case. The transport of electrons within the target, and in particular in the nano-structure, is analysed. It is shown that it is indeed possible, using a terawatt class laser, to light up a nano-scale Christmas tree. Due to the form of the tree we achieve very strong edge fields, in particular at the top where the star is located. Such edge fields, as here located at ion rich spots, makes strong acceleration gradients possible. It also results in a nice, warm glow suitable for the holiday season.

  9. Form Birefringence in Thin Films with Oblique Columnar Structures

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-Guo; SHAO Jian-Da; WANG Su-Mei; HE Hong-Bo; FAN Zheng-Xiu

    2005-01-01

    @@ Effective medium theory is useful for designing optical elements with form birefringent subwavelength structures. Thinfilms fabricated by oblique deposition are similar to the two-dimensional surface relief subwavelength gratings. We use the effective medium theory to calculate the anisotropic optical properties of the thin films with oblique columnar structures. The effective refractive indices and the directions are calculated from effective medium theory. It is shown that optical thin films with predetermined refractive indices and birefringence may be engineered.

  10. Nano-mechanical Behaviour and Mmicrostructural Evolution of Cu/Si Thin Films at Different Annealing Temperatures

    Directory of Open Access Journals (Sweden)

    Woei-Shyan Lee

    2012-07-01

    Full Text Available This study investigates the nano-mechanical properties of as-deposited Cu/Si thin films indented to a depth of 2000 nm using a nanoindentation technique. Cu films with a thickness of 1800 nm are deposited on (100 silicon substrates and the indented specimens are then annealed at temperatures of 160℃ and 210℃, respectively, using rapid thermal annealing (RTA technique. The results show that the hardness and Young’s modulus of the Cu/Si thin films have maximum values of 0.82 GPa and 95 GPa, respectively. The TEM observations show that the specimens annealed at a temperature of 160℃, the amorphous nature of the microstructure within the indented zone is maintained. However, annealed at a higher temperature of 210℃, the indentation affected zone consists of Copper silicide (η-Cu3Si precipitates are observed in the annealed specimens. Overall, the results presented in this study confirm that the annealing temperature has a significant effect on the formation of η-Cu3Si in nanoindented Cu/Si thin-film systems.

  11. Noninvasive photodetachment of stem cells on tunable conductive polymer nano thin films: selective harvesting and preserved differentiation capacity.

    Science.gov (United States)

    You, Jungmok; Heo, June Seok; Kim, Jeonghun; Park, Teahoon; Kim, Byeonggwan; Kim, Han-Soo; Choi, Youjeong; Kim, Hyun Ok; Kim, Eunkyoung

    2013-05-28

    Viable mesenchymal stem cells (MSCs) were efficiently and selectively harvested by near-infrared (NIR) light using the photothermal effect of a conductive polymer nano thin film. The poly(3,4-ethylenedioxy thiophene) (PEDOT)-coated cell culture surfaces were prepared via a simple and fast solution-casting polymerization (SCP) technique. The absorption of PEDOT thin films in the NIR region was effectively triggered cell harvesting upon exposure to an NIR source. By controlling the NIR absorption of the PEDOT film through electrochemical doping or growing PEDOT with different thin film thickness from 70 to 300 nm, the proliferation and harvesting of MSCs on the PEDOT surface were controlled quantitatively. This light-induced cell detachment method based on PEDOT films provides the temporal and spatial control of cell harvesting, as well as cell patterning. The harvested stem cells were found to be alive and well proliferated despite the use of temperature increase by NIR. More importantly, the harvested MSCs by this method preserved their intrinsic characteristics as well as multilineage differentiation capacities. This PEDOT surfaces could be used for repetitive culture and detachment of MSCs or for efficient selection or depletion of a specific subset from heterogeneous population during culture of various tissue-derived cells because there were no photodegradation and photobreakage in the PEDOT films by NIR exposure.

  12. Dispersive shock waves in Bose-Einstein condensates and nonlinear nano-oscillators in ferromagnetic thin films

    Science.gov (United States)

    Hoefer, Mark A.

    This thesis examines nonlinear wave phenomena, in two physical systems: a Bose-Einstein condensate (BEC) and thin film ferromagnets where the magnetization dynamics are excited by the spin momentum transfer (SMT) effect. In the first system, shock waves generated by steep gradients in the BEC wavefunction are shown to be of the disperse type. Asymptotic and averaging methods are used to determine shock speeds and structure in one spatial dimension. These results are compared with multidimensional numerical simulations and experiment showing good, qualitative agreement. In the second system, a model of magnetization dynamics due to SMT is presented. Using this model, nonlinear oscillating modes---nano-oscillators---are found numerically and analytically using perturbative methods. These results compare well with experiment. A Bose-Einstein condensate (BEC) is a quantum fluid that gives rise to interesting shock wave nonlinear dynamics. Experiments depict a BEC that exhibits behavior similar to that of a shock wave in a compressible gas, e.g. traveling fronts with steep gradients. However, the governing Gross-Pitaevskii (GP) equation that describes the mean field of a BEC admits no dissipation hence classical dissipative shock solutions do not explain the phenomena. Instead, wave dynamics with small dispersion is considered and it is shown that this provides a mechanism for the generation of a dispersive shock wave (DSW). Computations with the GP equation are compared to experiment with excellent agreement. A comparison between a canonical 1D dissipative and dispersive shock problem shows significant differences in shock structure and shock front speed. Numerical results associated with laboratory experiments show that three and two-dimensional approximations are in excellent agreement and one dimensional approximations are in qualitative agreement. The interaction of two DSWs is investigated analytically and numerically. Using one dimensional DSW theory it is argued

  13. Tailoring electronic structure of polyazomethines thin films

    Directory of Open Access Journals (Sweden)

    J. Weszka

    2010-09-01

    Full Text Available Purpose: The aim of this work is to show how electronic properties of polyazomethine thin films deposited by chemical vapor deposition method (CVD can be tailored by manipulating technological parameters of pristine films preparation as well as modifying them while the as-prepared films put into iodine atmosphere.Design/methodology/approach: The recent achievements in the field of designing and preparation methods to be used while preparing polymer photovoltaic solar cells or optoelectronic devices.Findings: The method used allow for pure pristine polymer thin films to be prtepared without any unintentional doping taking place during prepoaration methods. This is a method based on polycondensation process, where polymer chain developing is running directly due to chemical reaction between molecules of bifunctional monomers. The method applied to prepare thin films of polyazomethines takes advantage of monomer transporting by mreans of neutral transport agent as pure argon is.Research limitations/implications: The main disadvantage of alternately conjugated polymers seems to be quite low mobility of charge carrier that is expected to be a consequence of their backbone being built up of sp2 hybridized carbon and nitrogen atoms. Varying technological conditions towards increasing reagents mass transport to the substrate is expected to give such polyazomethine thin films organization that phenylene rin stacking can result in special π electron systems rather than linear ones as it is the case.Originality/value: Our results supply with original possibilities which can be useful in ooking for good polymer materials for optoelectronic and photovoltaic applications. These results have been gained on polyazomethine thin films but their being isoelectronic counterpart to widely used poly p-phenylene vinylene may be very convenient to develop high efficiency polymer solar cells

  14. Defect induced modification of structural, topographical and magnetic properties of zinc ferrite thin films by swift heavy ion irradiation

    Science.gov (United States)

    Raghavan, Lisha; Joy, P. A.; Vijaykumar, B. Varma; Ramanujan, R. V.; Anantharaman, M. R.

    2017-04-01

    Swift heavy ion irradiation provides unique ways to modify physical and chemical properties of materials. In ferrites, the magnetic properties can change significantly as a result of swift heavy ion irradiation. Zinc ferrite is an antiferromagnet with a Neel temperature of 10 K and exhibits anomalous magnetic properties in the nano regime. Ion irradiation can cause amorphisation of zinc ferrite thin films; thus the role of crystallinity on magnetic properties can be examined. The influence of surface topography in these thin films can also be studied. Zinc ferrite thin films, of thickness 320 nm, prepared by RF sputtering were irradiated with 100 MeV Ag ions. Structural characterization showed amorphisation and subsequent reduction in particle size. The change in magnetic properties due to irradiation was correlated with structural and topographical effects of ion irradiation. A rough estimation of ion track radius is done from the magnetic studies.

  15. Successive ion layer adsorption and reaction (SILAR) technique synthesis of Al(III)-8-hydroxy-5-nitrosoquinolate nano-sized thin films: characterization and factors optimization.

    Science.gov (United States)

    Haggag, Sawsan M S; Farag, A A M; Abdel Refea, M

    2013-02-01

    Nano Al(III)-8-hydroxy-5-nitrosoquinolate [Al(III)-(HNOQ)(3)] thin films were synthesized by the rapid, direct, simple and efficient successive ion layer adsorption and reaction (SILAR) technique. Thin film formation optimized factors were evaluated. Stoichiometry and structure were confirmed by elemental analysis and FT-IR. The particle size (27-71 nm) was determined using scanning electron microscope (SEM). Thermal stability and thermal parameters were determined by thermal gravimetric analysis (TGA). Optical properties were investigated using spectrophotometric measurements of transmittance and reflectance at normal incidence. Refractive index, n, and absorption index, k, were determined. Spectral behavior of the absorption coefficient in the intrinsic absorption region revealed a direct allowed transition with 2.45 eV band gap. The current-voltage (I-V) characteristics of [Al(III)-(HNOQ)(3)]/p-Si heterojunction was measured at room temperature. The forward and reverse I-V characteristics were analyzed. The calculated zero-bias barrier height (Φ(b)) and ideality factor (n) showed strong bias dependence. Energy distribution of interface states (N(ss)) was obtained.

  16. Successive ion layer adsorption and reaction (SILAR) technique synthesis of Al(III)-8-hydroxy-5-nitrosoquinolate nano-sized thin films: Characterization and factors optimization

    Science.gov (United States)

    Haggag, Sawsan M. S.; Farag, A. A. M.; Abdel Refea, M.

    2013-02-01

    Nano Al(III)-8-hydroxy-5-nitrosoquinolate [Al(III)-(HNOQ)3] thin films were synthesized by the rapid, direct, simple and efficient successive ion layer adsorption and reaction (SILAR) technique. Thin film formation optimized factors were evaluated. Stoichiometry and structure were confirmed by elemental analysis and FT-IR. The particle size (27-71 nm) was determined using scanning electron microscope (SEM). Thermal stability and thermal parameters were determined by thermal gravimetric analysis (TGA). Optical properties were investigated using spectrophotometric measurements of transmittance and reflectance at normal incidence. Refractive index, n, and absorption index, k, were determined. Spectral behavior of the absorption coefficient in the intrinsic absorption region revealed a direct allowed transition with 2.45 eV band gap. The current-voltage (I-V) characteristics of [Al(III)-(HNOQ)3]/p-Si heterojunction was measured at room temperature. The forward and reverse I-V characteristics were analyzed. The calculated zero-bias barrier height (Φb) and ideality factor (n) showed strong bias dependence. Energy distribution of interface states (Nss) was obtained.

  17. Analysis of the Carbon Nano-Structures Formation in Liquid Arcing

    Institute of Scientific and Technical Information of China (English)

    XING Gang; JIA Shen-li; XING Jian; SHI Zong-qian

    2007-01-01

    Graphite electrodes were used for the direct current (DC) arc discharge in water.And high-resolution transmission electron microscopy (HRTEM) was used to investigate the products.Based on the experimental phenomena and nano-structure products,arc plasma characteristics in water were analyzed theoretically.Two growth regions and relevant growth modes were proposed to interpret the formation mechanisms of nano-struetures by are discharge in water.Furthermore,liquid nitrogen and cross magnetic field was applied to change the arcing state respectively,and new carbon nano-struetures were obtained.Their formation mechanisms were also analyzed correspondingly.

  18. Book Review: Nano physics & Nano technology

    Directory of Open Access Journals (Sweden)

    Abdolkhaled Zaree

    2012-12-01

    Full Text Available During last decades, there are a lot of emphases on studying material behavior in atomic scale. In most scientific and engineering fields, one can see the effect of nanotechnology. The aim of nanoscience is to design and fabrication of new and applicable materials. Nowadays, Nano is a popular science which chemists, physicist, doctors, engineers, financial managers and environment's fans for creating a good life via nanoscience have a great cooperation with each others. Materials in nano scale such as nanotubes and nanowires have extraordinary properties which by optimization of these properties in nano scale and then develop these properties to macro scale, they've been challenging issues. For instance, materials in nano scale improve mechanical properties of polymers and metallic materials via nano particles and on the other hand by producing a thin film on surfaces improve surface hardening. Besides, nanotechnology is in hi-tech industries such as magnetic devices, surface coating, and biomaterial, material having sensors, polymers, gels, ceramics and intelligent membrane. Nano-carbon tubes are considered intelligent due to the fact that they couple electrochemical and elastic properties simultaneously, hence have greater activation energy density in comparison with other intelligent materials. Studying nanoscience is important because it causes the life to be better. Future Materials and structures will have a lot of outstanding properties. Intelligent machines can repair, recycle and reconstruct themselves. All these features are only possible in nano zone. Nano in engineering science can provide the possibility of making light missiles for exploring space. The reduced weight can be achieved by replacing traditional materials with hybrid nanocomposites.

  19. On hydrophilicity improvement of the porous anodic alumina film by hybrid nano/micro structuring

    Science.gov (United States)

    Wang, Weichao; Zhao, Wei; Wang, Kaige; Wang, Lei; Wang, Xuewen; Wang, Shuang; Zhang, Chen; Bai, Jintao

    2017-09-01

    In both, laboratory and industry, tremendous attention is paid to discover an effective technique to produce uniform, controllable and (super) hydrophilic surfaces over large areas that are useful in a wide range of applications. In this investigation, by combing porous anodic alumina (PAA) film with nano-structures and microarray of aluminum, the hydrophilicity of hybrid nano-micro structure has been significantly improved. It is found some factors can affect the hydrophilicity of film, such as the size and aspect ratio of microarray, the thickness of nano-PAA film etc. Comparing with pure nano-PAA films and microarray, the hybrid nano-micro structure can provide uniform surface with significantly better hydrophilicity. The improvement can be up to 84%. Also, this technique exhibits good stability and repeatability for industrial production. By optimizing the thickness of nano-PAA film and aspect ratio of micro-structures, super-hydrophilicity can be reached. This study has obvious prospect in the fields of chemical industry, biomedical engineering and lab-on-a-chip applications.

  20. On the shear strength of tungsten nano-structures with embedded helium

    Science.gov (United States)

    Smirnov, R. D.; Krasheninnikov, S. I.

    2013-08-01

    Modification of plastic properties of tungsten nano-structures under shear stress load due to embedded helium atoms is studied using molecular dynamics modelling. The modelling demonstrates that the yield strength of tungsten nano-structures reduces significantly with increasing embedded helium concentration. At high helium concentrations (>10 at%), the yield strength decreases to values characteristic to the pressure in helium nano-bubbles, which are formed in tungsten under such conditions and thought to be responsible for the formation of nano-fuzz on tungsten surfaces irradiated with helium plasma. It is also shown that tungsten plastic flow strongly facilitates coagulation of helium clusters to larger bubbles. The temperature dependencies of the yield strength are obtained.

  1. Photocatalytic degradation of methyl orange by nano-TiO_2 thin films prepared by RF magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    Fanming Meng; Ling Cao; Xueping Song; Zhaoqi Sun

    2009-01-01

    Nano-TiO_2 thin films are deposited by radio frequency (RF) magnetron sputtering using TiO_2 ceramic target and characterized by X-ray diffractometer,atomic force microscope,and ultraviolet-visible spectrophotometer.The photocatalytic activity is evaluated by light-induced degradation of methyl orange solutions (5,10,and 20 ppm) using a high pressure mercury lamp as the light source.The film is amorphous,and its energy gap is 3.02 Ev.The photocatalytic degradation of methyl orange solution is the first-order reaction and the apparent reaction rate constants are 0.00369,0.0024,and 0.00151 for the methyl orange solution concentrations of 5,10,and 20 ppm,respectively.

  2. Design, fabrication and characterization of a high-sensitivity pressure sensor based on nano-polysilicon thin film transistors

    Directory of Open Access Journals (Sweden)

    Xiaofeng Zhao

    2015-12-01

    Full Text Available Based on the nano-polysilicon thin film transistors (TFTs, a high-sensitivity pressure sensor was designed and fabricated in this paper. The pressure sensing element is composed of a Wheatstone bridge with four nano-polysilicon TFTs designed on different positions of the square silicon diaphragm. Via taking the four channel resistors of the TFTs as piezoresistors, the measurement to the external pressure can be realized according to the piezoresistive effects of channel layer. Through adopting complementary metal oxide semiconductor (CMOS technology and micro-electromechanical system (MEMS technology, the chips of sensor were fabricated on orientation silicon wafer with a high resistivity. At room temperature, when applying a voltage 5.0 V to the Wheatstone bridge, the full scale (100 kPa output voltage and the sensitivity of the sensor with 35 μm-thick silicon diaphragm are 267 mV and 2.58 mV/kPa, respectively. The experimental results show that the pressure sensors can achieve a much higher sensitivity.

  3. A hetero-structured ring discovered by CAS nano-scientists

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Teaming up with co-workers,researchers from the CAS-affiliated National Center for Nanoscience and Technology(NCNST) recently succeeded in fabricating a hetero-structured nano-ring in their laboratory. The feat, scientist believe, would be valuable for developing new optical or electronic nano-elements and related devices in the near future.The work was recently reported by Advanced Materials (Vol. 19, 2319-2323, 2007).

  4. Synthesis of tungsten oxide nano structures by laser pyrolysis

    CSIR Research Space (South Africa)

    Mwakikunga, BW

    2008-01-01

    Full Text Available Since the proposal to synthesise materials by laser assisted pyrolysis in the 1970s, and its practical realisation in 1982, a number of researchers have used this method in obtaining nano-powders from liquid droplets. This study revisits...

  5. Fabrication and analysis of nano-structured thermal spraying feeds

    Institute of Scientific and Technical Information of China (English)

    YE Xiong-lin; MA Shi-ning; LI Chang-qing

    2004-01-01

    A kind of thermal spray nanostructured Al2O3 and TiO2 feeds fabricating technology was investigated.Agglomerated nanogranules prepared by spray drying were heat treated in order to be dense, and there were two sintering technologies used, i.e. high temperature electric furnace sintering and high velocity flame sintering, respectively. The results indicate feeds phase components using high temperature electric furnace sintering at 1 200 ℃,1 300 ℃ and 1 400 ℃ do not change, and grain sizes of nano-Al2O3 and TiO2 grow little at 1 200 ℃ and 1 300 ℃,while grain sizes of nano-Al2O3 and TiO2 grow obviously, and the grain size of nano-TiO2 is larger than 100 nm at 1400 ℃. Phase components of the feeds using high velocity flame sintering change, where α-Al2O3 changes to γ-Al2O3 and rutile TiO2 changes to brookite TiO2, though grain size of nano-Al2O3 does not grow and is less than 100 nm because cooling velocity is too quick. Compared with these two heat treatment technology, the technology using electric furnace to treat nanostructured Al2O3 and TiO2 feeds is more suitable.

  6. Thin-walled reinforcement lattice structure for hollow CMC buckets

    Energy Technology Data Exchange (ETDEWEB)

    de Diego, Peter

    2017-06-27

    A hollow ceramic matrix composite (CMC) turbine bucket with an internal reinforcement lattice structure has improved vibration properties and stiffness. The lattice structure is formed of thin-walled plies made of CMC. The wall structures are arranged and located according to high stress areas within the hollow bucket. After the melt infiltration process, the mandrels melt away, leaving the wall structure to become the internal lattice reinforcement structure of the bucket.

  7. Comparison of 3 methods on fabricating micro- /nano- structured surface on 3D mold cavity

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard; Bissacco, Giuliano

    2015-01-01

    The methods to manufacture micro- or nano- structures on surfaces have been an area of intense investigation. Demands are shown for technologies for surface structuring on real 3D parts in many fields. However, most technologies for the fabrication of micro-structured functional surfaces are stil...

  8. Optical and Structural Properties of Ultra-thin Gold Films

    CERN Document Server

    Kossoy, Anna; Simakov, Denis; Leosson, Kristjan; Kéna-Cohen, Stéphane; Maier, Stefan A

    2014-01-01

    Realizing laterally continuous ultra-thin gold films on transparent substrates is a challenge of significant technological importance. In the present work, formation of ultra-thin gold films on fused silica is studied, demonstrating how suppression of island formation and reduction of plasmonic absorption can be achieved by treating substrates with (3-mercaptopropyl) trimethoxysilane prior to deposition. Void-free fi lms with deposition thickness as low as 5.4 nm are realized and remain structurally stable at room temperature. Based on detailed structural analysis of the fi lms by specular and diffuse X-ray reflectivity measurements, it is shown that optical transmission properties of continuous ultra-thin films can be accounted for using the bulk dielectric function of gold. However, it is important to take into account the non-abrupt transition zone between the metal and the surrounding dielectrics, which extends through several lattice constants for the laterally continuous ultra-thin films (film thickness...

  9. Static and dynamic buckling of thin-walled plate structures

    CERN Document Server

    Kubiak, Tomasz

    2013-01-01

    This monograph deals with buckling and postbuckling behavior of thin plates and thin-walled structures with flat wall subjected to static and dynamic load. The investigations are carried out in elastic range. The basic assumption here is the  thin plate theory. This method is used to determination the buckling load and postbuckling analysis of thin-walled structures subjected to static and dynamic load. The book introduces two methods for static and dynamic buckling investigation which allow for a wider understanding of the phenomenon. Two different methods also can allow uncoupling of the phenomena occurring at the same time and attempt to estimate their impact on the final result. A general mathematical model, adopted in proposed analytical-numerical method, enables the consideration of all types of stability loss i.e.local, global and interactive forms of buckling. The applied numerical-numerical method includes adjacent of walls, shear-lag phenomenon and a deplanation of cross-sections.

  10. Thin Capitalization Rules and Entrepreneurial Capital Structure Decisions

    Directory of Open Access Journals (Sweden)

    Alexandra Maßbaum

    2009-12-01

    Full Text Available Tax planners often choose debt over equity financing. As this has led to increased corporate debt financing, many countries have introduced thin capitalization rules to secure their tax revenues. In a general capital structure model we analyze if thin capitalization rules affect dividend and financing decisions, and whether they can partially explain why corporations receive both debt and equity capital. We model the Belgian, German and Italian rules as examples. We find that the so-called Miller equilibrium and definite financing effects depend significantly on the underlying tax system. Further, our results are useful for the treasury to decide what thin capitalization type to implement.

  11. Organic/Inorganic Nano-hybrids with High Dielectric Constant for Organic Thin Film Transistor Applications

    Science.gov (United States)

    Yu, Yang-Yen; Jiang, Ai-Hua; Lee, Wen-Ya

    2016-11-01

    The organic material soluble polyimide (PI) and organic-inorganic hybrid PI-barium titanate (BaTiO3) nanoparticle dielectric materials (IBX, where X is the concentration of BaTiO3 nanoparticles in a PI matrix) were successfully synthesized through a sol-gel process. The effects of various BaTiO3 contents on the hybrid film performance and performance optimization were investigated. Furthermore, pentacene-based organic thin film transistors (OTFTs) with PI-BaTiO3/polymethylmethacrylate or cyclic olefin copolymer (COC)-modified gate dielectrics were fabricated and examined. The hybrid materials showed effective dispersion of BaTiO3 nanoparticles in the PI matrix and favorable thermal properties. X-ray diffraction patterns revealed that the BaTiO3 nanoparticles had a perovskite structure. The hybrid films exhibited high formability and planarity. The IBX hybrid dielectric films exhibited tunable insulating properties such as the dielectric constant value and capacitance in ranges of 4.0-8.6 and 9.2-17.5 nF cm-2, respectively. Adding the modified layer caused the decrease of dielectric constant values and capacitances. The modified dielectric layer without cross-linking displayed a hydrophobic surface. The electrical characteristics of the pentacene-based OTFTs were enhanced after the surface modification. The optimal condition for the dielectric layer was 10 wt% hybrid film with the COC-modified layer; moreover, the device exhibited a threshold voltage of 0.12 V, field-effect mobility of 4.32 × 10-1 cm2 V-1 s-1, and on/off current of 8.4 × 107.

  12. Study on thin film lubrication in the nano scale%纳米薄膜润滑研究

    Institute of Scientific and Technical Information of China (English)

    温诗铸; 雒建斌

    2001-01-01

    该文是近年来作者关于纳米薄膜润滑的研究的全面总结。首先介绍了纳米量级润滑膜厚度测量技术,进而系统地阐述了润滑理论中存在的两个尚未完全弄清的问题,即弹流润滑和边界润滑之间润滑状态的形态特征以及润滑膜的失效准则,包括:1)薄膜润滑作为弹流润滑与边界润滑之间一种新的润滑状态的性能特征;2)薄膜润滑的物理模型,弹流润滑与薄膜润滑间的转化关系以及膜厚与工况因子的相关性;3)纳米润滑膜时间效应及其产生原因;4)电场对纳米润滑膜特性的影响;5)纳米润滑膜的失效准则;6)新的润滑状态判断准则。%he summary of recent research about thin film lubrication (TFL)in the nano scale is made. First, the measuring technique of film thickness in the nano scale is introduced. Then, the two problems unsettled completely in lubrication theory, such as the characteristics of the lubrication regime between elasto- hydrodynamic lubrication (EHL) and boundary lubrication (BL), and the failure criterion of the lubricant film, are expounded systematically. They include: 1) the characteristics of TFL as a new lubrication regime between EHL and BL, 2) physical model of TFL, transition conditions from EHL to TFL and the relationship between the film thickness and operating parameters, 3) the time effect of lubricating film in the nano scale and the reason of its creation, 4) the effect of external electric field on the nanotribological properties of lubricant film, 5) the failure criterion of lubricant film in the nano scale, 6) a new method distinguishing lubrication regimes.

  13. Nano-structure TiO2 film coating on 316L stainless steel via sol-gel technique for blood compatibility improvement

    Directory of Open Access Journals (Sweden)

    Mohammadreza Foruzanmehr

    2014-04-01

    Full Text Available   Objective(s: Titanium oxides are known to be appropriate hemocompatible materials which are suggested as coatings for blood-contacting devices. Little is known about the influence of nanometric crystal structure, layer thickness, and semiconducting characteristics of TiO2 on blood hemostasis.   Materials and Methods: Having used sol-gel dip coating method in this study, TiO2 thin films were deposited on nano-scale electro-polished stainless steel 316L with 1 to 5 nano-sized layers. Surface morphology and structure of the film were studied with X-ray diffraction and atomic force microscopy. Blood compatibility was also determined by measuring the platelet activation (CD62P expression, platelet adhesion (Scanning Electron Microscopy, and the blood clotting time on these samples. Results: The films were compact and smooth and existed mainly in the form of anatase. By increasing the number of TiO2 thin layer, clotting time greatly extended, and the population of activated platelet and P-selectine expression changed according to the surface characteristics of each layer. Conclusion: The findings revealed that stainless steel 316L coated with nano-structured TiO2 layer improved blood compatibility, in terms of both blood platelet activity and coagulation cascade, which can decrease the thrombogenicity of blood contacting devices which were made from stainless steel.

  14. Anomalous behavior of B1g mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO thin films

    Directory of Open Access Journals (Sweden)

    Subodh K. Gautam

    2015-12-01

    Full Text Available The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO2 lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb+5 in the TiO2 lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR spectra of films with small size crystallites shows stiffening of about 4 cm−1 for the Eg(1 mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B1g mode exhibits a large anomalous softening of 20 cm−1 with asymmetrical broadening; which was not reported for the case of pure TiO2 crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb5+ doping induced reduction of Ti4+ ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

  15. Aqueous phase deposition of dense tin oxide films with nano-structured surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Yoshitake, E-mail: masuda-y@aist.go.jp; Ohji, Tatsuki; Kato, Kazumi

    2014-06-01

    Dense tin oxide films were successfully fabricated in an aqueous solution. The pH of the solutions was controlled to pH 1.3 by addition of HCl. Precise control of solution condition and crystal growth allowed us to obtain dense tin oxide films. Concave–convex surface of fluorine-doped tin oxide (FTO) substrates was entirely-covered with the continuous films. The films were about 65 nm in thickness and had nano-structured surfaces. Morphology of the films was strikingly different from our previous reported nano-sheet assembled structures. The films were not removed from the substrates by strong water flow or air blow to show strong adhesion strength. The aqueous solution process can be applied to surface coating of various materials such as nano/micro-structured surfaces, particles, fibers, polymers, metals or biomaterials. - Graphical abstract: Dense tin oxide films of 65 nm were successfully fabricated in an aqueous solution. They had nano-structured surfaces. Concave-convex substrates were entirely-covered with the continuous films. - Highlights: • Dense tin oxide films of 65 nm were successfully fabricated in an aqueous solution. • They had nano-structured surfaces. • Concave–convex substrates were entirely-covered with the continuous films.

  16. Drag reduction in ultrahydrophobic channels with micro-nano structured surfaces

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of experiments have been performed to demonstrate the significant drag reduction of the laminar flow in the ultrahydrophobic channels with dual-scale micro-nano structured surfaces.However,in previous experiments,the ultrahydrophobic surfaces were fabricated with micro-structures or nano-structures and the channels were on the microscale.For the drag reduction in macro-scale channels few reports are available.Here a new method was developed to fabricate ultrahydrophobic surfaces with micro-nano hierarchical structures made from carbon nanotubes.The drag reductions up to 36.3% were observed in the macro-channels with ultrahydrophobic surfaces.The micro-PIV was used to measure the flow velocity in channels.Compared with the traditional no-slip theory at walls,a significant slip velocity was observed on the ultrahydrophobic surfaces.

  17. Could Nano-Structured Materials Enable the Improved Pressure Vessels for Deep Atmospheric Probes?

    Science.gov (United States)

    Srivastava, D.; Fuentes, A.; Bienstock, B.; Arnold, J. O.

    2005-01-01

    A viewgraph presentation on the use of Nano-Structured Materials to enable pressure vessel structures for deep atmospheric probes is shown. The topics include: 1) High Temperature/Pressure in Key X-Environments; 2) The Case for Use of Nano-Structured Materials Pressure Vessel Design; 3) Carbon based Nanomaterials; 4) Nanotube production & purification; 5) Nanomechanics of Carbon Nanotubes; 6) CNT-composites: Example (Polymer); 7) Effect of Loading sequence on Composite with 8% by volume; 8) Models for Particulate Reinforced Composites; 9) Fullerene/Ti Composite for High Strength-Insulating Layer; 10) Fullerene/Epoxy Composite for High Strength-Insulating Layer; 11) Models for Continuous Fiber Reinforced Composites; 12) Tensile Strength for Discontinuous Fiber Composite; 13) Ti + SWNT Composites: Thermal/Mechanical; 14) Ti + SWNT Composites: Tensile Strength; and 15) Nano-structured Shell for Pressure Vessels.

  18. Control of Exciton Photon Coupling in Nano-structures

    Science.gov (United States)

    Liu, Xiaoze

    In this thesis, we study the interaction of excitons with photons and plasmons and methods to control and enhance this interaction. This study is categorized in three parts: light-matter interaction in microcavity structures, direct dipole-dipole interactions, and plasmon-exciton interaction in metal-semiconductor systems. In the microcavity structures, the light-matter interactions become significant when the excitonic energy is in resonance with microcavity photons. New hybrid quantum states named polariton states will be formed if the strong coupling regime is achieved, where the interaction rate is faster than the average decay rate of the excitons and photons. Polaritons have been investigated in zinc oxide (ZnO) nanoparticles based microcavity at room temperature and stimulated emission of the polaritons has also been observed with a low optical pump threshold. Exictons in organic semiconductors (modeled as Frenkel excitons) are tightly bound to molecular sites, and differ considerably from loosely bound hydrogen atom-like inorganic excitons (modeled as Wannier-Mott excitons). This fundamental difference results in distinct optoelectronic properties. Not only strongly coupled to Wannier-Mott excitons in ZnO, the microcavity photons have also been observed to be simultaneously coupled to Frenkel excitons in 3,4,7,8-naphthalene tetracarboxylic dianhydride (NTCDA). The photons here act like a glue combining Wannier-Mott and Frenkel excitons into new hybrid polaritons taking the best from both constituents. Two-dimensional (2D) excitons in monolayer transition metal dichalcogenides (TMDs) have emerged as a new and fascinating type of Wannier-Mott-like excitons due to direct bandgap transition, huge oscillator strength and large binding energy. Monolayer molybdenum disulfide (MoS2) has been incorporated into the microcavity structure and 2D exciton-polaritons have been observed for the first time with directional emission in the strong coupling regime. Valley

  19. Critical review of the safety assessment of nano-structured silica additives in food.

    Science.gov (United States)

    Winkler, Hans Christian; Suter, Mark; Naegeli, Hanspeter

    2016-06-10

    The development of nano-materials is viewed as one of the most important technological advances of the 21st century and new applications of nano-sized particles in the production, processing, packaging or storage of food are expected to emerge soon. This trend of growing commercialization of engineered nano-particles as part of modern diet will substantially increase oral exposure. Contrary to the proven benefits of nano-materials, however, possible adverse health effects have generally received less attention. This problem is very well illustrated by nano-structured synthetic amorphous silica (SAS), which is a common food additive since several decades although the relevant risk assessment has never been satisfactorily completed. A no observed adverse effect level of 2500 mg SAS particles/kg body weight per day was derived from the only available long-term administration study in rodents. However, extrapolation to a safe daily intake for humans is problematic due to limitations of this chronic animal study and knowledge gaps as to possible local intestinal effects of SAS particles, primarily on the gut-associated lymphoid system. This uncertainty is aggravated by digestion experiments indicating that dietary SAS particles preserve their nano-sized structure when reaching the intestinal lumen. An important aspect is whether food-borne particles like SAS alter the function of dendritic cells that, embedded in the intestinal mucosa, act as first-line sentinels of foreign materials. We conclude that nano-particles do not represent a completely new threat and that most potential risks can be assessed following procedures established for conventional chemical hazards. However, specific properties of food-borne nano-particles should be further examined and, for that purpose, in vitro tests with decision-making cells of the immune system are needed to complement existing in vivo studies.

  20. A two-layer structured PbI2 thin film for efficient planar perovskite solar cells

    Science.gov (United States)

    Ying, Chao; Shi, Chengwu; Wu, Ni; Zhang, Jincheng; Wang, Mao

    2015-07-01

    In this paper, a two-layer structured PbI2 thin film was constructed by the spin-coating procedure using a 0.80 M PbI2 solution in DMF and subsequent close-spaced vacuum thermal evaporation using PbI2 powder as a source. The bottom PbI2 thin film was compact with a sheet-like appearance, parallel to the FTO substrate, and can be easily converted to a compact perovskite thin film to suppress the charge recombination of the electrons of the TiO2 conduction band and the holes of the spiro-OMeTAD valence band. The top PbI2 thin film was porous with nano-sheet arrays, perpendicular to the FTO substrate, and can be easily converted to a porous perovskite thin film to improve the hole migration from the perovskite to spiro-OMeTAD and the charge separation at the perovskite/spiro-OMeTAD interface. The planar perovskite solar cells based on the two-layer structured PbI2 thin film exhibited a photoelectric conversion efficiency of 11.64%, along with an open-circuit voltage of 0.90 V, a short-circuit photocurrent density of 19.29 mA cm-2 and a fill factor of 0.67.

  1. Experimental research on buckling of thin films in nano-scale under mechanical and thermal loading

    Science.gov (United States)

    Wang, S. B.; Jia, H. K.; Ren, X. C.; Li, L. A.

    2008-11-01

    In this paper, the mechanical and thermal properties of compressed thin film titanium films with 150nm thickness deposited on an organic glass substrate under mechanical and thermal loads were measured and characterized. In order to simulate the thin films in IT which subjected compound loads and to produce the buckle modes, the external uniaxial compression and thermal loading are subjected to the specimen by the symmetric loading device and the electrical resistance film in this experiment. The temperature of the thin film deposited on substrate was measured using thermoelectric couple. The range of temperature accords with the temperature range of the MEMS. It is found that the size and number of the delamination and buckling of the film are depended upon the pre-fixed mechanical loading. The transient conduction and thermal stability of the film and substrate was studied with finite element method.

  2. Photonic and plasmonic structures for enhancing efficiency of thin film silicon solar cells

    Science.gov (United States)

    Pattnaik, Sambit

    Crystalline silicon solar cells use high cost processing techniques as well as thick materials that are ˜ 200µm thick to convert solar energy into electricity. From a cost viewpoint, it is highly advantageous to use thin film solar cells which are generally made in the range of 0.1-3µm in thickness. Due to this low thickness, the quantity of material is greatly reduced and so is the number and complexity of steps involved to complete a device, thereby allowing a continuous processing capability improving the throughput and hence greatly decreasing the cost. This also leads to faster payback time for the end user of the photovoltaic panel. In addition, due to the low thickness and the possibility of deposition on flexible foils, the photovoltaic (PV) modules can be flexible. Such flexible PV modules are well suited for building-integrated applications and for portable, foldable, PV power products. For economical applications of solar cells, high efficiency is an important consideration. Since Si is an indirect bandgap material, a thin film of Si needs efficient light trapping to achieve high optical absorption. The previous work in this field has been mostly based on randomly textured back reflectors. In this work, we have used a novel approach, a periodic photonic and plasmonic structure, to optimize current density of the devices by absorbing longer wavelengths without hampering other properties. The two dimensional diffraction effect generated by a periodic structure with the plasmonic light concentration achieved by silver cones to efficiently propagate light in the plane at the back surface of a solar cell, achieves a significant increase in optical absorption. Using such structures, we achieved a 50%+ increase in short circuit current in a nano-crystalline (nc-Si) solar cell relative to stainless steel. In addition to nc-Si solar cells on stainless steel, we have also used the periodic photonic structure to enhance optical absorption in amorphous cells and

  3. Achieving Thin Films with Micro/Nano-Scale Controllable Morphology by Glancing Angle Deposition Technique

    Institute of Scientific and Technical Information of China (English)

    JIANG Shao-Ji; WANG Chao-Yi; TANG Ji-Jia; HU Lin-Xin

    2008-01-01

    @@ We demonstrate that thin films with micro/nanometre controllable morphology can be fabricated by the glancing angle deposition (GLAD) technique which is a physical vapour deposition technique.In this technique, there are parameters which determine the morphology of the thin films: the incident angle, ratio of the deposition rate with respect to the substrate rotation rate, nature of the material being deposited, etc.We fabricate the morphology of column, pillar, helices, zigzag and study the parameters which determine morphology by given some examples of SEM.

  4. Copper doped nickel ferrite nano-crystalline thin films: A potential gas sensor towards reducing gases

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Pratibha; Godbole, R.V.; Bhagwat, Sunita, E-mail: smb.agc@gmail.com

    2016-03-01

    NiFe{sub 2}O{sub 4} and (1 wt% and 3 wt%) Cu:NiFe{sub 2}O{sub 4} thin films have been fabricated using spray pyrolysis deposition technique at 350 °C and then sintered at 650 °C for 3 h. X-ray diffraction, SEM, EDAX, UV-VIS spectroscopy, SQUID VSM were carried out to investigate phase formation, microstructural and influence of Cu doping on magnetic properties of NiFe{sub 2}O{sub 4} thin films. The gas response towards various gases viz. ethanol, Liquid Petroleum Gas (LPG), methanol and hydrogen sulfide (H{sub 2}S) is investigated. The results of XRD revealed that all samples had shown the principal phase of nickel ferrite and the lattice parameter was found to vary from 8.294 Å to 8.314 Å on an incorporation of Cu, and the crystalline sizes were about 40–45 nm. The effect of Cu concentration on saturation magnetization and coercive force were studied. The maximum value of saturation magnetization calculated from hysteresis loop was 89.16 emu/g at room temperature and 96.88 emu/g at 50 K. Cu content on the film surface was found to be maximum for 1 wt% Cu:NiFe{sub 2}O{sub 4} thin film and this film showed an improved response towards all gases. Response of ethanol for NiFe{sub 2}O{sub 4} thin film was found to be higher as compared to all the other gases. The lowering of the optimum operating temperature is observed in 1 wt% Cu:NiFe{sub 2}O{sub 4} thin film with higher selectivity towards ethanol than other gases. All results indicated that the Cu doping in nickel ferrite thin films has a significant influence on the properties. - Highlights: • Cu:NiFe{sub 2}O{sub 4} thin films are synthesized by low cost spray pyrolysis technique. • Addition of Cu content improves magnetic properties. • Cu content on the surface of the film enhances the gas response. • NiFe{sub 2}O{sub 4} thin films exhibit predominant selectivity towards ethanol. • 1 wt% Cu:NiFe{sub 2}O{sub 4} film responses towards ethanol at lower optimum temperature.

  5. Structuring of functional thin films and surfaces with picosecond-pulsed lasers

    Science.gov (United States)

    Raciukaitis, G.; Gecys, P.; Gedvilas, M.; Voisiat, B.

    2012-03-01

    During the recent few years picosecond lasers have been proved as a reliable tool for microfabrication of diverse materials. We present results of our research on structuring of thin films and surfaces using the direct laser writing and the laser beam interference ablation techniques. The processes of micro-pattering were developed for metallic, dielectric films as well as complex multi-layer structures of thin-film solar cells as a way to manufacture frequency-selective surfaces, fine optical components and integrated series interconnects for photovoltaics. Technologies of nano-structuring of surfaces of advanced technical materials such as tungsten carbide were developed using picosecond lasers as well. Experimental work was supported by modeling and simulation of energy coupling and dissipation inside the layers. Selectiveness of the ablation process is defined by optical and mechanical properties of the materials, and selection of the laser wavelength facilitated control of the structuring process. Implementation of the technologies required fine adjustment of spatial distribution of laser irradiation, therefore both techniques are benefiting from shaping the laser beam with diffractive optical elements. Utilization of the whole laser energy included beam splitting and multi-beam processing.

  6. Linear and nonlinear optical investigations of nano-scale Si-doped ZnO thin films: spectroscopic approach

    Science.gov (United States)

    Jilani, Asim; Abdel-wahab, M. Sh.; Zahran, H. Y.; Yahia, I. S.; Al-Ghamdi, Attieh A.

    2016-09-01

    Pure and Si-doped ZnO (SZO) thin films at different concentration of Si (1.9 and 2.4 wt%) were deposited on highly cleaned glass substrate by radio frequency (DC/RF) magnetron sputtering. The morphological and structural investigations have been performed by atomic force electron microscope (AFM) and X-ray diffraction (XRD). The X-ray photoelectron spectroscopy was employed to study the composition and the change in the chemical state of Si-doped ZnO thin films. The optical observations like transmittance, energy band gap, extinction coefficient, refractive index, dielectric loss of pure and Si-doped ZnO thin films have been calculated. The linear optical susceptibility, nonlinear refractive index, and nonlinear optical susceptibility were also studied by the spectroscopic approach rather than conventional Z-scan method. The energy gap of Si-doped ZnO thin films was found to increase as compared to pure ZnO thin films. The crystallinity of the ZnO thin films was effected by the Si doping. The O1s spectra in pure and Si-doped ZnO revealed the bound between O-2 and Zn+2 ions and reduction in the surface oxygen with the Si doping. The chemical state analysis of Si 2p showed the conversation of Si to SiOx and SiO2. The increase in the first-order linear optical susceptibility χ (1) and third-order nonlinear optical susceptibility χ (3) was observed with the Si doping. The nonlinear studies gave some details about the applications of metal oxides in nonlinear optical devices. In short, this study showed that Si doping through sputtering has effected on the structural, surface and optical properties of ZnO thin films which could be quite useful for advanced applications such as metal-oxide-based optical devices.

  7. Combined AFM nano-machining and reactive ion etching to fabricate high aspect ratio structures.

    Science.gov (United States)

    Peng, Ping; Shi, Tielin; Liao, Guanglan; Tang, Zirong

    2010-11-01

    In this paper, a new combined method of sub-micron high aspect ratio structure fabrication is developed which can be used for production of nano imprint template. The process includes atomic force microscope (AFM) scratch nano-machining and reactive ion etching (RIE) fabrication. First, 40 nm aluminum film was deposited on the silicon substrate by magnetron sputtering, and then sub-micron grooves were fabricated on the aluminum film by nano scratch using AFM diamond tip. As aluminum film is a good mask for etching silicon, high aspect ratio structures were finally fabricated by RIE process. The fabricated structures were studied by SEM, which shows that the grooves are about 400 nm in width and 5 microm in depth. To obtain sub-micron scale groove structures on the aluminum film, experiments of nanomachining on aluminum films under various machining conditions were conducted. The depths of the grooves fabricated using different scratch loads were also studied by the AFM. The result shows that the material properties of the film/substrate are elastic-plastic following nearly a bilinear law with isotropic strain hardening. Combined AFM nanomachining and RIE process provides a relative lower cost nano fabrication technique than traditional e-beam lithography, and it has a good prospect in nano imprint template fabrication.

  8. Magnetic properties of electroplated nano/microgranular NiFe thin films for rf application

    NARCIS (Netherlands)

    Zhuang, Y.; Vroubel, M.; Rejaei, B.; Burghartz, J.N.; Attenborough, K.

    2005-01-01

    A granular NiFe thin film with large in-plane magnetic anisotropy and high ferromagnetic-resonance frequency developed for radio-frequency integrated circuit (IC) applications is presented. During the deposition, three-dimensional (3D) growth occurs, yielding NiFe grains (ϕ ∼ 1.0 μm). Nanonuclei (ϕ

  9. Focused ion beam nano-structuring of $Al_2O_3$ dielectric layers for photonic applications

    NARCIS (Netherlands)

    Ay, Feridun; Bradley, Jonathan D.B.; Hopman, Wico C.L.; Gadgil, Vishwas J.; Ridder, de René M.; Wörhoff, Kerstin; Pollnau, Markus

    2007-01-01

    In order to enable full integration of active integrated optical components based on Si-technology, high quality micro- and nano-structuring processes aiming at the development of on-chip resonator structures are to be achieved. By optimizing focused ion beam milling parameters such as ion current,

  10. Key Techniques on Preparing High Aspect Ratio Micro and Nano Structures

    DEFF Research Database (Denmark)

    Jian, Zhao; Lianhe, Dong; Xiaoli, Zhu

    2016-01-01

    effectively. The mechanism of action between NaCl and HSQ was analyzed. The collapse and adhesion of resist structure due to the effect of gas-liquid interfacial capillary surface tension were suppressed by the CO2 supercritical drying method. Large-area dense nano-structures with the aspect ratio of 12...

  11. Micro/Nano-Structured Flexible Foils for Anti-Counterfeiting Purposes

    DEFF Research Database (Denmark)

    Okulova, Nastasia

    2016-01-01

    Up to date there have been found many ways of producing samples with functional nano-pattering, however for mass production of such samples the method of fabrication of the surface structure must be fast and cheap. A recently developed method suggests using extrusion coating of polymer materials...... in a roll-to roll process, where the functional micro-/nano- surface structures are imprinted directly onto the surface of a polymer foil. This new technology can both answer the requirement for being fast and cheap. The aim of this project is implementation of the technology for mass production...... has been demonstrated. The focus of this study lies on the reproduction of the previous results for nano- or micro-structures and implementation of this technology for mass production of such patterned foils for the use in packaging. An interesting application is production of holograms with build...

  12. Exploring electronic structure of one-atom thick polycrystalline graphene films: A nano angle resolved photoemission study

    Science.gov (United States)

    Avila, José; Razado, Ivy; Lorcy, Stéphane; Fleurier, Romain; Pichonat, Emmanuelle; Vignaud, Dominique; Wallart, Xavier; Asensio, María C.

    2013-01-01

    The ability to produce large, continuous and defect free films of graphene is presently a major challenge for multiple applications. Even though the scalability of graphene films is closely associated to a manifest polycrystalline character, only a few numbers of experiments have explored so far the electronic structure down to single graphene grains. Here we report a high resolution angle and lateral resolved photoelectron spectroscopy (nano-ARPES) study of one-atom thick graphene films on thin copper foils synthesized by chemical vapor deposition. Our results show the robustness of the Dirac relativistic-like electronic spectrum as a function of the size, shape and orientation of the single-crystal pristine grains in the graphene films investigated. Moreover, by mapping grain by grain the electronic dynamics of this unique Dirac system, we show that the single-grain gap-size is 80% smaller than the multi-grain gap recently reported by classical ARPES. PMID:23942471

  13. Structural, morphological and optical properties of PEDOT:PSS/QDs nano-composite films prepared by spin-casting

    Science.gov (United States)

    Najeeb, Mansoor Ani; Abdullah, Shahino Mah; Aziz, Fakhra; Ahmad, Zubair; Rafique, Saqib; Wageh, S.; Al-Ghamdi, Ahmed A.; Sulaiman, Khaulah; Touati, Farid; Shakoor, R. A.; Al-Thani, N. J.

    2016-09-01

    This paper describes the structural, morphological and optical properties of the nano-composite of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and quantum dots (QDs). The ZnSe and CdSe QDs have been synthesized, with the aid of Mercaptoacetic acid (MAA), by a colloidal method with an average size of ~5 to 7 nm. QDs have been embedded in PEDOT:PSS using a simple solution processing approach and has been deposited as thin films by spin coating technique. The QDs embedded PEDOT:PSS enhances the light absorption spectra of samples, prominently in terms of absorption intensity which may consequently improve sensitivity of the optoelectronic devices.

  14. Polymeric Thin Films for Organic Electronics: Properties and Adaptive Structures

    Directory of Open Access Journals (Sweden)

    Bruno Pignataro

    2013-03-01

    Full Text Available This review deals with the correlation between morphology, structure and performance of organic electronic devices including thin film transistors and solar cells. In particular, we report on solution processed devices going into the role of the 3D supramolecular organization in determining their electronic properties. A selection of case studies from recent literature are reviewed, relying on solution methods for organic thin-film deposition which allow fine control of the supramolecular aggregation of polymers confined at surfaces in nanoscopic layers. A special focus is given to issues exploiting morphological structures stemming from the intrinsic polymeric dynamic adaptation under non-equilibrium conditions.

  15. Anomalous Structure of Palladium-Capped Magnesium Thin Films

    Directory of Open Access Journals (Sweden)

    Kazuki Yoshimura

    2012-07-01

    Full Text Available Pd capped pure Mg thin film (50 nm thick was prepared by magnetron sputtering and its hydrogenation at room temperature has been investigated. After exposure to 4% hydrogen gas diluted by argon, the Pd/Mg thin films show drastic optical changes from the metallic state to the transparent state within five seconds by hydrogenation. Transmission electron microscope observation reveals that this sample has an anomalous structure; Mg grain is surrounded by Pd. This structure may be the reason why Pd/Mg films can be hydrogenated so quickly at room temperature.

  16. Condensation and Wetting Dynamics on Micro/Nano-Structured Surfaces

    Science.gov (United States)

    Olceroglu, Emre

    -condensable gases (NCGs), a novel characterization technique has been developed based on image tracking of droplet growth rates. The full-field dynamic characterization of superhydrophobic surfaces during condensation has been achieved using high-speed microscopy coupled with image-processing algorithms. This method is able to resolve heat fluxes as low as 20 W/m 2 and heat transfer coefficients of up to 1000 kW/m2, across an array of 1000's of microscale droplets simultaneously. Nanostructured surfaces with mixed wettability have been used to demonstrate delayed flooding during superhydrophobic condensation. These surfaces have been optimized and characterized using optical and electron microscopy, leading to the observation of self-organizing microscale droplets. The self-organization of small droplets effectively delays the onset of surface flooding, allowing the superhydrophobic surfaces to operate at higher supersaturations. Additionally, hierarchical surfaces have been fabricated and characterized showing enhanced droplet growth rates as compared to existing models. This enhancement has been shown to be derived from the presence of small feeder droplets nucleating within the microscale unit cells of the hierarchical surfaces. Based on the experimental observations, a mechanistic model for growth rates has been developed for superhydrophobic hierarchical surfaces. While superhydrophobic surfaces exhibit high heat transfer rates they are inherently unstable due to the necessity to maintain a non-wetted state in a condensing environment. As an alternative condensation surface, a novel design is introduced here using ambiphilic structures to promote the formation of a thin continuous liquid film across the surface which can still provide the benefits of superhydrophobic condensation. Preliminary results show that the ambiphilic structures restrain the film thickness, thus maintaining a low thermal resistance while simultaneously maximizing the liquid-vapor interface available for

  17. Stability of magnetic nano-structures with respect to shape modifications

    Science.gov (United States)

    Blachowicz, T.; Ehrmann, A.

    2016-08-01

    Magnetic nano-structures can be used for various applications. Examinations of nano-structured systems often aim at decreasing pattern sizes due to their possible utilization in data storage media, in order to enhance the possible information density in a given area. This scaling process, however, is limited by the resolution of the lithography process which is used to produce the nano-particles. Thus the influence of shape modifications on the magnetic properties is important to be examined, especially the correlation between small form changes and magnetization reversal processes or coercive fields. In a recent project, square nanoparticles from permalloy were simulated using Magpar. Simulations were performed for the ideal geometric shape used in the lithography process, for the realistic shape of the produced nano-particles as obtained by SEM, and for intermediate steps between these extreme shapes. This study allows for estimation of the reliability of magnetic properties of nano-structures with respect to shape modifications in the lithography process.

  18. Co-Assembled Supported Catalysts: Synthesis of Nano-Structured Supported Catalysts with Hierarchic Pores through Combined Flow and Radiation Induced Co-Assembled Nano-Reactors

    OpenAIRE

    Galip Akay

    2016-01-01

    A novel generic method of silica supported catalyst system generation from a fluid state is presented. The technique is based on the combined flow and radiation (such as microwave, thermal or UV) induced co-assembly of the support and catalyst precursors forming nano-reactors, followed by catalyst precursor decomposition. The transformation from the precursor to supported catalyst oxide state can be controlled from a few seconds to several minutes. The resulting nano-structured micro-porous s...

  19. Nano-bio-sensing

    CERN Document Server

    Carrara, Sandro

    2011-01-01

    This book examines state-of-the-art applications of nano-bio-sensing. It brings together researchers from nano-electronics and bio-technology, providing multidisciplinary content from nano-structures fabrication to bio-sensing applications.

  20. Overview of the Characteristics of Micro- and Nano-Structured Surface Plasmon Resonance Sensors

    Directory of Open Access Journals (Sweden)

    Byoungho Lee

    2011-01-01

    Full Text Available The performance of bio-chemical sensing devices has been greatly improved by the development of surface plasmon resonance (SPR based sensors. Advancements in micro- and nano-fabrication technologies have led to a variety of structures in SPR sensing systems being proposed. In this review, SPR sensors (from typical Kretschmann prism configurations to fiber sensor schemes with micro- or nano-structures for local light field enhancement, extraordinary optical transmission, interference of surface plasmon waves, plasmonic cavities, etc. are discussed. We summarize and compare their performances and present guidelines for the design of SPR sensors.

  1. Modifications in Structural, Electrical, Electronic and Mechanical Properties of Titanium Thin Films under different Gas Plasmas

    Science.gov (United States)

    Singh, Omveer; Dahiya, Raj P.; Malik, Hitendra K.

    2015-09-01

    In the recent past, Titanium thin films can be grown over different substrates such as silicon, glass and quartz by using versatile deposition techniques DC, RF sputtering, electronic beam and thermal evaporation etc. The grown films are then exposed in different gas environments for individual application. It has been found that Titanium nitride exhibits good chemical stability, mechanical and electrical properties. To investigate these properties in titanium nitride thin films, we have developed a new approach hot cathode arc discharge plasma system. By using this technique, we can measure plasma and nitriding parameters independently. In the present work, we have investigated gases mixture (Nitrogen, Argon and Hydrogen) effect on the structural, mechanical, electrical and electronic properties in plasma system. We have used 100% N2, 50% N2 + 50% Ar and 50% N2 + 50% H2 gases ratio for plasma nitriding. Structural and electronic structure properties are measured from X-ray diffractions (XRD) and X-ray photoelectron spectroscopy (XPS) respectively. The surface morphology of these films were measured using Atomic Force Microscopy (AFM) and the nano-indentation mode is used to find out the hardness of the samples. Government of India.

  2. Buffer layer for thin film structures

    Science.gov (United States)

    Foltyn, Stephen R.; Jia, Quanxi; Arendt, Paul N.; Wang, Haiyan

    2006-10-31

    A composite structure including a base substrate and a layer of a mixture of strontium titanate and strontium ruthenate is provided. A superconducting article can include a composite structure including an outermost layer of magnesium oxide, a buffer layer of strontium titanate or a mixture of strontium titanate and strontium ruthenate and a top-layer of a superconducting material such as YBCO upon the buffer layer.

  3. Performance of Nano-Submicron-Stripe Pd Thin-Film Temperature Sensors

    Science.gov (United States)

    Huo, Xiaoye; Xu, Jingjing; Wang, Zhenhai; Yang, Fan; Xu, Shengyong

    2016-07-01

    Dozens of small dual-beam thin-film temperature sensors with a total width down to 430 nm were fabricated and tested. The sensors were all made from 90-nm-thick Pd thin films, where the width of the narrow stripes was 70-100 nm and that of the wide ones was 210-800 nm. Two different calibration methods showed consistent and repeatable sensitivities of 0.7-1.2 μV/K for the sensors, confirming that the sensitivity mainly depended on the width configuration of each sensor. By integrating arrays of such sensors on a practical testing platform using hybrid e-beam lithography and photolithography techniques, we demonstrated that these sensors were capable of detecting a weak surface temperature difference of 0.1-0.2 K at microscale, and they could be scaled up as built-in temperature sensors in many practical devices.

  4. Performance of Nano-Submicron-Stripe Pd Thin-Film Temperature Sensors.

    Science.gov (United States)

    Huo, Xiaoye; Xu, Jingjing; Wang, Zhenhai; Yang, Fan; Xu, Shengyong

    2016-12-01

    Dozens of small dual-beam thin-film temperature sensors with a total width down to 430 nm were fabricated and tested. The sensors were all made from 90-nm-thick Pd thin films, where the width of the narrow stripes was 70-100 nm and that of the wide ones was 210-800 nm. Two different calibration methods showed consistent and repeatable sensitivities of 0.7-1.2 μV/K for the sensors, confirming that the sensitivity mainly depended on the width configuration of each sensor. By integrating arrays of such sensors on a practical testing platform using hybrid e-beam lithography and photolithography techniques, we demonstrated that these sensors were capable of detecting a weak surface temperature difference of 0.1-0.2 K at microscale, and they could be scaled up as built-in temperature sensors in many practical devices.

  5. Relationship between nano-scale deformation of coal structure and metamorphic-deformed environments

    Institute of Scientific and Technical Information of China (English)

    JU Yiwen; JIANG Bo; HOU Quanlin; WANG Guiliang

    2005-01-01

    There is a more consanguineous relation between nano-scale deformation of coal structure and metamorphic-deformed environment. In different metamorphic-deformed environments, deformation in the coal structure can occur not only at micro-scale, but also at nano-scale, and even leads to the change of molecular structure and nano-scale pore (<100 nm) structure. The latter is the main space absorbing coalbed methane. Through X-ray diffraction (XRD) and liquid-nitrogen absorption methods, the characteristics of macromolecular and nano-scale pore structures of coals in different metamorphic-deformed environments and deformational series of coals have been studied. By combining with high-resolution transmission electron microcopy (HRTEM), the macromolecular and nano-scale pore structures are also directly observed. These results demonstrate that the stacking Lc of the macromolecular BSU in tectonic coals increases quickly from the metamorphic-deformed environment of low rank coals to that of high rank coals. For different deformed tectonic coals, in the same metamorphic-deformed environment, the difference of Lc is obvious. These changes reflect chiefly the difference of different temperature and stress effect of nano-scale deformation in tectonic coals. The factor of temperature plays a greater role in the increase of macromolecular structure parameters Lc, the influence of stress factor is also important. With the stress strengthening, Lc shows an increasing trend, and La /Lc shows a decreasing trend. Therefore, Lc and La /Lc can be used as the indicator of nano-scale deformation degree of tectonic coals. With increasing temperature and pressure, especially oriented stress, the orientation of molecular structure becomes stronger, and ordering degree of C-nets and the arrangement of BSU are obviously enhanced. For the deformation of nano-scale pore structure, in the same metamorphic-deformed environment, along with the strengthening of stress, the ratio of mesopores to

  6. Structuring of DLC:Ag nanocomposite thin films employing plasma chemical etching and ion sputtering

    Science.gov (United States)

    Tamulevičius, Tomas; Tamulevičienė, Asta; Virganavičius, Dainius; Vasiliauskas, Andrius; Kopustinskas, Vitoldas; Meškinis, Šarūnas; Tamulevičius, Sigitas

    2014-12-01

    We analyze structuring effects of diamond like carbon based silver nanocomposite (DLC:Ag) thin films by CF4/O2 plasma chemical etching and Ar+ sputtering. DLC:Ag films were deposited employing unbalanced reactive magnetron sputtering of silver target with Ar+ in C2H2 gas atmosphere. Films with different silver content (0.6-12.9 at.%) were analyzed. The films (as deposited and exposed to plasma chemical etching) were characterized employing scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS), optical microscopy, ultraviolet-visible light (UV-VIS) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. After deposition, the films were plasma chemically etched in CF4/O2 mixture plasma for 2-6 min. It is shown that optical properties of thin films and silver nano particle size distribution can be tailored during deposition changing the magnetron current and C2H2/Ar ratio or during following plasma chemical etching. The plasma etching enabled to reveal the silver filler particle size distribution and to control silver content on the surface that was found to be dependent on Ostwald ripening process of silver nano-clusters. Employing contact lithography and 4 μm period mask in photoresist or aluminum the films were patterned employing CF4/O2 mixture plasma chemical etching, direct Ar+ sputtering or combined etching processes. It is shown that different processing recipes result in different final grating structures. Selective carbon etching in CF4/O2 gas mixture with photoresist mask revealed micrometer range lines of silver nanoparticles, while Ar+ sputtering and combined processing employing aluminum mask resulted in nanocomposite material (DLC:Ag) micropatterns.

  7. Hydrogen irradiation on TiO{sub 2} nano-thin films

    Energy Technology Data Exchange (ETDEWEB)

    Heidari, Sh.; Mohammadizadeh, M.R. [University of Tehran, Superconductivity Research Laboratory (SRL), Department of Physics, Tehran (Iran, Islamic Republic of); Mahjour-Shafiei, M. [University of Tehran, Department of Physics, Tehran (Iran, Islamic Republic of); Larijani, M.M.; Malek, M. [Science and Technology Research Institute, Agricultural, Medical and Industrial Research School, Karaj (Iran, Islamic Republic of)

    2015-10-15

    Titanium dioxide thin films were coated on soda-lime glass substrates using spray pyrolysis method with a thickness of 152 ± 10 nm. The films were irradiated with hydrogen ions at room temperature at various beam energies and fluences. Optimized incident beam energy and beam fluence were obtained to improve photocatalytic and hydrophilicity properties of TiO{sub 2} thin films by narrowing the band gap. Samples were characterized by scanning electron microscopy to study the surface morphology and by UV-Vis absorption spectroscopy to measure the band gap. The optical band gap of H-doped anatase TiO{sub 2} thin films irradiated with hydrogen beam with energies of 2 and 4 keV and a fluence of 10{sup 15} ions/cm{sup 2} was narrowed from 3.34 eV (before irradiation) to 3.04 and 2.92 eV (after irradiation), respectively. The irradiated sample with energy of 4 keV with a fluence of 10{sup 15} ions/cm{sup 2} has the best improvement. This is attributed to the contraction of the band gap and to the increase in surface active site. Furthermore, it was observed that photocatalytic and hydrophilicity properties of this sample were improved, as well. (orig.)

  8. Modeling and simulation of electronic structure, material interface and random doping in nano electronic devices

    Science.gov (United States)

    Chen, Duan; Wei, Guo-Wei

    2010-01-01

    The miniaturization of nano-scale electronic devices, such as metal oxide semiconductor field effect transistors (MOSFETs), has given rise to a pressing demand in the new theoretical understanding and practical tactic for dealing with quantum mechanical effects in integrated circuits. Modeling and simulation of this class of problems have emerged as an important topic in applied and computational mathematics. This work presents mathematical models and computational algorithms for the simulation of nano-scale MOSFETs. We introduce a unified two-scale energy functional to describe the electrons and the continuum electrostatic potential of the nano-electronic device. This framework enables us to put microscopic and macroscopic descriptions in an equal footing at nano scale. By optimization of the energy functional, we derive consistently-coupled Poisson-Kohn-Sham equations. Additionally, layered structures are crucial to the electrostatic and transport properties of nano transistors. A material interface model is proposed for more accurate description of the electrostatics governed by the Poisson equation. Finally, a new individual dopant model that utilizes the Dirac delta function is proposed to understand the random doping effect in nano electronic devices. Two mathematical algorithms, the matched interface and boundary (MIB) method and the Dirichlet-to-Neumann mapping (DNM) technique, are introduced to improve the computational efficiency of nano-device simulations. Electronic structures are computed via subband decomposition and the transport properties, such as the I-V curves and electron density, are evaluated via the non-equilibrium Green's functions (NEGF) formalism. Two distinct device configurations, a double-gate MOSFET and a four-gate MOSFET, are considered in our three-dimensional numerical simulations. For these devices, the current fluctuation and voltage threshold lowering effect induced by the discrete dopant model are explored. Numerical convergence

  9. Modeling and simulation of electronic structure, material interface and random doping in nano-electronic devices

    Science.gov (United States)

    Chen, Duan; Wei, Guo-Wei

    2010-06-01

    The miniaturization of nano-scale electronic devices, such as metal oxide semiconductor field effect transistors (MOSFETs), has given rise to a pressing demand in the new theoretical understanding and practical tactic for dealing with quantum mechanical effects in integrated circuits. Modeling and simulation of this class of problems have emerged as an important topic in applied and computational mathematics. This work presents mathematical models and computational algorithms for the simulation of nano-scale MOSFETs. We introduce a unified two-scale energy functional to describe the electrons and the continuum electrostatic potential of the nano-electronic device. This framework enables us to put microscopic and macroscopic descriptions in an equal footing at nano-scale. By optimization of the energy functional, we derive consistently coupled Poisson-Kohn-Sham equations. Additionally, layered structures are crucial to the electrostatic and transport properties of nano-transistors. A material interface model is proposed for more accurate description of the electrostatics governed by the Poisson equation. Finally, a new individual dopant model that utilizes the Dirac delta function is proposed to understand the random doping effect in nano-electronic devices. Two mathematical algorithms, the matched interface and boundary (MIB) method and the Dirichlet-to-Neumann mapping (DNM) technique, are introduced to improve the computational efficiency of nano-device simulations. Electronic structures are computed via subband decomposition and the transport properties, such as the I- V curves and electron density, are evaluated via the non-equilibrium Green's functions (NEGF) formalism. Two distinct device configurations, a double-gate MOSFET and a four-gate MOSFET, are considered in our three-dimensional numerical simulations. For these devices, the current fluctuation and voltage threshold lowering effect induced by the discrete dopant model are explored. Numerical

  10. Synthesis, optical properties and growth mechanism of MnO nano structures

    Science.gov (United States)

    Pandey, B. K.; Shahi, A. K.; Gopal, R.

    2013-10-01

    Manganese oxide (MnO) colloidal nanoparticles have been successfully synthesized by pulse laser ablation in double distilled water. Nd: YAG laser with focused output operating at different pulse energies (20, 30, 40, 50 mJ/pulse) was used for ablation. Synthesized MnO nano crystal phase and structure were confirmed by X-ray diffraction and SAED pattern. Optical properties of as synthesized MnO nano colloidal solution were studied by UV-vis absorption spectroscopy. Optical particle size and band gap of as synthesized MnO colloidal nanoparticles were calculated. Particle shape and size were determined by TEM/SEM image. It is observed that MnO nano colloidal particles assembled to make different structures after aging in the liquid media. Aspect ratio has been calculated from SEM picture. MnO nanoparticles show weak antiferromagnetic behavior at room temperature as measured by VSM. A typical mechanism has been proposed for the formation of different nanostructures.

  11. Synthesis, optical properties and growth mechanism of MnO nano structures

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, B.K., E-mail: bishnu.pandey750@gmail.com; Shahi, A.K.; Gopal, R., E-mail: profrgopal@gmail.com

    2013-10-15

    Manganese oxide (MnO) colloidal nanoparticles have been successfully synthesized by pulse laser ablation in double distilled water. Nd: YAG laser with focused output operating at different pulse energies (20, 30, 40, 50 mJ/pulse) was used for ablation. Synthesized MnO nano crystal phase and structure were confirmed by X-ray diffraction and SAED pattern. Optical properties of as synthesized MnO nano colloidal solution were studied by UV–vis absorption spectroscopy. Optical particle size and band gap of as synthesized MnO colloidal nanoparticles were calculated. Particle shape and size were determined by TEM/SEM image. It is observed that MnO nano colloidal particles assembled to make different structures after aging in the liquid media. Aspect ratio has been calculated from SEM picture. MnO nanoparticles show weak antiferromagnetic behavior at room temperature as measured by VSM. A typical mechanism has been proposed for the formation of different nanostructures.

  12. Advanced Structural Characterization of Organic Thin Films

    DEFF Research Database (Denmark)

    Gu, Yun

    In this thesis, the structural characterizations of three organic film systems are described. Several X-ray based techniques have been utilized for the characterizations for different research goals. The structures of N,N',N-trioctyltriazatriangulenium (Oct3-TATA+) salts have been investigated...... of small molecule and polymer layers is indicated by Flory- Huggins theory for the triisopropylsilylethynl pentacene (TIPS-PEN) and polystyrene blend films. In order to investigate the phase separated layers in the ink-jet printed films, we propose a method to measure diraction Bragg peaks by X...

  13. Advanced Structural Characterization of Organic Thin Films

    DEFF Research Database (Denmark)

    Gu, Yun

    In this thesis, the structural characterizations of three organic film systems are described. Several X-ray based techniques have been utilized for the characterizations for different research goals. The structures of N,N',N-trioctyltriazatriangulenium (Oct3-TATA+) salts have been investigated...... of small molecule and polymer layers is indicated by Flory- Huggins theory for the triisopropylsilylethynl pentacene (TIPS-PEN) and polystyrene blend films. In order to investigate the phase separated layers in the ink-jet printed films, we propose a method to measure diraction Bragg peaks by X...

  14. Understanding the Unique Electronic Properties of Nano Structures Using Photoemission Theory.

    Science.gov (United States)

    Kwon, Soonnam; Choi, Won Kook

    2015-12-04

    Newly emerging experimental techniques such as nano-ARPES are expected to provide an opportunity to measure the electronic properties of nano-materials directly. However, the interpretation of the spectra is not simple because it must consider quantum mechanical effects related to the measurement process itself. Here, we demonstrate a novel approach that can overcome this problem by using an adequate simulation to corroborate the experimental results. Ab initio calculation on arbitrarily-shaped or chemically ornamented nano-structures is elaborately correlated to photoemission theory. This correlation can be directly exploited to interpret the experimental results. To test this method, a direct comparison was made between the calculation results and experimental results on highly-oriented pyrolytic graphite (HOPG). As a general extension, the unique electronic structures of nano-sized graphene oxide and features from the experimental result of black phosphorous (BP) are disclosed for the first time as supportive evidence of the usefulness of this method. This work pioneers an approach to intuitive and practical understanding of the electronic properties of nano-materials.

  15. Synthesis, Characterization And Optoelectrical Properties of Cd Doped ZnO Poly Crystalline Nano Thin Films Deposited by Successive Ionic Layer Adsorption and Reaction (SILAR) Method

    Science.gov (United States)

    Bindal, Nitin; Sharma, Manisha; Kumar, H.; Sharma, S.; Upadhaya, S. C.

    2011-12-01

    Cadmium doped zinc oxide polycrystalline nano thin films were deposited on microscopic glass substrates following a modified chemical bath technique called Successive Ionic Layer Adsorption and Reaction (SILAR). Cadmium doping was found to increase the film grown rate. The X-ray diffraction pattern showed that films have polycrystalline nature. The SEM image revealed growth of large crystallites perpendicular to the substrates. The optical transmittance spectra indicate that these thin films have the direct energy band gap. The resistivity of these films decreased with increase in the temperature for all compositions, which confirmed the semiconducting nature of films.

  16. Femtosecond laser surface structuring and oxidation of chromium thin coatings: Black chromium

    Energy Technology Data Exchange (ETDEWEB)

    Kotsedi, L., E-mail: Kotsedi@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Mthunzi, P. [National Laser Centre, Council for Scientific and Industrial Research, 0001 Pretoria (South Africa); Muller, T.F.G. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Julies, B. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Manikandan, E. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Ramponi, R. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa)

    2014-12-01

    Highlights: • Oxidation of the chromium thin film to chromium oxide by femtosecond laser with a fundamental wavelength of 1064 nm. • Solar absorber from chromium oxide that low percentage reflectance. • Femtosecond laser oxidation, with a de-focused laser. • Chromium oxide formation by femtosecond laser in normal ambient. - Abstract: In view of their potential applications as selective solar absorbers, chromium coatings on float glass substrates were nano/micro structured by femtosecond laser in air. Raman and X-rays diffraction investigations confirmed the formation of an ultra-porous α-Cr{sub 2}O{sub 3} layer at the surface; higher is the input laser power, enhanced is the crystallinity of the α-Cr{sub 2}O{sub 3} layer. The α-Cr{sub 2}O{sub 3} layer with the Cr underneath it in addition to the photo-induced porosity acted as a classical ceramic–metal nano-composite making the reflectance to decrease significantly within the spectral range of 190–1100 nm. The average reflectance decreased from 70 to 2%.

  17. Solar absorptance of copper–cobalt oxide thin film coatings with nano-size, grain-like morphology: Optimization and synchrotron radiation XPS studies

    Energy Technology Data Exchange (ETDEWEB)

    Amri, Amun [School of Engineering and Energy, Murdoch University, Murdoch, 6150 WA (Australia); Department of Chemical Engineering, Riau University, Pekanbaru (Indonesia); Duan, XiaoFei [School of Chemistry, The University of Melbourne, VIC 3010 (Australia); Yin, Chun-Yang, E-mail: c.yin@murdoch.edu.au [School of Chemical and Mathematical Sciences, Murdoch University, Murdoch, 6150 WA (Australia); Jiang, Zhong-Tao, E-mail: z.jiang@murdoch.edu.au [School of Engineering and Energy, Murdoch University, Murdoch, 6150 WA (Australia); Rahman, M. Mahbubur; Pryor, Trevor [School of Engineering and Energy, Murdoch University, Murdoch, 6150 WA (Australia)

    2013-06-15

    Copper–cobalt oxides thin films had been successfully coated on reflective aluminium substrates via a facile sol–gel dip-coating method for solar absorptance study. The optimum absorptance in the range of solar radiation is needed for further optimum design of this material for selective solar absorber application. Field emission scanning electron microscopy was used to characterize the surface morphology of the coating whereby nano-size, grain-like morphology was observed. Synchrotron radiation X-ray photoelectron spectroscopy was employed to analyze the electronic structure of the coated surface showing that the (i) oxygen consisted of lattice, surface and subsurface oxygen, (ii) copper consisted of octahedral and tetrahedral Cu{sup +}, as well as octahedral and paramagnetic Cu{sup 2+} oxidation states, and (iii) cobalt consisted of tetrahedral and paramagnetic Co(II), octahedral Co(III) as well as mixed Co(II,III) oxidation states. In order to optimize the solar absorptance of the coatings, relevant parameters such as concentrations of cobalt and copper, copper/cobalt concentration ratios and dip-speed were investigated. The optimal coating with α = 83.4% was produced using 0.25 M copper acetate and 0.25 M cobalt chloride (Cu/Co ratio = 1) with dip-speed 120 mm/min (four cycles). The operational simplicity of the dip-coating system indicated that it could be extended for coating of other mixed metal oxides as well.

  18. Thin NbN film structures on SOI for SNSPD

    Energy Technology Data Exchange (ETDEWEB)

    Il' in, Konstantin; Kurz, Stephan; Henrich, Dagmar; Hofherr, Matthias; Siegel, Michael [IMS, KIT, Karlsruhe (Germany); Semenov, Alexei; Huebers, Heinz-Wilhelm [DLR, Berlin (Germany)

    2012-07-01

    Superconducting Nanowire Single-Photon Detectors (SNSPD) made from ultra-thin NbN films on sapphire demonstrate almost 100% intrinsic detection efficiency (DE). However the system DE values is less than 10% mostly limited by a very low absorptance of NbN films thinner than 5 nm. Integration of SNSPD in Si photonic circuit is a promising way to overcome this problem. We present results on optimization of technology of thin NbN film nanostructures on SOI (Silicon on Insulator) substrate used in Si photonics technology. Superconducting and normal state properties of these structures important for SNSPD development are presented and discussed.

  19. Structural and electrical properties of TiO2 thin films

    Science.gov (United States)

    Rao, M. C.; Ravindranadh, K.; Shekhawat, M. S.

    2016-05-01

    Titanium dioxide (TiO2) is traditionally the most widely used white pigment due to its high refractive index. Titanium dioxide (TiO2) is traditionally the most widely used white pigment due to its high refractive index. TiO2 has received considerable attention and it has been used for optical coatings, photo-catalysis agents, gas sensors and solar cells. In this work, nano-structured TiO2 thin films were grown by pulsed laser deposition (PLD) technique on glass substrates. The prepared thin films were annealed from 400-600 °C in air for a period of 2 hours. Effect of annealing on the structural and electrical properties was studied. X-ray diffraction pattern exhibits peaks correspond to tetragonal anatase phase of TiO2 and the evaluated average crystallite size of the prepared materials are in the range of 16 to 30 nm. Electrical properties of the prepared samples are analyzed.

  20. Structure and optical properties of CdS:O thin films

    Energy Technology Data Exchange (ETDEWEB)

    Asaba, Ryo; Wakita, Kazuki [Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology, Chiba (Japan); Kitano, Atsushi; Shim, YongGu [Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka (Japan); Mamedov, Nazim; Bayramov, Ayaz; Huseynov, Emil; Hasanov, Ilham [Institute of Physics, Azerbaijan National Academy of Science, Baku (Azerbaijan)

    2013-08-15

    We have studied structure and optical properties of CdS:O thin films deposited on soda lime glass substrates by rf magnetron sputtering in the atmosphere of oxygen/argon gases. According to X-ray diffraction and confocal Raman scattering data, the films deposited under oxygen partial pressure below 3% show crystalline structure of CdS. On the other hand, X-ray diffraction, confocal Raman scattering, TEM (transmission electron microscopy) and XPS (X-ray photoelectron spectroscopy) data are indicative of amorphization, nano-crystallization, and inclusion of CdO{sub 2} in CdS:O thin films obtained under oxygen partial pressure of 5%. The last films have shown significantly increased transmittance in a spectral range above the energy gap of CdS. The origin of this transmittance is discussed by taking into account redistribution of electronic density-of-states in amorphous phase, quantum size effect and contribution of CdO{sub 2}. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Nano-vanadium oxide thin films in mixed phase for microbolometer applications

    Energy Technology Data Exchange (ETDEWEB)

    Subrahmanyam, A; Bharat Kumar Reddy, Y [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Nagendra, C L [LEOS, ISRO, Peenya Industrial Estate, Bangalore 560060 (India)], E-mail: manu@iitm.ac.in

    2008-10-07

    Among the several phases of vanadium oxide, mixed phases of VO{sub 2} and V{sub 2}O{sub 5} are preferred for uncooled micro-bolometers with low noise. The aim of this investigation is to achieve mixed phase VO{sub 2} and V{sub 2}O{sub 5} thin films with nanometre grain sizes and high temperature coefficient of resistance (TCR). Since the phase depends upon the oxygen reactivity, these vanadium oxide thin films are prepared by reactive electron beam evaporation at different oxygen flow rates and substrate temperatures. The mixed phases have been evaluated through x-ray diffraction and x-ray photo emission studies. The temperature dependence of resistance has shown that the films grown at 473 K with 2.8 x 10{sup -5} mbar chamber pressure of oxygen (VO{sub 2} : V{sub 2}O{sub 5} ratio of 36 : 64) have the highest TCR of -3.2 K{sup -1} with a reasonable low resistance (120 {omega}/square)

  2. Light enhancements in nano-structured solar cells

    OpenAIRE

    Pastorelli, Francesco

    2013-01-01

    In this century some of our main issues are energy shortage and pollution. This work will briefly describe these problems, proposing a plan of action combining energy saving and different sustainable energy sources. Within different types of renewable energy sources, solar energy is the most abundant one. To make solar energy a more sustainable and cost effective technology we focus on enhancing the optical characteristics of thin film solar cells. In this category, organic solar cells are go...

  3. Influence of contamination on resin bond strength to nano-structured alumina-coated zirconia ceramic.

    Science.gov (United States)

    Zhang, Shanchuan; Kocjan, Andraz; Lehmann, Frank; Kosmac, Tomaz; Kern, Matthias

    2010-08-01

    The purpose of this study was to evaluate the influence of contamination and subsequent cleaning on the bond strength and durability of an adhesive resin to nano-structured alumina-coated zirconia ceramic. Zirconia ceramic disks were coated with nano-structured alumina, utilizing the hydrolysis of aluminum nitride powder. After immersion in saliva or the use of a silicone disclosing agent, specimens were cleaned with phosphoric acid etching or with tap water rinsing only. Uncontaminated specimens served as controls. Plexiglas tubes filled with composite resin were bonded with a phosphate monomer [10-methacryloxydecyl-dihydrogenphosphate (MDP)]-containing resin (Panavia 21). Subgroups of eight specimens each were stored in distilled water at 37 degrees C, either for 3 d without thermal cycling (TC) or for 150 d with 37,500 thermal cycles from 5 to 55 degrees C. The tensile bond strength (TBS) was determined using a universal testing machine at a crosshead speed of 2 mm min(-1). The topography of the debonded surface was scrutinized for fractographic features, utilizing both optical and scanning electron microscopy. The TBS to uncontaminated nano-structured alumina-coated zirconia ceramic was durable, while contamination significantly reduced the TBS. Phosphoric acid cleaning was effective in removal of saliva contamination from the coated bonding surface but was not effective in removal of the silicone disclosing agent. Nano-structured alumina coating improves resin bonding to zirconia ceramic and eliminates the need for air-abrasion before bonding.

  4. Cellulose and collagen derived micro-nano structured scaffolds for bone tissue engineering.

    Science.gov (United States)

    Aravamudhan, Aja; Ramos, Daisy M; Nip, Jonathan; Harmon, Matthew D; James, Roshan; Deng, Meng; Laurencin, Cato T; Yu, Xiaojun; Kumbar, Sangamesh G

    2013-04-01

    Scaffold based bone tissue engineering (BTE) has made great progress in regenerating lost bone tissue. Materials of natural and synthetic origin have been used for scaffold fabrication. Scaffolds derived from natural polymers offer greater bioactivity and biocompatibility with mammalian tissues to favor tissue healing, due to their similarity to native extracellular matrix (ECM) components. Often it is a challenge to fabricate natural polymer based scaffolds for BTE applications without compromising their bioactivity, while maintaining adequate mechanical properties. In this work, we report the fabrication and characterization of cellulose and collagen based micro-nano structured scaffolds using human osteoblasts (HOB) for BTE applications. These porous micro-nano structured scaffolds (average pore diameter 190 +/- 10 microm) exhibited mechanical properties in the mid range of human trabecular bone (compressive modulus 266.75 +/- 33.22 MPa and strength 12.15 3 +/- 2.23 MPa). These scaffolds supported the greater adhesion and phenotype maintenance of cultured HOB as reflected by higher levels of osteogenic enzyme alkaline phosphatase and mineral deposition compared to control polyester micro-nano structured scaffolds of identical pore properties. These natural polymer based micro-nano structured scaffolds may serve as alternatives to polyester based scaffolds for BTE applications.

  5. Focused ion beam nano-structuring of Bragg gratings in $Al_2O_3$ channel waveguides

    NARCIS (Netherlands)

    Ay, Feridun; Uranga, Amaia; Bradley, Jonathan D.B.; Wörhoff, Kerstin; Ridder, de René M.; Pollnau, Markus; Ridder, de R.M.; Ay, F.; Kauppinen, L.J.

    2008-01-01

    We report our recent results on an optimization study of focused ion beam (FIB) nano-structuring of Bragg gratings in $Al_2O_3$ channel waveguides. By optimizing FIB milling parameters such as ion current, dwell time, loop repetitions, scanning strategy, and applying a top metal layer for reducing c

  6. Nano-Structured Gratings for Improved Light Absorption Efficiency in Solar Cells

    Directory of Open Access Journals (Sweden)

    Farzaneh Fadakar Masouleh

    2016-09-01

    Full Text Available Due to the rising power demand and substantial interest in acquiring green energy from sunlight, there has been rapid development in the science and technology of photovoltaics (PV in the last few decades. Furthermore, the synergy of the fields of metrology and fabrication has paved the way to acquire improved light collecting ability for solar cells. Based on recent studies, the performance of solar cell can improve due to the application of subwavelength nano-structures which results in smaller reflection losses and better light manipulation and/or trapping at subwavelength scale. In this paper, we propose a numerical optimization technique to analyze the reflection losses on an optimized GaAs-based solar cell which is covered with nano-structured features from the same material. Using the finite difference time domain (FDTD method, we have designed, modelled, and analyzed the performance of three different arrangements of periodic nano-structures with different pitches and heights. The simulated results confirmed that different geometries of nano-structures behave uniquely towards the impinging light.

  7. Towards the understanding of structure formation and dynamics in bio-nano systems

    DEFF Research Database (Denmark)

    Yakubovich, Alexander V.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2008-01-01

    This paper gives an overview of a number of key structure formation processes involving the well known biomolecular and nano objects such as fullerenes, nanotubes, polypeptides, proteins and DNA molecules. We formulate the problems, describe the main experimental observations and theoretical adva...

  8. CHARACTERIZATION OF NANO-STRUCTURES IN MATERIALS BY TRANSMISSION ELECTRON MICROSCOPY

    OpenAIRE

    Tomokiyo, Y.

    2008-01-01

    We will introduce the usefulness of convergent beam electron diffraction (CBED) in nano-characterization of materials: (1) Determination of local lattice strain in Si, (2) Determination of polarity of GaN of wurtzite structure, (3) Measurement of local oxygen concentration of the high Tc superconductor YBa2Cu3Oy. Keywords: convergent beam electron diffraction

  9. Structural and Optical Properties of Nanoscale Galinobisuitite Thin Films

    Directory of Open Access Journals (Sweden)

    Omar H. Abd-Elkader

    2014-01-01

    Full Text Available Galinobisuitite thin films of (Bi2S3(PbS were prepared using the chemical bath deposition technique (CBD. Thin films were prepared by a modified chemical deposition process by allowing the triethanolamine (TEA complex of Bi3+ and Pb2+ to react with S2− ions, which are released slowly by the dissociation of the thiourea (TU solution. The films are polycrystalline and the average crystallite size is 35 nm. The composition of the films was measured using the atomic absorption spectroscopy (AAS technique. The films are very adherent to the substrates. The crystal structure of Galinobisuitite thin films was calculated by using the X-ray diffraction (XRD technique. The surface morphology and roughness of the films were studied using scanning electron microscopes (SEM, transmission electron microscopes (TEM and stylus profilers respectively. The optical band gaps of the films were estimated from optical measurements.

  10. Fabrication of micro/nano hierarchical structures with analysis on the surface mechanics

    Science.gov (United States)

    Jheng, Yu-Sheng; Lee, Yeeu-Chang

    2016-10-01

    Biomimicry refers to the imitation of mechanisms and features found in living creatures using artificial methods. This study used optical lithography, colloidal lithography, and dry etching to mimic the micro/nano hierarchical structures covering the soles of gecko feet. We measured the static contact angle and contact angle hysteresis to reveal the behavior of liquid drops on the hierarchical structures. Pulling tests were also performed to measure the resistance of movement between the hierarchical structures and a testing plate. Our results reveal that hierarchical structures at the micro-/nano-scale are considerably hydrophobic, they provide good flow characteristics, and they generate more contact force than do surfaces with micro-scale cylindrical structures.

  11. Characterizing the nano and micro structure of concrete to improve its durability

    KAUST Repository

    Monteiro, P.J.M.

    2009-09-01

    New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images of ice inside cement paste and cracking caused by the alkali-silica reaction (ASR) enables three-dimensional structural identification. The potential of neutron diffraction to determine reactive aggregates by measuring their residual strains and preferred orientation is studied. Results of experiments using these tools are shown on this paper. © 2009 Elsevier Ltd. All rights reserved.

  12. Self-assembled dual-sided hemispherical nano-dimple-structured broadband antireflection coatings

    Science.gov (United States)

    Lin, Cheng-Yen; Lin, Kun-Yi; Tsai, Hui-Ping; He, Yi-Xuan; Yang, Hongta

    2016-11-01

    A non-lithography-based approach is developed in this study for assembling monolayer close-packed hemispherical nano-dimple arrays on both sides of a PET film by a scalable Langmuir-Blodgett technology. The resulting gratings greatly suppress specular reflection and therefore enhance specular transmission for a broad range of visible wavelengths, resulting from a gradual change in the effective refractive index at air/PET interface. The experimental results reveal that the antireflection properties of the as-fabricated coatings are affected by the size of the nano-dimples. Moreover, both optical performances of single-sided and dual-sided nano-dimple-structured coatings have been investigated in this study.

  13. Comparative study: The effects of solvent on the morphology, optical and structural features of regioregular poly(3-hexylthiophene):fullerene thin films

    CSIR Research Space (South Africa)

    Motaung, DE

    2010-01-01

    Full Text Available : The effects of solvent on the morphology, optical and structural features of regioregular poly(3-hexylthiophene): fullerene thin films David E. Motaung1, 2, Gerald F. Malgas1,*, Christopher J. Arendse2, and Dirk Knoesen2 1National Centre for Nano... solar cells, morphology * Corresponding Author: Dr. Gerald Malgas, Tel: (+27) 012 841 3972, Fax: (+27) 012 841 2229, Email: gmalgas@csir.co.za 2 1. INTRODUCTION In the last decade, solution...

  14. Nano Indentation Inspection of the Mechanical Properties of Gold Nitride Thin Films

    Directory of Open Access Journals (Sweden)

    Armen Verdyan

    2007-10-01

    Full Text Available The morphology and the local mechanical properties of gold nitride thin films were studied by atomic force microscope (AFM. Gold nitride films were deposited for the first time on silicon substrate without any buffer layer at room temperature by reactive pulsed laser ablation deposition (RPLD. The films were fabricated on (100 Si wafers by RPLD technique in which KrF excimer laser was used to ablate a gold target in N2 atmosphere (0.1 GPa-100 Pa and ambient temperature. Scanning electron microscopy (SEM and atomic force microscopy inspections showed that the films were flat plane with rms roughness in the range of 35.1 nm-3.6 nm, depending on the deposition pressure. Rutherford backscattering spectrometry (RBS and energy dispersion spectroscopy (EDS used to detect the nitrogen concentration in the films, have revealed a composition close to Au3N. The film

  15. Tunable Gas Permeability of Polymer-Clay Nano Brick Wall Thin Film Assemblies

    Science.gov (United States)

    Gamboa, Daniel; Priolo, Morgan; Grunlan, Jaime

    2010-03-01

    Thin films of anionic natural montmorrilonite (MMT) clay and cationic polyethylenimine (PEI) have been produced by alternately dipping a plastic substrate into dilute aqueous mixtures containing each ingredient. After 40 polymer-clay layers have been deposited, the resulting transparent film exhibits an oxygen transmission rate (OTR) below 0.35 cm^3/m^2 . day when the pH of PEI solution is 10. This low permeability is due to a brick wall nanostructure comprised of completely exfoliated clay bricks in polymeric mortar. This brick wall creates an extremely tortuous path at thicknesses below 250 nm and clay concentration above 80 wt%. A 70-bilayer PEI-MMT assembly has an undetectable OTR (packaging and foil replacement for food.

  16. Nano Indentation Inspection of the Mechanical Properties of Gold Nitride Thin Films

    Directory of Open Access Journals (Sweden)

    Armen Verdyan

    2007-10-01

    Full Text Available The morphology and the local mechanical properties of gold nitride thin films were studied by atomic force microscope (AFM. Gold nitride films were deposited for the first time on silicon substrate without any buffer layer at room temperature by reactive pulsed laser ablation deposition (RPLD. The films were fabricated on (100 Si wafers by RPLD technique in which KrF excimer laser was used to ablate a gold target in N2 atmosphere (0.1 GPa-100 Pa and ambient temperature. Scanning electron microscopy (SEM and atomic force microscopy inspections showed that the films were flat plane with rms roughness in the range of 35.1 nm-3.6 nm, depending on the deposition pressure. Rutherford backscattering spectrometry (RBS and energy dispersion spectroscopy (EDS used to detect the nitrogen concentration in the films, have revealed a composition close to Au3N. The film

  17. On the influence of residual stress on nano-mechanical characterization of thin coatings.

    Science.gov (United States)

    Sebastiani, M; Bemporad, E; Carassiti, F

    2011-10-01

    In the present paper, the effect of residual stress on the mechanical behavior of thin hard coatings has been investigated by a new methodology based on the combined use of focused ion beam (FIB) micro-machining techniques and nanoindentation testing. Surface elastic residual stress were determined by nanoindentation testing on Focused Ion Beam (FIB) milled micro-pillars. The average residual stress present in a 3.8 microm CAE-PVD TiN coating on WC-Co substrate was calculated by the comparison of two different sets of load-depth curves, the first one obtained at centre of stress relieved pillars, the second one on the undisturbed (residually stressed) surface. Results for stress measurement were in good agreement with the estimate obtained by XRD (sin2 psi method) analysis on the same sample, adopting the same elastic constants. In addition, nanoindentation on stress relieved pillars also allowed to perform a more accurate evaluation of elastic modulus and hardness of the coating. The effect of residual stress on crack propagation modes was quantitatively analyzed by high-load nanoindentation and application of energy methods for fracture toughness evaluation. It is found that compressive residual stress plays a relevant role in determining the fracture behavior and failure modes of the coating. Finally, Microstructural observations of the deformation mechanisms of the TiN coating were performed by TEM analysis on the cross section of the indentation, obtained by FIB lamella thinning. Results showed that plastic deformation at the nanoscale essentially occurs by formation of shear bands inside the columnar grains, independently of residual stress. A transition between intra-granular shear deformation and columnar grain sliding is also observed as a function of the applied load.

  18. Sensing characteristics of plasmonic structure based on transferring process of polystyrene nano-beads

    Science.gov (United States)

    Kim, Doo Gun; Hwang, Jeongwoo; Kim, Seon Hoon; Ki, Hyun Chul; Kim, Tae Un; Shin, Jae Cheol; Jeong, Dae-Cheol; Jeon, Seungwon; Kim, Hong-Seung; Choi, Young-Wan

    2016-04-01

    We analyzed and demonstrated the double layered metallic nano-structures using polystyrene lift-off process on the conventional surface plasmon resonance (SPR) sensor to enhance the sensitivity of an SPR surface. The double layered plasmonic structures are optimized using the three-dimensional finite-difference time-domain method for the width, thickness, and period of the polystyrene beads. The thickness of the metal film and the metallic nano-hole is 20 and 20 nm in the 305 nm wide nano-hole size, respectively. The double layered metallic nano-structures are fabricated with monolayer polystyrene beads of chloromethyl latex 4% w/v 0.4 μm. The sensitivities of the conventional SPR sensor and the double layered plasmonic sensor are obtained to 42.2 and 60 degree/RIU, respectively. The SPR devices are also applied to the lead ion sensor. The resonance shifts of SPR sensors with and without a poly(vinyl chloride) membrane are 1328 RU and 788 RU from 10-5 M to 10-2 M concentration, respectively.

  19. Anomalous behavior of B{sub 1g} mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Subodh K., E-mail: subodhkgtm@gmail.com, E-mail: fouran@gmail.com; Ojha, S.; Singh, Fouran, E-mail: subodhkgtm@gmail.com, E-mail: fouran@gmail.com [Material Science Group, Inter University Accelerator Centre, New Delhi -110067 (India); Gautam, Naina [Department of Electronic Science, University of Delhi South Campus, New Delhi - 110023 (India); Singh, R. G. [Department of Physics, Bhagini Nivedita College, Delhi University, Delhi– 110043 (India); Shukla, D. K. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India)

    2015-12-15

    The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO) thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO{sub 2} lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb{sup +5} in the TiO{sub 2} lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR) spectra of films with small size crystallites shows stiffening of about 4 cm{sup −1} for the E{sub g(1)} mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B{sub 1g} mode exhibits a large anomalous softening of 20 cm{sup −1} with asymmetrical broadening; which was not reported for the case of pure TiO{sub 2} crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb{sup 5+} doping induced reduction of Ti{sup 4+} ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS) and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

  20. Post annealing effects on the properties of sputtered nano-crystallite indium tin oxide thin films on flexible polyimide substrate

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi Gheidari, A.; Iraj, M.; Kazemzad, M.; Behafarid, F. [Materials and Energy Research Center (MERC), Tehran (Iran); Hadad Dabaghi, H. [Departmet of Chemistry, Islamic Azad University of Karaj, Karaj (Iran); Kalhor, D. [Department of Physics, Damghan University of Basic Sciences (Iran)

    2008-07-01

    Indium tin oxide (ITO) thin films were deposited onto flexible polyimide substrates using RF sputtering system at room temperature. The deposited films were then heat treated at different temperatures in air and vacuum atmospheres. The structural variations and as consequence the electro-optical characteristic variations of the films were systematically investigated as a function of post annealing temperature and atmosphere. The structure of the films was studied by means of XRD and SEM techniques and the electro-optical characteristics were measured by four point probe and spectrophotometer, respectively. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Nano- and micro-structured silicon for hybrid near-infrared photodetectors

    Science.gov (United States)

    Äńerek, V.; Głowacki, E. D.; Bednorz, M.; Demchyshyn, S.; Sariciftci, N. S.; Ivanda, M.

    2016-05-01

    Structuring surface and bulk of crystalline silicon on different length scales can significantly alter its properties and possibly improve the performance of opto-electronic devices and sensors based on silicon. Different dominant feature scales are responsible for modification of some of electronic and optical properties of silicon. Several easily reproducible chemical methods for facile structuring of silicon on nano and micro-scales, based on both electroless and anodic etching of silicon in hydrofluoric acid based etchants, and chemical anisotropic etching of silicon in basic environments, are presented. We show how successive micro and nano structuring creates hierarchical silicon surfaces, which can be used to simultaneously exploit the advantages of both structuring feature length scales. Finally, we demonstrate a large increase in photocurrent obtained from a hybrid structured silicon/organic near-infrared photodetector. Improved silicon/6,6'-dibromoindigo hybrid photodiodes were prepared by nano- and micro-structuring the silicon part of the heterojunction by wet chemical etching methods. Photocurrent and spectral responsivity were improved in comparison to planar diodes by up to two orders of magnitude by optimization of the silicon structuring process. We show that the improvement in photocurrent is not due to the increase in surface area or light trapping.

  2. Structural, optical, and transport properties of nanocrystalline bismuth telluride thin films treated with homogeneous electron beam irradiation and thermal annealing.

    Science.gov (United States)

    Takashiri, Masayuki; Asai, Yuki; Yamauchi, Kazuki

    2016-08-19

    We investigated the effects of homogeneous electron beam (EB) irradiation and thermal annealing treatments on the structural, optical, and transport properties of bismuth telluride thin films. Bismuth telluride thin films were prepared by an RF magnetron sputtering method at room temperature. After deposition, the films were treated with homogeneous EB irradiation, thermal annealing, or a combination of both the treatments (two-step treatment). We employed Williamson-Hall analysis for separating the strain contribution from the crystallite domain contribution in the x-ray diffraction data of the films. We found that strain was induced in the thin films by EB irradiation and was relieved by thermal annealing. The crystal orientation along c-axis was significantly enhanced by the two-step treatment. Scanning electron microscopy indicated the melting and aggregation of nano-sized grains on the film surface by the two-step treatment. Optical analysis indicated that the interband transition of all the thin films was possibly of the indirect type, and that thermal annealing and two-step treatment methods increased the band gap of the films due to relaxation of the strain. Thermoelectric performance was significantly improved by the two-step treatment. The power factor reached a value of 17.2 μW (cm(-1) K(-2)), approximately 10 times higher than that of the as-deposited thin films. We conclude that improving the crystal orientation and relaxing the strain resulted in enhanced thermoelectric performance.

  3. Structural, optical, and transport properties of nanocrystalline bismuth telluride thin films treated with homogeneous electron beam irradiation and thermal annealing

    Science.gov (United States)

    Takashiri, Masayuki; Asai, Yuki; Yamauchi, Kazuki

    2016-08-01

    We investigated the effects of homogeneous electron beam (EB) irradiation and thermal annealing treatments on the structural, optical, and transport properties of bismuth telluride thin films. Bismuth telluride thin films were prepared by an RF magnetron sputtering method at room temperature. After deposition, the films were treated with homogeneous EB irradiation, thermal annealing, or a combination of both the treatments (two-step treatment). We employed Williamson-Hall analysis for separating the strain contribution from the crystallite domain contribution in the x-ray diffraction data of the films. We found that strain was induced in the thin films by EB irradiation and was relieved by thermal annealing. The crystal orientation along c-axis was significantly enhanced by the two-step treatment. Scanning electron microscopy indicated the melting and aggregation of nano-sized grains on the film surface by the two-step treatment. Optical analysis indicated that the interband transition of all the thin films was possibly of the indirect type, and that thermal annealing and two-step treatment methods increased the band gap of the films due to relaxation of the strain. Thermoelectric performance was significantly improved by the two-step treatment. The power factor reached a value of 17.2 μW (cm-1 K-2), approximately 10 times higher than that of the as-deposited thin films. We conclude that improving the crystal orientation and relaxing the strain resulted in enhanced thermoelectric performance.

  4. Electron beam generation and structure of defects in carbon and boron nitride nano-tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zobelli, A

    2007-10-15

    The nature and role of defects is of primary importance to understand the physical properties of C and BN (boron nitride) single walled nano-tubes (SWNTs). Transmission electron microscopy (TEM) is a well known powerful tool to study the structure of defects in materials. However, in the case of SWNTs, the electron irradiation of the TEM may knock out atoms. This effect may alter the native structure of the tube, and has also been proposed as a potential tool for nano-engineering of nano-tubular structures. Here we develop a theoretical description of the irradiation mechanism. First, the anisotropy of the emission energy threshold is obtained via density functional based calculations. Then, we numerically derive the total Mott cross section for different emission sites of carbon and boron nitride nano-tubes with different chiralities. Using a dedicated STEM (Scanning Transmission Electron Microscope) microscope with experimental conditions optimised on the basis of derived cross-sections, we are able to control the generation of defects in nano-tubular systems. Either point or line defects can be obtained with a spatial resolution of a few nanometers. The structure, energetics and electronics of point and line defects in BN systems have been investigated. Stability of mono- and di- vacancy defects in hexagonal boron nitride layers is investigated, and their activation energies and reaction paths for diffusion have been derived using the nudged elastic band method (NEB) combined with density functional based techniques. We demonstrate that the appearance of extended linear defects under electron irradiation is more favorable than a random distribution of point defects and this is due to the existence of preferential sites for atom emission in the presence of pre-existing defects, rather than thermal vacancy nucleation and migration. (author)

  5. Characterization of nano-powder grown ultra-thin film p-CuO/n-Si hetero-junctions by employing vapour-liquid-solid method for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Sultana, Jenifar; Das, Anindita [Centre for Research in Nanoscience and Nanotechnology (CRNN), Kolkata 700098 (India); Das, Avishek [Department of Electronic Science, University of Calcutta, Kolkata 700009 (India); Saha, Nayan Ranjan [Department of Polymer Science and Technology, University of Calcutta, Kolkata 700009 (India); Karmakar, Anupam [Department of Electronic Science, University of Calcutta, Kolkata 700009 (India); Chattopadhyay, Sanatan, E-mail: scelc@caluniv.ac.in [Department of Electronic Science, University of Calcutta, Kolkata 700009 (India)

    2016-08-01

    In this work, the CuO nano-powder has been synthesized by employing chemical bath deposition technique for its subsequent use to grow ultrathin film (20 nm) of p-CuO on n-Si substrate for the fabrication of p-CuO/n-Si hetero-junction diodes. The thin CuO film has been grown by employing vapour-liquid-solid method. The crystalline structure and chemical phase of the film are characterized by employing field-emission scanning electron microscopy and X-ray diffraction studies. Chemical stoichiometry of the film has been confirmed by using energy dispersive X-ray spectroscopy. The potential for photovoltaic applications of such films is investigated by measuring the junction current-voltage characteristics and by extracting the relevant parameters such as open circuit photo-generated voltage, short circuit current density, fill-factor and energy conversion efficiency. - Highlights: • Synthesis of CuO nano-powder by CBD method • Growth of ultra-thin film of CuO by employing VLS method for the first time • Physical and electrical characterization of such films for photovoltaic applications • Estimation of energy conversion efficiency of the p-CuO/n-Si p-n junction solar cell.

  6. Improving electronic structure methods to predict nano-optoelectronics and nano-catalyst functions.

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Ida Marie B.; Marzari, Nicola (Massachusetts Institute of Technology); Shelnutt, John Allen; Kulik, Heather J. (Massachusetts Institute of Technology); Medforth, Craig John (University of New Mexico, Albuquerque, NM); Leung, Kevin

    2009-10-01

    This report focuses on quantum chemistry and ab initio molecular dynamics (AIMD) calculations applied to elucidate the mechanism of the multi-step, 2-electron, electrochemical reduction of the green house gas molecule carbon dioxide (CO{sub 2}) to carbon monoxide (CO) in aqueous media. When combined with H{sub 2} gas to form synthesis ('syn') gas, CO becomes a key precursor to methane, methanol, and other useful hydrocarbon products. To elucidate the mechanism of this reaction, we apply computational electrochemistry which is a fledgling, important area of basic science critical to energy storage. This report highlights several approaches, including the calculation of redox potentials, the explicit depiction of liquid water environments using AIMD, and free energy methods. While costly, these pioneering calculations reveal the key role of hydration- and protonation-stabilization of reaction intermediates, and may inform the design of CO{sub 2}-capture materials as well as its electrochemical reduction. In the course of this work, we have also dealt with the challenges of identifying and applying electronic structure methods which are sufficiently accurate to deal with transition metal ion complex-based catalyst. Such electronic structure methods are also pertinent to the accurate modeling of actinide materials and therefore to nuclear energy research. Our multi-pronged effort towards achieving this titular goal of the LDRD is discussed.

  7. Technology development of the nano-crystalline silicon thin film materials%纳米晶硅薄膜材料的技术发展

    Institute of Scientific and Technical Information of China (English)

    吴大维; 吴越侠; 唐志斌

    2012-01-01

    The recent development of the nano - crystalline silicon thin film material is reviewed in this paper. Some ideas is proposed to promote advances of the silicon thin film solar cells. In this paper, we make come discussions on the development of silicon thin film solar cells and predict the prospect of latest ones.%本文综述了硅基薄膜材料的发展历程;提出了一些促进硅基薄膜电池技术进步的思路;并对硅 基薄膜电池的发展进行了有益的探讨,对最新的硅基薄膜太阳能电池作了展望.

  8. Nano-structural and Nano-chemical analysis of dissimilar metal weld interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung Joon; Shin, Sang Hoon; Kim, Jong Jin; Jung, Ju Ang; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2012-05-15

    Dissimilar Metal Welds (DMWs) is generally applied to nuclear power plants for manufacturing and machining in structural components such as reactor pressure vessels and pressurizer nozzles. Alloy 152 is used frequently as filler metal in the manufacture of the DMW in light water reactors to join the low alloy steel pressure vessel nozzles and steam generator nozzles to nickel-based wrought alloy or austenitic stainless steel components. However, in recent years cracking phenomena has been observed in the welded joints. Concerns have been raised to the integrity and reliability in the joint transition zone due to the high susceptibility of the heat affected zone (HAZ) and the fusion boundary (FB) to stress corrosion cracking in combination with thermal aging. Since the material microstructure and chemical composition are key parameters affecting the stress corrosion cracking, improving the understanding of stress corrosion cracking at the FB region requires fundamental understanding of the unique microstructure of the FB region in DMW. Despite the potential degradation and consequent risk in the DMW, there is still a lack of the fundamental understanding of microstructure in the FB region, in particular the region containing unidentified band structures near the FB. The scale of the microstructure in modern metallic materials is becoming increasingly smaller. The 3-dimensional atom probe tomography (3D APT) has a truly quantitative analytical capability to characterize nanometer scale particles in metallic materials, thus its application to the microstructural analysis in multi-component metallic materials provides critical information on the mechanism of nanoscale microstructural evolution. The 3D APT is a microscope that allows the reconstruction of 3D 'atom maps'. These reconstructions can be interrogated and interpreted to determine the nanoscale chemistry of the material. Therefore, the current study is aiming at the establishment of detail procedure

  9. Self-organized structures in soft confined thin films

    Indian Academy of Sciences (India)

    Ashutosh Sharma

    2005-10-01

    We present a mini-review of our recent work on spontaneous, self-organized creation of mesostructures in soft materials like thin films of polymeric liquids and elastic solids. These very small scale, highly confined systems are inherently unstable and thus self-organize into ordered structures which can be exploited for MEMS, sensors, opto-electronic devices and a host of other nanotechnology applications. In particular, mesomechanics requires incorporation of intermolecular interactions and surface tension forces, which are usually inconsequential in classical macroscale mechanics. We point to some experiments and quasi-continuum simulations of self-organized structures in thin soft films which are germane not only to nanotechnology, but also to a spectrum of classical issues such as adhesion/debonding, wetting, coatings, tribology and membranes.

  10. Nano-structural and Nano-chemical analysis of dissimilar metal weld interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung Joon; Shin, Shang Hoon; Kim, Jong Jin; Jung, Ju Ang; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2011-10-15

    Dissimilar metal weld is generally applied to nuclear power plant for manufacturing and machining in structural components such as RPV and Pressurizer nozzles. Alloy 152 is used frequently as filler metal in the manufacture of dissimilar metal welds (DMWs) in light water reactors (LWR) to join the low alloy steel (LAS) pressure vessel nozzles and steam generator nozzles to nickel-based wrought alloy or austenitic stainless steel components. The thermal expansion coefficient of the alloy lies between those of ferrite steel and austenitic stainless steel, and it also significantly retards the carbon diffusion from the ferrite base metal to the weld metal. However, in recent years cracking phenomena have been observed in the welded joints. A concern has been raised about the integrity and reliability in the joint transition zone due to the high susceptibility of heat affected zone (HAZ) and fusion zone (FZ) to stress corrosion cracking (SCC). The dissimilar metal joints which were welded between Inconel 690, Ni-based alloy and A533B, low alloy steel with Inconel 152, filler metal were investigated. This study shows microstructural and chemical analysis between Inconel 152 and A533B by using optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), secondary ion mass spectrometry (SIMS) and 3 dimension atom probe (3D AP). In the root region, OM and SEM analysis show the microstructure which contains the interface of Inconel 152 and A533B near the rooter region. And it shows unidentified band structure which is formed along weld interface. AP and TEM/EDS analyses show the chemical gradient containing higher Fe but lower Mn, Ni and Cr than Inconel 152 and the unidentified band

  11. First Helical Structure in the Nano-world

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ Although a commonplace structure in nature, the helix remains a mystery to scientific researchers. In biology,the structure is important as DNA is helical and so does the substructure of many proteins. Since its discovery more than 50 years ago, the double helix has offered an important approach to interpret and make use of bio-organic structures. Yet, it is seldom to see a helical structure formed by inorganic crystalstate materials.

  12. Structural characterization of vacuum evaporated ZnSe thin films

    Indian Academy of Sciences (India)

    Pradip Kr Kalita; B K Sarma; H L Das

    2000-08-01

    Thermally evaporated ZnSe thin films deposited on glass substrates within substrate temperatures (s) at 303 K–623 K are of polycrystalline nature having f.c.c. zincblende structure. The most preferential orientation is along [111] direction for all deposited films together with other abundant planes [220] and [311]. The lattice parameter, grain size, average internal stress, microstrain, dislocation density and degree of preferred orientation in the film are calculated and correlated with s.

  13. Experimental study of ultra-thin films mechanical integrity by combined nanoindentation and nano-acoustic emission

    Science.gov (United States)

    Zhang, Zihou

    Advancement of interconnect technology has imposed significant challenge on interface characterization and reliability for blurred interfaces between layers. There is a need for material properties and these miniaturized length scales and assessment of reliability; including the intrinsic film fracture toughness and the interfacial fracture toughness. The nano-meter range of film thicknesses currently employed, impose significant challenges on evaluating these physical quantities and thereby impose significant challenge on the design cycle. In this study we attempted to use a combined nano-indentation and nano-acoustic emission to qualitatively and quantitatively characterize the failure modes in ultra-thin blanket films on Si substrates or stakes of different characteristics. We have performed and analyzed an exhaustive group of testes that cove many diverge combination of film-substrate combination, provided by both Intel and IBM. When the force-indentation depth curve shows excursion, a direct measure of the total energy release rate is estimated. The collected acoustic emission signal is then used to partition the total energy into two segments, one associated with the cohesive fracture toughness of the film and the other is for the adhesive fracture toughness of the interface. The acoustic emission signal is analyzed in both the time and frequency domain to achieve such energy division. In particular, the signal time domain analysis for signal skewness, time of arrival and total energy content are employed with the proper signal to noise ratio. In the frequency domain, an expansive group of acoustic emission signals are utilized to construct the details of the power spectral density. A bank of band-pass filters are designed to sort the individual signals to those associated with adhesive interlayer cracking, cohesive channel cracking, or other system induced noise. The attenuation time and the energy content within each spectral frequency were the key elements

  14. Synthesis of Ag-TiO2 composite nano thin film for antimicrobial application.

    Science.gov (United States)

    Yu, Binyu; Leung, Kar Man; Guo, Qiuquan; Lau, Woon Ming; Yang, Jun

    2011-03-18

    TiO2 photocatalysts have been found to kill cancer cells, bacteria and viruses under mild UV illumination, which offers numerous potential applications. On the other hand, Ag has long been proved as a good antibacterial material as well. The advantage of Ag-TiO2 nanocomposite is to expand the nanomaterial's antibacterial function to a broader range of working conditions. In this study neat TiO2 and Ag-TiO2 composite nanofilms were successfully prepared on silicon wafer via the sol-gel method by the spin-coating technique. The as-prepared composite Ag-TiO2 and TiO2 films with different silver content were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to determine the topologies, microstructures and chemical compositions, respectively. It was found that the silver nanoparticles were uniformly distributed and strongly attached to the mesoporous TiO2 matrix. The morphology of the composite film could be controlled by simply tuning the molar ratio of the silver nitrate aqueous solution. XPS results confirmed that the Ag was in the Ag(0) state. The antimicrobial effect of the synthesized nanofilms was carried out against gram-negative bacteria (Escherichia coli ATCC 29425) by using an 8 W UV lamp with a constant relative intensity of 0.6 mW cm(-2) and in the dark respectively. The synthesized Ag-TiO2 thin films showed enhanced bactericidal activities compared to the neat TiO2 nanofilm both in the dark and under UV illumination.

  15. Synthesis of Ag-TiO2 composite nano thin film for antimicrobial application

    Science.gov (United States)

    Yu, Binyu; Leung, Kar Man; Guo, Qiuquan; Lau, Woon Ming; Yang, Jun

    2011-03-01

    TiO2 photocatalysts have been found to kill cancer cells, bacteria and viruses under mild UV illumination, which offers numerous potential applications. On the other hand, Ag has long been proved as a good antibacterial material as well. The advantage of Ag-TiO2 nanocomposite is to expand the nanomaterial's antibacterial function to a broader range of working conditions. In this study neat TiO2 and Ag-TiO2 composite nanofilms were successfully prepared on silicon wafer via the sol-gel method by the spin-coating technique. The as-prepared composite Ag-TiO2 and TiO2 films with different silver content were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to determine the topologies, microstructures and chemical compositions, respectively. It was found that the silver nanoparticles were uniformly distributed and strongly attached to the mesoporous TiO2 matrix. The morphology of the composite film could be controlled by simply tuning the molar ratio of the silver nitrate aqueous solution. XPS results confirmed that the Ag was in the Ag0 state. The antimicrobial effect of the synthesized nanofilms was carried out against gram-negative bacteria (Escherichia coli ATCC 29425) by using an 8 W UV lamp with a constant relative intensity of 0.6 mW cm - 2 and in the dark respectively. The synthesized Ag-TiO2 thin films showed enhanced bactericidal activities compared to the neat TiO2 nanofilm both in the dark and under UV illumination.

  16. High-rate deposition of nano-crystalline silicon thin films on plastics

    Energy Technology Data Exchange (ETDEWEB)

    Marins, E.; Guduru, V.; Cerqueira, F.; Alpuim, P. [Centro de Fisica, Universidade do Minho, 4800-058 Guimaraes, 4710-057 Braga (Portugal); Ribeiro, M. [Centro de Nanotecnologia e Materiais Tecnicos, Funcionais e Inteligentes (CeNTI), 4760-034 Vila Nova de Famalicao (Portugal); Bouattour, A. [Institut fuer Physikalische Elektronik (ipe), Universitaet Stuttgart, 70569 Stuttgart (Germany)

    2011-03-15

    Nanocrystalline silicon (nc-Si:H) is commonly used in the bottom cell of tandem solar cells. With an indirect bandgap, nc-Si:H requires thicker ({proportional_to}1 {mu}m) films for efficient light harvesting than amorphous Si (a-Si:H) does. Therefore, thin-film high deposition rates are crucial for further cost reduction of highly efficient a-Si:H based photovoltaic technology. Plastic substrates allow for further cost reduction by enabling roll-to-roll inline deposition. In this work, high nc-Si:H deposition rates on plastic were achieved at low substrate temperature (150 C) by standard Radio-frequency (13.56 MHz) Plasma Enhanced Chemical Vapor Deposition. Focus was on the influence of deposition pressure, inter-electrode distance (1.2 cm) and high power coupled to the plasma, on the hydrogen-to-silane dilution ratios (HD) necessary to achieve the amorphous-to-nanocrystalline phase transition and on the resulting film deposition rate. For each pressure and rf-power, there is a value of HD for which the films start to exhibit a certain amount of crystalline fraction. For constant rf-power, this value increases with pressure. Within the parameter range studied the deposition rate was highest (0.38 nm/s) for nc-Si:H films deposited at 6 Torr, 700 mW/cm{sup 2} using HD of 98.5%. Decreasing the pressure to 3 Torr (1.5 Torr) and rf-power to 350 mW/cm{sup 2} using HD - 98.5% deposition rate is 0.12 nm/s (0.076 nm/s). Raman crystalline fraction of these films is 72, 62 and 53% for the 6, 3 and 1.5 Torr films, respectively (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Bioinspired Non-iridescent Structural Color from Polymer Blend Thin Films

    Science.gov (United States)

    Nallapaneni, Asritha; Shawkey, Matthew; Karim, Alamgir

    Colors exhibited in biological species are either due to natural pigments, sub-micron structural variation or both. Structural colors thus exhibited can be iridescent (ID) or non-iridescent (NID) in nature. NID colors originate due to interference and coherent scattering of light with quasi-ordered micro- and nano- structures. Specifically, in Eastern Bluebird (Sialia sialis) these nanostructures develop as a result of phase separation of β-keratin from cytoplasm present in cells. We replicate these structures via spinodal blend phase separation of PS-PMMA thin films. Colors of films vary from ultraviolet to blue. Scattering of UV-visible light from selectively leeched phase separated blends are studied in terms of varying domain spacing (200nm to 2 μm) of film. We control these parameters by tuning annealing time and temperature. Angle-resolved spectroscopy studies suggest that the films are weakly iridescent and scattering from phase-separated films is more diffused when compared to well-mixed films. This study offers solutions to several color-based application in paints and coatings industry.

  18. Spatial solitons in periodic semiconductor-dielectric nano-structures

    CERN Document Server

    Gorbach, A V

    2009-01-01

    A detailed analysis of the existence and stability of TE and TM nonlinear guided modes in one-dimensional sub-wavelength periodic semiconductor-dielectric structures is done using the full vector nonlinear Maxwell equations. Linear spectra for both light polarizations gradually transform towards those of a quasi-homogeneous medium with decreasing structure period. The properties of TE solitons change accordingly, so that for small enough periods, TE solitons stop feeling the presence of the structure. However TM sotitons are demonstrated to sustain inhomogeneous field distribution for any small period of the structure, developing strong intensity peaks inside dielectric slots. Qualitative transfomation in the structure of TM solitons occurs as the structure period is decreased, and is accompained by the change in their stability properties. This is linked to the corresponding qualitative changes in the linear modes structure, related to the Brewster condition.

  19. Picosecond laser induced periodic surface structure on copper thin films

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, Thi Trang Dai; Petit, Agnès; Semmar, Nadjib, E-mail: nadjib.semmar@univ-orleans.fr

    2014-05-01

    LIPSS (Laser Induced Periodic Surface Structure) formation on copper thin films induced by a picosecond laser beam (Nd:YAG laser at 266 nm, 42 ps and 10 Hz) was studied experimentally. Copper thin films were deposited on glass and silicon substrates by magnetron sputtering. The surface modifications of irradiated zones were analyzed by scanning electron microscopy. Two distinct types of LIPSS were identified with respect to the laser fluence (F), number of laser shots (N) and substrate material. Namely, with a number of laser shots (1000 < N < 10,000) and a fluence of (200 mJ/cm{sup 2} < F < 500 mJ/cm{sup 2}), Low Spatial Frequency LIPSS (LSFL with a spatial period of Λ ∼ 260 nm and an orientation perpendicular to polarization) and High Spatial Frequency LIPSS (HSFL with a spatial period of Λ ∼ 130 nm and an orientation parallel to the polarization) were observed. The regime of regular spikes formation was determined for N ≥ 1000. Moreover, the 2D-map of the relationship among LIPSS formation, laser fluence and number of laser shots on copper thin film with two different substrates was established. A physics interpretation of regular spikes and LIPSS formation on copper thin film induced by ps laser with overlapping multi-shots is proposed based on experimental data and the theory of Plateau-Rayleigh instability.

  20. Picosecond laser induced periodic surface structure on copper thin films

    Science.gov (United States)

    Huynh, Thi Trang Dai; Petit, Agnès; Semmar, Nadjib

    2014-05-01

    LIPSS (Laser Induced Periodic Surface Structure) formation on copper thin films induced by a picosecond laser beam (Nd:YAG laser at 266 nm, 42 ps and 10 Hz) was studied experimentally. Copper thin films were deposited on glass and silicon substrates by magnetron sputtering. The surface modifications of irradiated zones were analyzed by scanning electron microscopy. Two distinct types of LIPSS were identified with respect to the laser fluence (F), number of laser shots (N) and substrate material. Namely, with a number of laser shots (1000 LIPSS (LSFL with a spatial period of Λ ∼ 260 nm and an orientation perpendicular to polarization) and High Spatial Frequency LIPSS (HSFL with a spatial period of Λ ∼ 130 nm and an orientation parallel to the polarization) were observed. The regime of regular spikes formation was determined for N ≥ 1000. Moreover, the 2D-map of the relationship among LIPSS formation, laser fluence and number of laser shots on copper thin film with two different substrates was established. A physics interpretation of regular spikes and LIPSS formation on copper thin film induced by ps laser with overlapping multi-shots is proposed based on experimental data and the theory of Plateau-Rayleigh instability.

  1. Spun-wrapped aligned nanofiber (SWAN) lithography for fabrication of micro/nano-structures on 3D objects

    Science.gov (United States)

    Ye, Zhou; Nain, Amrinder S.; Behkam, Bahareh

    2016-06-01

    Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for fabrication of multiscale (nano to microscale) structures on 3D objects without restriction on substrate material and geometry. SWAN lithography combines precise deposition of polymeric nanofiber masks, in aligned single or multilayer configurations, with well-controlled solvent vapor treatment and etching processes to enable high throughput (>10-7 m2 s-1) and large-area fabrication of sub-50 nm to several micron features with high pattern fidelity. Using this technique, we demonstrate whole-surface nanopatterning of bulk and thin film surfaces of cubes, cylinders, and hyperbola-shaped objects that would be difficult, if not impossible to achieve with existing methods. We demonstrate that the fabricated feature size (b) scales with the fiber mask diameter (D) as b1.5 ~ D. This scaling law is in excellent agreement with theoretical predictions using the Johnson, Kendall, and Roberts (JKR) contact theory, thus providing a rational design framework for fabrication of systems and devices that require precisely designed multiscale features.Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for

  2. A study of angle dependent surface plasmon polaritons in nano-hole array structures

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnan, Shankar [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Lawson Health Research Institute, St. Joseph' s Health Care, London, Ontario N6A 4V2 (Canada); Najiminaini, Mohamadreza; Carson, Jeffrey J. L. [Lawson Health Research Institute, St. Joseph' s Health Care, London, Ontario N6A 4V2 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada)

    2016-07-21

    We report that the light-matter interaction in metallic nano-hole array structures possess a subwavelength hole radius and periodicity. The transmission coefficient for nano-hole array structures was measured for different angles of incidence of light. Each measured transmission spectrum had several peaks due to surface plasmon polaritons. A theory of the transmission coefficient was developed based on the quantum density matrix method. It was found that the location of the surface plasmon polariton and the heights of the spectral peaks were dependent on the angle of incidence of light. Good agreement was observed between the experimental and theoretical results. This property of these structures has opened up new possibilities for sensing applications.

  3. Study of micro and nano surface structures from UV irradiated urethane/urea elastomers.

    Science.gov (United States)

    Godinho, M H; Trindade, A C; Figueirinhas, J L; Melo, L V; Brogueira, P

    2007-02-01

    In this work we address new results obtained with a thin free standing flexible film (approximately 120 microm) of a urethane/urea copolymer related to the formation of micro and nano size structures [M.H. Godinho, A.C. Trindade, J.L. Figueirinhas, L.V. Melo, P. Brogueira, Synthetic Metals, 147(1-3), 209 (2004); M.H. Godinho, A.C. Trindade, J.L. Figueirinhas, L.V. Melo, P. Brogueira, Molecular Crystals and Liquid Crystals (2005)]. The copolymer was synthesized from a polypropylene oxide-based prepolymer with three isocyanate terminal groups (PU) and polybutadienediol (PBDO) with PBDO content of 40% wt. After casting and curing the film was cut into different samples and each exposed to UV radiation for different periods of time; 23, 25, 26, 31 and 49 h (lambda=254 nm) and later extracted with toluene and dried. The dried films were then studied by polarising optical microscopy (POM), small angle light scattering (SALS) and the surfaces exposed to UV radiation analyzed by means of atomic force microscopy (AFM). Before extraction with toluene a nanometer-flat surface, characterized by a mean roughness value Ra=0.59 nm, was obtained. Depending on exposure time to UV radiation and after extraction with toluene a corrugated surface, with features mum-sized in all axes, resulting in an increase of the overall mean roughness value to Ra=50.7 nm, starts to develop after 25 h of exposure time. This work gives evidence of the non-monotonous time behavior of the wrinkled surface growth that develops under the action of ultraviolet radiation. As the exposure time increases the free-standing films directly exposed surfaces show a decreasing density of the structures observed and an increasing characteristic peak-to-valley height. The peak-to-valley height measured for samples exposed for 23, 25, 26, 31 and 49 h, respectively 193, 383, 381, 1550 and 2039 nm and the corresponding mean roughness values are Ra=50.7 nm, 105.4, 116.8, 438.3 and 515.4 nm, respectively. Between 26 and

  4. Effect of Argon/Oxygen Flow Rate Ratios on DC Magnetron Sputtered Nano Crystalline Zirconium Titanate Thin Films

    Science.gov (United States)

    Rani, D. Jhansi; Kumar, A. GuruSampath; Sarmash, T. Sofi; Chandra Babu Naidu, K.; Maddaiah, M.; Rao, T. Subba

    2016-06-01

    High transmitting, non absorbent, nano crystalline zirconium titanate (ZT) thin films suitable for anti reflection coatings (ARC) were deposited on to glass substrates by direct current (DC) magnetron reactive sputtering technique, under distinct Argon to Oxygen (Ar/O2) gas flow rate ratios of 31/1, 30/2, 29/3 and 28/4, with a net gas flow (Ar + O2) of 32sccm, at an optimum substrate temperature of 250°C. The influence of the gas mixture ratio on the film properties has been investigated by employing x-ray diffraction (XRD), ultra violet visible (UV-vis) spectroscopy, atomic force microscopy (AFM), energy dispersive x-ray analysis (EDX) and four point probe methods. The films showed a predominant peak at 30.85° with (111) orientation. The crystallite size reduced from 22.94 nm to 13.5 nm and the surface roughness increased from 11.53 nm to 50.58 nm with increase in oxygen content respectively. The films deposited at 31/1 and 30/2 showed almost similar chemical composition. Increased oxygen content results an increase in electrical resistivity from 3.59 × 103 to 2.1 × 106 Ωm. The film deposited at Ar/O2 of 28/4 exhibited higher average optical transmittance of 91%, but its refractive index is higher than that of what is required for ARC. The films deposited at 31/1 and 30/2 of Ar/O2 possess higher transmittance (low absorbance) apart from suitable refractive index. Thus, these films are preferable candidates for ARC.

  5. Direct writing of large-area micro/nano-structural arrays on single crystalline germanium substrates using femtosecond lasers

    Science.gov (United States)

    Li, Lin; Wang, Jun

    2017-06-01

    A direct writing technique for fabricating micro/nano-structural arrays without using a multi-scanning process, multi-beam interference, or any assisted microlens arrays is reported. Various sub-wavelength micro/nano-structural arrays have been directly written on single crystalline germanium substrate surfaces using femtosecond laser pulses. The evolution of the multiscale surface morphology from periodic micro/nano-structures to V-shaped microgrooves has been achieved, and the relationship between array characteristics and laser polarization directions has been discussed. The self-organization model agrees well with the experimental results in this study.

  6. Fabrication and condensation characteristics of metallic superhydrophobic surface with hierarchical micro-nano structures

    Science.gov (United States)

    Chu, Fuqiang; Wu, Xiaomin

    2016-05-01

    Metallic superhydrophobic surfaces have various applications in aerospace, refrigeration and other engineering fields due to their excellent water repellent characteristics. This study considers a simple but widely applicable fabrication method using a two simultaneous chemical reactions method to prepare the acid-salt mixed solutions to process the metal surfaces with surface deposition and surface etching to construct hierarchical micro-nano structures on the surface and then modify the surface with low surface-energy materials. Al-based and Cu-based superhydrophobic surfaces were fabricated using this method. The Al-based superhydrophobic surface had a water contact angle of 164° with hierarchical micro-nano structures similar to the lotus leaves. The Cu-based surface had a water contact angle of 157° with moss-like hierarchical micro-nano structures. Droplet condensation experiments were also performed on these two superhydrophobic surfaces to investigate their condensation characteristics. The results show that the Al-based superhydrophobic surface has lower droplet density, higher droplet jumping probability, slower droplet growth rate and lower surface coverage due to the more structured hierarchical structures.

  7. Effect of Nano-Particle Addition on Grain Structure Evolution of Friction Stir-Processed Al 6061 During Postweld Annealing

    Science.gov (United States)

    Guo, Junfeng; Lee, Bing Yang; Du, Zhenglin; Bi, Guijun; Tan, Ming Jen; Wei, Jun

    2016-08-01

    The fabrication of nano-composites is challenging because uniform dispersion of nano-sized reinforcements in metallic substrate is difficult to achieve using powder metallurgy or liquid processing methods. In the present study, Al-based nano-composites reinforced with Al2O3 particles have been successfully fabricated using friction stir processing. The effects of nano-Al2O3 particle addition on grain structure evolution of friction stir-processed Al matrix during post-weld annealing were investigated. It was revealed that the pinning effect of Al2O3 particles retarded grain growth and completely prevented abnormal grain growth during postweld annealing at 470°C. However, abnormal grain growth can still occur when the composite material was annealed at 530°C. The mechanism involved in the grain structure evolution and the effect of nano-sized particle addition on the mechanical properties were discussed therein.

  8. Surface Structure of Thin Films of Multifunctional Ionizable Copolymers

    Science.gov (United States)

    Wickramasinghe, Anuradhi; Perahia, Dvora

    Phase segregation results in a rich variety of structures in co-polymers where interfacial forces often dominate the structure of thin films. Introduction of ionizable segments often drives the formation of compounded structures with multiple blocks residing at the interfaces. Here we probe thin films, 40-50nm, of an A-B-C-B-A co-polymer where C is a randomly sulfonated polystyrene with sulfonation fractions of 0, 26 and 52 mole %, B is poly (ethylene-r-propylene), and A is poly (t-butyl styrene) as the sulfonation level and temperature are varied using Neutron Reflectivity AFM, and surface tension measurements. As cast films form layers with both hydrophobic blocks dominating the solid and air interfaces and the ionizable block segregating to the center. Following annealing at 1700C, above Tg of styrene sulfonate, the films coarsen, with surface aggregation dominating the structure, though interfacial regions remain dominated by the hydrophobic segments. We show that in contrast to non-ionic co-polymers, formation of micelles dominated the structure of these ionic structured films. Supported in part by DOE Grant No. DE-SC007908.

  9. Design of periodic nano- and macro-scale textures for high-performance thin-film multi-junction solar cells

    Science.gov (United States)

    Krc, J.; Sever, M.; Kovacic, M.; Moulin, E.; Campa, A.; Lipovsek, B.; Steltenpool, M.; van Erven, A. J. M.; Haug, F.-J.; Ballif, C.; Topic, M.

    2016-06-01

    Surface textures in thin-film silicon multi-junction solar cells play an important role in gaining the photocurrent of the devices. In this paper, a design of the textures is carried out for the case of amorphous silicon/micro-crystalline silicon (a-Si:H/μc-Si:H) solar cells, employing advanced modelling to determine the textures for defect-free silicon layer growth and to increase the photocurrent. A model of non-conformal layer growth and a hybrid optical modelling approach are used to perform realistic 3D simulations of the structures. The hybrid optical modelling includes rigorous modelling based on the finite element method and geometrical optics models. This enables us to examine the surface texture scaling from nano- to macro-sized (several tens or hundreds of micrometers) texturisation features. First, selected random and periodic nanotextures are examined with respect to critical positions of defect-region formation in Si layers. We show that despite careful selection of a well-suited semi-ellipsoidal periodic texture for defect-free layer growth, defective regions in Si layers of a-Si:H/μc-Si:H cell cannot be avoided if the lateral and vertical dimensions of the nano features are optimised only for high gain in photocurrent. Macro features are favourable for defect-free layer growth, but do not render the photocurrent gains as achieved with light-scattering properties of the optimised nanotextures. Simulation results show that from the optical point of view the semi-ellipsoidal periodic nanotextures with lateral features smaller than 0.4 μm and vertical peak-to-peak heights around or above 0.3 μm are required to achieve a gain in short-circuit current of the top cell with respect to the state-of-the-art random texture (>16% increase), whereas lateral dimensions around 0.8 μm and heights around 0.6 μm lead to a >6% gain in short-circuit current of the bottom cell.

  10. Temperature-Driven Structural and Morphological Evolution of Zinc Oxide Nano-Coalesced Microstructures and Its Defect-Related Photoluminescence Properties.

    Science.gov (United States)

    Lim, Karkeng; Abdul Hamid, Muhammad Azmi; Shamsudin, Roslinda; Al-Hardan, N H; Mansor, Ishak; Chiu, Weesiong

    2016-04-20

    In this paper, we address the synthesis of nano-coalesced microstructured zinc oxide thin films via a simple thermal evaporation process. The role of synthesis temperature on the structural, morphological, and optical properties of the prepared zinc oxide samples was deeply investigated. The obtained photoluminescence and X-ray photoelectron spectroscopy outcomes will be used to discuss the surface structure defects of the prepared samples. The results indicated that the prepared samples are polycrystalline in nature, and the sample prepared at 700 °C revealed a tremendously c-axis oriented zinc oxide. The temperature-driven morphological evolution of the zinc oxide nano-coalesced microstructures was perceived, resulting in transformation of quasi-mountain chain-like to pyramidal textured zinc oxide with increasing the synthesis temperature. The results also impart that the sample prepared at 500 °C shows a higher percentage of the zinc interstitial and oxygen vacancies. Furthermore, the intensity of the photoluminescence emission in the ultraviolet region was enhanced as the heating temperature increased from 500 °C to 700 °C. Lastly, the growth mechanism of the zinc oxide nano-coalesced microstructures is discussed according to the reaction conditions.

  11. Microfabricated structures and devices featuring nanostructured titania thin films

    Science.gov (United States)

    Monkowski, Adam J.

    2007-05-01

    When titanium reacts with hydrogen peroxide at 80°C--100°C, a nanostructured titania (NST) thin film is formed on the titanium surface. This nanostructured film is particularly suited for integration with thin film and bulk microfabrication techniques. The ability to manufacture devices in a batch format is a principal advantage of microfabrication-based production. To reliably produce arrays of micro-patterned NST thin films on the wafer scale, a patterning guideline must be considered. The formation of NST relies on a re-deposition process; adequate ti-peroxo species must be generated and remain at the solid-solution interface. Numerical analysis of the characteristic transient diffusion behavior for various micro-patterns has been compared with experimental data to generate a criterion to guide the design of NST micro-patterns. Wafer scale arrays of NST micro gas-sensors have been fabricated using standard thin film techniques. Sensing elements are 20 mum on a side. High sensitivity to hydrogen is achieved by modification of the sensors with platinum nanoparticles. When exposed to a 10 mT partial pressure of hydrogen at 250°C, the functionalized devices exhibit more than one order of magnitude resistance decrease with a response time of approximately 7 sec. Titanium microstructures formed using the titanium ICP deep etch (TIDE) process have been integrated with NST films to produce an ordered nanostructure-microstructure composite (3D-NST). The process developed allows for the incorporation of a planar top surface, advantageous for bonding and sealing applications, in which the nanostructured thin film is formed only on feature sidewalls and floors. When titanium microstructures are spaced less than 1 mum apart, titania nanostructures bridge adjacent features. NST and 3D-NST structures have been assembled and tested in a dye-sensitized solar cell (DSSC) device. The NST film is approximately 900nm thick; this yielded a DSSC with an efficiency of 1.8%, similar

  12. The Dynamic Similitude Design Method of Thin Walled Structures and Experimental Validation

    Directory of Open Access Journals (Sweden)

    Zhong Luo

    2016-01-01

    Full Text Available For the applicability of dynamic similitude models of thin walled structures, such as engine blades, turbine discs, and cylindrical shells, the dynamic similitude design of typical thin walled structures is investigated. The governing equation of typical thin walled structures is firstly unified, which guides to establishing dynamic scaling laws of typical thin walled structures. Based on the governing equation, geometrically complete scaling law of the typical thin walled structure is derived. In order to determine accurate distorted scaling laws of typical thin walled structures, three principles are proposed and theoretically proved by combining the sensitivity analysis and governing equation. Taking the thin walled annular plate as an example, geometrically complete and distorted scaling laws can be obtained based on the principles of determining dynamic scaling laws. Furthermore, the previous five orders’ accurate distorted scaling laws of thin walled annular plates are presented and numerically validated. Finally, the effectiveness of the similitude design method is validated by experimental annular plates.

  13. Laser-assisted structuring and modification of LiCoO2 thin films

    Science.gov (United States)

    Kohler, R.; Proell, J.; Ulrich, S.; Trouillet, V.; Indris, S.; Przybylski, M.; Pfleging, W.

    2009-02-01

    The material development of improved lithium ion batteries will play an important role in future mobile applications and energy storage systems. Electrode materials made of nano-composited materials are expected to improve battery lifetime and will lead to an enhancement of lithium diffusion and thus improve battery capacity and cyclability. In this study, research was conducted to further improve the electrochemical properties of thin film cathodes by increasing the surface to volume ratio and thereby the lithium intercalation rate. Cathode materials were synthesised by r.f. magnetron sputtering of LiCoO2 targets in a pure argon plasma. LiCoO2 films 3 μm thick and with a grain size of 10 to 500 nm were deposited on silicon and stainless steel substrates. The deposition parameters (argon pressure, substrate bias) were varied to create stoichiometric films with controlled nano-crystalline texture and morphology. During laser-assisted surface treatment, cone-shaped periodic surface structures were produced. For this purpose high repetition excimer laser radiation at wavelengths of 193 nm and 248 nm and with short laser pulse widths (4-6 ns) were used. Structure sizes varied with laser and processing parameters, e.g. laser fluences, pulse number, wavelength and processing gas. Laser annealing in air or furnace annealing in a controlled argon/oxygen environment were then used to create the high temperature phase of LiCoO2 (HT-LiCoO2). The sputtered films were studied with Raman spectroscopy, x-ray photoelectron spectroscopy and x-ray diffraction to determine their stoichiometry and crystallinity before and after laser treatment. The development of HT-LiCoO2 and also the formation of a Co3O4 phase were discussed. By means of electrochemical cycling, the performance of the manufactured films was investigated.

  14. Pinning of superconducting vortices in MoGe/Au Thin nano-squares

    Science.gov (United States)

    Serrier-Garcia, Lise; Timmermans, Matias; Van de Vondel, Joris; Moshchalkov, Victor V.

    2017-02-01

    In this work, we report a scanning tunneling spectroscopy study of vortex patterns in mesoscopic superconducting squares and explore the impact of defects and corrugations inherently present in nanofabricated structures. We find that a hillock at the edge can function as an attractive or repulsive pinning center for vortices deforming the, theoretically predicted, symmetry-induced vortex configurations. In addition, we exploit the inherently present imperfections, creating metastable states, to visualize the dynamics of vortex penetration during magnetic field sweeps.

  15. The Transmission Modes and Losses of the Poled Nano-crystal and Polymer Composite PbTiO3/PEK-c Thin-film Waveguides

    Institute of Scientific and Technical Information of China (English)

    REN Quan; Yuk Tak Chow; YANG Xudong; LV Zenghai; YANG Hongliang; CHAN Hau Ping; CHU Pak Lim

    2007-01-01

    Composite thin films of PbTiO3 nano-crystals and high transparency polymer polyetherketone(PEK-c) for application of non-linear optical devices were prepared by spin coating. The size of PbTiO3 nano-crystals was estimated to be 30-40 nm using a transmission electron microscope. The refractive index and the mode propagation losses at 633 nm were measured using the prism coupling technique and improved photographic technique respectively. They were found to be 1.6545 and 2.00 dB cm-1 (fundamental mode),respectively. Moreover, it is observed that this loss is increased at higher mode indices.

  16. Self-assembled germanium nano-structures by laser-assisted oxidation

    Institute of Scientific and Technical Information of China (English)

    Huang Wei-Qi; Liu Shi-Rong

    2006-01-01

    The investigation on the oxidation behaviour of Si1-xGex; alloys (x=0.05, 0.15, and 0.25) is carried out. It is found for the first time that on the oxide film a germanium nano-cap with a thickness of 1.8ranging from 5.5 nm to 10 nm are formed by the low-temperature laser-assisted dry oxidation of Si1-xGex substrate. A new scanning method on the decline cross-section of the multiple-layer sample is adopted to measure the layer thickness and the composition. Some new peaks in photoluminescence (PL) spectra are discovered, which could be related to the nano-cap and the nano-particles of germanium. A suitable model and several new calculating formulae with the unrestricted Hartree-Fock-Roothaan (UHFR) method and quantum confinement analysis are proposed to interpret the PL spectra and the nano-structure mechanism in the oxide.

  17. Experiences in supporting the structured collection of cancer nanotechnology data using caNanoLab

    Directory of Open Access Journals (Sweden)

    Stephanie A. Morris

    2015-07-01

    Full Text Available The cancer Nanotechnology Laboratory (caNanoLab data portal is an online nanomaterial database that allows users to submit and retrieve information on well-characterized nanomaterials, including composition, in vitro and in vivo experimental characterizations, experimental protocols, and related publications. Initiated in 2006, caNanoLab serves as an established resource with an infrastructure supporting the structured collection of nanotechnology data to address the needs of the cancer biomedical and nanotechnology communities. The portal contains over 1,000 curated nanomaterial data records that are publicly accessible for review, comparison, and re-use, with the ultimate goal of accelerating the translation of nanotechnology-based cancer therapeutics, diagnostics, and imaging agents to the clinic. In this paper, we will discuss challenges associated with developing a nanomaterial database and recognized needs for nanotechnology data curation and sharing in the biomedical research community. We will also describe the latest version of caNanoLab, caNanoLab 2.0, which includes enhancements and new features to improve usability such as personalized views of data and enhanced search and navigation.

  18. Experiences in supporting the structured collection of cancer nanotechnology data using caNanoLab.

    Science.gov (United States)

    Morris, Stephanie A; Gaheen, Sharon; Lijowski, Michal; Heiskanen, Mervi; Klemm, Juli

    2015-01-01

    The cancer Nanotechnology Laboratory (caNanoLab) data portal is an online nanomaterial database that allows users to submit and retrieve information on well-characterized nanomaterials, including composition, in vitro and in vivo experimental characterizations, experimental protocols, and related publications. Initiated in 2006, caNanoLab serves as an established resource with an infrastructure supporting the structured collection of nanotechnology data to address the needs of the cancer biomedical and nanotechnology communities. The portal contains over 1,000 curated nanomaterial data records that are publicly accessible for review, comparison, and re-use, with the ultimate goal of accelerating the translation of nanotechnology-based cancer therapeutics, diagnostics, and imaging agents to the clinic. In this paper, we will discuss challenges associated with developing a nanomaterial database and recognized needs for nanotechnology data curation and sharing in the biomedical research community. We will also describe the latest version of caNanoLab, caNanoLab 2.0, which includes enhancements and new features to improve usability such as personalized views of data and enhanced search and navigation.

  19. Hinged Polysilicon Structures with Integrated CMOS Thin Film Transistors

    Science.gov (United States)

    Pister, Kristofer Stefan Josef

    Micro electromechanical systems (MEMS) have the potential to have a profound impact on both scientific research and commercial products. MEMS have proven to be a commercial success, finding application in such diverse environments as hospital operating rooms and automobile engines. One of the open research problems in MEMS is the fabrication of three dimensional structures using what is essentially a planar process. Several methods exist for making large vertical steps in silicon, but they offer only specific geometries and have limited resolution. The process described here is based on polysilicon surface micromachining, with the addition that micro hinges are built along with other structures. In this approach, polycrystalline silicon structural elements are fabricated in the plane of the wafer, and then rotated out of the plane of the wafer using hinged joints. Individual elements are then assembled together to form more complicated three dimensional structures with high detail in all dimensions. The assembly process has been automated to some degree by the inclusion of spring loaded locks which snap into place once a hinge has reached a critical angle. With these hinged structures and spring locks, thousands of structures can be rotated and locked into place simultaneously in the final step of fabrication. Several examples of hinged three dimensional structures are presented, including a hot wire anemometer, a frog-embryo dynamometer, and a parallel jaw gripper, all of which fit inside a 1 millimeter cube. In addition to the structural elements provided in the process, several electronic elements have been integrated as well. These elements include CMOS thin film transistors integrated directly in the polysilicon structural thin film, piezoresistive strain sensors for measuring force and deflection, and flexible micro ribbon cable which allows electrical wiring to be run between the substrate and the rotated structures.

  20. Tunable nano-wrinkling of chiral surfaces: Structure and diffraction optics

    Energy Technology Data Exchange (ETDEWEB)

    Rofouie, P.; Rey, A. D., E-mail: alejandro.rey@mail.mcgill.ca [Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 2B2 (Canada); Pasini, D. [Department of Mechanical Engineering, McGill University, 817 Sherbrook West, Montreal, Quebec H3A 0C3 (Canada)

    2015-09-21

    Periodic surface nano-wrinkling is found throughout biological liquid crystalline materials, such as collagen films, spider silk gland ducts, exoskeleton of beetles, and flower petals. These surface ultrastructures are responsible for structural colors observed in some beetles and plants that can dynamically respond to external conditions, such as humidity and temperature. In this paper, the formation of the surface undulations is investigated through the interaction of anisotropic interfacial tension, swelling through hydration, and capillarity at free surfaces. Focusing on the cellulosic cholesteric liquid crystal (CCLC) material model, the generalized shape equation for anisotropic interfaces using the Cahn-Hoffman capillarity vector and the Rapini-Papoular anchoring energy are applied to analyze periodic nano-wrinkling in plant-based plywood free surfaces with water-induced cholesteric pitch gradients. Scaling is used to derive the explicit relations between the undulations’ amplitude expressed as a function of the anchoring strength and the spatially varying pitch. The optical responses of the periodic nano-structured surfaces are studied through finite difference time domain simulations indicating that CCLC surfaces with spatially varying pitch reflect light in a wavelength higher than that of a CCLC’s surface with constant pitch. This structural color change is controlled by the pitch gradient through hydration. All these findings provide a foundation to understand structural color phenomena in nature and for the design of optical sensor devices.

  1. Optimization of thermoelectric properties for rough nano-ridge GaAs/AlAs superlattice structure

    Science.gov (United States)

    Wu, Chao-Wei; Wu, Yuh-Renn

    2016-11-01

    In this paper, optimizations of thermoelectric(TE) properties for the rough surface of the nano-ridge GaAs/AlAs superlattice(SL) structure are investigated. The nano-ridge featured with rough surface at both sides of the SL structure is introduced, where the modification of the phonon spatial confinement and phonon surface roughness scattering are taken into account. The elastic continuum model is employed to calculate the phonon dispersion relation and the related phonon group velocity. Reported experimental results with SL structures were used for verification of our model. The lattice thermal conductivity, electrical conductivity, Seebeck coefficient, and electronic thermal conductivity are calculated by Boltzmann transport equations and relaxation time approximation. Simulation results show that the nano-ridge SL structure with certain periodicity and phonon surface roughness scattering have strong influences on the TE properties. Highest ZT in our calculation is 1.285 at 300K and the ZT value of 3.04 is obtained at 1000K.

  2. Tunable nano-wrinkling of chiral surfaces: Structure and diffraction optics

    Science.gov (United States)

    Rofouie, P.; Pasini, D.; Rey, A. D.

    2015-09-01

    Periodic surface nano-wrinkling is found throughout biological liquid crystalline materials, such as collagen films, spider silk gland ducts, exoskeleton of beetles, and flower petals. These surface ultrastructures are responsible for structural colors observed in some beetles and plants that can dynamically respond to external conditions, such as humidity and temperature. In this paper, the formation of the surface undulations is investigated through the interaction of anisotropic interfacial tension, swelling through hydration, and capillarity at free surfaces. Focusing on the cellulosic cholesteric liquid crystal (CCLC) material model, the generalized shape equation for anisotropic interfaces using the Cahn-Hoffman capillarity vector and the Rapini-Papoular anchoring energy are applied to analyze periodic nano-wrinkling in plant-based plywood free surfaces with water-induced cholesteric pitch gradients. Scaling is used to derive the explicit relations between the undulations' amplitude expressed as a function of the anchoring strength and the spatially varying pitch. The optical responses of the periodic nano-structured surfaces are studied through finite difference time domain simulations indicating that CCLC surfaces with spatially varying pitch reflect light in a wavelength higher than that of a CCLC's surface with constant pitch. This structural color change is controlled by the pitch gradient through hydration. All these findings provide a foundation to understand structural color phenomena in nature and for the design of optical sensor devices.

  3. Fabrication of Nano-Micro Hybrid Structures by Replication and Surface Treatment of Nanowires

    Directory of Open Access Journals (Sweden)

    Yeonho Jeong

    2017-07-01

    Full Text Available Nanowire structures have attracted attention in various fields, since new characteristics could be acquired in minute regions. Especially, Anodic Aluminum Oxide (AAO is widely used in the fabrication of nanostructures, which has many nanosized pores and well-organized nano pattern. Using AAO as a template for replication, nanowires with a very high aspect ratio can be fabricated. Herein, we propose a facile method to fabricate a nano-micro hybrid structure using nanowires replicated from AAO, and surface treatment. A polymer resin was coated between Polyethylene terephthalate (PET and the AAO filter, roller pressed, and UV-cured. After the removal of aluminum by using NaOH solution, the nanowires aggregated to form a micropattern. The resulting structure was subjected to various surface treatments to investigate the surface behavior and wettability. As opposed to reported data, UV-ozone treatment can enhance surface hydrophobicity because the UV energy affects the nanowire surface, thus altering the shape of the aggregated nanowires. The hydrophobicity of the surface could be further improved by octadecyltrichlorosilane (OTS coating immediately after UV-ozone treatment. We thus demonstrated that the nano-micro hybrid structure could be formed in the middle of nanowire replication, and then, the shape and surface characteristics could be controlled by surface treatment.

  4. Aged nano-structured platinum based catalyst: effect of chemical treatment on adsorption and catalytic activity.

    Science.gov (United States)

    Shim, Wang Geun; Nahm, Seung Won; Park, Hyuk Ryeol; Yun, Hyung Sun; Seo, Seong Gyu; Kim, Sang Chai

    2011-02-01

    To examine the effect of chemical treatment on the adsorption and catalytic activity of nanostructured platinum based catalyst, the aged commercial Pt/AC catalyst was pretreated with sulfuric acid (H2SO4) and a cleaning agent (Hexane). Several reliable methods such as nitrogen adsorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and inductively coupled plasma (ICP) were employed to characterize the aged Pt/AC catalyst and its chemically pretreated Pt/AC catalysts. The catalytic and adsorption activities of nano-structured heterogeneous Pt/AC catalyst were investigated on the basis of toluene oxidation and adsorption isotherm data. In addition, the adsorption isotherms of toluene were used to calculate the adsorption energy distribution functions for the parent catalyst and its pre-treated nano-structured Pt/AC catalysts. It was found that sulfuric acid aqueous treatment can enhance the catalytic performance of aged Pt/AC catalyst toward catalytic oxidation of toluene. It was also shown that a comparative analysis of the energy distribution functions for nano-structured Pt/AC catalysts as well as the pore size distribution provides valuable information about their structural and energetic heterogeneity.

  5. Characterization of quasi-nano-sized TiCx-Ni-Fe thin composite sheet prepared by using self-propagating high-temperature synthesis reaction and electroforming

    Science.gov (United States)

    Choi, Yong

    2014-05-01

    Thin TiCx-Ni-Fe composites sheet was prepared by self-propagating high-temperature synthesis (SHS) and electroforming. The quasi-nano-sized titanium carbide particles were prepared by self-propagating high temperature synthesis (SHS) followed by mechanical milling and ultrasonic floating agitation for classifying particles. The composite sheet was fabricated by co-deposition of the classified titanium carbide particles in a modified Watts nickel bath containing iron chloride during nickel-iron electro-forming. Neutron diffraction showed that the non-stoichiometric number of titanium carbides formed by the SHS reaction were in the range of 0.68 to 0.97, which depended on the initial carbon sources. X-ray diffraction and electron probe micro-analysis revealed that co-deposition of the carbides in Ni-Fe bath during the electroforming process produced a thin TiCx-Ni-Fe composite sheet, in which quasi-nano-sized titanium carbides were embedded about 7 at.%. The average surface resistance of the thin composite sheet was 1.053 ohm/sq. The corrosion potential and rate of the composites in a 50% NaOH solution were -920.6 mVSHE and 8.4×10-6 Acm-2, respectively.

  6. Highly stable thin film transistors using multilayer channel structure

    KAUST Repository

    Nayak, Pradipta K.

    2015-03-09

    We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60°C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO2 layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO2 layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

  7. Natural evolution inspired design of light trapping structure in thin film organic solar cells

    Science.gov (United States)

    Wang, Chen; Yu, Shuangcheng; Chen, Wei; Sun, Cheng

    2013-09-01

    Light trapping has been developed to effectively enhance the efficiency of the thin film solar cell by extending the pathlength for light interacting with the active materials. Searching for optimal light trapping design requires a delicate balance among all the competing physical processes, including light refraction, reflection, and absorption. The existing design methods mainly depend on engineers' intuition to predefine the topology of the light-trapping structure. However, these methods are not capable of handling the topological variation in reaching the optimal design. In this work, a systematic approach based on Genetic Algorithm is introduced to design the scattering pattern for effective light trapping. Inspired by natural evolution, this method can gradually improve the performance of light trapping structure through iterative procedures, producing the most favorable structure with minimized reflection and substantial enhancement in light absorption. Both slot waveguide based solar cell and a more realistic organic solar with a scattering layer consisting of nano-scale patterned front layer is optimized to maximize absorption by strongly coupling incident sun light into the localized photonic modes supported by the multilayer system. Rigorous coupled wave analysis (RCWA) is implemented to evaluate the absorbance. The optimized slot waveguide cell achieves a broadband absorption efficiency of 48.1% and more than 3-fold increase over the Yablonovitch limit and the optimized realistic organic cell exhibits nearly 50% average absorbance over the solar spectrum with short circuit current density five times larger than the control case using planar ITO layer.

  8. Light interaction with nano-structured diatom frustule, from UV-A to NIR

    DEFF Research Database (Denmark)

    Maibohm, Christian; Nielsen, Josefine Holm; Rottwitt, Karsten

    2016-01-01

    Diatoms are found in nearly every aqueous environment and play a vital part of the global primary production system contributing with up to 25 % and are efficient light harvesting organisms. Unique to diatoms are the hard cell wall, called the frustule surrounding the single cell. The frustule...... is made from bio-synthesized silicate, perforated by wavelength sized features where the morphology of the nano-structured “greenhouse” is species dependent. Diatoms would therefore make for one of the most interesting “green” resources since it has not only potential as a biomass production system...... but also for nano-structured inorganic material. To understand the biological significance and to integrate diatomic frustules as active material in devices a fundamental understanding of how light interacts with the frustule is needed. In this study we focus on centric diatoms, i.e. having rotational...

  9. Fabrication of various micro/nano structures by modified near-field electrospinning

    Directory of Open Access Journals (Sweden)

    T. P. Lei

    2015-04-01

    Full Text Available The modified near-field electrospinning (NFES and the conventional NFES have been compared to demonstrate the viability of direct-writing micro/nano structures from PVDF solution systems. The modified NFES shows good capability in writing various orderly micro/nano patterns, such as straight and continuous lines, parallel lines, arc lines, and beads-on-string structures, whereas the conventional NFES is difficult to give a continuous writing process. Besides, the modified NFES also allows a lower electric field due to the jet initiated in a mechanical way. By finely tuning the key parameters during the modified NFES process, such as the solution property, speed of the movable collector, and the distance between the spinneret and the collector, it is likely to construct complex patterns as required on rigid or flexible substrates for a myriad of applications.

  10. Nano-scale structure in membranes in relation to enzyme action - computer simulation vs. experiment

    DEFF Research Database (Denmark)

    Høyrup, P.; Jørgensen, Kent; Mouritsen, O.G.

    2002-01-01

    lengths are in the nano-meter range. The nano-scale structure is believed to be important for controlling the activity of enzymes, specifically phospholipases, which act at bilayer membranes. We propose here a lattice-gas statistical mechanical model with appropriate dynamics to account for the non......There is increasing theoretical and experimental evidence indicating that small-scale domain structure and dynamical heterogeneity develop in lipid membranes as a consequence of the the underlying phase transitions and the associated density and composition fluctuations. The relevant coherence......-equilibrium action of the enzyme phospholipase A(2) which hydrolyses lipid-bilayer substrates. The resulting product molecules are assumed to induce local variations in the membrane interfacial pressure. Monte Carlo simulations of the non-equilibrium properties of the model for one-component as well as binary lipid...

  11. Ni(OH){sub 2} and NiO nano structures: Synthesis, characterization and electrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Saghatforoush, Lotf Ali; Sanati, Soheila; Mehdizadeh, Robabeh [Payam Noor Univ., Tehran (Iran, Islamic Republic of); Hasanzadeh, Mohammad [Tabriz Univ. of Medical Sciences, Tabriz (Iran, Islamic Republic of)

    2012-04-15

    Hydrothermal route have been used in different conditions for preparation of Ni(OH){sub 2} nano structures. The NiO nanoparticles were obtained by calcining the Ni(OH){sub 2} precursor at 450 .deg. C for 2 h. The effect of sodium dodecyl sulfonate (SDS) as surfactant on the morphology and size of Ni(OH){sub 2} nanoparticles were discussed in detail. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectroscopy were used to characterize the products. The growth mechanism of the as-synthesized nano structures was also discussed in detail based on the experimental results. Coming up, the NiO nanoparticle modified carbon paste electrode was applied to the determination of captopril in aqueous solution.

  12. Avoided Crossing Patterns and Spectral Gaps of Surface Plasmon Modes in Gold Nano-Structures

    CERN Document Server

    Kolomenskii, Alexandre; Hembd, Jeshurun; Kolomenski, Andrei; Noel, John; Teizer, Winfried; Schuessler, Hans

    2010-01-01

    The transmission of ultrashort (7 fs) broadband laser pulses through periodic gold nano-structures is studied. The distribution of the transmitted light intensity over wavelength and angle shows an efficient coupling of the incident p-polarized light to two counter-propagating surface plasmon (SP) modes. As a result of the mode interaction, the avoided crossing patterns exhibit energy and momentum gaps, which depend on the configuration of the nano-structure and the wavelength. Variations of the widths of the SP resonances and an abrupt change of the mode interaction in the vicinity of the avoided crossing region are observed. These features are explained by the model of two coupled modes and a coupling change due to switching from the high frequency dark mode to the low frequency bright mode for increasing wavelength of the excitation light. PACS numbers: 73.20.Mf, 42.70.Qs, 42.25.-p,

  13. Electron emission degradation of nano-structured sp2-bonded amorphous carbon films

    Institute of Scientific and Technical Information of China (English)

    Lu Zhan-Ling; Wang Chang-Qing; Jia Yu; Zhang Bing-Lin; Yao Ning

    2007-01-01

    The initial field electron emission degradation behaviour of original nano-structured sp2-bonded amorphous carbon films has been observed.which can be attributed to the increase of the work function of the film in the field emission process analysed using a Fowler-Nordheim plot.The possible re.on for the change of work function is suggested to be the desorption of hydrogen from the original hydrogen termination film surface due to field emission current-induced local heating.For the explanation of the emission degradation behaviour of the nano-structured sp2-bonded amorphous carbon film,a cluster model with a series of graphite(0001) basal surfaces has been presented,and the theoretical calculations have been performed to investigate work functions of graphite(0001) surfaces with different hydrogen atom and ion chemisorption sites by using first principles method based on density functional theory-local density approximation.

  14. Synthesis and characterization of ZnO:TiO{sub 2} nano composites thin films deposited on glass substrate by sol-gel spray coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Sutanto, Heri, E-mail: herisutanto@undip.ac.id; Nurhasanah, Iis; Hidayanto, Eko; Wibowo, Singgih [Department of Physics, Faculty of Natural Sciences and Mathematics, Diponegoro University (Indonesia); Hadiyanto [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University (Indonesia)

    2015-12-29

    In this work, (ZnO){sub x}:(TiO{sub 2}){sub 1-x} nano composites thin films, with x = 1, 0.75, 0.5, 0.25, and 0, have been prepared by sol–gel spray coating technique onto glass substrate. Pure TiO{sub 2} and ZnO thin films were synthesized from titanium isopropoxide-based and zinc acetate-based precursor solutions, respectively, whereas the composite films were obtained from the mixture of these solutions at the specific % vol ratios. The properties and performance of nano composite ZnO, TiO{sub 2} and ZnO:TiO{sub 2} thin films at different composition have been investigated. Ultraviolet – Visible (UV-Vis) Spectrophotometer and Scanning Electron Microscopy (SEM) were employed in order to get morphology and transmittance of thin films. Testing the ability of photocatalytic activity of obtained films was conducted on photodegradation of methylene blue (MB) dye and organic pollutants of wastewater under a 30 watt UV light irradiation, then testing BOD, COD and TPC were conducted. Using the Tauc model, the band-gap energy decreased from 3.12 eV to 3.02 eV for the sample with x = 1 and 0, respectively. This decrease occured along with the replacement of percentage of ZnO by TiO{sub 2} on the films. This decrease also reduced the minimum energy that required for electron excitation. Obtained thin films had nanoscale roughness level with range 3.64 to 17.30 nm. The film with x= 0 has the biggest removal percentage on BOD, COD and TPC mesurements with percentage 54.82%, 62.73% and 99.88%, respectively.

  15. Synthesis and characterization of ZnO:TiO2 nano composites thin films deposited on glass substrate by sol-gel spray coating technique

    Science.gov (United States)

    Sutanto, Heri; Nurhasanah, Iis; Hidayanto, Eko; Wibowo, Singgih; Hadiyanto

    2015-12-01

    In this work, (ZnO)x:(TiO2)1-x nano composites thin films, with x = 1, 0.75, 0.5, 0.25, and 0, have been prepared by sol-gel spray coating technique onto glass substrate. Pure TiO2 and ZnO thin films were synthesized from titanium isopropoxide-based and zinc acetate-based precursor solutions, respectively, whereas the composite films were obtained from the mixture of these solutions at the specific % vol ratios. The properties and performance of nano composite ZnO, TiO2 and ZnO:TiO2 thin films at different composition have been investigated. Ultraviolet - Visible (UV-Vis) Spectrophotometer and Scanning Electron Microscopy (SEM) were employed in order to get morphology and transmittance of thin films. Testing the ability of photocatalytic activity of obtained films was conducted on photodegradation of methylene blue (MB) dye and organic pollutants of wastewater under a 30 watt UV light irradiation, then testing BOD, COD and TPC were conducted. Using the Tauc model, the band-gap energy decreased from 3.12 eV to 3.02 eV for the sample with x = 1 and 0, respectively. This decrease occured along with the replacement of percentage of ZnO by TiO2 on the films. This decrease also reduced the minimum energy that required for electron excitation. Obtained thin films had nanoscale roughness level with range 3.64 to 17.30 nm. The film with x= 0 has the biggest removal percentage on BOD, COD and TPC mesurements with percentage 54.82%, 62.73% and 99.88%, respectively.

  16. Structure-stress-resistivity relationship in WTi alloy ultra-thin and thin films prepared by magnetron sputtering

    Science.gov (United States)

    Le Priol, A.; Le Bourhis, E.; Renault, P.-O.; Muller, P.; Sik, H.

    2013-06-01

    WTi thin films were prepared from an alloyed target (W:Ti ˜ 70:30 at. %) by magnetron sputtering. Body-centered cubic WxTi1-x solid solutions with a {110} fiber texture and columnar grains have been produced with 0.75WTi thin films is about 60-200 μΩ cm, depending on the film thickness and microstructure (sputtering conditions). For both ultra-thin (9.5 nm) and thin (180 nm) films, a stress transition from compressive to tensile is observed as the working pressure increases. The process-structure-property relations of the WTi ultra-thin and thin films are discussed in relation with the state of the art.

  17. The Structural and Electrical Properties of Nanostructures ZnO Thin Films on Flexible Substrate

    Directory of Open Access Journals (Sweden)

    Nur Sa’adah Muhamad Sauki

    2017-06-01

    Full Text Available Zinc oxide (ZnO thin films were deposited on Teflon substrates by radio frequency (RF magnetron sputtering method at different substrate temperature. The dependence of residual stress on the substrate temperature was investigated in this work due to the growth process, the bombardment of energetic particles and process heating to the deposited thin films. From field emission scanning electron microscope (FESEM images, samples that deposited at various substrate temperatures consists nano-sized particles. The obtained X-ray diffraction (XRD results, it suggested that ZnO thin film deposited at 40oC with highly c-axis oriented shows unstressed film compared to other thin films. Besides that, the ZnO thin films deposited at 40oC shows improved electrical properties.

  18. Controllable Direct-Writing of Serpentine Micro/Nano Structures via Low Voltage Electrospinning

    OpenAIRE

    Feiyu Fang; Xin Chen; Zefeng Du; Ziming Zhu; Xindu Chen; Han Wang; Peixuan Wu

    2015-01-01

    Micro/nanofibers prepared by direct-writing using an electrospinning (ES) technique have drawn more attention recently owing to their intriguing physical properties and great potential as building blocks for micro/nanoscale devices. In this work, a wavy direct-writing (WDW) process was developed to directly write serpentine micro/nano structures suitable for the fabrication of micro devices. This fabrication ability will realize the application of electrospun-nanofiber-based wiring of structu...

  19. Simulation of coagulation and sintering of nano-structured particles using the moment method.

    Science.gov (United States)

    Park, Young-Kwon; Jung, Sang-Chul; Park, Sung Hoon

    2011-02-01

    In this study, a new method of simulating sintering of nano-structured particles in the frame of the moment method was developed. Simultaneous coagulation and sintering was simulated using the developed method and the results were compared with a more accurate numerical model. Good agreement was obtained between the model outputs while the new model was shown to be much more time-efficient.

  20. Evolution of nano-structures of silver due to rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Shyamal, E-mail: shyamal.mondal@saha.ac.in; Bhattacharyya, S. R., E-mail: shyamal.mondal@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata-700064 (India)

    2014-04-24

    This report deals with rapid thermal annealing (RTA) effect on continuous silver film on Si(100) substrate. For this purpose silver films of different thicknesses were deposited and subsequently annealed at 500 and 800 °C. The as-deposited and annealed samples were investigated by scanning electron microscope (SEM). Formations of different nano-structures have been observed. Fragmentation of formed nanoislands also observed at temperature below melting temperature.

  1. Nano/micro-structured Si/CNT/C composite from nano-SiO2 for high power lithium ion batteries.

    Science.gov (United States)

    Feng, Xuejiao; Yang, Jun; Bie, Yitian; Wang, Jiulin; Nuli, Yanna; Lu, Wei

    2014-11-07

    Nano/micro-structured pSi and pSi/CNT particles were synthesized from nano-SiO2 as both a template and silicon precursor via a combination of spray drying and magnesiothermic reduction, followed by a nano-layer carbon coating by chemical vapor deposition to obtain a nano/micro-structured pSi/C and pSi/CNT/C composite. In the hierarchical microstructure of the pSi/CNT/C composite, Si nanoparticles less than 20 nm in size were homogenously dispersed in an electronically conductive and porous network of multiwall carbon nanotubes, which can accommodate the volume changes in Si and improve the structural and conductive stability during repeated cycles leading to excellent electrochemical performance. The pSi/CNT/C presented reversible capacities of ca. 2100 mA h g(-1) at 1 A g(-1) and ca. 1370 mA h g(-1) at a high current rate of 5 A g(-1). Its capacity retention after 100 cycles was 95.5% at 1 A g(-1).

  2. Deposition of very thin uniform indium sulfide layers over metallic nano-rods by the Spray-Ion Layer Gas Reaction method

    Energy Technology Data Exchange (ETDEWEB)

    Genduso, G. [Dipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica, Università di Palermo, Viale delle Scienze, 90100 Palermo (Italy); Institut for Heterogeneous Material Systems, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Inguanta, R.; Sunseri, C.; Piazza, S. [Dipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica, Università di Palermo, Viale delle Scienze, 90100 Palermo (Italy); Kelch, C.; Sáez-Araoz, R. [Institut for Heterogeneous Material Systems, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Zykov, A. [Institut for Heterogeneous Material Systems, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); present address: Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15,12489 Berlin (Germany); Fischer, Ch.-H., E-mail: fischer@helmholtz-berlin.de [Institut for Heterogeneous Material Systems, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); second affiliation: Free University Berlin, Chemistry Institute, Takustr. 3, D-14195 Berlin (Germany)

    2013-12-02

    Very thin and uniform layers of indium sulfide were deposited on nickel nano-rods using the sequential and cyclical Spray-ILGAR® (Ion Layer Gas Reaction) technique. Substrates were fabricated by electrodeposition of Ni within the pores of polycarbonate membranes and subsequent chemical dissolution of the template. With respect to the depositions on flat substrates, experimental conditions were modified and optimized for the present geometry. Our results show that nano-rods up to a length of 10 μm were covered uniformly along their full length and with an almost constant film growth rate, thus allowing a good control of the coating thickness; the effect of the deposition temperature was also investigated. However, for high numbers of process steps, i.e. thickness, the films became uneven and crusty, especially at higher temperature, mainly owing to the simultaneous side reaction of the metallic Ni forming nickel sulfide at the surface of the rods. However, such a problem occurs only in the case of reactive nano-rod materials, such as less noble metals. It could be strongly reduced by doubling the spray step duration and thereby sealing the metallic surface before the process step of the sulfurization. Thus, quite smooth, about 100 nm thick coatings could be obtained. - Highlights: • Ni nano-rod substrates were grown within polycarbonate membranes. • We can coat nano-rods uniformly by the Ion Layer Gas Reaction method. • As a model we deposited up to about 100 nm In{sub 2}S{sub 3} on Ni nanorods (250 nm × 10 μm). • Element mapping at insulated rods showed homogenous coating over the full length. • Parameter optimization reduced effectively the Ni sulfide formation.

  3. Supercooling and cold energy storage characteristics of nano-media in ball-packed porous structures

    Directory of Open Access Journals (Sweden)

    Zhao Qunzhi

    2015-04-01

    Full Text Available The presented experiments aimed to study the supercooling and cold-energy storage characteristics of nanofluids and water-based nano-media in ball-packed porous structures (BPS. Titanium dioxide nanoparticles (TiO2 NPs measuring 20nm and 80nm were used as additives and sodium dodecyl benzene sulphonate (SDBS was used as anionic surfactant. The experiments used different concentrations of nanofluid, distilled with BPS of different spherical diameter and different concentrations of nano-media, and were conducted 20 times. Experimental results of supercooling were analysed by statistical methods. Results show that the average and peak supercooling degrees of nanofluids and nano-media in BPS are lower than those of distilled water. For the distilled water in BPS, the supercooling degree decreases on the whole with the decrease of the ball diameter. With the same spherical diameter (8mm of BPS, the supercooling degree of TiO2 NPs measuring 20nm is lower than the supercooling degree of distilled water in BPS. Step-cooling experiments of different concentrations of nanofluids and nano-media in BPS were also conducted. Results showed that phase transition time is reduced because of the presence of TiO2 NPs. The BPS substrate and the NPs enhance the heat transfer. Distilled water with a porous solid base and nanoparticles means the amount of cold-energy storage increases and the supercooling degree and the total time are greatly reduced. The phase transition time of distilled water is about 3.5 times that of nano-media in BPS.

  4. Preliminary Research on Structure and Properties of Nano-cellulose

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The structure of bacterial cellulose (BC) produced by Acetobacter xylinum NUST4 (A.xylinum NUST4) under static (SBC) and shake culture condition (ABC) was studied by means of transmission electron microscopic (TEM), X-ray diffraction (XRD) and Fourier transform-infrared spectrum (FT-IR). It was revealed that BC is Ⅰ crystal cellulose and the proportion of cellulose Ⅰα exceeds 80% and BC diameter is 10-80 nm.Mechanical properties and water absorption capacity were also determined. These properties could result from crystalline and nanometer structure of BC.

  5. A mechanism for enhanced photocatalytic activity of nano-size silver particle modified titanium dioxide thin films

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Ag-TiO2 nanostructured thin films with silver volume fraction of 0–20% were deposited on silicon and quartz substrates by RF magnetron sputtering and annealed in ambient air at 950°C for 1 h. The phase structure and surface topography of the films were characterized by X-ray diffractometer and transmission electron microscope. Photocatalytic activity of the films was evaluated by light induced degradation of methyl orange (C14H14N3NaO3S) solution using a high pressure mercury lamp as lamp-house. The relation of photocatalytic activity and silver content was studied in detail. It was found that silver content influences phase structure of TiO2 thin films, and silver in the films is metallic Ag (Ag0). With increasing silver content from 0 to 20 vol%, photocatalytic activity of the films increases first and then decreases. A suitable amount (2.5–5 vol%) silver addition can significantly enhance the photocatalytic activity of TiO2 films. The enhanced photocatalytic activity was mainly attributed to the extension of visible light absorption region of the films, the presence of anatase phase, the increase of oxy-gen anion radicals O2? and reactive center of surface Ti3+, and the better separation between electrons and holes on the films surface.

  6. Developments in Nano-Satellite Structural Subsystem Design at NASA-GSFC

    Science.gov (United States)

    Rossoni, Peter; Panetta, Peter V.

    1999-01-01

    The NASA-GSFC Nano-satellite Technology Development Program will enable flying constellations of tens to hundreds of nano-satellites for future NASA Space and Earth Science missions. Advanced technology components must be developed to make these future spacecraft compact, lightweight, low-power, low-cost, and survivable to a radiation environment over a two-year mission lifetime. This paper describes the efforts underway to develop lightweight, low cost, and multi-functional structures, serviceable designs, and robust mechanisms. As designs shrink, the integration of various subsystems becomes a vital necessity. This paper also addresses structurally integrated electrical power, attitude control, and thermal systems. These innovations bring associated fabrication, integration, and test challenges. Candidate structural materials and processes are examined and the merits of each are discussed. Design and fabrication processes include flat stock composite construction, cast aluminum-beryllium alloy, and an injection molded fiber-reinforced plastic. A viable constellation deployment scenario is described as well as a Phase-A Nano-satellite Pathfinder study.

  7. Uniting Superhydrophobic, Superoleophobic and Lubricant Infused Slippery Behavior on Copper Oxide Nano-structured Substrates

    Science.gov (United States)

    Ujjain, Sanjeev Kumar; Roy, Pritam Kumar; Kumar, Sumana; Singha, Subhash; Khare, Krishnacharya

    2016-01-01

    Alloys, specifically steel, are considered as the workhorse of our society and are inimitable engineering materials in the field of infrastructure, industry and possesses significant applications in our daily life. However, creating a robust synthetic metallic surface that repels various liquids has remained extremely challenging. The wettability of a solid surface is known to be governed by its geometric nano-/micro structure and the chemical composition. Here, we are demonstrating a facile and economical way to generate copper oxide micro-nano structures with spherical (0D), needle (1D) and hierarchical cauliflower (3D) morphologies on galvanized steel substrates using a simple chemical bath deposition method. These nano/micro textured steel surfaces, on subsequent coating of a low surface energy material display excellent superhydrophobic, superoleophobic and slippery behavior. Polydimethylsiloxane coated textured surfaces illustrate superhydrophobicity with water contact angle about 160°(2) and critical sliding angle ~2°. When functionalized with low-surface energy perfluoroalkylsilane, these surfaces display high repellency for low surface tension oils as well as hydrocarbons. Among them, the hierarchical cauliflower morphology exhibits re-entrant structure thereby showing the best superoleophobicity with contact angle 149° for dodecane. Once infused with a lubricant like silicone oil, they show excellent slippery behavior with low contact angle hysteresis (~ 2°) for water drops. PMID:27752098

  8. Universal wetting transition of an evaporating water droplet on hydrophobic micro- and nano-structures.

    Science.gov (United States)

    Bussonnière, Adrien; Bigdeli, Masoud B; Chueh, Di-Yen; Liu, Qingxia; Chen, Peilin; Tsai, Peichun Amy

    2017-02-07

    Water-repellent, rough surfaces have a remarkable and beneficial wetting property: when a water droplet comes in contact with a small fraction of the solid, both liquid-solid adhesion and hydrodynamic drag are reduced. As a prominent example from nature, the lotus leaf-comprised of a wax-like material with micro- and nano-scaled roughness-has recently inspired numerous syntheses of superhydrophobic substrates. Due to the diverse applications of superhydrophobicity, much research has been devoted to the fabrication and investigations of hydrophobic micro-structures using established micro-fabrication techniques. However, wetting transitions remain relatively little explored. During evaporation, a water droplet undergoes a wetting transition from a (low-frictional) partial to (adhesive) complete contact with the solid, destroying the superhydrophobicity and the self-cleaning properties of the slippery surface. Here, we experimentally examine the wetting transition of a drying droplet on hydrophobic nano-structures, a previously unexplored regime. In addition, using a theoretical analysis we found a universal criterion of this wetting transition that is characterized by a critical contact angle. Different from previous results showing different critical droplet sizes, our results show a universal, geometrically-dependent, critical contact angle, which agrees well with various data for both hydrophobic micro- and nano-structures.

  9. Transparent, self-cleaning and waterproof surfaces with tunable micro/nano dual-scale structures

    Science.gov (United States)

    Lee, Yujin; You, Eun-Ah; Ha, Young-Geun

    2016-09-01

    The rational design and facile fabrication of optically transparent, superhydrophobic surfaces can advance their versatile applications, including optoelectronic devices. For the easily accessible and scalable preparation of transparent, superhydrophobic surfaces, various coating methods using a solution-process have been developed. However, obtaining highly transparent, non-wetting surfaces with excellent properties is challenging due to the difficulty in controlling surface roughness. Here, we report on a novel approach to control the surface roughness by fabricating tailorable micro/nano dual-scale surface structures via solution-processed nanoparticle coating. The surface roughness was able to be controlled by micro/nano dual-scale structures that can be manipulated by varying the mixture ratio of two different sizes of Al2O3 nanoparticles. The controllable micro/nano dual-scale structures were optimized to achieve the superior surface properties in both hydrophobicity and transparency, exhibiting a high water contact angle (>160°), low sliding angle (90%). These characteristics allowed an excellent transparency and self-cleaning capability as well as a superior waterproof ability even under applied voltage. Furthermore, we demonstrated the versatile applicability of the developed surface-coating method to a wide range of substrates including glass, paper, fabrics, and even flexible plastics.

  10. Uniting Superhydrophobic, Superoleophobic and Lubricant Infused Slippery Behavior on Copper Oxide Nano-structured Substrates

    Science.gov (United States)

    Ujjain, Sanjeev Kumar; Roy, Pritam Kumar; Kumar, Sumana; Singha, Subhash; Khare, Krishnacharya

    2016-10-01

    Alloys, specifically steel, are considered as the workhorse of our society and are inimitable engineering materials in the field of infrastructure, industry and possesses significant applications in our daily life. However, creating a robust synthetic metallic surface that repels various liquids has remained extremely challenging. The wettability of a solid surface is known to be governed by its geometric nano-/micro structure and the chemical composition. Here, we are demonstrating a facile and economical way to generate copper oxide micro-nano structures with spherical (0D), needle (1D) and hierarchical cauliflower (3D) morphologies on galvanized steel substrates using a simple chemical bath deposition method. These nano/micro textured steel surfaces, on subsequent coating of a low surface energy material display excellent superhydrophobic, superoleophobic and slippery behavior. Polydimethylsiloxane coated textured surfaces illustrate superhydrophobicity with water contact angle about 160°(2) and critical sliding angle ~2°. When functionalized with low-surface energy perfluoroalkylsilane, these surfaces display high repellency for low surface tension oils as well as hydrocarbons. Among them, the hierarchical cauliflower morphology exhibits re-entrant structure thereby showing the best superoleophobicity with contact angle 149° for dodecane. Once infused with a lubricant like silicone oil, they show excellent slippery behavior with low contact angle hysteresis (~ 2°) for water drops.

  11. Thin film nano solar cells--from device optimization to upscaling.

    Science.gov (United States)

    Toivola, Minna; Peltola, Time; Miettunen, Kati; Halme, Janne; Lund, Peter

    2010-02-01

    Stainless steel based dye solar cells have been upscaled from small, laboratory size test cells of 0.32 cm2 active area to 6 cm x 6 cm "mini-modules" with active areas ca. 15 cm2. Stainless steel works as the photoelectrode substrate whilst the counter electrode is prepared on indium-doped tin oxide coated polyethyleneterephtalate or polyethylenenaphtalate plastic foil (fluorine-doped tin oxide coated glass as a reference). Additional current collector structures were deposited on the counter electrode substrate with inkjet-printing of silver nanoparticle ink in order to reduce the lateral resistance of the plastic foil. Flexible substrates enable roll-to-roll type industrial manufacturing of the cells and the steel's superior conductivity compared to the typical substrate materials such as glass and plastic makes it possible to prepare even substantially larger modules. The best efficiencies obtained this far with the "mini-module" using a stainless steel photoelectrode are 2.5% with a platinum-sputtered indium-doped tin oxide coated polyethyleneterephtalate counter electrode and 3.4% with a thermally platinized fluorine-doped tin oxide coated glass counter electrode. These efficiencies are on the same level than those measured with small cells prepared with similar methods and materials (3.4%-4.7%, depending on configuration, which are amongst the highest reported for this kind of a dye solar cell). Replacing expensive conducting glass with steel and plastic foils as the substrate materials leads also to economical savings in the cell production.

  12. Extreme strain rate and temperature dependence of the mechanical properties of nano silicon nitride thin layers in a basal plane under tension: a molecular dynamics study.

    Science.gov (United States)

    Lu, Xuefeng; Wang, Hongjie; Wei, Yin; Wen, Jiangbo; Niu, Min; Jia, Shuhai

    2014-08-01

    Molecular dynamics simulations are performed to clarify the extreme strain rate and temperature dependence of the mechanical behaviors of nano silicon nitride thin layers in a basal plane under tension. It is found that fracture stresses show almost no change with increasing strain rate. However, fracture strains decrease gradually due to the appearance of additional N(2c)-Si bond breaking defects in the deformation process. With increasing loading temperature, there is a noticeable drop in fracture stress and fracture strain. In the low temperature range, roughness phases can be observed owing to a combination of factors such as configuration evolution and energy change.

  13. Fabrication and characterization of micro- /nano structures for nanophotonic applications

    Science.gov (United States)

    Jee, Hongsub

    The objective of this thesis is finding and developing fabrication methods to provide background techniques for potential applications with nanomaterials. The inclined UV lithography has announced to make three-dimensional fabrication process. With a movable stage, complex structures were achieved but difference of the refractive index, design of the final structures were limited. Refractive index matching medium between the substrate and the light source could reduce the refractive indices between the polymer and the substrate successfully. Nanoporous structures fabricated by multibeam interference lithography shows limitation of the usage since its periodicity. By insertion of the lift off resist layer between the patterned layer and the substrate, final photonic crystal structures could be partially removed for its own purpose and it provide potential application in the future. Two-step processing, combining with reactive ion etching system, nanoporous structures were on various substrates such as silicon and Polydimethylsiloxane. Photonic crystal template anodic aluminum oxide process has been described too. Large optical activity at visible wavelengths are of great attention in photonics. Dramatic enhancement of the optical activity of chiral poly(fluorene-alt-benzothiadiazole) with photoresist was demonstrated and successive photo patterning of chiral polymer shows the potential usage of this material for the photonics applications. Two photon lithography also used to pattern a photoresist-chiral polymer mixture into planar shapes and enhanced chirality can be realized by tuning the wavelength-dependent chiral response at both the molecular and geometric level. Near infrared light induced photopolymerization in-situ was demonstrated which can be applied everywhere where ultraviolet-polymerization is employed such as dentistry, coating industry. Use of the ultraviolet upconverting nanoparticles doped into the polymer, we show that expensive femtosecond pulsed

  14. Co-Assembled Supported Catalysts: Synthesis of Nano-Structured Supported Catalysts with Hierarchic Pores through Combined Flow and Radiation Induced Co-Assembled Nano-Reactors

    Directory of Open Access Journals (Sweden)

    Galip Akay

    2016-05-01

    Full Text Available A novel generic method of silica supported catalyst system generation from a fluid state is presented. The technique is based on the combined flow and radiation (such as microwave, thermal or UV induced co-assembly of the support and catalyst precursors forming nano-reactors, followed by catalyst precursor decomposition. The transformation from the precursor to supported catalyst oxide state can be controlled from a few seconds to several minutes. The resulting nano-structured micro-porous silica supported catalyst system has a surface area approaching 300 m2/g and X-ray Diffraction (XRD-based catalyst size controlled in the range of 1–10 nm in which the catalyst structure appears as lamellar sheets sandwiched between the catalyst support. These catalyst characteristics are dependent primarily on the processing history as well as the catalyst (Fe, Co and Ni studied when the catalyst/support molar ratio is typically 0.1–2. In addition, Ca, Mn and Cu were used as co-catalysts with Fe and Co in the evaluation of the mechanism of catalyst generation. Based on extensive XRD, Scanning Electron Microscopy (SEM and Transmission Electron Microscopy (TEM studies, the micro- and nano-structure of the catalyst system were evaluated. It was found that the catalyst and silica support form extensive 0.6–2 nm thick lamellar sheets of 10–100 nm planar dimensions. In these lamellae, the alternate silica support and catalyst layer appear in the form of a bar-code structure. When these lamellae structures pack, they form the walls of a micro-porous catalyst system which typically has a density of 0.2 g/cm3. A tentative mechanism of catalyst nano-structure formation is provided based on the rheology and fluid mechanics of the catalyst/support precursor fluid as well as co-assembly nano-reactor formation during processing. In order to achieve these structures and characteristics, catalyst support must be in the form of silane coated silica nano

  15. Fabrication of nano-structures on glass substrate by modified nano-imprint patterning with a plasma-induced surface-oxidized Cr mask

    Science.gov (United States)

    Lee, So Hee; Lee, Su Yeon; Lee, Seong Eui; Lee, Heon; Lee, Hee Chul

    2014-03-01

    In this study, we introduce a process for fabrication of nano-sized structural arrays on glass using modified nano-imprint patterning. A PVC (polyvinyl chloride) stamp was prepared by hot embossing, and a Cr-oxide-pattern etch-mask was used. The etch-mask was formed by oxidizing the surface of exposed Cr region by oxygen plasma treatment at room temperature. The fabrication of the etch-mask was conducted by immersing the locally oxidized Cr pattern in resin remover and Cr-etchant. The residual UV resin and un-oxidized Cr pattern were selectively removed, resulting in the obvious array of Cr-oxide etch-mask-pattern. The array of glass nano-structures was formed by reactive ion etching (RIE) using CF4 and Ar gas discharge. After removing the Cr-oxide mask, the final nano-structure had a height of 40 nm and a diameter of 170 nm, which was slightly less than the diameter of the original master-mold. The plasma treatment gave rise to a rough glass surface with root-mean-square (RMS) roughness of 29.25 nm, while that of bare glass was 0.66 nm. A high optical transmittance due to reduction in reflectance was observed at the plasma-treated rough surface, as well as for the array of nano-structures. The highest measured optical transmittance was 97.2% at a wavelength of 550 nm; an increase of about 7.2% compared to bare glass.

  16. Atomistic tensile deformation mechanisms of Fe with gradient nano-grained structure

    Directory of Open Access Journals (Sweden)

    Wenbin Li

    2015-08-01

    Full Text Available Large-scale molecular dynamics (MD simulations have been performed to investigate the tensile properties and the related atomistic deformation mechanisms of the gradient nano-grained (GNG structure of bcc Fe (gradient grains with d from 25 nm to 105 nm, and comparisons were made with the uniform nano-grained (NG structure of bcc Fe (grains with d = 25 nm. The grain size gradient in the nano-scale converts the applied uniaxial stress to multi-axial stresses and promotes the dislocation behaviors in the GNG structure, which results in extra hardening and flow strength. Thus, the GNG structure shows slightly higher flow stress at the early plastic deformation stage when compared to the uniform NG structure (even with smaller grain size. In the GNG structure, the dominant deformation mechanisms are closely related to the grain sizes. For grains with d = 25 nm, the deformation mechanisms are dominated by GB migration, grain rotation and grain coalescence although a few dislocations are observed. For grains with d = 54 nm, dislocation nucleation, propagation and formation of dislocation wall near GBs are observed. Moreover, formation of dislocation wall and dislocation pile-up near GBs are observed for grains with d = 105 nm, which is the first observation by MD simulations to our best knowledge. The strain compatibility among different layers with various grain sizes in the GNG structure should promote the dislocation behaviors and the flow stress of the whole structure, and the present results should provide insights to design the microstructures for developing strong-and-ductile metals.

  17. Determination of standard molar enthalpies of formation of SrMoO{sub 4} micro/nano structures

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yunxiao; Fan, Gaochao [College of Chemistry and Ecological Engineering, Guangxi University for Nationalities, Nanning 530006 (China); Huang, Zaiyin, E-mail: huangzaiyin@163.com [College of Chemistry and Ecological Engineering, Guangxi University for Nationalities, Nanning 530006 (China); Sun, Jilong; Wang, Lude; Wang, Tenghui; Chen, Jie [College of Chemistry and Ecological Engineering, Guangxi University for Nationalities, Nanning 530006 (China)

    2012-02-20

    Graphical abstract: Schematic illustration of thermochemical cycle between the nano and bulk reaction systems. Highlights: Black-Right-Pointing-Pointer A thermochemical cycle was designed. Black-Right-Pointing-Pointer Relationship of standard molar enthalpies of formation between micro/nano and bulk SrMoO{sub 4} was gained. Black-Right-Pointing-Pointer Microcalorimetry was used as a supplementary technology. Black-Right-Pointing-Pointer Standard molar enthalpies of formation of the synthesized micro/nano SrMoO{sub 4} were obtained. Black-Right-Pointing-Pointer This novel approach can be used to other micro/nano materials. - Abstract: SrMoO{sub 4} micro/nano structures were prepared by a simple reverse microemulsion method and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscope (SEM). In order to associate standard molar enthalpies of formation of nano SrMoO{sub 4} with bulk SrMoO{sub 4}, the relationship of them was obtained through designing a thermochemical cycle according to thermodynamic potential function method. Combined with microcalorimetry, the standard molar enthalpies of formation of the synthesized micro/nano SrMoO{sub 4} at 298.15 K were gained in this paper. And the variation of standard molar enthalpies of formation of micro/nano SrMoO{sub 4} with different morphologies and sizes was discussed.

  18. Integrating Bioengineered F1 Motors into Nano-Structured Surfaces

    Science.gov (United States)

    2013-04-23

    Cindy Berrie, Fei Gao. Insertion of a Rigid Structural Element into the Regulatory Domain of the Chloroplast F1-ATPase Gamma Subunit for Rotational...Studies., 15th International Photosynthesis Congress. 2010/08/22 01:00:00, . : , 12/27/2011 3.00 . The Mutation E242K in the chloroplast ATP synthase... chloroplast F1-ATPase gamma subunit for rotational studies. Proceedings of the 15th International Congress on Photosynthesis, 2011, pp.123-126. 2. Colvert

  19. Materials science in microelectronics I the relationships between thin film processing and structure

    CERN Document Server

    Machlin, Eugene

    2005-01-01

    Thin films play a key role in the material science of microelectronics, and the subject matter of thin-films divides naturally into two headings: processing / structure relationship, and structure / properties relationship.The first volume of Materials Science in Microelectronics focuses on the first relationship - that between processing and the structure of the thin-film. The state of the thin film's surface during the period that one monolayer exists - before being buried in the next layer - determines the ultimate structure of the thin film, and thus its properties. This

  20. Potential of nano-technology for applications in the energy area; Potenziale der Nanotechnologien fuer Anwendungen im Energiebereich

    Energy Technology Data Exchange (ETDEWEB)

    Hoehener, K.; Moeckli, M.

    2002-07-01

    This short report for the Swiss Federal Office of Energy (SFOE) presents an overview on nano-technologies and reviews their potential for use in the energy area. Three categories - nano-materials, nano-structures and nano-structuring - are proposed and described. Illustrative examples for each category are given and their possible use in the materials, energy-efficiency and renewable energy areas are discussed. Reference is made to projects being carried out under the Swiss 'Top-Nano 21' programme including thermally protective coatings for gas-turbine components, cold-cathode fluorescent lamps and thin-film solar cells.

  1. Thin films of tetrafluorosubstituted cobalt phthalocyanine: Structure and sensor properties

    Energy Technology Data Exchange (ETDEWEB)

    Klyamer, Darya D.; Sukhikh, Aleksandr S. [Nikolaev Institute of Inorganic Chemistry SB RAS, Lavrentiev Pr. 3, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2 (Russian Federation); Krasnov, Pavel O. [Nikolaev Institute of Inorganic Chemistry SB RAS, Lavrentiev Pr. 3, Novosibirsk 630090 (Russian Federation); Gromilov, Sergey A. [Nikolaev Institute of Inorganic Chemistry SB RAS, Lavrentiev Pr. 3, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2 (Russian Federation); Morozova, Natalya B. [Nikolaev Institute of Inorganic Chemistry SB RAS, Lavrentiev Pr. 3, Novosibirsk 630090 (Russian Federation); Basova, Tamara V., E-mail: basova@niic.nsc.ru [Nikolaev Institute of Inorganic Chemistry SB RAS, Lavrentiev Pr. 3, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2 (Russian Federation)

    2016-05-30

    Highlights: • Thin films of tetrafluorosubstituted cobalt phthalocyanine were studied. • The effect of fluorine substituents to the films structure and properties was verified. • The sensor response of tetrafluorosubstituted phthalocyanine toward NH{sub 3} was studied. • The structure of analyte/phthalocyanine complex was analysed using DFT calculations. - Abstract: In this work, thin films of tetrafluorosubstituted cobalt phthalocyanine (CoPcF{sub 4}) were prepared by organic molecular beam deposition and their structure was studied using UV–vis, polarization dependent Raman spectroscopy, XRD and atomic force microscopy. Quantum chemical calculations (DFT) have been employed in order to determine the detailed assignment of the bands in the CoPcF{sub 4} IR and Raman spectra. The electrical sensor response of CoPcF{sub 4} films to ammonia vapours was investigated and compared with that of unsubstituted cobalt phthalocyanine films. In order to explain the difference in sensitivity of the unsubstituted and fluorinated phthalocyanines to ammonia, the nature and properties of chemical binding between CoPc derivatives and NH{sub 3} were described by quantum-chemical calculations utilizing DFT method. The effect of post-deposition annealing on surface morphology and gas sensing properties of CoPcF{sub 4} films was also studied.

  2. Arbitrarily thin metamaterial structure for perfect absorption and giant magnification

    DEFF Research Database (Denmark)

    Jin, Yi; Xiao, Sanshui; Mortensen, N. Asger

    2011-01-01

    In our common understanding, for strong absorption or amplification in a slab structure, the desire of reducing the slab thickness seems contradictory to the condition of small loss or gain. In this paper, this common understanding is challenged. It is shown that an arbitrarily thin metamaterial...... layer can perfectly absorb or giantly amplify an incident plane wave at a critical angle when the real parts of the permittivity and permeability of the metamaterial are zero while the absolute imaginary parts can be arbitrarily small. The metamaterial layer needs a totally reflective substrate...

  3. Magnetic properties and structure of very thin permalloy films

    Institute of Scientific and Technical Information of China (English)

    Guanghua Yu; Haifeng Li; Tao Yang; Fengwu Zhu

    2004-01-01

    In order to study the magnetic properties and structure of very thin permalloy films, Ni81Fe19 films of 12 nm in thickness were prepared by different instruments at an ultrahigh base vacuum and a lower base vacuum. The anisotropic magnetoresistance coefficients (△R/R) of Ni81Fe19 (12 nm) films reached 1.6 % and 0.6 %, and the coercivities were 127 and 334 A/m, respectively. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to study the structure and surface chemical state. The experimental results show that the films prepared at the ultrahigh base vacuum have a smoother surface, a bigger grain size and a denser structure with fewer defects than those prepared at the lower base vacuum.

  4. Multi-Beam Interference Advances and Applications: Nano-Electronics, Photonic Crystals, Metamaterials, Subwavelength Structures, Optical Trapping, and Biomedical Structures

    Directory of Open Access Journals (Sweden)

    Thomas K. Gaylord

    2011-06-01

    Full Text Available Research in recent years has greatly advanced the understanding and capabilities of multi-beam interference (MBI. With this technology it is now possible to generate a wide range of one-, two-, and three-dimensional periodic optical-intensity distributions at the micro- and nano-scale over a large length/area/volume. These patterns may be used directly or recorded in photo-sensitive materials using multi-beam interference lithography (MBIL to accomplish subwavelength patterning. Advances in MBI and MBIL and a very wide range of applications areas including nano-electronics, photonic crystals, metamaterials, subwavelength structures, optical trapping, and biomedical structures are reviewed and put into a unified perspective.

  5. Insight into the nanomechanical properties under indentation of β-Si3N4 nano-thin layers in the basal plane using molecular dynamics simulation.

    Science.gov (United States)

    Lu, Xuefeng; Guo, Xin; La, Peiqing; Wei, Yupeng; Nan, Xueli; He, Ling

    2014-09-21

    Molecular dynamics simulations were performed to clarify the nanomechanical responses of β-Si3N4 nano-thin layers in the basal plane for indenters of various radii, different indentation velocities and at different temperatures. It was found that the maximum loading stress and indenter displacement both increase with increasing radius of the indenter. A large number of N(6h)-Si bond-breaking defects and one N(2c)-Si bond-breaking defects are responsible for the initiation of fracturing. With increasing loading velocity, the maximum loading stresses show almost no change; however, a high loading velocity can shorten the displacement of the indenter and contributes to the formation of new N(2c)-Si bond-breaking defects. Thermal fluctuations can decrease the mechanical properties of the thin layer. The maximum loading stresses and indenter displacements are sensitive to both the radius of the indenter and the loading temperature.

  6. Peparation and Characterization of Nano-structured Oxides for Supercapacitors

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results The rapid and complete precipitation of RuO2·xH2O in the initial hydrothermal period (< 45 min) results in the uniform size and narrow particle distribution (1-3 nm).Prolonging the hydrothermal time favors the condensation of hydroxyl groups coupled with the formation of a local RuO6 rutile crystalline structure in every particulate but retards the water loss.This method is proposed as"hydrothermal annealing" for the independent control of crystal size and water content of RuO2.The crystalline...

  7. Nano-Biotechnology: Structure and Dynamics of Nanoscale Biosystems

    CERN Document Server

    Manjasetty, Babu A; Ramaswamy, Y S

    2010-01-01

    Nanoscale biosystems are widely used in numerous medical applications. The approaches for structure and function of the nanomachines that are available in the cell (natural nanomachines) are discussed. Molecular simulation studies have been extensively used to study the dynamics of many nanomachines including ribosome. Carbon Nanotubes (CNTs) serve as prototypes for biological channels such as Aquaporins (AQPs). Recently, extensive investigations have been performed on the transport of biological nanosystems through CNTs. The results are utilized as a guide in building a nanomachinary such as nanosyringe for a needle free drug delivery.

  8. Metamaterial-based theoretical description of light scattering by metallic nano-hole array structures

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London N6A 3K7 (Canada); Najiminaini, Mohamadreza; Carson, Jeffrey J. L. [Lawson Health Research Institute, St. Joseph' s Health Care, 268 Grosvenor Street, London N6A 4V2 (Canada); Department of Medical Biophysics, University of Western Ontario, London N6A 3K7 (Canada); Balakrishnan, Shankar [Department of Physics and Astronomy, University of Western Ontario, London N6A 3K7 (Canada); Lawson Health Research Institute, St. Joseph' s Health Care, 268 Grosvenor Street, London N6A 4V2 (Canada); Department of Medical Biophysics, University of Western Ontario, London N6A 3K7 (Canada)

    2015-05-14

    We have experimentally and theoretically investigated the light-matter interaction in metallic nano-hole array structures. The scattering cross section spectrum was measured for three samples each having a unique nano-hole array radius and periodicity. Each measured spectrum had several peaks due to surface plasmon polaritons. The dispersion relation and the effective dielectric constant of the structure were calculated using transmission line theory and Bloch's theorem. Using the effective dielectric constant and the transfer matrix method, the surface plasmon polariton energies were calculated and found to be quantized. Using these quantized energies, a Hamiltonian for the surface plasmon polaritons was written in the second quantized form. Working with the Hamiltonian, a theory of scattering cross section was developed based on the quantum scattering theory and Green's function method. For both theory and experiment, the location of the surface plasmon polariton spectral peaks was dependant on the array periodicity and radii of the nano-holes. Good agreement was observed between the experimental and theoretical results. It is proposed that the newly developed theory can be used to facilitate optimization of nanosensors for medical and engineering applications.

  9. Subsurface defects structural evolution in nano-cutting of single crystal copper

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Quanlong [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Bai, Qingshun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Chen, Jiaxuan, E-mail: wangquanlong0@hit.edu.cn [Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, Yazhou [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Guo, Yongbo [Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Liang, Yingchun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-07-30

    Highlights: • An innovative analysis method is adopted to analyze nano-cutting process accurately. • A characteristic SFT and stair-rod dislocation are found in subsurface defect layer. • The formation mechanism of stair-rod dislocation is investigated. • The local atomic structure of subsurface defects is introduced. - Abstract: In this work, molecular dynamics simulation is performed to study the subsurface defects structural distribution and its evolution during nano-cutting process of single crystal copper. The formation mechanism of chip and machined surface is interviewed by analyzing the dislocation evolution and atomic migration. The centro-symmetry parameter and spherical harmonics method are adopted to characterize the distribution and evolution of the subsurface defect structures and local atomic structures. The results show that stacking faults, dislocation loops, “V-shaped” dislocation loops, and plenty of point defects are formed during the machined surface being formed in shear-slip zone. In subsurface damage layers, stair-rod dislocation, stacking fault tetrahedra, atomic cluster defect, and vacancy defect are formed. And the formation mechanism of stair-rod dislocation is investigated by atomic-scale structure evolution. The local atomic structures of subsurface defects are icosahedrons, hexagonal close packed, body-centered cubic, and defect face center cubic, and the variations of local atomic structures are investigated.

  10. Structure and Properties of poly (para phynelyne benzobisoxazole) (PBO) /single wall carbon nano tube composite fibers

    Science.gov (United States)

    Kumar, Satish; Zhang, Xiefei; Bhattacharyya, Arup R.; Min, Byung G.; Dang, T. D.; Arnold, F. E.; Vaia, Richard A.; Ramesh, S.; Willis, P. A.; Hauge, R. H.; Smalley, R. E.

    2002-03-01

    The liquid crystalline compositions are prepared by the in-situ polycondensation of diamines and diacid monomers in the presence of single wall carbon nano tubes (SWNT). Processing of the new compositions into fibers provide hybrid materials with improved mechanical properties. The in-situ polymerizations were carried out in polyphosphoric acid (PPA). Carbon nano tubes as high as 10 wt.polymer weight have been utilized. Fiber spinning has been carried out using dry jet wet spinning using a piston driven spinning system and the fiber coagulated in water and subsequently vacuum dried and heat treated in nitrogen at 400oC. Structure and properties of these fibers have been studied. Tensile strength of the composite fibers increased by about 50morphology of these fibers have been studied using X- ray diffraction and scanning electron microscopy.

  11. Vibrational nano-spectroscopic imaging correlating structure with intermolecular coupling and dynamics.

    Science.gov (United States)

    Pollard, Benjamin; Muller, Eric A; Hinrichs, Karsten; Raschke, Markus B

    2014-04-11

    Molecular self-assembly, the function of biomembranes and the performance of organic solar cells rely on nanoscale molecular interactions. Understanding and control of such materials have been impeded by difficulties in imaging their properties with the desired nanometre spatial resolution, attomolar sensitivity and intermolecular spectroscopic specificity. Here we implement vibrational scattering-scanning near-field optical microscopy with high spectral precision to investigate the structure-function relationship in nano-phase separated block copolymers. A vibrational resonance is used as a sensitive reporter of the local chemical environment and we image, with few nanometre spatial resolution and 0.2 cm(-1) spectral precision, solvatochromic Stark shifts and line broadening correlated with molecular-scale morphologies. We discriminate local variations in electric fields between nano-domains with quantitative agreement with dielectric continuum models. This ability to directly resolve nanoscale morphology and associated intermolecular interactions can form a basis for the systematic control of functionality in multicomponent soft matter systems.

  12. Nano-structured carbon materials for improved biosensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Razumiene, J., E-mail: julija.razumiene@bchi.vu.lt [Institute of Biochemistry, Vilnius University, Mokslininku 12, Vilnius 08662 (Lithuania); Sakinyte, I. [Institute of Biochemistry, Vilnius University, Mokslininku 12, Vilnius 08662 (Lithuania); Barkauskas, J. [Faculty of Chemistry, Vilnius University, Naugarduko 24, Vilnius 03225 (Lithuania); Baronas, R. [Faculty of Mathematics and Informatics, Vilnius University, Naugarduko 24, Vilnius 03225 (Lithuania)

    2015-04-15

    Graphical abstract: - Highlights: • Novel protocols of graphite oxidation were used for successful synthesis of GOPs. • Newly synthesized GOPs were applicable for electrode design in reagentless bioelectrocatalytic systems operating on direct electron transfer. • We show that bioelectrocatalytic processes strongly depend on functionalities, morphology and structural features of GOPs. - Abstract: A set of oxidized graphite samples have been newly synthesized using different protocols. Atomic force microscopy, Raman spectroscopy, thermal gravimetric analysis and Brunauer–Emmett–Teller analysis revealed the changes in structure and functionalities of obtained graphite oxidation products (GOPs) compared to pristine graphite. The substances have been tested as electrode materials applicable for bioelectrocatalytic systems using pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH). The application of GOPs allowed achieving the direct electron transfer (DET) from active site of PQQ-GDH to the electrode surface. Needless of additional electron transfer (ET) mediating compounds highly improved features of the biosensors. The efficiency of the biosensors has been evaluated for all types of biosensors varied from 32 μA/cm{sup 2} to 64 μA/cm{sup 2} using as electrode materials GOP1 and thermally reduced graphite oxide (TRGO), respectively. TRGO containing function groups (according TGA, ∼6% of the weight loss) and smallest particles (average diameter was ∼11 nm and the average height was ∼0.5 nm) exhibited the higher efficiency for ET acceleration in the biosensor acting on principle of DET.

  13. 3D printing of nano- and micro-structures

    Science.gov (United States)

    Ramasamy, Mouli; Varadan, Vijay K.

    2016-04-01

    Additive manufacturing or 3D printing techniques are being vigorously investigated as a replacement to the traditional and conventional methods in fabrication to bring forth cost and time effective approaches. Introduction of 3D printing has led to printing micro and nanoscale structures including tissues and organelles, bioelectric sensors and devices, artificial bones and transplants, microfluidic devices, batteries and various other biomaterials. Various microfabrication processes have been developed to fabricate micro components and assemblies at lab scale. 3D Fabrication processes that can accommodate the functional and geometrical requirements to realize complicated structures are becoming feasible through advances in additive manufacturing. This advancement could lead to simpler development mechanisms of novel components and devices exhibiting complex features. For instance, development of microstructure electrodes that can penetrate the epidermis of the skin to collect the bio potential signal may prove very effective than the electrodes that measure signal from the skin's surface. The micro and nanostructures will have to possess extraordinary material and mechanical properties for its dexterity in the applications. A substantial amount of research being pursued on stretchable and flexible devices based on PDMA, textiles, and organic electronics. Despite the numerous advantages these substrates and techniques could solely offer, 3D printing enables a multi-dimensional approach towards finer and complex applications. This review emphasizes the use of 3D printing to fabricate micro and nanostructures for that can be applied for human healthcare.

  14. Low temperature acetone detection by p-type nano-titania thin film: Equivalent circuit model and sensing mechanism

    Science.gov (United States)

    Bhowmik, B.; Dutta, K.; Hazra, A.; Bhattacharyya, P.

    2014-09-01

    Undoped nanocrystalline anatase p-type TiO2 thin film was deposited by sol-gel method on thermally oxidized p-Si (2-5 Ω cm, ) substrates. The thin film was characterized by X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) to confirm the formation of nanocrystalline anatase titania and to determine the crystallite size (∼7 nm). The resistive sensor structure was fabricated employing two lateral Pd electrodes on top of the TiO2 sensing layer. The developed sensor was tested in the temperature range of 50-200 °C for the detection of low ppm acetone (0.5-50 ppm). The maximum response of ∼115% was obtained at 150 °C with response/recovery time of 14 s/22 s at 50 ppm acetone (in air). Moreover, the sensors were capable of detecting acetone as low as 0.5 ppm with acceptable response magnitude. As titania acetone sensors are mostly n-TiO2 based, the acetone sensing mechanism for p-TiO2 is yet to be established authentically. To address the issue, an equivalent circuit model, based on the corresponding band diagram of nanocrystalline p-TiO2 with Pd electrode, was developed to describe the electron transfer mechanism through grain, grain boundary and Pd electrode under the influence of acetone vapor.

  15. A micro oxygen sensor based on a nano sol-gel TiO2 thin film.

    Science.gov (United States)

    Wang, Hairong; Chen, Lei; Wang, Jiaxin; Sun, Quantao; Zhao, Yulong

    2014-09-03

    An oxygen gas microsensor based on nanostructured sol-gel TiO2 thin films with a buried Pd layer was developed on a silicon substrate. The nanostructured titania thin films for O2 sensors were prepared by the sol-gel process and became anatase after heat treatment. A sandwich TiO2 square board with an area of 350 μm × 350 μm was defined by both wet etching and dry etching processes and the wet one was applied in the final process due to its advantages of easy control for the final structure. A pair of 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer was fabricated on the board by a lift-off process. The sensor chip was tested in a furnace with changing the O2 concentration from 1.0% to 20% by monitoring its electrical resistance. Results showed that after several testing cycles the sensor's output becomes stable, and its sensitivity is 0.054 with deviation 2.65 × 10(-4) and hysteresis is 8.5%. Due to its simple fabrication process, the sensor has potential for application in environmental monitoring, where lower power consumption and small size are required.

  16. A Micro Oxygen Sensor Based on a Nano Sol-Gel TiO2 Thin Film

    Directory of Open Access Journals (Sweden)

    Hairong Wang

    2014-09-01

    Full Text Available An oxygen gas microsensor based on nanostructured sol-gel TiO2 thin films with a buried Pd layer was developed on a silicon substrate. The nanostructured titania thin films for O2 sensors were prepared by the sol-gel process and became anatase after heat treatment. A sandwich TiO2 square board with an area of 350 μm × 350 μm was defined by both wet etching and dry etching processes and the wet one was applied in the final process due to its advantages of easy control for the final structure. A pair of 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer was fabricated on the board by a lift-off process. The sensor chip was tested in a furnace with changing the O2 concentration from 1.0% to 20% by monitoring its electrical resistance. Results showed that after several testing cycles the sensor’s output becomes stable, and its sensitivity is 0.054 with deviation 2.65 × 10−4 and hysteresis is 8.5%. Due to its simple fabrication process, the sensor has potential for application in environmental monitoring, where lower power consumption and small size are required.

  17. Synthesis and structural characterization of nano-hydroxyapatite biomaterials prepared by microwave processing

    Science.gov (United States)

    Ramli, Rosmamuhamadani; Arawi, Ainaa Zafirah Omar; Talari, Mahesh Kumar; Mahat, Mohd Muzamir; Jais, Umi Sarah

    2012-07-01

    Synthetic hydroxyapatite, (HA, Ca10(PO4)6(OH)2), is an attractive and widely utilized bio-ceramic material for orthopedic and dental implants because of its close resemblance of native tooth and bone crystal structure. Synthetic HA exhibits excellent osteoconductive properties. Osteoconductivity means the ability to provide the appropriate scaffold or template for bone formation. Calcium phosphate biomaterials [(HA), tri-calcium phosphate (TCP) and biphasic calcium phosphate (HA/TCP)] with appropriate three-dimensional geometry are able to bind and concentrate endogenous bone morphogenetic proteins in circulation, and may become osteoinductive and can be effective carriers of bone cell seeds. This HA can be used in bio-implants as well as drug delivery application due to the unique properties of HA. Biomaterials synthesized from the natural species like mussel shells have additional benefits such as high purity, less expensive and high bio compatibility. In this project, HA-nanoparticles of different crystallite size were prepared by microwave synthesis of precursors. High purity CaO was extracted from the natural mussel shells for the synthesis of nano HA. Dried nano HA powders were analyzed using X-Ray Diffraction (XRD) technique for the determination of crystal structure and impurity content. Scanning Electron Microscopic (SEM) investigation was employed for the morphological investigation of nano HA powders. From the results obtained, it was concluded that by altering the irradiation time, nano HA powders of different crystallite sizes and morphologies could be produced. Crystallite sizes calculated from the XRD patterns are found to be in the range of 10-55 nm depending on the irradiation time.

  18. A Novel Nano-Grating Structure of Polarizing Beam Splitters

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liang; LI Jing; LI Cheng-Fang; ZHANG Fei; SHI Li-Na

    2006-01-01

    @@ A metal wire nanograting is fabricated and used as a polarizing beam splitter that reflects TE polarization and transmits TM polarization. The metal wire nanograting is based on a fully optimized design structure that consists of not only the core nanowire metal grid but also the substrate nanograting. The substrate nanograting is designed to provide better performance for both TM and TE polarizations. We fabricate metal-stripe gratings on a glass substrate using nanoimprint lithography and reactive ion etching process. A detailed investigation of the polarization effect at 1550 nm wavelength is carried out with the theoretical analysis and experimental results.The polarizing beam splitter has uniform performance with wide variations in the incident angle (±25) and has high efficiency for both the reflected and the transmitted beams.

  19. Extracellular matrix structure and nano-mechanics determine megakaryocyte function.

    Science.gov (United States)

    Malara, Alessandro; Gruppi, Cristian; Pallotta, Isabella; Spedden, Elise; Tenni, Ruggero; Raspanti, Mario; Kaplan, David; Tira, Maria Enrica; Staii, Cristian; Balduini, Alessandra

    2011-10-20

    Cell interactions with matrices via specific receptors control many functions, with chemistry, physics, and membrane elasticity as fundamental elements of the processes involved. Little is known about how biochemical and biophysical processes integrate to generate force and, ultimately, to regulate hemopoiesis into the bone marrow-matrix environment. To address this hypothesis, in this work we focus on the regulation of MK development by type I collagen. By atomic force microscopy analysis, we demonstrate that the tensile strength of fibrils in type I collagen structure is a fundamental requirement to regulate cytoskeleton contractility of human MKs through the activation of integrin-α2β1-dependent Rho-ROCK pathway and MLC-2 phosphorylation. Most importantly, this mechanism seemed to mediate MK migration, fibronectin assembly, and platelet formation. On the contrary, a decrease in mechanical tension caused by N-acetylation of lysine side chains in type I collagen completely reverted these processes by preventing fibrillogenesis.

  20. Surface plasmon coupled emission studies on engineered thin film hybrids of nano α−Al{sub 2}O{sub 3} on silver

    Energy Technology Data Exchange (ETDEWEB)

    Mulpur, Pradyumna; Chunduri, Avinash; Rattan, Tanu Mimani; Kamisetti, Venkataramaniah [Department of Physics, Sri Sathya Sai Institute of Higher Learning, Prasanthi Nilayam, Andhra Pradesh, India 515134 (India); Lingam, Kiran; Rao, Apparao M. [Department of Physics and Astronomy, 202C Kinard Laboratory, Clemson University, Clemson, SC 29634 (United States)

    2014-01-28

    We report the first time engineering and fabrication of a novel thin film hybrid of nano α-alumina doped in a polyvinyl alcohol (PVA) matrix along with rhodamine b (Rh.B) on a silver thin film. Silver films of 50 nm thickness on glass slides were fabricated by thermal evaporation. Nano α-alumina was synthesized through the combustion route and characterized by XRD. The α-alumina was dispersed in the PVA-Rh.B matrix by tip sonication. The resultant solution was spin coated on the Ag thin film at 3000 rpm to generate an overcoat of ∼30 nm. We have designed and constructed an opto-mechanical setup for performing the SPCE studies. Excitation with a 532 nm continuous laser, led to the coupling of the energy of Rh.B emission to the surface plasmon modes of silver. The emission @ 580 nm was recorded using an Ocean Optics(copyright, serif) fiber optic spectrometer. Calculation of the ratio of signal intensity between the directional SPCE and isotropic fluorescence gives us the factor of signal enhancements which SPCE offers. We report an '8 fold' signal enhancement attributed to SPCE arising from the metal oxide doped thin film hybrid. We observed only a '5 fold' signal enhancement in the case of a thin film hybrid without α-alumina. The emission was also 92% P-polarized which is in coherence with the theory of SPCE. The greater degree of signal enhancement observed in the α-alumina doped thin film substrate can be attributed to the surface roughness which alumina offers to silver, which along with the porous nature of alumina enables a greater degree of adsorption of Rh.B which results in a higher emission intensity. Computational modeling was also performed, based on surface plasmon resonance (SPR) calculations to provide theoretical background to observed experimental data. The α-alumina thin film hybrid can be extended as an economical sensing platform towards the high sensitive detection of analytes.

  1. Assembly and structural analysis of a covalently closed nano-scale DNA cage

    DEFF Research Database (Denmark)

    Andersen, Felicie F; Knudsen, Bjarne; Oliveira, Cristiano Luis Pinto De

    2008-01-01

     The inherent properties of DNA as a stable polymer with unique affinity for partner molecules determined by the specific Watson-Crick base pairing makes it an ideal component in self-assembling structures. This has been exploited for decades in the design of a variety of artificial substrates...... be described as a nano-scale DNA cage, Hence, in theory it could hold proteins or other bio-molecules to enable their investigation in certain harmful environments or even allow their organization into higher order structures...

  2. Improvement of replication fidelity in injection moulding of nano structures using an induction heating system

    DEFF Research Database (Denmark)

    Menotti, Stefano; Hansen, Hans Nørgaard; Bissacco, Giuliano

    2014-01-01

    In today’s industry, applications involving surface pattering with sub-μm scale structures have shown a high interest. The replication of these structures by injection molding leads to special requirements for the mold in order to ensure proper replication and an acceptable cycle time. A tool...... quantitatively characterized by atomic force microscopy comparing the measurement in the nickel insert with the corresponding polymer nano-features. The experimental results show that the use of the induction heating system is an efficient way to improve the pattern replication....

  3. Controllable Direct-Writing of Serpentine Micro/Nano Structures via Low Voltage Electrospinning

    Directory of Open Access Journals (Sweden)

    Feiyu Fang

    2015-08-01

    Full Text Available Micro/nanofibers prepared by direct-writing using an electrospinning (ES technique have drawn more attention recently owing to their intriguing physical properties and great potential as building blocks for micro/nanoscale devices. In this work, a wavy direct-writing (WDW process was developed to directly write serpentine micro/nano structures suitable for the fabrication of micro devices. This fabrication ability will realize the application of electrospun-nanofiber-based wiring of structural and functional components in microelectronics, MEMS, sensor, and micro optoelectronics devices, and, especially, paves the way for the application of electrospinning in printing serpentine interconnector of large-area organic stretchable electronics.

  4. Improvement of replication fidelity in injection moulding of nano structures using an induction heating system

    DEFF Research Database (Denmark)

    Menotti, Stefano; Hansen, Hans Nørgaard; Bissacco, Giuliano

    2014-01-01

    In today’s industry, applications involving surface pattering with sub-μm scale structures have shown a high interest. The replication of these structures by injection molding leads to special requirements for the mold in order to ensure proper replication and an acceptable cycle time. A tool ins...... quantitatively characterized by atomic force microscopy comparing the measurement in the nickel insert with the corresponding polymer nano-features. The experimental results show that the use of the induction heating system is an efficient way to improve the pattern replication....

  5. Characterization of nano structured metallic materials; Caracterizacion de materiales metalicos nanoestructurados

    Energy Technology Data Exchange (ETDEWEB)

    Marin A, M.; Gutierrez W, C.; Cruz C, R.; Angeles C, C. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    Nowadays the search of new materials with specific optical properties has carried out to realize a series of experiments through the polymer synthesis [(C{sub 3}N{sub 3}){sub 2} (NH){sub 3}]{sub n} doped with gold metallic nanoparticles. The thermal stability of a polymer is due to the presence of tyazine rings contained in the structure. The samples were characterized by High Resolution Transmission Electron Microscopy, X-ray diffraction by the Powder method, Ft-infrared and its thermal properties by Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA). One of the purposes of this work is to obtain nano structured materials over a polymeric matrix. (Author)

  6. Structural and mechanical properties of nano-crystal TiN coatings

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Chenhui; PAN; Guoshun; LUO; Jianbin; LI; Wenzhi; CH

    2004-01-01

    The structural and mechanical properties of TiN coatings prepared by ion beam assisted deposition (IBAD) were studied. The coatings have a polycrystal structure with grain size of ~10 nm or less. The hardness of the coatings increases with increasing grain size of TiN crystallites. The coating with grain size of 10.3 nm even has a superhardness of 44.7GPa. The relationship between the hardness and the grain size in the nano-crystalline coatings was discussed on the basis of grain-boundary triple junctions.

  7. Understanding the Structure of Amorphous Thin Film Hafnia - Final Paper

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Andre [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-27

    Hafnium Oxide (HfO2) amorphous thin films are being used as gate oxides in transistors because of their high dielectric constant (κ) over Silicon Dioxide. The present study looks to find the atomic structure of HfO2 thin films which hasn’t been done with the technique of this study. In this study, two HfO2 samples were studied. One sample was made with thermal atomic layer deposition (ALD) on top of a Chromium and Gold layer on a silicon wafer. The second sample was made with plasma ALD on top of a Chromium and Gold layer on a Silicon wafer. Both films were deposited at a thickness of 50nm. To obtain atomic structure information, Grazing Incidence X-ray diffraction (GIXRD) was carried out on the HfO2 samples. Because of this, absorption, footprint, polarization, and dead time corrections were applied to the scattering intensity data collected. The scattering curves displayed a difference in structure between the ALD processes. The plasma ALD sample showed the broad peak characteristic of an amorphous structure whereas the thermal ALD sample showed an amorphous structure with characteristics of crystalline materials. This appears to suggest that the thermal process results in a mostly amorphous material with crystallites within. Further, the scattering intensity data was used to calculate a pair distribution function (PDF) to show more atomic structure. The PDF showed atom distances in the plasma ALD sample had structure up to 10 Å, while the thermal ALD sample showed the same structure below 10 Å. This structure that shows up below 10 Å matches the bond distances of HfO2 published in literature. The PDF for the thermal ALD sample also showed peaks up to 20 Å, suggesting repeating atomic spacing outside the HfO2 molecule in the sample. This appears to suggest that there is some crystalline structure within the thermal ALD sample.

  8. Structure of ductile iron in thin walled castings

    Directory of Open Access Journals (Sweden)

    M. Górny

    2007-12-01

    Full Text Available It this work it has been shown that it is possible to produce thin wall ductile iron (TWDI castings with considerably length using Archimedes spiral with wall thickness of 1, 2 and 3 mm. Inmould technique was used to produce TWDI. It has been estimated castability and metallographic investigations were made using different moulding materials. From castability measurements result that it is possible to obtain thin wall ductile iron castings with wall thickness down to 1 mm with castability of 200 mm. Using mould with small ability to absorb heat castability increases twice. At wall thickness equal 3 mm castability reaches 1000 mm and using LDASC sand its value increases to over 1500 mm. Structure parameters for different wall thickness and moulding materials (graphite nodule count, ferrite and cementite fraction are plotted versus distance from the beginning of spiral. It is shown strong influence of LDASC sand (material with small ability to absorb heat on structure parameters (NF, Vf i VC revealing gradient character of TWDI.

  9. Nano-based sensor for assessment of weaponry structural degradation

    Science.gov (United States)

    Brantley, Christina L.; Edwards, Eugene; Ruffin, Paul B.; Kranz, Michael

    2016-04-01

    Missiles and weaponry-based systems are composed of metal structures that can degrade after prolonged exposure to environmental elements. A particular concern is accumulation of corrosion that generally results from prolonged environmental exposure. Corrosion, defined as the unintended destruction or deterioration of a material due to its interaction with the environment, can negatively affect both equipment and infrastructure. System readiness and safety can be reduced if corrosion is not detected, prevented and managed. The current corrosion recognition methods (Visual, Radiography, Ultrasonics, Eddy Current, and Thermography) are expensive and potentially unreliable. Visual perception is the most commonly used method for determining corrosion in metal. Utilization of an inductance-based sensor system is being proposed as part of the authors' research. Results from this research will provide a more efficient, economical, and non-destructive sensing approach. Preliminary results demonstrate a highly linear degradation within a corrosive environment due to the increased surface area available on the sensor coupon. The inductance of the devices, which represents a volume property of the coupon, demonstrated sensitivity to corrosion levels. The proposed approach allows a direct mass-loss measurement based on the change in the inductance of the coupon when placed in an alternating magnetic field. Prototype devices have demonstrated highly predictable corrosion rates that are easily measured using low-power small electronic circuits and energy harvesting methods to interrogate the sensor. Preliminary testing demonstrates that the device concept is acceptable and future opportunities for use in low power embedded applications are achievable. Key results in this paper include the assessment of typical Army corrosion cost, degradation patterns of varying metal materials, and application of wireless sensors elements.

  10. Structure and Thermal Stability of Copper Nitride Thin Films

    Directory of Open Access Journals (Sweden)

    Guangan Zhang

    2013-01-01

    Full Text Available Copper nitride (Cu3N thin films were deposited on glass via DC reactive magnetron sputtering at various N2 flow rates and partial pressures with 150°C substrate temperature. X-ray diffraction and scanning electron microscopy were used to characterize the microstructure and morphology. The results show that the films are composed of Cu3N crystallites with anti-ReO3 structure. The microstructure and morphology of the Cu3N film strongly depend on the N2 flow rate and partial pressure. The cross-sectional micrograph of the film shows typical columnar, compact structure. The thermal stabilities of the films were investigated using vacuum annealing under different temperature. The results show that the introducing of argon in the sputtering process decreases the thermal stability of the films.

  11. Chip-package nano-structured copper and nickel interconnections with metallic and polymeric bonding interfaces

    Science.gov (United States)

    Aggarwal, Ankur

    developed to address the IC packaging requirements beyond the ITRS projections and to introduce innovative design and fabrication concepts that will further advance the performance of the chip, the package, and the system board. The nano-structured interconnect technology simultaneously packages all the ICs intact in wafer form with quantum jump in the number of interconnections with the lowest electrical parasitics. The intrinsic properties of nano materials also enable several orders of magnitude higher interconnect densities with the best mechanical properties for the highest reliability and yet provide higher current and heat transfer densities. Nano-structured interconnects provides the ability to assemble the packaged parts on the system board without the use of underfill materials and to enable advanced analog/digital testing, reliability testing, and burn-in at wafer level. This thesis investigates the electrical and mechanical performance of nanostructured interconnections through modeling and test vehicle fabrication. The analytical models evaluate the performance improvements over solder and compliant interconnections. Test vehicles with nano-interconnections were fabricated using low cost electro-deposition techniques and assembled with various bonding interfaces. Interconnections were fabricated at 200 micron pitch to compare with the existing solder joints and at 50 micron pitch to demonstrate fabrication processes at fine pitches. Experimental and modeling results show that the proposed nano-interconnections could enhance the reliability and potentially meet all the system performance requirements for the emerging micro/nano-systems.

  12. Optical properties of the micro/nano structures of Morpho butterfly wing scales

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The micro/nano structures of the wing scales in Morpho butterfly are responsible for the structural coloration,with a major part ascribed to interference and diffraction of light.The optical properties of the butterfly wings were investigated by simulating a two-dimensional model using rigorous coupled-wave analysis technique.It is proved that they depend strongly on the structural parameters,incidence angle and refractive index.The peak value and the peak wavelength of the reflection efficiency increase as the vertical periodic thickness increases.The peak value decreases observably,while both of the bandwidth and the peak wavelength increase when the number of the vertical periods decreases.Increase of the horizontal periodic width causes a decrease of the peak value and an increase of the peak wavelength,although the variations are small.The peak value decreases distinctly and the peak wavelength increases as the ambient refractive index increases,which corresponds to the variation in ambient conditions.The research reveals the mechanisms of the brilliant structural color in Morpho butterfly,and is of great significance to the design,manufacture and applications of the bionic micro/nano structures for gas detection.

  13. Grazing Processes and the Structure and Persistence of Thin Biological Layers

    Science.gov (United States)

    1999-09-30

    technique and subsequent capture onto a black Nuclepore filter for epifluorescence microscopy preserves the colony’s gelatinous matrix. We are able to...However, the diatom’s gelatinous matrix is not preserved in aldehyde, preventing adequate processing of this important species in those samples. Obtaining...growth and loss) in and around thin layers and the first cm-scale profiles of nano- and micro- plankton collected in a layered coastal water column

  14. Nano-micro structured superhydrophobic zinc coating on steel for prevention of corrosion and ice adhesion.

    Science.gov (United States)

    Brassard, J D; Sarkar, D K; Perron, J; Audibert-Hayet, A; Melot, D

    2015-06-01

    Thin films of zinc have been deposited on steel substrates by electrodeposition process and further functionalized with ultra-thin films of commercial silicone rubber, in order to obtain superhydrophobic properties. Morphological feature, by scanning electron microscope (SEM), shows that the electrodeposited zinc films are composed of micro-nano rough patterns. Furthermore, chemical compositions of these films have been analyzed by X-ray diffraction (XRD) and infra-red (IRRAS). An optimum electrodeposition condition, based on electrical potential and deposition time, has been obtained which provides superhydrophobic properties with a water contact angle of 155±1°. The corrosion resistance properties, in artificial seawater, of the superhydrophobic zinc coated steel are found to be superior to bare steel. Similarly, the measured ice adhesion strength on superhydrophobic surfaces, using the centrifugal adhesion test (CAT), is found to be 6.3 times lower as compared to bare steel. This coating has promising applications in offshore environment, to mitigate corrosion and reduce ice adhesion. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. 17.6%-Efficient radial junction solar cells using silicon nano/micro hybrid structures

    Science.gov (United States)

    Lee, Kangmin; Hwang, Inchan; Kim, Namwoo; Choi, Deokjae; Um, Han-Don; Kim, Seungchul; Seo, Kwanyong

    2016-07-01

    We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm2 exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm-2 because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the proposed hybrid structure to become a foundational technology for the development of highly efficient radial junction solar cells.We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm2 exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm-2 because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the

  16. Atomic structure and thermal stability of interfaces between metallic glass and embedding nano-crystallites revealed by molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Gao, X.Z.; Yang, G.Q.; Xu, B.; Qi, C.; Kong, L.T., E-mail: konglt@sjtu.edu.cn; Li, J.F.

    2015-10-25

    Molecular dynamics simulations were performed to investigate the atomic structure and thermal stability of interfaces formed between amorphous Cu{sub 50}Zr{sub 50} matrix and embedding B2 CuZr nano-crystallites. The interfaces are found to be rather abrupt, and their widths show negligible dependence on the nano-crystallite size. Local atomic configuration in the interfacial region is dominated by geometry characterized by Voronoi polyhedra <0,5,2,6> and <0,4,4,6>, and the contents of these polyhedra also exhibit apparent size dependence, which in turn results in an increasing trend in the interfacial energy against the nano-crystallite size. Annealing of the interface models at elevated temperatures will also enrich these characterizing polyhedra. While when the temperature is as high as the glass transition temperature of the matrix, growth of the nano-crystallites will be appreciable. The growth activation energy also shows size dependence, which is lower for larger nano-crystallites, suggesting that large nano-crystallites are prone to grow upon thermal disturbance. - Highlights: • Special clusters characterizing the local geometry are abundant in the interfaces. • Their content varies with the size of the embedding nano-crystallite. • In turn, size dependences in interfacial thermodynamics and kinetics are observed.

  17. Novel low cost standardized Nano-Satellite structure bus for LEO missions

    Science.gov (United States)

    Anubhav, T.; Sarwesh, P.; Narayan, V.; Varma, P. A.; Prasad, R. A.; Loganathan, M.; Rao, D. N.; Sriram, S.; Venkatesh, M.

    This paper focuses on SRMSAT STRUCTURE BUS which is a standardized Nano-Satellite structure bus. It provides a standard platform for a wide variety of missions in LEO and can be realized in a very short developmental period. The bus was designed and developed for SRMSAT, the SRM University (Sri Ramaswamy Memorial University) student Nano-Satellite, by the undergraduate students and faculty of SRM University in collaboration with Indian Space Research Organization (ISRO). The bus can support payloads up to a mass of 20kg. SRMSAT STRUCTURE BUS has a mass of around 6 kg and dimensions 280mm × 280mm × 280mm with an available volume of 11000 cc. Vibration Testing of the bus has been performed upto 6.7 gRMS. This makes the satellite capable of being launched by any launch vehicle in the world. An innovative PCB mounting design has been introduced in this structure bus which facilitates mounting of a maximum 7 PCB trays independently, each tray capable of holding a 250 mm2 PCB. Structural analysis of SRMSAT STRUCTURE BUS was done using NX Nastran. The boundary conditions for each analysis were defined based on the loading conditions as specified by the launcher, PSLV (Polar Satellite Launch Vehicle). Optimization of each individual component was performed by maintaining a minimum threshold between the local frequencies of the component and global frequencies of the entire satellite. Static, Modal, Harmonic and Random Vibration analysis of the structure bus was performed. This paper also describes the methodology followed in the static and dynamic analysis of the structure bus to finalize the design. The results have been tested and validated at ISRO Satellite Centre, Bangalore with around 90% accuracy and the structure has been certified as a standard structure bus for Nano-satellite missions. In terms of expandability, this structure bus is capable of accommodating deployable solar panels. Also, the payload mounting is not only restricted to th- bottom deck but can

  18. Controlled growth of organic nanofibers on nano- and micro-structured gold surfaces

    Science.gov (United States)

    Madsen, Morten; de Oliveira Hansen, Roana M.; Kjelstrup-Hansen, Jakob; Rubahn, Horst-Günter

    2009-08-01

    Nanofibers made from para-hexaphenylene (p6P) molecules hold unique optoelectronic properties, which make them interesting candidates as elements in electronic and optoelectronic devices. Typically these nanofibers are grown on specific single-crystalline substrates, on which long, mutually parallel nanofibers are formed. However, the lack of ability to further process these substrates restrains their use in devices. In this work, a novel method for in-situ growth of p6P nanofibers on nano- and micro-structured gold surfaces is presented. The substrates are prepared by conventional microfabrication techniques such as lithography, etching and metal deposition, which increase their potential as device platforms. The results presented here demonstrate, that both the growth direction and the nanofiber length can be controlled by placement of nano- and micro-structured lines on the substrate. It is shown that the preferred growth direction of the nanofibers is perpendicular to these structures whereas their length scales are limited by the size and placement of the structures. This work therefore demonstrates a new technique, which can be useful within future organic nanofiber based applications.

  19. Femtosecond laser surface structuring of molybdenum thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kotsedi, L., E-mail: Kotsedi@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Mthunzi, P. [Council for Scientific and Industrial Research (CSIR), Biophotonics Lab: National Laser Centre Pretoria, 0001 (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70/3, 20133 Milano, Itala (Italy); Sechoghela, P.; Mongwaketsi, N. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Ramponi, R. [Institute for Photonics and Nanotechnologies (IFN)–CNR, Piazza Leanardo Da Vinci, 32, 20133 Milano (Italy); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa)

    2015-10-30

    Highlights: • Color change of the molybdenum thin film from shinny to violet–yellowish color after laser irradiation at various laser powers. • Formation of the molybdenum dioxide coating after laser exposure, as confirmed by the X-ray diffraction spectrometry. • Selective solar absorbing nature of the laser exposed films. • Study of the binding energies is presented in this contribution using the XPS spectrometry. - Abstract: This contribution reports on the femtosecond surface structuring of molybdenum thin coatings deposited by electron beam evaporation onto Corning glass substrates. The 1-D type periodic grating lines created by such an ablation showed that the widths of the shallow grooves followed a logarithmic dependence with the laser energy incident on the molybdenum film. The electronic valence “x” of the created oxide surface layer MoO{sub x} was found to be incident laser power dependent via Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy and X-ray diffraction investigations. Such a photo-induced MoO{sub x}–Mo nanocomposite exhibited effective selective solar absorption in the UV–vis–IR spectral range.

  20. Structure and magnetic properties of thin films and superlattices

    CERN Document Server

    Bentall, M J

    2002-01-01

    Thin layers of rare earth elements and Laves phase superlattices were grown using molecular beam epitaxy. Their structure and magnetic properties have been probed using x-ray and neutron scattering, magnetisation measurements and high resolution electron microscopy. When holmium is grown on yttrium, the x-ray scattering from layers with a thickness below T sub c ' 115 A is characteristic of a pseudomorphic layer with the same in-plane lattice parameter as the yttrium substrate to within 0.05%. For layers above T sub c ' there is a sharp reduction in misfit strain which is probably due to the creation of edge dislocations. When gadolinium is grown on yttrium, no sharp change of strain of the thin layer was observed up to a thickness of 2920 A. This is characteristic of a pseudomorphic layer, and a failure to nucleate dislocations. For the Laves phase superlattices, a study of the x-ray scattering near several Bragg reflections revealed the presence of numerous superlattice peaks, showing that the samples exhib...

  1. Dynamics and structure formation in thin polymer melt films

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, Ralf [Max-Planck-Institut for Dynamics and Self-Organization, Bunsenstrasse 10, 37073 Goettingen (Germany); Herminghaus, Stephan [Max-Planck-Institut for Dynamics and Self-Organization, Bunsenstrasse 10, 37073 Goettingen (Germany); Neto, Chiara [Department of Applied Mathematics, Australian National University, Canberra ACT 0200 (Australia); Schlagowski, Stefan [Department of Applied Physics, University of Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany); Podzimek, Daniel [Experimental Physics, Saarland University, 66041 Saarbruecken (Germany); Konrad, Renate [Experimental Physics, Saarland University, 66041 Saarbruecken (Germany); Mantz, Hubert [Experimental Physics, Saarland University, 66041 Saarbruecken (Germany); Jacobs, Karin [Experimental Physics, Saarland University, 66041 Saarbruecken (Germany)

    2005-03-09

    The stability of thin liquid coatings plays a fundamental role in everyday life. We studied the stability conditions of thin (3 to 300 nm) liquid polymer films on various substrates. The key role is played by the effective interface potential {phi} of the system air/film/substrate, which determines the dewetting scenario in case the film is not stable. We describe in this study how to distinguish a spinodal dewetting scenario from heterogeneous and homogeneous dewetting by analysing the emerging structures of the film surface by e.g. Minkowski measures. We also include line tension studies of tiny droplets, showing that the long-range part of {phi} does affect the drop profile, but only very close to the three phase boundary line. The dynamic properties of the films are characterized via various experimental methods: the form of the dewetting front, for example, was recorded by scanning probe microscopy and gives insight into the boundary condition between the liquid and the substrate. We further report experiments probing the viscosity and the glass transition temperature of nm-thick films using e.g. ellipsometry. Here we find that even short-chained polymer melts exhibit a significant reduction of the glass transition temperature as the film thickness is reduced below 100 nm.

  2. Active stabilization of thin-wall structures under compressive loading

    Science.gov (United States)

    Welham, Jared; Calius, Emilio P.; Chase, J. Geoffrey

    2003-08-01

    The active suppression of elastic buckling instability has the potential to significantly increase the effective strength of thin-wall structures. Despite all the interest in smart structures, the active suppression of buckling has received comparatively little attention. This paper addresses the effects of embedded actuation on the compression buckling strength of laminated composite plates through analysis and simulation. Numerical models are formulated that include the influence of essential features such as sensor uncertainty and noise, actuator saturation and control architecture on the buckling process. Silicon-based strain sensors and diffuse laser distance sensors are both considered for use in the detection of incipient buckling behavior due to their increased sensitivity. Actuation is provided by paired distributions of piezo-electric material incorporated into both sides of the laminate. Optimal controllers are designed to command the structure to deform in ways that interfere with the development of buckling mode shapes. Commercial software packages are used to solve the resulting non-linear equations, and some of the tradeoffs are enumerated. Overall, the results show that active buckling control can considerably enhance resistance to instability under compressive loads. These buckling load predictions demonstrate the viability of optimal control and piezo-electric actuation for implementing active buckling control. Due to the importance of early detection, the relative effectiveness of active buckling control is shown to be strongly dependent on the performance of the sensing scheme, as well as on the characteristics of the structure.

  3. Density functional theory for field emission from carbon nano-structures.

    Science.gov (United States)

    Li, Zhibing

    2015-12-01

    Electron field emission is understood as a quantum mechanical many-body problem in which an electronic quasi-particle of the emitter is converted into an electron in vacuum. Fundamental concepts of field emission, such as the field enhancement factor, work-function, edge barrier and emission current density, will be investigated, using carbon nanotubes and graphene as examples. A multi-scale algorithm basing on density functional theory is introduced. We will argue that such a first principle approach is necessary and appropriate for field emission of nano-structures, not only for a more accurate quantitative description, but, more importantly, for deeper insight into field emission.

  4. Handbook of damage mechanics nano to macro scale for materials and structures

    CERN Document Server

    2015-01-01

    This authoritative reference provides comprehensive coverage of the topics of damage and healing mechanics. Computational modeling of constitutive equations is provided as well as solved examples in engineering applications. A wide range of materials that engineers may encounter are covered, including metals, composites, ceramics, polymers, biomaterials, and nanomaterials. The internationally recognized team of contributors employ a consistent and systematic approach, offering readers a user-friendly reference that is ideal for frequent consultation. Handbook of Damage Mechanics: Nano to Macro Scale for Materials and Structures is ideal for graduate students and faculty, researchers, and professionals in the fields of Mechanical Engineering, Civil Engineering, Aerospace Engineering, Materials Science, and Engineering Mechanics.

  5. Energy loss to intravalley acoustic modes in nano-dimensional wire structures at low temperatures

    Science.gov (United States)

    Nag, S.; Das, B.; Basu, A.; Das, J.; Bhattacharya, D. P.; Sarkar, C. K.

    2017-03-01

    The theory of rate of loss of energy of non-equilibrium electrons due to inelastic interaction with the intravalley acoustic phonons in a nano-dimensional semiconductor wire has been developed under the condition of low lattice temperature, when the approximations of the well known traditional theory are not valid. Numerical results are obtained for narrow-channel GaAs-GaAlAs wires structures. On comparison with other available results it is revealed that the finite energy of the intravalley acoustic phonons and, the use of the full form of the phonon distribution without truncation to the equipartition law, produce significant changes in the energy loss characteristics at low temperatures.

  6. Nano-scale structure in membranes in relation to enzyme action - computer simulation vs. experiment

    DEFF Research Database (Denmark)

    Høyrup, P.; Jørgensen, Kent; Mouritsen, O.G.

    2002-01-01

    There is increasing theoretical and experimental evidence indicating that small-scale domain structure and dynamical heterogeneity develop in lipid membranes as a consequence of the the underlying phase transitions and the associated density and composition fluctuations. The relevant coherence le...... mixtures show that the enzyme activity is modulated by nano-scale lipid-domain formation in the lipid bilayer and lead to a characteristic lag-burst behavior. The simulations are found to be in semi-quantitative agreement with experimental data....

  7. Characterizing the structure of topological insulator thin films

    Energy Technology Data Exchange (ETDEWEB)

    Richardella, Anthony; Kandala, Abhinav; Lee, Joon Sue; Samarth, Nitin [Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-08-01

    We describe the characterization of structural defects that occur during molecular beam epitaxy of topological insulator thin films on commonly used substrates. Twinned domains are ubiquitous but can be reduced by growth on smooth InP (111)A substrates, depending on details of the oxide desorption. Even with a low density of twins, the lattice mismatch between (Bi, Sb){sub 2}Te{sub 3} and InP can cause tilts in the film with respect to the substrate. We also briefly discuss transport in simultaneously top and back electrically gated devices using SrTiO{sub 3} and the use of capping layers to protect topological insulator films from oxidation and exposure.

  8. Characterizing the structure of topological insulator thin films

    Directory of Open Access Journals (Sweden)

    Anthony Richardella

    2015-08-01

    Full Text Available We describe the characterization of structural defects that occur during molecular beam epitaxy of topological insulator thin films on commonly used substrates. Twinned domains are ubiquitous but can be reduced by growth on smooth InP (111A substrates, depending on details of the oxide desorption. Even with a low density of twins, the lattice mismatch between (Bi, Sb2Te3 and InP can cause tilts in the film with respect to the substrate. We also briefly discuss transport in simultaneously top and back electrically gated devices using SrTiO3 and the use of capping layers to protect topological insulator films from oxidation and exposure.

  9. Thermomagnetic writing in thin Co/Pt layered structures

    Science.gov (United States)

    Greidanus, F. J. A. M.; Zeper, W. B.; den Broeder, F. J. A.; Godlieb, W. F.; Carcia, P. F.

    1989-06-01

    In this letter we demonstrate thermomagnetic writing in a Co/Pt thin-film layered structure or multilayer: 25×(4.1 Å Co+19 Å Pt). This film exhibits perpendicular magnetic anisotropy, 100% remanence, and a coercive field of 76 kA/m at room temperature. The coercive field is a strong function of temperature and decreases to zero at 250 °C. In this layered film regular domains can be written with low applied fields (below 50 kA/m) and the writing threshold is about 4 mW. Their good magnetic and magneto-optical properties together with their high corrosion resistance make these layers promising candidates for magneto-optical recording.

  10. Ionization Modeling Astrophysical Gaseous Structures. I. The Optically Thin Regime

    CERN Document Server

    Churchill, Christopher W; Medina, Amber; Vliet, Jacob R Vander

    2014-01-01

    We present a code for modelling the ionization conditions of optically thin astrophysical gas structures. Given the gas hydrogen density, equilibrium temperature, elemental abundances, and the ionizing spectrum, the code solves the equilibrium ionization fractions and number densities for all ions from hydrogen to zinc. The included processes are photoionization, Auger ionization, direct collisional ionization, excitation auto-ionization, charge exchange ionization, two-body radiative recombination, dielectronic recombination, and charge exchange recombination. The ionizing spectrum can be generalized to include the ultraviolet background (UVB) and/or Starburst99 stellar populations of various masses, ages, metallicities, and distances. The ultimate goal with the code is to provide fast computation of the ionization conditions of gas in N-body + hydrodynamics cosmological simulations, in particular adaptive mesh refinement codes, in order to facilitate absorption line analysis of the simulated gas for compari...

  11. Structural mechanics and helical geometry of thin elastic composites.

    Science.gov (United States)

    Wada, Hirofumi

    2016-09-21

    Helices are ubiquitous in nature, and helical shape transition is often observed in residually stressed bodies, such as composites, wherein materials with different mechanical properties are glued firmly together to form a whole body. Inspired by a variety of biological examples, the basic physical mechanism responsible for the emergence of twisting and bending in such thin composite structures has been extensively studied. Here, we propose a simplified analytical model wherein a slender membrane tube undergoes a helical transition driven by the contraction of an elastic ribbon bound to the membrane surface. We analytically predict the curvature and twist of an emergent helix as functions of differential strains and elastic moduli, which are confirmed by our numerical simulations. Our results may help understand shapes observed in different biological systems, such as spiral bacteria, and could be applied to novel designs of soft machines and robots.

  12. A novel nano-sulfur/polypyrrole/graphene nanocomposite cathode with a dual-layered structure for lithium rechargeable batteries

    Science.gov (United States)

    Zhang, Yongguang; Zhao, Yan; Konarov, Aishuak; Gosselink, Denise; Soboleski, Hayden Greentree; Chen, P.

    2013-11-01

    A method for synthesizing nano-sulfur/polypyrrole/graphene nanosheet (nano-S/PPy/GNS) ternary composite with a dual-layered structure is described. By taking advantage of both capillary force driven self-assembly of polypyrrole on graphene nanosheets and adhesion ability of polypyrrole to sulfur, we develop a stable and ordered nano-S/PPy/GNS composite cathode for lithium/sulfur (Li/S) batteries. The high dispersion of nanoscopic sulfur on the surface of PPy/GNS composite and good electrical conductivity of GNS seems to benefit the sulfur utilization and the reactivity of the composite. Furthermore, PPy plays an important role in retarding diffusion of polysulfides out of the electrode. The resulting nano-S/PPy/GNS composite cathode delivers a high initial capacity of 1415.7 mAh g-1, remaining a reversible capacity of 641.5 mAh g-1 after 40 cycles at 0.1 C rate.

  13. Feasibility study of SWIR light absorption enhancement in PbS and PbSe nano-structure layers using surface plasmon polariton

    Directory of Open Access Journals (Sweden)

    Nimrod Nissim

    2017-03-01

    Full Text Available We present a theoretical feasibility study of the use of reflection grating couplers in order to harness the Surface Plasmon Polariton (SPP to increase the absorption efficiency in the short wavelength infrared (SWIR spectral range of a novel SWIR to visible (VIS direct up-conversion imaging device. This device detects the SWIR spectral band photons using high absorption PbSe/CdSe core-shell, PbS nano-spheres or PbSe nano-columns. In order to further enhance the absorption of the SWIR light within the nano-structure layer we propose to add another light absorption enhancement, known as SPP enhanced absorption. The idea is to cover the absorber layer surface with a structured metal layer that will ignite SPPs on the metal – dielectric interface, by coupling between the incident TM polarized photons and the SPP modes; this results in better field confinement at the interface that will further increase the SWIR absorption of this thin layer. Calculation of the field profile of the surface plasmon (SP in the SWIR range shows perpendicular dominance of the SP’s electrical field direction on the dielectric layer side (the PbS or PbSe/CdSe absorption layer side. Based on this result, it was found that, due to the use of quantum confined and, thus, high oscillator strength nanostructures, there is only a marginal increase in the absorption and, hence, in the quantum efficiency when using the SPP enhancement technique. Nevertheless, we show that one of the proposed configurations of the metal grating coupler, having a lamellar structure with a pitch of 1.38μm, a duty cycle (DC of 0.12μm and a height of 60nm, is predicted to increase the total layer’s absorption by 9.5%, mainly due to efficient light scattering rather than to SPP enhanced absorption.

  14. Condensation heat transfer on micro and nano structured super hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Donghyun; Hwang, Kyung Won; Park, Hyun Sun; Kim, Moo Hwan [POSTECH, Pohang (Korea, Republic of)

    2014-05-15

    Condensation phenomena occur during the PCCS operation cooling the containment through phase change heat transfer. Accordingly it is important to enhance the condensation heat transfer performance. Condensation mode is commonly classified as filmwise condensation (FWC) and dropwise condensation (DWC). DWC heat transfer performance has an order of magnitude higher than FWC heat transfer performance. In DWC process, condensed liquid droplets attach to the surface and prevent transfer of heat to the cooled surface. Generally the condensate is removed by gravity. When removal rate of condensate is high, DWC heat transfer performance will be enhanced. In terms of removal rate, superhydrophobic surface, which is recently in the spotlight, is expected to have capability to enhance the DWC heat transfer efficiency by reducing droplet size. In this study, we investigated condensation heat transfer performance on micro and nano structured superhydrophobic surface. Condensation experiments on the micro and nano structured superhydrophobic surface were carried out and compared with those on the smooth hydrophobic surface in terms of heat transfer performance and condensed droplet morphologies. Through the experiments, we found that superhydrophobicity disappeared under the condensation circumstance. As a result, heat transfer performance on the superhydro-phobic structured surface decreased compared with that on the smooth hydrophobic surface. In order to enhance the condensation heat transfer performance with superhydrophobic property, condensation mechanism on superhydrophobic surface and the conditions for sustaining superhydrophobicity should be studied more.

  15. 仿生纳米减反结构的制备%Fabrication of Biomimetic Antireflective Nano Structures

    Institute of Scientific and Technical Information of China (English)

    李腾; 丁剑; 范同祥

    2012-01-01

    The mechanism, fabrication and the reduction of reflection achieved of four types of bioinspired antireflective structures, namely the ordered nano array, the inordered nano structure, the hierarchical nano structure and the butterfly scale structure,are reviewed. The possible way of further research with the combination of computer simulation and optimization as well as the improvement of fabrication process is proposed.%综述了有序纳米阵列、无序纳米结构、分级纳米结构和蝶翅鳞片结构4类结构的减反机理、制备方法以及实现的性能,并提出计算模拟优化与制备工艺改进的结合是进一步研究的思路.

  16. Fabrication of periodical surface structures by picosecond laser irradiation of carbon thin films: transformation of amorphous carbon in nanographite

    Science.gov (United States)

    Popescu, C.; Dorcioman, G.; Bita, B.; Besleaga, C.; Zgura, I.; Himcinschi, C.; Popescu, A. C.

    2016-12-01

    Thin films of carbon were synthesized by ns pulsed laser deposition in vacuum on silicon substrates, starting from graphite targets. Further on, the films were irradiated with a picosecond laser source emitting in visible at 532 nm. After tuning of laser parameters, we obtained a film surface covered by laser induced periodical surface structures (LIPSS). They were investigated by optical, scanning electron and atomic force microscopy. It was observed that changing the irradiation angle influences the LIPSS covered area. At high magnification it was revealed that the LIPSS pattern was quite complex, being composed of other small LIPSS islands, interconnected by bridges of nanoparticles. Raman spectra for the non-irradiated carbon films were typical for a-C type of diamond-like carbon, while the LIPSS spectra were characteristic to nano-graphite. The pristine carbon film was hydrophilic, while the LIPSS covered film surface was hydrophobic.

  17. Dynamic characterization of thin-film inflatable structures

    Science.gov (United States)

    Slade, Kara Nicole

    Inflatable structures constructed from thin polyimide films form a key part of several technology development programs for solar thermal propulsion for satellites, as well as for other applications both in space and on earth. This project investigates the mechanical properties of several of these structures, focusing primarily on their dynamic behavior. The primary focus is the Shooting Star Experiment prototype developed by NASA, but a simpler cylindrical structure is also considered in order to provide an analytically tractable situation for the evaluation of testing and modeling techniques. The cylindrical strut is tested statically to determine its load-deflection characteristics both in linear and nonlinear regimes. The phenomenon of wrinkling is observed under large deflection conditions, particularly at lower pressure. Then, modal testing is used to determine the dynamic properties of the strut for comparison to numerical models. Modal testing is also conducted on Pathfinder 3, a prototype inflatable solar concentrator for the Shooting Star Experiment, both in vacuum and ambient atmospheric conditions. The orbital terminator crossing test is used to determine the dynamic susceptibility of the Pathfinder 3 structure to thermal shock, and it is found to undergo only quasistatic deformations. Finite element models of the cylinder and the Pathfinder 3 concentrator are then constructed using MSC NASTRAN. The inflatable cylinder may be modeled as a beam if only global bending is considered. This restriction leads to the development of a frequency-dependent modulus of elasticity in bending for the structure, developed from engineering beam theory. Both frequency-dependent beam models and shell models are constructed and evaluated for their efficacy. The results from the modeling of the strut are then applied to the inflatable concentrator, where it is found that the shell model captures more of the dynamic subtleties of the system than the beam model, but that both

  18. Study and comparison of the thermal conductivity of nanofluids and increase of heat transfer due to the effect of size of nano-flow and nano-structure

    Directory of Open Access Journals (Sweden)

    Mohsen Taheri Ghazvini

    2017-01-01

    Full Text Available In this study, the thermal conductivity of nanofluids regarding the effect of size of nano-flow and nano-structure via artificial neural network has been examined. The variations of copper oxide which differ in terms of surface properties, shape and size have been used as nanoparticles in volumetric fraction of 0.001, 0.008 and 0.015. The use of these nanofluids in a heat exchanger tube that should cool a hot solution to a certain size is studied. Results from this research indicate that increase in volumetric fraction and nanofluid temperature causes increase in thermal conductivity of nanofluids which effect of temperature in higher volumetric fractions manifests more.

  19. Structural characterization and electronic structure of laser treated TiN thin film

    Science.gov (United States)

    Soni, Sheetal; Nair, K. G. M.; Phase, D. M.; Gupta, Ratnesh

    2012-06-01

    TiN thin films prepared by laser treatment using Kr-F excimer laser in the controlled atmosphere. The depth distribution and composition of nitrogen and contaminated oxygen have been determined by non-Rutherford proton backscattering using 1.7 MeV Tendetron accelerator. The electronic structure of TiN thin film have been characterized by resonant photoelectron spectroscopy using indus-I synchrotron radiation. Specifically, complex resonance profile that shows the enhancement at 45 eV which is consistent with the resonant photoemission of Ti 3d states involved in the Titanium nitride and oxide.

  20. Synthesis and micro structural investigations of titania-silica nano composite aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Ingale, S.V., E-mail: svingale@barc.gov.in [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sastry, P.U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Wagh, P.B. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tripathi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Rao, R. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tewari, R. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Rao, P.T. [Powder Metallurgy Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Patel, R.P. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2012-08-15

    We have synthesized titania-silica (TiO{sub 2}-SiO{sub 2}) aerogel composites with 20 wt%, 50 wt% and 65 wt% TiO{sub 2} by sol-gel method and investigated their microstructure in detailed using variety of techniques. X-ray diffraction showed formation of the anatase phase of TiO{sub 2} in nano-crystalline form which was confirmed by the broadening of Raman spectra. FTIR studies indicated that TiO{sub 2} is structurally incorporated in to the lattice of silica with formation of the Si-O-Ti linkage. Small angle X-ray scattering study indicated the presence of larger aggregates with rough surfaces. A systematic variation in the morphology of the larger grains and constituting smaller particles (of typical size about 20 nm) with increase in TiO{sub 2} content has been noticed. Pictures from TEM indicated that TiO{sub 2} is confined to the pores in the host silica gel, resulting in formation of TiO{sub 2} nano-crystallites leading to high surface area. Nitrogen-physisorption studies further confirmed that the TiO{sub 2} particles occupy the pores of gel matrix resulting in reduction in the average pore diameter with increasing TiO{sub 2} content. The results from all the techniques clearly suggested that the variations in the microstructure of the composites as prepared by sol-gel method will have significant impact on the optical and catalytic performance of the TiO{sub 2}. -- Highlights: Black-Right-Pointing-Pointer Synthesized successfully TiO{sub 2}-SiO{sub 2} composite aerogels containing up to 65 wt% TiO{sub 2}. Black-Right-Pointing-Pointer Detailed micro structural study to investigate effects of increasing TiO{sub 2} content. Black-Right-Pointing-Pointer Correlated optical and