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Sample records for assembling semiconductor nanocomposites

  1. Assembling semiconductor nanocomposites using DNA replication technologies.

    Energy Technology Data Exchange (ETDEWEB)

    Heimer, Brandon W.; Crown, Kevin K.; Bachand, George David

    2005-11-01

    Deoxyribonucleic acid (DNA) molecules represent Nature's genetic database, encoding the information necessary for all cellular processes. From a materials engineering perspective, DNA represents a nanoscale scaffold with highly refined structure, stability across a wide range of environmental conditions, and the ability to interact with a range of biomolecules. The ability to mass-manufacture functionalized DNA strands with Angstrom-level resolution through DNA replication technology, however, has not been explored. The long-term goal of the work presented in this report is focused on exploiting DNA and in vitro DNA replication processes to mass-manufacture nanocomposite materials. The specific objectives of this project were to: (1) develop methods for replicating DNA strands that incorporate nucleotides with ''chemical handles'', and (2) demonstrate attachment of nanocrystal quantum dots (nQDs) to functionalized DNA strands. Polymerase chain reaction (PCR) and primer extension methodologies were used to successfully synthesize amine-, thiol-, and biotin-functionalized DNA molecules. Significant variability in the efficiency of modified nucleotide incorporation was observed, and attributed to the intrinsic properties of the modified nucleotides. Noncovalent attachment of streptavidin-coated nQDs to biotin-modified DNA synthesized using the primer extension method was observed by epifluorescence microscopy. Data regarding covalent attachment of nQDs to amine- and thiol-functionalized DNA was generally inconclusive; alternative characterization tools are necessary to fully evaluate these attachment methods. Full realization of this technology may facilitate new approaches to manufacturing materials at the nanoscale. In addition, composite nQD-DNA materials may serve as novel recognition elements in sensor devices, or be used as diagnostic tools for forensic analyses. This report summarizes the results obtained over the course of this 1-year

  2. Recent progress on metal core@semiconductor shell nanocomposites as a promising type of photocatalyst

    Science.gov (United States)

    Zhang, Nan; Liu, Siqi; Xu, Yi-Jun

    2012-03-01

    The creation of core-shell nanocomposites (CSNs) has attracted considerable attention and developed into an increasingly important research area at the frontier of advanced materials chemistry. CSNs, which are nanoscaled assemblies with a chemical composition that is different on the surface compared to the core region, have found versatile applications in many fields, such as electrooptics, quantum dots, microscopy labels, drug delivery, chemical sensors, nanoreactors and catalysis. This review is primarily focused on the applications of metal core@semiconductor shell nanocomposites in heterogeneous photocatalysis, including photocatalytic nonselective processes for environmental remediation, selective organic transformations to fine chemicals and water splitting to clean hydrogen energy. It is hoped that this minireview can inspire multidisciplinary research interest in the precisely morphology-controlled synthesis of a variety of metal core@semiconductor shell nanoassemblies and their wide applications in the realm of heterogeneous photocatalysis.

  3. Self-assembled polymer nanocomposites and their networks

    Science.gov (United States)

    Patil, Nitin Vikas

    This dissertation describes new routes to synthesize polymer nanocomposite networks via self-assembly. Polymerizable structure directing agents (referred to as surfmers) obtained by end-group functionalization preserves the structure-directing capabilities of the surfactant for templating ordered mesoporous silica particle growth, while simultaneously generating a reactive matrix for polymer network formation through reactive end groups in the presence of intimately mixed mesoporous silicates. A combination of small angle X-ray scattering, surface area, and microscopy experiments on mesoporous silica indicated the structure directing capabilities of surfmers. Free-radical polymerization of the surfmer leads to novel crosslinked nanocomposites networks. Multiple experiments, including gel permeation chromatography, swelling, and solid state NMR experiments on polymer nanocomposites gave evidence of the polymerization of surfmer leading to formation of crosslink networks. Polymer nanocomposites with varied silica content were prepared. Effects of silica content on polymer nanocomposites were studied on rheometer. Results obtained from rheological experiments indicate that the storage (G') and loss modulus (G") increases with increase in the content of mesoporous silica. In this way, the nanocomposites networks obtained via self-assembly shows independent behavior with respect to frequency in rheological experiments. Additionally, this self-assembled route was extended to synthesize biodegradable and biocompatible polymer nanocomposites networks. The nanocomposite networks obtained with 15% of silica content showed the increase in storage modulus by two orders of magnitude in rheological experiments.

  4. Nanocomposite Membrane via Magnetite Nanoparticle Assembly

    KAUST Repository

    Xie, Yihui

    2012-07-01

    Membrane technology is one of the most promising technologies for addressing the global water crisis as well as in many other applications. One of the drawbacks of current ultra- and nanofiltration membranes is the relatively broad pore size distribution. Block copolymer membranes with ultrahigh permeability and very regular pore sizes have been recently demonstrated with pores being formed by the supramolecular assembly of core/shell micelles. Our study aimed at developing an innovative and economically efficient alternative method to fabricate isoporous membrane by self-assembly of magnetic nanoparticle with a polystyrene shell, mimicking the behavior of block copolymer micelle. Fe3O4 nanoparticles of ~13 nm diameter were prepared by co-precipitation as cores. The initiator for ATRP was covalently bonded onto the surface of magnetic nanoparticles with two strategies. Then the surface initiated ATRP of styrene was carried out to functionalize nanoparticles with polystyrene through a “grafting from” method. Finally, the nanocomposite membrane was cast from 50 wt % Fe3O4@PS brush polymer solution in DMF via non solvent phase inversion. Microscopies reveal an asymmetric membrane with a dense thin layer on top of a porous sponge-like layer. This novel class of asymmetric membrane, based on the pure assembly of functionalized nanoparticles was prepared for the first time. The nanoparticles are well distributed however with no preferential order yet in the as-cast film.I would like to thank my committee chair and advisor, Prof. Suzana Nunes, and other committee members, Prof. Klaus-Viktor Peinemann and Prof. Gary Amy, for their guidance and support throughout the course of this research. My appreciation also goes to my colleagues in our group for useful discussions and suggestions. I also want to extend my gratitude to the staff from the KAUST Core Lab for Advanced Nanofabrication, Imaging and Characterization, especially Dr. Ali Reza Behzad, Dr. Rachid Sougrat, and

  5. Chalcopyrite semimagnetic semiconductors: From nanocomposite to homogeneous material

    Directory of Open Access Journals (Sweden)

    Kilanski L.

    2014-01-01

    Full Text Available Currently, complex ferromagnetic semiconductor systems are of significant interest due to their potential applicability in spintronics. A key feature in order to use semiconductor materials in spintronics is the presence of room temperature ferromagnetism. This feature was recently observed and is intensively studied in several Mn-alloyed II-IV-V2 group diluted magnetic semiconductor systems. The paper reviews the origin of room temperature ferromagnetism in II-IV-V2 compounds. In view of our recent reports the room temperature ferromagnetism in Mn-alloyed chalcopyrite semiconductors with more than 5 molar % of Mn is due to the presence of MnAs clusters. The solubility of magnetic impurities in bulk II-IV-V2 materials is of the order of a few percent, depending on the alloy composition. High values of the conducting hole - Mn ion exchange constant Jpd have significant value equal to 0.75 eV for Zn0.997Mn0.003GeAs2. The sample quality has significant effect on the magnetotransport of the alloy. The magnetoresistance of the alloy change main physical mechanism from spin-disorder scattering and weak localization for homogeneous samples to cluster-related geometrical effect observed for nanocomposite samples. The magnetoresistance of the II-IV-V2 alloys can be then tuned up to a few hundreds of percent via changes of the chemical composition of the alloy as well as a degree of disorder present in a material. [Projekat Ministarstva nauke Republike Srbije, br. III45003

  6. Methods and devices for fabricating and assembling printable semiconductor elements

    Science.gov (United States)

    Nuzzo, Ralph G.; Rogers, John A.; Menard, Etienne; Lee, Keon Jae; Khang, Dahl-Young; Sun, Yugang; Meitl, Matthew; Zhu, Zhengtao

    2009-11-24

    The invention provides methods and devices for fabricating printable semiconductor elements and assembling printable semiconductor elements onto substrate surfaces. Methods, devices and device components of the present invention are capable of generating a wide range of flexible electronic and optoelectronic devices and arrays of devices on substrates comprising polymeric materials. The present invention also provides stretchable semiconductor structures and stretchable electronic devices capable of good performance in stretched configurations.

  7. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode

    Science.gov (United States)

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk

    2016-01-01

    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range. PMID:27255209

  8. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode

    Science.gov (United States)

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk

    2016-06-01

    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range.

  9. Development of self-assembled bacterial cellulose-starch nanocomposites

    International Nuclear Information System (INIS)

    A bioinspired bottom-up process was developed to produce self-assembled nanocomposites of cellulose synthesized by Acetobacter bacteria and native starch. This process takes advantage of the way some bacteria extrude cellulose nanofibres and of the transport process that occurs during the gelatinization of starch. Potato and corn starch were added into the culture medium and partially gelatinized in order to allow the cellulose nanofibrils to grow in the presence of a starch phase. The bacterial cellulose (BC)-starch gels were hot pressed into sheets that had a BC volume fraction higher than 90%. During this step starch was forced to further penetrate the BC network. The self-assembled BC-starch nanocomposites showed a coherent morphology that was assessed by Atomic Force Microscopy (AFM) and Environmental Scanning Electron Microscopy (ESEM). The nanocomposites structure was studied using X-ray diffraction and ATR-FTIR spectroscopy. The degree of crystallinity of the final nanocomposites was used to estimate the volume fraction of BC. The aim of this paper is to explore a new methodology that could be used to produce nanomaterials by introducing a different phase into a cellulose nanofibre network during its assembly.

  10. Development of self-assembled bacterial cellulose-starch nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Grande, Cristian J. [Faculty of Mechanical Engineering, Catholic University of Peru (PUCP), Lima 32 (Peru); Torres, Fernando G., E-mail: fgtorres@pucp.edu.pe [Faculty of Mechanical Engineering, Catholic University of Peru (PUCP), Lima 32 (Peru); Gomez, Clara M., E-mail: Clara.Gomez@uv.es [Departament de Quimica Fisica and Institut de Ciencia dels Materials, Dr Moliner 50, Universitat de Valencia, E-46100 Burjassot, Valencia (Spain); Troncoso, Omar P. [Faculty of Mechanical Engineering, Catholic University of Peru (PUCP), Lima 32 (Peru); Canet-Ferrer, Josep; Martinez-Pastor, Juan [Unit of Optoelectronic Materials and Devices of the University of Valencia, P.O. Box 22085, 46071 Valencia (Spain)

    2009-05-05

    A bioinspired bottom-up process was developed to produce self-assembled nanocomposites of cellulose synthesized by Acetobacter bacteria and native starch. This process takes advantage of the way some bacteria extrude cellulose nanofibres and of the transport process that occurs during the gelatinization of starch. Potato and corn starch were added into the culture medium and partially gelatinized in order to allow the cellulose nanofibrils to grow in the presence of a starch phase. The bacterial cellulose (BC)-starch gels were hot pressed into sheets that had a BC volume fraction higher than 90%. During this step starch was forced to further penetrate the BC network. The self-assembled BC-starch nanocomposites showed a coherent morphology that was assessed by Atomic Force Microscopy (AFM) and Environmental Scanning Electron Microscopy (ESEM). The nanocomposites structure was studied using X-ray diffraction and ATR-FTIR spectroscopy. The degree of crystallinity of the final nanocomposites was used to estimate the volume fraction of BC. The aim of this paper is to explore a new methodology that could be used to produce nanomaterials by introducing a different phase into a cellulose nanofibre network during its assembly.

  11. Preparation and characterization of semiconductor GNR-CNT nanocomposite and its application in FET

    Science.gov (United States)

    Salimian, Sedighe; Azim Araghi, Mohammad Esmaeil; Golikand, Ahmad Nozad

    2016-04-01

    So far, little is known about the experimental potential of graphene nanoribbon-carbon nanotube (GNR-CNT) heterostructure as a semiconductor nanocomposite. The present work examined the structural features, topography and electronic properties of GNR-CNT nanocomposite by using Raman spectroscopy, transmission electron microscopy, scanning tunneling microscopy and spectroscopy (STS). The homogenous semiconductor GNR-CNT nanocomposites were produced under optimized synthesis conditions. The narrow band gap was exhibited by optimization of the reduction step. The STS of the micro-scale surface of the nanocomposite shows local density of state in selected areas that represent the 0.08 eV band gap of a homogenous nanocomposite. The potential of the semiconductor nanocomposite was considered for application in stacked graphene nanoribbon-field effect transistors (SGNR-FETs). A simple method of device fabrication is proposed based on a semiconductor stacked GNR nanocomposite. The high hole mobility and rectifying effect of the p-n junction of the SGNR nanocomposite on TiO2 are demonstrated. The optimal thickness for the back gate TiO2 dielectric for the tested devices was 40 nm. This thickness decreased leakage current at the p-n junction of the SGNR/TiO2 interface, which is promising heterojunction for optoelectronics. The thickness of gate dielectric and quantum capacitance of the gate was investigated at the low 40 nm thickness by calculating the mobility. In the proposed SGNR-FET, holes dominate electrical transport with a high mobility of about 1030 cm2/V s.

  12. Printable semiconductor structures and related methods of making and assembling

    Science.gov (United States)

    Nuzzo, Ralph G.; Rogers, John A.; Menard, Etienne; Lee, Keon Jae; Khang; , Dahl-Young; Sun, Yugang; Meitl, Matthew; Zhu, Zhengtao; Ko, Heung Cho; Mack, Shawn

    2013-03-12

    The present invention provides a high yield pathway for the fabrication, transfer and assembly of high quality printable semiconductor elements having selected physical dimensions, shapes, compositions and spatial orientations. The compositions and methods of the present invention provide high precision registered transfer and integration of arrays of microsized and/or nanosized semiconductor structures onto substrates, including large area substrates and/or flexible substrates. In addition, the present invention provides methods of making printable semiconductor elements from low cost bulk materials, such as bulk silicon wafers, and smart-materials processing strategies that enable a versatile and commercially attractive printing-based fabrication platform for making a broad range of functional semiconductor devices.

  13. Semiconductor monolayer assemblies with oriented crystal faces

    KAUST Repository

    Ma, Guijun

    2012-01-01

    Fabrication of two-dimensional monolayers of crystalline oxide and oxynitride particles was attempted on glass plate substrates. X-Ray diffraction patterns of the assemblies show only specific crystal facets, indicative of the uniform orientation of the particles on the substrate. The selectivity afforded by this immobilization technique enables the organization of randomly distributed polycrystalline powders in a controlled manner.

  14. Chalcopyrite semimagnetic semiconductors: From nanocomposite to homogeneous material

    OpenAIRE

    Kilanski L.; Dobrowolski W.; Szymczak R.; Dynowska E.; Wójcik M.; Romčević M.; Romčević N.; Fedorchenko I.V.; Marenkin S.F.

    2014-01-01

    Currently, complex ferromagnetic semiconductor systems are of significant interest due to their potential applicability in spintronics. A key feature in order to use semiconductor materials in spintronics is the presence of room temperature ferromagnetism. This feature was recently observed and is intensively studied in several Mn-alloyed II-IV-V2 group diluted magnetic semiconductor systems. The paper reviews the origin of room temperature ferromagnetism i...

  15. Plasmonic-exciton coupling in synthesized metal/semiconductor hybrid nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Gadalla, A.; Hamad, D. A. [Physics Department, Assiut University, Assiut (Egypt); Mohamed, M. B. [National Institute of Laser Enhanced science (NIELS), Cairo University, Cairo (Egypt)

    2015-12-31

    A new method has been developed to grow plasmonic semiconductor nanocomposites of Au/CdSe and Ag/CdSe. Their chemical composition and crystal structure are determined by X-ray diffraction. The collective optical properties of the prepared semiconductor nanohybrid have been measured using spectrophotometer techniques and compared to those of the individual components. The electron transfer processes from CdSe to the gold are faster than that of the silver. Au/CdSe has a strong plasmonic-excitonic coupling, but Ag/CdSe has a weak plasmonic-excitonic coupling.

  16. Fatigue crack propagation in self-assembling nanocomposites

    Science.gov (United States)

    Klingler, Andreas; Wetzel, Bernd

    2016-05-01

    Self-assembling block-copolymers allow the easy manufacturing of nanocomposites due to the thermodynamically driven in situ formation of nanosized phases in thermosetting resins during the curing process. Complex mechanical dispersion processes can be avoided. The current study investigates the effect of a block-copolymer on the fatigue crack propagation resistance of a cycloaliphatic amine cured epoxy resin. It was found that a small amount of MAM triblock-copolymer significantly increases the resistance to fatigue crack propagation of epoxy. Crack growth rate and the Paris law exponent for fatigue-crack growth were considerably reduced from m=15.5 of the neat epoxy to m=8.1 of the nanocomposite. To identify the related reinforcing and fracture mechanisms structural analyses of the fractured surfaces were performed by scanning electron microscope. Characteristic features were identified to be deformation, debonding and fracture of the nano-phases as well as crack pinning. However, the highest resistance against fatigue crack propagation was achieved in a bi-continuous microstructure that consisted of an epoxy-rich phase with embedded submicron sized MAM inclusions, and which was surrounded by a block-copolymer-rich phase that showed rupture and plastic deformation.

  17. Self-assembled guanine ribbons as wide-bandgap semiconductors

    Science.gov (United States)

    di Felice, Rosa; Calzolari, Arrigo; Molinari, Elisa; Garbesi, Anna; Rinaldi, Ross; Maruccio, Giuseppe; Cingolani, Roberto

    2002-03-01

    We present a new class of biomolecular wide-bandgap semiconductors, that spontaneously form by the self-assembling of deoxyguanosine molecules (a modified DNA base) in the solid state. Their deposition onto planar metallic nanocircuits allows the fabrication of hybrid nanodiodes and metal/semiconductor/metal devices. By means of first-principle calculations, we describe the structure and the electronic properties of stacked guanine ribbons. We discuss the formation of extended Bloch orbitals, resulting from the superposition of base-localized states, as a function of H-bonding and π-π coupling. The oveall band-like conduction is affected by a dipole-field that spontaneously arise along the ribb n axis. Our theoretical model explains both the basic transport mechanism and the current-voltage characteristics of the devices.

  18. Functional nanocomposites prepared by self-assembly and polymerization of diacetylene surfactants and silicic acid

    Science.gov (United States)

    Yang, Yi; Lu, Yunfeng; Lu, Mengcheng; Huang, Jinman; Haddad, Raid; Xomeritakis, George; Liu, Nanguo; Malanoski, Anthony P.; Sturmayr, Dietmar; Fan, Hongyou; Sasaki, Darryl Y.; Assink, Roger A.; Shelnutt, John A.; van Swol, Frank; Lopez, Gabriel P.; Burns, Alan R.; Brinker, C. Jeffrey

    2003-01-01

    Conjugated polymer/silica nanocomposites with hexagonal, cubic, or lamellar mesoscopic order were synthesized by self-assembly using polymerizable amphiphilic diacetylene molecules as both structure-directing agents and monomers. The self-assembly procedure is rapid and incorporates the organic monomers uniformly within a highly ordered, inorganic environment. By tailoring the size of the oligo(ethylene glycol) headgroup of the diacetylene-containing surfactant, we varied the resulting self-assembled mesophases of the composite material. The nanostructured inorganic host altered the diacetylene polymerization behavior, and the resulting nanocomposites show unique thermo-, mechano-, and solvatochromic properties. Polymerization of the incorporated surfactants resulted in polydiacetylene (PDA)/silica nanocomposites that were optically transparent and mechanically robust. Molecular modeling and quantum calculations and (13)C spin-lattice relaxation times (T(1)) of the PDA/silica nanocomposites indicated that the surfactant monomers can be uniformly organized into precise spatial arrangements prior to polymerization. Nanoindentation and gas transport experiments showed that these nanocomposite films have increased hardness and reduced permeability as compared to pure PDA. Our work demonstrates polymerizable surfactant/silica self-assembly to be an efficient, general approach to the formation of nanostructured conjugated polymers. The nanostructured inorganic framework serves to protect, stabilize, and orient the polymer, mediate its performance, and provide sufficient mechanical and chemical stability to enable integration of conjugated polymers into devices and microsystems.

  19. Densely Packed Linear Assembles of Carbon Nanotube Bundles in Polysiloxane-Based Nanocomposite Films

    OpenAIRE

    Hong-Baek Cho; Minh Triet Tan Huynh; Tadachika Nakayama; Son Thanh Nguyen; Hisayuki Suematsu; Tsuneo Suzuki; Weihua Jiang; Satoshi Tanaka; Yoshinori Tokoi; Soo Wohn Lee; Tohoru Sekino; Koichi Niihara

    2013-01-01

    Linear assemblies of carbon nanotubes (LACNTs) were fabricated and controlled in polysiloxane-based nanocomposite films and the effects of the LACNTs on the thermal and electrical properties of the films were investigated. CNTs were dispersed by mechanical stirring and sonication in a prepolymer of polysiloxane. Homogeneous suspensions were cast on polyamide spacers and oriented by linear-assembly by applying DC and switching DC electric fields before the mixture became cross-linked. Densely ...

  20. Chemical Functionalization, Self-Assembly, and Applications of Nanomaterials and Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Tifeng [Yanshan University; Yan, Xingbin [Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences; Balan, Lavinia [French National Centre for Scientific Research (CNRS), Institute of Materials Science of Mulhouse (IS2M), France; Stepanov, Andrey [Russian Academy of Sciences (RAS), Kazan Physical-Technical Institute, Russia; Chen, Xinqing [Hong Kong University of Science and Technology, Hong Kong; Hu, Michael Z. [ORNL

    2014-01-01

    This special issue addresses the research studies on chemical functionalization, self-assembly, and applications of nanomaterials and nanocomposites. It contains twentyfour articles including two reviews and twenty-two research articles. It is used to create new functional nanomaterials and nanocomposites with a variety of sizes and morphologies such as Zn/Al layered double hydroxide, tin oxide nanowires, FeOOH-modified anion resin, Au nanoclusters silica composite nanospheres, Ti-doped ZnO sol-composite films, TiO2/ZnO composite, graphene oxide nanocomposites, LiFePO4/C nanocomposites, and chitosan nanoparticles. These nanomaterials and nanocomposites have widespread applications in tissue engineering, antitumor, sensors, photoluminescence, electrochemical, and catalytic properties. In addition, this themed issue includes some research articles about self-assembly systems covering organogels and Langmuir films. Furthermore, B. Blasiak et al. performed a literature survey on the recent advances in production, functionalization, toxicity reduction, and application of nanoparticles in cancer diagnosis, treatment, and treatment monitoring. P. Colson et al. performed a literature survey on the recent advances in nanosphere lithography due to its compatibility with wafer-scale processes as well as its potential to manufacture a wide variety of homogeneous one-, two-, or three-dimensional nanostructures.

  1. Synthesis of Self-Assembled Multifunctional Nanocomposite Catalysts with Highly Stabilized Reactivity and Magnetic Recyclability

    Science.gov (United States)

    Yu, Xu; Cheng, Gong; Zheng, Si-Yang

    2016-05-01

    In this paper, a multifunctional Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite catalyst with highly stabilized reactivity and magnetic recyclability was synthesized by a self-assembled method. The magnetic Fe3O4 nanoparticles were coated with a thin layer of the SiO2 to obtain a negatively charged surface. Then positively charged poly(ethyleneimine) polymer (PEI) was self-assembled onto the Fe3O4@SiO2 by electrostatic interaction. Next, negatively charged glutathione capped gold nanoparticles (GSH-AuNPs) were electrostatically self-assembled onto the Fe3O4@SiO2@PEI. After that, silver was grown on the surface of the nanocomposite due to the reduction of the dopamine in the alkaline solution. An about 5 nm thick layer of polydopamine (PDA) was observed to form the Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was carefully characterized by the SEM, TEM, FT-IR, XRD and so on. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite shows a high saturation magnetization (Ms) of 48.9 emu/g, which allows it to be attracted rapidly to a magnet. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was used to catalyze the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) as a model system. The reaction kinetic constant k was measured to be about 0.56 min‑1 (R2 = 0.974). Furthermore, the as-prepared catalyst can be easily recovered and reused for 8 times, which didn’t show much decrease of the catalytic capability.

  2. Tailoring assembly of reduced graphene oxide nanosheets to control gas barrier properties of natural rubber nanocomposites.

    Science.gov (United States)

    Scherillo, Giuseppe; Lavorgna, Marino; Buonocore, Giovanna G; Zhan, Yanhu H; Xia, Hesheng S; Mensitieri, Giuseppe; Ambrosio, Luigi

    2014-02-26

    Self-assembling of reduced graphene oxide platelets, as a tailored interconnected network within a natural rubber matrix, is proposed as a mean for obtaining nanocomposites with improved gas barrier, as compared to neat natural rubber. Interestingly, this nanocomposite structure results to be much more effective than homogeneous dispersion of graphene platelike particles, even at low graphene loadings. Such behavior is interpreted on the grounds of a theoretical model describing permeability of heterogeneous systems specifically accounting for self-segregated graphene morphology. PMID:24490910

  3. Assembly of PbTe/Pb-based nanocomposite and photoelectric property.

    Science.gov (United States)

    Zong, Zhaocun; Wang, Hongxia; Kong, Lingmin

    2013-04-24

    PbTe/Pb-based nanocomposite was assembled by combining the regular PbTe/Pb nanostructure and the ZnxMn1-xS nanoparticles; the photoelectric property of the nanocomposite was measured in situ. The results showed that the through current of the nanocomposite had an obvious increase compared to that of the individual PbTe/Pb nanomaterial under the same irradiation conditions. The improvement of photoelectric performance would be attributed to the synergistic effect brought by the incident light and exciting light of the ZnxMn1-xS nanoparticles. The result implied that the underlying mechanism could be used to improve the performance of nano-optoelectronic devices and the light-use efficiency of solar devices.

  4. Densely Packed Linear Assembles of Carbon Nanotube Bundles in Polysiloxane-Based Nanocomposite Films

    Directory of Open Access Journals (Sweden)

    Hong-Baek Cho

    2013-01-01

    Full Text Available Linear assemblies of carbon nanotubes (LACNTs were fabricated and controlled in polysiloxane-based nanocomposite films and the effects of the LACNTs on the thermal and electrical properties of the films were investigated. CNTs were dispersed by mechanical stirring and sonication in a prepolymer of polysiloxane. Homogeneous suspensions were cast on polyamide spacers and oriented by linear-assembly by applying DC and switching DC electric fields before the mixture became cross-linked. Densely packed LACNTs that fixed the composite film surfaces were fabricated with various structures and thicknesses that depended on the DC and switching DC conditions. Polymer nanocomposites with different LACNT densities exhibited enhanced thermal and electrical conductivities and high optical transmittances. They are considered promising structural materials for electronic sectors in automotive and aerospace applications.

  5. A study into the role of surface capping on energy transfer in metal cluster-semiconductor nanocomposites

    Science.gov (United States)

    Bain, Dipankar; Paramanik, Bipattaran; Sadhu, Suparna; Patra, Amitava

    2015-12-01

    Metal cluster-semiconductor nanocomposite materials remain a frontier area of research for the development of optoelectronic, photovoltaic and light harvesting devices because metal nanoclusters and semiconductor QDs are promising candidates for photon harvesting. Here, we have designed well defined metal cluster-semiconductor nanostructures using different surface capped negatively charged Au25 nanoclusters (Au NCs) and positively charged cysteamine capped CdTe quantum dots using electrostatic interactions. The main focus of this article is to address the impact of surface capping agents on the photophysical properties of Au cluster-CdTe QD hybrid nanocomposites. Steady state and time resolved spectroscopic studies reveal that photoluminescence quenching, radiative and nonradiative rate, and energy transfer between Au nanoclusters and CdTe QDs have been influenced by the nature of the capping agent. We have calculated the energy transfer related parameters such as the overlap integral, distance between donor and acceptor, Förster distance, efficiency of energy transfer and rate of energy transfer from CdTe QDs to three different Au NCs. Photoluminescence quenching varies from 73% to 43% when changing the capping agents from bovine serum albumin (BSA) to glutathione (GSH). The efficiency of the energy transfer from CdTe QDs to BSA-capped Au NCs is found to be 83%, for Cys-capped Au NCs it was 46% and for GSH-capped Au NCs it was 35%. The efficiency depends on the number of Au clusters attached per QD. This reveals that the nature of capping ligands plays a crucial role in the energy transfer phenomena from CdTe QDs to Au NCs. Interesting findings reveal that the efficient energy transfer in metal cluster-semiconductor nanocomposites may open up new possibilities in designing artificial light harvesting systems for future applications.Metal cluster-semiconductor nanocomposite materials remain a frontier area of research for the development of optoelectronic

  6. Synthesis of Self-Assembled Multifunctional Nanocomposite Catalysts with Highly Stabilized Reactivity and Magnetic Recyclability

    OpenAIRE

    Xu Yu; Gong Cheng; Si-Yang Zheng

    2016-01-01

    In this paper, a multifunctional Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite catalyst with highly stabilized reactivity and magnetic recyclability was synthesized by a self-assembled method. The magnetic Fe3O4 nanoparticles were coated with a thin layer of the SiO2 to obtain a negatively charged surface. Then positively charged poly(ethyleneimine) polymer (PEI) was self-assembled onto the Fe3O4@SiO2 by electrostatic interaction. Next, negatively charged glutathione capped gold nanoparticles (GSH-A...

  7. Bottom-up assembly of hydrophobic nanocrystals and graphene nanosheets into mesoporous nanocomposites.

    Science.gov (United States)

    Huang, Jijiang; Liu, Wenxian; Wang, Li; Sun, Xiaoming; Huo, Fengwei; Liu, Junfeng

    2014-04-22

    A general strategy for constructing graphene-based nanocomposites is achieved by emulsion-based bottom-up self-assembly of hydrophobic nanocrystals (NCs) to positively charged colloidal spheres, followed by the electrostatic assembly of NC colloidal spheres with negatively charged graphene oxide in an acidulous aqueous solution. With a simple heat treatment, 3D mesoporous NC spheres/graphene composites are obtained. TiO2/graphene composites typically exhibit a better rate capability and cycle performance than do the corresponding isolated TiO2 spheres. PMID:24684553

  8. Multilayer Thin Films Sequential Assembly of Nanocomposite Materials

    CERN Document Server

    Decher, Gero

    2012-01-01

    This second, comprehensive edition of the pioneering book in this field has been completely revised and extended, now stretching to two volumes. The result is a comprehensive summary of layer-by-layer assembled, truly hybrid nanomaterials and thin films, covering organic, inorganic, colloidal, macromolecular and biological components, plus the assembly of nanoscale films derived from them on surfaces. Praise for the first edition: "... highly recommended to anyone interested in the field... and to scientists and researchers active in materials development..." –Polymer News With contri

  9. Hybrid plasmonic/semiconductor nanoparticle monolayer assemblies as hyperbolic metamaterials

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Ozel, Tuncay; Mutlugun, Evren;

    2014-01-01

    We show that hybrid nanostructures made of alternating colloidal semiconductor quantum dot and metal nanoparticle monolayers can function as multilayer hyperbolic meta-materials. By choosing the thickness of the spacer between the quantum dot and nanoparticle layers, one can achieve the indefinite...... effective permittivity tensor of the structure. This results in increased photonic density of states and strong enhancement of quantum dot luminescence, in line with recent experimental results. Our findings demonstrate that hyperbolic metamaterials can increase the radiative decay rate of emission centers...

  10. Self-Assembled, Iridescent, Crustacean-Mimetic Nanocomposites with Tailored Periodicity and Layered Cuticular Structure.

    Science.gov (United States)

    Wang, Baochun; Walther, Andreas

    2015-11-24

    Natural high-performance materials inspire the pursuit of ordered hard/soft nanocomposite structures at high fractions of reinforcements and with balanced molecular interactions. Herein, we develop a facile, waterborne self-assembly pathway to mimic the multiscale cuticle structure of the crustacean armor by combining hard reinforcing cellulose nanocrystals (CNCs) with soft poly(vinyl alcohol) (PVA). We show iridescent CNC nanocomposites with cholesteric liquid-crystal structure, in which different helical pitches and photonic band gaps can be realized by varying the CNC/PVA ratio. We further show that multilayered crustacean-mimetic materials with tailored periodicity and layered cuticular structure can be obtained by sequential preparation pathways. The transition from a cholesteric to a disordered structure occurs for a critical polymer concentration. Correspondingly, we find a transition from stiff and strong mechanical behavior to materials with increasing ductility. Crack propagation studies using scanning electron microscopy visualize the different crack growth and toughening mechanisms inside cholesteric nanocomposites as a function of the interstitial polymer content for the first time. Different extents of crack deflection, layered delamination, ligament bridging, and constrained microcracking can be observed. Drawing of highly plasticized films sheds light on the mechanistic details of the transition from a cholesteric/chiral nematic to a nematic structure. The study demonstrates how self-assembly of biobased CNCs in combination with suitable polymers can be used to replicate a hierarchical biological structure and how future design of these ordered multifunctional nanocomposites can be optimized by understanding mechanistic details of deformation and fracture. PMID:26372330

  11. Multilayer Thin Films Sequential Assembly of Nanocomposite Materials

    CERN Document Server

    Decher, Gero

    2003-01-01

    Materials scientists are often faced with the problem of modifying surfaces of objects, yet keeping their shape and properties. This book provides a detailed survey on the new technology of adsorption from solution for the fabrication of molecularly ordered multicomposite films in order to replace and expand on the well known Langmuir-Blodgett technology and to open the field of molecular self-assembly to materials and biosciences. The book is aimed at scientists who want to integrate several different functional entities in a single device. To this audience it presents the technique of layer-

  12. Self-assembly of doped semiconductor nanocrystals leading to the formation of highly luminescent nanorods

    International Nuclear Information System (INIS)

    Meso-scale self-assembly of doped semiconductor nanocrystals leading to the formation of monocrystalline nanorods showing enhanced photo- and electro-luminescence properties are reported. Polycrystalline ZnS: Cu+-Al3+ nanoparticles of zinc-blended (cubic) structure with an average size of ∼4 nm were aggregated in aqueous solution and grown into nanorods of length ∼400 nm and aspect ratio ∼12. Transmission electron microscope (TEM) images indicate crystal growth mechanisms involving particle-to-particle oriented-attachment assisted by sulphur-sulphur catenation leading to covalent-linkage. The nanorods exhibit self-assembly dependant luminescence properties such as quenching of the lattice defect-related emissions accompanied by enhancement of dopant-related emission, efficient low-voltage electroluminescence (EL) and super-linear voltage-brightness EL characteristics. This study demonstrates the technological importance of aggregation based self-assembly in doped semiconductor nanosystems

  13. Self-assembly of doped semiconductor nanocrystals leading to the formation of highly luminescent nanorods

    Science.gov (United States)

    Manzoor, K.; Aditya, V.; Vadera, S. R.; Kumar, N.; Kutty, T. R. N.

    2006-03-01

    Meso-scale self-assembly of doped semiconductor nanocrystals leading to the formation of monocrystalline nanorods showing enhanced photo- and electro-luminescence properties are reported. Polycrystalline ZnS: Cu +-Al 3+ nanoparticles of zinc-blended (cubic) structure with an average size of ˜4 nm were aggregated in aqueous solution and grown into nanorods of length ˜400 nm and aspect ratio ˜12. Transmission electron microscope (TEM) images indicate crystal growth mechanisms involving particle-to-particle oriented-attachment assisted by sulphur-sulphur catenation leading to covalent-linkage. The nanorods exhibit self-assembly dependant luminescence properties such as quenching of the lattice defect-related emissions accompanied by enhancement of dopant-related emission, efficient low-voltage electroluminescence (EL) and super-linear voltage-brightness EL characteristics. This study demonstrates the technological importance of aggregation based self-assembly in doped semiconductor nanosystems.

  14. Bio-inspired nanocomposite assemblies as smart skin components.

    Energy Technology Data Exchange (ETDEWEB)

    Montano, Gabriel A.; Xiao, Xiaoyin; Achyuthan, Komandoor E.; Allen, Amy; Brozik, Susan Marie; Edwards, Thayne L.; Frischknecht, Amalie Lucile; Wheeler, David Roger

    2011-09-01

    There is national interest in the development of sophisticated materials that can automatically detect and respond to chemical and biological threats without the need for human intervention. In living systems, cell membranes perform such functions on a routine basis, detecting threats, communicating with the cell, and triggering automatic responses such as the opening and closing of ion channels. The purpose of this project was to learn how to replicate simple threat detection and response functions within artificial membrane systems. The original goals toward developing 'smart skin' assemblies included: (1) synthesizing functionalized nanoparticles to produce electrochemically responsive systems within a lipid bilayer host matrices, (2) calculating the energetics of nanoparticle-lipid interactions and pore formation, and (3) determining the mechanism of insertion of nanoparticles in lipid bilayers via imaging and electrochemistry. There are a few reports of the use of programmable materials to open and close pores in rigid hosts such as mesoporous materials using either heat or light activation. However, none of these materials can regulate themselves in response to the detection of threats. The strategies we investigated in this project involve learning how to use programmable nanomaterials to automatically eliminate open channels within a lipid bilayer host when 'threats' are detected. We generated and characterized functionalized nanoparticles that can be used to create synthetic pores through the membrane and investigated methods of eliminating the pores either through electrochemistry, change in pH, etc. We also focused on characterizing the behavior of functionalized gold NPs in different lipid membranes and lipid vesicles and coupled these results to modeling efforts designed to gain an understanding of the interaction of nanoparticles within lipid assemblies.

  15. Surface Tension Directed Fluidic Self-Assembly of Semiconductor Chips across Length Scales and Material Boundaries

    Directory of Open Access Journals (Sweden)

    Shantonu Biswas

    2016-03-01

    Full Text Available This publication provides an overview and discusses some challenges of surface tension directed fluidic self-assembly of semiconductor chips which are transported in a liquid medium. The discussion is limited to surface tension directed self-assembly where the capture, alignment, and electrical connection process is driven by the surface free energy of molten solder bumps where the authors have made a contribution. The general context is to develop a massively parallel and scalable assembly process to overcome some of the limitations of current robotic pick and place and serial wire bonding concepts. The following parts will be discussed: (2 Single-step assembly of LED arrays containing a repetition of a single component type; (3 Multi-step assembly of more than one component type adding a sequence and geometrical shape confinement to the basic concept to build more complex structures; demonstrators contain (3.1 self-packaging surface mount devices, and (3.2 multi-chip assemblies with unique angular orientation. Subsequently, measures are discussed (4 to enable the assembly of microscopic chips (10 μm–1 mm; a different transport method is introduced; demonstrators include the assembly of photovoltaic modules containing microscopic silicon tiles. Finally, (5 the extension to enable large area assembly is presented; a first reel-to-reel assembly machine is realized; the machine is applied to the field of solid state lighting and the emerging field of stretchable electronics which requires the assembly and electrical connection of semiconductor devices over exceedingly large area substrates.

  16. Peptide linkers for the assembly of semiconductor quantum dot bioconjugates

    Science.gov (United States)

    Boeneman, Kelly; Mei, Bing C.; Deschamps, Jeffrey R.; Delehanty, James B.; Mattoussi, Hedi; Medintz, Igor

    2009-02-01

    The use of semiconductor luminescent quantum dots for the labeling of biomolecules is rapidly expanding, however it still requires facile methods to attach functional globular proteins to biologically optimized quantum dots. Here we discuss the development of controlled variable length peptidyl linkers to attach biomolecules to poly(ethylene) glycol (PEG) coated quantum dots for both in vitro and in vivo applications. The peptides chosen, β-sheets and alpha helices are appended to polyhistidine sequences and this allows for control of the ratio of peptide bioconjugated to QD and the distance from QD to the biomolecule. Recombinant DNA engineering, bacterial peptide expression and Ni-NTA purification of histidine labeled peptides are utilized to create the linkers. Peptide length is confirmed by in vitro fluorescent resonance energy transfer (FRET).

  17. Self-Assembly of Ferritin Nanoparticles into an Enzyme Nanocomposite with Tunable Size for Ultrasensitive Immunoassay.

    Science.gov (United States)

    Men, Dong; Zhang, Ting-Ting; Hou, Li-Wei; Zhou, Juan; Zhang, Zhi-Ping; Shi, Yuan-Yuan; Zhang, Jin-Li; Cui, Zong-Qiang; Deng, Jiao-Yu; Wang, Dian-Bing; Zhang, Xian-En

    2015-11-24

    The self-assembly of nanoparticles into larger superstructures is a powerful strategy to develop novel functional nanomaterials, as these superstructures display collective properties that are different to those displayed by individual nanoparticles or bulk samples. However, there are increasing bottlenecks in terms of size control and multifunctionalization of nanoparticle assemblies. In this study, we developed a self-assembly strategy for construction of multifunctional nanoparticle assemblies of tunable size, through rational regulation of the number of self-assembling interaction sites on each nanoparticle. As proof-of-principle, a size-controlled enzyme nanocomposite (ENC) was constructed by self-assembly of streptavidin-labeled horseradish peroxidase (SA-HRP) and autobiotinylated ferritin nanoparticles (bFNP). Our ENC integrates a large number of enzyme molecules, together with a streptavidin-coated surface, allowing for a drastic increase in enzymatic signal when the SA is bound to a biotinylated target molecule. As result, a 10 000-fold increase in sensitivity over conventional enzyme-linked immunosorbent assays (ELISA) methods was achieved in a cardiac troponin immunoassay. Our method presented here should provide a feasible approach for constructing elaborate multifunctional superstructures of tunable size useful for a broad range of biomedical applications.

  18. Thermoelectric Properties of Self Assembled TiO2/SnO2 Nanocomposites

    Science.gov (United States)

    Dynys, Fred; Sayir, Ali; Sehirlioglu, Alp

    2008-01-01

    Recent advances in improving efficiency of thermoelectric materials are linked to nanotechnology. Thermodynamically driven spinodal decomposition was utilized to synthesize bulk nanocomposites. TiO2/SnO2 system exhibits a large spinodal region, ranging from 15 to 85 mole % TiO2. The phase separated microstructures are stable up to 1400 C. Semiconducting TiO2/SnO2 powders were synthesized by solid state reaction between TiO2 and SnO2. High density samples were fabricated by pressureless sintering. Self assemble nanocomposites were achieved by annealing at 1000 to 1350 C. X-ray diffraction reveal phase separation of (Ti(x)Sn(1-x))O2 type phases. The TiO2/SnO2 nanocomposites exhibit n-type behavior; a power factor of 70 W/mK2 at 1000 C has been achieved with penta-valent doping. Seebeck, thermal conductivity, electrical resistivity and microstructure will be discussed in relation to composition and doping.

  19. Thermoelectric Properties of Self Assemble TiO2/SnO2 Nanocomposites

    Science.gov (United States)

    Dynys, Fred; Sayir, Ali; Sehirlioglu, Alp

    2008-01-01

    Recent advances in improving efficiency of thermoelectric materials are linked to nanotechnology. Thermodynamically driven spinodal decomposition was utilized to synthesize bulk nanocomposites. TiO2/SnO2 system exhibits a large spinodal region, ranging from 15 to 85 mole % TiO2. The phase separated microstructures are stable up to 1400 C. Semiconducting TiO2/SnO2 powders were synthesized by solid state reaction between TiO2 and SnO2. High density samples were fabricated by pressureless sintering. Self assemble nanocomposites were achieved by annealing at 1000 to 1350 C. X-ray diffraction reveal phase separation of (Ti(x)Sn(1-x))O2 type phases. The TiO2/SnO2 nanocomposites exhibit n-type behavior; a power factor of 70 (mu)W/m sq K at 1000 C has been achieved with penta-valent doping. Seebeck, thermal conductivity, electrical resistivity and microstructure will be discussed in relation to composition and doping.

  20. Supramolecular Engineering of Hierarchically Self-Assembled, Bioinspired, Cholesteric Nanocomposites Formed by Cellulose Nanocrystals and Polymers.

    Science.gov (United States)

    Zhu, Baolei; Merindol, Remi; Benitez, Alejandro J; Wang, Baochun; Walther, Andreas

    2016-05-01

    Natural composites are hierarchically structured by combination of ordered colloidal and molecular length scales. They inspire future, biomimetic, and lightweight nanocomposites, in which extraordinary mechanical properties are in reach by understanding and mastering hierarchical structure formation as tools to engineer multiscale deformation mechanisms. Here we describe a hierarchically self-assembled, cholesteric nanocomposite with well-defined colloid-based helical structure and supramolecular hydrogen bonds engineered on the molecular level in the polymer matrix. We use reversible addition-fragmentation transfer polymerization to synthesize well-defined hydrophilic, nonionic polymers with a varying functionalization density of 4-fold hydrogen-bonding ureidopyrimidinone (UPy) motifs. We show that these copolymers can be coassembled with cellulose nanocrystals (CNC), a sustainable, stiff, rod-like reinforcement, to give ordered cholesteric phases with characteristic photonic stop bands. The dimensions of the helical pitch are controlled by the ratio of polymer/CNC, confirming a smooth integration into the colloidal structure. With respect to the effect of the supramolecular motifs, we demonstrate that those regulate the swelling when exposing the biomimetic hybrids to water, and they allow engineering the photonic response. Moreover, the amount of hydrogen bonds and the polymer fraction are decisive in defining the mechanical properties. An Ashby plot comparing previous ordered CNC-based nanocomposites with our new hierarchical ones reveals that molecular engineering allows us to span an unprecedented mechanical property range from highest inelastic deformation (strain up to ∼13%) to highest stiffness (E ∼ 15 GPa) and combinations of both. We envisage that further rational design of the molecular interactions will provide efficient tools for enhancing the multifunctional property profiles of such bioinspired nanocomposites. PMID:27067311

  1. Self-Assembled Epitaxial Au-Oxide Vertically Aligned Nanocomposites for Nanoscale Metamaterials.

    Science.gov (United States)

    Li, Leigang; Sun, Liuyang; Gomez-Diaz, Juan Sebastian; Hogan, Nicki L; Lu, Ping; Khatkhatay, Fauzia; Zhang, Wenrui; Jian, Jie; Huang, Jijie; Su, Qing; Fan, Meng; Jacob, Clement; Li, Jin; Zhang, Xinghang; Jia, Quanxi; Sheldon, Matthew; Alù, Andrea; Li, Xiaoqin; Wang, Haiyan

    2016-06-01

    Metamaterials made of nanoscale inclusions or artificial unit cells exhibit exotic optical properties that do not exist in natural materials. Promising applications, such as super-resolution imaging, cloaking, hyperbolic propagation, and ultrafast phase velocities have been demonstrated based on mostly micrometer-scale metamaterials and few nanoscale metamaterials. To date, most metamaterials are created using costly and tedious fabrication techniques with limited paths toward reliable large-scale fabrication. In this work, we demonstrate the one-step direct growth of self-assembled epitaxial metal-oxide nanocomposites as a drastically different approach to fabricating large-area nanostructured metamaterials. Using pulsed laser deposition, we fabricated nanocomposite films with vertically aligned gold (Au) nanopillars (∼20 nm in diameter) embedded in various oxide matrices with high epitaxial quality. Strong, broad absorption features in the measured absorbance spectrum are clear signatures of plasmon resonances of Au nanopillars. By tuning their densities on selected substrates, anisotropic optical properties are demonstrated via angular dependent and polarization resolved reflectivity measurements and reproduced by full-wave simulations and effective medium theory. Our model predicts exotic properties, such as zero permittivity responses and topological transitions. Our studies suggest that these self-assembled metal-oxide nanostructures provide an exciting new material platform to control and enhance optical response at nanometer scales.

  2. Biomimetic Nanocomposites of Calcium Phosphate and Self-Assembling Triblock and Pentablock Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Drew Lenzen Enlow

    2006-08-09

    In an effort to mimic the growth of natural bone, self-assembling, micelle and gel-forming copolymers were used as a template for calcium phosphate precipitation. Because of the cationic characteristics imparted by PDEAEM end group additions to commercially available Pluronic{reg_sign} Fl27, a direct ionic attraction mechanism was utilized and a polymer-brushite nanocomposite spheres were produced. Brushite coated spherical micelles with diameters of {approx}40 nm, and agglomerates of these particles (on the order of 0.5 {mu}m) were obtained. Thickness and durability of the calcium phosphate coating, and the extent of agglomeration were studied. The coating has been shown to be robust enough to retain its integrity even below polymer critical micelle concentration and/or temperature. Calcium phosphate-polymer gel nanocomposites were also prepared. Gel samples appeared as a single phase network of agglomerated spherical micelles, and had a final calcium phosphate concentration of up to 15 wt%. Analysis with x-ray diffraction and NMR indicated a disordered brushite phase with the phosphate groups linking inorganic phase to the polymer.

  3. Biomimetic Nanocomposites of Calcium Phosphate and Self-Assembling Triblock and Pentablock Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Enlow, Drew Lenzen [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    In an effort to mimic the growth of natural bone, self-assembling, micelle and gel-forming copolymers were used as a template for calcium phosphate precipitation. Because of the cationic characteristics imparted by PDEAEM end group additions to commercially available Pluronic{reg_sign} Fl27, a direct ionic attraction mechanism was utilized and a polymer-brushite nanocomposite spheres were produced. Brushite coated spherical micelles with diameters of ~40 nm, and agglomerates of these particles (on the order of 0.5 μm) were obtained. Thickness and durability of the calcium phosphate coating, and the extent of agglomeration were studied. The coating has been shown to be robust enough to retain its integrity even below polymer critical micelle concentration and/or temperature. Calcium phosphate-polymer gel nanocomposites were also prepared. Gel samples appeared as a single phase network of agglomerated spherical micelles, and had a final calcium phosphate concentration of up to 15 wt%. Analysis with x-ray diffraction and NMR indicated a disordered brushite phase with the phosphate groups linking inorganic phase to the polymer.

  4. Effect of titanium oxide-polystyrene nanocomposite dielectrics on morphology and thin film transistor performance for organic and polymeric semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Della Pelle, Andrea M. [LGS Innovations, 15 Vreeland Rd., Florham Park, NJ 07932 (United States); Department of Chemistry, University of Massachusetts Amherst, 710 N. Pleasant St. Amherst, MA 01003 (United States); Maliakal, Ashok, E-mail: maliakal@lgsinnovations.com [LGS Innovations, 15 Vreeland Rd., Florham Park, NJ 07932 (United States); Sidorenko, Alexander [Department of Chemistry and Biochemistry, University of the Sciences, 600 South 43rd St., Philadelphia, PA 191034 (United States); Thayumanavan, S. [Department of Chemistry, University of Massachusetts Amherst, 710 N. Pleasant St. Amherst, MA 01003 (United States)

    2012-07-31

    Previous studies have shown that organic thin film transistors with pentacene deposited on gate dielectrics composed of a blend of high K titanium oxide-polystyrene core-shell nanocomposite (TiO{sub 2}-PS) with polystyrene (PS) perform with an order of magnitude increase in saturation mobility for TiO{sub 2}-PS (K = 8) as compared to PS devices (K = 2.5). The current study finds that this performance enhancement can be translated to alternative small single crystal organics such as {alpha}-sexithiophene ({alpha}-6T) (enhancement factor for field effect mobility ranging from 30-100 Multiplication-Sign higher on TiO{sub 2}-PS/PS blended dielectrics as compared to homogenous PS dielectrics). Interestingly however, in the case of semicrystalline polymers such as (poly-3-hexylthiophene) P3HT, this dramatic enhancement is not observed, possibly due to the difference in processing conditions used to fabricate these devices (film transfer as opposed to thermal evaporation). The morphology for {alpha}-sexithiophene ({alpha}-6T) grown by thermal evaporation on TiO{sub 2}-PS/PS blended dielectrics parallels that observed in pentacene devices. Smaller grain size is observed for films grown on dielectrics with higher TiO{sub 2}-PS content. In the case of poly(3-hexylthiophene) (P3HT) devices, constructed via film transfer, morphological differences exist for the P3HT on different substrates, as discerned by atomic force microscopy studies. However, these devices only exhibit a modest (2 Multiplication-Sign ) increase in mobility with increasing TiO{sub 2}-PS content in the films. After annealing of the transferred P3HT thin film transistor (TFT) devices, no appreciable enhancement in mobility is observed across the different blended dielectrics. Overall the results support the hypothesis that nucleation rate is responsible for changes in film morphology and device performance in thermally evaporated small molecule crystalline organic semiconductor TFTs. The increased nucleation

  5. Effect of titanium oxide–polystyrene nanocomposite dielectrics on morphology and thin film transistor performance for organic and polymeric semiconductors

    International Nuclear Information System (INIS)

    Previous studies have shown that organic thin film transistors with pentacene deposited on gate dielectrics composed of a blend of high K titanium oxide–polystyrene core–shell nanocomposite (TiO2–PS) with polystyrene (PS) perform with an order of magnitude increase in saturation mobility for TiO2–PS (K = 8) as compared to PS devices (K = 2.5). The current study finds that this performance enhancement can be translated to alternative small single crystal organics such as α-sexithiophene (α-6T) (enhancement factor for field effect mobility ranging from 30-100× higher on TiO2–PS/PS blended dielectrics as compared to homogenous PS dielectrics). Interestingly however, in the case of semicrystalline polymers such as (poly-3-hexylthiophene) P3HT, this dramatic enhancement is not observed, possibly due to the difference in processing conditions used to fabricate these devices (film transfer as opposed to thermal evaporation). The morphology for α-sexithiophene (α-6T) grown by thermal evaporation on TiO2–PS/PS blended dielectrics parallels that observed in pentacene devices. Smaller grain size is observed for films grown on dielectrics with higher TiO2–PS content. In the case of poly(3-hexylthiophene) (P3HT) devices, constructed via film transfer, morphological differences exist for the P3HT on different substrates, as discerned by atomic force microscopy studies. However, these devices only exhibit a modest (2×) increase in mobility with increasing TiO2–PS content in the films. After annealing of the transferred P3HT thin film transistor (TFT) devices, no appreciable enhancement in mobility is observed across the different blended dielectrics. Overall the results support the hypothesis that nucleation rate is responsible for changes in film morphology and device performance in thermally evaporated small molecule crystalline organic semiconductor TFTs. The increased nucleation rate produces organic polycrystalline films with small grain size which are

  6. High temperature magnetic order in Zn1-x Mn x SnSb2+MnSb nanocomposite ferromagnetic semiconductors.

    Science.gov (United States)

    Kilanski, L; Górska, M; Ślawska-Waniewska, A; Lewińska, S; Szymczak, R; Dynowska, E; Podgórni, A; Dobrowolski, W; Ralević, U; Gajić, R; Romčević, N; Fedorchenko, I V; Marenkin, S F

    2016-08-24

    We present studies of structural, magnetic, and electrical properties of Zn1-x Mn x SnSb2+MnSb nanocomposite ferromagnetic semiconductors with the average Mn-content, [Formula: see text], changing from 0.027 up to 0.138. The magnetic force microscope imaging done at room temperature shows the presence of a strong signal coming from MnSb clusters. Magnetic properties show the paramagnet-ferromagnet transition with the Curie temperature, T C, equal to about 522 K and the cluster-glass behavior with the transition temperature, T CG, equal to about 465 K, both related to MnSb clusters. The magnetotransport studies show that all investigated samples are p-type semiconductors with high hole concentration, p, changing from 10(21) to 10(22) cm(-3). A large increase in the resistivity as a function of the magnetic field is observed at T  <  10 K and small magnetic fields, [Formula: see text] mT, for all the studied samples with a maximum amplitude of the magnetoresistance about 460% at T  =  1.4 K. The large increase in the resistivity is most probably caused by the appearance of the superconducting state in the samples at T  <  4.3 K. PMID:27351672

  7. Crystallization of II-VI semiconductor compounds forming long microcrystalline linear assemblies

    Directory of Open Access Journals (Sweden)

    Marcelino Becerril

    2013-04-01

    Full Text Available In this work we report the formation of long microcrystalline linear self-assemblies observed during the thin film growth of several II-VI compounds. Polycrystalline CdTe, CdS, CdCO3, and nanocrystalline CdTe:Al thin films were prepared on glass substrates by different deposition techniques. In order to observe these crystalline formations in the polycrystalline materials, the thin film growth was suspended before the grains reached to form a continuous layer. The chains of semiconductor crystals were observed among many isolated and randomly distributed grains. Since CdTe, CdTe:Al, CdS and CdCO3 are not ferroelectric and/or ferromagnetic materials, the relevant problem would be to explain what is the mechanism through which the grains are held together to form linear chains. It is well known that some nanocrystalline materials form rods and wires by means of electrostatic forces. This occurs in polar semiconductors, where it is assumed that the attraction forces between surface polar faces of the small crystals are the responsible for the chains formation. Since there are not too many mechanisms responsible for the attraction we assume that a dipolar interaction is the force that originates the formation of chain-like grain clusters. The study of this property can be useful for the understanding of nucleation processes in the growth of semiconductor thin films.

  8. Enhancing Crystalline Structural Orders of Polymer Semiconductors for Efficient Charge Transport via Polymer-Matrix-Mediated Molecular Self-Assembly.

    Science.gov (United States)

    Lei, Yanlian; Deng, Ping; Lin, Ming; Zheng, Xuelin; Zhu, Furong; Ong, Beng S

    2016-08-01

    A facile polymer-matrix-mediated molecular self-assembly of polymer semiconductors into highly crystalline orders for efficient charge transport in organic thin-film transistors is demonstrated. Phenomenal enhancements in field-effect mobility of about one order of magnitude and current on/off ratio of two to three orders of magnitude are realized with polyacrylonitrile-incorporated polymer semiconductor compositions via solution deposition. PMID:27168128

  9. Ion-scattering analysis of self-assembled monolayers of silanes on organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Wielunski, Leszek S., E-mail: leszekw@physics.rutgers.ed [Institute for Advanced Materials and Devices for Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States); Katalinic, S.; Lee, B. [Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States); Connors, M. [Department of Chemistry, Rutgers University, Piscataway, NJ 08854 (United States); Garfunkel, E. [Institute for Advanced Materials and Devices for Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Chemistry, Rutgers University, Piscataway, NJ 08854 (United States); Feldman, L.C.; Podzorov, V. [Institute for Advanced Materials and Devices for Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States)

    2010-06-15

    We describe new Rutherford Backscattering Spectroscopy (RBS) measurements to explore the surface chemistry associated with the growth of self-assembled monolayer (SAM) molecules on conducting organic films. The report includes a description of the optimization of both substrates and RBS scattering parameters to appropriately analyze these novel and damage susceptible structures. Our RBS measurements reveal that the final surface stoichiometry is consistent with a specific model of hydrolyzed and crosslinked trichlorosilanes that form a dense two-dimensional network (a monolayer) at the surface of small-molecule organic semiconductors and a bulk SAM network in the case of conjugated polymer films. Organic semiconductors used in this study are thin films of rubrene (a small molecule semiconductor (C{sub 42}H{sub 28})) and poly(3-hexyl)thiophene (P3HT) (a conjugated polymer (C{sub 10}H{sub 18}S){sub n}). As a substrate we used a thick (1 {mu}m) film of parylene (a non-conjugated polymer (C{sub 8}H{sub 8}){sub n}) deposited on Si (1 0 0) wafers. The SAM molecules used to functionalize the organic semiconductor films are fluoroalkyl trichlorosilane (FTS) (C{sub 8}(H{sub 4}F{sub 13})SiCl{sub 3}) and octyltrichlorosilane (OTS) (C{sub 8}H{sub 17}SiCl{sub 3}). Quantitative detection of medium and small-mass elements, such as O, F, Si, S and residual Cl is demonstrated and used to elucidate the surface chemistry in these novel organic systems.

  10. Smart assembling of multi-scaled functional interfaces in thermoelectric Ga2Te3/Te hetero-nanocomposites

    Science.gov (United States)

    Chang, Hsiu-Cheng; Chiang, Ming-Hsiu; Tsai, Tsung-Che; Chen, Tsung-Han; Whang, Wha-Tzong; Chen, Chun-Hua

    2014-11-01

    We describe an innovative concept and facile approach in fabricating laterally assembled Ga2Te3/Te binary nanocomposite films, which comprise two-dimensional quasi-periodic Ga2Te3 nanoassemblies surrounded by interlocking highly-conductive Te single crystals for comprehensively establishing subnano- to micro-scaled multi-style versatile interfaces. The distinct Ga2Te3/Te nanocomposite film exhibits a power factor that is about 60 times higher than the reported conventional Ga2Te3 and Te materials, mainly due to the 2- to 3-order improved electrical conductivity and the comparable Seebeck coefficient.We describe an innovative concept and facile approach in fabricating laterally assembled Ga2Te3/Te binary nanocomposite films, which comprise two-dimensional quasi-periodic Ga2Te3 nanoassemblies surrounded by interlocking highly-conductive Te single crystals for comprehensively establishing subnano- to micro-scaled multi-style versatile interfaces. The distinct Ga2Te3/Te nanocomposite film exhibits a power factor that is about 60 times higher than the reported conventional Ga2Te3 and Te materials, mainly due to the 2- to 3-order improved electrical conductivity and the comparable Seebeck coefficient. Electronic supplementary information (ESI) available: Structural investigations of the hetero-nanocomposite films formed at an annealing temperature of 225 °C for 12 h, 250 °C for 3 h, and 225 °C for 3 h are collected in Fig. S1-S3, respectively. Annealing temperature and time effects on the morphology, composition, crystallinity and thermoelectric property are shown in Fig. S4-S10. See DOI: 10.1039/c4nr02765e

  11. Nanocomposite

    Science.gov (United States)

    Seifzadeh, Davod; Rahimzadeh Hollagh, Amin

    2014-11-01

    Electroless Ni-Co-P coating and Ni-Co-P-SiO2 nanocomposites were successfully applied on AZ91D magnesium alloy via environmentally friendly cerium-lanthanum-permanganate treatment and their properties were compared with traditionally binary Ni-P coating. The prepared coatings were analyzed using scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray spectroscopy. Moreover, the corrosion behavior of the coatings in 3.5 wt.% NaCl was evaluated by two electrochemical methods. It is found that the Ni-Co-P coating possesses more uniform and compact structure and better corrosion protection characteristics in comparison with the Ni-P coating. The plating rate of Ni-Co-P bath is relatively lower than the Ni-P bath, but it significantly increases after addition of SiO2 nanoparticles more probably due to adsorption of silica nanoparticles on alloy surface. The corrosion resistance of Ni-Co-P-SiO2 composite coatings was superior with respect to Ni-P and Ni-Co-P coatings due to formation of thick and compact coating with tortuous grain boundaries.

  12. Highly Efficient Photothermal Semiconductor Nanocomposites for Photothermal Imaging of Latent Fingerprints.

    Science.gov (United States)

    Cui, Jiabin; Xu, Suying; Guo, Chang; Jiang, Rui; James, Tony D; Wang, Leyu

    2015-11-17

    Optical imaging of latent fingerprints (LFPs) has been widely used in forensic science and for antiterrorist applications, but it suffers from interference from autofluorescence and the substrates background color. Cu7S4 nanoparticles (NPs), with excellent photothermal properties, were synthesized using a new strategy and then fabricated into amphiphilic nanocomposites (NCs) via polymerization of allyl mercaptan coated on Cu7S4 NPs to offer good affinities toward LFPs. Here, we develop a facile and versatile photothermal LFP imaging method based on the high photothermal conversion efficiency (52.92%, 808 nm) of Cu7S4 NCs, indicating its effectiveness for imaging LFPs left on different substrates (with various background colors), which will be extremely useful for crime scene investigations. Furthermore, by fabricating Cu7S4-CdSe@ZnS NCs, a fluorescent-photothermal dual-mode imaging strategy was used to detect trinitrotoluene (TNT) in LFPs while still maintaining a complete photothermal image of LFP.

  13. Self-assembled lamellar MoS2, SnS2 and SiO2 semiconducting polymer nanocomposites.

    Science.gov (United States)

    Kirmayer, Saar; Aharon, Eyal; Dovgolevsky, Ekaterina; Kalina, Michael; Frey, Gitti L

    2007-06-15

    Lamellar nanocomposites based on semiconducting polymers incorporated into layered inorganic matrices are prepared by the co-assembly of organic and inorganic precursors. Semiconducting polymer-incorporated silica is prepared by introducing the semiconducting polymers into a tetrahydrofuran (THF)/water homogeneous sol solution containing silica precursor species and a surface-active agent. Semiconducting polymer-incorporated MoS(2) and SnS(2) are prepared by Li intercalation into the inorganic compound, exfoliation and restack in the presence of the semiconducting polymer. All lamellar nanocomposite films are organized in domains aligned parallel to the substrate surface plane. The incorporated polymers maintain their semiconducting properties, as evident from their optical absorption and photoluminescence spectra. The optoelectronic properties of the nanocomposites depend on the properties of both the inorganic host and the incorporated guest polymer as demonstrated by integrating the nanocomposite films into light-emitting diodes. Devices based on polymer-incorporated silica and polymer-incorporated MoS(2) show no diode behaviour and no light emission due to the insulating and metallic properties of the silica and MoS(2) hosts. In contrast, diode performance and electroluminescence are obtained from devices based on semiconducting polymer-incorporated semiconducting SnS(2), demonstrating that judicious selection of the composite components in combination with the optimization of material synthesis conditions allows new hierarchical structures to be tailored for electronic and optoelectronic applications.

  14. Assembling strategy to synthesize palladium modified kaolin nanocomposites with different morphologies

    Science.gov (United States)

    Li, Xiaoyu; Ouyang, Jing; Zhou, Yonghua; Yang, Huaming

    2015-09-01

    Nanocomposites of aluminosilicate minerals, kaolins (kaolinite and halloysite) with natural different morphologies assembling with palladium (Pd) nanoparticles have been successfully synthesized through strong electrostatic adsorption and chemical bonding after surface modification with 3-aminopropyl triethoxysilane (APTES). Meanwhile, the influence of different morphologies supports on catalytic hydrogenation properties was explored. The surface concentration of amino groups on the kaolins was related to the morphology and surface nature. Electronmicroscopy revealed that the monodisperse Pd nanoparticles were uniformly deposited onto the surface of kaolins, ranging in diameter from 0.5 nm to 5.5 nm. The functional groups could not only improve the dispersion of kaolins with different morphologies in solution, but also enhance the interaction between Pd precursors and kaolins, thus preventing small Pd nanoparticles from agglomerating and leading to high activity for the catalytic hydrogenation of styrene. Pd-FK@APTES was more active compared to other samples. Selecting the kaolin morphology with a different surface nature allows the selective surface modification of a larger fraction of the reactive facets on which the active sites can be enriched and tuned. This desirable surface coordination of catalytically active atoms could substantially improve catalytic activity.

  15. Colloid electrostatic self-assembly synthesis of SnO{sub 2}/graphene nanocomposite for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yankun; Liu, Yushan; Zhang, Jianmin, E-mail: zhjm@zzu.edu.cn [Zhengzhou University, College of Chemistry and Molecular Engineering (China)

    2015-10-15

    In this paper, a simple and fast colloid electrostatic self-assembly method was adopted to prepare the SnO{sub 2}/graphene nanocomposite (SGNC). The crystal structure, chemical composition, and porous property of composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman microscopy, X-ray photoelectron spectroscopy (XPS), and N{sub 2} adsorption–desorption experiments. The morphology analyses showed that the SnO{sub 2} nanoparticles about 5 nm were distributed homogenously on the reduced graphene oxide (rGO) sheets surface. The electrochemical performance measurements exhibited that SGNC possessed the specific capacitance of 347.3 F g{sup −1} at a scan rate of 5 mV s{sup −1} in 1 M Na{sub 2}SO{sub 4} electrolyte solution. Furthermore, this material also showed excellent cycling stability, and the specific capacitance still retained 90 % after 3000 cycles. These results indicate that the SGNC is a promising electrode material for high-performance supercapacitors.

  16. Self-Assembled Nanocomposite Organic Polymers with Aluminum and Scandium as Heterogeneous Water-Compatible Lewis Acid Catalysts.

    Science.gov (United States)

    Miyamura, Hiroyuki; Sonoyama, Arisa; Hayrapetyan, Davit; Kobayashi, Shū

    2015-09-01

    While water-compatible Lewis acids have great potential as accessible and environmentally benign catalysts for various organic transformations, efficient immobilization of such Lewis acids while keeping high activity and without leaching of metals even under aqueous conditions is a challenging task. Self-assembled nanocomposite catalysts of organic polymers, carbon black, aluminum reductants, and scandium salts as heterogeneous water-compatible Lewis acid catalysts are described. These catalysts could be successfully applied to various C-C bond-forming reactions without leaching of metals. Scanning transmission electron microscopy analyses revealed that the nanocomposite structure of Al and Sc was fabricated in these heterogeneous catalysts. It is noted that Al species, which are usually decomposed rapidly in the presence of water, are stabilized under aqueous conditions. PMID:26228075

  17. Preparation and Preliminary Dielectric Characterization of Structured C60-Thiol-Ene Polymer Nanocomposites Assembled Using the Thiol-Ene Click Reaction

    Directory of Open Access Journals (Sweden)

    Hanaa M. Ahmed

    2015-11-01

    Full Text Available Fullerene-containing materials have the ability to store and release electrical energy. Therefore, fullerenes may ultimately find use in high-voltage equipment devices or as super capacitors for high electric energy storage due to this ease of manipulating their excellent dielectric properties and their high volume resistivity. A series of structured fullerene (C60 polymer nanocomposites were assembled using the thiol-ene click reaction, between alkyl thiols and allyl functionalized C60 derivatives. The resulting high-density C60-urethane-thiol-ene (C60-Thiol-Ene networks possessed excellent mechanical properties. These novel networks were characterized using standard techniques, including infrared spectroscopy (FTIR, differential scanning calorimetry (DSC, dynamic mechanical analysis (DMA, and thermal gravimetric analysis (TGA. The dielectric spectra for the prepared samples were determined over a broad frequency range at room temperature using a broadband dielectric spectrometer and a semiconductor characterization system. The changes in thermo-mechanical and electrical properties of these novel fullerene-thiol-ene composite films were measured as a function of the C60 content, and samples characterized by high dielectric permittivity and low dielectric loss were produced. In this process, variations in chemical composition of the networks were correlated to performance characteristics.

  18. Hybrid magnetic – Semiconductor nanocomposites: optical, magnetic and nanosecond dynamical properties

    Energy Technology Data Exchange (ETDEWEB)

    Emam, A.N.; Girgis, E.; Mostafa, A.A. [National Research Center, Dokki, Giza (Egypt); Guirguis, O.W. [Biophysics Department, Faculty of Science, Cairo University, Giza (Egypt); Mohamed, M.B., E-mail: monabmohamed@gmail.com [National Institute of Laser Enhanced Science, Cairo University, Giza (Egypt); NanoTech Egypt for Photoelectronics, Dreamland, Giza (Egypt)

    2015-07-15

    A series of colloidal CdSe quantum dots doped with different concentration of cobalt ions has been prepared via organometallic pyrolysis of a mixture of cadmium stearate and cobalt dithiocarbazate. The conditions required for successful doping depend on the source of cobalt ions and the dopant concentration. The structure and morphology of the prepared nanocrystals have been characterized using X-Ray Diffraction (XRD), and Transmission Electron Microscope (TEM). Slight shift in the interplaner space was observed in the XRD pattern of the doped nanocrystals. Formation of separate cobalt nanoclusters has been observed in the TEM images upon increasing the cobalt concentration more than 2% of the original cadmium concentration. This was confirmed by magnetic measurements of the prepared samples. Room-temperature ferromagnetism has been observed, in which the switching field increases as the cobalt ratio increases. Increasing the cobalt ratio more than 5% increases the coercivity due to formation of Co{sup 0} nanoclusters. Moreover, the presence of localized magnetic ions in semiconductor QDs leads to strong exchange interactions between sp band electrons and the magnetic ions d electrons. This would influence the optical properties such as absorption, emission, as well as nanosecond relaxation dynamics. - Graphical abstract: Display Omitted - Highlights: • Hybrid semiconductor-magnetic nanostructure was prepared via chemical method. • Room-temperature ferromagnetism for hybrid CdSe–Co quantum dots has been observed. • Co{sup +2} ions induces slight shift in the interplaner space distance of the doped QDs. • Hybrid CdSe–Co QDs have better quantum yield than pure CdSe QDs. • Hybrid CdSe–Co nanocrystals have faster electron-hole dynamics than pure CdSe QDs.

  19. Performance of dielectric nanocomposites: matrix-free, hairy nanoparticle assemblies and amorphous polymer-nanoparticle blends.

    Science.gov (United States)

    Grabowski, Christopher A; Koerner, Hilmar; Meth, Jeffrey S; Dang, Alei; Hui, Chin Ming; Matyjaszewski, Krzysztof; Bockstaller, Michael R; Durstock, Michael F; Vaia, Richard A

    2014-12-10

    Demands to increase the stored energy density of electrostatic capacitors have spurred the development of materials with enhanced dielectric breakdown, improved permittivity, and reduced dielectric loss. Polymer nanocomposites (PNCs), consisting of a blend of amorphous polymer and dielectric nanofillers, have been studied intensely to satisfy these goals; however, nanoparticle aggregates, field localization due to dielectric mismatch between particle and matrix, and the poorly understood role of interface compatibilization have challenged progress. To expand the understanding of the inter-relation between these factors and, thus, enable rational optimization of low and high contrast PNC dielectrics, we compare the dielectric performance of matrix-free hairy nanoparticle assemblies (aHNPs) to blended PNCs in the regime of low dielectric contrast to establish how morphology and interface impact energy storage and breakdown across different polymer matrices (polystyrene, PS, and poly(methyl methacrylate), PMMA) and nanoparticle loadings (0-50% (v/v) silica). The findings indicate that the route (aHNP versus blending) to well-dispersed morphology has, at most, a minor impact on breakdown strength trends with nanoparticle volume fraction; the only exception being at intermediate loadings of silica in PMMA (15% (v/v)). Conversely, aHNPs show substantial improvements in reducing dielectric loss and maintaining charge/discharge efficiency. For example, low-frequency dielectric loss (1 Hz-1 kHz) of PS and PMMA aHNP films was essentially unchanged up to a silica content of 50% (v/v), whereas traditional blends showed a monotonically increasing loss with silica loading. Similar benefits are seen via high-field polarization loop measurements where energy storage for ∼15% (v/v) silica loaded PMMA and PS aHNPs were 50% and 200% greater than respective comparable PNC blends. Overall, these findings on low dielectric contrast PNCs clearly point to the performance benefits of

  20. Structural assembly effects of Pt nanoparticle-carbon nanotube-polyaniline nanocomposites on the enhancement of biohydrogen fuel cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Hoa, Le Quynh, E-mail: hoa@p.eng.osaka-u.ac.jp [Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Sugano, Yasuhito; Yoshikawa, Hiroyuki; Saito, Masato [Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Tamiya, Eiichi, E-mail: tamiya@ap.eng.osaka-u.ac.jp [Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2011-11-30

    Graphical abstract: - Abstract: In this work, we designed various polyaniline (PANI) nanocomposites with platinum (Pt) nanoparticle-decorated multi-walled carbon nanotubes (MWCNTs), employed them as anodic catalysts, and studied their structural assembly effects with regard to enhancing biohydrogen fuel cell performance. Of two proposed structures, the PANI/Pt/MWCNTs multilayer nanocomposites showed superior electrocatalytic activities in the hydrogen oxidation reaction and in fuel cell power density relative to the Pt/MWCNTs-PANI core-shell design. These enhancements were attributed to the active interface formed between the Pt nanoparticles and polyaniline nanofibers, where the higher electronic and ionic conductivities of the thin PANI nanofiber layers in contact with Pt active sites were better than with the PANI bound Pt/MWCNTs. We also investigated the change in the electronic state of the composites and the charge-transfer rate caused by varying the structural assembly. Finally, the role of each catalyst component was examined to understand its individual effect on fuel cell performance and to understand its structural assembly effect on enhanced power density.

  1. Multiple constituents co-assembly of ordered mesoporous Al2O3-SiO2-carbon nanocomposites.

    Science.gov (United States)

    Wang, Wei; Xue, Huanhuan; Feng, Cuimiao; Kong, Lina; Zhao, Qingfei; Wan, Ying

    2013-02-01

    Ordered mesoporous Al2O3-SiO2-carbon nanocomposites have been synthesized via the direct triblock-copolymer self-assembly route using soluble phenolic resols as polymer precursors, aluminium chloride hexahydrate as an aluminum precursor, tetraethoxysilane as a silica precursor, and Pluronic F127 as a template. Characterization of XRD, N2 sorption isotherms, TEM, solid-state NMR, TG, and NH3-TPD techniques is used to investigate the mesostructure, pore properties, phase composition, metal incorporation state, and acidic properties. Ordered mesoporous nanocomposites have "reinforced concrete"-structured frameworks, in which the oxide and carbon components are microphase separated and homogenously dispersed inside pore walls. Al species are tetrahedrally incorporated into silica frameworks to compose the inorganic oxide compounds which provides acidic center. The nanocomposites have the ordered 2-D hexagonal mesostructure, high surface areas (291-360 m2/g), large pore volumes (0.25-0.42 cm3/g), large pore diameters (- 5 nm) and accessible acidic sites. PMID:23646686

  2. Synthesis of Inorganic Nanocomposites by Selective Introduction of Metal Complexes into a Self-Assembled Block Copolymer Template

    Directory of Open Access Journals (Sweden)

    Hiroaki Wakayama

    2015-01-01

    Full Text Available Inorganic nanocomposites have characteristic structures that feature expanded interfaces, quantum effects, and resistance to crack propagation. These structures are promising for the improvement of many materials including thermoelectric materials, photocatalysts, and structural materials. Precise control of the inorganic nanocomposites’ morphology, size, and chemical composition is very important for these applications. Here, we present a novel fabrication method to control the structures of inorganic nanocomposites by means of a self-assembled block copolymer template. Different metal complexes were selectively introduced into specific polymer blocks of the block copolymer, and subsequent removal of the block copolymer template by oxygen plasma treatment produced hexagonally packed porous structures. In contrast, calcination removal of the block copolymer template yielded nanocomposites consisting of metallic spheres in a matrix of a metal oxide. These results demonstrate that different nanostructures can be created by selective use of processes to remove the block copolymer templates. The simple process of first mixing block copolymers and magnetic nanomaterial precursors and then subsequently removing the block copolymer template enables structural control of magnetic nanomaterials, which will facilitate their applicability in patterned media, including next-generation perpendicular magnetic recording media.

  3. Self-Assembly of Nanocomposite Nonlinear Optical Materials for Photonic Devices Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This program targets the development of new highly anisotropic nonlinear optical nanocomposite materials for NASA and non-NASA applications in advanced photonic and...

  4. Coexistence of superconductivity and ferromagnetism in cluster-assembled Sn–Co nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Houben, K., E-mail: kelly.houben@fys.kuleuven.be [KU Leuven, Laboratory of Solid-State Physics and Magnetism, Celestijnenlaan 200 D, 3001 Leuven (Belgium); Menéndez, E. [KU Leuven, Instituut voor Kern-en Stralingsfysica, Celestijnenlaan 200 D, 3001 Leuven (Belgium); Romero, C.P. [KU Leuven, Laboratory of Solid-State Physics and Magnetism, Celestijnenlaan 200 D, 3001 Leuven (Belgium); Trekels, M. [KU Leuven, Instituut voor Kern-en Stralingsfysica, Celestijnenlaan 200 D, 3001 Leuven (Belgium); Picot, T. [KU Leuven, Laboratory of Solid-State Physics and Magnetism, Celestijnenlaan 200 D, 3001 Leuven (Belgium); Vantomme, A.; Temst, K. [KU Leuven, Instituut voor Kern-en Stralingsfysica, Celestijnenlaan 200 D, 3001 Leuven (Belgium); Van Bael, M.J. [KU Leuven, Laboratory of Solid-State Physics and Magnetism, Celestijnenlaan 200 D, 3001 Leuven (Belgium)

    2015-07-15

    Highlights: • Superconductivity in Sn–Co nanocomposites is tuned by morphology and composition. • Coexistence of superconductivity and ferromagnetism achieved up to high Co content. • Electronic coupling between grains is reduced by creating low transparency interfaces. • Insight in contribution of different pair breaking mechanisms in hybrid superconductor. - Abstract: The coexistence of superconductivity and ferromagnetism is investigated in granular Sn–Co nanocomposites. The nanocomposites have been prepared by co-deposition of Sn atoms and Co clusters, the morphology and composition of which can be tuned by varying the deposition rate of Co clusters relative to Sn atoms. Flat isolated Sn islands are obtained at zero or low Co cluster flux, while granular nanocomposites are formed with increasing Co cluster flux, reaching Co concentrations up to 44 vol.%. Interfaces with a low electronic transparency between superconductor and ferromagnet are obtained by a combination of the granular nature of the nanocomposites and the formation of Sn–Co alloys at the Sn/Co interfaces. The structure and composition of the nanocomposites have been thoroughly characterized by atomic force microscopy, X-ray diffraction and conversion electron Mössbauer spectroscopy. Over the entire Co concentration range, the hybrids show a ferromagnetic response. The superconducting phase boundary and the Meissner response depend on the morphology and composition of the nanocomposites. In particular, the superconducting critical temperature decreases with increasing Co concentration, while the Meissner response varies from a reversible to a strongly hysteretic behaviour depending on the morphology of the samples with different Co content. The persistence of superconductivity at high Co concentrations is attributed to a suppression of the superconducting proximity effect in these nanocomposites, which is ascribed to the low interface transparency between the Sn and Co components

  5. Synthesis and microwave absorption properties of electromagnetic functionalized Fe{sub 3}O{sub 4}-polyaniline hollow sphere nanocomposites produced by electrostatic self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yao-Feng; Ni, Qing-Qing, E-mail: nqq@zstu.edu.cn; Fu, Ya-Qin [Zhejiang Sci-Tech University, Key Laboratory of Advanced Textile Materials and Manufacturing Technology Ministry of Education (China); Natsuki, Toshiaki [Shinshu University, Department of Functional Machinery and Mechanics (Japan)

    2013-10-15

    Highly regulated Fe{sub 3}O{sub 4}-polyelectrolyte-modified polyaniline (Fe{sub 3}O{sub 4}-PE@PANI) hollow sphere nanocomposites were successfully synthesized using an electrostatic self-assembly approach. The morphology and structure of the Fe{sub 3}O{sub 4}-PE@PANI nanocomposites were characterized using field-emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The results showed that the as-prepared nanocomposites had well-defined sizes and shapes, and the average size is about 500 nm. The assembly process was investigated. Magnetization measurements showed that the saturation magnetization of the nanocomposites was 38.6 emu g{sup -1}. It was also found that the Fe{sub 3}O{sub 4}-PE@PANI nanocomposites exhibited excellent reflection loss abilities and wide response bandwidths compared with those of PANI hollow spheres in the range 0.5-15 GHz. The Fe{sub 3}O{sub 4}-PE@PANI nanocomposites are, therefore, promising for microwave absorption applications.

  6. A bisphenol A sensor based on novel self-assembly of zinc phthalocyanine tetrasulfonic acid-functionalized graphene nanocomposites

    International Nuclear Information System (INIS)

    In this work, a novel zinc phthalocyanine tetrasulfonic acid (ZnTsPc)-functionalized graphene nanocomposites (f-GN) was synthesized by a simple and efficient electrostatic self-assembly method, where the positive charged GN decorated by (3-aminopropyl) triethoxysilane (APTES) was self-assemblied with ZnTsPc, a two dimensional (2-D) molecules. It not only enhanced its stability for the hybrid structure, but also avoided the reaggregation of ZnTsPc or f-GN themselves. Based on layered ZnTsPc/f-GN nanocomposites modified glassy carbon electrode, a rapid and sensitive sensor was developed for the determination of bisphenol A (BPA). Under the optimal conditions, the oxidation peak current increased linearly with the concentration of BPA in the range of 5.0 × 10−8 to 4.0 × 10−6 M with correlation coefficient 0.998 and limits of detection 2.0 × 10−8 M. Due to high absorption nature for BPA and electron deficiency on ZnTsPc/f-GN, it presented the unique electron pathway arising from π–π stackable interaction during redox process for detecting BPA. The sensor exhibited remarkable long-term stability, good anti-interference and excellent electrocatalytic activity towards BPA detection. - Graphical abstract: 2-D ZnTsPc/f-GN architecture with high BPA absorption efficiency and excellent catalysis of central metal in ZnTsPc was highly promising for BPA sensor. - Highlights: • 2-D ZnTsPc/f-GN architecture was synthesized by electrostatic self-assembly method. • ZnTsPc/f-GN nanocomposites avoided the reaggregation of ZnTsPc and f-GN themselves. • An electrochemical BPA sensor was developed based on ZnTsPc/f-GN nanocomposites. • High absorption for BPA and electron deficiency on the surface of ZnTsPc/f-GN • The proposed sensor could be applied for detection of BPA in real samples

  7. A bisphenol A sensor based on novel self-assembly of zinc phthalocyanine tetrasulfonic acid-functionalized graphene nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Keyu [Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Institute of Research for Functional Materials, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350116 (China); Huang, Lei; Qi, Yongbo [Institute of Research for Functional Materials, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350116 (China); Huang, Caixia [Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Institute of Research for Functional Materials, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350116 (China); Pan, Haibo, E-mail: hbpan@fzu.edu.cn [Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Institute of Research for Functional Materials, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350116 (China); Du, Min [Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China)

    2015-04-01

    In this work, a novel zinc phthalocyanine tetrasulfonic acid (ZnTsPc)-functionalized graphene nanocomposites (f-GN) was synthesized by a simple and efficient electrostatic self-assembly method, where the positive charged GN decorated by (3-aminopropyl) triethoxysilane (APTES) was self-assemblied with ZnTsPc, a two dimensional (2-D) molecules. It not only enhanced its stability for the hybrid structure, but also avoided the reaggregation of ZnTsPc or f-GN themselves. Based on layered ZnTsPc/f-GN nanocomposites modified glassy carbon electrode, a rapid and sensitive sensor was developed for the determination of bisphenol A (BPA). Under the optimal conditions, the oxidation peak current increased linearly with the concentration of BPA in the range of 5.0 × 10{sup −8} to 4.0 × 10{sup −6} M with correlation coefficient 0.998 and limits of detection 2.0 × 10{sup −8} M. Due to high absorption nature for BPA and electron deficiency on ZnTsPc/f-GN, it presented the unique electron pathway arising from π–π stackable interaction during redox process for detecting BPA. The sensor exhibited remarkable long-term stability, good anti-interference and excellent electrocatalytic activity towards BPA detection. - Graphical abstract: 2-D ZnTsPc/f-GN architecture with high BPA absorption efficiency and excellent catalysis of central metal in ZnTsPc was highly promising for BPA sensor. - Highlights: • 2-D ZnTsPc/f-GN architecture was synthesized by electrostatic self-assembly method. • ZnTsPc/f-GN nanocomposites avoided the reaggregation of ZnTsPc and f-GN themselves. • An electrochemical BPA sensor was developed based on ZnTsPc/f-GN nanocomposites. • High absorption for BPA and electron deficiency on the surface of ZnTsPc/f-GN • The proposed sensor could be applied for detection of BPA in real samples.

  8. Structure and self-assembly of alkanethiols on III-V semiconductor (1 1 0) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Zerulla, D. [UCD Dublin, School of Physics, Science Centre North, Dublin 4 (Ireland)], E-mail: dominic.zerulla@ucd.ie; Chasse, T. [Universitaet Tuebingen, Institut fuer Physikalische und Theoretische Chemie, Auf der Morgenstelle 8, 72076 Tuebingen (Germany)

    2009-05-15

    We report on the self-assembly, binding, and structural properties of alkanethiol monolayers on III-V semiconductor (1 1 0) surfaces. In particular, the focus will be on medium size n-alkanethiols adsorbed on InP(1 1 0) and GaP(1 1 0) using soft X-ray photoelectron spectroscopy (SXPS), X-ray absorption near-edge structure (XANES) spectroscopy, scanning tunneling microscopy (STM) and electrochemical methods to reveal the binding and the inner structure of the systems. The results show that the sulfur from the thiol groups binds directly, under cleavage of its hydrogen atoms, to the indium atoms of the substrate while the hydrogen is bound to the phosphorous of the substrate. The angular (azimuthal and polar) resolved measurements reveal a substrate-dependent tilt of 34 deg. from normal for InP and 15 deg. for GaP. A unique feature observed on these systems is the complete alignment of the alkyl chains with respect to the azimuthal orientation. Further structural data confirm that this adsorbate system represents the case of a huge, single domain organic monolayer. We interprete this behaviour, which deviates strongly from the well known thiol films on gold, silver or copper, in terms of structural constraints and dangling-bond induced preorientation of the alkanethiol chains.

  9. Self-assembled ZnGa2O4–RGO nanocomposites and their enhanced adsorption and photocatalytic performance in water treatment

    International Nuclear Information System (INIS)

    Highlights: • ZnGa2O4–RGO nanocomposites by a self-assembly approach under facile solvothermal condition. • ZnGa2O4 NPs have a well-controlled size and uniform distribution. • The water treatment process is formed by two successive parts: adsorption and photocatalytic degradation. • The content of RGO sheets is crucial for optimizing the photocatalytic activity with a key value of 5%. - Abstract: ZnGa2O4 nanoparticles (NPs) have been successfully anchored onto reduced graphene oxide (RGO) nanosheets by a self-assembly approach under facile solvothermal condition. The as-synthesized ZnGa2O4–RGO nanocomposites were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The results reveal that ZnGa2O4 NPs with a well-controlled size and uniform distribution were successfully assembled onto RGO sheets. Moreover, both methylene blue (MB) and rhodamine B (RhB) were employed as model pollutants to evaluate the ability of as-prepared ZnGa2O4–RGO nanocomposites for wastewater treatment. The content of RGO sheets was found to be crucial for optimizing the photocatalytic activity of various nanocomposites with a key value of 5% beyond which the adsorption ability of ZnGa2O4–RGO nanocomposites for dyes dominates the process of water treatment

  10. CuAu–ZnO–graphene nanocomposite: A novel graphene-based bimetallic alloy-semiconductor catalyst with its enhanced photocatalytic degradation performance

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Hong [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Ye, Xiaoliang [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Duan, Kaiyue; Xue, Muyin; Du, Yongling; Ye, Weichun [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Wang, Chunming, E-mail: wangcm@lzu.edu.cn [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)

    2015-07-05

    Graphical abstract: In this work, we have successfully synthesized a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite, and which behaved an enhanced photocatalytic activity. - Highlights: • A bimetallic alloy-based catalyst: CuAu–ZnO–Gr is synthesized. • CuAu–ZnO–Gr behaves an enhanced photocatalytic activity. • The detailed explanation of photocatalytic mechanism of CuAu–ZnO–Gr. - Abstract: The bimetallic alloy CuAu nanoparticles (NPs) can produce more photogenerated electrons when compared with single metal Au NPs. Moreover, graphene (Gr) sheets can help the charge separation and slow down the recombination of the electron hole pairs of ZnO. Hence, a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite is synthesized. Due to the synergistic effect among CuAu NPs, ZnO nanopyramids, and Gr sheets, CuAu–ZnO–Gr behaves an enhanced photocatalytic activity for the photocatalytic degradation of synthetic colorants methyl orange (MO), methylene blue (MB), indigotin (IN), sunset yellow (SY), and tartrazine (TT) under the simulated sunlight irradiation. Furthermore, the apparent rate constants (k{sub app}) of MO, MB, IN, SY, and TT degradation are estimated respectively. In addition, the as-prepared CuAu–ZnO–Gr nanocomposite is characterized by X-ray diffraction, UV–vis spectrum, transmission electron microscopy, energy dispersive X-ray analysis (EDX), and EDX mapping. As a result of the facile synthesis route and the enhanced photocatalytic activity, this new material CuAu–ZnO–Gr can be a promising photocatalyst for the degradation of dyes.

  11. Self-Assembled Heteroepitaxial Oxide Nanocomposite for Photoelectrochemical Solar Water Oxidation

    OpenAIRE

    Cho, Seungho; Jang, Ji-Wook; Li, Leigang; Jian, Jie; Wang, Haiyan; MacManus-Driscoll, Judith L.

    2016-01-01

    We report on spontaneously phase ordered heteroepitaxial SrTiO3 (STO):ZnFe2O4 (ZFO) nanocomposite films that give rise to strongly enhanced photoelectrochemical solar water oxidation, consistent with enhanced photoinduced charge separation. The STO:ZFO nanocomposite yielded an enhanced photocurrent density of 0.188 mA/cm2 at 1.23 V vs a reversible hydrogen electrode, which was 7.9- and 2.6-fold higher than that of the plain STO film and ZFO film cases under 1-sun illumination, respectively. T...

  12. Three-Dimensional Self-Assembly of Core/Shell-Like Nanostructures for High-Performance Nanocomposite Permanent Magnets.

    Science.gov (United States)

    Li, Hailing; Li, Xiaohong; Guo, Defeng; Lou, Li; Li, Wei; Zhang, Xiangyi

    2016-09-14

    Core/shell nanostructures are fascinating for many advanced applications including strong permanent magnets, magnetic recording, and biotechnology. They are generally achieved via chemical approaches, but these techniques limit them to nanoparticles. Here, we describe a three-dimensional (3D) self-assembly of core/shell-like nanocomposite magnets, with hard-magnetic Nd2Fe14B core of ∼45 nm and soft-magnetic α-Fe shell of ∼13 nm, through a physical route. The resulting Nd2Fe14B/α-Fe core/shell-like nanostructure allows both large remanent magnetization and high coercivity, leading to a record-high energy product of 25 MGOe which reaches the theoretical limit for isotropic Nd2Fe14B/α-Fe nanocomposite magnets. Our approach is based on a sequential growth of the core and shell nanocrystals in an alloy melt. These results make an important step toward fabricating core/shell-like nanostructure in 3D materials.

  13. Preparation of Fe3O4@Au nano-composites by self-assembly technique for immobilization of glucose oxidase

    Institute of Scientific and Technical Information of China (English)

    WANG XianXiang; HUANG Shuo; Shan Zhi; YANG WanSheni

    2009-01-01

    Superparamagnetism amination nanocrystals Fe3O4 with 3-aminopropyltriethyloxy silane (APTES) were prepared by modified co-precipitation method. Next, 4-5 nm gold nanoparticles, prepared by classical Frens procedure, were coated on the surface of the amination Fe3O4 by self-assembly technology. The prepared Fe3O4@Au nanocomposite particles were investigated by transmission electron microscopy (TEM), UV-vis, infrared spectrum (FT-IR), and vibrating sample magnetometer (VSM) in order to eluci-date the morphology, optics and magnetic properties of the nanocomposites. Their uniform distribution of particle size, which is about 15 nm, and good magnetic responsiveness were observed. In view of the fact that Fe3O4 owns superparamagnetism and that nano-gold can readily combine with biological molecules, glucose oxidase (GOx) was chosen as a model to penetrate the condition of immobilizing enzyme, and enzymatic properties of resultant immobilized enzyme were studied as well. By systematic optimization, we established that at 28℃, and pH (5.5) and when mole ratio of Fe3O4:HAuCl4 was 0.5:1, the immobilization provided the best results. Finally, we are glad to find that the immobilized enzyme exhibits excellent thermostability in addition to its better stability than free enzyme. Thus, herein de-scribed immobilized enzyme could be used repeatedly with the assistance of an external magnetic field.

  14. Conducting Polymer Nanostructures and Nanocomposites with Carbon Nanotubes: Hierarchical Assembly by Molecular Electrochemistry, Growth Aspects and Property Characterization.

    Science.gov (United States)

    Gupta, Sanju; Price, Carson; Heintzman, Eli

    2016-01-01

    Conducting (or π-conjugated) polymers are promising materials for preparing supramolecular nano-structures and nanocomposites. We report controlled nanostructure syntheses of polypyrrole (PPy) and poylaniline (PANi) via electropolymerization (i.e., in-situ electrochemical anodic oxidation). The density, shape, caliber and thickness of self-assembled PPy micro-containers are regulated by electrochemical potential window for H2 bubbles and number of cyclic voltammetric (potentiodynamic) scans. Likewise, we employed amperometry, chronopotentiometry and potentiodynamic modes using hydrochloric acid as oxidizing agent to prepare PANi nanoparticles and nanotubules. We present our findings from the viewpoint of molecular electrochemistry with growth kinetic aspects yielding mechanistic details (initially forming dimers and oligomers as nucleating agents followed by polymer growth). Also targeted is forming nanocomposites with functionalized single- and multi-walled carbon nanotubes (FSWCNTs and FMWCNTs) as reinforced agent to optimize structural and functional properties. All of these novel nanomaterials are characterized using a range of complementary techniques to establish microscopic structure-property-function relationship. PMID:27398466

  15. BARK-MIMETIC LAYER-BY-LAYER ASSEMBLED MONTMORILLONITE/POLY(p-AMINOSTYRENE) FLEXIBLE NANOCOMPOSITES SHIELDING ATOMIC OXYGEN EROSION

    Institute of Scientific and Technical Information of China (English)

    Min Gao; Bing-jun Liu; Long-cheng Gao; Peng-gang Yin; Lei Jiang

    2013-01-01

    Inspired by the birch bark,which has multilayered structures,we fabricated layer-by-layer (LbL) assembled montmorillonite (MMT) and poly(p-aminostyrene) (PPAS) nanocomposites on cotton fiber curved surfaces to provide protection from atomic oxygen (AO) erosion.The multilayer coated fibers had high flexibility,uniformity,defect free,ease of preparation and low cost.The AO erosion durability has been dramatically enhanced which was evidenced by testing in the ground-based AO effects simulation facility.And the dimension and surface morphologies of the fibers observed by SEM had few changes,indicating excellent AO erosion resistant ability of the coatings.These results provide us a new method to design fibrous materials exposed directly in low earth orbit environment.

  16. Fabrication and characterization of Ag/polymer nanocomposite films through layer-by-layer self-assembly technique

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiaohong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School, Chinese Academy of Science, Beijing 100039 (China); Wang Jinqing [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhang Junyan [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: junyanzh@yahoo.com; Liu Bin; Zhou Jinfang [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School, Chinese Academy of Science, Beijing 100039 (China); Yang Shengrong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: sryang@lzb.ac.cn

    2007-07-31

    Multilayer nanocomposite films composed of negative charged Ag nanosized particles and cationic polyallylamine hydrochloride (PAH) molecules were fabricated on polymer modified single-crystal silicon and flat glass slides by a layer-by-layer (LBL) molecular self-assembly technique. The X-ray photoelectron spectroscopy analysis showed that the formed Ag particles successfully absorbed onto the positively charged surfaces. The atomic force microscopy image of a two-cycle Ag/PAH bilayer film showed that no surface damage or defects existed on the thin-films surface. The Ag particles were densely and homogeneously distributed on the surface and relatively uniform in size. Goniometry was employed to verify the assembly process and the water contact angles oscillated regularly, depending on the composition of the outermost layer. By using the LBL deposition technique, a molecular-level ordered multilayer film with the thickness up to 40 layers (20 bilayers) was obtained. Results from UV-vis spectroscopy and ellipsometry measurements revealed that the self-assembly of the Ag/PAH multilayer film was well quantitative and reproducible. Thus we can conclude that the consecutive LBL deposition technique is a feasible and effective way to produce multilayer film and control the surface properties.

  17. Fabrication and characterization of Ag/polymer nanocomposite films through layer-by-layer self-assembly technique

    International Nuclear Information System (INIS)

    Multilayer nanocomposite films composed of negative charged Ag nanosized particles and cationic polyallylamine hydrochloride (PAH) molecules were fabricated on polymer modified single-crystal silicon and flat glass slides by a layer-by-layer (LBL) molecular self-assembly technique. The X-ray photoelectron spectroscopy analysis showed that the formed Ag particles successfully absorbed onto the positively charged surfaces. The atomic force microscopy image of a two-cycle Ag/PAH bilayer film showed that no surface damage or defects existed on the thin-films surface. The Ag particles were densely and homogeneously distributed on the surface and relatively uniform in size. Goniometry was employed to verify the assembly process and the water contact angles oscillated regularly, depending on the composition of the outermost layer. By using the LBL deposition technique, a molecular-level ordered multilayer film with the thickness up to 40 layers (20 bilayers) was obtained. Results from UV-vis spectroscopy and ellipsometry measurements revealed that the self-assembly of the Ag/PAH multilayer film was well quantitative and reproducible. Thus we can conclude that the consecutive LBL deposition technique is a feasible and effective way to produce multilayer film and control the surface properties

  18. High-performance GaAs metal-insulator-semiconductor field-effect transistors enabled by self-assembled nanodielectrics

    Science.gov (United States)

    Lin, H. C.; Ye, P. D.; Xuan, Y.; Lu, G.; Facchetti, A.; Marks, T. J.

    2006-10-01

    High-performance GaAs metal-insulator-semiconductor field-effect-transistors (MISFETs) fabricated with very thin self-assembled organic nanodielectrics (SANDs), deposited from solution at room temperature, are demonstrated. A submicron gate-length depletion-mode n-channel GaAs MISFET with SAND thicknesses ranging from 5.5to16.5nm exhibit a gate leakage current density <10-5A/cm2 at a gate bias smaller than 3V, a maximum drain current of 370mA/mm at a forward gate bias of 2V, and a maximum intrinsic transconductance of 170mS/mm. The importance of appropriate GaAs surface chemistry treatments on SAND/GaAs interface properties is also presented. Application of SANDs to III-V compound semiconductors affords more opportunities to manipulate the complex III-V surface chemistry with broad materials options.

  19. Self-Assembled Heteroepitaxial Oxide Nanocomposite for Photoelectrochemical Solar Water Oxidation

    Science.gov (United States)

    2016-01-01

    We report on spontaneously phase ordered heteroepitaxial SrTiO3 (STO):ZnFe2O4 (ZFO) nanocomposite films that give rise to strongly enhanced photoelectrochemical solar water oxidation, consistent with enhanced photoinduced charge separation. The STO:ZFO nanocomposite yielded an enhanced photocurrent density of 0.188 mA/cm2 at 1.23 V vs a reversible hydrogen electrode, which was 7.9- and 2.6-fold higher than that of the plain STO film and ZFO film cases under 1-sun illumination, respectively. The photoelectrode also produced stable photocurrent and Faradaic efficiencies of H2 and O2 formation that were more than 90%. Incident-photon-to-current-conversion efficiency measurements, Tauc plots, Mott–Schottky plots, and electrochemical impedance spectroscopy measurements proved that the strongly enhanced photogenerated charge separation resulted from vertically aligned pseudosingle crystalline components, epitaxial heterojunctions, and a staggered band alignment of the components of the nanocomposite films. This study presents a completely new avenue for efficient solar energy conversion applications. PMID:27212792

  20. MEMS as low-cost high-volume semiconductor solutions: it's all in the packaging and assembly

    Science.gov (United States)

    Brown, Joe; Lutz, Markus; Partridge, Aaron; Gupta, Pavan; Radza, Eric

    2008-02-01

    Micro-electromechanical (MEMS) oscillators are now in production and shipping in quantity. Early development of micro mechanical devices provided the understanding that metal beams could be fabricated and they would resonate as a time reference. The issues of performance and price have prevented silicon entry into the quartz dominated market until recent developments in semiconductor processing and assembly. Today MEMS oscillators are the world's smallest programmable precision oscillators and are displacing quartz technology in the +/- 50 ppm accuracy spec. New oscillators extend the technology with spread spectrum, voltage control, and improved jitter performance. New ultra-thin packaging, made possible by the small encapsulated MEMS resonators, provides the word's thinnest precision oscillators.

  1. Mechanical and Thermal Characteristics of Bio-Nanocomposites Consisting of Poly-L-lactic Acid and Self-Assembling Siloxane Nanoparticles with Three Phases

    Directory of Open Access Journals (Sweden)

    Masatoshi Iji

    2012-01-01

    Full Text Available Biopolymer nanocomposites (bio-nanocomposite consisting of poly-L-lactic acid (PLLA and siloxane nanoparticles with three phases, a high-density siloxane phase (plural cores, an elastomeric silicone phase, and a caprolactone oligomer phase, were developed to increase the mechanical properties of PLLA. The nanoparticles, average size of 13 nm, were self-assembled by aggregation and condensation of an organosiloxane with three units: isocyanatepropyltrimethoxysilane (IPTS, polymethylpropyloxysiloxane (PMPS, and a caprolactone oligomer (CLO, which form each phase. The bio-nanocomposite was produced using PLLA and the nanoparticles. Bending and tensile testing showed that the use of these nanoparticles (5 wt% in PLLA greatly increases the tenacity (breaking strain of PLLA while maintaining its relatively high breaking (maximum strength. The elongation of the nanocomposite was more than twice that of PLLA while the elasticity modulus and breaking (maximum strength were comparable to those of PLLA. The nanoparticles also increased the impact strength of PLLA. The use of the nanoparticles almost did not show adverse affect on the thermal resistance of PLLA. The nanocomposite’s heat resistance indicated by the glass transition temperature and heat distortion temperature was fairly kept. The decomposition temperature of the nanocomposite somewhat increased.

  2. High temperature magnetic order in Zn1‑x Mn x SnSb2+MnSb nanocomposite ferromagnetic semiconductors

    Science.gov (United States)

    Kilanski, L.; Górska, M.; Ślawska-Waniewska, A.; Lewińska, S.; Szymczak, R.; Dynowska, E.; Podgórni, A.; Dobrowolski, W.; Ralević, U.; Gajić, R.; Romčević, N.; Fedorchenko, I. V.; Marenkin, S. F.

    2016-08-01

    We present studies of structural, magnetic, and electrical properties of Zn1‑x Mn x SnSb2+MnSb nanocomposite ferromagnetic semiconductors with the average Mn-content, \\bar{x} , changing from 0.027 up to 0.138. The magnetic force microscope imaging done at room temperature shows the presence of a strong signal coming from MnSb clusters. Magnetic properties show the paramagnet-ferromagnet transition with the Curie temperature, T C, equal to about 522 K and the cluster-glass behavior with the transition temperature, T CG, equal to about 465 K, both related to MnSb clusters. The magnetotransport studies show that all investigated samples are p-type semiconductors with high hole concentration, p, changing from 1021 to 1022 cm‑3. A large increase in the resistivity as a function of the magnetic field is observed at T  <  10 K and small magnetic fields, |B|<100 mT, for all the studied samples with a maximum amplitude of the magnetoresistance about 460% at T  =  1.4 K. The large increase in the resistivity is most probably caused by the appearance of the superconducting state in the samples at T  <  4.3 K.

  3. Self-assembled ZnGa{sub 2}O{sub 4}–RGO nanocomposites and their enhanced adsorption and photocatalytic performance in water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Huang, K. [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Zhao, X.S.; Li, Y.F.; Xu, X.; Liang, C.; Fan, D.Y.; Yang, H.J. [School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Zhang, R., E-mail: ruzhang@bupt.edu.cn [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Wang, Y.G. [School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Lei, M., E-mail: mlei@bupt.edu.cn [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2014-12-15

    Highlights: • ZnGa{sub 2}O{sub 4}–RGO nanocomposites by a self-assembly approach under facile solvothermal condition. • ZnGa{sub 2}O{sub 4} NPs have a well-controlled size and uniform distribution. • The water treatment process is formed by two successive parts: adsorption and photocatalytic degradation. • The content of RGO sheets is crucial for optimizing the photocatalytic activity with a key value of 5%. - Abstract: ZnGa{sub 2}O{sub 4} nanoparticles (NPs) have been successfully anchored onto reduced graphene oxide (RGO) nanosheets by a self-assembly approach under facile solvothermal condition. The as-synthesized ZnGa{sub 2}O{sub 4}–RGO nanocomposites were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The results reveal that ZnGa{sub 2}O{sub 4} NPs with a well-controlled size and uniform distribution were successfully assembled onto RGO sheets. Moreover, both methylene blue (MB) and rhodamine B (RhB) were employed as model pollutants to evaluate the ability of as-prepared ZnGa{sub 2}O{sub 4}–RGO nanocomposites for wastewater treatment. The content of RGO sheets was found to be crucial for optimizing the photocatalytic activity of various nanocomposites with a key value of 5% beyond which the adsorption ability of ZnGa{sub 2}O{sub 4}–RGO nanocomposites for dyes dominates the process of water treatment.

  4. Self-assembly of multiferroic core-shell particulate nanocomposites through DNA-DNA hybridization and magnetic field directed assembly of superstructures

    Directory of Open Access Journals (Sweden)

    Gollapudi Sreenivasulu

    2016-04-01

    Full Text Available Multiferroic composites of ferromagnetic and ferroelectric phases are of importance for studies on mechanical strain mediated coupling between the magnetic and electric subsystems. This work is on DNA-assisted self-assembly of superstructures of such composites with nanometer periodicity. The synthesis involved oligomeric DNA-functionalized ferroelectric and ferromagnetic nanoparticles, 600 nm BaTiO3 (BTO and 200 nm NiFe2O4 (NFO, respectively. Mixing BTO and NFO particles, possessing complementary DNA sequences, resulted in the formation of ordered core-shell heteronanocomposites held together by DNA hybridization. The composites were imaged by scanning electron microscopy and scanning microwave microscopy. The presence of heteroassemblies along with core-shell architecture is clearly observed. The reversible nature of the DNA hybridization allows for restructuring the composites into mm-long linear chains and 2D-arrays in the presence of a static magnetic field and ring-like structures in a rotating-magnetic field. Strong magneto-electric (ME coupling in as-assembled composites is evident from static magnetic field H induced polarization and low-frequency magnetoelectric voltage coefficient measurements. Upon annealing the nanocomposites at high temperatures, evidence for the formation of bulk composites with excellent cross-coupling between the electric and magnetic subsystems is obtained by H-induced polarization and low-frequency ME voltage coefficient. The ME coupling strength in the self-assembled composites is measured to be much stronger than in bulk composites with randomly distributed NFO and BTO prepared by direct mixing and sintering.

  5. Self-assembly of multiferroic core-shell particulate nanocomposites through DNA-DNA hybridization and magnetic field directed assembly of superstructures

    Science.gov (United States)

    Sreenivasulu, Gollapudi; Lochbiler, Thomas A.; Panda, Manashi; Srinivasan, Gopalan; Chavez, Ferman A.

    2016-04-01

    Multiferroic composites of ferromagnetic and ferroelectric phases are of importance for studies on mechanical strain mediated coupling between the magnetic and electric subsystems. This work is on DNA-assisted self-assembly of superstructures of such composites with nanometer periodicity. The synthesis involved oligomeric DNA-functionalized ferroelectric and ferromagnetic nanoparticles, 600 nm BaTiO3 (BTO) and 200 nm NiFe2O4 (NFO), respectively. Mixing BTO and NFO particles, possessing complementary DNA sequences, resulted in the formation of ordered core-shell heteronanocomposites held together by DNA hybridization. The composites were imaged by scanning electron microscopy and scanning microwave microscopy. The presence of heteroassemblies along with core-shell architecture is clearly observed. The reversible nature of the DNA hybridization allows for restructuring the composites into mm-long linear chains and 2D-arrays in the presence of a static magnetic field and ring-like structures in a rotating-magnetic field. Strong magneto-electric (ME) coupling in as-assembled composites is evident from static magnetic field H induced polarization and low-frequency magnetoelectric voltage coefficient measurements. Upon annealing the nanocomposites at high temperatures, evidence for the formation of bulk composites with excellent cross-coupling between the electric and magnetic subsystems is obtained by H-induced polarization and low-frequency ME voltage coefficient. The ME coupling strength in the self-assembled composites is measured to be much stronger than in bulk composites with randomly distributed NFO and BTO prepared by direct mixing and sintering.

  6. Assembling non-ferromagnetic materials to ferromagnetic architectures using metal-semiconductor interfaces

    Science.gov (United States)

    Ma, Ji; Liu, Chunting; Chen, Kezheng

    2016-01-01

    In this work, a facile and versatile solution route was used to fabricate room-temperature ferromagnetic fish bone-like, pteridophyte-like, poplar flower-like, cotton-like Cu@Cu2O architectures and golfball-like Cu@ZnO architecture. The ferromagnetic origins in these architectures were found to be around metal-semiconductor interfaces and defects, and the root cause for their ferromagnetism lay in charge transfer processes from metal Cu to semiconductors Cu2O and ZnO. Owing to different metallization at their interfaces, these architectures exhibited different ferromagnetic behaviors, including coercivity, saturation magnetization as well as magnetic interactions. PMID:27680286

  7. On a chaotic potential at the surface of a compensated semiconductor under conditions of the self-assembly of electrically active defects

    Energy Technology Data Exchange (ETDEWEB)

    Bondarenko, V. B., E-mail: enter@spbstu.ru; Filimonov, A. V. [St. Petersburg State Polytechnic University (Russian Federation)

    2015-09-15

    Natural irregularities of the electric potential on the surface of a semiconductor under conditions of the partial self-assembly of electrically active defects, i.e., on the formation of donor–acceptor pairs in depletion layers, are studied. The amplitude and character of the spatial distribution of the chaotic potential on the surface of a semiconductor in the cases of localized and delocalized states are determined. The dependence of the amplitude of the chaotic potential on the degree of compensation of the semiconductor is obtained.

  8. Hairy nanoparticle assemblies as one-component functional polymer nanocomposites: opportunities and challenges

    KAUST Repository

    Fernandes, Nikhil J.

    2013-03-01

    Over the past three decades, the combination of inorganic-nanoparticles and organic-polymers has led to a wide variety of advanced materials, including polymer nanocomposites (PNCs). Recently, synthetic innovations for attaching polymers to nanoparticles to create hairy nanoparticles (HNPs) has expanded opportunities in this field. In addition to nanoparticle compatibilization for traditional particle-matrix blending, neat-HNPs afford one-component hybrids, both in composition and properties, which avoids issues of mixing that plague traditional PNCs. Continuous improvements in purity, scalability, and theoretical foundations of structure-performance relationships are critical to achieving design control of neat-HNPs necessary for future applications, ranging from optical, energy, and sensor devices to lubricants, green-bodies, and structures. © 2013 Materials Research Society.

  9. Temperature-induced assembly of semiconductor nanocrystals into fractal architectures and thermoelectric power properties in Au/Ge bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Li Quanbao; Wang Jian; Jiao Zheng [Shanghai Applied Radiation Institute, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Wu Minghong, E-mail: mhwu@staff.shu.edu.cn [Shanghai Applied Radiation Institute, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Shek, Chan-Hung; Lawrence Wu, C.M.; Lai, Joseph K.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Chen Zhiwen, E-mail: cnzwchen@yahoo.com.cn [Shanghai Applied Radiation Institute, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)

    2011-08-15

    Highlights: > Ge fractal architectures were achieved by temperature-induced assembly. > The appearance of fractal architectures influences the thermoelectric power. > But it has little effect on the resistivity. > The values of the superlocalization exponent were within 1.22 {<=} {xi} {<=} 1.29. > It was higher than expected for two-dimension fractal system. - Abstract: Fractal architectures of semiconductor nanocrystals were successfully achieved by temperature-induced assembly of semiconductor nanocrystals in gold/germanium (Au/Ge) bilayer films. New assessment strategies of fractal architectures are of fundamental importance in the development of micro/nano-devices. Temperature-dependent properties including resistivity and thermoelectric power (TEP) of Au/Ge bilayer films with self-similar fractal patterns were investigated in detail. Experimental results indicated that the microstructure of Au film plays an important role in the characteristics of Au/Ge bilayer films after annealing and the crystallization processes of amorphous Ge accompany by fractal formation of Ge nanocrystals via temperature-induced assembly. The appearance of fractal architectures has significantly influence on the TEP but little effect on the resistivity of the annealed bilayer film. By analysis of the data, we found that the values of superlocalization exponent are within 1.22 {<=} {xi} {<=} 1.29, which are higher than expected for two-dimension fractal systems. The results provided possible evidence for the superlocalization on fractal architectures in Au/Ge bilayer films. The TEP measurements are considered a more effective method than the conductivity for investigating superlocalization in a percolating system.

  10. Layer-by-layer assembly of nanocomposite films with thickness up to hundreds of nanometers

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ling-de; YAN Yu-hua; YU Hai-hu; GU Er-dan; JIANG De-sheng

    2006-01-01

    Polyelectrolyte/polyelectrolyte, organic molecule/colloidal CdS and polyelectrolyte/MWCNT films were fabricated via the layer-by-layer assembling technique. The assembled films were characterized by UV-vis spectrophotometer, X-ray diffractometry,nano profilometer and scanning electron microscopy. The results demonstrate that the layer-by-layer assembling technique can be used to make the nanoscaled films from polyelectrolytes and thicker composite films from suitable precursor materials. Both organic molecule/colloidal CdS films and PEI/MWCNT films with thickness of hundreds of nanometers were obtained. For the organic molecule/colloidal CdS films, a reasonable explanation for the result is that both the organic molecules and the CdS particles aggregate in the films. For the PEI/MWCNT films, obviously, it is the MWCNT that makes the great contribution to the film thickness.

  11. Fabrication of Au/SiO2 Nanocomposite Films by Self-Assembly Multilayer Method

    Institute of Scientific and Technical Information of China (English)

    Haihu YU; Honghui LI; Desheng JIANG; Xiaoyao CHEN; Enyu YANG

    2004-01-01

    Gold colloid was prepared by chemical reduction of hydrogen tetrachloroaurate, polyelectrolyte/gold nanoparticle/silica nanopar ticle composite films were fabricated via an electrostatic self-assembly multilayer method, and composite films of gold nanopar ticle dispersed in silica matrix were formed by heat-treating the polyelectrolyte/gold nanoparticle/silica nanoparticle composite films to eliminate the polyelectrolyte. The obtained composite films were investigated with UV-vis, TEM, AFM and XRD. Theresults show that the self-assembly multilayer method is a promising process to produce composite films of gold nanoparticledispersed in organic and/or inorganic matrixes.

  12. Preparation of MIL-53(Fe)-Reduced Graphene Oxide Nanocomposites by a Simple Self-Assembly Strategy for Increasing Interfacial Contact: Efficient Visible-Light Photocatalysts.

    Science.gov (United States)

    Liang, Ruowen; Shen, Lijuan; Jing, Fenfen; Qin, Na; Wu, Ling

    2015-05-13

    In this work, MIL-53(Fe)-reduced graphene oxide (M53-RGO) nanocomposites have been successfully fabricated by a facile and efficient electrostatic self-assembly strategy for improving the interfacial contact between RGO and the MIL-53(Fe). Compared with D-M53-RGO (direct synthesis of MIL-53(Fe)-reduced graphene oxide nanocomposites via one-pot solvothermal approach), M53-RGO nanocomposites exhibit improved photocatalytic activity compared with the D-M53-RGO under identical experimental conditions. After 80 min of visible light illumination (λ ≥ 420 nm), the reduction ratio of Cr(VI) is rapidly increased to 100%, which is also higher than that of reference sample (N-doped TiO2). More significantly, the M53-RGO nanocomposites are proven to perform as bifunctional photocatalysts with considerable activity in the mixed systems (Cr(VI)/dyes) under visible light, which made it a potential candidate for industrial wastewater treatment. Combining with photoelectrochemical analyses, it could be revealed that the introduction of RGO would minimize the recombination of photogenerated electron-hole pairs. Additionally, the effective interfacial contact between MIL-53(Fe) and RGO surface would further accelerate the transfer of photogenerated electrons, leading to the enhancement of photocatalytic activity of M53-RGO toward photocatalytic reactions. Finally, a possible photocatalytic reaction mechanism is also investigated in detail. PMID:25894300

  13. Tips and tricks for the assembly of a Corynebacterium pseudotuberculosis genome using a semiconductor sequencer

    DEFF Research Database (Denmark)

    Ramos, Rommel Thiago Jucá; Carneiro, Adriana Ribeiro; Soares, Siomar de Castro;

    2013-01-01

    New sequencing platforms have enabled rapid decoding of complete prokaryotic genomes at relatively low cost. The Ion Torrent platform is an example of these technologies, characterized by lower coverage, generating challenges for the genome assembly. One particular problem is the lack of genomes ...... is not a traditional biological model such as Escherichia coli.......New sequencing platforms have enabled rapid decoding of complete prokaryotic genomes at relatively low cost. The Ion Torrent platform is an example of these technologies, characterized by lower coverage, generating challenges for the genome assembly. One particular problem is the lack of genomes...... that enable reference-based assembly, such as the one used in the present study, Corynebacterium pseudotuberculosis biovar equi, which causes high economic losses in the US equine industry. The quality treatment strategy incorporated into the assembly pipeline enabled a 16-fold greater use of the sequencing...

  14. Influence of a self-assembled monolayer on indium-zinc-oxide semiconductor thin-film transistors

    International Nuclear Information System (INIS)

    The fabrication of an active-matrix liquid-crystal display by using printing processes offers the potential to reduce the number of photolithography steps and the manufacturing costs. In this study, we prepare the indium-zinc-oxide (IZO) thin-film transistors (TFTs) by using non-vacuum processes such as inkjet printing. The self-assembled monolayers of hexadecanethiol (HDT) on the surface of the oxide semiconductor prior to the inkjet printing of Ag were employed to modify the electric barrier between the IZO and the printed Ag. The field-effect mobility of the IZO TFTs with 0.5-mM HDT treatments and with the inkjet-printed Ag electrodes that were investigated by using their current-voltage characteristics was approximately 0.36 cm2/Vs.

  15. Construction of carbon quantum dots/proton-functionalized graphitic carbon nitride nanocomposite via electrostatic self-assembly strategy and its application

    Science.gov (United States)

    Jian, Xuan; Liu, Xian; Yang, Hui-min; Li, Jia-gang; Song, Xiu-li; Dai, Hong-yan; Liang, Zhen-hai

    2016-05-01

    Carbon quantum dots (CQDs) and graphitic carbon nitride (g-C3N4), as advanced metal-free material catalysts have been the focus of considerable attention because of their superior photocatalytic activities. In this study, we developed a novel approach to obtain CQDs/g-C3N4 nanocomposite with effective interfacial contact by incorporating negatively charged CQDs and tailor-made proton-functionalized g-C3N4via the electrostatic self-assembly strategy. Then, the morphology and microstructure of the new nanocomposite were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The CQDs and proton-functionalized g-C3N4 nanocomposite exhibited excellent electron transfer properties though electrochemical impedance spectroscopy (EIS), significantly enhanced photoactivity in the photoelectrochemical i-t curve test and degradation of methylene blue solution under visible light irradiation. These results demonstrated that the electrostatic self-assembly strategy process is a promising method of fabricating uniform metal-free material catalysts for an extensive range of applications.

  16. Improved performance of diatomite-based dental nanocomposite ceramics using layer-by-layer assembly

    Directory of Open Access Journals (Sweden)

    Lu X

    2012-04-01

    Full Text Available Xiaoli Lu1,2, Yang Xia1, Mei Liu1, Yunzhu Qian3, Xuefeng Zhou4, Ning Gu4, Feimin Zhang1,41Institute of Stomatology, Nanjing Medical University, Nanjing, 2Nantong Stomatological Hospital, Nantong, 3Center of Stomatology, The Second Affiliated Hospital of Suzhou University, Suzhou, 4Suzhou Institute, Southeast University, Suzhou, People's Republic of ChinaAbstract: To fabricate high-strength diatomite-based ceramics for dental applications, the layer-by-layer technique was used to coat diatomite particles with cationic [poly(allylamine hydrochloride] and anionic [poly(sodium 4-styrenesulfonate] polymers to improve the dispersion and adsorption of positively charged nano-ZrO2 (zirconia as a reinforcing agent. The modified diatomite particles had reduced particle size, narrower size distribution, and were well dispersed, with good adsorption of nano-ZrO2. To determine the optimum addition levels for nano-ZrO2, ceramics containing 0, 20, 25, 30, and 35 wt% nano-ZrO2 were sintered and characterized by the three-point bending test and microhardness test. In addition to scanning electron microscopy, propagation phase-contrast synchrotron X-ray microtomography was used to examine the internal structure of the ceramics. The addition of 30 wt% nano-ZrO2 resulted in the highest flexural strength and fracture toughness with reduced porosity. Shear bond strength between the core and veneer of our diatomite ceramics and the most widely used dental ceramics were compared; the shear bond strength value for the diatomite-based ceramics was found to be significantly higher than for other groups (P < 0.05. Our results show that diatomite-based nanocomposite ceramics are good potential candidates for ceramic-based dental materials.Keywords: layer-by-layer, diatomite, nanoceramics, zirconia (ZrO2, dental materials

  17. Interplay between polymer chain conformation and nanoparticle assembly in model industrial silica/rubber nanocomposites.

    Science.gov (United States)

    Bouty, Adrien; Petitjean, Laurent; Chatard, Julien; Matmour, Rachid; Degrandcourt, Christophe; Schweins, Ralf; Meneau, Florian; Kwasńiewski, Paweł; Boué, François; Couty, Marc; Jestin, Jacques

    2016-01-01

    The question of the influence of nanoparticles (NPs) on chain dimensions in polymer nanocomposites (PNCs) has been treated mainly through the fundamental way using theoretical or simulation tools and experiments on well-defined model PNCs. Here we present the first experimental study on the influence of NPs on the polymer chain conformation for PNCs designed to be as close as possible to industrial systems employed in the tire industry. PNCs are silica nanoparticles dispersed in a styrene-butadiene-rubber (SBR) matrix whose NP dispersion can be managed by NP loading with interfacial coatings or coupling additives usually employed in the manufacturing mixing process. We associated specific chain (d) labeling, and the so-called zero average contrast (ZAC) method, with SANS, in situ SANS and SAXS/TEM experiments to extract the polymer chain scattering signal at rest for non-cross linked and under stretching for cross-linked PNCs. NP loading, individual clusters or connected networks, as well as the influence of the type, the quantity of interfacial agent and the influence of the elongation rate have been evaluated on the chain conformation and on its related deformation. We clearly distinguish the situations where the silica is perfectly matched from those with unperfected matching by direct comparison of SANS and SAXS structure factors. Whatever the silica matching situation, the additive type and quantity and the filler content, there is no significant change in the polymer dimension for NP loading up to 15% v/v within a range of 5%. One can see an extra scattering contribution at low Q, as often encountered, enhanced for non-perfect silica matching but also visible for perfect filler matching. This contribution can be qualitatively attributed to specific h or d chain adsorption on the NP surface inside the NP cluster that modifies the average scattering neutron contrast of the silica cluster. Under elongation, NPs act as additional cross-linking junctions

  18. Quantum size effect on the layer by layer assembly of PbTe–InSe multilayer nanocomposite structures

    Energy Technology Data Exchange (ETDEWEB)

    Parvathi, M. Manonmani; Arivazhagan, V. [Department of Physics, Karunya University, Coimbatore 641 114 (India); Rajesh, S., E-mail: drsrajesh@karunya.edu [Department of Nanoscience and Technology, Karunya University, Coimbatore 641 114 (India)

    2015-10-15

    PbTe–InSe multilayer nanocomposite structures were prepared by thermal evaporation method using layer by layer assembly with different PbTe nanocrystal (NCs) layer thicknesses ranges from 5 to 20 nm. Cross sectional transmission electron microscopy images divulge the formation of PbTe NCs embedded within InSe matrix as an ordered PbTe–InSe multilayer structure. X-ray and electron beam diffractions from the multilayer structure exhibit eminent peak at (2 0 0) plane analogous to face-centred cubic PbTe. The absorption onset significantly blue shifted as long as 3 nm PbTe NCs were embedded in InSe matrix. The observed band gap is correlated with theoretically predicted effective band gap of three dimensionally confined PbTe NCs which confirm size dependent quantum confinement effect. PL spectra show dominant single emission at 1.6 eV corresponding to the band edge emission of PbTe NCs. The prospects to use this structure in p-i-n junction quantum dot solar cells are discussed. - Graphical abstract: A graphical abstract to illustrate (a) schematic view of the PbTe–InSe multilayer structure. (b) and (c) are the cross sectional TEM and AFM image of the single layer PbTe NCs on InSe matrix, respectively. - Highlights: • PbTe Nanocrystals embedded in an amorphous InSe matrix by thermal evaporation. • Array of 3D confined PbTe NCs was obtained from layer by layer deposition. • Growth of isolated PbTe NCs were observed from TEM and AFM. • Blue shift from absorption spectra and quantum confined PL emission were observed. • Use of this structure in next generation solar cells were discussed.

  19. Electronic structure and self-assembly of cross-linked semiconductor nanocrystal arrays

    International Nuclear Information System (INIS)

    We studied the electronic level structure of assemblies of InAs quantum dots and CdSe nanorods cross-linked by 1,4-phenylenediamine molecules using scanning tunneling spectroscopy. We found that the bandgap in these arrays is reduced with respect to the corresponding ligand-capped nanocrystal arrays. In addition, a pronounced sub-gap spectral structure commonly appeared which can be attributed to unpassivated nanocrystal surface states or associated with linker-molecule-related levels. The exchange of the ligands by the linker molecules also affected the structural array properties. Most significantly, clusters of close-packed standing CdSe nanorods were formed

  20. Percolated conductive polyaniline-clay nanocomposite in polyvinyl chloride through the combined approach porous template and self-assembly

    OpenAIRE

    J. D. Sudha; S. Sivakala; Chandrakanth, C. K.; K. S. Neethu; K. N. Rohini; Ramakrishnan, R.

    2014-01-01

    In this paper, we are reporting a novel strategy for the preparation of conductive polyaniline-clay nanocomposite in Polyvinylchloride (PVC) matrix by admicellar emulsion polymerization using a low cost renewable resource based surfactant cum dopant. The highly oriented percolated network of polyaniline-clay nanocomposite in PVC matrix was revealed from the studies made by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Fourier transform infrared spectroscopy (FTIR) resu...

  1. Role of block copolymer adsorption versus bimodal grafting on nanoparticle self-assembly in polymer nanocomposites.

    Science.gov (United States)

    Zhao, Dan; Di Nicola, Matteo; Khani, Mohammad M; Jestin, Jacques; Benicewicz, Brian C; Kumar, Sanat K

    2016-09-14

    We compare the self-assembly of silica nanoparticles (NPs) with physically adsorbed polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymers (BCP) against NPs with grafted bimodal (BM) brushes comprised of long, sparsely grafted PS chains and a short dense carpet of P2VP chains. As with grafted NPs, the dispersion state of the BCP NPs can be facilely tuned in PS matrices by varying the PS coverage on the NP surface or by changes in the ratio of the PS graft to matrix chain lengths. Surprisingly, the BCP NPs are remarkably better dispersed than the NPs tethered with bimodal brushes at comparable PS grafting densities. We postulate that this difference arises because of two factors inherent in the synthesis of the NPs: In the case of the BCP NPs the adsorption process is analogous to the chains being "grafted to" the NP surface, while the BM case corresponds to "grafting from" the surface. We have shown that the "grafted from" protocol yields patchy NPs even if the graft points are uniformly placed on each particle. This phenomenon, which is caused by chain conformation fluctuations, is exacerbated by the distribution function associated with the (small) number of grafts per particle. In contrast, in the case of BCP adsorption, each NP is more uniformly coated by a P2VP monolayer driven by the strongly favorable P2VP-silica interactions. Since each P2VP block is connected to a PS chain we conjecture that these adsorbed systems are closer to the limit of spatially uniform sparse brush coverage than the chemically grafted case. We finally show that the better NP dispersion resulting from BCP adsorption leads to larger mechanical reinforcement than those achieved with BM particles. These results emphasize that physical adsorption of BCPs is a simple, effective and practically promising strategy to direct NP dispersion in a chemically unfavorable polymer matrix. PMID:27502154

  2. Self-assembly of semiconductor organogelator nanowires for photoinduced charge separation.

    Science.gov (United States)

    Wicklein, André; Ghosh, Suhrit; Sommer, Michael; Würthner, Frank; Thelakkat, Mukundan

    2009-05-26

    We investigated an innovative concept of general validity based on an organogel/polymer system to generate donor-acceptor nanostructures suitable for charge generation and charge transport. An electron conducting (acceptor) perylene bisimide organogelator forms nanowires in suitable solvents during gelation process. This phenomenon was utilized for its self-assembly in an amorphous hole conducting (donor) polymer matrix to realize an interpenetrating donor-acceptor interface with inherent morphological stability. The self-assembly and interface generation were carried out either stepwise or in a single-step. Morphology of the donor-acceptor network in thin films obtained via both routes were studied by a combination of scanning electron microscopy and atomic force microscopy. Additionally, photoinduced charge separation and charge transport in these systems were tested in organic solar cells. Fabrication steps of multilayer organogel/polymer photovoltaic devices were optimized with respect to morphology and surface roughness by introducing additional smoothening layers and charge injection/blocking layers. An inverted cell geometry was used here in which electrons are collected at the bottom electrode and holes at the top electrode. The simultaneous preparation of the interface exhibits almost 3-fold improvement in device characteristics compared to the successive method. The device characteristics under AM1.5 spectral conditions and 100 mW/cm(2) for the simultaneous preparation route are short circuit current J(sc) = 0.28 mA cm(-2), open circuit voltage V(OC) = 390 mV, fill factor FF = 38%, and a power conversion efficiency eta = 0.041%. PMID:19408933

  3. Spectroscopy of size dependent many-particle effects in single self-assembled semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Dal Savio, C.

    2006-02-20

    Single InAs quantum dots (QDs) grown with the Stranski-Krastanov method in a In{sub 0.12}Ga{sub 0.88}As quantum well embedded in GaAs and emitting in the near infrared have been optically investigated. To perform QD spectroscopy at low temperatures a very stable micro-photoluminescence ({mu}-PL) microscope set-up fully integrated in a liquid helium (LHe) cryostate has been successfully developed. The system is based on the cold finger technique and a Fourier Transform (FT) spectrometer combined with a nitrogen cooled Ge detector. Photoluminescence of the QDs was excited non resonantly with a He-Ne laser and single dot spectroscopy was carried out at temperatures below 60 K. The experimental set-up allows mapping of the optical emission by recording spectra for every point of a scan grid. This mapping mode is used to acquire optical images and to locate a particular dot for investigation. Series of measurement on a single QD were normally performed over a long time (from a few days to a week), with the need of daily adjustment in the sub-micrometer range. At low excitation power a single sharp line (E{sub x}) arising from recombination of a single exciton in the dot is observed. Varying the excitation density the spectra become more complex, with appearance of the biexciton emission line (E{sub xx}) on the lower energies side of the E{sub x} line, followed by emission from excitons occupying higher shells in the dot. Measured biexciton binding energies and power dependence are in good agreement with values reported in the literature. The temperature dependence of the optical emission was investigated. The energy shows the characteristic decrease related to the shrinking of the semiconductor band gap, while the linewidth evolution is compatible with broadening due to coupling with acoustic and optical phonons. A statistics of biexciton binding energies over a dozen of dots was acquired and the results compared with single QD spectroscopy data available in the

  4. Controlling the assembly of graphene based nanosheets within a rubber matrix: Nanocomposite morphology probed by measuring gas permeation and dielectric properties

    Science.gov (United States)

    Scherillo, G.; Lavorgna, M.; De Luna, M. Salzano; Filippone, G.; Buonocore, G.; Xia, H.; Zhan, Y.; Mensitieri, G.

    2016-05-01

    Self-assembling of reduced graphene oxide (RGO) and graphene oxide (GO) platelets, as a tailored interconnected network within natural rubber and butyl rubber matrices, is proposed as a mean for obtaining nanocomposites with significantly enhanced functional properties as compared to unloaded rubber, i.e. gas barrier properties and electric conductivity, even at very low filler contents. Interestingly, the prescribed spatial arrangement of the nanoparticles (`segregated arrangement') results to be much more effective in improving properties than homogeneous dispersion (`not segregated' arrangement) of platelets, even at low loadings. The `segregated' structure originates from the confinement of platelets within the interstices of the coagulated latex particles, which act as a template for the network formation. The platelets are assembled on the latex particles giving rise to spheres with a core-shell structure, with a partial or complete covering depending on graphene amount. Conversely, the `not-segregated' structure is obtained by destroying this interconnected network by further processing the nanocomposite masterbatch via twin-roll mixing, thus determining a uniform orientation of exfoliated platelets.

  5. Influence of the Surfactant Nature on the Occurrence of Self-Assembly between Rubber Particles and Thermally Reduced Graphite Oxide during the Preparation of Natural Rubber Nanocomposites

    Directory of Open Access Journals (Sweden)

    Héctor Aguilar-Bolados

    2015-01-01

    Full Text Available The natural rubber (NR latex consists of polymer particles charged negatively due to the adsorbed phospholipids and proteins molecules. The addition of stable aqueous suspension of thermally reduced graphite oxide (TRGO stabilized by ionic surfactants to NR latex can favor the occurrence of interaction between the stabilized TRGO and NR particles. Herein, the use of two surfactants of different nature, namely, sodium dodecyl sulfate (SDS and dodecyltrimethylammonium bromide (DTAB, for the preparation of (TRGO/NR nanocomposites, is reported. Zeta potential and particle size measurements indicated that the use of DTAB as cationic surfactant results in the flocculation of NR particles and promoted the formation of ion-pair interactions between TRGO and the proteins and/or phospholipids present on the NR surface. This indicates that the use of DTAB can promote a self-assembly phenomenon between TRGO with adsorbed DTAB molecules and NR particles. The occurrence of self-assembly phenomenon allows obtaining homogenous dispersion of TRGO particles in the polymer matrix. The TRGO/NR nanocomposites prepared by the use of DTAB exhibited superior mechanical properties and excellent electrical conductivities reaching values of stress at 500% strain of 3.02 MPa and 10−4 S/cm, respectively.

  6. Dispersions of Semiconductor Nanoparticles in Thermotropic Liquid Crystal: From Optical Modification to Assisted Self-Assembly

    Science.gov (United States)

    Rodarte, Andrea L.

    The interaction of semiconducting quantum dot nanoparticles (QDs) within thermotropic liquid crystalline (LC) materials are studied in this thesis. LC materials are ideal for bottom-up organization of nanoparticles as an active matrix that can be externally manipulated via electric or magnetic fields. In addition, the optical properties of QDs can be modified by the surrounding LC resulting in novel devices such as a quantum dot/liquid crystal laser. The first system studies the dispersion of spherical nanoparticles in the phase. The dispersion is investigated with the use of polarized optical microscopy, fluorescence microscopy and confocal scanning microscopy. Quantum dots well dispersed in the isotropic phase are expelled from ordered domains of LC at the phase transition. Under controlled conditions, the majority of QDs in the system can form ordered three dimensional assemblies that are situated at defect points in the liquid crystal. The internal order of the assemblies is probed utilizing Forster resonance energy transfer (FRET), combined with small angle X-ray scattering (SAXS). Furthermore, the location of these assemblies can be predetermined with the use of beads as defect nucleation points in the cell. The interaction of QDs in a cholesteric liquid crystal (CLC) is also investigated. The reflection band created by the periodic change of index of refraction in a planar aligned CLC acts as a 1-D photonic cavity when the CLC is doped with a low concentration of QDs. A Cano-wedge cell varies the pitch of the CLC leading to the formation of Grandjean steps. This spatially tunes the photonic stop band, changing the resonance condition and continuously altering both the emission wavelength and polarization state of the QD ensemble. Using high resolution spatially and spectrally resolved photoluminescence measurements, the emission is shown to be elliptically polarized and that the tilt of the ellipse, while dependent on the emission wavelength, additionally

  7. Effects of nanoassembly on the optoelectronic properties of cadmium telluride - zinc oxide nanocomposite thin films for use in photovoltaic devices

    Science.gov (United States)

    Beal, Russell Joseph

    Quantum-scale semiconductors embedded in an electrically-active matrix have the potential to improve photovoltaic (PV) device power conversion efficiencies by allowing the solar spectral absorption and photocarrier transport properties to be tuned through the control of short and long range structure. In the present work, the effects of phase assembly on quantum confinement effects and carrier transport were investigated in CdTe - ZnO nanocomposite thin films for use as a spectrally sensitized n-type heterojunction element. The nanocomposites were deposited via a dual-source, sequential radio-frequency (RF) sputter technique that offers the unique opportunity for in-situ control of the CdTe phase spatial distribution within the ZnO matrix. The manipulation of the spatial distribution of the CdTe nanophase allowed for variation in the electromagnetic coupling interactions between semiconductor domains and accompanying changes in the effective carrier confinement volume and associated spectral absorption properties. Deposition conditions favoring CdTe connectivity had a red shift in absorption energy onset in comparison to phase assemblies with a more isolated CdTe phase. While manipulating the absorption properties is of significant interest, the electronic behavior of the nanocomposite must also be considered. The continuity of both the matrix and the CdTe influenced the mobility pathways for carriers generated within their respective phases. Photoconductivity of the nanocomposite, dependent upon the combined influences of nanostructure-mediated optical absorption and carrier transport path, increased with an increased semiconductor nanoparticle number density along the applied field direction. Mobility of the carriers in the nanocomposite was further mediated by the interface between the ZnO and CdTe nanophases which acts as a source of carrier scattering centers. These effects were influenced by low temperature annealing of the nanocomposite which served to

  8. In vitro investigation of methylene blue-bearing, electrostatically assembled aptamer-silica nanocomposites as potential photodynamic therapeutics.

    Science.gov (United States)

    Ding, Tian-Shyng; Huang, Xin-Chun; Luo, Yun-Ling; Hsu, Hsin-Yun

    2015-11-01

    Photodynamic therapy, that is, excitation of a photosensitizer with light to generate reactive oxygen species such as singlet oxygen, has emerged as a noninvasive technique for cancer theranostics. However, the clinical use of many photosensitizers is impeded by their hydrophobicity, the nonspecific damage they cause to normal tissues, and their susceptibility to environmental degradation. In this study, we developed a simple electrostatic adsorption strategy to fabricate aptamer-silica nanocomposites by sequentially functionalizing nanocomposites with the cell surface-associated mucin 1 aptamer for tumor targeting and a hydrophilic photosensitizer, methylene blue, for photodynamic therapy applications. We investigated the relationship between the biophysical properties and cellular uptake of such nanocomposites to improve their formulation. Effective generation of singlet oxygen was achieved with a low photosensitizer dosage (0.5 μM) and a short, low-power irradiation (1 min, 10 mW/cm(2)). With the current strategy, the efficiency of photodynamic therapy was determined by the cellular uptake of nanocomposites and the targeting molecules used.

  9. An enzymatically-sensitized sequential and concentric energy transfer relay self-assembled around semiconductor quantum dots

    Science.gov (United States)

    Samanta, Anirban; Walper, Scott A.; Susumu, Kimihiro; Dwyer, Chris L.; Medintz, Igor L.

    2015-04-01

    The ability to control light energy within de novo nanoscale structures and devices will greatly benefit their continuing development and ultimate application. Ideally, this control should extend from generating the light itself to its spatial propagation within the device along with providing defined emission wavelength(s), all in a stand-alone modality. Here we design and characterize macromolecular nanoassemblies consisting of semiconductor quantum dots (QDs), several differentially dye-labeled peptides and the enzyme luciferase which cumulatively demonstrate many of these capabilities by engaging in multiple-sequential energy transfer steps. To create these structures, recombinantly-expressed luciferase and the dye-labeled peptides were appended with a terminal polyhistidine sequence allowing for controlled ratiometric self-assembly around the QDs via metal-affinity coordination. The QDs serve to provide multiple roles in these structures including as central assembly platforms or nanoscaffolds along with acting as a potent energy harvesting and transfer relay. The devices are activated by addition of coelenterazine H substrate which is oxidized by luciferase producing light energy which sensitizes the central 625 nm emitting QD acceptor by bioluminescence resonance energy transfer (BRET). The sensitized QD, in turn, acts as a relay and transfers the energy to a first peptide-labeled Alexa Fluor 647 acceptor dye displayed on its surface. This dye then transfers energy to a second red-shifted peptide-labeled dye acceptor on the QD surface through a second concentric Förster resonance energy transfer (FRET) process. Alexa Fluor 700 and Cy5.5 are both tested in the role of this terminal FRET acceptor. Photophysical analysis of spectral profiles from the resulting sequential BRET-FRET-FRET processes allow us to estimate the efficiency of each of the transfer steps. Importantly, the efficiency of each step within this energy transfer cascade can be controlled to

  10. Direct-current and radio-frequency characterizations of GaAs metal-insulator-semiconductor field-effect transistors enabled by self-assembled nanodielectrics

    Science.gov (United States)

    Lin, H. C.; Kim, S. K.; Chang, D.; Xuan, Y.; Mohammadi, S.; Ye, P. D.; Lu, G.; Facchetti, A.; Marks, T. J.

    2007-08-01

    Direct-current and radio-frequency characterizations of GaAs metal-insulator-semiconductor field-effect transistors (MISFETs) with very thin self-assembled organic nanodielectrics (SANDs) are presented. The application of SAND on compound semiconductors offers unique opportunities for high-performance devices. Thus, 1μm gate-length depletion-mode n-channel SAND/GaAs MISFETs exhibit low gate leakage current densities of 10-2-10-5A/cm2, a maximum drain current of 260mA/mm at 2V forward gate bias, and a maximum intrinsic transconductance of 127mS/mm. These devices achieve a current cutoff frequency (fT) of 10.6GHz and a maximum oscillation frequency (fmax) of 6.9GHz. Nearly hysteresis-free Ids-Vgs characteristics and low flicker noise indicate that a high-quality SAND-GaAs interface is achieved.

  11. 碳纳米管/半导体纳米复合材料的光电化学特性及其应用%Photoelectrochemical Properties and Applications of Carbon Nanotubes/Semiconductor Nanocomposites

    Institute of Scientific and Technical Information of China (English)

    王娟; 刘颖; 张伟德

    2011-01-01

    Photoelectrochemieal process is an electrochemical process active research field currently. It is also the base of practical under light irradiation, which is a very applications for photovoltaic cells, photoelectrocatalysis and so on. The high performance photoelectrochemical devices are strongly dependent on advanced semiconductors or their nanocomposites with high quantum efficiency. On the other hand, because of their good chemical and thermal stability, high electrical conductivity and large surface area, carbon nanotubes (CNTs) have been used as effective supports for semiconductors, and their unique one-dimensional geometric structure provides effective transmission path for electrons. Moreover, carbon nanotube/semiconductor nanocomposites which have attracted great attentions usually exhibit synergistic effect for high photoeletrochemical response. The recombination of photo-induced electrons and holes will be restrained further with the applied bias voltage, thus facilitates the transfer of electrons to the external circuit. In this review paper, we summarize the progress of the recently published literatures and our findings on photoelectrochemical properties and applications based on carbon nanotubes/semiconductor nanocomposites. The enhancement mechanism for the high photoelectrochemical performance of the nanocomposites is discussed. The applications including solar ceils, photoelectrochemical degradation of pollutants and splitting of water for hydrogen generation are introduced in details. The prospect and challenge to the material science and future applications are also discussed.%光电化学过程是在光作用下的电化学过程,它是光伏电池,光电催化等实际应用的基础,是当前十分活跃的研究领域。碳纳米管具有很高的热稳定性,良好的导电能力,大的比表面积,被认为是半导体纳米粒子的有效载体,其独特的一维结构可以为电子提供有效的传输路径。碳纳

  12. Surface self-assembled hybrid nanocomposites with electroactive nanoparticles and enzymes confined in a polymer matrix for controlled electrocatalysis

    DEFF Research Database (Denmark)

    Zhu, Nan; Ulstrup, Jens; Chi, Qijin

    2015-01-01

    the microscopic structures of the different layers during the surface architecture formation. The resulting surface-bound nanostructured composite shows high electrochemical activity arising from confined PBNPs, and acts as an efficient electrocatalyst towards H2O2 reduction. Facile electron communication...... is achieved as reflected by a large electron transfer (ET) rate constant (ks) of 200 s-1, and the possible electron propagation mechanisms in the polymer network are discussed. This surface/interfacial nanocomposite can be further used in the accommodation of enzymes for electrochemical bio-catalysis. Glucose...

  13. Biomimetic hierarchical growth and self-assembly of hydroxyapatite/titania nanocomposite coatings and their biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Nathanael, A. Joseph, E-mail: ajosephnc@yahoo.com [Department of Nano, Medical and Polymer Materials, Yeungnam University, Gyeongsan (Korea, Republic of); Im, Young Min [Department of Nano, Medical and Polymer Materials, Yeungnam University, Gyeongsan (Korea, Republic of); Oh, Tae Hwan, E-mail: taehwanoh@ynu.ac.kr [Department of Nano, Medical and Polymer Materials, Yeungnam University, Gyeongsan (Korea, Republic of); Yuvakkumar, R. [Department of Nanomaterials Engineering, Chungnam National University, Daejeon (Korea, Republic of); Mangalaraj, D. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore (India)

    2015-03-30

    Graphical abstract: - Highlights: • Novel ‘bowtie’ like biomimetic HA/TiO{sub 2} nanocomposite coatings were prepared. • Simple sol–gel method was used to achieve this novel structure. • Details analysis confirms the formation of bowtie like structure in many ways. • Their functional analysis showed their enhanced activity for biomedical application. - Abstract: This article describes a systematic study of the biomimetic hierarchical growth of hydroxyapatite (HA)/titania (TiO{sub 2}) nanocomposite layered coatings applied by a simple sol–gel dip coating method. Highly stable HA and TiO{sub 2} sols were prepared prior to inducing biomimetic hierarchical growth. Initially, the samples formed a small leaf like structure; however, increasing the dipping cycle resulted in formation of an elongated seed-like structure. Increasing the number of dipping cycles further resulted in a ‘bowtie’ or straw-bale like nanowire structure with a length of 500 nm and a width of 100 nm. Each nanowire like structure had a width of very few nanometers. The crystalline structures, micro/nano structures and surface properties of the coatings were characterized by X-ray diffraction, scanning electron microscopy and atomic force microscopy respectively. In vitro cellular assays revealed that the growth of the cells in the ‘bowtie’ like structure improved over other samples.

  14. Biomimetic hierarchical growth and self-assembly of hydroxyapatite/titania nanocomposite coatings and their biomedical applications

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Novel ‘bowtie’ like biomimetic HA/TiO2 nanocomposite coatings were prepared. • Simple sol–gel method was used to achieve this novel structure. • Details analysis confirms the formation of bowtie like structure in many ways. • Their functional analysis showed their enhanced activity for biomedical application. - Abstract: This article describes a systematic study of the biomimetic hierarchical growth of hydroxyapatite (HA)/titania (TiO2) nanocomposite layered coatings applied by a simple sol–gel dip coating method. Highly stable HA and TiO2 sols were prepared prior to inducing biomimetic hierarchical growth. Initially, the samples formed a small leaf like structure; however, increasing the dipping cycle resulted in formation of an elongated seed-like structure. Increasing the number of dipping cycles further resulted in a ‘bowtie’ or straw-bale like nanowire structure with a length of 500 nm and a width of 100 nm. Each nanowire like structure had a width of very few nanometers. The crystalline structures, micro/nano structures and surface properties of the coatings were characterized by X-ray diffraction, scanning electron microscopy and atomic force microscopy respectively. In vitro cellular assays revealed that the growth of the cells in the ‘bowtie’ like structure improved over other samples

  15. Percolated conductive polyaniline-clay nanocomposite in polyvinyl chloride through the combined approach porous template and self-assembly

    Directory of Open Access Journals (Sweden)

    J. D. Sudha

    2014-02-01

    Full Text Available In this paper, we are reporting a novel strategy for the preparation of conductive polyaniline-clay nanocomposite in Polyvinylchloride (PVC matrix by admicellar emulsion polymerization using a low cost renewable resource based surfactant cum dopant. The highly oriented percolated network of polyaniline-clay nanocomposite in PVC matrix was revealed from the studies made by scanning electron microscopy (SEM and atomic force microscopy (AFM. Fourier transform infrared spectroscopy (FTIR results suggested that porous template was formed by the noncovalent interactions among the hydroxyl groups present in the nanoclay edges and the chloride ions present in PVC matrix. Here, the bio-based surfactant, 4-hydroxy-2-pentadecyl benzene-1-sulphonic acid (PDPSA performed multiple roles of dopant, emulsifier and soft template during the polymerization of anilinium+PDPSA– (An+PDPSA– in PVC-clay matrix. The prepared composite exhibited electrical conductivity (σdc of 4.8•10–2 S/cm and electromagnetic interference shielding efficiency (EMI SE of 55.2 dB suggesting it as a prospectable candidate for the encapsulation of electronic devices in high technological applications.

  16. Lecithin and PLGA-based self-assembled nanocomposite, Lecithmer: preparation, characterization, and pharmacokinetic/pharmacodynamic evaluation.

    Science.gov (United States)

    Varghese, Seby Elsy; Fariya, Mayur K; Rajawat, Gopal Singh; Steiniger, Frank; Fahr, Alfred; Nagarsenker, Mangal S

    2016-08-01

    The present study investigates the drug delivery potential of polymer lipid hybrid nanocomposites (Lecithmer®) composed of poly(D,L-lactide-co-glycolide (PLGA) and soya lecithin. Core-shell structure of Lecithmer was evident from cryo-TEM images. Daunorubicin (DNR) and lornoxicam (LNX)-incorporated Lecithmer nanocomposites were evaluated for anticancer and anti-inflammatory activity. DNR- and LNX-loaded Lecithmer had mean particle size of ∼335 and ∼282.7 nm, respectively. Lecithmer formulated with different cationic lipids resulted in lower particle size (∼120 nm) and positive zeta potential. Entrapment efficiency of DNR and LNX was 93.16 and 88.59 %, respectively. In vitro release of DNR from Lecithmer was slower compared to PLGA nanoparticles. DNR release from Lecithmer was significantly higher at pH 5.5 (80.96 %) as compared to pH 7.4 (55.95 %), providing advantage for selective tumor therapy. Similarly, sustained release of LNX (30 % in 10 h) was observed at pH 7.4. DNR in Lecithmer showed superior cytotoxicity on human erythroleukemic K562 cells. Pharmacokinetic study in Wistar rats with i.v. administered DNR-loaded Lecithmer showed higher volume of distribution, lower elimination rate constant, and longer half-life (81.68 L, 0.3535 h(-1), 1.96 h) as compared to DNR solution (57.46 L, 0.4237 h(-1), 1.635 h). Pharmacodynamic evaluation of orally administered LNX-loaded Lecithmer showed superior anti-inflammatory activity with maximum inhibition of 81.2 % vis-à-vis 53.57 % in case of LNX suspension. In light of these results, Lecithmer can be envisaged as a promising nanosystem for parenteral as well as oral drug delivery. PMID:27371394

  17. Lecithin and PLGA-based self-assembled nanocomposite, Lecithmer: preparation, characterization, and pharmacokinetic/pharmacodynamic evaluation.

    Science.gov (United States)

    Varghese, Seby Elsy; Fariya, Mayur K; Rajawat, Gopal Singh; Steiniger, Frank; Fahr, Alfred; Nagarsenker, Mangal S

    2016-08-01

    The present study investigates the drug delivery potential of polymer lipid hybrid nanocomposites (Lecithmer®) composed of poly(D,L-lactide-co-glycolide (PLGA) and soya lecithin. Core-shell structure of Lecithmer was evident from cryo-TEM images. Daunorubicin (DNR) and lornoxicam (LNX)-incorporated Lecithmer nanocomposites were evaluated for anticancer and anti-inflammatory activity. DNR- and LNX-loaded Lecithmer had mean particle size of ∼335 and ∼282.7 nm, respectively. Lecithmer formulated with different cationic lipids resulted in lower particle size (∼120 nm) and positive zeta potential. Entrapment efficiency of DNR and LNX was 93.16 and 88.59 %, respectively. In vitro release of DNR from Lecithmer was slower compared to PLGA nanoparticles. DNR release from Lecithmer was significantly higher at pH 5.5 (80.96 %) as compared to pH 7.4 (55.95 %), providing advantage for selective tumor therapy. Similarly, sustained release of LNX (30 % in 10 h) was observed at pH 7.4. DNR in Lecithmer showed superior cytotoxicity on human erythroleukemic K562 cells. Pharmacokinetic study in Wistar rats with i.v. administered DNR-loaded Lecithmer showed higher volume of distribution, lower elimination rate constant, and longer half-life (81.68 L, 0.3535 h(-1), 1.96 h) as compared to DNR solution (57.46 L, 0.4237 h(-1), 1.635 h). Pharmacodynamic evaluation of orally administered LNX-loaded Lecithmer showed superior anti-inflammatory activity with maximum inhibition of 81.2 % vis-à-vis 53.57 % in case of LNX suspension. In light of these results, Lecithmer can be envisaged as a promising nanosystem for parenteral as well as oral drug delivery.

  18. Self-assembly modified-mushroom nanocomposite for rapid removal of hexavalent chromium from aqueous solution with bubbling fluidized bed

    OpenAIRE

    Fei Xu; Xu Liu; Yijiao Chen; Ke Zhang; Heng Xu

    2016-01-01

    A self-assembled modified Pleurotus Cornucopiae material (SMPM) combined with improved Intermittent Bubbling Fluidized Bed (IBFB) was investigated to remove the hexavalent chromium ions in aqueous solution. After the modification, the powder-like raw material gradually self-assembled together to SMPM, which had crinkly porous structure, improved the Cr-accommodation ability in a sound manner. Optimized by Taguchi method, Cr(VI) removal efficiency was up to 75.91% and 48.01% for 100 mg/L and 5...

  19. Chemically specific multiscale modeling of clay-polymer nanocomposites reveals intercalation dynamics, tactoid self-assembly and emergent materials properties.

    Science.gov (United States)

    Suter, James L; Groen, Derek; Coveney, Peter V

    2015-02-01

    A quantitative description is presented of the dynamical process of polymer intercalation into clay tactoids and the ensuing aggregation of polymer-entangled tactoids into larger structures, obtaining various characteristics of these nanocomposites, including clay-layer spacings, out-of-plane clay-sheet bending energies, X-ray diffractograms, and materials properties. This model of clay-polymer interactions is based on a three-level approach, which uses quantum mechanical and atomistic descriptions to derive a coarse-grained yet chemically specific representation that can resolve processes on hitherto inaccessible length and time scales. The approach is applied to study collections of clay mineral tactoids interacting with two synthetic polymers, poly(ethylene glycol) and poly(vinyl alcohol). The controlled behavior of layered materials in a polymer matrix is centrally important for many engineering and manufacturing applications. This approach opens up a route to computing the properties of complex soft materials based on knowledge of their chemical composition, molecular structure, and processing conditions. PMID:25488829

  20. Inorganic/organic small molecular semiconductor self-assembly to functional core-shell nanoarchitectures for ultrasensitive chemiresistors to aniline vapor.

    Science.gov (United States)

    Wang, Ke; Yang, Hui; Qian, Xuemin; Xue, Zheng; Li, Yongjun; Liu, Huibiao; Li, Yuliang

    2014-08-14

    We developed a new method combining the in situ liquid-solid phase reaction and self-assembly in solution to synthesize novel inorganic/organic small molecular semiconductor core-shell nanoparticles of ZnS/PTCDA (ZPNPs). This method is a one-step process which can produce stoichiometric inorganic/organic core-shell nanoparticles and does not introduce any impurity. The film of ZPNPs exhibited an ultrasensitive detection of aniline vapor. The film of ZPNPs can highly selectively distinguish aniline vapor from many volatile organic compounds and water due to the strong synergistic interactions of π-π and hydrogen-bonds between electron donor (aniline) and acceptor (PTCDA) molecules, in which the detection limit was lowered to 100 ppb at room temperature. PMID:24915438

  1. Self-assembly modified-mushroom nanocomposite for rapid removal of hexavalent chromium from aqueous solution with bubbling fluidized bed

    Science.gov (United States)

    Xu, Fei; Liu, Xu; Chen, Yijiao; Zhang, Ke; Xu, Heng

    2016-05-01

    A self-assembled modified Pleurotus Cornucopiae material (SMPM) combined with improved Intermittent Bubbling Fluidized Bed (IBFB) was investigated to remove the hexavalent chromium ions in aqueous solution. After the modification, the powder-like raw material gradually self-assembled together to SMPM, which had crinkly porous structure, improved the Cr-accommodation ability in a sound manner. Optimized by Taguchi method, Cr(VI) removal efficiency was up to 75.91% and 48.01% for 100 mg/L and 500 mg/L initial concentration of Cr(VI), respectively. Results indicated that the metal removal was dependent on dosage of adsorbent, particle diameter and treatment time. The experimental data obtained from the biosorption process was successfully correlated with Freundlich isotherm model. Thermodynamic study indicated the endothermic nature of the process. The results confirmed that self-assembly modified Pleurotus Cornucopiae material could be applied for the removal of heavy metal from wastewater in continuous fluidized bed process.

  2. Biocatalytic self-assembly of supramolecular charge-transfer nanostructures based on n-type semiconductor-appended peptides.

    Science.gov (United States)

    Nalluri, Siva Krishna Mohan; Berdugo, Cristina; Javid, Nadeem; Frederix, Pim W J M; Ulijn, Rein V

    2014-06-01

    The reversible in situ formation of a self-assembly building block (naphthalenediimide (NDI)-dipeptide conjugate) by enzymatic condensation of NDI-functionalized tyrosine (NDI-Y) and phenylalanine-amide (F-NH2) to form NDI-YF-NH2 is described. This coupled biocatalytic condensation/assembly approach is thermodynamically driven and gives rise to nanostructures with optimized supramolecular interactions as evidenced by substantial aggregation induced emission upon assembly. Furthermore, in the presence of di-hydroxy/alkoxy naphthalene donors, efficient charge-transfer complexes are produced. The dynamic formation of NDI-YF-NH2 and electronic and H-bonding interactions are analyzed and characterized by different methods. Microscopy (TEM and AFM) and rheology are used to characterize the formed nanostructures. Dynamic nanostructures, whose formation and function are driven by free-energy minimization, are inherently self-healing and provide opportunities for the development of aqueous adaptive nanotechnology. PMID:24788665

  3. Preparation and characterization of self-assembled layer by layer NiCo{sub 2}O{sub 4}–reduced graphene oxide nanocomposite with improved electrocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Manish; Elias Uddin, Md. [Advanced Materials Research Institute for BIN Fusion Technology (BK Plus Global Program), Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Singh, Jay [Department of Applied Chemistry, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Kim, Nam Hoon [Advanced Materials Research Institute for BIN Fusion Technology (BK Plus Global Program), Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Lee, Joong Hee, E-mail: jhl@chonbuk.ac.kr [Advanced Materials Research Institute for BIN Fusion Technology (BK Plus Global Program), Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Advanced Wind Power System Research Center, Department of Polymer and Nano Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

    2014-03-25

    Graphical abstract: NiCo{sub 2}O{sub 4} were grown on RGO by in situ synthesis process. FE-SEM investigation revealed self assembled layer by layer growth of NiCo{sub 2}O{sub 4}–RGO nanocomposite. NiCo{sub 2}O{sub 4}–RGO nanocomposite exhibited synergetic effect of NiCo{sub 2}O{sub 4} nanoparticles and RGO on its electrochemical performance. -- Highlights: • NiCo{sub 2}O{sub 4} were grown on RGO by in-situ synthesis process. • FE-SEM image revealed self-assembled layer by layer growth of NiCo{sub 2}O{sub 4}-RGO nanocomposite. • NiCo{sub 2}O{sub 4}-RGO nanocomposite exhibited synergetic effects on its electrochemical performance. -- Abstract: NiCo{sub 2}O{sub 4} nanoparticles dispersed on reduced graphene oxide (RGO) are prepared by simultaneously reducing graphene oxide (GO), nickel and cobalt nitrate via a hydrothermal method assisted by post annealing at low temperature. The method involves formation of hydroxides on GO using ammonia under hydrothermal conditions. Subsequent thermal treatment at 300 °C led to the conversion of hydroxides into single-phase NiCo{sub 2}O{sub 4} atop the RGO. The synthesized products are characterized through several techniques including X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The FE-SEM investigations reveal the growth of a layer by layer assembly of NiCo{sub 2}O{sub 4}–RGO (2:1) nanocomposite, where the NiCo{sub 2}O{sub 4} nanoparticles are tightly packed between the layers of RGO. Further, the catalytic properties of the NiCo{sub 2}O{sub 4}–RGO nanocomposite are investigated for the oxygen evolution reaction (OER) through cyclic voltammetry (CV) measurements. It is observed that the special structural features of the NiCo{sub 2}O{sub 4}–RGO (2:1) nanocomposite, including

  4. Interpretation of dc and ac conductivity of Ag{sub 2}O–SeO{sub 2}–MoO{sub 3} glass-nanocomposite-semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Sanjib, E-mail: sanjib_ssp@yahoo.co.in [Department of Engineering Sciences and Humanities, Siliguri Institute of Technology, Darjeeeling 734009, West Bengal (India); Kundu, Ranadip [Department of Engineering Sciences and Humanities, Siliguri Institute of Technology, Darjeeeling 734009, West Bengal (India); Department of Mechanical Engineering, Jadavpur University, Jadavpur, Kolkata 700032 (India); Das, Anindya Sundar [Department of Mechanical Engineering, Jadavpur University, Jadavpur, Kolkata 700032 (India); Department of Electronics and Communication Engineering, Regent Education and Research Foundation, Barrackpore, Kolkata 7000121 (India); Roy, Debasish [Department of Mechanical Engineering, Jadavpur University, Jadavpur, Kolkata 700032 (India)

    2015-07-15

    Highlights: • Polaron hopping. • Dc and ac conductivity. • Mott's model and Greave's model. • Ag{sub 2}MoO{sub 4}, Ag{sub 2}Mo{sub 2}O{sub 7} and Ag{sub 6}Mo{sub 10}O{sub 33} nanoparticles and SeO{sub 3} and SeO{sub 4} nanoclusters. • XRD and FESEM studies. - Abstract: A new type of semiconducting glass-nanocomposites 0.3Ag{sub 2}O–0.7 (xMoO{sub 3}–(1 − x) SeO{sub 2}) is prepared by melt-quenching route. The formation of Ag{sub 2}MoO{sub 4}, Ag{sub 2}Mo{sub 2}O{sub 7} and Ag{sub 6}Mo{sub 10}O{sub 33} nanoparticles and SeO{sub 3} and SeO{sub 4} nanoclusters in glass-nanocomposites has been confirmed from X-ray diffraction (XRD) and field emission scanning electron microscopic (FESEM) studies. Fourier transform infrared (FTIR) spectroscopy is employed to find out Se−O stretching vibration as well as stretching vibrations of Mo{sub 2}O{sub 7}{sup 2−} ions. The dc conductivity of them is studied on the light of polaron hopping approach in a wide temperature range. At low temperatures, variable range hopping model (Mott's model) is employed to analyze the conductivity data. Greave's model is used to predict temperature dependent variable range hopping in the high temperature region. Frequency dependent ac conductivity is well explained on the basis of tunneling. I–V characteristics of the as-prepared samples have also been investigated.

  5. Synthesis of uniform CdS nanospheres/graphene hybrid nanocomposites and their application as visible light photocatalyst for selective reduction of nitro organics in water.

    Science.gov (United States)

    Chen, Zhang; Liu, Siqi; Yang, Min-Quan; Xu, Yi-Jun

    2013-05-22

    We report the self-assembly of uniform CdS nanospheres/graphene (CdS NSPs/GR) hybrid nanocomposites via electrostatic interaction of positively charged CdS nanospheres (CdS NSPs) with negatively charged graphene oxide (GO), followed by GO reduction via a hydrothermal treatment. During this facile two-step wet chemistry process, reduced graphene oxide (RGO, also called GR) and the intimate interfacial contact between CdS NSPs and the GR sheets are achieved. Importantly, the CdS NSPs/GR nanocomposites exhibit a much higher photocatalytic performance than bare CdS NSPs toward selective reduction of nitro organics to corresponding amino organics under visible light irradiation. The superior photocatalytic performance of the CdS NSPs/GR nanocomposites can be attributed to the intimate interfacial contact between CdS NSPs and the GR sheets, which would maximize the excellent electron conductivity and mobility of GR that in turn markedly contributes to improving the fate and transfer of photogenerated charge carriers from CdS NSPs under visible light irradiation. Moreover, the photocorrosion of CdS and the photodegradation of GR can be efficiently inhibited. The excellent reusability of the CdS NSPs/GR nanocomposites can be attributed to the synergetic effect of the introduction of GR into the matrix of CdS NSPs and the addition of ammonium formate as quencher for photogenerated holes. It is hoped that our current work could promote us to efficiently harness such a simple and efficient self-assembly strategy to synthesize GR-based semiconductor composites with controlled morphology and, more significantly, widen the application of CdS/GR nanocomposite photocatalysts and offer new inroads into exploration and utilization of GR-based semiconductor nanocomposites as visible light photocatalysts for selective organic transformations.

  6. Synthesis and applications of heterostructured semiconductor nanocrystals

    Science.gov (United States)

    Khon, Elena

    Semiconductor nanocrystals (NCs) have been of great interest to researchers for several decades due to their unique optoelectronic properties. These nanoparticles are widely used for a variety of different applications. However, there are many unresolved issues that lower the efficiency and/or stability of devices which incorporate these NCs. Our research is dedicated to addressing these issues by identifying potential problems and resolving them, improving existing systems, generating new synthetic strategies, and/or building new devices. The general strategies for the synthesis of different nanocrystals were established in this work, one of which is the colloidal growth of gold domains onto CdS semiconductor nanocrystals. Control of shape and size was achieved simply by adjusting the temperature and the time of the reaction. Depending on the exact morphology of Au and CdS domains, fabricated nano-composites can undergo evaporation-induced self-assembly onto a substrate, which is very useful for building devices. CdS/Au heterostructures can assemble in two different ways: through end-to-end coupling of Au domains, resulting in the formation of one-dimensional chains; and via side-by-side packing of CdS nanorods, leading to the onset of two-dimensional superlattices. We investigated the nature of exciton-plasmon interactions in Au-tipped CdS nanorods using femtosecond transient absorption spectroscopy. The study demonstrated that the key optoelectronic properties of electrically coupled metal and semiconductor domains are significantly different from those observed in systems with weak inter-domain coupling. In particular, strongly-coupled nanocomposites promote mixing of electronic states at semiconductor-metal domain interfaces, which causes a significant suppression of both plasmon and exciton carrier excitations. Colloidal QDs are starting to replace organic molecules in many different applications, such as organic light emmiting diods (OLEDs), due to their

  7. Polyolefin nanocomposites

    Science.gov (United States)

    Chaiko, David J.

    2007-01-02

    The present invention relates to methods for the preparation of clay/polymer nanocomposites. The methods include combining an organophilic clay and a polymer to form a nanocomposite, wherein the organophilic clay and the polymer each have a peak recrystallization temperature, and wherein the organophilic clay peak recrystallization temperature sufficiently matches the polymer peak recrystallization temperature such that the nanocomposite formed has less permeability to a gas than the polymer. Such nanocomposites exhibit 2, 5, 10, or even 100 fold or greater reductions in permeability to, e.g., oxygen, carbon dioxide, or both compared to the polymer. The invention also provides a method of preparing a nanocomposite that includes combining an amorphous organophilic clay and an amorphous polymer, each having a glass transition temperature, wherein the organophilic clay glass transition temperature sufficiently matches the polymer glass transition temperature such that the nanocomposite formed has less permeability to a gas than the polymer.

  8. Semiconductor packaging materials interaction and reliability

    CERN Document Server

    Chen, Andrea

    2012-01-01

    In semiconductor manufacturing, understanding how various materials behave and interact is critical to making a reliable and robust semiconductor package. Semiconductor Packaging: Materials Interaction and Reliability provides a fundamental understanding of the underlying physical properties of the materials used in a semiconductor package. The book focuses on an important step in semiconductor manufacturing--package assembly and testing. It covers the basics of material properties and explains how to determine which behaviors are important to package performance. The authors also discuss how

  9. Self-assembled hybrid materials based on conjugated polymers and semiconductors nano-crystals for plastic solar cells

    International Nuclear Information System (INIS)

    This work is devoted to the elaboration of self-assembled hybrid materials based on poly(3- hexyl-thiophene) and CdSe nano-crystals for photovoltaic applications. For that, complementary molecular recognition units were introduced as side chain groups on the polymer and at the nano-crystals' surface. Diamino-pyrimidine groups were introduced by post-functionalization of a precursor copolymer, namely poly(3-hexyl-thiophene-co-3- bromo-hexyl-thiophene) whereas thymine groups were introduced at the nano-crystals' surface by a ligand exchange reaction with 1-(6-mercapto-hexyl)thymine. However, due to their different solubility, the mixing of the two components by solution processes is difficult. A 'one-pot' procedure was developed, but this method led to insoluble aggregates without control of the hybrid composition. To overcome the solubility problem, the layer-by-layer method was used to prepare the films. This method allows a precise control of the deposition process. Experimental parameters were tested in order to evaluate their impact on the resulting film. The films morphology was investigated by microscopy and X-Ray diffraction techniques. These analyses reveal an interpenetrated structure of nano-crystals within the polymer matrix rather than a multilayered structure. Electrochemical and spectro electrochemical studies were performed on the hybrid material deposited by the LBL process. Finally the materials were tested in a solar cell configuration and the I=f(V) curves reveals a clear photovoltaic behaviour. (author)

  10. High-performance thermoelectric nanocomposites from nanocrystal building blocks.

    Science.gov (United States)

    Ibáñez, Maria; Luo, Zhishan; Genç, Aziz; Piveteau, Laura; Ortega, Silvia; Cadavid, Doris; Dobrozhan, Oleksandr; Liu, Yu; Nachtegaal, Maarten; Zebarjadi, Mona; Arbiol, Jordi; Kovalenko, Maksym V; Cabot, Andreu

    2016-01-01

    The efficient conversion between thermal and electrical energy by means of durable, silent and scalable solid-state thermoelectric devices has been a long standing goal. While nanocrystalline materials have already led to substantially higher thermoelectric efficiencies, further improvements are expected to arise from precise chemical engineering of nanoscale building blocks and interfaces. Here we present a simple and versatile bottom-up strategy based on the assembly of colloidal nanocrystals to produce consolidated yet nanostructured thermoelectric materials. In the case study on the PbS-Ag system, Ag nanodomains not only contribute to block phonon propagation, but also provide electrons to the PbS host semiconductor and reduce the PbS intergrain energy barriers for charge transport. Thus, PbS-Ag nanocomposites exhibit reduced thermal conductivities and higher charge carrier concentrations and mobilities than PbS nanomaterial. Such improvements of the material transport properties provide thermoelectric figures of merit up to 1.7 at 850 K.

  11. Green self-assembly of zein-conjugated ZnO/Cd(OH)Cl hierarchical nanocomposites with high cytotoxicity and immune organs targeting

    Science.gov (United States)

    Wang, Hua-Jie; Cao, Ying; Wang, Cai-Feng; Cui, Shi-Zhong; Mi, Li-Wei; Miyazawa, Teruo

    2016-04-01

    Inorganic nanomedicines in the fight against cancer have progressed rapidly during recent years, with the synergistic advantages of multifunctional nanosystems compared to single component. Herein, a drug-combination opinion was introduced into “nanomedicine” based on the understanding of Trojan horse-anti-tumor mechanism of inorganic nano-medicines. Moreover, we reported the green and facile synthesis route of mono-dispersed and rod-like zein-conjugated ZnO/Cd(OH)Cl hierarchical nanocomposites. We found that the nanocomposites exhibited high-efficiency killing ability to tumor cells through lipid peroxidation mediated-membrane disintegration route. The safety studies in BALB/c mice didn’t detect injection anaphylaxis, hemolysis and cytotoxicity. More interestingly, the nano-composites could specially accumulate in liver and kidney, which will be helpful for targeting cure to these regional cancers.

  12. Hybrid Thin Films Based Upon Polyoxometalates-Polymer Assembly

    Science.gov (United States)

    Qi, Na; Jing, Benxin; Zhu, Yingxi

    2014-03-01

    Block copolymers (BCPs) and polyoxometalates (POMs) have been used individually as building blocks for design and synthesis of novel functional materials. POM nanoclusters, the assemblies of transition metal oxides with well-defined atomic coordination structure, have been recently explored as novel nanomaterials... for catalysis, semiconductors, and even anti-cancer treatment due to their unique chemical, optical and electrical characteristics. We have explored the blending of inorganic POM nanocluster with BCPs into hierarchaically structured inorganic-organic hybrid nanocomposites. Using polystyrene-b-poly(ethylene oxide) (PS-b-PEO) thin films as the template, we have observed that the spatial organization of BCP thin films is modified by molybdenum based POM nanocluster to form 2D in-plane hexagonal ordered or 3D ordered network of POM-BCP assemblies, depending on the concentration ratio of POM to PS-b-PEO. The dielectric properties of such hybrid thin films can be enhanced by embedded POMs but show a strong dependence on the supramolecular structures of POM-polymer complexes. The assembly of nanoclusters in BCP-templated thin films could pave a new path to design new hybrid nanocomposites with uniquely combined functionality and material properties.

  13. Highly Conductive Multifunctional Graphene Polycarbonate Nanocomposites

    Science.gov (United States)

    Yoonessi, Mitra; Gaier, James R.

    2010-01-01

    Graphene nanosheet bisphenol A polycarbonate nanocomposites (0.027 2.2 vol %) prepared by both emulsion mixing and solution blending methods, followed by compression molding at 287 C, exhibited dc electrical percolation threshold of approx.0.14 and approx.0.38 vol %, respectively. The conductivities of 2.2 vol % graphene nanocomposites were 0.512 and 0.226 S/cm for emulsion and solution mixing. The 1.1 and 2.2 vol % graphene nanocomposites exhibited frequency-independent behavior. Inherent conductivity, extremely high aspect ratio, and nanostructure directed assembly of the graphene using PC nanospheres are the main factors for excellent electrical properties of the nanocomposites. Dynamic tensile moduli of nanocomposites increased with increasing graphene in the nanocomposite. The glass transition temperatures were decreased with increasing graphene for the emulsion series. High-resolution electron microscopy (HR-TEM) and small-angle neutron scattering (SANS) showed isolated graphene with no connectivity path for insulating nanocomposites and connected nanoparticles for the conductive nanocomposites. A stacked disk model was used to obtain the average particle radius, average number of graphene layers per stack, and stack spacing by simulation of the experimental SANS data. Morphology studies indicated the presence of well-dispersed graphene and small graphene stacking with infusion of polycarbonate within the stacks.

  14. Graphene-based artificial nacre nanocomposites.

    Science.gov (United States)

    Zhang, Yuanyuan; Gong, Shanshan; Zhang, Qi; Ming, Peng; Wan, Sijie; Peng, Jingsong; Jiang, Lei; Cheng, Qunfeng

    2016-05-01

    With its extraordinary properties as the strongest and stiffest material ever measured and the best-known electrical conductor, graphene could have promising applications in many fields, especially in the area of nanocomposites. However, processing graphene-based nanocomposites is very difficult. So far, graphene-based nanocomposites exhibit rather poor properties. Nacre, the gold standard for biomimicry, provides an excellent example and guidelines for assembling two-dimensional nanosheets into high performance nanocomposites. The inspiration from nacre overcomes the bottleneck of traditional approaches for constructing nanocomposites, such as poor dispersion, low loading, and weak interface interactions. This tutorial review summarizes recent research on graphene-based artificial nacre nanocomposites and focuses on the design of interface interactions and synergistic effects for constructing high performance nanocomposites. This tutorial review also focuses on a perspective of the dynamic area of graphene-based nanocomposites, commenting on whether the concept is viable and practical, on what has been achieved to date, and most importantly, what is likely to be achieved in the future. PMID:27039951

  15. Nanocomposite for radiation detection

    Science.gov (United States)

    Sahi, Sunil

    2012-02-01

    Cerium fluoride is among the widely studied inorganic scintillators for radiation detection, because of its high light output and high stopping power. Herein, platelets shape CeF3 nanoparticles for radiation detection was synthesis by bisolvent solvothermal method. The characterization of nanoprticles was done by photoluminescence, XRD and SEM measurement. The synthesized CeF3 nanoparticles have broad emission peak around 330 nm. ZnO is a semiconductor scintillator, having fast decay time. ZnO nanoparticles were synthesized using solvothermal method and UV-Vis, photoluminescence and SEM measurement were done for their characterization. The absorption spectrum of the ZnO nanoparticles is dependent on the size of the nanoparticles. By changing the temperature and the concentration of zinc salt and surfactant, ZnO with absorption spectra overlapping with the emission spectra of CeF3 were made for the purpose of creating nanocomposites, with improved scintillation properties. The energy transfer between two nanoparticles was also studied and the changes in Photoluminescence intensity of the nanocomposites were described.

  16. Colloidal QDs-polymer nanocomposites

    Science.gov (United States)

    Gordillo, H.; Suárez, I.; Rodríguez-Cantó, P.; Abargues, R.; García-Calzada, R.; Chyrvony, V.; Albert, S.; Martínez-Pastor, J.

    2012-04-01

    Nanometer-size colloidal semiconductor nanocrystals, or Quantum Dots (NQD), are very prospective active centers because their light emission is highly efficient and temperature-independent. Nanocomposites based on the incorporation of QDs inside a polymer matrix are very promising materials for application in future photonic devices because they combine the properties of QDs with the technological feasibility of polymers. In the present work some basic applications of these new materials have been studied. Firstly, the fabrication of planar and linear waveguides based on the incorporation of CdS, CdSe and CdTe in PMMA and SU-8 are demonstrated. As a result, photoluminescence (PL) of the QDs are coupled to a waveguide mode, being it able to obtain multicolor waveguiding. Secondly, nanocomposite films have been evaluated as photon energy down-shifting converters to improve the efficiency of solar cells.

  17. Metal Nanocomposites

    DEFF Research Database (Denmark)

    Fischer, Søren Vang; Uthuppu, Basil; Jakobsen, Mogens Havsteen

    2014-01-01

    We have made SU-8 gold nanoparticle composites in two ways, ex situ and in situ, and found that in both methods nanoparticles embedded in the polymer retained their plasmonic properties. The in situ method has also been used to fabricate a silver nanocomposite which is electrically conductive...

  18. Low TCR nanocomposite strain gages

    Science.gov (United States)

    Gregory, Otto J. (Inventor); Chen, Ximing (Inventor)

    2012-01-01

    A high temperature thin film strain gage sensor capable of functioning at temperatures above 1400.degree. C. The sensor contains a substrate, a nanocomposite film comprised of an indium tin oxide alloy, zinc oxide doped with alumina or other oxide semiconductor and a refractory metal selected from the group consisting of Pt, Pd, Rh, Ni, W, Ir, NiCrAlY and NiCoCrAlY deposited onto the substrate to form an active strain element. The strain element being responsive to an applied force.

  19. Cu and CuO/titanate nanobelt based network assemblies for enhanced visible light photocatalysis.

    Science.gov (United States)

    Logar, Manca; Bračko, Ines; Potočnik, Anton; Jančar, Boštjan

    2014-04-29

    3D network configurations of copper(II) oxide/titanate nanobelt (CuO/TiNBs) and copper/titanate nanobelt (Cu/TiNBs) were formed using a two-step polyelectrolyte-assisted synthesis and assembly approach. The photoactivity of the TiNB/CuO and Cu/TiNB composite networks is significantly enhanced as compared to the activity of 3D structures formed of pristine TiNB. An efficient, UV-vis-light-induced electron transfer at the two-component interface achieved by the intimate coupling of TiNB with p-type semiconducting CuO and plasmonic Cu nanoparticles in composite heterostructures facilitates control over the system's exciton dynamics, which results in highly efficient UV-vis photocatalytic performance of heterostructures. The superior photocatalytic activity of the metal and semiconductor/semiconductor nanocomposite structures in the visible region is discussed, highlighting the role of interfacial electron-charge transfer (IFCT) in semiconductor-semiconductor (CuO/TiNB) and surface plasmon resonance (SPR) of Cu nanoparticles in metal-semiconductor heterostructures. PMID:24697758

  20. Charge carrier transport at the nanoscale: Electron and hole transport in self-assembled discotic liquid crystals: Mobile ionic charges in nanocomposite solid electrolytes

    NARCIS (Netherlands)

    Haverkate, L.A.

    2013-01-01

    This thesis explores some fundamental aspects of charge carrier transport at the nanoscale. The study is divided in two parts. In the first part, the structural, dynamical and vibrational properties of discotic liquid crystals are studied in relation to the potential of these self-assembled ‘mesopha

  1. Microstructure and superconducting properties of YBa2Cu3O7−δ thin films incorporated with a self-assembled magnetic vertically aligned nanocomposite

    International Nuclear Information System (INIS)

    A thin layer of a vertically aligned nanocomposite (VAN) with separated phases of ferromagnetic Fe2O3 and non-magnetic CeO2, arranged as alternating nanopillars, is introduced in YBa2Cu3O7−δ (YBCO) thin films as either a cap or a buffer layer using a pulsed laser deposition method. Detailed microstructural characterization including XRD, high resolution XTEM and STEM is conducted and correlated with the superconducting properties to investigate the flux pinning properties introduced by the magnetic VAN layers. The Tc values of both doped samples are above 89 K and the Jcsf measured at 65 K increased to 150% of that of the reference YBCO prepared under the same conditions. As the measurement temperature decreases, the magnetic pinning effect increases and the field dependent Jc(H ∥ c) is further improved to more than 200% of the Jc value of the reference YBCO sample. This suggests that the Fe2O3:CeO2 VAN can provide both ordered magnetic pillars and controlled defect density. Furthermore, the magnetic pillars are very effective pinning centers especially in the high field and low temperature regime. (paper)

  2. Stretchable semiconductor elements and stretchable electrical circuits

    Science.gov (United States)

    Rogers, John A.; Khang, Dahl-Young; Menard, Etienne

    2009-07-07

    The invention provides methods and devices for fabricating printable semiconductor elements and assembling printable semiconductor elements onto substrate surfaces. Methods, devices and device components of the present invention are capable of generating a wide range of flexible electronic and optoelectronic devices and arrays of devices on substrates comprising polymeric materials. The present invention also provides stretchable semiconductor structures and stretchable electronic devices capable of good performance in stretched configurations.

  3. Semiconductor spintronics

    CERN Document Server

    Xia, Jianbai; Chang, Kai

    2012-01-01

    Semiconductor Spintronics, as an emerging research discipline and an important advanced field in physics, has developed quickly and obtained fruitful results in recent decades. This volume is the first monograph summarizing the physical foundation and the experimental results obtained in this field. With the culmination of the authors' extensive working experiences, this book presents the developing history of semiconductor spintronics, its basic concepts and theories, experimental results, and the prospected future development. This unique book intends to provide a systematic and modern foundation for semiconductor spintronics aimed at researchers, professors, post-doctorates, and graduate students, and to help them master the overall knowledge of spintronics.

  4. Semiconductor heterojunctions

    CERN Document Server

    Sharma, B L

    1974-01-01

    Semiconductor Heterojunctions investigates various aspects of semiconductor heterojunctions. Topics covered include the theory of heterojunctions and their energy band profiles, electrical and optoelectronic properties, and methods of preparation. A number of heterojunction devices are also considered, from photovoltaic converters to photodiodes, transistors, and injection lasers.Comprised of eight chapters, this volume begins with an overview of the theory of heterojunctions and a discussion on abrupt isotype and anisotype heterojunctions, along with graded heterojunctions. The reader is then

  5. Highly efficient removal of Malachite green from water by a magnetic reduced graphene oxide/zeolitic imidazolate framework self-assembled nanocomposite

    Science.gov (United States)

    Lin, Kun-Yi Andrew; Lee, Wei-Der

    2016-01-01

    Compared to the relatively low adsorption capacities of conventional adsorbents for Malachite Green (MG) (i.e., ∼500 mg g-1), zeolitic imidazolate framework (ZIF) appears to be a promising adsorbent considering its significantly high adsorption capacity (i.e., >2000 mg g-1). Nevertheless, using such a nano-scale ZIF material for adsorption may lead to secondary contamination from the release of nanomaterials to the environment. Thus, ZIF has to be recovered conveniently to prevent the secondary contamination and facilitate the separation of adsorbent from water after adsorption. To this end, in this study ZIF nanocrystals were loaded on the sheet-like magnetic reduced graphene oxide (MRGO) to form a self-assembled MRGO/ZIF. The self-assembly of MRGO/ZIF was achieved possibly via the electrostatic attraction and the π-π stacking interaction between MRGO and ZIF. The resultant MRGO/ZIF exhibited an ultra-high adsorption capacity for MG (∼3000 mg g-1). The adsorption kinetics, isotherm, activation and thermodynamics were also determined. Other factors affecting the adsorption were examined including temperature, pH and co-existing ions/compound. To demonstrate that MRGO/ZIF can be recovered and reused, a multiple-cycle of MG adsorption using the regenerated MRGO/ZIF was revealed and the recyclability remained highly efficient and stable. The highly-effective, recoverable and re-usable features enable MRGO/ZIF a promising adsorbent to remove MG from water.

  6. Synthesis and characterisation: Zinc oxide-sulfide nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Prinsa, E-mail: prinsa.verma@gmail.co [Nanophosphor Application Center, Allahabad University (India); Satish Dhawan Space Center, ISRO (India); Pandey, Avinash C. [Nanophosphor Application Center, Allahabad University (India); Bhargava, R.N. [Nanocrystal Technology, New York (United States)

    2009-11-15

    A novel synthesis method is presented for the preparation of nanosized-semiconductor zinc oxide-sulphide (ZnO/ZnS) core-shell nanocomposites, both formed sequentially from a single-source solid precursor. ZnO nanocrystals were synthesized by a simple co-precipitation method and ZnO/ZnS core-shell nanocomposites were successfully fabricated by sulfidation of ZnO nanocrystals via a facile chemical synthesis at room temperature. The as-obtained samples were characterized by X-ray diffraction and transmission electron microscopy. The results showed that the pure ZnO nanocrystals were hexagonal wurtzite crystal structures and the ZnS nanoparticles were sphalerite structure with the size of about 10 nm grown on the surface of the ZnO nanocrystals. Optical properties measured reveal that ZnO/ZnS core-shell nanocomposites have integrated the photoluminescent effect of ZnO and ZnS. Based on the results of the experiments, a possible formation mechanism of ZnO/ZnS core-shell nanocomposites was also suggested. This treatment is suggested to improve various properties of optoelectronically valuable ZnO/ZnS nanocomposites. These nanosized semiconductor nanocomposites can form a new class of luminescent materials for various applications.

  7. Design Wood Nanocomposites from Polymer Nanocomposites

    Institute of Scientific and Technical Information of China (English)

    LVWenhua; ZHAOGuangjie

    2004-01-01

    Researches on wood nanocomposites, which involve nano science and technology, wood science,materials science and other related subjects, have important science signification and promising prospect for the development and study of new wood composites with high appending values and multi-properties. This paper reviewed the conventional wood composites, and then discussed the approaches to prepare wood nanocomposites. Based on the achievements of researches on polymer/montmorillonite (MMT) nanocomposites, the design ideas of preparing nanocomposites of wood and inorganic MMT were systematically put forward. Nano compounding of wood and other materials is an effective approach to greatly improve or modify wood.

  8. Oxide semiconductors

    CERN Document Server

    Svensson, Bengt G; Jagadish, Chennupati

    2013-01-01

    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scient

  9. Semiconductor statistics

    CERN Document Server

    Blakemore, J S

    1962-01-01

    Semiconductor Statistics presents statistics aimed at complementing existing books on the relationships between carrier densities and transport effects. The book is divided into two parts. Part I provides introductory material on the electron theory of solids, and then discusses carrier statistics for semiconductors in thermal equilibrium. Of course a solid cannot be in true thermodynamic equilibrium if any electrical current is passed; but when currents are reasonably small the distribution function is but little perturbed, and the carrier distribution for such a """"quasi-equilibrium"""" co

  10. Conductive polymer nanocomposites with hierarchical multi-scale structures via self-assembly of carbon-nanotubes on graphene on polymer-microspheres

    Science.gov (United States)

    Tang, Changyu; Long, Gucheng; Hu, Xin; Wong, Ka-Wai; Lau, Woon-Ming; Fan, Meikun; Mei, Jun; Xu, Tao; Wang, Bin; Hui, David

    2014-06-01

    A novel and highly conductive 3-dimensional (3D) hierarchical multi-scale structure is formed by a new, simple, facile, and water-based method that enables practical production of conductive carbon nanofiller/polymer composites. More specifically, the π-π interaction between CNTs and graphene oxide (GO) is exploited to disperse conductive but non-polar CNTs with amphiphilic GO sheets to form a stable aqueous colloidal solution. Aqueous-dispersible latex-polystyrene microspheres are then added to enable the self-assembly processes of anchoring CNTs on GO and wrapping microspheres with GO-stabilized CNTs for the formation of an intriguing 3D hierarchical multi-scale structure. During this process, GO is reduced to conductive reduced-graphene oxide (RGO). The resultant RGO sheets act as ``nano-walls'' to prevent CNTs from randomly diffusing into the polymer bulk during thermal pressing of RGO-CNT/microspheres, which results in the formation of a 3D foam-like network of RGO-CNTs with high quality. The resultant composite with such a structure gives an ultra-low percolation threshold (0.03 vol% RGO-CNTs) and a reasonably high conductivity (153 S m-1 at 4 vol% RGO-CNTs), which could satisfy various applications requiring both transparency and electrical conduction characteristics (e.g. transparent antistatic coatings, capacitive touch-screens, and transparent electronic devices).A novel and highly conductive 3-dimensional (3D) hierarchical multi-scale structure is formed by a new, simple, facile, and water-based method that enables practical production of conductive carbon nanofiller/polymer composites. More specifically, the π-π interaction between CNTs and graphene oxide (GO) is exploited to disperse conductive but non-polar CNTs with amphiphilic GO sheets to form a stable aqueous colloidal solution. Aqueous-dispersible latex-polystyrene microspheres are then added to enable the self-assembly processes of anchoring CNTs on GO and wrapping microspheres with GO

  11. SEMICONDUCTOR DEVICES Density-controllable nonvolatile memory devices having metal nanocrystals through chemical synthesis and assembled by spin-coating technique

    Science.gov (United States)

    Guangli, Wang; Yubin, Chen; Yi, Shi; Lin, Pu; Lijia, Pan; Rong, Zhang; Youdou, Zheng

    2010-12-01

    A novel two-step method is employed, for the first time, to fabricate nonvolatile memory devices that have metal nanocrystals. First, size-averaged Au nanocrystals are synthesized chemically; second, they are assembled into memory devices by a spin-coating technique at room temperature. This attractive approach makes it possible to tailor the diameter and control the density of nanocrystals individually. In addition, processes at room temperature prevent Au diffusion, which is a main concern for the application of metal nanocrystal-based memory. The experimental results, both the morphology characterization and the electrical measurements, reveal that there is an optimum density of nanocrystal monolayer to balance between long data retention and a large hysteresis memory window. At the same time, density-controllable devices could also feed the preferential emphasis on either memory window or retention time. All these facts confirm the advantages and novelty of our two-step method.

  12. Survey of semiconductor physics

    CERN Document Server

    Böer, Karl W

    1992-01-01

    Any book that covers a large variety of subjects and is written by one author lacks by necessity the depth provided by an expert in his or her own field of specialization. This book is no exception. It has been written with the encouragement of my students and colleagues, who felt that an extensive card file I had accumulated over the years of teaching solid state and semiconductor physics would be helpful to more than just a few of us. This file, updated from time to time, contained lecture notes and other entries that were useful in my research and permitted me to give to my students a broader spectrum of information than is available in typical textbooks. When assembling this material into a book, I divided the top­ ics into material dealing with the homogeneous semiconductor, the subject of the previously published Volume 1, and the inhomoge­ neous semiconductor, the subject of this Volume 2. In order to keep the book to a manageable size, sections of tutorial character which can be used as text for a g...

  13. Survey of cryogenic semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Talarico, L.J.; McKeever, J.W.

    1996-04-01

    Improved reliability and electronic performance can be achieved in a system operated at cryogenic temperatures because of the reduction in mechanical insult and in disruptive effects of thermal energy on electronic devices. Continuing discoveries of new superconductors with ever increasing values of T{sub c} above that of liquid nitrogen temperature (LNT) have provided incentive for developing semiconductor electronic systems that may also operate in the superconductor`s liquid nitrogen bath. Because of the interest in high-temperature superconductor (HTS) devices, liquid nitrogen is the cryogen of choice and LNT is the temperature on which this review is focused. The purpose of this survey is to locate and assemble published information comparing the room temperature (298 K), performance of commercially available conventional and hybrid semiconductor device with their performance at LNT (77K), to help establish their candidacy as cryogenic electronic devices specifically for use at LNT. The approach to gathering information for this survey included the following activities. Periodicals and proceedings were searched for information on the behavior of semiconductor devices at LNT. Telephone calls were made to representatives of semiconductor industries, to semiconductor subcontractors, to university faculty members prominent for their research in the area of cryogenic semiconductors, and to representatives of the National Aeronautics and Space Administration (NASA) and NASA subcontractors. The sources and contacts are listed with their responses in the introduction, and a list of references appears at the end of the survey.

  14. Supramolecular-templated synthesis of mesoporous silica-zirconia nanocomposite

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Mesoporous SiO2-ZrO2 nanocomposite was successfully prepared by using supramolecular triblock copolymer as the template through evaporation-induced self-assembly approach. The textural and structural properties were characterized by X-ray diffraction, nitrogen adsorption analysis, and transmission electron microscope.Comparison between pure mesoporous silica and mesoporous silica-zirconia nanocomposite was also presented in this work. The surface area, pore size, and pore volume decreased as the Zr doping in the mesoporous silica framework. But the obtained nanocomposite maintained the cubic Im3m-type mesoporous structure.

  15. Semiconductor sensors

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, Frank, E-mail: frank.hartmann@cern.c [Institut fuer Experimentelle Kernphysik, KIT, Wolfgang-Gaede-Str. 1, Karlsruhe 76131 (Germany)

    2011-02-01

    Semiconductor sensors have been around since the 1950s and today, every high energy physics experiment has one in its repertoire. In Lepton as well as Hadron colliders, silicon vertex and tracking detectors led to the most amazing physics and will continue doing so in the future. This contribution tries to depict the history of these devices exemplarily without being able to honor all important developments and installations. The current understanding of radiation damage mechanisms and recent R and D topics demonstrating the future challenges and possible technical solutions for the SLHC detectors are presented. Consequently semiconductor sensor candidates for an LHC upgrade and a future linear collider are also briefly introduced. The work presented here is a collage of the work of many individual silicon experts spread over several collaborations across the world.

  16. Semiconductor Optics

    CERN Document Server

    Klingshirn, Claus F

    2012-01-01

    This updated and enlarged new edition of Semiconductor Optics provides an introduction to and an overview of semiconductor optics from the IR through the visible to the UV, including linear and nonlinear optical properties, dynamics, magneto and electrooptics, high-excitation effects and laser processes, some applications, experimental techniques and group theory. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered extend from physics to materials science and optoelectronics. Significantly updated chapters add coverage of current topics such as electron hole plasma, Bose condensation of excitons and meta materials. Over 120 problems, chapter introductions and a detailed index make it the key textbook for graduate students in physics. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered ...

  17. Semiconductor Spintronics

    OpenAIRE

    Fabian, J.; Matos-Abiague, A.; Ertler, C.; Stano, P.; Zutic, I.

    2007-01-01

    Spintronics refers commonly to phenomena in which the spin of electrons in a solid state environment plays the determining role. In a more narrow sense spintronics is an emerging research field of electronics: spintronics devices are based on a spin control of electronics, or on an electrical and optical control of spin or magnetism. This review presents selected themes of semiconductor spintronics, introducing important concepts in spin transport, spin injection, Silsbee-Johnson spin-charge ...

  18. Semiconductor Thermistors

    OpenAIRE

    McCammon, Dan

    2005-01-01

    Semiconductor thermistors operating in the variable range hopping conduction regime have been used in thermal detectors of all kinds for more than fifty years. Their use in sensitive bolometers for infrared astronomy was a highly developed empirical art even before the basic physics of the conduction mechanism was understood. Today we are gradually obtaining a better understanding of these devices, and with improvements in fabrication technologies thermometers can now be designed and built wi...

  19. Flexible magnetic nanoparticles-reduced graphene oxide composite membranes formed by self-assembly in solution.

    Science.gov (United States)

    Zhu, Guoxing; Liu, Yuanjun; Xu, Zheng; Jiang, Tian; Zhang, Chi; Li, Xun; Qi, Gang

    2010-08-01

    A facile and robust route for the pre-synthesized Fe(3)O(4) nanoparticles (NPs) exclusively assembled on both sides of reduced graphene oxide (RGO) sheets with tunable density forming two-dimensional NPs composite membranes is developed in solution. The assembly is driven by electrostatic attraction, and the nanocomposite sheets display considerable mechanical robustness, such as it can sustain supersonic and solvothermal treatments without NPs falling off, also, can freely float in solution and curl into a tube. The obtained two-dimensional composite grain membranes exhibit superparamagnetic behavior at room temperature but responds astutely to an external magnetic field. In addition, these magnetic composite membranes show an enhanced absorption capability for microwaves. The grain sheets are attractive for biomedical, sensors, environmental applications and electric-magnetic devices benefited from large surfaces, high magnetization moment, and superparamagnetic properties. The effective integration of oxide nanocrystals on RGO sheets provides a new way to design semiconductor-carbon nanocomposites for nanodevices or catalytic applications. PMID:20572256

  20. Semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Ito, K.; Shyuue, M.

    1982-09-25

    A distributed feedback semiconductor laser is proposed which generates several beams with equal wavelengths in different directions. For this purpose, 1 millimeter grooves are cut into the surface of an n-type conductance GaAs plate in three different directions; these grooves form a diffraction grating. The center of this plate has no grooves and is bombarded by an He/Ne laser beam. The diffraction gratings provide resonance properties and generate laser beams with wavelengths of 8850, 9000 and 9200 angstroms.

  1. Fibre reinforced polymer nanocomposites

    OpenAIRE

    Vlasveld, D.P.N.

    2005-01-01

    In this thesis the results are described of the research on a combination of two types of composites: thermoplastic nanocomposites and continuous fibre composites. In this three-phase composite the main reinforcing phase are continuous glass or carbon fibres, and the matrix consists of a polyamide 6 / layered silicate nanocomposite. To be able to produce and understand this new type of thermoplastic composite, the properties of the nanocomposite matrix materials have been investigated, follow...

  2. Superhard Nanocomposite Coatings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The recent development in the field of nanocomposite coatings with good mechanical properties is critically reviewed in this paper. The design principle and materials selection for the nanocomposite coatings are introduced. Different methods for the preparation of superhard nanocomposite coatings are described with emphasis on the magnetron sputtering. Based on recent theoretical and experimental results regarding the appearance of superhardness in nanocomposite coating, lattice parameter changes, crystallite size, microstructure and morphology are reviewed in detail. Also emphasized are the mechanical properties (especially on hardness) and the ways by which the properties are derived.

  3. Magnetic nanocomposite sensor

    KAUST Repository

    Alfadhel, Ahmed

    2016-05-06

    A magnetic nanocomposite device is described herein for a wide range of sensing applications. The device utilizes the permanent magnetic behavior of the nanowires to allow operation without the application of an additional magnetic field to magnetize the nanowires, which simplifies miniaturization and integration into microsystems. In5 addition, the nanocomposite benefits from the high elasticity and easy patterning of the polymer-based material, leading to a corrosion-resistant, flexible material that can be used to realize extreme sensitivity. In combination with magnetic sensor elements patterned underneath the nanocomposite, the nanocomposite device realizes highly sensitive and power efficient flexible artificial cilia sensors for flow measurement or tactile sensing.

  4. Power semiconductors

    CERN Document Server

    Kubát, M

    1984-01-01

    The book contains a summary of our knowledge of power semiconductor structures. It presents first a short historic introduction (Chap. I) as well as a brief selection of facts from solid state physics, in particular those related to power semiconductors (Chap. 2). The book deals with diode structures in Chap. 3. In addition to fundamental facts in pn-junction theory, the book covers mainly the important processes of power structures. It describes the emitter efficiency and function of microleaks (shunts). the p +p and n + n junctions, and in particular the recent theory of the pin, pvn and p1tn junctions, whose role appears to be decisive for the forward mode not only of diode structures but also of more complex ones. For power diode structures the reverse mode is the decisive factor in pn-junction breakdown theory. The presentation given here uses engineering features (the multiplication factor M and the experimentally detected laws for the volume and surface of crystals), which condenses the presentation an...

  5. Magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bihler, Christoph

    2009-04-15

    In this thesis we investigated in detail the properties of Ga{sub 1-x}Mn{sub x}As, Ga{sub 1-x}Mn{sub x}P, and Ga{sub 1-x}Mn{sub x}N dilute magnetic semiconductor thin films with a focus on the magnetic anisotropy and the changes of their properties upon hydrogenation. We applied two complementary spectroscopic techniques to address the position of H in magnetic semiconductors: (i) Electron paramagnetic resonance, which provides direct information on the symmetry of the crystal field of the Mn{sup 2+} atoms and (ii) x-ray absorption fine structure analysis which allows to probe the local crystallographic neighborhood of the absorbing Mn atom via analysing the fine structure at the Mn K absorption edge. Finally, we discussed the obstacles that have to be overcome to achieve Curie temperatures above the current maximum in Ga{sub 1-x}Mn{sub x}As of 185 K. Here, we outlined in detail the generic problem of the formation of precipitates at the example of Ge:MN. (orig.)

  6. Investigation of Transport and Recombination Properties in Graphene/Titanium Dioxide Nanocomposite for Dye-Sensitized Solar Cell Photoanodes

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: In this paper, we present the fabrication and characterization of Dye-Sensitized Solar Cells exploiting graphene/TiO2 nanocomposite photoanodes produced by in-situ catalytic reduction of graphene oxide. The graphene oxide reduction to graphene was obtained in a solution-based process during the thermal treatment of the composite, catalyzed by the presence of TiO2 nanoparticles, as confirmed by X-ray photoelectron spectroscopy. The carbon nanostructures act as 2D conductive support path for the photogenerated electrons inside the nanostructured semiconductor electrode, as evidenced by the charge transport properties and recombination kinetics estimated by electrochemical impedance spectroscopy. The presence of graphene sheets led to an increase of the electron lifetime, due to reduction of recombination of charge carriers; moreover, the devices assembled with nanocomposite photoanodes showed an increase of the generated photocurrent, due to the improvement of the transport properties. The optimal value of graphene oxide in TiO2 was found at a concentration of 0.25 wt%, which corresponds to double photoconversion efficiency with respect to the bare TiO2-based cells

  7. Graphitic design: prospects of graphene-based nanocomposites for solar energy conversion, storage, and sensing.

    Science.gov (United States)

    Lightcap, Ian V; Kamat, Prashant V

    2013-10-15

    Graphene not only possesses interesting electrochemical behavior but also has a remarkable surface area and mechanical strength and is naturally abundant, all advantageous properties for the design of tailored composite materials. Graphene-semiconductor or -metal nanoparticle composites have the potential to function as efficient, multifunctional materials for energy conversion and storage. These next-generation composite systems could possess the capability to integrate conversion and storage of solar energy, detection, and selective destruction of trace environmental contaminants or achieve single-substrate, multistep heterogeneous catalysis. These advanced materials may soon become a reality, based on encouraging results in the key areas of energy conversion and sensing using graphene oxide as a support structure. Through recent advances, chemists can now integrate such processes on a single substrate while using synthetic designs that combine simplicity with a high degree of structural and composition selectivity. This progress represents the beginning of a transformative movement leveraging the advancements of single-purpose chemistry toward the creation of composites designed to address whole-process applications. The promising field of graphene nanocomposites for sensing and energy applications is based on fundamental studies that explain the electronic interactions between semiconductor or metal nanoparticles and graphene. In particular, reduced graphene oxide is a suitable composite substrate because of its two-dimensional structure, outstanding surface area, and electrical conductivity. In this Account, we describe common assembly methods for graphene composite materials and examine key studies that characterize its excited state interactions. We also discuss strategies to develop graphene composites and control electron capture and transport through the 2D carbon network. In addition, we provide a brief overview of advances in sensing, energy conversion

  8. Rapid fabrication of hierarchically structured supramolecular nanocomposite thin films in one minute.

    Science.gov (United States)

    Kao, Joseph; Thorkelsson, Kari; Bai, Peter; Zhang, Zhen; Sun, Cheng; Xu, Ting

    2014-01-01

    Functional nanocomposites containing nanoparticles of different chemical compositions may exhibit new properties to meet demands for advanced technology. It is imperative to simultaneously achieve hierarchical structural control and to develop rapid, scalable fabrication to minimize degradation of nanoparticle properties and for compatibility with nanomanufacturing. Here we show that the assembly kinetics of supramolecular nanocomposites in thin films are governed by the energetic cost arising from defects, the chain mobility and the activation energy for inter-domain diffusion. By optimizing only one parameter, the solvent fraction in the film, the assembly kinetics can be precisely tailored to produce hierarchically structured thin films of supramolecular nanocomposites in one minute. Moreover, the strong wavelength-dependent optical anisotropy in the nanocomposite highlights their potential applications for light manipulation and information transmission. The present study may open a new avenue in designing manufacture-friendly continuous processing for the fabrication of functional nanocomposite thin films. PMID:24887144

  9. Novel hollow Pt-ZnO nanocomposite microspheres with hierarchical structure and enhanced photocatalytic activity and stability

    Science.gov (United States)

    Yu, Changlin; Yang, Kai; Xie, Yu; Fan, Qizhe; Yu, Jimmy C.; Shu, Qing; Wang, Chunying

    2013-02-01

    Noble metal/semiconductor nanocomposites play an important role in high efficient photocatalysis. Herein, we demonstrate a facile strategy for fabrication of hollow Pt-ZnO nanocomposite microspheres with hierarchical structure under mild solvothermal conditions using Zn (CH3COO)2.2H2O and HPtCl4 as the precursors, and polyethylene glycol-6000 (PEG-6000) and ethylene glycol as the reducing agent and solvent, respectively. The as-synthesized ZnO and Pt-ZnO composite nanocrystals were well characterized by powder X-ray diffraction (XRD), nitrogen-physical adsorption, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS), and photoluminescence (PL) emission spectroscopy. It was found that Pt content greatly influences the morphology of Pt-ZnO composite nanocrystals. Suitable concentration of HPtCl4 in the reaction solution system can produce well hierarchically hollow Pt-ZnO nanocomposite microspheres, which are composed of an assembly of fine Pt-ZnO nanocrystals. Photocatalytic tests of the Pt-ZnO microspheres for the degradation of the dye acid orange II revealed extremely high photocatalytic activity and stability compared with those of pure ZnO and corresponding Pt deposited ZnO. The remarkable photocatalytic performance of hollow Pt-ZnO microspheres mainly originated from their unique nanostructures and the low recombination rate of the e-/h+ pairs by the platinum nanoparticles embedded in ZnO nanocrystals.Noble metal/semiconductor nanocomposites play an important role in high efficient photocatalysis. Herein, we demonstrate a facile strategy for fabrication of hollow Pt-ZnO nanocomposite microspheres with hierarchical structure under mild solvothermal conditions using Zn (CH3COO)2.2H2O and HPtCl4 as the precursors, and polyethylene glycol-6000 (PEG-6000) and ethylene glycol as the reducing agent and solvent, respectively. The as

  10. Surface Properties and Photocatalytic Activity of KTaO3, CdS, MoS2 Semiconductors and Their Binary and Ternary Semiconductor Composites

    OpenAIRE

    Beata Bajorowicz; Anna Cybula; Winiarski, Michał J.; Tomasz Klimczuk; Adriana Zaleska

    2014-01-01

    Single semiconductors such as KTaO3, CdS MoS2 or their precursor solutions were combined to form novel binary and ternary semiconductor nanocomposites by the calcination or by the hydro/solvothermal mixed solutions methods, respectively. The aim of this work was to study the influence of preparation method as well as type and amount of the composite components on the surface properties and photocatalytic activity of the new semiconducting photoactive materials. We presented different binary a...

  11. Tuning and synthesis of semiconductor nanostructures by mechanical compression

    Science.gov (United States)

    Fan, Hongyou; Li, Binsong

    2015-11-17

    A mechanical compression method can be used to tune semiconductor nanoparticle lattice structure and synthesize new semiconductor nanostructures including nanorods, nanowires, nanosheets, and other three-dimensional interconnected structures. II-VI or IV-VI compound semiconductor nanoparticle assemblies can be used as starting materials, including CdSe, CdTe, ZnSe, ZnS, PbSe, and PbS.

  12. Volumetric composition of nanocomposites

    DEFF Research Database (Denmark)

    Madsen, Bo; Lilholt, Hans; Mannila, Juha;

    2015-01-01

    Detailed characterisation of the properties of composite materials with nanoscale fibres is central for the further progress in optimization of their manufacturing and properties. In the present study, a methodology for the determination and analysis of the volumetric composition of nanocomposites...... is presented, using cellulose/epoxy and aluminosilicate/polylactate nanocomposites as case materials. The buoyancy method is used for the accurate measurements of materials density. The accuracy of the method is determined to be high, allowing the measured nanocomposite densities to be reported with 5...... significant figures. The plotting of the measured nanocomposite density as a function of the nanofibre weight content is shown to be a first good approach of assessing the porosity content of the materials. The known gravimetric composition of the nanocomposites is converted into a volumetric composition...

  13. Aqueous synthesis of ZnTe/dendrimer nanocomposites and their antimicrobial activity: implications in therapeutics

    Science.gov (United States)

    Ghosh, S.; Ghosh, D.; Bag, P. K.; Bhattacharya, S. C.; Saha, A.

    2011-03-01

    The present strategy proposes a simple and single step aqueous route for synthesizing stable, fluorescent ZnTe/dendrimer nanocomposites with varying dendrimer terminal groups. In these hybrid materials, the fluorescence of the semiconductor combines with the biomimetic properties of the dendrimer making them suitable for various biomedical applications. The ZnTe nanocomposites thus obtained demonstrate bactericidal activity against enteropathogenic bacteria without having toxic effects on the human erythrocytes. The average size of the ZnTe nanoparticles within the dendrimer matrix was in the range of 2.9-6.0 nm, and they have a good degree of crystallinity with a hexagonal crystal phase. The antibacterial activities of the ZnTe/dendrimer nanocomposites (ZnTe DNCs) as well other semiconductor nanocomposites were evaluated against enteropathogenic bacteria including multi-drug resistant Vibrio cholerae serogroup O1 and enterotoxigenic Escherichia coli (ETEC). ZnTe DNCs had significant antibacterial activity against strains of V. cholerae and ETEC with minimum inhibitory concentrations ranging from 64 to 512 μg ml-1 and minimum bactericidal concentrations ranging from 128 to 1000 μg ml-1. Thus, the observed results suggest that these water-soluble active nanocomposites have potential for the treatment of enteric diseases like diarrhoea and cholera.The present strategy proposes a simple and single step aqueous route for synthesizing stable, fluorescent ZnTe/dendrimer nanocomposites with varying dendrimer terminal groups. In these hybrid materials, the fluorescence of the semiconductor combines with the biomimetic properties of the dendrimer making them suitable for various biomedical applications. The ZnTe nanocomposites thus obtained demonstrate bactericidal activity against enteropathogenic bacteria without having toxic effects on the human erythrocytes. The average size of the ZnTe nanoparticles within the dendrimer matrix was in the range of 2.9-6.0 nm, and they

  14. Electron beam pumped semiconductor laser

    Science.gov (United States)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2009-01-01

    Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

  15. Semiconductor laser. Halbleiterlaser

    Energy Technology Data Exchange (ETDEWEB)

    Wuenstel, K.; Gohla, B.; Tegude, F.; Luz, G.; Hildebrand, O.

    1987-08-27

    A highly modulable semiconductor laser and a process for its manufacture are described. The semiconductor laser has a substrate, a stack of semiconductor layers and electrical contacts. To reduce the capacity, the width of the stack of semiconductor layers is reduced at the sides by anisotropic etching. The electrical contacts are situated on the same side of the substrate and are applied in the same stage of the process. The semiconductor laser is suitable for monolithic integration in other components.

  16. Organic / IV, III-V Semiconductor Hybrid Solar Cells

    Directory of Open Access Journals (Sweden)

    Pang-Leen Ong

    2010-03-01

    Full Text Available We present a review of the emerging class of hybrid solar cells based on organic-semiconductor (Group IV, III-V, nanocomposites, which states separately from dye synthesized, polymer-metal oxides and organic-inorganic (Group II-VI nanocomposite photovoltaics. The structure of such hybrid cell comprises of an organic active material (p-type deposited by coating, printing or spraying technique on the surface of bulk or nanostructured semiconductor (n-type forming a heterojunction between the two materials. Organic components include various photosensitive monomers (e.g., phtalocyanines or porphyrines, conjugated polymers, and carbon nanotubes. Mechanisms of the charge separation at the interface and their transport are discussed. Also, perspectives on the future development of such hybrid cells and comparative analysis with other classes of photovoltaics of third generation are presented.

  17. Chromatic Mechanical Response in 2-D Layered Transition Metal Dichalcogenide (TMDs) based Nanocomposites

    Science.gov (United States)

    Rahneshin, Vahid; Khosravi, Farhad; Ziolkowska, Dominika A.; Jasinski, Jacek B.; Panchapakesan, Balaji

    2016-10-01

    The ability to convert photons of different wavelengths directly into mechanical motion is of significant interest in many energy conversion and reconfigurable technologies. Here, using few layer 2H-MoS2 nanosheets, layer by layer process of nanocomposite fabrication, and strain engineering, we demonstrate a reversible and chromatic mechanical response in MoS2-nanocomposites between 405 nm to 808 nm with large stress release. The chromatic mechanical response originates from the d orbitals and is related to the strength of the direct exciton resonance A and B of the few layer 2H-MoS2 affecting optical absorption and subsequent mechanical response of the nanocomposite. Applying uniaxial tensile strains to the semiconducting few-layer 2H-MoS2 crystals in the nanocomposite resulted in spatially varying energy levels inside the nanocomposite that enhanced the broadband optical absorption up to 2.3 eV and subsequent mechanical response. The unique photomechanical response in 2H-MoS2 based nanocomposites is a result of the rich d electron physics not available to nanocomposites based on sp bonded graphene and carbon nanotubes, as well as nanocomposite based on metallic nanoparticles. The reversible strain dependent optical absorption suggest applications in broad range of energy conversion technologies that is not achievable using conventional thin film semiconductors.

  18. Plasmonic, excitonic and exciton-plasmonic photoinduced nanocomposites

    Science.gov (United States)

    Bityurin, N.; Ermolaev, N.; Smirnov, A. A.; Afanasiev, A.; Agareva, N.; Koryukina, T.; Bredikhin, V.; Kamensky, V.; Pikulin, A.; Sapogova, N.

    2016-03-01

    UV irradiation of materials consisting of a polymer matrix that possesses precursors of different kinds can result in creation of nanoparticles within the irradiated domains. Such photoinduced nanocomposites are promising for photonic applications due to the strong alteration of their optical properties compared to initial non-irradiated materials. We report our results on the synthesis and investigation of plasmonic, excitonic and exciton-plasmonic photoinduced nanocomposites. Plasmonic nanocomposites contain metal nanoparticles of noble metals with a pronounced plasmon resonance. Excitonic nanocomposites possess semiconductor nanoclusters (quantum dots). We consider the CdS-Au pair because the luminescent band of CdS nanoparticles enters the plasmon resonance band of gold nanoparticles. The obtaining of such particles within the same composite materials is promising for the creation of media with exciton-plasmon resonance. We demonstrate that it is possible to choose appropriate precursor species to obtain the initially transparent poly(methyl methacrylate) (PMMA) films containing both types of these molecules either separately or together. Proper irradiation of these materials by a light-emitting diode operating at the wavelength of 365 nm provides material alteration demonstrating light-induced optical absorption and photoluminescent properties typical for the corresponding nanoparticles. Thus, an exciton-plasmonic photoinduced nanocomposite is obtained. It is important that here we use the precursors that are different from those usually employed.

  19. Semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Marstein Erik Stensrud

    2003-07-01

    This thesis presents a study of two material systems containing semiconductor nanocrystals, namely porous silicon (PSi) films and germanium (Ge) nanocrystals embedded in silicon dioxide (SiO2) films. The PSi films were made by anodic etching of silicon (Si) substrates in an electrolyte containing hydrofluoric acid. The PSi films were doped with erbium (Er) using two different doping methods. electrochemical doping and doping by immersing the PSi films in a solution containing Er. The resulting Er concentration profiles were investigated using scanning electron microscopy (SEN1) combined with energy dispersive X-ray analysis (EDS). The main subject of the work on PSi presented in this thesis was investigating and comparing these two doping methods. Ge nanocrystals were made by implanting Ge ions into Si02 films that were subsequently annealed. However. nanocrystal formation occurred only for certain sets of processing parameters. The dependence of the microstructure of the Ge implanted Si02 films on the processing parameters were therefore investigated. A range of methods were employed for these investigations, including transmission electron microscopy (TEM) combined with EDS, X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The observed structures, ranging from Ge nanocrystals to voids with diameters of several tens of nanometers and Ge rich Si02 films without any nanocrystals is described. A model explaining the void formation is also presented. For certain sets of processing parameters. An accumulation of Ge at the Si-Si02 interface was observed. The effect of this accumulation on the electrical properties of MOS structures made from Ge implanted SiO2 films was investigated using CV-measurements. (Author)

  20. Tribology of Nanocomposites

    CERN Document Server

    2013-01-01

    This book provides recent information on nanocomposites tribology. Chapter 1 provides information on tribology of bulk polymer nanocomposites and nanocomposite coatings. Chapter 2 is dedicated to nano and micro PTFE for surface lubrication of carbon fabric reinforced polyethersulphone composites. Chapter 3 describes Tribology of MoS2 -based nanocomposites. Chapter 4 contains information on friction and wear of Al2O2 -based composites with dispersed and agglomerated nanoparticles. Finally, chapter 5 is dedicated to wear of multi-scale phase reinforced composites. It is a useful reference for academics, materials and physics researchers, materials, mechanical and manufacturing engineers, both as final undergraduate and postgraduate levels. It is a useful reference for academics, materials and physics researchers, materials, mechanical and manufacturing engineers, both as final undergraduate and postgraduate levels.

  1. Nanocomposite thermite ink

    Energy Technology Data Exchange (ETDEWEB)

    Tappan, Alexander S. (Albuquerque, NM); Cesarano, III, Joseph (Albuquerque, NM); Stuecker, John N. (Albuquerque, NM)

    2011-11-01

    A nanocomposite thermite ink for use in inkjet, screen, and gravure printing. Embodiments of this invention do not require separation of the fuel and oxidizer constituents prior to application of the ink to the printed substrate.

  2. Nano-composite materials

    Science.gov (United States)

    Lee, Se-Hee; Tracy, C. Edwin; Pitts, J. Roland

    2010-05-25

    Nano-composite materials are disclosed. An exemplary method of producing a nano-composite material may comprise co-sputtering a transition metal and a refractory metal in a reactive atmosphere. The method may also comprise co-depositing a transition metal and a refractory metal composite structure on a substrate. The method may further comprise thermally annealing the deposited transition metal and refractory metal composite structure in a reactive atmosphere.

  3. Handbook of spintronic semiconductors

    CERN Document Server

    Chen, Weimin

    2010-01-01

    Offers a review of the field of spintronic semiconductors. This book covers a range of topics, including growth and basic physical properties of diluted magnetic semiconductors based on II-VI, III-V and IV semiconductors, developments in theory and experimental techniques and potential device applications.

  4. Photoelectrosynthesis at semiconductor electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Nozik, A. J.

    1980-12-01

    The general principles of photoelectrochemistry and photoelectrosynthesis are reviewed and some new developments in photoelectrosynthesis are discussed. Topics include energetics of semiconductor-electrolyte interfaces(band-edge unpinning); hot carrier injection at illuminated semiconductor-electrolyte junctions; derivatized semiconductor electrodes; particulate photoelectrochemical systems; layered compounds and other new materials; and dye sensitization. (WHK)

  5. Hierarchical Nanocomposites for Device Applications

    Science.gov (United States)

    Watkins, James

    We have outlined templating strategies for electronic and optical device fabrication that include self-assembly of well-ordered polymer/nanoparticle hybrids and nanoimprint lithography using novel materials sets. Using additive-driven self-assembly, for example, we demonstrate the formation of periodic nanocomposites with tunable magnetic and optical characteristics containing up to 70 wt. % of metal, metal oxide and/or semiconducting nanoparticles through phase specific interactions of the particles with either linear block copolymer or brush block copolymer (BBCP) templates. The BBCP templates provide direct access to large domain spacings for optical applications and spontaneous alignment within large volume elements. We have further developed highly filled nanoparticle/polymer hybrids for applications that require tailored dielectric constant or refractive index and a new imprinting process that allows direct printing of patterned 2-D and 3-D crystalline metal oxide films and composites with feature sizes of less than 100 nm. Applications in flexible electronics, light and energy management, and sensors and will be discussed.

  6. Perovskite LaFeO3/montmorillonite nanocomposites: synthesis, interface characteristics and enhanced photocatalytic activity

    Science.gov (United States)

    Peng, Kang; Fu, Liangjie; Yang, Huaming; Ouyang, Jing

    2016-01-01

    Perovskite LaFeO3/montmorillonite nanocomposites (LaFeO3/MMT) have been successfully prepared via assembling LaFeO3 nanoparticles on the surface of montmorillonite with citric acid assisted sol-gel method. The results indicated that the uniform LaFeO3 nanoparticles were densely deposited onto the surface of montmorillonite, mainly ranging in diameter from 10 nm to 15 nm. The photocatalytic activity of LaFeO3/MMT was evaluated by the degradation of Rhodamine B (RhB) under visible light irradiation, indicating that LaFeO3/MMT exhibited remarkable adsorption efficiency and excellent photocatalytic activity with the overall removal rate of RhB up to 99.34% after visible light irradiation lasting for 90 min. The interface characteristic and possible degradation mechanism were explored. The interface characterization of LaFeO3/MMT suggested that LaFeO3 nanoparticles could be immobilized on the surface of montmorillonite with the Si-O-Fe bonds. The abundant hydroxyl groups of montmorillonite, semiconductor photocatalysis of LaFeO3 and Fenton-like reaction could enhance the photocatalytic degradation through a synergistic effect. Therefore, the LaFeO3/MMT is a very promising photocatalyst in future industrial application to treat effectively wastewater of dyes.

  7. Unitary lens semiconductor device

    Science.gov (United States)

    Lear, Kevin L.

    1997-01-01

    A unitary lens semiconductor device and method. The unitary lens semiconductor device is provided with at least one semiconductor layer having a composition varying in the growth direction for unitarily forming one or more lenses in the semiconductor layer. Unitary lens semiconductor devices may be formed as light-processing devices such as microlenses, and as light-active devices such as light-emitting diodes, photodetectors, resonant-cavity light-emitting diodes, vertical-cavity surface-emitting lasers, and resonant cavity photodetectors.

  8. Hierarchical multifunctional nanocomposites

    Science.gov (United States)

    Ghasemi-Nejhad, Mehrdad N.

    2014-03-01

    Nanocomposites; including nano-materials such as nano-particles, nanoclays, nanofibers, nanotubes, and nanosheets; are of significant importance in the rapidly developing field of nanotechnology. Due to the nanometer size of these inclusions, their physicochemical characteristics differ significantly from those of micron size and bulk materials. The field of nanocomposites involves the study of multiphase materials where at least one of the constituent phases has one dimension less than 100 nm. This is the range where the phenomena associated with the atomic and molecular interaction strongly influence the macroscopic properties of materials. Since the building blocks of nanocomposites are at nanoscale, they have an enormous surface area with numerous interfaces between the two intermix phases. The special properties of the nano-composite arise from the interaction of its phases at the interface and/or interphase regions. By contrast, in a conventional composite based on micrometer sized filler such as carbon fibers, the interfaces between the filler and matrix constitutes have a much smaller surface-to-volume fraction of the bulk materials, and hence influence the properties of the host structure to a much smaller extent. The optimum amount of nanomaterials in the nanocomposites depends on the filler size, shape, homogeneity of particles distribution, and the interfacial bonding properties between the fillers and matrix. The promise of nanocomposites lies in their multifunctionality, i.e., the possibility of realizing unique combination of properties unachievable with traditional materials. The challenges in reaching this promise are tremendous. They include control over the distribution in size and dispersion of the nanosize constituents, and tailoring and understanding the role of interfaces between structurally or chemically dissimilar phases on bulk properties. While the properties of the matrix can be improved by the inclusions of nanomaterials, the

  9. Process, Structure, and Properties of Electrospun Carbon Nanotube-Reinforced Nanocomposite Yarns

    Directory of Open Access Journals (Sweden)

    Nasir M. Uddin

    2009-01-01

    Full Text Available Carbon nanotubes (CNTs are dispersed into polyacrylonitrile polymer solution and then assembled into continuous nanocomposite yarns through the drum-tape co-electrospinning process to facilitate the translation of CNT properties to higher order structures. We explore the dispersion of CNTs in a polymer matrix, the process of obtaining continuous yarn through electrospinning, and the surface morphology and mechanical properties of the nanocomposite yarn.

  10. Synthesis of copper polyacrylate nanocomposites by gamma irradiation

    International Nuclear Information System (INIS)

    This research involves the synthesis of copper nanoparticles with controlled size by the application of gamma radiation with varying polyacrylic acid (PAA) and CuSO4 concentration. An alternative and convenient method was done which employs Co60 irradiation of solutions of copper salt and PAA with irradiation dose of 1.6, 3.6, 6.4, and 9.2 MRad. The effect of polymer and copper sulfate's initial concentrations as well as the effect of the presence of alcohol as radical scavenger and the presence of ethylenediaminetetraacetic acid as stabilizer were evaluated. Characterization of nanocomposite properties such as plasmon resonance band, fluorescence, and particle morphology and size were determined. Layer-by-layer assembly of Cu-PAA nanocomposites and polydiallyl dimethyl ammonium chloride (PDDA) was also constructed. Stability of the synthesized copper-PAA nanocomposites in terms of the disappearance of plasmon band with time was evaluated. (Author)

  11. Formation of Nanoscale Composites of Compound Semiconductors Driven by Charge Transfer.

    Science.gov (United States)

    Gao, Weiwei; Dos Reis, Roberto; Schelhas, Laura T; Pool, Vanessa L; Toney, Michael F; Yu, Kin Man; Walukiewicz, Wladek

    2016-08-10

    Composites are a class of materials that are formed by mixing two or more components. These materials often have new functional properties compared to their constituent materials. Traditionally composites are formed by self-assembly due to structural dissimilarities or by engineering different layers or structures in the material. Here we report the synthesis of a uniform and stoichiometric composite of CdO and SnTe with a novel nanocomposite structure stabilized by the dissimilarity of the electronic band structure of the constituent materials. The composite has interesting electronic properties which range from highly n-type in CdO to semi-insulating in the intermediate composition range to highly p-type in SnTe. This can be explained by the overlap of the conduction and valence band of the constituent compounds. Ultimately, our work identifies a new class of composite semiconductors in which nanoscale self-organization is driven and stabilized by charge transfer between constituent materials.

  12. Formation of Nanoscale Composites of Compound Semiconductors Driven by Charge Transfer.

    Science.gov (United States)

    Gao, Weiwei; Dos Reis, Roberto; Schelhas, Laura T; Pool, Vanessa L; Toney, Michael F; Yu, Kin Man; Walukiewicz, Wladek

    2016-08-10

    Composites are a class of materials that are formed by mixing two or more components. These materials often have new functional properties compared to their constituent materials. Traditionally composites are formed by self-assembly due to structural dissimilarities or by engineering different layers or structures in the material. Here we report the synthesis of a uniform and stoichiometric composite of CdO and SnTe with a novel nanocomposite structure stabilized by the dissimilarity of the electronic band structure of the constituent materials. The composite has interesting electronic properties which range from highly n-type in CdO to semi-insulating in the intermediate composition range to highly p-type in SnTe. This can be explained by the overlap of the conduction and valence band of the constituent compounds. Ultimately, our work identifies a new class of composite semiconductors in which nanoscale self-organization is driven and stabilized by charge transfer between constituent materials. PMID:27459505

  13. Recent advances in clay mineral-containing nanocomposite hydrogels.

    Science.gov (United States)

    Zhao, Li Zhi; Zhou, Chun Hui; Wang, Jing; Tong, Dong Shen; Yu, Wei Hua; Wang, Hao

    2015-12-28

    Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE®, are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications.

  14. Developing New Nanoprobes from Semiconductor Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Aihua [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    In recent years, semiconductor nanocrystal quantum dots havegarnered the spotlight as an important new class of biological labelingtool. Withoptical properties superior to conventional organicfluorophores from many aspects, such as high photostability andmultiplexing capability, quantum dots have been applied in a variety ofadvanced imaging applications. This dissertation research goes along withlarge amount of research efforts in this field, while focusing on thedesign and development of new nanoprobes from semiconductor nanocrystalsthat are aimed for useful imaging or sensing applications not possiblewith quantum dots alone. Specifically speaking, two strategies have beenapplied. In one, we have taken advantage of the increasing capability ofmanipulating the shape of semiconductor nanocrystals by developingsemiconductor quantum rods as fluorescent biological labels. In theother, we have assembled quantum dots and gold nanocrystals into discretenanostructures using DNA. The background information and synthesis,surface manipulation, property characterization and applications of thesenew nanoprobes in a few biological experiments are detailed in thedissertation.

  15. Nanocomposite Strain Gauges Having Small TCRs

    Science.gov (United States)

    Gregory, Otto; Chen, Ximing

    2009-01-01

    Ceramic strain gauges in which the strain-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, strain gauges exhibit spurious thermally induced components of response denoted apparent strain. When temperature varies, a strain-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in strain. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent strain. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic strain gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.

  16. Semiconductor Physical Electronics

    CERN Document Server

    Li, Sheng

    2006-01-01

    Semiconductor Physical Electronics, Second Edition, provides comprehensive coverage of fundamental semiconductor physics that is essential to an understanding of the physical and operational principles of a wide variety of semiconductor electronic and optoelectronic devices. This text presents a unified and balanced treatment of the physics, characterization, and applications of semiconductor materials and devices for physicists and material scientists who need further exposure to semiconductor and photonic devices, and for device engineers who need additional background on the underlying physical principles. This updated and revised second edition reflects advances in semicondutor technologies over the past decade, including many new semiconductor devices that have emerged and entered into the marketplace. It is suitable for graduate students in electrical engineering, materials science, physics, and chemical engineering, and as a general reference for processing and device engineers working in the semicondi...

  17. Semiconductor Solar Superabsorbers

    OpenAIRE

    Yiling Yu; Lujun Huang; Linyou Cao

    2014-01-01

    Understanding the maximal enhancement of solar absorption in semiconductor materials by light trapping promises the development of affordable solar cells. However, the conventional Lambertian limit is only valid for idealized material systems with weak absorption, and cannot hold for the typical semiconductor materials used in solar cells due to the substantial absorption of these materials. Herein we theoretically demonstrate the maximal solar absorption enhancement for semiconductor materia...

  18. Semiconductor bridge (SCB) detonator

    Science.gov (United States)

    Bickes, Jr., Robert W.; Grubelich, Mark C.

    1999-01-01

    The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length.

  19. Fibre reinforced polymer nanocomposites

    NARCIS (Netherlands)

    Vlasveld, D.P.N.

    2005-01-01

    In this thesis the results are described of the research on a combination of two types of composites: thermoplastic nanocomposites and continuous fibre composites. In this three-phase composite the main reinforcing phase are continuous glass or carbon fibres, and the matrix consists of a polyamide 6

  20. Polyimide/carbon Nanocomposites

    Science.gov (United States)

    Harris, Frank W.

    2003-01-01

    The goal of this product is to design and characterize well-defined conductive nanocomposite materials. The materials will be composed of a polymer matrix composed of rigid-backbone polyimides, and will be filled with modified or unmodified multi-walled carbon nanotubes (MWNTs). The ultimate design of this project is to create composite materials with optical clarity and a high conductivity.

  1. Polyolefin nanocomposites in situ polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Galland, Griselda Barrera; Fim, Fabiana de C.; Milani, Marceo A.; Silva, Silene P. da; Forest, Tadeu; Radaelli, Gislaine, E-mail: griselda.barrera@ufrgs.br [Universidade Federal do Rio Grande de Sul - UFRGS, Porto Alegre, RS (Brazil); Basso, Nara R.S. [Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil); Quijada, Raul [Universidad de Chile, Santiago (Chile)

    2011-07-01

    Polyethylene and polypropylene nanocomposites using grapheme nanosheets and treated chrysotile have been synthesized by in situ polymerization using metallocene catalysts. The fillers have been submitted to acid, thermal and/ou ultrasound treatments before to introduce them into the polymerization reactor. A complete characterization of the fillers has been done. The nanocomposites have been characterized by SEM, TEM, DRX and AFM. The thermal, mechanic -dynamic, mechanical and electrical properties of the nanocomposites are discussed. (author)

  2. Third-order nonlinear optical response of Ag-CdSe/PVA hybrid nanocomposite

    Science.gov (United States)

    Tripathi, S. K.; Kaur, Ramneek; Kaur, Jaspreet; Sharma, Mamta

    2015-09-01

    Hybrid nanocomposites of II-VI semiconductor nanoparticles are gaining great interest in nonlinear optoelectronic devices. Present work includes the characterization of CdSe polymer nanocomposite prepared by chemical in situ technique. From X-ray diffraction, the hexagonal wurtzite structure of nanoparticles has been confirmed with spherical morphology from transmission electron microscopy. Ag-CdSe hybrid polymer nanocomposite has been prepared chemically at different Ag concentrations. The presence of Ag in hybrid nanocomposite has been confirmed with energy-dispersive X-ray spectroscopy. The effect of varying Ag concentration on the linear and nonlinear optical properties of the nanocomposites has been studied. In linear optical parameters, the linear absorption coefficient, refractive index, extinction coefficient and optical conductivity have been calculated. The third-order nonlinear optical properties have been observed with open- and closed-aperture Z-scan technique. The large nonlinear refractive index ~10-5 cm2/W with self-focusing behaviour is due to the combined effect of quantum confinement and thermo-optical effects. The enhanced nonlinearity with increasing Ag content is due to the surface plasmon resonance, which enhances the local electric field near the nanoparticle surface. Thus, Ag-CdSe hybrid polymer nanocomposite has favourable nonlinear optical properties for various optoelectronic applications.

  3. Third-order nonlinear optical response of Ag-CdSe/PVA hybrid nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, S.K.; Kaur, Ramneek; Kaur, Jaspreet; Sharma, Mamta [Panjab University, Department of Physics, Center of Advanced Study in Physics, Chandigarh (India)

    2015-09-15

    Hybrid nanocomposites of II-VI semiconductor nanoparticles are gaining great interest in nonlinear optoelectronic devices. Present work includes the characterization of CdSe polymer nanocomposite prepared by chemical in situ technique. From X-ray diffraction, the hexagonal wurtzite structure of nanoparticles has been confirmed with spherical morphology from transmission electron microscopy. Ag-CdSe hybrid polymer nanocomposite has been prepared chemically at different Ag concentrations. The presence of Ag in hybrid nanocomposite has been confirmed with energy-dispersive X-ray spectroscopy. The effect of varying Ag concentration on the linear and nonlinear optical properties of the nanocomposites has been studied. In linear optical parameters, the linear absorption coefficient, refractive index, extinction coefficient and optical conductivity have been calculated. The third-order nonlinear optical properties have been observed with open- and closed-aperture Z-scan technique. The large nonlinear refractive index ∝10{sup -5} cm{sup 2}/W with self-focusing behaviour is due to the combined effect of quantum confinement and thermo-optical effects. The enhanced nonlinearity with increasing Ag content is due to the surface plasmon resonance, which enhances the local electric field near the nanoparticle surface. Thus, Ag-CdSe hybrid polymer nanocomposite has favourable nonlinear optical properties for various optoelectronic applications. (orig.)

  4. Semiconductors data handbook

    CERN Document Server

    Madelung, Otfried

    2004-01-01

    This volume Semiconductors: Data Handbook contains frequently used data from the corresponding larger Landolt-Börnstein handbooks in a low price book for the individual scientist working in the laboratory. The Handbook contain important information about a large number of semiconductors

  5. Spin injection into semiconductors

    Science.gov (United States)

    Oestreich, M.; Hübner, J.; Hägele, D.; Klar, P. J.; Heimbrodt, W.; Rühle, W. W.; Ashenford, D. E.; Lunn, B.

    1999-03-01

    The injection of spin-polarized electrons is presently one of the major challenges in semiconductor spin electronics. We propose and demonstrate a most efficient spin injection using diluted magnetic semiconductors as spin aligners. Time-resolved photoluminescence with a Cd0.98Mn0.02Te/CdTe structure proves the feasibility of the spin-alignment mechanism.

  6. Applications of Semiconductor Lasers

    Institute of Scientific and Technical Information of China (English)

    LI Te; SUN Yan-fang; NING Yong-qiang; WANG Li-jun

    2005-01-01

    An overview of the applications of semiconductor lasers is presented. Diode lasers are widely used today,and the most prevalent use of the laser is probably in CD and DVD drives for computers and audio/video media systems. Semiconductor lasers are also used in many other fields ranging from optical fiber communications to display,medicine and pumping sources.

  7. Semiconductor radiation detection systems

    CERN Document Server

    2010-01-01

    Covers research in semiconductor detector and integrated circuit design in the context of medical imaging using ionizing radiation. This book explores other applications of semiconductor radiation detection systems in security applications such as luggage scanning, dirty bomb detection and border control.

  8. Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

    Science.gov (United States)

    Patel, Binay S.

    Epoxies are widely used as underfill resins throughout the microelectronics industry to mechanically couple and protect various components of flip-chip assemblies. Generally rigid materials largely surround underfill resins. Improving the mechanical and thermal properties of epoxy resins to better match those of their rigid counterparts can help extend the service lifetime of flip-chip assemblies. Recently, researchers have demonstrated that silica nanoparticles are effective toughening agents for lightly-crosslinked epoxies. Improvements in the fracture toughness of silica-filled epoxy nanocomposites have primarily been attributed to two toughening mechanisms: particle debonding with subsequent void growth and matrix shear banding. Various attempts have been made to model the contribution of these toughening mechanisms to the overall fracture energy observed in silica-filled epoxy nanocomposites. However, disparities still exist between experimental and modeled fracture energy results. In this dissertation, the thermal, rheological and mechanical behavior of eight different types of silica-filled epoxy nanocomposites was investigated. Each nanocomposite consisted of up to 10 vol% of silica nanoparticles with particle sizes ranging from 20 nm to 200 nm, with a variety of surface treatments and particle structures. Fractographical analysis was conducted with new experimental approaches in order to accurately identify morphological evidence for each proposed toughening mechanism. Overall, three major insights into the fracture behavior of real world silica-filled epoxy nanocomposites were established. First, microcracking was observed as an essential toughening mechanism in silica-filled epoxy nanocomposites. Microcracking was observed on the surface and subsurface of fractured samples in each type of silica-filled epoxy nanocomposite. The additional toughening contribution of microcracking to overall fracture energy yielded excellent agreement between experimental

  9. Compound Semiconductor Radiation Detectors

    CERN Document Server

    Owens, Alan

    2012-01-01

    Although elemental semiconductors such as silicon and germanium are standard for energy dispersive spectroscopy in the laboratory, their use for an increasing range of applications is becoming marginalized by their physical limitations, namely the need for ancillary cooling, their modest stopping powers, and radiation intolerance. Compound semiconductors, on the other hand, encompass such a wide range of physical and electronic properties that they have become viable competitors in a number of applications. Compound Semiconductor Radiation Detectors is a consolidated source of information on all aspects of the use of compound semiconductors for radiation detection and measurement. Serious Competitors to Germanium and Silicon Radiation Detectors Wide-gap compound semiconductors offer the ability to operate in a range of hostile thermal and radiation environments while still maintaining sub-keV spectral resolution at X-ray wavelengths. Narrow-gap materials offer the potential of exceeding the spectral resolutio...

  10. Controlling the reversible thermochromism of polydiacetylene/zinc oxide nanocomposites by varying alkyl chain length.

    Science.gov (United States)

    Chanakul, Amornsak; Traiphol, Nisanart; Traiphol, Rakchart

    2013-01-01

    In this work, polydiacetylene (PDA)/ZnO nanocomposites are successfully fabricated by using three types of monomers with different alkyl chain length, 5,7-hexadecadiynoic acid, 10,12-tricosadiynoic acid, and 10,12-pentacosadiynoic acid. The monomers dispersed in aqueous medium spontaneously assemble onto the surface of ZnO nanoparticles, promoted by strong interfacial interactions. The PDA/ZnO nanocomposites obtained via photopolymerization process are characterized by scanning electron microscopy, laser light scattering, infrared spectroscopy, and uv/vis absorption spectroscopy. The strength of interfacial interactions and morphologies of the nanocomposites are found to vary with alkyl chain length of the monomers. The PDA/ZnO nanocomposites also exhibit rather different thermochromic behaviors compared to their pure PDA counterparts. All nanocomposites show reversible blue/purple color transition upon multiple heating/cooling cycles, while the irreversible blue/red color transition is observed in the systems of pure PDAs. The shortening of alkyl side chain in PDA/ZnO nanocomposites leads to a systematic decrease in their color-transition temperatures. Colors of the nanocomposites at elevated temperature also vary with the alkyl chain length. Our results provide a simple route for controlling the reversible thermochromism of PDA-based materials, allowing their utilization in a wider range of applications. PMID:23058980

  11. Mesoporous C/CrN and C/VN Nanocomposites Obtained by One-Pot Soft-Templating Process

    Directory of Open Access Journals (Sweden)

    Julien Kiener

    2016-07-01

    Full Text Available Nanocomposites of ordered mesoporous carbon associated with chromium nitride (CrN or vanadium nitride (VN nanoparticles were obtained by a simple one-pot synthesis based on the solvent evaporation induced self-assembly (EISA process using Pluronic triblock surfactant as soft-template and a phenol-based resin (resol as carbon precursor. These nanocomposites were characterized by X-ray diffraction, nitrogen physisorption and Transmission Electron Microscopy (TEM techniques. Electron tomography (or 3D-TEM technique was particularly useful for providing direct insight on the internal architecture of C/CrN nanocomposite. Nanocomposites showed a very well organized hexagonal mesoporous carbon structure and a relatively high concentration of nanoparticles well distributed in the porous network. The chromium and vanadium nitrides/mesoporous carbon nanocomposites could have many potential applications in catalysis, Li-ion batteries, and supercapacitors.

  12. Multifunctional reactive nanocomposite materials

    Science.gov (United States)

    Stamatis, Demitrios

    Many multifunctional nanocomposite materials have been developed for use in propellants, explosives, pyrotechnics, and reactive structures. These materials exhibit high reaction rates due to their developed reaction interfacial area. Two applications addressed in this work include nanocomposite powders prepared by arrested reactive milling (ARM) for burn rate modifiers and reactive structures. In burn rate modifiers, addition of reactive nanocomposite powders to aluminized propellants increases the burn rate of aluminum and thus the overall reaction rate of an energetic formulation. Replacing only a small fraction of aluminum by 8Al·MoO3 and 2B·Ti nanocomposite powders enhances the reaction rate with little change to the thermodynamic performance of the formulation; both the rate of pressure rise and maximum pressure measured in the constant volume explosion test increase. For reactive structures, nanocomposite powders with bulk compositions of 8Al·MoO3, 12Al·MoO3, and 8Al·3CuO were prepared by ARM and consolidated using a uniaxial die. Consolidated samples had densities greater than 90% of theoretical maximum density while maintaining their high reactivity. Pellets prepared using 8Al·MoO3 powders were ignited by a CO2 laser. Ignition delays increased at lower laser powers and greater pellet densities. A simplified numerical model describing heating and thermal initiation of the reactive pellets predicted adequately the observed effects of both laser power and pellet density on the measured ignition delays. To investigate the reaction mechanisms in nanocomposite thermites, two types of nanocomposite reactive materials with the same bulk compositions 8Al·MoO3 were prepared by different methods. One of the materials was manufactured by ARM and the other, so called metastable interstitial composite (MIC), by mixing of nano-scaled individual powders. Clear differences in the low-temperature redox reactions, welldetectable by differential scanning calorimetry

  13. Highly Thermal Conductive Nanocomposites

    Science.gov (United States)

    Sun, Ya-Ping (Inventor); Connell, John W. (Inventor); Veca, Lucia Monica (Inventor)

    2015-01-01

    Disclosed are methods for forming carbon-based fillers as may be utilized in forming highly thermal conductive nanocomposite materials. Formation methods include treatment of an expanded graphite with an alcohol/water mixture followed by further exfoliation of the graphite to form extremely thin carbon nanosheets that are on the order of between about 2 and about 10 nanometers in thickness. Disclosed carbon nanosheets can be functionalized and/or can be incorporated in nanocomposites with extremely high thermal conductivities. Disclosed methods and materials can prove highly valuable in many technological applications including, for instance, in formation of heat management materials for protective clothing and as may be useful in space exploration or in others that require efficient yet light-weight and flexible thermal management solutions.

  14. Chitin-based Nanocomposites

    Institute of Scientific and Technical Information of China (English)

    D.K.Polyakov; S.N.Chvalun

    2007-01-01

    1 Results The one of the promising development of biodegradable nanocomposites is using native polysaccharides which have pronounced fibril structure to provide not only excellent mechanical properties and biodegradability of produced material but also control the barrier properties, for example increasing selectivity of pervaporation membrane. Chitin is the most popular biopolymer in the nature after cellulose. It is the 2-acetoamido-derivative of cellulose and serves as the fibrous component of the sk...

  15. Nanocomposites and bone regeneration

    Science.gov (United States)

    James, Roshan; Deng, Meng; Laurencin, Cato T.; Kumbar, Sangamesh G.

    2011-12-01

    This manuscript focuses on bone repair/regeneration using tissue engineering strategies, and highlights nanobiotechnology developments leading to novel nanocomposite systems. About 6.5 million fractures occur annually in USA, and about 550,000 of these individual cases required the application of a bone graft. Autogenous and allogenous bone have been most widely used for bone graft based therapies; however, there are significant problems such as donor shortage and risk of infection. Alternatives using synthetic and natural biomaterials have been developed, and some are commercially available for clinical applications requiring bone grafts. However, it remains a great challenge to design an ideal synthetic graft that very closely mimics the bone tissue structurally, and can modulate the desired function in osteoblast and progenitor cell populations. Nanobiomaterials, specifically nanocomposites composed of hydroxyapatite (HA) and/or collagen are extremely promising graft substitutes. The biocomposites can be fabricated to mimic the material composition of native bone tissue, and additionally, when using nano-HA (reduced grain size), one mimics the structural arrangement of native bone. A good understanding of bone biology and structure is critical to development of bone mimicking graft substitutes. HA and collagen exhibit excellent osteoconductive properties which can further modulate the regenerative/healing process following fracture injury. Combining with other polymeric biomaterials will reinforce the mechanical properties thus making the novel nano-HA based composites comparable to human bone. We report on recent studies using nanocomposites that have been fabricated as particles and nanofibers for regeneration of segmental bone defects. The research in nanocomposites, highlight a pivotal role in the future development of an ideal orthopaedic implant device, however further significant advancements are necessary to achieve clinical use.

  16. Metal-Polymer Nanocomposites

    Science.gov (United States)

    Nicolais, Luigi; Carotenuto, Gianfranco

    2004-09-01

    A unique guide to an essential area of nanoscience Interest in nano-sized metals has increased greatly due to their special characteristics and suitability for a number of advanced applications. As technology becomes more refined-including the ability to effectively manipulate and stabilize metals at the nanoscale-these materials present ever-more workable solutions to a growing range of problems. Metal-Polymer Nanocomposites provides the first guide solely devoted to the unique properties and applications of this essential area of nanoscience. It offers a truly multidisciplinary approach, making the text accessible to readers in physical, chemical, and materials science as well as areas such as engineering and topology. The thorough coverage includes: * The chemical and physical properties of nano-sized metals * Different approaches to the synthesis of metal-polymer nanocomposites (MPN) * Advanced characterization techniques and methods for study of MPN * Real-world applications, including color filters, polarizers, optical sensors, nonlinear optical devices, and more * An extensive list of references on the topics covered A unique, cutting-edge resource for a vital area of nanoscience development, Metal-Polymer Nanocomposites is an invaluable text for students and practitioners of materials science, engineering, polymer science, chemical engineering, electrical engineering, and optics.

  17. Heterogeneous nanocomposites of silver selenide and hollow platinum nanoparticles toward methanol oxidation reaction

    Science.gov (United States)

    Cui, Penglei; He, Hongyan; Liu, Hui; Zhang, Suojiang; Yang, Jun

    2016-09-01

    Making use of the electronic coupling between different domains in composite nanomaterials is an effective way to enhance the activity of electrocatalysts. Herein, we demonstrate the preparation of nanocomposites consisting of silver selenide (Ag2Se) and platinum (Pt) nanoparticles with a hollow interior by combining the inside-out diffusion of Ag in core-shell Ag-Pt nanoparticles with the synthesis of highly active hydrophobic Se species. In specific, the Ag2Se-hPt nanocomposites are found to have superior activity and stability for methanol oxidation reaction in an acidic condition due to the strong electronic coupling effect between semiconductor and metal domains. This strategy may provide a greener and less expensive way to the large-scale synthesis of Pt-based nanocomposites, and might be used to generate other heterogeneous nanomaterials with technological importance.

  18. Thermal Aspects Related to Power Assemblies

    Directory of Open Access Journals (Sweden)

    PLESCA, A.

    2010-02-01

    Full Text Available In many cases when a power assembly based on power semiconductors is used, catastrophic failure is the result of steep temperature gradient in the localized temperature distribution. Hence, an optimal heatsink design for certain industrial applications has become a real necessity. In this paper, the Pro/ENGINEER software with the thermal simulation integrated tool, Pro/MECHANICA, has been used for thermal study of a specific power semiconductor assembly. A series of steady-state and transient thermal simulations have been performed. The experimental tests have confirmed the simulation results. Therefore, the use of specific 3D modeling and simulation software allows to design special power semiconductor assemblies with a better thermal transfer between its heatsink and power electronic components at given operating conditions.

  19. Semiconductors bonds and bands

    CERN Document Server

    Ferry, David K

    2013-01-01

    As we settle into this second decade of the twenty-first century, it is evident that the advances in micro-electronics have truly revolutionized our day-to-day lifestyle. The technology is built upon semiconductors, materials in which the band gap has been engineered for special values suitable to the particular application. This book, written specifically for a one semester course for graduate students, provides a thorough understanding of the key solid state physics of semiconductors. It describes how quantum mechanics gives semiconductors unique properties that enabled the micro-electronics revolution, and sustain the ever-growing importance of this revolution.

  20. Physics of semiconductor lasers

    CERN Document Server

    Mroziewicz, B; Nakwaski, W

    2013-01-01

    Written for readers who have some background in solid state physics but do not necessarily possess any knowledge of semiconductor lasers, this book provides a comprehensive and concise account of fundamental semiconductor laser physics, technology and properties. The principles of operation of these lasers are therefore discussed in detail with the interrelations between their design and optical, electrical and thermal properties. The relative merits of a large number of laser structures and their parameters are described to acquaint the reader with the various aspects of the semiconductor l

  1. Defects in semiconductors

    CERN Document Server

    Romano, Lucia; Jagadish, Chennupati

    2015-01-01

    This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoret

  2. Novel fuel cell with nanocomposite functional layer designed by perovskite solar cell principle

    OpenAIRE

    Zhu, Bin; Huang, Yizhong; Fan, L.; Ma, Y.; Wang, Baoyuan; Xia, Chen; Afzal, Muhammad; Zhang, B.; Dong, W; H. Wang; Lund, P. D.

    2016-01-01

    A novel fuel-to-electricity conversion technology resembling a fuel cell has been developed based on the perovskite solar cell principle using a perovskite, e.g. La0.6Sr0.4Co0.2Fe0.8O3-δ and an ionic nanocomposite material as a core functional layer, sandwiched between n- and p-conducting layers. The conversion process makes use of semiconductor energy bands and junctions properties. The physical properties of the junction and alignment of the semiconductor energy band allow for direct ion tr...

  3. Understanding electronic systems in semiconductor quantum dots

    Science.gov (United States)

    Ciftja, Orion

    2013-11-01

    Systems of confined electrons are found everywhere in nature in the form of atoms where the orbiting electrons are confined by the Coulomb attraction of the nucleus. Advancement of nanotechnology has, however, provided us with an alternative way to confine electrons by using artificial confining potentials. A typical structure of this nature is the quantum dot, a nanoscale system which consists of few confined electrons. There are many types of quantum dots ranging from self-assembled to miniaturized semiconductor quantum dots. In this work we are interested in electrostatically confined semiconductor quantum dot systems where the electrostatic confining potential that traps the electrons is generated by external electrodes, doping, strain or other factors. A large number of semiconductor quantum dots of this type are fabricated by applying lithographically patterned gate electrodes or by etching on two-dimensional electron gases in semiconductor heterostructures. Because of this, the whole structure can be treated as a confined two-dimensional electron system. Quantum confinement profoundly affects the way in which electrons interact with each other, and external parameters such as a magnetic field. Since a magnetic field affects both the orbital and the spin motion of the electrons, the interplay between quantum confinement, electron-electron correlation effects and the magnetic field gives rise to very interesting physical phenomena. Thus, confined systems of electrons in a semiconductor quantum dot represent a unique opportunity to study fundamental quantum theories in a controllable atomic-like setup. In this work, we describe some common theoretical models which are used to study confined systems of electrons in a two-dimensional semiconductor quantum dot. The main emphasis of the work is to draw attention to important physical phenomena that arise in confined two-dimensional electron systems under various quantum regimes.

  4. 基于自组装原位生长法制备聚苯胺/CNTs纳米复合物修饰叉指电极的葡萄糖生物传感器%Glucose biosensor based on self assembled-in situ polymerized polyaniline/CNTs nanocomposite modified interdigitalelectrode

    Institute of Scientific and Technical Information of China (English)

    孙建东; 马振华; 姚晓霞; 赵修青; 李海涛; 王建伟; 柴秀琴; 王会才

    2015-01-01

    采用自组装原位生长制备基于聚苯胺/CNTs纳米复合物修饰叉指电极的葡萄糖生物传感器.首先采用自组装的方式制备CNTs修饰叉指电极,并采用对甲苯磺酸掺杂聚苯胺,原位在修饰电极表面生长聚苯胺,制备了PANI/CNTs修饰电极;然后将葡萄糖氧化酶固定在修饰电极表面制备了葡萄糖生物传感器.采用拉曼光谱、扫描电子显微镜、原子力显微镜等对所制备的PANI/CNTs复合物进行了表征分析;采用循环伏安法和电化学阻抗法研究了修饰电极的电化学行为.传感器性能评价结果表明:在最优化条件下,葡萄糖浓度与响应电流在0.5~30 mmol/L范围内呈现良好的线性关系,响应灵敏度为62.17μA/(mmol·L-1),线性相关系数为0.997,检出限为0.15 mmol/L(S/N=3),并具有良好的重现性和稳定性.%Glucose biosensors based on self assembled-in situ polymerized polyaniline /CNTs nanocomposite modified interdigitalelectrode were prepared. Firstly, CNTs modified interdigital electrode was prepared by self assembling process, and PANI/CNTs was prepared using p-toluene sulfonic acid doped polyaniline in situ polymerized aniline on the electrode surface;then glucose biosensor was prepared by immobilization of glucose oxidase on the as prepared modified electrode surface. The PANI/CNTs nanocomposites were characterized by Raman spectra analysis, scanning electron microscopy and atomic force microscopy;electrochemical behaviors of the modified electrode were characterized by cyclic voltammetry and electrochemical impedance method. The results showed that under the optimum conditions, glucose concentration and the response current showed a good linear relationship in the range of 0.5-30 mmol/L with the response sensitivity of 62.17 μA/(mmol·L-1), the linear correlation coefficient of 0.997, and the detection limit of 0.15 mmol/L (S/N=3). The biosensor also showed good stability and reproducibility.

  5. Polyacrolein/mesoporous silica nanocomposite: Synthesis, thermal stability and covalent lipase immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Motevalizadeh, Seyed Farshad; Khoobi, Mehdi; Shabanian, Meisam [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 14176 (Iran, Islamic Republic of); Asadgol, Zahra; Faramarzi, Mohammad Ali [Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran 14176 (Iran, Islamic Republic of); Shafiee, Abbas, E-mail: ashafiee@ams.ac.ir [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 14176 (Iran, Islamic Republic of); Center of Excellence in Biothermodynamics, University of Tehran, Tehran (Iran, Islamic Republic of)

    2013-12-16

    In this work, new polyacrolein/MCM-41 nanocomposites with good phase mixing behavior were prepared through an emulsion polymerization technique. Mesoporous silica was synthesized by in situ assembly of tetraethyl orthosilicate (TEOS) and cetyl trimethyl ammonium bromide (CTAB). The structure and properties of polyacrolein containing nanosized MCM-41 particle (5 and 10 wt%), were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, Dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N{sub 2} adsorption techniques, and thermogravimetric (TGA) analyses. The SEM images from the final powder have revealed good dispersion of the MCM-41 nanoparticles throughout polymeric matrix with no distinct voids between two phases. The results indicated that the thermal properties of the nanocomposite were enhanced by addition of MCM-41. Thermomyces lanuginosa lipase (TLL) was used as a model biocatalyst and successfully immobilized with polyacrolein and the nanocomposite via covalent bonds with the aldehyde groups. The activity between free enzyme, polyacrolein, and MCM-41 nanocomposite (10 wt%)-immobilized TLL was compared. The immobilized lipase with the nanocomposite shows better operational stability such as pH tolerance, thermal and storage stability. In addition, the immobilized lipase with the nanocomposite can be easily recovered and retained at 74% of its initial activity after 15 time reuses. - Graphical abstract: The influence of incorporation of mesoporous MCM-41 nanoparticle with polyacrolein on the thermal properties and enzyme immobilization was investigated. - Highlights: • Polyacrolein/MCM-41 nanocomposites were prepared by emulsion polymerization method. • Thermal stability and char residues in nanocomposites were improved. • Nanocomposites significant effects on immobilization of lipase.

  6. Polyacrolein/mesoporous silica nanocomposite: Synthesis, thermal stability and covalent lipase immobilization

    International Nuclear Information System (INIS)

    In this work, new polyacrolein/MCM-41 nanocomposites with good phase mixing behavior were prepared through an emulsion polymerization technique. Mesoporous silica was synthesized by in situ assembly of tetraethyl orthosilicate (TEOS) and cetyl trimethyl ammonium bromide (CTAB). The structure and properties of polyacrolein containing nanosized MCM-41 particle (5 and 10 wt%), were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, Dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption techniques, and thermogravimetric (TGA) analyses. The SEM images from the final powder have revealed good dispersion of the MCM-41 nanoparticles throughout polymeric matrix with no distinct voids between two phases. The results indicated that the thermal properties of the nanocomposite were enhanced by addition of MCM-41. Thermomyces lanuginosa lipase (TLL) was used as a model biocatalyst and successfully immobilized with polyacrolein and the nanocomposite via covalent bonds with the aldehyde groups. The activity between free enzyme, polyacrolein, and MCM-41 nanocomposite (10 wt%)-immobilized TLL was compared. The immobilized lipase with the nanocomposite shows better operational stability such as pH tolerance, thermal and storage stability. In addition, the immobilized lipase with the nanocomposite can be easily recovered and retained at 74% of its initial activity after 15 time reuses. - Graphical abstract: The influence of incorporation of mesoporous MCM-41 nanoparticle with polyacrolein on the thermal properties and enzyme immobilization was investigated. - Highlights: • Polyacrolein/MCM-41 nanocomposites were prepared by emulsion polymerization method. • Thermal stability and char residues in nanocomposites were improved. • Nanocomposites significant effects on immobilization of lipase

  7. Hyperbolic metamaterials based on quantum-dot plasmon-resonator nanocomposites

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Ozel, T.; Mutlugun, E.;

    2014-01-01

    We theoretically demonstrate that nanocomposites made of colloidal semiconductor quantum dot monolayers placed between metal nanoparticle monolayers can function as multilayer hyperbolic metamaterials. Depending on the thickness of the spacer between the quantum dot and nanoparticle layers...... metamaterials are capable of increasing the radiative decay rate of emission centers inside them. The proposed theoretical framework can also be used to design quantum-dot/nanoplasmonic composites with optimized luminescence enhancement....

  8. Development of fluorescent nanocomposites based on CdTe quantum dots

    OpenAIRE

    Oliveira, Vanessa; Moura, I; Machado, A.V.

    2015-01-01

    Cadmium telluride (CdTe) quantum dots (QDs) are efficient fluorescence semiconductor nanoparticles with unique optical and physicochemical properties. Their incorporation into polymer matrices allows the development of materials with several applications such as in opto-eletronic devices. Nevertheless, one of the most important prerequisite of these high-efficiency nanocomposites is the fluorescence efficiency of the QDs– polymer, which is mainly related with the QDs...

  9. Physics of semiconductor devices

    CERN Document Server

    Rudan, Massimo

    2015-01-01

    This book describes the basic physics of semiconductors, including the hierarchy of transport models, and connects the theory with the functioning of actual semiconductor devices.  Details are worked out carefully and derived from the basic physics, while keeping the internal coherence of the concepts and explaining various levels of approximation. Examples are based on silicon due to its industrial importance. Several chapters are included that provide the reader with the quantum-mechanical concepts necessary for understanding the transport properties of crystals. The behavior of crystals incorporating a position-dependent impurity distribution is described, and the different hierarchical transport models for semiconductor devices are derived (from the Boltzmann transport equation to the hydrodynamic and drift-diffusion models). The transport models are then applied to a detailed description of the main semiconductor-device architectures (bipolar, MOS). The final chapters are devoted to the description of s...

  10. Electrowetting on a semiconductor

    CERN Document Server

    Arscott, Steve

    2012-01-01

    We report electrowetting on a semiconductor using of a mercury droplet resting on a silicon surface. The effect is demonstrated using commercial n-type and p-type single-crystal (100) silicon wafers of different doping levels. The electrowetting is reversible - the voltage-dependent wetting contact angle variation of the mercury droplet is observed to depend on both the underlying semiconductor doping density and type. The electrowetting behaviour is explained by the voltage-dependent modulation of the space-charge capacitance at the metal-semiconductor junction - current-voltage and capacitance-voltage-frequency measurements indicate this to be the case. A model combining the metal-semiconductor junction capacitance and the Young-Lippmann electrowetting equation agrees well with the observations.

  11. Compact semiconductor lasers

    CERN Document Server

    Yu, Siyuan; Lourtioz, Jean-Michel

    2014-01-01

    This book brings together in a single volume a unique contribution by the top experts around the world in the field of compact semiconductor lasers to provide a comprehensive description and analysis of the current status as well as future directions in the field of micro- and nano-scale semiconductor lasers. It is organized according to the various forms of micro- or nano-laser cavity configurations with each chapter discussing key technical issues, including semiconductor carrier recombination processes and optical gain dynamics, photonic confinement behavior and output coupling mechanisms, carrier transport considerations relevant to the injection process, and emission mode control. Required reading for those working in and researching the area of semiconductors lasers and micro-electronics.

  12. Defects in semiconductor nanostructures

    Indian Academy of Sciences (India)

    Vijay A Singh; Manoj K Harbola; Praveen Pathak

    2008-02-01

    Impurities play a pivotal role in semiconductors. One part in a million of phosphorous in silicon alters the conductivity of the latter by several orders of magnitude. Indeed, the information age is possible only because of the unique role of shallow impurities in semiconductors. Although work in semiconductor nanostructures (SN) has been in progress for the past two decades, the role of impurities in them has been only sketchily studied. We outline theoretical approaches to the electronic structure of shallow impurities in SN and discuss their limitations. We find that shallow levels undergo a SHADES (SHAllow-DEep-Shallow) transition as the SN size is decreased. This occurs because of the combined effect of quantum confinement and reduced dielectric constant in SN. Level splitting is pronounced and this can perhaps be probed by ESR and ENDOR techniques. Finally, we suggest that a perusal of literature on (semiconductor) cluster calculations carried out 30 years ago would be useful.

  13. Biggest semiconductor installed

    CERN Multimedia

    2008-01-01

    Scientists and technicians at the European Laboratory for Particle Physics, commonly known by its French acronym CERN (Centre Europen pour la Recherche Nuclaire), have completed the installation of the largest semiconductor silicon detector.

  14. Isotopically controlled semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Haller, E.E.

    2004-11-15

    A review of recent research involving isotopically controlled semiconductors is presented. Studies with isotopically enriched semiconductor structures experienced a dramatic expansion at the end of the Cold War when significant quantities of enriched isotopes of elements forming semiconductors became available for worldwide collaborations. Isotopes of an element differ in nuclear mass, may have different nuclear spins and undergo different nuclear reactions. Among the latter, the capture of thermal neutrons which can lead to neutron transmutation doping, can be considered the most important one for semiconductors. Experimental and theoretical research exploiting the differences in all the properties has been conducted and will be illustrated with selected examples. Manuel Cardona, the longtime editor-in-chief of Solid State Communications has been and continues to be one of the major contributors to this field of solid state physics and it is a great pleasure to dedicate this review to him.

  15. A semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Naoko, O.; Masaru, K.

    1984-04-20

    A semiconductor laser with enhanced characteristics is patented in which bleaching coatings are generated on the outcoupling mirrors by sputtering alternating coating layers made from A1203 and A10, with high and low indices of refraction.

  16. Photocatalytic studies of Ag/ZnO nanocomposite particles produced via ultrasonic spray pyrolysis method

    Energy Technology Data Exchange (ETDEWEB)

    Dermenci, Kamil Burak [Dept. of Materials Science and Engineering, Anadolu University, Eskisehir (Turkey); Dept. of Metallurgical and Materials Engineering, Istanbul Technical University, Istanbul (Turkey); Genc, Bora [Dept. of Environmental Engineering, Istanbul Technical University, Istanbul (Turkey); Ebin, Burçak [Dept. of Metallurgical and Materials Engineering, Istanbul Technical University, Istanbul (Turkey); Olmez-Hanci, Tugba [Dept. of Environmental Engineering, Istanbul Technical University, Istanbul (Turkey); Gürmen, Sebahattin, E-mail: gurmen@itu.edu.tr [Dept. of Metallurgical and Materials Engineering, Istanbul Technical University, Istanbul (Turkey)

    2014-02-15

    Highlights: • Ag/ZnO nanocomposite catalyst with a single step route is synthesized. • Methylene Blue decolorization, degradation and first order kinetics is studied. • The highest decolorization and degradation rates are 40% and 27% respectively. • The highest degradation rate coefficient is 9 × 10{sup −3} min{sup −1}. • Crystallite sizes and atomic fraction difference are important parameters. -- Abstract: Noble metal/semiconductor oxide nanocomposites have considerable interest on degradation of pollutants from textile wastewaters. Ag/ZnO, as one of the noble metal/semiconductor oxide nanocomposite, is highly efficient catalyst in textile pollutant degradation that allows irradiation wavelength towards visible light region. Ultrasonic spray pyrolysis method was used to produce spherical, homogenously distributed and submicron Ag/ZnO nanocomposite particles in one step. A water leach solution (0.05–0.2 M, Ag{sup +}:Zn{sup 2+} = 1:1) is carried by non-cost air into the reaction furnace (T = 700 °C, 800 °C and 900 °C). UV-A illumination of Methylene Blue (MB) with the presence of Ag/ZnO nanocatalysts after 60 min results up to 40% MB decolorization, 9 × 10{sup −3} min{sup −1} decolorization rate constant.

  17. VECSEL Semiconductor Lasers

    Institute of Scientific and Technical Information of China (English)

    SHANXiao-nan; LUGuo-guang; HEChun-feng; SUNYan-fang; LITe; QINLi; NINGYong-qiang; WANGLi-jun

    2005-01-01

    Surface-emitting semiconductor lasers can make use of external cavities and optical pumping techniques to achieve a combination of high continuous-wave output power and near-diffraction-limited beam quality that is not matched by any other type of semiconductor source. The ready access to the laser mode that the external cavity provides has been exploited for applications such as intra-cavity frequency doubling and passive mode-locking.

  18. Radiation effects in semiconductors

    CERN Document Server

    2011-01-01

    There is a need to understand and combat potential radiation damage problems in semiconductor devices and circuits. Written by international experts, this book explains the effects of radiation on semiconductor devices, radiation detectors, and electronic devices and components. These contributors explore emerging applications, detector technologies, circuit design techniques, new materials, and innovative system approaches. The text focuses on how the technology is being used rather than the mathematical foundations behind it. It covers CMOS radiation-tolerant circuit implementations, CMOS pr

  19. Electronic properties of semiconductor heterostructures

    International Nuclear Information System (INIS)

    Ten papers on the electronic properties of semiconductors and semiconductor heterostructures constitute the backbone of this thesis. Four papers address the form and validity of the single-band effective mass approximation for semiconductor heterostructures. In four other papers properties of acceptor states in bulk semiconductors and semiconductor heterostructures are studied using the novel effective bond-orbital model. The last two papers deal with localized excitions. 122 refs

  20. Synthesis of nanocomposites using glasses and mica as templates

    Indian Academy of Sciences (India)

    D Chakravorty; S Basu; B N Pal; P K Mukherjee; B Ghosh; K Chatterjee; A Bose; S Bhattacharya; A Banerjee

    2008-06-01

    Various nanocomposites were synthesized using either a silica-based glass or mica crystallites as the medium. In some cases by an oxidation or a sulfidation treatment a core-shell nanostructure could be generated. Iron–iron oxide core-shell structured nanocomposites exhibited excellent humidity sensing behaviour. Gold–gold sulfide core-shell nanorods exhibited a number of optical absorption peaks which arose because of their structural characteristics. Nanoparticles of silver and silver oxide could be aligned in a polymethylmethacrylate film by an a.c. electric field of 1 MHz frequency. The composites showed large sensitivity to relative humidity. Lead sulfide nanowires of diameter, 1.2 nm, were grown within the nanochannels of Na-4 mica. These exhibited a semiconductor to metal transition at around 300 K. This arose because of high pressure generated on the nanowires. Copper sulfide nanowires grown within the Na-4 mica channels showed metallic behaviour. Silver core–silver orthosilicate shell nanostructures developed within a silicate glass medium showed discontinuous changes in resistivity at some specific temperatures. This was explained as arising due to excitation of Lamb modes at certain pressures generated because of thermal expansion mismatch of the core and the shell phases. Optical properties of iron core–iron oxide shell nanocomposites when analysed by effective medium theory led to the result of a metal non-metal transition for particle diameters below a critical value. Similar results were obtained from optical absorption data of silver nanoparticles grown in a tetrapeptide solution.

  1. Additive manufacturing approaches for stress relief in semiconductor die packaging

    NARCIS (Netherlands)

    Zon, C.M.B. van der; Wiel, A. van der; Maalderink, H.H.; Vaes, M.H.E.; Aulbers, A.P.; Vorst, L.T.G. van de; Cate, A.T. ten; Furrer, J.F.; Burssens, J.W.; Chen, J.

    2012-01-01

    Packaging of semiconductor chips, especially MEMS-based, always causes stress on the functional areas of the die causing unpredictable changes in chip performance. As a consequence such devices can only be calibrated individually after complete assembly. Melexis and TNO have developed an approach to

  2. An introduction to polymer nanocomposites

    International Nuclear Information System (INIS)

    This review presents an overview of the formulation, characterization and range of applications for polymer nanocomposites. After explaining how material properties at the nanometre scale can vary compared to those observed at longer length scales, typical methods used to formulate and characterize nanocomposites at laboratory and industrial scale will be described. The range of mechanical, electrical and thermal properties obtainable from nanocomposite materials, with examples of current commercial applications, will be outlined. Formulation and characterization of nanoparticle, nanotube and graphene composites will be discussed by reference to nanoclay-based composites, as the latter are presently of most technological relevance. Three brief case studies are presented to demonstrate how structure/property relationships may be controlled in a variety of polymer nanocomposite systems to achieve required performance in a given application. The review will conclude by discussing potential obstacles to commercial uptake of polymer nanocomposites, such as inconsistent protocols to characterize nanocomposites, cost/performance balances, raw material availability, and emerging legislation, and will conclude by discussing the outlook for future development and commercial uptake of polymer nanocomposites. (review)

  3. Polymer nanocomposites reinforced with montmorillonite

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2012-01-01

    Full Text Available Purpose: Light microscope with polarized light has been used for observation layered zone, visible thanks to polarization of the light, inside polymer-polymer composites and nanocomposites Aim of work has been concentrated on investigation of nanocomposites as promising engineering materials, basing on composition of polypropylene and montmorillonite as reinforcement in the shape of nanoparticles of 2:1 silicate.Design/methodology/approach: Conventional and non-conventional injection molding process has been used for obtaining nanocomposites. In non-conventional process has been used the special mold for inducing the shear rates, additionally equipped with external computer to control melt manipulation of solidifying polymer inside mold cavityFindings: Highly developed structure consisted of multilayer zone between skin and core mainly responsible for reinforcement and improvement of fracture toughness of polymer composites and nanocompositesResearch limitations/implications: Nanocomposites of polymer blends and montmorillonite were moulded by direct injection moulding according to melt temperature and stroke time-number combination included in design of experiments.Practical implications: Application of special injection moulding technique provides to structure development and gives possibility to create multilayer zone, which strengthen material. Besides strengthening obtaining of such nanocomposites is cheap thanks to application of low cost injection moulding technique and not expensive polyolefines with developed structure, without using additional fillers (e.g. compatybilizers.Originality/value: Very wide application of polymer composites and nanocomposites as engineering materials used for various industries like building engineering, automotive and aerospace

  4. Synthesis, characterization and low temperature electrical conductivity of Polyaniline/NiFe2O4 nanocomposites

    Science.gov (United States)

    Prasanna, G. D.; Prasad, V. B.; Jayanna, H. S.

    2015-02-01

    Conducting polymer/ferrite nanocomposites with an organized structure provide a new functional hybrid between organic and inorganic materials. The most popular among the conductive polymers is the polyaniline (PANI) due to its wide application in different fields. In the present work nickel ferrite (NiFe2O4) nanoparticles were prepared by sol-gel citrate-nitrate method with an average size of 21.6nm. PANI/NiFe2O4 nanoparticles were synthesized by a simple general and inexpensive in-situ polymerization in the presence of NiFe2O4 nanoparticles. The effects of NiFe2O4 nanoparticles on the dc-electrical properties of polyaniline were investigated. The structural components in the nanocomposites were identified from Fourier Transform Infrared (FTIR) spectroscopy. The crystalline phase of nanocomposites was characterized by X-Ray Diffraction (XRD). The Scanning Electron Micrograph (SEM) reveals that there was some interaction between the NiFe2O4 particles and polyaniline and the nanocomposites are composed of polycrystalline ferrite nanoparticles and PANI. The dc conductivity of polyaniline/NiFe2O4 nanocomposites have been measured as a function of temperature in the range of 80K to 300K. It is observed that the room temperature conductivity cRT decreases with increase in the relative content of NiFe2O4. The experimental data reveals that the resistivity increases for all composites with decrease of temperature exhibiting semiconductor behaviour.

  5. Method of doping a semiconductor

    Science.gov (United States)

    Yang, Chiang Y.; Rapp, Robert A.

    1983-01-01

    A method for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient.

  6. Mechanical properties and cytotoxicity of nanoplate-like hydroxyapatite/polylactide nanocomposites prepared by intercalation technique.

    Science.gov (United States)

    Wan, Yizao; Wu, Chaoqun; Xiong, Guangyao; Zuo, Guifu; Jin, Jun; Ren, Kaijing; Zhu, Yong; Wang, Zheren; Luo, Honglin

    2015-07-01

    Hydroxyapatite (HAp) in the forms of fiber, needle, and whisker has been employed as fillers in polymer composites. Herein, nanoplate-like HAp synthesized by template-assisted self-assembly was used to reinforce polylactide (PLA) nanocomposites via the solution intercalation method. Dynamic and static mechanical properties and cytotoxicity of the as-prepared HAp/PLA nanocomposites were assessed in addition to characterizations by XRD, FTIR, and TGA. XRD analysis confirms the formation of exfoliated structure in the HAp/PLA nanocomposites. The HAp/PLA nanocomposites exhibit better static and dynamic mechanical properties than unreinforced PLA. Furthermore, the HAp/PLA nanocomposite with an optimum HAp content of 20wt% (20HAp/PLA) demonstrates not only the best mechanical performance but also the highest thermal stability among the nanocomposite samples. Cell studies using a mouse fibroblast cell line (L929) suggest that 20HAp/PLA shows excellent biocompatibility, which makes it a promising material for biomedical applications. PMID:25837342

  7. Photocatalytic and antibacterial activity of cadmium sulphide/zinc oxide nanocomposite with varied morphology.

    Science.gov (United States)

    Jana, T K; Maji, S K; Pal, A; Maiti, R P; Dolai, T K; Chatterjee, K

    2016-10-15

    Nanocomposites with multifunctional application prospects have already dragged accelerating interests of materials scientists. Here we present CdS/ZnO nanocomposites with different morphology engineering the precursor molar ratio in a facile wet chemical synthesis route. The materials were structurally and morphologically characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX) and high-resolution transmission electron microscopy (HRTEM). The growth mechanism of the composite structure with varying molar ratio is delineated with oriented attachment self assemble techniques. Photocatalytic activity of CdS/ZnO nanocomposites with varying morphology were explored for the degradation of rhodamine B (RhB) dye in presence of visible light irradiation and the results reveal that the best catalytic performance arises in CdS/ZnO composite with 1: 1 ratio. The antibacterial efficiency of all nanocomposites were investigated on Escherichia coli, Staphylococcus aureus and Klebsiella pneumonia without light irradiation. Antibacterial activity of CdS/ZnO nanocomposites were studied using the bacteriological test-well diffusion agar method and results showed significant antibacterial activity in CdS/ZnO composite with 1:3 ratio. Overall, CdS/ZnO nanocomposites excel in different potential applications, such as visible light photocatalysis and antimicrobial activity with their tuneable structure. PMID:27399614

  8. Photoinduced superconductivity in semiconductors

    Science.gov (United States)

    Goldstein, Garry; Aron, Camille; Chamon, Claudio

    2015-02-01

    We show that optically pumped semiconductors can exhibit superconductivity. We illustrate this phenomenon in the case of a two-band semiconductor tunnel-coupled to broad-band reservoirs and driven by a continuous wave laser. More realistically, we also show that superconductivity can be induced in a two-band semiconductor interacting with a broad-spectrum light source. We furthermore discuss the case of a three-band model in which the middle band replaces the broad-band reservoirs as the source of dissipation. In all three cases, we derive the simple conditions on the band structure, electron-electron interaction, and hybridization to the reservoirs that enable superconductivity. We compute the finite superconducting pairing and argue that the mechanism can be induced through both attractive and repulsive interactions and is robust to high temperatures.

  9. Fundamentals of semiconductor lasers

    CERN Document Server

    Numai, Takahiro

    2015-01-01

    This book explains physics under the operating principles of semiconductor lasers in detail based on the experience of the author, dealing with the first manufacturing of phase-shifted DFB-LDs and recent research on transverse modes.   The book also bridges a wide gap between journal papers and textbooks, requiring only an undergraduate-level knowledge of electromagnetism and quantum mechanics, and helps readers to understand journal papers where definitions of some technical terms vary, depending on the paper. Two definitions of the photon density in the rate equations and two definitions of the phase-shift in the phase-shifted DFB-LD are explained, and differences in the calculated results are indicated, depending on the definitions.    Readers can understand the physics of semiconductor lasers and analytical tools for Fabry-Perot LDs, DFB-LDs, and VCSELs and will be stimulated to develop semiconductor lasers themselves.

  10. Sonochemical Preparation of Polymer Nanocomposites

    Directory of Open Access Journals (Sweden)

    Hyoung Jin Choi

    2009-06-01

    Full Text Available Thisreview covers sonochemical fabrication of polymer nanocomposites. In addition to its application to the synthesis of various polymeric systems, due to its powerful efficiency, sonochemistry has been widely used not only as the assistant of dispersion for nanomaterials such as carbon nanotubes (CNT and organophillic clay, but also as a special initiator to enhance polymerization for fabrication of polymer nanocomposites with CNT and metallic nanoparticles. Recent developments in the preparation of multi-walled carbon nanotube/polymer nanocomposites with polystyrene and PMMA, magnetic particle/CNT composites and polymer/clay nanocomposites along with their physical characteristics and potential engineering applications will be introduced. Physical characterizations include morphological, thermal, and rheological properties under either an applied electric or magnetic field.

  11. Magnetoelectric Nanocomposites for Flexible Electronics

    KAUST Repository

    Al-Nassar, Mohammed Y.

    2015-09-01

    Flexibility, low cost, versatility, miniaturization and multi-functionality are key aspects driving research and innovation in many branches of the electronics industry. With many anticipated emerging applications, like wearable, transparent and biocompatible devices, interest among the research community in pursuit for novel multifunctional miniaturized materials have been amplified. In this context, multiferroic polymer-based nanocomposites, possessing both ferroelectricity and ferromagnetism, are highly appealing. Most importantly, these nanocomposites possess tunable ferroelectric and ferromagnetic properties based on the parameters of their constituent materials as well as the magnetoelectric effect, which is the coupling between electric and magnetic properties. This tunability and interaction is a fascinating fundamental research field promising tremendous potential applications in sensors, actuators, data storage and energy harvesting. This dissertation work is devoted to the investigation of a new class of multiferroic polymer-based flexible nanocomposites, which exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature, with the goal of understanding and optimizing the origin of their magnetoelectric coupling. The nanocomposites consist of high aspect ratio ferromagnetic nanowires (NWs) embedded inside a ferroelectric co-polymer, poly(vinylindene fluoride-trifluoroethylene), P(VDF-TrFE) matrix. First, electrochemical deposition of ferromagnetic NWs inside anodic aluminum oxide membranes is discussed. Characterization of electrodeposited iron, nickel and highly magnetostrictive iron-gallium alloy NWs was done using XRD, electron and magnetic force microscopy. Second, different nanocomposite films have been fabricated by means of spin coating and drop casting techniques. The effect of incorporation of NWs inside the ferroelectric polymer on its electroactive phase is discussed. The remanent and saturation polarization as well

  12. Polymer nanocomposites reinforced with montmorillonite

    OpenAIRE

    L.A. Dobrzański; M. Bilewicz; Viana, J. C.

    2012-01-01

    Purpose: Light microscope with polarized light has been used for observation layered zone, visible thanks to polarization of the light, inside polymer-polymer composites and nanocomposites Aim of work has been concentrated on investigation of nanocomposites as promising engineering materials, basing on composition of polypropylene and montmorillonite as reinforcement in the shape of nanoparticles of 2:1 silicate.Design/methodology/approach: Conventional and non-conventional injection molding ...

  13. Advances in semiconductor lasers

    CERN Document Server

    Coleman, James J; Jagadish, Chennupati

    2012-01-01

    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scien

  14. Introductory semiconductor device physics

    CERN Document Server

    Parker, Greg

    2004-01-01

    ATOMS AND BONDINGThe Periodic TableIonic BondingCovalent BondingMetallic bondingvan der Waals BondingStart a DatabaseENERGY BANDS AND EFFECTIVE MASSSemiconductors, Insulators and MetalsSemiconductorsInsulatorsMetalsThe Concept of Effective MassCARRIER CONCENTRATIONS IN SEMICONDUCTORSDonors and AcceptorsFermi-LevelCarrier Concentration EquationsDonors and Acceptors Both PresentCONDUCTION IN SEMICONDUCTORSCarrier DriftCarrier MobilitySaturated Drift VelocityMobility Variation with TemperatureA Derivation of Ohm's LawDrift Current EquationsSemiconductor Band Diagrams with an Electric Field Presen

  15. Ternary chalcopyrite semiconductors

    CERN Document Server

    Shay, J L; Pamplin, B R

    2013-01-01

    Ternary Chalcopyrite Semiconductors: Growth, Electronic Properties, and Applications covers the developments of work in the I-III-VI2 and II-IV-V2 ternary chalcopyrite compounds. This book is composed of eight chapters that focus on the crystal growth, characterization, and applications of these compounds to optical communications systems. After briefly dealing with the status of ternary chalcopyrite compounds, this book goes on describing the crystal growth of II-IV-V2 and I-III-VI2 single crystals. Chapters 3 and 4 examine the energy band structure of these semiconductor compounds, illustrat

  16. XAFS applications in semiconductors

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    X-ray absorption fine structure (XAFS) has experienced a rapid development in the last three decades and has proven to be a powerful structural characterization technique nowadays. In this review, the XAFS basic principles including the theory, the data analysis, and the experiments have been introduced in detail. To show its strength as a local structure probe, the XAFS applications in semiconductors are summarized comprehensively, that is, thin films,quantum wells and dots, dilute magnetic semiconductors, and so on. In addition, certain new XAFS-related techniques,such as in-situ XAFS, micro-XAFS, and time-resolved XAFS are also shown.

  17. METAL-SEMICONDUCTOR JUNCTIONS

    OpenAIRE

    Flores, F.; Sánchez-Dehesa, J.; Guinea, F.

    1984-01-01

    In spite of many different models there seems to be a general lack of understanding about the mechanism of Schottky barrier formation. In order to elucidate this mechanism for covalent semiconductors, we present theoretical selfconsistent calculations for abrupt Si-Ag, C-Ag and Si-H-Ag junctions. Our results are in good agreement with the available experimental evidence, and show that the interface Fermi level is controlled by a density of states that appears in the semiconductor gap as a res...

  18. Compound semiconductor device physics

    CERN Document Server

    Tiwari, Sandip

    2013-01-01

    This book provides one of the most rigorous treatments of compound semiconductor device physics yet published. A complete understanding of modern devices requires a working knowledge of low-dimensional physics, the use of statistical methods, and the use of one-, two-, and three-dimensional analytical and numerical analysis techniques. With its systematic and detailed**discussion of these topics, this book is ideal for both the researcher and the student. Although the emphasis of this text is on compound semiconductor devices, many of the principles discussed will also be useful to those inter

  19. Semiconductor opto-electronics

    CERN Document Server

    Moss, TS; Ellis, B

    1972-01-01

    Semiconductor Opto-Electronics focuses on opto-electronics, covering the basic physical phenomena and device behavior that arise from the interaction between electromagnetic radiation and electrons in a solid. The first nine chapters of this book are devoted to theoretical topics, discussing the interaction of electromagnetic waves with solids, dispersion theory and absorption processes, magneto-optical effects, and non-linear phenomena. Theories of photo-effects and photo-detectors are treated in detail, including the theories of radiation generation and the behavior of semiconductor lasers a

  20. Coherent dynamics in semiconductors

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher

    1998-01-01

    enhanced in quantum confined lower-dimensional systems, where exciton and biexciton effects dominate the spectra even at room temperature. The coherent dynamics of excitons are at modest densities well described by the optical Bloch equations and a number of the dynamical effects known from atomic...... and molecular systems are found and studied in the exciton-biexciton system of semiconductors. At densities where strong exciton interactions, or many-body effects, become dominant, the semiconductor Bloch equations present a more rigorous treatment of the phenomena Ultrafast degenerate four-wave mixing is used...

  1. Engineering magnetism in semiconductors

    Directory of Open Access Journals (Sweden)

    Tomasz Dietl

    2006-11-01

    Full Text Available Transition metal doped III-V, II-VI, and group IV compounds offer an unprecedented opportunity to explore ferromagnetism in semiconductors. Because ferromagnetic spin-spin interactions are mediated by holes in the valence band, changing the Fermi level using co-doping, electric fields, or light can directly manipulate the magnetic ordering. Moreover, engineering the Fermi level position by co-doping makes it possible to modify solubility and self-compensation limits, affecting magnetic characteristics in a number of surprising ways. The Fermi energy can even control the aggregation of magnetic ions, providing a new route to self-organization of magnetic nanostructures in a semiconductor host.

  2. Semiconductor surface protection material

    Science.gov (United States)

    Packard, R. D. (Inventor)

    1973-01-01

    A method and a product for protecting semiconductor surfaces is disclosed. The protective coating material is prepared by heating a suitable protective resin with an organic solvent which is solid at room temperature and converting the resulting solution into sheets by a conventional casting operation. Pieces of such sheets of suitable shape and thickness are placed on the semiconductor areas to be coated and heat and vacuum are then applied to melt the sheet and to drive off the solvent and cure the resin. A uniform adherent coating, free of bubbles and other defects, is thus obtained exactly where it is desired.

  3. A special section on semiconductors

    Institute of Scientific and Technical Information of China (English)

    Mingwang SHAO

    2011-01-01

    @@ Semiconductors are inherently endowed with excellent photoelectric properties.Semiconductor materials are the foundation of modern electronics and many other devices including transistors, solar cells, many kinds of diodes,and digital and analog integrated circuits.

  4. Self-assembled hybrid materials based on conjugated polymers and semiconductors nano-crystals for plastic solar cells; Architectures hybrides auto-assemblees a base de systemes polyconjugues et de nanocristaux de semi-conducteurs pour le photovoltaique plastique

    Energy Technology Data Exchange (ETDEWEB)

    Girolamo, J. de

    2007-11-15

    This work is devoted to the elaboration of self-assembled hybrid materials based on poly(3- hexyl-thiophene) and CdSe nano-crystals for photovoltaic applications. For that, complementary molecular recognition units were introduced as side chain groups on the polymer and at the nano-crystals' surface. Diamino-pyrimidine groups were introduced by post-functionalization of a precursor copolymer, namely poly(3-hexyl-thiophene-co-3- bromo-hexyl-thiophene) whereas thymine groups were introduced at the nano-crystals' surface by a ligand exchange reaction with 1-(6-mercapto-hexyl)thymine. However, due to their different solubility, the mixing of the two components by solution processes is difficult. A 'one-pot' procedure was developed, but this method led to insoluble aggregates without control of the hybrid composition. To overcome the solubility problem, the layer-by-layer method was used to prepare the films. This method allows a precise control of the deposition process. Experimental parameters were tested in order to evaluate their impact on the resulting film. The films morphology was investigated by microscopy and X-Ray diffraction techniques. These analyses reveal an interpenetrated structure of nano-crystals within the polymer matrix rather than a multilayered structure. Electrochemical and spectro electrochemical studies were performed on the hybrid material deposited by the LBL process. Finally the materials were tested in a solar cell configuration and the I=f(V) curves reveals a clear photovoltaic behaviour. (author)

  5. Magnetic Nanocomposite Cilia Sensors

    KAUST Repository

    Alfadhel, Ahmed

    2016-07-19

    Recent progress in the development of artificial skin concepts is a result of the increased demand for providing environment perception such as touch and flow sensing to robots, prosthetics and surgical tools. Tactile sensors are the essential components of artificial skins and attracted considerable attention that led to the development of different technologies for mimicking the complex sense of touch in humans. This dissertation work is devoted to the development of a bioinspired tactile sensing technology that imitates the extremely sensitive hair-like cilia receptors found in nature. The artificial cilia are fabricated from permanent magnetic, biocompatible and highly elastic nanocomposite material, and integrated on a giant magneto-impedance magnetic sensor to measure the stray field. A force that bends the cilia changes the stray field and is therefore detected with the magnetic sensor, providing high performance in terms of sensitivity, power consumption and versatility. The nanocomposite is made of Fe nanowires (NWs) incorporated into polydimethylsiloxane (PDMS). Fe NWs have a high remanent magnetization, due the shape anisotropy; thus, they are acting as permanent nano-magnets. This allows remote device operation and avoids the need for a magnetic field to magnetize the NWs, benefiting miniaturization and the possible range of applications. The magnetic properties of the nanocomposite can be easily tuned by modifying the NWs concentration or by aligning the NWs to define a magnetic anisotropy. Tactile sensors are realized on flexible and rigid substrates that can detect flow, vertical and shear forces statically and dynamically, with a high resolution and wide operating range. The advantage to operate the sensors in liquids and air has been utilized to measure flows in different fluids in a microfluidic channel. Various dynamic studies were conducted with the tactile sensor demonstrating the detection of moving objects or the texture of objects. Overall

  6. Handbook of luminescent semiconductor materials

    CERN Document Server

    Bergman, Leah

    2011-01-01

    Photoluminescence spectroscopy is an important approach for examining the optical interactions in semiconductors and optical devices with the goal of gaining insight into material properties. With contributions from researchers at the forefront of this field, Handbook of Luminescent Semiconductor Materials explores the use of this technique to study semiconductor materials in a variety of applications, including solid-state lighting, solar energy conversion, optical devices, and biological imaging. After introducing basic semiconductor theory and photoluminescence principles, the book focuses

  7. Metal semiconductor contacts and devices

    CERN Document Server

    Cohen, Simon S; Einspruch, Norman G

    1986-01-01

    VLSI Electronics Microstructure Science, Volume 13: Metal-Semiconductor Contacts and Devices presents the physics, technology, and applications of metal-semiconductor barriers in digital integrated circuits. The emphasis is placed on the interplay among the theory, processing, and characterization techniques in the development of practical metal-semiconductor contacts and devices.This volume contains chapters that are devoted to the discussion of the physics of metal-semiconductor interfaces and its basic phenomena; fabrication procedures; and interface characterization techniques, particularl

  8. TiO2/蒙脱石纳米复合材料结构组装过程与表征%Assembled Structure and Characterization of TiO2/Montmorillonite Nano-composites

    Institute of Scientific and Technical Information of China (English)

    古朝建; 彭同江; 孙红娟; 吕霞; 罗利明

    2012-01-01

    将氧化钛前驱体钛酸丁酯引入到不同用量十六烷基三甲基溴化铵(CTAB)柱撑蒙脱石的层间域中,经原位水解、脱羟、成核结晶作用制备TiO2/蒙脱石纳米复合结构材料.采用X射线衍射(XRD)分析手段对比研究了CTA+/蒙脱石、(Ti(OH)4/CTA+)/蒙脱石和TiO2/蒙脱石复合结构,揭示了不同阶段样品层间物在蒙脱石层间域中的组装方式.在季铵盐用量不同情况下,CTA+/蒙脱石复合物和(Ti(OH)4/CTA+)/蒙脱石复合物中季铵盐阳离子的排布方式均出现单层平卧、单层倾斜和双层倾斜排布,但单层倾斜和双层倾斜排布的倾斜角度不同,在(Ti(OH)4/CTA+)/蒙脱石层间域中季铵盐阳离子仍起到骨架作用;TiO2/蒙脱石复合材料中锐钛矿相含量随季铵盐用量的增加而增大,但锐钛矿晶粒的尺寸逐渐减小,蒙脱石层间域对锐钛矿相晶粒的长大和转化为金红石相都具有显著的阻滞作用.%TiO2/montmorillonite composites were prepared following in-situ hydrolyzing and thermal treatment route involves the hydrolysis of tetranbutyl titanate(TBT) and crystallization in the presence of organo-clays prepared from montmorillonite treated with different dosage of cetyitrimethyl ammonium bromide ( CTAB ). All the resulting materials ( CTA+/montmorillonite, ( Ti (OH )4/CTA+ )/ montmorillonite and TiO2/montmorillonite composites) were characterized contrastively by XRD. With different dosage of CTAB, assembly mode of CTA Vmontmorillonite and ( Ti (OH)4/CTA+ )/ montmorillonite in the interlayer space of montmorillonite are both lateral-monolayer, paraffin-type monolayer and paraffin-type bilayer, the angle of inclination for paraffin-type monolayer and paraffin-type bilayer are different, and cetyitrimethyl ammonium play a role of framework in the interlayer space of montmorillonite. The dosage of anatase in TiO2/montmorillonite composites increases as the dosage of CTAB increasing, but the size of anatase TiO2

  9. Preparation and properties of poly(vinylidene fluoride nanocomposites blended with graphene oxide coated silica hybrids

    Directory of Open Access Journals (Sweden)

    Q. Fu

    2012-04-01

    Full Text Available Graphene oxide coated silica hybirds (SiO2-GO were fabricated through electrostatic assembly in this work, then blended with poly(vinylidene fluoride (PVDF by solution mixing to make PVDF nanocomposites. The interfacial interaction was investigated by scanning electron microscopy (SEM, polarized optical microscopy (POM and Fourier transform infrared spectroscopy (FTIR. The results showed that the interfacial interaction was enhanced by adding of SiO2-GO and strong hydrogen bonds were observed. The as-made nanocomposites were investigated using standard tensile test and dynamic mechanical analysis (DMA measurements, mechanical properties of PVDF with SiO2-GO hybrids showed limited improvement.

  10. Review on the progress in synthesis and application of magnetic carbon nanocomposites

    Science.gov (United States)

    Zhu, Maiyong; Diao, Guowang

    2011-07-01

    This review focuses on the synthesis and application of nanostructured composites containing magnetic nanostructures and carbon-based materials. Great progress in fabrication of magnetic carbon nanocomposites has been made by developing methods including filling process, template-based synthesis, chemical vapor deposition, hydrothermal/solvothermal method, pyrolysis procedure, sol-gel process, detonation induced reaction, self-assembly method, etc. The applications of magnetic carbon nanocomposites expanded to a wide range of fields such as environmental treatment, microwave absorption, magnetic recording media, electrochemical sensor, catalysis, separation/recognization of biomolecules and drug delivery are discussed. Finally, some future trends and perspectives in this research area are outlined.

  11. Effect of Nanofiller Characteristics on Nanocomposite Properties

    Science.gov (United States)

    Working, Dennis C.; Lillehei, Peter T.; Lowther, Sharon E.; Siochi, Emilie J.; Kim, Jae-Woo; Sauti, Godfrey; Wise, Kristopher E.; Park, Cheol

    2016-01-01

    This report surveys the effect of nanofiller characteristics on nanocomposites fabricated with two polyimide matrices. Mechanical and electrical properties were determined. Microscopy results showed that matrix chemistry, nanofiller characteristics and processing conditions had significant impact on nanocomposite quality.

  12. Magnetoelectric polymer nanocomposite for flexible electronics

    KAUST Repository

    Alnassar, M.

    2015-03-06

    This paper reports the fabrication and characterization of a new type of magnetoelectric polymer nanocomposite that exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature. The multiferroic nanocomposite consists of high aspect ratio ferromagnetic iron nanowires embedded inside a ferroelectric co-polymer poly(vinylindene fluoride-trifluoroethylene), P(VDF-TrFE). The nanocomposite has been fabricated via a simple low temperature spin coating technique. Structural, ferromagnetic, ferroelectric, and magnetoelectric properties of the developed nanocomposite have been characterized. The nanocomposite films showed isotropic magnetic properties due to the random orientation of the iron nanowires inside the film. In addition, the embedded nanowires did not hinder the ferroelectric phase development of the nanocomposite. The developed nanocomposite showed a high magnetoelectric coupling response of 156 mV/cmOe measured at 3.1 kOe DC bias field. This value is among the highest reported magnetoelectric coupling in two phase particulate polymer nanocomposites.

  13. Forward SCT Module Assembly and Quality Control at IFIC Valencia

    CERN Document Server

    Mitsou, V A; Civera, J V; Costa, M J; Escobar, C; Fuster, J; García, C; García-Navarro, J E; González, F; González-Sevilla, S; Lacasta, C; Llosá, G; Martí i García, S; Miñano, M; Modesto, P; Nácher, J; Rodríguez-Oliete, R; Sánchez, F J; Sospedra, L; Strachko, V

    2007-01-01

    This note discusses the assembly and the quality control tests of 282 forward detector modules for the ATLAS Semiconductor Tracker assembled at the Instituto de Fisica Corpuscular (IFIC) in Valencia. The construction and testing procedures are outlined and the laboratory equipment is briefly described. Emphasis is given on the module quality achieved in terms of mechanical and electrical stability.

  14. Multielectrode Semiconductor Lasers①②

    Institute of Scientific and Technical Information of China (English)

    LUHngchang; SUNHongxia; 等

    1997-01-01

    Multielectrode semiconductor lasers are studied via the ray method.The expression of the output photon number of N-electrode semiconductor lasers has been derived for the first time.When N=1 or 2,the expression of the output photon number fits in that of one-electrode(general)or two-electrode semiconductor lasers perfectly.

  15. Fundamentals of power semiconductor devices

    CERN Document Server

    Baliga, BJayant

    2010-01-01

    Offers an in-depth treatment of the physics of operation of power semiconductor devices that are commonly used by the power electronics industry. This book shows analytical models for explaining the operation of various power semiconductor devices. It is suitable for practicing engineers in the power semiconductor device community.

  16. Graphene-aluminum nanocomposites

    International Nuclear Information System (INIS)

    Highlights: → We investigated the mechanical properties of aluminum and aluminum nanocomposites. → Graphene composite had lower strength and hardness compared to nanotube reinforcement. → Processing causes aluminum carbide formation at graphene defects. → The carbides in between grains is a source of weakness and lowers tensile strength. - Abstract: Composites of graphene platelets and powdered aluminum were made using ball milling, hot isostatic pressing and extrusion. The mechanical properties and microstructure were studied using hardness and tensile tests, as well as electron microscopy, X-ray diffraction and differential scanning calorimetry. Compared to the pure aluminum and multi-walled carbon nanotube composites, the graphene-aluminum composite showed decreased strength and hardness. This is explained in the context of enhanced aluminum carbide formation with the graphene filler.

  17. Graphene-aluminum nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Bartolucci, Stephen F., E-mail: stephen.bartolucci@us.army.mil [U.S. Army Benet Laboratories, Armaments Research Development and Engineering Center, Watervliet, NY 12189-4000 (United States); Paras, Joseph [U.S. Army Benet Laboratories, Armaments Research Development and Engineering Center, Watervliet, NY 12189-4000 (United States); Rafiee, Mohammad A. [Department of Mechanical Engineering and Materials Science, Rice University, Houston, TX 77005 (United States); Rafiee, Javad [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lee, Sabrina; Kapoor, Deepak [U.S. Army Benet Laboratories, Armaments Research Development and Engineering Center, Watervliet, NY 12189-4000 (United States); Koratkar, Nikhil, E-mail: koratn@rpi.edu [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2011-10-15

    Highlights: {yields} We investigated the mechanical properties of aluminum and aluminum nanocomposites. {yields} Graphene composite had lower strength and hardness compared to nanotube reinforcement. {yields} Processing causes aluminum carbide formation at graphene defects. {yields} The carbides in between grains is a source of weakness and lowers tensile strength. - Abstract: Composites of graphene platelets and powdered aluminum were made using ball milling, hot isostatic pressing and extrusion. The mechanical properties and microstructure were studied using hardness and tensile tests, as well as electron microscopy, X-ray diffraction and differential scanning calorimetry. Compared to the pure aluminum and multi-walled carbon nanotube composites, the graphene-aluminum composite showed decreased strength and hardness. This is explained in the context of enhanced aluminum carbide formation with the graphene filler.

  18. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias

    2013-01-01

    In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz nonlinear......In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz...... is determined by (but not equal to) the electron momentum relaxation rate. Single cycle pulses of light, irrespective of the frequency range to which they belong, inherently have an ultrabroadband spectrum covering many octaves of frequencies. Unlike the single-cycle pulses in optical domain, the THz pulses can...... be easily sampled with sub-cycle resolution using conventional femtosecond lasers. This makes the THz pulses accessible model tools for direct observation of general nonlinear optical phenomena occurring in the single-cycle regime....

  19. Biexcitons in semiconductor microcavities

    DEFF Research Database (Denmark)

    Borri, P.; Langbein, W.; Woggon, U.;

    2003-01-01

    In this paper, the present status of the experimental study of the optical properties of biexcitons in semiconductor microcavities is reviewed. In particular, a detailed investigation of a polariton-biexciton transition in a high-quality single quantum well GaAs/AlGaAs microcavity is reported...

  20. Characterisations of collagen-silver-hydroxyapatite nanocomposites

    Science.gov (United States)

    Ciobanu, C. S.; Popa, C. L.; Petre, C. C.; Jiga, G.; Trusca, R.; Predoi, D.

    2016-05-01

    The XRD analysis were performed to confirm the formation of hydroxyapatite structure in collagen-silver-hydroxyapatite nanocomposites. The molecular interaction in collagen-hydroxyapatite nanocomposites was highlighted by Fourier transform infrared spectroscopy (FTIR) analysis. The SEM showed a nanostructure of collagen-silverhydroxyapatite nanocomposites composed of nano needle-like particles in a veil with collagen texture. The presence of vibrational groups characteristics to the hydroxyapatite structure in collagen-silver-hydroxyapatite (AgHApColl) nanocomposites was investigated by FTIR.

  1. Bottom-up processing of thermoelectric nanocomposites from colloidal nanocrystal building blocks: the case of Ag{sub 2}Te-PbTe

    Energy Technology Data Exchange (ETDEWEB)

    Cadavid, Doris [Catalonia Institute for Energy Research, IREC (Spain); Ibanez, Maria [Universitat de Barcelona, Departament d' Electronica (Spain); Gorsse, Stephane [Universite de Bordeaux, ICMCB, CNRS (France); Lopez, Antonio M. [Universitat Politecnica de Catalunya, Departament d' Enginyeria Electronica (Spain); Cirera, Albert [Universitat de Barcelona, Departament d' Electronica (Spain); Morante, Joan Ramon; Cabot, Andreu, E-mail: acabot@irec.cat [Catalonia Institute for Energy Research, IREC (Spain)

    2012-12-15

    Nanocomposites are highly promising materials to enhance the efficiency of current thermoelectric devices. A straightforward and at the same time highly versatile and controllable approach to produce nanocomposites is the assembly of solution-processed nanocrystal building blocks. The convenience of this bottom-up approach to produce nanocomposites with homogeneous phase distributions and adjustable composition is demonstrated here by blending Ag{sub 2}Te and PbTe colloidal nanocrystals to form Ag{sub 2}Te-PbTe bulk nanocomposites. The thermoelectric properties of these nanocomposites are analyzed in the temperature range from 300 to 700 K. The evolution of their electrical conductivity and Seebeck coefficient is discussed in terms of the blend composition and the characteristics of the constituent materials.

  2. SCT Barrel Assembly Complete

    CERN Multimedia

    L. Batchelor

    As reported in the April 2005 issue of the ATLAS eNews, the first of the four Semiconductor Tracker (SCT) barrels, complete with modules and services, arrived safely at CERN in January of 2005. In the months since January, the other three completed barrels arrived as well, and integration of the four barrels into the entire barrel assembly commenced at CERN, in the SR1 building on the ATLAS experimental site, in July. Assembly was completed on schedule in September, with the addition of the innermost layer to the 4-barrel assembly. Work is now underway to seal the barrel thermal enclosure. This is necessary in order to enclose the silicon tracker in a nitrogen atmosphere and provide it with faraday-cage protection, and is a delicate and complicated task: 352 silicon module powertapes, 352 readout-fibre bundles, and over 400 Detector Control System sensors must be carefully sealed into the thermal enclosure bulkhead. The team is currently verifying the integrity of the low mass cooling system, which must be d...

  3. Circuit design techniques for non-crystalline semiconductors

    CERN Document Server

    Sambandan, Sanjiv

    2012-01-01

    Despite significant progress in materials and fabrication technologies related to non-crystalline semiconductors, fundamental drawbacks continue to limit real-world application of these devices in electronic circuits. To help readers deal with problems such as low mobility and intrinsic time variant behavior, Circuit Design Techniques for Non-Crystalline Semiconductors outlines a systematic design approach, including circuit theory, enabling users to synthesize circuits without worrying about the details of device physics. This book: Offers examples of how self-assembly can be used as a powerf

  4. Improving the photocatalytic performance of graphene-TiO2 nanocomposites via a combined strategy of decreasing defects of graphene and increasing interfacial contact.

    Science.gov (United States)

    Zhang, Yanhui; Zhang, Nan; Tang, Zi-Rong; Xu, Yi-Jun

    2012-07-01

    Incessant interest has been shown in the synthesis of graphene (GR)-semiconductor nanocomposites as photocatalysts aiming to utilize the excellent electron conductivity of GR to lengthen the lifetime of photoexcited charge carriers in the semiconductor and, hence, improve the photoactivity. However, research works focused on investigating how to make sufficient use of the unique electron conductivity of GR to design a more efficient GR-semiconductor photocatalyst have been quite lacking. Here, we show a proof-of-concept study on improving the photocatalytic performance of GR-TiO(2) nanocomposites via a combined strategy of decreasing defects of GR and improving the interfacial contact between GR and the semiconductor TiO(2). The GR-TiO(2) nanocomposite fabricated by this approach is able to make more sufficient use of the electron conductivity of GR, by which the lifetime and transfer of photoexcited charge carriers of GR-TiO(2) upon visible light irradiation will be improved more efficiently. This in turn leads to the enhancement of visible-light-driven photoactivity of GR-TiO(2) toward selective transformation of alcohols to corresponding aldehydes using molecular oxygen as a benign oxidant under ambient conditions. It is anticipated that our current work would inform ongoing efforts to exploit the rational design of smart, more efficient GR-semiconductor photocatalysts for conversion of solar to chemical energy by heterogeneous photocatalysis. PMID:22644332

  5. Synthesis, Morphology, and Optical Properties of Au/CdS Hybrid Nanocomposites Stabilized by Branched Polymer Matrices

    Directory of Open Access Journals (Sweden)

    V. A. Chumachenko

    2016-01-01

    Full Text Available Metal/semiconductor (Au/CdS nanocomposites were synthesized in the solution of branched D-g-PAA polymer. TEM and DLS of Au/CdS/D-g-PAA nanocomposites revealed complicated nanocomposite structure consisting of the Au nanoparticles (NPs of 6 nm in size surrounded by small CdS NPs with size of 3 nm. These nanocomposites formed the aggregates-clusters with average size of 50–800 nm. Absorption spectra of Au/CdS nanocomposites consist of the bands of excitons in CdS NPs and surface plasmons in Au ones. The surface plasmon band of gold NPs is red shifted and broadened in Au/CdS/D-g-PAA nanocomposites comparing to the one of Au NPs in Au/D-g-PAA proving the fact of close location of CdS and Au NPs in the synthesized Au/CdS/D-g-PAA nanocomposites. The PL spectra of Au/CdS nanocomposites originate from the radiative transitions in excitons in CdS NPs. The 4-fold increase of intensity of free exciton PL is observed for CdS NPs in Au/CdS/D-g-PAA comparing to CdS ones in CdS/D-g-PAA that is due to PL enhancement by local field of surface plasmons of Au NPs. Also, the 12-fold decrease of intensity of localized exciton PL is observed for CdS NPs in Au/CdS/D-g-PAA comparing to CdS ones in CdS/D-g-PAA. Most probably, it is due to passivation of the surface of CdS NPs carried out by the Au ones.

  6. Synthesis of Cr2O3/TNTs nanocomposite and its photocatalytic hydrogen generation under visible light irradiation

    International Nuclear Information System (INIS)

    A novel Cr2O3/TNTs nanocomposite was prepared by loaded suitable amount of amorphous Cr2O3 on titanate nanotubes (TNTs) via hydrothermal reaction and impregnation process. XRD, SEM and TEM results demonstrated that the amorphous Cr2O3 nanoparticles were homogeneously dispersed on the surface of TNTs. The diffuse reflectance UV-visible absorption spectra exhibited that the spectral response of TNTs was extended to visible light region by coupled with Cr2O3. The 2.5Cr2O3/TNTs nanocomposite showed the highest activity of hydrogen generation by photocatalytic water-splitting under visible light irradiation (λ > 400 nm). The high activity of H2 evolution for Cr2O3/TNTs nanocomposites was associated with the donor level in the forbidden band of TNTs semiconductor provided by dopant Cr3+ and a probably photocatalytic mechanism was proposed.

  7. CuFe2 O4 -CuO Nanocomposites as Promising Materials for Solar Hydrogen Generation

    Science.gov (United States)

    Razavi, Mehdi; Amrollahi, Pouya; Yazdimamaghani, Mostafa; Tayebi, Lobat; Vashaee, Daryoosh

    2014-03-01

    Currently, hydrogen is produced, almost exclusively, by waterelectrolysis. This method can take advantage of economies of scale and most established techniques of producing hydrogen. We developed a nanocomposite material system composed of CuFe2O4 and CuO semiconductor particles to produce hydrogen by electrolysis of water. The nanocomposite powder was prepared using the sol-gel method. Techniques of X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy and UV diffuse reflectance analysis were employed to characterize the synthesized products.The results confirmed the formation of CuFe2O4-CuO nanocomposite powder. The hydrogen evolution was successfully observed over the new hetero-system of CuFe2O4-CuO. The electrolysis activity depended on the concentration of CuO in the system. In order to enhance the hydrogen production, we further optimized the composite material versus the concentration of the compounds.

  8. In situ preparation of cubic Cu2O-RGO nanocomposites for enhanced visible-light degradation of methyl orange.

    Science.gov (United States)

    Zhang, Wei; Li, Xiaolin; Yang, Zhi; Tang, Xuehui; Ma, Yujie; Li, Ming; Hu, Nantao; Wei, Hao; Zhang, Yafei

    2016-07-01

    There has been a growing interest in gathering together photocatalysis of semiconductors, like cuprous oxide (Cu2O), and the excellent electron transmittability of graphene to produce a graphene-based semiconductor for photocatalytic degradation. In this paper, a mild one-pot in situ synthesis of cubic cuprous oxide-reduced graphene oxide (Cu2O-RGO) nanocomposites has been proposed for the removal of methyl orange. In contrast to pure cubic Cu2O particles under similar preparation conditions, the cubic Cu2O-RGO nanocomposites demonstrate enhanced visible-light-driven photocatalytic activity for methyl orange dye with a 100% degradation rate in 100 min. The enhanced photocatalytic performance is mainly attributed to the increased charge transportation, effective separation of photoelectrons from vacancies, and the improved contact area. PMID:27196539

  9. In situ preparation of cubic Cu2O-RGO nanocomposites for enhanced visible-light degradation of methyl orange

    Science.gov (United States)

    Zhang, Wei; Li, Xiaolin; Yang, Zhi; Tang, Xuehui; Ma, Yujie; Li, Ming; Hu, Nantao; Wei, Hao; Zhang, Yafei

    2016-07-01

    There has been a growing interest in gathering together photocatalysis of semiconductors, like cuprous oxide (Cu2O), and the excellent electron transmittability of graphene to produce a graphene-based semiconductor for photocatalytic degradation. In this paper, a mild one-pot in situ synthesis of cubic cuprous oxide-reduced graphene oxide (Cu2O-RGO) nanocomposites has been proposed for the removal of methyl orange. In contrast to pure cubic Cu2O particles under similar preparation conditions, the cubic Cu2O-RGO nanocomposites demonstrate enhanced visible-light-driven photocatalytic activity for methyl orange dye with a 100% degradation rate in 100 min. The enhanced photocatalytic performance is mainly attributed to the increased charge transportation, effective separation of photoelectrons from vacancies, and the improved contact area.

  10. Sequence assembly

    DEFF Research Database (Denmark)

    Scheibye-Alsing, Karsten; Hoffmann, S.; Frankel, Annett Maria;

    2009-01-01

    and plays an important role in processing the information generated by these methods. Here, we provide a comprehensive overview of the current publicly available sequence assembly programs. We describe the basic principles of computational assembly along with the main concerns, such as repetitive sequences...

  11. Properties of hybrid TiO2 -oligonucleotide nanocomposites

    International Nuclear Information System (INIS)

    Recent advancements in hybrid nanotechnology involving nucleic acids and inorganic molecules/structures are predominantly oriented towards cellular imaging or DNA microarray development or for nanoconstruction (such as assembly of ordered patterns of nanocrystals). Nevertheless, in this evolving field there is little work reported yet about the development of nanoparticles that can be used to manipulate biological materials in a novel way. We have synthesized TiO2 -DNA nanocomposites as new vehicles for biotechnology that express new biochemical properties, in an attempt to develop them into nanodevices that would be able to enter cells and conduct their functions in vivo and in situ. Absorption of light and ionizing radiation leads to charge separation in TiO2 , and nanocrystallites modified by the presence of oligonucleotides exhibit semiconducting through both constituents. In such a system charge pairs are instantaneously separated and electropositive holes accumulate on the oligonucleotide DNA, leading to a photo-/radio- catalytic DNA endonuclease reaction. In addition, hybrid nanocomposites of 4.5 nm TiO2 nanoparticles covalently attached to DNA oligonucleotides can be transferred across cellular and nuclear membranes using standard transfection techniques and retained inside mammalian cells. Therefore, TiO2 nanoparticles-biopolymer nanocomposites integrate intrinsic biological/ electrochemical (DNA) and photoelectrical (TiO2 ) properties of the biomolecule and inorganic components, which makes them suitable for development of new tools for biology and medicine

  12. Fluid cooled electrical assembly

    Science.gov (United States)

    Rinehart, Lawrence E.; Romero, Guillermo L.

    2007-02-06

    A heat producing, fluid cooled assembly that includes a housing made of liquid-impermeable material, which defines a fluid inlet and a fluid outlet and an opening. Also included is an electrical package having a set of semiconductor electrical devices supported on a substrate and the second major surface is a heat sink adapted to express heat generated from the electrical apparatus and wherein the second major surface defines a rim that is fit to the opening. Further, the housing is constructed so that as fluid travels from the fluid inlet to the fluid outlet it is constrained to flow past the opening thereby placing the fluid in contact with the heat sink.

  13. Synthesis, characterization and optical properties of polymer-based ZnS nanocomposites.

    Science.gov (United States)

    Tiwari, A; Khan, S A; Kher, R S; Dhoble, S J; Chandel, A L S

    2016-03-01

    Nanostructured polymer-semiconductor hybrid materials such as ZnS-poly(vinyl alcohol) (ZnS-PVA), ZnS-starch and ZnS-hydroxypropylmethyl cellulose (Zns-HPMC) are synthesized by a facile aqueous route. The obtained nanocomposites are characterized using various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV/vis spectroscopy and photoluminescence (PL). XRD studies confirm the zinc blende phase of the nanocomposites and indicate the high purity of the samples. SEM studies indicate small nanoparticles clinging to the surface of a bigger particle. The Energy Dispersive Analysis by X-rays (EDAX) spectrum reveals that the elemental composition of the nanocomposites consists primarily of Zn:S. FTIR studies indicate that the polymer matrix is closely associated with ZnS nanoparticles. The large number of hydroxyl groups in the polymer matrix facilitates the complexation of metal ions. The absorption spectra of the specimens show a blue shift in the absorption edge. The spectrum reveals an absorption edge at 320, 310 and 325 nm, respectively. PL of nanocomposites shows broad peaks in the violet-blue region (420-450 nm). The emission intensity changes with the nature of capping agent. The PL intensity of ZnS-HPMC nanocomposites is found to be highest among the studied nanocomposites. The results clearly indicate that hydroxyl-functionalized HPMC is much more effective at nucleating and stabilizing colloidal ZnS nanoparticles in aqueous suspensions compared with PVA and starch. PMID:26334003

  14. Semiconductor physics an introduction

    CERN Document Server

    Seeger, Karlheinz

    1999-01-01

    Semiconductor Physics - An Introduction - is suitable for the senior undergraduate or new graduate student majoring in electrical engineering or physics. It will also be useful to solid-state scientists and device engineers involved in semiconductor design and technology. The text provides a lucid account of charge transport, energy transport and optical processes, and a detailed description of many devices. It includes sections on superlattices and quantum well structures, the effects of deep-level impurities on transport, the quantum Hall effect and the calculation of the influence of a magnetic field on the carrier distribution function. This 6th edition has been revised and corrected, and new sections have been added to different chapters.

  15. Compound semiconductor device modelling

    CERN Document Server

    Miles, Robert

    1993-01-01

    Compound semiconductor devices form the foundation of solid-state microwave and optoelectronic technologies used in many modern communication systems. In common with their low frequency counterparts, these devices are often represented using equivalent circuit models, but it is often necessary to resort to physical models in order to gain insight into the detailed operation of compound semiconductor devices. Many of the earliest physical models were indeed developed to understand the 'unusual' phenomena which occur at high frequencies. Such was the case with the Gunn and IMPATI diodes, which led to an increased interest in using numerical simulation methods. Contemporary devices often have feature sizes so small that they no longer operate within the familiar traditional framework, and hot electron or even quantum­ mechanical models are required. The need for accurate and efficient models suitable for computer aided design has increased with the demand for a wider range of integrated devices for operation at...

  16. Optoelectronic and nonlinear optical processes in low dimensional semiconductors

    Indian Academy of Sciences (India)

    B P Singh

    2006-11-01

    Spatial confinement of quantum excitations on their characteristic wavelength scale in low dimensional materials offers unique possibilities to engineer the electronic structure and thereby control their physical properties by way of simple manipulation of geometrical parameters. This has led to an overwhelming interest in quasi-zero dimensional semiconductors or quantum dots as tunable materials for multitude of exciting applications in optoelectronic and nonlinear optical devices and quantum information processing. Large nonlinear optical response and high luminescence quantum yield expected in these systems is a consequence of huge enhancement of transition probabilities ensuing from quantum confinement. High quantum efficiency of photoluminescence, however, is not usually realized in the case of bare semiconductor nanoparticles owing to the presence of surface states. In this talk, I will focus on the role of quantum confinement and surface states in ascertaining nonlinear optical and optoelectronic properties of II–VI semiconductor quantum dots and their nanocomposites. I will also discuss the influence of nonlinear optical processes on their optoelectronic characteristics.

  17. Shape memory polyurethane nanocomposites

    Science.gov (United States)

    Cao, Feina

    stress could be tailored by the processing conditions. The recovery stress increased with decrease of stretching rate, and increase of stretching temperature and stretch ratio. The recovery stress of polyurethane/clay nanocomposites largely depended on the degree of clay exfoliation. Higher recovery stress was found in nanocomposites with better clay dispersion. The dependence of stress relaxation on stretching conditions, clay type, and clay content was also investigated and related to shape recovery stress. It was found that stress relaxation occurred more easily in the presence of nanoclay.

  18. Coherent interface structures and intergrain Josephson coupling in dense MgO/Mg2Si/MgB2 nanocomposites

    Science.gov (United States)

    Ueno, Katsuya; Nagashima, Yukihito; Seto, Yusuke; Matsumoto, Megumi; Sakurai, Takahiro; Ohta, Hitoshi; Takahashi, Kazuyuki; Uchino, Takashi

    2016-07-01

    Many efforts are under way to control the structure of heterointerfaces in nanostructured composite materials for designing functionality and engineering application. However, the fabrication of high-quality heterointerfaces is challenging because the crystal/crystal interface is usually the most defective part of the nanocomposite materials. In this work, we show that fully dense insulator (MgO)/semiconductor(Mg2Si)/superconductor(MgB2) nanocomposites with atomically smooth and continuous interfaces, including epitaxial-like MgO/Mg2Si interfaces, are obtained by solid phase reaction between metallic magnesium and a borosilicate glass. The resulting nanocomposites exhibit a semiconductor-superconducting transition at 36 K owing to the MgB2 nanograins surrounded by the MgO/Mg2Si matrix. This transition is followed by the intergrain phase-lock transition at ˜24 K due to the construction of Josephson-coupled network, eventually leading to a near-zero resistance state at 17 K. The method not only provides a simple process to fabricate dense nanocomposites with high-quality interfaces, but also enables to investigate the electric and magnetic properties of embedded superconducting nanograins with good intergrain coupling.

  19. How semiconductor nanoplatelets form

    OpenAIRE

    Riedinger, Andreas; Ott, Florian D.; Mule, Aniket; Mazzotti, Sergio; Knuesel, Philippe N.; Kress, Stephan J. P.; Prins, Ferry; Erwin, Steven C.; Norris, David J.

    2016-01-01

    Colloidal nanoplatelets - quasi-two-dimensional sheets of semiconductor exhibiting efficient, spectrally pure fluorescence - form when liquid-phase syntheses of spherical quantum dots are modified. Despite intense interest in their properties, the mechanism behind their anisotropic shape and precise atomic-scale thickness remains unclear, and even counterintuitive when their crystal structure is isotropic. One commonly accepted explanation is that nanoclusters nucleate within molecular templa...

  20. Isotopically controlled semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Haller, Eugene E.

    2006-06-19

    The following article is an edited transcript based on the Turnbull Lecture given by Eugene E. Haller at the 2005 Materials Research Society Fall Meeting in Boston on November 29, 2005. The David Turnbull Lectureship is awarded to recognize the career of a scientist who has made outstanding contributions to understanding materials phenomena and properties through research, writing, and lecturing, as exemplified by the life work of David Turnbull. Haller was named the 2005 David Turnbull Lecturer for his 'pioneering achievements and leadership in establishing the field of isotopically engineered semiconductors; for outstanding contributions to materials growth, doping and diffusion; and for excellence in lecturing, writing, and fostering international collaborations'. The scientific interest, increased availability, and technological promise of highly enriched isotopes have led to a sharp rise in the number of experimental and theoretical studies with isotopically controlled semiconductor crystals. This article reviews results obtained with isotopically controlled semiconductor bulk and thin-film heterostructures. Isotopic composition affects several properties such as phonon energies, band structure, and lattice constant in subtle, but, for their physical understanding, significant ways. Large isotope-related effects are observed for thermal conductivity in local vibrational modes of impurities and after neutron transmutation doping. Spectacularly sharp photoluminescence lines have been observed in ultrapure, isotopically enriched silicon crystals. Isotope multilayer structures are especially well suited for simultaneous self- and dopant-diffusion studies. The absence of any chemical, mechanical, or electrical driving forces makes possible the study of an ideal random-walk problem. Isotopically controlled semiconductors may find applications in quantum computing, nanoscience, and spintronics.

  1. Theory aided design and analysis of dielectric and semiconductor components for organic field-effect transistors

    Science.gov (United States)

    Dibenedetto, Sara Arlene

    Perfluoroacyl/acyl-derivatized quaterthiophens are developed and synthesized. The frontier molecular orbital energies of these compounds are studied by optical spectroscopy and electrochemistry while solid-state/film properties are investigated by thermal analysis, x-ray diffraction, and scanning electron microscopy. Organic thin film transistors (OTFTs) performance parameters are discussed in terms of the interplay between semiconductor molecular energetics and film morphologies/microstructures. The majority charge carrier type and mobility exhibit a strong correlation with the regiochemistry of perfluoroarene incorporation. In quaterthiophene-based semiconductors, carbonyl-functionalization allows tuning of the majority carrier type from p-type to ambipolar and to n-type. In situ conversion of a p-type semiconducting film to n-type film is also demonstrated. The design of chemical and film microstructural alternative hybrid organic-inorganic gate dielectrics is described using the classic Clausius-Mossotti relation. The Maxwell-Wagner effective medium model is used to compute the effective dielectric permittivity of two types of dielectrics self-assembled nanodielectrics (SANDs) and crosslinked polymer blends (CPBs). In these calculations showing good agreement between theory and experiment, it is found that greater capacitances should be achievable with mixed composites than with layered composites. With this insight, a series of mixed metal oxide-polyolefin nanocomposites is synthesized via in-situ olefin polymerization using the single-site metallocene catalysts. By integrating organic and inorganic constituents, the resulting hybrid material exhibit high permittivity (from the inorganic inclusions) and high breakdown strength, mechanical flexibility, and facile processability (from the polymer matrices). In order to better optimize the capacitance and leakage current of hybrid organic-inorganic dielectrics, the capacitance, leakage current and OFET gate

  2. Polymer-Layer Silicate Nanocomposites

    DEFF Research Database (Denmark)

    Potarniche, Catalina-Gabriela

    with a spectacular improvement up to 300 % in impact strength were obtained. In the second part of this study, layered silicate bio-nanomaterials were obtained starting from natural compounds and taking into consideration their biocompatibility properties. These new materials may be used for drug delivery systems......Nowadays, some of the material challenges arise from a performance point of view as well as from recycling and biodegradability. Concerning these aspects, the development of polymer layered silicate nanocomposites can provide possible solutions. This study investigates how to obtain polymer layered...... toughness-stiffness requirements. The new compatibilizer system used to obtain nanocomposites, presented an improvement of 8-20 % in tensile strength, 15-34 % in Young’s modulus, 23-34 % in fatigue tests and 20-58% in degree of crystalline phase. By introducing a rubbery phase as modifier, nanocomposites...

  3. Kirigami Nanocomposites as Wide-Angle Diffraction Gratings.

    Science.gov (United States)

    Xu, Lizhi; Wang, Xinzhi; Kim, Yoonseob; Shyu, Terry C; Lyu, Jing; Kotov, Nicholas A

    2016-06-28

    Beam steering devices represent an essential part of an advanced optics toolbox and are needed in a spectrum of technologies ranging from astronomy and agriculture to biosensing and networked vehicles. Diffraction gratings with strain-tunable periodicity simplify beam steering and can serve as a foundation for light/laser radar (LIDAR/LADAR) components of robotic systems. However, the mechanical properties of traditional materials severely limit the beam steering angle and cycle life. The large strain applied to gratings can severely impair the device performance both in respect of longevity and diffraction pattern fidelity. Here, we show that this problem can be resolved using micromanufactured kirigami patterns from thin film nanocomposites based on high-performance stiff plastics, metals, and carbon nanotubes, etc. The kirigami pattern of microscale slits reduces the stochastic concentration of strain in stiff nanocomposites including those made by layer-by-layer assembly (LBL). The slit patterning affords reduction of strain by 2 orders of magnitude for stretching deformation and consequently enables reconfigurable optical gratings with over a 100% range of period tunability. Elasticity of the stiff nanocomposites and plastics makes possible cyclic reconfigurability of the grating with variable time constant that can also be referred to as 4D kirigami. High-contrast, sophisticated diffraction patterns with as high as fifth diffraction order can be obtained. The angular range of beam steering can be as large as 6.5° for a 635 nm laser beam compared to ∼1° in surface-grooved elastomer gratings and ∼0.02° in MEMS gratings. The versatility of the kirigami patterns, the diversity of the available nanocomposite materials, and their advantageous mechanical properties of the foundational materials open the path for engineering of reconfigurable optical elements in LIDARs essential for autonomous vehicles and other optical devices with spectral range determined

  4. Ultrafast charge carrier dynamics in Au/semiconductor nanoheterostructures

    Science.gov (United States)

    Lambright, Scott

    The charge carrier dynamics in several Au/semiconductor core/shell heterostructures were examined. Firstly, Au/CdS core/shell nanocomposites were synthesized in a four step procedure culminating in a cation exchange performed on the shell. Previous studies of the ultrafast carrier dynamics in Au/CdS nanocomposites with epitaxial boundary regions reported the suppression of plasmon character in transient absorption spectra accompanied by broadband photoinduced absorption. The coupling of electron wavefunctions with lattice defects at the boundary of the two domains has been blamed for these phenomena. In the current study, transmission electron micrographs of Au/CdS synthesized using cation exchange showed no evidence of strain on the lattice of either component, while femtosecond transient absorption data show the retention of bleach regions attributed to CdS's 1S(e)-1S3/2(h) transition and Au's plasmon resonance. Accelerated rates of bleach recovery for both excitations ( tauexiton ≈ 300 ps, tauplasmon ≈ .7 ps) indicated that the interaction of Au and CdS domains leads to faster relaxation to their respective photoexcitations when compared to relaxation times in isolated Au and CdS nanoparticles. It was believed that the Au/CdS boundary was non-epitaxial in the presented core/shell nanocomposites. Secondly, these non-epitaxial Au/CdS core/shells were subsequently used to demonstrate near-field energy transfer from 5 nm diameter Au cores to CdS-encapsulated CdSe quantum dots. To this end, Au/CdS and CdSe/CdS nanocrystals were embedded in semiconductor-matrix-encapsulated-nanocrystal-arrays (SMENA) together. The encapsulation of both domains in the high band-gap semiconductor CdS was a means to suppress charge transfer between the two nanoparticles. The fluorescence intensity in these films was enhanced 6-fold in some cases as a result of the presence of Au domains. It was also demonstrated that the fluorescence enhancement was independent of the potential

  5. Modeling Percolation in Polymer Nanocomposites by Stochastic Microstructuring

    Directory of Open Access Journals (Sweden)

    Matias Soto

    2015-09-01

    Full Text Available A methodology was developed for the prediction of the electrical properties of carbon nanotube-polymer nanocomposites via Monte Carlo computational simulations. A two-dimensional microstructure that takes into account waviness, fiber length and diameter distributions is used as a representative volume element. Fiber interactions in the microstructure are identified and then modeled as an equivalent electrical circuit, assuming one-third metallic and two-thirds semiconductor nanotubes. Tunneling paths in the microstructure are also modeled as electrical resistors, and crossing fibers are accounted for by assuming a contact resistance associated with them. The equivalent resistor network is then converted into a set of linear equations using nodal voltage analysis, which is then solved by means of the Gauss–Jordan elimination method. Nodal voltages are obtained for the microstructure, from which the percolation probability, equivalent resistance and conductivity are calculated. Percolation probability curves and electrical conductivity values are compared to those found in the literature.

  6. ZnS/PVA nanocomposites for nonlinear optical applications

    Science.gov (United States)

    Ozga, K.; Michel, J.; Nechyporuk, B. D.; Ebothé, J.; Kityk, I. V.; Albassam, A. A.; El-Naggar, A. M.; Fedorchuk, A. O.

    2016-07-01

    We have found a correlation between ZnS nanocomposite nonlinear optical features and technological processing using electrolytic method. In the earlier researches this factor was neglected. However, it may open a new stage for operation by photovoltaic features of the well known semiconductors within a wide range of magnitudes. The titled nanostructured zinc sulfide (ZnS) was synthesized by electrolytic method. The obtained ZnS nano-crystallites possessed nano-particles sizes varying within 1.6 nm…1.8 nm. The titled samples were analyzed by XRD, HR-TEM, STEM, and nonlinear optical methods such as photo-induced two-photon absorption (TPA) and second harmonic generation (SHG). For this reason the nano-powders were embedded into the photopolymer poly(vinyl) alcohol (PVA) matrices. Role of aggregation in the mentioned properties is discussed. Possible origin of the such correlations are discussed.

  7. Stretchable piezoelectric nanocomposite generator

    Science.gov (United States)

    Park, Kwi-Il; Jeong, Chang Kyu; Kim, Na Kyung; Lee, Keon Jae

    2016-06-01

    Piezoelectric energy conversion that generate electric energy from ambient mechanical and vibrational movements is promising energy harvesting technology because it can use more accessible energy resources than other renewable natural energy. In particular, flexible and stretchable piezoelectric energy harvesters which can harvest the tiny biomechanical motions inside human body into electricity properly facilitate not only the self-powered energy system for flexible and wearable electronics but also sensitive piezoelectric sensors for motion detectors and in vivo diagnosis kits. Since the piezoelectric ZnO nanowires (NWs)-based energy harvesters (nanogenerators) were proposed in 2006, many researchers have attempted the nanogenerator by using the various fabrication process such as nanowire growth, electrospinning, and transfer techniques with piezoelectric materials including polyvinylidene fluoride (PVDF) polymer and perovskite ceramics. In 2012, the composite-based nanogenerators were developed using simple, low-cost, and scalable methods to overcome the significant issues with previously-reported energy harvester, such as insufficient output performance and size limitation. This review paper provides a brief overview of flexible and stretchable piezoelectric nanocomposite generator for realizing the self-powered energy system with development history, power performance, and applications.

  8. Aerogel nanocomposite materials

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, A.J.; Ayers, M.; Cao, W. [Lawrence Berkeley Laboratory, CA (United States)] [and others

    1995-05-01

    Aerogels are porous, low density, nanostructured solids with many unusual properties including very low thermal conductivity, good transparency, high surface area, catalytic activity, and low sound velocity. This research is directed toward developing new nanocomposite aerogel materials for improved thermal insulation and several other applications. A major focus of the research has been to further increase the thermal resistance of silica aerogel by introducing infrared opacification agents into the aerogel to produce a superinsulating composite material. Opacified superinsulating aerogel permit a number of industrial applications for aerogel-based insulation. The primary benefits from this recently developed superinsulating composite aerogel insulation are: to extend the range of applications to higher temperatures, to provide a more compact insulation for space sensitive-applications, and to lower costs of aerogel by as much as 30%. Superinsulating aerogels can replace existing CFC-containing polyurethane in low temperature applications to reduce heat losses in piping, improve the thermal efficiency of refrigeration systems, and reduce energy losses in a variety of industrial applications. Enhanced aerogel insulation can also replace steam and process pipe insulation in higher temperature applications to substantially reduce energy losses and provide much more compact insulation.

  9. Graphene/Polymer Nanocomposites

    Science.gov (United States)

    Macosko, Chris

    2010-03-01

    Graphite has attracted large attention as a reinforcement for polymers due to its ability to modify electrical conductivity, mechanical and gas barrier properties of host polymers and its potentially lower cost than carbon nanotubes. If graphite can be exfoliated into atomically thin graphene sheets, it is possible to achieve the highest property enhancements at the lowest loading. However, small spacing and strong van der Waals forces between graphene layers make exfoliation of graphite via conventional composite manufacturing strategies challenging. Recently, two different approaches to obtain exfoliated graphite prior to blending were reported: thermal treatment (Schniepp et al., JACS 2006) and chemical modification (Stankovich et al., J Mat Chem 2006). Both start from graphite oxide. We will describe and evaluate these exfoliation approaches and the methods used to produce graphene reinforced thermoplastics, particularly polyester, polycarbonate and polyurethane nanocomposites. Three different dispersion methods - melt blending, solution mixing and in-situ polymerization -- are compared. Characterization of dispersion quality is illustrated with TEM, rheology and in electrical conductivity, tensile modulus and gas barrier property improvement.

  10. Quantum dot sensitized solar cell based on poly (3-hexyl thiophene)/CdSe nanocomposites

    Science.gov (United States)

    Sehgal, Preeti; Narula, Anudeep kumar

    2015-10-01

    The optoelectronic properties of P3HT-CdSe nanocomposites prepared by insitu chemical oxidative polymerization were studied. CdSe QDs were synthesized by hot injection method using tri octyl phosphine oxide (TOPO) as capping ligand whereas the P3HT polymer was prepared by chemical oxidative polymerization. FTIR studies confirmed the regioregularity of the P3HT and revealed the chemical interaction of P3HT and CdSe in nanocomposite. Absorption studies showed blue shift for the nanocomposites as compare to pristine P3HT, the electron transfer from conducting polymer to the CdSe was detected by the measurements of quenching of photoluminescence from conducting polymer after the addition of semiconductor nano crystals which confirmed that an optimum amount of nanoparticles provide networking in hybrid composites. The optimal result for device prepared by P3HT-CdSe nanocomposites was open circuit voltage (Voc) 0.5, short circuit current density (Jsc) 0.66, Fill factor (FF) 0.6855 and efficiency (η) 0.22%.

  11. Aerosol assisted chemical vapor deposition using nanoparticle precursors: a route to nanocomposite thin films.

    Science.gov (United States)

    Palgrave, Robert G; Parkin, Ivan P

    2006-02-01

    Gold nanoparticle and gold/semiconductor nanocomposite thin films have been deposited using aerosol assisted chemical vapor deposition (CVD). A preformed gold colloid in toluene was used as a precursor to deposit gold films onto silica glass. These nanoparticle films showed the characteristic plasmon absorption of Au nanoparticles at 537 nm, and scanning electron microscopic (SEM) imaging confirmed the presence of individual gold particles. Nanocomposite films were deposited from the colloid concurrently with conventional CVD precursors. A film of gold particles in a host tungsten oxide matrix resulted from co-deposition with [W(OPh)(6)], while gold particles in a host titania matrix resulted from co-deposition with [Ti(O(i)Pr)(4)]. The density of Au nanoparticles within the film could be varied by changing the Au colloid concentration in the original precursor solution. Titania/gold composite films were intensely colored and showed dichromism: blue in transmitted light and red in reflected light. They showed metal-like reflection spectra and plasmon absorption. X-ray photoelectron spectroscopy and energy-dispersive X-ray analysis confirmed the presence of metallic gold, and SEM imaging showed individual Au nanoparticles embedded in the films. X-ray diffraction detected crystalline gold in the composite films. This CVD technique can be readily extended to produce other nanocomposite films by varying the colloids and precursors used, and it offers a rapid, convenient route to nanoparticle and nanocomposite thin films. PMID:16448130

  12. Humidity sensing properties of Cu2O-PEPC nanocomposite films

    Institute of Scientific and Technical Information of China (English)

    Kh.S.Karimov; M.Saleem; Z.M.Karieva; A.Mateen; M.Tariq Saeed Chani; Q.Zafar

    2012-01-01

    A blend of copper oxide nanopowder (Cu2O),3 wt.%,and poly-N-epoxypropylcarbazole (PEPC),2 wt.%,in benzol was drop-casted on glass substrates with pre-deposited surface-type silver electrodes for the fabrication of Cu2O-PEPC nanocomposite thin films.The thicknesses of the Cu2O-PEPC films were in the range of 10-13 μm.The effect of humidity on the electrical properties of the nanocomposite films was investigated by measuring the capacitance and dissipation of the samples at two different frequencies of the applied voltage:120 Hz and 1 kHz.The AC resistance of the samples was determined from the dissipation values,and the DC resistance was measured directly.The effect of ageing on the humidity sensing properties of the nanocomposite was observed.After ageing,it was observed that at 120 Hz and 1 kHz,under a humidity of up to 86% RH,the capacitance of the cell increased by 85 and 8 times,and the resistance decreased by 345 and 157 times,accordingly,with respect to 30% RH conditions.It was found that with an increase in frequency,the capacitance and resistance of the samples decreased.It is assumed that the humidity response of the cell is associated with the diffusion of water vapors and doping of the semiconductor nanocomposite by water molecules.

  13. Synthesis and sensor applications of MoS2-based nanocomposites

    Science.gov (United States)

    Zhang, Wensi; Zhang, Panpan; Su, Zhiqiang; Wei, Gang

    2015-11-01

    Molybdenum disulfide (MoS2) is a typical layered transition-metal dichalcogenide material, which has aroused a great deal of interest in the past few years. Recently, more and more attention has been focused on the synthesis and applications of MoS2-based nanocomposites. In this review, we aimed to present a wider view of the synthesis of various MoS2-based nanocomposites for sensor and biosensor applications. We highlighted the potential methods like self-assembly, hydrothermal reaction, chemical vapour deposition, electrospinning, as well as microwave and laser beam treatments for the successful preparation of MoS2-based nanocomposites. On the other hand, three representative types of detection devices fabricated by the MoS2-based nanocomposites, field-effect transistor, optical, and electrochemical sensors, were introduced in detail and discussed fully. The relationships between the sensing performances and the special nanostructures within the MoS2-based nanocomposites were presented and discussed.

  14. Humidity sensing properties of CNT-OD-VETP nanocomposite films

    Science.gov (United States)

    Saleem, M.; Karimov, Kh. S.; Karieva, Z. M.; Mateen, A.

    2010-11-01

    In this study, the blend of orange dye (OD), C 17H 17N 5O 2 (5 wt%), vinyl-ethynyl-trimethyl-piperidole (VETP), C 12H 19NO, (5 wt%) and carbon nanotube (CNT) powder (10 wt%) in a mixture of distilled water (80 wt%) and spirit were drop-casted on glass substrates with pre-deposited surface-type silver electrodes to fabricate CNT-OD-VETP nanocomposite thin films. In the process of thin films deposition, 2 V DC was applied to Ag electrodes. The thicknesses of the CNT-OD-VETP films were in the range of 10-15 μm. The I-V characteristics of the surface-type Ag/CNT-OD-VETP/Ag samples showed rectification behavior. The effect of humidity on the electrical properties of the nanocomposite films was investigated by measurement of the capacitance and dissipation of the samples at two different frequencies of the applied voltage: 120 Hz and 1 kHz. The resistance of the samples was determined from values of dissipation. It was observed that at 120 Hz and 1 kHz, under humidity of up to 90% RH, the capacitance of the cell increased by 7.4×10 3 and 740 times and resistance decreased by 2.3×10 4 and 3.8×10 4 times, accordingly, with respect to 40% RH conditions. The average response and recovery times of the films were obtained by capacitance-time measurements to evaluate the dynamics of the water vapor absorption and desorption processes. The experimental results have been supported by the simulation of the capacitance-humidity relationship. It is assumed that the humidity response of the cell is associated with diffusion of water vapors and doping of the semiconductor nanocomposite by water molecules.

  15. Enhanced visible-light-responsive photocatalytic property of PbS-sensitized K{sub 4}Nb{sub 6}O{sub 17} nanocomposite photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Wenquan; Shao, Meiyi; Liu, Li [College of Chemical Engineering, Hebei United University, Tangshan 063009 (China); Liang, Yinghua, E-mail: Liangyh@heuu.edu.cn [College of Chemical Engineering, Hebei United University, Tangshan 063009 (China); Rana, Dipak [Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis Pasteur St., Ottawa, K1N 6N5 Canada (Canada)

    2013-07-01

    PbS-loaded K{sub 4}Nb{sub 6}O{sub 17} nanocomposite photocatalysts (hereafter designated as PbS@K{sub 4}Nb{sub 6}O{sub 17}) were prepared via a reverse microemulsion method. The nanocomposite materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray fluorescence spectrometer, ultraviolet–visible diffuse reflection spectra, photoluminescence measurement and X-ray photoelectron spectroscopy. The nano-semiconductor PbS@K{sub 4}Nb{sub 6}O{sub 17} composites have the layered structure and the band gaps of the two semiconductors couple. The nanocomposite PbS@K{sub 4}Nb{sub 6}O{sub 17} exhibited a strong photocatalytic activity for degradation of Rhodamine B (hereafter referred as RhB) under visible light irradiation. Moreover, the nanocomposite PbS(25 wt.%)@K{sub 4}Nb{sub 6}O{sub 17} shows the highest photocatalytic activity, the decomposition rate of RhB solution is about 71% after 120 min under visible light irradiation, which is over that of the pure K{sub 4}Nb{sub 6}O{sub 17} and pure PbS particles. The nanocomposite photocatalysts proved to be fairly photostable through the recyclability experiments. The mechanism of separation of the photogenerated electrons and holes at the PbS@K{sub 4}Nb{sub 6}O{sub 17} was discussed.

  16. Highly efficient photocatalytic hydrogen evolution of graphene/YInO3 nanocomposites under visible light irradiation

    Science.gov (United States)

    Ding, Jianjun; Yan, Wenhao; Xie, Wei; Sun, Song; Bao, Jun; Gao, Chen

    2014-01-01

    Visible-light-driven hydrogen evolution with high efficiency is important in the current photocatalysis research. Here we report for the first time the design and synthesis of a new graphene-semiconductor nanocomposite consisting of YInO3 nanoparticles and two-dimensional graphene sheets as efficient photocatalysts for hydrogen evolution under visible light irradiation. The graphene/YInO3 nanocomposites were synthesized using a facile solvothermal method in which the formation of graphene and the deposition of YInO3 nanoparticles on the graphene sheets can be achieved simultaneously. The addition of graphene as a cocatalyst can narrow the band gap of YInO3 to visible photon energy and prolong the separation and lifetime of electron-hole pairs by the chemical bonding between YInO3 and graphene. The photocatalytic reaction with this nanocomposite reaches a high H2 evolution rate of 400.4 μmol h-1 g-1 when the content of graphene is 0.5 wt%, over 127 and 3.7 times higher than that of pure YInO3 and Pt/YInO3, respectively. This work can provide an effective approach to the fabrication of graphene-based photocatalysts with high performance in the field of energy conversion.Visible-light-driven hydrogen evolution with high efficiency is important in the current photocatalysis research. Here we report for the first time the design and synthesis of a new graphene-semiconductor nanocomposite consisting of YInO3 nanoparticles and two-dimensional graphene sheets as efficient photocatalysts for hydrogen evolution under visible light irradiation. The graphene/YInO3 nanocomposites were synthesized using a facile solvothermal method in which the formation of graphene and the deposition of YInO3 nanoparticles on the graphene sheets can be achieved simultaneously. The addition of graphene as a cocatalyst can narrow the band gap of YInO3 to visible photon energy and prolong the separation and lifetime of electron-hole pairs by the chemical bonding between YInO3 and graphene. The

  17. Controlling Carrier Dynamics using Quantum-Confined Semiconductor Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Beard, Matthew C.; Klimov, Victor I.

    2016-06-01

    The articles included in this special issue of Chemical Physics explore the use of quantum-confined semiconductor nanocrystals to control the flow of energy and/or charge. Colloidal quantum-confined semiconductor nanostructures are an emerging class of functional materials being developed for novel opto-electronic applications. In the last few years numerous examples in the literature have emerged where novel nanostructures have been tailored such as to achieve a specific function thus moving the field from the stage of discovery of novel behaviors to that of control of nanostructure properties. In addition to the internal structure of the NCs their assemblies can be tailored to achieve emergent properties and add additional control parameters that determine the final opto-electronic properties. These principles are explored via variations in shape, size, surface ligands, heterostructuring, morphology, composition, and assemblies and are demonstrated through measurements of excited state processes, such as Auger recombination; photoluminescence; charge separation and charge transport.

  18. Direct-write maskless lithography of LBL nanocomposite films and its prospects for MEMS technologies.

    Science.gov (United States)

    Bai, Yongxiao; Ho, Szushen; Kotov, Nicholas A

    2012-08-01

    Application of nanocomposites in MEMS, flexible electronics, and biomedical devices is likely to demonstrate new performance standards and resolve a number of difficult technical problems enabled by the unique combinations of electrical, optical, and mechanical properties. This study explores the possibility of making microscale nanocomposite patterns using the fusion of two highly versatile techniques: direct-write maskless UV patterning and layer-by-layer assembly (LBL). Together they can be applied to the production of a wide variety of nanostructured coatings with complex patterns. Single-walled carbon nanotube (SWNT) and gold nanoparticle LBL nanocomposites assembled with chitosan (CH) were made into prototypical patterns such as concentric helices and bus-line-and-stimulation-pads (BLASPs) used in flexible antennas and neuroprosthetic devices. The spatial resolution of the technique was established with the standard line grids to be at least 1 μm. Gold nanoparticle films revealed better accuracy and higher resolution in direct-write patterning than SWNT composites, possibly due to the granular rather than fibrous nature of the composites. The conductivity of the patterned composites was 6.45 × 10(-5)Ω m and 3.80 × 10(-6)Ω m at 20 °C for nanotube and nanoparticle composites, respectively; in both cases it exceeds electrical parameters of similar composites. Fundamental and technological prospects of nanocomposite MEMS devices in different areas including implantable biomedical, sensing, and optical devices are discussed.

  19. Optical and electrical properties of electrochemically deposited polyaniline/CeO{sub 2} hybrid nanocomposite film

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Anees A.; Khan, M. A. M.; Khan, M. Naziruddin; Alrokayan, Salman A.; Alhoshan, M.; Alsalhi, M. S., E-mail: aneesaansari@gmail.com [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh-11451, P. O. Box-2454 (Saudi Arabia)

    2011-04-15

    This paper reports the optical and electrical properties of electrochemically deposited polyaniline (PANI)/cerium oxide (CeO{sub 2}) hybrid nano-composite film onto indium-tin-oxide (ITO) glass substrate. UV-visible spectroscopy and I-V characteristic were performed to study the optical and electrical parameters of the electrochemically deposited film. The film exhibited a strong absorption below 400 nm (3.10 eV) with a well defined absorbance peak at around 285 nm (4.35 eV). The estimated band gap of the CeO{sub 2} sample was 3.44 eV, higher than bulk CeO{sub 2} powder (E{sub g} = 3.19 eV) due to the quantum confinement effect. Optical and electrochemical characteristics indicated that the electrical properties of PANI/CeO{sub 2} hybrid nanocomposite film are dominated by PANI doping. (semiconductor materials)

  20. Method of passivating semiconductor surfaces

    Science.gov (United States)

    Wanlass, Mark W.

    1990-01-01

    A method of passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

  1. Photon detector composed of metal and semiconductor nanoparticles

    International Nuclear Information System (INIS)

    Applying the function of the single electron transistor, a novel photon detector consisting of a self-assembled structure of metal and semiconductor nanoparticles and an organic insulating layer was developed. It showed coulomb blockade behavior under dark conditions and remarkable increase in current corresponding to light intensity under light irradiation. Ultraweak photon emission of about 600 counts per second in the ultraviolet region could be detected at room temperature by this photon counter

  2. Magnetic Nanocomposite Cilia Tactile Sensor

    KAUST Repository

    Alfadhel, Ahmed

    2015-10-21

    A multifunctional biomimetic nanocomposite tactile sensor is developed that can detect shear and vertical forces, feel texture, and measure flow with extremely low power consumption. The sensor\\'s high performance is maintained within a wide operating range that can be easily adjusted. The concept works on rigid and flexible substrates and the sensors can be used in air or water without any modifications.

  3. Percolation Threshold in Polycarbonate Nanocomposites

    Science.gov (United States)

    Ahuja, Suresh

    2014-03-01

    Nanocomposites have unique mechanical, electrical, magnetic, optical and thermal properties. Many methods could be applied to prepare polymer-inorganic nanocomposites, such as sol-gel processing, in-situ polymerization, particle in-situ formation, blending, and radiation synthesis. The analytical composite models that have been put forth include Voigt and Reuss bounds, Polymer nanocomposites offer the possibility of substantial improvements in material properties such as shear and bulk modulus, yield strength, toughness, film scratch resistance, optical properties, electrical conductivity, gas and solvent transport, with only very small amounts of nanoparticles Experimental results are compared against composite models of Hashin and Shtrikman bounds, Halpin-Tsai model, Cox model, and various Mori and Tanaka models. Examples of numerical modeling are molecular dynamics modeling and finite element modeling of reduced modulus and hardness that takes into account the modulus of the components and the effect of the interface between the hard filler and relatively soft polymer, polycarbonate. Higher nanoparticle concentration results in poor dispersion and adhesion to polymer matrix which results in lower modulus and hardness and departure from the existing composite models. As the level of silica increases beyond a threshold level, aggregates form which results in weakening of the structure. Polymer silica interface is found to be weak as silica is non-interacting promoting interfacial slip at silica-matrix junctions. Our experimental results compare favorably with those of nanocomposites of polyesters where the effect of nanoclay on composite hardness and modulus depended on dispersion of nanoclay in polyester.

  4. Optical properties of polymer nanocomposites

    Indian Academy of Sciences (India)

    S Srivastava; M Haridas; J K Basu

    2008-06-01

    Nanomaterials have emerged as an area of interest motivated by potential applications of these materials in light emitting diodes, solar cells, polarizers, light – stable colour filters, optical sensors, optical data communication and optical data storage. Nanomaterials are of particular interest as they combine the properties of two or more different materials with the possibility of possessing novel mechanical, electronic or chemical behaviour. Understanding and tuning such effects could lead to hybrid devices based on these nanocomposites with improved optical properties. We have prepared polymer nanocomposites of well-defined compositions and studied the optical properties of powders and their thin films. UV-vis absorption spectroscopy on nanocomposite powders and spectroscopic ellipsometry measurements on thin films was used to study the effect of interfacial morphology, interparticle spacing and finite size effects on optical properties of nanocomposites. Systematic shift in the imaginary part of the dielectric function can be seen with variation in size and fraction of the gold nanoparticle. The thickness of the film also plays a significant role in the tunability of the optical spectra.

  5. High performance thermoelectric nanocomposite device

    Science.gov (United States)

    Yang, Jihui; Snyder, Dexter D.

    2011-10-25

    A thermoelectric device includes a nanocomposite material with nanowires of at least one thermoelectric material having a predetermined figure of merit, the nanowires being formed in a porous substrate having a low thermal conductivity and having an average pore diameter ranging from about 4 nm to about 300 nm.

  6. Physics of Organic Semiconductors

    CERN Document Server

    Brütting, Wolfgang

    2005-01-01

    Filling the gap in the literature currently available, this book presents an overview of our knowledge of the physics behind organic semiconductor devices. Contributions from 18 international research groups cover various aspects of this field, ranging from the growth of organic layers and crystals, their electronic properties at interfaces, their photophysics and electrical transport properties to the application of these materials in such different devices as organic field-effect transistors, photovoltaic cells and organic light-emitting diodes. From the contents:. * Excitation Dynamics in O

  7. Band structure of semiconductors

    CERN Document Server

    Tsidilkovski, I M

    2013-01-01

    Band Structure of Semiconductors provides a review of the theoretical and experimental methods of investigating band structure and an analysis of the results of the developments in this field. The book presents the problems, methods, and applications in the study of band structure. Topics on the computational methods of band structure; band structures of important semiconducting materials; behavior of an electron in a perturbed periodic field; effective masses and g-factors for the most commonly encountered band structures; and the treatment of cyclotron resonance, Shubnikov-de Haas oscillatio

  8. Layered semiconductor neutron detectors

    Science.gov (United States)

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  9. Hydrogen in semiconductors

    CERN Document Server

    Pankove, Jacques I

    1991-01-01

    Hydrogen plays an important role in silicon technology, having a profound effect on a wide range of properties. Thus, the study of hydrogen in semiconductors has received much attention from an interdisciplinary assortment of researchers. This sixteen-chapter volume provides a comprehensive review of the field, including a discussion of hydrogenation methods, the use of hydrogen to passivate defects, the use of hydrogen to neutralize deep levels, shallow acceptors and shallow donors in silicon, vibrational spectroscopy, and hydrogen-induced defects in silicon. In addition to this detailed cove

  10. Basic properties of semiconductors

    CERN Document Server

    Landsberg, PT

    2013-01-01

    Since Volume 1 was published in 1982, the centres of interest in the basic physics of semiconductors have shifted. Volume 1 was called Band Theory and Transport Properties in the first edition, but the subject has broadened to such an extent that Basic Properties is now a more suitable title. Seven chapters have been rewritten by the original authors. However, twelve chapters are essentially new, with the bulk of this work being devoted to important current topics which give this volume an almost encyclopaedic form. The first three chapters discuss various aspects of modern band theory and the

  11. Semiconductor microcavity polaritons

    Energy Technology Data Exchange (ETDEWEB)

    Vinogradov, Evgenii A [Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow region (Russian Federation)

    2002-12-31

    The optical properties of wide-gap semiconductor films on metal substrates were investigated experimentally by infrared spectroscopy, Raman scattering, and femtosecond spectroscopy techniques as well as theoretically in the framework of linear crystal optics. The optical spectra of such planar structures (microresonators) were shown to bear information on electromagnetic excitations of both the surface and the volume of the structure. The optical spectra are determined by the interaction of all dipole-active excitations of the component materials with the electromagnetic modes of the microresonator, which in turn are determined by the permittivities of each component material, microcavity (microresonator) thickness, and the experimental conditions. (reviews of topical problems)

  12. Isotopically controlled semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Haller, Eugene E.

    2001-12-21

    Semiconductor bulk crystals and multilayer structures with controlled isotopic composition have attracted much scientific and technical interest in the past few years. Isotopic composition affects a large number of physical properties, including phonon energies and lifetimes, bandgaps, the thermal conductivity and expansion coefficient and spin-related effects. Isotope superlattices are ideal media for self-diffusion studies. In combination with neutron transmutation doping, isotope control offers a novel approach to metal-insulator transition studies. Spintronics, quantum computing and nanoparticle science are emerging fields using isotope control.

  13. Synergistic effect of Ag nanoparticle-decorated graphene oxide and carbon fiber on electrical actuation of polymeric shape memory nanocomposites

    Science.gov (United States)

    Lu, Haibao; Liang, Fei; Gou, Jihua; Leng, Jinsong; Du, Shanyi

    2014-08-01

    This study reports an effective approach of significantly improving electrical properties and recovery performance of shape memory polymer (SMP) nanocomposite, of which its shape recovery was triggered by electrically resistive Joule heating. Reduced graphene oxide (GOs) self-assembled and grafted onto carbon fiber, were used to enhance the interfacial bonding with the SMP matrix via van der Waals force and covalent bond, respectively. A layer of Ag nanoparticles was synthesized from Ag+ solution and chemically deposited onto GO assemblies. These Ag nanoparticles were expected to bridge the gap between GO and improve the electrical conductivity. The experimental results reveal that the electrical conductivity of the SMP nanocomposite was significantly improved via the synergistic effect between Ag nanoparticle-decorated GO and carbon fiber. Finally, the electrically induced shape memory effect of the SMP nanocomposite was achieved, and the temperature distribution in the SMP nanocomposites was recorded and monitored. An effective approach was demonstrated to produce the electro-activated SMP nanocomposites and the resistive Joule heating was viable at a low electrical voltage below 10 V.

  14. Synergistic effect of Ag nanoparticle-decorated graphene oxide and carbon fiber on electrical actuation of polymeric shape memory nanocomposites

    International Nuclear Information System (INIS)

    This study reports an effective approach of significantly improving electrical properties and recovery performance of shape memory polymer (SMP) nanocomposite, of which its shape recovery was triggered by electrically resistive Joule heating. Reduced graphene oxide (GOs) self-assembled and grafted onto carbon fiber, were used to enhance the interfacial bonding with the SMP matrix via van der Waals force and covalent bond, respectively. A layer of Ag nanoparticles was synthesized from Ag+ solution and chemically deposited onto GO assemblies. These Ag nanoparticles were expected to bridge the gap between GO and improve the electrical conductivity. The experimental results reveal that the electrical conductivity of the SMP nanocomposite was significantly improved via the synergistic effect between Ag nanoparticle-decorated GO and carbon fiber. Finally, the electrically induced shape memory effect of the SMP nanocomposite was achieved, and the temperature distribution in the SMP nanocomposites was recorded and monitored. An effective approach was demonstrated to produce the electro-activated SMP nanocomposites and the resistive Joule heating was viable at a low electrical voltage below 10 V. (paper)

  15. Comparative study of nanocomposites prepared by pulsed and dc sputtering combined with plasma polymerization suitable for photovoltaic device applications

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Amreen A. [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Pal, Arup R., E-mail: arpal@iasst.gov.in [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Kar, Rajib [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai (India); Bailung, Heremba; Chutia, Joyanti [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Patil, Dinkar S. [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai (India)

    2014-12-15

    Plasma processing, a single step method for production of large area composite films, is employed to deposit plasma polymerized aniline-Titanium dioxide (PPani-TiO{sub 2}) nanocomposite thin films. The deposition of PPani-TiO{sub 2} nanocomposite films are made using reactive magnetron sputtering and plasma polymerization combined process. This study focuses on the direct comparison between continuous and pulsed dc magnetron sputtering techniques of titanium in combination with rf plasma polymerization of aniline. The deposited PPani-TiO{sub 2} nanocomposite films are characterized and discussed in terms of structural, morphological and optical properties. A self powered hybrid photodetector has been developed by plasma based process. The proposed method provides a new route where the self-assembly of molecules, that is, the spontaneous association of atomic or molecular building blocks under plasma environment, emerge as a successful strategy to form well-defined structural and morphological units of nanometer dimensions. - Highlights: • PPani-TiO{sub 2} nanocomposite by pulsed and dc sputtering with rf plasma polymerization. • In-situ and Ex-situ H{sub 2}SO{sub 4} doping in PPani-TiO{sub 2} nanocomposite. • PPani-TiO{sub 2} nanocomposite based self-powered-hybrid photodetector.

  16. Semiconductor Laser with Aperiodic Photonic Lattice

    OpenAIRE

    Subhasish Chakraborty

    2008-01-01

    A semiconductor laser and method for selecting laser frequency emission from the semiconductor laser are disclosed. The semiconductor laser provides selectable frequency emission and includes an aperiodic photonic lattice.

  17. Semiconductor devices incorporating multilayer interference regions

    Science.gov (United States)

    Biefeld, Robert M.; Drummond, Timothy J.; Gourley, Paul L.; Zipperian, Thomas E.

    1990-01-01

    A semiconductor high reflector comprising a number of thin alternating layers of semiconductor materials is electrically tunable and may be used as a temperature insensitive semiconductor laser in a Fabry-Perot configuration.

  18. Doping semiconductor nanocrystals.

    Science.gov (United States)

    Erwin, Steven C; Zu, Lijun; Haftel, Michael I; Efros, Alexander L; Kennedy, Thomas A; Norris, David J

    2005-07-01

    Doping--the intentional introduction of impurities into a material--is fundamental to controlling the properties of bulk semiconductors. This has stimulated similar efforts to dope semiconductor nanocrystals. Despite some successes, many of these efforts have failed, for reasons that remain unclear. For example, Mn can be incorporated into nanocrystals of CdS and ZnSe (refs 7-9), but not into CdSe (ref. 12)--despite comparable bulk solubilities of near 50 per cent. These difficulties, which have hindered development of new nanocrystalline materials, are often attributed to 'self-purification', an allegedly intrinsic mechanism whereby impurities are expelled. Here we show instead that the underlying mechanism that controls doping is the initial adsorption of impurities on the nanocrystal surface during growth. We find that adsorption--and therefore doping efficiency--is determined by three main factors: surface morphology, nanocrystal shape, and surfactants in the growth solution. Calculated Mn adsorption energies and equilibrium shapes for several nanocrystals lead to specific doping predictions. These are confirmed by measuring how the Mn concentration in ZnSe varies with nanocrystal size and shape. Finally, we use our predictions to incorporate Mn into previously undopable CdSe nanocrystals. This success establishes that earlier difficulties with doping are not intrinsic, and suggests that a variety of doped nanocrystals--for applications from solar cells to spintronics--can be anticipated. PMID:16001066

  19. Squeezed light in semiconductors

    CERN Document Server

    Ward, M B

    2001-01-01

    Experimental evidence is presented for the generation of photon-number squeezed states of light as a result of multi-photon absorption. Photon-number squeezing as a result of non-linear absorption has long been predicted and results have been obtained utilising two very different material systems: (i) an AIGaAs waveguide in which high optical intensities can be maintained over a relatively long interaction length of 2 mm; (ii) the organic polymer p-toluene sulphonate polydiacetylene that is essentially a one-dimensional semiconductor possessing a highly nonlinear optical susceptibility. The resulting nonlinear absorption is shown to leave the transmitted light in a state that is clearly nonclassical, exhibiting photon-number fluctuations below the shot-noise limit. Tuning the laser wavelength across the half-bandgap energy has enabled a comparison between two- and three-photon processes in the semiconductor waveguide. The correlations created between different spectral components of a pulsed beam of light as ...

  20. Polyamide blend-based nanocomposites: A review

    Directory of Open Access Journals (Sweden)

    W. S. Chow

    2015-03-01

    Full Text Available Polymer blend nanocomposites have been considered as a stimulating route for creating a new type of high performance material that combines the advantages of polymer blends and the merits of polymer nanocomposites. In nanocomposites with multiphase matrices, the concept of using nanofillers to improve select properties (e.g., mechanical, thermal, chemical, etc of a polymer blend, as well as to modify and stabilize the blend morphology has received a great deal of interest. This review reports recent advances in the field of polyamide (PA blend-based nanocomposites. Emphasis is placed on the PA-rich blends produced by blending with other thermoplastics in the presence of nanofillers. The processing and properties of PA blend-based nanocomposites with nanofillers are discussed. In addition, the mechanical properties and morphology changes of PA blends with the incorporation of nanofillers are described. The issues of compatibility and toughening of PA blend nanocomposites are discussed, and current challenges are highlighted.

  1. Hydration and dynamic state of nanoconfined polymer layers govern toughness in nacre-mimetic nanocomposites.

    Science.gov (United States)

    Verho, Tuukka; Karesoja, Mikko; Das, Paramita; Martikainen, Lahja; Lund, Reidar; Alegría, Angel; Walther, Andreas; Ikkala, Olli

    2013-09-25

    Biological high-performance composites inspire to create new tough, strong, and stiff structural materials. We show a brittle-to-ductile transition in a self-assembled nacre-inspired poly(vinyl alcohol)/nanoclay composite based on a hydration-induced glass-to-rubber transition in the 2D-nanoconfined poly(vinyl alcohol) layers. The findings open routes to design dissipative toughening mechanisms to combine stiffness and strength in nanocomposites. PMID:23913740

  2. Quantum transport in semiconductor nanowires

    NARCIS (Netherlands)

    Van Dam, J.

    2006-01-01

    This thesis describes a series of experiments aimed at understanding the low-temperature electrical transport properties of semiconductor nanowires. The semiconductor nanowires (1-100 nm in diameter) are grown from nanoscale gold particles via a chemical process called vapor-liquid-solid (VLS) growt

  3. Semiconductor nanostructures in biological applications

    Energy Technology Data Exchange (ETDEWEB)

    Alexson, Dimitri [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Chen Hongfeng [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Cho, Michael [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States); Dutta, Mitra [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States); Li Yang [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Shi, Peng [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Raichura, Amit [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Ramadurai, Dinakar [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Parikh, Shaunak [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Stroscio, Michael A [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States); Vasudev, Milana [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States)

    2005-07-06

    Semiconductor nanostructures in biological applications are discussed. Results are presented on the use of colloidal semiconductor quantum dots both as biological tags and as structures that interact with and influence biomolecules. Results are presented on the use of semiconducting carbon nanotubes in biological applications. (topical review)

  4. Variable temperature semiconductor film deposition

    Science.gov (United States)

    Li, Xiaonan; Sheldon, Peter

    1998-01-01

    A method of depositing a semiconductor material on a substrate. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  5. II-VI semiconductor compounds

    CERN Document Server

    1993-01-01

    For condensed matter physicists and electronic engineers, this volume deals with aspects of II-VI semiconductor compounds. Areas covered include devices and applications of II-VI compounds; Co-based II-IV semi-magnetic semiconductors; and electronic structure of strained II-VI superlattices.

  6. Nanocomposite organomineral hybrid materials. Part 2

    OpenAIRE

    KUDRYAVTSEV Pavel Gennadievich; FIGOVSKY Oleg Lvovich

    2016-01-01

    The paper addresses the issues of alkoxide method of sol-gel synthesis and non-hydrolytic method of sol-gel synthesis and colloidal method of sol-gel synthesis. The authors also consider an alternative approach based on the use of soluble silicates as precursors in the sol-gel technology, of nanocomposites. It was shown that nanocomposites can be produced through aerogels. The paper also analyzes the mixing technologies of nanocomposites preparation. It has been demonstrated the possibility t...

  7. Nanocomposite organomineral hybrid materials. Part I

    OpenAIRE

    KUDRYAVTSEV Pavel Gennadievich; FIGOVSKY Oleg Lvovich

    2016-01-01

    The paper addresses the issues of alkoxide method of sol-gel synthesis and non-hydrolytic method of sol-gel synthesis and colloidal method of sol-gel synthesis. The authors also consider an alternative approach based on the use of soluble silicates as precursors in the sol-gel technology, of nanocomposites. It was shown that nanocomposites can be produced through aerogels. The paper also analyzes the mixing technologies of nanocomposites preparation. It has been demonstrated the possibility t...

  8. Polymer-phyllosilicate nanocomposites and their preparation

    Science.gov (United States)

    Chaiko, David J.

    2007-01-09

    Polymer-phyllosilicate nanocomposites that exhibit superior properties compared to the polymer alone, and methods-for producing these polymer-phyllosilicate nanocomposites, are provided. Polymeric surfactant compatabilizers are adsorbed onto the surface of hydrophilic or natural phyllosilicates to facilitate the dispersal and exfoliation of the phyllosilicate in a polymer matrix. Utilizing polymeric glycol based surfactants, polymeric dicarboxylic acids, polymeric diammonium surfactants, and polymeric diamine surfactants as compatabilizers facilitates natural phyllosilicate and hydrophilic organoclay dispersal in a polymer matrix to produce nanocomposites.

  9. Facile synthesis of SnO2-PbS nanocomposites with controlled structure for applications in photocatalysis

    Science.gov (United States)

    Kar, Arik; Sain, Sumanta; Rossouw, David; Knappett, Benjamin R.; Pradhan, Swapan Kumar; Wheatley, Andrew E. H.

    2016-01-01

    Recent studies have shown that SnO2-based nanocomposites offer excellent electrical, optical, and electrochemical properties. In this article, we present the facile and cost-effective fabrication, characterization and testing of a new SnO2-PbS nanocomposite photocatalyst designed to overcome low photocatalytic efficiency brought about by electron-hole recombination and narrow photoresponse range. The structure is fully elucidated by X-ray diffraction (XRD)/Reitveld refinement, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area analysis, and transmission electron microscopy (TEM). Energy-dispersive X-ray spectroscopy (EDX) spectrum imaging analysis demonstrates the intermixing of SnO2 and PbS to form nanocomposites. A charge separation mechanism is presented that explains how the two semiconductors in junction function synergistically. The efficacy of this new nanocomposite material in the photocatalytic degradation of the toxic dye Rhodamine B under simulated solar irradiation is demonstrated. An apparent quantum yield of 0.217 mol min-1 W-1 is calculated with data revealing good catalyst recyclability and that charge separation in SnO2-PbS leads to significantly enhanced photocatalytic activity in comparison to either SnO2 or PbS.Recent studies have shown that SnO2-based nanocomposites offer excellent electrical, optical, and electrochemical properties. In this article, we present the facile and cost-effective fabrication, characterization and testing of a new SnO2-PbS nanocomposite photocatalyst designed to overcome low photocatalytic efficiency brought about by electron-hole recombination and narrow photoresponse range. The structure is fully elucidated by X-ray diffraction (XRD)/Reitveld refinement, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area analysis, and transmission electron microscopy (TEM). Energy-dispersive X-ray spectroscopy (EDX) spectrum imaging

  10. Visible Light Photocatalysis via CdS/TiO2 Nanocomposite Materials

    Directory of Open Access Journals (Sweden)

    Elias K. Stefanakos

    2006-10-01

    Full Text Available Nanostructured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers, and selective reduction/oxidation of different classes of organic compounds. In the present paper, we have carried out a systematic synthesis of nanostructured CdS-TiO2 via reverse micelle process. The structural and microstructural characterizations of the as-prepared CdS-TiO2 nanocomposites are determined using XRD and SEM-EDS techniques. The visible light assisted photocatalytic performance is monitored by means of degradation of phenol in water suspension.

  11. Organic semiconductors in a spin

    CERN Document Server

    Samuel, I

    2002-01-01

    A little palladium can go a long way in polymer-based light-emitting diodes. Inorganic semiconductors such as silicon and gallium arsenide are essential for countless applications in everyday life, ranging from PCs to CD players. However, while they offer unrivalled computational speed, inorganic semiconductors are also rigid and brittle, which means that they are less suited to applications such as displays and flexible electronics. A completely different class of materials - organic semiconductors - are being developed for these applications. Organic semiconductors have many attractive features: they are easy to make, they can emit visible light, and there is tremendous scope for tailoring their properties to specific applications by changing their chemical structure. Research groups and companies around the world have developed a wide range of organic-semiconductor devices, including transistors, light-emitting diodes (LEDs), solar cells and lasers. (U.K.)

  12. Mass Transfer in Amperometric Biosensors Based on Nanocomposite Thin Films of Redox Polymers and Oxidoreductases

    Directory of Open Access Journals (Sweden)

    Aleksandr L. Simonian

    2002-03-01

    Full Text Available Mass transfer in nanocomposite hydrogel thin films consisting of alternating layers of an organometallic redox polymer (RP and oxidoreductase enzymes was investigated. Multilayer nanostructures were fabricated on gold surfaces by the deposition of an anionic self-assembled monolayer of 11-mercaptoundecanoic acid, followed by the electrostatic binding of a cationic redox polymer, poly[vinylpyridine Os(bis-bipyridine2Clco-allylamine], and an anionic oxidoreductase. Surface plasmon resonance spectroscopy, Fourier transform infrared external reflection spectroscopy (FTIR-ERS, ellipsometry and electrochemistry were employed to characterize the assembly of these nanocomposite films. Simultaneous SPR/electrochemistry enabled real time observation of the assembly of sensing components, changes in film structure with electrode potential, and the immediate, in situ electrochemical verification of substrate-dependent current upon the addition of enzyme to the multilayer structure. SPR and FTIR-ERS studies also showed no desorption of polymer or enzyme from the nanocomposite structure when stored in aqueous environment occurred over the period of three weeks, suggesting that decreasing in substrate sensitivity were due to loss of enzymatic activity rather than loss of film compounds from the nanostructure.

  13. Graphene oxide-silica nanohybrids as fillers for PA6 based nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Maio, A. [Department of Civil, Environmental, Aerospace, Materials Engineering, University of Palermo, Viale delle Scienze, Ed. 6, 90128, Palermo, Italy and STEBICEF, Section of Biology and Chemistry, University of Palermo, Viale delle Scienze, Parco d' Orleans (Italy); Fucarino, R.; Khatibi, R. [Dipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica, University of Palermo, Viale delle Scienze, Ed. 6, 90128, Palermo (Italy); Botta, L.; Scaffaro, R. [Department of Civil, Environmental, Aerospace, Materials Engineering, University of Palermo, Viale delle Scienze, Ed. 6, 90128, Palermo (Italy); Rosselli, S.; Bruno, M. [STEBICEF, Section of Biology and Chemistry, University of Palermo, Viale delle Scienze, Parco d' Orleans II, 90128 Palermo (Italy)

    2014-05-15

    Graphene oxide (GO) was prepared by oxidation of graphite flakes by a mixture of H{sub 2}SO{sub 4}/H{sub 3}PO{sub 4} and KMnO{sub 4} based on Marcano's method. Two different masterbatches containing GO (33.3%) and polyamide-6 (PA6) (66.7%) were prepared both via solvent casting in formic acid and by melt mixing in a mini-extruder (Haake). The two masterbatches were then used to prepare PA6-based nanocomposites with a content of 2% in GO. For comparison, a nanocomposite by direct mixing of PA6 and GO (2%) and PA6/graphite nanocomposites were prepared, too. The oxidation of graphite into GO was assessed by X-ray diffraction (XRD), Micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) analyses. All these techniques demonstrated the effectiveness of the graphite modification, since the results put into evidence that, after the acid treatment, interlayer distance, oxygen content and defects increased. SEM micrographs carried out on the nanocomposites, showed GO layers totally surrounded by polyamide-6, this feature is likely due to the strong interaction between the hydrophilic moieties located both on GO and on PA6. On the contrary, no interactions were observed when graphite was used as filler. Mechanical characterization, carried out by tensile and dynamic-mechanical tests, marked an improvement of the mechanical properties observed. Photoluminescence and EPR measurements were carried out onto nanoparticles and nanocomposites to study the nature of the interactions and to assess the possibility to use this class of materials as semiconductors or optical sensors.

  14. Synthesis, characterization and multifunctional properties of plasmonic Ag-TiO2 nanocomposites.

    Science.gov (United States)

    Prakash, Jai; Kumar, Promod; Harris, R A; Swart, Chantel; Neethling, J H; van Vuuren, A Janse; Swart, H C

    2016-09-01

    We report on the synthesis of multifunctional Ag-TiO2 nanocomposites and their optical, physio-chemical, surface enhanced Raman scattering (SERS) and antibacterial properties. A series of Ag-TiO2 nanocomposites were synthesized by sol-gel technique and characterized by x-ray diffraction, scanning and transmission electron microscopy, energy-dispersed x-ray analysis, photoluminescence, UV-vis, x-ray photoelectron and Raman spectroscopy and Brunauer-Emmett-Teller method. The Ag nanoparticles (NPs) (7-20 nm) were found to be uniformly distributed around and strongly attached to TiO2 NPs. The novel optical responses of the nanocomposites are due to the strong electric field from the localized surface plasmon (LSP) excitation of the Ag NPs and decreased recombination of photo-induced electrons and holes at Ag-TiO2 interface providing potential materials for photocatalysis. The nanocomposites show enhancement in the SERS signals of methyl orange (MO) molecules with increasing Ag content attributed to the long-range electromagnetic enhancement from the excited LSP of the Ag NPs. To further understand the SERS activity, molecular mechanics and molecular dynamics simulations were used to study the geometries and SERS enhancement of MO adsorbed onto Ag-TiO2 respectively. Simulation results indicate that number of ligands (MO) that adsorb onto the Ag NPs as well as binding energy per ligand increases with increasing NP density and molecule-to-surface orientation is mainly flat resulting in strong bond strength between MO and Ag NP surface and enhanced SERS signals. The antimicrobial activity of the Ag-TiO2 nanocomposites was tested against the bacterium Staphylococcus aureus and enhanced antibacterial effect was observed with increasing Ag content explained by contact killing action mechanism. These results foresee promising applications of the plasmonic metal-semiconductor based nano-biocomposites for both chemical and biological samples. PMID:27456278

  15. Synthesis, characterization and multifunctional properties of plasmonic Ag-TiO2 nanocomposites

    Science.gov (United States)

    Prakash, Jai; Kumar, Promod; Harris, R. A.; Swart, Chantel; Neethling, J. H.; Janse van Vuuren, A.; Swart, H. C.

    2016-09-01

    We report on the synthesis of multifunctional Ag-TiO2 nanocomposites and their optical, physio-chemical, surface enhanced Raman scattering (SERS) and antibacterial properties. A series of Ag-TiO2 nanocomposites were synthesized by sol-gel technique and characterized by x-ray diffraction, scanning and transmission electron microscopy, energy-dispersed x-ray analysis, photoluminescence, UV-vis, x-ray photoelectron and Raman spectroscopy and Brunauer-Emmett-Teller method. The Ag nanoparticles (NPs) (7-20 nm) were found to be uniformly distributed around and strongly attached to TiO2 NPs. The novel optical responses of the nanocomposites are due to the strong electric field from the localized surface plasmon (LSP) excitation of the Ag NPs and decreased recombination of photo-induced electrons and holes at Ag-TiO2 interface providing potential materials for photocatalysis. The nanocomposites show enhancement in the SERS signals of methyl orange (MO) molecules with increasing Ag content attributed to the long-range electromagnetic enhancement from the excited LSP of the Ag NPs. To further understand the SERS activity, molecular mechanics and molecular dynamics simulations were used to study the geometries and SERS enhancement of MO adsorbed onto Ag-TiO2 respectively. Simulation results indicate that number of ligands (MO) that adsorb onto the Ag NPs as well as binding energy per ligand increases with increasing NP density and molecule-to-surface orientation is mainly flat resulting in strong bond strength between MO and Ag NP surface and enhanced SERS signals. The antimicrobial activity of the Ag-TiO2 nanocomposites was tested against the bacterium Staphylococcus aureus and enhanced antibacterial effect was observed with increasing Ag content explained by contact killing action mechanism. These results foresee promising applications of the plasmonic metal-semiconductor based nano-biocomposites for both chemical and biological samples.

  16. Synthesis and characteristics of multifunctional Fe3O4-SiO2-CdS magnetic-fluorescent nanocomposites

    Institute of Scientific and Technical Information of China (English)

    Zhang Ri-Chen; Liu Ling; Xu Xiao-Liang

    2011-01-01

    A luminescent superparamagnetic nanocomposite with an Fe3O4-SiO2-CdS structure is synthesised.Coated with a silica shell,Fe3O4 nanoparticles and CdS quantum dots(QDs)are successfully assembled together.Analysed from the test results of X-ray diffraction(XRD),transmission electron microscopy(TEM),high resolution transimission electron microscopy(HRTEM),hysteresis loop,and photoluminescence(PL)spectrum,these nanocomposites exhibit superparamagnetic and photoluminescent properties.

  17. Packaging and Performance of 980nm Broad Area Semiconductor Lasers

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    High power broad area semiconductor lasers have found increasing applications in pumping of solid state laser systems and fiber amplifiers, frequency doubling, medical systems and material processing.Packaging including the assembly design, process and thermal management, has a significant impact on the optical performance and reliability of a high power broad area laser. In this paper, we introduce the package structures and assembling process of 980nm broad area lasers and report the performances including output power, thermal behavior and far fields.We will report two types of high power broad area laser assemblies.One is a microchannel liquid cooled assembly and the other is a conduction cooled CT-mount assembly. Optical powers of 15W and 10W were achieved from a 980nm broad area laser with a 120 μ m stripe width in a microchannel liquid cooled assembly and conduction cooled CT-mount assembly, respectively.Furthermore,a high power of 6.5W out of fiber was demonstrated from a pigtailed, fully packaged butterfly-type module without TEC (Thermoelectric cooler).The measurement results showed that thermal management is the key in not only improving output power, but also significantly improving beam divergence and far field distribution.The results also showed that the die attach solder can significant impact the reliability of high power broad area lasers and that indium solder is not suitable for high power laser applications due to electromigration at high current densities and high temperatures.

  18. Furnace assembly

    Science.gov (United States)

    Panayotou, Nicholas F.; Green, Donald R.; Price, Larry S.

    1985-01-01

    A method of and apparatus for heating test specimens to desired elevated temperatures for irradiation by a high energy neutron source. A furnace assembly is provided for heating two separate groups of specimens to substantially different, elevated, isothermal temperatures in a high vacuum environment while positioning the two specimen groups symmetrically at equivalent neutron irradiating positions.

  19. Quantum Dot/Liquid Crystal Nanocomposites in Photonic Devices

    Directory of Open Access Journals (Sweden)

    Andrea L. Rodarte

    2015-07-01

    Full Text Available Quantum dot/liquid crystal nano-composites are promising new materials for a variety of applications in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however, we need to control and stabilize nano-particle dispersion in different liquid crystal host phases and understand how the particles behave in an anisotropic fluid. An ideal system will allow for the controlled assembly of either well-defined nano-particle clusters or a uniform particle distribution. In this paper, we investigate mesogen-functionalized quantum dots for dispersion in cholesteric liquid crystal. These nanoparticles are known to assemble into dense stable packings in the nematic phase, and such structures, when localized in the liquid crystal defects, can potentially enhance the coupling between particles and a cholesteric cavity. Controlling the dispersion and assembly of quantum dots using mesogenic surface ligands, we demonstrate how resonant fluid photonic cavities can result from the co-assembly of luminescent nanoparticles in the presence of cholesteric liquid crystalline ordering.

  20. Semiconductor nanowire lasers

    Science.gov (United States)

    Eaton, Samuel W.; Fu, Anthony; Wong, Andrew B.; Ning, Cun-Zheng; Yang, Peidong

    2016-06-01

    The discovery and continued development of the laser has revolutionized both science and industry. The advent of miniaturized, semiconductor lasers has made this technology an integral part of everyday life. Exciting research continues with a new focus on nanowire lasers because of their great potential in the field of optoelectronics. In this Review, we explore the latest advancements in the development of nanowire lasers and offer our perspective on future improvements and trends. We discuss fundamental material considerations and the latest, most effective materials for nanowire lasers. A discussion of novel cavity designs and amplification methods is followed by some of the latest work on surface plasmon polariton nanowire lasers. Finally, exciting new reports of electrically pumped nanowire lasers with the potential for integrated optoelectronic applications are described.

  1. Semiconductor Nanomaterials and Nanocrystals

    Directory of Open Access Journals (Sweden)

    N.V. Stetsyk

    2015-06-01

    Full Text Available This article introduces an innovative synthesis of doped nanocrystals and aims at expanding the fundamental understanding of charge transport in these doped nanocrystal films. The list of semiconductor nanocrystals that can be doped is large, and if one combines that with available dopants, an even larger set of materials with interesting properties and applications can be generated. In addition to doping, another promising route to increase conductivity in nanocrystal films is to use nanocrystals with high ionic conductivities. This work also examines this possibility by studying new phases of mixed ionic and electronic conductors at the nanoscale. Such a versatile approach may open new pathways for interesting fundamental research, and also lay the foundation for the creation of novel materials with important application.

  2. Semiconductor radiation detector

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Zane W. (Oak Ridge, TN); Burger, Arnold (Knoxville, TN)

    2010-03-30

    A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

  3. A semiconductor based electrode

    Energy Technology Data Exchange (ETDEWEB)

    Khamatani, A.; Kobayasi, K.

    1983-03-30

    The semiconductor electrode is submerged into an electrolyte which is held in the illuminated chamber. The other electrode is placed in a dark chamber connected with the channel to be illuminated, which has a partition in the form of a membrane. An electric current flows in the external circuit of the element with illumination of the first electrode. The illuminated electrode is covered with a thin film of a substance which is stable with the action of the electrolyte. The film is made of Si02, A1203, GaN or A1N. The protective coating makes it possible to use materials less stable than Ti02 in a rutile modification, but which have higher characteristics than the GaP, GaAs, CdS and InP, for making the electrode.

  4. Investigation of Light Induced Carrier Transport Phenomena Through ZnCdS Nanocomposite Based Schottky Diode

    Science.gov (United States)

    Das, Mrinmay; Middya, Somnath; Datta, Joydeep; Dey, Arka; Jana, Rajkumar; Layek, Animesh; Ray, Partha Pratim

    2016-08-01

    Here, we have discussed the electron transport phenomena through the interface formed by aluminium and hydrothermally synthesized Zinc-Cadmium-Sulphide (ZnCdS) nanocomposite. In this background, the structural, optical, and electrical characterization of the synthesized material were studied. The estimated optical band gap energy (=3.14 eV) and the room temperature conductivity (1.6 × 10-6 S cm-1) of the synthesized nanomaterial motivated us to explore the metal/inorganic-semiconductor interface. The carrier transport mechanism under dark and light-illuminated conditions was analyzed by the thermionic emission theory of the metal-semiconductor junction. Significant changes in rectification ratio, barrier potential, and the ideality factor were observed under light irradiance. The effect of incident radiation on mobility-lifetime ( μτ) product and the diffusion length ( L D) was demonstrated for the device.

  5. Investigation of Light Induced Carrier Transport Phenomena Through ZnCdS Nanocomposite Based Schottky Diode

    Science.gov (United States)

    Das, Mrinmay; Middya, Somnath; Datta, Joydeep; Dey, Arka; Jana, Rajkumar; Layek, Animesh; Ray, Partha Pratim

    2016-05-01

    Here, we have discussed the electron transport phenomena through the interface formed by aluminium and hydrothermally synthesized Zinc-Cadmium-Sulphide (ZnCdS) nanocomposite. In this background, the structural, optical, and electrical characterization of the synthesized material were studied. The estimated optical band gap energy (=3.14 eV) and the room temperature conductivity (1.6 × 10-6 S cm-1) of the synthesized nanomaterial motivated us to explore the metal/inorganic-semiconductor interface. The carrier transport mechanism under dark and light-illuminated conditions was analyzed by the thermionic emission theory of the metal-semiconductor junction. Significant changes in rectification ratio, barrier potential, and the ideality factor were observed under light irradiance. The effect of incident radiation on mobility-lifetime (μτ) product and the diffusion length (L D) was demonstrated for the device.

  6. Surface properties and photocatalytic activity of KTaO3, CdS, MoS2 semiconductors and their binary and ternary semiconductor composites.

    Science.gov (United States)

    Bajorowicz, Beata; Cybula, Anna; Winiarski, Michał J; Klimczuk, Tomasz; Zaleska, Adriana

    2014-01-01

    Single semiconductors such as KTaO3, CdS MoS2 or their precursor solutions were combined to form novel binary and ternary semiconductor nanocomposites by the calcination or by the hydro/solvothermal mixed solutions methods, respectively. The aim of this work was to study the influence of preparation method as well as type and amount of the composite components on the surface properties and photocatalytic activity of the new semiconducting photoactive materials. We presented different binary and ternary combinations of the above semiconductors for phenol and toluene photocatalytic degradation and characterized by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface area and porosity. The results showed that loading MoS2 onto CdS as well as loading CdS onto KTaO3 significantly enhanced absorption properties as compared with single semiconductors. The highest photocatalytic activity in phenol degradation reaction under both UV-Vis and visible light irradiation and very good stability in toluene removal was observed for ternary hybrid obtained by calcination of KTaO3, CdS, MoS2 powders at the 10:5:1 molar ratio. Enhanced photoactivity could be related to the two-photon excitation in KTaO3-CdS-MoS2 composite under UV-Vis and/or to additional presence of CdMoO4 working as co-catalyst.

  7. Electrospun Borneol-PVP Nanocomposites

    Directory of Open Access Journals (Sweden)

    Xiao-Yan Li

    2012-01-01

    Full Text Available The present work investigates the validity of electrospun borneol-polyvinylpyrrolidone (PVP nanocomposites in enhancing drug dissolution rates and improving drug physical stability. Based on hydrogen bonding interactions and via an electrospinning process, borneol and PVP can form stable nanofiber-based composites. FESEM observations demonstrate that composite nanofibers with uniform structure could be generated with a high content of borneol up to 33.3% (w/w. Borneol is well distributed in the PVP matrix molecularly to form the amorphous composites, as verified by DSC and XRD results. The composites can both enhance the dissolution profiles of borneol and increase its physical stability against sublimation for long-time storage by immobilization of borneol molecules with PVP. The incorporation of borneol in the PVP matrix weakens the tensile properties of nanofibers, and the mechanism is discussed. Electrospun nanocomposites can be alternative candidates for developing novel nano-drug delivery systems with high performance.

  8. Review: nanocomposites in food packaging.

    Science.gov (United States)

    Arora, Amit; Padua, G W

    2010-01-01

    The development of nanocomposites is a new strategy to improve physical properties of polymers, including mechanical strength, thermal stability, and gas barrier properties. The most promising nanoscale size fillers are montmorillonite and kaolinite clays. Graphite nanoplates are currently under study. In food packaging, a major emphasis is on the development of high barrier properties against the migration of oxygen, carbon dioxide, flavor compounds, and water vapor. Decreasing water vapor permeability is a critical issue in the development of biopolymers as sustainable packaging materials. The nanoscale plate morphology of clays and other fillers promotes the development of gas barrier properties. Several examples are cited. Challenges remain in increasing the compatibility between clays and polymers and reaching complete dispersion of nanoplates. Nanocomposites may advance the utilization of biopolymers in food packaging. PMID:20492194

  9. Multiscale modeling of polymer nanocomposites

    Science.gov (United States)

    Sheidaei, Azadeh

    In recent years, polymer nano-composites (PNCs) have increasingly gained more attention due to their improved mechanical, barrier, thermal, optical, electrical and biodegradable properties in comparison with the conventional micro-composites or pristine polymer. With a modest addition of nanoparticles (usually less than 5wt. %), PNCs offer a wide range of improvements in moduli, strength, heat resistance, biodegradability, as well as decrease in gas permeability and flammability. Although PNCs offer enormous opportunities to design novel material systems, development of an effective numerical modeling approach to predict their properties based on their complex multi-phase and multiscale structure is still at an early stage. Developing a computational framework to predict the mechanical properties of PNC is the focus of this dissertation. A computational framework has been developed to predict mechanical properties of polymer nano-composites. In chapter 1, a microstructure inspired material model has been developed based on statistical technique and this technique has been used to reconstruct the microstructure of Halloysite nanotube (HNT) polypropylene composite. This technique also has been used to reconstruct exfoliated Graphene nanoplatelet (xGnP) polymer composite. The model was able to successfully predict the material behavior obtained from experiment. Chapter 2 is the summary of the experimental work to support the numerical work. First, different processing techniques to make the polymer nanocomposites have been reviewed. Among them, melt extrusion followed by injection molding was used to manufacture high density polyethylene (HDPE)---xGnP nanocomposties. Scanning electron microscopy (SEM) also was performed to determine particle size and distribution and to examine fracture surfaces. Particle size was measured from these images and has been used for calculating the probability density function for GNPs in chapter 1. A series of nanoindentation tests have

  10. Magnetic Nanocomposite Cilia Energy Harvester

    KAUST Repository

    Khan, Mohammed Asadullah

    2016-02-11

    An energy harvester capable of converting low frequency vibrations into electrical energy is presented. The operating principle, fabrication process and output characteristics at different frequencies are discussed. The harvester is realized by fabricating an array of polydimethylsiloxane (PDMS) - iron nanowire nanocomposite cilia on a planar coil array. Each coil element consists of 14 turns and occupies an area of 600 μm x 600μm. The cilia are arranged in a 12x5 array and each cilium is 250 μm wide and 2 mm long. The magnetic characteristics of the fabricated cilia indicate that the nanowires are well aligned inside of the nanocomposite, increasing the efficiency of energy harvesting. The energy harvester occupies an area of 66.96 mm2 and produces an output r.m.s voltage of 206.47μV, when excited by a 40 Hz vibration of 1 mm amplitude.

  11. Fabrication de structures tridimensionnelles de nanocomposites polymeres charges de nanotubes de carbone a simple paroi

    Science.gov (United States)

    Laberge Lebel, Louis

    -covalent functionalization of the nanotubes by zinc protoporphyrin IX molecule and high shear mixing using a three-roll mill. The incorporation of the C-SWNTs into the resin led to an increase of the viscosity and the apparition of a shear thinning behaviour, characterized by capillary viscometry. The nanocomposite UV-curing behavior is characterized under differential scanning calorimetry coupled with a UV source. A further adjustment of the shear thinning behavior using fumed silica enabled the UV-DW fabrication of microbeams. Mechanical characterization reveals significant increase in both strength (by ˜64%) and modulus (by more than 15 times). These mechanical enhancements are attributed to both the covalent and the non-covalent functionalizations of the C-SWNTs. Nanocomposite spring networks composed of three micro-coils fabricated using the UV-DW technique are mechanically tested under compression and show a rigidity of ˜11.5 mN/mm. A micro-coil is also deposited between two uneven electrodes and a 10-6 S/cm electrical conductivity is measured. Nanocomposite scaffold structures are also deposited using the UV-DW technique. This thesis also reports the fabrication of 3D micro structured beams reinforced with the C-SWNT/polymer nanocomposite by using an approach based on the infiltration of 3D microfluidic networks. The 3D microfluidic network is first fabricated by the direct-write assembly method, which consists of the robotized deposition of fugitive ink filaments on an epoxy substrate, forming a 3D micro structured scaffold. After encapsulating the 3D micro-scaffold structure with an epoxy resin, the fugitive ink is liquefied and removed, resulting in a 3D network of interconnected microchannels. This microfluidic network is then infiltrated by the C-SWNT/polyurethane nanocomposite and subsequently cured. The final samples consist of rectangular beams having a complex 3D-skeleton structure of C-SWNT/polyrner nanocomposite fibers, adapted to offer better performance under flexural

  12. 3D Printing Functional Nanocomposites

    OpenAIRE

    Leong, Yew Juan

    2016-01-01

    3D printing presents the ability of rapid prototyping and rapid manufacturing. Techniques such as stereolithography (SLA) and fused deposition molding (FDM) have been developed and utilized since the inception of 3D printing. In such techniques, polymers represent the most commonly used material for 3D printing due to material properties such as thermo plasticity as well as its ability to be polymerized from monomers. Polymer nanocomposites are polymers with nanomaterials composited into the ...

  13. Silicone nanocomposite coatings for fabrics

    Science.gov (United States)

    Eberts, Kenneth (Inventor); Lee, Stein S. (Inventor); Singhal, Amit (Inventor); Ou, Runqing (Inventor)

    2011-01-01

    A silicone based coating for fabrics utilizing dual nanocomposite fillers providing enhanced mechanical and thermal properties to the silicone base. The first filler includes nanoclusters of polydimethylsiloxane (PDMS) and a metal oxide and a second filler of exfoliated clay nanoparticles. The coating is particularly suitable for inflatable fabrics used in several space, military, and consumer applications, including airbags, parachutes, rafts, boat sails, and inflatable shelters.

  14. Composite and Nanocomposite Metal Foams

    OpenAIRE

    Isabel Duarte; José M. F. Ferreira

    2016-01-01

    Open-cell and closed-cell metal foams have been reinforced with different kinds of micro- and nano-sized reinforcements to enhance their mechanical properties of the metallic matrix. The idea behind this is that the reinforcement will strengthen the matrix of the cell edges and cell walls and provide high strength and stiffness. This manuscript provides an updated overview of the different manufacturing processes of composite and nanocomposite metal foams.

  15. Composite and Nanocomposite Metal Foams

    Directory of Open Access Journals (Sweden)

    Isabel Duarte

    2016-01-01

    Full Text Available Open-cell and closed-cell metal foams have been reinforced with different kinds of micro- and nano-sized reinforcements to enhance their mechanical properties of the metallic matrix. The idea behind this is that the reinforcement will strengthen the matrix of the cell edges and cell walls and provide high strength and stiffness. This manuscript provides an updated overview of the different manufacturing processes of composite and nanocomposite metal foams.

  16. Nanocomposites for Vehicle Structural Applications

    OpenAIRE

    Njuguna, James; Silva, Francesco; Sachse, Sophia

    2011-01-01

    Advancements in the nanotechnology industry promise to offer improvements in capabilities across a spectrum of applications. This is of immense strategic importance to the high performance sector which has historically leveraged technological advances. The uses of polymer nanocomposites in structures have several predictable impacts on structural design and applications, primarily by providing a safer, faster, and eventually cheaper transportation in the future. In this chapter, special atten...

  17. Self-healing supramolecular nanocomposites

    OpenAIRE

    Liu, Z.

    2015-01-01

    The aim of this thesis is to execute a bottom-up design of the intrinsically self-healing nanocomposites. We briefly introduced the self-healing materials in chapter 1, covering classification and basic self-healing mechanism. In chapter 2, we have synthesized polyborosiloxane (PBS) according to the last century recipe as the self-healing supramolecular matrix. Additionally, we provided the long existing recipe with exclusive supplementary details, such as reaction kinetics, structural refine...

  18. Inorganic nanofluorides and related nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, Sergei V; Osiko, Vyacheslav V; Tkatchenko, E A; Fedorov, Pavel P [Laser Materials and Technologies Research Centre, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences (Russian Federation)

    2006-12-31

    The properties and prospects of application of fluoride nanoparticles are discussed. Pyrohydrolysis is considered as the key process determining the chemistry and technology of fluorides; its role increases on going to the nanosize region. The physical and chemical methods for the synthesis of fluoride nanoparticles, one- and two-dimensional nanoobjects as well as approaches to the preparation of nanocomposites (glass ceramics, heterovalent solid solutions with defect clusters, eutectoid composites, etc.) are analysed. Nanotechnology techniques used to produce heterogeneous nanoobjects are outlined.

  19. Inorganic nanofluorides and related nanocomposites

    Science.gov (United States)

    Kuznetsov, Sergei V.; Osiko, Vyacheslav V.; Tkatchenko, E. A.; Fedorov, Pavel P.

    2006-12-01

    The properties and prospects of application of fluoride nanoparticles are discussed. Pyrohydrolysis is considered as the key process determining the chemistry and technology of fluorides; its role increases on going to the nanosize region. The physical and chemical methods for the synthesis of fluoride nanoparticles, one- and two-dimensional nanoobjects as well as approaches to the preparation of nanocomposites (glass ceramics, heterovalent solid solutions with defect clusters, eutectoid composites, etc.) are analysed. Nanotechnology techniques used to produce heterogeneous nanoobjects are outlined.

  20. Semiconductor Nanocrystals for Biological Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Aihua; Gu, Weiwei; Larabell, Carolyn; Alivisatos, A. Paul

    2005-06-28

    Conventional organic fluorophores suffer from poor photo stability, narrow absorption spectra and broad emission feature. Semiconductor nanocrystals, on the other hand, are highly photo-stable with broad absorption spectra and narrow size-tunable emission spectra. Recent advances in the synthesis of these materials have resulted in bright, sensitive, extremely photo-stable and biocompatible semiconductor fluorophores. Commercial availability facilitates their application in a variety of unprecedented biological experiments, including multiplexed cellular imaging, long-term in vitro and in vivo labeling, deep tissue structure mapping and single particle investigation of dynamic cellular processes. Semiconductor nanocrystals are one of the first examples of nanotechnology enabling a new class of biomedical applications.

  1. NANOCOMPOSITE COATINGS WITH ENHANCED HARDNESS

    Institute of Scientific and Technical Information of China (English)

    J. Musil

    2005-01-01

    The article reviews the present state of the art in the magnetron sputtering of hart and superhard nanocomposite coatings. It is shown that there are (1) two groups of hard and superhard nanocomposites: (i) nc-MN/hard phase and (ii) nc-MN/soft phase, (2) three possible origins of the enhanced hardness: (i) dislocation-dominated plastic deformation, (ii) cohesive forces between atoms and (iii) nanostructure of materials, and (3) huge differences in the microstructure of single- and two-phase films. A main attention is devoted to the formation of nanocrystalline and/or X-ray amorphous films. Such films are created in a vicinity of transitions between (i)crystalline and amorphous phases, (ii) two crystalline phases of different chemical composition or (iii) two different preferred orientations of grains of the sane material from which the coating is composed. The existence of the last transition makes it possible to explain the enhanced hardness in single-phase films. The thermal stability and oxidation resistance of hard nanocomposite films is also shortly discussed.

  2. Production Performance of the ATLAS Semiconductor Tracker Readout System

    CERN Document Server

    Mitsou, V A

    2006-01-01

    The ATLAS Semiconductor Tracker (SCT) together with the pixel and the transition radiation detectors will form the tracking system of the ATLAS experiment at LHC. It will consist of 20000 single-sided silicon microstrip sensors assembled back-to-back into modules mounted on four concentric barrels and two end-cap detectors formed by nine disks each. The SCT module production and testing has finished while the macro-assembly is well under way. After an overview of the layout and the operating environment of the SCT, a description of the readout electronics design and operation requirements will be given. The quality control procedure and the DAQ software for assuring the electrical functionality of hybrids and modules will be discussed. The focus will be on the electrical performance results obtained during the assembly and testing of the end-cap SCT modules.

  3. Functional Nanoscale Electronic Devices Assembled Using Silicon Nanowire Building Blocks

    Science.gov (United States)

    Cui, Yi; Lieber, Charles M.

    2001-02-01

    Because semiconductor nanowires can transport electrons and holes, they could function as building blocks for nanoscale electronics assembled without the need for complex and costly fabrication facilities. Boron- and phosphorous-doped silicon nanowires were used as building blocks to assemble three types of semiconductor nanodevices. Passive diode structures consisting of crossed p- and n-type nanowires exhibit rectifying transport similar to planar p-n junctions. Active bipolar transistors, consisting of heavily and lightly n-doped nanowires crossing a common p-type wire base, exhibit common base and emitter current gains as large as 0.94 and 16, respectively. In addition, p- and n-type nanowires have been used to assemble complementary inverter-like structures. The facile assembly of key electronic device elements from well-defined nanoscale building blocks may represent a step toward a ``bottom-up'' paradigm for electronics manufacturing.

  4. Investigation on Spin Dependent Transport Properties of Core-Shell Structural Fe3O4/ZnS Nanocomposites for Spintronic Application

    Science.gov (United States)

    Liu, Er; Yuan, Honglei; Kou, Zhaoxia; Wu, Xiumei; Xu, Qingyu; Zhai, Ya; Sui, Yunxia; You, Biao; Du, Jun; Zhai, Hongru

    2015-01-01

    The core-shell structural Fe3O4/ZnS nanocomposites with controllable shell thickness were well-fabricated via seed-mediate growth method. Structural and morphological characterizations reveal the direct deposition of crystalline II-VI compound semiconductor ZnS shell layer on Fe3O4 particles. Spin dependent electrical transport is studied on Fe3O4/ZnS nanocomposites with different shell thickness, and a large magnetoresistance (MR) ratio is observed under the magnetic field of 1.0 T at room temperature and 100 K for the compacted sample by Fe3O4/ZnS nanocomposites, which is 50% larger than that of sample with pure Fe3O4 particles, indicating that the enhanced MR is contributed from the spin injection between Fe3O4 and ZnS layer. PMID:26053888

  5. Semiconductor device PN junction fabrication using optical processing of amorphous semiconductor material

    Energy Technology Data Exchange (ETDEWEB)

    Sopori, Bhushan; Rangappan, Anikara

    2014-11-25

    Systems and methods for semiconductor device PN junction fabrication are provided. In one embodiment, a method for fabricating an electrical device having a P-N junction comprises: depositing a layer of amorphous semiconductor material onto a crystalline semiconductor base, wherein the crystalline semiconductor base comprises a crystalline phase of a same semiconductor as the amorphous layer; and growing the layer of amorphous semiconductor material into a layer of crystalline semiconductor material that is epitaxially matched to the lattice structure of the crystalline semiconductor base by applying an optical energy that penetrates at least the amorphous semiconductor material.

  6. Nanocrystal-polymer nanocomposite electrochromic device

    Science.gov (United States)

    Milliron, Delia; Runnerstrom, Evan; Helms, Brett; Llordes, Anna; Buonsanti, Raffaella; Garcia, Guillermo

    2015-12-08

    Described is an electrochromic nanocomposite film comprising a solid matrix of an oxide based material, the solid matrix comprising a plurality of transparent conducting oxide (TCO) nanostructures dispersed in the solid matrix and a lithium salt dispersed in the solid matrix. Also described is a near infrared nanostructured electrochromic device having a functional layer comprising the electrochromic nanocomposite film.

  7. Organic/inorganic nanocomposite polymer electrolyte

    Institute of Scientific and Technical Information of China (English)

    Li Qi; Shao Jun Dong

    2007-01-01

    The organic/inorganic nanocomposites polymer electrolytes were designed and synthesized. The organic/inorganic nanocom posites membrane materials and their lithium salt complexes have been found thermally stable below 200 ℃. The conductivity of the organic/inorganic nanocomposites polymer electrolytes prepared at room temperature was at magnitude range of 10-6 S/cm.

  8. "Green" composites and nanocomposites from soybean oil

    Science.gov (United States)

    In this study, we report preparation of epoxidized soybean oil (ESO) based "green" composites and nanocomposites. The high strength and stiffness composites and nanocomposites are formed through flax fiber and organoclay reinforcement. The epoxy resin, 1,1,1-tris(p-hydroxyphenyl)ethane triglycidyl...

  9. Superhard nano-multilayers and nanocomposite coatings

    Institute of Scientific and Technical Information of China (English)

    BAI Xiaoming; ZHENG Weitao; AN Tao

    2005-01-01

    This paper reviews the recent development of nano-multilayers and nanocomposite coatings. The hardening mechanisms and design of hard coating are discussed in details. Recent research on Ti/TiN and nitride/nitride multilayer, Ti-Si-N and Ti-Al-Si-N nanocomposite coatings is described, and the perspectives of the related research are proposed.

  10. General Assembly

    CERN Multimedia

    Staff Association

    2016-01-01

    5th April, 2016 – Ordinary General Assembly of the Staff Association! In the first semester of each year, the Staff Association (SA) invites its members to attend and participate in the Ordinary General Assembly (OGA). This year the OGA will be held on Tuesday, April 5th 2016 from 11:00 to 12:00 in BE Auditorium, Meyrin (6-2-024). During the Ordinary General Assembly, the activity and financial reports of the SA are presented and submitted for approval to the members. This is the occasion to get a global view on the activities of the SA, its financial management, and an opportunity to express one’s opinion, including taking part in the votes. Other points are listed on the agenda, as proposed by the Staff Council. Who can vote? Only “ordinary” members (MPE) of the SA can vote. Associated members (MPA) of the SA and/or affiliated pensioners have a right to vote on those topics that are of direct interest to them. Who can give his/her opinion? The Ordinary General Asse...

  11. Design of nanocomposite polymer coatings for MEMS applications

    Science.gov (United States)

    Julthongpiput, Duangrut

    The recent evolution in microelectronics of combining electrical and mechanical functions has brought about the exciting field of microelectromechanical system (MEMS). As the dimensions of the components shrink, adhesion, stiction, friction, and wear become a significant technological barrier for the successful development of durable microdevices. In this thesis, we investigate wear-resistant, nanocomposite, molecular coatings from advanced polymers with controlled nanomechanical and nanotribological properties from the prospective of long-term applications for MEMS. We discuss fundamentals governing the mechanical and tribological properties on a micro scale associated with the morphology and microstructure of these molecular coatings. In order to fabricate wear-resistant and superelastic molecular coatings, several types of the molecular designs are proposed and tested in this work. All designs are based on chemical attachment of the polymer layers onto a functionalized silicon surface. We focus on developing two different kinds of molecular coatings: reinforced elastomeric layers from grafted block-copolymers and polymer brush layers grown by the "grafted to" technique. A more complicated design included bilayered nanocomposite coatings consisting of a hard polymer layer placed on the top of an elastomeric layer to regulate surface adhesion and to increase surface stiffness of nanocomposite bilayers. Another design incorporates a paraffinic oil component to assure the presence of highly mobile molecules inside of the elastomeric phase. This oily fraction can be a source of an instant supply of mobile lubricant to a deformed contact area, thus providing potential self-lubrication and self-healing mechanisms for surface areas affected by excessive deformation. We observed that the interfacial assemblies, as presented in this paper, exhibited very low friction coefficient, low stiction, and better wear stability as compared to other, non-structured, non

  12. Activation of Al–Cu–Fe quasicrystalline surface: fabrication of a fine nanocomposite layer with high catalytic performance

    Directory of Open Access Journals (Sweden)

    Satoshi Kameoka

    2014-01-01

    Full Text Available A fine layered nanocomposite with a total thickness of about 200 nm was formed on the surface of an Al63Cu25Fe12 quasicrystal (QC. The nanocomposite was found to exhibit high catalytic performance for steam reforming of methanol. The nanocomposite was formed by a self-assembly process, by leaching the Al–Cu–Fe QC using a 5 wt% Na2CO3 aqueous solution followed by calcination in air at 873 K. The quasiperiodic nature of the QC played an important role in the formation of such a structure. Its high catalytic activity originated from the presence of highly dispersed copper and iron species, which also suppressed the sintering of nanoparticles.

  13. Nanocomposite organomineral hybrid materials. Part I

    Directory of Open Access Journals (Sweden)

    KUDRYAVTSEV Pavel Gennadievich

    2016-02-01

    Full Text Available The paper addresses the issues of alkoxide method of sol-gel synthesis and non-hydrolytic method of sol-gel synthesis and colloidal method of sol-gel synthesis. The authors also consider an alternative approach based on the use of soluble silicates as precursors in the sol-gel technology, of nanocomposites. It was shown that nanocomposites can be produced through aerogels. The paper also analyzes the mixing technologies of nanocomposites preparation. It has been demonstrated the possibility to change the types of nano-phase which is used for obtaining nanocomposites in different approaches. Various models of packaging spherical, fibrous and layered nanoparticles, introduced into the structure of the nanocomposite, in the preparation thereof were examined.

  14. Nanocomposite organomineral hybrid materials. Part 3

    Directory of Open Access Journals (Sweden)

    KUDRYAVTSEV Pavel Gennadievich

    2016-06-01

    Full Text Available The paper addresses the issues of alkoxide method of sol-gel synthesis and non-hydrolytic method of sol-gel synthesis and colloidal method of sol-gel synthesis. The authors also consider an alternative approach based on the use of soluble silicates as precursors in the sol-gel technology, of nanocomposites. It was shown that nanocomposites can be produced through aerogels. The paper also analyzes the mixing technologies of nanocomposites preparation. It has been demonstrated the possibility to change the types of nano-phase which is used for obtaining nanocomposites in different approaches. Various models of packaging spherical, fibrous and layered nanoparticles, introduced into the structure of the nanocomposite, in the preparation thereof were examined.

  15. Nanocomposite organomineral hybrid materials. Part 2

    Directory of Open Access Journals (Sweden)

    KUDRYAVTSEV Pavel Gennadievich

    2016-04-01

    Full Text Available The paper addresses the issues of alkoxide method of sol-gel synthesis and non-hydrolytic method of sol-gel synthesis and colloidal method of sol-gel synthesis. The authors also consider an alternative approach based on the use of soluble silicates as precursors in the sol-gel technology, of nanocomposites. It was shown that nanocomposites can be produced through aerogels. The paper also analyzes the mixing technologies of nanocomposites preparation. It has been demonstrated the possibility to change the types of nano-phase which is used for obtaining nanocomposites in different approaches. Various models of packaging spherical, fibrous and layered nanoparticles, introduced into the structure of the nanocomposite, in the preparation thereof were examined.

  16. Description of Extrudate Swell for Polymer Nanocomposites

    Directory of Open Access Journals (Sweden)

    Kejian Wang

    2010-01-01

    Full Text Available Extrudate swell is often observed to be weakened in nanocomposites compared to the pure polymer matrix. A theory quantifying this would be significant either for optimum processing or for understanding their viscoelasticity. A unified extrudate swell correlation with material properties and capillary parameters was suggested for polymer melt and their nanocomposites when considering the reservoir entry effect. More importantly, it was the first to find that the composite swell ratio can be the matrix swell ratio multiplied by the concentration shift factor, which is similar to the dynamic moduli expression for composites. The factor is a function of the shear field (stress or shear rate, filler content, filler internal structure and the surface state as well as the matrix properties. Several sets of swell data for nanocomposites were chosen from publications to test the new theories. The proposed quantitative model displayed good fit for the five kinds of nanocomposites, which verified the rationality of the swell theory for nanocomposites.

  17. Fabrication and properties of multiferroic nanocomposite films

    KAUST Repository

    Al-Nassar, Mohammed Y.

    2015-01-01

    A new type of multiferroic polymer nanocomposite is presented, which exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature. The multiferroic nanocomposite consists of a ferroelectric copolymer poly(vinylindene fluoride-trifluoroethylene) [P(VDF-TrFE)] and high aspect ratio ferromagnetic nickel (Ni) nanowires (NWs), which were grown inside anodic aluminum oxide membranes. The fabrication of nanocomposite films with Ni NWs embedded in P(VDF-TrFE) has been successfully carried out via a simple low-temperature spin-coating technique. Structural, ferromagnetic, and ferroelectric properties of the developed nanocomposite have been investigated. The remanent and saturation polarization as well as the coercive field of the ferroelectric phase are slightly affected by the incorporation of the NWs as well as the thickness of the films. While the former two decrease, the last increases by adding the NWs or increasing the thickness. The ferromagnetic properties of the nanocomposite films are found to be isotropic.

  18. Advances in rubber/halloysite nanotubes nanocomposites.

    Science.gov (United States)

    Jia, Zhixin; Guo, Baochun; Jia, Demin

    2014-02-01

    The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method. A series of rubber/HNTs nanocomposites containing several rubbers (SBR, NR, xSBR, NBR, PU) and different modifiers (ENR, RH, Si69, SA, MAA, ILs) have been investigated. The results showed that all the rubber/HNTs nanocomposites achieved strong interfacial interaction via interfacial covalent bonds, hydrogen bonds or multiple interactions, realized significantly improved dispersion of HNTs at nanoscale and exhibited excellent mechanical performances and other properties. PMID:24749454

  19. Metal-Insulator-Semiconductor Photodetectors

    Directory of Open Access Journals (Sweden)

    Chu-Hsuan Lin

    2010-09-01

    Full Text Available The major radiation of the Sun can be roughly divided into three regions: ultraviolet, visible, and infrared light. Detection in these three regions is important to human beings. The metal-insulator-semiconductor photodetector, with a simpler process than the pn-junction photodetector and a lower dark current than the MSM photodetector, has been developed for light detection in these three regions. Ideal UV photodetectors with high UV-to-visible rejection ratio could be demonstrated with III-V metal-insulator-semiconductor UV photodetectors. The visible-light detection and near-infrared optical communications have been implemented with Si and Ge metal-insulator-semiconductor photodetectors. For mid- and long-wavelength infrared detection, metal-insulator-semiconductor SiGe/Si quantum dot infrared photodetectors have been developed, and the detection spectrum covers atmospheric transmission windows.

  20. Signal processing for semiconductor detectors

    International Nuclear Information System (INIS)

    A balanced perspective is provided on the processing of signals produced by semiconductor detectors. The general problems of pulse shaping to optimize resolution with constraints imposed by noise, counting rate and rise time fluctuations are discussed

  1. An ab initio design of cluster-assembled silicon nanotubes

    OpenAIRE

    Guo, Lingju; Zheng, Xiaohong; Liu, Chunsheng; Zeng, Zhi

    2010-01-01

    Density functional calculations were performed to systematically study a series of finite and infinite cluster-assembled silicon nanotubes (SiNTs). One-dimensional SiNTs can be prepared by proper assembly of hydrogenated cage-like silicon clusters to form semiconductors with a large band gap, and their electronic properties can be accurately tuned by transition metal doping in the center of the tubes. Specifically, doping with Fe made the SiNTs metallic and magnetic materials. More interestin...

  2. Location deterministic biosensing from quantum-dot-nanowire assemblies

    OpenAIRE

    Liu, Chao; Kim, Kwanoh; Fan, D. L.

    2014-01-01

    Semiconductor quantum dots (QDs) with high fluorescent brightness, stability, and tunable sizes, have received considerable interest for imaging, sensing, and delivery of biomolecules. In this research, we demonstrate location deterministic biochemical detection from arrays of QD-nanowire hybrid assemblies. QDs with diameters less than 10 nm are manipulated and precisely positioned on the tips of the assembled Gold (Au) nanowires. The manipulation mechanisms are quantitatively ...

  3. A simple two-step method to fabricate highly transparent ITO/polymer nanocomposite films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Haitao [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Zeng, Xiaofei, E-mail: zengxf@mail.buct.edu.cn [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Kong, Xiangrong [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Bian, Shuguang [The High Technology Research and Development Center, The Ministry of Science and Technology, Beijing 100044 (China); Chen, Jianfeng [Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer A simple two-step method without further surface modification step was employed. Black-Right-Pointing-Pointer ITO nanoparticles were easily to be uniformly dispersed in polymer matrix. Black-Right-Pointing-Pointer ITO/polymer nanocomposite film had high transparency and UV/IR blocking properties. - Abstract: Transparent functional indium tin oxide (ITO)/polymer nanocomposite films were fabricated via a simple approach with two steps. Firstly, the functional monodisperse ITO nanoparticles were synthesized via a facile nonaqueous solvothermal method using bifunctional chemical agent (N-methyl-pyrrolidone, NMP) as the reaction solvent and surface modifier. Secondly, the ITO/acrylics polyurethane (PUA) nanocomposite films were fabricated by a simple sol-solution mixing method without any further surface modification step as often employed traditionally. Flower-like ITO nanoclusters with about 45 nm in diameter were mono-dispersed in ethyl acetate and each nanocluster was assembled by nearly spherical nanoparticles with primary size of 7-9 nm in diameter. The ITO nanoclusters exhibited an excellent dispersibility in polymer matrix of PUA, remaining their original size without any further agglomeration. When the loading content of ITO nanoclusters reached to 5 wt%, the transparent functional nanocomposite film featured a high transparency more than 85% in the visible light region (at 550 nm), meanwhile cutting off near-infrared radiation about 50% at 1500 nm and blocking UV ray about 45% at 350 nm. It could be potential for transparent functional coating materials applications.

  4. A Convenient Ultraviolet Irradiation Technique for Synthesis of Antibacterial Ag-Pal Nanocomposite

    Science.gov (United States)

    Han, Shuai; Zhang, He; Kang, Lianwei; Li, Xiaoliang; Zhang, Chong; Dong, Yongjie; Qin, Shenjun

    2016-09-01

    In the present work, palygorskite (Pal) was initially subjected to an ion-exchange reaction with silver ions (Pal-Ag+). Subsequently, Ag-Pal nanocomposites were assembled by a convenient ultraviolet irradiation technique, using carbon dots (CDs) derived from wool fiber as the reducing agent. The obtained nanocomposites were characterized by powder X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy. The XRD patterns and UV-vis absorption spectra confirmed the formation of the Ag nanoparticles (NPs). Meanwhile, the TEM images showed that the Ag NPs, which exhibited sizes in the range of 3-7 nm, were located on the surface of the Pal nanofiber structures. Furthermore, the antibacterial activity of the nanocomposites was evaluated against Gram-positive ( Staphylococcus aureus) and Gram-negative ( Escherichia coli) bacteria by applying the disc diffusion method and minimum inhibitory concentration test. Owing to their good antibacterial properties, the Ag-Pal nanocomposites are considered to be a promising bactericide with great potential applications.

  5. Electrochemical detection of nitrite on poly(pyronin Y)/graphene nanocomposites modified ITO substrate

    Science.gov (United States)

    Şinoforoğlu, Mehmet; Dağcı, Kader; Alanyalıoğlu, Murat; Meral, Kadem

    2016-06-01

    The present study reports on an easy preparation of poly(pyronin Y)/graphene (poly(PyY)/graphene) nanocomposites thin films on indium tin oxide coated glass substrates (ITO). The thin films of poly(PyY)/graphene nanocomposites are prepared by a novel method consisting of three steps; (i) preparation of graphene oxide (GO) thin films on ITO by spin-coating method, (ii) self-assembly of PyY molecules from aqueous solution onto the GO thin film, (iii) surface-confined electropolymerization (SCEP) of the adsorbed PyY molecules on the GO thin film. The as-prepared poly(PyY)/graphene nanocomposites thin films are characterized by using electroanalytical and spectroscopic techniques. Afterwards, the graphene-based polymeric dye thin film on ITO is used as an electrode in an electrochemical cell. Its performance is tested for electrochemical detection of nitrite. Under optimized conditions, the electrocatalytical effect of the nanocomposites thin film through electrochemical oxidation of nitrite is better than that of GO coated ITO.

  6. A simple two-step method to fabricate highly transparent ITO/polymer nanocomposite films

    International Nuclear Information System (INIS)

    Highlights: ► A simple two-step method without further surface modification step was employed. ► ITO nanoparticles were easily to be uniformly dispersed in polymer matrix. ► ITO/polymer nanocomposite film had high transparency and UV/IR blocking properties. - Abstract: Transparent functional indium tin oxide (ITO)/polymer nanocomposite films were fabricated via a simple approach with two steps. Firstly, the functional monodisperse ITO nanoparticles were synthesized via a facile nonaqueous solvothermal method using bifunctional chemical agent (N-methyl-pyrrolidone, NMP) as the reaction solvent and surface modifier. Secondly, the ITO/acrylics polyurethane (PUA) nanocomposite films were fabricated by a simple sol-solution mixing method without any further surface modification step as often employed traditionally. Flower-like ITO nanoclusters with about 45 nm in diameter were mono-dispersed in ethyl acetate and each nanocluster was assembled by nearly spherical nanoparticles with primary size of 7–9 nm in diameter. The ITO nanoclusters exhibited an excellent dispersibility in polymer matrix of PUA, remaining their original size without any further agglomeration. When the loading content of ITO nanoclusters reached to 5 wt%, the transparent functional nanocomposite film featured a high transparency more than 85% in the visible light region (at 550 nm), meanwhile cutting off near-infrared radiation about 50% at 1500 nm and blocking UV ray about 45% at 350 nm. It could be potential for transparent functional coating materials applications.

  7. The Impact of Fullerenes on the Ordering of Polyacrylonitrile in Nanocomposites

    Science.gov (United States)

    Imel, Adam; Dadmun, Mark

    2013-03-01

    The presence of nanoparticles can impact the crystallization and ordering of polymer chains in a nanocomposite. We have found that certain fabrication conditions of polyacrylonitrile (PAN) and fullerenes, as well as PAN and SWNTs, produce a SAXS peak. This SAXS peak is similar to a microphase separation peak and indicates a self-assembly of the nanocomposite on a length scale of ~ 150 Å. In order to identify the origin of this peak, we have completed dynamic light scattering, viscosity, small angle x-ray scattering and wide-angle x-ray scattering experiments to characterize the dispersion of C60 in solution and in the final solid nanocomposite. These results support a completely miscible solution. The interpretation of the SAXS & WAXS results suggest that the addition of C60 directs the crystallization of PAN in the final nanocomposite by dramatically decreasing the amount of crystallinity while also affecting the packing structure and limiting the size of the PAN crystals. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering

  8. A Convenient Ultraviolet Irradiation Technique for Synthesis of Antibacterial Ag-Pal Nanocomposite.

    Science.gov (United States)

    Han, Shuai; Zhang, He; Kang, Lianwei; Li, Xiaoliang; Zhang, Chong; Dong, Yongjie; Qin, Shenjun

    2016-12-01

    In the present work, palygorskite (Pal) was initially subjected to an ion-exchange reaction with silver ions (Pal-Ag(+)). Subsequently, Ag-Pal nanocomposites were assembled by a convenient ultraviolet irradiation technique, using carbon dots (CDs) derived from wool fiber as the reducing agent. The obtained nanocomposites were characterized by powder X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy. The XRD patterns and UV-vis absorption spectra confirmed the formation of the Ag nanoparticles (NPs). Meanwhile, the TEM images showed that the Ag NPs, which exhibited sizes in the range of 3-7 nm, were located on the surface of the Pal nanofiber structures. Furthermore, the antibacterial activity of the nanocomposites was evaluated against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria by applying the disc diffusion method and minimum inhibitory concentration test. Owing to their good antibacterial properties, the Ag-Pal nanocomposites are considered to be a promising bactericide with great potential applications. PMID:27677302

  9. A novel method for fabricating hybrid biobased nanocomposites film with stable fluorescence containing CdTe quantum dots and montmorillonite-chitosan nanosheets.

    Science.gov (United States)

    Guo, Yawen; Ge, Xuesong; Guan, Jing; Wu, Lin; Zhao, Fuhua; Li, Hui; Mu, Xindong; Jiang, Yijun; Chen, Aibing

    2016-07-10

    A method was presented for fabricating the fluorescent nanocomposites containing CdTe quantum dots (QDs) and montmorillonite (MMT)-chitosan (CS). MMT-CS/CdTe QDs nanocomposites were prepared via a simple, versatile and robust approach combination of covalent and electrostatic assembly methods (Scheme 1). The negatively charged MMT was initially modified with positively charged CS through electrostatic assembly, followed by incorporation of CdTe-QDs into the MMT-CS nanosheets by covalent connections between the amino groups of CS and the carboxylic acid groups of thioglycollic acid (TGA). The X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and the FTIR were used to prove the QDs have intercalated into the MMT-CS matrix. The fluorescence emission spectra showed that the MMT-CS/CdTe QDs nanocomposites had the best fluorescence intensity compared with the bare CdTe QDs and CS-QDs. PMID:27106146

  10. Simulation in Semiconductor Manufacturing Facilities

    OpenAIRE

    Arisha, Amr; Young, Paul

    2005-01-01

    Semiconductor manufacturing is one of the most complex industries in terms of technology and manufacturing procedure. The life cycle of a semiconductor facility (FAB) has many phases, in their life cycle including capacity planning, new products introduction, variation of products/technologies, and decline phase. The complexity of the manufacturing and the external forces from markets and technology growth make predicting the effects of changes in the manufacturing system problematic. Simulat...

  11. Dissipative chaos in semiconductor superlattices

    Directory of Open Access Journals (Sweden)

    F. Moghadam

    2008-03-01

    Full Text Available In this paper the motion of electron in a miniband of a semiconductor superlattice (SSL under the influence of external electric and magnetic fields is investigated. The electric field is applied in a direction perpendicular to the layers of the semiconductor superlattice, and the magnetic field is applied in different direction Numerical calculations show conditions led to the possibility of chaotic behaviors.

  12. Statistical Methods for Semiconductor Manufacturing

    OpenAIRE

    Susto, Gian Antonio

    2013-01-01

    In this thesis techniques for non-parametric modeling, machine learning, filtering and prediction and run-to-run control for semiconductor manufacturing are described. In particular, algorithms have been developed for two major applications area: - Virtual Metrology (VM) systems; - Predictive Maintenance (PdM) systems. Both technologies have proliferated in the past recent years in the semiconductor industries, called fabs, in order to increment productivity and decrease costs. ...

  13. Quantum transport in semiconductor nanowires

    OpenAIRE

    Van Dam, J.

    2006-01-01

    This thesis describes a series of experiments aimed at understanding the low-temperature electrical transport properties of semiconductor nanowires. The semiconductor nanowires (1-100 nm in diameter) are grown from nanoscale gold particles via a chemical process called vapor-liquid-solid (VLS) growth. The huge versatility of this material system (e.g. in size and materials) results in a wide range of potential applications in (opto-)electronics. During the last few years many important proofs...

  14. Medical applications of semiconductor lasers

    Science.gov (United States)

    Mancha, Sylvia D.; Keipert, Andreas; Prairie, Michael W.

    1994-06-01

    The High Power Semiconductor Laser Technology (HPSLT) program is currently developing, in-house, a belt pack medical laser. This compact semiconductor laser device provides the field paramedic or physician a unique portable laser capability. The pack consists of a completely self-contained laser system that fits inside a belt pack. Several other medical applications being investigated by the HPSLT program include urological applications, photodynamic therapy, and ophthalmic applications.

  15. Semiconductor crystal high resolution imager

    Science.gov (United States)

    Levin, Craig S. (Inventor); Matteson, James (Inventor)

    2011-01-01

    A radiation imaging device (10). The radiation image device (10) comprises a subject radiation station (12) producing photon emissions (14), and at least one semiconductor crystal detector (16) arranged in an edge-on orientation with respect to the emitted photons (14) to directly receive the emitted photons (14) and produce a signal. The semiconductor crystal detector (16) comprises at least one anode and at least one cathode that produces the signal in response to the emitted photons (14).

  16. A semiconductor laser excitation circuit

    Energy Technology Data Exchange (ETDEWEB)

    Kaadzunari, O.; Masaty, K.

    1984-03-27

    A semiconductor laser excitation circuit is patented that is designed for operation in a pulsed mode with a high pulse repetition frequency. This circuit includes, in addition to a semiconductor laser, a high speed photodetector, a reference voltage source, a comparator, and a pulse oscillator and modulator. If the circuit is built using standard silicon integrated circuits, its speed amounts to several hundred megahertz, if it is constructed using gallium arsenide integrated circuits, its speed is several gigahertz.

  17. Optical Orientation in Ferromagnet/Semiconductor Hybrids

    OpenAIRE

    Korenev, V. L.

    2008-01-01

    The physics of optical pumping of semiconductor electrons in the ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of the ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of the semiconductor. Spin-spin interactions near the interface ferromagnet/semiconductor play crucial role in the optical readout and the manipulation of ferromagnetism.

  18. Reduced graphene oxide-TiO2 nanocomposite as a promising visible-light-active photocatalyst for the conversion of carbon dioxide

    OpenAIRE

    Tan, Lling-Lling; Ong, Wee-Jun; Chai, Siang-Piao; Mohamed, Abdul Rahman

    2013-01-01

    Photocatalytic reduction of carbon dioxide (CO2) into hydrocarbon fuels such as methane is an attractive strategy for simultaneously harvesting solar energy and capturing this major greenhouse gas. Incessant research interest has been devoted to preparing graphene-based semiconductor nanocomposites as photocatalysts for a variety of applications. In this work, reduced graphene oxide (rGO)-TiO2 hybrid nanocrystals were fabricated through a novel and simple solvothermal synthetic route. Anatase...

  19. The ATLAS semiconductor tracker

    CERN Document Server

    Mikuz, Marko

    2003-01-01

    The ATLAS Semiconductor Tracker (SCT) is presented. About 16000 silicon micro-strip sensors with a total active surface of over 60 m **2 and with 6.3 million read-out channels are built into 4088 modules arranged into four barrel layers and nine disks covering each of the forward regions up to an eta of 2.5. Challenges are imposed by the hostile radiation environment with particle fluences up to 2 multiplied by 10**1**4 cm**-**2 1 MeV neutron NIEL equivalent and 100 kGy TID, the 25 ns LHC bunch crossing time and the need for a hermetic, lightweight tracker. The solution adopted is carefully designed strip detectors operated at -7 degree C, biased up to 500 V and read out by binary radhard fast BiCMOS electronics. A zero-CTE carbon fibre structure provides mechanical support. 30 kW of power are supplied on aluminiutn/Kapton tapes and cooled by C//3F//8 evaporative cooling. Data and commands are transferred by optical links. Prototypes of detector modules have been built, irradiated to the maximum expected flue...

  20. A semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Naoko, O.; Khiroiti, S.

    1984-05-20

    An improved method is patented for increasing the service life of semiconductor lasers which does not hinder their characteristics, by applying a protective film to the end planes of the optical resonator of the laser. It is recommended that a mixture of an A1203 dielectric and an inert element such as argon be used for a GaAs, GaA1As laser as the protective film. The radii of gallium and arsenic atoms are equal to 1.24 and 1.25 angstroms, respectively. The radii of A1, O and Si atoms which make up the protective film are equal to 1.43, .61 and 1.17 angstroms, respectively. The radius of the argon atoms in the protective film, which is equal to 1.91 angstroms) is high compared to the atoms noted above. As a result, the movement of the gallium and arsenic atoms, which causes a drop in later characteristics during operation, is made more difficult.

  1. Structural Investigation of Biological and Semiconductor Nanostructures with Nonlinear Multicontrast Microscopy

    Science.gov (United States)

    Cisek, Richard

    Physical and functional properties of advanced nano-composite materials and biological structures are determined by self-organized atoms and molecules into nanostructures and in turn by microscopic organization of the nanostructures into assemblies of higher structural complexity. Therefore, microscopes are indispensable tools for structural investigations at various levels of organization. In this work, novel nonlinear optical microscopy methods were developed to non-invasively study structural organization at the nanoscopic and microscopic levels. Atomic organization of semiconductor nanowires, molecular organization of amylose biocrystallites in starch granules, and microscopic organization of several photosynthetic organisms was elucidated. The structure of ZnSe nanowires, key components in many modern nanodevices, was investigated using polarization harmonic generation microscopy. Based on nonlinear optical properties of the different crystal lattices, zinc blende and wurtzite nanowires were differentiated, and the three-dimensional orientation of the zinc blende nanowires could be found. The structure of starch granules, a model biocrystal, important in food as well as health sciences, was also investigated using polarization harmonic microscopy. The study was combined with ab initio calculations using the crystal structures of amylose A and B, revealing that second harmonic signals originate from the hydroxide and hydrogen bonds in the starch granules. Visualization of several photosynthetic organisms including the green algae, Chlamydomonas reinhardtii, two species of cyanobacteria, Leptolyngbya sp. and Anabaena sp., aggregates of light-harvesting pigment-protein complexes as well as chloroplasts from green plants were also explored, revealing that future nonlinear microscopy applications could include structural studies of cell walls, the Chlamydomonas eyespot, and photosynthetic membranes. In this study, several nonlinear optical microscopy modalities

  2. Fabrication and capacitance of Ni{sup 2+}-Fe{sup 3+} LDHs/MnO{sub 2} layered nanocomposite via an exfoliation/reassembling process

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongjuan; Deng Lingjuan; Zhu Gang; Kang Liping [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi' an 710062 (China); School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China); Liu Zonghuai, E-mail: zhliu@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi' an 710062 (China); School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)

    2012-01-25

    Highlights: Black-Right-Pointing-Pointer Ni{sup 2+}-Fe{sup 3+} LDHs/MnO{sub 2} layered nanocomposite has been fabricated via both layer-by-layer self-assembly and flocculated methods. Black-Right-Pointing-Pointer Ni{sup 2+}-Fe{sup 3+} LDHs nanosheets and MnO{sub 2} nanosheets can be deposited onto multilayer film uniformly by electrostatic interaction. Black-Right-Pointing-Pointer Ni{sup 2+}-Fe{sup 3+} LDHs/MnO{sub 2} layered nanocomposite exhibits a relative good capacitive behavior. - Abstract: Ni{sup 2+}-Fe{sup 3+} layered double hydroxides (LDHs)/MnO{sub 2} layered nanocomposite has been fabricated by using both layer-by-layer self-assembly method and flocculated technology, based on electrostatic interaction of positively charged Ni{sup 2+}-Fe{sup 3+} LDHs nanosheets and negatively charged MnO{sub 2} nanosheets. Ultraviolet-visible spectroscopy is used to probe the dynamic growth of the multilayer film, exhibiting progressive enhancement of optical absorption due to the assembly of Ni{sup 2+}-Fe{sup 3+} LDHs nanosheets and MnO{sub 2} nanosheets. The assembled Ni{sup 2+}-Fe{sup 3+} LDHs/MnO{sub 2} nanocomposite has been characterized by XRD, SEM and TEM. The electrochemical property of the synthesized Ni{sup 2+}-Fe{sup 3+} LDHs/MnO{sub 2} layered nanocomposite has been studied using cyclic voltammetry in a mild aqueous electrolyte. The Ni{sup 2+}-Fe{sup 3+} LDHs/MnO{sub 2} nanocomposite exhibits a relative good capacitive behavior in a neutral electrolyte system, and its initial capacitance value is 104 F g{sup -1}.

  3. Confinement-Enhanced Electron Transport across a Metal-Semiconductor Interface

    OpenAIRE

    Altfeder, I. B.; Golovchenko, Jene Andrew; Narayanamurti, Venkatesh

    2001-01-01

    We present a combined scanning tunneling microscopy and ballistic electron emission microscopy study of electron transport across an epitaxial Pb/Si(111) interface. Experiments with a self-assembled Pb nanoscale wedge reveal the phenomenon of confinement-enhanced interfacial transport: a proportional increase of the electron injection rate into the semiconductor with the frequency of electron oscillations in the Pb quantum well.

  4. Assembling consumption

    DEFF Research Database (Denmark)

    Assembling Consumption marks a definitive step in the institutionalisation of qualitative business research. By gathering leading scholars and educators who study markets, marketing and consumption through the lenses of philosophy, sociology and anthropology, this book clarifies and applies...... the investigative tools offered by assemblage theory, actor-network theory and non-representational theory. Clear theoretical explanation and methodological innovation, alongside empirical applications of these emerging frameworks will offer readers new and refreshing perspectives on consumer culture and market...... societies. This is an essential reading for both seasoned scholars and advanced students of markets, economies and social forms of consumption....

  5. Heater assembly

    International Nuclear Information System (INIS)

    An electrical resistance heater, installed in the H1 borehole, is used to thermally perturb the rock mass through a controlled heating and cooling cycle. Heater power levels are controlled by a Variac power transformer and are measured by wattmeters. Temperatures are measured by thermocouples on the borehole wall and on the heater assembly. Power and temperature values are recorded by the DAS described in Chapter 12. The heater assembly consists of a 3.55-m (11.6-ft) long by 20.3-cm (8-in.) O.D., Type 304 stainless steel pipe, containing a tubular hairpin heating element. The element has a heated length of 3 m (9.84 ft). The power rating of the element is 10 kW; however, we plan to operate the unit at a maximum power of only 3 kW. The heater is positioned with its midpoint directly below the axis of the P2 borehole, as shown in the borehole configuration diagram. This heater midpoint position corresponds to a distance of approximately 8.5 m (27.9 ft) from the H1 borehole collar. A schematic of the heater assembly in the borehole is shown. The distance from the borehole collar to the closest point on the assembly (the front end) is 6.5 m (21.3 ft). A high-temperature inflatable packer, used to seal the borehole for moisture collection, is positioned 50 cm (19.7 in.) ahead of the heater front end. The heater is supported and centralized within the borehole by two skids, fabricated from 25-mm (1-in.) O.D. stainless steel pipe. Thermocouples are installed at a number of locations in the H1 borehole. Four thermocouples that are attached to the heater skin monitor temperatures on the outer surface of the can, while three thermocouples that are held in place by rock sections monitor borehole wall temperatures beneath the heater. Temperatures are also monitored at the heater terminal and on the packer hardware

  6. Effect of cationic surfactants on characteristics and colorimetric behavior of polydiacetylene/silica nanocomposite as time-temperature indicator

    Science.gov (United States)

    Nopwinyuwong, Atchareeya; Kitaoka, Takuya; Boonsupthip, Waraporn; Pechyen, Chiravoot; Suppakul, Panuwat

    2014-09-01

    Polydiacetylene (PDA)/silica nanocomposites were synthesized by self-assembly method using polymerizable amphiphilic diacetylene monomers, 10,12-pentacosadiynoic acid (PCDA). Addition of cationic surfactants (PDADMAC and CTAB) to PDA/SiO2 nanocomposites induced higher intermolecular force which affected their size, shape and color transition. Pure PDA, PDA/SiO2, PDA/SiO2/PDADMAC and PDA/SiO2/CTAB were investigated by particle size analysis, TEM, SEM, UV-vis spectroscopy and FT-IR. It was found that the PDA/SiO2 nanocomposites exhibited slightly larger particle sizes than those of other samples. The PDA/SiO2 nanocomposites with a core-shell structure were almost regarded as spherical-shaped particles. Cationic surfactants, especially CTAB, presumably affected the particle size and shape of PDA/SiO2 nanocomposites due to the disruption of hydrogen bonding between PDA head group and ammonium group. The colorimetric response of both PDA/SiO2/surfactant and surfactant-free PDA/SiO2 aqueous solutions directly changed in relation to time and temperature; thus they were expected to be applied as a new polymer-based time-temperature indicator (TTI).

  7. Optical systems fabricated by printing-based assembly

    Science.gov (United States)

    Rogers, John; Nuzzo, Ralph; Meitl, Matthew; Menard, Etienne; Baca, Alfred J.; Motala, Michael; Ahn, Jong-Hyun; Park, Sang-II; Yu; Chang-Jae; Ko, Heung-Cho; Stoykovich; Mark; Yoon, Jongseung

    2011-07-05

    Provided are optical devices and systems fabricated, at least in part, via printing-based assembly and integration of device components. In specific embodiments the present invention provides light emitting systems, light collecting systems, light sensing systems and photovoltaic systems comprising printable semiconductor elements, including large area, high performance macroelectronic devices. Optical systems of the present invention comprise semiconductor elements assembled, organized and/or integrated with other device components via printing techniques that exhibit performance characteristics and functionality comparable to single crystalline semiconductor based devices fabricated using conventional high temperature processing methods. Optical systems of the present invention have device geometries and configurations, such as form factors, component densities, and component positions, accessed by printing that provide a range of useful device functionalities. Optical systems of the present invention include devices and device arrays exhibiting a range of useful physical and mechanical properties including flexibility, shapeability, conformability and stretchablity.

  8. Measuring the specific contact resistance of contacts to semiconductor nanowires

    Science.gov (United States)

    Mohney, S. E.; Wang, Y.; Cabassi, M. A.; Lew, K. K.; Dey, S.; Redwing, J. M.; Mayer, T. S.

    2005-02-01

    Ohmic contacts to semiconductor nanowires are essential components of many new nanoscale electronic devices. Equations for extracting specific contact resistance (or contact resistivity) from several different test structures have been developed by modeling the metal/semiconductor contact as a transmission line, leading to the development of equations analogous to those used for planar contacts. The advantages and disadvantages of various test structures are discussed. To fabricate test structures using a convenient four-point approach, silicon nanowires have been aligned using field-assisted assembly and contacts fabricated. Finally, specific contact resistances near 5 × 10 -4 Ω cm 2 have been measured for Ti/Au contacts to p-type Si nanowires with diameters of 78 and 104 nm.

  9. Optical Fano resonance of an individual semiconductor nanostructure.

    Science.gov (United States)

    Fan, Pengyu; Yu, Zongfu; Fan, Shanhui; Brongersma, Mark L

    2014-05-01

    Fano resonances with a characteristic asymmetric line shape can be observed in light scattering, transmission and reflection spectra of resonant optical systems. They result from interference between direct and indirect, resonance-assisted pathways. In the nanophotonics field, Fano effects have been observed in a wide variety of systems, including metallic nanoparticle assemblies, metamaterials and photonic crystals. Their unique properties find extensive use in applications, including optical filtering, polarization selectors, sensing, lasers, modulators and nonlinear optics. We report on the observation of a Fano resonance in a single semiconductor nanostructure, opening up opportunities for their use in active photonic devices. We also show that Fano-resonant semiconductor nanostructures afford the intriguing opportunity to simultaneously measure the far-field scattering response and the near-field energy storage by extracting photogenerated charge. Together they can provide a complete experimental characterization of this type of resonance. PMID:24747781

  10. Magnetically anisotropic additive for scalable manufacturing of polymer nanocomposite: iron-coated carbon nanotubes

    Science.gov (United States)

    Yamamoto, Namiko; Manohara, Harish; Platzman, Ellen

    2016-02-01

    Novel nanoparticles additives for polymer nanocomposites were prepared by coating carbon nanotubes (CNTs) with ferromagnetic iron (Fe) layers, so that their micro-structures can be bulk-controlled by external magnetic field application. Application of magnetic fields is a promising, scalable method to deliver bulk amount of nanocomposites while maintaining organized nanoparticle assembly throughout the uncured polymer matrix. In this work, Fe layers (˜18 nm thick) were deposited on CNTs (˜38 nm diameter and ˜50 μm length) to form thin films with high aspect ratio, resulting in a dominance of shape anisotropy and thus high coercivity of ˜50-100 Oe. The Fe-coated CNTs were suspended in water and applied with a weak magnetic field of ˜75 G, and yet preliminary magnetic assembly was confirmed. Our results demonstrate that the fabricated Fe-coated CNTs are magnetically anisotropic and effectively respond to magnetic fields that are ˜103 times smaller than other existing work (˜105 G). We anticipate this work will pave the way for effective property enhancement and bulk application of CNT-polymer nanocomposites, through controlled micro-structure and scalable manufacturing.

  11. Carbon nanotube-hydroxyapatite nanocomposite: a novel platform for glucose/O2 biofuel cell.

    Science.gov (United States)

    Zhao, H Y; Zhou, H M; Zhang, J X; Zheng, W; Zheng, Y F

    2009-10-15

    This study demonstrates a novel carbon nanotubes-hydroxyapatite (CNTs-HA) nanocomposite-based compartment-less glucose/O(2) biofuel cell (BFC) with the glucose oxidase (GOD) as the anodic biocatalysts and the laccase as the cathodic biocatalysts. CNTs-HA nanocomposite prepared by the self-assembly method via an aqueous solution reaction has been used as the co-immobilization matrix to incorporate biocatalysts, i.e. GOD and laccase successfully. Moreover, the three-dimensional configuration of the CNTs-HA films electrode would be advantageous to the glucose oxidation on the bioanode and O(2) electroreduction on the biocathode of BFC. The maximum power density delivered by the assembled glucose/O(2) BFC could reach 15.8 muWcm(-2) at a cell voltage of 0.28 V with 10 mM glucose. The results indicate that the CNTs-HA nanocomposite is believed to be very useful for the development of novel BFC device.

  12. Carbon nanotube-hydroxyapatite nanocomposite: a novel platform for glucose/O2 biofuel cell.

    Science.gov (United States)

    Zhao, H Y; Zhou, H M; Zhang, J X; Zheng, W; Zheng, Y F

    2009-10-15

    This study demonstrates a novel carbon nanotubes-hydroxyapatite (CNTs-HA) nanocomposite-based compartment-less glucose/O(2) biofuel cell (BFC) with the glucose oxidase (GOD) as the anodic biocatalysts and the laccase as the cathodic biocatalysts. CNTs-HA nanocomposite prepared by the self-assembly method via an aqueous solution reaction has been used as the co-immobilization matrix to incorporate biocatalysts, i.e. GOD and laccase successfully. Moreover, the three-dimensional configuration of the CNTs-HA films electrode would be advantageous to the glucose oxidation on the bioanode and O(2) electroreduction on the biocathode of BFC. The maximum power density delivered by the assembled glucose/O(2) BFC could reach 15.8 muWcm(-2) at a cell voltage of 0.28 V with 10 mM glucose. The results indicate that the CNTs-HA nanocomposite is believed to be very useful for the development of novel BFC device. PMID:19713096

  13. Novel MnOOH–graphene nanocomposites: Preparation, characterization and electrochemical properties for supercapacitors

    International Nuclear Information System (INIS)

    In this paper, we report a simple and controlled synthesis of novel MnOOH–graphene nanocomposites with a one-step facile hydrothermal method. It is template-free and easy to reproduce. Electrochemical properties are investigated in different media. The values of specific capacitance achieved are 112 F g−1 in 1 M Na2SO4 and 165 F g−1 in 6 M KOH electrolyte, respectively. The assembly of multiple branched MnOOH and graphene flakes results in synergistic effects, forming new electron transfer channels to accelerate electron transfer and provide the pseudocapacitance to increase the overall capacitance. The novel composites have potential applications in the fields of supercapacitors, lithium battery and so on. - Graphical abstract: The MnOOH–graphene nanocomposites shows better specific capacitance with the values achieved 112 F g−1 in 1 M Na2SO4 and 165 F g−1 in 6 M KOH electrolyte, respectively. - Highlights: • Novel MnOOH–graphene nanocomposites were prepared by a one-step hydrothermal method. • The assembly can form new electron transfer channels to accelerate electron transfer. • The capacitive and rate performances are enhanced in both neutral and alkaline medium

  14. Novel MnOOH–graphene nanocomposites: Preparation, characterization and electrochemical properties for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Jun; Zhang, Long, E-mail: zhanglongzhl@163.com

    2015-01-15

    In this paper, we report a simple and controlled synthesis of novel MnOOH–graphene nanocomposites with a one-step facile hydrothermal method. It is template-free and easy to reproduce. Electrochemical properties are investigated in different media. The values of specific capacitance achieved are 112 F g{sup −1} in 1 M Na{sub 2}SO{sub 4} and 165 F g{sup −1} in 6 M KOH electrolyte, respectively. The assembly of multiple branched MnOOH and graphene flakes results in synergistic effects, forming new electron transfer channels to accelerate electron transfer and provide the pseudocapacitance to increase the overall capacitance. The novel composites have potential applications in the fields of supercapacitors, lithium battery and so on. - Graphical abstract: The MnOOH–graphene nanocomposites shows better specific capacitance with the values achieved 112 F g{sup −1} in 1 M Na{sub 2}SO{sub 4} and 165 F g{sup −1} in 6 M KOH electrolyte, respectively. - Highlights: • Novel MnOOH–graphene nanocomposites were prepared by a one-step hydrothermal method. • The assembly can form new electron transfer channels to accelerate electron transfer. • The capacitive and rate performances are enhanced in both neutral and alkaline medium.

  15. Wide-Bandgap Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chinthavali, M.S.

    2005-11-22

    With the increase in demand for more efficient, higher-power, and higher-temperature operation of power converters, design engineers face the challenge of increasing the efficiency and power density of converters [1, 2]. Development in power semiconductors is vital for achieving the design goals set by the industry. Silicon (Si) power devices have reached their theoretical limits in terms of higher-temperature and higher-power operation by virtue of the physical properties of the material. To overcome these limitations, research has focused on wide-bandgap materials such as silicon carbide (SiC), gallium nitride (GaN), and diamond because of their superior material advantages such as large bandgap, high thermal conductivity, and high critical breakdown field strength. Diamond is the ultimate material for power devices because of its greater than tenfold improvement in electrical properties compared with silicon; however, it is more suited for higher-voltage (grid level) higher-power applications based on the intrinsic properties of the material [3]. GaN and SiC power devices have similar performance improvements over Si power devices. GaN performs only slightly better than SiC. Both SiC and GaN have processing issues that need to be resolved before they can seriously challenge Si power devices; however, SiC is at a more technically advanced stage than GaN. SiC is considered to be the best transition material for future power devices before high-power diamond device technology matures. Since SiC power devices have lower losses than Si devices, SiC-based power converters are more efficient. With the high-temperature operation capability of SiC, thermal management requirements are reduced; therefore, a smaller heat sink would be sufficient. In addition, since SiC power devices can be switched at higher frequencies, smaller passive components are required in power converters. Smaller heat sinks and passive components result in higher-power-density power converters

  16. General Assembly

    CERN Multimedia

    Staff Association

    2015-01-01

    Mardi 5 mai à 11 h 00 Salle 13-2-005 Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : 1- Adoption de l’ordre du jour. 2- Approbation du procès-verbal de l’Assemblée générale ordinaire du 22 mai 2014. 3- Présentation et approbation du rapport d’activités 2014. 4- Présentation et approbation du rapport financier 2014. 5- Présentation et approbation du rapport des vérificateurs aux comptes pour 2014. 6- Programme 2015. 7- Présentation et approbation du projet de budget 2015 et taux de cotisation pour 2015. 8- Pas de modifications aux Statuts de l'Association du personnel proposée. 9- Élections des membres de la Commission é...

  17. General assembly

    CERN Multimedia

    Staff Association

    2015-01-01

    Mardi 5 mai à 11 h 00 Salle 13-2-005 Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : Adoption de l’ordre du jour. Approbation du procès-verbal de l’Assemblée générale ordinaire du 22 mai 2014. Présentation et approbation du rapport d’activités 2014. Présentation et approbation du rapport financier 2014. Présentation et approbation du rapport des vérificateurs aux comptes pour 2014. Programme 2015. Présentation et approbation du projet de budget 2015 et taux de cotisation pour 2015. Pas de modifications aux Statuts de l'Association du personnel proposée. Élections des membres de la Commission électorale. &am...

  18. General Assembly

    CERN Multimedia

    Staff Association

    2016-01-01

    Mardi 5 avril à 11 h 00 BE Auditorium Meyrin (6-2-024) Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : Adoption de l’ordre du jour. Approbation du procès-verbal de l’Assemblée générale ordinaire du 5 mai 2015. Présentation et approbation du rapport d’activités 2015. Présentation et approbation du rapport financier 2015. Présentation et approbation du rapport des vérificateurs aux comptes pour 2015. Programme de travail 2016. Présentation et approbation du projet de budget 2016 Approbation du taux de cotisation pour 2017. Modifications aux Statuts de l'Association du personnel proposée. Élections des membres de la Commissio...

  19. Effective Optical Properties of Plasmonic Nanocomposites

    Directory of Open Access Journals (Sweden)

    Christoph Etrich

    2014-01-01

    Full Text Available Plasmonic nanocomposites find many applications, such as nanometric coatings in emerging fields, such as optotronics, photovoltaics or integrated optics. To make use of their ability to affect light propagation in an unprecedented manner, plasmonic nanocomposites should consist of densely packed metallic nanoparticles. This causes a major challenge for their theoretical description, since the reliable assignment of effective optical properties with established effective medium theories is no longer possible. Established theories, e.g., the Maxwell-Garnett formalism, are only applicable for strongly diluted nanocomposites. This effective description, however, is a prerequisite to consider plasmonic nanocomposites in the design of optical devices. Here, we mitigate this problem and use full wave optical simulations to assign effective properties to plasmonic nanocomposites with filling fractions close to the percolation threshold. We show that these effective properties can be used to properly predict the optical action of functional devices that contain nanocomposites in their design. With this contribution we pave the way to consider plasmonic nanocomposites comparably to ordinary materials in the design of optical elements.

  20. Microfluidic assisted one-step fabrication of porous silicon@acetalated dextran nanocomposites for precisely controlled combination chemotherapy.

    Science.gov (United States)

    Liu, Dongfei; Zhang, Hongbo; Mäkilä, Ermei; Fan, Jin; Herranz-Blanco, Bárbara; Wang, Chang-Fang; Rosa, Ricardo; Ribeiro, António J; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

    2015-01-01

    An advanced nanocomposite consisting of an encapsulated porous silicon (PSi) nanoparticle and an acid-degradable acetalated dextran (AcDX) matrix (nano-in-nano), was efficiently fabricated by a one-step microfluidic self-assembly approach. The obtained nano-in-nano PSi@AcDX composites showed improved surface smoothness, homogeneous size distribution, and considerably enhanced cytocompatibility. Furthermore, multiple drugs with different physicochemical properties have been simultaneously loaded into the nanocomposites with a ratiometric control. The release kinetics of all the payloads was predominantly controlled by the decomposition rate of the outer AcDX matrix. To facilitate the intracellular drug delivery, a nona-arginine cell-penetrating peptide (CPP) was chemically conjugated onto the surface of the nanocomposites by oxime click chemistry. Taking advantage of the significantly improved cell uptake, the proliferation of two breast cancer cell lines was markedly inhibited by the CPP-functionalized multidrug-loaded nanocomposites. Overall, this nano-in-nano PSi@polymer composite prepared by the microfluidic self-assembly approach is a universal platform for nanoparticles encapsulation and precisely controlled combination chemotherapy.

  1. Stable polydiacetylene/ZnO nanocomposites with two-steps reversible and irreversible thermochromism: the influence of strong surface anchoring.

    Science.gov (United States)

    Traiphol, Nisanart; Rungruangviriya, Nopparat; Potai, Ruttayapon; Traiphol, Rakchart

    2011-04-15

    This contribution introduces a versatile method to prepare a new class of polydiacetylene(PDA)-based material. ZnO nanoparticle is used as a nano-substrate for spontaneous assembling of diacetylene monomer, 10,12-pentacosadiynoic acid, on its surface. An irradiation of the organized assemblies by UV light results in PDA/ZnO nanocomposites with deep blue color. Strong ionic interaction and hydrogen bonding at the ZnO surface restrict the dynamics of alkyl side chains and promote the PDA ordering, which in turn drastically affects its thermochromic behaviors. We have found that the PDA/ZnO nanocomposite exhibits two-steps color transition upon increasing temperature. The first transition of the nanocomposite in aqueous suspension, causing the color change from blue to purple, occurs reversibly at ∼90°C. The transition temperature shifts to ∼100°C when the nanocomposite is embedded in polyvinyl alcohol matrix. Further increasing temperature to 145°C induces the second transition, which causes irreversible color change from purple to red. PMID:21306726

  2. Self-assembled nanolaminate coatings (SV)

    Energy Technology Data Exchange (ETDEWEB)

    Fan, H.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Aeronautics (LM Aero) are collaborating to develop affordable, self-assembled, nanocomposite coatings and associated fabrication processes that will be tailored to Lockheed Martin product requirements. The purpose of this project is to develop a family of self-assembled coatings with properties tailored to specific performance requirements, such as antireflective (AR) optics, using Sandia-developed self-assembled techniques. The project met its objectives by development of a simple and economic self-assembly processes to fabricate multifunctional coatings. Specifically, materials, functionalization methods, and associated coating processes for single layer and multiple layers coatings have been developed to accomplish high reflective coatings, hydrophobic coatings, and anti-reflective coatings. Associated modeling and simulations have been developed to guide the coating designs for optimum optical performance. The accomplishments result in significant advantages of reduced costs, increased manufacturing freedom/producibility, improved logistics, and the incorporation of new technology solutions not possible with conventional technologies. These self-assembled coatings with tailored properties will significantly address LMC's needs and give LMC a significant competitive lead in new engineered materials. This work complements SNL's LDRD and BES programs aimed at developing multifunctional nanomaterials for microelectronics and optics as well as structure/property investigations of self-assembled nanomaterials. In addition, this project will provide SNL with new opportunities to develop and apply self-assembled nanocomposite optical coatings for use in the wavelength ranges of 3-5 and 8-12 micrometers, ranges of vital importance to military-based sensors and weapons. The SANC technologies will be applied to multiple programs within the LM Company including the F-35, F-22, ADP (Future Strike Bomber

  3. Assembly and actuation of nanomaterials using active biomolecules.

    Energy Technology Data Exchange (ETDEWEB)

    Spoerke, Erik David; Thayer, Gayle Echo; de Boer, Maarten Pieter; Bunker, Bruce Conrad; Liu, Jun; Corwin, Alex David; Gaudioso, Jennifer Marie; Sasaki, Darryl Yoshio; Boal, Andrew Kiskadden; Bachand, George David; Trent, Amanda M.; Bachand, Marlene; Rivera, Susan B.; Koch, Steven John

    2005-11-01

    The formation and functions of living materials and organisms are fundamentally different from those of synthetic materials and devices. Synthetic materials tend to have static structures, and are not capable of adapting to the functional needs of changing environments. In contrast, living systems utilize energy to create, heal, reconfigure, and dismantle materials in a dynamic, non-equilibrium fashion. The overall goal of the project was to organize and reconfigure functional assemblies of nanoparticles using strategies that mimic those found in living systems. Active assembly of nanostructures was studied using active biomolecules to drive the organization and assembly of nanocomposite materials. In this system, kinesin motor proteins and microtubules were used to direct the transport and interactions of nanoparticles at synthetic interfaces. In addition, the kinesin/microtubule transport system was used to actively assemble nanocomposite materials capable of storing significant elastic energy. Novel biophysical measurement tools were also developed for measuring the collective force generated by kinesin motor proteins, which will provide insight on the mechanical constraints of active assembly processes. Responsive reconfiguration of nanostructures was studied in terms of using active biomolecules to mediate the optical properties of quantum dot (QD) arrays through modulation of inter-particle spacing and associated energy transfer interaction. Design rules for kinesin-based transport of a wide range of nanoscale cargo (e.g., nanocrystal quantum dots, micron-sized polymer spheres) were developed. Three-dimensional microtubule organizing centers were assembled in which the polar orientation of the microtubules was controlled by a multi-staged assembly process. Overall, a number of enabling technologies were developed over the course of this project, and will drive the exploitation of energy-driven processes to regulate the assembly, disassembly, and dynamic

  4. A facile strategy to prepare monodisperse nanocrystals with initiative assembly into superlattice

    Institute of Scientific and Technical Information of China (English)

    Qian Zhao; Jiatao Zhang; Hesun Zhu

    2013-01-01

    A facile green strategy, low temperature in-situ chemical conversion, is reported to prepare nanocrystals with initiative “bottom-up” assembly into large-scale superlattice. The appropriate organic chalcogen precursors were chosen to control the kinetics of these reactions to keep monodisperse morphology. They also provide the capping ligands to acquire van der Waals interactions between ligands and dipole moment to self-assemble into large-scale superlattice. This strategy could flexibly modulate the composition of semiconductor nanostructures, such as cations, anions and even the heterostructures with metal nanoparticles. This bottom-up assembly behavior is necessary for the development of optoelectronic devices of II-VI semiconductor nanocrystals.

  5. The Utility of Nanocomposites in Fire Retardancy

    Directory of Open Access Journals (Sweden)

    Charles A. Wilkie

    2010-09-01

    Full Text Available Nanocomposites have been shown to significantly reduce the peak heat release rate, as measured by cone calorimetry, for many polymers but they typically have no effect on the oxygen index or the UL-94 classification. In this review, we will cover what is known about the processes by which nanocomposite formation may bring this about. Montmorillonite will be the focus in this paper but attention will also be devoted to other materials, including carbon nanotubes and layered double hydroxides. A second section will be devoted to combinations of nanocomposite formation with conventional (and unconventional fire retardants. The paper will conclude with a section attempting to forecast the future.

  6. Biomimetic magnetic nanocomposite for smart skins

    KAUST Repository

    Alfadhel, Ahmed

    2015-11-01

    We report a biomimetic tactile sensor consisting of magnetic nanocomposite artificial cilia and magnetic sensors. The nanocomposite is fashioned from polydimethylsiloxane and iron nanowires and exhibits a permanent magnetic behavior. This enables remote operation without an additional magnetic field to magnetize the nanowires, which simplifies device integration. Moreover, the highly elastic and easy patternable nanocomposite is corrosion resistant and thermally stable. The highly sensitive and power efficient tactile sensors can detect vertical and shear forces from interactions with objects. The sensors can operate in dry and wet environment with the ability to measure different properties such as the texture and the movement or stability of objects, with easily adjustable performance.

  7. Ca2+-induced self-assembly of Bombyx mori silk sericin into a nanofibrous network-like protein matrix for directing controlled nucleation of hydroxylapatite nano-needles

    OpenAIRE

    Yang, Mingying; Zhou, Guanshan; Shuai, Yajun; Wang, Jie; Zhu, Liangjun; Mao, Chuanbin

    2015-01-01

    Bone biomineralization is a well-regulated protein-mediated process where hydroxylapatite (HAP) crystals are nucleated with preferred orientation within self-assembled protein matrix. Mimicking this process is a promising approach to the production of bone-like protein/mineral nanocomposites for bone repair and regeneration. Towards the goal of fabricating such nanocomposites from sericin, a protein spun by Bombyx mori (B.mori) silkworm, and bone mineral HAP, for the first time we investigate...

  8. Refractive Indices of Semiconductors from Energy gaps

    CERN Document Server

    Tripathy, S K

    2015-01-01

    An empirical relation based on energy gap and refractive index data has been proposed in the present study to calculate the refractive index of semiconductors. The proposed model is then applied to binary as well as ternary semiconductors for a wide range of energy gap. Using the relation, dielectric constants of some III-V group semiconductors are calculated. The calculated values for different group of binary semiconductors, alkali halides and ternary semiconductors fairly agree with other calculations and known values over a wide range of energy gap. The temperature variation of refractive index for some binary semiconductors have been calculated.

  9. Patterned self-assembled film guided electrodeposition

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Feng; LI; Bin; XU; Tao; CHEN; Miao; HAO; Jingcheng; LI

    2004-01-01

    The paper describes the fabrication of polypyrrole (PPy) microstructures through patterned self-assembled film guided electrodeposition. Thus the patterned self-assembled monolayer is prepared by microcontact printing (μCP) and used as the template in the electrodeposition of PPy. It has been found that the self-assembled monolayer plays completely different roles on different substrates in directing the deposition of the PPy. Namely, the electrodeposition mainly occurs on the exposed area of the gold substrates patterned with dodecanethiol (DDT) and octadecanelthiol (ODT) and on the indium tin oxide (ITO) substrate patterned with octadecyltrichlorosilane (OTS), while PPy nucleates on the OTS covered area and no deposition is found on the exposed area of a semiconductor substrate (silicon). This is attributed to the cooperative effect between the substrate conductivity and the compatibility of the PPy oligomer with the covered or exposed area of the substrate surface.

  10. Plasmonic luminescent core-shell nanocomposites-enhanced chemiluminescence arising from the decomposition of peroxomonosulfite

    Science.gov (United States)

    Chen, Hui; Xue, Wei; Lu, Chao; Li, Hai-fang; Zheng, Yongzan; Lin, Jin-Ming

    2013-12-01

    A core-shell structure of plasmonic luminescent nanocomposite, Ni@SiO2@FITC@SiO2 (NSFS) combining the stable luminescence of fluorophore with the excellent plasmonic property of metal nanomaterials, has been synthesized through layer-by-layer assembly. The effect of NSFS on the ultraweak chemiluminescence (CL) reaction of hydrogen peroxide (H2O2) and sodium bisulfite (NaHSO3) was explored for the first time. It was found that the CL intensity from the decomposition of peroxomonosulfite was significantly enhanced by NSFS. The mechanism of the nanocomposite-enhanced CL was revealed as the coupling of chemically induced excited states of fluorescein isothiocyanate (FITC) with surface plasmons of Ni nanoparticles based on studies of CL emission spectra, electron spin resonance spectra, extinction spectra and fluorescence spectra. The work sheds new light on the characteristics of the versatile materials and gives us new insight into the optical properties of fluorophores.

  11. New strain states and radical property tuning of metal oxides using a nanocomposite thin film approach

    Directory of Open Access Journals (Sweden)

    Judith MacManus-Driscoll

    2015-06-01

    Full Text Available Auxetic-like strain states were generated in self-assembled nanocomposite thin films of (Ba0.6Sr0.4TiO31−x − (Sm2O3x(BSTO − SmO. A switch from auxetic-like to elastic-like strain behavior was observed for x > 0.50, when the SmO switched from being nanopillars in the BSTO matrix to being the matrix with BSTO nanopillars embedded in it. A simple model was adopted to explain how in-plane strain varies with x. At high x (0.75, strongly enhanced ferroelectric properties were obtained compared to pure BSTO films. The nanocomposite method represents a powerful new way to tune the properties of a wide range of strongly correlated metal oxides whose properties are very sensitive to strain.

  12. Electrical conductivity of activated carbon-metal oxide nanocomposites under compression: a comparison study.

    Science.gov (United States)

    Barroso-Bogeat, A; Alexandre-Franco, M; Fernández-González, C; Macías-García, A; Gómez-Serrano, V

    2014-12-01

    From a granular commercial activated carbon (AC) and six metal oxide (Al2O3, Fe2O3, SnO2, TiO2, WO3 and ZnO) precursors, two series of AC-metal oxide nanocomposites were prepared by wet impregnation, oven-drying at 120 °C, and subsequent heat treatment at 200 or 850 °C in an inert atmosphere. Here, the electrical conductivity of the resulting products was studied under moderate compression. The influence of the applied pressure, sample volume, mechanical work, and density of the hybrid materials was thoroughly investigated. The DC electrical conductivity of the compressed samples was measured at room temperature by the four-probe method. Compaction assays suggest that the mechanical properties of the nanocomposites are largely determined by the carbon matrix. Both the decrease in volume and the increase in density were relatively small and only significant at pressures lower than 100 kPa for AC and most nanocomposites. In contrast, the bulk electrical conductivity of the hybrid materials was strongly influenced by the intrinsic conductivity, mean crystallite size, content and chemical nature of the supported phases, which ultimately depend on the metal oxide precursor and heat treatment temperature. The supported nanoparticles may be considered to act as electrical switches either hindering or favouring the effective electron transport between the AC cores of neighbouring composite particles in contact under compression. Conductivity values as a rule were lower for the nanocomposites than for the raw AC, all of them falling in the range of semiconductor materials. With the increase in heat treatment temperature, the trend is toward the improvement of conductivity due to the increase in the crystallite size and, in some cases, to the formation of metals in the elemental state and even metal carbides. The patterns of variation of the electrical conductivity with pressure and mechanical work were slightly similar, thus suggesting the predominance of the pressure

  13. Controlled Growth of Ultrathin Film of Organic Semiconductors by Balancing the Competitive Processes in Dip-Coating for Organic Transistors.

    Science.gov (United States)

    Wu, Kunjie; Li, Hongwei; Li, Liqiang; Zhang, Suna; Chen, Xiaosong; Xu, Zeyang; Zhang, Xi; Hu, Wenping; Chi, Lifeng; Gao, Xike; Meng, Yancheng

    2016-06-28

    Ultrathin film with thickness below 15 nm of organic semiconductors provides excellent platform for some fundamental research and practical applications in the field of organic electronics. However, it is quite challenging to develop a general principle for the growth of uniform and continuous ultrathin film over large area. Dip-coating is a useful technique to prepare diverse structures of organic semiconductors, but the assembly of organic semiconductors in dip-coating is quite complicated, and there are no reports about the core rules for the growth of ultrathin film via dip-coating until now. In this work, we develop a general strategy for the growth of ultrathin film of organic semiconductor via dip-coating, which provides a relatively facile model to analyze the growth behavior. The balance between the three direct factors (nucleation rate, assembly rate, and recession rate) is the key to determine the growth of ultrathin film. Under the direction of this rule, ultrathin films of four organic semiconductors are obtained. The field-effect transistors constructed on the ultrathin film show good field-effect property. This work provides a general principle and systematic guideline to prepare ultrathin film of organic semiconductors via dip-coating, which would be highly meaningful for organic electronics as well as for the assembly of other materials via solution processes. PMID:27267545

  14. Controlled Growth of Ultrathin Film of Organic Semiconductors by Balancing the Competitive Processes in Dip-Coating for Organic Transistors.

    Science.gov (United States)

    Wu, Kunjie; Li, Hongwei; Li, Liqiang; Zhang, Suna; Chen, Xiaosong; Xu, Zeyang; Zhang, Xi; Hu, Wenping; Chi, Lifeng; Gao, Xike; Meng, Yancheng

    2016-06-28

    Ultrathin film with thickness below 15 nm of organic semiconductors provides excellent platform for some fundamental research and practical applications in the field of organic electronics. However, it is quite challenging to develop a general principle for the growth of uniform and continuous ultrathin film over large area. Dip-coating is a useful technique to prepare diverse structures of organic semiconductors, but the assembly of organic semiconductors in dip-coating is quite complicated, and there are no reports about the core rules for the growth of ultrathin film via dip-coating until now. In this work, we develop a general strategy for the growth of ultrathin film of organic semiconductor via dip-coating, which provides a relatively facile model to analyze the growth behavior. The balance between the three direct factors (nucleation rate, assembly rate, and recession rate) is the key to determine the growth of ultrathin film. Under the direction of this rule, ultrathin films of four organic semiconductors are obtained. The field-effect transistors constructed on the ultrathin film show good field-effect property. This work provides a general principle and systematic guideline to prepare ultrathin film of organic semiconductors via dip-coating, which would be highly meaningful for organic electronics as well as for the assembly of other materials via solution processes.

  15. Optical and electrochemical studies of polyaniline/SnO2 fibrous nanocomposites

    International Nuclear Information System (INIS)

    Graphical abstract: Fiber with porous like structure of PANI/SnO2 nanocomposites were prepared by simplest in situ chemical polymerization method. The PL emission spectra revealed that the band from 404 and 436 nm which is related with oxygen vacancies. The excellent electrochemical properties of composite electrode show the specific capacitance of 173 F/g at a scan rate of 25 m V/s. Display Omitted Highlights: ► Self assembled PANI/SnO2 nanocomposites were synthesized by simple polymerization method. ► Electrochemical behavior of PANI/SnO2 nanocomposites electrode was analyzed by CV. ► Nanocomposites exhibit a higher specific capacitance of 173 F/g, compared with pure SnO2. -- Abstract: Polyaniline (PANI)/tin oxide (SnO2) fibrous nanocomposites were successfully prepared by an in situ chemical polymerization method with suitable conditions. The obtained composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, photoluminescence (PL), electrical conductivity and cyclic voltammetry studies (CV). The XRD pattern of the as-prepared sample shows the presence of tetragonal SnO2 and the crystalline structure of SnO2 was not affected with the incorporation of PANI. The FTIR analysis confirms the uniform attachment of PANI on the surface of SnO2 nanostructures. SEM images show a fibrous agglomerated structure of PANI/SnO2. The PL emission spectra revealed that the band from 404 and 436 nm which is related with oxygen vacancies. The electrochemical behavior of the PANI/SnO2 composite electrode was evaluated in a H2SO4 solution using cyclic voltammetry. The composite electrode exhibited a specific capacitance of 173 F/g at a scan rate 25 mV/s. Thus the as-prepared PANI/SnO2 composite shows excellent electrochemical properties, suggesting that this composite is a promising material for supercapacitors.

  16. Closing photoconductive semiconductor switches

    Energy Technology Data Exchange (ETDEWEB)

    Loubriel, G.M.; Zutavern, F.J.; Hjalmarson, H.P.; O' Malley, M.W.

    1989-01-01

    One of the most important limitations of Photoconductive Semiconductor Switches (PCSS) for pulsed power applications is the high laser powers required to activate the switches. In this paper, we discuss recent developments on two different aspects of GaAs PCSS that result in reductions in laser power by a factor of nearly 1000. The advantages of using GaAs over Si are many. First of all, the resistivity of GaAs can be orders of magnitude higher than that of the highest resistivity Si material, thus allowing GaAs switches to withstand dc voltages without thermal runaway. Secondly, GaAs has a higher carrier mobility than Si and, thus, is more efficient (per carrier). Finally, GaAs switches can have naturally fast (ns) opening times at room temperature and low fields, microsecond opening times at liquid nitrogen temperature of 77 K, or, on demand, closing and opening at high fields and room temperature by a mechanism called lock-on (see Ref. 1). By contrast, Si switches typically opening times of milliseconds. The amount of laser light required to trigger GaAs for lock-on, or at 77 K, is about three orders of magnitude lower than at room temperature. In this paper we describe the study of lock-on in GaAs and InP, as well as switching of GaAs at 77 K. We shall show that when GaAs is switched at 77 K, the carrier lifetime is about three orders of magnitude longer than it is at room temperature. We shall explain the change in lifetime in terms of the change in electron capture cross section of the deep levels in GaAs (these are defect or impurity levels in the band gap). In the second section, we describe the lock-on effect, now seen in GaAs and InP, and at fields as high as 70 kV/cm. We show how lock-on can be tailored by changing the GaAs temperature or by neutron bombardment. In the third section, we discuss possible lock-on mechanisms. 5 refs., 5 figs.

  17. Effect of pyrolysis temperature on the properties of carbon/nickel nanocomposites prepared by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Mansour, N. Ben, E-mail: Nabil.Benmansour@fsg.rnu.tn [Laboratory of Physics of Materials and Nanomaterials Applied at Environment (LaPhyMNE), Gabès University, Faculty of Sciences in Gabès, Gabès (Tunisia); Najeh, I.; Mansouri, S. [Laboratory of Physics of Materials and Nanomaterials Applied at Environment (LaPhyMNE), Gabès University, Faculty of Sciences in Gabès, Gabès (Tunisia); El Mir, L. [Laboratory of Physics of Materials and Nanomaterials Applied at Environment (LaPhyMNE), Gabès University, Faculty of Sciences in Gabès, Gabès (Tunisia); Al Imam Mohammad Ibn Saud Islamic University (IMSIU), College of Sciences, Department of Physics, Riyadh 11623 (Saudi Arabia)

    2015-05-15

    Highlights: • Synthesis of nickel oxide nanoparticles in carbon structures. • Presence of multiwall carbon nanotubes (MWNT) around Ni nanoparticles for the sample treated at high pyrolysis temperature. • DC conductivity exhibited the presence of conduction percolation phenomenon and the dominance of conduction model 3D-GVRH in the studied materials. • From AC conductance PF/Ni nanocomposites have two behaviors: semiconductor and metal, depending on the pyrolysis temperature. • Appearance of a negative differential resistance (NDR) at room temperature in the sample treated at 600 °C. - Abstract: Carbon–nickel nanocomposites (C/Ni) were prepared by sol–gel method after the incorporation of nickel oxide (NiO) nanoparticles in organic matrix based on pyrogallol-formaldehyde (PF). The nanocomposites heated under inert atmosphere have been characterized by various techniques such as X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), and electrical analysis. The XRD spectra exhibited the presence of NiO or metallic Ni phase in amorphous carbon matrix at low pyrolysis temperature, while at 1000 °C the graphite structure line was observed. The TEM images indicate the presence of multiwall carbon nanotubes (MWNT) around Ni nanoparticles for the sample treated at high pyrolysis temperature. The AC conductance shows that our nanocomposites have two behaviors: semiconductor and metal, depending on the pyrolysis temperature. The voltage–current V(I) characteristics of the compound show two different regions: an Ohmic region at low current and a negative differential resistance (NDR) region at higher current. This switching phenomenal behavior has been explained by an electrothermal model.

  18. Design of binary SnO2-CuO nanocomposite for efficient photocatalytic degradation of malachite green dye

    Science.gov (United States)

    Kumar, Aniket; Rout, Lipeeka; Achary, L. Satish Kumar; Mohanty, Anurag; Marpally, Jyoshna; Chand, Pradyumna Kumar; Dash, Priyabrat

    2016-04-01

    Semiconductor mediated photocatalysis has got enormous consideration as it has shown immense potential in addressing the overall energy and environmental issues. To overcome the earlier drawbacks concerning quick charge recombination and limited visible-light absorption of semiconductor photocatalysts, numerous methods have been produced in the past couple of decades and the most broadly utilized one is to develop the photocatalytic heterojunctions. In our work, a series of SnO2-CuO nanocomposites of different compositions were synthesized by a combustion method and have been investigated in detail by various characterization techniques, such as wide angle X-ray diffraction (XRD), UV-vis spectroscopy, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The results revealed that the crystal structure and optical properties of the nanocomposites were almost same for all the compositions. FE-SEM images showed that the shape of SnO2-CuO was spherical in nature and the 1: 1 Sn/Cu sample had a well-proportioned morphology. The malachite green dye was used for the photocatalytic studies in a photoreactor and monitored with a UV-visible spectrometer for different composition ratio of metal (Sn: Cu) such as 1:1, 1:2, 2:1, 1:0.5 and 0.5:1. The 1:1 ratio nanocomposite showed excellent photocatalytic degradation of 96 % compared to pure SnO2 and CuO. The mechanism of degradation and charge separation ability of the nanocomposite are also explored using photocurrent measurement study.

  19. Cooperative cytotoxic activity of Zn and Cu in bovine serum albumin-conjugated ZnS/CuS nano-composites in PC12 cancer cells

    International Nuclear Information System (INIS)

    Series of self-assembled and mono-dispersed bovine serum albumin (BSA)-conjugated ZnS/CuS nano-composites with different Zn/Cu ratios had been successfully synthesized by a combination method of the biomimetic synthesis and ion-exchange strategy under the gentle conditions. High-resolution transmission electron microscopy observation, Fourier transform infrared spectra and zeta potential analysis demonstrated that BSA-conjugated ZnS/CuS nano-composites with well dispersity had the hierarchical structure and BSA was a key factor to control the morphology and surface electro-negativity of final products. The real-time monitoring by atomic absorption spectroscopy and powder X-ray diffraction revealed that the Zn/Cu ratio of nano-composites could be controlled by adjusting the ion-exchange time. In addition, the metabolic and morphological assays indicated that the metabolic proliferation and spread of rat pheochromocytoma (PC12) cells could be inhibited by nano-composites, with the high anti-cancer activity at a low concentration (4 ppm). What were more important, Zn and Cu in nano-composites exhibited a positive cooperativity at inhibiting cancer cell functions. The microscope observation and biochemical marker analysis clearly revealed that the nano-composites-included lipid peroxidation and disintegration of membrane led to the death of PC12 cells. Summarily, the present study substantiated the potential of BSA-conjugated ZnS/CuS nano-composites as anti-cancer drug

  20. Facile fabrication of novel silver-polypyrrole-multiwall carbon nanotubes nanocomposite for replacement of platinum in dye-sensitized solar cell

    Science.gov (United States)

    Rafique, Shaista; Sharif, Rehana; Rashid, Imran; Ghani, Sheeba

    2016-08-01

    This paper demonstrates the facile synthesis of high performance silver-polypyrrole-multiwall carbon nanotubes (Ag-PPy-FMWCNTS) nanocomposites via electrodeposition method on stainless steel substrate and its application as a low cost counter electrode (CE) for the precious platinum (Pt) free DSSC. The nanocomposites were characterized by variety of techniques such as Fourier transforms infrared (FTIR), X-ray diffraction, Scanning electron microscope (SEM), cyclic voltammetry (CV) and Four probe technique respectively. The cyclic voltammetry and Tafel polymerization measurements of Ag-PPy-FMWCNTS nanocomposites CE reveal the favorable electrocatalytic activity and low charge transfer resistance Rct(2.50 Ω cm2) for I3-/I- redox solution. The four probe studies showed the large electrical conductivity (226S cm-1) of Ag-PPy-FMWCNTS nanocomposite. The DSSC assembled with Ag-PPy-FMWCNTS nanocomposites CE display the considerable short circuit current density (13.95 mA cm-2) and acceptable solar to electrical conversion efficiency of 7.6%, which is higher to the efficiency of DSSC with thermally decomposed Pt reference electrode 7.1%. The excellent conversion efficiency, rapid charge transfer in combination with low cost and simple fabrication method of Ag-PPy-FMWCNTS nanocomposites can be exploited as an efficient and potential candidate to replace the Pt CE for large scale production of DSSC.

  1. Cooperative cytotoxic activity of Zn and Cu in bovine serum albumin-conjugated ZnS/CuS nano-composites in PC12 cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hua-Jie, E-mail: wanghuajie972001@163.com; Yu, Xue-Hong; Wang, Cai-Feng; Cao, Ying, E-mail: caoying1130@sina.com [Henan Normal University, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, College of Chemistry and Chemical Engineering (China)

    2013-11-15

    Series of self-assembled and mono-dispersed bovine serum albumin (BSA)-conjugated ZnS/CuS nano-composites with different Zn/Cu ratios had been successfully synthesized by a combination method of the biomimetic synthesis and ion-exchange strategy under the gentle conditions. High-resolution transmission electron microscopy observation, Fourier transform infrared spectra and zeta potential analysis demonstrated that BSA-conjugated ZnS/CuS nano-composites with well dispersity had the hierarchical structure and BSA was a key factor to control the morphology and surface electro-negativity of final products. The real-time monitoring by atomic absorption spectroscopy and powder X-ray diffraction revealed that the Zn/Cu ratio of nano-composites could be controlled by adjusting the ion-exchange time. In addition, the metabolic and morphological assays indicated that the metabolic proliferation and spread of rat pheochromocytoma (PC12) cells could be inhibited by nano-composites, with the high anti-cancer activity at a low concentration (4 ppm). What were more important, Zn and Cu in nano-composites exhibited a positive cooperativity at inhibiting cancer cell functions. The microscope observation and biochemical marker analysis clearly revealed that the nano-composites-included lipid peroxidation and disintegration of membrane led to the death of PC12 cells. Summarily, the present study substantiated the potential of BSA-conjugated ZnS/CuS nano-composites as anti-cancer drug.

  2. Electroactive functional hybrid layered nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Destri, Giovanni Li; Torrisi, Vanna; Marletta, Giovanni [Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN) - University of Catania and CSGI - Catania (Italy)

    2012-07-11

    Two methodologies to build new nanostructured hybrid layered nanocomposites are presented. The first one involves the preparation of hybrid metal/polymer nanolayers (NLs) by combining two monolayer preparation techniques: Horizontal Precipitation Langmuir Blodgett method (HP-ML), for copolymer monolayers and sputter deposition technique, for Au NLs deposition. The second methodology is aimed to prepare regular arrays of nanopores, with diameter ranging between 40-100 nm, in ultra-thin films of electroactive polymers, to obtain embedded regular arrays of nanopores filled by a further electroactive organic component. The produced hybrid MLs have been characterized by means of X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and Grazing Incidence X-ray Diffraction (GI-XRD). In the first case, current-voltage (I-V) measurements demonstrate that the multilayers exhibit a bipolar conduction behaviour (electrons and holes carriers), with a peculiar transition in the nature of the majority carriers (from holes to electrons) above a threshold number of bilayers. In the second case, it is found that the degree of pore filling, as well as the polymer crystallinity can be easily modulated, prompting the tuning of the photoresponse of the nanocomposites.

  3. Light-Emitting Polymer Nanocomposites

    Directory of Open Access Journals (Sweden)

    Kyle Gipson

    2011-01-01

    Full Text Available Inorganic nanoparticles doped with optically active rare-earth ions and coated with organic ligands were synthesized in order to create fluorescent polymethyl methacrylate (PMMA nanocomposites. Two different aromatic ligands (acetylsalicylic acid, ASA and 2-picolinic acid, PA were utilized in order to functionalize the surface of Tb3+ : LaF3 nanocrystals. The selected aromatic ligand systems were characterized using infrared spectroscopy, thermal analysis, rheological measurements, and optical spectroscopy. Nanoparticles produced in situ with the PMMA contained on average 10 wt% loading of Tb3+ : LaF3 at a 6 : 1 La : Tb molar ratio and ~7 wt% loading of 4 : 1 La : Tb molar ratio for the PA and ASA systems, respectively. Measured diameters ranged from 457±176 nm to 150±105 nm which is indicative that agglomerates formed during the synthesis process. Both nanocomposites exhibited the characteristic Tb3+ emission peaks upon direct ion excitation (350 nm and ligand excitation (PA : 265 nm and ASA : 275 nm.

  4. Selenium semiconductor core optical fibers

    Directory of Open Access Journals (Sweden)

    G. W. Tang

    2015-02-01

    Full Text Available Phosphate glass-clad optical fibers containing selenium (Se semiconductor core were fabricated using a molten core method. The cores were found to be amorphous as evidenced by X-ray diffraction and corroborated by Micro-Raman spectrum. Elemental analysis across the core/clad interface suggests that there is some diffusion of about 3 wt % oxygen in the core region. Phosphate glass-clad crystalline selenium core optical fibers were obtained by a postdrawing annealing process. A two-cm-long crystalline selenium semiconductor core optical fibers, electrically contacted to external circuitry through the fiber end facets, exhibit a three times change in conductivity between dark and illuminated states. Such crystalline selenium semiconductor core optical fibers have promising utility in optical switch and photoconductivity of optical fiber array.

  5. High mobility emissive organic semiconductor

    Science.gov (United States)

    Liu, Jie; Zhang, Hantang; Dong, Huanli; Meng, Lingqiang; Jiang, Longfeng; Jiang, Lang; Wang, Ying; Yu, Junsheng; Sun, Yanming; Hu, Wenping; Heeger, Alan J.

    2015-12-01

    The integration of high charge carrier mobility and high luminescence in an organic semiconductor is challenging. However, there is need of such materials for organic light-emitting transistors and organic electrically pumped lasers. Here we show a novel organic semiconductor, 2,6-diphenylanthracene (DPA), which exhibits not only high emission with single crystal absolute florescence quantum yield of 41.2% but also high charge carrier mobility with single crystal mobility of 34 cm2 V-1 s-1. Organic light-emitting diodes (OLEDs) based on DPA give pure blue emission with brightness up to 6,627 cd m-2 and turn-on voltage of 2.8 V. 2,6-Diphenylanthracene OLED arrays are successfully driven by DPA field-effect transistor arrays, demonstrating that DPA is a high mobility emissive organic semiconductor with potential in organic optoelectronics.

  6. Organic Semiconductors and its Applications

    Science.gov (United States)

    Kamalasanan, M. N.

    2011-10-01

    Organic semiconductors in the form of evaporated or spin coated thin films have many optoelectronic applications in the present electronic industry. They are frequently used in many type of displays, photo detectors, photoconductors for photocopiers and photovoltaic cells. But many p-conjugated molecules and polymer based devices do not provide satisfactory device performance and operational stability. Most of these problems are related to the interfaces they make with other organic materials and electrodes and the low conductivity of the organic layers. The study of organic-metal and organic—organic interfaces as well as electrical doping of organic semiconductors are very important areas of research at present. In this talk, I will be discussing some of the recent advances in this field as well as some of our own results in the area of interface modification and electrical doping of organic semiconductors.

  7. Catalysts, Protection Layers, and Semiconductors

    DEFF Research Database (Denmark)

    Chorkendorff, Ib

    2015-01-01

    Hydrogen is the simplest solar fuel to produce and in this presentation we shall give a short overview of the pros and cons of various tandem devices [1]. The large band gap semiconductor needs to be in front, but apart from that we can chose to have either the anode in front or back using either...... acid or alkaline conditions. Since most relevant semiconductors are very prone to corrosion the advantage of using buried junctions and using protection layers offering shall be discussed [2-4]. Next we shall discuss the availability of various catalysts for being coupled to these protections layers...... and how their stability may be evaluated [5, 6]. Examples of half-cell reaction using protection layers for both cathode and anode will be discussed though some of recent examples under both alkaline and acidic conditions. Si is a very good low band gap semiconductor and by using TiO2 as a protection...

  8. Crystallization of Organic Semiconductor Molecules in Nanosized Cavities

    DEFF Research Database (Denmark)

    Milita, Silvia; Dionigi, Chiara; Borgatti, Francesco;

    2008-01-01

    The crystallization of an organic semiconductor, viz., tetrahexil-sexithiophene (H4T6) molecules, confined into nanosized cavities of a self-organized polystyrene beads template, has been investigated by means of in situ grazing incidence X-ray diffraction measurements, during the solvent...... evaporation. Thanks to these real time experiments, the phase content and the crystalline domain orientation of H4T6 have been determined, from the onset of the first crystalline molecular assembly to the stable system. The correlation between the bead size dependent crystallization mechanism in this complex...

  9. Second-harmonic imaging of semiconductor quantum dots

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Bozhevolnyi, Sergey I.; Pedersen, Kjeld;

    2000-01-01

    Resonant second-harmonic generation is observed at room temperature in reflection from self-assembled InAlGaAs quantum dots grown on a GaAs (001) substrate. The detected second-harmonic signal peaks at a pump wavelength of similar to 885 nm corresponding to the quantum-dot photoluminescence maxim...... observe that second-harmonic images of the quantum-dot surface structure show wavelength-dependent spatial variations. Imaging at different wavelength is used to demonstrate second-harmonic generation from the semiconductor quantum dots. (C) 2000 American Institute of Physics....

  10. Exciton Transport in Organic Semiconductors

    Science.gov (United States)

    Menke, Stephen Matthew

    Photovoltaic cells based on organic semiconductors are attractive for their use as a renewable energy source owing to their abundant feedstock and compatibility with low-cost coating techniques on flexible substrates. In contrast to photovoltaic cells based traditional inorganic semiconductors, photon absorption in an organic semiconductor results in the formation of a coulombically bound electron-hole pair, or exciton. The transport of excitons, consequently, is of critical importance as excitons mediate the interaction between charge and light in organic photovoltaic cells (OPVs). In this dissertation, a strong connection between the fundamental photophysical parameters that control nanoscopic exciton energy transfer and the mesoscopic exciton transport is established. With this connection in place, strategies for enhancing the typically short length scale for exciton diffusion (L D) can be developed. Dilution of the organic semiconductor boron subphthalocyanine chloride (SubPc) is found to increase the LD for SubPc by 50%. In turn, OPVs based on dilute layers of SubPc exhibit a 30% enhancement in power conversion efficiency. The enhancement in power conversion efficiency is realized via enhancements in LD, optimized optical spacing, and directed exciton transport at an exciton permeable interface. The role of spin, energetic disorder, and thermal activation on L D are also addressed. Organic semiconductors that exhibit thermally activated delayed fluorescence and efficient intersystem and reverse intersystem crossing highlight the balance between singlet and triplet exciton energy transfer and diffusion. Temperature dependent measurements for LD provide insight into the inhomogeneously broadened exciton density of states and the thermal nature of exciton energy transfer. Additional topics include energy-cascade OPV architectures and broadband, spectrally tunable photodetectors based on organic semiconductors.

  11. Optical property of nanocomposite of mesoporous silica thin films incorporated with gold nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Jingyue Fang; Xueao Zhang; Shiqiao Qin; Shengli Chang

    2011-01-01

    @@ Amino-functionalized mesoporous silica thin films (MTFs) are produced using surface active agent F127,and then gold nanoparticles are introduced into the pore channels to prepare the Au/SiO2 nanocomposite.After assembling the gold, the amino-functionalized MTF undergoes some shrinkage but remains a periodic structure as demonstrated by X-ray diffraction (XRD) patterns.The nanocomposite shows an acute characteristic diffraction peak assigned to (111) plane of the face-centered-cubic structure of gold,indicating that gold nanoparticles crystallize well and grow in a preferred orientation in the pore channels.The surface plasma resonance (SPR) absorption peak near 570 nm undergoes a red-shift accompanied by a strengthening of intensity when HAuCl4 is used to react with the amino groups on the internal pore surfaces for 4, 6, and 8 h.The simulative results are consistent with the experimental ones shows that the absorption property of the Au/SiO2 nanocomposite is influenced by the dipping time, which affects the size and volume fraction of embedded gold nanoparticles.%Amino-functionalized mesoporous silica thin films (MTFs) are produced using surface active agent F127,and then gold nanoparticles are introduced into the pore channels to prepare the Au/SiO2 nanocomposite. After assembling the gold, the amino-functionalized MTF undergoes some shrinkage but remains a periodic structure as demonstrated by X-ray diffraction (XRD) patterns. The nanocomposite shows an acute characteristic diffraction peak assigned to (111) plane of the face-centered-cubic structure of gold,indicating that gold nanoparticles crystallize well and grow in a preferred orientation in the pore channels.The surface plasma resonance (SPR) absorption peak near 570 nm undergoes a red-shift accompanied by a strengthening of intensity when HAuCl4 is used to react with the amino groups on the internal pore surfaces for 4, 6, and 8 h. The simulative results are consistent with the experimental ones shows

  12. Optical coherent control in semiconductors

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher

    2001-01-01

    The developments with coherent control (CC) techniques in optical spectroscopy have recently demonstrated population control and coherence manipulations when the induced optical phase is explored with phase-locked laser pulses. These and other developments have been guiding the new research field...... of quantum control including the recent applications to semiconductors and nanostructures. We study the influence of inhomogeneous broadening in semiconductors on CC results. Photoluminescence (PL) and the coherent emission in four-wave mixing (FWM) is recorded after resonant excitation with phase-locked...

  13. Semiconductors and semimetals epitaxial microstructures

    CERN Document Server

    Willardson, Robert K; Beer, Albert C; Gossard, Arthur C

    1994-01-01

    Newly developed semiconductor microstructures can now guide light and electrons resulting in important consequences for state-of-the-art electronic and photonic devices. This volume introduces a new generation of epitaxial microstructures. Special emphasis has been given to atomic control during growth and the interrelationship between the atomic arrangements and the properties of the structures.Key Features* Atomic-level control of semiconductor microstructures* Molecular beam epitaxy, metal-organic chemical vapor deposition* Quantum wells and quantum wires* Lasers, photon(IR)detectors, heterostructure transistors

  14. Wide band gap semiconductor templates

    Energy Technology Data Exchange (ETDEWEB)

    Arendt, Paul N. (Los Alamos, NM); Stan, Liliana (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM); DePaula, Raymond F. (Santa Fe, NM); Usov, Igor O. (Los Alamos, NM)

    2010-12-14

    The present invention relates to a thin film structure based on an epitaxial (111)-oriented rare earth-Group IVB oxide on the cubic (001) MgO terminated surface and the ion-beam-assisted deposition ("IBAD") techniques that are amendable to be over coated by semiconductors with hexagonal crystal structures. The IBAD magnesium oxide ("MgO") technology, in conjunction with certain template materials, is used to fabricate the desired thin film array. Similarly, IBAD MgO with appropriate template layers can be used for semiconductors with cubic type crystal structures.

  15. Bonds and bands in semiconductors

    CERN Document Server

    Phillips, Jim

    2009-01-01

    This classic work on the basic chemistry and solid state physics of semiconducting materials is now updated and improved with new chapters on crystalline and amorphous semiconductors. Written by two of the world's pioneering materials scientists in the development of semiconductors, this work offers in a single-volume an authoritative treatment for the learning and understanding of what makes perhaps the world's most important engineered materials actually work. Readers will find: --' The essential principles of chemical bonding, electron energy bands and their relationship to conductive and s

  16. The Novel Semiconductor Nanowire Heterostructures

    Institute of Scientific and Technical Information of China (English)

    J.Q.Hu; Y.Bando; J.H.Zhan; D.Golberg

    2007-01-01

    1 Results If one-dimensional heterostructures with a well-defined compositional profile along the wire radial or axial direction can be realized within semiconductor nanowires, new nano-electronic devices,such as nano-waveguide and nano-capcipator, might be obtained. Here,we report the novel semiconducting nanowire heterostructures:(1) Si/ZnS side-to-side biaxial nanowires and ZnS/Si/ZnS sandwich-like triaxial nanowires[1],(2) Ga-Mg3N2 and Ga-ZnS metal-semiconductor nanowire heterojunctions[2-3]and (3) ...

  17. Electronic Structure of Semiconductor Nanocrystals

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.

  18. Introduction to semiconductor manufacturing technology

    CERN Document Server

    2012-01-01

    IC chip manufacturing processes, such as photolithography, etch, CVD, PVD, CMP, ion implantation, RTP, inspection, and metrology, are complex methods that draw upon many disciplines. [i]Introduction to Semiconductor Manufacturing Technologies, Second Edition[/i] thoroughly describes the complicated processes with minimal mathematics, chemistry, and physics; it covers advanced concepts while keeping the contents accessible to readers without advanced degrees. Designed as a textbook for college students, this book provides a realistic picture of the semiconductor industry and an in-depth discuss

  19. Organic semiconductors in sensor applications

    CERN Document Server

    Malliaras, George; Owens, Róisín

    2008-01-01

    Organic semiconductors offer unique characteristics such as tunability of electronic properties via chemical synthesis, compatibility with mechanically flexible substrates, low-cost manufacturing, and facile integration with chemical and biological functionalities. These characteristics have prompted the application of organic semiconductors and their devices in physical, chemical, and biological sensors. This book covers this rapidly emerging field by discussing both optical and electrical sensor concepts. Novel transducers based on organic light-emitting diodes and organic thin-film transistors, as well as systems-on-a-chip architectures are presented. Functionalization techniques to enhance specificity are outlined, and models for the sensor response are described.

  20. The processing of semiconductor materials

    Science.gov (United States)

    1979-01-01

    Five experiments involving the processing of semiconductor materials were performed during the Skylab mission. After discussions on semiconductors and their unique electronic properties, and techniques of crystal growth, these five experiments are presented. Four melt growth experiments were attempted: (1) steady state growth and segregation under zero gravity (InSb); (2) seeded, containerless solidification of InSb; (3) influence of gravity-free solidification on microsegregation; and (4) directional solidification of InSb-GaSb alloys. One vapor growth experiment, crystal growth by vapor transport, was attempted.

  1. Modeling of semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Mørk, Jesper; Bischoff, Svend; Berg, Tommy Winther;

    We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed.......We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed....

  2. Nanocomposite polymer electrolyte for rechargeable magnesium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yuyan; Rajput, Nav Nidhi; Hu, Jian Z.; Hu, Mary Y.; Liu, Tianbiao L.; Wei, Zhehao; Gu, Meng; Deng, Xuchu; Xu, Suochang; Han, Kee Sung; Wang, Jiulin; Nie, Zimin; Li, Guosheng; Zavadil, K.; Xiao, Jie; Wang, Chong M.; Henderson, Wesley A.; Zhang, Jiguang; Wang, Yong; Mueller, Karl T.; Persson, Kristin A.; Liu, Jun

    2014-12-28

    Nanocomposite polymer electrolytes present new opportunities for rechargeable magnesium batteries. However, few polymer electrolytes have demonstrated reversible Mg deposition/dissolution and those that have still contain volatile liquids such as tetrahydrofuran (THF). In this work, we report a nanocomposite polymer electrolyte based on poly(ethylene oxide) (PEO), Mg(BH4)2 and MgO nanoparticles for rechargeable Mg batteries. Cells with this electrolyte have a high coulombic efficiency of 98% for Mg plating/stripping and a high cycling stability. Through combined experiment-modeling investigations, a correlation between improved solvation of the salt and solvent chain length, chelation and oxygen denticity is established. Following the same trend, the nanocomposite polymer electrolyte is inferred to enhance the dissociation of the salt Mg(BH4)2 and thus improve the electrochemical performance. The insights and design metrics thus obtained may be used in nanocomposite electrolytes for other multivalent systems.

  3. Mechanical strength of carbon nanotube nickel nanocomposites

    Science.gov (United States)

    Sun, Ying; Sun, Jianren; Liu, Miao; Chen, Quanfang

    2007-12-01

    Carbon nanotubes (CNTs), including single-walled CNT (SWCNT) and multi-walled CNT (MWCNT), have been regarded as the stiffest and strongest materials ever developed and are promising reinforcement fillers for developing nanocomposites. However, the scientific community has been puzzled about the reinforcement efficiency. Here we report CNT-reinforced nickel nanocomposites fabricated with an innovative electrochemical co-deposition process for achieving good interfacial bonding between CNT and metallic matrices. Test results show that Ni/SWCNT composite produces a tensile strength as high as 2 GPa, which is more than three times stronger than that of pure nickel. The mechanical strength of Ni/CNT nanocomposites is dependent on CNT addition, while the fracture strain remains similar or better than that of pure nickel. The good reinforcement of CNT/metal nanocomposites is attributed to the good interfacial bonding as well as the stiffer matrix nature.

  4. Electrical conduction of a XLPE nanocomposite

    Science.gov (United States)

    Park, Yong-Jun; Sim, Jae-Yong; Lim, Kee-Joe; Nam, Jin-Ho; Park, Wan-Gi

    2014-07-01

    The resistivity, breakdown strength, and formation of space charges are very important factors for insulation design of HVDC cable. It is known that a nano-sized metal-oxide inorganic filler reduces the formation of space charges in the polymer nanocomposite. Electrical conduction of cross-linked polyethylene(XLPE) nanocomposite insulating material is investigated in this paper. The conduction currents of two kinds of XLPE nanocomposites and XLPE without nano-filler were measured at temperature of 303 ~ 363 K under the applied electric fields of 10 ~ 50 kV/mm. The current of the nanocomposite specimen is smaller than that of XLPE specimen without nano-filler. The conduction mechanism may be explained in terms of Schottky emission and multi-core model.

  5. In situ SU-8 silver nanocomposites

    DEFF Research Database (Denmark)

    Fischer, Søren Vang; Uthuppu, Basil; Jakobsen, Mogens Havsteen

    2015-01-01

    Nanocomposite materials containing metal nanoparticles are of considerable interest in photonics and optoelectronics applications. However, device fabrication of such materials always encounters the challenge of incorporation of preformed nanoparticles into photoresist materials. As a solution...... to this problem, an easy new method of fabricating silver nanocomposites by an in situ reduction of precursors within the epoxy-based photoresist SU-8 has been developed. AgNO3 dissolved in acetonitrile and mixed with the epoxy-based photoresist SU-8 forms silver nanoparticles primarily during the pre- and post...... silver nanocomposite materials can be spin coated as homogeneous thin films and structured by using UV lithography. A resolution of 5 mu m is achieved in the lithographic process. The UV exposure time is found to be independent of the nanoparticle concentration. The fabricated silver nanocomposites...

  6. Large-Strain Transparent Magnetoactive Polymer Nanocomposites

    Science.gov (United States)

    Meador, Michael A.

    2012-01-01

    A document discusses polymer nano - composite superparamagnetic actuators that were prepared by the addition of organically modified superparamagnetic nanoparticles to the polymer matrix. The nanocomposite films exhibited large deformations under a magnetostatic field with a low loading level of 0.1 wt% in a thermoplastic polyurethane elastomer (TPU) matrix. The maximum actuation deformation of the nanocomposite films increased exponentially with increasing nanoparticle concentration. The cyclic deformation actuation of a high-loading magnetic nanocomposite film was examined in a low magnetic field, and it exhibited excellent reproducibility and controllability. Low-loading TPU nanocomposite films (0.1-2 wt%) were transparent to semitransparent in the visible wavelength range, owing to good dispersion of the magnetic nanoparticles. Magnetoactuation phenomena were also demonstrated in a high-modulus, high-temperature polyimide resin with less mechanical deformation.

  7. Cellulose nanocrystals reinforced foamed nitrile rubber nanocomposites.

    Science.gov (United States)

    Chen, Yukun; Zhang, Yuanbing; Xu, Chuanhui; Cao, Xiaodong

    2015-10-01

    Research on foamed nitrile rubber (NBR)/cellulose nanocrystals (CNs) nanocomposites is rarely found in the literatures. In this paper, CNs suspension and NBR latex was mixed to prepared the foamed NBR/CNs nanocomposites. We found that the CNs mainly located in the cell walls, effectively reinforcing the foamed NBR. The strong interaction between the CNs and NBR matrix restricted the mobility of NBR chains surrounding the CNs, hence increasing the crosslink density of the NBR matrix. CNs exhibited excellent reinforcement on the foamed NBR: a remarkable increase nearly 76% in the tensile strength of the foamed nanocomposites was achieved with a load of only 15 phr CNs. Enhanced mechanical properties make the foamed NBR/CNs nanocomposites a promising damping material for industrial applications with a potential to reduce the petroleum consumption. PMID:26076611

  8. Nanocomposites Polarizing by Absorption: Dichroism in the Near-Infrared Region (NIR

    Directory of Open Access Journals (Sweden)

    Lorenz Bonderer

    2014-03-01

    Full Text Available We describe the preparation of nanocomposites which exhibit dichroism in the near infrared region (NIR. These materials consist of crosslinked poly(dimethylsiloxane (PDMS and gold nanoparticles, coated with 1-dodecanethiol or tert-tetradecanethiol. The alkanethiols improve dispersibility of the gold particles, and accordingly composites were manufactured by diffusion of the particles into swollen self-supporting PDMS elastomer films. After drying, the films were exposed to solvents for one minute, stretched in wet state, dried again and annealed. This procedure led to formation of oriented linear gold particle assemblies within stretched polymer. If the aspect ratio of the particle assemblies is high, the absorption of polarized light in the NIR region is expected to depend on the angle between the polarization plane and the orientation direction of the particle assemblies, and this was observed to be the case.

  9. Influence of phonons on semiconductor quantum emission

    Energy Technology Data Exchange (ETDEWEB)

    Feldtmann, Thomas

    2009-07-06

    A microscopic theory of interacting charge carriers, lattice vibrations, and light modes in semiconductor systems is presented. The theory is applied to study quantum dots and phonon-assisted luminescence in bulk semiconductors and heterostructures. (orig.)

  10. Fundamentals of semiconductors physics and materials properties

    CERN Document Server

    Yu, Peter Y

    2005-01-01

    Provides detailed explanations of the electronic, vibrational, transport, and optical properties of semiconductors. This textbook emphasizes understanding the physical properties of Si and similar tetrahedrally coordinated semiconductors and features an extensive collection of tables of material parameters, figures, and problems.

  11. A Biocompatible Nanocomposite for Glucose Sensing

    OpenAIRE

    Parvaneh Rahimi; Hedayatollah Ghourchian; Hossain-Ali Rafiee-Pour; Parviz Norouzi; Mohammad Reza Ganjali

    2011-01-01

    A nanocomposite containing amine functionalized multiwalled carbon nanotubes and a room temperature ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) was prepared and applied for glucose oxidase (GOx) immobilization on glassy carbon electrode. The proposed nanocomposite provided a favorable microenvironment to preserve the bioactivity of GOx. It could also effectively facilitate the enzyme direct electron transfer to the electrode. This brought about a remarkable improvement in the...

  12. Mesoporous metal oxide graphene nanocomposite materials

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jun; Aksay, Ilhan A.; Kou, Rong; Wang, Donghai

    2016-05-24

    A nanocomposite material formed of graphene and a mesoporous metal oxide having a demonstrated specific capacity of more than 200 F/g with particular utility when employed in supercapacitor applications. A method for making these nanocomposite materials by first forming a mixture of graphene, a surfactant, and a metal oxide precursor, precipitating the metal oxide precursor with the surfactant from the mixture to form a mesoporous metal oxide. The mesoporous metal oxide is then deposited onto a surface of the graphene.

  13. Carbon nanotube-polymer nanocomposite infrared sensor.

    Science.gov (United States)

    Pradhan, Basudev; Setyowati, Kristina; Liu, Haiying; Waldeck, David H; Chen, Jian

    2008-04-01

    The infrared photoresponse in the electrical conductivity of single-walled carbon nanotubes (SWNTs) is dramatically enhanced by embedding SWNTs in an electrically and thermally insulating polymer matrix. The conductivity change in a 5 wt % SWNT-polycarbonate nanocomposite is significant (4.26%) and sharp upon infrared illumination in the air at room temperature. While the thermal effect predominates in the infrared photoresponse of a pure SWNT film, the photoeffect predominates in the infrared photoresponse of SWNT-polycarbonate nanocomposites. PMID:18333623

  14. Facile fabrication of mesoporous iron modified Al2O3 nanoparticles pillared montmorillonite nanocomposite: a smart photo-Fenton catalyst for quick removal of organic dyes.

    Science.gov (United States)

    Pradhan, Amaresh C; Varadwaj, G Bishwa Bidita; Parida, K M

    2013-11-14

    A mesoporous iron modified Al2O3 nanoparticle pillared montmorillonite nanocomposite (mesoporous Fe/APM nanocomposite) was synthesized by using sodium exchanged montmorillonite by cation-exchange, gallery-templated synthesis and impregnation method. Formation of Al2O3 nanoparticles (Al2O3 NPs) having average particle size 5.20-6.50 nm within montmorillonite, formation of mesoporous Al2O3 NPs pillared montmorillonite (mesoporous APM) from montmorillonite and formation of a mesoporous Fe/APM nanocomposite signifies the present investigation. The roles of ammonia, CTAB, octyl amine and calcination temperature for fabrication of mesoporous Fe/APM nanocomposite were highly significant. Ammonia was used for post-synthesis treatment, which helped in the formation of micellar assemblies in the interlayer space. The materials were characterized by different techniques such as N2 adsorption-desorption study, which demonstrated the mesoporosity of the material. A transmission electron microscopy (TEM) image proves the morphology and size of the Al2O3 NPs and mesoporous Fe/APM nanocomposites. X-ray diffraction technique (XRD) describes the formation of the pillaring of the Al2O3 NPs within montmorillonite (APM). It has been noted that pure montmorillonite is a micro/mesoporous material. But after pillaring of Al2O3 NPs within the montmorillonite, mesoporosity developed, which is the vital aspect of present investigation. It was observed that the mesoporous Fe/APM nanocomposite has high photo-Fenton activity towards degradation of organic dyes such as acid blue (AB) and reactive blue (RB). Nearly 100% degradation took place within 30 minutes with high concentration of dye (500 mg L(-1)) by mesoporous 5 Fe/APM nanocomposite under ambient conditions. Small particle sizes of nanocomposite, quick reduction of Fe(III) and mesoporosity are the key points for proficient degradation of AB and RB. PMID:24002045

  15. Ultrafast THz Saturable Absorption in Doped Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hoffmann, Matthias C.

    2011-01-01

    We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields.......We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields....

  16. Diode having trenches in a semiconductor region

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, Tomas Apostol; Lu, Bin; Matioli, Elison de Nazareth

    2016-03-22

    An electrode structure is described in which conductive regions are recessed into a semiconductor region. Trenches may be formed in a semiconductor region, such that conductive regions can be formed in the trenches. The electrode structure may be used in semiconductor devices such as field effect transistors or diodes. Nitride-based power semiconductor devices are described including such an electrode structure, which can reduce leakage current and otherwise improve performance.

  17. Semiconductor devices having a recessed electrode structure

    Science.gov (United States)

    Palacios, Tomas Apostol; Lu, Bin; Matioli, Elison de Nazareth

    2015-05-26

    An electrode structure is described in which conductive regions are recessed into a semiconductor region. Trenches may be formed in a semiconductor region, such that conductive regions can be formed in the trenches. The electrode structure may be used in semiconductor devices such as field effect transistors or diodes. Nitride-based power semiconductor devices are described including such an electrode structure, which can reduce leakage current and otherwise improve performance.

  18. Semiconductor nanocrystal-based phagokinetic tracking

    Science.gov (United States)

    Alivisatos, A Paul; Larabell, Carolyn A; Parak, Wolfgang J; Le Gros, Mark; Boudreau, Rosanne

    2014-11-18

    Methods for determining metabolic properties of living cells through the uptake of semiconductor nanocrystals by cells. Generally the methods require a layer of neutral or hydrophilic semiconductor nanocrystals and a layer of cells seeded onto a culture surface and changes in the layer of semiconductor nanocrystals are detected. The observed changes made to the layer of semiconductor nanocrystals can be correlated to such metabolic properties as metastatic potential, cell motility or migration.

  19. Semiconductor assisted metal deposition for nanolithography applications

    Science.gov (United States)

    Rajh, Tijana; Meshkov, Natalia; Nedelijkovic, Jovan M.; Skubal, Laura R.; Tiede, David M.; Thurnauer, Marion

    2001-01-01

    An article of manufacture and method of forming nanoparticle sized material components. A semiconductor oxide substrate includes nanoparticles of semiconductor oxide. A modifier is deposited onto the nanoparticles, and a source of metal ions are deposited in association with the semiconductor and the modifier, the modifier enabling electronic hole scavenging and chelation of the metal ions. The metal ions and modifier are illuminated to cause reduction of the metal ions to metal onto the semiconductor nanoparticles.

  20. Semiconductor electrode with improved photostability characteristics

    Science.gov (United States)

    Frank, Arthur J.

    1987-01-01

    An electrode is disclosed for use in photoelectrochemical cells having an electrolyte which includes an aqueous constituent. The electrode includes a semiconductor and a hydrophobic film disposed between the semiconductor and the aqueous constituent. The hydrophobic film is adapted to permit charges to pass therethrough while substantially decreasing the activity of the aqueous constituent at the semiconductor surface thereby decreasing the photodegradation of the semiconductor electrode.