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Sample records for crystal composite films

  1. Polarization Raman Microscopic Study of Molecular Alignment Behavior in Liquid Crystal/Polymer Composite Films

    Science.gov (United States)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2005-12-01

    We clarified that the molecular alignment of aggregated polymers is partially synchronized with liquid crystal (LC) director reorientation in an LC/polymer composite film. The molecular alignment behavior in composite films with LC- and polymer-rich regions formed by photopolymerization-induced phase separation was investigated using polarization Raman spectral microscopy. Raman scattering intensity induced by aligned side chains of polymers in the LC-rich region changed with LC director reorientation when voltage was applied to the composite film. It was confirmed for the first time that polymers capable of movement are formed in the LC-rich region.

  2. Novel Bi-substituted Yttrium Iron Garnet Film/Crystal Composite for Magneto-optical Applications

    Institute of Scientific and Technical Information of China (English)

    HUANG Min; XU Zhi-cheng; ZHOU Wei-zhen

    2004-01-01

    The novel Bi-substituted rare-earth iron garnet films were grown by the modified liquid phase epitaxy (LPE) technique for use as a 45° Faraday rotator in optical isolators. First, single crystals of Y3 Fe5 O12(YIG), with a lattice constant of 1. 237 8 nm, were grown by means of the Czochralski method. Using the seed crystal of YIG instead of the conventional non-magnetic garnet of Gd3Ga5O12 (GGG) as a substrate,a film of BiYbIG was grown by means of the LPE method from Bi2O3 - B2O3 fluxes. The structural, magnetic and magneto-optical properties of BiYbIG LPE film/YIG crystal composite have been investigated using directional X-ray diffraction (XRD), electron probe microanalysis (EPMA), vibrating sample magnetometer (VMS) and near-infrared transmission spectrometry. The saturation magnetization 4πMs has been estimated to be about 1.2×10 6 A/m. The Faraday rotation spectrum was measured by the method of rotating analyzer ellipsometry (RAE) with the wavelength varied from 800 nm to 1 700 nm. The resultant Bi0.37 Yb2.63 Fe5 O12LPE film/YIG crystal composite showed an increased Faraday rotation coefficient due to doping Bi3+ ions into the dodecahedral sites of the magnetic garnet without increasing absorption loss, therefore a good magnetooptic figure of merit,defined by the ratio of Faraday rotation and optical absorption loss, has been achieved of 21.5 and 30.2 (°)/dB at 1 300 and 1 550 nm wavelengths respectively and room temperature. Since Yb3+ and Y3+ ions provide the opposite contribution to the wideband and temperature characteristics of Faraday rotation,the values of Faraday rotation wavelength and temperature coefficients were reduced to 0.06 %/nm and 0.007(°)/℃ at 1 550 nm wavelength, respectively.

  3. Fabrication and Crystal Structure of Sol-Gel Deposited BST Thin Films with Compositional Gradient

    Directory of Open Access Journals (Sweden)

    Czekaj D.

    2017-06-01

    Full Text Available In the present research technology of compositionally graded barium strontium titanate Ba1-xSrxTiO3 thin films deposited on stainless steel substrates by sol-gel spin coating followed with thermal annealing at T = 650°C is reported. Results of thermal behavior of the sol-gel derived powders with compositions used for fabrication of graded structure (i.e. with Sr mole fraction x = 0.5, 0.4 and 0.3 are described. X-ray diffraction studies of the phase composition and crystal structure of such complex thin film configuration are given. It was found that gel powders exhibited a large total weight loss of about Δm ≈ 44-47%. Three stages of weight loss took place at temperature ranges: below T ≈ 300°C, at ΔT ≈ 300-500°C and between T = 600°C and T = 800°C. Phase analysis has shown that the dominating phase is Ba0.67Sr0.33TiO3 compound while the second phase is Ba0.7Sr0.3TiO3 or Ba0.5Sr0.5TiO3 for “up-graded” and “down-graded” structure, respectively.

  4. Superior environment resistance of quartz crystal microbalance with anatase TiO{sub 2}/ZnO nanorod composite films

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Wei, E-mail: weiqiang.tju@163.com [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin (China); Wei, Li; Shaodan, Wang [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin (China); Yu, Bai [Beijing Institute of Spacecrafts Environment Engineering, Beijing 100094 (China)

    2015-08-30

    Graphical abstract: ZnO nanorod array being prepared by an in situ method on the QCM coated with Au film via hydrothermal process and surface modification with coated TiO{sub 2} by sol–gel methods to form a superhydrophobic TiO{sub 2}/ZnO composite film the anatase TiO{sub 2}/ZnO nanorod composite film with a sharp, pencil-like structure exhibiting excellent superhydrophobicity (water contact angle of 155°), non-sticking water properties, and an autonomous cleaning property under UV irradiation. The anatase TiO{sub 2}/ZnO nanorod composite film facilitates the precise measurement and extended lifetime of the QCM for the detection of organic gas molecules. - Highlights: • This work combines, for the first time, the advantage of the TiO{sub 2}/ZnO composite film on photocatalysis and reversible super-hydrophobic and super-hydrophilic transition, and puts forward a solution to satisfy weatherability of quartz crystal microbalance in long-term application. • The anatase TiO{sub 2}/ZnO nanorod composite film with pencil structure exhibit excellent super-hydrophobicity (water contact angle can reach 155°), no-sticking water properties and self-cleaning property under UV irradiation. • The photocatalysis and reversible super-hydrophobic and super-hydrophilic transition of the TiO{sub 2}/ZnO nanorod composite film is stable in long-term application. - Abstract: The precise measurement of quartz crystal microbalance (QCM) in the detection and weighing of organic gas molecules is achieved due to excellent superhydrophobicity of a deposited film composite. Photocatalysis is utilized as a method for the self-cleaning of organic molecules on the QCM for extended long-term stability in the precision of the instrument. In this paper, ZnO nanorod array is prepared via in situ methods on the QCM coated with Au film via hydrothermal process. Subsequently, a TiO{sub 2}/ZnO composite film is synthesized by surface modification with TiO{sub 2} via sol–gel methods. Results

  5. Compositional analysis of electrodeposited bismuth telluride thermoelectric thin films using combined electrochemical quartz crystal microgravimetry--stripping voltammetry.

    Science.gov (United States)

    Ham, Sunyoung; Jeon, Soyeon; Lee, Ungki; Park, Minsoon; Paeng, Ki-Jung; Myung, Noseung; Rajeshwar, Krishnan

    2008-09-01

    Bismuth telluride (Bi 2Te 3 ) is a benchmark material for thermoelectric power generation and cooling applications. Electrodeposition is a versatile technique for preparing thin films of this material; however, it affords films of variable composition depending on the preparation history. A simple and rapid assay of electrodeposited films, therefore, has both fundamental and practical importance. In this study, a new protocol for the electroanalysis of Bi 2Te 3 thin films is presented by combining the two powerful and complementary techniques of electrochemical quartz crystal microgravimetry (EQCM) and stripping voltammetry. First, any free (and excess) tellurium in the electrodeposited film was reduced to soluble Te ( 2- ) species by scanning to negative potentials in a 0.1 M Na 2SO 4 electrolyte, and the accompanying frequency increase (mass loss) was used to determine the content of free tellurium. The film was again subjected to cathodic stripping in the same medium (to generate Bi (0) and soluble Te (2-) from the Bi 2 Te 3 film component of interest), and the EQCM frequency change was used to determine the content of chemically bound Te in the Bi 2Te 3 thin film and thereby the compound stoichiometry. Finally, the EQCM frequency change during Bi oxidation to Bi (3+) and the difference between total Bi and Bi in Bi 2Te 3 resulted in the assay of free (excess) Bi in the electrodeposited film. Problems associated with the chemical/electrochemical stability of the free Bi species were circumvented by a flow electroanalysis approach. Data are also presented on the sensitivity of electrodeposited Bi 2Te 3 film composition to the electrodeposition potential. This newly developed method can be used for the compositional analysis of other thermoelectric thin-film material candidates in general.

  6. Dispersive Stabilization of Liquid Crystal-in-Water with Acrylamide Copolymer/Surfactant Mixture: Nematic Curvilinear Aligned Phase Composite Film.

    Science.gov (United States)

    Park; Lee

    1999-11-01

    The effect of nonionic surfactant, (H(OCH(2)-CH(2))(8)-OC(6)H(4)-C(9)H(19)), on the dispersion stabilization of liquid crystal (LC)-in-water with acrylamide copolymer containing the related nonylphenyl groups was studied. It was observed that the addition of nonionic surfactant increases the stability of LC dispersions and improves the electrooptical properties of the nematic curvilinear aligned phase (NCAP) composite film. On the basis of the surface tension, reduced viscosity, cloud point, and coalescence time measurements, it was proposed that formation of an integrated structure induced by interactions between hydrophobic groups in the polymer chains is probably important to fabrication of a polymer composite film made of LC and polymer matrix. Copyright 1999 Academic Press.

  7. Crystal structure and composition of BAlN thin films: Effect of boron concentration in the gas flow

    Science.gov (United States)

    Wang, Shuo; Li, Xiaohang; Fischer, Alec M.; Detchprohm, Theeradetch; Dupuis, Russell D.; Ponce, Fernando A.

    2017-10-01

    We have investigated the microstructure of BxAl1-xN films grown by flow-modulated epitaxy at 1010 °C, with B/(B + Al) gas-flow ratios ranging from 0.06 to 0.18. The boron content obtained from X-ray diffraction (XRD) patterns ranges from x = 0.02 to 0.09. On the other hand, boron content deduced from the aluminum signal in the Rutherford backscattering spectra (RBS) ranges from x = 0.06 to 0.16, closely following the gas-flow ratios. Transmission electron microscopy indicates the sole presence of a wurtzite crystal structure in the BAlN films, and a tendency towards columnar growth for B/(B + Al) gas-flow ratios below 0.12. For higher ratios, the BAlN films exhibit a tendency towards twin formation and finer microstructure. Electron energy loss spectroscopy has been used to profile spatial variations in the composition of the films. The RBS data suggest that the incorporation of B is highly efficient for our growth method, while the XRD data indicate that the epitaxial growth may be limited by a solubility limit in the crystal phase at about 9%, for the range of B/(B + Al) gas-flow ratios that we have studied, which is significantly higher than previously thought.

  8. Crystal structure and composition of BAlN thin films: Effect of boron concentration in the gas flow

    KAUST Repository

    Wang, Shuo

    2017-07-20

    We have investigated the microstructure of BxAl1-xN films grown by flow-modulated epitaxy at 1010 oC, with B/(B+Al) gas-flow ratios ranging from 0.06 to 0.18. The boron content obtained from X-ray diffraction (XRD) patterns ranges from x = 0.02 to 0.09. On the other hand, boron content deduced from the aluminum signal in the Rutherford backscattering spectra (RBS) ranges x = 0.06 to 0.16, closely following gas-flow ratios. Transmission electron microscopy indicates the sole presence of wurtzite crystal structure in the BAlN films, and a tendency towards columnar growth for B/(B+Al) gas-flow ratios below 0.12. For higher ratios, the BAlN films exhibit a tendency towards twin formation and finer microstructure. Electron energy loss spectroscopy has been used to profile spatial variations in the composition of the films.The RBS data suggest that the incorporation of B is highly efficient for our growth method, while the XRD data indicate that the epitaxial growth may be limited by a solubility limit in the crystal phase at about 9%, for the range of B/(B+Al) gas-flow ratios that we used, which is significantly higher than previously thought.

  9. Fabrication and characterization of novel composite membranes composed of photonic crystals and TiO2 nanotube array films

    Science.gov (United States)

    Tang, Junjie; Zhu, Huili; Wang, Aijun; Chen, Sheng-Li; Yuan, Yao

    2016-05-01

    Novel composite membranes composed of photonic crystals (PCs) and TiO2 nanotube array (TNA) films have been fabricated by combining the room temperature floating self-assembly (RTFSA) method, recently developed by our research group, and the liquid-phase deposition technique. By applying this combined procedure, polystyrene (PS) opal PC/TNA and TiO2 inverse opal PC/TNA composite membranes were prepared. Scanning electron microscopy and ultraviolet/visible spectroscopy analyses showed that the membrane samples possessed very high crystalline quality. Notably, the ordered packing of the PS microspheres from the top to the bottom of the opal PC film was not affected by the surface roughness of the porous TNA substrate. This is attributed to the self-assembly mechanism of the colloidal particles, which produces a three-dimensional ordered structure in the RTFSA method. Herein, the crystallization of the colloidal particles occurred at the surface of the colloidal suspension, and the crystal growth proceeded downward from the surface of the suspension to the substrate.

  10. Effects of Saponification Rate on Electrooptical Properties and Morphology of Poly(vinyl alcohol)/Liquid Crystal Composite Films

    Science.gov (United States)

    Ono, Hiroshi; Kawatsuki, Nobuhiro

    1995-03-01

    The relationship between the saponification rate of poly(vinyl alcohol) (PVA), and the electrooptical properties and morphology of the PVA/liquid crystal (LC) composite films was investigated. Light transmission clazing and the LC droplet size were varied by changing the saponification rate or the blend ratio of two kinds of PVA with different saponification rates because the refractive index and surface tension could be controlled by the saponification rate of PVA. The threshold voltage decreased with increasing saponification rate though the extrapolation length was decreased. It was suggested that the electrooptical properties were strongly dependent on the droplet size.

  11. Optical sensor platform based on cellulose nanocrystals (CNC) - 4'-(hexyloxy)-4-biphenylcarbonitrile (HOBC) bi-phase nematic liquid crystal composite films.

    Science.gov (United States)

    Santos, Moliria V; Tercjak, Agnieszka; Gutierrez, Junkal; Barud, Hernane S; Napoli, Mariana; Nalin, Marcelo; Ribeiro, Sidney J L

    2017-07-15

    The preparation of composite materials has gained tremendous attention due to the potential synergy of the combined materials. Here we fabricate novel thermal/electrical responsive photonic composite films combining cellulose nanocrystals (CNC) with a low molecular weight nematic liquid crystal (NLC), 4'-(hexyloxy)-4-biphenylcarbonitrile (HOBC). The obtained composite material combines both intense structural coloration of photonic cellulose and thermal and conductive properties of NLC. Scanning electron microscopy (SEM) results confirmed that liquid crystals coated CNC films maintain chiral nematic structure characteristic of CNC film and simultaneously, transversal cross-section scanning electron microscopy images indicated penetration of liquid crystals through the CNC layers. Investigated composite film maintain NLC optical properties being switchable as a function of temperature during heating/cooling cycles. The relationship between the morphology and thermoresponsive in the micro/nanostructured materials was investigated by using transmission optical microscopy (TOM). Conductive response of the composite films was proved by Electrostatic force microscopy (EFM) measurement. Designed thermo- and electro-responsive materials open novel simple pathway of fabrication of CNC-based materials with tunable properties. Copyright © 2017. Published by Elsevier Ltd.

  12. A biosensor of high-density lipoprotein of human serum on a liquid crystal and polymer composite film

    Science.gov (United States)

    Lin, Yi-Hsin; Chang, Kai-Han; Chu, Wei-Lin; Tsou, Yu-Shih; Wu, Li-Ching; Li, Chien-Feng

    2013-10-01

    A biosensor for the concentration of high-density lipoprotein (HDL) in human serum on a liquid crystal and polymer composite film (LCPCF) is demonstrated. The sensing mechanism is based on a polar-polar interaction between orientation of LC directors and HDL in human serum. The concentration of polar HDL in human serum affects the orientations of LC directors at the interface between LCPCF and the human serum. In addition, the surface free energy of LCPCF changes with the applied voltage due to the electrically tunable orientations of LC directors anchored among the polymer grains of LCPCF. As a result, the droplet motion of human serum on LCPCF under applied voltages can sense the concentration of HDL in human serum.

  13. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  14. Correlation of annealing time with crystal structure, composition, and electronic properties of CH3NH3PbI3-xClx mixed-halide perovskite films.

    Science.gov (United States)

    Ralaiarisoa, Maryline; Busby, Yan; Frisch, Johannes; Salzmann, Ingo; Pireaux, Jean-Jacques; Koch, Norbert

    2016-12-21

    Using 3D imaging with time-of-flight secondary ion mass spectrometry (ToF-SIMS) complemented by grazing-incidence X-ray diffraction (GIXRD), we spatially resolve changes in both the composition and structure of CH3NH3I3-xClx perovskite films on conducting polymer substrates at different annealing stages, in particular, before and after complete perovskite crystallization. The early stage of annealing is characterized by phase separation throughout the entire film into domains with perovskite and domains with a dominating chloride-rich phase. After sufficiently long annealing, one single perovskite phase of homogeneous composition on the (lateral) micrometer scale is observed, along with pronounced film texture. This composition evolution is accompanied by diffusion of chloride from the perovskite layer towards the conducting polymer substrate, and even accumulation there. Photoelectron spectroscopy analysis further shows that perovskite films become increasingly n-type with annealing time and upon full conversion, which correlates with the change of film composition. Our results accentuate the importance of chloride for the formation of crystalline and textured films, which are crucial for enhancing the PV performance of perovskite-based solar cells.

  15. Polymer film composite transducer

    Science.gov (United States)

    Owen, Thomas E.

    2005-09-20

    A composite piezoelectric transducer, whose piezoeletric element is a "ribbon wound" film of piezolectric material. As the film is excited, it expands and contracts, which results in expansion and contraction of the diameter of the entire ribbon winding. This is accompanied by expansion and contraction of the thickness of the ribbon winding, such that the sound radiating plate may be placed on the side of the winding.

  16. The Transmission Modes and Losses of the Poled Nano-crystal and Polymer Composite PbTiO3/PEK-c Thin-film Waveguides

    Institute of Scientific and Technical Information of China (English)

    REN Quan; Yuk Tak Chow; YANG Xudong; LV Zenghai; YANG Hongliang; CHAN Hau Ping; CHU Pak Lim

    2007-01-01

    Composite thin films of PbTiO3 nano-crystals and high transparency polymer polyetherketone(PEK-c) for application of non-linear optical devices were prepared by spin coating. The size of PbTiO3 nano-crystals was estimated to be 30-40 nm using a transmission electron microscope. The refractive index and the mode propagation losses at 633 nm were measured using the prism coupling technique and improved photographic technique respectively. They were found to be 1.6545 and 2.00 dB cm-1 (fundamental mode),respectively. Moreover, it is observed that this loss is increased at higher mode indices.

  17. Chitosan-Assisted Crystallization and Film Forming of Perovskite Crystals through Biomineralization.

    Science.gov (United States)

    Yang, Yang; Sun, Chen; Yip, Hin-Lap; Sun, Runcang; Wang, Xiaohui

    2016-03-18

    Biomimetic mineralization is a powerful approach for the synthesis of advanced composite materials with hierarchical organization and controlled structure. Herein, chitosan was introduced into a perovskite precursor solution as a biopolymer additive to control the crystallization and to improve the morphology and film-forming properties of a perovskite film by way of biomineralization. The biopolymer additive was able to control the size and morphology of the perovskite crystals and helped to form smooth films. The mechanism of chitosan-mediated nucleation and growth of the perovskite crystals was explored. As a possible application, the chitosan-perovskite composite film was introduced into a planar heterojunction solar cell and increased power conversion efficiency relative to that observed for the pristine perovskite film was achieved. The biomimetic mineralization method proposed in this study provides an alternative way of preparing perovskite crystals with well-controlled morphology and properties and extends the applications of perovskite crystals in photoelectronic fields, including planar-heterojunction solar cells.

  18. Crystallization kinetics of amorphous aluminum-tungsten thin films

    Energy Technology Data Exchange (ETDEWEB)

    Car, T.; Radic, N. [Rugjer Boskovic Inst., Zagreb (Croatia). Div. of Mater. Sci.; Ivkov, J. [Institute of Physics, Bijenicka 46, P.O.B. 304, HR-10000 Zagreb (Croatia); Babic, E.; Tonejc, A. [Faculty of Sciences, Physics Department, Bijenicka 32, P.O.B. 162, HR-10000 Zagreb (Croatia)

    1999-01-01

    Crystallization kinetics of the amorphous Al-W thin films under non-isothermal conditions was examined by continuous in situ electrical resistance measurements in vacuum. The estimated crystallization temperature of amorphous films in the composition series of the Al{sub 82}W{sub 18} to Al{sub 62}W{sub 38} compounds ranged from 800 K to 920 K. The activation energy for the crystallization and the Avrami exponent were determined. The results indicated that the crystallization mechanism in films with higher tungsten content was a diffusion-controlled process, whereas in films with the composition similar to the stoichiometric compound (Al{sub 4}W), the interface-controlled crystallization probably occurred. (orig.) With 4 figs., 1 tab., 26 refs.

  19. On dewetting of thin films due to crystallization (crystallization dewetting).

    Science.gov (United States)

    Habibi, Mehran; Rahimzadeh, Amin; Eslamian, Morteza

    2016-03-01

    Drying and crystallization of a thin liquid film of an ionic or a similar solution can cause dewetting in the resulting thin solid film. This paper aims at investigating this type of dewetting, herein termed "crystallization dewetting", using PbI2 dissolved in organic solvents as the model solution. PbI2 solid films are usually used in X-ray detection and lead halide perovskite solar cells. In this work, PbI2 films are fabricated using spin coating and the effect of major parameters influencing the crystallization dewetting, including the type of the solvent, solution concentration, drying temperature, spin speed, as well as imposed vibration on the substrate are studied on dewetting, surface profile and coverage, using confocal scanning laser microscopy. Simplified hydrodynamic governing equations of crystallization in thin films are presented and using a mathematical representation of the process, it is phenomenologically demonstrated that crystallization dewetting occurs due to the absorption and consumption of the solution surrounding a growing crystal. Among the results, it is found that a low spin speed (high thickness), a high solution concentration and a low drying temperature promote crystal growth, and therefore crystallization dewetting. It is also shown that imposed vibration on the substrate can affect the crystal size and crystallization dewetting.

  20. Thermal Expansion Coefficients of Thin Crystal Films

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The formulas for atomic displacements and Hamiltonian of a thin crystal film in phonon occupation number representation are obtained with the aid of Green's function theory. On the basis of these results, the formulas for thermal expansion coefficients of the thin crystal film are derived with the perturbation theory, and the numerical calculations are carried out. The results show that the thinner films have larger thermal expansion coefficients.

  1. Composition and crystal structure of N doped TiO2 film deposited at different O2 flow rate by direct current sputtering.

    Science.gov (United States)

    Ding, Wanyu; Ju, Dongying; Chai, Weiping

    2011-06-01

    N doped Ti02 films were deposited by direct current pulse magnetron sputtering system at room temperature. The influence of 02 flow rate on the crystal structure of deposited films was studied by Stylus profilometer, X-ray photoelectron spectroscopy, and X-ray diffractometer. The results indicate that the 02 flow rate strongly controls the growth behavior and crystal structure of N doped Ti02 film. It is found that N element mainly exists as substitutional doped state and the chemical stiochiometry is near to TiO1.68±0.06N0.11±0.01 for all film samples. N doped Ti02 film deposited with 2 sccm (standard-state cubic centimeter per minute) 02 flow rate is amorphous structure with high growth rate, which contains both anatase phase and rutile phase crystal nucleuses. In this case, the film displays the mix-phase of anatase and rutile after annealing treatment. While N doped Ti02 film deposited with 12 cm(3)/min 02 flow rate displays anatase phase before and after annealing treatment. And it should be noticed that no TiN phase appears for all samples before and after annealing treatment.

  2. Crystallization of zirconia based thin films.

    Science.gov (United States)

    Stender, D; Frison, R; Conder, K; Rupp, J L M; Scherrer, B; Martynczuk, J M; Gauckler, L J; Schneider, C W; Lippert, T; Wokaun, A

    2015-07-28

    The crystallization kinetics of amorphous 3 and 8 mol% yttria stabilized zirconia (3YSZ and 8YSZ) thin films grown by pulsed laser deposition (PLD), spray pyrolysis and dc-magnetron sputtering are explored. The deposited films were heat treated up to 1000 °C ex situ and in situ in an X-ray diffractometer. A minimum temperature of 275 °C was determined at which as-deposited amorphous PLD grown 3YSZ films fully crystallize within five hours. Above 325 °C these films transform nearly instantaneously with a high degree of micro-strain when crystallized below 500 °C. In these films the t'' phase crystallizes which transforms at T > 600 °C to the t' phase upon relaxation of the micro-strain. Furthermore, the crystallization of 8YSZ thin films grown by PLD, spray pyrolysis and dc-sputtering are characterized by in situ XRD measurements. At a constant heating rate of 2.4 K min(-1) crystallization is accomplished after reaching 800 °C, while PLD grown thin films were completely crystallized already at ca. 300 °C.

  3. Improved piezoelectricity of PVDF-HFP/carbon black composite films

    Science.gov (United States)

    Wu, Liangke; Yuan, Weifeng; Hu, Ning; Wang, Zhongchang; Chen, Chunlin; Qiu, Jianhui; Ying, Ji; Li, Yuan

    2014-04-01

    We report a substantial improvement of piezoelectricity for poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) copolymer films by introducing carbon black (CB) into the PVDF-HFP to form PVDF-HFP/CB composite films. The optimized output voltage of the composite film at an optimal CB content of 0.5 wt% is found to be 204% of the pristine PVDF-HFP film. Its harvested electrical power density is 464% and 561% of the pristine PVDF-HFP film by using ac and dc circuits, respectively. Through Fourier transform infrared spectroscopy analysis, differential scanning calorimetry analysis, and polarized optical microscopy observations, we clarify the enhancement mechanism of piezoelectricity for the PVDF-HFP/CB composite films. We find that the added CB acts as nucleating agent during the initial formation of crystals, but imposes an insignificant effect on the α-β phase transformation during stretching. We also demonstrate that the addition of optimal CB reduces crystal size yet increases the number of crystals in the composite films. This is beneficial for the formation of elongated, oriented and fibrillar crystalline morphology during stretching and consequently results in a highly efficient poling process. The addition of overdosed CB leads to the formation of undersized crystals, lowered crystallinity, and hence reduced piezoelectric performance of the PVDF-HFP/CB composite films.

  4. A composite hydrogels-based photonic crystal multi-sensor

    Science.gov (United States)

    Chen, Cheng; Zhu, Zhigang; Zhu, Xiangrong; Yu, Wei; Liu, Mingju; Ge, Qiaoqiao; Shih, Wei-Heng

    2015-04-01

    A facile route to prepare stimuli-sensitive poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) gelated crystalline colloidal array photonic crystal material was developed. PVA was physically gelated by utilizing an ethanol-assisted method, the resulting hydrogel/crystal composite film was then functionalized with PAA to form an interpenetrating hydrogel film. This sensor film is able to efficiently diffract the visible light and rapidly respond to various environmental stimuli such as solvent, pH and strain, and the accompanying structural color shift can be repeatedly changed and easily distinguished by naked eye.

  5. Influence of the elemental composition and crystal structure on the vacuum properties of Ti-Zr-V non-evaporable getter films

    CERN Document Server

    Prodromides, A E; Chiggiato, P; Mongelluzzo, A; Ruzinov, V; Scheuerlein, C; Taborelli, M; Lévy, F

    2001-01-01

    Non-evaporable thin film getters based on the elements of the 4th and 5th columns of the periodic table have been deposited by sputtering. Among the about 20 alloys studied to date, the lowest activation temperature (about 180 °C for a 24-hour heating) has been found for the Ti-Zr-V system in a well-defined composition range. The characterization of the activation behavior of such Ti-Zr-V films is presented. The evolution of the surface chemical composition during activation is monitored by Auger Electron Spectroscopy (AES) and the functional properties are evaluated by pumping speed measurements. The pumping speed characteristics are quite similar to those already measured for commercially available NEG materials, except for the much lower saturation coverage for CO. This inconvenience, which is due to the smooth surface structure of these films, can be counteracted by increasing the roughness of the substrate.

  6. Composition dependences of crystal structure and electrical properties of epitaxial Pb(Zr,Ti)O3 films grown on Si and SrTiO3 substrates

    Science.gov (United States)

    Okamoto, Shoji; Okamoto, Satoshi; Yokoyama, Shintaro; Akiyama, Kensuke; Funakubo, Hiroshi

    2016-10-01

    {100}-oriented Pb(Zr x ,Ti1- x )O3 (PZT) thin films of approximately 2 µm thickness and Zr/(Zr + Ti) ratios of 0.39-0.65 were epitaxially grown on (100)cSrRuO3//(100)SrTiO3 (STO) and (100)cSrRuO3//(100)cLaNiO3//(100)CeO2//(100)YSZ//(100)Si (Si) substrates having different thermal expansion coefficients by pulsed metal-organic chemical vapor deposition (MOCVD). The effects of Zr/(Zr + Ti) ratio and type of substrate on the crystal structure and dielectric, ferroelectric and piezoelectric properties of the films were systematically investigated. The X-ray diffraction measurement showed that both films changed from having a tetragonal symmetry to rhombohedral symmetry through the coexisting region with increasing Zr/(Zr + Ti) ratio. This region showed the Zr/(Zr + Ti) ratios of 0.45-0.59 for the films on the STO substrates that were wider than the films on the Si substrates. Saturation polarization values were minimum at approximately Zr/(Zr + Ti) = 0.50 for the films on the STO substrates, and no obvious Zr/(Zr + Ti) ratio dependence was detected in the films on the Si substrates. On the other hand, the maximum field-induced strain values measured by scanning force microscopy at approximately Zr/(Zr + Ti) = 0.50 at 100 kV/cm were about 0.5 and 0.1% in the films on the Si and STO, respectively.

  7. Heat Flux Through Slag Film and Its Crystallization Behavior

    Institute of Scientific and Technical Information of China (English)

    TANG Ping; XU Chu-shao; WEN Guang-hua; ZHAO Yan-hong; QI Xin

    2008-01-01

    An experimental apparatus for simulating copper mold is used to quantify the heat flux through the slag film and to obtain a solid slag for further determining its crystallization behavior.The result indicates that both the chemical composition of the mold powder and the cooling rate have an important influence on the heat flux through the slag film.With increasing the binary hasicity,the heat flux of slag film decreases at first,reaches the minimum at the basicity of 1.4,and then increases,indicating that the maximum binary basicity is about 1.4 for selecting"mild cooling"mold powder.The heat transfer through the slag film can be specified in terms of the crystalline ratio and the thickness of the slag film.Reerystallization of the solid slag occurs and must be considered as an important factor that may influence the heat transfer through the solid slag layer.

  8. Domains in Ferroic Crystals and Thin Films

    CERN Document Server

    Tagantsev, Alexander K; Fousek, Jan

    2010-01-01

    Domains in Ferroic Crystals and Thin Films presents experimental findings and theoretical understanding of ferroic (non-magnetic) domains developed during the past 60 years. It addresses the situation by looking specifically at bulk crystals and thin films, with a particular focus on recently-developed microelectronic applications and methods for observation of domains with techniques such as scanning force microscopy, polarized light microscopy, scanning optical microscopy, electron microscopy, and surface decorating techniques. Domains in Ferroic Crystals and Thin Films covers a large area of material properties and effects connected with static and dynamic properties of domains, which are extremely relevant to materials referred to as ferroics. In most solid state physics books, one large group of ferroics is customarily covered: those in which magnetic properties play a dominant role. Numerous books are specifically devoted to magnetic ferroics and cover a wide spectrum of magnetic domain phenomena. In co...

  9. Crystallization and Transport Properties of Amorphous Cr-Si Thin Film Thermoelectrics

    Science.gov (United States)

    Novikov, S. V.; Burkov, A. T.; Schumann, J.

    2014-06-01

    We studied the thermoelectric properties, crystallization, and stability of amorphous and nanocrystalline states in Cr-Si composite films. Amorphous films, prepared by magnetron sputtering, were transformed into the nanocrystalline state by annealing with in situ thermopower and electrical resistivity measurements. We have found that the amorphous state is stable in these film composites to about 550 K. Prior to crystallization, the amorphous films undergo a structural relaxation, detected by peculiarities in the temperature dependences of the transport properties, but not visible in x-ray or electron diffraction. The magnitude and temperature dependences of electrical conductivity and thermopower indicate that electron transport in the amorphous films is through extended states. The amorphous films are crystallized at annealing temperatures above 550 K into a nanocrystalline composite with an average grain size of 10-20 nm.

  10. Topological Defects in Liquid Crystal Films

    Institute of Scientific and Technical Information of China (English)

    DUAN Yi-Shi; ZHAO Li; ZHANG Xin-Hui; SI Tie-Yan

    2007-01-01

    A topological theory of liquid crystal films in the presence of defects is developed based on the φ-mapping topological current theory. By generalizing the free-energy density in "one-constant" approximation, a covariant freeenergy density is obtained, from which the U(1) gauge field and the unified topological current for monopoles and strings in liquid crystals are derived. The inner topological structure of these topological defects is characterized by the winding numbers of φ-mapping.

  11. On the crystallization of amorphous germanium films

    Science.gov (United States)

    Edelman, F.; Komem, Y.; Bendayan, M.; Beserman, R.

    1993-06-01

    The incubation time for crystallization of amorphous Ge (a-Ge) films, deposited by e-gun, was studied as a function of temperature between 150 and 500°C by means of both in situ transmission electron microscopy and Raman scattering spectroscopy. The temperature dependence of t0 follows an Arrhenius curve with an activation energy of 2.0 eV for free-sustained a-Ge films. In the case where the a-Ge films were on Si 3N 4 substrate, the activation energy of the incubation process was 1.3 eV.

  12. Inkjet printing of single-crystal films

    Science.gov (United States)

    Minemawari, Hiromi; Yamada, Toshikazu; Matsui, Hiroyuki; Tsutsumi, Jun'ya; Haas, Simon; Chiba, Ryosuke; Kumai, Reiji; Hasegawa, Tatsuo

    2011-07-01

    The use of single crystals has been fundamental to the development of semiconductor microelectronics and solid-state science. Whether based on inorganic or organic materials, the devices that show the highest performance rely on single-crystal interfaces, with their nearly perfect translational symmetry and exceptionally high chemical purity. Attention has recently been focused on developing simple ways of producing electronic devices by means of printing technologies. `Printed electronics' is being explored for the manufacture of large-area and flexible electronic devices by the patterned application of functional inks containing soluble or dispersed semiconducting materials. However, because of the strong self-organizing tendency of the deposited materials, the production of semiconducting thin films of high crystallinity (indispensable for realizing high carrier mobility) may be incompatible with conventional printing processes. Here we develop a method that combines the technique of antisolvent crystallization with inkjet printing to produce organic semiconducting thin films of high crystallinity. Specifically, we show that mixing fine droplets of an antisolvent and a solution of an active semiconducting component within a confined area on an amorphous substrate can trigger the controlled formation of exceptionally uniform single-crystal or polycrystalline thin films that grow at the liquid-air interfaces. Using this approach, we have printed single crystals of the organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) (ref. 15), yielding thin-film transistors with average carrier mobilities as high as 16.4cm2V-1s-1. This printing technique constitutes a major step towards the use of high-performance single-crystal semiconductor devices for large-area and flexible electronics applications.

  13. Alignment mechanism of liquid crystal in a stretched porous polymer film

    Science.gov (United States)

    Fujikake, Hideo; Kuboki, Masashi; Murashige, Takeshi; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro

    2003-09-01

    This article discusses the mechanism of nematic liquid crystal alignment in stretched porous polymer films. The polymer films were formed by extreme stretching of an isotropic porous polyolefin, such that the draw ratio was 12:1. A 6-μm-thick porous film with a high porosity coefficient of 92% revealed fine string-shaped areas that exhibited optical anisotropy due to their possessing a high degree of molecular alignment. The porous film was filled with nematic liquid crystal and then the composite film was sandwiched between transparent electrodes coated onto glass substrates, without the use of conventional alignment layers. From polarizing microscopy observations it was found that the string-like polymer areas induce liquid crystal molecular alignment. The liquid crystal cells can exhibit an electrically controlled birefringence effect. This alignment technique enables us to realize three-dimensional control of liquid crystal alignment.

  14. Crystal structure of fiber structured pentacene thin films

    OpenAIRE

    2007-01-01

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

  15. Coassembly of gold nanoparticles and cellulose nanocrystals in composite films.

    Science.gov (United States)

    Lukach, Ariella; Thérien-Aubin, Héloïse; Querejeta-Fernández, Ana; Pitch, Natalie; Chauve, Grégory; Méthot, Myriam; Bouchard, Jean; Kumacheva, Eugenia

    2015-05-12

    Coassembly of nanoparticles with different size-, shape-, and composition-dependent properties is a promising approach to the design and fabrication of functional materials and devices. This paper reports the results of a detailed investigation of the formation and properties of free-stranding composite films formed by the coassembly of cellulose nanocrystals and shape-isotropic plasmonic gold nanoparticles. The effect of gold nanoparticle size, surface charge, and concentration on the structural and optical properties of the composite films has been studied. The composite films retained photonic crystal and chiroptical activity properties. The size and surface charge of gold nanoparticles had a minor effect on the structure and properties of the composite films, while the concentration of gold nanoparticles in the composite material played a more significant role and can be used to fine-tune the optical properties of materials derived from cellulose nanocrystals. These findings significantly broaden the range of nanoparticles that can be used for producing nanocomposite materials based on cellulose nanocrystals. The simplicity of film preparation, the abundance of cellulose nanocrystals, and the robust, free-standing nature of the composite films offer highly advantageous features and pave the way for the generation of functional materials with coupled optical properties.

  16. Starch composites reinforced by bamboo cellulosic crystals.

    Science.gov (United States)

    Liu, Dagang; Zhong, Tuhua; Chang, Peter R; Li, Kaifu; Wu, Qinglin

    2010-04-01

    Using a method of combined HNO(3)-KClO(3) treatment and sulfuric acid hydrolysis, bamboo cellulose crystals (BCCs) were prepared and used to reinforce glycerol plasticized starch. The structure and morphology of BCCs were investigated using X-ray diffraction, electron microscopy, and solid-state (13)C NMR. Results showed that BCCs were of typical cellulose I structure, and the morphology was dependent on its concentration in the suspension. BCC of 50-100 nm were assembled into leaf nervations at low concentration (i.e. 0.1 wt.% of solids), but congregated into a micro-sized "flower" geometry at high concentration (i.e. 10.0 wt.% of solids). Tensile strength and Young's modulus of the starch/BCC composite films (SBC) were enhanced by the incorporation of the crystals due to reinforcement of BCCs and reduction of water uptake. BCCs at the optimal 8% loading level exhibited a higher reinforcing efficiency for plasticized starch plastic than any other loading level.

  17. Thin aligned organic polymer films for liquid crystal devices

    CERN Document Server

    Foster, K E

    1997-01-01

    This project was designed to investigate the possibility of producing alignment layers for liquid crystal devices by cross-linking thin films containing anisotropic polymer bound chromophores via irradiation with polarised ultraviolet light. Photocross-linkable polymers find use in microelectronics, liquid crystal displays, printing and UV curable lacquers and inks; so there is an increasing incentive for the development of new varieties of photopolymers in general. The synthesis and characterisation of two new photopolymers that are suitable as potential alignment layers for liquid crystal devices are reported in this thesis. The first polymer contains the anthracene chromophore attached via a spacer unit to a methacrylate backbone and the second used a similarly attached aryl azide group. Copolymers of the new monomers with methyl methacrylate were investigated to establish reactivity ratios in order to understand composition drift during polymerisation.

  18. Compositional Analysis of Electrodeposited Cu-Se Compound Semiconductor Thin Films Using Combined Voltammetry and Flow-Electrochemical Quartz Crystal Microgravimetry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wooju; Jeong, Seonghan; Myung, Noseung [Konkuk Univ., Chungju (Korea, Republic of); Rajeshwar, Krishnan [Univ. of Texas at Arlington, Arlington (United States); Lee, Chiwoo [Korea Univ., Seoul (Korea, Republic of)

    2013-10-15

    A novel method which is species selective for the compositional analysis of electrodeposited Cu-Se semiconductor films was developed using combined voltammetry and flow-EQCM. The amounts of free Se and Se in Cu{sub 2}Se were obtained from the frequency changes at constant potentials of -0.8 V and -3 V, respectively. Potential steps to -0.8 V and -1.3 V were employed to reduce free Se to Se{sub 2}{sup -} and Cu{sub 2}Se to Cu + Se{sub 2}{sup -}, respectively. Resultant total Cu was anodically stripped at +0.8 V and the free Cu content was calculated using the difference in frequency changes observed during the stripping of total Cu and Se in Cu{sub 2}Se. The results showed that the amounts of free Se, free Cu and the targeted Cu{sub 2}Se varied with deposition potential as well as film thickness. The ternary compound semiconductor CuInSe{sub 2} (CIS) has attracted great interest due to its unique properties and wide applications.

  19. Structural Characteristics and Crystallization of Metallic Glass Sputtered Films by Using Zr System Target

    Directory of Open Access Journals (Sweden)

    Katsuyoshi Kondoh

    2008-01-01

    Full Text Available Zr-Al-Ni-Cu thin films were deposited by the radio-frequency sputtering method at low substrate temperature using three kinds of targets: Zr55Al10Ni5Cu30 bulk metallic glass target (α-BMG target, crystallized bulk metallic glass target (c-BMG target, and an elemental composite target composed of each Zr, Al, Ni chips, and Cu plate. XRD profiles of the films prepared when using these targets indicated that all of the films showed amorphous structures. While XRD profiles of the films using α- and c-BMG targets revealed a broad peak of 2θ=38 degree in the same way as the α-BMG target indicating amorphous structures, that of the film using elemental composite targets showed a broad peak of 2θ=42 degree, which is higher compared to the latter material. As a result of annealing the films at various temperatures for 900 seconds, the film using the α-BMG target showed a crystallization temperature of 748 K, higher than that of BMG with 723 K, while the other films had lower crystallization temperatures below 723 K. XRD profiles also indicated that the crystallized compounds of the films were different from those of BMG target.

  20. Perovskite solar cells: Shedding light on film crystallization

    Science.gov (United States)

    Bakr, Osman M.; Mohammed, Omar F.

    2017-06-01

    A study on the formation of methylammonium lead iodide perovskite films reveals that light illumination influences the crystallization kinetics, therefore affecting the final photovoltaic performance of these materials.

  1. Crystallization and thermal properties of Polylactide/Palygorskite composites

    CSIR Research Space (South Africa)

    Kesavan Pillai, Sreejarani

    2014-06-01

    Full Text Available properties, clay John Wiley & Sons, Inc. Journal of Applied Polymer Science For Peer Review 808x381mm (120 x 120 DPI) Page 1 of 34 John Wiley & Sons, Inc. Journal of Applied Polymer Science For Peer Review Table 1 Films Tg/°C Tc/°C ∆Hm.../Paly (2 wt.%) composite. This decrease in Tcc is an indication of faster crystallization of PLA under the influence of Paly nanoparticles. Sabzi et al.40 recently reported similar results on PLA/ sepiolite composites and found that sepiolite...

  2. Semiconductor liquid crystal composition and methods for making the same

    Science.gov (United States)

    Alivisatos, A. Paul; Li, Liang-shi

    2005-04-26

    Semiconductor liquid crystal compositions and methods for making such compositions are disclosed. One embodiment of the invention is directed to a liquid crystal composition including a solvent and semiconductor particles in the solvent. The solvent and the semiconductor particles are in an effective amount in the liquid crystal composition to form a liquid crystal phase.

  3. Kinetics of sucrose crystallization in whey protein films.

    Science.gov (United States)

    Dangaran, Kirsten L; Krochta, John M

    2006-09-20

    The kinetics of sucrose crystallization in whey protein isolate (WPI) films was studied at 25 degrees C in four different relative humidity environments: 23, 33, 44, and 53%. The effects of protein matrix, crystallization inhibitors, and storage environment on the rate constants of sucrose crystallization were determined using the Avrami model of crystallization. It was found that a cross-linked, denatured whey protein (WP) matrix more effectively hindered sucrose crystallization than a protein matrix of native WP. The crystallization inhibitors tested were lactose, raffinose, modified starch (Purity 69), and polyvinylpyrrolidone (Plasdone C15). Raffinose and modified starch were determined to be the more effective inhibitors of sucrose crystallization. At lower relative humidities (23, 33, and 44%), the cross-linked protein matrix played a more important role in sucrose crystallization than the inhibitors. As relative humidity increased (53%), the crystallization inhibitors were more central to controlling sucrose crystallization in WPI films.

  4. The Crystallization Behaviors and Thermal Properties of PVA/NCC Composite Films%聚乙烯醇/纳米纤维素晶体复合膜热学性能

    Institute of Scientific and Technical Information of China (English)

    唐丽荣; 黄彪; 戴达松; 欧文; 李玉华; 陈学榕

    2011-01-01

    以微晶纤维素(MCC)为原料,通过硫酸水解得到纳米纤维素晶体(NCC),再将纳米纤维素晶体与聚乙烯醇复合共混制备聚乙烯醇/纳米纤维素晶体复合膜,研究复合膜的热学性能,同时采用场发射透射电镜(FETEM)、场发射扫描电镜( FE-SEM)、原子力显微镜(AFM)、热重分析(TG)、差示扫描量热仪(DSC)等仪器对纳米纤维素晶体及其复合膜进行表征与分析.结果表明:所制得的纳米纤维素晶体直径约2~24 nm,50~450 nm长,呈棒状;由FE-SEM图可观察到纳米纤维素晶体与聚乙烯醇具有良好的界面相互作用,但在较大添加量7%时,NCC出现部分团聚,与基体的相容性下降;由TG和DSC分析说明NCC与PVA基体可较好相容,形成了热稳定性较好的复合膜,但当NCC添加量较大时,由于团聚使复合膜热稳定性下降.%Nanocellulose crystal( NCC) was prepared from microcrystalline cellulose ( MCC ) by sulfuric acid treatment, and composite films were prepared from polyvinyl alcohol(PVA) as the matrix and NCC as the filler. Their morphology, size and thermal properties were characterized by field emission transmission electron microscopy ( FETEM) , atomic force microscopy ( AFM ) , field emission gun environment scanning electron microscopes ( FEGE-SEM ) , thermogravimetric analysis(TG)and differential scanning calorimetry ( DSC ). The results indicated that the diameter of NCC was about 2 -24 nm, with the length 50 -450 nm. From FE-SEM images, it could be observed that PVA /NCC composite films were created by casting from a water suspension to produce a homogeneous dispersion of NCC in the polymer matrix. But it showed some agglomeration when the filler loading reached to 7% , and the interaction between NCC and PVA decreased. TG and DSC analysis showed excellent interaction between NCC and PVA. The composite films filled with nanocellulose crystal exhibited improved thermal properties as compared to the neat PVA film. On the

  5. Secondary Crystal Growth on a Cracked Hydrotalcite-Based Film Synthesized by the Sol-Gel Method.

    Science.gov (United States)

    Lee, Wooyoung; Lee, Chan Hyun; Lee, Ki Bong

    2016-05-02

    The sol-gel synthesis method is an attractive technology for the fabrication of ceramic films due to its preparation simplicity and ease of varying the metal composition. However, this technique presents some limitations in relation to the film thickness. Notably, when the film thickness exceeds the critical limit, large tensile stresses occur, resulting in a cracked morphology. In this study, a secondary crystal growth method was introduced as a post-treatment process for Mg/Al hydrotalcite-based films synthesized by the sol-gel method, which typically present a cracked morphology. The cracked hydrotalcite-based film was hydrothermally treated for the secondary growth of hydrotalcite crystals. In the resulting film, hydrotalcite grew with a vertical orientation, and the gaps formed during the sol-gel synthesis were filled with hydrotalcite after the crystal growth. The secondary crystal growth method provides a new solution for cracked ceramic films synthesized by the sol-gel method.

  6. Decreased group velocity in compositionally graded films.

    Science.gov (United States)

    Gao, Lei

    2006-03-01

    A theoretical formalism is presented that describes the group velocity of electromagnetic signals in compositionally graded films. The theory is first based on effective medium approximation or the Maxwell-Garnett approximation to obtain the equivalent dielectric function in a z slice. Then the effective dielectric tensor of the graded film is directly determined, and the group velocities for ordinary and extraordinary waves in the film are derived. It is found that the group velocity is sensitively dependent on the graded profile. For a power-law graded profile f(x)=ax(m), increasing m results in the decreased extraordinary group velocity. Such a decreased tendency becomes significant when the incident angle increases. Therefore the group velocity in compositionally graded films can be effectively decreased by our suitable adjustment of the total volume fraction, the graded profile, and the incident angle. As a result, the compositionally graded films may serve as candidate material for realizing small group velocity.

  7. Growth of Hydroxyapatite Crystal in the Presence of Origanic Film

    Institute of Scientific and Technical Information of China (English)

    Yong LIU; Suping HUANG; Xiaohong DAN; Kechao ZHOU

    2004-01-01

    The growth of hydroxyapatite (Hap) crystal in the presence of hexadecylamine was investigated. Due to its high polarity and high charge density, the organic film could increase the ion supersaturation on its surface. Therefore the growth of pure Hap crystals was accelerated. Moreover, the positive headgroups of the organic film could act as recognized nucleation sites and orient the growth of Hap crystals along thedirection.

  8. Novel Microporous Films and Their Composites

    OpenAIRE

    P.C. Wu, Ph.D; Greg Jones, Ph.D; Chris Shelley, Ph.D; Bert Woelfli, Ph.D

    2007-01-01

    Cost-effective microporous films and composites can be made by using polyolefinic material and inorganic fillers. These microporous films and their composites can be designed and manufactured at high speed using commercial equipment for disposable hygiene articles, protective health care garments, building construction and many other industrial applications where air and moisture breathability is needed. The theory, formulations and methods of making these cost-effective polyolefinic-calcium ...

  9. Preparation and Properties of Polyaniline Composite Films

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing-hua

    2002-01-01

    Polyaniline (PAn) was synthesized by chemical oxidation polymerization. The conductive polymer doped by camphor sulfonic acid (CSA) and a matrix polymer,polyamide- 66, polyamide - 1010 or polyamide- 11, were dissolved in m-cresol and the blend solution was cast in a glass and dried for preparing polyaniline composite films.Conductivity was from 10 -6 to 10 0Ω-1·cm-1 with different weight fraction of PAn-CSA. The crystallizttion of the films was studied by means of differential scanning calorimeter (DSC). The treatment of the composite films in different pH value solution would result in decrease of conductivity, especially in an alkaline solution.

  10. Magnetoelectric thin film composites with interdigital electrodes

    Science.gov (United States)

    Piorra, A.; Jahns, R.; Teliban, I.; Gugat, J. L.; Gerken, M.; Knöchel, R.; Quandt, E.

    2013-07-01

    Magnetoelectric (ME) thin film composites on silicon cantilevers are fabricated using Pb(Zr0.52Ti0.45)O3 (PZT) films with interdigital transducer electrodes on the top side and FeCoSiB amorphous magnetostrictive thin films on the backside. These composites without any direct interface between the piezoelectric and magnetostrictive phase are superior to conventional plate capacitor-type thin film ME composites. A limit of detection of 2.6 pT/Hz1/2 at the mechanical resonance is determined which corresponds to an improvement of a factor of approximately 2.8 compared to the best plate type sensor using AlN as the piezoelectric phase and even a factor of approximately 4 for a PZT plate capacitor.

  11. Novel Microporous Films and Their Composites

    Directory of Open Access Journals (Sweden)

    P.C. Wu, Ph.D

    2007-04-01

    Full Text Available Cost-effective microporous films and composites can be made by using polyolefinic material and inorganic fillers. These microporous films and their composites can be designed and manufactured at high speed using commercial equipment for disposable hygiene articles, protective health care garments, building construction and many other industrial applications where air and moisture breathability is needed. The theory, formulations and methods of making these cost-effective polyolefinic-calcium carbonate compositions are discussed. Special engineering fibers and their fabrics can be combined with these novel microporous films to achieve a variety of properties for practical applications. However, one should keep intellectual property considerations in mind when contemplating the manufacture of microporous film products, their companies and their applications.

  12. Crystallization study of amorphous sputtered NiTi bi-layer thin film

    Energy Technology Data Exchange (ETDEWEB)

    Mohri, Maryam, E-mail: mmohri@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany); Nili-Ahmadabadi, Mahmoud [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, University of Tehran, Tehran (Iran, Islamic Republic of); Chakravadhanula, Venkata Sai Kiran [Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany)

    2015-05-15

    The crystallization of Ni-rich/NiTiCu bi-layer thin film deposited by magnetron sputtering from two separate alloy targets was investigated. To achieve the shape memory effect, the NiTi thin films deposited at room temperature with amorphous structure were annealed at 773 K for 15, 30, and 60 min for crystallization. Characterization of the films was carried out by differential scanning calorimetry to indicate the crystallization temperature, grazing incidence X-ray diffraction to identify the phase structures, atomic force microscopy to evaluate surface morphology, scanning transmission electron microscopy to study the cross section of the thin films. The results show that the structure of the annealed thin films strongly depends on the temperature and time of the annealing. Crystalline grains nucleated first at the surface and then grew inward to form columnar grains. Furthermore, the crystallization behavior was markedly affected by composition variations. - Highlights: • A developed bi-layer Ni45TiCu5/Ni50.8Ti was deposited on Si substrate and crystallized. • During crystallization, The Ni{sub 45}TiCu{sub 5} layer is thermally less stable than the Ni-rich layer. • The activation energy is 302 and 464 kJ/mol for Cu-rich and Ni-rich layer in bi-layer, respectively.

  13. Single-crystal semiconductor films grown on foreign substrates

    Science.gov (United States)

    Vohl, P.

    1966-01-01

    Intermediate alloy formed between foreign substrates and semiconductor material enable the growth of single crystal semiconductor films on the alloy layer. The melted film must not ball up on the surface of the substrate and neither chemically react nor alloy with the intermediate alloy formed on the substrate.

  14. Fabrication and Characterization of Colloidal Crystal Thin Films

    Science.gov (United States)

    Rodriguez, I.; Ramiro-Manzano, F.; Meseguer, F.; Bonet, E.

    2011-01-01

    We present a laboratory experiment that allows undergraduate or graduate students to get introduced to colloidal crystal research concepts in an interesting way. Moreover, such experiments and studies can also be useful in the field of crystallography or solid-state physics. The work concerns the growth of colloidal crystal thin films obtained…

  15. Fabrication and Characterization of Colloidal Crystal Thin Films

    Science.gov (United States)

    Rodriguez, I.; Ramiro-Manzano, F.; Meseguer, F.; Bonet, E.

    2011-01-01

    We present a laboratory experiment that allows undergraduate or graduate students to get introduced to colloidal crystal research concepts in an interesting way. Moreover, such experiments and studies can also be useful in the field of crystallography or solid-state physics. The work concerns the growth of colloidal crystal thin films obtained…

  16. Energy distribution of metal and noble gas ions traversing single-crystal copper films

    Science.gov (United States)

    Isakhanov, Z. A.

    2012-09-01

    A comparative investigation of the energy distribution of ions that traversed single-crystal cooper films reveals that the energy loss of channeled and nonchanneled particles depends not only on the mass but also on the radius of bombarding ions. It is established that the energy spectra of transmitted ions are highly sensitive to a change in the composition and structure of the films. From the change in these spectra, one can estimate the degree of disordering in thin films under various applied forces.

  17. Liquid crystal film development for plasma mirrors and waveplates

    Science.gov (United States)

    Cochran, G. E.; Poole, P. L.; Willis, C.; Hanna, R. J.; Pytel, K.; Sullivan, K. S.; Andereck, C. D.; Schumacher, D. W.

    2015-11-01

    Many laser-plasma phenomena currently under study depend critically on the quality of the pulse contrast. Costly sacrificial plasma mirrors are now commonly used to improve the temporal laser contrast before target interaction, especially for ion acceleration where high contrast is necessary to achieve interesting new mechanisms. Liquid crystal films were originally developed as variable thickness thin-film targets, and were demonstrated for this purpose in. Varying film formation parameters such as volume, temperature, and draw speed allows thickness control between 10 nm and several 10s of microns, in-situ and under vacuum. Development since that initial work has allowed large area films to be formed, several cm2 in extent, with the same thickness range. The molecular flatness of a freely suspended film renders these films excellent low-cost plasma mirrors, given appropriate formation control. Additionally, the birefringence of the liquid crystal used here permits these films to be used as large area zero-order waveplates at the appropriate thickness. Details on the current state of liquid crystal film application development, including a >1 Hz small area film formation device, will be presented. This work was performed with support from the DARPA PULSE program through a grant from AMRDEC and by the NNSA under contract DE-NA0001976.

  18. Surface and bulk crystallization of amorphous solid water films: Confirmation of "top-down" crystallization

    Science.gov (United States)

    Yuan, Chunqing; Smith, R. Scott; Kay, Bruce D.

    2016-10-01

    The crystallization kinetics of nanoscale amorphous solid water (ASW) films are investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). TPD measurements are used to probe surface crystallization and RAIRS measurements are used to probe bulk crystallization. Isothermal TPD results show that surface crystallization is independent of the film thickness (from 100 to 1000 ML). Conversely, the RAIRS measurements show that the bulk crystallization time increases linearly with increasing film thickness. These results suggest that nucleation and crystallization begin at the ASW/vacuum interface and then the crystallization growth front propagates linearly into the bulk. This mechanism was confirmed by selective placement of an isotopic layer (5% D2O in H2O) at various positions in an ASW (H2O) film. In this case, the closer the isotopic layer was to the vacuum interface, the earlier the isotopic layer crystallized. These experiments provide direct evidence to confirm that ASW crystallization in vacuum proceeds by a "top-down" crystallization mechanism.

  19. Surface and bulk crystallization of amorphous solid water films: Confirmation of “top-down” crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Chunqing; Smith, R. Scott; Kay, Bruce D.

    2016-10-01

    The crystallization kinetics of nanoscale amorphous solid water (ASW) films are investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). TPD measurements are used to probe surface crystallization and RAIRS measurements are used to probe bulk crystallization. Isothermal TPD results show that surface crystallization is independent of the film thickness (from 100 to 1000 ML). Conversely, the RAIRS measurements show that the bulk crystallization time increases linearly with increasing film thickness. These results suggest that nucleation and crystallization begin at the ASW/vacuum interface and then the crystallization growth front propagates linearly into the bulk. This mechanism was confirmed by selective placement of an isotopic layer (5% D2O in H2O) at various positions in an ASW (H2O) film. In this case, the closer the isotopic layer was to the vacuum interface, the earlier the isotopic layer crystallized. These experiments provide direct evidence to confirm that ASW crystallization in vacuum proceeds by a “top-down” crystallization mechanism.

  20. Crystallization of amorphous Co-Nb-Zr sputtered films

    Energy Technology Data Exchange (ETDEWEB)

    Battezzati, L.; Baricco, M.; Attina, P.

    1986-08-01

    Thermal analysis results obtained with some sputtered Co-Nb-Zr alloys are presented. Microstructural determinations at some stages of the crystallization process were made with transmission electron microscopy and the results given. Crystallization occurs over a wider temperature range than for binary Co/sub 90/Zr/sub 10/ ribbons. Binary Co-Nb films crystallize in the range 750-800K, some 10 degrees below ternary films. The presence of zirconium enhances the stability of the amorphous phase. An explanation of the results is given.

  1. Studies on confined crystallization behavior of polycaprolactone thin films

    Institute of Scientific and Technical Information of China (English)

    QIAO Congde; JIANG Shichun; JI Xiangling; AN Lijia; JIANG Bingzheng

    2007-01-01

    The confined crystallization behavior ofpolycap-rolactone (PCL) in thin and ultrathin films was studied by AFM (atomic force microscopy). It was found that the crys-talline morphology of PCL depended on the film's thickness.When the thickness is d>2Rg (radius of gyration), the polymer can crystallize into spherulites; when Rg < d< 2 Rg,a dense-branch morphology and dendrites could be found;when dcrystallization temperature and the substrate and the molecular weigbt on the crystalline mor-phology were discussed. It was shown that the crystallization of PCL in thin films is a diffusion-controlled process, and it can be explained by diffusion-limited aggregation.

  2. Analysis of thin-film photonic crystal microstructures

    CERN Document Server

    Pottage, J M

    2003-01-01

    Optical-scale microstructures containing thin-film photonic crystals (TFPCs) are modelled by transfer/scattering matrix methods, based on Fourier-series expansion of the optical Bloch eigenmodes. The majority of the TFPCs considered consist of 2D arrays of holes arranged in a triangular lattice, etched into high-index Al sub x Ga sub 1 sub - sub x As and placed on a low-index oxidised substrate. These TFPCs can be easily fabricated by standard electron-beam lithography techniques. Unlike most photonic crystal devices that have been proposed, our 'intra-pass-band' TFPCs would work by exploiting the somewhat surprising properties of propagating optical Bloch waves rather than directly relying on photonic bandgaps. By numerical modelling, it is demonstrated that 2D-patterned TFPCs can support highly dispersive high-Q quasi-guided and truly-guided resonant modes, and the unusual properties of these modes are explained in terms of their Bloch-wave compositions. Modal dispersion diagrams of TFPCs, showing the loci ...

  3. In-plane orientation and composition dependences of crystal structure and electrical properties of {100}-oriented Pb(Zr,Ti)O3 films grown on (100) Si substrates by metal organic chemical vapor deposition

    Science.gov (United States)

    Okamoto, Shoji; Sankara Rama Krishnan, P. S.; Okamoto, Satoshi; Yokoyama, Shintaro; Akiyama, Kensuke; Funakubo, Hiroshi

    2017-10-01

    In-plane orientation-controlled Pb(Zr x ,Ti1‑ x )O3 (PZT) films with a thickness of approximately 2 µm and a Zr/(Zr + Ti) ratio of 0.39–0.65 were grown on (100) Si substrates by pulsed metal–organic chemical vapor deposition (MOCVD). In-plane-oriented epitaxial PZT films and in-plane random fiber-textured PZT films with {100} out-of-plane orientation were grown on (100)c SrRuO3//(100)c LaNiO3//(100) CeO2//(100) YSZ//(100) Si and (100)c SrRuO3/(100)c LaNiO3/(111) Pt/TiO2/SiO2/(100) Si substrates, respectively. The effects of Zr/(Zr + Ti) ratio and in-plane orientation on the crystal structure, dielectric, ferroelectric, and piezoelectric properties of the films were systematically investigated. The X-ray diffraction measurement showed that the epitaxial PZT films had a higher volume fraction of (100) orientation than the fiber-textured PZT films in the tetragonal Zr/(Zr + Ti) ratio region. A large difference was not detected between the epitaxial films and the fiber-textured films for Zr/(Zr + Ti) ratio dependence of the dielectric constant, and remanent polarization. However, in the rhombohedral phase region [Zr/(Zr + Ti) = 0.65], coercive field was found to be 1.5-fold different between the epitaxial and fiber-textured PZT films. The maximum field-induced strains measured at 0–100 kV/cm by scanning atomic force microscopy were obtained at approximately Zr/(Zr + Ti) = 0.50 and were about 0.5 and 0.3% for the epitaxial and fiber-textured PZT films, respectively.

  4. Liquid crystal alignment on ZnO nanostructure films

    Science.gov (United States)

    Chung, Yueh-Feng; Chen, Mu-Zhe; Yang, Sheng-Hsiung; Jeng, Shie-Chang

    2016-03-01

    The study of liquid crystal (LC) alignment is important for fundamental researches and industrial applications. The tunable pretilt angles of liquid crystal (LC) molecules aligned on the inorganic zinc oxide (ZnO) nanostructure films with controllable surface wettability are demonstrated in this work. The ZnO nanostructure films are deposited on the ITO- glass substrates by the two-steps hydrothermal process, and their wettability can be modified by annealing. Our experimental results show that the pretilt angles of LCs on ZnO nanostructure films can be successfully adjusted over a wide range from ~90° to ~0° as the surface energy on the ZnO nanostructure films changes from ~30 to ~70 mJ/m. Finally we have applied this technique to fabricate a no-bias optically-compensated bend (OCB) LCD with ZnO nanostructure films annealed at 235 °C.

  5. Thermal Conductivity of Carbon Nanotube Composite Films

    Science.gov (United States)

    Ngo, Quoc; Cruden, Brett A.; Cassell, Alan M.; Walker, Megan D.; Koehne, Jessica E.; Meyyappan, M.; Li, Jun; Yang, Cary Y.

    2004-01-01

    State-of-the-art ICs for microprocessors routinely dissipate power densities on the order of 50 W/sq cm. This large power is due to the localized heating of ICs operating at high frequencies, and must be managed for future high-frequency microelectronic applications. Our approach involves finding new and efficient thermally conductive materials. Exploiting carbon nanotube (CNT) films and composites for their superior axial thermal conductance properties has the potential for such an application requiring efficient heat transfer. In this work, we present thermal contact resistance measurement results for CNT and CNT-Cu composite films. It is shown that Cu-filled CNT arrays enhance thermal conductance when compared to as-grown CNT arrays. Furthermore, the CNT-Cu composite material provides a mechanically robust alternative to current IC packaging technology.

  6. Capillary effects in guided crystallization of organic thin films

    Directory of Open Access Journals (Sweden)

    Alta Fang

    2015-03-01

    Full Text Available Recently, it has been demonstrated that solvent-vapor-induced crystallization of triethylsilylethynyl anthradithiophene (TES ADT thin films can be directed on millimeter length scales along arbitrary paths by controlling local crystal growth rates via pre-patterning the substrate. Here, we study the influence of capillary effects on crystallization along such channels. We first derive an analytical expression for the steady-state growth front velocity as a function of channel width and validate it with numerical simulations. Then, using data from TES ADT guided crystallization experiments, we extract a characteristic channel width, which provides the smallest feature size that can be obtained by this technique.

  7. Single Crystal Alloy Film Infrared Detectors.

    Science.gov (United States)

    1981-10-01

    evaporation; this excess chalco - genide is necessary to produce p-type lead salt epitaxial films. The tube was placed on the base plate of the evaporator with...maintain films of icomposition close to that of the source material (i.e., PbS0 .5Se0.5 ). hi -.The present conclusion concerninq use of the auxiliary chalco

  8. Electrophoretic deposition of composite halloysite nanotube–hydroxyapatite–hyaluronic acid films

    Energy Technology Data Exchange (ETDEWEB)

    Deen, I. [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Zhitomirsky, I., E-mail: zhitom@mcmaster.ca [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada)

    2014-02-15

    Highlights: ► Composite halloysite nanotubes–hydroxyapatite–hyaluronic acid films were prepared. ► Electrophoretic deposition method was used for deposition. ► Natural hyaluronic acid was used as a dispersing, charging and film forming agent. ► Film composition and deposition yield can be varied. ► The films can be used for biomedical implants with controlled release of drugs. -- Abstract: Electrophoretic deposition method has been developed for the deposition of biocomposite films containing halloysite nanotubes (HNTs), hydroxyapatite (HA) and hyaluronic acid. The method is based on the use of natural hyaluronate biopolymer as a dispersing and charging agent for HNT and HA and film forming agent for the fabrication of the composite films. The deposition kinetics was studied by the quartz crystal microbalance method. The composite films were studied by X-ray diffraction, thermogravimetric analysis, differential thermal analysis and electron microscopy. The composite films are promising materials for the fabrication of biomedical implants with advanced functional properties.

  9. Location control of crystal grains in excimer laser crystallization of silicon thin films

    Science.gov (United States)

    Kumomi, Hideya

    2003-07-01

    Location of crystal grains in polycrystalline Si thin films formed by excimer-laser crystallization is controlled by manipulating the superlateral-growth phenomenon. The superlateral growth of a single grain occurs preferentially at an artificial site where nanometer-sized crystallites are embedded in the precursory amorphous thin films. Only a part of the crystallites embedded in the site could survive the melting and grow to serve as the seed crystal in the subsequent recrystallization. Such grain-location control provides a basis for two-dimensional control of the grain-boundary location in low-temperature polycrystalline Si thin films, which is essential to the device-to-device uniformity of high-performance thin-film transistors.

  10. Applications of thin-film sandwich crystallization platforms

    Energy Technology Data Exchange (ETDEWEB)

    Axford, Danny, E-mail: danny.axford@diamond.ac.uk; Aller, Pierre; Sanchez-Weatherby, Juan; Sandy, James [Diamond Light Source, Harwell Oxford, Didcot OX11 0DE (United Kingdom)

    2016-03-24

    Crystallization via sandwiches of thin polymer films is presented and discussed. Examples are shown of protein crystallization in, and data collection from, solutions sandwiched between thin polymer films using vapour-diffusion and batch methods. The crystallization platform is optimal for both visualization and in situ data collection, with the need for traditional harvesting being eliminated. In wells constructed from the thinnest plastic and with a minimum of aqueous liquid, flash-cooling to 100 K is possible without significant ice formation and without any degradation in crystal quality. The approach is simple; it utilizes low-cost consumables but yields high-quality data with minimal sample intervention and, with the very low levels of background X-ray scatter that are observed, is optimal for microcrystals.

  11. Physiochemical Characterization of Iodine (V Oxide Part II: Morphology and Crystal Structure of Particulate Films

    Directory of Open Access Journals (Sweden)

    Brian K. Little

    2015-11-01

    Full Text Available In this study, the production of particulate films of iodine (V oxides is investigated. The influence that sonication and solvation of suspended particles in various alcohol/ketone/ester solvents have on the physical structure of spin or drop cast films is examined in detail with electron microscopy, powder x-ray diffraction, and UV-visible absorption spectroscopy. Results indicate that sonicating iodine oxides in alcohol mixtures containing trace amounts of water decreases deposited particle sizes and produces a more uniform film morphology. UV-visible spectra of the pre-cast suspensions reveal that for some solvents, the iodine oxide oxidizes the solvent, producing I2 and lowering the pH of the suspension. Characterizing the crystals within the cast films reveal their composition to be primarily HI3O8, their orientations to exhibit a preferential orientation, and their growth to be primarily along the ac-plane of the crystal, enhanced at higher spin rates. Spin-coating at lower spin rates produces laminate-like particulate films versus higher density, one-piece films of stacked particles produced by drop casting. The particle morphology in these films consists of a combination of rods, plates, cubes, and rhombohedra structure.

  12. Nonlinear optical properties of Au/PVP composite thin films

    Institute of Scientific and Technical Information of China (English)

    Shen Hong; Cheng Bo-Lin; Lu Guo-Wei; Wang Wei-Tian; Guan Dong-Yi; Chen Zheng-Hao; Yang Guo-Zhen

    2005-01-01

    Colloidal Au and poly(vinylpyrrolidone) (PVP) composite thin films are fabricated by spin-coating method. Linear optical absorption measurements of the Au/PVP composite films indicate an absorption peak around 530 nm due to the surface plasmon resonance of gold nanoparticles. Nonlinear optical properties are studied using standard Z-scan technique, and experimental results show large optical nonlinearities of the Au/PVP composite films. A large value of films.

  13. Model Lung Surfactant Films: Why Composition Matters

    Energy Technology Data Exchange (ETDEWEB)

    Selladurai, Sahana L.; Miclette Lamarche, Renaud; Schmidt, Rolf; DeWolf, Christine E.

    2016-10-18

    Lung surfactant replacement therapies, Survanta and Infasurf, and two lipid-only systems both containing saturated and unsaturated phospholipids and one containing additional palmitic acid were used to study the impact of buffered saline on the surface activity, morphology, rheology, and structure of Langmuir monolayer model membranes. Isotherms and Brewster angle microscopy show that buffered saline subphases induce a film expansion, except when the cationic protein, SP-B, is present in sufficient quantities to already screen electrostatic repulsion, thus limiting the effect of changing pH and adding counterions. Grazing incidence X-ray diffraction results indicate an expansion not only of the liquid expanded phase but also an expansion of the lattice of the condensed phase. The film expansion corresponded in all cases with a significant reduction in the viscosity and elasticity of the films. The viscoelastic parameters are dominated by liquid expanded phase properties and do not appear to be dependent on the structure of the condensed phase domains in a phase separated film. The results highlight that the choice of subphase and film composition is important for meaningful interpretations of measurements using model systems.

  14. Preparation of composite electroheat carbon film

    Institute of Scientific and Technical Information of China (English)

    XIA Jin-tong; TU Chuan-jun; LI Yan; HU Li-min; DENG Jiu-hua

    2005-01-01

    A kind of conductive and heating unit, which can reach a high surface electroheat temperature at a low voltage, was developed in view of the traditional electroheat coating which has a low surface electroheat temperature and an insufficient heat resistance of its binder. The coating molded electroheat carbon film(CMECF) was prepared by carbonizing the coating which was prepared by adding modified resin into flake graphite and carbon fiber, coating molded onto the surface of the heat resisting matrix after dried, while the hot pressing molded electroheat thick carbon film(HPMETCF) was prepared by carbonizing the bodies whose powders were hot pressing molded directly.The surface and inner microstructure of the carbon film was characterized and analyzed by SEM and DSC/TG, while electroheat property was tested by voltage-current volume resistivity tester and electrical parameter tester. The results show that, close-packed carbon network configuration is formed within the composite electroheat carbon film film after anti-oxidizable treatment reaches a higher surface electroheat temperature than that of the existing electroheat coatings at a low voltage, and has excellent electroheat property, high thermal efficiency as well as stable physicochemical property. It is found that, at room temperature(19± 2 ℃) and 22 V for 5 min, the surface electroheat temperature of the self-produced CMECF (mfiller/mresin = 1. 8/1) reaches 112 ℃ while HPMETCF (mfiller/mresin = 3. 6/1) reaches 265 ℃.

  15. Single crystal growth in spin-coated films of polymorphic phthalocyanine derivative under solvent vapor

    Energy Technology Data Exchange (ETDEWEB)

    Higashi, T.; Ohmori, M.; Ramananarivo, M. F.; Fujii, A., E-mail: afujii@opal.eei.eng.osaka-u.ac.jp; Ozaki, M. [Division of Electrical, Electronic, and Information Engineering, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan)

    2015-12-01

    The effects of solvent vapor on spin-coated films of a polymorphic phthalocyanine derivative were investigated. Growth of single crystal films via redissolving organic films under solvent vapor was revealed by in situ microscopic observations of the films. X-ray diffraction measurement of the films after exposing to solvent vapor revealed the phase transition of polymorphs under solvent vapor. The direction of crystal growth was clarified by measuring the crystal orientation in a grown monodomain film. The mechanism of crystal growth based on redissolving organic films under solvent vapor was discussed in terms of the different solubilities of the polymorphs.

  16. Single crystal growth in spin-coated films of polymorphic phthalocyanine derivative under solvent vapor

    Directory of Open Access Journals (Sweden)

    T. Higashi

    2015-12-01

    Full Text Available The effects of solvent vapor on spin-coated films of a polymorphic phthalocyanine derivative were investigated. Growth of single crystal films via redissolving organic films under solvent vapor was revealed by in situ microscopic observations of the films. X-ray diffraction measurement of the films after exposing to solvent vapor revealed the phase transition of polymorphs under solvent vapor. The direction of crystal growth was clarified by measuring the crystal orientation in a grown monodomain film. The mechanism of crystal growth based on redissolving organic films under solvent vapor was discussed in terms of the different solubilities of the polymorphs.

  17. ELECTROCHEMICAL STUDIES ON CONDUCTING COMPOSITE FILMS FROM POLYURETHANE AND POLYPYRROLE

    Institute of Scientific and Technical Information of China (English)

    BI Xiantong; PEI Qibing; LI Yongfang

    1988-01-01

    A study on the electrooxidative polymerization of pyrrole onto polyurethane-coated platinum electrodes and the electrochemical properties of the composite polyurethane/polypyrrole films (PU/PPy) as-prepared is presented. It is found that polypyrrole grows layer by layer from the polyurethane/platinum interface through the polyurethane matrix, and ca. 20 wt.% of polypyrrole will fill up the matrix. Cyclic voltammograms show that the composite films are porous, and the reduction-reoxidation (redox) rate of the composite films is limited by the diffusion ofcounteranions through the films. Larger anion size leads to slower diffusion process.The composite films can also act as modified electrodes.

  18. Thin film process forms effective electrical contacts on semiconductor crystals

    Science.gov (United States)

    Formigoni, N. P.; Roberts, J. S.

    1967-01-01

    Process makes microscopic, low-resistance electrical contacts on hexagonal n-type silicon carbide crystals used for microelectronic devices. A vacuum deposition of aluminum is etched to expose the bare silicon carbide where the electrical contacts are made. Sputtering alternating layers of tantalum and gold forms the alloy film.

  19. Separation and PurificationHomologous Compounds byof Dodecanedioic Acid from Its Falling Film Crystallization

    Institute of Scientific and Technical Information of China (English)

    李裕; 刘有智; 齐雪琴

    2004-01-01

    Separation and purification of dodecanedioic acid (DDDA) from its homologous compounds were studied experimentally by falling film crystallization (FFC). The influences of various operation parameters, including crystallizing time, flow rate of melt and temperature of glycerine bath, on purity of DDDA and crystallizing rate were investigated. Over 99% (by mole) DDDA was obtained for a feed composition of 96% (by mole). The main factors affecting the separation efficiency are flow rate of melt and temperature of glycerine bath. The crystallizing layer of DDDA was further purified by sweating and blasting. A set of optimized operation data are provided for better understanding the mechanism of heat and mass transfer in FFC, and for further industrial application of DDDA purification process.

  20. Investigation of polypyrrole/polyvinyl alcohol-titanium dioxide composite films for photo-catalytic applications

    Science.gov (United States)

    Cao, Shaoqiang; Zhang, Hongyang; Song, Yuanqing; Zhang, Jianling; Yang, Haigang; Jiang, Long; Dan, Yi

    2015-07-01

    Polypyrrole/polyvinyl alcohol-titanium dioxide (PPy/PVA-TiO2) composite films used as photo-catalysts were fabricated by combining TiO2 sol with PPy/PVA solution in which PPy was synthesized by in situ polymerization of pyrrole (Py) in polyvinyl alcohol (PVA) matrix and loaded on glass. The prepared photo-catalysts were investigated by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and photoluminescence (PL). The results indicate that the composites have same crystal structure as the TiO2 and extend the optic absorption from UV region to visible light region. By detecting the variation ratio, detected by ultraviolet-vis spectroscopy, of model pollutant rhodamine B (RhB) solution in the presence of the composite films under both UV and visible light irradiation, the photo-catalytic performance of the composite films was investigated. The results show that the PPy/PVA-TiO2 composite films show better photo-catalytic properties than TiO2 film both under UV and visible light irradiation, and the photo-catalytic degradation of RhB follows the first-order kinetics. The effects of the composition of composite films and the concentration of RhB on the photo-catalytic performance, as well as the possible photo-catalytic mechanism, were also discussed. By photo-catalytic recycle experiments, the structure stability of the PPy/PVA-TiO2 composite film was investigated and the results show that the photo-catalytic activity under both UV and visible light irradiation have no significant decrease after four times of recycle experiments, suggesting that the photo-catalyst film is stable during the photo-catalytic process, which was also confirmed by the XRD pattern and FT-IR spectra of the composite film before and after photo-catalytic.

  1. Evaluation of structure and mechanical properties of Ni-rich NiTi/Kapton composite film

    Energy Technology Data Exchange (ETDEWEB)

    Mohri, Maryam [Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nili-Ahmadabadi, Mahmoud [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); PouryazdanPanah, Mohsen; Hahn, Horst [Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Joint Research Labaratory Nanomaterials, Technische Universität Darmstadt, Darmstadt (Germany)

    2016-06-21

    NiTi thin films are usually sputtered on silicon wafers by magnetron sputtering. But the systems composed of thin film on flexible polymeric substrate are used in many applications such as micro electro-mechanical systems (MEMS). Investigation on mechanical properties of thin films has attracted much attention due to their widespread applications. In this paper, the mechanical properties of 1 µm-thick crystallized Ni-49.2 at%Ti thin film alloy deposited by DC magnetron sputtering on Kapton substrate are investigated by using tensile test. The as-deposited thin films are in amorphous state, then for crystallization, the thin film was annealed at 450 °C for 30 min. Formation of the austenite phase after annealing was confirmed by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The surface morphology of as deposited and crystallized thin films were examined by scanning electron microscopy (SEM). Stress-strain curves of the NiTi alloy thin film were obtained by subtracting of the stress-strain Kapton curves from the corresponding curves of the NiTi/Kapton composite. The XRD results revealed that the NiTi thin film deposited on the Kapton is austenitic and presents super-elastic effect at room temperature. This pseudo elastic effect leads to more recoverable strain in NiTi/Kapton composite film compared with Kapton foils on loading/unloading test. Furthermore, it was concluded that nanostructure of the NiTi thin film is responsible for remarkable improvement of ultimate tensile strength (1.4 GPa) at a strain of 30% compared with the bulk material.

  2. Preparation and Characterization of Chitosan-Agarose Composite Films.

    Science.gov (United States)

    Hu, Zhang; Hong, Pengzhi; Liao, Mingneng; Kong, Songzhi; Huang, Na; Ou, Chunyan; Li, Sidong

    2016-09-30

    Nowadays, there is a growing interest to develop biodegradable functional composite materials for food packaging and biomedicine applications from renewable sources. Some composite films were prepared by the casting method using chitosan (CS) and agarose (AG) in different mass ratios. The composite films were analyzed for physical-chemical-mechanical properties including tensile strength (TS), elongation-at-break (EB), water vapor transmission rate (WVTR), swelling ratio, Fourier-transform infrared spectroscopy, and morphology observations. The antibacterial properties of the composite films were also evaluated. The obtained results reveal that an addition of AG in varied proportions to a CS solution leads to an enhancement of the composite film's tensile strength, elongation-at-break, and water vapor transmission rate. The composite film with an agarose mass concentration of 60% was of the highest water uptake capacity. These improvements can be explained by the chemical structures of the new composite films, which contain hydrogen bonding interactions between the chitosan and agarose as shown by Fourier-transform infrared spectroscopy (FTIR) analysis and the micro-pore structures as observed with optical microscopes and scanning electron microscopy (SEM). The antibacterial results demonstrated that the films with agarose mass concentrations ranging from 0% to 60% possessed antibacterial properties. These results indicate that these composite films, especially the composite film with an agarose mass concentration of 60%, exhibit excellent potential to be used in food packaging and biomedical materials.

  3. Al-Induced Crystallization Growth of Si Films by Inductively Coupled Plasma Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    LI Jun-Shuai; WANG Jin-Xiao; YIN Min; GAO Ping-Qi; HE De-Yan

    2006-01-01

    Polycrystalline Si (poly-Si) films are in situ grown on Al-coated glass substrates by inductively coupled plasma chemical vapour deposition at a temperature as low as 350 C. Compared to the traditional annealing crystallization of amorphous Si/Al-layer structures, no layer exchange is observed and the resultant poly-Si film is much thicker than Al layer. By analysing the depth profiles of the elemental composition, no remains of Al atoms are detected in Si layer within the limit (< 0.01 at. %) of the used evaluations. It is indicated that the poly-Si material obtained by Al-induced crystallization growth has more potential applications than that prepared by annealing the amorphous Si/Al-layer structures.

  4. Compositional-induced structural change in Zr{sub x}Ni{sub 100−x} thin film metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ghidelli, Matteo, E-mail: matteo.ghidelli@simap.grenoble-inp.fr [Science and Engineering of Materials and Processes, SIMaP, Université de Grenoble/CNRS, UJF/Grenoble INP, BP46, 38402 Saint-Martin d’Hères (France); Institute of Mechanics, Materials and Civil Engineering, IMMC, Université catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Institute of Information and Communication Technologies, Electronics and Applied Mathematics, ICTEAM, Université catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Gravier, Sébastien; Blandin, Jean-Jacques [Science and Engineering of Materials and Processes, SIMaP, Université de Grenoble/CNRS, UJF/Grenoble INP, BP46, 38402 Saint-Martin d’Hères (France); Pardoen, Thomas [Institute of Mechanics, Materials and Civil Engineering, IMMC, Université catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Raskin, Jean-Pierre [Institute of Information and Communication Technologies, Electronics and Applied Mathematics, ICTEAM, Université catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Mompiou, Frédéric [CEMES-CNRS, Université de Toulouse, 29, rue J. Marvig, 31005 Toulouse (France)

    2014-12-05

    Highlights: • A composite ZrNi target is used to accurately tune ZrNi thin film composition. • The atomic structure of metallic glass films is determined for several compositions. • Short and medium range order is inferred for amorphous compositions. • Crystallization phenomena are detected for Zr-rich specimens. • Crystallization is justified on the basis Nagel and Tauc criterion. - Abstract: The structure of Zr{sub x}Ni{sub 100−x} thin film metallic glasses (TFMGs) has been studied for a variety of compositions obtained by DC magnetron sputtering using a composite ZrNi target. The crystallization has been characterized by X-ray diffraction and transmission electron microscopy revealing also short and medium range order for amorphous compositions. The TFMGs thermodynamic stability has been evaluated by exploiting the Nagel and Tauc criterion, justifying the occurrence of crystallization in the Zr-rich specimens.

  5. Crystallization kinetics of poly(lactic acid)-talc composites

    OpenAIRE

    Battegazzore, Daniele; Bocchini, Sergio; Frache, Alberto

    2011-01-01

    The crystallization kinetics of Poly(lactic acid) / talc composites were determined over a range of 0 wt.% to 15 wt.% of talc. Talc was found to change the crystallization kinetics. The presence of talc increases the crystallization rate and this increase is related to talc concentration and to crystallization temperature. In order to understand the effect of talc and PLA crystallinity on mechanical properties, dynamic mechanical thermal analyses were performed on Poly(lactic acid) / talc com...

  6. Electrical domain morphologies in compositionally graded ferroelectric films.

    Science.gov (United States)

    Okatan, M B; Roytburd, A L; Nagarajan, V; Alpay, S P

    2012-01-18

    We present a nonlinear thermodynamic formalism coupled with an electrostatic analysis of uniaxial n-layered compositionally graded heteroepitaxial ferroelectric films and extend this formalism to continuously graded ferroelectric films. We show that the domain morphology and its subsequent evolution in the presence of an electric field are determined by the spontaneous polarisation of the film induced through the compositional grading. The results for compositionally graded epitaxial (001) (Ba,Sr)TiO(3) and (001) Pb(Zr,Ti)O(3) films on (001)SrTiO(3) demonstrate that, while the domain morphologies in these two films are different in appearance, the dielectric displacement and the dielectric permittivity of such graded ferroelectric films exhibit a strong nonlinear behaviour which results in a high dielectric tunability. These findings indicate that it is possible to design specific domain structures that will yield desirable dielectric properties by controlling the strength of the compositional grading in the films.

  7. Structure and composition effects on electrical and optical properties of sputtered PbSe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xigui; Gao, Kewei [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Pang, Xiaolu, E-mail: pangxl@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yang, Huisheng [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Volinsky, Alex A. [Department of Mechanical Engineering, University of South Florida, Tampa, FL 33620 (United States)

    2015-10-01

    Lead selenide (PbSe) thin films were grown on Si (111) substrates using magnetron sputtering, and the structure and composition effects on the photoelectric and optical properties of the sputtered PbSe thin films were studied using field emission scanning electron microscope, energy dispersive X-ray detector, X-ray diffraction, X-ray photoelectron spectroscopy, physical property measurement system and Fourier transform infrared spectroscopy. The optical band gaps of all the sputtered PbSe thin films ranged from 0.264 eV to 0.278 eV. The PbSe thin film prepared with oxygen flux 1.0 sccm, deposition time 240 min, sputtering power 150 W and substrate temperature 150 °C showed the highest resistance change rate under illumination, about 84.47%. The variation trends of the photoelectric and optical properties with the average crystal size, lattice constant, oxygen content and lattice oxygen percentage were similar, respectively. The sputtered PbSe thin films showed poor photoelectric sensitivity, when the average crystal size was similar to the Bohr radius (46 nm), while the photoelectric sensitivity increased almost linearly with the oxygen content in the thin films, indicating that both deviating the average crystal size from the Bohr radius and increasing the oxygen content are two direct and effective ways to obtain high photoelectric sensitivity in PbSe thin films. - Highlights: • Lead selenide thin films were grown on Si (111) using magnetron sputtering. • Lead selenide thin films show superior photoelectric sensitivity. • The effects of structure and composition to the film properties were studied. • The photoelectric property was mainly affected by grain size and oxygen content.

  8. Hydrogenation of Laser-crystallized a-Si:H Films

    Directory of Open Access Journals (Sweden)

    M.V. Khenkin

    2015-10-01

    Full Text Available Ultrafast laser processing of semiconductors is a rapidly developing field of material science at the moment. In particular, femtosecond laser crystallization of amorphous hydrogenated silicon thin films has a big potential in photovoltaics. However laser treatment causes dehydrogenation process which decreases materials’ photosensitivity and thus limiting its application for optoelectronics. In present paper we studied photoelectric properties of laser-modified amorphous silicon films. Two different hydrogenation procedures were employed to restore films’ hydrogen content: keeping in hydrogen plasma and in high-pressure hydrogen atmosphere. The effectiveness of applied procedures for increasing materials’ photosensitivity is discussed.

  9. Study on the crystal morphology and melting behavior of isothermally crystallized composites of short carbon fiber and poly(trimethylene terephthalate)

    Institute of Scientific and Technical Information of China (English)

    Mingtao RUN; Hongzan SONG; Yanping HAO

    2009-01-01

    The spherulites of the short carbon fibcr(SCF)/ poly (trimethylcne terephthalate) (PTT) composites forrned in limited space at designed temperatures, and their melting behaviors were studied by the polarized optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), respectively. The results suggest that SCF content, isothermal crystallization temperatures, and the film thicknesses influence the crystal morphology of the composites. The dimension of the spherulites is decreased with increasing SCF content, but whether banded or nonbandcd spherulites will form in the composites is not depondcnt on SCF content However, the crystal morphology of the composites depends strongly on the temperature. When the isothermal crystallization temperatures increase from 180℃ to 230℃, the crystal morphology of SCF/PTT composites continuously changes in the following order: nonbanded → banded → nonbanded spherulites. Disconti-nuous circle lines form in the film when the film thickness increases from 30 to 60 μm. Basing on the SEM observation, it is found that these circle lines are cracks formed due to the constriction difference of the different parts of the sphemlites. These cracks are formed when the film is cooled from the isothermal crystallization temperature to the room tempera-ture at a slow cooling rate; while they will disappear gradually at different temperatures in the heating process. The crack will appear/disappear first around the center of the spherulite when the film was cooled/heated. The nontwisted or slightly twisted lamellas will reorganize to form highly twisted lamellas inducing apparent banded texture of the sphemlites.

  10. Size effects in single crystal thin films : nonlocal crystal plasticity simulations

    NARCIS (Netherlands)

    Yefimov, S; van der Giessen, E

    2005-01-01

    Stress relaxation in single crystalline thin films on substrates subjected to thermal loading is studied using a recently proposed nonlocal continuum crystal plasticity theory. The theory is founded on a statistical-mechanics description of the collective behaviour of dislocations in multiple slip,

  11. Nanocrystalline silicon films prepared by laser-induced crystallization

    Institute of Scientific and Technical Information of China (English)

    傅广生; 于威; 李社强; 侯海虹; 彭英才; 韩理

    2003-01-01

    The excimer laser-induced crystallization technique has been used to investigate the preparation of nanocrystalline silicon (nc-Si) from amorphous silicon (α-Si) thin films on silicon or glass substrates. The α-Si films without hydrogen grown by pulsed-laser deposition are chosen as precursor to avoid the problem of hydrogen effluence during annealing.Analyses have been performed by scanning electron microscopy, atomic force microscopy, Raman scattering spectroscopy and high-resolution transmission-electron microscopy. Experimental results show that silicon nanocrystals can be formed through laser annealing. The growth characters of nc-Si are strongly dependent on the laser energy density. It is shown that the volume of the molten silicon predominates essentially the grain size of nc-Si, and the surface tension of the crystallized silicon is responsible for the mechanism of nc-Si growth.

  12. Effect of Initial Bulk Material Composition on Thermoelectric Properties of Bi2Te3 Thin Films

    Science.gov (United States)

    Budnik, A. V.; Rogacheva, E. I.; Pinegin, V. I.; Sipatov, A. Yu.; Fedorov, A. G.

    2013-07-01

    V2VI3 compounds and solid solutions based on them are known to be the best low-temperature thermoelectric (TE) materials. The predicted possibility of enhancement of the TE figure of merit in two-dimensional (2D) structures has stimulated studies of the properties of these materials in the thin-film state. The goal of the present work is to study the dependences of the Seebeck coefficient S, electrical conductivity σ, Hall coefficient R H, charge carrier mobility μ H, and TE power factor P = S 2 σ of Bi2Te3 thin films on the composition of the initial bulk material used for preparing them. Thin films with thickness d = 200 nm to 250 nm were grown by thermal evaporation in vacuum of stoichiometric Bi2Te3 crystals (60.0 at.% Te) and of crystals with 62.8 at.% Te onto glass substrates at temperatures T S of 320 K to 500 K. It was established that the conductivity type of the initial material is reproduced in films fairly well. For both materials, an increase in T S leads to an increase in the thin-film structural perfection, better correspondence between the film composition and that of the initial material, and increase in S, R H, μ H, σ, and P. The room-temperature maximum values of P for the films grown from crystals with 60.0 at.% and 62.8 at.% Te are P = 7.5 × 10-4 W/K2 m and 35 × 10-4 W/K2 m, respectively. Thus, by using Bi2Te3 crystals with different stoichiometry as initial materials, one can control the conductivity type and TE parameters of the films, applying a simple and low-cost method of thermal evaporation from a single source.

  13. Preparation and Characterization of Chitosan—Agarose Composite Films

    Directory of Open Access Journals (Sweden)

    Zhang Hu

    2016-09-01

    Full Text Available Nowadays, there is a growing interest to develop biodegradable functional composite materials for food packaging and biomedicine applications from renewable sources. Some composite films were prepared by the casting method using chitosan (CS and agarose (AG in different mass ratios. The composite films were analyzed for physical-chemical-mechanical properties including tensile strength (TS, elongation-at-break (EB, water vapor transmission rate (WVTR, swelling ratio, Fourier-transform infrared spectroscopy, and morphology observations. The antibacterial properties of the composite films were also evaluated. The obtained results reveal that an addition of AG in varied proportions to a CS solution leads to an enhancement of the composite film’s tensile strength, elongation-at-break, and water vapor transmission rate. The composite film with an agarose mass concentration of 60% was of the highest water uptake capacity. These improvements can be explained by the chemical structures of the new composite films, which contain hydrogen bonding interactions between the chitosan and agarose as shown by Fourier-transform infrared spectroscopy (FTIR analysis and the micro-pore structures as observed with optical microscopes and scanning electron microscopy (SEM. The antibacterial results demonstrated that the films with agarose mass concentrations ranging from 0% to 60% possessed antibacterial properties. These results indicate that these composite films, especially the composite film with an agarose mass concentration of 60%, exhibit excellent potential to be used in food packaging and biomedical materials.

  14. Photonic Crystal Cavities in Cubic Polytype Silicon Carbide Films

    CERN Document Server

    Radulaski, Marina; Buckley, Sonia; Rundquist, Armand; Provine, J; Alassaad, Kassem; Ferro, Gabriel; Vučković, Jelena

    2013-01-01

    We present the design, fabrication, and characterization of high quality factor and small mode volume planar photonic crystal cavities from cubic (3C) thin films (thickness ~ 200 nm) of silicon carbide (SiC) grown epitaxially on a silicon substrate. We demonstrate cavity resonances across the telecommunications band, with wavelengths from 1250 - 1600 nm. Finally, we discuss possible applications in nonlinear optics, optical interconnects, and quantum information science.

  15. Alginate-magnesium aluminum silicate composite films: effect of film thickness on physical characteristics and permeability.

    Science.gov (United States)

    Pongjanyakul, Thaned; Puttipipatkhachorn, Satit

    2008-01-04

    The different film thicknesses of the sodium alginate-magnesium aluminum silicate (SA-MAS) microcomposite films were prepared by varying volumes of the composite dispersion for casting. Effect of film thickness on thermal behavior, solid-state crystallinity, mechanical properties, water uptake and erosion, and water vapor and drug permeability of the microcomposite films were investigated. The film thickness caused a small change in thermal behavior of the films when tested using DSC and TGA. The crystallinity of the thin films seemed to increase when compared with the thick films. The thin films gave higher tensile strength than the thick films, whereas % elongation of the films was on the contrary resulted in the lower Young's modulus of the films when the film thickness was increased. This was due to the weaker of the film bulk, suggesting that the microscopic matrix structure of the thick films was looser than that of the thin films. Consequently, water uptake and erosion, water vapor permeation and drug diffusion coefficient of the thick films were higher than those of the thin films. The different types of drug on permeability of the films also showed that a positive charge and large molecule of drug, propranolol HCl, had higher lag time and lower diffusion coefficient that acetaminophen, a non-electrolyte and small molecule. This was because of a higher affinity of positive charge drug on MAS in the films. The findings suggest that the evaporation rate of solvent in different volumes of the composite dispersion used in the preparation method could affect crystallinity and strength of the film surface and film bulk of the microcomposite films. This led to a change in water vapor and drug permeability of the films.

  16. Role of the Confined Geometry on the Crystallization of Poly(ethylene terephthlate) Ultrathin Films

    Institute of Scientific and Technical Information of China (English)

    Ying ZHANG; Yong Lai LU; De Yan SHEN

    2005-01-01

    The reflection-absorption infrared (RAIR) was employed to study the crystallization kinetic of poly (ethylene terephthalate) (PET) ultrathin films. During isothermal crystallization the thinner PET film shows a slower kinetic compared with the thicker film. Moreover, the final crystallinity of films with various thickness was found decrease with thickness. The result of fitting our data to Avrami equation showed that the Avrami exponents decrease with film thickness.

  17. Phenocryst compositional diversity as a consequence of degassing induced crystallization

    Science.gov (United States)

    Frey, H. M.; Lange, R. A.

    2006-12-01

    In volcanic arc lavas, compositional diversity in phenocryst populations has commonly been attributed to magma mingling or mixing. However, the amount of dissolved water in the magma appears to have a significant effect on composition of the phenocrysts that crystallize from the melt. Tens of plagioclase and pyroxene phenocrysts were analyzed from six crystal-poor (Tequila in western Mexico. The compositions and phase assemblages in the crystal-poor lavas are remarkably similar to that of the crystal-rich lavas (15-30 vol%) from the main edifice and flank flows of Volcán Tequila. Both lava types have plagioclase phenocrysts that span a wide compositional range, up to 45 mol% anorthite. In the crystal-rich lavas, individual phenocrysts have significant compositional variation, from oscillatory zoning of tens of mol% to relatively homogenous composition cores with a 5-10 um rim of significantly different composition. In contrast, plagioclase in the crystal-poor lavas has compositional variation within the population, but not individual phenocrysts. The plagioclase have little core to rim zoning and remarkable euhedral shapes, irrespective of composition. They are often riddled with melt inclusion channels, which broadly parallel the long axis of the crystal. These textures have been recognized in plagioclase crystallization experiments to be the result of rapid and large degrees of undercooling during crystallization. In the crystal-poor lavas, there is no textural evidence to suggest the phenocrysts were ever out of equilibrium with the host magma, so an alternative to magma mingling/mixing must be considered. The composition of plagioclase is dependent on several parameters, but varies most strongly with H2O content. Because of this relationship, a new plagioclase hygrometer (Lange and Frey, 2006) calibrated on plagioclase compositions from water-saturated experiments in the literature, can be used to determine the dissolved water content in the magma from which

  18. Single-layer nano-carbon film, diamond film, and diamond/nano-carbon composite film field emission performance comparison

    Science.gov (United States)

    Wang, Xiaoping; Wang, Jinye; Wang, Lijun

    2016-05-01

    A series of single-layer nano-carbon (SNC) films, diamond films, and diamond/nano-carbon (D/NC) composite films have been prepared on the highly doped silicon substrate by using microwave plasma chemical vapor deposition techniques. The films were characterised by scanning electron microscopy, Raman spectroscopy, and field emission I-V measurements. The experimental results indicated that the field emission maximum current density of D/NC composite films is 11.8-17.8 times that of diamond films. And the field emission current density of D/NC composite films is 2.9-5 times that of SNC films at an electric field of 3.0 V/μm. At the same time, the D/NC composite film exhibits the advantage of improved reproducibility and long term stability (both of the nano-carbon film within the D/NC composite cathode and the SNC cathode were prepared under the same experimental conditions). And for the D/NC composite sample, a high current density of 10 mA/cm2 at an electric field of 3.0 V/μm was obtained. Diamond layer can effectively improve the field emission characteristics of nano-carbon film. The reason may be due to the diamond film acts as the electron acceleration layer.

  19. Improved thermal stability of polylactic acid (PLA) composite film via PLA-β-cyclodextrin-inclusion complex systems.

    Science.gov (United States)

    Byun, Youngjae; Rodriguez, Katia; Han, Jung H; Kim, Young Teck

    2015-11-01

    The effects of the incorporation of PLA-β-cyclodextrin-inclusion complex (IC) and β-cyclodextrin (β-CD) on biopolyester PLA films were investigated. Thermal stability, surface morphology, barrier, and mechanical properties of the films were measured at varying IC (1, 3, 5, and 7%) and β-CD (1 and 5%) concentrations. The PLA-IC-composite films (IC-PLA-CFs) showed uniform morphological structure, while samples containing β-CD (β-CD-PLA-CFs) showed high agglomeration of β-CD due to poor interfacial interaction between β-CD and PLA moieties. According to the thermal property analysis, the 5% IC-PLA-CFs showed 6.6 times lower dimensional changes (6.5%) at the temperature range of 20-80°C than that of pure PLA film (43.0%). The increase of IC or β-CD content in the PLA-composite films shifted the glass transition and crystallization temperature to higher temperature regions. The crystallinity of both composite films improved by increasing IC or β-CD content. Both composite films had higher oxygen and water vapor permeability as IC or β-CD content increased in comparison to pure PLA film. All the composite films had less flexibility and lower tensile strength than the pure PLA film. In conclusion, this study shows that the IC technique is valuable to improve the thermal expansion stability of PLA-based films.

  20. Composite Films Based on Hydroxyapatite and Polyvinyl Alcohol

    Directory of Open Access Journals (Sweden)

    O.N. Musskaya

    2015-03-01

    Full Text Available Composite films based on hydroxyapatite (HA gel and polyvinyl alcohol (PVA were obtained. Light scattering of composite films in the PVA film is increased with growth of HA content from 0.5 to 33.0 %. The introduction of HA in PVA film leads to the inhibition of thermal degradation of the polymer without changing the position of the main spectral bands in UV-Vis absorption spectra. The introduction of HA into the PVA film promotes their hydrophobicity, while UV light leads to the significant increase in the hydrophilicity, especially after its heating at 180 °C.

  1. Synthesis of Photochromic AgCl-Urethane Resin Composite Films

    Directory of Open Access Journals (Sweden)

    Hidetoshi Miyazaki

    2012-01-01

    Full Text Available AgCl-resin photochromic composite films were prepared using AgNO3, HCl-EtOH, CuCl2 solution, and a liquid-state urethane resin as starting materials. The obtained composite films showed a photochromic property. The rate of darkening of the composite film increased after mixing with CuCl2. The AgCl particle size in the film without heat treatment was 6–20 nm, and that of the heat-treated film was 25–80 nm; these results were confirmed using TEM observations. The fading rate of the film without heat treatment was higher than that of the heat-treated films.

  2. Electrochemical Formation of Polypyrrole-carboxymethylcellulose Conducting Polymer Composite Films

    Institute of Scientific and Technical Information of China (English)

    H.N.M. Ekramul Mahmud; Anuar Kassim; Zulkarnain Zainal; Wan Mahmood Mat Yunus

    2005-01-01

    The electrochemical preparation of polypyrrole-carboxymethylcellulose (PPY-CMC) conducting polymer composite films on indium tin oxide (ITO) glass electrode from an aqueous solution containing pyrrole monomer, ptoluenesulfonate electrolyte and carboxymethylcellulose insulating polymer is reported. The characterization by Fourier transform infrared spectroscopy (FT-IR) shows that carboxymethylcellulose (CMC) has been successfully incorporated into polypyrrole structure forming PPY-CMC polymer composite films. The conductivity of the prepared composite films was found to increase with increaseing CMC concentration in pyrrole solution. The optical microscopic results show the influence of CMC concentration in the pyrrole solution over the morphological changes of the prepared films. The dynamic mechanical analysis (DMA) on the prepared PPY-CMC film reveals the higher plastic property of the PPY-CMC composite film.

  3. Applications of thin-film sandwich crystallization platforms.

    Science.gov (United States)

    Axford, Danny; Aller, Pierre; Sanchez-Weatherby, Juan; Sandy, James

    2016-04-01

    Examples are shown of protein crystallization in, and data collection from, solutions sandwiched between thin polymer films using vapour-diffusion and batch methods. The crystallization platform is optimal for both visualization and in situ data collection, with the need for traditional harvesting being eliminated. In wells constructed from the thinnest plastic and with a minimum of aqueous liquid, flash-cooling to 100 K is possible without significant ice formation and without any degradation in crystal quality. The approach is simple; it utilizes low-cost consumables but yields high-quality data with minimal sample intervention and, with the very low levels of background X-ray scatter that are observed, is optimal for microcrystals.

  4. Thin-Film Behavior of Poly(methyl methacrylates). 3. Epitaxial Crystallization in Thin Films of Isotactic Poly(methyl methacrylate) Using Crystalline Langmuir-Blodgett Layers

    NARCIS (Netherlands)

    Brinkhuis, R.H.G.; Schouten, A.J.

    1992-01-01

    A procedure is introduced using monolayer crystallized films of isotactic poly(methyl methacrylate) (i-PMMA) to induce crystallization in amorphous films of i-PMMA. Use of the Langmuir-Blodgett films as surface crystallization nuclei permits the preparation of highly crystalline films with thickness

  5. Green laser crystallization of GeSi thin films and dopant activation

    NARCIS (Netherlands)

    Rangarajan, Balaji; Brunets, Ihor; Oesterlin, Peter

    2011-01-01

    Laser-crystallization of amorphous $Ge_{0.85}Si_{0.15}$ films is studied, using green laser scanning and preformed topography to steer the crystallization. Large crystals (8x2 $\\mu m^2$) are formed with location-controlled grain boundaries. The obtained films were characterized using Scanning Electr

  6. Properties of laser-crystallized polycrystalline SiGe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Weizman, Moshe

    2008-06-06

    In this thesis, structural, electrical, and optical properties of laser-crystallized polycrystalline Si{sub 1-x}Ge{sub x} thin films with 0crystallization of amorphous Si{sub 1-x}Ge{sub x} thin films with 0.3film, which is directly coupled to a periodic compositional variation. - Amorphous SiGe samples that are exposed to a single laser pulse exhibit a ripple structure that evolves into a hillock structure when the samples are irradiated with additional laser pulses. - It is maintained that the main mechanism behind the structure formation is an instability of the propagating solid-liquid interface during solidification. - The study of defects with electron spin resonance showed that laser-crystallized poly-Si{sub 1-x}Ge{sub x} thin films with 0crystallization method and Ge content. The defect density for solid-phase crystallized SiGe films was lower and amounted to N{sub s}=7 x 10{sup 17} cm{sup -3}. - Germanium-rich laser-crystallized poly-SiGe thin films exhibited mostly a broad atypical electric dipole spin resonance (EDSR) signal that was accompanied by a nearly temperature-independent electrical conductivity in the range 20-100 K. - Most likely, the origin of the grain boundary conductance is due to dangling-bond defects and not impurities. Metallic-like conductance occurs when the dangling-bond defect density is above a critical value of about N{sub C} {approx} 10{sup 18} cm{sup -3}. - Laser crystallized poly-Si{sub 1-x}Ge{sub x} thin films with x{>=}0.5 exhibit optical absorption behavior that is characteristic for disordered SiGe, implying that the absorption occurs primarily at the grain boundaries. A sub-band-gap absorption peak was found for

  7. In-situ X-ray diffraction studies of time and thickness dependence of crystallization of amorphous TiO{sub 2} thin films and stress evolution

    Energy Technology Data Exchange (ETDEWEB)

    Kuzel, R., E-mail: kuzel@karlov.mff.cuni.c [Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University in Prague, 121 16 Praha 2 (Czech Republic); Nichtova, L.; Matej, Z. [Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University in Prague, 121 16 Praha 2 (Czech Republic); Musil, J. [Department of Physics, Faculty of Applied Sciences, University of West Bohemia in Pilsen, Pilsen (Czech Republic)

    2010-12-30

    Remarkable properties of titanium dioxide films such as hydrophilicity or photocatalytic activity depend largely on their phase composition, microstructure and in particular on the crystallinity. By in-situ X-ray diffraction studies of isochronal and isothermal annealing of amorphous films with different thickness at different temperatures it was found that the crystallization process can be quite well described by the Johnson-Mehl-Avrami-Kolmogorov formula modified by the introduction of crystallization onset. This and other parameters of the formula strongly depend on the film thickness. For thickness below about 500 nm the crystallization is very slow. Simultaneously, the appearance and increase of tensile stresses with the annealing time were observed and these stresses were confirmed by detailed studies by both total pattern fitting and sin{sup 2{psi}} method on post-annealed samples. The stresses rapidly increase with decreasing thickness of the films. It seems that there is a strong correlation between the stresses and crystallization onset and/or crystallization rate. Tensile stresses that are generated during crystallization further inhibit crystallization and cause significant thickness dependence of the crystallization. The temperature and time dependence of microstructure of crystallized amorphous films differ significantly from those obtained for as-deposited nanocrystalline films or nanocrystalline powders. During annealing, quite large crystallites are formed quickly with the preferred orientation (001) that is suppressed with the proceeding time.

  8. Investigation of polypyrrole/polyvinyl alcohol–titanium dioxide composite films for photo-catalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Shaoqiang; Zhang, Hongyang; Song, Yuanqing; Zhang, Jianling; Yang, Haigang; Jiang, Long, E-mail: jianglong@scu.edu.cn; Dan, Yi, E-mail: danyichenweiwei@163.com

    2015-07-01

    Graphical abstract: - Highlights: • The study provides an easy and convenient method to fabricate films, which will give guidance for the preparation of three-dimensional materials. • The PPy/PVA–TiO{sub 2} films can keep better photo-catalytic activities both under UV and visible light irradiation when compared with TiO{sub 2} film. • There exist electron transfers between PPy/PVA and TiO{sub 2}. - Abstract: Polypyrrole/polyvinyl alcohol–titanium dioxide (PPy/PVA–TiO{sub 2}) composite films used as photo-catalysts were fabricated by combining TiO{sub 2} sol with PPy/PVA solution in which PPy was synthesized by in situ polymerization of pyrrole (Py) in polyvinyl alcohol (PVA) matrix and loaded on glass. The prepared photo-catalysts were investigated by X-ray diffraction (XRD), ultraviolet–visible diffuse reflection spectroscopy (UV–vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and photoluminescence (PL). The results indicate that the composites have same crystal structure as the TiO{sub 2} and extend the optic absorption from UV region to visible light region. By detecting the variation ratio, detected by ultraviolet–vis spectroscopy, of model pollutant rhodamine B (RhB) solution in the presence of the composite films under both UV and visible light irradiation, the photo-catalytic performance of the composite films was investigated. The results show that the PPy/PVA–TiO{sub 2} composite films show better photo-catalytic properties than TiO{sub 2} film both under UV and visible light irradiation, and the photo-catalytic degradation of RhB follows the first-order kinetics. The effects of the composition of composite films and the concentration of RhB on the photo-catalytic performance, as well as the possible photo-catalytic mechanism, were also discussed. By photo-catalytic recycle experiments, the structure stability of the PPy/PVA–TiO{sub 2} composite film was investigated and the results show that

  9. Thin and flexible solid-state organic ionic plastic crystal-polymer nanofibre composite electrolytes for device applications.

    Science.gov (United States)

    Howlett, Patrick C; Ponzio, Florian; Fang, Jian; Lin, Tong; Jin, Liyu; Iranipour, Nahid; Efthimiadis, Jim

    2013-09-07

    All solid-state organic ionic plastic crystal-polymer nanofibre composite electrolytes are described for the first time. The new composite materials exhibit enhanced conductivity, excellent thermal, mechanical and electrochemical stability and allow the production of optically transparent, free-standing, flexible, thin film electrolytes (10's μms thick) for application in electrochemical devices. Stable cycling of a lithium cell incorporating the new composite electrolyte is demonstrated, including cycling at lower temperatures than previously possible with the pure material.

  10. Dielectric and Energy Storage Properties of the Heterogeneous P(VDF-HFP)/PC Composite Films

    Science.gov (United States)

    Zhao, Xiaojia; Peng, Guirong; Zhan, Zaiji

    2016-09-01

    Polymer-based materials with a high discharge energy and low energy loss have attracted considerable attention for energy storage applications. A new class of polymer-based composite films composed of amorphous polycarbonate (PC) and poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] has been fabricated by simply solution blending followed by thermal treatment under vacuum. The results show that the diameter of the spherical phase for PC and the melting temperature of P(VDF-HFP) increase, and the crystallinity and crystallization temperature of P(VDF-HFP) decrease with increasing PC content. The phase transition from the polar β phase to weak polarity γ phase is induced by PC addition. Moreover, the Curie temperature of the P(VDF-HFP)/PC composite films shifts to a lower temperature. With the addition of PC, the permittivity, polarization and discharge energy of the P(VDF-HFP)/PC composite films slightly decrease. However, the energy loss is significantly reduced.

  11. Molecular ordering and 2D conductivity in ultrathin poly(3-hexylthiophene)/gold nanoparticle composite films.

    Science.gov (United States)

    Ruiz, Virginia; Nicholson, Patrick G; Jollands, Stuart; Thomas, Pamela A; Macpherson, Julie V; Unwin, Patrick R

    2005-10-20

    This paper reports the first comparison of the structure and electrical conductivity properties of spin cast (SC) and Langmuir-Schaeffer (LS) films of regioregular poly(3-hexylthiophene) (P3HT). In addition, the effect of incorporating highly monodisperse Au nanoparticles (NPs), with a core diameter of approximately 5 nm, into SC and LS P3HT films is described. A detailed picture of molecular organization in the films has been obtained using ultraviolet-visible absorption spectroscopy, atomic force microscopy, field-emission scanning electron microscopy, X-ray diffraction, and X-ray reflectivity. Film morphology was correlated with pseudo-two-dimensional conductivity measured using scanning electrochemical microscopy, with P3HT in the semiconducting regime. It was found that SC films, which were slightly thicker than those formed with the LS technique, exhibited greater organization. This resulted in an order of magnitude higher lateral conductivity for the SC films. Inclusion of Au NPs (50 wt %) into both SC and LS films resulted in the formation of uniform and relatively flat (rms roughness approximately 1 nm) composite films. Surprisingly, the addition of NPs did not disrupt the characteristic crystal structure found for the native P3HT films. The effect of Au NPs on film lateral conductivity was found to be determined by the distribution of Au NPs within the polymer, which varied significantly between SC and LS films. Whereas Au NPs aggregated into hexagonally packed clusters in SC films, NPs in LS films were predominantly uniformly distributed between the lamella bilayer. It was found that, while the inclusion of Au NPs caused the lateral conductivity to decrease in SC films, in LS films, the lateral conductivity increased by a factor of 2.

  12. Enhanced stability and mechanical strength of sodium alginate composite films.

    Science.gov (United States)

    Liu, Sijun; Li, Yong; Li, Lin

    2017-03-15

    This work aims to study how three kinds of nanofillers: graphene oxide (GO), ammonia functionalized graphene oxide (AGO), and triethoxylpropylaminosilane functionalized silica, can affect stability and mechanical strength of sodium alginate (SA) composite films. The filler/sodium alginate (SA) solutions were first studied by rheology to reveal effects of various fillers on zero shear viscosity η0. SA composite films were then prepared by a solution mixing-evaporation method. The structure, morphology and properties of SA composite films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), contact angle and mechanical testing. Compared to GO and silica, the presence of AGO significantly improved the interaction between AGO and SA, which led to the increase in stability and mechanical strength of the resulting SA composite films. The tensile strength and elongation at break of AGO/SA composite film at 3wt% AGO loading were increased by 114.9% and 194.4%, respectively, in contrast to pure SA film. Furthermore, the stability of AGO/SA composite films at high temperatures and in a wet environment were better than that of silica/SA and GO/SA composite films. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Crystallization behavior and glass formation of selected lunar compositions.

    Science.gov (United States)

    Scherer, G.; Hopper, R. W.; Uhlmann, D. R.

    1972-01-01

    The kinetics of crystal growth have been determined over a wide range of temperature, from 800 to 1219 C, for lunar compositions 14259 and 14310. At all temperatures for both compositions the extent of crystal growth is found to be a linear function of time. For both materials, the growth rate versus temperature relations exhibit the form generally found with glass-forming materials. At all temperatures measured, the crystal growth rate of composition 14259 is smaller than that of composition 14310. The maximum growth rate for both compositions occurs at a temperature of about 1120 C. The growth rate data are combined with viscosity data obtained on the same compositions to construct the reduced growth rate versus undercooling relations.

  14. America on Film: A Humanities Composition Course.

    Science.gov (United States)

    Recchia, Edward

    This paper argues that film courses are useful because they sensitize students both to the artistic qualities of film expression and to equivalent qualities in other forms of expression. The objectives of a film course at Michigan State University are: to develop the students' knowledge of the film medium and through that knowledge develop a…

  15. Composition and crystalline properties of TiNi thin films prepared by pulsed laser deposition under vacuum and in ambient Ar gas.

    Science.gov (United States)

    Cha, Jeong Ok; Nam, Tae Hyun; Alghusun, Mohammad; Ahn, Jeung Sun

    2012-01-05

    TiNi shape memory alloy thin films were deposited using the pulsed laser deposition under vacuum and in an ambient Ar gas. Our main purpose is to investigate the influences of ambient Ar gas on the composition and the crystallization temperature of TiNi thin films. The deposited films were characterized by energy-dispersive X-ray spectrometry, a surface profiler, and X-ray diffraction at room temperature. In the case of TiNi thin films deposited in an ambient Ar gas, the compositions of the films were found to be very close to the composition of target when the substrate was placed at the shock front. The in-situ crystallization temperature (ca. 400°C) of the TiNi film prepared at the shock front in an ambient Ar gas was found to be lowered by ca. 100°C in comparison with that of a TiNi film prepared under vacuum.

  16. Refractive indices of polymer-dispersed liquid-crystal film materials: Epoxy-based systems

    Science.gov (United States)

    Vaz, Nuno A.; Montgomery, G. Paul, Jr.

    1987-10-01

    Polymer-dispersed liquid crystal (PDLC) films are potentially useful in applications requiring electrically controllable light transmission. In these applications, both a high on-state transmittance and a strong off-state attenuation are often needed over a wide operating temperature range. These transmittance characteristics depend strongly on the refractive indices of the materials in the PDLC films. We have measured the temperature dependent refractive indices of typical PDLC film materials and the temperature dependent electro-optic transmittance of a PDLC film composed of liquid crystal microdroplets dispersed in an epoxy matrix. We show that our refractive index measurements can account for all the features in the measured transmittance characteristics and discuss several methods for controlling refractive indices to optimize electro-optic transmittance over an extended temperature range. We have also measured the room temperature refractive indices of mixtures of epoxy resins and hardeners as a function of composition. We discuss the problems associated with predicting the refractive indices of such mixtures in terms of either the volume fractions or mole fractions of the mixture components. These considerations are important in matching refractive indices of droplets and matrix materials to maximize on-state transmittance. The refractive indices of epoxy matrix materials increase monotonically with time during their chemical cure. The measured time dependence can be described by a simple model in which the concentrations of the reacting resin and hardener each decay exponentially in time with their own characteristic time constants while the concentration of the cured polymer increases. Finally, we relate the measured rates of index change with temperature to the coefficients of volume expansion of PDLC film materials; the results are used to discuss the mechanical stability of PDLC films.

  17. Composition and microstructure of beryllium carbide films prepared by thermal MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    He, Yu-dan; Luo, Jiang-shan; Li, Jia; Meng, Ling-biao; Luo, Bing-chi; Zhang, Ji-qiang; Zeng, Yong; Wu, Wei-dong, E-mail: wuweidongding@163.com

    2016-02-15

    Highlights: • Non-columnar-crystal Be{sub 2}C films were firstly prepared by thermal MOCVD. • Beryllium carbide was always the dominant phase in the films. • α-Be and carbon existed in films deposited below and beyond 400 °C, respectively. • Morphology evolved with temperatures and no columnar grains were characterized. • The preferred substrate temperature for depositing high quality Be{sub 2}C films was 400 °C. - Abstract: Beryllium carbide films without columnar-crystal microstructures were prepared on the Si (1 0 0) substrate by thermal metal organic chemical vapor deposition using diethylberyllium as precursor. The influence of the substrate temperature on composition and microstructure of beryllium carbide films was systematically studied. Crystalline beryllium carbide is always the dominant phase according to XRD analysis. Meanwhile, a small amount of α-Be phase exists in films when the substrate temperature is below 400 °C, and hydrocarbon or amorphous carbon exists when the temperature is beyond 400 °C. Surfaces morphology shows transition from domes to cylinders, to humps, and to tetraquetrous crystalline needles with the increase of substrate temperature. No columnar grains are characterized throughout the thickness as revealed from the cross-section views. The average densities of these films are determined to be 2.04–2.17 g/cm{sup 3}. The findings indicate the substrate temperature has great influences on the composition and microstructure of the Be{sub 2}C films grown by thermal MOCVD.

  18. Structures and growth mechanisms of poly-(3-hydroxybutyrate) (PHB) crystallized from solution and thin melt film

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The spherulitic structures and morphologies of poly-(3-hydroxybutyrate) (PHB) crystallized from a so- lution and a thin melt film were investigated in this study. The formation mechanisms of banded spherulites under different crystallization conditions are proposed. It was found that the formation of banded spherulites was caused by the rhythmic crystal growth of the spherulites and lamellar twisting growth for the polymer crystallization from a thin melt film and a solution, respectively.

  19. Mesoporous multilayer thin films: environment-sensitive photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Soler Illia, Galo; Fuertes, Maria Cecilia; Angelome, Paula Cecilia [Comision Nacional de Energia Atomica, San Martin, Buenos Aires (Argentina). Centro Atomico Constituyentes. Gerencia de Quimica; Marchi, Maria Claudia [Universidad de Buenos Aires (Argentina). Facultad de Ciencias Exactas y Naturales. INQUIMAE; Troiani, Horacio [Comision Nacional de Energia Atomica (CNEA), San Carlos de Bariloche (Argentina). Centro Atomico Bariloche and Instituto Balseiro; Luca, Vittorio [Australian Nuclear Science and Technology Organization, Lucas Heights (Australia). Inst. of Materials and Engineering Sciences; Miguez, Hernan [Consejo Superior de Investigaciones Cientificas, Isla de La Cartuja, Sevilla (Spain). Inst. de Ciencia de Materiales

    2008-11-15

    Photonic Crystals made up of stacked mesoporous thin films (MTF) were produced by sequential deposition. These materials present order at different length scales: atomic (local structure), mesoscopic (ordered mesopores) and submicronic (controlled thickness), which were accurately assessed by Small Angle X-ray Scattering (2D SAXS, D11A SAXS1) and X-ray Reflectometry (XRR, D10A XRD2). Each MTF building block of a complex multilayer architecture behaves like an 'optical switch' in the presence of vapours. Its electronic density (and therefore the refractive index) changes due to capillary condensation of a given solvent within the pore systems. This allows for the creation of photonic crystals that are responsive to environment, with promising applications in selective sensing or active waveguides. (author)

  20. Crystallization kinetics of poly(lactic acid-talc composites

    Directory of Open Access Journals (Sweden)

    2011-10-01

    Full Text Available The crystallization kinetics of poly(lactic acid / talc composites were determined over a range of 0 to 15 wt% of talc. Talc was found to change the crystallization kinetics. The presence of talc increases the crystallization rate and this increase is related to talc concentration and to crystallization temperature. In order to understand the effect of talc and PLA crystallinity on mechanical properties, dynamic mechanical thermal analyses were performed on poly(lactic acid / talc composites before and after an annealing process. It was demonstrated that the presence of crystals improves thermomechanical properties but in order to achieve good results at high temperatures the reinforcing effect of a filler such as talc is necessary.

  1. Nanocrystallization of amorphous M-Si thin film composites (M=Cr, Mn) and their thermoelectric properties

    Science.gov (United States)

    Burkov, A. T.; Novikov, S. V.; Schumann, J.

    2012-06-01

    We report on electrical resistivity and thermoelectric power of Cr-Si and Mn-Si composite films at temperatures from 300 K to 1000 K. The films were deposited on unheated Si/SiO2 substrates by magnetron sputtering from composite targets. The as-deposited films have amorphous structure. We use annealing with in-situ transport properties measurements to transform the films into nanocrystalline state with continuous monitoring their state. Nanocrystallization is considered as a promising way to improve thermoelectric efficiency, primarily due to reduction of lattice thermal conductivity κ. Among variety of methods for fabrication of NC materials, crystallization from amorphous state has features which are crucially important with respect to their electronic transport properties: since the crystallites and their interfaces are formed in this method via solid state reaction, the NC samples are dense and the interfaces are clean. This removes additional factors affecting properties of a nanocrystalline composite, such as contamination of nanocrystal interfaces by elements from environment or nanocrystal lattice distortion during nanocrystallization. Depending on the initial film composition, the films are transformed during annealing into single phase or multi-phase nanocrystalline composites with average grain size of 10 nm to 20 nm. We study the crystallization kinetics, stability of amorphous and nanocrystalline state and relation between electronic transport properties and structural state of the composites.

  2. Compositional Segregation in Unidirectionally Solidified Solid Solution Crystals

    Science.gov (United States)

    Wang, J. C.

    1983-01-01

    A computer program was developed to model compositional segregation in unidrectionally solidified solid-solution-semiconducting crystals. The program takes into account the variations of the interface segregation constant and solidification rate with composition. Calculations are performed for the HgCdTe solid solution system that is compared with experimental data.

  3. Grain Size and Wettability of TiO2/SiO2 Photocatalytic Composite Thin Films

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that the addition of SiO2 to TiO2 thin films can suppress the grain growth of TiO2 crystal, increase the hydroxyl content on the surface of TiO2 films, lower the contact angle for water on TiO2 films and enhance the hydrophilic property of TiO2 films. The super-hydrophilic TiO2/SiO2 photocatalytic composite thin films with the contact angle of 0-° are obtained by the addition of 10%-20% SiO2 in mole fraction.

  4. Tribological performances of diamond film and graphite/diamond composite film with paraffin oil lubrication

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, the tribological performances of diamond film and graphite/diamond com-posite film were compared on an SRV wear testing machine with paraffin oil lubrication. The sur-face morphologies of specimens and wear tracks were observed by SEM. The wear volumes ofwear tracks were measured by profilometer. The influence of load on the tribological performancesof different specimens was studied. The wear mechanism under paraffin oil lubrication was ana-lyzed. The results showed that with paraffin oil lubrication, the friction coefficient and wear volumeof graphite/diamond composite film specimen are lower than diamond film. Under paraffin oil lu-brication, the wear mechanisms of both diamond film and graphite/diamond composite film weremainly sub-micro-fracture.

  5. Direct Electrochemistry of Myoglobin in DDAB-Clay Composite Films

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Ordered films were made by casting a mixture of aqueous dispersions of didodecyldimethylammonium bromide (DDAB)-clay composite and myoglobin (Mb) solution on pyrolytic graphite (PG) electrodes.The Mb-DDAB-clay film electrodes showed stable and reversible cyclic voltammetric responses in buffers and can catalyze the reduction of trichloroacetic acid (TCA).

  6. Determination and observation of electronic defect levels in CuInSe sub 2 crystals and thin films

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Elfotouh, F.A.; Kazmerski, L.L.; Moutinho, H.R.; Wissel, J.M.; Dhere, R.G.; Nelson, A.J.; Bakry, A.M. (Solar Energy Research Institute, Golden, Colorado 80401 (US))

    1991-05-01

    The effects of heat and surface treatments used in the fabrication of CuInSe{sub 2} (CIS) single-crystal and thin-film solar cells are investigated, and the associated dominant defect states are identified using high-resolution photoluminescence (PL) and deep-level transient spectroscopy (DLTS) measurements. The results are correlated with junction electrical characteristics, and comparisons between thin films and single crystals are established. For the first time, direct evidence for several major defect types (Cu vacancies, Cu at In sites, and In at Cu sites) responsible for the majority-carrier type of the CIS is presented based upon spectroscopic atomic imaging of the {ital n}- and {ital p}-type semiconductor surfaces. Radiative recombination levels of extrinsic origin resulting from the surface processing (including polishing, etching, and annealing) were detected in the near surface region of the CIS single crystals, but not in the thin-film material having the same composition. The energy locations and depth of these states are responsible for the formation of an interfacial layer that is confirmed from frequency-dependent capacitance--voltage ({ital C}--{ital V}) data. The DLTS measurements on single-crystal and thin-film heterostructure {l brace}i.e., (Cd,Zn)S/CIS{r brace} devices (of nearly identical chemical compositions) have also confirmed the presence of a dominant trap level in the 270-meV region above the valance band. However, the trap density is some two orders of magnitude lower in the thin-film device, giving evidence that this processing-related defect level is responsible for the inferior performance of the single-crystal solar cells.

  7. Microstructural and Mechanical Studies of PVA Doped with ZnO and WO3 Composites Films

    Directory of Open Access Journals (Sweden)

    N. B. Rithin Kumar

    2014-01-01

    Full Text Available Polymer composites of ZnO and WO3 nanoparticles doped polyvinyl alcohol (PVA matrix have been prepared using solvent casting method. The microstructural properties of prepared films were studied using FTIR, XRD, SEM, and EDAX techniques. In the doped PVA, many irregular shifts in the FTIR spectra have been observed and these shifts in bands can be understood on the basis of intra/intermolecular hydrogen bonding with the adjacent OH group of PVA. The chemical composition, phase homogeneity, and morphology of the polymer composites of the polymer film were studied using EDAX and SEM. These data indicate that the distribution of nanosized ZnO and WO3 dopants is uniform and confirm the presence of ZnO and WO3 in the film. The crystal structure and crystallinity of polymer composites were studied by XRD. It was found that the change in structural repositioning and crystallinity of the composites takes place due to the interaction of dopants and also due to complex formation. The mechanical studies of doped polymer films were carried out using universal testing machine (UTM at room temperature, indicating that the addition of the ZnO and WO3 with weight percentage concentration equal to 14% increases the tensile strength and Young’s modulus.

  8. Preparation of sensitive and recyclable porous Ag/TiO2 composite films for SERS detection

    Science.gov (United States)

    Zhang, Zhengyi; Yu, Jiajie; Yang, Jingying; Lv, Xiang; Wang, Tianhe

    2015-12-01

    Porous Ag/TiO2 composite films were prepared by spin coating of titania on normal glass slides and subsequent photochemical deposition of silver nanoparticles (AgNPs). The films were characterized by XRD and FESEM to reveal micro structural and morphological differences between films obtained under varied conditions. The SERS properties of these films were investigated using aqueous crystal violet (CV) as probe molecules. The results indicate that the content of polyethylene glycol (PEG) and photo-reduction time had significant influences on both the microstructure and SERS performance of Ag/TiO2 films. The highest SERS sensitivity that allowed as low as 10-10 M aqueous CV to be detected, was achieved with the PEG/(C4H9O)4Ti molar ratio being 0.08% and with 30 min of UV irradiation. With this film a linear relationship was established through experiment between SERS intensity and CV concentration from 10-10 to 10-5 M, which could be used as a calibration curve for CV concentration measurement. In addition, the film could be reused as a SERS substrate for up to four times without significantly losing SERS sensitivity if a simple regeneration was followed. It is visualized that the Ag/TiO2 film on glass has potentials for being developed into a practical SERS substrate with high sensitivity and good reusability.

  9. The Impact of the Crystallization Processes on the Structural and Optical Properties of Hybrid Perovskite Films for Photovoltaics.

    Science.gov (United States)

    Grancini, Giulia; Marras, Sergio; Prato, Mirko; Giannini, Cinzia; Quarti, Claudio; De Angelis, Filippo; De Bastiani, Michele; Eperon, Giles E; Snaith, Henry J; Manna, Liberato; Petrozza, Annamaria

    2014-11-06

    We investigate the relationship between structural and optical properties of organo-lead mixed halide perovskite films as a function of the crystallization mechanism. For methylammonium lead tri-iodide, the organic cations rearrange within the inorganic cage, moving from crystals grown in a mesoporous scaffold to larger, oriented crystals grown on a flat substrate. This reduces the strain felt by the bonds forming the cage and affects the motion of the organic cation in it, influencing the electronic transition at the onset of the optical absorption spectrum of the semiconductor. Moreover, we demonstrate that in mixed-halide perovskite, though Cl(-) ions are not present in a detectable concentration in the unit cell, they drive the crystallization dynamics. This induces a preferential order during crystallization, from a molecular, i.e., organic-inorganic moieties arrangement, to a nano-mesoscopic level, i.e., larger crystals with anisotropic shape. Finally, we show that while Cl is mainly expelled from flat films made of large crystals, in the presence of an oxide mesoporous scaffold they are partially retained in the composite.

  10. Film-Making and Teaching Composition.

    Science.gov (United States)

    Lycette, Ronald L.

    1970-01-01

    To stimulate students to learn through creative participation and to make literature a live experience, an experimental film making project was conducted with freshmen at Bimidji State College during the 1969-70 term. The first step was to introduce film-making to the students. This was accomplished through viewing and analyzing brief…

  11. Drug release kinetics from carboxymethylcellulose-bacterial cellulose composite films.

    Science.gov (United States)

    Juncu, Gheorghe; Stoica-Guzun, Anicuta; Stroescu, Marta; Isopencu, Gabriela; Jinga, Sorin Ion

    2016-08-30

    Composite films of sodium carboxymethyl cellulose and bacterial cellulose (NaCMC-BC) cross-linked with citric acid (CA) were prepared by solution casting method. Ibuprofen sodium salt (IbuNa) has been used to study the mechanism of drug release from composite films. Surface morphology was investigated by scanning electron microscopy (SEM) and proved that the BC content influences the aspect of the films. Fourier transformed infrared spectroscopy (FTIR) revealed specific peaks in IR spectra of composite films which sustain that NaCMC was cross-linked with CA. Starting from swelling observations, the release kinetic of IbuNa was described using a model which neglects the volume expansion due to polymer swelling and which considers non-linear diffusion coefficients for drug and solvent. The IbuNa release is also influenced by BC content, the drug release rate was decreasing with the increase of BC content.

  12. Large Area Single Crystal (0001) Oriented MoS2 Thin Films

    OpenAIRE

    Laskar, Masihhur R.; Ma, Lu; K, ShanthaKumar; Park, Pil Sung; Krishnamoorthy, Sriram; Nath, Digbijoy N.; Lu, Wu; Wu, Yiying; Rajan, Siddharth

    2013-01-01

    Layered metal dichalcogenide materials are a family of semiconductors with a wide range of energy band gaps and properties, and potential to open up new areas of physics and technology applications. However, obtaining high crystal quality thin films over a large area remains a challenge. Here we show that chemical vapor deposition (CVD) can be used to achieve large area electronic grade single crystal Molybdenum Disulfide (MoS2) thin films with the highest mobility reported in CVD grown films...

  13. Selective scattering polymer dispersed liquid crystal film for light enhancement of organic light emitting diode.

    Science.gov (United States)

    Jiang, Jinghua; McGraw, Greg; Ma, Ruiqing; Brown, Julie; Yang, Deng-Ke

    2017-02-20

    We developed a novel light enhancing film for an organic light emitting diode (OLED) based on polymer dispersed liquid crystal (PDLC). In the film, the liquid crystal droplets are unidirectionally aligned along the film normal direction and exhibit selective scattering. The film scatters light emitted only in directions with large incident angles but not light emitted in directions with small incident angles. When the light is scattered, it changes propagation direction and exits the OLED. The PDLC film reduces the total internal reflection and thus can significantly increase the light efficiency of the OLED.

  14. Fabrication and structure of Langmuir-Blodgett films of ferroelectric liquid crystal

    Institute of Scientific and Technical Information of China (English)

    WEN Zi; JIANG Qing; T.Kenji; O.Yukihiro

    2005-01-01

    The molecular aggregation, orientation, and structure in Langmuir-Blodgett films of ferroelectric liquid crystal were studied by ultraviolet and Fourier transform infrared spectra. The results show that medium strong H-aggregates in the Langmuir-Blodgett films of ferroelectric liquid crystal are formed by chromophores where the alkyl chains are nearly perpendicular to the film surface. Compared with the cast films, the CO stretching bands, due to the rotational isomerism around the O-C axis of the chiral part, can be identified clearly in Langmuir-Blodgett films.

  15. Single crystal piezoelectric composites for advanced NDT ultrasound

    Science.gov (United States)

    Jiang, Xiaoning; Snook, Kevin; Hackenberger, Wesley S.; Geng, Xuecang

    2007-04-01

    In this paper, the design, fabrication and characterization of PMN-PT single crystal/epoxy composites are reported for NDT ultrasound transducers. Specifically, 1-3 PMN-PT/epoxy composites with center frequencies of 5 MHz - 40 MHz were designed and fabricated using either the dice-and-fill method or a photolithography based micromachining process. The measured electromechanical coefficients for composites with frequency of 5 MHz - 15 MHz were about 0.78-0.83, and the coupling coefficients for composites with frequencies of 25 MHz- 40 MHz were about 0.71-0.72. The dielectric loss remains low (advanced NDT ultrasound applications.

  16. In situ X-ray diffraction based investigation of crystallization in solution deposited PZT thin films

    Science.gov (United States)

    Nittala, Krishna

    Solution deposited PZT based thin films have potential applications in embedded decoupling capacitors and pulse discharge capacitors. During solution deposition, precursor solution is deposited onto a substrate to obtain an amorphous film. The film is then crystallized by heating it at a high temperature (˜600 - 700°C). Conditions during the crystallization anneal such as precursor stoichiometry in solution, heating rate and adhesion layer in the substrate are known to influence phase and texture evolution in these films. However, a mechanistic understanding of the changes taking place in these thin films during crystallization is lacking. A better understanding of the crystallization processes in these thin films could enable tailoring the properties of thin films to suit specific applications. To explore the crystallization process in solution deposited PZT thin films, high temperature in situ laboratory and synchrotron X-ray diffraction based techniques were developed. Taking advantage of the high X-ray flux available at synchrotron facilities such as beamline 6-ID-B, Advanced Photon Source, Argonne National Laboratory, crystalline phases formed in the thin films during crystallization at the high heating rates (0.5 -- 60°C/s) typically used during film processing could be measured. Using a 2-D detector for these measurements allowed the simultaneous measurement of both phase and texture information during crystallization. Analytical treatment of the unconventional diffraction geometry used during the synchrotron based measurements was performed to develop methodologies for quantitative estimation of texture components. The nominal lead content in the starting solutions and the heating rate used during crystallization was observed to influence the sequence of phases formed during crystallization of the films. In films crystallized at fast heating rates, titanium segregation, probably due to diffusion of titanium from the adhesion layer, was observed. To

  17. Composition and morphological characteristics of chemically sprayed fluorine-doped zinc oxide thin films deposited on Si(1 0 0)

    Energy Technology Data Exchange (ETDEWEB)

    Castaneda, L. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, 04510 D. F. (Mexico); Departamento de Fisica y Matematicas, Division de Ciencia, Arte y Tecnologia, Universidad Iberoamericana, Av. Prolongacion Paseo de la Reforma 880, Santa Fe 012100, D. F. (Mexico); Maldonado, A. [Depto. de Ing. Electrica, CINVESTAV IPN, SEES, Apartado Postal 14740, Mexico, D.F. 07000 (Mexico); Cheang-Wong, J.C. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Mexico, D.F. 01000 (Mexico); Terrones, M. [Advanced Materials Department, IPICYT, Camino a la Presa San Jose 2055, Col. Lomas, 4a. seccion, San Luis Potosi, 78216 (Mexico); Departamento de Fisica y Matematicas, Division de Ciencia, Arte y Tecnologia, Universidad Iberoamericana, Av. Prolongacion Paseo de la Reforma 880, Santa Fe 012100, D. F. (Mexico); Olvera, M. de la L [Depto. de Ing. Electrica, CINVESTAV IPN, SEES, Apartado Postal 14740, Mexico, D.F. 07000 (Mexico)]. E-mail: molvera@cinvestav.mx

    2007-03-01

    Fluorine-doped zinc oxide thin films (ZnO:F) were deposited on Si(1 0 0) substrates by the chemical spray technique (CST) from an aged-solution. The effect of the substrate temperature on the morphology and composition of the ZnO:F thin films was studied. The films were polycrystalline, with a preferential growth along the ZnO (0 0 2) plane, irrespective of the deposition temperature. The average crystal size within the films was ca. 35 nm and the morphology of the surface was found to be dependent on the substrate temperature. At low substrate temperatures irregular-shaped grains were observed, whereas at higher temperatures uniform flat grains were obtained. Elemental analysis showed that the composition of the films is close to stoichiometric ZnO and that samples contain quite a low fluorine concentration, which decreases as a function of the deposition temperature.

  18. Temperature-controlled transparent-film heater based on silver nanowire-PMMA composite film.

    Science.gov (United States)

    He, Xin; Liu, A'lei; Hu, Xuyang; Song, Mingxia; Duan, Feng; Lan, Qiuming; Xiao, Jundong; Liu, Junyan; Zhang, Mei; Chen, Yeqing; Zeng, Qingguang

    2016-11-25

    We fabricated a high-performance film heater based on a silver nanowire and polymethyl methacrylate (Ag NW-PMMA) composite film, which was synthesized with the assistance of mechanical lamination and an in situ transfer method. The films exhibit excellent conductivity, high figure of merit, and strong adhesion of percolation network to substrate. By controlling NW density, we prepared the films with a transmittance of 44.9-85.0% at 550 nm and a sheet resistance of 0.13-1.40 Ω sq(-1). A stable temperature ranging from 130 °C-40 °C was generated at 3.0 V within 10-30 s, indicating that the resulting film heaters show a rapid thermal response, low driving voltage and stable temperature recoverability. Furthermore, we demonstrated the applications of the film heater in defrosting and a physical therapeutic instrument. A fast defrosting on the composite film with a transmittance of 88% was observed by applying a 9 V driving voltage for 20 s. Meanwhile, we developed a physical therapeutic instrument with two modes of thermotherapy and electronic-pulse massage by using the composite films as two electrodes, greatly decreasing the weight and power consumption compared to a traditional instrument. Therefore, Ag NW-PMMA film can be a promising candidate for diversified heating applications.

  19. Temperature-controlled transparent-film heater based on silver nanowire-PMMA composite film

    Science.gov (United States)

    He, Xin; Liu, A.'lei; Hu, Xuyang; Song, Mingxia; Duan, Feng; Lan, Qiuming; Xiao, Jundong; Liu, Junyan; Zhang, Mei; Chen, Yeqing; Zeng, Qingguang

    2016-11-01

    We fabricated a high-performance film heater based on a silver nanowire and polymethyl methacrylate (Ag NW-PMMA) composite film, which was synthesized with the assistance of mechanical lamination and an in situ transfer method. The films exhibit excellent conductivity, high figure of merit, and strong adhesion of percolation network to substrate. By controlling NW density, we prepared the films with a transmittance of 44.9-85.0% at 550 nm and a sheet resistance of 0.13-1.40 Ω sq-1. A stable temperature ranging from 130 °C-40 °C was generated at 3.0 V within 10-30 s, indicating that the resulting film heaters show a rapid thermal response, low driving voltage and stable temperature recoverability. Furthermore, we demonstrated the applications of the film heater in defrosting and a physical therapeutic instrument. A fast defrosting on the composite film with a transmittance of 88% was observed by applying a 9 V driving voltage for 20 s. Meanwhile, we developed a physical therapeutic instrument with two modes of thermotherapy and electronic-pulse massage by using the composite films as two electrodes, greatly decreasing the weight and power consumption compared to a traditional instrument. Therefore, Ag NW-PMMA film can be a promising candidate for diversified heating applications.

  20. Thin Film Polymer Composite Scintillators for Thermal Neutron Detection

    Directory of Open Access Journals (Sweden)

    Andrew N. Mabe

    2013-01-01

    Full Text Available Thin film polystyrene composite scintillators containing LiF6 and organic fluors have been fabricated and tested as thermal neutron detectors. Varying fluorescence emission intensities for different compositions are interpreted in terms of the Beer-Lambert law and indicate that the sensitivity of fluorescent sensors can be improved by incorporating transparent particles with refractive index different than that of the polymer matrix. Compositions and thicknesses were varied to optimize the fluorescence and thermal neutron response and to reduce gamma-ray sensitivity. Neutron detection efficiency and neutron/gamma-ray discrimination are reported herein as functions of composition and thickness. Gamma-ray sensitivity is affected largely by changing thickness and unaffected by the amount of LiF6 in the film. The best neutron/gamma-ray discrimination characteristics are obtained for film thicknesses in the range 25–150 μm.

  1. Thermally induced crystallization in NbO2 thin films

    Science.gov (United States)

    Zhang, Jiaming; Norris, Kate J.; Gibson, Gary; Zhao, Dongxue; Samuels, Katy; Zhang, Minxian Max; Yang, J. Joshua; Park, Joonsuk; Sinclair, Robert; Jeon, Yoocharn; Li, Zhiyong; Williams, R. Stanley

    2016-09-01

    Niobium dioxide can exhibit negative differential resistance (NDR) in metal-insulator-metal (MIM) devices, which has recently attracted significant interest for its potential applications as a highly non-linear selector element in emerging nonvolatile memory (NVM) and as a locally-active element in neuromorphic circuits. In order to further understand the processing of this material system, we studied the effect of thermal annealing on a 15 nm thick NbO2 thin film sandwiched inside a nanoscale MIM device and compared it with 180 nm thick blanket NbOx (x = 2 and 2.5) films deposited on a silicon dioxide surface as references. A systematic transmission electron microscope (TEM) study revealed a similar structural transition from amorphous to a distorted rutile structure in both cases, with a transition temperature of 700 °C for the NbO2 inside the MIM device and a slightly higher transition temperature of 750 °C for the reference NbO2 film. Quantitative composition analysis from electron energy loss spectroscopy (EELS) showed the stoichiometry of the nominal 15 nm NbO2 layer in the as-fabricated MIM device deviated from the target 1:2 ratio because of an interaction with the electrode materials, which was more prominent at elevated annealing temperature.

  2. Thermally induced crystallization in NbO2 thin films

    Science.gov (United States)

    Zhang, Jiaming; Norris, Kate J.; Gibson, Gary; Zhao, Dongxue; Samuels, Katy; Zhang, Minxian Max; Yang, J. Joshua; Park, Joonsuk; Sinclair, Robert; Jeon, Yoocharn; Li, Zhiyong; Williams, R. Stanley

    2016-01-01

    Niobium dioxide can exhibit negative differential resistance (NDR) in metal-insulator-metal (MIM) devices, which has recently attracted significant interest for its potential applications as a highly non-linear selector element in emerging nonvolatile memory (NVM) and as a locally-active element in neuromorphic circuits. In order to further understand the processing of this material system, we studied the effect of thermal annealing on a 15 nm thick NbO2 thin film sandwiched inside a nanoscale MIM device and compared it with 180 nm thick blanket NbOx (x = 2 and 2.5) films deposited on a silicon dioxide surface as references. A systematic transmission electron microscope (TEM) study revealed a similar structural transition from amorphous to a distorted rutile structure in both cases, with a transition temperature of 700 °C for the NbO2 inside the MIM device and a slightly higher transition temperature of 750 °C for the reference NbO2 film. Quantitative composition analysis from electron energy loss spectroscopy (EELS) showed the stoichiometry of the nominal 15 nm NbO2 layer in the as-fabricated MIM device deviated from the target 1:2 ratio because of an interaction with the electrode materials, which was more prominent at elevated annealing temperature. PMID:27682633

  3. Effect of a Polymercaptan Material on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films

    Directory of Open Access Journals (Sweden)

    Yujian Sun

    2016-12-01

    Full Text Available Polymer-dispersed liquid crystal (PDLC films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found that the weight ratio among acrylate monomers, thiol monomer PETMP and the polymercaptan Capcure 3-800 showed great influence on the properties of the fabricated PDLC films because of the existence of competition between thiol-acrylate reaction and acrylate monomer polymerization reaction. While adding polymercaptans curing agent Capcure 3-800 with appropriate concentration into the PDLC system, lower driven voltage and higher contrast ratio were achieved. This made the polymer network and electro-optical properties of the PDLC films easily tunable by the introduction of the thiol monomers.

  4. Preparation and properties of cellulose nanocrystals reinforced collagen composite films.

    Science.gov (United States)

    Li, Weichang; Guo, Rui; Lan, Yong; Zhang, Yi; Xue, Wei; Zhang, Yuanming

    2014-04-01

    Collagen films have been widely used in the field of biomedical engineering. However, the poor mechanical properties of collagen have limited its application. Here, rod-like cellulose nanocrystals (CNCs) were fabricated and used to reinforce collagen films. A series of collagen/CNCs films were prepared by collagen solution with CNCs suspensions homogeneously dispersed at CNCs: collagen weight ratios of 1, 3, 5, 7, and 10. The morphology of the resulting films was analyzed by scanning electron microscopy (SEM), the enhancement of the thermomechanical properties of the collagen/CNCs composites were demonstrated by thermal gravimetric analysis (TGA) and mechanical testing. Among the CNCs contents used, a loading of 7 wt % led to the maximum mechanical properties for the collagen/CNCs composite films. In addition, in vitro cell culture studies revealed that the CNCs have no negative effect on the cell morphology, viability, and proliferation and possess good biocompatibility. We conclude that the incorporation of CNCs is a simple and promising way to reinforce collagen films without impairing biocompatibility. This study demonstrates that the composite films show good potential for use in the field of skin tissue engineering.

  5. Hydrodynamic interactions in freely suspended liquid crystal films

    Science.gov (United States)

    Kuriabova, Tatiana; Powers, Thomas R.; Qi, Zhiyuan; Goldfain, Aaron; Park, Cheol Soo; Glaser, Matthew A.; Maclennan, Joseph E.; Clark, Noel A.

    2016-11-01

    Hydrodynamic interactions play an important role in biological processes in cellular membranes, a large separation of length scales often allowing such membranes to be treated as continuous, two-dimensional (2D) fluids. We study experimentally and theoretically the hydrodynamic interaction of pairs of inclusions in two-dimensional, fluid smectic liquid crystal films suspended in air. Such smectic membranes are ideal systems for performing controlled experiments as they are mechanically stable, of highly uniform structure, and have well-defined, variable thickness, enabling experimental investigation of the crossover from 2D to 3D hydrodynamics. Our theoretical model generalizes the Levine-MacKintosh theory of point-force response functions and uses a boundary-element approach to calculate the mobility matrix for inclusions of finite extent. We describe in detail the theoretical and computational approach previously outlined in Z. Qi et al., Phys. Rev. Lett. 113, 128304 (2014), 10.1103/PhysRevLett.113.128304 and extend the method to study the mutual mobilities of inclusions with asymmetric shapes. The model predicts well the observed mutual mobilities of pairs of circular inclusions in films and the self-mobility of a circular inclusion in the vicinity of a linear boundary.

  6. Materials research at Stanford University. [composite materials, crystal structure, acoustics

    Science.gov (United States)

    1975-01-01

    Research activity related to the science of materials is described. The following areas are included: elastic and thermal properties of composite materials, acoustic waves and devices, amorphous materials, crystal structure, synthesis of metal-metal bonds, interactions of solids with solutions, electrochemistry, fatigue damage, superconductivity and molecular physics and phase transition kinetics.

  7. On crystallization of bisphenol-A polycarbonate thin films upon annealing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chunhong; Li, Qichao; Mao, Wenfeng; Wang, Peng; He, Chunqing, E-mail: hecq@whu.edu.cn

    2015-10-16

    Crystallization of polycarbonate (PC) films as a function of annealing time has been investigated by various methods. A distinct diffraction peak at 17.56°, a sharp decrease of film thickness, an increase of refractive index and branch-type structures on the surface are found merely for the film after crystallization. Interestingly, positron annihilation parameters demonstrate fractional free-volumes in PC films vary significantly not only before crystallization but also at the early stage of annealing, which are not found by other methods. The results show that free-volumes in PC film must be increased remarkably before crystallization, which enables the occurrence of molecule rearrangement. - Highlights: • Fractional free-volume in PC film decreased of early stage of annealing. • Crystallization of PC film on Si substrate occurred after annealed for ∼48 hours. • Fractional free-volume in PC film increased remarkably before crystallization. • Positron diffusion length and S parameter revealed the variation of free volumes.

  8. Photoluminescence properties of ZnSe/SiO2 composite thin films prepared by sol-gel method

    Institute of Scientific and Technical Information of China (English)

    JIANG Hai-qing; CHE Jun; YAO Xi

    2006-01-01

    ZnSe/SiO2 composite thin films was prepared by sol-gel method. XRD results indicate the phase structure of ZnSe particles embedded in ZnSe/SiO2 composite thin films is sphalerite (cubic ZnS). Spectroscopic ellipsometers were used to investigated the dependences of ellipsometric angle with wavelength of ZnSe/SiO2 composite thin films. The optical constant,thickness,porosity and the concentration of ZnSe of ZnSe/SiO2 thin composite films were fitted according to Maxwell-Garnett effective medium theory. The thickness of ZnSe/SiO2 composite thin thin films was also measured through surface profile. The photoluminescence properties of ZnSe/SiO2 thin composite thin films was investigated through fluorescence spectrometer. The photoluminescence results show that the emission peak at 487 nm (2.5 eV) is excited at 395 nm corresponds to the band-to-band emission of sphalerite ZnSe crystal(2.58 eV). The strength free exciton emission and other emission peaks correlating to ZnSe lattice defect were also observed.

  9. Nanomechanics of cellulose crystals and cellulose-based polymer composites

    Science.gov (United States)

    Pakzad, Anahita

    Cellulose-polymer composites have potential applications in aerospace and transportation areas where lightweight materials with high mechanical properties are needed. In addition, these economical and biodegradable composites have been shown to be useful as polymer electrolytes, packaging structures, optoelectronic devices, and medical implants such as wound dressing and bone scaffolds. In spite of the above mentioned advantages and potential applications, due to the difficulties associated with synthesis and processing techniques, application of cellulose crystals (micro and nano sized) for preparation of new composite systems is limited. Cellulose is hydrophilic and polar as opposed to most of common thermoplastics, which are non-polar. This results in complications in addition of cellulose crystals to polymer matrices, and as a result in achieving sufficient dispersion levels, which directly affects the mechanical properties of the composites. As in other composite materials, the properties of cellulose-polymer composites depend on the volume fraction and the properties of individual phases (the reinforcement and the polymer matrix), the dispersion quality of the reinforcement through the matrix and the interaction between CNCs themselves and CNC and the matrix (interphase). In order to develop economical cellulose-polymer composites with superior qualities, the properties of individual cellulose crystals, as well as the effect of dispersion of reinforcements and the interphase on the properties of the final composites should be understood. In this research, the mechanical properties of CNC polymer composites were characterized at the macro and nano scales. A direct correlation was made between: - Dispersion quality and macro-mechanical properties - Nanomechanical properties at the surface and tensile properties - CNC diameter and interphase thickness. Lastly, individual CNCs from different sources were characterized and for the first time size-scale effect on

  10. Crack-free and scalable transfer of carbon nanotube arrays into flexible and highly thermal conductive composite film.

    Science.gov (United States)

    Wang, Miao; Chen, Hongyuan; Lin, Wei; Li, Zhuo; Li, Qiang; Chen, Minghai; Meng, Fancheng; Xing, Yajuan; Yao, Yagang; Wong, Ching-ping; Li, Qingwen

    2014-01-08

    Carbon nanotube (CNT) arrays show great promise in developing anisotropic thermal conductive composites for efficiently dissipating heat from high-power devices along thickness direction. However, CNT arrays are always grown on some substrates and liable to be deformed and broken into pieces during transfer and solution treatment. In the present study, we intentionally synthesized well-crystallized and large-diameter (~80 nm) multiwalled CNT (MWCNT) arrays by floating catalyst chemical vapor deposition (FCCVD) method. Such arrays provided high packing density and robust structure from collapse and crack formation during post solution treatment and therefore favored to maintain original thermal and electrical conductive paths. Under optimized condition, the CNT arrays can be transferred into flexible composite films. Furthermore, the composite film also exhibited excellent thermal conductivity at 8.2 W/(m·K) along thickness direction. Such robust, flexible, and highly thermal conductive composite film may enable some prospective applications in advanced thermal management.

  11. Synthesis of Poly-Silicon Thin Films on Glass Substrate Using Laser Initiated Metal Induced Crystallization of Amorphous Silicon for Space Power Application

    Science.gov (United States)

    Abu-Safe, Husam H.; Naseem, Hameed A.; Brown, William D.

    2007-01-01

    Poly-silicon thin films on glass substrates are synthesized using laser initiated metal induced crystallization of hydrogenated amorphous silicon films. These films can be used to fabricate solar cells on low cost glass and flexible substrates. The process starts by depositing 200 nm amorphous silicon films on the glass substrates. Following this, 200 nm of sputtered aluminum films were deposited on top of the silicon layers. The samples are irradiated with an argon ion cw laser beam for annealing. Laser power densities ranging from 4 to 9 W/cm2 were used in the annealing process. Each area on the sample is irradiated for a different exposure time. Optical microscopy was used to examine any cracks in the films and loss of adhesion to the substrates. X-Ray diffraction patterns from the initial results indicated the crystallization in the films. Scanning electron microscopy shows dendritic growth. The composition analysis of the crystallized films was conducted using Energy Dispersive x-ray Spectroscopy. The results of poly-silicon films synthesis on space qualified flexible substrates such as Kapton are also presented.

  12. Al-induced Lateral Crystallization of Amorphous Si Thin Films by Microwave Annealing

    Institute of Scientific and Technical Information of China (English)

    RAO Rui; XU Zhong-yang; ZENG Xiang-bing

    2002-01-01

    Al-induced lateral crystallization of amorphous silicon thin films by microwave annealing is investigated. The crystallized Si films are examined by optical microscopy , Raman spectroscopy, transmission electron microscopy and transmission electron diffraction micrography. After microwave annealing at 480 ℃ for 50 min,the amorphous Si is completely crystallized with large grains of main ( 111 ) orientation. The rate of lateral crystallization is 0.04μm/min. This process, labeled MILC-MA, not only lowers the temperature but also reduces the time of crystallization. The crystallization mechanism during microwave annealing and the electrical properties of polycrystalline Si thin films are analyzed. This MILC-MA process has potential applications in large area electronics.

  13. Digital Compositing Dalam Film Animasi 3 Dimensi

    Directory of Open Access Journals (Sweden)

    Cito Yasuki Yasuki Rahmad

    2016-01-01

    Full Text Available Animation is a technique mostly used in the film world. Nowadays it is growing intechnical animation creation. Animation has evolved from 2D animation to the nextstage in the new form, more realistic and interesting, that is the 3D animation. With thedevelopment of existing technology, the 3D animation is more amazing for the audience,especially 3D animation combined with real action (live action. With the digitalcompositing, the result of a combination of 3D and real action to make the film seemmore alive, because the animation is really close to the original in real life.

  14. Deterministic aperiodic composite lattice-structured silicon thin films for photon management

    CERN Document Server

    Xavier, Jolly; Becker, Christiane

    2016-01-01

    Exotic manipulation of the flow of photons in nanoengineered semiconductor materials with an aperiodic distribution of nanostructures plays a key role in efficiency-enhanced and industrially viable broadband photonic technologies. Through a generic deterministic nanotechnological route, in addition to periodic, transversely quasicrystallographic or disordered random photonic lattices, here we show scalable nanostructured semiconductor thin films on large area nanoimprinted substrates up to 4cm^2 with advanced functional features of aperiodic composite nanophotonic lattices having tailorable supercell tiles. The richer Fourier spectra of the presented artificially nanostructured materials with well-defined lattice point morphologies are designed functionally akin to two-dimensional incommensurate intergrowth aperiodic lattices-comprising periodic photonic crystals and in-plane quasicrystals as subgroups. The composite photonic lattice-structured crystalline silicon thin films with tapered nanoholes or nanocone...

  15. Sol-gel derived bioactive hydroxyapatite/titania composite films on Ti6Al4V

    Institute of Scientific and Technical Information of China (English)

    Bing Su; Guoqing Zhang; Xudong Yu; Chengtao Wang

    2006-01-01

    The composite films consisting of the titania gel impregnated with hydroxyapatite (HAP) submicron particles were prepared on commercial Ti6Al4V plates processed by a sol-gel route. HAP powders were synthesized based on wet chemical precipitation method with Ca(NO3)2.4H2O and (NH4)2HPO4 as starting reagents. After being calcined at 900℃, HAP powders were ultrasonically scattered in ethanol to produce HAP sol. The titania sol was prepared using titanium (Ⅳ) isopropoxide {Ti[OCH(CH3)2]4} as precursor. Both the titania sol and the HAP/titania mixture were sequentially spin-coated on the substrates and calcined at various temperatures.The characteristics and mechanical adhesion of the composite films were investigated. The results show that the as-prepared films are dense, homogeneous, well-crystallized, and there is a good interfacial adhesion between the film and the substrate. The in vitro bioactivities of these films were discussed based on the analysis of the variations of Ca and P concentrations in the simulated body fluid and their surface morphologies against immersion time.

  16. The effective flux through a thin-film composite membrane

    Science.gov (United States)

    Bruna, M.; Chapman, S. J.; Ramon, G. Z.

    2015-05-01

    Composite membrane structures, used extensively in separation processes, comprise an ultra-thin selective polymer film cast over a porous support, whose pores partially obstruct transport out of the top film. Here, we model the composite as a finite thickness slab with a periodic array of circular absorbing patches in an otherwise reflective surface and study the effective transport properties of the composite. We obtain an analytical approximation for the effective diffusive flux as a function of the geometrical parameters, namely the film thickness, the support porosity and the pore size. We find a good agreement with full numerical solutions, and that a good effective rate is achievable with a relatively small number of pores.

  17. Wearable near-field communication antennas with magnetic composite films

    Science.gov (United States)

    Zhan, Bihong; Su, Dan; Liu, Sheng; Liu, Feng

    2017-06-01

    The flexible near-field communication (NFC) antennas integrated with Fe3O4/ethylene-vinyl acetate copolymer (EVA) magnetic films were presented, and the influence of the magnetic composite films on the performance and miniaturization capability of the NFC antennas was investigated. Theoretical analysis and experimental results show that the integration of the magnetic composite films is conducive to the miniaturization of the NFC antennas. However, the pattern design of the integrated magnetic film is very important to improve the communication performance of NFC antenna. When magnetic film covers whole antenna, the inductance (L) and quality factor (Q) of the NFC antenna at 13MHz are increased by 60% and 5% respectively, but the communication distance of NFC system is decreased by 70%. When the magnetic film is located at the center of the antenna, the L value, Q value and communication distance of the NFC antenna are increased by 16.5%, 15.5% and 20% respectively. It can be seen that the application of the integrated magnetic film with optimized pattern to the NFC antenna can not only reduce the size of the antenna, but also improve the overall performance of the antenna.

  18. Effect of crystalline microstructure on the photophysical performance of polymer/perylene composite films

    Institute of Scientific and Technical Information of China (English)

    FengWei; XuYou-Long; YiWen-Hui; ZhouFeng; WangXiao-Gong; YoshinoKatsumi

    2003-01-01

    To obtain high carrier mobility, better charge injection capability, and high photovoltaic device conversion efficiency a powerful stratergy is to improve the morphology of the polymer/dye composite films. Conjugated conducting polymer (CP) thin films doped with perylene derivative (PV) of various concentrations were prepared by spin-casting method, and their morphology and photovoltaic characteristics were examined. The change in morphology and molecular reorientation occurring in CP-PV composite films upon annealing at different temperatures was investigated using scanning electron microscopy, x-ray diffraction, Fourier transform infrared and UV-vis absorption. By changing the annealing temperature, PV microcrystallines of 8-10μm in size lying parallel to the substrate surface can be obtained. Annealing effect improved the photovoltaic performance of ITO/CP-PV/Al Schottky-type solar cells, which can be attributed to the formation of an electron conducting PV crystal network. Preliminary studies indicate that the morphological structure in CP-PV composite films has an important influence to their photovoltaic properties.

  19. Effect of crystalline microstructure on the photophysical performance of polymer/perylene composite films

    Institute of Scientific and Technical Information of China (English)

    封伟; 徐友龙; 易文辉; 周峰; 王晓工; 吉野勝美

    2003-01-01

    To obtain high carrier mobility, better charge injection capability, and high photovoltaic device conversion efficiency, a powerful strategy is to improve the morphology of the polymer/dye composite films. Conjugated conducting polymer (CP) thin films doped with perylene derivative (PV) of various concentrations were prepared by spin-casting method, and their morphology and photovoltaic characteristics were examined. The change in morphology and molecular reorientation occurring in CP-PV composite films upon annealing at different temperatures was investigated using scanning electron microscopy, x-ray diffraction, Fourier transform infrared and UV-vis absorption. By changing the annealing temperature, PV microcrystallines of 8-10μm in size lying parallel to the substrate surface can be obtained.Annealing effect improved the photovoltaic performance of ITO/CP-PV/A1 Schottky-type solar cells, which can be attributed to the formation of an electron conducting PV crystal network. Preliminary studies indicate that the morphological structure in CP-PV composite films has an important influence to their photovoltaic properties.

  20. PMN-PT-PZT composite films for high frequency ultrasonic transducer applications.

    Science.gov (United States)

    Hsu, Hsiu-Sheng; Benjauthrit, Vatcharee; Zheng, Fan; Chen, Rumin; Huang, Yuhong; Zhou, Qifa; Shung, K Kirk

    2012-06-01

    We have successfully fabricated x(0.65PMN-0.35PT)-(1 - x)PZT (xPMN-PT-(1 - x)PZT), where x is 0.1, 0.3, 0.5, 0.7 and 0.9, thick films with a thickness of approximately 9 µm on platinized silicon substrate by employing a composite sol-gel technique. X-ray diffraction analysis and scanning electron microscopy revealed that these films are dense and creak-free with well-crystallized perovskite phase in the whole composition range. The dielectric constant can be controllably adjusted by using different compositions. Higher PZT content of xPMN-PT-(1 - x)PZT films show better ferroelectric properties. A representative 0.9PMN-PT-0.1PZT thick film transducer is built. It has 200 MHz center frequency with a -6 dB bandwidth of 38% (76 MHz). The measured two-way insertion loss is 65 dB.

  1. Preparation and characterization of Co epitaxial thin films on Al2O3(0001) single-crystal substrates

    Science.gov (United States)

    Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki

    2011-01-01

    Co epitaxial thin films were prepared on Al2O3(0001) single-crystal substrates in a substrate temperature range between 50 and 500 °C by ultra high vacuum molecular beam epitaxy. Effects of substrate temperature on the structure and the magnetic properties of the films were investigated. The films grown at temperatures lower than 150 °C consist of fcc- Co(111) crystal. With increasing the substrate temperature, hcp-Co(0001) crystal coexists with the fcc crystal and the volume ratio of hcp to fcc crystal increases. The films prepared at temperatures higher than 250 °C consist primarily of hcp crystal. The film growth seems to follow island-growth mode. The films consisting primarily of hcp crystal show perpendicular magnetic anisotropy. The domain structure and the magnetization properties are influenced by the magnetocrystalline anisotropy and the shape anisotropy caused by the film surface roughness.

  2. Influence of solvent evaporation rate on crystallization of poly(vinylidene fluoride) thin films

    Indian Academy of Sciences (India)

    K Pramod; R B Gangineni

    2015-08-01

    The processes for obtaining crystalline and smooth poly(vinylidene fluoride) (PVDF) thin films using 2-butanone solvent are explored. The in-situ substrate temperature has been systematically controlled to observe the crystallization process. The in-situ substrate temperature is manipulated to control the rate of evaporation of 2-butanone solvent and is found to have played a vital role in the crystallization of PVDF thin films. Further, X-ray diffraction and Raman microscope were utilized to understand the crystalline phase of PDVF thin films, while atomic force microscopy and scanning electron microscopy have been utilized to investigate the surface morphology and surface roughness of the films.

  3. Femtosecond Laser Crystallization of Boron-doped Amorphous Hydrogenated Silicon Films

    Directory of Open Access Journals (Sweden)

    P.D. Rybalko

    2016-10-01

    Full Text Available Crystallization of amorphous hydrogenated silicon films with femtosecond laser pulses is one of the promising ways to produce nanocrystalline silicon for photovoltaics. The structure of laser treated films is the most important factor determining materials' electric and photoelectric properties. In this work we investigated the effect of femtosecond laser irradiation of boron doped amorphous hydrogenated silicon films with different fluences on crystalline volume fraction and electrical properties of this material. A sharp increase of conductivity and essential decrease of activation energy of conductivity temperature dependences accompany the crystallization process. The results obtained are explained by increase of boron doping efficiency in crystalline phase of modified silicon film.

  4. Electron-Induced Secondary Electron Emission Properties of MgO/Au Composite Thin Film Prepared by Magnetron Sputtering

    Science.gov (United States)

    Li, Jie; Hu, Wenbo; Wei, Qiang; Wu, Shengli; Hua, Xing; Zhang, Jintao

    2016-12-01

    As a type of electron-induced secondary electron emitter, MgO/Au composite thin film was prepared by reactive magnetron sputtering of individual Mg target and Au target, and the effects of key process parameters on its surface morphology and secondary electron emission (SEE) properties were investigated. It is found that to deposit a NiO buffer layer on the substrate is conducive to the subsequent growth of MgO grains owing to the lattice matching. The gold addition can raise the electrical conductivity of MgO film and further suppress the surface charging. However, the gold deposition would interfere with the MgO crystallization and increase the surface roughness of MgO/Au film. Therefore, MgO/Au composite thin film with a NiO buffer layer and proper deposition times of MgO and Au can achieve superior SEE properties due to good MgO crystallization, low surface roughness and reasonable electrical conductivity. The optimized MgO/Au composite thin film has a higher SEE coefficient and a lower 1-h SEE degradation rate under electron beam bombardment in comparison with MgO film.

  5. Circular patterns of calcium oxalate crystals induced by defective Langmuir-Blodgett film

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The injury of the renal epithelial cell membrane can promote the nucleation of nascent crystals, as well as adhesion of crystals on it. It thus accelerates the formation of renal calculi. In this paper, the defective Langmuir-Blodgett(LB)films were used as a model system to simulate the injured renal epithelial cell membrane. The microcosmic structure of the defective LB film and the molecular mechanism of the effect of this film on nucleation, growth, deposited patterns and adhesion of calcium oxalate monohydrate(COM)were investigated. The circular defective domains were formed in dipalmitoylphosphatidylcholine(DPPC)LB film after the film was treated by potassium oxalate. These domains could induce ring-shaped patterns of COM crystals. In comparison, the LB film without pretreatment by potassium oxalate only induced random growth of hexagonal COM crystals. As the crystallization time increased, the size of COM crystals in the patterns increased, the crystal patterns changed from empty circles to solid circles, and the number of the circular patterns with small size(5-20μm)increased. The results would shed light on the molecular mechanism of urolithiasis induced by injury of the renal epithelial membrane at the molecular and supramolecular level.

  6. Circular patterns of calcium oxalate crystals induced by defective Langmuir-Blodgett film

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The injury of the renal epithelial cell membrane can promote the nucleation of nascent crystals, as well as adhesion of crystals on it. It thus accelerates the formation of renal calculi. In this paper, the defective Langmuir-Blodgett (LB) films were used as a model system to simulate the injured renal epithelial cell membrane. The microcosmic structure of the defective LB film and the molecular mechanism of the effect of this film on nucleation, growth, deposited patterns and adhesion of calcium oxalate monohydrate (COM) were investigated. The circular defective domains were formed in dipalmitoylphosphatidylcholine (DPPC) LB film after the film was treated by potassium oxalate. These domains could induce ring-shaped patterns of COM crystals. In comparison, the LB film without pretreatment by potassium oxalate only induced random growth of hexagonal COM crystals. As the crystallization time increased, the size of COM crystals in the patterns increased, the crystal patterns changed from empty circles to solid circles, and the number of the circular patterns with small size (5-20 μm) increased. The results would shed light on the molecular mechanism of urolithiasis induced by injury of the renal epithelial membrane at the molecular and supramolecular level.

  7. In-situ observation of nucleated polymer crystallization in polyoxymethylene sandwich composites

    Directory of Open Access Journals (Sweden)

    Miroslav eSlouf

    2015-03-01

    Full Text Available We introduce a dynamic sandwich method, which can be used for in-situ observation and quantification of polymer crystallization nucleated by micro/nanoparticles. The method was applied on polyoxymethylene (POM composites with three nucleating agents: talc micropowder (POM/mTalc, chalk nanopowder (POM/nChalk and titanate nanotubes (POM/TiNT. The nucleating agents were deposited between polymer films, the resulting sandwich samples were consolidated by thermal treatment, and their microtomed cross-sections were observed during isothermal crystallization by polarized light microscopy. As the intensity of polarized light was shown to be proportional to the relative crystallinity, the PLM results could be fitted to Avrami equation and the nucleating activity of all investigated particles could be quantified by means of Avrami parameters (n, k. The crystallization half-times increased reproducibly in the following order: POM/nChalk < POM/mTalc < POM/TiNT ~ POM. For strong nucleating agents (mTalc, nChalk, the crystallization kinetics corresponded to spontaneous crystallization starting from central nucleating layer, which was verified by computer simulations. The results were also confirmed by DSC. We concluded that the sandwich method is an efficient microscopic technique for detailed evaluation of nucleating activity of arbitrary micro/nanoparticles in polymer systems.

  8. Electrochemical formation of a composite polymer-aluminum oxide film

    Science.gov (United States)

    Runge-Marchese, Jude Mary

    1997-10-01

    The formation of polymer films through electrochemical techniques utilizing electrolytes which include conductive polymer is of great interest to the coatings and electronics industries as a means for creating electrically conductive and corrosion resistant finishes. One of these polymers, polyamino-benzene (polyaniline), has been studied for this purpose for over ten years. This material undergoes an insulator-to-metal transition upon doping with protonic acids in an acid/base type reaction. Review of prior studies dealing with polyaniline and working knowledge of aluminum anodization has led to the development of a unique process whereby composite polymer-aluminum oxide films are formed. The basis for the process is a modification of the anodizing electrolyte which results in the codeposition of polyaniline during aluminum anodization. A second process, which incorporates electrochemical sealing of the anodic layer with polyaniline was also developed. The formation of these composite films is documented through experimental processing, and characterized by way of scientific analysis and engineering tests. Analysis results revealed the formation of unique dual phase anodic films with fine microstructures which exhibited full intrusion of the columnar aluminum oxide structure with polyaniline, indicating the polymer was deposited as the metal oxidation proceeded. An aromatic amine derivative of polyaniline with aluminum sulfate was determined to be the reaction product within the aluminum oxide phase of the codeposited films. Scientific characterization determined the codeposition process yields completely chemically and metallurgically bound composite films. Engineering studies determined the films, obtained through a single step, exhibited superior wear and corrosion resistance to conventionally anodized and sealed films processed through two steps, demonstrating the increased manufacturing process efficiency that can be realized with the modification of the

  9. Flexible composite film for printed circuit board

    Science.gov (United States)

    Yabe, K.; Asakura, M.; Tanaka, H.; Soda, A.

    1982-01-01

    A flexible printed circuit for a printed circuit board in which layers of reaction product composed of a combination of phenoxy resin - polyisocyanate - brominated epoxy resin, and in which the equivalent ratio of those functional groups is hydroxyl group: isocyanate group: epoxy group - 1 : 0.2 to 2 : 0.5 to 3 are laminated on at least one side of saturated polyester film is discussed.

  10. Changes in chemical composition and nanostructure of SiC thin films prepared by PECVD during thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Kuenle, Matthias; Janz, Stefan [Fraunhofer Institute of Solar Energy Systems ISE, Heidenhofstr. 2, 79110 Freiburg (Germany); Nickel, Klaus Georg [Applied Mineralogy, Institute for Geosciences, Eberhard-Karl-University Tuebingen, Wilhelmstr. 52, 72074 Tuebingen (Germany); Eibl, Oliver [Institute for Applied Physics, Eberhard-Karls-University Tuebingen, Auf der Morgenstelle 10, 72074 Tuebingen (Germany)

    2011-08-15

    Silicon carbide (SiC) thin films were deposited on silicon (Si) using plasma enhanced chemical vapor deposition (PECVD). Annealing was done in a rapid thermal annealing furnace at a temperature of 1300 C. As-deposited and annealed Si-rich and stoichiometric SiC thin films were investigated by analytical transmission electron microscopy (AEM). TEM-energy-dispersive X-ray spectroscopy was used to quantify the chemical composition of the SiC thin films with high accuracy. The chemical composition of the near stoichiometric SiC thin film changed during annealing from Si{sub 0.4}C{sub 0.6} to Si{sub 0.5}C{sub 0.5} due to diffusion of Si from the Si substrate into the film. The Si-rich Si{sub 1-x}C{sub x} film had the identical chemical composition of Si{sub 0.8}C{sub 0.2} before and after annealing. As-deposited films show nanoporosity within the bulk film. During annealing, v-shaped defect structures were formed at the interface of the stoichiometric SiC thin film to the Si substrate. Diffraction patterns revealed that as-deposited films were amorphous. During annealing the crystallization of 3C-SiC occurred in near-stoichiometric SiC thin films, whereas in Si-rich Si{sub 1-x}C{sub x} thin films two phases, namely Si and 3C-SiC, crystallized. Low-loss and core-loss electron energy loss spectroscopy (EELS) verified the diffraction results. In the low-loss spectra of the near stoichiometric SiC thin film, a plasmon peak located at 20.2 eV before and at 22.3 eV after annealing was detected. The low-loss spectra of the Si-rich Si{sub 1-x}C{sub x} thin film showed an asymmetric plasmon peak with two maxima located at 18.5 and 25.0 eV in the as-deposited film and 18.6 and 24.3 eV in the annealed Si-rich Si{sub 1-x}C{sub x} film. The 18.5 eV plasmon peaks is assigned to Si and the 25 eV plasmon peak is attributed to the SiC phase. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Solution Coating of Superior Large-Area Flexible Perovskite Thin Films with Controlled Crystal Packing

    KAUST Repository

    Li, Jianbo

    2017-05-08

    Solution coating of organohalide lead perovskites offers great potential for achieving low-cost manufacturing of large-area flexible optoelectronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of crystal packing. Herein, this study reports using solution shearing to confine crystal nucleation and growth in large-area printed MAPbI3 thin films. Near single-crystalline perovskite microarrays are demonstrated with a high degree of controlled macroscopic alignment and crystal orientation, which exhibit significant improvements in optical and optoelectronic properties comparing with their random counterparts, spherulitic, and nanograined films. In particular, photodetectors based on the confined films showing intense anisotropy in charge transport are fabricated, and the device exhibits significantly improved performance in all aspects by one more orders of magnitude relative to their random counterparts. It is anticipated that perovskite films with controlled crystal packing may find applications in high-performance, large-area printed optoelectronics, and solar cells.

  12. Physical and mechanical properties of modified bacterial cellulose composite films

    Science.gov (United States)

    Indrarti, Lucia; Indriyati, Syampurwadi, Anung; Pujiastuti, Sri

    2016-02-01

    To open wide range application opportunities of Bacterial Cellulose (BC) such as for agricultural purposes and edible film, BC slurries were blended with Glycerol (Gly), Sorbitol (Sor) and Carboxymethyl Cellulose (CMC). The physical and mechanical properties of BC composites were investigated to gain a better understanding of the relationship between BC and the additive types. Addition of glycerol, sorbitol and CMC influenced the water solubility of BC composite films. FTIR analysis showed the characteristic bands of cellulose. Addition of CMC, glycerol, and sorbitol slightly changed the FTIR spectrum of the composites. Tensile test showed that CMC not only acted as cross-linking agent where the tensile strength doubled up to 180 MPa, but also acted as plasticizer with the elongation at break increased more than 100% compared to that of BC film. On the other hand, glycerol and sorbitol acted as plasticizers that decreased the tensile strength and increased the elongation. Addition of CMC can improve film transparency, which is quite important in consumer acceptance of edible films in food industry.

  13. Nanocellulose-Zeolite Composite Films for Odor Elimination.

    Science.gov (United States)

    Keshavarzi, Neda; Mashayekhy Rad, Farshid; Mace, Amber; Ansari, Farhan; Akhtar, Farid; Nilsson, Ulrika; Berglund, Lars; Bergström, Lennart

    2015-07-08

    Free standing and strong odor-removing composite films of cellulose nanofibrils (CNF) with a high content of nanoporous zeolite adsorbents have been colloidally processed. Thermogravimetric desorption analysis (TGA) and infrared spectroscopy combined with computational simulations showed that commercially available silicalite-1 and ZSM-5 have a high affinity and uptake of volatile odors like ethanethiol and propanethiol, also in the presence of water. The simulations showed that propanethiol has a higher affinity, up to 16%, to the two zeolites compared with ethanethiol. Highly flexible and strong free-standing zeolite-CNF films with an adsorbent loading of 89 w/w% have been produced by Ca-induced gelation and vacuum filtration. The CNF-network controls the strength of the composite films and 100 μm thick zeolite-CNF films with a CNF content of less than 10 vol % displayed a tensile strength approaching 10 MPa. Headspace solid phase microextraction (SPME) coupled to gas chromatography-mass spectroscopy (GC/MS) analysis showed that the CNF-zeolite films can eliminate the volatile thiol-based odors to concentrations below the detection ability of the human olfactory system. Odor removing zeolite-cellulose nanofibril films could enable improved transport and storage of fruits and vegetables rich in odors, for example, onion and the tasty but foul-smelling South-East Asian Durian fruit.

  14. Bioinspired Transparent Laminated Composite Film for Flexible Green Optoelectronics.

    Science.gov (United States)

    Lee, Daewon; Lim, Young-Woo; Im, Hyeon-Gyun; Jeong, Seonju; Ji, Sangyoon; Kim, Yong Ho; Choi, Gwang-Mun; Park, Jang-Ung; Lee, Jung-Yong; Jin, Jungho; Bae, Byeong-Soo

    2017-07-19

    Herein, we report a new version of a bioinspired chitin nanofiber (ChNF) transparent laminated composite film (HCLaminate) made of siloxane hybrid materials (hybrimers) reinforced with ChNFs, which mimics the nanofiber-matrix structure of hierarchical biocomposites. Our HCLaminate is produced via vacuum bag compressing and subsequent UV-curing of the matrix resin-impregnated ChNF transparent paper (ChNF paper). It is worthwhile to note that this new type of ChNF-based transparent substrate film retains the strengths of the original ChNF paper and compensates for ChNF paper's drawbacks as a flexible transparent substrate. As a result, compared with high-performance synthetic plastic films, such as poly(ethylene terephthalate), poly(ether sulfone), poly(ethylene naphthalate), and polyimide, our HCLaminate is characterized to exhibit extremely smooth surface topography, outstanding optical clarity, high elastic modulus, high dimensional stability, etc. To prove our HCLaminate as a substrate film, we use it to fabricate flexible perovskite solar cells and a touch-screen panel. As far as we know, this work is the first to demonstrate flexible optoelectronics, such as flexible perovskite solar cells and a touch-screen panel, actually fabricated on a composite film made of ChNF. Given its desirable macroscopic properties, we envision our HCLaminate being utilized as a transparent substrate film for flexible green optoelectronics.

  15. Wettability of Nafion and Nafion/Vulcan carbon composite films.

    Science.gov (United States)

    Li, Xiaoan; Feng, Fangxia; Zhang, Ke; Ye, Siyu; Kwok, Daniel Y; Birss, Viola

    2012-04-24

    The wettability of the Pt/carbon/Nafion catalyst layer in proton exchange membrane fuel cells is critical to their performance and durability, especially the cathode, as water is needed for the transport of protons to the active sites and is also involved in deleterious Pt nanoparticle dissolution and carbon corrosion. Therefore, the focus of this work has been on the first-time use of the water droplet impacting method to determine the wettability of 100% Nafion films, as a benchmark, and then of Vulcan carbon (VC)/Nafion composite films, both deposited by spin-coating in the Pt-free state. Pure Nafion films, shown by SEM analysis to have a nanochanneled structure, are initially hydrophobic but become hydrophilic as the water droplet spreads, likely due to reorientation of the sulfonic acid groups toward water. The wettability of VC/Nafion composite films depends significantly on the VC/Nafion mass ratios, even though Nafion is believed to be preferentially oriented (sulfonate groups toward VC) in all cases. At low VC contents, a significant water droplet contact angle hysteresis is seen, similar to pure Nafion films, while at higher VC contents (>30%), the films become hydrophobic, also exhibiting superhydrophobicity, with surface roughness playing a significant role. At >80% VC, the surfaces become wettable again as there is insufficient Nafion loading present to fully cover the carbon surface, allowing the calculation of the Nafion:carbon ratio required for a full coverage of carbon by Nafion.

  16. Optical constants of yttrium-iron garnet single-crystal film structures

    Science.gov (United States)

    Sobol, V. R.; Volchik, T. V.; Arabei, S. M.; Korzun, B. V.; Kalanda, N. A.

    2009-03-01

    Light-attenuation spectra of yttrium-iron garnet single-crystal film structures grown on a gallium-gadolinium garnet substrate by liquid-phase epitaxy from the undercooled solution in the melt have been studied and compared with those of bulk yttrium-iron garnet samples. The calculated optical constants are discussed taking into account the influence of crystal field on the splitting of the energy states of iron ions in the film samples.

  17. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films.

    OpenAIRE

    Cho, N; Li, F; Turedi, B; Sinatra, L; Sarmah, SP; Parida,, B.; Saidaminov, MI; Murali, B; Burlakov, VM; Goriely, Alain; Mohammed, OF; Wu, T; Bakr, OM

    2016-01-01

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microa...

  18. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    OpenAIRE

    Cho, Namchul; LI Feng; Turedi, Bekir; Sinatra, Lutfan; Sarmah, Smritakshi P.; Parida, Manas R.; Saidaminov, Makhsud I.; Murali, Banavoth; Burlakov, Victor M.; Goriely, Alain; Mohammed, Omar F; Wu, Tom; Bakr, Osman M.

    2016-01-01

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microa...

  19. Composition and structure of CuInSe2 thin films prepared by vacuum evaporation of the constituent elements

    Science.gov (United States)

    Dhere, N. G.; Lourenco, M. C.; Dhere, R. G.; Kazmerski, L. L.

    1984-11-01

    The characteristics of CuInSe2 thin film solar cells produced by a three-source deposition method were investigated. The films were deposited at 350 C, followed by 30 min annealing at the same temperature. The compositions of the cells and intracell fractional variations were dependent on the proximity to the film source during formation. A chalcopyrite CuInSe2 structure was observed in X-ray diffraction patterns and high energy electron diffraction studies of the films on NaCl single crystal substrates. Grain sizes ranged from 0.2-0.6 micron, and the films had a band gap in the 1.02-1.04 eV interval.

  20. Preparation and characterisation of compositionally graded SmCo films

    Science.gov (United States)

    Dias, Andre; Gomez, Gabriel; Givord, Dominique; Bonfim, Marlio; Dempsey, Nora M.

    2017-05-01

    A compositionally graded SmCo film has been prepared by magnetron sputtering using a Co target partially covered by a Sm foil. The film was deposited onto a 100 mm thermally oxidised Si substrate and then annealed ex-situ. The SmCo film has been used as a test sample to validate an in-house developed scanning MOKE (Magneto-Optic Kerr effect) system incorporating a pulsed magnetic field source capable of producing fields as high as 10 T. A 2D array of hysteresis loops was measured across the entire wafer. The evolution in coercivity measured along a selected 1D strip of the sample is correlated with changes in composition and crystallographic structures measured using Energy Dispersive Spectroscopy and X-ray diffraction. The high field Scanning MOKE system holds much potential for optimizing the extrinsic properties of known hard magnetic phases as well as in the search for new hard magnetic phases.

  1. Preparation and characterization of CoFe2O4/TiO2 magnetic composite films

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    CoFe2O4/TiO2 magnetic composite films were prepared using the sol-gel method with tetrabutyltitanate and metallic chlorates as starting materials. The effects of heat treatment temperatures on micro- structures and on magnetic properties were studied. The microstructure and properties of the samples at different heat treatment temperatures were characterized by X-ray diffraction, Raman spectrum, scanning electron microscopy, polarized microscopy and vibrating sample magnetometry. The results show that crystals of different substances grow up independently. Cobalt ferrite is evenly embedded into the titanium dioxide matrix in the prepared composite films. The magnetism of the composite films is enhanced with an increase of the heat temperature.

  2. Thin film composite nanofiltration membranes for extreme conditions

    NARCIS (Netherlands)

    Dalwani, Mayur Ramesh

    2011-01-01

    The research presented in this thesis focuses on development and performance evaluation of thin film composite (TFC) nanofiltration (NF) membranes, with special attention to extreme pH applications. In Chapter 2 a new method that allows molecular weight cut off (MWCO) characterization of NF membran

  3. Gelatin-Pectin Composite Films from Polyion Complex Hydrogels

    Science.gov (United States)

    Composite films from gelatin and low-methoxyl pectin were prepared by either ionic complexation or covalent cross-linking. The ionic interactions between positively charged gelatin and negatively charged pectin produced physically reversible hydrogels. The resultant homogeneous gels had improved mec...

  4. Action of colloidal silica films on different nano-composites

    Science.gov (United States)

    Abdalla, S.; Al-Marzouki, F.; Obaid, A.; Gamal, S.

    Nano-composite films have been the subject of extensive work to develop the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nano-particles size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that form an insulating film between conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of 4 high pure amorphous polymer films: polymethylmethacrylate (PMMA), polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher break down performance is a character of polyimide PI and PMMA. Also, our experimental data shows that adding colloidal silica to PMMA and PI leads to a net decrease in the dielectric properties compared to the pure polymer.

  5. Dynamics of interstitial atoms and vacancies during the crystallization of amorphous Si and Ge films by flash lamp annealing

    Science.gov (United States)

    Matsuo, Naoto; Yoshioka, Naoki; Heya, Akira

    2017-08-01

    We examined the dynamics of interstitial atoms and vacancies in amorphous Si (a-Si) and a-Ge films crystallized by flash lamp annealing in consideration of the self-diffusion coefficients of Si and Ge. We found that the interstitial atoms play an important role in the liquid-phase crystallization (LPC) of a-Si films, whereas the vacancies are more important for the solid-phase crystallization (SPC) of a-Si films along with the LPC and SPC of a-Ge films. For Si, the crystal defect density of the film crystallized by LPC was higher than that of the film crystallized by SPC; the opposite result was achieved for Ge. This phenomenon is considered to be attributed to the existence of interstitial atoms introduced in Si. The thermodynamic calculated results related to the relationship between the point defect and SPC or LPC supported the crystallization mechanism.

  6. In situ Crystallization of RF sputtered ITO thin films: A comparison with annealed samples

    Energy Technology Data Exchange (ETDEWEB)

    John, K. Aijo [Junior research Fellow, Sree Sankara College, Kalady, Ernakulam - 683 574, Kerala (India); Manju, T. [Assistant Professor, Department of Physics, Sree Sankara College, Kalady, Ernakulam - 683 574, Kerala (India)

    2014-01-28

    Tin doped Indium Oxide (ITO) is a wide band gap semiconductor with high conductivity and transparency in the visible region of the solar spectrum. One of the most popular and exploited applications of ITO is the realization of the transparent conductive layers needed for the electrodes of light sensitive devices, such as photovoltaic cells. The thermal energy for the crystallization of ITO films is very low (150°C). The crystallization can be achieved by the continuous energetic bombardment of the ions in the sputtering chamber without annealing or substrate heating. The accumulated energy will ensure the thermal energy necessary for the crystallization. With the help of sufficiently high sputtering power and sufficient duration, crystallized ITO films can be produced without annealing. In this report, a comparison of the conductivity and transparency of ITO films under two crystallization conditions ((1) crystallization of the sputtered films by annealing; (2) in situ crystallization of the films by providing high sputtering power and long sputtering duration) will be presented.

  7. Enhanced crystallization of amorphous silicon thin films using embedded silicon nanocrystals

    Science.gov (United States)

    Anderson, Curtis Michael

    This thesis is concerned with the production of silicon thin films for photovoltaic applications. Much research has been carried out to find a stable, more efficient alternative to amorphous silicon, resulting in a number of various amorphous/crystalline mixed-phase film structures with properties superior to amorphous silicon. This thesis work details a completely new approach to mixed-phase film deposition, focusing on the fast crystallization of these films. The deposition of amorphous silicon films with embedded nanocrystals was carried out via a dual-plasma system. It is known that plasma conditions to produce high quality films are much different from those to produce particles. Hence the experimental system used here involved two separate plasmas to allow the optimum production of the crystalline nanoparticles and the amorphous film. Both plasmas use 13.56 MHz excitation voltage with diluted silane as the silicon precursor. The nanoparticle production reactor is a flow-through device that can be altered to control the size of the particles from around 5--30 nm average diameter. The film production reactor is a parallel-plate capacitively-coupled plasma system, into which the aerosol-suspended nanoparticles were injected. The nanocrystals could either be "co-deposited" simultaneously with the amorphous film, or be deposited separately in a layer-by-layer technique; both approaches are discussed in detail. Measurements of the film conductivity provide for the first time unambiguous evidence that the presence of nanocrystallites above 5 nm in the amorphous film have a direct impact on the electronic properties of co-deposited films. Further measurements of the film structure by transmission electron microscopy (TEM) and Raman spectroscopy demonstrate clearly the effect of embedded nanocrystals on the annealed crystallization process; the immediate growth of the crystal seeds has been observed. Additionally, a newly discovered mechanism of film crystallization

  8. Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

    KAUST Repository

    Abutaha, Anas I.

    2013-02-06

    We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature of the laser deposition process on LaAlO3 (100) substrates. The change in surface termination of the LaAlO3 substrate with temperature induces a change in AZO film orientation. The anisotropic nature of electrical conductivity and Seebeck coefficient of the AZO films showed a favored thermoelectric performance in c-axis oriented films. These films gave the highest power factor of 0.26 W m−1 K−1 at 740 K.

  9. Two hardening mechanisms in single crystal thin films studied by discrete dislocation plasticity

    NARCIS (Netherlands)

    Nicola, L; Van der Giessen, E; Needleman, A

    2005-01-01

    thermal stress in single crystal thin films on a rigid substrate are used to study size effects. The relation between the residual stress and the dislocation structure in the films after cooling is analyzed using dislocation dynamics. A boundary layer characterized by a high stress gradient and a hi

  10. Ternary carbon composite films for supercapacitor applications

    Science.gov (United States)

    Tran, Minh-Hai; Jeong, Hae Kyung

    2017-09-01

    A simple, binder-free, method of making supercapacitor electrodes is introduced, based on modification of activated carbon with graphite oxide and carbon nanotubes. The three carbon precursors of different morphologies support each other to provide outstanding electrochemical performance, such as high capacitance and high energy density. The ternary carbon composite shows six times higher specific capacitance compared to that of activated carbon itself with high retention. The excellent electrochemical properties of the ternary composite attribute to the high surface area of 1933 m2 g-1 and low equivalent series resistance of 2 Ω, demonstrating that it improve the electrochemical performance for supercapacitor applications.

  11. A comparison of grain nucleation and grain growth during crystallization of HWCVD and PECVD a-Si:H films

    NARCIS (Netherlands)

    Mahan, A.H.; Ahrenkiel, S.P.; Schropp, R.E.I.; Li, H. B. T.; Ginley, D.S.

    2008-01-01

    From TEM, XRD and Raman measurements, we compare the crystallization kinetics when HWCVD and PECVD a-Si:H films, containing different initial film hydrogen contents (CH), are crystallized by annealing at 600 °C. For the HWCVD films, the nucleation rate increases, and the incubation time and the full

  12. Enhancement effects of two kinds of carbon black on piezoelectricity of PVDF-HFP composite films

    Science.gov (United States)

    Hu, Bin; Hu, Ning; Wu, Liangke; Cui, Hao; Ying, Ji

    2015-12-01

    Two kinds of carbon black (CB) (i.e., CB#300 and CB#3350) were added into poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), respectively, to improve its piezoelectricity. The results revealed that when 0.5 wt.% CB was added, the best performance of the PVDF-HFP/CB composite films was obtained. The calibrated open circuit voltage and the density of harvested power of 0.5 wt.% CB#3350 contained composite films were 204%, and 464% (AC) and 561% (DC) of those of neat PVDF-HFP films. Similarly, for 0.5 wt.% CB#300 contained films, they were 211%, and 475% (AC) and 624% (DC), respectively. The enhancement mechanisms of piezoelectricity were clarified by the observation of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscope (SEM). We found that the added CBs act as nucleate agents to promote the formation of elongated, oriented and fibrillar β-phase crystals during the fabrication process, which increase the piezoelectricity. Overdosed CBs lead to a lower crystallinity degree, resulting in the lower piezoelectricity. Compared with CB#3350, CB#300 performs slightly better, which may be ascribed to its higher specific surface area.

  13. Preparation and photoelectrochemical performance of TiO2/Ag2Se interface composite film

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Coupling TiO2 with a narrow band gap semiconductor acting as the photosensitizer has attracted much attention in solar energy exploitation. In this work,the porous TiO2 film was first formed on the conducting glass plate (CGP) substrate by the decomposition of polyethylene glycol (PEG) mixing in titanium hydroxide sol at 450℃. Then,the TiO2/Ag2Se interface composite film was fabricated by interface reaction of AgNO3 with NaSeSO3 on the activated surface of porous TiO2 film. The results of SEM and XRD analyses indicated that the porous TiO2 layer was made up of the anatase crystal,and the Ag2Se layer was made up of congregative small particles that have low-temperature α-phase structure. Due to its efficient charge separation for the photo-induced electron-hole pairs,the TiO2/Ag2Se interface composite film as-prepared has good photovoltaic property and high photocurrent response for visible light,which have been confirmed by the photoelectrochemical measurements.

  14. Swift heavy ion irradiation induced phase transformation in undoped and niobium doped titanium dioxide composite thin films

    Science.gov (United States)

    Gautam, Subodh K.; Chettah, Abdelhak; Singh, R. G.; Ojha, Sunil; Singh, Fouran

    2016-07-01

    Study reports the effect of swift heavy ion (SHI) irradiation induced phase transformation in undoped and Niobium doped anatase TiO2 composite thin films. Investigations were carried out at different densities of electronic excitations (EEs) using 120 MeV Ag and 130 MeV Ni ions irradiations. Films were initially annealed at 900 °C and results revealed that undoped films were highly stable in anatase phase, while the Nb doped films showed the composite nature with the weak presence of Niobium penta-oxide (Nb2O5) phase. The effect at low density of EEs in undoped film show partial anatase to rutile phase transformation; however doped film shows only further growth of Nb2O5 phase beside the anatase to rutile phase transformation. At higher density of EEs induced by Ag ions, registered continuous ion track of ∼3 nm in lattice which leads to nano-crystallization followed by decomposition/amorphization of rutile TiO2 and Nb2O5 phases in undoped and doped films, respectively. However, Ni ions are only induced discontinuous sequence of ion tracks with creation of damage and disorder and do not show amorphization in the lattice. The in-elastic thermal spike calculations were carried out for anatase TiO2 phase to understand the effect of EEs on anatase to rutile phase transformation followed by amorphization in NTO films in terms of continuous and discontinuous track formation by SHI irradiation.

  15. PREPARATION AND PROPERTIES OF CHITOSAN/LIGNIN COMPOSITE FILMS

    Institute of Scientific and Technical Information of China (English)

    Long Chen; Chang-yu Tang; Nan-ying Ning; Chao-yu Wang; Qiang Fu; Qin Zhang

    2009-01-01

    Biodegradable composite films based on chitosan and lignin with various composition were prepared via the solution-casting technique.FT-IR results indicate the existence of hydrogen bonding between chitosan and lignin,and SEM images show that lignin could be well dispersed in chitosan when the content of lignin is below 20 wt% due to the strong interfacial interaction.As a result of strong interaction and good dispersion,the tensile strength,storage modulus,thermal degradation temperature and glass transition temperature of chitosan have been largely improved by adding lignin.Our work provides a simple and cheap way to prepare fully biodegradable chitosan/lignin composites,which could be used as packaging films or wound dressings.

  16. Annealing behaviour and crystal structure of RF-sputtered Bi-substituted dysprosium iron-garnet films having excess co-sputtered Bi-oxide content

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, M; Nur-E-Alam, M; Alameh, K [Electron Science Research Institute, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027 (Australia); Premchander, P; Lee, Y T [Department of Information and Communications, Gwangju Institute of Science and Technology (GIST), Gwangju, 500-712 (Korea, Republic of); Kotov, V A [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 11 Mohovaya St, Moscow, 125009 (Russian Federation); Lee, Y P, E-mail: m.vasiliev@ecu.edu.au [Quantum Photonic Science Research Center, Department of Physics, Hanyang University, 133-791 (Korea, Republic of)

    2011-02-23

    We investigate the magneto-optic properties, crystal structure and annealing behaviour of nano-composite media with record-high magneto-optic quality exceeding the levels reported so far in sputtered iron-garnet films. Bi-substituted dysprosium-gallium iron-garnet films having excess bismuth oxide content are deposited using RF co-sputtering, and a range of garnet materials are crystallized using conventional oven-annealing processes. We report, for the first time ever, the results of optimization of thermal processing regimes for various high-performance magneto-optic iron-garnet compositions synthesized and describe the evolution of the optical and magneto-optical properties of garnet-Bi-oxide composite-material films occurring during the annealing processes. The crystallization temperature boundaries of the system (BiDy){sub 3}(FeGa){sub 5}O{sub 12} : Bi{sub 2}O{sub 3} are presented. We also report the results of x-ray diffraction and energy-dispersive x-ray spectroscopy studies of this recently developed class of high-performance magneto-optic composites. Our hypothesis of iron oxides being the cause of excess optical absorption in sputtered Bi-iron-garnet films is confirmed experimentally.

  17. Investigation of tribological properties of composite C60-LB films

    Institute of Scientific and Technical Information of China (English)

    YANG Guanghong; ZHANG Xingtang; XUN Jun; JIANG Xiaohong; ZHANG Pingyu; DU Zuliang

    2006-01-01

    Composite C60-LB films were fabricated by the Langmuir-Blodgett (LB) technique, their micro- structures, micro- and macro-tribological properties were investigated using atomic force microscope/ friction force microscope (AFM/FFM). The results showed that in the confined C60-LB films there were two kinds of structures for the special C60 assembly: grain diameters of one kind were in the range of 150-230 nm; the other was smaller than 20 nm. Mi-cro-tribological studies showed that topographical images of tiny C60 aggregates (<20 nm) were con-sistent with their frictional ones very well, namely, low friction occurred on tiny C60 aggregates compared with fatty chains LB monolayer, and 'Micro-rolling effect' was apparent; but for big large ones frictional forces were relatively high and 'ratchet mechanism' was seen apparently. Macro-tribological data proved large C60 aggregates had wear resistance and load-carrying capacities and anti-wear lives for com- posite C60-LB films were prolonged greatly with dis-persibility of C60 improved and its grain diameter re-duced. Tiny C60 aggregates were mainly the lubricating agents. Friction coefficients of composite C60-LB films gradually reduced with loads increasing having the same friction coefficient-load relations with boundary lubrication films.

  18. REGULATED DEGRADABILITY OF COMPOSITE BIOBASED FILMS

    Directory of Open Access Journals (Sweden)

    Volodymyr M. Isaenko

    2008-02-01

    Full Text Available  Degradable biobased (derived from agriculture composites are emerging materials that offer benefits to the environment thus minimizing waste that would be otherwise deposited in landfills. Single-use primary packaging materials have been identified as suitable items to be replaced by biodegradable materials from renewable resources. Materials composed of starch, soy protein and polyvinylalcohol, modified by hydrophobic fatty acids, are evaluated in terms of water resistance as promising substitutes for packaging materials.

  19. Quantitative determination of hydrogen absorption by Pd cluster-assembled films using a quartz crystal microbalance

    Energy Technology Data Exchange (ETDEWEB)

    El Far, R.; Diaz-Droguett, D.E.; Rojas, S.; Avila, J.I. [Laboratorio de Ciencia de Materiales, Facultad de Fisica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Romero, C.P.; Lievens, P. [Laboratorium voor Vaste-Stoffysica en Magnetisme, KU Leuven, Celestijnenlaan 200D-bus 2414 B-3001 Leuven (Belgium); Cabrera, A.L., E-mail: acabrera@fis.puc.cl [Laboratorio de Ciencia de Materiales, Facultad de Fisica, Pontificia Universidad Catolica de Chile, Santiago (Chile)

    2012-11-01

    We have measured hydrogen absorption capacity for a series of Pd films grown by two deposition techniques: a) flat films made with e-beam evaporation of Pd and b) films made of assembled Pd clusters. The films range in thickness from 9.5 to 45 nm. The technique implemented for measuring the amount of hydrogen absorbed by the films was a quartz crystal microbalance. The Pd films were grown on the quartz crystals and the change of mass due to the hydrogen absorption was determined from the shifting of the resonance frequency. Minute amounts of hydrogen absorbed of the order of nanograms per square centimeter can be detected by this technique. Plots of H/Pd atom ratio for each Pd film as a function of hydrogen pressure were obtained. The Pd e-beam grown films displayed a saturation H/Pd atomic ratio around 0.6 which is similar to bulk Pd. The Pd cluster film with a thickness of 14 nm displayed a remarkable absorption capacity with a ratio H/(Pd) Almost-Equal-To 0.84. - Highlights: Black-Right-Pointing-Pointer Pd cluster assembled films with different thicknesses are made and characterized. Black-Right-Pointing-Pointer Quartz crystal microbalance is used to quantification the hydrogen amount absorbed. Black-Right-Pointing-Pointer Hydrogen absorption/adsorption by Pd film is explained. Black-Right-Pointing-Pointer Absorption expressed in H/Pd mass ratio is given for all Pd films. Black-Right-Pointing-Pointer This complements H{sub 2} absorption on metal cluster films using optical techniques.

  20. Structural, compositional and morphological studies of thermally evaporated MoO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Senthilkumar, R., E-mail: raviganesa@rediffmail.com, E-mail: gravicrc@gmail.com; Ravi, G., E-mail: raviganesa@rediffmail.com, E-mail: gravicrc@gmail.com [Department of Physics, Alagappa University, Karaikudi - 630003 (India)

    2014-04-24

    Molybdenum oxide (MoO{sub 3}) nanostructures were grown on different substrates such as glass, indium tin oxide coated glass and fluorine doped glass by thermal evaporation of MoO{sub 3} powder at elevated temperature (750°C) using tube furnace without any catalyst and then by subsequent O{sub 2}/Ar flow rate. The morphology, composition and crystal structure were examined by using SEM, EDAX, Laser Raman and XRD. The films are polycrystalline with well-defined diffraction peaks and it consist of MoO{sub 3} with α-orthorhombic structure. The synthesized MoO{sub 3} belongs to different morphologies, generally nanobelt and nanohunk structures. The EDAX spectra confirm the films are composed only of Mo and O atoms. The O/Mo ratio is nearly equal to 3 that shows the stoichiometry of MoO{sub 3}.

  1. The ion capturing effect of 5° SiOx alignment films in liquid crystal devices

    Science.gov (United States)

    Huang, Yi; Bos, Philip J.; Bhowmik, Achintya

    2010-09-01

    We show that SiOx, deposited at 5° to the interior surface of a liquid crystal cell allows for a surprisingly substantial reduction in the ion concentration of liquid crystal devices. We have investigated this effect and found that this type of film, due to its surface morphology, captures ions from the liquid crystal material. Ion adsorption on 5° SiOx film obeys the Langmuir isotherm. Experimental results shown allow estimation of the ion capturing capacity of these films to be more than an order of 10 000/μm2. These types of materials are useful for new types of very low power liquid crystal devices such as e-books.

  2. Determination of the Origin of Crystal Orientation for Nanocrystalline Bismuth Telluride-Based Thin Films Prepared by Use of the Flash Evaporation Method

    Science.gov (United States)

    Takashiri, M.; Tanaka, S.; Miyazaki, K.

    2014-06-01

    We have investigated the origin of crystal orientation for nanocrystalline bismuth telluride-based thin films. Thin films of p-type bismuth telluride antimony (Bi-Te-Sb) and n-type bismuth telluride selenide (Bi-Te-Se) were fabricated by a flash evaporation method, with exactly the same deposition conditions except for the elemental composition of the starting powders. For p-type Bi-Te-Sb thin films the main x-ray diffraction (XRD) peaks were from the c-axis (Σ{00l}/Σ{ hkl} = 0.88) whereas n-type Bi-Te-Se thin films were randomly oriented (Σ{00l}/Σ{ hkl} = 0.40). Crystal orientation, crystallinity, and crystallite size were improved for both types of thin film by sintering. For p-type Bi-Te-Sb thin films, especially, high-quality structures were obtained compared with those of n-type Bi-Te-Se thin films. We also estimated the thermoelectric properties of the as-grown and sintered thin films. The power factor was enhanced by sintering; maximum values were 34.9 μW/cm K2 for p-type Bi-Te-Sb thin films at a sintering temperature of 300°C and 23.9 μW/cm K2 for n-type Bi-Te-Se thin films at a sintering temperature of 350°C. The exact mechanisms of film growth are not yet clear but we deduce the crystal orientation originates from the size of nano-clusters generated on the tungsten boat during flash evaporation.

  3. Composite Fermion Theory for the High Field Wigner Crystal State

    Science.gov (United States)

    Narevich, Romanas; Murthy, Ganpathy; Fertig, Herbert

    2001-03-01

    The low filling fraction Quantum Hall Effect is reexamined using the hamiltonian composite fermion theory developed by Shankar and Murthy(R. Shankar and G. Murthy, Phys. Rev. Lett. 79), 4437 (1997). We address the experiment by Jiang et. al.(H. W. Jiang et. al., Phys. Rev. B 44), 8107 (1991) where the insulating phase surrounding the ν=1/5 quantum liquid was observed and its activation energies (gaps) measured. Previous studies either found gaps that were off by few orders of magnitude (Hartree-Fock calculations of the electronic Wigner crystal(D. Yoshioka and H. Fukuyama, J. Phys. Soc. Japan 47), 394 (1979)) or were unable to calculate them because of the computational complexity (Monte-Carlo studies of the correlated crystal(H. Yi and H. A. Fertig, Phys. Rev. B 58), 4019 (1998)). We use the Hartree-Fock approximation for the periodic density state of composite fermions and find gaps that have a correct order of magnitude and reproduce the experimental dependence on the filling factor. We also report the results of the shear modulus calculation relevant for the collective pinning of the crystal.

  4. Novel Transrotational Solid State Order Discovered by TEM in Crystallizing Amorphous Films

    Science.gov (United States)

    Kolosov, Vladimir

    Exotic thin crystals with unexpected transrotational microstructures have been discovered by transmission electron microscopy (TEM) for crystal growth in thin (10-100 nm) amorphous films of different chemical nature (oxides, chalcogenides, metals and alloys) prepared by various methods. Primarily we use our TEM bend contour technique. The unusual phenomenon can be traced in situ in TEM column: dislocation independent regular internal bending of crystal lattice planes in a growing crystal. Such transrotation (unit cell trans lation is complicated by small rotationrealized round an axis lying in the film plane) can result in strong regular lattice orientation gradients (up to 300 degrees per micrometer) of different geometries: cylindrical, ellipsoidal, toroidal, saddle, etc. Transrotation is increasing as the film gets thinner. Transrotational crystal resembles ideal single crystal enclosed in a curved space. Transrotational micro crystals have been eventually recognized by other authors in some vital thin film materials, i.e. PCMs for memory, silicides, SrTiO3. Atomic model and possible mechanisms of the phenomenon are discussed. New transrotational nanocrystalline model of amorphous state is also proposed Support of RF Ministry of Education and Science is acknowledged.

  5. High Performance Thin-Film Composite Forward Osmosis Membrane

    KAUST Repository

    Yip, Ngai Yin

    2010-05-15

    Recent studies show that osmotically driven membrane processes may be a viable technology for desalination, water and wastewater treatment, and power generation. However, the absence of a membrane designed for such processes is a significant obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation onto a thin (40 μm) polyester nonwoven fabric. By careful selection of the polysulfone casting solution (i.e., polymer concentration and solvent composition) and tailoring the casting process, we produced a support layer with a mix of finger-like and sponge-like morphologies that give significantly enhanced membrane performance. The structure and performance of the new thin-film composite forward osmosis membrane are compared with those of commercial membranes. Using a 1.5 M NaCl draw solution and a pure water feed, the fabricated membranes produced water fluxes exceeding 18 L m2-h-1, while consistently maintaining observed salt rejection greater than 97%. The high water flux of the fabricated thin-film composite forward osmosis membranes was directly related to the thickness, porosity, tortuosity, and pore structure of the polysulfone support layer. Furthermore, membrane performance did not degrade after prolonged exposure to an ammonium bicarbonate draw solution. © 2010 American Chemical Society.

  6. Structural and biological properties of carbon nanotube composite films

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Roger J. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)]. E-mail: roger.narayan@mse.gatech.edu; Berry, C.J. [Environmental Biotechnology Section, Savannah River National Laboratory, Aiken, SC 29808 (United States); Brigmon, R.L. [Environmental Biotechnology Section, Savannah River National Laboratory, Aiken, SC 29808 (United States)

    2005-11-20

    Carbon nanotube composite films have been developed that exhibit unusual structural and biological properties. These novel materials have been created by pulsed laser ablation of graphite and bombardment of nitrogen ions at temperatures between 600 and 700 deg. C. High-resolution transmission electron microscopy and radial distribution function analysis demonstrate that this material consists of sp{sup 2}-bonded concentric ribbons that are wrapped approximately 15 deg. normal to the silicon substrate. The interlayer order in this material extends to approximately 15-30 A. X-ray photoelectron spectroscopy and Raman spectroscopy data suggest that this material is predominantly trigonally coordinated. The carbon nanotube composite structure results from the use of energetic ions, which allow for non-equilibrium growth of graphitic planes. In vitro testing has revealed significant antimicrobial activity of carbon nanotube composite films against Staphylococcus aureus and Staphylococcus warneri colonization. Carbon nanotube composite films may be useful for inhibiting microorganism attachment and biofilm formation in hemodialysis catheters and other medical devices.

  7. EFFECT OF MOLECULAR WEIGHT AND FILM THICKNESS ON THE CRYSTALLIZATION AND MICROPHASE SEPARATION IN POLYSTYRENE BLOCK-POLY(L-LACTIC ACID) THIN FILMS AT THE EARLY STAGE

    Institute of Scientific and Technical Information of China (English)

    Yu-han Wei; Cai-yuan Pan; Bin-yao Li; Xin-hong Yu; Yan-chun Han

    2011-01-01

    We investigated the effects of molecular weight and film thickness on the crystallization and microphase separation in semicrystalline block copolymer polystyrene-block-poly(L-lactic acid) (PS-b-PLLA) thin films, at the early stage of film evolution (when Ts < T < TODT) by in situ hot stage atomic force microscopy. For PS-b-PLLA 1 copolymer which had lower molecular weight and higher PLLA fraction, diffusion-controlled break-out crystallization started easily.For PS-b-PLLA 2 with higher molecular weight, crystallization in nanometer scales occurs in local area. After melting of the two copolymer films, islands were observed at the film surface: PS-b-PLLA 1 film was in a disordered phase mixed state while PS-b-PLLA 2 film formed phase-separated lamellar structure paralleling to the substratc. Crystallization-melting and van der Waals forces drove the island formation in PS-b-PLLA 1 film. Film thickness affected the crystallization rate. Crystals grew very slowly in much thinner film ofPS-b-PLLA 1 and remained almost unchanged at long time annealing. The incompatibility between PS and PLLA blocks drove the film fluctuation which subsequently evolved into spinodal-like morphology.

  8. Investigating the crystal growth behavior of biodegradable polymer blend thin films using in situ atomic force microscopy

    CSIR Research Space (South Africa)

    Malwela, T

    2014-01-01

    Full Text Available This article reports the crystal growth behavior of biodegradable polylactide (PLA)/poly[(butylene succinate)-co-adipate] (PBSA) blend thin films using atomic force microscopy (AFM). Currently, polymer thin films have received increased research...

  9. Induced growth of high quality ZnO thin films by crystallized amorphous ZnO

    Institute of Scientific and Technical Information of China (English)

    Wang Zhi-Jun; Song Li-Jun; Li Shou-Chun; Lu You-Ming; Tian Yun-Xia; Liu Jia-Yi; Wang Lian-Yuan

    2006-01-01

    This paper reports the induced growth of high quality ZnO thin film by crystallized amorphous ZnO. Firstly amorphous ZnO was prepared by solid-state pyrolytic reaction, then by taking crystallized amorphous ZnO as seeds (buffer layer), ZnO thin films have been grown in diethyene glycol solution of zinc acetate at 80℃. X-ray Diffraction curve indicates that the films were preferentially oriented [001] out-of-plane direction of the ZnO. Atomic force microscopy and scanning electron microscopy were used to evaluate the surface morphology of the ZnO thin film. Photoluminescence spectrum exhibits a strong ultraviolet emission while the visible emission is very weak. The results indicate that high quality ZnO thin film was obtained.

  10. Composition change and capacitance properties of ruthenium oxide thin film

    Institute of Scientific and Technical Information of China (English)

    刘泓; 甘卫平; 刘仲武; 郑峰

    2015-01-01

    RuO2·nH2O film was deposited on tantalum foils by electrodeposition and heat treatment using RuCl3·3H2O as precursor. Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·nH2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2 h, RuO2·nH2O electrode surface gains mass of 2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly 20%with voltage scan rate increasing from 5 to 250 mV/s.

  11. CW laser induced crystallization of thin amorphous silicon films deposited by EBE and PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Said-Bacar, Z., E-mail: zabardjade@yahoo.fr [InESS (UMR 7163 CNRS-UDS), 23 rue de Loess, 67037 Strasbourg Cedex 2 (France); Prathap, P. [InESS (UMR 7163 CNRS-UDS), 23 rue de Loess, 67037 Strasbourg Cedex 2 (France); Cayron, C. [CEA, LITEN, DEHT, Minatec, 17 rue des Martyrs, 38054 Cedex 9 (France); Mermet, F. [IREPA LASER, Pole API - Parc d' Innovation, 67400 Illkirch (France); Leroy, Y.; Antoni, F.; Slaoui, A.; Fogarassy, E. [InESS (UMR 7163 CNRS-UDS), 23 rue de Loess, 67037 Strasbourg Cedex 2 (France)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer The effect of hydrogen in CW laser crystallization of hydrogenated amorphous silicon thin films has been investigated. Black-Right-Pointing-Pointer Large hydrogen content results in decohesion of the films due to hydrogen effusion. Black-Right-Pointing-Pointer Very low hydrogen content or hydrogen free amorphous silicon film are suitable for crystallization induced by CW laser. Black-Right-Pointing-Pointer Grains of size between 20 and 100 {mu}m in width and about 200 {mu}m in long in scanning direction are obtained with these latter films. - Abstract: This work presents the Continuous Wave (CW) laser crystallization of thin amorphous silicon (a-Si) films deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and by Electron Beam Evaporation (EBE) on low cost glass substrate. The films are characterized by Elastic Recoil Detection Analysis (ERDA) and by Fourier-Transform Infrared (FTIR) spectroscopy to evaluate the hydrogen content. Analysis shows that the PECVD films contain a high hydrogen concentration ({approx}10 at.%) while the EBE films are almost hydrogen-free. It is found that the hydrogen is in a bonding configuration with the a-Si network and in a free form, requiring a long thermal annealing for exodiffusion before the laser treatment to avoid explosive effusion. The CW laser crystallization process of the amorphous silicon films was operated in liquid phase regime. We show by Electron Backscatter Diffraction (EBSD) that polysilicon films with large grains can be obtained with EBE as well as for the PECVD amorphous silicon provided that for the latest the hydrogen content is lower than 2 at.%.

  12. Self-assembled ordered structures in thin films of HAT5 discotic liquid crystal

    Directory of Open Access Journals (Sweden)

    Piero Morales

    2010-05-01

    Full Text Available Thin films of the discotic liquid crystal hexapentyloxytriphenylene (HAT5, prepared from solution via casting or spin-coating, were investigated by atomic force microscopy and polarizing optical microscopy, revealing large-scale ordered structures substantially different from those typically observed in standard samples of the same material. Thin and very long fibrils of planar-aligned liquid crystal were found, possibly formed as a result of an intermediate lyotropic nematic state arising during the solvent evaporation process. Moreover, in sufficiently thin films the crystallization seems to be suppressed, extending the uniform order of the liquid crystal phase down to room temperature. This should be compared to the bulk situation, where the same material crystallizes into a polymorphic structure at 68 °C.

  13. Single-Crystal Mesoporous ZnO Thin Films Composed of Nanowalls

    KAUST Repository

    Wang, Xudong

    2009-02-05

    This paper presents a controlled, large scale fabrication of mesoporous ZnO thin films. The entire ZnO mesoporous film is one piece of a single crystal, while high porosity made of nanowalls is present. The growth mechanism was proposed in comparison with the growth of ZnO nanowires. The ZnO mesoporous film was successfully applied as a gas sensor. The fabrication and growth analysis of the mesoporous ZnO thin film gi ve general guidance for the controlled growth of nanostructures. It also pro vides a unique structure with a superhigh surface-to-volume ratio for surface-related applications. © 2009 American Chemical Society.

  14. Imitation of variable structural color in Paracheirodon innesi using colloidal crystal films.

    Science.gov (United States)

    Cong, Hailin; Yu, Bing; Zhao, Xiu Song

    2011-06-20

    Spacing variation of adjoining reflecting thin films in iridophore is responsible for the variable interference color in the paracheirodon innesi. On the basis of this phenomenon, colloidal crystal thin films with different structures are fabricated from monodisperse poly(styrene-methyl methacrylate-acrylic acid) (PSMA) colloids. The relationship between the colors and structures of the films is investigated and discussed according to the principle of light interference. A two-layer colloidal film having uniform color is researched and it displays diverse colors before and after swelling by styrene (St), which can be used to mimic the variable structural color of the paracheirodon innesi.

  15. THE PREPARATION AND STUDY ON THE NANO-TiO2/SILK FIBROIN COMPOSITE FILMS BY THE SOL-GEL METHOD

    Institute of Scientific and Technical Information of China (English)

    FENG Xinxing; CHEN Jianyong; YU Chunhua

    2006-01-01

    Based on the sol-gel technique using butyl titanate as oxide precursor, the regenerated SF (silk fibroin)/nano-TiO2 composite films were synthesized. Different amounts of butyl titanate to SF were used to verify this effect on the characteristics of the formed materials. Samples were characterized by thermogravimetric analysis, X-ray diffractometry, UV, AFM and FT-IR spectroscopy.The experimental results reveal that, compared to the pure silk fibroin films, the mechanical strength of these regenerated SF/nano-TiO2 composite films were increased and the dissolubility in water of SF/nano-TiO2 composite films in aqueous solution were decreased. The diameter of nano-TiO2 particle films was about 80nm through UV and AFM. The nano-TiO2 particles were well dispersed in the regenerated silk fibroin. It was found that the crystal structures of the composite films were transited from typical Silk Ⅰ to typical Silk Ⅱ by the XRD and FTIR. Furthermore, the crystallinity of the composite films was obviously improved. Through the TGA, it was demonstrated that the heat transition temperature of composite films was also enhanced.

  16. Influence of secondary phases during annealing on re-crystallization of CuInSe{sub 2} electrodeposited films

    Energy Technology Data Exchange (ETDEWEB)

    Gobeaut, A. [Laboratoire de Reactivite et Chimie des Solides, 33 rue St Leu, 80039 Amiens (France); Laffont, L., E-mail: lydia.laffont@u-picardie.f [Laboratoire de Reactivite et Chimie des Solides, 33 rue St Leu, 80039 Amiens (France); Tarascon, J.-M. [Laboratoire de Reactivite et Chimie des Solides, 33 rue St Leu, 80039 Amiens (France); Parissi, L.; Kerrec, O. [Institut de Recherche et de Developpement de l' Energie Photovoltaique, 6 quai Watier, 78401 Chatou cedex (France)

    2009-06-01

    Electrodeposited CuInSe{sub 2} thin films are of potential importance, as light absorber material, in the next generation of photovoltaic cells as long as we can optimize their annealing process to obtain dense and highly crystalline films. The intent of this study was to gain a basic understanding of the key experimental parameters governing the structural-textural-composition evolution of thin films as function of the annealing temperature via X-ray diffraction, scanning/transmission electron microscopy and thermal analysis measurements. The crystallization of the electrodeposited CuInSe{sub 2} films, with the presence of Se and orthorhombic Cu{sub 2} {sub -} {sub x}Se (o-Cu{sub 2} {sub -} {sub x}Se) phases, occurs over two distinct temperature ranges, between 220 {sup o}C and 250 {sup o}C and beyond 520 {sup o}C. Such domains of temperature are consistent with the melting of elemental Se and the binary CuSe phase, respectively. The CuSe phase forming during annealing results from the reaction between the two secondary species o-Cu{sub 2} {sub -} {sub x}Se and Se (o-Cu{sub 2} {sub -} {sub x}Se + Se {yields} 2 CuSe) but can be decomposed into the cubic {beta}-Cu{sub 2} {sub -} {sub x}Se phase by slowing down the heating rate. Formation of liquid CuSe beyond 520{sup o}C seems to govern both the grain size of the films and the porosity of the substrate-CuInSe{sub 2} film interface. A simple model explaining the competitive interplay between the film crystallinity and the interface porosity is proposed, aiming at an improved protocol based on temperature range, which will enable to enhance the film crystalline nature while limiting the interface porosity.

  17. Densification and crystallization of SnO{sub 2}:Sb sol-gel films using excimer laser annealing

    Energy Technology Data Exchange (ETDEWEB)

    Sandu, C.S.; Teodorescu, V.S.; Ghica, C.; Canut, B.; Blanchin, M.G.; Roger, J.A.; Brioude, A.; Bret, T.; Hoffmann, P.; Garapon, C

    2003-03-15

    We have successfully applied laser annealing to sol-gel deposited SnO{sub 2}:Sb thin films in order to achieve their crystallization. The as-deposited films are quasi-amorphous and electrically non-conductive. After laser annealing they crystallize and become conductive. This paper presents a comparative study of the laser annealed films and shows the influence of the irradiation parameters on the crystallization process and the electrical behavior of the films. Our results are quite promising in view of applying this kind of treatment to films deposited on thermally sensitive substrates (e.g. polymers)

  18. Thin film composition with biological substance and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Allison A. (Kennewick, WA); Song, Lin (Richland, WA)

    1999-01-01

    The invention provides a thin-film composition comprising an underlying substrate of a first material including a plurality of attachment sites; a plurality of functional groups chemically attached to the attachment sites of the underlying substrate; and a thin film of a second material deposited onto the attachment sites of the underlying substrate, and a biologically active substance deposited with the thin-film. Preferably the functional groups are attached to a self assembling monolayer attached to the underlying substrate. Preferred functional groups attached to the underlying substrate are chosen from the group consisting of carboxylates, sulfonates, phosphates, optionally substituted, linear or cyclo, alkyl, alkene, alkyne, aryl, alkylaryl, amine, hydroxyl, thiol, silyl, phosphoryl, cyano, metallocenyl, carbonyl, and polyphosphate. Preferred materials for the underlying substrate are selected from the group consisting of a metal, a metal alloy, a plastic, a polymer, a proteic film, a membrane, a glass or a ceramic. The second material is selected from the group consisting of inorganic crystalline structures, inorganic amorphus structures, organic crystalline structures, and organic amorphus structures. Preferred second materials are phosphates, especially calcium phosphates and most particularly calcium apatite. The biologically active molecule is a protein, peptide, DNA segment, RNA segment, nucleotide, polynucleotide, nucleoside, antibiotic, antimicrobal, radioisotope, chelated radioisotope, chelated metal, metal salt, anti-inflamatory, steriod, nonsteriod anti-inflammatory, analgesic, antihistamine, receptor binding agent, or chemotherapeutic agent, or other biologically active material. Preferably the biologically active molecule is an osteogenic factor the compositions listed above.

  19. Thin film composition with biological substance and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, A.A.; Song, L.

    1999-09-28

    The invention provides a thin-film composition comprising an underlying substrate of a first material including a plurality of attachment sites; a plurality of functional groups chemically attached to the attachment sites of the underlying substrate; and a thin film of a second material deposited onto the attachment sites of the underlying substrate, and a biologically active substance deposited with the thin-film. Preferably the functional groups are attached to a self assembling monolayer attached to the underlying substrate. Preferred functional groups attached to the underlying substrate are chosen from the group consisting of carboxylates, sulfonates, phosphates, optionally substituted, linear or cyclo, alkyl, alkene, alkyne, aryl, alkylaryl, amine, hydroxyl, thiol, silyl, phosphoryl, cyano, metallocenyl, carbonyl, and polyphosphate. Preferred materials for the underlying substrate are selected from the group consisting of a metal, a metal alloy, a plastic, a polymer, a proteic film, a membrane, a glass or a ceramic. The second material is selected from the group consisting of inorganic crystalline structures, inorganic amorphous structures, organic crystalline structures, and organic amorphous structures. Preferred second materials are phosphates, especially calcium phosphates and most particularly calcium apatite. The biologically active molecule is a protein, peptide, DNA segment, RNA segment, nucleotide, polynucleotide, nucleoside, antibiotic, antimicrobial, radioisotope, chelated radioisotope, chelated metal, metal salt, anti-inflammatory, steroid, nonsteroid anti-inflammatory, analgesic, antihistamine, receptor binding agent, or chemotherapeutic agent, or other biologically active material. Preferably the biologically active molecule is an osteogenic factor consisting of the compositions listed above.

  20. Heat flow description during crystallization process of cast dispersive composites

    Directory of Open Access Journals (Sweden)

    Cholewa M.

    2007-01-01

    Full Text Available The aim of this work was to show possibilities of numerical simulation software, based on heat transfer model, commonly used in foundry industry in cast composite properties engineering. The main restriction in most of used software systems is lack of heat transfer, which may occur at composite creation. In this work the reinforcing particle morphology an size were expressed by one quantity – morphological modulus Mm and were examined for influence on heat transfer and conductivity up to the Newton’s and Fourier’s laws. The main restrictions for using Fourier’s model based software for composite engineering are shown. The way for crystallization control was presented including influence of morphology, transition zone and thermo-physical properties of components. Proposed methodology can be used for cast composite properties engineering in cases, where relative motion of components is negligible. In other cases heat transfer coefficient is justified only if the software used is based on Fourier’s model and the source code is accessible. Proposed assumptions create possibility for components selection verification in terms of technological and operating properties of cast composite. An example of such approach was shown in work [1, 23].

  1. Effect of preheating on the film thickness of contemporary composite restorative materials

    Directory of Open Access Journals (Sweden)

    Dimitrios Dionysopoulos

    2014-12-01

    Conclusion: The film thickness of the composites tested is material dependent. The thickness of the preheated conventional composites is significantly lower than those at room temperature. The conventional composites provide film thickness values greater than those of the flowable composites regardless of preheating temperature.

  2. The Preparation of Cellulose/Collagen Composite Films using 1-Ethyl-3-Methylimidazolium Acetate as a Solvent

    Directory of Open Access Journals (Sweden)

    Min Zhang

    2013-12-01

    Full Text Available Cellulose/collagen composite films with weight ratios of 30/1 (Blend-1 and 10/1 (Blend-2 were prepared using 1-ethyl-3-methylimidazolium acetate as a common solvent. The morphology of the films observed with a field-emission scanning electron microscope displayed a dependence on the ratio of cellulose/collagen. Collagen was successfully composited with cellulose without degradation and showed a denaturation temperature (Td higher than that of native collagen. Fourier transform infrared spectroscopy suggested that there were hydrogen-bond interactions between collagen and cellulose in the regenerated composite films. Thermogravimetric analysis revealed that the maximum decomposition temperature (Tmax of cellulose decreased after regeneration, while the Tmax of Blend-1 increased; however, it was reduced again for Blend-2. Elastic moduli from dynamic mechanical analysis exhibited a trend similar to that of Tmax. As indicated by X-ray diffraction, the distance between cellulose molecular chains was shortened for Blend-1 and elongated for Blend-2. Furthermore, the crystallization indices were calculated to be 75.3%, 68.3%, 66.2%, and 55.4% for native cellulose, regenerated films of cellulose, Blend-1, and Blend-2, respectively. These results confirm the dependence of the structural properties of composite films on cellulose/collagen ratios through the interactions between cellulose and collagen.

  3. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    KAUST Repository

    Cho, Nam Chul

    2016-11-10

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microarrays that are distinguishable from general polycrystalline perovskite materials in terms of their crystal orientation, film morphology and electronic properties. X-ray diffraction patterns reveal that the film is strongly oriented in the (112) and (200) planes parallel to the substrate. This film is structurally confined by directional crystal growth, inducing intense anisotropy in charge transport. In addition, the low trap-state density (7.9 × 1013 cm−3) leads to strong amplified stimulated emission. This ability to control crystal orientation and morphology could be widely adopted in optoelectronic devices.

  4. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    Science.gov (United States)

    Cho, Namchul; Li, Feng; Turedi, Bekir; Sinatra, Lutfan; Sarmah, Smritakshi P.; Parida, Manas R.; Saidaminov, Makhsud I.; Murali, Banavoth; Burlakov, Victor M.; Goriely, Alain; Mohammed, Omar F.; Wu, Tom; Bakr, Osman M.

    2016-11-01

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microarrays that are distinguishable from general polycrystalline perovskite materials in terms of their crystal orientation, film morphology and electronic properties. X-ray diffraction patterns reveal that the film is strongly oriented in the (112) and (200) planes parallel to the substrate. This film is structurally confined by directional crystal growth, inducing intense anisotropy in charge transport. In addition, the low trap-state density (7.9 × 1013 cm-3) leads to strong amplified stimulated emission. This ability to control crystal orientation and morphology could be widely adopted in optoelectronic devices.

  5. Molecular interactions in gelatin/chitosan composite films.

    Science.gov (United States)

    Qiao, Congde; Ma, Xianguang; Zhang, Jianlong; Yao, Jinshui

    2017-11-15

    Gelatin and chitosan were mixed at different mass ratios in solution forms, and the rheological properties of these film-forming solutions, upon cooling, were studied. The results indicate that the significant interactions between gelatin and chitosan promote the formation of multiple complexes, reflected by an increase in the storage modulus of gelatin solution. Furthermore, these molecular interactions hinder the formation of gelatin networks, consequently decreasing the storage modulus of polymer gels. Both hydrogen bonds and electrostatic interactions are formed between gelatin and chitosan, as evidenced by the shift of the amide-II bands of polymers. X-ray patterns of composite films indicate that the contents of triple helices decrease with increasing chitosan content. Only one glass transition temperature (Tg) was observed in composite films with different composition ratios, and it decreases gradually with an increase in chitosan proportion, indicating that gelatin and chitosan have good miscibility and form a wide range of blends. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Zeta-potential of fouled thin film composite membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, K.; Hachisuka, H.; Nakamura, T. [Nitto denko Corp., Ibaraki, (Japan); Kimura, S. [Kogakuin University, Tokyo (Japan). Dept. of Environ. Chemical Engineering; Ueyama, K. [Osaka University, Osaka (Japan). Dept. of Chemical Engineering

    1999-10-01

    The surface zeta-potential of a cross-linked polyamide thin film composite reverse osmosis membrane was measured using an electrophoresis method. It was confirmed that this method could be effectively applied to analyze the fouling of such membranes. It is known that the water flux of membranes drastically decreases as a result of fouling by surfactants. Although the surfactants adsorbed on reverse osmosis membranes could not be detected by conventional methods such as SEM, EDX and FT-IR, their presence could be clarified by the profile measurements of the surface zeta-potential. The profiles of the membrane surface zeta-potentials changed to more positive values in the measured pH range as a result of fouling by cationic or amphoteric surfactants. This measuring method of surface zeta-potentials allowed us to analyze a very small amount of fouling of a thin film composite reverse osmosis membrane. This method could be used to analyze the fouled surface of the thin film composite reverse osmosis membrane which is used for production of ultrapure water and shows a remarkable decrease in flux. It also became clear that this method is easy and effective for the reverse osmosis membrane surface analysis of adsorbed materials such as surfactants. (author)

  7. Luminescence study of ZnSe/PVA (polyvinyl alcohol) composite film

    Energy Technology Data Exchange (ETDEWEB)

    Lahariya, Vikas [Amity School of Applied Science, Amity University Haryana Panchgaon, Manesar, Haryana 122413 (India)

    2016-05-06

    The ZnSe nanocrystals have been prepared into poly vinyl alcohol(PVA) polymer matrix on glass using ZnCl2 and Na2SeSO3 as zinc and selenium source respectively. Poly vinyl Alcohol (PVA) used as polymer matrix cum capping agent due to their high viscosity and water solubility. It is transparent for visible region and prevents Se- ions to photo oxidation. The ZnSe/PVA composite film was deposited on glass substrate. The film was characterized by X Ray Diffraction (XRD) and UV-Visible absorption Spectroscopy and Photoluminescence. The X Ray Diffraction (XRD) study confirms the nanometer size (10 nm) particle formation within PVA matrix with cubic zinc blend crystal structure. The UV-Visible Absorption spectrum of ZnSe/PVA composite film shown blue shift in absorption edge indicating increased band gap due to quantum confinement. The calculated energy band gap from the absorption edge using Tauc relation is 3.4 eV. From the Photoluminescence study a broad peak at 435 nm has been observed in violet blue region due to recombination of surface states.

  8. Silica-Copper Oxide Composite Thin Films as Solar Selective Coatings Prepared by Dipping Sol Gel

    Directory of Open Access Journals (Sweden)

    E. Barrera-Calva

    2008-01-01

    Full Text Available Silica-copper oxide (silica-CuO composite thin films were prepared by a dipping sol-gel route using ethanolic solutions comprised TEOS and a copper-propionate complex. Sols with different TEOS/Cu-propionate (Si/Cu molar ratios were prepared and applied on stainless steel substrates using dipping process. During the annealing process, copper-propionate complexes developed into particulate polycrystalline CuO dispersed in a partially crystallized silica matrix, as indicated by the X-ray diffraction (XRD and X-ray photoelectron spectroscopy (XPS analyses. The gel thermal analysis revealed that the prepared material might be stable up to 400°C. The silica-CuO/stainless steel system was characterized as a selective absorber surface and its solar selectivity parameters, absorptance (α, and emittance (ε were evaluated from UV-NIR reflectance data. The solar parameters of such a system were mostly affected by the thickness and phase composition of the SiO2-CuO film. Interestingly, the best solar parameters (α = 0.92 and ε = 0.2 were associated to the thinnest films, which comprised a CuO-Cu2O mixture immersed in the silica matrix, as indicated by XPS.

  9. Preparation and Properties of Silver Nanowire-Based Transparent Conductive Composite Films

    Science.gov (United States)

    Tian, Ji-Li; Zhang, Hua-Yu; Wang, Hai-Jun

    2016-06-01

    Silver nanowire-based transparent conductive composite films with different structures were successfully prepared using various methods, including liquid polyol, magnetron sputtering and spin coating. The experimental results revealed that the optical transmittance of all different structural composite films decreased slightly (1-3%) compared to pure films. However, the electrical conductivity of all composite films had a great improvement. Under the condition that the optical transmittance was greater than 78% over the wavelength range of 400-800 nm, the AgNW/PVA/AgNW film became a conductor, while the AZO/AgNW/AZO film and the ITO/AgNW/ITO film showed 88.9% and 94% reductions, respectively, for the sheet resistance compared with pure films. In addition, applying a suitable mechanical pressure can improve the conductivity of AgNW-based composite films.

  10. Polymer Wall Formation Using Liquid-Crystal/Polymer Phase Separation Induced on Patterned Polyimide Films

    Science.gov (United States)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2004-12-01

    We could form lattice-shaped polymer walls in a liquid crystal (LC) layer through the thermal phase separation of an LC/polystyrene solution between substrates with polyimide films etched by short-wavelength ultraviolet irradiation using a photomask. The LC wetting difference between the polyimide and substrate surfaces caused the coalescence of growing LC droplets on patterned polyimide films with the progress of phase separation. Consequently, polymer walls were formed on substrate surface areas without polyimide films. The shape of the polymer wall formed became sharp with the use of rubbed polyimide films because the nucleation of growing LC droplets concentrated on the patterned polyimide films. It is thought that the increase in the alignment order of LC molecules in the solution near the rubbed polyimide films promotes the formation of LC molecular aggregation, which becomes the growth nuclei of LC droplets.

  11. Experimental studies of crystal-melt differentiation in planetary basalt compositions

    Science.gov (United States)

    Grove, T. L.

    1987-01-01

    An important process that controls the evolution of magmas on and within planetary bodies is crystal-melt differentiation. Experimental studies of silicate melt solidification were performed on several planetary and terrestrial melt compositions, and experiments on one of these compositions in the microgravity environment of the space station would provide an opportunity to understand the factors that control crystal growth and crystal-melt exchange processes at crystal-melt interfaces during solidification. Experimental requirements are presented.

  12. Composition and structure of Ti-C/DLC graded composite films

    Institute of Scientific and Technical Information of China (English)

    孙明仁; 夏立芳

    2002-01-01

    The Ti-C→DLC gradient composite films were characterized systematically.The elemental depth profile and elemental chemical state evolution were determined by X-ray photoelectron spectroscopy (XPS).The transmission electron microscope (TEM) and high-resolution transmission electron microscopy (HRTEM) were used to study the structure of interfacial zone between DLC film and Ti-C layers.Results show that there are composition transition zone between DLC film and either Ti-C layer or steel substrate on condition that pre-deposited Ti layers on the steel substrate then plasma based bias deposited DLC films.In Ti-C graded layer,the chemical state of titanium and carbon are changed gradually.The structures of zone in Ti-C layer near the DLC film is consisted of random oriented nanocrystallines TiC dispersed in amorphous DLC matrix.The structure of the zone between DLC film and Ti-C graded layer is gradually changed too.

  13. Formation of Al-Si Composite Oxide Film by Hydrolysis Precipitation and Anodizing

    Institute of Scientific and Technical Information of China (English)

    Zhe-Sheng Feng; Ying-Jie Xia; Jia Ding; Jin-Ju Chen

    2007-01-01

    This paper presents a new technique in the high dielectric constant composite oxide film preparation.On the basis of nanocompsite high dielectric constant aluminum oxide film growth technology, a new idea of adulterating Si oxide species into the aluminum composite film was proposed. As a result, the specific capacitance and withstanding voltage of the composite oxide film formed at the anodizing voltage of 20V are enhanced, and the leakage current of the aluminum composite oxide film is reduced through incorporation of Si oxide species.

  14. Near infrared to ultraviolet optical properties of bulk single crystal and nanocrystal thin film iron pyrite

    Science.gov (United States)

    Subedi, Indra; Bhandari, Khagendra P.; Ellingson, Randall J.; Podraza, Nikolas J.

    2016-07-01

    We report optical properties of iron pyrite (FeS2) determined from ex situ spectroscopic ellipsometry measurements made on both a commercially available bulk single crystal and nanocrystalline thin film over a spectral range of 0.735-5.887 eV. The complex dielectric function, ɛ (E) = ɛ 1 (E) + iɛ 2 (E), spectra have been determined by fitting a layered parametric model to the ellipsometric measurements. Spectra in ɛ are modeled using a Kramers-Kronig consistent critical point parabolic band model involving seven critical points for the bulk single crystal and four critical points for the nanocrystalline film. Absorption coefficient spectra for both types of samples are also determined from ɛ. Critical point features in the nanocrystalline films are broader, have lower amplitude and lower energy critical points detected having a small blue shift when compared to the single crystal sample.

  15. Magnetic coupling mechanisms in particle/thin film composite systems

    Directory of Open Access Journals (Sweden)

    Giovanni A. Badini Confalonieri

    2010-12-01

    Full Text Available Magnetic γ-Fe2O3 nanoparticles with a mean diameter of 20 nm and size distribution of 7% were chemically synthesized and spin-coated on top of a Si-substrate. As a result, the particles self-assembled into a monolayer with hexagonal close-packed order. Subsequently, the nanoparticle array was coated with a Co layer of 20 nm thickness. The magnetic properties of this composite nanoparticle/thin film system were investigated by magnetometry and related to high-resolution transmission electron microscopy studies. Herein three systems were compared: i.e. a reference sample with only the particle monolayer, a composite system where the particle array was ion-milled prior to the deposition of a thin Co film on top, and a similar composite system but without ion-milling. The nanoparticle array showed a collective super-spin behavior due to dipolar interparticle coupling. In the composite system, we observed a decoupling into two nanoparticle subsystems. In the ion-milled system, the nanoparticle layer served as a magnetic flux guide as observed by magnetic force microscopy. Moreover, an exchange bias effect was found, which is likely to be due to oxygen exchange between the iron oxide and the Co layer, and thus forming of an antiferromagnetic CoO layer at the γ-Fe2O3/Co interface.

  16. Influence of the crystal orientation on the electrical properties of AlN thin films on LTCC substrates

    Energy Technology Data Exchange (ETDEWEB)

    Bittner, A., E-mail: achim.bittner@tuwien.ac.at [Micromechanics, Microfluidics/Microactuators, Faculty of Natural Sciences and Technology II, Saarland University, D-66123 Saarbruecken (Germany); Ababneh, A.; Seidel, H. [Micromechanics, Microfluidics/Microactuators, Faculty of Natural Sciences and Technology II, Saarland University, D-66123 Saarbruecken (Germany); Schmid, U. [Department for Microsystems Technology, Institute of Sensor and Actuator Systems, Vienna University of Technology, Floragasse 7, A-1040 Vienna (Austria)

    2010-11-15

    In this study, the influence of the crystal orientation on the electrical properties of sputter deposited aluminium nitride (AlN) thin films on low temperature co-fired ceramics (LTCC) substrates is investigated. The degree of c-axis orientation can be tailored by the deposition conditions such as plasma power, gas pressure and gas composition in the deposition chamber. Due to the large surface roughness of LTCC substrates (R{sub a} = {approx}0.4 {mu}m) the quality of thin films is lower compared to silicon. Between areas of columnar grains arranged perpendicular to the LTCC surface, defects like voids are generated due to the wavy surface characteristics. The impact of crystal orientation and temperature up to 400 deg. C on the electrical performance is evaluated, as these layers are targeted as potential candidates for dielectric heat spreaders on multilayered ceramic substrates for high frequency applications. These AlN thin films having a good c-axis orientation exhibit lower leakage current levels over the complete temperature range compared to those with a poor alignment with respect to this crystallographic plane. The leakage current behaviour, however, is dominated according to the Pool-Frenkel electron emission independent of the degree of c-axis orientation.

  17. Fabrication of ZnO Nanoneedle/nanocolumn Composite Films and Annealing Induced Improvement in Their Microstructural and Photoluminescence Characteristics

    Institute of Scientific and Technical Information of China (English)

    Dongjiang QIU; Ping YU; Yintu JIANG; Huizhen WU

    2006-01-01

    ZnO nanoneedle/nanocolumn (NN/NC) composite films were grown via reactive electron beam evaporation(REBE) in the NH3/H2 gaseous mixture by using polycrystalline ZnO ceramic targets as source materials. The growth was performed at low substrate temperatures (450~500℃) without employing any metallic catalysts.As-prepared samples were then rapidly annealed in O2 ambient at a higher temperature (600℃). Electron microscopic observations revealed the typical composite-structured morphologies of NN/NC/substrate of ZnO nanomaterials grown at 500℃. Such unique morphologies should render potential applications, for instance,as an efficient microwave absorption material utilized in the fabrication of concealed aerostat. In addition,X-ray diffraction and photoluminescence measurements showed remarkable improvement in crystal and optical qualities of ZnO NN/NC composite films after annealing.

  18. Crystallization and oxygen loading in pulsed laser deposited YSZ-films

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, Benedikt; Liese, Tobias; Hoffmann, Sarah; Krebs, Hans-Ulrich [Institut fuer Materialphysik, University of Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)

    2011-07-01

    Yttria-stabilized zirconium dioxide (YSZ) as an oxygen ion conductor is widely used in technical applications, for example as solid oxide fuel cells. Thus, it is important studying the film stability at higher temperatures. In this contribution, amorphous YSZ films prepared by Pulsed Laser Deposition (PLD) at room temperature and annealed in argon/vacuum or oxygen atmosphere are presented. In a first thermal treatment in high vacuum up to temperatures of 800 C a loss of oxygen and crystallization of the film is achieved. Further heating in oxygen atmosphere leads to a reversible reloading of oxygen in the film. At this, changing the heating time and temperature enables to obtain different levels of oxygen in the samples. The weight change during outgasing and reloading was measured by thermal gravimetric analysis (TGA). The structure of different oxygen states and dynamics of crystallization was characterized by in-situ X-ray diffraction (XRD) and ellipsometry.

  19. Realization of hydrodynamic experiments on quasi-2D liquid crystal films in microgravity

    Science.gov (United States)

    Clark, Noel A.; Eremin, Alexey; Glaser, Matthew A.; Hall, Nancy; Harth, Kirsten; Klopp, Christoph; Maclennan, Joseph E.; Park, Cheol S.; Stannarius, Ralf; Tin, Padetha; Thurmes, William N.; Trittel, Torsten

    2017-08-01

    Freely suspended films of smectic liquid crystals are unique examples of quasi two-dimensional fluids. Mechanically stable and with quantized thickness of the order of only a few molecular layers, smectic films are ideal systems for studying fundamental fluid physics, such as collective molecular ordering, defect and fluctuation phenomena, hydrodynamics, and nonequilibrium behavior in two dimensions (2D), including serving as models of complex biological membranes. Smectic films can be drawn across openings in planar supports resulting in thin, meniscus-bounded membranes, and can also be prepared as bubbles, either supported on an inflation tube or floating freely. The quantized layering renders smectic films uniquely useful in 2D fluid physics. The OASIS team has pursued a variety of ground-based and microgravity applications of thin liquid crystal films to fluid structure and hydrodynamic problems in 2D and quasi-2D systems. Parabolic flights and sounding rocket experiments were carried out in order to explore the shape evolution of free floating smectic bubbles, and to probe Marangoni effects in flat films. The dynamics of emulsions of smectic islands (thicker regions on thin background films) and of microdroplet inclusions in spherical films, as well as thermocapillary effects, were studied over extended periods within the OASIS (Observation and Analysis of Smectic Islands in Space) project on the International Space Station. We summarize the technical details of the OASIS hardware and give preliminary examples of key observations.

  20. Magnetostrictive behaviors of Fe-Al(001 single-crystal films under rotating magnetic fields

    Directory of Open Access Journals (Sweden)

    Tetsuroh Kawai

    2016-05-01

    Full Text Available Magnetostrictive behaviors of Fe100−x − Alx(x = 0 − 30 at.%(001 single-crystal films under rotating magnetic fields are investigated along the two different crystallographic orientations, [100] and [110]. The behaviors of Fe and Fe90Al10 films show bath-tub like waveform along [100], easy magnetization axis, and triangular waveform along [110], hard magnetization axis, with respect to their four-fold magnetic anisotropy. On the other hand, the behaviors of Fe80Al20 film are different from those of Fe or Fe90Al10 film. The output of the film along [100] shows a strong magnetic field dependence. The Fe70Al30 film shows similar magnetostrictive behaviors along both [100] and [110] reflecting its magnetic properties, which are almost same for the both directions. The growth of ordered phase (B2 in Fe80Al20 and Fe70Al30 films is considered to have affected their magnetostrictive behaviors. The Al content dependence on λ100 and λ111 values shows similar tendency to that reported for the bulk samples but the values are slightly different. The Fe90Al10(001 single-crystal film shows a large magnetostriction along [100] under a very small magnetic field of 0.02 kOe, which is comparable to the saturated one, and changes the value abruptly in relation to the angle of applied magnetic field.

  1. Oxide films: low-temperature deposition and crystallization

    Science.gov (United States)

    Park, Sangmoon; Herman, Gregory S.; Keszler, Douglas A.

    2003-10-01

    Thin films of CeO 2 and (Ce,Sm)O 2 have been prepared by using the SILAR method of deposition in conjunction with hydrothermal and high-temperature annealing. Low-temperature, low-pressure hydrothermal annealing of amorphous Mn:Zn 2GeO 4 films has lead to the growth of grains having edge lengths near 1 μm. Thick films of crystalline Zn 2SiO 4 exhibiting limited cracking have been prepared by a doctor-blade method also in conjunction with hydrothermal dehydration and annealing.

  2. Controllable crystallization and enhanced amorphous stability of Sb-Te films modified by Ag-doping

    Science.gov (United States)

    Zhong, Juechen; Luo, Yang; Gu, Ting; Wang, Zhenglai; Jiang, Kefeng; Wang, Guoxiang; Lu, Yegang

    2016-10-01

    Ag-doped Sb-Te films were deposited by magnetron co-sputtering and the structure, electrical, optical and thermal properties were analyzed. The results show that Ag-doping restrains crystal grain size, and changes a preferred orientation of the crystalline phase. The crystallization temperature is increased due to the Ag addition. Both amorphous resistance and crystalline resistance are enhanced and the resistance ratio reaches ˜104. Compared with Ge2Sb2Te5, Ag26.82(Sb3Te)73.18 film exhibits a better amorphous thermal stability, a higher crystallization temperature (˜166 °C), a wider optical band gap (0.515 eV), a larger crystallization activation energy (3.17 eV) as well as a better 10 years data retention at 92 °C.

  3. COMPENSATION EFFECT OF POLYIMIDE THIN FILMS ON NORMALLY WHITE TWISTED NEMATIC LIQUID CRYSTAL DISPLAYS

    Institute of Scientific and Technical Information of China (English)

    LI Baozhong; HE Tianbai; DING Mengxian

    1997-01-01

    The disadvantages of Normally White Twisted Nematic Liquid Crystal Display (NW-TN-LCD) were discussed. The reason that the negative birefringent polyimide thin films were used to compensate NW-TN-LCD to decrease off-axis leakage, improve contrast ratios and enlarge viewing angles' was explained in this paper. A certain polyimide thin film was taken as an example to show compensation effect on NW-TN-LCD.

  4. Enhanced transduction of photonic crystal dye lasers for gas sensing via swelling polymer film

    DEFF Research Database (Denmark)

    Smith, Cameron; Lind, Johan Ulrik; Christiansen, Mads Brøkner;

    2011-01-01

    We present the enhanced transduction of a photonic crystal dye laser for gas sensing via deposition of an additional swelling polymer film. Device operation involves swelling of the polymer film during exposure to specific gases, leading to a change in total effective refractive index. Experimental...... in its application to other intracavity-based detection schemes to enable gas sensing. © 2011 Optical Society of America....

  5. Aluminium-induced crystallization of amorphous silicon films deposited by DC magnetron sputtering on glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kezzoula, F., E-mail: kezzoula@usa.com [UDTS 2Bd Frantz Fanon 7 merveilles Algiers (Algeria); Laboratory of Materials, Mineral and Composite (LMMC), Boumerdes University (Algeria); Hammouda, A. [UPR CNRS 3079 CEMHTI - 1D Avenue de la Recherche Scientifique, 45071 Orleans Cedex 2 (France); Equipe Couches Minces, Laboratoire de Physique des Materiaux, Faculte de Physique, USTHB, Algiers (Algeria); Universite d' Orleans, 45067 Orleans Cedex 2 (France); Kechouane, M. [Equipe Couches Minces, Laboratoire de Physique des Materiaux, Faculte de Physique, USTHB, Algiers (Algeria); Simon, P. [UPR CNRS 3079 CEMHTI - 1D Avenue de la Recherche Scientifique, 45071 Orleans Cedex 2 (France); Universite d' Orleans, 45067 Orleans Cedex 2 (France); Abaidia, S.E.H. [Laboratory of Materials, Mineral and Composite (LMMC), Boumerdes University (Algeria); Keffous, A. [UDTS 2Bd Frantz Fanon 7 merveilles Algiers (Algeria); Cherfi, R. [Equipe Couches Minces, Laboratoire de Physique des Materiaux, Faculte de Physique, USTHB, Algiers (Algeria); Menari, H.; Manseri, A. [UDTS 2Bd Frantz Fanon 7 merveilles Algiers (Algeria)

    2011-09-15

    Amorphous silicon (a-Si) and hydrogenated amorphous silicon (a-Si:H) films were deposited by DC magnetron sputtering technique with argon and hydrogen plasma mixture on Al deposited by thermal evaporation on glass substrates. The a-Si/Al and a-Si:H/Al thin films were annealed at different temperatures ranging from 250 to 550 deg. C during 4 h in vacuum-sealed bulb. The effects of annealing temperature on optical, structural and morphological properties of as-grown as well as the vacuum-annealed a-Si/Al and a-Si:H/Al thin films are presented in this contribution. The averaged transmittance of a-Si:H/Al film increases upon increasing the annealing temperature. XRD measurements clearly evidence that crystallization is initiated at 450 deg. C. The number and intensity of diffraction peaks appearing in the diffraction patterns are more important in a-Si:H/Al than that in a-Si/Al layers. Results show that a-Si:H films deposited on Al/glass crystallize above 450 deg. C and present better crystallization than the a-Si layers. The presence of hydrogen induces an improvement of structural properties of poly-Si prepared by aluminium-induced crystallization (AIC).

  6. Effect of electrical field on crystallization and ferroelectric properties of Ge:Sb:Te films

    Energy Technology Data Exchange (ETDEWEB)

    Gervacio Arciniega, J.J.; Prokhorov, E.; Espinoza Beltran, F.J.; Trapaga Martinez, L.G. [CINVESTAV, Unidad Queretaro (Mexico); Gonzalez-Hernandez, J. [Centro de Investigacion en Materiales Avanzados, S.C. and Laboratorio Nacional de Nanotecnologia, Chihuahua (Mexico)

    2011-11-15

    In this work impedance spectroscopy has been used to investigate of the NaCl type-hexagonal transition in stoichiometric Ge{sub 2}Sb{sub 2}Te{sub 5} and in non-stoichiometric (Ge{sub 24}Sb{sub 15}Te{sub 61}) films. The temperature dependence of capacitance in all films shows an abrupt change (about 4-6 times) at the temperature corresponding to the end of the NaCl type-hexagonal transition. Additional, impedance measurements were carried out in films which have been crystallized with an external DC electric field. Comparing the results in the films crystallized with and without the external electric field, it is observed that in films crystallized with an external electric field, the capacitance increases during the NaCl type-hexagonal transition for about 9-15 times and that the piezoresponse force microscopy measurements have shown ferroelectric domains in the NaCl type phase. External electrical field changes significantly the onset of amorphous-NaCl type crystallization temperature which could be related with an increase in atomic diffusion, promoting the growth of the crystalline phase. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. KTN thin films prepared by pulsed laser deposition on transparent single crystal quartz (100)

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiaodong; PENG; Xiaofeng; ZHANG; Duanming

    2005-01-01

    Using the Sol-Gel method to produce the KTN ultrafine powder and the sintering technique with K2O atmosphere to prepare KTN ceramics as the targets instead of the KTN single crystal, highly oriented KTN thin films were produced on the transparent single crystal quartz (100) by the pulsed laser deposition (PLD). Since the thermal stress sustained by the quartz is relatively small, the limit temperature of the quartz substrates(300℃) is much lower than that of the P-Si substrates (560℃); the prepared thin film is at amorphous state. Increasing the pulsed laser energy density in the process incorporated with annealing the film after deposition at different temperatures converts the amorphous films into crystal. The optimal pulsed laser energy density and annealing temperature were 2.0 J/cm2 and 600℃, respectively. A discussion was made to understand the mechanism of film production at relatively low substrate temperature by PLD and effects of the annealing temperatures on the forming of the perovskite phase, and optimal conditions for the orientation of the crystal grain.

  8. Rupture mechanism of liquid crystal thin films realized by large-scale molecular simulations

    Science.gov (United States)

    Nguyen, Trung Dac; Carrillo, Jan-Michael Y.; Matheson, Michael A.; Brown, W. Michael

    2014-02-01

    The ability of liquid crystal (LC) molecules to respond to changes in their environment makes them an interesting candidate for thin film applications, particularly in bio-sensing, bio-mimicking devices, and optics. Yet the understanding of the (in)stability of this family of thin films has been limited by the inherent challenges encountered by experiment and continuum models. Using unprecedented large-scale molecular dynamics (MD) simulations, we address the rupture origin of LC thin films wetting a solid substrate at length scales similar to those in experiment. Our simulations show the key signatures of spinodal instability in isotropic and nematic films on top of thermal nucleation, and importantly, for the first time, evidence of a common rupture mechanism independent of initial thickness and LC orientational ordering. We further demonstrate that the primary driving force for rupture is closely related to the tendency of the LC mesogens to recover their local environment in the bulk state. Our study not only provides new insights into the rupture mechanism of liquid crystal films, but also sets the stage for future investigations of thin film systems using peta-scale molecular dynamics simulations.The ability of liquid crystal (LC) molecules to respond to changes in their environment makes them an interesting candidate for thin film applications, particularly in bio-sensing, bio-mimicking devices, and optics. Yet the understanding of the (in)stability of this family of thin films has been limited by the inherent challenges encountered by experiment and continuum models. Using unprecedented large-scale molecular dynamics (MD) simulations, we address the rupture origin of LC thin films wetting a solid substrate at length scales similar to those in experiment. Our simulations show the key signatures of spinodal instability in isotropic and nematic films on top of thermal nucleation, and importantly, for the first time, evidence of a common rupture mechanism

  9. Some Lower Valence Vanadium Fluorides: Their Crystal Distortions, Domain Structures, Modulated Structures, Ferrimagnetism, and Composition Dependence.

    Science.gov (United States)

    Hong, Y. S.; And Others

    1980-01-01

    Describes some contemporary concepts unique to the structure of advanced solids, i.e., their crystal distortions, domain structures, modulated structures, ferrimagnetism, and composition dependence. (Author/CS)

  10. Preparation of high-quality poly-Si films by a solid phase crystallizing method

    CERN Document Server

    Yao Ruo He

    2002-01-01

    A solid phase crystallizing method has been developed to grow a Si crystal at temperatures as low as 550 degree C. Using this method, a high-quality thin-film polycrystalline silicon (Poly-Si) was obtained. The largest grain size, examined with X-ray diffraction spectroscopy and scanning electron microscopy images of recrystallized samples, is approximately 1 mu m for substrate temperature at 300 degree C and annealed at 550 degree C for 3 hours

  11. Strongly Dichroic Organic Films via Controlled Assembly of Modular Aromatic Charge-Transfer Liquid Crystals.

    Science.gov (United States)

    Bé, Ariana Gray; Tran, Cheryl; Sechrist, Riley; Reczek, Joseph J

    2015-10-02

    The formation of highly anisotropic organic thin films based on the designed self-assembly of mixed-stack liquid crystals is reported. A series of alkoxyanthracene donors is combined in a modular fashion with a naphthalenediimide acceptor to generate new charge-transfer columnar liquid crystals. Materials characterization and molecular modeling provides insight into structure-function relationships in these organic materials that lead to the striking bulk dichroic properties of certain molecular assemblies.

  12. Influence of Substrate on Crystal Orientation of Large-Grained Si Thin Films Formed by Metal-Induced Crystallization

    Directory of Open Access Journals (Sweden)

    Kaoru Toko

    2015-01-01

    Full Text Available Producing large-grained polycrystalline Si (poly-Si film on glass substrates coated with conducting layers is essential for fabricating Si thin-film solar cells with high efficiency and low cost. We investigated how the choice of conducting underlayer affected the poly-Si layer formed on it by low-temperature (500°C Al-induced crystallization (AIC. The crystal orientation of the resulting poly-Si layer strongly depended on the underlayer material: (100 was preferred for Al-doped-ZnO (AZO and indium-tin-oxide (ITO; (111 was preferred for TiN. This result suggests Si heterogeneously nucleated on the underlayer. The average grain size of the poly-Si layer reached nearly 20 µm for the AZO and ITO samples and no less than 60 µm for the TiN sample. Thus, properly electing the underlayer material is essential in AIC and allows large-grained Si films to be formed at low temperatures with a set crystal orientation. These highly oriented Si layers with large grains appear promising for use as seed layers for Si light-absorption layers as well as for advanced functional materials.

  13. Photoactive composite films prepared from mixtures of polystyrene microgel dispersions and poly(3-hexylthiophene) solutions.

    Science.gov (United States)

    Chen, Mu; Cui, Zhengxing; Edmondson, Steve; Hodson, Nigel; Zhou, Mi; Yan, Junfeng; O'Brien, Paul; Saunders, Brian R

    2015-11-14

    Whilst polystyrene microgels belong to the oldest family of microgel particles, their behaviours when deposited onto substrates or prepared as composites have received little attention. Because polystyrene microgels are solvent-swellable, and inherently colloidally stable, they are well suited to form composites with conjugated polymers. Here, we investigate the morphology and light absorption properties of spin coated composite films prepared from mixed dispersions of polystyrene microgels and poly(3-hexylthiophene) (P3HT) for the first time. We compare the morphologies of the composite films to spin coated microgel films. The films were studied using optical microscopy, SEM, AFM, wide-angle X-ray diffraction and UV-visible spectroscopy. The films contained flattened microgel particles with an aspect ratio of ∼10. Microgel islands containing hexagonally close packed particles were evident for both the pure microgel and microgel/P3HT composite films. The latter were electrically conducting. The composite film morphology was dependent on the microgel and P3HT concentration used for film preparation and a morphology phase diagram was constructed. The P3HT phase acted as an electrically conducting cement and increased the robustness of the films to solvent washing. The composite films were photoactive due to the P3HT component. The absorbance for the films was tuneable and increased linearly with both microgel and P3HT concentration. The results of the study should apply to other organic swellable microgel/conjugated polymer combinations and may lead to new colloidal composites for future optoelectronic applications.

  14. Development and physicochemical characterization of alginate composite film loaded with simvastatin as a potential wound dressing.

    Science.gov (United States)

    Rezvanian, Masoud; Amin, Mohd Cairul Iqbal Mohd; Ng, Shiow-Fern

    2016-02-10

    Previously, studies have demonstrated that topical application of simvastatin can promote wound healing in diabetic mice via augmentation of angiogenesis and lymphangiogenesis. This study aimed to formulate and characterize simvastatin in alginate-based composite film wound dressings. Biopolymers used for composite films were sodium alginate blended with pectin or gelatin. The films were prepared and characterized based on their physical properties, surface morphology, mechanical strength and rheology. Then, in vitro drug releases from the films were investigated and, finally, the cell viability assay was performed to assess the cytotoxicity profile. From the pre-formulation studies, alginate/pectin composite film showed to possess desirable wound dressing properties and superior mechanical properties. The in vitro drug release profile revealed that alginate/pectin film produced a controlled release drug profile, and cell viability assay showed that the film was non-toxic. In summary, alginate/pectin composite film is suitable to be formulated with simvastatin as a potential wound dressing.

  15. Compositional Effects on Nickel-Base Superalloy Single Crystal Microstructures

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Garg,Anita; Rogers, Richard B.; Nathal, Michael V.

    2012-01-01

    Fourteen nickel-base superalloy single crystals containing 0 to 5 wt% chromium (Cr), 0 to 11 wt% cobalt (Co), 6 to 12 wt% molybdenum (Mo), 0 to 4 wt% rhenium (Re), and fixed amounts of aluminum (Al) and tantalum (Ta) were examined to determine the effect of bulk composition on basic microstructural parameters, including gamma' solvus, gamma' volume fraction, volume fraction of topologically close-packed (TCP) phases, phase chemistries, and gamma - gamma'. lattice mismatch. Regression models were developed to describe the influence of bulk alloy composition on the microstructural parameters and were compared to predictions by a commercially available software tool that used computational thermodynamics. Co produced the largest change in gamma' solvus over the wide compositional range used in this study, and Mo produced the largest effect on the gamma lattice parameter and the gamma - gamma' lattice mismatch over its compositional range, although Re had a very potent influence on all microstructural parameters investigated. Changing the Cr, Co, Mo, and Re contents in the bulk alloy had a significant impact on their concentrations in the gamma matrix and, to a smaller extent, in the gamma' phase. The gamma phase chemistries exhibited strong temperature dependencies that were influenced by the gamma and gamma' volume fractions. A computational thermodynamic modeling tool significantly underpredicted gamma' solvus temperatures and grossly overpredicted the amount of TCP phase at 982 C. Furthermore, the predictions by the software tool for the gamma - gamma' lattice mismatch were typically of the wrong sign and magnitude, but predictions could be improved if TCP formation was suspended within the software program. However, the statistical regression models provided excellent estimations of the microstructural parameters based on bulk alloy composition, thereby demonstrating their usefulness.

  16. Two-step preparation of laser-textured Ni/FTO bilayer composite films with high photoelectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bao-jia, E-mail: li_bjia@126.com [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Jiangsu Provincial Key Laboratory for Science and Technology of Photon Manufacturing, Jiangsu University, Zhenjiang 212013 (China); Huang, Li-jing [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Jiangsu Provincial Key Laboratory for Science and Technology of Photon Manufacturing, Jiangsu University, Zhenjiang 212013 (China); Ren, Nai-fei [Jiangsu Provincial Key Laboratory for Science and Technology of Photon Manufacturing, Jiangsu University, Zhenjiang 212013 (China); School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Kong, Xia; Cai, Yun-long; Zhang, Jie-lu [Jiangsu Tailong Reduction Box Co. Ltd, Taixing 225400 (China)

    2015-08-15

    Highlights: • A two-step strategy was proposed to prepare laser-textured Ni/FTO composite films. • Ni/FTO film with a 10-nm-thick Ni layer (Ni{sub 10}/FTO film) had the best performance. • The Ni{sub 10}/FTO film underwent magnetic-field-assisted and -free laser irradiations. • All the magnetic laser-irradiated (MLI-NF) films were textured and annealed. • The MLI-NF film using a fluence of 1.0 J/cm{sup 2} showed the highest figure of merit. - Abstract: A two-step strategy, i.e. sputtering Ni layers on FTO glass combined with magnetic-field-assisted laser irradiation, was proposed to prepare laser-textured Ni/FTO bilayer composite films. By analyzing surface morphology, crystal structure and photoelectric properties of Ni/FTO films with different Ni layer thicknesses, the Ni/FTO film with a 10-nm-thick Ni layer (Ni{sub 10}/FTO film), which had the best overall photoelectric property, was chosen to undergo magnetic-field-assisted laser irradiation with different laser fluences. Magnetic-field-free laser irradiation of the Ni{sub 10}/FTO film was also carried out for comparison purpose. It was found that magnetic-field-assisted laser irradiation using a fluence of 1.0 J/cm{sup 2} was more effective for simultaneously achieving texturing and annealing, resulting in formation of ideal grating textures and significantly increased grain size. The corresponding film (MLI-NF1.0 film) showed the highest figure of merit of 22.8 × 10{sup −3} Ω{sup −1} compared to 13.1 × 10{sup −3} Ω{sup −1} of the FTO glass and 1.4 × 10{sup −3} Ω{sup −1} of the Ni{sub 10}/FTO film, suggesting that the two-step strategy is excellent for preparing textured Ni/FTO films with high photoelectric properties.

  17. 2.5 D Transrotational Microcrystals and Nanostructures Revealed by TEM in Crystallizing Amorphous Films

    Science.gov (United States)

    Kolosov, Vladimir

    2015-03-01

    Unexpected transrotational microcrystals can be grown in thin 10-100 nm amorphous films. Crystals of different morphology (from nanowhiskers to spherulites, complex textures) and chemical nature (oxides, chalcogenides, metals and alloys) grown in thin films prepared by various methods are studied by transmission electron microscopy (TEM). We use primarily our TEM bend-contour method and SAED (HREM, AFM are also performed). The phenomenon resides in strong (up to 300 degrees/ μm) regular internal bending of crystal lattice planes in a growing crystal. It can be traced inside TEM in situ. Usual translation is complicated by slight regular rotation of the crystal unit cell (transrotation) most prominent at the mesoscale. Different geometries of transrotation of positive and negative curvature are revealed. Transrotational crystal resembles ideal single crystal enclosed in a curved space. It can be also considered similar to hypothetical endless 2.5 D analogy of MW nanotube/nano-onion halves. Transrotation is strongly increasing as the film gets thinner in the range 100-15 nm. Transrotations supplement dislocations and disclinations. New transrotational nanocrystalline model of amorphous state is proposed. Support of Ministry of Higher Education and Science is acknowledged.

  18. Investigation of crystallization and amorphization dynamics of phase-change thin films by subnanosecond laser pulses.

    Science.gov (United States)

    Kieu, Khanh; Narumi, Kenji; Mansuripur, Masud

    2006-10-20

    We report experimental results on amorphization and crystallization dynamics of reversible phase-change (PC) thin-film samples, GeSbTe and GeBiTe, for optical disk data storage. The investigation was conducted with subnanosecond laser pulses using a pump-and-probe configuration. Amorphization of the crystalline films could be achieved with a single subnanosecond laser pulse; the amorphization dynamics follow closely the temperature kinetics induced in the irradiated spot. As for crystallization of the samples initially in the amorphous state, a single subnanosecond pulse was found to be insufficient to fully crystallize the irradiated spot, but we could crystallize the PC film (in the area under the focused spot) by applying multiple short pulses. Our multipulse studies reveal that the GeSbTe crystallization is dominated by the growth of nuclei whose initial formation is slow but, once formed, their subsequent growth (under a sequence of subnanosecond pulses) happens quickly. In the case of GeBiTe samples, the crystalline nuclei appear to be present in the material initially, as they grow immediately upon illumination with laser pulses. Whereas our amorphous GeSbTe samples required approximately 200 pulses for full crystallization, for the GeBiTe samples approximately 15 pulses sufficed.

  19. Nonlinear Analysis of Actuation Performance of Shape Memory Alloy Composite Film Based on Silicon Substrate

    Directory of Open Access Journals (Sweden)

    Shuangshuang Sun

    2014-01-01

    Full Text Available The mechanical model of the shape memory alloy (SMA composite film with silicon (Si substrate was established by the method of mechanics of composite materials. The coupled action between the SMA film and Si substrate under thermal loads was analyzed by combining static equilibrium equations, geometric equations, and physical equations. The material nonlinearity of SMA and the geometric nonlinearity of bending deformation were both considered. By simulating and analyzing the actuation performance of the SMA composite film during one cooling-heating thermal cycle, it is found that the final cooling temperature, boundary condition, and the thickness of SMA film have significant effects on the actuation performance of the SMA composite film. Besides, the maximum deflection of the SMA composite film is affected obviously by the geometric nonlinearity of bending deformation when the thickness of SMA film is very large.

  20. Methanol electrooxidation on Pt particles dispersed into PANI/SWNT composite films

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Gang; Li, Li; Li, Jing-Hong; Xu, Bo-Qing [Innovative Catalysis Program, Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084 (China)

    2006-04-21

    Conducting polymer composite films comprised of polyaniline (PANI) and single wall carbon nanotubes (SWNT) was prepared by electrochemical codeposition during the electropolymerization in an aniline solution with suspending SWNT. The fabricated composite films are assessed with respect to their potential application as support materials in Pt electrocatalyst for electrochemical oxidation of methanol. The PANI/SWNT composite film incorporated with SWNT has a higher polymeric degree and lower defect density in PANI structure than PANI film. Furthermore, the incorporation of SWNT also leads to higher electrochemically accessible surface areas (S{sub a}), electronic conductivity and easier charge-transfer at polymer/electrolyte interfaces, which make higher dispersion and utilization for deposited Pt. Therefore, the Pt particles electrodeposited on PANI/SWNT composite polymer film exhibits excellent catalytic activity and stability for the electrooxidation of methanol in comparison to Pt supported on PANI film, which reveals that the composite film is more promising for application in electrocatalyst as a support material. (author)

  1. Electrochemical deposition of Mg(OH2/GO composite films for corrosion protection of magnesium alloys

    Directory of Open Access Journals (Sweden)

    Fengxia Wu

    2015-09-01

    Full Text Available Mg(OH2/graphene oxide (GO composite film was electrochemical deposited on AZ91D magnesium alloys at constant potential. The characteristics of the Mg(OH2/GO composite film were investigated by scanning electron microscope (SEM, energy-dispersive X-ray spectrometry (EDS, X-ray diffractometer (XRD and Raman spectroscopy. It was shown that the flaky GO randomly distributed in the composite film. Compared with the Mg(OH2 film, the Mg(OH2/GO composite film exhibited more uniform and compact structure. Potentiodynamic polarization tests revealed that the Mg(OH2/GO composite film could significantly improve the corrosion resistance of Mg(OH2 film with an obvious positive shift of corrosion potential by 0.19 V and a dramatic reduction of corrosion current density by more than one order of magnitude.

  2. Two kinds of composite films: Graphene oxide/carbon nanotube film and graphene oxide/activated carbon film via a self-assemble preparation process

    Science.gov (United States)

    Zou, Li-feng; Ma, Nan; Sun, Mei; Ji, Tian-hao

    2014-11-01

    Two kinds of free-standing composite films, including graphene oxide and activated carbon film as well as graphene oxide and carbon nanotube film, were fabricated through a simple suspension mixing and then natural deposition process. The films were characterized by various measurement techniques in detail. The results show that the composite films without any treatment almost still remain the original properties of the corresponding precursors, and exhibit loose structure, which can be easily broken in water; whereas after treated at 200 °C in air, the films become relatively more dense, and even if immersed into concentrated strong alkali or acid for five days, they still keep the film-morphologies, but regretfully, they show obvious brittleness and slight hydrophilicity. As soon as the treated films are performed in high concentrated strong alkali for about one day, their brittleness and wettability can be improved and became good flexibility and complete hydrophilicity.

  3. Application of pyrolysis process to remove and recover liquid crystal and films from waste liquid crystal display glass.

    Science.gov (United States)

    Lu, Rixin; Ma, En; Xu, Zhenming

    2012-12-01

    Liquid crystal display (LCD) glass mainly consists of polarizing film, liquid crystal and glass substrate. Removing and recovering the liquid crystal and films from the LCD glass effectively has important significance for recovering the other parts. This study proposed a pyrolysis process to recover the organic parts from LCD glass. Through thermal gravimetric analysis, the pyrolysis temperature of the LCD glass could be chosen at 850 K. The removal rate of organic parts from LCD glass reached 87.87 wt%. Pyrolysis products consisted of 66.82 wt% oils, 21.01 wt% gaseous and 12.13 wt% residues. In addition, the oils contained 46.27 wt% acetic acid and 32.94 wt% triphenyl phosphate. Then, the pyrolysis mechanisms and products sources of the liquid crystal glass have been analyzed based on the information of bonds energy. The pyrolysis mechanism analysis proved that the products mainly consisted of acetic acid, triphenyl phosphate and C, which is consistent to the results of GC-MS analysis. A reasonable way has been put forward to recycle the pyrolysis products: acetic acid and triphenyl phosphate can be collected by distillation, the rest oils and gases can be used as fuel and the remained glass can be used to extract indium and to produce building materials.

  4. Matrix dependent changes in metachromasy of crystal violet in Langmuir-Blodgett films

    Science.gov (United States)

    Shil, Ashis; Saha, Mitu; Debnath, Chandan; Hussain, S. A.; Bhattacharjee, D.

    2016-11-01

    This communication reports the effect of building matrices and nano clay platelets on the aggregation pattern of a water soluble cationic fluorescent dye Crystal Violet (CV) in Langmuir-Blodgett (LB) Films. When stearic acid (SA) was used as a building matrix, pressure induced changes in metachromasy was observed in the SA-CV complex LB films with a characteristic J-band formed at the longer wavelength side. On the other hand, clay incorporated hybrid LB films showed high degree of control over H-dimeric band. Isotherm characteristics, Brewster Angle Microscopic (BAM) images, UV-vis absorption and fluorescence characteristic studies were employed to investigate this result.

  5. Polyester fabric coated with Ag/ZnO composite film by magnetron sputtering

    Science.gov (United States)

    Yuan, Xiaohong; Xu, Wenzheng; Huang, Fenglin; Chen, Dongsheng; Wei, Qufu

    2016-12-01

    Ag/ZnO composite film was successfully deposited on polyester fabric by using direct current (DC) magnetron sputtering and radio frequency (RF) magnetron reaction sputtering techniques with pure silver (Ag) and zinc (Zn) targets. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to examine the deposited film on the fabric. It was found that the zinc film coated on Ag film before RF reactive sputtering could protect the silver film from oxidation. Anti-ultraviolet property and antistatic property of the coated samples using different magnetron sputtering methods were also investigated. The experimental results showed that Ag film was oxidized into in Ag2O film in high vacuum oxygen environment. The deposition of Zn film on the surface of the fabric coated with Ag film before RF reactive sputtering, could successfully obtained Ag/ZnO composite film, and also generated structural color on the polyester fabric.

  6. Electrical conductivity and crystallization of amorphous bismuth ruthenate thin films deposited by spray pyrolysis.

    Science.gov (United States)

    Ryll, Thomas; Brunner, Andreas; Ellenbroek, Stefan; Bieberle-Hutter, Anja; Rupp, Jennifer L M; Gauckler, Ludwig J

    2010-11-14

    Amorphous oxide thin films with tailored functionality will be crucial for the next generation of micro-electro-mechanical-systems (MEMS). Due to potentially favorable electronic and catalytic properties, amorphous bismuth ruthenate thin films might be applied in this regard. We report on the deposition of amorphous bismuth ruthenate thin films by spray pyrolysis, their crystallization behavior and electrical conductivity. At room temperature the 200 nm thin amorphous films exhibit a high electrical conductivity of 7.7 × 10(4) S m(-1), which was found to be slightly thermally activated (E(a) = 4.1 × 10(-3) eV). It follows that a long-range order of the RuO(6) octahedra is no precondition for the electrical conductivity of Bi(3)Ru(3)O(11). Upon heating to the temperature range between 490 °C and 580 °C the initially amorphous films crystallize rapidly. Simultaneously, a transition from a dense and continuous film to isolated Bi(3)Ru(3)O(11) particles on the substrate takes place. Solid-state agglomeration is proposed as the mechanism responsible for disintegration. The area specific resistance of Bi(3)Ru(3)O(11) particles contacted by Pt paste on gadolinia doped ceria electrolyte pellets was found to be 7 Ω cm(2) at 607 °C in air. Amorphous bismuth ruthenate thin films are proposed for application in electrochemical devices operating at low temperatures, where a high electrical conductivity is required.

  7. Fiber-optic temperature sensor using a liquid crystal film for laser-induced interstitial thermotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Bong-Soo; Tack, Gye-Rae; Chung, Soon-Cheol; Yi, Jeong-Han [Konkuk University, Chungju (Korea, Republic of); Kim, Sin [Cheju National University, Cheju (Korea, Republic of); Cho, Hyo-Sung [Yonsei University, Wonju (Korea, Republic of)

    2005-06-15

    In this paper, we describe the feasibility of developing a new fiber-optic temperature sensor using a thermo-sensitive liquid crystal (LC) film for laser-induced interstitial thermotherapy (LITT). The temperature change in the tissue or the tumor causes the color of the LC film in contacted with the tissue to change, and that change alters the reflectivity of the LC film. The light with a selected wavelength that is transmitted to the LC film and the optical power of the reflected light are measured using transmitting and receiving optical fibers, respectively. Also, the relationship between the temperature and the optical power of reflected light is determined using the characteristics of the LC films.

  8. Mechanism of Crystallization and Implications for Charge Transport in Poly(3-ethylhexylthiophene) Thin Films

    KAUST Repository

    Duong, Duc T.

    2014-04-09

    In this work, crystallization kinetics and aggregate growth of poly(3-ethylhexylthiophene) (P3EHT) thin films are studied as a function of film thickness. X-ray diffraction and optical absorption show that individual aggregates and crystallites grow anisotropically and mostly along only two packing directions: the alkyl stacking and the polymer chain backbone direction. Further, it is also determined that crystallization kinetics is limited by the reorganization of polymer chains and depends strongly on the film thickness and average molecular weight. Time-dependent, field-effect hole mobilities in thin films reveal a percolation threshold for both low and high molecular weight P3EHT. Structural analysis reveals that charge percolation requires bridged aggregates separated by a distance of ≈2-3 nm, which is on the order of the polymer persistence length. These results thus highlight the importance of tie molecules and inter-aggregate distance in supporting charge percolation in semiconducting polymer thin films. The study as a whole also demonstrates that P3EHT is an ideal model system for polythiophenes and should prove to be useful for future investigations into crystallization kinetics. Recrystallization kinetics and its relationship to charge transport in poly(3-ethylhexylthiophene) (P3EHT) thin films are investigated using a combination of grazing incidence X-ray diffraction, optical absorption, and field-effect transistor measurements. These results show that thin film crystallization kinetics is limited by polymer chain reorganization and that charge percolation depends strongly on the edge-to-edge distance between aggregates. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Surface and interface analysis of HAP/TiO2 composite films on Ti6Al4V

    Institute of Scientific and Technical Information of China (English)

    SU Bing; ZHANG Weng-guang; YU Xu-dong; WANG Cheng-tao

    2004-01-01

    The composite films constituted of hydroxyapatite (HAP) submicron particles embedded in the gel composed of the titania nanoparticles were prepared on commercial Ti6Al4V plates with titania buffer layer obtained by a spin-coating technique. The films were annealed in air at 450 ℃, 550 ℃ and 650 ℃, respectively. The phase formation, surface morphology, andinterfacial microstructure of the films were investigated by X-ray diffraction(XRD),Fourier transform infrared spectroscopy (FT-IR), field emission-scanning electron microscopy(FE-SEM) and energy dispersive X-ray (EDS) analysis. The results show that the as-prepared films are all well-crystallized, dense,homogeneous, and there was a close interfacial bond between the film and the substrate. The results of adhesion test indicate that there is a good bonding strength between the film and the substrate. The bone-like apatite formation on the surface of the films after immersion in acellular simulatedbody fluid(SBF) validated their bioactivities.

  10. Optical properties and residual stress in Nb-Si composite films prepared by magnetron cosputtering.

    Science.gov (United States)

    Tang, Chien-Jen; Porter, Glen Andrew; Jaing, Cheng-Chung; Tsai, Fang-Ming

    2015-02-01

    This paper investigates Nb-Si metal composite films with various proportions of niobium in comparison to pure Nb films. Films were prepared by two-target RF-DC magnetron cosputtering deposition. The optical properties and residual stress were analyzed. A composition of Nb(0.74)Si(0.26) was chosen toward the design and fabrication of solar absorbing coatings having a high absorption in a broad wavelength range, a low residual stress, and suitable optical constants. The layer thicknesses and absorption characteristics of the Nb-Si composite films adhere more closely to the design than other coatings made of dielectric film materials.

  11. Tunable Nanostructures and Crystal Structures in Titanium Oxide Films

    Directory of Open Access Journals (Sweden)

    Fuess H

    2008-01-01

    Full Text Available Abstract Controllable nanostructures in spin coated titanium oxide (TiO2 films have been achieved by a very simple means, through change of post deposition annealing temperature. Electron beam imaging and reciprocal space analysis revealed as-deposited TiO2films to be characterized by a dominant anatase phase which converts to the rutile form at 600 °C and reverts to the anatase modification at 1,200 °C. The phase changes are also accompanied by changes in the film microstructure: from regular nanoparticles (as-deposited to nanowires (600 °C and finally to dendrite like shapes at 1,200 °C. Photoluminescence studies, Raman spectral results, and X-ray diffraction data also furnish evidence in support of the observed solid state phase transformations in TiO2.

  12. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification

    OpenAIRE

    Rackel Reis; Dumée, Ludovic F.; Tardy, Blaise L.; Raymond Dagastine; John D. Orbell; Jürg A. Schutz; Duke, Mikel C.

    2016-01-01

    Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membra...

  13. Application of nano-TiO2/LDPE composite film on photocatalytic oxidation degradation of dichloromethane.

    Science.gov (United States)

    Suwannahong, Kowit; Liengcharernsit, Winai; Sanongraj, Wipada; Kruenate, Jittiporn

    2012-09-01

    This study focused on the photocatalytic destruction of dichloromethane (DCM) in indoor air using the nano-TiO2/LDPE composite film as an economical photocatalyst. The nano-TiO2 was dispersed in a polyethylene matrix to form composite film. The photocatalytic activity of the nano-TiO2/LDPE composite films was evaluated through the degradation of dichloromethane(DCM) under UV-C irradiance at specific wavelength of 254 nm. The percentage of nano-TiO2 contents varied from 0, 5, and 10% (wt cat./wt LDPE composite film). The results derived from the kinetic model revealed that the photocatalytic rates of 5 and 10 wt.% nano-TiO2/ LDPE composite films follow the first order reaction while the rate of the film without TiO2 followed the zero order reaction. At low concentration of DCM, the rate of photocatalytic degradation of the DCM was slower than that at high DCM concentration. The 10 wt.% of TiO2 content of the nano-TiO2/LDPE composite film yielded the highest degradation efficiency of 78%, followed by the removal efficiency of 55% for the 5 wt.% of TiO2 content of the nano-TiO2/LDPE composite film. In contrast with the composite film containing nano-TiO2, the LDPE film without adding nano-TiO2 expressed the degradation efficiency of 28%.

  14. Effect of annealing ambient on anisotropic retraction of film edges during solid-state dewetting of thin single crystal films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gye Hyun; Thompson, Carl V., E-mail: cthomp@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239 (United States); Ma, Wen [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239 (United States); Yildiz, Bilge [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239 (United States); Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239 (United States)

    2016-08-21

    During solid-state dewetting of thin single crystal films, film edges retract at a rate that is strongly dependent on their crystallographic orientations. Edges with kinetically stable in-plane orientations remain straight as they retract, while those with other in-plane orientations develop in-plane facets as they retract. Kinetically stable edges have retraction rates that are lower than edges with other orientations and thus determine the shape of the natural holes that form during solid-state dewetting. In this paper, measurements of the retraction rates of kinetically stable edges for single crystal (110) and (100) Ni films on MgO are presented. Relative retraction rates of kinetically stable edges with different crystallographic orientations are observed to change under different annealing conditions, and this accordingly changes the initial shapes of growing holes. The surfaces of (110) and (100) films were also characterized using low energy electron diffraction, and different surface reconstructions were observed under different ambient conditions. The observed surface structures were found to correlate with the observed changes in the relative retraction rates of the kinetically stable edges.

  15. Calculation of the Point Defects Ensemble in Zinc Sulfide Single Crystals and Films

    Directory of Open Access Journals (Sweden)

    D.I. Kurbatov

    2012-11-01

    Full Text Available In work calculation of concentration of the neutral and charged point defects, positions of Fermi level and free charge carriers in zinc sulfide single crystals and films depending on their condensation conditions was carried out. For calculations used the experimentally found energy levels of defects in ZnS band gap.

  16. Modulated photonic-crystal structures as broadband back reflectors in thin-film solar cells

    NARCIS (Netherlands)

    Krc, J.; Zeman, M.; Luxembourg, S.L.; Topic, M.

    2009-01-01

    A concept of a modulated one-dimensional photonic-crystal (PC) structure is introduced as a back reflector for thin-film solar cells. The structure comprises two PC parts, each consisting of layers of different thicknesses. Using layers of amorphous silicon and amorphous silicon nitride a reflectanc

  17. Calculation of the Point Defects Ensemble in Zinc Sulfide Single Crystals and Films

    OpenAIRE

    D.I. Kurbatov

    2012-01-01

    In work calculation of concentration of the neutral and charged point defects, positions of Fermi level and free charge carriers in zinc sulfide single crystals and films depending on their condensation conditions was carried out. For calculations used the experimentally found energy levels of defects in ZnS band gap.

  18. Hierarchical pattern formation through photo-induced disorder in block copolymer/additive composite films

    Science.gov (United States)

    Yao, Li; Watkins, James

    2013-03-01

    Segregation strength in hybrid materials can be increased through selective hydrogen bonding between organic or nanoparticle additives and one block of weakly segregated block copolymers to generate well ordered hybrid materials. Here, we report the use of enantiopure tartaric acid as the additive to dramatically improve ordering in poly(ethylene oxide-block-tert-butyl acrylate) (PEO-b-PtBA) copolymers. Phase behavior and morphologies within both bulk and thin films were studied by TEM, AFM and X-ray scattering. Suppression of PEO crystallization by the interaction between tartaric acid and the PEO block enables the formation of well ordered smooth thin films. With the addition of a photo acid generator, photo-induced disorder in PEO-b-PtBA/tartaric acid composite system can be achieved upon UV exposure to deprotect PtBA block to yield poly(acrylic acid) (PAA), which is phase-miscible with PEO. Due to the strong interaction of tartaric acid with both blocks, the system undergoes a disordering transition within seconds during a post-exposure baking. With the assistance of trace-amounts of base quencher, high resolution, hierarchical patterns of sub-micron regions of ordered and disordered domains were achieved in thin films through area-selective UV exposure using a photo-mask. Funding from Center for Hierarchical Manufacturing (CHM); Facility support from Materials Research Science and Engineering Center at UMass Amherst and Cornell High Energy Synchrotron Source

  19. Effects of Excess Cu Addition on Photochromic Properties of AgCl-Urethane Resin Composite Films

    Directory of Open Access Journals (Sweden)

    Hidetoshi Miyazaki

    2013-01-01

    Full Text Available AgCl-resin photochromic composite films were prepared using AgNO3, HCl-EtOH, CuCl2 ethanol solutions, and a urethane resin as starting materials. The AgCl particle size in the composite films, which was confirmed via TEM observations, was 23–43 nm. The AgCl composite films showed photochromic properties: coloring induced by UV-vis irradiation and bleaching induced by cessation of UV-vis irradiation. The coloring and bleaching speed of the composite film increases with increasing CuCl2 mixing ratio.

  20. Polyaniline/polysulfone composite film electrode for simultaneous determination of hydroquinone and catechol

    Energy Technology Data Exchange (ETDEWEB)

    Feng Xiaojuan, E-mail: fengxiaojuan820@yahoo.cn [Chemistry Department of HeXi University, Zhangye 734000 (China); Shi Yanlong [Chemistry Department of HeXi University, Zhangye 734000 (China); Hu Zhongai [Key Laboratory of Polymer, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We prepared a composite film which has bi-layers with asymmetric microstructure and relatively rich porosity which provides larger surface area for electrochemical reaction. Black-Right-Pointing-Pointer The outer polysulfone layer is propitious for the organic molecules to enrich on the composite film, which brings great enhancement in electron transfer kinetics. Black-Right-Pointing-Pointer The composite film electrode can be used to detect qualitatively or quantitatively hydroquinone and catechol in the single solute or mixed systems. - Abstract: Polyaniline (PAN)/polysulfone (PSF) composite film electrodes were successfully prepared by electropolymerization using cyclic votammetry technique. The composite film electrodes show a great enhancement in electron transfer kinetics, and the separation between oxidation and reduction peaks ({Delta}E{sub p}) decreases from 200 to 35 mV for hydroquinone (H{sub 2}Q) and from 275 to 42 mV for catechol (CC) at bare Pt and composite film electrodes respectively. In their mixed systems, the redox peak of H{sub 2}Q and two pairs of redox peaks of CC on this composite film electrode could be obviously distinguished which indicates the composite film electrodes have excellent electrocatalytic activity and reversibility towards the oxidation of two diphenols (hydroquinone and catechol). The linear relationships between the peak current and concentration are observed for single solute and mixed systems within the certain concentration range, implying that the composite film electrodes have potential application in the qualitative or quantitative analysis of diphenol.

  1. Dynamics of metal-induced crystallization of ultrathin Ge films by rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Yuanxun; Huang, Shujuan; Shrestha, Santosh; Conibeer, Gavin [School of Photovoltaic and Renewable Energy Engineering, UNSW Australia, Sydney 2052 (Australia)

    2015-12-07

    Though Ge crystallization has been widely studied, few works investigate metal-induced crystallization of ultrathin Ge films. For 2 nm Ge films in oxide matrix, crystallization becomes challenging due to easy oxidation and low mobility of Ge atoms. Introducing metal atoms may alleviate these problems, but the functions and the behaviours of metal atoms need to be clarified. This paper investigates the crystallization dynamics of a multilayer structure 1.9 nm Ge/0.5 nm Al/1.5 nm Al{sub 2}O{sub 3} under rapid thermal annealing (RTA). The functions of metal atoms, like effective anti-oxidation, downshifting Raman peaks, and incapability to decrease crystallization temperature, are found and explained. The metal behaviours, such as inter-diffusion and defect generation, are supported with direct evidences, Al-Ge nanobicrystals, and Al cluster in Ge atoms. With these understandings, a two-step RTA process achieves high-quality 2 nm nanocrystal Ge films with Raman peak at 298 cm{sup −1} of FWHM 10.3 cm{sup −1} and atomic smooth interfaces.

  2. Non-classical crystallization of thin films and nanostructures in CVD and PVD processes

    CERN Document Server

    Hwang, Nong Moon

    2016-01-01

    This book provides a comprehensive introduction to a recently-developed approach to the growth mechanism of thin films and nanostructures via chemical vapour deposition (CVD). Starting from the underlying principles of the low pressure synthesis of diamond films, it is shown that diamond growth occurs not by individual atoms but by charged nanoparticles. This newly-discovered growth mechanism turns out to be general to many CVD and some physical vapor deposition (PVD) processes. This non-classical crystallization is a new paradigm of crystal growth, with active research taking place on growth in solution, especially in biomineralization processes. Established understanding of the growth of thin films and nanostructures is based around processes involving individual atoms or molecules. According to the author’s research over the last two decades, however, the generation of charged gas phase nuclei is shown to be the rule rather than the exception in the CVD process, and charged gas phase nuclei are actively ...

  3. Nanodiamond-polymer nanoparticle composites and their thin films

    Science.gov (United States)

    Attia, N. F.; Rao, J. P.; Geckeler, K. E.

    2014-04-01

    Nanodiamonds obtained from detonation processes have received a great deal of attention during the past decades because of their unique properties and applications. The dispersion of nanodiamond particles can be achieved by different methods including the use of polymer nanoparticles. Here, we describe the dispersion of nanodiamonds in conjunction with sonication using poly(vinylpyrrolidone) nanoparticles with a particle size range of 23.3-61.3 nm, providing a good, economic, and efficient method for the dispersion. The average particle size was found to be 37.5 nm, as confirmed by transmission electron microscopy. The interaction between the nanodiamonds and polymer nanoparticles was characterized by FTIR spectroscopy and the effect of the polymer nanoparticle concentration, sonication time, and frequency on the dispersion process of nanodiamonds is highlighted. In addition, we prepared thin films of nanodiamond-polymer composites with different nanodiamond contents that showed good nanodiamond dispersion. The thin film can act as a UV filter and is transparent in the visible region. The thin films of nanodiamond-poly(vinylpyrrolidone) nanoparticles were characterized by SEM and UV-Vis spectroscopy.

  4. Crystallization study of SrTiO3 thin films prepared by dip coating

    Directory of Open Access Journals (Sweden)

    Edson R. Leite

    1999-04-01

    Full Text Available In this study, the crystallization process of SrTiO3 thin films, prepared by a chemical method, was characterized by Fourier Transformed Infra Red (FT-IR, Grazing Incident X-ray Diffraction (GIXRD, Thermal Analysis (TG and X-ray Absorption Near Edge Structure (XANES. The results showed that an amorphous inorganic phase is formed, consisting of clusters of oxygen five-coordinate titanium. The amorphous phase begins crystallizing at temperatures above 450 °C. No intermediate crystalline phase and no preferential orientation was observed for films deposited on MgO (100. FT-IR results suggest the presence of the carbonate group. However, the low thermal stability of this group and the low crystallization temperature of the observed SrTiO3 phase indicate that this carbonate is adsorbed.

  5. Compositional analysis of silicon oxide/silicon nitride thin films

    Directory of Open Access Journals (Sweden)

    Meziani Samir

    2016-06-01

    Full Text Available Hydrogen, amorphous silicon nitride (SiNx:H abbreviated SiNx films were grown on multicrystalline silicon (mc-Si substrate by plasma enhanced chemical vapour deposition (PECVD in parallel configuration using NH3/SiH4 gas mixtures. The mc-Si wafers were taken from the same column of Si cast ingot. After the deposition process, the layers were oxidized (thermal oxidation in dry oxygen ambient environment at 950 °C to get oxide/nitride (ON structure. Secondary ion mass spectroscopy (SIMS, Rutherford backscattering spectroscopy (RBS, Auger electron spectroscopy (AES and energy dispersive X-ray analysis (EDX were employed for analyzing quantitatively the chemical composition and stoichiometry in the oxide-nitride stacked films. The effect of annealing temperature on the chemical composition of ON structure has been investigated. Some species, O, N, Si were redistributed in this structure during the thermal oxidation of SiNx. Indeed, oxygen diffused to the nitride layer into Si2O2N during dry oxidation.

  6. Preparation and Characterization of InAs/Si Composite Film

    Institute of Scientific and Technical Information of China (English)

    YANG Lin; LI Guang-Hai; ZHENG Mao-Jun; ZHANG Li-De

    2000-01-01

    Composite thin films consisting of nanosized InAs particles embedded in amorphous Si matrices were prepared by radio frequency co-sputtering of InAs and Si. X-ray diffraction spectra show that the particle size of InAs increases with the increasing annealing temperature, while the particle sizes of In and As reach their maximum values at the temperature of 200℃, and decrease with the further increase of the annealing temperature. In and As can not exist in the 500℃ sample due to the sublimation of In and As and the reaction In+As→InAs. The composition of the film in different levels was analyzed. We found that only in the deep level, the mole contents of As and In conform to the stoichiometric ratio and the oxidation occurs only a few nanometers from the surface. We believe that the scarcity of In and As near the surface is due to the sublimation of In and the oxide of As.

  7. Crystallographic and magnetostriction properties of Fe and FeB-alloy thin films formed on MgO(100 single-crystal substrates

    Directory of Open Access Journals (Sweden)

    Ohtake M.

    2013-01-01

    Full Text Available Fe(100bcc single-crystal film, Fe-B amorphous film, and Fe-B film consisting of a mixture of epitaxial bcc(100 crystal and amorphous are prepared on MgO(100 single-crystal substrates. The influence of crystallographic property on the magnetostriction behavior under rotating magnetic fields is investigated. The output waveform of magnetostriction is sinusoidal for the amorphous film, whereas that of single-crystal film shows a triangle shape. 90° magnetic domain walls are observed for the single-crystal Fe film and the film shows a four-fold symmetry in in-plane magnetic anisotropy. The observation of triangle waveforms is related to the domain wall motion in magnetically unsaturated Fe(100bcc film under rotating magnetic fields. A distortion from triangle wave is observed for the Fe-B film consisting of a mixture of bcc-crystal and amorphous. The magnetostriction behavior is influenced by the magnetization structure.

  8. Anomalous Hall effects in pseudo-single-crystal γ'-Fe4N thin films

    Science.gov (United States)

    Kabara, Kazuki; Tsunoda, Masakiyo; Kokado, Satoshi

    2016-05-01

    The anomalous Hall effects (AHE) were investigated at various temperatures for the pseudo-single-crystal Fe4N films, deposited on MgO substrates with changing the degree of order (S) of the nitrogen site. Both the anomalous Hall resistivity and the longitudinal resistivity simply decrease with lowering temperature for all the specimens. The AHE of the Fe4N films is presumed to arise from an intrinsic mechanism because of the relationship between the anomalous Hall resistivity and longitudinal resistivity. The anomalous Hall conductivity, σAH, exhibits a specific behavior at low temperature. In the case of the film with S = 0.93, the σAH drastically drops below 50 K, while it simply increases with lowering temperature in the range of 50-300 K. This low-temperature anomaly decays with decreasing S of the film and nearly vanishes in the films with low S. The threshold temperature and the dependence on S of the low-temperature anomaly of the σAH well correspond to those of the anisotropic magnetoresistance effects in the Fe4N films, reported in the literatures. From these results, it is suggested that the low-temperature anomaly of the σAH originates from the crystal field effect which reflects the structural transformation from a cubic to a tetragonal symmetry below 50 K and provides a modulation of the orbital angular momentum of the 3d orbitals at the Fermi level.

  9. Material properties of pulsed-laser crystallized Si thin films grown on yttria-stabilized zirconia crystallization-induction layers by two-step irradiation method

    Science.gov (United States)

    Thi Kieu Lien, Mai; Horita, Susumu

    2016-03-01

    Amorphous Si thin films on yttria-stabilized zirconia (YSZ) layers were crystallized widely in solid phase by the two-step method with a pulsed laser, moving the sample stage. The crystalline quality, impurity diffusion, and electrical properties of the crystallized Si films were investigated. It was found that the crystallinity of the Si thin films was improved and their surface was smooth without an incubation layer at the interface, indicating the uniform crystallinity of Si on YSZ. The diffusion of Zr and Y into the Si thin films was as small as or smaller than the order of 1017 atoms/cm3. We evaluated the electrical properties of carrier concentration and Hall mobility of the Si thin films with/without YSZ layers by using the resistivity and AC Hall effect measurements. The temperature and doping concentration dependences were measured for both undoped and P-doped films. It was found that both the undoped and P-doped Si/YSZ/glass films showed higher mobilities and carrier concentrations (and therefore higher conductivities), which indicate a smaller number of defects, than the Si/glass films. This suggested that the Si film crystallized on the YSZ layer is more suitable for application to electronic devices than the Si film on glass.

  10. Selected area laser-crystallized polycrystalline silicon thin films by a pulsed Nd:YAG laser with 355 nm wavelength

    Institute of Scientific and Technical Information of China (English)

    Duan Chunyan; Liu Chao; Ai Bin; Lai Jianjun; Deng Youjun; Shen Hui

    2011-01-01

    Selected area laser-crystallized polycrystalline silicon(p-Si)thin films were prepared by the third harmonics(355 nm wavelength)generated by a solid-state pulsed Nd:YAG laser.Surface morphologies of 400 nm thick films after laser irradiation were analyzed.Raman spectra show that film crystallinity is improved with increase of laser energy.The optimum laser energy density is sensitive to the film thickness.The laser energy density for efficiently crystallizing amorphous silicon films is between 440-634 mJ/cm2 for 300 nm thick films and between 777-993 mJ/cm2 for 400 nm thick films.The optimized laser energy density is 634,975 and 1571 mJ/cm2 for 300,400 and 500 nm thick films,respectively.

  11. Cellulose nanofibrils improve the properties of all-cellulose composites by the nano-reinforcement mechanism and nanofibril-induced crystallization

    Science.gov (United States)

    Yang, Quanling; Saito, Tsuguyuki; Berglund, Lars A.; Isogai, Akira

    2015-10-01

    All-cellulose nanocomposite films containing crystalline TEMPO-oxidized cellulose nanofibrils (TOCNs) of 0-1 wt% were fabricated by mixing aqueous TOCN dispersions with alkali/urea/cellulose (AUC) solutions at room temperature. The mixtures were cast on glass plates, soaked in an acid solution, and the regenerated gel-like films were washed with water and then dried. The TOCN did not form agglomerates in the composites, and had the structure of TOCN-COOH, forming hydrogen bonds with the hydroxyl groups of the regenerated cellulose molecules. X-ray diffraction analysis revealed that the matrix cellulose molecules increased the cellulose II crystal size upon incorporation of TOCN. As a result, the TOCN/AUC composite films had high Young's modulus, tensile strength, thermal stability and oxygen-barrier properties. The TOCN/AUC composite films are promising all-cellulose nanocomposites for versatile applications as new bio-based materials.All-cellulose nanocomposite films containing crystalline TEMPO-oxidized cellulose nanofibrils (TOCNs) of 0-1 wt% were fabricated by mixing aqueous TOCN dispersions with alkali/urea/cellulose (AUC) solutions at room temperature. The mixtures were cast on glass plates, soaked in an acid solution, and the regenerated gel-like films were washed with water and then dried. The TOCN did not form agglomerates in the composites, and had the structure of TOCN-COOH, forming hydrogen bonds with the hydroxyl groups of the regenerated cellulose molecules. X-ray diffraction analysis revealed that the matrix cellulose molecules increased the cellulose II crystal size upon incorporation of TOCN. As a result, the TOCN/AUC composite films had high Young's modulus, tensile strength, thermal stability and oxygen-barrier properties. The TOCN/AUC composite films are promising all-cellulose nanocomposites for versatile applications as new bio-based materials. Electronic supplementary information (ESI) available: Fig. S1-S3 show an AFM image of TOCN, SEM

  12. Swift heavy ion irradiation induced phase transformation in undoped and niobium doped titanium dioxide composite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Subodh K., E-mail: subodhkgtm@gmail.com [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Chettah, Abdelhak [LGMM Laboratory, Université 20 Août 1955-Skikda, BP 26, 21000 Skikda (Algeria); Singh, R.G. [Department of Physics, Bhagini Nivedita College, Delhi University, Delhi 110043 (India); Ojha, Sunil; Singh, Fouran [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

    2016-07-15

    Study reports the effect of swift heavy ion (SHI) irradiation induced phase transformation in undoped and Niobium doped anatase TiO{sub 2} composite thin films. Investigations were carried out at different densities of electronic excitations (EEs) using 120 MeV Ag and 130 MeV Ni ions irradiations. Films were initially annealed at 900 °C and results revealed that undoped films were highly stable in anatase phase, while the Nb doped films showed the composite nature with the weak presence of Niobium penta-oxide (Nb{sub 2}O{sub 5}) phase. The effect at low density of EEs in undoped film show partial anatase to rutile phase transformation; however doped film shows only further growth of Nb{sub 2}O{sub 5} phase beside the anatase to rutile phase transformation. At higher density of EEs induced by Ag ions, registered continuous ion track of ∼3 nm in lattice which leads to nano-crystallization followed by decomposition/amorphization of rutile TiO{sub 2} and Nb{sub 2}O{sub 5} phases in undoped and doped films, respectively. However, Ni ions are only induced discontinuous sequence of ion tracks with creation of damage and disorder and do not show amorphization in the lattice. The in-elastic thermal spike calculations were carried out for anatase TiO{sub 2} phase to understand the effect of EEs on anatase to rutile phase transformation followed by amorphization in NTO films in terms of continuous and discontinuous track formation by SHI irradiation.

  13. Study on photocatalytic performance of cerium-graphene oxide-titanium dioxide composite film for formaldehyde removal

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jia; Zhang, Quan [The Civil Engineering College of Hunan University, Changsha (China); Lai, Alvin C.K. [Department of Civil and Architectural Engineering, City University of Hong Kong, Kowloon (China); Zeng, Liping [Department of Building Engineering of Hunan Institute of Engineering, Xiangtan (China)

    2016-12-15

    In order to degrade in-car formaldehyde gas, graphene oxide (GO), cerium (Ce), and TiO{sub 2} were organically combined by one-step sol-gel method. Then the mixed collosol was coated onto the surface of inorganic glass substrates to form Ce-GO-TiO{sub 2} composite film by way of immersion, coating, and calcinations. The morphology and crystal structure of as-prepared Ce-GO-TiO{sub 2} film were studied by a series of detection techniques. The photocatalytic performance of this film was analyzed by the degradation effect of formaldehyde under simulated sunlight. The results showed that the Ce-GO-TiO{sub 2} film had the inbuilt mesoporous structure in the lamellar stacking with particles. When the doping amount of Ce and GO were 0.4 and 0.2% (mass ratio), the composite film can improve effectively the response to the visible light and its degradation rate for low concentration of formaldehyde was up to 83.8% in simulated sunlight for 7 h, which could be attributed to the co-function of Ce and GO. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Characterization of whey protein-carboxymethylated chitosan composite films with and without transglutaminase treatment.

    Science.gov (United States)

    Jiang, Shu-Juan; Zhang, Xuan; Ma, Ying; Tuo, Yanfeng; Qian, Fang; Fu, Wenjia; Mu, Guangqing

    2016-11-20

    Edible composite packaging has the advantage of complementary functional properties over its each bio-components. However, reports on whey protein concentrates (WPC)-carboxymethylated chitosan (CMC) composite films have not yet been released. To investigate the preparation of WPC-CMC composite films and its functional properties, four types of WPC-CMC composite films were prepared with and without Transglutaminase (TGase) treatment by mixing WPC aqueous solutions (10%, w/v) with CMC aqueous solutions (3%, w/v) at WPC to CMC volume ratios of (100:0), (75:25), (50:50), and (25:75). SDS-PAGE confirmed that TGase catalyzed crosslinking of whey protein. Results revealed that CMC incorporation conferred a smooth and even surface microstructure on the films and markedly improved the transparency, water barrier properties, mechanical properties and solubility of the composite film. Furthermore, TGase resulted in an improvement in the water vapor barrier properties and mechanical properties of WPC-CMC (75:25 and 50:50, v/v) composite films, and there was no impairment of thermal stability of composite films. Therefore, TGase successfully facilitated the formation of WPC-CMC composite films with some improved functional properties. This offers potential applications as an alternative approach to the preparation of edible packaging films.

  15. The response of quartz crystals coated with thin fatty acid film to organic gases

    CERN Document Server

    Jin, C N; Kim, K H; Kwon, Y S

    1999-01-01

    We tried to apply a quartz crystal as a sensor by using the resonant frequency and the resistance properties of quartz crystals. Four kinds of fatty acids that have the same head groups were coated on the surfaces of the quartz crystals, and the shift of the resonant frequency and the resistance were observed based on the lengths of the tail groups. Myristic acid (C sub 1 sub 4), palmitic acid (C sub 1 sub 6), stearic acid (C sub 1 sub 8), and arachidic acid (C sub 2 sub 0) were deposited on the surfaces of quartz crystals by using the Langmuir-Blodgett (LB) method. As a result, the resonant frequency change was more sensitive to high molecular-weight fatty acids than to low molecular-weight ones. We also observed the effect of temperature on stearic acid LB films, and the response properties of quartz crystals coated with stearic-acid LB films to organic gases were investigated. As a result, the sensitivity of quartz crystals to organic gases was higher for higher molecular-weight gas, and we found that quar...

  16. Silver nanowire composite thin films as transparent electrodes for Cu(In,Ga)Se₂/ZnS thin film solar cells.

    Science.gov (United States)

    Tan, Xiao-Hui; Chen, Yu; Liu, Ye-Xiang

    2014-05-20

    Solution processed silver nanowire indium-tin oxide nanoparticle (AgNW-ITONP) composite thin films were successfully applied as the transparent electrodes for Cu(In,Ga)Se₂ (CIGS) thin film solar cells with ZnS buffer layers. Properties of the AgNW-ITONP thin film and its effects on performance of CIGS/ZnS thin film solar cells were studied. Compared with the traditional sputtered ITO electrodes, the AgNW-ITONP thin films show comparable optical transmittance and electrical conductivity. Furthermore, the AgNW-ITONP thin film causes no physical damage to the adjacent surface layer and does not need high temperature annealing, which makes it very suitable to use as transparent conductive layers for heat or sputtering damage-sensitive optoelectronic devices. By using AgNW-ITONP electrodes, the required thickness of the ZnS buffer layers for CIGS thin film solar cells was greatly decreased.

  17. Shape-alterable and -recoverable graphene/polyurethane bi-layered composite film for supercapacitor electrode

    Science.gov (United States)

    Tai, Zhixin; Yan, Xingbin; Xue, Qunji

    2012-09-01

    In this paper, a graphene/shape-memory polyurethane (PU) composite film, used for a supercapacitor electrode, is fabricated by a simple bonding method. In the composite, formerly prepared graphene paper is closely bonded on the surface of the PU slice, forming a bi-layered composite film. Based on the good flexibility of graphene paper and the outstanding shape holding capacity of PU phase, the resulting composite film can be changed into various shapes. Also, the composite film shows excellent shape recovery ability. The graphene/PU composite film used as the electrode maintains a satisfactory electrochemical capacitance of graphene material and there is no decay in the specific capacitance after long-cycle testing, making it attractive for novel supercapacitors with special shapes and shape-memory ability.

  18. Characterization of nanostructured photosensitive (NiS){sub x}(CdS){sub (1-x)} composite thin films grown by successive ionic layer adsorption and reaction (SILAR) route

    Energy Technology Data Exchange (ETDEWEB)

    Ubale, A.U., E-mail: ashokuu@yahoo.com [Nanostructured Thin Film Materials Laboratory, Department of Physics, Govt. Vidarbha Institute of Science and Humanities, Amravati 444604, Maharashtra (India); Bargal, A.N. [Nanostructured Thin Film Materials Laboratory, Department of Physics, Govt. Vidarbha Institute of Science and Humanities, Amravati 444604, Maharashtra (India)

    2011-07-15

    Highlights: {yields} Thin films of (NiS){sub x}(CdS){sub (1-x)} with variable composition (x = 1 to 0) were deposited onto glass substrates by the successive ionic layer adsorption and reaction (SILAR) method. {yields} The structural, surface morphological and electrical characterizations of the as deposited and annealed films were studied. {yields} The bandgap and activation energy of annealed (NiS){sub x}(CdS){sub (1-x)} film decrease with improvement in photosensitive nature. -- Abstract: Recently ternary semiconductor nanostructured composite materials have attracted the interest of researchers because of their photovoltaic applications. Thin films of (NiS){sub x}(CdS){sub (1-x)} with variable composition (x = 1-0) had been deposited onto glass substrates by the successive ionic layer adsorption and reaction (SILAR) method. As grown and annealed films were characterised by X-ray diffraction, scanning electron microscopy and EDAX to investigate structural and morphological properties. The (NiS){sub x}(CdS){sub (1-x)} films were polycrystalline in nature having mixed phase of rhombohedral and hexagonal crystal structure due to NiS and CdS respectively. The optical and electrical properties of (NiS){sub x}(CdS){sub (1-x)} thin films were studied to determine compsition dependent bandgap, activation energy and photconductivity. The bandgap and activation energy of annealed (NiS){sub x}(CdS){sub (1-x)} film decrease with improvement in photosensitive nature.

  19. Monolithic Pellets, Composites and Thick Films of Hydroxyapatite: Correlation of Mechanical Properties with Microstructure.

    Science.gov (United States)

    Wang, Pauchiu Either

    Hydroxyapatite Ca_{10}(PO _4)_6(OH)_2 (abbreviated as HA) has great biocompatibility. Poor mechanical properties of HA implants and decomposition of HA during processing are the major obstacles for widespread uses of HA. In the present thesis we have attempted to understand the sintering behavior of monolithic HA and metal-reinforced HA-matrix composites, and the mechanism of formation of HA coating in the solutions at the normal temperature. The powders of two calcium phosphates, namely hydroxyapatite and dicalcium phosphate (DCP: chemical formula Ca_2P_2O_7), were sintered at various temperatures and in various environments. The density, flexural strength and knoop hardness of both phosphates sintered in air for 4 h initially increased with the sintering temperature, reaching maxima at around 1000-1150 ^circC, and then decreased due to decomposition. To reduce dehydroxylation, HA powder was sintered in moisture at various temperatures up to 1350^circ C and X-ray diffraction study did not indicate any decomposition at the highest sintering temperature. It is seen that dehydroxylation did not hinder sintering, but decomposition obstructed sintering of both HA and DCP. Ductile-phase reinforcement of hydroxyapatite was achieved by addition of silver particulates (5-30 vol.%) in HA powder compacts. A composite made by sintering 10 vol.% Ag and balance HA at 1200^circ C for 1 h in air had flexural strength of 75 +/- 7 MPa, which was almost double that of pure HA sintered under an identical condition. Silver in the composite melted during sintering, but due to poor wetting, did not spread in between HA particles. The increase in the flexural strength of the composites was thought to be due to crack-bridging and crack-arrest by silver inclusions. Thick films (several μm) of hydroxyapatite were deposited on silicon single crystal placed in close proximity to a plate of apatite- and wollastonite -containing glass and dipped into a simulated body fluid (SBF) at 36^circ

  20. Surface Impedance Measurements of Single Crystal MgB2 Films for Radiofrequency Superconductivity Applications

    Energy Technology Data Exchange (ETDEWEB)

    Binping Xiao, Xin Zhao, Joshua Spradlin, Charles Reece, Michael Kelley, Teng Tan, Xi Xiaoxing

    2012-07-01

    We report microstructure analyses and superconducting radiofrequency (SRF) measurements of large scale epitaxial MgB{sub 2} films. MgB{sub 2} films on 5 cm dia. sapphire disks were fabricated by a Hybrid Physical Chemical Vapor Deposition (HPCVD) technique. The electron-beam backscattering diffraction (EBSD) results suggest that the film is a single crystal complying with a MgB{sub 2}(0001) {parallel} Al{sub 2}O{sub 3}(0001) epitaxial relationship. The SRF properties of different film thicknesses (200 nm and 350 nm) were evaluated under different temperatures and applied fields at 7.4 GHz. A surface resistance of 9 {+-} 2 {mu}{Omega} has been observed at 2.2 K.

  1. Growth and characterization of cubic SiC single-crystal films on Si

    Science.gov (United States)

    Powell, J. Anthony; Matus, L. G.; Kuczmarski, Maria A.

    1987-01-01

    Morphological and electrical characterization results are presented for cubic SiC films grown by chemical vapor deposition on single-crystal Si substrates. The films, up to 40 microns thick, were characterized by optical microscopy, (SEM), (TEM), electron channeling, surface profilometry, and Hall measurements. A variety of morphological features observed on the SiC films are described. Electrical measurements showed a decrease in the electron mobility with increasing electron carrier concentration, similar to that observed in Si. Room-temperature electron mobilities up to 520 sq cm/V-s (at an electron carrier concentration of 5 x 10 to the 16th/cu cm) were measured. Finally, a number of parameters believed to be important in the growth process were investigated, and some discussion is given of their possible effects on the film characteristics.

  2. Crystallization Behavior of Anatase Films in Applied Electric Field Heating Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this research the TiO2 thin films were prepared by sol-gel dip coating. The crystallization of the films in the applied electric field heating process was thoroughly studied by many technique, differential thermal analysis (DTA), Raman spectroscopy and atomic force microscope (AFM). Furthermore the phase formation, microstructure and photo-catalytic activity of TiO2 film were studied under the condition of an electric field heating-treatment. It is found that the existence of applied electric field promotes the phase transformation from anatase to rutile. Studies on photo-catalytic degradation show that the photo-catalytic activity of TiO2 thin films in an applied electric field is higher.

  3. Deposition and characterization of silicon thin-films by aluminum-induced crystallization

    Science.gov (United States)

    Ebil, Ozgenc

    Polycrystalline silicon (poly-Si) as a thin-film solar cell material could have major advantages compared to non-silicon thin-film technologies. In theory, thin-film poly-Si may retain the performance and stability of c-Si while taking advantage of established manufacturing techniques. However, poly-Si films deposited onto foreign substrates at low temperatures typically have an average grain size of 10--50 nm. Such a grain structure presents a potential problem for device performance since it introduces an excessive number of grain boundaries which, if left unpassivated, lead to poor solar cell properties. Therefore, for optimum device performance, the grain size of the poly-Si film should be at least comparable to the thickness of the films. For this project, the objectives were the deposition of poly-Si thin-films with 2--5 mum grain size on glass substrates using in-situ and conventional aluminum-induced crystallization (AIC) and the development of a model for AIC process. In-situ AIC experiments were performed using Hot-Wire Chemical Vapor Deposition (HWCVD) both above and below the eutectic temperature (577°C) of Si-Al binary system. Conventional AIC experiments were performed using a-Si layers deposited on aluminum coated glass substrates by Electron-beam deposition, Plasma Enhanced Chemical Vapor Deposition (PECVD) and HWCVD. Continuous poly-Si films with an average grain size of 10 mum on glass substrates were achieved by both in-situ and conventional aluminum-induced crystallization of Si below eutectic temperature. The grain size was determined by three factors; the grain structure of Al layer, the nature of the interfacial oxide, and crystallization temperature. The interface oxide was found to be crucial for AIC process but not necessary for crystallization itself. The characterization of interfacial oxide layer formed on Al films revealed a bilayer structure containing Al2O3 and Al(OH)3 . The effective activation energy for AIC process was determined

  4. Functional chitosan-based grapefruit seed extract composite films for applications in food packaging technology

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Y.M. [Department of Mechanical Engineering, National University of Singapore (Singapore); Lim, S.H.; Tay, B.Y. [Forming Technology Group, Singapore Institute of Manufacturing Technology (Singapore); Lee, M.W. [Food Innovation and Resource Centre, Singapore Polytechnic (Singapore); Thian, E.S., E-mail: mpetes@nus.edu.sg [Department of Mechanical Engineering, National University of Singapore (Singapore)

    2015-09-15

    Highlights: • Chitosan-based grapefruit seed extract (GFSE) films were solution casted. • GFSE was uniformly dispersed within all chitosan film matrices. • All chitosan-based composite films showed remarkable transparency. • Increasing amounts of GFSE incorporated increased the elongation at break of films. • Chitosan-based GFSE composite films inhibited the proliferation of fungal growth. - Abstract: Chitosan-based composite films with different amounts of grapefruit seed extract (GFSE) (0.5, 1.0 and 1.5% v/v) were fabricated via solution casting technique. Experimental results showed that GFSE was uniformly dispersed within all chitosan film matrices. The presence of GFSE made the films more amorphous and tensile strength decreased, while elongation at break values increased as GFSE content increased. Results from the measurement of light transmission revealed that increasing amounts of GFSE (from 0.5 to 1.5% v/v) did not affect transparency of the films. Furthermore, packaging of bread samples with chitosan-based GFSE composite films inhibited the proliferation of fungal growth as compared to control samples. Hence, chitosan-based GFSE composite films have the potential to be a useful material in the area of food technology.

  5. Antimicrobial activity of nisin incorporated in pectin and polylactic acid composite films against Listeria monocytogenes

    Science.gov (United States)

    Extruded composite films from 20% pectin and 80% polylactic acids (PLA) were developed and nisin was loaded into films by a diffusion post extrusion. Inhibitory activities of the films against Listeria monocytogenes were evaluated in brain heart infusion (BHI) broth, liquid egg white and orange juic...

  6. Polymer−metal organic framework composite films as affinity layer for capacitive sensor devices

    NARCIS (Netherlands)

    Sachdeva, S.; Gravesteijn, Dirk J; Soccol, D.; Kapteijn, F.; Sudhölter, E.J.R.; Gascon, J.; Smet, de L.C.P.M.

    2016-01-01

    We report a simple method for sensor development using polymer-MOF composite films. Nanoparticles of NH2-MIL-53(Al) dispersed in a Matrimid polyimide were applied as a thin film on top of capacitive sensor devices with planar electrodes. These drop-cast films act as an affinity layer. Sensing

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-06-15

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

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

    Science.gov (United States)

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

    2016-06-01

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

  9. On the Crystal Structural Control of Sputtered TiO2 Thin Films.

    Science.gov (United States)

    Jia, Junjun; Yamamoto, Haruka; Okajima, Toshihiro; Shigesato, Yuzo

    2016-12-01

    In this study, we focused on the origin on the selective deposition of rutile and anatase TiO2 thin films during the sputtering process. The observation on microstructural evolution of the TiO2 films by transmission electron microscopy revealed the coexistence of rutile and anatase TiO2 phases in the initial stage under the preferential growth conditions for the anatase TiO2; the observations further revealed that the anatase phase gradually dominated the crystal structure with increasing film thickness. These results suggest that the bombardment during the sputtering deposition did not obviously affect the TiO2 crystal structure, and this was also confirmed by off-axis magnetron sputtering experiments. We also investigated the mechanism of the effect of Sn impurity doping on the crystal structure using first-principles calculations. It is found that the formation energy of Sn-doped rutile TiO2 is lower than that of Sn-doped anatase TiO2; this suggests that the Sn-doped TiO2 favours the rutile phase. These results offer a guideline for the utilization of selective deposition of rutile and anatase TiO2 thin films in various industrial applications.

  10. Characterization of rhenium oxide films and their application to liquid crystal cells

    Science.gov (United States)

    Cazzanelli, E.; Castriota, M.; Marino, S.; Scaramuzza, N.; Purans, J.; Kuzmin, A.; Kalendarev, R.; Mariotto, G.; Das, G.

    2009-06-01

    Rhenium trioxide exhibits high electronic conductivity, while its open cubic crystal structure allows an appreciable hydrogen intercalation, generating disordered solid phases, with protonic conductivity. Rhenium oxide thin films have been obtained by thermal evaporation of ReO3 powders on different substrates, maintained at different temperatures, and also by reactive magnetron sputtering of a Re metallic target. A comparative investigation has been carried out on these films, by using micro-Raman spectroscopy and x-ray diffraction. Two basic types of solid phases appear to grow in the films: a red metallic HxReO3 compound, with distorted perovskite structures, like in the bulk material, and ordered HReO4 crystals based on tetrahedral perrhenate ions. Because of its conduction properties, the electrical and electro-optical behaviors of ReO3 films deposited on standard indium tin oxide/glass substrate have been tested inside asymmetric nematic liquid crystal cells, showing an appreciable capability of rectification of their electro-optical response, in similar way to tungsten trioxide.

  11. On the Crystal Structural Control of Sputtered TiO2 Thin Films

    Science.gov (United States)

    Jia, Junjun; Yamamoto, Haruka; Okajima, Toshihiro; Shigesato, Yuzo

    2016-07-01

    In this study, we focused on the origin on the selective deposition of rutile and anatase TiO2 thin films during the sputtering process. The observation on microstructural evolution of the TiO2 films by transmission electron microscopy revealed the coexistence of rutile and anatase TiO2 phases in the initial stage under the preferential growth conditions for the anatase TiO2; the observations further revealed that the anatase phase gradually dominated the crystal structure with increasing film thickness. These results suggest that the bombardment during the sputtering deposition did not obviously affect the TiO2 crystal structure, and this was also confirmed by off-axis magnetron sputtering experiments. We also investigated the mechanism of the effect of Sn impurity doping on the crystal structure using first-principles calculations. It is found that the formation energy of Sn-doped rutile TiO2 is lower than that of Sn-doped anatase TiO2; this suggests that the Sn-doped TiO2 favours the rutile phase. These results offer a guideline for the utilization of selective deposition of rutile and anatase TiO2 thin films in various industrial applications.

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

    Science.gov (United States)

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

    2008-01-01

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

  13. Composition, XRD and morphology study of laser prepared LiNbO3 films

    Science.gov (United States)

    Jelínek, M.; Havránek, V.; Remsa, J.; Kocourek, T.; Vincze, A.; Bruncko, J.; Studnička, V.; Rubešová, K.

    2013-03-01

    LiNbO3 films were deposited by PLD from LiNbO3 crystalline or from three different stoichiometric or Li-enriched LiNbO3 targets. Polycrystalline films were prepared on SiO2/Si or sapphire substrates at temperatures T S ˜650-750 °C. Main attention was paid to the influence of targets preparation and the deposition conditions on films composition, morphology and crystallinity. The thin-film morphology was determined by SEM microscopy. The composition was measured by SIMS, RBS, PIXE and PIGE methods. Highly oriented, smooth and stoichiometric LiNbO3 films were synthesized.

  14. Optical properties of zirconium oxynitride films: The effect of composition, electronic and crystalline structures

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, P. [Centro de Física, Universidade do Minho, 4710-057 Braga (Portugal); Borges, J., E-mail: joelborges@fisica.uminho.pt [Centro de Física, Universidade do Minho, 4710-057 Braga (Portugal); Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, Prague 6 (Czech Republic); Rodrigues, M.S. [Centro de Física, Universidade do Minho, 4710-057 Braga (Portugal); Barradas, N.P. [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10 (km 139,7), 2695-066 Bobadela LRS (Portugal); Alves, E. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Espinós, J.P.; González-Elipe, A.R. [Instituto de Ciencia de Materiales de Sevilla (CSIC-University Sevilla), Avda. Américo Vespucio 49, 41092 Sevilla (Spain); Cunha, L.; Marques, L.; Vasilevskiy, M.I.; Vaz, F. [Centro de Física, Universidade do Minho, 4710-057 Braga (Portugal)

    2015-12-15

    Highlights: • Optical behaviour of ZrO{sub x}N{sub y} films were correlated with structural properties. • A continuous depopulation of the d-band and an opening of an energy gap was observed. • Drude–Lorentz parameters changed for the metallic samples. • Optical bandgap of the films increases with non-metallic elements incorporation. - Abstract: This work is devoted to the investigation of zirconium oxynitride (ZrO{sub x}N{sub y}) films with varied optical responses prompted by the variations in their compositional and structural properties. The films were prepared by dc reactive magnetron sputtering of Zr, using Ar and a reactive gas mixture of N{sub 2} + O{sub 2} (17:3). The colour of the films changed from metallic-like, very bright yellow-pale and golden yellow, for low gas flows to red-brownish for intermediate gas flows. Associated to this colour change there was a significant decrease of brightness. With further increase of the reactive gas flow, the colour of the samples changed from red-brownish to dark blue or even to interference colourations. The variations in composition disclosed the existence of four different zones, which were found to be closely related with the variations in the crystalline structure. XRD analysis revealed the change from a B1 NaCl face-centred cubic zirconium nitride-type phase for films prepared with low reactive gas flows, towards a poorly crystallized over-stoichiometric nitride phase, which may be similar to that of Zr{sub 3}N{sub 4} with some probable oxygen inclusions within nitrogen positions, for films prepared with intermediate reactive gas flows. For high reactive gas flows, the films developed an oxynitride-type phase, similar to that of γ-Zr{sub 2}ON{sub 2} with some oxygen atoms occupying some of the nitrogen positions, evolving to a ZrO{sub 2} monoclinic type structure within the zone where films were prepared with relatively high reactive gas flows. The analysis carried out by reflected electron energy

  15. Characterization of bamboo cellulose-based green composite film by NMMO technology

    Institute of Scientific and Technical Information of China (English)

    Hongxia FANG; Jinyu SUN; Lei ZHANG

    2008-01-01

    Bamboo cellulose, lignin and starch have been molecularly blended to form homogeneous composite films by NMMO-technology. The structural properties of the films were investigated with FTIR, WAXD and AFM technologies, respectively. The results show that bamboo cellulose, lignin and starch have been molecularly blended through NMMO-technology. There was a two-phase system consisting of ternary composite components as one phase and pores as the other on the surface of the composite film. Because of the existence of homogeneous phase structure formed by the rearrangement of the nat-ural polymer molecules, the film shows good properties originating from the mutual supplement of different nat-ural components.

  16. Non-isothermal crystallization kinetics in melt-drawn PCL/PLA microfibrillar composites

    Science.gov (United States)

    Kratochvíl, Jaroslav; Kelnar, Ivan

    2016-05-01

    The non-isothermal crystallization kinetics of the system poly(ɛ-caprolactone)/poly(lactic acid)/clay C15 and related microfibrillar composites has been studied using a simple method based on mathematical treatment of the DSC cumulative crystallization curves in their inflection point. The method provides three kinetic parameters: temperature of start of crystallization, temperature of maximum crystallization rate, and numerical value of the maximum crystallization rate. In the range of cooling rates 5 - 20°C/min, the temperatures of crystallization start and of maximum crystallization rate are determined with standard deviation of 0.3 and 0.4°C, respectively. Average standard deviation of maximum crystallization rate is 1.0 K-1 corresponding to coefficient of variation 5.8 %. Repeatability is slightly better at lower cooling rates. The modified samples show intensive nucleation effect during the non-isothermal crystallization, as demonstrated by their values of temperatures of crystallization start and of maximum crystallization rate that are significantly higher than that of neat PCL. The highest maximum crystallization rate has been found for the blend PCL/PLA 80/20. The proposed method does not refer to any crystallization model and does not require exact determination of the starting point of crystallization. On the other hand, it does not provide any information about dimensionality of crystal growth. The method is particularly useful for characterizing a series of samples derived by modification of the neat polymer.

  17. Enhanced piezoelectric performance of composite sol-gel thick films evaluated using piezoresponse force microscopy.

    Science.gov (United States)

    Liu, Yuanming; Lam, Kwok Ho; Kirk Shung, K; Li, Jiangyu; Zhou, Qifa

    2013-05-14

    Conventional composite sol-gel method has been modified to enhance the piezoelectric performance of ceramic thick films. Lead zirconate titanate (PZT) and lead magnesium niobate-lead titanate (PMN-PT) thick films were fabricated using the modified sol-gel method for ultrasonic transducer applications. In this work, piezoresponse force microscopy was employed to evaluate the piezoelectric characteristics of PZT and PMN-PT composite sol-gel thick films. The images of the piezoelectric response and the strain-electric field hysteresis loop behavior were measured. The effective piezoelectric coefficient (d33,eff) of the films was determined from the measured loop data. It was found that the effective local piezoelectric coefficient of both PZT and PMN-PT composite films is comparable to that of their bulk ceramics. The promising results suggest that the modified composite sol-gel method is a promising way to prepare the high-quality, crack-free ceramic thick films.

  18. Facile Preparation and Characterization of Poly (3-hexylthiophene)/Multiwalled Carbon Nanotube Thermoelectric Composite Films

    Science.gov (United States)

    Du, Y.; Shen, S. Z.; Yang, W. D.; Chen, S.; Qin, Z.; Cai, K. F.; Casey, P. S.

    2012-06-01

    This paper reports a novel, cost-effective, scalable, and simple method for preparing poly(3-hexylthiophene)/multiwalled carbon nanotube (P3HT/MWCNT) nanocomposite films. The P3HT/MWCNT films were prepared by oxidative polymerization of 3-hexylthiophene in chloroform solution containing dispersed MWCNT. The phase composition and microstructure of the composite films were analyzed by x-ray diffraction (XRD), Fourier-transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, and field-emission scanning electron microscopy. The composite films were smooth, dense, and uniform. The thermoelectric properties of the composite films were measured at room temperature. The electrical conductivity and Seebeck coefficient of the films with MWCNT content of 5 wt.% were ~1.3 × 10-3 S/cm and 131.0 μV/K, respectively.

  19. Garnet composite films with Au particles fabricated by repetitive formation for enhancement of Faraday effect

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, H; Nakai, Y [Department of Electronics and Intelligent Systems, Tohoku Institute of Technology, 35-1 Yagiyama-Kasumi, Taihaku, Sendai, Miyagi 982-8577 (Japan); Mizutani, Y; Inoue, M [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Tempaku, Toyohashi, Aichi 441-8580 (Japan); Fedyanin, A A, E-mail: uchida_hn@tohtech.ac.jp [Faculty of Physics, Moscow State University, Moscow 119992 (Russian Federation)

    2011-02-16

    To prepare garnet (Bi : YIG) composite films with Au particles, we used a repetitive formation method to increase the number density of particles. On increasing the number of repetitions, the diameter distribution of the particles changed. After five repetitions using 5 nm Au films, the diameter distribution separated into two size groups. Shift of wavelength-excited localized surface plasmon resonance is discussed relative to the diameter distribution. In the composite films, enhancement of Faraday rotation associated with surface plasmons was observed. With six repetitions, a maximum enhanced rotation of -1.2{sup 0} was obtained, which is 20 times larger than that of a single Bi : YIG film. The figures of merit for the composite films are discussed. The thickness of a Bi : YIG composite film working for enhanced Faraday rotation was examined using an ion milling method.

  20. Two-dimensional colloidal crystal assisted formation of conductive porous gold films with flexible structural controllability.

    Science.gov (United States)

    Lu, Zhicheng; Liu, Chen; Han, Heyou

    2015-01-01

    Two-dimensional (2D) colloidal crystals of polystyrene (PS) particles were used as a structure-controlling template to fabricate conductive Au films with an ordered array of nanoholes. The fabrication mainly involved the functionalization of the supporting substrate with polyelectrolyte (PE) functional layers, self-assembly of Au nanoparticles, and electroless deposition of gold. The self-assembly of Au nanoparticles and electroless deposition of gold were macroscopically monitored using ultraviolet-visible (UV-vis) spectroscopy based on the changes in both the extinction spectra of Au nanoparticles and the optical responses of ordered arrays of PS particles. By scanning electron microscopy (SEM) characterization, it was found that Au nanoparticles were assembled into a film structure with orderly dispersed nanoholes and the deposition of gold was confined to the preformed Au nanoparticle films. During the formation of Au films, PE layer structure, Au nanoparticle size and heating treatment applied to the PS template could influence the structures of conductive porous Au films such as the hole diameter, film thickness, and hole diameter/wall thickness ratio (D/W). In addition, this paper also described electrochemical cyclic voltammetry (CV) employed to demonstrate the porosity of the ultimate Au films.

  1. Preparation and characterization of Co epitaxial thin films on Al{sub 2}O{sub 3}(0001) single-crystal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki, E-mail: yabuhara@futamoto.elect.chuo-u.ac.jp [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan)

    2011-01-01

    Co epitaxial thin films were prepared on Al{sub 2}O{sub 3}(0001) single-crystal substrates in a substrate temperature range between 50 and 500 deg. C by ultra high vacuum molecular beam epitaxy. Effects of substrate temperature on the structure and the magnetic properties of the films were investigated. The films grown at temperatures lower than 150 deg. C consist of fcc- Co(111) crystal. With increasing the substrate temperature, hcp-Co(0001) crystal coexists with the fcc crystal and the volume ratio of hcp to fcc crystal increases. The films prepared at temperatures higher than 250 deg. C consist primarily of hcp crystal. The film growth seems to follow island-growth mode. The films consisting primarily of hcp crystal show perpendicular magnetic anisotropy. The domain structure and the magnetization properties are influenced by the magnetocrystalline anisotropy and the shape anisotropy caused by the film surface roughness.

  2. Electrochemical synthesis of poly(pyrrole-co-o-anisidine)/chitosan composite films

    Science.gov (United States)

    Yalçınkaya, Süleyman; Çakmak, Didem

    2017-05-01

    In this study, poly(pyrrole-co-o-anisidine)/chitosan composite films were electrochemically synthesized in various monomers feed ratio (pyrrole: o-anisidine; 9:1, 7:3, 1:1, 3:7 and 1:9) of pyrrole and o-anisidine on the platinum electrode. Electrochemical synthesis of the composite films was carried out via cyclic voltammetry technique. They were characterized by FT-IR, cyclic voltammetry, SEM micrographs, digital images, TGA and DSC techniques. The SEM results indicated that the particle size of the composite decreased with increasing o-anisidine ratio and the films became more likely to be smooth morphology. The TGA results proved that the film of the composite with 1:1 ratio showed highest final degradation temperature and lowest weight loss (83%) compared to copolymer and 9:1 1:9 composite films. The 1:1 composite film had higher thermal stability than copolymer and the other composite films (9:1 1:9). Meanwhile, electrochemical studies exhibited that the 1/9 composite film had good electrochemical stability as well.

  3. Preparation and properties of biodegradable films from Sterculia urens short fiber/celluose green composites

    CSIR Research Space (South Africa)

    Jayaramudu, J

    2013-04-01

    Full Text Available of the composites films is discussed. This paper presents the developments made in the area of biodegradable S. urens short fiber/cellulose (SUSF/cellulose) composite films, buried in the soil and later investigated by the (POM), before and after biodegradation has...

  4. Influence of high loading of cellulose nanocrystals in polyacrylonitrile composite films

    Science.gov (United States)

    Jeffrey Luo; Huibin Chang; Amir A. Bakhtiary Davijani; H. Clive Liu; Po-Hsiang Wang; Robert J. Moon; Satish Kumar

    2017-01-01

    Polyacrylonitrile-co-methacrylic acid (PAN-co-MAA) and cellulose nanocrystal (CNC) composite films were produced with up to 40 wt% CNC loading through the solution casting method. The rheological properties of the solution/suspensions and the structural, optical, thermal, and mechanical properties of the resulting films were investigated. The viscosity of the composite...

  5. Anisotropic conductance of the multiwall carbon nanotube array/silicone elastomer composite film

    Energy Technology Data Exchange (ETDEWEB)

    Yao Yuan; Liu Changhong; Fan Shoushan [Tsinghua-Foxconn Nanotechnology Research Center and Department of Physics, Tsinghua University, Beijing 100084 (China)

    2006-09-14

    Multiwall carbon nanotube array/silicone elastomer composite films have been fabricated with an in situ injection modelling method. The transverse conductivity of the composite films is larger than the lateral conductivity because the aligned carbon nanotube array is embedded into the polymer matrix. The nonlinear I-V curve has been analysed and the temperature-dependent transport behaviour has been investigated.

  6. Synthesis and Photocatalytic Property of ZnO/TiO2 Inverse Opals Films with Controllable Composition and Topology

    Science.gov (United States)

    Xu, Jiao; Yang, Bei-fang; Fu, Zheng-ping; Wen, Mei-wang; Zhao, Yong-xun

    2012-04-01

    A novel method to fabricate composition- and topology-controlled ZnO/TiO2 inverse opals (IO) films using a positive sacrificial ZnO IO template has been developed. This method includes a two-step process, preparation of ZnO IO by a simple electrochemical deposition using a self-assembly polystyrene colloidal crystal template and preparation of ZnO/TiO2 IO by a liquid phase deposition (LPD) process at room temperature. The composition and topology of ZnO/TiO2 IO can be easily controlled by changing the duration of the LPD. After 20 min LPD process, a ZnO/TiO2 composite IO with non-close-packed face-centered cubic air sphere array was obtained. Prolonging the duration to 60 min, a pure TiO2 IO (TIO-LPD60) with obviously thickened walls was formed. The formation mechanism for the compositional and topological variation was discussed. A preliminary study on UV photocatalytic property of the samples for degradation of methylene blue reveals that the composition and topology significantly influenced the photocatalytic activity of the IO film. The ZnO/TiO2 composite IO demonstrates a higher degree of activity than both pure ZnO and pure TiO2 IO, although they have a similar IO wall thickness. Moreover, with increasing IO wall thickness from ~52 nm to ~90 nm, TIO-LPD60 exhibits the highest level of photocatalytic performance.

  7. Memory effect in composites of liquid crystal and silica aerosil

    Energy Technology Data Exchange (ETDEWEB)

    Relaix, Sabrina; Leheny, Robert L.; Reven, Linda; Sutton, Mark (McGill); (JHU)

    2012-02-07

    Aerosil silica nanoparticles dispersed in a liquid crystal (LC) possess the interesting property of keeping memory of an electric- or magnetic-field-induced orientation. Two types of memory have been identified: thermally erasable memory arising from the pinning of defect lines versus a 'permanent' memory where the orientation persists even after thermal cycling the samples up to the isotropic phase. To address the source of the latter type of memory, solid-state nuclear magnetic resonance spectroscopy and conventional x-ray diffraction (XRD) were first combined to characterize the LC orientational order as a function of multiple in-field temperature cycles. Microbeam XRD was then performed on aligned gels of different concentrations to gain knowledge of the structural properties at the origin of the memory effect. No detectable anisotropy of the gel or significant breaking of silica strands with heating ruled out the formation of an anisotropic silica network as the source of the permanent memory as previously proposed. Instead, support for a role of the surface memory effect, well known for planar substrates, in stabilizing the permanent memory was deduced from 'training' of the composites, that is, optimizing the orientational order through the thermal in-field cycling. The ability to train the composites is inversely proportional to the strength of the random-field disorder. The portion of thermally erasable memory also decreases as the silica density increases. We propose that the permanent memory originates from the surface memory effect operating at points of intersection in the silica network. These areas, where the LC is strongly confined with conflicted surface interactions, are trained to achieve an optimized orientation and subsequently act as sites from which the LC orientational order regrows after zero-field thermal cycling up to the isotropic phase.

  8. Studies of Second Order Optical Nonlinearities of 4-Aminobenzophenone (ABP) Single Crystal Films

    Science.gov (United States)

    Bhowmik, Achintya; Thakur, Mrinal

    1998-03-01

    Specific organic materials exhibit very high second order optical susceptibilities. Growth of single crystal films of these materials and characterization of nonlinear optical properties are necessary for implementation of device applications. We have grown large-area films ( 1 cm^2 area, 4 μm thick) of ABP by a modification of the shear method. Single crystal nature of the films was confirmed by polarized optical microscopy. X-ray diffraction analysis showed a [100] surface orientation. The absorption spectra revealed transparency from 390 nm to 1940 nm. Significant elements of the second order optical susceptibility tensor were measured by detailed SHG experiments using a Nd:YAG laser (1064 nm, 100 ps, 82 MHz). Second-harmonic power was measured using lock-in detection with carefully selected polarization conditions while the film was rotated about the propagation direction. Using LiNbØas the reference, d-coefficients of ABP were found to be d_23=7.2 pm/V and d_22=0.7 pm/V. Type-I and type-II phase-matching directions were identified on the film by analyzing the optical indicatrix surfaces at fundamental and second-harmonic frequencies.

  9. Pyrolysis mechanism for recycle renewable resource from polarizing film of waste liquid crystal display panels.

    Science.gov (United States)

    Wang, Ruixue; Xu, Zhenming

    2014-08-15

    Liquid crystal display (LCD) panels mainly consist of polarizing film, liquid crystal and glass substrates. In this study, a novel pyrolysis model and a pyrolysis mechanism to recover the reusable resource from polarizing film of waste LCD panels was proposed. Polarizing film and its major components, such as cellulose triacetate (TAC) and polyvinyl alcohol (PVA) were pyrolyzed, respectively, to model the pyrolysis process. The pyrolysis process mainly generated a large ratio of oil, a few gases and a little residue. Acetic acid was the main oil product and could be easily recycled. The pyrolysis mechanism could be summarized as follows: (i) TAC, the main component of polarizing film, was heated and generated active TAC with a low polymerization, and then decomposed into triacetyl-d-glucose. (ii) Some triacetyl-d-glucose generated triacetyl-d-mannosan and its isomers through an intramolecular dehydration, while most triacetyl-d-glucose generated the main oil product, namely acetic acid, through a six-member cyclic transition state. (iii) Meanwhile, other products formed through a series of bond cleavage, dehydration, dehydrogenation, interesterification and Diels-Alder cycloaddition. This study could contribute significantly to understanding the polarizing film pyrolysis performance and serve as guidance for the future technological parameters control of the pyrolysis process.

  10. Mechanical and microstructural properties of "wet" alginate and composite films containing various carbohydrates.

    Science.gov (United States)

    Harper, B Allison; Barbut, Shai; Smith, Alexandra; Marcone, Massimo F

    2015-01-01

    Composite "wet" alginate films were manufactured from alginate-carbohydrate solutions containing 5% alginate and 0.25% pectin, carrageenan (kappa or iota), potato starch (modified or unmodified), gellan gum, or cellulose (extracted or commercial). The "wet" alginate films were used as a model to understand co-extruded alginate sausage casings that are currently being used by several sausage manufacturers. The mechanical, optical, and microstructural properties of the calcium cross-linked composite films were explored. In addition, the water holding capacity and textural profile analysis properties of the alginate-carbohydrate gels were studied. The results indicate that the mechanical properties of "wet" alginate films/casings can be modified by adding various carbohydrates to them. Alginate films with pectin, carrageenan, and modified potato starch had significantly (P alginate films. The alginate-pectin films also had greater (P alginate films. Alginate films with extracted cellulose, commercial cellulose, and modified potato starch had lower (P alginate control films. Transmission electron microscopy images showed a very uniform alginate network in the control films. Several large cellulose fibers were visible in the films with extracted cellulose, while the cellulose fibers in the films with commercial cellulose were difficult to distinguish. Despite these apparent differences in cellulose fiber length, the 2 cellulose films had similar puncture and tensile properties.

  11. Aluminum induced crystallization of strongly (111) oriented polycrystalline silicon thin film and nucleation analysis

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A polycrystalline silicon thin film was fabricated on glass substrate by means of aluminum induced crystallization (AIC). Al and α-Si layers were deposited by magnetron sputtering respectively and annealed at 480°C for 1 h to realize layer exchange. The polycrystalline silicon thin film was continuous and strongly (111) oriented. By analyzing the structure variation of the oxidation membrane and lattice mismatch between γ-Al2O3 and Si, it was concluded that aluminum promoted the formation of (111) oriented silicon nucleus by controlling the orientation of γ-Al2O3, which was formed at the early stage of annealing.

  12. Thin film of sol-gel deposited in photonic crystal fiber for cholesterol detection

    Science.gov (United States)

    Razo-Medina, D. A.; Alvarado-Méndez, E.; Trejo-Durán, M.

    2015-04-01

    In this work, the fabrication of thin films mixed with cholesterol enzyme as recognition component is shown, using solgel technique. The film was deposited at one end of photonic crystal fiber (optrode), which was used as carrier medium of sol-gel matrix. The concentration of cholesterol in the test sample was determined by the use of transmittance. Measuring device consists of a power source (laser diode), optrode and a light detector. The laser beam is transmitted through the optrode; the variations of intensity depending on cholesterol concentration are emitted to be detected by a photoresistor.

  13. Tunable Bloch surface waves in anisotropic photonic crystals based on lithium niobate thin films.

    Science.gov (United States)

    Kovalevich, Tatiana; Ndao, Abdoulaye; Suarez, Miguel; Tumenas, Saulius; Balevicius, Zigmas; Ramanavicius, Arunas; Baleviciute, Ieva; Häyrinen, Markus; Roussey, Matthieu; Kuittinen, Markku; Grosjean, Thierry; Bernal, Maria-Pilar

    2016-12-01

    We present an original type of one-dimensional photonic crystal that includes one anisotropic layer made of a lithium niobate thin film. We demonstrate the versatility of such a device sustaining different Bloch surface waves (BSWs), depending on the orientation of the incident wave. By varying the orientation of the illumination of the multilayer, we measured an angle variation of 7° between the BSWs corresponding to the extraordinary and the ordinary index of the lithium niobate thin film. The potential of such a platform opens the way to novel tunable and active planar optics based on the electro- and thermo-optical properties of lithium niobate.

  14. Molecular beam epitaxy growth and optical properties of single crystal Zn3N2 films

    Science.gov (United States)

    Wu, Peng; Tiedje, T.; Alimohammadi, H.; Bahrami-Yekta, V.; Masnadi-Shirazi, M.; Wang, Cong

    2016-10-01

    Single crystal Zn3N2 films with (100) orientation have been grown by plasma-assisted molecular beam epitaxy on MgO and A-plane sapphire substrates with in situ optical reflectance monitoring of the growth. The optical bandgap was found to be 1.25-1.28 eV and an electron Hall mobility as high as 395 cm2 V-1 s-1 was measured. The films were n-type with carrier concentrations in the 1018-1019 cm-3 range.

  15. Nanoscale investigations on interchain organization in thin films of polymer-liquid crystal blend

    Science.gov (United States)

    Villeneuve-Faure, C.; Le Borgne, D.; Ventalon, V.; Seguy, I.; Moineau-Chane Ching, K. I.; Bedel-Pereira, E.

    2017-07-01

    Optimized nanomorphology in organic thin active layers is crucial for good performance in organic solar cells. However, the relation between morphology and electronic properties at nanoscale remains not completely understood. Here, we study the effect of film thickness and temperature annealing on the ordering of poly(3-hexylthiophene) chains when the polymer is blended with a columnar liquid crystalline molecule. Electronic absorption, atomic force microscopy measurements, and Raman spectroscopy show that morphology and chain ordering of the blend depend on the film thickness. We highlight the benefit of using a liquid crystal in organic blends, opening the way to use simple processing methods for the fabrication of organic electronic devices.

  16. Electro-optical properties of polymer stabilized cholesteric liquid crystal film

    Institute of Scientific and Technical Information of China (English)

    Ma Ji; Zheng Zhi-Gang; Liu Yong-Gang; Xuan Li

    2011-01-01

    Liquid crystals (LCs) and polymers are extensively used in various electro-optical applications. In this paper, normal mode polymer stabilized cholesteric LC film is prepared and studied. The effects of chiral dopant and monomer concentrations on the electro-optical properties, such as contrast ratio, driving voltage, hysteresis width and response time, are investigated. The reasons of electro-optical properties influenced by the concentrations of the materials are discussed. Through the proper material recipe, the electro-optical properties of polymer stabilized cholesteric LC film can be optimized.

  17. Fresnel analysis of Kretschmann geometry with a uniaxial crystal layer on a three-layered film

    Directory of Open Access Journals (Sweden)

    Yu-Ju Hung

    2016-04-01

    Full Text Available The use of total internal reflection within the prism coupling scheme is a simple approach to the generation of surface plasmon polariton waves on a metal/dielectric interface. Unfortunately, an anisotropic layer on a metallic film complicates the derivation of resonance angle. In this study, we present clear Fresnel analysis of a liquid crystal film on a metal surface. Few current simulation packages enable the analysis of multiple layers with a single anisotropic layer. The proposed formulation process is applicable to multi-layered structures.

  18. Single crystal PMN-PT/epoxy 1-3 composite for energy-harvesting application.

    Science.gov (United States)

    Ren, Kailiang; Liu, Yiming; Geng, Xuecang; Hofmann, Heath F; Zhang, Qiming M

    2006-03-01

    One key parameter in using electroactive materials to harvest electric energy from mechanical sources is the energy conversion efficiency. Recently, it was shown that, in the relaxor ferroelectric PMN-PT single crystals, a very high longitudinal electromechanical coupling factor (>90%) can be obtained. This paper investigates energy harvesting using 1-3 composites of PMN-PT single crystals in a soft epoxy matrix. It is shown that 1-3 composites enable the single crystals operating in the longitudinal mode to achieve high efficiency for energy harvesting, and the soft-polymer, matrix-supported single-crystal rods maintain high mechanical integrity under different external loads. For comparison, 1-3 composites with piezoceramic PZT also are investigated in energy-harvesting applications, and the results show that the high coupling factor of single crystal PMN-PT 1-3 composites leads to much higher electric energy output for similar mechanical energy input. The harvested energy density of 1-3 composite with single crystal (22.1 mW/cm3 under a stress of 40.4 MPa) is about twice of that harvested with PZT ceramic 1-3 composite (12 mW/cm3 under a stress of 39 MPa). At a higher stress level, the harvested-energy density of 1-3 PMN-PT single crystal composite can reach 96 mW/cm3.

  19. An asymmetric electrically conducting self-aligned graphene/polymer composite thin film for efficient electromagnetic interference shielding

    Directory of Open Access Journals (Sweden)

    Pradip Kumar

    2017-01-01

    Full Text Available Here, we study the self-aligned asymmetric electrically conductive composite thin film prepared via casting of graphene oxide (GO/poly (vinylidene-hexafluoropropylene (PVDF-HFP dispersion, followed by low temperature hydriodic acid reduction. The results showed that composite thin film revealed the high orientation of graphene sheets along the direction of film surface. However, graphene sheets are asymmetrically distributed along the film thickness direction in the composite film. Both sides of as prepared composite film showed different surface characteristics. The asymmetric surface properties of composite film induced distinction of surface resistivity response; top surface resistivity (21 Ohm is ∼ 4 times higher than bottom surface resistivity (5 Ohm. This asymmetric highly electrically conducting composite film revealed efficient electromagnetic interference (EMI shielding effectiveness of ∼ 30 dB. This study could be crucial for achieving aligned asymmetric composite thin film for high-performance EMI shielding radiation.

  20. STUDY ON COMPOSITION, MICROSTRUCTURE AND HARDNESS OF DLC FILMS BY VCAD

    Institute of Scientific and Technical Information of China (English)

    L. Chen; Z.Y. Liu; D.C. Zeng; W.Q. Qiu; Z.H. Yuan; S.S. Lin; H.J. Hou

    2003-01-01

    DLC super-hard films have been deposited on the substrates of single crystalline Si, pure Ti and stainless steel 18-8 by a method of vacuum cathode arc deposition(VCAD). The composition, microstructure and micro-hardness of the films have been studied in this paper. The results indicate that hardness of the DLC films is different on the different substrates. Hardness of the films increases with decreasing in surface roughness of the films. The maximum value of micro-hardness belongs to the DLC films deposited under the hydrogen pressure of 0.35Pa and the negative bias of 100V.

  1. Transparent Conductive Films Fabricated from Polythiophene Nanofibers Composited with Conventional Polymers

    Directory of Open Access Journals (Sweden)

    Borjigin Aronggaowa

    2013-11-01

    Full Text Available Transparent, conductive films were prepared by compositing poly(3-hexylthiophene (P3HT nanofibers with poly(methyl methacrylate (PMMA. The transparency, conductivity, atmospheric stability, and mechanical strength of the resulting nanofiber composite films when doped with AuCl3 were evaluated and compared with those of P3HT nanofiber mats. The conductivity of the nanofiber composite films was 4.1 S∙cm−1, which is about seven times less than that which was previously reported for a nanofiber mat with the same optical transmittance (~80% reported by Aronggaowa et al. The time dependence of the transmittance, however, showed that the doping state of the nanofiber composite films in air was more stable than that of the nanofiber mats. The fracture stress of the nanofiber composite film was determined to be 12.3 MPa at 3.8% strain.

  2. Superhydrophobicity and regeneration of PVDF/SiO2 composite films

    Science.gov (United States)

    Liu, Tao; Li, Xianfeng; Wang, Daohui; Huang, Qinglin; Liu, Zhen; Li, Nana; Xiao, Changfa

    2017-02-01

    Superhydrophobicity of polymers is easily destroyed by careless touching due to the softness of microstructures. In this study, based on a well-constructed polyvinylidene fluoride (PVDF) surface, a novel superhydrophobic PVDF/SiO2 composite film was fabricated by adding hydrophobic SiO2 nanoparticle and solvent into a coagulation bath. The water contact angle of the composite film reached 162.3° and the sliding angle was as low as 1.5°. More importantly, the composite film could be regenerated only through immersing the composite film in the designed regeneration agent. The composition of the designed regeneration agent ensured that SiO2 nanoparticles were firmly adhered on the film surface even under the ultrasonic cleaning. Hence, the superhydrophobicity and self-cleaing property could be regenerated and maintained effectively, and moreover, these propeties could resist a proper pressure. In addition, after many rubbing-regenerating cycles, the regeneration method was still valid.

  3. Formation of magnetically anisotropic composite films at low magnetic fields

    Science.gov (United States)

    Ghazi Zahedi, Maryam; Ennen, Inga; Marchi, Sophie; Barthel, Markus J.; Hütten, Andreas; Athanassiou, Athanassia; Fragouli, Despina

    2017-04-01

    We present a straightforward two-step technique for the fabrication of poly (methyl methacrylate) composites with embedded aligned magnetic chains. First, ferromagnetic microwires are realized in a poly (methyl methacrylate) solution by assembling iron nanoparticles in a methyl methacrylate solution under heat in an external magnetic field of 160 mT. The simultaneous thermal polymerization of the monomer throughout the wires is responsible for their permanent linkage and stability. Next, the polymer solution containing the randomly dispersed microwires is casted on a solid substrate in the presence of a low magnetic field (20–40 mT) which induces the final alignment of the microwires into long magnetic chains upon evaporation of the solvent. We prove that the presence of the nanoparticles assembled in the form of microwires is a key factor for the formation of the anisotropic films under low magnetic fields. In fact, such low fields are not capable of driving and assembling dispersed magnetic nanoparticles in the same type of polymer solutions. Hence, this innovative approach can be utilized for the synthesis of magnetically anisotropic nanocomposite films at low magnetic fields.

  4. Finite element simulations of thin-film composite BAW resonators.

    Science.gov (United States)

    Makkonen, T; Holappa, A; Ellä, J; Salomaa, M M

    2001-09-01

    A finite element method (FEM) formulation is presented for the numerical solution of the electroelastic equations that govern the linear forced vibrations of piezoelectric media. A harmonic time dependence is assumed. Both of the approaches, that of solving the field problem (harmonic analysis) and that of solving the corresponding eigenvalue problem (modal analysis), are described. A FEM software package has been created from scratch. Important aspects central to the efficient implementation of FEM are explained, such as memory management and solving the generalized piezoelectric eigenvalue problem. Algorithms for reducing the required computer memory through optimization of the matrix profile, as well as Lanczos algorithm for the solution of the eigenvalue problem are linked into the software from external numerical libraries. Our FEM software is applied to detailed numerical modeling of thin-film bulk acoustic wave (BAW) composite resonators. Comparison of results from 2D and full 39 simulations of a resonator are presented. In particular, 3D simulations are used to investigate the effect of the top electrode shape on the resonator electrical response. The validity of the modeling technique is demonstrated by comparing the simulated and measured displacement profiles at several frequencies. The results show that useful information on the performance of the thin-film resonators can be obtained even with relatively coarse meshes and, consequently, moderate computational resources.

  5. Ferroelectric properties of dysprosium-doped Bi4Ti3O12 thin films crystallized in various atmospheres

    Institute of Scientific and Technical Information of China (English)

    CHENG Chuan-pin; TANG Ming-hua; YE Zhi; ZHOU Yic-hun; ZHENG Xue-jun; ZHONG Xiang-li; HU Zeng-shun

    2006-01-01

    Dysprosium-doped Bi4Ti3O12 (Bi3.4Dy0.6Ti3O12,BDT) ferroelectric thin films were deposited on Pt(111)/Ti/SiO2/Si(111) substrates by chemical solution deposition (CSD) and crystallized in nitrogen,air and oxygen atmospheres,respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the crystal structure,the surface and cross-section morphology of the deposited ferroelectric films. The results show that the crystallization atmosphere has significant effect on determining the crystallization and ferroelectric properties of the BDT films. The film crystallized in nitrogen at a relatively low temperature of 650 ℃,exhibits excellent crystallinity and ferroelectricity with a remanent polarization of 2Pr = 24.9 μC/cm2 and a coercive field of 144.5 kV/cm. While the films annealed in air and oxygen at 650 ℃ do not show good crystallinity and ferroelectricity until they are annealed at 700 ℃. The structure evolution and ferroelectric properties of BDT thin films annealed under different temperatures (600-750 ℃) were also investigated. The crystallinity of the BDT films is improved and the average grain size increases when the annealing temperature increases from 600 ℃ to 750 ℃ at an interval of 50 ℃. However,the polarization of the films is not monotonous function of the annealing temperature.

  6. Preparation and Photoemission Spectra of Rb3C60 Single-Crystal Thin Films

    Institute of Scientific and Technical Information of China (English)

    李宏年; 吴太权; 陈晓; 李海洋; 鲍世宁; 徐亚伯; 钱海杰; 易卜拉欣奎热西; 刘风琴

    2002-01-01

    Rb3 C60 single-crystal thin films were prepared on the cleaved (111) surface of C60 single crystal. The photoemission spectrum line shapes of the lowest unoccupied molecular orbital (LUMO) derived band at room temperature and 150K were established by synchrotron radiation photoemission spectrum measurements. The density of states near the Fermi level was distinctly affected by temperature. No less than six sub-peaks of the LUMOband were observed even at room temperature. The existence of so many sub-peaks offered the opportunities to analyse in more detail the orientational structure and the electron-Boson interactions of the narrow-band metallic Rb3 C60 .

  7. Tunable absorption in heterostructures composed of a highly absorptive metallic film and Fibonacci fractal photonic crystals

    Science.gov (United States)

    Qiao, Wei; Sun, Jie; Du, Gui-Qiang

    2016-03-01

    We have theoretically investigated the anomalous optical properties of heterostructures composed of a highly absorptive metal film and a truncated Fibonacci fractal photonic crystal. It is found that one or multiple highly reflected peaks, even enhanced transmission narrowband, can be realized in the near-complete absorption broadband, where the photonic crystals are selected with various Fibonacci sequences or a given sequence as the basic unit. These properties are significant to design important reflection or transmission optical devices in the visible and near-infrared ranges.

  8. Equilibrium Water Contents of Cellulose Films Determined via Solvent Exchange and Quartz Crystal Microbalance with Dissipation Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Kittle, Joshua D; Du, Xiaosong; Jiang, Feng; Qian, Chen; Heinze, Thomas; Roman, Maren; Esker, Alan R

    2011-08-08

    Model cellulose surfaces have attracted increasing attention for studying interactions with cell wall matrix polymers and as substrates for enzymatic degradation studies. Quartz crystal microbalance with dissipation monitoring (QCM-D) solvent exchange studies showed that the water content of regenerated cellulose (RC) films was proportional to the film thickness (d) and was consistent with about five water molecules per anhydroglucose unit. Sulfated nanocrystalline cellulose (SNC) and desulfated nanocrystalline cellulose (DNC) films had comparable water contents and contained about five times more water than RC films. A cellulase mixture served as a probe for studies of substrate accessibility and degradation. Cellulase adsorption onto RC films was independent of d, whereas degradation times increased with d. However, adsorption onto SNC and DNC films increased with d, whereas cellulase degradation times for DNC films were independent of studied d. Enhanced access to guest molecules for SNC and DNC films revealed they are more porous than RC films.

  9. Equilibrium water contents of cellulose films determined via solvent exchange and quartz crystal microbalance with dissipation monitoring.

    Science.gov (United States)

    Kittle, Joshua D; Du, Xiaosong; Jiang, Feng; Qian, Chen; Heinze, Thomas; Roman, Maren; Esker, Alan R

    2011-08-08

    Model cellulose surfaces have attracted increasing attention for studying interactions with cell wall matrix polymers and as substrates for enzymatic degradation studies. Quartz crystal microbalance with dissipation monitoring (QCM-D) solvent exchange studies showed that the water content of regenerated cellulose (RC) films was proportional to the film thickness (d) and was consistent with about five water molecules per anhydroglucose unit. Sulfated nanocrystalline cellulose (SNC) and desulfated nanocrystalline cellulose (DNC) films had comparable water contents and contained about five times more water than RC films. A cellulase mixture served as a probe for studies of substrate accessibility and degradation. Cellulase adsorption onto RC films was independent of d, whereas degradation times increased with d. However, adsorption onto SNC and DNC films increased with d, whereas cellulase degradation times for DNC films were independent of studied d. Enhanced access to guest molecules for SNC and DNC films revealed they are more porous than RC films.

  10. Thin metal film-polymer composite for efficient optoacoustic generation (Conference Presentation)

    Science.gov (United States)

    Lee, Taehwa; Guo, L. Jay

    2016-03-01

    Photoacoustic (PA) conversion of metal film absorbers is known to be inefficient because of their low thermal expansion and high light reflectance, as compared to polymeric materials containing light absorbing fillers. Specifically, the PA signal for metal films is typically an order of magnitude lower than those for PDMS-based composites consisting of carbon materials such as carbon blacks, carbon nanotubes, and carbon fibers. However, the carbon-PDMS composites have several disadvantages, e.g., difficulty in controlling film thickness, aggregation of the carbon fillers, and poor patternablility. To overcome these issues and achieve comparable PA amplitudes, a polymer-metal film composite was developed consisting of a thin metal absorber and adjacent transparent polymer layers. The proposed structure shows efficient PA conversion. The measured PA amplitude of the metal film composite is an order of magnitude higher than that of metal-only samples, and comparable to those of the carbon-PDMS composites. The enhanced PA conversion is accomplished by using metal film of a few tens of nanometers, which greatly facilitates heat transfer from the metal film to the surrounding polymers. Moreover, integrating the metal film composite with a photonic cavity can compensate light absorption loss of the thinner metal film. Theoretical and experimental analysis is conducted for understanding the mechanism behind such improvement. This strategy could be implemented for spatial PA signal patterns, especially for deep tissue PA imaging of implants or image-guiding tools. Furthermore, this approach also provides a guideline for designing photoacoustic transmitters and contrast agents.

  11. Photocatalytic degradation of methyl orange over ITO/Cds/ZnO interface composite films.

    Science.gov (United States)

    Wei, Shouqiang; Shao, Zhongcai; Lu, Xudong; Liu, Ying; Cao, Linlin; He, Yan

    2009-01-01

    ITO/CdS/ZnO interface composite films were successfully prepared by subsequent electrodeposition of CdS and ZnO onto indium tin oxide (ITO) glass substrates. The obtained ITO/CdS/ZnO composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The photocatalytic activity of ITO/CdS/ZnO composite films were investigated using methyl orange (MO) as a model organic compound under UV light irradiation. The influence of operating parameters on MO degradation including initial concentration of MO, pH value of solution, and inorganic anion species over the composite films were examined. A blue shift of absorption threshold was observed for the ITO/CdS/ZnO film in comparison with ITO/ZnO film. ITO/CdS/ZnO composite films prepared under specific conditions showed a higher photocatalytic activity than that of ITO/ZnO films. It was also found that the photocatalytic degradation of MO on the composite films followed pseudo-first order kinetics.

  12. Electrochemical preparation and electrochemical behavior of polypyrrole/carbon nanotube composite films

    Institute of Scientific and Technical Information of China (English)

    Xue-tong ZHANG; Wen-hui SONG

    2009-01-01

    Polypyirole/multiwalled carbon nanotube (MWNT) composite fihns were electrochemically depos-ited in the presence of an ionic surfactant, sodium dodecyl sulfate (SDS), acting as both supporting electrolyte and dispersant. The effects of the surfactant and the MWNT concentrations on the structure at the resulting composite films were investigated. The electrochemical behavior of the resulting polypyrrole/MWNT composite film was investigated aS well bv cyclic voltammogram. The effect of the additional alternating electric field applied during the constant direct potential electrochemical deposition on the morphology and electrochemical behavior of the resulting composite film was also investigated in this study.

  13. Enzymatic degradation processes of lamellar crystals in thin films for poly[(R)-3-hydroxybutyric acid] and its copolymers revealed by real-time atomic force microscopy.

    Science.gov (United States)

    Numata, Keiji; Hirota, Takuya; Kikkawa, Yoshihiro; Tsuge, Takeharu; Iwata, Tadahisa; Abe, Hideki; Doi, Yoshiharu

    2004-01-01

    Enzymatic degradation processes of flat-on lamellar crystals in melt-crystallized thin films of poly[(R)-3-hydroxybutyric acid] (P(3HB)) and its copolymers were characterized by real-time atomic force microscopy (AFM) in a phosphate buffer solution containing PHB depolymerase from Ralstonia pickettii T1. Fiberlike crystals with regular intervals were generated along the crystallographic a axis at the end of lamellar crystals during the enzymatic degradation. The morphologies and sizes of the fiberlike crystals were markedly dependent on the compositions of comonomer units in the polyesters. Length, width, interval, and thickness of the fiberlike crystals after the enzymatic degradation for 2 h were measured by AFM, and the dimensions were related to the solid-state structures of P(3HB) and its copolymers. The width and thickness decreased at the tip of fiberlike crystals, indicating that the enzymatic degradation of crystals takes place not only along the a axis but also along the b and c axes. These results from AFM measurement were compared with the data on crystal size by wide-angle X-ray diffraction, and on lamellar thickness and long period by small-angle X-ray scattering. In addition, the enzymatic erosion rate of flat-on lamellar crystals along the a axis was measured from real-time AFM height images. A schematic glacier model for the enzymatic degradation of flat-on lamellar crystals of P(3HB) by PHB depolymerase has been proposed on the basis of the AFM observations.

  14. Structure and photochromic properties of molybdenumphosphoric acid/TiO2 composite films

    Institute of Scientific and Technical Information of China (English)

    QI He; LIU Yan; FENG Wei; ZHU YiMin

    2009-01-01

    TiO2 sol-gel composite films with dropping molybdenumphosphoric acid (PMoA) have been prepared by sol-gel method. The structure and constitute of composite thin films were studied with Fourier transforms infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and X-ray diffraction (XRD) patterns, respectively. The photochromic behavior and mechanism of composite thin films were inves-tigated with ultraviolet-visible spectra (UV-vis) and electron spin resonance (ESR). FT-IR results showed that the Keggin geometry of PMoA was still preserved inside PMoA/TiO2 composite thin films, and a charge transfer bridge was built at the interface of PMoA and TiO2 through the Mo-O-Ti bond. Surface topography of the composite film showed obvious changes before/after adding PMoA, and the surface topography of composite films showed obvious changes before/after irradiating as well. Composite thin film had reversible photochromic properties. Irradiated with UV light, transparent films changed from colorless to blue and they can bleach completely with ambient air in the dark. ESR re-sults showed that TiO2 were excitated by UV light to produce electrons, which deoxidized PMoA to produce heteropolyblues. The photochromic process of PMoA/TiO2 system was carried through elec-tron transfer mechanism.

  15. Structure and photochromic properties of molybdenumphosphoric acid/TiO2 composite films

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    TiO2 sol-gel composite films with dropping molybdenumphosphoric acid(PMoA) have been prepared by sol-gel method.The structure and constitute of composite thin films were studied with Fourier transforms infrared spectroscopy(FT-IR),atomic force microscopy(AFM),and X-ray diffraction(XRD) patterns,respectively.The photochromic behavior and mechanism of composite thin films were inves-tigated with ultraviolet-visible spectra(UV-vis) and electron spin resonance(ESR).FT-IR results showed that the Keggin geometry of PMoA was still preserved inside PMoA/TiO2 composite thin films,and a charge transfer bridge was built at the interface of PMoA and TiO2 through the Mo-O-Ti bond.Surface topography of the composite film showed obvious changes before/after adding PMoA,and the surface topography of composite films showed obvious changes before/after irradiating as well.Composite thin film had reversible photochromic properties.Irradiated with UV light,transparent films changed from colorless to blue and they can bleach completely with ambient air in the dark.ESR re-sults showed that TiO2 were excitated by UV light to produce electrons,which deoxidized PMoA to produce heteropolyblues.The photochromic process of PMoA/TiO2 system was carried through elec-tron transfer mechanism.

  16. Lifetime analysis of laser crystallized silicon films on glass

    Energy Technology Data Exchange (ETDEWEB)

    Kühnapfel, Sven; Amkreutz, Daniel; Gall, Stefan [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH - Institut Silizium-Photovoltaik, Berlin (Germany); Huang, Jialiang; Teal, Anthony; Kampwerth, Henner; Varlamov, Sergey [University of New South Wales, Sydney (Australia)

    2015-08-07

    Only recently, the quality of liquid phase crystallized silicon directly on glass substrates made a huge leap towards the quality of multi-crystalline wafers with open circuit voltages well above 600 mV. In this paper, we investigate the material quality in order to identify the factors limiting further performance improvements. We employ photoluminescence imaging on a state of the art test structure with lifetime calibration by transient photoluminescence. The resulting lifetime map is converted into an effective diffusion length map and the origin of regions with short lifetimes is investigated with electron backscattering and transmission electron microscopy. High local dislocation densities in areas with dissociated coincidence site lattice boundaries were found to be responsible for the localised quenching of the photoluminescence signal.

  17. Unique Crystal Orientation of Poly(ethylene oxide) Thin Films by Crystallization Using a Thermal Gradient

    DEFF Research Database (Denmark)

    Gbabode, Gabin; Delvaux, Maxime; Schweicher, Guillaume

    2017-01-01

    Poly(ethylene oxide), (PEO), thin films of different thicknesses (220, 450, and 1500 nm) and molecular masses (4000, 8000, and 20000 g/mol) have been fabricated by spin-coating of methanol solutions onto glass substrates. All these samples have been recrystallized from the melt using a directional...

  18. Nanoplate-like tungsten trioxide (hydrate) films prepared by crystal-seed-assisted hydrothermal reaction

    Science.gov (United States)

    Wang, P.; Yang, L.; Dai, B.; Yang, Z.; Guo, S.; Zhu, J.

    2017-07-01

    Vertically-aligned WO3 nanoplates on transparent conducting fluorine-doped tin oxide (FTO) glass were prepared by a facile template-free crystal-seed-assisted hydrothermal method. The effects of the hydrothermal temperature and reaction time on the crystal structure and morphology of the products were investigated by XRD and SEM. The XRD results showed that the as-prepared thin films obtained below 150∘C comprised orthorhombic WO3 ṡ H2O and completely converted to monoclinic WO3 at 180∘C. It was also noted that there was a phase transformation from orthorhombic to monoclinic by increasing the reaction time from 1 to 12 h. SEM analysis revealed that WO3 thin films are composed of plate-like nanostructures.

  19. Bismuth Substituted Yttrium Iron Garnet Single Crystal Films Prepared by Sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Magneto-optic Faraday rotation effect and the amount of bismuth substituted in yttrium iron garnet single crystal films prepared by gel-coating on modified gadolinium-gallium garnet substrates are investigated, where the gel is synthesized by a sol-gel reaction of nitrates and ethylene glycol. The coated gel is annealed in air at temperatures up to 660℃ for 4h, which is about 300℃ lower than that of liquid-phase epitaxy. The maximum amount of Bi substitution is x=2.7 and the crystallization temperature of garnet phase decreases with the increase of x down to 520℃ for x=2.7. In this film, a huge Faraday rotation of -8.1×104 (°)/cm at λ=0.633μm is obtained.

  20. Preparation of room temperature terahertz detector with lithium tantalate crystal and thin film

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun, E-mail: ueoewj@gmail.com; Gou, Jun; Li, Weizhi [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2014-02-15

    Research on room temperature terahertz (THz) detector is essential for promoting the application of THz science and technology. Both lithium tantalate crystal (LiTaO{sub 3}) and lithium tantalate thin film were used to fabricate the THz detector in this paper. Polishing process were used to reduce the thickness of LiTaO{sub 3} crystal slice by chemical mechanical polishing techniques and an improved sol-gel process was used to obtain high concentration LiTaO{sub 3} precursor solution to fabricate LiTaO{sub 3} thin film. Three dimension models of two THz detectors were set up and the temperature increasing map of two devices were simulated using finite element method. The lowest noise equivalent power value for terahertz detector using pyroelectric material reaches 6.8 × 10{sup −9} W at 30 Hz operating frequency, which is suitable for THz imaging application.

  1. Preparation of room temperature terahertz detector with lithium tantalate crystal and thin film

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2014-02-01

    Full Text Available Research on room temperature terahertz (THz detector is essential for promoting the application of THz science and technology. Both lithium tantalate crystal (LiTaO3 and lithium tantalate thin film were used to fabricate the THz detector in this paper. Polishing process were used to reduce the thickness of LiTaO3 crystal slice by chemical mechanical polishing techniques and an improved sol-gel process was used to obtain high concentration LiTaO3 precursor solution to fabricate LiTaO3 thin film. Three dimension models of two THz detectors were set up and the temperature increasing map of two devices were simulated using finite element method. The lowest noise equivalent power value for terahertz detector using pyroelectric material reaches 6.8 × 10−9 W at 30 Hz operating frequency, which is suitable for THz imaging application.

  2. Vapor-crystal phase transition in synthesis of paracetamol films by vacuum evaporation and condensation

    Science.gov (United States)

    Belyaev, A. P.; Rubets, V. P.; Antipov, V. V.; Bordei, N. S.; Zarembo, V. I.

    2014-03-01

    We report on the structural and technological investigations of the vapor-crystal phase transition during synthesis of paracetamol films of the monoclinic system by vacuum evaporation and condensation in the temperature range 220-320 K. The complex nature of the transformation accompanied by the formation of a gel-like phase is revealed. The results are interpreted using a model according to which the vapor-crystal phase transition is not a simple first-order phase transition, but is a nonlinear superposition of two phase transitions: a first-order transition with a change in density and a second-order phase transition with a change in ordering. Micrographs of the surface of the films are obtained at different phases of formation.

  3. Studies on Crystal Orientation of ZnO Film on Sapphire Using High-throughout X-ray Diffraction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The orientation of the nano-columnar ZnO films grown on sapphire using the technique of metal-organic chemical vapor deposition (MOCVD) exhibits deviation because of the mismatch between the crystal lattices of the films and the sapphire substrate. A high-throughout X-ray diffraction method was employed to determine the crystal orientation of the ZnO films at a time scale of the order of minutes based on the general area detection diffraction system (GADDS). This rapid, effective, and ready method, adapted for characterizing the orientation of the nano-columnar crystals is used to directly explain the results of observation of the X-ray diffraction images, by the measurements of the orientations of the crystal columns of the ZnO films along c-axis and in parallel to ab plane.

  4. Random lasing in dye-doped polymer dispersed liquid crystal film

    Science.gov (United States)

    Wu, Rina; Shi, Rui-xin; Wu, Xiaojiao; Wu, Jie; Dai, Qin

    2016-09-01

    A dye-doped polymer-dispersed liquid crystal film was designed and fabricated, and random lasing action was studied. A mixture of laser dye, nematic liquid crystal, chiral dopant, and PVA was used to prepare the dye-doped polymer-dispersed liquid crystal film by means of microcapsules. Scanning electron microscopy analysis showed that most liquid crystal droplets in the polymer matrix ranged from 30 μm to 40 μm, the size of the liquid crystal droplets was small. Under frequency doubled 532 nm Nd:YAG laser-pumped optical excitation, a plurality of discrete and sharp random laser radiation peaks could be measured in the range of 575-590 nm. The line-width of the lasing peak was 0.2 nm and the threshold of the random lasing was 9 mJ. Under heating, the emission peaks of random lasing disappeared. By detecting the emission light spot energy distribution, the mechanism of radiation was found to be random lasing. The random lasing radiation mechanism was then analyzed and discussed. Experimental results indicated that the size of the liquid crystal droplets is the decisive factor that influences the lasing mechanism. The surface anchor role can be ignored when the size of the liquid crystal droplets in the polymer matrix is small, which is beneficial to form multiple scattering. The transmission path of photons is similar to that in a ring cavity, providing feedback to obtain random lasing output. Project supported by the National Natural Science Foundation of China (Grant No. 61378042), the Colleges and Universities in Liaoning Province Outstanding Young Scholars Growth Plans, China (Grant No. LJQ2015093), and Shenyang Ligong University Laser and Optical Information of Liaoning Province Key Laboratory Open Funds, China.

  5. Effect of cross linking of PVA/starch and reinforcement of modified barley husk on the properties of composite films.

    Science.gov (United States)

    Mittal, Aanchal; Garg, Sangeeta; Kohli, Deepak; Maiti, Mithu; Jana, Asim Kumar; Bajpai, Shailendra

    2016-10-20

    Barley husk (BH) was graft copolymerized by palmitic acid. The crystalline behavior of BH decreased after grafting. Poly vinyl alcohol (PVA)/starch (St) blend film, urea formaldehyde cross linked PVA/St films and composite films containing natural BH, grafted BH were prepared separately. The effect of urea/starch ratio, content of BH and grafted BH on the mechanical properties, water uptake (%), and biodegradability of the composite films was observed. With increase in urea: starch ratio from 0 to 0.5 in the blend, tensile strength of cross linked film increased by 40.23% compared to the PVA/St film. However, in grafted BH composite film, the tensile strength increased by 72.4% than PVA/St film. The degradation rate of natural BH composite film was faster than PVA/St film. Various films were characterized by SEM, FT-IR and thermal analysis.

  6. Pyroelectric composite film for X-ray intensity detection

    Directory of Open Access Journals (Sweden)

    Walter Katsumi Sakamoto

    2012-04-01

    Full Text Available Composite material obtained with modified lead titanate (Pz34 ferroelectric ceramic and polyether-ether-ketone (PEEK polymer matrix was used as sensitive component to measure X-ray intensity in a novel detection system. The sensing element works as a thermal transducer, converting a non-quantified thermal flux into an output measurable quantity of electrical voltage. The samples were obtained up to 60 vol.% of ceramic, by hot pressing the mixture of Pz34 and PEEK powders at 368 °C and applying 12 MPa pressure for 2.0 hours. The sensor response varies from 2.70 to 0.80 V in the energy fluence rate range of 6.30 to 37.20 W.m-2. The absorbed incident energy was analyzed as a function of the ionizing energy. Furthermore, by measuring the pyroelectric activity of the composite film it was observed that there is no degradation of the sensor after the irradiation.

  7. A Semitransparent and Flexible Single Crystal Si Thin Film: Silicon on Nothing (SON) Revisited.

    Science.gov (United States)

    Park, Sanghyun; Lee, Yong Hwan; Wi, Jung-Sub; Oh, Jihun

    2016-07-27

    Ultrathin single crystal Si films offer a versatile vehicle for high performance flexible and semitransparent electric devices due to their outstanding optoelectric and mechanical properties. Here, we demonstrate the formation of an ultrathin (100) single crystal Si film based on morphological evolution of nanoporous Si during high temperature annealing. Square arrays of cylindrical Si pores are formed by nanoimprint lithography and deep reactive etching and then subjected to annealing in hydrogen ambient. By controlling the aspect ratio of nanoporous Si, defect-free single crystal Si membranes with controlled thicknesses from 330 to 470 nm are formed on a platelike void after the annealing. In addition, we investigate the role of oxygen impurities in a hydrogen atmosphere on defect formation on a Si surface and eliminate the oxygen-related defects on Si by controlling gas phase diffusion of oxygen impurities during annealing in a conventional tube furnace. Finally, we demonstrate the transfer of a defect-free, flexible, and wafer scale Si membrane with thickness of 470 nm onto a PDMS substrate, utilizing the platelike void under the membrane as a releaser. The ultrathin flexible Si film on PDMS shows optical transmittance of about 30-70% in visible and near-infrared light.

  8. Diode laser crystallization processes of Si thin-film solar cells on glass

    Directory of Open Access Journals (Sweden)

    Yun Jae Sung

    2014-07-01

    Full Text Available The crystallization of Si thin-film on glass using continuous-wave diode laser is performed. The effect of various processing parameters including laser power density and scanning speed is investigated in respect to microstructure and crystallographic orientation. Optimal laser power as per scanning speed is required in order to completely melt the entire Si film. When scan speed of 15–100 cm/min is used, large linear grains are formed along the laser scan direction. Laser scan speed over 100 cm/min forms relatively smaller grains that are titled away from the scan direction. Two diode model fitting of Suns-Voc results have shown that solar cells crystallized with scan speed over 100 cm/min are limited by grain boundary recombination (n = 2. EBSD micrograph shows that the most dominant misorientation angle is 60°. Also, there were regions containing high density of twin boundaries up to ~1.2 × 10-8/cm2. SiOx capping layer is found to be effective for reducing the required laser power density, as well as changing preferred orientation of the film from ⟨ 110 ⟩ to ⟨ 100 ⟩ in surface normal direction. Cracks are always formed during the crystallization process and found to be reducing solar cell performance significantly.

  9. Control of polythiophene film microstructure and charge carrier dynamics through crystallization temperature

    KAUST Repository

    Marsh, Hilary S.

    2014-03-22

    The microstructure of neat conjugated polymers is crucial in determining the ultimate morphology and photovoltaic performance of polymer/fullerene blends, yet until recently, little work has focused on controlling the former. Here, we demonstrate that both the long-range order along the (100)-direction and the lamellar crystal thickness along the (001)-direction in neat poly(3-hexylthiophene) (P3HT) and poly[(3,3″-didecyl[2,2′:5′, 2″-terthiophene]-5,5″-diyl)] (PTTT-10) thin films can be manipulated by varying crystallization temperature. Changes in crystalline domain size impact the yield and dynamics of photogenerated charge carriers. Time-resolved microwave conductivity measurements show that neat polymer films composed of larger crystalline domains have longer photoconductance lifetimes and charge carrier yield decreases with increasing crystallite size for P3HT. Our results suggest that the classical polymer science description of temperature-dependent crystallization of polymers from solution can be used to understand thin-film formation in neat conjugated polymers, and hence, should be considered when discussing the structural evolution of organic bulk heterojunctions. © 2014 Wiley Periodicals, Inc.

  10. Transverse anisotropic magnetoresistance effects in pseudo-single-crystal γ'-Fe4N thin films

    Science.gov (United States)

    Kabara, Kazuki; Tsunoda, Masakiyo; Kokado, Satoshi

    2016-05-01

    Transverse anisotropic magnetoresistance (AMR) effects, for which magnetization is rotated in an orthogonal plane to the current direction, were investigated at various temperatures, in order to clarify the structural transformation from a cubic to a tetragonal symmetry in a pseudo-single-crystal Fe4N film, which is predicted from the usual in-plane AMR measurements by the theory taking into account the spin-orbit interaction and crystal field splitting of 3d bands. According to a phenomenological theory of AMR, which derives only from the crystal symmetry, a cos 2θ component ( C2 tr ) exists in transverse AMR curves for a tetragonal system but does not for a cubic system. In the Fe4N film, the C2 tr shows a positive small value (0.12%) from 300 K to 50 K. However, the C2 t r increases to negative value below 50 K and reaches to -2% at 5 K. The drastic increasing of the C2 tr demonstrates the structural transformation from a cubic to a tetragonal symmetry below 50 K in the Fe4N film. In addition, the out-of-plane and in-plane lattice constants (c and a) were precisely determined with X-ray diffraction at room temperature using the Nelson-Riely function. As a result, the positive small C2 t r above 50 K is attributed to a slightly distorted Fe4N lattice (c/a = 1.002).

  11. The formation of organic (propolis films)/inorganic (layered crystals) interfaces for optoelectronic applications

    Science.gov (United States)

    Drapak, S. I.; Bakhtinov, A. P.; Gavrylyuk, S. V.; Kovalyuk, Z. D.; Lytvyn, O. S.

    2008-10-01

    Propolis (honeybee glue) organic films were prepared from an alcoholic solution on the surfaces of inorganic layered semiconductors (indium, gallium and bismuth selenides). Atomic force microscopy (AFM) and X-ray diffraction (XRD) are used to characterize structural properties of an organic/inorganic interfaces. It is shown that nanodimensional linear defects and nanodimensional cavities of various shapes are formed on the van der Waals (VDW) surfaces of layered crystals as a result of chemical interaction between the components of propolis (flavonoids, aminoacids and phenolic acids) and the VDW surfaces as well as deformation interaction between the VDW surfaces and propolis films during their polymerization. The nanocavities are formed as a result of the rupture of strong covalent bonds in the upper layers of layered crystals and have the shape of hexagons or triangles in the (0001) plane. The shape, lateral size and distribution of nanodimensional defects on the VDW surfaces depends on the type of crystals, the magnitude and distribution of surface stresses. We have obtained self-organized nanofold structures of propolis/InSe interface. It is established that such heterostructures have photosensitivity in the infrared range hνpropolis films at room temperature).

  12. Perovskite single crystals and thin films for optoelectronic devices (Conference Presentation)

    Science.gov (United States)

    Li, Gang; Han, Qifeng; Yang, Yang; Bae, Sang-Hoon; Sun, Pengyu

    2016-09-01

    Hybrid organolead trihalide perovskite (OTP) solar cells have developed as a promising candidate in photovoltaics due to their excellent properties including a direct bandgap, strong absorption coefficient, long carrier lifetime, and high mobility. Most recently, formamidinium (NH2CH=NH2+ or FA) lead iodide (FAPbI3) has attracted significant attention due to several advantages: (1) the larger organic FA cation can replace the MA cation and form a more symmetric crystal structure, (2) the smaller bandgap of FAPbI3 allows for near infrared (NIR) absorption, and (3) FAPbI3 has an elevated decomposition temperature and thus potential to improve stability. Single crystals provide an excellent model system to study the intrinsic electrical and optical properties of these materials due to their high purity, which is particularly important to understand the limits of these materials. In this work, we report the growth of large ( 5 millimeter size) single crystal FAPbI3 using a novel liquid based crystallization method. The single crystal FAPbI3 demonstrated a δ-phase to α-phase transition with a color change from yellow to black when heated to 185°C within approximately two minutes. The crystal structures of the two phases were identified and the PL emission peak of the α-phase FAPbI3 (820 nm) shows clear red-shift compared to the FAPbI3 thin film (805 nm). The FAPbI3 single crystal shows a long carrier lifetime of 484 ns, a high carrier mobility of 4.4 cm2·V-1·s-1, and even more interestingly a conductivity of 1.1 × 10-7(ohm·cm)-1, which is approximately one order of magnitude higher than that of the MAPbI3 single crystal. Finally, high performance photoconductivity type photodetectors were successfully demonstrated using the single crystal FAPbI3.

  13. Synthesis and optical properties of complex nanometal composite films

    Science.gov (United States)

    Sandrock, Marie Louise

    We have successfully prepared gold pair particles of various size, shape, and inter-particle spacing using a template synthesis method involving anodic aluminum oxide films as host templates. Both transmission electron microscopy and polarized linear spectroscopy were used to evaluate the sample quality. The nature of the synthesis is such that the rotational axes of the rod-like structures are oriented normal to the host film surface. This characteristic leads to plasmon resonance spectra with dichroic behavior. In general, we found that both the plasmon resonance maxima and intensity are dependent on the size, shape, orientation, and inter-particle spacing of the pair particle nanostructures. We have successfully prepared more complex pair particle structures, including both rod and rod-sphere pairs. Linear polarization spectroscopy indicates that the plasmon resonance maxima are sensitive to both pair-particle geometry and inter-particle spacing. Possible evidence for interaction between the two members of the rod-sphere structure is seen in the experimental spectra. Quasi-static limit models also only qualitatively describe the polarization spectra of the rod-containing systems. We have succeeded in discerning the processes that cause the second harmonic generation of light (SHG) in nanoparticle composite systems. Second harmonic generation (SHG) studies using an incident wavelength of 780 nm indicate that SHG intensities under s-polarization are low and independent of incidence angle (theta) for composites containing centrosymmetric and non-centrosymmetric gold nanostructures. However, in p-polarization, both composites show an increase in SHG counts with theta, with the non-centrosymmetric structures showing a higher SHG signal than their centrosymmetric counterparts. These results are consistent with local-field enhancements arising from long particle axis dipolar plasmon resonances. Thus, we determined that symmetry does indeed play a large role in small

  14. Photonic-Crystal-Based Thin Film Sensor for Detecting Volatile Organic Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hyung Kwan; Park, Jung Yul [Sogang Univ., Seoul (Korea, Republic of)

    2016-03-15

    Early detection of toxic gases, such as volatile organic compounds (VOCs), is important for safety and environmental protection. However, the conventional detection methods require long-term measurement times and expensive equipment. In this study, we propose a thin-film-type chemical sensor for VOCs, which consists of self assembled monosize nanoparticles for 3-D photonic crystal structures and polydimthylsiloxane (PDMS) film. It is operated without any external power source, is truly portable, and has a fast response time. The structure color of the sensor changes when it is exposed to VOCs, because VOCs induce a swelling of the PDMS. Therefore, using this principle of color change, we can create a thin-film sensor for immediate detection of various types of VOCs. The proposed device evidences that a fast response time of just seconds, along with a clear color change, are successfully observed when the sensor is exposed to gas-phase VOCs.

  15. Investigation of crystallization behavior of CIG-Se bi-layer thin films.

    Science.gov (United States)

    Park, Mi Sun; Sung, Shi-Joon; Kim, Dae-Hwan; Kang, Jin-Kyu

    2012-04-01

    Copper indium gallium diselenide (CIGSe) thin film was fabricated via a thermal treatment of GIG-Se bi-layer thin films. A CIG layer was prepared first, by a chemical solution deposition (CSD) process. The Se layer was deposited separately on the CIG layer by evaporation. The GIG-Se bi-layer then underwent a thermal treatment to cause a reaction between the two layers. In order to investigate the mechanism of CIG-Se bi-layer crystallization, the thermal treatment temperature was varied. The properties of the prepared CIGSe2 thin films were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometry (EDS), and UV-visible spectrophotometry.

  16. Near-field lithography on the azobenzene polymer liquid crystal films

    Institute of Scientific and Technical Information of China (English)

    Douguo Zhang; Jian Liu; Zebo Zhang; Li Cao; Anlian Pan; Pei Wang; Yonghua Lu; Ming Bai; Jun Yang; Lin Tang; Jiangying Zhang; Hai Ming; Qijin Zhang

    2005-01-01

    @@ In this article, we reported near-field research on azobenzene polymer liquid crystal films using scanning near-field optical microscopy (SNOM). Optical writing and subsequently topographic reading of the patterns with subwavelength resolution were carried out in our experiments. Nanometer scale dots and lines were successfully fabricated on the films and the smallest dot diameter is about 120 nm. The width of the line fabricated is about 250 nm. This method is also a choice for nanolithography. The mechanism of the surface deformation on the polymer films was briefly analyzed from the viewpoint of gradient force in the optical near field. The intensity distribution of the electric field near the tip aperture was numerically simulated using finite-difference time-domain (FDTD) method and the numerical simulation results were consistent with the experimental results.

  17. Molecular field theory for nematic liquid crystal film with finite layers

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhi-Dong; Li Jing; Wei Huai-Peng

    2005-01-01

    The nematic liquid crystal film composed of n molecular layers is studied based upon a spatially anisotropic pair potential, which reproduces approximately the elastic free energy density. On condition that the system has perfect nematic order, as in the Lebwohl-Lasher model, the director in the film is isotropic. The effect of the temperature is investigated by means of molecular field theory. Some new results are obtained. Firstly, symmetry breaking takes place when taking account of the temperature, and the state with the director along the normal of the film has the lowest free energy. Secondly, the N-I phase transition temperature increases as an effect of finite sizes instead of decreasing as in the Lebwohl-Lasher model. Thirdly, the nematic order is induced in the layers near the surface in the isotropic phase.

  18. Abnormal Crystallization of Silicon Thin Films Deposited by ICP-CVD

    Institute of Scientific and Technical Information of China (English)

    LI Jun-Shuai; YIN Min; WANG Jin-Xiao; HE De-Yan

    2005-01-01

    @@ Silicon thin films are deposited by inductively coupled plasma chemical vapour deposition (ICP-CVD) at a low temperature of 350℃ using a mixture of SiH4 and H2. The structures of the films are characterized by x-ray diffraction and Raman spectra. Under the optimum experimental conditions, we observe that the crystallinity of Si films becomes more excellent and the preferred orientation changes from (111) to (220) with the decreasing dilution of SiH4 in H2. Such an abnormal crystallization is tentatively interpreted in term of the high density,low electron temperature and spatial confinement of the plasma in the process of ICP-CVD.

  19. Composite single crystal silicon scan mirror substrates Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Single crystal silicon is a desirable mirror substrate for scan mirrors in space telescopes. As diameters of mirrors become larger, existing manufacturing...

  20. Crystal imperfections and Mott parameters of sprayed nanostructure IrO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hassanien, A.S., E-mail: a.s.hassanien@gmail.com [Engineering Mathematics and Physics Department, Faculty of Engineering (Shoubra), Benha University (Egypt); Physics Department, Faculty of Science in Ad-Dawadmi, Shaqra University, 11911 (Saudi Arabia); Akl, Alaa A. [Physics Department, Faculty of Science in Ad-Dawadmi, Shaqra University, 11911 (Saudi Arabia)

    2015-09-15

    Nano-crystalline iridium oxide thin films were obtained by a spray pyrolysis technique onto preheated glass substrates. X-ray diffraction reveals that IrO{sub 2} thin films were polycrystalline in the rutile structure with primitive tetragonal lattice and its preferential orientation were along the 〈110〉 and 〈101〉 directions. X-ray diffraction line profile analysis (XRDLPA) was used to assign microstructure and crystal imperfections of IrO{sub 2} thin films. Some important parameters such as crystallite size, microstrain, average residual stress, number of crystallite/cm{sup 2} and dislocation density were studied. The effects of deposition temperatures and solution concentrations on the microstructural and crystal defects were discussed. All estimated values were found to be dependent upon the growth parameters. Mott parameters, trapping state energy and potential barrier were investigated and studied for a defined thin film sample. This sample was selected because it has the suitable conditions for electrochromic applications.

  1. Oxide perovskite crystals for HTSC film substrates microwave applications

    Science.gov (United States)

    Bhalla, A. S.; Guo, Ruyan

    1995-01-01

    The research focused upon generating new substrate materials for the deposition of superconducting yttrium barium cuprate (YBCO) has yielded several new hosts in complex perovskites, modified perovskites, and other structure families. New substrate candidates such as Sr(Al(1/2)Ta(1/2))O3 and Sr(Al(1/2)Nb(1/2))O3, Ba(Mg(1/3)Ta(2/3))O3 in complex oxide perovskite structure family and their solid solutions with ternary perovskite LaAlO3 and NdGaO3 are reported. Conventional ceramic processing techniques were used to fabricate dense ceramic samples. A laser heated molten zone growth system was utilized for the test-growth of these candidate materials in single crystal fiber form to determine crystallographic structure, melting point, thermal, and dielectric properties as well as to make positive identification of twin free systems. Some of those candidate materials present an excellent combination of properties suitable for microwave HTSC substrate applications.

  2. Local structure, composition, and crystallization mechanism of a model two-phase "composite nanoglass"

    Science.gov (United States)

    Chattopadhyay, Soma; Kelly, S. D.; Shibata, Tomohiro; Balasubramanian, M.; Srinivasan, S. G.; Du, Jincheng; Banerjee, Rajarshi; Ayyub, Pushan

    2016-02-01

    We report a detailed study of the local composition and structure of a model, bi-phasic nanoglass with nominal stoichiometry Cu55Nb45. Three dimensional atom probe data suggest a nanoscale-phase-separated glassy structure having well defined Cu-rich and Nb-rich regions with a characteristic length scale of ≈3 nm. However, extended x-ray absorption fine structure analysis indicates subtle differences in the local environments of Cu and Nb. While the Cu atoms displayed a strong tendency to cluster and negligible structural order beyond the first coordination shell, the Nb atoms had a larger fraction of unlike neighbors (higher chemical order) and a distinctly better-ordered structural environment (higher topological order). This provides the first experimental indication that metallic glass formation may occur due to frustration arising from the competition between chemical ordering and clustering. These observations are complemented by classical as well as ab initio molecular dynamics simulations. Our study indicates that these nanoscale phase-separated glasses are quite distinct from the single phase nanoglasses (studied by Gleiter and others) in the following three respects: (i) they contain at least two structurally and compositionally distinct, nanodispersed, glassy phases, (ii) these phases are separated by comparatively sharp inter-phase boundaries, and (iii) thermally induced crystallization occurs via a complex, multi-step mechanism. Such materials, therefore, appear to constitute a new class of disordered systems that may be called a composite nanoglass.

  3. Local structure, composition, and crystallization mechanism of a model two-phase “composite nanoglass”

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, Soma; Shibata, Tomohiro [CSRRI-IIT, MRCAT, Sector 10, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kelly, S. D. [EXAFS Analysis, Bolingbrook, Illinois 60440 (United States); Balasubramanian, M. [Sector 20 XOR, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Srinivasan, S. G.; Du, Jincheng; Banerjee, Rajarshi [Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76203-5017 (United States); Ayyub, Pushan, E-mail: pushan@tifr.res.in [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005 (India)

    2016-02-14

    We report a detailed study of the local composition and structure of a model, bi-phasic nanoglass with nominal stoichiometry Cu{sub 55}Nb{sub 45}. Three dimensional atom probe data suggest a nanoscale-phase-separated glassy structure having well defined Cu-rich and Nb-rich regions with a characteristic length scale of ≈3 nm. However, extended x-ray absorption fine structure analysis indicates subtle differences in the local environments of Cu and Nb. While the Cu atoms displayed a strong tendency to cluster and negligible structural order beyond the first coordination shell, the Nb atoms had a larger fraction of unlike neighbors (higher chemical order) and a distinctly better-ordered structural environment (higher topological order). This provides the first experimental indication that metallic glass formation may occur due to frustration arising from the competition between chemical ordering and clustering. These observations are complemented by classical as well as ab initio molecular dynamics simulations. Our study indicates that these nanoscale phase-separated glasses are quite distinct from the single phase nanoglasses (studied by Gleiter and others) in the following three respects: (i) they contain at least two structurally and compositionally distinct, nanodispersed, glassy phases, (ii) these phases are separated by comparatively sharp inter-phase boundaries, and (iii) thermally induced crystallization occurs via a complex, multi-step mechanism. Such materials, therefore, appear to constitute a new class of disordered systems that may be called a composite nanoglass.

  4. In situ formation of nanometer-scale TiO2/SiC functional compositional film on carbon fiber

    Institute of Scientific and Technical Information of China (English)

    ZHOU Chunhua; YIN Yansheng; ZHANG Shuxiang; LIU Wei

    2005-01-01

    In the toluene solution of the precursor Polycarbosilane (PCS) containing low- molecular-mass additive Ti(OC4H9)4, TiO2/SiC nanometer-scale functional compositional film with the surface TiO2 layer on CF was formed in situ by means of polymer-derived precursors. The effects of Ti (OC4H9)4 concentrations and the maturating time were studied on the densification and TiO2 particle size of surface layer. The compositions of film were TiO2 and SiC crystal by XRD. According to the results of ESCA analysis, Ti(OC4H9)4 compound oozed gradiently from the pre-ceramic PCS to the surface layer after maturating time of 100 h. In the conditions of 45wt% Ti (OC4H9)4 and 100 h maturation, the nanometer-scale TiO2 particles on continuous surface layer were formed by SEM photographs. The nanometer-scale TiO2/SiC functional compositional film can modify the resistance to oxidation of carbon fiber.

  5. Continuous Preparation of Copper/Carbon Nanotube Composite Films and Application in Solar Cells.

    Science.gov (United States)

    Luo, Xiao Gang; Le Wu, Min; Wang, Xiao Xia; Zhong, Xin Hua; Zhao, Ke; Wang, Jian Nong

    2016-02-08

    Realizing the continuous and large scale preparation of particle/carbon nanotube (CNT) composites with enhanced functionalities, and broad applications in energy conversion, harvesting, and storage systems, remains as a big challenge. Here, we report a scalable strategy to continuously prepare particle/CNT composite films in which particles are confined by CNT films. This is achieved by the continuous condensation and deposition of a cylindrical assembly of CNTs on a paper strip and the in situ incorporation of particles during the layer-by-layer deposition process. A Cu/CNT composite film is prepared as an example; such a film exhibits very high power conversion efficiency when it is used as a counter electrode in a solar cell, compared with previous materials under otherwise identical conditions. The proposed method can be extended to other CNT-based composite films with excellent functionalities for wide applications.

  6. KNN/BNT Composite Lead-Free Films for High-Frequency Ultrasonic Transducer Applications

    Science.gov (United States)

    Lau, Sien Ting; Ji, Hong Fen; Li, Xiang; Ren, Wei; Zhou, Qifa; Shung, K. Kirk

    2011-01-01

    Lead-free K0.5Na0.5NbO3/Bi0.5Na0.5TiO3 (KNN/BNT) films have been fabricated by a composite sol-gel technique. Crystalline KNN fine powder was dispersed in the BNT precursor solution to form a composite slurry which was then spin-coated onto a platinum-buffered Si substrate. Repeated layering and vacuum infiltration were applied to produce 5-μm-thick dense composite film. By optimizing the sintering temperature, the films exhibited good dielectric and ferroelectric properties comparable to PZT films. A 193-MHz high-frequency ultrasonic transducer fabricated from this composite film showed a −6-dB bandwidth of approximately 34%. A tungsten wire phantom was imaged to demonstrate the capability of the transducer. PMID:21244994

  7. Photocatalytic degradation of methyl orange over ITO/CdS/ZnO interface composite films

    Institute of Scientific and Technical Information of China (English)

    WEI Shouqiang; SHAO Zhongcai; LU Xudong; LIU Ying; CAO Linlin; HE Yan

    2009-01-01

    ITO/CdS/ZnO interface composite films were successfully prepared by subsequent electrodeposition of CdS and ZnO onto indium tin oxide (ITO) glass substrates. The obtained ITO/CdS/ZnO composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The photocatalytic activity of ITO/CdS/ZnO composite films were investigated using methyl orange (MO) as a model organic compound under UV light irradiation. The influence of operating parameters on MO degradation including initial concentration of MO, pH value of solution, and inorganic anion species over the composite films were examined. A blue shift of absorption threshold was observed for the ITO/CdS/ZnO film in comparison with ITO/ZnO film. ITO/CdS/ZnO composite films prepared under specific conditions showed a higher photocatalytic activity than that of ITO/ZnO films. It was also found that the photocatalytic degradation of MO on the composite filing followed pseudo-first order kinetics.

  8. PREPARATION,CHARACTERIZATION AND ELECTROCHEMICAL PROPERTIES OF POLYPYRROLE-POLYSTYRENE SULFONIC ACID COMPOSITE FILM

    Institute of Scientific and Technical Information of China (English)

    Liang-ti Qu; Gao-quan Shi; Chen Liu; Jin-ying Yuan; Wen-bin Qian

    2005-01-01

    Polypyrrole-polystyrene sulfonic acid (PPy-PSSA) composite films have been electrosynthesized in an aqueous solution of PSSA. The electro-active films exhibit cation exchange during the redox process. Infrared, Raman and energydispersive spectroscopic results demonstrated that the polyanion of PSS- is co-deposited into the PPy matrix and couldn't be stripped from the film extensively by dedoping. The doping level together with dipolaron content of the PPy-PSSA composite film increases during electrochemical polymerization process. SEM images revealed that the composite film has smooth and compact morphology and AFM pictures suggested that PPy chains are possibly grown perpendicular to the electrode surface. TGA tests indicated that the composite films has much better thermal stability than that of pure PPy.Furthermore, electrochemical studies showed that the relaxation process at certain holding potential has great effect on the shape of the cyclic voltammetric curves of PPy-PSSA composite film. The composite film exhibits cation and anion exchange during the redox process after undergoing the relaxation step. It is more difficult for divalent anion to enter the polymer matrix than a univalent ion, and a large cation such as (CH3CH2CH2CH2)4N+ cannot be involved in the ion exchange process.

  9. Polyhydroxyalkanoate-based thin films : characterization and optimization for calcium phosphate crystallization

    OpenAIRE

    Jagoda, Agnieszka Maria

    2013-01-01

    Novel polymer-inorganic composites attract scientific and commercial attention as potential biomaterials for orthopedic applications, due to the fact that currently used materials have still many drawbacks, e.g. problems with cell attachment or degradation products toxicity. Furthermore, scientific research progressively focuses on mimicking the structure and function of the body’s organs. For example, bone is a natural composite of an organic matrix (collagen) and inorganic crystals (calcium...

  10. Perovskite CH3NH3PbI3 crystals and films. Synthesis and characterization

    Science.gov (United States)

    Semenova, O. I.; Yudanova, E. S.; Yeryukov, N. A.; Zhivodkov, Y. A.; Shamirzaev, T. S.; Maximovskiy, E. A.; Gromilov, S. A.; Troitskaia, I. B.

    2017-03-01

    Synthesis of organometal halide perovskite CH3NH3PbI3 has received much attention recently because of promising photosensitive properties usable for solid state solar cell (SSSC). Here the crystals of tetragonal phase (I4/mcm, a =8.8743 Å, c =12.6708 Å) of CH3NH3PbI3 were prepared. Formation of the CH3NH3PbI3 crystals was controlled by the SEM, EDS, XRD and Raman spectroscopy. Optical characteristics of the crystals were obtained using PL spectrometry and spectral ellipsometry methods. PL spectra of orthorhombic phase of CH3NH3PbI3 crystals were recorded the first time. Taking into account the practice use, the CH3NH3PbI3 films are obtained via the sol-gel method with ;spin-on; coating of CH3NH3PbI3 sol. The films are 500 nm in thickness and exhibit an openwork structure. Such a structure is optimal for SSSC construction because it increases the surface contact area between CH3NH3PbI3 and p-conductor.

  11. Electrical and thermal properties of polycrystalline Si thin films with phononic crystal nanopatterning for thermoelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, Masahiro, E-mail: nomura@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, Tokyo 153–8505 (Japan); Institute for Nano Quantum Information Electronics, The University of Tokyo, Tokyo 153–8505 (Japan); Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg 79110 (Germany); Kage, Yuta [Institute of Industrial Science, The University of Tokyo, Tokyo 153–8505 (Japan); Müller, David; Moser, Dominik; Paul, Oliver [Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg 79110 (Germany)

    2015-06-01

    Electrical and thermal properties of polycrystalline Si thin films with two-dimensional phononic patterning were investigated at room temperature. Electrical and thermal conductivities for the phononic crystal nanostructures with a variety of radii of the circular holes were measured to systematically investigate the impact of the nanopatterning. The concept of phonon-glass and electron-crystal is valid in the investigated electron and phonon transport systems with the neck size of 80 nm. The thermal conductivity is more sensitive than the electrical conductivity to the nanopatterning due to the longer mean free path of the thermal phonons than that of the charge carriers. The values of the figure of merit ZT were 0.065 and 0.035, and the enhancement factors were 2 and 4 for the p-doped and n-doped phononic crystals compared to the unpatterned thin films, respectively, when the characteristic size of the phononic crystal nanostructure is below 100 nm. The greater enhancement factor of ZT for the n-doped sample seems to result from the strong phonon scattering by heavy phosphorus atoms at the grain boundaries.

  12. Surface plasmon sensor with gold film deposited on a two-dimensional colloidal crystal

    Science.gov (United States)

    Li, Yuanyuan; Sun, Jie; Wang, Li; Zhan, Peng; Cao, Zhishen; Wang, Zhenlin

    2008-08-01

    A sensor based on surface plasmon resonance (SPR) of plasmonic crystals fabricated via a colloidal-crystal-assisted templating method is studied. Plasmonic crystals are prepared by depositing a thin gold (Au) layer onto a two-dimensional array of polystyrene spheres self-assembled on a quartz substrate. The enhanced transmission as a result of the SPR of Au plasmonic crystals, which are immersed in different ambient liquids, are measured and compared with that of polystyrene (PS) microsphere templates of different sizes, both before and after removal of Au nanoprisms formed on the quartz substrate through pores among the spheres. It is found that the measured sensitivities exhibit a linear dependence on the refractive index of the surrounding medium and are linked to coupling effects between SPRs on the corrugated Au film and nanoislands. The feasibility of the SPR system in molecular monolayer detection is further demonstrated through a formation of alkanethiolate self-assembled monolayers on the Au film surface, which causes a 4 nm red-shift of the main SPR.

  13. Near-Field Optical Microscopy of Defects in Cholesteric Oligomeric Liquid Crystal Films

    Energy Technology Data Exchange (ETDEWEB)

    Lukishova, S.G.; Schmid, A.W.

    2006-08-18

    This paper describes formation of 2-D hexagonal structures with a periodicity ~0.5-0.8 um in the defects of thin films of cholesteric oligomeric liquid crystals prepared by the evaporation of the solvent from the oligomer solution on the substrate. These regular arrays were observed by scanning near-field optical and concurrent atomic force microscopy. The mechanisms considered are both Benard-Marangoni and buoyancy conventions induced by solvent evaporation and air-bubble creation around the condensed water droplets from the air during evaporative cooling. Hexagonal structures prepared by this method can be used in photonic devices for emission enhancement, for instance, in liquid crystal lasers and single photon sources with oligomeric liquid crystal hosts.

  14. Phase-field simulations of faceted Ge/Si-crystal arrays, merging into a suspended film

    Science.gov (United States)

    Salvalaglio, Marco; Bergamaschini, Roberto; Backofen, Rainer; Voigt, Axel; Montalenti, Francesco; Miglio, Leo

    2017-01-01

    We simulate the morphological evolution of Ge microcrystals, grown out-of-equilibrium on deeply patterned Si substrates, as resulting from surface diffusion driven by the tendency toward the minimization of the surface energy. In particular, we report three-dimensional phase-field simulations accounting for the realistic surface energy anisotropy of Ge/Si crystals. In Salvalaglio et al. (2015) [10] it has been shown both by experiments and simulations that annealing of closely spaced crystals leads to a coalescence process with the formation of a suspended film. However, this was explained only by considering an isotropic surface energy. Here, we extend such a study by showing first the morphological changes of faceted isolated crystals. Then, the evolution of dense arrays is considered, describing their coalescence along with the evolution of facets. Combined with the previous results without anisotropy in the surface energy, this work allows us to confirm and assess the key features of the coalescence process.

  15. Influence of the Composition on the Thermoelectric and Electro-physical Properties of Ge-Sb-Te Thin Films for Phase Change Memory Application

    Directory of Open Access Journals (Sweden)

    P.I. Lazarenko

    2016-10-01

    Full Text Available Influence of the composition variation along the quasi-binary line GeTe-Sb2Te3 on the thermoelectric and electro-physical properties of thin films was investigated. GST amorphous thin films have high Seebeck coefficients, which drops nearly on the order of magnitude after the crystallization. Temperature dependences of the resistivities were studied, and it was determined that crystallization temperature increases with moving along the quasi-binary line GeTe-Sb2Te3 from GeSb4Te7 to GeSb2Te4, and then to Ge2Sb2Te5, while the phase transition temperature range decreases. Current-voltage characteristics of amorphous thin films have three voltage ranges with different dependencies due to the different mechanisms of charge carrier transport.

  16. New insight into non-isothermal crystallization of PVA-graphene composites.

    Science.gov (United States)

    Li, Chengpeng; Vongsvivut, Jitraporn; She, Xiaodong; Li, Yongzhen; She, Fenghua; Kong, Lingxue

    2014-10-28

    The melt crystallization of poly(vinyl alcohol) (PVA) and PVA composites has been a controversial subject due to inconclusive evidence and different opinions for its decomposition during crystallization. Using graphene as a model, the melt crystallization of PVA and PVA-graphene composites occurring during single-cycle and multiple-cycle non-isothermal annealing processes was systematically analyzed using different characterization techniques. The results obtained using single-cycle non-isothermal annealing indicated that the entire crystallization process took place through two main stages. The graphene in the PVA matrix regulates the nucleation and crystal growth manner of the PVA, yet resulting in retardation of the entire crystallization. The FTIR and Raman spectroscopic results particularly demonstrated that the annealing process not only improved the crystallinity but also led to clear decomposition in PVA and PVA-graphene composites, such as the elimination of hydroxyl groups and the production of C=C double bonds. The newly produced C=C double bonds were found to be responsible for the retardation of PVA macromolecule crystallization and the breaking of hydrogen bonds among the hydroxyl groups in the PVA chains. In addition, the morphological observation and multi-cycle non-isothermal crystallization further confirmed the existence of decomposition based on the surface damage as well as decreased crystallization enthalpy and crystallization peak temperature. Therefore, the non-isothermal crystallizations of the pure PVA and the PVA-graphene composites were in fact the combination of non-isothermal crystallization and non-isothermal degradation processes.

  17. Crystallization and melting behavior of multi-walled carbon nanotube-reinforced nylon-6 composites

    NARCIS (Netherlands)

    Phang, In Yee; Ma, Jianhua; Shen, Lu; Liu, Tianxi; Zhang, Wei-De

    2006-01-01

    The crystallization and melting behavior of neat nylon-6 (PA6) and multi-walled carbon nanotubes (MWNTs)/PA6 composites prepared by simple melt-compounding was comparatively studied. Differential scanning calorimetry (DSC) results show two crystallization exotherms (TCC, 1 and TCC, 2) for PA6/MWNTs

  18. Crystallization and melting behavior of multi-walled carbon nanotube-reinforced nylon-6 composites

    NARCIS (Netherlands)

    Phang, In Yee; Ma, Jianhua; Shen, Lu; Liu, Tianxi; Zhang, Wei-De

    2006-01-01

    The crystallization and melting behavior of neat nylon-6 (PA6) and multi-walled carbon nanotubes (MWNTs)/PA6 composites prepared by simple melt-compounding was comparatively studied. Differential scanning calorimetry (DSC) results show two crystallization exotherms (TCC, 1 and TCC, 2) for PA6/MWNTs

  19. Novel THTBN/MWNTs-OH polyurethane conducting composite thin films for applications in detection of volatile organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Feng, E-mail: fengxu@snnu.edu.cn; Guo, Shuang; Luo, Yan-Ling, E-mail: luoyanl@snnu.edu.cn

    2014-05-01

    Novel polyurethane (PU) conducting composite thin films based on tetrahydroxyl-terminated poly(butadiene-co-acrylonitrile) (THTBN) and hydroxyl-functionalized multi-walled carbon nanotubes (MWNTs-OH), were prepared via an in-situ coupling reaction route between hydroxyl groups and isocyanate groups. The chemical and crystal structures were characterized by Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD). The morphologies and the dispersion behavior of THTBN/MWNTs-OH were examined by scanning electron microscope (SEM), transmission electron microscopy (TEM) and UV–Vis measurements. The influence of MWNTs-OH loading amount on conducting properties and response to some volatile organic compounds (VOCs) especially benzene and toluene was investigated. The experimental results indicated that MWNTs-OH was tightly encapsulated by PU moieties and homogeneously dispersed in the PU moieties. The as-prepared THTBN/MWNTs-OH PU conducting thin films exhibited strong and selective response to nonpolar benzene and toluene vapors, and the response depends on the loading of MWNTs-OH and VOC vapor concentrations. The improvement in dispersity and sensing properties were closely correlated with the chemical linkage of MWNTs-OH in the THTBN matrices through bridging molecules HDI. The developed PU conducting thin films had fast response and reversibility, significant reproducibility and long-term stability. Therefore, they had a possibility as a candidate of volatile organic solvent vapor sensors. - Highlights: • Novel THTBN/MWNTs-OH PU films were prepared via in-situ coupling reaction. • The structure, morphology and dispersion behavior were examined. • The films displayed good response, selectivity, reversibility and stability. • The response depended upon the loading of MWNTs-OH and vapor concentrations. • The composite films can be used as sensors to detect benzene and toluene vapors.

  20. Incorporation of tin affects crystallization, morphology, and crystal composition of Sn-Beta

    DEFF Research Database (Denmark)

    Tolborg, Søren; Katerinopoulou, A.; Falcone, D. D.;

    2014-01-01

    The crystallization of Sn-Beta in fl uoride medium is greatly in fl uenced by the amount and type of tin source present in the synthesis gel. By varying the amount of tin in the form of tin( IV ) chloride pentahydrate, the time required for crystallization was studied. It was found that tin...... not only drastically a ff ects the time required for crystallization, but also that the presence of tin changes the morphology of the formed Sn-Beta crystals. For low amounts of tin (Si/Sn ¼ 400) crystallization occurs within four days and the Sn-Beta crystals are capped bipyramidal in shape, whereas...... to the minimum time required for obtaining full crystallinity. At excessive crystallization times, the catalytic activity decreased, presumably due to Ostwald ripening...

  1. Crystallization Kinetics of Amorphous In44Sb20Te36 Phase-Change Optical Recording Films on a Nanosecond Scale

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue-Ru; WUTTIG Mattias

    2004-01-01

    @@ We propose a simple method to investigate the crystallization kinetics of amorphous In44Sb20 Te36 films on a nanosecond scale, based on local reflectivity measurements of the nanosecond laser-induced crystallization using a static tester. The pulse condition in terms of laser power and pulse width required for the onset of crystallization is established. Applying this pulse condition and Kissinger's analysis, an activation energy of 0. 57 eV is estimated for the crystallization. This value deviates substantially from the activation energy determined at lower sample temperatures where crystallization proceeds in a time scale of seconds rather than nanoseconds.

  2. Structure and Growth Control of Organic–Inorganic Halide Perovskites for Optoelectronics: From Polycrystalline Films to Single Crystals

    Science.gov (United States)

    Chen, Yani; He, Minhong; Peng, Jiajun; Sun, Yong

    2016-01-01

    Recently, organic–inorganic halide perovskites have sparked tremendous research interest because of their ground‐breaking photovoltaic performance. The crystallization process and crystal shape of perovskites have striking impacts on their optoelectronic properties. Polycrystalline films and single crystals are two main forms of perovskites. Currently, perovskite thin films have been under intensive investigation while studies of perovskite single crystals are just in their infancy. This review article is concentrated upon the control of perovskite structures and growth, which are intimately correlated for improvements of not only solar cells but also light‐emitting diodes, lasers, and photodetectors. We begin with the survey of the film formation process of perovskites including deposition methods and morphological optimization avenues. Strategies such as the use of additives, thermal annealing, solvent annealing, atmospheric control, and solvent engineering have been successfully employed to yield high‐quality perovskite films. Next, we turn to summarize the shape evolution of perovskites single crystals from three‐dimensional large sized single crystals, two‐dimensional nanoplates, one‐dimensional nanowires, to zero‐dimensional quantum dots. Siginificant functions of perovskites single crystals are highlighted, which benefit fundamental studies of intrinsic photophysics. Then, the growth mechanisms of the previously mentioned perovskite crystals are unveiled. Lastly, perspectives for structure and growth control of perovskites are outlined towards high‐performance (opto)electronic devices.

  3. Structure and Growth Control of Organic-Inorganic Halide Perovskites for Optoelectronics: From Polycrystalline Films to Single Crystals.

    Science.gov (United States)

    Chen, Yani; He, Minhong; Peng, Jiajun; Sun, Yong; Liang, Ziqi

    2016-04-01

    Recently, organic-inorganic halide perovskites have sparked tremendous research interest because of their ground-breaking photovoltaic performance. The crystallization process and crystal shape of perovskites have striking impacts on their optoelectronic properties. Polycrystalline films and single crystals are two main forms of perovskites. Currently, perovskite thin films have been under intensive investigation while studies of perovskite single crystals are just in their infancy. This review article is concentrated upon the control of perovskite structures and growth, which are intimately correlated for improvements of not only solar cells but also light-emitting diodes, lasers, and photodetectors. We begin with the survey of the film formation process of perovskites including deposition methods and morphological optimization avenues. Strategies such as the use of additives, thermal annealing, solvent annealing, atmospheric control, and solvent engineering have been successfully employed to yield high-quality perovskite films. Next, we turn to summarize the shape evolution of perovskites single crystals from three-dimensional large sized single crystals, two-dimensional nanoplates, one-dimensional nanowires, to zero-dimensional quantum dots. Siginificant functions of perovskites single crystals are highlighted, which benefit fundamental studies of intrinsic photophysics. Then, the growth mechanisms of the previously mentioned perovskite crystals are unveiled. Lastly, perspectives for structure and growth control of perovskites are outlined towards high-performance (opto)electronic devices.

  4. Isothermal and non-isothermal crystallization kinetics of PVA + ionic liquid [BDMIM][BF4]-based polymeric films

    Science.gov (United States)

    Saroj, A. L.; Chaurasia, S. K.; Kataria, Shalu; Singh, R. K.

    2016-06-01

    The effect of ionic liquid (IL), 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [BDMIM][BF4], on crystallization behavior of poly(vinyl alcohol) (PVA) has been studied by isothermal and non-isothermal differential scanning calorimetry techniques. The PVA + IL based polymer electrolyte films have been prepared using solution casting technique. To describe the isothermal and non-isothermal crystallization kinetics, several kinetic equations have been employed on PVA + IL based films. There is strong dependence of the peak crystallization temperature (Tc), relative degree of crystallity (Xt), half-time of crystallization (t1/2), crystallization rate constants (Avrami Kt and Tobin AT), and Avrami (n) and Tobin (nT) exponents on the cooling rate and IL loading.

  5. Direct Growth of Graphene-like Films on Single Crystal Quartz Substrates

    Science.gov (United States)

    Samsonau, Siarhei

    Direct growth of graphene-like (GL) films (nano-crystalline graphite films) on single crystal quartz substrates by chemical vapor deposition (CVD) from methane and molecular beam growth (MBG) is reported. The GL films have been characterized by means of Raman spectroscopy, atomic force microscopy and electrical measurements. Raman spectroscopy reveals nanocrystalline structure of the films grown at different conditions. The thinnest CVD grown GL films obtained so far have a thickness of 1.5 nm, a relatively rough surface structure and electrical conductivity in the range of 20 kO/square. Low temperature Hall-effect measurements performed on these films have revealed that the major charge carriers are holes with mobility of 40 cm2/Vs at room temperature. While inferior to graphene in terms of electronic properties, the graphene-like films possess very high chemical sensitivity. Study of MBG grown films revealed formation of a non-conductive carbon layer of low crystallinity on the initial stage of the growth process. In order to study the influence of the quartz substrate on the film formation process we performed ab initio simulation of the MBG process. For this simulation we used an atom-by-atom approach, which, we believe, is a closer approximation to the real molecular beam deposition process reported so far. The simulation showed that the initial formation of the film follows the atomic structure of the substrate. This leads to a high content of sp3 hybridized atoms at the initial stage of growth and explains formation of a non-conductive film. Additionally, we demonstrated how a non-conductive film becomes conductive with the increase of the film thickness. These results agree fairly well with the data obtained by AFM, electrical, and Raman measurements conducted on the films grown by MBG. High chemical sensitivity of GL films has been demonstrated by measuring the change in their conductance during exposure to a NO2-containing atmosphere. Sensitivity of CVD

  6. Influence of O2 Flux on Compositions and Properties of ITO Films Deposited at Room Temperature by Direct-Current Pulse Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    WANG Hua-Lin; DING Wan-Yu; LIU Chao-Qian; CHAI Wei-Ping

    2010-01-01

    @@ Indium tin oxide(ITO)films were deposited on glass substrates at room temperature by dc pulse magnetron sputtering.Varying O2 flux,ITO films with different properties are obtained.Both x-ray diffractometer and x-ray photoelectron spectrometer are used to study the change of crystalline structures and bonding structures of ITO films,respectively.Electrical properties are measured by four-point probe measurements.The results indicate that the chemical structures and compositions of ITO films strongly depend on the O2 flux.With increasing O2flux,ITO films display better crystallization,which could decrease the resistivity of films.On the contrary,ITO films contain less O vacancies with increasing O2 flux,which could worsen the conductive properties of films.Without any heat treatment onto the samples,the resistivity of the ITO film could reach 6.0 × 10-4Ω·cm,with the optimai deposition parameter of 0.2 sccm O2 flux.

  7. Crossover from negative to positive magnetoresistance in superconductor/ferromagnet composites thick films

    Energy Technology Data Exchange (ETDEWEB)

    Paredes, O. [Centro de Materiales, Facultad de Ingenieria, Universidad de Narino, Ciudad Universitaria Torobajo, Pasto (Colombia); Baca, E. [Grupo de Ingenieria de Nuevos Materiales, Departamento de Fisica, Universidad del Valle, A.A. 25360 Cali (Colombia); Fuchs, D. [Karlsruhe Institute of Technology, Institut fuer Festkoerperphysik, P.O. Box 3640, Karlsruhe (Germany); Moran, O., E-mail: omoranc@unal.edu.c [Laboratorio de Materiales Ceramicos y Vitreos, Departamento de Fisica, Universidad Nacional de Colombia, Sede Medellin, A.A. 568 Medellin (Colombia)

    2010-11-15

    Thick films of ((Bi, Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x}){sub 0.95}/(LaSr{sub 0.7}Mn{sub 0.3}O{sub 3}){sub 0.05} [(Bi-2223){sub 0.95}(LSMO){sub 0.05}] composites were fabricated on (0 0 1)-oriented LaAlO{sub 3} substrates by a simple melting-quenching-annealing method and their structural, morphological and magnetoelectrical properties carefully studied. Analysis of the X-ray diffraction patterns suggested a highly oriented growth along the c-axis of LSMO. This preferred orientation, with the crystal c-axis being perpendicular to the plane of the substrate, was considered to be indicative of a textured growth mode. Electrical and magnetic measurements showed the presence of ferromagnetism and superconductivity in the composite at temperatures above room temperature and below T{approx}50 K, respectively. A clear crossover from negative to positive magnetoresistance was observed at {approx}80 K in a magnetic field as strong as 5 T.

  8. Effect of surface modification of cellulose nanocrystal on nonisothermal crystallization of poly(β-hydroxybutyrate) composites.

    Science.gov (United States)

    Chen, Jianxiang; Wu, Defeng; Tam, Kam C; Pan, Keren; Zheng, Zhigong

    2017-02-10

    Ring-opening polymerization of l-lactide from cellulose nanocrystal (CNC) surface yielded polylactide-grafted CNC (CNC-g-PLA). The structure and chemical composition of the CNC-g-PLA were characterized by FT-IR, (1)H NMR, XPS and XRD. The crystallization behavior and lamellar structure of poly(β-hydroxybutyrate) (PHB) in the presence of pristine CNC and CNC-g-PLA were elucidated via DSC and SAXS, and Babinet's reciprocity theory was applied. Crystallization kinetics were further analyzed using Ozawa, Mo and Kissinger models. In the presence of pristine CNC, nucleation of PHB crystals led to an increase in the crystallization temperature (Tc) of PHB; while CNC-g-PLA acted as antinucleation agent, resulting in a remarkable reduction in Tc of PHB. Accordingly, the composite with pristine CNC possessed a higher crystallization rate than neat PHB, while CNC-g-PLA displayed the lowest crystallization rate. However, the lamellar structure of PHB was not affected by the presence of pristine and modified CNCs, and almost identical crystallization activation energies as the neat PHB were observed, indicating that nucleation is dominant during PHB crystallization, instead of crystal growth. This study offers a promising approach of using pristine and modified CNCs to control the crystallization of biodegradable aliphatic polyesters. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Preparation of Composite Films of a Conjugated Polymer and C60NWs and Their Photovoltaic Application

    OpenAIRE

    Takatsugu Wakahara; Kun’ichi Miyazawa; Osamu Ito; Nobutaka Tanigaki

    2016-01-01

    Composite films of conjugated polymers, such as poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and poly(3-hexylthiophene) (P3HT), with C60 nanowhiskers (C60NWs) were prepared. The photoluminescence originating from the conjugated MDMO-PPV polymers was effectively quenched in the composite film, indicating a strong interaction between the conjugated polymer and C60NWs. The photovoltaic devices were fabricated using C60NW (conjugated polymer) composite films, result...

  10. Preparation of Composite Films of a Conjugated Polymer and C60NWs and Their Photovoltaic Application

    OpenAIRE

    Takatsugu Wakahara; Kun’ichi Miyazawa; Osamu Ito; Nobutaka Tanigaki

    2016-01-01

    Composite films of conjugated polymers, such as poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and poly(3-hexylthiophene) (P3HT), with C60 nanowhiskers (C60NWs) were prepared. The photoluminescence originating from the conjugated MDMO-PPV polymers was effectively quenched in the composite film, indicating a strong interaction between the conjugated polymer and C60NWs. The photovoltaic devices were fabricated using C60NW (conjugated polymer) composite films, result...

  11. Potentiality of the composite fulleren based carbon films as the stripper foils for tandem accelerators

    CERN Document Server

    Vasin, A V; Rusavsky, A V; Totsky, Y I; Vishnevski, I N

    2001-01-01

    The problem of the radiation resistance of the carbon stripper foils is considered. The short review of the experimental data available in literature and original experimental results of the are presented. In the paper discussed is the possibility of composite fulleren based carbon films to be used for preparation of the stripper foils. Some technological methods for preparation of composite fulleren based carbon films are proposed. Raman scattering and atom force microscopy were used for investigation of the fulleren and composite films deposited by evaporation of the C sub 6 sub 0 fulleren powder.

  12. One-step synthesis of PbSe-ZnSe composite thin film

    OpenAIRE

    2011-01-01

    Abstract This study investigates the preparation of PbSe-ZnSe composite thin films by simultaneous hot-wall deposition (HWD) from multiple resources. The XRD result reveals that the solubility limit of Pb in ZnSe is quite narrow, less than 1 mol%, with obvious phase-separation in the composite thin films. A nanoscale elemental mapping of the film containing 5 mol% PbSe indicates that isolated PbSe nanocrystals are dispersed in the ZnSe matrix. The optical absorption edge of the composite thin...

  13. AFM Study on Interface of HTHP As-grown Diamond Single Crystal and Metallic Film

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The study for the interface of as-grown diamond and metallic film surrounding diamond is an attractive way for understanding diamond growth mechanism at high temperature and high pressure (HTHP), because it is that through the interface carbon atom groups from the molten film are transported to growing diamond surface. It is of great interest to perform atomic force microscopy (AFM) experiment, which provides a unique technique different from that of normal optical and electron microscopy studies, to observe the interface morphology. In the present paper,we report first that the morphologies obtained by AFM on the film are similar to those of corresponding diamond surface, and they are the remaining traces after the carbon groups moving from the film to growing diamond. The fine particles and a terrace structure with homogeneous average step height are respectively found on the diamond (100) and (111) surface. Diamond growth conditions show that its growth rates and the temperature gradients in the boundary layer of the molten film at HTHP result in the differences of surface morphologies on diamond planes,being rough on (100) plane and even on the (111) plane. The diamond growth on the (100) surface at HPHT could be considered as a process of unification of these diamond fine particles or of carbon atom groups recombination on the growing diamond crystal surface. Successive growth layer steps directly suggest the layer growth mechanism of the diamond (111) plane. The sources of the layer steps might be two-dimensional nuclei and dislocations.

  14. Wrinkling of a thin film on a nematic liquid-crystal elastomer

    Science.gov (United States)

    Soni, Harsh; Pelcovits, Robert A.; Powers, Thomas R.

    2016-07-01

    Wrinkles commonly develop in a thin film deposited on a soft elastomer substrate when the film is subject to compression. Motivated by recent experiments [Agrawal et al., Soft Matter 8, 7138 (2012)], 10.1039/c2sm25734c that show how wrinkle morphology can be controlled by using a nematic elastomer substrate, we develop the theory of small-amplitude wrinkles of an isotropic film atop a nematic elastomer. The directors of the nematic elastomer are initially uniform. For uniaxial compression of the film along the direction perpendicular to the elastomer directors, the system behaves as a compressed film on an isotropic substrate. When the uniaxial compression is along the direction of nematic order, we find that the soft elasticity characteristic of liquid-crystal elastomers leads to a critical stress for wrinkling which is very small compared to the case of an isotropic substrate. We also determine the wavelength of the wrinkles at the critical stress and show how the critical stress and wavelength depend on substrate depth and the anisotropy of the polymer chains in the nematic elastomer.

  15. Crystal structure and electrochemical behaviors of Pt/mischmetal film electrodes

    Institute of Scientific and Technical Information of China (English)

    张文魁; 杨晓光; 马淳安; 王云刚; 余厉阳

    2003-01-01

    The Ml(La-rich mischmetal) films with a thin Pt layer on the substrate of chemically coarsen ITO glassor silicon slices were prepared by magnetic sputtering technique. The crystal structure and surface morphology ofthe films were investigated by X-ray diffraction(XRD) analysis and atomic force microscopy(AFM), respectively.The electrochemical hydridation/dehydridation behaviors of the films in KOH solution were studied by using cyclicvoltammagraph and electrochemical impedance spectrum(EIS) as well. The AFM results show that the Pt cover lay-er on the M1 films is of island structure with a grain of 150 - 200 nm in size. The presence of a thin Pt layer can pro-vide sufficient high electrocatalytic activity for the electrochemical charge-transfer reaction. The electrochemical re-duction and oxidation reaction occur on the Pt layer, and the diffusion of H into the Ml film is the rate-controlledstep. The Pt coatings also act as protective layers, preventing oxidation and/or poisoning of the underlying Ml filmsin air.

  16. Single crystal Fe1-xGax thin films for monolithic microwave devices

    Science.gov (United States)

    Kuanr, Bijoy K.; Camley, R. E.; Celinski, Z.; McClure, Adam; Idzerda, Yves

    2014-05-01

    Modern, high frequency, microwave devices for communications technologies can be made with thin ferromagnetic films with narrow microwave resonance linewidths. Recently, there has been interest in magnetostrictive materials where the material constants can change substantially with stresses and applied magnetic fields. We report the development of single crystal thin (20 nm thick) magnetostrictive films of Fe1-xGax (x = 0.20 FeGa(A), 0.23 FeGa(B), 0.28 FeGa(C) on GaAs(001) substrates and on their use in prototype microwave devices. These Galfenol films have a narrower linewidth than any previously reported similar thin films. We fabricate and characterize novel microstrip-based monolithic microwave devices using Galfenol thin films as an active element. We find a number of important features: (1) There is a large absorption (up to 30 dB/cm) at the resonance frequency. (2) The linewidth of the device is narrow ˜1.5 GHz. (3) The saturation magnetization of the samples decreases with the increase in Ga contents. (4) The cubic anisotropy is close to zero (˜0.06 kOe for FeGa(A)) and becomes negative for higher concentration of Ga content in the samples, and (5) the damping increases with increase in Ga concentration.

  17. Crystal structure and switchable optical properties of yttrium hydride films covered by palladium layer

    Institute of Scientific and Technical Information of China (English)

    张文魁; 甘永平; 杨晓光; 黄辉; 余厉阳

    2003-01-01

    The palladium/yttrium films were prepared using magnetron sputtering technique.The changes of crystal structure,morphology and optical properties of the films during the hydrogen absorption/desorption process were investigated.The results of SEM and AFM analysis show that yttrium films have columnar structure,and the Pd cover layers on the surface of the yttrium films are composed of nanometer-sized Pd particles,which contain a large amount of smaller crystalline grains.During the gas hydrogen absorption/desorption process,YH3 and YH2 hydrides form on the sites of Pd grains contacting with Y grains.Upon hydrogenation,YH3 hydride forms and the switchable optical properties can be observed.The light transparency of the films increases with the increasing of hydrogen loading time and the light wavelength,and the absorption limitation occurs at λ=400 nm.Upon dehydrogenation,YH3 hydride dissociates into YH2 hydride,and the maximum transparency occurs at λ=689 nm.

  18. Wrinkling of a thin film on a nematic liquid-crystal elastomer.

    Science.gov (United States)

    Soni, Harsh; Pelcovits, Robert A; Powers, Thomas R

    2016-07-01

    Wrinkles commonly develop in a thin film deposited on a soft elastomer substrate when the film is subject to compression. Motivated by recent experiments [Agrawal et al., Soft Matter 8, 7138 (2012)]1744-683X10.1039/c2sm25734c that show how wrinkle morphology can be controlled by using a nematic elastomer substrate, we develop the theory of small-amplitude wrinkles of an isotropic film atop a nematic elastomer. The directors of the nematic elastomer are initially uniform. For uniaxial compression of the film along the direction perpendicular to the elastomer directors, the system behaves as a compressed film on an isotropic substrate. When the uniaxial compression is along the direction of nematic order, we find that the soft elasticity characteristic of liquid-crystal elastomers leads to a critical stress for wrinkling which is very small compared to the case of an isotropic substrate. We also determine the wavelength of the wrinkles at the critical stress and show how the critical stress and wavelength depend on substrate depth and the anisotropy of the polymer chains in the nematic elastomer.

  19. Composite Materials and Films Based on Melanins, Polydopamine, and Other Catecholamine-Based Materials

    Directory of Open Access Journals (Sweden)

    Vincent Ball

    2017-07-01

    Full Text Available Polydopamine (PDA is related to eumelanins in its composition and structure. These pigments allow the design, inspired by natural materials, of composite nanoparticles and films for applications in the field of energy conversion and the design of biomaterials. This short review summarizes the main advances in the design of PDA-based composites with inorganic and organic materials.

  20. Screen-Printed Fabrication of PEDOT:PSS/Silver Nanowire Composite Films for Transparent Heaters

    Directory of Open Access Journals (Sweden)

    Xin He

    2017-02-01

    Full Text Available A transparent and flexible film heater was fabricated; based on a hybrid structure of poly(3,4-ethylenedioxythiophene poly(styrenesulfonate (PEDOT:PSS and silver nanowires (Ag NWs using a screen printing; which is a scalable production technology. The resulting film integrates the advantages of the two conductive materials; easy film-forming and strong adhesion to the substrate of the polymer PEDOT:PSS; and high conductivity of the Ag NWs. The fabricated composite films with different NW densities exhibited the transmittance within the range from 82.3% to 74.1% at 550 nm. By applying 40 V potential on the films; a stable temperature from 49 °C to 99 °C was generated within 30 s to 50 s. However; the surface temperature of the pristine PEDOT:PSS film did not increase compared to the room temperature. The composite film with the transmittance of 74.1% could be heated to the temperatures from 41 °C to 99 °C at the driven voltages from 15 V to 40 V; indicating that the film heater exhibited uniform heating and rapid thermal response. Therefore; the PEDOT:PSS/Ag NW composite film is a promising candidate for the application of the transparent and large-scale film heaters.

  1. Effects of the composite nanovesicles on the physical properties and cellular adhesion of chitosan films.

    Science.gov (United States)

    Lionzo, Maria I Z; Lorenzini, Giulia C; Tomedi, Joelson; Pranke, Patricia; Silveira, Nádya P

    2012-04-01

    Chitosan films were prepared by the casting of a chitosan gel in absence and presence of composite nanovesicles. The microscopy images showed the occurrence of agglomerates on the surface and internal pores when the nanovesicles were added to the films, differently from the smooth surface of the pure chitosan films. Despite the hydrophobic character that composite nanovesicles gave to the chitosan films, as showed by the reduction of the water permeation at prolonged times, there was a reduction on the contact angle values for these samples related to the roughness of the surface. The peak of water desorption observed on calorimetric analysis of chitosan was shifted to higher values when the nanovesicles were added to the films. Furthermore, the desappearance of Tg on the films containing nanovesicles denoted their plastifier effect in the chitosan film. The swelling results showed higher water diffusion at the first times for the films containing nanovesicles because of the pores observed by microscopy. However, at prolonged times, there was a reduction on the swelling because of the lipofilic composition of the nanovesicles. Furthermore, the presence of nanovesicles led to a reduction on the water content in the chitosan films. Due to the effect on the physical properties of the chitosan films, the addition of nanovesicles on discrete concentrations contributed to the cell adhesion.

  2. Room temperature synthesis of crystallized luminescent SrWO 4 films by an adjustable galvanic cell method

    Science.gov (United States)

    Cui, Chunhua; Bi, Jian; Gao, Daojiang

    2008-09-01

    Highly crystallized luminescent SrWO 4 films were prepared directly on tungsten substrate in strontium hydroxide aqueous solution by a galvanic cell method without impressed current at room temperature. It is noteworthy that the driving force of galvanic cell method is adjustable by adding different concentrations of oxidant. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results reveal that the crystallized films have a scheelite-type tetragonal structure and homogeneous surface. The film showed single blue emissions at 447 nm with excitation lights of 220, 230, 250, 260 and 270 nm at room temperature, respectively.

  3. Preparation and multicolored fluorescent properties of CdTe quantum dots/polymethylmethacrylate composite films

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yanni; Liu, Jianjun, E-mail: jjliu717@aliyun.com; Yu, Yingchun; Zuo, Shengli

    2015-10-25

    A new simple route was presented for the preparation of stable fluorescent CdTe/polymethylmethacrylate (CdTe/PMMA) composite films by using hydrophilic thioglycolic acid capped CdTe quantum dots (TGA-CdTe QDs) and polymethylmethacrylate (PMMA) as raw materials. The TGA-CdTe QDs were firstly exchanged with n-dodecanethiol (DDT) to become hydrophobic DDT-CdTe QDs via a ligand exchange strategy, and then incorporated into PMMA matrix to obtain fluorescent CdTe/PMMA composite films. The structure and optical properties of DDT-CdTe QDs and CdTe/PMMA composite films were investigated by XRD, IR, UV and PL techniques. The results indicated that the obtained DDT-CdTe QDs well preserved the intrinsic structure and the maximum emission wavelength of the initial water-soluble QDs and the resulting 6.10 wt% CdTe/PMMA composite film exhibited significantly enhanced PL intensity. Furthermore, the multicolored composite films with green, yellow-green, yellow and orange light emissions were well tuned by incorporating the CdTe QDs of various maximum emission wavelengths. The TEM image demonstrated that the CdTe QDs were well-dispersed in the PMMA matrix without aggregation. Superior photostability of QDs in the composite film was confirmed by fluorescence lifetime measurement. Thermo-gravimetric analysis of CdTe/PMMA composite films showed no obvious enhancement of thermal stability compared with pure PMMA. - Highlights: • Ligand-exchange strategy was used to render CdTe QDs oil-soluble. • CdTe QDs were incorporated into PMMA matrix to fabricate fluorescent films. • The resulting 6.10 wt% CdTe/PMMA film exhibited significantly enhanced PL intensity. • Fluorescent colors of films were tuned by varying the λ{sub em} of incorporated CdTe QDs.

  4. Electrochemical properties of polyaniline/carboxydextran (PANI/carDEX) composite films for biofuel cells in neutral aqueous solutions.

    Science.gov (United States)

    Lee, Sunmook; Choi, Bokkyu; Tsutsumi, Atsushi

    2009-06-01

    Electrochemical properties of composite films consisting of polyaniline/carboxydextran (PANI/carDEX) as a biofuel cell electrode platform were investigated. These composite films were formed on a planar gold surface through electropolymerization after a simple chemical modification of dextran with carboxyl groups. Cyclic voltammetry indicated that the composite films retained a redox activity in neutral pH environment. The PANI/carDEX composite films showed an electrocatalytic activity for the oxidation of ascorbic acid. The PANI/carDEX composite films also demonstrated an excellent electron-transfer mediating capability for the bioelectrocatalytic activation of glucose oxidase (GOx) toward the oxidation of glucose.

  5. Carbide Identification in Different Regions of a Thin Metal Film Covering on an HPHT As-Grown Diamond Single Crystal from Ni-Mn-C System

    Institute of Scientific and Technical Information of China (English)

    XU Bin; CUI Jian-Jun; LI Mu-Sen; LI Cheng-Mei; CHU Fu-Min; FENG Li-Ming

    2005-01-01

    @@ Diamond single crystals were synthesized in the presence of Ni-Mn catalyst under high temperature and high pressure (HPHT). A thin metal film covering on as-grown diamond formed during diamond growth was examined using transmission electron microscopy. It was shown that phase compositions of the region near the as-grown diamond are different from those of other regions in the film. We found γ-(Ni,Mn) solid solution, diamond, Ni3C and Mn23C6 in the region near the as-grown diamond, while graphite, Mn7C3 and γ-(Ni,Mn) could be found in other regions of the film. The relationship between the diamond growth and the carbides in the film was analysed briefly. It is suggested that the carbon source for diamond growth should be closely related to the decomposition of carbides in the region near the diamond single crystal at HPHT, not being directly from that of the graphite structure.

  6. Effect of deposition temperature on electron-beam evaporated polycrystalline silicon thin-film and crystallized by diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Yun, J., E-mail: j.yun@unsw.edu.au; Varalmov, S.; Huang, J.; Green, M. A. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052 (Australia); Kim, K. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052 (Australia); Suntech R and D Australia, Botany, New South Wales 2019 (Australia)

    2014-06-16

    The effects of the deposition temperature on the microstructure, crystallographic orientation, and electrical properties of a 10-μm thick evaporated Si thin-film deposited on glass and crystallized using a diode laser, are investigated. The crystallization of the Si thin-film is initiated at a deposition temperature between 450 and 550 °C, and the predominant (110) orientation in the normal direction is found. Pole figure maps confirm that all films have a fiber texture and that it becomes stronger with increasing deposition temperature. Diode laser crystallization is performed, resulting in the formation of lateral grains along the laser scan direction. The laser power required to form lateral grains is higher in case of films deposited below 450 °C for all scan speeds. Pole figure maps show 75% occupancies of the (110) orientation in the normal direction when the laser crystallized film is deposited above 550 °C. A higher density of grain boundaries is obtained when the laser crystallized film is deposited below 450 °C, which limits the solar cell performance by n = 2 recombination, and a performance degradation is expected due to severe shunting.

  7. STUDIES ON THE MECHANICAL PROPERTIES AND CRYSTALLIZATION BEHAVIOR OF POLYETHYLENE COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    ZHU Jin; OU Yuchun; FENG Yupeng

    1995-01-01

    The effects of interfacial modifier on the mechanical, dynamic mechanical properties and crystallization behavior of the polyethylene composites were investigated in the present paper.It was found that the interfacial modifer significantly improved the mechanical properties,influenced the dynamic mechanical spectra and slightly changed the crystallization behavior.The results showed that the interfacial modifier changed the dispersion state of dispersed phase of the composites, resulting in different phase structure, which was the major reason leading to different mechanical and crystallization properties.

  8. Crystallization behavior during transparent In{sub 2}O{sub 3}-ZnO film growth

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Junjun; Nakamura, Shin-ichi; Shigesato, Yuzo [Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258 (Japan)

    2016-09-15

    Structural evolution of transparent conductive In{sub 2}O{sub 3}-ZnO (IZO) films with increasing substrate temperature during sputtering was studied using transmission electron microscopy (TEM) and spectroscopic ellipsometry. Increasing the substrate temperature can induce film crystallization in the initial growth stage, and enhance the crystallization of IZO films. Extensive simulations using ellipsometry data demonstrated a decrease in the crystallization rate for IZO films deposited between 200 and 300 C, which is attributed to the influence of the interference between nearby growing grains. TEM observations also reveal that the growth competition between different crystallites leads to an increase in the lateral grain size with increasing substrate temperature. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Preparation and characterization of keratin and chicken egg white-templated luminescent Au cluster composite film

    Science.gov (United States)

    Xing, Yao; Liu, Hongling; Yu, Weidong

    2016-02-01

    The characterization of keratin-chicken egg white-templated luminescent Au cluster composite films were studied using fourier-transform infrared spectroscopy (FTIR) to demonstrate and quantify the secondary transformation of composite films. The results showed that the secondary structure of treated films was transformed from disordered structure to ordered conformation including α-helix conformation and β-pleated-sheet conformation due to the increase of protein-templated luminescent Au cluster. The absorption features of treated films were exhibited by the UV-vis spectra. The bule-shift and decreased intensity indicated the change of microenvironment due to the concentration of protein-templated luminescent Au cluster. The transmission electron microscopy images of composite films supported the aggregation resulting from microenvironment. The effect of protein-templated luminescent Au cluster was characterized by the laser scanning confocal microscope (LSCM) images which showed the gradually intensive luminescence with increasing Au cluster and the transformation from the whiskers to nanoparticle.

  10. The nanoindentation applied to predict the interface delamination for the C/amorphous Si composite film

    Science.gov (United States)

    Han, Chang-Fu; Huang, Chao-Yu; Wu, Bo-Hsiung; Lin, Jen-Fin

    2009-10-01

    In the present study, the indentation depth corresponding to the pop-in arising in the loading process is found to be quite close to the C/amorphous Si composite film thickness, regardless of the C-film thickness. This load-depth behavior gives a clue that the occurrence of pop-in is perhaps related to the buckling of the composite film, which had already delaminated from the silicon substrate. This indentation depth of buckling predicted by the present model is quite close to the pop-in depth obtained from experimental results, regardless of the change in the C-film thickness. This characteristic reveals that the present model is developed successfully to predict the pop-in depth of a specimen, and the pop-in is indeed created due to the buckling of the composite film under a compression stress.

  11. Composite films of poly(vinyl alcohol)-chitosan-bacterial cellulose for drug controlled release.

    Science.gov (United States)

    Pavaloiu, Ramona-Daniela; Stoica-Guzun, Anicuta; Stroescu, Marta; Jinga, Sorin Ion; Dobre, Tanase

    2014-07-01

    Mono and multilayer composite films of poly(vinyl alcohol)-chitosan-bacterial cellulose (PVA/chitosan/BC) have been prepared to achieve controlled release of ibuprofen sodium salt (IbuNa) as model drug. The composite films have been characterized by Fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Surface morphology was investigated by scanning electron microscopy (SEM). Equilibrium swelling was measured in water at two different pH values and in vitro release of IbuNa in pH 1.2 and pH 7.4 media was studied. The release experiments revealed that drug release is pH sensitive. The release kinetics of IbuNa could be described by the Fickian model of diffusion with a good agreement. The IbuNa release rate was decreasing for all the films as the BC concentration was increased in the films composition, the decrease being higher for the multilayer films.

  12. Fabrication for multilayered composite thin films by dual-channel vacuum arc deposition.

    Science.gov (United States)

    Dai, Hua; Shen, Yao; Wang, Jing; Xu, Ming; Li, Liuhe; Li, Xiaoling; Cai, Xun; Chu, Paul K

    2008-06-01

    A flexible dual-channel curvilinear electromagnetic filter has been designed and constructed to fabricate multilayered composite films in vacuum arc ion plating. The filter possesses two guiding channels and one mixing unit. Multilayered TiN/AlN and TiAlN composite films can be produced by controlling the frequency or interval of the two cathodes. The x-ray photoelectron spectroscopy and low-angle x-ray diffraction results reveal the periodic Ti and Al structures in the TiN/AlN films. The TiAlN films exhibit a smooth surface morphology confirming effective filtering of macroparticles by the filter. High temperature oxidation conducted at 700 degrees C for an hour indicates that the weight increment in the TiAlN films produced by the dual filter is only half of that of the TiAlN films produced without a filter, thereby showing better resistance against surface oxidation.

  13. Fabrication for multilayered composite thin films by dual-channel vacuum arc deposition

    Science.gov (United States)

    Dai, Hua; Shen, Yao; Wang, Jing; Xu, Ming; Li, Liuhe; Li, Xiaoling; Cai, Xun; Chu, Paul K.

    2008-06-01

    A flexible dual-channel curvilinear electromagnetic filter has been designed and constructed to fabricate multilayered composite films in vacuum arc ion plating. The filter possesses two guiding channels and one mixing unit. Multilayered TiN /AlN and TiAlN composite films can be produced by controlling the frequency or interval of the two cathodes. The x-ray photoelectron spectroscopy and low-angle x-ray diffraction results reveal the periodic Ti and Al structures in the TiN /AlN films. The TiAlN films exhibit a smooth surface morphology confirming effective filtering of macroparticles by the filter. High temperature oxidation conducted at 700°C for an hour indicates that the weight increment in the TiAlN films produced by the dual filter is only half of that of the TiAlN films produced without a filter, thereby showing better resistance against surface oxidation.

  14. Tailoring the Composition and Properties of Sprayed CuSbS2 Thin Films by Using Polymeric Additives

    Directory of Open Access Journals (Sweden)

    Ionut Popovici

    2012-01-01

    Full Text Available CuSbS2 thin films were obtained by spray pyrolysis deposition, using polymeric additives for controlling the surface properties and film’s composition. Ternary crystalline chalcostibite compounds have been obtained without any postdeposition treatments. XRD spectra and IR spectroscopy were used to characterize films composition and interactions between components. Films morphology and surface energy were investigated using AFM microscopy and contact angle measurements. Hydrophobic and hydrophilic polymers strongly influence the composition and film morphology.

  15. Morphological and mechanical characterization of composite calcite/SWCNT-COOH single crystals.

    Science.gov (United States)

    Calvaresi, Matteo; Falini, Giuseppe; Pasquini, Luca; Reggi, Michela; Fermani, Simona; Gazzadi, Gian Carlo; Frabboni, Stefano; Zerbetto, Francesco

    2013-08-01

    A growing number of classes of organic (macro)molecular materials have been trapped into inorganic crystalline hosts, such as calcite single crystals, without significantly disrupting their crystalline lattices. Inclusion of an organic phase plays a key role in enhancing the mechanical properties of the crystals, which are believed to share structural features with biogenic minerals. Here we report the synthesis and mechanical characterization of composite calcite/SWCNT-COOH single crystals. Once entrapped into the crystals SWCNT-COOH appeared both as aggregates of entangled bundles and nanoropes. Their observation was possible only after crystal etching, fracture or FIB (focused ion beam) cross-sectioning. SWCNT-COOHs occupied a small volume fraction and were randomly distributed into the host crystal. They did not strongly affect the crystal morphology. However, although the Young's modulus of composite calcite/SWCNT-COOH single crystals was similar to that of pure calcite their hardness increased by about 20%. Thus, SWCNT-COOHs provide an obstacle against the dislocation-mediated propagation of plastic deformation in the crystalline slip systems, in analogy with the well-known hardness increase in fiber-reinforced composites.

  16. Effect of Continuous Multi-Walled Carbon Nanotubes on Thermal and Mechanical Properties of Flexible Composite Film.

    Science.gov (United States)

    Cha, Ji Eun; Kim, Seong Yun; Lee, Seung Hee

    2016-10-12

    To investigate the effect of continuous multi-walled carbon nanotubes (MWCNTs) on the thermal and mechanical properties of composites, we propose a fabrication method for a buckypaper-filled flexible composite film prepared by a two-step process involving buckypaper fabrication using vacuum filtration of MWCNTs, and composite film fabrication using the dipping method. The thermal conductivity and tensile strength of the composite film filled with the buckypaper exhibited improved results, respectively 76% and 275% greater than those of the individual MWCNT-filled composite film. It was confirmed that forming continuous MWCNT fillers is an important factor which determines the physical characteristics of the composite film. In light of the study findings, composite films using buckypaper as a filler and polydimethylsiloxane (PDMS) as a flexible matrix have sufficient potential to be applied as a heat-dissipating material, and as a flexible film with high thermal conductivity and excellent mechanical properties.

  17. Effect of Continuous Multi-Walled Carbon Nanotubes on Thermal and Mechanical Properties of Flexible Composite Film

    Directory of Open Access Journals (Sweden)

    Ji Eun Cha

    2016-10-01

    Full Text Available To investigate the effect of continuous multi-walled carbon nanotubes (MWCNTs on the thermal and mechanical properties of composites, we propose a fabrication method for a buckypaper-filled flexible composite film prepared by a two-step process involving buckypaper fabrication using vacuum filtration of MWCNTs, and composite film fabrication using the dipping method. The thermal conductivity and tensile strength of the composite film filled with the buckypaper exhibited improved results, respectively 76% and 275% greater than those of the individual MWCNT-filled composite film. It was confirmed that forming continuous MWCNT fillers is an important factor which determines the physical characteristics of the composite film. In light of the study findings, composite films using buckypaper as a filler and polydimethylsiloxane (PDMS as a flexible matrix have sufficient potential to be applied as a heat-dissipating material, and as a flexible film with high thermal conductivity and excellent mechanical properties.

  18. Electro-optical effects in porous PET films filled with liquid crystal: new possibilities for fiber optics and THZ applications.

    Science.gov (United States)

    Chopik, A; Pasechnik, S; Semerenko, D; Shmeliova, D; Dubtsov, A; Srivastava, A K; Chigrinov, V

    2014-03-15

    The results of investigation of electro-optical properties of porous polyethylene terephthalate films filled with a nematic liquid crystal (5 CB) are presented. It is established that the optical response of the samples on the applied voltage drastically depends on the frequency range. At low frequencies of applied electrical field (foptical response arises as an impulse of light intensity, which decays for the time essentially shorter than the electric pulse duration. At high frequencies (f>fc) electric field induces an overall change in the light intensity, which is typical for an electro-optical response of a liquid crystal (LC) layer in a conventional "sandwich"-like cell. The dependences of critical frequency fc, threshold voltages, and characteristic times on a pore diameter d were established. The peculiarities of electro-optical effects can be explained in the framework of the approach which connects the variations of light intensity with the corresponding changes of the effective refractive index n(eff) of a composite LC media. The unusual behavior of the electro-optical response at low frequencies is assigned to the orienting action of the specific shear flow typical for electrokinetic phenomena in polar liquids.

  19. XPS Observations of Crystal Field Splitting in TiO2 Thin Films in Quantum Confinement Approach

    Science.gov (United States)

    Sushkova, Natalya

    2015-03-01

    Transition metal oxides attract increased interest due to amazing electrical and magnetic properties and their outstanding applications designated by relative d-band redistributions that are shifted in such a way that narrow bands arranged by localized electrons are situated in the vicinity of EF. Different kinds of lattice distortions caused by doping and/or quantum size confinement of TM oxides are assigned to remarkable phenomenon Mott metal-insulator transitions, when mutual metal-oxide orbital arrangement changes dramatically. There is a widespread consensus that strong electron correlations are responsible for that change and magnetic excitation is one of manifestations of these correlations. Here we are presenting XPS study of titanium dioxide nanocrystal formations on silicon substrate with native oxide. The dynamic changes in XPS spectra were used for analysis of TiO2 thin films with mass thicknesses up to 2 monolayers formed by redox reactions of sputtered Ti on Si(100) substrate with native oxide implemented in situ under UHV conditions. XPS spectra evolution, as a traditional source of information on phase composition, was complemented by the possibility to estimate the morphology and crystal field splitting of formed precipitates. Intensity fluctuations observed for O1s, Si 2p, Ti2p spectra were accompanied by crystal field splitting in Ti2p and on second derivatives of O1s. These fluctuations were followed by noticeable changes in the vicinity of band gap indicating possible Mott metal-insulator transitions.

  20. Preparation and characterization of polyimide/silica/silver composite films

    Institute of Scientific and Technical Information of China (English)

    Ning LUO; Zhanpeng WU; Nanxiang MOU; Lizhong JIANG; Dezhen WU

    2008-01-01

    Polyimide/silica/silver hybrid films were pre-pared by the sol-gel method combined with in situ single-stage self-metallization technique.The structure of polyi-mide films in the thermal curing process and the influence of silica content on the migration and aggregation of silver particles to the surface of hybrid films were investigated.The hybrid films were characterized by transmission elec-tron microscopy,dynamic mechanical thermal analysis,Fourier transform infrared spectroscopy,ultraviolet visible spectroscopy and mechanical measurements.The results indicated that there was no degradation of the polyimide matrix after the formation of silica and silver particles.Silica acted as the nucleus for the silver particles.With increasing silica content,more and more silver particles were kept in the hybrid films instead of being migrated onto the surface of the hybrid films and the reflections of hybrid films decreased gradually.

  1. Polymer compositions, polymer films and methods and precursors for forming same

    Science.gov (United States)

    Klaehn, John R; Peterson, Eric S; Orme, Christopher J

    2013-09-24

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  2. Crystal orientation mapping applied to the Y-TZP/WC composite

    CERN Document Server

    Faryna, M; Sztwiertnia, K

    2002-01-01

    Crystal orientation measurements made by electron backscattered diffraction (EBSD) in the scanning electron microscope (SEM) and microscopic observations provided the basis for a quantitative investigation of microstructure in an yttria stabilized, tetragonal zirconia-based (Y-TZP) composite. Automatic crystal orientation mapping (ACOM) in a SEM can be preferable to transmission electron microscopy (TEM) for microstructural characterization, since no sample thinning is required, extensive crystal data is already available, and the analysis area is greatly increased. A composite with a 20 vol.% tungsten carbide (WC) content was chosen since it revealed crystal relationships between the matrix and carbide phase already established by TEM analysis. However, this composite was difficult to investigate in the EBSD/ SEM since it is non-conductive, the Y-TZP grain size is of the order of the system resolution, and the sample surface, though carefully prepared, reveals a distinctive microtopography. In this paper, so...

  3. A Photonic Crystal Laser from Solution Based Organo-Lead Iodide Perovskite Thin Films.

    Science.gov (United States)

    Chen, Songtao; Roh, Kwangdong; Lee, Joonhee; Chong, Wee Kiang; Lu, Yao; Mathews, Nripan; Sum, Tze Chien; Nurmikko, Arto

    2016-04-26

    Perovskite semiconductors are actively investigated for high performance solar cells. Their large optical absorption coefficient and facile solution-based, low-temperature synthesis of thin films make perovskites also a candidate for light-emitting devices across the visible and near-infrared. Specific to their potential as optical gain medium for lasers, early work has demonstrated amplified spontaneous emission and lasing at attractively low thresholds of photoexcitation. Here, we take an important step toward practically usable perovskite lasers where a solution-processed thin film is embedded within a two-dimensional photonic crystal resonator. We demonstrate high degree of temporally and spatially coherent lasing whereby well-defined directional emission is achieved near 788 nm wavelength at optical pumping energy density threshold of 68.5 ± 3.0 μJ/cm(2). The measured power conversion efficiency and differential quantum efficiency of the perovskite photonic crystal laser are 13.8 ± 0.8% and 35.8 ± 5.4%, respectively. Importantly, our approach enables scalability of the thin film lasers to a two-dimensional multielement pixelated array of microlasers which we demonstrate as a proof-of-concept for possible projection display applications.

  4. Thermal stimulated current response in cupric oxide single crystal thin films over a wide temperature range

    Science.gov (United States)

    Yang, Kungan; Wu, Shuxiang; Yu, Fengmei; Zhou, Wenqi; Wang, Yunjia; Meng, Meng; Wang, Gaili; Zhang, Yueli; Li, Shuwei

    2017-01-01

    Cupric oxide single crystal thin films (~26 nm) were grown by plasma-assisted molecular beam epitaxy. X-ray diffraction, Raman spectra and in situ reflection high-energy electron diffraction show that the thin films are 2  ×  2 reconstructed with an in-plane compression and out-of-plane stretching. A thermal stimulated current measurement indicates that the electric polarization response is shown in the special 2D cupric oxide single crystal thin film over a wide temperature range from 130 K to near-room temperature. We infer that the abnormal electric response involves the changing of phase transition temperature induced by structure distortion, the spin frustration and the magnetic fluctuation effect of a short-range magnetic order, or the combined action of both of the two factors mentioned above. This work suggests a promising clue for finding new room temperature single phase multiferroics or tuning phase transition temperatures.

  5. Turbulence-induced melting of a nonequilibrium vortex crystal in a forced thin fluid film

    CERN Document Server

    Perlekar, Prasad

    2009-01-01

    To develop an understanding of recent experiments on the turbulence-induced melting of a periodic array of vortices in a thin fluid film, we perform a direct numerical simulation of the two-dimensional Navier-Stokes equations forced such that, at low Reynolds numbers, the steady state of the film is a square lattice of vortices. We find that, as we increase the Reynolds number, this lattice undergoes a series of nonequilibrium phase transitions, first to a crystal with a different reciprocal lattice and then to a sequence of crystals that oscillate in time. Initially the temporal oscillations are periodic; this periodic behaviour becomes more and more complicated, with increasing Reynolds number, until the film enters a spatially disordered nonequilibrium statistical steady that is turbulent. We study this sequence of transitions by using fluid-dynamics measures, such as the Okubo-Weiss parameter that distinguishes between vortical and extensional regions in the flow, ideas from nonlinear dynamics, e.g., \\Poi...

  6. Periodic reversal of magneto-optic Faraday rotation on uniaxial birefringence crystal with ultrathin magnetic films

    Directory of Open Access Journals (Sweden)

    C. W. Su

    2013-07-01

    Full Text Available An experimental approach of inclined incidence magneto-optic Faraday effect observed in the polar plane is applied. Three samples containing ferromagnetic cobalt ultrathin films on a semiconductor zinc oxide (0001 single crystal substrate with in-plane and out-of-plane anisotropy are evaluated. Through the fine adjustment of crossed polarizers in the magneto-optic effect measurement completely recorded the detail optical and magneto-optical responses from the birefringent crystal substrate and the magnetic film, especially for the signal induced from the substrate with uniaxial optical axis. The angle dependency of interference phenomena periodically from the optical and magneto-optical responses is attributed to the birefringence even in the absence of a magnetic field. The new type of observation finds that the transmission Faraday intensity in the oblique incidence includes a combination of polarization rotations, which results from optical compensation from the substrate and magneto-optical Faraday effects from the film. The samples grown at different rates and examined by this method exhibit magnetic structure discriminations. This result can be applied in the advanced polarized-light technologies to enhance the spatial resolution of magnetic surfaces with microstructural information under various magnetic field direction.

  7. Preparation of polyimide/Al{sub 2}O{sub 3} composite films as improved solid dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Alias, Asliza; Ahmad, Z. [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Ismail, A.B., E-mail: badri@eng.usm.my [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia)

    2011-06-15

    Highlights: > We prepare and characterize polyimide-alumina composite as solid dielectric. > Prolong the curing time at low temperature reduces the composite s shrinkage problem. > Dielectric constant increases with the increase of alumina content. > Thermal properties is improved with the addition of alumina. - Abstract: Considerable demand for solid thin-film dielectrics with high dielectric constants for use in the fabrication of capacitors has been observed. In this study, polyimide (PI)/Al{sub 2}O{sub 3} composite films were prepared by incorporating different micron-sized {alpha}-Al{sub 2}O{sub 3} contents into PI derived from pyromellitic dianyhydride and 4,4'-oxydianiline via ultrasonication. Chemical structure, morphology, dielectric and thermal properties were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), LCR meter and Perkin Elmer Pyris 6. FTIR spectra showed complete imidization, and all characteristic peaks of the imide groups are observed in PI and PI/Al{sub 2}O{sub 3} composite films. XRD patterns revealed that the PI/Al{sub 2}O{sub 3} composite exhibits peaks similar to those of {alpha}-Al{sub 2}O{sub 3}, indicating that the crystal structure of {alpha}-Al{sub 2}O{sub 3} remains unchanged and stable after being doped into the PI matrix. SEM micrographs showed uniform distribution of {alpha}-Al{sub 2}O{sub 3} particles in the PI matrix. Meanwhile, the dielectric constant, dielectric loss and thermal stability of PI/Al{sub 2}O{sub 3} increases with the addition of {alpha}-Al{sub 2}O{sub 3} content.

  8. Raman scattering in LiCoO{sub 2} single crystals and thin films

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, J.D.; Fu, M.L.; Trickett, D.M.; McGraw, J.M.; Ciszek, T.F.; Parilla, P.A.; Rogers, C.T.; Ginley, D.S.

    1998-07-01

    While LiCoO{sub 2} is one of the most promising cathode materials for rechargeable Li-ion batteries, many questions persist regarding the interrelationship of the electronic, structural and battery properties. The authors report Raman scattering measurements for uniaxially textured and randomly oriented polycrystalline LiCoO{sub 2} thin films as well as for LiCoO{sub 2} and LiCo{sub 0.4}Al{sub 0.6}O{sub 2} single crystals. For both the crystalline LiCoO{sub 2} thin film samples and the single crystal LiCoO{sub 2} samples, well defined phonon modes are observed at Raman shifts of 486 cm{sup {minus}1} and 596 cm{sup {minus}1} corresponding to the expected E{sub g} and A{sub 1g} modes of the layered LiCoO{sub 2} crystal structure with R{bar 3}m symmetry. Upon Al substitution for Co in LiCoO{sub 2}, the two phonon modes appear to shift to higher energy, but further work is needed to clarify this point.

  9. Correlation of the crystal orientation and electrical properties of silicon thin films on glass crystallized by line focus diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Yun, J., E-mail: j.yun@unsw.edu.au [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Huang, J.; Teal, A. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Kim, K. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Suntech R& D Australia, Botany, NSW 2019 (Australia); Varlamov, S.; Green, M.A. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2016-06-30

    In this work, crystallographic orientation of polycrystalline silicon films on glass formed by continuous wave diode laser crystallization was studied. Most of the grain boundaries were coincidence lattice Σ3 twin boundaries and other types of boundaries such as, Σ6, Σ9, and Σ21 were also frequently observed. The highest photoluminescence signal and mobility were observed for a grain with (100) orientation in the normal direction. X-ray diffraction results showed the highest occupancies between 41 and 70% along the (110) orientation. However, the highest occupancies changed to (100) orientation when a 100 nm thick SiO{sub x} capping layer was applied. Suns-Voc measurement and photoluminescence showed that higher solar cell performance is obtained from the cell crystallized with the capping layer, which is suspected from increased occupancies of (100) orientation. - Highlights: • Linear grains parallel to the scan direction formed with high density. • Σ3 coincidence lattice (CSL) boundaries found inside a grain • Grain boundaries exhibit various CSL boundaries such as Σ9, Σ18, and Σ27. • Grain with < 100 > orientation in normal direction showed highest electrical properties. • Improved voltage observed when percentage of < 100 > normal orientation is increased.

  10. Fully automatic spray-LBL machine with monitoring the real time growth of multilayer films using Quartz Crystal Microbalance

    Directory of Open Access Journals (Sweden)

    Shiratori S.

    2013-08-01

    Full Text Available A fully automatic spray-LBL machine with monitoring the real time growth of multilayer films using Quartz Crystal Microbalance (QCM techniques was newly developed. We established fully automatic spray layer-by-layer method by precisely controlling air pressure, solution flow, and spray pattern. The movement pattern towards the substrate during solution spraying allowed fabrication of a nano-scale, flat, thin film over a wide area. Optimization of spray conditions permitted fabrication of the flat film with high and low refractive indexes, and they were piled up alternatively to constitute a one-dimensional photonic crystal with near-infrared reflection characteristics. The heat shield effect of the near-infrared reflective film was also confirmed under natural sunlight. It was demonstrated that the fabrication using the automatic spray-LBL machine and real-time QCM monitoring allows the fabrication of optical quality thin films with precise thickness.

  11. Optimization of composition and crystal structure for processing route of PZT system

    Energy Technology Data Exchange (ETDEWEB)

    Kakimoto, K.; Kakemoto, H.; Fujita, S.; Masuda, Y. [Hachinohe Inst. of Tech., Aomori (Japan). JSPS Research Project

    2002-07-01

    An evaluation procedure that employs by calibrated X-ray fluorescence (XRF) analysis of the chemical composition of PZT bulk ceramics and thin films deposited on Si-based substrate by the pulsed laser deposition (PLD) technique has been established. The plots of cation fraction and XRF intensity for Pb, Zr and Ti atoms were curve-fitted using the results obtained by XRF measurement of normalized PZT samples whose compositions were selected from those near the morphotropic phase boundary (MPB) of PZT(Zr/Ti=53/47). While the Pb curve was almost linear, Zr and Ti yielded parabolic curves due to the effect of matrix Pb. In the case of thin-film analysis, the substrate beneath the thin film exerted a matrix effect on the quantitative analysis of the thin film. Both the coexisting element effect and the substrate effect were calibrated to prepare an excellent XRF table for the precise quantitative analysis of PZT thin films. The present XRF table quantitatively revealed a variation in PZT composition during the high-temperature sintering process of bulk and even its thin-film prepared by PLD. The combination of X-ray diffraction (XRD) with model calculation also supported quantitative XRF analysis of the compositional difference from Pb stoichiometry. (orig.)

  12. Electrical and Dielectric Properties of Exfoliated Graphite/Polyimide Composite Films with Low Percolation Threshold

    Science.gov (United States)

    Yu, Li; Zhang, Yi-He; Shang, Jiwu; Ke, Shan-Ming; Tong, Wang-shu; Shen, Bo; Huang, Hai-Tao

    2012-09-01

    Exfoliated graphite/polyimide composite films were synthesized by in situ polymerization. The electrical and dielectric properties of composite films with different volume fraction of exfoliated graphite were investigated over the frequency range from 103 Hz to 3 × 106 Hz. The dielectric behavior of the composite films was investigated by percolation theory and a microcapacitor model. A low percolation threshold f c ≈ 3.1 vol.% was obtained due to the high aspect ratio of the exfoliated graphite. Both the dielectric constant and alternating-current (AC) conductivity showed an abrupt increase in the vicinity of the percolation threshold. The ultralarge enhancement of the dielectric constant near and beyond the percolation threshold was due to Maxwell-Wagner-Sillars (MWS) interfacial polarization between the exfoliated graphite and polyimide and interface polarization between the composite film and electrode.

  13. One-step synthesis of PbSe-ZnSe composite thin film

    Science.gov (United States)

    2011-01-01

    This study investigates the preparation of PbSe-ZnSe composite thin films by simultaneous hot-wall deposition (HWD) from multiple resources. The XRD result reveals that the solubility limit of Pb in ZnSe is quite narrow, less than 1 mol%, with obvious phase-separation in the composite thin films. A nanoscale elemental mapping of the film containing 5 mol% PbSe indicates that isolated PbSe nanocrystals are dispersed in the ZnSe matrix. The optical absorption edge of the composite thin films shifts toward the low-photon-energy region as the PbSe content increases. The use of a phase-separating PbSe-ZnSe system and HWD techniques enables simple production of the composite package. PMID:21711822

  14. One-step synthesis of PbSe-ZnSe composite thin film

    Directory of Open Access Journals (Sweden)

    Abe Seishi

    2011-01-01

    Full Text Available Abstract This study investigates the preparation of PbSe-ZnSe composite thin films by simultaneous hot-wall deposition (HWD from multiple resources. The XRD result reveals that the solubility limit of Pb in ZnSe is quite narrow, less than 1 mol%, with obvious phase-separation in the composite thin films. A nanoscale elemental mapping of the film containing 5 mol% PbSe indicates that isolated PbSe nanocrystals are dispersed in the ZnSe matrix. The optical absorption edge of the composite thin films shifts toward the low-photon-energy region as the PbSe content increases. The use of a phase-separating PbSe-ZnSe system and HWD techniques enables simple production of the composite package.

  15. Preparation and properties of biodegradable films from Sterculia urens short fiber/cellulose green composites.

    Science.gov (United States)

    Jayaramudu, J; Reddy, G Siva Mohan; Varaprasad, K; Sadiku, E R; Sinha Ray, S; Varada Rajulu, A

    2013-04-02

    The development of commercially viable "green products", based on natural resources for the matrices and reinforcements, in a wide range of applications, is on the rise. The present paper focuses on Sterculia urens short fiber reinforced pure cellulose matrix composite films. The morphologies of the untreated and 5% NaOH (alkali) treated S. urens fibers were observed by SEM. The effect of 5% NaOH treated S. urens fiber (5, 10, 15 and 20% loading) on the mechanical properties and thermal stability of the composites films is discussed. This paper presents the developments made in the area of biodegradable S. urens short fiber/cellulose (SUSF/cellulose) composite films, buried in the soil and later investigated by the (POM), before and after biodegradation has taken place. SUSF/cellulose composite films have great potential in food packaging and for medical applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Poly(lactic acid) and Osage Orange Wood Fiber Composites for Agricultural Mulch Films

    Science.gov (United States)

    Osage orange wood(OO)was combined with poly(lactic acid)(PLA)to form a polymer composite intended for use as an agricultural mulch film. The PLA-OO mechanical properties were comparable to existing mulch film products and had the advantage of being completely biodegradable through a single growing ...

  17. Photoconductivity of Polymer Composite Films Containing an Mn(III)/Cu(II) Complex

    Science.gov (United States)

    Davidenko, N. A.; Kokozay, V. N.; Petrusenko, S. R.; Stetsyuk, O. N.; Studzinsky, S. L.; Davidenko, I. I.

    2013-11-01

    We have studied the optical, photoelectric and dielectric properties of polymer composite films based on polyvinyl butyral with additives of a mixed-metal Mn(III)/Cu(II) complex. We observed high photoconductivity of the films obtained in the region of absorption by the complex. The slow photocurrent rise and relaxation kinetics are connected with the low mobility of the photogenerated charge carriers.

  18. Diatomite as a novel composite ingredient for chitosan film with enhanced physicochemical properties.

    Science.gov (United States)

    Akyuz, Lalehan; Kaya, Murat; Koc, Behlul; Mujtaba, Muhammad; Ilk, Sedef; Labidi, Jalel; Salaberria, Asier M; Cakmak, Yavuz Selim; Yildiz, Aysegul

    2017-09-01

    Practical applications of biopolymers in different industries are gaining considerable increase day by day. But still, these biopolymers lack important properties in order to meet the industrial demands. In the same regard, in the current study, chitosan composite films are produced by incorporating diatomite soil at two different concentrations. In order to obtain a homogeneous film, glutaraldehyde was supplemented to chitosan solution as a cross-linker. Compositing diatomaceous earth to chitosan film resulted in improvement of various important physicochemical properties compared to control such as; enhanced film wettability, increase elongation at break and improved thermal stability (264-277°C). The microstructure of the film was observed to haveconsisted of homogeneously distributed blister-shaped structures arised due to the incorporation of diatomite. The incorporation of diatomite did not influence the overall antioxidant activity of the composite films, which can be ascribe to the difficulty radicals formation. Chitosan film incorporated with increasing fraction of diatomite revealed a notable enhancement in the antimicrobial activity. Additionally with the present study, for the first time possible interactions between chitosan/diatomite were determined via quantum chemical calculations. Current study will be helpful in giving a new biotechnological perspective to diatom in terms of its successful application in hydrophobic composite film production. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Effect of compatibilization and reprocessing on the isothermal crystallization kinetics of polypropylene/wood flour composites

    Directory of Open Access Journals (Sweden)

    Arieny Rodrigues

    2013-01-01

    Full Text Available Numerous studies have focused on polymer mixtures aimed at the potential applications of these materials. This work analyzed the effect of polymer reprocessing and the type and concentration of compatibilizer on the isothermal crystallization kinetics of polypropylene/wood flour composites. The composites, which were polypropylene grafted with acrylic acid (PP-g-AA and maleic anhydride (PP-g-MA, were processed in a twin screw extruder with and without compatibilizer. Reprocessed polypropylene reached complete crystallization in less time than the composites with virgin polypropylene. The addition of wood flour to the composites did not change the kinetics significantly compared to that of the pure polymers, but the compatibilizers did, particularly PP-g-AA. The nucleation exponent (n and crystallization rate (K were calculated from Avrami plots. The values of n ranged from 2 to 3, indicating instantaneous to sporadic nucleation. The crystallization half-time of reprocessed polypropylene was shorter than that of virgin polypropylene and of the compositions containing PP-g-AA compatibilizer. The activation energy of crystallization and the equilibrium melting temperature were calculated, respectively, from Arrhenius and Hoffman-Weeks plots. Both of these parameters showed lower values in the composites, particularly in the ones containing compatibilizers.

  20. Crystal origins and magmatic system beneath Ngauruhoe volcano (New Zealand) revealed by plagioclase textures and compositions

    Science.gov (United States)

    Coote, Alisha C.; Shane, Phil

    2016-09-01

    The textural variation and compositional zoning of plagioclase in pre-historic and historic basaltic andesite lava flows from Ngauruhoe volcano reveals extensive crystal recycling from a multi-level magma system. Most phenocrysts have a calcic (~ An80-90) resorbed core with diffuse or no zonation that is depleted in Fe and Mg. Some cores display patchy zonation from replacement by high An crystallization prior to resorption. The cores are mantled by oscillatory-zoned rims of lower An content (Mg. Rim zones vary in relative thickness and textural complexity, and include sieve-textured bands, and/or cyclic calcic growth following dissolution events. A subordinate crystal population display similar features, but lack a resorbed core. These latter crystals display overall rimward enrichment in An, Fe and Mg. The resorbed cores crystallized from magmas more mafic than those erupted at Ngauruhoe, and slow cooling and prolonged storage resulted in loss of An zoning patterns and depletion of Fe and Mg by diffusion. These crystals are likely to have originated from deep cumulates or intrusions, and were subsequently entrained in ascending magmas. Patchy-textured cores were produced during decompression in a water under-saturated magma and staged ascent. The diversity in crystal cores reflect different conduits and ascent histories. The crystal rims grew in a more differentiated magma reservoir, and are in equilibrium with the erupted melt. Most of the zoning patterns in the rim zone require water pressure and/or temperature changes. These changes could have been caused by convective self-mixing in a closed system and/or the intrusion of hydrous melts of similar bulk composition. Other crystals display rimward elemental enrichments consistent with mafic recharge. Previously reported rimward enrichment in 87Sr-86Sr compositions can be explained by the re-cycled origin of the crystal cores and progressive crustal assimilation at shallower depths in the magma system where

  1. The preparation, characterization and evaluation of regenerated cellulose/collagen composite hydrogel films.

    Science.gov (United States)

    Cheng, Yongmei; Lu, Jinting; Liu, Shilin; Zhao, Peng; Lu, Guozhong; Chen, Jinghua

    2014-07-17

    Porous structured regenerated cellulose films were oxidized by periodate oxidation to obtain 2,3-dialdehyde cellulose (DARC) films, which were then reacted with collagen to obtain DARC/Col composite films. The subsequent FT-IR spectra indicated that collagen was immobilized on the DARC matrix via the Schiff base reaction between NH2 in collagen and CHO in DARC backbone. Scanning electron microscopy revealed that DARC/Col exhibited a refined 3D network structure and its porosity and pore size decreased with increasing of collagen concentration. The composite films demonstrated a good equilibrium-swelling ratio, air permeability and water retention properties. The composite films also showed excellent mechanical properties, which was vital for practical application. Finally, the cytotoxicity of the composite film was evaluated using NIH3T3 mice fibroblast cells, the results revealed that DARC/Col composite films have good biocompatibility for use as scaffold material in tissue engineering. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. One-step electrochemical synthesis of graphene/polyaniline composite film and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xiao-Miao; Li, Rui-Mei; Ma, Yan-Wen; Chen, Run-Feng; Shi, Nai-En; Fan, Qu-Li; Huang, Wei [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210046 (China)

    2011-08-09

    This work describes a new one-step large-scale electrochemical synthesis of graphene/polyaniline (PANI) composite films using graphite oxide (GO) and aniline as the starting materials. The size of the film could be controlled by the area of indium tin oxide (ITO). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and ultraviolet-visible absorption spectrum (UV-vis) results demonstrated that the graphene/PANI composite film was successfully synthesized. The obtained graphene/PANI composite film showed large specific area, high conductivity, good biocompatibility, and fast redox properties and had perfect layered and encapsulated structures. Electrochemical experiments indicated that the composite film had high performances and could be widely used in applied electrochemical fields. As a model, horseradish peroxidase (HRP) was entrapped onto the film-modified glassy carbon electrode (GCE) and used to construct a biosensor. The immobilized HRP showed a pair of well-defined redox peaks and high catalytic activity for the reduction of H{sub 2}O{sub 2}. Furthermore, the graphene/PANI composite film could be directly used as the supercapacitor electrode. The supercapacitor showed a high specific capacitance of 640 F g{sup -1} with a retention life of 90% after 1000 charge/discharge cycles. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Spectral selectivity of 3D magnetophotonic crystal film fabricated from single butterfly wing scales

    Science.gov (United States)

    Peng, Wenhong; Zhu, Shenmin; Zhang, Wang; Yang, Qingqing; Zhang, Di; Chen, Zhixin

    2014-05-01

    3D magnetophotonic crystal (3D-MPC) film is an excellent platform for tailoring the magneto-optical response of magnetic materials. However, its fabrication is a great challenge due to the limitation of commonly used artificial synthesis methods. Inspired by the unique structures of biospecies, we hereby manipulate the pristine single wing scales of Morpho didius precisely and successfully fabricate Fe3O4 films with photonic structure. The synthesis strategy involves the fabrication of Fe2O3 film from a single wing scale using an improved sol-gel method followed by a subsequent reduction. The intrinsic hierarchical photonic structures as well as the anisotropic optical properties of the pristine butterfly wing scale have been retained in the obtained Fe2O3 and Fe3O4 films. When investigated under an external magnetic field, a spectral blue shift about 43 nm is observed in the designated orientation of the Fe3O4 film, which is useful for the design and creation of novel magnetic-optical modulator devices. Furthermore, these single scales can be used as building blocks to fabricate designable and more complicated assembled nano systems. This biomimetic technique combined with the variety of structures of butterfly wing scales provides an effective approach to produce magneto-photonic films with desired structure, paving a new way for theoretical research and practical applications.3D magnetophotonic crystal (3D-MPC) film is an excellent platform for tailoring the magneto-optical response of magnetic materials. However, its fabrication is a great challenge due to the limitation of commonly used artificial synthesis methods. Inspired by the unique structures of biospecies, we hereby manipulate the pristine single wing scales of Morpho didius precisely and successfully fabricate Fe3O4 films with photonic structure. The synthesis strategy involves the fabrication of Fe2O3 film from a single wing scale using an improved sol-gel method followed by a subsequent reduction

  4. Compositional and structural changes in TiB{sub 2} films induced by bias, in situ and post-deposition annealing, respectively

    Energy Technology Data Exchange (ETDEWEB)

    Pelleg, Joshua [Department of Materials Engineering, Ben Gurion University of the Negev, 84105, Beer Sheva (Israel)]. E-mail: pelleg@bgumail.bgu.ac.il; Sade, G. [Department of Materials Engineering, Ben Gurion University of the Negev, 84105, Beer Sheva (Israel); Sinder, M. [Department of Materials Engineering, Ben Gurion University of the Negev, 84105, Beer Sheva (Israel); Mogilyanski, D. [Department of Materials Engineering, Ben Gurion University of the Negev, 84105, Beer Sheva (Israel)

    2006-05-31

    Structural changes in TiB{sub 2} films were induced at relatively low temperatures by the application of bias and in situ annealing or by post-deposition heat treatment of samples subjected to bias with simultaneous in situ annealing. In situ annealing by itself evoked only partial crystallization. Application of bias by itself only modified the composition of the as deposited film. A simple model is presented to explain the variation of the composition when RF bias is applied to a cold substrate. The crystallized films had a (0001) texture. A model has been suggested to explain the observed preferred orientation, based on the contribution of surface and strain energies. Both, the surface energy and strain energy are direction dependent. These were evaluated for two film orientations reported in the literature, namely, the (0001) and (101-bar 1)orientations. The preferred orientation of the film is determined by the lowest overall free energy resulting from the competition between the surface energy and the strain energy on different lattice planes. The surface energy is not film thickness dependent while the strain energy is thickness dependent and increases with it. For small film thickness, as in this work, the surface energy term is significant and (0001) orientation with a minimum surface energy is preferred. At large film thicknesses the strain energy becomes dominant and the (101-bar 1) preferred orientation is observed. Under certain experimental conditions strain energy effects may tip the preferred orientation to (101-bar 1). The elastic moduli in the (0001) and (101-bar 1) directions were determined as 435 and 538GPa, respectively.

  5. A dense and strong bonding collagen film for carbon/carbon composites

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Sheng; Li, Hejun, E-mail: lihejun@nwpu.edu.cn; Li, Kezhi; Lu, Jinhua; Zhang, Leilei

    2015-08-30

    Graphical abstract: - Highlights: • Significantly enhancement of biocompatibility on C/C composites by preparing a collagen film. • The dense and continuous collagen film had a strong bonding strength with C/C composites after dehydrathermal treatment (DHT) crosslink. • Numerous oxygen-containing functional groups formed on the surface of C/C composites without matrix damage. - Abstract: A strong bonding collagen film was successfully prepared on carbon/carbon (C/C) composites. The surface conditions of the modified C/C composites were detected by contact angle measurements, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectra. The roughness, optical morphology, bonding strength and biocompatibility of collagen films at different pH values were detected by confocal laser scanning microscope (CLSM), universal test machine and cytology tests in vitro. After a 4-h modification in 30% H{sub 2}O{sub 2} solution at 100 °C, the contact angle on the surface of C/C composites was decreased from 92.3° to 65.3°. Large quantities of hydroxyl, carboxyl and carbonyl functional groups were formed on the surface of the modified C/C composites. Then a dense and continuous collagen film was prepared on the modified C/C substrate. Bonding strength between collagen film and C/C substrate was reached to 8 MPa level when the pH value of this collagen film was 2.5 after the preparing process. With 2-day dehydrathermal treatment (DHT) crosslinking at 105 °C, the bonding strength was increased to 12 MPa level. At last, the results of in vitro cytological test showed that this collagen film made a great improvement on the biocompatibility on C/C composites.

  6. Preparation and Properties of Functional Graphene/Thermoplastic Polyurethane Composite Film

    OpenAIRE

    ZHENG Hui-dong; OU Zhong-xing; ZHENG Yu-ying; XIAO Dong-sheng; CAO Ning-ning

    2016-01-01

    The modified graphene oxide(DD-GO) was reacted by the Didodecyldimethylammonium bromide (DDAB) and graphene oxide,and then reduced via L-ascorbic acid to obtain functional graphene(DD-RGO). Functional graphene (DD-RGO)/thermoplastic polyurethane (TPU) composite films were prepared by solution on the coating machine. The morphology and properties of DD-RGO/TPU composite films were investigated by FTIR, XRD, FE-SEM, oxygen transmission rate tester and high resistance meter. The results show tha...

  7. Surface modification of bioactive glasses and preparation of PDLLA/bioactive glass composite films.

    Science.gov (United States)

    Gao, Yuan; Chang, Jiang

    2009-08-01

    In order to improve the homogeneous dispersion of particles in the polymeric matrix, 45S5, mesoporous 58S, and 58S bioactive glasses were surface modified by esterification reactions with dodecyl alcohol at reflux temperature of 260 degrees C (named as m-45S5, m-mesoporous 58S, and m-58S, respectively). The modified particles showed better hydrophobicity and longer time of suspension in organic matrix. The PDLLA/bioactive glass composite films were fabricated using surface modified bioactive glass particles through solvent casting-evaporation method. Surface morphology, mechanical property, and bioactivity were investigated. The results revealed that the inorganic particle distribution and tensile strength of the composite films with modified bioactive glass particles were significantly improved while great bioactive properties were maintained. Scanning electron microscopy (SEM) observation illustrated that the modified bioactive glass particles were homogeneously dispersed in the PDLLA matrix. The maximum tensile strengths of composite films with modified bioactive glass particles were higher than that of composite films with unmodified bioactive glass particles. The bioactivity of the composite films were evaluated by being soaked in the simulated body fluid (SBF) and the SEM observation of the films suggested that the modified composite films were still bioactive in that they could induce the formation of HAp on its surface and the distribution of HAp was even more homogeneous on the film. The results mentioned above indicated that the surface modification of bioactive glasses with dodecyl alcohol was an effective method to prepare PDLLA/bioactive glass composites with enhanced properties. By studying the comparisons of modification effects among the three types of bioactive glasses, we could get the conclusion that the size and morphology of the inorganic particles would greatly affect the modification effects and the properties of composites.

  8. Electrophoretic deposition of hyaluronic acid and composite films for biomedical applications

    Science.gov (United States)

    Ma, R.; Li, Y.; Zhitomirsky, I.

    2010-06-01

    Hyaluronic acid (HYH) is a natural biopolymer, which has tremendous potential for various biomedical applications. Electrophoretic deposition (EPD) methods have been developed for the fabrication of HYH films and composites. New methods for the immobilization of drugs and proteins have been utilized for the fabrication of organic composites. Electrophoretic deposition enabled the fabrication of organic-inorganic composites containing bioceramics and bioglass in the HYH matrix. It was shown that the deposition yield, microstructure, and composition of the films can be controlled. Potential applications of EPD for the surface modification of biomedical implants and fabrication of biosensors are highlighted.

  9. Isotactic polypropylene carbon nanotube composites -- crystallization and ordering behavior

    Science.gov (United States)

    Georgiev, Georgi; Judith, Robert; Gombos, Erin; McIntyre, Michael; Schoen, Scott; Cebe, Peggy; Mattera, Michael

    2010-03-01

    The field of Polymer Nanocomposites (PNCs) is growing steadily in recent years. We use carbon nanotubes (CNTs) to affect the crystallization behavior of the polymers. Isotactic Polypropylene (iPP) is very widely used and is a good model system to understand the physics of other similar polymers. iPP/CNT PNCs form α, β, and γ crystallographic phases under a variety of crystallization conditions: non-isothermal and isothermal melt crystallization, shear, stress, fiber extrusion, etc. The crystal growth is altered from spherulitic to α-fibrillar upon the nucleation effect of CNTs. We are studying the effect of different temperature treatment schemes and different isothermal crystallization conditions. We found also that the smectic ordering in iPP is improved by the introduction of CNTs. We use Differential Scanning Calorimetry, Wide Angle X-ray scattering, Microscopic Transmission Ellipsometry and Avrami analysis. Research supported by: Assumption College Faculty Development Grant, funding for students' stipends, instrumentation and supplies, the NSF Polymers Program of the DMR, grant (DMR-0602473) and NASA grant (NAG8-1167).

  10. Development and Characterization of Biodegradable Composite Films Based on Gelatin Derived from Beef, Pork and Fish Sources

    Directory of Open Access Journals (Sweden)

    Zainal A. Nur Hanani

    2013-01-01

    Full Text Available The objectives of this study were to develop composite films using various gelatin sources with corn oil (CO incorporation (55.18% and to investigate the mechanical and physical properties of these films as potential packaging films. There were increases (p < 0.05 in the tensile strength (TS and puncture strength (PS of films when the concentration of gelatin increased. The mechanical properties of these films were also improved when compared with films produced without CO. Conversely, the water barrier properties of composite films decreased (p < 0.05 when the concentration of gelatin in composite films increased. Comparing with pure gelatin films, water and oxygen barrier properties of gelatin films decreased when manufactured with the inclusion of CO.

  11. Properties of composite film based on bigeye snapper surimi protein and lipids

    Directory of Open Access Journals (Sweden)

    Thummanoon Prodpran

    2005-12-01

    Full Text Available Lipids were incorporated into bigeye snapper surimi protein films through emulsification using Tween-20 as a surfactant to form protein/lipid composite films. The effects of lipid types (palm oil, butter or shortening and concentrations (0-100% glycerol substitution on film properties were investigated. Additionof lipids up to 75% glycerol substitution resulted in the improved water vapor barrier, lowered tensile strength (TS and increased elongation at break (EAB of the composite film (P<0.05. However, an increase in TS was observed with increasing lipid concentration, plausibly caused by increasing protein aggregation in film matrix. Transparency of films was decreased with increasing lipid concentrations used (P<0.05, especially for those added with solid lipids. Generally, the mechanical properties and water resistance of surimi protein films incorporated with palm oil were superior to those modified with butter or shortening. An increase in Tween-20, nonionic surfactant, might be associated with the decrease in non-disulfide covalent cross-links in the film. Scanning electron microscopic study revealed that dispersion of palm oil in the film was more uniform than that of butter and shortening. This might contribute to the varying properties of resulting films.

  12. Effect of preheating on the film thickness of contemporary composite restorative materials

    OpenAIRE

    Dimitrios Dionysopoulos; Kosmas Tolidis; Paris Gerasimou; Eugenia Koliniotou-Koumpia

    2014-01-01

    Background/purpose: Recently, the placement of composite materials at an elevated temperature has been proposed in order to increase their flow for better adaptation in cavity walls. The aim of this in vitro study was to evaluate the effect of preheating on the film thickness of a variety of commercially available conventional composites and to compare them with those obtained from a variety of flowable composites at room temperature. Materials and methods: The composites were three nanohy...

  13. Poly-crystalline thin-film by aluminum induced crystallization on aluminum nitride substrate

    Science.gov (United States)

    Bhopal, Muhammad Fahad; Lee, Doo Won; Lee, Soo Hong

    2016-09-01

    Thin-film polycrystalline silicon ( pc-Si) on foreign (non-silicon) substrates has been researched by various research groups for the production of photovoltaic cells. High quality pc-Si deposition on foreign substrates with superior optical properties is considered to be the main hurdle in cell fabrication. Metal induced crystallization (MIC) is one of the renowned techniques used to produce this quality of material. In the current study, an aluminum induced crystallization (AIC) method was adopted to produce pc-Si thin-film on aluminum nitride (AlN) substrate by a seed layer approach. Aluminum and a-Si layer were deposited using an e-beam evaporator. Various annealing conditions were used in order to investigate the AIC grown pc-Si seed layers for process optimization. The effect of thermal annealing on grain size, defects preferentially crystallographic orientation of the grains were analyzed. Surface morphology was studied using an optical microscope. Poly-silicon film with a crystallinity fraction between 95-100% and an FWHM between 5-6 cm-1 is achievable at low temperatures and for short time intervals. A grain size of about 10 micron can be obtained at a low deposition rate on an AIN substrate. Similarly, Focused ion beam (FIB) also showed that at 425 °C sample B and at 400 °C sample A were fully crystallized. The crystalline quality of pc-Si was evaluated using μ-Raman spectroscopy as a function of annealed conditions and Grazing incidence X-ray diffraction (GIXRD) was used to determine the phase direction of the pc-Si layer. The current study implicates that a poly-silicon layer with good crystallographic orientation and crystallinity fraction is achievable on AIN substrate at low temperatures and short time frames.

  14. Surface patterns on single-crystal films under uniaxial stress: Experimental evidence for the Grinfeld instability

    Science.gov (United States)

    Berréhar, J.; Caroli, C.; Lapersonne-Meyer, C.; Schott, M.

    1992-11-01

    We study the stress relaxation in single-crystal films of polymerized polydiacetylene, in epitaxy with their monomer substrate. Polymerization induces a uniaxial stress. Two types of surface patterns are observed and studied by atomic force microscopy: films thicker than 175 nm exhibit quasiperiodic cracks perpendicular to the polymer chains; thinner ones exhibit regular wrinkles with the same orientation. The wrinkle surface deformation is stress relaxing and plastic. We show that all experimental results, in particular, the order of magnitude of the pattern spacings, are compatible with the following interpretation: as polymerization proceeds, the uniaxial stress generates a Grinfeld instability (Dok. Akad. Nauk SSSR 290, 1358 (1986) [Sov. Phys. Dokl. 31, 831 (1986)]) fed by surface diffusion. The crack pattern is a secondary instability, initiated at the sites of stress concentration provided by the wrinkles.

  15. Poly-Si films with low aluminum dopant containing by aluminum-induced crystallization

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Typically, highly p-doped (2×10 18 cm -3 ) poly-Si films fabricated by the aluminum induced layer exchange (ALILE) process are not suitable for solar cell absorber layers. In this paper, the fabrication of high-quality, continuous polycrystalline silicon (poly-Si) films with lower doping concentrations (2×10 16 cm -3 ) using aluminum-induced crystallization (AIC) is reported. Secondary-ion-mass spectroscopy (SIMS) results showed that annealing at different temperature profiles leads to a variety of Al concentrations. Hall Effect measurements revealed that Al dopant concentration depends on the annealing temperature and temperature profile. Raman spectral analysis indicated that samples prepared via AIC contain some regions with small grains.

  16. Non-classical crystallization of silicon thin films during hot wire chemical vapor deposition

    Science.gov (United States)

    Jung, Jae-Soo; Lee, Sang-Hoon; Kim, Da-Seul; Kim, Kun-Su; Park, Soon-Won; Hwang, Nong-Moon

    2017-01-01

    The deposition behavior of silicon films by hot wire chemical vapor deposition (HWCVD) was approached by non-classical crystallization, where the building block of deposition is a nanoparticle generated in the gas phase of the reactor. The puzzling phenomenon of the formation of an amorphous incubation layer on glass could be explained by the liquid-like property of small charged nanoparticles (CNPs), which are generated in the initial stage of the HWCVD process. Using the liquid-like property of small CNPs, homo-epitaxial growth as thick as 150 nm could be successfully grown on a silicon wafer at 600 °C under the processing condition where CNPs as small as possible could be supplied steadily by a cyclic process which periodically resets the process. The size of CNPs turned out to be an important parameter in the microstructure evolution of thin films.

  17. Thin film pc-Si by aluminium induced crystallization on metallic substrate

    Directory of Open Access Journals (Sweden)

    Cayron C.

    2013-04-01

    Full Text Available Thin film polycrystalline silicon (pc-Si on flexible metallic substrates is promising for low cost production of photovoltaic solar cells. One of the attractive methods to produce pc-Si solar cells consists in thickening a large-grained seed layer by epitaxy. In this work, the deposited seed layer is made by aluminium induced crystallization (AIC of an amorphous silicon (a-Si thin film on metallic substrates (Ni/Fe alloy initially coated with a tantalum nitride (TaN conductive diffusion barrier layer. Effect of the thermal budget on the AIC grown pc-Si seed layer was investigated in order to optimize the process (i.e. the quality of the pc-Si thin film. Structural and optical characterizations were carried out using optical microscopy, μ-Raman and Electron Backscatter Diffraction (EBSD. At optimal thermal annealing conditions, the continuous AIC grown pc-Si thin film showed an average grain size around 15 μm. The grains were preferably (001 oriented which is favorable for its epitaxial thickening. This work proves the feasibility of the AIC method to grow large grains pc-Si seed layer on TaN coated metal substrates. These results are, in terms of grains size, the finest obtained by AIC on metallic substrates.

  18. Comparison between AlN thin films with different crystal orientations for MEMS applications

    Science.gov (United States)

    Ababneh, A.; Marchand, G.; Seidel, H.; Hernando, J.; Sánchez-Rojas, J. L.; Sökmen, Ü.; Peiner, E.; Schmid, U.

    2009-05-01

    Aluminium nitride (AlN) reactively sputter deposited from an aluminium target is an interesting compound material due to its CMOS compatible fabrication process and its piezoelectric properties. The crystal structure obtained during sputtering is a very importance criterion to obtain a good piezoelectric performance. To demonstrate this, we focused our investigations on two types of films. The first type shows a good c- axis orientation with round grain geometry. The second type is (101) oriented having a triangular grain shape. For measuring the out-of-plane displacements for dij determination, a MSV 400 Polytec scanning laser Doppler vibrometer was used. To obtain the piezoelectric constants d33 and d31 a fitting procedure between experimental and theoretical predicted results is used. Effective values for d33 and d31 in c-axis oriented films are about 3.0 pm/V and -1.0 pm/V, respectively. By contrast, films with (101) orientation show a lower effective longitudinal piezoelectric coefficients, consistent with this different orientation. Finally, both types of AlN layers were deposited on 640 μm long micro-cantilevers. The average displacement of the first mode on the vertical axis was about 12 nm for the film with good c -axis orientation and 0.3 nm for that with (101)- orientation when applying the same excitation.

  19. Synthesis and characterization of large-grain solid-phase crystallized polycrystalline silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avishek, E-mail: avishek.kumar@nus.edu.sg, E-mail: dalapatig@imre.a-star.edu.sg [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Block E3A, #06-01, Singapore 117574 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Law, Felix; Widenborg, Per I. [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Block E3A, #06-01, Singapore 117574 (Singapore); Dalapati, Goutam K., E-mail: avishek.kumar@nus.edu.sg, E-mail: dalapatig@imre.a-star.edu.sg; Subramanian, Gomathy S.; Tan, Hui R. [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Aberle, Armin G. [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Block E3A, #06-01, Singapore 117574 and Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore)

    2014-11-01

    n-type polycrystalline silicon (poly-Si) films with very large grains, exceeding 30 μm in width, and with high Hall mobility of about 71.5 cm{sup 2}/V s are successfully prepared by the solid-phase crystallization technique on glass through the control of the PH{sub 3} (2% in H{sub 2})/SiH{sub 4} gas flow ratio. The effect of this gas flow ratio on the electronic and structural quality of the n-type poly-Si thin film is systematically investigated using Hall effect measurements, Raman microscopy, and electron backscatter diffraction (EBSD), respectively. The poly-Si grains are found to be randomly oriented, whereby the average area weighted grain size is found to increase from 4.3 to 18 μm with increase of the PH{sub 3} (2% in H{sub 2})/SiH{sub 4} gas flow ratio. The stress in the poly-Si thin films is found to increase above 900 MPa when the PH{sub 3} (2% in H{sub 2})/SiH{sub 4} gas flow ratio is increased from 0.025 to 0.45. Finally, high-resolution transmission electron microscopy, high angle annular dark field-scanning tunneling microscopy, and EBSD are used to identify the defects and dislocations caused by the stress in the fabricated poly-Si films.

  20. Melting of a nonequilibrium vortex crystal in a fluid film with polymers : elastic versus fluid turbulence

    CERN Document Server

    Gupta, Anupam

    2016-01-01

    We perform a direct numerical simulation (DNS) of the forced, incompressible two-dimensional Navier-Stokes equation coupled with the FENE-P equations for the polymer-conformation tensor. The forcing is such that, without polymers and at low Reynolds numbers $Re$, the film attains a steady state that is a square lattice of vortices and anti-vortices. We find that, as we increase the Weissenberg number ${\\mathcal Wi}$, this lattice undergoes a series of nonequilibrium phase transitions, first to spatially distorted, but temporally steady, crystals and then to a sequence of crystals that oscillate in time, periodically, at low ${\\mathcal Wi}$, and quasiperiodically, for slightly larger ${\\mathcal Wi}$. Finally, the system becomes disordered and displays spatiotemporal chaos and elastic turbulence. We then obtain the nonequilibrium phase diagram for this system, in the ${\\mathcal Wi} - Re$ plane, and show that (a) the boundary between the crystalline and turbulent phases has a complicated, fractal-type character ...

  1. Photonic-crystal switch divider based on Ge2Sb2Te5 thin films.

    Science.gov (United States)

    Ma, Beijiao; Zhang, Peiqing; Wang, Hui; Zhang, Tengyu; Zeng, Jianghui; Zhang, Qian; Wang, Guoxiang; Xu, Peipeng; Zhang, Wei; Dai, Shixun

    2016-11-10

    A three-port phase-change photonic-crystal switch divider based on Ge2Sb2Te5 chalcogenide thin film was proposed. The chalcogenide material used was determined to have a high refractive index and fast phase-change speed by using laser radiation. The structure with a T-junction cavity was used to achieve three switch functions: switching "ON" in only one output port, switching "OFF" in both output ports, and dividing signals into two output ports. The transmission properties of the designed device at 2.0 μm were studied by the finite difference time domain method, which showed that the switch divider can achieve very high switching efficiency by optimizing T-junction cavity parameters. The scaling laws of photonic crystals revealed that the operating wavelength of the designed structure can be easily extended to another wavelength in the midinfrared region.

  2. Ferrimagnetic ordering of single crystal Fe1-xGax thin films

    Energy Technology Data Exchange (ETDEWEB)

    McClure, A.; Arenholz, E.; Idzerda, Y. U.

    2009-10-19

    Molecular beam epitaxy was used to deposit body centered cubic single crystal Fe{sub 1-x}Ga{sub x} thin films on MgO(001) and ZnSe/GaAs(001) substrates well beyond the bulk stability concentration of about 28%. The crystal quality of the substrate surface and each deposited layer was monitored in situ by reflection high energy electron diffraction. The magnetization of the samples as a function of Ga is found to decrease more rapidly than a simple dilution effect, and element-specific x-ray magnetic circular dichroism ascribes this trend to a decrease in the Fe moment and an induced moment in the Ga that is antialigned to the Fe moment.

  3. Dual-functional sensor based on switchable plasmonic structure of VO2 nano-crystal films and Ag nanoparticles.

    Science.gov (United States)

    Yi, Mingfang; Lu, Changgui; Gong, Yan; Qi, Zhengqing; Cui, Yiping

    2014-12-01

    Utilizing the insulator-metal phase transition of vanadium dioxide (VO2) crystal films, we develop a dual-functional sensor based on the coupling between VO2 nano-crystal films and Ag nanoparticles, which can probe fluorescence or Raman signals on the same substrate and it is switchable by changing temperature. At room temperature, the VO2 crystal films is insulator phase and the fluorescence signals of probe molecules (R6G) is detectable (Raman is in "off"). At high temperature (such as 85 °C), the VO2 crystal films become metallic phase. Ag nanoparticles interact with the metal phase of VO2 crystal films to produce stronger localized electric field. The stronger electric field can excite the Raman signals of probe molecules (R6G) and the coupled structure can also emit the Raman signals out efficiently (Raman is in "on"). The switchable probe of fluorescence and Raman signals would have potential applications in active photoelectric components, such as intelligent switch and multifunctional active sensor etc.

  4. Research on Mechanical Behaviors of Micro-crystal Muscovite/UHMWPE Composites to Impact Loading

    Directory of Open Access Journals (Sweden)

    Hu Huarong

    2016-01-01

    Full Text Available UHMWPE composites were prepared by hot pressing process with micro-crystal muscovite as reinforced particulates. The mechanical behaviors of composites to impact loading was evaluated by split Hopkinson bar. The results demonstrated that dynamic yield stress and failure stress of UHMWPE composites were gradually increased when the filling amount was less than 20%; when the filling content of muscovite was around 15%, the energy absorption efficiency of the composite reaches maximum value. It was also found that when strain rate within 3200/s, the dynamic yield stress, failure stress and energy absorption efficiency of UHMWPE composites increased with the increase of strain rate and display strain rate enhancement effect.

  5. Thin films of metal oxides on metal single crystals: Structure and growth by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Galloway, Heather Claire [Univ. of California, Berkeley, CA (United States)

    1995-12-01

    Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(III) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing, the structures of different oxides.

  6. Preparation of zirconium phenylphosphonate films with different crystallite orientations on polystyrene substrates by in situ hydrothermal crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Lei Xiaodong; Wang Lei; Cui Zhaohui; Xu Sailong; Zhang Fazhi, E-mail: zhangfz@mail.buct.edu.c

    2011-03-31

    Zirconium phenylphosphonate (ZrPP) films with different crystallite orientations have been fabricated on unmodified and surface-sulfonated polystyrene (PS) substrates by an in situ hydrothermal crystallization method. On the unmodified PS substrate, a monolayer film with the hexagonal ab planes of the ZrPP crystallites parallel to the PS can be obtained by restricting the crystallization time. After a longer crystallization time, the ZrPP films adopt a bilayer arrangement, with the ab planes of the ZrPP crystallites in the lower layer being parallel to the substrate, and the ab planes of the ZrPP crystallites in the upper layer being perpendicular to the substrate. On the surface-sulfonated PS, however, the ZrPP crystallites form a monolayer film with their ab planes perpendicular to the substrate irrespective of the crystallization time. We suggest that the different interactions between the ZrPP crystallites and the two substrates, namely the {pi}-{pi} interactions between the phenyl groups in the ZrPP surface and those in the unmodified PS substrate, and the coordinate interactions between the lone pairs of electrons on oxygen atoms in the sulfonate groups on the sulfonated PS and vacant coordination sites on Zr atoms on the edges of ZrPP crystallites, are responsible for the different morphologies of the monolayer films on the unmodified and sulfonated substrates. Two distinct growth mechanisms are proposed which can satisfactorily account for the different crystallite orientations in the two ZrPP films.

  7. THE EFFECT OF CLAY DISPERSION ON THE CRYSTALLIZATION AND MORPHOLOGY OF POLYPROPYLENE/CLAY COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Qin Zhang; Xiao-lin Gao; Ke Wang; Qiang Fu

    2004-01-01

    PP/clay composites with different dispersions, namely, exfoliated dispersion, intercalated dispersion and agglomerates and panicle-like dispersion, were prepared by direct melt intercalation or compounding. The effect of clay dispersion on the crystallization and morphology of PP was investigated via PLM, SAXS and DSC. Experimental results show that exfoliated clay layers are much more efficient than intercalated clay and agglomerates of clay in serving as nucleation agent due to the nano-scale dispersion of clay, resulting in a dramatic decrease in crystal size (lamellar thickness and spherulites) and an increase of crystallization temperature and crystallization rate. On the other hand, a decrease of melting temperature and crystallinity was also observed in PP/clay composites with exfoliated dispersion, due to the strong interaction between PP and clay. Compared with exfoliated clay layers, the intercalated clay layers have a less important effect on the crystallization and crystal morphology. No effect is seen for samples with agglomerates and panicle-like dispersion, in regard to melting temperature, crystallization temperature, crystal thickness and crystallinity.

  8. Effects of crystallization fractions on mechanical properties of Zr-based metallic glass matrix composites

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Zr41Ti14Cu12.5Ni10Be22.5 (at.%) bulk metallic glass composites with various crystallization fractions were prepared by pretreating the bulk metallic glassy samples with pulsing current, and then by isothermal annealing at near initial crystallization temperature for different periods of time. The precipitations and crystallization fractions were studied by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), and their effects on mechanical properties of the composite were studied by microhardness, uniaxial compression test and scanning electron microscopy (SEM). The experimental results show that the primary precipitate is quasicrystalline phase and other metastable phases including Be2Zr, Zr2Cu and FCC would precipitate subsequently. In the initial crystallization process, in which the crystallization fraction increases from 0 to 8.2%, both fracture strength and plastic strain increase, with the maximum plastic strain up to 6.4%. When the crystallization fraction is larger than 8.2%, the fracture strength and the plastic strain decrease sharply. Furthermore, the alloy with low crystallization fraction is fractured by shearing, while for high crystallization fraction it is fractured by splitting and cleavage. The results show that the mechanical properties of the glassy alloy could be optimized by controlling the processing parameters.

  9. Determination of the area density and composition of alloy film using dual alpha particle energy loss

    Science.gov (United States)

    Ma, Xiaojun; Li, Bo; Gao, Dangzhong; Xu, Jiayun; Tang, Yongjian

    2017-02-01

    A novel method based on dual α-particles energy loss (DAEL) is proposed for measuring the area density and composition of binary alloy films. In order to obtain a dual-energy α-particles source, an ingenious design that utilizes the transmitted α-particles traveling the thin film as a new α-particles source is presented. Using the DAEL technique, the area density and composition of Au/Cu film are determined accurately with an uncertainty of better than 10%. Finally, some measures for improving the combined uncertainty are discussed.

  10. Thin Film Heat Flux Sensor Development for Ceramic Matrix Composite (CMC) Systems

    Science.gov (United States)

    Wrbanek, John D.; Fralick, Gustave C.; Hunter, Gary W.; Zhu, Dongming; Laster, Kimala L.; Gonzalez, Jose M.; Gregory, Otto J.

    2010-01-01

    The NASA Glenn Research Center (GRC) has an on-going effort for developing high temperature thin film sensors for advanced turbine engine components. Stable, high temperature thin film ceramic thermocouples have been demonstrated in the lab, and novel methods of fabricating sensors have been developed. To fabricate thin film heat flux sensors for Ceramic Matrix Composite (CMC) systems, the rough and porous nature of the CMC system posed a significant challenge for patterning the fine features required. The status of the effort to develop thin film heat flux sensors specifically for use on silicon carbide (SiC) CMC systems with these new technologies is described.

  11. Optical Properties of Semiconductor-Metal Composite Thin Films in the Infrared Region

    Science.gov (United States)

    Nagendra, C. L.; Lamb, James L.

    1993-01-01

    Germanium:Silver (Ge:Ag) composite thin films having different concentrations of Ag, ranging from 7% to 40% have been prepared by dc co-sputtering of Ge an Ag and the films' surface morphology and optical properties have been characterized using transmission electron microscopy (TEM) and infrared spectrophotometry. It is seen that while the films containing lower concentrations of Ag have island-like morphology (i.e. Ag particles distributed in a Ge matrix), the higher metallic concentration films tend to have symmetric distribution of Ag and Ge.

  12. PREPARATION AND CORROSION RESISTANCE OF NiP/TiO2 COMPOSITE FILM ON CARBON STEEL IN SULFURIC ACID SOLUTION

    Institute of Scientific and Technical Information of China (English)

    L.Z. Song; S.Z. Song; J. Zhao

    2006-01-01

    A NiP/TiO2 composite film on carbon steel was prepared by electroless plating and sol-gel composite process. An artificial neural network was applied to optimize the prepared condition of the composite film. Corrosion behavior of the NiP/TiO2 composite film was investigated by polarization resistance measurement, anode polarization, ESEM (environmental scanning electron microscopy)and EIS (electrochemical impedance spectroscopy) measurements. Results showed that the NiP/TiO2 composite film has a good corrosion resistance in 0.5mol/L H2SO4 solution. The element valence of the composite film was characterized by XPS (X-ray photoelectron spectroscopy) spectrum, and an anticorrosion mechanism of the composite film was discussed.

  13. Composition, Constitution and Phase Transformation Behavior in Thin-Film and Bulk Ti-Ni-Y

    Science.gov (United States)

    König, D.; Frowein, P.; Wieczorek, A.; Frenzel, J.; Hamann, S.; Eggeler, G.; Ludwig, A.

    2017-01-01

    Advanced engineering applications require new and improved shape memory alloys in bulk and thin-film form. While many Ti-Ni-based systems have been studied so far, the Ti-Ni-Y materials system was not studied in detail concerning its bulk and thin-film shape memory properties. For this reason, a Ti-Ni-Y thin-film materials library focussing on compositions close to Ni50Ti50 was fabricated by combinatorial magnetron sputtering. This library was characterized by high-throughput methods and the compositional range where phase transformations occur was identified. Ti-Ni-Y thin films exhibit a very narrow hysteresis width ∆T and allow to precisely adjust ∆T. Based on the promising results of Ti-Ni-Y thin films, which can be directly applied in microsystems, bulk alloys were fabricated in order to explore how thin-film and bulk properties of different Ti-Ni-Y compositions correlate. It turned out that Ti-Ni-Y bulk materials show different phase transformation properties compared to thin films, most importantly higher ∆T. The differences between thin-film and bulk material are discussed.

  14. Development and characterization of carrageenan/grapefruit seed extract composite films for active packaging.

    Science.gov (United States)

    Kanmani, Paulraj; Rhim, Jong-Whan

    2014-07-01

    Carrageenan-based antimicrobial films were developed by incorporation of grape fruit seed extract (GSE) at different concentration into the polymer using a solvent casing method and their physical, mechanical, and antimicrobial properties were examined. The carrageenan/GSE composite films appeared yellowish tint due to the polyphenolic compounds in the GSE. SEM analysis showed rough surface with sponge like structures on the cross section of the films. FT-IR results indicated at GSE had good compatibility with carrageenan. The amorphous structure of polymer films was not changed by the incorporation of GSE. But, the addition of GSE increased moisture content, water vapor permeability, and surface hydrophilicity of the films. The tensile strength and elastic modulus decreased with increasing content of GSE, however, the elongation at break increased significantly up to 6.6μg/mL of GSE then decreased thereafter. Thermal stability of the films was not influenced by GSE incorporation. The carrageenan/GSE composite films exhibited great antibacterial activity against food borne pathogens. These results suggest that the carrageenan-based composite films have a high potential for being used as an antimicrobial or active food packaging applications.

  15. Composite Films from Sodium Alginate and High Methoxyl Pectin - Physicochemical Properties and Biodegradation in Soil

    Directory of Open Access Journals (Sweden)

    Ayten O. Solak

    2014-12-01

    Full Text Available The increased public attention on the waste pollution and the awareness of the hard environmental problems is the reason for the need of new materials which are susceptible to degradation in nature for a short period of time. The biopolymer films and coatings based on renewable natural sources are suitable for obtaining of biodegradable packaging. The newly developed composite films based on sodium alginate and apple high methoxyl pectin were studied for total soluble matter, swelling in water, water vapors transmission rate and biodegradation in soil. The analysis of their behavior in water medium showed a considerably higher rate and degree of dissolution of the pectin monocomponent film compared to the composite and alginate films. The composite alginate-pectin films showed lower water vapors transmission rate even under extreme conditions (38ºC, RH 90 % compared to the monocomponent films. All investigated films degraded in soil up to 80 days. The good barrier properties to water vapors and the complete biodegradation in soil make the films based on sodium alginate and high methoxyl pectin potential ecological materials for packing and coating of foods and pharmaceutical products.

  16. Composition, Constitution and Phase Transformation Behavior in Thin-Film and Bulk Ti-Ni-Y

    Science.gov (United States)

    König, D.; Frowein, P.; Wieczorek, A.; Frenzel, J.; Hamann, S.; Eggeler, G.; Ludwig, A.

    2017-03-01

    Advanced engineering applications require new and improved shape memory alloys in bulk and thin-film form. While many Ti-Ni-based systems have been studied so far, the Ti-Ni-Y materials system was not studied in detail concerning its bulk and thin-film shape memory properties. For this reason, a Ti-Ni-Y thin-film materials library focussing on compositions close to Ni50Ti50 was fabricated by combinatorial magnetron sputtering. This library was characterized by high-throughput methods and the compositional range where phase transformations occur was identified. Ti-Ni-Y thin films exhibit a very narrow hysteresis width ∆ T and allow to precisely adjust ∆ T. Based on the promising results of Ti-Ni-Y thin films, which can be directly applied in microsystems, bulk alloys were fabricated in order to explore how thin-film and bulk properties of different Ti-Ni-Y compositions correlate. It turned out that Ti-Ni-Y bulk materials show different phase transformation properties compared to thin films, most importantly higher ∆ T. The differences between thin-film and bulk material are discussed.

  17. Mechanical, tribological and corrosion performance of WBN composite films deposited by reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Lihua; Zhao, Hongjian; Xu, Junhua, E-mail: jhxu@just.edu.cn

    2014-10-01

    Highlights: • WBN composite films were deposited by reactive magnetron sputtering. • The WBN film which exhibited the highest hardness had best wear resistance at room and elevated temperature. • The corrosion resistance of the substrate which coated with W{sub 2}N films or WBN films was superior to the uncoated substrate. • The corrosion resistance of the substrate which coated with W{sub 2}N films was improved slightly by doping some boron content and the corrosion mechanism was discussed in the view of structure. - Abstract: WBN composite films with various boron contents ranging from 25.1 at.% to 46.5 at.% were deposited by a multi-target magnetron sputtering system. The microstructure, mechanical, tribological and corrosion behavior of films were studied using XRD, SEM, FTIR, HRTEM, nano-indentation, Ball-on-disc dry sliding wear tester, Bruker 3D Profiler and compared to W{sub 2}N. All the films exhibited face-centred cubic (fcc) structure W{sub 2}N; bcc α-W phases appeared as the B content was 25.1 at.% and amorphous BN appeared as the B content was 31.9 at.%. The hardness and compressive stress of WBN films first increased and then decreased with increasing the B content. As the B content was 38.1 at.%, they reached the maximum values of 36.1 GPa and 2.6 GPa, respectively. The best wear resistance at room and elevated temperature was found for the film which was shown to exhibit the highest hardness and compressive stress. The corrosion resistance of the substrate which coated with W{sub 2}N films or WBN films was superior to the uncoated substrate. The corrosion resistance of the substrate which coated with W{sub 2}N films was improved slightly by doping some boron content.

  18. Oscillations of composition near the external surface of Y-Ba-Cu-O thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bakunin, O. M.; Klotsman, S. M.; Matveev, S. A.; Stepanov, K. A.

    1989-07-03

    An Auger electron spectroscopy study has been made of the depth profiles of films of Y-Ba-Cu-O compounds. The films were produced by electron beam and ion plasma sputtering onto various substrate types. The specimens were annealed in air at temperatures ranging between 450 and 900 /degree/C. The effective diffusion coefficients for the film and substrate constituents have been estimated. The depth profiles of films annealed at 600 /degree/C reveal composition oscillations in the region adjacent to the surface. These composition oscillations are assumed to arise from the phase transformations that occur at 600 /degree/C in films of the Y-Ba-Cu-O system.

  19. Composition, XRD and morphology study of laser prepared LiNbO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Jelinek, M.; Remsa, J.; Kocourek, T. [Institute of Physics ASCR v.v.i., Prague 8 (Czech Republic); Czech Technical University in Prague, Faculty of Biomedical Engineering, Sitna, Kladno (Czech Republic); Havranek, V. [Nuclear Physics Institute ASCR, Rez near Prague (Czech Republic); Vincze, A.; Bruncko, J. [International Laser Centre, Bratislava 4 (Slovakia); Studnicka, V. [Institute of Physics ASCR v.v.i., Prague 8 (Czech Republic); Rubesova, K. [Institute of Chemical Technology, Prague 6 (Czech Republic)

    2013-03-15

    LiNbO{sub 3} films were deposited by PLD from LiNbO{sub 3} crystalline or from three different stoichiometric or Li-enriched LiNbO{sub 3} targets. Polycrystalline films were prepared on SiO{sub 2}/Si or sapphire substrates at temperatures T{sub S} {proportional_to}650-750 C. Main attention was paid to the influence of targets preparation and the deposition conditions on films composition, morphology and crystallinity. The thin-film morphology was determined by SEM microscopy. The composition was measured by SIMS, RBS, PIXE and PIGE methods. Highly oriented, smooth and stoichiometric LiNbO{sub 3} films were synthesized. (orig.)

  20. Layer-by-layer assembly and UV photoreduction of graphene-polyoxometalate composite films for electronics.

    Science.gov (United States)

    Li, Haolong; Pang, Shuping; Wu, Si; Feng, Xinliang; Müllen, Klaus; Bubeck, Christoph

    2011-06-22

    Graphene oxide (GO) nanosheets and polyoxometalate clusters, H(3)PW(12)O(40) (PW), were co-assembled into multilayer films via electrostatic layer-by-layer assembly. Under UV irradiation, a photoreduction reaction took place in the films which converted GO to reduced GO (rGO) due to the photocatalytic activity of PW clusters. By this means, uniform and large-area composite films based on rGO were fabricated with precisely controlled thickness on various substrates such as quartz, silicon, and plastic supports. We further fabricated field effect transistors based on the composite films, which exhibited typical ambipolar features and good transport properties for both holes and electrons. The on/off ratios and the charge carrier mobilities of the transistors depend on the number of deposited layers and can be controlled easily. Furthermore, we used photomasks to produce conductive patterns of rGO domains on the films, which served as efficient microelectrodes for photodetector devices.