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Sample records for 3-glycidoxypropyltrimethoxysilane films studied

  1. Grafting of organosilane derived from 3-glycidoxypropyltrimethoxysilane and thiourea onto magnesium phyllosilicate by sol-gel process and investigation of metal adsorption properties

    SciTech Connect

    Dey, R.K.; Oliveira, Andrea S.; Patnaik, Tanushree; Singh, V.K.; Tiwary, D.; Airoldi, Claudio

    2009-08-15

    A layered inorganic-organic magnesium silicate (Mg-GTPS-TU) has been successfully synthesized by using sol-gel based precursor under mild temperature conditions and a new silylaing agent (GTPS-TU) derived from 3-glycidoxypropyltrimethoxysilane (GTPS) and thiourea (TU) as the silicon source. The hybrid material was characterized through elemental analysis, infrared spectroscopy, X-ray diffractometry, thermogravimetry, and carbon and silicon solid-state nuclear magnetic resonance spectroscopy. The result confirmed the attachment of organic functionality to the inorganic silicon network. The inter-lamellar distance for the hybrid material was found to be 18.8 A. Metal adsorption characteristics follows Cr(III) >Mn(II)>Zn(II) with more affinity towards Cr(III) in dilute aqueous solution. Evaluation of thermodynamic parameters DELTAH and DELTAS for Cr(III) were found to be 25.44 J mol{sup -1} and 79.9 J mol{sup -1} K{sup -1}, respectively, indicating adsorption process to be endothermic in nature. The negative value of DELTAG indicated the feasibility and spontaneity of ongoing adsorption process at relatively higher temperature. The presence of multiple coordination sites in the attached organic functionality expresses the potentiality of the hybrid material containing new silylating agent for heavy cation removal from eco-system. - Abstract: We report the synthesis and adsorption properties of a layered inorganic-organic magnesium silicate (Mg-GTPS-TU) derived from a new silylaing agent from 3-glycidoxypropyltrimethoxysilane (GTPS) and thiourea (TU) as the silicon source. Display Omitted

  2. Grafting of organosilane derived from 3-glycidoxypropyltrimethoxysilane and thiourea onto magnesium phyllosilicate by sol-gel process and investigation of metal adsorption properties

    NASA Astrophysics Data System (ADS)

    Dey, R. K.; Oliveira, Andrea S.; Patnaik, Tanushree; Singh, V. K.; Tiwary, D.; Airoldi, Claudio

    2009-08-01

    A layered inorganic-organic magnesium silicate (Mg-GTPS-TU) has been successfully synthesized by using sol-gel based precursor under mild temperature conditions and a new silylaing agent (GTPS-TU) derived from 3-glycidoxypropyltrimethoxysilane (GTPS) and thiourea (TU) as the silicon source. The hybrid material was characterized through elemental analysis, infrared spectroscopy, X-ray diffractometry, thermogravimetry, and carbon and silicon solid-state nuclear magnetic resonance spectroscopy. The result confirmed the attachment of organic functionality to the inorganic silicon network. The inter-lamellar distance for the hybrid material was found to be 18.8 Å. Metal adsorption characteristics follows Cr(III) >Mn(II)>Zn(II) with more affinity towards Cr(III) in dilute aqueous solution. Evaluation of thermodynamic parameters ΔH and ΔS for Cr(III) were found to be 25.44 J mol -1 and 79.9 J mol -1 K -1, respectively, indicating adsorption process to be endothermic in nature. The negative value of Δ G indicated the feasibility and spontaneity of ongoing adsorption process at relatively higher temperature. The presence of multiple coordination sites in the attached organic functionality expresses the potentiality of the hybrid material containing new silylating agent for heavy cation removal from eco-system.

  3. Contemporary Films' Mini Course on Film Study.

    ERIC Educational Resources Information Center

    Schillaci, Peter

    This minicourse on film study can be a unit in English, in arts, or in the humanities. It can help to launch a film study course or complement an introduction to theater. Whatever form it takes, it helps to build a bridge to the student's media environment. Part one, the language of images, utilizes four films which demonstrate the basic elements…

  4. Film Study in Higher Education.

    ERIC Educational Resources Information Center

    Stewart, David C., Ed.

    This resource book on the place of film study today is designed to assist in the planning of college courses in the history, criticism, and appreciation of motion pictures. Representative course descriptions and appraisals are given by (1) Jack C. Ellis, who describes a two-part course in film aesthetics and types of films, (2) Edward Fischer, who…

  5. Center for thin film studies

    NASA Astrophysics Data System (ADS)

    Shannon, Robert P.; Gibson, Ursula J.

    1987-11-01

    This report covers the first year of operation of the URI Thin Film Center (TFC), and describes a diverse array of studies on thin-film materials, substrates, and their processing and analysis. Individual efforts are highlighted in sections on nucleation studies, ion-assisted deposition, Rutherford backscattering spectrometry, Brillouin scattering, a continuum theory of the evolution of structure in thin films, a study of polishing parameters relevant to the preparation of substrates, and the setup of a characterization facility for the Center.

  6. Film Study Hang Ups.

    ERIC Educational Resources Information Center

    Grenier, Charles F.

    1969-01-01

    The interest and delight which students find in film should be preserved from a teacher's excessive zeal to analyze and explain. As the beauty of poetry is frequently diminished through exhaustive analyses of similes, rhyme schemes, and other technical devices, the value of film to high school students can be weakened through too great an emphasis…

  7. Film Study: A Resource Guide.

    ERIC Educational Resources Information Center

    Manchel, Frank

    This resource guide describes six popular approaches to the study of the cinema and provides a practical analysis of selected books, materials, and information about motion picture rentals. Highlighting this extensive survey of film studies are the annotated, critical bibliographies and filmographies of significant books, articles and films by and…

  8. Radical Voices; A Film Course Study Guide.

    ERIC Educational Resources Information Center

    Kernan, Margot

    The leftist radical ideas current in the 1960s and 1970s are expressed in the films discussed in this cinema study guide. The radical film takes extreme and avant-garde approaches to the somewhat publicly taboo topics of sex, social issues, and religion. Among the films discussed, I AM CURIOUS (YELLOW) and SOMETHING DIFFERENT show women in their…

  9. Study on aluminium-based single films.

    PubMed

    Vinod Kumar, G S; García-Moreno, F; Babcsán, N; Brothers, A H; Murty, B S; Banhart, J

    2007-12-28

    In the present paper the authors studied isolated metallic films made from the same material used for making metallic foams, and then characterised their properties. Metal films were made from a liquid aluminium alloy reinforced with ceramic particles of known concentration. Melts without such particles were also investigated. It is shown that stable films could not be made from Al-Si alloy having no particles, and just extremely thin and fragile films could be made from commercially-pure Al. In contrast, aluminium alloys containing particles such as SiC and TiB(2) allowed pulling thin, stable films, which did not rupture. Significant thinning of films was observed when the particle concentration in the melt decreased. By in situ X-ray monitoring of liquid films during pulling, film thickness and drainage effects within the liquid film could be studied. The morphology and microstructure of films was characterised after solidification. Our work shows that the question of how foams are stabilised can be studied using a simplified system such as a film, instead of having to deal with the multitude of different structural elements present in a foam. PMID:18060172

  10. Study of diamond film growth and properties

    NASA Technical Reports Server (NTRS)

    Albin, Sacharial

    1990-01-01

    The objective was to study diamond film growth and its properties in order to enhance the laser damage threshold of substrate materials. Calculations were performed to evaluate laser induced thermal stress parameter, R(sub T) of diamond. It is found that diamond has several orders of magnitude higher in value for R(sub T) compared to other materials. Thus, the laser induced damage threshold (LIDT) of diamond is much higher. Diamond films were grown using a microwave plasma enhanced chemical vapor deposition (MPECVD) system at various conditions of gas composition, pressure, temperature, and substrate materials. A 0.5 percent CH4 in H2 at 20 torr were ideal conditions for growing of high quality diamond films on substrates maintained at 900 C. The diamond films were polycrystalline which were characterized by scanning electron microscopy (SEM) and Raman scattering spectroscopy. The top surface of the growing film is always rough due to the facets of polycrystalline film while the back surface of the film replicates the substrate surface. An analytical model based on two dimensional periodic heat flow was developed to calculate the effective in-plane (face parallel) diffusivity of a two layer system. The effective diffusivity of diamond/silicon samples was measured using a laser pulse technique. The thermal conductivity of the films was measured to be 13.5 W/cm K, which is better than that of a type Ia natural diamond. Laser induced damage experiments were performed on bare Si substrates, diamond film coated Si, and diamond film windows. Significant improvements in the LIDT were obtained for diamond film coated Si compared to the bare Si.

  11. Study of iron mononitride thin films

    SciTech Connect

    Tayal, Akhil Gupta, Mukul Phase, D. M. Reddy, V. R. Gupta, Ajay

    2014-04-24

    In this work we have studied the crystal structural and local ordering of iron and nitrogen in iron mononitride thin films prepared using dc magnetron sputtering at sputtering power of 100W and 500W. The films were sputtered using pure nitrogen to enhance the reactivity of nitrogen with iron. The x-ray diffraction (XRD), conversion electron Mössbauer spectroscopy (CEMS) and soft x-ray absorption spectroscopy (SXAS) studies shows that the film crystallizes in ZnS-type crystal structure.

  12. Radiochromic dye film studies for brachytherapy applications.

    PubMed

    Martínez-Dávalos, A; Rodríguez-Villafuerte, M; Díaz-Perches, R; Arzamendi-Pérez, S

    2002-01-01

    Commercial radiochromic dye films have been used in recent years to quantify absorbed dose in several medical applications. In this study we present the characterisation of the GafChromic MD-55-2 dye film, a double sensitive layer film suitable for photon irradiation in brachytherapy applications. Dose measurements were carried out with a low dose rate 137Cs brachytherapy source, which produces very steep dose gradients in its vicinity, and therefore requires the capability of producing high spatial resolution isodose curves. Quantification of the dose rate in water per unit air kerma strength was obtained using a high-resolution transmission commercial scanner (Agfa DuoScan T1200 with the capability of digitising up to 600 x 1200 pixels per inch using 36 bits per pixel, together with optical density measurements. The Monte Carlo calculations and experimental measurements compared well in the 0-50 Gy dose interval used in this study. PMID:12382798

  13. Study of Fe-Co Nanocomposite Films

    SciTech Connect

    Lancok, A.; Klementova, M.; Kohout, J.; Miglierini, M.; Fendrych, F.; Lancok, J.

    2010-07-13

    Moessbauer study of nanogranular ferromagnetic FeCo films is presented. Two ways of production of nanocomposite systems were employed: (i) hollow cathode plasma jet deposition process, and (ii) laser ablation from Fe-Co metallic targets by means of a KrF excimer laser and r.f. magnetron sputtering. Complementary information on the composition of the samples were obtained by nuclear magnetic resonance of {sup 57}Fe and {sup 59}Co nuclei, conversion electron Moessbauer spectroscopy, and high resolution transmission electron microscopy. The films contain crystalline nanoparticles, 5-20 nm in size, embedded in an amorphous matrix.

  14. Implementing the Study of Multicultural Aesthetics in Film and Video.

    ERIC Educational Resources Information Center

    Gutenko, Gregory

    Film and television in the western world are highly stylized and culturally specific products. A course on multicultural aesthetics in film and video should introduce the student to perceptual alternatives in film and television use. Some of these alternatives can be derived from three well-established areas of film/television study: the…

  15. Film as Revolutionary Weapon: A Pedagogical Analysis. Latin American Studies Program, Film Series No. 3.

    ERIC Educational Resources Information Center

    California Univ., Riverside. Latin American Studies Program.

    This paper describes a university course designed to examine the use of film as a revolutionary medium in Latin American countries. Objectives of the course were to illustrate the complexity of studying a film genre, develop an analytical framework for comparing revolutionary films, and encourage students to reach their own conclusions about the…

  16. Radiation resistance studies of amorphous silicon films

    NASA Technical Reports Server (NTRS)

    Payson, J. Scott; Woodyard, James R.

    1988-01-01

    A study of hydrogenated amorphous silicon thin films irradiated with 2.00 MeV helium ions using fluences ranging from 1E11 to 1E15/sq cm is presented. The films were characterized using photothermal deflection spectroscopy, transmission and reflection spectroscopy, and photoconductivity and annealing measurements. Large changes were observed in the subband-gap optical absorption for energies between 0.9 and 1.7 eV. The steady-state photoconductivity showed decreases of almost five orders of magnitude for a fluence of 1E15/sq cm, but the slope of the intensity dependence of the photoconductivity remained almost constant for all fluences. Substantial annealing occurs even at room temperature, and for temperatures greater than 448 K the damage is completely annealed. The data are analyzed to describe the defects and the density of states function.

  17. Recent Developments in the Rhetorical Study of Film and Television.

    ERIC Educational Resources Information Center

    Benson, Tom

    Rhetorical studies of film and television arose more or less independently at a number of universities during the 1960s and 1970s. At Cornell University (New York), the accident of a combined speech and drama department gave rise to the study of the rhetoric of film. At the same time, other theorists were approaching film rhetoric from literature.…

  18. Reel Teaching = Real Learning: Motivating Reluctant Students through Film Studies

    ERIC Educational Resources Information Center

    Smilanich, Brad; Lafreniere, Nicole

    2010-01-01

    The authors provide a rationale for the critical study of film texts in the English language arts. For struggling or reluctant students, film offers an accessibility that the printed text may not. Students who are intimidated by, or impeded from, accessing print text are able to discuss film with acuity and insight. The study of visual texts can…

  19. Structural studies of ultrathin organic films

    NASA Astrophysics Data System (ADS)

    Yim, Hyun

    1998-11-01

    Ultrathin organic films have been a focus of research due to the growing interest in optoelectronics and molecular electronics. In both areas, it is believed that self-assembled (SA) films and Langmuir-Blodgett (LB) films may provide the desired control of order at the molecular level. The tethering of polyglutamate molecules to surfaces is of special interest due to nonlinear optical properties which can be achieved when the molecules are oriented. The tethering of poly(benzyl-L-glutamate) to silicon has been done by polymerization of benzyl-L-glutamate-N-carboxyanhydride using self-assembled monolayers with various concentrations of amino end groups as initiating layers. X-ray reflectivity results show that a minimum concentration of initiator sites on the surface is required. The second tethering system is a polystyrene brush. The polystyrene brush is expected to give strong sensitivity to solvent swelling. The structure of the polystyrene brush, which was chemically grafted to a substrate, in poor solvent and its change at different temperatures were investigated by neutron reflectometry. When temperature increases up to 30sp°C, both the thickness and roughness increase greatly, which indicates that the polystyrene brush changes from a collapsed state to a theta state. Hairy-rod polyimide molecules are of interest due to their interesting physical properties. Multilayer films of preformed polyimide molecules (6FDA-C18) have been obtained for the first time by the LB technique. The multilayer films do not display a distinctively periodic structure. Upon annealing for a few hours at 180sp°C, the structure relaxes slightly. The alkyl side chain substituted polyimides (BACBF/BPDA) can form metastable monolayers for which the pressure-area isotherms vary markedly with side chain length. For the polyimide with octadecyl side chains, a sharp reduction in zero pressure area occurs between 20 and 24sp°C, suggesting an important change in side chain mobility

  20. Polyethylene terephthalate thin films; a luminescence study

    NASA Astrophysics Data System (ADS)

    Carmona-Téllez, S.; Alarcón-Flores, G.; Meza-Rocha, A.; Zaleta-Alejandre, E.; Aguilar-Futis, M.; Murrieta S, H.; Falcony, C.

    2015-04-01

    Polyethylene Terephthalate (PET) films doped with Rare Earths (RE3+) have been deposited on glass by spray pyrolysis technique at 240 °C, using recycled PET and (RE3+) chlorides as precursors. Cerium, terbium, dysprosium and europium were used as dopants materials, these dopants normally produce luminescent emissions at 450, 545, 573 and 612 nm respectively; the doped films also have light emissions at blue, green, yellow and red respectively. All RE3+ characteristic emissions were observed at naked eyes. Every deposited films show a high transmission in the visible range (close 80% T), films surfaces are pretty soft and homogeneous. Films thickness is around 3 μm.

  1. Dynamic Metabolism Studies of Live Bacterial Films

    SciTech Connect

    Majors, Paul D.; Mclean, Jeffrey S.

    2008-11-01

    Bacterial film (biofilm) microbes exist within spatial (nutrient, electron-acceptor, pH, etc.) gradients of their own making. Correspondingly, biofilm bacteria are physiologically and functionally distinct from free-floating bacteria and from their own species at differing biofilm depths. This article describes our efforts to develop noninvasive nuclear magnetic resonance (NMR) technologies for biofilm-metabolism studies. This involves integrating NMR with controlled-cultivation methods to interrogate microbial physiology live and under known growth conditions. NMR is uniquely capable of providing depth-resolved metabolic and transport information in a non-invasive, non-sample-consuming fashion, providing information required for experimental reactive transport studies. We have studied mono-species biofilms relevant to environment remediation and human health. We describe these technologies, discuss their advantages and limitations, and give examples of their application.

  2. Experimental study of drop impacts on soap films

    NASA Astrophysics Data System (ADS)

    Yawar, Ali; Basu, Saikat; Concha, Andres; Bandi, Mahesh

    2015-11-01

    Impinging drops on flowing and static soap films demonstrate at least three distinct types of impact regimes: (a) the drop bounces off the film surface, (b) it coalesces with the downstream flow for a moving film and for static films it gets assimilated within the film, and (c) it pierces through the film. The interaction presents a unique opportunity to explore the impact of a quasi one-dimensional object on a two-dimensional fluid, much like a comet impacting on a thin atmosphere. We present a detailed experimental study of droplet impacts on soap film flow, for a number of film inclination angles and falling heights of the drop. Imaging techniques employed include sodium lamp interferometry to measure film thickness fluctuations and particle tracking velocimetry to measure the velocity field. Film thickness measures approximately 10 microns and the drop diameter is 1 mm. We mostly observe the bouncing-off regime for smaller inclination angles. However, at higher impact angles, puncturing of the film becomes a more common occurrence. We show that when the drop bounces off the film, there is a momentum transfer leading to vortex dipole shedding, along with the generation of capillary waves; an impulsive regime that may share correspondence with the locomotion of water striders.

  3. Thin teflon-like films for MEMS: Film properties and reliability studies

    SciTech Connect

    Smith, B.K.; LaVigne, G.; Sniegowski, J.J.; Brown, C.D.

    1998-07-01

    This work presents film properties and initial reliability studies for thin Teflon-like films applied to a unique test vehicle, the Sandia-designed and fabricated microengine. Results on microengines coated with the film show a factor of three improvement in their lifetime and an order of magnitude reduction in the coefficient of friction when compared to uncoated samples. Coefficients Of Friction (COF) of 0.07 for the Teflon-like film and 1.0 for uncoated samples are extracted from models which match the measured behavior of working microengines. These films, deposited form a plasma source, exhibit the ability to penetrate into very narrow, deep channels common to many MEMS devices. For as-deposited film, both the refractive index at 1.4 and the contact angle with water at 108{degree} show the film to be very similar to bulk Teflon PTFE. Film stability as a function of temperature has been examined using Fourier Transformation Infrared (FTIR) spectroscopy. The film structure as observed by the fluorine-carbon (F-C) peak is stable up to 200 C, but starts decomposing above 250 C. Film composition has been examined using X-ray photoelectron spectroscopy (XPS) and is quite different for directly exposed surfaces compared with deep, narrow channels where the deposition process is diffusion limited.

  4. Micromagnetic studies of thin metallic films (invited)

    NASA Astrophysics Data System (ADS)

    Zhu, Jian-Gang; Bertram, H. Neal

    1988-04-01

    A computer simulation model has been developed to conduct micromagnetic studies of thin magnetic films. Thin-film media are modeled as a planar hexagonal array of hexagonally shaped grains. Each grain is a single domain particle whose magnetization reverses by coherent rotation. The computation utilizes coupled gyromagnetic dynamic equations with phenomenological Landau-Lifshitz damping. In particular, the effects of particle interactions are investigated. The effect of media microstructure on magnetic hysteresis is examined as well as the effect of intergranular exchange coupling. The difference between planar and completely random orientation of the crystalline anisotropy axes is discussed. Recorded transitions are simulated by allowing a pair of perfect transitions to relax. With no intergranular exchange coupling, the transitions show profound irregularity and zig-zag structure. Intergranular exchange coupling produces more uniform transitions with increased zig-zag structure amplitude. For a closely spaced transition pair, the equilibrium configuration yields percolated transition boundaries with stable reverse island domains. The effect of gyromagnetic precession also has been examined.

  5. Studies of Niobium Thin Film Produced by Energetic Vacuum Deposition

    SciTech Connect

    Genfa Wu; Anne-Marie Valente; H. Phillips; Haipeng Wang; Andy Wu; T. J. Renk; P Provencio

    2004-05-01

    An energetic vacuum deposition system has been used to study deposition energy effects on the properties of niobium thin films on copper and sapphire substrates. The absence of working gas avoids the gaseous inclusions commonly seen with sputtering deposition. A biased substrate holder controls the deposition energy. Transition temperature and residual resistivity ratio of the niobium thin films at several deposition energies are obtained together with surface morphology and crystal orientation measurements by AFM inspection, XRD and TEM analysis. The results show that niobium thin films on sapphire substrate exhibit the best cryogenic properties at deposition energy around 123 eV. The TEM analysis revealed that epitaxial growth of film was evident when deposition energy reaches 163 eV for sapphire substrate. Similarly, niobium thin film on copper substrate shows that film grows more oriented with higher deposition energy and grain size reaches the scale of the film thickness at the deposition energy around 153 eV.

  6. Educational Film Guide for Middle Eastern Studies.

    ERIC Educational Resources Information Center

    Greenman, Joseph; Joachim, Ann

    This annotated guide lists 16mm. films on the Middle East for use in grades K-12 and with adults. The Middle East refers to a vast area extending from eastern Afghanistan and the northern Caucasus to the western coast of Morocco and the southern periphery of the Sahara. The guide does not list films according to their merits. Rather, it includes…

  7. New Water Vapor Barrier Film Based on Lamellar Aliphatic-Monoamine-Bridged Polysilsesquioxane.

    PubMed

    Zhang, Cong; Zhang, Ce; Ding, Ruimin; Cui, Xinmin; Wang, Jing; Zhang, Qinghua; Xu, Yao

    2016-06-15

    Siloxane-based hybrid lamellar materials with ordered nanostructure units paralleling to the substrate have been widely used for water vapor barrier. However, it is very difficult to control the orientation of the lamellar units at molecular level. In this Research Article, a new lamellar bridged polysilsesquioxane (BPSQ) film, whose voids between lamellae were filled by pendant alkyl chains in the organic bridge, was prepared via the stoichiometric reaction between 3-glycidoxypropyltrimethoxysilane and aliphatic monoamine at 60 °C without catalyst. Experimental evidence obtained from FT-IR, MS, NMR, and GIXRD techniques suggested that the as-prepared BPSQ films were constructed by lamellar units with disordered orientation. Nonetheless, they possessed satisfactory water vapor barrier performance for potassium dihydrogen phosphate (KDP) and deuterated potassium dihydrogen phosphate (DKDP) optical crystals, and the water vapor transmission rate through BPSQ film with thickness of 25 μm was as low as 20.3 g·m(-2)·d(-1). Those results proved that filling the voids between molecular lamellae with alkyl chains greatly weakened the effect of lamellar unit orientation on the vapor barrier property of BPSQ film. PMID:27224032

  8. Structural and Other Studies of Langmuir-Blodgett Films.

    NASA Astrophysics Data System (ADS)

    Prakash, Maneesha

    Certain organic materials comprised of ampiphilic molecules will spread on the surface of water to form monolayer films known as Langmuir films. These films can be transferred to solid substrates by dipping the substrates in and out of the water. The films transfer to the substrates monolayer by monolayer and the resulting built-up films are known as Langmuir-Blodgett films. Langmuir-Blodgett films are very regular, with the planes aligned parallel to a high degree. This technique has potential for building structures that may exhibit unusual mechanical, optical, magnetic or electronic properties. Because the proposed uses of Langmuir-Blodgett films depend in a fundamental way on their structure, structural studies of Langmuir-Blodgett films are of great relevance. We have made Langmuir and Langmuir-Blodgett films of simple materials for the purpose of x-ray diffraction characterization. We have looked for differences between the structure of the materials in bulk form as compared with the structure in Langmuir -Blodgett film form. We have studied the in-plane structure of films of the lead salts of various fatty acids using both an external reflection geometry for samples made on glass slide substrates, and a transmission geometry for samples made on thin single crystal mica substrates. Information concerning the in-plane structure and correlations between the layers has been obtained. For the samples made on single crystal mica substrates, epitaxial growth has been observed, whereas on glass substrates the samples have been found to be powders in the plane. An anomalous intensity pattern has been observed for the in-plane and out-of-the -plane peaks. We have proposed a positioning of the hydrocarbon chans that nicely explains the data. We have investigated the conditions for transfer of films on the lipid dipalmitoylphosphatidylcholine, a primary consituent of cell membranes. We have succeeded in forming Langmuir-Blodgett films of this material by the addition of

  9. Reading in the Social Studies: Using Subtitled Films

    ERIC Educational Resources Information Center

    Holmes, Kerry; Russell, William B., III; Movitz, Allison

    2007-01-01

    Involving reluctant and low-achieving students with reading is an essential step to increasing students' content area knowledge. One way to increase students' engagement with text is by linking social studies content with foreign films that have English subtitles. Not only can subtitled films help increase students' engaged time with text, but the…

  10. Drying of polymer films: study of demixing phenomena

    NASA Astrophysics Data System (ADS)

    Fichot, Julie; Heyd, Rodolphe; Saboungi, Marie-Louise; Josserend, Christophe; Combard, Emilie; Tranchant, Jean Francois

    2011-03-01

    Understanding the mechanisms that control the stability of polymeric films is important in beauty care. We have prepared films starting from a water-soluble organic polymer, a preservative and water. We study the drying of these films as a function of several physicochemical parameters that control their interfaces such as temperature, humidity and the nature of the support. The viscoelastic properties of the solutions before spreading out are analyzed with a rheometer in order to adjust the temperature. The topography of the films is observed by optical microscopy and the evolution of the drying is determined with a precision gravimetric balance. The behavior of the films on a nanometric scale is followed by AFM. During the drying process, droplets appear on the surface of the film, made up of water surrounded by a shell of preservative. As the films dries, the water evaporates from the droplets and the preservative spreads on the surface of the film, leading to the formation of craters on the surface of the dried film. The dimensions and numbers of the craters depend strongly on the type and concentration of the preservative employed.

  11. Feasibility Study of Thin Film Thermocouple Piles

    NASA Technical Reports Server (NTRS)

    Sisk, R. C.

    2001-01-01

    Historically, thermopile detectors, generators, and refrigerators based on bulk materials have been used to measure temperature, generate power for spacecraft, and cool sensors for scientific investigations. New potential uses of small, low-power, thin film thermopiles are in the area of microelectromechanical systems since power requirements decrease as electrical and mechanical machines shrink in size. In this research activity, thin film thermopile devices are fabricated utilizing radio frequency sputter coating and photoresist lift-off techniques. Electrical characterizations are performed on two designs in order to investigate the feasibility of generating small amounts of power, utilizing any available waste heat as the energy source.

  12. Radiation resistance studies of amorphous silicon films

    NASA Technical Reports Server (NTRS)

    Woodyard, James R.; Payson, J. Scott

    1989-01-01

    Hydrogenated amorphous silicon thin films were irradiated with 2.00 MeV helium ions using fluences ranging from 1E11 to 1E15 cm(-2). The films were characterized using photothermal deflection spectroscopy and photoconductivity measurements. The investigations show that the radiation introduces sub-band-gap states 1.35 eV below the conduction band and the states increase supralinearly with fluence. Photoconductivity measurements suggest the density of states above the Fermi energy is not changing drastically with fluence.

  13. Cratering Studies in Thin Plastic Films

    NASA Astrophysics Data System (ADS)

    Shu, A. J.; Bugiel, S.; Gruen, E.; Hillier, J. K.; Horanyi, M.; Munsat, T.

    2012-12-01

    Thin plastic films, such as Polyvinylidene Fluoride (PVDF), have been used as protective coatings or dust detectors on a number of missions including the Dust Counter and Mass Analyzer (DUCMA) instrument on Vega 1 and 2, the High Rate Detector (HRD) on the Cassini Mission, and the Student Dust Counter (SDC) on New Horizons. These types of detectors can be used on the lunar surface or in lunar orbit to detect dust grain size distributions and velocities. Due to their low power requirements and light weight, large surface area detectors can be built for observing low dust fluxes. The SDC dust detector is made up of a permanently polarized layer of PVDF coated on both sides with a thin layer (≈ 100 nm) of aluminum nickel. The operation principle behind this type of detector is that a micrometeorite impact removes a portion of the metal surface layer exposing the permanently polarized PVDF underneath. This causes a local potential near the crater changing the surface charge of the metal layer. The dimensions of the crater determine the strength of the potential and thus the signal generated by the PVDF. The theory uses a crater diameter scaling law which was not intended for use with PVDF. Work is being undertaken to develop a new crater diameter scaling law using iron particles in 52 μm thick PVDF. Samples were brought to the Heidelberg Dust Accelerator and exposed to a selected range of mass and velocities. Samples are being analyzed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) using 3D reconstruction photogrammetry using stereo pairs taken in a scanning electron microscope (SEM) and cross sections taken in a focused ion beam (FIB). Further work is planned at the CCLDAS dust accelerator.

  14. Spectroscopic studies of refractory and dielectric thin films

    SciTech Connect

    Truong, C.M.

    1993-01-01

    This work demonstrated the application of the techniques and methodology of surface science to investigate the mechanisms of thin film deposition processes on solid surfaces. The synthesis of boron nitride (BN) thin films was studied using X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). In this model system, diborane (B[sub 2]H[sub 6]), ammonia (NH[sub 3]) and hydrazine (N[sub 2]H[sub 4]) were used as precursors to deposit BN thin films on a clean Ru(0001) surface. The result showed that ammonia reaction with diborane yielded only boron-rich boron nitride overlayers. However, stoichiometric BN films in excess of one monolayer could be produced when hydrazine was substituted for ammonia. The effects of oxygen on boron-rich and stoichiometric boron-nitrogen films were also examined. In the second part of this work, high resolution electron energy loss spectroscopy (HREELS) was used to characterize defect centers in MgO and in lithium-doped MgO thin films. The HREELS results showed that MgO thin films grown on Mo(100) were nearly defect-free at temperatures up to 1100 K. HREELS measurements indicated that annealings to higher temperatures induced F-type defect centers in the MgO films. The formation of [Li[sup +]O[sup [minus

  15. Structural study of Ge/GaAs thin films

    NASA Astrophysics Data System (ADS)

    Lazarov, V. K.; Lari, L.; Lytvyn, P. M.; Kholevchuk, V. V.; Mitin, V. F.

    2012-07-01

    Ge/GaAs heterostructure research is largely motivated by the application of this material in solar cells, metal-oxide-semiconductor field-effect transistors, mm-wave mixer diodes, temperature sensors and photodetectors. Therefore, understanding of how the properties of Ge/GaAs heterostructure depend on its preparation (growth) is of importance for various high-efficiency devices. In this work, by using thermal Ge evaporation on GaAs(100), we studied structural properties of these films as a function of the deposition rate. Film grains size and morphology show strong dependence of the deposition rate. Low deposition rates results in films with large crystal grains and rough surface. At high deposition rates films become flatter and their crystal grains size decreases, while at very high deposition rates films become amorphous. Cross-sectional TEM of the films show that the Ge films are granular single crystal epitaxially grown on GaAs. The Ge/GaAs interface is atomically abrupt and free from misfit dislocations. Stacking faults along the [111] directions that originate at the interface were also observed. Finally by using the Kelvin probe microscopy we show that work function changes are related to the grain structure of the film.

  16. Integrating Asian Film into Film Studies and Film Production Courses Using Examples from Yasujiro Ozu (Japan) and Zhang Yimou (China). Asian Studies Module, 1997.

    ERIC Educational Resources Information Center

    Carson, Diane

    This curriculum module offers concrete and specific examples for instructors who wish to integrate the films of Yasujiro Ozu of Japan and Zhang Yimou from China into film studies courses. Through this module, students should learn to compare and contrast conventional screen space, color, and editing to alternative forms. By becoming more familiar…

  17. Study of Langmuir and Langmuir-Blodgett Thin films

    NASA Astrophysics Data System (ADS)

    Goodwin, Ross; Prayaga, Chandra; Wade, Aaron

    Arachidic Acid, Cholesterol, and Stearic Acid thin films were created and studied utilizing the Langmuir method in order to obtain a single molecule or monomolecular layer out of a desired substance at an air-water interface. The phase transitions are observed by measuring the surface pressure vs. area isotherms. Langmuir-Blodgett (LB) films were created on a prepared substrate. The LB film structures were then studied using X-ray Diffraction, and Raman Spectroscopy. UWF Office of Undergraduate Research Project Award, UWF ITEP-Technology Fee Project Award, UWF Quality Enhancement Plan Award.

  18. Film Balance Studies of Membrane Lipids and Related Molecules

    ERIC Educational Resources Information Center

    Cadenhead, D. A.

    1972-01-01

    Discusses apparatus, techniques, and measurements used to determine cell membrane composition. The use of a film balance to study monolayer membranes of selected lipids is described and results reported. (TS)

  19. A thin film hydroponic system for plant studies

    NASA Technical Reports Server (NTRS)

    Hines, Robert; Prince, Ralph; Muller, Eldon; Schuerger, Andrew

    1990-01-01

    The Land Pavillion, EPCOT Center, houses a hydroponic, thin film growing system identical to that residing in NASA's Biomass Production Chamber at Kennedy Space Center. The system is targeted for plant disease and nutrition studies. The system is described.

  20. Study of the photovoltaic effect in thin film barium titanate

    NASA Technical Reports Server (NTRS)

    Grannemann, W. W.; Dharmadhikari, V. S.

    1982-01-01

    Ferroelectric films of barium titanate were synthesized on silicon and quartz substrates, and the photoelectric effect in the structure consisting of metal deposited ferroelectric barium titanate film silicon was studied. A photovoltage with polarity that depends on the direction of the remanent polarization was observed. The deposition of BaTiO3 on silicon and fused quartz substrates was accomplished by an rf sputtering technique. A series of experiments to study the growth of ferroelectric BaTiO3 films on single crystal silicon and fused quartz substrates were conducted. The ferroelectric character in these films was found on the basis of evidence from the polarization electric field hysteresis loops, capacitance voltage and capacitance temperature techniques and from X-ray diffraction studies.

  1. Cryogenic Fluid Film Bearing Tester Development Study

    NASA Technical Reports Server (NTRS)

    Scharrer, Joseph K. (Editor); Murphy, Brian T.; Hawkins, Lawrence A.

    1993-01-01

    Conceptual designs were developed for the determination of rotordynamic coefficients of cryogenic fluid film bearings. The designs encompassed the use of magnetic and conventional excitation sources as well as the use of magnetic bearings as support bearings. Test article configurations reviewed included overhung, floating housing, and fixed housing. Uncertainty and forced response analyses were performed to assess quality of data and suitability of each for testing a variety of fluid film bearing designs. Development cost and schedule estimates were developed for each design. Facility requirements were reviewed and compared with existing MSFC capability. The recommended configuration consisted of a fixed test article housing centrally located between two magnetic bearings. The magnetic bearings would also serve as the excitation source.

  2. Before You Kill the Lights: A Practical Guide to Setting Up a Film Study Program.

    ERIC Educational Resources Information Center

    Greiner, Charles F.

    1979-01-01

    Offers suggestions on how to make a film study course challenging and enjoyable, through using a variety of films, defining visual literacy, choosing films with cinematic and literary value, and deciding on a specific approach for the course. (FL)

  3. Experimental study of uncentralized squeeze film dampers

    NASA Technical Reports Server (NTRS)

    Quinn, R. D.

    1983-01-01

    The vibration response of a rotor system supported by a squeeze film damper (SFD) was experimentally investigated in order to provide experimental data in support of the Rotor/Stator Interactive Finite Element theoretical development. Part of the investigation required the designing and building of a rotor/SFD system that could operate with or without end seals in order to accommodate different SFD lengths. SFD variables investigated included clearance, eccentricity mass, fluid pressure, and viscosity and temperature. The results show inlet pressure, viscosity and clearance have significant influence on the damper performance and accompanying rotor response.

  4. Experimental study of heat transfer to falling liquid films

    NASA Astrophysics Data System (ADS)

    Fagerholm, N. E.; Kivioja, K.; Ghazanfari, A. R.; Jaervinen, E.

    1985-12-01

    This project was initiated in order to obtain more knowledge about thermal design of falling film heat exchangers and to find methods to improve heat transfer in film flow. A short literature survey of film flow characteristics and heat transfer is presented. An experimental apparatus designed and built for studying falling film evaporation is described. The first experiments were made with smooth Cu tube 25/22 mm and refrigerant R114 as evaporating liquid. A significant amount of droplet entrainment was observed during the tests. The measured average heat transfer coefficient varied from 1000 to 1800 W/m K when Re=1300 to 11000 respectively and when the transfer mode is surface evaporation. This could be predicted accurately with the experimental correlation of Chun and Seban. When nucleate boiling is dominant the heat transfer could be predicted well with pool boiling correlation of VDI-84.

  5. Scanning tunneling microscopy studies of diamond films and optoelectronic materials

    NASA Technical Reports Server (NTRS)

    Perez, Jose M.

    1993-01-01

    In this report, we report on progress achieved from 12/1/92 to 10/1/93 under the grant entitled 'Scanning Tunneling Microscopy Studies of Diamond Films and Optoelectronic Materials'. We have set-up a chemical vapor deposition (CVD) diamond film growth system and a Raman spectroscopy system to study the nucleation and growth of diamond films with atomic resolution using scanning tunneling microscopy (STM). A unique feature of the diamond film growth system is that diamond films can be transferred directly to the ultrahigh vacuum (UHV) chamber of a scanning tunneling microscope without contaminating the films by exposure to air. The University of North Texas (UNT) provided $20,000 this year as matching funds for the NASA grant to purchase the diamond growth system. In addition, UNT provided a Coherent Innova 90S Argon ion laser, a Spex 1404 double spectrometer, and a Newport optical table costing $90,000 to set-up the Raman spectroscopy system. The CVD diamond growth system and Raman spectroscopy system will be used to grow and characterize diamond films with atomic resolution using STM as described in our proposal. One full-time graduate student and one full-time undergraduate student are supported under this grant. In addition, several graduate and undergraduate students were supported during the summer to assist in setting-up the diamond growth and Raman spectroscopy systems. We have obtained research results concerning STM of the structural and electronic properties of CVD grown diamond films, and STM and scanning tunneling spectroscopy of carbon nanotubes. In collaboration with the transmission electron microscopy (TEM) group at UNT, we have also obtained results concerning the optoelectronic material siloxene. These results were published in refereed scientific journals, submitted for publication, and presented as invited and contributed talks at scientific conferences.

  6. Study of ordered macroporous polymer films by templating breath figures

    NASA Astrophysics Data System (ADS)

    Song, Lulu

    2005-11-01

    Macroporous films with highly ordered pore patterns have many potential applications. Some examples include microstructured electrode surfaces, photonic band gap materials and filters for cell sorting and bio-interfaces. In this dissertation we discuss a "moist-casting" method to prepare hexagonally-ordered macroporous films with pore sizes in the range of sub-micron to several microns, where condensed water droplets ("breath figures") work as templates. Compared with other templating methods, this one is fast and simple. Well-ordered porous films can be obtained in tens of seconds and the pore size can be easily tailored and dynamically controlled by adjusting the casting conditions. More importantly, there is no need to remove the templates; water droplets just evaporate when the casting processes are finished. This study was carried out with the intention of characterizing the structures, understanding film-formation processes and exploring special properties and possible applications. For the structural characterization, film morphology was studied in detail by normal optical microscopy and laser scanning confocal microscopy (LSCM). Several interesting features have been revealed. Meanwhile, the degree of the order of the porous structures were characterized both in real space via Voronoi diagram and bond-orientational correlation function, and in reciprocal space via Fraunhofer diffraction pattern. To further understand the mechanism, the evaporation of the polymer solutions during the film formation was studied by monitoring their mass over time. Besides, the evolution of breath figures formed on the evaporating polymer solutions was in-situ recorded via a high-speed camera coupled to an optical microscope. Combined with the information on the film structures obtained via LSCM, explanations for some detailed features have been attempted. Wetting property of these films was studied in some detail. The films exhibited "lotus effect", mimicking natural non

  7. The Art of Teaching Social Studies with Film

    ERIC Educational Resources Information Center

    Russell, William B., III

    2012-01-01

    Teaching with film is a powerful and meaningful instructional strategy. This article discusses five classroom-tested methods for teaching with film: (1) film as a visual textbook, (2) film as a depicter of atmosphere, (3) film as an analogy, (4) film as a historiography, and (5) film as a springboard. Each of the methods discussed includes…

  8. Studies on atomic layer deposition of IRMOF-8 thin films

    SciTech Connect

    Salmi, Leo D. Heikkilä, Mikko J.; Vehkamäki, Marko; Puukilainen, Esa; Ritala, Mikko; Sajavaara, Timo

    2015-01-15

    Deposition of IRMOF-8 thin films by atomic layer deposition was studied at 260–320 °C. Zinc acetate and 2,6-naphthalenedicarboxylic acid were used as the precursors. The as-deposited amorphous films were crystallized in 70% relative humidity at room temperature resulting in an unknown phase with a large unit cell. An autoclave with dimethylformamide as the solvent was used to recrystallize the films into IRMOF-8 as confirmed by grazing incidence x-ray diffraction. The films were further characterized by high temperature x-ray diffraction (HTXRD), field emission scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), time-of-flight elastic recoil detection analysis (TOF-ERDA), nanoindentation, and energy-dispersive x-ray spectroscopy. HTXRD measurements revealed similar behavior to bulk IRMOF-8. According to TOF-ERDA and FTIR, composition of the films was similar to IRMOF-8. Through-porosity was confirmed by loading the films with palladium using Pd(thd){sub 2} (thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) as the precursor.

  9. Studies of falling annular films, Parts I and II

    SciTech Connect

    Roidt, R.M.; Evans, R.A.

    1989-01-01

    New environmental requirements and restrictions necessitate exploration of new methods for controlling and containing various chemicals and chemical reactions. A novel method of exercising such control is based upon the cylindrical film reactor, a device originally studied as a confinement for a fusion reactor. The films used in these confinement models were quite thick relative to the radius of the cylindrical film so that the experimental work was generally not relevant to the design of chemical reactors where, for purposes of efficiency, the minimum confinement flowrate is desired. An annular, cylindrical, falling film converges into a single stream due to surface tension forces; this convergence length determines the volume of the reactor. Entrainment of gases from within the film volume to the exit stream allows a constant feed of gas into the reactor volume so that gas phase reactions may be carried out without contact with surrounding atmosphere. The present work is an experimental investigation of the pertinent parameters and stability criteria for thin, falling, cylindrical films. We find that, while only for relatively restricted ratios of gas to liquid flow rates do stable reaction volumes exist, most of this range lies within flow rate limits which may be of use in gas-liquid chemical reactors. 12 refs., 33 figs.

  10. Polycrystalline Thin Film Device Degradation Studies

    SciTech Connect

    Albin, D. S.; McMahon, T. J.; Pankow, J. W.; Noufi, R.; Demtsu, S. H.; Davies, A.

    2005-11-01

    Oxygen during vapor CdCl2 (VCC) treatments significantly reduced resistive shunts observed in CdS/CdTe polycrystalline devices using thinner CdS layers during 100 deg C, open-circuit, 1-sun accelerated stress testing. Cu oxidation resulting from the reduction of various trace oxides present in as-grown and VCC treated films is the proposed mechanism by which Cu diffusion, and subsequent shunts are controlled. Graphite paste layers between metallization and CdTe behave like diffusion barriers and similarly benefit device stability. Ni-based contacts form a protective Ni2Te3 intermetallic layer that reduces metal diffusion but degrades performance through increased series resistance.

  11. Film-In: A Study of the Movies, A Resource Unit.

    ERIC Educational Resources Information Center

    Vaughn, Mary Beth

    This resource guide to films contains four study units for high school students dealing with (1) reasons for film popularity--involvement; (2) film language--visual, motion, sound; (3) thematic study--a perspective on war; (4) film criticism--sensitivity and awareness. Each unit provides suggestions for length of study, purposes, descriptions of…

  12. A finite element study of piezoelectric thin films on substrates

    NASA Astrophysics Data System (ADS)

    Liu, Bo

    The overall goal of this work has been mainly to advance the understanding of the degradation in the response of piezoelectric thin films after they are deposited on substrates. To have better understanding of the difference in the response between free standing piezoelectric films and those deposited on a substrate, we calculated the normalized "effective" piezoelectric coefficients for BT/MgO, PZT/STO and ZnO/STO respectively. We also studied the impact on the effective coefficients due to the components of the bulk material's piezoelectric coefficients. After studying the clamping effects of the substrate, lattice mismatch, stiffness of the films and the substrates, we found that a periodic structure of piezoelectric thin films on substrates is a useful approach to overcome the degradation of the piezoresponse. Further, if non-piezoelectric islands are inserted between the periodic piezoelectric islands, there is an additional contribution that improves the piezoresponse of the piezoelectric films; we refer to this structure as a bi-island periodic structure. The bi-island structure may also be used as a hybrid device if the non-piezoelectric islands have special properties, e.g. piezomagnetism, ferromagnetism and shape memory. The hybrid device may thus be used for signal transduction, e.g. converting electrical signals to magnetic/mechanical/thermal signals and vice-versa, as well as energy harvesting.

  13. Microwave study of superconducting Sn films above and below percolation

    NASA Astrophysics Data System (ADS)

    Beutel, Manfred H.; Ebensperger, Nikolaj G.; Thiemann, Markus; Untereiner, Gabriele; Fritz, Vincent; Javaheri, Mojtaba; Nägele, Jonathan; Rösslhuber, Roland; Dressel, Martin; Scheffler, Marc

    2016-08-01

    The electronic properties of superconducting Sn films ({T}{{c}}≈ 3.8 {{K}}) change significantly when reducing the film thickness down to a few {nm}, in particular close to the percolation threshold. The low-energy electrodynamics of such Sn samples can be probed via microwave spectroscopy, e.g. with superconducting stripline resonators. Here we study Sn thin films, deposited via thermal evaporation—ranging in thickness between 38 and 842 {nm}—which encompasses the percolation transition. We use superconducting Pb stripline resonators to probe the microwave response of these Sn films in a frequency range between 4 and 20 {GHz} at temperatures from 7.2 down to 1.5 {{K}}. The measured quality factor of the resonators decreases with rising temperature due to enhanced losses. As a function of the sample thickness we observe three regimes with significantly different properties: samples below percolation, i.e. ensembles of disconnected superconducting islands, exhibit dielectric properties with negligible losses, demonstrating that macroscopic current paths are required for appreciable dynamical conductivity of Sn at GHz frequencies. Thick Sn films, as the other limit, lead to low-loss resonances both above and below T c of Sn, as expected for bulk conductors. But in an intermediate thickness regime, just above percolation and with labyrinth-like morphology of the Sn, we observe a quite different behavior: the superconducting state has a microwave response similar to the thicker, completely covering films with low microwave losses; but the metallic state of these Sn films is so lossy that resonator operation is suppressed completely.

  14. Cratering Studies in Thin Plastic Films

    NASA Astrophysics Data System (ADS)

    Shu, Anthony; Bugiel, S.; Gruen, E.; Horanyi, M.; Munsat, T.; Srama, R.; Colorado CenterLunar Dust; Atmospheric Studies (CCLDAS) Team

    2013-10-01

    Thin plastic films, such as Polyvinylidene Fluoride (PVDF), have been used as protective coatings or dust detectors on a number of missions including the Dust Counter and Mass Analyzer (DUCMA) instrument on Vega 1 and 2, the High Rate Detector (HRD) on the Cassini Mission, and the Student Dust Counter (SDC) on New Horizons. These types of detectors can be used on the lunar surface or in lunar orbit to detect dust grain size distributions and velocities. Due to their low power requirements and light weight, large surface area detectors can be built for observing low dust fluxes. The SDC dust detector is made up of a permanently polarized layer of PVDF coated on both sides with a thin layer (≈ 1000 Å) of aluminum nickel. The operation principle is that a micrometeorite impact removes a portion of the metal surface layer exposing the permanently polarized PVDF underneath. This causes a local potential near the crater changing the surface charge of the metal layer. The dimensions of the crater determine the strength of the potential and thus the signal generated by the PVDF. The theoretical basis for signal interpretation uses a crater diameter scaling law which was not intended for use with PVDF. In this work, a crater size scaling law has been experimentally determined, and further simulation work is being done to enhance our understanding of the mechanisms of crater formation. Two Smoothed Particle Hydrodynamics (SPH) codes are being evaluated for use as a simulator for hypervelocity impacts: Ansys Autodyn and LS-Dyna from the Livermore Software Technology Corp. SPH is known to be well suited to the large deformities found in hypervelocity impacts. It is capable of incorporating key physics phenomena, including fracture, heat transfer, melting, etc. Furthermore, unlike Eulerian methods, SPH is gridless allowing large deformities without the inclusion of unphysical erosion algorithms. Experimental results and preliminary simulation results and conclusions will be

  15. Study of critical current density in superconducting magnesium diboride films grown by ex situ annealing of CVD boron films

    NASA Astrophysics Data System (ADS)

    Hanna, Mina

    MgB2 films have been processed by different techniques, the most successful of which include the hybrid physical-chemical vapor deposition (HPCVD) as well as the ex situ high temperature annealing of boron films in Mg vapor. The advantage of the ex situ method is that it allows the coating of MgB2 on large and complex surfaces, such as superconducting radio frequency (RF) cavities. However, it has always been realized that HPCVD films can carry higher J c than the ex situ annealed films. In this research, we succeeded in fabricating high quality MgB2 films by the ex situ annealing technique that produced a Jc value as high as 1.8 x 106 A/cm 2 for 1 mum thick film at 20 K and self-field. This high Jc value is, however, considerably reduced at higher thicknesses similar to that observed in YBCO coated conductors. In order to understand the mechanisms responsible for J c decrease with increasing film thickness, we studied the Jc behavior as a function of thickness in MgB2 films fabricated by ex situ annealing at 840°C of boron films, grown by chemical vapor deposition, in Mg vapor. The film thickness ranged between 300 nm and 10 mum. The values of Jc for these films ranged from 1.2 x 107 A/cm2 for 300 nm to 1.9 x 105 A/cm2 for 10 mum film thickness at 20 K and self-field. In addition, the results show that critical current (Ic) reaches a maximum value of 728 A/cm width at ˜1 mum thick MgB2 film at 20 K and self-field. These results of Jc and Ic behaviors with higher thickness are interpreted in terms of impurity diffusion during annealing and microstructural degradation for thicker films.

  16. Using stressful films to analyze risk factors for PTSD in analogue experimental studies--which film works best?

    PubMed

    Weidmann, Anke; Conradi, Ania; Groger, Kathrin; Fehm, Lydia; Fydrich, Thomas

    2009-10-01

    To understand mental disorders, analogue paradigms provide an indispensable contribution. In posttraumatic stress disorder (PTSD), the stressful film paradigm is a frequently used analogue approach: Films depicting traumatic events are shown to non-clinical participants in order to elicit stress responses analogue to responses to traumatic events in real life. Previous studies used a large variety of films, which is problematic with regard to the comparability of results. The main goal of this study was to identify a film clip that (a) consistently provokes stress reactions and (b) provokes reactions that are as similar as possible to traumatic stress. We randomly exposed 105 male and female participants to one of four stressful films, differing, e.g., in content and origin. Intrusive memories of the film, reported immediately after the film and during a diary phase of three days, as well as distress, heart rate, and several mood states were measured. A film clip depicting rape elicited the most consistent reactions that were characterized by a higher heart rate, more distress and more intrusive memories, compared to the other three clips. Intrusive memories across all films were especially related to an increase in heart rate and disgust in response to the film. PMID:19347765

  17. Nanoindentation and scratch studies on magnetron sputtered Ti thin films.

    PubMed

    Kataria, S; Ramaseshan, R; Dash, S; Tyagi, A K

    2009-09-01

    Ti thin films sputter deposited on D9 steel at two different temperatures were studied for their mechanical behavior under static and sliding contact conditions using nanoindentation and scratch tests. The film hardness measured at the surface of the coatings exhibited a value of 2.5 GPa, for both conditions. From the scratch test, it is understood that coatings deposited at 200 degrees C substrate temperature showed superior adhesion strength. Critical load to failure for these coatings was evaluated at 2 N. PMID:19928247

  18. In situ studies of grain growth in thin metal films

    SciTech Connect

    Nichols, C.S.; Mansuri, C.M. . Dept. of Materials Science and Engineering); Townsend, S.J. . Dept. of Physics); Smith, D.A. . T.J. Watson Research Center)

    1993-06-01

    Grain growth in thin films of aluminum has been studied using in situ transmission electron microscopy and a heating stage. Videotapes taken during grain growth were analyzed with the intent of searching for the predominant local rearrangement processes responsible for growth. Evolution of a soap froth can be decomposed into only two elementary local topology rearranging events. The authors have found numerous exceptions to prevailing theories that compare grain growth in thin films to the evolution of such froths. These observations suggest that a more complete picture of grain growth is necessary and that such a theory must include more complex local rearrangement processes.

  19. Experimental study of flapping jets in a soap film

    NASA Astrophysics Data System (ADS)

    Lee, Julia; Kim, Ildoo; Mandre, Shreyas

    2015-11-01

    Plateau and Rayleigh's observation and explanation on jet instability have inspired us over the years and there has been a significant advance in understanding the jet dynamics. Here, we present a quasi-two-dimensional experimental study of flapping jets in a soap film. Newtonian and non-Newtonian solutions are injected in a flowing soap film. Thinning, break-ups, and beads-on-a-string of the jets, and axisymmetric vortices shredded from the flapping jets are visualized. We employ PIV of the flow motion around the jets to gain an understanding of the roles of instabilities in the flow.

  20. Infrared spectroscopic study of sputtered tungsten oxide films

    SciTech Connect

    Paul, J.L.; Lassegues, J.C. )

    1993-10-01

    Recent infrared and Raman spectroscopic studies of various tungsten oxide films concluded either the formation of W=O terminal bonds or the transformation of such bonds into W-OH groups upon proton insertion. The infrared transmission and reflection spectra of bleached and colored sputtered films were reinvestigated in order to resolve the previous contradictory interpretations and for better insight into the mechanism of electrochromism at the molecular level. The new results confirm the first interpretation and allow us to show that H[sup +] or Li[sup +] insertion creates shorter ([approximately]1.7[angstrom]) and longer ([approximately]2 [angstrom]) W-O bonds around the W[sup 5+] centers. These results are in agreement with the concepts of small polaron and of intervalence charge transfer mechanism. They illustrate the local lattice distortion around a W[sup 5+] site. Aging of the initial films has also been followed and characterized by H/D in situ isotopic exchange.

  1. Mössbauer and SEM study of Fe Al film

    NASA Astrophysics Data System (ADS)

    Sebastian, Varkey; Sharma, Ram Kripal; Lakshmi, N.; Venugopalan, K.

    2006-04-01

    Fe Al alloy with Fe/Al ratio of 3:1 was first prepared by argon arc melting. It was subsequently coated on glass slide and cellophane tape using an electron beam gun system to have a thickness of 2,000 Å. X-ray diffraction spectrum of the coated sample indicates a definite texture for the film with a preferential growth along the Fe(110) plane. SEM micrographs of the film showed the presence of nano islands of nearly 3 × 1012/m2 surface density. Composition of different parts of the film was determined using EDAX. Room temperature Fe-57 Mössbauer spectrum of coated sample showed the presence a quadrupole doublet with a splitting of 0.46 mm/s, which is typical of Al-rich iron compounds. MOKE study shows an in-plane magnetic moment.

  2. Cratering Studies in Thin Plastic Films

    NASA Astrophysics Data System (ADS)

    Shu, A. J.; Bugiel, S.; Gruen, E.; Horanyi, M.; Munsat, T. L.; Srama, R.

    2014-12-01

    Thin plastic films, such as Polyvinylidene Fluoride (PVDF), have been used as protective coatings or dust detectors on a number of missions including the Dust Counter and Mass Analyzer (DUCMA) instrument on Vega 1 and 2, the High Rate Detector (HRD) on the Cassini Mission, and the Student Dust Counter (SDC) on New Horizons. These types of detectors can be used on the lunar surface or in lunar orbit to detect dust grain size distributions and velocities. Due to their low power requirements and light weight, large surface area detectors can be built for observing low dust fluxes. The SDC dust detector is made up of a permanently polarized layer of PVDF coated on both sides with a thin layer (≈ 1000 Å) of aluminum nickel. The operation principle is that a micrometeorite impact removes a portion of the metal surface layer exposing the permanently polarized PVDF underneath. This causes a local potential near the crater changing the surface charge of the metal layer. The dimensions and shape of the crater determine the strength of the potential and thus the signal generated by the PVDF. The theoretical basis for signal interpretation uses a crater diameter scaling law which was not intended for use with PVDF. In this work, a crater size scaling law has been experimentally determined, and further simulation work is being done to enhance our understanding of the mechanisms of crater formation. LS-Dyna, a smoothed particle hydrodynamics (SPH) code from the Livermore Software Technology Corp. was chosen to simulate micrometeorite impacts. It is capable of incorporating key physics phenomena, including fracture, heat transfer, melting, etc. Furthermore, unlike Eulerian methods, SPH is gridless allowing large deformities without the inclusion of unphysical erosion algorithms. Material properties are accounted for using the Grüneisen Equation of State. The results of the SPH model can then be fed into electrostatic relaxation models to enhance the fidelity of interpretation

  3. Cratering Studies in Thin Plastic Films

    NASA Astrophysics Data System (ADS)

    Shu, A. J.; Bugiel, S.; Gruen, E.; Hillier, J.; Horanyi, M.; Munsat, T. L.; Srama, R.

    2013-12-01

    Thin plastic films, such as Polyvinylidene Fluoride (PVDF), have been used as protective coatings or dust detectors on a number of missions including the Dust Counter and Mass Analyzer (DUCMA) instrument on Vega 1 and 2, the High Rate Detector (HRD) on the Cassini Mission, and the Student Dust Counter (SDC) on New Horizons. These types of detectors can be used on the lunar surface or in lunar orbit to detect dust grain size distributions and velocities. Due to their low power requirements and light weight, large surface area detectors can be built for observing low dust fluxes. The SDC dust detector is made up of a permanently polarized layer of PVDF coated on both sides with a thin layer (≈ 1000 Å) of aluminum nickel. The operation principle is that a micrometeorite impact removes a portion of the metal surface layer exposing the permanently polarized PVDF underneath. This causes a local potential near the crater changing the surface charge of the metal layer. The dimensions and shape of the crater determine the strength of the potential and thus the signal generated by the PVDF. The theoretical basis for signal interpretation uses a crater diameter scaling law which was not intended for use with PVDF. In this work, a crater size scaling law has been experimentally determined, and further simulation work is being done to enhance our understanding of the mechanisms of crater formation. LS-Dyna, a smoothed particle hydrodynamics (SPH) code from the Livermore Software Technology Corp. was chosen to simulate micrometeorite impacts. SPH is known to be well suited to the large deformities found in hypervelocity impacts. It is capable of incorporating key physics phenomena, including fracture, heat transfer, melting, etc. Furthermore, unlike Eulerian methods, SPH is gridless allowing large deformities without the inclusion of unphysical erosion algorithms. Material properties are accounted for using the Grüneisen Equation of State. The results of the SPH model can

  4. Photoemission Spectroscopic Study of Cesium Telluride Thin Film Photocathode

    SciTech Connect

    Sugiyama, Harue; Ogawa, Koji; Azuma, Junpei; Takahashi, Kazutoshi; Kamada, Masao

    2009-08-04

    The photoemission spectroscopy using synchrotron radiation has been carried out to study the high quantum efficiency and long working lifetime of cesium telluride (Cs{sub x}Te{sub y}) thin film photocathode. The electron affinity derived from the observed energy-distribution curves provides an important hint for long persistency of the photocathode.

  5. Radiochromic films for dental CT dosimetry: a feasibility study.

    PubMed

    Rampado, O; Bianchi, S D; Peruzzo Cornetto, A; Rossetti, V; Ropolo, R

    2014-02-01

    Dental CT dose evaluations are commonly performed using thermoluminescent dosimeters (TLD) inside anthropomorphic phantoms. Radiochromic films with good sensitivity in the X-ray diagnostic field have recently been developed and are commercially available as GAFCHROMIC XR-QA. There are potential advantages in the use of radiochromic films such as a more comprehensive dosimetry thanks to the adjustable size of the film samples. The purpose of this study was to investigate the feasibility of using radiochromic films for dental CT dose evaluations. Film samples were cut with a width of 5mm and a length of 25 mm (strips), the same size as the Alderson Rando anthropomorphic phantom holes used in this study. Dental CT dose measurements were performed using simultaneously both TLD and radiochromic strips in the same phantom sites. Two equipment types were considered for dental CT examinations: a 16 slice CT and a cone beam CT. Organ equivalent doses were then obtained averaging the measurements from the sites of the same organ and effective doses were calculated using ICRP 103 weighting factors. The entire procedure was repeated four times for each CT in order to compare also the repeatability of the two dosimeter types. A linear correlation was found between the absorbed dose evaluated with radiochromic films and with TLD, with slopes of 0.930 and 0.944 (correlation r>0.99). The maximum difference between the two dosimeter's measurements was 25%, whereas the average difference was 7%. The measurement repeatability was comparable for the two dosimeters at cumulative doses above 15 mGy (estimated uncertainty at 1 sigma level of about 5%), whereas below this threshold radiochromic films show a greater dispersion of data, of about 10% at 1 sigma level. We obtained, using respectively Gafchromic and TLD measurements, effective dose values of 107 μSv and 117 μSv (i.e. difference of 8.6%) for the cone beam CT and of 523 μSv and 562 μSv (i.e. difference of 7%) for the

  6. Nanocrystalline zinc ferrite films studied by magneto-optical spectroscopy

    SciTech Connect

    Lišková-Jakubisová, E. Višňovský, Š.; Široký, P.; Hrabovský, D.; Pištora, J.; Sahoo, Subasa C.; Prasad, Shiva; Venkataramani, N.; Bohra, Murtaza; Krishnan, R.

    2015-05-07

    Ferrimagnetic Zn-ferrite (ZnFe{sub 2}O{sub 4}) films can be grown with the ferromagnetic resonance linewidth of 40 Oe at 9.5 GHz without going through a high temperature processing. This presents interest for applications. The work deals with laser ablated ZnFe{sub 2}O{sub 4} films deposited at O{sub 2} pressure of 0.16 mbar onto fused quartz substrates. The films about 120 nm thick are nanocrystalline and their spontaneous magnetization, 4πM{sub s}, depends on the nanograin size, which is controlled by the substrate temperature (T{sub s}). At T{sub s} ≈ 350 °C, where the grain distribution peaks around ∼20–30 nm, the room temperature 4πM{sub s} reaches a maximum of ∼2.3 kG. The films were studied by magnetooptical polar Kerr effect (MOKE) spectroscopy at photon energies between 1 and 5 eV. The complementary characteristics were provided by spectral ellipsometry (SE). Both the SE and MOKE spectra confirmed ferrimagnetic ordering. The structural details correspond to those observed in MgFe{sub 2}O{sub 4} and Li{sub 0.5}Fe{sub 2.5}O{sub 4} spinels. SE experiments confirm the insulator behavior. The films display MOKE amplitudes somewhat reduced with respect to those in Li{sub 0.5}Fe{sub 2.5}O{sub 4} and MgFe{sub 2}O{sub 4} due to a lower degree of spinel inversion and nanocrystalline structure. The results indicate that the films are free of oxygen vacancies and Fe{sup 3+}-Fe{sup 2+} exchange.

  7. A Controlled Study on the Correlation between Tear Film Volume and Tear Film Stability in Diabetic Patients

    PubMed Central

    Khalil, Noha M.; El-Gendy, Heba A.

    2016-01-01

    Purpose. To assess the tear film quantity and correlate it with the quality and stability of the tear film in diabetics and compare them to age matched controls. Introduction. Diabetes affects tear film parameters in multiple ways. Poor metabolic control and neuropathy are postulated factors. To further understand how diabetes affects tear film parameters this study was conducted. Subjects and Methods. Tear meniscus height was measured by anterior segment OCT, along with tear thinning time, a subtype of noninvasive tear break-up time, and blinking rate per minute which were all recorded for 22 diabetic patients. Correlations between these tear film parameters were studied and then compared to 16 age matched controls. Results. A statistically significant difference was found in blinking rate between the diabetic and the control group (P = 0.002), with higher blinking rate among diabetics. All tear film parameters were negatively correlated with duration of diabetes. A positive correlation was found between tear film volume and stability. Conclusion. Diabetes affects the tear film in various ways. Diabetics should be examined for dry eye signs even in absence of symptoms which may be masked by associated neuropathy. Duration of diabetes has an impact on tear film status. PMID:27034823

  8. Experimental study of graphitic nanoribbon films for ammonia sensing

    NASA Astrophysics Data System (ADS)

    Johnson, Jason L.; Behnam, Ashkan; An, Yanbin; Pearton, S. J.; Ural, Ant

    2011-06-01

    We fabricate and study the ammonia sensing properties of graphitic nanoribbon films consisting of multi-layer graphene nanoribbons. These films show very good sensitivity to parts-per-million (ppm) level concentrations of ammonia, which is further enhanced by platinum functionalization, resulting in a relative resistance response of ˜70% when exposed to 50 ppm ammonia. In addition, the sensing response exhibits excellent repeatability and full recovery in air. We also study in detail the dependence of the sensing response on ammonia concentration and temperature. We find that the relative resistance response of the graphitic nanoribbon films shows a power-law dependence on the ammonia concentration, which can be explained based on the Freundlich isotherm. The activation energy obtained from an Arrhenius plot of the temperature-dependent measurements is ˜50 meV, which is consistent with the theoretical calculations of the adsorption energies of ammonia on large graphene sheets and nanoribbons. Their simple and low-cost fabrication process and good sensing response open up the possibility of using graphitic nanoribbon films for large-scale sensing applications.

  9. Bulk and thin films of FeTe: A Moessbauer study

    NASA Technical Reports Server (NTRS)

    Escue, W. T.; Aggarwal, K.; Mendiratta, R. G.

    1977-01-01

    Studies of bulk and thin films of FeTe using Moessbauer spectroscopy showed that FeTe has one noncubic Fe (+2) site which is 3d2 4s 4p3 hybridized. The presence of dangling bands was indicated in spectra of FeTe thin films. The films showed a tendency of texture formation. The substrate was observed to influence the film structure and nature of bonds in films.

  10. Discrete component bonding and thick film materials study

    NASA Technical Reports Server (NTRS)

    Kinser, D. L.

    1975-01-01

    The results are summarized of an investigation of discrete component bonding reliability and a fundamental study of new thick film resistor materials. The component bonding study examined several types of solder bonded components with some processing variable studies to determine their influence upon bonding reliability. The bonding reliability was assessed using the thermal cycle: 15 minutes at room temperature, 15 minutes at +125 C 15 minutes at room temperature, and 15 minutes at -55 C. The thick film resistor materials examined were of the transition metal oxide-phosphate glass family with several elemental metal additions of the same transition metal. These studies were conducted by preparing a paste of the subject composition, printing, drying, and firing using both air and reducing atmospheres. The resulting resistors were examined for adherence, resistance, thermal coefficient of resistance, and voltage coefficient of resistance.

  11. Structural, Magnetic and Spectroscopic Studies of Thin Manganite Films

    NASA Astrophysics Data System (ADS)

    Tyson, T. A.

    2003-03-01

    Starting from early experiments [1], evidence has been found for a close coupling of strain and the magnetotransport properties of manganite films. The characteristic feature found is that the metal to insulator transition temperature (TMI) is suppressed in very thin films [2]. In addition, studies show that the magnetic transition temperature (Tc) and TMI decouple in ultrathin films [3]. Systematic magnetization studies reveal that strain induces strong magnetic anisotropy [4]. Theoretical work also points to the sensitivity of Tc to biaxial strain [5]. Most studies have focused on single bulk properties. In order to understand the correlations between strain and the transport and magnetic properties we have examined the structure of films on multiple length scales. The local structure of films have been studies by x-ray absorption spectroscopy. The long -range structure has been studied by high-resolution x-ray diffraction and the microstructure has been studied by AFM measurements. These measurements are correlated with bulk magnetization and transport studies. Insight is gained on the evolution of lattice strain and Jahn-Teller distortions with thickness. Direct evidence is found for the arrest of charge ordering with strain and the existence of strain induced insulating regions of films. The magnetic ordering and transport properties as a function of strain as compared with bandstructure calculations. This work is supported by NSF Career Grant DMR-9733862 and DMR-0209243. Collaborators: Q. Qian, M. Deleon (NJIT), C. Dubourdiu (CNRS), J. Bai (ORNL), W. Prellier, A. Biswas, R. L. Greene (U. Maryland) [1] S. Jin et al., Appl. Phys. Lett. 67, 557 (1995). [2] (a) J. Z. Sun et al. Appl. Phys. Lett. 74, 3017 (1999). (b) F. S. Razi et al., Appl. Phys. Lett 76, 155 (2000) [3] J. Aarts et al., Appl. Phys. Lett. 72, 2975 (1998). (b) R. A. Rao et al., J. Appl. Phys. 85, 4794 (1999). [4] (a) X. W. Wu et al., Phys. Rev. B 61, 501 (2000). (b) J. O'Donnell et al., Appl. Phys

  12. FMR study of thin film FeGe skyrmionic material

    NASA Astrophysics Data System (ADS)

    Bhallamudi, Vidya P.; Page, Michael R.; Gallagher, James; Purser, Carola; Schulze, Joseph; Yang, Fengyuan; Hammel, P. Chris

    Magnetic Skyrmions have attracted intense interest due to their novel topological properties and the potential for energy efficient computing. Magnetic dynamics play an important part in enabling some of these functionalities. Understanding these dynamics can shed light on the interplay of the various magnetic interactions that exist in these materials and lead to a rich magnetic phase diagram, including the Skyrmion phase. We have grown phase-pure FeGe epitaxial films on Si (111) and studied them using ferromagnetic resonance (FMR). FeGe has one of the highest recorded skyrmion transition temperatures, close to room temperature, and thin films are known to further stabilize the Skyrmion phase in the magnetic field-temperature space. We have performed cavity-based single frequency FMR from liquid nitrogen to room temperature on 120 nm thick films in both in-plane and out-of-plane geometries. The resulting complex spectra are consistent with those reported in literature for the bulk material and can be understood in terms of a conical model for the magnetism. Variable temperature broadband spectroscopy and measurements on thinner films, to better identify the various magnetic phases and their dynamic behavior, are ongoing and their progress will be discussed. Funding for this research was provided by the Center for Emergent Materials: an NSF MRSEC under Award Number DMR-1420451.

  13. Ellipsometric study of oxide films formed on LDEF metal samples

    NASA Technical Reports Server (NTRS)

    Franzen, W.; Brodkin, J. S.; Sengupta, L. C.; Sagalyn, P. L.

    1992-01-01

    The optical constants of samples of six different metals (Al, Cu, Ni, Ta, W, and Zr) exposed to space on the Long Duration Exposure Facility (LDEF) were studied by variable angle spectroscopic ellipsometry. Measurements were also carried out on portions of each sample which were shielded from direct exposure by a metal bar. A least-squares fit of the data using an effective medium approximation was then carried out, with thickness and composition of surface films formed on the metal substrates as variable parameters. The analysis revealed that exposed portions of the Cu, Ni, Ta, and Zr samples are covered with porous oxide films ranging in thickness from 500 to 1000 A. The 410 A thick film of Al2O3 on the exposed Al sample is practically free of voids. Except for Cu, the shielded portions of these metals are covered by thin non-porous oxide films characteristic of exposure to air. The shielded part of the Cu sample has a much thicker porous coating of Cu2O. The tungsten data could not be analyzed.

  14. Extension of Radiochromic Film Dosimetry to Three Dimensions: A Feasibility Study

    SciTech Connect

    Adamczyk, S.; Skorska, M.

    2007-11-26

    The feasibility of measuring dose distributions in three-dimensions using Gafchromic EBT film was studied. A stack of film was used as tomographic dosimeter. The response of film (4x4 cm{sup 2}) placed between a stack of Gafchromic EBT films and slabs of polystyrene phantom was tested. Differences in film response for two different photon beam qualities, 6 MV and 25 MV, were observed. Measurements with 6 MV beam quality revealed that for different field sizes and depths there were no changes in response of EBT Gafchromic film when placed between polystyrene plates or sandwiched between other films. However, in the case of 25 MV beam quality, a statistically significant over-response was found for film placed in stack. We conclude that stacked-film dosimetry is feasible at 6 MV. For 25 MV photon beam quality the stack of films showed different properties than the polystyrene slabs of the same height.

  15. A study of Ag/Ag(100) thin film growth with scanning tunneling microscopy

    SciTech Connect

    Wen, J.

    1995-11-01

    Thin films are attracting more and more attention in both the industrial and scientific communities. Many applications of thin films have been developed in industry. By using various growth methods, thin films can be used in optics, microelectronic devices, magnetic recording media, and as protective coatings. In order to improve existing applications and to find new ones, it is essential to understand what makes them so useful in applications and what factors affect their properties. Therefore, an understanding of film growth processes is necessary. Scientifically, many fundamental interactions, such as the interaction between the atoms that comprise the film and substrate, or the interaction between film atoms, are of great interest to surface scientists; studies of these interactions can provide dramatic insights into the nature of thin films and therefore, can further drive technology forward. In every application, the film structures, including morphology and microstructure, and adhesion between film and substrate are critical to the film`s properties and therefore its performance. Studies of the mechanisms that control film morphology, microstructure and adhesion thus are important. Film growth kinetics can provide important information regarding the film structure and adhesion. Film growth is an atomistic process. The chemistry and physics of the system can be better understood if the information provided is at an atomic level.

  16. Using Systemic Functional Linguistics in Academic Writing Development: An Example from Film Studies

    ERIC Educational Resources Information Center

    Donohue, James P.

    2012-01-01

    On film studies courses, students are asked to treat as objects of study the same films which they may more commonly experience as entertainment. To explore the role of academic writing in this, an action research project was carried out on a university film studies course using a systemic functional linguistics approach. This paper presents a key…

  17. Studies on nickel-tungsten oxide thin films

    SciTech Connect

    Usha, K. S.; Sivakumar, R.; Sanjeeviraja, C.

    2014-10-15

    Nickel-Tungsten oxide (95:5) thin films were prepared by rf sputtering at 200W rf power with various substrate temperatures. X-ray diffraction study reveals the amorphous nature of films. The substrate temperature induced decrease in energy band gap with a maximum transmittance of 71%1 was observed. The Micro-Raman study shows broad peaks at 560 cm{sup −1} and 1100 cm{sup −1} correspond to Ni-O vibration and the peak at 860 cm{sup −1} can be assigned to the vibration of W-O-W bond. Photoluminescence spectra show two peaks centered on 420 nm and 485 nm corresponding to the band edge emission and vacancies created due to the addition of tungsten, respectively.

  18. Studies on nickel-tungsten oxide thin films

    NASA Astrophysics Data System (ADS)

    Usha, K. S.; Sivakumar, R.; Sanjeeviraja, C.

    2014-10-01

    Nickel-Tungsten oxide (95:5) thin films were prepared by rf sputtering at 200W rf power with various substrate temperatures. X-ray diffraction study reveals the amorphous nature of films. The substrate temperature induced decrease in energy band gap with a maximum transmittance of 71%1 was observed. The Micro-Raman study shows broad peaks at 560 cm-1 and 1100 cm-1 correspond to Ni-O vibration and the peak at 860 cm-1 can be assigned to the vibration of W-O-W bond. Photoluminescence spectra show two peaks centered on 420 nm and 485 nm corresponding to the band edge emission and vacancies created due to the addition of tungsten, respectively.

  19. Partial discharge degradation and breakdown studies in polypropylene films

    SciTech Connect

    Thomas, B.; Nema, R.S.

    1996-12-31

    Internal partial discharge characteristics are investigated on impregnated polypropylene films containing artificial cavity of well-defined dimensions, immersed in oil. Electrical breakdown studies are carried out at step-wise rising stress to evaluate constants of inverse power law model. Partial discharge pulse distribution patterns are acquired using PC interfaced multichannel analyzer and statistical analysis of the discharge pulse spectrum is done by using 3-parameter Weibull distribution function. The results are compared with that for unimpregnated samples in air.

  20. Feasibility study of the separation of chlorinated films from plastic packaging wastes

    SciTech Connect

    Reddy, Mallampati Srinivasa; Yamaguchi, Takefumi; Okuda, Tetsuji; Tsai, Tsung-Yueh; Nakai, Satoshi; Nishijima, Wataru; Okada, Mitsumasa

    2010-04-15

    This study describes the possible separation of chlorinated plastic films (PVC and PVDC) from other heavy plastic packaging waste (PPW) by selective twist formation and gravity separation. Twists formation was mechanically induced in chlorinated plastic films, whereas twist formation did not occur in PS and PET films. After twist formation, all the films had the apparent density of less than 1.0 g/cm{sup 3} and floated in water even though the true density was more than 1.0 g/cm{sup 3}. However, the apparent density of the PS and the PET films increased with agitation to more than 1.0 g/cm{sup 3}, whereas that of chlorinated plastic films was kept less than 1.0 g/cm{sup 3}. The main reason would be the air being held inside the chlorinated plastic films which was difficult to be removed by agitation. Simple gravity separation after twist formation was applied for artificial film with 10 wt.% of the chlorinated films and real PPW films with 9 wt.% of the chlorinated films. About 76 wt.% of the artificial PPW films and 75 wt.% of real PPW films after the removal of PP and PE were recovered as settling fraction with 4.7 wt.% and 3.0 wt.% of chlorinated plastic films, respectively. These results indicate that simple gravity separation process after twist formation can be used to reduce the chlorinated plastic concentration from mixed heavy PPW films.

  1. [Comparative study of very high speed dental films].

    PubMed

    Benz, C

    1989-09-01

    Two new periapical films (Agfa Dentus M 4, Dupont Super Dozahn HS) were evaluated in comparison to Kodak-Ultraspeed and -Ektaspeed films. Dentus M 4 proved to be the fastest film available. Though higher sensitivity results in less contrast, faster films can in most cases be used with the advantage of maximal dose reduction. PMID:2637857

  2. Analytical study of pressure balancing in gas film seals.

    NASA Technical Reports Server (NTRS)

    Zuk, J.

    1973-01-01

    Proper pressure balancing of gas film seals requires knowledge of the pressure profile load factor (load factor) values for a given set of design conditions. In this study, the load factor is investigated for subsonic and choked flow conditions, laminar and turbulent flows, and various seal entrance conditions. Both parallel sealing surfaces and surfaces with small linear deformation were investigated. The load factor for subsonic flow depends strongly on pressure ratio; under choked flow conditions, however, the load factor is found to depend more strongly on film thickness and flow entrance conditions rather than pressure ratio. The importance of generating hydrodynamic forces to keep the seal balanced under severe and multipoint operation is also discussed.

  3. Aging studies on thin tetra-phenyl butadiene films

    NASA Astrophysics Data System (ADS)

    Acciarri, R.; Canci, N.; Cavanna, F.; Segreto, E.; Szelc, A. M.

    2013-10-01

    Tetra-Phenyl Butadiene (TPB) is the most commonly used compound to wave-shift the 128 nm scintillation light of liquid Argon down to the visible spectrum. We present a study on the loss of conversion efficiency of thin TPB films evaporated on reflective foils when exposed to light and atmosphere. The efficiency of the films is measured and monitored with a dedicated set-up that uses gaseous Argon excited by alpha particles to produce 128 nm photons and working at room temperature. In particular we performed a two years long exposure of the samples to lab diffuse light and atmosphere. We also performed more controlled aging tests to investigate the effect of storing samples in a inert atmosphere.

  4. Bauschinger effect in thin metal films: Discrete dislocation dynamics study

    NASA Astrophysics Data System (ADS)

    Davoudi, Kamyar M.; Nicola, Lucia; Vlassak, Joost J.

    2014-01-01

    The effects of dislocation climb on plastic deformation during loading and unloading are studied using a two-dimensional discrete dislocation dynamics model. Simulations are performed for polycrystalline thin films passivated on both surfaces. Dislocation climb lowers the overall level of the stress inside thin films and reduces the work hardening rate. Climb decreases the density of dislocations in pile-ups and reduces back stresses. These factors result in a smaller Bauschinger effect on unloading compared to simulations without climb. As dislocations continue to climb at the onset of unloading and the dislocation density continues to increase, the initial unloading slope increases with decreasing unloading rate. Because climb disperses dislocations, fewer dislocations are annihilated during unloading, leading to a higher dislocation density at the end of the unloading step.

  5. Combinatorial study of zinc tin oxide thin-film transistors

    SciTech Connect

    McDowell, M. G.; Sanderson, R. J.; Hill, I. G.

    2008-01-07

    Groups of thin-film transistors using a zinc tin oxide semiconductor layer have been fabricated via a combinatorial rf sputtering technique. The ZnO:SnO{sub 2} ratio of the film varies as a function of position on the sample, from pure ZnO to SnO{sub 2}, allowing for a study of zinc tin oxide transistor performance as a function of channel stoichiometry. The devices were found to have mobilities ranging from 2 to 12 cm{sup 2}/V s, with two peaks in mobility in devices at ZnO fractions of 0.80{+-}0.03 and 0.25{+-}0.05, and on/off ratios as high as 10{sup 7}. Transistors composed predominantly of SnO{sub 2} were found to exhibit light sensitivity which affected both the on/off ratios and threshold voltages of these devices.

  6. Langmuir films study on lipid-containing artificial tears.

    PubMed

    Torrent-Burgués, J

    2016-04-01

    Lipid-containing artificial tears are a type of artificial tears that use lipid components in order to restore the lipid layer of the tear film. One of these components is lecithin which can be applied in spray solutions containing lecithin liposomes. In this work the behavior of three of these commercial tears based on lecithin, Innoxa, Opticalm and Optrex, are studied using the Langmuir technique. The obtained isotherms are presented, discussed and compared. This technique seems useful in order to see the film behavior of the lipid components of these tears and determine some important parameters such as fluidity and extension at the air-water interface, and allows us to discern differences between these commercial tears. Innoxa and Optrex tears are more similar to each other than to Opticalm tears. Opticalm presents more fluidity, probably due to the presence of more insaturations in the fatty acid chains of the phospholipids of the lecithin used in fabrication. PMID:26764100

  7. Radio, Television and Film: The State of Study in the 1980s.

    ERIC Educational Resources Information Center

    Gomery, Douglas

    1985-01-01

    Analyzes two influential basic textbooks in the study of radio-television-film (RTVF): "Broadcasting in America" and "Film Art: An Introduction." Comments on how the RTVF organization impacts graduate education. (PD)

  8. Nanomechanical study of thin film nanocomposite and PVD thin films on polymer substrates for optical applications

    NASA Astrophysics Data System (ADS)

    Moghal, Jonathan; Bird, Andrew; Harris, Adrian H.; Beake, Ben D.; Gardener, Martin; Wakefield, Gareth

    2013-12-01

    The mechanical properties of ultrathin (<120 nm) films differ substantially from the bulk properties of the material and are also strongly substrate dependent. We compare the properties of two differing film systems; a high particle loading nanocomposite of silica and a multiple layer physical vapour deposition (PVD) coating by nanoindentation, nano-scratch and nano-impact followed by structural analysis. The work is undertaken on hardcoated polymer substrates and uses two types of anti-reflection coatings as test systems. The nanocomposite film comprises of a high (>50%) loading of silica nanoparticles in an inorganic binder, which demonstrates significant flex and elastic recovery whereas PVD films are subject to brittle failure even at low applied loads. Failure of the nanocomposite film, with the exception of minor plastic deformation, does not occur until the underlying substrate fails. Although the PVD film has a greater hardness than the nanocomposite, failure occurs at lower loads due to a number of toughness reducing factors including reduced modulus, modulus mismatch with the substrate and film thickness. The resistance of ultrathin films to external mechanical stresses is therefore related to a number of factors and not simply to film hardness, the most important of which are film structure and film mechanical matching to the substrate.

  9. A pilot study on the quality control of film processing in medical radiology laboratories in Greece.

    PubMed

    Hourdakis CJ-; Delakis, J; Kamenopoulou, V; Balougias, H; Papageorgiou, E

    2000-01-01

    The results of a pilot study on the quality of film processing in 80 medical diagnostic radiology laboratories all over Greece are presented. The sensitometric technique for the evaluation of processing has been used to calculate film's base + fog, maximum optical density, speed and contrast, parameters which describe the performance characteristics of automatic film processors and films. The mean values of the base + fog and the maximum optical density were well within the acceptance limits. The film speed was almost constant while the film contrast showed significant variation. PMID:10674786

  10. Thermodynamic study of argon films adsorbed on boron nitride

    SciTech Connect

    Migone, A.D.; Alkhafaji, M.T. ); Vidali, G. ); Karimi, M. )

    1993-03-15

    We have performed a detailed adsorption isotherm study of Ar on BN for temperatures between 65 and 80 K. The isothermal compressibility of the films was obtained from adsorption data. At monolayer coverages, a small isotherm substep is present at melting. We found two isothermal compressibility peaks in the first layer: a sharp peak, corresponding to the melting substep, and a smaller, broader peak that occurs at lower pressures. At multilayer coverages we found reentrant layering occurring in the third and fourth layers of the film. We compare our layering results with predictions for the preroughening transition. We also found a series of small steps in the isotherms between the second and third layers and between the third and fourth layers of the film. These small steps are evidence of individual layer melting for the second and third layers. Our results at monolayer and at multilayer coverages are extensively compared to those found for Ar on graphite. We have also performed calculations of the rare-gas--BN interaction potentials. Our calculations indicate the substrate corrugation is smaller for the rare-gas--BN systems than it is for the same rare gases on graphite. The implications of this result for the possible existence of monolayer-commensurate solids on BN are discussed.

  11. Spin polarized photoemission studies of interfacial and thin film magnetism

    SciTech Connect

    Johnson, P.D.; Brookes, N.B.; Chang, Y.; Garrison, K.

    1993-01-01

    Spin polarized photoemission is used to study the electronic structure of noble metals deposited on ferromagnetic substrates. Studies of Ag deposited on an Fe(001) substrate reveal a series of minority spin interface or quantum well states with binding energies dependent on the thickness of the silver. Similar behavior is observed for Cu films deposited on a fct Co(001) substrate. Tight-binding modeling reproduces many of the observations and shows that hybridization of the sp-bands with the noble metal d-bands cannot be ignored.

  12. Spin polarized photoemission studies of interfacial and thin film magnetism

    SciTech Connect

    Johnson, P.D.; Brookes, N.B.; Chang, Y.; Garrison, K.

    1993-06-01

    Spin polarized photoemission is used to study the electronic structure of noble metals deposited on ferromagnetic substrates. Studies of Ag deposited on an Fe(001) substrate reveal a series of minority spin interface or quantum well states with binding energies dependent on the thickness of the silver. Similar behavior is observed for Cu films deposited on a fct Co(001) substrate. Tight-binding modeling reproduces many of the observations and shows that hybridization of the sp-bands with the noble metal d-bands cannot be ignored.

  13. NMR Studies of 3He Films on Boron Nitride

    NASA Astrophysics Data System (ADS)

    Tang, Y.; Sullivan, N. S.

    2014-12-01

    We report the results of NMR studies of the dynamics of 3He adsorbed on hexagonal boron nitride. These studies can identify the phase transitions of the 2D films as a function of temperature. A thermally activated temperature dependence is observed for 2.6 < T < 8 K compared to a linear temperature dependence for 0.7 < T < 2.6 K. This linear dependence is consistent with that expected for thermal diffusion in a fluid for coverages of 0.4 - 0.6 of a monolayer.

  14. Motion Pictures for the Study of India: A Guide to Classroom Films.

    ERIC Educational Resources Information Center

    Vestal, Theodore M.

    After a three year review of films on India available in the United States, the Resource Center offered this guide to those motion pictures adjudged best for use in American classrooms. There are twelve documentary films and four commercial feature films included for use at any level of school, college, or university study: Child of the Streets; A…

  15. Fostering Historical Thinking toward Civil Rights Movement Counter-Narratives: Documentary Film in Elementary Social Studies

    ERIC Educational Resources Information Center

    Buchanan, Lisa Brown

    2015-01-01

    This article describes how elementary preservice teachers used four documentary films to think historically about the United States Civil Rights Movement. The author situates the descriptive case study within research about historical thinking and documentary film, identifying the need for using documentary film to think historically in the…

  16. Moessbauer study in thin films of FeSi2 and FeSe systems

    NASA Technical Reports Server (NTRS)

    Escue, W. J.; Aggarwal, K.; Mendiratta, R. G.

    1978-01-01

    Thin films of FeSi2 and FeSe were studied using Moessbauer spectroscopy information regarding dangling bond configuration and nature of crystal structure in thin films was derived. A significant influence of crystalline aluminum substrate on film structure was observed.

  17. Optimization study of the femtosecond laser-induced forward-transfer process with thin aluminum films

    NASA Astrophysics Data System (ADS)

    Bera, Sudipta; Sabbah, A. J.; Yarbrough, J. M.; Allen, C. G.; Winters, Beau; Durfee, Charles G.; Squier, Jeff A.

    2007-07-01

    The parameters for an effective laser-induced forward-transfer (LIFT) process of aluminum thin films using a femtosecond laser are studied. Deposited feature size as a function of laser fluence, donor film thickness, quality of focus, and the pulse duration are varied, providing a metric of the most desirable conditions for femtosecond LIFT with thin aluminum films.

  18. Scanning Tunneling Microscopy Studies of Diamond Films and Optoelectronic Materials

    NASA Technical Reports Server (NTRS)

    Perez, Jose M.

    1996-01-01

    We present a summary of the research, citations of publications resulting from the research and abstracts of such publications. We have made no inventions in the performance of the work in this project. The main goals of the project were to set up a Chemical Vapor Deposition (CVD) diamond growth system attached to an UltraHigh Vacuum (UHV) atomic resolution Scanning Tunneling Microscopy (STM) system and carry out experiments aimed at studying the properties and growth of diamond films using atomic resolution UHV STM. We successfully achieved these goals. We observed, for the first time, the atomic structure of the surface of CVD grown epitaxial diamond (100) films using UHV STM. We studied the effects of atomic hydrogen on the CVD diamond growth process. We studied the electronic properties of the diamond (100) (2x1) surface, and the effect of alkali metal adsorbates such as Cs on the work function of this surface using UHV STM spectroscopy techniques. We also studied, using STM, new electronic materials such as carbon nanotubes and gold nanostructures. This work resulted in four publications in refereed scientific journals and five publications in refereed conference proceedings.

  19. FMR study of Co-substituted yttrium iron garnet films

    NASA Astrophysics Data System (ADS)

    Jabłoński, R.; Maziewski, A.; Tekielak, M.; Desvignes, J. M.

    1996-07-01

    Ferromagnetic resonance has been studied in Y 3- zCa zFe 5- x-yCo xGe yO 12 films grown on the (001) plane of a GGG substrate. Temperature-induced spin-reorientation phase transitions were observed. On cooling the sample, the easy magnetization axes orientations changed from directions near [111] to [100], and the [001] direction had the lowest energy. The FMR signal was practically non-measurable below 60 and 120 K when the magnetic field was applied along the [110] and [100] axes, respectively.

  20. Polarized micro-Raman spectroscopy study of pentacene thin films

    NASA Astrophysics Data System (ADS)

    Stenger, Ingrid; Frigout, Alexandre; Tondelier, Denis; Geffroy, Bernard; Ossikovski, Razvigor; Bonnassieux, Yvan

    2009-03-01

    We report on polarized micro-Raman spectroscopy study of two pentacene thin films exhibiting different microstructures: a well-ordered sample and a more disordered one. We have investigated the frequency range of the intramolecular C-H bending modes in the plane of the pentacene molecule and proposed an interpretation of the Raman spectra. The use of symmetry properties of the two intramolecular (uncoupled) modes allowed us to unambiguously identify it among the five main contributions observed in this spectral range. The three other modes were assumed to be resulting from molecular coupling effect owing to their different behavior upon the samples microstructure.

  1. Structural and magnetic studies of Cr doped nickel ferrite thin films

    NASA Astrophysics Data System (ADS)

    Panwar, Kalpana; Heda, N. L.; Tiwari, Shailja; Bapna, Komal; Choudhary, R. J.; Phase, D. M.; Ahuja, B. L.

    2016-05-01

    We have studied the structural and magnetic properties of Cr doped nickel ferrite thin films deposited on Si (100) and Si (111) using pulsed laser deposition technique. The films were deposited under vacuum and substrate temperature was kept at 700˚C. X-ray diffraction analysis revealed that films on both substrates have single phase cubic spinel structure. However, the film grown on Si (111) shows better crystalline behavior. Fourier transform infrared spectroscopy suggests that films on both substrates have mixed spinel structure. These films show magnetic hysteresis behavior and magnetization value of film on Si (100) is larger than that on Si (111). It turns out that structural and magnetic properties of these two films are correlated.

  2. Design of hybrid sol gel films for direct x-ray and electron beam nanopatterning

    NASA Astrophysics Data System (ADS)

    Brusatin, Giovanna; Della Giustina, Gioia; Romanato, Filippo; Guglielmi, Massimo

    2008-04-01

    New epoxy based sol-gel organic inorganic materials, showing lithographic resist-like properties without the addition of any photocatalysts, are presented. To obtain a material sensitive to radiation, specific sol-gel syntheses based on an organically modified alkoxide containing an epoxy ring, 3-glycidoxypropyltrimethoxysilane (GPTMS), have been developed. The synthesis and the patternability of hybrid materials have been obtained controlling the inorganic crosslinking degree and with an almost total absence of organic polymerization. Two examples of directly patternable hybrid films, called GB and GGe, have been synthesized using acidic (GGe) and basic (GB) conditions and obtaining different compositions. After electron beam lithography (EBL) or x-ray synchrotron radiation lithography (XRL) the polymerization of the organic component of the sol-gel film occurs, generating a hardening of the structure after post-exposure baking. The exposed polymerized material becomes insoluble, determining a negative resist-like behaviour of the film: the lithographic process of nanopatterning results from the dissolution of the unexposed areas in proper solvents (developers). Spatial resolution of the order of 200 nm is reported and a contrast of 2.2 is achieved. The novelty of this work is that epoxy based materials, which have enhanced thermomechanical stability with respect to the more usual acrylic based resins, are directly nanopatterned for the first time by electron beam (EB) and/or x-ray beam radiation exposure without the aid of catalysts for polymerization. In contrast to common resists that are sacrificial layers of the fabrication process, direct patternable sol-gel hybrids constitute the final material of the devices. In fact, an example of doping with a light emitting dye is reported together with the achievement of directly patterned structures by EBL and XRL.

  3. Study of microstructure and electroluminescence of zinc sulfide thin film

    NASA Astrophysics Data System (ADS)

    Zhao-hong, Liu; Yu-jiang, Wang; Mou-zhi, Chen; Zhen-xiang, Chen; Shu-nong, Sun; Mei-chun, Huang

    1998-03-01

    The electroluminscent zinc sulfide thin film doped with erbium, fabricated by thermal evaporation with two boats, are examined. The surface and internal electronic states of ZnS thin film are measured by means of x-ray diffraction and x-ray photoemission spectroscopy. The information on the relations between electroluminescent characteristics and internal electronic states of the film is obtained. And the effects of the microstructure of thin film doped with rare earth erbium on electroluminescence are discussed as well.

  4. Studies of thin films of Ti- Zr -V as non-evaporable getter films prepared by RF sputtering

    SciTech Connect

    Gupta, Nidhi; Jagannath,; Sharma, R. K.; Gadkari, S. C.; Muthe, K. P.; Mukundhan, R.; Gupta, S. K.

    2013-02-05

    Non-Evaporable Getter (NEG) films of the Ti-Zr-V prepared on stainless steel substrates by Radio Frequency sputtering. To observe its getter behavior at the lowest activation temperature, the sample is heated continuously at different temperatures (100 Degree-Sign C, 150 Degree-Sign C, 200 Degree-Sign C and 250 Degree-Sign C) for 2 hours. The changes of the surface chemical composition at different temperaturesare analyzed by using XPS and SEM (Scanning Electron Microscopy) techniques. The volume elemental composition of the film has been measured by energy dispersive X-ray spectroscopy (EDX). The in-situ XPS measurements of the activated getter films show the disappearance of the superficial oxide layer through the variation in the oxygen stoichiometry during thermal activation. Results of these studies show that the deposited films of Ti-Zr-V could be used as NEG to produce extreme high vacuum.

  5. Spectroscopic studies of model polar stratospheric cloud films

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Koehler, Birgit G.; Middlebrook, Ann M.

    1993-01-01

    Fourier transform infrared (FTIR) spectroscopy has been used to study nitric-acid/ice films representative of type I polar stratospheric clouds (PSCs). These studies reveal that in addition to amorphous nitric acid/ice mixtures, there are three stable stoichiometric hydrates of nitric acid: nitric-acid monohydrate (NAM), dihydrate (NAD), and trihydrate (NAT). We also observe two distinct crystalline forms of the trihydrate, which we denote alpha- and beta-NAT. These two forms appear to differ in their concentration of crystalline defects, but not in their chemical composition. In addition to probing the composition of type I PSCs, we have also used FTIR spectroscopy to study the interaction of HCl with model PSC films. In this work we find that for HCl pressures in the range 10 exp -5 to 10 exp -7 Torr, HCl is taken up by ice at 155 K to form a thin layer of HCl.6H2O. At 193 K, the uptake of HCl by ice was consistent with less than or equal to monolayer coverage. Uptake of HCl by alpha and beta-NAT at 175 K was also consistent with less than or equal to monolayer coverage.

  6. Raman microprobe spectroscopic studies of solid DNA-CTMA films

    NASA Astrophysics Data System (ADS)

    Yaney, Perry P.; Ahmad, Faizan; Grote, James G.

    2008-08-01

    Extensive studies have been carried out on developing the new biopolymer, deoxyribonucleic acid (DNA) derived from salmon, that has been complexed with a surfactant to make it water insoluble for application to bioelectronic and biophotonic devices. One of the key issues associated with the properties and behavior of solid films of this material is the extreme size of the >8 MDa molecular weight of the virgin, as-received material. Reduction of this molecular weight by factors of up to 40 is achieved by high power sonication. To support the various measurements that have been made to confirm that the sonicated material is still double strand DNA and to look for other effects of sonication, Raman studies were carried out to compare the spectra over a wide range of molecular weights and to develop baseline data that can be used in intercolation studies where various dopants are added to change the electrical, mechanical or optical properties. Raman microprobe spectra from solid, dry thin films of DNA with molecular weights ranging from 200 kDa to >8 MDa complexed with cetyltrimethyl-ammonium chloride (CTMA) are reported and compared to the as-received spectrum and to published DNA spectra in aqueous solutions. In addition, microscopy and measurements on macro-molecular structures of DNA-CTMA are reported.

  7. Moving Pictures: An Annotated Guide to Selected Film Literature With Suggestions for the Study of Film.

    ERIC Educational Resources Information Center

    Sheahan, Eileen

    Intended as a guide for research in the literature of film, this book lists publications that range from early film writings to books published through mid-1977. Entries are listed alphabetically by author or by title, and are numbered sequentially within the following sections: guides and handbooks, dictionaries and encyclopedias, annuals and…

  8. Study of the photovoltaic effect in thin film barium titanate

    NASA Technical Reports Server (NTRS)

    Grannemann, W. W.; Dharmadhikari, V. S.

    1981-01-01

    The photoelectric effect in structures consisting of metal deposited barium titanate film silicon is described. A radio frequency sputtering technique is used to deposit ferroelectric barium titantate films on silicon and quartz. Film properties are measured and correlated with the photoelectric effect characteristics of the films. It was found that to obtain good quality pin hole free films, it is necessary to reduce the substrate temperature during the last part of the deposition. The switching ability of the device with internal applied voltage is improved when applied with a ferroelectric memory device.

  9. Phase separation in antisymmetric films: A molecular dynamics study

    SciTech Connect

    Krishnan, Raishma; Puri, Sanjay; Jaiswal, Prabhat K.

    2013-11-07

    We have used molecular dynamics (MD) simulations to study phase-separation kinetics in a binary fluid mixture (AB) confined in an antisymmetric thin film. One surface of the film (located at z = 0) attracts the A-atoms, and the other surface (located at z = D) attracts the B-atoms. We study the kinetic processes which lead to the formation of equilibrium morphologies subsequent to a deep quench below the miscibility gap. In the initial stages, one observes the formation of a layered structure, consisting of an A-rich layer followed by a B-rich layer at z = 0; and an analogous structure at z = D. This multi-layered morphology is time-dependent and propagates into the bulk, though it may break up into a laterally inhomogeneous structure at a later stage. We characterize the evolution morphologies via laterally averaged order parameter profiles; the growth laws for wetting-layer kinetics and layer-wise length scales; and the scaling properties of layer-wise correlation functions.

  10. Formation of continuous metallic film on quartz studied by noncontact resonant ultrasound spectroscopy

    SciTech Connect

    Nakamura, N. Yoshimura, N.; Ogi, H.; Hirao, M.

    2015-08-28

    Dynamics of continuous film formation of metallic films on quartz substrates is studied using an electrodeless resonance method. Bare quartz is used as a substrate, and a metallic film is deposited on it. We use antenna transmission technique to measure the evolution of resonance frequencies and internal friction of the substrate during and after deposition, and the morphological transition between discontinuous islands and a continuous film is detected. By comparison with atomic force microscopy images, we confirm that the frequency drop and the internal-friction peak that appear during deposition indicate this transition. We also find that Pt film shows unexpected morphology change after deposition.

  11. Center for Thin-Film Studies. Annual report, 1 October 1986-1 October 1987

    SciTech Connect

    Shannon, R.P.; Gibson, U.J.

    1987-11-15

    This report covers the first year of operation of the URI Thin Film Center (TFC), and describes a diverse array of studies on thin-film materials, substrates, and their processing and analysis. Individual efforts are highlighted in sections on nucleation studies, ion-assisted deposition, Rutherford backscattering spectrometry, Brillouin scattering, a continuum theory of the evolution of structure in thin films, a study of polishing parameters relevant to the preparation of substrates, and the setup of a characterization facility for the Center.

  12. Fibronectin Terminated Multilayer Films: Protein Adsorption and Cell Attachment Studies

    PubMed Central

    Wittmer, Corinne R.; Phelps, Jennifer A.; Saltzman, W. Mark; Van Tassel, Paul R.

    2006-01-01

    Electrostatically driven layer-by-layer (LbL) assembly is a simple and robust method for producing structurally tailored thin film biomaterials, of thickness ca. 10 nanometers, containing biofunctional ligands. We investigate the LbL formation of multilayer films composed of polymers of biological origin (poly(L-lysine) (PLL) and dextran sulfate (DS)), the adsorption of fibronectin (Fn) - a matrix protein known to promote cell adhesion - onto these films, and the subsequent spreading behavior of human umbilical vein endothelial cells (HUVEC). We employ optical waveguide lightmode spectroscopy (OWLS) and quartz crystal microgravimetry with dissipation (QCMD) to characterize multilayer assembly in situ, and find adsorbed Fn mass on PLL terminated films to exceed that on DS terminated films by 40%, correlating with the positive charge and lower degree of hydration of PLL terminated films. The extent and initial rate of Fn adsorption to both PLL and DS terminated films exceed those onto the bare substrate, indicating the important role of electrostatic complexation between negatively charged protein and positively charged PLL at or near the film surface. We use phase contrast optical microscopy to investigate the time dependent morphological changes of HUVEC as a function of layer number, charge of terminal layer, and the presence of Fn. We observe HUVEC to attach, spread, and lose circularity on all surfaces. (Positively charged) PLL terminated films exhibit a greater extent of cell spreading than do (negatively charged) DS terminated films, and spreading is enhanced while circularity loss is suppressed by the presence of adsorbed Fn. The number of layers plays a significant role only for DS terminated films with Fn, where spreading on a bilayer greatly exceeds that on a multilayer, and PLL terminated films without Fn, where initial spreading is significantly higher on a monolayer. We observe initial cell spreading to be followed by retraction (i.e. decreased cell

  13. Film and Language Learning in Victorian Schools: A Study of the 2009 Next Gen Program of the "Melbourne International Film Festival"

    ERIC Educational Resources Information Center

    Lo Bianco, Hana

    2010-01-01

    This article investigates the role of film in language education based on a study of the 2009 "Melbourne International Film Festival" (MIFF). It is structured around a literature review and results from surveys of students and teachers who participated in the young people's section of the program, Next Gen. The article argues that film can provide…

  14. Microhardness studies on thin carbon films grown on P-type, (100) silicon

    NASA Technical Reports Server (NTRS)

    Kolecki, J. C.

    1982-01-01

    A program to grow thin carbon films and investigate their physical and electrical properties is described. Characteristics of films grown by rf sputtering and vacuum arc deposition on p type, (100) silicon wafers are presented. Microhardness data were obtained from both the films and the silicon via the Vickers diamond indentation technique. These data show that the films are always harder than the silicon, even when the films are thin (of the order of 1000 A). Vacuum arc films were found to contain black carbon inclusions of the order of a few microns in size, and clusters of inclusions of the order of tens of microns. Transmission electron diffraction showed that the films being studied were amorphous in structure.

  15. Study of photoluminescence properties of thin films DR1

    NASA Astrophysics Data System (ADS)

    Herman, Ulya, Naily

    2015-09-01

    Fabrication of thin films DR1 have been carried out by the EFA-PDF (Electric Field-Assisted Physical Vapor Deposition) method to obtain films with parallel dipole arrangement. Molecular deposition process is performed by applying an electric field that is placed between the substrate ITO (Indium Tin Oxide) and copper mesh. The resulting films were characterized by using a spectrofluorometer. Analysis of the emission spectrum, indicate that DR1 molecules in the film oriented perpendicular to the substrate and arranged in parallel order (H-aggregate). As an effect, the peak of the emission spectrum appears stronger along with the increase of electric field strength.

  16. Study of indium tin oxide films exposed to atomic axygen

    NASA Technical Reports Server (NTRS)

    Snyder, Paul G.; De, Bhola N.; Woollam, John A.; Coutts, T. J.; Li, X.

    1989-01-01

    A qualitative simulation of the effects of atomic oxygen has been conducted on indium tin oxide (ITO) films prepared by dc sputtering onto room-temperature substrates, by exposing them to an RF-excited oxygen plasma and characterizing the resulting changes in optical, electrical, and structural properties as functions of exposure time with ellipsometry, spectrophotometry, resistivity, and X-ray measurements. While the films thus exposed exhibit reduced resistivity and optical transmission; both of these effects, as well as partial crystallization of the films, may be due to sample heating by the plasma. Film resistivity is found to stabilize after a period of exposure.

  17. Study of photoluminescence properties of thin films DR1

    SciTech Connect

    Herman, Ulya, Naily

    2015-09-30

    Fabrication of thin films DR1 have been carried out by the EFA-PDF (Electric Field-Assisted Physical Vapor Deposition) method to obtain films with parallel dipole arrangement. Molecular deposition process is performed by applying an electric field that is placed between the substrate ITO (Indium Tin Oxide) and copper mesh. The resulting films were characterized by using a spectrofluorometer. Analysis of the emission spectrum, indicate that DR1 molecules in the film oriented perpendicular to the substrate and arranged in parallel order (H-aggregate). As an effect, the peak of the emission spectrum appears stronger along with the increase of electric field strength.

  18. Comparison of diagnostic accuracy of plain film radiographs between original film and smartphone capture: a pilot study.

    PubMed

    Licurse, Mindy Y; Kim, Sung H; Kim, Woojin; Ruutiainen, Alexander T; Cook, Tessa S

    2015-12-01

    The use of mobile devices for medical image capture has become increasingly popular given the widespread use of smartphone cameras. Prior studies have generally compared mobile phone capture images to digitized images. However, many underserved and rural areas without picture archiving and communication systems (PACS) still depend greatly on the use of film radiographs. Additionally, there is a scarcity of specialty-trained or formally licensed radiologists in many of these regions. Subsequently, there is great potential for the use of smartphone capture of plain radiograph films which would allow for increased access to economical and efficient consultation from board-certified radiologists abroad. The present study addresses the ability to diagnose a subset of radiographic findings identified on both the original film radiograph and the captured camera phone image. PMID:25840654

  19. X-Ray and Optical Studies of Thin Organic Films

    NASA Astrophysics Data System (ADS)

    Foster, William Joseph, Jr.

    1995-01-01

    In order to quantitatively understand the fundamental statistical physics of Langmuir monolayers (LMs) it is essential that their properties be measured under equilibrium conditions. In order to address this issue, the phase diagrams of relaxed films of doeicosanoic acid and methyl eicosanoate were mapped out over the temperature range of 5.5^circ to 26 ^circC. In contrast to the prevailing technique in which isotherms are taken at a constant rate of compression, isotherms in this study were taken through a series of incremental compressions, separated by variable waiting periods that allowed the monolayer to relax to a steady state. X-ray diffraction, Brewster angle microscopy, and surface pressure measurements at each area were interpreted to characterize the structure of the phases of a relaxed LM of methyl eicosanoate. Below 12^circ C and 2.25 dynes/cm the I(L_2^ {''}) phase, an orthorhombic structure with tilt toward nearest neighbor was observed. Between 12^circ and 22^ circC and below 8 dynes/cm the F(L _2^') phase, with tilt toward next nearest neighbor and an orthorhombic structure was seen. Above 22^circC the Ov phase, with tilt toward nearest neighbor and a hexagonal structure was seen. At higher pressures, the U ^'(CS)/U(S)/R(LS) sequence of phases, typical of most saturated alkane systems, was detected. In order to better understand issues of equilibrium and relaxation for LMs of the fatty acids and to compare our results to previous "fast" measurements, a detailed study of relaxed films of doeicosanoic acid was conducted. Both relaxation isotherms and isochores were performed simultaneously with x-ray diffraction measurements. It was found that, despite uncertainty in the macroscopic trough area per molecule due to collapse of the film, a physically useful phase diagram could be constructed in terms of the microscopic area per molecule, derived from diffraction measurements. In addition, by using a two-dimensional analog of the Clausius -Clapeyron

  20. Initial thin film penetration studies at the Colorado Center for Lunar Dust and Atmospheric Studies

    NASA Astrophysics Data System (ADS)

    Shu, A. J.; Collette, A.; Drake, K. J.; Gruen, E.; Horanyi, M.; Kempf, S.; Munsat, T.; Northway, P.; Robertson, S. H.; Srama, R.; Sternovsky, Z.; Thomas, E.; Colorado CenterLunar Dust; Atmospheric Studies

    2011-12-01

    Initial studies of damage caused by hypervelocity impacts of various micrometeorite materials into a range of targets are being performed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS). Cratering studies are initially focused on polyvinylidene fluoride (PVDF) films in order to characterize the crater dependencies on impactor mass, size, and speed, and to better understand its capabilities as a dust detector. Additional cratering studies include optical glass, and geological samples as targets. These studies will lead to a better understanding of damage to spacecraft windows and instruments, and space weathering on airless bodies. In parallel, penetration studies will be conducted to determine how hole sizes in thin film materials depend on the properties of the film and the projectile. These thin film penetration studies will be critical to the design of dust detectors similar to that used on NASA's Stardust and New Horizons spacecraft, and in the design of solar sails. Thin film detectors can also be used to characterize beam profiles of laboratory dust accelerators. These studies are being performed at the 3MV hypervelocity dust accelerator at CCLDAS. The facility can accelerate dust particles up to 10's of km/s with user control over the velocity and mass ranges of particles reaching the target chamber. Complementary studies will be conducted at the Johnson Space Center Light Gas Gun using the same target and particle properties. These parallel studies will allow us to cover an extended range of acceleration parameters as well as better understand the similarities and differences between electrostatic accelerators and light gas guns.

  1. Contact angle and film pressure: study of a talc surface.

    PubMed

    Douillard, J M; Zajac, J; Malandrini, H; Clauss, F

    2002-11-15

    Talc samples in both sheet and powder form are studied by adsorption calorimetry and adsorption isotherm techniques. A model is used to determine the solid surface energy, the solid surface tension and the dispersive, acidic, and basic components of these terms. These results are introduced in an approximate equation relating adsorption to contact angle data. Experimental contact angles are in correct agreement with this approach. The Neumann equation of state is used to fit the data and discussed. It appears as a numerical form of the general equation taking into account gas adsorption and film pressure. Behaviors of talc in contact with liquids do not appear very different whether the solid is in sheet or powder form. PMID:12505082

  2. Theoretical and material studies of thin-film electroluminescent devices

    NASA Technical Reports Server (NTRS)

    Summers, C. J.

    1989-01-01

    Thin-film electroluminescent (TFEL) devices are studied for a possible means of achieving a high resolution, light weight, compact video display panel for computer terminals or television screens. The performance of TFEL devices depends upon the probability of an electron impact exciting a luminescent center which in turn depends upon the density of centers present in the semiconductor layer, the possibility of an electron achieving the impact excitation threshold energy, and the collision cross section itself. Efficiency of such a device is presently very poor. It can best be improved by increasing the number of hot electrons capable of impact exciting a center. Hot electron distributions and a method for increasing the efficiency and brightness of TFEL devices (with the additional advantage of low voltage direct current operation) are investigated.

  3. Raman studies of lattice dynamics and phase transitions in barium strontium titanate thin films

    NASA Astrophysics Data System (ADS)

    Tenne, D. A.; Xi, X. X.; Li, Y. L.; Chen, L. Q.; Soukiassian, A.; Schlom, D. G.; Taylor, T. R.; Hansen, P. J.; Speck, J. S.; York, R. A.; Choosuwan, H.; He, Qi; Guo, R.; Bhalla, A. S.

    2004-03-01

    The lattice dynamics and phase transitions in Ba_xSr_1-xTiO3 (BST) thin films single crystals were studied by Raman spectroscopy. Our studies revealed essential differences in the lattice dynamical properties Ba_xSr_1-xTiO3 films and single crystals: Forbidden first order Raman scattering in BST films well above the bulk phase transition temperature where the crystals show the second order Raman features only; hardening of the soft phonon modes in films compared to crystals; significantly larger range of the E soft mode overdamping in films, which supposes an additional damping mechanism in films, not present in crystals. Lattice dynamics behavior in the BST films is similar to that of relaxor ferroelectrics. Analogously to the relaxors, the existence of polar nanoregions in the films at the above the bulk Curie-Weiss temperature explains the specific lattice-dynamical properties of BST films. The effect of strain on the phase transitions in Ba_xSr_1-xTiO3 thin films will also be discussed. In polycrystalline BST films grown on the substrates providing a systematic change in the thermal strain, it was found that the out-of-plane polarization is likely locked during the growth and cooling processes. This leads to a decreasing of the Tc with increasing tensile strain. In the epitaxial BaTiO3 films, the Raman studies show that the tetragonal-orthorhombic-rhombohedral phase transitions, characteristic of bulk BaTiO_3, are completely absent due to the presence of tensile strain. This is confirmed by a phase diagram for BaTiO3 film obtained from thermodynamic phase-field calculations.

  4. Comparative Study of Cu Films Prepared by DC, High-Power Pulsed and Burst Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Solovyev, A. A.; Oskirko, V. O.; Semenov, V. A.; Oskomov, K. V.; Rabotkin, S. V.

    2016-05-01

    A comparative study of deposition rate, adhesion, structural and electrical properties of nanocrystalline copper thin films deposited using direct current magnetron sputtering (DCMS) and different regimes of high power pulsed magnetron sputtering is presented. High-power impulse magnetron sputtering (HIPIMS) and burst regime (pulse packages) of magnetron sputtering are investigated. The ion and atomic flows toward the growing film during magnetron sputtering of a Cu target are determined. X-ray diffraction, scanning electron microscopy and atomic force microscopy were used to observe the structural characterization of the films. The resistivity of the films was measured using four-point probe technique. In all sputtering regimes, Cu films have mixture crystalline orientations of [111], [200], [311] and [220] in the direction of the film growth. As peak power density in studied deposition regimes was different in order of magnitude (from 15 W/cm2 in DC regime to 3700 W/cm2 in HIPIMS), film properties were also greatly different. DCMS Cu films exhibit a porous columnar grain structure. In contrast, HIPIMS Cu films have a slightly columnar and denser composition. Cu films deposited using burst regimes at peak power density of 415 W cm-2 and ion-to-atom ratio of about 5 have the densest composition and smallest electrical resistance.

  5. Comparative Study of Cu Films Prepared by DC, High-Power Pulsed and Burst Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Solovyev, A. A.; Oskirko, V. O.; Semenov, V. A.; Oskomov, K. V.; Rabotkin, S. V.

    2016-08-01

    A comparative study of deposition rate, adhesion, structural and electrical properties of nanocrystalline copper thin films deposited using direct current magnetron sputtering (DCMS) and different regimes of high power pulsed magnetron sputtering is presented. High-power impulse magnetron sputtering (HIPIMS) and burst regime (pulse packages) of magnetron sputtering are investigated. The ion and atomic flows toward the growing film during magnetron sputtering of a Cu target are determined. X-ray diffraction, scanning electron microscopy and atomic force microscopy were used to observe the structural characterization of the films. The resistivity of the films was measured using four-point probe technique. In all sputtering regimes, Cu films have mixture crystalline orientations of [111], [200], [311] and [220] in the direction of the film growth. As peak power density in studied deposition regimes was different in order of magnitude (from 15 W/cm2 in DC regime to 3700 W/cm2 in HIPIMS), film properties were also greatly different. DCMS Cu films exhibit a porous columnar grain structure. In contrast, HIPIMS Cu films have a slightly columnar and denser composition. Cu films deposited using burst regimes at peak power density of 415 W cm-2 and ion-to-atom ratio of about 5 have the densest composition and smallest electrical resistance.

  6. a Study of the Morphology of Pmda-Oda Polyimide Films.

    NASA Astrophysics Data System (ADS)

    Stone, Craig Douglas

    This research examines how the morphology of PMDA -ODA polyimide films varies as a condition of production and post-imidization treatments. These films were produced using chemical and thermal imidization techniques. The PMDA-ODA films were studied using four different techniques. Optical anisotropy, density and wide and small-angle x-ray scattering measurements were made. Wide-angle x-ray diffraction was used to examine the short-range nature of the ordering while small-angle x-ray scattering was used for long-period spacing and void studies. This research shows that the morphology of PMDA -ODA films depends on the method of imidization. The chemically imidized PMDA-ODA varies from the thermally imidized films. The chemically imidized films are more in-plane and out-of -plane anisotropic which is a result of the lateral stress applied to the film during imidization. These commercially prepared films (Du Pont Kapton^circler) are cast on a high-speed conveyor which applies the stress to the polyamic acid precursor. The thermally imidized films, in contrast, are cast onto glass plates which does not subject them to the same degree of stress. The chemically imidized films also had larger void sizes ( ~35 A compared to ~ 25A) and smaller void fractions. The stresses applied to Kapton^circler resulted in the enlargement of the voids during imidization. For Kapton^circler, the lower void fractions in the thinner films resulted both from the thickness of the film which allowed voids to escape more easily and the larger ordered domains in these samples. The PMDA-ODA films were also thermally treated and soaked in water. The water immersion studies helped to prove the existence of the voids within the films. Although most of the thermal treatments had some effect on the polyimide films, these effects are small at lower temperatures. Upon annealing at temperatures of 450 ^circC, this film experienced a major change in morphology. In addition to degradation of the material

  7. "Making the Devil Useful": Film Studies in the English Curriculum.

    ERIC Educational Resources Information Center

    Bruder, Carolyn R.

    Film is not often taught for itself and by itself; it is too often viewed as the handmaiden of literature. More often than not it is taught in English departments because: (1) like novels, poems, plays and philosophical arguments, it is a humanistic text; (2) film writers and directors have historically turned to literary texts as their source…

  8. Growth and study of antimony selenide island films

    NASA Astrophysics Data System (ADS)

    Kushkhov, A. R.; Gaev, D. S.; Rabinovich, O. I.; Stolyarov, A. G.

    2013-03-01

    Nanosized Sb2Se3 island films are prepared by the incongruent evaporation of Sb1 - x Se x ( x = 0.9 at fractions) thin films. The surface morphology of the structures is investigated by optical and atomic force microscopy (AFM). It is shown that an increase in the evaporation temperature leads to a decrease in the surface density of islands.

  9. Slow-Positron Generator For Studying Polymer Films

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; St. Clair, Terry L.; Eftekhari, Abe

    1992-01-01

    Aspects of molecular structures probed by positron-annihilation spectroscopy (PAS). Slow-positron-beam generator suitable for PAS measurements in thin polymer films. Includes Na22 source of positrons and two moderators made of well-annealed tungsten foil. With proper choice of voltage, positrons emitted by inward-facing surfaces of moderators made to stop in polymer films tested.

  10. Some studies on successive ionic layer adsorption and reaction (SILAR) grown indium sulphide thin films

    SciTech Connect

    Pathan, H.M.; Lokhande, C.D. . E-mail: l_chandrakant@yahoo.com; Kulkarni, S.S.; Amalnerkar, D.P.; Seth, T.; Han, Sung-Hwan . E-mail: shhan@hanyang.ac.kr

    2005-06-15

    Indium sulphide (In{sub 2}S{sub 3}) thin films were grown on amorphous glass substrate by the successive ionic layer adsorption and reaction (SILAR) method. X-ray diffraction, optical absorption, scanning electron microscopy (SEM) and Rutherford back scattering (RBS) were applied to study the structural, optical, surface morphological and compositional properties of the indium sulphide thin films. Utilization of triethanolamine and hydrazine hydrate complexed indium sulphate and sodium sulphide as precursors resulted in nanocrystalline In{sub 2}S{sub 3} thin film. The optical band gap was found to be 2.7 eV. The film appeared to be smooth and homogeneous from SEM study.

  11. Tribological studies of amorphous hydrogenated carbon films in a vacuum, spacelike environment

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1991-01-01

    Recent work on the adhesion and friction properties of plasma-deposited amorphous hydrogenated carbon films and their dependence on preparation conditions are reviewed. The results of the study indicate that plasma deposition enables one to deposit a variety of amorphous hydrogenated carbon (a-C:H) exhibiting diamondlike friction behavior. The plasma-deposited a-C:H films can be effectively used as hard lubricating films on ceramic materials such as silicon nitride in vacuum.

  12. X-ray diffraction studies of sprayed SnO 2: Sb films

    NASA Astrophysics Data System (ADS)

    Goyal, D. J.; Agashe, Chitra; Takwale, M. G.; Bhide, V. G.

    1993-06-01

    Antimony-doped tin oxide films were deposited by spray pyrolysis on Corning 7059 substrates. The structural and electrical properties of the films deposited with different doping levels were studied. Relative variations in the structural properties were explained on the basis of structure factor calculations. The results show that the incorporation of antimony atoms takes place only at substitutional sites. As expected, the substitutional replacement of tin by antimony atoms increased appreciably the free carrier density of the film.

  13. Nanoindentation Studies Of Hard Nanocomposite Ti-B-N Thin Films

    SciTech Connect

    Rupa, P. Karuna Purnapu; Chakraborty, P. C.; Mishra, Suman Kumari

    2011-12-12

    Titanium boron nitride (Ti-B-N) films were deposited by reactive magnetron sputtering using single Titanium diboride (TiB{sub 2}) target in different Ar-N{sub 2} gas mixtures. The influence of N{sub 2}:Ar ratio on the microstructure and mechanical properties of the deposited films have been investigated. Atomic force microscopy analysis indicated the grain size decreases with incorporation of nitrogen in the films. Nanoindentation studies have shown the hardness decreases with nitrogen incorporation.

  14. Dynamic study of nanodroplet nucleation and growth on self-supported nanothick liquid films.

    PubMed

    Barkay, Z

    2010-12-01

    The dynamics of water condensation on self-supported thin films was studied at the nanoscale using transmitted electrons in an environmental scanning electron microscope. The initial stages of nucleation and growth over nanothick water films have been investigated. Irregularities at the water-film boundaries constituted nucleation sites for asymmetric dropwise and filmwise condensation. Nanodroplet growth was associated with center of mass movement, and the dynamic growth power law dependence was explored for the nanoscale. PMID:21073155

  15. Synthesis, characterization and ellipsometric study of ultrasonically sprayed Co3O4 films

    NASA Astrophysics Data System (ADS)

    Gençyılmaz, O.; Taşköprü, T.; Atay, F.; Akyüz, İ.

    2015-10-01

    In the present study, cobalt oxide (Co3O4) films were produced using ultrasonic spray pyrolysis technique onto the glass substrate at different temperatures (200-250-300-350 °C). The effect of substrate temperature on the structural, optical, surface and electrical properties of Co3O4 films was reported. Thickness, refractive index and extinction coefficient of the films were determined by spectroscopic ellipsometry, and X-ray diffraction analyses revealed that Co3O4 films were polycrystalline fcc structure and the substrate temperature significantly improved the crystal structure of Co3O4 films. The films deposited at 350 °C substrate temperature showed the best structural quality. Transmittance, absorbance and reflectance spectra were taken by means of UV-Vis spectrophotometer, and optical band gap values were calculated using optical method. Surface images and roughness values of the films were taken by atomic force microscopy to see the effect of deposition temperature on surface properties. The resistivity of the films slightly decreases with increase in the substrate temperature from 1.08 × 104 to 1.46 × 102 Ω cm. Finally, ultrasonic spray pyrolysis technique allowed production of Co3O4 films, which are alternative metal oxide film for technological applications, at low substrate temperature.

  16. A study on the wet etching behavior of AZO (ZnO:Al) transparent conducting film

    NASA Astrophysics Data System (ADS)

    Lin, Y. C.; Jian, Y. C.; Jiang, J. H.

    2008-02-01

    This paper studies the wet etching behavior of AZO (ZnO:Al) transparent conducting film with tetramethylammonium hydroxide (TMAH). The optimum optoelectronic film is prepared first using designated RF power, film thickness and controlled annealing heat treatment parameters. The AZO film is then etched using TMAH etchant and AZ4620 photoresist with controlled etchant concentration and temperature to examine the etching process effect on the AZO film optoelectronic properties. The experimental results show TMAH:H 2O = 2.38:97.62 under 45 °C at the average etch rate of 22 nm/min as the preferred parameters. The activation energy drops as the TMAH concentration rises, while the etch rate increases along with the increase in TMAH concentration and temperature. After lithography, etching and photoresist removal, the conductivity of AZO film dramatically drops from 2.4 × 10 -3 Ω cm to 3.0 × 10 -3 Ω cm, while its transmittance decreases from 89% to 83%. This is due to the poor chemical stability of AZO film against AZ4620 photoresist, leading to an increase in surface roughness. In the photoresist postbaking process, carbon atoms diffused within the AZO film produce poor crystallinity. The slight decreases in zinc and aluminum in the thin film causes a carrier concentration change, which affect the AZO film optoelectronic properties.

  17. Anomalous Hall effect studies on Tb-Fe thin films

    NASA Astrophysics Data System (ADS)

    Rajasekhar, P.; Deepak Kumar, K.; Markandeyulu, G.

    2016-08-01

    Tbx Fe100-x (with x=11, 25, 31 and 44) thin films were prepared with the substrates kept at a temperature of 300 °C and the Hall resistivities and electrical resistivities were investigated in the temperature range 25-300 K. The sign of Hall resistivity is found to change from positive for x=31 to negative for x=44 film at temperatures 25 K and 300 K, reflecting the compensation of Tb and Fe magnetic moments between these two compositions. Perpendicular magnetic anisotropy was observed in the films of x=25 and 31 at 25 K as well as at 300 K. The Hall resistivity is seen to increase for the films of x=11 and 31 with increasing temperature, while it decreases for the films of x=25 and 44 with increasing temperature. The temperature coefficients of electrical resistivities of these films are seen to be positive. The presence of perpendicular magnetic anisotropy (refers to magnetic anisotropy, in this paper) in the temperature range 25-300 K in Tb25Fe75 and Tb31Fe69 and their metallic nature are indicators that the Tb-Fe films deposited at higher temperatures are more suitable for magneto optic data storage applications than their amorphous counterparts, due to the stability of the former.

  18. A comparative study: Effect of plasma on V2O5 nanostructured thin films

    NASA Astrophysics Data System (ADS)

    Singh, Megha; Kumar, Prabhat; Sharma, Rabindar K.; Reddy, G. B.

    2016-05-01

    Vanadium pentoxide nanostructured thin films (NSTs) have been studied to analyze the effect of plasma on nanostructures grown and morphology of films deposited using sublimation process. Nanostructured thin films were deposited on glass substrates, one in presence of oxygen plasma and other in oxygen environment (absence of plasma). Films were characterized using XRD, Raman spectroscopy, SEM and HRTEM. XRD studies revealed α-V2O5 films (orthorhombic phase) with good crystallinity. However, film deposited in presence of plasma have higher peak intensities as compared to those deposited in absence of plasma. Raman studies also support these finding following same trends of considerable increase in intensity in case of film deposited in presence of plasma. SEM micrographs makes the difference more visible, as film deposited in plasma have well defined plate like structures whereas other film have not-clearly-defined petal-like structures. HRTEM results show orthorhombic phase with 0.39 nm interplanar spacing, as reported by XRD. Results are hereby in good agreement with each other.

  19. Study of CVD SiC thin film for space mirror

    NASA Astrophysics Data System (ADS)

    Zhang, Jianhan; Zhang, Yumin; Han, Jiecai; He, Xiaodong

    2006-01-01

    The performance of space mirror lied on the properties of the mirror surface material to a great extent. In this paper, the silicon carbide thin film deposited on reaction-bonded silicon carbide (RBSC) space mirror blank was produced by Chemical Vapor Deposition (CVD) process. Some mechanical and physical properties of the SiC thin film were tested because they were important to study ability to work of space mirror. The result of XRD phase analysis indicated that the component of the SiC thin film was β-SiC. The micro hardness of the film was tested. The thickness of SiC thin film was tested using needle touch contour graph. The results showed that the thickness of SiC film was about 20 μm and film was even in the macro scope. The adhesion strength of SiC thin film and RBSC substrate was tested by scratch method and the results showed that was excellent. The residual stress of SiC thin film was tested by X-ray, at the same time; the origin of residual stress and the calculation of thermal stress were discussed. In the room temperature, the residual stress of the SiC film was compressive. After precision grinding, the surface topography and roughness of the SiC thin film was tested by Atomic Force Microscope (AFM). The results showed that the surface of SiC thin film had extremely low surface roughness and high surface form accuracy. The thermal shock resistance of SiC film was fine by tested.

  20. XRay Study of Transfer Printed Pentacene Thin Films

    SciTech Connect

    Shao, Y.; Solin, S. A.; Hines, D. R.; Williams, E. D.

    2007-04-10

    We investigated the structural properties and transfer properties of pentacene thin films fabricated by thermal deposition and transfer printing onto SiO2 and plastic substrates, respectively. The dependence of the crystallite size on the printing time, temperature and pressure were measured. The increases of crystalline size were observed when pentacene thin films were printed under specific conditions, e.g. 120 deg. C and 600 psi and can be correlated with the improvement of the field effect mobility of pentacene thin-film transistors.

  1. Study for Electrode Metals on Taste Sensor with LB film

    NASA Astrophysics Data System (ADS)

    Yokoya, Takahiro; Hirata, Takamichi; Akiya, Masahiro

    In this paper, sensor responses with only metal electrode as Au, Cr, Ti and more with LB film were described. LB film material was the Dioctadecyldimethylammonium bromide combined by PVSK as an underlayer. To detect five basic taste substances, sensor parameters were defined as maximum voltage change and response time. Response time for sourness and umami with Ti and Cr evaporated metal electrode was larger than that of usual Au electrode. LB film effect was finally found to increase response time for five basic taste materials.

  2. Photoconductivity studies on amorphous and crystalline TiO2 films doped with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Valverde-Aguilar, G.; García-Macedo, J. A.; Rentería-Tapia, V.; Aguilar-Franco, M.

    2011-06-01

    In this work, amorphous and crystalline TiO2 films were synthesized by the sol-gel process at room temperature. The TiO2 films were doped with gold nanoparticles. The films were spin-coated on glass wafers. The crystalline samples were annealed at 100°C for 30 minutes and sintered at 520°C for 2 h. All films were characterized using X-ray diffraction, transmission electronic microscopy and UV-Vis absorption spectroscopy. Two crystalline phases, anatase and rutile, were formed in the matrix TiO2 and TiO2/Au. An absorption peak was located at 570 nm (amorphous) and 645 nm (anatase). Photoconductivity studies were performed on these films. The experimental data were fitted with straight lines at darkness and under illumination at 515 nm and 645 nm. This indicates an ohmic behavior. Crystalline TiO2/Au films are more photoconductive than the amorphous ones.

  3. The study of MgB2/BN/MgB2 trilayer films

    NASA Astrophysics Data System (ADS)

    Hu, Hui; Feng, Qingrong; Wang, Yue; Zhang, Yan

    2015-12-01

    MgB2/BN/MgB2 trilayer films have been fabricated by using hybrid physical-chemical vapor deposition (HPCVD) method for the MgB2 layers and chemical vapor deposition (CVD) method for the BN layers in the same reactor. The films are studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) and magnetization measurements. These test outcomes indicate the trilayer films are grown without deteriorating the superconductivity of MgB2 films. Our results show that it is feasible to grow MgB2/BN/MgB2 trilayer films in the same reactor sequentially, which has the advantage of reducing contamination during the growth. This therefore opens the door for fabricating all-MgB2 Josephson junctions by using the BN film as the insulating layer.

  4. Microstructure investigation and magnetic study of permalloy thin films grown by thermal evaporation

    NASA Astrophysics Data System (ADS)

    Lamrani, Sabrina; Guittoum, Abderrahim; Schäfer, Rudolf; Pofahl, Stefan; Neu, Volker; Hemmous, Messaoud; Benbrahim, Nassima

    2016-06-01

    We study the effect of thickness on the structural and magnetic properties of permalloy thin films, evaporated on glass substrate. The films thicknesses range from 16 to 90 nm. From X-ray diffraction spectra analysis, we show that the thinner films present a "1,1,1" preferred orientation. However, the thicker films exhibit a random orientation. The grains size increases and the lattice parameter decreases with increasing thickness. The magnetic force microscopy observations display cross-tie walls features only for the two thicker films (60 and 90 nm thick films). The magnetic microstructure, carried out by Kerr microscopy technique, shows the presence of magnetic domains changing with the direction of applied magnetic field. The coercive field, Hc, was found to decrease from 6.5 for 16 to 1.75 Oe for 90 nm. All these results will be discussed and correlated.

  5. Vibrational properties of epitaxial Bi4Te3 films as studied by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Hao; Song, Yuxin; Pan, Wenwu; Chen, Qimiao; Wu, Xiaoyan; Lu, Pengfei; Gong, Qian; Wang, Shumin

    2015-08-01

    Bi4Te3, as one of the phases of the binary Bi-Te system, shares many similarities with Bi2Te3, which is known as a topological insulator and thermoelectric material. We report the micro-Raman spectroscopy study of 50 nm Bi4Te3 films on Si substrates prepared by molecular beam epitaxy. Raman spectra of Bi4Te3 films completely resolve the six predicted Raman-active phonon modes for the first time. Structural features and Raman tensors of Bi4Te3 films are introduced. According to the wavenumbers and assignments of the six eigenpeaks in the Raman spectra of Bi4Te3 films, it is found that the Raman-active phonon oscillations in Bi4Te3 films exhibit the vibrational properties of those in both Bi and Bi2Te3 films.

  6. Crystal structure of thin oxide films grown on Zr-Nb alloys studied by RHEED

    NASA Astrophysics Data System (ADS)

    Khatamian, D.; Lalonde, S. D.

    1997-05-01

    The highly surface sensitive reflection high energy electron diffraction (RHEED) technique was used to determine thecrystal structure of oxide films grown on Zr-Nb alloys in air up to 673 K. The results show that the oxide films grown on Zr-2.5 wt% Nb(α-Zr + β-Zr) have a mixture of nearly-cubic-tetragona and monoclinic structures for films of 200 nm thick or less and that the outer layers of films thicker than 800 nm only have the monoclinic crystal structure. However, oxide films grown on Zr-20 wt% Nb (β-Zr) have a stabilized nearly-cubic-tetragonal structure for all film thicknesses, studied here, up to 2100 nm.

  7. Study of photoconductivity in Ni doped CdS thin films prepared by spray pyrolysis technique

    SciTech Connect

    Patidar, Manju Mishra Gangrade, Mohan; Nath, R.; Ganesan, V.; Ajay, Akhil; Wala, Arwa Dewas; N, Kiran; Panda, Richa

    2014-04-24

    Ni-doped cadmium sulphide [Cd{sub 1−x}Ni{sub x}S, (x=0, 0.03, 0.05 and 0.20)] thin films were investigated for photoconductive properties. The films were prepared by spray Pyrolysis technique (SPT). AFM and two probe resistivity measurements were carried out to analyze the morphological and electrical properties of the films. AFM shows the note worthy changes in the morphology where the nanorod structures in CdS is changed into nano particles with the Ni doping. The presence of persistence photo current is demonstrated and extensive photoconductivity analysis has been studied on these films.

  8. Elastic properties of supported polycrystalline thin films and multilayers: An X-ray diffraction study

    SciTech Connect

    Goudeau, P.; Villain, P.; Tamura, N.; Renault, P.-O.; Badawi, K.F.; Padmore, H.A.

    2003-08-13

    Numerous experimental and theoretical studies have shown that thin film elastic behavior may be different from the bulk one due to size effects related to grain boundaries, free surfaces and interfaces. In addition, thin films often present high compressive residual stresses which may be responsible of thin film buckling. These two features will be discussed in this communication through recent x-ray diffraction experiments: in situ tensile testing for elastic constant analysis and scanning x-ray micro diffraction for stress relaxation measurements associated with film buckling.

  9. Molecular dynamics studies of thin film nucleation and substrate modification

    NASA Astrophysics Data System (ADS)

    Hu, Yanhong

    Deposition of energetic particles on solid surfaces has found increasing application in surface science. However, the detailed surface chemistry and relevant atomic mechanisms are not well understood. Molecular dynamics (MD) simulations are an ideal method to study these processes atomistically because they usually occur on short time scales (of the order of a few picoseconds). In this dissertation, MD simulations are performed to investigate thin film formation through organic cluster beam deposition and chemical modification of carbon nanotube/polymer composites via polyatomic ion beam deposition. The interatomic forces are calculated from the reactive empirical bond-order (REBO) potential for carbon-based systems coupled with the Lennard-Jones potentials. The reliability of this approach is examined by comparing its predictions for ethylene-cluster beam deposition with the results of a more accurate order-N nonorthogonal tight-binding method. The results show that the REBO potential captures the general characters of the relevant chemistry. The deposition processes of interest occur at room temperature; hence, appropriate temperature control methods must be employed in the simulations. A comparison study of four temperature control methods during the simulation of cluster deposition finds that the generalized Langevin equation approach is sufficient for dissipation of excess system energy if the deposition occurs on a large enough substrate at a moderate incident energy (<40 eV/cluster-atom). A new temperature control method has been developed for use at higher incident energies. In the simulations of thin film formation through organic cluster beam deposition, the dependence of the results on the intracluster bonding, incident angle and deposition direction is examined. Beams of ethylene clusters, adamantane molecules, and C20 molecules are thus deposited on a diamond surface with varying lateral momenta along two different crystallographic orientations at

  10. Study of NbC thin films for soft X-ray multilayer applications

    SciTech Connect

    Singh, Amol E-mail: rrcat.amol@gmail.com; Modi, Mohammed H.; Lodha, G. S.; Rajput, Parasmani; Jha, S. N.

    2015-06-24

    Compound materials are being used in soft x-ray and Extreme ultraviolet (EUV) optics applications. Structural properties of compound materials changes drastically when ultrathin films are formed from bulk material. Structural properties need to be investigated to determine the suitability of compound materials in soft x-ray multilayer applications. In the present study Niobium carbide (NbC) thin films were deposited using ion beam sputtering of an NbC target on Si (100) substrate. Thickness roughness and film mass density was determined from the X-ray reflectivity (XRR) data. XRR data revealed that the film mass density was increasing with increase in film thickness. For 500Ǻ thick film, mass density of 6.85 g/cm{sup 3}, close to bulk density was found. Rms roughness for all the films was less than 10Å. Local structure of NbC thin films was determined from EXAFS measurements. The EXAFS data showed an increase in Nb-C and Nb-(C)-Nb peak ratio approaches towards bulk NbC with increasing thickness of NbC. From the present study, NbC thin films were found suitable for actual use in soft x-ray multilayer applications.

  11. Study of the photovoltaic effect in thin film barium titanate

    NASA Technical Reports Server (NTRS)

    Grannemann, W. W.; Dharmadhikari, V. S.

    1983-01-01

    The feasibility of making non-volatile digital memory devices of barium titanate, BaTiO3, that are integrated onto a silicon substrate with the required ferroelectric film produced by processing, compatible with silicon technology was examined.

  12. In-situ spectroscopic studies of electrochromic tungsten oxide films

    NASA Astrophysics Data System (ADS)

    Ozer, Nilgun; Demirbas, Muharrem; Ozyurt, Secuk

    2001-11-01

    Tungsten oxide thin films were prepared using an ethanolic solution of tungsten hexachloride (WCl6) by sol-gel spin coating. The films were spin coated on indium tin oxide (ITO) coated glass substrate at temperatures in the range of 100 to 450 degree(s)C. The films were characterized by x-ray diffractometry (XRD), scanning electron microscopy (SEM) UV- visible spectroscopy and cyclic voltammetry (CV). XRD showed that they had a polycrystalline WO3 structure for heat treatment temperatures at above 350 degree(s)C. The SEM examinations showed that the surface texture was very uniform and homogeneous. In situ electrochemical reduction of WO3/ITO (2M HCl) produced a blue color in less than a second. Coloration efficiency (CE) was found to be 21 cm2/mC. In situ spectroscopic investigations showed that these films could be used as a working electrode in electrochromic devices.

  13. The structure study of thin semiconductor and dielectric films by diffraction of synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Yurjev, G. S.; Fainer, N. I.; Maximovskiy, E. A.; Kosinova, M. L.; Sheromov, M. A.; Rumyantsev, Yu. M.

    1998-02-01

    The structure of semiconductor and dielectric thin (100-300 nm) films was studied by diffraction of synchrotron radiation. The diffraction experiments were performed at both the station "Anomalous scattering" of the storage ring synchrotron facility VEPP-3 and DRON-4 diffractometer. The structure of CdS thin films grown on fused silica, single Si(100) and InP(100) substrates was investigated. The structure of Cu 2S thin films grown on fused silica, single Si(100) substrates and CdS/Si(100)-heterostructure was studied. The structure study was performed on Si 3N 4 films grown on GaAs(100) substrates. The structure of thin BN layers grown on single Si(100) substrates was studied. It was established that structural parameters of above-mentioned thin films coincide on the parameters of JCPDS International Centre for Diffraction Data.

  14. Growth and study of antimony selenide island films

    SciTech Connect

    Kushkhov, A. R.; Gaev, D. S.; Rabinovich, O. I.; Stolyarov, A. G.

    2013-03-15

    Nanosized Sb{sub 2}Se{sub 3} island films are prepared by the incongruent evaporation of Sb{sub 1-x}Se{sub x} (x = 0.9 at fractions) thin films. The surface morphology of the structures is investigated by optical and atomic force microscopy (AFM). It is shown that an increase in the evaporation temperature leads to a decrease in the surface density of islands.

  15. Study of the I-V characteristics of nanostructured Pd films on a Si substrate after vacuum annealing

    SciTech Connect

    Tomilin, S. V. Yanovsky, A. S.; Tomilina, O. A.; Mikaelyan, G. R.

    2013-06-15

    The I-V characteristics of nanostructured Pd films on a Si substrate are investigated. The nanostructures (nanoislands) are formed by the vacuum annealing of continuous ultrathin Pd films sputtered onto a substrate. The shape of the I-V characteristics of the investigated Si substrate-Pd film system is shown to be heavily dependent on the degree of film nanostructuring. The surface morphology of the films is studied using scanning electron microscopy.

  16. A Technical, User and Cost Comparison Study of Microfiche Duplicate Film Material. Final Report.

    ERIC Educational Resources Information Center

    Prevel, James J.

    A technical, user and cost comparison study was undertaken to provide the Educational Resources Information Clearinghouse (ERIC) staff with data on silver halide, diazo, and vesicular type films for microfiche duplication. This information will allow ERIC to determine if diazo and/or vesicular films should be considered in producing ERIC duplicate…

  17. Experimental study of interfacial structure of a falling liquid film in a vertical pipe

    NASA Astrophysics Data System (ADS)

    Hasan, Abbas; Azzopardi, Barry; Hewakandamby, Buddhika

    2015-11-01

    Many studies in the literature provide time series data of the film thickness at one or two points on the pipe wall. Most of these studies focussed on either flat plates or small diameter pipes. The main aim of this paper is to study the characteristics of the interfacial wave structure of falling liquid films (liquid Reynolds numbers: 618-1670) in a large diameter pipe (127 mm) using a Multiple Pin Film Sensor (MPFS) which is capable of providing measurements of film thickness and interfacial waves with excellent resolution in time and in the circumferential and axial directions. Parameters, such as film thicknesses, wave velocities and frequencies were extracted. 3D interfacial wave structures were reconstructed from the film thickness data. Unlike the waves in smaller diameter pipes which are characterised as coherent rings, the waves seen in this study were much localized. The mean film thicknesses are generally in good agreement with published models. The mean film thickness obtained from MPFS was also compared with the conductance ring pairs. There is good agreement between the two methods particularly when the fact that the ring pair technique provides a circumferentially averaged value. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  18. Comparative study on properties of edible films based on pinhao (Araucaria angustifolia) starch and flour

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of this study was to develop and compare the properties of edible films based on pinhao starch and pinhao flour. Seven formulations were developed by casting methodology: 5% pinhao starch with 0, 1, 1.5, and 2% glycerol, and 5% pinhao flour with 1, 1.5, and 2% glycerol. The films were evalua...

  19. Teaching Film and Television in Developing Nations: A Malaysian Case Study.

    ERIC Educational Resources Information Center

    Hooper, Robert A.

    1997-01-01

    Recounts an American film studies professor's professional and personal experiences in teaching in Malaysia--the campus television studios burned to the ground the morning he arrived. Comments on the difficulties in film production in developing countries and on his Malaysian students' determination and capabilities. (PA)

  20. Uniting Hispanic Film Studies with Civic Engagement: A Chance for Personal Transformation

    ERIC Educational Resources Information Center

    Larson, Kajsa C.

    2015-01-01

    This current study presents a unique approach to the examination of Hispanic film through the incorporation of a civic engagement project, the Mayerson Student Philanthropy Project (MSPP), into the curriculum. Students examined and assessed important global issues, and how they are portrayed in films from several Spanish-speaking countries, while…

  1. Towards a Decolonising Pedagogy: Understanding Australian Indigenous Studies through Critical Whiteness Theory and Film Pedagogy

    ERIC Educational Resources Information Center

    Hook, Genine

    2012-01-01

    This article explores student and teacher engagement with Australian Indigenous Studies. In this article I identify key themes in the film "September" (2007) that demonstrate how the film can be used as a catalyst for student learning and discussion. Critical whiteness theory provides a framework to explore three themes, the invisibility of…

  2. Active Learning through Student Film: A Case Study of Cultural Geography

    ERIC Educational Resources Information Center

    Anderson, Jon

    2013-01-01

    This study contributes to the debate over the potential of film as a pedagogical aid. It argues that integrating film production into the assessment of undergraduate modules secures advantages for student learning: students connect their ideas more explicitly to "real world" examples; new voices and understandings are introduced to…

  3. Film Study and the Teaching of English: Technology and the Future of Pedagogy.

    ERIC Educational Resources Information Center

    Gallagher, Brian

    1988-01-01

    Offers six predictions on the interrelated development of film technology and film study in the teaching of English. Sees the instructional centrality of the video cassette recorder in the near future, progressing to microcomputers, laser disks, and hybrid spoken-written-graphic text. (MM)

  4. The Influence of the MPAA's Film Rating System on Motion Picture Attendance: A Pilot Study.

    ERIC Educational Resources Information Center

    Austin, Bruce A.

    A study was undertaken to design and implement an experimental instrument for testing the influence of the Motion Picture Association of America's (MPAA) film rating system on movie attendance. Sixty-five high school students were given synopses of four different fictional films, each of which had been assigned an MPAA rating of G (approved for…

  5. Study of Photo-Conductivity in Nano-Crystalline Cadmium Telluride Thin Films

    SciTech Connect

    Mahesha, M. G.; Bangera, Kasturi V.; Shivakumar, G. K.

    2011-07-15

    Nano crystallite thin films of Cadmium Telluride have been grown on glass substrates by thermal evaporation under vacuum. The growth conditions to get stoichiometric films of the compound have been optimized. The effect of substrate temperature and annealing on photosensitivity has been investigated. Also the effect of deposition parameters and post deposition annealing on rise time and decay time have been studied in detail.

  6. Highly ordered thin films of polyheterocycles: A synchrotron radiation study of polypyrrole and polythiophene Langmuir-Blodgett films

    SciTech Connect

    Skotheim, T.A.; Yang, X.Q.; Chen, J.; Hale, P.D.; Inagaki, T.; Samuelson, L.; Tripathy, S.; Hong, K.; Rubner, M.F.; den Boer, M.L.

    1988-01-01

    Langmuir-Blodgett films have been made with 3-n-hexadecylpyrrole and 3-n-octadecylpyrrole monomers and copolymers with unsubstituted pyrrole made by chemical polymerization at the air-water interface on a subphase containing FeCl/sub 3/. Langmuir-Blodgett films consisting of mixtures of stearic acid and alkylsubstituted polythiophenes have also been made as bilayer films. The orientation of single and multilayer films on platinum substrates have been studied by Near Edge X-ray Absorption Fine Structure Spectroscopy which also gives information about charge transfer interactions between the aromatic groups and the metallic substrates. The alkylsubstituted pyrroles form highly ordered two-dimensional structures. FeCl/sub 3/ initiated copolymerization with unsubstituted pyrrole leads to a more disordered system. In the case of polythiophene-stearic acid bilayers, the stearic acid layers are highly ordered. The poly(alkyl thiophene) layers sandwiched between stearic acid layers, on the other hand, exhibit random orientation of the thiophene moieties. 15 refs., 3 figs., 3 tabs.

  7. Size effect study of thin film hardness using AFM nano-indentation

    NASA Astrophysics Data System (ADS)

    Xu, Linyan; Qian, Shuangbei; Li, Juan; Liu, Congcong; Guo, Shijia; Huang, Di; Wu, Sen; Hu, Xiaodong

    2015-10-01

    With nano-level spatial and force resolution, atomic force microscope (AFM) becomes an indispensable nanoindentation measurement instrument for thin films and soft films. To do the research of size effect of the hardness property of thin films, indentation experiments have been done on a gold film with 200 nm thickness and a silicon nitride film with 110 nm thickness. It is possible to change the maximum load forces to get discrete residual depths on the film samples. The contact depths of the gold film are 15.91 nm and 26.67 nm respectively, while the contact depths of the silicon nitride film are 7.82 nm and 10.25 nm respectively. A group of nanoindentation force curves are recorded for the transformation into force-depth curves. Subsequently, a 3D image of the residual indentation can be obtained by in-situ scanning immediately after nanoindentation. The topography data is imported into a Matlab program to estimate the contact area of the indentation. For the gold film, the hardness parameters of 3.31 GPa and 2.57 GPa are calculated under the above two contact depths. And for silicon nitride film, the corresponding results are 6.51GPa and 3.58 GPa. The experimental results illustrate a strong size effect for thin film hardness. The correction of the residual indentation image of the gold film is also done as an initial study. Blind tip reconstruction (BTR) algorithm is introduced to calibrate the tip shape, and more reliable hardness values of 1.15 GPa and 0.94 GPa are estimated.

  8. Hydroxyapatite thin films grown by pulsed laser deposition and radio-frequency magnetron sputtering: comparative study

    NASA Astrophysics Data System (ADS)

    Nelea, V.; Morosanu, C.; Iliescu, M.; Mihailescu, I. N.

    2004-04-01

    Hydroxyapatite (HA) thin films for applications in the biomedical field were grown by pulsed laser deposition (PLD) and radio-frequency magnetron sputtering (RF-MS) techniques. The depositions were performed from pure hydroxyapatite targets on Ti-5Al-2.5Fe (TiAlFe) alloys substrates. In order to prevent the HA film penetration by Ti atoms or ions diffused from the Ti-based alloy during and after deposition, the substrates were pre-coated with a thin buffer layer of TiN. In both cases, TiN was introduced by reactive PLD from TiN targets in low-pressure N 2. The PLD films were grown in vacuum onto room temperature substrates. The RF-MS films were deposited in low-pressure argon on substrates heated at 550 °C. The initially amorphous PLD thin films were annealed at 550 °C for 1 h in ambient air in order to restore the initial crystalline structure of HA target. The thickness of the PLD and RF-MS films were ˜1 μm and ˜350 nm, respectively. All films were structurally studied by scanning electron microscopy (SEM), grazing incidence X-ray diffraction (GIXRD), energy dispersive X-ray spectrometry (EDS) and white light confocal microscopy (WLCM). The mechanical properties of the films were tested by Berkovich nano-indentation. Both PLD and RF-MS films mostly contain HA phase and exhibit good mechanical characteristics. Peaks of CaO were noticed as secondary phase in the GIXRD patterns only for RF-MS films. By its turn, the sputtered films were smoother as compared to the ones deposited by PLD (50 nm versus 250 nm average roughness). The RF-MS films were harder, more mechanically resistant and have a higher Young modulus.

  9. Comparative study of the mechanical properties of nanostructured thin films on stretchable substrates

    SciTech Connect

    Djaziri, S.; Renault, P.-O.; Le Bourhis, E.; Goudeau, Ph.; Faurie, D.; Geandier, G.; Mocuta, C.; Thiaudière, D.

    2014-09-07

    Comparative studies of the mechanical behavior between copper, tungsten, and W/Cu nanocomposite based on copper dispersoïd thin films were performed under in-situ controlled tensile equi-biaxial loadings using both synchrotron X-ray diffraction and digital image correlation techniques. The films first deform elastically with the lattice strain equal to the true strain given by digital image correlation measurements. The Cu single thin film intrinsic elastic limit of 0.27% is determined below the apparent elastic limit of W and W/Cu nanocomposite thin films, 0.30% and 0.49%, respectively. This difference is found to be driven by the existence of as-deposited residual stresses. Above the elastic limit on the lattice strain-true strain curves, we discriminate two different behaviors presumably footprints of plasticity and fracture. The Cu thin film shows a large transition domain (0.60% true strain range) to a plateau with a smooth evolution of the curve which is associated to peak broadening. In contrast, W and W/Cu nanocomposite thin films show a less smooth and reduced transition domain (0.30% true strain range) to a plateau with no peak broadening. These observations indicate that copper thin film shows some ductility while tungsten/copper nanocomposites thin films are brittle. Fracture resistance of W/Cu nanocomposite thin film is improved thanks to the high compressive residual stress and the elimination of the metastable β-W phase.

  10. Formation and dissolution of the passive film on iron studied by a light reflectance technique

    SciTech Connect

    Buechler, M.; Schmuki, P.; Boehni, H.

    1997-07-01

    The formation, growth, and dissolution of the passive film on iron in neutral and alkaline solutions was investigated using a light reflectance technique. In this study, laser light of 325 nm was used to access the amount of light absorbed in the film and to evaluate the optical absorption coefficient. After calibration, this technique allows a fast, in situ determination of the film thickness. Cyclic voltammetry and potential-step experiments with simultaneous thickness monitoring were carried out in borate buffer and in 0.1 M NaOH. For the borate buffer, anodic film formation and cathodic film dissolution are reversible, i.e., repeated anodic/cathodic cycling leads to conditions identical to the initial state. In NaOH, cathodic reduction of the film does not lead to film dissolution but to the formation of an electrochemically active layer, which does not significant contribute to the potential drop in the metal/film/electrolyte system. Hence, repeated passivation and reduction leads to successive thickening of the film, consisting of a barrier layer of constant thickness and a porous layer having increased thickness with every passivation/reduction cycle. This layer does not contribute to the passivity of iron.

  11. Growth and Etch Rate Study of Low Temperature Anodic Silicon Dioxide Thin Films

    PubMed Central

    Ashok, Akarapu; Pal, Prem

    2014-01-01

    Silicon dioxide (SiO2) thin films are most commonly used insulating films in the fabrication of silicon-based integrated circuits (ICs) and microelectromechanical systems (MEMS). Several techniques with different processing environments have been investigated to deposit silicon dioxide films at temperatures down to room temperature. Anodic oxidation of silicon is one of the low temperature processes to grow oxide films even below room temperature. In the present work, uniform silicon dioxide thin films are grown at room temperature by using anodic oxidation technique. Oxide films are synthesized in potentiostatic and potentiodynamic regimes at large applied voltages in order to investigate the effect of voltage, mechanical stirring of electrolyte, current density and the water percentage on growth rate, and the different properties of as-grown oxide films. Ellipsometry, FTIR, and SEM are employed to investigate various properties of the oxide films. A 5.25 Å/V growth rate is achieved in potentiostatic mode. In the case of potentiodynamic mode, 160 nm thickness is attained at 300 V. The oxide films developed in both modes are slightly silicon rich, uniform, and less porous. The present study is intended to inspect various properties which are considered for applications in MEMS and Microelectronics. PMID:24672287

  12. Experimental Study of Vane Heat Transfer and Film Cooling at Elevated Levels of Turbulence

    NASA Technical Reports Server (NTRS)

    Ames, Forrest E.

    1996-01-01

    This report documents the results of an experimental study on the influence of high level turbulence on vane film cooling and the influence of film cooling on vane heat transfer. Three different cooling configurations were investigated which included one row of film cooling on both pressure and suction surfaces, two staggered rows of film cooling on both suction and pressure surfaces, and a shower-head cooling array. The turbulence had a strong influence on film cooling effectiveness, particularly on the pressure surface where local turbulence levels were the highest. For the single row of holes, the spanwise mixing quickly reduced centerline effectiveness levels while mixing in the normal direction was more gradual. The film cooling had a strong influence on the heat transfer in the laminar regions of the vane. The effect of film cooling on heat transfer was noticeable in the turbulent regions but augmentation ratios were significantly lower. In addition to heat transfer and film cooling, velocity profiles were taken downstream of the film cooling rows at three spanwise locations. These profile comparisons documented the strong spanwise mixing due to the high turbulence. Total pressure exit measurements were also documented for the three configurations.

  13. Structural Study And Optical Properties Of TiO{sub 2} Thin Films Elaborated By Thermal Oxidation Of RF Magnetron Sputtered Ti Films

    SciTech Connect

    Guitoume, D.; Achour, S.; Guittoum, A.; Abaidia, S. E. H.

    2008-09-23

    We report on the effect of thickness on the structural and optical properties of TiO{sub 2} thin films obtained by direct exposure of Ti metal film to thermal oxidation. Ti thin films with thicknesses ranging from 87 nm to 484 nm were deposited onto glass substrate by RF magnetron sputtering. Thereafter, the as-deposited Ti films were annealed in air at temperature equal to 520 deg. C. The structural evolution and optical properties of obtained TiO{sub 2} films were studied by means of Rutherford backscattering spectrometry (RBS), grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM) and UV-Visible spectroscopy. The films thicknesses were extracted from RBS spectra. From X-ray diffraction spectra, we can see that all the films present three TiO{sub 2} phases (anatase, rutile and Brookite). The anatase and rutile phases exhibit a strong preferred orientation along (004) and (210) planes respectively. The grain sizes, D (nm), did not change much with increasing thickness. The average value of (nm) was equal to 29 nm for anatase and 26 nm for rutile. The micrographs taken from SEM experiments indicate that the films present a dense micro structure with very small grains. Transmittance spectra show that all the films present a good transparency in the visible region. The dependence of transmittance, optical band gap and refractive index on the thickness of the films was also studied.

  14. A study on various fabrication routes for preparing multilayered cubic boron nitride films and sp(3)-like boron nitride films

    NASA Astrophysics Data System (ADS)

    Wong, Sing Fai

    Cubic boron nitride (cBN) has a sp3-bonded structure which leads to excellent mechanical properties. Though cBN-rich films have been successfully fabricated by many techniques, the adhesion of the films is still unsatisfactory due to the high stresses. The maximum sustainable thickness of cBN-rich films with good adhesion is widely reported to be around 200 nm, so many practical applications of cBN coatings are hindered. In this study, we designed a series of deposition schemes in a logical sequence, in order to explore whether stress can be released, or other structural forms of BN with potential applications can be made, and to gain more fundamental understanding on the growth mechanisms of various phases observed in the films. Various fabrication processes were employed according to the following sequence: (1) A single-step process. It was showed that the maximum tolerable thickness of the cBN-rich films prepared by our system (183nm) was compatible with the result in literatures (200nm). (2) A multilayered deposition process. A thick sp2-bonded boron nitride (sP2-BN) buffer layer which was relatively deformable was added, and hence some stresses were released so as to allow a 643nm-thick, 87vol.% cBN-rich layer with acceptable adhesion to grow on top. (3) An advanced multilayer process with subsequent annealing process. A zirconium layer was pre-deposited to remove the soft buffer layer after postannealing. The interface could be strengthened as the zirconium-boride/nitride was formed. (4) Ion assist deposition at unheated condition. Composite BN films containing sp3 nanoclusters embedded in a sp2-BN matrix were fabricated. The IR technique was not sensitive enough to detect spa nanoclusters, but their presence was verified by the results of other measurements. In particular, the sp3 content can be over 30vo1.%, with a hardness 20GPa. The influences of the assist beam energy and substrate temperature on the generation of the sp3 nanoclusters were investigated

  15. a Study of Diamond Thin Film and Diamondlike Carbon Film Deposition Using Electron Cyclotron Resonance Microwave Discharges

    NASA Astrophysics Data System (ADS)

    Kuo, Szu-Cherng

    1991-02-01

    The electron cyclotron resonance (ECR) plasma is very useful for thin film technologies since it enables: (1) generation of a very dense plasma with n_ {rm e} > 10 ^{11}/cm^3 at f = 2.45 GHz; (2) generation of a highly ionized plasma (ionization degree > 1%); (3) generation of a plasma in the low pressure regime (10^ {-4} - 10^{-2} Torr); (4) generation of a radically homogeneous plasma column with large diameters; and (5) acceleration of the plasma in an inhomogeneous magnetic field. A large variety of deposition techniques have been used to prepare diamond thin films and diamondlike carbon (DLC) films. ECR plasma-assisted chemical vapor deposition (PACVD) is a new technique currently receiving much interest. The ECR plasma system offers a more complex parameter space than the more conventional PACVD processes. These include magnetic confinement of the plasma, independent source control over the dissociation of reaction gases, independent substrate bias of DC or RF voltage, independent substrate temperature control, downstream plasma operation and the magnetic mirror configuration which allows for the extraction of specific ion energies from the plasma chamber. In this work we have set up an ECR plasma-assisted materials processing system. A Lisitano coil is used to effectively couple microwave energy into the plasma, and a divergent magnetic field configuration is used to push the plasma out of the Lisitano coil. Langmuir probe measurements and optical emission spectroscopy were performed to characterize the ECR plasma. We have deposited hard DLC films on silicon substrates using this ECR plasma system. The deposition was operated at a -200 V DC bias, substrate temperature T = 200^circC, pressure P= 5*10^{-4} Torr using CH _4 as the reaction gas. The diamond thin film deposition using ECR PACVD technique has produced some initial results. Further studies into the effects of dense ion flux in the ECR plasma on diamond formation is needed.

  16. Impedance Spectroscopy Study of Composite Thin Films of Hydrated Polyethylene Glycol

    SciTech Connect

    Al-Hamarneh, Ibrahim F.; Pedrow, Patrick D.; Goheen, Steven C.; Hartenstine, M. J.

    2007-05-01

    A polythelene glycol (PEG) polymer was synthesized using a dip coating procedure on 316L stainless steel (SS) substrate pre coated by radio frequency RF inductively coupled plasma polymerization with di (ethylene glycol) vinyl ether (EO2V) monomer that was used as a primer coat. The primer and PEG composite film was studied with profilometer, visible-light microscope, scanning electron microscope (SEM) and a tape test to evaluate thickness, stability, morphology and adhesion. Response of the PEG composite film to an AC electric perturbation was studied as a function of hydration state using impedance spectroscopy (IS). A resistor/capacitor network was used to interpret the impedance spectra. The capacitance of the PEG film decreased with an exponentially decaying term as dehydration progressed. PEG film capacitance decay was consistent with a model describing water molecules diffusing through the PEG film.

  17. Impedance Spectroscopy Study of Composite Thin Films of Hydrated Polyethylene Glycol

    SciTech Connect

    Al-Hamarneh, Ibrahim F.; Pedrow, Patrick D.; Goheen, Steven C.; Hartenstine, M. J.

    2007-10-01

    A polyethylene glycol (PEG) polymer was synthesized using a dip coating procedure on 316L stainless steel (SS) substrate pre-coated with a primer that consisted of radio frequency RF inductively coupled plasma-polymerized di (ethylene glycol) vinyl ether (EO2V). The primer and PEG composite film was studied with profilometer, optical microscope, scanning electron microscope (SEM), and a tape test to evaluate thickness, coverage, morphology, and adhesion, respectively. Response of the PEG composite film to an applied AC voltage was studied as a function of hydration state using impedance spectroscopy (IS). A resistor/capacitor network was used to interpret the impedance spectra. Electrical capacitance of the PEG film decreased with an exponentially decaying term as dehydration progressed. PEG film capacitance decay was consistent with a model describing water molecules diffusing through the PEG film.

  18. Structural phase study in un-patterned and patterned PVDF semi-crystalline films

    SciTech Connect

    Pramod, K. Gangineni, Ramesh Babu

    2014-04-24

    This work explores the structural phase studies of organic polymer- polyvinylidene fluoride (PVDF) thin films in semi-crystallized phase and nano-patterned PVDF thin films. The nanopatterns are transferred with the CD layer as a master using soft lithography technique. The semi-crystalline PVDF films were prepared by a still and hot (SH) method, using a homemade spin coater that has the proficiency of substrate heating by a halogen lamp. Using this set up, smooth PVDF thin films in semi-crystalline α-phase were prepared using 2-Butanone as solvent. XRD, AFM and confocal Raman microscope have been utilized to study the structural phase, crystallinity and quality of the films.

  19. Structural phase study in un-patterned & patterned PVDF semi-crystalline films

    NASA Astrophysics Data System (ADS)

    Pramod, K.; Gangineni, Ramesh Babu

    2014-04-01

    This work explores the structural phase studies of organic polymer- polyvinylidene fluoride (PVDF) thin films in semi-crystallized phase and nano-patterned PVDF thin films. The nanopatterns are transferred with the CD layer as a master using soft lithography technique. The semi-crystalline PVDF films were prepared by a still and hot (SH) method, using a homemade spin coater that has the proficiency of substrate heating by a halogen lamp. Using this set up, smooth PVDF thin films in semi-crystalline α-phase were prepared using 2-Butanone as solvent. XRD, AFM & confocal Raman microscope have been utilized to study the structural phase, crystallinity and quality of the films.

  20. Transport studies on La0.8-xPr0.2SrxMnO3 manganite films

    NASA Astrophysics Data System (ADS)

    Solanki, P. S.; Doshi, R. R.; Ravalia, Ashish; Keshvani, M. J.; Pandya, Swati; Ganesan, V.; Shah, N. A.; Kuberkar, D. G.

    2015-05-01

    In this communication, we report the results of the studies on structural, microstructural, transport and magnetotransport behavior of La0.8-xPr0.2SrxMnO3 (LPSMO) (x=0.1, 0.2 and 0.3) manganite films grown on (100) single crystalline SrTiO3 (STO) substrate using low cost chemical solution deposition (CSD) method. Films with similar compositions were also grown using sophisticated pulsed laser deposition (PLD) technique and results of structural and transport studies obtained for CSD grown films were compared with PLD grown films. Structural studies show that all the CSD and PLD grown films possess single crystalline nature with compressive and tensile strain, respectively. Surface morphology, studied using atomic force microscope (AFM), reveals the island like grain morphology in CSD grown films while PLD grown films possess smooth film surfaces. Carrier density dependent transport properties of the films have been discussed in the context of zener double exchange (ZDE) mechanism. Lower resistivity and higher transition temperature (TP) observed in CSD grown films as compared to PLD grown films have been discussed in the light of structural strain and surface morphology of the films. Various models and mechanisms have been employed to understand the charge transport in CSD and PLD grown films. Also, observation of low temperature resistivity minima behavior in all the CSD and PLD grown LPSMO films has been explained in the context of electron-electron scattering mechanism.

  1. Polyvinyl chloride meat-wrapping film study. Final report

    SciTech Connect

    Vandervort, R.

    1988-01-01

    As a result of worker complaints in the Baltimore, Maryland area, potential health hazards associated with the use of polyvinyl-chloride film for wrapping meat were reviewed. Fumes generated during the meat-wrapping process were causing concern among the workers as they experienced respiratory irritation and distress. It appeared that only some of the meat wrappers experienced difficulty, only some of the rolls of film-produced irritations in the affected workers, and affected workers had prior histories of respiratory difficulties. Fumes were generated during hot-wire film cutting. The amount of fume generated depended significantly on the care taken during the operation. If the dispensing machines were improperly adjusted, large amounts of fumes could be obtained during the cutting process. The author concludes that the amounts of these chemicals released during this operation does not constitute a health hazard to the employees. It may be necessary, however, to remove persons with prior respiratory irritation from this particular job location.

  2. Corrosion inhibitor film formation studied by ATR-FTIR

    SciTech Connect

    Campbell, S.; Jovancicevic, V.

    1999-11-01

    The development of an inhibitor film is essential for the effective performance of a corrosion inhibitor. The use of attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR) allows the development of inhibitor films on iron oxides to be monitored. For two distinct corrosion inhibitor chemistries, oleic imidazoline and phosphate ester, the film formation and corrosion processes are monitored on Fe{sub 3}O{sub 4} in a powdered form (a model surface). Additional data following on the physical and chemical properties are obtained using XPS and SEM techniques, which allows for a more complete characterization of the model inhibitor/oxide system. By the proper choice of system and measurement techniques, the complex phenomenon of corrosion inhibition may be analyzed directly.

  3. Polytetrafluoroethylene transfer film studied with X-ray photoelectron spectroscopy

    NASA Technical Reports Server (NTRS)

    Wheeler, D. R.

    1980-01-01

    Polytetrafluoroethylene (PTFE) was rubbed against nickel in ultrahigh vacuum at loads up to 3.9 N and speeds up to 94 mm/sec. The transfer film formed on the nickel was analyzed using X-ray phototectron spectroscopy. The film was indistinguishable from bulk PTFE except for the possible presence of a small amount of NiF2. The transfer film was found to be about 1 molecule (0.5 nm) thick under all conditions; but at speeds above 10 mm/sec, there was evidence of bulk transfer in the form of fragments as well. The thickness measurements required a choice among conflicting published values of the inelastic mean free path for electrons in polymers. The values chosen gave internally consistent results.

  4. Nonlinear Optical Properties of Organic and Polymeric Thin Film Materials of Potential for Microgravity Processing Studies

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin; Frazier, Donald O.; Paley, Mark S.; Penn, Benjamin; Witherow, William K.; Bank, Curtis; Shields, Angela; Hicks, Rosline; Ashley, Paul R.

    1996-01-01

    In this paper, we will take a closer look at the state of the art of polydiacetylene, and metal-free phthalocyanine films, in view of the microgravity impact on their optical properties, their nonlinear optical properties and their potential advantages for integrated optics. These materials have many attractive features with regard to their use in integrated optical circuits and optical switching. Thin films of these materials processed in microgravity environment show enhanced optical quality and better molecular alignment than those processed in unit gravity. Our studies of these materials indicate that microgravity can play a major role in integrated optics technology. Polydiacetylene films are produced by UV irradiation of monomer solution through an optical window. This novel technique of forming polydiacetylene thin films has been modified for constructing sophisticated micro-structure integrated optical patterns using a pre-programmed UV-Laser beam. Wave guiding through these thin films by the prism coupler technique has been demonstrated. The third order nonlinear parameters of these films have been evaluated. Metal-free phthalocyanine films of good optical quality are processed in our laboratories by vapor deposition technique. Initial studies on these films indicate that they have excellent chemical, laser, and environmental stability. They have large nonlinear optical parameters and show intrinsic optical bistability. This bistability is essential for optical logic gates and optical switching applications. Waveguiding and device making investigations of these materials are underway.

  5. NEXAFS Study of Air Oxidation for Mg Nanoparticle Thin Film

    NASA Astrophysics Data System (ADS)

    Ogawa, S.; Murakami, S.; Shirai, K.; Nakanishi, K.; Ohta, T.; Yagi, S.

    2013-03-01

    The air oxidation reaction of Mg nanoparticle thin film has been investigated by Mg K-edge NEXAFS technique. It is revealed that MgO is formed on the Mg nanoparticle surfaces at the early stage of the air oxidation for Mg nanoparticle thin film. The simulation of NEXAFS spectrum using standard spectra indicates the existence of complex magnesium carbonates (x(MgCO3).yMg(OH2).z(H2O)) in addition to MgO at the early stage of the air oxidation.

  6. Structural, morphological and Raman studies of pulse electrosynthesised indium antimonide thin films

    NASA Astrophysics Data System (ADS)

    Singh, Joginder; Chandel, Tarun; Rajaram, P.

    2015-08-01

    InSb films deposited on fluorine doped tin oxide (FTO) substrates by a pulse elctrodeposition technique. The deposition was carried out at an applied potential -1.3V versus Ag/AgCl electrode. Structural, morphological and optical studies were performed on the electrodeposited InSb. X-ray diffraction (XRD) studies show that the deposited InSb films are polycrystalline in nature having the zinc blend structure. The crystallite size (D), dislocation density (δ) and strain (ɛ) were calculated using XRD results. The EDAX analysis shows that chemical composition of In3+ and Sb3+ ions is close to the required stoichiometry. The surface morphology of the deposited films was examined using scanning electron scanning electron microscopy (SEM). SEM studies reveal that the surface of the films is uniformly covered with submicron sized spherical particles. However, the crystallite size determined by the Scherrer method shows a size close to 30 nm. Surface morphology studies of the InSb films were also performed using atomic force microscopy (AFM). The average surface roughness as measured by AFM is around 40 nm. Hot probe studies show that all the electrodeposited thin films have n type conductivity and the thickness of the films is calculated using electrochemical formula.

  7. Structural, morphological and Raman studies of pulse electrosynthesised indium antimonide thin films

    SciTech Connect

    Singh, Joginder Chandel, Tarun; Rajaram, P.

    2015-08-28

    InSb films deposited on fluorine doped tin oxide (FTO) substrates by a pulse elctrodeposition technique. The deposition was carried out at an applied potential −1.3V versus Ag/AgCl electrode. Structural, morphological and optical studies were performed on the electrodeposited InSb. X-ray diffraction (XRD) studies show that the deposited InSb films are polycrystalline in nature having the zinc blend structure. The crystallite size (D), dislocation density (δ) and strain (ε) were calculated using XRD results. The EDAX analysis shows that chemical composition of In{sup 3+} and Sb{sup 3+} ions is close to the required stoichiometry. The surface morphology of the deposited films was examined using scanning electron microscopy (SEM). SEM studies reveal that the surface of the films is uniformly covered with submicron sized spherical particles. However, the crystallite size determined by the Scherrer method shows a size close to 30 nm. Surface morphology studies of the InSb films were also performed using atomic force microscopy (AFM). The average surface roughness as measured by AFM is around 40 nm. Hot probe studies show that all the electrodeposited thin films have n type conductivity and the thickness of the films is calculated using electrochemical formula.

  8. Surface film effects on drop tube undercooling studies

    NASA Technical Reports Server (NTRS)

    Ethridge, E. C.; Kaukler, W. F.

    1986-01-01

    The effects of various gaseous atmospheric constituents on drop-tube solidified samples of elemental metals were examined from a microstructural standpoint. All specimens were prepared from the purest available elements, so effects of impurities should not account for the observed effects. The drop-tube gas has a definite effect on the sample microstructure. Most dramatically, the sample cooling rate is effected. Some samples receive sufficient cooling to solidify in free fall while others do not, splating at the end of the drop tube in the sample catcher. Gases are selectively absorbed into the sample. Upon solidification gas can become less soluble and as a result forms voids within the sample. The general oxidation/reduction characteristics of the gas also affect sample microstructures. In general, under the more favorable experimental conditions including reducing atmospheric conditions and superheatings, examination of sample microstructures indicates that nucleation has been suppressed. This is indicated by underlying uniform dendrite spacings throughout the sample and with a single dendrite orientation through most of the sample. The samples were annealed yielding a few large grains and single or bi-crystal samples were commonly formed. This was especially true of samples that were inadvertently greatly superheated. This is in contrast with results from a previous study in which surface oxides were stable and contained numerous sites of nucleation. The number of nucleation events depends upon the surface state of the specimen as determined by the atmosphere and is consistent with theoretical expectations based upon the thermodynamic stability of surface oxide films. Oxide-free specimens are characterized by shiny surfaces, with no observable features under the scanning electron microscope at 5000X.

  9. X-Ray Studies of Thin Films and Interfaces.

    NASA Astrophysics Data System (ADS)

    Woronick, Steven Charles

    1990-01-01

    Presented here are a series of x-ray studies utilizing synchrotron radiation to investigate a variety of properties of thin films and interfaces in technologically important materials. By far the largest part of this dissertation is devoted to studies of x-ray reflectivity as a function of angle (mainly soft x rays), although some extended x -ray absorption fine structure (EXAFS) results are included as reprinted published papers (briefly discussed). The reflectivity discussion covers theory, experimental techniques, data analysis (by curve-fitting), and specific applications. The material systems studied by the x-ray reflectivity technique include: bulk silicon, GaAs, InAs, ~250 -A InAs layers deposited by molecular-beam epitaxy (MBE) on GaAs(100) substrates, four thicknesses (~ 126-1100 A) of SiO_2 /Si(100) produced by dry thermal oxidation, and ~250-A layers of CoSi_2 /Si(111) (two samples, one produced by MBE and one by solid-phase epitaxy). Results determined from the reflectivity measurements include: interfacial roughness parameters, refractive index of materials (in the energy range ~400-1100 eV), and overlayer thicknesses. It has been found for example that the indium -stabilized growth mode of InAs on GaAs(100) results in a smoother buried interface than the arsenic-stabilized growth mode, while the indium-stabilized growth mode on 2^circ-off GaAs(100) produces the smoothest buried interface (with typical roughness parameters in the range 10-19 A). Preliminary results indicate that growth of CoSi_2/Si(111) by MBE produces smoother buried interfaces than growth by solid-phase epitaxy. The roughness parameters have been explained in terms of growth conditions, lattice mismatch, and material inhomogeneity in the vicinity of the buried interface. The oxygen atomic scattering factor for photons in the range 400-800 eV (oxygen K edge ~ 540 eV) has also been deduced from a determination the Si and SiO_2 refractive indices. The EXAFS studies were used to

  10. A study on the magnetic behavior of Nd-Fe-B/α-Fe nanocomposite films

    NASA Astrophysics Data System (ADS)

    Madeswaran, S.; Tamano, S.; Goto, S.; Tokiwa, K.

    2010-06-01

    Nanocomposite Nd-Fe-B / α-Fe thin films were prepared by sputtering successively a Nd-rich Nd21Fe64B15 and a Fe targets in a multilayer structure using radio frequency (RF) magnetron gun. We have studied the influence of thickness of α-Fe layer on the magnetic properties of Nd-Fe-B / α-Fe thin films. A nanocomposite thin film with 15nm thick α-Fe layer prepared on 550°C heated substrate gives the highest energy product, 190 kJ/m3 along with a coercivity of 950 kA/m. Magnetic hysteresis loop measurement shows that the hard (Nd-Fe-B) and soft (α-Fe) layers are exchange coupled firmly for the films deposited on heated substrate whereas the two layers are decoupled for room temperature deposited and post annealed films.

  11. Influence of Ligands on the Formation of Kesterite Thin Films for Solar Cells: A Comparative Study.

    PubMed

    Huang, Tang Jiao; Yin, Xuesong; Tang, Chunhua; Qi, Guojun; Gong, Hao

    2016-05-10

    The preparation of solar-cell-grade Cu2 ZnSnS4 (CZTS) thin films from ligand-capped small-grained CZTS particles remains hindered by problems of phase segregation, composition non-uniformity, and in particular carbon-layer formation. Herein, through a systematic comparative study of annealed films of CZTS nanocrystals prepared using conventional oleylamine and those prepared using formamide, these problems are found to be mainly attributable to the influence of the ligands, and mechanisms are proposed. Importantly, the origin of the carbon layer in oleylamine-capped CZTS films is revealed to be the reaction between oleylamine and sulfur. This carbon layer has a very poor electrical conductivity, which can be the reason for the limited performance of such films. Fortunately, these problems can almost all be avoided by replacing oleylamine with formamide to form CZTS films. PMID:27059551

  12. Photocatalytic activity and reusability study of nanocrystalline TiO2 films prepared by sputtering technique

    NASA Astrophysics Data System (ADS)

    Barrocas, B.; Monteiro, O. C.; Jorge, M. E. Melo; Sério, S.

    2013-01-01

    The photocatalytic activity of nanocrystalline titanium dioxide (TiO2) films deposited on unheated glass substrates by DC reactive magnetron sputtering at different oxygen partial pressures was tested on the decolorization of Rhodamine 6G (Rh6G) aqueous solutions. The dye photodecolorization process was studied considering the influence of the crystallinity and preferred orientation of growth of the prepared films. It was found that the higher photocatalytic activity was achieved by the film with preferred orientation of growth along the (1 0 1) crystal direction and showing a vestigial rutile phase in a mainly anatase phase. The recycling catalytic ability of the TiO2 films was also evaluated and a promising photocatalytic performance has been revealed with a very low variation of the decay rate after five consecutive usages. Structural and morphological characterization revealed high photochemical stability of the films after successive photodegradations assays.

  13. A comparison study of textural features between FFDM and film mammogram images

    NASA Astrophysics Data System (ADS)

    Jing, Hao; Yang, Yongyi; Wernick, Miles N.; Yarusso, Laura M.; Nishikawa, Robert M.

    2011-03-01

    In this work, we conducted an imaging study to make a direct, quantitative comparison of image features measured by film and full-field digital mammography (FFDM). We acquired images of cadaver breast specimens containing simulated microcalcifications using both a GE digital mammography system and a screen-film system. To quantify the image features, we calculated and compared a set of 12 texture features derived from spatial gray-level dependence matrices. Our results demonstrate that there is a great degree of agreement between film and FFDM, with the correlation coefficient of the feature vector (formed by the 12 textural features) being 0.9569 between the two; in addition, a paired sign test reveals no significant difference between film and FFDM features. These results indicate that textural features may be interchangeable between film and FFDM for CAD algorithms.

  14. Uranium dioxide films with xenon filled bubbles for fission gas behavior studies

    NASA Astrophysics Data System (ADS)

    Usov, I. O.; Dickerson, R. M.; Dickerson, P. O.; Byler, D. D.; McClellan, K. J.

    2014-09-01

    Electron beam evaporation and ion beam assisted deposition (IBAD) methods were utilized to fabricate depleted UO2 films and UO2 films with embedded Xe atoms, respectively. The films were fabricated at elevated temperature of 700 °C and also subsequently annealed at 1000 °C to induce grain growth and Xe atom redistribution. The goal of this work was to synthesize reference UO2 samples with controlled microstructures and Xe-filled bubble morphologies, without the effects attendant to rector irradiation-induced fission. Transmission electron microscopy (TEM) microstructural characterization revealed that fine Xe-filled bubbles nucleated in the as grown films and subsequent annealing resulted in noticeable bubble size increase. Reported results demonstrate the great potential IBAD techniques and UO2 films have for various areas of nuclear materials studies.

  15. Multi-technique surface analytical studies of automotive anti-wear films

    NASA Astrophysics Data System (ADS)

    Smith, G. C.; Bell, J. C.

    1999-04-01

    A multi-technique study of model automotive anti-wear films using SEM with quantitative electron microprobe analysis, reflection-absorption IR spectroscopy, SIMS imaging and XPS depth profiling is described. Constrained simulation of the XPS depth profiles allowed model cross-sections of the film structures to be constructed. With zinc dialkyl dithiophosphate as an anti-wear additive, the anti-wear films were found to have a thin inorganic mixed sulphide/oxide layer immediately above the Fe substrate. This formed the base for a thicker Zn-containing polyphosphate-like overlayer. Addition of detergent and dispersant to the lubricant formulation resulted in thicker, more patchy films, with a clearer differentiation between film and substrate.

  16. XPS and Raman study of slope-polished Cu(In,Ga)Se2 thin films

    NASA Astrophysics Data System (ADS)

    Beak, Gun Yeol; Jeon, Chan-Wook

    2016-05-01

    The growth of quality Cu(In,Ga)Se2 photovoltaic absorber without secondary phases is very important for improving the solar cell efficiency. Although X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy can identify the secondary phases, they provide insufficient information because of their insufficient resolution and complexity in analysis. In general, normal Raman spectroscopy is better for the analysis of secondary phases. On the other hand, the Raman signal provides information for film depths of less than 300 nm, and the Raman information cannot represent the properties of the entire film. In this regard, the authors introduce a new way of identifying secondary phases in Cu(In,Ga)Se2 films using depth Raman analysis. The as-prepared film was polished using a dimple grinder, which expanded a 2 μm thick film to approximately 1 mm, which is more than sufficient to resolve the depth distribution. Raman analysis indicated that the Cu(In,Ga)Se2 film showed different secondary phases, such as CuIn3Se5, InSe and CuSe, present in different depths of the film, whereas XPS provided complex information about the phases. Overall, the present study emphasizes that the Raman depth profile is more efficient for the identification of secondary phases in Cu(In,Ga)Se2 thin films than XPS and XRD. [Figure not available: see fulltext.

  17. Structural and magnetic studies of thin Fe57 films formed by ion beam assisted deposition

    NASA Astrophysics Data System (ADS)

    Lyadov, N. M.; Bazarov, V. V.; Vagizov, F. G.; Vakhitov, I. R.; Dulov, E. N.; Kashapov, R. N.; Noskov, A. I.; Khaibullin, R. I.; Shustov, V. A.; Faizrakhmanov, I. A.

    2016-08-01

    Thin Fe57 films with the thickness of 120 nm have been prepared on glass substrates by using the ion-beam-assisted deposition technique. X-ray diffraction, electron microdiffraction and Mössbauer spectroscopy studies have shown that as-deposited films are in a stressful nanostructured state containing the nanoscaled inclusions of α-phase iron with the size of ∼10 nm. Room temperature in-plane and out-of-plane magnetization measurements confirmed the presence of the magnetic α-phase in the iron film and indicated the strong effect of residual stresses on magnetic properties of the film as well. Subsequent thermal annealing of iron films in vacuum at the temperature of 450 °C stimulates the growth of α-phase Fe crystallites with the size of up to 20 nm. However, electron microdiffraction and Mössbauer spectroscopic data have shown the partial oxidation and carbonization of the iron film during annealing. The stress disappeared after annealing of the film. The magnetic behaviour of the annealed samples was characterized by the magnetic hysteresis loop with the coercive field of ∼10 mT and the saturation magnetization decreased slightly in comparison with the α-phase Fe magnetization due to small oxidation of the film.

  18. Magnetization studies of embedded and coated thin films using Magneto-Optic Kerr Effect

    NASA Astrophysics Data System (ADS)

    Balasubramanian, Srinath

    The advancements made in electronic storage demand characterization of new materials and magnetic structures. The Magneto-Optic Kerr Effect (MOKE) is an interesting tool to characterize materials for usage in modern electronic storage devices such as magneto-optical drive, magnetic random access memory and spin valve devices. In this work, an attempt was made to characterize embedded and coated films using Magneto-Optic Kerr Effect technique. An experimental system was built for the measurement of Kerr rotation. Magnetization studies of PMMA (Poly(methyl methacrylate)) films embedded with iron nanoparticles and quartz films coated with hematite nanoparticles were carried out using MOKE. The embedded films exhibited weak magnetic response. For the coated films, the hysteresis loops were shifted from the origin indicating the presence of exchange bias in the system. Symmetric and asymmetric magnetization reversals were observed due to the presence of antiferromagnetic regions non-collinear with the external magnetic field. The samples with higher concentrations of nanoparticles showed dipolar interactions at relatively low fields. The coated films showed better magneto-optic response as compared to the embedded films. The exchange bias effects in the coated films makes it a candidate for various applications such as permanent magnets, magnetic recording media and stabilizers in recording heads.

  19. Cultural Studies of Education: Filming Fluid Subjectivities in Indonesian Universities

    ERIC Educational Resources Information Center

    Logli, Chiara

    2016-01-01

    This article focuses on the Indonesian film "Cin(T)a," which features the interfaith and multiethnic love between two college students. I apply intergroup contact theory, critical pedagogy and grounded cosmopolitanism to the reading of the movie in order to demonstrate two key points. First, higher education is a contact zone, where…

  20. Optical interferometry study of film formation in lubrication of sliding and/or rolling contacts

    NASA Technical Reports Server (NTRS)

    Stejskal, E. O.; Cameron, A.

    1972-01-01

    Seventeen fluids of widely varying physical properties and molecular structure were chosen for study. Film thickness and traction were measured simultaneously in point contacts by interferometry, from which a new theory of traction was proposed. Film thickness was measured in line contacts by interferometry and electrical capacitance to establish correlation between these two methods. An interferometric method for the absolute determination of refractive index in the contact zone was developed and applied to point contact fluid entrapments. Electrical capacitance was used to study the thickness and properties of the soft surface film which sometimes forms near a metal-fluid interface.

  1. Holographic characterization of DYE-PVA films studied at 442 nm for optical elements fabrication

    NASA Astrophysics Data System (ADS)

    Couture, Jean J.

    1991-12-01

    The present work is an experimental study of the speed of hologram recording in dichromated polyvinyl alcohol films (DC-PVA) and DYE-DC-PVA films. Real-time recordings give high diffraction efficiency and low signal-to-noise ratio holograms without any chemical development. The dyes studied here are MALACHITE GREEN, EOSIN Y, and ROSE BENGAL introduced in DC-PVA films having a thickness of 60 - 62 micrometers . The best of these DYE-DC-PVA systems is a good candidate for holographic optical elements fabrication.

  2. Spectroscopic Ellipsometry Studies of Ag and ZnO Thin Films and Their Interfaces for Thin Film Photovoltaics

    NASA Astrophysics Data System (ADS)

    Sainju, Deepak

    Many modern optical and electronic devices, including photovoltaic devices, consist of multilayered thin film structures. Spectroscopic ellipsometry (SE) is a critically important characterization technique for such multilayers. SE can be applied to measure key parameters related to the structural, optical, and electrical properties of the components of multilayers with high accuracy and precision. One of the key advantages of this non-destructive technique is its capability of monitoring the growth dynamics of thin films in-situ and in real time with monolayer level precision. In this dissertation, the techniques of SE have been applied to study the component layer materials and structures used as back-reflectors and as the transparent contact layers in thin film photovoltaic technologies, including hydrogenated silicon (Si:H), copper indium-gallium diselenide (CIGS), and cadmium telluride (CdTe). The component layer materials, including silver and both intrinsic and doped zinc oxide, are fabricated on crystalline silicon and glass substrates using magnetron sputtering techniques. These thin films are measured in-situ and in real time as well as ex-situ by spectroscopic ellipsometry in order to extract parameters related to the structural properties, such as bulk layer thickness and surface roughness layer thickness and their time evolution, the latter information specific to real time measurements. The index of refraction and extinction coefficient or complex dielectric function of a single unknown layer can also be obtained from the measurement versus photon energy. Applying analytical expressions for these optical properties versus photon energy, parameters that describe electronic transport, such as electrical resistivity and electron scattering time, can be extracted. The SE technique is also performed as the sample is heated in order to derive the effects of annealing on the optical properties and derived electrical transport parameters, as well as the

  3. Hexametaphosphate effects on tooth surface conditioning film chemistry--in vitro and in vivo studies.

    PubMed

    Busscher, Henk J; White, Donald J; van der Mei, Henny C; Baig, Arif A; Kozak, Kathy M

    2002-01-01

    These studies compared the effects of Crest Dual Action Whitening dentifrice with sodium hexametaphosphate and control commercial dentifrices on the surface chemistry of conditioning film-coated dental enamel in vitro and in vivo. Conditioning film chemistry was studied by measurements of film thickness, ability to wet the surface/surface energy, conditioning film chemical composition and zeta potential. Laboratory and in vivo studies demonstrated that brushing and chemical-only treatment of pellicle-coated enamel surfaces produced marked changes in surface chemistry. Brushing of surfaces with all commercial dentifrices significantly reduced pellicle film quantity. Effects on non-brushed areas, of significance in the clinical situation, were different for different dentifrices. For dentifrice chemical treatments, calcium phosphate surface active builders, such as pyrophosphate and hexametaphosphate, produced stronger effects than standard (non-tartar control) dentifrices, peroxide baking soda dentifrices and dentifrices formulated with carboxylate polymers, viz. Colgate Total with copolymer. Crest Dual Action Whitening hexametaphosphate dentifrice removed more pellicle conditioning film, produced a lower zeta potential, produced the largest changes in film composition and had the greatest impact on surface free energies of the tested dentifrices. Crest Dual Action Whitening dentifrice also produced lasting changes in the reacquisition of pellicle conditioning film, as established by in vitro cycling immersion studies. Crest Dual Action Whitening dentifrice produced stronger and more lasting effects on surface film chemistry than low molecular weight pyrophosphate (Crest Tartar Control) or other polymeric-based dentifrice systems (Colgate Total). These surface chemistries may contribute to the unique clinical actions of hexametaphosphate established in recently reported, randomized clinical studies of tartar control, stain prevention and stain removal effects. PMID

  4. Swelling, ion uptake and biodegradation studies of PE film modified through radiation induced graft copolymerization

    NASA Astrophysics Data System (ADS)

    Kaur, Inderjeet; Gupta, Nitika; Kumari, Vandna

    2011-09-01

    An attempt to develop biodegradable polyethylene film grafting of mixture of hydrophilic monomers methacrylic acid (MAAc) and acrylamide (AAm) onto PE film has been carried out by preirradiation method using benzoyl peroxide as the radical initiator. Since ether linkages are susceptible to easy cleavage during degradation process, PE film was irradiated before the grafting reactions by γ-rays to introduce peroxidic linkages (PE-OO-PE) that offer sites for grafting. The effect of irradiation dose, monomer concentration, initiator concentration, temperature, time and amount of water on the grafting percent was determined. Maximum percentage of grafting of binary mixture (MAAc+AAm), (1792%) was obtained at a total concentration of binary monomer mixture=204.6×10 -2 mol/L ([MAAc]=176.5×10 -2 mol/L, [AAm]=28.1×10 -2 mol/L), [BPO]=8.3×10 -2 mol/L at 100 °C in 70 min. The grafted PE film was characterized by the Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopic (SEM) methods. Some selective properties of grafted films such as swelling studies, ion uptake and biodegradation studies have been investigated. The grafted films show good swelling in water, ion uptake studies shows promising results for desalination of brackish water and the soil burial test shows that PE film grafted with binary monomer mixture degrades up to 47% within 50 days.

  5. Vibrational studies of molecular organization in evaporated phthalocyanine thin solid films

    SciTech Connect

    Aroca, R.; Thedchanamoorthy, A.

    1995-01-01

    This report presents results on the study of the molecular organization, utilizing transmission and reflection absorption FTIR spectroscopy, of thin films of phthalocyanine complexes and metal free phthalocyanine. The spatial anisotropy was probed.

  6. Monte Carlo study on exchange bias and coercivity properties in coupled ferromagnetic/antiferromagnetic films

    NASA Astrophysics Data System (ADS)

    Jiang, Liqin; Shen, Shuangjuan; Zhang, Jian-Min; Feng, Qian; Huang, Zhigao

    2015-12-01

    Based on Monte Carlo simulation, a model consisting of an antiferromagnetic (AFM) film coupled to a ferromagnetic (FM) film is developed to study the exchange bias and coercivity phenomenon. It is suggested that exchange bias is a consequence of exchange coupling in the AFM/FM interface, and the AFM anisotropy needs to have a threshold value for the occurrence of exchange bias. Simultaneously, exchange bias and coercivity as functions of the value of anisotropy, exchange coupling and film thickness are studied. By inducing a thickness dependence of the anisotropy in FM film, the coercivity can be reduced or enhanced by choosing suitable magnetic parameters, which can better account for the discrepancies found in previous studies. The results also provide evidence for the absence of a direct correlation between coercivity and exchange bias, which is in agreement with other studies.

  7. Studies on RF sputtered (WO3)1-x (V2O5)x thin films for smart window applications

    NASA Astrophysics Data System (ADS)

    Meenakshi, M.; Sivakumar, R.; Perumal, P.; Sanjeeviraja, C.

    2016-05-01

    V2O5 doped WO3 targets for RF sputtering thin film deposition were prepared for various compositions. Thin films of (WO3)1-x (V2O5)x were deposited on to glass substrates using these targets. Structural characteristics of the prepared targets and thin films were studied using X-ray diffraction. Laser Raman studies were carried out on the thin films to confirm the compound formation.

  8. Laboratory studies of thin films representative of atmospheric sulfate aerosol

    NASA Astrophysics Data System (ADS)

    Fortin, Tara Jean

    Sulfate aerosols are present globally in both the upper troposphere and lower stratosphere. These aerosols are of great interest because they have a profound influence on Earth's radiation balance, heterogeneous chemistry, and cloud formation mechanisms throughout the atmosphere. The magnitude of these effects is ultimately determined by the size, phase, and chemical composition of the aerosols themselves. This thesis explores some of the questions that remain concerning the phase of these aerosols under atmospheric conditions and the effects of their chemical composition on heterogeneous chemistry and cloud formation mechanisms. In the upper troposphere, cirrus clouds are thought to form via the homogeneous nucleation of ice out of dilute sulfate aerosols such as ammonium sulfate ((NH4)2SO4). To investigate this, the low-temperature phase behavior of ammonium sulfate films has been studied using Fourier transform infrared (FTIR) spectroscopy. Experiments performed as a function of increasing relative humidity demonstrate that a phase transition from crystalline (NH 4)2SO4 to a metastable aqueous solution can occur at temperatures below the eutectic at 254 K. However, on occasion, direct deposition of ice from the vapor phase was observed, possibly indicating selective heterogeneous nucleation. In addition to serving as nuclei for cirrus clouds, sulfate aerosols can participate in heterogeneous reactions. The interaction of HNO3 with ammonium sulfate has been investigated as a possible loss mechanism for gas-phase HNO3 using a Knudsen cell reactor coupled with transmission FTIR spectroscopy. The results show that HNO3 reacts with solid ammonium sulfate to produce ammonium nitrate and letovicite at 203 K. Furthermore, this reaction is enhanced as a function of relative humidity from 0 to 41%. In the lower stratosphere, polar stratospheric clouds (PSCs) are important for springtime ozone depletion. The vapor deposition of ice on sulfuric acid tetrahydrate (SAT) has

  9. Understanding Film as Process of Change: A Metalanguage for the Study of Film Developed and Applied to Ingmar Bergman's "Persona" and Alan J. Pakula's "The Sterile Cuckoo."

    ERIC Educational Resources Information Center

    Koch, Christian Herbert

    This study develops and applies a way of talking about that transformation or change occurring in the mind of a film viewer as he views a film. This articulation is expressed in a metalanguage constructed along parameters of a game situation. The terminology employed in the articulation is derived from contemporary French structuralism and…

  10. Study of two different thin film coating methods in transmission laser micro-joining of thin Ti-film coated glass and polyimide for biomedical applications.

    PubMed

    Sultana, T; Georgiev, G L; Baird, R J; Auner, G W; Newaz, G; Patwa, R; Herfurth, H J

    2009-07-01

    Biomedical devices and implants require precision joining for hermetic sealing which can be achieved with low power lasers. The effect of two different thin metal film coating methods was studied in transmission laser micro-joints of titanium-coated glass and polyimide. The coating methods were cathodic arc physical vapor deposition (CA-PVD) and electron beam evaporation (EB-PVD). Titanium-coated glass joined to polyimide film can have neural electrode application. The improvement of the joint quality will be essential for robust performance of the device. Low power fiber laser (wave length = 1100 nm) was used for transmission laser micro-joining of thin titanium (Ti) film (approximately 200 nm) coated Pyrex borosilicate 7740 glass wafer (0.5 mm thick) and polyimide (Imidex) film (0.2 mm thick). Ti film acts as the coupling agent in the joining process. The Ti film deposition rate in the CA-PVD was 5-10 A/s and in the EB-PVD 1.5 A/s. The laser joint strength was measured by a lap shear test, the Ti film surfaces were analyzed by atomic force microscopy (AFM) and the lap shear tested joints were analyzed by optical microscopy and scanning electron microscopy (SEM). The film properties and the failure modes of the joints were correlated to joint strength. The CA-PVD produced around 4 times stronger laser joints than EB-PVD. The adhesion of the Ti film on glass by CA-PVD is better than that of the EB-PVD method. This is likely to be due to a higher film deposition rate and consequently higher adhesion or sticking coefficient for the CA-PVD particles arriving on the substrate compared to that of the EB-PVD film. EB-PVD shows poor laser bonding properties due to the development of thermal hotspots which occurs from film decohesion. PMID:19627828

  11. Channelling study of La1-xSrxCoO3 films on different substrates

    NASA Astrophysics Data System (ADS)

    Szilágyi, E.; Kótai, E.; Rata, D.; Németh, Z.; Vankó, G.

    2014-08-01

    The cobalt oxide system LaCoO3 and its Sr-doped child compounds have been intensively studied for decades due to their intriguing magnetic and electronic properties. Preparing thin La1-xSrxCoO3 (LSCO) films on different substrates allows for studies with a new type of perturbation, as the films are subject to substrate-dependent epitaxial strain. By choosing a proper substrate for a thin film grow, not only compressing but also tensile strain can be applied. The consequences for the fundamental physical properties are dramatic: while compressed films are metallic, as the bulk material, films under tensile strain become insulating. The goal of this work is to determine the strain tensor in LSCO films prepared on LaAlO3 and SrTiO3 substrates by pulsed laser deposition using RBS/channelling methods. Apart from the composition and defect structure of the samples, the depth dependence of the strain tensor, the cell parameters, and the volume of the unit cell are also determined. Asymmetric behaviour of the strained cell parameters is found on both substrates. This asymmetry is rather weak in the case of LSCO film grown on LaAlO3, while stronger on SrTiO3 substrate. The strain is more effective at the interface, some relaxation can be observed near to the surface.

  12. Studies of thin film nonlinear viscoelasticity for superpressure balloons

    NASA Astrophysics Data System (ADS)

    Rand, J. L.; Wakefield, D.

    2010-01-01

    In order to provide scientists with a stratospheric platform from which to conduct long duration research, a superpressure balloon is desired which will maintain a relatively constant volume for weeks at a time. The pumpkin shaped balloon has been developed by making use of the surface lobing to limit the circumferential stress and meridional tendons to carry the loads in the other direction. However, in order to prevent geometric instabilities during deployment and after pressurization, the design should eliminate as much excess material as possible while not exceeding the permissible stresses of the material. This paper will describe the behavior of the very thin membrane material selected for this application and the limits of the film in a biaxial state of stress. In addition, it is shown that the viscoelastic nature of the film will limit the stress by causing a reduced radius of curvature in the lobe of the pumpkin.

  13. FTIR and XRD study of PMMA/PCTFE blend films

    SciTech Connect

    Tripathi, S. Shripathi, T.; Tripathi, J.; Agrawal, A.; Sharma, A.

    2014-04-24

    The results are reported on solution cast PMMA-PCTFE blend films characterized using x-ray diffraction and FTIR. The nanocrystalline nature of PMMA is still seen in the blends, however, the bond modifications are clearly observed. The addition of PCTFE results in the modification in structural properties, as reflected in the XRD and FTIR spectra showing modifications in bonding as a function of PCTFE percentage.

  14. Deposition of hydroxyapatite thin films by Nd:YAG laser ablation: a microstructural study

    SciTech Connect

    Nistor, L.C.; Ghica, C.; Teodorescu, V.S.; Nistor, S.V. . E-mail: snistor@alpha1.infim.ro; Dinescu, M.; Matei, D.; Frangis, N.; Vouroutzis, N.; Liutas, C.

    2004-11-02

    Hydroxyapatite (HA) thin films has been successfully deposited by Nd:YAG laser ablation at {lambda} = 532 nm. The morphology and microstructure of the deposited layers was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). Polycrystalline HA films were directly obtained with the substrate at 300 deg. C and without introducing water vapors in the deposition chamber. Electron paramagnetic resonance (EPR) measurements show that the oxygen stoichiometry in the HA films is also maintained. Depositions performed at {lambda} = 335 nm laser wavelength and 300 deg. C substrate temperature resulted in polycrystalline layers of mixed composition of HA and tricalciumphosphate (TCP)

  15. Partially wetting thin liquid films: structure and dynamics studied with coherent x rays.

    PubMed

    Gutt, C; Sprung, M; Fendt, R; Madsen, A; Sinha, S K; Tolan, M

    2007-08-31

    We studied the surface structure of thin liquid films vapor deposited on solid substrates in a partial wetting situation by means of coherent x-ray scattering. No dynamics has been observed showing the absence of capillary waves on liquid films partially wetting a substrate. Instead an exponential form of the height-height correlation function has been found pointing toward a solidlike behavior of the thin liquid films at large length scales. The exact surface structure and degree of replication with the substrate depend on the deposition rate of the molecules. PMID:17931023

  16. XPS Study of Thermally Evaporated Ge-Sb-Te Amorphous Thin Films

    SciTech Connect

    Kumar, Sandeep; Singh, Digvijay; Thangaraj, R.

    2011-12-12

    Amorphous thin films were prepared from the bulk composition of Ge{sub 22}Sb{sub 22}Te{sub 56}(GST) alloy by thermal evaporation in good vacuum condition. The amorphous nature of as-deposited films was checked with x-ray diffraction (XRD) studies. X-ray photoelectron spectroscopy (XPS) has been used to determine the binding energies of the core electrons in amorphous thin GST films. In XPS, we performed the survey scan from the binding energy (BE) range from 0-1100 eV and core level spectra of Ge 3d, Sb 3d and Te 3d.

  17. A Study on the Fabrication of Organic Thin Film Transistor Sensors using Gravure Printing

    NASA Astrophysics Data System (ADS)

    Hwang, Won-Jin; Hong, Jae-Min; Ju, Byeong-Kwon; Yu, Jae-Woong

    2011-12-01

    Conducting polymer TFT was fabricated with gravure printing technique using a vapor polymerization method. Polyvinyl alcohol (PVA) with excellent film forming characteristics was used as a matrix polymer. After the printing of the oxidant dispersed PVA dissolved in DI water, the vapor polymerization of the pyrrole monomer formed a thin conducting polymer film. The conductivity of the film was dependent on the concentration of the oxidant and the polymerization time. In order to be used for TFT application, the conductivity had to be reduced by controlling the various conditions. The effect of exposure to humidity on TFT signal was studied.

  18. Phantom study of tear film dynamics with optical coherence tomography and maximum-likelihood estimation

    PubMed Central

    Huang, Jinxin; Lee, Kye-sung; Clarkson, Eric; Kupinski, Matthew; Maki, Kara L.; Ross, David S.; Aquavella, James V.; Rolland, Jannick P.

    2016-01-01

    In this Letter, we implement a maximum-likelihood estimator to interpret optical coherence tomography (OCT) data for the first time, based on Fourier-domain OCT and a two-interface tear film model. We use the root mean square error as a figure of merit to quantify the system performance of estimating the tear film thickness. With the methodology of task-based assessment, we study the trade-off between system imaging speed (temporal resolution of the dynamics) and the precision of the estimation. Finally, the estimator is validated with a digital tear-film dynamics phantom. PMID:23938923

  19. A photoemission study of Pd ultrathin films on Pt(111)

    SciTech Connect

    Mun, Bongjin Simon; Lee, Choongman; Stamenkovic, Vojislav; Markovic, Nenad M.; Ross Jr., Philip N.

    2005-05-11

    The origin of surface core-level shift (SCLS) of Pd thin films on Pt(111) substrate is investigated. At sub-monolayer coverage of Pd thin films, the splitting of Pd 3d core level peaks indicate the contribution of both initial and final-state of photo-ionization processes while there is almost no change on valence band (VB) spectra. When the coverage of Pd reaches to single monolayer, the final-state relaxation effect on the Pd 3d vanishes and only the initial-state effect, a negative SCLS, is present. Also, the VB spectrum at Pd monolayer films shows a clear band narrowing, that is the origin of the negative SCLS at monolayer coverage. As the Pd coverage is increased to more than monolayer thickness, the Pd 3d peaks start to show the surface layer contribution from second and third layers, positive SCLS, and the VB spectrum shows even narrower band width, possibly due to the formation of surface states and strained effect of Pd adlayers on top of the first pseudomorphic layer.

  20. Electrochromic performance, wettability and optical study of copper manganese oxide thin films: Effect of annealing temperature

    NASA Astrophysics Data System (ADS)

    Falahatgar, S. S.; Ghodsi, F. E.; Tepehan, F. Z.; Tepehan, G. G.; Turhan, İ.

    2014-01-01

    In the present work, the nanostructured copper manganese oxide (CMO) thin films were prepared from acetate based sol-gel precursors and deposited on glass and indium tin oxide (ITO) substrates by dip-coating technique. The films were annealed at 300, 400 and 500 °C in ambient atmosphere. The effects of annealing temperature on structural, morphological, wettability, electrochromic and optical properties of CMO thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDX), water contact angle measurement (WCA), cyclic voltammetry (CV) measurements and ultraviolet-visible (UV-vis) spectrophotometery. The presence of mixed oxide phases comprising of copper manganese oxide (CuMn2O4) and manganese oxide at different annealing temperature was confirmed by XRD patterns. The results showed that the Mn3O4 phase has been changed to Mn2O3 when the annealing temperature is increased from 300 to 500 °C. The FESEM images indicated that the granular surface morphology was sensitive to annealing temperature. EDX studies indicated that the thin films contained O, Mn and Cu species. Wettability studies showed that the water contact angle of the nanostructured CMO thin films coated on glass substrates was influenced by the variation of annealing temperature and the surface nature of thin films was changed from hydrophilic to hydrophobic. The results of CVs measurement indicated that the anodic and cathodic charge density and capacitance of all CMO samples decreased with increasing scan rate in potential range of -1-1 eV. Also, the annealed CMO thin film at 500 °C showed better electrochromic performance with respect to other samples at lower scan rate. The thickness, refractive index, extinction coefficient and optical band gap of thin films coated on glass substrates were calculated from reflectance and transmittance spectra using an iterative numerical method. The optical band gap of

  1. Transdermal film-loaded finasteride microplates to enhance drug skin permeation: Two-step optimization study.

    PubMed

    Ahmed, Tarek A; El-Say, Khalid M

    2016-06-10

    The goal was to develop an optimized transdermal finasteride (FNS) film loaded with drug microplates (MIC), utilizing two-step optimization, to decrease the dosing schedule and inconsistency in gastrointestinal absorption. First; 3-level factorial design was implemented to prepare optimized FNS-MIC of minimum particle size. Second; Box-Behnken design matrix was used to develop optimized transdermal FNS-MIC film. Interaction among MIC components was studied using physicochemical characterization tools. Film components namely; hydroxypropyl methyl cellulose (X1), dimethyl sulfoxide (X2) and propylene glycol (X3) were optimized for their effects on the film thickness (Y1) and elongation percent (Y2), and for FNS steady state flux (Y3), permeability coefficient (Y4), and diffusion coefficient (Y5) following ex-vivo permeation through the rat skin. Morphological study of the optimized MIC and transdermal film was also investigated. Results revealed that stabilizer concentration and anti-solvent percent were significantly affecting MIC formulation. Optimized FNS-MIC of particle size 0.93μm was successfully prepared in which there was no interaction observed among their components. An enhancement in the aqueous solubility of FNS-MIC by more than 23% was achieved. All the studied variables, most of their interaction and quadratic effects were significantly affecting the studied variables (Y1-Y5). Morphological observation illustrated non-spherical, short rods, flakes like small plates that were homogeneously distributed in the optimized transdermal film. Ex-vivo study showed enhanced FNS permeation from film loaded MIC when compared to that contains pure drug. So, MIC is a successful technique to enhance aqueous solubility and skin permeation of poor water soluble drug especially when loaded into transdermal films. PMID:26993962

  2. Study of the doping of thermally evaporated zinc oxide thin films with indium and indium oxide

    NASA Astrophysics Data System (ADS)

    Palimar, Sowmya; Bangera, Kasturi V.; Shivakumar, G. K.

    2013-12-01

    The present paper reports observations made on investigations carried out to study structural, optical and electrical properties of thermally evaporated ZnO thin films and their modulations on doping with metallic indium and indium oxide separately. ZnO thin film in the undoped state is found to have a very good conductivity of 90 Ω-1 cm-1 with an excellent transmittance of up to 90 % in the visible region. After doping with metallic indium, the conductivity of the film is found to be 580 Ω-1 cm-1, whereas the conductivity of indium oxide-doped films is increased up to 3.5 × 103 Ω-1 cm-1. Further, the optical band gap of the ZnO thin film is widened from 3.26 to 3.3 eV when doped with indium oxide and with metallic indium it decreases to 3.2 eV. There is no considerable change in the transmittance of the films after doping. All undoped and doped films were amorphous in nature with smooth and flat surface without significant modifications due to doping.

  3. A numerical study of liquid film distribution in wet natural gas pipelines

    NASA Astrophysics Data System (ADS)

    Gao, X. Q.; Zhao, Y. L.; Xu, W. W.; Guan, X. R.; Wang, J. J.; Jin, Y. H.

    2016-05-01

    The software of FLUENT was used to simulate the gas-liquid turbulent flow in wet natural gas pipeline of the Puguang gas field. The RNG k- ɛ model was used to simulate the turbulent flow, the Mixture model was used to simulate gas-liquid mixed phase, and the Eulerian wall film model was used to simulate the formation and development of liquid film. The gas phase flow field characteristics, the distribution of the axial and circumferential film thickness, and the droplet distribution in the pipeline were studied when the gas Reynolds number is 7.72 × 106(10.8m/s). The results can be concluded as followed: Liquid film distributes unevenly along the circumferential direction and mostly distributes under the pipeline wall because of gravity. The impact of the dean vortex and centrifugal force in the straight section can also influence the liquid film distribution. The wall shear stress distributions in horizontal straight pipeline is concerned with liquid membrane volatility, and consistent with the film volatility period, the wall shear stress reached the maximum value in a certain position of wave front. The influence of the wall shear stress on the film fluctuation in inclined pipeline is weakened by gravity and other factors.

  4. Study of Flux Ratio of C60 to Ar Cluster Ion for Hard DLC Film deposition

    SciTech Connect

    Miyauchi, K.; Toyoda, N.; Kanda, K.; Matsui, S.; Kitagawa, T.; Yamada, I.

    2003-08-26

    To study the influence of the flux ratio of C60 molecule to Ar cluster ion on (diamond like carbon) DLC film characteristics, DLC films deposited under various flux ratios were characterized with Raman spectrometry and Near Edge X-ray Absorption Fine Structure (NEXAFS). From results of these measurements, hard DLC films were deposited when the flux ratio of C60 to Ar cluster ion was between 0.7 and 4. Furthermore the DLC film with constant sp2 content was obtained in the range of the ratio from 0.7 to 4, which contents are lower values than that of conventional films such as RF plasma. DLC films deposited under the ratio from 1 to 4 had hardness from 40 to 45GPa. It was shown that DLC films with stable properties of low sp2 content and high hardness were formed even when the fluxes were varied from 1 to 4 during deposition. It was indicated that this process was useful in the view of industrial application.

  5. Fluctuation microscopy studies of medium-range ordering in amorphous diamond-like carbon films.

    SciTech Connect

    Chen, X.; Sullivan, J. P.; Friedmann, T. A.; Gibson, J. M.; Cedarville Univ.; SNL

    2004-04-12

    In this letter, we report fluctuation microscopy studies of medium-range ordering in amorphous diamond-like carbon films and the effect of annealing on this ordering. Annealed and unannealed diamond-like carbon films have almost identical short-range order. Our fluctuation microscopy results, however, indicate the presence of medium range order or clustering in the films on a lateral length scale that exceeds 1 nm. Within the clustered regions, the dominant local ordering appears to be diamond-like, and graphite-like ordering is not observed. Thermal annealing up to 600 {sup o}C leads to an increase in diamond-like clustering with no onset of graphite-like clustering. However, after high temperature annealing up to 1000 {sup o}C, graphite-like clustering becomes apparent as a result of the conversion of diamond-like carbon to graphite-like carbon. The results on the as-deposited films and films annealed up to 600 {sup o}C suggest that a spontaneous medium range ordering process occurs in diamond-like carbon films during and subsequent to film growth, and this may play an important role in stress relaxation.

  6. AN EXPERIMENTAL STUDY OF THE RELATIONSHIP OF FILM MOVEMENT AND EMOTIONAL RESPONSE, AND ITS EFFECT ON LEARNING AND ATTITUDE FORMATION.

    ERIC Educational Resources Information Center

    MILLER, WILLIAM CHARLES, III

    THIS EXPERIMENTAL STUDY EXAMINED THE HYPOTHESES THAT FILM MOTION INCREASES AUDIENCE EMOTIONAL INVOLVEMENT, INCREASES POSITIVE ATTITUDE RESPONSE TO THE FILM AND DOES NOT AFFECT AUDIENCE INFORMATION RETENTION. OTHER HYPOTHESES WERE THAT THE GALVANIC SKIN RESPONSE (GSR) IS USEFUL FOR EVALUATING FILM AUDIENCE EMOTIONAL INVOLVEMENT, THAT AUDIENCE…

  7. A Raman Study of the Origin of Oxygen Defects in Hexagonal Manganite Thin Films

    NASA Astrophysics Data System (ADS)

    Chen, Xiang-Bai; Hien Nguyen Thi, Minh; Yang, In-Sang; Lee, Daesu; Noh, Tae-Won

    2012-12-01

    Oxygen defects are usually unavoidable when synthesizing oxide thin films. We study the origin of the oxygen defects in hexagonal manganite HoMnO3 epitaxial thin films through Raman scattering spectroscopy. Our results show that the oxygen defects in hexagonal HoMnO3 thin films have distinct effects on different phonon modes and on magnon scattering. Our analyses indicate that the oxygen defects in hexagonal HoMnO3 thin films mainly originate from the basal O3 and/or O4 oxygen vacancies. Furthermore, our analyses of oxygen defects predict that the Mn 3d orbitals would be more strongly hybridized with the apical O1 and/or O2 2p orbitals than the basal O3 and/or O4 2p orbitals. This prediction is consistent with our resonant Raman scattering study and earlier first-principle calculations of the electronic structures of hexagonal manganites.

  8. Study of oxygen scavenging PET-based films activated by water

    NASA Astrophysics Data System (ADS)

    Rossi, Gabriella; Scarfato, Paola; Incarnato, Loredana

    2016-05-01

    In this work an active barrier system consisting of a thin and transparent film based on polyethylene terephthalate (PET) was studied. Dynamic oxygen absorption measurements were performed at different values of relative humidity and temperature, pointing out that humidity is a key factor in activating the oxidation of the polymer sample. Moreover, the thermal and optical properties of the films were investigated and a good correlation was found between the crystallinity increase and the consequent transparency reduction occurring after the oxygen absorption.

  9. Kinetic Studies on Photodeposition of Polydiacetylene Thin Film from Solution: Preliminary Determination of the Rate Law

    NASA Technical Reports Server (NTRS)

    Paley, M. S.; Armstrong, S.; Witherow, W. K.; Frazier, D. O.

    1996-01-01

    Preliminary kinetic studies were undertaken on the photodeposition of thin films of a polydiacetylene derivative of 2-methyl-4-nitroaniline from monomer solutions onto quartz substrates. Solutions of the monomer, DAMNA, in 1,2-dichloroethane at various concentrations were irradiated at 364 nm using an argon-ion laser at several intensities. It was found that the rate of polydiacetylene (PDAMNA) film photodeposition varies linearly with UV light intensity and as the square root of monomer concentration.

  10. Nanoindentation study of niobium nitride thin films on niobium fabricated by reactive pulsed laser deposition

    SciTech Connect

    Mamun, Md Abdullah Al; Farha, Ashraf Hassan; Ufuktepe, Yüksel; Elsayed-Ali, Hani E.; Elmustafa, Abdelmageed A.

    2015-03-01

    Nanomechanical and structural properties of NbNx films deposited on single crystal Nb using pulsed laser deposition for different substrate temperature were previously investigated as a function of film/substrate crystal structure (Mamun et al. (2012) [30]). In this study we focus on the effect of laser fluences and background nitrogen pressure on the nanomechanical and structural properties of NbNx films. The crystal structure and surface morphology of the thin films were tested by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. Using nanoindentation, the investigation of the nanomechanical properties revealed that the hardness of the NbNx films was directly influenced by the laser fluence for low background nitrogen pressure, whereas the nanomechanical hardness showed no apparent correlation with laser fluence at high background nitrogen pressure. The NbNx film hardness measured at 30% film thickness increased from 14.0 ± 1.3 to 18.9 ± 2.4 GPa when the laser fluence was increased from 15 to 25 J/cm2 at 10.7 Pa N2 pressure. X-ray diffraction showed NbNx films with peaks that correspond to δ-NbN cubic and β-Nb2N hexagonal phases in addition to the δ'-NbN hexagonal phase. Finally, increasing the laser fluence resulted in NbNx films with larger grain sizes.

  11. Effect of Polymer Confinement on the Film Drainage Behavior- An RICM Study

    NASA Astrophysics Data System (ADS)

    Borkar, Suraj; Ramchandran, Arun

    2015-11-01

    We consider the dynamic effects of confinement of macromolecular liquids on the film drainage process between a drop and a flat surface. Under confinement of the order of few molecular length scales, layering and adsorption of long chains of polymers can cause entropic repulsion due to a reduced configurational freedom. This repulsive force can prevent film rupture and lead to the formation of an equilibrium film. In the current work, experiments were conducted with deformable droplets settling under gravity in a suspending liquid for Bond numbers of O(10-4) . The film drainage was studied using a microinterferometric technique namely, Reflection Interference Contrast Microscopy (RICM) for two different systems: a) silicone oil drops in paraffin oil, b) glycerol drops in silicone oil. The RICM analysis for obtaining the film drainage profiles, was done using a combination of simple cosine theory and ray tracing algorithm. For the silicone oil-paraffin oil system, the film drainage behavior observed was as expected from simulations based on thin film drainage equations. On the other hand, glycerol drops of radii smaller than 130 μm, resulted in the formation of an equilibrium film of silicone oil with an approximate thickness of 10 nm. The origin of this repulsive force is attributed to the presence of an immobilized layer of adsorbed polymer chains. Film drainage observed in glycerol drops of radii larger than 130 μm, was found to destabilize in a non-axisymmetric mode. The rapid growth of this asymmetric instability can lead to stresses (O(100 Pa)) higher than the yield stress of the adsorbed polymer layer.

  12. Silicon Carbide Epitaxial Films Studied by Atomic Force Microscopy

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Silicon carbide (SiC) holds great potential as an electronic material because of its wide band gap energy, high breakdown electric field, thermal stability, and resistance to radiation damage. Possible aerospace applications of high-temperature, high-power, or high-radiation SiC electronic devices include sensors, control electronics, and power electronics that can operate at temperatures up to 600 C and beyond. Commercially available SiC devices now include blue light-emitting diodes (LED's) and high-voltage diodes for operation up to 350 C, with other devices under development. At present, morphological defects in epitaxially grown SiC films limit their use in device applications. Research geared toward reducing the number of structural inhomogeneities can benefit from an understanding of the type and nature of problems that cause defects. The Atomic Force Microscope (AFM) has proven to be a useful tool in characterizing defects present on the surface of SiC epitaxial films. The in-house High-Temperature Integrated Electronics and Sensors (HTIES) Program at the NASA Lewis Research Center not only extended the dopant concentration range achievable in epitaxial SiC films, but it reduced the concentration of some types of defects. Advanced structural characterization using the AFM was warranted to identify the type and structure of the remaining film defects and morphological inhomogeneities. The AFM can give quantitative information on surface topography down to molecular scales. Acquired, in part, in support of the Advanced High Temperature Engine Materials Technology Program (HITEMP), the AFM had been used previously to detect partial fiber debonding in composite material cross sections. Atomic force microscopy examination of epitaxial SiC film surfaces revealed molecular-scale details of some unwanted surface features. Growth pits propagating from defects in the substrate, and hillocks due, presumably, to existing screw dislocations in the substrates, were

  13. Study of topological spin texture in B20 crystalline FeGe films

    NASA Astrophysics Data System (ADS)

    Turgut, Emrah; Park, Albert; Nguyen, Kayla; Hovden, Robert; Kourkoutis, Lena; Muller, David; Fuchs, Gregory

    The possibility of efficient and robust information storage in B20-hellimagnet systems has been attracted significant interest. Although there have been promising transmission electron microscopy (TEM) and transport studies on bulk B20 crystalline materials, the development of applications motivates study of thin-film samples grown with scalable techniques such as magnetron sputtering. Here we report transport and characterization measurements of FeGe thin films grown on Si <111>by magnetron co-sputtering. We obtain well-oriented but polycrystalline FeGe films with the B20 crystalline phase after post-growth annealing. Low temperature TEM imaging reveals that the lattice mismatch between the Si substrate and FeGe film introduces disordered helical magnetic phases. In addition, bulk susceptibility measurements of a continuous film and AMR measurements of micron-size wires indicate helical, conical, and ferromagnetic phases, but not an obvious skyrmion phase. Similar to recent reports, our measurements confirm that the observations of additional contributions to Hall effect measurements in B20 materials are not necessarily proof of magnetic skyrmion phase, and that more careful experimental studies are needed to understand thin film properties of B20 materials.

  14. Analytical study of pressure balancing in gas film seals

    NASA Technical Reports Server (NTRS)

    Zuk, J.

    1973-01-01

    The load factor is investigated for subsonic and choked flow conditions, laminar and turbulent flows, and various seal entrance conditions. Both parallel sealing surfaces and surfaces with small linear deformation were investigated. The load factor for subsonic flow depends strongly on pressure ratio; under choked flow conditions, however the load factor is found to depend more strongly on film thickness and flow entrance conditions rather than pressure ratio. The importance of generating hydrodynamic forces to keep the seal balanced under severe and multipoint operation is also discussed.

  15. Photoconductivity study of acid on Zinc phthalocyanine pyridine thin films

    NASA Astrophysics Data System (ADS)

    Singh, Sukhwinder; Saini, G. S. S.; Tripathi, S. K.

    2016-05-01

    The Metal Phthalocyanine (MPc) have attracted much interest because of chemical and high thermal stability. Molecules forming a crystal of MPc are held together by weak attractive Vander Waals forces. Organic semiconductors have π conjugate bonds which allow electrons to move via π-electron cloud overlaps. Conduction mechanisms for organic semiconductor are mainly through tunneling; hopping between localized states, mobility gaps, and phonon assisted hopping. The photo conductivity of thin films of these complexes changes when exposed to oxidizing and reducing gases. Arrhenius plot is used to find the thermal activation energy in the intrinsic region and impurity scattering region. Arrhenius plotsare used to find the thermal activation energy.

  16. Computer simulation study of waterborne two-component polyurethane film formation

    NASA Astrophysics Data System (ADS)

    Yang, Shihai

    2007-12-01

    In this thesis, a coarse-grained computer simulation model is presented to study the film growth and macroscopic morphological feature (film thickness, surface roughness and longitudinal constituent density profile) in a multi-component polymer system. The mixture consists of reactive hydrophobic (H) and polar groups (P) in a reactive aqueous solvent ( A) which is also allowed to evaporate. Characteristics of each component such as hydrophobic and polar interactions, molecular weights, and specific functionality for the covalent bonding are used to describe the waterborne two-component polyurethane (WB 2K-PUR) film growth as an example. Systematic approach is employed to study the film growth step by step starting from the mixture of its basic ingradients. Attempts are made to capture such realistic features as perceived reaction kinetics and polymerization mechanism in the model. Constituents move stochastically via the Metropolis algorithm to explore thermo-dynamic equilibration while the kinetic reactions are incorporated through flexible covalent bonding (Bond Fluctuation Model) which may arrest the growth before reaching equilibrium. Film thickness grows and its interface evolves and equilibrates as the simulation continues. Power-law dependence is found for the initial growth of film thickness (h) and surface roughness (W) with time (t), i.e., h ∝ tgamma, W ∝ tbeta, with all simulations. In addition to the study of film evolution and surface morphlogy, constituent density profiles along the longitudinal direction are also investigated to develop a deep understanding of film infra-structure as well as to track the post-reaction product distribution. Effects of parameters such as temperature, relative humidity (initial water concentration), stoichiometry (NCO:OH ratio) and reaction rate are examined specifically in these simulations. Qualitative agreements with laboratory observations are found with our simulation results.

  17. Molecular orientation in soft matter thin films studied by resonant soft X-ray reflectivity

    SciTech Connect

    Mezger, Markus; Jerome, Blandine; Kortright, Jeffrey B.; Valvidares, Manuel; Gullikson, Eric; Giglia, Angelo; Mahne, Nicola; Nannarone, Stefano

    2011-01-12

    We present a technique to study depth profiles of molecular orientation in soft matter thin films with nanometer resolution. The method is based on dichroism in resonant soft X-ray reflectivity using linear s- and p-polarization. It combines the chemical sensitivity of Near-Edge X-ray Absorption Fine Structure spectroscopy to specific molecular bonds and their orientation relative to the polarization of the incident beam with the precise depth profiling capability of X-ray reflectivity. We demonstrate these capabilities on side chain liquid crystalline polymer thin films with soft X-ray reflectivity data at the carbon K edge. Optical constants of the anisotropic refractive index ellipsoid were obtained from a quantitative analysis using the Berreman formalism. For films up to 50 nm thickness we find that the degree of orientation of the long axis exhibits no depth variation and isindependent of the film thickness.

  18. Parametric study on the fuel film breakup of a cold start PFI engine

    NASA Astrophysics Data System (ADS)

    Wang, Y.-P.; Wilkinson, G. B.; Drallmeier, J. A.

    In order to provide more insight on improving the cold start fuel atomization for reducing unburned hydrocarbon emissions, the liquid fuel film breakup phenomenon in the intake valve/port region was investigated in depth for port-fuel-injected engines. Experiments were conducted using high-speed high-resolution imaging techniques to visualize the liquid film atomization and airflow patterns in an axisymmetric steady flow apparatus. The impact of valve/port seat geometry, surface roughness, and fuel properties on airflow separation and fuel film breakup were determined through a parametric study. CFD simulations were also performed with FLUENT to help understand the airflow behavior inside the intake port and valve gap region and its potential impact on fuel film atomization.

  19. Thin Films of a Main Chain Columnar Liquid Crystal: Studies of Structure, Phase Transitions and Alignment

    SciTech Connect

    Defaux, M.; DiMasi, E.; Vidal, Loic; Moller, Martin; Gearba, Raluca; Ivanov, Dimitri

    2009-03-22

    The structure of thin films of poly(di-n-propylsiloxane), PDPS, was studied with a combination of optical and atomic force microscopy, electron diffraction, and grazing incidence X-ray diffraction. Two different morphological features are observed in the mesomorphic films. The lamellar ribbons are composed of the chains oriented parallel to the plane of the substrate in which the reciprocal space 10 vector is vertical. The other feature with a circular symmetry, the cylindrite, contains the chains parallel to the substrate normal. The cylindrites and needles are essentially the same mesomorphic lamellae that develop differently under the conditions of confinement. The crystallization of PDPS films does not change the gross morphological features developed during the mesophase formation and mainly proceeds via epitaxial growth of the {alpha}-crystal on the parent mesophase. Spontaneous alignment of the mesomorphic PDPS films on the PTFE-rubbed substrates allows fabricating highly crystalline inorganic polymer surfaces oriented on the scale of centimeters.

  20. Growth temperature effect on a-Si:H thin films studied by constant photocurrent method

    NASA Astrophysics Data System (ADS)

    Wadibhasme, N. A.; Dusane, R. O.

    2013-02-01

    Hydrogenated amorphous silicon (a-Si:H) thin films are synthesized by tuning different process parameters among which substrate temperature of film growth plays an important role in monitoring the device quality of the film. In this paper we have used the constant photocurrent method (CPM) to study the effect of growth temperature on the electronic and optical parameters of a-Si:H films at different photon energies. This technique primarily measures the absorption coefficient which is a result of different electronic transitions that contribute to the photocurrent. The nature of absorption coefficient changes with growth temperature that explicitly provides the information about the density of defect states present in the mid gap of a-Si:H.

  1. Ultrafast lattice response of photoexcited thin films studied by X-ray diffraction

    PubMed Central

    Herzog, Marc; Bojahr, André; Leitenberger, Wolfram; Hertwig, Andreas; Bargheer, Matias

    2014-01-01

    Using ultrafast X-ray diffraction, we study the coherent picosecond lattice dynamics of photoexcited thin films in the two limiting cases, where the photoinduced stress profile decays on a length scale larger and smaller than the film thickness. We solve a unifying analytical model of the strain propagation for acoustic impedance-matched opaque films on a semi-infinite transparent substrate, showing that the lattice dynamics essentially depend on two parameters: One for the spatial profile and one for the amplitude of the strain. We illustrate the results by comparison with high-quality ultrafast X-ray diffraction data of SrRuO3 films on SrTiO3 substrates. PMID:26798784

  2. Deposition studies and coordinated characterization of MOCVD YBCO films on IBAD-MgO templates.

    SciTech Connect

    Aytug, Tolga; Paranthaman, Mariappan Parans; Heatherly Jr, Lee; Zhang, Yifei; Kim, Kyunghoon; Goyal, Amit; Maroni, V. A.; List III, Frederick Alyious

    2009-01-01

    A recently installed research metal organic chemical vapor deposition (MOCVD) system at Oak Ridge National Laboratory, provided by SuperPower, Inc., has been used to investigate the processing variables of MOCVD YBCO precursors and trends in the resulting properties. Systematic studies of film growth were carried out by optimizing deposition temperature and oxygen flow rate. Structural and superconducting properties of the YBCO films were analyzed by extensive X-ray diffraction, scanning electron microspcopy and transport measurements. The identification of intermediate phase formations after the YBCO precursor transformation was investigated with coordinated reel-to-reel Raman microprobe analysis. With the combination of these characterization techniques, an improved understanding of the growth characteristics of MOCVD YBCO films was established. Finally, critical current densities greater than 2 MA/cm2 for film thicknesses of 0.8 m have been demonstrated.

  3. Optical studies on electron beam evaporated Lithium Triborate films

    NASA Astrophysics Data System (ADS)

    Mohandoss, R.; Dhanuskodi, S.; Sanjeeviraja, C.

    2012-10-01

    Lithium triborate (LB3) has numerous applications in scintillator for neutron detection, laser weapon and communication. LB3 films have been prepared by electron beam evaporation technique under a pressure of 1 × 10-5 mbar on glass substrate at 323 K for 4 min. The crystallographic orientations and the lattice parameters (a = 8.55 (2); b = 5.09 (2); c = 7.39 (2) Å) were determined by powder XRD indicating the (1 1 1) preferential orientation of the film. The lower cut off wavelength at 325 nm with 75% transparency was measured from the UV-vis spectrum. The optical constants extinction coefficient (K), reflectance (R), the linear refractive index (1.34) and the optical energy band gap (˜4.0 eV) were estimated. The photoluminescence spectrum shows the emission peak in the visible region with low concentration of oxygen defects. LB3 is found to be second harmonic generation (SHG) active using a Q-switched Nd:YAG laser (1064 nm, 9 ns, 10 Hz). The nonlinear refractive index (n2 ˜ 10-16 cm2/W) and nonlinear absorption coefficient (β ˜ 10-2 cm/W) reveal (Z-scan technique) that the material has negative nonlinearity and self-focusing nature.

  4. Optical studies on electron beam evaporated lithium triborate films.

    PubMed

    Mohandoss, R; Dhanuskodi, S; Sanjeeviraja, C

    2012-10-01

    Lithium triborate (LB3) has numerous applications in scintillator for neutron detection, laser weapon and communication. LB3 films have been prepared by electron beam evaporation technique under a pressure of 1×10(-5) mbar on glass substrate at 323 K for 4 min. The crystallographic orientations and the lattice parameters (a=8.55 (2); b=5.09 (2); c=7.39 (2)Å) were determined by powder XRD indicating the (111) preferential orientation of the film. The lower cut off wavelength at 325 nm with 75% transparency was measured from the UV-vis spectrum. The optical constants extinction coefficient (K), reflectance (R), the linear refractive index (1.34) and the optical energy band gap (~4.0 eV) were estimated. The photoluminescence spectrum shows the emission peak in the visible region with low concentration of oxygen defects. LB3 is found to be second harmonic generation (SHG) active using a Q-switched Nd:YAG laser (1064 nm, 9 ns, 10 Hz). The nonlinear refractive index (n(2)~10(-16) cm(2)/W) and nonlinear absorption coefficient (β~10(-2) cm/W) reveal (Z-scan technique) that the material has negative nonlinearity and self-focusing nature. PMID:22925906

  5. Computer simulation studies of confined liquid-crystal films

    NASA Astrophysics Data System (ADS)

    Wall, Greg D.; Cleaver, Douglas J.

    1997-10-01

    In this paper we present results from molecular dynamics simulations performed using a system of Gay-Berne particles confined between two substrates in a slab geometry. We use a nonseparable anisotropic molecule-substrate interaction potential and investigate weak and moderate molecule-substrate coupling strengths. We find that for both coupling strengths a well-defined, tilted molecular layer forms at each wall and that the pretilt angle and layer density are only weakly dependent on temperature as the central region is cooled through isotropiclike and nematiclike regions. The orientationally ordered fluid formed at the center of the film is tilted in sympathy with the surface layers. At low temperatures, however, where the central region adopts a layered arrangement, a sharp change is observed in the pretilt angle. This transition is more marked in the weak-coupling system where the high-temperature tilted surface layers adopt an approximately planar arrangement at low temperatures and the system resembles a bookshelf-geometry smectic film. In the moderate-coupling system, the surface layers maintain some tilt in the presence of the layered central region, leading to a smectic-stripe phase arrangement.

  6. Surface study of films formed on copper and brass at open circuit potential

    NASA Astrophysics Data System (ADS)

    Procaccini, R.; Schreiner, W. H.; Vázquez, M.; Ceré, S.

    2013-03-01

    The corrosion resistance of Cu-Zn alloys strongly depends on the quality of the protective passive film. This study focuses on the influence of Zn on the composition of oxide films on copper and brass (Cu77Zn21Al2) in borax 0.1 mol L-1 (pH 9.2) solution, where the solubility of copper oxides is minimal. The effect of the presence of chloride ions at low concentration (0.01 mol L-1) in the electrolyte was also evaluated. Both conditions were studied using a set of different electrochemical, optical and surface techniques such as cyclic voltammetry, differential reflectance, X-ray photoelectron spectroscopy and Raman spectroscopy. A duplex Cu2O/CuO layer forms on copper at potentials positive to the open circuit potential (OCP), while in the case of brass, zinc compounds are also incorporated to the surface film. It also became evident that a surface film can be formed on these materials even at potentials negative to the OCP. Zn(II) species are the main constituents of the films growing on brass, while copper oxides are incorporated to the surface film when approaching the OCP. The presence of chloride ions at low concentrations contributes to the dissolution of the oxo-hydroxides formed during the early stages of the aging process at open circuit potential. Also, copper chloro-compounds are formed, as shown by Raman spectroscopy for both copper and brass electrodes.

  7. Keratin film made of human hair as a nail plate model for studying drug permeation.

    PubMed

    Lusiana; Reichl, Stephan; Müller-Goymann, Christel C

    2011-08-01

    The limited source of human nail plate for studying drug permeation inspired us to develop a nail plate model made of human hair keratin. The manufacturing process consisted of keratin extraction, dialysis, molding, solvent evaporation, and curing, producing a water-resistant film. The permeability of the film was examined using three markers: sodium fluorescein, rhodamine B, and fluorescein isothiocyanate-dextran as water-soluble, lipid-soluble, and large molecule models, respectively. Bovine hoof was used for comparison. First investigation showed that keratin films (thickness 120 μm) resembled hooves (thickness 100 μm) except that these films were more permeable to rhodamine B compared with hooves (1.8-fold, p<0.01). Subsequent investigations using ungual penetration enhancers (urea, thioglycolic acid, and papain) showed that keratin films were generally more susceptible than hooves. This study revealed that the produced keratin film offers a possibility as a human nail plate substitute. However, inclusion of the penetration enhancer must be carefully interpreted. PMID:21791369

  8. Studies of ferroelectric heterostructure thin films and interfaces via in situ analytical techniques.

    SciTech Connect

    Auciello, O.; Dhote, A.; Gao, Y.; Gruen, D. M.; Im, J.; Irene, E. A.; Krauss, A. R.; Mueller, A. H.; Ramesh, R.

    1999-08-30

    The science and technology of ferroelectric thin films has experienced an explosive development during the last ten years. Low-density non-volatile ferroelectric random access memories (NVFRAMs) are now incorporated in commercial products such as ''smart cards'', while high permittivity capacitors are incorporated in cellular phones. However, substantial work is still needed to develop materials integration strategies for high-density memories. We have demonstrated that the implementation of complementary in situ characterization techniques is critical to understand film growth and interface processes, which play critical roles in film microstructure and properties. We are using uniquely integrated time of flight ion scattering and recoil spectroscopy (TOF-ISARS) and spectroscopic ellipsometry (SE) techniques to perform in situ, real-time studies of film growth processes in the high background gas pressure required to growth ferroelectric thin films. TOF-ISARS provides information on surface processes, while SE permits the investigation of buried interfaces as they are being formed. Recent studies on SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub x}Sr{sub 1{minus}x}TiO{sub 3} (BST) film growth and interface processes are discussed.

  9. Structural and optical studies on antimony and zinc doped CuInS2 thin films

    NASA Astrophysics Data System (ADS)

    Ben Rabeh, M.; Chaglabou, N.; Kanzari, M.; Rezig, B.

    2009-11-01

    The influence of Zn and Sb impurities on the structural, optical and electrical properties of CuInS2 thin films on corning 7059 glass substrates was studied. Undoped and Zn or Sb doped CuInS2 thin films were deposited by thermal evaporation method and annealed in vacuum at temperature of 450 ∘C Undoped thin films were grown from CuInS2 powder using resistively heated tungsten boats. Zn species was evaporated from a thermal evaporator all together to the CuInS2 powder and Sb species was mixed in the starting powders. The amount of the Zn or Sb source was determined to be in the range 0-4 wt% molecular weight compared with the CuInS2 alloy source. The films were studied by means of X-ray diffraction (XRD), Optical reflection and transmission and resistance measurements. The films thicknesses were in the range 450-750 nm. All the Zn: CuInS2 and Sb: CuInS2 thin films have relatively high absorption coefficient between 104 cm-1 and 105 cm-1 in the visible and the near-IR spectral range. The bandgap energies are in the range of 1.472-1.589 eV for Zn: CuInS2 samples and 1.396-1.510 eV for the Sb: CuInS2 ones. The type of conductivity of these films was determined by the hot probe method. Furthermore, we found that Zn and Sb-doped CuInS2 thin films exhibit P type conductivity and we predict these species can be considered as suitable candidates for use as acceptor dopants to fabricate CuInS2-based solar cells.

  10. [Clinical and comparative study of the image quality of 3 digital radiographic systems, E-speed film and digitalized film

    PubMed

    Bóscolo, F N; de Oliveira, A E; de Almeida, S M; Haiter, C F; Haiter Neto, F

    2001-01-01

    The aim of this study was to evaluate, subjectively, the image quality of two CCD digital systems, a digital storage phosphor system, a digitized film and an E-speed film. Five objects were radiographed with 50, 60 and 70 kVp, with exposure times of 0.08, 0.13, 0.2, 0.4 and 0.8 s. In order to maximize the fidelity of the results, the dental X-ray unit employed was submitted to an evaluation so that the relation between exposure time and dose could be established. A good reproducibility was obtained. Six evaluators analyzed 375 images, using a scoring scale which ranged from 0 to 4. The results revealed different responses, indicating that the storage phosphor system had the best performance, in the various exposures employed. However, it was possible to conclude that all systems studied, except for the Sens-A-Ray, can offer images in ideal conditions for the diagnosis, as long as their latitudes are respected. PMID:11787321

  11. Dielectric and ellipsometric studies of the dynamics in thin films of isotactic poly(methylmethacrylate) with one free surface.

    PubMed

    Sharp, J S; Forrest, J A

    2003-03-01

    We have performed dielectric loss measurements at 1 kHz on thin films of isotactic poly(methyl methacrylate). A key distinction of our studies is that the samples measured were supported films with one free surface rather than films that have metallic electrodes covering both surfaces. This unique sample geometry allows us to eliminate any effects due to evaporation of metal onto the top film surface and provides a unique opportunity to make direct comparisons between dielectric loss and glass transition measurements. Film thicknesses in the range from 6 microm to 7 nm were prepared on Al coated substrates. The dielectric loss peak and ellipsometric glass transition temperature of all films were measured. The dielectric loss was found to exhibit no discernible film thickness dependence in either the temperature of the maximum loss value or the shape of the loss curve. In contrast, the measured T(g) values were found to decrease with decreasing film thickness with a maximum shift of 10 K for a 7-nm film. Dielectric measurements were also made on Al coated films and these samples also showed no shift in the temperature of the loss peak. Finally, the T(g) measurements were also made on Si substrates. These values exhibited an increasing T(g) value with film thickness with a maximum increase of approximately 15 K being measured for a 7-nm film. PMID:12689094

  12. A study of the chemical, mechanical, and surface properties of thin films of hydrogenated amorphous carbon

    SciTech Connect

    Vandentop, G.J.

    1990-07-01

    Amorphous hydrogenated carbon (a-C:H) films were studied with the objective of elucidating the nucleation and growth mechanisms, and the origin of their unique physical properties. The films were deposited onto Si(100) substrates both on the powered (negatively self-biased) and on the grounded electrodes from methane in an rf plasma (13.56 MHz) at 65 mTorr and 300 to 370 K. The films produced at the powered electrode exhibited superior mechanical properties, such as high hardness. A mass spectrometer was used to identify neutral species and positive ions incident on the electrodes from the plasma, and also to measure ion energies. The effect of varying ion energy flux on the properties of a-C:H films was investigated using a novel pulsed biasing technique. It was demonstrated that ions were not the dominant deposition species as the total ion flux measured was insufficient to account for the observed deposition rate. The interface between thin films of a-C:H and silicon substrates was investigated using angle resolved x-ray photoelectron spectroscopy. A silicon carbide layer was detected at the interface of a hard a-C:H film formed at the powered electrode. At the grounded electrode, where the kinetic energy is low, no interfacial carbide layer was observed. Scanning tunneling microscopy and high energy electron energy loss spectroscopy was used to investigate the initial stages of growth of a-C:H films. On graphite substrates, films formed at the powered electrode were observed to nucleate in clusters approximately 50 {Angstrom} in diameter, while at the grounded electrode no cluster formation was observed. 58 figs.

  13. A nanosecond pulsed laser heating system for studying liquid and supercooled liquid films in ultrahigh vacuum

    NASA Astrophysics Data System (ADS)

    Xu, Yuntao; Dibble, Collin J.; Petrik, Nikolay G.; Smith, R. Scott; Joly, Alan G.; Tonkyn, Russell G.; Kay, Bruce D.; Kimmel, Greg A.

    2016-04-01

    A pulsed laser heating system has been developed that enables investigations of the dynamics and kinetics of nanoscale liquid films and liquid/solid interfaces on the nanosecond time scale in ultrahigh vacuum (UHV). Details of the design, implementation, and characterization of a nanosecond pulsed laser system for transiently heating nanoscale films are described. Nanosecond pulses from a Nd:YAG laser are used to rapidly heat thin films of adsorbed water or other volatile materials on a clean, well-characterized Pt(111) crystal in UHV. Heating rates of ˜1010 K/s for temperature increases of ˜100-200 K are obtained. Subsequent rapid cooling (˜5 × 109 K/s) quenches the film, permitting in-situ, post-heating analysis using a variety of surface science techniques. Lateral variations in the laser pulse energy are ˜±2.7% leading to a temperature uncertainty of ˜±4.4 K for a temperature jump of 200 K. Initial experiments with the apparatus demonstrate that crystalline ice films initially held at 90 K can be rapidly transformed into liquid water films with T > 273 K. No discernable recrystallization occurs during the rapid cooling back to cryogenic temperatures. In contrast, amorphous solid water films heated below the melting point rapidly crystallize. The nanosecond pulsed laser heating system can prepare nanoscale liquid and supercooled liquid films that persist for nanoseconds per heat pulse in an UHV environment, enabling experimental studies of a wide range of phenomena in liquids and at liquid/solid interfaces.

  14. Synthesis and pseudocapacitive studies of composite films of polyaniline and manganese oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Liang; Sun, Li-Jie; Luan, Feng; Liang, Ying; Li, Yat; Liu, Xiao-Xia

    We report the synthesis and pseudocapacitive studies of a composite film (PANI-ND-MnO 2) of polyaniline (PANI) and manganese oxide (MnO 2) nanoparticles. To enhance the interaction of MnO 2 and PANI, the surfaces of MnO 2 nanoparticles were modified by a silane coupling reagent, triethoxysilylmethyl N-substituted aniline (ND42). The composite film was obtained via controlled electro-co-polymerization of aniline and N-substituted aniline grafted on surfaces of MnO 2 nanoparticles (ND-MnO 2) on a carbon cloth in a electrolyte of 0.5 M H 2SO 4 and 0.6 M (NaPO 3) 6. In comparison to similarly prepared PANI film, the incorporation of MnO 2 nanoparticles substantially increases the effective surface area of the film by reducing the size of rod-like PANI aggregates and avoiding the entanglement of these PANI nanorods. Significantly, we observed significant enhancement of specific capacitance in PANI-ND-MnO 2 film compared to PANI-MnO 2 film prepared in a similar condition, indicating that the presence of the coupling reagent can improve the electrochemical performance of PANI composite film. A symmetric model capacitor has been fabricated by using two PANI-ND-MnO 2 nanocomposite films as electrodes. The PANI-ND-MnO 2 capacitor showed an average specific capacitance of ∼80 F g -1 and a stable coulombic efficiency of ∼98% over 1000 cycles. The results demonstrated that PANI-ND-MnO 2 nanocomposites are promising materials for supercapacitor electrode and the importance of designing and manipulating the interaction between PANI and MnO 2 for fundamentally improving capacitive properties.

  15. A nanosecond pulsed laser heating system for studying liquid and supercooled liquid films in ultrahigh vacuum.

    PubMed

    Xu, Yuntao; Dibble, Collin J; Petrik, Nikolay G; Smith, R Scott; Joly, Alan G; Tonkyn, Russell G; Kay, Bruce D; Kimmel, Greg A

    2016-04-28

    A pulsed laser heating system has been developed that enables investigations of the dynamics and kinetics of nanoscale liquid films and liquid/solid interfaces on the nanosecond time scale in ultrahigh vacuum (UHV). Details of the design, implementation, and characterization of a nanosecond pulsed laser system for transiently heating nanoscale films are described. Nanosecond pulses from a Nd:YAG laser are used to rapidly heat thin films of adsorbed water or other volatile materials on a clean, well-characterized Pt(111) crystal in UHV. Heating rates of ∼10(10) K/s for temperature increases of ∼100-200 K are obtained. Subsequent rapid cooling (∼5 × 10(9) K/s) quenches the film, permitting in-situ, post-heating analysis using a variety of surface science techniques. Lateral variations in the laser pulse energy are ∼±2.7% leading to a temperature uncertainty of ∼±4.4 K for a temperature jump of 200 K. Initial experiments with the apparatus demonstrate that crystalline ice films initially held at 90 K can be rapidly transformed into liquid water films with T > 273 K. No discernable recrystallization occurs during the rapid cooling back to cryogenic temperatures. In contrast, amorphous solid water films heated below the melting point rapidly crystallize. The nanosecond pulsed laser heating system can prepare nanoscale liquid and supercooled liquid films that persist for nanoseconds per heat pulse in an UHV environment, enabling experimental studies of a wide range of phenomena in liquids and at liquid/solid interfaces. PMID:27131543

  16. Synthesis, characterization, and photoconductivity studies on nanocrystalline TiO2 films doped with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Valverde-Aguilar, G.; García-Macedo, J. A.; Galván-Ramírez, P.; Rentería-Tapia, V.

    2009-08-01

    Nanocrystalline TiO2 films doped with gold nanoparticles were synthesized by the sol-gel process at room temperature. The TiO2 films were synthesized by using tetrabutyl orthotitanate as the inorganic precursor. The films were spin-coated on glass wafers. The samples were annealed at 100°C for 30 minutes and sintered at 520°C for 1 hour to generated anatase and rutile phases. The films were characterized using UV-Vis absorption spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. An absorption peak located at around 651 nm is due to the surface plasmon resonance of the gold nanoparticles. Optical absorption spectrum was fitted by Gans model by using a high refractive index (nlocal = 2.6). This high index is related to the high content of anatase nanoparticles embedded in the film. Photoconductivity studies were performed on nanocrystalline (anatase phase) films. The experimental data were fitted with straight lines at darkness and under illumination at 515 nm and 645 nm. This indicates an ohmic behavior. Transport parameters were calculated. Results are discussed.

  17. Experimental and computational studies of film cooling with compound angle injection

    SciTech Connect

    Goldstein, R.J.; Eckert, E.R.G.; Patankar, S.V.; Simon, T.W.

    1995-12-31

    The thermal efficiency of gas turbine systems depends largely on the turbine inlet temperature. Recent decades have seen a steady rise in the inlet temperature and a resulting reduction in fuel consumption. At the same time, it has been necessary to employ intensive cooling of the hot components. Among various cooling methods, film cooling has become a standard method for cooling of the turbine airfoils and combustion chamber walls. The University of Minnesota program is a combined experimental and computational study of various film-cooling configurations. Whereas a large number of parameters influence film cooling processes, this research focuses on compound angle injection through a single row and through two rows of holes. Later work will investigate the values of contoured hole designs. An appreciation of the advantages of compound angle injection has risen recently with the demand for more effective cooling and with improved understanding of the flow; this project should continue to further this understanding. Approaches being applied include: (1) a new measurement system that extends the mass/heat transfer analogy to obtain both local film cooling and local mass (heat) transfer results in a single system, (2) direct measurement of three-dimensional turbulent transport in a highly-disturbed flow, (3) the use of compound angle and shaped holes to optimize film cooling performance, and (4) an exploration of anisotropy corrections to turbulence modeling of film cooling jets.

  18. Single-molecule studies of acidity distributions in mesoporous aluminosilicate thin films.

    PubMed

    Sun, Xiaojiao; Xie, Jingyi; Xu, Jiayi; Higgins, Daniel A; Hohn, Keith L

    2015-05-26

    Solid acid catalysts are important for many petrochemical processes. The ensemble methods most often employed to characterize acid site properties in catalyst materials provide limited insights into their heterogeneity. Single-molecule (SM) fluorescence spectroscopic methods provide a valuable route to probing the properties of individual microenvironments. In this work, dual-color SM methods are adopted to study acidity distributions in mesoporous aluminosilicate (Al-Si) films prepared by the sol-gel method. The highly fluorescent pH-sensitive dye C-SNARF-1 was employed as a probe. The ratio of C-SNARF-1 emission in two bands centered at 580 and 640 nm provides an effective means to sense the pH of bulk solutions. In mesoporous thin films, SM emission data provide a measure of the effective pH of the microenvironment in which each molecule resides. SM emission data were obtained from mesoporous Al-Si films as a function of Al2O3 content for films ranging from 0% to 30% alumina. Histograms of the emission ratio reveal a broad distribution of acidity properties, with the film microenvironments becoming more acidic, on average, as the alumina content of the films increases. This work provides new insights into the distribution of Brønsted acidity in solid acids that cannot be obtained by conventional means. PMID:25941900

  19. [Study of Surface Enhanced Raman Spectroscopy on Copper Films Modified by Ion Beam].

    PubMed

    Ding, Liang-liang; Hong, Rui-jin; Tao, Chun-xian; Zhang, Da-wei

    2015-11-01

    Surface-enhanced Raman Spectroscopy (SERS) was a rapid non-destructive testing. It was based on detecting molecule vibrational spectrum which was adsorbed on the metallic surface. Now it was widely used in surface adsorption, electrochemical catalysis, sensors, bio-medical testing, trace amount analysis and other fields. In our experiment, copper metallic films were deposited 50 nm on BK7 glass substrates by direct current magnetron sputtering. And then the films were employed for the Ar ion beam etching modification. The structure, morphology and optical properties was characterized by X-ray diffraction (XRD), Atomic Force Microscope (AFM), spectrophotometer and Raman spectroscopy. In the XRD graph, the peak value of modify copper film were the same with the untreated film. So the structure of copper film was not change. With increasing the power of Ar ion, the surface roughness was changed, and scattered spectrum intensity was increased by surface roughness added. With Rhodamine B (Rh B) as a probe molecule, Raman scattered spectrum was detected on modify copper film. Compared with the different samples, we can find the Raman signal was enhanced by surface roughness added. It will have some value on study the principles of SERS. PMID:26978913

  20. Experimental and computational studies of film cooling with compound angle injection

    SciTech Connect

    Goldstein, R.J.; Eckert, E.R.G.; Patankar, S.V.

    1995-10-01

    The thermal efficiency of gas turbine systems depends largely on the turbine inlet temperature. Recent decades have seen a steady rise in the inlet temperature and a resulting reduction in fuel consumption. At the same time, it has been necessary to employ intensive cooling of the hot components. Among various cooling methods, film cooling has become a standard method for cooling of the turbine airfoils and combustion chamber walls. The University of Minnesota program is a combined experimental and computational study of various film-cooling configurations. Whereas a large number of parameters influence film cooling processes, this research focuses on compound angle injection through a single row and through two rows of holes. Later work will investigate the values of contoured hole designs. An appreciation of the advantages of compound angle injection has risen recently with the demand for more effective cooling and with improved understanding of the flow; this project should continue to further this understanding. Approaches being applied include: (1) a new measurement system that extends the mass/heat transfer analogy to obtain both local film cooling and local mass (heat) transfer results in a single system, (2) direct measurement of three-dimensional turbulent transport in a highly-disturbed flow, (3) the use of compound angle and shaped holes to optimize film cooling performance, and (4) an exploration of anisotropy corrections to turbulence modeling of film cooling jets.

  1. Studies of polycrystalline pentacene thin-film transistors at the microscopic level

    NASA Astrophysics Data System (ADS)

    Cheng, Horng-Long; Chou, Wei-Yang; Kuo, Chia-Wei; Mai, Yu-Shen; Tang, Fu-Ching; Lai, Szu-Hao

    2006-08-01

    The electronic transport properties of polycrystalline pentacene-based thin film transistors (TFTs) were investigated at the microscopic level using microRaman spectroscopy. All the pentacene film, which were thermally evaporated as a layer with thickness of 70 nm, featured polycrystalline structure with only "thin film" phase polymorph and grain morphology as verified by x-ray diffraction (XRD) measurements. We have investigated the molecular vibrational modes of pentacene in the active channel during operations the organic TFT devices using in-situ Raman spectroscopy. Extra vibrational modes resulting from vibrational coupling effect in pentacene film were studied. The interlayer and intralayer intermolecular vibrational coupling energy was calculated from the Davydov splitting using a simple coupled-oscillator model. The results suggest that the C-H in-plane bending vibrational coupling energy of pentacene molecules in solid film is affected by operating device. Additionally, the aromatic C-C stretching vibrational modes also were investigated. However, it is rather difficult to obtain the variations of lattice parameters of pentacene film in a very small active channel by using electron diffraction and XRD. At the same time, MicroRaman technique provides the capability to explore the intermolecular coupling and molecular structure modifications.

  2. X-ray photoelectron spectroscopy study of thin TiO2 films cosputtered with Al

    NASA Astrophysics Data System (ADS)

    Hsu, Jin-Cherng; Wang, Paul W.; Lee, Cheng-Chung

    2006-06-01

    In this study, titanium dioxide (TiO2) films were fabricated by cosputtering of a titanium (Ti) target and an aluminum (Al) slice in a smaller area by an ion-beam sputtering deposition method. The sputtered films were postannealed at 450 °C. The x-ray photoelectron spectroscopy spectra were categorized by their oxygen bonding variations, which include high-binding-energy oxygen, (HBO), bridging oxygen, low-binding-energy oxygen, and shifts of the binding energies (BEs) of oxygen (O) and Ti signals. The enhancement of HBO and higher BE shifts of the O 1s spectra as a function of cosputtered Al in the film imply the formation of an Al—O—Ti linkage. Corresponding changes in the Ti 2p spectra further confirm the modification of properties of the cosputtered film that results from the variation of the chemical bonding environment. An observed correlation between the chemical structure and optical absorption of the Al cosputtered films can be used to modify the optical properties of the film.

  3. Optical, structural and electrochromic studies of molybdenum oxide thin films with nanorod structure

    NASA Astrophysics Data System (ADS)

    Dhanasankar, M.; Purushothaman, K. K.; Muralidharan, G.

    2010-02-01

    The MoO 3 thin films were prepared via sol-gel dip coating method on glass and FTO glass substrate. The optical and other properties of multilayered MoO 3 films with 2-10 layers were investigated. The MoO 3 films were studied using UV-Visible transmission, XRD, SEM, FTIR and Cyclic Voltammetry (CV) measurements. The band gap value for MoO 3 films was evaluated and in the range of 3.2 eV-3.72 eV. The XRD spectrum reveals that the crystallinity increases along the (020) and (040) planes with the increase in thickness. The SEM images showed the formation of nanorods upto six layers. The FTIR spectrum confirms the formation of MoO 3. The 6 layered films show the maximum anodic (spike)/cathodic (peak) diffusion coefficient of 18.84/1.701 × 10 -11 cm 2/s. The same film exhibits the change in optical transmission of 49% with the bleached/coloured state transmission of 62/13%.

  4. Study of narrowband single photon emitters in polycrystalline diamond films

    SciTech Connect

    Sandstrom, Russell G.; Shimoni, Olga; Martin, Aiden A.; Aharonovich, Igor

    2014-11-03

    Quantum information processing and integrated nanophotonics require robust generation of single photon emitters on demand. In this work, we demonstrate that diamond films grown on a silicon substrate by microwave plasma chemical vapor deposition can host bright, narrowband single photon emitters in the visible—near infra-red spectral range. The emitters possess fast lifetime (∼several ns), absolute photostability, and exhibit full polarization at excitation and emission. Pulsed and continuous laser excitations confirm their quantum behaviour at room temperature, while low temperature spectroscopy is performed to investigate inhomogeneous broadening. Our results advance the knowledge of solid state single photon sources and open pathways for their practical implementation in quantum communication and quantum information processing.

  5. Study of high [Tc] superconducting thin films grown by MOCVD

    SciTech Connect

    Erbil, A.

    1990-01-01

    Work is described briefly, which was carried out on development of techniques to grow metal-semiconductor superlattices (artificially layered materials) and on the copper oxide based susperconductors (naturally layered materials). The current growth technique utilized is metalorganic chemical vapor deposition (MOCVD). CdTe, PbTe, La, LaTe, and Bi[sub 2]Te[sub 3] were deposited, mostly on GaAs. Several YBa[sub 2]Cu[sub 3]O[sub 7] compounds were obtained with possible superconductivity at temperatures up to 550 K (1 part in 10[sup 4]). YBa[sub 2]Cu[sub 3]O[sub 7[minus]x] and Tl[sub 2]CaBa[sub 2]Cu[sub 2]O[sub y] thin films were deposited by MOCVD on common substrates such as glass.

  6. Experimental study of a gas film in a tube

    NASA Astrophysics Data System (ADS)

    Volchkov, E. P.; Lebedev, V. P.; Shishkin, N. E.

    1983-02-01

    An experimental investigation of the mixing of two coaxial flows in a cylindrical channel is described, and the efficiency of the thermal protection (e.e., film cooling) of the adiabatic wall is determined. Angles of twist of the secondary peripheral flow to the main flow were 0.58, and 74 deg. Measurements were made of temperature, the degree of flow turbulence, and the energy spectrum of axial velocity pulsations. It is shown that twist of the peripheral flow leads to a suppression of velocity pulsations in the near-axial zone and to an increase in the length of the potential-flow region. It is shown that generalized temperature profiles transverse to the channel in the presence and in the absence of twist coincide, and that the efficiency of a twisted screen varies along the channel more slowly than that of a nontwisted screen.

  7. Resistance to moist conditions of whey protein isolate and pea starch biodegradable films and low density polyethylene nondegradable films: a comparative study

    NASA Astrophysics Data System (ADS)

    Mehyar, G. F.; Bawab, A. Al

    2015-10-01

    Biodegradable packaging materials are degraded under the natural environmental conditions. Therefore using them could alleviate the problem of plastics accumulation in nature. For effective replacement of plastics, with biodegradable materials, biodegradable packages should keep their properties under the high relative humidity (RH) conditions. Therefore the objectives of the study were to develop biodegradable packaging material based on whey protein isolate (WPI) and pea starch (PS). To study their mechanical, oxygen barrier and solubility properties under different RHs compared with those of low density polyethylene (LDPE), the most used plastic in packaging. Films of WPI and PS were prepared separately and conditioned at different RH (30-90%) then their properties were studied. At low RHs (<50%), WPI films had 2-3 times lower elongation at break (E or stretchability) than PS and LDPE. Increasing RH to 90% significantly (P<0.01) increased the elongation of PS but not WPI and LDPE films. LDPE and WPI films kept significantly (P<0.01) higher tensile strength (TS) than PS films at high RH (90%). Oxygen permeability (OP) of all films was very low (<0.5 cm3 μm m-2 d-1 kPa-1) below 40% RH but increased for PS films and became significantly (P<0.01) different than that of LDPE and WPI at > 40% RH. Oxygen permeability of WPI and LDPE did not adversely affected by increasing RH to 65%. Furthermore, WPI and LDPE films had lower degree of hydration at 50% and 90% RH and total soluble matter than PS films. These results suggest that WPI could be successfully replacing LDPE in packaging of moist products.

  8. A Numerical Study of Anti-Vortex Film Cooling Designs at High Blowing Ratio

    NASA Technical Reports Server (NTRS)

    Heidmann, James D.

    2008-01-01

    A concept for mitigating the adverse effects of jet vorticity and liftoff at high blowing ratios for turbine film cooling flows has been developed and studied at NASA Glenn Research Center. This "anti-vortex" film cooling concept proposes the addition of two branched holes from each primary hole in order to produce a vorticity counter to the detrimental kidney vortices from the main jet. These vortices typically entrain hot freestream gas and are associated with jet separation from the turbine blade surface. The anti-vortex design is unique in that it requires only easily machinable round holes, unlike shaped film cooling holes and other advanced concepts. The anti-vortex film cooling hole concept has been modeled computationally for a single row of 30deg angled holes on a flat surface using the 3D Navier-Stokes solver Glenn-HT. A modification of the anti-vortex concept whereby the branched holes exit adjacent to the main hole has been studied computationally for blowing ratios of 1.0 and 2.0 and at density ratios of 1.0 and 2.0. This modified concept was selected because it has shown the most promise in recent experimental studies. The computational results show that the modified design improves the film cooling effectiveness relative to the round hole baseline and previous anti-vortex cases, in confirmation of the experimental studies.

  9. Surface-sensitive UHV dielectric studies of nanoscale organic thin films: Adsorption, crystallization, and sublimation

    NASA Astrophysics Data System (ADS)

    Underwood, Jason M.

    Nanoscale systems are small collections of atoms or molecules, which as a result of their limited extent, show measurable thermodynamic deviations from bulk samples of the same species. The deviations may result from purely finite-size effects, or may be due to an increased significance of the interaction between the nanoscale system and its container. Ultra-thin (<100 nm) films of organic molecules adsorbed on surfaces afford unique opportunities to study the interplay of forces relevant to nanoscale physics. This thesis describes the development of a novel ultra-high vacuum apparatus to study the behavior of adsorbed polar molecules via dielectric spectroscopy (UHV-DS). Ultra-thin films are grown and characterized in-situ. The use of interdigitated electrode capacitors and a ratio-transformer bridge technique yields resolutions of ˜1 aF and ˜10-5 ppm in the capacitance and loss tangent, respectively. Typical sensitivity is 10 aF per monolayer at 80 K. Results are given for studies on water, methanol, and Cp* (a synthetic molecular rotor). The desorption event in the dielectric spectra is correlated with thermal desorption spectroscopy. During growth of methanol films, we observe partial crystallization for temperatures above ≳ 100 K. Crystallization is also observed upon heating glassy films grown at 80 K. Finally, we discuss UHV-DS as a probe for solid thin-film vapor pressure measurements, and show that our data on methanol compare favorably with those in the literature.

  10. Structural and optical studies of 100 MeV Au irradiated thin films of tin oxide

    NASA Astrophysics Data System (ADS)

    Jaiswal, Manoj Kumar; Kanjilal, D.; Kumar, Rajesh

    2013-11-01

    Thin films of tin(IV) oxide (SnO2) of 100 nm thickness were grown on silicon (1 0 0) matrices by electron beam evaporation deposition technique under high vacuum. The thicknesses of these films were monitored by piezo-sensor attached to the deposition chamber. Nanocrystallinity is achieved in these thin films by 100 MeV Au8+ using 1 pnA current at normal incidence with ion fluences varying from 1 × 1011 ions/cm2 to 5 × 1013 ions/cm2. Swift Heavy Ion beam irradiation was carried out by using 15 UD Pelletron Accelerator at IUAC, New Delhi, India. Optical studies of pristine and ion irradiated thin films were characterized by UV-Visible spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy. Prominent peak at 610 cm-1 in FTIR spectrum confirmed the O-Sn-O bonding of tin(IV) oxide. For Surface topographical studies and grain size calculations, these films were characterized by Atomic Force Microscope (AFM) using Nanoscope III-A. Crystallinity and phase transformation due to irradiation of pristine and irradiated films were characterized by Glancing Angle X-ray Diffraction (GAXRD) using Brucker-D8 advance model. GAXRD results show improvement in crystallinity and phase transformation due to swift heavy ion irradiation. Grain size distribution was verified by AFM and GAXRD results. Swift heavy ion induced modifications in thin films of SnO2 were confirmed by the presence of prominent peaks at 2θ values of 30.65°, 32.045°, 43.94°, 44.96° and 52.36° in GAXRD spectrum.

  11. Study on Stretching Methods of Biaxially Stretched Co-polyester Film with Has Uniaxially Heat Shrinkage Properties

    NASA Astrophysics Data System (ADS)

    Haruta, Masayuki; Mukouyama, Yukinobu; Tabota, Norimi; Ito, Katsuya; Nonomura, Chisato

    Heat shrinkable film made of stretched film is widely used for decorative labels by attaching on PET bottles with heat shrinkage by steam or dry heating. Trouble cancellation in the installation process of the PET bottle is necessary. The purpose of this study is development of uniaxially heat shrinkable co-polyester film that has strength both in the machine direction (MD) and transverse direction (TD). The film production was performed using sequential biaxial stretched process that combined roll stretching with TD stretching. Cast film was processed in the order of TD stretching-Anneal 1-MD stretching-Anneal 2. As a result, the heat shrinkable film that shrunk only in MD got high tensile strength both in MD and TD. The anneal 1 temperature over Tg (Glass transition temperature) of material resin was needed to obtain the heat shrinkable film shrunk in MD after TD stretching.

  12. Structural and morphological studies on Bi1-xCaxMnO3 thin films grown by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Pugazhvadivu, K. S.; Santhiya, M.; Balakrishnan, L.; Tamilarasan, K.

    2016-05-01

    Bi1-xCaxMnO3 (0 ≤ X ≤ 0.4) thin films are deposited on n-type Si (100) substrate at 800 °C by RF magnetron sputtering. X-ray diffraction pattern shows that the films are crystallized in monoclinic structure with C2 space group. The crystallite size and induced strain in the prepared films are measured by W-H plot. The cell parameters and texture coefficient of the films are calculated. The surface morphology of the films is examined by atomic force microscope. The study confirms the optimum level of calcium doping is 20 at. % in Bi site of BiMnO3 film, these findings pave the way for further research in the Ca modified BiMnO3 films towards device fabrication.

  13. Stress and efficiency studies in edge-defined film-fed growth

    NASA Technical Reports Server (NTRS)

    Kalejs, J.

    1986-01-01

    The progress was reviewed for stress and efficiency studies of edge-defined film-fed growth (EFG) material. Effort was concentrated on the definition of condiitions that will reduce stress, on quantifying dislocation electrical activity and limits on solar cell efficiency, and on studying the effects of dopants on EFG characteristics.

  14. In-situ x-ray absorption study of copper films in ground watersolutions

    SciTech Connect

    Kvashnina, K.O.; Butorin, S.M.; Modin, A.; Soroka, I.; Marcellini, M.; Nordgren, J.; Guo, J.-H.; Werme, L.

    2007-10-29

    This study illustrates how the damage from copper corrosion can be reduced by modifying the chemistry of the copper surface environment. The surface modification of oxidized copper films induced by chemical reaction with Cl{sup -} and HCO{sub 3}{sup -} in aqueous solutions was monitored by in situ X-ray absorption spectroscopy. The results show that corrosion of copper can be significantly reduced by adding even a small amount of sodium bicarbonate. The studied copper films corroded quickly in chloride solutions, whereas the same solution containing 1.1 mM HCO{sub 3}{sup -} prevented or slowed down the corrosion processes.

  15. In situ X-ray absorption study of copper films in ground water solutions

    NASA Astrophysics Data System (ADS)

    Kvashnina, K. O.; Butorin, S. M.; Modin, A.; Soroka, I.; Marcellini, M.; Nordgren, J.; Guo, J.-H.; Werme, L.

    2007-10-01

    This study illustrates how the damage from copper corrosion can be reduced by modifying the chemistry of the copper surface environment. The surface modification of oxidized copper films induced by chemical reaction with Cl - and HCO3- in aqueous solutions was monitored by in situ X-ray absorption spectroscopy. The results show that corrosion of copper can be significantly reduced by adding even a small amount of sodium bicarbonate. The studied copper films corroded quickly in chloride solutions, whereas the same solution containing 1.1 mM HCO3- prevented or slowed down the corrosion processes.

  16. A study on the evolution of dielectric function of ZnO thin films with decreasing film thickness

    SciTech Connect

    Li, X. D.; Chen, T. P. Liu, P.; Liu, Y.; Liu, Z.; Leong, K. C.

    2014-03-14

    Dielectric function, band gap, and exciton binding energies of ultrathin ZnO films as a function of film thickness have been obtained with spectroscopic ellipsometry. As the film thickness decreases, both real (ε{sub 1}) and imaginary (ε{sub 2}) parts of the dielectric function decrease significantly, and ε{sub 2} shows a blue shift. The film thickness dependence of the dielectric function is shown related to the changes in the interband absorption, discrete-exciton absorption, and continuum-exciton absorption, which can be attributed to the quantum confinement effect on both the band gap and exciton binding energies.

  17. Simulation study of twisted crystal growth in organic thin films

    NASA Astrophysics Data System (ADS)

    Fang, Alta; Haataja, Mikko

    2015-10-01

    Many polymer and organic small-molecule thin films crystallize with microstructures that twist or curve in a regular manner as crystal growth proceeds. Here we present a phase-field model that energetically favors twisting of the three-dimensional crystalline orientation about and along particular axes, allowing morphologies such as banded spherulites, curved dendrites, and "s"- or "c"-shaped needle crystals to be simulated. When twisting about the fast-growing crystalline axis is energetically favored and spherulitic growth conditions are imposed, crystallization occurs in the form of banded spherulites composed of radially oriented twisted crystalline fibers. Due to the lack of symmetry, twisting along the normal growth direction leads to heterochiral banded spherulites with opposite twist handedness in each half of the spherulite. When twisting is instead favored about the axis perpendicular to the plane of the substrate and along the normal growth direction under diffusion-limited single-crystalline growth conditions, crystallization occurs in the form of curved dendrites with uniformly rotating branches. We show that the rate at which the branches curve affects not only the morphology but also the overall kinetics of crystallization, as the total crystallized area at a given time is maximized for a finite turning rate.

  18. Simulation study of twisted crystal growth in organic thin films.

    PubMed

    Fang, Alta; Haataja, Mikko

    2015-10-01

    Many polymer and organic small-molecule thin films crystallize with microstructures that twist or curve in a regular manner as crystal growth proceeds. Here we present a phase-field model that energetically favors twisting of the three-dimensional crystalline orientation about and along particular axes, allowing morphologies such as banded spherulites, curved dendrites, and "s"- or "c"-shaped needle crystals to be simulated. When twisting about the fast-growing crystalline axis is energetically favored and spherulitic growth conditions are imposed, crystallization occurs in the form of banded spherulites composed of radially oriented twisted crystalline fibers. Due to the lack of symmetry, twisting along the normal growth direction leads to heterochiral banded spherulites with opposite twist handedness in each half of the spherulite. When twisting is instead favored about the axis perpendicular to the plane of the substrate and along the normal growth direction under diffusion-limited single-crystalline growth conditions, crystallization occurs in the form of curved dendrites with uniformly rotating branches. We show that the rate at which the branches curve affects not only the morphology but also the overall kinetics of crystallization, as the total crystallized area at a given time is maximized for a finite turning rate. PMID:26565254

  19. A Microbeam Bending Method for Studying Stress-Strain Relations for Metal Thin Films on Silicon Substrates

    SciTech Connect

    Florando, J N; Nix, W D

    2004-02-12

    We have developed a microbeam bending technique for determining elastic-plastic, stress-strain relations for thin metal films on silicon substrates. The method is similar to previous microbeam bending techniques, except that triangular silicon microbeams are used in place of rectangular beams. The triangular beam has the advantage that the entire film on the top surface of the beam is subjected to a uniform state of plane strain as the beam is deflected, unlike the standard rectangular geometry where the bending is concentrated at the support. We present a method of analysis for determining two Ramberg-Osgood parameters for describing the stress-strain relation for the film. These parameters are obtained by fitting the elastic-plastic model to the measured load-displacement data, and utilizing the known elastic properties of both film and substrate. As a part of the analysis we compute the position of the neutral plane for bending, which changes as the film deforms plastically. This knowledge, in turn, allows average stress-strain relations to be determined accurately without forcing the film to closely follow the Ramberg-Osgood law. The method we have developed can be used to determine the elastic-plastic properties of thin metal films on silicon substrates up to strains of about 1%. Utilizing this technique, both yielding and strain hardening of Cu thin films on silicon substrates have been investigated. Copper films with dual crystallographic textures and different grain sizes, as well as others with strong <111> textures have been studied. Three strongly textured <111> films were studied to examine the effect of film thickness on the deformation properties of the film. These films show very high rates of work hardening, and an increase in the yield stress and work hardening rate with decreasing film thickness, consistent with current dislocation models.

  20. Tribological and thermal stability study of nanoporous amorphous boron carbide films prepared by pulsed plasma chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Liza, Shahira; Ohtake, Naoto; Akasaka, Hiroki; Munoz-Guijosa, Juan M.

    2015-06-01

    In this work, the thermal stability and the oxidation and tribological behavior of nanoporous a-BC:H films are studied and compared with those in conventional diamond-like carbon (DLC) films. a-BC:H films were deposited by pulsed plasma chemical vapor deposition using B(CH3)3 gas as the boron source. A DLC interlayer was used to prevent the a-BC:H film delamination produced by oxidation. Thermal stability of a-BC:H films, with no delamination signs after annealing at 500 °C for 1 h, is better than that of the DLC films, which completely disappeared under the same conditions. Tribological test results indicate that the a-BC:H films, even with lower nanoindentation hardness than the DLC films, show an excellent boundary oil lubricated behavior, with lower friction coefficient and reduce the wear rate of counter materials than those on the DLC film. The good materials properties such as low modulus of elasticity and the formation of micropores from the original nanopores during boundary regimes explain this better performance. Results show that porous a-BC:H films may be an alternative for segmented DLC films in applications where severe tribological conditions and complex shapes exist, so surface patterning is unfeasible.

  1. A study of the effects of lead foil in dental X-ray film packets on radiographic image quality.

    PubMed

    Araki, K; Kanda, S; Toyofuku, F

    1993-11-01

    The role of lead foil in protecting film from image degradation due to back-scattered radiation was studied. The effects of low-scattering (polystyrene foam) and tissue-equivalent (Lucite) materials on relative speed and modulation transfer factor (MTF) of the front and back films from Kodak DF-57 double film packets were evaluated. The relative speed of the back film with polystyrene foam behind the film was about 10% faster with lead foil. However, when Lucite was placed behind the film, lead foil eliminated the effect of scattered radiation on film density, MTF, was decreased by the presence of lead foil when polystyrene foam was placed behind the film. With Lucite, however, lead foil improved the MTF value, which was decreased by the scattered radiation at spatial frequencies over 5 cycle mm-1. These results suggest that lead foil itself causes scattered or secondary radiation and affects film speed and resolution. However, it also protects the film from scattered radiation from tissue behind the film and results in improvement in resolution. PMID:8181643

  2. Domain wall displacements in amorphous films and multilayers studied with a magnetic force microscope

    NASA Astrophysics Data System (ADS)

    Pokhil, Taras G.

    1997-04-01

    The magnetic force microscope (MFM) was used to study the displacement of domain walls (DW) in amorphous TbFe alloy films and Co/Pd multilayer films with high spatial resolution. The reversible bending of domain wall segments pinned to defects and irreversible, jumplike displacement of domain wall segments were imaged with the MFM in an applied magnetic field. The maximum reversible displacement of domain walls was 50-100 nm and the length of the segments which reversibly curved in the field was about 150 nm. Measurement of the change in radius of curvature of a DW segment in response to an applied field allowed estimation of the DW energy density and self-demagnetizing field of the film acting on the DW. The DW energy density for the TbFe films was about 1 erg/cm2. It was shown that the self-demagnetizing field acting on a domain wall depends on the domain structure surrounding the studied DW segment. For instance, for a film with saturation magnetization 100 G and thickness 80 nm, which exhibited a mazelike domain structure, the demagnetizing field varied from 100 G in the center of a mazelike domain to 400 G near the edge of a domain. The irreversible displacement of a DW was not a continuous process. The 200-400 nm long DW segments exhibited jumplike motion over distances of 100-150 nm.

  3. Systematic experimental study of pure shear type dielectric elastomer membranes with different electrode and film thicknesses

    NASA Astrophysics Data System (ADS)

    Hodgins, M.; Seelecke, S.

    2016-09-01

    An approach to reduce the voltage required for dielectric elastomer actuators is to reduce film thickness. However, if the electrode thickness is not similarly reduced, the electrode’s mechanical behavior can increasingly and negatively impact the overall actuator behavior. This effect is yet to be studied and quantified for pure shear type specimens; a type recommended in a recent DE standardization journal publication. Therefore, in this work, using pure shear specimens, a comparative study of membrane actuators of different film thickness (20, 50 and 100 μm) is performed. Electrodes of different thicknesses are screen printed and tested in a uniaxial test device. The stiffening effect due to the solid-state electrodes is demonstrated by performing force-elongation tests for specimens with and without electrodes. Additionally the importance of thin electrodes (relative to film thickness) was demonstrated through a number of electromechanical tests. Isotonic tests revealed a lower electro-mechanical sensitivity for the 20 μm film when compared with the 50 and 100 μm films. This was attributed to the relatively thick electrodes. Best actuation results were achieved when the total electrode thickness was at least 15x thinner than the dielectric membrane thickness.

  4. Optical spectroscopy and scanning tunneling microscopy studies of molecular adsorbates and anisotropic ultrathin films. Final report

    SciTech Connect

    Hemminger, J.C.

    1998-09-01

    The bonding, chemistry and ordering of molecular adsorbates on well defined single crystal surfaces and in ultrathin films was to be studied in an effort to develop sufficient fundamental understanding to allow the controlled preparation of anisotropic ultrathin films of organic monolayers. In this research the authors combine the use of optical probes (Raman spectroscopy, laser induced thermal desorption with Fourier transform mass spectrometry detection) with scanning tunneling microscopy (STM) and conventional methods of UHV surface science (Auger electron spectroscopy, x-ray photoelectron spectroscopy, low energy electron diffraction, and thermal desorption spectroscopy). The conventional surface probes provide well tested methods for the preparation and characterization of single crystal substrates. The optical probes used in the experiments provide powerful methods for the molecular identification of adsorbates in monolayers and ultrathin films. Scanning tunneling microscopy provides one with the ability to determine the detailed molecular level ordering of the molecular adsorbates. The emphasis of this research is on more complex molecular absorbates some of which are monomer precursors to ultrathin polymer films. Enhanced methods of Raman spectroscopy have been developed for the study of monolayer adsorbates on surfaces in ultrahigh vacuum environments. This report gives an overview of recent research results, including the construction of UHV variable temperature STM, analysis of STM images, growth and chemistry of intermetallic single crystal ultrathin films, and electron beam induced chemistry of tetracyanoquinodimethane.

  5. Molecular Study of Dynamic Behavior between Head and Ultrathin Lubricant Film

    NASA Astrophysics Data System (ADS)

    Liu, Xiangjun; Amemiya, Kensuke; Wong, Chee How; Yu, Shengkai; Liu, Bo

    The lubricant, perfluoropolyethers (PFPEs), has been modeled and analyzed using molecular dynamics simulations based on a coarse-grained bead-spring model. An ultrathin lubricant film with a thickness of 1-2 nm is coated on a disk to lubricate the head disk interface (HDI) of hard disk drives (HDDs). The retention performance of the lubricant film is studied, which is important to avoid a direct contact between the head and disk. The replenishment performance is also studied, which is essential to repair the lubricant film ruptured by a contact of the head. Finally, the typical phenomenon of touch down-take off hysteresis during the contact between head and disk is confirmed and analyzed because of the nanoscopic interactions in the HDI.

  6. Manipulating the Assembly of Spray-Deposited Nanocolloids: In Situ Study and Monolayer Film Preparation.

    PubMed

    Zhang, Peng; Santoro, Gonzalo; Yu, Shun; Vayalil, Sarathlal K; Bommel, Sebastian; Roth, Stephan V

    2016-05-01

    Fabrication of nanoparticle arrays on a substrate is one of the most concerned aspects for manipulating assembly of nanoparticles and preparing functional nanocomposites. Here, we studied in situ the assembly kinetics of polystyrene nanocolloids by using grazing incidence small-angle X-ray scattering. The structure formation of the nanoparticle film is monitored during air-brush spraying, which provides a rapid and scalable preparation. By optimizing the substrate temperature, the dispersion of the nanocolloids can be tailored to prepare monolayer film. The success of the monolayer preparations is attributed to the fast solvent evaporation which inhibits the aggregation of the nanocolloids. The present study may open a new avenue for the manufacture-friendly preparation of well-dispersed nanoparticle thin films. PMID:27070283

  7. Study of the microwave electrodynamic response of MgB 2 thin films

    NASA Astrophysics Data System (ADS)

    Andreone, A.; Cassinese, A.; Cantoni, C.; Di Gennaro, E.; Lamura, G.; Maglione, M. G.; Paranthaman, M.; Salluzzo, M.; Vaglio, R.

    2002-08-01

    We present a study on the power dependence of the microwave surface impedance in thin films of the novel superconductor MgB 2. 500 nm thick samples exhibiting critical temperatures ranging between 26 and 38 K are synthesized by an ex situ post-anneal of e-beam evaporated boron in the presence of an Mg vapor at 900 °C. Preliminary results on films grown in situ by a high rate magnetron sputtering technique from stoichiometric MgB 2 and Mg targets are also reported. Microwave measurements have been carried out employing a dielectrically loaded niobium superconducting cavity operating at 19.8 GHz and 4 K. The study shows that the electrodynamic response of MgB 2 films is presently dominated by extrinsic sources of dissipation, appearing already at low microwave power, likely to be ascribed to the presence of grain boundaries and normal inclusions in the samples.

  8. CCQM Pilot Study CCQM-P140: Quantitative surface analysis of multi-element alloy films

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Joong; Jang, Jong Shik; Kim, An Soon; Suh, Jung Ki; Chung, Yong-Duck; Hodoroaba, Vasile-Dan; Wirth, Thomas; Unger, Wolfgang; Kang, Hee Jae; Popov, Oleg; Popov, Inna; Kuselman, Ilya; Lee, Yeon Hee; Sykes, David E.; Wang, Meiling; Wang, Hai; Ogiwara, Toshiya; Nishio, Mitsuaki; Tanuma, Shigeo; Simons, David; Szakal, Christopher; Osborn, William; Terauchi, Shinya; Ito, Mika; Kurokawa, Akira; Fujimoto, Toshiyuki; Jordaan, Werner; Jeong, Chil Seong; Havelund, Rasmus; Spencer, Steve; Shard, Alex; Streeck, Cornelia; Beckhoff, Burkhard; Eicke, Axel; Terborg, Ralf

    2015-01-01

    A pilot study for a quantitative surface analysis of multi-element alloy films has been performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance (CCQM). The aim of this pilot study is to evaluate a protocol for a key comparison to demonstrate the equivalence of measures by National Metrology Institutes (NMIs) and Designated Institutes (DI) for the mole fractions of multi-element alloy films. A Cu(In,Ga)Se2 (CIGS) film with non-uniform depth distribution was chosen as a representative multi-element alloy film. The mole fractions of the reference and the test CIGS films were certified by isotope dilution—inductively coupled plasma/mass spectrometry. A total number counting (TNC) method was used as a method to determine the signal intensities of the constituent elements acquired in SIMS, XPS and AES depth profiling. TNC method is comparable with the certification process because the certified mole fractions are the average values of the films. The mole fractions of the CIGS films were measured by Secondary Ion Mass Spectrometry (SIMS), Auger Electron Spectroscopy (AES), X-ray Photoelectron Spectroscopy (XPS), X-Ray Fluorescence (XRF) Analysis and Electron Probe Micro Analysis (EPMA) with Energy Dispersive X-ray Spectrometry (EDX). Fifteen laboratories from eight NMIs, one DI, and six non-NMIs participated in this pilot study. The average mole fractions of the reported data showed relative standard deviations from 5.5 % to 6.8 % and average relative expanded uncertainties in the range from 4.52 % to 4.86 % for the four test CIGS specimens. These values are smaller than those in the key comparison CCQM-K67 for the measurement of mole fractions of Fe-Ni alloy films. As one result it can be stated that SIMS, XPS and AES protocols relying on the quantification of CIGS films using the TNC method are mature to be used in a CCQM key comparison. Main text. To reach the main text of this paper, click on Final Report. The

  9. A comparative study of physico-chemical properties of CBD and SILAR grown ZnO thin films

    SciTech Connect

    Jambure, S.B.; Patil, S.J.; Deshpande, A.R.; Lokhande, C.D.

    2014-01-01

    Graphical abstract: Schematic model indicating ZnO nanorods by CBD (Z{sub 1}) and nanograins by SILAR (Z{sub 2}). - Highlights: • Simple methods for the synthesis of ZnO thin films. • Comparative study of physico-chemical properties of ZnO thin films prepared by CBD and SILAR methods. • CBD outperforms SILAR method. - Abstract: In the present work, nanocrystalline zinc oxide (ZnO) thin films have been successfully deposited onto glass substrates by simple and economical chemical bath deposition (CBD) and successive ionic layer adsorption reaction (SILAR) methods. These films were further characterized for their structural, optical, surface morphological and wettability properties. The X-ray diffraction (XRD) patterns for both CBD and SILAR deposited ZnO thin films reveal the highly crystalline hexagonal wurtzite structure. From optical studies, band gaps obtained are 2.9 and 3.0 eV for CBD and SILAR deposited thin films, respectively. The scanning electron microscope (SEM) patterns show growth of well defined randomly oriented nanorods and nanograins on the CBD and SILAR deposited samples, respectively. The resistivity of CBD deposited films (10{sup 2} Ω cm) is lower than that of SILAR deposited films (10{sup 5} Ω cm). Surface wettability studies show hydrophobic nature for both films. From the above results it can be concluded that CBD grown ZnO thin films show better properties as compared to SILAR method.

  10. Impedance spectroscopy study with Ca(UO{sub 2}PO{sub 4}){sub 2}10.5H{sub 2}O films

    SciTech Connect

    Ramos-Barrado, J.R.; Benavente, J.; Bruque, S.; Martinez, M.

    1995-03-15

    Calcium uranyl phosphate (CaUP) films were prepared and characterized both chemically and structurally. The electrical behavior of the films, as a solid phase (dry film) and in contact with aqueous solutions of electrolytes containing the generating ions (wet film), was studied by impedance spectroscopy. These last measurements made it possible to determine the contribution of both the bulk film and film/electrolyte interface. For both dry and wet films, the equivalent circuits are a parallel combination of resistance and a nonideal capacitor. Temperature dependence of the impedance of the CAUP solid films was considered, while concentration dependence of the film resistance when it is in contact with the electrolyte solutions was determined. In this case, the contribution of both the bulk film and electrolyte/film interface to the total impedance was also studied.

  11. Nonlinear Optical Studies of the Sol-gel Derived Lithium Tetraborate Thin Film

    NASA Astrophysics Data System (ADS)

    Dhanuskodi, S.; Mohandoss, R.; Philip, Reji

    2011-10-01

    Lithium tetraborate, Li2B4O7 films on glass substrate were prepared by chemical solution decomposition (CSD) method. The spin coated film (2000 rpm, 20 sec) was preheated (200 °C, 20 min) and then annealed at different temperatures (450°-600 °C) to form polycrystalline Li2B4O7 film. By X-ray diffraction (XRD), the prominent planes are found to be (100), (113), (302) and (403). The result shows that the main component of the film is Li2B4O7 crystalline phase. A slow XRD scan was used to calculate the crystallite size (D) and the average crystallite size was found to be 178 nm. The lower cut off wavelength at 325 nm with 75% transparency was measured by the UV-Vis spectra and the spectral dependence of the optical constants (extinction coefficient (K), reflectance(R)) was estimated. The optical energy band gap was found to be 3.62 eV. The nonlinear optical properties were studied by Z-scan experiment using a Q-switched, Nd: YAG laser (532 nm, 7 ns). The nonlinear absorption coefficient (NLA) β was found to be -5.74×10-5 cm/W. Reverse saturable absorption (RSA) is due to the multi photon absorption process. The high value of β makes the film suitable for optical limiting applications.

  12. Study of stress in tensile nitrogen-plasma-treated multilayer silicon nitride films

    SciTech Connect

    Morin, Pierre; Raymond, Gaetan; Benoit, Daniel; Guiheux, Denis; Pantel, Roland; Volpi, Fabien; Braccini, Muriel

    2011-07-15

    The authors conducted a physico-chemical analysis of tensile sequential-nitrogen-plasma-treated silicon nitride films, which function as stressor liners in complementary metal oxide semiconductor (CMOS) technologies. These films are made of stacked nanometer-thick, plasma-enhanced, chemical vapor-deposited layers which were individually treated with N{sub 2}-plasma, to increase stress. This study allowed us to monitor the evolution of the films' chemical composition and stress as a function of process parameters such as deposition and post-N{sub 2}-plasma duration. Consistent with secondary ion mass spectroscopy (SIMS), transmission electron microscopy (TEM) and other physico-chemical analysis results, it was shown that the elementary component of the films can be modeled with a bi-layer consisting of an untreated slice at the bottom that is covered by a more tensile post-treated film. In addition, we observed that longer plasma treatments increase residual stress, SiN bond concentration and layer density, while reducing hydrogen content. The stress increase induced by the plasma treatment was shown to correlate with the increase in SiN bonds following a percolation mechanism that is linked to hydrogen dissociation. Kinetics laws describing both SiN bond generation and stress increase are proposed and it is demonstrated that stress increase follows first-order kinetics.

  13. Formation of Hydroxyl and Water Layers on MgO Films Studied with Ambient Pressure XPS

    SciTech Connect

    Newberg, J.T.; Starr, D.; Yamamoto, S.; Kaya, S.; Kendelewicz, T.; Mysak, E.R.; Porsgaard, S.; Salmeron, M.B.; Brown Jr., G.E.; Nilsson, A.; Bluhm, H.

    2011-01-01

    To understand the interaction of water with MgO(100), a detailed quantitative assessment of the interfacial chemistry is necessary. We have used ambient pressure X-ray photoelectron spectroscopy (XPS) to measure molecular (H{sub 2}O) and dissociative (OH) water adsorption on a 4 monolayer (ML) thick MgO(100)/Ag(100) film under ambient conditions. Since the entire 4 ML metal oxide (Ox) film is probed by XPS, the reaction of the MgO film with water can be quantitatively studied. Using a multilayer model (Model 1) that measures changes in Ox thickness from O 1s (film) and Ag 3d (substrate) spectra, it is shown that the oxide portion of the MgO film becomes thinner upon hydroxylation. A reaction mechanism is postulated in which the top-most layer of MgO converts to Mg(OH)2 upon dissociation of water. Based on this mechanism a second model (Model 2) is developed to calculate Ox and OH thickness changes based on OH/Ox intensity ratios from O 1s spectra measured in situ, with the known initial Ox thickness prior to hydroxylation. Models 1 and 2 are applied to a 0.15 Torr isobar experiment, yielding similar results for H{sub 2}O, OH and Ox thickness changes as a function of relative humidity.

  14. Reversible Morphology Control in Block Copolymer Films via Solvent Vapor Processing: An In Situ GISAXS study

    PubMed Central

    Paik, Marvin Y.; Bosworth, Joan K.; Smilges, Detlef-M.; Schwartz, Evan L.; Andre, Xavier; Ober, Christopher K.

    2010-01-01

    The real time changes occurring within films of cylinder-forming poly(α-methylstyrene-block-4-hydroxystyrene) (PαMS-b-PHOST) were monitored as they were swollen in tetrahydrofuran (THF) and acetone solvent vapors. In situ information was obtained by combining grazing incidence small angle X-ray scattering (GISAXS) with film thickness monitoring of the solvent vapor swollen films. We show that for self assembly to occur, the polymer thin film must surpass a swollen thickness ratio of 212% of its original thickness when swollen in THF vapors and a ratio of 268% for acetone vapor annealing. As the polymer becomes plasticized by solvent vapor uptake, the polymer chains must become sufficiently mobile to self assemble, or reorganize, at room temperature. Using vapors of a solvent selective to one of the blocks, in our case PHOST-selective acetone, an order-order transition occured driven by the shift in volume fraction. The BCC spherical phase assumed in the highly swollen state can be quenched by rapid drying. Upon treatment with vapor of a non-selective solvent, THF, the film maintained the cylindrical morphology suggested by its dry-state volume fraction. In situ studies indicate that self-assembly occurs spontaneously upon attaining the threshold swelling ratios. PMID:21116459

  15. Nanoindentation experiments for single-layer rectangular graphene films: a molecular dynamics study

    PubMed Central

    2014-01-01

    A molecular dynamics study on nanoindentation experiments is carried out for some single-layer rectangular graphene films with four edges clamped. Typical load–displacement curves are obtained, and the effects of various factors including indenter radii, loading speeds, and aspect ratios of the graphene film on the simulation results are discussed. A formula describing the relationship between the load and indentation depth is obtained according to the molecular dynamics simulation results. Young’s modulus and the strength of the single-layer graphene film are measured as about 1.0 TPa and 200 GPa, respectively. It is found that the graphene film ruptured in the central point at a critical indentation depth. The deformation mechanisms and dislocation activities are discussed in detail during the loading-unloading-reloading process. It is observed from the simulation results that once the loading speed is larger than the critical loading speed, the maximum force exerted on the graphene film increases and the critical indentation depth decreases with the increase of the loading speed. PMID:24447765

  16. Terahertz ellipsometry study of the soft mode behavior in ultrathin SrTiO3 films

    NASA Astrophysics Data System (ADS)

    Marsik, P.; Sen, K.; Khmaladze, J.; Yazdi-Rizi, M.; Mallett, B. P. P.; Bernhard, C.

    2016-02-01

    We present a combined study with time-domain terahertz and conventional far-infrared ellipsometry of the temperature dependent optical response of SrTiO3 thin films (82 and 8.5 nm) that are grown by pulsed-laser deposition on (La0.3Sr0.7)(Al0.65Ta0.35)O3 (LSAT) substrates. We demonstrate that terahertz ellipsometry is very sensitive to the optical response of these thin films, in particular, to the soft mode of SrTiO3. We show that for the 82 nm film the eigenfrequency of the soft mode is strongly reduced by annealing at 1200 °C, whereas for the 8.5 nm film it is hardly affected. For the latter, after annealing the mode remains at 125 cm-1 at 300 K and exhibits only a weak softening to about 90 cm-1 at 10 K. This suggests that this ultrathin film undergoes hardly any relaxation of the compressive strain due to the LSAT substrate.

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

    SciTech Connect

    Mohri, Maryam; Nili-Ahmadabadi, Mahmoud; Chakravadhanula, Venkata Sai Kiran

    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.

  18. Spectroellipsometric studies of sol-gel derived Sr0.6Ba0.4Nb2O6 films

    NASA Astrophysics Data System (ADS)

    Ho, Melanie M. T.; Tang, T. B.; Mak, C. L.; Pang, G. K. H.; Chan, K. Y.; Wong, K. H.

    2006-10-01

    Sr0.6Ba0.4Nb2O6 (SBN) films have been fabricated on (001)Si substrates by a sol-gel technique. The annealing process was carried out in air at various temperatures ranging from 200to700°C. Studies using x-ray diffractometry, high resolution transmission electron microscopy, and scanning electron microscopy showed that polycrystalline films, with a grain size of about 100nm, were obtained only for annealing temperatures ⩾600°C. The optical properties of these sol-gel derived SBN films were studied by spectroscopic ellipsometry (SE). In the analysis of the measured SE spectra, a triple-layer Lorentz model has been developed and used to deduce the optical properties of the SBN films. Our systematic SE measurements revealed that the refractive indices of the SBN films increase with the annealing temperature. This increase is more pronounced at around the crystallization temperature, i.e., between 500 and 600°C. The extinction coefficients of the films also exhibit a similar trend, showing a zero value for amorphous films and larger values for films annealed at above 600°C. Our results demonstrate that while crystallization helps to raise the refractive index of the film due to film densification, it also promotes scattering by grain boundary, resulting in a larger extinction coefficient.

  19. A Study of the Electrotransport in Thin Films: An Advanced Method for the Study of Electrotransport in Thin Films Using Electrical Resistance Measurements

    NASA Technical Reports Server (NTRS)

    Hummel, R. E.; Slippy, W. A., Jr.

    1970-01-01

    To date, very little is understood about electrotransport in thin films. One reason for this is the lack of methods in which electromigration can be adequately monitored dynamically. In this thesis, a new nondestructive method for the study of the electrotransport phenomenon in thin aluminum films is presented. This method makes use of electrical resistance measurements of various regions along the test sample to monitor changes in resistance resulting from electromigration. The advantage of this method is that resistance changes can be observed long before void formation can be seen using standard microscopy methods. In order to achieve the best efficiency using this method, special consideration must be given to the design of the sample. Design problems and their respective solutions are given. The results of the electrical resistance measurements are interpreted by means of photographs taken with an scanning electron microscope. The increase in resistance of the aluminum samples is interpreted to be due to void formation. The expected decrease in resistance near the anode was never observed. It is shown that mass accumulation takes on the form of hillocks and whiskers on the surface of the aluminum film, which does not contribute appreciably to conductivity.

  20. Studying effect of MHD on thin films of a micropolar fluid

    NASA Astrophysics Data System (ADS)

    Abdel-Rahman, Gamal M.

    2009-11-01

    This paper deals with the study of the effect of MHD on thin films of a micropolar fluid. These thin films are considered for three different geometries, namely: (i) flow down an inclined plane, (ii) flow on a moving belt and (iii) flow down a vertical cylinder. The transformed boundary layer governing equations of a micropolar fluid and the resulting system of coupled non-linear ordinary differential equations are solved numerically by using shooting method. Numerical results were presented for velocity and micro-rotation profiles within the boundary layer for different parameters of the problem including micropolar fluid parameters, magnetic field parameter, etc., which are also discussed numerically and illustrated graphically.

  1. Atomic force microscope studies of fullerene films - Highly stable C60 fcc (311) free surfaces

    NASA Technical Reports Server (NTRS)

    Snyder, Eric J.; Tong, William M.; Williams, R. S.; Anz, Samir J.; Anderson, Mark S.

    1991-01-01

    Atomic force microscopy and X-ray diffractometry were used to study 1500 A-thick films of pure C60 grown by sublimation in ultrahigh vacuum onto a CaF2 (111) substrte. Topographs of the films did not reveal the expected close-packed structures, but they showed instead large regions that correspond to a face-centered cubic (311) surface and distortions of this surface. The open (311) structure may have a relatively low free energy because the low packing density contributes to a high entropy of the exposed surface.

  2. Electrical and photoconductivity studies on AgSbSe2 thin films

    NASA Astrophysics Data System (ADS)

    Namitha Asokan, T.; Urmila, K. S.; Pradeep, B.

    2015-02-01

    Silver antimony selenide thin films have been deposited on ultrasonically cleaned glass substrate at a vacuum of 10-5 torr using reactive evaporation technique. The preparative parameters like substrate temperature and incident fluxes have been properly controlled in order to get highly reproducible compound films. The polycrystalline nature of the sample is confirmed using XRD. The dependence of the electrical conductivity on the temperature has also been studied. The prepared AgSbSe2 samples show p-type conductivity. The samples show a little photoresponse.

  3. High speed cine film studies of plasma behaviour and plasma surface interactions in tokamaks

    NASA Astrophysics Data System (ADS)

    Goodall, D. H. J.

    1982-12-01

    High speed cine photography is a useful diagnostic aid for studying plasma behaviour and plasma surface interactions. Several workers have filmed discharges in tokamaks including ASDEX, DITE, DIVA, ISX, JFT2, TFR and PLT. These films are discussed and examples given of the observed phenomena which include plasma limiter interactions, diverted discharges, disruptions, magnetic islands and moving glowing objects often known as 'UFOs'. Examples of plasma structures in ASDEX and DITE not previously published are also given. The paper also reports experiments in DITE to determine the origin of UFOs.

  4. Silicon-sheet and thin-film cell and module technology potential: Issue study

    NASA Technical Reports Server (NTRS)

    Shimada, K.; Costogue, E. N.; Ferber, R. R.

    1984-01-01

    The development of high-efficiency low-cost crystalline silicon ribbon and thih-film solar cells for the energy national photovoltaics program was examined. The findings of an issue study conducted are presented. The collected data identified the status of the technology, future research needs, and problems experienced. The potentials of present research activities to meet the Federal/industry long-term technical goal of achieving 15 cents per kilowatt-hour levelized PV energy cost are assessed. Recommendations for future research needs related to crystalline silicon ribbon and thin-film technologies for flat-plate collectors are also included.

  5. Study of the leakage field of magnetic force microscopy thin-film tips using electron holography

    SciTech Connect

    Frost, B.G.; van Hulst, N.F.; Lunedei, E.; Matteucci, G.

    1996-03-01

    Electron holography is applied for the study of the leakage field of thin-film ferromagnetic tips used as probes in magnetic force microscopy. We used commercially available pyramidal tips covered on one face with a thin NiCo film, which were then placed in a high external magnetic field directed along the pyramid axis. Good agreement between simulated and experimental electron phase difference maps allows to measure the local flux from the ferromagnetic tips and therefore to evaluate the perturbation induced by the microprobe stray field on the sample area. {copyright} {ital 1996 American Institute of Physics.}

  6. Studies on the dynamic characteristics of gas film bearings and dampers

    NASA Technical Reports Server (NTRS)

    Stiffler, A. K.

    1975-01-01

    The dynamic characteristics of inherently compensated gas film bearings have been investigated for small excursion ratios. Both circular and rectangular cases have been solved for the stiffness and damping as a function of supply pressure, restrictor coefficient, and squeeze number. The effect of disturbance amplitude has been studied for the inherently compensated strip. Analytical solutions for the simple gas film damper problem have established the effect of disturbance amplitude at low squeeze numbers. These results are applicable to pressurized bearings as limiting case of the restrictor coefficient.

  7. Free-focus radiography using conventional films: Radiation exposures in a simulated clinical study

    SciTech Connect

    Jensen, T.W.; Randall, G.J.; Goldberg, A.J.

    1980-07-01

    This study compared air exposures during conventional dental and maxillofacial radiography and similar views using free-focus radiography with conventional image receptors. The results show that periapical type surveys on nonscreen film placed extraorally or in the buccal fold may be carried out with an exposure to the surface tissues, which is similar to or less than conventional dental radiography. Extraoral survey type radiographs of the jaws may be carried out with significantly less surface exposure than lateral oblique views of the jaws. The least exposure was required, when the film was placed in the buccla fold instead of against the face during free-focus radiography. The exposures with film screen combinations were reduced by an order of magnitude when compared to the nonscreen techniques. Proper filtration of the beam of the miniaturized x-ray machines radiography in dentistry may thus be desirable and applications in other parts of the body encouraged.

  8. Thickness effect on magnetocrystalline anisotropy of Co/Pd(111) films: A density functional study

    NASA Astrophysics Data System (ADS)

    Jekal, Soyoung; Rhim, S. H.; Kwon, Oryong; Hong, Soon Cheol

    2015-05-01

    In this study, we carried out first-principles calculations on magnetocrystalline anisotropy (MCA) of Co/Pd thin films by adopting two different systems of (i) n-Co/3-Pd and (ii) n-Pd/3-Co. In one system, we vary the thickness of Co layer, fixing the thickness of the Pd layer to 3-monolayers, and in the other system vice versa. MCA is mainly governed by the surface and interface Co atoms, while contributions from other Co atoms are smaller. MCA energy (EMCA) of the Co/Pd thin film shows oscillatory behavior with the thickness of the Co layer, but is insensitive to the thickness of the Pd layer. In particular, the n-Co/3-Pd films of n = 2, 4, and 6 exhibit strong perpendicular MCA of about 1 meV. Our results suggest that controlling the thickness of the Co layer in Co/Pd (111) is crucial in achieving strong perpendicular MCA.

  9. Brillouin light scattering study of spin waves in NiFe/Co exchange spring bilayer films

    SciTech Connect

    Haldar, Arabinda; Banerjee, Chandrima; Laha, Pinaki; Barman, Anjan

    2014-04-07

    Spin waves are investigated in Permalloy(Ni{sub 80}Fe{sub 20})/Cobalt(Co) exchange spring bilayer thin films using Brillouin light scattering (BLS) experiment. The magnetic hysteresis loops measured by magneto-optical Kerr effect show a monotonic decrease in coercivity of the bilayer films with increasing Py thickness. BLS study shows two distinct modes, which are modelled as Damon-Eshbach and perpendicular standing wave modes. Linewidths of the frequency peaks are found to increase significantly with decreasing Py layer thickness. Interfacial roughness causes to fluctuate exchange coupling at the nanoscale regimes and the effect is stronger for thinner Py films. A quantitative analysis of the magnon linewidths shows the presence of strong local exchange coupling field which is much larger compared to macroscopic exchange field.

  10. Mössbauer and SEM study of Fe-Al film

    NASA Astrophysics Data System (ADS)

    Sebastian, Varkey; Sharma, Ram Kripal; Lakshmi, N.; Venugopalan, K.

    Fe-Al alloy with Fe/Al ratio of 3:1 was first prepared by argon arc melting. It was subsequently coated on glass slide and cellophane tape using an electron beam gun system to have a thickness of 2,000 Å. X-ray diffraction spectrum of the coated sample indicates a definite texture for the film with a preferential growth along the Fe(110) plane. SEM micrographs of the film showed the presence of nano islands of nearly 3 x 1012/m2 surface density. Composition of different parts of the film was determined using EDAX. Room temperature Fe-57 Mössbauer spectrum of coated sample showed the presence a quadrupole doublet with a splitting of 0.46 mm/s, which is typical of Al-rich iron compounds. MOKE study shows an in-plane magnetic moment.

  11. Thin film of lignocellulosic nanofibrils with different chemical composition for QCM-D study.

    PubMed

    Kumagai, Akio; Lee, Seung-Hwan; Endo, Takashi

    2013-07-01

    Thin films of lignocellulosic nanofibrils (LCNFs) with different chemical compositions were prepared for real-time observation of their enzymatic adsorption and degradation behavior by using a quartz crystal microbalance with dissipation monitoring (QCM-D). LCNFs were obtained by disk milling followed by high-pressure homogenization of Hinoki cypress. The lignin contents were adjusted by the sodium chlorite treatment. The film thickness was adjusted by controlling the concentration of the LCNF suspension, which was determined from its proportional relationship to the UV absorbance of lignin. The enzymatic degradation behavior was investigated with a commercial enzyme mixture. The results of the QCM-D showed that changes in frequency and dissipation in the initial reaction stage were different from the typical changes reported for pure cellulose. To the best of our knowledge, this is the first report of the preparation of thin films of LCNFs with high lignin and hemicellulose contents and their application in a QCM-D study. PMID:23721319

  12. Biomolecular papain thin films grown by matrix assisted and conventional pulsed laser deposition: A comparative study

    NASA Astrophysics Data System (ADS)

    György, E.; Pérez del Pino, A.; Sauthier, G.; Figueras, A.

    2009-12-01

    Biomolecular papain thin films were grown both by matrix assisted pulsed laser evaporation (MAPLE) and conventional pulsed laser deposition (PLD) techniques with the aid of an UV KrF∗ (λ =248 nm, τFWHM≅20 ns) excimer laser source. For the MAPLE experiments the targets submitted to laser radiation consisted on frozen composites obtained by dissolving the biomaterial powder in distilled water at 10 wt % concentration. Conventional pressed biomaterial powder targets were used in the PLD experiments. The surface morphology of the obtained thin films was studied by atomic force microscopy and their structure and composition were investigated by Fourier transform infrared spectroscopy. The possible physical mechanisms implied in the ablation processes of the two techniques, under comparable experimental conditions were identified. The results showed that the growth mode, surface morphology as well as structure of the deposited biomaterial thin films are determined both by the incident laser fluence value as well as target preparation procedure.

  13. Compositional and Structural Study of Gd Implanted ZnO Films

    SciTech Connect

    Murmu, Peter P.; Kennedy, John V.; Markwitz, Andreas; Ruck, Ben J.

    2009-07-23

    We report a compositional and structural study of ZnO films implanted with 30 keV Gd ions. The depth profile of the implanted ions, measured by Rutherford backscattering spectrometry, matches predictions of DYNAMIC-TRIM calculations. However, after annealing at temperatures above 550 deg. C the Gd ions are observed to migrate towards the bulk, and at the same time atomic force microscope images of the film surfaces show significant roughening. Raman spectroscopy shows that the annealed films have a reduced number of crystalline defects. The overall results are useful for developing an implantation-annealing regime to produce well characterized samples to investigate magnetism in the ZnO:Gd system.

  14. Free-focus radiography using conventional films--radiation exposures in a simulated clinical study.

    PubMed

    Jensen, T W; Randall, G J; Goldberg, A J

    1980-01-01

    This study compared air exposures during conventional dental and maxillofacial radiography and similar views using free-focus radiography with conventional image receptors. The results show that periapical type surveys on nonscreen film placed extraorally or in the buccal fold may be carried out with an exposure to the surface tissues, which is similar to or less than conventional dental radiography. Extraoral survey type radiographs of the jaws may be carried out with significantly less surface exposure than lateral oblique views of the jaws. The least exposure was required, when the film was placed in the buccla fold instead of against the face during free-focus radiography. The exposures with film screen combinations were reduced by an order of magnitude when compared to the nonscreen techniques. Proper filtration of the beam of the miniaturized x-ray machines radiography in dentistry may thus be desirable and applications in other parts of the body encouraged. PMID:7393160

  15. Numerical study of boundary layer transition in flowing film evaporation on horizontal elliptical cylinder

    NASA Astrophysics Data System (ADS)

    Asbik, M.; Ansari, O.; Zeghmati, B.

    2005-03-01

    A numerical study of the onset of longitudinal transition between turbulent and laminar regimes during the evaporation of a water film is presented. These water film streams along a horizontal elliptical tube under the simultaneous effects of gravity, pressure gradients, caused by the vapor flow and curvature, and viscous forces. At the interface of water vapor, the shear stress is supposed to be negligible. Outside the boundary layer, the vapor phase velocity is obtained from potential flow. In the analysis Von Karman’s turbulence model is used and the inertia and convection terms are retained. Transfers equations are discretised by using the implicit Keller method. The effects of an initial liquid flow rate per unit of length, Froude number, temperature difference between the wall and the liquid vapor interface and ellipticity on the transition position have been evaluated. The transition criterion has been given in term of the critical film Reynolds number (ReΓ)C.

  16. Molecular dynamics in azobenzene liquid crystal polymer films studied by transient grating technique

    NASA Astrophysics Data System (ADS)

    Katayama, Kenji; Fujii, Tomomi; Kuwahara, Shota; Takado, Kiyohide; Ikeda, Tomiki

    2014-10-01

    We studied the effect of the ratio between the monomer and cross-linker molecules in the azobenene included liquid crystal polymer films by using the heterodyne transient grating (HD-TG) technique, which is one of the time-resolved measurement techniques. Depending on the ratio, the magnitude of the refractive index change, its anisotropy, and the lifetime of the cis isomer of azobenzene, generated by a UV pulse irradiation. By increasing the cross-linker ratio, the refractive index change and its anisotropy was reduced, indicating less ability for the motion, while slower lifetime was observed by increasing the monomer ratio, indicating that the film is difficult to return the original shape by a visiblelight irradiation. The obtained dynamics was consistent with the functionality of the films.

  17. Comparative study of the biodegradability of porous silicon films in simulated body fluid.

    PubMed

    Peckham, J; Andrews, G T

    2015-01-01

    The biodegradability of oxidized microporous, mesoporous and macroporous silicon films in a simulated body fluid with ion concentrations similar to those found in human blood plasma were studied using gravimetry. Film dissolution rates were determined by periodically weighing the samples after removal from the fluid. The dissolution rates for microporous silicon were found to be higher than those for mesoporous silicon of comparable porosity. The dissolution rate of macroporous silicon was much lower than that for either microporous or mesoporous silicon. This is attributed to the fact that its specific surface area is much lower than that of microporous and mesoporous silicon. Using an equation adapted from [Surf. Sci. Lett. 306 (1994), L550-L554], the dissolution rate of porous silicon in simulated body fluid can be estimated if the film thickness and specific surface area are known. PMID:25585985

  18. Compositional study of vacuum annealed Al doped ZnO thin films obtained by RF magnetron sputtering

    SciTech Connect

    Shantheyanda, B. P.; Todi, V. O.; Sundaram, K. B.; Vijayakumar, A.; Oladeji, I.

    2011-09-15

    Aluminum doped zinc oxide (AZO) thin films were obtained by RF magnetron sputtering. The effects of deposition parameters such as power, gas flow conditions, and substrate heating have been studied. Deposited and annealed films were characterized for composition as well as microstructure using x ray photoelectron spectroscopy and x ray diffraction. Films produced were polycrystalline in nature. Surface imaging and roughness studies were carried out using SEM and AFM, respectively. Columnar grain growth was predominantly observed. Optical and electrical properties were evaluated for transparent conducting oxide applications. Processing conditions were optimized to obtain highly transparent AZO films with a low resistivity value of 6.67 x 10{sup -4}{Omega} cm.

  19. Use of a sandwich technique to control image geometry in clinical studies comparing intraoral xeroradiographs and E-speed films

    SciTech Connect

    Ludlow, J.B.; Hill, R.A.; Hayes, C.J.

    1988-05-01

    A method of superimposing a film on a xeroradiographic (XR) cassette for simultaneous intraoral exposure is evaluated for use as an imaging technique in clinical studies comparing Ektaspeed film and XR images. Sandwich images were indistinguishable from those produced by conventional technique. Pilot studies were conducted with 104 patients who had symptomatic dental problems. No significant differences were found in diagnostic usefulness or image quality between XR and film radiographs when sign test analysis was used. The sandwich technique yielded film and XR images with duplicate image geometry while reducing patient exposures to one half of that used in conventional image comparison protocols.

  20. The Arts in Contemporary South African Higher Education: Film and Media Studies

    ERIC Educational Resources Information Center

    Rijsdijk, Ian-Malcolm

    2016-01-01

    Twenty years after South Africa's first democratic elections, what is the state of film and media studies education at the country's higher education institutions? The article examines several key debates, from calls for the decolonisation of curricula to the tension between internationalisation and local research in local media industries. Is…

  1. Could Audio-Described Films Benefit from Audio Introductions? An Audience Response Study

    ERIC Educational Resources Information Center

    Romero-Fresco, Pablo; Fryer, Louise

    2013-01-01

    Introduction: Time constraints limit the quantity and type of information conveyed in audio description (AD) for films, in particular the cinematic aspects. Inspired by introductory notes for theatre AD, this study developed audio introductions (AIs) for "Slumdog Millionaire" and "Man on Wire." Each AI comprised 10 minutes of…

  2. Growth of Co films on Cu(111) studied in real space

    NASA Astrophysics Data System (ADS)

    Hochstrasser, M.; Zurkirch, M.; Wetli, E.; Pescia, D.; Erbudak, M.

    1994-12-01

    The atomic structure of Co films deposited on Cu(111) at room temperature is studied by imaging backscattered secondary electrons. The patterns show in-registry growth for the first two atomic layers. The next two monolayers show features of the fcc as well as the hcp structure. The hexagonal structure characteristic for bulk Co is found for subsequent layers.

  3. A Diary Study of University EFL Learners' Intercultural Learning through Foreign Films

    ERIC Educational Resources Information Center

    Chao, Tzu-Chia

    2013-01-01

    With the global spread and use of English, Teaching English to Speakers of Other Languages (TESOL) professionals have become increasingly interested in intercultural learning. Comparatively few studies have been published, however, on the use of films in intercultural learning within the context of English as a foreign language (EFL) curricula in…

  4. Film Evaluations of Eskimo Education. The National Study of American Indian Education, Series III, No. 4, Final Report.

    ERIC Educational Resources Information Center

    Collier, John, Jr.

    As a part of the Final Report of the National Study of American Indian Education, the educational environments of schools in 2 Alaskan tundra villages, in a state-consolidated school in Bethel, and in Anchorage public schools were filmed to provide empirical evidence for the evaluation of Eskimo education. This film study was pointed toward…

  5. A study of Ti-doped WO3 thin films using comparative theoretical and experimental approach

    NASA Astrophysics Data System (ADS)

    Paez, Aurelio

    Metal oxides like Tungsten Oxide (WO3) are well documented and characterized in the literature, with uses in darkening windows and mirrors, flat computer displays, solar panel cooling, and sensors (of interest in this study). Ti doping of WO3 is less documented and the focus of this study. Sample thin films of pure WO3 and varyingly Ti doped WO3 were prepared using Radio Frequency magnetron sputtering (RF) (13.56 MHz) to grow thin films on a silicon substrate. This study aims to compare multiple Ti doping percentages in WO3 theoretically and then compare with experimental data taken from thin films of various Ti doping levels grown at temperatures ranging from room temperature to 400 0°C. Characterization of the materials was to be conducted using Fourier Transform Infrared Spectroscopy, Raman Spectroscopy, X-ray diffraction, and other theoretical and simulated approaches. Theoretical calculations optimized Ti doping at somewhere between 6.25% and 12%. Experimental data indicates that under the given growing conditions optimal Ti doping is 5%. The percentage of Ti may be able to be increased and the material retain desired characteristics with an increased growth temperature above 400 0°C as annealing samples post-growth has no positive impact on the thin film structure.

  6. Positron beam and RBS studies of thermally grown oxide films on stainless steel grade 304

    NASA Astrophysics Data System (ADS)

    Horodek, P.; Siemek, K.; Kobets, A. G.; Kulik, M.; Meshkov, I. N.

    2015-04-01

    The formation of oxide films on surfaces of stainless steel 304 AISI annealed at 800 °C in vacuum, air and in flow N2 atmospheres was studied using variable energy positron beam technique (VEP) and Rutherford backscattering/nuclear reaction (RBS/NR) methods. In frame of these studies, Doppler broadening of annihilation line (DB) measurements were performed. For a sample heated in vacuum the oxide film ca. 8 nm is observed. For specimens oxidized in air and N2 the multi-layered oxide films of about a few hundred nanometers are recognized. The RBS/NR measurements have shown that the sample annealed in vacuum contains a lower quantity of oxygen while for samples heated in the air and N2 non-linear and rather linear time-dependency are observed, respectively. The thicknesses of total oxide films obtained from RBS/NR tests are in good agreement with the VEP results. Time evolution of the oxide growing was studied as well.

  7. Application of an Electrochemical Quartz Crystal Microbalance to the study of electrocatalytic films

    SciTech Connect

    Gordon, J.S. Jr.

    1993-09-01

    The EQCM was used to study the deposition and composition of electrodeposited pure PbO{sub 2} and Bi-doped PbO{sub 2} active toward anodic oxygen-transfer reactions. Within the doped films, Bi is incorporated as Bi{sup +5} in the form of BiO{sub 2}A, where A is ClO{sub 4}{sup {minus}} or NO{sub 3}{sup {minus}}. For deposition of these 2 materials, changes in hydration between the Au oxide and the depositing film resulted in higher mass-to-charge ratios. XRD and XPS were used to study the films; the rutile structure of PbO{sub 2} is retained even with the Bi doping. The EQCM was also used to study the formation and dissolution of Au oxide and preoxide structures formed on the Au substrate electrodes in acidic media. The preoxide structures were AuOH and increased the surface mass. For the formation of stable Au films on quartz wafers, Ti interlayers between Au and quartz was found to be very effective.

  8. Studies on methylcellulose/pectin/montmorillonite nanocomposite films and their application possibilities.

    PubMed

    Saha, Nayan Ranjan; Sarkar, Gunjan; Roy, Indranil; Rana, Dipak; Bhattacharyya, Amartya; Adhikari, Arpita; Mukhopadhyay, Asis; Chattopadhyay, Dipankar

    2016-01-20

    Films based on methylcellulose (MC) and pectin (PEC) of different ratios were prepared. MC/PEC (90:10) (MP10) gave the best results in terms of mechanical properties. Sodium montmorillonite (MMT) (1, 3 and 5 wt%) was incorporated in the MP10 matrix. The resulting films were characterized by X-ray diffraction and transmission electron microscopy, and it was found that nanocomposites were intercalated in nature. Mechanical studies established that addition of 3 wt% MMT gave best results in terms of mechanical properties. However, thermo-gravimetric and dynamic mechanical analysis proved that decomposition and glass transition temperature increased with increasing MMT concentration from 1 to 5 wt%. It was also observed that moisture absorption and water vapor permeability studies gave best result in the case of 3 wt% MMT. Optical clarity of the nanocomposite films was not much affected with loading of MMT. In vitro drug release studies showed that MC/PEC/MMT based films can be used for controlled transdermal drug delivery applications. PMID:26572465

  9. Demonstration of thin film pair distribution function analysis (tfPDF) for the study of local structure in amorphous and crystalline thin films.

    PubMed

    Jensen, Kirsten M Ø; Blichfeld, Anders B; Bauers, Sage R; Wood, Suzannah R; Dooryhée, Eric; Johnson, David C; Iversen, Bo B; Billinge, Simon J L

    2015-09-01

    By means of normal-incidence, high-flux and high-energy X-rays, total scattering data for pair distribution function (PDF) analysis have been obtained from thin films (tf), suitable for local structure analysis. By using amorphous substrates as support for the films, the standard Rapid Acquisition PDF setup can be applied and the scattering signal from the film can be isolated from the total scattering data through subtraction of an independently measured background signal. No angular corrections to the data are needed, as would be the case for grazing incidence measurements. The 'tfPDF' method is illustrated through studies of as-deposited (i.e. amorphous) and crystalline FeSb3 films, where the local structure analysis gives insight into the stabilization of the metastable skutterudite FeSb3 phase. The films were prepared by depositing ultra-thin alternating layers of Fe and Sb, which interdiffuse and after annealing crystallize to form the FeSb3 structure. The tfPDF data show that the amorphous precursor phase consists of corner-sharing FeSb6 octahedra with motifs highly resembling the local structure in crystalline FeSb3. Analysis of the amorphous structure allows the prediction of whether the final crystalline product will form the FeSb3 phase with or without excess Sb present. The study thus illustrates how analysis of the local structure in amorphous precursor films can help to understand crystallization processes of metastable phases and opens for a range of new local structure studies of thin films. PMID:26306190

  10. Demonstration of thin film pair distribution function analysis (tfPDF) for the study of local structure in amorphous and crystalline thin films

    DOE PAGESBeta

    Jensen, K. M.Ø.; Blichfeld, A. B.; Bauers, S. R.; Wood, S. R.; Dooryhee, E.; Johnson, D. C.; Iversen, B. B.; Billinge, S.

    2015-07-05

    By means of normal incidence, high flux and high energy x-rays, we have obtained total scattering data for Pair Distribution Function (PDF) analysis from thin films (tf), suitable for local structure analysis. By using amorphous substrates as support for the films, the standard Rapid Acquisition PDF setup can be applied and the scattering signal from the film can be isolated from the total scattering data through subtraction of an independently measured background signal. No angular corrections to the data are needed, as would be the case for grazing incidence measurements. We illustrate the ‘tfPDF’ method through studies of as depositedmore » (i.e. amorphous) and crystalline FeSb3 films, where the local structure analysis gives insight into the stabilization of the metastable skutterudite FeSb3 phase. The films were prepared by depositing ultra-thin alternating layers of Fe and Sb, which interdiffuse and after annealing crystallize to form the FeSb3 structure. The tfPDF data show that the amorphous precursor phase consists of corner-sharing FeSb6 octahedra with motifs highly resembling the local structure in crystalline FeSb3. Analysis of the amorphous structure allows predicting whether the final crystalline product will form the FeSb3 phase with or without excess Sb present. The study thus illustrates how analysis of the local structure in amorphous precursor films can help to understand crystallization processes of metastable phases and opens for a range of new local structure studies of thin films.« less

  11. Demonstration of thin film pair distribution function analysis (tfPDF) for the study of local structure in amorphous and crystalline thin films

    SciTech Connect

    Jensen, K. M.Ø.; Blichfeld, A. B.; Bauers, S. R.; Wood, S. R.; Dooryhee, E.; Johnson, D. C.; Iversen, B. B.; Billinge, S.

    2015-07-05

    By means of normal incidence, high flux and high energy x-rays, we have obtained total scattering data for Pair Distribution Function (PDF) analysis from thin films (tf), suitable for local structure analysis. By using amorphous substrates as support for the films, the standard Rapid Acquisition PDF setup can be applied and the scattering signal from the film can be isolated from the total scattering data through subtraction of an independently measured background signal. No angular corrections to the data are needed, as would be the case for grazing incidence measurements. We illustrate the ‘tfPDF’ method through studies of as deposited (i.e. amorphous) and crystalline FeSb3 films, where the local structure analysis gives insight into the stabilization of the metastable skutterudite FeSb3 phase. The films were prepared by depositing ultra-thin alternating layers of Fe and Sb, which interdiffuse and after annealing crystallize to form the FeSb3 structure. The tfPDF data show that the amorphous precursor phase consists of corner-sharing FeSb6 octahedra with motifs highly resembling the local structure in crystalline FeSb3. Analysis of the amorphous structure allows predicting whether the final crystalline product will form the FeSb3 phase with or without excess Sb present. The study thus illustrates how analysis of the local structure in amorphous precursor films can help to understand crystallization processes of metastable phases and opens for a range of new local structure studies of thin films.

  12. Demonstration of thin film pair distribution function analysis (tfPDF) for the study of local structure in amorphous and crystalline thin films

    PubMed Central

    Jensen, Kirsten M. Ø.; Blichfeld, Anders B.; Bauers, Sage R.; Wood, Suzannah R.; Dooryhée, Eric; Johnson, David C.; Iversen, Bo B.; Billinge, Simon J. L.

    2015-01-01

    By means of normal-incidence, high-flux and high-energy X-rays, total scattering data for pair distribution function (PDF) analysis have been obtained from thin films (tf), suitable for local structure analysis. By using amorphous substrates as support for the films, the standard Rapid Acquisition PDF setup can be applied and the scattering signal from the film can be isolated from the total scattering data through subtraction of an independently measured background signal. No angular corrections to the data are needed, as would be the case for grazing incidence measurements. The ‘tfPDF’ method is illustrated through studies of as-deposited (i.e. amorphous) and crystalline FeSb3 films, where the local structure analysis gives insight into the stabilization of the metastable skutterudite FeSb3 phase. The films were prepared by depositing ultra-thin alternating layers of Fe and Sb, which interdiffuse and after annealing crystallize to form the FeSb3 structure. The tfPDF data show that the amorphous precursor phase consists of corner-sharing FeSb6 octahedra with motifs highly resembling the local structure in crystalline FeSb3. Analysis of the amorphous structure allows the prediction of whether the final crystalline product will form the FeSb3 phase with or without excess Sb present. The study thus illustrates how analysis of the local structure in amorphous precursor films can help to understand crystallization processes of metastable phases and opens for a range of new local structure studies of thin films. PMID:26306190

  13. [Study on the Properties of the Pc-Si Films Prepared by Magnetron Co-Sputtering at Low Temperature].

    PubMed

    Duan, Liang-fei; Yang, Wen; Zhang, Li-yuan; Li, Xue-ming; Chen, Xiao-bo; Yang, Pei-zhi

    2016-03-01

    The polycrystalline silicon thin films play an important role in the field of electronics. In the paper, α-SiAl composite membranes on glass substrates was prepared by magnetron co-sputtering. The contents of Al radicals encapsulated-in the α-Si film can be adjusted by changing the Al to Si sputtering power ratios. The as-prepared α-Si films were converted into polycrystalline films by using a rapid thermal annealing (RTP) at low temperature of 350 degrees C for 10 minutes in N2 atmosphere. An X-ray diffractometer, and Raman scattering and UV-Visible-NIR Spectrometers were used to characterize the properties of the Pc-Si films. The influences of Al content on the properties of the Pc-Si films were studied. The results showed that the polycrystalline silicon films were obtained from α-SiAl composite films which were prepared by magnetron co-sputtering at a low temperature following by a rapid thermal annealing. The grain size and the degree of crystallization of the Pc-Si films increased with the increase of Al content, while the optical band gap was reduced. The nc-Si films were prepared when the Al to Si sputtering power ratio was 0.1. And a higher Crystallization rate (≥ 85%) of polycrystalline silicon films were obtained when the ratio was 0.3. The band gaps of the polycrystalline silicon films can be controlled by changing the aluminum content in the films. PMID:27400496

  14. Comparative pharmacokinetic studies of fast dissolving film and oral solution of ondansetron in rats.

    PubMed

    Choudhary, Dhagla R; Patel, Vishnu A; Chhalotiya, Usmangani K; Patel, Harsha V; Kundawala, Aliasgar J

    2013-12-01

    Ondansetron, selective serotonin (5-HT3) receptor blocker, is used in treating chemotherapy induced nausea and vomiting in cancer patients. Mouth dissolving films containing ondansetron were developed to have better onset and patient compliances. The drug content of prepared films was within 85%-115%. The films were found to be stable for 4 months when stored at 40 %°C and 75% RH. In-vitro dissolution studies suggested a rapid disintegration, in which most of ondansetron was released (91.5±3.4%) within 90 sec. Subsequently, Sprague-Dawley rats were used to compare pharmacokinetic parameters of the formulated films with oral administration of pure drug solution. Pharmacokinetic parameters were similar between the two groups in which AUC0-t (ng h/ml), AUC0-∞ (ng h/ml), Cmax (ng/ml), Tmax (min), Kel (h(-1)) and t1/2 (h) of reference was 109.091±15.73, 130.32±18.56, 28.5±4.053, 60, 0.1860±0.0226, and 3.771±0.498 respectively; and for formulated film 113.663±16.64, 151.79±16.54, 30±3.51, 60, 0.1521±0.0310 and 4.755±0.653 respectively. These results suggest that the fast dissolving film containing ondansetron is likely to become one of the choices to treat chemotherapy induced nausea and vomiting. PMID:23755722

  15. Study of the growth of biaxially textured CeO2 films during ion-beam-assisted deposition

    NASA Astrophysics Data System (ADS)

    Kim, Chang Su; Jo, Sung Jin; Jeong, Soon Moon; Kim, Woo Jin; Baik, Hong Koo; Lee, Se Jong; Song, Kie Moon

    2005-03-01

    Biaxially textured CeO2 films were deposited on Hastelloy C276 substrates at room temperature using ion-beam-assisted e-beam evaporation with the ion beam directed at 55° to the normal of the film plane. The crystalline structure and in-plane orientation of films were investigated by x-ray diffraction 2θ-scan and phgr-scan. The orientation of the films was studied as a function of ion-to-atom ratio and film thickness. The ion-to-atom ratio was varied by independently adjusting the deposition rate and the ion current density. Under optimum condition, (200) textured CeO2 films have been successfully grown on Hastelloy C276.

  16. Study of high-temperature oxidation of ultrathin fe films on Pt(100) by using X-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Nahm, T.-U.

    2016-05-01

    High-temperature oxidation of iron thin films deposited on Pt(100) surfaces was studied by using X-ray photoelectron spectroscopy (XPS). Upon an oxygen exposure of 300 Langmuir onto a 7.5- monolayer (ML) Fe film at 830 K, about 2 monolayers of the Fe film were oxidized as Fe3O4 while the remaining Fe atoms diffused into the substrate. For 1.25-, 2.5-, and 3.75-monolayer Fe films, only about a monolayer of the Fe film was oxidized as FeO, regardless of the number of Fe atoms. The oxide layers on the 7.5-monolayer Fe film were observed to be stable upon post-annealing at 1030 K.

  17. Structural, morphology and electrical studies on ferroelectric bismuth titanate thin films prepared by sol?gel technique

    NASA Astrophysics Data System (ADS)

    Giridharan, N. V.; Madeswaran, S.; Jayavel, R.

    2002-04-01

    Crystal structure, surface morphology, compositional homogeneity and electrical properties of layered perovskite bismuth titanate (BTO) thin films have been investigated. BTO thin films were deposited on silicon and platinum-coated silicon substrates by spin coating. X-ray diffraction analysis confirms that the crystallinity of the films increases with increasing annealing temperature and the optimum temperature is found to be 600°C. Morphology studies by AFM showed that the surface of the films were smooth, dense and crack free. Composition analysis on the surface and in-depth confirms the stoichiometry of the films. C- V measurements show a counter-clockwise dielectric hysteresis, indicating that the ferroelectric property sufficiently controls the silicon potential with a memory width of 2 V. The leakage current density of the films is measured to be 2×10 -7 A/cm 2 from I- V characteristics at an applied voltage of 1 V.

  18. Study of thin TiC xN 1-x films fabricated by hybrid magnetron-laser deposition

    NASA Astrophysics Data System (ADS)

    Kocourek, Tomáš; Jelínek, Miroslav; Studnička, Václav; Kadlec, Jaromír

    2006-02-01

    Titanium- carbonitride thin films were grown at room temperature using a hybrid deposition arrangement combining DC magnetron sputtering and KrF pulsed laser deposition (MSPLD). Carbon and titanium were simultaneously deposited on the same Si substrate, dimensions of 3 cm × 3 cm. Films were fabricated in argon- nitrogen atmosphere of 1 Pa - 5 Pa, for laser fluence of 15 Jcm -2 and magnetron power of 150 W. Film properties were modified by RF discharge held between the target and substrate. Film crystallinity was studied by XRD and the composition depth profile of TiCN layers by glow discharge optical emission spectroscopy (GDOES).

  19. Study of cobalt mononitride thin films prepared using DC and high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gupta, Rachana; Pandey, Nidhi; Behera, Layanta; Gupta, Mukul

    2016-05-01

    In this work we studied cobalt mononitride (CoN) thin films deposited using dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS). A Co target was sputtered using pure N2 gas alone as the sputtering medium. Obtained long-range structural ordering was studies using x-ray diffraction (XRD), short-range structure using Co L2,3 and N K absorption edges using soft x-ray absorption spectroscopy (XAS) and the surface morphology using atomic force microscopy (AFM). It was found that HiPIMS deposited films have better long-range ordering, better stoichiometric ratio for mononitride composition and smoother texture as compared to dcMS deposited films. In addition, the thermal stability of HiPIMS deposited CoN film seems to be better. On the basis of different type of plasma conditions generated in HiPIMS and dcMS process, obtained results are presented and discussed.

  20. Studies on hard TaN thin film deposition by R C-Mag technique

    SciTech Connect

    Valleti, Krishna

    2009-07-15

    The physical and mechanical properties of pulsed rotating cylindrical magnetron sputter-grown tantalum nitride (TaN) thin films were studied. Initially, films were grown at ambient substrate temperature by varying the reactive (N{sub 2}) to sputter (Ar) gas ratio (R) at a constant pulsing frequency of the target power (100 kHz). The results were compared with planar magnetron-grown TaN samples. The R C-Mag. grown thin films have properties nearly similar to the high temperature (300 degree sign C) dc planar magnetron sputter deposited samples. In comparison to the planar magnetron deposition, the progression of the phase composition occurs over a wider range of R in the pulsed R C-Mag. deposition. These observed differences for R C-Mag. deposition are attributed to the increased glancing angle deposition of adatoms and pulsing of the target power. To study the effect of pulsing frequency of the target power in R C-Mag., the films were also grown at different frequencies at a fixed R (0.1). With the increase in frequency, the mechanical hardness increased up to 50 kHz and started decreasing beyond 50 kHz. The observed changes in the mechanical hardness are attributed to the increase in stress and to the formation of increased polycrystalline understoichiometric TaN phases.

  1. In situ study of self-assembled nanocomposite films by spectral SPR sensor.

    PubMed

    Zhang, Zhe; Liu, Jie; Qi, Zhi-mei; Lu, Dan-feng

    2015-06-01

    Spectral surface plasmon resonance (SPR) sensor with a time-resolved charge-coupled device (CCD) detector is a powerful analytical tool for label-free detection of biomolecular interaction at the liquid/solid interface and for in situ study of molecular adsorption behavior. In this work, the layer-by-layer self-assembly processes for three nanocomposite films were monitored in real time using a broadband spectral SPR sensor with a large dynamic range. Kinetics studies suggest that cytochrome c (Cyt c) and deoxy ribonucleic acid (DNA) adsorptions obey the Langmuir-isotherm theory, while gold nanoparticle (GNP) adsorption follows the Diffusion-controlled model. Using poly(sodium 4-styrenesulfonate) (PSS) and poly(dimethyldiallylammonium chloride) (PDDA) as the positively charged agents, three kinds of multilayer films such as the PSS/Cyt c, GNP/Cyt c and PDDA/DNA binary nanocomposites were fabricated on the SPR chips by the electrostatic attraction based on self-assemble. The SPR response in terms of ΔλR was measured to linear increase with increasing the number of layers for a six-bilayer PSS/Cyt c nanocomposite film, indicating that every PSS/Cyt c layer has equal mass coverage. In contrast, the nonlinear dependences of ΔλR on the number of bilayers were observed for the GNP/Cyt c and PDDA/DNA nanocomposite multilayer films. PMID:25842131

  2. Applications of Fourier Transform Raman spectroscopy to studies of thin polymer films

    SciTech Connect

    Zimba, C.G.; Hallmark, V.M.; Turrell, S.; Swalen, J.D.; Rabolt, J.F. )

    1990-01-25

    Raman spectroscopic studies of submicron-thick films have been accomplished through the use of integrated optical techniques. By using the film as an asymmetric slab waveguide for the laser excitation, and collecting the scattering emanating from the guided streak, the authors have obtained Raman spectra of organic films, polymer laminates, and molecular composites. The utility of the waveguide Raman spectroscopy technique has been limited by high levels of fluorescence when visible wavelength excitation is used. With the advent of FT-Raman spectroscopy, in which a near-infrared laser is used, Raman spectra of highly fluorescent and intensely colored materials could be easily obtained. In this study, waveguide Raman spectroscopic measurements using near-infrared excitation and a Michelson interferometer have been demonstrated. The use of a fiber optic bundle to collect the scattering and convert the image from a line to a circle has resulted in a 15-fold improvement over conventional lens collection. With the improved sensitivity, FT-Raman spectra of films containing small molecule chromophores imbedded in a polymer matrix have been obtained. In addition, extension of this method to polymers of low refractive index, by using a sublayer of very low refractive index material, such as MgF{sub 2}, has been outlined.

  3. MFM Study of Reversible and Irreversible Domain Wall Displacement in Thin Films.

    NASA Astrophysics Data System (ADS)

    Pokhil, Taras G.

    1996-03-01

    We have used the magnetic force microscope (MFM) to study the displacement of domain walls (DW) in thin amorphous TbFe films, prepared by RF sputtering and protected from oxidation by SiN over- and underlayers. In an external magnetic field, reversible bending of DW segments pinned to defects and irreversible jump-like displacement of DW segments were observed. The maximum observed length of curved segments of DW was about 150 nm. Measurement of the radius of curvature of DW segments bended in an external field allowed us to estimate the DW energy density and self-demagnetizing field of the film acting on DW. The DW energy density for these films was about 0.7 erg/square cm. Self-demagnetizing field for the film with saturation magnetization 100 G and thickness 80 nm, which exibited a maze-like domain structure, varied from 150 G to 400 G depending on the domain structure surrounding the studied DW segments. The irreversible displacement of DW was not a continuous process. The segments of DW 200-300 nm long move jump-like over a distance 100-150 nm.

  4. Application of micro-PIV to the study of staphylococci bacteria bio-film dynamics

    NASA Astrophysics Data System (ADS)

    Sherman, Erica; Bayles, Kenneth; Moormeier, Derek; Wei, Timothy

    2012-11-01

    Staphylococci bacteria are recognized as the most frequent cause of biofilm-associated infections. Although humans are regularly exposed to staphylococcus bacteria without consequence, a localized staph infection has the potential to enter the bloodstream and lead to serious infections such as endocarditis, pneumonia, or toxic shock syndrome. The mechanics of staphylococci biofilm formation and dispersion through the bloodstream are not well known. It has recently been observed that under certain flow conditions, bacteria grow in stable bio-films. Under other conditions, they organize in tower-like structures which break and are transported downstream by the flow. The fundamental questions addressed in this study are i) whether or not fluid mechanics plays a role in differentiating between film or tower formation and ii) whether or not the faulty towers are a bio-film propagation mechanism. This talk focuses on the application of micro-PIV to study this problem. Bacteria were cultured in a glass microchannel and subjected to a range of steady shear rates. Micro-PIV measurements were made to map the flow over and around different types of bio-film structures. Measurements and control volume analysis will be presented quantifying forces acting on these structures.

  5. Structural and ellipsometric study on tailored optical properties of tantalum oxynitride films deposited by reactive sputtering

    NASA Astrophysics Data System (ADS)

    Bousquet, Angélique; Zoubian, Fadi; Cellier, Joël; Taviot-Gueho, Christine; Sauvage, T.; Tomasella, Eric

    2014-11-01

    Oxynitride materials, which offer the possibility of merging oxide and nitride properties, are increasingly studied for this reason. This paper focuses on assessing the optical properties of tantalum oxynitride thin films deposited by pure tantalum target sputtering in an Ar/O2/N2 reactive atmosphere. First, by changing the oxygen to reactive gas flow rate ratio, and using thermal post-treatment, we deposited films with elemental compositions studied by Rutherford backscattering spectroscopy, ranging from a nitride (close to Ta3N5) to an oxide (close to Ta2O5) with various structures analyzed by x-ray diffraction. Their optical properties were investigated in depth by spectroscopic ellipsometry and UV-visible spectroscopy. For the ellipsometry investigation, we propose a model combining the Tauc-Lorentz law and additional Lorentz oscillator: the first contribution is linked to a semi-conductor or insulator film matrix, and the second one to the presence of conductive TaN crystals. Ellipsometry thus appears as a powerful tool to investigate complex materials such as tantalum oxynitrides. Moreover, we demonstrated that using this deposition method we were able to finely tune the film refractive index from 3.4 to 2.0 (at 1.96 eV) and the optical band gap, specifically from 1.3 to 2.7 eV.

  6. Methanol Diffusion into Thin Ionomer Films: An in situ Study Using Neutron Reflectometry .

    NASA Astrophysics Data System (ADS)

    He, Lilin

    2008-03-01

    THUSITHA, N. ETAMPAWALA DVORA, PERAHIA ^ Department of Chemistry, Clemson University, Clemson, SC 29634 JAROSLAW MAJEWSKI, Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, NM 87545 CHRISTOPHER J. CORNELIUS^ Sandia National Laboratories, MS 0886, Albuquerque, New Mexico 87185-0886 The penetration of solvent into a polymer that consists of incompatable groups is determined by the specific interactions with the guest molecule, where interfacial structure and dynamics of the polymer affect the onset of the process. The current work presents a neutron reflectometry study of the penetration of methanol into sulfonated polyphenlylene thin films. The ionomer films were exposed to saturated deuterated methanol vapor and reflectometry patterns were recorded until equilibrium was reached. The process incorporates two stages where the vapors first wet the surface and then penetrate into the film. Significant swelling takes place as soon as the film is exposed to the vapors. Similar to previous studied in water, the onset diffusion is Fickian followed by an anomalous diffusion process. The entire process however is faster than that observed for water.

  7. A Numerical Study of the Effect of Wake Passing on Turbine Blade Film Cooling

    NASA Technical Reports Server (NTRS)

    Heidmann, James D.

    1995-01-01

    Time-accurate and steady three-dimensional viscous turbulent numerical simulations were performed to study the effect of upstream blade wake passing unsteadiness on the performance of film cooling on a downstream axial turbine blade. The simulations modeled the blade as spanwise periodic and of infinite span. Both aerodynamic and heat transfer quantities were explored. A showerhead film cooling arrangement typical of modern gas turbine engines was employed. Showerhead cooling was studied because of its anticipated strong sensitivity to upstream flow fluctuations. The wake was modeled as a region of zero axial velocity on the upstream computational boundary which translated with each iteration. This model is compatible with a planned companion experiment in which the wakes will be produced by a rotating row of cylindrical rods upstream of an annular turbine cascade. It was determined that a steady solution with appropriate upstream swirl and stagnation pressure predicted the span-average film effectiveness quite well. The major difference is a 2 to 3 percent overprediction of span-average film effectiveness by the steady simulation on the pressure surface and in the showerhead region. Local overpredictions of up to 8 percent were observed in the showerhead region. These differences can be explained by the periodic relative lifting of the boundary layer and enhanced mixing in the unsteady simulations.

  8. In-situ Study of Nanostructure and Electrical Resistance of Nanocluster Films Irradiated with Ion Beams

    SciTech Connect

    Jiang, Weilin; Sundararajan, Jennifer A.; Varga, Tamas; Bowden, Mark E.; Qiang, You; McCloy, John S.; Henager, Charles H.; Montgomery, Robert O.

    2014-08-11

    An in-situ study is reported on the structural evolution in nanocluster films under He+ ion irradiation using an advanced helium ion microscope. The films consist of loosely interconnected nanoclusters of magnetite or iron-magnetite (Fe-Fe3O4) core-shells. The nanostructure is observed to undergo dramatic changes under ion-beam irradiation, featuring grain growth, phase transition, particle aggregation, and formation of nanowire-like network and nano-pores. Studies based on ion irradiation, thermal annealing and election irradiation have indicated that the major structural evolution is activated by elastic nuclear collisions, while both electronic and thermal processes can play a significant role once the evolution starts. The electrical resistance of the Fe-Fe3O4 films measured in situ exhibits a super-exponential decay with dose. The behavior suggests that the nanocluster films possess an intrinsic merit for development of an advanced online monitor for neutron radiation with both high detection sensitivity and long-term applicability, which can enhance safety measures in many nuclear operations.

  9. Structural and optical studies on Nd doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Deepa Rani, T.; Tamilarasan, K.; Elangovan, E.; Leela, S.; Ramamurthi, K.; Thangaraj, K.; Himcinschi, C.; Trenkmann, I.; SchuIze, S.; Hietschold, M.; Liebig, A.; Salvan, G.; Zahn, D. R. T.

    2015-01-01

    Thin films of Zn1-xNdxO were deposited by spray pyrolysis on Si(111) substrates preheated at 400 °C temperature and were studied as a function of neodymium (Nd)-doping concentration. X-ray diffraction (XRD) patterns confirmed that the deposited films possess hexagonal wurtzite ZnO structure. Further, it is observed that the doped films show a preferential orientation along the c-axis (0 0 2), which is perpendicular to the substrate. The un-doped films seem to be having a bit low-crystallinity, which is corroborated by the scanning electron microscope (SEM) analysis that showed nano-crystalline like features. Further, SEM analysis showed that the Nd doping triggers the formation bubble-like structure on top of the nano-crystalline structure. The SEM microstructures are interpreted with the Micro-Raman studies. Photoluminescence (PL) and XRD characterizations indicate that above 5 at.% doping concentrations, the Nd atoms preferentially agglomerate in the large islands.

  10. Studies of two dimensional superconductor-normal metal hybrid thin films

    NASA Astrophysics Data System (ADS)

    Long, Zhenyi

    2005-11-01

    It has been predicted that simple metallic phase do NOT exist in two-dimensional electronic systems. Disorder that exists in two dimensions, no matter how small, can localize the electrons. Therefore, two-dimensional electronic systems could assume either a superconducting state or an insulating state. However, our studies have revealed an exotic two-dimensional electronic system that exhibits a combination of characters of a superconductor and a normal metal. These investigations have shed a light on a novel approach for the Superconductor-Normal Metal transition in two dimensions. The model systems we studied are hybrid superconductor (Pb)-normal metal (Ag) thin films, fabricated by quench condensation onto extremely cold substrates (TS ≅ 8 K). We have performed transport and tunneling spectroscopy measurements (down to 60 milli-Kelvin) to investigate the novel superconducting properties of the thin films. We have also utilized in situ STM to directly characterize the morphology of the hybrid thin films. With Pb thickness fixed, increasing Ag thickness drives down the superconducting transition temperature and energy gap in density of states of the hybrid films. Simultaneously, as Ag thickness increases, a linear DOS in the subgap region grows from the Fermi energy. According to quasiclassical theories, this subgap DOS implies that quasiparticles are localized in the normal metal for long enough time so that they become decoupled form the superconductor. The growth in the subgap DOS gives the DOS a hybrid metal-superconductor appearance that might signal a novel superconductor to metal transition in two dimensions.

  11. Phase-field model for compositional and morphological evolution studies in thin film heteroepitaxial systems

    NASA Astrophysics Data System (ADS)

    Singh, Nitin

    , which are solved using a nonlinear multigrid method. The model is used to investigate the influence of the sign of compositional strain and of the epitaxial mismatch on the arrangement of the equilibrium phases within the film. These studies indicate the possibility of compositional self-assembly processes in addition to morphological self-assembly.

  12. Magnetization studies of first-order magnetostructural phase transition in polycrystalline FeRh thin films

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Huang, Ping; Chen, Zhe; He, Chenchong; Wang, Yuxin; Yan, Biao

    2012-10-01

    The nucleation and growth of the transformed phase in the matrix of the original phase played an important role in the progress of magnetic transition. In spite of extensive investigations in B2 ordered FeRh alloy systems, until now few studies have been conducted for clarifying the nucleation and growth mechanism of the antiferromagnetic-ferromagnetic phase transition in FeRh alloys. In this work, B2 ordered polycrystalline FeRh thin films were fabricated on glass substrates by a sputtering technique and subsequent heat treatment. The as-deposited film shows a nonmagnetic property because of its face centred cubic structure. After annealing, the polycrystalline FeRh thin films show a clear first-order magnetostructural phase transition. The FeRh thin film shows an overall activation energy of about 228.6 kJ mol-1 for the entire first-order magnetostructural phase transition process. Results suggest that the first-order magnetostructural phase transition in ordered FeRh thin films follows the Johnson-Mehl-Avrami model with characteristic exponent n in the range 1-4, indicating that the phase transition process is a multi-step process characterized by different nucleation and growth mechanisms of the new ferromagnetic phase. The results obtained in this study will shed light on the underlying physics of the first-order magnetostructural phase transition of ordered FeRh alloys. The applicability of the concepts used in this study to the FeRh system shows universality and can be applied to other material systems where there is a first-order magnetostructural phase transition such as in manganites.

  13. Reel Science: An Ethnographic Study of Girls' Science Identity Development In and Through Film

    NASA Astrophysics Data System (ADS)

    Chaffee, Rachel L.

    This dissertation study contributes to the research on filmmaking and identity development by exploring the ways that film production provided unique opportunities for a team of four girls to engage in science, to develop identities in science, and to see and understand science differently. Using social practice, identity, and feminist theory and New Literacies Studies as a theoretical lens and grounded theory and multimodality as analytic frameworks, I present findings that suggest that girls in this study authored identities and communicated and represented science in and through film in ways that drew on their social, cultural, and embodied resources and the material resources of the after-school science club. Findings from this study highlight the affordances of filmmaking as a venue for engaging in the disciplinary practices of science and for accessing and authoring identities in science.

  14. Comparative Study Of Image Enhancement Algorithms For Digital And Film Mammography

    SciTech Connect

    Delgado-Gonzalez, A.

    2008-08-11

    Here we discuss the application of edge enhancement algorithms on images obtained with a Mammography System which has a Selenium Detector and on the other hand, on images obtained from digitized film mammography. Comparative analysis of such images includes the study of technical aspects of image acquisition, storage, compression and display. A protocol for a local database has been created as a result of this study.

  15. Toward Autonomy in Love and Work: Situating the Film "Yo, tambien" within the Political Project of Disability Studies

    ERIC Educational Resources Information Center

    Fraser, Benjamin

    2011-01-01

    This essay looks at the representation of disability in the recent Spanish film "Yo, tambien" through the lens of disability studies, understood as a political project. The film's portrayal of a character who is, like the actor who plays him, Europe's first university graduate with Down syndrome, is unique. Moreover, "Yo, tambien" provides the…

  16. Studies on Various Functional Properties of Titania Thin Film Developed on Glazed Ceramic Wall Tiles

    NASA Astrophysics Data System (ADS)

    Anil, Asha; Darshana R, Bangoria; Misra, S. N.

    A sol-gel based TiO2 thin film was applied on glazed wall tiles for studying its various functional properties. Thin film was deposited by spin coating on the substrate and subjected to curing at different temperatures such as 600°C, 650, 700°C, 750°C and 800°C with 10 minutes soaking. The gel powder was characterized by FTIR, DTA/TG and XRD. Microstructure of thin film was analyzed by FESEM and EDX. Surface properties of the coatings such as gloss, colour difference, stain resistance, mineral hardness and wettability were extensively studied. The antibacterial activity of the surface of coated substrate against E. coli was also examined. The durability of the coated substrate in comparison to the uncoated was tested against alkali in accordance with ISO: 10545 (Part 13):1995 standard. FESEM images showed that thin films are dense and homogeneous. Coated substrates after firing results in lustre with high gloss, which increased from 330 to 420 GU as the curing temperature increases compared to that of uncoated one (72 GU). Coated substrate cured at 800°C shows higher mineral hardness (5 Mohs’) compared to uncoated one (4 Mohs’) and films cured at all temperatures showed stain resistance. The experimental results showed that the resistance towards alkali attack increase with increase in curing temperature and alkali resistance of sample cured at 800 °C was found to be superior compared to uncoated substrate. Contact angle of water on coated surface of substrates decreased with increase in temperature. Bacterial reduction percentages of the coated surface was 97% for sample cured at 700°C and it decreased from 97% to 87% as the curing temperature increased to 800 °C when treated with E. coli bacteria.

  17. Growth of a Pt film on non-reduced ceria: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Loffreda, David; Delbecq, Françoise

    2012-01-01

    The growth of platinum on non-reduced CeO2 (111) surface is studied by means of calculations based on the density functional theory. Particles of increasing size are formed on the oxide surface by incorporating the platinum atoms one by one until multilayer films are obtained. The main conclusion is that platinum atoms tend to maximize the number of metallic bonds and to approach the situation of the bulk, hence preferring films to particles, particles to isolated atoms, and a three-dimensional growth to a two-dimensional one. The supported particles and the films exhibit a contraction of the Pt-Pt distances, with respect to those of the Pt bulk, in order to match the ceria lattice. The density of states projected on the film surface platinum atoms shows important differences in shape and energy (lower d-band center) compared to the Pt(111) reference surface, which could be the major reason for the observed changes in catalytic reactivity when deposited particles are compared with single crystal surfaces.

  18. Ellipsometric study of oxide films formed on LDEF metal samples. Final report

    SciTech Connect

    Franzen, W.; Brodkin, J.S.; Sengupta, L.C.; Sagalyn, P.L.

    1992-02-01

    The optical constants of samples of six different metals (Al, Cu, Ni, Ta, W, and Zr) exposed to space on the long duration exposure facility (LDEF) have been studied by variable angle spectroscopic ellipsometry. Measurements were also carried out on portions of each sample which were shielded from direct exposure by a metal bar. A least-squares fit of the data using an effective medium approximation was then carried out with thickness and composition of surface films formed on the metal substrates as variable parameters. The analysis revealed that exposed portions of the Cu, N Ta, and Zr samples are covered with porous oxide films ranging in thickness from 500 to 1000. The 410 A thick film Of Al203 on the exposed Al sample is practically free of voids. Except for Cu, the shielded portions of these metals are covered by thin nonporous oxide films characteristic of exposure to air. The shielded part of the Cu sample has a much thicker porous coating of Cu2O. The tungsten data could not be analyzed.

  19. Studying gas-sheared liquid film in horizontal rectangular duct with laser-induced fluorescence technique

    NASA Astrophysics Data System (ADS)

    Cherdantsev, Andrey; Hann, David; Azzopardi, Barry

    2013-11-01

    High-speed LIF-technique is applied to study gas-sheared liquid film in horizontal rectangular duct with 161 mm width. Instantaneous distributions of film thickness resolved in both longitudinal and transverse coordinates were obtained with a frequency of 10 kHz and spatial resolution from 0.125 mm to 0.04 mm. Processes of generation of fast and slow ripples by disturbance waves are the same as described in literature for downwards annular pipe flow. Disturbance waves are often localized by transverse coordinate and may have curved or slanted fronts. Fast ripples, covering disturbance waves, are typically horseshoe-shaped and placed in staggered order. Their characteristic transverse size is of order 1 cm and it decreases with gas velocity. Entrainment of liquid from film surface can also be visualized. Mechanisms of ripple disruption, known as ``bag break-up'' and ``ligament break-up,'' were observed. Both mechanisms may occur on the same disturbance waves. Various scenarios of droplet deposition on the liquid film are observed, including the impact, slow sinking and bouncing, characterized by different outcome of secondary droplets or entrapped bubbles. Number and size of bubbles increase greatly inside the disturbance waves. Both quantities increase with gas and liquid flow rates. EPSRC Programme Grant MEMPHIS (EP/K003976/1), and Roll-Royce UTC (Nottingham, for access to flow facility).

  20. Temperature effect on low-k dielectric thin films studied by ERDA

    SciTech Connect

    Jensen, Jens; Possnert, Göran; Zhang, Yanwen

    2008-09-23

    Low-k dielectric materials are becoming increasingly interesting as alternative to SiO2 with device geometries shrinking beyond the 65 nm technology node. At elevated temperatures hydrogen migration becomes an important degradation mechanism for conductivity breakdown in semiconductor devices. The possibility of hydrogen release during the fabrication process is, therefore, of great interest in the understanding of device reliability. In this study, various low-k dielectric films were subjected to thermal annealing at temperatures that are generally used for device fabrication. Elastic recoil detection analysis (ERDA) was used to investigate compositional changes and hydrogen redistribution in thin films of plasma-enhanced tetraethylortho-silicate (PETEOS), phosphorus doped silicon glass (PSG), silicon nitride (SiN) and silicon oxynitride (SiON). Except for an initial hydrogen release from the surface region in films of PETEOS and PSG, the results indicate that the elemental composition of the films was stable for at least 2 hours at 450°C.

  1. A study on properties of PLA/PBAT from blown film process

    NASA Astrophysics Data System (ADS)

    Hongdilokkul, P.; Keeratipinit, K.; Chawthai, S.; Hararak, B.; Seadan, M.; Suttiruengwong, S.

    2015-07-01

    The aim of this work was to study the properties of films based on PLA/PBAT blend prepared by the reactive compounding. PLA/PBAT blends were prepared at the weight ratio of 80:20 together with peroxide as a reactive agent in a twin screw extruder with temperature profile of 160/170/180/210/220/190/175/150°C from feed to die zone. All blended samples, neat PLA, and neat PBAT were characterized for morphology, mechanical and rheological properties. SEM micrographs showed finely dispersed phases of PBAT in PLA in all cases. The particle sizes of PBAT were around 1 μm. The results indicated that the drawability and toughness properties of PLA were greatly improved when blended with 20%wt PBAT. The interface adhesion, and mechanical properties of PLA/PBAT blends were also improved when adding a very small quantity of peroxide. PLA/PBAT blends were then used to produce films. The film characteristics and mechanical properties were examined. Tensile strength of films was significantly improved in the machine direction in PLA/PBAT/peroxide blends whereas the good optical transparent property were remained the same compared with neat PLA.

  2. Theoretical and experimental study of the porous film using quartz crystal microbalance.

    PubMed

    Zhang, Songpeng; Zhang, Xiangjun; Tian, Yu; Meng, Yonggang

    2016-03-01

    The self-assembled multilayers have been studied by many researchers to modify the surfaces of artificial implants for increasing biocompatibility. The accurate mechanical properties of the film can only be obtained from the experimental results using appropriate theoretical models. As the film is composed of both solid polymers and fluid, this paper proposes a two-phase model. Based on the volume average method, the momentum equations are derived for both solid and liquid phases. In order to test our model, we built the porous film on the gold chip of the quartz crystal microbalance using the layer-by-layer method. The buildup process is based on the electrostatic interactions between anionic sodium hyaluronate and cationic chitosan by imitating the endothelial surface layer. By fitting our model to the experimental changes of the resonant frequency and dissipation factor, we get reasonable values of the film thickness, the porosity, the shear modulus of the solid phase, and the permeability. Compared with the existing models, the newly introduced permeability is an important property of the porous layer affecting the values of other parameters. Our model can provide more intrinsic properties of the self-assembled polymeric network and explain its interaction with the permeating fluid. PMID:27190562

  3. A study of electronic shorting in IBDA-deposited Lipon films

    NASA Astrophysics Data System (ADS)

    Vereda, F.; Clay, N.; Gerouki, A.; Goldner, R. B.; Haas, T.; Zerigian, P.

    Because a near term goal of our research is to obtain optimal performance LiCoO 2/lithium phosphorus oxynitride (Lipon)/C thin film batteries, and due to the major importance of the electrolyte in any battery, we have recently been attempting to better understand the causes of electronic shorting in our Lipon electrolyte films. After studying the residual and temperature-dependent stress of these films and observing cracking after they had undergone a temperature change from 300°C to room temperature, we adopted a model in which the thermal expansion coefficient mismatch between Lipon and our glass substrates accounted for the cracking and therefore led to the shorting. This model was also supported by evidence that Al films (which had thermal expansion coefficients close to that of Lipon and proved to act as "buffer layers" by preventing cracking of Lipon when glass/Al/Lipon structures were cooled from 300°C to room temperature) were successfully used to produce short-free Al/Lipon/Al devices.

  4. Structural, electrical and optical studies of SILAR deposited cadmium oxide thin films: Annealing effect

    SciTech Connect

    Salunkhe, R.R.; Dhawale, D.S.; Gujar, T.P.; Lokhande, C.D.

    2009-02-04

    Successive ionic layer adsorption and reaction (SILAR) method has been successfully employed for the deposition of cadmium oxide (CdO) thin films. The films were annealed at 623 K for 2 h in an air and changes in the structural, electrical and optical properties were studied. From the X-ray diffraction patterns, it was found that after annealing, H{sub 2}O vapors from as-deposited Cd(O{sub 2}){sub 0.88}(OH){sub 0.24} were removed and pure cubic cadmium oxide was obtained. The as-deposited film consists of nanocrystalline grains of average diameter about 20-30 nm with uniform coverage of the substrate surface, whereas for the annealed film randomly oriented morphology with slight increase in the crystallite size has been observed. The electrical resistivity showed the semiconducting nature with room temperature electrical resistivity decreased from 10{sup -2} to 10{sup -3} {omega} cm after annealing. The decrease in the band gap energy from 3.3 to 2.7 eV was observed after the annealing.

  5. In situ oxidation studies on /001/ copper-nickel alloy thin films

    NASA Technical Reports Server (NTRS)

    Heinemann, K.; Rao, D. B.; Douglass, D. L.

    1977-01-01

    High-resolution transmission electron microscopy studies are reported of (001)-oriented single crystalline thin films of Cu-3%Ni, Cu-4.6%Ni, and Cu-50%Ni alloy which were prepared by vapor deposition onto (001) NaCl substrates and subsequently annealed at around 1100 K and oxidized at 725 K at low oxygen partial pressure. At all alloy concentrations, Cu2O and NiO nucleated and grew independently without the formation of mixed oxides. The shape and growth rates of Cu2O nuclei were similar to rates found earlier. For low-nickel alloy concentrations, the NiO nuclei were larger and the number density of NiO was less than that of Cu-50%Ni films for which the shape and growth rates of NiO were identical to those for pure nickel films. Phenomena involving a reduced induction period, surface precipitation, and through-thickness growth are also described. The results are consistent with previously established oxidation mechanisms for pure copper and pure nickel films.

  6. SPM Study and Growth Mechanism of Graphene Directly CVD-Grown on h-BN Film

    NASA Astrophysics Data System (ADS)

    Song, Young Jae; Kim, Minwoo; Wu, Qinke; Lee, Joohyun; Lee, Sungjoo; Wang, Min

    2014-03-01

    We present our Scanning Tunneling Microscopy (STM)/Spectroscopy (STS) and Kelvin Probe Force Microscope (KPFM) study for graphene directly CVD-grown on h-BN film. High resolution STM image shows perfect honeycomb lattice structure of graphene on top surface and Moiré pattern indicating the structural interference patter with the underlying h-BN crystal. Non-disturbed electronic structure of graphene on h-BN film is also confirmed by spatially-resolved STS measurements, which show very sharp and symmetric V shape with a Dirac point at Fermi level. To confirm the graphene growth mechanism on h-BN film/Cu foil, careful Atomic Force Microscopy (AFM) and Kelvin Probe Force Microscopy (KPFM) measurements were performed on different thickness of h-BN film on a SiO2 substrate to unveil the catalytic origin of graphene growth on h-BN/Cu. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Korean government (MSIP) (Grant Numbers: 2009-0083540, 2011-0030046, 2012R1A1A2020089 and 2012R1A1A1041416).

  7. Adsorption of quantum dots onto polymer and Gemini surfactant films: a quartz crystal microbalance study.

    PubMed

    Alejo, T; Merchán, M D; Velázquez, M M

    2014-08-26

    We used quartz crystal microbalance with dissipation to study the mechanical properties, the kinetics of adsorption, and the amount of CdSe quantum dots (QDs) adsorbed onto a SiO2 sensor, referred as bare sensor, onto the sensor modified with a film of the polymer poly(maleic anhydride-alt-1-octadecene), PMAO, or with a film of the Gemini surfactant ethyl-bis(dimethyl octadecyl ammonium bromide), abbreviated as 18-2-18. Results showed that when the sensor is coated with polymer or surfactant molecules, the coverage increases compared with that obtained for the bare sensor. On the other hand, rheological properties and kinetics of adsorption of QDs are driven by QD nanoparticles. Thus, the QD films present elastic behavior, and the elasticity values are independent of the molecule used as coating and similar to the elasticity value obtained for QDs films on the bare sensor. The QD adsorption is a two-step mechanism in which the fastest process is attributed to the QD adsorption onto the solid substrate and the slowest one is ascribed to rearrangement movements of the nanoparticles adsorbed at the surface. PMID:25093530

  8. Cathodoluminescence studies of C{sub 60} fullerene-based films and nanostructures

    SciTech Connect

    Nashchekin, A. V. Baryshev, S. V.; Sokolov, R. V.; Usov, O. A.

    2007-08-15

    The objects of investigation in this work are submicron Cm fullerene-based films and fullerene nanostructures fabricated by electron-beam lithography. The set of techniques for studying the fullerenes is extended due to attraction of the spectral cathodoluminescence (CL) to either of the initial fullerene films or submicron net structures with period of about 0.9 {mu}m, wall height 0.6 {mu}m, and width about 0.4 {mu}m.The maxima of the CL spectra of the initial C{sub 60} films are in good agreement with the energy-band structure of the amorphous fullerene film. In turn, the CL spectrum of the fullerene net structures possesses both peculiarities of the fullerene energy-band structure and it clearly exhibits the oscillations of the spectrum with a period as large as 0.08 eV. Such periodical fullerence net structures possess the properties of an optical resonator on the system 'fullerene net (n = 2.3)-air (n = 1).'.

  9. Photoluminescence, ellipsometric, optical and morphological studies of sprayed Co-doped ZnO films

    NASA Astrophysics Data System (ADS)

    Gençyılmaz, O.; Atay, F.; Akyüz, I.

    2016-06-01

    In this study, undoped and cobalt (Co)-doped zinc oxide (ZnO) films were successfully produced by ultrasonic spray pyrolysis (USP) technique at low temperature (350°C). The optical and surface properties were investigated as a function of Co content. The optical parameters (thickness, refractive index and extinction coefficient) were determined using spectroscopic ellipsometry (SE) and it was seen that the refractive index and extinction coefficient values of Co-doped ZnO films decreased slightly depending on the increasing of Co doping. For investigation, the transmittance and photoluminescence (PL) spectra of the films, UV-Vis spectrophotometer and PL spectroscopy were used at room temperature. The transmittance spectra show that transmittance values decreased and Co+2 ions substitute Zn+2 ions of ZnO lattice. The optical band gap values decreased from 3.26 eV to 2.85 eV with the changing of Co content. The results of PL spectra exhibit the position of the different emission peaks unchanged but the intensity of peaks increased with increasing Co doping. Also, the surface properties of the films were obtained by atomic force microscopy (AFM) and these results indicated that the surface morphology and roughness values were prominently changed with Co doping.

  10. Spectroscopic study of the highly homogeneous polyaniline film formation on gold support

    NASA Astrophysics Data System (ADS)

    Morávková, Zuzana; Stejskal, Jaroslav; Trchová, Miroslava

    2016-01-01

    The oxidation of aniline with ammonium peroxydisulfate in the aqueous solution of acetic acid has two subsequent phases: the oxidation of the neutral aniline molecules at low acidity, which was followed by the oxidation of the anilinium cations after the acidity became higher. The final polyaniline film deposited on immersed surfaces is usually contaminated with semi-crystalline oligomers which precipitated during induction period from the reaction medium. To obtain a homogeneous film, which is important in the fabrication of many molecular electronic devices, we have studied the course of aniline oxidation in a view of new experimental evidence. In the unique series of experiments, the silicon or gold supports have been immersed in the reaction mixture at crucial stages of oxidation reaction, and the deposits at the end of the reaction were analyzed. The growth of a highly homogenous film on the gold-coated glass substrate immersed in the reaction mixture at the end of the polymerization period has been observed. The molecular structure of the products was monitored with UV-visible, infrared, and Raman spectroscopies. The possible mechanism of the film formation and the molecular mechanism of the surface interaction of chemisorbed aniline oligomers with gold support are proposed.

  11. Spectroscopic study of the highly homogeneous polyaniline film formation on gold support.

    PubMed

    Morávková, Zuzana; Stejskal, Jaroslav; Trchová, Miroslava

    2016-01-01

    The oxidation of aniline with ammonium peroxydisulfate in the aqueous solution of acetic acid has two subsequent phases: the oxidation of the neutral aniline molecules at low acidity, which was followed by the oxidation of the anilinium cations after the acidity became higher. The final polyaniline film deposited on immersed surfaces is usually contaminated with semi-crystalline oligomers which precipitated during induction period from the reaction medium. To obtain a homogeneous film, which is important in the fabrication of many molecular electronic devices, we have studied the course of aniline oxidation in a view of new experimental evidence. In the unique series of experiments, the silicon or gold supports have been immersed in the reaction mixture at crucial stages of oxidation reaction, and the deposits at the end of the reaction were analyzed. The growth of a highly homogenous film on the gold-coated glass substrate immersed in the reaction mixture at the end of the polymerization period has been observed. The molecular structure of the products was monitored with UV-visible, infrared, and Raman spectroscopies. The possible mechanism of the film formation and the molecular mechanism of the surface interaction of chemisorbed aniline oligomers with gold support are proposed. PMID:26231780

  12. Optical study of strained ultrathin films of strongly correlated LaNiO3

    SciTech Connect

    Stewart, M.K.; Yee, C.H.; Kareev, M; Smith, R.K.; Chapler, B.C.; Varela del Arco, Maria; Ryan, P.J.; Haule, K.; Chakalian, J.; Basov, D. N.

    2011-01-01

    An optical study of fully strained ultrathin LaNiO{sub 3} films is presented and compared with LDA + DMFT calculations. LaNiO{sub 3} films were grown by pulsed laser deposition on LaAlO{sub 3} and SrTiO{sub 3} substrates which provide compressive and tensile strain, respectively. Optical conductivity data show a Drude peak with a spectral weight that is significantly reduced compared to that obtained from LDA calculations. The extended Drude analysis reveals the presence of a pseudogap around 80 meV for the film on SrTiO{sub 3} and near 40 meV, at low temperature only, for the film on LAO. An unusual temperature dependence of the optical conductivity is observed, with the Drude plasma frequency increasing by up to 20% at low temperature due to spectral weight transfer from bands lying 2-4 eV below the Fermi energy. Such a strong temperature dependence of the Drude spectral weight has previously been reported for correlated electron systems in which a phase transition is present. In LaNiO{sub 3}, however, no phase transition is observed.

  13. Study of photon–magnon coupling in a YIG-film split-ring resonant system

    SciTech Connect

    Bhoi, B.; Aiyar, R.; Cliff, T.; Maksymov, I. S.; Kostylev, M.; Venkataramani, N.; Prasad, S.; Stamps, R. L.

    2014-12-28

    By using the stripline Microwave Vector–Network Analyser Ferromagnetic Resonance and Time Domain spectroscopy techniques, we study a strong coupling regime of magnons to microwave photons in the planar geometry of a lithographically formed split-ring resonator (SRR) loaded by a single-crystal epitaxial yttrium–iron–garnet (YIG) film. Strong anti-crossing of the photon modes of SRR and of the magnon modes of the YIG film is observed in the applied-magnetic-field resolved measurements. The coupling strength extracted from the experimental data reaches 9% at 3 GHz. Theoretically, we propose an equivalent circuit model of the SRR loaded by a magnetic film. This model follows from the results of our numerical simulations of the microwave field structure of the SRR and of the magnetisation dynamics in the YIG film driven by the microwave currents in the SRR. The results obtained with the equivalent-circuit model are in good agreement with the experiment. This model provides a simple physical explanation of the process of mode anti-crossing. Our findings are important for future applications in microwave quantum photonic devices as well as in nonlinear and magnetically tuneable metamaterials exploiting the strong coupling of magnons to microwave photons.

  14. Study on laser damage of high transmission single layer optical thin film for fused silica glass induced by inclusion

    NASA Astrophysics Data System (ADS)

    Hao, Ming-ming; Lu, Guo-guang; Zhu, Hong-bo; Wang, Li-na

    2015-08-01

    In order to research the laser damage mechanism of high transmission single layer optical thin film for fused silica glass, finite element method was used to calculate laser induced damage threshold (LIDT) and an optical test system with a nanosecond solid-state lasers was set up to determine the LIDT according to standard of ISO 11254. Firstly, finite element model was created at COMSOL multi-physics software and the temperature of inclusion in the optical thin film was calculated with different physical parameter. It is found that temperature at center of the inclusion firstly decreases and then increase with the increasing of inclusion depth. It is also found that the temperature constantly increase with the radius increasing from 20nm to 100nm. Moreover, the inclusion temperature for MgF2 thin film is higher than that of CaF2 thin film. Lastly, LIDT were measured by the optical test system, and the average value of LIDT is 3.7J/cm2 for MgF2 thin film and 4.6J/cm2 for CaF2 thin film, which is well fit with the value calculated by COMSOL software. The study shows that finite element method is an effective method to calculate LIDT for optical thin film and impurity has significant impact on the LIDT of optical thin film and therefore decreasing the density of the impurity would increase the LIDT of the thin film.

  15. Continuum studies of microstructure formation in metallic and organic thin films

    NASA Astrophysics Data System (ADS)

    Muralidharan, Srevatsan

    In this dissertation, microstructure formation processes in binary metallic ultra-thin films and organic polycrystalline thin films are studied through a combination of theoretical model development, analysis, and numerical simulations. In binary metallic films, to investigate compositional patterning and misfit dislocation formation, a quantitative approach based on the so called phase-field crystal method is developed. Both through analysis and simulations of the model, a number of generic and limiting cases of surface alloy epitaxial systems are investigated to examine the effects of lattice mismatch, adlayer-substrate interaction potential, and line tension on equilibrium compositional domain size. A procedure is developed to quantitatively relate the parameters of the model to a specific system [CoAg/Ru(0001)], and it is demonstrated that simulations capture experimentally observed morphologies. Then, the model is employed to investigate the effects of misfit strain fields in the substrate on both heterogeneous nucleation behavior and anisotropic growth of islands at submonolayer coverages and compositional patterning at complete monolayer coverage via simulations. In particular, in the case of binary systems at complete monolayer coverage, strain-stabilized compositional domains emerge at low line tension values for both substrates. Interestingly, the compositional domains on the QC substrate inherit their symmetries at sufficiently low line tension values, while at larger line tension values, the domain structure begins to resemble the classical spinodal microstructure. These studies will enable physically-based design of nanoscale features for a broad range of applications, such as catalysis. In organic polycrystalline films, our focus is on determining the effects of additives and substrate templating on nucleation and grain growth behavior of solution processed triethylsilylethynyl anthradithiophene films. Through a mean-field approach, it is demonstrated

  16. Studies of the thermal stability and crystallization behavior of electroless and evaporated nickel and cobalt alloy films

    NASA Astrophysics Data System (ADS)

    Antonelli, Sarah Bowen

    Electroless Ni and Co alloy films are currently being studied for the purpose of replacing dielectric materials as Cu diffusion barriers in microelectronic devices. Electroless films offer the advantages of selectivity, conformality, reduced Cu electromigration, and reduced cost. Amorphous films are preferred, to eliminate grain boundaries, which are fast diffusion paths. It is desirable for these films to remain amorphous up to ˜700°C to be able to maintain their barrier properties throughout the fabrication process. Previously studied films include various Ni and Co alloys containing dopants such as P, B, W, Mo, and Re, which are added to inhibit nucleation. These films have limited thermal stability and do not maintain their barrier properties above 500°C. The studies presented here focus on understanding the roles of the different types of dopants in suppressing nucleation of the electroless films to be able to design a new film that remains amorphous at higher temperatures. Ni-P films were studied for the purpose of developing an atomic level model of the nucleation process and how the P inhibits f.c.c. Ni nucleation. Ni-W-P and Ni-P films with the same amount of P were compared to determine the impact of added W. Results show that W suppresses Ni3P and not Ni formation. This result suggests that to suppress Ni nucleation, W (and other similar atoms such as Mo and Re) should be replaced with an atom that has limited mutual solubility with Ni and a deep eutectic in its phase diagram with Ni, for example Ce. To test this hypothesis, Ni-B-Ce and Ni-B-Mo films, with ˜20 atom % B and ˜6-7 atom % Ce or Mo, were compared. Both remained amorphous up to 600°C because Ce and Mo suppress Ni3B nucleation while B suppresses Ni nucleation. Ni-Ce and Ni-Mo films, with ˜6-7 atom % Ce or Mo, contain Ni as deposited, but the Ni-Ce film has smaller crystallites. The Ni-Ce film with ˜12-13 atom % Ce is amorphous as deposited, while the analogous Ni-Mo film contains

  17. Theoretical and material studies on thin-film electroluminescent devices

    NASA Technical Reports Server (NTRS)

    Summers, C. J.; Goldman, J. A.; Brennan, K.

    1988-01-01

    During this report period work was performed on the modeling of High Field Electronic Transport in Bulk ZnS and ZnSe, and also on the surface cleaning of Si for MBE growth. Some MBE growth runs have also been performed in the Varian GEN II System. A brief outline of the experimental work is given. A complete summary will be done at the end of the next reporting period at the completion of the investigation. The theoretical studies are included.

  18. Theoretical and material studies on thin-film electroluminescent devices

    NASA Technical Reports Server (NTRS)

    Summers, C. J.; Brennan, K. F.

    1986-01-01

    Electroluminescent materials and device technology were assessed. The evaluation strongly suggests the need for a comprehensive theoretical and experimental study of both materials and device structures, particularly in the following areas: carrier generation and multiplication; radiative and nonradiative processes of luminescent centers; device modeling; new device concepts; and single crystal materials growth and characterization. Modeling of transport properties of hot electrons in ZnSe and the generation of device concepts were initiated.

  19. Theoretical and experimental study of inverted annular film boiling and regime transition during reflood transients

    NASA Astrophysics Data System (ADS)

    Mohanta, Lokanath

    The Loss of Coolant Accident (LOCA) is a design basis accident for light water reactors that usually determines the limits on core power. During a LOCA, film boiling is the dominant mode of heat transfer prior to the quenching of the fuel rods. The study of film boiling is important because this mode of heat transfer determines if the core can be safely cooled. One important film boiling regime is the so-called Inverted Annular Film Boiling (IAFB) regime which is characterized by a liquid core downstream of the quench front enveloped by a vapor film separating it from the fuel rod. Much research have been conducted for IAFB, but these studies have been limited to steady state experiments in single tubes. In the present work, subcooled and saturated IAFB are investigated using high temperature reflood data from the experiments carried out in the Rod Bundle Heat Transfer (RBHT) test facility. Parametric effects of system parameters including the pressure, inlet subcooling, and flooding rate on the heat transfer are investigated. The heat transfer behavior during transition to Inverted Slug Film Boiling (ISFB) regime is studied and is found to be different than that reported in previous studies. The effects of spacer grids on heat transfer in the IAFB and ISFB regimes are also presented. Currently design basis accidents are evaluated with codes in which heat transfer and wall drag must be calculated with local flow parameters. The existing models for heat transfer are applicable up to a void fraction of 0.6, i.e. in the IAFB regime and there is no heat transfer correlation for ISFB. A new semi-empirical heat transfer model is developed covering the IAFB and ISFB regimes which is valid for a void fraction up to 90% using the local flow variables. The mean absolute percentage error in predicting the RBHT data is 11% and root mean square error is 15%. This new semi-empirical model is found to compare well with the reflood data of FLECHT-SEASET experiments as well as data

  20. Studies on superconducting thin films for SRF applications

    SciTech Connect

    Tajima, Tsuyoshi; Haberkorn, Nestor; Civale, Leonardo; Hawley, Marilyn; Schulze, Roland; Zocco, Adam; Eremeev, Grigory; Guo, Jiquan; Dolgashev, Valery; Martin, David; Tantawi, Sami; Yoneda, Charles; Doi, Toshiya; Matsumoto, Akiyoshi

    2010-09-09

    In order to overcome the fundamental limit of Nb's critical magnetic field ({approx} 200 mT) that corresponds to E{sub acc} {approx}50 MV/m, an idea of coating several thin layers of a superconductor has been proposed. MgB{sub 2}, a superconductor that has a T{sub c} of {approx}39 K, has been studied to explore the effect of coating in terms of DC and RF critical magnetic fields, and RF surface losses. MgB{sub 2} has shown an excellent behavior, although there is some discrepancy between DC and RF measurements.

  1. Repeat film analysis and its implications for quality assurance in dental radiology: An institutional case study

    PubMed Central

    Acharya, Shruthi; Pai, Keerthilatha M.; Acharya, Shashidhar

    2015-01-01

    Context: The goal of any radiologist is to produce the highest quality diagnostic radiographs, while keeping patient exposure as low as reasonably achievable (ALARA). Aims: The aim of this study was to describe the reasons for radiograph rejections through a repeat film analysis in an Indian dental school. Settings and Design: An observational study conducted in the Department of Oral Medicine and Radiology, Manipal College of Dental Sciences, Manipal. Materials and Methods: During a 6-month study period, a total of 9,495 intra-oral radiographs and 2339 extraoral radiographs taken in the Radiology Department were subjected to repeat film analysis. Statistical Analysis Used: SPSS Version 16. Descriptive analysis used. Results: The results showed that the repeat rates were 7.1% and 5.86% for intraoral and extraoral radiographs, respectively. Among the causes for errors reported, positioning error (38.7%) was the most common, followed by improper angulations (26.1%), and improper film placement (11.2%) for intra-oral radiographs. The study found that the maximum frequency of repeats among extraoral radiographs was for panoramic radiographs (49%) followed by lateral cephalogram (33%), and paranasal sinus view (14%). It was also observed that repeat rate of intraoral radiographs was highest for internees (44.7%), and undergraduate students (28.2%). Conclusions: The study pointed to a need for more targeted interventions to achieve the goal of keeping patient exposure ALARA in a dental school setting. PMID:26321841

  2. Fluorescence and UV/VIS absorption spectroscopy studies on polymer blend films for photovoltaics

    NASA Astrophysics Data System (ADS)

    van Stam, Jan; Lindqvist, Camilla; Hansson, Rickard; Ericsson, Leif; Moons, Ellen

    2015-08-01

    The quinoxaline-based polymer TQ1 (poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5- diyl]) is a promising candidate as electron donor in organic solar cells. In combination with the electron acceptor [6,6]- phenyl-C71- butyric acid methyl ester (PC70BM), TQ1 has resulted in solar cells with power conversion efficiencies of 7 %. We have studied TQ1 films, with and without PC70BM, spin-casted from different solvents, by fluorescence spectroscopy and UV/VIS absorption spectroscopy. We used chloroform (CF), chlorobenzene (CB), and odichlorobenzene (o-DCB) as solvents for the coating solutions and 1-chloronaphthalene (CN) as solvent additive. CN addition has been shown to enhance photo-conversion efficiency of these solar cells. Phase-separation causes lateral domain formation in the films and the domain size depends on the solvent . These morphological differences coincide with changes in the spectroscopic patterns of the films. From a spectroscopic point of view, TQ1 acts as fluorescent probe and PC70BM as quencher. The degree of fluorescence quenching is coupled to the morphology through the distance between TQ1 and PC70BM. Furthermore, if using a bad solvent for PC70BM, morphological regions rich in the fullerene yield emission characteristic for aggregated PC70BM. Clear differences were found, comparing the TQ1:PC70BM blend films casted from different solvents and at different ratios between the donor and acceptor. The morphology also influences the UV/VIS absorption spectra, yielding further information on the composition. The results show that fluorescence and UV/VIS absorption spectroscopy can be used to detect aggregation in blended films and that these methods extend the morphological information beyond the scale accessible with microscopy.

  3. Switching dynamics of thin film ferroelectric devices - a massively parallel phase field study

    NASA Astrophysics Data System (ADS)

    Ashraf, Md. Khalid

    In this thesis, we investigate the switching dynamics in thin film ferroelectrics. Ferroelectric materials are of inherent interest for low power and multi-functional devices. However, possible device applications of these materials have been limited due to the poorly understood electromagnetic and mechanical response at the nanoscale in arbitrary device structures. The difficulty in understanding switching dynamics mainly arises from the presence of features at multiple length scales and the nonlinearity associated with the strongly coupled states. For example, in a ferroelectric material, the domain walls are of nm size whereas the domain pattern forms at micron scale. The switching is determined by coupled chemical, electrostatic, mechanical and thermal interactions. Thus computational understanding of switching dynamics in thin film ferroelectrics and a direct comparison with experiment poses a significant numerical challenge. We have developed a phase field model that describes the physics of polarization dynamics at the microscopic scale. A number of efficient numerical methods have been applied for achieving massive parallelization of all the calculation steps. Conformally mapped elements, node wise assembly and prevention of dynamic loading minimized the communication between processors and increased the parallelization efficiency. With these improvements, we have reached the experimental scale - a significant step forward compared to the state of the art thin film ferroelectric switching dynamics models. Using this model, we elucidated the switching dynamics on multiple surfaces of the multiferroic material BFO. We also calculated the switching energy of scaled BFO islands. Finally, we studied the interaction of domain wall propagation with misfit dislocations in the thin film. We believe that the model will be useful in understanding the switching dynamics in many different experimental setups incorporating thin film ferroelectrics.

  4. X-ray Photon Correlation Spectroscopy Study on Dynamics of the Free Surface in Entangled Polystyrene Melt Films

    NASA Astrophysics Data System (ADS)

    Koga, Tadanori; Li, Chunhua; Endoh, Maya K.; Narayanan, Suresh; Lurio, Laurence; Sinha, Sunil K.

    2011-01-01

    The dynamics of polymer chains near the surface of a melt and within thin films remains a subject of inquiry along with the nature of the glass transition in these systems. Recent studies show that the properties of the free surface region are crucial in determining the anomalous glass transition temperature (Tg) reduction of polymer thin films. In this study, by embedding "dilute" gold nanoparticles in polystyrene (PS) thin films as "markers", we could successfully probe the diffusive Brownian motion which tracks the local viscosity both at the free surface and within the rest of the single PS thin film far above bulk Tg. The technique used was X-ray photon correlation spectroscopy with resonance-enhanced X-rays that allows us to independently measure the motion in the regions of interest at the nanometer scale. We found the presence of the surface reduced viscosity layer in entangled PS thin films at T>>Tg.

  5. LETTER TO THE EDITOR: Aluminium oxide ultrathin-film growth on the Mo(110) surface: a work-function study

    NASA Astrophysics Data System (ADS)

    Magkoev, T. T.; Vladimirov, G. G.

    2001-07-01

    Submonolayer-to-multilayer films deposited onto the surface of Mo(110) crystal by thermal evaporation of bulk aluminium oxide in ultrahigh vacuum have been studied by Auger electron spectroscopy, low-energy electron diffraction and work-function measurements (the Anderson method). The Auger spectra of the films at all coverages studied are composed of the lines characteristic for the bulk oxide; no evidence of a metallic Al signal is found. The layer-by-layer growth mode occurs up to two monolayers. Increase of the reflectivity of the low-energy electrons (1 to 4 eV) as the film grows indicates that the film has a reduced density of states, which probably resembles the band gap of the bulk alumina. The films deposited on a substrate held at room temperature are amorphous, whereas deposition at 1300 K results in a hexagonal superstructure.

  6. Film ispalators

    SciTech Connect

    Startsev, Aleksandr V; Stoilov, Yurii Yu

    2002-05-31

    New physical objects, ispalators based on free soap films, exhibit persistent flows of the soap solution in open and closed volumes in air with additions of gases of the C{sub 8}F{sub 18} type (p = 20 Torr) at temperature drops on the films of the order of tenths and hundredths of kelvin. The flows move continuously at a velocity of 5 - 20 cm s{sup -1}. It is found that the parts of an inclined ispalator film show anomalous behaviour upon heating: their weight increases and they move downward over the film, whereas the unheated parts of the film move upward. Continuous radial vortex flows accompanied by the formation and washing of the regions of a thin black film are observed on circular films in closed volumes upon their uniform external cooling by evaporating water for 5 - 10 hours. The rapid flows make film ispalators the efficient heat carriers, which operate at small temperature drops (tenths and hundredths of kelvin) and surpass copper in the amount of thermal energy being transferred. The outlook for the further study and applications of film ispalators for detecting thermal fields and laser radiation is discussed. (laser applications and other topics in quantum electronics)

  7. Spectroscopic studies on diamond like carbon films synthesized by pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Panda, Madhusmita; Krishnan, R.; Ravindran, T. R.; Das, Arindam; Mangamma, G.; Dash, S.; Tyagi, A. K.

    2016-05-01

    Hydrogen free Diamond like Carbon (DLC) thin films enriched with C-C sp3 bonding were grown on Si (111) substrates at laser pulse energies varying from 100 to 400 mJ (DLC-100, DLC-200, DLC-300, DLC-400), by Pulsed Laser Ablation (PLA) utilizing an Nd:YAG laser operating at fundamental wavelength. Structural, optical and morphological evolutions as a function of laser pulse energy were studied by micro Raman, UV-Vis spectroscopic studies and Atomic Force Microscopy (AFM), respectively. Raman spectra analysis provided critical clues for the variation in sp3 content and optical energy gap. The sp3 content was estimated using the FWHM of the G peak and found to be in the range of 62-69%. The trend of evolution of sp3 content matches well with the evolution of ID/IG ratio with pulse energy. UV-Vis absorption study of DLC films revealed the variation of optical energy gap with laser pulse energy (1.88 - 2.23 eV), which matches well with the evolution of G-Peak position of the Raman spectra. AFM study revealed that roughness, size and density of particulate in DLC films increase with laser pulse energy.

  8. VOCs in fixed film processes. 2: Model studies

    SciTech Connect

    Parker, W.J.; Monteith, H.D.; Melcer, H.

    1996-07-01

    Under the US Clean Air Act Amendments, fugitive emissions of volatile organic contaminants (VOCs) from waste-water-treatment facilities have been identified as a potentially significant source of air pollution. Models incorporating liquid-gas mass-transfer and biofilm mass-transfer resistances were developed for trickling filters (TF) and rotating biological contractors (RBC). Biodegradation and volatilization coefficients were estimated from the previously described pilot-scale studies. The volatilization coefficients of a given compound in the TF and RBC were generally constant across the experimental conditions investigated. While biodegradation-rate coefficients were constant in the TF across experimental conditions, in the RBC the biodegradation-rate coefficients appeared to be greatest under conditions of low loading and high disc rotation speed and lowest under conditions of high loading and low disk rotational speed. The biofilm was completely penetrated by most of the contaminants and diffusional resistance did not limit the rate of biodegradation of any of the compounds. In the RBC, diffusion in the biofilm appeared to be limiting the biodegradation of toluene, o-xylene, and 1,3,5-trimethylbenzene. The ratio of gas- and liquid-phase mass-transfer coefficients ranged from 91.4 for the TF to 5.6 for the RBC. Due to the relatively wide confidence intervals associated with these estimates, the values could not be statistically differentiated, however, the results suggest a significant contribution of gas-phase resistance to mass transfer in some cases.

  9. VOCs in fixed film processes. I: Pilot studies

    SciTech Connect

    Parker, W.J.; Monteith, H.D.; Melcer, H.

    1996-07-01

    Stripping of volatile organic contaminants (VOCs) during wastewater treatment is of concern due to the potential of these compounds to contribute to stratospheric ozone depletion, ground-level smog formation, chronic toxicity to exposed workers, and odors. A study of the fate of volatile organic contaminants (VOCs) in trickling filters (TF) and rotating biological contactors (RBC) was performed. Of the target compounds investigated, tetrachloroethylene was volatilized to the greatest extent, while 1,1,2,2-tetrachloroethane was the least volatilized in the TF and bromoform was least volatilized in the RBC. Toulene, o-xylene and 1,3,5-trimethylbenzene were biodegraded to the greatest extent and 1,1,2,2-tetrachloroethane was least biodegraded. Increasing the hydraulic loading tended to increase the proportion of influent VOCs found in the TF effluent. Imposing effluent recycle on the TF increased the fraction of influent VOCs found in the effluent, but also decreased the fraction stripped and increased the fraction that was biodegraded. Increasing hydraulic loading to the RBC tended to increase the proportion of influent VOCs found in the effluent and off-gas. Increasing the RBC disc rotational speed increased the fraction that was biodegraded and decreased the fraction of VOCs found in the effluent and off-gas streams. The TF tended to have greater losses to volatilization than the RBC while the RBC maintained a greater fraction of the candidate VOCs in the process effluent than the TF. Differences between the processes with respect to biodegradation could not be inferred.

  10. Theoretical and material studies on thin-film electroluminescent devices

    NASA Technical Reports Server (NTRS)

    Summers, C. J.; Brennan, K. F.

    1986-01-01

    A theoretical study of resonant tunneling in multilayered heterostructures is presented based on an exact solution of the Schroedinger equation under the application of a constant electric field. By use of the transfer matrix approach, the transmissivity of the structure is determined as a function of the incident electron energy. The approach presented is easily extended to many layer structures where it is more accurate than other existing transfer matrix or WKB models. The transmission resonances are compared to the bound state energies calculated for a finite square well under bias using either an asymmetric square well model or the exact solution of an infinite square well under the application of an electric field. The results show good agreement with other existing models as well as with the bound state energies. The calculations were then applied to a new superlattice structure, the variablly spaced superlattice energy filter, (VSSEP) which is designed such that under bias the spatial quantization levels fully align. Based on these calculations, a new class of resonant tunneling superlattice devices can be designed.

  11. NMR studies of Phase Transitions in Alkali Metal Films on Glass Substrates

    NASA Astrophysics Data System (ADS)

    Ishikawa, K.; Patton, B.; Jau, Y.-Y.; Happer, W.

    2006-05-01

    We report NMR spectra of thin ^87Rb films on glass in an investigation of the ``curing'' process which is commonly observed in alkali cells. The cells were cycled in temperature over a range of 5 C to 170 C and the rubidium solid-liquid phase transition was studied. The spectra of these two phases are resolvable at 9.4 T because of their different Knight shifts. Hysteresis in the observed phases confirmed reports of a curing phenomenon, and after time a supercooled liquid Rb peak could be detected at temperatures far below the predicted freezing point of 39 C. Moreover, a third NMR peak was observed at temperatures below the melting point whose frequency varied with temperature and spanned the solid and liquid frequency ranges. To our knowledge, this is the first study to characterize this additional resonance. We have also performed analogous measurements on ^133Cs films.

  12. Charge-magnetic interference resonant scattering studies of ferromagnetic crystals and thin films

    SciTech Connect

    Haskel, D.; Kravtsov, E.; Choi, Y.; Lang, J.C.; Islam, Z.; Srajer, G.; Jiang, J.S.; Bader, S.D.; Canfield, Paul C.

    2012-06-15

    The element- and site-specificity of X-ray resonant magnetic scattering (XRMS) makes it an ideal tool for furthering our understanding of complex magnetic systems. In the hard X-rays, XRMS is readily applied to most antiferromagnets where the relatively weak resonant magnetic scattering (10 −2–10 −6Ic) is separated in reciprocal space from the stronger, Bragg charge scattered intensity, Ic. In ferro(ferri)magnetic materials, however, such separation does not occur and measurements of resonant magnetic scattering in the presence of strong charge scattering are quite challenging. We discuss the use of charge-magnetic interference resonant scattering for studies of ferromagnetic (FM) crystals and layered films. We review the challenges and opportunities afforded by this approach, particularly when using circularly polarized X-rays.We illustrate current capabilities at the Advanced Photon Source with studies aimed at probing site-specific magnetism in ferromagnetic crystals, and interfacial magnetism in films.

  13. Optical, structural and electrochromic behavior studies on nanocomposite thin film of aniline, o-toluidine and WO3

    NASA Astrophysics Data System (ADS)

    Najafi-Ashtiani, Hamed; Bahari, Ali

    2016-08-01

    In the field of materials for electrochromic (EC) applications much attention was paid to the derivatives of aniline. We report on the optical, structural and electrochromic properties of electrochromic thin film based on composite of WO3 nanoparticles and copolymer of aniline and o-toluidine prepared by electrochemical polymerization method on fluorine doped tin oxide (FTO) coated glass. The thin film was studied by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectroscopy. The morphology of prepared thin film was characterized by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and the thermal gravimetric analysis (TGA) as well. The optical spectra of nanocomposite thin film were characterized in the 200-900 nm wavelength range and EC properties of nanocomposite thin film were studied by cyclic voltammetry (CV). The calculation of optical band gaps of thin film exhibited that the thin film has directly allowed transition with the values of 2.63 eV on first region and 3.80 eV on second region. Dispersion parameters were calculated based on the single oscillator model. Finally, important parameters such as dispersion energy, oscillator energy and lattice dielectric constant were determined and compared with the data from other researchers. The nonlinear optical properties such as nonlinear optical susceptibility, nonlinear absorption coefficient and nonlinear refractive index were extracted. The obtained results of nanocomposite thin film can be useful for the optoelectronic applications.

  14. A comparative study of the morphology of flow and spin coated P3HT:PCBM films

    NASA Astrophysics Data System (ADS)

    Chapa, Jose; Karim, Alamgir

    2013-03-01

    Polymer solar cells are attractive due to the possibility of using cheaper materials and processing techniques for mass production of solar panels. Previous methods of fabricating polymer solar cells are suitable in laboratory conditions but are not scalable for industrial production. In this study, thin films of the photoactive blend of poly(3-hexylthiophene) (P3HT) and fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were prepared by flow coating, which is suitable for industrial manufacturing of solar cells. P3HT:PCBM blends were cast from different solvents, and the morphology of flow coated and spin coated films was compared. The surface morphology and optical properties of P3HT:PCBM films were characterized with optical microscopy, AFM, and UV-vis absorption spectroscopy. The degree of P3HT order was higher in flow coated films, as compared to spin coated films. Films flow coated using chloroform solutions had a higher thermal stability and an enhanced degree of phase separation as compared to spin coated films. Flow coated films from chlorobenzene solutions had a lower thermal stability and a smaller length scale of phase separation. This study demonstrates that flow coating is a suitable alternative technique for fabricating polymer solar cells. Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE- AC02-98CH10886

  15. Studies of the Superconducting Transition in the Mo/Au-Bilayer Thin Films

    NASA Technical Reports Server (NTRS)

    Sadleir, John; Smith, Stephen; Iyomoto, naoko; Bandler, Simon; Chervenak, Jay; Brown, Ari; Brekowsky, Regis; Kilbourne, Caroline; Robinson, Ian

    2007-01-01

    At NASA Goddard, microcalorimeter arrays using superconducting transition edge sensor thermometers (TESs) are under development for high energy resolution X-ray astrophysics applications. We report on our studies of the superconducting transition in our Mo/Au-bilayer TES films including: low current measurements of the superconducting bilayer's resistance transition versus temperature on pixels with different normal metal absorber attachment designs and measured temperature scaling of the critical current and critical magnetic field.

  16. Thin Films

    NASA Astrophysics Data System (ADS)

    Khorshidi, Zahra; Bahari, Ali; Gholipur, Reza

    2014-11-01

    Effect of annealing temperature on the characteristics of sol-gel-driven Ta ax La(1- a) x O y thin film spin-coated on Si substrate as a high- k gate dielectric was studied. Ta ax La(1- a) x O y thin films with different amounts of a were prepared (as-prepared samples). X-ray diffraction measurements of the as-prepared samples indicated that Ta0.3 x La0.7 x Oy film had an amorphous structure. Therefore, Ta0.3 x La0.7 x O y film was chosen to continue the present studies. The morphology of Ta0.3 x La0.7 x O y films was studied using scanning electron microscopy and atomic force microscopy techniques. The obtained results showed that the size of grain boundaries on Ta0.3 x La0.7 x O y film surfaces was increased with increasing annealing temperature. Electrical and optical characterizations of the as-prepared and annealed films were investigated as a function of annealing temperature using capacitance-voltage ( C- V) and current density-voltage ( J- V) measurements and the Tauc method. The obtained results demonstrated that Ta0.3 x La0.7 x O y films had high dielectric constant (≈27), wide band gap (≈4.5 eV), and low leakage current density (≈10-6 A/cm2 at 1 V).

  17. Testing the Effectiveness of 3D Film for Laboratory-Based Studies of Emotion

    PubMed Central

    Bride, Daniel L.; Crowell, Sheila E.; Baucom, Brian R.; Kaufman, Erin A.; O'Connor, Caitlin G.; Skidmore, Chloe R.; Yaptangco, Mona

    2014-01-01

    Research in psychology and affective neuroscience often relies on film as a standardized and reliable method for evoking emotion. However, clip validation is not undertaken regularly. This presents a challenge for research with adolescent and young adult samples who are exposed routinely to high-definition (HD) three-dimensional (3D) stimuli and may not respond to older, validated film clips. Studies with young people inform understanding of emotional development, dysregulated affect, and psychopathology, making it critical to assess whether technological advances improve the study of emotion. In the present study, we examine whether 3D film is more evocative than 2D using a tightly controlled within-subjects design. Participants (n  =  408) viewed clips during a concurrent psychophysiological assessment. Results indicate that both 2D and 3D technology are highly effective tools for emotion elicitation. However, 3D does not add incremental benefit over 2D, even when individual differences in anxiety, emotion dysregulation, and novelty seeking are considered. PMID:25170878

  18. Testing the effectiveness of 3D film for laboratory-based studies of emotion.

    PubMed

    Bride, Daniel L; Crowell, Sheila E; Baucom, Brian R; Kaufman, Erin A; O'Connor, Caitlin G; Skidmore, Chloe R; Yaptangco, Mona

    2014-01-01

    Research in psychology and affective neuroscience often relies on film as a standardized and reliable method for evoking emotion. However, clip validation is not undertaken regularly. This presents a challenge for research with adolescent and young adult samples who are exposed routinely to high-definition (HD) three-dimensional (3D) stimuli and may not respond to older, validated film clips. Studies with young people inform understanding of emotional development, dysregulated affect, and psychopathology, making it critical to assess whether technological advances improve the study of emotion. In the present study, we examine whether 3D film is more evocative than 2D using a tightly controlled within-subjects design. Participants (n  =  408) viewed clips during a concurrent psychophysiological assessment. Results indicate that both 2D and 3D technology are highly effective tools for emotion elicitation. However, 3D does not add incremental benefit over 2D, even when individual differences in anxiety, emotion dysregulation, and novelty seeking are considered. PMID:25170878

  19. Analysis on superhydrophobic silver decorated copper Oxide nanostructured thin films for SERS studies.

    PubMed

    Jayram, Naidu Dhanpal; Aishwarya, D; Sonia, S; Mangalaraj, D; Kumar, P Suresh; Rao, G Mohan

    2016-09-01

    The present work demonstrates the superhydrophobic and Surface Enhanced Raman Spectroscopy (SERS) active substrate performance of silver coated copper oxide (Ag@CuO) nanostructured thin films prepared by the SILAR process. Super hydrophobic substrates that combine super hydrophobic condensation effect and high enhancement ability of Ag@CuO nanoflowers are investigated for SERS studies. The possible growth mechanism for the formation of nanoflower arrays from nanospindles has been discussed. Morphology and crystallinity of the Ag@CuO thin films are confirmed using FESEM and XRD. The results obtained in the present study indicate that the as-deposited hydrophobic nanospindles structure converts to super hydrophobic nanoflower arrays on annealing at 200°C. The Ag@CuO super hydrophobic nanoflowers thin film based SERS substrates show highly enhanced Raman spectra with an EF value of 2.0×10(7) for (Rhodamine 6G) R6G, allowing a detection limit from a 10(-10)molL(-1) solution. The present study may provide a new perception in fabricating efficient super hydrophobic substrates for SERS, suggesting that the fabricated substrates are promising candidates for trace analysis of R6G dye and are expected to be widely used as highly sensitive SERS active substrates for various toxic dyes in the future. PMID:27294970

  20. Study of water vapour permeability of protein and gum-based edible films by a photothermal method

    NASA Astrophysics Data System (ADS)

    Tomás, S. A.; Saavedra, R.; Cruz, A.; Pedroza-Islas, R.; San Martín, E.

    2005-06-01

    The water vapour permeability of protein and gum-based edible films was studied by means of a photothermal method. The films were prepared with two basic ingredients, whey protein concentrate and mesquite gum, according to the proportions 75:25, 50:50, 25:75, and 0:100 (weight:weight). The water vapour diffusion coefficient of the analyzed films was found within the interval 0.37 × 10-6 to 2.04 × 10-6 cm^2/s, increasing linearly by increasing the mesquite gum composition in the films. The incorporation of mesquite gum in films produces less effective moisture barriers due to its highly hydrophilic property.

  1. Study on micro structural and electrical properties of FeCl3 doped HPMC/PVP polymer blend films

    NASA Astrophysics Data System (ADS)

    Somashekarappa, H.; Prakash, Y.; Urs, R. Gopal Krishne; Somashekar, R.

    2015-06-01

    Solid polymer electrolyte (SPE) based on Hydroxypropylemethylcellulose (HPMC) and Polyvinylpyrrolidone (PVP) polymer blend films complexed with different weight ratio of FeCl3 were prepared using solution casting method and investigated using X-ray line profile analysis. Here an attempt has been made to study the changes in crystal imperfection parameters in HPMC/PVP blend films with the increase in concentration of FeCl3. The obtained results shows that decrease in micro crystalline parameters results in increase in the amorphous nature of the film yields more flexibility, biodegradability and good ionic conductivity. AC conductivity measurements in these films show that the conductivity increases as the concentration of FeCl3 increases. These films were suitable for electro chemical applications.

  2. A study on the nonlinear microwave electrodynamic response of e-beam evaporated MgB2 superconducting thin films

    NASA Astrophysics Data System (ADS)

    Andreone, A.; Di Gennaro, E.; Lamura, G.; Salluzzo, M.; Purnell, A.; Cohen, L. F.; Hao, L.; Gallop, J.; Cantoni, C.; Paranthaman, M.

    2003-02-01

    We present a study on the temperature and field dependence of the microwave surface impedance Zs in thin films of the superconducting MgB2 compound. Samples were prepared by e-beam evaporation of boron on r-plane sapphire followed by an ex situ annealing in Mg vapour. Critical temperature values range between 26 and 38 K. Surface impedance measurements (Zs = Rs + iXs) were performed from 2 K close to Tc in the microwave region up to 20 GHz via parallel plate or dielectrically loaded resonators in 'symmetric' (two MgB2 films) and asymmetric (an MgB2 film and a commercial YBCO control film) configurations. At high microwave power, frequency domain measurements show a characteristic signature associated with weak links and this appears to be the limiting factor governing the performance of these films.

  3. Corrosion protection of copper by polypyrrole film studied by electrochemical impedance spectroscopy and the electrochemical quartz microbalance

    NASA Astrophysics Data System (ADS)

    Lei, Yanhua; Ohtsuka, Toshiaki; Sheng, Nan

    2015-12-01

    Polypyrrole (PPy) films were synthesized on copper in solution of sodium di-hydrogen phosphate and phytate for corrosion protection. The protection properties of PPy films were comparatively investigated in NaCl solution. During two months immersion, the PPy film doped with phytate anions, working as a cationic perm-selective membrane, inhibited the dissolution of copper to 1% of bare copper. Differently, the PPy film doped with di-hydrogen phosphate anions, possessing anionic perm-selectivity, was gradually reduced, and inhibited the dissolution to 7.8% of bare copper. Degradation of the PPy films was studied by comparing the electrochemical impedance spectroscopy change at different immersion time and Raman spectra change after immersion.

  4. Surface topographic study of chalcogenide thin films of GexSb(As)₄₀-xS₅₀Te₁₀ glasses.

    PubMed

    Anastasescu, M; Gartner, M; Szekeres, A; Pamukchieva, V

    2014-04-01

    The surface topography and fractal properties of GexSb(As)40-xS50Te10 (x=10, 20, 27 at.%) films, evaporated onto glass substrates, have been studied by atomic force microscopic imaging at different scales. The surface of the chalcogenide films is smooth (<5 nm roughness), isotropic and having some particular differences in texture. All films are self-similar with Mean Fractal Dimension in the range of 2.25-2.63. The films with GexSb40-xS50Te10 composition are more uniform in terms of surface morphology (grains structure) than those with GexAs40-xS50Te10 composition for which the film surface exhibits a superimposed structure of large particles at x=10 and 20 at.%. PMID:24530358

  5. Study of Fluorine Addition Influence in the Dielectric Constant of Diamond-Like Carbon Thin Film Deposited by Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Trippe, S. C.; Mansano, R. D.

    The hydrogenated amorphous carbon films (a-C:H) or DLC (Diamond-Like Carbon) films are well known for exhibiting high electrical resistivity, low dielectric constant, high mechanical hardness, low friction coefficient, low superficial roughness and also for being inert. In this paper, we produced fluorinated DLC films (a-C:F), and studied the effect of adding CF4 on the above-mentioned properties of DLC films. These films were produced by a reactive RF magnetron sputtering system using a target of pure carbon in stable graphite allotrope. We performed measurements of electrical characteristic curves of capacitance as a function of applied tension (C-V) and current as a function of the applied tension (I-V). We showed the dielectric constant (k) and the resistivity (ρ) as functions of the CF4 concentration. On films with 65% CF4, we found that k = 2.7, and on films with 70% CF4, ρ = 12.3 × 1011 Ω cm. The value of the electrical breakdown field to films with 70% CF4 is 5.3 × 106 V/cm.

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

    NASA Astrophysics Data System (ADS)

    Al Din, Nasser Saad; Hussain, Nabiha; Jandow, Nidhal

    2016-07-01

    Lead (II) Sulfide PbS thin films were deposited on glass substrates at 25°C by chemical bath deposition (CBD) method. The structural properties of the films were studied as a function of the concentration of Thiourea (CS (NH2)2) as Source of Sulfide and deposition time. The surface morphology of the films was characterized by X-ray diffraction and SEM. The obtained results showed that the as-deposited films Polycrystalline had cubic crystalline phase that belong to S.G: Fm3m. We found that they have preferred orientation [200]. Also the thickness of thin films decrease with deposition time after certain value and, it observed free sulfide had orthorhombic phase. Optical properties showed that the thin films have high transmission at visible range and low transmission at UV, IR range. The films of PbS have direct band gap (I.68 - 2.32 ev) at 300K the values of band energy decreases with increases thickness of the Lead (II) Sulfide films.

  7. "Star Wars", Model Making, and Cultural Critique: A Case for Film Study in Art Classrooms

    ERIC Educational Resources Information Center

    Briggs, Judith

    2009-01-01

    Films are multimodal, often memorable, and change one's way of thinking. Films provide narratives and visual metaphors that function as tools for one's imagination and learning. No other film has amplified this phenomenon in the United States more than the "Star Wars" Cycle. "Star Wars" exemplifies the multidimensionality of the film industry, its…

  8. Study of Nonlinear MHD Tribological Squeeze Film at Generalized Magnetic Reynolds Numbers Using DTM.

    PubMed

    Rashidi, Mohammad Mehdi; Freidoonimehr, Navid; Momoniat, Ebrahim; Rostami, Behnam

    2015-01-01

    In the current article, a combination of the differential transform method (DTM) and Padé approximation method are implemented to solve a system of nonlinear differential equations modelling the flow of a Newtonian magnetic lubricant squeeze film with magnetic induction effects incorporated. Solutions for the transformed radial and tangential momentum as well as solutions for the radial and tangential induced magnetic field conservation equations are determined. The DTM-Padé combined method is observed to demonstrate excellent convergence, stability and versatility in simulating the magnetic squeeze film problem. The effects of involved parameters, i.e. squeeze Reynolds number (N1), dimensionless axial magnetic force strength parameter (N2), dimensionless tangential magnetic force strength parameter (N3), and magnetic Reynolds number (Rem) are illustrated graphically and discussed in detail. Applications of the study include automotive magneto-rheological shock absorbers, novel aircraft landing gear systems and biological prosthetics. PMID:26267247

  9. Study of Nonlinear MHD Tribological Squeeze Film at Generalized Magnetic Reynolds Numbers Using DTM

    PubMed Central

    Rashidi, Mohammad Mehdi; Freidoonimehr, Navid; Momoniat, Ebrahim; Rostami, Behnam

    2015-01-01

    In the current article, a combination of the differential transform method (DTM) and Padé approximation method are implemented to solve a system of nonlinear differential equations modelling the flow of a Newtonian magnetic lubricant squeeze film with magnetic induction effects incorporated. Solutions for the transformed radial and tangential momentum as well as solutions for the radial and tangential induced magnetic field conservation equations are determined. The DTM-Padé combined method is observed to demonstrate excellent convergence, stability and versatility in simulating the magnetic squeeze film problem. The effects of involved parameters, i.e. squeeze Reynolds number (N1), dimensionless axial magnetic force strength parameter (N2), dimensionless tangential magnetic force strength parameter (N3), and magnetic Reynolds number (Rem) are illustrated graphically and discussed in detail. Applications of the study include automotive magneto-rheological shock absorbers, novel aircraft landing gear systems and biological prosthetics. PMID:26267247

  10. Study of degraded neutron spectra through metal matrix composites using CR-39 films

    NASA Astrophysics Data System (ADS)

    Gopalani, Deepak; Kumar, S.; Ramaseshu, P.; Sundaram, V. K.; Mehta, S. K.

    1998-06-01

    Considerable interest has grown in the last decade in the use of CR-39 films in routine neutron monitoring and dosimetry. In addition, work in neutron spectrometry has been undertaken by various workers ( Decossas et al., 1984; Faermann et al., 1983; Fews et al., 1984; Turner et al., 1984). In the present study metal matrix composites (MMC) samples of Pb-Li, Pb-Cd, Al-Li and Al-B 4C were prepared by using powder metallurgy and alloying elements techniques. The density was obtained for these MMC samples in the range of 80-90% of the metal density. Degraded neutron spectra were obtained by exposing these samples to a 252Cf source housed in a camera and the detector used was CR-39 films covered with a 1 mm PE radiator. These spectra have also been validated through Monte Carlo Neutron and Photon Transport Code (1983).

  11. Efficient and large scale synthesis of graphene from coal and its film electrical properties studies.

    PubMed

    Wu, Yingpeng; Ma, Yanfeng; Wang, Yan; Huang, Lu; Li, Na; Zhang, Tengfei; Zhang, Yi; Wan, Xiangjian; Huang, Yi; Chen, Yongsheng

    2013-02-01

    Coal, which is abundant and has an incompact structure, is a good candidate to replace graphite as the raw material for the production of graphene. Here, a new solution phase technique for the preparation of graphene from coal has been developed. The precursor: graphene oxide got from coal was examined by atomic force microscopy, dynamic light scattering and X-ray diffraction, the results showed the GO was a small and single layer sheet. The graphene was examined by X-ray photoelectron spectroscopy, and Raman spectroscopy. Furthermore, graphene films have been prepared using direct solution process and the electrical conductivity and Hall effect have been studied. The results showed the conductivity of the films could reach as high as 2.5 x 10(5) Sm(-1) and exhibited an n-type behavior. PMID:23646544

  12. Infrared absorption study of hydrogen incorporation in thick nanocrystalline diamond films

    SciTech Connect

    Tang, C.J.; Neves, A.J.; Carmo, M.C.

    2005-05-30

    We present an infrared (IR) optical absorbance study of hydrogen incorporation in nanocrystalline diamond films. The thick nanocrystalline diamond films were synthesized by microwave plasma-assisted chemical vapor deposition and a high growth rate about 3.0 {mu}m/h was achieved. The morphology, phase quality, and hydrogen incorporation were assessed by means of scanning electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). Large amount of hydrogen bonded to nanocrystalline diamond is clearly evidenced by the huge CH stretching band in the FTIR spectrum. The mechanism of hydrogen incorporation is discussed in light of the growth mechanism of nanocrystalline diamond. This suggests the potential of nanocrystalline diamond for IR electro-optical device applications.

  13. The Study of Interpenetration Length between dPS Films and PS-grafted Layers

    NASA Astrophysics Data System (ADS)

    Lee, Hoyeon; Jo, Seongjun; Hirata, Toyoaki; Yamada, Norifumi L.; Tanaka, Keiji; Ryu, Du Yeol

    In polymer thin film system, the type of interfacial interaction is a critical parameter to determining the thermal and physical properties of polymer films. Interestingly, the interfacial energy of grafted substrates with polymer chains is remarkably altered by simply controlling grafting density, which has been referred to as autophobicity. In this study, we investigated the interpenetrating interfaces between deuterated polystyrene (dPS) and grafted substrates with the same chemical identity. PS-grafted substrates were prepared using a grafting-to approach with hydroxyl end-functionalized polystyrene (PSOH) in a dry brush regime, where the brush thickness and grafting density were determined based on the chain length (or molecular weight, Mn) of PSOHs. The interpenetration lengths (ξ) at interfaces between dPS and PS-grafted layers were characterized using neutron reflectivity (NR) measurements (performed at the SOFIA beam-line at J-PARC, Japan). Academic adviser.

  14. Time-resolved photoluminescence study of m-plane GaN thin films

    NASA Astrophysics Data System (ADS)

    Pan, Ji-Hong; Jang, Der-Jun; Quadir, Shaham; Lo, Ikai

    2014-03-01

    The optical properties and the carrier relaxation of GaN thin films were studied by time-resolved photoluminescence apparatus. The m-plane GaN thin films were grown on GaN buffer layer and γ-LiAlO2 substrates by molecular beam epitaxy with variation of N/Ga ratio. We found that the PL associated with defect is prominent for large N/Ga ratio due to the increasing of stacking faults. The intensity of PL perpendicular to the GaN [0001] direction is more intensive than that of PL parallel to the perpendicular to the GaN [0001] direction. The PL decay times exhibit dependence on the direction of the PL polarizations.

  15. Combined theoretical studies of the optical characteristics of II-IV-V2 semiconductor thin films

    NASA Astrophysics Data System (ADS)

    Boukabrine, F.; Chiker, F.; Miloua, R.; Kebbab, Z.; Khenata, R.; Prakash, Deo; Bin Omran, S.; Verma, K. D.

    2016-04-01

    The optical absorbance of four ternary thin films, i.e. MgSiP2, MgGeP2, MgSiAs2, MgGeAs2 have been theoretically examined over a wide range of wavelength from 300 nm to 800 nm. The combination of first-principle electronic structure calculations and the optical matrix approach for modeling the multilayer assembly have been employed for theoretical studies. The analysis of the calculated absorbance spectra at room temperature with unpolarized light and normal incidence, revealed that MgGeAs2 with a direct energy band gap of 1.6 eV exhibit a considerable high optical absorption, where a thickness of 3.2 μm of this thin film is sufficient to absorb 90% of the incident light and generates a maximum photocurrent of ∼23 mA/cm2.

  16. First-principles study of bismuth films at transition-metal grain boundaries

    NASA Astrophysics Data System (ADS)

    Gao, Qin; Widom, Michael

    2014-10-01

    Recent experiments suggest that Bi impurities segregate to form bilayer films on Ni and Cu grain boundaries (GBs) but do not segregate in Fe. To explain these phenomena, we study the total energies of Bi films on transition-metal (TM) Σ3(111) and Σ5(012) GBs using density functional theory. Our results agree with the observed stabilities. We propose a model to predict Bi bilayer stability at Ni GBs which suggests that Bi bilayer is not stable on (111) twist CSL GBs but is stable in most (100) twist CSL GBs. We investigate the interaction and bonding character between Bi and TMs to explain the differences among TMs based on localization of orbitals and magnetism, as well as evaluating the contribution of interfacial phonons at high temperature.

  17. First Principles Study of Bismuth Films at Transition Metal Grain Boundaries

    NASA Astrophysics Data System (ADS)

    Gao, Qin; Widom, Michael

    2014-03-01

    Recent experiments suggest that Bi impurities segregate to form bilayer films on Ni and Cu grain boundaries but do not segregate in Fe. To explain these phenomena, we study the total energies of Bi films on transition metal (TM) Σ3(111) and Σ5(012) grain boundaries (GBs) using density functional theory. Our results agree with the observed stabilities. We propose a model to predict Bi bilayer stability at Ni GBs which suggests that Bi bilayer is not thermodynamically stable on low energy (111) twist CSL GBs but is stable in most (100) twist CSL GBs. We investigated the interaction and bonding character between Bi and TMs to explain the differences among TMs based on localization of orbitals and magnetism. Financial support from the ONR-MURI under the grant NO. N00014-11-1-0678 is gratefully acknowledged.

  18. Studying the Performance of Conductive Polymer Films as Textile Electrodes for Electrical Bioimpedance Measurements

    NASA Astrophysics Data System (ADS)

    Cunico, F. J.; Marquez, J. C.; Hilke, H.; Skrifvars, M.; Seoane, F.

    2013-04-01

    With the goal of finding novel biocompatible materials suitable to replace silver in the manufacturing of textile electrodes for medical applications of electrical bioimpedance spectroscopy, three different polymeric materials have been investigated. Films have been prepared from different polymeric materials and custom bracelets have been confectioned with them. Tetrapolar total right side electrical bioimpedance spectroscopy (EBIS) measurements have been performed with polymer and with standard gel electrodes. The performance of the polymer films was compared against the performance of the gel electrodes. The results indicated that only the polypropylene 1380 could produce EBIS measurements but remarkably tainted with high frequency artefacts. The influence of the electrode mismatch, stray capacitances and large electrode polarization impedance are unclear and they need to be clarified with further studies. If sensorized garments could be made with such biocompatible polymeric materials the burden of considering textrodes class III devices could be avoided.

  19. Modeling studies of the chemical vapor deposition of boron films from B 2H 6

    NASA Astrophysics Data System (ADS)

    Lamborn, Daniel R.; Snyder, David W.; Xi, X. X.; Redwing, Joan M.

    2007-02-01

    The effect of growth conditions on the chemical vapor deposition of boron thin films from diborane (B 2H 6) was investigated using a combination of experimental studies and computational fluid dynamics-based reactor modeling. A multi-physics computational model was developed to simulate the thermal-fluid environment in the reactor. The proposed chemistry model incorporated into the simulations includes gas-phase decomposition and formation of B 2H 6 and surface adsorption and reaction of borane (BH 3). The model accurately predicts the experimentally measured temperature and partial pressure dependence of the boron growth rate using the sticking coefficient of BH 3 on the growth surface as the only adjustable parameter in the calculations. The results indicate that at lower growth temperatures (<500 °C) the boron growth rate is limited by gas-phase kinetics while at higher temperatures (>500 °C) the growth rate is limited by mass transfer of BH 3 to the substrate surface. The studies of boron thin film growth are relevant to the deposition of superconducting MgB 2 thin films, in which B 2H 6 is used as the boron precursor.

  20. Effects of bioactive monoterpenic ketones on membrane organization. A langmuir film study.

    PubMed

    Mariani, María Elisa; Sánchez-Borzone, Mariela E; García, Daniel A

    2016-06-01

    The cyclic ketones, thujone and dihydrocarvone, are lipophilic components of essential oils extracted from different plants, which have proven insecticidal activity. The GABAA receptor is activated by the neurotransmitter GABA and is the action site of widely used neurotoxic pesticides. Many compounds that regulate GABAA receptor function interact with membrane lipids, causing changes in their physical properties and consequently, in the membrane dynamic characteristics that modulate receptor macromolecules. In the present study, the biophysical effects of thujone (a gabaergic reference compound) and dihydrocarvone (structurally very similar) were explored by using monomolecular films of DPPC as a model membrane system, to gain insight into membrane-drug interaction. The compression isotherms showed that both ketones expand the DPPC isotherms and increase membrane elasticity. They penetrate the monolayer but their permanence depends on the possibility of establishing molecular interactions with the film component, favored by defects present in the membrane at the phase transition. Finally, by using Brewster angle microscopy (BAM) as a complementary technique for direct visualization of the study films, we found that incorporating ketone seems to reduce molecular repulsion among phospholipid headgroups. Our results reinforce the notion that changes in membrane mechanics may be occurring in the presence of the assayed ketones, suggesting that their interaction with the receptor's surrounding membrane may modulate or affect its functionality, possibly as part of the mechanism of the bioactivity described for thujone and DHC. PMID:27174212

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

    NASA Astrophysics Data System (ADS)

    Lahariya, Vikas

    2016-05-01

    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 3.4eV. From the Photoluminescence study a broad peak at 435 nm has been observed in violet blue region due to recombination of surface states.

  2. Study of the Electrodynamic Response of MgB2 Sintered Pellets and Thin Films

    NASA Astrophysics Data System (ADS)

    Andreone, A.; di Gennaro, E.; Lamura, G.; Salluzzo, M.; Le Cochec, J.; Gauzzi, A.; Cantoni, C.; Paranthaman, M.; Ceresara, S.; Giunchi, G.

    We present a number of experimental results on the temperature dependence of the magnetic penetration depth λ and on the temperature and field dependence of the microwave surface impedance Zs=Rs+iXs in both pellets and thin films of MgB2, exhibiting critical temperatures ranging between 26 and 38 K. Accurate measurements of Zs(H,T) were performed by means of a sapphire dielectrically loaded cavity operating in the microwave region (20 GHz). The study of λ(T) was carried out employing a single coil mutual inductance technique in the MHz region. An anisotropic s-wave BCS model can account for the temperature dependence experimentally observed in the penetration depth data of the best films, confirming previous reports on the conventional nature of superconductivity in diborides. On the contrary, films having a reduced value of the critical temperature and pellets show no evidence of saturation, and the experimental results strictly follow a quadratic dependence down to the lowest temperatures. We explain this behavior with the presence of metallic Mg inclusions that may locally depress the gap. The study of the surface impedance versus temperature and field shows also that the source of microwave loss can be markedly different, depending on the structural and transport properties of the samples.

  3. A method to study the history of a double oxide film defect in liquid aluminum alloys

    NASA Astrophysics Data System (ADS)

    Raiszadeh, R.; Griffiths, W. D.

    2006-12-01

    Entrained double oxide films have been held responsible for reductions in mechanical properties in aluminum casting alloys. However, their behavior in the liquid metal, once formed, has not been studied directly. It has been proposed that the atmosphere entrapped in the double oxide film defect will continue to react with the liquid metal surrounding it, perhaps leading to its elimination as a significant defect. A silicon-nitride rod with a hole in one end was plunged into liquid aluminum to hold a known volume of air in contact with the liquid metal at a constant temperature. The change in the air volume with time was recorded by real-time X-ray radiography to determine the reaction rates of the trapped atmosphere with the liquid aluminum, creating a model for the behavior of an entrained double oxide film defect. The results from this experiment showed that first oxygen, and then nitrogen, was consumed by the aluminum alloy, to form aluminum oxide and aluminum nitride, respectively. The effect of adding different elements to the liquid aluminum and the effect of different hydrogen contents were also studied.

  4. Study of W/WC films produced by plasma assisted vacuum arc discharge

    NASA Astrophysics Data System (ADS)

    Ospina, R.; Arango, P.; Arango, Y. C.; Restrepo, E.; Devia, A.

    2005-08-01

    W/WC films were grown by the PAPVD repetitive pulsed vacuum arc technique on 304 stainless steel substrates. To produce the coatings, a target of W with purity of 99.9999% was used. The system is composed by a reaction chamber with two opposite electrodes placed inside it. The target is located on the cathode and the samples on the anode. A pulsed power supply is used to generate the discharge. For the production of the W layer, the chamber was filled with Ar gas at a pressure of 3 mbar, and the voltage of the discharge was 270 V with 3 pulses. WC films were grown in an atmosphere of methane at 3 mbar and a voltage discharge of 275 V with 4 pulses. The active and passive times of the discharge were 1 s and 0.5 s, respectively.XRD technique was employed to study the coatings, to study the present phases and the crystallographic orientation of the films, the XRD analyses were carried out varying the temperature of the system-coating-substrate between room temperature and 600 °C, when the WC coatings are degradated, leaving just the tugsten. XPS analyses present the apparition of WC, WO and WO2 compounds. AFM analyses allowed to measure the morphological properties and the thickness around 3 μm.

  5. Electrochromism in metal oxide films studied by Raman spectroscopy and A.C. techniques: charge insertion mechanism

    NASA Astrophysics Data System (ADS)

    Cordoba de Torresi, Susana I.; Takenouti, H.

    1990-08-01

    Two different types of electrochromic nickel oxide films are studied : nickel hydroxide films prepared by cathodic precipitation from a Ni2 containing solution and nickel oxide films formed by anodic oxidation of a nickel substrate in very concentrated sulfuric acid. Chemical and crystallographic nature is analysed by in-situ Raman spectroscopy and the charge insertion mechanisms are studied by A.C. electrochemical impedance technique. The optical transfer function is also determined by means of 1254 Solartron frequency response analyzer. The complex capacitance C*(w), the differential coloration R/(RAE) and the differential coloration efficiency R/(RQ) are calculated.

  6. Technology assessment: observer study directly compares screen/film to CR mammography

    NASA Astrophysics Data System (ADS)

    Fletcher-Heath, Lynn; Richards, Anne; Ryan-Kron, Susan

    2007-03-01

    A new study supports and expands upon a previous reporting that computed radiography (CR) mammography offers as good, or better, image quality than state-of-the-art screen/film mammography. The suitability of CR mammography is explored through qualitative and quantitative study components: feature comparison and cancer detection rates of each modality. Images were collected from 150 normal and 50 biopsy-confirmed subjects representing a range of breast and pathology types. Comparison views were collected without releasing compression, using automatic exposure control on Kodak MIN-R films, followed by CR. Digital images were displayed as both softcopy (S/C) and hardcopy (H/C) for the feature comparison, and S/C for the cancer detection task. The qualitative assessment used preference scores from five board-certified radiologists obtained while viewing 100 screen/film-CR pairs from the cancer subjects for S/C and H/C CR output. Fifteen general image-quality features were rated, and up to 12 additional features were rated for each pair, based on the pathology present. Results demonstrate that CR is equivalent or preferred to conventional mammography for overall image quality (89% S/C, 95% H/C), image contrast (95% S/C, 98% H/C), sharpness (86% S/C, 93% H/C), and noise (94% S/C, 91% H/C). The quantitative objective was satisfied by asking 10 board-certified radiologists to provide a BI-RADS TM score and probability of malignancy per breast for each modality of the 200 cases. At least 28 days passed between observations of the same case. Average sensitivity and specificity was 0.89 and 0.82 for CR and 0.91 and 0.82 for screen/film, respectively.

  7. Study on the anticorrosion, biocompatibility, and osteoinductivity of tantalum decorated with tantalum oxide nanotube array films.

    PubMed

    Wang, Na; Li, Hongyi; Wang, Jinshu; Chen, Su; Ma, Yuanping; Zhang, Zhenting

    2012-09-26

    With its excellent anticorrosion and biocompatibility, tantalum, as a promising endosseous implant or implant coating, is attracting more and more attention. For improving physicochemical property and biocompatibility, the research of tantalum surface modification has increased. Tantalum oxide (Ta(2)O(5)) nanotube films can be produced on tantalum by controlling the conditions of anodization and annealing. The objective of our present study was to investigate the influence of Ta(2)O(5) nanotube films on pure tantalum properties related with anticorrosion, protein adsorption, and biological function of rabbit bone mesenchymal stem cells (rBMSCs). The polarization curve was measured, the adsorption of bovine serum albumin and fibronectin to Ta(2)O(5) nanotubes was detected, and the morphology and actin cytoskeletons of the rBMSCs were observed via fluorescence microscopy, and the adhesion and proliferation of the rBMSCs, as well as the osteogenic differentiation potential on tantalum specimens, were examined quantificationally by MTT and real-time PCR technology. The results showed that Ta(2)O(5) nanotube films have high anticorrosion capability and can increase the protein adsorption to tantalum and promote the adhesion, proliferation, and differentiation of rBMSCs, as well as the mRNA expression of osteogenic gene such as Osterix, ALP, Collagen-I, and Osteocalcin on tantalum. This study suggests that Ta(2)O(5) nanotube films can improve the anticorrosion, biocompatibility, and osteoinduction of pure tantalum, which provides the theoretical elaboration for development of tantalum endosseous implant or implant coating to a certain extent. PMID:22894817

  8. Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution

    NASA Astrophysics Data System (ADS)

    Sandoval-Paz, M. G.; Rodríguez, C. A.; Porcile-Saavedra, P. F.; Trejo-Cruz, C.

    2016-07-01

    Copper (I) selenide thin films with orthorhombic and cubic structure were deposited on glass substrates by using the chemical bath deposition technique. The effects of the solution pH on the films growth and subsequently the structural, optical and electrical properties of the films were studied. Films with orthorhombic structure were obtained from baths wherein both metal complex and hydroxide coexist; while films with cubic structure were obtained from baths where the metal hydroxide there is no present. The structural modifications are accompanied by changes in bandgap energy, morphology and electrical resistivity of the films.

  9. Thin Film?

    NASA Astrophysics Data System (ADS)

    Kariper, İ. Afşin

    2014-09-01

    This study focuses on the critical surface tension of lead sulfite (PbSO3) crystalline thin film produced with chemical bath deposition on substrates (commercial glass).The PbSO3 thin films were deposited at room temperature at different deposition times. The structural properties of the films were defined and examined according to X-ray diffraction (XRD) and the XRD results such as dislocation density, average grain size, and no. of crystallites per unit area. Atomic force microscopy was used to measure the film thickness and the surface properties. The critical surface tension of the PbSO3 thin films was measured with an optical tensiometer instrument and calculated using the Zisman method. The results indicated that the critical surface tension of films changed in accordance with the average grain size and film thickness. The film thickness increased with deposition time and was inversely correlated with surface tension. The average grain size increased according to deposition time and was inversely correlated with surface tension.

  10. Experimental study of Pulsed Laser Deposited Cu2ZnSnS 4 (CZTS) thin films for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Nandur, Abhishek S.

    Thin film solar cells are gaining momentum as a renewable energy source. Reduced material requirements (< 2 mum in total film thickness) coupled with fast, low-cost production processes make them an ideal alternative to Si (>15 mum in total thickness) solar cells. Among the various thin film solar absorbers that have been proposed, CZTS (Cu2ZnSnS4) has become the subject of intense interest because of its optimal band gap (1.45 eV), high absorption coefficient (104 cm--1 ) and abundant elemental components. Pulsed Laser Deposition (PLD) provides excellent control over film composition since films are deposited under high vacuum with excellent stoichiometry transfer from the target. Defect-free, near-stoichiometric poly-crystalline CZTS thin films were deposited using PLD from a stoichiometrically close CZTS target (Cu2.6Zn1.1Sn0.7S3.44). The effects of fabrication parameters such as laser energy density, deposition time, substrate temperature and sulfurization (annealing in sulfur) on the surface morphology, composition and optical absorption of the CZTS thin films were examined. The results show that the presence of secondary phases, present both in the bulk and on the surface, affected the electrical and optical properties of the CZTS thin films and the CZTS based TFSCs. After selectively etching away the secondary phases with DIW, HCl and KCN, it was observed that their removal improved the performance of CZTS based TFSCs. Optimal CZTS thin films exhibited an optical band gap of 1.54 eV with an absorption coefficient of 4x10 4cm-1 with a low volume of secondary phases. A TFSC fabricated with the best CZTS thin film obtained from the experimental study done in this thesis showed a conversion efficiency of 6.41% with Voc = 530 mV, Jsc= 27.5 mA/cm2 and a fill factor of 0.44.

  11. Study on the doping effect of Sn-doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Ajili, Mejda; Castagné, Michel; Turki, Najoua Kamoun

    2013-01-01

    Tin doped zinc oxide (ZnO:Sn) thin films were deposited onto Pyrex glass substrates by chemical spray pyrolysis technique starting from zinc acetate (CH3CO2)2Znṡ2H2O and tin chloride SnCl2. The effect of Sn doping on structural, optical and electrical properties was investigated. The atomic percentages of dopant in ZnO-based solution were y = [Sn4+]/[Zn2+] = 0%, 0.2%, 0.6% and 1%. It was found that all the thin films have a preferential c-axis orientation. With increase of Sn doping, the peak position of the (0 0 2) plane was shifted to the high 2θ values. ZnO:Sn demonstrated obviously improved surface roughness, reduced average crystallite size, enhanced Hall mobility and reduced resistivity. Among all of the tin doped zinc oxide in this study, films doped with 0.6 at.% Sn concentration exhibited the best properties, namely a Hall mobility of 9.22 cm2 V-1 s-1, an RMS roughness of 37.15 nm and a resistivity of 8.32 × 10-2 Ω cm.

  12. Fourier transform infrared studies of the interaction of HCl with model polar stratospheric cloud films

    NASA Technical Reports Server (NTRS)

    Koehler, Birgit G.; Mcneill, Laurie S.; Middlebrook, Ann M.; Tolbert, Margaret A.

    1993-01-01

    Heterogeneous reactions involving hydrochloric acid adsorbed on the surfaces of polar stratospheric clouds (PSCs) are postulated to contribute to polar ozone loss. Using FTIR spectroscopy to probe the condensed phase, we have examined the interaction of HCl with ice and nitric acid trihydrate (NAT) films representative of types II and I PSCs, respectively. For HCl pressures in the range of 10 exp -7 to 10 exp -5 Torr, our FTIR studies show that a small amount of crystalline HCl-6H2O formed on or in ice at 155 K. However, for higher HCl pressures, we observed that the entire film of ice rapidly converted into an amorphous 4:1 H2O:HCl mixture. From HCl-uptake experiments with P(HCl) = 8 x 10 exp -7 Torr, we estimate roughly that the diffusion coefficient of HCl in ice is around 2 x 10 exp -12 sq cm/s at 158 K. For higher temperatures more closely approximating those found in the stratosphere, we were unable to detect bulk HCl uptake by ice. Indirect evidence suggests that HCl adsorption onto the surface of model PSC films inhibited the evaporation of both ice and NAT by 3-5 K.

  13. Structural and electrical transport studies on CrN(001) thin films

    NASA Astrophysics Data System (ADS)

    Swamy, G. Venkat; Kumar, Dinesh; Rakshit, R. K.; Basheed, G. A.; Maurya, K. K.; Singh, Manju; Gupta, Anurag

    2016-05-01

    We report the structural and electrical transport studies on CrN1-x (CrN) thin films with varying of N2 flow (5 - 25 SCCM) in an Argon environment of 25 SCCM. CrN thin films were grown at 600°C, in a multi chamber vacuum system at working pressure of 1×10-2 Torr, under the base pressure of 1×10-7 Torr. Structural and electrical transport measurements were carried out using X-ray diffraction (XRD), atomic force microscopy (AFM) and SQUID magnetometer, respectively. XRD (θ-2θ, ω-2θ, and ω) patterns on CrN thin films revealed a structural phase transition which is associated with the lattice parameter variation from 4.136 to 4.168 Å. The temperature dependent resistivity measurements on CrN/MgO(001) showed a clear change in slope at ≈280 K which confirms the magneto-structural transition of CrN from paramagnetic rock salt face-centered-cubic (FCC) to antiferromagnetic orthorhombic structure.

  14. Artful terms: A study on aesthetic word usage for visual art versus film and music

    PubMed Central

    Augustin, M Dorothee; Carbon, Claus-Christian; Wagemans, Johan

    2012-01-01

    Despite the importance of the arts in human life, psychologists still know relatively little about what characterises their experience for the recipient. The current research approaches this problem by studying people's word usage in aesthetics, with a focus on three important art forms: visual art, film, and music. The starting point was a list of 77 words known to be useful to describe aesthetic impressions of visual art (Augustin et al 2012, Acta Psychologica 139 187–201). Focusing on ratings of likelihood of use, we examined to what extent word usage in aesthetic descriptions of visual art can be generalised to film and music. The results support the claim of an interplay of generality and specificity in aesthetic word usage. Terms with equal likelihood of use for all art forms included beautiful, wonderful, and terms denoting originality. Importantly, emotion-related words received higher ratings for film and music than for visual art. To our knowledge this is direct evidence that aesthetic experiences of visual art may be less affectively loaded than, for example, experiences of music. The results render important information about aesthetic word usage in the realm of the arts and may serve as a starting point to develop tailored measurement instruments for different art forms. PMID:23145287

  15. Artful terms: A study on aesthetic word usage for visual art versus film and music.

    PubMed

    Augustin, M Dorothee; Carbon, Claus-Christian; Wagemans, Johan

    2012-01-01

    Despite the importance of the arts in human life, psychologists still know relatively little about what characterises their experience for the recipient. The current research approaches this problem by studying people's word usage in aesthetics, with a focus on three important art forms: visual art, film, and music. The starting point was a list of 77 words known to be useful to describe aesthetic impressions of visual art (Augustin et al 2012, Acta Psychologica139 187-201). Focusing on ratings of likelihood of use, we examined to what extent word usage in aesthetic descriptions of visual art can be generalised to film and music. The results support the claim of an interplay of generality and specificity in aesthetic word usage. Terms with equal likelihood of use for all art forms included beautiful, wonderful, and terms denoting originality. Importantly, emotion-related words received higher ratings for film and music than for visual art. To our knowledge this is direct evidence that aesthetic experiences of visual art may be less affectively loaded than, for example, experiences of music. The results render important information about aesthetic word usage in the realm of the arts and may serve as a starting point to develop tailored measurement instruments for different art forms. PMID:23145287

  16. Fundamental studies of the mechanical behavior of microelectronic thin film materials

    NASA Astrophysics Data System (ADS)

    Nix, William D.

    1987-03-01

    A fundamental program of research on the mechanical properties of microelectronic thin film material has been initiated at Stanford University. The work is being supported under AFOSR Grant No. 86-0051. In this interim Scientific Report, some of the progress made during the first year of the program is reviewed. We have made very rapid progress,expecially in the development of new experimental techniques for measuring mechanical properties. The work has already led to several publications and to an equal number of invited oral presentations, both of which are listed at the end of this report. The primary motivation of this work is to understand the mechanical properties of microelectronic this film materials. Although these materials are not structural materials as such, they are, nevertheless, expected to withstand very high stresses, both during manufacturing and in service. As a consequence, the mechanical properties of these materials are almost as important as their electronic properties for successful device applicaitions. because these materials often exist only as thin films bonded to substrates, it is necessary to study their mechanical properties in that state.

  17. Electrostatic force microscopy studies of surface defects on GaAs/Ge films

    SciTech Connect

    Xu, Q.; Hsu, J.W.

    1999-03-01

    We apply electrostatic force microscopy (EFM) to study defects in GaAs films grown on Ge. On a GaAs film with surface antiphase boundaries (APBs), we reproducibly measure the surface contact potential (SCP) at the APBs to be (30{plus_minus}5) mV higher than that of the domains, due to the surface Fermi level at APBs being pinned closer to the valence band maximum. On a thick film which contains buried APBs and wedge-shaped depressions on the surface, we find that the SCP of the wedge-shaped depressions is (25{plus_minus}5) mV lower than that of the GaAs surface. Hence, these wedge-shaped depressions have defect electronic states different from those of APBs. The capacitance gradient ({partial_derivative}C/{partial_derivative}z) contrasts on the two samples are also shown to arise from different origins. Factors that can affect the measured SCP and {partial_derivative}C/{partial_derivative}z values are discussed. We demonstrate a new application of EFM to distinguish different types of defects by measuring variations in relative SCP (thus the work function or position of Fermi level) and/or {partial_derivative}C/{partial_derivative}z on sample surfaces. The spatial resolutions of SCP and {partial_derivative}C/{partial_derivative}z are 30 nm, limited by the tip size. {copyright} {ital 1999 American Institute of Physics.}

  18. Study of Dy-doped Bi2Te3: thin film growth and magnetic properties

    NASA Astrophysics Data System (ADS)

    Harrison, S. E.; Collins-McIntyre, L. J.; Zhang, S.-L.; Baker, A. A.; Figueroa, A. I.; Kellock, A. J.; Pushp, A.; Parkin, S. S. P.; Harris, J. S.; van der Laan, G.; Hesjedal, T.

    2015-06-01

    Breaking the time-reversal symmetry (TRS) in topological insulators (TIs) through ferromagnetic doping is an essential prerequisite for unlocking novel physical phenomena and exploring potential device applications. Here, we report the successful growth of high-quality (DyxBi1-x)2Te3 thin films with Dy concentrations up to x = 0.355 by molecular beam epitaxy. Bulk-sensitive magnetisation studies using superconducting quantum interference device magnetometry find paramagnetic behaviour down to 2 K for the entire doping series. The effective magnetic moment, μeff, is strongly doping concentration-dependent and reduces from ˜12.6 μB Dy-1 for x = 0.023 to ˜4.3 μB Dy-1 for x = 0.355. X-ray absorption spectra and x-ray magnetic circular dichroism (XMCD) at the Dy M4,5 edge are employed to provide a deeper insight into the magnetic nature of the Dy3+-doped films. XMCD, measured in surface-sensitive total-electron-yield detection, gives μeff = 4.2 μB Dy-1. The large measured moments make Dy-doped films interesting TI systems in which the TRS may be broken via the proximity effect due to an adjacent ferromagnetic insulator.

  19. AFM and STM studies of the carbonization and graphitization of polyimide films

    NASA Astrophysics Data System (ADS)

    Nysten, B.; Roux, J.-C.; Flandrois, S.; Daulan, C.; Saadaoui, H.

    1993-11-01

    Kapton polyimide and high-modulus polyimide (PPT) films were carbonized and graphitized at various temperatures from 600 to 3000 °C. Their surface was studied by atomic-force microscopy and/or by scanning tunneling microscopy in order to follow the modification of the large-scale morphology and the atomic structure as a function of the heat-treatment temperature (HTT). On the pristine Kapton films, the local order of the molecules is brought to the fore. With increasing HTT (600 to 1000 °C) the structure becomes more disordered while at larger scale a bumpy morphology appears. During graphitization, the bumpy morphology gradually disappears and is replaced by graphitized terraces whose size increases with HTT. At atomic scale, it is shown that the graphene layers progressively grow for HTT higher than 1800 °C. On the films treated between 1800 and 2400 °C, graphene layers containing point defects are imaged and (√3 × √3 )R 30° superstructures are observed near large defects. On the samples treated at 2400 and 2600 °C, moiré patterns are observed and are attributed to stacking faults (turbostratic structure).

  20. Using nanoscale amorphous solid water films to create and study deeply supercooled liquid water at interfaces

    NASA Astrophysics Data System (ADS)

    Kay, Bruce

    Molecular beam vapor deposition of water on cryogenic substrates is known to produce amorphous solid films. When heated above their glass transition these films transform into deeply supercooled liquid water. These nanoscale liquid films can be used to study kinetic processes such as diffusion, isotope exchange, crystallization, and solvent mediated reactions in unprecedented detail. This talk will highlight our recent advances in this area. My colleagues Yuntao Xu, Chunqing Yuan, Collin Dibble, R. Scott Smith, Nick Petrik, and Greg Kimmel made important contributions to this work.This work was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The research was performed using EMSL, a national scientific user facility sponsored by DOE's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory, which is operated by Battelle, operated for the U.S. DOE under Contract DE-AC05-76RL01830.

  1. Comparative study of the corrosion product films formed in biotic and abiotic media

    SciTech Connect

    Videla, H.A.; Mele, M.F.L. de; Swords, C.; Edyvean, R.G.J.; Beech, I.B.

    1999-11-01

    The growth of sulfate-reducing bacteria (SRB) affects several important parameters at the metal/solution interface of carbon steel in liquid media such as pH and redox potential values, as well as modifications of the composition and structure of corrosion product layers. Electrochemical techniques for corrosion assessment and surface analyses by energy dispersion X-ray analysis (EDAX), X-ray photoelectron spectra (XPS), X-ray distraction (XRD) and electron microprobe analysis (EPMA) complemented with scanning electron microscopy (SEM) and atomic force microscopy (MM) observations, were used to study the structure and composition of protective films on carbon steel in abiotic and biotic media containing different sulfur anions. The results revealed that in biotic and abiotic sulfide films the outer layers were formed by both FeS and FeS{sub 2}, although the relative content of these compounds varied in each case. Usually, the corrosion product films biotically formed were more adherent to the metal surface than those developed abiotically. The latter were flaky and loosely adherent, thus differing in their function during the corrosion process.

  2. Study on flavonoid migration from active low-density polyethylene film into aqueous food simulants.

    PubMed

    Zhang, Shuangling; Zhao, Haiyan

    2014-08-15

    The migration of flavonoids from low-density polyethylene (LDPE) film (0.4%, w/w) to aqueous food simulants over 16 weeks at 0, 15, and 30 °C was investigated. The migration amount of total flavonoids was calculated based on the rutin contents determined by high-performance liquid chromatography (HPLC). Diffusion and partition coefficients, along with the activation energy (Ea) were calculated based on Fick's second law. The results showed that the migration of flavonoids was influenced by temperature, time and the simulants. The Ea values for flavonoid diffusion were 49.2, 55.9, and 25.8 kJ mol(-1) in distilled water, 4% acetic acid and 30% ethanol, respectively. This study indicated that the flavonoids in LDPE film easily migrated into food simulants; and this behaviour was related to the low Ea values of flavonoid diffusion, especially in ethanol at 0-30 °C, when the antioxidants were released from the film. PMID:24679750

  3. Thickness effect on magnetocrystalline anisotropy of Co/Pd(111) films: A density functional study

    SciTech Connect

    Jekal, Soyoung; Rhim, S. H. E-mail: schong@ulsan.ac.kr; Kwon, Oryong; Hong, Soon Cheol E-mail: schong@ulsan.ac.kr

    2015-05-07

    In this study, we carried out first-principles calculations on magnetocrystalline anisotropy (MCA) of Co/Pd thin films by adopting two different systems of (i) n-Co/3-Pd and (ii) n-Pd/3-Co. In one system, we vary the thickness of Co layer, fixing the thickness of the Pd layer to 3-monolayers, and in the other system vice versa. MCA is mainly governed by the surface and interface Co atoms, while contributions from other Co atoms are smaller. MCA energy (E{sub MCA}) of the Co/Pd thin film shows oscillatory behavior with the thickness of the Co layer, but is insensitive to the thickness of the Pd layer. In particular, the n-Co/3-Pd films of n = 2, 4, and 6 exhibit strong perpendicular MCA of about 1 meV. Our results suggest that controlling the thickness of the Co layer in Co/Pd (111) is crucial in achieving strong perpendicular MCA.

  4. Temperature dependent dielectric and ferroelectric studies of BiFeO3 thin film

    NASA Astrophysics Data System (ADS)

    Gaur, Anand P. S.; Barik, Sujit K.; Katiyar, Ram S.

    2013-03-01

    Although BiFeO3 (BFO) has received a lot of interest due to its good multiferroic properties at room temperature, high leakage current limit its usage for practical applications. Recently, it is found that these properties in thin films can be different due to strain effect induced by substrate, preparation conditions and electrode effects, etc. In this context, we have studied the temperature dependence of polarization and dielectric properties of BFO thin film by varying the bottom electrode thickness and using different electrodes. The strain dependent ferroelectric switching behaviors have also been investigated with a traditional ferroelectric tester and switching spectroscopy piezoresponse force microscopy (SS-PFM), respectively. We used pulsed laser deposition to fabricate thin films of BFO using Si (100) substrate and SrTiO3(STO) as buffer layer with different bottom electrodes such as SrRuO3(SRO), LaNiO3(LNO) and Pt/Si. The thickness of STO layer is kept fixed around 70 nm and the thicknesses of BFO and electrode layer were varied from 70 nm to 200nm. The layers were grown under optimized conditions and polycrystalline nature is found from room temperature XRD. A large enhancement of polarization is found while using LNO electrode and also with reducing the thickness of BFO layer. The remnant polarization and cohesivity also shows large increase with increaisng temperature, although leakage current increases significantly. NSF

  5. Fabrication and kinetics study of nano-Al/NiO thermite film by electrophoretic deposition.

    PubMed

    Zhang, Daixiong; Li, Xueming

    2015-05-21

    Nano-Al/NiO thermites were successfully prepared as film by electrophoretic deposition (EPD). For the key issue of this EPD, a mixture solvent of ethanol-acetylacetone (1:1 in volume) containing 0.00025 M nitric acid was proved to be a suitable dispersion system for EPD. The kinetics of electrophoretic deposition for both nano-Al and nano-NiO were investigated; the linear relation between deposition weight and deposition time in short time and parabolic relation in prolonged time were observed in both EPDs. The critical transition time between linear deposition kinetics and parabolic deposition kinetics for nano-Al and nano-NiO were 20 and 10 min, respectively. The theoretical calculation of the kinetics of electrophoretic deposition revealed that the equivalence ratio of nano-Al/NiO thermites film would be affected by the behavior of electrophoretic deposition for nano-Al and nano-NiO. The equivalence ratio remained steady when the linear deposition kinetics dominated for both nano-Al and nano-NiO. The equivalence ratio would change with deposition time when deposition kinetics for nano-NiO changed into parabolic kinetics dominated after 10 min. Therefore, the rule was suggested to be suitable for other EPD of bicomposites. We also studied thermodynamic properties of electrophoretic nano-Al/NiO thermites film as well as combustion performance. PMID:25950271

  6. Microstructure and cathodoluminescence study of sprayed Al and Sn doped ZnS thin films

    NASA Astrophysics Data System (ADS)

    El Hichou, A.; Addou, M.; Bubendorff, J. L.; Ebothé, J.; El Idrissi, B.; Troyon, M.

    2004-02-01

    Here we report on the study of ZnS and X-doped ZnS (with 4 at% of X = Al, Sn) thin films, prepared by spray pyrolysis technique using chloride precursors. Cathodoluminescence imaging and spectroscopy, x-ray diffraction, x-ray energy dispersive spectrometry and spectrophotometry have been used for their characterization. Deposited at their optimal substrate temperature (Ts = 773 K), these films are polycrystalline and consist of mixed hexagonal (agr) and cubic (bgr) phases with a predominance of the cubic phase. Their growth is preferentially oriented along the (111)bgr direction and their optical bandgap always remains close to 3.56 eV regardless of the sample considered. The cathodoluminescence spectra of ZnS and Al-ZnS films are similar and are characterized by a blue emission peak at 407 nm (3.05 eV) and a broad blue-green one located at 524 nm (2.36 eV) due to the presence of chlorine. The insertion of Sn2+ ions in the ZnS material leads to the formation of the SnCl2 compound and to the disappearance of the blue-green emission associated with Cl ionized donors.

  7. Temperature-dependent photoluminescence studies of GdTiO3 thin films

    NASA Astrophysics Data System (ADS)

    Verma, Amit; Raghavan, Santosh; Protasenko, Vladimir; Stemmer, Susanne; Jena, Debdeep

    2013-03-01

    GdTiO3 (GTO), a Mott-insulator, has acquired increased prominence in last few years since the discovery of a 2-dimensional electron gas (2DEG) at its heterojunction with the band-insulator SrTiO3. These 2DEGs have very large electron densities (~3x1014 cm-2) amounting to half electron per unit cell. To realize many possible applications of this large 2DEG, an understanding of the GTO bandstructure is needed. With this goal in mind, in this work we present photoluminescence (PL) studies of GTO thin films (10nm and 20nm) grown by molecular beam epitaxy (MBE) on (001) LSAT substrates. When pumped with a 325 nm He-Cd laser, we observe a red PL (~683 nm at 300K) from both GTO thin films at RT. Upon lowering the temperature from 300K to 80K, the PL peak blue shifts by ~0.14eV. Interestingly, the reported activation energy of the resistivity of MBE-grown GTO thin films is also ~0.14eV (Moetakef et al., J. Crystal Growth 355, 166 (2012)). We connect the observed temperature-dependent PL data with the expected electronic bandstructure and electrical resistivity, and explain the sharp transition in the peak that occurs between 120K-200K from ~636nm to ~683nm. Office of Naval Research through grant number (N00014-12-1-0976).

  8. Experimental and Theoretical X-Ray Absorption Studies of Strain Effects in Films

    NASA Astrophysics Data System (ADS)

    Tyson, Trevor A.; Qian, Qing; Kao, Chi-Chang; Prellier, Wilfred

    2000-03-01

    From the pioneering work of Jin et al. [1], is was realized that the magnetoresistance of CMR films exhibits a strong thickness dependence. Recent theoretical work by Millis et al.[2], revealed that the Curie temperature of manganites is extremely sensitive to biaxial strain. The atomic details of the correlations between strain and magnetic properties present an area which has not been thoroughly explored. We find that the Mn K-Edge x-ray absorption near edge spectra (XANES) are strongly modified by local structural distortions such as Jahn-Teller (JT) distortions. We find that the measured asymmetry (JT induced) in the polarized XANES of Nd_0.5Sr_0.5MnO3 films correlates with the transition from charge ordering to metallic behavior [3]. Combined experimental and theoretical XANES and XAFS studies can be used to identify the structural phases present in films as a function of thickness. This work is supported by National Science Foundation Career Grant DMR-9733862 and by DOE Grant DE-FG02-97ER45665. [1] S. Jin et al., Appl. Phys. Lett. 67, 557 (1995)., [2] A. J. Millis et al., J. Appl. Phys. 83, 1588 (1998), [3] W. Prellier et al., Appl. Phys. Lett. 75, 397 (1999).

  9. The study of tribological performance and surface film characterization of bismuth dioctyldithiocarbamate

    SciTech Connect

    Chen Ligong; Dong Junxiu; Chen Guoxu

    1997-05-01

    In this study, bismuth dioctyldithiocarbamate has been synthesized, and its tribological behaviors, such as friction-reducing ability, antiwear property and extreme pressure performance have been respectively evaluated with a ring-on-block test rig and a fourball machine. In addition to correlate its tribological behaviors with the film formed on the metallic rubbing surface under boundary lubrication conditions, surface analyses have been conducted to characterize the surface film by means of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and energy dispersion of X-ray (EDX). Test results show the additive compound can effectively improve the friction and wear of the rubbing couples. On the other hand, EDX confirmed the presence of carbon, oxygen, sulfur, nitrogen, bismuth and iron on the surface; AES revealed their depth distribution of atomic concentration percentages. Whereas XPS further disclosed that the composition of the surface film was composed of organic and inorganic species including iron sulfide and sulfate, metallic bismuth, bismuth oxide and sulfide, etc. which are conducive to the reduction of friction and wear.

  10. Study on Wear Reduction Mechanisms of Artificial Cartilage by Synergistic Protein Boundary Film Formation

    NASA Astrophysics Data System (ADS)

    Nakashima, Kazuhiro; Sawae, Yoshinori; Murakami, Teruo

    Poly(vinyl alcohol) (PVA) hydrogel is one of the anticipated materials for artificial cartilage. PVA hydrogel has high water content and a low elastic modulus similar to natural cartilage, but its major disadvantage is its lower strength. PVA hydrogel experienced rapid wear under severe conditions such as mixed or boundary lubrication. Therefore, the existence of a protective surface film with low friction becomes important to prevent surface failure. In this study, the reciprocating frictional tests for a sliding pair of PVA hydrogel and glass plate were carried out, and fluorescent observations were performed to identify the roles of adsorbed protein film. Albumin and γ-globulin, which are contained in natural synovial fluid, were used by mixing into the lubricant. It appears that groups of albumin molecules adsorb on the smooth γ-globulin adsorbed layer at content of 2.1wt% of proteins with an appropriate ratio. But in the case of a lubricant which has excessive protein at 2.8wt%, albumin and γ-globulin adsorbed separately. Considering the wear reduction at 2.1wt% content of protein, albumin and γ-globulin constituted synergistic adsorbed film for wear reduction. It is indicated that albumin constructs a low shear layer and γ-globulin forms a layer protecting PVA hydrogel from wear. It is considered that wear and friction of PVA hydrogel were reduced due to slip of the boundary of adsorbed albumin and γ-globulin layer. Content of protein and ratio of albumin to γ-globulin (AG ratio) are important to constitute the appropriate protein film.

  11. Toward efficient electrochromic NiO{sub x} films: A study of microstructure, morphology, and stoichiometry of radio frequency sputtered films

    SciTech Connect

    Faria, I.C.; Kleinke, M.; Gorenstein, A.

    1998-01-01

    In this work, NiO{sub x} films were deposited by reactive radio frequency sputtering, varying either the oxygen flow or the power during deposition. The morphology was studied by atomic force microscopy. The Ni/O and Ni/H ratios were determined by Rutherford backscattering spectroscopy and forward recoil spectroscopy. The microstructure of pristine and colored or bleached films were investigated by means of X-ray diffraction. The electrochromic and mechanical behavior in aqueous alkaline electrolyte were investigated in situ. Samples deposited at low oxygen flow (or high power) are transparent, and have the highest Ni/O ratio and the lowest Ni/H ratio. The effective area is also greater for these samples. Samples deposited t high oxygen flow (or low power) are dark brown and present the lowest Ni/O ratio and the highest Ni/H ratio. For all samples, the Ni/O ratio is lower than 1. All films were cubic NiO, with preferred orientation in the (111) direction. Lattice parameters and crystalline grain size increase with the increase of oxygen flow (or decrease of power) during deposition. The highest optical contrast and lowest stress changes upon intercalation were obtained for samples deposited at low oxygen flow. Nonintentional, low-size dopants, like H, favor the mechanical stability of the films.

  12. Study of Surface Cleaning Methods and Pyrolysis Temperature on Nano-Structured Carbon Films using X-ray Photoelectron Spectroscopy

    SciTech Connect

    Kerber, Pranita B.; Porter, Lisa M.; McCullough, L. A.; Kowalewski, Tomasz; Engelhard, Mark H.; Baer, Donald R.

    2012-10-12

    Nanostructured carbon (ns-C) films fabricated by stabilization and pyrolysis of di-block copolymers are of interest for a variety of electrical/electronic applications due to their chemical inertness, high-temperature insensitivity, very high surface area, and tunable electrical resistivity over a wide range [Kulkarni et al., Synth. Met. 159, (2009) 177]. Because of their high porosity and associated high specific surface area, controlled surface cleaning studies are important for fabricating electronic devices from these films. In this study, quantification of surface composition and surface cleaning studies on ns-C films synthesized by carbonization of di-block copolymers of polyacrylonitrile-b-poly(n-butyl acrylate) (PAN-b-PBA) at two different temperatures were carried out. X-ray photoelectron spectroscopy was used for elemental analysis and to determine the efficacy of various surface cleaning methods for ns-C films and to examine the polymer residues in the films. The in-situ surface cleaning methods included: HF vapor treatment, vacuum annealing, and exposure to UV-ozone. Quantitative analysis of high-resolution XPS scans showed 11 at. % of nitrogen present in the films pyrolyzed at 600 °C, suggesting incomplete denitrogenation of the copolymer films. The nitrogen atomic concentration reduced significantly for films pyrolyzed at 900 °C confirming extensive denitrogenation at that temperature. Furthermore, quantitative analysis of nitrogen sub-peaks indicated higher loss of nitrogen atoms residing at the edge of graphitic clusters relative to that of nitrogen atoms within the graphitic cluster, suggesting higher graphitization with increasing pyrolysis temperature. Of the surface cleaning methods investigated, in-situ annealing of the films at 300 °C for 40 min was found to be the most efficacious in removing adventitious carbon and oxygen impurities from the surface.

  13. Study of surface cleaning methods and pyrolysis temperatures on nanostructured carbon films using x-ray photoelectron spectroscopy

    SciTech Connect

    Kerber, Pranita; Porter, Lisa M.; McCullough, Lynne A.; Kowalewski, Tomasz; Engelhard, Mark; Baer, Donald

    2012-11-15

    Nanostructured carbon (ns-C) films fabricated by stabilization and pyrolysis of diblock copolymers are of interest for a variety of electrical/electronic applications due to their chemical inertness, high-temperature insensitivity, very high surface area, and tunable electrical resistivity over a wide range [Kulkarni et al., Synth. Met. 159, 177 (2009)]. Because of their high porosity and associated high specific surface area, controlled surface cleaning studies are important for fabricating electronic devices from these films. In this study, quantification of surface composition and surface cleaning studies on ns-C films synthesized by carbonization of diblock copolymers of polyacrylonitrile-b-poly(n-butyl acrylate) at two different temperatures were carried out. X-ray photoelectron spectroscopy was used for elemental analysis and to determine the efficacy of various surface cleaning methods for ns-C films and to examine the polymer residues in the films. The in-situ surface cleaning methods included HF vapor treatment, vacuum annealing, and exposure to UV-ozone. Quantitative analysis of high-resolution XPS scans showed 11 at. % nitrogen was present in the films pyrolyzed at 600 Degree-Sign C, suggesting incomplete denitrogenation of the copolymer films. The nitrogen atomic concentration decreased significantly for films pyrolyzed at 900 Degree-Sign C confirming extensive denitrogenation at that temperature. Furthermore, quantitative analysis of nitrogen subpeaks indicated higher loss of nitrogen atoms residing at the edge of graphitic clusters relative to that of nitrogen atoms within the graphitic clusters, suggesting higher graphitization with increasing pyrolysis temperature. Of the surface cleaning methods investigated, in-situ annealing of the films at 300 Degree-Sign C for 40 min was found to be the most efficacious in removing adventitious carbon and oxygen impurities from the surface.

  14. An XPD and LEED study of highly strained ultrathin Ni films on Pd(1 0 0)

    NASA Astrophysics Data System (ADS)

    Petukhov, M.; Rizzi, G. A.; Sambi, M.; Granozzi, G.

    2003-05-01

    The epitaxial growth of ultrathin Ni films on the Pd(1 0 0) surface was studied by means of X-ray photoelectron diffraction (XPD) and LEED experiments. In excellent numerical agreement with the predictions of elasticity theory, the data indicate the formation of tetragonally strained Ni epitaxial layers, which subsequently turns into a bulk-like Ni structure as the thickness of approximately 12 MLE is exceeded. This study demonstrates that LEED and XPD methodologies are rather complementary in order to have a detailed picture of the evolution of the overlayer structure in different thickness regimes.

  15. UPS study of VUV-photodegradation of polytetrafluoroethylene (PTFE) ultrathin film by using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Ono, Masaki; Yamane, Hiroyuki; Fukagawa, Hirohiko; Kera, Satoshi; Yoshimura, Daisuke; Okudaira, Koji K.; Morikawa, Eizi; Seki, Kazuhiko; Ueno, Nobuo

    2005-07-01

    The VUV-photodegradation of polytetrafluoroethylene (PTFE) ultra-thin film was studied by ultraviolet photoelectron spectroscopy and quadrupole mass spectrometry. These results were compared with the previous photodegradation studies of the polyvinylidenefluoride (PVDF) and polyethylene (PE). Generation of new peak, π-band originated from the Cdbnd C bond, was observed in the low binding energy region of the UPS spectra in both PVDF and PE during the photodegradation. In contrast, no new peak generation was observed in the UPS of the photodegraded PTFE. Mass spectrometry analysis also suggested that the Cdbnd C bond generation is not a major mechanism in the VUV photodegradation of PTFE.

  16. Structural and thermal studies of silver nanoparticles and electrical transport study of their thin films

    PubMed Central

    2011-01-01

    This work reports the preparation and characterization of silver nanoparticles synthesized through wet chemical solution method and of silver films deposited by dip-coating method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and energy dispersive spectroscopy (EDX) have been used to characterize the prepared silver nanoparticles and thin film. The morphology and crystal structure of silver nanoparticles have been determined by FESEM, HRTEM, and FETEM. The average grain size of silver nanoparticles is found to be 17.5 nm. The peaks in XRD pattern are in good agreement with that of face-centered-cubic form of metallic silver. TGA/DTA results confirmed the weight loss and the exothermic reaction due to desorption of chemisorbed water. The temperature dependence of resistivity of silver thin film, determined in the temperature range of 100-300 K, exhibit semiconducting behavior of the sample. The sample shows the activated variable range hopping in the localized states near the Fermi level. PMID:21711498

  17. Spectroscopic studies of regio-regular and regio-random polythiophene films

    NASA Astrophysics Data System (ADS)

    Valy Vardeny, Z.

    2002-03-01

    Poly(3 hexyl thiophene) [P3HT] can be synthesized with regio-regular (RR-) order in which the side groups are arranged head to tail, and regio-random (RRa-) order in which the side groups are not arranged in a particular form. It has been recently discovered that films cast from RR-P3HT form two-dimensional (2D) lamellae perpendicular to the substrate, whereas RRa-P3HT forms lamellae to a lesser extend [1,2]. The interchain interplane separation in the lamellae is of order 4 Angstr. causing a strong interchain interaction. This has a profound influence on the charged and neutral photoexcitations in RR-P3HT films compared to those of RRa-P3HT. We have employed a variety of steady state and ps transient spectroscopies to study and compare the photoexcitations in RR- and RRa- P3HT films. In the ps time domain we found [3] in RRa-P3HT films that intrachain excitons with correlated photoinduced absorption (PA) and stimulated emission (SE) bands are the primary excitations; they give rise to a moderately strong photoluminescence (PL) band. In RR-P3HT films, on the contrary the primary excitations are excitons with a much larger interchain component; this results in lack of a SE band, vanishing small intersystem crossing and very weak PL band [3]. We also measured in RR-P3HT films photogenerated polaron pairs with ultrafast dynamics that are precursor to long-lived polaron excitations. In the steady state we measured long-lived polaron excitations in both RR- and RRa- P3HT films, however with different relaxation energies [2]. Whereas the polaron relaxation energy in RRa-P3HT is of the order of 0.5 eV, it is only about 50 meV in RR-P3HT. This shows that the polarons are delocalized in the 2D lamellae, consistent with the carrier relative high mobility [1] and superconductivity [4] found in RR-P3HT films. As a result of the very low relaxation energy in RR-P3HT we found that the polaron optical transition in the mid ir spectral range overlaps with several photoinduced ir

  18. Study of the physics of insulating films as related to the reliability of metal-oxide semiconductor devices

    NASA Astrophysics Data System (ADS)

    Young, D. R.; Dimaria, D. J.

    1983-08-01

    The papers enclosed with this report include: a new method for studying hot electron energy distributions in SiO2, plasma enhanced chemical vapor deposition of Si-rich SiO2, the use of Si-rich SiO2 to greatly reduce electron trapping effects, the use of Si-rich SiO2 to increase the yield of thin film capacitors, ellipsometry measurements of polycrystalline silicon films and the use of a delay time technique to measure the diffusion of the oxidant in SiO2 films.

  19. Studies on the properties of Al2O3:Cr2O3 (50:50) thin film

    NASA Astrophysics Data System (ADS)

    Ponmudi, S.; Sivakumar, R.; Sanjeeviraja, C.

    2016-05-01

    Aluminium oxide (Al2O3) and chromium oxide (Cr2O3) thin films have received great attention of researchers because of their unique properties of corrosion/oxidation resistance and high dielectric constant. In addition, chromium aluminium oxide has been considered as a best candidate for deep-ultraviolet optical masks. In the present work, thin films of Al2O3:Cr2O3 (50:50) were deposited on pre-cleaned microscopic glass substrate by RF magnetron sputtering technique. The substrate temperature and RF power induced changes in structural, surface morphological, compositional and optical properties of the films have been studied.

  20. Morphological origin for the stratification of P3HT:PCBM blend film studied by neutron reflectometry

    SciTech Connect

    Keum, Jong Kahk; Center for Nanophase Material Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 ; Browning, James F.; Halbert, Candice E.; Xiao, Kai; Shao, Ming; Hong, Kunlun

    2013-11-25

    Understanding the origin for the film stratification of electron donor/acceptor blend is crucial for high efficiency organic photovoltaic cell. In this study, P3HT:PCBM blend is deposited onto hydrophilic and hydrophobic substrate to examine the film stratifications. The neutron reflectivity results show that, on the different surfaces, PCBM diffuses toward the two interfacial regions in an identical fashion during thermal annealing. This evidences that the film stratification is not affected by the substrates. Instead, since P3HT remains more amorphous in the interfacial regions and PCBM is miscible with amorphous P3HT, PCBM preferentially diffuses to the interfacial regions, resulting in the stratification.

  1. Structural study of TiO{sub 2}-based transparent conducting films

    SciTech Connect

    Hitosugi, T.; Yamada, N.; Nakao, S.; Hatabayashi, K.; Shimada, T.; Hasegawa, T.

    2008-07-15

    We have investigated microscopic structures of sputter and pulsed laser deposited (PLD) anatase Nb-doped TiO{sub 2} transparent conducting films, and discuss what causes the degradation of resistivity in sputter-deposited films. Cross-sectional transmission electron microscope and polarized optical microscope images show inhomogeneous intragrain structures and small grains of {approx}10 {mu}m in sputter-deposited films. From comparison with PLD films, these results suggest that homogeneous film growth is the important factor to obtain highly conducting sputter-deposited film.

  2. A study of the thin film battery electrolyte lithium phosphorus oxynitride deposited by an ion beam assisted process

    NASA Astrophysics Data System (ADS)

    Vereda-Moratilla, Fernando

    Thin film Li-ion batteries are currently the subject of a world-wide research effort because of their many potential applications as portable energy sources. One of the key elements of these batteries is the electrolyte. Since it was first produced in the early 1990's, the preferred solid state thin film Li-ion electrolyte is lithium phosphorus oxynitride (LiPON), which is normally grown by means of reactive rf sputtering of a Li3PO 4 target in an N2 atmosphere. Solid electrolytes such as LiPON have several advantages compared to the liquid electrolytes normally used in bulk batteries. Solid electrolytes avoid leakage and have excellent charge-discharge cycling properties. Furthermore, sputtered-deposited LiPON proved to be stable versus Li+/Li from 0 to +5.5 V, which exceeded the stability window of any of the liquid electrolytes. In this work we present a general study of the properties of LiPON thin films deposited by an alternative process: ion beam assisted deposition (IBAD). In this process Li3PO4 is vacuum thermally evaporated and the condensing film is simultaneously bombarded with nitrogen ions which incorporate to form LiPON. Because of its application as an electrolyte and because of a previous study in which we showed that tensile stress led to cracking of the LiPON films and subsequently to shorting of the battery devices, the emphasis of the study was placed on improving the electrochemical properties of the films and on reducing their residual stress. Additional effort was aimed at learning about the structure and the composition of our films. It has been shown that IBAD LiPON thin films are undoubtedly capable of high quality performance as the electrolyte in Li-ion thin film batteries. Their ionic conductivity is almost as high, and their electronic conductivity as low, as those of the sputtered films. Their major advantages when compared to sputtered LiPON films are: (i) a higher deposition rate; (ii) a lower concentration of reduced-phosphorus in

  3. Studying gas-sheared liquid film in horizontal rectangular duct with LIF technique: droplets deposition and bubbles entrapment

    NASA Astrophysics Data System (ADS)

    Cherdantsev, Andrey; Hann, David; Azzopardi, Barry

    2014-11-01

    High-speed laser-induced fluorescence technique is applied to study gas-sheared liquid film in horizontal rectangular duct (width 161 mm). Instantaneous distributions of film thickness over an area of 50*20 mm are obtained with frequency 10 kHz and spatial resolution 40 μm. The technique is also able to detect droplets entrained from film surface and gas bubbles entrapped by the liquid film. We focus on deposition of droplets onto film surface and dynamics of bubbles. Three scenarios of droplet impact are observed: 1) formation of a cavern, which is similar to well-known process of normal droplet impact onto still liquid surface; 2) ``ploughing,'' when droplet is sinking over long distance; 3) ``bouncing,'' when droplet survives the impact. The first scenario is often accompanied by entrainment of secondary droplets; the second by entrapment of air bubbles. Numerous impact events are quantitatively analyzed. Parameters of the impacting droplet, the film surface before the impact, the evolution of surface perturbation due to impact and the outcome of the impact (droplets or bubbles) are measured. Space-time trajectories of individual bubbles have also been obtained, including velocity, size and concentration inside the disturbance waves and in the base film region. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  4. A Short Study Film for Teaching the Solution of Simple Problems in Multiplication Using the C and D Scales of the Slide Rule.

    ERIC Educational Resources Information Center

    Beamish, Eric Edward

    This project was designed to plan a short study self-instructional film for teaching the use of the C and D scales of the slide rule in solving simple problems in multiplication and to produce one of these films. The film was designed to exploit the unique presentational features of a cartridge loading projector equipped with automatic stop and…

  5. Raman and photoluminescence studies of poly (p-phenylene sulfide) films

    SciTech Connect

    Pan, Z.

    1992-01-01

    Scope and method of study. Micro-Raman and photoluminescence (PL) measurements have been performed on various poly (p-phenylene sulfide) (PPS) films to investigate the morphology and emission properties of this important polymer material. A cw argon laser at 514.5 nm was used in the Raman study while a pulsed Nd:YAG laser at 355 nm was used in the PL study. A phenylene-sulfur stretching vibration model was proposed to interpret the influence of polymer crystallinity on the Raman spectrum and to calculate the effective force constant. A lattice relaxation model was developed to explain the vibronic structure in the PL spectrum and the electron-phonon coupling in PPS. Findings and conclusions: It was found that: (i) the intensity, and the line profile of the main Raman band at 1076 cm[sup [minus]1] were related to the crystallinity of the PPS film; (ii) the effective stretching and bending force constants between the phenylene ring and the sulfur atom were determined; (iii) new Raman lines at 840 and 919 cm[sup [minus]1] were observed and assigned to the out of plane C-H bending modes; (iv) the vibronic structure with energy spacing equal to the phenylene-sulfur stretching mode was observed in low temperature PL spectrum of all PPS samples, which provided evidence that the electronic transition was coupled to the intrachain stretching in PPS; (V) the electron-phonon coupling strength and the temporary lattice distortion were determined for the unaged and aged films. The coupling strength was reduced in the aged sample possibly due to the increased [pi]-orbital overlap caused by the crosslinking which resulted from the thermal-aging process.

  6. Bioequivalence study of 8 mg ondansetron film-coated tablets in healthy Caucasian volunteers.

    PubMed

    Rudzki, P J; Kaza, M; Leś, A; Gilant, E; Ksycińska, H; Serafin-Byczak, K; Troć, M; Raszek, J; Piątkowska-Chabuda, E; Skowrońska-Smolak, M; Tarasiuk, A; Wilkowska, E; Łazowski, T

    2014-04-01

    The aim of the study was to investigate the bioequivalence of a generic product of 8 mg film-coated tablets (test) to the branded product (reference) at the same strength in order to apply for regulatory approval. The secondary objective of the study was to compare the tolerability of both products. A double blinded, randomized, cross-over, 2-period, comparative study was conducted in healthy Caucasian volunteers under fasting conditions. A single oral dose administration of the test or reference product was followed by a 7-day wash-out period. The ondansetron concentration was determined using a validated high performance liquid chromatography with a UV detection method. The 90% confidence interval of the point estimate (test over reference products) for C(max) and AUC(0-t) fell within the 80.00-125.00% acceptance range. The results of the study indicate that the film-coated tablets of Ondatron 8 mg manufactured by Tarchomińskie Zakłady Farmaceutyczne Polfa S.A. (test product) are bioequivalent to those of Zofran manufactured by GlaxoSmithKline Export Ltd (reference product). Both products were well tolerated. PMID:24132707

  7. Scanning gate study of organic thin-film field-effect transistor

    NASA Astrophysics Data System (ADS)

    Aoki, N.; Sudou, K.; Matsusaki, K.; Okamoto, K.; Ochiai, Y.

    2008-03-01

    Scanning gate microscopy (SGM) has been applied for a study of organic thin-film field effect transistor (OFET). In contrast to one-dimensional nano-material such a carbon nanonube or nano-structure such a quantum point contact, visualization a transport characteristic of OFET channel is basically rather difficult since the channel width is much larger than the size of the SGM tip. Nevertheless, Schottky barriers are successfully visualized at the boundary between the metal electrodes and the OFET channel at ambient atmosphere.

  8. Study of methane adsorption on nickel films by Raman effect method

    SciTech Connect

    Plato, S.E.; Bobrov, A.V.; Kadushin, A.A.; Kimmel'feld, Y.M.

    1986-10-01

    The adsorption of methane on nickel films, deposited by the resistivity method in vacuo on a quartz support cooled to 77/sup 0/K, was studied by SERS method (Raman-effect, surface-reinforced). The analysis of the spectrum showed that the adsorption of methane is dissociative in character and CH/sub 2/ and CH/sub 3/ groups are present on the surface, and that the formation of groups containing C-C and C=C bonds is also possible.

  9. A broadband microwave study of the superconducting fluctuations in 2D InOx thin films

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Kim, Minsoo; Wu, Tailung; Ganapathy, Sambandamurthy; Armitage, Peter

    2009-03-01

    We apply a broadband microwave `Corbino' spectrometer covering the range from 10MHz to 20GHz to the study of 2D disordered superconducting InOx thin films. Explicit frequency dependency of the superfluid stiffness and conductivity are obtained down to 270mK. The AC measurements are sensitive to different time scales of the superconducting fluctuations. A number of fluctuation regimes are investigated (gaussian fluctuations, vortex proliferation) as we cool the sample into the low-temperature Kosterlitz-Thouless-Berezinskii- like phase. We discuss our results in terms of prevailing scenarios for fluctuation superconductivity and make connection to other experimental results.

  10. Ultrafast electron diffraction optimized for studying structural dynamics in thin films and monolayers.

    PubMed

    Badali, D S; Gengler, R Y N; Miller, R J D

    2016-05-01

    A compact electron source specifically designed for time-resolved diffraction studies of free-standing thin films and monolayers is presented here. The sensitivity to thin samples is achieved by extending the established technique of ultrafast electron diffraction to the "medium" energy regime (1-10 kV). An extremely compact design, in combination with low bunch charges, allows for high quality diffraction in a lensless geometry. The measured and simulated characteristics of the experimental system reveal sub-picosecond temporal resolution, while demonstrating the ability to produce high quality diffraction patterns from atomically thin samples. PMID:27226978

  11. Film formation of ω-aminoalkylcellulose carbamates--a quartz crystal microbalance (QCM) study.

    PubMed

    Elschner, Thomas; Doliška, Aleš; Bračič, Matej; Stana-Kleinschek, Karin; Heinze, Thomas

    2015-02-13

    The film formation of novel ω-aminoalkylcellulose carbamates on gold surface was studied by means of quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). The influence of the pH value of the buffer solution, the concentration, the degree of polymerization, and the structure (spacer length) of the polymers on the coating was investigated. The layer formation was explained based on the pKa value and the degree of substitution of the ω-aminoalkylcellulose carbamates determined by potentiometric titration. This work provides novel supporting materials that might be applied in field of immobilization of biomolecules. PMID:25458279

  12. Structural studies of tetrathiafulvalene-tetracyanoquinodimethane thin films by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Ara, Norihiko; Kawazu, Akira; Shigekawa, Hidemi; Yase, Kiyoshi; Yoshimura, Masamichi

    1995-06-01

    Thin films of tetrathiafulvanene-tetracyanoquinodimethane (TTF-TCNQ) grown on mica substrates by vacuum deposition were studied by scanning tunneling microscopy (STM). STM images displayed the usual arrangement of alternative TTF and TCNQ columns aligned parallel to the crystal b axis. However, in addition to the same phase as that of a TTF-TCNQ bulk crystal, a new phase is observed. In this new phase the tilt angles the TCNQ and TTF molecular planes make with the a×b axis are different from those observed in the normal phase. This new phase can be explained by the introduction of a stacking fault on the surface.

  13. Apparatus for the study of silicon film deposition and silicon etching

    NASA Astrophysics Data System (ADS)

    Benziger, Jay

    1987-07-01

    A special vacuum system used to study the surface reactions in thin film deposition and etching was equipped with surface analytical techniques and ion sputtering for preparing and characterizing surfaces. X-ray and ultraviolet photoelectron spectroscopy systems were obtained from Vacuum Science Workshop and installed in a 2-chamber vacuum system along with an ion sputtering gun for sample cleaning. These techniques will be used in conjunction with infrared ellipsometry and modulated molecular beam techniques to elucidate the kinetics and mechanisms of surface reactions of silicon deposition and etching.

  14. Ultrafast electron diffraction optimized for studying structural dynamics in thin films and monolayers

    PubMed Central

    Badali, D. S.; Gengler, R. Y. N.; Miller, R. J. D.

    2016-01-01

    A compact electron source specifically designed for time-resolved diffraction studies of free-standing thin films and monolayers is presented here. The sensitivity to thin samples is achieved by extending the established technique of ultrafast electron diffraction to the “medium” energy regime (1–10 kV). An extremely compact design, in combination with low bunch charges, allows for high quality diffraction in a lensless geometry. The measured and simulated characteristics of the experimental system reveal sub-picosecond temporal resolution, while demonstrating the ability to produce high quality diffraction patterns from atomically thin samples. PMID:27226978

  15. Temperature-controlled neutron reflectometry sample cell suitable for study of photoactive thin films

    SciTech Connect

    Yager, Kevin G.; Tanchak, Oleh M.; Barrett, Christopher J.; Watson, Mike J.; Fritzsche, Helmut

    2006-04-15

    We describe a novel cell design intended for the study of photoactive materials using neutron reflectometry. The cell can maintain sample temperature and control of ambient atmospheric environment. Critically, the cell is built with an optical port, enabling light irradiation or light probing of the sample, simultaneous with neutron reflectivity measurements. The ability to measure neutron reflectivity with simultaneous temperature ramping and/or light illumination presents unique opportunities for measuring photoactive materials. To validate the cell design, we present preliminary results measuring the photoexpansion of thin films of azobenzene polymer.

  16. ARPES studies on FeTe1-x Se x iron chalcogenides epitaxial thin films

    NASA Astrophysics Data System (ADS)

    Innocenti, Davide; Moreschini, Luca; Chang, Young Jun; Walter, Andrew; Bostwick, Aaron; di Castro, Daniele; Tebano, Antonello; Medaglia, Pier Gianni; Bellingeri, Emilio; Pallecchi, Ilaria; Ferdeghini, Carlo; Balestrino, Giuseppe; Rotenberg, Eli

    2011-03-01

    The physics of iron-based chalcogenides raises fundamental questions on the interplay of magnetic order and electron pairing at the origin of the superconducting state. We have performed angle-resolved photemission spectroscopy (ARPES) studies on high-quality epitaxial thin films of FeTe 1-x Se x , grown by in situ pulsed laser deposition (PLD) on beamline 7.0.1 at the ALS. Specifically, we are able to show the evolution of the band structure as a function of x. We discuss our experimental results in comparison to the available theoretical band calculations.

  17. A study of nucleation and growth of thin films by means of computer simulation: General features

    NASA Technical Reports Server (NTRS)

    Salik, J.

    1984-01-01

    Some of the processes involved in the nucleation and growth of thin films were simulated by means of a digital computer. The simulation results were used to study the nucleation and growth kinetics resulting from the various processes. Kinetic results obtained for impingement, surface migration, impingement combined with surface migration, and with reevaporation are presented. A substantial fraction of the clusters may form directly upon impingement. Surface migration results in a decrease in cluster density, and reevaporation of atoms from the surface causes a further reduction in cluster density.

  18. Structure and Morphology Study of Cobalt Oxide Doped Silica Nanocomposite Films

    NASA Astrophysics Data System (ADS)

    Drasovean, Romana; Monteiro, Regina; Cherif, Mourad

    2010-01-01

    Cobalt oxide doped silica films were synthesized by a dip-coating technique. Initial compounds were cobalt acetate Co(CH3COO)2ṡ4H2O and tetraethoxysilane Si(OC2H5)4. The chemical composition was studied by X-ray diffraction and UV-Vis spectroscopy. The morphology analyses were carried out by means of atomic force microscopy. The average diameter of cobalt oxide dispersed particles increases with the molar ratio Co:Si and with the aging time of the initial colloidal solution.

  19. Study on properties of Al film on CFRP after cryogenic-thermal cycling

    NASA Astrophysics Data System (ADS)

    Sheng-hu, Wu; Zhan-ji, Ma; Geng-jie, Xiao; Dong-cai, Zhao; Ni, Ren

    Al film on CFRP has been tested by cryogenic-thermal cycling according to the especial condition of space. Properties of aluminum film have been characterized by electron pull apparatus, XRD and SEM. The result shows that the adhesion of Al film increases slowly at early stage of cryogenic-thermal cycling. When the times of cryogenic-thermal cycling exceed 50, the adhesion of Al film becomes stability, and then the adhesion of Al film decrease slowly when cycling times from 100 to 600. After 600 times, the adhesion of Al film becomes stability again. The microcrack appears on the surface of Al film after 50 times, and the amounts of microcrack increase and microcrack is coarsening versus times of cryogenic-thermal cycling. The structure of Al film is changing slowly during cryogenic-thermal cycling.

  20. An Experimental Study of the Effect of Wake Passing on Turbine Blade Film Cooling

    NASA Technical Reports Server (NTRS)

    Heidmann, James D.; Lucci, Barbara L.; Reshotko, Eli

    1997-01-01

    The effect of wake passing on the showerhead film cooling performance of a turbine blade has been investigated experimentally. The experiments were performed in an annular turbine cascade with an upstream rotating row of cylindrical rods. Nickel thin-film gauges were used to determine local film effectiveness and Nusselt number values for various injectants, blowing ratios, and Strouhal numbers. Results indicated a reduction in film effectiveness with increasing Strouhal number, as well as the expected increase in film effectiveness with blowing ratio. An equation was developed to correlate the span-average film effectiveness data. The primary effect of wake unsteadiness was found to be correlated by a streamwise-constant decrement of 0.094.St. Steady computations were found to be in excellent agreement with experimental Nusselt numbers, but to overpredict experimental film effectiveness values. This is likely due to the inability to match actual hole exit velocity profiles and the absence of a credible turbulence model for film cooling.

  1. Low energy positron flux generator for lifetime studies in thin films

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; St. Clair, Terry L.; Eftekhari, Abe

    1991-01-01

    A slow positron flux generator for positron annihilation spectroscopic measurements in thin polymer films is described. The advantages of this generator include operability at room temperature and atmospheric pressure without special test film preparaton requirements.

  2. Study of Optical and Electrical Properties of In2S3:Sn Films Deposited by Spray Pyrolysis

    NASA Astrophysics Data System (ADS)

    Kraini, M.; Bouguila, N.; Halidou, I.; Moadhen, A.; Vázquez-Vázquez, C.; López-Quintela, M. A.; Alaya, S.

    2015-07-01

    Tin-doped In2S3 films were grown by the chemical spray pyrolysis method using compressed air as a carrier gas. Tin is incorporated in the solution using SnCl4. Structural and optical properties of films were investigated by x-ray diffraction (XRD), absorption, Raman and photoluminescence spectroscopies. Field emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy were used to explore the surface morphology. The properties of In2S3 thin films are influenced by Sn doping. XRD studies revealed that the deposited films were polycrystalline in nature exhibiting cubic structure and oriented preferentially towards (111). According to FESEM, the surface morphology of the films was free of defects. Raman studies showed different peaks related to In2S3 phase and did not show any secondary phases of In-Sn and Sn-S. In2S3:Sn films exhibited transparency over 60-85% in the visible and infrared regions. The optical band gap was found to vary in the range 2.71-2.58 eV for direct transitions. The room temperature photoluminescence (PL) studies revealed two PL bands, centered at 529 nm (band A) and 725 nm (band B). From these results, one can conclude that our material can be used as transmittive windows in low-cost solar cells. The conductance and capacitance characterization at ambient temperature were also investigated and gave interesting physical properties for photovoltaic applications.

  3. Studies of ferroelectric heterostructure thin films, interfaces, and device-related processes via in situ analytical techniques.

    SciTech Connect

    Aggarwal, S.; Auciello, O.; Dhote, A. M.; Gao, Y.; Gruen, D. M.; Im, J.; Irene, E. A.; Krauss, A. R.; Muller, A. H.; Ramesh, R.

    1999-06-29

    The science and technology of ferroelectric thin films has experienced an explosive development during the last ten years. Low-density non-volatile ferroelectric random access memories (NVFRAMS) are now incorporated in commercial products such as ''smart cards'', while high permittivity capacitors are incorporated in cellular phones. However, substantial work is still needed to develop materials integration strategies for high-density memories. We have demonstrated that the implementation of complementary in situ characterization techniques is critical to understand film growth and device processes relevant to device development. We are using uniquely integrated time of flight ion scattering and recoil spectroscopy (TOF-ISARS) and spectroscopic ellipsometry (SE) techniques to perform in situ, real-time studies of film growth processes in the high background gas pressure required to growth ferroelectric thin films. TOF-ISARS provides information on surface processes, while SE permits the investigation of buried interfaces as they are being formed. Recent studies on SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub x}Sr{sub 1{minus}x}TiO{sub 3} (BST) film growth and interface processes are discussed. Direct imaging of ferroelectric domains under applied electric fields can provide valuable information to understand domain dynamics in ferroelectric films. We discuss results of piezoresponse scanning force microscopy (SFM) imaging for nanoscale studies of polarization reversal and retention loss in Pb(Zr{sub x}Ti{sub 1{minus}x})O{sub 3} (PZT)-based capacitors. Another powerful technique suitable for in situ, real-time characterization of film growth processes and ferroelectric film-based device operation is based on synchrotrons X-ray scattering, which is currently being implemented at Argonne National Laboratory.

  4. Study of anisotropy of spin cast and vapor deposited polyimide films using internal reflection techniques

    SciTech Connect

    Liberman, V.

    1996-11-01

    We have compared anisotropy of spin cast and vapor deposited polyimide (VDP) films, using internal reflection infrared spectroscopy. The films were deposited directly on the internal reflection element. We find that spin cast films are more anisotropic than their VDP counterparts, with the polyimide chains tending to align parallel to the substrate. Both films are found to contain more and less ordered regions. Within the ordered regions, the plane of the phenyl ring tends to align parallel to the substrate.

  5. Electrochemical signature of mismatch in overhang DNA films: a scanning electrochemical microscopic study.

    PubMed

    Shamsi, Mohtashim Hassan; Kraatz, Heinz-Bernhard

    2013-06-21

    High throughput DNA basepair mismatch detection is an ultimate goal for earlier and point-of-care diagnostics. However, the size of a target sequence on single nucleotide mismatch detection will critically impact the design of sensors in future. To study the potential impact of target size, the probe and target strands of unequal size were hybridized in the absence and presence of single nucleotide mismatches along the sequence. After hybridization, the shorter target sequences form overhangs in the probe strand while longer target sequences form overhangs in the complementary strand. The resulting double stranded DNA hybrids were printed on gold surfaces and the electrochemical response of the films was studied by scanning electrochemical microscopy without signal amplification and label. The redox mediator, [Fe(CN)(6)](4-), experiences lower repulsion in the vicinity of mismatch containing ds-DNA films, which ultimately manifests into higher feedback current regardless of the size and hybridization position of the complementary strands. Kinetic rate constants monitored right above the ds-DNA films show k(0) = 4.5 ± 0.1 × 10(-5) cm s(-1) for the short sequence hybridized at the upper portion of the probe while k(0) = 4.1 ± 0.2 × 10(-5) cm s(-1) for longer complementary strands which has only top overhang. It suggests that hybridization position is important for mismatch detection in short complementary stands. However, in longer complementary strands, mismatches are easily detectable in the absence of bottom overhangs. PMID:23671908

  6. Latin America: A Filmic Approach. Latin American Studies Program, Film Series No. 1.

    ERIC Educational Resources Information Center

    Campbell, Leon G.; And Others

    This document describes a university course designed to provide an historical understanding of Latin America through feature films. The booklet contains an introductory essay on the teaching of a film course on Latin America, a general discussion of strengths and weaknesses of student analyses of films, and nine analyses written by students during…

  7. The Art of the Popular Film Adds Depth to Multicultural Studies.

    ERIC Educational Resources Information Center

    Rosenberg, Howard

    1979-01-01

    A narrative description is given of a 14-week interdisciplinary (art and education) course offered by the University of Nevada, Reno. The course utilized commercial films and dealt with the Black, Asian, Chicano, and Native American experience. Films used, student comments, and the students' film evaluation form are included. (SJL)

  8. Comparative study on structural and optical properties of CdS films fabricated by three different low-cost techniques

    NASA Astrophysics Data System (ADS)

    Ravichandran, K.; Philominathan, P.

    2009-03-01

    Highly crystalline and transparent cadmium sulphide films were fabricated at relatively low temperature by employing an inexpensive, simplified spray technique using perfume atomizer (generally used for cosmetics). The structural, surface morphological and optical properties of the films were studied and compared with that prepared by conventional spray pyrolysis using air as carrier gas and chemical bath deposition. The films deposited by the simplified spray have preferred orientation along (1 0 1) plane. The lattice parameters were calculated as a = 4.138 Å and c = 6.718 Å which are well agreed with that obtained from the other two techniques and also with the standard data. The optical transmittance in the visible range and the optical band gap were found as 85% and 2.43 eV, respectively. The structural and optical properties of the films fabricated by the simplified spray are found to be desirable for opto-electronic applications.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  10. Fabrication and humidity sensing performance studies of a fluorescent film based on a cholesteryl derivative of perylene bisimide.

    PubMed

    Zhang, Shujuan; Zhou, Feng; Peng, Haonan; Liu, Taihong; Ding, Liping; Fang, Yu

    2016-08-01

    A fluorescent film based on a cholesteryl derivative of perylene bisimide (PTCDI-co-CholDEA) was fabricated via utilization of an electrostatic spinning technique on a glass plate surface. SEM studies revealed that the film was characterized by fibrous network structure. It is the structure and the chemical composition that make the fluorescence emission of the film sensitive to the variation of local environmental humidity. The sensitivity of the sensing is 0.1497 (×10(4)a.u. of the intensity)/1% RH, of which RH is the abbreviation of relative humidity. The maximum quenching efficiency of the film is 55.4% when humidity reaches 97% RH. Furthermore, the sensing process is fully reversible, and presence of other commonly found liquids shows little effect to the monitoring process. PMID:27131145

  11. An atomic force microcopy study of the mechanical and electricalproperties of monolayer films of molecules with aromatic end groups

    SciTech Connect

    Fang, Liang; Park, J.Y.; Ma, H.; Jen, A.K.-Y.; Salmeron, M.

    2007-09-06

    The effect of intermolecular {pi}-{pi} stacking on the electrical and mechanical properties of monolayer films molecules containing aromatic groups was studied using atomic force microscopy. Two types of aromatic molecules, (4-mercaptophenyl) anthrylacetylene (MPAA) and (4-mercaptophenyl)-phenylacetylene (MPPA) were used as model systems with different {pi}-{pi} stacking strength. Monolayer films of these molecules on Au(111) surfaces exhibited conductivities differing by more than one order of magnitude, MPAA being the most conductive and MPPA the least conductive. The response to compressive loads by the AFM tip was also found to be very different for both molecules. In MPAA films distinct molecular conductivity changes are observed upon mechanical perturbation. This effect however was not observed on the MPPA film, where intermolecular {pi}-{pi} interactions are likely weaker.

  12. Ferromagnetism studies of Cu-doped and (Cu, Al) co-doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Wu, S. Z.; Yang, H. L.; Xu, X. G.; Miao, J.; Jiang, Y.

    2011-01-01

    We have studied the room temperature ferromagnetism (FM) in Cu-doped and (Cu, Al) co-doped ZnO thin films which were grown on quartz substrates by chemical method based on a sol-gel process combining with spin-coating technology. X-ray diffraction (XRD) patterns demonstrate that both the Cu-doped and (Cu, Al) co-doped ZnO films have the hexagonal wurtzite structure with c-axis orientation. Alternating Gradient Magnetometer (AGM) measurements confirm that all the doped ZnO samples are ferromagnetic at room temperature. When the doped Cu content is 1 %, the Cu-doped ZnO film has the strongest FM. The FM significantly decreases in the (Cu, Al) co-doped ZnO films. The doping of Al ions suppresses the FM induced by the doped Cu ions.

  13. Focused ion beam patterned Fe thin films A study by selective area Stokes polarimetry and soft x-Ray microscopy

    SciTech Connect

    Cook, P. J.; Shen, T. H.; Grundy, P. J.; Im, M.-Y.; Fischer, P.; Morton, S. A.; Kilcoyne, A. L. D.

    2010-11-14

    We demonstrate the potential to modify the magnetic behavior and structural properties of ferromagnetic thin films using focused ion beam 'direct-write' lithography. Patterns inspired by the split-ring resonators often used as components in meta-materials were defined upon 15 nm Fe films using a 30 keV Ga{sup +} focused ion beam at a dose of 2 x 10{sup 16} ions cm{sup -2}. Structural, chemical and magnetic changes to the Fe were studied using transmission soft X-ray microscopy at the ALS, Berkeley CA. X-ray absorption spectra showed a 23% reduction in the thickness of the film in the Ga irradiated areas, but no chemical change to the Fe was evident. X-ray images of the magnetic reversal process show domain wall pinning around the implanted areas, resulting in an overall increase in the coercivity of the film. Transmission electron microscopy showed significant grain growth in the implanted regions.

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

    PubMed Central

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

    2013-01-01

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

  15. Comparative Study of Thermal Stability of NiFe and NiFeTa Thin Films Grown by Cosputtering Technique

    NASA Astrophysics Data System (ADS)

    Phuoc, Nguyen N.; Ong, C. K.

    2016-08-01

    A comparative study of the thermal behavior of dynamic permeability spectra for compositionally graded NiFeTa and uniform-composition NiFe thin films has been carried out. We found that the resonance frequency of the compositionally graded NiFeTa film increased with increasing temperature, while it decreased for the case of the uniform-composition NiFe thin film. This finding unambiguously suggests that the compositional gradient of the film is the only reason for the increase of the magnetic anisotropy with temperature due to its stress-induced origin, while the cosputtering technique does not play any role in this peculiar behavior. The temperature dependence of the frequency linewidth is also presented and discussed.

  16. Fabrication and humidity sensing performance studies of a fluorescent film based on a cholesteryl derivative of perylene bisimide

    NASA Astrophysics Data System (ADS)

    Zhang, Shujuan; Zhou, Feng; Peng, Haonan; Liu, Taihong; Ding, Liping; Fang, Yu

    2016-08-01

    A fluorescent film based on a cholesteryl derivative of perylene bisimide (PTCDI-co-CholDEA) was fabricated via utilization of an electrostatic spinning technique on a glass plate surface. SEM studies revealed that the film was characterized by fibrous network structure. It is the structure and the chemical composition that make the fluorescence emission of the film sensitive to the variation of local environmental humidity. The sensitivity of the sensing is 0.1497 (× 104 a.u. of the intensity)/1% RH, of which RH is the abbreviation of relative humidity. The maximum quenching efficiency of the film is 55.4% when humidity reaches 97% RH. Furthermore, the sensing process is fully reversible, and presence of other commonly found liquids shows little effect to the monitoring process.

  17. Positron annihilation studies of vacancy related defects in ceramic and thin film Pb(Zr,Ti)O{sub 3} materials

    SciTech Connect

    Keeble, D.J.; Krishnan, A.; Umlor, M.T.; Lynn, K.G.; Warren, W.L.; Dimos, D.; Tuttle, B.A.; Ramesh, R.; Poindexter, E.H.

    1994-07-01

    Preliminary positron annihilation studies of ceramic and thin film Pb(Zr,Ti)O{sub 3} (PZT) materials have been completed. This paper examines effects of processing conditions on vacancy related defects. Positron lifetime measurements on bulk PLZT plates showed an increase in positron trapping to a defect state with increasing grain size consistent with trapping to lead vacancy related defects formed through lead oxide loss during processing. Variable energy positron beam measurements were completed on bulk PLZT plates, sol-gel PZT thin films and laser ablated PLZT thin films. Films processed in a reduced oxygen atmosphere were found to give a higher S-parameter, due to an increase in concentration of neutral or negatively charged vacancy type defects, compared with material processed in an oxidizing ambient.

  18. Systematic studies on transition layers of carbides between CVD diamond films and substrates of strong carbide-forming elements

    NASA Astrophysics Data System (ADS)

    Jiang, Xiang-Liu; Zhang, Fang-Qing; Li, Jiang-Qi; Yang, Bin; Chen, Guang-Hua

    1991-12-01

    The nucleation and growth mechanism of polycrystalline diamond films prepared by chemical vapor deposition (CVD) have received increasing research interest. To verify the existence of the transition layers between CVD diamond films and substrates, and to investigate their composition, structure and properties are very meaningful research topics for understanding the mechanism of diamond film growth and developing the applications of CVD diamond films. In this work, the transition layers of carbides for the substrates of molybdenum (Mo), silicon (Si), tungsten (W), tantalum (Ta), and niobium (Nb) and titanium (Ti) have been systematically studied by x-ray diffraction characterization. The experiment results have provided evidence of the existence of transition layers and have revealed that the transition layers are polycrystalline Mo2C, SiC, WC and W2C, TaC and Ta2C, NbC and Nb2C, as well as TiC for the substrates of Mo, Si, W, Ta, Nb and Ti, respectively.

  19. Quantitative study of temperature-dependent order in thin films of cylindrical morphology block copolymer

    NASA Astrophysics Data System (ADS)

    Mishra, Vindhya; Kramer, Edward

    2010-03-01

    Disordering and defect generation in block copolymer systems at high temperatures is of significance to get a better understanding of the physics governing these systems, which can also direct efforts to minimize them. We have studied the smectic-nematic-isotropic transition in confined monolayers and bilayers of cylindrical morphology poly (styrene-b-2vinyl pyridine) diblock copolymer. Previous studies of melting phenomena in block copolymer thin films have relied on quantitative AFM studies alone. We have supplemented AFM studies with grazing incidence small angle X-ray diffraction lineshape analysis to quantify the decay of translational and orientational order with increasing temperature. The results have been interpreted in the context of the Toner-Nelson theory of melting for layered systems.

  20. A physicochemical study of sugar palm (Arenga Pinnata) starch films plasticized by glycerol and sorbitol

    NASA Astrophysics Data System (ADS)

    Poeloengasih, Crescentiana D.; Pranoto, Yudi; Hayati, Septi Nur; Hernawan, Rosyida, Vita T.; Prasetyo, Dwi J.; Jatmiko, Tri H.; Apriyana, Wuri; Suwanto, Andri

    2016-02-01

    The present work explores the physicochemical characteristics of sugar palm starch film for a potential hard capsule purpose. Sugar palm (Arenga pinnata) starch films were plasticized with glycerol or sorbitol in various concentrations (30% up to 50% w/w starch). Their effects on physicochemical properties of the films were investigated. The results showed that sugar palm starch was successfully developed as the main material of film using casting method. Incorporation of both glycerol or sorbitol affected the properties of films in different ways. It was found that thickness and solubility increased as plasticizer concentration increased, whereas retraction ratio, swelling degree and swelling thickness decreased with the increased plasticizer concentration.