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Sample records for adsorbed film thickness

  1. Adsorbed films of three-patch colloids: continuous and discontinuous transitions between thick and thin films.

    PubMed

    Dias, C S; Araújo, N A M; Telo da Gama, M M

    2014-09-01

    We investigate numerically the role of spatial arrangement of the patches on the irreversible adsorption of patchy colloids on a substrate. We consider spherical three-patch colloids and study the dependence of the kinetics on the opening angle between patches. We show that growth is suppressed below and above minimum and maximum opening angles, revealing two absorbing phase transitions between thick and thin film regimes. While the transition at the minimum angle is continuous, in the directed percolation class, that at the maximum angle is clearly discontinuous. For intermediate values of the opening angle, a rough colloidal network in the Kardar-Parisi-Zhang universality class grows indefinitely. The nature of the transitions was analyzed in detail by considering bond flexibility, defined as the dispersion of the angle between the bond and the center of the patch. For the range of flexibilities considered we always observe two phase transitions. However, the range of opening angles where growth is sustained increases with flexibility. At a tricritical flexibility, the discontinuous transition becomes continuous. The practical implications of our findings and the relation to other nonequilibrium transitions are discussed. PMID:25314441

  2. Thick-Film Carbon Dioxide Sensor via Anodic Adsorbate Stripping Technique and Its Structural Dependence

    PubMed Central

    Photinon, Kanokorn; Wang, Shih-Han; Liu, Chung-Chiun

    2009-01-01

    A three-electrode based CO2 sensor was fabricated using thick-film technology. The performance of this sensor was further enhanced by incorporating platinum nanoparticles onto the working electrode surface. An eight-fold increase in the signal output was obtained from the electrode with the platinum nanoparticles. The sensing output was linearly related to the CO2 presented. Stability measurements demonstrated that the decline of the active surface area and the sensitivity of the sensor were 8% and 13%, respectively, over a two week period of time. The sensor response appeared to be a structural dependence of the crystallographic orientation of platinum electrode. PMID:22399993

  3. Thick film hydrogen sensor

    DOEpatents

    Hoffheins, Barbara S.; Lauf, Robert J.

    1995-01-01

    A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.

  4. Thick film hydrogen sensor

    DOEpatents

    Hoffheins, B.S.; Lauf, R.J.

    1995-09-19

    A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors. 8 figs.

  5. Thick Film Interference.

    ERIC Educational Resources Information Center

    Trefil, James

    1983-01-01

    Discusses why interference effects cannot be seen with a thick film, starting with a review of the origin of interference patterns in thin films. Considers properties of materials in films, properties of the light source, and the nature of light. (JN)

  6. Hydraulic properties of adsorbed water films in unsaturated porous media

    SciTech Connect

    Tokunaga, Tetsu K.

    2009-03-01

    Adsorbed water films strongly influence residual water saturations and hydraulic conductivities in porous media at low saturations. Hydraulic properties of adsorbed water films in unsaturated porous media were investigated through combining Langmuir's film model with scaling analysis, without use of any adjustable parameters. Diffuse double layer influences are predicted to be important through the strong dependence of adsorbed water film thickness (f) on matric potential ({Psi}) and ion charge (z). Film thickness, film velocity, and unsaturated hydraulic conductivity are predicted to vary with z{sup -1}, z{sup -2}, and z{sup -3}, respectively. In monodisperse granular media, the characteristic grain size ({lambda}) controls film hydraulics through {lambda}{sup -1} scaling of (1) the perimeter length per unit cross sectional area over which films occur, (2) the critical matric potential ({Psi}{sub c}) below which films control flow, and (3) the magnitude of the unsaturated hydraulic conductivity when {Psi} < {Psi}{sub c}. While it is recognized that finer textured sediments have higher unsaturated hydraulic conductivities than coarser sands at intermediate {Psi}, the {lambda}{sup -1} scaling of hydraulic conductivity predicted here extends this understanding to very low saturations where all pores are drained. Extremely low unsaturated hydraulic conductivities are predicted under adsorbed film-controlled conditions (generally < 0.1 mm y{sup -1}). On flat surfaces, the film hydraulic diffusivity is shown to be constant (invariant with respect to {Psi}).

  7. Thick film ink chemistry

    NASA Astrophysics Data System (ADS)

    Gehman, R. W.

    1982-03-01

    Twenty-six thick film inks from two vendors were proved for hybrid microcircuit production use. A data base of chemical information was established for all the inks to aid in future diagnostic and failure analysis activities. Efforts included both organic chemical analysis of printing vehicles and binders and inorganic chemical analysis of glass frits and electrically active phases. Analytical methods included infrared spectroscopy, mass spectroscopy, gas chromatography, X-ray fluorescence, emission spectroscopy, atomic absorption spectroscopy, and wet chemical techniques.

  8. System for measuring film thickness

    DOEpatents

    Batishko, Charles R.; Kirihara, Leslie J.; Peters, Timothy J.; Rasmussen, Donald E.

    1990-01-01

    A system for determining the thicknesses of thin films of materials exhibiting fluorescence in response to exposure to excitation energy from a suitable source of such energy. A section of film is illuminated with a fixed level of excitation energy from a source such as an argon ion laser emitting blue-green light. The amount of fluorescent light produced by the film over a limited area within the section so illuminated is then measured using a detector such as a photomultiplier tube. Since the amount of fluorescent light produced is a function of the thicknesses of thin films, the thickness of a specific film can be determined by comparing the intensity of fluorescent light produced by this film with the intensity of light produced by similar films of known thicknesses in response to the same amount of excitation energy. The preferred embodiment of the invention uses fiber optic probes in measuring the thicknesses of oil films on the operational components of machinery which are ordinarily obscured from view.

  9. Computer simulations of adsorbed liquid crystal films

    NASA Astrophysics Data System (ADS)

    Wall, Greg D.; Cleaver, Douglas J.

    2003-01-01

    The structures adopted by adsorbed thin films of Gay-Berne particles in the presence of a coexisting vapour phase are investigated by molecular dynamics simulation. The films are adsorbed at a flat substrate which favours planar anchoring, whereas the nematic-vapour interface favours normal alignment. On cooling, a system with a high molecule-substrate interaction strength exhibits substrate-induced planar orientational ordering and considerable stratification is observed in the density profiles. In contrast, a system with weak molecule-substrate coupling adopts a director orientation orthogonal to the substrate plane, owing to the increased influence of the nematic-vapour interface. There are significant differences between the structures adopted at the two interfaces, in contrast with the predictions of density functional treatments of such systems.

  10. Measuring Thicknesses of Wastewater Films

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Davenport, R. J.

    1987-01-01

    Sensor determines when thickness of film of electrically conductive wastewater on rotating evaporator drum exceeds preset value. Sensor simple electrical probe that makes contact with liquid surface. Made of materials resistant to chemicals in liquid. Mounted on shaft in rotating cylinder, liquid-thickness sensor extends toward cylinder wall so tip almost touches. Sensor body accommodates probe measuring temperature of evaporated water in cylinder.

  11. Applications of film thickness equations

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1983-01-01

    A number of applications of elastohydrodynamic film thickness expressions were considered. The motion of a steel ball over steel surfaces presenting varying degrees of conformity was examined. The equation for minimum film thickness in elliptical conjunctions under elastohydrodynamic conditions was applied to roller and ball bearings. An involute gear was also introduced, it was again found that the elliptical conjunction expression yielded a conservative estimate of the minimum film thickness. Continuously variable-speed drives like the Perbury gear, which present truly elliptical elastohydrodynamic conjunctions, are favored increasingly in mobile and static machinery. A representative elastohydrodynamic condition for this class of machinery is considered for power transmission equipment. The possibility of elastohydrodynamic films of water or oil forming between locomotive wheels and rails is examined. The important subject of traction on the railways is attracting considerable attention in various countries at the present time. The final example of a synovial joint introduced the equation developed for isoviscous-elastic regimes of lubrication.

  12. LTCC Thick Film Process Characterization

    DOE PAGESBeta

    Girardi, M. A.; Peterson, K. A.; Vianco, P. T.

    2016-05-01

    Low temperature cofired ceramic (LTCC) technology has proven itself in military/space electronics, wireless communication, microsystems, medical and automotive electronics, and sensors. The use of LTCC for high frequency applications is appealing due to its low losses, design flexibility and packaging and integration capability. Moreover, we summarize the LTCC thick film process including some unconventional process steps such as feature machining in the unfired state and thin film definition of outer layer conductors. The LTCC thick film process was characterized to optimize process yields by focusing on these factors: 1) Print location, 2) Print thickness, 3) Drying of tapes and panels,more » 4) Shrinkage upon firing, and 5) Via topography. Statistical methods were used to analyze critical process and product characteristics in the determination towards that optimization goal.« less

  13. Hydrodynamic thickness of petroleum oil adsorbed layers in the pores of reservoir rocks.

    PubMed

    Alkafeef, Saad F; Algharaib, Meshal K; Alajmi, Abdullah F

    2006-06-01

    The hydrodynamic thickness delta of adsorbed petroleum (crude) oil layers into the pores of sandstone rocks, through which the liquid flows, has been studied by Poiseuille's flow law and the evolution of (electrical) streaming current. The adsorption of petroleum oil is accompanied by a numerical reduction in the (negative) surface potential of the pore walls, eventually stabilizing at a small positive potential, attributed to the oil macromolecules themselves. After increasing to around 30% of the pore radius, the adsorbed layer thickness delta stopped growing either with time or with concentrations of asphaltene in the flowing liquid. The adsorption thickness is confirmed with the blockage value of the rock pores' area determined by the combination of streaming current and streaming potential measurements. This behavior is attributed to the effect on the disjoining pressure across the adsorbed layer, as described by Derjaguin and Churaev, of which the polymolecular adsorption films lose their stability long before their thickness has approached the radius of the rock pore. PMID:16414057

  14. Adsorbed water and thin liquid films on Mars

    NASA Astrophysics Data System (ADS)

    Boxe, C. S.; Hand, K. P.; Nealson, K. H.; Yung, Y. L.; Yen, A. S.; Saiz-Lopez, A.

    2012-07-01

    At present, bulk liquid water on the surface and near-subsurface of Mars does not exist due to the scarcity of condensed- and gas-phase water, pressure and temperature constraints. Given that the nuclei of soil and ice, that is, the soil solid and ice lattice, respectively, are coated with adsorbed and/or thin liquid films of water well below 273 K and the availability of water limits biological activity, we quantify lower and upper limits for the thickness of such adsorbed/water films on the surface of the Martian regolith and for subsurface ice. These limits were calculated based on experimental and theoretical data for pure water ice and water ice containing impurities, where water ice containing impurities exhibit thin liquid film enhancements, ranging from 3 to 90. Close to the cold limit of water stability (i.e. 273 K), thin liquid film thicknesses at the surface of the Martian regolith is 0.06 nm (pure water ice) and ranges from 0.2 to 5 nm (water ice with impurities). An adsorbed water layer of 0.06 nm implies a dessicated surface as the thickness of one monolayer of water is 0.3 nm but represents 0.001-0.02% of the Martian atmospheric water vapour inventory. Taking into account the specific surface area (SSA) of surface-soil (i.e. top 1 mm of regolith and 0.06 nm adsorbed water layer), shows Martian surface-soil may contain interfacial water that represents 6-66% of the upper- and lower-limit atmospheric water vapour inventory and almost four times and 33%, the lower- and upper-limit Martian atmospheric water vapour inventory. Similarly, taking the SSA of Martian soil, the top 1 mm or regolith at 5 nm thin liquid water thickness, yields 1.10×1013 and 6.50×1013 litres of waters, respectively, 55-325 times larger than Mars' atmospheric water vapour inventory. Film thicknesses of 0.2 and 5 nm represent 2.3×104-1.5×106 litres of water, which is 6.0×10-7-4.0×10-4%, respectively, of a 10 pr μm water vapour column, and 3.0×10-6-4.0×10-4% and 6.0×10

  15. Adsorbed Methane Film Properties in Nanoporous Carbon Monoliths

    NASA Astrophysics Data System (ADS)

    Soo, Yuchoong; Chada, Nagaraju; Beckner, Matthew; Romanos, Jimmy; Burress, Jacob; Pfeifer, Peter

    2013-03-01

    Carbon briquetting can increase methane storage capacity by reducing the useless void volume resulting in a better packing density. It is a robust and efficient space-filling form for an adsorbed natural gas vehicle storage tank. To optimize methane storage capacity, we studied three fabrication process parameters: carbon-to-binder ratio, compaction temperature, and pyrolysis temperature. We found that carbon-to-binder ratio and pyrolysis temperature both have large influences on monolith uptakes. We have been able to optimize these parameters for high methane storage. All monolith uptakes (up to 260 bar) were measured by a custom-built, volumetric, reservoir-type instrument. The saturated film density and the film thickness was determined using linear extrapolation on the high pressure excess adsorption isotherms. The saturated film density was also determined using the monolayer Ono-Kondo model. Film densities ranged from ca. 0.32 g/cm3 - 0.37 g/cm3.The Ono-Kondo model also determines the binding energy of methane. Binding energies were also determined from isosteric heats calculated from the Clausius-Clapeyron equation and compared with the Ono-Kondo model method. Binding energies from Ono-Kondo were ca. 7.8 kJ/mol - 10 kJ/mol. Work funded by California Energy Commission Contract #500-08-022.

  16. Structure and properties of water film adsorbed on mica surfaces

    NASA Astrophysics Data System (ADS)

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-01

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet.

  17. Influence of fluoride-detergent combinations on the visco-elasticity of adsorbed salivary protein films.

    PubMed

    Veeregowda, Deepak H; van der Mei, Henny C; Busscher, Henk J; Sharma, Prashant K

    2011-02-01

    The visco-elasticity of salivary-protein films is related to mouthfeel, lubrication, biofilm formation, and protection against erosion and is influenced by the adsorption of toothpaste components. The thickness and the visco-elasticity of hydrated films (determined using a quartz crystal microbalance) of 2-h-old in vitro-adsorbed salivary-protein films were 43.5 nm and 9.4 MHz, respectively, whereas the dehydrated thickness, measured using X-ray photoelectron spectroscopy, was 2.4 nm. Treatment with toothpaste slurries decreased the thickness of the film, depending on the fluoride-detergent combination involved. Secondary exposure to saliva resulted in a regained thickness of the film to a level similar to its original thickness; however, no association was found between the thickness of hydrated and dehydrated films, indicating differences in film structure. Treatment with stannous fluoride/sodium lauryl sulphate (SnF(2)/SLS)-containing toothpaste slurries yielded a strong, immediate two-fold increase in characteristic film frequency (f(c)) with respect to untreated films, indicating cross-linking in adsorbed salivary-protein films by Sn(2+) that was absent when SLS was replaced with sodium hexametaphosphate (NaHMP). Secondary exposure to saliva of films treated with SnF(2) caused a strong, six-fold increase in f(c) compared with primary salivary-protein films, regardless of whether SLS or NaHMP was the detergent. This suggests that ionized stannous is not directly available for cross-linking in combination with highly negatively charged NaHMP, but becomes slowly available after initial treatment to cause cross-linking during secondary exposure to saliva. PMID:21244507

  18. Vacuum casting of thick polymeric films

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.; Moacanin, J.

    1979-01-01

    Bubble formation and layering, which often plague vacuum-evaporated films, are prevented by properly regulating process parameters. Vacuum casting may be applicable to forming thick films of other polymer/solvent solutions.

  19. Effect of geometry on hydrodynamic film thickness

    NASA Technical Reports Server (NTRS)

    Brewe, D. E.; Hamrock, B. J.; Taylor, C. M.

    1978-01-01

    The influence of geometry on the isothermal hydrodynamic film separating two rigid solids was investigated. Pressure-viscosity effects were not considered. The minimum film thickness is derived for fully flooded conjunctions by using the Reynolds conditions. It was found that the minimum film thickness had the same speed, viscosity, and load dependence as Kapitza's classical solution. However, the incorporation of Reynolds boundary conditions resulted in an additional geometry effect. Solutions using the parabolic film approximation are compared with those using the exact expression for the film in the analysis. Contour plots are shown that indicate in detail the pressure developed between the solids.

  20. Physicochemical controls on absorbed water film thickness in unsaturated geological media

    SciTech Connect

    Tokunaga, T.

    2011-06-14

    Adsorbed water films commonly coat mineral surfaces in unsaturated soils and rocks, reducing flow and transport rates. Therefore, it is important to understand how adsorbed film thickness depends on matric potential, surface chemistry, and solution chemistry. Here, the problem of adsorbed water film thickness is examined through combining capillary scaling with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Novel aspects of this analysis include determining capillary influences on film thicknesses, and incorporating solution chemistry-dependent electrostatic potential at air-water interfaces. Capillary analysis of monodisperse packings of spherical grains provided estimated ranges of matric potentials where adsorbed films are stable, and showed that pendular rings within drained porous media retain most of the 'residual' water except under very low matric potentials. Within drained pores, capillary contributions to thinning of adsorbed films on spherical grains are shown to be small, such that DLVO calculations for flat surfaces are suitable approximations. Hamaker constants of common soil minerals were obtained to determine ranges of the dispersion component to matric potential-dependent film thickness. The pressure component associated with electrical double layer forces was estimated using the compression and linear superposition approximations. The pH-dependent electrical double layer pressure component is the dominant contribution to film thicknesses at intermediate values of matric potential, especially in lower ionic strength solutions (< 10 mol m{sup -3}) on surfaces with higher magnitude electrostatic potentials (more negative than - 50 mV). Adsorbed water films are predicted to usually range in thickness from 1 to 20 nm in drained pores and fractures of unsaturated environments.

  1. Elastic mediated force between nanoparticles adsorbed on smectic films under an external field.

    PubMed

    Pereira, Maria S S; Lyra, Marcelo L; de Oliveira, Italo N

    2013-02-01

    Within the harmonic approximation, we analytically determine the elastic-mediated interaction between colloidal nanoparticles adsorbed on the surface of smectic films under the influence of an external field. Both cases of free-standing films and films deposited over a solid substrate are considered. We show that the asymptotic decay (1/R in free-standing and exponential in deposited films) is not altered by the external field. However, the external field plays distinct roles according to the film configuration, the interparticle distance, the film thickness, and the surface tension at the film-gas interface. We provide a detailed discussion under the light of the distinct mechanisms controlling the undulations of the surface layer. PMID:23496530

  2. Electrochromism of DC magnetron-sputtered TiO2: Role of film thickness

    NASA Astrophysics Data System (ADS)

    Sorar, Idris; Pehlivan, Esat; Niklasson, Gunnar A.; Granqvist, Claes G.

    2014-11-01

    Titanium dioxide films were prepared by reactive DC magnetron sputtering and the role of the film thickness d on the electrochromism was analyzed for 100 < d < 400 nm. The best properties were obtained for the thickest films, which yielded a mid-luminous transmittance modulation of 58% and a corresponding coloration efficiency of 26.3 cm2/C. The films were amorphous according to X-ray diffraction measurements and showed traces of adsorbed water as revealed by infrared spectroscopy.

  3. Thick crystalline films on foreign substrates

    DOEpatents

    Smith, Henry I.; Atwater, Harry A.; Geis, Michael W.

    1986-01-01

    To achieve a uniform texture, large crystalline grains or, in some cases, a single crystalline orientation in a thick (>1 .mu.m) film on a foreign substrate, the film is formed so as to be thin (<1 .mu.m) in a certain section. Zone-melting recrystallization is initiated in the thin section and then extended into the thick section. The method may employ planar constriction patterns of orientation filter patterns.

  4. Thick crystalline films on foreign substrates

    DOEpatents

    Smith, H.I.; Atwater, H.A.; Geis, M.W.

    1986-03-18

    To achieve a uniform texture, large crystalline grains or, in some cases, a single crystalline orientation in a thick (>1 [mu]m) film on a foreign substrate, the film is formed so as to be thin (<1 [mu]m) in a certain section. Zone-melting recrystallization is initiated in the thin section and then extended into the thick section. The method may employ planar constriction patterns of orientation filter patterns. 2 figs.

  5. Unusual Morphologies of Poly(vinyl alcohol) Thin Films Adsorbed on Poly(dimethylsiloxane) Substrates.

    PubMed

    Karki, Akchheta; Nguyen, Lien; Sharma, Bhanushee; Yan, Yan; Chen, Wei

    2016-04-01

    Adsorption of poly(vinyl alcohol) (PVOH), 99% and 88% hydrolyzed poly(vinyl acetate), to poly(dimethylsiloxane) (PDMS) substrates was studied. The substrates were prepared by covalently attaching linear PDMS polymers of 2, 9, 17, 49, and 116 kDa onto silicon wafers. As the PDMS molecular weight/thickness increases, the adsorbed PVOH thin films progressively transition from continuous to discontinuous morphologies, including honeycomb and fractal/droplet. The structures are the result of thin film dewetting that occurs upon exposure to air. The PVOH film thickness does not vary significantly on these PDMS substrates, implicating the PDMS thickness as the cause for the morphology differences. The adsorbed PVOH thin films are less stable and have a stronger tendency to dewet on thicker, more liquid-like PDMS layers. When PVOH(99%) and PVOH(88%) thin films are compared, fractal and droplet morphologies are observed on high molecular weight PDMS substrates, respectively. The formation of the unique fractal features in the PVOH(99%) thin films as well as other crystalline and semicrystalline thin films is most likely driven by crystallization during the dehydration process in a diffusion-limited aggregation fashion. The only significant enhancement in hydrophilicity via PVOH adsorption was obtained on PDMS(2k), which is completely covered with a PVOH thin film. To mimic the lower receding contact angle and less liquid-like character of the PDMS(2k) substrate, light plasma treatment of the higher molecular weight PDMS substrates was carried out. On the treated PDMS substrates, the adsorbed PVOH thin films are in the more continuous honeycomb morphology, giving rise to significantly enhanced wettability. Furthermore, hydrophobic recovery of the hydrophilized PDMS substrates was not observed during a 1 week period. Thus, light plasma oxidation and subsequent PVOH adsorption can be utilized as a means to effectively hydrophilize conventional PDMS substrates. This study

  6. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  7. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus_minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus_minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  8. Systematic Evaluation of Jc Decrease in Thick Film Coated Conductors

    SciTech Connect

    Alex Ignatiev; Dr. Amit Goyal

    2006-05-10

    Address both thickness dependence of Jc, in thick film YBCO coated conductors through an application of a suite of new measurement techniques to thick film wire samples produced by commercially viable coated conductor technologies.

  9. Heat capacity of quantum adsorbates: Hydrogen and helium on evaporated gold films

    SciTech Connect

    Birmingham, J.T. |

    1996-06-01

    The author has constructed an apparatus to make specific heat measurements of quantum gases adsorbed on metallic films at temperatures between 0.3 and 4 K. He has used this apparatus to study quench-condensed hydrogen films between 4 and 923 layers thick with J = 1 concentrations between 0.28 and 0.75 deposited on an evaporated gold surface. He has observed that the orientational ordering of the J = 1 molecules depends on the substrate temperature during deposition of the hydrogen film. He has inferred that the density of the films condensed at the lowest temperatures is 25% higher than in bulk H{sub 2} crystals and have observed that the structure of those films is affected by annealing at 3.4 K. The author has measured the J = 1 to J = 0 conversion rate to be comparable to that of the bulk for thick films; however, he found evidence that the gold surface catalyzes conversion in the first two to four layers. He has also used this apparatus to study films of {sup 4}He less than one layer thick adsorbed on an evaporated gold surface. He shows that the phase diagram of the system is similar to that for {sup 4}He/graphite although not as rich in structure, and the phase boundaries occur at different coverages and temperatures. At coverages below about half a layer and at sufficiently high temperatures, the {sup 4}He behaves like a two-dimensional noninteracting Bose gas. At lower temperatures and higher coverages, liquidlike and solidlike behavior is observed. The Appendix shows measurements of the far-infrared absorptivity of the high-{Tc} superconductor La{sub 1.87}Sr{sub 0.13}CuO{sub 4}.

  10. Nano-Hydroxyapatite Thick Film Gas Sensors

    NASA Astrophysics Data System (ADS)

    Khairnar, Rajendra S.; Mene, Ravindra U.; Munde, Shivaji G.; Mahabole, Megha P.

    2011-12-01

    In the present work pure and metal ions (Co and Fe) doped hydroxyapatite (HAp) thick films have been successfully utilized to improve the structural, morphological and gas sensing properties. Nanocrystalline HAp powder is synthesized by wet chemical precipitation route, and ion exchange process is employed for addition of Co and Fe ions in HAp matrix. Moreover, swift heavy ion irradiation (SHI) technique is used to modify the surface of pure and metal ion exchanged HAp with various ion fluence. The structural investigation of pure and metal ion exchanged HAp thick films are carried out using X-ray diffraction and the presence of functional group is observed by means FTIR spectroscopy. Furthermore, surface morphology is visualized by means of SEM and AFM analysis. CO gas sensing study is carried out for, pure and metal ions doped, HAp thick films with detail investigation on operating temperature, response/recovery time and gas uptake capacity. The surface modifications of sensor matrix by SHI enhance the gas response, response/recovery and gas uptake capacity. The significant observation is here to note that, addition of Co and Fe in HAp matrix and surface modification by SHI improves the sensing properties of HAp films drastically resulting in gas sensing at relatively lower temperatures.

  11. Nano-Hydroxyapatite Thick Film Gas Sensors

    SciTech Connect

    Khairnar, Rajendra S.; Mene, Ravindra U.; Munde, Shivaji G.; Mahabole, Megha P.

    2011-12-10

    In the present work pure and metal ions (Co and Fe) doped hydroxyapatite (HAp) thick films have been successfully utilized to improve the structural, morphological and gas sensing properties. Nanocrystalline HAp powder is synthesized by wet chemical precipitation route, and ion exchange process is employed for addition of Co and Fe ions in HAp matrix. Moreover, swift heavy ion irradiation (SHI) technique is used to modify the surface of pure and metal ion exchanged HAp with various ion fluence. The structural investigation of pure and metal ion exchanged HAp thick films are carried out using X-ray diffraction and the presence of functional group is observed by means FTIR spectroscopy. Furthermore, surface morphology is visualized by means of SEM and AFM analysis. CO gas sensing study is carried out for, pure and metal ions doped, HAp thick films with detail investigation on operating temperature, response/recovery time and gas uptake capacity. The surface modifications of sensor matrix by SHI enhance the gas response, response/recovery and gas uptake capacity. The significant observation is here to note that, addition of Co and Fe in HAp matrix and surface modification by SHI improves the sensing properties of HAp films drastically resulting in gas sensing at relatively lower temperatures.

  12. Percolation effect in thick film superconductors

    SciTech Connect

    Sali, R.; Harsanyi, G.

    1994-12-31

    A thick film superconductor paste has been developed to study the properties of granulated superconductor materials, to observe the percolation effect and to confirm the theory of the conducting mechanism in the superconducting thick films. This paste was also applied to make a superconducting planar transformer. Due to high T{sub c} and advantageous current density properties the base of the paste was chosen to be of Bi(Pb)SrCaCuO system. For contacts a conventional Ag/Pt paste was used. The critical temperature of the samples were between 110 K and 115 K depending on the printed layer thickness. The critical current density at the boiling temperature of the liquid He- was between 200-300 A/cm{sup 2}. The R(T) and V(I) functions were measured with different parameters. The results of the measurements have confirmed the theory of conducting mechanism in the material. The percolation structure model has been built and described. As an application, a superconducting planar thick film transformer was planned and produced. Ten windings of the transformer were printed on one side of the alumina substrate and one winding was printed on the other side. The coupling between the two sides was possible through the substrate. The samples did not need special drying and firing parameters. After the preparation, the properties of the transformer were measured. The efficiency and the losses were determined. Finally, some fundamental advantages and problems of the process were discussed.

  13. Epitaxial piezoelectric thick film heterostructures on silicon

    NASA Astrophysics Data System (ADS)

    Kim, Dong Min

    The significantly higher dielectric permittivity, piezoelectric coefficients and electromechanical coupling coefficients of single crystal relaxor ferroelectrics make them very attractive for medical ultrasound transducers and microelectromechanical systems (MEMS) applications. The potential impact of thin-film relaxor ferroelectrics in integrated actuators and sensor on silicon has stimulated research on the growth and characterization of epitaxial piezoelectric thin films. We have fabricated heterostructures by (1) synthesizing optimally-oriented, epitaxial thin films of Pb(Mg1/3Nb2/3)O3-PbTiO 3 (PMN-PT) on miscut (001) Si wafers with epitaxial (001) SrTiO 3 template layers, where the single crystal form is known to have the giant piezoelectric response, and (2) nano-structuring to reduce the constraint imposed by the underlying silicon substrate. Up to now, the longitudinal piezoelectric coefficient (d33) values of PMN and PMN-PT thin films range from 50 to 200 pC/N have been reported, which are far inferior to the properties of bulk single crystals value (d33 ˜ 2000 pC/N). These might be attributed to substrate constraints, pyrochlore phases and other effects. Here, we have realized the giant d33 values by fabricating epitaxial PMN-PT thick films on silicon. When the PMN-PT film was subdivided into ˜1 mum2 capacitors by focused ion beam processing, a 4 mum thick film shows a low-field d33 of 800 pm/V that increases to over 1200 pm/V under bias, which is the highest d33 value ever realized on silicon substrates. These high piezo-reponse PMN-PT epitaxial heterostructures can be used for multilayered MEMS devices which function with low driving voltage, high frequency ultrasound transducer arrays for medical imaging, and capacitors for charge and energy storage. Since these PMN-PT films are epitaxially integrated with the silicon, they can make use of the well-developed fabrication process for patterning and micromachining of this large-area, cost

  14. Properties of conductive thick-film inks

    NASA Technical Reports Server (NTRS)

    Holtze, R. F.

    1972-01-01

    Ten different conductive inks used in the fabrication of thick-film circuits were evaluated for their physical and handling properties. Viscosity, solid contents, and spectrographic analysis of the unfired inks were determined. Inks were screened on ceramic substrates and fired for varying times at specified temperatures. Selected substrates were given additional firings to simulate the heat exposure received if thick-film resistors were to be added to the same substrate. Data are presented covering the (1) printing characteristics, (2) solderability using Sn-63 and also a 4 percent silver solder, (3) leach resistance, (4) solder adhesion, and (5) wire bonding properties. Results obtained using different firing schedules were compared. A comparison was made between the various inks showing general results obtained for each ink. The changes in firing time or the application of a simulated resistor firing had little effect on the properties of most inks.

  15. Metallic oxide switches using thick film technology

    NASA Technical Reports Server (NTRS)

    Patel, D. N.; Williams, L., Jr.

    1974-01-01

    Metallic oxide thick film switches were processed on alumina substrates using thick film technology. Vanadium pentoxide in powder form was mixed with other oxides e.g., barium, strontium copper and glass frit, ground to a fine powder. Pastes and screen printable inks were made using commercial conductive vehicles and appropriate thinners. Some switching devices were processed by conventional screen printing and firing of the inks and commercial cermet conductor terminals on 96% alumina substrates while others were made by applying small beads or dots of the pastes between platinum wires. Static, and dynamic volt-ampere, and pulse tests indicate that the switching and self-oscillatory characteristics of these devices could make them useful in memory element, oscillator, and automatic control applications.

  16. Thick film wireless and powerless strain sensor

    NASA Astrophysics Data System (ADS)

    Jia, Yi; Sun, Ke

    2006-03-01

    The development of an innovative wireless strain sensing technology has a great potential to extend its applications in manufacturing, civil engineering and aerospace industry. This paper presents a novel wireless and powerless strain sensor with a multi-layer thick film structure. The sensor employs a planar inductor (L) and capacitive transducer (C) resonant tank sensing circuit, and a strain sensitive material of a polarized polyvinylidene fluoride (PVDF) piezoelectric thick film to realize the wireless strain sensing by strain to frequency conversion and to receive radio frequency electromagnetic energy for powering the sensor. The prototype sensor was designed and fabricated. The results of calibration on a strain constant cantilever beam show a great linearity and sensitivity about 0.0013 in a strain range of 0-0.018.

  17. Residual Stress Analysis in Thick Uranium Films

    SciTech Connect

    Hodge, A M; Foreman, R J; Gallegos, G F

    2004-12-06

    Residual stress analysis was performed on thick, 1.0 to 25 {micro}m, depleted Uranium (DU) films deposited on an Al substrate by magnetron sputtering. Two distinct characterization techniques were used to measure substrate curvature before and after deposition. Stress evaluation was performed using the Benabdi/Roche equation, which is based on beam theory of a bi-layer material. The residual stress evolution was studied as a function of coating thickness and applied negative bias voltage (0-300V). The stresses developed were always compressive; however, increasing the coating thickness and applying a bias voltage presented a trend towards more tensile stresses and thus an overall reduction of residual stresses.

  18. Flow fields in soap films: Relating viscosity and film thickness

    NASA Astrophysics Data System (ADS)

    Prasad, V.; Weeks, Eric R.

    2009-08-01

    We follow the diffusive motion of colloidal particles in soap films with varying h/d , where h is the thickness of the film and d is the diameter of the particles. The hydrodynamics of these films are determined by looking at the correlated motion of pairs of particles as a function of separation R . The Trapeznikov approximation [A. A. Trapeznikov, Proceedings of the 2nd International Congress on Surface Activity (Butterworths, London, 1957), p. 242] is used to model soap films as an effective two-dimensional (2D) fluid in contact with bulk air phases. The flow fields determined from correlated particle motions show excellent agreement with what is expected for the theory of 2D fluids for all our films where 0.6≤h/d≤14.3 , with the 2D shear viscosity matching that predicted by Trapeznikov. However, the parameters of these flow fields change markedly for thick films (h/d>7±3) . Our results indicate that three-dimensional effects become important for these thicker films, despite the flow fields still having a 2D character.

  19. Thick Films: Electronic Applications. (Latest citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning the design, development, fabrication, and evaluation of thick film electronic devices. Thick film solar cells, thick films for radiation conduction, deposition processes, conductive inks are among the topics discussed. Applications in military and civilian avionics are examined.

  20. Determination of thin film refractive index and thickness by means of film phase thickness

    NASA Astrophysics Data System (ADS)

    Nenkov, Milen R.; Pencheva, Tamara G.

    2008-06-01

    A new approach for determination of refractive index dispersion n( λ) (the real part of the complex refractive index) and thickness d of thin films of negligible absorption and weak dispersion is proposed. The calculation procedure is based on determination of the phase thickness of the film in the spectral region of measured transmittance data. All points of measured spectra are included in the calculations. Barium titanate thin films are investigated in the spectral region 0.38-0.78 μm and their n( λ) and d are calculated. The approach is validated using Swanepoel’s method and it is found to be applicable for relatively thin films when measured transmittance spectra have one minimum and one maximum only.

  1. Determination of thin film refractive index and thickness by means of film phase thickness

    NASA Astrophysics Data System (ADS)

    Nenkov, Milen; Pencheva, Tamara

    2008-06-01

    A new approach for determination of refractive index dispersion n(λ) (the real part of the complex refractive index) and thickness d of thin films of negligible absorption and weak dispersion is proposed. The calculation procedure is based on determination of the phase thickness of the film in the spectral region of measured transmittance data. All points of measured spectra are included in the calculations. Barium titanate thin films are investigated in the spectral region 0.38-0.78 μm and their n(λ) and d are calculated. The approach is validated using Swanepoel's method and it is found to be applicable for relatively thin films when measured transmittance spectra have one minimum and one maximum only.

  2. Method for preparing a thick film conductor

    DOEpatents

    Nagesh, Voddarahalli K.; Fulrath, deceased, Richard M.

    1978-01-01

    A method for preparing a thick film conductor which comprises providing surface active glass particles, mixing the surface active glass particles with a thermally decomposable organometallic compound, for example, a silver resinate, and then decomposing the organometallic compound by heating, thereby chemically depositing metal on the glass particles. The glass particle mixture is applied to a suitable substrate either before or after the organometallic compound is thermally decomposed. The resulting system is then fired in an oxidizing atmosphere, providing a microstructure of glass particles substantially uniformly coated with metal.

  3. The influence of binder film thickness on the mechanical properties of binder films in tension.

    PubMed

    Ononokpono, O E; Spring, M S

    1988-02-01

    The physicomechanical properties of films of different thicknesses, made from methylcellulose and gelatinized maize starch, have been studied in tension. There was a linear relation between film thickness and tensile strength, toughness, elastic resilence and elongation at fracture. Young's modulus increased with decreasing film thickness particularly with films with a thickness of less than 15 micron. PMID:2897444

  4. Quartz Microbalance Study of 400-angstrom Thick Films near the lambda Point

    NASA Technical Reports Server (NTRS)

    Chan, Moses H. W.

    2003-01-01

    In a recent measurement we observed the thinning of an adsorbed helium film induced by the confinement of critical fluctuations a few millikelvin below the lambda point. A capacitor set-up was used to measure this Casimir effect. In this poster we will present our measurement of an adsorbed helium film of 400 angstroms near the lambda point with a quartz microbalance. For films this thick, we must take into account the non-linear dynamics of the shear waves in the fluid. In spite of the added complications, we were able to confirm the thinning of the film due to the Casimir effect and the onset of the superfluid transition. In addition, we observe a sharp anomaly at the bulk lambda point, most likely related to critical dissipation of the first sound. This work is carried out in collaboration with Rafael Garcia, Stephen Jordon and John Lazzaretti. This work is funded by NASA's Office of Biological and Physical Research under grant.

  5. Preparation of dye-adsorbing ZnO thin films by electroless deposition and their photoelectrochemical properties.

    PubMed

    Nagaya, Satoshi; Nishikiori, Hiromasa

    2013-09-25

    Dye-adsorbing ZnO thin films were prepared on ITO films by electroless deposition. The films were formed in an aqueous solution containing zinc nitrate, dimethylamine-borane, and eosin Y at 328 K. The film thickness was 1.2-2.0 μm. Thinner and larger-plane hexagonal columns were produced from the solution containing a higher concentration of eosin Y. A photocurrent was observed in the electrodes containing such ZnO films during light irradiation. The photoelectrochemical performance of the film was improved by increasing the concentration of eosin Y because of increases in the amount of absorbed photons and the electronic conductivity of ZnO. PMID:24020721

  6. Vibrational spectra of CO adsorbed on oxide thin films: A tool to probe the surface defects and phase changes of oxide thin films

    SciTech Connect

    Savara, Aditya

    2014-03-15

    Thin films of iron oxide were grown on Pt(111) single crystals using cycles of physical vapor deposition of iron followed by oxidative annealing in an ultrahigh vacuum apparatus. Two procedures were utilized for film growth of ∼15–30 ML thick films, where both procedures involved sequential deposition+oxidation cycles. In procedure 1, the iron oxide film was fully grown via sequential deposition+oxidation cycles, and then the fully grown film was exposed to a CO flux equivalent to 8 × 10{sup −7} millibars, and a vibrational spectrum of adsorbed CO was obtained using infrared reflection-absorption spectroscopy. The vibrational spectra of adsorbed CO from multiple preparations using procedure 1 show changes in the film termination structure and/or chemical nature of the surface defects—some of which are correlated with another phase that forms (“phase B”), even before enough of phase B has formed to be easily detected using low energy electron diffraction (LEED). During procedure 2, CO vibrational spectra were obtained between deposition+oxidation cycles, and these spectra show that the film termination structure and/or chemical nature of the surface defects changed as a function of sequential deposition+oxidation cycles. The authors conclude that measurement of vibrational spectra of adsorbed CO on oxide thin films provides a sensitive tool to probe chemical changes of defects on the surface and can thus complement LEED techniques by probing changes not visible by LEED. Increased use of vibrational spectra of adsorbed CO on thin films would enable better comparisons between films grown with different procedures and by different groups.

  7. Effect of film thickness on the antifouling performance of poly(hydroxy-functional methacrylates) grafted surfaces.

    PubMed

    Zhao, Chao; Li, Lingyan; Wang, Qiuming; Yu, Qiuming; Zheng, Jie

    2011-04-19

    The development of nonfouling biomaterials to prevent nonspecific protein adsorption and cell/bacterial adhesion is critical for many biomedical applications, such as antithrombogenic implants and biosensors. In this work, we polymerize two types of hydroxy-functional methacrylates monomers of 2-hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA) into polymer brushes on the gold substrate via surface-initiated atom transfer radical polymerization (SI-ATRP). We systematically examine the effect of the film thickness of polyHEMA and polyHPMA brushes on their antifouling performance in a wide range of biological media including single-protein solution, both diluted and undiluted human blood serum and plasma, and bacteria culture. Surface plasmon resonance (SPR) results show a strong correlation between antifouling property and film thickness. Too thin or too thick polymer brushes lead to large protein adsorption. Surfaces with the appropriate film thickness of ∼25-45 nm for polyHPMA and ∼20-45 nm for polyHEMA can achieve almost zero protein adsorption (<0.3 ng/cm(2)) from single-protein solution and diluted human blood plasma and serum. For undiluted human blood serum and plasma, polyHEMA brushes at a film thickness of ∼20-30 nm adsorb only ∼3.0 and ∼3.5 ng/cm(2) proteins, respectively, while polyHPMA brushes at a film thickness of ∼30 nm adsorb more proteins of ∼13.5 and ∼50.0 ng/cm(2), respectively. Moreover, both polyHEMA and polyHPMA brushes with optimal film thickness exhibit very low bacteria adhesion. The excellent antifouling ability and long-term stability of polyHEMA and polyHPMA brushes make them, especially for polyHEMA, effective and stable antifouling materials for usage in blood-contacting devices. PMID:21405141

  8. Scalable Thick-Film Magnetics: Nano Structured Scalable Thick-Film Magnetics

    SciTech Connect

    2011-01-01

    ADEPT Project: Magnetic components are typically the largest components in a power converter. To date, however, researchers haven't found an effective way to reduce their size without negatively impacting their performance. And, reducing the size of the converter's other components isn't usually an option because shrinking them can also diminish the effectiveness of the magnetic components. GE is developing smaller magnetic components for power converters that maintain high performance levels. The company is building smaller components with magnetic films. These films are created using the condensation of a vaporized form of the magnetic material. It's a purely physical process that involves no chemical reactions, so the film composition is uniform. This process makes it possible to create a millimeter-thick film deposition over a wide surface area fairly quickly, which would save on manufacturing costs. In fact, GE can produce 1-10 millimeter-thick films in hours. The magnetic components that GE is developing for this project could be used in a variety of applications, including solar inverters, electric vehicles, and lighting.

  9. Multiplexed Holographic Optical Data Storage In Thick Bacteriorhodopsin Films

    NASA Technical Reports Server (NTRS)

    Downie, John D.; Timucin, Dogan A.; Gary, Charles K.; Ozcan, Meric; Smithey, Daniel T.; Crew, Marshall

    1998-01-01

    The optical data storage capacity of photochromic bacteriorhodopsin films is investigated by means of theoretical calculations, numerical simulations, and experimental measurements on sequential recording of angularly multiplexed diffraction gratings inside a thick D85N BR film.

  10. Selective Gas Capture Ability of Gas-Adsorbent-Incorporated Cellulose Nanofiber Films.

    PubMed

    Shah, Kinjal J; Imae, Toyoko

    2016-05-01

    The 2,2,6,6-tetramethylpiperidine-1-oxyl radical-oxidized cellulose nanofibers (TOCNF) were hybridized with cation and anion-exchange organoclays, where poly(amido amine) dendrimers were loaded to enhance the functionality of gas adsorption, since dendrimers have the high adsorbability and the enough selectivity on the gas adsorption. The thin films were prepared from the organoclay-TOCNF hybrids and supplied to the gas adsorption. The adsorption of CO2 and NH3 gases increased with an increasing amount of organoclays in TOCNF films, but the behavior of the increase depended on gases, clays, and dendrimers. The hydrotalcite organoclay-TOCNF films displayed the highest adsorption of both gases, but the desorption of CO2 gas from hydrotalcite organoclay-TOCNF films was drastically high in comparison with the other systems. While the CO2 gas is adsorbed and remained on cationic dendrimer sites in cation-exchange organoclay-TOCNF films, the CO2 gas is adsorbed on cationic clay sites in anion exchange organoclay-TOCNF films, and it is easily desorbed from the films. The NH3 adsorption is inversive to the CO2 adsorption. Then the CO2 molecules adsorbed on the cationic dendrimers and the NH3 molecules adsorbed on the anionic dendrimers are preferably captured in these adsorbents. The present research incorporated dendrimers will be contributing to the development of gas-specialized adsorbents, which are selectively storable only in particular gases. PMID:27035217

  11. Mesoscopic Hamiltonian for the fluctuations of adsorbed Lennard-Jones liquid films.

    PubMed

    Fernández, Eva M; Chacón, Enrique; MacDowell, Luis G; Tarazona, Pedro

    2015-06-01

    We use Monte Carlo simulations of a Lennard-Jones fluid adsorbed on a short-range planar wall substrate to study the fluctuations in the thickness of the wetting layer, and we get a quantitative and consistent characterization of their mesoscopic Hamiltonian, H[ξ]. We have observed important finite-size effects, which were hampering the analysis of previous results obtained with smaller systems. The results presented here support an appealing simple functional form for H[ξ], close but not exactly equal to the theoretical nonlocal proposal made on the basis a generic density-functional analysis by Parry and coworkers. We have analyzed systems under different wetting conditions, as a proof of principle for a method that provides a quantitative bridge between the molecular interactions and the phenomenology of wetting films at mesoscopic scales. PMID:26172722

  12. Influence of ionic strength changes on the structure of pre-adsorbed salivary films. A response of a natural multi-component layer.

    PubMed

    Macakova, Lubica; Yakubov, Gleb E; Plunkett, Mark A; Stokes, Jason R

    2010-05-01

    Salivary films coating oral surfaces are critically important for oral health. This study focuses on determining the underlying nature of this adsorbed film and how it responds to departures from physiological conditions due to changes in ionic strength. Under physiological conditions, it is found that pre-adsorbed in vitro salivary film on hydrophobic surfaces is present as a highly hydrated viscoelastic layer. We follow the evolution of this film in terms of its effective thickness, hydration and viscoelastic properties, as well as adsorbed mass of proteins, using complementary surface characterisation methods: a Surface Plasmon Resonance (SPR) and a Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D). Our results support a heterogeneous model for the structure of the salivary film with an inner dense anchoring layer and an outer highly extended hydrated layer. Further swelling of the film was observed upon decreasing the salt concentration down to 1mM NaCl. However, upon exposure to deionised water, a collapse of the film occurs that was associated with the loss of water contained within the adsorbed layer. We suggest that the collapse in deionised water is driven by an onset of electrostatic attraction between different parts of the multi-component salivary film. It is anticipated that such changes could also occur when the oral cavity is exposed to food, beverage, oral care and pharmaceutical formulations where drastic changes to the structural integrity of the film is likely to have implications on oral health, sensory perception and product performance. PMID:20133111

  13. Effects of the Adsorbed Polymer Nanolayers on the Dewetting of Polystyrene Thin Films

    NASA Astrophysics Data System (ADS)

    Cheung, Justin; Wang, Jiaxun; Jiang, Naisheng; Endoh, Maya; Koga, Tadanori

    2015-03-01

    It was previously reported that irreversibly adsorbed polymer nanolayers can be produced on solid substrates by thermal annealing. This study sought to determine the impact of the adsorbed nanolayers on film stability of ultrathin polystyrene (PS) films. A series of bilayers composed of the bottom PS adsorbed nanolayers and PS overlayers with different molecular weights were prepared as model systems. The surface structures of the bilayer films annealed above the bulk glass transition temperature were analyzed by using optical and atomic force microscopes. We will discuss the unique roles of the adsorbed polymer chains in the stability of the liquid thin films. T. K. acknowledges the partial financial support from NSF Grant No. CMMI-1332499.

  14. Preparation of Thick Magnet Films by the Aerosol Deposition Method

    NASA Astrophysics Data System (ADS)

    Sugimoto, Satoshi

    The aerosol deposition method (ADM) is effective for the preparation of thick films with high deposition rate. We applied this method to fabricate NiZn ferrite or Sm-Fe-N films, which are used for microwave absorbers or permanent magnets, respectively. In this article, the magnetic properties of Sm-Fe-N thick films fabricated by the ADM are introduced and the possibility of the ADM for the fabrication process with high deposition rate is discussed.

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

    PubMed

    Pongjanyakul, Thaned; Puttipipatkhachorn, Satit

    2008-01-01

    The different film thicknesses of the sodium alginate-magnesium aluminum silicate (SA-MAS) microcomposite films were prepared by varying volumes of the composite dispersion for casting. Effect of film thickness on thermal behavior, solid-state crystallinity, mechanical properties, water uptake and erosion, and water vapor and drug permeability of the microcomposite films were investigated. The film thickness caused a small change in thermal behavior of the films when tested using DSC and TGA. The crystallinity of the thin films seemed to increase when compared with the thick films. The thin films gave higher tensile strength than the thick films, whereas % elongation of the films was on the contrary resulted in the lower Young's modulus of the films when the film thickness was increased. This was due to the weaker of the film bulk, suggesting that the microscopic matrix structure of the thick films was looser than that of the thin films. Consequently, water uptake and erosion, water vapor permeation and drug diffusion coefficient of the thick films were higher than those of the thin films. The different types of drug on permeability of the films also showed that a positive charge and large molecule of drug, propranolol HCl, had higher lag time and lower diffusion coefficient that acetaminophen, a non-electrolyte and small molecule. This was because of a higher affinity of positive charge drug on MAS in the films. The findings suggest that the evaporation rate of solvent in different volumes of the composite dispersion used in the preparation method could affect crystallinity and strength of the film surface and film bulk of the microcomposite films. This led to a change in water vapor and drug permeability of the films. PMID:17611056

  16. NMR Study of Phase Transitions in Pure Water and Binary H(2)O/HNO(3) Films Adsorbed on Surface of Pyrogenic Silica.

    PubMed

    Bogdan; Kulmala; Gorbunov; Kruppa

    1996-01-15

    Pyrogenic silica (aerosil) was employed as host within which the phase transitions in the adsorbed pure water and binary H(2)O/HNO(3) films have been studied with NMR spectroscopy. The median freezing temperature and freezing temperature region were shown to be highly sensitive both to the average thickness of the adsorbed films and to the amount of adsorbed nitric acid. The molar concentration of nitric acid in the adsorbed films was found to be very small, on the order of 10(-3)-10(-2) (M/liter). The concentration was found to be greater in the layers adjacent to the surface of silica and sharply decreases with distance from the surface. The difference between the median freezing temperatures for adsorbed pure water and for the binary system was found to be about 9 K for films of equal thickness. This is about 150 times greater than the difference between the freezing temperatures of bulk pure water and a solution with the same concentration of nitric acid. PMID:10479419

  17. Magic thickness of Bi films on the Si(111) surfac

    NASA Astrophysics Data System (ADS)

    Saito, Mineo; Takahisa, Ohno; Miyazaki, Tsuyoshi

    2004-03-01

    Stable films having specific layer thickness, which is called magic layer thickness, were reported for some metal films on Si(111). The 2D growth is achieved at this thickness; as a result, very flat films are grown. This behavior observed in low temperatures was attributed to the quantum size effect, which originates from the electron confinement in the film thickness direction. Recently the magic layer thickness was observed even at room temperature for Bi films on Si (111) surface, which raises a question as to what is the origin of this prominent stability. To answer this question, we perform first-principle calculation based on the density functional theory within the generalized gradient approximation. We first study 012 Bi film on Si (111) surface. The calculation on the energy difference between the N and N-1 layers shows that the films with even-number layer heights are stable at room temperature. In even-number layer films, each of two layers are found to be bonded. It is concluded that this pairing structure is the origin of the stability at room temperature. Therefore the magic thickness is not due to the quantum size effect. This research was done in "Frontier Simulation Software for Industrial Science" project supported by IT program of Ministry of Education, Culture, Sports, Science and Technology.

  18. Integrated thick-film nanostructures based on spinel ceramics

    PubMed Central

    2014-01-01

    Integrated temperature-humidity-sensitive thick-film structures based on spinel-type semiconducting ceramics of different chemical compositions and magnesium aluminate ceramics were prepared and studied. It is shown that temperature-sensitive thick-film structures possess good electrophysical characteristics in the region from 298 to 358 K. The change of electrical resistance in integrated thick-film structures is 1 order, but these elements are stable in time and can be successfully used for sensor applications. PMID:24670141

  19. Integrated thick-film nanostructures based on spinel ceramics.

    PubMed

    Klym, Halyna; Hadzaman, Ivan; Shpotyuk, Oleh; Brunner, Michael

    2014-01-01

    Integrated temperature-humidity-sensitive thick-film structures based on spinel-type semiconducting ceramics of different chemical compositions and magnesium aluminate ceramics were prepared and studied. It is shown that temperature-sensitive thick-film structures possess good electrophysical characteristics in the region from 298 to 358 K. The change of electrical resistance in integrated thick-film structures is 1 order, but these elements are stable in time and can be successfully used for sensor applications. PMID:24670141

  20. Liquid film thickness measurement by two-line TDLAS

    SciTech Connect

    Yang, Huinan; Chen, Jun; Cai, Xiaoshu; Greszik, Daniel; Dreier, Thomas; Schulz, Christof

    2014-04-11

    A fiber-based two-line tunable diode-laser absorption sensor with two near-infrared (NIR) distributed-feedback (DFB) diode lasers at ∼1.4 μm was used for non-intrusive time-resolved liquid water film thickness measurement. When probing the liquid film at two different wavelengths with significantly different absorption cross-sections, the additional signal losses due to surface fowling, reflection and beam steering can be eliminated. In this work, the evaporation process of a liquid film on transparent quartz plate was tracked and large fluctuations of film thickness were found at the end of the evaporation.

  1. Liquid film thickness measurement by two-line TDLAS

    NASA Astrophysics Data System (ADS)

    Yang, Huinan; Chen, Jun; Cai, Xiaoshu; Greszik, Daniel; Dreier, Thomas; Schulz, Christof

    2014-04-01

    A fiber-based two-line tunable diode-laser absorption sensor with two near-infrared (NIR) distributed-feedback (DFB) diode lasers at ˜1.4 μm was used for non-intrusive time-resolved liquid water film thickness measurement. When probing the liquid film at two different wavelengths with significantly different absorption cross-sections, the additional signal losses due to surface fowling, reflection and beam steering can be eliminated. In this work, the evaporation process of a liquid film on transparent quartz plate was tracked and large fluctuations of film thickness were found at the end of the evaporation.

  2. Direct Measurement of the Adsorbed Film Volume for Estimating Heats of Adsorption

    NASA Astrophysics Data System (ADS)

    Gillespie, Andrew; Dohnke, Elmar; Rash, Tyler; Stalla, David; Knight, Ernest; Seydel, Florian; Sweany, Mark; Pfeifer, Peter

    Compressed hydrogen and methane require extremely high pressures or low temperatures in order to compete with the energy density of conventional fossil fuels. Adsorbent materials provide a means to increase the energy density of these gasses up to 6 times that of compressed gas at the same temperature and pressure. One major concern in engineering adsorbed gas systems is thermal management during charging and discharging. Adsorption is an exothermic process, releasing heat during charging and absorbing heat during discharging. To estimate the heat of adsorption, it is common to analyze excess adsorption isotherms by converting to absolute adsorption and employ the Clausius Clapeyron relation. However, this method requires an assumed volume of the adsorbed state. It is common for researchers to assume that the adsorbed film occupies the entire pore volume of the adsorbent material. However, the adsorbed film only occupies a fraction of the total pore volume. This yields heats of adsorption that are underestimated by as much as 10kJ/mol at high coverage. In this talk, we present a method to directly measure the adsorbed film volume as a function of temperature and present the resulting heats of adsorption for both methane and hydrogen.

  3. Absolute Measurements of Radiation Damage in Nanometer Thick Films

    PubMed Central

    Alizadeh, Elahe; Sanche, Léon

    2013-01-01

    We address the problem of absolute measurements of radiation damage in films of nanometer thicknesses. Thin films of DNA (~ 2–160nm) are deposited onto glass substrates and irradiated with varying doses of 1.5 keV X-rays under dry N2 at atmospheric pressure and room temperature. For each different thickness, the damage is assessed by measuring the loss of the supercoiled configuration as a function of incident photon fluence. From the exposure curves, the G-values are deduced, assuming that X-ray photons interacting with DNA, deposit all of their energy in the film. The results show that the G-value (i.e., damage per unit of deposited energy) increases with film thickness and reaches a plateau at 30±5 nm. This thickness dependence provides a correction factor to estimate the actual G-value for films with thicknesses below 30nm thickness. Thus, the absolute values of damage can be compared with that of films of any thickness under different experimental conditions. PMID:22562941

  4. Modeling parameter extraction for DNQ-novolak thick film resists

    NASA Astrophysics Data System (ADS)

    Henderson, Clifford L.; Scheer, Steven A.; Tsiartas, Pavlos C.; Rathsack, Benjamen M.; Sagan, John P.; Dammel, Ralph R.; Erdmann, Andreas; Willson, C. Grant

    1998-06-01

    Optical lithography with special thick film DNQ-novolac photoresists have been practiced for many years to fabricate microstructures that require feature heights ranging from several to hundreds of microns such as thin film magnetic heads. It is common in these thick film photoresist systems to observe interesting non-uniform profiles with narrow regions near the top surface of the film that transition into broader and more concave shapes near the bottom of the resist profile. A number of explanations have been proposed for these various observations including the formation of `dry skins' at the resist surface and the presence of solvent gradients in the film which serve to modify the local development rate of the photoresist. There have been few detailed experimental studies of the development behavior of thick films resists. This has been due to part to the difficulty in studying these films with conventional dissolution rate monitors (DRMs). In general, this lack of experimental data along with other factors has made simulation and modeling of thick film resist performance difficult. As applications such as thin film head manufacturing drive to smaller features with higher aspect ratios, the need for accurate thick film simulation capability continues to grow. A new multi-wavelength DRM tool has been constructed and used in conjunction with a resist bleaching tool and rigorous parameter extraction techniques to establish exposure and development parameters for two thick film resists, AZTM 4330-RS and AZTM 9200. Simulations based on these parameters show good agreement to resist profiles for these two resists.

  5. Influence of Chemical Composition on the Reaction Products Observed During Electron Stimulated Decomposition of Organohalides Adsorbed in Water (Ice) Films

    NASA Astrophysics Data System (ADS)

    Fairbrother, Howard; Perry, Christopher; Faradzhev, Nadir; Madey, Theodore

    2004-03-01

    We report on the reactions of CF_2Cl2 and other organohalides codeposited_ in water (ice) films (≈100 nm thick on Au) at ˜ 100K during X-ray or electron beam irradiation. X-ray irradiation produces a distribution of low energy secondary electrons that in CF_2Cl_2/H_2O(ice) films produce H_3O^+, CO2 and COF2 (carbonyl fluoride). Chloride and fluoride anions are also produced and solvated (trapped) within the ice film during X-ray or electron irradiation. Product partitioning is dependent on the film's chemical composition; in water rich films, CO2 and COF2 production is favored, while a thermally stable partially halogenated CF_xCly film is detected in CF_2Cl2 rich films. During the early stages of irradiation, the dominance of Cl^- anions indicates that DEA of CF_2Cl2 via C-Cl cleavage (CF_2Cl2 + e^- → ot CF_2Cl + Cl^-) is the primary initial process. These results obtained for CF_2Cl2 are compared with electron stimulated reactions of other organohalides (CCl_4, CDCl_3, CD_2Cl2 and CH_3I) adsorbed in water(ice)films.

  6. Critical thickness for the agglomeration of thin metal films

    SciTech Connect

    Boragno, C.; Buatier de Mongeot, F.; Felici, R.; Robinson, I.K.

    2009-09-15

    A thin metal film can exist in a metastable state with respect to breaking into small clusters. In this paper we report on grazing incidence small-angle x-ray scattering studies carried out in situ during the annealing of thin Ni films, between 2 and 10 nm thick, deposited on an amorphous SiO{sub 2} substrate. Our results show the presence of two different regimes which depend on the initial film thickness. For thicknesses less than 5 nm the annealing results in the formation of small, compact clusters on top of a residual Ni wetting layer. For thicknesses greater than 5 nm the film breaks into large, well-separated clusters and the substrate shows an uncovered clean surface.

  7. Improved thick film semiconductor/solar cell contacts

    NASA Technical Reports Server (NTRS)

    Ross, B.

    1979-01-01

    The postulated concept of low-temperature all-metal thick film electrodes is discussed. It is noted that the mechanical and metallurgical properties of the electrodes are excellent, but electrical parameters remain to be optimized.

  8. Raman spectroscopy and microstructure of the pulsed laser-treated silver-anatase thick film

    NASA Astrophysics Data System (ADS)

    Joya, Yasir F.; Joya, K. S.; Bashir, S.; Anwar, A. W.; Rafique, M. S.; Ahmed, Riaz

    2015-09-01

    The present research describes the effect of laser pulses on crystalline titanium dioxide thick film with self-adsorbed silver ions. Anatase film of up to 4 µm thickness was deposited on ITO glass by doctor-blading technique. The film was heated at 450 °C for 60 min and cooled before immersion in silver nitrate aqueous solution. After drying, films were subjected to nanosecond pulses of the excimer laser, and their structural, microstructural and optical properties were investigated. Scanning electron microscopy and EDX analysis revealed the formation of silver nanoparticles (SNPs) dispersed in the anatase matrix. There was no significant change in the anatase structure as revealed by Raman spectroscopy. The intensity of Raman signals from pristine anatase film was increased after the laser treatment of silver ions on the film. This observation is associated with the phenomenon of localized surface plasmon resonance conferred by the crystalline SNPs. The results obtained by the UV-visible spectroscopy also support the role of SNPs to enhance the photoabsorption of the anatase film in the visible region.

  9. Microfluidic devices with thick-film electrochemical detection

    DOEpatents

    Wang, Joseph; Tian, Baomin; Sahlin, Eskil

    2005-04-12

    An apparatus for conducting a microfluidic process and analysis, including at least one elongated microfluidic channel, fluidic transport means for transport of fluids through the microfluidic channel, and at least one thick-film electrode in fluidic connection with the outlet end of the microfluidic channel. The present invention includes an integrated on-chip combination reaction, separation and thick-film electrochemical detection microsystem, for use in detection of a wide range of analytes, and methods for the use thereof.

  10. Piston ring oil film thickness-The effect of viscosity

    SciTech Connect

    Moore, S.L.

    1985-01-01

    A Petter AV1 diesel engine has been modified to operate as a crosshead engine with a separate lubricant supply to the piston rings. Measurements of the minimum oil film thickness between the rings and the liner are presented for both mono-grade and multi-grade oils. It is shown that, at top-dead-centre, the film thickness increases as the viscosity is reduced.

  11. Thick, low-stress films, and coated substrates formed therefrom

    DOEpatents

    Henager, Jr., Charles H.; Knoll, Robert W.

    1991-01-01

    Stress-induced deformation, and the damage resulting therefrom, increases with film thickness. The overcoming of excessive stress by the use of the film material of the present invention, permits the formation of thick films that are necessary for certain of the above described applications. The most likely use for the subject film materials, other than their specialized views as an optical film, is for microelectronic packaging of components on silicon substrates. In general, the subject Si-Al-O-N films have excellent adherence to the underlying substrate, a high degree of hardness and durability, and are excellent insulators. Prior art elevated temperature deposition processes cannot meet the microelectronic packaging temperature formation constraints. The process of the present invention is conducted under non-elevated temperature conditions, typically 500# C. or less.

  12. Thick-Film Yttrium Iron Garnet Coatings via Aerosol Deposition

    NASA Astrophysics Data System (ADS)

    Johnson, Scooter D.; Glaser, Evan R.; Cheng, Shu-Fan; Eddy, Charles R.; Kub, Fritz; Gorzkowski, Edward P.

    2016-03-01

    Aerosol deposition is a thick-film deposition process that can produce layers up to several hundred micrometers thick with densities greater than 95 pct of the theoretical value. The primary advantage of aerosol deposition is that the deposition takes place entirely at room temperature, thereby enabling film growth in material systems with disparate melting temperatures. We show representative characterization results of yttrium iron garnet thick films deposited onto a <111> gadolinium gallium garnet substrate by aerosol deposition using scanning electron microscopy, X-ray diffraction, profilometry, vibrating sample magnetometry, and ferromagnetic resonance. To further elucidate the effect of density and grain size on the magnetic properties, we perform post-deposition annealing of the films to study the effect on the structural and magnetic properties of the films. Our results indicate that our system can successfully deposit dense, thick yttrium iron garnet films and that with moderate annealing the films can achieve a ferromagnetic resonance linewidth comparable to that reported for polycrystalline films deposited by other higher temperature growth techniques.

  13. Method of measuring the thickness of radioactive thin films

    NASA Technical Reports Server (NTRS)

    Alger, D. L.; Steinberg, R.; Makinen, M. D.

    1974-01-01

    Thickness monitor consists of proportional X-ray counter coupled to pulse counting system, copper filter over face of counter, rotatable collimator containing radioactive source, and rotatable shutter. Monitor can be used as integral part of neutron generator. It has been used to measure titanium tritide film thicknesses from 0.1 to 30 micrometers.

  14. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    SciTech Connect

    Kenny, T.W.

    1989-05-01

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of /sup 4/He adsorbed on metallic films. In contrast to measurements of /sup 4/He adsorbed on all other insulating substrates, we have shown that /sup 4/He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, /sup 4/He adsorbed on sapphire and on Ag films and H/sub 2/ adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs.

  15. Glue Film Thickness Measurements by Spectral Reflectance

    SciTech Connect

    B. R. Marshall

    2010-09-20

    Spectral reflectance was used to determine the thickness of thin glue layers in a study of the effect of the glue on radiance and reflectance measurements of shocked-tin substrates attached to lithium fluoride windows. Measurements based on profilometry of the components were found to be inaccurate due to flatness variations and deformation of the tin substrate under pressure during the gluing process. The accuracy of the spectral reflectance measurements were estimated to be ±0.5 μm, which was sufficient to demonstrate a convincing correlation between glue thickness and shock-generated light.

  16. Effect of Temperature Gradient on Thick Film Selective Emitter Emittance

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Good, Brian S.; Clark, Eric B.; Chen, Zheng

    1997-01-01

    A temperature gradient across a thick (greater than or equal to .1 mm) film selective emitter will produce a significant reduction in the spectral emittance from the no temperature gradient case. Thick film selective emitters of rare earth doped host materials such as yttrium-aluminum-garnet (YAG) are examples where temperature gradient effects are important. In this paper a model is developed for the spectral emittance assuming a linear temperature gradient across the film. Results of the model indicate that temperature gradients will result in reductions the order of 20% or more in the spectral emittance.

  17. Solar Sail Interstellar Travel - 1. Thickness of Solar Sail Films

    NASA Astrophysics Data System (ADS)

    Ya Kezerashvili, R.

    An exploration of the outer solar system using solar sail propulsion with high cruise speed requires an acceleration of the sail craft in the near-Sun space region. When spacecraft approaches the Sun there are at least two important factors that have an effect on the thickness of solar sail film and therefore on the reflection ability of the sail: the temperature dependence of electrical conductivity of sail material and existence of a wide range of solar electromagnetic radiation frequencies. Applying the system of Maxwell's equations for linear conducting media the minimum film thickness that provides the maximum reflectance is found and dependence of this minimum thickness on temperature as well as on electromagnetic spectrum of solar radiation is investigated. It is shown that temperature dependence of the conductivity of the film under a constant temperature coefficient of conductivity requires an increase of the thickness of the solar sail by a factor 2 to 3. Consideration of the temperature coefficient of conductivity dependence on temperature also requires an increase of film thickness by more than 35% at high temperatures. When the frequency dependence of the conductivity is taken into account the minimal thickness of the solar sail film increases significantly (almost by a factor of 4), but at the same time exhibits the negligible dependence on the wavelength. We suggest that these factors should be taken into consideration in the solar sail design.

  18. Noninvasive thickness measurements of metal films through microwave dielectric resonators

    NASA Astrophysics Data System (ADS)

    Jung, Ho Sang; Lee, Jae Hun; Han, Hyun Kyung; Lee, Sang Young

    2016-05-01

    Thicknesses of Pt films ranging from 60 to 950 nm are measured noninvasively using a TE 011-mode dielectric resonator with the resonant frequency of 8.5 - 9.8 GHz at temperatures of 77 K and 293 K. A cylindrical rutile rod is used as the dielectric, with a high- T C superconductive YBa2Cu3O7- δ film used as the bottom endplate of the resonator for measurements at 77 K. This method is based on two facts: i) Due to the electromagnetic interferences of incoming and reflected waves at the surface of the metal film surface, the effective surface resistance varies with the film thickness, and ii) the intrinsic surface resistance of normal metals is equal to the intrinsic surface reactance in the local limit. The measured thicknesses using the rutile resonator appear to be comparable with those obtained using a profilometer. [Figure not available: see fulltext.

  19. O the Transition from - to Three-Dimensional Behavior in Adsorbed Films

    NASA Astrophysics Data System (ADS)

    Day, Peter Kenneth

    1993-01-01

    Argon and krypton films adsorbed on graphite foam have been studied in detail using vapor pressure and high resolution, heat capacity measurements. Heat capacity features near the bulk triple point temperature, previously associated with the surface melting of the uniform film, are shown to be due to the melting of bulk material condensed in pores in the substrate. The melting curve of the capillary condensate agrees with the prediction of a modified Clausius -Claperon equation. The second and third layers in argon and the second layer in krypton have a triple point at which two-dimensional solid, liquid, and gas phases coexist atop a solid lower layer. Commensurate-incommensurate transitions are found in the first two layers of argon and in the second layer of krypton, so that monolayer argon melts from a registered phase, but the second layers of both systems melt from incommensurate bilayer phases. The melting of the second and third layers in both systems are likely to be first order, but the data are not conclusive. At coverages starting with 3{1over 2} layers, heat capacity features that are due to reentrant layering-transitions are seen in both systems, confirming the result of recent ellipsometry studies. Further heat capacity peaks suggest phase transitions that join the newly observed reentrant layering-transitions with the well studied layering-transitions at low temperature. These heat capacity peaks may be related to the recently proposed preroughening transition. A mean field theory is developed that reproduced the reentrant layering behavior for ratios of nearest and next nearest neighbor interaction energies greater than a critical value. The mean field theory gives an explanation for the appearance of reentrant layering -transitions at different film thicknesses depending on the substrate-adsorbate interaction parameter. Multilayer phase diagrams are drawn from the data that suggest a crossover from two-dimensional behavior in the second layer to

  20. Characterization of a nanometer-thick sputtered polytetrafluoroethylene film

    NASA Astrophysics Data System (ADS)

    Li, Lei; Jones, Paul M.; Hsia, Yiao-Tee

    2011-02-01

    Fast growth of nanotechnology, e.g. hard disk drive (HDD) and microelectromechanical system/nanoelectromechanical system (MEMS/NEMS), requires nanometer-thick protection films with high thermal stability and low surface energy. In this paper, we report the characterization results of a nanometer-thick sputtered polytetrafluoroethylene (PTFE) film prepared by radio frequency (RF) sputtering. Atomic force microscopy (AFM) and X-ray reflectivity (XRR) results show that the nanometer-thick sputtered PTFE film has good uniformity. Thermally programmed desorption (TPD) results show that the film is thermally stable up to 430 °C. Surface energy measurement via contact angle method shows that the film has low surface energy with the thickness as low as 1.5 nm. X-ray photoelectron spectroscopy (XPS) data suggests that the film has crosslinked molecular structure, which results in amorphous morphology as shown by X-ray diffraction (XRD) data. Nano-indentation testing shows that the sputtered film has higher hardness and modulus than bulk PTFE. The structure-property relationship has been discussed.

  1. Development of the nitride film thickness standard (NFTS)

    NASA Astrophysics Data System (ADS)

    Durga Pal, Prabha

    1998-07-01

    The semiconductor industry has been demanding film thickness reference material for films other than thermally grown silicon dioxide for sometime. To meet this challenge, Nitride Film Thickness Standard (NFTS) has been developed in four nominal thickness values, 20.0 nm, 90.0 nm, 120.0 nm and 200.0 nm. These are silicon nitride (Si3N4) films on silicon crystal substrate. Work is underway to develop a 9.0 nm standard. Thin nitride films are particularly needed for calibration of the thickness of nitride layers in capacitors and isolation masks for LOCOS (local oxidation of silicon). The reference material is certified for derived film thickness. The study consists of measurements made on four different sets of wafers that included patterned and unpatterned wafers. The measurements made on these wafer sets were used for answering issues related to film stability and cleaning. The stability study includes the search for a cleaning process that will restore a prior surface condition. On two sets of wafers two different types of cleaning procedures were used. Results indicate that a sulfuric acidmegasonic clean will etch the nitride film while an isopropyl alcohol clean followed by a deionized water rinse can be used over and over again. The third set of wafers was never cleaned and measurements were made on these over a period of two years. The last set of wafers is patterned. These are cleaned prior to measurement. Results show that LPCVD silicon nitride films are stable and can be used with confidence over a long period of time for calibrating optical metrology instruments.

  2. 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.

  3. Measuring sub-nm adsorbed water layer thickness and desorption rate using a fused-silica whispering-gallery microresonator

    NASA Astrophysics Data System (ADS)

    Ganta, D.; Dale, E. B.; Rosenberger, A. T.

    2014-05-01

    We report an optical method for measuring the thickness of the water layer adsorbed onto the surface of a high-Q fused-silica microresonator. Light from a tunable diode laser operating near 1550 nm is coupled into the microresonator to excite whispering-gallery modes (WGMs). By observing thermal distortion or even bistability of the WGM resonances caused by absorption in the water layer, the contribution of that absorption to the total loss is determined. Thereby, the thickness of the water layer is found to be ˜0.1 nm (approximately one monolayer). This method is further extended to measure the desorption rate of the adsorbed water, which is roughly exponential with a decay time of ˜40 h when the fused-silica microresonator is held in a vacuum chamber at low pressure.

  4. Thickness determination of molecularly thin lubricant films by angle-dependent X-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Pang, Chongjun; Bai, Mingwu

    2007-03-01

    An angle-dependent X-ray photoelectron spectroscopy (XPS) method used to measure the thickness of molecularly thin lubricants was developed. The method was built based on an island model of patched overlayer on a flat substrate by using the photoemission signal solely from the lubricant film. Typical molecularly thin Zdol films on the CHx overcoat of unused commercial magnetic disks were measured to verify the metrology. The lubricant thickness determined by the metrology was equal to the recent result by thermostatic high vacuum atomic force microscopy. The measured deduction in the thickness of the molecularly thin lubricant films, successively irradiated by the monochromatic source operated at 14 kV/250 W, was as low as 1 Ǻ during the first irradiation hour. XPS spectra showed that no hydrocarbons, water or oxygen were adsorbed over the Zdol outer surfaces in the tested XPS conditions. The inelastic mean free path (IMFP) of C 1s in Zdol or in CHx was found to be independent of take off angle (TOA) when TOA < 40°. The IMFP of C 1s in Zdol was ˜63.5 Ǻ and the lubricant island thickness was ˜35 Ǻ.

  5. Thickness of residual wetting film in liquid-liquid displacement

    NASA Astrophysics Data System (ADS)

    Beresnev, Igor; Gaul, William; Vigil, R. Dennis

    2011-08-01

    Core-annular flow is common in nature, representing, for example, how streams of oil, surrounded by water, move in petroleum reservoirs. Oil, typically a nonwetting fluid, tends to occupy the middle (core) part of a channel, while water forms a surrounding wall-wetting film. What is the thickness of the wetting film? A classic theory has been in existence for nearly 50 years offering a solution, although in a controversial manner, for moving gas bubbles. On the other hand, an acceptable, experimentally verified theory for a body of one liquid flowing in another has not been available. Here we develop a hydrodynamic, testable theory providing an explicit relationship between the thickness of the wetting film and fluid properties for a blob of one fluid moving in another, with neither phase being gas. In its relationship to the capillary number Ca, the thickness of the film is predicted to be proportional to Ca2 at lower Ca and to level off at a constant value of ˜20% the channel radius at higher Ca. The thickness of the film is deduced to be approximately unaffected by the viscosity ratio of the fluids. We have conducted our own laboratory experiments and compiled experimental data from other studies, all of which are mutually consistent and confirm the salient features of the theory. At the same time, the classic law, originally deduced for films surrounding moving gas bubbles but often believed to hold for liquids as well, fails to explain the observations.

  6. Changes in the temperature-dependent specific volume of supported polystyrene films with film thickness.

    PubMed

    Huang, Xinru; Roth, Connie B

    2016-06-21

    Recent studies have measured or predicted thickness-dependent shifts in density or specific volume of polymer films as a possible means of understanding changes in the glass transition temperature Tg(h) with decreasing film thickness with some experimental works claiming unrealistically large (25%-30%) increases in film density with decreasing thickness. Here we use ellipsometry to measure the temperature-dependent index of refraction of polystyrene (PS) films supported on silicon and investigate the validity of the commonly used Lorentz-Lorenz equation for inferring changes in density or specific volume from very thin films. We find that the density (specific volume) of these supported PS films does not vary by more than ±0.4% of the bulk value for film thicknesses above 30 nm, and that the small variations we do observe are uncorrelated with any free volume explanation for the Tg(h) decrease exhibited by these films. We conclude that the derivation of the Lorentz-Lorenz equation becomes invalid for very thin films as the film thickness approaches ∼20 nm, and that reports of large density changes greater than ±1% of bulk for films thinner than this likely suffer from breakdown in the validity of this equation or in the difficulties associated with accurately measuring the index of refraction of such thin films. For larger film thicknesses, we do observed small variations in the effective specific volume of the films of 0.4 ± 0.2%, outside of our experimental error. These shifts occur simultaneously in both the liquid and glassy regimes uniformly together starting at film thicknesses less than ∼120 nm but appear to be uncorrelated with Tg(h) decreases; possible causes for these variations are discussed. PMID:27334190

  7. Changes in the temperature-dependent specific volume of supported polystyrene films with film thickness

    NASA Astrophysics Data System (ADS)

    Huang, Xinru; Roth, Connie B.

    2016-06-01

    Recent studies have measured or predicted thickness-dependent shifts in density or specific volume of polymer films as a possible means of understanding changes in the glass transition temperature Tg(h) with decreasing film thickness with some experimental works claiming unrealistically large (25%-30%) increases in film density with decreasing thickness. Here we use ellipsometry to measure the temperature-dependent index of refraction of polystyrene (PS) films supported on silicon and investigate the validity of the commonly used Lorentz-Lorenz equation for inferring changes in density or specific volume from very thin films. We find that the density (specific volume) of these supported PS films does not vary by more than ±0.4% of the bulk value for film thicknesses above 30 nm, and that the small variations we do observe are uncorrelated with any free volume explanation for the Tg(h) decrease exhibited by these films. We conclude that the derivation of the Lorentz-Lorenz equation becomes invalid for very thin films as the film thickness approaches ˜20 nm, and that reports of large density changes greater than ±1% of bulk for films thinner than this likely suffer from breakdown in the validity of this equation or in the difficulties associated with accurately measuring the index of refraction of such thin films. For larger film thicknesses, we do observed small variations in the effective specific volume of the films of 0.4 ± 0.2%, outside of our experimental error. These shifts occur simultaneously in both the liquid and glassy regimes uniformly together starting at film thicknesses less than ˜120 nm but appear to be uncorrelated with Tg(h) decreases; possible causes for these variations are discussed.

  8. Optimum Thickness of Sn Film for Whisker Growth

    NASA Astrophysics Data System (ADS)

    Cheng, Jing; Yang, Fuqian; Vianco, Paul T.; Zhang, Bei; Li, James C. M.

    2011-10-01

    By depositing different thicknesses of Sn films over a silicon wafer precoated with Cr and Ni adhesion layers and then by bending the tinned wafer using a dead load applied at the center to introduce the same compressive stresses in the Sn films, the growth rate of whiskers appeared to have a maximum for a certain thickness. This is explained by assuming the Sn atoms to flow along the vertical grain boundaries (perpendicular to the interface) into the interface between Sn and Ni and then along the interface to the root of the whisker through some more vertical grain boundaries. The resistance along the vertical grain boundaries appeared to control the rate of whisker growth for thick films.

  9. Thick-film materials for silicon photovoltaic cell manufacture

    NASA Technical Reports Server (NTRS)

    Field, M. B.

    1977-01-01

    Thick film technology is applicable to three areas of silicon solar cell fabrication; metallization, junction formation, and coating for protection of screened ohmic contacts, particularly wrap around contacts, interconnection and environmental protection. Both material and process parameters were investigated. Printed ohmic contacts on n- and p-type silicon are very sensitive to the processing parameters of firing time, temperature, and atmosphere. Wrap around contacts are easily achieved by first printing and firing a dielectric over the edge and subsequently applying a low firing temperature conductor. Interconnection of cells into arrays can be achieved by printing and cofiring thick film metal pastes, soldering, or with heat curing conductive epoxies on low cost substrates. Printed (thick) film vitreous protection coatings do not yet offer sufficient optical uniformity and transparency for use on silicon. A sprayed, heat curable SiO2 based resin shows promise of providing both optical matching and environmental protection.

  10. Optical coherence tomography as film thickness measurement technique

    NASA Astrophysics Data System (ADS)

    Manallah, Aissa; Bouafia, Mohamed; Meguellati, Said

    2015-01-01

    Optical coherence tomography (OCT) is a powerful optical method, noninvasive and noncontact diagnostic method. Although it is usually used for medical examinations, particularly in ocular exploration; it can also be used in optical metrology as measure technique. In this work, we use OCT to measure thicknesses of films. In OCT, depth profiles are constructed by measuring the time delay of back reflected light by interferometry measurements. Frequency in k-space is proportional to optical path difference. Then the reflectivity profile is obtained by a Fourier transformation, and the difference between two successive peaks of the resulting spectrum gives the film thickness. Several films, food-type, of different thicknesses were investigated and the results were very accurate.

  11. Influence of film thickness on laser ablation threshold of transparent conducting oxide thin-films

    NASA Astrophysics Data System (ADS)

    Rung, S.; Christiansen, A.; Hellmann, R.

    2014-06-01

    We report on a comprehensive study of the laser ablation threshold of transparent conductive oxide thin films. The ablation threshold is determined for both indium tin oxide and gallium zinc oxide as a function of film thickness and for different laser wavelengths. By using a pulsed diode pumped solid state laser at 1064 nm, 532 nm, 355 nm and 266 nm, respectively, the relationship between optical absorption length and film thickness is studied. We find that the ablation threshold decreases with increasing film thickness in a regime where the absorption length is larger than the film thickness. In turn, the ablation threshold increases in case the absorption length is smaller than the film thickness. In particular, we observe a minimum of the ablation threshold in a region where the film thickness is comparable to the absorption length. To the best of our knowledge, this behaviour previously predicted for thin metal films, has been unreported for all three regimes in case of transparent conductive oxides, yet. For industrial laser scribing processes, these results imply that the efficiency can be optimized by using a laser where the optical absorption length is close to the film thickness.

  12. Inhomogeneous Growth of Micrometer Thick Plasma Polymerized Films.

    PubMed

    Akhavan, Behnam; Menges, Bernhard; Förch, Renate

    2016-05-17

    Plasma polymerization is traditionally recognized as a homogeneous film-forming technique. It is nevertheless reasonable to ask whether micrometer thick plasma polymerized structures are really homogeneous across the film thickness. Studying the properties of the interfacial, near-the-substrate (NTS) region in plasma polymer films represents particular experimental challenges due to the inaccessibility of the buried layers. In this investigation, a novel non-destructive approach has been utilized to evaluate the homogeneity of plasma polymerized acrylic acid (PPAc) and 1,7-octadiene (PPOD) films in a single measurement. Studying the variations of refractive index throughout the depth of the films was facilitated by a home-built surface plasmon resonance (SPR)/optical waveguide (OWG) spectroscopy setup. It has been shown that the NTS layer of both PPAc and PPOD films exhibits a significantly lower refractive index than the bulk of the film that is believed to indicate a higher concentration of internal voids. Our results provide new insights into the growth mechanisms of plasma polymer films and challenge the traditional view that considers plasma polymers as homogeneous and continuous structures. PMID:27111265

  13. Performance of supercapacitor with electrodeposited ruthenium oxide film electrodes—effect of film thickness

    NASA Astrophysics Data System (ADS)

    Park, Bong-Ok; Lokhande, C. D.; Park, Hyung-Sang; Jung, Kwang-Deog; Joo, Oh-Shim

    Thin-film ruthenium oxide electrodes are prepared by cathodic electrodeposition on a titanium substrate. Different deposition periods are used to obtain different film thicknesses. The electrodes are used to form a supercapacitor with a 0.5 M H 2SO 4 electrolyte. The specific capacitance and charge-discharge periods are found to be dependent on the electrode thickness. A maximum specific capacitance of 788 F g -1 is achieved with an electrode thickness of 0.0014 g cm -2. These results are explained by considering the morphological changes that take place with increasing film thickness.

  14. Turbulence in Flowing Soap Films: Velocity, Vorticity, and Thickness Fields

    SciTech Connect

    Rivera, M.; Vorobieff, P.; Ecke, R.E.

    1998-08-01

    We report experimental measurements of the velocity, vorticity, and thickness fields of turbulent flowing soap films using a modified particle-image velocimetry technique. These data yield the turbulent energy and enstrophy of the two-dimensional flows with microscale Reynolds numbers of about 100 and demonstrate the effects of compressibility arising from variations in film thickness. Despite the compressibility of the flow, real-space correlations of velocity, vorticity, and enstrophy flux are consistent with theoretical predictions for two-dimensional turbulence. {copyright} {ital 1998} {ital The American Physical Society }

  15. Process for manufacture of thick film hydrogen sensors

    DOEpatents

    Perdieu, Louisa H.

    2000-09-09

    A thick film process for producing hydrogen sensors capable of sensing down to a one percent concentration of hydrogen in carrier gasses such as argon, nitrogen, and air. The sensor is also suitable to detect hydrogen gas while immersed in transformer oil. The sensor includes a palladium resistance network thick film printed on a substrate, a portion of which network is coated with a protective hydrogen barrier. The process utilizes a sequence of printing of the requisite materials on a non-conductive substrate with firing temperatures at each step which are less than or equal to the temperature at the previous step.

  16. Orientations of Diblock Copolymer Microdomains at Different Film Thicknesses

    NASA Astrophysics Data System (ADS)

    Chaikin, Paul; Park, Miri; Harrison, Christopher; Register, Richard; Adamson, Doug

    1996-03-01

    We prepared films with a range of thicknesses (50-300 nm) of a styrene-butadiene diblock copolymer, synthesized to produce a cylindrical morphology. Solutions of different polymer concentrations in toluene were spun onto carbon-coated glass slides. The films were then placed onto a Transmission Electron Microscope (TEM) grid by water lift-off, annealed, stained with osmium tetraoxide, and examined with a TEM. Over a wide range of film thicknesses, the cylinders lie parallel to the substrate. We present preliminary results that show a cylinder orientation perpendicular to the substrate at a thickness of many microdomain spacings. We speculate that the alignment mechanism is different from that found in a previous study of Kraton D1102(M. A. van Dijk and R. van den Berg, Macromolecules 28), 6773 (1995) which shows a perpendicular orientation with spin-coated films, but for a film thickness between one and two microdomain spacings. This work was supported by the NSF under DMR 9400362.

  17. Film thickness frequency distribution of different vehicles determines sunscreen efficacy

    NASA Astrophysics Data System (ADS)

    Sohn, Myriam; Hêche, Adeline; Herzog, Bernd; Imanidis, Georgios

    2014-11-01

    Sun protection factor (SPF) frequently differs between sunscreens containing the same composition of ultraviolet (UV) filters that primarily define sunscreen efficacy. We tested the hypothesis that the thickness frequency distribution of the sunscreen film is also responsible for and can explain the divergence in the measured SPF. For this, we developed a method to measure film thickness from the difference of topography before and after application of 2 mg/cm2 of sunscreen on pig ear epidermal membrane. The influence of five vehicle formulations and of application pressure and spreading time on mean thickness (S), S to median ratio, and SPF in vitro was investigated. The vehicle had a significant impact, low vehicle viscosity resulting in a smaller S, larger S to median ratio, and lower SPF in vitro than high viscosity; continuous oil phase produced the largest S and SPF values. A long spreading time reduced S and SPF and increased application pressure reduced SPF. There was a positive correlation between S and SPF in vitro, underlining the relevance of film thickness for interpreting UV protection differences of formulations with the same filter composition. This work demonstrated a strong influence of vehicle and application conditions on sunscreen efficacy arising from differences in film thickness distribution.

  18. Thin dielectric film thickness determination by advanced transmission electron microscopy

    SciTech Connect

    Diebold, A.C.; Foran, B.; Kisielowski, C.; Muller, D.; Pennycook, S.; Principe, E.; Stemmer, S.

    2003-09-01

    High Resolution Transmission Electron Microscopy (HR-TEM) has been used as the ultimate method of thickness measurement for thin films. The appearance of phase contrast interference patterns in HR-TEM images has long been confused as the appearance of a crystal lattice by non-specialists. Relatively easy to interpret crystal lattice images are now directly observed with the introduction of annular dark field detectors for scanning TEM (STEM). With the recent development of reliable lattice image processing software that creates crystal structure images from phase contrast data, HR-TEM can also provide crystal lattice images. The resolution of both methods was steadily improved reaching now into the sub Angstrom region. Improvements in electron lens and image analysis software are increasing the spatial resolution of both methods. Optimum resolution for STEM requires that the probe beam be highly localized. In STEM, beam localization is enhanced by selection of the correct aperture. When STEM measurement is done using a highly localized probe beam, HR-TEM and STEM measurement of the thickness of silicon oxynitride films agree within experimental error. In this paper, the optimum conditions for HR-TEM and STEM measurement are discussed along with a method for repeatable film thickness determination. The impact of sample thickness is also discussed. The key result in this paper is the proposal of a reproducible method for film thickness determination.

  19. Effects of particle size distribution in thick film conductors

    NASA Technical Reports Server (NTRS)

    Vest, R. W.

    1983-01-01

    Studies of particle size distribution in thick film conductors are discussed. The distribution of particle sizes does have an effect on fired film density but the effect is not always positive. A proper distribution of sizes is necessary, and while the theoretical models can serve as guides to selecting this proper distribution, improved densities can be achieved by empirical variations from the predictions of the models.

  20. Measuring Thicknesses Of Vacuum-Deposited Organic Thin Films

    NASA Technical Reports Server (NTRS)

    David, Carey E.

    1996-01-01

    Method of measuring thickness of thin organic liquid film deposited in vacuum involves use of quartz-crystal monitor (QCM) calibrated by use of witness plate that has, in turn, calibrated by measurement of absorption of infrared light in deposited material. Present procedure somewhat tedious, but once calibration accomplished, thicknesses of organic liquid deposits monitored in real time and in situ by use of QCM.

  1. Acoustic Techniques for Thin Film Thickness Measurement in Semiconductor Processing

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Sanjay

    In modern semiconductor manufacturing, process monitoring and control are important issues limited at the present time by a lack of sensors and instrumentation capable of measuring process parameters like film thickness. In order to address this problem, two novel systems for thin film thickness measurement in semiconductor processing based upon contacting acoustic techniques have been developed. Both of these systems couple acoustic energy into the wafer via a nondestructive Hertzian contact and achieve high resolution by exciting and receiving ultrasonic signals from a ZnO transducer with microwave frequency electronics. The basic physical mechanism for film thickness determination is to analyze reflected waves due to acoustic impedance mismatches between various material layers on a silicon substrate. The first system requires frontside contacting of a sapphire buffer rod to an opaque film deposited on a silicon wafer and involves the use of broadband, high frequency pulse-echo electronics in the 0.5-5 GHz range. With this system, ex-situ measurements of aluminum and gold thin films on a silicon substrate have been done in the 0.25-2.5 mum. range with 3-6% accuracy as compared to surface profilometer measurements. Possible applications for this system include using it as a post -deposition process monitor, generating film thickness contour maps, or examining multilayer structures. The second system requires backside contacting of a sapphire buffer rod to a silicon wafer, which is in a vacuum station, and involves monitoring the changes in phase of CW 1-2 GHz acoustic waves as a function of frontside film growth. Using this technique, in-situ indium and aluminum film thickness monitoring has been done in both evaporator and sputtering environments with a resolution of 40 A. Temperature experiments in an oven have shown a resolution of 0.05 K for the sapphire buffer rod. Finally, multistep processing has been done and a multilayer film structure has been measured

  2. Adsorbate-induced demagnetization and restructuring of ultrathin magnetic films: CO chemisorbed on γ-Fe/Cu(100)

    NASA Astrophysics Data System (ADS)

    Spišák, D.; Hafner, J.

    2001-09-01

    First-principles local-spin-density (LSD) investigations of the structural, magnetic, and electronic properties of clean and CO-adsorbed ultrathin γ-iron films epitaxially grown on Cu(100) surfaces demonstrate that both the geometrical and the magnetic structures of the films are profoundly modified by the adsorption of CO. The enhanced magnetic moments of the top-layer atoms are strongly quenched by the presence of the adsorbate. Due to the pronounced magnetovolume effect, this leads also to a correlated change in the interlayer relaxations. Strikingly, the adsorbate-induced demagnetization is primarily limited to those surface atoms directly bonded to the adsorbate. This leads to the formation of an in-plane magnetic pattern in a partially adsorbate-covered film. The comparison of the calculated vibrational eigenfrequencies of the CO adsorbate with experiment confirms the picture based on the LSD calculations.

  3. 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.

  4. Presentation and characterization of novel thick-film PZT microactuators

    NASA Astrophysics Data System (ADS)

    Chalvet, Vincent; Habineza, Didace; Rakotondrabe, Micky; Clévy, Cédric

    2016-04-01

    We propose in this paper the characterization of a new generation of piezoelectric cantilevers called thick-films piezoelectric actuators. Based on the bonding and thinning process of a bulk PZT layer onto a silicon layer, these cantilevers can provide better static and dynamic performances compared to traditional piezocantilevers, additionally to the small dimensions.

  5. Electron-Stimulated Oxidation of Thin Water Films Adsorbed on TiO2(110)

    SciTech Connect

    Lane, Christopher D.; Petrik, Nikolay G.; Orlando, Thomas M.; Kimmel, Greg A.

    2007-11-08

    Electron-stimulated reactions in thin (< 3 monolayer, ML) water films adsorbed on TiO2(110) are investigated. For electron fluences less than ~1×1016 e-/cm2, irradiation with 100 eV electrons results in electron-stimulated desorption (ESD) of atomic and molecular hydrogen, but no measurable O2. The ESD leaves adsorbed hydroxyls which oxidize the TiO2(110) surface and change the post-irradiation TPD spectra of the remaining water in characteristic ways. The species remaining on the TiO2(110) after irradiation of adsorbed water films are apparently similar to those produced without irradiation by co-dosing water and O2. Annealing above ~600 K reduces the oxidized surfaces, and water TPD spectra characteristic of ion sputtered and annealed TiO2(110) are recovered. The rate of electron-stimulated “oxidation” of the water films is proportional to the coverage of water in the first layer for coverages less than 1 ML. However, higher coverages suppress this reaction. When thin water films are irradiated, the rate of electron-stimulated oxidation is independent of the initial oxygen vacancy concentration, as is the final oxidized state achieved at high electron fluences. To explain the results, we propose that electron excitation of water molecules adsorbed on Ti4+ sites leads to desorption of hydrogen atoms and leaves an OH adsorbed at the site. If hydroxyls are present in the bridging oxygen rows, these react with the OH’s on the Ti4+ sites to reform water and heal the oxygen vacancy associated with the bridging OH. Once the bridge bonded hydroxyls have been eliminated, further irradiation increases the concentration of OH’s in the Ti4+ rows leading to the creation of species which block sites in the Ti4+ rows, perhaps H2O2 and/or HO2.

  6. Determination of thin hydrodynamic lubricating film thickness using dichromatic interferometry.

    PubMed

    Guo, L; Wong, P L; Guo, F; Liu, H C

    2014-09-10

    This paper introduces the application of dichromatic interferometry for the study of hydrodynamic lubrication. In conventional methods, two beams with different colors are projected consecutively on a static object. By contrast, the current method deals with hydrodynamic lubricated contacts under running conditions and two lasers with different colors are projected simultaneously to form interference images. Dichromatic interferometry incorporates the advantages of monochromatic and chromatic interferometry, which are widely used in lubrication research. This new approach was evaluated statically and dynamically by measuring the inclination of static wedge films and the thickness of the hydrodynamic lubricating film under running conditions, respectively. Results show that dichromatic interferometry can facilitate real-time determination of lubricating film thickness and is well suited for the study of transient or dynamic lubricating problems. PMID:25321689

  7. Enhanced electrocaloric effect in composition gradient bilayer thick films

    NASA Astrophysics Data System (ADS)

    Hou, Ying; Yang, Lu; Qian, Xiaoshi; Zhang, Tian; Zhang, Q. M.

    2016-03-01

    We report the enhanced electrocaloric (EC) response over a broad temperature range in composition gradient Ba(ZrTi)O3 based bilayer thick films. A large EC temperature change of -4.9 K under an electric field of 10 MV/m around room temperature, large electrocaloric coefficient ΔT/ΔE = 0.49 × 10-6 K m V-1 were observed in the BaZr0.17Ti0.83O3/BaZr0.20Ti0.80O3 bilayer thick films, which are improved compared with BaZr0.20Ti0.80O3 and BaZr0.17Ti0.83O3 homogeneous bilayer films. The result reveals the potential of the composition gradient bilayer structure in improving the electrocaloric effect, which may provide an effective route to achieve large EC temperature change under a low electric field.

  8. Ultimate photovoltage in perovskite oxide heterostructures with critical film thickness

    SciTech Connect

    Wang Cong; Jin Kuijuan; Zhao Ruiqiang; Lu Huibin; Guo Haizhong; Ge Chen; He Meng; Wang Can; Yang Guozhen

    2011-05-02

    One order larger photovoltage is obtained with critical thicknesses of La{sub 0.9}Sr{sub 0.1}MnO{sub 3} films in both kinds of heterostructures of La{sub 0.9}Sr{sub 0.1}MnO{sub 3}/SrTiO{sub 3} (0.8 wt % Nb-doped) and La{sub 0.9}Sr{sub 0.1}MnO{sub 3}/Si fabricated at various oxygen pressures. Our self-consistent calculation reveals that the critical thickness of the La{sub 0.9}Sr{sub 0.1}MnO{sub 3} film with the ultimate value of photovoltage is just the thickness of the depletion layer of La{sub 0.9}Sr{sub 0.1}MnO{sub 3} in both heterojunctions, respectively.

  9. Electrical Conductivity of Thick Films Made from Silver Methylcarbamate Paste

    NASA Astrophysics Data System (ADS)

    Liu, Jianguo; Jiang, Min; Zeng, Xiaoyan

    2013-10-01

    We have explored the electrical conductivity of thick films made from silver methylcarbamate paste using metallic silver as the electrically conductive phase. The paste was composed of 30 wt.% to 90 wt.% organic vehicle and 10 wt.% to 70 wt.% functional phase precursor (silver methylcarbamate). After the paste was sintered, films with thickness of 4.50 μm to 12.70 μm were obtained, in which the elemental percentage of silver varied from about 5 wt.% to above 99 wt.%. Experiments showed that both the electrical conductivity and the elemental percentage were mainly affected by the initial silver content in the paste and the parameters of the sintering process. For given sintering conditions, higher initial silver content led to higher elemental percentage of silver, improving the electrical conductivity of the thick film. The conditions of the sintering process had a significant influence on the evaporation and decomposition rates of the paste components, the elemental percentage of silver, and the microstructure of the thick film. Higher temperatures, longer times, lower heating rates, and more oxygen-rich sintering atmospheres were found to accelerate the evaporation and decomposition and increase the elemental percentage of silver, both of which served to enhance the electrical conductivity. For initial silver contents less than about 10 wt.%, the lowest electrical resistivity of the thick film only reached the order of 10-4 Ω cm, irrespective of the sintering conditions. For contents between 10 wt.% and 25 wt.%, it was possible to attain lowest resistivity values on the order of 10-5 Ω cm. Above 25 wt.%, the lowest resistivity could reach 10-6 Ω cm, comparable to that of bulk silver.

  10. Anomalous conformational transitions in cytochrome C adsorbing to Langmuir-Blodgett films

    NASA Astrophysics Data System (ADS)

    Sankaranarayanan, Kamatchi; Nair, B. U.; Dhathathreyan, A.

    2013-05-01

    Helix to beta conformational transitions in proteins has attracted much attention due to their relevance to fibril formation which is implicated in many neurological diseases. This study reports on unusual conformational transition of cytochrome C adsorbing to hydrophilic surface containing pure cationic lipid and mixed Langmuir-Blodgett films (LB films) of cationic and neutral lipids. Evidence for conformational changes of the protein from its native helical state to beta sheet comes from Circular dichroic spectroscopy (CD spectroscopy). Analysis of these samples using High resolution TEM (HRTEM) shows a typical fibrillar pattern with each strand spacing of about 0.41 nm across which can be attributed to the repeat distance of interdigitated neighboring hydrogen-bonded ribbons in a beta sheet. Changes in contact angles of protein adsorbing to the LB films together with the increased mass uptake of water using quartz crystal microbalance (QCM) confirm the role of positive charges in the conformational transition. Dehydration of the protein resulting from the excess water entrainment in the polar planes of the cationic lipid in hydrophilic surface seems to trigger the refolding of the protein to beta sheet while it retains its native conformation in hydrophobic films. The results suggest that drastic conformational changes in CytC adsorbing to cationic lipids may be of significance in its role as a peripheral membrane protein.

  11. Effect of film thickness on morphological evolution in dewetting and crystallization of polystyrene/poly(ε-caprolactone) blend films.

    PubMed

    Ma, Meng; He, Zhoukun; Yang, Jinghui; Chen, Feng; Wang, Ke; Zhang, Qin; Deng, Hua; Fu, Qiang

    2011-11-01

    In this Article, the morphological evolution in the blend thin film of polystyrene (PS)/poly(ε-caprolactone) (PCL) was investigated via mainly AFM. It was found that an enriched two-layer structure with PS at the upper layer and PCL at the bottom layer was formed during spinning coating. By changing the solution concentration, different kinds of crystal morphologies, such as finger-like, dendritic, and spherulitic-like, could be obtained at the bottom PCL layer. These different initial states led to the morphological evolution processes to be quite different from each other, so the phase separation, dewetting, and crystalline morphology of PS/PCL blend films as a function of time were studied. It was interesting to find that the morphological evolution of PS at the upper layer was largely dependent on the film thickness. For the ultrathin (15 nm) blend film, a liquid-solid/liquid-liquid dewetting-wetting process was observed, forming ribbons that rupture into discrete circular PS islands on voronoi finger-like PCL crystal. For the thick (30 nm) blend film, the liquid-liquid dewetting of the upper PS layer from the underlying adsorbed PCL layer was found, forming interconnected rim structures that rupture into discrete circular PS islands embedded in the single lamellar PCL dendritic crystal due to Rayleigh instability. For the thicker (60 nm) blend film, a two-step liquid-liquid dewetting process with regular holes decorated with dendritic PCL crystal at early annealing stage and small holes decorated with spherulite-like PCL crystal among the early dewetting holes at later annealing stage was observed. The mechanism of this unusual morphological evolution process was discussed on the basis of the entropy effect and annealing-induced phase separation. PMID:21936570

  12. Visualization of film wavelike characteristics and measurement of film thickness in spray cooling

    NASA Astrophysics Data System (ADS)

    Hou, Yan; Tao, Yujia; Huai, Xiulan

    2013-04-01

    An experimental investigation was performed to study the heat transfer in an eight-nozzle spray cooling system with de-ionized water as the working fluid. Visualization of the liquid-solid contact area and the flow near the heated surface was made using a microscopic lens system in conjunction with an advanced high-speed camera. The film thickness and film wavelike characteristics under liquid volume flow rates ranged from 2.78×10-6 m3/s to 1.39×10-5 m3/s and surface temperatures between 22°C and 78.2°C were examined respectively. The development process of the liquid film on the heated surface was observed. The local mean film thickness, the film wavelike characteristics and the behavior of the bubbles appeared in the liquid film were captured using an image processing technique. It is discovered that there exists a climax of local mean film thickness during the starting process of spray cooling. When the liquid film reaches the dynamic stable state, the dimensionless mean film thickness decreases with the increase of the liquid volume flow rate, and increases with the increase of surface temperature generally. Besides, the volume flow rate has a more significant impact on the wavelength and amplitude of the liquid film compared to the surface temperature.

  13. Film thickness measurements on five fluid formulations by the mercury squeeze film capacitance technique

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Johnson, R. L.; Hyslop, I.; Day, R.

    1976-01-01

    The thinning characteristics of five fluids were studied by measuring film thickness as a function of time. The mercury squeeze film capacitance technique was used. All tests were performed at room temperature. The synthetic hydrocarbon plus a nematic liquid crystal, N-(p-methoxybenzylidene)-p-butylaniline, thinned according to a Newtonian model and retained its bulk viscosity. The synthetic hydrocarbon plus a phosphonate antiwear additive and the synthetic hydrocarbon plus n-hexadecanol produced residual thick films. The synthetic hydrocarbon base fluids and the synthetic hydrocarbon plus a paraffinic resin displayed viscosity increases during thinning, but no residual films were formed.

  14. Effect of film thickness and particle size on cracking stresses in drying latex films.

    PubMed

    Yow, Huai Nyin; Goikoetxea, Monika; Goehring, Lucas; Routh, Alexander F

    2010-12-15

    The stress at which latex films crack during drying was investigated using beam bending. Two systems were investigated: (i) poly(methyl methacrylate/butyl acrylate) particles cast as thin films to examine the effect of film thickness on cracking film stress and (ii) polystyrene particles dried as drops to investigate the effect of particle size. Results indicated an inverse relationship between film thickness and film stress, whilst film stress was shown to be independent of the original particle size. These outcomes were in good agreement with Tirumkudulu and Russel's theoretical analysis [M.S. Tirumkudulu and W.B. Russel, Langmuir 21 (2005) 4938], albeit the measured stress values were almost twice the theoretical estimation. PMID:20851402

  15. Thickness dependence of superconducting properties in magnesium diboride thin films

    NASA Astrophysics Data System (ADS)

    Beringer, Douglas; Clavero, Cesar; Tan, Teng; Xi, Xiaoxing; Lukaszew, Rosa

    2013-03-01

    Thin film MgB2 is a promising material currently researched for improvements in superconducting radio frequency (SRF) technology and applications. At present, bulk niobium SRF accelerating cavities suffer from a fundamental upper limit in maximally sustained accelerating gradients; however, a scheme involving multi-layered superstructures consisting of superconducting-insulating-superconducting (SIS) layers has been proposed to overcome this fundamental material limit of 50 MV/m. The SIS multi-layer paradigm is reliant upon implementing a thin shielding material with a suitably high Hc1 which may prevent early field penetration in a bulk material layer and consequently delay the high field breakdown. It has been predicted that for thin superconducting films -- thickness less than the London penetration depth (~ 140 nm in the case of MgB2) -- the lower critical field Hc1 will be enhanced with decreasing thickness. Thus, MgB2, with a high bulk Hc1 value is a prime candidate for such SIS structures. Here we present our study on the structure, surface morphology and superconducting properties on a series of MgB2 thin films and correlate the effects of film thickness and surface morphology on Hc1. This work was supported in part by the U.S. Department of Energy (DE-SC0004410 and DE-AC05-06OR23177) and Defense Threat Reduction Agency (HDTRA1-10-1-0072).

  16. Effect of film thickness and texture morphology on the physical properties of lead sulfide thin films

    NASA Astrophysics Data System (ADS)

    Azadi Motlagh, Z.; Azim Araghi, M. E.

    2016-02-01

    Lead sulfide (PbS) thin films were prepared onto ultra-clean quartz substrate by the electron beam gun (EBG) evaporation method. The thicknesses of the thin films were 50, 100, 150 and 200 nm. They were annealed at 423 K for 2 h. Field emission scanning electron microscopy (FESEM) images of the thin films showed their texture morphology at the surface of the quartz substrate. X-ray diffraction (XRD) patterns of the thin films showed that they have a cubic phase and rock-salt structure after annealing. The average crystallite size for the thin films was in the range of 32-100 nm. Optical measurements confirmed that crystalline thin films have a direct band gap that increases by decreasing the film thickness. This blue shift of the band gap of thin films compared to the bulk structure can be attributed to the quantum confinement effects in the nanoparticles. A decrease in conductivity by increasing the temperature confirmed the positive temperature coefficient of resistance in the thin films that showed the dominant conduction mechanism is via a band-like transition. The density of localized states at the Fermi level increases by increasing the film thickness. Current-voltage behavior of the thin films showed an increase in both dark current and photocurrent by increasing the crystallite size which is discussed, based on the presence of trap states and barriers in nanostructures.

  17. Structural investigations of adsorbed films of Methyl Halides on Boron Nitride

    NASA Astrophysics Data System (ADS)

    Sprung, Michael; Freitag, Andrea; Hanson, Jonathan; Larese, John

    2000-03-01

    The Methyl Halides are a group of molecules whose properties of thin adsorbed films on Graphite have been well characterized. Boron Nitride forms a hexagonal structure with a slightly larger (about 2% ) unit cell than Graphite. The study of thin films of Methyl Halides (CH_3R, R=Cl, Br and I) on Boron Nitride is motivated by the hope to gain a better understanding of adsorbate-substrate interaction. High resolution adsorption isotherms and x-ray powder diffraction have been used to investigate the monolayer structures of CH_3R adsorbed on Boron Nitride. The experiments were carried out at the Beamline X7B of the NSLS. The gases were dosed onto the sample with an automated gas handling system, and a Mar345 image plate detector was used to collect the data. The measurements were performed in a temperature range between 50 and 175 K. All three adsorbates form a solid monolayer structure on Boron Nitride at low temperature. The structure of Methyl Chloride and Methyl Bromide is very similar to the high-density structure of CH_3Cl on Graphite. This is surprising for CH_3Br because it forms a different structure on Graphite. Methyl Iodide forms similar structures on both substrates.

  18. Aggregate formation of eosin-Y adsorbed on nanocrystalline TiO2 films

    NASA Astrophysics Data System (ADS)

    Yaguchi, Kaori; Furube, Akihiro; Katoh, Ryuzi

    2012-11-01

    We have studied the adsorption of eosin-Y on nanocrystalline TiO2 films with two different solvents namely acetonitrile (ACN) and ethanol (EtOH). A Langmuir-type adsorption isotherm was observed with ACN. In contrast, a Freundlich-type adsorption isotherm was observed with EtOH, suggesting that EtOH molecules co-adsorbed on TiO2 surface. Absorption spectra of the dye adsorbed films clearly show aggregate formation at high concentrations of dye in the solutions. From the analysis of the spectra, we conclude that head-to-tail type aggregates are observed with ACN, whereas various types of aggregates, including H-type and head-to-tail type aggregates, are observed with EtOH.

  19. Ultrasonic array of thick film transducers for biological tissue characterization.

    PubMed

    Gwirc, Sergio N; Negreira, Carlos A; Marino, Nestor R

    2010-01-01

    The initial motivation for this work was to accomplish an easy way to manufacture different geometries of ultrasonic transducers and arrays using a PZT powder, combined with a standard process to have repetitive series of them. The piezoelectric thick film was obtained using a PZT paste and applying it by screen printing on an alumina substrate. Then, the film was drying and sintered with a temperature-time profile determined by the paste characteristics. Each transducer is composed by three layers, one by PZT and two acting as electrodes. The active element of the paste is a PZT powder which is dispersed in a commercial vehicle to obtain rheological properties suitable for use the screen printing process. The connection between PZT particles is improved by adding a lead borosilicate frit glass that also helps to attach the film to the substrate due to the relatively low temperature of sintered that has been used in this process. The PZT film has low density that is generated by internal porosity, so its acoustic impedance is lower than for a bulk ceramic transducer and so is well adapted to testing human tissues. At the same time the thick film technology is well suited to make medium size transducers and also arrays performed with tiny ultrasonic transducers. PMID:21097177

  20. Chemical vapor deposition reactor. [providing uniform film thickness

    NASA Technical Reports Server (NTRS)

    Chern, S. S.; Maserjian, J. (Inventor)

    1977-01-01

    An improved chemical vapor deposition reactor is characterized by a vapor deposition chamber configured to substantially eliminate non-uniformities in films deposited on substrates by control of gas flow and removing gas phase reaction materials from the chamber. Uniformity in the thickness of films is produced by having reactive gases injected through multiple jets which are placed at uniformally distributed locations. Gas phase reaction materials are removed through an exhaust chimney which is positioned above the centrally located, heated pad or platform on which substrates are placed. A baffle is situated above the heated platform below the mouth of the chimney to prevent downdraft dispersion and scattering of gas phase reactant materials.

  1. Thickness Dependence Magnetization in Laser Ablated Ni-Cu-Zn Ferrite Nanostructured Thin Films.

    PubMed

    Raghavender, A T; Hong, Nguyen Hoa; Lee, Kyu Joon; Jung, Myung-Hwa

    2016-01-01

    Ni₀.₅Cu₀.₃Zn₀.₂Fe₂O₄ thin films with thickness ranging from 25 nm to 500 nm were grown on Si substrate using pulsed laser deposition technique and their structural and magnetic properties were investigated. From the atomic force microscopy (AFM) analysis, it is observed that the film roughness (Ra) depends strongly on the thickness of the fabricated film. The magnetizations of the thin films were found to decrease when the film thickness increases. The thinner films showed a larger magnetization than the thick films. All the films showed a blocking temperature indicating their superparamagnetic behavior. PMID:27398528

  2. ASM stepper alignment through thick epitaxial silicon films

    NASA Astrophysics Data System (ADS)

    Black, Iain

    1999-04-01

    High voltage bipolar and BiCMOS processes often use thick epitaxially grown layers of silicon. These films 12-24 micrometers thick offer a considerable challenge to the alignment of subsequent process layers due to the 'wash out' and image distortion, caused to any underlying pattern, which render automatic alignment mark recognition difficult it not impossible. Historically using projection aligner technology these immediately post Epi layers have been manually aligned with future automatic alignment target defined at the first opportunity post Epi. This is not possible using ASM steppers, as these depend upon marks etched into the silicon, before first processing, to create marks, to which all subsequent layers are registered. To allow the stepper to run wafers with these Epi films a new approach was required.

  3. 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.

  4. Texture characterization of high T sub c thick films

    SciTech Connect

    Biondo, A.C.; Kallend, J.S.; Poeppel, R.B.; Lanagan, M.T. ); Schofield, T.C. )

    1990-06-01

    The anisotropic properties which exist in all high-{Tc} compounds make it necessary to characterize the preferred orientation (or texture) of crystals which results from various processing methods. Once a suitable preferred orientation is achieved, a significant increase in performance is anticipated. In this study, thick films ({approximately}80 {mu}m) of Bi-Sr-Ca-Cu-O (BSCCO) on silver substrates were characterized by pole figure techniques to obtain an Orientation Distribution Function (ODF). 6 refs., 5 figs.

  5. Development of Thick-Film Thermoelectric Microcoolers Using Electrochemical Deposition

    NASA Technical Reports Server (NTRS)

    Fleurial, J.-P.; Borshchevsky, A.; Ryan, M. A.; Phillips, W. M.; Snyder, J. G.; Caillat, T.; Kolawa, E. A.; Herman, J. A.; Mueller, P.; Nicolet, M.

    2000-01-01

    Advanced thermoelectric microdevices integrated into thermal management packages and low power, electrical source systems are of interest for a variety of space and terrestrial applications. By shrinking the size of the thermoelements, or legs, of these devices, it becomes possible to handle much higher heat fluxes, as well as operate at much lower currents and higher voltages that are more compatible with electronic components. The miniaturization of state-of-the-art thermoelectric module technology based on Bi2Te3 alloys is limited due to mechanical and manufacturing constraints for both leg dimensions (100-200 gm thick minimum) and the number of legs (100-200 legs maximum). We are investigating the development of novel microdevices combining high thermal conductivity substrate materials such as diamond, thin film metallization and patterning technology, and electrochemical deposition of thick thermoelectric films. It is anticipated that thermoelectric microcoolers with thousands of thermocouples and capable of pumping more than 200 W/sq cm over a 30 to 60 K temperature difference can be fabricated. In this paper, we report on our progress in developing an electrochemical deposition process for obtaining 10-50 microns thick films of Bi2Te3 and its solid solutions. Results presented here indicate that good quality n-type Bi2Te3, n-type Bi2Te(2.95)Se(0.05) and p-type Bi(0.5)Sb(1.5)Te3 thick films can be deposited by this technique. Some details about the fabrication of the miniature thermoelements are also described.

  6. Ice-Accretion Scaling Using Water-Film Thickness Parameters

    NASA Technical Reports Server (NTRS)

    Anderson, David N.; Feo, Alejandro

    2003-01-01

    Studies were performed at INTA in Spain to determine water-film thickness on a stagnation-point probe inserted in a simulated cloud. The measurements were correlated with non-dimensional parameters describing the flow and the cloud conditions. Icing scaling tests in the NASA Glenn Icing Research Tunnel were then conducted using the Ruff scaling method with the scale velocity found by matching scale and reference values of either the INTA non-dimensional water-film thickness or a Weber number based on that film thickness. For comparison, tests were also performed using the constant drop-size Weber number and the average-velocity methods. The reference and scale models were both aluminum, 61-cm-span, NACA 0012 airfoil sections at 0 deg. AOA. The reference had a 53-cm-chord and the scale, 27 cm (1/2 size). Both models were mounted vertically in the center of the IRT test section. Tests covered a freezing fraction range of 0.28 to 1.0. Rime ice (n = 1.0) tests showed the consistency of the IRT calibration over a range of velocities. At a freezing fraction of 0.76, there was no significant difference in the scale ice shapes produced by the different methods. For freezing fractions of 0.40, 0.52 and 0.61, somewhat better agreement with the reference horn angles was typically achieved with the average-velocity and constant-film thickness methods than when either of the two Weber numbers was matched to the reference value. At a freezing fraction of 0.28, the four methods were judged equal in providing simulations of the reference shape.

  7. Elastohydrodynamic film thickness measurements of artificially produced nonsmooth surfaces

    NASA Technical Reports Server (NTRS)

    Cusano, C.; Wedeven, L. D.

    1979-01-01

    Optical interferometry is used to measure the elastohydrodynamic (EHD) film thickness associated with artificially produced nonsmooth surfaces. The nonsmooth surfaces are produced by modifying the surfaces of highly-polished balls with irregularities in the form of multiple grooves and dents. By closely spacing these irregularities it is possible not only to produce depressions on the surface of the balls but also to generate pseudo asperities. The average roughness wavelength of this artificially-produced, nonsmooth, surface approximates the average fundamental roughness wavelength found on surfaces of some mechanical elements operating under concentrated contact. By comparing the measured film thickness profiles to the stylus traces of the irregularities, it was possible to observe the local deformations associated with micro-EHD pressure generation. In both pure rolling and pure sliding conditions the artificially-produced asperities are deformed and complete separation exists between them and the mating surface. Such findings demonstrate the importance of local surface topography and resulting micro-EHD effects on the film thickness between rough surfaces in concentrated contact. Sliding data are presented which demonstrate a severe constriction, caused by the irregularities, at the exit of the Hertzian region.

  8. Surfactant micelles containing solubilized oil decrease foam film thickness stability.

    PubMed

    Lee, Jongju; Nikolov, Alex; Wasan, Darsh

    2014-02-01

    Many practical applications involving three-phase foams (aqueous foams containing oil) commonly employ surfactants at several times their critical micelle concentration (CMC); in these applications, the oil can exist in two forms: (1) oil drops or macroemulsions and (2) oil solubilized within the micelles. We have recently observed that in the case of aqueous foams stabilized with sodium dodecyl sulfate (SDS) and n-dodecane as an oil, the oil drops did not alter the foam stability but the solubilized oil (swollen micelles) greatly influenced the foam's stability. In order to explain the effect of oil solubilized in the surfactant micelles on foam stability, we studied the stability of a single foam film containing swollen micelles of SDS using reflected light microinterferometry. The film thinning occurs in stepwise manner (stratification). In addition, we obtained data for the film-meniscus contact angle versus film thickness (corresponding to the different number of micellar layers) and used it to calculate the film structural energy isotherm. The results of this study showed that the structural energy stabilization barrier decreased in the presence of swollen micelles in the film, thereby decreasing the foam stability. These results provide a better understanding of the role of oil solubilized by the micelles in affecting foam stability. PMID:24267325

  9. Tape casting and partial melting of Bi-2212 thick films

    NASA Technical Reports Server (NTRS)

    Buhl, D.; Lang, TH.; Heeb, B.; Gauckler, L. J.

    1995-01-01

    To produce Bi-2212 thick films with high critical current densities tape casting and partial melting is a promising fabrication method. Bi-2212 powder and organic additives were mixed into a slurry and tape casted onto glass by the doctor blade tape casting process. The films were cut from the green tape and partially molten on Ag foils during heat treatment. We obtained almost single-phase and well-textured films over the whole thickness of 20 microns. The orientation of the (a,b)-plane of the grains was parallel to the substrate with a misalignment of less than 6 deg. At 77 K/0T a critical current density of 15, 000 A/sq cm was reached in films of the dimension 1 cm x 2 cm x 20 microns (1 micron V/cm criterion, resistively measured). At 4 K/0T the highest value was 350,000 A/sq cm (1 nV/cm criterion, magnetically measured).

  10. Tape casting and partial melting of Bi-2212 thick films

    SciTech Connect

    Buhl, D.; Lang, T.; Heeb, B.

    1994-12-31

    To produce Bi-2212 thick films with high critical current densities tape casting and partial melting is a promising fabrication method. Bi-2212 powder and organic additives were mixed into a slurry and tape casted onto glass by the doctor blade tape casting process. The films were cut from the green tape and partially molten on Ag foils during heat treatment. We obtained almost single-phase and well-textured films over the whole thickness of 20 {mu}m. The orientation of the (a,b)-plane of the grains were parallel to the substrate with a misalignment of less than 6{degrees}. At 77K/OT a critical current density of 15`000 A/cm{sup 2} was reached in films of the dimension 1cm x 2cm x 20{mu}m (1{mu}V/cm criterion, resistively measured). At 4K/OT the highest value was 350`000 A/cm{sup 2} (1nV/cm criterion, magnetically measured).

  11. Effect of Substrates on Film Hardness Measurements of Nanometer Thick Amorphous Carbon Films

    NASA Astrophysics Data System (ADS)

    Akasaka, Hiroki; Ito, Hiroki; Nakano, Masayuki; Ohshio, Shigeo; Saitoh, Hidetoshi

    Amorphous carbon film (a-C:H) applications, such as hard disks, require films with nanometer thicknesses. In an indentation test, the obtained hardness values of these films are affected by substrates. On the indentation tests, we studied the effect of substrate hardness on films less than 200 nm in thickness. a-C:H and Si doped a-C:H (a-C:Si:H) films were deposited by electron cyclotron resonance plasma chemical vapor deposition onto aluminum (Al) and silicon (Si) substrates. The film thicknesses were approximately 140 nm. The hardnesses of the a-C:H film and substrates were obtained using a high-resolution indentation tester (pico-dentor) with a Vickers tip whose depth resolution was 0.04 nm. Maximum indentation loads were varied from 0.01 to 0.5 mN. The Martens hardnesses of films on the Al and Si substrates were 600 and 7000 N/mm2, respectively. On the a-C:Si:H film deposited on the Al substrate, the hardnesses increased from 1600 to 3900 N/mm2 with decreasing indentation load. The hardnesses of the films deposited on the Si substrate decreased from 5300 to 3500 N/mm2 when the maximum indentation loads were reduced. The effect of the substrates increased with the maximum load increasing. From these findings, the actual hardness value was determined to be 3600 N/mm2. These results indicate that the high-resolution indentation test achieved hardness estimations for nanometer-thick films with certain hardnesses.

  12. Parched elasto hydrodynamic lubrication film thickness measurement in an instrument ball bearing

    NASA Technical Reports Server (NTRS)

    Kingsbury, E.; Schritz, B.; Prahl, J.

    1988-01-01

    Parched Elasto Hydrodynamic Lubricant (PEHL) film thickness in a large instrument ball bearing is measured by electrical capacitance across its ball set. Correlation is shown between changes in film thickness and changes in Basic Speed Ratio (BSR) measured at the same time. BSR is confirmed as a sensitive, non-intrusive measure of transients in film thickness in a real bearing.

  13. AC microcalorimetry of adsorbates on evaporated metal films: Orientational ordering of H{sub 2} multilayers

    SciTech Connect

    Phelps, R.B.

    1991-11-01

    We have improved and extended a novel ac calorimetric technique for measuring the heat capacity of adsorbates on evaporated metal films. Metallic substrates are of particular interest in current studies of the thermodynamics of adsorbed molecules. The method described in the present work is only calorimetric technique which allows measurements of molecules on simple metallic surfaces. Among other improvements, we have achieved significant progress in the preparation and characterization of the evaporated metal film. We have applied this novel technique to a study of hydrogen multilayers on gold and sapphire substrates. We have shown that samples of normal-hydrogen with a nominal coverage n of approximately 25 monolayers (ML) undergo a bulk-like orientational ordering transition. The transition is suppressed as the coverage is decreased, and no sign of the transition remains above 1.6 K for n {approx} 1 ML. For n {approx_lt} 8 ML, the peak in the heat capacity exhibits signs of finite-size effects. At higher coverages, finite-size effects are not observed, and the shape of the peak depends strongly on the substrate. We conclude that the peak is inhomogeneously broadened for n {approx_lt} 8 ML. This work represents the first measurements of the heat capacity due to orientational ordering in adsorbed hydrogen. The results of an earlier experiment involving vibrational spectroscopy of adsorbed molecules are included in the Appendix. In this work, we have used infrared emission spectroscopy to study the spectral region in the vicinity of the C=O stretch vibration of bridge-bonded CO on Pt(111).

  14. AC microcalorimetry of adsorbates on evaporated metal films: Orientational ordering of H sub 2 multilayers

    SciTech Connect

    Phelps, R.B.

    1991-11-01

    We have improved and extended a novel ac calorimetric technique for measuring the heat capacity of adsorbates on evaporated metal films. Metallic substrates are of particular interest in current studies of the thermodynamics of adsorbed molecules. The method described in the present work is only calorimetric technique which allows measurements of molecules on simple metallic surfaces. Among other improvements, we have achieved significant progress in the preparation and characterization of the evaporated metal film. We have applied this novel technique to a study of hydrogen multilayers on gold and sapphire substrates. We have shown that samples of normal-hydrogen with a nominal coverage n of approximately 25 monolayers (ML) undergo a bulk-like orientational ordering transition. The transition is suppressed as the coverage is decreased, and no sign of the transition remains above 1.6 K for n {approx} 1 ML. For n {approx lt} 8 ML, the peak in the heat capacity exhibits signs of finite-size effects. At higher coverages, finite-size effects are not observed, and the shape of the peak depends strongly on the substrate. We conclude that the peak is inhomogeneously broadened for n {approx lt} 8 ML. This work represents the first measurements of the heat capacity due to orientational ordering in adsorbed hydrogen. The results of an earlier experiment involving vibrational spectroscopy of adsorbed molecules are included in the Appendix. In this work, we have used infrared emission spectroscopy to study the spectral region in the vicinity of the C=O stretch vibration of bridge-bonded CO on Pt(111).

  15. Auto-calibration of ultrasonic lubricant-film thickness measurements

    NASA Astrophysics Data System (ADS)

    Reddyhoff, T.; Dwyer-Joyce, R. S.; Zhang, J.; Drinkwater, B. W.

    2008-04-01

    The measurement of oil film thickness in a lubricated component is essential information for performance monitoring and design. It is well established that such measurements can be made ultrasonically if the lubricant film is modelled as a collection of small springs. The ultrasonic method requires that component faces are separated and a reference reflection recorded in order to obtain a reflection coefficient value from which film thickness is calculated. The novel and practically useful approach put forward in this paper and validated experimentally allows reflection coefficient measurement without the requirement for a reference. This involves simultaneously measuring the amplitude and phase of an ultrasonic pulse reflected from a layer. Provided that the acoustic properties of the substrate are known, the theoretical relationship between the two can be fitted to the data in order to yield reflection coefficient amplitude and phase for an infinitely thick layer. This is equivalent to measuring a reference signal directly, but importantly does not require the materials to be separated. The further valuable aspect of this approach, which is demonstrated experimentally, is its ability to be used as a self-calibrating routine, inherently compensating for temperature effects. This is due to the relationship between the amplitude and phase being unaffected by changes in temperature which cause unwanted changes to the incident pulse. Finally, error analysis is performed showing how the accuracy of the results can be optimized. A finding of particular significance is the strong dependence of the accuracy of the technique on the amplitude of reflection coefficient input data used. This places some limitations on the applicability of the technique.

  16. Method for making thick and/or thin film

    DOEpatents

    Pham, Ai Quoc; Glass, Robert S.

    2004-11-02

    A method to make thick or thin films a very low cost. The method is generally similar to the conventional tape casting techniques while being more flexible and versatile. The invention involves preparing a slip (solution) of desired material and including solvents such as ethanol and an appropriate dispersant to prevent agglomeration. The slip is then sprayed on a substrate to be coated using an atomizer which spreads the slip in a fine mist. Upon hitting the substrate, the solvent evaporates, leaving a green tape containing the powder and other additives, whereafter the tape may be punctured, cut, and heated for the desired application. The tape thickness can vary from about 1 .mu.m upward.

  17. Residual stress measurement and microstructural characterization of thick beryllium films

    SciTech Connect

    Detor, A; Wang, M; Hodge, A M; Chason, E; Walton, C; Hamza, A V; Xu, H; Nikroo, A

    2008-02-11

    Beryllium films are synthesized by a magnetron sputtering technique incorporating in-situ residual stress measurement. Monitoring the stress evolution in real time provides quantitative through-thickness information on the effects of various processing parameters, including sputtering gas pressure and substrate biasing. Specimens produced over a wide range of stress states are characterized via transmission and scanning electron microscopy, and atomic force microscopy, in order to correlate the stress data with microstructure. A columnar grain structure is observed for all specimens, and surface morphology is found to be strongly dependent on processing conditions. Analytical models of stress generation are reviewed and discussed in terms of the observed microstructure.

  18. Observation of Cavity QED in thick dielectric films

    NASA Astrophysics Data System (ADS)

    Sarabi, Bahman; Ramanayaka, A. N.; Gladchenko, S.; Stoutimore, M. J. A.; Khalil, M. S.; Osborn, K. D.

    2013-03-01

    Cavity QED in amorphous dielectrics is investigated by measuring five linear superconducting resonators with thick dielectric films and capacitor volumes ranging from 80 μm3 to 5000 μm3. In the smallest volume dielectrics we observe additional resonances which may be explained by CQED, despite the dielectric volume which is many orders of magnitude larger than Josephson junction barrier volumes. In addition to the volume dependence of the CQED resonances, we will report on the stability of the resonances in time and the phase noise. This research allows new fundamental studies on TLS phenomena in meso-volume amorphous dielectrics.

  19. Thick film magnetic nanoparticulate composites and method of manufacture thereof

    NASA Technical Reports Server (NTRS)

    Ma, Xinqing (Inventor); Zhang, Yide (Inventor); Ge, Shihui (Inventor); Zhang, Zongtao (Inventor); Yan, Dajing (Inventor); Xiao, Danny T. (Inventor)

    2009-01-01

    Thick film magnetic/insulating nanocomposite materials, with significantly reduced core loss, and their manufacture are described. The insulator coated magnetic nanocomposite comprises one or more magnetic components, and an insulating component. The magnetic component comprises nanometer scale particles (about 1 to about 100 nanometers) coated by a thin-layered insulating phase. While the intergrain interaction between the immediate neighboring magnetic nanoparticles separated by the insulating phase provides the desired soft magnetic properties, the insulating material provides high resistivity, which reduces eddy current loss.

  20. Thick film fabrication of aluminum nitride microcircuits. Final report

    SciTech Connect

    Perdieu, L.H.

    1994-03-01

    A new substrate material, aluminum nitride (AlN), and 11 new thick film inks were analyzed to determine their chemical compatibility, their electrical properties, their mechanical properties, and their overall suitability for use in the manufacturing of high-power microcircuits with efficient thermal properties. Because high-power chips emit a great deal of heat in a small surface area, a new substrate material was needed to dissipate that heat faster than the substrate material currently in use. Overall, the new materials were found to be acceptable for accomplishing this purpose.

  1. Film thickness for different regimes of fluid-film lubrication. [elliptical contacts

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1983-01-01

    Mathematical formulas are presented which express the dimensionless minimum film thickness for the four lubrication regimes found in elliptical contacts: isoviscous-rigid regime; piezoviscous-rigid regime; isoviscous-elastic regime; and piezoviscous-elastic regime. The relative importance of pressure on elastic distortion and lubricant viscosity is the factor that distinguishes these regimes for a given conjunction geometry. In addition, these equations were used to develop maps of the lubrication regimes by plotting film thickness contours on a log-log grid of the dimensionless viscosity and elasticity parameters for three values of the ellipticity parameter. These results present a complete theoretical film thickness parameter solution for elliptical constants in the four lubrication regimes. The results are particularly useful in initial investigations of many practical lubrication problems involving elliptical conjunctions.

  2. Effects of accumulated film layers on the accuracy of quartz film thickness monitors

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.; Miller, W. E.

    1978-01-01

    The effect of accumulation layers on the accuracy of quartz thin-film thickness monitors is evaluated. Use of an expanded plane wave ultrasonic propagation theory correctly accounts for observed experimental data. The magnitude of the maximum errors calculated for simply reversing the order of a series of aluminum gold deposits is on the order of 5%. If one totally neglects intervening layers, multiple film propagation and nonlinearity can produce errors greater than 50%.

  3. Nitrogen dioxide sensing properties of sprayed tungsten oxide thin film sensor: Effect of film thickness.

    PubMed

    Ganbavle, V V; Mohite, S V; Agawane, G L; Kim, J H; Rajpure, K Y

    2015-08-01

    We report a study on effect of film thickness on NO2 sensing properties of sprayed WO3 thin films. WO3 thin films varying in thicknesses are deposited onto the glass substrates by simple spray pyrolysis technique by varying the volume of spray solution.Thin film gas sensors are characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and photoluminescence (PL) techniques to study their physical properties. Film having thickness 745nm has shown highest gas response of 97% with 12 and 412s response and recovery times, respectively towards 100ppm NO2 concentration. Gas response of 20% is observed towards 10ppm NO2 at 200°C operating temperature. Sensitivity of the optimal sensor is 0.83%/ppm when operating at 200°C with 10ppm lower detection limit. The response of the sensor is reproducible and WO3 films are highly selective towards NO2 in presence of mist of various interfering gases viz. H2S, NH3, LPG, CO and SO2. PMID:25898119

  4. Environmentally compatible solder materials for thick film hybrid assemblies

    SciTech Connect

    Hosking, F.M.; Vianco, P.T.; Rejent, J.A.; Hernandez, C.L.

    1997-02-01

    New soldering materials and processes have been developed over the last several years to address a variety of environmental issues. One of the primary efforts by the electronics industry has involved the development of alternative solders to replace the traditional lead-containing alloys. Sandia National Laboratories is developing such alternative solder materials for printed circuit board and hybrid microcircuit (HMC) applications. This paper describes the work associated with low residue, lead-free soldering of thick film HMC`s. The response of the different materials to wetting, aging, and mechanical test conditions was investigated. Hybrid test vehicles were designed and fabricated with a variety of chip capacitors and leadless ceramic chip carriers to conduct thermal, electrical continuity, and mechanical evaluations of prototype joints. Microstructural development along the solder and thick film interface, after isothermal solid state aging over a range of elevated temperatures and times, was quantified using microanalytical techniques. Flux residues on soldered samples were stressed (temperature-humidity aged) to identify potential corrosion problems. Mechanical tests also supported the development of a solder joint lifetime prediction model. Progress of this effort is summarized.

  5. Na+ and Li+ NASICON Superionic Conductors Thick Films

    NASA Astrophysics Data System (ADS)

    Perthuis, H.; Velasco, G.; Colomban, Ph.

    1984-05-01

    For microionic applications, superionic conductors have been elaborated in the form of thick films, using silk-screen printable powders. Na3Zr2Si2PO12, Na3.1Zr1.55Si2.3P0.7O11 and Li0.8Zr1.8Ta0.2(PO4)3 compositions are synthesized by a sol-gel process involving hydrolysis-polycondensation reactions of metal-organic alcoholic solutions. A thermal treatment (600°C-800°C) allows to obtain very fine particles (<1 μm) with the pure NASICON phase. Inks are prepared with these powders, an organic binder, volatile fluidifying agents and mineralizers. The layers, about 50 μm in thickness, are achieved by successive deposits and sinterings (950°C-1050°C) onto alumina substrates. Films conductivity is determined by the complex impedance method. Values measured at 300°C (Na+: σ˜10-2 Ω-1cm-1, EA{=}0.25 eV, Li+: σ˜5 10-4 Ω-1cm-1, EA{=}0.5 eV) reach those obtained with well-densified ceramics. An anisotropic behaviour related to microstructure is pointed out.

  6. Atomic force microscopy of AgBr crystals and adsorbed gelatin films

    SciTech Connect

    Haugstad, G.; Gladfelter, W.L.; Keyes, M.P.; Weberg, E.B.

    1993-06-01

    Atomic force microscopy of the (111) surface of macroscopic AgBr crystals revealed steps ranging in height from two atomic layers up to 10 nm, lying predominantly along the (110) and (112) families of crystal directions. Rods of elemental Ag, formed via photoreduction, were observed along the (110) family of directions. Images of adsorbed gelatin films revealed circular pores with diameters of order 10-100 nm, extending to the AgBr surface. The length of deposition time, the pH and concentration of the gelatin solution, and the presence of steps on the AgBr surface were observed to affect the size, number, and location of pores in the gelatin films. 12 refs., 7 figs.

  7. Ultrasonic measurement of lubricant film thickness in sliding bearings with thin liners

    NASA Astrophysics Data System (ADS)

    Geng, Tao; Meng, Qingfeng; Zhang, Kai; Yuan, Xiaoyang; Jia, Qian

    2015-02-01

    When conducting ultrasonic measurements of the lubricant film thickness in sliding bearings with thin liners, the ultrasonic pulse reflected from the bearing liner-lubricant film interface will superimpose on the pulse reflected from the bearing substrate-liner interface. The thickness information of the lubricant film is contained in the reflected pulse from the liner-lubricant film interface. In this case, the film thickness could not be obtained directly from the superimposed reflected signals. The thin liner indicates that the thickness of the bearing liner is less than half the ultrasonic pulse width. Based on the spectrum analysis method of superimposed signals, a new method is proposed to measure the lubricant film thickness in sliding bearings with thin liners. The frequency-domain amplitude ratio between the echo component containing thickness information and the steady echo component from the bearing substrate-liner interface is extracted from the superimposed signal. The reflection coefficient of the liner-lubricant film interface is obtained by this amplitude ratio to determine the film thickness. The lubricant films of different thicknesses in a thin-liner thrust pad were measured in a high-precision experimental apparatus. The measurement results were compared with the known film thickness set by the experimental apparatus. In the thinner film region, the measurement results agreed well with the set film thickness. In the thicker film region, the mean values of the multiple measurement results represented the film thickness. The experimental results show that the method can be used to measure the lubricant film thickness in sliding bearings with thin liners.

  8. Nanotribological properties of water films adsorbing atop, and absorbing below, graphene layers supported by metal substrates

    NASA Astrophysics Data System (ADS)

    Liu, Zijian; Curtis, C. K.; Stine, R.; Sheehan, P.; Krim, J.

    The tribological properties of graphite, a common lubricant with known sensitivity to the presence of water, have been studied extensively at the macroscopic and microscopic scales. Although far less attention has been devoted to the tribological properties of graphene, it has been established that the tribological response to the presence of water is dissimilar from that of graphite. We report here a quartz crystal microbalance study of the nanotribological properties of water films adsorbed/absorbed on graphene layers prepared by either chemical decomposition on nickel(111) substrates or transfer of freestanding graphene layers to aluminum substrates. Sliding friction levels of the water films were also measured for metal surfaces in the absence of a graphene layer. We observe very high friction levels for water adsorbed atop graphene on Ni(111) and very low levels for water on aluminum. For the case of graphene/aluminum, the data indicate that the water is absorbing between the graphene layer and the aluminum. Dissipation levels moreover indicate the presence of an interstitial water increases sliding friction between the graphene and the aluminum substrate Work supported by NSF and NRL.

  9. Atomic Motion in Low-Coverage Helium Films Adsorbed in FSM Nanochannels

    NASA Astrophysics Data System (ADS)

    Matsushita, Taku; Kuze, Atsushi; Kawai, Ryosuke; Hieda, Mitsunori; Wada, Nobuo

    2013-06-01

    4He and 3He films adsorbed in nanoporous silicates have shown similar heat capacities until the quantum-fluid layer appears at coverages over the first-layer completion n 1. To obtain information on dynamics of adatoms at low coverages below the quantum fluid region, we have done pulsed-NMR experiment at 3.3 MHz for 3He films adsorbed in straight 2.4 nm nanochannels of FSM silicates. The spin-lattice and spin-spin relaxation times T 1 and T 2 observed at 0.54-7 K were well described by the two-dimensional version of the Bloembergen-Purcell-Pound model. At coverages 0.4-1.7 n 1, minima of T 1, indicating the spin correlation time τ c of 4.8×10-8 sec, were observed at temperatures between 6 and 3 K. With decreasing temperature, changes in T 1 and T 2 become small below about 1.5 K, suggesting crossover from thermally-activated motion to quantum tunneling. In contrast to large variations below n 1, both relaxation times above n 1 are almost independent of coverage, which is likely to indicate that τ c is determined by interlayer exchange of adatoms. Below n 1, onsets for localization of adatoms were suggested by a decrease in T 2.

  10. Thickness and temperature dependence of stress relaxation in nanoscale aluminum films

    NASA Astrophysics Data System (ADS)

    Hyun, S.; Brown, W. L.; Vinci, R. P.

    2003-11-01

    We have found that stress relaxation of nanoscale Al thin films is strongly dependent on both film thickness and temperature. Films 33, 107, and 205 nm thick prepared by evaporation onto a silicon nitride membrane substrate were studied using membrane resonance. A single thermal cycle to 300 °C was used to establish a stress, after which the time dependence of the stress was measured for the three film thicknesses at 50, 75, and 100 °C. The relaxation rate is highest for the highest temperature and the thinnest film. A dislocation locking mechanism is suggested as a possible explanation for the observed thickness dependence.

  11. Liquid phase epitaxy of REBCO (RE=Y, Sm) thick films on YBCO thin film deposited on LAO substrate

    NASA Astrophysics Data System (ADS)

    Guo, L. S.; Chen, Y. Y.; Cheng, L.; Li, W.; Xiong, J.; Tao, B. W.; Yao, X.

    2013-03-01

    By employing YBCO/LAO thin films as seeds, we succeeded in growing REBa2Cu3Ox (REBCO, RE=Y, Sm) thick films via the LPE method in air. Remarkably, a completely covered YBCO thick film with the c-axis orientation was achieved. Moreover, SmBCO LPE films were effectively induced by the YBCO/LAO thin films at a processing temperature of 1055 °C, indicating that the YBCO/LAO thin film possesses a superheating property. Compared with the YBCO/MgO thin film, the YBCO/LAO thin film has a potentially higher thermal stability in LPE, due to its better lattice fitness at the film/substrate interface. On the other hand, compared to the thick films induced by NdGaO3 (NGO) substrates, YBCO/LAO thin-film-seeded thick films have the broad average spacing of about 150 μm between adjacent cracks, almost five times wider than the former, which benefits the practical application in electronic devices. In short, the YBCO/LAO thin film becomes a third promising candidate for inducing REBCO LPE thick films, combined with conventionally used YBCO/MgO thin films and single-crystal NGO substrates.

  12. Influence of colorant and film thickness on thermal aging characteristics of oxo-biodegradable plastic bags

    NASA Astrophysics Data System (ADS)

    Leuterio, Giselle Lou D.; Pajarito, Bryan B.; Domingo, Carla Marie C.; Lim, Anna Patricia G.

    2016-05-01

    Functional, lightweight, strong and cheap plastic bags incorporated with pro-oxidants undergo accelerated degradation under exposure to heat and oxygen. This work investigated the effect of colorant and film thickness on thermal aging characteristics of commercial oxo-biodegradable plastic bag films at 70 °C. Degradation is monitored through changes in infrared absorption, weight, and tensile properties of thermally aged films. The presence of carbonyl band in infrared spectrum after 672 h of thermal aging supports the degradation behavior of exposed films. Results show that incorporation of colorant and increasing thickness exhibit low maximum weight uptake. Titanium dioxide as white colorant in films lowers the susceptibility of films to oxygen uptake but enhances physical degradation. Higher amount of pro-oxidant loading also contributes to faster degradation. Opaque films are characterized by low tensile strength and high elastic modulus. Decreasing the thickness contributes to lower tensile strength of films. Thermally aged films with colorant and low thickness promote enhanced degradation.

  13. Relation between molecule ionization energy, film thickness and morphology of two indandione derivatives thin films

    NASA Astrophysics Data System (ADS)

    Grzibovskis, Raitis; Vembris, Aivars; Pudzs, Kaspars

    2016-08-01

    Nowadays most organic devices consist of thin (below 100 nm) layers. Information about the morphology and energy levels of thin films at such thickness is essential for the high efficiency devices. In this work we have investigated thin films of 2-(4-[N,N-dimethylamino]-benzylidene)-indene-1,3-dione (DMABI) and 2-(4-(bis(2-(trityloxy)ethyl)amino)benzylidene)-2H-indene-1,3-dione (DMABI-6Ph). DMABI-6Ph is the same DMABI molecule with attached bulky groups which assist formation of amorphous films from solutions. Polycrystalline structure was obtained for the DMABI thin films prepared by thermal evaporation in vacuum and amorphous structure for the DMABI-6Ph films prepared by spin-coating method. Images taken by SEM showed separate crystals or islands at the thickness of the samples below 100 nm. The ionization energy of the studied compounds was determined using photoemission yield spectroscopy. A vacuum level shift of 0.40 eV was observed when ITO electrode was covered with the thin film of the organic compound. Despite of the same active part of the investigated molecules the ITO/DMABI interface is blocking electrons while ITO/DMABI-6Ph interface is blocking holes.

  14. Magnetic Probe Construction using Thick-film Technology

    SciTech Connect

    Takahashi, H.; Sakakibara, S.; Kubota, Y.; and Yamada, H.

    2001-02-02

    Thick-film technology has been successfully adapted for the design and fabrication of magnetic probes of a new type suitable for use in the simultaneous ultra-high vacuum and high-temperature environment of a nuclear fusion device. The maximum usable temperature is expected to be around 900 degrees C. This new probe has a specific sensitivity (coupling area per unit volume) an order of magnitude higher than a conventional coil. The new probe in one implementation is capable of simultaneously measuring magnetic field in three orthogonal directions about a single spatial point and in two frequency ranges. Low-frequency coils have a measured coupling area of 296-323 cm squared and a frequency response of about 300 kHz. High-frequency coils have a design coupling area of 12-15 cm squared.

  15. LTCC Phase Shifters Based on Tunable Ferroelectric Composite Thick Films

    NASA Astrophysics Data System (ADS)

    Nikfalazar, M.; Kohler, C.; Heunisch, A.; Wiens, A.; Zheng, Y.; Schulz, B.; Mikolajek, M.; Sohrabi, M.; Rabe, T.; Binder, J. R.; Jakoby, R.

    2015-11-01

    This paper presents, the investigation of tunable components based on LTCC technology, implementing ferroelectric tunable thick-film dielectric. The tunable loaded line phase shifters are fabricated with metal-insulator-metal (MIM) varactors to demonstrate the capabilities of this method for packaging of the tunable components. The MIM varactors consist of one tunable dielectric paste layer that is printed between two silver layers. The tunable ferroelectric paste is optimized for LTCC sintering temperature around 850°C. The phase shifters are fabricated in two different process. They were achieved a figure of merit of 24°/dB (phase shift 192°) at 3 GHz and 18°/dB (phase shift 98°) at 4.4 GHz by using seven unit cells that each unit cell consisting of two MIM varactors.

  16. Development of metal oxide impregnated stilbite thick film ethanol sensor

    NASA Astrophysics Data System (ADS)

    Mahabole, M. P.; Lakhane, M. A.; Choudhari, A. L.; Khairnar, R. S.

    2016-05-01

    This paper presents the study of the sensing efficiency of Titanium oxide/ Stilbite and Copper oxide /Stilbite composites towards detection of hazardous pollutants like ethanol. Stilbite based composites are prepared by physically mixing zeolite with metal oxides namely TiO2 and CuO with weight ratios of 25:75, 50:50 and 75:25. The resulting sensor materials are characterized by X-ray diffraction and Fourier Transform Infrared Spectroscopy techniques. Composite sensors are fabricated in the form of thick film by using screen printing technique. The effect of metal oxide concentration on various ethanol sensing parameters such as operating temperature, maximum uptake capacity and response/recovery time are investigated. The results indicate that metal oxide impregnated stilbite composites have great potential as low temperature ethanol sensor.

  17. Electroplating moulds using dry film thick negative photoresist

    NASA Astrophysics Data System (ADS)

    Kukharenka, E.; Farooqui, M. M.; Grigore, L.; Kraft, M.; Hollinshead, N.

    2003-07-01

    This paper reports on progress on the feasibility of fabricating moulds for electroplating using Ordyl P-50100 (negative) acrylate polymer based dry film photoresist, commercially available from Elga Europe (http://www.elgaeurope.it). We used this photoresist as an alternative to SU8 negative epoxy based photoresist, which is very difficult to process and remove after electroplating (Lorenz et al 1998 Microelectron. Eng. 41/42 371-4, Eyre et al 1998 Proc. MEMS'98 (Heidelberg) (Piscataway, NJ: IEEE) pp 218-22). Ordyl P-50100 is easy to work with and can be easily removed after processing. A single layer of Ordyl P-50100 was deposited by lamination up to 20 µm thickness. Thicker layers (200 µm and more) can be achieved with multilayer lamination using a manual laminator. For our applications we found that Ordyl P-50100 dry film photoresist is a very good alternative to SU8 for the realization of 100 µm high moulds. The results presented will open up new possibilities for low-cost LIGA-type processes for MEMS applications.

  18. Holographic recording properties in thick films of ULSH-500 photopolymer

    NASA Astrophysics Data System (ADS)

    Waldman, David A.; Li, H.-Y. S.; Cetin, Erdem A.

    1998-06-01

    The photopolymer holographic recording materials, ULSH-500, based upon cationic ring-opening polymerization, has been further optimized for recording in an increased film thickness of 200 micrometers . The dynamic range attained, at least M/# equals 16, is substantially greater than previously reported, while concurrently the inherent low transverse shrinkage and high sensitivity characteristics of the material have been retained. Dynamic range or cumulative grating strength, (Sigma) (eta) i0.5, has been determined from co-locationally recorded peristrophic and angle multiplexed plane-wave gratings which exhibit low diffraction efficiencies between about 0.1 and 0.2%. Good Bragg selectivity consistent with the imaged thickness and sinc2 function behavior is observed for the multiplexed holograms, and both the angular response and the diffraction efficiency are stable without the need for post-imaging fixing procedures. Sensitivity is in the range of 1 to 10 cm/mJ, and the refractive index modulation achievable during consumption of the accessible dynamic range is n1 equals 1.3 X 10-2 at the read wavelength of 514.5 nm.

  19. Magnetic thin film deposition with pulsed magnetron sputtering: deposition rate and film thickness distribution

    NASA Astrophysics Data System (ADS)

    Ozimek, M.; Wilczyński, W.; Szubzda, B.

    2016-02-01

    The goal of conducted study was an experimental determining the relations between technological parameters of magnetron sputtering process on deposition rate (R) and thickness uniformity of magnetic thin films. Planar Ni79Fei6Mo5 target with a diameter of 100 mm was sputtered in argon (Ar) atmosphere. Deposition rate was measured in a function of gas pressure, target power and target-substrate distance. The highest value of R≈280 nmmin-1. The obtained results in deposition rate of magnetic film were compared to deposition rate of cooper (Cu), aluminum (Al), titanium (Ti) and titanium oxide (TiOx) and the deposition rate of Ni-Fe alloy were higher that Al and Ti. The film thickness distribution was measured for radial distance from the target centre ranging up to 60 mm and target-substrate distance ranging form 70 to 115 mm. Among others it was stated that for the larger value of target-substrate distance the larger uniform of film thickness are obtained.

  20. Reduced temperature-dependent thermal conductivity of magnetite thin films by controlling film thickness

    PubMed Central

    2014-01-01

    We report on the out-of-plane thermal conductivities of epitaxial Fe3O4 thin films with thicknesses of 100, 300, and 400 nm, prepared using pulsed laser deposition (PLD) on SiO2/Si substrates. The four-point probe three-omega (3-ω) method was used for thermal conductivity measurements of the Fe3O4 thin films in the temperature range of 20 to 300 K. By measuring the temperature-dependent thermal characteristics of the Fe3O4 thin films, we realized that their thermal conductivities significantly decreased with decreasing grain size and thickness of the films. The out-of-plane thermal conductivities of the Fe3O4 films were found to be in the range of 0.52 to 3.51 W/m · K at 300 K. For 100-nm film, we found that the thermal conductivity was as low as approximately 0.52 W/m · K, which was 1.7 to 11.5 order of magnitude lower than the thermal conductivity of bulk material at 300 K. Furthermore, we calculated the temperature dependence of the thermal conductivity of these Fe3O4 films using a simple theoretical Callaway model for comparison with the experimental data. We found that the Callaway model predictions agree reasonably with the experimental data. We then noticed that the thin film-based oxide materials could be efficient thermoelectric materials to achieve high performance in thermoelectric devices. PMID:24571956

  1. The application of the barrier-type anodic oxidation method to thickness testing of aluminum films.

    PubMed

    Chen, Jianwen; Yao, Manwen; Xiao, Ruihua; Yang, Pengfei; Hu, Baofu; Yao, Xi

    2014-09-01

    The thickness of the active metal oxide film formed from a barrier-type anodizing process is directly proportional to its formation voltage. The thickness of the consumed portion of the metal film is also corresponding to the formation voltage. This principle can be applied to the thickness test of the metal films. If the metal film is growing on a dielectric substrate, when the metal film is exhausted in an anodizing process, because of the high electrical resistance of the formed oxide film, a sudden increase of the recorded voltage during the anodizing process would occur. Then, the thickness of the metal film can be determined from this voltage. As an example, aluminum films are tested and discussed in this work. This method is quite simple and is easy to perform with high precision. PMID:25273741

  2. The application of the barrier-type anodic oxidation method to thickness testing of aluminum films

    NASA Astrophysics Data System (ADS)

    Chen, Jianwen; Yao, Manwen; Xiao, Ruihua; Yang, Pengfei; Hu, Baofu; Yao, Xi

    2014-09-01

    The thickness of the active metal oxide film formed from a barrier-type anodizing process is directly proportional to its formation voltage. The thickness of the consumed portion of the metal film is also corresponding to the formation voltage. This principle can be applied to the thickness test of the metal films. If the metal film is growing on a dielectric substrate, when the metal film is exhausted in an anodizing process, because of the high electrical resistance of the formed oxide film, a sudden increase of the recorded voltage during the anodizing process would occur. Then, the thickness of the metal film can be determined from this voltage. As an example, aluminum films are tested and discussed in this work. This method is quite simple and is easy to perform with high precision.

  3. In vivo tear film thickness measurement and tear film dynamics visualization using spectral domain optical coherence tomography.

    PubMed

    Aranha Dos Santos, Valentin; Schmetterer, Leopold; Gröschl, Martin; Garhofer, Gerhard; Schmidl, Doreen; Kucera, Martin; Unterhuber, Angelika; Hermand, Jean-Pierre; Werkmeister, René M

    2015-08-10

    Dry eye syndrome is a highly prevalent disease of the ocular surface characterized by an instability of the tear film. Traditional methods used for the evaluation of tear film stability are invasive or show limited repeatability. Here we propose a new non-invasive fully automated approach to measure tear film thickness based on spectral domain optical coherence tomography and on an efficient delay estimator. Silicon wafer phantom were used to validate the thickness measurement. The technique was applied in vivo in healthy subjects. Series of tear film thickness maps were generated, allowing for the visualization of tear film dynamics. Our results show that the in vivo central tear film thickness measurements are precise and repeatable with a coefficient of variation of about 0.65% and that repeatable tear film dynamics can be observed. The presented approach could be used in clinical setting to study patients with dry eye disease and monitor their treatments. PMID:26367956

  4. Elastohydrodynamic film thickness formula based on X-ray measurements with a synthetic paraffinic oil

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Parker, R. J.; Zaretsky, E. V.

    1973-01-01

    An empirical elastohydrodynamic film thickness formula for heavily loaded contacts based upon X-ray film thickness measurements made with a synthetic paraffinic oil is presented. The deduced relation was found to adequately reflect the high load dependence exhibited by the measured minimum film thickness data at high Hertizian contact stresses, that is, above 1.04 x 10 to the ninth N/sq m (150,000 psi). Comparisons were made with the numerical results from a theoretical isothermal film thickness formula. The effects of changes in contact geometry, material, and lubricant properties on the form of the empirical model are also discussed.

  5. Thickness microscopy based on photothermal radiometry for the measurement of thin films.

    PubMed

    Wang, Liping; Prekel, Helmut; Liu, Hengbiao; Deng, Yanzhuo; Hu, Jiming; Goch, Gert

    2009-03-01

    The photothermal detection technique is an innovative and non-contact method to investigate the properties of films on workpieces. This paper describes a novel experimental set-up for thickness microscopy based on photothermal radiometry. The correlation between the thermal wave signal and the film thickness is deduced and evaluated to determine the film thickness with a lateral resolution of less than 1mm. Results indicate that the thickness microscopy is a useful method to characterize thin films and has the potential to be applied in-process. PMID:19046925

  6. Non-linear dynamics of inlet film thickness during unsteady rolling process

    NASA Astrophysics Data System (ADS)

    Fu, Kuo; Zang, Yong; Gao, Zhiying; Qin, Qin; Wu, Diping

    2016-05-01

    The inlet film thickness directly affects film and stress distribution of rolling interfaces. Unsteady factors, such as unsteady back tension, may disturb the inlet film thickness. However, the current models of unsteady inlet film thickness lack unsteady disturbance factors and do not take surface topography into consideration. In this paper, based on the hydrodynamic analysis of inlet zone an unsteady rolling film model which concerns the direction of surface topography is built up. Considering the small fluctuation of inlet angle, absolute reduction, reduction ratio, inlet strip thickness and roll radius as the input variables and the fluctuation of inlet film thickness as the output variable, the non-linear relationship between the input and output is discussed. The discussion results show that there is 180° phase difference between the inlet film thickness and the input variables, such as the fluctuant absolute reduction, the fluctuant reduction ratio and non-uniform inlet strip thickness, but there is no phase difference between unsteady roll radius and the output. The inlet angle, the steady roll radius and the direction of surface topography have significant influence on the fluctuant amplitude of unsteady inlet film thickness. This study proposes an analysis method for unsteady inlet film thickness which takes surface topography and new disturbance factors into consideration.

  7. Dissociative electron attachment and charging of SF6 adsorbed on rare-gas films

    NASA Astrophysics Data System (ADS)

    Weik, Fritz; Illenberger, Eugen

    1998-10-01

    Electron stimulated desorption (ESD) of fragment ions in the energy range between 0 and 18 eV from SF6 adsorbed on rare-gas films (Kr, Xe) is reported. The ESD results are compared with previous experiments on dissociative electron attachment (DA) to gas-phase SF6. At energies characteristic for the respective rare-gas substrate strong resonant enhancements in the ESD yield of F- are observed. This enhancement is explained by the appearance of an "electron-exciton complex" in the rare-gas film (the analogue to the anionic Feshbach resonances in single atoms) which couples to the first dipole allowed excitation of the SF6 molecule. After electron and energy transfer, the highly excited SF6*- ion dissociates at the surface resulting in the desorption of F- fragments. At low electron energies (in the range from 0 to 0.6 eV) charging of the rare-gas film covered with SF6 is observed. From these experiments a charging cross section of 2.1(±1.8)×10-15 cm2 is derived.

  8. Thermodynamic and dynamic characteristics of hydroxypropylmethylcellulose adsorbed films at the air-water interface.

    PubMed

    Pérez, Oscar E; Sánchez, Cecilio Carrera; Rodríguez Patino, Juan M; Pilosof, Ana M R

    2006-01-01

    Surface pressure isotherms and structural and surface dilatational properties of three hydroxypropylmethycelluloses (HPMCs, called E4M, E50LV, and F4M) adsorbed films at the air-water interface were determined. In this work we present evidence that HPMC molecules are able to diffuse and saturate the air-water interface at very low concentrations in the bulk phase. As bulk concentration increased, structural changes at a molecular level occurred at the interface. These changes corresponded to transition from an expanded structure (structure I) to a condensed one (structure II). When the surface concentration of HPMC was high enough, the collapse of the monolayer was observed. The three HPMCs formed very elastic films at the air-water interface, even at low surface pressures. E4M showed features that make it unique. For instance it showed the highest surface activity, mainly at low bulk concentrations (<10(-4) wt %). The differences observed in surface activity may be attributed to differences in the hydroxypropyl molar substitution and molecular weight of HPMC. All three HPMCs formed films of similar viscoelasticity and elastic dilatational modulus, which can be accounted for by their similar degree of methyl substitution. PMID:16398540

  9. Sputtering and secondary ion emission properties of alkali metal films and adsorbed monolayers

    SciTech Connect

    Krauss, A R; Gruen, D M

    1980-01-01

    The secondary ion emission of alkali metal adsorbed monlayer and multilayer films has been studied. Profiling with sub-monolayer resolution has been performed by Auger, x-ray photoemission and secondary ion mass spectroscopy. Characteristic differences in the sputtering yields, and ion fraction have been observed which are associated with both the surface bonding properties and the mechanism leading to the formation of secondary ions. By sputtering with a negative bias applied to the sample, positive secondary ions are returned to the surface, resulting in a reduced sputter-induced erosion rate. Comparison with the results obtained with K and Li overlayers sputtered without sample bias provides an experimental value of both the total and secondary ion sputtering yields. The first and second monolayers can be readily identified and the first monolayer exhibits a lower sputtering yield and higher secondary ion fraction. This result is related to adsorption theory and measured values are compared with those obtained by thermal desorption measurements.

  10. Friction and transfer of copper, silver, and gold to iron in the presence of various adsorbed surface films

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1979-01-01

    Sliding friction experiments were conducted with the noble metals copper, silver, and gold and two binary alloys of these metals contacting iron in the presence of various adsorbates including, oxygen, methyl mercaptan, and methyl chloride. A pin on disk specimen configuration was used with a load of 100 grams, sliding velocity of 60 mm/min; at 25 C with the surfaces saturated with the adsorbates. Auger emission spectroscopy was used to monitor surface films. Results of the experiments indicate that friction and transfer characteristics are highly specific with respect to both the noble metal and surface film present. With all three metals and films transfer of the noble metal to iron occurred very rapidly. With all metals and films transfer of the noble metal to iron continuously increased with repeated passes except for silver and copper sliding on iron sulfide.

  11. Method and system for producing sputtered thin films with sub-angstrom thickness uniformity or custom thickness gradients

    DOEpatents

    Folta, James A.; Montcalm, Claude; Walton, Christopher

    2003-01-01

    A method and system for producing a thin film with highly uniform (or highly accurate custom graded) thickness on a flat or graded substrate (such as concave or convex optics), by sweeping the substrate across a vapor deposition source with controlled (and generally, time-varying) velocity. In preferred embodiments, the method includes the steps of measuring the source flux distribution (using a test piece that is held stationary while exposed to the source), calculating a set of predicted film thickness profiles, each film thickness profile assuming the measured flux distribution and a different one of a set of sweep velocity modulation recipes, and determining from the predicted film thickness profiles a sweep velocity modulation recipe which is adequate to achieve a predetermined thickness profile. Aspects of the invention include a practical method of accurately measuring source flux distribution, and a computer-implemented method employing a graphical user interface to facilitate convenient selection of an optimal or nearly optimal sweep velocity modulation recipe to achieve a desired thickness profile on a substrate. Preferably, the computer implements an algorithm in which many sweep velocity function parameters (for example, the speed at which each substrate spins about its center as it sweeps across the source) can be varied or set to zero.

  12. Effect of Magnetic Film Thickness on the Spatial Resolution of Magnetic Force Microscope Tips

    NASA Astrophysics Data System (ADS)

    Nagano, Katsumasa; Tobari, Kousuke; Ohtake, Mitsuru; Futamoto, Masaaki

    2011-07-01

    Magnetic force microscope (MFM) tips were prepared by coating commercial atomic force microscope (AFM) tips of 5 nm radius with Co and CoCrPt magnetic thin films varying the thickness in a range of 10-80 nm. The structural and the magnetic properties of coated magnetic thin films were investigated by scanning electron microscopy, AFM, X-ray diffraction, and vibrating sample magnetometry. The tip radius and the film surface roughness increase with increasing the film thickness. With increasing the film thickness, the MFM signal sensitivity increases, whereas the resolution decreases due to increase of tip radius. The MFM observation resolutions of 10 nm and 23 nm are obtained with the tips coated with 20-nm-thick Co and 40-nm-thick CoCrPt films, respectively. The MFM resolution is influenced by both the tip radius and the magnetic moment of coated material.

  13. On-Line Measurement of Lubricant Film Thickness Using Ultrasonic Reflection Coefficients

    SciTech Connect

    Drinkwater, B.W.; Dwyer-Joyce, R.S.; Harper, P.

    2004-02-26

    The ultrasonic reflectivity of a lubricant layer between two solid bodies depends on the ultrasonic frequency, the acoustic properties of the liquid and solid, and the layer thickness. In this paper, ultrasonic reflectivity measurements are used as a method for determining the thickness of lubricating films in bearing systems. An ultrasonic transducer is positioned on the outside of a bearing shell such that the wave is focused on the lubricant film layer. For a particular lubricant film the reflected pulse is processed to give a reflection coefficient spectrum. The lubricant film thickness is then obtained from either the layer stiffness or the resonant frequency. The method has been validated using static fluid wedges and the elastohydrodynamic film formed between a ball sliding on a flat. Film thickness values in the range 50-500 nm were recorded which agreed well with theoretical film formation predictions.

  14. 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.

  15. Difference in Surface Properties between Insoluble Monolayer and Adsorbed Film from Kinetics of Water Evaporation and BAM Image.

    PubMed

    Moroi, Yoshikiyo; Rusdi, Muhammad; Kubo, Izumi

    2004-05-20

    The evaporation rate of water molecules across three kinds of interfaces (air/water interface (1), air/surfactant solution interface (2), and air/water interface covered by insoluble monolayer (3)) was examined using a remodeled thermogravimetric balance. There was no difference in both the evaporation rate and the activation energy for the first two interfaces for three types of surfactant solutions below and above the critical micelle concentration (cmc). This means that the molecular surface area from the Gibbs surface excess has nothing to do with the evaporation rate. In the third case, the insoluble monolayer of 1-heptadecanol decreased the evaporation rate and increased the activation energy, indicating a clear difference between an insoluble monolayer and an adsorbed film of soluble surfactant. This difference was substantiated by BAM images, too. The images of three surfactant solution interfaces were similar to that of just the water surface, while distinct structures of molecular assemblies were observed for the insoluble monolayer. The concentration profile of water molecules in an air/liquid interfacial region was derived by Fix's second law. The profile indicates that a definite layer just beneath the air/liquid interface of the surfactant solution is made mostly of water molecules and that the layer thickness is a few times the root-mean-square displacement %@mt;sys@%%@rl;;@%2%@ital@%Dt%@rsf@%%@rlx@%%@mx@% of the water molecules. The thickness was found to be more than a few nanometers, as estimated from several relaxation times derived from the other kinetics than evaporation of amphiphilic molecules in aqueous systems and a maximum evaporation rate of purified water. PMID:18950121

  16. Influence of Thickness on Ethanol Sensing Characteristics of Doctor-bladed Thick Film from Flame-made ZnO Nanoparticles

    PubMed Central

    Liewhiran, Chaikarn; Phanichphant, Sukon

    2007-01-01

    ZnO nanoparticles were produced by flame spray pyrolysis (FSP) using zinc naphthenate as a precursor dissolved in toluene/acetonitrile (80/20 vol%). The particle properties were analyzed by XRD, BET, and HR-TEM. The sensing films were produced by mixing the particles into an organic paste composed of terpineol and ethyl cellulose as a vehicle binder and were fabricated by doctor-blade technique with various thicknesses (5, 10, 15 μm). The morphology of the sensing films was analyzed by SEM and EDS analyses. The gas sensing characteristics to ethanol (25-250 ppm) were evaluated as a function of film thickness at 400°C in dry air. The relationship between thickness and ethanol sensing characteristics of ZnO thick film on Al2O3 substrate interdigitated with Au electrodes were investigated. The effects of film thickness, as well as the cracking phenomenon, though, many cracks were observed for thicker sensing films. Crack widths increased with increasing film thickness. The film thickness, cracking and ethanol concentration have significant effect on the sensing characteristics. The sensing characteristics with various thicknesses were compared, showing the tendency of the sensitivity to ethanol decreased with increasing film thickness and response time. The relationship between gas sensing properties and film thickness was discussed on the basis of diffusively and reactivity of the gases inside the oxide films. The thinnest sensing film (5 μm) showed the highest sensitivity and the fastest response time (within seconds).

  17. Effects of film thickness on scintillation characteristics of columnar CsI:Tl films exposed to high gamma radiation doses

    NASA Astrophysics Data System (ADS)

    Shinde, Seema; Singh, S. G.; Sen, S.; Gadkari, S. C.

    2016-02-01

    Oriented columnar films of Tl doped CsI (CsI:Tl) of varying thicknesses from 50 μm to 1000 μm have been deposited on silica glass substrates by a thermal evaporation technique. The SEM micrographs confirmed the columnar structure of the film while the powder X-ray diffraction pattern recorded for the films revealed a preferred orientation of the grown columns along the <200> direction. Effects of high energy gamma exposure up to 1000 Gy on luminescence properties of the films were investigated. Results of radio-luminescence, photo-luminescence and scintillation studies on the films are compared with those of a CsI:Tl single crystal with similar thickness. A possible correlation between the film thicknesses and radiation damage in films has been observed.

  18. 4-Mercaptopyridine adsorbed on pure palladium island films: A combined SERS and DFT investigation

    NASA Astrophysics Data System (ADS)

    Guo, Hao; Ding, Li; Zhang, Tianjie; Mo, Yujun

    2013-03-01

    Surface-enhanced Raman scattering (SERS) can provide vibrational information with molecular specificity and potential single-molecule sensitivity. SERS studies on pure transition metals, however, remain challenging due to the weak SERS activity of transition metals compared to coinage metals. Here we fabricated alumina-supported Pd island films by depositing laser-ablated Pd colloids onto an Al substrate. Robust SERS signal employing 4-mercaptopyridine (4-Mpy) as a probe was registered from the as-prepared films. The adsorption information of 4-Mpy molecules such as orientation and coordinating site was discussed in detail based on SERS data. It was inferred that 4-Mpy adsorbs via its sulfur atom to Pd surface with a tilted binding configuration. The Raman wavenumber and intensity of an adsorption model including one 4-Mpy and Pd atom were computed using density functional theory (DFT) at the Beck's three-parameter Lee-Yang-Parr (B3LYP) level with the LANL2DZ basis set. The simulated Raman spectrum was in good agreement with the experimental one except for the relative intensity. The current investigation could be helpful to gain a comprehensive understanding of SERS.

  19. Thickness Measurement, Rate Control And Automation In Thin Film Coating Technology

    NASA Astrophysics Data System (ADS)

    Pulker, H. K.

    1983-11-01

    There are many processes known for fabricating thin films/1, 2.Among them the group of physical vapor deposition processes comprising evaporation, sputtering and ion plating has received special attention.Especially evaporation but also the other PVD techniques are widely used to deposit various single and multilayer coatings for optical and electrical thin film applications/3,4/.A large number of parameters is important in obtaining the required film properties in a reproducible manner when depositing thin films by such processes.Amongst the many are the film thickness, the condensation rate,the substrate temperature,as well as the qualitative and the quantitative composition of the residual gas of primary importance.First of all the film thickness is a dimension which enters in practically all equations used to characterize a thin film. However,when discussing film thickness,definitions are required since there one has to distinguish between various types of thicknesses e.g.geometrical thickness,mass thickness and optical thickness.The geometrical thickness,often also called physical thickness,is defined as the step height between the substrate surface and the film surface.This step height multiplied by the refractive index of the film is termed the optical thickness and is expressed generally in integer multiples of fractional parts of a desired wavelength.The mass thickness finally is defined as the film mass per unit area obtained by weighing.Knowing the density and the optical data of a thin film its mass thickness can be converted into the corresponding geometrical as well as optical thickness.However,with ultrathin films ranging between a few and several atomic or molecular "layers"the concept of a film thickness may become senseless since often no closed film exists of such minor deposits.Although film thickness is a length,the measurement of it can,obviously,not be accomplished with conventional methods for length determinations but requires special

  20. Refractive index gradient measurement across the thickness of a dielectric film by the prism coupling method

    SciTech Connect

    Sokolov, Viktor I; Panchenko, Vladislav Ya; Seminogov, V N

    2012-08-31

    A method is proposed for measuring the refractive index gradient n(z) in nonuniformly thick dielectric films. The method is based on the excitation of waveguide modes in a film using the prism coupling technique and on the calculation of n(z) and film thickness H{sub f} with the help of the angular positions of the TE or TM modes. The method can be used for an arbitrary shape of the index modulation over the film thickness in the limit of a small gradient [{Delta} n(z)/n(z) || 1]. (laser applications and other topics in quantum electronics)

  1. Effect of thickness on electrical properties of SILAR deposited SnS thin films

    NASA Astrophysics Data System (ADS)

    Akaltun, Yunus; Astam, Aykut; Cerhan, Asena; ćayir, Tuba

    2016-03-01

    Tin sulfide (SnS) thin films of different thickness were prepared on glass substrates by successive ionic layer adsorption and reaction (SILAR) method at room temperature using tin (II) chloride and sodium sulfide aqueous solutions. The thicknesses of the films were determined using spectroscopic ellipsometry measurements and found to be 47.2, 65.8, 111.0, and 128.7nm for 20, 25, 30 and 35 deposition cycles respectively. The electrical properties of the films were investigated using d.c. two-point probe method at room temperature and the results showed that the resistivity was found to decrease with increasing film thickness.

  2. Dependence of Thermal Conductivity on Thickness in Single-Walled Carbon Nanotube Films.

    PubMed

    Lee, Kyung-Min; Shrestha, Ramesh; Dangol, Ashesh; Chang, Won Seok; Coker, Zachary; Choi, Tae-Youl

    2016-01-01

    Herein, we report experimentally dependence of thermal conductivity on thickness of single walled carbon nanotubes (SWNTs) thin films; the measurements are based on the micropipette thermal sensor technique. Accurate and well resolved measurements of thermal conductivity made by the micropipette sensor showed a correlated behavior of thickness and thermal conductivity of CNT films that thermal conductivity decreased as thickness increased. The thickness dependence is explained by reduction of mean free path (MFP), which is induced by more intertubular junctions in more dense-packed carbon nanotube (CNT) networks; the thicker SWCNT films were revealed to have higher density. PMID:27398564

  3. Thickness- and temperature-dependent magnetodynamic properties of yttrium iron garnet thin films

    SciTech Connect

    Haidar, M. Ranjbar, M.; Balinsky, M.; Dumas, R. K.; Khartsev, S.; Åkerman, J.

    2015-05-07

    The magnetodynamical properties of nanometer-thick yttrium iron garnet films are studied using ferromagnetic resonance as a function of temperature. The films were grown on gadolinium gallium garnet substrates by pulsed laser deposition. First, we found that the damping coefficient increases as the temperature increases for different film thicknesses. Second, we found two different dependencies of the damping on film thickness: at room temperature, the damping coefficient increases as the film thickness decreases, while at T = 8 K, we find the damping to depend only weakly on the thickness. We attribute this behavior to an enhancement of the relaxation of the magnetization by impurities or defects at the surfaces.

  4. Application of the Ultrasonic Oil Film Thickness Measurement System in Bearing Chambers

    NASA Astrophysics Data System (ADS)

    Zhong, Chong; Hu, Jian-ping; Liu, Zhen-xia; Lu, Ya-guo; Hao, Yu-ya

    2014-06-01

    The oil film thickness in aero-engine bearing chamber influences the heat transfer capacity of the bearing chamber wall, so measuring oil film thickness accuspeedly is essential to the design and thermal analysis of lubricating oil system. In this paper, software and hardware of an ultrasonic measurement system based on pulse echo technique, which measures the oil film thickness in bearing chamber, are established. The hardware system mainly consists of signal acquisition card, probe, delay block and the corresponding cables. Functions as measurement parameter setup, real-time display of measured waveforms, post-processing and so on are included in the measurement software. Finally, the oil film thickness of the wall is measured with the measurement system developed. Signal quality of the dynamic measurement is analyzed. Comparison and analysis of different oil film thickness under different rotation rates are conducted.

  5. Thick-film MEMS thermoelectric sensor fabricated using a thermally assisted lift-off process

    NASA Astrophysics Data System (ADS)

    Jia, Yuan; Cai, Haogang; Lin, Qiao

    2016-04-01

    This paper presents a thick-film microelectromechanical systems thermoelectric sensor fabricated by a low-temperature thermally assisted lift-off process. During the process, thick metal or semiconductor films experience controlled breakup due to thermal reflow of the underlying lithographically defined photoresist patterns, thereby facilitating the sacrificial removal of the photoresist. This enables rapid and reliable patterning of thick films that can otherwise be difficult to achieve by conventional processes. Experimental results with a sensor consisting of a 60-junction thick-film antimony-bismuth thermopile demonstrate an electric conductivity of 5.44×106 S/m and a Seebeck coefficient of 114 μV/K per junction, which are comparable to those obtained from bulk materials. Thus, the thick-film sensor can potentially allow low-noise, high-efficiency thermoelectric measurements.

  6. Structural, magnetic and transport properties of Co2FeAl Heusler films with varying thickness

    NASA Astrophysics Data System (ADS)

    Wang, Xiaotian; Li, Yueqing; Du, Yin; Dai, Xuefang; Liu, Guodong; Liu, Enke; Liu, Zhongyuan; Wang, Wenhong; Wu, Guangheng

    2014-08-01

    We report on a systematic study of the structural, magnetic properties and the anomalous Hall effect, in the Heusler alloy Co2FeAl (CFA) epitaxial films on MgO (001), as a function of film thickness. It was found that the epitaxial CFA films show a highly ordered B2 structure with an in-plane uniaxial magnetic anisotropy. The electrical transport properties reveal that the lattice and magnon scattering contributions to the longitudinal resistivity. Independent on the thickness of films, the anomalous Hall resistivity of CFA films is found to be dominated by skew scattering only. Moreover, the anomalous Hall resistivity shows weakly temperature dependent behavior, and its absolute value increases as the thickness decreases. We attribute this temperature insensitivity in the anomalous Hall resistivity to the weak temperature dependent of tunneling spin-polarization in the CFA films, while the thickness dependence behavior is likely due to the increasing significance of interface or free surface electronic states.

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

    PubMed

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

    2013-05-14

    Conventional composite sol-gel method has been modified to enhance the piezoelectric performance of ceramic thick films. Lead zirconate titanate (PZT) and lead magnesium niobate-lead titanate (PMN-PT) thick films were fabricated using the modified sol-gel method for ultrasonic transducer applications. In this work, piezoresponse force microscopy was employed to evaluate the piezoelectric characteristics of PZT and PMN-PT composite sol-gel thick films. The images of the piezoelectric response and the strain-electric field hysteresis loop behavior were measured. The effective piezoelectric coefficient (d33,eff) of the films was determined from the measured loop data. It was found that the effective local piezoelectric coefficient of both PZT and PMN-PT composite films is comparable to that of their bulk ceramics. The promising results suggest that the modified composite sol-gel method is a promising way to prepare the high-quality, crack-free ceramic thick films. PMID:23798771

  8. Thickness Dependence of Fluorescence Dynamics in Thin and Ultrathin Polystyrene Films

    NASA Astrophysics Data System (ADS)

    Tateishi, Yohei; Okada, Yohei; Tanaka, Keiji; Nagamura, Toshihiko

    2008-03-01

    Fluorescence dynamics such as lifetime and rotational relaxation time for 6-(N-(7-nitrobenz-2-oxa-1,3- diazol-4-yl)amino) hexanoic acid (NBD) in polystyrene (PS) solid was examined as a function of film thickness, t. Both times decreased with decreasing thickness once the film became thinner than a critical value, to. Interestingly, in the case of ultrathin films, both times were insensitive to the film thickness. In addition, fluorescence intensity per unit thickness also decreased with decreasing thickness at t < to, meaning that the fluorescence quantum yield was dependent on the thickness at t < to. These results could be explained in terms of a simple three-layer model composed of surface, bulk and interfacial layers.

  9. Treasure of the Past VII: Measurement of the Thickness and Refractive Index of Very Thin Films and the Optical Properties of Surfaces by Ellipsometry1

    PubMed Central

    McCrackin, Frank L.; Passaglia, Elio; Stromberg, Robert R.; Steinberg, Harold L.

    2001-01-01

    The use of the ellipsometer for the measurement of the thickness and refractive index of very thin films is reviewed. The Poincaré sphere representation of the state of polarization of light is developed and used to describe the reflection process. Details of the operation of the ellipsometer are examined critically. A computational method is presented by which the thickness of a film of known refractive index on a reflecting substrate of known optical constants may be calculated directly from the ellipsometer readings. A method for computing both the refractive index and thickness of an unknown film is also developed. These methods have been applied to the determination of the thickness of an adsorbed water layer on chromium ferrotype plates and on gold surfaces. In the former case the thickness was 23 to 27 Å, and in the latter was 2 to 5 Å. The measurement of the thickness and refractive index of barium fluoride films evaporated on chromium ferrotype surfaces is used as an illustration of the simultaneous determination of these two quantities.

  10. Film Thickness and Flow Properties of Resin-Based Cements at Different Temperatures

    PubMed Central

    Bagheri, R

    2013-01-01

    Statement of Problem: For a luting agent to allow complete seating of prosthetic restorations, it must obtain an appropriate flow rate maintaining a minimum film thickness. The performance of recently introduced luting agents in this regard has not been evaluated. Purpose: To measure and compare the film thickness and flow properties of seven resin-containing luting cements at different temperatures (37°C, 25°C and10°C). Material and Methods: Specimens were prepared from five resin luting cements; seT (SDI), Panavia F (Kuraray), Varioloink II (Ivoclar), Maxcem (Kerr), Nexus2 (Kerr) and two resin-modified glass-ionomer luting cements (RM-GICs); GC Fuji Plus (GC Corporation), and RelyX Luting 2 (3 M/ESPE). The film thickness and flow rate of each cement (n=15) was determined using the test described in ISO at three different temperatures. Results: There was a linear correlation between film thickness and flow rate for most of the materials. Cooling increased fluidity of almost all materials while the effect of temperature on film thickness was material dependent. At 37°C, all products revealed a film thickness of less than 25µm except for GC Fuji Plus. At 25°C, all cements produced a film thickness of less than 27 µm except for seT. At 10°C, apart from seT and Rely X Luting 2, the remaining cements showed a film thickness smaller than 20 µm. Conclusion: Cooling increased fluidity of almost all materials, however. the film thickness did not exceed 35 µm in either condition, in spite of the lowest film thickness being demonstrated at the lowest temperature. PMID:24724120

  11. Structure and laser-fabrication mechanisms of microcones on silver films of variable thickness

    NASA Astrophysics Data System (ADS)

    Danilov, P. A.; Zayarny, D. A.; Ionin, A. A.; Kudryashov, S. I.; Nguyen, T. T. H.; Rudenko, A. A.; Saraeva, I. N.; Kuchmizhak, A. A.; Vitrik, O. B.; Kulchin, Yu. N.

    2016-04-01

    Submicron dimensions, nanoscale crystalline structure, and fabrication mechanisms of microcones on silver films of variable (50-380 nm) thickness deposited onto glass substrates by single strongly focused femtosecond laser pulses of different fluences are experimentally studied using scanning electron microscopy. Fabrication mechanisms for nanoholes and microcones are discussed for films of the different thickness, as well as the extraordinary shapes of their constituent nanocrystallites, strongly elongated along the melt flow direction in thin films.

  12. Measuring the Thickness and Elastic Properties of Electroactive Thin-Film Polymers Using Platewave Dispersion Data

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Lih, Shyh-Shiuh; El-Azab, A.; Mal, Ajit K.

    1996-01-01

    Electroactive thin-film polymers are candidate sensors and actuators materials. They are also finding significant potential in muscle mechanisms and microelectromechanical systems (MEMS). In these applications, polymer thin films of thickness varying between 20 and 300 micrometers are utilized. The authors are currently studying the potential use of platewave dispersion curve measurements as an effective gauging tool for electroactive thin-film polymers.

  13. Thickness Dependence of Properties of ITO Films Deposited on PET Substrates.

    PubMed

    Kim, Seon Tae; Kim, Tae Gyu; Cho, Hyun; Yoon, Su Jong; Kim, Hye Sung; Kim, Jin Kon

    2016-02-01

    Indium tin oxide (ITO) films with various thicknesses from 104 nm to 513 nm were prepared onto polyethylene terephthalate (PET) substrates by using r.f. magnetron sputtering without intentionally heating the substrates. The structural, optical, and electrical properties of ITO films were investigated as a function of film thickness. It was found that the amorphous nature of the ITO film was dominant below the thickness of about 200 nm but the degree of the crystallinity increased with an increasing thickness above the thickness of about 250 nm, resulting in the increase of carrier concentration and therefore reducing the electrical resistivity from 5.1 x 10(-3) to 9.4 x 10(-4) omega x cm. The average transmittance (400-800 nm) of the ITO deposited PET substrates decreased as the film thickness was increasing and was above 80% for the thickness below 315 nm. The results show that the improvement of the film crystallinity with the film thickness contributes to the increase of the carrier concentration and the enhancement of the electrical conductivity. PMID:27433686

  14. Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of ultrathin block copolymer films.

    PubMed

    Huang, Changchun; Wen, Gangyao; Li, Jingdan; Wu, Tao; Wang, Lina; Xue, Feifei; Li, Hongfei; Shi, Tongfei

    2016-09-15

    Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of spin-coated polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films (<20nm thick) were mainly investigated by atomic force microscopy. Surface chemical analysis of the ultrathin films annealed for different times were performed using X-ray photoelectron spectroscopy and contact angle measurement. With the annealing of acetone vapor, dewetting of the films with different thicknesses occur via the spinodal dewetting and the nucleation and growth mechanisms, respectively. The PS-b-PMMA films rupture into droplets which first coalesce into large ones to reduce the surface free energy. Then the large droplets rupture into small ones to increase the contact area between PMMA blocks and acetone molecules resulting from ultimate migration of PMMA blocks to droplet surface, which is a novel dewetting process observed in spin-coated films for the first time. PMID:27309943

  15. Noise properties of Pb/Cd-free thick film resistors

    NASA Astrophysics Data System (ADS)

    Witold Stadler, Adam; Kolek, Andrzej; Zawiślak, Zbigniew; Mleczko, Krzysztof; Jakubowska, Małgorzata; Rafał Kiełbasiński, Konrad; Młożniak, Anna

    2010-07-01

    Low-frequency noise spectroscopy has been used to examine noise properties of Pb/Cd-free RuO2- and CaRuO3-based thick films screen printed on alumina substrates. Experiments were performed in the temperature range 77-300 K and the frequency range 0.5-5000 Hz with multiterminal devices. The measured noise has been recognized as resistance noise that consists of background 1/f noise and components generated by several thermally activated noise sources (TANSs) of different activation energies. The total noise has been composed of the contributions generated in the resistive layer and in the resistive/conductive layers interface. These noise sources are non-uniformly distributed in the resistor volume. Noise intensity of new-resistive layers has been described by the noise parameter Cbulk. Pb/Cd-free layers turned out to be noisier than their Pb-containing counterparts; however, the removal of Pb and Cd from resistive composition is hardly responsible for the increase in the noise. In the case of RuO2 layers noise increases most likely due to larger grain size of RuO2 powder used to prepare resistive pastes. Information on the quality of the resistive-to-conductive layers interface occurred to be stored in the values of noise parameter Cint. Pb/Cd-free RuO2-based resistive pastes form well-behaved interfaces with various Ag-based conductive pastes. In contrast, CaRuO3-based paste forms bad contacts with AgPd terminations because the density of TANSs increases in the interface area.

  16. Characterization of Thin Film Dissolution in Water with in Situ Monitoring of Film Thickness Using Reflectometry.

    PubMed

    Yersak, Alexander S; Lewis, Ryan J; Tran, Jenny; Lee, Yung C

    2016-07-13

    Reflectometry was implemented as an in situ thickness measurement technique for rapid characterization of the dissolution dynamics of thin film protective barriers in elevated water temperatures above 100 °C. Using this technique, multiple types of coatings were simultaneously evaluated in days rather than years. This technique enabled the uninterrupted characterization of dissolution rates for different coating deposition temperatures, postdeposition annealing conditions, and locations on the coating surfaces. Atomic layer deposition (ALD) SiO2 and wet thermally grown SiO2 (wtg-SiO2) thin films were demonstrated to be dissolution-predictable barriers for the protection of metals such as copper. A ∼49% reduction in dissolution rate was achieved for ALD SiO2 films by increasing the deposition temperatures from 150 to 300 °C. ALD SiO2 deposited at 300 °C and followed by annealing in an inert N2 environment at 1065 °C resulted in a further ∼51% reduction in dissolution rate compared with the nonannealed sample. ALD SiO2 dissolution rates were thus lowered to values of wtg-SiO2 in water by the combination of increasing the deposition temperature and postdeposition annealing. Thin metal films, such as copper, without a SiO2 barrier corroded at an expected ∼1-2 nm/day rate when immersed in room temperature water. This measurement technique can be applied to any optically transparent coating. PMID:27308723

  17. Film Thickness Influences on the Thermoelectric Properties of NiCr/NiSi Thin Film Thermocouples

    NASA Astrophysics Data System (ADS)

    Chen, Y. Z.; Jiang, H. C.; Zhang, W. L.; Liu, X. Z.; Jiang, S. W.

    2013-06-01

    NiCr/NiSi thin film thermocouples (TFTCs) with a multi-layer structure were fabricated on Ni-based superalloy substrates (95 mm × 35 mm × 2 mm) by magnetron sputtering and electron beam evaporation. The five-layer structure is composed of NiCrAlY buffer layer (2 μm), thermally grown Al2O3 bond layer (200 nm), Al2O3 insulating layer (10 μm), NiCr/NiSi TFTCs (1 μm), and Al2O3 protective layer (500 nm). Influences of thermocouple layer thickness on thermoelectric properties were investigated. Seebeck coefficient of the samples with the increase in thermocouple layer thickness from 0.5 μm to 1 μm increased from 27.8 μV/°C to 33.8 μV/°C, but exhibited almost no change with further increase in thermocouple layer thickness from 1 μm to 2 μm. Dependence on temperature of the thermal electromotive force of the samples almost followed standard thermocouple characteristic curves when the thickness of the thermocouple layer was 1 μm and 2 μm. Sensitive coefficient K of the samples increased greatly with the increase in thickness of the thermocouple layer from 0.5 μm to 1 μm, but decreased insignificantly with the increase in thermocouple layer thickness from 1 μm to 2 μm, and continuously decreased with the increase in temperature. The sensitive coefficient and the stability of NiCr/NiSi TFTCs were both improved after annealing at 600°C.

  18. Correlation of Gear Surface Fatigue Lives to Lambda Ratio (Specific Film Thickness)

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy Lewis

    2013-01-01

    The effect of the lubrication regime on gear performance has been recognized, qualitatively, for decades. Often the lubrication regime is characterized by the specific film thickness being the ratio of lubricant film thickness to the composite surface roughness. Three studies done at NASA to investigate gearing pitting life are revisited in this work. All tests were done at a common load. In one study, ground gears were tested using a variety of lubricants that included a range of viscosities, and therefore the gears operated with differing film thicknesses. In a second and third study, the performance of gears with ground teeth and superfinished teeth were assessed. Thicker oil films provided longer lives as did improved surface finish. These datasets were combined into a common dataset using the concept of specific film thickness. This unique dataset of more 258 tests provides gear designers with some qualitative information to make gear design decisions.

  19. Temperature and layer thickness dependent in situ investigations on epindolidione organic thin-film transistors

    PubMed Central

    Lassnig, R.; Striedinger, B.; Jones, A.O.F.; Scherwitzl, B.; Fian, A.; Głowacl, E.D.; Stadlober, B.; Winkler, A.

    2016-01-01

    We report on in situ performance evaluations as a function of layer thickness and substrate temperature for bottom-gate, bottom-gold contact epindolidione organic thin-film transistors on various gate dielectrics. Experiments were carried out under ultra-high vacuum conditions, enabling quasi-simultaneous electrical and surface analysis. Auger electron spectroscopy and thermal desorption spectroscopy (TDS) were applied to characterize the quality of the substrate surface and the thermal stability of the organic films. Ex situ atomic force microscopy (AFM) was used to gain additional information on the layer formation and surface morphology of the hydrogen-bonded organic pigment. The examined gate dielectrics included SiO2, in its untreated and sputtered forms, as well as the spin-coated organic capping layers poly(vinyl-cinnamate) (PVCi) and poly((±)endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE, from the class of polynorbornenes). TDS and AFM revealed Volmer-Weber island growth dominated film formation with no evidence of a subjacent wetting layer. This growth mode is responsible for the comparably high coverage required for transistor behavior at 90–95% of a monolayer composed of standing molecules. Surface sputtering and an increased sample temperature during epindolidione deposition augmented the surface diffusion of adsorbing molecules and therefore led to a lower number of better-ordered islands. Consequently, while the onset of charge transport was delayed, higher saturation mobility was obtained. The highest, bottom-contact configuration, mobilities of approximately 2.5 × 10−3cm2/Vs were found for high coverages (50 nm) on sputtered samples. The coverage dependence of the mobility showed very different characteristics for the different gate dielectrics, while the change of the threshold voltage with coverage was approximately the same for all systems. An apparent decrease of the mobility with increasing coverage on the

  20. Non-contacting Measurement of Oil Film Thickness Between Loaded Metallic Gear Teeth

    NASA Astrophysics Data System (ADS)

    Cox, Daniel B.; Ceccio, Steven L.; Dowling, David R.

    2013-11-01

    The mechanical power transmission efficiency of gears is depends on the lubrication condition between gear teeth. While the lubrication levels can be generally predicted, an effective in-situ non-contacting measurement of oil film thicknesses between loaded metallic gear teeth has proved elusive. This study explores a novel oil film thickness measurement technique based on optical fluence, the light energy transmitted between loaded gear teeth. A gear testing apparatus that allowed independent control of gear rotation rate, load torque, and oil flow was designed and built. Film thickness measurements made with 5-inch-pitch-diameter 60-tooth spur gears ranged from 0.3 to 10.2 mil. These results are compared with film thickness measurements made in an earlier investigation (MacConochie and Cameron, 1960), as well as with predictions from two film thickness models: a simple two-dimensional squeezed oil film and the industry-accepted model as described by the American Gear Manufacturers Association (AGMA 925, 2003). In each case, the measured film thicknesses were larger than the predicted thicknesses, though these discrepancies might be attributed to the specifics the experiments and to challenges associated with calibrating the fluence measurements. [Sponsored by General Electric].

  1. Change in Tear Film Lipid Layer Thickness, Corneal Thickness, Volume and Topography after Superficial Cauterization for Conjunctivochalasis

    PubMed Central

    Chan, Tommy C. Y.; Ye, Cong; Ng, Paul KF; Li, Emmy Y. M.; Yuen, Hunter K. L.; Jhanji, Vishal

    2015-01-01

    We evaluated the change in tear film lipid layer thickness, corneal thickness, volume and topography after superficial cauterization of symptomatic conjunctivochalasis. Bilateral superficial conjunctival cauterization was performed in 36 eyes of 18 patients with symptomatic conjunctivochalasis. The mean age of patients (12 males, 6 females) was 68.6 ± 10.9 years (range: 44–83 years). Preoperatively, 28 eyes (77.8%) had grade 1 conjunctivochalasis, and 8 eyes (22.2%) had grade 2 conjunctivochalasis. At 1 month postoperatively, the severity of conjunctivochalasis decreased significantly (p < 0.001) and 29 eyes (80.6%) had grade 0 conjunctivochalasis whereas 7 eyes (19.4%) had grade 1 conjunctivochalasis. The mean Ocular Surface Disease Index score decreased from 31.5 ± 15.2 preoperatively to 21.5 ± 14.2 at the end of 1 month postoperatively (p = 0.001). There was a statistically significant increase in mean tear film lipid layer thickness 1 month after the surgery (49.6 ± 16.1 nm vs 62.6 ± 21.6 nm; p < 0.001). The central corneal thickness, thinnest corneal thickness and corneal volume decreased significantly postoperatively (p < 0.001). Our study showed that superficial conjunctival cauterization is an effective technique for management of conjunctivochalasis in the short term. An increase in tear film lipid layer thickness along with a decrease in corneal thickness and volume were observed after surgical correction of conjunctivochalasis. PMID:26184418

  2. Thickness dependence of the dielectric properties of thermally evaporated Sb2Te3 thin films

    NASA Astrophysics Data System (ADS)

    Ulutas, K.; Deger, D.; Yakut, S.

    2013-03-01

    Sb2Te3 thin films of different thickness (23 - 350 nm) were prepared by thermal evaporation technique. The thickness dependence of the ac conductivity and dielectric properties of the Sb2Te3 films have been investigated in the frequency range 10 Hz- 100 kHz and within the temperature range 293-373K. Both the dielectric constant epsilon1 and dielectric loss factor epsilon2 were found to depend on frequency, temperature and film thickness. The frequency and temperature dependence of ac conductivity (σac(ω)) has also been determined. The ac conductivity of our samples satisfies the well known ac power law; i.e., σac(ω) propto ωs where s<1 and independent of the film thickness. The temperature dependence of ac conductivity and parameter s is reasonably well interpreted by the correlated barrier hopping (CBH) model. The activation energies were evaluated for various thicknesses. The temperature coefficient of the capacitance (TCC) and permitivity (TCP) were determined as a function of the film thickness. The microstructure of the samples were analyzed using X-ray diffraction (XRD). This results are discussed on the base of the differences in their morphologies and thicknesses. The tendency for amorphization of the crystalline phases becomes evident as the film thickness increases.

  3. Third Sound in Superfluid 4He Films Adsorbed on Packed Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Menachekanian, Emin

    Third sound is studied for superfluid films of 4He adsorbed on multiwall carbon nanotubes packed into an annular resonator. The third sound is generated with mechanical oscillation of the cell, and detected with carbon bolometers. A filling curve at temperatures near 250 mK shows oscillations in the third sound velocity, with maxima at the completion of the 4th and 5th atomic layers. Sharp changes in the Q factor of the third sound are found at partial layer fillings. Temperature sweeps at a number of fill points show strong broadening effects on the Kosterlitz-Thouless (KT) transition, and rapidly increasing dissipation, in qualitative agreement with the predictions of Machta and Guyer. At the 4th layer completion there is a sudden reduction of the transition temperature TKT , and then a recovery back to linear variation with fill, although the slope is considerably smaller than the KT prediction. These effects might be related to changes in the gas-liquid coexistence regions.

  4. Realistic reflectance spectrum of thin films covering a transparent optically thick substrate

    SciTech Connect

    Cesaria, M. Caricato, A. P.; Martino, M.

    2014-07-21

    A spectrophotometric strategy is presented and discussed for calculating realistically the reflectance spectrum of an absorbing film deposited over a thick transparent or semi-transparent substrate. The developed route exploits simple mathematics, has wide range of applicability (high-to-weak absorption regions and thick-to-ultrathin films), rules out numerical and curve-fitting procedures as well as model-functions, inherently accounts for the non-measurable contribution of the film-substrate interface as well as substrate backside, and describes the film reflectance spectrum as determined by the experimental situation (deposition approach and parameters). The reliability of the method is tested on films of a well-known material (indium tin oxide) by deliberately changing film thickness and structural quality through doping. Results are found consistent with usual information yielded by reflectance, its inherent relationship with scattering processes and contributions to the measured total reflectance.

  5. Tailoring of Luminous Transmittance upon Switching for Thermochromic VO2 Films by Thickness Control

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Jin, Ping; Tazawa, Masato; Yoshimura, Kazuki

    2004-01-01

    The difference in luminous transmittance (Δ Tlum) upon switching of VO2 films strongly affects its solar controllability when used as a thermochromic window. It was found that Δ Tlum is controllable by film thickness. Optical calculation for a VO2 film on quartz glass revealed that the low-temperature semiconductor phase exhibits lower Tlum than the high-temperature metallic phase for thickness below 50 nm, while the relationship is reversed above 50 nm. The calculation was confirmed by film deposition and measurement. Maximum Δ Tlum is located near 80 nm. An enhanced Δ Tlum contributes largely to solar efficiency.

  6. Ptychographic Imaging of Branched Colloidal Nanocrystals Embedded in Free-Standing Thick Polystyrene Films

    NASA Astrophysics Data System (ADS)

    de Caro, Liberato; Altamura, Davide; Arciniegas, Milena; Siliqi, Dritan; Kim, Mee R.; Sibillano, Teresa; Manna, Liberato; Giannini, Cinzia

    2016-01-01

    Research on composite materials is facing, among others, the challenging task of incorporating nanocrystals, and their superstructures, in polymer matrices. Electron microscopy can typically image nanometre-scale structures embedded in thin polymer films, but not in films that are micron size thick. Here, X-ray Ptychography was used to visualize, with a resolution of a few tens of nanometers, how CdSe/CdS octapod-shaped nanocrystals self-assemble in polystyrene films of 24 ± 4 μm, providing a unique means for non-destructive investigation of nanoparticles distribution and organization in thick polymer films.

  7. Ptychographic Imaging of Branched Colloidal Nanocrystals Embedded in Free-Standing Thick Polystyrene Films

    PubMed Central

    De Caro, Liberato; Altamura, Davide; Arciniegas, Milena; Siliqi, Dritan; Kim, Mee R.; Sibillano, Teresa; Manna, Liberato; Giannini, Cinzia

    2016-01-01

    Research on composite materials is facing, among others, the challenging task of incorporating nanocrystals, and their superstructures, in polymer matrices. Electron microscopy can typically image nanometre-scale structures embedded in thin polymer films, but not in films that are micron size thick. Here, X-ray Ptychography was used to visualize, with a resolution of a few tens of nanometers, how CdSe/CdS octapod-shaped nanocrystals self-assemble in polystyrene films of 24 ± 4 μm, providing a unique means for non-destructive investigation of nanoparticles distribution and organization in thick polymer films. PMID:26775682

  8. Phase thickness approach for determination of thin film refractive index dispersion from transmittance spectra

    NASA Astrophysics Data System (ADS)

    Nenkov, M. R.; Pencheva, T. G.

    2008-06-01

    A novel approach for determination of refractive index dispersion n(λ ) and thickness d of thin films of negligible absorption and weak dispersion is proposed. The calculation procedure is based on determination of the phase thickness of the film in the spectral region of measured transmittance data. All points of measured spectra are included in the calculations. Barium titanate and titanium oxide thin films are investigated and their n(λ ) and d are calculated. The approach is validated using Swanepoel's method and it is found to be applicable for relatively thinner films when measured transmittance spectra have one minimum and one maximum only.

  9. Impressive electromagnetic shielding effects exhibited by highly ordered, micrometer thick polyaniline films

    NASA Astrophysics Data System (ADS)

    Mohan, Ranjini R.; Varma, Sreekanth J.; Sankaran, Jayalekshmi

    2016-04-01

    The present work highlights the remarkably high shielding effectiveness of about 68 dB, exhibited by highly ordered and doped polyaniline films, in the microwave frequency range 4-12 GHz, obtained by self-stabilized dispersion polymerization as the synthesis route. The observed shielding effectiveness is found to depend quite sensitively on the electrical conducting properties, which are predominantly controlled by the nature and concentration of the dopants. The structural and morphological characterization of the films using XRD and TEM techniques reveals surprisingly high extent of crystallinity, which contributes significantly towards enhancing the electrical conductivity of the films. Most of the available reports on the microwave response of conducting polymer film samples deal with much thicker films, compared to the micrometer thick films of the present studies. The shielding effectiveness of acid doped, micrometer thick polyaniline films reported in the present work far exceeds most of the previously reported values and meets the commercial requirements.

  10. Aging of the nanosized photochromic WO3 films and the role of adsorbed water in the photochromism

    NASA Astrophysics Data System (ADS)

    Gavrilyuk, A. I.

    2016-02-01

    Here it has been reported on aging of the nanosized WO3 film, which is revealed is continuous reduction of the photochromic sensitivity over time. Water molecules physically adsorbed on the film surface from ambient air form donor-acceptor and hydrogen bonds, changing gradually the adsorption state to chemisorption which prevents an access of organic molecules that serve as hydrogen donors by the photochromism. The mechanism of the process has been investigated and discussed. The role of water in the photochromism has been highlighted. The difference in the efficiency for being of a hydrogen donor in the photochromic process between water and organic molecules is discussed.

  11. In vivo tear film thickness measurement and tear film dynamics visualization using spectral domain OCT and an efficient delay estimator

    NASA Astrophysics Data System (ADS)

    Aranha dos Santos, Valentin; Schmetterer, Leopold; Gröschl, Martin; Garhofer, Gerhard; Werkmeister, René M.

    2016-03-01

    Dry eye syndrome is a highly prevalent disease of the ocular surface characterized by an instability of the tear film. Traditional methods used for the evaluation of tear film stability are invasive or show limited repeatability. Here we propose a new noninvasive approach to measure tear film thickness using an efficient delay estimator and ultrahigh resolution spectral domain OCT. Silicon wafer phantoms with layers of known thickness and group index were used to validate the estimator-based thickness measurement. A theoretical analysis of the fundamental limit of the precision of the estimator is presented and the analytical expression of the Cramér-Rao lower bound (CRLB), which is the minimum variance that may be achieved by any unbiased estimator, is derived. The performance of the estimator against noise was investigated using simulations. We found that the proposed estimator reaches the CRLB associated with the OCT amplitude signal. The technique was applied in vivo in healthy subjects and dry eye patients. Series of tear film thickness maps were generated, allowing for the visualization of tear film dynamics. Our results show that the central tear film thickness precisely measured in vivo with a coefficient of variation of about 0.65% and that repeatable tear film dynamics can be observed. The presented method has the potential of being an alternative to breakup time measurements (BUT) and could be used in clinical setting to study patients with dry eye disease and monitor their treatments.

  12. 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.

  13. Improvement of Film Thickness Uniformity in TFA-MOD Coated Conductors

    NASA Astrophysics Data System (ADS)

    Katayama, K.; Nakahata, K.; Yoshizumi, M.; Izumi, T.; Shiohara, Y.

    TFA-MOD process is expected to be promising for future applications since it can produce high performance YBCO coated conductors with low cost. The dip-coating is adopted as the coating process because of its simplicity and controllability of the overall film thickness. Dip-coated films have uniform thickness along longitudinal direction, but not necessary in transverse direction. In the case of thicker films, the more cracks form during processing at the thicker region near the edges generate and propagate mainly due to tensile and bending strain. So we have to suppress the thickness distribution in transverse direction for thicker films for high IC values. In this study, we found that the thickness distribution was firstly given by meniscus shape and then the solution flew down till it's dried. The solution in the center region drops more since it is slowly dried compared with the edge region. Then, we developed a drying process, which accelerates the drying by blowing hot gas to prevent the coated solutions from dropping. As a result, the thickness uniformity was improved; the thickness ratio of the thick region (edge) to the flat one (center) was improved from 1.35 to 1.07. Furthermore, we successfully produced ~1.5 μm thick films with high critical current density values (> 2MA/cm2) by the new coating process including the force drying step.

  14. Thickness dependence of Jc (0) in MgB2 films

    NASA Astrophysics Data System (ADS)

    Chen, Yiling; Yang, Can; Jia, Chunyan; Feng, Qingrong; Gan, Zizhao

    2016-06-01

    MgB2 superconducting films, whose thicknesses range from 10 nm to 8 μm, have been fabricated on SiC substrates by hybrid physical-chemical vapor deposition (HPCVD) method. It is the first time that the Tc and the Jc of MgB2 films are studied on such a large scale. It is found that with the increasing of thickness, Tc elevates first and then keeps roughly stable except for some slight fluctuations, while Jc (5 K, 0 T) experiences a sharp increase followed by a relatively slow fall. The maximum Jc (5 K, 0 T) = 2.3 × 108 A cm-2 is obtained for 100 nm films, which is the experimental evidence for preparing high-quality MgB2 films by HPCVD method. Thus, this work may provide guidance on choosing the suitable thickness for applications. Meanwhile, the films prepared by us cover ultrathin films, thin films and thick films, so the study on them will bring a comprehensive understanding of MgB2 films.

  15. Amorphous Indium Selenide Thin Films Prepared by RF Sputtering: Thickness-Induced Characteristics.

    PubMed

    Han, Myoung Yoo; Park, Yong Seob; Kim, Nam-Hoon

    2016-05-01

    The influence of indium composition, controlled by changing the film thickness, on the optical and electrical properties of amorphous indium selenide thin films was studied for the application of these materials as Cd-free buffer layers in CI(G)S solar cells. Indium selenide thin films were prepared using RF magnetron sputtering method. The indium composition of the amorphous indium selenide thin films was varied from 94.56 to 49.72 at% by increasing the film thickness from 30 to 70 nm. With a decrease in film thickness, the optical transmittance increased from 87.63% to 96.03% and Eg decreased from 3.048 to 2.875 eV. Carrier concentration and resistivity showed excellent values of ≥1015 cm(-3) and ≤ 10(4) Ω x cm, respectively. The conductivity type of the amorphous indium selenide thin films could be controlled by changing the film-thickness-induced amount of In. These results indicate the possibility of tuning the properties of amorphous indium selenide thin films by changing their composition for use as an alternate buffer layer material in CI(G)S solar cells. PMID:27483886

  16. Effects of artificially produced defects on film thickness distribution in sliding EHD point contacts

    NASA Technical Reports Server (NTRS)

    Cusano, C.; Wedeven, L. D.

    1981-01-01

    The effects of artificially produced dents and grooves on the elastohydrodynamic (EHD) film thickness profile in a sliding point contact were investigated by means of optical interferometry. The defects, formed on the surface of a highly polished ball, were held stationary at various locations within and in the vicinity of the contact region while the disk was rotating. It is shown that the defects, having a geometry similar to what can be expected in practice, can dramatically change the film thickness which exists when no defects are present in or near the contact. This change in film thickness is mainly a function of the position of the defects in the inlet region, the geometry of the defects, the orientation of the defects in the case of grooves, and the depth of the defect relative to the central film thickness.

  17. Film thickness measurement for spiral groove and Rayleigh step lift pad self-acting face seals

    NASA Technical Reports Server (NTRS)

    Dirusso, E.

    1982-01-01

    One Rayleigh step lift pad and three spiral groove self-acting face seal configurations were tested to measure film thickness and frictional torque as a function of shaft speed. The seals were tested at a constant face load of 73 N (16.4 lb) with ambient air at room temperature and atmospheric pressure as the fluid medium. The test speed range was from 7000 to 17,000 rpm. The measured film thickness was compared with theoretical data from mathematical models. The mathematical models overpredicted the measured film thickness at the lower speeds of the test speed range and underpredicted the measured film thickness at the higher speeds of the test speed range.

  18. Third Sound Generation in Superfluid 4He Films Adsorbed on Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Iaia, Vito; Menachekanian, Emin; Williams, Gary

    2014-03-01

    A technique is developed for generating third sound in superfluid 4He films coating the surface of multiwall carbon nanotubes. Third sound is a thickness and temperature wave of the helium film, and in our case we detect the temperature oscillations with a carbon resistance bolometer. The nanotubes are packed in an annular resonator that is vibrated with a mechanical shaker assembly consisting of a permanent magnet mounted on springs, and surrounded by a superconducting coil. The coil is driven with an oscillating current, vibrating the cell at that frequency. Sweeping the drive frequency over the range 100-200 Hz excites the resonant third sound mode of the cell, seen as a high-Q signal in the FFT analysis of the bolometer signal. A problem with our original cell was that the mechanical drive would also shake the dilution refrigerator cooling the cell to low temperatures, and increasing the drive would start to heat up the refrigerator and the cell, which were rigidly coupled together. A new configuration now suspends the cell as a pendulum on a string, with thermal contact made by copper wires. Piezo sensor measurements show this reduces the vibration reaching the refrigerator by two orders of magnitude, which should allow measurements at lower temperatures.

  19. Thickness-dependent metal-insulator transition in epitaxial SrRuO3 ultrathin films

    DOE PAGESBeta

    Shen, Xuan; Qiu, Xiangbiao; Su, Dong; Zhou, Shengqiang; Li, Aidong; Wu, Di

    2015-01-06

    Transport characteristics of ultrathin SrRuO₃ films, deposited epitaxially on TiO₂-terminated SrTiO₃ (001) single-crystal substrates, were studied as a function of film thickness. Evolution from a metallic to an insulating behavior is observed as the film thickness decreases from 20 to 4 unit cells. In films thicker than 4 unit cells, the transport behavior obeys the Drude low temperature conductivity with quantum corrections, which can be attributed to weak localization. Fitting the data with 2-dimensional localization model indicates that electron-phonon collisions are the main inelastic relaxation mechanism. In the film of 4 unit cells in thickness, the transport behavior follows variablemore » range hopping model, indicating a strongly localized state. As a result, magnetoresistance measurements reveal a likely magnetic anisotropy with the magnetic easy axis along the out-of-plane direction.« less

  20. Two-dimensional mapping of falling water film thickness with near-infrared attenuation

    NASA Astrophysics Data System (ADS)

    Dupont, J.; Mignot, G.; Prasser, H.-M.

    2015-05-01

    We have developed an optical technique for the two-dimensional mapping of water film thickness. The technique is based on infrared light absorption. A near-infrared camera is used to capture the radiation returning from a surface illuminated by a halogen lamp. The attenuation of the back-scattered radiation is used as a measure for the thickness of the water film covering the surface. The method was calibrated using well-defined liquid films between a glass plate and the surface. Series of instantaneous, two-dimensional thickness profiles of wavy turbulent free-falling films along a vertical wall were measured at a frame rate of 200 Hz. The evolution of complex flow patterns with three-dimensional instabilities such as long waves and capillary waves was observed under isothermal conditions. For the validation of the method, simultaneous independent measurements were taken together with an electrical high-speed liquid film sensor.

  1. A method for measuring the thickness of transparent oil film on water surface using laser trigonometry

    NASA Astrophysics Data System (ADS)

    Qieni, Lü; Baozhen, Ge; Wenda, Yao; Yimo, Zhang

    2011-01-01

    We present a method for measurement of thickness of transparent oil film on water surface based on laser trigonometry. With an oblique incident mode of single-point laser triangulation ranging system, laser light is incident on the upper and lower surfaces of the oil film being measured and an ellipse light spot is formed on the upper and lower surfaces of the oil film. The two light spots are imaged on an image plane CCD by an imaging lens and the image spot is formed and stored in a computer. The thickness of oil film being measured can be obtained by displacement of the image spot and the configuration parameter of the imaging system. The experiment is conducted using edible peanut oil and diesel oil. The research results show that the method presented in this paper is feasible and applicable to dynamic on-line measurement of oil film thickness of oil spill on sea surface.

  2. Structural, transport and microwave properties of 123/sapphire films: Thickness effect

    NASA Technical Reports Server (NTRS)

    Predtechensky, M. R.; Smal, A. N.; Varlamov, Yu. D.; Vatnik, S. M.; Tukhto, O. M.; Vasileva, I. G.

    1995-01-01

    The effect of thickness and growth conditions on the structure and microwave properties has been investigated for the 123/sapphire films. It has been shown that in the conditions of epitaxial growth the Al atoms do not diffuse from substrate into the film and the films with thickness up to 100 nm exhibit the excellent direct current (DC) properties. The increase of thickness of GdBaCuO films causes the formation of extended line-mesh defects and the increase of the surface resistance (R(sub S)). The low value of surface resistance R(sub S)(75 GHz, 77K) = 20 mOhm has been obtained for the two layer YBaCuO/CdBaCuO/sapphire films.

  3. Structural, transport and microwave properties of 123/sapphire films: Thickness effect

    SciTech Connect

    Predtechensky, MR.; Smal, A.N.; Varlamov, Y.D.

    1994-12-31

    The effect of thickness and growth conditions on the structure and microwave properties has been investigated for the 123/sapphire films. It has been shown that in the conditions of epitaxial growth and Al atoms do not diffuse from substrate into the film and the films with thickness up to 100nm exhibit the excellent DC properties. The increase of thickness of GdBaCuO films causes the formation of extended line-mesh defects and the increase of the surface resistance (R{sub S}). The low value of surface resistance R{sub S}(75GHz,77K)=20 mOhm has been obtained for the two layer YBaCuO/CdBaCuO/sapphire films.

  4. Quantitative study of GaAs nanowires catalyzed by Au film of different thicknesses

    PubMed Central

    2012-01-01

    In this letter, we quantitatively investigated epitaxial GaAs nanowires catalyzed by thin Au films of different thicknesses on GaAs (111)B substrates in a metal-organic chemical vapor deposition reactor. Prior to nanowire growth, the de-wetting of Au thin films to form Au nanoparticles on GaAs (111)B in AsH3 ambient at different temperatures is investigated. It is found that with increasing film thickness, the size of the Au nanoparticles increases while the density of the nanoparticles reduces. Furthermore, higher annealing temperature produces larger Au nanoparticles for a fixed film thickness. As expected, the diameters and densities of the as-grown GaAs nanowires catalyzed by these thin Au films reflect these trends. PMID:23095345

  5. Thickness dependence of the magnetic properties of ripple-patterned Fe/MgO(001) films

    NASA Astrophysics Data System (ADS)

    Büttner, Felix; Zhang, Kun; Seyffarth, Susanne; Liese, Tobias; Krebs, Hans-Ulrich; Vaz, C. A. F.; Hofsäss, Hans

    2011-08-01

    Grazing incidence Xe+ ion sputtering was used to create a nanoscale ripple pattern on a thin Fe film, epitaxially grown on MgO(001). The Fe film has a thickness gradient of 0-20 nm and a ripple height of about 3 nm, giving rise to a transition from a continuous film to separated nanorods with decreasing film thickness. This allowed the investigation of the competition between the uniaxial and biaxial anisotropy of the irradiated sample as a function of thickness. From magneto-optical Kerr effect measurements, we determine accurately the cubic magnetocrystalline anisotropy and the uniaxial anisotropy that originates from the ripple pattern using a coherent rotation model. Our results show that the uniaxial anisotropy strength increases, whereas the contribution of the biaxial crystal anisotropy decreases, when going from the continuous film to the nanorod structures.

  6. Highly Laminated Soft Magnetic Electroplated CoNiFe Thick Films

    SciTech Connect

    Kim, J; Kim, M; Herrault, F; Park, J; Allen, MG

    2013-01-01

    The fabrication and characterization of highly laminated (similar to 40 layers), thick (similar to 40 mu m) films of magnetically soft cobalt-nickel-iron are presented. Thick film fabrication is based on automated sequential electrodeposition of alternating CoNiFe and copper layers, followed by selective copper removal. The film, comprised tens of 1 mu m thick laminations, exhibits saturation flux density of 1.8 T and coercivity of approximately 1.3 Oe. High-frequency film characterization took place in a 36-turn test inductor, which demonstrated constant inductance of 1.6 mu H up to 10 MHz, indicating suppressed eddy-current loss. Quality factor exceeding 40 at 1 MHz, surpassing the performance of similarly fabricated Permalloy (Ni80Fe20) films.

  7. 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.

  8. Preliminary indications of water film distribution and thickness on an airfoil in a water spray

    NASA Technical Reports Server (NTRS)

    Hastings, E. C., Jr.; Weinstein, L. M.

    1984-01-01

    A sensor for measuring water film thickness is evaluated. The test is conducted in a small flow apparatus with a 1 ft chord model wing in a water spray. Photographic and visual observations are made of the upper wing surface and film thickness is measured on the upper and lower wing surfaces. The performance of the sensor appears highly satisfactory, and where valid comparisons can be made, repeatable results are obtained.

  9. Magneto-optical Kerr effect in NiZn ferrite films of variable thickness

    NASA Astrophysics Data System (ADS)

    Calle, C.; Calle, V. H.; Cuéllar, F.; Cortés, A.; Arias, D.; Lopera, W.; Prieto, P.; Guzmán, O.; Mendoza, G. A.

    2006-10-01

    NiZn ferrites films deposited by RF sputtering technique on (1 0 0)-Si substrates have been studied by the magneto-optical Kerr effect. The coercivity behavior as a function of the thickness indicates a spin reversal mainly governed by the single domain regime. The Jiles-Atherton Model was used to fit the experimental hysteresis loop. The k pinning parameter of the model increases by increasing film thicknesses

  10. Thickness Effect on Properties of Sprayed In2S3 Films for Photovoltaic Applications

    NASA Astrophysics Data System (ADS)

    Bouguila, N.; Kraini, M.; Halidou, I.; Lacaze, E.; Bouchriha, H.; Bouzouita, H.

    2016-01-01

    Indium sulfide (In2S3) films have been deposited on soda-lime glass substrates using a spray technique (CSP). Indium chloride and thiourea were used as precursors at a molar ratio of S:In = 2. The substrate temperature was fixed at 340°C. The effect of film thickness on the structural, morphological and optical properties of the as-deposited films has been studied. These films were characterized by x-ray diffraction, scanning electron microscopy (SEM), atomic force microscopy (AFM) and optical absorption spectroscopy. As-prepared samples were polycrystalline with a cubic structure and (400) as preferential orientation. Their grain size increased from 35 nm to 41 nm with increasing thickness whereas the dislocation density and microstrain of the films decreased with the increase of thickness. Both SEM and AFM images showed that the films were homogenous with an increase of the surface roughness with the increase of thickness. The optical transmittance of the films decreased from 80% to 20% in the visible and infrared regions when the thickness was increased from 0.78 μm to 6.09 μm. The optical band gap E g was found to be in the range of 2.75-2.19 eV and showed a decrease with film thickness. Based on the measured optical constants (n and k), a Wemple-Didomenico model was used to determine the values of single oscillator energy ( E 0), dispersion energy ( E d), optical band gap ( E g) and high frequency dielectric constant ( \\varepsilon_{∞} ). In addition, these films exhibited n-type conductivity and were highly resistive. These results confirm that In2S3 thin films are a promising alternative as a buffer-layer material for CuInGa(S,Se)2-based solar cells.

  11. Temperature- and thickness-dependent elastic moduli of polymer thin films.

    PubMed

    Ao, Zhimin; Li, Sean

    2011-01-01

    The mechanical properties of polymer ultrathin films are usually different from those of their counterparts in bulk. Understanding the effect of thickness on the mechanical properties of these films is crucial for their applications. However, it is a great challenge to measure their elastic modulus experimentally with in situ heating. In this study, a thermodynamic model for temperature- (T) and thickness (h)-dependent elastic moduli of polymer thin films Ef(T,h) is developed with verification by the reported experimental data on polystyrene (PS) thin films. For the PS thin films on a passivated substrate, Ef(T,h) decreases with the decreasing film thickness, when h is less than 60 nm at ambient temperature. However, the onset thickness (h*), at which thickness Ef(T,h) deviates from the bulk value, can be modulated by T. h* becomes larger at higher T because of the depression of the quenching depth, which determines the thickness of the surface layer δ. PMID:21711747

  12. Thickness and microstructure effects in the optical and electrical properties of silver thin films

    SciTech Connect

    Ding, Guowen Clavero, César; Schweigert, Daniel; Le, Minh

    2015-11-15

    The optical and electrical response of metal thin films approaching thicknesses in the range of the electron mean free path is highly affected by electronic scattering with the interfaces and defects. Here, we present a theoretical and experimental study on how thickness and microstructure affect the properties of Ag thin films. We are able to successfully model the electrical resistivity and IR optical response using a thickness dependent electronic scattering time. Remarkably, the product of electronic scattering time and resistivity remains constant regardless of the thickness (τx ρ = C), with a value of 59 ± 2 μΩ cm ⋅ fs for Ag films in the investigated range from 3 to 74 nm. Our findings enable us to develop a theoretically framework that allows calculating the optical response of metal thin films in the IR by using their measured thickness and resistivity. An excellent agreement is found between experimental measurements and predicted values. This study also shows the theoretical lower limit for emissivity in Ag thin films according to their microstructure and thickness. Application of the model presented here will allow rapid characterization of the IR optical response of metal thin films, with important application in a broad spectrum of fundamental and industrial applications, including optical coatings, low-emissivity windows and semiconductor industry.

  13. Temperature- and thickness-dependent elastic moduli of polymer thin films

    PubMed Central

    2011-01-01

    The mechanical properties of polymer ultrathin films are usually different from those of their counterparts in bulk. Understanding the effect of thickness on the mechanical properties of these films is crucial for their applications. However, it is a great challenge to measure their elastic modulus experimentally with in situ heating. In this study, a thermodynamic model for temperature- (T) and thickness (h)-dependent elastic moduli of polymer thin films Ef(T,h) is developed with verification by the reported experimental data on polystyrene (PS) thin films. For the PS thin films on a passivated substrate, Ef(T,h) decreases with the decreasing film thickness, when h is less than 60 nm at ambient temperature. However, the onset thickness (h*), at which thickness Ef(T,h) deviates from the bulk value, can be modulated by T. h* becomes larger at higher T because of the depression of the quenching depth, which determines the thickness of the surface layer δ. PMID:21711747

  14. Film thickness measurement techniques applied to micro-scale two-phase flow systems

    SciTech Connect

    Tibirica, Cristiano Bigonha; do Nascimento, Francisco Julio; Ribatski, Gherhardt

    2010-05-15

    Recently semi-empirical models to estimate flow boiling heat transfer coefficient, saturated CHF and pressure drop in micro-scale channels have been proposed. Most of the models were developed based on elongated bubbles and annular flows in the view of the fact that these flow patterns are predominant in smaller channels. In these models, the liquid film thickness plays an important role and such a fact emphasizes that the accurate measurement of the liquid film thickness is a key point to validate them. On the other hand, several techniques have been successfully applied to measure liquid film thicknesses during condensation and evaporation under macro-scale conditions. However, although this subject has been targeted by several leading laboratories around the world, it seems that there is no conclusive result describing a successful technique capable of measuring dynamic liquid film thickness during evaporation inside micro-scale round channels. This work presents a comprehensive literature review of the methods used to measure liquid film thickness in macro- and micro-scale systems. The methods are described and the main difficulties related to their use in micro-scale systems are identified. Based on this discussion, the most promising methods to measure dynamic liquid film thickness in micro-scale channels are identified. (author)

  15. The effect of Argon ion irradiation on the thickness and structure of ultrathin amorphous carbon films

    NASA Astrophysics Data System (ADS)

    Xie, J.; Komvopoulos, K.

    2016-03-01

    Carbon films synthesized by plasma-enhanced chemical vapor deposition (PECVD) and filtered cathodic vacuum arc (FCVA) exhibit a layered structure consisting of a bottom (interface) and a top (surface) layer rich in sp2 atomic carbon bonding and a middle (bulk) layer of much higher sp3 content. Because of significant differences in the composition, structure, and thickness of these layers, decreasing the film thickness may negatively affect its properties. In this study, transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) were used to examine the effect of Ar+ ion irradiation on the structure and thickness of ultrathin films of hydrogenated amorphous carbon (a-C:H) and hydrogen-free amorphous carbon (a-C) deposited by PECVD and FCVA, respectively. The TEM and EELS results show that 2-min ion irradiation decreases the film thickness without markedly changing the film structure and composition, whereas 4-min ion irradiation results in significant film thinning and a moderate decrease of the sp3 content of the bulk layer. This study demonstrates that Ar+ ion irradiation is an effective post-deposition process for reducing the thickness and tuning the structure of ultrathin carbon films. This capability has direct implications in the synthesis of ultrathin protective carbon overcoats for extremely high-density magnetic recording applications.

  16. Fabrication and characterization of piezoelectric micromachined ultrasonic transducers with thick composite PZT films.

    PubMed

    Wang, Zhihong; Zhu, Weiguang; Zhu, Hong; Miao, Jianmin; Chao, Chen; Zhao, Changlei; Tan, Ooi Kiang

    2005-12-01

    Ferroelectric microelectromechanical systems (MEMS) has been a growing area of research in past decades, in which ferroelectric films are combined with silicon technology for a variety of applications, such as piezo-electric micromachined ultrasonic transducers (pMUTs), which represent a new approach to ultrasound detection and generation. For ultrasound-radiating applications, thicker PZT films are preferred because generative force and response speed of the diaphragm-type transducers increase with increasing film thickness. However, integration of 4- to 20-microm thick PZT films on silicon wafer, either the deposition or the patterning, is still a bottleneck in the micromachining process. This paper reports on a diaphragm-type pMUT. A composite coating technique based on chemical solution deposition and high-energy ball milled powder has been used to fabricate thick PZT films. Micromachining of the pMUTs using such thick films has been investigated. The fabricated pMUT with crack-free PZT films up to 7-microm thick was evaluated as an ultrasonic transmitter. The generated sound pressure level of up to 120 dB indicates that the fabricated pMUT has very good ultrasound-radiating performance and, therefore, can be used to compose pMUT arrays for generating ultrasound beam with high directivity in numerous applications. The pMUT arrays also have been demonstrated. PMID:16463494

  17. The effect of film thickness on critical properties of YBCO film fabricated by TFA-MOD using 211-process

    NASA Astrophysics Data System (ADS)

    Lim, J. H.; Jang, S. H.; Kim, K. T.; Hwang, S. M.; Joo, J.; Lee, H.-J.; Lee, H.-G.; Hong, G.-W.

    2007-10-01

    YBCO films were fabricated by the TFA-MOD method using the "211-process", and the effects of the film thickness on phase formation, microstructure, texture evolution, and critical properties were evaluated. Various film thicknesses ranging from 0.41 μm to 2.14 μm were obtained by repeating the dip coating and calcining processes one to five times. The critical properties varied significantly with the film thickness. The Ic increased from 35 to 105 A/cm-width with increasing the film thickness from 0.41 μm to 1.17 μm. On the other hand, the corresponding Jc remained almost constant in the range of 0.76-0.90 MA/cm2. With further increases in thickness, these values decreased drastically, which was attributed to the degraded microstructure, i.e., the formation of BaF2 and a-axis grains and degraded texture and surface morphology arising from the insufficient heat treatment time. It is believed that the optimum thickness for improving both the Ic and Jc values is approximately 1.17 μm.

  18. Planar Zeolite Film-Based Potentiometric Gas Sensors Manufactured by a Combined Thick-Film and Electroplating Technique

    PubMed Central

    Marr, Isabella; Reiß, Sebastian; Hagen, Gunter; Moos, Ralf

    2011-01-01

    Zeolites are promising materials in the field of gas sensors. In this technology-oriented paper, a planar setup for potentiometric hydrocarbon and hydrogen gas sensors using zeolites as ionic sodium conductors is presented, in which the Pt-loaded Na-ZSM-5 zeolite is applied using a thick-film technique between two interdigitated gold electrodes and one of them is selectively covered for the first time by an electroplated chromium oxide film. The influence of the sensor temperature, the type of hydrocarbons, the zeolite film thickness, and the chromium oxide film thickness is investigated. The influence of the zeolite on the sensor response is briefly discussed in the light of studies dealing with zeolites as selectivity-enhancing cover layers. PMID:22164042

  19. Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT

    PubMed Central

    dos Santos, Valentin Aranha; Schmetterer, Leopold; Triggs, Graham J.; Leitgeb, Rainer A.; Gröschl, Martin; Messner, Alina; Schmidl, Doreen; Garhofer, Gerhard; Aschinger, Gerold; Werkmeister, René M.

    2016-01-01

    In optical coherence tomography (OCT), the axial resolution is directly linked to the coherence length of the employed light source. It is currently unclear if OCT allows measuring thicknesses below its axial resolution value. To investigate spectral-domain OCT imaging in the super-resolution regime, we derived a signal model and compared it with the experiment. Several island thin film samples of known refractive indices and thicknesses in the range 46 – 163 nm were fabricated and imaged. Reference thickness measurements were performed using a commercial atomic force microscope. In vivo measurements of the tear film were performed in 4 healthy subjects. Our results show that quantitative super-resolved thickness measurement can be performed using OCT. In addition, we report repeatable tear film lipid layer visualization. Our results provide a novel interpretation of the OCT axial resolution limit and open a perspective to deeper extraction of the information hidden in the coherence volume. PMID:27446696

  20. Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT.

    PubMed

    Dos Santos, Valentin Aranha; Schmetterer, Leopold; Triggs, Graham J; Leitgeb, Rainer A; Gröschl, Martin; Messner, Alina; Schmidl, Doreen; Garhofer, Gerhard; Aschinger, Gerold; Werkmeister, René M

    2016-07-01

    In optical coherence tomography (OCT), the axial resolution is directly linked to the coherence length of the employed light source. It is currently unclear if OCT allows measuring thicknesses below its axial resolution value. To investigate spectral-domain OCT imaging in the super-resolution regime, we derived a signal model and compared it with the experiment. Several island thin film samples of known refractive indices and thicknesses in the range 46 - 163 nm were fabricated and imaged. Reference thickness measurements were performed using a commercial atomic force microscope. In vivo measurements of the tear film were performed in 4 healthy subjects. Our results show that quantitative super-resolved thickness measurement can be performed using OCT. In addition, we report repeatable tear film lipid layer visualization. Our results provide a novel interpretation of the OCT axial resolution limit and open a perspective to deeper extraction of the information hidden in the coherence volume. PMID:27446696

  1. Thick, low-stress films, and coated substrates formed therefrom, and methods for making same

    DOEpatents

    Henager, Jr., Charles H.; Knoll, Robert W.

    1992-01-01

    Stress-induced deformation, and the damage resulting therefrom, increases with film thickness. The overcoming of excessive stress by the use of the Si-Al-N film material of the present invention, permits the formation of thick films that are necessary for certain of the above described applications. The most likely use for the subject film materials, other than their specialized views as an optical film, is for microelectronic packaging of components on silicon substrates. In general, the subject films have excellent adherence to the underlying substrate, a high degree of hardness and durability, and are excellent insulators. Prior art elevated temperature deposition processes cannot meet the microelectronic packaging temperature formation constraints. The process of the present invention is conducted under non-elevated temperature conditions, typically 500.degree. C. or less.

  2. Thickness dependent wetting properties and surface free energy of HfO2 thin films

    NASA Astrophysics Data System (ADS)

    Zenkin, Sergei; Belosludtsev, Alexandr; Kos, Šimon; Čerstvý, Radomír; Haviar, Stanislav; Netrvalová, Marie

    2016-06-01

    We show here that intrinsic hydrophobicity of HfO2 thin films can be easily tuned by the variation of film thickness. We used the reactive high-power impulse magnetron sputtering for preparation of high-quality HfO2 films with smooth topography and well-controlled thickness. Results show a strong dependence of wetting properties on the thickness of the film in the range of 50-250 nm due to the dominance of the electrostatic Lifshitz-van der Waals component of the surface free energy. We have found the water droplet contact angle ranging from ≈120° for the thickness of 50 nm to ≈100° for the thickness of 2300 nm. At the same time the surface free energy grows from ≈25 mJ/m2 for the thickness of 50 nm to ≈33 mJ/m2 for the thickness of 2300 nm. We propose two explanations for the observed thickness dependence of the wetting properties: influence of the non-dominant texture and/or non-monotonic size dependence of the particle surface energy.

  3. Commercialization of a thick-film solar cell

    NASA Astrophysics Data System (ADS)

    McDonald, G. D.

    1980-12-01

    The use of screen printing as a technique for producing large area solar cells was evaluated with emphasis on the preparation and improvement in performance of screen printed CdS cells. Thermal gravimetric analysis of the CdS inks used to print CdS films confirm that all the fugitive binders and flux are removed under firing conditions used to prepare the CdS films. Warpage of the Nesatron glass substrates makes their use questionable. Multiple layers of CdS appear to resolve a pin hole problem previously encountered.

  4. Texture change through film thickness and off-axis accommodation of (0 0 2) planes

    NASA Astrophysics Data System (ADS)

    Shetty, A. R.; Karimi, A.

    2011-12-01

    We present our recent experimental results on the formation of off-axis texture and crystallographic tilting of crystallites that take place in thin film of transition metal nitrides. For this purpose, the microstructural development of TiAlN film was studied, specially the change in texture with film thickness. Fiber texture was measured using θ-2θ and pole figure X-ray diffraction (XRD), while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the microstructure and changes in texture with thickness. The sin2ψ method was applied to determine the stresses on (1 1 1) and (0 0 2) plane. With deposition parameters chosen, the growth texture mechanism is discussed in three different stages of film growth. Surface energy minimization at low thickness leads to the development of (0 0 2) orientation. On the other hand, the competitive growth promotes the growth of (1 1 1) planes parallel to film surface at higher thickness. However, contrary to the prediction of growth models, the (0 0 2) grains are not completely overlapped by (1 1 1) grains at higher thickness. Rather the (0 0 2) grains still constitute the surface, but are tilted away from the substrate normal showing substantial in-plane alignment to allow the (1 1 1) planes remain parallel to film surface. Intrinsic stress along (1 1 1) and (0 0 2) shows a strong dependence with preferred orientation. The stress level in (0 0 2) grains which was compressive at low thickness changes to tensile at higher thickness. This change in the nature of stress allows the (0 0 2) planes to tilt away in order to promote the growth of <1 1 1> parallel to film normal and to minimize the overall energy of system due to high compressive stress stored in the (1 1 1) grains. The change in surface morphology with thickness was observed using SEM. An increase in surface roughness with film thickness was observed which indicates the development of (1 1 1) texture parallel to film surface

  5. New diffusive gradients in a thin film technique for measuring inorganic arsenic and selenium(IV) using a titanium dioxide based adsorbent.

    PubMed

    Bennett, William W; Teasdale, Peter R; Panther, Jared G; Welsh, David T; Jolley, Dianne F

    2010-09-01

    A new diffusive gradients in a thin film (DGT) technique, using a titanium dioxide based adsorbent (Metsorb), has been developed and evaluated for the determination of dissolved inorganic arsenic and selenium. As(III), As(V), and Se(IV) were found to be quantitatively accumulated by the adsorbent (uptake efficiencies of 96.5-100%) and eluted in 1 M NaOH (elution efficiencies of 81.2%, 75.2%, and 88.7%). Se(VI) was not quantitatively accumulated by the adsorbent (<20%). Laboratory DGT validation experiments gave linear mass uptake over time (R(2) >or= 0.998) for As(III), As(V), and Se(IV). Consistent uptake occurred over pH (3.5-8.5) and ionic strength (0.0001-0.75 mol L(-1) NaNO(3)) ranges typical of natural waters, including seawater. Field deployments of DGT probes with various diffusive layer thicknesses confirmed the use of the technique in situ, allowing calculation of the diffusive boundary layers and an accurate measurement of inorganic arsenic. Reproducibility of the technique in field deployments was good (relative standard deviation <8%). Limits of detection (4 day deployments) were 0.01 microg L(-1) for inorganic arsenic and 0.05 microg L(-1) for Se(IV). The results of this study confirmed that DGT with Metsorb was a reliable and robust method for the measurement of inorganic arsenic and the selective measurement of Se(IV) within useful limits of accuracy. PMID:20695441

  6. Relationships between processing temperature and microstructure in isothermal melt processed Bi-2212 thick films

    SciTech Connect

    Holesinger, T.G.; Phillips, D.S.; Willis, J.O.; Peterson, D.E.

    1995-05-01

    The microstructure and phase assemblage of isothermal melt processed (IMP) Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (Bi-2212) thick films have been evaluated. Results from compositional analysis and phase identification indicate that the characteristics of the partial melt greatly influence the microstructural and chemical development of the thick films. The highest critical current densities were obtained in films processed below 800{degrees}C where the partial melt uniformly coats the substrate without excessive phase segregation.

  7. Resistive switching in a few nanometers thick tantalum oxide film formed by a metal oxidation

    SciTech Connect

    Ohno, Takeo; Samukawa, Seiji

    2015-04-27

    Resistive switching in a Cu/Ta{sub 2}O{sub 5}/Pt structure that consisted of a few nanometer-thick Ta{sub 2}O{sub 5} film was demonstrated. The Ta{sub 2}O{sub 5} film with thicknesses of 2–5 nm was formed with a combination of Ta metal film deposition and neutral oxygen particle irradiation at room temperature. The device exhibited a bipolar resistive switching with a threshold voltage of 0.2 V and multilevel switching operation.

  8. Tuning thermoelectricity in a Bi2Se3 topological insulator via varied film thickness

    NASA Astrophysics Data System (ADS)

    Guo, Minghua; Wang, Zhenyu; Xu, Yong; Huang, Huaqing; Zang, Yunyi; Liu, Chang; Duan, Wenhui; Gan, Zhongxue; Zhang, Shou-Cheng; He, Ke; Ma, Xucun; Xue, Qikun; Wang, Yayu

    2016-01-01

    We report thermoelectric transport studies on Bi2Se3 topological insulator thin films with varied thickness grown by molecular beam epitaxy. We find that the Seebeck coefficient and thermoelectric power factor decrease systematically with the reduction of film thickness. These experimental observations can be explained quantitatively by theoretical calculations based on realistic electronic band structure of the Bi2Se3 thin films. This work illustrates the crucial role played by the topological surface states on the thermoelectric transport of topological insulators, and sheds new light on further improvement of their thermoelectric performance.

  9. Terahertz paintmeter for noncontact monitoring of thickness and drying progress in paint film

    NASA Astrophysics Data System (ADS)

    Yasui, Takeshi; Yasuda, Takashi; Sawanaka, Ken-Ichi; Araki, Tsutomu

    2005-11-01

    We propose a paintmeter for noncontact and remote monitoring of the thickness and drying progress of a paint film based on the time-of-flight measurement of the echo signal of a terahertz (THz) electromagnetic pulse. The proposed method is effectively applied to two-dimensional mapping of the painting thickness distribution for single-layer and multilayer paint films. Furthermore, adequate parameters for the drying progress are extracted from the THz pulse-echo signal and effectively applied to monitor the wet-to-dry transformation. The THz paintmeter can be a powerful tool for quality control of the paint film on the in-process monitoring of car body painting.

  10. Tuning thermoelectricity in a Bi2Se3 topological insulator via varied film thickness

    DOE PAGESBeta

    Guo, Minghua; Wang, Zhenyu; Xu, Yong; Huang, Huaqing; Zang, Yunyi; Liu, Chang; Duan, Wenhui; Gan, Zhongxue; Zhang, Shou-Cheng; He, Ke; et al

    2016-01-12

    We report thermoelectric transport studies on Bi2Se3 topological insulator thin films with varied thickness grown by molecular beam epitaxy. We find that the Seebeck coefficient and thermoelectric power factor decrease systematically with the reduction of film thickness. These experimental observations can be explained quantitatively by theoretical calculations based on realistic electronic band structure of the Bi2Se3 thin films. Lastly, this work illustrates the crucial role played by the topological surface states on the thermoelectric transport of topological insulators, and sheds new light on further improvement of their thermoelectric performance.

  11. Optimizing diode thickness for thin-film solid state thermal neutron detectors

    SciTech Connect

    Murphy, John W.; Mejia, Israel; Quevedo-Lopez, Manuel A.; Gnade, Bruce; Kunnen, George R.; Allee, David

    2012-10-01

    In this work, we investigate the optimal thickness of a semiconductor diode for thin-film solid state thermal neutron detectors. We evaluate several diode materials, Si, CdTe, GaAs, C (diamond), and ZnO, and two neutron converter materials, {sup 10}B and {sup 6}LiF. Investigating a coplanar diode/converter geometry, we determine the minimum semiconductor thickness needed to achieve maximum neutron detection efficiency. By keeping the semiconductor thickness to a minimum, gamma rejection is kept as high as possible. In this way, we optimize detector performance for different thin-film semiconductor materials.

  12. Optical spectroscopy of sputtered nanometer-thick yttrium iron garnet films

    SciTech Connect

    Jakubisova-Liskova, Eva Visnovsky, Stefan; Chang, Houchen; Wu, Mingzhong

    2015-05-07

    Nanometer (nm)-thick yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}, YIG) films present interest for spintronics. This work employs spectral ellipsometry and magneto-optic Kerr effect (MOKE) spectra to characterize nm-thick YIG films grown on single-crystal Gd{sub 3}Ga{sub 5}O{sub 12} substrates by magnetron sputtering. The thickness (t) of the films ranges between 10 nm and 40 nm. Independent on t, the polar MOKE hysteresis loops saturate in the field of about 1.8 kOe, consistent with the saturation magnetization in bulk YIG (4πM{sub s} ≈ 1.75 kG). The MOKE spectrum measured at photon energies between 1.3 eV and 4.5 eV on the 38-nm-thick film agrees with that measured on single-crystal YIG bulk materials. The MOKE spectrum of the 12-nm-thick film still preserves the structure of the bulk YIG but its amplitude at lower photon energies is modified due to the fact that the radiation penetration depth exceeds 20 nm. The t dependence of the MOKE amplitude is consistent with MOKE calculations. The results indicate that the films are stoichiometric, strain free, without Fe{sup 2+}, and preserve bulk YIG properties down to t ≈ 10 nm.

  13. Thickness and UV irradiation effects on the gas sensing properties of Te thin films

    SciTech Connect

    Manouchehrian, M.; Larijani, M.M.; Elahi, S.M.

    2015-02-15

    Highlights: • Tellurium thin films were prepared by thermal evaporation technique. • Tellurium thin films showed excellent gas-sensing properties to H{sub 2}S at room temperature. • Tellurium showed a remarkably enhanced response to H{sub 2}S gas under UV irradiation. • The reason of the enhanced response by UV irradiation was discussed. - Abstract: In this research, tellurium thin films were investigated for use as hydrogen sulfide gas sensors. To this end, a tellurium thin film has been deposited on Al{sub 2}O{sub 3} substrates by thermal evaporation, and the influence of thickness on the sensitivity of the tellurium thin film for measuring H{sub 2}S gas is studied. XRD patterns indicate that as the thickness increases, the crystallization improves. Observing the images obtained by SEM, it is seen that the grain size increases as the thickness increases. Studying the effect of thickness on H{sub 2}S gas measurement, it became obvious that as the thickness increases, the sensitivity decreases and the response and recovery times increase. To improve the response and recovery times of the tellurium thin film for measuring H{sub 2}S gas, the influence of UV radiation while measuring H{sub 2}S gas was also investigated. The results indicate that the response and recovery times strongly decrease using UV radiation.

  14. Cylinder wakes in quasi-two-dimensional flows with surface friction II: effects of film thickness

    NASA Astrophysics Data System (ADS)

    Li, Jamie H. W.; Shim, Jemin; Fontana, Paul W.

    2013-11-01

    Vortex shedding in a quasi-two-dimensional system with homogeneous drag (Ekman friction) is observed to have different phenomenology than in systems without friction. To understand why, we studied the wakes of circular cylinders in a vertical soap film channel and measured thickness profiles (pachymetry) of the film in the cylinder wake. The kinematic viscosity and drag coefficients in this system both depend on the thickness of the soap film, which varies over the wake. To measure thickness, broad-spectrum light is reflected off the film, and the resulting interference pattern of intensity vs. wave number is measured. The spacing in wave number of the interference minima is proportional to the film thickness, giving high-accuracy thickness measurements with a precision on the order of 0.2%. Pachymetry profiles transverse to the mean flow were measured at five longitudinal positions for various values of Reynolds number and drag parameter. Possible causes for differences in the dynamics from conventional systems could be: ambiguity in the specifications of Reynolds number or non-Newtonian effects arising from viscosity gradients, elastic effects particular to soap films, or surface friction. The pachymetry results favor the latter explanation. Supported by the National Science Foundation under Grant No. CBET-0854509, the M. J. Murdock Charitable Trust, and the Clare Boothe Luce Foundation.

  15. Ceramic thick film humidity sensor based on MgTiO{sub 3} + LiF

    SciTech Connect

    Kassas, Ahmad; Bernard, Jérôme; Lelièvre, Céline; Besq, Anthony; Guhel, Yannick; Houivet, David; Boudart, Bertrand; Lakiss, Hassan; Hamieh, Tayssir

    2013-10-15

    Graphical abstract: - Highlights: • The fabricated sensor based on MgTiO{sub 3} + LiF materials used the spin coating technology. • The response time is 70 s to detect variation between 5 and 95% relative humidity. • The addition of Scleroglucan controls the viscosity and decreases the roughness of thick film surface. • This humidity sensor is a promising, low-cost, high-quality, reliable ceramic films, that is highly sensitive to humidity. - Abstract: The feasibility of humidity sensor, consisting of a thick layer of MgTiO{sub 3}/LiF materials on alumina substrate, was studied. The thermal analysis TGA-DTGA and dilatometric analysis worked out to confirm the sintering temperature. An experimental plan was applied to describe the effects of different parameters in the development of the thick film sensor. Structural and microstructural characterizations of the developed thick film were made. Rheological study with different amounts of a thickener (scleroglucan “sclg”), showing the behavior variation, as a function of sclg weight % was illustrated and rapprochement with the results of thickness variation as a function of angular velocity applied in the spin coater. The electrical and dielectric measurements confirmed the sensitivity of the elaborated thick film against moisture, along with low response time.

  16. Thickness dependent fatigue life at microcrack nucleation for metal thin films on flexible substrates

    NASA Astrophysics Data System (ADS)

    Sun, X. J.; Wang, C. C.; Zhang, J.; Liu, G.; Zhang, G. J.; Ding, X. D.; Zhang, G. P.; Sun, J.

    2008-10-01

    For polymer-supported metal thin films used in flexible electronics, the definition of the fatigue lifetime at microcrack nucleation (FLMN) should be more physically meaningful than all the previous definitions at structural instability. In this paper, the FLMN of Cu films (with thickness from 100 nm to 3.75 µm) as well as Al thin films (from 80 to 800 nm) was experimentally characterized at different strain ranges and different thicknesses by using a simple electrical resistance measurement (ERM). A significant thickness dependence was revealed for the FLMN and a similar Coffin-Manson fatigue relationship observed commonly in bulk materials was found to be still operative in both the films. Microstructural analyses were carried out to verify the feasibility of ERM correspondingly.

  17. Thick Pb(Zr,Ti)O{sub 3} film without substrate

    SciTech Connect

    Lee, Jae-Wung; Park, Chee-Sung; Jo, Ji-Hoon; Kim, Hyoun-Ee

    2007-08-13

    In order to fabricate thick PbZr{sub x}Ti{sub 1-x}O{sub 3} (PZT) films for microelectromechanical system applications, the authors introduce a concept of freestanding film without a substrate. PZT films with a thickness of up to 20 {mu}m were deposited on a very thin Pt layer without a substrate by the rf-magnetron sputtering method using a single oxide target. The Pt layer (thickness <1 {mu}m) was obtained by sputtering the Pt on a Si substrate with a carbon layer between them, and subsequently removing the carbon layer by oxidation in air at 400 deg. C. Piezoelectric properties of the film were comparable to those of bulk PZT as a result of the removal of clamping effect of the substrate.

  18. Thin films' thickness uniformity associated with the method of electron beam evaporation

    NASA Astrophysics Data System (ADS)

    Xia, Zhilin; Xue, Yiyu; Guo, Peitao; Li, Zhangwang

    2009-08-01

    Coating material has been considered as being made up of a lot of small tablets. These tablets have plane surface during the whole film preparation process. Based on the assumption that a column etching pit will form in coating material when electron beam is used for heating, influences of the etching pit's dimension and the internal structure of the vacuum chamber on films thickness uniformity have been investigated. Results reflect that the appearance of etching pit does not always cause negative influence on films thickness uniformity. The negative impact of etching on films thickness uniformity can be reduced by optimizing the internal structure of the vacuum chamber and preparation technical parameters. But, it is difficult to achieve the beneficial action. This investigation is useful to help us understand physical meaning of the emission characteristics of the evaporation particle and design experimental scheme.

  19. Growth of BaTiO3-PVDF composite thick films by using aerosol deposition

    NASA Astrophysics Data System (ADS)

    Cho, Sung Hwan; Yoon, Young Joon

    2016-01-01

    Barium titanate (BaTiO3)-polyvinylidene fluoride (PVDF) composite thick films were grown by using aerosol deposition at room temperature with BaTiO3 and PVDF powders. To produce a uniform composition in ceramic and polymer composite films, which show a substantial difference in specific gravity, we used PVDF-coated BaTiO3 powders as the starting materials. An examination of the microstructure confirmed that the BaTiO3 were well distributed in the PVDF matrix in the form of a 0 - 3 compound. The crystallite size in the BaTiO3-PVDF composite thick films was 5 ˜ 50 times higher than that in pure BaTiO3 thick films. PVDF plays a role in suppressing the fragmentation of BaTiO3 powder during the aerosol deposition process and in controlling the relative permittivity.

  20. Interference method for monitoring the refractive index and the thickness of transparent films during deposition

    NASA Astrophysics Data System (ADS)

    Alius, H.; Schmidt, R.

    1990-04-01

    An interferometric method is described for simultaneous measurement of the refractive index and the thickness of transparent isotropic films during the deposition process. Two laser beams are focused impinging at two different angles onto the film. The intensity of the beams reflected from the growing film shows minima and maxima, which are counted and evaluated to determine the refractive index n and the thickness d of the film in the range of some 100 nm up to several micrometers using 633-nm laser light. n and d can be determined within an accuracy better than 1%, if the thickness is larger than three times the vacuum wavelength of the laser. The measurements are well in accordance with calculations of the intensity modulation. The method can easily be extended to multilayer systems.

  1. Self-Poling of BiFeO3 Thick Films.

    PubMed

    Khomyakova, Evgeniya; Sadl, Matej; Ursic, Hana; Daniels, John; Malic, Barbara; Bencan, Andreja; Damjanovic, Dragan; Rojac, Tadej

    2016-08-01

    Bismuth ferrite (BiFeO3) is difficult to pole because of the combination of its high coercive field and high electrical conductivity. This problem is particularly pronounced in thick films. The poling, however, must be performed to achieve a large macroscopic piezoelectric response. This study presents evidence of a prominent and reproducible self-poling effect in few-tens-of-micrometer-thick BiFeO3 films. Direct and converse piezoelectric measurements confirmed that the as-sintered BiFeO3 thick films yield d33 values of up to ∼20 pC/N. It was observed that a significant self-poling effect only appears in cases when the films are heated and cooled through the ferroelectric-paraelectric phase transition (Curie temperature TC ∼ 820 °C). These self-poled films exhibit a microstructure with randomly oriented columnar grains. The presence of a compressive strain gradient across the film thickness cooled from above the TC was experimentally confirmed and is suggested to be responsible for the self-poling effect. Finally, the macroscopic d33 response of the self-poled BiFeO3 film was characterized as a function of the driving-field frequency and amplitude. PMID:27388568

  2. Thickness-dependent autophobic dewetting of thin polymer films on coated substrates.

    PubMed

    Sun, Yan; Shull, Kenneth R; Walko, Donald A; Wang, Jin

    2011-01-01

    We demonstrate that the wetting behavior of a thin liquid film, poly(4-bromostyrene) (PBrS), on top of a solid substrate may be effectively controlled with the insertion of a secondary liquid film, poly(4-vinyl pyridine) (P4VP), underneath the primary film. This secondary film remains stable under all conditions, and can be viewed as an extension of the substrate itself. On the basis of results from X-ray standing waves generated via total external reflection from an X-ray mirror, time-of-flight secondary ion mass spectroscopy, optical microscopy, and atomic force microscopy, we construct the full Helmholtz free energy versus PBrS thickness curve using existing theories that account for both long- and short-range interactions. The form of the free energy curve, which contains an inflection point and an absolute minimum at a nonzero PBrS thickness, accurately reflects our observation that thick PBrS films undergo autophobic dewetting on top of the stable P4VP, while sufficiently thin PBrS films remain stable. The thickness of the autophobic wetting layer is controlled by the range of the repulsive interaction between the film and the substrate, and is found to be ∼4 nm for the PBrS/P4VP interface. PMID:21117671

  3. Superconducting properties and chemical composition of NbTiN thin films with different thickness

    SciTech Connect

    Zhang, L.; Peng, W.; You, L. X.; Wang, Z.

    2015-09-21

    In this research, we systematically investigated the superconducting properties and chemical composition of NbTiN thin films prepared on single-crystal MgO substrates. The NbTiN thin films with different thicknesses (4–100 nm) were deposited by reactive DC magnetron sputtering at ambient temperature. We measured and analyzed the crystal structure and thickness dependence of the chemical composition using X-ray diffraction and X-ray photoelectron spectroscopy depth profiles. The films exhibited excellent superconducting properties, with a high superconducting critical temperature of 10.1 K, low resistivity (ρ{sub 20} = 93 μΩ cm), and residual resistivity ratio of 1.12 achieved for 4-nm-thick ultrathin NbTiN films prepared at the deposition current of 2.4 A. The stoichiometry and electrical properties of the films varied gradually between the initial and upper layers. A minimum ρ{sub 20} of 78 μΩ cm and a maximum residual resistivity ratio of 1.15 were observed for 12-nm-thick films, which significantly differ from the properties of NbN films with the same NaCl structure.

  4. The ideal split-thickness skin graft donor site dressing: rediscovery of polyurethane film.

    PubMed

    Dornseifer, Ulf; Fichter, Andreas M; Herter, Frank; Sturtz, Gustavo; Ninkovic, Milomir

    2009-08-01

    The almost single disadvantage of polyurethane film dressings, an uncontrolled leakage, is probably as often described as its numerous advantages for split-thickness skin graft donor sites. We solved this problem by perforating the polyurethane film, which permits a controlled leakage into a secondary absorbent dressing. The study included 30 adult patients. Skin graft donor sites at the proximal thigh were dressed with the modified film dressing. Our results indicate that this dressing concept is associated with a reliable, rapid rate of epithelization. Both, controlled leakage and minimal pain caused particular comfort for patients and ward staff. Furthermore, this dressing was also suited for differently shaped and large donor sites. We conclude that the modification results in a more practicable, comfortable, and cost-effective film dressing, which requalifies the polyurethane film as an ideal dressing material for split-thickness skin graft donor sites. PMID:19571740

  5. Effect of different surfactants and thicknesses on electrodeposited films of bismuth telluride and its thermoelectric performance

    NASA Astrophysics Data System (ADS)

    Kulsi, Chiranjit; Mitra, Mousumi; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali; Goswami, Shyamaprosad

    2015-10-01

    Thin films of bismuth telluride using various surfactants such as sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP) have been electrochemically deposited. The influence of different surfactants on crystal orientation and morphology was investigated and correlated with the thermoelectric performance of the electrodeposited films. Since thickness affects the thermoelectric performance compared to the surfactant, thickness- dependent thermoelectric performance has also been investigated. The carrier mobilities of the films obtained are significantly enhanced due to improved surface morphology using different surfactants. Between the two surfactants, films with SDS exhibited the higher value of thermoelectric power, power factor, and figure of merit, which is due to the effect of micelle formation. The XRD pattern of all the films, which are electrodeposited without surfactant or using SDS and PVP, showed preferred crystal orientation along the (018) direction. The roles of organic molecules in the development of nanoparticles with improved thermoelectric properties have been investigated.

  6. Influence of underneath pentacene thickness on performance of p-n heterojunction organic thin film transistors

    NASA Astrophysics Data System (ADS)

    Zhou, Jianlin; Jiang, Yuyu; Wang, Zhen; Hu, Shengdong; Gan, Ping; Shen, Xiaoqing

    2016-02-01

    Organic thin film transistors (OTFTs) with heterojunction semiconducting layers composed of p-type pentacene and n-type fluorinated copper phthalocyanine (F16CuPc) have been fabricated. The influence of pentacene film thickness on performance of transistors is carefully investigated. It has been found that, with the increase of pentacene film thickness, the electron mobility increases at first and then decreases intensely. But the shift of VT is opposite comparing with electron mobility. The performance improvement can be attributed to the increase of free electron carriers by band bending at the pentacene/F16CuPc interface, and better F16CuPc film quality grown upon pentacene. Comparing with island growth-mode, layer-by-layer growth-mode of pentacene facilitates the growth of the upper F16CuPc film.

  7. Improved gas sensing and dielectric properties of Fe doped hydroxyapatite thick films: Effect of molar concentrations

    SciTech Connect

    Mene, Ravindra U.; Mahabole, Megha P.; Mohite, K.C.; Khairnar, Rajendra S.

    2014-02-01

    Highlights: • We report improved gas sensing and dielectric characteristics of Fe ion exchanged HAp films. • Fe doped HAp film shows maximum gas response at relatively lower temperature. • Response and gas uptake capacity of sensors is improved for appropriate amount of Fe ions in HAp matrix. • Fe-HAp films exhibit remarkable improvement in dielectric properties compared to pure HAp. • Fe doped HAp films show significant improvement in gas sensing as well as in dielectric properties. - Abstract: In the present work Fe doped hydroxyapatite (Fe-HAp) thick films has been successfully utilized to improve the gas sensing as well as its dielectric properties. Initially, HAp nano powder is synthesized by chemical precipitation process and later on Fe ions are doped in HAp by ion exchange process. Structural and morphological modifications are observed by means of X-ray diffraction and scanning electron microscopy analysis. The sensing parameters such as operating temperature, response/recovery time and gas uptake capacity are experimentally determined. The Fe-HAp (0.05 M) film shows improved CO and CO{sub 2} gas sensing capacity at lower operating temperature compared to pure HAp. Moreover, variation of dielectric constant and dielectric loss for pure and Fe-HAp thick films are studied as a function of frequency in the range of 10 Hz–1 MHz. The study reveals that Fe doped HAp thick films improve the sensing and dielectric characteristics as compared to pure HAp.

  8. Structure and friction of stearic acid and oleic acid films adsorbed on iron oxide surfaces in squalane.

    PubMed

    Doig, Michael; Warrens, Chris P; Camp, Philip J

    2014-01-14

    The structure and friction of fatty acid surfactant films adsorbed on iron oxide surfaces lubricated by squalane are examined using large-scale molecular dynamics simulations. The structures of stearic acid and oleic acid films under static and shear conditions, and at various surface coverages, are described in detail, and the effects of unsaturation in the tail group are highlighted. At high surface coverage, the measured properties of stearic acid and oleic acid films are seen to be very similar. At low and intermediate surface coverages, the presence of a double bond, as in oleic acid, is seen to give rise to less penetration of lubricant in to the surfactant film and less layering of the lubricant near to the film. The kinetic friction coefficient is measured as a function of shear rate within the hydrodynamic (high shear rate) lubrication regime. Lubricant penetration and layering are observed to be correlated with friction coefficient. The friction coefficient with oleic acid depends only weakly on surface coverage, while stearic acid admits more lubricant penetration, and its friction coefficient increases significantly with decreasing surface coverage. Connections between film structure and friction are discussed. PMID:24364665

  9. Unusual Contact-Line Dynamics of Thick Films and Drops

    NASA Technical Reports Server (NTRS)

    Veretennikov, Igor; Agarwal, Abhishek; Indeikina, Alexandra; Chang, Hsueh-Chia

    1999-01-01

    We report several novel phenomena In contact-line and fingering dynamics of macroscopic spinning drops and gravity-driven films with dimensions larger than the capillary length. It is shown through experimental and theoretical analysis that such macroscopic films can exhibit various interfacial shapes, including multi valued ones, near the contact line due to a balance between the external body forces with capillarity. This rich variety of front shapes couples with the usual capillary, viscous, and intermolecular forces at the contact line to produce a rich and unexpected spectrum of contact-line dynamics. A single finger develops when part of the front becomes multivalued on a partially wetting macroscopic spinning drop in contrast to a different mechanism for microscopic drops of completely wetting fluids. Contrary to general expectation, we observe that, at high viscosity and low frequencies of rotation, the speed of a glycerine finger increases with increasing viscosity. Completely wetting Dow Corning 200 Fluid spreads faster over a dry inclined plane than a prewetted one. The presence of a thin prewetted film suppresses fingering both for gravity-driven flow and for spin coating. We analyze some of these unique phenomena in detail and offer qualitative physical explanations for the others.

  10. Film Thickness Prediction in an Annular Two-Phase Flow Through Bends

    NASA Astrophysics Data System (ADS)

    Tkaczyk, P. M.; Morvan, H. P.

    2010-09-01

    A finite volume method-based CFD model has been developed in the commercial code Star CD to simulate the annular gas-liquid flow through the 30°, 60° and 90° bends. The liquid film is solved explicitly by means of a modified Volume of Fluid (VOF) method. The droplets are traced using a Lagrangian technique. The film to droplets (entrainment) and droplets to film (stick, bounce, spread and splash) interactions are taken into account using sub-models to complement the VOF model. A good agreement is found between the computed film thickness value and those cited in the literature.

  11. High loading of nanostructured ceramics in polymer composite thick films by aerosol deposition

    PubMed Central

    2012-01-01

    Low temperature fabrication of Al2O3-polyimide composite substrates was carried out by an aerosol deposition process using a mixture of Al2O3 and polyimide starting powders. The microstructures and dielectric properties of the composite thick films in relation to their Al2O3 contents were characterized by X-ray diffraction analysis. As a result, the crystallite size of α-Al2O3 calculated from Scherrer's formula was increased from 26 to 52 nm as the polyimide ratio in the starting powders increased from 4 to 12 vol.% due to the crushing of the Al2O3 powder being reduced by the shock-absorbing effect of the polyimide powder. The Al2O3-polyimide composite thick films showed a high loss tangent with a large frequency dependence when a mixed powder of 12 vol.% polyimide was used due to the nonuniform microstructure with a rough surface. The Al2O3-polyimide composite thick films showed uniform composite structures with a low loss tangent of less than 0.01 at 1 MHz and a high Al2O3 content of more than 75 vol.% when a mixed powder of 8 vol.% polyimide was used. Moreover, the Al2O3-polyimide composite thick films had extremely high Al2O3 contents of 95 vol.% and showed a dense microstructure close to that of the Al2O3 thick films when a mixed powder of 4 vol.% polyimide was used. PMID:22283973

  12. Study of PZT thick-film infrared detectors prepared by MEMS technology

    NASA Astrophysics Data System (ADS)

    Qiang, Xiang-Peng; Chuan, Gui-Wu; Wen, Bo-Luo; Wan, Li-Zhang; Jia, Qiang-Cao

    2011-08-01

    In this paper, a single element integrated infrared detector using screen printed lead zirconate titanate (PZT) thick films on Pt/Ti/Al2O3/SiO2 coated silicon cup has been developed. The thermal insulating micro-bridge of the detector was prepared by Micro-electro-mechanical System (MEMS) technology. To increase the density of PZT ceramic thick films, cool isostatic pressing experiments had been conducted under 300MPa and 30s dwell time. The XRD pattern shows that PZT thick films possess good perovskite structure. The SEM cross section image demonstrate that the PZT film was dense and the thickness is about 25μm. The dielectric constant, loss and pyroelectric coefficient of PZT thick films prepared at optimized conditions is 1100, 1% and 1×10-8C/Kcm 2, respectively. The results indicated that the PZT thermal sensitive layer fabricated by screen printing on the Pt/Ti coated silicon cup with micro-bridge thermal insulation structure, and Al2O3/SiO2 barrier layer show potential application in infrared detectors.

  13. Disappearance of ferroelectric critical thickness in epitaxial ultrathin BaZr O3 films

    NASA Astrophysics Data System (ADS)

    Zhang, Yajun; Li, Gui-Ping; Shimada, Takahiro; Wang, Jie; Kitamura, Takayuki

    2014-11-01

    The intrinsic critical ferroelectric thickness of epitaxial ultrathin capacitors of incipient ferroelectric BaZr O3 (BZO) films with realistic SrRu O3 (SRO) electrodes is investigated by first-principles calculations based on density functional theory. We reveal that polarization can stably exist even in one-unit-cell thick BZO films, i.e., absence of critical thickness, whereas the widely investigated proper ferroelectrics like BaTi O3 and SrTi O3 films have no polarization. The influences of realistic ferroelectric-electrode interface and misfit strain on the ionic and electronic structures of the BZO-SRO thin film system have been examined under the short-circuited boundary condition. It is found that the ionic polarization of conductive SRO electrodes can effectively strengthen the screening of bound charges at the interface, which greatly reduces the depolarization field in the BZO films. Furthermore, the epitaxial misfit strain remarkably enhances the polarization through the enhancement of hybridization of Zr and O electron orbitals, resulting in the disappearance of ferroelectric critical thickness. Our findings are beyond the critical thickness of proper ferroelectrics and are thus promising for future nanometer-scale ferroelectric device such as high-density ferroelectric memory.

  14. Enhanced film thickness for Néel wall in soft magnetic film by introducing strong magnetocrystalline anisotropy.

    PubMed

    Xu, Fei; Wang, Tao; Ma, Tianyong; Wang, Ying; Zhu, Shimeng; Li, Fashen

    2016-01-01

    This study investigated the magnetic domain walls in a single-layer soft magnetic film with strong magnetocrystalline anisotropy energy. The soft magnetic film is composed of a highly c-axis-oriented hcp-Co81Ir19 alloy with strong negative magnetocrystalline anisotropy. The domain structure of the soft Co81Ir19 films with thickness ranging from 50-230 nm in a demagnetization state was observed through magnetic force microscopy and Lorentz transmission electron microscopy. Results reveal that the critical transition thickness at which the domain wall changes from Néel type to Bloch type is about 138 nm, which is much larger than the critical value of traditional Fe- and Co-based soft magnetic films with negligible magnetocrystalline anisotropy. Theoretical calculation was also performed and the calculated result agrees well with experimental data. PMID:26821614

  15. Enhanced film thickness for Néel wall in soft magnetic film by introducing strong magnetocrystalline anisotropy

    PubMed Central

    Xu, Fei; Wang, Tao; Ma, Tianyong; Wang, Ying; Zhu, Shimeng; Li, Fashen

    2016-01-01

    This study investigated the magnetic domain walls in a single-layer soft magnetic film with strong magnetocrystalline anisotropy energy. The soft magnetic film is composed of a highly c-axis-oriented hcp-Co81Ir19 alloy with strong negative magnetocrystalline anisotropy. The domain structure of the soft Co81Ir19 films with thickness ranging from 50–230 nm in a demagnetization state was observed through magnetic force microscopy and Lorentz transmission electron microscopy. Results reveal that the critical transition thickness at which the domain wall changes from Néel type to Bloch type is about 138 nm, which is much larger than the critical value of traditional Fe- and Co-based soft magnetic films with negligible magnetocrystalline anisotropy. Theoretical calculation was also performed and the calculated result agrees well with experimental data. PMID:26821614

  16. Thermal Conductivity Measurement of Xe-Implanted Uranium Dioxide Thick Films using Multilayer Laser Flash Analysis

    SciTech Connect

    Nelson, Andrew T.

    2012-08-30

    The Fuel Cycle Research and Development program's Advanced Fuels campaign is currently pursuing use of ion beam assisted deposition to produce uranium dioxide thick films containing xenon in various morphologies. To date, this technique has provided materials of interest for validation of predictive fuel performance codes and to provide insight into the behavior of xenon and other fission gasses under extreme conditions. In addition to the structural data provided by such thick films, it may be possible to couple these materials with multilayer laser flash analysis in order to measure the impact of xenon on thermal transport in uranium dioxide. A number of substrate materials (single crystal silicon carbide, molybdenum, and quartz) containing uranium dioxide films ranging from one to eight microns in thickness were evaluated using multilayer laser flash analysis in order to provide recommendations on the most promising substrates and geometries for further investigation. In general, the uranium dioxide films grown to date using ion beam assisted deposition were all found too thin for accurate measurement. Of the substrates tested, molybdenum performed the best and looks to be the best candidate for further development. Results obtained within this study suggest that the technique does possess the necessary resolution for measurement of uranium dioxide thick films, provided the films are grown in excess of fifty microns. This requirement is congruent with the material needs when viewed from a fundamental standpoint, as this length scale of material is required to adequately sample grain boundaries and possible second phases present in ceramic nuclear fuel.

  17. Conformation-triggered flow instability in monolayer thick polymer films

    NASA Astrophysics Data System (ADS)

    Sheiko, Sergei; Beers, Kathryn; Matyjaszewski, Krzysztof; Rubinstein, Michael; Dobrynin, Andrey

    2005-03-01

    Here we have report on a new type of flow instability triggered by conformational changes of brush-like macromolecules as they spread on a solid substrate. By tracing the movement of individual molecules by atomic force microscopy, we were able to follow the evolution of the instability pattern on the molecular level enabling a microscopic understanding of the underlying physical mechanism. The instability is an analog of the Saffman-Taylor instability in thin films. However, the instability is driven by a variation in flow velocity controlled by molecular conformation instead of a viscosity gradient.

  18. Terahertz ultrathin film thickness sensor below λ/90 based on metamaterial.

    PubMed

    Chen, Meng; Fan, Fei; Shen, Si; Wang, Xianghui; Chang, Shengjiang

    2016-08-10

    The film thickness sensing based on metamaterial is investigated in the terahertz (THz) region. We fabricated the metamaterial sensor, and demonstrated its resonance by using the THz time-domain spectroscopy system. The results show that the resonant dip redshifts as the film thickness increases, which achieves reliable film sensing in the THz band. Its sensitivity is larger than 9.4 GHz/μm with a film thinner than λ/90. Meanwhile, the sensing mechanism is revealed by the simulation of near-field resonance distribution, which shows that the resonant intensity is stronger when the field is closer to the interface between the metamaterial surface and polyvinyl alcohol film. Therefore, the nonlinear type of the sensing sensitivity in our experiment can be well explained, and a higher sensitive sensing can be obtained when the film thickness is smaller. This simple and flexible method can realize the ultrathin film sensing in the THz region, and has application potential in the real-time monitoring of sample quality. PMID:27534497

  19. Yttrium Iron Garnet Thick Films Formed by the Aerosol Deposition Method for Microwave Inductors

    NASA Astrophysics Data System (ADS)

    Johnson, Scooter; Newman, Harvey; Glaser, E. R.; Cheng, Shu-Fan; Tadjer, Marko; Kub, Fritz; Eddy, Charles, Jr.

    2014-03-01

    We have employed the aerosol deposition method (ADM) to direct-write 40 μm-thick polycrystalline films of yttrium iron garnet (YIG, Y3Fe5O12) at room temperature onto patterned gold inductors on sapphire substrates at a deposition rate of 1-3 μm/min as a first step toward integration into microwave magnetic circuits. A challenge to integrating magnetic films into current semiconductor technology is the high-temperature regime (900-1400°C) at which conventional ferrite preparation takes place. The ability of the ADM to form dense, thick films at room temperature makes this a promising approach for integrated magnetics where low-temperature deposition and thick films are required. The ADM YIG film has an rms roughness of 3-4 μm, is comprised of nano-crystalline grains with a density 50% of the theoretical value. XRD patterns of the as-deposited film and starting powder indicate a polycrystalline single-phase film. In-plane VSM and FMR measurements reveal a saturation of 22 emu/g, coercivity of 27 Oe, and linewidth of 360 Oe. Early measurements of air-filled and YIG-filled gold inductors between 0.01-10 GHz indicate an improved inductance of nearly a factor of 2 at low frequency. At higher frequency, resonance effects diminish this improvement. This work is sponsored by the Office of Naval Research under program number N0001413WX20845 (Dr. Daniel Green, Program Manager).

  20. Layer-by-layer Assembly of Thick, Cu2+-Chelating Films

    PubMed Central

    Wijeratne, Salinda; Bruening, Merlin L.; Baker, Gregory L.

    2013-01-01

    Layer-by-layer adsorption of protonated poly(allylamine) (PAH) and deprotonated poly(N,N-dicarboxymethylallyl amine) (PDCMAA) yields thick films with a high density of iminodiacetic acid (IDA) ligands that bind metal ions. When film deposition occurs at pH 3.0, PAH/PDCMAA bilayer thicknesses reach 200 nm, and Cu2+ binding capacities are ~2.5 mmoles per cm3 of film. (PAH/PDCMAA)10 films deposited at pH 3.0 are 4- to 8-fold thicker than films formed at pH 5.0, 7.0, or 9.0, presumably because of the low charge density on PDCMAA chains at pH 3.0. However, with normalization to film thickness, all films bind similar amounts of Cu2+ from pH 4.1 solutions of CuSO4. In μm-thick films, equilibration of binding sites with Cu2+ requires ~4 h due to a low Cu2+ diffusion coefficient (~2.6×10−12 cm2/sec). Sorption isotherms determined at several temperatures show that Cu2+ binding is endothermic with a positive entropy (binding constants increase with increasing temperature), presumably because metal-ion complexation involves displacement of both a proton from IDA and water molecules from Cu2+. (PAH/PDCMAA)10 films retain their binding capacity over 4 absorption/elution cycles and may prove useful in metal-ion scavenging, catalysis, and protein binding. PMID:24044576

  1. The effect of film thickness on the optical absorption edge and optical constants of the Cr(III) organic thin films

    NASA Astrophysics Data System (ADS)

    Yakuphanoglu, F.; Sekerci, M.; Balaban, A.

    2005-05-01

    The effect of film thickness on optical properties of the Cr(III) complex having 2-pyridincarbaldehye thiosemicarbazone thin films was investigated. The analyses of the optical absorption data revealed existence of direct and indirect transitions in the optical band gap. The optical constants (refractive index and dielectric constant) of the thin films were determined. The thickness of the films causes important changes in refractive index and real part-imaginary parts of the dielectric constant. The most significant result of the present study is to indicate that thickness of the film can be used to modify in the optical band gaps and optical constant of the thin films.

  2. (100)-Textured KNN-based thick film with enhanced piezoelectric property for intravascular ultrasound imaging

    PubMed Central

    Zhu, Benpeng; Zhang, Zhiqiang; Ma, Teng; Yang, Xiaofei; Li, Yongxiang; Shung, K. Kirk; Zhou, Qifa

    2015-01-01

    Using tape-casting technology, 35 μm free-standing (100)-textured Li doped KNN (KNLN) thick film was prepared by employing NaNbO3 (NN) as template. It exhibited similar piezoelectric behavior to lead containing materials: a longitudinal piezoelectric coefficient (d33) of ∼150 pm/V and an electromechanical coupling coefficient (kt) of 0.44. Based on this thick film, a 52 MHz side-looking miniature transducer with a bandwidth of 61.5% at −6 dB was built for Intravascular ultrasound (IVUS) imaging. In comparison with 40 MHz PMN-PT single crystal transducer, the rabbit aorta image had better resolution and higher noise-to-signal ratio, indicating that lead-free (100)-textured KNLN thick film may be suitable for IVUS (>50 MHz) imaging. PMID:25991874

  3. (100)-Textured KNN-based thick film with enhanced piezoelectric property for intravascular ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Zhu, Benpeng; Zhang, Zhiqiang; Ma, Teng; Yang, Xiaofei; Li, Yongxiang; Shung, K. Kirk; Zhou, Qifa

    2015-04-01

    Using tape-casting technology, 35 μm free-standing (100)-textured Li doped KNN (KNLN) thick film was prepared by employing NaNbO3 (NN) as template. It exhibited similar piezoelectric behavior to lead containing materials: a longitudinal piezoelectric coefficient (d33) of ˜150 pm/V and an electromechanical coupling coefficient (kt) of 0.44. Based on this thick film, a 52 MHz side-looking miniature transducer with a bandwidth of 61.5% at -6 dB was built for Intravascular ultrasound (IVUS) imaging. In comparison with 40 MHz PMN-PT single crystal transducer, the rabbit aorta image had better resolution and higher noise-to-signal ratio, indicating that lead-free (100)-textured KNLN thick film may be suitable for IVUS (>50 MHz) imaging.

  4. Translational Diffusion in Supported Rubberly Polymer Films at Different Layer Thicknesses

    NASA Astrophysics Data System (ADS)

    Pak, Hunkyun; Ellingson, Peter Christopher; Yu, Hyuk

    2002-03-01

    Translational diffusion of an organic dye with C18 hydrocarbon tail (4-octadecylamino-NBD) is examined in thin films of poly(isoprene) and poly(dimethylsiloxane) spincast on substrates. Surface functionalized silicon wafers were used as the substrates. Two kinds of surface functionalized wafers, one with predominantly methyl group and the other with primary amine group, were examined with respect to the diffusion as a function of film thickness over a range of 10-2000 nm. The diffusion coefficient was determined by the technique of fluorescence recovery after photobleaching and the film thickness by ellipsometry. The diffusion coefficient is found to reduce substantially from that in bulk polymers, vary by an order of magnitude over the thickness range, and its dependence is analyzed in terms of a simple model that takes into account of polymer interactions with the functionalized surfaces.

  5. Thickness dependent optical and electrical properties of CdSe thin films

    NASA Astrophysics Data System (ADS)

    Purohit, A.; Chander, S.; Nehra, S. P.; Lal, C.; Dhaka, M. S.

    2016-05-01

    The effect of thickness on the optical and electrical properties of CdSe thin films is investigated in this paper. The films of thickness 445 nm, 631 nm and 810 nm were deposited on glass and ITO coated glass substrates using thermal evaporation technique. The deposited thin films were thermally annealed in air atmosphere at temperature 100°C and were subjected to UV-Vis spectrophotometer and source meter for optical and electrical analysis respectively. The absorption coefficient is observed to increase with photon energy and found maximum in higher photon energy region. The extinction coefficient and refractive index are also calculated. The electrical analysis shows that the electrical resistivity is observed to be decreased with thickness.

  6. Development of BZO Doped YGdBCO Thick Films Using TFA-MOD Process

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Nakahata, K.; Yoshizumi, M.; Izumi, T.; Shiohara, Y.; Kimura, K.; Hasegawa, T.; Kato, T.; Hirayama, T.

    TFA-MOD (Metal Organic Deposition using Trifluoro-acetates) process is of considerable practical concern for future applications since it can fabricate high performance coated conductors (CCs) with low cost. In this study, we developed the process for fabricating thick films in BZO nanoparticle doped Y0.77Gd0.23Ba1.5Cu3Oy (YGdBCO) CCs in order to realize high Ic values under magnetic field. The effect of RTR (Reel To Reel)-dip-coating conditions on microstructure, Jc(-B-θ) properties, etc. was investigated in order to fabricate crack-free thick and high performance films. A BZO doped YGdBCO film with uniform 3.0 μm thickness showed the high in-field Ic and Jc values of 55.6 A/cm-w and 0.18 MA/cm2@77.8K, 3T, respectively.

  7. Micro-Machined High-Frequency (80 MHz) PZT Thick Film Linear Arrays

    PubMed Central

    Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K. Kirk

    2010-01-01

    This paper presents the development of a micro-machined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT solgel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (−6 dB) of 60%. An insertion loss of −41 dB and adjacent element crosstalk of −21 dB were found at the center frequency. PMID:20889407

  8. Wavy film flows down an inclined plane: Perturbation theory and general evolution equation for the film thickness

    SciTech Connect

    Frenkel, A.L.; Indireshkumar, K.

    1999-10-01

    Wavy film flow of incompressible Newtonian fluid down an inclined plane is considered. The question is posed as to the parametric conditions under which the description of evolution can be approximately reduced for all time to a single evolution equation for the film thickness. An unconventional perturbation approach yields the most general evolution equation and least restrictive conditions on its validity. The advantages of this equation for analytical and numerical studies of three-dimensional waves in inclined films are pointed out. {copyright} {ital 1999} {ital The American Physical Society}

  9. Thick film oxidation of copper in an electroplated MEMS process

    NASA Astrophysics Data System (ADS)

    Lazarus, N.; Meyer, C. D.; Bedair, S. S.; Song, X.; Boteler, L. M.; Kierzewski, I. M.

    2013-06-01

    Copper forms a porous oxide, allowing the formation of oxide layers up to tens of microns thick to be created at modest processing temperatures. In this work, the controlled oxidation of copper is employed within an all-metal electroplating process to create electrically insulating, structural posts and beams. This capability could eliminate the additional dielectric deposition and patterning steps that are often needed during the construction of sensors, waveguides, and other microfabricated devices. In this paper, copper oxidation rates for thermal and plasma-assisted growth methods are characterized. Time control of the oxide growth enables larger copper structures to remain conductive while smaller copper posts are fully oxidized. The concept is demonstrated using the controlled oxidation of a copper layer between two nickel layers to fabricate nickel inductors having both copper electrical vias and copper oxide support pillars. Nickel was utilized in this demonstration for its resistance against low temperature oxidation and interdiffusion with copper.

  10. Effect of structure on the electrical resistance of thick films based on doped tin dioxide

    SciTech Connect

    Dyshel', D.E.; Rud', B.M.; Smirnov, V.P.; Smolin, M.D.

    1986-03-01

    The authors prepared thick-film elements according to the standard; the films were 30-35 ..mu..m thick. The paste consisted of powders of the solid solution of the system snO/sup 2/-Sb/sub 2/O/sub 5/ and the content of antimony pentoxide was 7 mass %. It was shown that particles of the conducting phase are practically uniformly distributed in the glass matrix. Films obtained at heat-treatment temperatures not lower than 1090 K had the lowest absolute values of the temperature coefficient of the resistance. Increasing the glass content in the mixture and decreasing the specific surface area of the powder of the conducting phase was found to increase the resistivity of the films.

  11. Fabrication and properties of FePt thick films for alternative local field micromagnet

    SciTech Connect

    Jang, Pyungwoo; Lee, Bonghan; Seomoon, Kyu; Rhie, Kungwon; Choi, Sungwon

    2009-04-01

    Growth of FePt films thicker than several tens of a micrometer was attempted on Fe substrates for the use of micromagnets. Several underlayer or intermediate layers were found to be totally ineffective to success. However, 20 {mu}m thick FePt films on the Fe substrates were successfully grown by sputtering after HF surface treatment. (BH){sub max} of the non-annealed film was about 10.7 MG Oe under a maximum applied field of 10 kOe. An excellent adhesion between the Fe substrate and the FePt thick films seems to be due to both improvement of surface cleanliness and roughening which enhanced the chemical and physical bonding strengths.

  12. Critical detonation thickness in vapor-deposited hexanitroazobenzene (HNAB) films with different preparation conditions

    NASA Astrophysics Data System (ADS)

    Tappan, Alexander; Knepper, Robert; Marquez, Michael; Ball, J.; Miller, Jill

    2013-06-01

    At Sandia National Laboratories, we have coined the term ``microenergetics'' to describe sub-millimeter energetic material studies aimed at gaining knowledge of combustion and detonation behavior at the mesoscale. Films of the high explosive hexanitroazobenzene (HNAB) have been deposited through physical vapor deposition. HNAB deposits in an amorphous state that crystallizes over time and modest heating accelerates this crystallization. HNAB films were prepared under different crystallization temperatures, and characterized with surface profilometry and scanning electron microscopy. The critical detonation thickness for HNAB at different crystallization conditions was determined in a configuration where charge width was large compared to film thickness, and thus side losses did not play a role in detonation propagation. The results of these experiments will be discussed in the context of small sample geometry, deposited film morphology, crystal structure, and density.

  13. Thickness effect on structure and properties of ZAO thin films by RF magnetron sputtering at different substrate temperatures

    NASA Astrophysics Data System (ADS)

    Zhu, B. L.; Zhu, S. J.; Wang, J.; Wu, J.; Zeng, D. W.; Xie, C. S.

    2011-07-01

    Al-doped ZnO (ZAO) films, having film thickness of about 50-1200 nm, were deposited at substrate temperature of 100-300 °C by radio-frequency magnetron sputtering. Structural, electrical, and optical properties of as-deposited ZAO films have been studied as a function of film thickness and substrate temperature. The investigation of X-ray diffraction indicates that the crystalline quality of the film improves and its stress relaxes with increasing film thickness or substrate temperature, and preferred (0 0 2) orientation is found at substrate temperature above 100 °C. By the observation under scanning electron microscope, columnar structure can be obviously observed from cross-section of the films with increasing film thickness at substrate temperature above 100 °C; the surface morphology can exhibit nanocrystalline, honeycomb, or hillock structure, depending on film thickness and substrate temperature. Hall effect measurements reveal that the decrease of resistivity of the film is generally accompanied by the increase of carrier concentration and mobility with increasing film thickness or substrate temperature. It is speculated that the main scattering mechanism in as-deposited ZAO films is intercrystallite boundary scattering. The transmission spectra measurements of ZAO films indicate that average transmittance between 400 and 800 nm decreases from about 86% to 70% with increase in film thickness. The obtained energy gap ( Eg) of the films at different substrate temperatures is found in order of 200 °C>300 °C>100 °C, which can be attributed to high carrier concentration and compressive stress at 200 °C, but markedly low carrier concentration at 100 °C. With increase in film thickness, the decrease in compressive stress and/or increase in crystallite size result in the decreased or unchanged tendency of Eg of the films although the carrier concentration increases.

  14. Electroplated Fe-Pt thick films prepared in plating baths with various pH values

    NASA Astrophysics Data System (ADS)

    Yanai, T.; Furutani, K.; Masaki, T.; Ohgai, T.; Nakano, M.; Fukunaga, H.

    2016-05-01

    Fe-Pt thick-films were electroplated on a Ta substrate using a direct current, and the effect of the pH value of the plating bath on the magnetic properties of the films was evaluated. For the films prepared from the baths with the same bath composition, the Fe composition and the thickness increased with increasing the pH value. In order to remove the effect of the change in the film composition on the magnetic properties, we controlled the film composition at approximately Fe50Pt50 or Fe60Pt40 by the change in the amount of the iron sulfate. The remanence of the annealed Fe60Pt40 films did not depend on the pH value clearly, and showed almost constant value of 0.75 T. We obtained the large coercivity of approximately 460 kA/m in the pH value from 4 to 7. Since the Fe52Pt48 film prepared at pH ≈ 4 shows much higher (BH)max value of 70 kJ/m3 than that of 57 kJ/m3 for our previously-reported Fe50Pt50 film (pH ≈ 2), we concluded that slight higher pH value than not-adjusted one (pH ≈ 2) is effective to increase the coercivity.

  15. Some limitations in applying classical EHD film-thickness formulae to a high-speed bearing

    NASA Technical Reports Server (NTRS)

    Coy, J. J.; Zaretsky, E. V.

    1980-01-01

    Elastohydrodynamic film thickness was measured for a 20 mm ball bearing using the capacitance technique. The bearing was thrust loaded to 90, 448, and 778 N. The corresponding maximum stresses on the inner race were 1.28, 2.09, and 2.45 GPa. Test speeds ranged from 400 to 14,000 rpm. Film thickness measurements were taken with four different lubricants: (1) synthetic paraffinic; (2) synthetic paraffinic with additives; (3) neopentylpolyol (tetra) ester; and (4) synthetic cycloaliphatic hydrocarbon traction fluid. The test bearing was mist lubricated. Test temperatures were 300, 338, and 393 K. The measured results were compared to theoretical predictions and are presented.

  16. Effects of supply conditions on film thickness in lubricated Hertzian contacts

    NASA Technical Reports Server (NTRS)

    Dalmaz, G.; Godet, M.

    1980-01-01

    A generalization of the hydrodynamic expression for Hertzian contacts is described and various methods for calculating the thickness of the oil film winter steady-state, isothermal conditions are given. This is important for engineering applications such as gears and bearings because these results are closer to real operating conditions. Theories of lubrication are discussed, and the mathematics involved are presented using approximately 30 equations and 13 figures. For lubricated, linear, elliptical or point Hertzian contacts it is demonstrated how to calculate the thickness of the oil film at the center of the contact for steady-state isothermal conditions.

  17. Gauge factor enhancement driven by heterogeneity in thick-film resistors

    SciTech Connect

    Grimaldi, C.; Ryser, P.; Strassler, S.

    2001-07-01

    We present a simple picture of the gauge factor (GF) enhancement in highly heterogeneous materials such as thick-film resistors. We show that when the conducting phase is stiffer than the insulating one, the local strains within the latter are enhanced with respect to the averaged macroscopic strain. Within a simple model of electron tunneling processes, we show that the enhanced local strain leads to values of GF higher than those expected for a homogeneous system. Moreover, we provide formulas relating the enhancement of GF to the elastic and microstructural characteristics of thick-film resistors. {copyright} 2001 American Institute of Physics.

  18. Evaluation of the EHL Film Thickness and Extreme Pressure Additives on Gear Surface Fatigue Life

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.; Shimski, John

    1994-01-01

    Surface pitting fatigue life tests were conducted with seven lubricants, using AISI 9310 spur gears. The test lubricants can be classified as synthetic polyol-esters with various viscosities and additive packages. The lubricant with a viscosity that provided a specific film thickness greater than one and with an additive package produced gear surface fatigue lives that were 8.6 times that for lubricants with a viscosity that provided specific film thickness less than one. Lubricants with the same viscosity and similar additive packages gave equivalent gear surface fatigue lives.

  19. Real-time holographic gratings modulate with voltage by different thickness film

    NASA Astrophysics Data System (ADS)

    Fontanilla-Urdaneta, Rosangela C.; Olivares-Pérez, Arturo; Fuentes-Tapia, Israel

    2011-04-01

    The holographic gratings on photopolymer films are studied by three different thicknesses for samples A, B, and C. The photopolymer emulsion is prepared with potassium dichromate and nickel (II) chloride hexahydrate in polyvinyl alcohol matrix. The evolution of diffraction efficiency is evaluated during holographic recording with and without voltage as a function of energy exposure by changing the thickness. The curves of diffraction efficiency reach a peak when the films are continuously exposed to energy for a period of time. Sample B obtains the highest diffraction efficiency

  20. Measurements of liquid film thickness, concentration, and temperature of aqueous urea solution by NIR absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Pan, R.; Jeffries, J. B.; Dreier, T.; Schulz, C.

    2016-01-01

    A multi-wavelength near-infrared (NIR) diode laser absorption sensor has been developed and demonstrated for real-time monitoring of the thickness, solute concentration, and temperature of thin films of urea-water solutions. The sensor monitors the transmittance of three near-infrared diode lasers through the thin liquid film. Film thickness, urea mass fraction, and liquid temperature were determined from measured transmittance ratios of suitable combinations of lasers. Available laser wavelengths were selected depending on the variation of the NIR absorption spectrum of the solution with temperature and solute concentration. The spectral database was measured by a Fourier transform infrared spectrometer in the range 5500-8000 cm-1 for urea solutions between 5 and 40 wt% and temperatures between 298 and 338 K. A prototype sensor was constructed, and the sensor concept was first validated with measurements using a calibration cell providing liquid layers of variable thickness (200-1500 µm), urea mass fraction (5-40 wt%) and temperature (298-318 K). Temporal variations of film thickness and urea concentration were captured during the constant-temperature evaporation of a liquid film deposited on an optically polished heated quartz flat.

  1. Thick adherent dielectric films on plastic substrates and method for depositing same

    DOEpatents

    Wickboldt, Paul; Ellingboe, Albert R.; Theiss, Steven D.; Smith, Patrick M.

    2002-01-01

    Thick adherent dielectric films deposited on plastic substrates for use as a thermal barrier layer to protect the plastic substrates from high temperatures which, for example, occur during laser annealing of layers subsequently deposited on the dielectric films. It is desirable that the barrier layer has properties including: a thickness of 1 .mu.m or greater, adheres to a plastic substrate, does not lift-off when cycled in temperature, has few or no cracks and does not crack when subjected to bending, resistant to lift-off when submersed in fluids, electrically insulating and preferably transparent. The thick barrier layer may be composed, for example, of a variety of dielectrics and certain metal oxides, and may be deposited on a variety of plastic substrates by various known deposition techniques. The key to the method of forming the thick barrier layer on the plastic substrate is maintaining the substrate cool during deposition of the barrier layer. Cooling of the substrate maybe accomplished by the use of a cooling chuck on which the plastic substrate is positioned, and by directing cooling gas, such as He, Ar and N.sub.2, between the plastic substrate and the cooling chucks. Thick adherent dielectric films up to about 5 .mu.m have been deposited on plastic substrates which include the above-referenced properties, and which enable the plastic substrates to withstand laser processing temperatures applied to materials deposited on the dielectric films.

  2. Measurement of thickness of thin water film in two-phase flow by capacitance method

    SciTech Connect

    Sun, R.K.; Kolbe, W.F.; Leskovar, B.; Turko, B.

    1981-09-01

    A technique has been developed for measuring water film thickness in a two-phase annular flow system by the capacitance method. An experimental model of the flow system with two types of electrodes mounted on the inner wall of a cylindrical tube has been constructed and evaluated. The apparatus and its ability to observe fluctuations and wave motions of the water film passing over the electrodes is described in some detail.

  3. Simple and precise measurement of the complex refractive index and thickness for thin films

    NASA Astrophysics Data System (ADS)

    Peng, Yu; Li, Wei

    2014-07-01

    We demonstrate applications of a novel scheme which is used for measuring refractive index and thickness of thin film by analyzing the relative phase difference and reflected ratio at reflection point of a monolithic folded Fabry-Perot cavity (MFC). The complex refractive index and the thickness are calculated according to the Fresnel formula. Results show that the proposed method has an improvement in accuracy with simple and clear operating process compared with the conventional Ellipsometry.

  4. Surface functionalization by fine ultraviolet-patterning of nanometer-thick liquid lubricant films

    NASA Astrophysics Data System (ADS)

    Lu, Renguo; Zhang, Hedong; Komada, Suguru; Mitsuya, Yasunaga; Fukuzawa, Kenji; Itoh, Shintaro

    2014-11-01

    For micro/nanoscale devices, surface functionalization is essential to achieve function and performance superior to those that originate from the inherent bulk material properties. As a method of surface functionalization, we dip-coated nanometer-thick liquid lubricant films onto solid surfaces and then patterned the lubricant films with ultraviolet (UV) irradiation through a photomask. Surface topography, adhesion, and friction measurements demonstrated that the patterned films feature a concave-convex thickness distribution with thicker lubricant in the irradiated regions and a functional distribution with lower adhesion and friction in the irradiated convex regions. The pattern linewidth ranged from 100 to as fine as 0.5 μm. The surface functionalization effect of UV-patterning was investigated by measuring the water contact angles, surface energies, friction forces, and depletion of the patterned, as-dipped, and full UV-irradiated lubricant films. The full UV-irradiated lubricant film was hydrophobic with a water contact angle of 102.1°, and had lower surface energy, friction, and depletion than the as-dipped film, which was hydrophilic with a water contact angle of 80.7°. This demonstrates that UV irradiation substantially improves the surface and tribological properties of the nanometer-thick liquid lubricant films. The UV-patterned lubricant films exhibited superior surface and tribological properties than the as-dipped film. The water contact angle increased and the surface energy, friction, and depletion decreased as the pattern linewidth decreased. In particular, the 0.5-μm patterned lubricant film even showed a larger water contact angle and lower friction and depletion than the full UV-irradiated film. These indicate that UV-patterning of nanometer-thick lubricant films with a minimized linewidth has a better surface functionalization effect than full UV irradiation. Enhancement of the surface functionalization effect may be attributed to a

  5. Design, Development, and Applications of Image Scanning Ellipsometry for the Measurement of Thin Film Thickness Profiles.

    NASA Astrophysics Data System (ADS)

    Liu, An-Hong

    A novel technique, Image Scanning Ellipsometry, to measure the two dimensional thickness profile of a non -uniform, thin film, from several nm up to several mum, in the transient state as well as in the steady state was developed and tested in this thesis. Image Scanning Ellipsometry (ISE) is a full-field imaging technique which can study every point on the surface at the same time with high spatial resolution and thickness sensitivity; i.e., it can measure and map a liquid or solid film thickness profile in two dimensions. The long-term objective of the development of ISE is to determine the stability and heat transfer characteristics of evaporating thin films. The main purpose of this thesis was to develop the basic concept of ISE and demonstrate its use by measuring the thickness profiles of non-uniform solid films in a steady state as well as the profile of draining liquid films of wetting and partially wetting fluids in a transient state. In this thesis, ISE has been proven to be as accurate as a null ellipsometer by measuring a known solid wedge profile of ThF_4 on a Si substrate. In addition, the ability of ISE to measure liquid draining films such as FC-5311, FC-77, and FC-70 in a transient state was demonstrated. Moreover, ISE was also used to measure a partially wetting, draining film of dodecane, and to record the details of film rupture. The approximate solutions of a modeling equation for the thickness profile during draining was compared to the experimental profile. The agreement between theory and experiment is quite good. The theoretical profiles agree with the experimental profiles in both the thicker hydrodynamic region and in the thin film region which is under 100 nm. However, because the current limited magnification of the ISE hinders the exact location of a null point and the allocation of the exact position of the dark fringes is limited by the ability to accurately digitize and analyze the images, discrepancies between the modeling and the

  6. Effect of starvation on film thickness and traction under elastohydrodynamic rolling and sliding conditions

    NASA Technical Reports Server (NTRS)

    Wedeven, L. D.

    1975-01-01

    Traction measurements under starved elastohydrodynamic conditions were obtained for a point-contact geometry. Simultaneous measurements of the film thickness and the location of the inlet lubricant boundary were made. Optical interferometry was used to measure film thickness. The thickness of a starved film for combined rolling and sliding conditions varies with the location of the inlet boundary in the same way as previously found for pure rolling conditions. When the fluid velocity distribution is calculated in the inlet region by a Reynolds lubrication analysis, backflow is seen to occur over a portion of the inlet region. Backflow is essential for the establishment of a flooded condition. The location of certain fluid velocity conditions within the inlet region, as suggested in the literature, does not adequately describe the onset of starvation. For the same slide-roll ratio a starved film was observed to possess greater traction than a flooded film. Traction measurements under starved conditions were also compared with those under flooded conditions for equivalent shear rates in the Hertzian region. When the shear rates within the Hertzian region were low and the film was severely starved, the measured tractions were lower than expected. This may be due to large shear stresses developed by the large pressure gradients that are generated in the inlet region when it is severely starved.

  7. Thickness-Dependent Coherent Phonon Frequency in Ultrathin FeSe/SrTiO₃ Films.

    PubMed

    Yang, Shuolong; Sobota, Jonathan A; Leuenberger, Dominik; Kemper, Alexander F; Lee, James J; Schmitt, Felix T; Li, Wei; Moore, Rob G; Kirchmann, Patrick S; Shen, Zhi-Xun

    2015-06-10

    Ultrathin FeSe films grown on SrTiO3 substrates are a recent milestone in atomic material engineering due to their important role in understanding unconventional superconductivity in Fe-based materials. By using femtosecond time- and angle-resolved photoelectron spectroscopy, we study phonon frequencies in ultrathin FeSe/SrTiO3 films grown by molecular beam epitaxy. After optical excitation, we observe periodic modulations of the photoelectron spectrum as a function of pump-probe delay for 1-unit-cell, 3-unit-cell, and 60-unit-cell thick FeSe films. The frequencies of the coherent intensity oscillations increase from 5.00 ± 0.02 to 5.25 ± 0.02 THz with increasing film thickness. By comparing with previous works, we attribute this mode to the Se A1g phonon. The dominant mechanism for the phonon softening in 1-unit-cell thick FeSe films is a substrate-induced lattice strain. Our results demonstrate an abrupt phonon renormalization due to a lattice mismatch between the ultrathin film and the substrate. PMID:26027951

  8. Influence of Thickness on the Electrical Transport Properties of Exfoliated Bi2Te3 Ultrathin Films.

    PubMed

    Mo, D L; Wang, W B; Cai, Q

    2016-12-01

    In this work, the mechanical exfoliation method has been utilized to fabricate Bi2Te3 ultrathin films. The thickness of the ultrathin films is revealed to be several tens of nanometers. Weak antilocalization effects and Shubnikov de Haas oscillations have been observed in the magneto-transport measurements on individual films with different thickness, and the two-dimensional surface conduction plays a dominant role. The Fermi level is found to be 81 meV above the Dirac point, and the carrier mobility can reach ~6030 cm(2)/(Vs) for the 10-nm film. When the film thickness decreases from 30 to 10 nm, the Fermi level will move 8 meV far from the bulk valence band. The coefficient α in the Hikami-Larkin-Nagaoka equation is shown to be ~0.5, manifesting that only the bottom surface of the Bi2Te3 ultrathin films takes part in transport conductions. These will pave the way for understanding thoroughly the surface transport properties of topological insulators. PMID:27484860

  9. Influence of Thickness on the Electrical Transport Properties of Exfoliated Bi2Te3 Ultrathin Films

    NASA Astrophysics Data System (ADS)

    Mo, D. L.; Wang, W. B.; Cai, Q.

    2016-08-01

    In this work, the mechanical exfoliation method has been utilized to fabricate Bi2Te3 ultrathin films. The thickness of the ultrathin films is revealed to be several tens of nanometers. Weak antilocalization effects and Shubnikov de Haas oscillations have been observed in the magneto-transport measurements on individual films with different thickness, and the two-dimensional surface conduction plays a dominant role. The Fermi level is found to be 81 meV above the Dirac point, and the carrier mobility can reach ~6030 cm2/(Vs) for the 10-nm film. When the film thickness decreases from 30 to 10 nm, the Fermi level will move 8 meV far from the bulk valence band. The coefficient α in the Hikami-Larkin-Nagaoka equation is shown to be ~0.5, manifesting that only the bottom surface of the Bi2Te3 ultrathin films takes part in transport conductions. These will pave the way for understanding thoroughly the surface transport properties of topological insulators.

  10. Thickness effect on the structural and electrical properties of poly-SiGe films

    SciTech Connect

    Asafa, T.B.; Witvrouw, A.; Schneider, D.; Moussa, A.; Tabet, N.; Said, S.A.M.

    2014-01-01

    Graphical abstract: - Highlights: • Stress and Young's modulus of poly-SiGe film are linked to the grain columnar structure. • The above properties remain unchanged for poly-SiGe films thicker than 40 nm. • The point of transition is close to the electron mean free path for SiGe. • Both the resistivity and Hall mobility follow a similar trend. - Abstract: As lateral dimensions of electromechanical devices are scaled down to length scales comparable to electron mean free paths, the influence of thickness effect on their properties becomes sine qua non. This paper presents a detailed study of thickness effect on the Young's modulus, residual stress, resistivity and Hall mobility of ultrathin poly-Si{sub 11}Ge{sub 89} films deposited by low pressure chemical vapour deposition. The Young's moduli for the films thicker than ∼40 nm are close to the bulk value (135 GPa) while those of the thinner films are much lower. The reduction in resistivity and subsequent improved Hall mobility as thickness increases are discussed in light of surface morphology which is evident from atomic microscopy images. The near constant values of Young's modulus, resistivity and Hall mobility for the films thicker than ∼40 nm are attributed to the columnar grain structure as confirmed by the transmission electron microscopy images.

  11. Image processing techniques for measuring non-uniform film thickness profiles

    SciTech Connect

    Nitta, S.V.; Liu, An-Hong; Plawsky, J.L.; Wayner, P.C. Jr.

    1996-12-31

    The long term objective of this research program is to determine the fluid flow and drying characteristics of thin liquid/solid films using image processing techniques such as Image Analyzing Interferometry (IAI) and Image Scanning Ellipsometry (ISE). The primary purpose of this paper is to present experimental data on the effectiveness of IAI and ISE to measure nonuniform film thickness profiles. Steady-state, non-isothermal profiles of evaporating films were measured using IAI. Transient thickness profiles of a draining film were measured using ISE. The two techniques are then compared and contrasted. The ISE can be used to measure transient as well as steady-state profiles of films with thickness ranging from 1 nm to > 20 {mu}m, whereas IAI can be used to directly measure Steady-state and transient profiles of only films thicker than about 100 nm. An evaluation of the reflected intensity can be used to extend the use of the IAI below 100 nm.

  12. In situ method for real time measurement of dielectric film thickness in plasmas

    SciTech Connect

    Jang, Sung-Ho; Kim, Gun-Ho; Chung, Chin-Wook

    2010-01-15

    An in situ thickness measurement method of dielectric films (dual frequency method) was developed, and the thicknesses were measured in an inductively coupled plasma. This method uses a small ac bias voltage with two frequencies for thickness measurement. The dielectric thickness is obtained from measuring the amplitudes of the two frequency ac currents through a sensor, as well as using an equivalent circuit model describing impedance of the dielectric film and the plasma sheath. In the experiment, the thicknesses of Al{sub 2}O{sub 3} film could be accurately measured in real time. To check the measurement reliability, the dual frequency method was compared with reflection spectrophotometry as a technique for optical thickness diagnostics. It was found that the dual frequency method agrees closely with reflection spectrophotometry at various rf powers and pressures. In addition, this method is very simple and can be installed anywhere in plasma reactors, in contrast with optical methods; therefore, it is expected to be applied to in situ surface diagnostics for various processing plasmas.

  13. BAF(2) POST-DEPOSITION REACTION PROCESS FOR THICK YBCO FILMS.

    SciTech Connect

    SUENAGA,M.; SOLOVYOV,V.F.; WU,L.; WIESMANN,H.J.; ZHU,Y.

    2001-07-12

    The basic processes of the so-called BaF{sub 2} process for the formation of YBa{sub 2}Cu{sub 3}O{sub 7}, YBCO, films as well as its advantages over the in situ formation processes are discussed in the previous chapter. The process and the properties of YBCO films by this process were also nicely described in earlier articles by R. Feenstra, et al. Here, we will discuss two pertinent subjects related to fabrication of technologically viable YBCO conductors using this process. These are (1) the growth of thick (>> 1 {micro}m) c-axis-oriented YBCO films and (2) their growth rates. Before the detail discussions of these subjects are given, we first briefly discuss what geometrical structure a YBCO-coated conductor should be. Then, we will provide examples of simple arguments for how thick the YBCO films and how fast their growth rates need to be. Then, the discussions in the following two sections are devoted to: (1) the present understanding of the nucleation and the growth process for YBCO, and why it is so difficult to grow thick c-axis-oriented films (> 3 {micro}m), and (2) our present understanding of the YBCO growth-limiting mechanism and methods to increase the growth rates. The values of critical-current densities J{sub c} in these films are of primary importance for the applications,. and the above two subjects are intimately related to the control of J{sub c} of the films. In general, the lower the temperatures of the YBCO formation are the higher the values of J{sub c} of the films. Thus, the present discussion is limited to those films which are reacted at {approx}735 C. This is the lowest temperature at which c-axis-oriented YBCO films (1-3 {micro}m thick) are comfortably grown. It is also well known that the non-c-axis oriented YBCO platelets are extremely detrimental to the values of J{sub c} such that their effects on J{sub c} dwarf essentially all of other microstructural effects which control J{sub c}. Hence, the discussion given below is mainly

  14. Phase-field simulations of thickness-dependent domain stability in PbTiO3 thin films

    SciTech Connect

    Sheng, Guang; Hu, Jia-Mian; Zhang, Jinxian; Li, Yulan; Liu, Z. K.; Chen, Long-Qing

    2012-05-06

    Phase-field approach is used to predict the thickness effect on the domain stability in ferroelectric thin films. The strain relaxation mechanism and critical thickness for dislocation formation from both Matthews-Blakeslee (MB) and People-Bean (PB) models are employed. Thickness - strain domain stability diagrams are obtained for PbTiO3 thin films under different strain relaxation models. The relative domain fractions as a function of film thickness are also calculated and compared with experiment measurements in PbTiO3 thin films grown on SrTiO3 and KTaO3 substrates.

  15. Comparative study on the thickness-dependent properties of ITO and GZO thin films grown on glass and PET substrates

    NASA Astrophysics Data System (ADS)

    Kim, J. S.; Park, J.-K.; Baik, Y. J.; Kim, W. M.; Jeong, J.; Seong, T.-Y.

    2012-11-01

    The thickness-dependent properties of amorphous Sn-doped In2O3 (ITO) and polycrystalline Ga-doped ZnO (GZO) films grown on polyethylene terephthalate (PET) with a polymeric hard coating were compared with those deposited on Corning glass. The film thickness varied from 20 to 1310 nm. The electrical properties of the ITO films on PET were almost similar to those of the ITO films on glass. On the other hand, GZO films showed slightly poorer electrical properties when deposited on PET, but the difference was marginal. The electrical properties of amorphous ITO films were independent of film thickness, but polycrystalline GZO films exhibited monotonicallyimproving behavior with increasing thickness, mainly due to enhanced crystallinity and increased grain size with increasing film thickness. Although the air-referenced transmittance spectra of films on PET were about 2-3% lower than those on glass due to the lower transmittance of PET, the substrate-referenced optical transmittances of films on PET were higher than those on glass, reflecting the somewhat coarse structure of films on PET. Both the ITO and the GZO films on PET with a polymeric hard coating were shown to yield properties comparable to those oof both films on glass.

  16. Development of X-Shape Filtered Arc Deposition Apparatus for Thick ta-C Film Coating

    NASA Astrophysics Data System (ADS)

    Hikokasa, Hiroki; Iwasaki, Yasuhiro; Takikawa, Hirofumi; Sakakibara, Tateki; Hasegawa, Hiroshi; Tsuji, Nobuhiro

    Novel X-shape filtered arc deposition (X-FAD) apparatus is specially designed and newly developed for thick hydrogen-free tetrahedral amorphous-carbon (ta-C) film coating on superhard alloy (or cemented carbide) substrate. The apparatus has a graphite cathode for deposition of hydrogen-free diamond-like carbon (DLC; ta-C and amorphous carbon: a-C) film and a chromium (Cr) cathode for deposition of Cr layer. The filter duct shapes a composed form of a T-shape filter (T-FAD) for DLC film and a crank-shape filter (Crank FAD) for Cr film. Both carbon plasma beam and Cr plasma beam finally pass through a common plasma duct and scanner part, and go forward to the substrate. It is known that the adhesion of ta-C film to the superhard alloy is not good and the employment of binding interlayer between ta-C film and superhard alloy is one of the solutions. In this paper, using X-FAD, thick ta-C film was prepared on the superhard alloy. Principal results were as follows. (1) Crank FAD remarkably worked to prepare droplet-free Cr film. (2) Cr single layer did not work as appropriate biding interlayer between superhard alloy and ta-C. (3) Multi interlayer composed of Cr, a-C, and functionally graded DLC (a-C to ta-C), worked as a good biding interlayer for ta-C film on superhard alloy with thickness of more than 1 μm.

  17. Growth of ultrathin ZrO2 films on Si (100): Film-thickness-dependent band alignment

    NASA Astrophysics Data System (ADS)

    Sandell, A.; Karlsson, P. G.; Richter, J. H.; Blomquist, J.; Uvdal, P.; Grehk, T. M.

    2006-03-01

    The band alignment of ultrathin ZrO2 films of different thickness formed on Si (100) have been monitored with synchrotron radiation photoelectron spectroscopy and x-ray absorption spectroscopy. The films were deposited sequentially by way of metal-organic chemical-vapor deposition in ultrahigh vacuum. A significant decrease in the conduction band offset is found for increasing film thickness. It is accompanied by a corresponding increase of the valence band offset. The variations originate in the formation of an interfacial layer characterized by a lower degree of Zr-O interaction than in bulk ZrO2 but with no clear evidence for partially occupied Zr4d dangling bonds.

  18. Determining the refractive index and thickness of thin films from prism coupler measurements

    NASA Technical Reports Server (NTRS)

    Kirsch, S. T.

    1981-01-01

    A simple method of determining thin film parameters from mode indices measured using a prism coupler is described. The problem is reduced to doing two least squares straight line fits through measured mode indices vs effective mode number. The slope and y intercept of the line are simply related to the thickness and refractive index of film, respectively. The approach takes into account the correlation between as well as the uncertainty in the individual measurements from all sources of error to give precise error tolerances on the best fit values. Due to the precision of the tolerances, anisotropic films can be identified and characterized.

  19. Effect of alkane chain length and counterion on the freezing transition of cationic surfactant adsorbed film at alkane mixture - water interfaces.

    PubMed

    Tokiwa, Yuhei; Sakamoto, Hiroyasu; Takiue, Takanori; Aratono, Makoto; Matsubara, Hiroki

    2015-05-21

    Penetration of alkane molecules into the adsorbed film gives rise to a surface freezing transition of cationic surfactant at the alkane-water interface. To examine the effect of the alkane chain length and counterion on the surface freezing, we employed interfacial tensiometry and ellipsometry to study the interface of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride aqueous solutions against dodecane, tetradecane, hexadecane, and their mixtures. Applying theoretical equations to the experimental results obtained, we found that the alkane molecules that have the same chain length as the surfactant adsorb preferentially into the surface freezing film. Furthermore, we demonstrated that the freezing transition temperature of cationic surfactant adsorbed film was independent of the kind of counterion. PMID:25932500

  20. Structural, electrical and magnetic properties of evaporated permalloy thin films: effect of substrate and thickness

    NASA Astrophysics Data System (ADS)

    Guittoum, A.; Bourzami, A.; Layadi, A.; Schmerber, G.

    2012-05-01

    We have studied the effects of the substrate and the thickness on the structural, electrical and magnetic properties of permalloy thin films Ni81Fe19 (Py). Series of Py thin films were evaporated on four various substrates: glass, kapton, Si(1 0 0) and Si(1 1 1). The thickness ranges from 13 nm to 190 nm. We show that evaporated permalloy on kapton and Si(1 1 1) present a strong ⟨1 1 1⟩ preferred orientation for samples thicker than 85 nm; however, the films grown on glass and Si(1 0 0) present a weak (1 1 1) texture for most of these samples. Generally, the lattice constant for Py/glass, Py/Si(1 0 0) and Py/Si(1 1 1) samples is found to be smaller than the bulk value (abulk), while for the Py/kapton, it is larger than abulk. There is an overall increase of the grain sizes (100 Å-480 Å) with thickness for Py/Si(1 1 1), Py/Si(1 0 0) and Py/glass. For the Py/kapton samples, the grain sizes (about 130 Å) seem to be independent of the thickness. The resistivity, ρ, decreases with increasing thickness for all samples. The highest values of ρ were observed in the Py/kapton thin films, diffusion at the grain boundaries might be in part responsible for these high values. The magnetization easy axis is found to be in the film plane for all samples. For all series, the two thinner films seem to exhibit a perpendicular magnetocrystalline anisotropy. The coercive field, HC//, values range from 1 Oe to 67 Oe. A peak in the HC// vs. t curve is observed for Py/Si while for Py on glass and Py/kapton, HC// seems to be constant. We also observed that for the thicker Py/Si(1 1 1) samples, the coercivity decreases as the grain sizes increase.

  1. Thickness dependence of dielectric loss in SrTiO3 thin films

    NASA Astrophysics Data System (ADS)

    Li, Hong-Cheng; Si, Weidong; West, Alexander D.; Xi, X. X.

    1998-07-01

    We have measured the dielectric loss in SrTiO3 thin films grown on SrRuO3 electrode layers with thickness ranging from 25 nm to 2.5 μm. The loss depends strongly on the thickness but differently above and below T≈80 K: as the thickness increases, the loss decreases at high temperatures but becomes higher at low temperatures. Our result suggests that, in the high temperature regime, the interfacial dead layer effect dominates while, in the low temperature regime, the losses related to the structural phase transition and quantum fluctuations are important.

  2. Thickness-Dependent Structural and Optoelectronic Properties of In2O3 Films Prepared by Spray Pyrolysis Technique

    NASA Astrophysics Data System (ADS)

    Khan, M. A. Majeed; Khan, Wasi

    2016-08-01

    In this work, nanostructured In2O3 thin films with thickness in the range of 40-160 nm were deposited on glass substrates by the chemical spray pyrolysis technique. The microstructural, surface morphology and optical properties were investigated as a function of film thickness through x-ray diffraction, scanning electron microscopy equipped with energy dispersive spectroscopy, atomic force microscopy, Raman spectroscopy, UV-visible spectroscopy and photoluminescence measurements. The x-ray diffraction analysis showed that the deposited films were polycrystalline in nature with a cubic structure having (222) as preferred orientation. The morphological analyses of the samples exhibited uniform and smooth surface of the films with systematical increments in the surface roughness with increasing film thickness. The grain size increased from 9 nm to 13 nm with increasing film thickness. Raman spectroscopy has been employed to study the crystalline quality and the structural disorder of the films. A blue-shift in the energy band gap ( E g) from 3.74 eV to 3.98 eV was observed with the increase of film thickness. Moreover, photoluminescence peaks of the In2O3 films appeared at 443 nm and 527 nm for all films. The thickness had a substantial influence on the microstructural and optical properties as well as on the luminescence intensity of the films. The strategy presented here indicates that the prepared films could be suitable candidates for optoelectronic device applications.

  3. Thickness-Dependent Structural and Optoelectronic Properties of In2O3 Films Prepared by Spray Pyrolysis Technique

    NASA Astrophysics Data System (ADS)

    Khan, M. A. Majeed; Khan, Wasi

    2016-05-01

    In this work, nanostructured In2O3 thin films with thickness in the range of 40-160 nm were deposited on glass substrates by the chemical spray pyrolysis technique. The microstructural, surface morphology and optical properties were investigated as a function of film thickness through x-ray diffraction, scanning electron microscopy equipped with energy dispersive spectroscopy, atomic force microscopy, Raman spectroscopy, UV-visible spectroscopy and photoluminescence measurements. The x-ray diffraction analysis showed that the deposited films were polycrystalline in nature with a cubic structure having (222) as preferred orientation. The morphological analyses of the samples exhibited uniform and smooth surface of the films with systematical increments in the surface roughness with increasing film thickness. The grain size increased from 9 nm to 13 nm with increasing film thickness. Raman spectroscopy has been employed to study the crystalline quality and the structural disorder of the films. A blue-shift in the energy band gap (E g) from 3.74 eV to 3.98 eV was observed with the increase of film thickness. Moreover, photoluminescence peaks of the In2O3 films appeared at 443 nm and 527 nm for all films. The thickness had a substantial influence on the microstructural and optical properties as well as on the luminescence intensity of the films. The strategy presented here indicates that the prepared films could be suitable candidates for optoelectronic device applications.

  4. Variable Thickness Liquid Crystal Films for High Repetition Rate Laser Applications

    NASA Astrophysics Data System (ADS)

    Poole, Patrick; Willis, Christopher; Cochran, Ginevra; Hanna, Randall; Andereck, C. David; Schumacher, Douglass

    2015-05-01

    The presentation of a clean target or target substrate at high repetition rates is of importance to a number of photoelectron spectroscopy and free electron laser applications, often in high vacuum environments. Additionally, high intensity laser facilities are approaching the 10 Hz shot rate at petawatt powers, but are currently unable to insert targets at these rates. We have developed liquid crystal films to address this need for high rep rate targets while preserving the planar geometry advantageous to many applications. The molecular ordering of liquid crystal is variable with temperature and can be manipulated to form a layered thin film. In this way temperature and volume control can be used to vary film thickness in vacuo and on-demand between 10 nm and over 10 μm. These techniques were previously applied to a single-shot ion acceleration experiment in, where target thickness critically determines the physics of the acceleration. Here we present an automatic film formation device that utilizes a linear sliding rail to form liquid crystal films within the aforementioned range at rates up to 0.1 Hz. The design ensures film formation location within 2 μm RMS, well within the Rayleigh range of even short f-number systems. Details of liquid crystal films and this target formation device will be shown as well as recent experimental data from the Scarlet laser facility at OSU. This work was supported by DARPA through a grant from AMRDEC.

  5. Combined optical and acoustical method for determination of thickness and porosity of transparent organic layers below the ultra-thin film limit

    NASA Astrophysics Data System (ADS)

    Rodenhausen, K. B.; Kasputis, T.; Pannier, A. K.; Gerasimov, J. Y.; Lai, R. Y.; Solinsky, M.; Tiwald, T. E.; Wang, H.; Sarkar, A.; Hofmann, T.; Ianno, N.; Schubert, M.

    2011-10-01

    Analysis techniques are needed to determine the quantity and structure of materials composing an organic layer that is below an ultra-thin film limit and in a liquid environment. Neither optical nor acoustical techniques can independently distinguish between thickness and porosity of ultra-thin films due to parameter correlation. A combined optical and acoustical approach yields sufficient information to determine both thickness and porosity. We describe application of the combinatorial approach to measure single or multiple organic layers when the total layer thickness is small compared to the wavelength of the probing light. The instrumental setup allows for simultaneous in situ spectroscopic ellipsometry and quartz crystal microbalance dynamic measurements, and it is combined with a multiple-inlet fluid control system for different liquid solutions to be introduced during experiments. A virtual separation approach is implemented into our analysis scheme, differentiated by whether or not the organic adsorbate and liquid ambient densities are equal. The analysis scheme requires that the film be assumed transparent and rigid (non-viscoelastic). We present and discuss applications of our approach to studies of organic surfactant adsorption, self-assembled monolayer chemisorption, and multiple-layer target DNA sensor preparation and performance testing.

  6. Combined optical and acoustical method for determination of thickness and porosity of transparent organic layers below the ultra-thin film limit.

    PubMed

    Rodenhausen, K B; Kasputis, T; Pannier, A K; Gerasimov, J Y; Lai, R Y; Solinsky, M; Tiwald, T E; Wang, H; Sarkar, A; Hofmann, T; Ianno, N; Schubert, M

    2011-10-01

    Analysis techniques are needed to determine the quantity and structure of materials composing an organic layer that is below an ultra-thin film limit and in a liquid environment. Neither optical nor acoustical techniques can independently distinguish between thickness and porosity of ultra-thin films due to parameter correlation. A combined optical and acoustical approach yields sufficient information to determine both thickness and porosity. We describe application of the combinatorial approach to measure single or multiple organic layers when the total layer thickness is small compared to the wavelength of the probing light. The instrumental setup allows for simultaneous in situ spectroscopic ellipsometry and quartz crystal microbalance dynamic measurements, and it is combined with a multiple-inlet fluid control system for different liquid solutions to be introduced during experiments. A virtual separation approach is implemented into our analysis scheme, differentiated by whether or not the organic adsorbate and liquid ambient densities are equal. The analysis scheme requires that the film be assumed transparent and rigid (non-viscoelastic). We present and discuss applications of our approach to studies of organic surfactant adsorption, self-assembled monolayer chemisorption, and multiple-layer target DNA sensor preparation and performance testing. PMID:22047284

  7. Optical and electrical characterizations of nanocomposite film of titania adsorbed onto oxidized multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Feng, Yiyu; Wu, Zigang; Fujii, Akihiko; Ozaki, Masanori; Yoshino, Katsumi

    2005-07-01

    Composite film containing titania electrostatically linked to oxidized multiwalled carbon nanotubes (TiO2-s-MWNTs) was prepared from a suspension of TiO2 nanoparticles in soluble carbon nanotubes. The structure of the film was analysed principally by Fourier transform infrared spectroscopy, scanning electron micrography and x-ray diffraction. The optical and electrical characterizations of the film were investigated by UV-vis spectrum, photoluminescence and photoconductivity. The enhancement of photocurrent in the TiO2-s-MWNT film is discussed by taking the photoinduced charge transfer between the MWNT and TiO2 into consideration.

  8. Amorphous/microcrystalline transition of thick silicon film deposited by PECVD

    NASA Astrophysics Data System (ADS)

    Elarbi, N.; Jemaï, R.; Outzourhit, A.; Khirouni, K.

    2016-06-01

    Thick silicon films were deposited by plasma-enhanced chemical vapor deposition at different plasma power densities. Annealing treatment was performed on these deposited films. As-deposited and annealed films were characterized by X-ray diffraction, Raman scattering spectroscopy and reflectance spectroscopy. Before annealing, only the film deposited at the plasma power density of 500 mW/cm2 exhibits a diffraction peak corresponding to the (111) plane orientation. Raman spectrum of this film confirms the presence of crystalline phase. After annealing, a transition from amorphous phase to crystalline one occurs for all samples. This transition is accompanied by an increase of the crystalline fraction volume deduced from Raman spectra analysis and by a reduction of optical gap energy.

  9. Effect of film thickness on the magneto-structural properties of ion beam sputtered transition metal–metalloid FeCoNbB/Si (100) alloy thin films

    NASA Astrophysics Data System (ADS)

    Gupta, Pooja; Tripathi, Yagyanidhi; Kumar, Dileep; Rai, S. K.; Gupta, Mukul; Reddy, V. R.; Svec, Peter

    2016-08-01

    The structure and magnetic properties of ion beam sputtered transition metal–metalloid FeCoNbB/Si(100) alloy thin film have been studied as a function of film thickness using complementary techniques of x-ray reflectivity (XRR), grazing incidence x-ray diffraction, and magneto optical Kerr effect. Thicknesses of the films range from ∼200 to 1500 Å. The coercivity of all the films ranges between 4 and 14 Oe, which suggests soft magnetic nature of FeCoNbB/Si thin films. Films with thickness up to 800 Å are amorphous in nature and are found to possess uniaxial magnetic anisotropy in the film plane, although no magnetic field was applied during deposition. The presence of the two fold symmetry in such amorphous thin films may be attributed to quenched-in stresses developed during deposition. Upon increasing the film thickness to ∼1200 Å and above, the structure of FeCoNbB films transforms from amorphous to partially nanocrystalline structure and has bcc-FeCo nanocrystalline phase dispersed in remaining amorphous matrix. The crystalline volume fraction (cvf) of the films is found to be proportional to the film thickness. Azimuthal angle dependence of remanence confirms the presence of in-plane four-fold anisotropy (FFA) in the crystalline film with cvf ∼75%. Synchrotron x-ray diffraction measurement using area detector suggests random orientation of crystallites and thus clearly establishes that FFA is not related to texture/cubic symmetry in such polycrystalline thin films. As supported by asymmetric Bragg diffraction measurements, the origin of FFA in such partially crystalline thin film is ascribed to the additional compressive stresses developed in the film upon crystallization. Results indicate that promising soft magnetic properties in such films can be optimized by controlling the film thickness. The revelation of controllable and tunable anisotropy suggests that FeCoNbB thin films can have potential application in electromagnetic applications.

  10. Full-field optical thickness profilometry of semitransparent thin films with transmission densitometry

    SciTech Connect

    Johnson, Jay; Harris, Tequila

    2010-05-20

    A novel bidirectional thickness profilometer based on transmission densitometry was designed to measure the localized thickness of semitransparent films on a dynamic manufacturing line. The densitometer model shows that, for materials with extinction coefficients between 0.3 and 2.9 D/mm, 100-500 {mu}m measurements can be recorded with less than {+-}5% error at more than 10,000 locations in real time. As a demonstration application, the thickness profiles of 75 mmx100 mm regions of polymer electrolyte membrane (PEM) were determined by converting the optical density of the sample to thickness with the Beer-Lambert law. The PEM extinction coefficient was determined to be 1.4 D/mm, with an average thickness error of 4.7%.

  11. Retention of Root Canal Posts: Effect of Cement Film Thickness, Luting Cement, and Post Pretreatment.

    PubMed

    Sahafi, A; Benetti, A R; Flury, S; Peutzfeldt, A

    2015-01-01

    The aim of this study was to investigate the effect of the cement film thickness of a zinc phosphate or a resin cement on retention of untreated and pretreated root canal posts. Prefabricated zirconia posts (CosmoPost: 1.4 mm) and two types of luting cements (a zinc phosphate cement [DeTrey Zinc] and a self-etch adhesive resin cement [Panavia F2.0]) were used. After removal of the crowns of 360 extracted premolars, canines, or incisors, the root canals were prepared with a parallel-sided drill system to three different final diameters. Half the posts did not receive any pretreatment. The other half received tribochemical silicate coating according to the manufacturer's instructions. Posts were then luted in the prepared root canals (n=30 per group). Following water storage at 37°C for seven days, retention of the posts was determined by the pull-out method. Irrespective of the luting cement, pretreatment with tribochemical silicate coating significantly increased retention of the posts. Increased cement film thickness resulted in decreased retention of untreated posts and of pretreated posts luted with zinc phosphate cement. Increased cement film thickness had no influence on retention of pretreated posts luted with resin cement. Thus, retention of the posts was influenced by the type of luting cement, by the cement film thickness, and by the post pretreatment. PMID:25764045

  12. Thickness-Gradient Films for High Gauge Factor Stretchable Strain Sensors.

    PubMed

    Liu, Zhiyuan; Qi, Dianpeng; Guo, Peizhi; Liu, Yan; Zhu, Bowen; Yang, Hui; Liu, Yaqing; Li, Bin; Zhang, Chenguang; Yu, Jiancan; Liedberg, Bo; Chen, Xiaodong

    2015-10-28

    High-gauge-factor stretchable strain sensors are developed by utilizing a new strategy of thickness-gradient films with high durability, and high uniaxial/isotropic stretchability based on the self-pinning effect of SWCNTs. The monitoring of detailed damping vibration modes driven by weak sound based on such sensors is demonstrated, making a solid step toward real applications. PMID:26376000

  13. CO responses of sensors based on cerium oxide thick films prepared from clustered spherical nanoparticles.

    PubMed

    Izu, Noriya; Matsubara, Ichiro; Itoh, Toshio; Akamatsu, Takafumi; Shin, Woosuck

    2013-01-01

    Various types of CO sensors based on cerium oxide (ceria) have been reported recently. It has also been reported that the response speed of CO sensors fabricated from porous ceria thick films comprising nanoparticles is extremely high. However, the response value of such sensors is not suitably high. In this study, we investigated methods of improving the response values of CO sensors based on ceria and prepared gas sensors from core-shell ceria polymer hybrid nanoparticles. These hybrid nanoparticles have been reported to have a unique structure: The core consists of a cluster of ceria crystallites several nanometers in size. We compared the characteristics of the sensors based on thick films prepared from core-shell nanoparticles with those of sensors based on thick films prepared from conventionally used precipitated nanoparticles. The sensors prepared from the core-shell nanoparticles exhibited a resistance that was ten times greater than that of the sensors prepared from the precipitated nanoparticles. The response values of the gas sensors based on the core-shell nanoparticles also was higher than that of the sensors based on the precipitated nanoparticles. Finally, improvements in sensor response were also noticed after the addition of Au nanoparticles to the thick films used to fabricate the two types of sensors. PMID:23529123

  14. Computerized J-H loop tracer for soft magnetic thick films in the audio frequency range

    NASA Astrophysics Data System (ADS)

    Loizos, G.; Niarchos, D.

    2014-07-01

    A computerized J-H loop tracer for soft magnetic thick films in the audio frequency range is described. It is a system built on a PXI platform combining PXI modules for control signal generation and data acquisition. The physiscal signals are digitized and the respective data strems are processed, presented and recorded in LabVIEW 7.0.

  15. Laser-printed/structured thick-film electrodes for Li-ion microbatteries

    NASA Astrophysics Data System (ADS)

    Kim, Heungsoo; Sutto, Thomas E.; Proell, Johannes; Kohler, Robert; Pfleging, Wilhelm; Piqué, Alberto

    2014-03-01

    Laser induced forward transfer (LIFT) process was used to print thick-film electrodes (LiCoO2 cathode and carbon anode) and solid-state polymer membranes for Li-ion microbatteries. Their electrochemical behaviors were characterized by cyclic voltammograms, capacity measurement and cycling performance. Microbatteries based on these laser-printed thick-film electrodes showed significantly higher discharge capacities than those made by sputter-deposited thin film techniques. This enhanced performance is attributed to the high surface area porous structure of the laser-printed electrodes that allows improved diffusion of the Li-ions across the 100 μm-thick electrodes without a significant internal resistance. In addition, a laser structuring process was used to prepare three-dimensional microstructures on the laserprinted thick-film electrodes to further improve battery performance by increasing the active surface area. These results indicate that the laser processing techniques are a viable approach for developing Li-ion microbatteries in microelectronic devices. This paper will show examples of Li-ion microbatteries fabricated with various polymer separators and structured electrodes using a combination of LIFT and excimer laser structuring processes.

  16. Method and system using power modulation and velocity modulation producing sputtered thin films with sub-angstrom thickness uniformity or custom thickness gradients

    DOEpatents

    Montcalm, Claude; Folta, James Allen; Walton, Christopher Charles

    2003-12-23

    A method and system for determining a source flux modulation recipe for achieving a selected thickness profile of a film to be deposited (e.g., with highly uniform or highly accurate custom graded thickness) over a flat or curved substrate (such as concave or convex optics) by exposing the substrate to a vapor deposition source operated with time-varying flux distribution as a function of time. Preferably, the source is operated with time-varying power applied thereto during each sweep of the substrate to achieve the time-varying flux distribution as a function of time. Preferably, the method includes the steps of measuring the source flux distribution (using a test piece held stationary while exposed to the source with the source operated at each of a number of different applied power levels), calculating a set of predicted film thickness profiles, each film thickness profile assuming the measured flux distribution and a different one of a set of source flux modulation recipes, and determining from the predicted film thickness profiles a source flux modulation recipe which is adequate to achieve a predetermined thickness profile. Aspects of the invention include a computer-implemented method employing a graphical user interface to facilitate convenient selection of an optimal or nearly optimal source flux modulation recipe to achieve a desired thickness profile on a substrate. The method enables precise modulation of the deposition flux to which a substrate is exposed to provide a desired coating thickness distribution.

  17. Effects of Au source/drain thickness on electrical characteristics of pentacene thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kwon, Jin-Hyuk; Hahn, Joonku; Bae, Jin-Hyuk; Ham, Youngjin; Park, Jaehoon; Baang, Sungkeun

    2015-11-01

    We investigate the electrical characteristics of top-contact pentacene thin-film transistors (TFTs) fabricated with various thicknesses of the Au source and the drain (S/D) electrodes, i.e., 20, 30, 50, 70, and 105 nm. Pentacene TFTs exhibit enhancements in the drain current and the fieldeffect mobility with increasing thickness of Au S/D electrodes up to 50 nm, after which the TFT performance degrades with increasing Au thickness. A transmission line method is used to analyze the contact resistance between the Au electrode and the pentacene layer in the TFTs, and ultraviolet photoemission spectroscopy measurements are performed to determine the work function of the Au films. The lowest contact resistance, 73 kΩ·cm, is obtained for the 50-nm-thick Au case and is ascribed to the high work function (4.67 eV) of the film. Consequently, the effects of the Au S/D thickness on the performance of top-contact pentacene TFTs can be understood through the behavior of the charge injection at the Au electrode/pentacene interface.

  18. 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.

  19. Magnetic relaxation due to spin pumping in thick ferromagnetic films in contact with normal metals

    NASA Astrophysics Data System (ADS)

    Rezende, S. M.; Rodríguez-Suárez, R. L.; Azevedo, A.

    2013-07-01

    Spin pumping is the most important magnetic relaxation channel in ultrathin ferromagnetic layers in contact with normal metals (NMs). Recent experiments indicate that in thick films of insulating yttrium iron garnet (YIG) there is a large broadening of the ferromagnetic resonance (FMR) lines with deposition of a thin Pt layer which cannot be explained by the known damping processes. Here we present a detailed study of the magnetic relaxation due to spin pumping in bilayers made of a ferromagnetic material (FM) and a NM. Two alternative approaches are used to calculate the transverse and longitudinal relaxation rates used in the Bloch-Bloembergen formulation of damping. In one we consider that the dynamic exchange coupling at the interface transfers magnetic relaxation from the heavily damped conduction electron spins in the NM layer to the magnetization of the FM layer while the other utilizes spin currents and the concept of the spin-mixing conductance at the interface. While in thin FM films, the relaxation rates vary with the inverse of the FM layer thickness; in thick films, they become independent of the thickness because in the FM/NM structure the FMR excitation has a surface mode character. Regardless of the thickness range the longitudinal relaxation rate is twice the transverse rate resulting in damping of the magnetization with constant amplitude characterizing a Gilbert process. The enhanced spin-pumping damping explains the experimental observations in YIG/Pt bilayers.

  20. Method for rapid, controllable growth and thickness, of epitaxial silicon films

    DOEpatents

    Wang, Qi; Stradins, Paul; Teplin, Charles; Branz, Howard M.

    2009-10-13

    A method of producing epitaxial silicon films on a c-Si wafer substrate using hot wire chemical vapor deposition by controlling the rate of silicon deposition in a temperature range that spans the transition from a monohydride to a hydrogen free silicon surface in a vacuum, to obtain phase-pure epitaxial silicon film of increased thickness is disclosed. The method includes placing a c-Si substrate in a HWCVD reactor chamber. The method also includes supplying a gas containing silicon at a sufficient rate into the reaction chamber to interact with the substrate to deposit a layer containing silicon thereon at a predefined growth rate to obtain phase-pure epitaxial silicon film of increased thickness.

  1. Measurement of oil film thickness for application to elastomeric Stirling engine rod seals

    NASA Technical Reports Server (NTRS)

    Krauter, A. I.

    1981-01-01

    The rod seal in the Stirling engine has the function of separating high pressure gas from low or ambient pressure oil. An experimental apparatus was designed to measure the oil film thickness distribution for an elastomeric seal in a reciprocating application. Tests were conducted on commercial elastomeric seals having a 76 mm rod and a 3.8 mm axial width. Test conditions included 70 and 90 seal durometers, a sliding velocity of 0.8 m/sec, and a zero pressure gradient across the seal. An acrylic cylinder and a typical synthetic base automotive lubricant were used. The experimental results showed that the effect of seal hardness on the oil film thickness is considerable. A comparison between analytical and experimental oil film profiles for an elastomeric seal during relatively high speed reciprocating motion showed an overall qualitative agreement.

  2. Observation of three crystalline layers in hydrothermally grown BiFeO{sub 3} thick films

    SciTech Connect

    Lee, T. K.; Sung, K. D.; Jung, J. H.; Kim, T. H.; Ko, J.-H.

    2014-11-21

    We report the observation of three different crystalline layers in hydrothermally grown BiFeO{sub 3} (BFO) thick films on SrRuO{sub 3}/SrTiO{sub 3} substrates. High-resolution X-ray diffraction and transmission electron microcopy results suggest that compressively strained, partially relaxed epitaxial layers, and a mixture of polycrystalline and amorphous BFO layers, were successively formed from the bottom to the top of the films. The resistance and capacitance of the mixed layer were significantly lower than those of the epitaxial layers. The atomic concentrations of Bi and Fe in the mixed layer were fluctuating for each point. Based on the observed three crystalline layers, we have discussed the growth mechanism and the leakage current of hydrothermally grown BFO thick films.

  3. Cellular-foam polypropylene ferroelectrets with increased film thickness and reduced resonance frequency

    NASA Astrophysics Data System (ADS)

    Sborikas, Martynas; Wegener, Michael

    2013-12-01

    Ferroelectrets are piezoelectric materials suitable for acoustic applications such as airborne ultrasonic transducers. Typical ferroelectrets exhibit resonance frequencies in the high kHz to low MHz range. In order to decrease the transducer resonance frequencies to the low kHz range, processes such as gas-diffusion expansion and electric charging were adjusted to cellular films which are initially twice as thick as in earlier studies. The demonstrated film expansion and electric charging lead to mechanically soft cellular structures which show high piezoelectric activities with coefficients up to 130 pC/N. Due to the simultaneously increased film thicknesses, the resonance frequencies are lowered down to about 233 kHz.

  4. Hard X-rays for processing hybrid organic-inorganic thick films.

    PubMed

    Jiang, Yu; Carboni, Davide; Pinna, Alessandra; Marmiroli, Benedetta; Malfatti, Luca; Innocenzi, Plinio

    2016-01-01

    Hard X-rays, deriving from a synchrotron light source, have been used as an effective tool for processing hybrid organic-inorganic films and thick coatings up to several micrometres. These coatings could be directly modified, in terms of composition and properties, by controlled exposure to X-rays. The physico-chemical properties of the coatings, such as hardness, refractive index and fluorescence, can be properly tuned using the interaction of hard X-rays with the sol-gel hybrid films. The changes in the microstructure have been correlated especially with the modification of the optical and the mechanical properties. A relationship between the degradation rate of the organic groups and the rise of fluorescence from the hybrid material has been observed; nanoindentation analysis of the coatings as a function of the X-ray doses has shown a not linear dependence between thickness and film hardness. PMID:26698073

  5. Fabrication of 5-20 nm thick β-W films

    SciTech Connect

    Narasimham, Avyaya J.; Medikonda, Manasa; Matsubayashi, Akitomo; Khare, Prasanna; Chong, Hyuncher; Matyi, Richard J.; Diebold, Alain; LaBella, Vincent P.

    2014-11-15

    A technique to fabricate 5 to 20 nm thick sputter deposited β W films on SiO{sub 2} and Si substrates is presented. This is achieved by growing tungsten on a 5 nm SiO{sub 2} layer or in an oxygen controlled environment by flowing 2 sccm of O{sub 2} during deposition. Resistivity, X-ray photoelectron spectroscopy, X-ray diffraction and reflectivity studies were performed to determine the phase and thickness of tungsten films. These results demonstrate a technique to grow this film on bare Si or a SiO{sub 2} substrate, which can enable growth on the bottom of a write unit in a non-volatile spin logic device.

  6. Systems Issues Pertaining to Holographic Optical Data Storage in Thick Bacteriorhodopsin Films

    NASA Technical Reports Server (NTRS)

    Downie, John D.; Timucin, Dogan A.; Gary, Charles K.; Oezcan, Meric; Smithey, Daniel T.; Crew, Marshall; Lau, Sonie (Technical Monitor)

    1998-01-01

    The optical data storage capacity and raw bit-error-rate achievable with thick photochromic bacteriorhodopsin (BR) films are investigated for sequential recording and read- out of angularly- and shift-multiplexed digital holograms inside a thick blue-membrane D85N BR film. We address the determination of an exposure schedule that produces equal diffraction efficiencies among each of the multiplexed holograms. This exposure schedule is determined by numerical simulations of the holographic recording process within the BR material, and maximizes the total grating strength. We also experimentally measure the shift selectivity and compare the results to theoretical predictions. Finally, we evaluate the bit-error-rate of a single hologram, and of multiple holograms stored within the film.

  7. Real-time dielectric-film thickness measurement system for plasma processing chamber wall monitoring

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Yong; Chung, Chin-Wook

    2015-12-01

    An in-situ real-time processing chamber wall monitoring system was developed. In order to measure the thickness of the dielectric film, two frequencies of small sinusoidal voltage (˜1 V) signals were applied to an electrically floated planar type probe, which is positioned at chamber wall surface, and the amplitudes of the currents and the phase differences between the voltage and current were measured. By using an equivalent sheath circuit model including a sheath capacitance, the dielectric thickness can be obtained. Experiments were performed in various plasma condition, and reliable dielectric film thickness was obtained regardless of the plasma properties. In addition, availability in commercial chamber for plasma enhanced chemical vapor deposition was verified. This study is expected to contribute to the control of etching and deposition processes and optimization of periodic maintenance in semiconductor manufacturing process.

  8. Analysis of variance on thickness and electrical conductivity measurements of carbon nanotube thin films

    NASA Astrophysics Data System (ADS)

    Li, Min-Yang; Yang, Mingchia; Vargas, Emily; Neff, Kyle; Vanli, Arda; Liang, Richard

    2016-09-01

    One of the major challenges towards controlling the transfer of electrical and mechanical properties of nanotubes into nanocomposites is the lack of adequate measurement systems to quantify the variations in bulk properties while the nanotubes were used as the reinforcement material. In this study, we conducted one-way analysis of variance (ANOVA) on thickness and conductivity measurements. By analyzing the data collected from both experienced and inexperienced operators, we found some operation details users might overlook that resulted in variations, since conductivity measurements of CNT thin films are very sensitive to thickness measurements. In addition, we demonstrated how issues in measurements damaged samples and limited the number of replications resulting in large variations in the electrical conductivity measurement results. Based on this study, we proposed a faster, more reliable approach to measure the thickness of CNT thin films that operators can follow to make these measurement processes less dependent on operator skills.

  9. Measurement of film thickness up to several hundreds of nanometers using optical waveguide lightmode spectroscopy.

    PubMed

    Picart, Catherine; Gergely, Csilla; Arntz, Youri; Voegel, Jean-Claude; Schaaf, Pierre; Cuisinier, Frédéric J G; Senger, Bernard

    2004-10-15

    Up to now, most studies based on optical waveguide lightmode spectroscopy (OWLS) were dedicated to thin adlayers, assumed to be isotropic and homogeneous, for which data analysis was based on an approximation of the mode equations valid when the thickness is small with respect to the wavelength of the laser light. The aim of the present paper is to extend the use of OWLS to thicker deposited layers (up to approximately 400 nm). Both the simplified and extended models are compared in terms of optical parameters, i.e. the refractive index nA, the thickness dA, and the optical mass QA, for experimental data obtained with polyelectrolyte multilayer films. The deviation of these parameters can be quite large when derived using the simplified model instead of the extended model. This observation evidences that OWLS is well suited for the study of "thick" films if the appropriate model is applied to the data analysis. PMID:15494239

  10. Novel method for the measurement of liquid film thickness during fuel spray impingement on surfaces.

    PubMed

    Henkel, S; Beyrau, F; Hardalupas, Y; Taylor, A M K P

    2016-02-01

    This paper describes the development and application of a novel optical technique for the measurement of liquid film thickness formed on surfaces during the impingement of automotive fuel sprays. The technique makes use of the change of the light scattering characteristics of a metal surface with known roughness, when liquid is deposited. Important advantages of the technique over previously established methods are the ability to measure the time-dependent spatial distribution of the liquid film without a need to add a fluorescent tracer to the liquid, while the measurement principle is not influenced by changes of the pressure and temperature of the liquid or the surrounding gas phase. Also, there is no need for non-fluorescing surrogate fuels. However, an in situ calibration of the dependence of signal intensity on liquid film thickness is required. The developed method can be applied to measure the time-dependent and two-dimensional distribution of the liquid fuel film thickness on the piston or the liner of gasoline direct injection (GDI) engines. The applicability of this technique was evaluated with impinging sprays of several linear alkanes and alcohols with different thermo-physical properties. The surface temperature of the impingement plate was controlled to simulate the range of piston surface temperatures inside a GDI engine. Two sets of liquid film thickness measurements were obtained. During the first set, the surface temperature of the plate was kept constant, while the spray of different fuels interacted with the surface. In the second set, the plate temperature was adjusted to match the boiling temperature of each fuel. In this way, the influence of the surface temperature on the liquid film created by the spray of different fuels and their evaporation characteristics could be demonstrated. PMID:26906828

  11. Thickness of Residual Wetting Film in Liquid-Liquid Displacement in Capillary Channels

    NASA Astrophysics Data System (ADS)

    Beresnev, I. A.; Gaul, W.; Vigil, D.

    2010-12-01

    Core-annular flow is common in nature, representing, for example, how streams of oil, surrounded by water, move in petroleum reservoirs. Oil, typically a non-wetting fluid, tends to occupy the middle (core) part of a channel, while water forms a surrounding wall-wetting film. What is the thickness of this wetting film? Understanding this question may determine the ultimate oil recovery. A classic theory has been in existence for nearly 50 years offering a solution, although in a controversial manner, for moving gas bubbles. On the other hand, an acceptable, experimentally verified theory for a body of one liquid flowing in another has not been available. We develop a hydrodynamic, testable theory providing an explicit relationship between the thickness of the wetting film and fluid properties for a blob of one fluid moving in another, with neither phase being gas. In its relationship to the capillary number Ca, the thickness of the film is predicted to be proportional to Ca2 at lower Ca and to level off at a constant value of about 20 % the channel radius at higher Ca. The thickness of the film is deduced to be approximately unaffected by the viscosity ratio of the fluids. We have conducted our own laboratory experiments and compiled experimental data from other studies, all of which are mutually consistent and confirm the salient features of the theory. At the same time, the classic law, originally deduced for films surrounding moving gas bubbles but often believed to hold for liquids as well, fails to explain the observations.

  12. On the Correlation of Specific Film Thickness and Gear Pitting Life

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.

    2015-01-01

    The effect of the lubrication regime on gear performance has been recognized, qualitatively, for decades. Often the lubrication regime is characterized by the specific film thickness defined as the ratio of lubricant film thickness to the composite surface roughness. It can be difficult to combine results of studies to create a cohesive and comprehensive dataset. In this work gear surface fatigue lives for a wide range of specific film values were studied using tests done with common rigs, speeds, lubricant temperatures, and test procedures. This study includes previously reported data, results of an additional 50 tests, and detailed information from lab notes and tested gears. The dataset comprised 258 tests covering specific film values (0.47 to 5.2). The experimentally determined surface fatigue lives, quantified as 10-percent life estimates, ranged from 8.7 to 86.8 million cycles. The trend is one of increasing life for increasing specific film. The trend is nonlinear. The observed trends were found to be in good agreement with data and recommended practice for gears and bearings. The results obtained will perhaps allow for the specific film parameter to be used with more confidence and precision to assess gear surface fatigue for purpose of design, rating, and technology development.

  13. On the Correlation of Specific Film Thickness and Gear Pitting Life

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy Lewis

    2014-01-01

    The effect of the lubrication regime on gear performance has been recognized, qualitatively, for decades. Often the lubrication regime is characterized by the specific film thickness defined as the ratio of lubricant film thickness to the composite surface roughness. It can be difficult to combine results of studies to create a cohesive and comprehensive dataset. In this work gear surface fatigue lives for a wide range of specific film values were studied using tests done with common rigs, speeds, lubricant temperatures, and test procedures. This study includes previously reported data, results of an additional 50 tests, and detailed information from lab notes and tested gears. The dataset comprised 258 tests covering specific film values [0.47 to 5.2]. The experimentally determined surface fatigue lives, quantified as 10-percent life estimates, ranged from 8.7 to 86.8 million cycles. The trend is one of increasing life for increasing specific film. The trend is nonlinear. The observed trends were found to be in good agreement with data and recommended practice for gears and bearings. The results obtained will perhaps allow for the specific film parameter to be used with more confidence and precision to assess gear surface fatigue for purpose of design, rating, and technology development.

  14. Control of thickness uniformity and grain size in graphene films for transparent conductive electrodes

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Yu, Qingkai; Peng, Peng; Liu, Zhihong; Bao, Jiming; Pei, Shin-Shem

    2012-01-01

    Large-scale and transferable graphene films grown on metal substrates by chemical vapor deposition (CVD) still hold great promise for future nanotechnology. To realize the promise, one of the key issues is to further improve the quality of graphene, e.g., uniform thickness, large grain size, and low defects. Here we grow graphene films on Cu foils by CVD at ambient pressure, and study the graphene nucleation and growth processes under different concentrations of carbon precursor. On the basis of the results, we develop a two-step ambient pressure CVD process to synthesize continuous single-layer graphene films with large grain size (up to hundreds of square micrometers). Scanning electron microscopy and Raman spectroscopy characterizations confirm the film thickness and uniformity. The transferred graphene films on cover glass slips show high electrical conductivity and high optical transmittance that make them suitable as transparent conductive electrodes. The growth mechanism of CVD graphene on Cu is also discussed, and a growth model has been proposed. Our results provide important guidance toward the synthesis of high quality uniform graphene films, and could offer a great driving force for graphene based applications.

  15. Control of thickness uniformity and grain size in graphene films for transparent conductive electrodes.

    PubMed

    Wu, Wei; Yu, Qingkai; Peng, Peng; Liu, Zhihong; Bao, Jiming; Pei, Shin-Shem

    2012-01-27

    Large-scale and transferable graphene films grown on metal substrates by chemical vapor deposition (CVD) still hold great promise for future nanotechnology. To realize the promise, one of the key issues is to further improve the quality of graphene, e.g., uniform thickness, large grain size, and low defects. Here we grow graphene films on Cu foils by CVD at ambient pressure, and study the graphene nucleation and growth processes under different concentrations of carbon precursor. On the basis of the results, we develop a two-step ambient pressure CVD process to synthesize continuous single-layer graphene films with large grain size (up to hundreds of square micrometers). Scanning electron microscopy and Raman spectroscopy characterizations confirm the film thickness and uniformity. The transferred graphene films on cover glass slips show high electrical conductivity and high optical transmittance that make them suitable as transparent conductive electrodes. The growth mechanism of CVD graphene on Cu is also discussed, and a growth model has been proposed. Our results provide important guidance toward the synthesis of high quality uniform graphene films, and could offer a great driving force for graphene based applications. PMID:22173552

  16. Optimum reaction conditions for lead zirconate titanate thick film deposition by ultrasound-assisted hydrothermal method

    NASA Astrophysics Data System (ADS)

    Saigusa, Katsuhiro; Morita, Takeshi

    2016-07-01

    A hydrothermal method can be used to deposit lead zirconate titanate (PZT) films and has several advantages, such as a relatively low reaction temperature and high crystal quality. We developed an ultrasound-assisted hydrothermal method to promote the hydrothermal reactions, which is effective for thick-PZT-film deposition. The first ultrasound-assisted hydrothermal method we developed can synthesize a 7.5 µm PZT film on a titanium substrate. However, for a much thicker film, repeated depositions were required, and the optimum precursor solution for the first deposition was not suitable for repeated depositions. In this study, we attempted to find the optimum precursor solution for depositing a film of sufficient thickness by repeated depositions. As a result, we were able to synthesize a 23.6 µm PZT film on second deposition by changing the ratio of zirconium to titanium ions in the precursor solutions. In addition, a transverse effect transducer was fabricated under optimum conditions and its vibration properties were evaluated.

  17. Analysis of Chemical Reactions between Radical Growth Precursors Adsorbed on Plasma-Deposited Silicon Thin-Film Surfaces

    NASA Astrophysics Data System (ADS)

    Bakos, Tamas; Valipa, Mayur; Maroudas, Dimitrios

    2006-03-01

    The dominant precursor in the plasma deposition of hydrogenated amorphous silicon (a-Si:H) thin films is the SiH3 radical. In this presentation, we report results of first-principles density functional theory calculations on the crystalline Si(001)-(2x1):H surface and molecular-dynamics simulations on a-Si:H surfaces for the interactions between SiH3 radicals adsorbed on Si thin-film surfaces. The analysis reveals that two SiH3 radicals may either form disilane (Si2H6) that desorbs from the surface or undergo a disproportionation reaction producing an SiH2 radical that is incorporated in the film and a silane molecule that is released in the gas phase. The corresponding activation barriers depend on the local atomic coordination of the surface Si atoms; Si2H6 formation is barrierless if both radicals are bonded to overcoordinated surface Si atoms and exhibits barriers in excess of 1 eV for two chemisorbed SiH3 radicals.

  18. A computer solution for the dynamic load, lubricant film thickness, and surface temperatures in spiral-bevel gears

    NASA Technical Reports Server (NTRS)

    Chao, H. C.; Baxter, M.; Cheng, H. S.

    1983-01-01

    A computer method for determining the dynamic load between spiral bevel pinion and gear teeth contact along the path of contact is described. The dynamic load analysis governs both the surface temperature and film thickness. Computer methods for determining the surface temperature, and film thickness are presented along with results obtained for a pair of typical spiral bevel gears.

  19. The dependence of equilibrium film thickness on grain orientation at interphase boundaries in ceramic-ceramic composites

    PubMed

    Knowles; Turan

    2000-06-01

    High-resolution transmission electron microscope observations of hexagonal boron nitride - 3C silicon carbide interphase boundaries suggest that where one or more phases is highly anisotropic, an orientation dependence on equilibrium film thickness can arise. Theoretical considerations of this phenomenon in terms of the equilibrium thickness of an amorphous film between two crystalline media are consistent with the trend seen experimentally. PMID:10841337

  20. Thickness-dependent photocatalytic performance of nanocrystalline TiO2 thin films prepared by sol-gel spin coating

    NASA Astrophysics Data System (ADS)

    Wu, Chung-Yi; Lee, Yuan-Ling; Lo, Yu-Shiu; Lin, Chen-Jui; Wu, Chien-Hou

    2013-09-01

    TiO2 nanocrystalline thin films on soda lime glass have been prepared by sol-gel spin coating. The thin films were characterized for surface morphology, crystal structure, chemical composition, thickness, and transparency by atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ellipsometry, and UV-vis spectrophotometry. The films prepared by titanium tetraisopropoxide (TTIP) as the precursor under pH of 3.5 ± 0.5 and with calcination temperature of 450 ̊C for 3 h exhibited superior homogeneous aggregation, good optical transparency, superhydrophilicity, and reliable thickness. The effect of film thickness on the photocatalytic degradation of acid yellow 17 was investigated under UV irradiation. The photocatalytic activity was strongly correlated with the number of coatings and followed Langmuir-type kinetics. Under the same film thickness, TiO2 thin films prepared by 0.1 M TTIP exhibited more efficient photocatalytic activity than those prepared by 0.3 M TTIP. For thin films prepared by 0.1 M TTIP, the maximum specific photocatalytic activity occurred at 5 coatings with thickness of 93 ± 1 nm. A model was proposed to rationalize the dependence of the film thickness on the photocatalytic activity, which predicts the existence of an optimum film thickness.

  1. Fluorescence and photoelectrochemical behavior of chlorophyll {ital a} adsorbed on a nanocrystalline SnO{sub 2} film

    SciTech Connect

    Bedja, I.; Kamat, P.V.; Hotchandani, S.

    1996-10-01

    Fluorescence and photoelectrochemical studies of chlorophyll {ital a} (Chl {ital a}) adsorbed on nanocrystalline SnO{sub 2} film were carried out. The results of fluorescence and incident photon to current conversion efficiency (IPCE) as a function of applied bias suggest that the fluorescence quenching and the photocarrier generation are interrelated. Fluorescence quenching has thus been utilized to determine the photogeneration efficiency, {eta}({ital e}), of charges in a SnO{sub 2}/Chl {ital a} based photoelectrochemical cell. A value of 0.75 was obtained for {eta}({ital e}) for unbiased cells. With an IPCE of 13{percent}, {eta}({ital e}) of 75{percent}, and a light harvesting efficiency of 70{percent}, the charge collection efficiency of {approximately}23{percent} was evaluated. These results suggest that the losses due to the charge recombination are a major factor that limit the efficiency of the cells. {copyright} {ital 1996 American Institute of Physics.}

  2. Design of Highly Photofunctional Porous Polymer Films with Controlled Thickness and Prominent Microporosity.

    PubMed

    Gu, Cheng; Huang, Ning; Wu, Yang; Xu, Hong; Jiang, Donglin

    2015-09-21

    Porous organic polymers allow the integration of various π-units into robust porous π-networks, but they are usually synthesized as unprocessable solids with poor light-emitting performance as a result of aggregation-related excitation dissipation. Herein, we report a general strategy for the synthesis of highly emissive photofunctional porous polymer films on the basis of a complementary scheme for the structural design of aggregation-induced-emissive π-systems. We developed a high-throughput and facile method for the direct synthesis of large-area porous thin films at the liquid-electrode interface. The approach enables the preparation of microporous films within only a few seconds or minutes and allows precise control over their thickness with sub-nanometer precision. By virtue of rapid photoinduced electron transfer, the thin films can detect explosives with enhanced sensitivity to low parts-per-million levels in a selective manner. PMID:26234636

  3. Design of Highly Photofunctional Porous Polymer Films with Controlled Thickness and Prominent Microporosity

    PubMed Central

    Gu, Cheng; Huang, Ning; Wu, Yang; Xu, Hong; Jiang, Donglin

    2015-01-01

    Porous organic polymers allow the integration of various π-units into robust porous π-networks, but they are usually synthesized as unprocessable solids with poor light-emitting performance as a result of aggregation-related excitation dissipation. Herein, we report a general strategy for the synthesis of highly emissive photofunctional porous polymer films on the basis of a complementary scheme for the structural design of aggregation-induced-emissive π-systems. We developed a high-throughput and facile method for the direct synthesis of large-area porous thin films at the liquid–electrode interface. The approach enables the preparation of microporous films within only a few seconds or minutes and allows precise control over their thickness with sub-nanometer precision. By virtue of rapid photoinduced electron transfer, the thin films can detect explosives with enhanced sensitivity to low parts-per-million levels in a selective manner. PMID:26234636

  4. Direct electrochemical measurements inside a 2000 angstrom thick polymer film by scanning electrochemical microscopy.

    PubMed

    Mirkin, M V; Fan, F R; Bard, A J

    1992-07-17

    An extremely small, conically shaped Pt microelectrode tip (with a radius of 30 nanometers) and the precise positioning capabilities of the scanning electrochemical microscope were used to penetrate a thin (200 nanometers) polymer film and obtain directly the standard potential and kinetic parameters of an electrode reaction within the film. The thickness of the film was determined while it was immersed in and swollen by an electrolyte solution. The film studied was the perfluorosulfonate Nafion containing Os(bpy)(3)(2+) (bpy, 2,2'-bipyridine) cast on an indium tin oxide surface. The steady-state response at the ultramicroelectrode allowed direct determination of the rate constant for heterogeneous electron transfer K(o) and the diffusion coefficient D without complications caused by transport in the liquid phase, charge exchange at the liquid-polymer interface, and resistive drop. PMID:17832832

  5. Thickness Dispersion of Surface Plasmon of Ag Nano-thin Films: Determination by Ellipsometry Iterated with Transmittance Method

    PubMed Central

    Gong, Junbo; Dai, Rucheng; Wang, Zhongping; Zhang, Zengming

    2015-01-01

    Effective optical constants of Ag thin films are precisely determined with effective thickness simultaneously by using an ellipsometry iterated with transmittance method. Unlike the bulk optical constants in Palik's database the effective optical constants of ultrathin Ag films are found to strongly depend on the thickness. According to the optical data two branches of thickness dispersion of surface plasmon energy are derived and agreed with theoretical predication. The thickness dispersion of bulk plasmon is also observed. The influence of substrate on surface plasmon is verified for the first time by using ellipsometry. The thickness dependent effective energy loss function is thus obtained based on this optical method for Ag ultrathin films. This method is also applicable to other ultrathin films and can be used to establish an effective optical database for ultrathin films. PMID:25797217

  6. In-situ and elementally resolved determination of the thickness uniformity of multi-ply films by confocal micro XRF.

    PubMed

    Peng, Song; Liu, Zhiguo; Sun, Tianxi; Wang, Guangfu; Ma, Yongzhong; Ding, Xunliang

    2014-08-01

    Confocal micro X-ray fluorescence (CM-XRF) with quasi-monochromatic excitation based on polycapillary X-ray optics was used to measure the thickness of multi-ply films. The relative errors of measuring an Fe film with a thickness of 16.3 μm and a Cu film with a thickness of 24.5 μm were 7.3% and 0.4%, respectively. The non-destructive and in-situ measurement of the thickness and uniformity of multi-ply films of Cu, Fe and Ni on a silicon surface was performed. CM-XRF was convenient in in-situ and elementally resolved analysis of the thickness of multi-ply films without a cumbersome theoretical correction model. PMID:24705010

  7. High-frequency permeability and permittivity of Ni xZn (1-x)Fe 2O 4 thick film

    NASA Astrophysics Data System (ADS)

    Kulkarni, D. C.; Lonkar, U. B.; Puri, Vijaya

    Magnetic materials such as Ni xZn (1-x)Fe 2O 4 have resonant frequency in high frequency; therefore, they are more useful especially in microwaves. The Ni xZn (1-x)Fe 2O 4 was prepared by the chemical coprecipitation method using citrate precursors, and the fritless thick film was screen printed on alumina substrates. The composition-dependent permeability and permittivity in the high frequency 8-12 GHz are investigated. Using the overlay technique on Ag-thick-film patch antenna, the change in reflectance and transmittance has been measured. The Ni xZn (1-x)Fe 2O 4 thick film, when used as overlay on Ag-thick-film patch antenna, changes the resonance characteristics. The changes in resonance frequency, reflectance and transmittance have been used to calculate the permeability and permittivity of the thick film. Zinc-concentration-dependent changes are obtained.

  8. Relationship between surface viscosity and surface composition of adsorbed surfactant films

    SciTech Connect

    Djabbarah, N.F.; Wasan, D.T.

    1982-02-01

    The single-bubble foaming technique was used to determine the surface excess concentrations of aqueous solutions of sodium lauryl sulfate (SLS) and lauryl alcohol (LOH). The excess concentrations of sodium lauryl sulfate-lauryl alcohol showed that lauryl alcohol is preferentially adsorbed at the surface, but only partially displaces sodium lauryl sulfate. This causes a higher total surface concentration and, consequently, a closer packing of surfactant molecules. The total surface excess concentration increases with an increase in the bulk concentration of the 2 surfactants until the critical micelle concentration (CMC) is reached. At concentrations exceeding the CMC, the surface excess concentration of LOH remains virtually constant, while that of SLS declines. This is due to the formation of SLS micelles. The surface excess concentration data have been used to estimate the extent of molecular packing at the gas/liquid interface and to assess interactions among surfactant molecules in order to explain trends in surface viscosity of a mixed surfactant system adsorbed from an aqueous solution. 30 references.

  9. Generation of thick Ba2YCu3O7 films by aerosol deposition

    NASA Astrophysics Data System (ADS)

    Kodas, T. T.; Engler, E. M.; Lee, V. Y.

    1989-05-01

    Thick superconducting films were fabricated by producing high-purity Ba2YCu3O7 particles by aerosol decomposition in a gaseous flow system, depositing the particles directly from the gas phase onto surfaces by thermophoresis, and then sintering and annealing the deposited particulate films in an oxygen flow. Particulate films with thicknesses of 1 mm were deposited on the inside surfaces of copper tubes and sintered to provide uniform adherent coatings with sharp superconducting transitions above 91 K. High-purity powders based on the Bi-Sr-Ca-Cu-O and Tl-Ca-Ba-Cu-O systems were also produced and sintered to form bulk ceramics with transitions at 80 and 110 K, respectively, suggesting that the process is general and can be used for a variety of materials. Advantages of the process include the ease of obtaining the correct oxygen content and the ability to fabricate thick films of fine grained material while minimizing exposure to carbon and other contaminants.

  10. Using dislocations to probe surface reconstruction in thick freely suspended liquid crystalline films

    NASA Astrophysics Data System (ADS)

    Collett, J. A.; Martinez Zambrano, Daniel

    2015-10-01

    Surface interactions can cause freely suspended thin liquid crystalline films to form phases different from the bulk material, but it is not known what happens at the surface of thick films. Edge dislocations can be used as a marker for the boundary between the bulk center and the reconstructed surface. We use noncontact mode atomic force microscopy to determine the depth of edge dislocations below the surface of freely suspended thick films of 4-n -heptyloxybenzylidene-4-n -heptylaniline (7O.7) in the crystalline B phase. Here, 3.0 ±0.1 nm high steps are found with a width that varies with temperature between 56 and 59 ∘C. Using a strain model for the profile of liquid crystalline layers above an edge dislocation to estimate the depth of the dislocation, we find that the number of reconstructed surface layers increases from 4 to 50 layers as the temperature decreases from 59 to 56 ∘C . This trend tracks the behavior of the phase boundary in the thickness dependent phase diagram of freely suspended films of 7O.7, suggesting that the surface may be reconstructed into a smectic F region.

  11. Test of film thickness based on annular sub-aperture stitching interference

    NASA Astrophysics Data System (ADS)

    Yang, Li-hong; Su, Jun-hong; Chen, Zhi-li

    2010-10-01

    The technology of annular sub-aperture stitching interference used in film thickness testing is an efficient route with the characters of high-resolution and low-cost, which don't need compensation with auxiliary components. In this contribution, the interference methods of film thickness testing and principles of annular sub-aperture stitching are introduced, and then a model of annular sub-aperture stitching is established on the interference phase of thin film; finally, Sub-aperture spatial phases are unwrapped by fast Fourier transform (FFT) algorithms, and based on this, annular image is obtained by Zernike polynomial fitting algorithm and stitching objective function. The processing algorithms program are written and simulated by a computer. A variety of affecting the accuracy of splicing factors of the errors are analyzed in detail, and the solutions are given to reduce the errors, and proposed changes to the existing experimental platform. The results show that the PV value and the RMS value of phase residuals of full aperture splicing are 0.0092λ and 0.0036λ before and after stitching respectively, and it achieves a large aperture high-precision detection of film thickness.

  12. Thickness-dependent quantum oscillations in Cd3As2 thin films

    NASA Astrophysics Data System (ADS)

    Cheng, Peihong; Zhang, Cheng; Liu, Yanwen; Yuan, Xiang; Song, Fengqi; Sun, Qingqing; Zhou, Peng; Zhang, David Wei; Xiu, Faxian

    2016-08-01

    Cd3As2 is a new kind of three-dimensional (3D) Dirac semimetal with extraordinary carrier mobility, which can be viewed as ‘3D graphene’. Theory predicts that Cd3As2 can be driven into a quantum spin Hall insulator with a sizeable band gap by reducing dimensionality. In this letter, we report the systematic growth of undoped Cd3As2 thin films with the thickness of 50 ∼ 900 nm by molecular beam epitaxy. The magneto-transport study on these single-crystalline films shows a high mobility in the range of 3.8 ∼ 9.1 × 103 cm2 · V‑1 · s‑1 and a relative low electron concentration of 1 ∼ 8 × 1017 cm‑3. Significantly, a thickness-induced semimetal-to-semiconductor transition was observed. In contrast with what is expected in the bulk counterpart, the 50 nm-thick Cd3As2 film exhibits semiconducting characteristics, witnessing an emerged bandgap opening when the dimensionality is reduced. Finally, the analyses on the temperature- and angular-dependence of magneto-resistance and Shubnikov-de Hass oscillations reveal a non-trivial to trivial Berry’s phase transition that is in connection with the reduced dimensionality. Our results demonstrate that the Cd3As2 thin films with unique electronic structure and high mobility hold promise for Dirac semimetal device applications.

  13. Film thickness effect on fractality of tin-doped In2O3 thin films

    NASA Astrophysics Data System (ADS)

    Ţălu, Ştefan; Stach, Sebastian; Raoufi, Davood; Hosseinpanahi, Fayegh

    2015-09-01

    In this paper, based on atomic force microscopy (AFM) data the surface morphology of tin-doped In2O3 (ITO) thin films, prepared by electron beam deposition method on float glass substrates, was systematically investigated using the multifractal analysis. Topographical characterization of the ITO film surfaces was realized by a novel multifractal approach which may be applied for AFM data. Detailed surface characterization of the 3D surface topography was obtained using statistical parameters, according to the ISO 25178-2: 2012. Multifractal analysis of the film surfaces revealed that ITO thin films have a multifractal geometry. The generalized dimension D q and the singularity spectrum f( α) provided quantitative values that characterize the local scale properties of film surfaces at nanometer scale. Our results showed that the larger spectrum width Δ α (Δ α = α max - α min) of the multifractal spectra f( α) is related to the larger surface roughness. [Figure not available: see fulltext.

  14. Thickness-dependent nanofriction of a rare gas monolayer sliding on Pb(111) ultrathin films

    NASA Astrophysics Data System (ADS)

    Cai, X. L.; Wang, J. J.; Fu, X. N.; Bai, S. Y.; Niu, C. Y.; Jia, Y.

    2016-02-01

    The friction can be affected dramatically by quantum size effects (QSEs) and edge effects at nanoscale. The modulations of QSEs on nanofriction of a rare gas (RG) monolayer sliding on Pb(111) ultrathin films were investigated by using the first-principles approach within density functional theory (DFT) with van der Waals (vdW) interaction correction. Our findings revealed that there exist even-odd oscillations in the friction with the thickness of Pb(111) substrate and the friction can be tuned up to 30% by the different thicknesses of Pb(111) films. Moreover, such modulation is more obvious for the RG adatoms with larger radius. The underlying physics is that the oscillations of the electronic density of states at Fermi level induce different interactions and energy barriers between RG and Pb(111) films with different thicknesses. Overall, we here propose an approach to tune friction and a way to identify the electronic contribution to friction via the different thicknesses of substrates at nanoscale.

  15. In vitro evaluation of the film thickness of self-etching resin cements.

    PubMed

    Chávez-Lozada, Julio; Urquía-Morales, María Del Carmen

    2014-01-01

    The aim of this study was to evaluate the film thickness of selfetching resin cement. The following materials were used: Group1, Relyx U100 (3M /ESPE); Group 2, BisCem (Bisco); Group 3, Max Cem (Kerr); Group 4, Set (SDI) and Group 5, Relyx ARC (3M/ESPE) as control. Two 5.4 x 76.2 x 1 mm glass slides were marked in the center to identify the area where the material would be placed. A volume of 0.05 ml was used for each specimen material. After 1, 3 and 6 minutes, a 50 N load was applied for one minute. The thickness of each specimen was then measured using a digital micrometer to the nearest 1 μm; (Digimatic, Mitutoyo Corporation, Japan.). Data were analyzed using ANOVA and Bonferroni's multiple comparison tests. No significant difference was found between the materials tested (p = 0.0921) or material/time interaction (p = 0.0864), but there were differences in the time factor (p = 0.0001). At one minute, the thinnest film was Relyx ARC (control) (14 μm), followed by Relyx U100 (17 μm), and Maxcem and SeT (19 μm). At 3 minutes, Group 5 (control) was also the thinnest film (19 μm), followed by Group 1 (21 μm), Group 3 (25 μm), Group 2 (29 μm), and Group 4 (31 μm). At 6 minutes, Group 4 was the thinnest (34 μm), followed by Group 1 (38 μm), Group 5 (40 μm), Group 2 (41 μm) and Group 3 (42 μm). The film thickness of resin cements was influenced by time and polymerization reaction. The film thickness of self-etching cements was low. PMID:25560694

  16. Structural, morphological and optical properties of Ag-AgO thin films with the effect of increasing film thickness and annealing temperature

    NASA Astrophysics Data System (ADS)

    Pal, Anil Kumar; Bharathi Mohan, D.

    2015-10-01

    Ag films of thickness ranging from 5 to 60 nm were deposited by thermal evaporation technique followed by air annealing process with temperature varying from 50 to 250 °C. Morphological properties such as particle size, shape, surface roughness and number particles density were studied by atomic force microscope (AFM). The structural transition from quasi-amorphous to nanocrystalline to crystalline upon increasing film thickness and annealing temperature were studied. Ag films with smallest particle size and surface roughness were achieved up to film thickness of 7 nm. The possibility of surface oxidation of Ag on both as deposited and annealed films was studied through Raman mapping by using confocal Raman spectroscopy. Ag film was X-ray amorphous even after annealing process up to the film thickness of 7 nm and above which the crystallinity reached maximum at 250 °C. The surface plasmon resonance (SPR) with a symmetric line shape due to dipole-dipole interactions was found to be very strong for film thickness of 5 nm at 100 °C, attributed to the formation of smaller Ag NPs size of ∼22 nm with least size distribution and higher particles number density of ∼1625 μm-2 in a self-organized fashion. With an increase of film thickness and annealing temperature, an asymmetric broad absorption arose due to increase in damping of collective electron oscillation on bulky NPs. Theoretical absorption spectra were simulated using extended Maxwell garnet method showing a decent agreement with experimental data. The real and imaginary parts of dielectric constants were determined and plotted for different film thicknesses of as deposited Ag films. Even though the film is oxidized at the surface level, it still can be used for plasmonic sensor applications however the film thickness should be approximately 7 nm for the enhanced result.

  17. Orientation and thickness dependence of magnetization at the interfacesof highly spin-polarized manganite thin films

    SciTech Connect

    Chopdekar, Rajesh V.; Arenholz, Elke; Suzuki, Y.

    2008-08-18

    We have probed the nature of magnetism at the surface of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films. The spin polarization of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films is not intrinsically suppressed at all surfaces and interfaces but is highly sensitive to both the epitaxial strain state as well as the substrate orientation. Through the use of soft x-ray spectroscopy, the magnetic properties of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces have been investigated and compared to bulk magnetometry and resistivity measurements. The magnetization of (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces are more bulk-like as a function of thickness whereas the magnetization at the (001)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interface is suppressed significantly below a layer thickness of 20 nm. Such findings are correlated with the biaxial strain state of the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films; for a given film thickness it is the tetragonal distortion of (001) La{sub 0.7}Sr{sub 0.3}MnO{sub 3} that severely impacts the magnetization, whereas the trigonal distortion for (111)-oriented films and monoclinic distortion for (110)-oriented films have less of an impact. These observations provide evidence that surface magnetization and thus spin polarization depends strongly on the crystal surface orientation as well as epitaxial strain.

  18. Additive-free thick graphene film as an anode material for flexible lithium-ion batteries.

    PubMed

    Rana, Kuldeep; Kim, Seong Dae; Ahn, Jong-Hyun

    2015-04-28

    This work demonstrates a simple route to develop mechanically flexible electrodes for Li-ion batteries (LIBs) that are usable as lightweight effective conducting networks for both cathodes and anodes. Removing electrochemically dead elements, such as binders, conducting agents and metallic current collectors, from the battery components will allow remarkable progress in this area. To investigate the feasibility of using thick, additive-free graphene films as anodes for flexible LIBs, we have synthesized and tested thick, additive-free, freestanding graphene films as anodes, first in a coin cell and further in a flexible full cell. As an anode material in a half cell, it showed a discharge capacity of about 350 mA h g(-1) and maintained nearly this capacity over 50 cycles at various current rates. This film was also tested as an anode material in a full cell with a LiCoO2 cathode and showed good electrochemical performance. Because the graphene-based flexible film showed good performance in half- and full coin cells, we used this film as a flexible anode for flexible LIBs. No conducting agent or binder was used in the anode side, which helped in realizing the flexible LIBs. Using this, we demonstrate a thin, lightweight and flexible lithium ion battery with good electrochemical performance in both its flat and bent states. PMID:25587843

  19. Dielectric and Piezoelectric Properties of PZT Composite Thick Films with Variable Solution to Powder Ratios

    PubMed Central

    Wu, Dawei; Zhou, Qifa; Shung, Koping Kirk.; Bharadwaja, Srowthi N.; Zhang, Dongshe; Zheng, Haixing

    2010-01-01

    The use of PZT films in sliver-mode high-frequency ultrasonic transducers applications requires thick, dense, and crack-free films with excellent piezoelectric and dielectric properties. In this work, PZT composite solutions were used to deposit PZT films >10 μm in thickness. It was found that the functional properties depend strongly on the mass ratio of PZT sol–gel solution to PZT powder in the composite solution. Both the remanent polarization, Pr, and transverse piezoelectric coefficient, e31,f, increase with increasing proportion of the sol–gel solution in the precursor. Films prepared using a solution-to-powder mass ratio of 0.5 have a remanent polarization of 8 μC/cm2, a dielectric constant of 450 (at 1 kHz), and e31,f = −2.8 C/m2. Increasing the solution-to-powder mass ratio to 6, the films were found to have remanent polarizations as large as 37 μC/cm2, a dielectric constant of 1250 (at 1 kHz) and e31,f = −5.8 C/m2. PMID:20376196

  20. Origin of thickness dependence of structural phase transition temperatures in highly strained BiFeO3 thin films

    NASA Astrophysics Data System (ADS)

    Yang, Yongsoo; Beekman, Christianne; Siemons, Wolter; Schlepütz, Christian M.; Senabulya, Nancy; Clarke, Roy; Christen, Hans M.

    2016-03-01

    Two structural phase transitions are investigated in highly strained BiFeO3 thin films as a function of film thickness and temperature via synchrotron x-ray diffraction. Both transition temperatures (upon heating: monoclinic MC to monoclinic MA to tetragonal) decrease as the film becomes thinner. A film-substrate interface layer, evidenced by half-order peaks, contributes to this behavior, but at larger thicknesses (above a few nanometers), the temperature dependence results from electrostatic considerations akin to size effects in ferroelectric phase transitions, but observed here for structural phase transitions within the ferroelectric phase. For ultra-thin films, the tetragonal structure is stable to low temperatures.

  1. (Hg, Sb)Ba2Ca2Cu3O8+δ thick films on YSZ substrates

    NASA Astrophysics Data System (ADS)

    Li, J. Q.; Lam, C. C.; Peacock, G. B.; Hyatt, N. C.; Gameson, I.; Edwards, P. P.; Shields, T. C.; Abell, J. S.

    2000-02-01

    Superconducting thick films of (Hg, Sb)Ba2Ca2Cu3O8+icons/Journals/Common/delta" ALT="delta" ALIGN="MIDDLE"/> have been fabricated on polycrystalline yttria-stabilized-zirconia substrates utilizing an Hg-free precursor film reacted with Hg vapour, released from a solid Hg source, in a sealed quartz tube. The resulting films have been studied by x-ray diffraction, scanning electron microscopy, ac susceptibility and resistance measurement techniques. A high quality Hg(Sb)-1223 superconducting thick film on YSZ can be fabricated by using a pre-melted Hg-free precursor film. The zero resistance superconducting transition temperature in the post-growth oxygenated thick film is in excess of 130 K and the transport critical current density for the film is 510 A cm-2 at 77 K.

  2. Thick film laser induced forward transfer for deposition of thermally and mechanically sensitive materials

    SciTech Connect

    Kattamis, Nicholas T.; Purnick, Priscilla E.; Weiss, Ron; Arnold, Craig B.

    2007-10-22

    Laser forward transfer processes incorporating thin absorbing films can be used to deposit robust organic and inorganic materials but the deposition of more delicate materials has remained elusive due to contamination and stress induced during the transfer process. Here, we present the approach to high resolution patterning of sensitive materials by incorporating a thick film polymer absorbing layer that is able to dissipate shock energy through mechanical deformation. Multiple mechanisms for transfer as a function of incident laser energy are observed and we show viable and contamination-free deposition of living mammalian embryonic stem cells.

  3. Thick film laser induced forward transfer for deposition of thermally and mechanically sensitive materials

    NASA Astrophysics Data System (ADS)

    Kattamis, Nicholas T.; Purnick, Priscilla E.; Weiss, Ron; Arnold, Craig B.

    2007-10-01

    Laser forward transfer processes incorporating thin absorbing films can be used to deposit robust organic and inorganic materials but the deposition of more delicate materials has remained elusive due to contamination and stress induced during the transfer process. Here, we present the approach to high resolution patterning of sensitive materials by incorporating a thick film polymer absorbing layer that is able to dissipate shock energy through mechanical deformation. Multiple mechanisms for transfer as a function of incident laser energy are observed and we show viable and contamination-free deposition of living mammalian embryonic stem cells.

  4. Analysis of thickness of a hydrophobic fluoropolymer film based on electrowetting.

    PubMed

    Ko, Hyojin; Phan, Minh Dinh; Khatua, Dibyendu; Jung, Chan-Hee; Choi, Jae-Hak; Kwon, Oh-Sun; Shin, Kwanwoo

    2013-07-01

    The electrowetting of water drops on a dielectric fluoropolymer film was studied experimentally. The dependence of the contact angles of the water drops on the applied voltage has been well explained in the low-voltage limit by using the classical Young-Lippmann theory. With this theory, the thicknesses of films coated on glass substrates by using a spin-coater were obtained indirectly by fitting the contact angle data and were confirmed by using X-ray reflectometry. The two sets of results showed a good agreement. In addition, we confirmed that the contact angle saturation at high voltage were consistent with Peykov's model. PMID:23909140

  5. Impact of nitrogen doping on growth and hydrogen impurity incorporation of thick nanocrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Gu, Li-Ping; Tang, Chun-Jiu; Jiang, Xue-Fan; L. Pinto, J.

    2011-05-01

    A much larger amount of bonded hydrogen was found in thick nanocrystalline diamond (NCD) films produced by only adding 0.24% N2 into 4% CH4/H2 plasma, as compared to the high quality transparent microcrystalline diamond (MCD) films, grown using the same growth parameters except for nitrogen. These experimental results clearly evidence that defect formation and impurity incorporation (for example, N and H) impeding diamond grain growth is the main formation mechanism of NCD upon nitrogen doping and strongly support the model proposed in the literature that nitrogen competes with CHx (x = 1, 2, 3) growth species for adsorption sites.

  6. Thermoelectric Power-Generation Characteristics of PEDOT:PSS Thin-Film Devices with Different Thicknesses on Polyimide Substrates

    NASA Astrophysics Data System (ADS)

    Anno, Hiroaki; Nishinaka, Takahiko; Hokazono, Masahiro; Oshima, Nobuaki; Toshima, Naoki

    2015-06-01

    We fabricated cast films of complexes of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT:PSS) at various thicknesses, t = 3-20 μm, on flexible polyimide substrates, and studied their thermoelectric properties. We also fabricated in-plane film devices consisting of five couples of PEDOT:PSS and Ag electrodes, measuring their output power characteristics as a function of film thickness. The Seebeck coefficient and electrical conductivity of a PEDOT:PSS film with a thickness of ˜20 μm on a polyimide substrate were ˜15 μV/K and 500 S/cm, respectively, near room temperature. As the film thickness decreased from ˜10 μm to 3 μm, the electrical conductivity increased remarkably to 1200 S/cm, while the Seebeck coefficient remained almost constant with film thickness. The maximum electric power for an in-plane PEDOT:PSS film device with a thickness of 10 μm was 1.3 μW at Δ T = 100 K. Its open-circuit voltage was 7.3 mV, and its internal resistance was 11 Ω. The measured power-generation characteristics of the film device agreed with values estimated from the dependence of thermoelectric properties on film thickness for PEDOT:PSS films on polyimide substrates. Assuming single PEDOT:PSS legs, defined as the direction of heat transport, we estimated the expected electrical power density at Δ T = 100 K as ˜650 μW/cm2 for a film thickness t = 10 μm, and 1400 μW/cm2 for t = 3 μm.

  7. Entropy-Driven Conformational Control of α,ω-Difunctional Bidentate-Dithiol Azo-Based Adsorbates Enables the Fabrication of Thermally Stable Surface-Grafted Polymer Films.

    PubMed

    Lee, Han Ju; Jamison, Andrew C; Lee, T Randall

    2016-06-22

    Thermally stable radical initiator monolayers were prepared from uniquely designed α,ω-difunctional adsorbates with bidentate headgroups for the growth of nanoscale polymer films on metal surfaces. The length of the spacer separating the bidentate headgroups was varied to afford 4,4'-(diazene-1,2-diyl)bis(N-(16-(3,5-bis(mercaptomethyl)phenoxy)hexadecyl)-4-cyanopentanamide) (B16), 4,4'-(diazene-1,2-diyl)bis(N-(16-(3,5-bis(mercapto-methyl)phenoxy)decyl)-4-cyanopentanamide) (B10), and 4,4'-(diazene-1,2-diyl)bis(N-(4-(3,5-bis(mercaptomethyl)phenoxy)butyl)-4-cyanopentanamide) (B4). The structural features of the self-assembled monolayers (SAMs) derived from B16, B10, and B4 were characterized by X-ray photoelectron spectroscopy (XPS), ellipsometry, and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and compared to those derived from an analogous α,ω-difunctional adsorbate with monodentate headgroups, 4,4'-(diazene-1,2-diyl)bis(4-cyano-N-(16-mercaptohexadecyl)pentanamide (M). These studies demonstrate that the conformation (i.e., hairpin vs standing up) of the bidentate initiator adsorbates on gold surfaces was easily controlled by adjusting the concentration of the adsorbates in solution. The results of solution-phase thermal desorption tests revealed that the radical initiator monolayers generated from B16, B10, and B4 exhibit an enhanced thermal stability when compared to those generated from M. Furthermore, a study of the growth of polymer films was performed to evaluate the utility of these new bidentate adsorbate SAMs as film-development platforms for new functional materials and devices. Specifically, surface-grafted polystyrene films were successfully generated from SAMs derived from B16. In contrast, attempts to grow polystyrene films from SAMs derived from M under a variety of analogous conditions were unsuccessful. PMID:27219525

  8. Atmospheric pressure spatial atomic layer deposition web coating with in situ monitoring of film thickness

    SciTech Connect

    Yersak, Alexander S.; Lee, Yung C.; Spencer, Joseph A.; Groner, Markus D.

    2014-01-15

    Spectral reflectometry was implemented as a method for in situ thickness monitoring in a spatial atomic layer deposition (ALD) system. Al{sub 2}O{sub 3} films were grown on a moving polymer web substrate at 100 °C using an atmospheric pressure ALD web coating system, with film growth of 0.11–0.13 nm/cycle. The modular coating head design and the in situ monitoring allowed for the characterization and optimization of the trimethylaluminum and water precursor exposures, purge flows, and web speed. A thickness uniformity of ±2% was achieved across the web. ALD cycle times as low as 76 ms were demonstrated with a web speed of 1 m/s and a vertical gap height of 0.5 mm. This atmospheric pressure ALD system with in situ process control demonstrates the feasibility of low-cost, high throughput roll-to-roll ALD.

  9. Thickness-dependent thin-film resistivity: Application of quantitative scanning-tunneling-microscopy imaging

    NASA Astrophysics Data System (ADS)

    Reiss, G.; Hastreiter, E.; Brückl, H.; Vancea, J.

    1991-02-01

    The dependence of thin-film resistivity on the thickness is known to be strongly influenced by the interaction of the conduction electrons with the surface. Great efforts have been made in recent years, mainly concerning the quantum-mechanical description of the surface scattering. Detailed discussions of this problem, however, suffer from the lack of information concerning the real topography of thin-film surfaces. The development of scanning tunneling microscopy (STM) now gives the chance of direct, quantitative imaging. In this paper, we use the topographic information of STM to improve the fitting of theoretical descriptions to the measured thickness-dependence of the resistivity. The transport parameters obtained from these calculations show a high degree of physical consistency.

  10. Sub-30 nm thick plasmonic films and structures with ultralow loss.

    PubMed

    Teo, Ee Jin; Toyoda, Noriaki; Yang, Chengyuan; Wang, Bing; Zhang, Nan; Bettiol, Andrew A; Teng, Jing Hua

    2014-03-21

    We report an alternative method of producing sub-30 nm thick silver films and structures with ultralow loss using gas cluster ion beam irradiation (GCIB). We have direct evidence showing that scattering from grain boundaries and voids rather than surface roughness are the main mechanisms for the increase in loss with reducing thickness. Using GCIB irradiation, we demonstrate the ability to reduce these scattering effects simultaneously through nanoscale surface smoothing, increase in grain width and lower percolation threshold. Significant improvement in electrical and optical properties by up to 4 times is obtained, before deviation from bulk silver properties starts to occur at 12 nm. We show that this is an enabling technology that can be applied post fabrication to metallic films or lithographically patterned nanostructures for enhanced plasmonic performance, especially in the ultrathin regime. PMID:24504045

  11. Ferroelectric domain inversion and its stability in lithium niobate thin film on insulator with different thicknesses

    NASA Astrophysics Data System (ADS)

    Shao, Guang-hao; Bai, Yu-hang; Cui, Guo-xin; Li, Chen; Qiu, Xiang-biao; Geng, De-qiang; Wu, Di; Lu, Yan-qing

    2016-07-01

    Ferroelectric domain inversion and its effect on the stability of lithium niobate thin films on insulator (LNOI) are experimentally characterized. Two sets of specimens with different thicknesses varying from submicron to microns are selected. For micron thick samples (˜28 μm), domain structures are achieved by pulsed electric field poling with electrodes patterned via photolithography. No domain structure deterioration has been observed for a month as inspected using polarizing optical microscopy and etching. As for submicron (540 nm) films, large-area domain inversion is realized by scanning a biased conductive tip in a piezoelectric force microscope. A graphic processing method is taken to evaluate the domain retention. A domain life time of 25.0 h is obtained and possible mechanisms are discussed. Our study gives a direct reference for domain structure-related applications of LNOI, including guiding wave nonlinear frequency conversion, nonlinear wavefront tailoring, electro-optic modulation, and piezoelectric devices.

  12. Oil film thickness measurement using airborne laser-induced water Raman backscatter

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Swift, R. N.

    1980-01-01

    The use of laser-induced water Raman backscatter for remote thin oil film detection and thickness measurement is reported here for the first time. A 337.1-nm nitrogen laser was used to excite the 3400-cm-1 OH stretch band of natural ocean water beneath the oil slick from an altitude of 150 m. The signal strength of the 381-nm water Raman backscatter was always observed to depress when the oil was encountered and then return to its original undepressed value after complete aircraft traversal of the floating slick. After removal of background and oil fluorescence contributions, the ratio of the depressed-to-undepressed airborne water Raman signal intensities, together with laboratory measured oil extinction coefficients, is used to calculate the oil film thickness.

  13. Correlation of elastohydrodynamic film thickness measurements for fluorocarbon type 2 ester, and polyphenyl ether lubricants

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Parker, R. J.; Zaretsky, E. V.

    1974-01-01

    A minimum films thickness correlation applicable to heavily loaded elastohydrodynamic (EHD) contacts was formulated from experimental data obtained by an X-ray transmission technique. The correlation, based on data generated with fluorocarbon, type II ester, and polyphenyl ether lubricants, extends a previous analysis developed from data for a synthetic paraffinic oil. The resulting correlation represents the data of the four lubricants reasonably well over a large range of operating conditions. Contained within the derived relation is a factor to account for the high-load dependence displayed by the measurements beyond that which is provided for by the theory. Thermal corrections applied to a commonly used film thickness formula showed little improvement to the general disagreement that exists between theory and test. Choice of contact geometry and material are judged to have a relatively mild influence on the form of the semiempirical model.

  14. Evaluation of Cadmium-Free Thick Film Materials on Alumina Substrates

    SciTech Connect

    L. H. Perdieu

    2009-09-01

    A new cadmium-free material system was successfully evaluated for the fabrication of thick film hybrid microcircuits at Honeywell Federal Manufacturing & Technologies (FM&T). The characterization involved screen printing, drying and firing two groups of resistor networks which were made using the current material system and the cadmium-free material system. Electrical, environmental and adhesion tests were performed on both groups to determine the more suitable material system. Additionally, untrimmed test coupons were evaluated to further characterize the new materials. The cadmiumfree material system did as well or better than the current material system. Therefore, the new cadmium-free material system was approved for use on production thick film product.

  15. Surface-dominated conduction in a 6 nm thick Bi2Se3 thin film.

    PubMed

    He, Liang; Xiu, Faxian; Yu, Xinxin; Teague, Marcus; Jiang, Wanjun; Fan, Yabin; Kou, Xufeng; Lang, Murong; Wang, Yong; Huang, Guan; Yeh, Nai-Chang; Wang, Kang L

    2012-03-14

    We report a direct observation of surface dominated conduction in an intrinsic Bi(2)Se(3) thin film with a thickness of six quintuple layers grown on lattice-matched CdS (0001) substrates by molecular beam epitaxy. Shubnikov-de Haas oscillations from the topological surface states suggest that the Fermi level falls inside the bulk band gap and is 53 ± 5 meV above the Dirac point, which is in agreement with 70 ± 20 meV obtained from scanning tunneling spectroscopies. Our results demonstrate a great potential of producing genuine topological insulator devices using Dirac Fermions of the surface states, when the film thickness is pushed to nanometer range. PMID:22316380

  16. DETERMINATION OF LIQUID FILM THICKNESS FOLLOWING DRAINING OF CONTACTORS, VESSELS, AND PIPES IN THE MCU PROCESS

    SciTech Connect

    Poirier, M; Fernando Fondeur, F; Samuel Fink, S

    2006-06-06

    The Department of Energy (DOE) identified the caustic side solvent extraction (CSSX) process as the preferred technology to remove cesium from radioactive waste solutions at the Savannah River Site (SRS). As a result, Washington Savannah River Company (WSRC) began designing and building a Modular CSSX Unit (MCU) in the SRS tank farm to process liquid waste for an interim period until the Salt Waste Processing Facility (SWPF) begins operations. Both the solvent and the strip effluent streams could contain high concentrations of cesium which must be removed from the contactors, process tanks, and piping prior to performing contactor maintenance. When these vessels are drained, thin films or drops will remain on the equipment walls. Following draining, the vessels will be flushed with water and drained to remove the flush water. The draining reduces the cesium concentration in the vessels by reducing the volume of cesium-containing material. The flushing, and subsequent draining, reduces the cesium in the vessels by diluting the cesium that remains in the film or drops on the vessel walls. MCU personnel requested that Savannah River National Laboratory (SRNL) researchers conduct a literature search to identify models to calculate the thickness of the liquid films remaining in the contactors, process tanks, and piping following draining of salt solution, solvent, and strip solution. The conclusions from this work are: (1) The predicted film thickness of the strip effluent is 0.010 mm on vertical walls, 0.57 mm on horizontal walls and 0.081 mm in horizontal pipes. (2) The predicted film thickness of the salt solution is 0.015 mm on vertical walls, 0.74 mm on horizontal walls, and 0.106 mm in horizontal pipes. (3) The predicted film thickness of the solvent is 0.022 mm on vertical walls, 0.91 mm on horizontal walls, and 0.13 mm in horizontal pipes. (4) The calculated film volume following draining is: (a) Salt solution receipt tank--1.6 gallons; (b) Salt solution feed

  17. Thickness Dependence of the Quantum Anomalous Hall Effect in Magnetic Topological Insulator Films.

    PubMed

    Feng, Xiao; Feng, Yang; Wang, Jing; Ou, Yunbo; Hao, Zhenqi; Liu, Chang; Zhang, Zuocheng; Zhang, Liguo; Lin, Chaojing; Liao, Jian; Li, Yongqing; Wang, Li-Li; Ji, Shuai-Hua; Chen, Xi; Ma, Xucun; Zhang, Shou-Cheng; Wang, Yayu; He, Ke; Xue, Qi-Kun

    2016-08-01

    The evolution of the quantum anomalous Hall effect with the thickness of Cr-doped (Bi,Sb)2 Te3 magnetic topological insulator films is studied, revealing how the effect is caused by the interplay of the surface states, band-bending, and ferromagnetic exchange energy. Homogeneity in ferromagnetism is found to be the key to high-temperature quantum anomalous Hall material. PMID:27166762

  18. [Determination of film thickness, component and content based on glass surface by using XRF spectrometry].

    PubMed

    Mei, Yan; Ma, Mi-Xia; Nie, Zuo-Ren

    2013-12-01

    Film thickness, component and content based on glass surface were determined by using XRF technic, measure condition and instrument work condition in every layer were set and adjusted for the best measure effect for every element. Background fundamental parameter (BG-FP) method was built up. Measure results with this method were consistent with the actual preparation course and the method could fit to production application. PMID:24611412

  19. Characterization of Thick and Thin Film SiCN for Pressure Sensing at High Temperatures

    PubMed Central

    Leo, Alfin; Andronenko, Sergey; Stiharu, Ion; Bhat, Rama B.

    2010-01-01

    Pressure measurement in high temperature environments is important in many applications to provide valuable information for performance studies. Information on pressure patterns is highly desirable for improving performance, condition monitoring and accurate prediction of the remaining life of systems that operate in extremely high temperature environments, such as gas turbine engines. A number of technologies have been recently investigated, however these technologies target specific applications and they are limited by the maximum operating temperature. Thick and thin films of SiCN can withstand high temperatures. SiCN is a polymer-derived ceramic with liquid phase polymer as its starting material. This provides the advantage that it can be molded to any shape. CERASET™ also yields itself for photolithography, with the addition of photo initiator 2, 2-Dimethoxy-2-phenyl-acetophenone (DMPA), thereby enabling photolithographical patterning of the pre-ceramic polymer using UV lithography. SiCN fabrication includes thermosetting, crosslinking and pyrolysis. The technology is still under investigation for stability and improved performance. This work presents the preparation of SiCN films to be used as the body of a sensor for pressure measurements in high temperature environments. The sensor employs the phenomenon of drag effect. The pressure sensor consists of a slender sensitive element and a thick blocking element. The dimensions and thickness of the films depend on the intended application of the sensors. Fabrication methods of SiCN ceramics both as thin (about 40–60 μm) and thick (about 2–3 mm) films for high temperature applications are discussed. In addition, the influence of thermosetting and annealing processes on mechanical properties is investigated. PMID:22205871

  20. Development of an all-metal thick film cost affective metallization system for solar cells

    NASA Technical Reports Server (NTRS)

    Ross, B.

    1981-01-01

    An economical thick film solar cell contact for high volume production of low cost silicon solar array modules was investigated. All metal screenable pastes using base metals were studied. Solar cells with junction depths varying by a factor of 3.3, with and without a deposited oxide coating were used. Cells were screened and fired by a two step firing process. Adhesion and metallurgical results are unsatisfactory. No electrical information is obtained due to inadequate contact adhesion.

  1. Characterization of thick and thin film SiCN for pressure sensing at high temperatures.

    PubMed

    Leo, Alfin; Andronenko, Sergey; Stiharu, Ion; Bhat, Rama B

    2010-01-01

    Pressure measurement in high temperature environments is important in many applications to provide valuable information for performance studies. Information on pressure patterns is highly desirable for improving performance, condition monitoring and accurate prediction of the remaining life of systems that operate in extremely high temperature environments, such as gas turbine engines. A number of technologies have been recently investigated, however these technologies target specific applications and they are limited by the maximum operating temperature. Thick and thin films of SiCN can withstand high temperatures. SiCN is a polymer-derived ceramic with liquid phase polymer as its starting material. This provides the advantage that it can be molded to any shape. CERASET™ also yields itself for photolithography, with the addition of photo initiator 2, 2-Dimethoxy-2-phenyl-acetophenone (DMPA), thereby enabling photolithographical patterning of the pre-ceramic polymer using UV lithography. SiCN fabrication includes thermosetting, crosslinking and pyrolysis. The technology is still under investigation for stability and improved performance. This work presents the preparation of SiCN films to be used as the body of a sensor for pressure measurements in high temperature environments. The sensor employs the phenomenon of drag effect. The pressure sensor consists of a slender sensitive element and a thick blocking element. The dimensions and thickness of the films depend on the intended application of the sensors. Fabrication methods of SiCN ceramics both as thin (about 40-60 μm) and thick (about 2-3 mm) films for high temperature applications are discussed. In addition, the influence of thermosetting and annealing processes on mechanical properties is investigated. PMID:22205871

  2. Development of an all-metal thick film cost effective metallization system for solar cells

    NASA Technical Reports Server (NTRS)

    Ross, B.; Parker, J.

    1983-01-01

    Improved thick film solar cell contacts for the high volume production of low cost silicon solar arrays are needed. All metal screenable pastes made from economical base metals and suitable for application to low to high conductivity silicon were examined. Silver fluoride containing copper pastes and fluorocarbon containing copper pastes were discussed. The effect of hydrogen on the adhesion of metals to silicon was investigated. A cost analysis of various paste materials is provided.

  3. Thickness dependence of Young's modulus and residual stress of sputtered aluminum nitride thin films

    NASA Astrophysics Data System (ADS)

    Schneider, M.; Bittner, A.; Schmid, U.

    2014-11-01

    Aluminum nitride thin films are commonly used as active layer in micro-/nanomachined devices due to their piezoelectric properties. In order to predict the performance of advanced device architectures, careful modelling and simulation using techniques such as finite element analysis are of the utmost importance. An accurate knowledge of the corresponding thin film material properties is therefore required. This work focuses on the mechanical properties residual stress and Young's modulus over a wide thickness range from 100 to 1200 nm. The load-deflection technique is used to measure the bending curve of a circumferentially clamped, circular aluminum nitride diaphragm under a uniformly distributed pressure load. The bending curves are analyzed using an advanced analytical approach rather than commonly used models for load-deflection methods, thus resulting in a higher accuracy. It is found that the Young's modulus is nearly independent of film thickness, whereas the tensile residual stress exhibits a maximum at a thickness of about 600 nm. A thorough discussion of possible error sources is presented and approaches to minimize their impact are discussed.

  4. A reliable control system for measurement on film thickness in copper chemical mechanical planarization system

    NASA Astrophysics Data System (ADS)

    Li, Hongkai; Qu, Zilian; Zhao, Qian; Tian, Fangxin; Zhao, Dewen; Meng, Yonggang; Lu, Xinchun

    2013-12-01

    In recent years, a variety of film thickness measurement techniques for copper chemical mechanical planarization (CMP) are subsequently proposed. In this paper, the eddy-current technique is used. In the control system of the CMP tool developed in the State Key Laboratory of Tribology, there are in situ module and off-line module for measurement subsystem. The in situ module can get the thickness of copper film on wafer surface in real time, and accurately judge when the CMP process should stop. This is called end-point detection. The off-line module is used for multi-points measurement after CMP process, in order to know the thickness of remained copper film. The whole control system is structured with two levels, and the physical connection between the upper and the lower is achieved by the industrial Ethernet. The process flow includes calibration and measurement, and there are different algorithms for two modules. In the process of software development, C++ is chosen as the programming language, in combination with Qt OpenSource to design two modules' GUI and OPC technology to implement the communication between the two levels. In addition, the drawing function is developed relying on Matlab, enriching the software functions of the off-line module. The result shows that the control system is running stably after repeated tests and practical operations for a long time.

  5. A reliable control system for measurement on film thickness in copper chemical mechanical planarization system.

    PubMed

    Li, Hongkai; Qu, Zilian; Zhao, Qian; Tian, Fangxin; Zhao, Dewen; Meng, Yonggang; Lu, Xinchun

    2013-12-01

    In recent years, a variety of film thickness measurement techniques for copper chemical mechanical planarization (CMP) are subsequently proposed. In this paper, the eddy-current technique is used. In the control system of the CMP tool developed in the State Key Laboratory of Tribology, there are in situ module and off-line module for measurement subsystem. The in situ module can get the thickness of copper film on wafer surface in real time, and accurately judge when the CMP process should stop. This is called end-point detection. The off-line module is used for multi-points measurement after CMP process, in order to know the thickness of remained copper film. The whole control system is structured with two levels, and the physical connection between the upper and the lower is achieved by the industrial Ethernet. The process flow includes calibration and measurement, and there are different algorithms for two modules. In the process of software development, C++ is chosen as the programming language, in combination with Qt OpenSource to design two modules' GUI and OPC technology to implement the communication between the two levels. In addition, the drawing function is developed relying on Matlab, enriching the software functions of the off-line module. The result shows that the control system is running stably after repeated tests and practical operations for a long time. PMID:24387462

  6. A reliable control system for measurement on film thickness in copper chemical mechanical planarization system

    SciTech Connect

    Li, Hongkai; Qu, Zilian; Zhao, Qian; Tian, Fangxin; Zhao, Dewen; Meng, Yonggang; Lu, Xinchun

    2013-12-15

    In recent years, a variety of film thickness measurement techniques for copper chemical mechanical planarization (CMP) are subsequently proposed. In this paper, the eddy-current technique is used. In the control system of the CMP tool developed in the State Key Laboratory of Tribology, there are in situ module and off-line module for measurement subsystem. The in situ module can get the thickness of copper film on wafer surface in real time, and accurately judge when the CMP process should stop. This is called end-point detection. The off-line module is used for multi-points measurement after CMP process, in order to know the thickness of remained copper film. The whole control system is structured with two levels, and the physical connection between the upper and the lower is achieved by the industrial Ethernet. The process flow includes calibration and measurement, and there are different algorithms for two modules. In the process of software development, C++ is chosen as the programming language, in combination with Qt OpenSource to design two modules’ GUI and OPC technology to implement the communication between the two levels. In addition, the drawing function is developed relying on Matlab, enriching the software functions of the off-line module. The result shows that the control system is running stably after repeated tests and practical operations for a long time.

  7. Room-temperature growth of Ni-Zn-Cu ferrite/PTFE composite thick films on PET via aerosol deposition

    NASA Astrophysics Data System (ADS)

    Kim, Hyung-Jun; Kwon, Oh-Yun; Jang, Chan-Ick; Kim, Tae Kyoung; Oh, Jun Rok; Yoon, Young Joon; Kim, Jong-Hee; Nam, Song-Min; Koh, Jung-Hyuk

    2013-11-01

    Ni-Zn-Cu ferrite and Ni-Zn-Cu ferrite/poly-tetra-fluoro-ethylene (PTFE) composite-thick-films were grown at room temperature on polyethylene terephthalate (PET) sheets via aerosol deposition (AD) as a magnetic shielding sheet for near-field communication. An 80 µm-thick Ni-Zn-Cu ferrite/PTFE composite-thick-film was grown on the PET sheet when 2.0 wt. % PTFE starting powder was used. The real relative permeability µ r ' and the imaginary permeability µ r ″ of the Ni-Zn-Cu ferrite thick film were 10.1 and 2.1 at 13.56 MHz, respectively. In the case of the composite thick film, µ r ' and µ r ″ decreased to 3.9 and 1.3, respectively, at 13.56 MHz; with the addition of the PTFE.

  8. Anomalous thickness dependence of quality factor in TiN film resonators grown on functionalized Si substrates

    NASA Astrophysics Data System (ADS)

    Xu, Peng; Kohler, Tim; Lock, Evgeniya; Rosen, Yaniv; Ramanayaka, Aruna; Guchhait, Samaresh; Osborn, Kevin

    Various properties affect the quality factor of superconducting resonators at millikelvin temperatures including the presence of nanoscale interfacial dielectric films and residual quasiparticles. Superconducting titanium nitride is polycrystalline such that growth phases may also affect the resonator quality. Here, we functionalize Si substrates in different hydrophobic and hydrophilic plasma environments, sputter titanium nitride on top and pattern the latter films into resonators. For each functionalization we study the quality factor dependence on the superconducting film thickness, where the thicknesses are changed only between 25 and 50 nm. As expected, most functionalizations reveal very little quality factor dependence on superconducting film thickness. However, other functionalizations dramatically, and even anomalously, increase or decrease the quality with thickness. For example, oxygen plasma functionalization causes the quality factor to increase by a factor of more than ten at single photon power with increased thickness. We report on the progress towards finding the intrinsic reason for strong quality factor dependences on surface functionalization.

  9. Critical thickness and strain relaxation in molecular beam epitaxy-grown SrTiO3 films

    NASA Astrophysics Data System (ADS)

    Wang, Tianqi; Ganguly, Koustav; Marshall, Patrick; Xu, Peng; Jalan, Bharat

    2013-11-01

    We report on the study of the critical thickness and the strain relaxation in epitaxial SrTiO3 film grown on (La0.3Sr0.7)(Al0.65Ta0.35)O3 (001) (LSAT) substrate using the hybrid molecular beam epitaxy approach. No change in the film's lattice parameter (both the in-plane and the out-of-plane) was observed up to a film thickness of 180 nm, which is in sharp contrast to the theoretical critical thickness of ˜12 nm calculated using the equilibrium theory of strain relaxation. For film thicknesses greater than 180 nm, the out-of-plane lattice parameter was found to decrease hyperbolically in an excellent agreement with the relaxation via forming misfit dislocations. Possible mechanisms are discussed by which the elastic strain energy can be accommodated prior to forming misfit dislocations leading to such anomalously large critical thickness.

  10. Influence of thickness on physical properties of vacuum evaporated polycrystalline CdTe thin films for solar cell applications

    NASA Astrophysics Data System (ADS)

    Chander, Subhash; Dhaka, M. S.

    2016-02-01

    This paper presents the influence of thickness on physical properties of polycrystalline CdTe thin films. The thin films of thickness 450 nm, 650 nm and 850 nm were deposited employing thermal vacuum evaporation technique on glass and indium tin oxide (ITO) coated glass substrates. The physical properties of these as-grown thin films were investigated employing the X-ray diffraction (XRD), source meter, UV-Vis spectrophotometer, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The structural analysis reveals that the films have zinc-blende cubic structure and polycrystalline in nature with preferred orientation (111). The structural parameters like lattice constant, interplanar spacing, grain size, strain, dislocation density and number of crystallites per unit area are calculated. The average grain size and optical band gap are found in the range 15.16-21.22 nm and 1.44-1.63 eV respectively and observed to decrease with thickness. The current-voltage characteristics show that the electrical conductivity is observed to decrease with thickness. The surface morphology shows that films are free from crystal defects like pin holes and voids as well as homogeneous and uniform. The EDS patterns show the presence of cadmium and tellurium elements in the as grown films. The experimental results reveal that the film thickness plays significant role on the physical properties of as-grown CdTe thin films and higher thickness may be used as absorber layer to solar cells applications.

  11. An intelligent thick-film gas sensor: Development and preliminary tests

    NASA Astrophysics Data System (ADS)

    Lauf, R. J.; Hoffheins, B. S.; Walls, C. A.

    1987-05-01

    Thick-film techniques were used to create a gas sensor that has a semiconducting oxide surface whose catalytic activity varies from point to point. An integral heater causes the oxide film to react with combustible gases; the electrical resistance of the oxide film is mapped through an array of electrodes to yield a signature that depends on how a particular gas reacts to each of the different areas on the sensor. The catalytic activity can be varied by establishing a thermal gradient across the sensor, by distributing different catalysts in different areas, or by a combination of both effects. For simple cases, the signature can be related to the functional groups present in the gas. As an example, using a uniform distribution of platinum and a thermal gradient, alcohols, ketones, and alkanes have distinctly different signatures.

  12. Thickness-dependent cooperative aging in polycrystalline films of antiferromagnet CoO

    NASA Astrophysics Data System (ADS)

    Ma, Tianyu; Cheng, Xiang; Boettcher, Stefan; Urazhdin, Sergei; Novozhilova, Lydia

    2016-07-01

    We demonstrate that thin polycrystalline films of antiferromagnet CoO, in bilayers with ferromagnetic Permalloy, exhibit slow power-law aging of their magnetization state. The aging characteristics are remarkably similar to those previously observed in thin epitaxial Fe50Mn50 films, indicating that these behaviors are likely generic to ferromagnet/antiferromagnet bilayers. In very thin films, aging is observed over a wide temperature range. In thicker CoO, aging effects become reduced at low temperatures. Aging entirely disappears for large CoO thicknesses. We also investigate the dependence of aging characteristics on temperature and magnetic history. Analysis shows that the observed behaviors are inconsistent with the Neel-Arrhenius model of thermal activation, and are instead indicative of cooperative aging of the antiferromagnet. Our results provide new insights into the mechanisms controlling the stationary states and dynamics of ferromagnet/antiferromagnet bilayers, and potentially other frustrated magnetic systems.

  13. Performance Evaluation of an Oxygen Sensor as a Function of the Samaria Doped Ceria Film Thickness

    SciTech Connect

    Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Nachimuthu, Ponnusamy; Engelhard, Mark H.; Shutthanandan, V.; Jiang, Weilin; Thevuthasan, Suntharampillai; Kayani, Asghar N.; Prasad, Shalini

    2010-12-01

    The current demand in the automobile industry is in the control of air-fuel mixture in the combustion engine of automobiles. Oxygen partial pressure can be used as an input parameter for regulating or controlling systems in order to optimize the combustion process. Our goal is to identify and optimize the material system that would potentially function as the active sensing material for such a device that monitors oxygen partial pressure in these systems. We have used thin film samaria doped ceria (SDC) as the sensing material for the sensor operation, exploiting the fact that at high temperatures, oxygen vacancies generated due to samarium doping act as conducting medium for oxygen ions which hop through the vacancies from one side to the other contributing to an electrical signal. We have recently established that 6 atom % Sm doping in ceria films has optimum conductivity. Based on this observation, we have studied the variation in the overall conductivity of 6 atom % samaria doped ceria thin films as a function of thickness in the range of 50 nm to 300 nm at a fixed bias voltage of 2 volts. A direct proportionality in the increase in the overall conductivity is observed with the increase in sensing film thickness. For a range of oxygen pressure values from 1 mTorr to 100 Torr, a tolerable hysteresis error, good dynamic response and a response time of less than 10 seconds was observed

  14. Thickness Dependency of Thin Film Samaria Doped Ceria for Oxygen Sensing

    SciTech Connect

    Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Jiang, Weilin; Varga, Tamas; Nachimuthu, Ponnusamy; Engelhard, Mark H.; Shutthanandan, V.; Thevuthasan, Suntharampillai; Kayani, Asghar N.; Prasad, Shalini

    2011-01-01

    High temperature oxygen sensors are widely used for exhaust gas monitoring in automobiles. This particular study explores the use of thin film single crystalline samaria doped ceria as the oxygen sensing material. Desired signal to noise ratio can be achieved in a material system with high conductivity. From previous studies it is established that 6 atomic percent samarium doping is the optimum concentration for thin film samaria doped ceria to achieve high ionic conductivity. In this study, the conductivity of the 6 atomic percent samaria doped ceria thin film is measured as a function of the sensing film thickness. Hysteresis and dynamic response of this sensing platform is tested for a range of oxygen pressures from 0.001 Torr to 100 Torr for temperatures above 673 K. An attempt has been made to understand the physics behind the thickness dependent conductivity behavior of this sensing platform by developing a hypothetical operating model and through COMSOL simulations. This study can be used to identify the parameters required to construct a fast, reliable and compact high temperature oxygen sensor.

  15. Thick growing multilayer nanobrick wall thin films: super gas barrier with very few layers.

    PubMed

    Guin, Tyler; Krecker, Michelle; Hagen, David Austin; Grunlan, Jaime C

    2014-06-24

    Recent work with multilayer nanocoatings composed of polyelectrolytes and clay has demonstrated the ability to prepare super gas barrier layers from water that rival inorganic CVD-based films (e.g., SiOx). In an effort to reduce the number of layers required to achieve a very low oxygen transmission rate (OTR (<0.01 cc/m(2)·day·atm)) in these nanocoatings, buffered cationic chitosan (CH) and vermiculite clay (VMT) were deposited using layer-by-layer (LbL) assembly. Buffering the chitosan solution and its rinse with 50 mM Trizma base increased the thickness of these films by an order of magnitude. The OTR of a 1.6-μm-thick, six-bilayer film was 0.009 cc/m(2)·day·atm, making this the best gas barrier reported for such a small number of layers. This simple modification to the LbL process could likely be applied more universally to produce films with the desired properties much more quickly. PMID:24914613

  16. Estimation of appropriate lubricating film thickness in ceramic-on-ceramic hip prostheses

    NASA Astrophysics Data System (ADS)

    Tauviqirrahman, M.; Muchammad, Bayuseno, A. P.; Ismail, R.; Saputra, E.; Jamari, J.

    2016-04-01

    Artificial hip prostheses, consisting of femoral head and acetabular cup are widely used and have affected the lives of many people.However, the primary issue associated with the long term performance of hip prostheses is loosening induced by excessive wear during daily activity. Therefore, an effective lubrication is necessary to significantly decrease the wear. To help understand the lubricating performance of such typical hip joint prostheses, in the present paper a hydrodynamic lubrication model based on Reynolds equationwas introduced. The material pairs of ceramic acetabular cup against ceramic femoral head was investegated.The main aim of this study is to investigate of the effect of loading on the formation of lubricating film thickness.The model of a ball-in-socket configuration was considered assuming that the cup was stationary while the ball was to rotate at a steady angular velocityvarying loads.Based on simulation result, it was found that to promote fluid film lubrication and prevent the contacting components leading to wear, the film thickness of lubricant should be determined carefully based on the load applied. This finding may have useful implication in predicting the failure of lubricating synovial fluid film and wear generation in hip prostheses.

  17. Fracture Mechanism and Toughness Optimization of Macroscopic Thick Graphene Oxide Film

    PubMed Central

    Ye, Shibing; Chen, Bin; Feng, Jiachun

    2015-01-01

    Combined high strength and toughness of film materials are rather important for their industrial applications. As a new class of films, graphene oxide films (GOFs) attract intense attention in many applications but are frequently divergent, inconsistent, and poorly reproducible in their mechanical properties. In this study, we first demonstrate that different chemical compositions and assembly structures probably are responsible for the difference in elongations between cast GOFs and filtration GOFs. Comprehensive analysis of the morphologies and mechanical properties indicates that the enhanced elongation of the thick cast GOFs is mainly attributed to the presence of a unique skin-wrinkles-skin structure, which more easily forms in cast GOFs than in filtration counterparts. On the basis of this finding, we attempt to optimize the strength-toughness performance of the cast GOFs by adjusting their structures. With an appropriate thickness of 12.5 μm, the GOFs can achieve an ultrahigh toughness up to 4.37 MJ m−3, which is even comparable to the polymer-toughening graphene/GO-based paper-like materials. Such an optimization of the mechanical properties from the perspective of skin-wrinkles-skin structure appears to be a universal approach that could be extended to a variety of other film materials. PMID:26310835

  18. Ultra-soft 100 nm thick zero Poisson's ratio film with 60% reversible compressibility

    NASA Astrophysics Data System (ADS)

    Nguyen, Chieu; Szalewski, Steve; Saraf, Ravi

    2013-03-01

    Squeezing films of most solids, liquids and granular materials causes dilation in the lateral dimension which is characterized by a positive Poisson's ratio. Auxetic materials, such as, special foams, crumpled graphite, zeolites, spectrin/actin membrane, and carbon nanotube laminates shrink, i.e., their Poisson's ratio is negative. As a result of Poisson's effect, the force to squeeze an amorphous material, such as a viscous thin film coating adhered to rigid surface increases by over million fold as the thickness decreases from 10 μm to 100 nm due to constrain on lateral deformations and off-plane relaxation. We demonstrate, ultra-soft, 100 nm films of polymer/nanoparticle composite adhered to 1.25 cm diameter glass that can be reversibly squeezed over 60% strain between rigid plates requiring (very) low stresses below 100 KPa. Unlike non-zero Poisson's ratio materials, stiffness decreases with thickness, and the stress distribution is uniform over the film as mapped electro-optically. The high deformability at very low stresses is explained by considering reentrant cellular structure found in cork and the wings of beetles that have Poisson's ratio near zero.

  19. Fracture Mechanism and Toughness Optimization of Macroscopic Thick Graphene Oxide Film

    NASA Astrophysics Data System (ADS)

    Ye, Shibing; Chen, Bin; Feng, Jiachun

    2015-08-01

    Combined high strength and toughness of film materials are rather important for their industrial applications. As a new class of films, graphene oxide films (GOFs) attract intense attention in many applications but are frequently divergent, inconsistent, and poorly reproducible in their mechanical properties. In this study, we first demonstrate that different chemical compositions and assembly structures probably are responsible for the difference in elongations between cast GOFs and filtration GOFs. Comprehensive analysis of the morphologies and mechanical properties indicates that the enhanced elongation of the thick cast GOFs is mainly attributed to the presence of a unique skin-wrinkles-skin structure, which more easily forms in cast GOFs than in filtration counterparts. On the basis of this finding, we attempt to optimize the strength-toughness performance of the cast GOFs by adjusting their structures. With an appropriate thickness of 12.5 μm, the GOFs can achieve an ultrahigh toughness up to 4.37 MJ m-3, which is even comparable to the polymer-toughening graphene/GO-based paper-like materials. Such an optimization of the mechanical properties from the perspective of skin-wrinkles-skin structure appears to be a universal approach that could be extended to a variety of other film materials.

  20. Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates

    PubMed Central

    Behm, R Jürgen

    2014-01-01

    Summary As part of a mechanistic study of the electrooxidation of C1 molecules we have systematically investigated the dissociative adsorption/oxidation of formaldehyde on a polycrystalline Pt film electrode under experimental conditions optimizing the chance for detecting weakly adsorbed reaction intermediates. Employing in situ IR spectroscopy in an attenuated total reflection configuration (ATR-FTIRS) with p-polarized IR radiation to further improve the signal-to-noise ratio, and using low reaction temperatures (3 °C) and deuterium substitution to slow down the reaction kinetics and to stabilize weakly adsorbed reaction intermediates, we could detect an IR absorption band at 1660 cm−1 characteristic for adsorbed formyl intermediates. This assignment is supported by an isotope shift in wave number. Effects of temperature, potential and deuterium substitution on the formation and disappearance of different adsorbed species (COad, adsorbed formate, adsorbed formyl), are monitored and quantified. Consequences on the mechanism for dissociative adsorption and oxidation of formaldehyde are discussed. PMID:24991512

  1. Thin-thick coexistence behavior of 8CB liquid crystalline films on silicon.

    PubMed

    Garcia, R; Subashi, E; Fukuto, M

    2008-05-16

    The wetting behavior of thin films of 4-n-octyl-4'-cyanobiphenyl (8CB) on Si is investigated via optical and x-ray reflectivity measurement. An experimental phase diagram is obtained showing a broad thick-thin coexistence region spanning the bulk isotropic-to-nematic (T(IN)) and the nematic-to-smectic-A (T(NA)) temperatures. For Si surfaces with coverages between 47 and 72 +/- 3 nm, reentrant wetting behavior is observed twice as we increase the temperature, with separate coexistence behaviors near T(IN) and T(NA). For coverages less than 47 nm, however, the two coexistence behaviors merge into a single coexistence region. The observed thin-thick coexistence near the second-order NA transition is not anticipated by any previous theory or experiment. Nevertheless, the behavior of the thin and thick phases within the coexistence regions is consistent with this being an equilibrium phenomenon. PMID:18518487

  2. Effect of adsorbed films on friction of Al2O3-metal systems

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1976-01-01

    The kinetic friction of polycrystalline Al2O3 sliding on Cu, Ni, and Fe in ultrahigh vacuum was studied as a function of the surface chemistry of the metal. Clean metal surfaces were exposed to O2, Cl2, C2H4, and C2H3Cl, and the change in friction due to the adsorbed species was observed. Auger electron spectroscopy assessed the elemental composition of the metal surface. It was found that the systems exposed to Cl2 exhibited low friction, interpreted as the van der Waals force between the Al2O3 and metal chloride. The generation of metal oxide by oxygen exposures resulted in an increase in friction, interpreted as due to strong interfacial bonds established by reaction of metal oxide with Al2O3 to form the complex oxide (spinel). The only effect of C2H4 was to increase the friction of the Fe system, but C2H3Cl exposures decreases friction in both Ni and Fe systems, indicating the dominance of the chlorine over the ethylene complex on the surface

  3. Evaluation of feasibility of measuring EHD film thickness associated with cryogenic fluids. [for space shuttle main engine bearings

    NASA Technical Reports Server (NTRS)

    Kannel, J. W.; Merriman, T. L.; Stockwell, R. D.; Dufrane, K. F.

    1983-01-01

    The feasibility of measuring elastohydrodynamic (EHD) films as formed with a cryogenic (LN2) fluid is evaluated. Modifications were made to an existing twin disk EHD apparatus to allow for disk lubrication with liquid nitrogen. This disk apparatus is equipped with an X-ray system for measuring the thickness of any lubricant film that is formed between the disks. Several film thickness experiments were conducted with the apparatus which indicate that good lubrication films are filmed with LN2. In addition to the film thickness studies, failure analyses of three bearings were conducted. The HPOTP turbine end bearings had experienced axial loads of 36,000 to 44,000 N (8,000 to 10,000 lb). High continuous radial loads were also experienced, which were most likely caused by thermal growth of the inner race. The resulting high internal loads caused race spalling and ball wear to occur.

  4. Thickness effect on the structure, grain size, and local piezoresponse of self-polarized lead lanthanum zirconate titanate thin films

    NASA Astrophysics Data System (ADS)

    Melo, M.; Araújo, E. B.; Shvartsman, V. V.; Shur, V. Ya.; Kholkin, A. L.

    2016-08-01

    Polycrystalline lanthanum lead zirconate titanate (PLZT) thin films were deposited on Pt/TiO2/SiO2/Si substrates to study the effects of the thickness and grain size on their structural and piezoresponse properties at nanoscale. Thinner PLZT films show a slight (100)-orientation tendency that tends to random orientation for the thicker film, while microstrain and crystallite size increases almost linearly with increasing thickness. Piezoresponse force microscopy and autocorrelation function technique were used to demonstrate the existence of local self-polarization effect and to study the thickness dependence of correlation length. The obtained results ruled out the bulk mechanisms and suggest that Schottky barriers near the film-substrate are likely responsible for a build-in electric field in the films. Larger correlation length evidence that this build-in field increases the number of coexisting polarization directions in larger grains leading to an alignment of macrodomains in thinner films.

  5. Effect of film thickness on structural and mechanical properties of AlCrN nanocompoite thin films deposited by reactive DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Prakash, Ravi; Kaur, Davinder

    2016-05-01

    In this study, the influence of film thickness on the structural, surface morphology and mechanical properties of Aluminum chromium nitride (AlCrN) thin films has been successfully investigated. The AlCrN thin films were deposited on silicon (100) substrate using dc magnetron reactive co-sputtering at substrate temperature 400° C. The structural, surface morphology and mechanical properties were studied using X-ray diffraction, field-emission scanning electron microscopy and nanoindentation techniques respectively. The thickness of these thin films was controlled by varying the deposition time therefore increase in deposition time led to increase in film thickness. X-ray diffraction pattern of AlCrN thin films with different deposition time shows the presence of (100) and (200) orientations. The crystallite size varies in the range from 12.5 nm to 36.3 nm with the film thickness due to surface energy minimization with the higher film thickness. The hardness pattern of these AlCrN thin films follows Hall-Petch relation. The highest hardness 23.08 Gpa and young modulus 215.31 Gpa were achieved at lowest grain size of 12.5 nm.

  6. Kosterlitz-Thouless Transition in 4He Films Adsorbed to Rough Calcium Fluoride

    SciTech Connect

    Luhman, D. R.; Hallock, R. B.

    2006-09-07

    Previous measurements in our lab have shown that the onset of superfluidity at the KT transition, typically seen as a sharp change in the frequency of a smooth-surface quartz crystal microbalance, becomes less identifiable in the presence of increasing surface roughness or disorder, while the peak in the dissipation is unchanged. Using a series of microbalances coated with increasingly rough CaF2, we have extended our measurements to lower 4He film coverages and thus lower temperatures. We find at lower 4He coverages that the presence of disorder on the substrate has a diminished effect on the frequency shift.

  7. TFA-MOD (Metal Organic Deposition Using Trifluoroacetates) Films with Thickness Greater Than 1 Micron by a Single Deposition

    NASA Astrophysics Data System (ADS)

    Araki, Takeshi; Hayashi, Mariko; Fuke, Hiroyuki

    The key to obtaining films with thickness greater than 1 micron by a single TFA-MOD deposition is a crack-preventing material. The ratio of fluorine atoms to total fluorine and hydrogen atoms (RF) of the chemical is important for forming excellent superconducting films. Although hydrogen atoms lead to carbon residue, which fatally deteriorates superconducting properties of the resulting film, hydrogen atoms form strong hydrogen bonds with trifluoroacetates and have an excellent crack-prevention effect. The RF range from 0.75 to 0.96 is effective for obtaining single-coated, thick, high-critical-current-density superconducting films.

  8. Influence of calcination ambient and film thickness on the optical and structural properties of sol-gel TiO{sub 2} thin films

    SciTech Connect

    Sreemany, Monjoy . E-mail: m_sreemany@cgcri.res.in; Sen, Suchitra

    2007-01-18

    Influence of both calcination ambient and film thickness on the optical and structural properties of sol-gel derived TiO{sub 2} thin films have been studied. X-ray diffraction results show that prepared films are in an anatase form of TiO{sub 2}. Films calcined in argon or in low vacuum ({approx}2 x 10{sup -1} mbar) are found to be smaller in crystallite size, more transparent at low wavelength region of {approx}300-450 nm, denser, have higher refractive index and band gap energy compared to air-calcined films. Scanning electron microscopic study reveals that surfaces of TiO{sub 2} films calcined in argon or in low vacuum are formed by densely packed nano-sized particulates. Presence of voids and signs of agglomeration can be seen clearly in the surface microstructure of air-calcined films. In the thickness range {approx}200-300 nm, band gap energy and crystallite size of TiO{sub 2} films remain practically unaffected with film thickness but refractive index of thinner film is found to be marginally higher than that of thicker film. In this work, it has been shown that apart from temperature and soaking time, partial pressure of oxygen of the ambient is also an important parameter by which crystallite size, microstructure and optical properties of the TiO{sub 2} films may be tailored during calcination period.

  9. Effects of CdS film thickness on the photovoltaic properties of sintered CdS/CdTe solar cells

    NASA Astrophysics Data System (ADS)

    Lee, J. S.; Jun, Y. K.; Im, H. B.

    1987-01-01

    All polycrystalline CdS/CdTe heterojunction solar cells with various thicknesses of CdS film were prepared by the coating and sintering method in an attempt to optimize the thickness of the sintered CdSfilm whose role is to be the window as well as the front contact for the CdS/CdS/CdTe solar cell. The thickness of the CdS films was varied from 14 to 55 microns by changing the screen mesh size of a screen printer and the solid-liquid ratio of the slurry which consisted of CdS powder, 9 weight percent CdCl2 and propylene glycol. Average grain size of the sintered CdS films increases and porosity decreases with an increase in film thickness. Electrical resistivity of the sintered CdS films shows a minimum value in 35-micron thick film. Highest optical transmission is observed in 20-micron thick CdS film. The CdCl2 remaining in the CdS film after the sintering causes an increase in the thickness of the CdS(1-x)Te(x) solid solution layer, acting as a sintering aid, at the interface between the CdS and the CdTe films. The combination of the optical transmission, the solid solution layer, and the sheet resistance effects resulted in the highest solar efficiency in a CdS/CdTe heterojunction solar cell with 20-micron thick CdS layer.

  10. Friction measurements of nanometer-thick lubricant films using ultra-smooth sliding pins treated with gas cluster ion beam

    NASA Astrophysics Data System (ADS)

    Lu, Renguo; Zhang, Hedong; Mitsuya, Yasunaga; Fukuzawa, Kenji; Itoh, Shintaro

    2013-09-01

    Friction properties of nanometer-thick lubricant films confined between two ultra-smooth solid surfaces are crucial to the practical performance of technologically advanced mechanical devices such as micro-electro-mechanical systems and hard disk drives. In this work, we applied argon gas cluster ion beam (Ar-GCIB) treatments to obtain ultra-smooth sliding pins for pin-on-disk tests of nanometer-thick perfluoropolyether (PFPE) lubricant films coated on magnetic disk surfaces. The GCIB treatments effectively smoothed the pin surfaces, and increases in the Ar dose decreased surface roughness. An ultra-smooth surface with a maximum peak height (Rp) less the monolayer lubricant film thickness was achieved when the Ar dose was increased to 8 × 1016 ions/cm2. We observed that both surface roughness and film thickness affected the friction coefficients of the PFPE films. To quantitatively describe the interplay of surface roughness and film thickness, we introduced two roughness characteristics: the ratio of film thickness to the surface’s root-mean-square roughness (h/σ), and a surface-pattern parameter (γ), defined as the ratio of correlation lengths in two orthogonal directions. We infer that a fixed γ and higher h/σlead to lower friction coefficients, while a fixed h/σand higher γ induce higher friction coefficients.

  11. Ferrimagnetic Tb-Fe Alloy Thin Films: Composition and Thickness Dependence of Magnetic Properties and All-Optical Switching

    NASA Astrophysics Data System (ADS)

    Hebler, Birgit; Hassdenteufel, Alexander; Reinhardt, Patrick; Karl, Helmut; Albrecht, Manfred

    2016-02-01

    Ferrimagnetic rare earth - transition metal Tb-Fe alloy thin films exhibit a variety of different magnetic properties, which depends strongly on composition and temperature. In this study, first the influence of the film thickness (5 - 85 nm) on the sample magnetic properties was investigated in a wide composition range between 15 at.% and 38 at.% of Tb. From our results, we find that the compensation point, remanent magnetization, and magnetic anisotropy of the Tb-Fe films depend not only on the composition but also on the thickness of the magnetic film up to a critical thickness of about 20-30 nm. Beyond this critical thickness, only slight changes in magnetic properties are observed. This behavior can be attributed to a growth-induced modification of the microstructure of the amorphous films, which affects the short range order. As a result, a more collinear alignment of the distributed magnetic moments of Tb along the out-of-plane direction with film thickness is obtained. This increasing contribution of the Tb sublattice magnetization to the total sample magnetization is equivalent to a sample becoming richer in Tb and can be referred to as an “effective” composition. Furthermore, the possibility of all-optical switching, where the magnetization orientation of Tb-Fe can be reversed solely by circularly polarized laser pulses, was analyzed for a broad range of compositions and film thicknesses and correlated to the underlying magnetic properties.

  12. influence of film thickness on optical constants of antimony-based bismuth-doped super-resolution mask layer

    NASA Astrophysics Data System (ADS)

    Lu, Xinmiao; Wu, Yiqun; Wang, Yang; Wei, Jinsong

    As the demand for ultrahigh density information storage continues to grow, recording mark size of several tens nanometer which is smaller than the optical diffraction limit is required in optical memory. Functional film super-resolution technique is one of practical approaches to overcome the optical diffraction limit. Optical constants are important parameters to optical films as super-resolution masks. In this paper, the influence of film thickness on optical constants of antimony-based bismuth-doped super-resolution mask layer is investigated. The structure of the samples with different thickness was studied by X-ray diffraction. The transmission spectrum was measured by spectrophotometry. The optical constants of the films in the range of 300-800 nm were measured by spectroscopic ellipsometry. The results show that the structure of the film transforms from amorphous state to crystal state when the thickness increases from 7 nm to 300 nm. In the range of 300-800 nm, the refractive index and extinction coefficient increase with increasing wavelength. The transmission decreases rapidly when the thickness increases from 7 nm to 30 nm. The influences of film thickness on optical constants are more significant in the thickness range of 7-50 nm than that in the thickness above 50 nm.

  13. The Effects of Two Thick Film Deposition Methods on Tin Dioxide Gas Sensor Performance

    PubMed Central

    Bakrania, Smitesh D.; Wooldridge, Margaret S.

    2009-01-01

    This work demonstrates the variability in performance between SnO2 thick film gas sensors prepared using two types of film deposition methods. SnO2 powders were deposited on sensor platforms with and without the use of binders. Three commonly utilized binder recipes were investigated, and a new binder-less deposition procedure was developed and characterized. The binder recipes yielded sensors with poor film uniformity and poor structural integrity, compared to the binder-less deposition method. Sensor performance at a fixed operating temperature of 330 °C for the different film deposition methods was evaluated by exposure to 500 ppm of the target gas carbon monoxide. A consequence of the poor film structure, large variability and poor signal properties were observed with the sensors fabricated using binders. Specifically, the sensors created using the binder recipes yielded sensor responses that varied widely (e.g., S = 5 – 20), often with hysteresis in the sensor signal. Repeatable and high quality performance was observed for the sensors prepared using the binder-less dispersion-drop method with good sensor response upon exposure to 500 ppm CO (S = 4.0) at an operating temperature of 330 °C, low standard deviation to the sensor response (±0.35) and no signal hysteresis. PMID:22399977

  14. Patterned submicrometer-thick optical polarizing films using stretched silver island multilayers

    NASA Astrophysics Data System (ADS)

    Baba, Kazutaka; Sato, Yoshinori; Yoshitake, Tsutomu; Miyagi, Mitsunobu

    2000-04-01

    We demonstrate a patterned submicrometer-thick optical polarizing film in which non-polarizing areas are formed where the light transmits insensitively to polarization. The polarizing film is fabricated by stretching a silver island multilayer consisting of thin glass layers and silver island layers composed of silver nanoclusters of high density. By stretching the silver island multilayer at a temperature higher than the glass annealing point, the silver islands are elongated along the stretching direction and the large optical anisotropy is induced in the silver island multilayer. In this optical polarizing film, the non- polarizing areas can be easily formed by laser irradiation with high power density as the optical anisotorpy is reduce das the elongated silver islands become spherical ones from the thermal deformation in the irradiated area. We have successfully patterned the optical polarizing films fabricated for the wavelength of 800 nm by laser writing with a 1 W-class carbon dioxide laser. In order to confirm that the optical anisotropy is reduced in the laser written are, the optical characteristics of that area have been measured. In most commercially available optical polarizers including a polarization beam splitter and various polarizing prisms, it is difficult to form the transparent non-polarizing areas. Therefore, the demonstrated patterned optical polarizing films are useful for switchable spatial modulators and filters.

  15. Effect of thickness on structural, optical, electrical and morphological properties of nanocrystalline CdSe thin films for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Purohit, Anuradha; Chander, S.; Nehra, S. P.; Lal, C.; Dhaka, M. S.

    2015-09-01

    This paper presents effect of thickness on the physical properties of thermally evaporated cadmium selenide thin films. The films of thickness 445 nm, 631 nm and 810 nm were deposited employing thermal evaporation technique on glass and ITO coated glass substrates followed by thermal annealing in air atmosphere at temperature 300 °C. The as-deposited and annealed films were subjected to the XRD, UV-Vis spectrophotometer, source meter, SEM and EDS to find the structural, optical, electrical, morphological and compositional analysis respectively. The structural analysis shows that the films have cubic phase with preferred orientation (1 1 1) and nanocrystalline nature. The structural parameters like inter-planner spacing, lattice constant, grain size, number of crystallites per unit area, internal strain, dislocation density and texture coefficient are calculated. The optical band gap is found in the range 1.69-1.84 eV and observed to decrease with thickness. The electrical resistivity is found to increase with thickness for as-deposited films and decrease for annealed films. The morphological studies show that the as-deposited and annealed films are homogeneous, smooth, fully covered and free from crystal defects like pin holes and voids. The grains in the as-deposited films are densely packed, well defined and found to be increased with thickness.

  16. Additive-free thick graphene film as an anode material for flexible lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Rana, Kuldeep; Kim, Seong Dae; Ahn, Jong-Hyun

    2015-04-01

    This work demonstrates a simple route to develop mechanically flexible electrodes for Li-ion batteries (LIBs) that are usable as lightweight effective conducting networks for both cathodes and anodes. Removing electrochemically dead elements, such as binders, conducting agents and metallic current collectors, from the battery components will allow remarkable progress in this area. To investigate the feasibility of using thick, additive-free graphene films as anodes for flexible LIBs, we have synthesized and tested thick, additive-free, freestanding graphene films as anodes, first in a coin cell and further in a flexible full cell. As an anode material in a half cell, it showed a discharge capacity of about 350 mA h g-1 and maintained nearly this capacity over 50 cycles at various current rates. This film was also tested as an anode material in a full cell with a LiCoO2 cathode and showed good electrochemical performance. Because the graphene-based flexible film showed good performance in half- and full coin cells, we used this film as a flexible anode for flexible LIBs. No conducting agent or binder was used in the anode side, which helped in realizing the flexible LIBs. Using this, we demonstrate a thin, lightweight and flexible lithium ion battery with good electrochemical performance in both its flat and bent states.This work demonstrates a simple route to develop mechanically flexible electrodes for Li-ion batteries (LIBs) that are usable as lightweight effective conducting networks for both cathodes and anodes. Removing electrochemically dead elements, such as binders, conducting agents and metallic current collectors, from the battery components will allow remarkable progress in this area. To investigate the feasibility of using thick, additive-free graphene films as anodes for flexible LIBs, we have synthesized and tested thick, additive-free, freestanding graphene films as anodes, first in a coin cell and further in a flexible full cell. As an anode

  17. The synthesis, characterization, and mechanical properties of thick, ultrahard cubic boron nitride films deposited by ion-assisted sputtering

    SciTech Connect

    Mirkarimi, P.B.; Medlin, D.L.; McCarty, K.F.; Dibble, D.C.; Clift, W.M.; Knapp, J.A.; Barbour, J.C.

    1997-08-01

    Significant ion irradiation is needed during growth to synthesize cubic boron nitride (cBN) films. This results in large film stresses, which have limited cBN film thicknesses to only a few hundred nm and represents a significant barrier in the development of cBN film technology. Using a new hybrid deposition technique, we have synthesized cubic BN films up to 700 nm (0.7 {mu}m) thick. A compositional and structural analysis of the films using several standard characterization techniques confirms that relatively thick polycrystalline films with a high cBN content were synthesized. Thicker cBN films enable hardness measurements to be undertaken without major substrate effects. Nanoindentation measurements yield hardness values for the cubic BN films up to 60{endash}70 GPa, which are greater than values measured for bulk cBN. The measured elastic modulus was observed to be lower than the bulk, and this can be accounted for by an elastic deformation of the silicon substrate. The mechanical properties of the cubic BN films are discussed with reference to other ultrahard thin films such as diamond and diamondlike carbon. {copyright} {ital 1997 American Institute of Physics.}

  18. Effects of heat treatment and film thickness on microstructure and critical properties of YBCO film processed by TFA-MOD

    NASA Astrophysics Data System (ADS)

    Jang, Seok Hern; Lim, Jun Hyung; Lee, Jin Sung; Yoon, Kyung Min; Kim, Kyu Tae; Joo, Jinho; Jung, Seung-Boo; Lee, Hoo-Jeong

    2007-01-01

    We fabricated YBCO film on an LAO substrate using the TFA-MOD method and evaluated the effects of the heat treatment temperature and film thickness on the microstructure, degree of texture, and critical properties. The calcining and firing processes were performed in the temperature ranges of 370-460 °C and 750-800 °C, respectively. We found that the phase purity, grain size and orientation, and degree of texture varied with the calcining and firing temperatures. The films fired at 775 °C after calcining at 400-430 °C showed the highest critical temperature (TC-onset) of 89.5 K and critical current (IC) of 40 A/cm-width, which corresponds to a critical current density (JC) of 1.8 MA/cm2. According to the XRD, pole-figure, SEM images, and Raman analysis, these highest critical properties are probably due to the formation of a purer YBCO phase and stronger biaxial texture. In the multi-coated films, the IC value increased from 39 to 169 A/cm-width as the number of coatings increased from one to four, while the corresponding JC was measured to be in the range of 0.8-1.2 MA/cm2. Both the IC and JC decreased when a further coating was applied due to the degradation of the microstructure.

  19. Coherent piezoelectric strain transfer to thick epitaxial ferromagnetic films with large lattice mismatch.

    PubMed

    Kim, Jang-Yong; Yao, Lide; van Dijken, Sebastiaan

    2013-02-27

    Strain control of epitaxial films using piezoelectric substrates has recently attracted significant scientific interest. Despite its potential as a powerful test bed for strain-related physical phenomena and strain-driven electronic, magnetic, and optical technologies, detailed studies on the efficiency and uniformity of piezoelectric strain transfer are scarce. Here, we demonstrate that full and uniform piezoelectric strain transfer to epitaxial films is not limited to systems with small lattice mismatch or limited film thickness. Detailed transmission electron microscopy (TEM) and x-ray diffraction (XRD) measurements of 100 nm thick CoFe(2)O(4) and La(2/3)Sr(1/3)MnO(3) epitaxial films on piezoelectric 0.72Pb(Mg(1/3)Nb(2/3))O(3)-0.28PbTiO(3) substrates (+4.3% and -3.8% lattice mismatch) indicate that misfit dislocations near the interface do not hamper the transfer of piezoelectric strain. Instead, the epitaxial magnetic oxide films and PMN-PT substrates are strained coherently and their lattice parameters change linearly as a function of applied electric field when their remnant growth-induced strain state is negligible. As a result, ferromagnetic properties such as the coercive field, saturation magnetization, and Curie temperature can be reversibly tuned by electrical means. The observation of efficient piezoelectric strain transfer in large-mismatch heteroepitaxial structures opens up new possibilities for the engineering of strain-controlled physical properties in a broad class of hybrid material systems. PMID:23370268

  20. Infrared spectroscopy of water clusters co-adsorbed with hydrogen molecules on a sodium chloride film

    NASA Astrophysics Data System (ADS)

    Yamakawa, Koichiro; Fukutani, Katsuyuki

    2016-06-01

    Hydrogen gas containing a trace of water vapor was dosed on a vacuum-evaporated sodium chloride film at 13 K, and water clusters formed on the substrate were investigated by infrared absorption spectroscopy. Absorption bands due to (H2O)n clusters with n = 3-6 and an induced absorption band due to hydrogen were clearly observed. With increasing gas dosage, the intensities of the cluster bands increased linearly while the intensity of the hydrogen band was constant. This suggests that the water clusters were formed in two-dimensional matrices of hydrogen. We found that the water clusters did exist on the surface upon heating even after the hydrogen molecules had desorbed. A further rise of the substrate temperature up to 27 K yielded the formation of larger clusters, (H2O)n with n > 6 . We also discuss the origins of the two bands of the trimer in terms of pseudorotation and a metastable isomer.

  1. Thickness effect on laser-induced-damage threshold of indium-tin oxide films at 1064 nm

    SciTech Connect

    Wang Haifeng; Huang Zhimeng; Zhang Dayong; Luo Fei; Huang Lixian; Li Yanglong; Luo Yongquan; Wang Weiping; Zhao Xiangjie

    2011-12-01

    Laser-induced-damage characteristics of commercial indium-tin oxide (ITO) films deposited by DC magnetron sputtering deposition on K9 glass substrates as a function of the film thickness have been studied at 1064 nm with a 10 ns laser pulse in the 1-on-1 mode, and the various mechanisms for thickness effect on laser-induced-damage threshold (LIDT) of the film have been discussed in detail. It is observed that laser-damage-resistance of ITO film shows dramatic thickness effect with the LIDT of the 50-nm ITO film 7.6 times as large as the value of 300 nm film, and the effect of depressed carrier density by decreasing the film thickness is demonstrated to be the primary reason. Our experiment findings indicate that searching transparent conductive oxide (TCO) film with low carrier density and high carrier mobility is an efficient technique to improve the laser-damage-resistance of TCO films based on maintaining their well electric conductivity.

  2. The microstructure, optical and electrical property of CdZnTe thick films grown from a CSS method

    NASA Astrophysics Data System (ADS)

    Zhang, Yuelu; Wang, Linjun; Xu, Run; Huang, Jian; Meng, Hua; Tao, Jun; Zhang, Jijun; Min, Jiahua; Shen, Yue

    2015-12-01

    Polycrystalline CdZnTe thick films with an average grain size of 30 μm and thickness of 270 μm were successfully grown on SnO2:F (FTO)-coated glass substrates by close-spaced sublimation method. Electrical properties and UV response of CdZnTe thick films after Br-MeOH etching and ZnCl2 annealing treatment were investigated. By means of the photo-current measurements, the value of mobility-lifetime (μτ) products for CdZnTe films were firstly reported. The results showed that Br-MeOH etching significantly improved UV detection sensitivity of CdZnTe thick films, and made the surface distribution of UV sensitivity more homogeneous. It was also found that a ZnCl2 annealing process did not improve the electrical properties.

  3. Effects of surface roughness and film thickness on the adhesion of a bioinspired nanofilm

    NASA Astrophysics Data System (ADS)

    Peng, Z. L.; Chen, S. H.

    2011-05-01

    Inspired by the gecko's climbing ability, adhesion between an elastic nanofilm with finite length and a rough substrate with sinusoidal roughness is studied in the present paper, considering the effects of substrate roughness and film thickness. It demonstrates that the normal adhesion force of the nanofilm on a rough substrate depends significantly on the geometrical parameters of the substrate. When the film length is larger than the wavelength of the sinusoidal roughness of the substrate, the normal adhesion force decreases with increasing surface roughness, while the normal adhesion force initially decreases then increases if the wavelength of roughness is larger than the film length. This finding is qualitatively consistent with a previously interesting experimental observation in which the adhesion force of the gecko spatula is found to reduce significantly at an intermediate roughness. Furthermore, it is inferred that the gecko may achieve an optimal spatula thickness not only to follow rough surfaces, but also to saturate the adhesion force. The results in this paper may be helpful for understanding how geckos overcome the influence of natural surface roughness and possess such adhesion to support their weights.

  4. Enhanced heat transfer is dependent on thickness of graphene films: the heat dissipation during boiling

    NASA Astrophysics Data System (ADS)

    Ahn, Ho Seon; Kim, Jin Man; Kim, Taejoo; Park, Su Cheong; Kim, Ji Min; Park, Youngjae; Yu, Dong In; Hwang, Kyoung Won; Jo, Hangjin; Park, Hyun Sun; Kim, Hyungdae; Kim, Moo Hwan

    2014-09-01

    Boiling heat transfer (BHT) is a particularly efficient heat transport method because of the latent heat associated with the process. However, the efficiency of BHT decreases significantly with increasing wall temperature when the critical heat flux (CHF) is reached. Graphene has received much recent research attention for applications in thermal engineering due to its large thermal conductivity. In this study, graphene films of various thicknesses were deposited on a heated surface, and enhancements of BHT and CHF were investigated via pool-boiling experiments. In contrast to the well-known surface effects, including improved wettability and liquid spreading due to micron- and nanometer-scale structures, nanometer-scale folded edges of graphene films provided a clue of BHT improvement and only the thermal conductivity of the graphene layer could explain the dependence of the CHF on the thickness. The large thermal conductivity of the graphene films inhibited the formation of hot spots, thereby increasing the CHF. Finally, the provided empirical model could be suitable for prediction of CHF.

  5. Enhanced heat transfer is dependent on thickness of graphene films: the heat dissipation during boiling

    PubMed Central

    Ahn, Ho Seon; Kim, Jin Man; Kim, TaeJoo; Park, Su Cheong; Kim, Ji Min; Park, Youngjae; Yu, Dong In; Hwang, Kyoung Won; Jo, HangJin; Park, Hyun Sun; Kim, Hyungdae; Kim, Moo Hwan

    2014-01-01

    Boiling heat transfer (BHT) is a particularly efficient heat transport method because of the latent heat associated with the process. However, the efficiency of BHT decreases significantly with increasing wall temperature when the critical heat flux (CHF) is reached. Graphene has received much recent research attention for applications in thermal engineering due to its large thermal conductivity. In this study, graphene films of various thicknesses were deposited on a heated surface, and enhancements of BHT and CHF were investigated via pool-boiling experiments. In contrast to the well-known surface effects, including improved wettability and liquid spreading due to micron- and nanometer-scale structures, nanometer-scale folded edges of graphene films provided a clue of BHT improvement and only the thermal conductivity of the graphene layer could explain the dependence of the CHF on the thickness. The large thermal conductivity of the graphene films inhibited the formation of hot spots, thereby increasing the CHF. Finally, the provided empirical model could be suitable for prediction of CHF. PMID:25182076

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

    SciTech Connect

    Rouha, Michael; Cummings, Peter T.

    2014-12-24

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

  7. Facile production of thermoelectric bismuth telluride thick films in the presence of polyvinyl alcohol.

    PubMed

    Lei, C; Burton, M R; Nandhakumar, I S

    2016-06-01

    Bismuth telluride is currently the best performing thermoelectric material for room temperature operations in commercial thermoelectric devices. We report the reproducible and facile production of 600 micron thick bismuth telluride (Bi2Te3) layers by low cost and room temperature pulsed and potentiostatic electrodeposition from a solution containing bismuth and tellurium dioxide in 2 M nitric acid onto nickel in the presence of polyvinyl alcohol (PVA). This was added to the electrolyte to promote thick layer formation and its effect on the structure, morphology and composition of the electrodeposits was investigated by SEM and EDX. Well adherent, uniform, compact and stoichiometric n-type Bi2Te3 films with a high Seebeck coefficient of up to -200 μV K(-1) and a high electrical conductivity of up to 400 S cm(-1) resulting in a power factor of 1.6 × 10(-3) W m(-1) K(-2) at film growth rates of 100 μm h(-1) for potentiostatic electrodeposition were obtained. The films also exhibited a well defined hexagonal structure as determined by XRD. PMID:27166737

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

    DOE PAGESBeta

    Rouha, Michael; Cummings, Peter T.

    2014-12-24

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

  9. Picosecond Dynamics of Shock Compressed and Flash-Heated Nanometer Thick Films of HMX

    NASA Astrophysics Data System (ADS)

    Berg, Christopher; Dlott, Dana

    2013-06-01

    New results are described for probing molecular dynamics of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) subjected to shock compression to a few GPa and/or temperature excursions exceeding thermal decomposition values (T > 500 K). 5-10 nm thick films of δ-HMX were grown on metallic substrates coated with monolayers of 4-nitrothiophenol. Due to shock velocities of a few nm/ps, nanometer thick films allowed picosecond time resolution of shock loading. A plastic polymer layer a few microns in thickness was spin-coated on top of HMX for shock confinement purposes. Both the monolayer and explosive layer were probed utilizing an ultrafast nonlinear coherent vibrational spectroscopy, vibrational sum-frequency generation. Shock compression pressures were estimated via comparison of the monolayer nitro transition frequency shift with static high pressure measurements in a diamond anvil cell. Temperature determinations were based on thermoreflectance measurements of the metallic substrate. Supported by the Stewardship Sciences Academic Alliance Program from the Carnegie-DOE Alliance Center under grant number DOE CIW 4-3253-13 and the US Air Force Office of Scientific Research under award number FAA9550-09-1-0163.

  10. Dynamic mask for producing uniform or graded-thickness thin films

    DOEpatents

    Folta, James A.

    2006-06-13

    A method for producing single layer or multilayer films with high thickness uniformity or thickness gradients. The method utilizes a moving mask which blocks some of the flux from a sputter target or evaporation source before it deposits on a substrate. The velocity and position of the mask is computer controlled to precisely tailor the film thickness distribution. The method is applicable to any type of vapor deposition system, but is particularly useful for ion beam sputter deposition and evaporation deposition; and enables a high degree of uniformity for ion beam deposition, even for near-normal incidence of deposition species, which may be critical for producing low-defect multilayer coatings, such as required for masks for extreme ultraviolet lithography (EUVL). The mask can have a variety of shapes, from a simple solid paddle shape to a larger mask with a shaped hole through which the flux passes. The motion of the mask can be linear or rotational, and the mask can be moved to make single or multiple passes in front of the substrate per layer, and can pass completely or partially across the substrate.

  11. Influence of various thickness metallic interlayers on opto-electric and mechanical properties of AZO thin films on PET substrates

    NASA Astrophysics Data System (ADS)

    Chang, R. C.; Li, T. C.; Lin, C. W.

    2012-02-01

    Various thickness metallic interlayers to improve the opto-electric and mechanical properties of aluminum-doped zinc oxide (AZO) thin films deposited on flexible polyethylene terephtalate (PET) substrates are studied. The effects of the interlayers on the resistance and transmittance of the AZO thin films are discussed. The result shows that the metallic interlayers effectively improve the electric resistance but reduce the optical transmittance of the AZO thin films. These phenomena become more obvious as the interlayer thickness increases. However, the AZO with an aluminum interlayer still behaves an acceptable transmittance. Moreover, mechanical tests indicate that the aluminum interlayer increases the hardness and modulus, and reduce the residual stress of the AZO thin films. In contrast, the silver and copper interlayers decrease the AZO's mechanical properties. Comparing to those without any interlayer, the results show that the best interlayer is the 6 nm thick aluminum film.

  12. Effect of thickness and Ti interlayers on stresses and texture transformations in thin Ag films during thermal cycling

    SciTech Connect

    Baker, Shefford P.; Saha, Krishanu; Shu, Jonathan B.

    2013-11-04

    The driving forces for the (111) to (100) texture transformation often observed during annealing of thin face-centered cubic metal films were investigated. Thin passivated silver films were produced with and without Ti adhesion layers. Stresses were measured in situ during heating to induce the texture transformation, and the texture was characterized using x-ray diffraction. Sufficiently thin films did not transform and sufficiently thick films transformed fully. Intermediate thickness films transformed to an extent dependent on thickness, leading to stable mixed textures. In the prevailing thermodynamic model, texture transformation is attributed to minimization of strain and interface energies. However, calculations using the measured stresses, known elastic constants, and estimated interface energies in this model reveal that the stresses are not sufficient to cause the texture transformation and, furthermore, that variations in interface energy cannot lead to the observed behavior. The results suggest that neither the interface energy nor the stress plays decisive roles in the texture transformation.

  13. Thickness-dependent metal-insulator transition in epitaxial SrRuO3 ultrathin films

    SciTech Connect

    Shen, Xuan; Qiu, Xiangbiao; Su, Dong; Zhou, Shengqiang; Li, Aidong; Wu, Di

    2015-01-06

    Transport characteristics of ultrathin SrRuO₃ films, deposited epitaxially on TiO₂-terminated SrTiO₃ (001) single-crystal substrates, were studied as a function of film thickness. Evolution from a metallic to an insulating behavior is observed as the film thickness decreases from 20 to 4 unit cells. In films thicker than 4 unit cells, the transport behavior obeys the Drude low temperature conductivity with quantum corrections, which can be attributed to weak localization. Fitting the data with 2-dimensional localization model indicates that electron-phonon collisions are the main inelastic relaxation mechanism. In the film of 4 unit cells in thickness, the transport behavior follows variable range hopping model, indicating a strongly localized state. As a result, magnetoresistance measurements reveal a likely magnetic anisotropy with the magnetic easy axis along the out-of-plane direction.

  14. Preparation and photoelectric properties of Fe-doped mesoporous TiO2 thick films used in DSSC

    NASA Astrophysics Data System (ADS)

    Xie, Yian; Shen, Yue; Gu, Feng; Lu, Huina; Wu, Mingming; Wang, Linjun

    2009-08-01

    Fe-doped mesoporous TiO2 (M-TiO2-Fe) thick films were prepared by sol-gel and screen printing process. Raman characteristics results show that the M-TiO2-Fe thick film possesses a certain degree of the anatase phase, which may have advantages on photocatalysis and photovoltaic ability. Derived from small angel X-Ray diffraction (SAXRD), the films exhibit mesoporous structure with pore size around 7-8 nm. Eg of the films was obviously narrowed from 3.4 eV to 3.0 eV, which allows the thick films using more light to initiate photovoltaic process. Dye-sensitized solar cell (DSSC) based on M-TiO2-Fe was structured and chlorophyl was used as sensitizers. The solar cells have an open circuit voltage above 260mV.

  15. David Adler Lectureship Award Talk: Friction and energy dissipation mechanisms in adsorbed molecules and molecularly thin films

    NASA Astrophysics Data System (ADS)

    Krim, Jacqueline

    2015-03-01

    Studies of the fundamental origins of friction have undergone rapid progress in recent years, with the development of new experimental and computational techniques for measuring and simulating friction at atomic length and time scales. The increased interest has sparked a variety of discussions and debates concerning the nature of the atomic-scale and quantum mechanisms that dominate the dissipative process by which mechanical energy is transformed into heat. Measurements of the sliding friction of physisorbed monolayers and bilayers can provide information on the relative contributions of these various dissipative mechanisms. Adsorbed films, whether intentionally applied or present as trace levels of physisorbed contaminants, moreover are ubiquitous at virtually all surfaces. As such, they impact a wide range of applications whose progress depends on precise control and/or knowledge of surface diffusion processes. Examples include nanoscale assembly, directed transport of Brownian particles, material flow through restricted geometries such as graphene membranes and molecular sieves, passivation and edge effects in carbon-based lubricants, and the stability of granular materials associated with frictional and frictionless contacts. Work supported by NSFDMR1310456.

  16. Tribochemical synthesis of nano-lubricant films from adsorbed molecules at sliding solid interface: Tribo-polymers from α-pinene, pinane, and n-decane

    NASA Astrophysics Data System (ADS)

    He, Xin; Barthel, Anthony J.; Kim, Seong H.

    2016-06-01

    The mechanochemical reactions of adsorbed molecules at sliding interfaces were studied for α-pinene (C10H16), pinane (C10H18), and n-decane (C10H22) on a stainless steel substrate surface. During vapor phase lubrication, molecules adsorbed at the sliding interface could be activated by mechanical shear. Under the equilibrium adsorption condition of these molecules, the friction coefficient of sliding steel surfaces was about 0.2 and a polymeric film was tribochemically produced. The synthesis yield of α-pinene tribo-polymers was about twice as much as pinane tribo-polymers. In contrast to these strained bicyclic hydrocarbons, n-decane showed much weaker activity for tribo-polymerization at the same mechanical shear condition. These results suggested that the mechanical shear at tribological interfaces could induce the opening of the strained ring structure of α-pinene and pinane, which leads to polymerization of adsorbed molecules at the sliding track. On a stainless steel surface, such polymerization reactions of adsorbed molecules do not occur under typical surface reaction conditions. The mechanical properties and boundary lubrication efficiency of the produced tribo-polymer films are discussed.

  17. High-mobility three-atom-thick semiconducting films with wafer-scale homogeneity.

    PubMed

    Kang, Kibum; Xie, Saien; Huang, Lujie; Han, Yimo; Huang, Pinshane Y; Mak, Kin Fai; Kim, Cheol-Joo; Muller, David; Park, Jiwoong

    2015-04-30

    The large-scale growth of semiconducting thin films forms the basis of modern electronics and optoelectronics. A decrease in film thickness to the ultimate limit of the atomic, sub-nanometre length scale, a difficult limit for traditional semiconductors (such as Si and GaAs), would bring wide benefits for applications in ultrathin and flexible electronics, photovoltaics and display technology. For this, transition-metal dichalcogenides (TMDs), which can form stable three-atom-thick monolayers, provide ideal semiconducting materials with high electrical carrier mobility, and their large-scale growth on insulating substrates would enable the batch fabrication of atomically thin high-performance transistors and photodetectors on a technologically relevant scale without film transfer. In addition, their unique electronic band structures provide novel ways of enhancing the functionalities of such devices, including the large excitonic effect, bandgap modulation, indirect-to-direct bandgap transition, piezoelectricity and valleytronics. However, the large-scale growth of monolayer TMD films with spatial homogeneity and high electrical performance remains an unsolved challenge. Here we report the preparation of high-mobility 4-inch wafer-scale films of monolayer molybdenum disulphide (MoS2) and tungsten disulphide, grown directly on insulating SiO2 substrates, with excellent spatial homogeneity over the entire films. They are grown with a newly developed, metal-organic chemical vapour deposition technique, and show high electrical performance, including an electron mobility of 30 cm(2) V(-1) s(-1) at room temperature and 114 cm(2) V(-1) s(-1) at 90 K for MoS2, with little dependence on position or channel length. With the use of these films we successfully demonstrate the wafer-scale batch fabrication of high-performance monolayer MoS2 field-effect transistors with a 99% device yield and the multi-level fabrication of vertically stacked transistor devices for three

  18. Influence of the interface on the magnetic properties of ferromagnetic ultrathin films with various adjacent copper thicknesses

    NASA Astrophysics Data System (ADS)

    Zhang, Dong; Jiang, Sheng; Luo, Chen; Wang, Yukun; Rui, Wenbin; Zhai, Ya; Du, Jun; Zhai, Hongru

    2014-05-01

    The interface and magnetic properties of two series of films with Ta(5 nm)/Fe20Ni80Nd0.017(3 nm)/Cu(t nm) and Ta(5 nm)/Cu(t nm)/Fe50Co50Gd0.07(3 nm)/Cu(2 nm) structures have been investigated by atomic force microscopy, vibrating sample magnetometer, and ferromagnetic resonance (FMR). The roughness of all films increases with increasing copper thickness, which causes the different grain sizes in the surface of films. The coercivity of FeCo-Gd films increases with increasing thickness of inserted Cu layer while decreases with increasing thickness of Cu capping layer for FeNi-Nd films. FMR linewidth exhibits huge dependence on the thickness of inserted Cu layer for FeCo-Gd films, increasing from 2270 to 3680 Oe, which comes from the additional contribution of effect of the two-magnon scattering. And the thickness of Cu capping layer shows also an influence on FMR linewidth of FeNi-Nd films, increasing from 190 to 320 Oe, which mainly comes from intrinsic FMR linewidth and plus minor inhomogeneous broadening. All of these extrinsic linewidth broadening are related to the interface roughness.

  19. Lead zirconate titanate-based thick films for high-frequency focused ultrasound transducers prepared by electrophoretic deposition.

    PubMed

    Abellard, André-Pierre; Kuscer, Danjela; Grégoire, Jean-Marc; Lethiecq, Marc; Malic, Barbara; Levassort, Franck

    2014-03-01

    An electrophoretic deposition (EPD) process with high deposition rate was used to fabricate a curved piezoelectric thick film devoted to high-frequency transducers for medical imaging. Niobium-doped lead zirconate titanate (PZTNb) powder was stabilized in ethanol to prepare a suspension with high zeta potential and low conductivity. A gold layer, pad-printed and fired on a curved porous PZT substrate, was used as the working electrode for the deposition of the PZTNb thick film. This substrate was chosen because it has the required properties (acoustic impedance and attenuation) to be used directly as a backing for the high-frequency transducer, leading to a simplified process for transducer assembly with this integrated structure. PZT-Nb thick films were also deposited by EPD on flat gold-coated alumina substrates as a reference. The thickness of the films was between 20 and 35 μm, and their electromechanical performance was comparable to standard PZT bulk ceramics with a thickness coupling factor of 48%. For the curved thick film, the thickness coupling factor was slightly lower. The corresponding integrated structure was used to fabricate a transducer with a center frequency of 40 MHz and an f-number of 2.8. It was integrated into a realtime ultrasound scanner and used to image human forearm skin; the resulting images showed, for the first time, the efficacy of the EPD process for these imaging applications. PMID:24569258

  20. High quality MgB2 thick films and large-area films fabricated by hybrid physical chemical vapor deposition with a pocket heater

    NASA Astrophysics Data System (ADS)

    Wang, S. F.; Chen, Ke; Lee, C.-H.; Soukiassian, A.; Lamborn, D. R.; DeFrain, R.; Redwing, J. M.; Li, Qi; Schlom, D. G.; Xi, X. X.

    2008-08-01

    A hybrid physical-chemical vapor deposition process using a pocket heater was developed for the growth of high quality epitaxial large-area MgB2 thin films and c-axis textured MgB2 thick films. This technique is able to independently control the substrate and Mg source temperatures and maintain sufficient Mg overpressure to ensure phase stability. The two-inch large-area MgB2 thin films showed uniform superconducting properties with the superconducting transition temperature Tc of about 40 K, residual resistivity ratio (RRR) of about 10, and critical current density Jc of about 107 A cm-2 (0 T, 5 K). The thick films (~10 µm) on sapphire substrates showed a maximum Tc of 40 K and RRR of 15, and a Jc of 1.6 × 106 A cm-2 at low applied magnetic fields even at 20 K. High quality thick films also have been obtained on metal substrates.

  1. Impedance of nanometer thickness ferromagnetic Co40Fe40B20 films

    NASA Astrophysics Data System (ADS)

    Jen, Shien Uang; Chou, Tzu Yang; Lo, Chi Kuen

    2011-07-01

    Nanocrystalline Co40Fe40B20 films, with film thickness t f = 100 nm, were deposited on glass substrates by the magnetron sputtering method at room temperature. During the film deposition period, a dc magnetic field, h = 40 Oe, was applied to introduce an easy axis for each film sample: one with h|| L and the other with h|| w, where L and w are the length and width of the film. Ferromagnetic resonance (FMR), ultrahigh frequency impedance (IM), dc electrical resistivity ( ρ), and magnetic hysteresis loops (MHL) of these films were studied. From the MHL and r measurements, we obtain saturation magnetization 4 πM s = 15.5 kG, anisotropy field H k = 0.031 kG, and r = 168 mW.cm. From FMR, we can determine the Kittel mode ferromagnetic resonance (FMR-K) frequency f FMRK = 1,963 MHz. In the h|| L case, IM spectra show the quasi-Kittel-mode ferromagnetic resonance (QFMR-K) at f 0 and the Walker-mode ferromagnetic resonance (FMR-W) at f n , where n = 1, 2, 3, and 4. In the h|| w case, IM spectra show QFMR-K at F 0 and FMR-W at F n . We find that f 0 and F 0 are shifted from f FMRK, respectively, and f n = F n . The in-plane spin-wave resonances are responsible for those relative shifts. PACS No. 76.50.+q; 84.37.+q; 75.70.-i

  2. Quasiparticle Transport in Thick Aluminum Films Coupled to Tungsten Transition Edge Sensors

    NASA Astrophysics Data System (ADS)

    Yen, J. J.; Kreikebaum, J. M.; Young, B. A.; Cabrera, B.; Moffatt, R.; Redl, P.; Shank, B.; Brink, P. L.; Cherry, M.; Tomada, A.

    2016-07-01

    We have fabricated and characterized test devices of a new geometry for cryogenic dark matter search superconducting sensors. The modified design uses the same photolithography masks used to fabricate earlier-generation devices, but with the Al and W films deposited in reverse order. This inverted film geometry (Al over W instead of our conventional W over Al) offers a simplified and robust way to dramatically increase the thickness of Al energy-collecting fins coupled to thin W-TESs—tungsten-transition edge sensors. Data are presented from experiments with inverted geometry test devices exposed to X-rays from a NaCl fluorescence source. The results are compared to data obtained with similar devices fabricated in the standard, non-inverted geometry.

  3. Thickness dependence of resistivity for Cu films deposited by ion beam deposition

    NASA Astrophysics Data System (ADS)

    Lim, J.-W.; Mimura, K.; Isshiki, M.

    2003-07-01

    The thickness dependence of the resistivity for Cu films deposited by ion beam deposition (IBD) was evaluated using Fuchs-Sondheimer (F-S) model for electron surface scattering and Mayadas-Shatzkes (M-S) model for electron grain boundary scattering. For fitting the F-S and M-S models to the experimental data, the approximate equations proposed in both models were discussed and it was confirmed that the experimental resistivity of the Cu films could be described well by a simple form combined of the approximate equations for both models. By means of the simple form in this work, the most reasonable fit to the experimental data could be obtained under the conditions of the surface scattering coefficient p=0 and the reflection coefficient at grain boundary R=0.40.

  4. A Simple and Facile Iodination Method for Improving Sinterability and Electrical Conductivity of Silver Thick Films

    NASA Astrophysics Data System (ADS)

    Zhou, Jian; Gan, Weiping; Li, Yingfen; Luo, Lin; Pan, Qiaoyun; Xiong, Zhijun

    2014-09-01

    Micro-sized silver powders were decorated with nano-scaled Ag/AgI clusters on the surface via a simple reaction with iodine and subsequent exposure to sunshine. Surface morphologies, crystal structures, and thermal properties of the powders were characterized. The powders with different mole ratios of I:Ag (0:100, 2:100, 10:100) were employed in silver pastes to evaluate sinterability and electrical conductivity of thick films. Microstructures and sheet resistance of the films were investigated by scanning electron microscopy and the four-point probe method. The particles coated with and without nano-sized Ag/AgI clusters showed different sintering behaviors. Moreover, clear necks were formed between the Ag particles with the ratio of 2:100 even at 570°C, whereas those untreated remained discrete. However, over-decoration lowered sinterability and electrical conductivity.

  5. 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.

  6. The role of the stagnant-film thickness in mesoscopic modeling of equiaxed grain envelopes

    NASA Astrophysics Data System (ADS)

    Souhar, Youssef; De Felice, Valerio F.; Založnik, Miha; Combeau, Hervé; Beckermann, Christoph

    2016-03-01

    The mesoscopic envelope model overcomes the limitations of phase-field methods. It can be applied at larger scales and can include fluid flow at reasonable computing cost. It consists of the description of a dendritic grain by an envelope that links the active dendrite branches. The grain is modelled as an evolving porous medium and the liquid-solid phase change and solute transport are modelled by volume-averaged equations. The velocities of the dendrite tips are determined by the local solute-concentration field in the proximity of the envelope through an analytical stagnant-film model. In this publication, we present our implementation of the model for a binary alloy and we discuss the influence of the stagnant-film thickness, the principal model parameter, on the predicted 3D equiaxed grains by comparisons with the scaling laws for binary-alloy dendrites obtained in recent experiments by Melendez and Beckermann.

  7. Wet Chemical Synthesis and Screening of Thick Porous Oxide Films for Resistive Gas Sensing Applications

    PubMed Central

    Frenzer, Gerald; Frantzen, Andreas; Sanders, Daniel; Simon, Ulrich; Maier, Wilhelm F.

    2006-01-01

    A method of wet chemical synthesis suitable for high throughput and combinatorial applications has been developed for the synthesis of porous resistive thick-film gas sensors. This method is based on the robot-controlled application of unstable metal oxide suspensions on an array of 64 inter-digital electrodes positioned on an Al2O3 substrate. SnO2, WO3, ZrO2, TiO2, CeO2, In2O3 and Bi2O3 were chosen as base oxides, and were optimised by doping or mixed oxide formation. The parallel synthesis of mixed oxide sensors is illustrated by representative examples. The electrical characteristics and the sensor performance of the films were measured by high-throughput impedance spectroscopy while supplying various test gases (H2, CO, NO, NO2, propene). Data collection, data mining techniques applied and the best potential sensor materials discovered are presented.

  8. Thermal Marangoni instability of a thin film flowing down a thick wall deformed in the backside

    NASA Astrophysics Data System (ADS)

    Dávalos-Orozco, L. A.

    2016-05-01

    The nonlinear instability of a thin liquid film flowing down a heated thick wall with deformations in the backside is investigated. Here it is assumed that the wall deformations are sinusoidal in space. Time dependent perturbations are imposed at the origin of the free surface of the film. It is found that the wall deformations have an important influence on the flow instability. Moreover, it is shown that the free surface has a large amplitude spatial response to the backside deformations of the wall. This response increases its amplitude considerably when decreasing the wall spatial wavelength down to the wavelength of the time dependent perturbations. At that point, numerical analysis reveals that the time dependent perturbations in some cases are almost impossible to observe on the free surface response. However, in other cases, their interaction produces large amplitude nonlinear wave modulations.

  9. Thick optical films for the conduction of optical and infrared radiation

    SciTech Connect

    Bain, C.N.; Gordon, B.A.; Knasel, T.M.; Malinowski, R.L.

    1981-01-01

    Experimental results are presented for the characteristics of thick optical films, which can be used to direct and conduct optical and IR radiation, for the case of light concentration onto solar cells. Incident light is trapped within a thin, flat sheet of transparent material by a diffuse selective surface on the back of the transparent layer, and so directed that total internal reflection occurs, with some of the captured light finding its way back to the photovoltaic cells attached to the back of the layer. A Monte Carlo computer model is used to analyze this system, whose achievable gain depends on layer thickness, trapping material refraction index, and solar cell shape and size. Results indicate that gains of a factor of two in power output are obtainable for the case of sparsely-packed solar cell arrays and lower factors for more densely-packed arrays.

  10. Thickness and Temperature effect on tip induced polarization switching of Ni substituted PZT Thin Films

    NASA Astrophysics Data System (ADS)

    Kumari, Shalini; Pradhan, Dhiren; Vasudevan, Rama; Strelcove, Eveghni; Ortega, Nora; Kumar, Ashok; Kalinin, Sergei; Katiyar, Ram

    Piezoresponse force microscopy (PFM) is one of the most popular techniques used for the complex investigations of the ferroelectric materials, allowing visualization of the static ferroelectric domain structures. Substitution of Ni in B site of PZT has been chosen for the present study to reduce the optical band gap for phototovoltaic applications. Here we experimentally studied the effect of thickness and temperature on tip induced polarization reversal of Ni doped PZT thin films by band excitation PFM. The out of field and in field band excitation polarization spectroscopy along with poling experiment conclusively confirm the existence of ferroelectricity down to 5 nm. The decrease of piezoresponse is observed with increase of temperature. The ferroelectric phase transition is also probed by the temperature dependence of piezoresponse studies. Detailed studies on effect of thickness and temperature on coercive field, imprint, switchable polarization, nucleation bias of PZTNi30 will be discussed in the meeting.

  11. Oil film thickness using airborne laser-induced oil fluorescence backscatter

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.

    1983-01-01

    Remote airborne measurement of oil film thickness on ocean surface using laser-induced water Raman backscatter is discussed. It is pointed out that the theoretical model of oil fluorescence by Horvath et al. (1971) contains the necessary constituents to provide for the natural background fluorescence that is also induced by the laser during the course of an oil thickness experiment. How the various parameters of the model are obtained from typical airborne profile data is discussed, and it is shown that the water Raman backscatter may be used to assist further in the application of the data. The regions or water types over which the technique might be most useful or applicable are discussed.

  12. Nanomechanical testing of circular freestanding polymer films with sub-micron thickness

    SciTech Connect

    Maner, Kyle C.; Begley, Matthew R. . E-mail: begley@virgina.edu; Oliver, Warren C.

    2004-11-08

    This paper describes techniques to create freestanding films over perfectly circular spans (windows) and measure their mechanical properties using instrumented nanoindentation. Test samples were created by spin-casting polymer films over glass plates with embedded fibers, which were subsequently etched using a relatively weak acid to leave freestanding circular spans. The freestanding spans were tested using an instrumented nanoindenter over a wide range of applied loads and displacements. Material properties can be extracted from measured load-deflection responses using straightforward models for point-loads on circular plates or membranes. Results are presented for poly(methyl methacrylate) and poly(2,6,dimethyl,1,4,phenylene ether) films with thickness ranging from 350 to 750 nm. The properties derived from freestanding tests are compared with traditional nanoindentation of films on intact substrates. The freestanding approach has key advantages for characterizing micron-scale behavior of compliant materials, notably greater ease and applicability of sample preparation over other micro-fabrication techniques and straightforward analytical or numerical models.

  13. Alcohol vapor sensing by cadmium-doped zinc oxide thick films based chemical sensor

    NASA Astrophysics Data System (ADS)

    Zargar, R. A.; Arora, M.; Chackrabarti, S.; Ahmad, S.; Kumar, J.; Hafiz, A. K.

    2016-04-01

    Cadmium-doped zinc oxide nanoparticles were derived by simple chemical co-precipitation route using zinc acetate dihydrate and cadmium acetate dihydrate as precursor materials. The thick films were casted from chemical co-precipitation route prepared nanoparticles by economic facile screen printing method. The structural, morphological, optical and electrical properties of the film were characterized relevant to alcohol vapor sensing application by powder XRD, SEM, UV-VIS and DC conductivity techniques. The response and sensitivity of alcohol (ethanol) vapor sensor are obtained from the recovery curves at optimum working temperature range from 20∘C to 50∘C. The result shows that maximum sensitivity of the sensor is observed at 25∘C operating temperature. On varying alcohol vapor concentration, minor variation in resistance has been observed. The sensing mechanism of sensor has been described in terms of physical adsorption and chemical absorption of alcohol vapors on cadmium-doped zinc oxide film surface and inside film lattice network through weak hydrogen bonding, respectively.

  14. Homobuffer thickness effect on the conduction type of non-polar ZnO thin films

    NASA Astrophysics Data System (ADS)

    Pan, X. H.; Ding, P.; Huang, J. Y.; He, H. P.; Ye, Z. Z.; Lu, B.

    2014-10-01

    Non-polar (101bar0) ZnO thin films were epitaxially grown on m-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The homobuffer thickness effect on the conduction type of undoped ZnO thin films is carefully investigated. With a relatively thicker buffer layer, weak p-type conductivity with a hole concentration of 1.6×1016 cm-3, a Hall mobility of 0.33 cm2 V-1 s-1, and a resistivity of 1.2×103 Ω cm are achieved for the film. By careful analysis of results from low temperature photoluminescence and transmission electron microscopy measurements, a correlation of the 3.32-eV emission to the p-type conductivity in the undoped non-polar ZnO films is revealed and discussed. The results are important to help deepen understanding of the origin of p-type behavior in ZnO-based materials.

  15. A low-cost photovoltaic cell process based on thick film techniques

    NASA Technical Reports Server (NTRS)

    Mardesich, N.; Pepe, A.; Bunyan, S.; Edwards, B.; Olson, C.

    1980-01-01

    The low-cost, easily automated processing for solar cell fabrication being developed at Spectrolab for the DOE LSA program is described. These processes include plasma-etching, spray-on diffusion sources and antireflective coating, thick film metallization, aluminum back contacts, laser scribing and ultrasonic soldering. The process sequence has been shown to produce solar cells having 15% conversion efficiency at AM1 which meet the cell fabrication budget required for the DOE 1986 cost goal of $0.70 per peak watt in 1980.

  16. Evaluation of eddy-current proximity devices for measuring thin potassium film thicknesses

    NASA Technical Reports Server (NTRS)

    Asadourian, A. S.

    1972-01-01

    Two eddy current proximity probe systems were tested over a range of 0 to 508 micrometers (0 to 20 mils) of simulated potassium film thicknesses for simulated temperatures of 66 C (150 F), 232 C (450 F), and 666 C (1230 F). The results of short time calibration tests are presented. Instrument drift was a problem throughout the testing and, without correction, may limit the use of such systems to short periods of time. Additional development will be required prior to their being usable as practical instrumentation systems.

  17. Elastohydrodynamic film thickness measurements of artificially produced surface dents and grooves. [using optical interferometry

    NASA Technical Reports Server (NTRS)

    Wedeven, L. D.; Cusano, C.

    1978-01-01

    Elastohydrodynamic (EHD) film thickness measurements using optical interferometry were made of artificially produced dents and grooves under rolling and sliding conditions. These measurements are compared to stylus traces of the dent and groove profiles to determine the local deformation associated with micro-EHD pressure generation. The surface geometry associated with the dents and grooves became intimately involved in the lubrication process itself, creating local pressure variations that substantially deformed the local surface geometry, particularly under sliding conditions. The rolling results implied surface initiated fatigue, and the sliding results showed clearly the EHD surface interactions that must occur prior to scuffing failure.

  18. Elastohydrodynamic film thickness measurements of artificially produced surface dents and grooves. [on fatigue failure of bearings

    NASA Technical Reports Server (NTRS)

    Wedeven, L. D.; Cusano, C.

    1978-01-01

    Elastohydrodynamic (EHD) film thickness measurements using optical interferometry have been made of artificially produced dents and grooves under rolling and sliding conditions. These measurements are compared to stylus traces of the dent and groove profiles to determine the local deformation associated with micro-EHD pressure generation. The surface geometry associated with the dents and grooves is seen to become intimately involved in the lubrication process itself, creating local pressure variations that substantially deform the local surface geometry, particularly under sliding conditions. The rolling results have implications concerning surface initiated fatigue and the sliding results show clearly the EHD surface interactions that must occur prior to scuffing failure.

  19. Influence of film thickness and air exposure on the transport gap of manganese phthalocyanine

    SciTech Connect

    Haidu, F.; Fechner, A.; Salvan, G.; Gordan, O. D.; Fronk, M.; Zahn, D. R. T.; Lehmann, D.; Mahns, B.; Knupfer, M.

    2013-06-15

    The interface formation between manganese phthalocyanine (MnPc) and cobalt was investigated combining ultraviolet photoelectron spectroscopy and inverse photoelectron spectroscopy. The transport band gap of the MnPc increases with the film thickness up to a value of (1.2 {+-} 0.3) eV while the optical band gap as determined from spectroscopic ellipsometry amounts to 0.5 eV. The gap values are smaller compared to other phthalocyanines due to metallic Mn 3d states close to the Fermi level. The transport band gap was found to open upon air exposure as a result of the disappearance of the occupied 3d electronic states.

  20. Solid state microelectronics tolerant to radiation and high temperature. [JFET thick film hybrids

    NASA Technical Reports Server (NTRS)

    Draper, B. L.; Palmer, D. W.

    1981-01-01

    The 300 C electronics technology based on JFET thick film hybrids was tested up to 10 to the 9th power rad gamma (Si) and 10 to the 15th power neutrons/sq cm. Circuits and individual components from this technology all survived this total dose although some devices required 1 hour of annealing at 200 or 300 C to regain functionality. This technology used with real time annealing should function to levels greater than 10 to the 10th power rad gamma and 10 to the 16th power n/sq cm.

  1. Determination of lubricant selection based on elastohydrodynamic film thickness and traction measurement

    NASA Technical Reports Server (NTRS)

    Dow, T. A.; Kannel, J. W.

    1979-01-01

    The project was conducted to aid in the development of an elastohydrodynamic specification for military lubricants. Experiments were conducted with a rolling disk apparatus designed to simulate a bearing or gear type contact. Measurements included lubricant film thickness, lubricant breakdown and traction for a range of loads, speeds, temperatures, and surface roughnesses. Several lubricants were used in the investigations including a traction fluid, two synthetic paraffinic lubricants and several lubricants conforming to MIL-L 7808 and 23699 specifications. Recommendations regarding an EHD specification are included.

  2. 275/sup 0/C thick-film hybrid microcircuitry fabrication technology

    SciTech Connect

    Bonn, P.A.; Palmer, D.W.

    1980-07-01

    High-temperature electronics is needed for geothermal well-logging tools, jet engine monitors, nuclear reactor instruments, and fossil fuel exploration and production systems. The step-by-step fabrication technology of thick-film hybrids useful for at least 1000 hours at 275/sup 0/C is described. Hybrid technology, qualified to standard military specifications, was modified both in materials and fabrication processes to achieve this high-temperature operation. In addition to documenting this Sandia-developed technology, various alternate approaches are described to increase the versatility and applicability of these methods.

  3. Deep Impact Delta II Launch Vehicle Cracked Thick Film Coating on Electronic Packages Technical Consultation Report

    NASA Technical Reports Server (NTRS)

    Cameron, Kenneth D.; Kichak, Robert A.; Piascik, Robert S.; Leidecker, Henning W.; Wilson, Timmy R.

    2009-01-01

    The Deep Impact spacecraft was launched on a Boeing Delta II rocket from Cape Canaveral Air Force Station (CCAFS) on January 12, 2005. Prior to the launch, the Director of the Office of Safety and Mission Assurance (OS&MA) requested the NASA Engineering and Safety Center (NESC) lead a team to render an independent opinion on the rationale for flight and the risk code assignments for the hazard of cracked Thick Film Assemblies (TFAs) in the E-packages of the Delta II launch vehicle for the Deep Impact Mission. The results of the evaluation are contained in this report.

  4. A study of the factors effecting layer thickness uniformity and layer breakup in microlayered coextruded films

    NASA Astrophysics Data System (ADS)

    Ghumman, Bhavjit Singh

    Microlayer coextrusion offers the opportunity to economically commercialize the production of nanometer thick film. A major obstacle towards commercialization is the non-uniform thickness of these layers and their breakup into droplets, which is also known as a scattering instability. Prior research had indicated a strong interaction between material properties and process parameters. Therefore, the focus of this research effort was to better understand and then identify the coextrusion parameters and material properties that governed the layer non-uniformity and scattering. Initial studies had indicated that there existed an interaction between the two extruders, which gave rise to pressure fluctuations and non-uniform flow. The interaction of the two extruders was studied by analyzing the pressure signals at the two extruders and the junction of the two streams. A response surface method was used to analyze the two extruders individually, the number of layer multiplying elements and finally the interaction between the two extruders and the effect they had on pressure, surging, flow rate and torque. Although the interaction of the two extruders did result in higher backpressures, it did not decrease the output. The output was independent of the screw speed of the other extruder, however it did influence the melting mechanics along the screw. The more shear sensitive PMMA showed a greater degree of sensitivity than the Newtonian PC. The influence of primary; coextrusion, and secondary; chill roll, processing on the final layer thickness was studied in a second set of experiments. For this purpose primary coextrusion process parameters such as screw speed ratio, die temperature and core melt temperature were changed and the effect on the layer thickness uniformity was studied. Similarly secondary process parameters such as nip gap and chill roll speed were also investigated. Thickness was measured using an Atomic Force Microscope (AFM). The screw speed ratio was the

  5. Nanostructured MgTiO3 thick films obtained by electrophoretic deposition from nanopowders prepared by solar PVD

    NASA Astrophysics Data System (ADS)

    Apostol, Irina; Mahajan, Amit; Monty, Claude J. A.; Venkata Saravanan, K.

    2015-12-01

    A novel combination of solar physical vapor deposition (SPVD) and electrophoretic deposition (EPD) that was developed to grow MgTiO3 nanostructured thick films is presented. Obtaining nanostructured MgTiO3 thick films, which can replace bulk ceramic components, a major trend in electronic industry, is the main objective of this work. The advantage of SPVD is direct synthesis of nanopowders, while EPD is simple, fast and inexpensive technique for preparing thick films. SPVD technique was developed at CNRS-PROMES Laboratory, Odeillo-Font Romeu, France, while the EPD was performed at University of Aveiro - DeMAC/CICECO, Portugal. The nanopowders with an average crystallite size of about 30 nm prepared by SPVD were dispersed in 50 ml of acetone in basic media with addition of triethanolamine. The obtained well-dispersed and stable suspensions were used for carrying out EPD on 25 μm thick platinum foils. After deposition, films with thickness of about 22-25 μm were sintered in air for 15 min at 800, 900 and 1000 °C. The structural and microstructural characterization of the sintered thick films was carried out using XRD and SEM, respectively. The thickness of the sintered samples were about 18-20 μm, which was determined by cross-sectional SEM. Films sintered at 900 °C exhibit a dielectric constant, ɛr ∼18.3 and dielectric loss, tan δ ∼0.0012 at 1 MHz. The effects of processing techniques (SPVD and EPD) on the structure, microstructure and dielectric properties are reported in detail. The obtained results indicate that the thick films obtained in the present study can be promising for low loss materials for microwave and millimeter wave applications.

  6. From adsorption to condensation: the role of adsorbed molecular clusters.

    PubMed

    Yaghoubian, Sima; Zandavi, Seyed Hadi; Ward, C A

    2016-08-01

    The adsorption of heptane vapour on a smooth silicon substrate with a lower temperature than the vapour is examined analytically and experimentally. An expression for the amount adsorbed under steady state conditions is derived from the molecular cluster model of the adsorbate that is similar to the one used to derive the equilibrium Zeta adsorption isotherm. The amount adsorbed in each of a series of steady experiments is measured using a UV-vis interferometer, and gives strong support to the amount predicted to be adsorbed. The cluster distribution is used to predict the subcooling temperature required for the adsorbed vapour to make a disorder-order phase transition to become an adsorbed liquid, and the subcooling temperature is found to be 2.7 ± 0.4 K. The continuum approach for predicting the thickness of the adsorbed liquid film originally developed by Nusselt is compared with that measured and is found to over-predict the thickness by three-orders of magnitude. PMID:27426944

  7. Structural investigation of edible zein films/coatings and directly determining their thickness by FT-Raman spectroscopy.

    PubMed

    Hsu, Bao-Lian; Weng, Yih-Ming; Liao, Yu-Hsiu; Chen, Wenlung

    2005-06-29

    Near-infrared Fourier transform Raman (FT-Raman) spectroscopy was employed to study the molecular structure of edible zein films/coatings, which were fabricated directly from zein protein. The secondary structure of zein protein was mainly in alpha-helix and remained unaltered during film formation as evidenced by the vibrational modes of amide I at 1656 cm(-1) and amide III at 1274 cm(-1). Raman results indicated that hydrophobic interaction played an important role in the formation of zein film and disulfide bonding might be responsible for the structural stability of zein protein during film formation. To enhance its antimicrobial property, an antimicrobial zein film was manufactured by incorporating zein protein with benzoic acid whose structure was then characterized by FT-Raman. It showed that physical entrapment or hydrophobic interaction was crucial to the incorporation of benzoic acid with zein protein, and the secondary structure of the antimicrobial film was still maintained in alpha-helical form. In addition, FT-Raman exhibits its preference in directly determining the thickness of zein films/coatings. By correlating the Raman intensity ratio of nu(1003) to nu(84) (I(1003/84)) versus the thickness of zein film, a linear relationship with high coefficient (R(2) = 0.9927) was obtained, which was then used pragmatically to determine the thickness of zein coatings on apple. It showed that the FT-Raman result (thickness = 0.27 +/- 0.01 mm) was consistent with that of classical micrometric measurement (thickness = 0.28 +/- 0.02 mm). Consequently, FT-Raman provides a direct, simple, and reagent-free method to characterize the structure and the thickness of zein films/coatings. PMID:15969480

  8. Effects of total thickness on (001) texture, surface morphology, and magnetic properties of [Fe/Pt]{sub n} multilayer films by monatomic layer deposition

    SciTech Connect

    Yu, Y. S.; George, T. A.; Yue, L. P.; Sellmyer, D. J.; Li, W. L.; Fei, W. D.; Li Haibo; Liu Mei

    2010-10-15

    Atomic-scale [Fe/Pt]{sub n} multilayer films with different total thickness were prepared on thermally oxidized Si (100) substrates at room temperature by monatomic layer deposition using dc-magnetron and rf-magnetron sputtering. Effects of the total thickness on (001) texture, surface morphology, and magnetic properties of the postannealed films have been investigated. It is found that the particlelike structure films with perfect (001) texture and perpendicular magnetic anisotropy are obtained with a thickness of less than or equal to 6.5 nm. After 500 deg. C annealing, the films with thickness of 6.5 and 11.9 nm show very smooth surface. In addition, with increasing total thickness of the films, (001) texture and perpendicular magnetic anisotropy of the annealed films deteriorate, and the films become continuous in structure. The total thickness of the films also affects the exchange-coupling interaction among FePt magnetic grains and the magnetization reversal process.

  9. Effects of molecule-insulator interaction on geometric property of a single phthalocyanine molecule adsorbed on an ultrathin NaCl film

    NASA Astrophysics Data System (ADS)

    Miwa, Kuniyuki; Imada, Hiroshi; Kawahara, Shota; Kim, Yousoo

    2016-04-01

    The adsorption structure and orientation of a metal-free phthalocyanine (H2Pc ) and a magnesium phthalocyanine (MgPc) on a bilayer of NaCl films were investigated both theoretically and experimentally by means of first-principles calculations based on density functional theory and by scanning tunneling microscopy. H2Pc is adsorbed with its center over the sodium cation, and H-N bonds in the molecule are aligned with the [100] or [010] surface direction of a bilayer (001)-terminated NaCl film. The most stable structures of MgPc on the NaCl film show two kinds of orientations corresponding to the molecule rotated by ±7∘ relative to the [110] surface direction, with the Mg cation positioned over the chlorine anion in both cases. The energetic barrier for switching between these orientations is as low as 9.0 meV, and during an STM measurement, an orientational change of MgPc can be observed. The interaction between the adsorbed molecule and the NaCl film were analyzed in terms of dispersion interaction, Mg-Cl chemical bonding, and electrostatic interaction. It is found that the small electrostatic interaction between the molecule and the film gives a dominant contribution to determining the molecular orientation. Our detailed and comprehensive studies of the molecule-insulator interaction will provide knowledge to understand and control the properties of molecules on an insulating material.

  10. Fabrication of TiO2 Thick Film for Photocatalyst from Commercial TiO2 Powder

    NASA Astrophysics Data System (ADS)

    Asteti, S. Fuji; Syarif, D. Gustaman

    2008-03-01

    Photocatalytic activity of TiO2 thick film ceramics made of commercial TiO2 powder has been studied. The TiO2 powder was nano sized one that was derived from dried TiO2 suspension. The TiO2 suspension was made by pouring some blended commercial TiO2 powder into some amount of water. The paste of TiO2 was made by mixing the nano sized TiO2 powder with organic vehicle and glass frit. The paste was spread on a glass substrate. The paste was dried at 100 °C and heated at different temperatures (400 °C and 500 °C) for 60 minutes to produce thick film ceramics. The photocatalytic activity of these films was evaluated by measuring the concentration of a solution of methylene blue where the thick films were inside after being illuminated by UV light at various periods of times. The initial concentration of the methylene blue solution was 5 ppm. Structural analyses were carried out by X-ray diffraction (XRD). The XRD analyses showed that the produced thick film ceramic had mainly crystal structure of anatase. According to the photocatalytical data, it was known that the produced thick film ceramics were photocatalyst which were capable of decomposing an organic compound such as the methylene blue.

  11. Fabrication of TiO{sub 2} Thick Film for Photocatalyst from Commercial TiO{sub 2} Powder

    SciTech Connect

    Asteti, S. Fuji; Syarif, D. Gustaman

    2008-03-17

    Photocatalytic activity of TiO{sub 2} thick film ceramics made of commercial TiO{sub 2} powder has been studied. The TiO{sub 2} powder was nano sized one that was derived from dried TiO{sub 2} suspension. The TiO{sub 2} suspension was made by pouring some blended commercial TiO{sub 2} powder into some amount of water. The paste of TiO{sub 2} was made by mixing the nano sized TiO{sub 2} powder with organic vehicle and glass frit. The paste was spread on a glass substrate. The paste was dried at 100 deg. C and heated at different temperatures (400 deg. C and 500 deg. C) for 60 minutes to produce thick film ceramics. The photocatalytic activity of these films was evaluated by measuring the concentration of a solution of methylene blue where the thick films were inside after being illuminated by UV light at various periods of times. The initial concentration of the methylene blue solution was 5 ppm. Structural analyses were carried out by X-ray diffraction (XRD). The XRD analyses showed that the produced thick film ceramic had mainly crystal structure of anatase. According to the photocatalytical data, it was known that the produced thick film ceramics were photocatalyst which were capable of decomposing an organic compound such as the methylene blue.

  12. Improvement of Flame-made ZnO Nanoparticulate Thick Film Morphology for Ethanol Sensing

    PubMed Central

    Liewhiran, Chaikarn; Phanichphantandast, Sukon

    2007-01-01

    ZnO nanoparticles were produced by flame spray pyrolysis using zinc naphthenate as a precursor dissolved in toluene/acetonitrile (80/20 vol%). The particles properties were analyzed by XRD, BET. The ZnO particle size and morphology was observed by SEM and HR-TEM revealing spheroidal, hexagonal, and rod-like morphologies. The crystallite sizes of ZnO spheroidal and hexagonal particles ranged from 10-20 nm. ZnO nanorods were ranged from 10-20 nm in width and 20-50 nm in length. Sensing films were produced by mixing the nanoparticles into an organic paste composed of terpineol and ethyl cellulose as a vehicle binder. The paste was doctor-bladed onto Al2O3 substrates interdigitated with Au electrodes. The morphology of the sensing films was analyzed by optical microscopy and SEM analysis. Cracking of the sensing films during annealing process was improved by varying the heating conditions. The gas sensing of ethanol (25-250 ppm) was studied at 400 °C in dry air containing SiC as the fluidized particles. The oxidation of ethanol on the surface of the semiconductor was confirmed by mass spectroscopy (MS). The effect of micro-cracks was quantitatively accounted for as a provider of extra exposed edges. The sensitivity decreased notably with increasing crack of sensing films. It can be observed that crack widths were reduced with decreasing heating rates. Crack-free of thick (5 μm) ZnO films evidently showed higher sensor signal and faster response times (within seconds) than cracked sensor. The sensor signal increased and the response time decreased with increasing ethanol concentration.

  13. Dependence of the optimum parameters of femtosecond laser annealing of lead zirconate titanate films on their thickness

    NASA Astrophysics Data System (ADS)

    Elshin, A. S.; Abdullaev, D. A.; Mishina, E. D.

    2016-06-01

    The optimum parameters of laser annealing (crystallization) induced by repetitive pulses with a pulse duration of 100 fs and a wavelength of 800 nm, which falls in the transparency region of the film and, simultaneously, in the absorption region of the substrate, have been investigated experimentally as a function of the thickness of the ferroelectric film. It has been shown that, with an increase in the thickness of the ferroelectric film by 100 nm (in the range from 300 to 600 nm), the required power density of the laser beam increases, on the average, by 0.1 MW/cm2. The optimum exposure time of the laser beam with the desired power increases nonlinearly with an increase in the thickness of the film.

  14. Comparison of Structural and Optoelectronic Properties of N-Type Microcrystalline Silicon and Silicon Oxide Films with Lowering of Thickness

    NASA Astrophysics Data System (ADS)

    Banerjee, Chandan; Sarker, Arindam; Barua, Asok K.

    2002-08-01

    We have compared the structural and optoelectronic properties of n-type microcrystalline hydrogenated silicon oxide (n-μc-SiO:H) and n-type microcrystalline hydrogenated silicon (n-μc-Si:H) films with lowering of thickness, prepared by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD, 13.56 MHz) method. At thickness ≤ 300 Å, the n-μc-SiO:H film has higher optical gap (E05) and lower optical absorption while retaining the photoconductivity (σph) and activation energy (Ea) similar to those for n-μc-Si:H film. Due to these advantages of n-μc-SiO:H film over that of n-μc-Si:H at low thickness this material has potential for use in improving the performance of single and double junction amorphous silicon solar cells.

  15. Measurement of Oil Film Thickness between Bush and Blade in Swing Type Refrigerant Compressor

    NASA Astrophysics Data System (ADS)

    Tanaka, Shinji; Zuo, Siyang; Hikam, Achmad; Toyama, Toshiyuki

    A swing type refrigerant compressor was developed in order to overcome problems related to lubrication of a rotary compressor. However, the lubrication condition of the swing compressor has not been measured quantitatively yet. This paper describes an application of an eddy current displacement sensor to measure oil film thickness of a sliding part between a suction side bush and a blade in the swing compressor, and examined lubrication condition of the sliding part and a motion of the bush against the blade under some operating conditions. The results indicate that the sliding part between the suction side bush and the blade forms a wedge shape in shaft angle from 0° to 180° and forms a negative wedge shape in shaft angle from 180° to 360°. In addition, the results show that the oil film thickness on an upper edge side of the bush and a slope angle of the bush against the blade decrease with an increase of discharge pressure and increase with an increase of operating frequency of the compressor.

  16. New approach to the excitation of plate waves for piezoelectric thick-film devices.

    PubMed

    De Cicco, Giorgio; Morten, Bruno

    2008-12-01

    A method is presented for exciting the propagation of plate waves in elastic guides. It is implemented in a device whose minimum working structure consists of a non-piezoelectric plane guide and two piezoelectric transducers operating as a generator and detector. The device is entirely in accordance with thick-film technology standard procedures. Both transducers are composed of a PZT ferroelectric layer deposited on a ceramic substrate and a suitable system of three coplanar metal electrodes placed inside the same layer. Beside setting the wavelength of propagation, the electrode system promotes piezoelectric deformations parallel to the substrate simultaneously contracting and extending contiguous active regions in the layer. Pure shear stresses are then induced on the involved guide surface, alternately distributed, with the spatial periodicity of the wave that will propagate in the guide. The propagation of several kinds of guided waves is possible so the selection of the one that meets a specific device design best is allowed. This work describes the design, realization and operation of a prototype structure consisting of an alumina plate guide and two pairs of piezoelectric thick-film transducers realized on it. The results related to the propagation of symmetric and asymmetric Lamb modes are reported. Moreover, the potential of the method is highlighted, emphasizing its effectiveness, easy implementation and application in the development of devices for the sensing and non-destructive testing areas. PMID:18486958

  17. Anomalous thickness variation of the foam films stabilized by weak non-ionic surfactants.

    PubMed

    Qu, Xuan; Wang, Liguang; Karakashev, Stoyan I; Nguyen, Anh V

    2009-09-15

    The constant thickness (H) of metastable free films of various non-ionic surfactant solutions was measured at surfactant concentrations less than the critical micelle concentrations or solubility limits with fixed 5x10(-5) M sodium chloride (NaCl) serving as the background electrolyte. The surfactants include n-pentanol, n-octanol, methyl isobutyl carbinol (MIBC), polypropylene glycol (PPG-400), tetraethylene glycol monooctyl ether (C(8)E(4)), and tetraethylene glycol monodecyl ether (C(10)E(4)). H was interferometrically measured. For each surfactant in this study, the H-versus-surfactant-concentration curve finds a peak at a concentration around 5x10(-6)-1x10(-5) M and a valley at a higher concentration. The measured H values were compared to those predicted from the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, which considers solely the contribution from electrostatic double-layer repulsion with van der Waals attraction being neglected in the present work. In determining the double-layer repulsion, the ionic strength was determined from the electrolytic conductivity measurement of the film-forming solutions and the surface potential was estimated from the zeta-potential measurement of air bubbles. It was found that the DLVO theory failed to explain the thickness variance with surfactant concentration, implying that additional non-DLVO attractive forces might be required to explain the experimental results. Finally, the possible origins of these attractive forces were discussed. PMID:19539299

  18. A 240-channel thick film multi-chip module for readout of silicon drift detectors

    NASA Astrophysics Data System (ADS)

    Lynn, D.; Bellwied, R.; Beuttenmueller, R.; Caines, H.; Chen, W.; DiMassimo, D.; Dyke, H.; Elliott, D.; Grau, M.; Hoffmann, G. W.; Humanic, T.; Jensen, P.; Kleinfelder, S. A.; Kotov, I.; Kraner, H. W.; Kuczewski, P.; Leonhardt, B.; Li, Z.; Liaw, C. J.; LoCurto, G.; Middelkamp, P.; Minor, R.; Mazeh, N.; Nehmeh, S.; O'Conner, P.; Ott, G.; Pandey, S. U.; Pruneau, C.; Pinelli, D.; Radeka, V.; Rescia, S.; Rykov, V.; Schambach, J.; Sedlmeir, J.; Sheen, J.; Soja, B.; Stephani, D.; Sugarbaker, E.; Takahashi, J.; Wilson, K.; STAR-SVT Collaboration

    2000-01-01

    We have developed a thick film multi-chip module for readout of silicon drift (or low capacitance ˜200 fF) detectors. Main elements of the module include a custom 16-channel NPN-BJT preamplifier-shaper (PASA) and a custom 16-channel CMOS Switched Capacitor Array (SCA). The primary design criteria of the module were the minimizations of the power (12 mW/channel), noise (ENC=490 e - rms), size (20.5 mm×63 mm), and radiation length (1.4%). We will discuss various aspects of the PASA design, with emphasis on the preamplifier feedback network. The SCA is a modification of an integrated circuit that has been previously described [1]; its design features specific to its application in the SVT (Silicon Vertex Tracker in the STAR experiment at RHIC) will be discussed. The 240-channel multi-chip module is a circuit with five metal layers fabricated in thick film technology on a beryllia substrate and contains 35 custom and commercial integrated circuits. It has been recently integrated with silicon drift detectors in both a prototype system assembly for the SVT and a silicon drift array for the E896 experiment at the Alternating Gradient Synchrotron at the Brookhaven National Laboratory. We will discuss features of the module's design and fabrication, report the test results, and emphasize its performance both on the bench and under experimental conditions.

  19. Elastic modulus and surface tension of a polyurethane rubber in nanometer thick films

    NASA Astrophysics Data System (ADS)

    Zhai, Meiyu; McKenna, Gregory

    2014-03-01

    Estane is a kind of polyurethane with thermodynamically incompatible hard and soft segments. In this study the macro and micro properties of Estane have been characterized and compared. The viscoelastic properties of this material in bulk scale have been determined using dynamic rheometry. Time-temperature superposition was found to be applicable for this material, and a master curve was successfully constructed from the dynamic shear responses of G'(ω) and G''(ω) . Also a novel nano bubble inflation method was used to obtain the creep compliance of the Estane ultrathin films and the results show stiffening in the rubbery region for the Estane over thicknesses ranging from 110nm to 22nm. The dependence of the rubbery stiffening on film thickness is studied and the relative influences of nano confinement and surface tension effect are analyzed using both a direct stress strain analysis and an energy balance method for the membrane. The contributions of surface tension and nano confinement are considered separately. Office of Naval Research under project No.N00014-11-1-0424.

  20. Device characteristics of amorphous ZnSnLiO thin film transistors with various channel layer thicknesses

    NASA Astrophysics Data System (ADS)

    Wang, Hailong; Li, Bin; Zhang, Wenqi; Wu, Huaihao; Zhou, Dongzhan; Yao, Zhigang; Yi, Lixin; Zhang, Xiqing; Wang, Yongsheng

    2016-08-01

    The preparation and characteristics of ZnSnLiO thin film transistors were studied in this work. The ZnSnLiO films, as the channel layers with thickness varied from 20 to 60 nm, were deposited on SiO2/p-type Si substrates by radio frequency magnetron sputtering. The effect of channel layer thickness on the device characteristics of ZnSnLiO TFTs has been investigated to establish optimal channel layer thickness. The transistor with 40-nm-thick ZnSnLiO film shows the best performance with a field-effect mobility of 47 cm2/V s, a threshold voltage of 4.9 V, and an on/off ratio of 7.2 × 106.