WorldWideScience

Sample records for films growth mechanisms

  1. Growth Mechanism of Strain-Dependent Morphological Change in PEDOT:PSS Films.

    Science.gov (United States)

    Lee, Yoo-Yong; Choi, Gwang Mook; Lim, Seung-Min; Cho, Ju-Young; Choi, In-Suk; Nam, Ki Tae; Joo, Young-Chang

    2016-04-29

    Understanding the mechanism of the strain-dependent conductivity change in polymers in stretched conditions is important. We observed a strain-induced growth of the conductive regions of PSS films, induced by a coalescence of conductive PEDOT-rich cores. This growth due to coalescence leads to a gradual decrease in the electrical resistivity up to 95%, independent of the thickness of the PSS films. The primary mechanism for the evolution of the PEDOT-rich cores proceeds by the cores growing larger as they consuming relatively smaller cores. This process is caused by a strain-induced local rearrangement of PEDOT segments in the vicinity of PSS shells around the cores and also changes the chemical environment in PEDOT, induced by the electron-withdrawing effects around the PEDOT chains. The strain-induced growth mechanism is beneficial to understanding the phenomenon of polymeric chain rearrangement in mechanical deformation and to modulating the electrical conductivity for practical applications.

  2. Growth mechanism and edge effect of buckling patterns in elastic films deposited on stiff substrates

    Science.gov (United States)

    Ye, Quan-Lin; Yu, Sen-Jiang

    2013-12-01

    Elastic tantalum films have been prepared on stiff substrates (glass slides) by direct current magnetron sputtering, and the growth mechanism and edge effect of buckling patterns originated from the release of large compressive stress are investigated. The buckling patterns are found to nucleate at the film edge, and then propagate into the central area and follow an exponential growth behaviour. In the vicinity of the film edge, they generally have first a straight-sided shape perpendicular to the edge, and then transform into bifurcation and buckle network (or telephone-cord structures). Various geometrical parameters including spacing, length and width of the straight-sided buckles near the film edge have been measured and analysed in detail.

  3. The growth mechanism of the colored film on the stainless steel studied by 18O tracing and nuclear reaction analysis

    International Nuclear Information System (INIS)

    Xu Jian; Bai Xinde; He Fei; Fan Yudian

    1999-01-01

    A variety of colored films on stainless steel were achieved when immersed in a solution containing CrO 3 and H 2 SO 4 at 70 deg. C. The thickness of the colored film was determined as the function of time. The depth profiles of Fe and other elements were determined using Auger Electron Spectroscopy (AES). The thickness of the films was measured using AES and Ellipsometry (ELL). The valence of the oxides in the films is analyzed by X-ray Photoemission Spectroscopy (XPS). 18 O tracing techniques were employed to study the microscopic growth mechanism of the film on the stainless steel. Depth profiles of 18 O in the film were determined by using the 2 keV wide resonance at 629 keV of the 18 O(p,α) 15 N reaction. A growth mechanism of the film formed on the stainless steel was proposed

  4. Texture control and growth mechanism of WSe{sub 2} film prepared by rapid selenization of W film

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongchao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Chongyi Zhangyuan Tungsten Industry Corporation Limited, Ganzhou 341300 (China); Gao, Di; Li, Kun; Pang, Mengde; Xie, Senlin [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Liu, Rutie, E-mail: llrrtt@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Zou, Jianpeng [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

    2017-02-01

    Highlights: • We present a highly efficient method for preparing WSe{sub 2} film by rapid selenization. • The W film phase composition has little effect on WSe{sub 2} film orientation. • W film density is a critical factor that influences the WSe{sub 2} orientation. • A growth model was proposed for two kinds of WSe{sub 2} film textures. - Abstract: The tungsten diselenide (WSe{sub 2}) films with different orientation present unique properties suitable for specific applications, such as WSe{sub 2} with a C-axis⊥substrate for optoelectronics and WSe{sub 2} with a C-axis // substrate for electrocatalysts. Orientation control of WSe{sub 2} is essential for realizing the practical applications. In this letter, a WSe{sub 2} film has been prepared via rapid selenization of a magnetron-sputtered tungsten (W) film. The influence of the magnetron-sputtered W film on WSe{sub 2} film growth was studied systematically. Scanning electron microscopy, X-ray diffractometry and high-resolution transmission electron microscopy were used to evaluate the morphology, microstructure and phase composition of the W and WSe{sub 2} films. The substrate temperature has a significant effect on the W film phase composition, but little effect on the WSe{sub 2} film orientation. The WSe{sub 2} orientation can be controlled by changing the W film microstructure. A dense W film that is deposited at low pressure is conducive to the formation of WSe{sub 2} with a C-axis⊥substrate, whereas a porous W film deposited at high pressure favors the formation of WSe{sub 2} with a C-axis // substrate. A growth model for the WSe{sub 2} film with different texture has been proposed based on the experimental results. The direction of selenium (Se) vapor diffusion differs at the top and side surfaces. This is a key factor for the preparation of anisotropic WSe{sub 2} films. Highly oriented WSe{sub 2} films with a C-axis⊥substrate grow from the dense W film deposited at low pressure because Se vapor

  5. A study on the growth mechanism and the process parameters controlling aluminum oxide thin films deposition by pulsed pressure MOCVD

    OpenAIRE

    Murthy, Hari; Miya, S. S; Krumdieck, Susan

    2016-01-01

    Aluminum oxide thin films were deposited on silicon substrates under different deposition conditions using pulse pressure metal organic chemical vapour deposition (PP-MOCVD). The current study investigates into the growth mechanism of the deposited film and the control of the film morphology by varying the processing parameters of PP-MOCVD - choice of solvent, concentration, and presence of a shield. Aluminum sec-butoxide (ASB) was used as the aluminum source while hexane and toluene were use...

  6. Ellipsometry of anodic film growth

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.G.

    1978-08-01

    An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen are patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.

  7. Investigation of a Simplified Mechanism Model for Prediction of Gallium Nitride Thin Film Growth through Numerical Analysis

    Directory of Open Access Journals (Sweden)

    Chih-Kai Hu

    2017-03-01

    Full Text Available A numerical procedure was performed to simplify the complicated mechanism of an epitaxial thin-film growth process. In this study, three numerical mechanism models are presented for verifying the growth rate of the gallium nitride (GaN mechanism. The mechanism models were developed through rate of production analysis. All of the results can be compared in one schematic diagram, and the differences among these three mechanisms are pronounced at high temperatures. The simplified reaction mechanisms were then used as input for a two-dimensional computational fluid dynamics code FLUENT, enabling the accurate prediction of growth rates. Validation studies are presented for two types of laboratory-scale reactors (vertical and horizontal. A computational study including thermal and flow field was also performed to investigate the fluid dynamic in those reactors. For each study, the predictions agree acceptably well with the experimental data, indicating the reasonable accuracy of the reaction mechanisms.

  8. Mechanical integrity of thin films

    International Nuclear Information System (INIS)

    Hoffman, R.W.

    1979-01-01

    Mechanical considerations starting with the initial film deposition including questions of adhesion and grading the interface are reviewed. Growth stresses, limiting thickness, stress relief, control aging, and creep are described

  9. Mechanism of high growth rate for diamond-like carbon films synthesized by helicon wave plasma chemical vapor deposition

    Science.gov (United States)

    Peiyu, JI; Jun, YU; Tianyuan, HUANG; Chenggang, JIN; Yan, YANG; Lanjian, ZHUGE; Xuemei, WU

    2018-02-01

    A high growth rate fabrication of diamond-like carbon (DLC) films at room temperature was achieved by helicon wave plasma chemical vapor deposition (HWP-CVD) using Ar/CH4 gas mixtures. The microstructure and morphology of the films were characterized by Raman spectroscopy and scanning electron microscopy. The diagnosis of plasma excited by a helicon wave was measured by optical emission spectroscopy and a Langmuir probe. The mechanism of high growth rate fabrication for DLC films by HWP-CVD has been discussed. The growth rate of the DLC films reaches a maximum value of 54 μm h‑1 at the CH4 flow rate of 85 sccm, which is attributed to the higher plasma density during the helicon wave plasma discharge. The CH and H α radicals play an important role in the growth of DLC films. The results show that the H α radicals are beneficial to the formation and stabilization of C=C bond from sp2 to sp3.

  10. Analysis of the early growth mechanisms during the chemical deposition of CdS thin films by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval-Paz, M.G., E-mail: myrnasandoval@udec.c [Centro de Investigacion y Estudios Avanzados del IPN. Unidad Queretaro, Apdo. postal 1-798, Queretaro, Qro., 76001 (Mexico); Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Ramirez-Bon, R. [Centro de Investigacion y Estudios Avanzados del IPN. Unidad Queretaro, Apdo. postal 1-798, Queretaro, Qro., 76001 (Mexico)

    2009-10-30

    Chemically deposited CdS thin films were analyzed in this work by means of the spectroscopic ellipsometry technique. The CdS thin films were deposited from an ammonia-free process at short durations in order to obtain information about the layer microstructure and kinetic growth process. We found that the conditions of the ammonia-free reaction solution promote the ion-by-ion deposition process at the early growth stages yielding a compact, high refraction index and highly crystalline oriented CdS layers. Using a concentration of 1.82 mg/ml of cadmium in the reaction solution, the resulting films possess a double layer microstructure which consists of an inner compact layer and an external porous one. The inner layer is developed during the first 15 min of deposition time and it reaches a thickness around of 80 nm. After this time and on this inner layer of CdS, it grows an external porous layer whose thickness increases with the deposition time. The formation of the CdS compact layer at the early stages is related with the ion-by-ion growth mechanism. The subsequent CdS porous layer is formed during the cluster-by-cluster growth stage at longer deposition times. By reducing the cadmium concentration in reaction solution down to 0.76 mg/ml, maintaining constant molar ratio concentrations of Cd/complexing and Cd/thiourea, the chemically deposited CdS films develop only the inner compact layer with a thickness of about 80 nm after 35 min of deposition time.

  11. Growth mechanism of largescale MoS2 monolayer by sulfurization of MoO3 film

    Science.gov (United States)

    Taheri, Payam; Wang, Jieqiong; Xing, Hui; Destino, Joel F.; Murat Arik, Mumtaz; Zhao, Chuan; Kang, Kaifei; Blizzard, Brett; Zhang, Lijie; Zhao, Puqin; Huang, Shaoming; Yang, Sen; Bright, Frank V.; Cerne, John; Zeng, Hao

    2016-07-01

    Monolayer two-dimensional transition metal dichalcogenides (TMDCs) such as MoS2 with broken inversion symmetry possesses two degenerate yet inequivalent valleys that can be selectively excited by circularly polarized light. This unique property renders interesting valley physics. The ability to manipulate valley degrees of freedom with light or external field makes them attractive for optoelectronic and spintronic applications. There is great demand for large area monolayer (ML) TMDCs for certain measurements and device applications. Recent reports on large area ML TDMCs focus on chemical vapor deposition growth. In this work, we report a facile approach to grow largescale continuous ML MoS2 nearly free of overgrowth and voids, by sulfurizing evaporated molybdenum trioxide ultrathin films. Photo conductivity scales with device sizes up to 4.5 mm, suggesting excellent film uniformity. The growth mechanism is found to be vaporization, diffusion, sulfurization and lateral growth, all at local micrometer scale. Our approach provides a new pathway for large-area ML TMDC growth and lithography-free device fabrication.

  12. Ion beam assisted film growth

    CERN Document Server

    Itoh, T

    2012-01-01

    This volume provides up to date information on the experimental, theoretical and technological aspects of film growth assisted by ion beams.Ion beam assisted film growth is one of the most effective techniques in aiding the growth of high-quality thin solid films in a controlled way. Moreover, ion beams play a dominant role in the reduction of the growth temperature of thin films of high melting point materials. In this way, ion beams make a considerable and complex contribution to film growth. The volume will be essential reading for scientists, engineers and students working in thi

  13. Electrodeposition of CdTe thin films onto n-Si(1 0 0): nucleation and growth mechanisms

    International Nuclear Information System (INIS)

    Gomez, H.; Henriquez, R.; Schrebler, R.; Cordova, R.; Ramirez, D.; Riveros, G.; Dalchiele, E.A.

    2005-01-01

    The mechanisms related to the initial stages of the nucleation and growth of cadmium telluride (CdTe) thin films on the rough face side of a (1 0 0) monocrystalline n-type silicon have been studied as a function of different potential steps that varied from an initial value of -0.200 V to values comprised between -0.515 and -0.600 V versus saturated calomel electrode (SCE). The analysis of the corresponding potentiostatic j/t transients suggests that the main phenomena involved at short times is the formation of a Te-Cd bi-layer (BL). For potentials below -0.540 V, the formation of this bi-layer can be considered independent of potential. At greater times, the mechanisms is controlled by two process: (i) progressive nucleation three dimensional charge transfer controlled growth (PN-3D) ct and (ii) progressive nucleation three dimensional diffusion controlled growth (PN-3D) diff , both giving account for the formation of conical and hemispherical nuclei, respectively. Ex situ AFM images of the surface seem to support these assumptions

  14. Comprehensive study of growth mechanism and properties of low Zn content Cd{sub 1-x}Zn{sub x}S thin films by chemical bath

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Carlos Anibal [Multidisciplinary Research Institute in Science and Technology, Ineergias, University of La Serena (Chile); Sandoval-Paz, Myrna Guadalupe; Saavedra, Renato; De la Carrera, Francisco [Department of Physics, Faculty of Physical and Mathematical Sciences, University of Concepcion (Chile); Trejo-Cruz, Cuauhthemoc [Department of Physics, Faculty of Sciences, University of Biobio, Concepcion (Chile); Aragon, Luis E.; Sirena, Martin [Centro Atomico Bariloche & Instituto Balseiro, CNEA & Univ. Nac. de Cuyo, Bariloche, Rio Negro (Argentina); Delplancke, Marie-Paule [4MAT, Universite Libre de Bruxelles, Brussels (Belgium); Carrasco, Claudia [Department of Materials Engineering, Faculty of Engineering, University of Concepcion (Chile)

    2016-11-15

    Cd{sub 1-x}Zn{sub x}S thin films have been studied extensively as window layers for solar cell applications. However, a mismatch between the Cd{sub 1-x}Zn{sub x}S and copper-indium-gallium-selenide absorber layers increases with Zn film concentration, which reduces the device efficiency. In this work, Cd{sub 1-x}Zn{sub x}S thin films with low Zn concentrations were analyzed. The effect of the addition of different molar Zn concentrations to the reaction mixture on the growth mechanism of Cd{sub 1-x}Zn{sub x}S thin films and the influence of these mechanisms on structural, optical and morphological properties of the films has been studied. Cd{sub 1-x}Zn{sub x}S thin films were synthesized by chemical bath deposition using an ammonia-free alkaline solution. Microstructural analysis by X-ray diffraction showed that all deposited films grew with hexagonal structure and crystallite sizes decreased as the Zn concentration in the film increased. Optical measurements indicated a high optical transmission between 75% and 90% for wavelengths above the absorption edge. Band gap value increased from 2.48 eV to 2.62 eV, and the refractive index values for Cd{sub 1-x}Zn{sub x}S thin films decreased as the Zn increased. These changes in films and properties are related to a modification in growth mechanism of the Cd{sub 1-x}Zn{sub x}S thin films, with the influence of Zn(OH){sub 2} formation being more important as Zn in solution increases. (author)

  15. Self-regulating MBE growth of stoichiometric BaSnO3 films via reactive radical mechanism

    Science.gov (United States)

    Prakash, Abhinav; Dewey, John; Yun, Hwanhui; Jeong, Jong Seok; Mkhoyan, K. Andre; Jalan, Bharat

    Growth of thin films comprising of element with low oxidation potential such as Sn often requires reactive oxidants such as ozone or high-pressure oxygen plasma. By utilizing the chemistry of highly reactive radical of Sn, we will present on the growth of phase-pure, epitaxial BaSnO3 films using a hybrid molecular beam epitaxy (MBE) approach with scalable growth rates. The notable finding was that Sn radicals are very reactive to yield phase-pure BaSnO3 films even in molecular oxygen. In this approach, we use hexamethylditin (HMDT) as a tin source, a solid effusion cell for Ba and either molecular oxygen or an rf oxygen plasma source. Phase-pure BaSnO3 films were grown at 900 0C, and oxygen pressure of 5x10-6 Torr as a function Sn:Ba ratio. In-situ time-dependent RHEED intensity oscillations were observed establishing a layer-by-layer growth mode and a critical thickness of ~1 nm for strain relaxation. Rutherford backscattering spectrometry and lattice constant determined using high-resolution X-ray diffraction was used to optimize cation stoichiometry. ``MBE growth window'' was identified where films show bulk-like lattice parameter (4.116 Å) over a wide-range of cation flux ratios. A correlation between RHEED patterns, stoichiometry, and surface morphology was established This work is supported primarily by NSF (DMR-1410888).

  16. Epitaxial growth of manganese oxide films on MgAl2O4 (001) substrates and the possible mechanism

    Science.gov (United States)

    Ren, Lizhu; Wu, Shuxiang; Zhou, Wenqi; Li, Shuwei

    2014-03-01

    Three types of manganese oxide films were grown on MgAl2O4 (001) substrates by plasma-assisted molecular beam epitaxy (PA-MBE) under different growth rates and substrate temperatures. The structural characteristics and chemical compositions of the films were investigated by using in-situ reflection high-energy electron diffraction (RHEED), ex-situ X-ray diffraction, Raman, and X-ray photoelectron spectra (XPS). At a lower substrate temperature (730 K), the epitaxial film tends to form mixed phases with a coexistence of Mn3O4 and Mn5O8 in order to relieve the mismatch-strain. However, at a higher substrate temperature (750 K), all of the films crystallize into Mn3O4; the critical thickness of the film grown under a lower growth rate (7 Å/min) is much larger than that under a high growth rate (10 Å/min). When the film reaches a certain critical thickness, the surface will become fairly rough, and another oriented phase Mn3O4 would crystallize on such a surface.

  17. Kinetics and mechanisms of the oxide film growth on the surface of α-Fe in transitional domains

    International Nuclear Information System (INIS)

    Mukhambetov, D.G.; Berber, N.N.; Kargin, D.B.; Chalaya, O.V.

    2003-01-01

    The object of this work was to study the kinetics of the α-Fe surface oxidation with prevailing cubic texture at temperatures of 450-500 deg. C. The basic conformity to natural laws and mechanisms of the two-phase thin oxide films grows are determined. (author)

  18. Growth mechanism and electronic properties of epitaxial In{sub 2}O{sub 3} films on sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ch. Y.; Kirste, L.; Roehlig, C. C.; Koehler, K.; Cimalla, V.; Ambacher, O. [Fraunhofer-Institute for Applied Solid State Physics, Tullastrasse 72, 79108 Freiburg (Germany); Morales, F. M.; Manuel, J. M.; Garcia, R. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Universidad de Cadiz, Puerto Real, Cadiz 11510 (Spain)

    2011-11-01

    In this work, we report on the epitaxial growth of high-quality cubic indium oxide thick films on c-plane sapphire substrates using a two-step growth process. The epitaxial relationship of In{sub 2}O{sub 3} on (0001) Al{sub 2}O{sub 3} has been investigated. The (222) plane spacing and lattice parameter of a most strain-relaxed high-quality In{sub 2}O{sub 3} film have been determined to be 292.58 pm and 1013.53 pm, respectively. The electronic properties in dependence of the film thickness are interpreted using a three-region model. The density at the surface and interface totals (3.3{+-}1.5)x10{sup 13}cm{sup -2}, while the background electron density in the bulk was determined to be (2.4{+-}0.5)x10{sup 18}cm{sup -3}. Furthermore, post treatments such as irradiation via ultraviolet light and ozone oxidation have been found to influence only the surface layer, while the bulk electronic properties remain unchanged.

  19. Growth mechanisms of GaSb heteroepitaxial films on Si with an AlSb buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Vajargah, S. Hosseini; Botton, G. A. [Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Canadian Centre for Electron Microscopy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Ghanad-Tavakoli, S. [Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Preston, J. S.; Kleiman, R. N. [Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L7 (Canada)

    2013-09-21

    The initial growth stages of GaSb epilayers on Si substrates and the role of the AlSb buffer layer were studied by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Heteroepitaxy of GaSb and AlSb on Si both occur by Volmer-Weber (i.e., island mode) growth. However, the AlSb and GaSb islands have distinctly different characteristics as revealed through an atomic-resolution structural study using Z-contrast of HAADF-STEM imaging. While GaSb islands are sparse and three dimensional, AlSb islands are numerous and flattened. The introduction of 3D island-forming AlSb buffer layer facilitates the nucleation of GaSb islands. The AlSb islands-assisted nucleation of GaSb islands results in the formation of drastically higher quality planar film at a significantly smaller thickness of films. The interface of the AlSb and GaSb epilayers with the Si substrate was further investigated with energy dispersive X-ray spectrometry to elucidate the key role of the AlSb buffer layer in the growth of GaSb epilayers on Si substrates.

  20. Growth mechanisms of GaSb heteroepitaxial films on Si with an AlSb buffer layer

    International Nuclear Information System (INIS)

    Vajargah, S. Hosseini; Botton, G. A.; Ghanad-Tavakoli, S.; Preston, J. S.; Kleiman, R. N.

    2013-01-01

    The initial growth stages of GaSb epilayers on Si substrates and the role of the AlSb buffer layer were studied by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Heteroepitaxy of GaSb and AlSb on Si both occur by Volmer-Weber (i.e., island mode) growth. However, the AlSb and GaSb islands have distinctly different characteristics as revealed through an atomic-resolution structural study using Z-contrast of HAADF-STEM imaging. While GaSb islands are sparse and three dimensional, AlSb islands are numerous and flattened. The introduction of 3D island-forming AlSb buffer layer facilitates the nucleation of GaSb islands. The AlSb islands-assisted nucleation of GaSb islands results in the formation of drastically higher quality planar film at a significantly smaller thickness of films. The interface of the AlSb and GaSb epilayers with the Si substrate was further investigated with energy dispersive X-ray spectrometry to elucidate the key role of the AlSb buffer layer in the growth of GaSb epilayers on Si substrates

  1. Mechanical tension applied to substrate films specifies location of neuritogenesis and promotes major neurite growth at the expense of minor neurite development.

    Science.gov (United States)

    Feng, Zhang-Qi; Franz, Eric W; Leach, Michelle K; Winterroth, Frank; White, Christina M; Rastogi, Arjun; Gu, Zhong-Ze; Corey, Joseph M

    2016-04-01

    One obstacle in neural repair is facilitating axon growth long enough to reach denervated targets. Recent studies show that axonal growth is accelerated by applying tension to bundles of neurites, and additional studies show that mechanical tension is critical to all neurite growth. However, no studies yet describe how individual neurons respond to tensile forces applied to cell bodies and neurites simultaneously; neither do any test motor neurons, a phenotype critical to neural repair. Here we examine the growth of dissociated motor neurons on stretchable substrates. E15 spinal motor neurons were cultured on poly-lactide-co-glycolide films stretched at 4.8, 9.6, or 14.3 mm day(-1). Morphological analysis revealed that substrate stretching has profound effects on developing motor neurons. Stretching increases major neurite length; it also forces neuritogenesis to occur nearest poles of the cell closest to the sources of tension. Stretching also reduces the number of neurites per neuron. These data show that substrate stretching affects neuronal morphology by specifying locations on the cell where neuritogenesis occurs and favoring major neurite growth at the expense of minor neurites. These results serve as a building block for development of new techniques to control and improve the growth of neurons for nerve repair purposes. © 2016 Wiley Periodicals, Inc.

  2. Research and development of photovoltaic power system. Study on growth mechanism of a-Si:H and preparation of the stable, high quality films; Taiyoko hatsuden system no kenkyu kaihatsu. Amorphous silicon no seimaku kiko to kohinshitsuka

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, M. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering

    1994-12-01

    This paper reports the result obtained during fiscal 1994 on research on a film forming mechanism for amorphous silicon for solar cells and its quality improvement. In in-situ observation on plasma CVD surface reaction by using the total reflection infrared absorbing spectroscopy, an observation on a real time basis was performed on the reaction process of an a-Si:H surface in contact with gas mixture plasma composed of SiH4 + CH4. In microscopic observation on initial processes of amorphous silicon growth, surface morphological change before and after a-Si:H deposition at 200{degree}C was observed by using an inter-atomic force microscope. The observation verified that a-Si:H has grown to an atomic layer. In research on defect density in a-Si:H fabricated under high-speed film forming conditions, analysis was made on correlation between the film forming speed at 250{degree}C and defect density in the film. Other research works include those on a high-quality a-SiGe:H film fabricated by using the nanometer film forming/hydrogen plasma annealing method, modulated doping into multi-layer films of a-Si:H/a-Ge:H, and thin film transistor using very thin multi layer films of a-Si:H/a-Ge:H. 5 refs., 12 figs.

  3. Growth of organic films on indoor surfaces

    DEFF Research Database (Denmark)

    Weschler, Charles J.; Nazaroff, W. W.

    2017-01-01

    We present a model for the growth of organic films on impermeable indoor surfaces. The model couples transport through a gas-side boundary layer adjacent to the surface with equilibrium partitioning of semivolatile organic compounds (SVOCs) between the gas phase and the surface film. Model....... Once an SVOC is equilibrated with the film, its mass per unit film volume remains constant, while its mass per unit area increases in proportion to overall film thickness. The predictions of the conceptual model and its mathematical embodiment are generally consistent with results reported in the peer...

  4. Growth of anodic films on niobium

    International Nuclear Information System (INIS)

    Gomes, M.A.B.; Bulhoes, L.O.S.

    1988-01-01

    The analysis of the response of the galvanostatic growth of anodic films on niobium metal in aqueous solutions is shown. The first spark voltage showed a dependence upon value of current density that could be explained as the incorporation of anions into the film. (M.J.C.) [pt

  5. A generalized theory of thin film growth

    Science.gov (United States)

    Du, Feng; Huang, Hanchen

    2018-03-01

    This paper reports a theory of thin film growth that is generalized for arbitrary incidence angle during physical vapor deposition in two dimensions. The accompanying kinetic Monte Carlo simulations serve as verification. A special theory already exists for thin film growth with zero incidence angle, and another theory also exists for nanorod growth with a glancing angle. The theory in this report serves as a bridge to describe the transition from thin film growth to nanorod growth. In particular, this theory gives two critical conditions in analytical form of critical coverage, ΘI and ΘII. The first critical condition defines the onset when crystal growth or step dynamics stops following the wedding cake model for thin film growth. The second critical condition defines the onset when multiple-layer surface steps form to enable nanorod growth. Further, this theory also reveals a critical incidence angle, below which nanorod growth is impossible. The critical coverages, together with the critical incidence angle, defines a phase diagram of thin growth versus nanorod growth.

  6. Role of nucleation in nanodiamond film growth

    International Nuclear Information System (INIS)

    Lifshitz, Y.; Lee, C.H.; Wu, Y.; Zhang, W.J.; Bello, I.; Lee, S.T.

    2006-01-01

    Nanodiamond films were deposited using different microwave plasma chemical vapor deposition schemes following several nucleation pretreatment methods. The nucleation efficiency and the films structure were investigated using scanning and transmission electron microscopy and Raman spectroscopy. C 2 dimer growth (CH 4 and H 2 in 90% Ar) cannot nucleate diamond and works only on existing diamond surfaces. The methyl radical process (up to 20% CH 4 in H 2 ) allows some nucleation probability on appropriate substrates. Prolonged bias enhanced nucleation initiates both diamond nucleation and growth. C 2 dimer growth results in pure nanodiamond free of amorphous carbon, while prolonged bias enhanced nucleation forms an amorphous carbon/nanodiamond composite

  7. Epitaxial nucleation and growth of molecular films

    Science.gov (United States)

    Hooks, Daniel Edwin

    2000-10-01

    The last decade has witnessed an increased emphasis on the design and use of molecular-based materials, commonly in thin film form, as components in electronic devices, sensors, displays, and logic elements. The growing interest in films based on molecular components, rather than their more traditional inorganic counterparts, stems largely from the premise that collective optical and electronic properties can be systematically manipulated through molecular design. Many of these properties depend strongly upon film structure and orientation with respect to the substrate upon which they are deposited. This relationship mandates careful attention to the interface between the primary molecular overlayer and the substrate. Further advances in molecular films and multilayer composites based on molecular films require improved understanding of the role of epitaxy in molecular organization as well as the nucleation events that precede film formation. Determination of critical nucleus dimensions and elucidation of the factors that govern critical size are particularly important for fabricating nanoscale molecular features and controlling domain defects in contiguous molecular films. This thesis describes an examination of the role of epitaxy in the growth of molecular films, including a hierarchical classification and grammar of molecular epitaxy, an atomic force microscopy (AFM) investigation of the intercalation of molecular components into multilayer organic-inorganic composites, and an AFM investigation of the nucleation of molecular films.

  8. Study of diamond film growth and properties

    Science.gov (United States)

    Albin, Sacharial

    1990-01-01

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

  9. Growth of Ge films by cluster beam deposition

    CERN Document Server

    Xu, J L; Feng, J Y

    2002-01-01

    Ge epitaxial layers with reasonable quality were grown on the Si(1 1 1) substrates by cluster beam deposition (CBD) process. The growth temperature plays a dominant role in the epitaxial growth of Ge films. The substrate temperature for epitaxial growth is about 500 deg. C, which is lower than the reported critical temperature of Ge epitaxial growth by MBE and CVD. A stress induced phase transition of Ge lattice from cubic to tetragonal is also observed in the CBD process, and the mechanism is discussed.

  10. Reliability growth of thin film resistors contact

    Directory of Open Access Journals (Sweden)

    Lugin A. N.

    2010-10-01

    Full Text Available Necessity of resistive layer growth under the contact and in the contact zone of resistive element is shown in order to reduce peak values of current flow and power dissipation in the contact of thin film resistor, thereby to increase the resistor stability to parametric and catastrophic failures.

  11. PVA/Polysaccharides Blended Films: Mechanical Properties

    OpenAIRE

    Silva, Fábio E. F.; Di-Medeiros, Maria Carolina B.; Batista, Karla A.; Fernandes, Kátia F.

    2013-01-01

    Blends of polyvinyl alcohol (PVA) and angico gum (AG) and/or cashew gum (CG) were used to produce films by casting method. Morphological and mechanical properties of these films were studied and compared to the properties of a commercial collagen membrane of bovine origin (MBO). The films presented thickness varying from 70 to 140 μm (PVA/AG) and 140 to 200 μm (PVA/CG). Macroscopic analysis showed that a PVA/CG film was very similar to MBO regarding the color and transparency. The higher valu...

  12. PVA/Polysaccharides Blended Films: Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Fábio E. F. Silva

    2013-01-01

    Full Text Available Blends of polyvinyl alcohol (PVA and angico gum (AG and/or cashew gum (CG were used to produce films by casting method. Morphological and mechanical properties of these films were studied and compared to the properties of a commercial collagen membrane of bovine origin (MBO. The films presented thickness varying from 70 to 140 μm (PVA/AG and 140 to 200 μm (PVA/CG. Macroscopic analysis showed that a PVA/CG film was very similar to MBO regarding the color and transparency. The higher values of tensile strength (TS and elastic modulus (EM were observed in the film. On the other hand, PVA/CG and PVA/CG-AG presented the highest value of percentage of elongation (E%. Pearson’s Correlation Analysis revealed a positive correlation between TS and EM and a negative correlation between E% and EM. The PVA/CG film presented mechanical properties very similar to MBO, with the advantage of a higher E% (11.96 than MBO (2.94. The properties of the PVA blended films depended on the polysaccharide added in the blend, as well as the acid used as a catalyst. However, all produced films presented interesting mechanical characteristics which enables several biotechnological applications.

  13. Dynamical mechanism of the liquid film motor

    Science.gov (United States)

    Liu, Zhong-Qiang; Li, Ying-Jun; Zhang, Guang-Cai; Jiang, Su-Rong

    2011-02-01

    The paper presents a simple dynamical model to systemically explain the rotation mechanism of the liquid film motor reported by experiments. The field-induced-plasticity effect of the liquid film is introduced into our model, in which the liquid film in crossed electric fields is considered as a Bingham plastic fluid with equivalent electric dipole moment. Several analytic results involving the torque of rotation, the scaling relation of the threshold fields, and the dynamics equation of a square film and its solution are obtained. We find that the rotation of the liquid film motor originates from the continuous competition between the destruction and the reestablishment of the polarization equilibrium maintained by the external electric field, which is free from the boundary effects. Most experimental phenomena observed in direct current electric fields are interpreted well.

  14. Mechanical characterization of commercial biodegradable plastic films

    Science.gov (United States)

    Vanstrom, Joseph R.

    Polylactic acid (PLA) is a biodegradable plastic that is relatively new compared to other plastics in use throughout industry. The material is produced by the polymerization of lactic acid which is produced by the fermentation of starches derived from renewable feedstocks such as corn. Polylactic acid can be manufactured to fit a wide variety of applications. This study details the mechanical and morphological properties of selected commercially available PLA film products. Testing was conducted at Iowa State University and in conjunction with the United States Department of Agriculture (USDA) BioPreferred ProgramRTM. Results acquired by Iowa State were compared to a similar study performed by the Cortec Corporation in 2006. The PLA films tested at Iowa State were acquired in 2009 and 2010. In addition to these two studies at ISU, the films that were acquired in 2009 were aged for a year in a controlled environment and then re-tested to determine effects of time (ageing) on the mechanical properties. All films displayed anisotropic properties which were confirmed by inspection of the films with polarized light. The mechanical testing of the films followed American Society for Testing and Materials (ASTM) standards. Mechanical characteristics included: tensile strength (ASTM D882), elongation of material at failure (ASTM D882), impact resistance (ASTM D1922), and tear resistance (ASTM D4272). The observed values amongst all the films ranged as followed: tensile strength 33.65--8.54 MPa; elongation at failure 1,665.1%--47.2%; tear resistance 3.61--0.46 N; and puncture resistance 2.22--0.28 J. There were significant differences between the observed data for a number of films and the reported data published by the Cortec Corp. In addition, there were significant differences between the newly acquired material from 2009 and 2010, as well as the newly acquired materials in 2009 and the aged 2009 materials, suggesting that ageing and manufacturing date had an effect on

  15. REVIEW ARTICLE: Nucleation, growth and characterization of cubic boron nitride (cBN) films

    Science.gov (United States)

    Zhang, W. J.; Chong, Y. M.; Bello, I.; Lee, S. T.

    2007-10-01

    Cubic BN (cBN) has a set of extreme properties similar or even superior to diamond. The advance of science and technology of cBN has however been severely hampered by the poor quality of the material available (random orientation, limited film thickness, poor crystallinity and adhesion with substrates due to a non-cubic BN interlayer). This paper reviews the recent progress in the nucleation, growth and characterization techniques of cBN films. It describes various successful approaches in interface engineering and growth techniques in increasing film thickness, improving crystallinity and adhesion of cBN films to the substrate, which are the major issues hindering cBN films for both mechanical and electronic applications. Based on observations of the surface and interface structures, we further discuss the growth mechanisms of cBN films via physical and chemical routes.

  16. Energetic condensation growth of Nb thin films

    Directory of Open Access Journals (Sweden)

    M. Krishnan

    2012-03-01

    Full Text Available This paper describes energetic condensation growth of Nb films using a cathodic arc plasma, whose 60–120 eV ions penetrate a few monolayers into the substrate and enable sufficient surface mobility to ensure that the lowest energy state (crystalline structure with minimal defects is accessible to the film. Heteroepitaxial films of Nb were grown on a-plane sapphire and MgO crystals with good superconducting properties and crystal size (10  mm×20  mm limited only by substrate size. The substrates were heated to temperatures of up to 700°C and coated at 125°C, 300°C, 500°C, and 700°C. Film thickness was varied from ∼0.25  μm to >3  μm. Residual resistivity ratio (⟨RRR⟩ values (up to a record ⟨RRR⟩=587 on MgO and ⟨RRR⟩=328 on a-sapphire depend strongly on substrate annealing and deposition temperatures. X-ray diffraction spectra and pole figures reveal that RRR increases as the crystal structure of the Nb film becomes more ordered, consistent with fewer defects and, hence, longer electron mean-free path. A transition from Nb(110 to Nb(100 orientation on the MgO(100 lattice occurs at higher temperatures. This transition is discussed in light of substrate heating and energetic condensation physics. Electron backscattered diffraction and scanning electron microscope images complement the XRD data.

  17. Surface smoothening effects on growth of diamond films

    Science.gov (United States)

    Reshi, Bilal Ahmad; Kumar, Shyam; Kartha, Moses J.; Varma, Raghava

    2018-04-01

    We have carried out a detailed study of the growth dynamics of the diamond film during initial time on diamond substrates. The diamond films are deposited using Microwave Plasma Chemical Vapor Deposition (MPCVD) method for different times. Surface morphology and its correlation with the number of hours of growth of thin films was invested using atomic force microscopy (AFM). Diamond films have smooth interface with average roughness of 48.6873nm. The initial growth dynamics of the thin film is investigated. Interestingly, it is found that there is a decrease in the surface roughness of the film. Thus a smoothening effect is observed in the grown films. The film enters into the growth regime in the later times. Our results also find application in building diamond detector.

  18. Nanostructured thin films and coatings mechanical properties

    CERN Document Server

    2010-01-01

    The first volume in "The Handbook of Nanostructured Thin Films and Coatings" set, this book concentrates on the mechanical properties, such as hardness, toughness, and adhesion, of thin films and coatings. It discusses processing, properties, and performance and provides a detailed analysis of theories and size effects. The book presents the fundamentals of hard and superhard nanocomposites and heterostructures, assesses fracture toughness and interfacial adhesion strength of thin films and hard nanocomposite coatings, and covers the processing and mechanical properties of hybrid sol-gel-derived nanocomposite coatings. It also uses nanomechanics to optimize coatings for cutting tools and explores various other coatings, such as diamond, metal-containing amorphous carbon nanostructured, and transition metal nitride-based nanolayered multilayer coatings.

  19. Size- and density-controlled deposition of Ag nanoparticle films by a novel low-temperature spray chemical vapour deposition method—research into mechanism, particle growth and optical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yang, E-mail: yang.liu@helmholtz-berlin.de; Plate, Paul, E-mail: paul.plate@helmholtz-berlin.de; Hinrichs, Volker; Köhler, Tristan; Song, Min; Manley, Phillip; Schmid, Martina [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Germany); Bartsch, Peter [Beuth Hochschule für Technik Berlin, Fachbereich VIII Maschinenbau, Veranstaltungstechnik, Verfahrenstechnik (Germany); Fiechter, Sebastian; Lux-Steiner, Martha Ch. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Germany); Fischer, Christian-Herbert [Freie Universität Berlin, Institute of Chemistry and Biochemistry (Germany)

    2017-04-15

    Ag nanoparticles have attracted interest for plasmonic absorption enhancement of solar cells. For this purpose, well-defined particle sizes and densities as well as very low deposition temperatures are required. Thus, we report here a new spray chemical vapour deposition method for producing Ag NP films with independent size and density control at substrate temperatures even below 100 °C, which is much lower than for many other techniques. This method can be used on different substrates to deposit Ag NP films. It is a reproducible, low-cost process which uses trimethylphosphine (hexafluoroacetylacetonato) silver as a precursor in alcoholic solution. By systematic variation of deposition parameters and classic experiments, mechanisms of particle growth and of deposition processes as well as the low decomposition temperature of the precursor could be explained. Using the 3D finite element method, absorption spectra of selected samples were simulated, which fitted well with the measured results. Hence, further applications of such Ag NP films for generating plasmonic near field can be predicted by the simulation.

  20. Spectrum Conversion Film for Regulation of Plant Growth

    OpenAIRE

    Hidaka, Kota; Yoshida, Katsuhira; Shimasaki, Kazuhiro; Murakami, Katsusuke; Yasutake, Daisuke; Kitano, Masaharu

    2008-01-01

    In order to regulate the plant growth, we newly developed the spectrum conversion films (red film and blue film). The red film can convert the blue-green light (450-550 nm) into the red light (600-700 nm), and the blue film can convert the ultraviolet (UV)-violet light (350-450 nm) into the blue-green light. The effect of covering plants with these films on leaf photosynthesis, plant growth and seed germination were examined in three species of plants under the natural light. Leaf photosynthe...

  1. Growth of epitaxial thin films by pulsed laser ablation

    International Nuclear Information System (INIS)

    Lowndes, D.H.

    1992-01-01

    High-quality, high-temperature superconductor (HTSc) films can be grown by the pulsed laser ablation (PLA) process. This article provides a detailed introduction to the advantages and curent limitations of PLA for epitaxial film growth. Emphasis is placed on experimental methods and on exploitation of PLA to control epitaxial growth at either the unit cell or the atomic-layer level. Examples are taken from recent HTSc film growth. 33 figs, 127 refs

  2. Growth and BZO-doping of the nanostructured YBCO thin films on buffered metal substrates

    DEFF Research Database (Denmark)

    Huhtinen, H.; Irjala, M.; Paturi, P.

    2010-01-01

    The growth of the nanostructured YBa2Cu3O6+x (YBCO) films is investigated for the first time on biaxially textured NiW substrates used in coated conductor technology. The optimization process of superconducting layers is made in wide magnetic field and temperature range in order to understand...... the vortex pinning structure and mechanism in our films prepared from nanostructured material. Structural analysis shows that growth mechanism in YBCO films grown on NiW is completely different when compared to YBCO on STO. Films on NiW are much rougher, there is huge in-plane variation of YBCO crystals...... and moreover out-of-plane long range lattice ordering is greatly reduced. Magnetic measurements demonstrate that jc in films grown on NiW is higher in high magnetic fields and low temperatures. This effect is connected to the amount of pinning centres observed in films on metal substrates which are effective...

  3. Correlation between physical properties and growth mechanism of In2S3 thin films fabricated by electrodeposition technique with different deposition times

    Science.gov (United States)

    Braiek, Zied; Gannouni, Mounir; Ben Assaker, Ibtissem; Bardaoui, Afrah; Lamouchi, Amina; Brayek, A.; Chtourou, Radhouane

    2015-10-01

    Indium sulfide (In2S3) thin films were grown on ITO-coated glass substrate using the electrodeposition method. The effect of the deposition time on the structural, morphological, optical and electrical properties of the as-grown In2S3 thin films was studied. XRD spectra of the obtained films reveal the polycrystalline nature of (β-In2S3) with a tetragonal crystal structure along the (109) plane, and exhibit a sharp transition to the (0012) plane when the deposition time is extended beyond 20 min. Using atomic force microscope (AFM), the surface morphology shows a remarkable change in the grain size, thickness, and surface roughness when varying the deposition time. UV-VIS spectrophotometer show that the optical band gap values of In2S3 decrease from about 2.82 to 1.93 eV by extending the electrodeposition duration from 5 to 20 min. All films were found to have an n-type character with a lower electrical resistivity of about 1.8×10-3 Ω cm for films deposited at 20 min.

  4. Review of the fundamentals of thin-film growth.

    Science.gov (United States)

    Kaiser, Norbert

    2002-06-01

    The properties of a thin film of a given material depend on the film's real structure. The real structure is defined as the link between a thin film's deposition parameters and its properties. To facilitate engineering the properties of a thin film by manipulating its real structure, thin-film formation is reviewed as a process starting with nucleation followed by coalescence and subsequent thickness growth, all stages of which can be influenced by deposition parameters. The focus in this review is on dielectric and metallic films and their optical properties. In contrast to optoelectronics all these film growth possibilities for the engineering of novel optical films with extraordinary properties are just beginning to be used.

  5. Growth and structure of thermally evaporated Bi{sub 2}Te{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rogacheva, E.I., E-mail: rogacheva@kpi.kharkov.ua [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine); Budnik, A.V. [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine); Dobrotvorskaya, M.V.; Fedorov, A.G.; Krivonogov, S.I.; Mateychenko, P.V. [Institute for Single Crystals of NAS of Ukraine, 60 Lenin Prospect, Kharkov 61001 (Ukraine); Nashchekina, O.N.; Sipatov, A.Yu. [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine)

    2016-08-01

    The growth mechanism, microstructure, and crystal structure of the polycrystalline n-Bi{sub 2}Te{sub 3} thin films with thicknesses d = 15–350 nm, prepared by thermal evaporation in vacuum onto glass substrates, were studied. Bismuth telluride with Te excess was used as the initial material for the thin film preparation. The thin film characterization was performed using X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scan electron microscopy, and electron force microscopy. It was established that the chemical composition of the prepared films corresponded rather well to the starting material composition and the films did not contain any phases apart from Bi{sub 2}Te{sub 3}. It was shown that the grain size and the film roughness increased with increasing film thickness. The preferential growth direction changed from [00l] to [015] under increasing d. The X-ray photoelectron spectroscopy studies showed that the thickness of the oxidized surface layer did not exceed 1.5–2.0 nm and practically did not change in the process of aging at room temperature, which is in agreement with the results reported earlier for single crystals. The obtained data show that using simple and inexpensive method of thermal evaporation in vacuum and appropriate technological parameters, one can grow n-Bi{sub 2}Te{sub 3} thin films of a sufficiently high quality. - Highlights: • The polycrystalline n-Bi{sub 2}Te{sub 3} thin films were grown thermal evaporation onto glass. • The growth mechanism and film structure were studied by different structure methods. • The grain size and film roughness increased with increasing film thickness. • The growth direction changes from [00l] to [015] under film thickness increasing. • The oxidized layer thickness (1–2 nm) did not change under aging at room temperature.

  6. Particle growth mechanisms in Ag-ZrO2 and Au-ZrO2 granular films obtained by pulsed laser deposition

    International Nuclear Information System (INIS)

    Konstantinovic, Zorica; Muro, Montserrat Garcia del; Varela, Manuel; Batlle, Xavier; Labarta, AmIlcar

    2006-01-01

    Thin films consisting of Ag and Au nanoparticles embedded in amorphous ZrO 2 matrix were grown by pulsed laser deposition in a wide range of metal volume concentrations in the dielectric regime (0.08 Ag Au c (Ag)∼0.28 and x c (Au)∼0.52)

  7. Growth Mechanism of Nanowires: Ternary Chalcogenides

    Science.gov (United States)

    Singh, N. B.; Coriell, S. R.; Hopkins, R. H.; Su, Ching Hua; Arnold, B.; Choa, Fow-Sen; Cullum, Brian

    2016-01-01

    In the past two decades there has been a large rise in the investment and expectations for nanotechnology use. Almost every area of research has projected improvements in sensors, or even a promise for the emergence of some novel device technologies. For these applications major focuses of research are in the areas of nanoparticles and graphene. Although there are some near term applications with nanowires in photodetectors and other low light detectors, there are few papers on the growth mechanism and fabrication of nanowire-based devices. Semiconductor nanowires exhibit very favorable and promising optical properties, including high transparency and a several order of magnitude better photocurrent than thin film and bulk materials. We present here an overview of the mechanism of nanowire growth from the melt, and some preliminary results for the thallium arsenic selenide material system. Thallium arsenic selenide (TAS) is a multifunctional material combining excellent acousto-optical, nonlinear and radiation detection properties. We observed that small units of (TAS) nanocubes arrange and rearrange at moderate melt undercooling to form the building block of a nanowire. In some cases very long wires (less than mm) are formed. Since we avoided the catalyst, we observed self-nucleation and uncontrolled growth of wires from different places.

  8. The mechanical properties of thin alumina film deposited by metal-organic chemical vapour deposition

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; Gellings, P.J.; van de Vendel, D.; Metselaar, H.S.C.; van Corbach, H.D.; Fransen, T.

    1995-01-01

    Amorphous alumina films were deposited by metal-organic chemical vapour deposition (MOCVD) on stainless steel, type AISI 304. The MOCVD experiments were performed in nitrogen at low and atmospheric pressures. The effects of deposition temperature, growth rate and film thickness on the mechanical

  9. Growth Mechanism for Low Temperature PVD Graphene Synthesis on Copper Using Amorphous Carbon

    Science.gov (United States)

    Narula, Udit; Tan, Cher Ming; Lai, Chao Sung

    2017-03-01

    Growth mechanism for synthesizing PVD based Graphene using Amorphous Carbon, catalyzed by Copper is investigated in this work. Different experiments with respect to Amorphous Carbon film thickness, annealing time and temperature are performed for the investigation. Copper film stress and its effect on hydrogen diffusion through the film grain boundaries are found to be the key factors for the growth mechanism, and supported by our Finite Element Modeling. Low temperature growth of Graphene is achieved and the proposed growth mechanism is found to remain valid at low temperatures.

  10. Intrinsic flux pinning mechanisms in different thickness MgB2 films

    Directory of Open Access Journals (Sweden)

    C. Yang

    2017-03-01

    Full Text Available MgB2 films in four thickness (60 nm, 200nm, 600nm and 1μm have been fabricated by hybrid physical–chemical vapor deposition technique (HPCVD. By measuring the magnetization hysteresis loops and the resistivity, we have obtained the transport and magnetic properties of the four films. After that, the pinning mechanisms in them were discussed. Comparing the pinning behaviors in these ultrathin films, thin films and thick films, it was found that there exist different pinning types in MgB2 films of different thickness. In combination with the study of the surface morphology, cross-section and XRD results, we concluded that MgB2 films had different growth modes in different growth stages. For thin films, films grew along c axis, and grain boundaries acted as surface pinning. While for thick films, films grew along c axis at first, and then changed to a-b axis growth. As a result, the a-b axis grains acted as strong volume pinning.

  11. Oxygen-induced giant grain growth in Ag films

    Science.gov (United States)

    Birnbaum, A. J.; Thompson, C. V.; Steuben, J. C.; Iliopoulos, A. P.; Michopoulos, J. G.

    2017-10-01

    Thin film crystallites typically exhibit normal or abnormal growth with maximum grain size limited by energetic and geometric constraints. Although epitaxial methods have been used to produce large single crystal regions, they impose limitations that preclude some compelling applications. The generation of giant grain thin film materials has broad implications for fundamental property analysis and applications. This work details the production of giant grains in Ag films (2.5 μm-thick), ranging in size from ≈50 μm to 1 mm, on silicon nitride films upon silicon substrates. The presence of oxygen during film deposition plays a critical role in controlling grain size and orientation.

  12. Growth of superconducting tantalum films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Scherschel, M. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland) Paul Scherrer Inst., Solid State Div. F3, Villigen (Switzerland)); Finkbeiner, F. (Paul Scherrer Inst., Solid State Div. F3, Villigen (Switzerland)); Zhao, S.P. (Paul Scherrer Inst., Solid State Div. F3, Villigen (Switzerland)); Jaggi, A. (Paul Scherrer Inst., Solid State Div. F3, Villigen (Switzerland)); Maier, T. (Paul Scherrer Inst., Solid State Div. F3, Villigen (Switzerland)); Lerch, P. (Paul Scherrer Inst., Solid State Div. F3, Villigen (Switzerland)); Zehnder, A. (Paul Scherrer Inst., Solid State Div. F3, Villigen (Switzerland)); Ott, H.R. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland) Paul Scherrer Inst., Solid State Div. F3, Villigen (Switzerland))

    1994-02-01

    Pulsed laser deposition (PLD) was used to grow superconducting Ta-films with critical temperatures close to bulk values (4.5 K) on sapphire substrates. Results are compared with films grown by e-beam evaporation. The PLD method allows the growth of superconducting Ta-films on substrates kept at ambient temperature but film surfaces are plagued by sub-micron particles. On the other hand, e-beam evaporation results in smooth surfaces but requires a substrate temperature of the order of 400 C for producing high-quality superconducting films. Critical temperatures, residual resistance ratios, and crystal structure are presented. (orig.)

  13. Preparation and properties of nanometer silk fibroin peptide/polyvinyl alcohol blend films for cell growth.

    Science.gov (United States)

    Luo, Qin; Chen, Zhongmin; Hao, Xuefei; Zhu, Qiangsong; Zhou, Yucheng

    2013-10-01

    Nanometer silk fibroin peptide (Nano-SFP) was prepared from silkworm cocoons through the process of dissolution, dialysis and enzymolysis. For comparison, silk fibroin was decomposed with α-chymotrypsin, trypsin and neutrase, respectively. From the SEM and particle size analysis results, the Nano-SFP prepared by neutrase was found to be the most desirable at about 50-200 nm. Nano-SFP/polyvinyl alcohol films (Nano-SFP/PVA) were prepared by blending Nano-SFP and PVA in water with different weight ratios of 10/90, 20/80, 30/70, and 40/60. The films were characterized by IR, SEM, TG, DSC and tensile strength test for investigating their structure, surface morphology, thermostability, and mechanical property. The results showed that Nano-SFP inserted in the PVA films with small linear particles, and Nano-SFP/PVA films exhibited smooth surface, good thermostability and tensile strength. The growth of Chinese hamster ovary (CHO) cells on films with and without Nano-SFP was investigated with MTT colorimetric assay to assess the films' ability to promote cell growth. It was observed that the Nano-SFP improved cell adhesion on the film surface, and the ability of promoting cell growth increased with the increasing content of Nano-SFP in the blend films. Nano-SFP/PVA film with the ratio of 30/70 was concluded to have the best properties. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Growth Aspects of Thin-Film Composite Heterostructures of Oxide Multicomponent Perovskites for Electronics

    Science.gov (United States)

    Endo, Kazuhiro; Badica, Petre; Arisawa, Shunichi; Kezuka, Hiroshi; Endo, Tamio

    2012-11-01

    We review, based on our results, the problems and solutions for the growth of thin films and composite heterostructures emphasizing the general growth aspects and principles vs specifics for each material or heterostructure. The materials used in our examples are Bi2Sr2Ca2Cu3O10, Bi2Sr2CaCu2O8, YBa2Cu3O7, (Sr, Ca)CuO2, (Ba, Ca)CuO2, and Bi4Ti3O12. The growth method was metal organic chemical vapor deposition (MOCVD). The presented thin films or heterostructures have c- and non-c-axis orientations. We discuss the implications of the film-substrate lattice relationships, paying attention to film-substrate lattice mismatch anisotropy and to film-film lattice mismatch, which has a significant influence on the quality of the non-c-axis heterostructures. We also present growth control through the use of vicinal substrates and two-temperature (template) and interrupted growth routes allowing significant quality improvements or optimization. Other key aspects of the growth mechanism, that is, roughness, morphology, and interdiffusion, are addressed. It is concluded that the requirements for the growth of non-c-axis heterostructures are more severe than those for the c-axis ones.

  15. Grain coarsening mechanism of Cu thin films by rapid annealing

    International Nuclear Information System (INIS)

    Sasajima, Yasushi; Kageyama, Junpei; Khoo, Khyoupin; Onuki, Jin

    2010-01-01

    Cu thin films have been produced by an electroplating method using nominal 9N anode and nominal 6N CuSO 4 .5H 2 O electrolyte. Film samples were heat-treated by two procedures: conventional isothermal annealing in hydrogen atmosphere (abbreviated as H 2 annealing) and rapid thermal annealing with an infrared lamp (abbreviated as RTA). After heat treatment, the average grain diameters and the grain orientation distributions were examined by electron backscattering pattern analysis. The RTA samples (400 o C for 5 min) have a larger average grain diameter, more uniform grain distribution and higher ratio of (111) orientation than H 2 annealed samples (400 o C for 30 min). This means that RTA can produce films with coarser and more uniformly distributed grains than H 2 annealing within a short time, i.e. only a few minutes. To clarify the grain coarsening mechanism, grain growth by RTA was simulated using the phase field method. The simulated grain diameter reaches its maximum at a heating rate which is the same order as that in the actual RTA experiment. The maximum grain diameter is larger than that obtained by H 2 annealing with the same annealing time at the isothermal stage as in RTA. The distribution of the misorientation was analyzed which led to a proposed grain growth model for the RTA method.

  16. Growth and characterization of ultrathin epitaxial MnO film on Ag(001)

    Science.gov (United States)

    Kundu, Asish K.; Menon, Krishnakumar S. R.

    2016-07-01

    We present here a comprehensive growth procedure to obtain a well-ordered MnO(001) ultrathin film on Ag(001) substrate. Depending upon the oxygen partial pressure during the growth, different phases of manganese oxide have been detected by Low Energy Electron Diffraction (LEED) and X-ray Photoelectron Spectroscopic (XPS) studies. A modified growth scheme has been adopted to get well-ordered and stoichiometric MnO(001) ultrathin film. The detailed growth mechanism of epitaxial MnO film on Ag(001) has been studied step by step, using LEED and XPS techniques. Observation of sharp (1 × 1) LEED pattern with a low inelastic background, corresponds to a long-range atomic order with low defect densities indicating the high structural quality of the film. The Mn 2p and Mn 3s core-level spectra confirm the oxidation state as well as the stoichiometry of the grown MnO films. Apart from the growth optimization, the evolution of strain relaxation of the MnO(001) film with film thickness has been explored.

  17. Mechanical properties of polyelectrolyte multilayer self-assembled films

    International Nuclear Information System (INIS)

    Dai Xinhua; Zhang Yongjun; Guan Ying; Yang Shuguang; Xu Jian

    2005-01-01

    The mechanical properties of electrostatic self-assembled multilayer films from polyacrylic acid (PAA) and C 60 -ethylenediamine adduct (C 60 -EDA) or poly(allylamine hydrochloride) (PAH) were evaluated by atomic force microscopy (AFM) wear experiments. Because of the higher molecular weight of PAH, the wear resistance of the (PAH/PAA) 10 film is higher than that of the (PAH/PAA) 2 (C 60 -EDA/PAA) 8 film; that is, the former is mechanically more stable than the latter. The mechanical stability of both films can be improved significantly by heat treatment, which changes the nature of the linkage from ionic to covalent. The AFM measurement also reveals that the (PAH/PAA) 2 (C 60 -EDA/PAA) 8 film is softer than the (PAH/PAA) 10 film. The friction properties of the heated films were measured. These films can be developed as potential lubrication coatings for microelectromechanical systems

  18. Structural evolution and growth mechanisms of RF-magnetron sputter-deposited hydroxyapatite thin films on the basis of unified principles

    Science.gov (United States)

    Ivanova, Anna A.; Surmeneva, Maria A.; Surmenev, Roman A.; Depla, Diederik

    2017-12-01

    The structural features of RF-magnetron sputter-deposited hydroxyapatite (HA) coatings are investigated in order to reveal the effect of the working gas composition and the sample position of the substrate relative to the target erosion zone. The film properties were observed to change as a result of bombardment with energetic ions. XRD analysis of the coated substrates indicates that with the increase of the ion-to-atom ratio, the fiber texture changes from a mixed (11 2 bar 2) + (0002) over (0002) orientation, finally reaching a (30 3 bar 0) out-of-plane orientation at high ion-to-atom ratios. TEM reveals that the microstructure of the HA coating consists of columnar grains and differs with the coating texture. The contribution of Ji/Ja to the development of microstructure and texture of the HA coating is schematically represented and discussed. The obtained results may contribute substantially to the progress of research into the development of HA coatings with tailored properties, and these coatings may be applied on the surfaces of metal implants used in bone surgery.

  19. Oriented growth of thin films of samarium oxide by MOCVD

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Thin films of Sm2O3 have been grown on Si(100) and fused quartz by low-pressure chemical va- pour deposition using an adducted β-diketonate precursor. The films on quartz are cubic, with no preferred orientation at lower growth temperatures (~ 550°C), while they grow with a strong (111) orientation as the.

  20. PZT thin films for piezoelectric MEMS mechanical energy harvesting

    Science.gov (United States)

    Yeager, Charles

    This thesis describes the optimization of piezoelectric Pb(ZrxTi 1-x)O3 (PZT) thin films for energy generation by mechanical energy harvesting, and self-powered micro-electro-mechanical systems (MEMS). For this purpose, optimization of the material was studied, as was the incorporation of piezoelectric films into low frequency mechanical harvesters. A systematic analysis of the energy harvesting figure of merit was made. As a figure of merit (e31,ƒ)2/epsilon r (transverse piezoelectric coefficient squared over relative permittivity) was utilized. PZT films of several tetragonal compositions were grown on CaF2, MgO, SrTiO3, and Si substrates, thereby separating the dependence of composition on domain orientation. To minimize artifacts associated with composition gradients, and to extend the temperature growth window, PZT films were grown by metal organic chemical vapor deposition (MOCVD). Using this method, epitaxial {001} films achieved c-domain textures above 90% on single crystal MgO and CaF2 substrates. This could be tailored via the thermal stresses established by the differences in thermal expansion coefficients of the film and the substrate. The single-domain e31,ƒ for PZT thin films was determined to exceed -12 C/m2 in the tetragonal phase field for x ≥ 0.19, nearly twice the phenomenologically modeled value. The utilization of c-domain PZT films is motivated by a figure of merit above 0.8 C2/m4 for (001) PZT thin films. Increases to the FoM via doping and hot poling were also quantified; a 1% Mn doping reduced epsilonr by 20% without decreasing the piezoelectric coefficient. Hot poling a device for one hour above 120°C also resulted in a 20% reduction in epsilonr ; furthermore, 1% Mn doping reduced epsilonr by another 12% upon hot poling. Two methods for fabricating thin film mechanical energy harvesting devices were investigated. It was found that phosphoric acid solutions could be used to pattern MgO crystals, but this was typically accompanied by

  1. Uniaxial crystal growth in thin film by utilizing supercooled state of mesogenic phthalocyanine

    Science.gov (United States)

    Fiderana Ramananarivo, Mihary; Higashi, Takuya; Ohmori, Masashi; Sudoh, Koichi; Fujii, Akihiko; Ozaki, Masanori

    2016-06-01

    A method of uniaxial crystal growth in wet-processed thin films of the mesogenic phthalocyanine 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) is proposed. It consists of applying geometrically linear thermal stimulation to a supercooled state of liquid crystalline C6PcH2. The thin film showed highly ordered molecular stacking structure and uniaxial alignment over a macroscopic scale. An explanation of the crystal growth mechanism is suggested by taking into account the temperature range of crystal growth and the hysteresis property of C6PcH2 in the phase transition.

  2. Fundamental Mechanisms of Roughening and Smoothing During Thin Film Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Headrick, Randall [Univ. of Vermont, Burlington, VT (United States)

    2016-03-18

    In this research program, we have explored the fundamental limits for thin film deposition in both crystalline and amorphous (i.e. non-crystalline) materials systems. For vacuum-based physical deposition processes such as sputter deposition, the background gas pressure of the inert gas (usually argon) used as the process gas has been found to be a key variable. Both a roughness transition and stress transition as a function of pressure have been linked to a common mechanism involving collisions of energetic particles from the deposition source with the process inert gas. As energetic particles collide with gas molecules in the deposition process they lose their energy rapidly if the pressure (and background gas density) is above a critical value. Both roughness and stress limit important properties of thin films for applications. In the area of epitaxial growth we have also discovered a related effect; there is a critical pressure below which highly crystalline layers grow in a layer-by-layer mode. This effect is also though to be due to energetic particle thermalization and scattering. Several other important effects such as the observation of coalescence dominated growth has been observed. This mode can be likened to the behavior of two-dimensional water droplets on the hood of a car during a rain storm; as the droplets grow and touch each other they tend to coalesce rapidly into new larger circular puddles, and this process proceeds exponentially as larger puddles overtake smaller ones and also merge with other large puddles. This discovery will enable more accurate simulations and modeling of epitaxial growth processes. We have also observed that epitaxial films undergo a roughening transition as a function of thickness, which is attributed to strain induced by the crystalline lattice mismatch with the substrate crystal. In addition, we have studied another physical deposition process called pulsed laser deposition. It differs from sputter deposition due to the

  3. Chemical structural analysis of diamondlike carbon films: I. Surface growth model

    Science.gov (United States)

    Takabayashi, Susumu; Ješko, Radek; Shinohara, Masanori; Hayashi, Hiroyuki; Sugimoto, Rintaro; Ogawa, Shuichi; Takakuwa, Yuji

    2018-02-01

    The surface growth mechanisms of diamondlike carbon (DLC) films has been clarified. DLC films were synthesized in atmospheres with a fixed methane-to-argon ratio at different temperatures up to 700 °C by the photoemission-assisted glow discharge of photoemission-assisted plasma-enhanced chemical vapor deposition. The electrical resistivity of the films decreased logarithmically as the synthesis temperature was increased. Conversely, the dielectric constant of the films increased and became divergent at high temperature. However, the very high electrical resistivity of the film synthesized at 150 °C was retained even after post-annealing treatments at temperatures up to 500 °C, and divergence of the dielectric constant was not observed. Such films exhibited excellent thermal stability and retained large amounts of hydrogen, even after post-annealing treatments. These results suggest that numerous hydrogen atoms were incorporated into the DLC films during synthesis at low temperatures. Hydrogen atoms terminate carbon dangling bonds in the films to restrict π-conjugated growth. During synthesis at high temperature, hydrogen was desorbed from the interior of the growing films and π-conjugated conductive films were formed. Moreover, hydrogen radicals were chemisorbed by carbon atoms at the growing DLC surface, leading to removal of carbon atoms from the surface as methane gas. The methane molecules decomposed into hydrocarbons and hydrogen radicals through the attack of electrons above the surface. Hydrogen radicals contributed to the etching reaction cycle of the film; the hydrocarbon radicals were polymerized by reacting with other radicals and the methane source. The polymer radicals remained above the film, preventing the supply of the methane source and disrupting the action of argon ions. At high temperatures, the resultant DLC films were rough and thin.

  4. Low-temperature growth of nanostructured diamond films.

    Science.gov (United States)

    Baker, P A; Catledge, S A; Vohra, Y K

    2001-03-01

    Nanostructured diamond films are grown on a titanium alloy substrate using a two-step deposition process. The first step is performed at elevated temperature (820 degrees C) for 30 min using a H2/CH4/N2 gas mixture to grow a thin (approximately 600 nm) nanostructured diamond layer and to improve film adhesion. The remainder of the deposition involves growth at low temperature (diamond film growth during low-temperature deposition is confirmed by in situ laser reflectance interferometry, atomic force microscopy, micro-Raman spectroscopy, and surface profilometry. Similar experiments performed without the initial nanostructured diamond layer resulted in poorly adhered films with a more crystalline appearance and a higher surface roughness. This low-temperature deposition of nanostructured diamond films on metals offers advantages in cases where high residual thermal stress leads to delamination at high temperatures.

  5. On the mechanics of thin films and growing surfaces

    KAUST Repository

    Holland, M. A.

    2013-05-24

    Many living structures are coated by thin films, which have distinct mechanical properties from the bulk. In particular, these thin layers may grow faster or slower than the inner core. Differential growth creates a balanced interplay between tension and compression and plays a critical role in enhancing structural rigidity. Typical examples with a compressive outer surface and a tensile inner core are the petioles of celery, caladium, or rhubarb. While plant physiologists have studied the impact of tissue tension on plant rigidity for more than a century, the fundamental theory of growing surfaces remains poorly understood. Here, we establish a theoretical and computational framework for continua with growing surfaces and demonstrate its application to classical phenomena in plant growth. To allow the surface to grow independently of the bulk, we equip it with its own potential energy and its own surface stress. We derive the governing equations for growing surfaces of zero thickness and obtain their spatial discretization using the finite-element method. To illustrate the features of our new surface growth model we simulate the effects of growth-induced longitudinal tissue tension in a stalk of rhubarb. Our results demonstrate that different growth rates create a mechanical environment of axial tissue tension and residual stress, which can be released by peeling off the outer layer. Our novel framework for continua with growing surfaces has immediate biomedical applications beyond these classical model problems in botany: it can be easily extended to model and predict surface growth in asthma, gastritis, obstructive sleep apnoea, brain development, and tumor invasion. Beyond biology and medicine, surface growth models are valuable tools for material scientists when designing functionalized surfaces with distinct user-defined properties. © The Author(s) 2013.

  6. Decoding Nucleation and Growth of Zeolitic Imidazolate Framework Thin Films with Atomic Force Microscopy and Vibrational Spectroscopy.

    Science.gov (United States)

    Öztürk, Zafer; Filez, Matthias; Weckhuysen, Bert M

    2017-08-10

    The synthesis of metal-organic framework (MOF) thin films has garnered significant attention during the past decade. By better understanding the parameters governing the nucleation and growth of such thin films, their properties can be rationally tuned, empowering their application as (reactive) membranes. Here, a combined AFM-vibrational spectroscopy research strategy is employed to detail the chemistries governing the nucleation and growth of zeolitic imidazolate framework (ZIF) thin films, in particular isostructural Co-ZIF-67 and Zn-ZIF-8. First, a single step direct synthesis approach is used to investigate the influence of different synthesis parameters -metal/linker ratio, temperature, and metal type- on the thin film nucleation and growth behaviour. While the metal/linker ratio has a pronounced effect on the thin film nucleation rate, the temperature mainly influences the growth kinetics of nuclei forming the thin film. In addition, the nucleation and growth of ZIF thin films is shown to be highly dependent on the electronegativity of the metal type. Thin-film thickness control can be achieved by using a multistep synthesis strategy, implying repetitive applications of single step deposition under identical synthesis conditions, for which a growth mechanism is proposed. This study provides insight into the influence of synthesis parameters on the ZIF thin film properties, using tools at hand to rationally tune MOF thin film properties. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  7. Cadmium sulfide thin films growth by chemical bath deposition

    Science.gov (United States)

    Hariech, S.; Aida, M. S.; Bougdira, J.; Belmahi, M.; Medjahdi, G.; Genève, D.; Attaf, N.; Rinnert, H.

    2018-03-01

    Cadmium sulfide (CdS) thin films have been prepared by a simple technique such as chemical bath deposition (CBD). A set of samples CdS were deposited on glass substrates by varying the bath temperature from 55 to 75 °C at fixed deposition time (25 min) in order to investigate the effect of deposition temperature on CdS films physical properties. The determination of growth activation energy suggests that at low temperature CdS film growth is governed by the release of Cd2+ ions in the solution. The structural characterization indicated that the CdS films structure is cubic or hexagonal with preferential orientation along the direction (111) or (002), respectively. The optical characterization indicated that the films have a fairly high transparency, which varies between 55% and 80% in the visible range of the optical spectrum, the refractive index varies from 1.85 to 2.5 and the optical gap value of which can reach 2.2 eV. It can be suggested that these properties make these films perfectly suitable for their use as window film in thin films based solar cells.

  8. Biodegradability and mechanical properties of starch films from Andean crops.

    Science.gov (United States)

    Torres, F G; Troncoso, O P; Torres, C; Díaz, D A; Amaya, E

    2011-05-01

    Different Andean crops were used to obtain starches not previously reported in literature as raw material for the production of biodegradable polymers. The twelve starches obtained were used to prepare biodegradable films by casting. Water and glycerol were used as plasticizers. The mechanical properties of the starch based films were assessed by means of tensile tests. Compost tests and FTIR tests were carried out to assess biodegradability of films. The results show that the mechanical properties (UTS, Young's modulus and elongation at break) of starch based films strongly depend on the starch source used for their production. We found that all the starch films prepared biodegrade following a three stage process and that the weight loss rate of all the starch based films tested was higher than the weight loss rate of the cellulose film used as control. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Growth model of Au films on Ru(001)

    International Nuclear Information System (INIS)

    Canessa, E.; Calmetta, A.

    1992-06-01

    In an attempt to find generic features on the fractal growth of Au films deposited on Ru(001), a simple simulation model based on irreversible diffusion-limited aggregation (DLA) is discussed. Highly irregular two-dimensional dentritic islands of Au particles that gradually grow on a larger host lattice of Ru particles and have fractal dimension d f approx. 1.70 each, are generated via a multiple had-hoc version of the DLA algorithm for single aggregates. Annealing effects on the islands morphology are reproduced assuming different sticking probabilities at nearest-neighbour lattice sites of Au films on Ru(001). Using simulation data, islands growth are described in analogy to diffusion-limited, precipitate growth with soft impingement of precipities. This leads to analyse thin film island growth kinetics in such fractal systems and to predict a main peak in scattering intensity patterns due to interisland interference. (author). 12 refs, 4 figs

  10. Nitrided FeB amorphous thin films for magneto mechanical systems

    International Nuclear Information System (INIS)

    Fernandez-Martinez, I.; Martin-Gonzalez, M.S.; Gonzalez-Arrabal, R.; Alvarez-Sanchez, R.; Briones, F.; Costa-Kraemer, J.L.

    2008-01-01

    The structural, magnetic and magnetoelastic properties of Fe-B-N amorphous films, sputtered from a Fe 80 B 20 target, in a mixture of argon and nitrogen gas, are studied for different nitrogen partial pressures. Nitrogen incorporates into the film preserving the amorphous structure, and modifying magnetic properties. The amount of nitrogen that incorporates into the amorphous structure is found to scale linearly with the nitrogen partial pressure during film growth. The structure, magnetization, field evolution, magnetic anisotropy and magnetostrictive behaviour are determined for films with different nitrogen content. An ∼20% increase of both the saturation magnetization and the magnetostriction constant values is found for moderate (∼8%) nitrogen content when compared to those for pure Fe 80 B 20 amorphous films. These improved properties, together with the still low coercivity of the amorphous films offer great potential for their use in magnetostrictive micro and nano magneto mechanical actuator devices

  11. Nitrided FeB amorphous thin films for magneto mechanical systems

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Martinez, I.; Martin-Gonzalez, M.S. [Instituto de Microelectronica de Madrid, IMM-CNM-CSIC, Isaac Newton 8 PTM, 28760 Tres Cantos, Madrid (Spain); Gonzalez-Arrabal, R. [Instituto de Microelectronica de Madrid, IMM-CNM-CSIC, Isaac Newton 8 PTM, 28760 Tres Cantos, Madrid (Spain); Centro de Microanalisis de Materiales de Materiales, Universidad Autonoma de Madrid, Cantoblanco 28049, Madrid (Spain); Alvarez-Sanchez, R.; Briones, F. [Instituto de Microelectronica de Madrid, IMM-CNM-CSIC, Isaac Newton 8 PTM, 28760 Tres Cantos, Madrid (Spain); Costa-Kraemer, J.L. [Instituto de Microelectronica de Madrid, IMM-CNM-CSIC, Isaac Newton 8 PTM, 28760 Tres Cantos, Madrid (Spain)], E-mail: kramer@imm.cnm.csic.es

    2008-01-15

    The structural, magnetic and magnetoelastic properties of Fe-B-N amorphous films, sputtered from a Fe{sub 80}B{sub 20} target, in a mixture of argon and nitrogen gas, are studied for different nitrogen partial pressures. Nitrogen incorporates into the film preserving the amorphous structure, and modifying magnetic properties. The amount of nitrogen that incorporates into the amorphous structure is found to scale linearly with the nitrogen partial pressure during film growth. The structure, magnetization, field evolution, magnetic anisotropy and magnetostrictive behaviour are determined for films with different nitrogen content. An {approx}20% increase of both the saturation magnetization and the magnetostriction constant values is found for moderate ({approx}8%) nitrogen content when compared to those for pure Fe{sub 80}B{sub 20} amorphous films. These improved properties, together with the still low coercivity of the amorphous films offer great potential for their use in magnetostrictive micro and nano magneto mechanical actuator devices.

  12. Mechanical Properties of ZTO, ITO, and a-Si:H Multilayer Films for Flexible Thin Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Claudia Hengst

    2017-03-01

    Full Text Available The behavior of bi- and trilayer coating systems for flexible a-Si:H based solar cells consisting of a barrier, an electrode, and an absorption layer is studied under mechanical load. First, the film morphology, stress, Young’s modulus, and crack onset strain (COS were analyzed for single film coatings of various thickness on polyethylene terephthalate (PET substrates. In order to demonstrate the role of the microstructure of a single film on the mechanical behavior of the whole multilayer coating, two sets of InSnOx (indium tin oxide, ITO conductive coatings were prepared. Whereas a characteristic grain–subgrain structure was observed in ITO-1 films, grain growth was suppressed in ITO-2 films. ITO-1 bilayer coatings showed two-step failure under tensile load with cracks propagating along the ITO-1/a-Si:H-interface, whereas channeling cracks in comparable bi- and trilayers based on amorphous ITO-2 run through all constituent layers. A two-step failure is preferable from an application point of view, as it may lead to only a degradation of the performance instead of the ultimate failure of the device. Hence, the results demonstrate the importance of a fine-tuning of film microstructure not only for excellent electrical properties, but also for a high mechanical performance of flexible devices (e.g., a-Si:H based solar cells during fabrication in a roll-to-roll process or under service.

  13. Topological Insulator Film Growth by Molecular Beam Epitaxy: A Review

    Directory of Open Access Journals (Sweden)

    Theresa P. Ginley

    2016-11-01

    Full Text Available In this article, we will review recent progress in the growth of topological insulator (TI thin films by molecular beam epitaxy (MBE. The materials we focus on are the V2-VI3 family of TIs. These materials are ideally bulk insulating with surface states housing Dirac excitations which are spin-momentum locked. These surface states are interesting for fundamental physics studies (such as the search for Majorana fermions as well as applications in spintronics and other fields. However, the majority of TI films and bulk crystals exhibit significant bulk conductivity, which obscures these states. In addition, many TI films have a high defect density. This review will discuss progress in reducing the bulk conductivity while increasing the crystal quality. We will describe in detail how growth parameters, substrate choice, and growth technique influence the resulting TI film properties for binary and ternary TIs. We then give an overview of progress in the growth of TI heterostructures. We close by discussing the bright future for TI film growth by MBE.

  14. Growth, structure, morphology, and magnetic properties of Ni ferrite films.

    Science.gov (United States)

    Dong, Chunhui; Wang, Gaoxue; Guo, Dangwei; Jiang, Changjun; Xue, Desheng

    2013-04-27

    The morphology, structure, and magnetic properties of nickel ferrite (NiFe2O4) films fabricated by radio frequency magnetron sputtering on Si(111) substrate have been investigated as functions of film thickness. Prepared films that have not undergone post-annealing show the better spinel crystal structure with increasing growth time. Meanwhile, the size of grain also increases, which induces the change of magnetic properties: saturation magnetization increased and coercivity increased at first and then decreased. Note that the sample of 10-nm thickness is the superparamagnetic property. Transmission electron microscopy displays that the film grew with a disorder structure at initial growth, then forms spinel crystal structure as its thickness increases, which is relative to lattice matching between substrate Si and NiFe2O4.

  15. Computer graphic investigation on the epitaxial growth of superconductor films

    International Nuclear Information System (INIS)

    Miyamoto, A.; Iwamoto, S.; Inui, T.; Agusa, K.

    1989-01-01

    A mechanism of the epitaxial growth the oxide superconductor films has been investigated by using the computer graphics for the combination of orthorhombic Ba 2 YCu 3 O 7-x with substrate crystals such as SrTiO 3 MgO, and ZrO 2 . The (001) plane Ba 2 YCu 3 O 7-x with substrate crystals such as SrTiO 3 , MgO, and ZrO 2 . The (001) plane of Ba 2 YCu 3 O 7-x has been shown to fit the (100) plane of SrTiO 3 , MgO, and ZrO 2 . A crystallographic fit has also been proved between the (110) plane of Ba 2 YCu 3 O 7-x and the (110) plane of SrTiO 3 . These results are consistent with the experimental data about the epitaxial growth of the Ba 2 YCu 3 O 7-x films. Furthermore, detailed investigation of atomic arrangements has indicated some differences in the ionic interaction at the superconductor-substrate interface among SrTiO 3 , MgO, and ZrO 2 substrates. As for ZrO 2 (100) plane, for examples, ionic arrangements at the oxide layer is favorable only for the interaction with Y 3+ layer of Ba 2 YCu 3 O 7-x , while the Zr-O layer of ZrO 2 can interact with both Ba-O layer and Cu-O layer of Ba 2 YCu 3 O 7-x

  16. PIXE and RBS investigation of growth phases of ultra-thin chemical bath deposited CdS films

    International Nuclear Information System (INIS)

    Duncan, P.C.; Hinckley, S.; Gluszak, E.A.; Dytlewski, N.

    2002-01-01

    Polycrystalline CdS films, with thicknesses typically 20-180 nm, have been chemically deposited on glass substrates using an ammonia-cadmium-thiourea reaction solution. Film elemental composition, thickness and microstructure have been examined using proton-induced X-ray emission, Rutherford backscattering and atomic force microscopy. Analysis indicates that the stability of the deposition temperature plays a critical role in CdS film growth and composition. Films deposited with high temperature stability (60±0.5 deg. C) show a consistent 1:1 Cd:S atomic ratio for all stages of film growth, and have good substrate adhesion. Films deposited with lower temperature stability (60±4 deg. C) show initial high S concentrations, followed by a rapid increase in Cd concentration, until a final 1.2:1 Cd:S ratio is achieved. A mechanism is proposed to explain this difference in film composition and properties

  17. Growth of cuprate high temperature superconductor thin films

    Directory of Open Access Journals (Sweden)

    H-U Habermeier

    2006-09-01

    Full Text Available   This paper reviews briefly the development of physical vapour deposition based HTS thin film preparation technologies to today’s state-of-the-art methods. It covers the main trends of in-situ process and growth control. The current activities to fabricate tapes for power applications as well as to tailor interfaces in cuprate are described. Some future trends in HTS thin film research, both for science as well as application driven activities are outlined.

  18. Liquid phase epitaxial growth of heterostructured hierarchical MOF thin films

    KAUST Repository

    Chernikova, Valeriya

    2017-05-10

    Precise control of epitaxial growth of MOF-on-MOF thin films, for ordered hierarchical tbo-type structures is demonstrated. The heterostructured MOF thin film was fabricated by successful sequential deposition of layers from two different MOFs. The 2-periodic layers, edge-transitive 4,4-square lattices regarded as supermolecular building layers, were commendably cross-linked using a combination of inorganic/organic and organic pillars.

  19. Substrate heater for the growth of epitaxial silicon films

    Science.gov (United States)

    Deming, Matthew; Varhue, Walter; Adams, Edward; Lavoie, Mark

    1999-03-01

    The single wafer processing of epitaxial Si films requires that special attention be paid to the design of the substrate heater assembly. This document describes the evolution and testing of an in situ heater used to deposit epitaxial Si films at temperatures as high as 700 °C. One problem encountered was the production of excessive levels of ultraviolet radiation which contributed to the desorption of water vapor from the vacuum chamber walls during the in situ cleaning process. A second problem involved the formation of a molybdenum containing film that poisoned epitaxial growth. A final proven in situ heater design is presented which avoids these problems.

  20. The crack growth mechanism in asphaltic mixes

    NARCIS (Netherlands)

    Jacobs, M.M.J.; Hopman, P.C.; Molenaar, A.A.A.

    1995-01-01

    The crack growth mechanism in asphalt concrete (Ac) mixes is studied. In cyclic tests on several asphaltic mixes crack growth is measured, both with crack foils and with cOD-gauges. It is found that crack growth in asphaltic mixes is described by three processes which are parallel in time: cohesive

  1. Advances in pulsed laser deposition growth of nitride thin films

    Science.gov (United States)

    Fernandez, Felix E.; Pumarol, Manuel; Martinez, Antonio; Jia, Weiyi; Wang, Yanyung; Rodriguez, Edgardo; Mourad, Houssam A.

    1999-07-01

    Pulsed laser deposition of nitride semiconductor films offers an alternative to more usual techniques, such as MOCVD and MBE. PLD can produce good quality films at reduced growth temperatures. Rapid progress has been achieved in the laser few years, including demonstrations of epitaxial growth of GaN directly on sapphire. Work on PLD of direct- transition III- nitrides is briefly reviewed and our recent results for these materials are presented. Growth of these nitrides requires provision of nitrogen in a reactive form, which is usually supplied by NH3 gas flow. With the approach described here, reactive nitrogen is provided in an atomic beam, which has the advantage of reducing dependence on substrate temperature to surmount the kinetic energy barrier for formation, while eliminating a source of hydrogen during growth. Films grown from ceramic GaN targets are compared with those grown from liquid Ga. The latter method can offer better control of unintentional doping. InN films were also grown directly from In metal targets, with very good results in term so stoichiometry and crystalline quality. AlN films were grown from ceramic AlN targets, with excellent texture at reduced temperatures. Results are presented for crystal structure, composition and surface morphology. Optical properties were studied by transmission and luminescence spectroscopy.

  2. Single crystalline metal films as substrates for graphene growth

    Energy Technology Data Exchange (ETDEWEB)

    Zeller, Patrick; Henss, Ann-Kathrin; Wintterlin, Joost [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen (Germany); Weinl, Michael; Schreck, Matthias [Institut fuer Physik, Universitaet Augsburg (Germany); Speck, Florian; Ostler, Markus [Lehrstuhl fuer Technische Physik, Universitaet Erlangen-Nuernberg, Erlangen (Germany); Institut fuer Physik, Technische Universitaet Chemnitz (Germany); Seyller, Thomas [Institut fuer Physik, Technische Universitaet Chemnitz (Germany)

    2017-11-15

    Single crystalline metal films deposited on YSZ-buffered Si(111) wafers were investigated with respect to their suitability as substrates for epitaxial graphene. Graphene was grown by CVD of ethylene on Ru(0001), Ir(111), and Ni(111) films in UHV. For analysis a variety of surface science methods were used. By an initial annealing step the surface quality of the films was strongly improved. The temperature treatments of the metal films caused a pattern of slip lines, formed by thermal stress in the films, which, however, did not affect the graphene quality and even prevented wrinkle formation. Graphene was successfully grown on all three types of metal films in a quality comparable to graphene grown on bulk single crystals of the same metals. In the case of the Ni(111) films the originally obtained domain structure of rotational graphene phases could be transformed into a single domain by annealing. This healing process is based on the control of the equilibrium between graphene and dissolved carbon in the film. For the system graphene/Ni(111) the metal, after graphene growth, could be removed from underneath the epitaxial graphene layer by a pure gas phase reaction, using the reaction of CO with Ni to give gaseous Ni(CO){sub 4}. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Physical, mechanical and antimicrobial properties of starch films incorporated with ε-poly-L-lysine.

    Science.gov (United States)

    Zhang, Liming; Li, Ruichao; Dong, Feng; Tian, Aiying; Li, Zhengjun; Dai, Yujie

    2015-01-01

    Starch/ε-poly-L-lysine (ε-PL) composite films were prepared by combining 4% (w/v) gelatinized cornstarch and varying the level of ε-PL. The physical, mechanical and antimicrobial properties of these films were investigated. Fourier-transform infrared spectra (FT-IR) showed that the carbonyl group stretching vibration band of the ε-PL molecule shifted from 1646 cm(-1) to 1673 cm(-1) in the composite films. Differential scanning calorimetry (DSC) results indicated that there were sharp endothermal peaks at 215-230 °C for the composite films. These results indicated that there was an intense interaction between the two components. The films incorporated with ε-PL showed a higher tensile strength (TS) and elongation-at-break (E) than those of the starch film alone. These composite films exhibited effective inhibition against Escherichia coli and Bacillus subtilis, films containing 2% (w/w) ε-PL effectively suppressed the growth of the tested microbes (Pstarch/ε-PL films showed a low inhibitory effect on Aspergillus niger. This antimicrobial trend of the composite films was in agreement with the results of free ε-PL. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Low Temperature Growth of Nanostructured Diamond Films on Metals

    Science.gov (United States)

    Baker, Paul A.; Catledge, Shane A.; Vohra, Yogesh K.

    2001-01-01

    The field of nanocrystalline diamond and tetrahedral amorphous carbon films has been the focus of intense experimental activity in the last few years for applications in field emission display devices, optical windows, and tribological coatings, The choice of substrate used in most studies has typically been silicon. For metals, however, the thermal expansion mismatch between the diamond film and substrate gives rise to thermal stress that often results in delamination of the film. To avoid this problem in conventional CVD deposition low substrate temperatures (less than 700 C) have been used, often with the incorporation of oxygen or carbon monoxide to the feedgas mixture. Conventionally grown CVD diamond films are also rough and would require post-deposition polishing for most applications. Therefore, there is an obvious need to develop techniques for deposition of well-adhered, smooth nano-structured diamond films on metals for various tribological applications. In our work, nanostructured diamond films are grown on a titanium alloy substrate using a two-step deposition process. The first step is performed at elevated temperature (820 C) for 30 minutes using a H2/CH4/N2 gas mixture in order to grow a thin (approx. 600 nm) nanostructured diamond layer and improve film adhesion. The remainder of the deposition involves growth at low temperature (less than 600 C) in a H2/CH4/O2 gas mixture. Laser reflectance Interferometry (LRI) pattern during growth of a nanostructured diamond film on Ti-6Al-4V alloy. The first 30 minutes are at a high temperature of 820 C and the rest of the film is grown at a low temperature of 580 T. The fringe pattern is observed till the very end due to extremely low surface roughness of 40 nm. The continuation of the smooth nanostructured diamond film growth during low temperature deposition is confirmed by in-situ laser reflectance interferometry and by post-deposition micro-Raman spectroscopy and surface profilometry. Similar experiments

  5. Thin Films of Quasicrystals: Optical, Electronic, and Mechanical Properties

    Science.gov (United States)

    Symko, Orest G.

    1998-03-01

    In order to extend some of the unusual properties of quasicrystals toward practical applications and to study fundamental aspects of these properties, we have developed a technology for the deposition of high quality thin films of quasicrystals on a variety of substrates. Mechanical support for the thin films is provided by the substrate as bulk quasicrystals are brittle. We have applied the thin films to studies of their optical, electrical, and mechanical properties as well as to coatings of biomedical devices. An important characteristic of a quasicrystal is its pseudogap in the electronic density of states; it is determined directly from optical transmission measurements. Optical and mechanical characteristics of the thin films provide strong support for the cluster nature of quasicrystals and emphasize their importance for coatings. When used in biomedical devices, thin film quasicrystalline coatings show remarkable strength, low friction, and non-stick behavior. This work was in collaboration with W. Park, E. Abdel-Rahman, and T. Klein.

  6. Optical properties of organic semiconductor thin films. Static spectra and real-time growth studies

    Energy Technology Data Exchange (ETDEWEB)

    Heinemeyer, Ute

    2009-07-20

    The aim of this work was to establish the anisotropic dielectric function of organic thin films on silicon covered with native oxide and to study their optical properties during film growth. While the work focuses mainly on the optical properties of Diindenoperylene (DIP) films, also the optical response of Pentacene (PEN) films during growth is studied for comparison. Spectroscopic ellipsometry and differential reflectance spectroscopy are used to determine the dielectric function of the films ex-situ and in-situ, i.e. in air and in ultrahigh vacuum. Additionally, Raman- and fluorescence spectroscopy is utilized to characterize the DIP films serving also as a basis for spatially resolved optical measurements beyond the diffraction limit. Furthermore, X-ray reflectometry and atomic force microscopy are used to determine important structural and morphological film properties. The absorption spectrum of DIP in solution serves as a monomer reference. The observed vibronic progression of the HOMO-LUMO transition allows the determination of the Huang-Rhys parameter experimentally, which is a measure of the electronic vibrational coupling. The corresponding breathing modes are measured by Raman spectroscopy. The optical properties of DIP films on native oxide show significant differences compared to the monomer spectrum due to intermolecular interactions. First of all, the thin film spectra are highly anisotropic due to the structural order of the films. Furthermore the Frenkel exciton transfer is studied and the energy difference between Frenkel and charge transfer excitons is determined. Real-time measurements reveal optical differences between interfacial or surface molecules and bulk molecules that play an important role for device applications. They are not only performed for DIP films but also for PEN films. While for DIP films on glass the appearance of a new mode is visible, the spectra of PEN show a pronounced energy red-shift during growth. It is shown how the

  7. Enhanced Graphene Mechanical Properties through Ultrasmooth Copper Growth Substrates.

    Science.gov (United States)

    Griep, Mark H; Sandoz-Rosado, Emil; Tumlin, Travis M; Wetzel, Eric

    2016-03-09

    The combination of extraordinary strength and stiffness in conjunction with exceptional electronic and thermal properties in lightweight two-dimensional materials has propelled graphene research toward a wide array of applications including flexible electronics and functional structural components. Tailoring graphene's properties toward a selected application requires precise control of the atomic layer growth process, transfer, and postprocessing procedures. To date, the mechanical properties of graphene are largely controlled through postprocess defect engineering techniques. In this work, we demonstrate the role of varied catalytic surface morphologies on the tailorability of subsequent graphene film quality and breaking strength, providing a mechanism to tailor the physical, electrical, and mechanical properties at the growth stage. A new surface planarization methodology that results in over a 99% reduction in Cu surface roughness allows for smoothness parameters beyond that reported to date in literature and clearly demonstrates the role of Cu smoothness toward a decrease in the formation of bilayer graphene defects, altered domain sizes, monolayer graphene sheet resistance values down to 120 Ω/□ and a 78% improvement in breaking strength. The combined electrical and mechanical enhancements achieved through this methodology allows for the direct growth of application quality flexible transparent conductive films with monolayer graphene.

  8. Perovskite Oxide Thin Film Growth, Characterization, and Stability

    Science.gov (United States)

    Izumi, Andrew

    Studies into a class of materials known as complex oxides have evoked a great deal of interest due to their unique magnetic, ferroelectric, and superconducting properties. In particular, materials with the ABO3 perovskite structure have highly tunable properties because of the high stability of the structure, which allows for large scale doping and strain. This also allows for a large selection of A and B cations and valences, which can further modify the material's electronic structure. Additionally, deposition of these materials as thin films and superlattices through techniques such as pulsed laser deposition (PLD) results in novel properties due to the reduced dimensionality of the material. The novel properties of perovskite oxide heterostructures can be traced to a several sources, including chemical intermixing, strain and defect formation, and electronic reconstruction. The correlations between microstructure and physical properties must be investigated by examining the physical and electronic structure of perovskites in order to understand this class of materials. Some perovskites can undergo phase changes due to temperature, electrical fields, and magnetic fields. In this work we investigated Nd0.5Sr 0.5MnO3 (NSMO), which undergoes a first order magnetic and electronic transition at T=158K in bulk form. Above this temperature NSMO is a ferromagnetic metal, but transitions into an antiferromagnetic insulator as the temperature is decreased. This rapid transition has interesting potential in memory devices. However, when NSMO is deposited on (001)-oriented SrTiO 3 (STO) or (001)-oriented (LaAlO3)0.3-(Sr 2AlTaO6)0.7 (LSAT) substrates, this transition is lost. It has been reported in the literature that depositing NSMO on (110)-oriented STO allows for the transition to reemerge due to the partial epitaxial growth, where the NSMO film is strained along the [001] surface axis and partially relaxed along the [11¯0] surface axis. This allows the NSMO film enough

  9. Optical and mechanical properties of diamond like carbon films ...

    Indian Academy of Sciences (India)

    The mechanical properties such as hardness and elastic modulus were measured by load depth sensing indentation technique. The DLC film deposited at –100 V bias exhibit high hardness (∼ 19 GPa), high elastic modulus (∼ 160 GPa) and high refractive index (∼ 2.16–2.26) as compared to films deposited at –60 V and ...

  10. Phosphorus introduction mechanism in electrodeposited cobalt films

    International Nuclear Information System (INIS)

    Kravtchenko, Jean-Francois

    1973-01-01

    The cathodic reduction of hypophosphite, phosphite and phosphate ions was studied using chrono-potentiometry and voltammetry. Then cobalt was deposited at constant current from a bath containing one of these three compounds. The current, while giving an electrodeposition of cobalt, also enhances at the same time a chemical deposition of cobalt. It is shown that high coercive forces in cobalt films are much more related to this chemical deposition than to the simple fact that the films contain some phosphorus. (author) [fr

  11. Monolithic growth of partly cured polydimethylsiloxane thin film layers

    DEFF Research Database (Denmark)

    Yu, Liyun; Skov, Anne Ladegaard

    2014-01-01

    at different curing times. The monolithic films are investigated by rheology, scanning electron microscope, mechanical testing, dielectric relaxation spectroscopy, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology, mechanical and dielectric properties, as well...... to enable interlayer crosslinking reactions either by application of an adhesion promoter or by ensuring that there are reactive, complementary sites available on the two surfaces. Polydimethylsiloxane (PDMS) is a widely used polymer for DEAPs. In this work, two-layered PDMS films are adhered together...... as thermal stabilities of the bilayer elastomer films are observed to change with the curing time of the monolayers before lamination. The objective of this work is to create adhesion of two layers without destroying the original viscoelastic properties of the PDMS films, and hence enable, for example...

  12. Incorporation mechanism for doping of metal ions into a passivating film at the lithium/thionyl chloride interface

    Science.gov (United States)

    Danilov, V. G.; Shikin, V. I.

    1993-05-01

    Effects of iron and titanium ions on corrosion processes of lithium in thionyl chloride electrolytes have been studied. Laws for the growth of the passivating film on the type and concentration of doped ions have been established, and equations for these are suggested. A stepwise mechanism of dopant incorporation into passivating film structure is presented.

  13. Incorporation mechanism for doping of metal ions into a passive film at the lithium/thionyl chloride interface

    Energy Technology Data Exchange (ETDEWEB)

    Danilov, V.G. (Siberian Inst. of Tech., Krasnoyarsk (Russian Federation). Lab. of Electrochemistry); Shilkin, V.I. (Siberian Inst. of Tech., Krasnoyarsk (Russian Federation). Lab. of Electrochemistry)

    1993-05-01

    Effects of iron and titanium ions on corrosion processes of lithium in thionyl chloride electrolytes have been studied. Laws for the growth of the passivating film on the type and concentration of doped ions have been established, and equations for these are suggested. A stepwise mechanism of dopant incorporation into passivating film structure is presented. (orig.)

  14. High throughput growth and characterization of thin film materials

    Science.gov (United States)

    Mao, Samuel S.

    2013-09-01

    It usually takes more than 10 years for a new material from initial research to its first commercial application. Therefore, accelerating the pace of discovery of new materials is critical to tackling challenges in areas ranging from clean energy to national security. As discovery of new materials has not kept pace with the product design cycles in many sectors of industry, there is a pressing need to develop and utilize high throughput screening and discovery technologies for the growth and characterization of new materials. This article presents two distinctive types of high throughput thin film material growth approaches, along with a number of high throughput characterization techniques, established in the author's group. These approaches include a second-generation "discrete" combinatorial semiconductor discovery technology that enables the creation of arrays of individually separated thin film semiconductor materials of different compositions, and a "continuous" high throughput thin film material screening technology that enables the realization of ternary alloy libraries with continuously varying elemental ratios.

  15. Correlation between texture and mechanical stress durability of thin aluminum films

    Energy Technology Data Exchange (ETDEWEB)

    Nüssl, R., E-mail: rudolf.nuessl@uct.ac.za [Institut für Physik, Universität der Bundeswehr München, Werner-Heisenberg-Weg 39, 85579 Neubiberg (Germany); Jewula, T.; Ruile, W. [TDK Corporation, Systems, Acoustics, Waves Business Group, Anzingerstraße 13, 81617 Munich (Germany); Sulima, T.; Hansch, W. [Institut für Physik, Universität der Bundeswehr München, Werner-Heisenberg-Weg 39, 85579 Neubiberg (Germany)

    2014-04-01

    In this article, differently textured aluminum (Al) metallizations of surface acoustic wave (SAW) devices have been exposed to cyclic mechanical stress in order to investigate a potential correlation between their texture and their mechanical stress durability. Samples of SAW devices with differently textured Al thin film electrodes have been manufactured, and texture measurements have been carried out on all samples with electron backscatter diffraction. Subsequently, the SAW devices have been operated at heavy electrical load until a defined mechanical fatigue of its Al electrodes occurred. SAW devices with highly textured Al electrodes showed almost 20 times higher power durability than SAW devices with untextured Al electrodes. We show that this increase in electrical power durability has to be fully attributed to the strongly enhanced mechanical stress durability of highly textured Al films. Furthermore, a positive correlation between the Al films' texture and its electrical conductivity has been found. - Highlights: • We show highly textured growth of thin Al films on a clean, monocrystalline LiTaO{sub 3} • Highly textured Al growth gets disturbed by prior photolithographic process steps • Power durability of a SAW device increases with texture of its metallization • Texture and mechanical stress durability of a thin Al film are tightly correlated.

  16. solution growth and characterization of copper oxide thin films ...

    African Journals Online (AJOL)

    Thin films of copper oxide (CuO) were grown on glass slides by using the solution growth technique. Copper cloride (CuCl ) and potassium telluride (K T O ) were used. Buffer 2 2e 3 solution was used as complexing agent. The solid state properties and optical properties were obtained from characterization done using PYE ...

  17. PEALD AlN: Controlling growth and film crystallinity

    NARCIS (Netherlands)

    Banerjee, Sourish; Aarnink, Antonius A.I.; van de Kruijs, Robbert Wilhelmus Elisabeth; Kovalgin, Alexeij Y.; Schmitz, Jurriaan

    2015-01-01

    We report on the growth kinetics and material properties of aluminium nitride (AlN) films deposited on Si(111), with plasma enhanced atomic layer deposition (PEALD). Tri-methyl aluminium (TMA) and NH3-plasma were used as the precursors. The ALD window was identified in terms of the process

  18. Epitaxial growth of zinc oxide thin films on silicon

    International Nuclear Information System (INIS)

    Jin Chunming; Narayan, Roger; Tiwari, Ashutosh; Zhou Honghui; Kvit, Alex; Narayan, Jagdish

    2005-01-01

    Epitaxial zinc oxide thin films were grown on Si(111) using aluminum nitride and magnesium oxide/titanium nitride buffer layers. The resultant films were examined using transmission electron microscopy, X-ray diffraction, electrical conductivity, and photoluminescence spectroscopy. The following epitaxial relationships were observed in the ZnO/AlN/Si(111) heterostructure: ZnO[0001] parallel AlN[0001] parallel Si[111] along the growth direction, and ZnO[21-bar 1-bar 0] parallel AlN[21-bar 1-bar 0] parallel Si[011-bar] along the in-plane direction. Domain-matching epitaxial growth of TiN on Si(111) substrate allows successful epitaxial growth of MgO and ZnO layers in a ZnO/MgO/TiN/Si(111) heterostructure. The epitaxial relationships observed for this heterostructure were ZnO[0001] parallel MgO/TiN/Si[111] along the growth direction and ZnO[21-bar 1-bar 0] parallel MgO/TiN/Si[011-bar] along in-plane direction. The resultant ZnO films demonstrate excellent electrical and optical properties. ZnO thin films exhibit extremely bright ultraviolet luminescence with relatively weak green-band emission

  19. Morphology reliance of cobalt sulfide thin films: A chemo-thermo-mechanical perception

    Energy Technology Data Exchange (ETDEWEB)

    Kamble, S.S. [Thin Film & Solar Studies Research Laboratory, Solapur University, Solapur 413 255, M.S. (India); Sikora, A. [Electrotechnical Institute, Division of Electrotechnology & Materials Science, ul. M Skłodowskiej-Curie 55/61, 50-369 Wroclaw (Poland); Pawar, S.T. [Thin Film & Solar Studies Research Laboratory, Solapur University, Solapur 413 255, M.S. (India); Kambale, R.C. [Department of Physics, University of Pune, Ganeshkhind, Pune 411 007, M.S. (India); Maldar, N.N. [School of Chemical Sciences, Solapur University, Solapur 413 255, M.S. (India); Deshmukh, L.P., E-mail: laldeshmukh@gmail.com [Thin Film & Solar Studies Research Laboratory, Solapur University, Solapur 413 255, M.S. (India)

    2015-05-15

    Highlights: • Optimized heterogeneous growth process for the deposition of CoS thin films. • As-obtained CoS thin films exhibit hexagonal crystal structure. • Optimized CoS thin films were Co{sup 2+} rich in nature. • Magnetic force microscopy revealed randomly scattered magnetic constellations. - Abstract: We report onto the morphology dependency of CoS thin films by studying the role of mechanical agitation, thermal assistance and deposition duration in an aqueous alkaline bath (pH = 9 ± 0.1). The deposition of CoS thin films was carried out at different mechanical stirring rates, deposition temperatures and times. As-optimized CoS thin film were of polycrystalline nature and exhibited hexagonal crystal structure. Co{sup 2+} rich nature (≈85%) of optimistically grown thin film was detected. Complex multifaceted webbed network of as-grown elongated and threaded into each other CoS crystals was observed through a scanning electron microscope. Surface morphology was further studied by means of an atomic force microscopy. Existence of magnetic domains was marked in the magnetic force microscopy. As-grown CoS thin films were having transmission index of 0.5 with a band gap of ≈1.59 eV.

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

    Science.gov (United States)

    Liu, Sijun; Li, Yong; Li, Lin

    2017-03-15

    This work aims to study how three kinds of nanofillers: graphene oxide (GO), ammonia functionalized graphene oxide (AGO), and triethoxylpropylaminosilane functionalized silica, can affect stability and mechanical strength of sodium alginate (SA) composite films. The filler/sodium alginate (SA) solutions were first studied by rheology to reveal effects of various fillers on zero shear viscosity η 0 . SA composite films were then prepared by a solution mixing-evaporation method. The structure, morphology and properties of SA composite films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), contact angle and mechanical testing. Compared to GO and silica, the presence of AGO significantly improved the interaction between AGO and SA, which led to the increase in stability and mechanical strength of the resulting SA composite films. The tensile strength and elongation at break of AGO/SA composite film at 3wt% AGO loading were increased by 114.9% and 194.4%, respectively, in contrast to pure SA film. Furthermore, the stability of AGO/SA composite films at high temperatures and in a wet environment were better than that of silica/SA and GO/SA composite films. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Edge Effects on Growth of Ordered Stress Relief Patterns in Free Sustained Aluminum Films

    International Nuclear Information System (INIS)

    Sen-Jiang, Yu; Miao-Gen, Chen; Yong-Ju, Zhang

    2010-01-01

    An unusual form of ordered stress relief patterns is observed in a nearly free sustained aluminum film system deposited on liquid substrates by the thermal evaporation method. The edge effects on the growth of the ordered patterns are systematically studied. It is found that the patterns initiate from the film edges, preexisting ordered patterns, or other imperfections of the film. When the patterns extend in the film regions, they decay gradually and finally disappear. If they develop along the boundaries, however, the sizes are almost unchanged over several millimeters. The stress relief patterns look like rectangular waves in appearance, which are proven to evolve from sinusoidal to triangular waves gradually. The morphological evolution can be well explained by the general theory of buckling of plates. (condensed matter: structure, mechanical and thermal properties)

  2. Amorphous carbon film growth on Si: Correlation between stress and generation of defects into the substrate

    International Nuclear Information System (INIS)

    Brusa, R.S.; Macchi, C.; Mariazzi, S.; Karwasz, G.P.; Laidani, N.; Bartali, R.; Anderle, M.

    2005-01-01

    Amorphous carbon films of several thicknesses were prepared by graphite sputtering on crystalline silicon substrate. The samples were depth profiled with positron annihilation spectroscopy for open-volume measurements and characterized for their residual internal stress. It was found that after film growth the substrate presents vacancy-like defects decorated by oxygen in a layer extending in the substrate by several tens of nanometers beyond the film/Si interface. The width of the defected layer and the decoration of vacancy-like defects are directly and inversely proportional to the measured intensity of the residual stress, respectively. These findings indicate the existence of a relaxation mechanism of the stress in the films that involves deeply the substrate. The decorated vacancy-like defects are suggested to be bounded to dislocations induced in the substrate by the stress relaxation

  3. The influence of energetic bombardment on the structure formation of sputtered zinc oxide films. Development of an atomistic growth model and its application to tailor thin film properties

    Energy Technology Data Exchange (ETDEWEB)

    Koehl, Dominik

    2011-02-17

    The focus of this work is the investigation of the growth of zinc oxide (ZnO) thin films. It is demonstrated that with a modified, ion beam assisted sputtering (IBAS) process, zinc oxide films can be deposited which exhibit a markedly improved crystalline order. Furthermore, it is demonstrated that intense energetic oxygen ion bombardment can be utilized to change film texture from the typical (002)-self-texture to an a-axis texture where the (002)-planes are perpendicular to the substrate surface. An understanding of the underlying mechanisms is developed which also facilitates a more detailed understanding of the action of ion bombardment during zinc oxide film growth. It is shown that zinc oxide films are susceptible to the influence of ion bombardment particularly in the nucleation regime of growth and that this finding is generally true for all observed structural changes induced by ion bombardment with various species, energies and flux densities. It is demonstrated not only that the initial growth stage plays an important role in the formation of a preferred growth orientation but also that the action of texture forming mechanisms in subsequent growth stages is comparatively weak. (orig.)

  4. The influence of energetic bombardment on the structure formation of sputtered zinc oxide films. Development of an atomistic growth model and its application to tailor thin film properties

    International Nuclear Information System (INIS)

    Koehl, Dominik

    2011-01-01

    The focus of this work is the investigation of the growth of zinc oxide (ZnO) thin films. It is demonstrated that with a modified, ion beam assisted sputtering (IBAS) process, zinc oxide films can be deposited which exhibit a markedly improved crystalline order. Furthermore, it is demonstrated that intense energetic oxygen ion bombardment can be utilized to change film texture from the typical (002)-self-texture to an a-axis texture where the (002)-planes are perpendicular to the substrate surface. An understanding of the underlying mechanisms is developed which also facilitates a more detailed understanding of the action of ion bombardment during zinc oxide film growth. It is shown that zinc oxide films are susceptible to the influence of ion bombardment particularly in the nucleation regime of growth and that this finding is generally true for all observed structural changes induced by ion bombardment with various species, energies and flux densities. It is demonstrated not only that the initial growth stage plays an important role in the formation of a preferred growth orientation but also that the action of texture forming mechanisms in subsequent growth stages is comparatively weak. (orig.)

  5. Dynamic mechanical thermal analysis of hypromellose 2910 free films.

    Science.gov (United States)

    Cespi, Marco; Bonacucina, Giulia; Mencarelli, Giovanna; Casettari, Luca; Palmieri, Giovanni Filippo

    2011-10-01

    It is common practice to coat oral solid dosage forms with polymeric materials for controlled release purposes or for practical and aesthetic reasons. Good knowledge of thermo-mechanical film properties or their variation as a function of polymer grade, type and amount of additives or preparation method is of prime importance in developing solid dosage forms. This work focused on the dynamic mechanical thermal characteristics of free films of hypromellose 2910 (also known as HPMC), prepared using three grades of this polymer from two different manufacturers, in order to assess whether polymer chain length or origin affects the mechanical or thermo-mechanical properties of the final films. Hypromellose free films were obtained by casting their aqueous solutions prepared at a specific concentrations in order to obtain the same viscosity for each. The films were stored at room temperature until dried and then examined using a dynamic mechanical analyser. The results of the frequency scans showed no significant differences in the mechanical moduli E' and E″ of the different samples when analysed at room temperature; however, the grade of the polymer affected material transitions during the heating process. Glass transition temperature, apparent activation energy and fragility parameters depended on polymer chain length, while the material brand showed little impact on film performance. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Heterojunction Effect in Weak Epitaxy Growth Thin Films Investigated by Kelvin Probe Force Microscopy

    International Nuclear Information System (INIS)

    Hai-Chao, Huang; Hai-Bo, Wang; Dong-Hang, Yan

    2010-01-01

    We investigate the heterojunction effect between para-sexiphenyl (p-6P) and copper phthalocyanine (CuPc) using Kelvin probe force microscopy. CuPc films are grown on the inducing layer p-6P by a weak epitaxy growth technique. The surface potential images of Kelvin probe force microscopy indicate the band bending in CuPc, which reduces grain boundary barriers and lead to the accumulation of holes in the CuPc layer. The electrical potential distribution on the surface of heterojunction films shows negligible grain boundary barriers in the CuPc layers. The relation between band bending and grain boundary barrier in the weak epitaxy growth thin films is revealed. (condensed matter: structure, mechanical and thermal properties)

  7. Low temperature CVD growth of ultrathin carbon films

    Directory of Open Access Journals (Sweden)

    Chao Yang

    2016-05-01

    Full Text Available We demonstrate the low temperature, large area growth of ultrathin carbon films by chemical vapor deposition under atmospheric pressure on various substrates. In particularly, uniform and continuous carbon films with the thickness of 2-5 nm were successfully grown at a temperature as low as 500 oC on copper foils, as well as glass substrates coated with a 100 nm thick copper layer. The characterizations revealed that the low-temperature-grown carbon films consist on few short, curved graphene layers and thin amorphous carbon films. Particularly, the low-temperature grown samples exhibited over 90% transmittance at a wavelength range of 400-750 nm and comparable sheet resistance in contrast with the 1000oC-grown one. This low-temperature growth method may offer a facile way to directly prepare visible ultrathin carbon films on various substrate surfaces that are compatible with temperatures (500-600oC used in several device processing technologies.

  8. Magnesium growth in magnesium deuteride thin films during deuterium desorption

    Energy Technology Data Exchange (ETDEWEB)

    Checchetto, R., E-mail: riccardo.checchetto@unitn.it [Dipartimento di Fisica and CNISM, Università di Trento, Via Sommarive 14, I-38123 Trento (Italy); Miotello, A. [Dipartimento di Fisica and CNISM, Università di Trento, Via Sommarive 14, I-38123 Trento (Italy); Mengucci, P.; Barucca, G. [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Università Politecnica delle Marche, I-60131 Ancona (Italy)

    2013-12-15

    Highlights: ► Highly oriented Pd-capped magnesium deuteride thin films. ► The MgD{sub 2} dissociation was studied at temperatures not exceeding 100 °C. ► The structure of the film samples was analyzed by XRD and TEM. ► The transformation is controlled by the re-growth velocity of the Mg layers. ► The transformation is thermally activated, activation energy value of 1.3 ± 0.1 eV. -- Abstract: Pd- capped nanocrystalline magnesium thin films having columnar structure were deposited on Si substrate by e-gun deposition and submitted to thermal annealing in D{sub 2} atmosphere to promote the metal to deuteride phase transformation. The kinetics of the reverse deuteride to metal transformation was studied by Thermal Desorption Spectroscopy (TDS) while the structure of the as deposited and transformed samples was analyzed by X-rays diffraction and Transmission Electron Microscopy (TEM). In Pd- capped MgD{sub 2} thin films the deuteride to metal transformation begins at the interface between un-reacted Mg and transformed MgD{sub 2} layers. The D{sub 2} desorption kinetics is controlled by MgD{sub 2}/Mg interface effects, specifically the re-growth velocity of the Mg layers. The Mg re-growth has thermally activated character and shows an activation energy value of 1.3 ± 0.1 eV.

  9. Giant secondary grain growth in Cu films on sapphire

    Directory of Open Access Journals (Sweden)

    David L. Miller

    2013-08-01

    Full Text Available Single crystal metal films on insulating substrates are attractive for microelectronics and other applications, but they are difficult to achieve on macroscopic length scales. The conventional approach to obtaining such films is epitaxial growth at high temperature using slow deposition in ultrahigh vacuum conditions. Here we describe a different approach that is both simpler to implement and produces superior results: sputter deposition at modest temperatures followed by annealing to induce secondary grain growth. We show that polycrystalline as-deposited Cu on α-Al2O3(0001 can be transformed into Cu(111 with centimeter-sized grains. Employing optical microscopy, x-ray diffraction, and electron backscatter diffraction to characterize the films before and after annealing, we find a particular as-deposited grain structure that promotes the growth of giant grains upon annealing. To demonstrate one potential application of such films, we grow graphene by chemical vapor deposition on wafers of annealed Cu and obtain epitaxial graphene grains of 0.2 mm diameter.

  10. Electro-active bio-films: formation, characterization and mechanisms

    International Nuclear Information System (INIS)

    Parot, Sandrine

    2007-01-01

    Some bacteria, which are able to exchange electrons with a conductive material without mediator form on conductive surfaces electro-active bio-films. This bacterial property has been recently discovered (2001). Objectives of this work are to develop electro-active bio-films in various natural environments from indigenous flora, then through complementary electrochemical techniques (chrono-amperometry and cyclic voltammetry), to evaluate electro-activity of isolates coming from so-formed bio-films and to characterize mechanisms of electron transfer between bacteria and materials. First, electro-active bio-films have been developed under chrono-amperometry in garden compost and in water coming from Guyana mangrove. These bio-films were respectively able to use an electrode as electron acceptor (oxidation) or as electron donor (reduction). In compost, results obtained in chrono-amperometry and cyclic voltammetry suggest a two-step electron transfer: slow substrate consumption, then rapid electron transfer between bacteria and the electrode. Thereafter, the ability to reduce oxygen was demonstrated with cyclic voltammetry for facultative aerobic isolates from compost bio-films (Enterobacter spp. and Pseudomonas spp.) and for aerobic isolates obtained from marine electro-active bio-films (Roseobacter spp. in majority). Finally, bio-films inducing current increase in chrono-amperometry were developed in bioreactor with synthetic medium from a pure culture of isolates. Hence, for the first time, electro-activity of several anaerobic strains of Geobacter bremensis isolated from compost bio-films was highlighted. (author) [fr

  11. Growth of Ag thin films on ZnO(0 0 0 -1) investigated by AES and STM

    Energy Technology Data Exchange (ETDEWEB)

    Duriau, E. [Interuniversity Microelectronic Center (IMEC), SPDT-MCA, Kapeldreef 75, B-3001 Leuven (Belgium); Agouram, S. [Dpto. Fisica Aplicada y Electromagnetismo c/Dr. Moliner no. 50, 46100 Burjassot, Valencia (Spain); Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Morhain, C. [Centre de Recherche sur l' HeteroEpitaxie et ses Applications (CRHEA), CNRS, Rue Bernard Gregory, F-06560 Valbonne Sophia-Antipolis (France); Seldrum, T. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Sporken, R. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Dumont, J. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium)]. E-mail: jacques.dumont@fundp.ac.be

    2006-11-15

    The growth of Ag films on ZnO(0 0 0 -1) has been investigated by Auger electron spectroscopy (AES) and scanning tunneling microscopy (STM). A high density of islands is nucleated at the earliest stages of the growth. An upstepping mechanism causes these islands to coalesce while the uncovered fraction of the ZnO surface remains constant (30%)

  12. Conciliating surface superhydrophobicities and mechanical strength of porous silicon films

    Science.gov (United States)

    Wang, Fuguo; Zhao, Kun; Cheng, Jinchun; Zhang, Junyan

    2011-01-01

    Hydrophobic surfaces on Mechanical stable macroporous silicon films were prepared by electrochemical etching with subsequent octadecyltrichlorosilane (OTS) modification. The surface morphologies were controlled by current densities and the mechanical properties were adjusted by their corresponding porosities. Contrast with the smooth macroporous silicon films with lower porosities (34.1%) and microporous silicon with higher porosities (97%), the macroporous film with a rough three-dimension (3D) surface and a moderate pore to cross-section area ratio (37.8%, PSi2‧) exhibited both good mechanical strength (Yong' modulus, shear modulus and collapse strength are 64.2, 24.1 and 0.32 GPa, respectively) and surface superhydrophobicity (water contact angle is 158.4 ± 2° and sliding angle is 2.7 ± 1°). This result revealed that the surface hydrophobicities (or the surface roughness) and mechanical strength of porous films could be conciliated by pore to cross-section area ratios control and 3D structures construction. Thus, the superhydrophobic surfaces on mechanical stable porous films could be obtained by 3D structures fabrication on porous film with proper pore to cross-section area ratios.

  13. Diamond film growth with modification properties of adhesion between substrate and diamond film

    Directory of Open Access Journals (Sweden)

    Setasuwon P.

    2004-03-01

    Full Text Available Diamond film growth was studied using chemical vapor deposition (CVD. A special equipment was build in-house, employing a welding torch, and substrate holder with a water-cooling system. Acetylene and oxygen were used as combustion gases and the substrate was tungsten carbide cobalt. It was found that surface treatments, such as diamond powder scratching or acid etching, increase the adhesion and prevent the film peel-off. Diamond powder scratching and combined diamond powder scratching with acid etching gave the similar diamond film structure with small grain and slightly rough surface. The diamond film obtained with both treatments has high adhesion and can withstand internal stress better than ones obtained by untreated surface or acid etching alone. It was also found that higher substrate temperature produced smoother surface and more uniform diamond grain.

  14. Microstructure and mechanical behavior of thin films and inhomogeneous materials

    Science.gov (United States)

    Toivola, Yvete Aubrey

    In this work, processing-structure-property relationships of thin (˜1 mum) films are developed for materials with applications in microelectronics, microelectromechanical systems (MEMS), or magnetic data storage through experimental studies to optimize material properties and improve device performance and reliability. Variations in film microstructure were achieved through changes in deposition conditions, curing conditions, or through direct changes in material density or composition. Changes in material properties as a result of these (chemical, structural, or physical) modifications are quantified through experimental measurements. Changes in mechanical behavior are quantified through ("nano"-scale) instrumented depth-sensing indentation (DSI) experiments. Changes in material structure and composition are quantified by infrared spectroscopy, ellipsometry, ion beam analysis, scanning electron microscopy, and atomic force microscopy. Structure-properties relationships are developed for organosilicate-based dielectric materials for microelectronic interconnection arrays with a focus on maximizing film modulus and hardness while minimizing dielectric constant. Relationships between film properties and film structure with changes in deposition conditions are developed for low-pressure chemical vapor deposited silicon nitride films used in MEMS and microelectronics. Specifically, changes in film composition as a result of deposition conditions are related to changes in film stress. DSI is used to measure the contact responses of silica foam films and flexible magnetic data storage tape for which the microstructural inhomogeneities are comparable to the scale of the indentations. Images of residual indentation impressions are used to determine deformation mechanisms, and contact responses are interpreted by a new method. Differences in the deformation of magnetic data storage tape are quantified using DSI through previously developed deconvolution models and also

  15. Influence of substrate surfaces on the growth of organic films

    Science.gov (United States)

    Das, A.; Salvan, G.; Kampen, T. U.; Hoyer, W.; Zahn, D. R. T.

    2003-05-01

    3,4,9,10-Perylene tetracarboxylic dianhydride (PTCDA) films were grown by organic molecular beam deposition (OMBD) under UHV conditions on hydrogen terminated Si(1 0 0) and sulphur passivated GaAs(1 0 0) surfaces. X-ray diffraction (XRD), X-ray reflectivity (XRR), Raman spectroscopy, and atomic force microscopy (AFM) are employed to study the influence of substrate surfaces on the structural properties of the organic films. Both phases of PTCDA, α- and β-polymorphs, are found to grow on both substrates. The substrate surfaces determine the preferential growth of α- and β-phases of PTCDA crystals at room temperature.

  16. Morphology and grain structure evolution during epitaxial growth of Ag films on native-oxide-covered Si surface

    International Nuclear Information System (INIS)

    Hur, Tae-Bong; Kim, Hong Koo; Perello, David; Yun, Minhee; Kulovits, Andreas; Wiezorek, Joerg

    2008-01-01

    Epitaxial nanocrystalline Ag films were grown on initially native-oxide-covered Si(001) substrates using radio-frequency magnetron sputtering. Mechanisms of grain growth and morphology evolution were investigated. An epitaxially oriented Ag layer (∼5 nm thick) formed on the oxide-desorbed Si surface during the initial growth phase. After a period of growth instability, characterized as kinetic roughening, grain growth stagnation, and increase of step-edge density, a layer of nanocrystalline Ag grains with a uniform size distribution appeared on the quasi-two-dimensional layer. This hierarchical process of film formation is attributed to the dynamic interplay between incoming energetic Ag particles and native oxide. The cyclic interaction (desorption and migration) of the oxide with the growing Ag film is found to play a crucial role in the characteristic evolution of grain growth and morphology change involving an interval of grain growth stagnation

  17. The mathematics and mechanics of biological growth

    CERN Document Server

    Goriely, Alain

    2017-01-01

    This monograph presents a general mechanical theory for biological growth. It provides both a conceptual and a technical foundation for the understanding and analysis of problems arising in biology and physiology. The theory and methods is illustrated on a wide range of examples and applications. A process of extreme complexity, growth plays a fundamental role in many biological processes and is considered to be the hallmark of life itself. Its description has been one of the fundamental problems of life sciences, but until recently, it has not attracted much attention from mathematicians, physicists, and engineers. The author herein presents the first major technical monograph on the problem of growth since D’Arcy Wentworth Thompson’s 1917 book On Growth and Form. The emphasis of the book is on the proper mathematical formulation of growth kinematics and mechanics. Accordingly, the discussion proceeds in order of complexity and the book is divided into five parts. First, a general introduction on the pro...

  18. Concepts on Low Temperature Mechanical Grain Growth

    Energy Technology Data Exchange (ETDEWEB)

    Sharon, John Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Metallurgy and Materials Joining Dept.; Boyce, Brad Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Metallurgy and Materials Joining Dept.

    2013-11-01

    In metals, as grain size is reduced below 100nm, conventional dislocation plasticity is suppressed resulting in improvements in strength, hardness, and wears resistance. Existing and emerging components use fine grained metals for these beneficial attributes. However, these benefits can be lost in service if the grains undergo growth during the component’s lifespan. While grain growth is traditionally viewed as a purely thermal process that requires elevated temperature exposure, recent evidence shows that some metals, especially those with nanocrystalline grain structure, can undergo grain growth even at room temperature or below due to mechanical loading. This report has been assembled to survey the key concepts regarding how mechanical loads can drive grain coarsening at room temperature and below. Topics outlined include the atomic level mechanisms that facilitate grain growth, grain boundary mobility, and the impact of boundary structure, loading scheme, and temperature.

  19. Selective growth of ZnO thin film nanostructures: Structure, morphology and tunable optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Krishnakanth, Katturi Naga; Sunandana, C. S. [School of Physics, University of Hyderabad, Hyderabad-50046 (India); Rajesh, Desapogu, E-mail: rajesh.esapogu@gmail.com, E-mail: mperd@nus.edu.sg [School of Physics, University of Hyderabad, Hyderabad-50046 (India); Dept. of Mechanical Engineering, National University of Singapore (Singapore)

    2016-05-23

    The ZnO nanostructures (spherical, rod shape) have been successfully fabricated via a thermal evaporation followed by dip coating method. The pure, doped ZnO thin films were characterized by X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM) and UV-Vis spectroscopy, respectively. A possible growth mechanism of the spherical, rod shape ZnO nanostructures are discussed. XRD patterns revealed that all films consist of pure ZnO phase and were well crystallized with preferential orientation towards (002) direction. Doping by PVA, PVA+Cu has effective role in the enhancement of the crystalline quality and increases in the band gap.

  20. Mechanism of constitution liquid film migration

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Hongjun [Univ. of Alabama, Birmingham, AL (United States)

    1999-06-01

    Liquid film migration (LFM) in liquid phase sintering classically involves a large metastable liquid volume adjacent to solid, and migration occurs at an isolated solid-liquid (S-L) interface. Constitutional liquid film migration (CLFM), discovered in alloy 718, has major characteristics similar to those of LFM, except that the metastable liquid is from the constitutional liquation of precipitates on the grain boundary. The similarity between LFM and CLFM has led to the theory that coherency lattice strain responsible for LFM is also responsible for CLFM. The coherency strain hypothesis was tested in this study by evaluating whether the Hillert model of LFM would also apply for CLFM. Experimental results of CLFM in alloy 718 showed that migration velocity followed the trend predicted by the Hillert model. This indicates that the coherency strain hypothesis of LFM also applies for CLFM and that the coherency lattice strain responsible for LFM is also the driving force for CLFM.

  1. Growth dynamics of copper thin film deposited by soft-landing of size selected nanoclusters

    Science.gov (United States)

    Mondal, Shyamal; Chowdhury, Debasree; Barman, Pintu; Bhattacharyya, Satya Ranjan

    2017-12-01

    We investigate surface kinetic roughening of copper films grown on Si(1 0 0) substrates at room temperature by means of atomic force microscopy study. Films were deposited at various durations by soft landing of size selected ( 3 nm) nanoclusters using a state of the art nanocluster deposition system. The film growth exhibits two growth regimes with a crossover time of 40 min. In the first regime, surface morphologies show bimodal distribution and surface roughness shows a linear increase with growth exponent β = 0.14 ± 0.02. In the second regime, the height distribution becomes Gaussian and surface roughness shows a steep rise with high β value 0.83 ± 0.45. On the other hand, the roughness exponent α ranges from 0.68 ± 0.03 to 0.84 ± 0.01 for low to high deposition regimes. Estimated scaling exponent suggests the diffusion of clusters on substrate surface and shadowing effect play dominant role in growth mechanism of the nanostructured thin film. Contribution to the Topical Issue: "Dynamics of Systems at the Nanoscale", edited by Andrey Solov'yov and Andrei Korol.

  2. Effect of enhanced C2 growth chemistry on nanodiamond film deposition

    International Nuclear Information System (INIS)

    Teii, Kungen; Ikeda, Tomohiro

    2007-01-01

    A route to high-purity nanocrystalline diamond films from C 2 dimers and related mechanisms have been investigated by enhancing C 2 growth chemistry in Ar-rich microwave plasmas. Efficient C 2 production by direct dissociation from acetylene causes the micro- to nanocrystal transition with a low threshold Ar concentration of ∼70% and produces films of ∼20 nm grains with a distinct visible-Raman peak of diamond. C 2 grows nanodiamond on diamond surfaces but rarely initiates nucleation on foreign surfaces. The phase purity can be improved by increasing the dominance of nanodiamond growth from C 2 over nondiamond growth from CH x (x=0-3) and large radicals

  3. Surface scattering mechanisms of tantalum nitride thin film resistor.

    Science.gov (United States)

    Chen, Huey-Ru; Chen, Ying-Chung; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Chu, Tian-Jian; Shih, Chih-Cheng; Chuang, Nai-Chuan; Wang, Kao-Yuan

    2014-01-01

    In this letter, we utilize an electrical analysis method to develop a TaN thin film resistor with a stricter spec and near-zero temperature coefficient of resistance (TCR) for car-used electronic applications. Simultaneously, we also propose a physical mechanism mode to explain the origin of near-zero TCR for the TaN thin film resistor (TFR). Through current fitting, the carrier conduction mechanism of the TaN TFR changes from hopping to surface scattering and finally to ohmic conduction for different TaN TFRs with different TaN microstructures. Experimental data of current-voltage measurement under successive increasing temperature confirm the conduction mechanism transition. A model of TaN grain boundary isolation ability is eventually proposed to influence the carrier transport in the TaN thin film resistor, which causes different current conduction mechanisms.

  4. Mechanical protection of DLC films on fused silica slides

    Science.gov (United States)

    Nir, D.

    1985-01-01

    Measurements were made with a new test for improved quantitative estimation of the mechanical protection of thin films on optical materials. The mechanical damage was induced by a sand blasting system using spherical glass beads. Development of the surface damage was measured by the changes in the specular transmission and reflection, and by inspection using a surface profilometer and a scanning electron microscope. The changes in the transmittance versus the duration of sand blasting was measured for uncoated fused silica slides and coated ones. It was determined that the diamond like carbon films double the useful optical lifetime of the fused silica. Theoretical expressions were developed to describe the stages in surface deterioration. Conclusions were obtained for the SiO2 surface mechanism and for the film removal mechanism.

  5. Mechanical properties of N,N,N-trimethylchitosan chloride films

    Directory of Open Access Journals (Sweden)

    Douglas de Britto

    2005-06-01

    Full Text Available Films of chitosan and N,N,N-trimethylchitosan were cast from aqueous solutions. Chitosan was dissolved in 1% acetic acid while deionized water was the solvent for N,N,N-trimethylchitosan chloride. The resulting films presented different mechanical behaviors as evaluated by DMTA. The film of chitosan exhibited an elastic-type behavior while that of N,N,N-trimethylchitosan was typically viscous. No glass transition temperatures were observed; however, a discrete thermal transition was detected at 25 °C in the case of the N,N,N-trimethylchitosan.

  6. Elucidation of the electrochromic mechanism of nanostructured iron oxides films

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Lobato, M.A.; Martinez, Arturo I.; Castro-Roman, M. [Center for Research and Advanced Studies of the National Polytechnic Institute, Cinvestav Campus Saltillo, Carr. Saltillo-Monterrey Km. 13, Ramos Arizpe, Coah. 25900 (Mexico); Perry, Dale L. [Mail Stop 70A1150, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Zarate, R.A. [Departamento de Fisica, Facultad de Ciencias, Universidad Catolica del Norte, Casilla 1280, Antofagasta (Chile); Escobar-Alarcon, L. (Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico)

    2011-02-15

    Nanostructured hematite thin films were electrochemically cycled in an aqueous solution of LiOH. Through optical, structural, morphological, and magnetic measurements, the coloration mechanism of electrochromic iron oxide thin films was elucidated. The conditions for double or single electrochromic behavior are given in this work. During the electrochemical cycling, it was found that topotactic transformations of hexagonal crystal structures are favored; i.e. {alpha}-Fe{sub 2}O{sub 3} to Fe(OH){sub 2} and subsequently to {delta}-FeOOH. These topotactic redox reactions are responsible for color changes of iron oxide films. (author)

  7. Grain Growth in Nanocrystalline Mg-Al Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Kruska, Karen; Rohatgi, Aashish; Vemuri, Venkata Rama Ses; Kovarik, Libor; Moser, Trevor H.; Evans, James E.; Browning, Nigel D.

    2017-10-05

    An improved understanding of grain growth kinetics in nanocrystalline materials, and in metals and alloys in general, is of continuing interest to the scientific community. In this study, Mg - Al thin films containing ~10 wt.% Al and with 14.5 nm average grain size were produced by magnetron-sputtering and subjected to heat-treatments. The grain growth evolution in the early stages of heat treatment at 423 K (150 °C), 473 K (200 °C) and 573K (300 °C) was observed with transmission electron microscopy and analyzed based upon the classical equation developed by Burke and Turnbull. The grain growth exponent was found to be 7±2 and the activation energy for grain growth was 31.1±13.4 kJ/mol, the latter being significantly lower than in bulk Mg-Al alloys. The observed grain growth kinetics are explained by the Al supersaturation in the matrix and the pinning effects of the rapidly forming beta precipitates and possibly shallow grain boundary grooves. The low activation energy is attributed to the rapid surface diffusion which is dominant in thin film systems.

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

    Energy Technology Data Exchange (ETDEWEB)

    Vandentop, G.J.

    1990-07-01

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

  9. Piezoelectric actuated micro-resonators based on the growth of diamond on aluminum nitride thin films.

    Science.gov (United States)

    Hees, J; Heidrich, N; Pletschen, W; Sah, R E; Wolfer, M; Williams, O A; Lebedev, V; Nebel, C E; Ambacher, O

    2013-01-18

    Unimorph heterostructures based on piezoelectric aluminum nitride (AlN) and diamond thin films are highly desirable for applications in micro- and nanoelectromechanical systems. In this paper, we present a new approach to combine thin conductive boron-doped as well as insulating nanocrystalline diamond (NCD) with sputtered AlN films without the need for any buffer layers between AlN and NCD or polishing steps. The zeta potentials of differently treated nanodiamond (ND) particles in aqueous colloids are adjusted to the zeta potential of AlN in water. Thereby, the nucleation density for the initial growth of diamond on AlN can be varied from very low (10(8) cm(-2)), in the case of hydrogen-treated ND seeding particles, to very high values of 10(11) cm(-2) for oxidized ND particles. Our approach yielding high nucleation densities allows the growth of very thin NCD films on AlN with thicknesses as low as 40 nm for applications such as microelectromechanical beam resonators. Fabricated piezo-actuated micro-resonators exhibit enhanced mechanical properties due to the incorporation of boron-doped NCD films. Highly boron-doped NCD thin films which replace the metal top electrode offer Young's moduli of more than 1000 GPa.

  10. Models of WO x films growth during pulsed laser deposition at elevated pressures of reactive gas

    Science.gov (United States)

    Gnedovets, A. G.; Fominski, V. Y.; Nevolin, V. N.; Romanov, R. I.; Fominski, D. V.; Soloviev, A. A.

    2017-12-01

    The films of tungsten oxides were prepared by pulsed laser ablation of W target in a reactive gas atmosphere (air of laboratory humidity). Optical analysis and ion signal measurements for the laser plume allowed to recognise a threshold gas pressure that suppresses the deposition of non-scattered atomic flux from the plume. When the pressure exceeds about 40 Pa, the films grow due to the deposition of species that could be formed in collisions of W atoms with reactive molecules (e.g., O2). Kinetic Monte Carlo method was used for modelling film growth. Comparison of the model structures with the experimentally prepared films has shown that the growth mechanism of ballistic deposition at a pressure of 40 Pa could be changed on the diffusion limited aggregation at a pressure of ~100 Pa. Thus, a cauliflower structure of the film transformed to a web-like structure. For good correlation of experimental and model structures of WO x , a dimension of structural elements in the model should coincide with W-O cluster size.

  11. Stress relaxation and hillock growth in thin films

    International Nuclear Information System (INIS)

    Jackson, M.S.; Li, C.Y.

    1978-01-01

    The relaxation of thermal stress in a thin film adhering to a substrate of differing expansion coefficient is discussed. Good agreement is found between literature data on relaxation during isothermal anneals of Pb films at up to 350 0 K and model calculations based on a state variable description of plastic flow. The stress system during relaxation is explored, and the absence of diffusional creep is explained. The plasticity-dominated relaxation process suggested by this analysis is shown to be in good qualitative agreement with data on rapid relaxation over the course of a cycle between room and cryogenic temperatures. The implications of this for long-range material transport in the film are discussed. It is shown that hillock volume should increase over the course of a temperature cycle. Finally, a mechanism for hillock nucleation based on grain boundary sliding is suggested

  12. [Spectroscopic study on film formation mechanism and structure of composite silanes-V-Zr passive film].

    Science.gov (United States)

    Wang, Lei; Liu, Chang-sheng; Shi, Lei; An, Cheng-qiang

    2015-02-01

    A composite silanes-V-Zr passive film was overlayed on hot-dip galvanized steel. Attenuated total reflection Fourier transformed infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectrometer (XPS) and radio frequency glow discharge optical emission spectrometry (rf-GD-OES) were used to characterize the molecular structure of the silanes-V-Zr passive film. The mechanism of film formation was discussed: The results show that the silane molecules are crosslinked as the main film former and inorganic inhibitor is even distributed in the film. The fitting peak of 100.7 eV in XPS single Si2p energy range spectra of the composite silanes-V-Zr passive film and the widening and strengthening of the Si--O infrared absorption peak at 1100 cm(-1) indicate that the silanes were adsorbed on the surface of zinc with chemical bond of Si--O--Zn, and the silane molecules were connected with each other by bond of Si--O--Si. Two characteristic absorption peaks of amide at 1650 and 1560 cm(-1) appear in the infrared spectroscopy of the composite silanes-V-Zr passive film, and a characteristic absorption peak of epoxy groups at 910 cm(-1) disappears in the infrared spectroscopy of the passive film. The results indicate that gamma-APT can be prepared through nucleophilic ring-opening of ethylene oxide in gamma-GPT molecule to form C--N covalent bonds. The rf-GD-OES results indicate that there is a oxygen enriched layer in 0.3 microm depth of the composite silanes-V-Zr passive film. Moreover, ZrF4, ZrO2 and some inorganic matter obtained by the reaction during the forming processof the composite silanes-V-Zr passive film are distributed evenly throughout the film. According to the film composition, the physical processes and chemical reactions during the film forming process were studied by using ATR-FTIR. Based on this, the film forming mechanism was proposed.

  13. Growth of mirror-like ultra-nanocrystalline diamond (UNCD) films by a facile hybrid CVD approach

    Science.gov (United States)

    Yang, Shuo; Man, Weidong; Lyu, Jilei; Xiao, Xiong; You, Zhiheng; Jiang, Nan

    2017-05-01

    In this study, growth of mirror-like ultra-nanocrystalline diamond (UNCD) films by a facile hybrid CVD approach was presented. The nucleation and deposition of UNCD films were conducted in microwave plasma CVD (MPCVD) and direct current glow discharge CVD (DC GD CVD) on silicon substrates, respectively. A very high nucleation density (about 1 × 1011 nuclei cm-2) was obtained after plasma pretreatment. Furthermore, large area mirror-like UNCD films of Φ 50 mm were synthesized by DC GD CVD. The thickness and grain size of the UNCD films are 24 μm and 7.1 nm, respectively. In addition, the deposition mechanism of the UNCD films was discussed. Development of CVD ultra-nanocrystalline diamond films and related high-precision machining products (International S&T Cooperation, No. S2015ZR1100).

  14. Correlation between substrate bias, growth process and structural properties of phosphorus incorporated tetrahedral amorphous carbon films

    International Nuclear Information System (INIS)

    Liu Aiping; Zhu Jiaqi; Han Jiecai; Wu Huaping; Jia Zechun

    2007-01-01

    We investigate the growth process and structural properties of phosphorus incorporated tetrahedral amorphous carbon (ta-C:P) films which are deposited at different substrate biases by filtered cathodic vacuum arc technique with PH 3 as the dopant source. The films are characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy, Raman spectroscopy, residual stress measurement, UV/VIS/NIR absorption spectroscopy and temperature-dependent conductivity measurement. The atomic fraction of phosphorus in the films as a function of substrate bias is obtained by XPS analysis. The optimum bias for phosphorus incorporation is about -80 V. Raman spectra show that the amorphous structures of all samples with atomic-scaled smooth surface are not remarkably changed when PH 3 is implanted, but some small graphitic crystallites are formed. Moreover, phosphorus impurities and higher-energetic impinging ions are favorable for the clustering of sp 2 sites dispersed in sp 3 skeleton and increase the level of structural ordering for ta-C:P films, which further releases the compressive stress and enhances the conductivity of the films. Our analysis establishes an interrelationship between microstructure, stress state, electrical properties, and substrate bias, which helps to understand the deposition mechanism of ta-C:P films

  15. Effect of Substrate Morphology on Growth and Field Emission Properties of Carbon Nanotube Films

    Directory of Open Access Journals (Sweden)

    Kumar Vikram

    2008-01-01

    Full Text Available AbstractCarbon nanotube (CNT films were grown by microwave plasma-enhanced chemical vapor deposition process on four types of Si substrates: (i mirror polished, (ii catalyst patterned, (iii mechanically polished having pits of varying size and shape, and (iv electrochemically etched. Iron thin film was used as catalytic material and acetylene and ammonia as the precursors. Morphological and structural characteristics of the films were investigated by scanning and transmission electron microscopes, respectively. CNT films of different morphology such as vertically aligned, randomly oriented flowers, or honey-comb like, depending on the morphology of the Si substrates, were obtained. CNTs had sharp tip and bamboo-like internal structure irrespective of growth morphology of the films. Comparative field emission measurements showed that patterned CNT films and that with randomly oriented morphology had superior emission characteristics with threshold field as low as ~2.0 V/μm. The defective (bamboo-structure structures of CNTs have been suggested for the enhanced emission performance of randomly oriented nanotube samples.

  16. Growth kinetics and characterizations of gallium nitride thin films by remote PECVD

    Science.gov (United States)

    Choi, S. W.; Bachmann, K. J.; Lucovsky, G.

    1993-01-01

    Thin films of GaN have been deposited at relatively low growth temperatures by remote plasma-enhanced chemical-vapor deposition (RPECVD), using a plasma excited NH3, and trimethylgallium (TMG), injected downstream from the plasma. The activation energy for GaN growth has been tentatively assigned to the dissociation of NH groups as the primary N-atom precursors in the surface reaction with adsorbed TMG, or TMG fragments. At high He flow rates, an abrupt increase in the growth rate is observed and corresponds to a change in the reaction mechanism attributed to the formation of atomic N. XRD reveals an increased tendency to ordered growth in the (0001) direction with increasing growth temperature, He flow rate, and RF plasma power. IR spectra show the fundamental lattice mode of GaN at 530 cm without evidence for vibrational modes of hydrocarbon groups.

  17. Ultra-thin film encapsulation processes for micro-electro-mechanical devices and systems

    International Nuclear Information System (INIS)

    Stoldt, Conrad R; Bright, Victor M

    2006-01-01

    A range of physical properties can be achieved in micro-electro-mechanical systems (MEMS) through their encapsulation with solid-state, ultra-thin coatings. This paper reviews the application of single source chemical vapour deposition and atomic layer deposition (ALD) in the growth of submicron films on polycrystalline silicon microstructures for the improvement of microscale reliability and performance. In particular, microstructure encapsulation with silicon carbide, tungsten, alumina and alumina-zinc oxide alloy ultra-thin films is highlighted, and the mechanical, electrical, tribological and chemical impact of these overlayers is detailed. The potential use of solid-state, ultra-thin coatings in commercial microsystems is explored using radio frequency MEMS as a case study for the ALD alloy alumina-zinc oxide thin film. (topical review)

  18. Numerical Simulation of Vapor Bubble Growth and Heat Transfer in a Thin Liquid Film

    International Nuclear Information System (INIS)

    Yu-Jia, Tao; Xiu-Lan, Huai; Zhi-Gang, Li

    2009-01-01

    A mathematical model is developed to investigate the dynamics of vapor bubble growth in a thin liquid film, movement of the interface between two fluids and the surface heat transfer characteristics. The model takes into account the effects of phase change between the vapor and liquid, gravity, surface tension and viscosity. The details of the multiphase now and heat transfer are discussed for two cases: (1) when a water micro-droplet impacts a thin liquid film with a vapor bubble growing and (2) when the vapor bubble grows and merges with the vapor layer above the liquid film without the droplet impacting. The development trend of the interface between the vapor and liquid is coincident qualitatively with the available literature, mostly at the first stage. We also provide an important method to better understand the mechanism of nucleate spray cooling. (fundamental areas of phenomenology (including applications))

  19. Modified Starch-Chitosan Edible Films: Physicochemical and Mechanical Characterization

    Directory of Open Access Journals (Sweden)

    Monserrat Escamilla-García

    2017-12-01

    Full Text Available Starch and chitosan are widely used for preparation of edible films that are of great interest in food preservation. This work was aimed to analyze the relationship between structural and physical properties of edible films based on a mixture of chitosan and modified starches. In addition, films were tested for antimicrobial activity against Listeria innocua. Films were prepared by the casting method using chitosan (CT, waxy (WS, oxidized (OS and acetylated (AS corn starches and their mixtures. The CT-starches films showed improved barrier and mechanical properties as compared with those made from individual components, CT-OS film presented the lowest thickness (74 ± 7 µm, water content (11.53% ± 0.85%, w/w, solubility (26.77% ± 1.40%, w/v and water vapor permeability ((1.18 ± 0.48 × 10−9 g·s−1·m−1·Pa−1. This film showed low hardness (2.30 ± 0.19 MPa, low surface roughness (Rq = 3.20 ± 0.41 nm and was the most elastic (Young’s modulus = 0.11 ± 0.06 GPa. In addition, films made from CT-starches mixtures reduced CT antimicrobial activity against L. innocua, depending on the type of modified starch. This was attributed to interactions between acetyl groups of AS with the carbonyl and amino groups of CT, leaving CT with less positive charge. Interaction of the pyranose ring of OS with CT led to increased OH groups that upon interaction with amino groups, decreased the positive charge of CT, and this effect is responsible for the reduced antimicrobial activity. It was found that the type of starch modification influenced interactions with chitosan, leading to different films properties.

  20. Contact mechanics studies of polymer thin film adhesion

    Science.gov (United States)

    McSwain, Rachel Lynn

    The work presented in this dissertation focuses on using the unique abilities of the JKR technique to probe the interfacial interactions of two independent polymer systems. To perform these studies, modifications were made to the JKR technique, including the integration of a thermal cycle to enable testing of thermally initiated interfacial interactions between two materials. Another enhancement of the JKR technique involved incorporation of cyclic testing to study crack growth under fatigue conditions. These additions to the JKR technique were used in the analysis of interfacial interactions of poly(tetramethyl bisphenol-A polycarbonate) (TMPC) and poly(ethylene oxide) (PEO). Adhesion tests were performed on thin layers of PEO sandwiched between layers of TMPC, which were heated in contact above the melting temperature of the PEO and cooled back to room temperature before a cyclic fatigue test was performed. Additional characterization of the bulk and interfacial properties of this blend showed that these two polymers are miscible. From these studies, the interfacial interaction of the TMPC and PEO was found to be controlled by the PEO-mediated mixing of the TMPC layers. In a second set of experiments, a model film consisting of a layer of acrylic diblock copolymer micelles was used to study the processes involved in the transfer of a viscoelastic film from a weakly adhesive elastomer substrate to a more strongly adhesive hemispherical glass indenter. Transfer of the film during tensile loading of the indenter began with expansion of a cavity at the film/elastomer interface, followed by subsequent delamination of the film at this interface. Criteria for cavity expansion and delamination are expressed in terms of the energy release rate. The critical energy release rate for cavity expansion increases linearly with the film thickness. A critical film thickness was identified above which films are able to peel from the elastomeric substrate over a region outside the

  1. Mechanical and microstructure studies on the modification of CA film ...

    Indian Academy of Sciences (India)

    The films of these composites or their individual partners were made separately and studied for their mechanical properties, chemical modification and morphological changes. We report here that banana stem is good source of cellulose and that cellulose completely undergoes modification upon esterification.

  2. Thermal and dynamic mechanical properties of hydroxypropyl cellulose films

    Science.gov (United States)

    Timothy G. Rials; Wolfgang G. Glasser

    1988-01-01

    Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) were used to characterize the morphology of slovent cast hydroxypropyl cellulose (HPC) films. DSC results were indicative of a semicrystalline material with a melt of 220°C and a glass transition at 19°C (T1), although an additional event was suggested by a...

  3. Mechanical Robustness and Hermeticity Monitoring for MEMS Thin Film Encapsulation

    NARCIS (Netherlands)

    Santagata, F.

    2011-01-01

    Many Micro-Electro-Mechanical-Systems (MEMS) require encapsulation, to prevent delicate sensor structures being exposed to external perturbations such as dust, humidity, touching, and gas pressure. An upcoming and cost-effective way of encapsulation is zero-level packaging or thin-film

  4. Buckyball microwave plasmas: Fragmentation and diamond-film growth

    International Nuclear Information System (INIS)

    Gruen, D.M.; Liu, Shengzhong; Krauss, A.R.; Pan, Xianzheng.

    1993-08-01

    Microwave discharges (2.45 GHz) have been generated in C 60 -containing Ar produced by flowing Ar over fullerene-containing soot. Optical spectroscopy shows that the spectrum is dominated by the d 3 Πg-a 3 Πu Swan bands of C 2 and particularly the Δv = -2, -1, 0, +1, and +2 sequences. These results give direct evidence that C 2 is one of the products of C 60 fragmentation brought about, at least in part, by collisionally induced dissociation (CID). C 60 has been used as a precursor in a plasma-enhanced chemical vapor deposition (PECVD) experiment to grow diamond-thin films. The films, grown in an Ar/H 2 gas mixture (0.14% carbon content, 100 Torr, 20 sccm Ar, 4 sccm H 2 , 1500 W, 850 degree C substrate temperature), were characterized with SEM, XRD, and Raman spectroscopy. Growth rate was found to be ∼ 0.6 μ/hr. Assuming a linear dependence on carbon concentration, a growth rate at least six times higher than commonly observed using methane as a precursor, would be predicted at a carbon content of 1% based on C 60 . Energetic and mechanistic arguments are advanced to rationalize this result based on C 2 as the growth species

  5. GaSb film growth by liquid phase epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Cruz, M.L.; Martinez-Juarez, J.; Lopez-Salazar, P. [CIDS-ICUAP, BUAP, Av. 14 Sur y San Claudio, C.U. Edif.103C, Col. Sn Manuel, C.P. 72570, Puebla, Pue. (Mexico); Diaz, G.J. [Centro de Investigacion y Estudios Avanzados, IPN, Av. IPN 2508, Col. Sn. Pedro Zacatenco, C.P. 07360, D.F. (Mexico)

    2010-04-15

    Doped GaSb (Gallium Antimonide) films on p-GaSb substrates have been obtained by means of a low-cost and fast-growth method: the liquid phase epitaxy (LPE) technique. The growth temperature was 400 C, and the growth time was varied between1 and 5 min. Characterization of the films was performed by means of high resolution X-ray Diffraction, low temperature-photoluminescence and current-voltage curve measurements. The X-ray diffraction pattern confirms a zincblende-type crystal structure with a high-thin peak centred at 30.36 . The PL spectra at 27 K allowed to confirm the band-gap energy to be 0.8 eV and the I-V curves presented a PN junction behavior which corresponds to the obtained structured. Metal contacts of Au-Zn and Au-Ge were placed to perform electrical characterization (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Nano mechanical properties of carbon films modified by ion radiation

    International Nuclear Information System (INIS)

    Foerster, C.E.; Serbena, F.C.; Lepienski, C.M.; Odo, G.Y.; Zawislak, F.C.; Lopes, J.M.J.; Baptista, D.L.; Garcia, I.T.S.

    2000-01-01

    In present work it is measured hardness, Young modulus and friction coefficient values for different types of carbon films. These films were submitted to different ion bombardment conditions (energy and fluencies). The mechanical behavior was obtained by nano indentation technique and analyzed by the Oliver/Pharr method. For friction coefficient determination the nano scratch procedure is used. Pristine C 60 films (fullerenes) has a hardness of 0.33 GPa. After irradiation with different ions (He, N and Bi), the hardness raise to about 14 GPa and the Young modulus change from 20 to about 200 GPa. For photoresist film AZ-1350J irradiation with Ar and He change the hardness from 0.4 to about 14 GPa and the Young modulus raise from 4 to 80 GPa. In a-C-H the hardness change from 3.5 to 11 GPa when submitted to N irradiation. In PPA films the hardness value raise from 0.5 to 11 GPa after irradiation with Ar. These mechanical and tribological results were analyzed in terms of deposited energy by the ion irradiation and compared with those presented in the literature. (author)

  7. Barrier, mechanical and optical properties of whey protein concentrate films

    Directory of Open Access Journals (Sweden)

    Viviane Machado Azevedo

    2014-08-01

    Full Text Available Whey is recognized as a valuable source of high quality protein and, when processed as protein concentrate, may be used in the production of biodegradable films. The objective of the study was to develop films of whey protein concentrate 80% (WPC at concentrations of 6, 8, 10 and 12% and evaluate the influence of this factor in the barrier, mechanical and optical properties of the films. Treatments showed moisture content with a mean value of 22.10% ± 0.76and high solubility values between 56.67 to 62.42%. Thus, there is little or no influence of varying the concentration of WPC in these properties and high hydrophilicity of the films. With increasing concentration of WPC, increases the water vapor permeability of the films (7.42 x 10-13 to 3.49 x 10-12 g.m-1.s-1.Pa-1. The treatment at the concentration of 6% of WPC showed a higher modulus of elasticity (287.90 ± 41.79 MPa. Thegreater rigidity in films with higher concentrations is possibly due to the greater number of bonds between molecules of the polymeric matrix. The films have the same puncture resistance. The increased concentration of WPC promotes resistance to the action of a localized force. In general, films of whey protein concentrate in the tested concentrations exhibited slightly yellowish color and transparency, and can be used in food packaging that requiring intermediate permeability to water vapor, to keep moisture and texture desired.

  8. Growth of HfN thin films by reactive high power impulse magnetron sputtering

    Directory of Open Access Journals (Sweden)

    D. Ö. Thorsteinsson

    2018-03-01

    Full Text Available Thin hafnium nitride films were grown on SiO2 by reactive high power impulse magnetron sputtering (HiPIMS and reactive direct current magnetron sputtering (dcMS. The conditions during growth were kept similar and the film properties were compared as growth temperature, nitrogen flow rate, and in the case of HiPIMS, duty cycle were independently varied. The films were characterized with grazing incidence X-ray diffraction (GIXRD, X-ray reflection (XRR and X-ray stress analysis (XSA. HiPIMS growth had a lower growth rate for all grown films, but the films surfaces were smoother. The film density of HiPIMS deposited films grown at low duty cycle was comparable to dcMS grown films. Increasing the duty cycle increased the density of the HiPIMS grown films almost to the bulk density of HfN as well as increasing the growth rate, while the surface roughness did not change significantly. The HiPIMS grown films had large compressive stress while the dcMS grown films had some tensile stress. The dcMS grown films exhibit larger grains than HiPIMS grown films. The grain size of HiPIMS grown films decreases with increasing nitrogen flow rate, while the dcMS grain size increased with increasing nitrogen flow rate. This work shows that duty cycle during HiPIMS growth of HfN films has a significant effect on the film density and growth rate while other film properties seem mostly unaffected.

  9. Antimicrobial, Optical and Mechanical Properties of Chitosan–Starch Films with Natural Extracts

    Science.gov (United States)

    Lozano-Navarro, Jessica I.; Díaz-Zavala, Nancy P.; Velasco-Santos, Carlos; Martínez-Hernández, Ana L.; Tijerina-Ramos, Beatriz I.; García-Hernández, Margarita; Rivera-Armenta, José L.; Páramo-García, Ulises; Reyes-de la Torre, Adriana I.

    2017-01-01

    Natural extracts possess several kinds of antioxidants (anthocyanins, betalains, thymol, carvacrol, and resveratrol) that have also demonstrated antimicrobial properties. In order to study these properties, extracts from cranberry, blueberry, beetroot, pomegranate, oregano, pitaya, and resveratrol (from grapes) were obtained. Growth inhibition tests of mesophilic aerobes, coliforms, and fungi were conducted in films prepared from the extracts in accordance with Mexican Official Norms (NOM). Optical properties such as transparency and opacity, mechanical properties, and pH were also analyzed in these materials. The films with beetroot, cranberry, and blueberry extracts demonstrated the best antimicrobial activity against various bacteria and fungi in comparison with unmodified chitosan–starch film. This study shows that the addition of antioxidants improved the antimicrobial performance of these films. It was also found that antimicrobial properties are inherent to the films. These polymers combined with the extracts effectively inhibit or reduce microorganism growth from human and environmental contact; therefore, previous sterilization could be unnecessary in comparison with traditional plastics. The presence of extracts decreased transmittance percentages at 280 and 400 nm, as well as the transparency values, while increasing their opacity values, providing better UV–VIS light barrier properties. Despite diminished glass transition temperatures (Tg), the values obtained are still adequate for food packaging applications. PMID:28475151

  10. Antimicrobial, Optical and Mechanical Properties of Chitosan-Starch Films with Natural Extracts.

    Science.gov (United States)

    Lozano-Navarro, Jessica I; Díaz-Zavala, Nancy P; Velasco-Santos, Carlos; Martínez-Hernández, Ana L; Tijerina-Ramos, Beatriz I; García-Hernández, Margarita; Rivera-Armenta, José L; Páramo-García, Ulises; Reyes-de la Torre, Adriana I

    2017-05-05

    Natural extracts possess several kinds of antioxidants (anthocyanins, betalains, thymol, carvacrol, and resveratrol) that have also demonstrated antimicrobial properties. In order to study these properties, extracts from cranberry, blueberry, beetroot, pomegranate, oregano, pitaya, and resveratrol (from grapes) were obtained. Growth inhibition tests of mesophilic aerobes, coliforms, and fungi were conducted in films prepared from the extracts in accordance with Mexican Official Norms (NOM). Optical properties such as transparency and opacity, mechanical properties, and pH were also analyzed in these materials. The films with beetroot, cranberry, and blueberry extracts demonstrated the best antimicrobial activity against various bacteria and fungi in comparison with unmodified chitosan-starch film. This study shows that the addition of antioxidants improved the antimicrobial performance of these films. It was also found that antimicrobial properties are inherent to the films. These polymers combined with the extracts effectively inhibit or reduce microorganism growth from human and environmental contact; therefore, previous sterilization could be unnecessary in comparison with traditional plastics. The presence of extracts decreased transmittance percentages at 280 and 400 nm, as well as the transparency values, while increasing their opacity values, providing better UV-VIS light barrier properties. Despite diminished glass transition temperatures ( T g), the values obtained are still adequate for food packaging applications.

  11. Growth of carbon fibres, sheets and tubes on diamond films under high power plasma etching conditions

    International Nuclear Information System (INIS)

    Villalpando, I.; John, P.; Wilson, J. I. B.

    2017-01-01

    The application of diamond as a plasma facing material for fusion reactors can be limited by unknown reactions between diamond and the chamber materials transported by the plasma. Transformation of diamond to other structures can cause problems such as contamination of the plasma with loose particles or retention of gases. We have seen that diamond thin films are eroded under hydrogen plasma etching, but if silicon is present the growth of various carbon structures on diamond films is observed. We have produced carbon with different morphologies on diamond films including fibres, sheets with flower-like shapes and tubes and proposed growth mechanisms based on the results of scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Sample surfaces contain silicon and are oxidised having COO and CO groups as seen by XP S analysis. Raman analyses revealed a spectrum typical for graphite combined with that from diamond that remains on the surface after hydrogen bombardment. The results of this sturdy show the experimental conditions in which carbon fibres, sheets and tubes are produced under high-power hydrogen etching of diamond films and open the possibility to other applications such as catalysts, sensors and the production of electrodes. (Author)

  12. Growth of carbon fibres, sheets and tubes on diamond films under high power plasma etching conditions

    Energy Technology Data Exchange (ETDEWEB)

    Villalpando, I. [Centro de Investigacion de los Recursos Naturales, Antigua Normal Rural, Salaices, Lopez, Chihuahua (Mexico); John, P.; Wilson, J. I. B., E-mail: isaelav@hotmail.com [School of Engineering and Physical Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14-4AS (United Kingdom)

    2017-11-01

    The application of diamond as a plasma facing material for fusion reactors can be limited by unknown reactions between diamond and the chamber materials transported by the plasma. Transformation of diamond to other structures can cause problems such as contamination of the plasma with loose particles or retention of gases. We have seen that diamond thin films are eroded under hydrogen plasma etching, but if silicon is present the growth of various carbon structures on diamond films is observed. We have produced carbon with different morphologies on diamond films including fibres, sheets with flower-like shapes and tubes and proposed growth mechanisms based on the results of scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Sample surfaces contain silicon and are oxidised having COO and CO groups as seen by XP S analysis. Raman analyses revealed a spectrum typical for graphite combined with that from diamond that remains on the surface after hydrogen bombardment. The results of this sturdy show the experimental conditions in which carbon fibres, sheets and tubes are produced under high-power hydrogen etching of diamond films and open the possibility to other applications such as catalysts, sensors and the production of electrodes. (Author)

  13. Growth of high quality AlN films on CVD diamond by RF reactive magnetron sputtering

    Science.gov (United States)

    Chen, Liang-xian; Liu, Hao; Liu, Sheng; Li, Cheng-ming; Wang, Yi-chao; An, Kang; Hua, Chen-yi; Liu, Jin-long; Wei, Jun-jun; Hei, Li-fu; Lv, Fan-xiu

    2018-02-01

    A highly oriented AlN layer has been successfully grown along the c-axis on a polycrystalline chemical vapor deposited (CVD) diamond by RF reactive magnetron sputtering. Structural, morphological and mechanical properties of the heterostructure were investigated by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Nano-indentation and Four-probe meter. A compact AlN film was demonstrated on the diamond layer, showing columnar grains and a low surface roughness of 1.4 nm. TEM results revealed a sharp AlN/diamond interface, which was characterized by the presence of a distinct 10 nm thick buffer layer resulting from the initial AlN growth stage. The FWHM of AlN (002) diffraction peak and its rocking curve are as low as 0.41° and 3.35° respectively, indicating a highly preferred orientation along the c-axis. AlN sputtered films deposited on glass substrates show a higher bulk resistivity (up to 3 × 1012 Ω cm), compared to AlN films deposited on diamond (∼1010 Ω cm). Finally, the film hardness and Young's modulus of AlN films on diamond are 25.8 GPa and 489.5 GPa, respectively.

  14. Thin Film Composite Membranes: Mechanical and Antifouling Properties

    Directory of Open Access Journals (Sweden)

    Kassim Shaari Norin Zamiah

    2017-01-01

    Full Text Available As compared to membranes produced from pure polymer or pure inorganic materials, a hybrid membrane possesses better mechanical and thermal properties. This paper reported on the effect of incorporating silica nano-precursor (tetraethylorthosilicate as well as glycerol in the formulation of hybrid membrane on the mechanical properties and antifouling properties of the resultant thin film composite membranes. The mechanical properties were measured in terms of tensile strength, tensile strain and elastic modulus. Whereas for antifouling properties, it was evaluated through the measurements of relative flux decay (RFD and relative flux recovery (RFR, along with the permeate flux rate, percentage glycerol permeated and NaCl rejection. Results showed that the presence of silica and glycerol in hybrid membrane’s formulation had increased the tensile strength and elongation of the resultant membranes. In addition to that, the incorporation of glycerol has resulted in thin film composite with better antifouling properties as compared to the thin film composite with barrier layer from the pure polymer blend. Based on its performance, the fabricated thin film composite has a great potential to be used as a pathway for crude glycerol purification due to some advantages over the existing process that employ membrane.

  15. A nonlinear model for surface segregation and solute trapping during planar film growth

    International Nuclear Information System (INIS)

    Han, Xiaoying; Spencer, Brian J.

    2007-01-01

    Surface segregation and solute trapping during planar film growth is one of the important issues in molecular beam epitaxy, yet the study on surface composition has been largely restricted to experimental work. This paper introduces some mathematical models of surface composition during planar film growth. Analytical solutions are obtained for the surface composition during growth

  16. Existence of thickness threshold for crystal growth rate of ascorbic acid from its thin solution film

    Science.gov (United States)

    Yamazaki, Yoshihiro; Yoshino, Hiroki; Kikuchi, Mitsunobu; Kashiwase, Sakiko

    2017-06-01

    Growth rate of ascorbic acid crystal domains from its aqueous solution film depends on the film thickness. Existence of a thickness threshold is experimentally confirmed below which growth rate becomes quite low and is considered to almost stop. This threshold is one of the essential factors for the dynamical transition between uniform and rhythmic growth modes.

  17. Epitaxial growth of fcc-CoxNi100-x thin films on MgO(110) single-crystal substrates

    International Nuclear Information System (INIS)

    Ohtake, Mitsuru; Nukaga, Yuri; Sato, Yoichi; Futamoto, Masaaki; Kirino, Fumiyoshi

    2009-01-01

    Co x Ni 100-x (x=100, 80, 20, 0 at. %) epitaxial thin films were prepared on MgO(110) single-crystal substrates heated at 300 deg. C by ultrahigh vacuum molecular beam epitaxy. The growth mechanism is discussed based on lattice strain and crystallographic defects. CoNi(110) single-crystal films with a fcc structure are obtained for all compositions. Co x Ni 100-x film growth follows the Volmer-Weber mode. X-ray diffraction analysis indicates that the out-of-plane and the in-plane lattice spacings of the Co x Ni 100-x films are in agreement within ±0.5% with the values of the respective bulk Co x Ni 100-x crystals, suggesting that the strain in the film is very small. High-resolution cross-sectional transmission microscopy shows that an atomically sharp boundary is formed between a Co(110) fcc film and a MgO(110) substrate, where periodical misfit dislocations are preferentially introduced in the film at the Co/MgO interface. The presence of such periodical misfit dislocations relieves the strain caused by the lattice mismatch between the film and the substrate.

  18. Formation mechanism of ordered stress-relief patterns in a free sustained Cu film system

    International Nuclear Information System (INIS)

    Chen Miaogen; Xie Jianping; Jin Jinsheng; Xia Agen; Yu Gaoxiang

    2008-01-01

    A nearly free sustained copper (Cu) film system has been successfully fabricated by thermal evaporation deposition of Cu atoms on silicone oil surfaces, and a characteristic ordered pattern has been systematically studied. The ordered pattern, namely, band, is composed of a large number of parallel key-formed domains with different width w but nearly uniform length L; its characteristic values of w and L are very susceptible to the growth period, deposition rate and nominal film thickness. The formation mechanism of the ordered patterns is well explained in terms of the relaxation of the internal stress in the films, which is related to the nearly zero adhesion of the solid-liquid interface. By using a two-time deposition method, it is confirmed that the ordered patterns really form in the vacuum chamber

  19. Mechanical properties of molybdenum coated with titanium carbide film

    International Nuclear Information System (INIS)

    Shikama, T.; Shinno, H.; Fukutomi, M.; Fujitsuka, M.; Okada, M.

    1983-01-01

    TiC-coated molybdenum is mechanically tensile tested. The 6 μm thick TiC-coated molybdenum has a higher 0.2% proof strength with a slight decrease in uniform and rupture elongation than the uncoated one. This strengthening effect of the TiC coating can be explained by the constrained effect of the high strength TiC film. The 1.2 μm thick TiC-coated molybdenum starts its plastic deformation at a lower stress than the uncoated one. Also, the coating makes the stress-strain curve more smooth. These effects are attributed to the surface effect, namely, that the interface between the molybdenum substrate and the strong and brittle TiC film acts as a strong dislocation source. The compressive stress in the TiC film will also help the start of plastic deformation at lower external stresses. (author)

  20. Microstructure and mechanical properties of stress-tailored piezoelectric AlN thin films for electro-acoustic devices

    Energy Technology Data Exchange (ETDEWEB)

    Reusch, Markus, E-mail: markus.reusch@iaf.fraunhofer.de [Laboratory for Compound Semiconductor Microsystems, IMTEK - Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg (Germany); Fraunhofer Institute for Applied Solid State Physics, Tullastrasse 72, 79108 Freiburg (Germany); Cherneva, Sabina [Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 4, 1113 Sofia (Bulgaria); Lu, Yuan; Žukauskaitė, Agnė; Kirste, Lutz; Holc, Katarzyna [Fraunhofer Institute for Applied Solid State Physics, Tullastrasse 72, 79108 Freiburg (Germany); Datcheva, Maria [Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 4, 1113 Sofia (Bulgaria); Stoychev, Dimitar [Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia (Bulgaria); Lebedev, Vadim [Fraunhofer Institute for Applied Solid State Physics, Tullastrasse 72, 79108 Freiburg (Germany); Ambacher, Oliver [Laboratory for Compound Semiconductor Microsystems, IMTEK - Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg (Germany); Fraunhofer Institute for Applied Solid State Physics, Tullastrasse 72, 79108 Freiburg (Germany)

    2017-06-15

    Highlights: • Sputtered AlN thin films with minimized intrinsic stress gradient. • Gradual increase of N{sub 2} concentration during film growth. • No degradation of AlN film properties by changing process conditions. • 2D Raman mapping of nanoindentation area. - Abstract: Nanoindentation measurements along with atomic force microscopy, X-ray diffraction, and residual stress analyses on the basis of Raman measurements have been performed to characterize stress-tailored AlN thin films grown using reactive RF magnetron sputtering. The intrinsic stress gradient caused by the growing in-plane grain size along film thickness was minimized by increasing the N{sub 2} concentration in the Ar/N{sub 2} gas mixture during the growth process. The increase of N{sub 2} concentration did not degrade the device-relevant material properties such as crystallographic orientation, surface morphology, piezoelectric response, or indentation modulus. Due to comparable crystallographic film properties for all investigated samples it was concluded that mainly the AlN crystallites contribute to the mechanical film properties such as indentation modulus and hardness, while the film stress or grain boundaries had only a minor influence. Therefore, by tailoring the stress gradient in the AlN films, device performance, fabrication yield, and the design flexibility of electro-acoustic devices can be greatly improved.

  1. Effect of interface layer on growth behavior of atomic-layer-deposited Ir thin film as novel Cu diffusion barrier

    International Nuclear Information System (INIS)

    Choi, Bum Ho; Lee, Jong Ho; Lee, Hong Kee; Kim, Joo Hyung

    2011-01-01

    Growth and nucleation behavior of Ir films grown by atomic layer deposition (ALD) on different interfacial layers such as SiO 2 , surface-treated TaN, and 3-nm-thick TaN were investigated. To grow Ir thin film by ALD, (1,5-cyclooctadiene) (ethylcyclopentadienyl) iridium (Ir(EtCp)(COD)) and oxygen were employed as the metalorganic precursor and reactant, respectively. To obtain optimal deposition conditions, the deposition temperature was varied from 240 to 420 deg. C and the number of deposition cycles was changed from 150 to 300. The Ir film grown on the 3-nm-thick TaN surface showed the smoothest and most uniform layer for all the deposition cycles, whereas poor nucleation and three-dimensional island-type growth of the Ir layer were observed on Si, SiO 2 , and surface-treated TaN after fewer number of deposition cycles. The uniformity of the Ir film layer was maintained for all the different substrates up to 300 deposition cycles. Therefore we suggest that the growth behavior of the Ir layer on different interface layer is related to the chemical bonding pattern of the substrate film or interface layer, resulting in better understand the growth mechanism of Ir layer as a copper diffusion barrier. The ALD-grown Ir films show the preferential direction of (1 1 1) for all the reflections, which indicates the absence of IrO 2 in metallic Ir.

  2. Piezoresistivity of mechanically drawn single-walled carbon nanotube (SWCNT) thin films-: mechanism and optimizing principle

    Science.gov (United States)

    Obitayo, Waris

    The individual carbon nanotube (CNT) based strain sensors have been found to have excellent piezoresistive properties with a reported gauge factor (GF) of up to 3000. This GF on the other hand, has been shown to be structurally dependent on the nanotubes. In contrast, to individual CNT based strain sensors, the ensemble CNT based strain sensors have very low GFs e.g. for a single walled carbon nanotube (SWCNT) thin film strain sensor, GF is ~1. As a result, studies which are mostly numerical/analytical have revealed the dependence of piezoresistivity on key parameters like concentration, orientation, length and diameter, aspect ratio, energy barrier height and Poisson ratio of polymer matrix. The fundamental understanding of the piezoresistive mechanism in an ensemble CNT based strain sensor still remains unclear, largely due to discrepancies in the outcomes of these numerical studies. Besides, there have been little or no experimental confirmation of these studies. The goal of my PhD is to study the mechanism and the optimizing principle of a SWCNT thin film strain sensor and provide experimental validation of the numerical/analytical investigations. The dependence of the piezoresistivity on key parameters like orientation, network density, bundle diameter (effective tunneling area), and length is studied, and how one can effectively optimize the piezoresistive behavior of a SWCNT thin film strain sensors. To reach this goal, my first research accomplishment involves the study of orientation of SWCNTs and its effect on the piezoresistivity of mechanically drawn SWCNT thin film based piezoresistive sensors. Using polarized Raman spectroscopy analysis and coupled electrical-mechanical test, a quantitative relationship between the strain sensitivity and SWCNT alignment order parameter was established. As compared to randomly oriented SWCNT thin films, the one with draw ratio of 3.2 exhibited ~6x increase on the GF. My second accomplishment involves studying the

  3. Practice-oriented optical thin film growth simulation via multiple scale approach

    Energy Technology Data Exchange (ETDEWEB)

    Turowski, Marcus, E-mail: m.turowski@lzh.de [Laser Zentrum Hannover e.V., Hollerithallee 8, Hannover 30419 (Germany); Jupé, Marco [Laser Zentrum Hannover e.V., Hollerithallee 8, Hannover 30419 (Germany); QUEST: Centre of Quantum Engineering and Space-Time Research, Leibniz Universität Hannover (Germany); Melzig, Thomas [Fraunhofer Institute for Surface Engineering and Thin Films IST, Bienroder Weg 54e, Braunschweig 30108 (Germany); Moskovkin, Pavel [Research Centre for Physics of Matter and Radiation (PMR-LARN), University of Namur (FUNDP), 61 rue de Bruxelles, Namur 5000 (Belgium); Daniel, Alain [Centre for Research in Metallurgy, CRM, 21 Avenue du bois Saint Jean, Liège 4000 (Belgium); Pflug, Andreas [Fraunhofer Institute for Surface Engineering and Thin Films IST, Bienroder Weg 54e, Braunschweig 30108 (Germany); Lucas, Stéphane [Research Centre for Physics of Matter and Radiation (PMR-LARN), University of Namur (FUNDP), 61 rue de Bruxelles, Namur 5000 (Belgium); Ristau, Detlev [Laser Zentrum Hannover e.V., Hollerithallee 8, Hannover 30419 (Germany); QUEST: Centre of Quantum Engineering and Space-Time Research, Leibniz Universität Hannover (Germany)

    2015-10-01

    Simulation of the coating process is a very promising approach for the understanding of thin film formation. Nevertheless, this complex matter cannot be covered by a single simulation technique. To consider all mechanisms and processes influencing the optical properties of the growing thin films, various common theoretical methods have been combined to a multi-scale model approach. The simulation techniques have been selected in order to describe all processes in the coating chamber, especially the various mechanisms of thin film growth, and to enable the analysis of the resulting structural as well as optical and electronic layer properties. All methods are merged with adapted communication interfaces to achieve optimum compatibility of the different approaches and to generate physically meaningful results. The present contribution offers an approach for the full simulation of an Ion Beam Sputtering (IBS) coating process combining direct simulation Monte Carlo, classical molecular dynamics, kinetic Monte Carlo, and density functional theory. The simulation is performed exemplary for an existing IBS-coating plant to achieve a validation of the developed multi-scale approach. Finally, the modeled results are compared to experimental data. - Highlights: • A model approach for simulating an Ion Beam Sputtering (IBS) process is presented. • In order to combine the different techniques, optimized interfaces are developed. • The transport of atomic species in the coating chamber is calculated. • We modeled structural and optical film properties based on simulated IBS parameter. • The modeled and the experimental refractive index data fit very well.

  4. Synthesis and mechanical properties of boron suboxide thin films

    International Nuclear Information System (INIS)

    Music, Denis; Schneider, Jochen M.; Kugler, Veronika; Nakao, Setsuo; Jin, Ping; Oestblom, Mattias; Hultman, Lars; Helmersson, Ulf

    2002-01-01

    Boron suboxide thin films have been deposited on Si(100) and graphite substrates by reactive rf magnetron sputtering of a sintered B target in an Ar/O 2 atmosphere. X-ray photoelectron spectroscopy, elastic recoil detection analysis, Fourier transform infrared spectroscopy, x-ray diffraction, and transmission electron microscopy were applied to study the influence of the O 2 partial pressure on the film composition and microstructure. BO x thin films with x=[0.02-0.21] and a C impurity of approximately 0.3 at. % were formed by varying the O 2 partial pressure from 7.2x10 -7 to 3.3x10 -2 Pa. All films were amorphous and the films with x≥0.15 contained boric acid on the surface due to a probable chemical reaction with water in laboratory atmosphere. Mechanical properties were evaluated by nanoindentation. As x was increased from 0.02 to 0.21, the elastic modulus decreased from 272 to 109 GPa. The change in the elastic modulus was attributed to the O concentration variations

  5. Mechanical growth and morphogenesis of seashells

    KAUST Repository

    Moulton, D.E.

    2012-10-01

    Seashells grow through the local deposition of mass along the aperture. Many mathematical descriptions of the shapes of shells have been provided over the years, and the basic logarithmic coiling seen in mollusks can be simulated with few parameters. However, the developmental mechanisms underlying shell coiling are largely not understood and the ubiquitous presence of ornamentation such as ribs, tubercles, or spines presents yet another level of difficulty. Here we develop a general model for shell growth based entirely on the local geometry and mechanics of the aperture and mantle. This local description enables us to efficiently describe both arbitrary growth velocities and the evolution of the shell aperture itself. We demonstrate how most shells can be simulated within this framework. We then turn to the mechanics underlying the shell morphogenesis, and develop models for the evolution of the aperture. We demonstrate that the elastic response of the mantle during shell deposition provides a natural mechanism for the formation of three-dimensional ornamentation in shells. © 2012 Elsevier Ltd.

  6. Impact of silver metallization and electron irradiation on the mechanical deformation of polyimide films

    Science.gov (United States)

    Muradov, A. D.; Mukashev, K. M.; Yar-Mukhamedova, G. Sh.; Korobova, N. E.

    2017-11-01

    The impact of silver metallization and electron irradiation on the physical and mechanical properties of polyimide films has been studied. The metal that impregnated the structure of the polyimide substrate was 1-5 μm. The surface coatings contained 80-97% of the relative silver mirror in the visible and infrared regions. Irradiation was performed at the ELU-6 linear accelerator with an average beam electron energy of 2 MeV, an integral current of up to 1000 μA, a pulse repetition rate of 200 Hz, and a pulse duration of 5 μs. The absorbed dose in the samples was 10, 20, 30, and 40 MGy. The samples were deformed at room temperature under uniaxial tension on an Instron 5982 universal testing system. The structural changes in the composite materials that result from the impact of the physical factors were studied using an X-ray diffractometer DRON-2M in air at 293 K using Cu K α radiation (λαCu = 1.5418 Å). A substantial growth of mechanical characteristics resulting from the film metallization, as compared to the pure film, was observed. The growth of the ultimate strength by Δσ = 105 MPa and the plasticity by Δɛ = 75% is connected with the characteristics of the change of structure of the metallized films and the chemical etching conditions. The electron irradiation of the metallized polyimide film worsens its elastic and strength characteristics due to the formation of new phases in the form of silver oxide in the coating. The concentration of these phases increased with increasing dose, which was also the result of the violation of the ordered material structure, namely, the rupture of polyimide macromolecule bonds and the formation of new phases of silver in the coating. A mathematical model was obtained that predicts the elastic properties of silver metallized polyimide films. This model agrees with the experimental data.

  7. Growth and Dissolution of Iron and Manganese Oxide Films

    Energy Technology Data Exchange (ETDEWEB)

    Scot T. Martin

    2008-12-22

    Growth and dissolution of Fe and Mn oxide films are key regulators of the fate and transport of heavy metals in the environment, especially during changing seasonal conditions of pH and dissolved oxygen. The Fe and Mn are present at much higher concentrations than the heavy metals, and, when Fe and Mn precipitate as oxide films, heavy metals surface adsorb or co-precipitate and are thus essentially immobilized. Conversely, when the Fe and Mn oxide films dissolve, the heavy metals are released to aqueous solution and are thus mobilized for transport. Therefore, understanding the dynamics and properties of Fe and Mn oxide films and thus on the uptake and release of heavy metals is critically important to any attempt to develop mechanistic, quantitative models of the fate, transport, and bioavailablity of heavy metals. A primary capability developed in our earlier work was the ability to grow manganese oxide (MnO{sub x}) films on rhodochrosite (MnCO{sub 3}) substrate in presence of dissolved oxygen under mild alkaline conditions. The morphology of the films was characterized using contact-mode atomic force microscopy. The initial growth began by heteroepitaxial nucleation. The resulting films had maximum heights of 1.5 to 2 nm as a result of thermodynamic constraints. Over the three past years, we have investigated the effects of MnO{sub x} growth on the interactions of MnCO{sub 3} with charged ions and microorganisms, as regulated by the surface electrical properties of the mineral. In 2006, we demonstrated that MnO{sub x} growth could induce interfacial repulsion and surface adhesion on the otherwise neutral MnCO{sub 3} substrate under environmental conditions. Using force-volume microscopy (FVM), we measured the interfacial and adhesive forces on a MnO{sub x}/MnCO{sub 3} surface with a negatively charged silicon nitride tip in a 10-mM NaNO3 solution at pH 7.4. The interfacial force and surface adhesion of MnOx were approximately 40 pN and 600 pN, respectively

  8. Pulsed laser thin film growth of di-octyl substituted polyfluorene and its co-polymers

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.K.; Ghosh, K.; Kahol, P.K. [Department of Physics, Astronomy and Materials Science, Missouri State University, Springfield, MO 65897 (United States); Yoon, J. [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Guha, S. [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)], E-mail: guhas@missouri.edu

    2008-08-30

    Matrix-assisted pulsed laser deposition (PLD) allows a controlled layer-by-layer growth of polymer films. Di-octyl substituted polyfluorene (PF8) and its copolymers were deposited as thin films using matrix-assisted PLD by employing a KrF excimer laser with a fluence of 125 mJ/pulses. The optical and structural properties of these films are compared with spincoated films via Raman spectroscopy, absorption and photoluminescence. The Raman spectra of both PLD and spincoated films are similar indicating that the polymer films deposited via PLD maintain their molecular structure. Both the spincoated and the PLD grown PF8 films that were cast from toluene show the presence of the {beta} phase. Benzothiadiazole substituted PF8 (F8BT) and butyl phenyl-substituted PF8 (PFB) PLD grown films show a slightly broader emission compared to the spincoated films, which is attributed to an enhanced intermolecular interaction in the PLD grown thin films.

  9. Pulsed laser thin film growth of di-octyl substituted polyfluorene and its co-polymers

    International Nuclear Information System (INIS)

    Gupta, R.K.; Ghosh, K.; Kahol, P.K.; Yoon, J.; Guha, S.

    2008-01-01

    Matrix-assisted pulsed laser deposition (PLD) allows a controlled layer-by-layer growth of polymer films. Di-octyl substituted polyfluorene (PF8) and its copolymers were deposited as thin films using matrix-assisted PLD by employing a KrF excimer laser with a fluence of 125 mJ/pulses. The optical and structural properties of these films are compared with spincoated films via Raman spectroscopy, absorption and photoluminescence. The Raman spectra of both PLD and spincoated films are similar indicating that the polymer films deposited via PLD maintain their molecular structure. Both the spincoated and the PLD grown PF8 films that were cast from toluene show the presence of the β phase. Benzothiadiazole substituted PF8 (F8BT) and butyl phenyl-substituted PF8 (PFB) PLD grown films show a slightly broader emission compared to the spincoated films, which is attributed to an enhanced intermolecular interaction in the PLD grown thin films

  10. Pulsed laser thin film growth of di-octyl substituted polyfluorene and its co-polymers

    Science.gov (United States)

    Gupta, R. K.; Ghosh, K.; Kahol, P. K.; Yoon, J.; Guha, S.

    2008-08-01

    Matrix-assisted pulsed laser deposition (PLD) allows a controlled layer-by-layer growth of polymer films. Di-octyl substituted polyfluorene (PF8) and its copolymers were deposited as thin films using matrix-assisted PLD by employing a KrF excimer laser with a fluence of 125 mJ/pulses. The optical and structural properties of these films are compared with spincoated films via Raman spectroscopy, absorption and photoluminescence. The Raman spectra of both PLD and spincoated films are similar indicating that the polymer films deposited via PLD maintain their molecular structure. Both the spincoated and the PLD grown PF8 films that were cast from toluene show the presence of the β phase. Benzothiadiazole substituted PF8 (F8BT) and butyl phenyl-substituted PF8 (PFB) PLD grown films show a slightly broader emission compared to the spincoated films, which is attributed to an enhanced intermolecular interaction in the PLD grown thin films.

  11. Fracture mechanisms in biopolymer films using coupling of mechanical analysis and high speed visualization technique

    NARCIS (Netherlands)

    Paes, S.S.; Yakimets, I.; Wellner, N.; Hill, S.E.; Wilson, R.H.; Mitchell, J.R.

    2010-01-01

    The aim of this study was to provide a detailed description of the fracture mechanisms in three different biopolymer thin materials: gelatin, hydroxypropyl cellulose (HPC) and cassava starch films. That was achieved by using a combination of fracture mechanics methodology and in situ visualization

  12. Mechanics of fragmentation of crocodile skin and other thin films

    Science.gov (United States)

    Qin, Zhao; Pugno, Nicola M.; Buehler, Markus J.

    2014-01-01

    Fragmentation of thin layers of materials is mediated by a network of cracks on its surface. It is commonly seen in dehydrated paintings or asphalt pavements and even in graphene or other two-dimensional materials, but is also observed in the characteristic polygonal pattern on a crocodile's head. Here, we build a simple mechanical model of a thin film and investigate the generation and development of fragmentation patterns as the material is exposed to various modes of deformation. We find that the characteristic size of fragmentation, defined by the mean diameter of polygons, is strictly governed by mechanical properties of the film material. Our result demonstrates that skin fragmentation on the head of crocodiles is dominated by that it features a small ratio between the fracture energy and Young's modulus, and the patterns agree well with experimental observations. Understanding this mechanics-driven process could be applied to improve the lifetime and reliability of thin film coatings by mimicking crocodile skin. PMID:24862190

  13. Improved interface growth and enhanced flux pinning in YBCO films deposited on an advanced IBAD-MgO based template

    Science.gov (United States)

    Khan, M. Z.; Zhao, Y.; Wu, X.; Malmivirta, M.; Huhtinen, H.; Paturi, P.

    2018-02-01

    The growth mechanism is studied from the flux pinning point of view in small-scale YBa2Cu3O6+x (YBCO) thin films deposited on a polycrystalline hastelloy with advanced IBAD-MgO based buffer layer architecture. When compared the situation with YBCO films grown on single crystal substrates, the most critical issues that affect the suitable defect formation and thus the optimal vortex pinning landscape, have been studied as a function of the growth temperature and the film thickness evolution. We can conclude that the best critical current property in a wide applied magnetic field range is observed in films grown at relatively low temperature and having intermediate thickness. These phenomena are linked to the combination of the improved interface growth, to the film thickness related crystalline relaxation and to the formation of linear array of edge dislocations that forms the low-angle grain boundaries through the entire film thickness and thus improve the vortex pinning properties. Hence, the optimized buffer layer structure proved to be particularly suitable for new coated conductor solutions.

  14. Postreceptor signaling mechanisms for Growth Hormone.

    Science.gov (United States)

    Roupas, P; Herington, A C

    1994-01-01

    Recent data have shed significant new light on the mechanisms involved in the transmission of a biologic signal by GH. Following ligand-induced dimerization of the GH receptor, multiple cascades are involved in GH signaling. These include activation of nonreceptor tyrosine kinases, in particular JAK2, which is a mechanism shared by the newly described cytokine receptor superfamily. Furthermore, several classic pathways (for example, guanine-nucleotide-binding proteins and protein kinase C), shared by numerous hormones, growth factors, and neurotransmitters, are also involved in many of the actions of GH. The interrelationships between the various signaling pathways for GH have not yet been fully defined. This review briefly summarizes the current state of knowledge with respect to the processes involved in the effects of GH in target cells.

  15. Growth behavior of GaN film along non-polar [1 1 -2 0] directions

    International Nuclear Information System (INIS)

    Gong Xiaojing; Xu Ke; Wang Jianfeng; Yang Hui; Bian Lifeng; Zhang Jingping; Xu Zijian

    2011-01-01

    We studied the atomic assembly mechanisms of non-polar GaN films by the molecular dynamics method as a function of the N:Ga flux ratio at a fixed adatom energy on non-polar planes. Our study revealed that high quality crystal growth occurred only when off-lattice atoms (which are usually associated with amorphous embryos or defect complexes) formed during deposition were able to move to unoccupied lattice sites by thermally activated diffusion processes, which attests to the experimental difficulties in obtaining smooth surfaces due to dense stacking faults lying in non-polar GaN. Furthermore, surface structures on different planes played an important role. We further suggested favorable conditions for growing high quality GaN films and nano-structures along non-polar directions.

  16. Growth and process conditions of aligned and patternable films of iron(III) oxide nanowires by thermal oxidation of iron

    International Nuclear Information System (INIS)

    Hiralal, P; Unalan, H E; Amaratunga, G A J; Wijayantha, K G U; Kursumovic, A; MacManus-Driscoll, J L; Jefferson, D

    2008-01-01

    A simple, catalyst-free growth method for vertically aligned, highly crystalline iron oxide (α-Fe 2 O 3 ) wires and needles is reported. Wires are grown by the thermal oxidation of iron foils. Growth properties are studied as a function of temperature, growth time and oxygen partial pressure. The size, morphology and density of the nanostructures can be controlled by varying growth temperature and time. Oxygen partial pressure shows no effect on the morphology of resulting nanostructures, although the oxide thickness increases with oxygen partial pressure. Additionally, by using sputtered iron films, the possibility of growth and patterning on a range of different substrates is demonstrated. Growth conditions can be adapted to less tolerant substrates by using lower temperatures and longer growth time. The results provide some insight into the mechanism of growth.

  17. Dislocation/hydrogen interaction mechanisms in hydrided nanocrystalline palladium films

    International Nuclear Information System (INIS)

    Amin-Ahmadi, Behnam; Connétable, Damien; Fivel, Marc; Tanguy, Döme; Delmelle, Renaud; Turner, Stuart; Malet, Loic; Godet, Stephane; Pardoen, Thomas; Proost, Joris; Schryvers, Dominique

    2016-01-01

    The nanoscale plasticity mechanisms activated during hydriding cycles in sputtered nanocrystalline Pd films have been investigated ex-situ using advanced transmission electron microscopy techniques. The internal stress developing within the films during hydriding has been monitored in-situ. Results showed that in Pd films hydrided to β-phase, local plasticity was mainly controlled by dislocation activity in spite of the small grain size. Changes of the grain size distribution and the crystallographic texture have not been observed. In contrast, significant microstructural changes were not observed in Pd films hydrided to α-phase. Moreover, the effect of hydrogen loading on the nature and density of dislocations has been investigated using aberration-corrected TEM. Surprisingly, a high density of shear type stacking faults has been observed after dehydriding, indicating a significant effect of hydrogen on the nucleation energy barriers of Shockley partial dislocations. Ab-initio calculations of the effect of hydrogen on the intrinsic stable and unstable stacking fault energies of palladium confirm the experimental observations.

  18. Mechanical and electrochemical characterization of vanadium nitride (VN) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J.C., E-mail: Jcesarca@calima.univalle.edu.co [Grupo de Peliculas Delgadas, Departamento de Fisica, Universidad del Valle, Cali (Colombia); Zambrano, G. [Grupo de Peliculas Delgadas, Departamento de Fisica, Universidad del Valle, Cali (Colombia); Aperador, W. [Ingenieria Mecatronica, Universidad Militar Nueva Granada, Bogota (Colombia); Escobar-Alarcon, L.; Camps, E. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico, DF 11801 (Mexico)

    2011-10-15

    Vanadium nitride (V-N) thin films were grown using a reactive d.c. magnetron sputtering process, from a vanadium target (99.999%) in an Ar/N{sub 2} gas mixture at different deposition bias voltage. Films were deposited onto silicon (1 0 0) and RUS-3 steel substrates at 400 deg. C. Structural, compositional, mechanical and electrochemical characterizations were performed by X-ray diffraction (XRD), elastic forward analysis (EFA), nanoindentation, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves, respectively. X-ray diffraction patterns show the presence of (1 1 1) and (2 0 0) crystallographic orientations associated to the V-N cubic phase. Nanoindentation measurements revealed that when the bias voltage increases from 0 V to -150 V the hardness and elastic modulus are increased from 11 GPa to 20 GPa and from 187 GPa to 221 GPa, respectively. EIS and Tafel curves showed that the corrosion rate of steel, coated with V-N single layer films deposited without bias voltage, diminishes 90% compared to the steel without this coating. On the other hand, when the V-N coating was deposited at the highest d.c. bias voltage (-150 V), the corrosion rate was greater than in the steel coated with zero-voltage (0 V) V-N films. This last result could be attributed to the formation of porosities produced by the ion bombardment during the deposition process.

  19. Mechanical and electrochemical characterization of vanadium nitride (VN) thin films

    International Nuclear Information System (INIS)

    Caicedo, J.C.; Zambrano, G.; Aperador, W.; Escobar-Alarcon, L.; Camps, E.

    2011-01-01

    Vanadium nitride (V-N) thin films were grown using a reactive d.c. magnetron sputtering process, from a vanadium target (99.999%) in an Ar/N 2 gas mixture at different deposition bias voltage. Films were deposited onto silicon (1 0 0) and RUS-3 steel substrates at 400 deg. C. Structural, compositional, mechanical and electrochemical characterizations were performed by X-ray diffraction (XRD), elastic forward analysis (EFA), nanoindentation, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves, respectively. X-ray diffraction patterns show the presence of (1 1 1) and (2 0 0) crystallographic orientations associated to the V-N cubic phase. Nanoindentation measurements revealed that when the bias voltage increases from 0 V to -150 V the hardness and elastic modulus are increased from 11 GPa to 20 GPa and from 187 GPa to 221 GPa, respectively. EIS and Tafel curves showed that the corrosion rate of steel, coated with V-N single layer films deposited without bias voltage, diminishes 90% compared to the steel without this coating. On the other hand, when the V-N coating was deposited at the highest d.c. bias voltage (-150 V), the corrosion rate was greater than in the steel coated with zero-voltage (0 V) V-N films. This last result could be attributed to the formation of porosities produced by the ion bombardment during the deposition process.

  20. Growth Mechanism of Nanowires: Binary and Ternary Chalcogenides

    Science.gov (United States)

    Singh, N. B.; Coriell, S. R.; Su, Ching-Hua; Hopkins, R. H.; Arnold, B.; Choa, Fow-Sen; Cullum, Brian

    2016-01-01

    Semiconductor nanowires exhibit very exciting optical and electrical properties including high transparency and a several order of magnitude better photocurrent than thin film and bulk materials. We present here the mechanism of nanowire growth from the melt-liquid-vapor medium. We describe preliminary results of binary and ternary selenide materials in light of recent theories. Experiments were performed with lead selenide and thallium arsenic selenide systems which are multifunctional material and have been used for detectors, acousto-optical, nonlinear and radiation detection applications. We observed that small units of nanocubes and elongated nanoparticles arrange and rearrange at moderate melt undercooling to form the building block of a nanowire. Since we avoided the catalyst, we observed self-nucleation and uncontrolled growth of wires from different places. Growth of lead selenide nanowires was performed by physical vapor transport method and thallium arsenic selenide nanowire by vapor-liquid-solid (VLS) method. In some cases very long wires (>mm) are formed. To achieve this goal experiments were performed to create situation where nanowires grew on the surface of solid thallium arsenic selenide itself.

  1. Ion-mixing-induced fractal growth in thin alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Liu Baixin (Dept. of Materials Science and Engineering, Tsinghua Univ., Beijing (China) Center of Condensed Matter and Radiation Physics, CCAST (World Lab.), Beijing (China))

    1991-07-01

    Fractal patterns were observed in Ni-Mo and Ag-Co multilayers after ion mixing to a critical dose. The formation of these fractals was through a multinucleation growth process similar to the cluster-diffusion-limited aggregation (CDLA). The Ni-Mo fractals had a fractal dimension of 1.72, being the same as predicted by the CDLA model, while the Co fractals on Ag-Co films had a smaller dimension, because of the magnetic interaction among the aggregating particles. Another study was performed on four magnetic metals, i.e. Fe, Co, Cr and Ni, under similar conditions and a linear correlation between the fractal dimension and the magneton number was discovered. A new fractal structure, i.e. the discontinuously branching tree morphology (DBTM), was formed by interfacial mixing of AgCo/NaCl layered samples. The DBTM patterns emerging in AgCo films consisted of many NaCl single crystals and shared some common features with the Lattice Animals, e.g. the dimension was around 1.59. A semiquantitative analysis was completed to interpret that the fractal dimension increased with increasing ion dose. (orig.).

  2. A study of structural and mechanical properties of nano-crystalline tungsten nitride film synthesis by plasma focus

    Science.gov (United States)

    Hussnain, Ali; Singh Rawat, Rajdeep; Ahmad, Riaz; Hussain, Tousif; Umar, Z. A.; Ikhlaq, Uzma; Chen, Zhong; Shen, Lu

    2015-02-01

    Nano-crystalline tungsten nitride thin films are synthesized on AISI-304 steel at room temperature using Mather-type plasma focus system. The surface properties of the exposed substrate against different deposition shots are examined for crystal structure, surface morphology and mechanical properties using X-ray diffraction (XRD), atomic force microscope, field emission scanning electron microscope and nano-indenter. The XRD results show the growth of WN and WN2 phases and the development of strain/stress in the deposited films by varying the number of deposition shots. Morphology of deposited films shows the significant change in the surface structure with different ion energy doses (number of deposition shots). Due to the effect of different ion energy doses, the strain/stress developed in the deposited film leads to an improvement of hardness of deposited films.

  3. Disilane as a growth rate catalyst of plasma deposited microcrystalline silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrakellis, P.; Amanatides, E., E-mail: lef@plasmatech.gr; Mataras, D. [Department of Chemical Engineering, Plasma Technology Laboratory, University of Patras, P.O. Box 140, 26504 Patras (Greece); Kalampounias, A. G. [University of Ioannina, Dep. of Chemistry, 45110, Ioannina (Greece); Spiliopoulos, N. [Department of Physics, University of Patras, P.O. Box 140, 26504 Patras (Greece); Lahootun, V.; Coeuret, F.; Madec, A. [Air Liquide CRCD,1 chemin de la porte des Loges, Les Loges en Josas, 78354 Jouy en Josas (France)

    2016-07-15

    The effect of small disilane addition on the gas phase properties of silane-hydrogen plasmas and the microcrystalline silicon thin films growth is presented. The investigation was conducted in the high pressure regime and for constant power dissipation in the discharge with the support of plasma diagnostics, thin film studies and calculations of discharge microscopic parameters and gas dissociation rates. The experimental data and the calculations show a strong effect of disilane on the electrical properties of the discharge in the pressure window from 2 to 3 Torr that is followed by significant raise of the electron number density and the drop of the sheaths electric field intensity. Deposition rate measurements show an important four to six times increase even for disilane mole fractions as low as 0.3 %. The deposition rate enhancement was followed by a drop of the material crystalline volume fraction but films with crystallinity above 40 % were deposited with different combinations of total gas pressure, disilane and silane molar ratios. The enhancement was partly explained by the increase of the electron impact dissociation rate of silane which rises by 40% even for 0.1% disilane mole fraction. The calculations of the gas usage, the dissociation and the deposition efficiencies show that the beneficial effect on the growth rate is not just the result of the increase of Si-containing molecules density but significant changes on the species participating to the deposition and the mechanism of the film growth are caused by the disilane addition. The enhanced participation of the highly sticking to the surface radical such as disilylene, which is the main product of disilane dissociation, was considered as the most probable reason for the significant raise of the deposition efficiency. The catalytic effect of such type of radical on the surface reactivity of species with lower sticking probability is further discussed, while it is also used to explain the restricted

  4. Disilane as a growth rate catalyst of plasma deposited microcrystalline silicon thin films

    Science.gov (United States)

    Dimitrakellis, P.; Kalampounias, A. G.; Spiliopoulos, N.; Amanatides, E.; Mataras, D.; Lahootun, V.; Coeuret, F.; Madec, A.

    2016-07-01

    The effect of small disilane addition on the gas phase properties of silane-hydrogen plasmas and the microcrystalline silicon thin films growth is presented. The investigation was conducted in the high pressure regime and for constant power dissipation in the discharge with the support of plasma diagnostics, thin film studies and calculations of discharge microscopic parameters and gas dissociation rates. The experimental data and the calculations show a strong effect of disilane on the electrical properties of the discharge in the pressure window from 2 to 3 Torr that is followed by significant raise of the electron number density and the drop of the sheaths electric field intensity. Deposition rate measurements show an important four to six times increase even for disilane mole fractions as low as 0.3 %. The deposition rate enhancement was followed by a drop of the material crystalline volume fraction but films with crystallinity above 40 % were deposited with different combinations of total gas pressure, disilane and silane molar ratios. The enhancement was partly explained by the increase of the electron impact dissociation rate of silane which rises by 40% even for 0.1% disilane mole fraction. The calculations of the gas usage, the dissociation and the deposition efficiencies show that the beneficial effect on the growth rate is not just the result of the increase of Si-containing molecules density but significant changes on the species participating to the deposition and the mechanism of the film growth are caused by the disilane addition. The enhanced participation of the highly sticking to the surface radical such as disilylene, which is the main product of disilane dissociation, was considered as the most probable reason for the significant raise of the deposition efficiency. The catalytic effect of such type of radical on the surface reactivity of species with lower sticking probability is further discussed, while it is also used to explain the restricted

  5. Anomalous growth of HfAl3 in thin films

    International Nuclear Information System (INIS)

    Lever, R.F.; Howard, J.K.; Chu, W.K.; Smith, P.J.

    1977-01-01

    Anomalous growth of HfAl 3 is observed on 400degreeC annealing of evaporated thin-film samples consisting of 900 A aluminum, on 1000 A hafnium, 6000 A aluminum and SiO 2 substrates. A continuous layer of HfAl 3 forms at the aluminum--hafnium interface nearer the surface, but not at the deeper interface. The surface HfAl 3 layer then continues to grow, fed by diffusion of underlying aluminum through the intervening hafnium layer. Needlelike precipitates of HfAl 3 are formed along the underlying aluminum grain boundaries. Observations are made by nuclear backscattering, Auger electron spectroscopy, and transmission electron microscopy. Similar behavior is observed in Al--Zr--Al layers

  6. Epitaxial growth of atomically flat gadolinia-doped ceria thin films by pulsed laser deposition

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Pryds, Nini; Schou, Jørgen

    2011-01-01

    Epitaxial growth of Ce0.8Gd0.2O2(CGO) films on (001) TiO2-terminated SrTiO3 substrates by pulsed laser deposition was investigated using in situ reflective high energy electron diffraction. The initial film growth shows a Stransky–Krastanov growth mode. However, this three-dimensional island...... formation is replaced by a two-dimensional island nucleation during further deposition, which results in atomically smooth CGO films. The obtained high-quality CGO films may be attractive for the electrolyte of solid-oxide fuel cells operating at low temperature....

  7. Growth mode and texture development in TiN films during magnetron sputtering - An in situ synchrotron radiation study

    CERN Document Server

    Schell, N; Matz, W; Chevallier, J

    2003-01-01

    For the materials research experimental station of the Rossendorf beamline ROBL at the European Synchrotron Radiation Facility in Grenoble, France, a two magnetron sputter deposition chamber for in situ study of film growth by synchrotron X-ray diffraction and reflectivity was developed. It allows high-quality depositions of compound films and multilayers. Heteroepitaxial layer-by-layer growth of TiN on single crystal MgO(0 0 1) was observed by real-time specular X-ray reflectivity showing characteristic oscillations. The pseudomorphic growth was confirmed by high-resolution TEM micrographs. During growth on amorphous SiO sub 2 on Si(0 0 1) substrates, the microstructural development of TiN films was studied in situ as a function of film thickness. With the deposition parameters chosen, a crossover was observed: grains with a (0 0 2) plane parallel to the film surface dominate at small thicknesses, while, at larger thicknesses, (1 1 1) grains dominate. Recrystallisation was identified as a mechanism that cont...

  8. In Situ Monitoring and Characterization of Superhard Thin-Film Growth Under Non-Equilibrium Conditions

    National Research Council Canada - National Science Library

    Tsong, I

    2000-01-01

    .... Both of these techniques were applied to the CVD growth of boron and GaN films. We have synthesized novel precursors of C3N3P, Si4CN4, LiBC4N4, BC3N3, BeC2N2, MgC2N2 for CVD growth of films with properties of superhardness...

  9. Growth, structuring and characterisation of all-oxide thin film devices prepared by pulsed laser deposition

    NARCIS (Netherlands)

    Cillessen, J.F.M.; Wolf, R.M.; Giesbers, J.B.; Blom, P.W.M.; Grosse Holz, K.O.; Pastoor, E.

    The combination of a variety of oxidic thin films in two materials systems is described. The first one focuses on the growth of BaZrO3 on SrTiO3 (both perovskites) and the use of these stacks as a substrate for the growth of magnetic ferrite spinel films. The second system shows the combination of

  10. Mechanical and thermal properties of physically-blended-plastic films

    International Nuclear Information System (INIS)

    Abu Issa, M. S.

    1983-10-01

    Low density polyethylene (LDPE) and isotactic polypropylene (PP) blend were produced in film form and were characterized by a number of techniques such as wide-angle x-ray diffraction (WAXD), differential thermal analysis (DTA), scanning electron microscopy (SEM), and instron tensile testing. Results of WAXD and DTA showed conclusively that the two components in the blend are incompatible. SEM micrographs indicated that the 60/40 and 40/60 PP/PE blends show approximately fine homogeneous dispersion of the minor component into the matrix of the major component. The mechanical properties of the blend films improved with respect to the PE homo polymer. The improvement was more remarkable with the increase of the PP component in the blend. Results obtained in this work were explained in terms of crystallinity and the crystallite orientation. 28 refs., 29 figs., 5 tabs. (A.M.H.)

  11. Modification of mechanical and thermal property of chitosan-starch blend films

    Science.gov (United States)

    Tuhin, Mohammad O.; Rahman, Nazia; Haque, M. E.; Khan, Ruhul A.; Dafader, N. C.; Islam, Rafiqul; Nurnabi, Mohammad; Tonny, Wafa

    2012-10-01

    Chitosan-starch blend films (thickness 0.2 mm) of different composition were prepared by casting and their mechanical properties were studied. To improve the properties of chitosan-starch films, glycerol and mustard oil of different composition were used. Chitosan-starch films, incorporated with glycerol and mustard oil, were further modified with monomer 2-hydroxyethyl methacrylate (HEMA) using gamma radiation. The modified films showed improvement in both tensile strength and elongation at break than the pure chitosan-starch films. Water uptake of the films reduced significantly than the pure chitosan-starch film. Thermo gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) showed that the modified films experience less thermal degradation than the pure films. Scanning electron microscopy (SEM) and FTIR were used to investigate the morphology and molecular interaction of the blend film, respectively.

  12. Effects of Loading Frequency and Film Thickness on the Mechanical Behavior of Nanoscale TiN Film

    Science.gov (United States)

    Liu, Jin-na; Xu, Bin-shi; Wang, Hai-dou; Cui, Xiu-fang; Jin, Guo; Xing, Zhi-guo

    2017-09-01

    The mechanical properties of a nanoscale-thickness film material determine its reliability and service life. To achieve quantitative detection of film material mechanical performance based on nanoscale mechanical testing methods and to explore the influence of loading frequency of the cycle load on the fatigue test, a TiN film was prepared on monocrystalline silicon by magnetron sputtering. The microstructure of the nanoscale-thickness film material was characterized by using scanning electron microscopy and high-resolution transmission electron microscopy. The residual stress distribution of the thin film was obtained by using an electronic film stress tester. The hardness values and the fatigue behavior were measured by using a nanomechanical tester. Combined with finite element simulation, the paper analyzed the influence of the film thickness and loading frequency on the deformation, as well as the equivalent stress and strain. The results showed that the TiN film was a typical face-centered cubic structure with a large amount of amorphous. The residual compressive stress decreased gradually with increasing thin film thickness, and the influence of the substrate on the elastic modulus and hardness was also reduced. A greater load frequency would accelerate the dynamic fatigue damage that occurs in TiN films.

  13. Domain epitaxial growth of ferroelectric films of barium strontium titanate on sapphire

    Science.gov (United States)

    Tumarkin, A. V.; Odinets, A. A.

    2018-01-01

    A model of the epitaxial growth of crystalline multicomponent films on single-crystal substrates with a domain correspondence is presented using a solid solution of barium strontium titanate on sapphire substrates ( r cut). The domain epitaxial growth suggests the matching of the lattice planes of the film and the substrate having similar structures by comparison of domain multiple of an integral number of the interplanar spacings. Variation of the component composition of the solid solution enables changes in the domain size in the range sufficient for epitaxial growth. This method can be used to project the epitaxial growth of films of various solid solutions on single-crystal substrates.

  14. Effects of Sputtering Parameters on AlN Film Growth on Flexible Hastelloy Tapes by Two-Step Deposition Technique.

    Science.gov (United States)

    Peng, Bin; Gong, Dongdong; Zhang, Wanli; Jiang, Jianying; Shu, Lin; Zhang, Yahui

    2016-08-10

    AlN thin films were deposited on flexible Hastelloy tapes and Si (100) substrate by middle-frequency magnetron sputtering. A layer of Y₂O₃ films was used as a buffer layer for the Hastelloy tapes. A two-step deposition technique was used to prepare the AlN films. The effects of deposition parameters such as sputtering power, N₂/Ar flow rate and sputtering pressure on the microstructure of the AlN thin films were systematically investigated. The results show that the dependency of the full width at half maximum (FWHM) of AlN/Y₂O₃/Hastelloy on the sputtering parameters is similar to that of AlN/Si (100). The FWHM of the AlN (002) peak of the prepared AlN films decreases with increasing sputtering power. The FWHM decreases with the increase of the N₂/Ar flow rate or sputtering pressure, and increases with the further increase of the N₂/Ar flow rate or sputtering pressure. The FWHM of the AlN/Y₂O₃/Hastelloy prepared under optimized parameters is only 3.7° and its root mean square (RMS) roughness is 5.46 nm. Based on the experimental results, the growth mechanism of AlN thin films prepared by the two-step deposition process was explored. This work would assist us in understanding the AlN film's growth mechanism of the two-step deposition process, preparing highly c-axis-oriented AlN films on flexible metal tapes and developing flexible surface acoustic wave (SAW) sensors from an application perspective.

  15. Growth, surface treatment and characterization of polycrystalline lead iodide thick films prepared using close space deposition technique

    International Nuclear Information System (INIS)

    Zhu, Xinghua; Sun, Hui; Yang, Dingyu; Zheng, Xiaolin

    2012-01-01

    Lead iodide (PbI 2 ) polycrystalline thick films were fabricated on glass substrates with a conductive indium–tin-oxide layer using a close space deposition technique. The morphology of the as-deposited PbI 2 films is typically and highly oriented polycrystalline structure, made up of microcrystal platelets upright on the substrate plane. Two techniques including the surface mechanical cutting and after-growth cadmium telluride coating were employed to improve the films′ surface properties. It was shown that both of the film surface treatment methods markedly decreased the dark current of PbI 2 films. The photo-to-dark current ratio of about 2.05 under 241 Am γ-ray source with activity of 2.78 μCi irradiation was obtained from the film treated using both surface cutting and after-growth CdTe coating. Charge transport characteristics of these films were measured and the hole mobility 7.7×10 −2 –1.67×10 −1 cm 2 /V s was estimated.

  16. Advantages of dual-laser ablation in the growth of multicomponent thin films

    Science.gov (United States)

    Mukherjee, Devajyoti; Hyde, Robert; Mukherjee, Pritish; Witanachchi, Sarath

    2012-07-01

    We report the use of a dual-laser deposition process to grow stoichiometric films of the piezoelectric material PbZr0.52Ti0.48O3 (PZT) and the thermoelectric material Ba8Ga16Ge30. High volatility of Pb and Ba in these materials leads to non-stoichiometric growth in conventional PLD processes. Dual-laser ablation process preserves the Pb and Ba stoichiometry while significantly reducing the thickness variation and particulate density on the deposited films. This lead to the growth of smooth uniform films with enhanced ferroelectric and electrical properties. The dual-laser ablation combines the pulses of a KrF excimer laser (248 nm wavelength, 30 ns pulse width) and a CO2 laser (10.6 μm wavelength, 250 ns pulse width) where the beams are spatially overlapped on the ablation target and temporally delayed. At an optimum delay that is dependent on the physical properties of the material, CO2 pulse energy is coupled into the plume, generating a high temperature plasma (>25,000K). Laser-target interaction studies have shown the evaporation to be stoichiometric. Emission spectroscopy studies have shown ten-fold increase in emission intensities in dual-laser ablation while time-gated 2D ICCD imaging studies revealed the plume expansion to be stoichiometric over a large cone-angle of the plume under these conditions. Time-of-flight investigations in concert with hydrodynamic modeling provided a clear understanding of the mechanism of dual-laser ablation. Furthermore, plasma generated in the process is highly ionized (>75%) leading to films with high density and crystallinity. This paper will show the enhancement in properties attainable by the dual-laser ablation process in comparison to the single laser ablation.

  17. Oriented growth of thin films of samarium oxide by MOCVD

    Indian Academy of Sciences (India)

    Unknown

    Infrared spectroscopic study reveals that films grown above 600°C are free of carbon. Keywords. MOCVD; thin films .... Simultaneous thermogravimetry and differential thermal analysis (TG/DTA) of the complex was carried ..... quality thin films of rare earth oxides by MOCVD, using the phenanthroline adducts of pentadionate ...

  18. Tribological behavior and film formation mechanisms of carbon nanopearls

    Science.gov (United States)

    Hunter, Chad Nicholas

    Carbon nanopearls (CNPs) are amorphous carbon spheres that contain concentrically-oriented nanometer-sized graphitic flakes. Because of their spherical shape, size (˜150 nm), and structure consisting of concentrically oriented nano-sized sp2 flakes, CNPs are of interest for tribological applications, in particular for use in solid lubricant coatings. These studies were focused on investigating mechanisms of CNP lubrication, development of methods to deposit CNP onto substrates, synthesizing CNP-gold hybrid films using Matrix Assisted Pulsed Laser Evaporation (MAPLE) and magnetron sputtering, and studying plasmas and other species present during film deposition using an Electrostatic Quadrupole Plasma (EQP) analyzer. CNPs deposited onto silicon using drop casting with methanol showed good lubricating properties in sliding contacts under dry conditions, where a transfer film was created in which morphology changed from nano-sized spheres to micron-sized agglomerates consisting of many highly deformed CNPs in which the nano-sized graphene flakes are sheared from the wrapped layer structure of the CNPs. The morphology of carbon nanopearl films deposited using a MAPLE system equipped with a 248 nm KrF excimer laser source was found to be influenced by multiple factors, including composition of the matrix solvent, laser energy and repetition rate, background pressure, and substrate temperature. The best parameters for depositing CNP films that are disperse, droplet-free and have the maximum amount of material deposited are as follows: toluene matrix, 700 mJ, 1 Hz, 100°C substrate temperature, and unregulated vacuum pressure. During depositions using MAPLE and sputtering in argon, electron ionization of toluene vapor generated from the MAPLE target and charge exchange reactions between toluene vapor and the argon plasma generated by the magnetron caused carbon to be deposited onto the gold sputter target. Thin films deposited under these conditions contained high

  19. Physical-Mechanical Properties And Microstructure Of Breadfruit Starch Edible Films With Various Plasticizer

    Directory of Open Access Journals (Sweden)

    Cut Fatimah Zuhra Marpongahtun

    2013-08-01

    Full Text Available Breadfruit contains starch can be used as raw material of edible film. Research on preparation of edible films using various types of plasticizer (xylitol, sorbitol and PEG 400 has been done. The edible films were evaluated of physical-mechanical properties and microstructure. The results of this study indicate that the addition of plasticizer effect on the physical and mechanical characteristics, the edible film thickness, tensile strength and water vapor transmission rate greater using PEG 400 but percent elongation smaller than xylitol and sorbitol. Surface analysis of film was performed using Scanning Electron Microscopy (SEM method.Keyword : Edible Film; Pati Sukun; Plasticizer; Silitol; Sorbitol ; PEG 400

  20. Mechanisms of Atmospherically Relevant Cluster Growth.

    Science.gov (United States)

    Bzdek, Bryan R; DePalma, Joseph W; Johnston, Murray V

    2017-08-15

    Atmospheric aerosols impact global climate either directly by scattering solar radiation or indirectly by serving as cloud condensation nuclei, which influence cloud albedo and precipitation patterns. Our scientific understanding of these impacts is poor relative to that of, for instance, greenhouse gases, in part because it is difficult to predict particle number concentrations. One important pathway by which particles are added to the atmosphere is new particle formation, where gas phase precursors form molecular clusters that subsequently grow to the climatically relevant size range (50-100 nm diameter). It is predicted that up to 50% of atmospheric particles arise from this process, but the key initial chemical processes are poorly resolved. In general, a combination of inorganic and organic molecules are thought to contribute to new particle formation, but the chemical composition of molecular clusters and pathways by which they grow to larger sizes is unclear. Cluster growth is a key component of new particle formation, as it governs whether molecular clusters will become climatically relevant. This Account discusses our recent work to understand the mechanisms underlying new particle growth. Atmospherically relevant molecular clusters containing the likely key contributors to new particle formation (sulfuric acid, ammonia, amines, and water) were investigated experimentally by Fourier transform mass spectrometry as well as computationally by density functional theory. Our laboratory experiments investigated the molecular composition of charged clusters, the molecular pathways by which these clusters may grow, and the kinetics of base incorporation into them. Computational chemistry allowed confirmation and rationalization of the experimental results for charged clusters and extension of these principles to uncharged and hydrated clusters that are difficult to study by mass spectrometry. This combination of approaches enabled us to establish a framework for

  1. The mechanism of sputter-induced orientation change in YBCO films on MgO (001)

    International Nuclear Information System (INIS)

    Huang, Y.; Vuchic, B.V.; Baldo, P.; Merkle, K.L.; Buchholz, D.B.; Mahajan, S.; Lei, J.S.; Markworth, P.R.; Chang, R.P.H.

    1996-12-01

    The mechanisms of the sputter-induced orientation change in YBa 2 Cu 3 O 7-x (YBCO) films grown on MgO (001) substrates by pulsed organometallic beam epitaxy (POMBE) are investigated by x-ray diffraction. Rutherford backscatter spectroscopy (RBS), cross-section TEM (XTEM) and microanalysis. It is found that the W atom implantation concurring with the ion sputtering plays an important role in effecting the orientation change. This implantation changes the surface structure of the substrate and induces an intermediate layer in the initial growth of the YBCO film, which in turn acts as a template that induces the orientation change. It seems that the surface morphology change caused by ion sputtering has only a minor effect on the orientation change

  2. Plasticity mechanisms in ultrafine grained freestanding aluminum thin films revealed by in-situ transmission electron microscopy nanomechanical testing

    International Nuclear Information System (INIS)

    Idrissi, Hosni; Kobler, Aaron; Amin-Ahmadi, Behnam; Schryvers, Dominique; Coulombier, Michael; Pardoen, Thomas; Galceran, Montserrat; Godet, Stéphane; Raskin, Jean-Pierre; Kübel, Christian

    2014-01-01

    In-situ bright field transmission electron microscopy (TEM) nanomechanical tensile testing and in-situ automated crystallographic orientation mapping in TEM were combined to unravel the elementary mechanisms controlling the plasticity of ultrafine grained Aluminum freestanding thin films. The characterizations demonstrate that deformation proceeds with a transition from grain rotation to intragranular dislocation glide and starvation plasticity mechanism at about 1% deformation. The grain rotation is not affected by the character of the grain boundaries. No grain growth or twinning is detected

  3. Physical-Mechanical Properties And Microstructure Of Breadfruit Starch Edible Films With Various Plasticizer

    OpenAIRE

    Cut Fatimah Zuhra Marpongahtun

    2013-01-01

    Breadfruit contains starch can be used as raw material of edible film. Research on preparation of edible films using various types of plasticizer (xylitol, sorbitol and PEG 400) has been done. The edible films were evaluated of physical-mechanical properties and microstructure. The results of this study indicate that the addition of plasticizer effect on the physical and mechanical characteristics, the edible film thickness, tensile strength and water vapor transmission rate greater using PEG...

  4. Mechanisms of lubrication and wear of a bonded solid lubricant film

    Science.gov (United States)

    Fusaro, R. L.

    1980-01-01

    To obtain a better understanding of how bonded solid lubricant films lubricate and wear (in general), the tribological properties of polyimide-bonded graphite fluoride films were studied (in specific). A pin-on-disk type of testing apparatus was used; but in addition to sliding a hemispherically tipped rider, a rider with a 0.95 mm diameter flat area was slid against the film. This was done so that a lower, less variable contact stress could be achieved. Two stages of lubrication occurred. In the first, the film supported the load. The lubricating mechanism consisted of the shear of a thin surface layer (of the film) between the rider and the bulk of the film. The second occurred after the bonded film had worn to the substrate, and consisted of the shear of very thin lubricant films between the rider and flat plateaus generated on the metallic substrate asperities. The film wear mechanism was strongly dependent on contact stress.

  5. Mechanical design problems associated with turbopump fluid film bearings

    Science.gov (United States)

    Evces, Charles R.

    1990-01-01

    Most high speed cryogenic turbopumps for liquid propulsion rocket engines currently use ball or roller contact bearings for rotor support. The operating speeds, loads, clearances, and environments of these pumps combine to make bearing wear a limiting factor on turbopump life. An example is the high pressure oxygen turbopump (HPOTP) used in the Space Shuttle Main Engine (SSME). Although the HPOTP design life is 27,000 seconds at 30,000 rpms, or approximately 50 missions, bearings must currently be replaced after 2 missions. One solution to the bearing wear problem in the HPOTP, as well as in future turbopump designs, is the utilization of fluid film bearings in lieu of continuous contact bearings. Hydrostatic, hydrodynamic, and damping seal bearings are all replacement candidates for contact bearings in rocket engine high speed turbomachinery. These three types of fluid film bearings have different operating characteristics, but they share a common set of mechanical design opportunities and difficulties. Results of research to define some of the mechanical design issues are given. Problems considered include transient strat/stop rub, non-operational rotor support, bearing wear inspection and measurement, and bearing fluid supply route. Emphasis is given to the HPOTP preburner pump (PBP) bearing, but the results are pertinent to high-speed cryogenic turbomachinery in general.

  6. Dynamic Mechanical Properties of Bio-Polymer Graphite Thin Films

    Science.gov (United States)

    Saddam Kamarudin, M.; Rus, Anika Zafiah M.; Munirah Abdullah, Nur; Abdullah, M. F. L.

    2017-08-01

    Waste cooking oil is used as the main substances in producing graphite biopolymer thin films. Biopolymer is produce from the reaction of bio-monomer and cross linker with the ratio of 2:1 and addition of graphite with an increment of 2% through a slip casting method. The morphological surface properties of the samples are observed by using Scanning Electron Microscope (SEM). It is shown that the graphite particle is well mixed and homogenously dispersed in biopolymer matrix. Meanwhile, the mechanical response of materials by monitoring the change in the material properties in terms of frequency and temperature of the samples were determined using Dynamic Mechanical Analysis (DMA). The calculated cross-linked density of biopolymer composites revealed the increment of graphite particle loading at 8% gives highest results with 260.012 x 103 M/m3.

  7. Modeling and analysis of film composition on mechanical properties of maize starch based edible films.

    Science.gov (United States)

    Prakash Maran, J; Sivakumar, V; Thirugnanasambandham, K; Kandasamy, S

    2013-11-01

    The present study investigates the influence of composition (content of maize starch (1-3 g), sorbitol (0.5-1.0 ml), agar (0.5-1.0 g) and tween-80 (0.1-0.5 ml)) on the mechanical properties (tensile strength, elongation, Young's modulus, puncture force and puncture deformation) of the maize starch based edible films using four factors with three level Box-Behnken design. The edible films were obtained by casting method. The results showed that, tween-80 increases the permeation of sorbitol in to the polymer matrix. Increasing concentration of sorbitol (hydrophilic nature and plasticizing effect of sorbitol) decreases the tensile strength, Young's modulus and puncture force of the films. The results were analyzed by Pareto analysis of variance (ANOVA) and second order polynomial models were obtained for all responses with high R(2) values (R(2)>0.95). 3D response surface plots were constructed to study the relationship between process variables and the responses. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Pulsed laser deposition growth of FeSb2 films for thermoelectric applications

    DEFF Research Database (Denmark)

    Sun, Ye; Canulescu, Stela; Sun, Peijie

    2011-01-01

    FeSb2 films were produced in a low-pressure Ar environment by pulsed laser deposition at 355 nm. The influence of growth parameters such as substrate temperature, Ar pressure and deposition time on the growth of FeSb2 films was studied. Nearly phase-pure FeSb2 films with thicknesses of 100–400 nm...... properties of FeSb2 films if they are to eventually reach thermoelectric applications at cryogenic temperatures.......FeSb2 films were produced in a low-pressure Ar environment by pulsed laser deposition at 355 nm. The influence of growth parameters such as substrate temperature, Ar pressure and deposition time on the growth of FeSb2 films was studied. Nearly phase-pure FeSb2 films with thicknesses of 100–400 nm...... were produced at 425 °C with an Ar pressure of 1.5–2 Pa. Thermal transport and Hall measurements were performed to explore the thermoelectric transport properties of the FeSb2 films. A maximum thermopower of 120 μVK−1 at 40 K was obtained. In general it is highly important to understand the growth...

  9. Large area porous gold films deposited by evaporation-induced colloidal crystal growth.

    Science.gov (United States)

    Zhang, Renyun; Hummelgård, Magnus; Olin, Håkan

    2009-12-01

    Films that are nanostructured in two- or three-dimensions, such as porous ones, are made by several methods including templated growth and self-assembly. Here, we report on a new method that is based on evaporation-induced growth of nanoparticle gold films on a water surface. The film growth was done in a similar way to the well-known evaporation-induced colloidal crystal growth method, but in contrast, we did not directly deposit the film on a solid substrate. The films were instead created on top of a water surface. After the growth process, the films were deposited directly on substrates by a simple pick-up procedure. The deposited porous gold films were uniform with a thickness of 100 nm and had a sheet resistance of 100 Omega/sq. There are several advantages with our method, including simplicity of the protocol, large film area, flexibility in the choice of substrate to be coated, and the ability for multilayer coatings. The latter points to opportunities for fabrication of multilayer 3D porous structure, which may have wide applications in sensors and electrochemical determinations.

  10. Edible Packaging Film Derived from Mechanically Deboned Chicken Meat Proteins: Effect of Transglutaminase on Physicochemical Properties

    Science.gov (United States)

    Yayli, Damla; Turhan, Sadettin; Saricaoglu, Furkan Turker

    2017-01-01

    In this study, effect of transglutaminase (TGase) addition on physical, water barrier, optical and mechanical properties of mechanically deboned chicken meat protein (MDCM-P) films was investigated. When TGase was added to the films, the thickness increased, but the solubility decreased. Films treated with TGase exhibited higher water vapor permeability than control film (pfilms decreased, but a* and b* values increased. All films showed very good barrier properties against UV light. The highest tensile strength was obtained in MDCM-P films containing 3% TGase (pfilm matrix. TGase treated films showed smoother and ordered surface structure and homogeneous and compact microstructure. The results indicated that TGase use can be an effective approach in improving the solubility and mechanical properties of MDCM-P films. PMID:29147086

  11. Thin film modeling of crystal dissolution and growth in confinement

    Science.gov (United States)

    Gagliardi, Luca; Pierre-Louis, Olivier

    2018-01-01

    We present a continuum model describing dissolution and growth of a crystal contact confined against a substrate. Diffusion and hydrodynamics in the liquid film separating the crystal and the substrate are modeled within the lubrication approximation. The model also accounts for the disjoining pressure and surface tension. Within this framework, we obtain evolution equations which govern the nonequilibrium dynamics of the crystal interface. Based on this model, we explore the problem of dissolution under an external load, known as pressure solution. We find that in steady state, diverging (power-law) crystal-surface repulsions lead to flat contacts with a monotonic increase of the dissolution rate as a function of the load. Forces induced by viscous dissipation then surpass those due to disjoining pressure at large enough loads. In contrast, finite repulsions (exponential) lead to sharp pointy contacts with a dissolution rate independent of the load and the liquid viscosity. Ultimately, in steady state, the crystal never touches the substrate when pressed against it. This result is independent from the nature of the crystal-surface interaction due to the combined effects of viscosity and surface tension.

  12. Mechanical Properties of Khaya and Albizia Films Intended for ...

    African Journals Online (AJOL)

    Addition of albizia improved the film forming properties of khaya gum and imparted increasing toughness, flexibility and elasticity to the films. Albizia thus appear to be a better film coating material than khaya gum. The hardness of the films was not significantly affected by increase in albizia concentration. Inclusion of HPMC ...

  13. Growth mode and texture study in vanadium dioxide thin films deposited by magnetron sputtering

    International Nuclear Information System (INIS)

    Wei Xiongbang; Wu Zhiming; Xu Xiangdong; Tao Wang; Tang Jingjing; Li Weizhi; Jiang Yadong

    2008-01-01

    Vanadium dioxide (VO 2 ) films with thicknesses of 80, 440 and 1000 nm were deposited on glass substrates by reactive dc magnetron sputtering. The crystallization, surface morphology and structural features were studied by x-ray diffraction, atomic force microscope and scanning electron microscope. Results revealed that the structural features of VO 2 films strongly depend on the film thickness. The grain size and the crystallization extent increase with the increase in film thickness. The growth of VO 2 was demonstrated to be an obvious 'columnar' growth perpendicular to the surface of the glass substrate. Analyses of square resistance and its temperature dependence demonstrated that the thickness of VO 2 films plays an important role in their electric properties. With increasing film thickness, the square resistance decreases, the temperature coefficient of the square resistance increases and the metal-semiconductor phase transition becomes obvious

  14. Heteroepitaxial silicon film growth at 600 oC from an Al-Si eutectic melt

    International Nuclear Information System (INIS)

    Chaudhari, P.; Shim, Heejae; Wacaser, Brent A.; Reuter, Mark C.; Murray, Conal; Reuter, Kathleen B.; Jordan-Sweet, Jean; Ross, Frances M.; Guha, Supratik

    2010-01-01

    A method for growing heteroepitaxial Si films on sapphire was developed using a 6 nm thin Al layer at substrate temperature of 600 o C. Subsequently, the growth of Si nanowires was demonstrated on these films at 490 o C without breaking vacuum. We characterized the properties of the Si films by Raman scattering, X-ray diffraction and transmission electron microscopy and show that the crystal quality and dopant control are promising for photovoltaic applications.

  15. Growth of α-sexithiophene nanostructures on C60 thin film layers

    DEFF Research Database (Denmark)

    Radziwon, Michal Jędrzej; Madsen, Morten; Balzer, Frank

    2014-01-01

    Organic molecular beam grown -sexithiophene (-6T) forms nanostructured thin films on buckminsterfullerene (C60) thin film layers. At substrate temperatures of 300K during growth a rough continuous film is observed, which develop to larger elongated islands and dendritic- as well as needle like ...... fluorescence polarimetry measurements the in-plane orientation of the crystalline sites within the needle like structures is determined. The polarimetry investigations strongly indicate that the needle like structures consist of lying molecules....

  16. Growth techniques used to develop CDS/CDTE thin film solar cells ...

    African Journals Online (AJOL)

    Growth techniques used to develop CDS/CDTE thin film solar cells: a review. ... Techniques such as molecular beam epitaxy (MBE), metal organic chemical vapour deposition (MOCVD) called melt growth or Bridgman are well known as high quality semiconductor growth techniques. One of the limitations of these ...

  17. Growth of graphene films from non-gaseous carbon sources

    Science.gov (United States)

    Tour, James; Sun, Zhengzong; Yan, Zheng; Ruan, Gedeng; Peng, Zhiwei

    2015-08-04

    In various embodiments, the present disclosure provides methods of forming graphene films by: (1) depositing a non-gaseous carbon source onto a catalyst surface; (2) exposing the non-gaseous carbon source to at least one gas with a flow rate; and (3) initiating the conversion of the non-gaseous carbon source to the graphene film, where the thickness of the graphene film is controllable by the gas flow rate. Additional embodiments of the present disclosure pertain to graphene films made in accordance with the methods of the present disclosure.

  18. Epitaxial growth of single-crystalline Ni46Co4Mn37In13 thin film and investigation of its magnetoresistance

    Directory of Open Access Journals (Sweden)

    Chao Jing

    2014-02-01

    Full Text Available Single-crystalline thin film of Ni46Co4Mn37In13 alloy grown on MgO(0 0 1 was prepared by Pulsed Laser Deposition (PLD method. The epitaxial growth process was monitored by in situ Reflection High Energy Electron Diffraction (RHEED. Structure measurements reveal that the single-crystalline Ni46Co4Mn37In13 film could be stabilized on MgO(0 0 1 as a face-centered-cubic (fcc structure. From the evolution of RHEED, it can be deduced from the patterns that Volmer-Weber growth mechanism (3-D dominates at the initial stage. Then, it becomes layer-by-layer growth mechanism (2-D with the increase of the film thickness. Lastly, growth mechanism converts back to 3-D when the film is thick enough. Both electrical resistance and magnetoresistance (MR were measured at various temperatures using Physical Property Measurement System (PPMS. The electrical resistance measurement indicates that the film sample does not have martensitic transformation in the measurement temperature range. However, with the temperature increasing, the film sample exhibits a transition from metallic to semiconductor-like properties. Moreover, a small negative magnetoresistance was observed at different temperature, which can be explained by the spin-dependent scattering of the conduction electrons.

  19. Growth and characterization of V2 O5 thin film on conductive electrode.

    Science.gov (United States)

    Mola, Genene T; Arbab, Elhadi A A; Taleatu, Bidini A; Kaviyarasu, K; Ahmad, Ishaq; Maaza, M

    2017-02-01

    Vanadium pentoxide V 2 O 5 thin films were grown at room temperature on ITO coated glass substrates by electrochemical deposition. The resulting films were annealed at 300, 400 and 500°C for 1 h in ambient environment. The effect of heat treatment on the films properties such as surface morphology, crystal structure, optical absorption and photoluminescence were investigated. The x-ray diffraction study showed that the films are well crystallized with temperatures. Strong reflection from plane (400) indicated the film's preferred growth orientation. The V 2 O 5 films are found to be highly transparent across the visible spectrum and the measured photoluminescence quenching suggested the film's potential application in OPV device fabrication. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  20. HVPE of aluminum nitride, film evaluation and multiscale modeling of the growth process

    Science.gov (United States)

    Pons, M.; Su, J.; Chubarov, M.; Boichot, R.; Mercier, F.; Blanquet, E.; Giusti, G.; Pique, D.

    2017-06-01

    The different steps of the fabrication of epitaxial AlN films (0.5-20 μm) by high temperature chemical vapor deposition called also HVPE (Hydride Vapor Phase Epitaxy) are reviewed (i) by thermodynamic modeling to analyze reactions in the chlorination chamber, (ii) by multicomponent heat and mass transport for a better knowledge of actual supersaturation of gas species above the substrate, (iii) by simple mechanical modeling to analyze the different source of stress during growth and (iv) by level set methods to represent the interface evolution at the micrometric level on patterned substrates. The evaluation of thin films is discussed in the light of modeling results. The joint use of the different modeling approaches allowed the quantification, for a 2″ substrate, of (i) the optimum temperature for the chlorination chamber (500 °C) to avoid AlCl specie formation, (ii) the transport of the main species AlCl3 diluted in NH3 and H2 and (iii) the actual supersaturation at the growth interface on 2D surfaces or 3D patterned surfaces to promote lateral epitaxial overgrowth and improve crystalline quality. Finally, the upscaling from 2″ to 4″ substrates is computed and validated.

  1. Influence of growth temperature on formation of continuous Ag thin film on ZnO surface by ultra-high vacuum deposition

    International Nuclear Information System (INIS)

    Zhang, T C; Mei, Z X; Guo, Y; Xue, Q K; Du, X L

    2009-01-01

    Growth of an Ag film on a ZnO (0 0 0 1) surface by ultra-high vacuum deposition has been investigated by field emission scanning electron microscopy. It is revealed that the growth temperature has a considerable effect on the formation of a continuous Ag thin film on a ZnO surface. At room temperature or above, the formation of continuous Ag films with small thickness was found to be difficult due to an upstepping mechanism, whereas a continuous Ag film as thin as 30 nm was achieved at 140 K, resulting from the reduced migration length of silver atoms and the increased saturated island density at low temperature. Coalescence between the islands occurred and predominated over upstepping during subsequent deposition, which is favourable for the formation of a continuous Ag film with a smaller thickness.

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

    Science.gov (United States)

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

    2015-01-01

    Composite "wet" alginate films were manufactured from alginate-carbohydrate solutions containing 5% alginate and 0.25% pectin, carrageenan (kappa or iota), potato starch (modified or unmodified), gellan gum, or cellulose (extracted or commercial). The "wet" alginate films were used as a model to understand co-extruded alginate sausage casings that are currently being used by several sausage manufacturers. The mechanical, optical, and microstructural properties of the calcium cross-linked composite films were explored. In addition, the water holding capacity and textural profile analysis properties of the alginate-carbohydrate gels were studied. The results indicate that the mechanical properties of "wet" alginate films/casings can be modified by adding various carbohydrates to them. Alginate films with pectin, carrageenan, and modified potato starch had significantly (P < 0.05) greater elongation values than pure alginate films. The alginate-pectin films also had greater (P < 0.05) tensile strengths than the pure alginate films. Alginate films with extracted cellulose, commercial cellulose, and modified potato starch had lower (P < 0.05) puncture force, distance, and work values than the alginate control films. Transmission electron microscopy images showed a very uniform alginate network in the control films. Several large cellulose fibers were visible in the films with extracted cellulose, while the cellulose fibers in the films with commercial cellulose were difficult to distinguish. Despite these apparent differences in cellulose fiber length, the 2 cellulose films had similar puncture and tensile properties. © 2014 Institute of Food Technologists®

  3. Fabrication and mechanical characterization of biodegradable and synthetic polymeric films: Effect of gamma radiation

    International Nuclear Information System (INIS)

    Akter, Nousin; Khan, Ruhul A.; Salmieri, Stephane; Sharmin, Nusrat; Dussault, Dominic; Lacroix, Monique

    2012-01-01

    Chitosan (1 wt%, in 2% aqueous acetic acid solution) and starch (1 wt%, in deionised water) were dissolved and mixed in different proportions (20–80 wt% chitosan) then films were prepared by casting. Tensile strength and elongation at break of the 50% chitosan containing starch-based films were found to be 47 MPa and 16%, respectively. It was revealed that with the increase of chitosan in starch, the values of TS improved significantly. Monomer, 2-butane diol-diacrylate (BDDA) was added into the film forming solutions (50% starch-based), then casted films. The BDDA containing films were irradiated under gamma radiation (5–25 kGy) and it was found that strength of the films improved significantly. On the other hand, synthetic petroleum-based polymeric films (polycaprolactone, polyethylene and polypropylene) were prepared by compression moulding. Mechanical and barrier properties of the films were evaluated. The gamma irradiated (25 kGy) films showed higher strength and better barrier properties. - Highlights: ► Chitosan and starch-based biodegradable films were prepared by casting. ► With the increase of chitosan in starch, the strength of the films improved significantly. ► Monomer, 2-Butane diol-diacrylate was grafted with the films by gamma radiation. ► Mechanical properties of synthetic polymeric films improved by gamma radiation. ► The irradiated polymer films showed better water vapor barrier properties.

  4. Epitaxial growth of solution deposited Bi2Sr2CaCu2Ox films

    NARCIS (Netherlands)

    Gobel, OF; Du, [No Value; Hibma, T; von Lampe, [No Value; Steiner, U

    The epitaxial growth of Bi2Sr2CaCu2Ox (Bi2212) high temperature superconducting thin films was studied. The films were solution-deposited from a polymer-containing precursor onto SrTiO3 (001) substrates. Bi2212 formed an epitaxial phase with the c-axis parallel to the substrate normal and an in-lane

  5. Pulsed DC sputtered DLC based nanocomposite films : controlling growth dynamics, microstructure and frictional properties

    NARCIS (Netherlands)

    Shaha, K.P.; Pei, Y.T.; Chen, C.Q.; Hosson, J.Th.M. de

    Surface smoothness of diamond-like carbon based thin films becomes a crucial property for developing nearly frictionless protective coatings. Surface roughness and the dynamic growth behaviour of TiC/a-C nanocomposite films, deposited by non-reactive pulsed DC (p-DC) sputtering of graphite targets,

  6. Mocvd Growth of Group-III Nitrides on Silicon Carbide: From Thin Films to Atomically Thin Layers

    Science.gov (United States)

    Al Balushi, Zakaria Y.

    Group-III nitride semiconductors (AlN, GaN, InN and their alloys) are considered one of the most important class of materials for electronic and optoelectronic devices. This is not limited to the blue light-emitting diode (LED) used for efficient solid-state lighting, but other applications as well, such as solar cells, radar and a variety of high frequency power electronics, which are all prime examples of the technological importance of nitride based wide bandgap semiconductors in our daily lives. The goal of this dissertation work was to explore and establish new growth schemes to improve the structural and optical properties of thick to atomically thin films of group-III nitrides grown by metalorganic chemical vapor deposition (MOCVD) on SiC substrates for future novel devices. The first research focus of this dissertation was on the growth of indium gallium nitride (InGaN). This wide bandgap semiconductor has attracted much research attention as an active layer in LEDs and recently as an absorber material for solar cells. InGaN has superior material properties for solar cells due to its wavelength absorption tunability that nearly covers the entire solar spectrum. This can be achieved by controlling the indium content in thick grown material. Thick InGaN films are also of interest as strain reducing based layers for deep-green and red light emitters. The growth of thick films of InGaN is, however, hindered by several combined problems. This includes poor incorporation of indium in alloys, high density of structural and morphological defects, as well as challenges associated with the segregation of indium in thick films. Overcoming some of these material challenges is essential in order integrate thick InGaN films into future optoelectronics. Therefore, this dissertation research investigated the growth mechanism of InGaN layers grown in the N-polar direction by MOCVD as a route to improve the structural and optical properties of thick InGaN films. The growth

  7. Factors affecting the growth of the Malawian film industry | Magalasi ...

    African Journals Online (AJOL)

    Journal of Development and Communication Studies ... This article attempts to ask some of the most basic questions about the practice of film making in Malawi on who, what, and how films have been created, tracing the history of cinema from the British Colonial practice, through Kamuzu Banda's reign to the present.

  8. Deformation-induced grain growth and twinning in nanocrystalline palladium thin films

    Directory of Open Access Journals (Sweden)

    Aaron Kobler

    2013-09-01

    Full Text Available The microstructure and mechanical properties of nanocrystalline Pd films prepared by magnetron sputtering have been investigated as a function of strain. The films were deposited onto polyimide substrates and tested in tensile mode. In order to follow the deformation processes in the material, several samples were strained to defined straining states, up to a maximum engineering strain of 10%, and prepared for post-mortem analysis. The nanocrystalline structure was investigated by quantitative automated crystal orientation mapping (ACOM in a transmission electron microscope (TEM, identifying grain growth and twinning/detwinning resulting from dislocation activity as two of the mechanisms contributing to the macroscopic deformation. Depending on the initial twin density, the samples behaved differently. For low initial twin densities, an increasing twin density was found during straining. On the other hand, starting from a higher twin density, the twins were depleted with increasing strain. The findings from ACOM-TEM were confirmed by results from molecular dynamics (MD simulations and from conventional and in-situ synchrotron X-ray diffraction (CXRD, SXRD experiments.

  9. A Study on the Thermodynamics of Grain Growth in R.F. Magnetron Sputtered NiO Thin Films

    Directory of Open Access Journals (Sweden)

    I. Dhanya

    2013-01-01

    Full Text Available Postdeposition annealing of thin nickel films synthesized using R.F. magnetron sputtering technique is carried in this study. The XRD analysis indicates that annealing of the nickel films leads to the formation of nickel oxide with a preferential growth along (200 plane. The oxidation mechanism is observed with a phase transformation and results in polycrystalline NiO films. The surface morphology of the thin films was investigated by scanning electron microscopy (SEM and atomic force microscopy (AFM as a function of annealing temperature. The studies indicate the formation of well-defined grain boundaries due to agglomeration of nanocrystallites. The films annealed in the range 573–773 K are found to be porous. The optical transmission spectra of the films annealed at 773 K exhibit interference effects for photon energies below the fundamental absorption edge. The optical studies indicate the existence of direct interband transition across a bandgap of 3.7 eV in confirmation with earlier band structure calculations.

  10. Gas Permeation, Mechanical Behavior and Cytocompatibility of Ultrathin Pure and Doped Diamond-Like Carbon and Silicon Oxide Films

    Directory of Open Access Journals (Sweden)

    Juergen M. Lackner

    2013-12-01

    Full Text Available Protective ultra-thin barrier films gather increasing economic interest for controlling permeation and diffusion from the biological surrounding in implanted sensor and electronic devices in future medicine. Thus, the aim of this work was a benchmarking of the mechanical oxygen permeation barrier, cytocompatibility, and microbiological properties of inorganic ~25 nm thin films, deposited by vacuum deposition techniques on 50 µm thin polyetheretherketone (PEEK foils. Plasma-activated chemical vapor deposition (direct deposition from an ion source was applied to deposit pure and nitrogen doped diamond-like carbon films, while physical vapor deposition (magnetron sputtering in pulsed DC mode was used for the formation of silicon as well as titanium doped diamond-like carbon films. Silicon oxide films were deposited by radio frequency magnetron sputtering. The results indicate a strong influence of nanoporosity on the oxygen transmission rate for all coating types, while the low content of microporosity (particulates, etc. is shown to be of lesser importance. Due to the low thickness of the foil substrates, being easily bent, the toughness as a measure of tendency to film fracture together with the elasticity index of the thin films influence the oxygen barrier. All investigated coatings are non-pyrogenic, cause no cytotoxic effects and do not influence bacterial growth.

  11. Effect of corn-zein coating on the mechanical properties of polypropylene packaging films

    OpenAIRE

    Tıhmınlıoğlu, Funda; Atik, İsa Doğan; Özen, Banu

    2011-01-01

    In this study, a novel film structure of corn zein coated on polypropylene (PP) synthetic films for food packaging applications was developed, and the mechanical properties of the resulting coated film, as affected by the coating formulation, were investigated. Composite structures of PP films coated with corn zein were obtained through a simple solvent casting method. Different amounts of corn zein (5 and 15%) were dissolved in 70 and 95% aqueous ethanol solution at 50 C. Solutions of corn z...

  12. Structure and Growth Control of Organic–Inorganic Halide Perovskites for Optoelectronics: From Polycrystalline Films to Single Crystals

    Science.gov (United States)

    Chen, Yani; He, Minhong; Peng, Jiajun; Sun, Yong

    2016-01-01

    Recently, organic–inorganic halide perovskites have sparked tremendous research interest because of their ground‐breaking photovoltaic performance. The crystallization process and crystal shape of perovskites have striking impacts on their optoelectronic properties. Polycrystalline films and single crystals are two main forms of perovskites. Currently, perovskite thin films have been under intensive investigation while studies of perovskite single crystals are just in their infancy. This review article is concentrated upon the control of perovskite structures and growth, which are intimately correlated for improvements of not only solar cells but also light‐emitting diodes, lasers, and photodetectors. We begin with the survey of the film formation process of perovskites including deposition methods and morphological optimization avenues. Strategies such as the use of additives, thermal annealing, solvent annealing, atmospheric control, and solvent engineering have been successfully employed to yield high‐quality perovskite films. Next, we turn to summarize the shape evolution of perovskites single crystals from three‐dimensional large sized single crystals, two‐dimensional nanoplates, one‐dimensional nanowires, to zero‐dimensional quantum dots. Siginificant functions of perovskites single crystals are highlighted, which benefit fundamental studies of intrinsic photophysics. Then, the growth mechanisms of the previously mentioned perovskite crystals are unveiled. Lastly, perspectives for structure and growth control of perovskites are outlined towards high‐performance (opto)electronic devices. PMID:27812463

  13. Structure and Growth Control of Organic-Inorganic Halide Perovskites for Optoelectronics: From Polycrystalline Films to Single Crystals.

    Science.gov (United States)

    Chen, Yani; He, Minhong; Peng, Jiajun; Sun, Yong; Liang, Ziqi

    2016-04-01

    Recently, organic-inorganic halide perovskites have sparked tremendous research interest because of their ground-breaking photovoltaic performance. The crystallization process and crystal shape of perovskites have striking impacts on their optoelectronic properties. Polycrystalline films and single crystals are two main forms of perovskites. Currently, perovskite thin films have been under intensive investigation while studies of perovskite single crystals are just in their infancy. This review article is concentrated upon the control of perovskite structures and growth, which are intimately correlated for improvements of not only solar cells but also light-emitting diodes, lasers, and photodetectors. We begin with the survey of the film formation process of perovskites including deposition methods and morphological optimization avenues. Strategies such as the use of additives, thermal annealing, solvent annealing, atmospheric control, and solvent engineering have been successfully employed to yield high-quality perovskite films. Next, we turn to summarize the shape evolution of perovskites single crystals from three-dimensional large sized single crystals, two-dimensional nanoplates, one-dimensional nanowires, to zero-dimensional quantum dots. Siginificant functions of perovskites single crystals are highlighted, which benefit fundamental studies of intrinsic photophysics. Then, the growth mechanisms of the previously mentioned perovskite crystals are unveiled. Lastly, perspectives for structure and growth control of perovskites are outlined towards high-performance (opto)electronic devices.

  14. Fundamental studies of growth mechanisms in physical vapour deposition of aluminium

    CERN Document Server

    Knorr, N J

    2000-01-01

    temperature could be independently controlled due to the low deposition rate of the aluminium. The depositions were performed in a UHV environment to ensure that film growth was not mediated by contamination. The ion energy range used was 10-75eV and the substrate temperature varied from -100 deg C to 200 deg C. The depositions were onto silicon (100) with a native oxide surface, except for a set of depositions which were performed on to silicon with the native oxide surface removed. The cleanliness of the depositions was verified using in-situ XPS analysis and after deposition the structure of the aluminium films was inferred from measurements using SEM, TEM, AFM XRD and Nano-indendation. This information allowed the mechanisms of growth of the aluminium films to be investigated. In addition to the extensive array of IBDR depositions a series of aluminium films were deposited using evaporation and sputtering. These films were grown at substrate temperatures between room temperate and 200 deg C. The use of ev...

  15. Hybrid liquid phase epitaxy processes for YBa{sub 2}Cu{sub 3}O{sub 7} film growth

    Energy Technology Data Exchange (ETDEWEB)

    Kursumovic, A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Tomov, R I [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Huehne, R [Institut fuer Festkoerper-und Werkstoffforschung, Helmholtzstrasse 20, 01069 Dresden (Germany); MacManus-Driscoll, J L [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Glowacki, B A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Evetts, J E [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

    2004-10-01

    A number of liquid phase epitaxy (LPE) related growth methods have been investigated. These hybrid-LPE processes enable high rate 'liquid assisted' growth of epitaxial YBa{sub 2}Cu{sub 3}O{sub 7} films without the many disadvantages of classical LPE. Growth occurs by diffusive transport of Y through a thin liquid flux layer. This layer may be pre-deposited onto the substrate by various means including vacuum and non-vacuum techniques, or deposited at the growth temperature. The composition of the liquid layer is maintained during film growth by feeding YBa{sub 2}Cu{sub 3}O{sub 7}, or the separate components, either from the vapour or by a powder route. Growth rates up to 10 nm s{sup -1} have been demonstrated. Deposition of c-axis oriented epitaxial YBa{sub 2}Cu{sub 3}O{sub 7} is reported on both seeded and non-seeded substrates; the process is tolerant of a high substrate mismatch. Films 1-2 {mu}m thick with T{sub c} {approx} 90K and a critical current density J{sub c}> 2 MA cm{sup -2} have been grown on a range of single crystal substrates as well as on buffered textured metallic tapes. The mechanism of nucleation and growth from a thin liquid layer is described within the general theoretical framework of crystal growth. Particular features of the growth are the short time constant for equilibration of transients in the deposition conditions, the wide range of relative supersaturation spanned by the process, and dominance of interface kinetic effects compared to volume diffusion in the liquid flux.

  16. Big-data reflection high energy electron diffraction analysis for understanding epitaxial film growth processes.

    Science.gov (United States)

    Vasudevan, Rama K; Tselev, Alexander; Baddorf, Arthur P; Kalinin, Sergei V

    2014-10-28

    Reflection high energy electron diffraction (RHEED) has by now become a standard tool for in situ monitoring of film growth by pulsed laser deposition and molecular beam epitaxy. Yet despite the widespread adoption and wealth of information in RHEED images, most applications are limited to observing intensity oscillations of the specular spot, and much additional information on growth is discarded. With ease of data acquisition and increased computation speeds, statistical methods to rapidly mine the data set are now feasible. Here, we develop such an approach to the analysis of the fundamental growth processes through multivariate statistical analysis of a RHEED image sequence. This approach is illustrated for growth of La(x)Ca(1-x)MnO(3) films grown on etched (001) SrTiO(3) substrates, but is universal. The multivariate methods including principal component analysis and k-means clustering provide insight into the relevant behaviors, the timing and nature of a disordered to ordered growth change, and highlight statistically significant patterns. Fourier analysis yields the harmonic components of the signal and allows separation of the relevant components and baselines, isolating the asymmetric nature of the step density function and the transmission spots from the imperfect layer-by-layer (LBL) growth. These studies show the promise of big data approaches to obtaining more insight into film properties during and after epitaxial film growth. Furthermore, these studies open the pathway to use forward prediction methods to potentially allow significantly more control over growth process and hence final film quality.

  17. Growth of (100)-highly textured BaBiO{sub 3} thin films on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ferreyra, C. [GIyA and INN, CNEA, Av. Gral Paz 1499, 1650 San Martín, Buenos Aires (Argentina); Departamento de Física, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 1, Ciudad Universitaria, Buenos Aires (Argentina); Marchini, F. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Departamento de Química Inorgánica, Analítica y Química-Física, INQUIMAE-CONICET, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, Buenos Aires (Argentina); Granell, P. [INTI, CMNB, Av. Gral Paz 5445, B1650KNA San Martín, Buenos Aires (Argentina); Golmar, F. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); INTI, CMNB, Av. Gral Paz 5445, B1650KNA San Martín, Buenos Aires (Argentina); Escuela de Ciencia y Tecnología, UNSAM, Campus Miguelete, 1650 San Martín, Buenos Aires (Argentina); Albornoz, C. [GIyA and INN, CNEA, Av. Gral Paz 1499, 1650 San Martín, Buenos Aires (Argentina); and others

    2016-08-01

    We report on the growth and characterization of non-epitaxial but (100)-highly textured BaBiO{sub 3} thin films on silicon substrates. We have found the deposition conditions that optimize the texture, and show that the textured growth is favoured by the formation of a BaO layer at the first growth stages. X-ray diffraction Φ-scans, together with the observation that the same textured growth is found on films grown on Pt and SiO{sub 2} buffered Si, demonstrate the absence of epitaxy. Finally, we have shown that our (100)-oriented BaBiO{sub 3} films can be used as suitable buffers for the growth of textured heterostructures on silicon, which could facilitate the integration of potential devices with standard electronics. - Highlights: • BaBiO{sub 3} thin films were grown on Si substrates and characterized. • Films prepared using optimized conditions are highly textured in the (100) direction. • The absence of in-plane texture was demonstrated by X-ray diffraction. • Our films are suitable buffers for the growth of (100)-textured oxide heterostructures.

  18. Morphological, mechanical, barrier and properties of films based on acetylated starch and cellulose from barley.

    Science.gov (United States)

    El Halal, Shanise Lisie Mello; Colussi, Rosana; Biduski, Bárbara; Evangelho, Jarine Amaral do; Bruni, Graziella Pinheiro; Antunes, Mariana Dias; Dias, Alvaro Renato Guerra; Zavareze, Elessandra da Rosa

    2017-01-01

    Biodegradable films of native or acetylated starches with different concentrations of cellulose fibers (0%, 10% and 20%) were prepared. The films were characterized by morphological, mechanical, barrier, and thermal properties. The tensile strength of the acetylated starch film was lower than those of the native starch film, without fibers. The addition of fibers increased the tensile strength and decreased the elongation and the moisture of native and acetylated starches films. The acetylated starch film showed higher water solubility when compared to native starch film. The addition of cellulose fibers reduced the water solubility of the acetylated starch film. The films reinforced with cellulose fiber exhibited a higher initial decomposition temperature and thermal stability. The mechanical, barrier, solubility, and thermal properties are factors which direct the type of the film application in packaging for food products. The films elaborated with acetylated starches of low degree of substitution were not effective in a reduction of the water vapor permeability. The addition of the cellulose fiber in acetylated and native starches films can contribute to the development of more resistant films to be applied in food systems that need to maintain their integrity. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  19. Growth and thermoelectric properties of FeSb2 films produced by pulsed laser deposition

    DEFF Research Database (Denmark)

    Sun, Ye; Canulescu, Stela; Sun, Peijie

    2011-01-01

    Thermoelectric FeSb2 films were produced by pulsed laser deposition on silica substrates in a low-pressure Ar environment. The growth conditions for near phase-pure FeSb2 films were confirmed to be optimized at a substrate temperature of 425°C, an Ar pressure of 2 Pa, and deposition time of 3 h...... by ablating specifically prepared compound targets made of Fe and Sb powders in atomic ratio of 1:4. The thermoelectric transport properties of FeSb2 films were investigated. Pulsed laser deposition was demonstrated as a method for production of good-quality FeSb2 films....

  20. Pulsed laser deposition: A viable route for the growth of aluminum antimonide film

    Science.gov (United States)

    Das, S.; Ghosh, B.; Hussain, S.; Bhar, R.; Pal, A. K.

    2015-06-01

    Aluminum antimonide films (AlSb) were successfully deposited on glass substrates by ablating an aluminum antimonide target using pulsed Nd-YAG laser. Films deposited at substrate temperatures 773 K and above showed zinc blende structure. Increase in substrate temperature culminated in grain growth in the films. Photoluminescence studies indicated a strong peak 725 nm ( 1.71 eV) and 803 nm ( 1.55 eV). Films deposited at higher deposition temperatures indicated lower residual strain. Characteristic Raman peaks for AlSb at 151 cm-1 followed by two peaks located at 71 cm-1 and 116 cm-1 were also observed.

  1. Growth and characterization of MnAu{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, S.F., E-mail: shufan.cheng.ctr@nrl.navy.mil; Bussmann, K.M.

    2017-01-01

    MnAu{sub 2} films ranging from 60 to 200 nm thickness are deposited by co-sputtering from elemental targets. X-ray diffraction confirmed these films to be nearly single phase with tetragonal lattice parameters of a=0.336 nm and c=0.872 nm that compare well to the bulk values of a=0.336 nm and c=0.876 nm. The density of the films is analyzed using x-ray reflectivity to be 14.95 g/cm{sup 3} and within experimental error of previously determined value of 15.00 g/cm{sup 3}. The films grown on c-plane sapphire, (100)MgO and (100)MgF{sub 2} are randomly oriented polycrystalline, while the films grown on a-plane sapphire, (111)MgO and (111)Si/(0001)AlN showed that the (110) plane is parallel to the film plane and there are three sets of domains in equal amount differing by 60° in-plane rotation. Magnetic order is found to become paramagnetic near 360 K which is in close proximity to the bulk value. There are deviations in the slope of hysteresis loops observed at 10 K around 10 kOe that indicate complex magnetic switching. - Highlights: • Single phase MnAu{sub 2} films were prepared with full density. • The lattice parameters are close to its bulk values. • The films on a-Al{sub 2}O{sub 3}, (111) MgO and (0001)AlN have the (110) in the film plane. • There are three sets of domains in equal amount differed by 60° in-plane rotation. • The magnetic ordering occurs near the bulk value of 363 K.

  2. THE DEVELOPMENT OF THE MECHANICS OF FILM RATING.

    Science.gov (United States)

    HANDY, RICKI; AND OTHERS

    A TRANSCRIPTION WAS MADE OF A GROUP DISCUSSION DEALING WITH THE DEVELOPMENT OF RATING SCALES AND THE TECHNIQUES OF FILM RATING AND OF USE OF THE EQUIPMENT. THE AMIDON-FLANDERS INTERACTION ANALYSIS SCALE WAS USED AS THE BASIS FOR THE DEVELOPMENT OF THE FILM ANALYSIS OF INTERACTION RECORD (FAIR). DISCUSSIONS DEALT WITH SUCH PROBLEMS OF FILM RATING…

  3. Mechanism for selective growth in electrical steel

    Science.gov (United States)

    Oh, Eun Jee; Heo, Nam Hoe; Kwon, Se Kyun; Koo, Yang Mo

    2018-01-01

    Through the competitive selective growth process between {100}, {110}, and {111} grains during final annealing which is governed by the primary grain size and the surface segregation concentration of sulfur, the sharp {110} annealing texture can be developed in a C-and Al-free Fe-3%Si-0.1%Mn electrical steel. Generally, the selective growth of the {110} grains occurs actively under the low surface segregation concentration of sulfur. In spite of the surface energy disadvantage, the selective growth of a {hkl} grain can however occur, if the {hkl} grain size is larger than the critical grain size linearly proportional to the strip thickness.

  4. Electrochemical growth of synthetic melanin thin films by constant potential methods

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Gyun; Nam, Hye Jin; Ahn, Hyeon Ju [Department of Chemistry, School of Chemical Materials Science, Institute of Basic Sciences, Sungkyunkwan Advanced Institute of NanoTechnology (SAINT), Sungkyunkwan University, Chunchun-dong, Gyunggi-do, Suwon 440-746 (Korea, Republic of); Jung, Duk-Young, E-mail: dyjung@skku.ed [Department of Chemistry, School of Chemical Materials Science, Institute of Basic Sciences, Sungkyunkwan Advanced Institute of NanoTechnology (SAINT), Sungkyunkwan University, Chunchun-dong, Gyunggi-do, Suwon 440-746 (Korea, Republic of)

    2011-02-28

    Polymerized melanin thin films were electrochemically synthesized in a 5,6-dihydroxyindole precursor solution on indium tin oxide (ITO) substrates using the cyclic voltammetry and constant potential methods. Tris(hydroxymethyl)aminomethane (THAM) and phosphate buffer solutions were applied to prepare the films that were well deposited to the ITO substrates. The films that were synthesized in the THAM buffer solution exhibited a faster growth rate and better adhesion to the ITO electrodes than the films in the phosphate buffer. The film thickness linearly increased at the growth rate of 0.8 nm/s as the deposition time and number of cycles increased. Two electrochemical conditions produced similar thicknesses as well as physical properties in each buffer solution. However, the constant potential method demonstrated that this provides the synthetic advantages of faster deposition and less consumption of electric charge compared to the cyclic voltammetry route.

  5. Growth and characterization of α and β-phase tungsten films on various substrates

    International Nuclear Information System (INIS)

    Lee, Jeong-Seop; Cho, Jaehun; You, Chun-Yeol

    2016-01-01

    The growth conditions of tungsten thin films were investigated using various substrates including Si, Si/SiO 2 , GaAs, MgO, and Al 2 O 3 , and recipes were discovered for the optimal growth conditions of thick metastable β-phase tungsten films on Si, GaAs, and Al 2 O 3 substrates, which is an important material in spin orbit torque studies. For the Si/SiO 2 substrate, the crystal phase of the tungsten films was different depending upon the tungsten film thickness, and the transport properties were found to dramatically change with the thickness owing to a change in phase from the α + β phase to the α-phase. It is shown that the crystal phase changes are associated with residual stress in the tungsten films and that the resistivity is closely related to the grain sizes

  6. Mechanical properties of ultra thin metallic films revealed by synchrotron techniques

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Patric Alfons

    2007-07-20

    A prerequisite for the study of the scaling behavior of mechanical properties of ultra thin films is a suitable testing technique. Therefore synchrotron-based in situ testing techniques were developed and optimized in order to characterize the stress evolution in ultra thin metallic films on compliant polymer substrates during isothermal tensile tests. Experimental procedures for polycrystalline as well as single crystalline films were established. These techniques were used to systematically investigate the influence of microstructure, film thickness (20 to 1000 nm) and temperature (-150 to 200 C) on the mechanical properties. Passivated and unpassivated Au and Cu films as well as single crystalline Au films on polyimide substrates were tested. Special care was also dedicated to the microstructural characterization of the samples which was very important for the correct interpretation of the results of the mechanical tests. Down to a film thickness of about 100 to 200 nm the yield strength increased for all film systems (passivated and unpassivated) and microstructures (polycrystalline and singlecrystalline). The influence of different interfaces was smaller than expected. This could be explained by a dislocation source model based on the nucleation of perfect dislocations. For polycrystalline films the film thickness as well as the grain size distribution had to be considered. For smaller film thicknesses the increase in flow stress was weaker and the deformation behavior changed because the nucleation of perfect dislocations became unfavorable. Instead, the film materials used alternative mechanisms to relieve the high stresses. For regular and homogeneous deformation the total strain was accommodated by the nucleation and motion of partial dislocations. If the deformation was localized due to initial cracks in a brittle interlayer or local delamination, dislocation plasticity was not effective enough to relieve the stress concentration and the films showed

  7. Growth and Analysis of Highly Oriented (11n) BCSCO Films for Device Research

    Science.gov (United States)

    Raina, K. K.; Pandey, R. K.

    1995-01-01

    Films of BCSCO superconductor of the type Bi2CaSr2Cu2O(x), have been grown by liquid phase epitaxy method (LPE), using a partially closed growth chamber. The films were grown on (001) and (110) NdGaO3 substrates by slow cooling process in an optimized temperature range below the peritectic melting point (880 C) of Bi2CaSr2Cu2O8. Optimization of parameters, such as seed rotation, soak of initial growth temperature and growth period results in the formation of 2122 phase BCSCO films. The films grown at rotation rates of less than 30 and more than 70 rpm are observed to be associated with the second phase of Sr-Ca-Cu-O system. Higher growth temperatures (greater than 860 C) also encourage to the formation of this phase. XRD measurements show that the films grown on (110) NdGaO3 have a preferred (11n)-orientation. It is pertinent to mention here that in our earlier results published elsewhere we obtained c-axis oriented Bi2CaSr2Cu2O8 phase films on (001) NdGaO3 substrate. Critical current density is found to be higher for the films grown on (110) than (001) NdGaO3 substrate orientation. The best values, zero resistance (T(sab co)) and critical current density obtained are 87 K and 10(exp 5) A/sq cm respectively.

  8. Structural, mechanical, and magnetic properties of GaFe3N thin films

    International Nuclear Information System (INIS)

    Junaid, Muhammad; Music, Denis; Hans, Marcus; Schneider, Jochen M.; Scholz, Tanja; Dronskowski, Richard; Primetzhofer, Daniel

    2016-01-01

    Using the density-functional theory, the structural, mechanical, and magnetic properties were investigated for different GaFe 3 N configurations: ferromagnetic, ferrimagnetic, paramagnetic, and nonmagnetic. Ferrimagnetic and high-spin ferromagnetic states exhibit the lowest energy and are the competing ground states as the total energy difference is 0.3 meV/atom only. All theoretically predicted values could be fully confirmed by experiments. For this, the authors synthesized phase pure, homogeneous, and continuous GaFe 3 N films by combinatorial reactive direct current magnetron sputtering. Despite the low melting point of gallium, the authors succeeded in the growth of GaFe 3 N films at a temperature of 500 °C. Those thin films exhibit a lattice parameter of 3.794 Å and an elastic modulus of 226 ± 20 GPa. Magnetic susceptibility measurements evidence a magnetic phase transitions at 8.0 ± 0.1 K. The nearly saturated magnetic moment at ±5 T is about 1.6 μB/Fe and is close to the theoretically determined magnetic moment for a ferrimagnetic ordering (1.72 μB/Fe).

  9. Structural and mechanical properties of ZrSiN thin films prepared by reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, F.G.R.; Conceicao, A.G.S.; Vitoria, E.R.; Carvalho, R.G.; Tentardini, E.K. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil); Hübler, R. [Pontificia Universidade Catolica do Rio Grande do Sul (PUC-RS), Porto Alegre, RS (Brazil); Soares, G., E-mail: flaviogus@hotmail.com, E-mail: etentardini@gmail.com, E-mail: hubler@pucrs.br, E-mail: gabriel.soares@ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

    2014-07-01

    Zirconium silicon nitride (ZrSiN) thin films were deposited by reactive magnetron sputtering in order to verify the silicon influence on coating morphology and mechanical properties. The Si/(Zr+Si) ratio was adjusted between 0 to 14.5% just modifying the power applied on the silicon target. Only peaks associated to ZrN crystalline structure were observed in XRD analysis, since Si{sub 3}N{sub 4} phase was amorphous. All samples have (111) preferred orientation, but there is a peak intensity reduction and a broadening increase for the sample with the highest Si/(Zr+Si) ratio (14.5%), demonstrating a considerable loss of crystallinity or grain size reduction (about 8 nm calculated by Scherrer). It was also observed that the texture coefficient for (200) increases with silicon addition. Chemical composition and thickness of the coatings were determined by RBS analysis. No significant changes in nano hardness with increasing Si content were found. The thin film morphology observed by SEM presents columnar and non columnar characteristics. The set of results suggests that Si addition is restricting the columnar growth of ZrN thin films. This conclusion is justified by the fact that Si contributes to increase the ZrN grains nucleation during the sputtering process. (author)

  10. Structural and mechanical properties of ZrSiN thin films prepared by reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Freitas, F.G.R.; Conceicao, A.G.S.; Vitoria, E.R.; Carvalho, R.G.; Tentardini, E.K.; Hübler, R.; Soares, G.

    2014-01-01

    Zirconium silicon nitride (ZrSiN) thin films were deposited by reactive magnetron sputtering in order to verify the silicon influence on coating morphology and mechanical properties. The Si/(Zr+Si) ratio was adjusted between 0 to 14.5% just modifying the power applied on the silicon target. Only peaks associated to ZrN crystalline structure were observed in XRD analysis, since Si 3 N 4 phase was amorphous. All samples have (111) preferred orientation, but there is a peak intensity reduction and a broadening increase for the sample with the highest Si/(Zr+Si) ratio (14.5%), demonstrating a considerable loss of crystallinity or grain size reduction (about 8 nm calculated by Scherrer). It was also observed that the texture coefficient for (200) increases with silicon addition. Chemical composition and thickness of the coatings were determined by RBS analysis. No significant changes in nano hardness with increasing Si content were found. The thin film morphology observed by SEM presents columnar and non columnar characteristics. The set of results suggests that Si addition is restricting the columnar growth of ZrN thin films. This conclusion is justified by the fact that Si contributes to increase the ZrN grains nucleation during the sputtering process. (author)

  11. Structural, mechanical, and magnetic properties of GaFe{sub 3}N thin films

    Energy Technology Data Exchange (ETDEWEB)

    Junaid, Muhammad, E-mail: junaid@mch.rwth-aachen.de; Music, Denis, E-mail: music@mch.rwth-aachen.de; Hans, Marcus; Schneider, Jochen M. [Materials Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Scholz, Tanja; Dronskowski, Richard [Institute of Inorganic Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Primetzhofer, Daniel [Department of Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, S-75120 Uppsala (Sweden)

    2016-07-15

    Using the density-functional theory, the structural, mechanical, and magnetic properties were investigated for different GaFe{sub 3}N configurations: ferromagnetic, ferrimagnetic, paramagnetic, and nonmagnetic. Ferrimagnetic and high-spin ferromagnetic states exhibit the lowest energy and are the competing ground states as the total energy difference is 0.3 meV/atom only. All theoretically predicted values could be fully confirmed by experiments. For this, the authors synthesized phase pure, homogeneous, and continuous GaFe{sub 3}N films by combinatorial reactive direct current magnetron sputtering. Despite the low melting point of gallium, the authors succeeded in the growth of GaFe{sub 3}N films at a temperature of 500 °C. Those thin films exhibit a lattice parameter of 3.794 Å and an elastic modulus of 226 ± 20 GPa. Magnetic susceptibility measurements evidence a magnetic phase transitions at 8.0 ± 0.1 K. The nearly saturated magnetic moment at ±5 T is about 1.6 μB/Fe and is close to the theoretically determined magnetic moment for a ferrimagnetic ordering (1.72 μB/Fe).

  12. Transients in the growth of passive films on high level nuclear waste canisters

    International Nuclear Information System (INIS)

    Urquidi-Macdonald, M.; Macdonald, Digby D.

    2003-01-01

    A new rate law for the growth of anodic passive films on metal surfaces that was recently derived from the Point Defect Model (PDM) is used to predict the transients in current density and film thickness on Alloy C-22 over extended periods of time in an environment (saturated brine) that is postulated to exist in high level nuclear waste repositories. The model recognizes both the growth of the barrier oxide layer into the metal via the generation of oxygen vacancies at the metal/film interface and the dissolution of the barrier layer at the film/solution interface, as well as the current carried by cation interstitials within the Cr 2 O 3 barrier layer. The derived rate law accounts for the existence of a steady state in film thickness as well as for the transients in thickness and film growth current as the potential is stepped in the positive or negative direction from an initial steady state. The predicted transients in film thickness and growth current density for Alloy C-22 in the prototypical HLNW (High Level Nuclear Waste) environment employed demonstrate that the kinetics of dissolution of the barrier oxide layer at the barrier layer/solution interface control the rate of passive film thinning when the corrosion potential is stepped in the negative direction, whereas the kinetics of oxygen vacancy generation at the metal/film interface control the rate of film thickening when the potential is displaced in the positive direction. While the transients are predicted to persist for considerable time, the times are short compared with the design life of the repository and we conclude that the accumulated damage due to general corrosion is readily predicted by using quasi steady-state models. (authors)

  13. Optimizing growth conditions for electroless deposition of Au films ...

    Indian Academy of Sciences (India)

    Unknown

    aurate plating solutions has been carried out at varying concentrations, deposition durations as well as bath temperatures, and the result- ing films were characterized by X-ray diffraction, optical profilometry, atomic force microscopy and ...

  14. Preventing bacterial growth on implanted device with an interfacial metallic film and penetrating X-rays.

    Science.gov (United States)

    An, Jincui; Sun, An; Qiao, Yong; Zhang, Peipei; Su, Ming

    2015-02-01

    Device-related infections have been a big problem for a long time. This paper describes a new method to inhibit bacterial growth on implanted device with tissue-penetrating X-ray radiation, where a thin metallic film deposited on the device is used as a radio-sensitizing film for bacterial inhibition. At a given dose of X-ray, the bacterial viability decreases as the thickness of metal film (bismuth) increases. The bacterial viability decreases with X-ray dose increases. At X-ray dose of 2.5 Gy, 98% of bacteria on 10 nm thick bismuth film are killed; while it is only 25% of bacteria are killed on the bare petri dish. The same dose of X-ray kills 8% fibroblast cells that are within a short distance from bismuth film (4 mm). These results suggest that penetrating X-rays can kill bacteria on bismuth thin film deposited on surface of implant device efficiently.

  15. Solvent-assisted growth of metal phthalocyanine thin films on Au(111)

    Energy Technology Data Exchange (ETDEWEB)

    Tskipuri, Levan; Shao Qian; Reutt-Robey, Janice [Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742-4454 (United States)

    2012-05-15

    Thin films of metal phthalocyanine (MPc) are grown on an Au(111) support with a newly developed aerosol molecular beam deposition source and characterized in situ via ultrahigh vacuum scanning tunneling microscopy. MPcs are delivered to Au(111) in a series of N{sub 2}-entrained microsized solvent droplets of variable surface residence time. Phthalocyanine film registration to the herringbone reconstruction of the Au(111) surface, indicative of thermodynamically favored structure, is observed at submonolayer coverages for aromatic solvents with long residence times. Aerosol-deposited monolayer film structures are noncrystalline with tilted MPc orientations and vacancy nanocavities. Upon annealing, MPc molecules adopt flat-lying orientations with respect to the substrate and vacancies are eliminated. Film morphologies indicate solvation-mediated film nucleation and growth, with less long-range ordering that in vapor-generated films.

  16. Advances in the understanding of crystal growth mechanisms

    CERN Document Server

    Nishinaga, T; Harada, J; Sasaki, A; Takei, H

    1997-01-01

    This book contains the results of a research project entitled Crystal Growth Mechanisms on an Atomic Scale, which was carried out for 3 years by some 72 reseachers. Until recently in Japan, only the technological aspects of crystal growth have been emphasized and attention was paid only to its importance in industry. However the scientific aspects also need to be considered so that the technology of crystal growth can be developed even further. This project therefore aimed at understanding crystal growth and the emphasis was on finding growth mechanisms on an atomic scale.

  17. Epitaxial Growth of V2O3 Thin Films on c-Plane Al2O3 in Reactive Sputtering and Its Transformation to VO2 Films by Post Annealing

    Science.gov (United States)

    Okimura, Kunio; Suzuki, Yasushi

    2011-06-01

    Epitaxial growth of thin vanadium sesquioxide (V2O3) films on c-plane sapphire (c-Al2O3) substrates was achieved with reactive magnetron sputtering under restricted oxygen flow. Even with a film thickness of approximately 12 nm, highly c-axis textured growth of corundum V2O3 was realized because of the smaller mismatch of V2O3 against corundum Al2O3. Post annealing in O2 atmosphere for as-grown V2O3 films caused phase transformation to oxidized crystalline phases. At a moderate annealing temperature of 450 °C, the V2O3 thin films transformed to VO2 films, which show a resistivity change of over three orders of magnitude. The X-ray photoelectron spectroscopy spectra for the annealed VO2 film showed a single charge state of V4+, indicating a homogeneous crystalline structure, in contrast to the inhomogeneous feature with mixed charge states of V in addition to V3+ for as-grown V2O3 film. This method is promising to prepare thin VO2 films with metal-insulator transition in productive reactive sputtering and to examine crystalline phase transformation mechanisms, including phase coexistence.

  18. Initial stages of the growth of barium strontium titanate films on a semi-isolating silicon carbide substrate

    Science.gov (United States)

    Tumarkin, A. V.; Serenkov, I. T.; Sakharov, V. I.; Razumov, S. V.; Odinets, A. A.; Zlygostov, M. V.; Sapego, E. N.; Afrosimov, V. V.

    2017-12-01

    The initial stages of the growth of ferroelectric barium strontium titanate films on single-crystal silicon carbide substrates have been studied for the first time. The choice of a substrate with high thermal conductivity has been due to the possibility of applying these structures in powerful microwave devices. The temperature ranges separating the mechanism of the surface diffusion of deposited atoms from the diffusion via a gaseous phase during the growth of multicomponent films have been determined. The studies show that the mass transfer by means of surface diffusion leads to the formation of small-height nuclei that cover a large area of the substrate, whereas the mass transfer via a gaseous phase leads to the formation of a "columnar" islandtype structure with small percentage of covering the substrate and larger island heights.

  19. Co-depositing Sn controls the growth of Al films as surfactant

    International Nuclear Information System (INIS)

    Barna, P. B.; Kovacs, A.; Misjak, F.; Eisenmenger-Sittner, C.; Bangert, H.; Tomastik, C.

    2002-01-01

    The present study investigates the influence of co-deposited Sn on the atomic processes involved in the structure evolution of vapour-deposited Al films. The films were prepared in HV by thermal evaporation from W sources at 1600 C substrate temperature either on Si wafers covered by a thermally grown oxide or on air cleaved mica. By applying the half-shadow technique, pure and Sn-doped Al films could be deposited simultaneously. The samples were investigated by AFM, scanning AES, X-TEM as well as by X-ray diffraction methods. The grain growth of Al is promoted by Sn in all stages of the film formation. Scanning AES measurements prove the existence of a wetting Sn layer both on the surface of Al islands and on the surface of the continuos Al layer. Excess Sn forms islands on the growth surface. The surface of pure Al layers exhibits grain boundary grooves and bunches of growth steps around terraces, while that of the Sn doped layers is more rounded. The substrate-film interface was covered by a thin Sn layer. AES measurements also prove the presence of Sn on the growth surface of Al films even after termination of Sn addition. Results of these experiments indicate that during co-deposition of Al and Sn the impinging Al atoms penetrate the wetting layer and are incorporated into the already existing Al crystals. A model has been developed for describing the growth of Al crystals in the presence Sn. (Authors)

  20. Hair Growth Promotion Activity and Its Mechanism of Polygonum multiflorum

    OpenAIRE

    Yunfei Li; Mingnuan Han; Pei Lin; Yanran He; Jie Yu; Ronghua Zhao

    2015-01-01

    Polygonum multiflorum Radix (PMR) has long history in hair growth promotion and hair coloring in clinical applications. However, several crucial problems in its clinic usage and mechanisms are still unsolved or lack scientific evidences. In this research, C57BL/6J mice were used to investigate hair growth promotion activity and possible mechanism of PMR and Polygonum multiflorum Radix Preparata (PMRP). Hair growth promotion activities were investigated by hair length, hair covered skin ratio,...

  1. Mechanisms of lubrication and wear of a bonded solid-lubricant film

    Science.gov (United States)

    Fusaro, R. L.

    1980-01-01

    The tribological properties of polyimide-bonded graphite fluoride films were investigated. A pin-on-disk type of testing apparatus was used; in addition to sliding a hemispherically tipped rider, a rider with a 0.95-mm-diameter flat area was slid against the film so that a lower, less variable contact stress could be achieved. Two stages of lubrication occurred: in the first, the film supported the load and the lubricating mechanism consisted of the shear of a thin surface layer between the rider and the bulk of the film. The second occurred after the bonded film had worn to the substrate, and consisted of the shear of very thin lubricant films between the rider and flat plateaus generated on the metallic substrate asperities. The film wear mechanism was strongly dependent on contact stress.

  2. An AFM study of the morphology and local mechanical properties of superconducting YBCO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Soifer, Ya.M.; Verdyan, A.; Azoulay, J.; Kazakevich, M.; Rabkin, E

    2004-02-01

    The morphology of thin superconducting YBCO films deposited on sapphire and on SrTiO{sub 3} was studied with the help of atomic force and scanning electron microscopies. The intrinsic mechanical properties in the flat, particles-free and chemically homogeneous regions of the films were determined with the aid of nanoindenting atomic force microscope. Also the microscopy studies revealed the difference in topography of the films, the nanohardness and Young's modulus of two films were very close to each other. For the indents shallower than 0.2 of the film thickness the Young's modulus and hardness of the films on two different substrates converged to the values of 210 and 8.5 GPa, respectively. The possible deformation mechanisms determining the localized deformation of intrinsically brittle ceramic films are discussed.

  3. Mechanical, barrier and morphological properties of starch nanocrystals-reinforced pea starch films.

    Science.gov (United States)

    Li, Xiaojing; Qiu, Chao; Ji, Na; Sun, Cuixia; Xiong, Liu; Sun, Qingjie

    2015-05-05

    To characterize the pea starch films reinforced with waxy maize starch nanocrystals, the mechanical, water vapor barrier and morphological properties of the composite films were investigated. The addition of starch nanocrystals increased the tensile strength of the composite films, and the value of tensile strength of the composite films was highest when starch nanocrystals content was 5% (w/w). The moisture content (%), water vapor permeability, and water-vapor transmission rate of the composite films significantly decreased as starch nanocrystals content increased. When their starch nanocrystals content was 1-5%, the starch nanocrystals dispersed homogeneously in the composite films, resulting in a relatively smooth and compact film surface and better thermal stability. However, when starch nanocrystals content was more than 7%, the starch nanocrystals began to aggregate, which resulted in the surface of the composite films developing a longitudinal fibrous structure. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Mechanism of manganese (mono and di) telluride thin-film formation and properties

    Science.gov (United States)

    Sharma, Raj Kishore; Singh, Gurmeet; Shul, Yong Gun; Kim, Hansung

    2007-03-01

    Mechanistic studies on the electrocrystallization of manganese telluride (MnTe) thin film are reported using aqueous acidic solution containing MnSO 4 and TeO 2. Tartaric acid was used for the inhibition of hydrated manganese oxide anodic growth at counter electrode. A detailed study on the mechanistic aspect of electrochemical growth of MnTe using cyclic voltametry is carried out. Conditions for electrochemical growth of manganese mono and di telluride thin films have been reported using cyclic voltammetric scans for Mn 2+, Te 4+ and combined Mn 2+ and Te 4+. X-ray diffraction showed the formation of polycrystalline MnTe films with cubic, hexagonal and orthorhombic mixed phases. MnTe film morphology was studied using scanning electron microscope. Susceptibility and electrical characterization supports the anti-ferromagnetic behavior of the as-deposited MnTe thin film.

  5. Two-component spin-coated Ag/CNT composite films based on a silver heterogeneous nucleation mechanism adhesion-enhanced by mechanical interlocking and chemical grafting

    Science.gov (United States)

    Zhang, Yang; Kang, Zhixin; Bessho, Takeshi

    2017-03-01

    In this paper, a new method for the synthesis of silver carbon nanotube (Ag/CNT) composite films as conductive connection units for flexible electronic devices is presented. This method is about a two-component solution process by spin coating with an after-treatment annealing process. In this method, multi-walled carbon nanotubes (MWCNTs) act as the core of silver heterogeneous nucleation, which can be observed and analyzed by a field-emission scanning electron microscope. With the effects of mechanical interlocking, chemical grafting, and annealing, the interfacial adhesive strength between films and PET sheets was enhanced to 12 N cm-1. The tensile strength of the Ag/CNT composite films was observed to increase by 38% by adding 5 g l-1 MWCNTs. In the four-probe method, the resistivity of Ag/CNT-5 declined by 78.2% compared with pristine Ag films. The anti-fatigue performance of the Ag/CNT composite films was monitored by cyclic bending deformation and the results revealed that the growth rate of electrical resistance during the deformation was obviously retarded. As for industrial application, this method provides an efficient low-cost way to prepare Ag/CNT composite films and can be further applied to other coating systems.

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

    CSIR Research Space (South Africa)

    Malwela, T

    2014-01-01

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

  7. Use of Gallic Acid to Enhance the Antioxidant and Mechanical Properties of Active Fish Gelatin Film.

    Science.gov (United States)

    Limpisophon, Kanokrat; Schleining, Gerhard

    2017-01-01

    This study explores the potential roles of gallic acid in fish gelatin film for improving mechanical properties, UV barrier, and providing antioxidant activities. Glycerol, a common used plasticizer, also impacts on mechanical properties of the film. A factorial design was used to investigate the effects of gallic acid and glycerol concentrations on antioxidant activities and mechanical properties of fish gelatin film. Increasing the amount of gallic acid increased the antioxidant capacities of the film measured by radical scavenging assay and the ferric reducing ability of plasma assay. The released antioxidant power of gallic acid from the film was not reduced by glycerol. The presence of gallic acid not only increased the antioxidant capacity of the film, but also increased the tensile strength, elongation at break, and reduced UV absorption due to interaction between gallic acid and protein by hydrogen bonding. Glycerol did not affect the antioxidant capacities of the film, but increased the elasticity of the films. Overall, this study revealed that gallic acid entrapped in the fish gelatin film provided antioxidant activities and improved film characteristics, namely UV barrier, strength, and elasticity of the film. © 2016 Institute of Food Technologists®.

  8. Optimization of ion assist beam deposition of magnesium oxide template films during initial nucleation and growth

    Energy Technology Data Exchange (ETDEWEB)

    Groves, James R [Los Alamos National Laboratory; Matias, Vladimir [Los Alamos National Laboratory; Stan, Liliana [Los Alamos National Laboratory; De Paula, Raymond F [Los Alamos National Laboratory; Hammond, Robert H [STANFORD UNIV.; Clemens, Bruce M [STANFOED UNIV.

    2010-01-01

    Recent efforts in investigating the mechanism of ion beam assisted deposition (IBAD) of biaxially textured thin films of magnesium oxide (MgO) template layers have shown that the texture develops suddenly during the initial 2 nm of deposition. To help understand and tune the behavior during this initial stage, we pre-deposited thin layers of MgO with no ion assist prior to IBAD growth of MgO. We found that biaxial texture develops for pre-deposited thicknesses < 2 nm, and that the thinnest layer tested, at 1 nm, resulted in the best qualitative RHEED image, indicative of good biaxial texture development. The texture developed during IBAD growth on the 1.5 nm pre-deposited layer is slightly worse and IBAD growth on the 2 nm pre-deposited layer produces a fiber texture. Application of these layers on an Al{sub 2}O{sub 3} starting surface, which has been shown to impede texture development, improves the overall quality of the IBAD MgO and has some of the characteristics of a biaxially texture RHEED pattern. It is suggested that the use of thin (<2 nm) pre-deposited layers may eliminate the need for bed layers like Si{sub 3}N{sub 4} and Y{sub 2}O{sub 3} that are currently thought to be required for proper biaxial texture development in IBAD MgO.

  9. Modification of mechanical and thermal property of chitosan–starch blend films

    International Nuclear Information System (INIS)

    Tuhin, Mohammad O.; Rahman, Nazia; Haque, M.E.; Khan, Ruhul A.; Dafader, N.C.; Islam, Rafiqul; Nurnabi, Mohammad; Tonny, Wafa

    2012-01-01

    Chitosan–starch blend films (thickness 0.2 mm) of different composition were prepared by casting and their mechanical properties were studied. To improve the properties of chitosan–starch films, glycerol and mustard oil of different composition were used. Chitosan–starch films, incorporated with glycerol and mustard oil, were further modified with monomer 2-hydroxyethyl methacrylate (HEMA) using gamma radiation. The modified films showed improvement in both tensile strength and elongation at break than the pure chitosan–starch films. Water uptake of the films reduced significantly than the pure chitosan–starch film. Thermo gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) showed that the modified films experience less thermal degradation than the pure films. Scanning electron microscopy (SEM) and FTIR were used to investigate the morphology and molecular interaction of the blend film, respectively. - Highlights: ► Chitosan–starch blend films (thickness 0.2 mm) were prepared by casting. ► To improve the properties of chitosan–starch films, glycerol and mustard oil of different composition were used. ► Chitosan–starch films, incorporated with glycerol and mustard oil, were further modified with monomer 2-hydroxyethyl methacrylate (HEMA) using gamma radiation. ► Properties of the modified films such as tensile strength, elongation at break, water uptake, TGA, DMA, SEM, FTIR were studied. ► Results indicate that modification of chitosan–starch film with mustard oil improved the properties of the blend films which could be further modified by HEMA using gamma radiation.

  10. Growth, structure and magnetic properties of magnetron sputtered FePt thin films

    Energy Technology Data Exchange (ETDEWEB)

    Cantelli, Valentina

    2010-07-01

    The L1{sub 0} FePt phase belongs to the most promising hard ferromagnetic materials for high density recording media. The main challenges for thin FePt films are: (i) to lower the process temperature for the transition from the soft magnetic A1 to the hard magnetic L1{sub 0} phase, (ii) to realize c-axes preferential oriented layers independently from the substrate nature and (iii) to control layer morphology supporting the formation of FePt-L1{sub 0} selforganized isolated nanoislands towards an increase of the signal-to-noise ratio. In this study, dc magnetron sputtered FePt thin films on amorphous substrates were investigated. The work is focused on the correlation between structural and magnetic properties with respect to the influence of deposition parameters like growth mode (cosputtering vs. layer - by - layer) and the variation of the deposition gas (Ar, Xe) or pressure (0.3-3 Pa). In low-pressure Ar discharges, high energetic particle impacts support vacancies formation during layer growth lowering the phase transition temperature to (320{+-}20) C. By reducing the particle kinetic energy in Xe discharges, highly (001) preferential oriented L1{sub 0}-FePt films were obtained on a-SiO{sub 2} after vacuum annealing. L1{sub 0}-FePt nano-island formation was supported by the introduction of an Ag matrix, or by random ballistic aggregation and atomic self shadowing realized by FePt depositions at very high pressure (3 Pa). The high coercivity (1.5 T) of granular, magnetic isotropic FePt layers, deposited in Ar discharges, was measured with SQUID magnetometer hysteresis loops. For non-granular films with (001) preferential orientation the coercivity decreased (0.6 T) together with an enhancement of the out-of- plane anisotropy. Nanoislands show a coercive field close to the values obtained for granular layers but exhibit an in-plane easy axis due to shape anisotropy effects. An extensive study with different synchrotron X-ray scattering techniques, mainly

  11. KMCThinFilm: A C++ Framework for the Rapid Development of Lattice Kinetic Monte Carlo (kMC) Simulations of Thin Film Growth

    Science.gov (United States)

    2015-09-01

    196–201. 44. Kratzer P. Monte Carlo and kinetic Monte Carlo methods–a tutorial. In: Grotendorst J, Attig N, Blügel S, Marx D, editors. Multiscale...Monte Carlo (kMC) Simulations of Thin Film Growth by James J Ramsey Approved for public release; distribution is...Research Laboratory KMCThinFilm: A C++ Framework for the Rapid Development of Lattice Kinetic Monte Carlo (kMC) Simulations of Thin Film Growth by

  12. Atomic Layer Deposition of Aluminum Sulfide: Growth Mechanism and Electrochemical Evaluation in Lithium-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Xiangbo [Department; Cao, Yanqiang [Energy; Libera, Joseph A. [Energy; Elam, Jeffrey W. [Energy

    2017-10-17

    This study describes the synthesis of aluminum sulfide (AlSx) thin films by atomic layer deposition (ALD) using tris(dimethylamido)aluminum and hydrogen sulfide. We employed a suite of in situ measurement techniques to explore the ALD AlSx growth mechanism, including quartz crystal microbalance, quadrupole mass spectrometry, and Fourier transform infrared spectroscopy. A variety of ex situ characterization techniques were used to determine the growth characteristics, morphology, elemental composition, and crystallinity of the resultant AlSx films. This study revealed that the AlSx growth was self-limiting in the temperature range 100-250 degrees C, and the growth per cycle decreased linearly with increasing temperature from similar to 0.45 angstrom/cycle at 100 degrees C to similar to 0.1 angstrom/cycle at 250 degrees C. The AlSx films were amorphous in this temperature range. We conducted electrochemical testing to evaluate the ALD AlSx as a potential anode material for lithium-ion batteries (LIBs). The ALD AlSx exhibited reliable cyclability over 60 discharge-charge cycles with a sustainable discharge capacity of 640 mAh/g at a current density of 100 mA/g in the voltage window of 0.6-3.5

  13. Epitaxial growth of higher transition-temperature VO2 films on AlN/Si

    Directory of Open Access Journals (Sweden)

    Tetiana Slusar

    2016-02-01

    Full Text Available We report the epitaxial growth and the mechanism of a higher temperature insulator-to-metal-transition (IMT of vanadium dioxide (VO2 thin films synthesized on aluminum nitride (AlN/Si (111 substrates by a pulsed-laser-deposition method; the IMT temperature is TIMT ≈ 350 K. X-ray diffractometer and high resolution transmission electron microscope data show that the epitaxial relationship of VO2 and AlN is VO2 (010 ‖ AlN (0001 with VO2 [101] ‖   AlN   [ 2 1 ̄ 1 ̄ 0 ] zone axes, which results in a substrate-induced tensile strain along the in-plane a and c axes of the insulating monoclinic VO2. This strain stabilizes the insulating phase of VO2 and raises TIMT for 10 K higher than TIMT single crystal ≈ 340 K in a bulk VO2 single crystal. Near TIMT, a resistance change of about four orders is observed in a thick film of ∼130 nm. The VO2/AlN/Si heterostructures are promising for the development of integrated IMT-Si technology, including thermal switchers, transistors, and other applications.

  14. Photoelectron diffraction study of Rh nanoparticles growth on Fe3O4/Pd(111) ultrathin film

    International Nuclear Information System (INIS)

    Abreu, G. J. P.; Pancotti, A; Lima, L. H. de; Landers, R.; Siervo, A. de

    2013-01-01

    Metallic nanoparticles (NPs) supported on oxides thin films are commonly used as model catalysts for studies of heterogeneous catalysis. Several 4d and 5d metal NPs (for example, Pd, Pt and Au) grown on alumina, ceria and titania have shown strong metal support interaction (SMSI), for instance the encapsulation of the NPs by the oxide. The SMSI plays an important role in catalysis and is very dependent on the support oxide used. The present work investigates the growth mechanism and atomic structure of Rh NPs supported on epitaxial magnetite Fe 3 O 4 (111) ultrathin films prepared on Pd(111) using the Molecular Beam Epitaxy (MBE) technique. The iron oxide and the Rh NPs were characterized using X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction and photoelectron diffraction (PED). The combined XPS and PED results indicate that Rh NPs are metallic, cover approximately 20 % of the iron oxide surface and show height distribution ranging 3–5 ML (monolayers) with essentially a bulk fcc structure.

  15. Heteroepitaxial growth and electric properties of (110)-oriented scandium nitride films

    Science.gov (United States)

    Ohgaki, Takeshi; Sakaguchi, Isao; Ohashi, Naoki; Haneda, Hajime

    2017-10-01

    ScN films were grown on MgO(110) substrates and α-Al2O3(10 1 bar 0) substrates by a molecular beam epitaxy method, and their crystalline orientation, crystallinity, and electric properties were examined. (110)-oriented ScN films were epitaxially grown on MgO(110) substrates with the same crystal orientations, and ScN films with an orientation relationship (110)ScN || (10 1 bar 0)α-Al2O3 and [001]ScN || [ 1 2 bar 10 ]α-Al2O3 were epitaxially grown on α-Al2O3(10 1 bar 0) substrates. Remarkably, electric-resistivity anisotropy was observed for ScN films grown on MgO(110) substrates, and the anisotropy depended on the growth temperature. The carrier concentration and Hall mobility of the ScN films grown on α-Al2O3(10 1 bar 0) substrates ranged from 1019-1021 cm-3 and 10-150 cm2 V-1 s-1, respectively. The crystallinity, crystalline-orientation anisotropy, and electric properties of the films were strongly affected by growth conditions. For the growth of ScN films with high mobility on α-Al2O3(10 1 bar 0) substrates, a high temperature and an appropriate ratio of source materials were necessary.

  16. Growth of magnetite films by a hydrogel method

    Energy Technology Data Exchange (ETDEWEB)

    Velásquez, A.A., E-mail: avelas26@eafit.edu.edu.co [Grupo de Electromagnetismo Aplicado, Universidad EAFIT, A.A. 3300, Medellín (Colombia); Marín, C.C. [Grupo de Electromagnetismo Aplicado, Universidad EAFIT, A.A. 3300, Medellín (Colombia); Urquijo, J.P. [Grupo de Estado Sólido, Instituto de Física, Universidad de Antioquia, A.A. 1226, Medellín (Colombia)

    2017-06-15

    Magnetite (Fe{sub 3}O{sub 4}) films were grown on glass substrates by formation and condensation of complex of iron oxides in an agarose hydrogel. The obtained films were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Room Temperature Mössbauer Spectroscopy (TMS), Vibrating Sample Magnetometry (VSM), Atomic Force Microscopy (AFM) and Voltage vs. Current measurements by the four-point method. FTIR and TGA measurements showed that some polymer chains of agarose remain linked to the surface of the magnetic particles of the films after heat treatment. SEM measurements showed that the films are composed by quasi spherical particles with sizes around 55 nm. Mössbauer spectroscopy measurements showed two sextets with broaden lines, which were assigned to magnetite with a distributed particle size, and two doublets, which were assigned to superparamagnetic phases of magnetite. For the specific dimensions of the films prepared, measurements of Voltage vs. Current showed an ohmic behavior for currents between 0 and 200 nA, with a resistance of 355 kΩ.

  17. The growth of thin film epitaxial oxide-metal heterostructures

    CERN Document Server

    Wang, C

    1998-01-01

    films with lowest IR emissivity are those made from the purest targets despite their having comparable roughnesses to films from lower purity targets. The lowest emissivity achieved was in the range of 1.64% to 1.72% measured at 3.8 mu m for 1.5 to 1.8 mu m thick films. Modifications to standard idealized Drude theory have been made which, in a phenomenological way, take account of imperfections in the sputtered Al film, oxidation state and roughness. in electric properties of the Nb film and the reduction in crystalline quality of the MgO layer. The reduction of transition temperature to the superconducting state, Tc, and the similarly systematic increase in the Nb lattice parameter were observed consistent with oxygen content data reported in the literature, as the Nb became heavily oxidized. Examination of the surface of clean and oxidized Nb by atomic force microscopy, and deposition of MgO in UHV onto a previously oxidized Nb surface, suggested that the decrease in crystalline quality of the MgO can be a...

  18. Molecular dynamics simulation about porous thin-film growth in secondary deposition

    International Nuclear Information System (INIS)

    Chen Huawei; Tieu, A. Kiet; Liu Qiang; Hagiwara, Ichiro; Lu Cheng

    2007-01-01

    The thin film growth has been confirmed to be assembled by an enormous number of clusters in experiments of CVD. Sequence of clusters' depositions proceeds to form the thin film at short time as gas fluids through surface of substrate. In order to grow condensed thin film using series of cluster deposition, the effect of initial velocity, substrate temperature and density of clusters on property of deposited thin film, especially appearance of nanoscale pores inside thin film must be investigated. In this simulation, three different cluster sizes of 203, 653, 1563 atoms with different velocities (0, 10, 100, 1000 and 3000 m/s) were deposited on a Cu(0 0 1) substrate whose temperatures were set between 300 and 1000 K. Four clusters and one cluster were used in primary deposition and secondary deposition, respectively. We have clarified that adhesion between clusters and substrate is greatly influenced by initial velocity. As a result, the exfoliation pattern of deposited thin film is dependent on initial velocity and different between them. One borderline dividing whole region into porous region and nonporous region are obtained to show the effect of growth conditions on appearance of nanoscale pores inside thin film. Moreover, we have also shown that the likelihood of porous thin film is dependent on the point of impact of a cluster relative to previously deposited clusters

  19. Atomistic growth phenomena of reactively sputtered RuO2 and MnO2 thin films

    International Nuclear Information System (INIS)

    Music, Denis; Bliem, Pascal; Geyer, Richard W.; Schneider, Jochen M.

    2015-01-01

    We have synthesized RuO 2 and MnO 2 thin films under identical growth conditions using reactive DC sputtering. Strikingly different morphologies, namely, the formation of RuO 2 nanorods and faceted, nanocrystalline MnO 2 , are observed. To identify the underlying mechanisms, we have carried out density functional theory based molecular dynamics simulations of the growth of one monolayer. Ru and O 2 molecules are preferentially adsorbed at their respective RuO 2 ideal surface sites. This is consistent with the close to defect free growth observed experimentally. In contrast, Mn penetrates the MnO 2 surface reaching the third subsurface layer and remains at this deep interstitial site 3.10 Å below the pristine surface, resulting in atomic scale decomposition of MnO 2 . Due to this atomic scale decomposition, MnO 2 may have to be renucleated during growth, which is consistent with experiments

  20. Engineering the mechanical properties of ultrabarrier films grown by atomic layer deposition for the encapsulation of printed electronics

    Energy Technology Data Exchange (ETDEWEB)

    Bulusu, A.; Singh, A.; Kim, H. [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Wang, C. Y.; Dindar, A.; Fuentes-Hernandez, C.; Kippelen, B. [School of Electrical and Computer Engineering, Georgia Institute of Technology, and Center for Organic Photonics and Electronics, Atlanta, Georgia 30332 (United States); Cullen, D. [Oak Ridge National Laboratory, P.O. Box 2008 MS-6064, Oak Ridge, Tennessee 37831 (United States); Graham, S., E-mail: sgraham@gatech.edu [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Oak Ridge National Laboratory, P.O. Box 2008 MS-6064, Oak Ridge, Tennessee 37831 (United States)

    2015-08-28

    Direct deposition of barrier films by atomic layer deposition (ALD) onto printed electronics presents a promising method for packaging devices. Films made by ALD have been shown to possess desired ultrabarrier properties, but face challenges when directly grown onto surfaces with varying composition and topography. Challenges include differing nucleation and growth rates across the surface, stress concentrations from topography and coefficient of thermal expansion mismatch, elastic constant mismatch, and particle contamination that may impact the performance of the ALD barrier. In such cases, a polymer smoothing layer may be needed to coat the surface prior to ALD barrier film deposition. We present the impact of architecture on the performance of aluminum oxide (Al{sub 2}O{sub 3})/hafnium oxide (HfO{sub 2}) ALD nanolaminate barrier films deposited on fluorinated polymer layer using an optical calcium (Ca) test under damp heat. It is found that with increasing polymer thickness, the barrier films with residual tensile stress are prone to cracking resulting in rapid failure of the Ca sensor at 50 °C/85% relative humidity. Inserting a SiN{sub x} layer with residual compressive stress between the polymer and ALD layers is found to prevent cracking over a range of polymer thicknesses with more than 95% of the Ca sensor remaining after 500 h of testing. These results suggest that controlling mechanical properties and film architecture play an important role in the performance of direct deposited ALD barriers.

  1. Introducing Viewpoints of Mechanics into Basic Growth Analysis : (VII) Mathematical Properties of Basic Growth Mechanics in Ruminant

    OpenAIRE

    Shimojo, Masataka; Shao, Tao; Masuda, Yasuhisa; 下條, 雅敬; 増田, 泰久

    2008-01-01

    This study was conducted to investigate mathematical properties of basic growth mechanics in ruminant by introducing newly developed viewpoints into mathematical operations of basic growth function. The negative sign, which appeared naturally by taking the square root of the differential equation based on basic growth mechanics, gave mathematical contradictions to the differential principle. In the process of correcting those contradictions, viewpoints of interest were newly introduced to giv...

  2. Self-regulated growth of LaVO3 thin films by hybrid molecular beam epitaxy

    International Nuclear Information System (INIS)

    Zhang, Hai-Tian; Engel-Herbert, Roman; Dedon, Liv R.; Martin, Lane W.

    2015-01-01

    LaVO 3 thin films were grown on SrTiO 3 (001) by hybrid molecular beam epitaxy. A volatile metalorganic precursor, vanadium oxytriisopropoxide (VTIP), and elemental La were co-supplied in the presence of a molecular oxygen flux. By keeping the La flux fixed and varying the VTIP flux, stoichiometric LaVO 3 films were obtained for a range of cation flux ratios, indicating the presence of a self-regulated growth window. Films grown under stoichiometric conditions were found to have the largest lattice parameter, which decreased monotonically with increasing amounts of excess La or V. Energy dispersive X-ray spectroscopy and Rutherford backscattering measurements were carried out to confirm film compositions. Stoichiometric growth of complex vanadate thin films independent of cation flux ratios expands upon the previously reported self-regulated growth of perovskite titanates using hybrid molecular beam epitaxy, thus demonstrating the general applicability of this growth approach to other complex oxide materials, where a precise control over film stoichiometry is demanded by the application

  3. Mechanical, physico-chemical, and antimicrobial properties of gelatin-based film incorporated with catechin-lysozyme

    Directory of Open Access Journals (Sweden)

    Rawdkuen Saroat

    2012-11-01

    Full Text Available Abstract Background Microbial activity is a primary cause of deterioration in many foods and is often responsible for reduced quality and safety. Food-borne illnesses associated with E. coli O157:H7, S. aureus, S. enteritidis and L. monocytogenes are a major public health concern throughout the world. A number of methods have been employed to control or prevent the growth of these microorganisms in food. Antimicrobial packaging is one of the most promising active packaging systems for effectively retarding the growth of food spoilage and pathogenic microorganisms. The aim of this study was to determine the mechanical, physico-chemical properties and inhibitory effects of the fish gelatin films against selected food spoilage microorganisms when incorporated with catechin-lysozyme. Results The effect of the catechin-lysozyme combination addition (CLC: 0, 0.125, 0.25, and 0.5%, w/v on fish gelatin film properties was monitored. At the level of 0.5% addition, the CLC showed the greatest elongation at break (EAB at 143.17% with 0.039 mm thickness, and the lowest water vapor permeability (WVP at 6.5 x 10−8 g·mm·h-1·cm-2·Pa-1, whereas the control showed high tensile strength (TS and the highest WVP. Regarding color attributes, the gelatin film without CLC addition gave the highest lightness (L* 91.95 but lowest in redness (a*-1.29 and yellowness (b* 2.25 values. The light transmission of the film did not significantly decrease and nor did film transparency (p>0.05 with increased CLC. Incorporating CLC could not affect the film microstructure. The solubility of the gelatin based film incorporated with CLC was not affected, especially at a high level of addition (p>0.05. Inhibitory activity of the fish gelatin film against E.coli, S.aureus, L. innocua and S. cerevisiae was concentration dependent. Conclusions These findings suggested that CLC incorporation can improve mechanical, physico-chemical, and antimicrobial properties of the resulting films

  4. Mechanical control of growth: ideas, facts and challenges.

    Science.gov (United States)

    Irvine, Kenneth D; Shraiman, Boris I

    2017-12-01

    In his classic book On Growth and Form , D'Arcy Thompson discussed the necessity of a physical and mathematical approach to understanding the relationship between growth and form. The past century has seen extraordinary advances in our understanding of biological components and processes contributing to organismal morphogenesis, but the mathematical and physical principles involved have not received comparable attention. The most obvious entry of physics into morphogenesis is via tissue mechanics. In this Review, we discuss the fundamental role of mechanical interactions between cells induced by growth in shaping a tissue. Non-uniform growth can lead to accumulation of mechanical stress, which in the context of two-dimensional sheets of tissue can specify the shape it assumes in three dimensions. A special class of growth patterns - conformal growth - does not lead to the accumulation of stress and can generate a rich variety of planar tissue shapes. Conversely, mechanical stress can provide a regulatory feedback signal into the growth control circuit. Both theory and experiment support a key role for mechanical interactions in shaping tissues and, via mechanical feedback, controlling epithelial growth. © 2017. Published by The Company of Biologists Ltd.

  5. Dynamic mechanical behaviour of nanoparticle loaded biodegradable PVA films for vaginal drug delivery.

    Science.gov (United States)

    Traore, Yannick L; Fumakia, Miral; Gu, Jijin; Ho, Emmanuel A

    2018-03-01

    In this study, we investigated the viscoelastic and mechanical behaviour of polyvinyl alcohol films formulated along with carrageenan, plasticizing agents (polyethylene glycol and glycerol), and when loaded with nanoparticles as a model for potential applications as microbicides. The storage modulus, loss modulus and glass transition temperature were determined using a dynamic mechanical analyzer. Films fabricated from 2% to 5% polyvinyl alcohol containing 3 mg or 5 mg of fluorescently labeled nanoparticles were evaluated. The storage modulus and loss modulus values of blank films were shown to be higher than the nanoparticle-loaded films. Glass transition temperature determined using the storage modulus, and loss modulus was between 40-50℃ and 35-40℃, respectively. The tensile properties evaluated showed that 2% polyvinyl alcohol films were more elastic but less resistant to breaking compared to 5% polyvinyl alcohol films (2% films break around 1 N load and 5% films break around 7 N load). To our knowledge, this is the first study to evaluate the influence of nanoparticle and film composition on the physico-mechanical properties of polymeric films for vaginal drug delivery.

  6. Dynamic mechanical analysis of single walled carbon nanotubes/polymethyl methacrylate nanocomposite films

    International Nuclear Information System (INIS)

    Badawi, Ali; Al Hosiny, N.

    2015-01-01

    Dynamic mechanical properties of nanocomposite films with different ratios of single walled carbon nanotubes/polymethyl methacrylate (SWCNTs/PMMA) are studied. Nanocomposite films of different ratios (0, 0.5, 1.0, and 2.0 weight percent (wt%)) of SWCNTs/PMMA are fabricated by using a casting technique. The morphological and structural properties of both SWCNT powder and SWCNTs/PMMA nanocomposite films are investigated by using a high resolution transmission electron microscope and x-ray diffractometer respectively. The mechanical properties including the storage modulus, loss modulus, loss factor (tan δ) and stiffness of the nanocomposite film as a function of temperature are recorded by using a dynamic mechanical analyzer at a frequency of 1 Hz. Compared with pure PMMA film, the nanocomposite films with different ratios of SWCNTs/PMMA are observed to have enhanced storage moduli, loss moduli and high stiffness, each of which is a function of temperature. The intensity of the tan δ peak for pure PMMA film is larger than those of the nanocomposite films. The glass transition temperature (T g ) of SWCNTs/PMMA nanocomposite film shifts towards the higher temperature side with respect to pure PMMA film from 91.2 °C to 99.5 °C as the ratio of SWCNTs/PMMA increases from 0 to 2.0 wt%. (paper)

  7. Pectin- and gelatin-based film: effect of gamma irradiation on the mechanical properties and biodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Cheorun; Kang, Hojin; Lee, Na Young; Kwon, Joong Ho; Byun, Myung Woo E-mail: mwbyun@kaeri.re.kr

    2005-04-01

    Agricultural by-products, pectin and gelatin, were used to prepare a biodegradable film. The film casting solution including the pectin and gelatin was irradiated at 0, 10, 20, and 30 kGy to investigate the irradiation effect on the mechanical properties of the film. The tensile strength of the 10 kGy-irradiated film was the highest among the treatments but the elongation at break, water vapour permeability, and swelling ratio were the lowest. Hunter color L*- and a*-values decreased but the b*-value increased as the irradiation dose increased. The total organic carbon content produced from the Paenibacillus polymyxa and Pseudomonas aeruginosa also showed that the film of 10 kGy-irradiated was lower than those of 0, 20, and 30 kGy-irradiated films. In conclusion, irradiation of the film casting solution at 10 kGy increased the mechanical properties of the pectin and gelatin based film. To manufacture the film by agricultural by-products, however, the irradiation dose of the film casting solution should be determined to achieve better mechanical properties.

  8. Stability of Newton black films under mechanical stretch--a molecular dynamics study.

    Science.gov (United States)

    Shen, Zhe; Sun, Huai; Liu, Xiaoyan; Liu, Wenting; Tang, Ming

    2013-09-10

    The stability of Newton black films (NBFs) under lateral mechanical stretch was investigated by nonequilibrium molecular dynamics (NEMD) simulations using force field parameters validated by accurate prediction of surface tensions. The applied strains accelerated film ruptures, enabling efficient measurements of the critical thicknesses of the films. Two representative surfactants, sodium dodecyl sulfate (SDS) for ionic surfactant and pentaethylene glycol monododecyl ether (C12EO5H) for nonionic surfactant, were investigated and compared. The predicted critical thickness of C12EO5H-coated film is smaller than that of the SDS-coated film, which is consistent with previously reported experimental observations. Our simulation results show that while the two surfactant-coated films exhibit similar dynamic properties attributed to the Marangoni-Gibbs effect, their surface structural characteristics are quite different. Consequently the two films demonstrate distinct rupture mechanisms in which rupture starts at uncovered water domains in the SDS-coated film, but at lateral surfactant/water interfaces in the C12EO5H-coated film. Our findings provide new insights into the stabilization mechanisms of NBFs and will facilitate the design and development of new films with improved properties.

  9. Surface structure deduced differences of copper foil and film for graphene CVD growth

    International Nuclear Information System (INIS)

    Tian, Junjun; Hu, Baoshan; Wei, Zidong; Jin, Yan; Luo, Zhengtang; Xia, Meirong; Pan, Qingjiang; Liu, Yunling

    2014-01-01

    Highlights: • We demonstrate the significant differences between Cu foil and film in the surface morphology and crystal orientation distribution. • The different surface structure leads to the distinctive influences of the CH 4 and H 2 concentrations on the thickness and quality of as-grown graphene. • Nucleation densities and growth rate differences at the initial growth stages on the Cu foil and film were investigated and discussed. - Abstract: Graphene was synthesized on Cu foil and film by atmospheric pressure chemical vapor deposition (CVD) with CH 4 as carbon source. Electron backscattered scattering diffraction (EBSD) characterization demonstrates that the Cu foil surface after the H 2 -assisted pre-annealing was almost composed of Cu(1 0 0) crystal facet with larger grain size of ∼100 μm; meanwhile, the Cu film surface involved a variety of crystal facets of Cu(1 1 1), Cu(1 0 0), and Cu(1 1 0), with the relatively small grain size of ∼10 μm. The different surface structure led to the distinctive influences of the CH 4 and H 2 concentrations on the thickness and quality of as-grown graphene. Further data demonstrate that the Cu foil enabled more nucleation densities and faster growth rates at the initial growth stages than the Cu film. Our results are beneficial for understanding the relationship between the metal surface structure and graphene CVD growth

  10. Enhancing mechanical properties of chitosan films via modification with vanillin.

    Science.gov (United States)

    Zhang, Zhi-Hong; Han, Zhong; Zeng, Xin-An; Xiong, Xia-Yu; Liu, Yu-Jia

    2015-11-01

    The vanillin/chitosan composite films were prepared using the solvent evaporation method. The properties of the films including optical property, water vapor permeability (WVP), tensile strength (TS) and elongation at break (%E) were studied to investigate the effect of cross-linking agent of vanillin on chitosan films by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectrum (FT-IR). Results showed that the TS of composite films increased by 53.3% and the WVP decreased by 36.5% compared with pure chitosan film that were due to the formation of the dense network structure by FT-IR spectra. There were almost no changes of the thermal stability of the composite films compared with the pure chitosan film by TGA analysis. In addition, from the SEM images, it could be seen that the film with addition of vanillin with 0.5-10% concentration exhibited good compatibility. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Transparent conducting film: Effect of mechanical stretching to ...

    Indian Academy of Sciences (India)

    Administrator

    posite was fixed to a tabletop clamp and unidirectionally stretched after cutting the paper support at two opposite sides. To hold the film under the stretched condition, both edges of stretched CNT-mat/transparent-film composite was then adhered to a PMMA substrate by epoxy glue and both the sheet resistance and the ...

  12. Optical and mechanical properties of diamond like carbon films ...

    Indian Academy of Sciences (India)

    Wintec

    gases. During deposition, a d.c. self-bias was applied to the substrates by application of 13⋅56 MHz rf power. DLC films deposited at three ... modulus were measured by load depth sensing indentation technique. The DLC film deposited at ... d.c. self bias (developed with the application of RF power to the substrates) and to ...

  13. Optical and mechanical properties of diamond like carbon films ...

    Indian Academy of Sciences (India)

    Wintec

    Diamond like carbon (DLC) films were deposited on Si (111) substrates by microwave electron cyclo- ... coatings on tools used in applications that require low ..... G peak for film deposited at –100 V bias is towards lower wave number. This coupled with decrease in ID/IG is strongly indicative of an increase in the ratio of sp.

  14. Mechanical stretch influence on lifetime of dielectric elastomer films

    NARCIS (Netherlands)

    Iannarelli, A.; Ghaffarian Niasar, M.; Bar-Cohen, Yoseph

    2017-01-01

    Film pre-stretching is a widely adopted solution to improve dielectric strength of the DEA systems. However, to date, long term reliability of this solution has not been investigated. In this work it is explored how the dielectric elastomer lifetime is affected by film pre-stretching. The dielectric

  15. Mechanical, barrier and morphological properties of pea starch and peanut protein isolate blend films.

    Science.gov (United States)

    Sun, Qingjie; Sun, Cuixia; Xiong, Liu

    2013-10-15

    Mechanical, barrier and morphological properties of edible films based on blends of Pea starch (PS) and Peanut protein isolate (PPI) plasticized with glycerol (30%, w/w) were investigated. As PPI ratio in PS/PPI blends increased, the thickness of films decreased, the opacity slightly elevated and color intensified. The addition of PPI to the PS film significantly reduced tensile strength from 5.44 MPa to 3.06 MPa, but increased elongation from 28.56% to 98.12% with the incorporation of PPI into PS at 50% level. Film solubility value fell from 22.31% to 9.78% upon the incorporation of PPI ranged from 0 to 50% level. When PPI was added into PS film at 40% level, the WVP and WVTR of the films markedly dropped from 11.18% to 4.19% and 6.16 to 1.95%, respectively. Scanning electron microscopy (SEM) of the surface of films showed that many swollen starch granules were presented in the 100% PS film, while 100% PPI film was observed to have rougher surfaces with presence of pores or cavities. The PS/PPI blend films upon the incorporation of PPI at 20% and 50% level were not homogeneous. However, the smoother film surface was observed in PS/PPI blend films with the addition of PPI at 40% level. SEM image of the cross-sections of the films revealed that the 100% PS film showed a uniform and compact matrix without disruption, and pore formation and 100% PPI film displayed a smooth structure. Rougher and flexible network was shown in blend film with the addition of PPI reaching 40% level. Copyright © 2013. Published by Elsevier Ltd.

  16. Investigation of Carboxymethyl Cellulose (CMC on Mechanical Properties of Cold Water Fish Gelatin Biodegradable Edible Films

    Directory of Open Access Journals (Sweden)

    Mahsa Tabari

    2017-05-01

    Full Text Available The tendency to use biocompatible packages, such as biodegradable films, is growing since they contain natural materials, are recyclable and do not cause environmental pollution. In this research, cold water fish gelatin and carboxymethyl cellulose were combined for use in edible films. Due to its unique properties, gelatin is widely used in creating gel, and in restructuring, stabilizing, emulsifying, and forming foam and film in food industries. This research for the first time modified and improved the mechanical properties of cold water fish gelatin films in combination with carboxymethyl cellulose. Cold water fish gelatin films along with carboxymethyl cellulose with concentrations of 0%, 5%, 10%, 20% and 50% were prepared using the casting method. The mechanical properties were tested by the American National Standard Method. Studying the absorption isotherm of the resulting composite films specified that the humidity of single-layer water decreased (p < 0.05 and caused a reduction in the equilibrium moisture of these films. In the mechanical testing of the composite films, the tensile strength and Young’s modulus significantly increased and the elongation percent significantly decreased with the increase in the concentration of carboxymethyl cellulose. Considering the biodegradability of the films and the improvement of their mechanical properties by carboxymethyl cellulose, this kind of packaging can be used in different industries, especially the food industry, as an edible coating for packaging food and agricultural crops.

  17. Mechanisms of stress generation and relaxation during pulsed laser deposition of epitaxial Fe-Pd magnetic shape memory alloy films on MgO

    International Nuclear Information System (INIS)

    Edler, Tobias; Mayr, S G; Buschbeck, Joerg; Mickel, Christine; Faehler, Sebastian

    2008-01-01

    Mechanical stress generation during epitaxial growth of Fe-Pd thin films on MgO from pulsed laser deposition is a key parameter for the suitability in shape memory applications. By employing in situ substrate curvature measurements, we determine the stress states as a function of film thickness and composition. Depending on composition, different stress states are observed during initial film growth, which can be attributed to different misfits. Compressive stress generation by atomic peening is observed in the later stages of growth. Comparison with ex situ x-ray based strain measurements allows integral and local stress to be distinguished and yields heterogeneities of the stress state between coherent and incoherent regions. In combination with cross-sectional TEM measurements the relevant stress relaxation mechanism is identified to be stress-induced martensite formation with (111) twinning

  18. Mechanical properties of phosphorus-doped polysilicon films

    CERN Document Server

    Lee, S W; Kim, J P; Park, S J; Yi, S W; Cho, D I; Kim, J J

    1998-01-01

    Polysilicon films deposited by low pressure chemical vapor deposition (LPCVD) are the most widely used structural material in microelectromechanical systems (MEMS). However, the structural properties of LPCVD polysilicon films are known to vary significantly, depending on deposition conditions as well as post-deposition processes. This paper investigates the effects of phosphorus doping and texture on Young's modulus of polysilicon films. Polysilicon films are deposited at 585 .deg. C, 605 .deg. C, and 625 .deg. C to a thickness of 2 mu m. Specimens with varying phosphorus doping levels are prepared by the diffusion process at various temperatures and times using both POCl sub 3 and phosphosilicate glass (PSG) source. Texture is measured using an X-ray diffractometer. Young's modulus is estimated from the average values of the resonant frequencies measured from four-different size lateral resonators. Our results show that Young's modulus of diffusion doped polysilicon films decreases with increasing doping co...

  19. Grain boundaries and mechanical properties of nanocrystalline diamond films.

    Energy Technology Data Exchange (ETDEWEB)

    Busmann, H.-G.; Pageler, A.; Gruen, D. M.

    1999-08-06

    Phase-pure nanocrystalline diamond thin films grown from plasmas of a hydrogen-poor carbon argon gas mixture have been analyzed regarding their hardness and elastic moduli by means of a microindentor and a scanning acoustic microscope.The films are superhard and the moduli rival single crystal diamond. In addition, Raman spectroscopy with an excitation wavelength of 1064 nm shows a peak at 1438 l/cm and no peak above 1500 l/cm, and X-ray photoelectron spectroscopy a shake-up loss at 4.2 eV. This gives strong evidence for the existence of solitary double bonds in the films. The hardness and elasticity of the films then are explained by the assumption, that the solitary double bonds interconnect the nanocrystals in the films, leading to an intergrain boundary adhesion of similar strength as the intragrain diamond cohesion. The results are in good agreement with recent simulations of high-energy grain boundaries.

  20. Tailoring the nanoscale morphology of HKUST-1 thin films via codeposition and seeded growth.

    Science.gov (United States)

    Brower, Landon J; Gentry, Lauren K; Napier, Amanda L; Anderson, Mary E

    2017-01-01

    Integration of surface-anchored metal-organic frameworks (surMOFs) within hierarchical architectures is necessary for potential sensing, electronic, optical, or separation applications. It is important to understand the fundamentals of film formation for these surMOFs in order to develop strategies for their incorporation with nanoscale control over lateral and vertical dimensions. This research identified processing parameters to control the film morphology for surMOFs of HKUST-1 fabricated by codeposition and seeded deposition. Time and temperature were investigated to observe film formation, to control film thickness, and to tune morphology. Film thickness was investigated by ellipsometry, while film structure and film roughness were characterized by atomic force microscopy. Films formed via codeposition resulted in nanocrystallites anchored to the gold substrate. A dynamic process at the interface was observed with a low density of large particulates (above 100 nm) initially forming on the substrate; and over time these particulates were slowly replaced by the prevalence of smaller crystallites (ca. 10 nm) covering the substrate at a high density. Elevated temperature was found to expedite the growth process to obtain the full range of surface morphologies with reasonable processing times. Seed crystals formed by the codeposition method were stable and nucleated growth throughout a subsequent layer-by-layer deposition process. These seed crystals templated the final film structure and tailor the features in lateral and vertical directions. Using codeposition and seeded growth, different surface morphologies with controllable nanoscale dimensions can be designed and fabricated for integration of MOF systems directly into device architectures and sensor platforms.

  1. Tailoring the nanoscale morphology of HKUST-1 thin films via codeposition and seeded growth

    Directory of Open Access Journals (Sweden)

    Landon J. Brower

    2017-11-01

    Full Text Available Integration of surface-anchored metal-organic frameworks (surMOFs within hierarchical architectures is necessary for potential sensing, electronic, optical, or separation applications. It is important to understand the fundamentals of film formation for these surMOFs in order to develop strategies for their incorporation with nanoscale control over lateral and vertical dimensions. This research identified processing parameters to control the film morphology for surMOFs of HKUST-1 fabricated by codeposition and seeded deposition. Time and temperature were investigated to observe film formation, to control film thickness, and to tune morphology. Film thickness was investigated by ellipsometry, while film structure and film roughness were characterized by atomic force microscopy. Films formed via codeposition resulted in nanocrystallites anchored to the gold substrate. A dynamic process at the interface was observed with a low density of large particulates (above 100 nm initially forming on the substrate; and over time these particulates were slowly replaced by the prevalence of smaller crystallites (ca. 10 nm covering the substrate at a high density. Elevated temperature was found to expedite the growth process to obtain the full range of surface morphologies with reasonable processing times. Seed crystals formed by the codeposition method were stable and nucleated growth throughout a subsequent layer-by-layer deposition process. These seed crystals templated the final film structure and tailor the features in lateral and vertical directions. Using codeposition and seeded growth, different surface morphologies with controllable nanoscale dimensions can be designed and fabricated for integration of MOF systems directly into device architectures and sensor platforms.

  2. Mechanisms of pancreatic beta-cell growth and regeneration

    DEFF Research Database (Denmark)

    Nielsen, Jens Høiriis

    1989-01-01

    Information about the mechanism of beta-cell growth and regeneration may be obtained by studies of insulinoma cells. In the present study the growth and function of the rat insulinoma cell lines RINm5F and 5AH were evaluated by addition of serum, hormones, and growth factors. It was found...... of insulin mRNA content showed that the insulinoma cells only contained about 2% of that of normal rat beta-cells. These results are discussed in relation to the role of growth factors, oncogenes, and differentiation in the growth and regeneration of beta-cells....

  3. Alyssum homolocarpum seed gum-polyvinyl alcohol biodegradable composite film: Physicochemical, mechanical, thermal and barrier properties.

    Science.gov (United States)

    Monjazeb Marvdashti, Leila; Koocheki, Arash; Yavarmanesh, Masoud

    2017-01-02

    Films made from Alyssum homolocarpum seeds gum (AHSG) have poor mechanical and barrier (to oxygen) properties. In the present study poly vinyl alcohol (PVA) was used to improve the physicochemical properties of AHSG films. Results indicated that the addition of PVA significantly increased the moisture content, solubility, elongation at break (EB) and transparency while it decreased the density, oxygen permeability, chroma, water contact angle and Young modulus of AHSG based films. Films with higher AHSG to PVA ratios had lower water vapor permeability (WVP). The light barrier measurements presented low values of transparency at 600nm for PVA/AHSG films, indicating that films were very transparent while they had excellent barrier properties against UV light. Results for FTIR, DSC and SEM showed a clear interaction between PVA and AHSG, forming a new material. These results indicated that PVA/AHSG blend films had good compatibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Influence of microstructure and mechanical stress on behavior of hydrogen in 500 nm Pd films

    Energy Technology Data Exchange (ETDEWEB)

    Vlček, Marián, E-mail: Marian.Vlcek@gmail.com [Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, CZ-18000 Praha 8 (Czech Republic); Lukáč, František; Vlach, Martin [Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, CZ-18000 Praha 8 (Czech Republic); Wagner, Stefan; Uchida, Helmut [Institute of Materials Physics, University of Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Baehtz, Carsten; Shalimov, Artem [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden (Germany); Pundt, Astrid [Institute of Materials Physics, University of Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Čížek, Jakub [Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, CZ-18000 Praha 8 (Czech Republic)

    2015-10-05

    Highlights: • Influence of nano-structure and stresses on hydrogenation of Pd films was studied. • Nanocrystalline Pd films deposited on hard and soft substrates were compared. • It was found that nanocrystalline structure leads to narrowing of the miscibility gap. • Compressive in-plane stress suppresses the hydride formation. • The lattice constants for α-phase and the hydride phase are closer than in bulk Pd. - Abstract: Pd films can be used as a model system to examine the influence of microstructure and stress on the hydrogen absorption. In this work we study 500 nm Pd films deposited on different substrates with different binding strengths. The films were electrochemically loaded with hydrogen up to hydride concentration. Development of lattice constant during hydrogen loading of Pd films was investigated by in situ X-ray diffraction using synchrotron radiation. The influence of microstructure and mechanical stress in the films on the phase transition from Pd to Pd hydride was examined.

  5. Mechanisms of pancreatic beta-cell growth and regeneration

    DEFF Research Database (Denmark)

    Nielsen, Jens Høiriis

    1989-01-01

    Information about the mechanism of beta-cell growth and regeneration may be obtained by studies of insulinoma cells. In the present study the growth and function of the rat insulinoma cell lines RINm5F and 5AH were evaluated by addition of serum, hormones, and growth factors. It was found...... that transferrin is the only obligatory factor whereas growth hormone, epidermal growth factor, fibroblast growth factor, and TRH had modulating effects. A heat-labile heparin binding serum factor which stimulated thymidine incorporation but not cell proliferation was demonstrated in human serum. Measurements...... of insulin mRNA content showed that the insulinoma cells only contained about 2% of that of normal rat beta-cells. These results are discussed in relation to the role of growth factors, oncogenes, and differentiation in the growth and regeneration of beta-cells....

  6. Possibility of in situ orthorhombic I growth in YBa2Cu3Oy thin films

    International Nuclear Information System (INIS)

    Teshima, Hidekazu; Shimada, Haruo; Imafuku, Muneyuki; Tanaka, Masamoto

    1994-01-01

    We have succeeded in the true in situ preparation of superconducting YBa 2 Cu 3 O y thin films with high T c without post-oxygenation using opposed-targets magnetron sputtering. In spite of no post-oxygenation, these films showed zero resistance T c as high as 88K with a relatively sharp transition width ΔT c (90%-10%) of 2K. This suggests the possibility of in situ forming the orthorhombic I phase during growth. (orig.)

  7. Investigation of Carboxymethyl Cellulose (CMC) on Mechanical Properties of Cold Water Fish Gelatin Biodegradable Edible Films.

    Science.gov (United States)

    Tabari, Mahsa

    2017-05-27

    The tendency to use biocompatible packages, such as biodegradable films, is growing since they contain natural materials, are recyclable and do not cause environmental pollution. In this research, cold water fish gelatin and carboxymethyl cellulose were combined for use in edible films. Due to its unique properties, gelatin is widely used in creating gel, and in restructuring, stabilizing, emulsifying, and forming foam and film in food industries. This research for the first time modified and improved the mechanical properties of cold water fish gelatin films in combination with carboxymethyl cellulose. Cold water fish gelatin films along with carboxymethyl cellulose with concentrations of 0%, 5%, 10%, 20% and 50% were prepared using the casting method. The mechanical properties were tested by the American National Standard Method. Studying the absorption isotherm of the resulting composite films specified that the humidity of single-layer water decreased ( p food industry, as an edible coating for packaging food and agricultural crops.

  8. Effect of equilibrium moisture content on barrier, mechanical and thermal properties of chitosan films.

    Science.gov (United States)

    Aguirre-Loredo, Rocío Yaneli; Rodríguez-Hernández, Adriana Inés; Morales-Sánchez, Eduardo; Gómez-Aldapa, Carlos Alberto; Velazquez, Gonzalo

    2016-04-01

    Water molecules modify the properties of biodegradable films obtained from hydrophilic materials. Most studies dealing with thermal, mechanical and barrier properties of hydrophilic films are carried out under one relative humidity (RH) condition. The objective of this work was to evaluate the effect of the moisture content on the thermal, mechanical and barrier properties of chitosan films under several RH conditions. Microclimates, obtained with saturated salt solutions were used for conditioning samples and the properties of the films were evaluated under each RH condition. Chitosan films absorbed up to 40% of moisture at the higher RH studied. The percentage of elongation and the water vapour permeability increased while tensile strength, Young's modulus and glass transition temperature decreased, when the moisture content increased. The results suggest that the water molecules plasticized the polymer matrix, changing the properties when the films were in contact with high RH environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Growth and characterization of magnetite-maghemite thin films by the dip coating method

    Energy Technology Data Exchange (ETDEWEB)

    Velásquez, A. A., E-mail: avelas26@eafit.edu.edu.co; Arnedo, A. [Universidad EAFIT, Grupo de Electromagnetismo Aplicado (Colombia)

    2017-11-15

    We present the process of growth and characterization of magnetite-maghemite thin films obtained by the dip coating method. The thin films were deposited on glass substrates, using a ferrofluid of nanostructured magnetite-maghemite particles as precursor solution. During the growth of the films the following parameters were controlled: number of dips of the substrates, dip velocity of the substrates and drying times. The films were characterized by Atomic Force Microscopy, Scanning Elelectron Microscopy, four-point method for resistance measurement, Room Temperature Mössbauer Spectroscopy and Hall effect. Mössbauer measurements showed the presence of a sextet attributed to maghemite (γ-Fe{sub 2}O{sub 3}) and two doublets attributed to superparamagnetic magnetite (Fe{sub 3}O{sub 4}), indicating a distribution of oxidation states of the iron as well as a particle size distribution of the magnetic phases in the films. Atomic force microscopy measurements showed that the films cover quasi uniformly the substrates, existing in them some pores with sub-micron size. Scanning Electron Microscopy measurements showed a uniform structure in the films, with spherical particles with size around 10 nm. Voltage versus current measurements showed an ohmic response of the films for currents between 0 and 100 nA. On the other hand, Hall effect measurements showed a nonlinear response of the Hall voltage with the magnetic flux density applied perpendicular to the plane of the films, however the response is fairly linear for magnetic flux densities between 0.15 and 0.35 T approximately. The results suggest that the films are promising for application as magnetic flux density sensors.

  10. Epitaxial thin film growth and properties of unconventional oxide superconductors. Cuprates and cobaltates

    International Nuclear Information System (INIS)

    Krockenberger, Y.

    2006-01-01

    The discovery of high-temperature superconductors has strongly driven the development of suited thin film fabrication methods of complex oxides. One way is the adaptation of molecular beam epitaxy (MBE) for the growth of oxide materials. Another approach is the use of pulsed laser deposition (PLD) which has the advantage of good stoichiometry transfer from target to the substrate. Both techniques are used within this thesis. Epitaxial thin films of new materials are of course needed for future applications. In addition, the controlled synthesis of thin film matter which can be formed far away from thermal equilibrium allows for the investigation of fundamental physical materials properties. (orig.)

  11. Epitaxial thin film growth and properties of unconventional oxide superconductors. Cuprates and cobaltates

    Energy Technology Data Exchange (ETDEWEB)

    Krockenberger, Y.

    2006-07-01

    The discovery of high-temperature superconductors has strongly driven the development of suited thin film fabrication methods of complex oxides. One way is the adaptation of molecular beam epitaxy (MBE) for the growth of oxide materials. Another approach is the use of pulsed laser deposition (PLD) which has the advantage of good stoichiometry transfer from target to the substrate. Both techniques are used within this thesis. Epitaxial thin films of new materials are of course needed for future applications. In addition, the controlled synthesis of thin film matter which can be formed far away from thermal equilibrium allows for the investigation of fundamental physical materials properties. (orig.)

  12. Epitaxial growth of textured YBa2Cu3O7-δ films on silver

    International Nuclear Information System (INIS)

    Liu Dan-Min; Liu Wei-Peng; Suo Hong-Li; Zhou Mei-Ling

    2005-01-01

    YBa 2 Cu 3 O 7-δ (YBCO) films were deposited on (100), (110) and (111) oriented silver single crystals and {100} left angle 100 right angle, {110} left angle 211 right angle, {110} left angle 100 right angle +{110} left angle 011 right angle {110} left angle 011 right angle and {012} left angle 100 right angle textured Ag substrates using pulsed laser deposition. The relationship between the epitaxial growth YBCO film and silver substrate has been determined. It is shown that among polycrystalline Ag substrates, {110} left angle 011 right angle textured tape is suitable for the deposition of YBCO thin films having strong texture. (orig.)

  13. A stochastic model of solid state thin film deposition: Application to chalcopyrite growth

    Directory of Open Access Journals (Sweden)

    Robert J. Lovelett

    2016-04-01

    Full Text Available Developing high fidelity quantitative models of solid state reaction systems can be challenging, especially in deposition systems where, in addition to the multiple competing processes occurring simultaneously, the solid interacts with its atmosphere. In this work, we develop a model for the growth of a thin solid film where species from the atmosphere adsorb, diffuse, and react with the film. The model is mesoscale and describes an entire film with thickness on the order of microns. Because it is stochastic, the model allows us to examine inhomogeneities and agglomerations that would be impossible to characterize with deterministic methods. We demonstrate the modeling approach with the example of chalcopyrite Cu(InGa(SeS2 thin film growth via precursor reaction, which is a common industrial method for fabricating thin film photovoltaic modules. The model is used to understand how and why through-film variation in the composition of Cu(InGa(SeS2 thin films arises and persists. We believe that the model will be valuable as an effective quantitative description of many other materials systems used in semiconductors, energy storage, and other fast-growing industries.

  14. Optimized growth conditions of epitaxial SnSe films grown by pulsed laser deposition

    Science.gov (United States)

    Hara, Takamitsu; Fujishiro, Hiroyuki; Naito, Tomoyuki; Ito, Akihiko; Goto, Takashi

    2017-12-01

    We have grown epitaxial tin monoselenide (SnSe) films on MgO or SrTiO3 (STO) substrates by pulsed laser deposition (PLD) at T s = 473 or 573 K, and investigated the optimized growth condition in terms of crystal orientation, crystallinity, and electrical resistivity. For the PLD procedure, a SnSe x (x = 1.0–1.6) target containing excess Se was used to compensate for the vaporization of Se. The crystal orientation and crystallinity of the SnSe films changed depending on the growth conditions, and the magnitude of the electrical resistivity ρ of the films was closely related to the crystalline nature. The SnSe film grown on the MgO substrate at T s = 573 K using the target with x = 1.4 was the most highly a-axis-oriented and highly crystalized among all of the films investigated in this study. However, the ρ of the film in the bc-plane was about one order of magnitude larger than those of the reported single crystal and the a-axis-oriented crystalline sample fabricated by spark plasma sintering. This larger ρ was suggested to result from the lattice mismatch and/or a small amount of nonstoichiometry in the film.

  15. Multi-Directional Growth of Aligned Carbon Nanotubes Over Catalyst Film Prepared by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Zhou Kai

    2010-01-01

    Full Text Available Abstract The structure of vertically aligned carbon nanotubes (CNTs severely depends on the properties of pre-prepared catalyst films. Aiming for the preparation of precisely controlled catalyst film, atomic layer deposition (ALD was employed to deposit uniform Fe2O3 film for the growth of CNT arrays on planar substrate surfaces as well as the curved ones. Iron acetylacetonate and ozone were introduced into the reactor alternately as precursors to realize the formation of catalyst films. By varying the deposition cycles, uniform and smooth Fe2O3 catalyst films with different thicknesses were obtained on Si/SiO2 substrate, which supported the growth of highly oriented few-walled CNT arrays. Utilizing the advantage of ALD process in coating non-planar surfaces, uniform catalyst films can also be successfully deposited onto quartz fibers. Aligned few-walled CNTs can be grafted on the quartz fibers, and they self-organized into a leaf-shaped structure due to the curved surface morphology. The growth of aligned CNTs on non-planar surfaces holds promise in constructing hierarchical CNT architectures in future.

  16. Epitaxial growth and properties of YBaCuO thin films

    International Nuclear Information System (INIS)

    Geerk, J.; Linker, G.; Meyer, O.

    1989-08-01

    The growth quality of YBaCuO thin films deposited by sputtering on different substrates (Al 2 O 3 , MgO, SrTiO 3 , Zr(Y)O 2 ) has been studied by X-ray diffraction and channeling experiments as a function of the deposition temperature. Besides the substrate orientation, the substrate temperature is the parameter determining whether films grow in c-, a-, (110) or mixed directions. Epitaxial growth correlates with high critical current values in the films of up to 5.5x10 6 A/cm 2 at 77 K. Ultrathin films with thicknesses down to 2 nm were grown revealing three-dimensional superconducting behaviour. Films on (100) SrTiO 3 of 9 nm thickness and below are partially strained indicating commensurate growth. From the analysis of the surface disorder 1 displaced Ba atom per Ba 2 Y row was obtained indicating that the disordered layer thickness is about 0.6 nm. Tunnel junctions fabricated on these films reveal gap-like structures near ±16 mV and ±30 mV. (orig.) [de

  17. Scaling of elongation transition thickness during thin-film growth on weakly interacting substrates

    Science.gov (United States)

    Lü, B.; Souqui, L.; Elofsson, V.; Sarakinos, K.

    2017-08-01

    The elongation transition thickness ( θElong) is a central concept in the theoretical description of thin-film growth dynamics on weakly interacting substrates via scaling relations of θElong with respect to rates of key atomistic film-forming processes. To date, these scaling laws have only been confirmed quantitatively by simulations, while experimental proof has been left ambiguous as it has not been possible to measure θElong. Here, we present a method for determining experimentally θElong for Ag films growing on amorphous SiO2: an archetypical weakly interacting film/substrate system. Our results confirm the theoretically predicted θElong scaling behavior, which then allow us to calculate the rates of adatom diffusion and island coalescence completion, in good agreement with the literature. The methodology presented herein casts the foundation for studying growth dynamics and cataloging atomistic-process rates for a wide range of weakly interacting film/substrate systems. This may provide insights into directed growth of metal films with a well-controlled morphology and interfacial structure on 2D crystals—including graphene and MoS2—for catalytic and nanoelectronic applications.

  18. Modelling the growth of ZnO thin films by PVD methods and the effects of post-annealing.

    Science.gov (United States)

    Blackwell, Sabrina; Smith, Roger; Kenny, Steven D; Walls, John M; Sanz-Navarro, Carlos F

    2013-04-03

    deposited film and therefore resulting in more stacking faults and phase boundaries. The methods used allow analysis of key mechanisms that occur during the growth process and give hints as to the optimum conditions under which complete crystalline layers can form.

  19. Transport, mechanical and global migration data of multilayer copolyamide nanocomposite films with different layouts

    OpenAIRE

    Scarfato, P.; Garofalo, E.; Di Maio, L.; Incarnato, L.

    2017-01-01

    Transport, mechanical and global migration data concern multilayer food packaging films with different layouts, all incorporating a layered silicate/polyamide nanocomposite as oxygen barrier layer, and a low-density polyethylene (LDPE) as moisture resistant layer in direct contact with food. The data are related to ?Tuning of co-extrusion processing conditions and film layout to optimize the performances of PA/PE multilayer nanocomposite films for food packaging? by?Garofalo et al. (2017) [1]...

  20. Setup for in situ X-ray diffraction studies of thin film growth by magnetron sputtering

    CERN Document Server

    Ellmer, K; Weiss, V; Rossner, H

    2001-01-01

    A novel method is described for the in situ-investigation of nucleation and growth of thin films during magnetron sputtering. Energy dispersive X-ray diffraction with synchrotron light is used for the structural analysis during film growth. An in situ-magnetron sputtering chamber was constructed and installed at a synchrotron radiation beam line with a bending magnet. The white synchrotron light (1-70 keV) passes the sputtering chamber through Kapton windows and hits one of the substrates on a four-fold sample holder. The diffracted beam, observed under a fixed diffraction angle between 3 deg. and 10 deg., is energy analyzed by a high purity Ge-detector. The in situ-EDXRD setup is demonstrated for the growth of tin-doped indium oxide (ITO) films prepared by reactive magnetron sputtering from a metallic target.

  1. Growth of gold nanoclusters and nanocrystals induced by lysozyme protein in thin film conformation

    Science.gov (United States)

    Bhowal, Ashim Chandra; Kundu, Sarathi

    2016-08-01

    Structures and growth behavior of gold nanoclusters and nanocrystals have been explored on thin films of globular protein lysozyme by using UV-vis and photoluminescence spectroscopy, X-ray diffraction (XRD) and atomic force microscopy (AFM). A simple and one-step environment friendly method has been used to grow nanocrystals on protein surface from HAuCl4 solution. It has been found that if different interaction times are provided between lysozyme films and HAuCl4 solution, then initially formed tiny gold nanoclusters on protein surface transform into nanocrystals with the passage of time. XRD analysis shows the formation of faced-centered cubic lattice along (1 1 1) crystalline direction and AFM images confirm the presence of circular, rod-like, triangular and hexagonal crystal structures. Langmuir-like growth behavior has been identified for both the gold nanoclusters and nanocrystals formation induced by the lysozyme films, however, nanocrystal growth is relatively slower than nanocluster.

  2. Mechanical and water barrier properties of agar/κ-carrageenan/konjac glucomannan ternary blend biohydrogel films.

    Science.gov (United States)

    Rhim, Jong-Whan; Wang, Long-Feng

    2013-07-01

    Multicomponent hydrogel films composed of agar, κ-carrageenan, konjac glucomannan powder, and nanoclay (Cloisite(®) 30B) were prepared and their mechanical and water barrier properties such as water vapor permeability (WVP), water contact angle (CA), water solubility (WS), water uptake ratio (WUR), water vapor uptake ratio (WVUR) were determined. Mechanical, water vapor barrier, and water resistance properties of the ternary blend film exhibited middle range of individual component films, however, they increased significantly after formation of nanocomposite with the clay. Especially, the water holding capacity of the ternary blend biopolymer films increased tremendously, from 800% to 1681% of WUR for agar and κ-carrageenan films up to 5118% and 5488% of WUR for the ternary blend and ternary blend nanocomposite films, respectively. Water vapor adsorption behavior of films was also tested by water vapor adsorption kinetics and water vapor adsorption isotherms test. Preliminary test result for fresh spinach packaging revealed that the ternary blend biohydrogel films had a high potential for the use as an antifogging film for packaging highly respiring agricultural produce. In addition, the ternary blend nanocomposite film showed an antimicrobial activity against Gram-positive bacteria, Listeria monocytogenes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Preparation of reduced graphene oxide/gelatin composite films with reinforced mechanical strength

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenchao [School of Science, Tianjin University, Tianjin (China); Wang, Zhipeng [School of Science, Tianjin University, Tianjin (China); School of Chemical Engineering, Tianjin University, Tianjin (China); Liu, Yu; Li, Nan [School of Science, Tianjin University, Tianjin (China); Wang, Wei [School of Chemical Engineering, Tianjin University, Tianjin (China); Gao, Jianping, E-mail: jianpingg@eyou.com [School of Chemical Engineering, Tianjin University, Tianjin (China)

    2012-09-15

    Highlights: ► We used and compared different proportion of gelatin and chitosan as reducing agents. ► The mechanical properties of the films are investigated, especially the wet films. ► The cell toxicity of the composite films as biomaterial is carried out. ► The water absorption capabilities of the composite films also studied. -- Abstract: Graphene oxide (GO) was reduced by chitosan/gelatin solution and added to gelatin (Gel) to fabricate reduced graphene oxide/gelatin (RGO/Gel) films by a solvent-casting method using genipin as cross-linking agent. The structure and properties of the films were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and UV–vis spectroscopy. The addition of RGO increased the tensile strength of the RGO/Gel films in both dry and wet states, but decreased their elongation at break. The incorperation of RGO also decreased the swelling ability of the films in water. Cell cultures were carried out in order to test the cytotoxicity of the films. The cells grew and reproduced well on the RGO/Gel films, indicating that the addition of RGO has no negative effect on the compatibility of the gelatin. Therefore, the reduced graphene oxide/gelatin composite is a promising biomaterial with excellent mechanical properties and good cell compatibility.

  4. CdS sintered films: growth and characteristics

    International Nuclear Information System (INIS)

    Sharma, Monika; Kumar, Sushil; Sharma, L.M.; Sharma, T.P.; Husain, M.

    2004-01-01

    Cadmium sulphide finds extensive applications in a variety of optoelectronic devices. CdS, with a band gap of 2.43 eV, is a suitable window material in heterojunction solar cells that employ CdTe, Cu 2 S or CuInSe 2 as an absorber. Polycrystalline films of CdS, thickness ∼15 μm, were grown onto chemically clean and optically plane glass substrates by sintering process. A 10 min sintering time and 500 deg. C sintering temperature were found to be optimum. As deposited films were characterized through optical, structural and electrical transport properties using optical reflection spectroscopy, X-ray diffractometry and I-V characteristics techniques

  5. Seeding of polymer substrates for nanocrystalline diamond film growth

    Czech Academy of Sciences Publication Activity Database

    Kromka, Alexander; Babchenko, Oleg; Kozak, Halyna; Hruška, Karel; Rezek, Bohuslav; Ledinský, Martin; Potměšil, Jiří; Michalka, M.; Vaněček, Milan

    2009-01-01

    Roč. 18, 5-8 (2009), s. 734-739 ISSN 0925-9635 R&D Projects: GA AV ČR KAN400100701; GA AV ČR KAN400100652 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanocrystalline diamond films * chemical vapor deposition * polymer * sscanning electron spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.822, year: 2009

  6. Growth and Characterization of Epitaxial Piezoelectric and Semiconductor Films.

    Science.gov (United States)

    1980-07-01

    better control of the process, ond unliorm nucleation have now been achieved. Lithia as a foreign atom in zinc oxide shows 6 amphoteric behavior. It...research are given in the appendices. k * 3 2.0 BACKGROUND Zinc oxide and aluminum nitride have immense potential for use in the electronics industry...Oxygen defects make it difficult to grow a stoichiometric crystal. Zinc oxide films are generally grown under low oxygen partial pressure in the

  7. Growth, Characterization and Device Development in Monocrystalline Diamond Films

    Science.gov (United States)

    1991-09-30

    IMPact Avalanche Transit-Time (IM- A. SiC PATI’) diode. Bipolar Junction Transistor ( BJT ) operation Silicon carbide is the only compound in the SiC...include LED’s, thermistors, MESFET’s, bipolar and position of thin films and the associated technologies of impurity heterojunction transistors , and...Effect Transistor developed to the point wlere high performance devices (MESFET), the IMPact Avalanche Transit-Time (IMPATT) diode, can be easily

  8. Starch behaviors and mechanical properties of starch blend films with different plasticizers.

    Science.gov (United States)

    Nguyen Vu, Hoang Phuong; Lumdubwong, Namfone

    2016-12-10

    The main objective of the study was to gain insight into structural and mechanical starch behaviors of the plasticized starch blend films. Mechanical properties and starch behaviors of cassava (CS)/and mungbean (MB) (50/50, w/w) starch blend films containing glycerol (Gly) or sorbitol (Sor) at 33% weight content were investigated. It was found that tensile strength TS and %E of the Gly-CSMB films were similar to those of MB films; but%E of all Sor-films was identical. TS of plasticized films increased when AM content and crystallinity increased. When Sor was substituted for Gly, crystallinity of starch films and their TS increased. The CSMB and MB films had somewhat a similar molecular profile and comparable mechanical properties. Therefore, it was proposed the starch molecular profile containing amylopectin with high M¯w, low M¯w of amylose, and the small size of intermediates may impart the high TS and%E of starch films. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. AFM investigations of the morphology features and local mechanical properties of HTS YBCO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Soifer, Yakov M.; Verdyan, Armen; Lapsker, Igor; Azoulay, Jacob

    2004-08-01

    In the paper presented here the application of the atomic force microscope (AFM) is considered for evaluation of hardness and Young's modulus of high T{sub c} superconducting YBCO thin films of different thickness (from 0.05 to 1 {mu}m) grown on unbuffered SrTiO{sub 3} (film I) and on sapphire with a buffer layer of CeO{sub 2} (film II). The best film features a transition temperature T{sub c} of 90 K, critical current density J{sub c} (H=0) of 3 x 10{sup 7} A/cm{sup 2} at 4.2 K and 2 x 10{sup 6} A/cm{sup 2} at 77 K. The relationship between mechanical properties and microstructure of these films was investigated. It was found that all the films comprised well-defined Cu-rich precipitates of different size and with different density on their surface. For both type of films the hardness was measured to be in the range of 12-18 GPa. The Young's modulus of the films was about 180-200 GPa. The nanoindentation and nanoscratching measurements showed that the mechanical strength of the films studied was determined mainly by mechanical failure and surface defects (secondary phases)

  10. Growth of vertically aligned ZnO nanorods using textured ZnO films

    Directory of Open Access Journals (Sweden)

    Meléndrez Manuel

    2011-01-01

    Full Text Available Abstract A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100 substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.

  11. Growth of vertically aligned ZnO nanorods using textured ZnO films

    Science.gov (United States)

    Solís-Pomar, Francisco; Martínez, Eduardo; Meléndrez, Manuel F.; Pérez-Tijerina, Eduardo

    2011-09-01

    A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD) is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100) substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells.

  12. Mechanical and thermal properties of irradiated films based on Tilapia (Oreochromis niloticus) proteins

    International Nuclear Information System (INIS)

    Sabato, S.F.; Nakamurakare, N.; Sobral, P.J.A.

    2007-01-01

    Proteins are considered potential material in natural films as alternative to traditional packaging. When gamma radiation is applied to protein film forming solution it resulted in an improvement in mechanical properties of whey protein films. The objective of this work was the characterization of mechanical and thermal properties of irradiated films based on muscle proteins from Nile Tilapia (Oreochromis niloticus). The films were prepared according to a casting technique with two levels of plasticizer: 25% and 45% glycerol and irradiated in electron accelerator type Radiation Dynamics, 0.550 MeV at dose range from 0 to 200 kGy. Thermal properties and mechanical properties were determined using a differential scanning calorimeter and a texture analyzer, respectively. Radiation from electron beam caused a slightly increase on its tensile strength characteristic at 100 kGy, while elongation value at this dose had no reduction

  13. Mechanical and thermal properties of irradiated films based on Tilapia (Oreochromis niloticus) proteins

    Energy Technology Data Exchange (ETDEWEB)

    Sabato, S.F. [Radiation Technology Center, IPEN-CNEN/SP, Av. Lineu Prestes 2242, 05508 900 Sao Paulo, SP (Brazil)], E-mail: sfsabato@ipen.br; Nakamurakare, N.; Sobral, P.J.A. [Food Engineering Department, ZEA/FZEA/USP, Av. Duque de Caxias Norte 225, 13635 900 Pirassununga, SP (Brazil)

    2007-11-15

    Proteins are considered potential material in natural films as alternative to traditional packaging. When gamma radiation is applied to protein film forming solution it resulted in an improvement in mechanical properties of whey protein films. The objective of this work was the characterization of mechanical and thermal properties of irradiated films based on muscle proteins from Nile Tilapia (Oreochromis niloticus). The films were prepared according to a casting technique with two levels of plasticizer: 25% and 45% glycerol and irradiated in electron accelerator type Radiation Dynamics, 0.550 MeV at dose range from 0 to 200 kGy. Thermal properties and mechanical properties were determined using a differential scanning calorimeter and a texture analyzer, respectively. Radiation from electron beam caused a slightly increase on its tensile strength characteristic at 100 kGy, while elongation value at this dose had no reduction.

  14. Introducing Viewpoints of Mechanics into Basic Growth Analysis (1) : Three Aspects of Growth Mechanics compared with Three Law of Motion

    OpenAIRE

    Shimojo, Masataka; Ikeda, Kentaro; Asano, Yoki; Ishiwaka, Reiko; Sato, Hiroyuki; Nakano, Yutaka; Tobisa, Manabu; Oba, Noriko; Eguchi, Minako; Masuda, Yasuhisa

    2006-01-01

    This study was conducted to analyze growth phenomena by introducing mechanical viewpoints into basic growth analysis. Relating weight (W), absolute growth rate (AGR) and growth acceleration (GA) suggested that (AGR)^2, which was described as the product of W and GA, looked like force involved in the growth of an animal or a plant. This might be due to the resemblance to the second law of Newton’s three laws of motion, where the product of mass and acceleration is related with force to an obje...

  15. Thermal and Mechanical Properties of Poly(butylene succinate Films Reinforced with Silica

    Directory of Open Access Journals (Sweden)

    Sangviroon Nanthaporn

    2015-01-01

    Full Text Available In recent year, bioplastics have become more popular resulting from the growing concerns on environmental issues and the rising fossil fuel price. However, their applications were limited by its mechanical and thermal properties. The aim of this research is thus to improve mechanical and thermal properties of PBS bioplastic films by reinforcing with silica. Due to the poor interfacial interaction between the PBS matrix and silica, glycidyl methacrylate grafted poly(butylene succinate (PBS-g-GMA was used as a compatibilizer in order to improve the interaction between bioplastic films and filler. PBS-g-GMA was prepared in a twin-screw extruder and analyzed by the FTIR spectrometer. PBS and silica were then mixed in a twin-screw extruder and processed into films by a chill-roll cast extruder. The effects of silica loading on thermal and mechanical properties of the prepared bioplastic films were investigated. It was found that the mechanical properties of PBS/silica composite films were improved when 1%wt of silica was added. However, the mechanical properties decreased with increasing silica loading due to the agglomeration of silica particles. The results also show that the silica/PBS films with PBS-g-GMA possessed improved mechanical properties over the films without the compatibilizer.

  16. Drying of latex films and coatings: Reconsidering the fundamental mechanisms

    DEFF Research Database (Denmark)

    Kiil, Søren

    2006-01-01

    to previous model studies, but in agreement with observations, simulations suggest that during the falling rate period of the drying process of a latex film, a porous skin of partly coalesced latex particles is indeed formed, which limits transport of water vapour from the receding air-liquid interphase...... to the surface of the film. The value of the effective diffusion coefficient of water vapour in the dry and partly coalesced layer (7 x 10(-7) m(2)/s at 19-24 degrees C), the adjustable parameter of the model for the falling rate period, was found to be independent of initial wet film thickness (89-1322 mu m...... film thickness, initial polymer volume concentration, and air flow velocity are simulated and analysed using the new model. (c) 2006 Elsevier B.V. All rights reserved....

  17. Mechanical stretch influence on lifetime of dielectric elastomer films

    Science.gov (United States)

    Iannarelli, A.; Niasar, M. Ghaffarian

    2017-04-01

    Film pre-stretching is a widely adopted solution to improve dielectric strength of the DEA systems. However, to date, long term reliability of this solution has not been investigated. In this work it is explored how the dielectric elastomer lifetime is affected by film pre-stretching. The dielectric loss of soft polydimethylsiloxane (PDMS) films is studied for different stretch ratios by measuring tanδ. Additionally, time-to-breakdown was measured at DC electric stress for different stretch ratios. For this purpose, accelerated life test (ALT) were performed. The results obtained are compared with non-pre-stretched samples. This study suggests that no additional dielectric losses are caused by film stretching up to 80% of original dimensions.

  18. Smooth growth of organic semiconductor films on graphene for high-efficiency electronics.

    Science.gov (United States)

    Hlawacek, Gregor; Khokhar, Fawad S; van Gastel, Raoul; Poelsema, Bene; Teichert, Christian

    2011-02-09

    High-quality thin films of conjugated molecules with smooth interfaces are important to assist the advent of organic electronics. Here, we report on the layer-by-layer growth of the organic semiconductor molecule p-sexiphenyl (6P) on the transparent electrode material graphene. Low energy electron microscopy and micro low energy electron diffraction reveal the morphological and structural evolution of the thin film. The layer-by-layer growth of 6P on graphene proceeds by subsequent adding of {111} layers.

  19. Mechanistic Insights into Growth of Surface-Mounted Metal-Organic Framework Films Resolved by Infrared (Nano-) Spectroscopy

    NARCIS (Netherlands)

    Delen, Guusje; Ristanovic, Zoran|info:eu-repo/dai/nl/328233005; Mandemaker, Laurens D. B.; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2018-01-01

    Control over assembly, orientation, and defect-free growth of metal-organic framework (MOF) films is crucial for their future applications. A layer-by-layer approach is considered a suitable method to synthesize highly oriented films of numerous MOF topologies, but the initial stages of the film

  20. Non-coherent growth patches in pseudomorphic films: Unusual strain relief in electrodeposited Co on Cu(001)

    DEFF Research Database (Denmark)

    Schindler, W.; Koop, T.; Kazimirov, A.

    2000-01-01

    of electrodeposited films is in contrast to current belief of film relaxation. Moreover, a tetragonal distortion of the fee Co unit cell in the orthomorphic growth regime indicates residual strain in films of up to at least 100 monolayers thickness. (C) 2000 Elsevier Science B.V. All rights reserved....

  1. Physical and mechanical testing of essential oil-embedded cellulose ester films

    Science.gov (United States)

    Polymer films made from cellulose esters are useful for embedding plant essential oils, either for food packaging or air freshener applications. Studies and testing were done on the physical and mechanical properties of cellulose ester-based films incorporating essential oils (EO) from lemongrass (C...

  2. On the oxidation mechanism of microcrystalline silicon thin films studied by Fourier transform infrared spectroscopy

    NARCIS (Netherlands)

    Bronneberg, A. C.; Smets, A. H. M.; Creatore, M.; M. C. M. van de Sanden,

    2011-01-01

    Insight into the oxidation mechanism of microcrystalline silicon thin films has been obtained by means of Fourier transform infrared spectroscopy. The films were deposited by using the expanding thermal plasma and their oxidation upon air exposure was followed in time. Transmission spectra were

  3. Growth and transport properties of thin Co-based Heusler films; Wachstum und Transporteigenschaften duenner Co-basierter Heusler-Filme

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Horst

    2010-07-01

    During this work, thin films of Co-based Heusler compounds were deposited under optimized conditions, and their structural, magnetic, and transport properties were investigated. The growth of the thin film samples was accomplished by two different methods. At first Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al and Co{sub 2}FeSi were deposited by sputter deposition from stoichiometric targets. This is considered the standard technique for the preparation of thin Heusler films. Also for the compounds investigated here it resulted in samples with a high degree of L2{sub 1} ordering. An excess of Fe atoms on Si sites was discovered by a detailed X-ray analysis in conjunction with NMR spectroscopy. The choice of different substrates allowed the adjustment of the growth direction. On the other hand, bulk magnetometry revealed that these sputter deposited films exhibit only a reduced magnetic moment, which is an indication of a reduced spin asymmetry at the Fermi level. One source of this problem seems to be a high residual gas pressure, which leads to an increased sample contamination. To improve this situation, a pulsed laser deposition system was constructed and put into operation. The resulting film growth under ultra-high vacuum conditions led to a further improvement of the short-range crystallographic ordering and a clear enhancement of the magnetic properties. The additional use of a metallic buffer layer resulted in samples with a smooth surface. This opens the door for a number of further analytical experiments, such as tunneling spectroscopy or Brillouin light scattering. After this successful demonstration of this growth technique, an additional method for the flexible variation of the film stoichiometry was implemented. In this work, this method was successfully applied in the deposition of Co{sub 2}Mn{sub 1-x}Fe{sub x}Si films. All samples in this series show a high degree of atomic ordering. Their magnetization values are compatible with the Slater-Pauling rule for

  4. Hair Growth Promotion Activity and Its Mechanism of Polygonum multiflorum

    Directory of Open Access Journals (Sweden)

    Yunfei Li

    2015-01-01

    Full Text Available Polygonum multiflorum Radix (PMR has long history in hair growth promotion and hair coloring in clinical applications. However, several crucial problems in its clinic usage and mechanisms are still unsolved or lack scientific evidences. In this research, C57BL/6J mice were used to investigate hair growth promotion activity and possible mechanism of PMR and Polygonum multiflorum Radix Preparata (PMRP. Hair growth promotion activities were investigated by hair length, hair covered skin ratio, the number of follicles, and hair color. Regulation effects of several cytokines involved in the hair growth procedure were tested, such as fibroblast growth factor (FGF-7, Sonic Hedgehog (SHH, β-catenin, insulin-like growth factor-1 (IGF-1, and hepatocyte growth factor (HGF. Oral PMR groups had higher hair covered skin ratio (100 ± 0.00% than oral PMRP groups (48%~88%. However, topical usage of PMRP had about 90% hair covered skin ratio. Both oral administration of PMR and topically given PMRP showed hair growth promotion activities. PMR was considered to be more suitable for oral administration, while PMRP showed greater effects in external use. The hair growth promotion effect of oral PMR was most probably mediated by the expression of FGF-7, while topical PMRP promoted hair growth by the stimulation of SHH expression.

  5. Hair Growth Promotion Activity and Its Mechanism of Polygonum multiflorum

    Science.gov (United States)

    Li, Yunfei; Han, Mingnuan; He, Yanran; Zhao, Ronghua

    2015-01-01

    Polygonum multiflorum Radix (PMR) has long history in hair growth promotion and hair coloring in clinical applications. However, several crucial problems in its clinic usage and mechanisms are still unsolved or lack scientific evidences. In this research, C57BL/6J mice were used to investigate hair growth promotion activity and possible mechanism of PMR and Polygonum multiflorum Radix Preparata (PMRP). Hair growth promotion activities were investigated by hair length, hair covered skin ratio, the number of follicles, and hair color. Regulation effects of several cytokines involved in the hair growth procedure were tested, such as fibroblast growth factor (FGF-7), Sonic Hedgehog (SHH), β-catenin, insulin-like growth factor-1 (IGF-1), and hepatocyte growth factor (HGF). Oral PMR groups had higher hair covered skin ratio (100 ± 0.00%) than oral PMRP groups (48%~88%). However, topical usage of PMRP had about 90% hair covered skin ratio. Both oral administration of PMR and topically given PMRP showed hair growth promotion activities. PMR was considered to be more suitable for oral administration, while PMRP showed greater effects in external use. The hair growth promotion effect of oral PMR was most probably mediated by the expression of FGF-7, while topical PMRP promoted hair growth by the stimulation of SHH expression. PMID:26294926

  6. Elucidation of the Fundamental Mechanisms of Diamond Film Growth

    National Research Council Canada - National Science Library

    Blumenthal, Rik

    1998-01-01

    .... The technique is based on the release of a short pulse of noble gas into the near vacuum. As the pulse expands, the molecular and atomic species present in the plasma are swept into the rapidly expanding noble gas pulse...

  7. Mechanism of large optical nonlinearity in gold nanoparticle films.

    Science.gov (United States)

    Mirza, I; McCloskey, D; Blau, W J; Lunney, J G

    2018-04-01

    The Z-scan technique, using femtosecond (fs) laser pulses at 1480 nm laser pulses, was used to measure the nonlinear optical properties of gold (Au) nanoparticle (NP) films made by both nanosecond (ns) and fs pulsed laser deposition (PLD) in vacuum. At irradiance levels of 1×10 12   Wm -2 , the ns-PLD films displayed induced absorption with β=4×10 -5   mW -1 , and a negative lensing effect with n 2 =-4.7×10 -11   m 2  W -1 with somewhat smaller values for the fs-PLD films. These values of n 2 imply an unphysically large change in the real part of the refractive index, demonstrating the need to take account of nonlinear changes of the Fresnel coefficients and multiple beam interference in Z-scan measurements on nanoscale films. Following this approach, the Z-scan observations were analyzed to determine the effective complex refractive index of the NP film at high irradiance. It appears that at high irradiance the NP film behaves as a metal, while at low irradiance it behaves as a low-loss dielectric. Thus, it is conjectured that, for high irradiance near the waist of the Z-scan laser beam, laser driven electron tunneling between NPs gives rise to metal-like optical behavior.

  8. Growth, morphology, and conductivity in semimetallic/metallic films on Si(001)

    Energy Technology Data Exchange (ETDEWEB)

    Jnawali, Giriraj

    2009-06-09

    This dissertation deals with the study of epitaxial growth of semimetallic (Bi) and metallic (Ag) films on Si(001) as well as in situ electrical transport study of those films via surface manipulation. The focus of the transport measurements is to study the influence of the surface morphology or structure on the resistance of the film. In spite of the large lattice mismatch and different lattice geometry, it is possible to grow epitaxial Bi(111) films on Si(001) substrates, which are surprisingly smooth, relaxed and almost free of defects. Due to the two-fold symmetry of the substrates, the Bi(111) film is composed of crystallites rotated by 90 with respect to each other. Annealing of 6 nm film from 150 K to 450 K enables the formation of a periodic interfacial misfit dislocations, which accommodates a remaining lattice mismatch of 2.3 %. The surface/interface roughness and the bulk defect density of the film found to be extremely low, indicating the high crystalline quality of the film with atomically smooth surface and abrupt interface. Similar to the Bi films, Ag grows in a (111) orientation on Si(001) with two 90 rotated domains. The remaining strain of 2.2 % (tensile) is accommodated by the formation of an ordered network of dislocations. The Ag film exhibits atomically smooth surface. Those Bi films and Ag films were used as model systems to study the influence of the surface morphology on the electrical resistance. Surprisingly, all the Bi films (3-170 nm thicknesses) have shown an anomalous behavior of conductance with temperature and thickness. As in the case of doped semiconductor, the conductance increases exponentially from 150 K to 300 K and saturates at 350 K before finally decreasing with temperature. In situ measurements of the resistance during additional Bi deposition on the smooth Bi(111) films exhibit a square root dependent with coverage after a linear increase at very low coverage (1 % of a BL). During additional deposition of Bi, carriers are

  9. Mechanisms regulating skeletal muscle growth and atrophy.

    Science.gov (United States)

    Schiaffino, Stefano; Dyar, Kenneth A; Ciciliot, Stefano; Blaauw, Bert; Sandri, Marco

    2013-09-01

    Skeletal muscle mass increases during postnatal development through a process of hypertrophy, i.e. enlargement of individual muscle fibers, and a similar process may be induced in adult skeletal muscle in response to contractile activity, such as strength exercise, and specific hormones, such as androgens and β-adrenergic agonists. Muscle hypertrophy occurs when the overall rates of protein synthesis exceed the rates of protein degradation. Two major signaling pathways control protein synthesis, the IGF1-Akt-mTOR pathway, acting as a positive regulator, and the myostatin-Smad2/3 pathway, acting as a negative regulator, and additional pathways have recently been identified. Proliferation and fusion of satellite cells, leading to an increase in the number of myonuclei, may also contribute to muscle growth during early but not late stages of postnatal development and in some forms of muscle hypertrophy in the adult. Muscle atrophy occurs when protein degradation rates exceed protein synthesis, and may be induced in adult skeletal muscle in a variety of conditions, including starvation, denervation, cancer cachexia, heart failure and aging. Two major protein degradation pathways, the proteasomal and the autophagic-lysosomal pathways, are activated during muscle atrophy and variably contribute to the loss of muscle mass. These pathways involve a variety of atrophy-related genes or atrogenes, which are controlled by specific transcription factors, such as FoxO3, which is negatively regulated by Akt, and NF-κB, which is activated by inflammatory cytokines. © 2013 The Authors Journal compilation © 2013 FEBS.

  10. The correlation between mechanical stress and magnetic anisotropy in ultrathin films

    International Nuclear Information System (INIS)

    Sander, D.

    1999-01-01

    The impact of stress-driven structural transitions and of film strain on the magnetic properties of nm ferromagnetic films is discussed. The stress-induced bending of film-substrate composites is analysed to derive information on film stress due to lattice mismatch or due to surface-stress effects. The magneto-elastic coupling in epitaxial films is determined directly from the magnetostrictive bending of the substrate. The combination of stress measurements with magnetic investigations by the magneto-optical Kerr effect (MOKE) reveals the modification of the magnetic anisotropy by film stress. Stress-strain relations are derived for various epitaxial orientations to facilitate the analysis of the substrate curvature. Biaxial film stress and magneto-elastic coupling coefficients are measured in epitaxial Fe films in situ on W single-crystal substrates. Tremendous film stress of more than 10 GPa is measured in pseudomorphic Fe layers, and the important role of film stress as a driving force for the formation of misfit distortions and for inducing changes of the growth mode in monolayer thin films is presented. The direct measurement of the magneto-elastic coupling in epitaxial films proves that the magnitude and sign of the magneto-elastic coupling deviate from the respective bulk value. Even a small film strain of order 0.1% is found to induce a significant change of the effective magneto-elastic coupling coefficient. This peculiar behaviour is ascribed to a second-order strain dependence of the magneto-elastic energy density, in contrast to the linear strain dependence that is valid for bulk samples. (author)

  11. Epitaxial growth of bcc-FexCo100-x thin films on MgO(1 1 0) single-crystal substrates

    International Nuclear Information System (INIS)

    Ohtake, Mitsuru; Nishiyama, Tsutomu; Shikada, Kouhei; Kirino, Fumiyoshi; Futamoto, Masaaki

    2010-01-01

    Fe x Co 100-x (x=100, 65, 50 at%) epitaxial thin films were prepared on MgO(1 1 0) single-crystal substrates heated at 300 deg. C by ultra-high vacuum molecular beam epitaxy. The film structure and the growth mechanism are discussed. FeCo(2 1 1) films with bcc structure grow epitaxially on MgO(1 1 0) substrates with two types of variants whose orientations are rotated around the film normal by 180 deg. each other for all compositions. Fe x Co 100-x film growth follows the Volmer Weber mode. X-ray diffraction analysis indicates the out-of-plane and the in-plane lattice spacings are in agreement with the values of respective bulk Fe x Co 100-x crystals with very small errors less than ±0.4%, suggesting the strains in the films are very small. High-resolution cross-sectional transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the film at the Fe 50 Co 50 /MgO interface along the MgO[1 1-bar 0] direction. The presence of such periodical dislocations decreases the large lattice mismatch of about -17% existing at the FeCo/MgO interface along the MgO[1 1-bar 0] direction.

  12. Growth of gold nanoclusters and nanocrystals induced by lysozyme protein in thin film conformation

    Energy Technology Data Exchange (ETDEWEB)

    Bhowal, Ashim Chandra; Kundu, Sarathi, E-mail: sarathi.kundu@gmail.com

    2016-08-22

    Highlights: • Gold nanoclusters and nanocrystals form on thin film of lysozyme protein. • Nanocrystals formation is possible from mM concentration of HAuCl{sub 4}. • Both nanoclusters and nanocrystals follow Langmuir-like growth on protein surface. • Growth rate of nanocrystal is slower than nanocluster. • On protein surface nanocrystals take triangular, hexagonal and disc as shape. - Abstract: Structures and growth behavior of gold nanoclusters and nanocrystals have been explored on thin films of globular protein lysozyme by using UV–vis and photoluminescence spectroscopy, X-ray diffraction (XRD) and atomic force microscopy (AFM). A simple and one-step environment friendly method has been used to grow nanocrystals on protein surface from HAuCl{sub 4} solution. It has been found that if different interaction times are provided between lysozyme films and HAuCl{sub 4} solution, then initially formed tiny gold nanoclusters on protein surface transform into nanocrystals with the passage of time. XRD analysis shows the formation of faced-centered cubic lattice along (1 1 1) crystalline direction and AFM images confirm the presence of circular, rod-like, triangular and hexagonal crystal structures. Langmuir-like growth behavior has been identified for both the gold nanoclusters and nanocrystals formation induced by the lysozyme films, however, nanocrystal growth is relatively slower than nanocluster.

  13. Growth of gold nanoclusters and nanocrystals induced by lysozyme protein in thin film conformation

    International Nuclear Information System (INIS)

    Bhowal, Ashim Chandra; Kundu, Sarathi

    2016-01-01

    Highlights: • Gold nanoclusters and nanocrystals form on thin film of lysozyme protein. • Nanocrystals formation is possible from mM concentration of HAuCl 4 . • Both nanoclusters and nanocrystals follow Langmuir-like growth on protein surface. • Growth rate of nanocrystal is slower than nanocluster. • On protein surface nanocrystals take triangular, hexagonal and disc as shape. - Abstract: Structures and growth behavior of gold nanoclusters and nanocrystals have been explored on thin films of globular protein lysozyme by using UV–vis and photoluminescence spectroscopy, X-ray diffraction (XRD) and atomic force microscopy (AFM). A simple and one-step environment friendly method has been used to grow nanocrystals on protein surface from HAuCl 4 solution. It has been found that if different interaction times are provided between lysozyme films and HAuCl 4 solution, then initially formed tiny gold nanoclusters on protein surface transform into nanocrystals with the passage of time. XRD analysis shows the formation of faced-centered cubic lattice along (1 1 1) crystalline direction and AFM images confirm the presence of circular, rod-like, triangular and hexagonal crystal structures. Langmuir-like growth behavior has been identified for both the gold nanoclusters and nanocrystals formation induced by the lysozyme films, however, nanocrystal growth is relatively slower than nanocluster.

  14. New chemistry for the growth of first-row transition metal films by atomic layer deposition

    Science.gov (United States)

    Klesko, Joseph Peter

    Thin films containing first-row transition metals are widely used in microelectronic, photovoltaic, catalytic, and surface-coating applications. In particular, metallic films are essential for interconnects and seed, barrier, and capping layers in integrated circuitry. Traditional vapor deposition methods for film growth include PVD, CVD, or the use of plasma. However, these techniques lack the requisite precision for film growth at the nanoscale, and thus, are increasingly inadequate for many current and future applications. By contrast, ALD is the favored approach for depositing films with absolute surface conformality and thickness control on 3D architectures and in high aspect ratio features. However, the low-temperature chemical reduction of most first-row transition metal cations to their zero-valent state is very challenging due to their negative electrochemical potentials. A lack of strongly-reducing coreagents has rendered the thermal ALD of metallic films an intractable problem for many elements. Additionally, several established ALD processes for metal films are plagued by low growth rates, impurity incorporation, poor nucleation, high surface roughness, or the need for hazardous coreagents. Finally, stoichiometric control of ternary films grown by ALD is rare, but increasingly important, with emerging applications for metal borate films in catalysis and lithium ion batteries. The research herein is focused toward the development of new ALD processes for the broader application of metal, metal oxide, and metal borate thin films to future nanoscale technologies. These processes display self-limited growth and support the facile nucleation of smooth, continuous, high-purity films. Bis(trimethylsilyl) six-membered rings are employed as strongly-reducing organic coreagents for the ALD of titanium and antimony metal films. Additionally, new processes are developed for the growth of high-purity, low-resistivity cobalt and nickel metal films by exploiting the

  15. Unveiling polytype transformation assisted growth mechanism in boron carbide nanowires

    Science.gov (United States)

    Song, Ningning; Li, Xiaodong

    2018-01-01

    We demonstrate direct evidence that the lattice distortion, induced by boron carbide (BxCy) stoichiometry, assists the growth of boron carbide nanowires. The transformation between different polytypic boron carbide phases lowers the energy barrier for boron diffusion, promoting boron migration in the nanowire growth. An atomistic mass transport model has been established to explain such volume-diffusion-induced nanowire growth which cannot be explained by the conventional surface diffusion model alone. These findings significantly advance our understanding of nanowire growth processes and mass transport mechanisms and provide new guidelines for the design of nanowire-structured devices.

  16. Oxide thin films for spintronics application growth and characterization

    OpenAIRE

    Popovici, Nicoleta, 1973-

    2009-01-01

    Tese de doutoramento, Física (Física), Universidade de Lisboa, Faculdade de Ciências, 2009 During my PhD research I have synthesized thin films of a material known as a diluted magnetic semiconductor (DMS) using the pulsed laser deposition (PLD) technique. This material is envisioned to be of importance in the emerging field of spintronics where both the charge and the spin of the carriers can be combined to yield unique functionalities. It was envisaged that if spin polarized charge carri...

  17. Reaction Mechanisms of the Atomic Layer Deposition of Tin Oxide Thin Films Using Tributyltin Ethoxide and Ozone.

    Science.gov (United States)

    Nanayakkara, Charith E; Liu, Guo; Vega, Abraham; Dezelah, Charles L; Kanjolia, Ravindra K; Chabal, Yves J

    2017-06-20

    Uniform and conformal deposition of tin oxide thin films is important for several applications in electronics, gas sensing, and transparent conducting electrodes. Thermal atomic layer deposition (ALD) is often best suited for these applications, but its implementation requires a mechanistic understanding of the initial nucleation and subsequent ALD processes. To this end, in situ FTIR and ex situ XPS have been used to explore the ALD of tin oxide films using tributyltin ethoxide and ozone on an OH-terminated, SiO 2 -passivated Si(111) substrate. Direct chemisorption of tributyltin ethoxide on surface OH groups and clear evidence that subsequent ligand exchange are obtained, providing mechanistic insight. Upon ozone pulse, the butyl groups react with ozone, forming surface carbonate and formate. The subsequent tributyltin ethoxide pulse removes the carbonate and formate features with the appearance of the bands for CH stretching and bending modes of the precursor butyl ligands. This ligand-exchange behavior is repeated for subsequent cycles, as is characteristic of ALD processes, and is clearly observed for deposition temperatures of 200 and 300 °C. On the basis of the in situ vibrational data, a reaction mechanism for the ALD process of tributyltin ethoxide and ozone is presented, whereby ligands are fully eliminated. Complementary ex situ XPS depth profiles confirm that the bulk of the films is carbon-free, that is, formate and carbonate are not incorporated into the film during the deposition process, and that good-quality SnO x films are produced. Furthermore, the process was scaled up in a cross-flow reactor at 225 °C, which allowed the determination of the growth rate (0.62 Å/cycle) and confirmed a self-limiting ALD growth at 225 and 268 °C. An analysis of the temperature-dependence data reveals that growth rate increases linearly between 200 and 300 °C.

  18. Antimicrobial, Physicochemical, Mechanical, and Barrier Properties of Tapioca Starch Films Incorporated with Eucalyptus Extract

    Directory of Open Access Journals (Sweden)

    M. Rojhan

    2013-11-01

    Full Text Available Starch is found in abundance in nature and it is one of the raw materials used for food packagingbecause of the low price, biodegradability, good mechanical and barrier properties. The recycling ability ofcoating materials was significantly increased by using edible films and coating in comparison to traditionalpackaging and it could be an alternative for synthetic films. In this research, the effect of eucalyptus extract(Aqueous Extract was investigated on tapioca starch films. Tapioca starch films were prepared by castingmethod with addition of eucalyptus extract and a mixture of sorbitol/glycerol (weight ratio of 3 to 1 asplasticizers. Eucalyptus extract incorporated to the tapioca starch films were dried at different concentrations(0, 15, 25, and 35 of total solid under controlled conditions. Physicochemical properties such as waterabsorption capacity (WAC, water vapor permeability (WVP and mechanical properties of the films wereevaluated. Results showed that by increasing the concentration of eucalyptus extract, tensile strength wasincreased from 20.60 to 15.68 (MPa, also elongation was increased from 19.31 to 23.57 (% at break andYoung’s modulus was decreased from 800.31 to 500.32 (MPa. Also incorporation of eucalyptus extract in thestructure of biopolymer increased permeability of water vapor of starch films. Tapioca starch filmsincorporated with eucalyptus extract exhibited excellent antimicrobial activity against E. Coli. In summary,eucalyptus extract improves functional properties of tapioca starch films and this types of films can be used infood packaging.

  19. Catalytic effect of Al and AlN interlayer on the growth and properties of containing carbon films

    International Nuclear Information System (INIS)

    Zhou, Bing; Liu, Zhubo; Tang, Bin; Rogachev, A.V.

    2015-01-01

    Highlights: • DLC and CN x bilayers with Al (AlN) interlayer were fabricated by cathode arc technique. • Complete diffusion of Al and C atoms occurs at the interface of Al/DLC (CN x ) bilayer. • Al/CN x bilayer presents a higher content of Csp 3 /Csp 2 bonds. • The hardness of Al/DLC bilayer decreases but increases for the other bilayers. • Morphology of the bilayers was explained by growth mechanism of DLC and surface state of substrate. - Abstract: Diamond-like carbon (DLC) and carbon nitride (CN x ) bilayer films with Al and AlN interlayer were fabricated by pulse cathode arc technique. The structure, composition, morphology and mechanical properties of the films were investigated by Raman, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Knoop sclerometer and surface profilometer. The results indicated that the complete diffusion between C and Al atoms occurs in the Al/DLC and Al/CN x bilayer. Al interlayer induces the increase of the size and ordering of Csp 2 clusters in the films but AlN interlayer increases the disordering degree of Csp 2 clusters. XPS results showed that a higher content of Csp 3 /Csp 2 bonds presents in the Al/CN x bilayer, and Al and AlN interlayer decreases the atomic ratio of N/C. AFM with phase contrast mode illustrated the morphologic characteristics of the bilayer films. All the bilayers show a nano-structural surface. The morphology changes of the bilayer were well explained by the surface state of the substrate and the growth mechanism of DLC films. The hardness of Al/DLC bilayer decreases but it increases for the other bilayers compared to the corresponding DLC (CN x ) monolayer. The internal stress of the bilayer is significantly lower than that of the monolayer except for the AlN/CN x bilayer. These studies could make the difference at the time of choosing a suitable functional film for certain application

  20. Nano Indentation Inspection of the Mechanical Properties of Gold Nitride Thin Films

    Directory of Open Access Journals (Sweden)

    Armen Verdyan

    2007-10-01

    Full Text Available The morphology and the local mechanical properties of gold nitride thin films were studied by atomic force microscope (AFM. Gold nitride films were deposited for the first time on silicon substrate without any buffer layer at room temperature by reactive pulsed laser ablation deposition (RPLD. The films were fabricated on (100 Si wafers by RPLD technique in which KrF excimer laser was used to ablate a gold target in N2 atmosphere (0.1 GPa-100 Pa and ambient temperature. Scanning electron microscopy (SEM and atomic force microscopy inspections showed that the films were flat plane with rms roughness in the range of 35.1 nm-3.6 nm, depending on the deposition pressure. Rutherford backscattering spectrometry (RBS and energy dispersion spectroscopy (EDS used to detect the nitrogen concentration in the films, have revealed a composition close to Au3N. The film

  1. One-step growth of thin film SnS with large grains using MOCVD

    Science.gov (United States)

    Clayton, Andrew J.; Charbonneau, Cecile M. E.; Tsoi, Wing C.; Siderfin, Peter J.; Irvine, Stuart J. C.

    2018-01-01

    Abstract Thin film tin sulphide (SnS) films were produced with grain sizes greater than 1 μm using a one-step metal organic chemical vapour deposition process. Tin–doped indium oxide (ITO) was used as the substrate, having a similar work function to molybdenum typically used as the back contact, but with potential use of its transparency for bifacial illumination. Tetraethyltin and ditertiarybutylsulphide were used as precursors with process temperatures 430–470 °C to promote film growth with large grains. The film stoichiometry was controlled by varying the precursor partial pressure ratios and characterised with energy dispersive X-ray spectroscopy to optimise the SnS composition. X-ray diffraction and Raman spectroscopy were used to determine the phases that were present in the film and revealed that small amounts of ottemannite Sn2S3 was present when SnS was deposited on to the ITO using optimised growth parameters. Interaction at the SnS/ITO interface to form Sn2S3 was deduced to have resulted for all growth conditions. PMID:29511393

  2. Epitaxial thin film growth of LiH using a liquid-Li atomic template

    Energy Technology Data Exchange (ETDEWEB)

    Oguchi, Hiroyuki, E-mail: oguchi@nanosys.mech.tohoku.ac.jp [Department of Nanomechanics, Tohoku University, Sendai 980-8579 (Japan); Micro System Integration Center (muSIC), Tohoku University, Sendai 980-0845 (Japan); Ikeshoji, Tamio; Orimo, Shin-ichi [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577 (Japan); Ohsawa, Takeo; Shiraki, Susumu; Hitosugi, Taro [Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577 (Japan); Kuwano, Hiroki [Department of Nanomechanics, Tohoku University, Sendai 980-8579 (Japan)

    2014-11-24

    We report on the synthesis of lithium hydride (LiH) epitaxial thin films through the hydrogenation of a Li melt, forming abrupt LiH/MgO interface. Experimental and first-principles molecular dynamics studies reveal a comprehensive microscopic picture of the crystallization processes, which sheds light on the fundamental atomistic growth processes that have remained unknown in the vapor-liquid-solid method. We found that the periodic structure that formed, because of the liquid-Li atoms at the film/MgO-substrate interface, serves as an atomic template for the epitaxial growth of LiH crystals. In contrast, films grown on the Al{sub 2}O{sub 3} substrates indicated polycrystalline films with a LiAlO{sub 2} secondary phase. These results and the proposed growth process provide insights into the preparation of other alkaline metal hydride thin films on oxides. Further, our investigations open the way to explore fundamental physics and chemistry of metal hydrides including possible phenomena that emerge at the heterointerfaces of metal hydrides.

  3. Why in situ, real-time characterization of thin film growth processes?

    International Nuclear Information System (INIS)

    Auciello, O.; Krauss, A.R.

    1995-01-01

    Since thin-film growth occurs at the surface, the analytical methods should be highly surface-specific. although subsurface diffusion and chemical processes also affect film properties. Sampling depth and ambient-gas is compatibility are key factors which must be considered when choosing in situ probes of thin-film growth phenomena. In most cases, the sampling depth depends on the mean range of the exit species (ion, photon, or electron) in the sample. The techniques that are discussed in this issue of the MRS Bulletin (1) have been chosen because they may be used for in situ, real-time analysis of film-growth phenomena in vacuum and in the presence of ambient gases resulting either from the deposition process or as a requirement for the production of the desired chemical phase. A second criterion for inclusion is that the instrumentation be sufficiently compact and inexpensive to permit use as a dedicated tool in a thin-film deposition system

  4. Epitaxial thin film growth of LiH using a liquid-Li atomic template

    International Nuclear Information System (INIS)

    Oguchi, Hiroyuki; Ikeshoji, Tamio; Orimo, Shin-ichi; Ohsawa, Takeo; Shiraki, Susumu; Hitosugi, Taro; Kuwano, Hiroki

    2014-01-01

    We report on the synthesis of lithium hydride (LiH) epitaxial thin films through the hydrogenation of a Li melt, forming abrupt LiH/MgO interface. Experimental and first-principles molecular dynamics studies reveal a comprehensive microscopic picture of the crystallization processes, which sheds light on the fundamental atomistic growth processes that have remained unknown in the vapor-liquid-solid method. We found that the periodic structure that formed, because of the liquid-Li atoms at the film/MgO-substrate interface, serves as an atomic template for the epitaxial growth of LiH crystals. In contrast, films grown on the Al 2 O 3 substrates indicated polycrystalline films with a LiAlO 2 secondary phase. These results and the proposed growth process provide insights into the preparation of other alkaline metal hydride thin films on oxides. Further, our investigations open the way to explore fundamental physics and chemistry of metal hydrides including possible phenomena that emerge at the heterointerfaces of metal hydrides

  5. Explicit relationship between electrical and topological degradation of polymer-supported metal films subjected to mechanical loading

    Science.gov (United States)

    Glushko, O.; Kraker, P.; Cordill, M. J.

    2017-05-01

    For a comprehensive characterization of mechanical reliability of metallization layers on polymer substrates, both electrical and mechanical degradation should be taken into account. Although it is evident that cracking of a conductive film should lead to electrical degradation, the quantitative relationship between the growth of electric resistance and parameters of the induced crack pattern has remained thus far unexplored. With the help of finite element modelling, we were able to find an explicit and concise expression which shows that electrical resistance grows with the fourth order of the crack length and second order of the areal crack density. The discovered relationship was verified by comparison with the experimental results of tensile testing of polymer-supported thin metal films. The presented model is independent of the length scale and can be applied to films with different thicknesses as long as Ohm's law is valid. It is demonstrated that the linear crack density is an ambiguous parameter, which does not properly capture the development of a crack pattern. For the unambiguous characterization of the intensity of a crack pattern, a universal dimensionless factor is proposed. The presented results show that there is a wide range of possible crack patterns which do not lead to electrical failure of a conductive film that can be used for the failure-free design of flexible electronic devices.

  6. CCD camera-based analysis of thin film growth in industrial PACVD processes

    Science.gov (United States)

    Zauner, G.; Schulte, T.; Forsich, C.; Heim, Daniel

    2013-04-01

    In this paper we present a method for the characterization of (semi-transparent) thin film growth during PACVD processes (plasma assisted chemical vapour deposition), based on analysis of thermal radiation by means of nearinfrared imaging. Due to interference effects during thin film growth, characteristic emissivity signal variations can be observed which allow very detailed spatio-temporal analysis of growth characteristics (e.g. relative growth rates). We use a standard CCD camera with a near-infrared band-pass filter (center wavelength 1030 nm, FWHM 10nm) as a thermal imaging device. The spectral sensitivity of a Si-CCD sensor at 1μm is sufficient to allow the imaging of thermal radiation at temperatures above approx. 400°C, whereas light emissions from plasma discharges (which mainly occur in the visible range of the electromagnetic spectrum) barely affect the image formation.

  7. Research Update: Stoichiometry controlled oxide thin film growth by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Groenen, Rik; Smit, Jasper; Orsel, Kasper; Vailionis, Arturas; Bastiaens, Bert; Huijben, Mark; Boller, Klaus; Rijnders, Guus; Koster, Gertjan, E-mail: g.koster@utwente.nl [Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede (Netherlands)

    2015-07-01

    The oxidation of species in the plasma plume during pulsed laser deposition controls both the stoichiometry as well as the growth kinetics of the deposited SrTiO{sub 3} thin films, instead of the commonly assumed mass distribution in the plasma plume and the kinetic energy of the arriving species. It was observed by X-ray diffraction that SrTiO{sub 3} stoichiometry depends on the composition of the background gas during deposition, where in a relative small pressure range between 10{sup −2} mbars and 10{sup −1} mbars oxygen partial pressure, the resulting film becomes fully stoichiometric. Furthermore, upon increasing the oxygen (partial) pressure, the growth mode changes from 3D island growth to a 2D layer-by-layer growth mode as observed by reflection high energy electron diffraction.

  8. Growth rate and properties of cadmium telluride heteroepitaxy films during plasmochemical deposition from organometallic compounds

    International Nuclear Information System (INIS)

    Benyushis, T.I.; Vasilevskij, M.I.; Gurylev, B.V.; Ershov, S.N.; Ozerov, A.B.; Parker, T.D.

    1989-01-01

    The results of studying the peculiarities of growth and properties of CdTe films grown by precipitation from organometallic compound (OMC) vapors in the inductive high-frequency (HF) discharge, are given. The effect on the growth process of such parameters as substrate temperature, discarge characteristics, the correlation of partial component pressures, is studied. The epitaxial growth is observed starting from a certain threshold value of HF-power connected to the inductor up to T ≅ 150 deg C. The films of stoichiometric composition are prepared with the correlation of partial pressures of tellurium and cadmium OMC equalling 1.5. The temperature dependence of growth rate is anomalous for the gas phase epitaxy and is comparable with that usually observed during molecular-beam epitaxy

  9. Transport, mechanical and global migration data of multilayer copolyamide nanocomposite films with different layouts.

    Science.gov (United States)

    Scarfato, P; Garofalo, E; Di Maio, L; Incarnato, L

    2017-06-01

    Transport, mechanical and global migration data concern multilayer food packaging films with different layouts, all incorporating a layered silicate/polyamide nanocomposite as oxygen barrier layer, and a low-density polyethylene (LDPE) as moisture resistant layer in direct contact with food. The data are related to "Tuning of co-extrusion processing conditions and film layout to optimize the performances of PA/PE multilayer nanocomposite films for food packaging" by Garofalo et al. (2017) [1]. Nanocomposite multilayer films, with different relative layer thicknesses and clay types, were produced using a laboratory scale co-extrusion blown-film equipment and were analyzed in terms of transport to oxygen and water vapor, mechanical properties and overall migration. The results have shown that all the multilayer hybrid films, based on the copolyamide layer filled with Cloisite 30B, displayed the most significant oxygen barrier improvements and the best mechanical properties compared to the unfilled films. No significant alteration of the overall migration values was observed, as expectable [2], [3], [4]. The performance improvement was more relevant in the case of the film with the thinner nanocomposite layer.

  10. Transport, mechanical and global migration data of multilayer copolyamide nanocomposite films with different layouts

    Directory of Open Access Journals (Sweden)

    P. Scarfato

    2017-06-01

    Full Text Available Transport, mechanical and global migration data concern multilayer food packaging films with different layouts, all incorporating a layered silicate/polyamide nanocomposite as oxygen barrier layer, and a low-density polyethylene (LDPE as moisture resistant layer in direct contact with food. The data are related to “Tuning of co-extrusion processing conditions and film layout to optimize the performances of PA/PE multilayer nanocomposite films for food packaging” by Garofalo et al. (2017 [1]. Nanocomposite multilayer films, with different relative layer thicknesses and clay types, were produced using a laboratory scale co-extrusion blown-film equipment and were analyzed in terms of transport to oxygen and water vapor, mechanical properties and overall migration. The results have shown that all the multilayer hybrid films, based on the copolyamide layer filled with Cloisite 30B, displayed the most significant oxygen barrier improvements and the best mechanical properties compared to the unfilled films. No significant alteration of the overall migration values was observed, as expectable [2–4]. The performance improvement was more relevant in the case of the film with the thinner nanocomposite layer.

  11. Substrate mediated growth of organic semiconducting thin films; Templateffekte bei der Strukturierung organischer Halbleiterfilme

    Energy Technology Data Exchange (ETDEWEB)

    Goetzen, Jan

    2010-09-17

    Since electronic properties of molecular materials are closely related to their structural order a precise control of the molecular packing and crystalline orientation of thin films is of vital interest for an optimization of organic electronic devices. Of particular interest in this respect is the initial stage of film formation which is largely governed by the interplay of intermolecular and molecule-substrate interactions. One approach to control the molecular film structure is based on substrate mediated growth. In this respect we have studied structural properties of thin films of pentacene, pentacene- 5,7,12,14-tetrone and perfluoro-pentacene which were grown onto various substrates including metals, metal oxides and graphite. On metal surfaces the molecules initially form a chemisorbed monolayer where molecules even can be uniformly aligned when using appropriate substrates with twofold symmetry. Further deposition, however, is accompanied by a pronounced dewetting and formation of disjoined islands which results from a large structural mismatch between the molecular arrangement in the monolayer and the crystalline phase. In some cases it is possible to orient such islands by utilizing step mediated nucleation and decoration of step bunches which allows the preparation of azimuthally well oriented elongated islands. On single crystalline oxides the growth parallels the situation found before for SiO{sub 2} where islands of upright oriented molecules are formed. The growth on graphite is somewhat particular since the lattice provides a natural template for acenes yielding epitaxially ordered monolayer films with planar adsorption geometry like in case of metals. Interestingly, however, no dewetting occurs upon further growth and instead rather smooth films are formed. The detailed analysis for the case of pentacene showed that the substrate-molecule interaction actually is weaker than the intermolecular interaction so that multilayer films can lift the

  12. Growth properties of poly(tetrafluoroethylene) films by synchrotron radiation ablation

    International Nuclear Information System (INIS)

    Guo, Qixin; Kugino, Takashi; Kume, Yusuke; Mitsuishi, Yoshiaki; Tanaka, Tooru; Nishi, Mitsuhiro; Ogawa, Hiroshi

    2007-01-01

    High-quality poly(tetrafluoroethylene) (PTFE) films have been grown on Si substrates by synchrotron radiation ablation of a PTFE target. Only doublet absorption structures assigned to C-F asymmetric and symmetric stretching vibrations in CF 2 groups are observed, suggesting that the CF 2 groups in the grown PTFE film are organized in an ordered manner through linear attachment. The growth rate of the PTFE films increases with increasing target temperature, while it decreases with increasing substrate temperature. It has been shown that the thickness of the PTFE film with a high-spatial-resolution structure can be easily controlled at nanometer order by changing the synchrotron radiation irradiation dose. (author)

  13. Coloration and bleaching mechanism of niobium oxide electrochromic thin films; Sanka niobu electromic usumaku no chakushoshoku mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimura, K.; Miki, T.; Tazawa, M.; Jin, P.; Igarashi, K.; Tanemura, S. [National Industrial Research Institute of Nagoya, Nagoya (Japan)

    1997-11-25

    In order to search for the coloration and bleaching mechanism of niobium oxide, considerations were given on optical properties and electron conditions in niobium oxide thin films (glass plates as substrates coated with ITO) prepared by using the reactive DC magnetron sputtering process. The films were so grown that their thickness will all be 100 nm to facilitate data comparison. Coloration and bleaching of the grown test films were conducted by cyclic voltammetry. Electron spectra were measured by using XPS, and electron energy was analyzed. Coloration of niobium oxide occurs as a result of change in valency electron state from an Nb {sup 5+} state to an Nb {sup 4+} state, while change in the XPS spectra also corresponds with the above change. However, the XPS spectra differ greatly between crystalline samples and amorphous samples. The coloration and bleaching mechanism of the crystallized Nb2O5 film can be explained by a reaction formula similar to that for WO3. However, with regard to the amorphous Nb2O5 film, an independent reaction involving water in the film seems to occur together with the same reaction as in the crystallized film. 9 refs., 5 figs.

  14. Growth and characterization of ZnO thin films prepared by electrodeposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Fahoume, M.; Maghfoul, O.; Aggour, M. [L.P.M.C., Faculte des Sciences, Universite Ibn Tofail, BP. 133-14000 Kenitra (Morocco); Hartiti, B. [L.P.M.A.E.R., Faculte des Sciences et Techniques, B.P. 146 Mohammedia (Morocco); Chraibi, F.; Ennaoui, A. [L.P.M., Faculte des Sciences, Universite Mohammed V, BP.1014 Rabat (Morocco)

    2006-06-15

    ZnO thin films were deposited on either indium tin oxide-coated glass or copper substrate by the electrodeposition process, using zinc chloride and flowing air as precursors. The effect of pH on the structural and morphological ZnO films was studied and the optimum deposition conditions have been outlined. The kinetics of the growth of the films have been investigated. We note that the rate of deposition of ZnO in an acidic solution was larger than in a basic solution. The structure of the films was studied using X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The surface morphology and thickness of the films were determined using scanning electron microscopy. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure (zincite) at pH 4. The optical transmittance of ZnO decreases with varying film thickness. The optical energy bandgap was found to be 3.26eV. (author)

  15. Growth of layered superconductor β-PdBi{sub 2} films using molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, N.V., E-mail: denisov@iacp.dvo.ru [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); Matetskiy, A.V.; Tupkalo, A.V. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); Zotov, A.V. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation); Department of Electronics, Vladivostok State University of Economics and Service, 690600 Vladivostok (Russian Federation); Saranin, A.A. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation)

    2017-04-15

    Highlights: • Bulk β-PdBi{sub 2} is layered material with advanced properties of topological superconductor. • We present a method for growing β-PdBi{sub 2} films of a desired thickness. • Method utilizes MBE growth of β-PdBi{sub 2}, using Bi(111) film on Si(111) as a template. • Electronic and superconducting properties of the films are similar to those of bulk β-PdBi{sub 2}. - Abstract: Bulk β-PdBi{sub 2} layered material exhibits advanced properties and is supposed to be probable topological superconductor. We present a method based on molecular beam epitaxy that allows us to grow β-PdBi{sub 2} films from a single β-PdBi{sub 2} triple layer up to the dozens of triple layers, using Bi(111) film on Si(111) as a template. The grown films demonstrate structural, electronic and superconducting properties similar to those of bulk β-PdBi{sub 2} crystals. Ability to grow the β-PdBi{sub 2} films of desired thickness opens the promising possibilities to explore fascinating properties of this advanced material.

  16. Controlled Growth of Conductive AlN Thin Films by Plasma-Assisted Reactive Evaporation

    Science.gov (United States)

    Alizadeh, M.; Goh, B. T.; Rahman, S. A.

    2017-07-01

    In this work, the growth of conductive AlN thin films by plasma-assisted reactive evaporation at different filament-to-substrate distances was presented and discussed. The elemental composition, surface morphology, structural, optical, and electrical properties of the films were examined by energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectroscopy (FTIR), optical measurement, and current-voltage ( I- V) characterizations. The electrical study revealed that the films are conductive, as ohmic conductivity was observed from I- V results. The GIXRD results of AlN thin films showed that by decreasing the distance, the intensity of the peak corresponding to metallic Al decreases while that of AlN increases. EDX and XPS results indicated that at shorter distances, the incorporation of N into the AlN films is enhanced. This was further confirmed by FTIR results, which showed that the incorporation of Al-N bonds in the grown AlN films was enhanced by decreasing the distance. It was shown that the optical absorption edge of the grown films shifts from the near-ultraviolet (UV) region to far-UV as the distance is decreased.

  17. Development, physiochemical characterization and forming mechanism of Flammulina velutipes polysaccharide-based edible films.

    Science.gov (United States)

    Du, Hengjun; Hu, Qiuhui; Yang, Wenjian; Pei, Fei; Kimatu, Benard Muinde; Ma, Ning; Fang, Yong; Cao, Chongjiang; Zhao, Liyan

    2016-11-05

    Edible films of Flammulina velutipes polysaccharide were prepared and characterized in terms of rheological, optical, morphologic, mechanical and barrier properties to evaluate their potential application in food packaging. Results suggested that FVP film prepared by the solution of 1:150 (w/v) had the optimal mechanical property, smooth and uniform surface, and good barrier property to water (37.92±2.00gmm/m(2)hkPa) and oxygen (37.92±2.01meq/kg). The capacity of film-formation might be related to inter-molecular and intra-molecular hydrogen bonds of FVP and formation of β-glycosidic bonds during the process of film-formation. These findings will contribute to a theoretical basis for the development of FVP film in food packaging. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-06-21

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

  19. Mechanistic Insights into Growth of Surface‐Mounted Metal‐Organic Framework Films Resolved by Infrared (Nano‐) Spectroscopy

    OpenAIRE

    Delen, Guusje; Ristanović, Zoran; Mandemaker, Laurens D. B.; Weckhuysen, Bert M.

    2017-01-01

    Abstract Control over assembly, orientation, and defect‐free growth of metal‐organic framework (MOF) films is crucial for their future applications. A layer‐by‐layer approach is considered a suitable method to synthesize highly oriented films of numerous MOF topologies, but the initial stages of the film growth remain poorly understood. Here we use a combination of infrared (IR) reflection absorption spectroscopy and atomic force microscopy (AFM)‐IR imaging to investigate the assembly and gro...

  20. Nitrogen Dioxide Sensing Properties and Mechanism of Copper Phthalocyanine Film

    International Nuclear Information System (INIS)

    Cheng-Jun, Qiu; Quan-Liang, Zhao; Mao-Sheng, Cao; Yan-Wei, Dou; Wei, Qij; Yan-Mei, Sun; Jie, Yuan

    2008-01-01

    Copper phthalocyanine film, a p-type organic semiconductor, is synthesized by vacuum sublimation and its surface morphology is characterized by SEM. A silicon-based copper phthalocyanine film gas sensor for NO 2 detection is fabricated by MEMS technology. The results show that the resistance and sensitivity of copper phthalocyanine film decrease obviously as the NO 2 concentration increases from 0 ppm to 100ppm. However, the sensitivity nearly keeps a constant of 0.158 between 30 ppm and 70 ppm. The best working temperature of the gas sensor is 90deg G for NO 2 gas concentrations of 10 ppm, 20 ppm and 30 ppm, which is much lower than that of general metal oxide gas sensor

  1. Effects of pH and Salts on Physical and Mechanical Properties of Pea Starch Films.

    Science.gov (United States)

    Choi, W S; Patel, D; Han, J H

    2016-07-01

    To identify the significant contribution of intermolecular hydrogen bonds of starch molecules to the film structure formation, pH of film-forming solutions was adjusted and also various salts (NaCl, CaCl2 , CaSO4 , and K2 SO4 ) were mixed into the glycerol-plasticized pea starch film. The film made from pH 7 possessed the highest tensile strength-at-break (2 times) and elastic modulus (4 to 15 times) and the lowest elongation-at-break compared with those of the films made from acid and alkali environments. The pH 7 film also has the highest film density and the lowest total soluble matter. At the level of 0.01 to 0.1 M of CaSO4 and 0.1 M of K2 SO4 in a kilogram of starch, the water solubility of the film increased, while chloride salts slightly lowered the solubility. NaCl and CaSO4 reduced water vapor permeability (WVP), while CaCl2 slightly increased WVP at 0.01 and 0.06 M concentrations, and K2 SO4 significantly increased WVP at 0.03 and 0.15 M. Presence of salts increased tensile strength (5 to 14 times than the control films) and elastic modulus (35 to 180 times) of starch film at 0.01 to 0.03 M of CaSO4 and K2 SO4 . Elongation-at-break increased significantly as salt concentration increases to an optimal level. However, when the concentration exceeded above the optimal level, the E of starch films decreased and showed no significant difference from the control film. Overall, the addition of salts modified physical and mechanical properties of pea starch films more than pH adjustment without any salt addition. © 2016 Institute of Food Technologists®

  2. Reduction of resistivity in Cu thin films by partial oxidation: Microstructural mechanisms

    International Nuclear Information System (INIS)

    Prater, Walter L.; Allen, Emily L.; Lee, Wen-Y.; Toney, Michael F.; Daniels, Jonathan; Hedstrom, Jonathan A.

    2004-01-01

    We report on the electrical resistance and microstructure of sputter deposited copper thin films grown in an oxygen containing ion-beam sputtering atmosphere. For films thinner than 5 nm, 6%-10% oxygen causes a minimum in film resistivity, while for thicker films, there is a monotonic increase in resistivity. X-ray reflectivity measurements show significantly smoother films for these oxygen flow rates. X-ray diffraction shows that the oxygen doping causes a refinement of the copper grain size and the formation of cuprous oxide. We suggest that the formation of cuprous oxide limits copper grain growth, which causes smoother interfaces, and thus reduces resistivity by increasing specular scattering of electrons at interfaces

  3. Beyond buckling: humidity-independent measurement of the mechanical properties of green nanobiocomposite films.

    Science.gov (United States)

    Gill, Urooj; Sutherland, Travis; Himbert, Sebastian; Zhu, Yujie; Rheinstädter, Maikel C; Cranston, Emily D; Moran-Mirabal, Jose M

    2017-06-14

    Precise knowledge of the mechanical properties of emerging nanomaterials and nanocomposites is crucial to match their performance with suitable applications. While methods to characterize mechanical properties exist, they are limited by instrument sensitivity and sample requirements. For bio-based nanomaterials this challenge is exacerbated by the extreme dependence of mechanical properties on humidity. This work presents an alternative approach, based on polymer shrinking-induced wrinkling mechanics, to determine the elastic modulus of nanobiocomposite films in a humidity-independent manner. Layer-by-layer (LbL) films containing cellulose nanocrystals (CNCs) and water-soluble polymers were deposited onto pre-stressed polystyrene substrates followed by thermal shrinking, which wrinkled the films to give them characteristic topographies. Three deposition parameters were varied during LbL assembly: (1) polymer type (xyloglucan - XG, or polyethyleneimine - PEI); (2) polymer concentration (0.1 or 1 wt%); and (3) number of deposition cycles, resulting in 10-600 nm thick nanobiocomposite films with tuneable compositions. Fast Fourier transform analysis on electron microscopy images of the wrinkled films was used to calculate humidity-independent moduli of 70 ± 2 GPa for CNC-XG 0.1 , 72 ± 2 GPa for CNC-PEI 0.1 , and 32.2 ± 0.8 GPa for CNC-PEI 1.0 films. This structuring method is straightforward and amenable to a wide range of supported thin films.

  4. Growth and morphology of sputtered aluminum thin films on P3HT surfaces.

    Science.gov (United States)

    Kaune, Gunar; Metwalli, Ezzeldin; Meier, Robert; Körstgens, Volker; Schlage, Kai; Couet, Sebastien; Röhlsberger, Ralf; Roth, Stephan V; Müller-Buschbaum, Peter

    2011-04-01

    Growth and morphology of an aluminum (Al) contact on a poly(3-hexylthiophene) (P3HT) thin film are investigated with X-ray methods and related to the interactions at the Al:P3HT interface. Grazing incidence small-angle scattering (GISAXS) is applied in situ during Al sputter deposition to monitor the growth of the layer. A growth mode is found, in which the polymer surface is wetted and rapidly covered with a continuous layer. This growth type results in a homogeneous film without voids and is explained by the strong chemical interaction between Al and P3HT, which suppresses the formation of three-dimensional cluster structures. A corresponding three stage growth model (surface bonding, agglomeration, and layer growth) is derived. X-ray reflectivity shows the penetration of Al atoms into the P3HT film during deposition and the presence of a 2 nm thick intermixing layer at the Al:P3HT interface. © 2011 American Chemical Society

  5. High growth rate of a-SiC: H films using ethane carbon source by ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 36; Issue 7. High growth rate of a-SiC:H films using ethane carbon source by HW-CVD method. Mahesh M Kamble Vaishali S Waman Sanjay S Ghosh Azam Mayabadi Vasant G Sathe T Shripathi Habib M Pathan Sandesh R Jadkar. Volume 36 Issue 7 December 2013 ...

  6. Smooth Growth of Organic Semiconductor Films on Graphene for High-Efficiency Electronics

    NARCIS (Netherlands)

    Hlawacek, G.; Khokhar, F.S.; van Gastel, Raoul; Poelsema, Bene; Teichert, Christian

    2011-01-01

    High-quality thin films of conjugated molecules with smooth interfaces are important to assist the advent of organic electronics. Here, we report on the layer-by-layer growth of the organic semiconductor molecule p-sexiphenyl (6P) on the transparent electrode material graphene. Low energy electron

  7. The generation and detection of high flux atomic oxygen for physical vapor deposition thin film growth

    NARCIS (Netherlands)

    Ingle, N.J.C.; Hammond, R.H.; Beasley, M.R.; Blank, David H.A.

    1999-01-01

    The growth of many epitaxial thin-film oxides is significantly enhanced with the use of an oxidizing agent such as atomic oxygen, ozone, or NO2. We developed a flow-through microwave plasma source to generate large atomic oxygen fluxes while maintaining vacuum pressures of less that 1×10¿4 Torr.

  8. Growth and characterization of Hg 1– Cd Te epitaxial films by ...

    Indian Academy of Sciences (India)

    Growth of Hg1–CdTe epitaxial films by a new technique called asymmetric vapour phase epitaxy (ASVPE) has been carried out on CdTe and CZT substrates. The critical problems faced in normal vapour phase epitaxy technique like poor surface morphology, composition gradient and dislocation multiplication have ...

  9. Growth of n-alkane films on a single-crystal substrate

    DEFF Research Database (Denmark)

    Wu, Z. U.; Ehrlich, S. N.; Matthies, B.

    2001-01-01

    The structure and growth mode of alkane films (n-C/sub n/H/sub 2n+2/; n=4, 6, 7) adsorbed on a Ag(111) surface have been investigated by synchrotron X-ray scattering. New models are proposed for the butane (n=4) and hexane (n=6) monolayer and butane bilayer structures. Specular reflectivity scans...

  10. On the preparation and growth of a-Si:H thin films by Hg-sensitised ...

    African Journals Online (AJOL)

    It also recall and summarizes some fundamental issues such experimental systems or apparatus particularities, the analysis of gas-phase reactions in the reactor, the surface reaction model of SiH3 and H during the film growth and all the kinetic model for lamp induced Photo-CVD. Key words: Hydrogenated Amorphous ...

  11. Thermo-Mechanical Fatigue Crack Growth of RR1000

    Directory of Open Access Journals (Sweden)

    Christopher John Pretty

    2017-01-01

    Full Text Available Non-isothermal conditions during flight cycles have long led to the requirement for thermo-mechanical fatigue (TMF evaluation of aerospace materials. However, the increased temperatures within the gas turbine engine have meant that the requirements for TMF testing now extend to disc alloys along with blade materials. As such, fatigue crack growth rates are required to be evaluated under non-isothermal conditions along with the development of a detailed understanding of related failure mechanisms. In the current work, a TMF crack growth testing method has been developed utilising induction heating and direct current potential drop techniques for polycrystalline nickel-based superalloys, such as RR1000. Results have shown that in-phase (IP testing produces accelerated crack growth rates compared with out-of-phase (OOP due to increased temperature at peak stress and therefore increased time dependent crack growth. The ordering of the crack growth rates is supported by detailed fractographic analysis which shows intergranular crack growth in IP test specimens, and transgranular crack growth in 90° OOP and 180° OOP tests. Isothermal tests have also been carried out for comparison of crack growth rates at the point of peak stress in the TMF cycles.

  12. Growth mode, morphology, and reducibility of CeO{sub 2}(111) thin films on Cu(111)

    Energy Technology Data Exchange (ETDEWEB)

    Dvorak, Filip; Stetsovych, Oleksandr; Matolinova, Iva; Tsud, Natalya; Skoda, Michal; Myslivecek, Josef; Matolin, Vladimir [Charles University, Faculty of Mathematics and Physics, V Holesovickach 2, Praha 8 (Czech Republic); Steger, Michael; Cherradi, El Miloudi [Heinrich-Heine-Universitaet, Institut fuer Experimentelle Physik der Kondensierten Materie, Universitaetsstrasse 1, Duesseldorf (Germany); Skala, Tomas [Sincrotrone Trieste SCpA, Strada Statale 14, km 163.5, Basovizza-Trieste (Italy)

    2011-07-01

    We investigate morphology and degree of reduction in model oxide system CeO{sub 2} (ceria) on Cu(111) using scanning tunneling microscopy and photoelectron spectroscopy. We identify growth mechanisms of ceria on Cu(111) - formation of incomplete oxide interfacial layer and formation of three-dimensional ceria pyramids by stacking of monolayer-high islands. Using these mechanisms we control the coverage, the number of open monolayers, and the step density of ceria thin films on Cu(111). Annealing in vacuum allows us to control besides the morphology also the degree of ceria surface reduction. We find a correlation between surface reduction and morphological stability in annealed ceria layers. Oriented and stoichiometric thin films of ceria on Cu(111) can be prepared at temperatures as low as 150 C and 250 C. Both the morphology and the degree of reduction of these films readily change with increasing temperature, which must be accounted for in evaluating temperature-programmed experiments with ceria on Cu(111).

  13. Corrosion resistance and biocompatibility of zirconium oxynitride thin film growth by RF sputtering

    International Nuclear Information System (INIS)

    Cubillos, G. I.; Olaya, J. J.; Clavijo, D.; Alfonso, J. E.; Bethencourt, M.

    2012-01-01

    Thin films of zirconium oxynitride were grown on common glass, silicon (100) and stainless steel 316 L substrates using the reactive RF magnetron sputtering technique. The films were analyzed through structural, morphological and biocompatibility studies. The structural analysis was carried out using X-ray diffraction (XRD), and the morphological analysis was carried out using scanning electron microscopy (Sem) and atomic force microscopy (AFM). These studies were done as a function of growth parameters, such as power applied to the target, substrate temperature, and flow ratios. The corrosion resistance studies were made on samples of stainless steel 316 L coated and uncoated with Zr x N y O films, through of polarization curves. The studies of biocompatibility were carried out on zirconium oxynitride films deposited on stainless steel 316 L through proliferation and cellular adhesion. The XRD analysis shows that films deposited at 623 K, with a flow ratio ΦN 2 /ΦO 2 of 1.25 and a total deposit time of 30 minutes grew preferentially oriented along the (111) plane of the zirconium oxynitride monoclinic phase. The Sem analyses showed that the films grew homogeneously, and the AFM studies indicated that the average rugosity of the film was 5.9 nm and the average particle size was 150 nm. The analysis of the corrosion resistant, shows that the stainless steel coated with the film was increased a factor 10. Finally; through the analysis of the biocompatibility we established that the films have a better surface than the substrate (stainless steel 316 L) in terms of the adhesion and proliferation of bone cells. (Author)

  14. Analysis of post-exposure density growth in radiochromic film with respect to the radiation dose.

    Science.gov (United States)

    Shima, Katsumi; Tateoka, Kunihiko; Saitoh, Yuichi; Suzuki, Junji; Yaegashi, Yuji; Fujimoto, Kazunori; Nakazawa, Takuya; Nakata, Akihiro; Abe, Tadanori; Imai, Sho; Sakata, Kouichi; Hareyama, Masato

    2012-01-01

    The post-exposure density growth (PEDG) is one of the characteristics of radiochromic film (RCF). In film dosimetry using RCF and a flatbed scanner, pixel values read out from the RCF are converted to dose (hereafter, film dose) by using a calibration curve. The aim of this study is to analyze the relationship between the pixel value read out from the RCF and the PEDG, and that between the film dose converted from the RCF and the PEDG. The film (GAFCHROMIC EBT) was irradiated with 10-MV X-rays in an ascending 11-dose-step arrangement. The pixel values of the irradiated EBT film were measured at arbitrary hours using an Epson flatbed scanner. In this study, the reference time was 24 h after irradiation, and all dose conversions from the pixel values read out from the EBT film were made using a calibration curve for 24 h after irradiation. For delivered doses of 33 and 348 cGy, the measured pixel values at 0.1 and 16 h after irradiation represented ranges of -9.6% to -0.7% and -3.9% to -0.3%, respectively, of the reference value. The relative changes between the pixel values read out from the EBT film at each elapsed time and that at the reference time decreased with increasing delivered dose. However, the difference range for all the film doses had a width of approximately -10% of the reference value at elapsed times from 0.1 to 16 h, and it showed no dependence on the delivered dose.

  15. Corrosion resistance and biocompatibility of zirconium oxynitride thin film growth by RF sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Cubillos, G. I.; Olaya, J. J.; Clavijo, D.; Alfonso, J. E. [Universidad Nacional de Colombia, Carrera 45 No. 26-85, AA 14490 Bogota D. C. (Colombia); Bethencourt, M., E-mail: jealfonsoo@unal.edu.co [Universidad de Cadiz, Centro Andaluz de Ciencia y Tecnologia Marinas, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Av. Republica de Saharaui, Puerto Real, E-11510 Cadiz (Spain)

    2012-07-01

    Thin films of zirconium oxynitride were grown on common glass, silicon (100) and stainless steel 316 L substrates using the reactive RF magnetron sputtering technique. The films were analyzed through structural, morphological and biocompatibility studies. The structural analysis was carried out using X-ray diffraction (XRD), and the morphological analysis was carried out using scanning electron microscopy (Sem) and atomic force microscopy (AFM). These studies were done as a function of growth parameters, such as power applied to the target, substrate temperature, and flow ratios. The corrosion resistance studies were made on samples of stainless steel 316 L coated and uncoated with Zr{sub x}N{sub y}O films, through of polarization curves. The studies of biocompatibility were carried out on zirconium oxynitride films deposited on stainless steel 316 L through proliferation and cellular adhesion. The XRD analysis shows that films deposited at 623 K, with a flow ratio {Phi}N{sub 2}/{Phi}O{sub 2} of 1.25 and a total deposit time of 30 minutes grew preferentially oriented along the (111) plane of the zirconium oxynitride monoclinic phase. The Sem analyses showed that the films grew homogeneously, and the AFM studies indicated that the average rugosity of the film was 5.9 nm and the average particle size was 150 nm. The analysis of the corrosion resistant, shows that the stainless steel coated with the film was increased a factor 10. Finally; through the analysis of the biocompatibility we established that the films have a better surface than the substrate (stainless steel 316 L) in terms of the adhesion and proliferation of bone cells. (Author)

  16. On the mechanical effects of a nanocrystallisation treatment for ZrO2 oxide films growing on a zirconium alloy

    International Nuclear Information System (INIS)

    Panicaud, B.; Grosseau-Poussard, J.-L.; Retraint, D.; Guérain, M.; Li, L.

    2013-01-01

    Highlights: ► Raman spectroscopy is performed to determine the stress evolution in a Zr/ZrO 2 system. ► Analytical relations are used to determine material characteristics. ► A specific modelling of the mechanical fields within the oxide is done. ► Relaxation and growth parameters are identified from an inverse method. - Abstract: In the present work, mechanical features are investigated in the case of ZrO 2 thermal oxide films growing on a Zr alloy at the temperature of 550 °C. The effects of a nanocrystallisation treatment on high temperature oxidation of a zirconium alloy are specifically studied. High temperature oxidation is performed in order to show benefits of such a nanocrystallisation on corrosion resistance and its influence on the mechanical fields. Experimental results obtained by Raman spectroscopy give the growth stress evolution in ZrO 2 films. Using a modelling of the system, both asymptotic forms and an optimization procedure are developed to determine the mechanical characteristic parameters of the system.

  17. Optical and mechanical properties of diamond like carbon films ...

    Indian Academy of Sciences (India)

    Diamond like carbon (DLC) films were deposited on Si (111) substrates by microwave electron cyclotron resonance (ECR) plasma chemical vapour deposition (CVD) process using plasma of argon and methane gases. During deposition, a d.c. self-bias was applied to the substrates by application of 13.56 MHz rf power.

  18. Transparent conducting film: Effect of mechanical stretching to ...

    Indian Academy of Sciences (India)

    We describe in this paper a transparent conducting film (TCF). It is a fibrous layer of multiwalled carbon nanotubes (MWNTs), labeled a dilute CNT mat, that was prepared and unidirectionally stretched to improve both the optical and electrical properties. After stretching by 80% strain, transmittance at 550 nm wavelength ...

  19. The effect of organoclay type on morphology and mechanical properties of polypropylene films: comparative study

    International Nuclear Information System (INIS)

    Gama, D.B.; Calado, J.F.; Duarte, I.S.; Silva, S.M.L.; Andrade, D.L.A.C.S.

    2012-01-01

    This paper aims to compare the effect of the type of organoclay on morphological and mechanical properties of polypropylene films. Thus, were employed two organobentonite synthesized by NanoPol/UFCG (APOC and APOCF) and a organo montmorillonite Cloisite 20A (C20A) from Southern Clay Products (Texas/USA). The PP films and the PP/organoclay hybrids were prepared in a ChillRoll extruder - 16 AX Plastics and characterized by X-ray diffraction and mechanical properties. The results indicate that the incorporation of organobentonite (APOC and APOCF) and organo montmorillonite (C20A) resulted in the formation of PP nanocomposites with predominantly intercalated morphologies. Also indicate that the mechanical behavior of the films obtained with the three clays (APOC APOCF and C20A) was similar suggesting that the organobentonite, modified with national technology, raw material of low cost when compared to commercial organo montmorillonite, can be a viable alternative in the preparation of PP films. (author)

  20. Mechanical properties of bioplastics cassava starch film with Zinc Oxide nanofiller as reinforcement

    Science.gov (United States)

    Harunsyah; Yunus, M.; Fauzan, Reza

    2017-06-01

    This study focuses on investigating the influence of zinc oxide nanofiller on the mechanical properties of bioplastic cassava starch films. Bioplastic cassava starch film-based zinc oxide reinforced composite biopolymeric films were prepared by casting technique. The content of zinc oxide in the bioplastic films was varied from 0.2%, 0.4%, 0.6%, 0.8% and 1.0% (w/w) by weight of starch. Surface morphologies of the composites bioplastic films were examined by scanning electron microscope (SEM).The result showed that the Tensile strength (TS) was improved significantly with the additional of zinc oxide but the elongation at break (EB %) of the composites was decreased. The maximum tensile strength obtained was 22.30 kgf / mm on the additional of zinc oxide by 0.6% and plastilizer by 25%. Based on data of FTIR, the produced film plastic did not change the group function and it can be concluded that theinteraction in film plastic produced was only a physical interaction. Biodegradable plastic film based on cassava starch-zinc oxide and plasticizer glycerol showed that interesting mechanical properties being transparent, clear, homogeneous, flexible, and easily handled.

  1. Physical and mechanical properties of gelatin-CMC composite films under the influence of electrostatic interactions.

    Science.gov (United States)

    Esteghlal, Sara; Niakousari, Mehrdad; Hosseini, Seyed Mohammad Hashem

    2018-03-17

    The objective of current study was to examine the electrostatic interactions between gelatin and carboxymethyl cellulose (CMC) as a function of pH and mixing ratio (MR) and to observe how the physical and mechanical properties of gelatin-CMC composite films are affected by these interactions. The interaction between biopolymers was studied using turbidometric analysis at different gelatin: CMC MRs and pH values. A reduction in pH and MR enhanced the electrostatic interactions; while, decreased the relative viscosity of mixed system. Physical and mechanical properties of resultant composite films were examined and compared with those of control gelatin films. Changes in the intensity of interactions between the two biopolymers resulted in films with different properties. Polymer complexation led to formation of resistant film networks of less solubility and swellability. Water vapor permeability (WVP) was not significantly (P≤0.05) influenced by incorporating CMC into continuous gelatin films. Composite films prepared at MR of 9:1 and pH opt (corresponding to the maximum amount of interaction) revealed different characteristics such as maximum amounts of WVP and swelling and minimum amounts of tensile strength and solubility. FTIR spectra of composite films confirmed that gelatin and CMC were not covalently bonded. Copyright © 2018. Published by Elsevier B.V.

  2. Hemicelluloses/montmorillonite hybrid films with improved mechanical and barrier properties

    Science.gov (United States)

    Chen, Ge-Gu; Qi, Xian-Ming; Li, Ming-Peng; Guan, Ying; Bian, Jing; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

    2015-11-01

    A facile and environmentally friendly method was introduced to incorporate montmorillonite (MMT) as an inorganic phase into quaternized hemicelluloses (QH) for forming hemicellulose-based films. Two fillers, polyvinyl alcohol (PVA) and chitin nanowhiskers (NCH), were added into the hemicelluloses/MMT hybrid matrices to prepare hybrid films, respectively. The hybrid films were nanocomposites with nacre-like structure and multifunctional characteristics including higher strength and good oxygen barrier properties via the electrostatic and hydrogen bonding interactions. The addition of PVA and NCH could induce changes in surface topography, and effectively enhance mechanical strength, thermal stability, transparency, and oxygen barrier properties. The tensile strengths of the composite films FPVA(0.3), FPVA(0.5), and FNCH(0.8) were 53.7, 46.3, and 50.1 MPa, respectively, which were 171%, 134%, and 153% larger than the FQH-MMT film (19.8 MPa). The tensile strength, and oxygen transmission rate of QH-MMT-PVA film were better than those of quaternized hemicelluloses/MMT films. Thus, the proper filler is very important for the strength of the hybrid film. These results provide insights into the understanding of the structural relationships of hemicellulose-based composite films in coating and packaging application for the future.

  3. Effect of substrate on texture and mechanical properties of Mg-Cu-Zn thin films

    Science.gov (United States)

    Eshaghi, F.; Zolanvari, A.

    2018-04-01

    In this work, thin films of Mg-Cu-Zn with 60 nm thicknesses have been deposited on the Si(100), Al, stainless steel, and Cu substrates using DC magnetron sputtering. FESEM images displayed uniformity of Mg-Cu-Zn particles on the different substrates. AFM micrograph revealed the roughness of thin film changes due to the different kinds of the substrates. XRD measurements showed the existence of strong Mg (002) reflections and weak Mg (101) peaks. Residual stress and adhesion force have been measured as the mechanical properties of the Mg-Cu-Zn thin films. The residual stresses of thin films which have been investigated by X-ray diffraction method revealed that the thin films sputtered on the Si and Cu substrates endure minimum and maximum stresses, respectively, during the deposition process. However, the force spectroscopy analysis indicated that the films grew on the Si and Cu experienced maximum and minimum adhesion force. The texture analysis has been done using XRD instrument to make pole figures of Mg (002) and Mg (101) reflections. ODFs have been calculated to evaluate the distribution of the orientations within the thin films. It was found that the texture and stress have an inverse relation, while the texture and the adhesion force of the Mg-Cu-Zn thin films have direct relation. A thin film that sustains the lowest residual stresses and highest adhesive force had the strongest {001} basal fiber texture.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  5. Characterization of starch films containing starch nanoparticles: part 1: physical and mechanical properties.

    Science.gov (United States)

    Shi, Ai-Min; Wang, Li-Jun; Li, Dong; Adhikari, Benu

    2013-07-25

    We report, for the first time, the preparation method and characteristics of starch films incorporating spray dried and vacuum freeze dried starch nanoparticles. Physical properties of these films such as morphology, crystallinity, water vapor permeability (WVP), opacity, and glass transition temperature (Tg) and mechanical properties (strain versus temperature, strain versus stress, Young's modulus and toughness) were measured. Addition of both starch nanoparticles in starch films increased roughness of surface, lowered degree of crystallinity by 23.5%, WVP by 44% and Tg by 4.3°C, respectively compared to those of starch-only films. Drying method used in preparation of starch nanoparticles only affected opacity of films. The incorporation of nanoparticles in starch films resulted into denser films due to which the extent of variation of strain with temperature was much lower. The toughness and Young's modulus of films containing both types of starch nanoparticles were lower than those of control films especially at <100°C. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Fabrication and mechanical characterization of biodegradable and synthetic polymeric films: Effect of gamma radiation

    Science.gov (United States)

    Akter, Nousin; Khan, Ruhul A.; Salmieri, Stephane; Sharmin, Nusrat; Dussault, Dominic; Lacroix, Monique

    2012-08-01

    Chitosan (1 wt%, in 2% aqueous acetic acid solution) and starch (1 wt%, in deionised water) were dissolved and mixed in different proportions (20-80 wt% chitosan) then films were prepared by casting. Tensile strength and elongation at break of the 50% chitosan containing starch-based films were found to be 47 MPa and 16%, respectively. It was revealed that with the increase of chitosan in starch, the values of TS improved significantly. Monomer, 2-butane diol-diacrylate (BDDA) was added into the film forming solutions (50% starch-based), then casted films. The BDDA containing films were irradiated under gamma radiation (5-25 kGy) and it was found that strength of the films improved significantly. On the other hand, synthetic petroleum-based polymeric films (polycaprolactone, polyethylene and polypropylene) were prepared by compression moulding. Mechanical and barrier properties of the films were evaluated. The gamma irradiated (25 kGy) films showed higher strength and better barrier properties.

  7. Thermally evaporated mechanically hard tin oxide thin films for opto-electronic apllications

    Energy Technology Data Exchange (ETDEWEB)

    Tripathy, Sumanta K.; Rajeswari, V. P. [Centre for Nano Science and Technology, GVP College of Engineering (Autonomous), Visakhapatnam- 530048 (India)

    2014-01-28

    Tungsten doped tin oxide (WTO) and Molybdenum doped tin oxide (MoTO) thin film were deposited on corn glass by thermal evaporation method. The films were annealed at 350°C for one hour. Structural analysis using Xray diffraction data shows both the films are polycrystalline in nature with monoclinic structure of tin oxide, Sn{sub 3}O{sub 4}, corresponding to JCPDS card number 01-078-6064. SEM photograph showed that both the films have spherical grains with size in the range of 20–30 nm. Compositional analysis was carried out using EDS which reveals the presence of Sn, O and the dopant Mo/W only thereby indicating the absence of any secondary phase in the films. The films are found to contain nearly 6 wt% of Mo, 8 wt% of W as dopants respectively. The transmission pattern for both the films in the spectral range 200 – 2000 nm shows that W doping gives a transparency of nearly 80% from 380 nm onwards while Mo doping has less transparency of 39% at 380nm. Film hardness measurement using Triboscope shows a film hardness of about 9–10 GPa for both the films. It indicates that W or M doping in tin oxide provides the films the added advantage of withstanding the mechanical wear and tear due to environmental fluctuations By optimizing the optical and electrical properties, W/Mo doped tin oxide films may be explored as window layers in opto-electronic applications such as solar cells.

  8. Stress-driven lithium dendrite growth mechanism and dendrite mitigation by electroplating on soft substrates

    Science.gov (United States)

    Wang, Xu; Zeng, Wei; Hong, Liang; Xu, Wenwen; Yang, Haokai; Wang, Fan; Duan, Huigao; Tang, Ming; Jiang, Hanqing

    2018-03-01

    Problems related to dendrite growth on lithium-metal anodes such as capacity loss and short circuit present major barriers to next-generation high-energy-density batteries. The development of successful lithium dendrite mitigation strategies is impeded by an incomplete understanding of the Li dendrite growth mechanisms, and in particular, Li-plating-induced internal stress in Li metal and its effect on Li growth morphology are not well addressed. Here, we reveal the enabling role of plating residual stress in dendrite formation through depositing Li on soft substrates and a stress-driven dendrite growth model. We show that dendrite growth is mitigated on such soft substrates through surface-wrinkling-induced stress relaxation in the deposited Li film. We demonstrate that this dendrite mitigation mechanism can be utilized synergistically with other existing approaches in the form of three-dimensional soft scaffolds for Li plating, which achieves higher coulombic efficiency and better capacity retention than that for conventional copper substrates.

  9. Microcoupon Assay Of Adhesion And Growth Of Bacterial Films

    Science.gov (United States)

    Pierson, Duane L.; Koenig, David W.

    1994-01-01

    Microbiological assay technique facilitates determination of some characteristics of sessile bacteria like those that attach to and coat interior walls of water-purification systems. Biofilms cause sickness and interfere with purification process. Technique enables direct measurement of rate of attachment of bacterial cells, their metabolism, and effects of chemicals on them. Used to quantify effects of both bactericides and growth-stimulating agents and in place of older standard plate-count and tube-dilution techniques.

  10. Crystalline silicon thin film growth by ECR plasma CVD for solar cells

    International Nuclear Information System (INIS)

    Licai Wang

    1999-07-01

    This thesis describes the background, motivation and work carried out towards this PhD programme entitled 'Crystalline Silicon Thin Film Growth by ECR Plasma CVD for Solar Cells'. The fundamental principles of silicon solar cells are introduced with a review of silicon thin film and bulk solar cells. The development and prospects for thin film silicon solar cells are described. Some results of a modelling study on thin film single crystalline solar cells are given which has been carried out using a commercially available solar cell simulation package (PC-1D). This is followed by a description of thin film deposition techniques. These include Chemical Vapour Deposition (CVD) and Plasma-Assisted CVD (PACVD). The basic theory and technology of the emerging technique of Electron Cyclotron Resonance (ECR) PACVD, which was used in this research, are introduced and the potential advantages summarised. Some of the basic methods of material and cell characterisation are briefly described, together with the work carried out in this research. The growth by ECR PACVD at temperatures 2 illumination. The best efficiency in the ECR grown structures was 13.76% using an epitaxial emitter. Cell performance was analysed in detail and the factors controlling performance identified by fitting self-consistently the fight and dark current-voltage and spectral response data using PC-1D. Finally, the conclusions for this research and suggestions for further work are outlined. (author)

  11. In situ X-ray synchrotron study of organic semiconductor ultra-thin films growth

    International Nuclear Information System (INIS)

    Moulin, J.-F.; Dinelli, F.; Massi, M.; Albonetti, C.; Kshirsagar, R.; Biscarini, F.

    2006-01-01

    In this work we present an X-ray diffraction study of the early stages of growth of an organic semiconductor (sexithiophene, T 6 ) thin film prepared by high vacuum sublimation. Specular reflectometry and grazing incidence X-ray diffraction were used to monitor the formation of T 6 films on silicon oxide. Our results show that T 6 grows as a crystalline layer from the beginning of the evaporation. The reflectometry analysis suggests that, in the range of rates and temperatures studied, the growth is never layer by layer but rather 3D in nature. In-plane GIXD has allowed us to observe for the first time a thin film phase of T 6 formed of molecules standing normal to the substrate and arranged in a compressed unit cell with respect to the bulk, i.e. the unit cell parameters b and c are relatively smaller. We have followed the dynamics of formation of this new phase and identified the threshold of appearance of the bulk phase, which occurs above ∼5-6 monolayers. These results are relevant to the problem of organic thin film transistors, for which we have previously demonstrated experimentally that only the first two monolayers of T 6 films are involved in the electrical transport. The layers above the second one do not effectively contribute to charge mobility, either because they are more 'disordered' or because of a screening of the gate field

  12. Direct Measurement of Crazing Mechanics in Polystyrene Thin Films: Molecular Weight Effects

    Science.gov (United States)

    Shimomura, Shinichiro; Bay, Reed; Ilton, Mark; Crosby, Alfred

    Mechanical properties of polymer thin films are critical to various applications such as protective coatings, electronic devices, and separation membranes. Although methods for measuring the structure and some physical properties, such as Tg, of polymer thin films have been well established, measuring mechanical properties of thin films has not been fully developed and has been largely limited to extremely small strains and complex stress distributions. To overcome these limitations, we have recently introduced a direct measurement technique for quantifying the complete uniaxial stress-strain relationship for polymer thin films. Here, we use `dog-bone' shaped thin films of polystyrene (PS) to quantify the change in mechanical response as a function of molecular weight. We observe a nonlinear stress-strain relationship, resembling ideal plastic-like behavior, associated with the onset of crazing. We will discuss how the onset stress and critical strain to failure changes as a function of molecular weight. These changes, and the alignment of craze fibrils, are discussed in the context of how entanglement density is altered for confined thin films. These results provide new insight into fundamental molecular physics for polymer thin films.

  13. Mechanical characterization of yeast cells: effects of growth conditions.

    Science.gov (United States)

    Overbeck, A; Kampen, I; Kwade, A

    2015-10-01

    Industrial biotechnology uses microbiological cells to produce a wide range of products. While the organisms in question are well understood regarding their genetic and molecular properties, less is known about their mechanical properties. Previous work has established a testing procedure for single Saccharomyces cerevisiae cells using a Nanoindenter equipped with a Flat Punch probe, allowing the compression between two parallel surfaces. The resulting force-displacement curves clearly showed the bursting of the cells and served to determine characteristic values such as the bursting force, bursting energy and relative deformation. This study examined the mechanical characteristics of yeast cells under the influence of varying cultivation parameters, namely the pH value, temperature, aeration rate, stirrer speed and culture medium composition. It was observed that only temperature and medium composition showed significant effect on the mechanical properties of the cells. Higher temperatures during cultivation caused lower bursting forces and energies. Further analysis of the data showed that the mechanical characteristics of the cells were only influenced by parameters which also had an influence on the growth rate. In conclusion, higher growth rates result in a lower mechanical strength of the yeast cells. This study provides data on the influence of growth conditions on the mechanical properties of yeast cells. Single cell compression tests on Saccharomyces cerevisiae cells indicate that higher growth rates result in a lower mechanical strength of the cells. As in biotechnological processes mechanical degradation is often part of the downstream process to release the product from the micro-organisms, the knowledge about the mechanical properties of the cells is relevant for process optimization. © 2015 The Society for Applied Microbiology.

  14. Growth limit of carbon onions – A continuum mechanical study

    DEFF Research Database (Denmark)

    Todt, Melanie; Bitsche, Robert; Hartmann, Markus A.

    2014-01-01

    The growth of carbon onions is simulated using continuum mechanical shell models. With this models it is shown that, if a carbon onion has grown to a critical size, the formation of an additional layer leads to the occurrence of a structural instability. This instability inhibits further growth o...... model gives insight into mechanisms which are assumed to limit the size of carbon onions and can serve as basis for further investigations, e.g., of the formation of nanodiamonds in the center of carbon onions. © 2013 Elsevier Ltd. All rights reserved....

  15. Nanohybrid shish kebab paper: Crystal growth and film properties

    Science.gov (United States)

    Laird, Eric D.; Li, Bing; Cheng, Shan; Dong, Bin; Bose, Ranjita K.; Lau, Kenneth K. S.; Li, Christopher Y.

    2012-02-01

    Polyethylene single crystals were uniformly grown heterogeneously from carbon nanotubes (CNTs) in solution, forming the nanohybrid shish kebab (NHSK) structure. We demonstrate that highly uniform, free-standing nanohybrid buckypaper with high CNT contents (13-70%) could be produced from vacuum-filtrated polymer single crystal-decorated CNTs. In this way, polymer crystals served as unique spacers for CNTs so that uniform hybrid buckypaper films could be obtained without CNT agglomeration. Wetting techniques, thermal analysis, and scanning electron microscopy were used to elucidate the effect of polymer single crystals on the resultant structure. Surface roughness of NHSK paper could be controlled by tuning the polymer single crystal size (CNT separation distance). Superhydrophobic NHSK papers were obtained with high surface adhesion, which mimics the rose petal effect. Conductivity of the NHSK papers also varied with polymer crystal size. Great enhancement of important properties could be achieved through the formation of ternary hybrids. To that end, initiated- and oxidative chemical vapor deposition methods extend NHSK buckypaper applicability by providing functional polymer surfaces. NHSK papers may find applications in sensors, electrochemical devices and coatings.

  16. Real-time growth study of plasma assisted atomic layer epitaxy of InN films by synchrotron x-ray methods

    Energy Technology Data Exchange (ETDEWEB)

    Nepal, Neeraj [U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375; Anderson, Virginia R. [American Society for Engineering Education, 1818 N Street NW, Washington, DC 20036; Johnson, Scooter D. [U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375; Downey, Brian P. [U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375; Meyer, David J. [U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375; DeMasi, Alexander [Physics Department, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215; Robinson, Zachary R. [Department of Physics, SUNY College at Brockport, 350 New Campus Dr, Brockport, New York 14420; Ludwig, Karl F. [Physics Department, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215; Eddy, Charles R. [U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375

    2017-03-13

    The temporal evolution of high quality indium nitride (InN) growth by plasma-assisted atomic layer epitaxy (ALEp) on a-plane sapphire at 200 and 248 °C was probed by synchrotron x-ray methods. The growth was carried out in a thin film growth facility installed at beamline X21 of the National Synchrotron Light Source at Brookhaven National Laboratory and at beamline G3 of the Cornell High Energy Synchrotron Source, Cornell University. Measurements of grazing incidence small angle x-ray scattering (GISAXS) during the initial cycles of growth revealed a broadening and scattering near the diffuse specular rod and the development of scattering intensities due to half unit cell thick nucleation islands in the Yoneda wing with correlation length scale of 7.1 and 8.2 nm, at growth temperatures (Tg) of 200 and 248 °C, respectively. At about 1.1 nm (two unit cells) of growth thickness nucleation islands coarsen, grow, and the intensity of correlated scattering peak increased at the correlation length scale of 8.0 and 8.7 nm for Tg = 200 and 248 °C, respectively. The correlated peaks at both growth temperatures can be fitted with a single peak Lorentzian function, which support single mode growth. Post-growth in situ x-ray reflectivity measurements indicate a growth rate of ~0.36 Å/cycle consistent with the growth rate previously reported for self-limited InN growth in a commercial ALEp reactor. Consistent with the in situ GISAXS study, ex situ atomic force microscopy power spectral density measurements also indicate single mode growth. Electrical characterization of the resulting film revealed an electron mobility of 50 cm2/V s for a 5.6 nm thick InN film on a-plane sapphire, which is higher than the previously reported mobility of much thicker InN films grown at higher temperature by molecular beam epitaxy directly on sapphire. These early results indicated that in situ synchrotron x-ray study of the epitaxial growth kinetics of InN films is a very powerful method to

  17. Thin film solar cells from earth abundant materials growth and characterization of Cu2(ZnSn)(SSe)4 thin films and their solar cells

    CERN Document Server

    Kodigala, Subba Ramaiah

    2013-01-01

    The fundamental concept of the book is to explain how to make thin film solar cells from the abundant solar energy materials by low cost. The proper and optimized growth conditions are very essential while sandwiching thin films to make solar cell otherwise secondary phases play a role to undermine the working function of solar cells. The book illustrates growth and characterization of Cu2ZnSn(S1-xSex)4 thin film absorbers and their solar cells. The fabrication process of absorber layers by either vacuum or non-vacuum process is readily elaborated in the book, which helps for further developm

  18. Composition and growth procedure-dependent properties of electrodeposited CuInSe 2 thin films

    Science.gov (United States)

    Babu, S. Moorthy; Ennaoui, A.; Lux-Steiner, M. Ch.

    2005-02-01

    CuInSe 2 thin films were deposited on molybdenum-coated glass substrates by electrodeposition. Deposition was carried out with a variety of electrochemical bath compositions. The quality of the deposits depends very much on the source materials as well as the concentration of the same in the electrolyte. The deposition potential was varied from -0.4 to -0.75 V vs. SCE. The pH of the solution was adjusted to 1.5-2 using diluted sulphuric acid. Chloride salts containing bath yield good surface morphology, but there is always excess of the metallic content in the deposited films. Different growth procedures, like initial metallic layers of copper or indium, layers of copper selenide or indium selenide before the actual deposition of ternary chalcopyrite layers were attempted. Fabrication pathway, morphological and compositional changes due to the different precursor route has been analysed. The quality of the deposits prepared by one-step electrodeposition is better than the deposits with a two-stage process. The deposited films were characterized with XRD, SEM-EDAX, UV-visible spectroscopy and I- V characteristics. The deposited films were annealed in air as well as in nitrogen atmosphere. The influence of annealing temperature, environment and annealing time on the properties of the films are evaluated. Attempts were made to fabricate solar cell structure from the deposited absorber films. The structure of Mo/CuInSe 2/CdS/ZnO/Ni was characterized with surface, optical and electrical studies.

  19. Growth of cubic and hexagonal CdTe thin films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, S.K. [Solid State Physics Laboratory, Lucknow Road, Timarpur, Delhi 110 054 (India)]. E-mail: 628@ssplnet.org; Tiwari, Umesh [Solid State Physics Laboratory, Lucknow Road, Timarpur, Delhi 110 054 (India); Raman, R. [Solid State Physics Laboratory, Lucknow Road, Timarpur, Delhi 110 054 (India); Prakash, Chandra [Solid State Physics Laboratory, Lucknow Road, Timarpur, Delhi 110 054 (India); Krishna, Vamsi [Centre for Energy Studies, Indian Institute of Technology, New Delhi 110 016 (India); Dutta, Viresh [Centre for Energy Studies, Indian Institute of Technology, New Delhi 110 016 (India); Zimik, K. [Laser Science and Technology Centre, Metcalfe House, Delhi 110 054 (India)

    2005-02-01

    The paper reports the growth of cadmium telluride (CdTe) thin films by pulsed laser deposition (PLD) using excimer laser (KrF, {lambda}=248 nm, 10 Hz) on corning 7059 glass and SnO{sub 2}-coated glass (SnO{sub 2}/glass) substrates at different substrate temperatures (T{sub s}) and at different laser energy pulses. Single crystal target CdTe was used for deposition of thin films. With 30 min deposition time, 1.8- to {approx}3-{mu}m-thick films were obtained up to 200 deg. C substrate temperature. However, the film re-evaporates from the substrate surface at temperatures >275 deg. C. Atomic force microscopy (AFM) shows an average grain size {approx}0.3 {mu}m. X-ray diffraction analysis confirms the formation of CdTe cubic phase at all pulse energies except at 200 mJ. At 200 mJ laser energy, the films show hexagonal phase. Optical properties of CdTe were also investigated and the band gap of CdTe films were found as 1.54 eV for hexagonal phase and {approx}1.6 eV for cubic phase.

  20. Substrate structure dependence of the growth modes of p-quaterphenyl thin films on gold

    International Nuclear Information System (INIS)

    Muellegger, S.; Mitsche, S.; Poelt, P.; Haenel, K.; Birkner, A.; Woell, C.; Winkler, A.

    2005-01-01

    The variably oriented crystallite surfaces of a recrystallized polycrystalline gold sample served as substrates for the investigation of the structure dependence of p-quaterphenyl (4P) thin film growth. The films were prepared in ultrahigh vacuum by organic molecular beam evaporation. Optical microscopy, scanning electron microscopy, combined with laterally resolved electron backscatter diffraction and scanning tunnelling microscopy have been applied to determine the correlation between the substrate surface structure and 4P film morphology. Crystallite surfaces consisting of (110) terraces favour highly anisotropic needle-like 4P growth with the needle orientation normal to the Au directions. Atomic steps on vicinal planes with narrow terraces (< 2 nm) can also induce anisotropy in the 4P thin film growth, in particular elongated 4P islands normal to the step direction. In contrast to that, a nearly isotropic distribution of the needle orientations is observed on Au grains terminated by highly symmetric (111) or (100) crystal planes. Additionally, patches of continuous 4P layers can be found on these surfaces. There is strong evidence that the 4P molecules within the needle-like crystallites are oriented parallel to the Au surface, whereas for the continuous layers the 4P molecules are oriented nearly upright on the surface

  1. Mechanisms of oxygen permeation through plastic films and barrier coatings

    Science.gov (United States)

    Wilski, Stefan; Wipperfürth, Jens; Jaritz, Montgomery; Kirchheim, Dennis; Mitschker, Felix; Awakowicz, Peter; Dahlmann, Rainer; Hopmann, Christian

    2017-10-01

    Oxygen and water vapour permeation through plastic films in food packaging or other applications with high demands on permeation are prevented by inorganic barrier films. Most of the permeation occurs through small defects (PET) are investigated and the mass transport through the polymer is simulated in a 3D approach. Calculations of single defects showed that there is no linear correlation between the defect area and the resulting permeability. The influence of adjacent defects in different distances was observed and led to flow reduction functions depending on the defect spacing and defect area. A critical defect spacing where no interaction between defects occurs was found and compared to other findings. According to the superposition principle, the permeability of single defects was added up and compared to experimentally determined oxygen permeation. The results showed the same trend of decreasing permeability with decreasing defect densities.

  2. Physico-mechanical and structural properties of eggshell membrane gelatin- chitosan blend edible films.

    Science.gov (United States)

    Mohammadi, Reza; Mohammadifar, Mohammad Amin; Rouhi, Milad; Kariminejad, Mohaddeseh; Mortazavian, Amir Mohammad; Sadeghi, Ehsan; Hasanvand, Sara

    2018-02-01

    This study investigated the physico-mechanical and structural properties of composite edible films based on eggshell membrane gelatin (G) and chitosan (Ch) (75G:25Ch, 50G:50Ch, 25G:75Ch). The results demonstrated that the addition of Ch increased elongation at break significantly (pfilm. The water solubility and water vapor permeability of the 50G:50Ch film decreased significantly compared to plain films (100G:0Ch and 0G:100Ch) and other composite films (pfilms; it revealed a homogenous and compact structure in 75G:25Ch and 50G:50 Ch. Also, the chemical interactions introduced by the addition of chitosan to eggshell membrane gelatin as new resources could improve the films' functional properties. Copyright © 2017. Published by Elsevier B.V.

  3. Composite Films of Arabinoxylan and Fibrous Sepiolite: Morphological, Mechanical, and Barrier Properties

    DEFF Research Database (Denmark)

    Sárossy, Zsuzsa; Blomfeldt, J.O.; Hedenqvist, Mikael S.

    2012-01-01

    in the arabinoxylan films and sepiolite fiber aggregation was not found. FT-IR spectroscopy provided some evidence for hydrogen bonding between sepiolite and arabinoxylan. Consistent with these findings, mechanical testing showed increases in film stiffness and strength with sepiolite addition and the effect of poly......Hemicelluloses represent a largely unutilized resource for future bioderived films in packaging and other applications. However, improvement of film properties is needed in order to transfer this potential into reality. In this context, sepiolite, a fibrous clay, was investigated as an additive...... to enhance the properties of rye flour arabinoxylan. Composite films cast from arabinoxylan solutions and sepiolite suspensions in water were transparent or semitransparent at additive loadings in the 2.5−10 wt % range. Scanning electron microscopy showed that the sepiolite was well dispersed...

  4. Atomic force microscopy measurements of crystal nucleation and growth rates in thin films of amorphous Te alloys

    Science.gov (United States)

    Kalb, J.; Spaepen, F.; Wuttig, M.

    2004-06-01

    Ex situ atomic force microscopy in combination with a high-precision furnace has been employed for a systematic study of crystallization kinetics of sputtered amorphous Ag0.055In0.065Sb0.59Te0.29, Ge4Sb1Te5, and Ge2Sb2Te5 thin films used for optical data storage. Direct observation of crystals enabled us to establish the temperature dependence of the crystal nucleation rate and crystal growth velocity around 150°C. While these alloys exhibited similar crystal growth characteristics, the crystal nucleation behavior of Ag0.055In0.065Sb0.59Te0.29 differed significantly from that of Ge4Sb1Te5 and Ge2Sb2Te5. These observations provide an explanation for the different recrystallization mechanisms observed upon laser heating of amorphous marks.

  5. Controlled Mechanical Cracking of Metal Films Deposited on Polydimethylsiloxane (PDMS

    Directory of Open Access Journals (Sweden)

    Andreas Polywka

    2016-09-01

    Full Text Available Stretchable large area electronics conform to arbitrarily-shaped 3D surfaces and enables comfortable contact to the human skin and other biological tissue. There are approaches allowing for large area thin films to be stretched by tens of percent without cracking. The approach presented here does not prevent cracking, rather it aims to precisely control the crack positions and their orientation. For this purpose, the polydimethylsiloxane (PDMS is hardened by exposure to ultraviolet radiation (172 nm through an exposure mask. Only well-defined patterns are kept untreated. With these soft islands cracks at the hardened surface can be controlled in terms of starting position, direction and end position. This approach is first investigated at the hardened PDMS surface itself. It is then applied to conductive silver films deposited from the liquid phase. It is found that statistical (uncontrolled cracking of the silver films can be avoided at strain below 35%. This enables metal interconnects to be integrated into stretchable networks. The combination of controlled cracks with wrinkling enables interconnects that are stretchable in arbitrary and changing directions. The deposition and patterning does not involve vacuum processing, photolithography, or solvents.

  6. TiN films by Atomic Layer Deposition: Growth and electrical characterization down to sub-nm thickness

    NARCIS (Netherlands)

    Van Hao, B.; Wolters, Robertus A.M.; Kovalgin, Alexeij Y.

    2012-01-01

    This study reports on the growth and characterization of TiN thib films obtained by atomic layer deposition at 350-425 ◦C. We observe a growth of the continuous layers from the very beginning of the process, i.e. for a thickness of 0.65 nm, which is equivalent to 3 monolayers of TiN. The film growth

  7. Effect of size and moisture on the mechanical behavior of SU-8 thin films

    International Nuclear Information System (INIS)

    Robin, C J; Jonnalagadda, K N

    2016-01-01

    The mechanical properties of SU-8 were investigated in conjunction with size effect, mechanical anisotropy and moisture absorption. Uniaxial tensile experiments were conducted on SU-8 films of 500 nm and 2 μm thickness. A spin coating process was used to fabricate the films with one set from a single coat (single layer) and the others containing multiple coats (multilayer) with pre-baking in between. The stress versus strain response was obtained from in situ optical experiments and a digital image correlation method. Compared to single layer films, the multilayer films showed a significant increase in mechanical properties as well as in-plane anisotropy. This anisotropy was confirmed using Fourier transform infrared spectroscopy and attributed to the spin coating process, which resulted in higher crosslinking density in the film, and molecular orientation in the radial direction. Moisture absorption studies revealed that the mechanical properties were affected by water, which exists in both the free and bonded form in the polymer and acts as a plasticizer. The effect of moisture was similar in both the single and multilayer films, but was higher for the latter due to multiple processing steps as well as the existence of higher percentage of epoxy polar groups. (paper)

  8. Mechanisms and applications of plant growth promoting rhizobacteria: Current perspective

    Directory of Open Access Journals (Sweden)

    Munees Ahemad

    2014-01-01

    Full Text Available Plant growth promoting rhizobacteria are the soil bacteria inhabiting around/on the root surface and are directly or indirectly involved in promoting plant growth and development via production and secretion of various regulatory chemicals in the vicinity of rhizosphere. Generally, plant growth promoting rhizobacteria facilitate the plant growth directly by either assisting in resource acquisition (nitrogen, phosphorus and essential minerals or modulating plant hormone levels, or indirectly by decreasing the inhibitory effects of various pathogens on plant growth and development in the forms of biocontrol agents. Various studies have documented the increased health and productivity of different plant species by the application of plant growth promoting rhizobacteria under both normal and stressed conditions. The plant-beneficial rhizobacteria may decrease the global dependence on hazardous agricultural chemicals which destabilize the agro-ecosystems. This review accentuates the perception of the rhizosphere and plant growth promoting rhizobacteria under the current perspectives. Further, explicit outlooks on the different mechanisms of rhizobacteria mediated plant growth promotion have been described in detail with the recent development and research. Finally, the latest paradigms of applicability of these beneficial rhizobacteria in different agro-ecosystems have been presented comprehensively under both normal and stress conditions to highlight the recent trends with the aim to develop future insights.

  9. Growth of highly uniform, reproducible InGaAs films in a multiwafer rotating disk reactor by MOCVD

    Science.gov (United States)

    McKee, M. A.; Norris, P. E.; Stall, R. A.; Tompa, G. S.; Chern, C. S.; Noh, D.; Kang, S. S.; Jasinski, T. J.

    1991-01-01

    Much of the work on InGaAs film growth has been limited to small single wafer systems with little reported information on the wafer-to-wafer and run-to-run repeatability of the films. We report here on the growth of highly uniform films in a multiwafer system with good run-to-run repeatability. The uniformity of the film properties across the susceptor results from the careful design of the reaction chamber using fluid dynamical modeling. The control of the composition during the course of the run and from run-to-run was improved by careful design of the trimethylindium solid source container.

  10. In situ growth of p and n-type graphene thin films and diodes by pulsed laser deposition

    KAUST Repository

    Sarath Kumar, S. R.

    2013-11-07

    We report the in situ growth of p and n-type graphene thin films by ultraviolet pulsed laser deposition in the presence of argon and nitrogen, respectively. Electron microscopy and Raman studies confirmed the growth, while temperature dependent electrical conductivity and Seebeck coefficient studies confirmed the polarity type of graphene films. Nitrogen doping at different sites of the honeycomb structure, responsible for n-type conduction, is identified using X-ray photoelectron spectroscopy, for films grown in nitrogen. A diode-like rectifying behavior is exhibited by p-n junction diodes fabricated using the graphene films.

  11. Two different mechanisms on UV emission enhancement in Ag-doped ZnO thin films

    International Nuclear Information System (INIS)

    Xu, Linhua; Zheng, Gaige; Zhao, Lilong; Pei, Shixin

    2015-01-01

    Ag-doped ZnO thin films were prepared by a sol–gel method. The structural, morphological and optical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis and photoluminescence spectra. The results show that the Ag in the ZnO thin films annealed at 500 °C for 1 h substitutes for Zn and exists in the form of Ag + ion (Ag Zn ) while the Ag in the ZnO thin films without a post-annealing mainly exists in the form of simple substance (Ag 0 ). The incorporation of Ag indeed can improve the ultraviolet emission of ZnO thin films and suppress the visible emissions at the same time. However, the mechanisms on the ultraviolet emission enhancement in the annealed and unannealed Ag-doped ZnO thin films are very different. As for the post-annealed Ag-doped ZnO thin films, the UV emission enhancement maybe mainly results from more electron–hole pairs (excitons) due to Ag-doping while for the unannealed Ag-doped ZnO thin films; the UV emission enhancement is attributed to the resonant coupling between exciton emission in ZnO and localized surface plasmon in Ag nanoparticles. - Highlights: • Ag-doped ZnO thin films have been prepared by the sol–gel method. • Ag-doping can enhance ultraviolet emission of ZnO thin films and depress the visible emissions at the same time. • There are two different mechanisms on UV emission enhancement in Ag-doped ZnO thin films. • The UV emission enhancement from the resonant coupling between excitonic emissions and localized surface plasmon in Ag nanoparticle is very attractive

  12. Contributions of evaporation and other mechanisms to tear film thinning and break-up.

    Science.gov (United States)

    King-Smith, P Ewen; Nichols, Jason J; Nichols, Kelly K; Fink, Barbara A; Braun, Richard J

    2008-08-01

    To evaluate the contribution of three mechanisms-evaporation of the tear film, inward flow of water into the corneal epithelium or contact lens, and "tangential flow" along the surface of epithelium or contact lens-to the thinning of the tear film between blinks and to tear film break-up. In addition to a discussion of relevant studies, some previously unpublished images are presented illustrating aspects of tear film break-up. CONTRIBUTIONS OF THREE MECHANISMS TO TEAR FILM BREAK-UP: Inward flow of water into the epithelium or contact lens is probably unimportant, and a small flow in the opposite direction may actually occur. Tangential flow is probably important in certain special cases of tear film break-up-at the black line near the tear meniscus, over surface elevations, after partial blinks, and from small thick lipid spots in the tear film. In all these special cases it is argued that tangential flow is important initially, but evaporation may be needed for final thinning to break-up. It is argued that most of the observed tear film thinning between blinks is due to evaporation, rather than tangential flow, and that large "pool" break-up regions are the result of evaporation over an extended area. Evaporation in our "free-air" conditions may be four to five times faster than the average of the values reported in the literature when air currents are prevented by preocular chambers. However, recent evaporation measurements using "ventilated chambers" give higher values, which may correspond better to free-air conditions. Thus evaporation may be fast enough to explain many cases of tear film break-up, and to give rise to considerable increases in the local osmolarity of the tear film between blinks.

  13. Quantifying mechanical force in axonal growth and guidance

    Directory of Open Access Journals (Sweden)

    Ahmad Ibrahim Mahmoud Athamneh

    2015-09-01

    Full Text Available Mechanical force plays a fundamental role in neuronal development, physiology, and regeneration. In particular, research has shown that force is involved in growth cone-mediated axonal growth and guidance as well as stretch-induced elongation when an organism increases in size after forming initial synaptic connections. However, much of the details about the exact role of force in these fundamental processes remain unknown. In this review, we highlight (1 standing questions concerning the role of mechanical force in axonal growth and guidance and (2 different experimental techniques used to quantify forces in axons and growth cones. We believe that satisfying answers to these questions will require quantitative information about the relationship between elongation, forces, cytoskeletal dynamics, axonal transport, signaling, substrate adhesion, and stiffness contributing to directional growth advance. Furthermore, we address why a wide range of force values have been reported in the literature, and what these values mean in the context of neuronal mechanics. We hope that this review will provide a guide for those interested in studying the role of force in development and regeneration of neuronal networks.

  14. Growth Mechanism of Pumpkin-Shaped Vaterite Hierarchical Structures

    Science.gov (United States)

    Ma, Guobin; Xu, Yifei; Wang, Mu

    2015-03-01

    CaCO3-based biominerals possess sophisticated hierarchical structures and promising mechanical properties. Recent researches imply that vaterite may play an important role in formation of CaCO3-based biominerals. However, as a less common polymorph of CaCO3, the growth mechanism of vaterite remains not very clear. Here we report the growth of a pumpkin-shaped vaterite hierarchical structure with a six-fold symmetrical axis and lamellar microstructure. We demonstrate that the growth is controlled by supersaturation and the intrinsic crystallographic anisotropy of vaterite. For the scenario of high supersaturation, the nucleation rate is higher than the lateral extension rate, favoring the ``double-leaf'' spherulitic growth. Meanwhile, nucleation occurs preferentially in as determined by the crystalline structure of vaterite, modulating the grown products with a hexagonal symmetry. The results are beneficial for an in-depth understanding of the biomineralization of CaCO3. The growth mechanism may also be applicable to interpret the formation of similar hierarchical structures of other materials. The authors gratefully acknowledge the financial support from National Science Foundation of China (Grant Nos. 51172104 and 50972057) and National Key Basic Research Program of China (Grant No. 2010CB630705).

  15. Physical, mechanical and barrier properties of corn starch films incorporated with plant essential oils.

    Science.gov (United States)

    Ghasemlou, Mehran; Aliheidari, Nahal; Fahmi, Ronak; Shojaee-Aliabadi, Saeedeh; Keshavarz, Behnam; Cran, Marlene J; Khaksar, Ramin

    2013-10-15

    Corn starch-based films are inherently brittle and lack the necessary mechanical integrity for conventional packaging. However, the incorporation of additives can potentially improve the mechanical properties and processability of starch films. In this work two essential oils, Zataria multiflora Boiss (ZEO) or Mentha pulegium (MEO) at three levels (1%, 2% and 3% (v/v)), were incorporated into starch films using a solution casting method to improve the mechanical and water vapor permeability (WVP) properties and to impart antimicrobial activity. Increasing the content of ZEO or MEO from 2% to 3% (v/v) increased values for elongation at break from 94.38% to 162.45% and from 53.34% to 107.71% respectively, but did not significantly change tensile strength values of the films. The WVP properties of the films decreased from 7.79 to 3.37 or 3.19 g mm m(-2) d(-1) kPa(-1) after 3% (v/v) ZEO or MEO incorporation respectively. The oxygen barrier properties were unaffected at the 1% and 2% (v/v) oil concentration used but oxygen transmission increased with 3% (v/v) for both formulations. The films' color became slightly yellow as the levels of ZEO or MEO were increased although transparency was maintained. Both films demonstrated antimicrobial activity with films containing ZEO more effective against Escherichia coli and Staphylococcus aureus than those containing MEO. These results suggest that ZEO and MEO have the potential to be directly incorporated into corn starch to prepare antimicrobial biodegradable films for various food packaging applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Mechanical and barrier properties of maize starch-gelatin composite films: effects of amylose content.

    Science.gov (United States)

    Wang, Kun; Wang, Wenhang; Ye, Ran; Xiao, Jingdong; Liu, Yaowei; Ding, Junsheng; Zhang, Shaojing; Liu, Anjun

    2017-08-01

    In order to obtain new reinforcing bio-fillers to improve the physicochemical properties of gelatin-based films, three types of maize starch, waxy maize starch (Ap), normal starch (Ns) and high-amylose starch (Al), were incorporated into gelatin film and the resulting film properties were investigated, focusing on the impact of amylose content. The thickness, opacity and roughness of gelatin film increased depending on the amylose content along with the starch concentration. The effects of the three starches on the mechanical properties of gelatin film were governed by amylose content, starch concentration as well as environmental relative humidity (RH). At 75% RH, the presence of Al and Ns in the gelatin matrix increased the film strength but decreased its elongation, while Ap exhibited an inverse effect. Starch addition decreased the oxygen permeability of the film, with the lowest value at 20% Al and Ns. All starches, notably at 30% content, led to a decrease in the water vapor permeability of the film at 90% RH, especially Ns starch. Furthermore, the starches improved the thermal stability of the film to some extent. Fourier transform infrared spectra indicated that some weak intermolecular interactions such as hydrogen bonding occurred between gelatin and starch. Moreover, a high degree of B-type crystallinity of starch was characterized in Gel-Al film by X-ray diffraction. Tailoring the properties of gelatin film by the incorporation of different types of maize starch provides the potential to extend its applications in edible food packaging. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  17. Preparation of polyvinyl alcohol graphene oxide phosphonate film and research of thermal stability and mechanical properties.

    Science.gov (United States)

    Li, Jihui; Song, Yunna; Ma, Zheng; Li, Ning; Niu, Shuai; Li, Yongshen

    2018-05-01

    In this article, flake graphite, nitric acid, peroxyacetic acid and phosphoric acid are used to prepare graphene oxide phosphonic and phosphinic acids (GOPAs), and GOPAs and polyvinyl alcohol (PVA) are used to synthesize polyvinyl alcohol graphene oxide phosphonate and phosphinate (PVAGOPs) in the case of faint acidity and ultrasound irradiation, and PVAGOPs are used to fabricate PVAGOPs film, and the structure and morphology of GOPAs, PVAGOPs and PVAGOPs film are characterized, and the thermal stability and mechanical properties of PVAGOPs film are investigated. Based on these, it has been proved that GOPAs consist of graphene oxide phosphonic acid and graphene oxide phosphinic acid, and there are CP covalent bonds between them, and PVAGOPs are composed of GOPAs and PVA, and there are six-member lactone rings between GOPAs and PVA, and the thermal stability and mechanical properties of PVAGOPs film are improved effectively. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Characterization of Thin Film Polymers Through Dynamic Mechanical Analysis and Permeation

    Science.gov (United States)

    Herring, Helen

    2003-01-01

    Thin polymer films are being considered, as candidate materials to augment the permeation resistance of cryogenic hydrogen fuel tanks such as would be required for future reusable launch vehicles. To evaluate performance of candidate films after environmental exposure, an experimental study was performed to measure the thermal/mechanical and permeation performance of six, commercial-grade materials. Dynamic storage modulus, as measured by Dynamic Mechanical Analysis, was found over a range of temperatures. Permeability, as measured by helium gas diffusion, was found at room temperature. Test data was correlated with respect to film type and pre-test exposure to moisture, elevated temperature, and cryogenic temperature. Results indicated that the six films were comparable in performance and their resistance to environmental degradation.

  19. Antibacterial, mechanical, and barrier properties of sago starch film incorporated with Betel leaves extract.

    Science.gov (United States)

    Nouri, Leila; Mohammadi Nafchi, Abdorreza

    2014-05-01

    The antimicrobial, mechanical and barrier properties and light transmission of sago starch film incorporated with different percentage of Betel leaf extract (5%, 10%, 20%, and 30%) were evaluated. With regard to mechanical properties, tensile strength decreased when the percentage of extract increased. Elongation at break (%) and seal strength (N/m) increased with increasing percentage of extract from 5% to 20%, while decreased for films containing 30% extract due to heterogeneity of films in this percentage. With regard to barrier properties, water vapour and oxygen barrier properties decreased in all samples when percentage of the extract increased. Antimicrobial activity of all the films increased against both Gram positive and Gram negative bacteria as percentage of Betel leaf extract increased, except for Psuedomonas aeruginosa, which was not susceptible at any percentage of the extract. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Mechanism of sliding friction on a film-terminated fibrillar interface.

    Science.gov (United States)

    Shen, Lulin; Jagota, Anand; Hui, Chung-Yuen

    2009-03-03

    We study the mechanism of sliding friction on a film-terminated fibrillar interface. It has been shown that static friction increases significantly with increasing spacing between fibrils, and with increasing rate of loading. However, surprisingly, the sliding friction remains substantially unaffected both by geometry and by the rate of loading. The presence of the thin terminal film is a controlling factor in determining the sliding friction. Experimentally, and by a simple model in which the indenter is held up by the tension in the thin film, we show how the indenter maintains a nearly constant contact area that is independent of the fibril spacing, resulting in constant sliding friction. By this mechanism, using the film-terminated structure, one can enhance the static friction without affecting the sliding behavior.

  1. Dual mechanical behaviour of hydrogen in stressed silicon nitride thin films

    International Nuclear Information System (INIS)

    Volpi, F.; Braccini, M.; Pasturel, A.; Devos, A.; Raymond, G.; Morin, P.

    2014-01-01

    In the present article, we report a study on the mechanical behaviour displayed by hydrogen atoms and pores in silicon nitride (SiN) films. A simple three-phase model is proposed to relate the physical properties (stiffness, film stress, mass density, etc.) of hydrogenated nanoporous SiN thin films to the volume fractions of hydrogen and pores. This model is then applied to experimental data extracted from films deposited by plasma enhanced chemical vapour deposition, where hydrogen content, stress, and mass densities range widely from 11% to 30%, −2.8 to 1.5 GPa, and 2.0 to 2.8 g/cm 3 , respectively. Starting from the conventional plotting of film's Young's modulus against film porosity, we first propose to correct the conventional calculation of porosity volume fraction with the hydrogen content, thus taking into account both hydrogen mass and concentration. The weight of this hydrogen-correction is found to evolve linearly with hydrogen concentration in tensile films (in accordance with a simple “mass correction” of the film density calculation), but a clear discontinuity is observed toward compressive stresses. Then, the effective volume occupied by hydrogen atoms is calculated taking account of the bond type (N-H or Si-H bonds), thus allowing a precise extraction of the hydrogen volume fraction. These calculations applied to tensile films show that both volume fractions of hydrogen and porosity are similar in magnitude and randomly distributed against Young's modulus. However, the expected linear dependence of the Young's modulus is clearly observed when both volume fractions are added. Finally, we show that the stiffer behaviour of compressive films cannot be only explained on the basis of this (hydrogen + porosity) volume fraction. Indeed this stiffness difference relies on a dual mechanical behaviour displayed by hydrogen atoms against the film stress state: while they participate to the stiffness in compressive films, hydrogen atoms mainly

  2. Mango kernel starch-gum composite films: Physical, mechanical and barrier properties.

    Science.gov (United States)

    Nawab, Anjum; Alam, Feroz; Haq, Muhammad Abdul; Lutfi, Zubala; Hasnain, Abid

    2017-05-01

    Composite films were developed by the casting method using mango kernel starch (MKS) and guar and xanthan gums. The concentration of both gums ranged from 0% to 30% (w/w of starch; db). Mechanical properties, oxygen permeability (OP), water vapor permeability (WVP), solubility in water and color parameters of composite films were evaluated. The crystallinity and homogeneity between the starch and gums were also evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The scanning electron micrographs showed homogeneous matrix, with no signs of phase separation between the components. XRD analysis demonstrated diminished crystalline peak. Regardless of gum type the tensile strength (TS) of composite films increased with increasing gum concentration while reverse trend was noted for elongation at break (EAB) which found to be decreased with increasing gum concentration. The addition of both guar and xanthan gums increased solubility and WVP of the composite films. However, the OP was found to be lower than that of the control with both gums. Furthermore, addition of both gums led to changes in transparency and opacity of MKS films. Films containing 10% (w/w) xanthan gum showed lower values for solubility, WVP and OP, while film containing 20% guar gum showed good mechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Effect of addition of semi refined carrageenan on mechanical characteristics of gum arabic edible film

    Science.gov (United States)

    Setyorini, D.; Nurcahyani, P. R.

    2016-04-01

    Currently the seaweed is processed flour and Semi Refined Carraagenan (SRC). However, total production is small, but both of these products have a high value and are used in a wide variety of products such as cosmetics, processed foods, medicines, and edible film. The aim of this study were (1) to determine the effect of SRC on mechanical characteristics of edible film, (2) to determine the best edible film which added by SRC with different concentration. The edible film added by SRC flour which divided into three concentrations of SRC. There are 1.5%; 3%; and 4.5% of SRC, then added 3% glycerol and 0.6% arabic gum. The mechanical properties of the film measured by a universal testing machine Orientec Co. Ltd., while the water vapor permeability measured by the gravimetric method dessicant modified. The experimental design used was completely randomized design with a further test of Duncan. The result show SRC concentration differences affect the elongation breaking point and tensile strength. But not significant effect on the thickness, yield strength and the modulus of elasticity. The best edible film is edible film with the addition of SRC 4.5%.

  4. Mechanical properties of ultra-thin HfO2 films studied by nano scratches tests

    International Nuclear Information System (INIS)

    Fu, Wei-En; Chang, Yong-Qing; Chang, Chia-Wei; Yao, Chih-Kai; Liao, Jiunn-Der

    2013-01-01

    10-nm-thick atomic layer deposited HfO 2 films were characterized in terms of wear resistance and indentation hardness to investigate the thermal annealing induced impacts on mechanical properties. The wear resistance of ultra-thin films at low loads was characterized using nano-scratch tests with an atomic force microscope. The depth of the nano-scratches decreases with increasing annealing temperature, indicating that the hardness of the annealed films increases with the annealing temperatures. Surface nanoindentation was also performed to confirm the nanoscratch test results. The hardness variation of the annealed films is due to the generation of HfSi x O y induced by the thermal annealing. X-ray photoelectron spectroscopy measurements proved that the hardness of formed HfSi x O y with increasing annealing temperatures. The existence of HfSi x O y broadens the interface, and causes the increase of the interfacial layer thickness. As a result, the surface hardness increases with the increasing HfSi x O y induced by the thermal annealing. - Highlights: ► Mechanical properties of HfO 2 films were assessed by nano-scratch and indentation. ► Scratch depth of HfO 2 films decreased with the increase of annealing temperatures. ► Nano-hardness of HfO 2 films increased with the increase of annealing temperatures

  5. The mechanism of growth of quartz crystals into fused silica

    Science.gov (United States)

    Fratello, V. J.; Hays, J. F.; Spaepen, F.; Turnbull, D.

    1980-01-01

    It is proposed that the growth of quartz crystals into fused silica is effected by a mechanism involving the breaking of an Si-O bond and its association with an OH group, followed by cooperative motion of the nonbridging oxygen and the hydroxyl group which results in the crystallization of a row of several molecules along a crystalline-amorphous interfacial ledge. This mechanism explains, at least qualitatively, all the results of the earlier experimental study of the dependence of quartz crystal growth upon applied pressure: large negative activation volume; single activation enthalpy below Si-O bond energy; growth velocity constant in time, proportional to the hydroxyl and chlorine content, decreasing with increasing degree of reduction, and enhanced by nonhydrostatic stresses; lower pre-exponential for the synthetic than for the natural silica.

  6. Size- and phase-dependent mechanical properties of ultrathin Si films on polyimide substrates

    International Nuclear Information System (INIS)

    Schlich, Franziska F.; Spolenak, Ralph

    2016-01-01

    Ultrathin Si films in the nanometer range are extensively used for electronic and optoelectronic devices. Their mechanical properties have a high impact on the durability of the devices during lifetime. Here, fragmentation and buckling of 8–103 nm thin amorphous and polycrystalline (poly-) Si films on polyimide substrates have been studied by in situ light microscopy, Raman spectroscopy and resistance measurements. Generally, a smaller film thickness and a compressive residual stress delays the fracture of the film. The fracture strength of poly-Si films is larger compared to that of amorphous Si films while the adhesion to the substrate is better for amorphous Si compared to poly-Si. The onset delamination as a function of film thickness differs for the two phases and is described by two different models. Thin-film models for fracture toughness (amorphous Si: K 1C  = 1.49 ± 0.22, poly-Si: K 1C  = 3.36 ± 1.37) are applied, discussed, and found to be consistent with literature values.

  7. TTF/TCNQ-based thin films and microcrystals. Growth and charge transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Solovyeva, Vita

    2011-05-26

    The thesis adresses several problems related to growth and charge transport phenomena in thin films of TTF-TCNQ and (BEDT-TTF)TCNQ. The following main new problems are addressed: - The influence of thin-film specific factors, such as the substrate material and growth-induced defects, on the Peierls transition temperature in TTF-TCNQ thin films was studied; - finite-size effects in TTF-TCNQ were investigated by considering transport properties in TTF-TCNQ microcrystals. The influence of the size of the crystal on the Peierls transition temperature was studied. In this context a new method of microcontact fabrication was employed to favor the measurements; - an analysis of radiation-induced defects in TTF-TCNQ thin films and microcrystals was performed. It was demonstrated than an electron beam can induce appreciable damage to the sample such that its electronic properties are strongly modified; - a bilayer growth method was established to fabricate (BEDT-TTF)TCNQ from the gas phase. This newly developed bilayer growth method was showed to be suitable for testing (BEDT-TTF)TCNQ charge-transfer phase formation; - the structure of the formed (BEDT-TTF)TCNQ charge-transfer compounds was analyzed by using a wide range of experimental techniques. An overview and the description of the basic physical principles underlying charge-transfer compounds is given in chapter 2. Experimental techniques used for the growth and characterization of thin films and microcrystals are presented in chapter 3. Chapter 4 gives an overview of the physical properties of the studied organic materials. Chapter 5 discussed the experimental study of TTF-TCNQ thin films. he Peierls transition in TTF-TCNQ is a consequence of the quasi-one-dimensional structure of the material and depends on different factors, studied in chapters 5 and 6. In contradistinction to TTF-TTCNQ, the (BEDT-TTF)TCNQ charge-transfer compound crystallizes in several different modifications with different physical properties

  8. Growth and characterizations of GaN micro-rods on graphene films for flexible light emitting diodes

    Directory of Open Access Journals (Sweden)

    Kunook Chung

    2014-09-01

    Full Text Available We report the growth of GaN micro-rods and coaxial quantum-well heterostructures on graphene films, together with structural and optical characterization, for applications in flexible optical devices. Graphene films were grown on Cu foil by means of chemical vapor deposition, and used as the substrates for the growth of the GaN micro-rods, which were subsequently transferred onto SiO2/Si substrates. Highly Si-doped, n-type GaN micro-rods were grown on the graphene films using metal–organic chemical vapor deposition. The growth and vertical alignment of the GaN micro-rods, which is a critical factor for the fabrication of high-performance light-emitting diodes (LEDs, were characterized using electron microscopy and X-ray diffraction. The GaN micro-rods exhibited promising photoluminescence characteristics for optoelectronic device applications, including room-temperature stimulated emission. To fabricate flexible LEDs, InxGa1–xN/GaN multiple quantum wells and a p-type GaN layer were deposited coaxially on the GaN micro-rods, and transferred onto Ag-coated polymer substrates using lift-off. Ti/Au and Ni/Au metal layers were formed to provide electrical contacts to the n-type and p-type GaN regions, respectively. The micro-rod LEDs exhibited intense emission of visible light, even after transfer onto the flexible polymer substrate, and reliable operation was achieved following numerous cycles of mechanical deformation.

  9. Determination of the mechanical, diffractometer and thermal properties of chitosan and hydroxypropyl methylcellulose films (HPMC)

    International Nuclear Information System (INIS)

    Rotta, Jefferson; Minatti, Edson; Barreto, Pedro L.M.

    2009-01-01

    This work examined the mechanical, diffractometry and thermal properties of chitosan-hydroxypropyl methylcellulose (HPMC) films. The solutions of chitosan and hydroxypropyl methylcellulose were mixed at different proportions (100/0; 70/30; 50/50; 30/70 and 0/100) respectively, and 20 m L was casting at Petri dishes to posterior analysis of dried films. The miscibility of polymers has been assessed by X-ray diffraction, differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). It was shown that although weak hydrogen bonding exists between the polymer functional groups, the films are not fully miscible at a dry state. (author)

  10. Mechanism of melting in submonolayer films of nitrogen molecules adsorbed on the basal planes of graphite

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Bruch, Ludwig Walter; Taub, H.

    1995-01-01

    The melting mechanism in submonolayer films of N-2 molecules adsorbed on the basal planes of graphite is studied using molecular-dynamics simulations. The melting is strongly correlated with the formation of vacancies in the films. As the temperature increases, the edges of the submonolayer patch...... become atomically rough and vacancies are first created there. Then there is an onset temperature at which the vacancies penetrate into the patch. At an intermediate region of coverages similar to 0.3-0.8 commensurate layers, there is sufficient free volume for the film to melt at that temperature...

  11. Atomistic simulation of charge effects: From tunable thin film growth to isolation of surface states with spin-orbit coupling

    Science.gov (United States)

    Ming, Wenmei

    This dissertation revitalizes the importance of surface charge effects in semiconductor nanostructures, in particular in the context of thin film growth and exotic electronic structures under delicate spin-orbit coupling. A combination of simulation techniques, including density functional theory calculation, kinetic Monte Carlo method, nonequilibrium Green's function method, and tight binding method, were employed to reveal the underlying physical mechanisms of four topics: (1) Effects of Li doping on H-diffusion in MgH 2 for hydrogen storage. It addresses both the effect of Fermi level tuning by charged dopant and the effect of dopant-defect interaction, and the latter was largely neglected in previous works; (2) Tuning nucleation density of the metal island with charge doping of the graphene substrate. It is the first time that the surface charge doping effect is proposed and studied as an effective approach to tune the kinetics of island nucleation at the early stage of thin film growth; (3) Complete isolation of Rashba surface states on the saturated semiconductor surface. It shows that the naturally saturated semiconductor surface of InSe(0001) with Au single layer film provides a mechanism for the formation of Rashba states with large spin splitting; it opens up an innovative route to obtaining ideal Rashba states without the overwhelming bulk spin-degenerate carriers in spin-dependent transport; (4) Formation of large band gap quantum spin Hall state on Si surface. This study reveals the importance of atomic orbital composition in the formation of a topological insulator, and shows promisingly the possible integration of topological insulator technology into Si-based modern electronic devices.

  12. Chemical vapor deposition polymerization the growth and properties of parylene thin films

    CERN Document Server

    Fortin, Jeffrey B

    2004-01-01

    Chemical Vapor Deposition Polymerization - The Growth and Properties of Parylene Thin Films is intended to be valuable to both users and researchers of parylene thin films. It should be particularly useful for those setting up and characterizing their first research deposition system. It provides a good picture of the deposition process and equipment, as well as information on system-to-system variations that is important to consider when designing a deposition system or making modifications to an existing one. Also included are methods to characterizae a deposition system's pumping properties as well as monitor the deposition process via mass spectrometry. There are many references that will lead the reader to further information on the topic being discussed. This text should serve as a useful reference source and handbook for scientists and engineers interested in depositing high quality parylene thin films.

  13. Method for rapid, controllable growth and thickness, of epitaxial silicon films

    Science.gov (United States)

    Wang, Qi [Littleton, CO; Stradins, Paul [Golden, CO; Teplin, Charles [Boulder, CO; Branz, Howard M [Boulder, CO

    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.

  14. Amorphous-tetrahedral diamondlike carbon layered structures resulting from film growth energetics

    Science.gov (United States)

    Siegal, M. P.; Barbour, J. C.; Provencio, P. N.; Tallant, D. R.; Friedmann, T. A.

    1998-08-01

    High-resolution transmission electron microscopy (HRTEM) shows that amorphous-tetrahedral diamondlike carbon (a-tC) films grown by pulsed-laser deposition on Si(100) consist of three-to-four layers, depending on the growth energetics. We estimate the density of each layer using both HRTEM image contrast and Rutherford backscattering spectrometry. The first carbon layer and final surface layer have relatively low density. The bulk of the film between these two layers has higher density. For films grown under the most energetic conditions, there exists a superdense a-tC layer between the interface and bulk layers. The density of all four layers, and the thickness of the surface and interfacial layers, correlate well with the energetics of the depositing carbon species.

  15. Nucleation and Growth of Crystalline Grains in RF-Sputtered TiO2 Films

    Directory of Open Access Journals (Sweden)

    J. C. Johnson

    2009-01-01

    Full Text Available Amorphous TiO2 thin films were radio frequency sputtered onto siliconmonoxide and carbon support films on molybdenum transmission electron microscope (TEM grids and observed during in situ annealing in a TEM heating stage at 250∘C. The evolution of crystallization is consistent with a classical model of homogeneous nucleation and isotropic grain growth. The two-dimensional grain morphology of the TEM foil allowed straightforward recognition of amorphous and crystallized regions of the films, for measurement of crystalline volume fraction and grain number density. By assuming that the kinetic parameters remain constant beyond the onset of crystallization, the final average grain size was computed, using an analytical extrapolation to the fully crystallized state. Electron diffraction reveals a predominance of the anatase crystallographic phase.

  16. Growth Mechanism of Gold Nanorods in Binary Surfactant System

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bo-Mi; Seo, Sun-Hwa; Joe, Ara; Shim, Kyu-Dong; Jang, Eue-Soon [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

    2016-06-15

    In order to reveal the growth mechanism of gold nanorods (GNRs) in a binary surfactant system, we synthesized various GNRs by changing the concentration of the surfactants, AgNO{sub 3}, and HBr in the growth solution. We found that the benzyldime thylhexadecylammoniumchloride surfactant had weak interaction with the gold ions, but it could reduce the membrane fluidity. In addition, we could dramatically decrease the cetyltrimethylammonium bromide concentration required for GNR growth by adding an HBr solution. Notably, Ag{sup +} ions were necessary to break the symmetry of the seed crystals for GNR growth, but increasing the concentration of Ag{sup +} and Br{sup -} ions caused a decrease in the template size.

  17. Growth mechanism and magnon excitation in NiO nanowalls

    Directory of Open Access Journals (Sweden)

    Yang Chun

    2011-01-01

    Full Text Available Abstract The nanosized effects of short-range multimagnon excitation behavior and short-circuit diffusion in NiO nanowalls synthesized using the Ni grid thermal treatment method were observed. The energy dispersive spectroscopy mapping technique was used to characterize the growth mechanism, and confocal Raman scattering was used to probe the antiferromagnetic exchange energy J 2 between next-nearest-neighboring Ni ions in NiO nanowalls at various growth temperatures below the Neel temperature. This study shows that short spin correlation leads to an exponential dependence of the growth temperatures and the existence of nickel vacancies during the magnon excitation. Four-magnon configurations were determined from the scattering factor, revealing a lowest state and monotonic change with the growth temperature. PACS: 75.47.Lx; 61.82.Rx; 75.50.Tt; 74.25.nd; 72.10.Di

  18. Plant growth-promoting bacteria: mechanisms and applications.

    Science.gov (United States)

    Glick, Bernard R

    2012-01-01

    The worldwide increases in both environmental damage and human population pressure have the unfortunate consequence that global food production may soon become insufficient to feed all of the world's people. It is therefore essential that agricultural productivity be significantly increased within the next few decades. To this end, agricultural practice is moving toward a more sustainable and environmentally friendly approach. This includes both the increasing use of transgenic plants and plant growth-promoting bacteria as a part of mainstream agricultural practice. Here, a number of the mechanisms utilized by plant growth-promoting bacteria are discussed and considered. It is envisioned that in the not too distant future, plant growth-promoting bacteria (PGPB) will begin to replace the use of chemicals in agriculture, horticulture, silviculture, and environmental cleanup strategies. While there may not be one simple strategy that can effectively promote the growth of all plants under all conditions, some of the strategies that are discussed already show great promise.

  19. Tailoring the Electrochemical and Mechanical Properties of PEDOT:PSS Films for Bioelectronics

    KAUST Repository

    Elmahmoudy, Mohammed

    2017-02-21

    The effect of 3-glycidoxypropyltrimethoxysilane (GOPS) content in poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) dispersions on the properties of films spun cast from these formulations is investigated. It has been found out that the concentration of GOPS has a tremendous, yet gradual impact on the electrical, electrochemical, and mechanical properties of the PEDOT:PSS/GOPS films and that there is an optimum concentration which maximizes a particular feature of the film such as its water uptake or elasticity. The benefits of aqueous stability and mechanical strength with GOPS are to be compensated by an increase in the electrochemical impedance. GOPS aids obtaining excellent mechanical integrity in aqueous media with still highly conducting properties. Moreover, active devices like organic electrochemical transistors that contain 1 wt% GOPS, which is a concentration that leads to film with high electrical conductivity with sufficient mechanical stability and softness, exhibit steady performance over three weeks. These results suggest that variations in the concentration of such an additive like GOPS can enable a facile co-optimization of electrical and mechanical properties of a conducting polymer film for in vivo bioelectronics application.

  20. Growth, Optical Absorption, and Photoresponse of Copper Oxide Thin Films and Nanocavities

    Science.gov (United States)

    Parry, James P.

    Copper oxide, Cu2O, is one of the most studied semiconductors having been used in devices dating back to the 1920's. The material received additional study recently as an absorbing material in solar cells and hydrogen evolution reactions. The thickness of Cu2O in those devices is often hundreds of nanometers to over one micron thick. This work studies the use of thin film interference to enhance the optical absorption and photoresponse in very thin Cu2O films. The first section focuses on the growth of single phase Cu2O by reactive sputtering. The impact of synthesis parameters including sputtering rate, substrate temperature, oxygen flow, and post-growth annealing on deposited copper oxide films were studied. Other copper oxide phases, Cu4O 3 and CuO were evident when oxygen was added to the post-deposition annealing chamber atmosphere. Very thin Cu2O films were deposited on sputtered Al films by reactively sputtering Cu with DC power at 50W, Ar/O 2 flow 30/16 sccm, substrate deposition temperature at 150°C, followed by vacuum annealing at 350°C. Thin film interference in Cu2O grown on Al films was observed to highly enhance the absorption of films below 100nm thickness. 70nm of Cu 2O on Al absorbed 96% of incident light at 548nm. The absorption resonance wavelength increased with increasing copper oxide thickness, demonstrating the tunability of the resonance maximum. Thin layers of Al2O 3, 15nm or less, between the Al and Cu2O films modified the total absorption but not in a coherent manner. The optical absorption of nanocavities consisting of Al/Al2O 3 50nm/Cu2O were synthesized, optical absorption and photoresponse measured. The photoresponse of the synthesized nanocavities to light from a solar simulator was enhanced for short and long time scales, 1-3 minutes and several hours respectively. The photocurrent of 60nm Cu2O nanocavities doubled during a 2.5hr light soak, which was not enough to saturate the photoconductivity. Persistent photoconductivity

  1. Influence of growth morphology on the Neel temperature of CrRu thin films and heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Prinsloo, A.R.E., E-mail: alettap@uj.ac.z [Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg 2006 (South Africa); Derrett, H.A. [Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg 2006 (South Africa); Hellwig, O. [San Jose Research Center, Hitachi Global Storage Technologies, 3403 Yerba Buena Road, San Jose, CA 95135 (United States); Fullerton, E.E. [University of California, San Diego, La Jolla, CA (United States); Alberts, H.L. [Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg 2006 (South Africa); Berg, N. van den [Department of Physics, University of Pretoria, Lynwood road, Pretoria (South Africa)

    2010-05-15

    Dimensionality effects on epitaxial and polycrystalline Cr{sub 1-x}Ru{sub x} alloy thin films and in Cr/Cr-Ru heterostructures are reported. X-ray analysis on Cr{sub 0.9965}Ru{sub 0.0035} epitaxial films indicates an increase in the coherence length in growth directions (1 0 0) and (1 1 0) with increasing thickness (d), in the range 20<=d<=300 nm. Atomic force microscopy studies on these films shows pronounced vertical growth for d>50 nm, resulting in the formation of columnar structures. The Neel temperatures (T{sub N}) of the Cr{sub 0.9965}Ru{sub 0.0035} films show anomalous behaviour as a function of d at thickness dapprox50 nm. It is interesting to note that this thickness corresponds to that for which a change in film morphology occurs. Experiments on epitaxial Cr{sub 1-x}Ru{sub x} thin films, with 0<=x<=0.013 and d=50 nm, give T{sub N}-x curves that correspond well with that of bulk Cr{sub 1-x}Ru{sub x} alloys. Studies on Cr/Cr{sub 0.9965}Ru{sub 0.0035} superlattices prepared on MgO(1 0 0), with the Cr layer thickness varied between 10 and 50 nm, keeping the Cr{sub 0.9965}Ru{sub 0.0035} thickness constant at 10 nm, indicate a sharp decrease in T{sub N} as the Cr separation layers reaches a thickness of 30 nm; ascribed to spin density wave pinning in the Cr layers for d<30 nm by the adjacent CrRu layers.

  2. Chromium-modified a-C films with advanced structural, mechanical and corrosive-resistant characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Miao Yi [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Jiang, Xiaohong, E-mail: jxh0668@sina.com [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Piliptsou, D.G., E-mail: pdg_@mail.ru [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Zhuang, Yuzhao; Rogachev, A.V.; Rudenkov, A.S. [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Balmakou, A. [Faculty of Material Science and Technology, Slovak University of Technology, Trnava 91724 (Slovakia)

    2016-08-30

    Highlights: • Influence of the chromium interlayer on the structure and mechanical properties of a-C:Cr films. • Residual stress and wear of a-C:Cr and Cr/a-C varies due to their phase and surface morphology. • Chromium-modified a-C films with advanced structural, mechanical and corrosive-resistant characteristics. - Abstract: To improve structural, mechanical and chemical properties of diamond-like carbon films, we developed amorphous carbon chromium-modified composite films fabricated by means of cathode magnetic filtered arc deposition. The properties were analyzed by Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy for the purpose of the structure characterization, elemental analysis and topology examination. Moreover, we also assessed residual stress, the coefficient of friction, hardness, the elastic modulus and corrosion parameters through X-ray double-crystal surface profilometry, tribo-testing, nanoindenter-testing, as well as contact angle measurements and potentiodynamic polarization analysis. As a result of a comparative analysis, we revealed a substantial improvement in the characteristics of developed composite films in comparison with amorphous carbon films. For example, Cr-modification is resulted, in greater integrated performance, toughness and corrosion resistance; the residual stress was reduced substantially.

  3. Mechanical and physical properties of recombinant spider silk films using organic and aqueous solvents.

    Science.gov (United States)

    Tucker, Chauncey L; Jones, Justin A; Bringhurst, Heidi N; Copeland, Cameron G; Addison, J Bennett; Weber, Warner S; Mou, Qiushi; Yarger, Jeffery L; Lewis, Randolph V

    2014-08-11

    Spider silk has exceptional mechanical and biocompatibility properties. The goal of this study was optimization of the mechanical properties of synthetic spider silk thin films made from synthetic forms of MaSp1 and MaSp2, which compose the dragline silk of Nephila clavipes. We increased the mechanical stress of MaSp1 and 2 films solubilized in both HFIP and water by adding glutaraldehyde and then stretching them in an alcohol based stretch bath. This resulted in stresses as high as 206 MPa and elongations up to 35%, which is 4× higher than the as-poured controls. Films were analyzed using NMR, XRD, and Raman, which showed that the secondary structure after solubilization and film formation in as-poured films is mainly a helical conformation. After the post-pour stretch in a methanol/water bath, the MaSp proteins in both the HFIP and water-based films formed aligned β-sheets similar to those in spider silk fibers.

  4. Vanadium and molybdenum oxide thin films on Au(111). Growth and surface characterization

    Energy Technology Data Exchange (ETDEWEB)

    Guimond, Sebastien

    2009-06-04

    The growth and the surface structure of well-ordered V{sub 2}O{sub 3}, V{sub 2}O{sub 5} and MoO{sub 3} thin films have been investigated in this work. These films are seen as model systems for the study of elementary reaction steps occurring on vanadia and molybdena-based selective oxidation catalysts. It is shown that well-ordered V{sub 2}O{sub 3}(0001) thin films can be prepared on Au(111). The films are terminated by vanadyl groups which are not part of the V{sub 2}O{sub 3} bulk structure. Electron irradiation specifically removes the oxygen atoms of the vanadyl groups, resulting in a V-terminated surface. The fraction of removed vanadyl groups is controlled by the electron dose. Such surfaces constitute interesting models to probe the relative role of both the vanadyl groups and the undercoordinated V ions at the surface of vanadia catalysts. The growth of well-ordered V{sub 2}O{sub 5}(001) and MoO{sub 3}(010) thin films containing few point defects is reported here for the first time. These films were grown on Au(111) by oxidation under 50 mbar O{sub 2} in a dedicated high pressure cell. Contrary to some of the results found in the literature, the films are not easily reduced by annealing in UHV. This evidences the contribution of radiation and surface contamination in some of the reported thermal reduction experiments. The growth of ultrathin V{sub 2}O{sub 5} and MoO{sub 3} layers on Au(111) results in formation of interface-specific monolayer structures. These layers are coincidence lattices and they do not correspond to any known oxide bulk structure. They are assumed to be stabilized by electronic interaction with Au(111). Their formation illustrates the polymorphic character and the ease of coordination units rearrangement which are characteristic of both oxides. The formation of a second layer apparently precedes the growth of bulk-like crystallites for both oxides. This observation is at odds with a common assumption that crystals nucleate as soon as a

  5. Anisotropic Growth of Otavite on Calcite: Implications for Heteroepitaxial Growth Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Riechers, Shawn L. [Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Kerisit, Sebastien N. [Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States

    2017-12-18

    Elucidating how cation intermixing can affect the mechanisms of heteroepitaxial growth in aqueous media has remained a challenging endeavor. Toward this goal, in situ atomic force microscopy was employed to image the heteroepitaxial growth of otavite (CdCO3) at the (10-14) surface of calcite (CaCO3) single crystals in static aqueous conditions. Heteroepitaxial growth proceeded via spreading of three-dimensional (3D) islands and two-dimensional (2D) atomic layers at low and high initial saturation levels, respectively. Experiments were carried out as a function of applied force and imaging mode thus enabling determination of growth mechanisms unaltered by imaging artifacts. This approach revealed the significant anisotropic nature of heteroepitaxial growth on calcite in both growth modes and its dependence on supersaturation, intermixing, and substrate topography. The 3D islands not only grew preferentially along the [42-1] direction relative to the [010] direction, resulting in rod-like surface precipitates, but also showed clear preference for growth from the island end rich in obtuse/obtuse kink sites. Pinning to step edges was observed to often reverse this tendency. In the 2D growth mode, the relative velocities of acute and obtuse steps were observed to switch between the first and second atomic layers. This phenomenon stemmed from the significant Cd-Ca intermixing in the first layer, despite bulk thermodynamics predicting the formation of almost pure otavite. Composition effects were also responsible for the inability of 3D islands to grow on 2D layers in cases where both modes were observed to occur simultaneously. Overall, the AFM images highlighted the effects of intermixing on heteroepitaxial growth, particularly how it can induce thickness-dependent growth mechanisms at the nanoscale.

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

    Directory of Open Access Journals (Sweden)

    Giovanni A. Badini Confalonieri

    2010-12-01

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

  7. Growth and optical characteristics of high-quality ZnO thin films on graphene layers

    Directory of Open Access Journals (Sweden)

    Suk In Park

    2015-01-01

    Full Text Available We report the growth of high-quality, smooth, and flat ZnO thin films on graphene layers and their photoluminescence (PL characteristics. For the growth of high-quality ZnO thin films on graphene layers, ZnO nanowalls were grown using metal-organic vapor-phase epitaxy on oxygen-plasma treated graphene layers as an intermediate layer. PL measurements were conducted at low temperatures to examine strong near-band-edge emission peaks. The full-width-at-half-maximum value of the dominant PL emission peak was as narrow as 4 meV at T = 11 K, comparable to that of the best-quality films reported previously. Furthermore, the stimulated emission of ZnO thin films on the graphene layers was observed at the low excitation energy of 180 kW/cm2 at room temperature. Their structural and optical characteristics were investigated using X-ray diffraction, transmission electron microscopy, and PL spectroscopy.

  8. Epitaxial growth of Bi ultra-thin films on GaAs by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Plaza, M. [Dpto. Fisica de Materiales, Universidad Complutense de Madrid, 28040 Madrid (Spain); Abuin, M. [Dpto. Fisica de Materiales, Universidad Complutense de Madrid, 28040 Madrid (Spain); Unidad Asociada IQFR(CSIC)-UCM, Madrid 28040 (Spain); Mascaraque, A., E-mail: arantzazu.mascaraque@fis.ucm.es [Dpto. Fisica de Materiales, Universidad Complutense de Madrid, 28040 Madrid (Spain); Unidad Asociada IQFR(CSIC)-UCM, Madrid 28040 (Spain); Gonzalez-Barrio, M.A. [Dpto. Fisica de Materiales, Universidad Complutense de Madrid, 28040 Madrid (Spain); Unidad Asociada IQFR(CSIC)-UCM, Madrid 28040 (Spain); Perez, L. [Dpto. Fisica de Materiales, Universidad Complutense de Madrid, 28040 Madrid (Spain); Instituto de Sistemas Optoelectronicos y Microtecnologia, Universidad Politecnica de Madrid, 28040 Madrid (Spain)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Electrodeposition of Bi films on GaAs substrates with different orientations. Black-Right-Pointing-Pointer Ultra thin films - 50 nm - are continuous and smooth. Black-Right-Pointing-Pointer Bi always grows with (0 1 L) orientations. Black-Right-Pointing-Pointer Epitaxial growth onto As terminated surfaces. Black-Right-Pointing-Pointer Proposed model based on structural and chemical considerations. - Abstract: We report on the growth of thin bismuth films on GaAs substrates with different orientations by means of electrochemical deposition. Atomic force microscopy reveals that the films are continuous and exhibit low roughness when they are grown under the appropriate overpotential. {omega}-2{theta} X-ray diffraction scans only show reflections that can be indexed as (0 1 L), meaning that Bi grows onto GaAs only in combinations of the (0 0 1) and (0 1 0) orientations. The matching between the GaAs substrate and the Bi layer has been studied by asymmetric X-ray scans, finding that Bi grows epitaxially on GaAs(1 1 0) and GaAs(1 1 1)B, both As-terminated surfaces. We explain these results by structural and chemical considerations.

  9. Epitaxial growth of highly-crystalline spinel ferrite thin films on perovskite substrates for all-oxide devices.

    Science.gov (United States)

    Moyer, Jarrett A; Gao, Ran; Schiffer, Peter; Martin, Lane W

    2015-06-01

    The potential growth modes for epitaxial growth of Fe3O4 on SrTiO3 (001) are investigated through control of the energetics of the pulsed-laser deposition growth process (via substrate temperature and laser fluence). We find that Fe3O4 grows epitaxially in three distinct growth modes: 2D-like, island, and 3D-to-2D, the last of which is characterized by films that begin growth in an island growth mode before progressing to a 2D growth mode. Films grown in the 2D-like and 3D-to-2D growth modes are atomically flat and partially strained, while films grown in the island growth mode are terminated in islands and fully relaxed. We find that the optimal structural, transport, and magnetic properties are obtained for films grown on the 2D-like/3D-to-2D growth regime boundary. The viability for including such thin films in perovskite-based all-oxide devices is demonstrated by growing a Fe3O4/La0.7Sr0.3MnO3 spin valve epitaxially on SrTiO3.

  10. Role of the substrate on the growth of Ni-Ti sputtered thin films

    Energy Technology Data Exchange (ETDEWEB)

    Martins, R.M.S. [Forschungszentrum Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany)], E-mail: rui.martins@esrf.fr; Schell, N.; Beckers, M. [Forschungszentrum Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Silva, R.J.C.; Mahesh, K.K.; Fernandes, F.M. Braz [CENIMAT, Campus da FCT/UNL, 2829-516 Monte de Caparica (Portugal)

    2008-05-25

    Ni-Ti thin films have been recognized as promising and high performance materials in the field of microelectromechanical system applications. However, important issues like formation of film texture and its control are still unresolved. Widening the scope of previous experiments concerning the influence of the deposition parameters on the Ni-Ti films structure, here we show how different crystallographic orientations can be obtained by changing the substrate type. The growth of near-equiatomic Ni-Ti films, deposited by magnetron co-sputtering from Ni-Ti and Ti targets on heated substrates ({approx}470 deg. C), has been studied in situ by X-ray diffraction at a synchrotron radiation beamline. As mentioned in other studies for depositions on Si{sub 100}, a 1 1 0 fiber texture is observed for the B2 phase. However, a preferential stacking of 1 0 0 planes of the B2 phase parallel to the film surface was observed when using a MgO{sub 100} substrate. The preferential orientation of B2{sub 100}||MgO{sub 100} was very strong and was kept as such until the end of the deposition, which lasted for 7.2 ks ({approx}900 nm). Ni-Ti films were also deposited on a TiN layer ({approx}15 nm) previously deposited on top of a SiO{sub 2}/Si{sub 100} substrate. In this case, a crossover from 1 1 0 oriented grains dominating at small thicknesses, to 2 1 1 oriented grains taking over at larger thicknesses was observed. These are promising results concerning the manipulation of the crystallographic orientations of Ni-Ti thin films, since the texture has a strong influence on the extent of the strain recovery.

  11. Thickness-controlled direct growth of nanographene and nanographite film on non-catalytic substrates.

    Science.gov (United States)

    Du, Lei; Yang, Liu; Hu, Zhiting; Zhang, Jiazhen; Huang, Chunlai; Sun, Liaoxin; Wang, Lin; Wei, Dacheng; Gang, Chen; Lu, Wei

    2018-03-07

    Metal-catalysed chemical vapor deposition has been broadly employed for large-scale production of high-quality graphene. However, a following transfer process to targeted substrates is needed, which is incompatible with current silicon technology. We here report a new chemical vapor deposition approach to form nanographene and nanographite films with accurate thickness control directly on non-catalytic substrates such as silicon dioxide and quartz at 800℃. The growth time is as short as a few seconds. The approach includes using 9-bis(diethylamino)silylanthracene as the carbon source and an atomic layer deposition controlling system. The structure of the formed nanographene and nanographite films were characterized using atomic force microscopy, high resolution transmission electron microscopy, Raman scattering, and X-ray photoemission spectroscopy. The nanographite film exhibits a transmittance higher than 80% at 550 nm and a sheet electrical resistance of 2000 ohms per square at room temperature. A negative temperature-dependence of the resistance of the nanographite film is also observed. Moreover, the thickness of the films can be precisely controlled via the deposition cycles using an atomic layer deposition system, which promotes great application potential for optoelectronic and thermoelectronic-devices. © 2018 IOP Publishing Ltd.

  12. The growth and evolution of thin oxide films on delta-plutonium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Flores, Harry G [Los Alamos National Laboratory; Pugmire, David L [Los Alamos National Laboratory

    2009-01-01

    The common oxides of plutonium are the dioxide (PuO{sub 2}) and the sesquioxide (Pu{sub 2}O{sub 3}). The structure of an oxide on plutonium metal under air at room temperature is typically described as a thick PuO{sub 2} film at the gas-oxide interface with a thinner PuO{sub 2} film near the oxide-metal substrate interface. In a reducing environment, such as ultra high vacuum, the dioxide (Pu{sup 4+}; O/Pu = 2.0) readily converts to the sesquioxide (Pu{sup 3+}; O/Pu = 1.5) with time. In this work, the growth and evolution of thin plutonium oxide films is studied with x-ray photoelectron spectroscopy (XPS) under varying conditions. The results indicate that, like the dioxide, the sesquioxide is not stable on a very clean metal substrate under reducing conditions, resulting in substoichiometric films (Pu{sub 2}O{sub 3-y}). The Pu{sub 2}O{sub 3-y} films prepared exhibit a variety of stoichiometries (y = 0.2-1) as a function of preparation conditions, highlighting the fact that caution must be exercised when studying plutonium oxide surfaces under these conditions and interpreting resulting data.

  13. Thickness-controlled direct growth of nanographene and nanographite film on non-catalytic substrates

    Science.gov (United States)

    Du, Lei; Yang, Liu; Hu, Zhiting; Zhang, Jiazhen; Huang, Chunlai; Sun, Liaoxin; Wang, Lin; Wei, Dacheng; Chen, Gang; Lu, Wei

    2018-05-01

    Metal-catalyzed chemical vapor deposition (CVD) has been broadly employed for large-scale production of high-quality graphene. However, a following transfer process to targeted substrates is needed, which is incompatible with current silicon technology. We here report a new CVD approach to form nanographene and nanographite films with accurate thickness control directly on non-catalytic substrates such as silicon dioxide and quartz at 800 °C. The growth time is as short as a few seconds. The approach includes using 9-bis(diethylamino)silylanthracene as the carbon source and an atomic layer deposition (ALD) controlling system. The structure of the formed nanographene and nanographite films were characterized using atomic force microscopy, high resolution transmission electron microscopy, Raman scattering, and x-ray photoemission spectroscopy. The nanographite film exhibits a transmittance higher than 80% at 550 nm and a sheet electrical resistance of 2000 ohms per square at room temperature. A negative temperature-dependence of the resistance of the nanographite film is also observed. Moreover, the thickness of the films can be precisely controlled via the deposition cycles using an ALD system, which promotes great application potential for optoelectronic and thermoelectronic-devices.

  14. Growth and Switching of Ferroelectric Nanocrystals from Ultrathin Film of Copolymer of Vinylidene Fluoride and Trifluoroethylene

    Directory of Open Access Journals (Sweden)

    R. Gaynutdinov

    2011-01-01

    Full Text Available The ferroelectric nanocrystals of the copolymer of vinylidene fluoride and trifluoroethylene P(VDF-TrFE were grown from ultrathin Langmuir-Blodgett (LB films on Si substrate. The annealing of ultrathin LB films with thickness of 3 monolayers (5 nm in air in paraelectric phase at temperature 125∘C was performed. The self-assembly leads to the growth of nanocrystals of ferroelectric copolymer 15–25 nm thick and 100–200 nm in diameter. The nanocrystals presumably belong to orthorhombic space group, where axis 2 is the direction of spontaneous polarization (and normal to substrate. By means of atomic force microscopy (AFM, the kinetics of ferroelectric nanocrystals growth and their switching were investigated. The obtained results confirm the conclusions that copolymer nanocrystals are candidates for high-density nonvolatile storage media devices.

  15. Underpotential deposition-mediated layer-by-layer growth of thin films

    Science.gov (United States)

    Wang, Jia Xu; Adzic, Radoslav R.

    2015-05-19

    A method of depositing contiguous, conformal submonolayer-to-multilayer thin films with atomic-level control is described. The process involves the use of underpotential deposition of a first element to mediate the growth of a second material by overpotential deposition. Deposition occurs between a potential positive to the bulk deposition potential for the mediating element where a full monolayer of mediating element forms, and a potential which is less than, or only slightly greater than, the bulk deposition potential of the material to be deposited. By cycling the applied voltage between the bulk deposition potential for the mediating element and the material to be deposited, repeated desorption/adsorption of the mediating element during each potential cycle can be used to precisely control film growth on a layer-by-layer basis. This process is especially suitable for the formation of a catalytically active layer on core-shell particles for use in energy conversion devices such as fuel cells.

  16. Tribology. Mechanisms of antiwear tribofilm growth revealed in situ by single-asperity sliding contacts.

    Science.gov (United States)

    Gosvami, N N; Bares, J A; Mangolini, F; Konicek, A R; Yablon, D G; Carpick, R W

    2015-04-03

    Zinc dialkyldithiophosphates (ZDDPs) form antiwear tribofilms at sliding interfaces and are widely used as additives in automotive lubricants. The mechanisms governing the tribofilm growth are not well understood, which limits the development of replacements that offer better performance and are less likely to degrade automobile catalytic converters over time. Using atomic force microscopy in ZDDP-containing lubricant base stock at elevated temperatures, we monitored the growth and properties of the tribofilms in situ in well-defined single-asperity sliding nanocontacts. Surface-based nucleation, growth, and thickness saturation of patchy tribofilms were observed. The growth rate increased exponentially with either applied compressive stress or temperature, consistent with a thermally activated, stress-assisted reaction rate model. Although some models rely on the presence of iron to catalyze tribofilm growth, the films grew regardless of the presence of iron on either the tip or substrate, highlighting the critical role of stress and thermal activation. Copyright © 2015, American Association for the Advancement of Science.

  17. Room temperature growth of biaxially aligned yttria-stabilized zirconia films on glass substrates by pulsed-laser deposition

    CERN Document Server

    Li Peng; Mazumder, J

    2003-01-01

    Room temperature deposition of biaxially textured yttria-stabilized zirconia (YSZ) films on amorphous glass substrates was successfully achieved by conventional pulsed-laser deposition. The influence of the surrounding gases, their pressure and the deposition time on the structure of the films was studied. A columnar growth process was revealed based on the experimental results. The grown biaxial texture appears as a kind of substrate independence, which makes it possible to fabricate in-plane aligned YSZ films on various substrates.

  18. Fibrous tissues growth and remodeling: Evolutionary micro-mechanical theory

    Science.gov (United States)

    Lanir, Yoram

    2017-10-01

    Living fibrous tissues are composite materials having the unique ability to adapt their size, shape, structure and mechanical properties in response to external loading. This adaptation, termed growth and remodeling (G&R), occurs throughout life and is achieved via cell-induced turnover of tissue constituents where some are degraded and new ones are produced. Realistic mathematical modeling of G&R provides insight into the basic processes, allows for hypotheses testing, and constitutes an essential tool for establishing clinical thresholds of pathological remodeling and for the production of tissue substitutes aimed to achieve target structure and properties. In this study, a general 3D micro-mechanical multi-scale theory of G&R in fibrous tissue was developed which connects between the evolution of the tissue structure and properties, and the underlying mechano-biological turnover events of its constituents. This structural approach circumvents a fundamental obstacle in modeling growth mechanics since the growth motion is not bijective. The model was realized for a flat tissue under two biaxial external loadings using data-based parameter values. The predictions show close similarity to characteristics of remodeled adult tissue including its structure, anisotropic and non-linear mechanical properties, and the onset of in situ pre-strain and pre-stress. The results suggest that these important features of living fibrous tissues evolve as they grow.

  19. Growth and Characterisation of Pulsed-Laser Deposited Tin Thin Films on Cube-Textured Copper at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Szwachta G.

    2016-06-01

    Full Text Available High-quality titanium nitride thin films have been grown on a cube-textured copper surface via pulsed laser deposition. The growth of TiN thin films has been very sensitive to pre-treatment procedure and substrate temperature. It is difficult to grow heteroexpitaxial TiN films directly on copper tape due to large differences in lattice constants, thermal expansion coefficients of the two materials as well as polycrystalline structure of substrate. The X-Ray diffraction measurement revealed presence of high peaks belonged to TiN(200 and TiN(111 thin films, depending on used etcher of copper surface. The electron diffraction patterns of TiN(200/Cu films confirmed the single-crystal nature of the films with cube-on-cube epitaxy. The high-resolution microscopy on our films revealed sharp interfaces between copper and titanium nitride with no presence of interfacial reaction.

  20. Preferential orientation growth of ITO thin film on quartz substrate with ZnO buffer layer by magnetron sputtering technique

    Science.gov (United States)

    Du, Wenhan; Yang, Jingjing; Xiong, Chao; Zhao, Yu; Zhu, Xifang

    2017-07-01

    In order to improve the photoelectric transformation efficiency of thin-film solar cells, one plausible method was to improve the transparent conductive oxides (TCO) material property. In-doped tin oxide (ITO) was an important TCO material which was used as a front contact layer in thin-film solar cell. Using magnetron sputtering deposition technique, we prepared preferential orientation ITO thin films on quartz substrate. XRD and SEM measurements were used to characterize the crystalline structure and morphology of ITO thin films. The key step was adding a ZnO thin film buffer layer before ITO deposition. ZnO thin film buffer layer increases the nucleation center numbers and results in the (222) preferential orientation growth of ITO thin films.

  1. Resolving nanoparticle growth mechanisms from size- and time-dependent growth rate analysis

    Science.gov (United States)

    Pichelstorfer, Lukas; Stolzenburg, Dominik; Ortega, John; Karl, Thomas; Kokkola, Harri; Laakso, Anton; Lehtinen, Kari E. J.; Smith, James N.; McMurry, Peter H.; Winkler, Paul M.

    2018-01-01

    Atmospheric new particle formation occurs frequently in the global atmosphere and may play a crucial role in climate by affecting cloud properties. The relevance of newly formed nanoparticles depends largely on the dynamics governing their initial formation and growth to sizes where they become important for cloud microphysics. One key to the proper understanding of nanoparticle effects on climate is therefore hidden in the growth mechanisms. In this study we have developed and successfully tested two independent methods based on the aerosol general dynamics equation, allowing detailed retrieval of time- and size-dependent nanoparticle growth rates. Both methods were used to analyze particle formation from two different biogenic precursor vapors in controlled chamber experiments. Our results suggest that growth rates below 10 nm show much more variation than is currently thought and pin down the decisive size range of growth at around 5 nm where in-depth studies of physical and chemical particle properties are needed.

  2. Growth parameter control toward mobility enchancement in doped BaSnO3 thin films

    Science.gov (United States)

    Singh, Prastuti; Swartz, Adrian; Lu, Di; Nishio, Kazunori; Hikita, Yasuyuki; Hwang, Harold

    Doped BaSnO3 is known to exhibit high electron mobility at room temperature, showing great prospects as an transparent conducting oxide. However, when grown epitaxially on perovskite substrates, thin films exhibit reduced mobilities compared with bulk single crystals due to scattering from the formation of dislocations at the interface of the thin film and substrate. In this emerging field, correlating synthesis growth regimes, structure, and stoichiometry with transport properties is critical for developing next level oxide electronic devices. Here, we will discuss our results linking growth conditions and transport properties of La-doped BaSnO3 (BLSO) to enhance mobility. In addition to varying standard growth parameters, we deposited BLSO on a hygroscopic pseudo-perovskite buffer layer. The pseudo-perovskite buffer acts as a sacrificial layer that can be selectively etched to produce conductive free-standing BLSO membranes, free of the underlying substrate. This allows us to minimize film dislocation density and examine BLSO transport properties in the limit of no substrate.

  3. Cassava starch films containing acetylated starch nanoparticles as reinforcement: Physical and mechanical characterization.

    Science.gov (United States)

    Teodoro, Ana Paula; Mali, Suzana; Romero, Natália; de Carvalho, Gizilene Maria

    2015-08-01

    This paper reports the use of acetylated starch nanoparticles (NPAac) as reinforcement in thermoplastic starch films. NPAac with an average size of approximately 500 nm were obtained by nanoprecipitation. Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) indicated that NPAac are more thermally stable and essentially amorphous when compared with acetylated starch. Thermoplastic starch films with different proportions of NPAac (0.5, 1.0, 1.5, 10.0%, w/w) were obtained and characterized by scanning electron microscopy (SEM), water vapor permeability (WVP), adsorption isotherms, TGA and mechanical tests. The inclusion of reinforcement caused changes in film properties: WVP was lowered by 41% for film with 1.5% (w/w) of NPAac and moisture adsorption by 33% for film with 10% (w/w) of NPAac; and the Young's modulus and thermal stability were increased by 162% and 15%, respectively, for film with 0.5% (w/w) of NPAac compared to the starch film without the addition of NPAac. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Influence of chitosan concentration on mechanical and barrier properties of corn starch/chitosan films.

    Science.gov (United States)

    Ren, Lili; Yan, Xiaoxia; Zhou, Jiang; Tong, Jin; Su, Xingguang

    2017-12-01

    The active packaging films based on corn starch and chitosan were prepared through mixing the starch solution and the chitosan solution (1:1) by casting. The aim of this work was to characterize and analyze the effects of the chitosan concentrations (0, 21, 41, 61 and 81wt% of starch) on physicochemical, mechanical and water vapor barrier properties as well as morphological characteristics of the corn starch/chitosan (CS/CH) films. Starch molecules and chitosan could interact through hydrogen bonding as confirmed from the shift of the main peaks to higher wavenumbers in FTIR and the reduction of crystallinity in XRD. Results showed that the incorporation of chitosan resulted in an increase in film solubility, total color differences, tensile strength and elongation at break and a decrease in Young's modulus and water vapor permeability (WVP). Elongation at break of the CS/CH films increased with increasing of chitosan concentration, and reached a maximum at 41 wt%, then declined at higher chitosan concentration. The WVP of CS/CH films increased with an increase of chitosan concentration and the same tendency observed for the moisture content. The results suggest that this biodegradable CS/CH films could potentially be used as active packaging films for food and pharmaceutical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Growth and thermal oxidation of Ru and ZrO2 thin films as oxidation protective layers

    NARCIS (Netherlands)

    Coloma Ribera, R.

    2017-01-01

    This thesis focuses on the study of physical and chemical processes occurring during growth and thermal oxidation of Ru and ZrO2 thin films. Acting as oxidation resistant capping materials to prevent oxidation of layers underneath, these films have several applications, i.e., in microelectronics

  6. Mechanical, Thermal and Surface Investigations of Chitosan/Agar/PVA Ternary Blended Films

    Directory of Open Access Journals (Sweden)

    Esam A. El-Hefian

    2011-01-01

    Full Text Available The mechanical and thermal properties of chitosan/agar/poly vinyl alcohol (CS/AG/PVA ternary blended films having various proportions considering chitosan as the main component were investigated. The various variables static water contact angle such as contact angle, drop base area, drop volume and drop height was also studied in correlation with the variation of time. Results obtained from mechanical measurements showed a noticeable increase in the tensile strength (TS coincided with a sharp decrease in elongation percent at break (E% of blended films with increasing agar and PVA contents. The DSC results prevailed the development of an interaction between chitosan individual components: agar and PVA. Moreover, an enhancement of the wettability of the blends was obtained with increasing agar and PVA contents. It was also found that the pure CS film and the blended films with 90/05/05 and 80/10/10 compositions were more affected by time than blended films with other compositions when the contact angle, the drop height and the drop length were studied as a function of time. In addition, when the drop is initially placed on the substrate, the drop area and the drop volume of all films remained almost constant up to a certain time after which they showed a slight difference with the elapse of time.

  7. The characterization of protein release from sericin film in the presence of an enzyme: towards fibroblast growth factor-2 delivery.

    Science.gov (United States)

    Nishida, Ayumu; Naganuma, Tsuyoshi; Kanazawa, Takanori; Takashima, Yuuki; Yamada, Masaki; Okada, Hiroaki

    2011-07-29

    Aqueous preparations of silk protein (sericin) films were prepared to evaluate their biodegradation properties. In the absence of trypsin, sericin film swelled rapidly, kept its shape, and remained unaltered for 28 days or longer due to form β-sheet structures. In the presence of trypsin, sericin film gradually degraded; since the rate depended on the concentration of trypsin, the films likely underwent enzymatic hydrolysis. Sericin film incorporating the model protein drug fluorescein isothiocyanate-albumin (FA) also gradually degraded in the presence of trypsin and resulted in the sustained release of FA for 2 weeks or longer; in contrast, FA release was quite slow in the absence of trypsin. It is expected that sericin film has potential as a biodegradable and drug-releasing carrier. To evaluate the practical applicability of sericin film for the repair of defective tissues, fibroblast growth factor-2 (FGF-2) was incorporated into sericin films and the films were implanted on skull defects in rats. Whereas FGF-2 release was suppressed in the absence of trypsin in vitro, it appears that FGF-2, immobilized by ionic interactions between sericin and FGF-2, can be sustained-released in vivo from films incorporating 2500 or 250 ng of FGF-2 to support the growth of tissue around wounds. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Influence of Ni Solute segregation on the intrinsic growth stresses in Cu(Ni) thin films

    International Nuclear Information System (INIS)

    Kaub, T.M.; Felfer, P.; Cairney, J.M.; Thompson, G.B.

    2016-01-01

    Using intrinsic solute segregation in alloys, the compressive stress in a series of Cu(Ni) thin films has been studied. The highest compressive stress was noted in the 5 at.% Ni alloy, with increasing Ni concentration resulting in a subsequent reduction of stress. Atom probe tomography quantified Ni's Gibbsian interfacial excess in the grain boundaries and confirmed that once grain boundary saturation is achieved, the compressive stress was reduced. This letter provides experimental support in elucidating how interfacial segregation of excess adatoms contributes to the post-coalescence compressive stress generation mechanism in thin films. - Graphical abstract: Cu(Ni) film stress relationship with Ni additions. Atom probe characterization confirms solute enrichment in the boundaries, which was linked to stress response.

  9. Sensitizing mechanism and adsorption properties of dye-sensitized TiO sub 2 thin films

    CERN Document Server

    Hu Zhi Xue; Wang Kong Jia

    2002-01-01

    The dye-sensitized TiO sub 2 complex films were prepared by the dye coat onto TiO sub 2 surfaces, and the sensitizing mechanism and adsorption properties of the dye-sensitized TiO sub 2 complex films were investigated. The influence of the application conditions of dye adsorbed on TiO sub 2 films on the amount of dye adsorption was discussed. Experimental results show that the concentration, the temperature of dye solutions and the dipping time of TiO sub 2 films in the dye solutions have a significant influence on the amount of dye adsorption. Cell test indicates that the conversion efficiency of light to electricity increases with the amount of dye adsorption

  10. Ion bombardment during thin film deposition and its influence on mechanical and chemical surface properties

    Science.gov (United States)

    Wolf, G. K.; Ensinger, W.

    1991-07-01

    Directed energy in the form of energetic ion beams is an excellent tool for the modification of thin film and interface properties. The easy control of ion beam parameters causes the high flexibility of the technique. The influence of ion bombardment during deposition of thin films and coatings (IBAD) on their mechanical and chemical behaviour is reviewed in this article. Firstly the controlled production of IBAD films or multilayers with well defined composition is described. Secondly the influence of ion bombardment on selected properties is considered. Adhesion, stress and structure or texture and their dependence on process parameters are discussed. Thirdly the role of adhesion, stress and porosity of films for their use for corrosion and oxidation protection is treated. Finally in the conclusion an attempt is made to define the present status of IBAD techniques compared with other PVD processes.

  11. EFFECT OF PLASTICIZERS ON MECHANICAL PROPERTIES OF EDIBLE FILM FROM JANENG STARCH – CHITOSAN

    Directory of Open Access Journals (Sweden)

    Narlis Juandi

    2016-10-01

    Full Text Available The interest in the development of edible and biodegradable films has increased because it is every day more evident that non degradable are doing much damage to the environment. In this research, edible films were based on blends of janeng starch in different proportions, added of palm oil or glycerol, which were used as plasticizers. The objective was to study the effect of two different plasticizers, palm oil and glycerol of edible film from janeng starch–chitosan on the mechanical properties and FTIR spectra. Increasing concentration of glycerol as plasticizer resulted tend to increased tensile strength and elongation at break. The tensile strength and elongation at break values for palm oil is higher than glycerol as plasticizer at the same concentration. FTIR spectra show the process of making edible film from janeng starch–chitosan with palm oil or glycerol as plasticizers are physically mixing in the presence of hydrogen interactions between chains.

  12. Activation energies of grain growth mechanisms in aluminum coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jankowski, Alan [Lawrence Livermore National Laboratory, Chemistry and Materials Science, CA (United States)]. E-mail: jankowski1@11nl.gov; Ferreira, James [Lawrence Livermore National Laboratory, Chemistry and Materials Science, CA (United States); Hayes, Jeffrey [Lawrence Livermore National Laboratory, Mechanical Engineering, Livermore, CA 94551-9900 (United States)

    2005-11-22

    To produce a specific grain size in metallic coatings requires precise control of the time at temperature during the deposition process. Aluminum coatings are deposited using electron-beam evaporation onto heated substrate surfaces of both mica and lithium flouride. The grain size of the coating is determined upon examination of the microstructure in plan view and cross-section. Ideal grain growth is observed over the entire experimental range of temperature examined from 413 to 843 K. A transition in the activation energy for grain growth from 0.87 to 2.04 eV atom{sup -1} is observed as the temperature increases from < 526 K to > 588 K. The transition is indicative of the dominant mechanism for grain growth shifting with increasing temperature from grain boundary to lattice diffusion.

  13. Mechanics of pressure solution seam growth and evolution

    Science.gov (United States)

    Zhou, Xiaoxian; Aydin, Atilla

    2010-12-01

    Pressure solution seams (PSSs) can be idealized as localized volume reduction structures (LVRSs) in terms of their mechanics. Previous mechanical analyses of LVRSs, including compaction bands, showed that the normal stresses at the tips of LVRSs are compressive and significantly amplified with respect to the remote stresses, whereas on the flanks they are slightly reduced. These results can be used to rationalize the in-plane growth of PSSs for a certain distance, however, based on these stress conditions alone, it is not possible to explain the widening and transverse coalescence of PSSs. In this study, based on laboratory and field observations that the PSS surfaces are extremely rough, we introduced asperities with triangular, semicircular, and rectangular geometries on the flanks of the LVRSs into our mechanical model to see if these asperities can raise stresses in these locations, which may rationalize the transverse growth of PSSs. It is found that these asperities can produce strong stress perturbations on the LVRS flanks thereby inducing a significant increase in the compressive normal stresses. In addition, to account for the rate factor of the pressure solution process, a creep law was adopted to simulate growth and coalescence of the LVRSs. Using the calculated normal compressive stresses and volumetric plastic strains as proxy for the growth, we show that (1) a single LVRS is able to grow both laterally and transversely for a short distance and (2) two in-plane aligned neighboring LVRSs with a short distance between the adjacent tips and two parallel echelon and overlapped LVRSs with a small spacing may be able to link and coalesce to form a longer and wider LVRS, respectively. The influences of the LVRS geometric configurations, the material properties within the LVRSs, and the distance and spacing of the aligned in-plane, echelon, and overlapping neighboring parallel LVRSs on the growth and coalescence of the LVRSs are investigated and their

  14. Metal thin film growth on multimetallic surfaces: From quaternary metallic glass to binary crystal

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Dapeng [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    The work presented in this thesis mainly focuses on the nucleation and growth of metal thin films on multimetallic surfaces. First, we have investigated the Ag film growth on a bulk metallic glass surface. Next, we have examined the coarsening and decay of bilayer Ag islands on NiAl(110) surface. Third, we have investigated the Ag film growth on NiAl(110) surface using low-energy electron diffraction (LEED). At last, we have reported our investigation on the epitaxial growth of Ni on NiAl(110) surface. Some general conclusions can be drawn as follows. First, Ag, a bulk-crystalline material, initially forms a disordered wetting layer up to 4-5 monolayers on Zr-Ni-Cu-Al metallic glass. Above this coverage, crystalline 3D clusters grow, in parallel with the flatter regions. The cluster density increases with decreasing temperature, indicating that the conditions of island nucleation are far-from-equilibrium. Within a simple model where clusters nucleate whenever two mobile Ag adatoms meet, the temperature-dependence of cluster density yields a (reasonable) upper limit for the value of the Ag diffusion barrier on top of the Ag wetting layer of 0.32 eV. Overall, this prototypical study suggests that it is possible to grow films of a bulk-crystalline metal that adopt the amorphous character of a glassy metal substrate, if film thickness is sufficiently low. Next, the first study of coarsening and decay of bilayer islands has been presented. The system was Ag on NiAl(110) in the temperature range from 185 K to 250 K. The coarsening behavior, has some similarities to that seen in the Ag(110) homoepitaxial system studied by Morgenstern and co-workers. At 185 K and 205 K, coarsening of Ag islands follows a Smoluchowski ripening pathway. At 205 K and 250 K, the terrace diffusion limited Ostwald ripening dominants. The experimental observed temperature for the transition from SR to OR is 205 K. The SR exhibits anisotropic island diffusion and the OR exhibits 1D decay of island

  15. Mechanisms for Solidification Crack Initiation and Growth in Aluminum Welding

    Science.gov (United States)

    Coniglio, N.; Cross, C. E.

    2009-11-01

    In the present work, mechanisms are proposed for solidification crack initiation and growth in aluminum alloy 6060 arc welds. Calculations for an interdendritic liquid pressure drop, made using the Rappaz-Drezet-Gremaud (RDG) model, demonstrate that cavitation as a liquid fracture mechanism is not likely to occur except at elevated levels of hydrogen content. Instead, a porosity-based crack initiation model has been developed based upon pore stability criteria, assuming that gas pores expand from pre-existing nuclei. Crack initiation is taken to occur when stable pores form within the coherent dendrite region, depending upon hydrogen content. Following initiation, crack growth is modeled using a mass balance approach, controlled by local strain rate conditions. The critical grain boundary liquid deformation rate needed for solidification crack growth has been determined for a weld made with a 16 pct 4043 filler addition, based upon the local strain rate measurement and a simplified strain rate partitioning model. Combined models show that hydrogen and strain rate control crack initiation and growth, respectively. A hypothetical hydrogen strain rate map is presented, defining conceptually the combined conditions needed for cracking and porosity.

  16. Boehmite (AlOOH) nanostrips and their growth mechanism

    KAUST Repository

    Dar, Farooq Ahmad

    2015-02-04

    Crystalline nanostrips of AlOOH have been prepared at 240∘C through a fast route. Powder X-ray diffraction studies reveal that the as-prepared nanostrips are highly crystalline in nature and by morphological investigations using FESEM, it was revealed that the strips have average length of 210 nm and width of 60 ± 20 nm. A plausible theory is proposed which reveals the growth mechanism of nanostrips.

  17. Growth and characterization of multiferroic barium titanate-cobalt ferrite thin film nanostructures

    Science.gov (United States)

    Zheng, Haimei

    Multiferroic materials which display simultaneous ferroelectricity and magnetism have been stimulating significant interest both from the basic science and application point of view. It was proposed that composites with one piezoelectric phase and one magnetostrictive phase can be magnetoelectrically coupled via a stress mediation. The coexistence of magnetic and electric subsystems as well as the magnetoelectric effect of the material allows an additional degree of freedom in the design of actuators, transducers, and storage devices. Previous work on such materials has been focused on bulk ceramics. In the present work, we created vertically aligned multiferroic BaTiO 3-CoFe2O4 thin film nanostructures using pulsed laser deposition. Spinel CoFe2O4 and perovskite BaTiO 3 spontaneously separated during the film growth. CoFe2O 4 forms nano-pillar arrays embedded in a BaTiO3 matrix, which show three-dimensional heteroepitaxy. CoFe2O4 pillars have uniform size and spacing. As the growth temperature increases the lateral size of the pillars also increases. The size of the CoFe2O 4 pillars as a function of growth temperature at a constant growth rate follows an Arrhenius behaviour. The formation of the BaTiO3-CoFe 2O4 nanostructures is a process directed by both thermodynamic equilibrium and kinetic diffusion. Lattice mismatch strain, interface energy, elastic moduli and molar ratio of the two phases, etc., are considered to play important roles in the growth dynamics leading to the nanoscale pattern formation of BaTiO3-CoFe2O4 nanostructures. Magnetic measurements exhibit that all the films have a large uniaxial magnetic anisotropy with an easy axis normal to the film plane. It was calculated that stress anisotropy is the main contribution to the anisotropy field. We measured the ferroelectric and piezoelectric properties of the films, which correspond to the present of BaTiO3 phase. The system shows a strong coupling of the two order parameters of polarization and

  18. Film growth, adsorption and desorption kinetics of indigo on SiO2

    International Nuclear Information System (INIS)

    Scherwitzl, Boris; Resel, Roland; Winkler, Adolf

    2014-01-01

    Organic dyes have recently been discovered as promising semiconducting materials, attributable to the formation of hydrogen bonds. In this work, the adsorption and desorption behavior, as well as thin film growth was studied in detail for indigo molecules on silicon dioxide with different substrate treatments. The material was evaporated onto the substrate by means of physical vapor deposition under ultra-high vacuum conditions and was subsequently studied by Thermal Desorption Spectroscopy (TDS), Auger Electron Spectroscopy, X-Ray Diffraction, and Atomic Force Microscopy. TDS revealed initially adsorbed molecules to be strongly bonded on a sputter cleaned surface. After further deposition a formation of dimers is suggested, which de-stabilizes the bonding mechanism to the substrate and leads to a weakly bonded adsorbate. The dimers are highly mobile on the surface until they get incorporated into energetically favourable three-dimensional islands in a dewetting process. The stronger bonding of molecules within those islands could be shown by a higher desorption temperature. On a carbon contaminated surface no strongly bonded molecules appeared initially, weakly bonded monomers rather rearrange into islands at a surface coverage that is equiv