WorldWideScience

Sample records for silica film structure

  1. Atomic Structure Control of Silica Thin Films on Pt(111)

    KAUST Repository

    Crampton, Andrew S

    2015-05-27

    Metal oxide thin films grown on metal single crystals are commonly used to model heterogeneous catalyst supports. The structure and properties of thin silicon dioxide films grown on metal single crystals have only recently been thoroughly characterized and their spectral properties well established. We report the successful growth of a three- dimensional, vitreous silicon dioxide thin film on the Pt(111) surface and reproduce the closed bilayer structure previously reported. The confirmation of the three dimensional nature of the film is unequivocally shown by the infrared absorption band at 1252 cm−1. Temperature programmed desorption was used to show that this three-dimensional thin film covers the Pt(111) surface to such an extent that its application as a catalyst support for clusters/nanoparticles is possible. The growth of a three-dimensional film was seen to be directly correlated with the amount of oxygen present on the surface after the silicon evaporation process. This excess of oxygen is tentatively attributed to atomic oxygen being generated in the evaporator. The identification of atomic oxygen as a necessary building block for the formation of a three-dimensional thin film opens up new possibilities for thin film growth on metal supports, whereby simply changing the type of oxygen enables thin films with different atomic structures to be synthesized. This is a novel approach to tune the synthesis parameters of thin films to grow a specific structure and expands the options for modeling common amorphous silica supports under ultra high vacuum conditions.

  2. Structure and mechanical properties of silica doped zirconia thin films

    Energy Technology Data Exchange (ETDEWEB)

    Uhlmann, Ina, E-mail: uhlmann@ceramics.tu-darmstadt.de [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Hawelka, Dominik [Fraunhofer Institute for Laser Technology ILT, 52074 Aachen (Germany); Hildebrandt, Erwin [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Pradella, Jens [Merck KGaA Darmstadt, 64293 Darmstadt (Germany); Rödel, Jürgen [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany)

    2013-01-01

    Sol–gel based wear resistant coatings are presented as an alternative to existing vapor deposition coatings. The films consist of zirconia which has been doped with 8 wt.% silica. Crack-free single as well as multilayer coatings with thicknesses of 80 and 150 nm, respectively, could be produced after sintering at 1000 °C. The evolution of layer thickness, optical, chemical and mechanical properties during film annealing was investigated by ellipsometry, scanning electron microscopy, thermal gravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, nanoindentation and micro-abrasion. Micro-abrasion has been established as an easy and powerful tool to achieve first comparative abrasion data which could be correlated to hardness, Young's modulus and structure of the films. Above 600 °C a tetragonal, oxide coating with a Young's modulus ranging from 80 to 90 GPa, a hardness from 7 to 8 GPa and an increased abrasion resistance was obtained. The film density reached 4.64 g/cm{sup 3} with the mean refractive index n{sub 550} {sub nm} lying between 1.88 and 1.93. - Highlights: ► Sol–gel zirconia–8 wt.% silica coatings with hardness up to 8 GPa achieved ► Layer thickness as compared by ellipsometry and scanning electron microscopy ► Crack-free multilayer coatings produced up to 150 nm.

  3. Atomic Structure Control of Silica Thin Films on Pt(111)

    KAUST Repository

    Crampton, Andrew S; Ridge, Claron J.; Rö tzer, Marian David; Zwaschka, Gregor; Braun, Thomas; D'Elia, Valerio; Basset, Jean-Marie; Schweinberger, Florian Frank; Gü nther, Sebastian; Heiz, Ueli

    2015-01-01

    Metal oxide thin films grown on metal single crystals are commonly used to model heterogeneous catalyst supports. The structure and properties of thin silicon dioxide films grown on metal single crystals have only recently been thoroughly

  4. Pore Structure Control of Ordered Mesoporous Silica Film Using Mixed Surfactants

    Directory of Open Access Journals (Sweden)

    Tae-Jung Ha

    2011-01-01

    Full Text Available Materials with nanosized and well-arranged pores have been researched actively in order to be applied to new technology fields. Especially, mesoporous material containing various pore structures is expected to have different pore structure. To form a mixed pore structure, ordered mesoporous silica films were prepared with a mixture of surfactant; Brij-76 and P-123 block copolymer. In mixed surfactant system, mixed pore structure was observed in the region of P-123/(Brij-76 + P-123 with about 50.0 wt.% while a single pore structure was observed in regions which have large difference in ratio between Brij-76 and P-123 through the X-ray diffraction analysis. Regardless of surfactant ratio, porosity was retained almost the same. It is expected that ordered mesoporous silica film with mixed pore structure can be one of the new materials which has distinctive properties.

  5. Structure and properties of low-n mesoporous silica films for optical applications

    International Nuclear Information System (INIS)

    Konjhodzic, Denan; Bretinger, Helmut; Marlow, Frank

    2006-01-01

    The properties and structure of the mesoporous silica films synthesized by dip-coating in evaporation-induced self-assembly are investigated. The nonionic triblock copolymer EO 2 PO 7 EO 2 has been used as a template in this modified sol-gel process. A strong dependence of the formed structure on the processing conditions, especially humidity, has been revealed allowing an appreciable structure tuning. Low humidity allows the reproducible synthesis of low refractive index films, which were used as optical waveguide supports. They are crack-free, transparent, thermally stable, very smooth, and have a thickness up to 1 μm. Under higher humidity conditions a novel sustained lamellar structure was synthesized, that remains stable upon calcination. The films were characterized by angle-dependent interferometry, small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). 2D photonic crystals made of different materials, such as polymers can be deposited onto these films

  6. Influence of p H on optical properties of nano structure sol-gel-derived silica films

    International Nuclear Information System (INIS)

    Heshmatpuor, F.; Adelkhani, H.; Nahavandi, M.; Noorbakhsh Shourabadi, M.

    2006-01-01

    Sol-gel derived silica films were fabricated by dip-coating onto glass microscope substrates. Film properties such as transmission and surface morphology were monitored as function of dip speed and sol p H. Film transmission was increased with increasing of p H in visible range. The surface morphology of films were investigated with scanning electron microscopy.

  7. X-ray spectroscopy study of electronic structure of laser-irradiated Au nanoparticles in a silica film

    International Nuclear Information System (INIS)

    Jonnard, P.; Bercegol, H.; Lamaignere, L.; Morreeuw, J.-P.; Rullier, J.-L.; Cottancin, E.; Pellarin, M.

    2005-01-01

    The electronic structure of gold nanoparticles embedded in a silica film is studied, both before and after irradiation at 355 nm by a laser. The Au 5d occupied valence states are observed by x-ray emission spectroscopy. They show that before irradiation the gold atoms are in metallic states within the nanoparticles. After irradiation with a fluence of 0.5 J/cm 2 , it is found that gold valence states are close to those of a metal-poor gold silicide; thanks to a comparison of the experimental Au 5d states with the calculated ones for gold silicides using the density-functional theory. The formation of such a compound is driven by the diffusion of the gold atoms into the silica film upon the laser irradiation. At higher fluence, 1 J/cm 2 , we find a higher percentage of metallic gold that could be attributed to annealing in the silica matrix

  8. Replication of butterfly wing and natural lotus leaf structures by nanoimprint on silica sol-gel films

    International Nuclear Information System (INIS)

    Saison, Tamar; Peroz, Christophe; Chauveau, Vanessa; Sondergard, Elin; Arribart, Herve; Berthier, Serge

    2008-01-01

    An original and low cost method for the fabrication of patterned surfaces bioinspired from butterfly wings and lotus leaves is presented. Silica-based sol-gel films are thermally imprinted from elastomeric molds to produce stable structures with superhydrophobicity values as high as 160 deg. water contact angle. The biomimetic surfaces are demonstrated to be tuned from superhydrophobic to superhydrophilic by annealing between 200 deg. C and 500 deg. C

  9. Replication of butterfly wing and natural lotus leaf structures by nanoimprint on silica sol-gel films

    Energy Technology Data Exchange (ETDEWEB)

    Saison, Tamar; Peroz, Christophe; Chauveau, Vanessa; Sondergard, Elin; Arribart, Herve [Unite mixte CNRS/Saint Gobain Saint Gobain Recherche, BP135, 93303 Aubervilliers (France); Berthier, Serge [Institut des Nanosciences de Paris, UMR 7588, CNRS, Universite Pierre et Marie Curie-Paris 6, 140 rue Lourmel, 75015 Paris (France)], E-mail: cperoz@lbl.gov

    2008-12-01

    An original and low cost method for the fabrication of patterned surfaces bioinspired from butterfly wings and lotus leaves is presented. Silica-based sol-gel films are thermally imprinted from elastomeric molds to produce stable structures with superhydrophobicity values as high as 160 deg. water contact angle. The biomimetic surfaces are demonstrated to be tuned from superhydrophobic to superhydrophilic by annealing between 200 deg. C and 500 deg. C.

  10. Facile fabrication of nano-structured silica hybrid film with superhydrophobicity by one-step VAFS approach

    Science.gov (United States)

    Jia, Yi; Yue, Renliang; Liu, Gang; Yang, Jie; Ni, Yong; Wu, Xiaofeng; Chen, Yunfa

    2013-01-01

    Here we report a novel one-step vapor-fed aerosol flame synthesis (VAFS) method to attain silica hybrid film with superhydrophobicity on normal glass and other engineering material substrates using hexamethyldisiloxane (HMDSO) as precursor. The deposited nano-structured silica films represent excellent superhydrophobicity with contact angle larger than 150° and sliding angle below 5°, without any surface modification or other post treatments. SEM photographs proved that flame-made SiO2 nanoparticles formed dual-scale surface roughness on the substrates. It was confirmed by FTIR and XPS that the in situ formed organic fragments on the particle surface as species like (CH3)xSiO2-x/2 (x = 1, 2, 3) which progressively lowered the surface energy of fabricated films. Thus, these combined dual-scale roughness and lowered surface energy cooperatively produced superhydrophobic films. IR camera had been used to monitor the real-time flame temperature. It is found that the inert dilution gas inflow played a critical role in attaining superhydrophobicity due to its cooling and anti-oxidation effect. This method is facile and scalable for diverse substrates, without any requirement of complex equipments and multiple processing steps. It may contribute to the industrial fabrication of superhydrophobic films.

  11. Diffusion structural analysis study of titania films deposited by sol-gel technique on silica glass

    Czech Academy of Sciences Publication Activity Database

    Balek, V.; Mitsuhashi, T.; Bountseva, I.M.; Haneda, H.; Málek, Z.; Šubrt, Jan

    2003-01-01

    Roč. 26, 1-3 (2003), s. 185-189 ISSN 0928-0707. [International Workshop on Glasses, Ceramics, Hybrids and Nanocomposites from Gels /11./. Abano Terme, 16.09.2001-21.09.2001] Institutional research plan: CEZ:AV0Z4032918 Keywords : titania film * diffusion structural analysis * sol-gel Subject RIV: CA - Inorganic Chemistry Impact factor: 1.546, year: 2003

  12. Molecular Structure and Dynamics in Thin Water Films at the Silica and Graphite Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Argyris, Dr. Dimitrios [University of Oklahoma; Tummala, Dr. Naga Rajesh [University of Oklahoma; StrioloDr., A [Vanderbilt University; Cole, David R [ORNL

    2008-01-01

    The structure and dynamic properties of interfacial water at the graphite and silica solid surfaces were investigated using molecular dynamics simulations. The effect of surface properties on the characteristics of interfacial water was quantified by computing density profiles, radial distribution functions, surface density distributions, orientation order parameters, and residence and reorientation correlation functions. In brief, our results show that the surface roughness, chemical heterogeneity, and surface heterogeneous charge distribution affect the structural and dynamic properties of the interfacial water molecules, as well as their rate of exchange with bulk water. Most importantly, our results indicate the formation of two distinct water layers at the SiO2 surface covered by a large density of hydroxyl groups. Further analysis of the data suggests a highly confined first layer where the water molecules assume preferential hydrogen-down orientation and a second layer whose behavior and characteristics are highly dependent on those of the first layer through a well-organized hydrogen bond network. The results suggest that water-water interactions, in particular hydrogen bonds, may be largely responsible for macroscopic interfacial properties such as adsorption and contact angle.

  13. Structural evolution of nanoporous silica thin films studied by positron annihilation spectroscopy and Fourier transform infrared spectroscopy

    International Nuclear Information System (INIS)

    Patel, N; Mariazzi, S; Toniutti, L; Checchetto, R; Miotello, A; Dire, S; Brusa, R S

    2007-01-01

    Three series of silica thin films with thicknesses in the 300 nm range were deposited by spin coating on Si substrates using different compositions of the sol precursors. Film samples were thermally treated in static air at temperatures ranging from 300 to 900 deg. C. The effect of sol precursors and thermal treatment temperature on the film porosity was analysed by Fourier transform infrared (FTIR) spectroscopy, depth profiling with positron annihilation spectroscopy (DP-PAS) and the analysis of the capacitance-voltage (C-V) characteristic. The maximum of the total porosity was found to occur at a temperature of 600 deg. C when removal of porogen and OH groups was completed. Film densification due to the collapsing of the pores was observed after drying at 900 deg. C. DP-PAS provides evidence that the increase in the total porosity is related to a progressive increase in the pore size. The increase in the pore size never gives rise to the onset of connected porosity. In the silica film samples prepared using a low acidity sol precursor, the pore size is always lower than 1 nm. By increasing the acid catalyst ratio in the sol, larger pores are formed. Pores with size larger than 2.3 nm can be obtained by adding porogen to the sol. In each series of silica film samples the shift of the antisymmetric Si-O-Si transversal optical (TO 3 ) mode upon thermal treatment correlates with a change of the pore size as evidenced by DP-PAS analysis. The pore microstructure of the three series of silica films is different at all the examined treatment temperatures and depends on the composition of the precursor sol

  14. Structural evolution of nanoporous silica thin films studied by positron annihilation spectroscopy and Fourier transform infrared spectroscopy

    Science.gov (United States)

    Patel, N.; Mariazzi, S.; Toniutti, L.; Checchetto, R.; Miotello, A.; Dirè, S.; Brusa, R. S.

    2007-09-01

    Three series of silica thin films with thicknesses in the 300 nm range were deposited by spin coating on Si substrates using different compositions of the sol precursors. Film samples were thermally treated in static air at temperatures ranging from 300 to 900 °C. The effect of sol precursors and thermal treatment temperature on the film porosity was analysed by Fourier transform infrared (FTIR) spectroscopy, depth profiling with positron annihilation spectroscopy (DP-PAS) and the analysis of the capacitance-voltage (C-V) characteristic. The maximum of the total porosity was found to occur at a temperature of 600 °C when removal of porogen and OH groups was completed. Film densification due to the collapsing of the pores was observed after drying at 900 °C. DP-PAS provides evidence that the increase in the total porosity is related to a progressive increase in the pore size. The increase in the pore size never gives rise to the onset of connected porosity. In the silica film samples prepared using a low acidity sol precursor, the pore size is always lower than 1 nm. By increasing the acid catalyst ratio in the sol, larger pores are formed. Pores with size larger than 2.3 nm can be obtained by adding porogen to the sol. In each series of silica film samples the shift of the antisymmetric Si-O-Si transversal optical (TO3) mode upon thermal treatment correlates with a change of the pore size as evidenced by DP-PAS analysis. The pore microstructure of the three series of silica films is different at all the examined treatment temperatures and depends on the composition of the precursor sol.

  15. Densification of zirconia films by coevaporation with silica

    International Nuclear Information System (INIS)

    Feldman, A.; Farabaugh, E.N.

    1985-04-01

    Optical films of zirconia have been receiving considerable attention because of their potential use as the high-index layer in multilayer optical coatings for the ultraviolet portion of the spectrum. Several problems are associated with electron-beam deposited zirconia films, including index instability and index inhomogeneity. The index instability is caused by the adsorption and the desorption of water in the porous columnar structure of the zirconia films. Index inhomogeneity is due to the inhomogeneous structure in the films. Recent work has shown that the first several tens of nanometers of a film possess a cubic structure, whereas the outmost layers possess a monoclinic structure. One approach for producing bulk-like zirzonia films that is receiving considerable attention at present is ion-assisted electron-beam deposition. This is because the method has successfully produced zirconia films having bulk-like densities and refractive indices that show insignificant sensitivity to water adsorption. In this paper a similar effect is demonstrated when mixed zirconia:silica films are produced by coevaporation from independent electron-beam sources, and, in particular, it is shown that the admixture of a small amount of silica with the zirconia produces a film possessing a higher refractive index than a pure zirconia film

  16. Positron annihilation studies of mesoporous silica films using a slow positron beam

    International Nuclear Information System (INIS)

    He Chunqing; Muramatsu, Makoto; Ohdaira, Toshiyuki; Kinomura, Atsushi; Suzuki, Ryoichi; Ito, Kenji; Kabayashi, Yoshinori

    2006-01-01

    Positron annihilation lifetime spectra were measured for mesoporous silica films, which were synthesized using triblock copolymer (EO 106 PO 70 EO 106 ) as a structure-directing agent. Different positron lifetime spectra for the deposited and calcined films indicated the formation of meso-structure after calcination, which was confirmed by Fourier transform infrared (FTIR) spectra and field emission-scanning electron microscopy (FE-SEM) observation. Open porosity or pore interconnectivity of a silica film might be evaluated by a two-dimensional positron annihilation lifetime spectrum of an uncapped film. Pore sizes and their distributions in the silica films were found to be affected by thermal treatments

  17. Liquid phase deposition of silica: Thin films, colloids and fullerenes

    Science.gov (United States)

    Whitsitt, Elizabeth A.

    Little research has been done to explore liquid phase deposition (LPD) of silica on non-planar substrates. This thesis proves that the seeded growth of silica colloids from fullerene and surfactant micelles is possible via LPD, as is the coating of individual single walled carbon nanotubes (SWNTs) and carbon fibers. Working on the premise that a molecular growth mechanism (versus colloidal/gel deposition) is valid for LPD, nanostructured substrates and specific chemical functional groups should act as "seeds," or templates, for silica growth. Seeded growth is confirmed by reactions of the growth solution with a range of surfactants and with materials with distinctive surface moieties. LPD promises lower production costs and environmental impact as compared to present methods of coating technology, because it is an inherently simple process, using low temperatures and inexpensive air-stable reactants. Silica is ubiquitous in materials science. Its applications range from thixotropic additives for paint to gate dielectrics in the semiconductor industry. Nano-structured coatings and thin films are integral in today's electronics industry and will become more vital as the size of electronics shrinks. With the incorporation of nanoparticles in future devices, the ability to deposit quality coatings with finely tuned properties becomes paramount. The methods developed herein have applications in fabricating insulators for use in the future molecular scale electronics industry. Additionally, these silica nanoparticles have applications as templates for use in photonics and fuel cell membrane production and lend strength and durability to composites.

  18. Tunable pores in mesoporous silica films studied using a pulsed slow positron beam

    International Nuclear Information System (INIS)

    He Chunqing; Muramatsu, Makoto; Ohdaira, Toshiyuki; Oshima, Nagayasu; Kinomura, Atsushi; Suzuki, Ryoichi; Kobayashi, Yoshinori

    2007-01-01

    Positron annihilation lifetime spectroscopy (PALS) based on a pulsed slow positron beam was applied to study mesoporous silica films, synthesized using amphiphilic PEO-PPO-PEO triblock copolymers as structure-directing agents. The pore size depends on the loading of different templates. Larger pores were formed in silica films templated by copolymers with higher molecular-weights. Using 2-dimensional PALS, open porosity of silica films was also found to be influenced by the molecular-weight as well as the ratio of hydrophobic PPO moiety of the templates

  19. Design of a superhydrophobic and superoleophilic film using cured fluoropolymer@silica hybrid

    International Nuclear Information System (INIS)

    Yang, Hao; Pi, Pihui; Yang, Zhuo-ru; Lu, Zhong; Chen, Rong

    2016-01-01

    Graphical abstract: - Highlights: • Cured fluoropolymer@silica hybrid was coated on stainless steel mesh. • The hybrid film showed superhydrophobicity and superoleophilicity by adjusting silica dosage. • The hybrid film exhibited good thermal stability and excellent oil/water separation efficiency. - Abstract: Recently, considerable efforts have been made on superhydrophobic–superoleophilic filter to satisfy the requirements of the applications to oil/water separation. In this work, we obtained a superhydrophobic and superoleophilic film by coating cured fluoropolymer@silica hybrid on stainless steel mesh. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric-differential scanning calorimetry (TG-DSC) were used to determine the chemical composition and thermal stability of the sample. The effect of silica nanoparticles (NPs) concentration on the surface property of the hybrid film was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle analyzer. The results indicate that silica NPs not only enhance the thermal stability, but also strengthen the hydrophobicity and oleophilicity of the film. When 20 wt% silica NPs was added into the thermosetting fluoropolymer, the hybrid film shows both superhydrophobicity and superoleophilicity owing to the large surface roughness factor (RMS) and porous structure. Moreover, the hybrid film could be used to separate water from different oils effectively. When the pore size of the mesh is less than 300 μm, the oil/water separation efficiency of the film reaches above 99%, which shows a great potential application to dehydrate fuel oils.

  20. Design of a superhydrophobic and superoleophilic film using cured fluoropolymer@silica hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hao [Key Laboratory for Green Chemical Process of Ministry of Education and School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Xiongchu Street, Wuhan, 430073 (China); Pi, Pihui; Yang, Zhuo-ru [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640 (China); Lu, Zhong [Key Laboratory for Green Chemical Process of Ministry of Education and School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Xiongchu Street, Wuhan, 430073 (China); Chen, Rong, E-mail: rchenhku@hotmail.com [Key Laboratory for Green Chemical Process of Ministry of Education and School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Xiongchu Street, Wuhan, 430073 (China)

    2016-12-01

    Graphical abstract: - Highlights: • Cured fluoropolymer@silica hybrid was coated on stainless steel mesh. • The hybrid film showed superhydrophobicity and superoleophilicity by adjusting silica dosage. • The hybrid film exhibited good thermal stability and excellent oil/water separation efficiency. - Abstract: Recently, considerable efforts have been made on superhydrophobic–superoleophilic filter to satisfy the requirements of the applications to oil/water separation. In this work, we obtained a superhydrophobic and superoleophilic film by coating cured fluoropolymer@silica hybrid on stainless steel mesh. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric-differential scanning calorimetry (TG-DSC) were used to determine the chemical composition and thermal stability of the sample. The effect of silica nanoparticles (NPs) concentration on the surface property of the hybrid film was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle analyzer. The results indicate that silica NPs not only enhance the thermal stability, but also strengthen the hydrophobicity and oleophilicity of the film. When 20 wt% silica NPs was added into the thermosetting fluoropolymer, the hybrid film shows both superhydrophobicity and superoleophilicity owing to the large surface roughness factor (RMS) and porous structure. Moreover, the hybrid film could be used to separate water from different oils effectively. When the pore size of the mesh is less than 300 μm, the oil/water separation efficiency of the film reaches above 99%, which shows a great potential application to dehydrate fuel oils.

  1. Preparation of mesoporous silica films SBA-15 over different substrates

    International Nuclear Information System (INIS)

    Campos, V.O.; Sousa, E.M.B. de; Macedo, W.A.A.

    2010-01-01

    Mesoporous materials have been target of frequent interest due to its wide application possibilities, for example development of gas sensors, catalysis, molecules transportation, pharmaceuticals release, synthesis of auto-organized nanostructures, among others. The possibilities of application are enhanced when such materials are disposed in the form of thin and ultrathin films. In this work the preparation of mesoporous SBA-15 silica films is explored by means of the dipcoating technique of a sol-gel on different substrates (glass slides, stainless steel, copper), using the surfactant poly(ethylene glycol)-block-poly(propylene glycol)- block-poly(ethylene glycol), known as P123, a block copolymer. Synthesis parameters surfactant concentration, aging time and temperature were investigated. In this work we present the morphological and structural characterization of the prepared films, which were obtained using atomic force microscopy and x-ray fluorescence and diffraction. (author)

  2. Micropatterned Silica Films with Nanohydroxyapatite for Y-TZP Implants.

    Science.gov (United States)

    Miranda, R B P; Grenho, L; Carvalho, A; Fernandes, M H; Monteiro, F J; Cesar, P F

    2018-03-01

    This investigation aimed at developing micropatterned silica thin films (MSTFs) containing nanohydroxyapatite (nano-HA) microaggregates that were not completely covered by silica so that they could directly interact with the surrounding cells. The objectives were 1) to evaluate the effect of the presence of 2 films (MSTF with or without nano-HA addition) on the characteristic strength (σ 0 ) and Weibull modulus ( m) of a yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and 2) to evaluate the effect of these 2 films, as applied onto the Y-TZP surface, on the morphology, orientation, and proliferation of MG63 cells. Sol-gel process and soft lithography were used to apply the MSTF onto the Y-TZP specimens. Three experimental groups were produced: Y-TZP, Y-TZP + MSTF, and Y-TZP + MSTF + sprayed nano-HA. All surfaces were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy and tested for 4-point flexural strength ( n = 30) in water at 37 °C. Weibull analysis was used to determine m and σ 0 (maximum likelihood method). In vitro biological behavior was performed with human osteoblast-like cells (MG63). Y-TZP was successfully coated with MSFT and MSFT + nano-HA. Scanning electron microscopy micrographs indicated that the microaggregates of nano-HA were not entirely covered by the silica. There was no statistically significant difference among the experimental groups for σ 0 and m. In the groups containing the films, the cells were elongated and aligned along the lines. The MSFT + nano-HA group showed significantly higher cell metabolic activity than that obtained for the Y-TZP group at day 7. This investigation was successful in producing an MSTF containing nano-HA microaggregates that remained exposed to the environment. The developed films did not jeopardize the structural reliability of a commercial Y-TZP, as confirmed by the Weibull statistics. The MG63 cells seeded over the films became elongated and aligned along the

  3. Characterization of transparent silica films deposited on polymeric materials

    International Nuclear Information System (INIS)

    Teshima, K.; Sugimura, H.; Inoue, Y.; Takai, O.

    2002-01-01

    Silica films were synthesized by capacitively coupled RF PECVD using mixtures of organo-silane and oxygen as a source. The chemical bonding states and compositions of the films deposited were evaluated with FTIR and XPS. Film surfaces and cross-sections were observed by SEM. Oxygen transmission rates (OTR) of the films coated on polyethylene terephthalate (PET) substrates were measured by an isopiestic method. (Authors)

  4. Molecular-dynamics simulations of thin polyisoprene films confined between amorphous silica substrates

    International Nuclear Information System (INIS)

    Guseva, D. V.; Komarov, P. V.; Lyulin, Alexey V.

    2014-01-01

    Constant temperature–constant pressure (NpT) molecular-dynamics computer simulations have been carried out for the united-atom model of a non-crosslinked (1,4) cis-polyisoprene (PI) melt confined between two amorphous, fully coordinated silica surfaces. The Lennard-Jones 12-6 potential was implemented to describe the polymer–silica interactions. The thickness H of the produced PI–silica film has been varied in a wide range, 1 g g is the individual PI chain radius of gyration measured under the imposed confinement. After a thorough equilibration, the PI film stratified structure and polymer segmental dynamics have been studied. The chain structure in the middle of the films resembles that in a corresponding bulk, but the polymer-density profile shows a pronounced ordering of the polymer segments in the vicinity of silica surfaces; this ordering disappears toward the film middles. Tremendous slowing down of the polymer segmental dynamics has been observed in the film surface layers, with the segmental relaxation more than 150 times slower as compared to that in a PI bulk. This effect increases with decreasing the polymer-film thickness. The segmental relaxation in the PI film middles shows additional relaxation process which is absent in a PI bulk. Even though there are fast relaxation processes in the film middle, its overall relaxation is slower as compared to that in a bulk sample. The interpretation of the results in terms of polymer glassy bridges has been discussed

  5. A simple three step method for selective placement of organic groups in mesoporous silica thin films

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Esteban A. [Gerencia Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Av. Gral Paz 1499 (B1650KNA) San Martín, Buenos Aires (Argentina); Llave, Ezequiel de la; Williams, Federico J. [Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, C1428EHA Buenos Aires (Argentina); Soler-Illia, Galo J.A.A., E-mail: galo.soler.illia@gmail.com [Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, C1428EHA Buenos Aires (Argentina); Instituto de Nanosistemas, Universidad Nacional de General San Martín, 25 de Mayo y Francia (1650) San Martín, Buenos Aires (Argentina)

    2016-02-01

    Selective functionalization of mesoporous silica thin films was achieved using a three step method. The first step consists in an outer surface functionalization, followed by washing off the structuring agent (second step), leaving the inner surface of the pores free to be functionalized in the third step. This reproducible method permits to anchor a volatile silane group in the outer film surface, and a second type of silane group in the inner surface of the pores. As a concept test we modified the outer surface of a mesoporous silica film with trimethylsilane (–Si–(CH{sub 3}){sub 3}) groups and the inner pore surface with propylamino (–Si–(CH{sub 2}){sub 3}–NH{sub 2}) groups. The obtained silica films were characterized by Environmental Ellipsometric Porosimetry (EEP), EDS, XPS, contact angle and electron microscopy. The selectively functionalized silica (SF) shows an amount of surface amino functions 4.3 times lower than the one-step functionalized (OSF) silica samples. The method presented here can be extended to a combination of silane chlorides and alkoxides as functional groups, opening up a new route toward the synthesis of multifunctional mesoporous thin films with precisely localized organic functions. - Highlights: • Selective functionalization of mesoporous silica thin films was achieved using a three step method. • A volatile silane group is anchored by evaporation on the outer film surface. • A second silane is deposited in the inner surface of the pores by post-grafting. • Contact angle, EDS and XPS measurements show different proportions of amino groups on both surfaces. • This method can be extended to a combination of silane chlorides and alkoxides functional groups.

  6. Influence of Nano Silica on Alkyd Films

    DEFF Research Database (Denmark)

    Nikolic, Miroslav

    . The present work centers on the reinforcement of alkyd binders emulsified in water and used in exterior wood coatings with nano silica. Raman spectroscopy was used throughout the study to maintain the reproducibility of results as it was found that colloidal nano silica can increase or decrease the speed...... of alkyd curing affecting the tested mechanical properties. Hydrophilic, colloidal nano silica was seen to have limited effect in improving the mechanical properties due to problems in properly dispersing and attaining good surface interactions with the hydrophobic alkyd polymer. Efforts in increasing...... the interactions with the alkyd polymer while keeping the nano filler stable in the water phase did not show further improvements of mechanical properties. The best results in respect to mechanical properties, as measured under static and dynamic loading, were obtained with the use of hexamethyldisilazane treated...

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

    Directory of Open Access Journals (Sweden)

    S. Abdalla

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

  8. Hydrophobic and optical characteristics of graphene and graphene oxide films transferred onto functionalized silica particles deposited glass surface

    Science.gov (United States)

    Yilbas, B. S.; Ibrahim, A.; Ali, H.; Khaled, M.; Laoui, T.

    2018-06-01

    Hydrophobic and optical transmittance characteristics of the functionalized silica particles on the glass surface prior and after transfer of graphene and graphene oxide films on the surface are examined. Nano-size silica particles are synthesized and functionalized via chemical grafting and deposited onto a glass surface. Graphene film, grown on copper substrate, was transferred onto the functionalized silica particles surface through direct fishing method. Graphene oxide layer was deposited onto the functionalized silica particles surface via spin coating technique. Morphological, hydrophobic, and optical characteristics of the functionalized silica particles deposited surface prior and after graphene and graphene oxide films transfer are examined using the analytical tools. It is found that the functionalized silica particles are agglomerated at the surface forming packed structures with few micro/nano size pores. This arrangement gives rise to water droplet contact angle and contact angle hysteresis in the order of 163° and 2°, respectively, and remains almost uniform over the entire surface. Transferring graphene and depositing graphene oxide films over the functionalized silica particles surface lowers the water droplet contact angle slightly (157-160°) and increases the contact angle hysteresis (4°). The addition of the graphene and graphene oxide films onto the surface of the deposited functionalized silica particles improves the optical transmittance.

  9. Molecular insight into nanoscale water films dewetting on modified silica surfaces.

    Science.gov (United States)

    Zhang, Jun; Li, Wen; Yan, Youguo; Wang, Yefei; Liu, Bing; Shen, Yue; Chen, Haixiang; Liu, Liang

    2015-01-07

    In this work, molecular dynamics simulations are adopted to investigate the microscopic dewetting mechanism of nanoscale water films on methylated silica surfaces. The simulation results show that the dewetting process is divided into two stages: the appearance of dry patches and the quick contraction of the water film. First, the appearance of dry patches is due to the fluctuation in the film thickness originating from capillary wave instability. Second, for the fast contraction of water film, the unsaturated electrostatic and hydrogen bond interactions among water molecules are the driving forces, which induce the quick contraction of the water film. Finally, the effect of film thickness on water films dewetting is studied. Research results suggest that upon increasing the water film thickness from 6 to 8 Å, the final dewetting patterns experience separate droplets and striation-shaped structures, respectively. But upon further increasing the water film thickness, the water film is stable and there are no dry patches. The microscopic dewetting behaviors of water films on methylated silica surfaces discussed here are helpful in understanding many phenomena in scientific and industrial processes better.

  10. Ordered mesoporous silica materials with complicated structures

    KAUST Repository

    Han, Yu

    2012-05-01

    Periodically ordered mesoporous silicas constitute one of the most important branches of porous materials that are extensively employed in various chemical engineering applications including adsorption, separation and catalysis. This short review gives an introduction to recently developed mesoporous silicas with emphasis on their complicated structures and synthesis mechanisms. In addition, two powerful techniques for solving complex mesoporous structures, electron crystallography and electron tomography, are compared to elucidate their respective strength and limitations. Some critical issues and challenges regarding the development of novel mesoporous structures as well as their applications are also discussed. © 2011 Elsevier Ltd.

  11. Fabrication of semi-transparent super-hydrophobic surface based on silica hierarchical structures

    KAUST Repository

    Chen, Ping-Hei

    2011-01-01

    This study successfully develops a versatile method of producing superhydrophobic surfaces with micro/nano-silica hierarchical structures on glass surfaces. Optically transparent super hydrophobic silica thin films were prepared by spin-coating silica particles suspended in a precursor solution of silane, ethanol, and H2O with molar ratio of 1:4:4. The resulting super hydrophobic films were characterized by scanning electron microscopy (SEM), optical transmission, and contact angle measurements. The glass substrates in this study were modified with different particles: micro-silica particles, nano-silica particles, and hierarchical structures. This study includes SEM micrographs of the modified glass surfaces with hierarchical structures at different magnifications. © 2011 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

  12. Colloidal silica films for high-capacity DNA arrays

    Science.gov (United States)

    Glazer, Marc Irving

    The human genome project has greatly expanded the amount of genetic information available to researchers, but before this vast new source of data can be fully utilized, techniques for rapid, large-scale analysis of DNA and RNA must continue to develop. DNA arrays have emerged as a powerful new technology for analyzing genomic samples in a highly parallel format. The detection sensitivity of these arrays is dependent on the quantity and density of immobilized probe molecules. We have investigated substrates with a porous, "three-dimensional" surface layer as a means of increasing the surface area available for the synthesis of oligonucleotide probes, thereby increasing the number of available probes and the amount of detectable bound target. Porous colloidal silica films were created by two techniques. In the first approach, films were deposited by spin-coating silica colloid suspensions onto flat glass substrates, with the pores being formed by the natural voids between the solid particles (typically 23nm pores, 35% porosity). In the second approach, latex particles were co-deposited with the silica and then pyrolyzed, creating films with larger pores (36 nm), higher porosity (65%), and higher surface area. For 0.3 mum films, enhancements of eight to ten-fold and 12- to 14-fold were achieved with the pure silica films and the films "templated" with polymer latex, respectively. In gene expression assays for up to 7,000 genes using complex biological samples, the high-capacity films provided enhanced signals and performed equivalently or better than planar glass on all other functional measures, confirming that colloidal silica films are a promising platform for high-capacity DNA arrays. We have also investigated the kinetics of hybridization on planar glass and high-capacity substrates. Adsorption on planar arrays is similar to ideal Langmuir-type adsorption, although with an "overshoot" at high solution concentration. Hybridization on high-capacity films is

  13. Structure and Properties of LENRA/ Silica Composite

    International Nuclear Information System (INIS)

    Mahathir Mohamed; Dahlan Mohd

    2010-01-01

    The sol-gel reaction using tetra ethoxysilane (TEOS) was conducted for modified natural rubber (NR) matrix to obtain in situ generated NR/ silica composite. The present of acrylate group in the modified NR chain turns the composite into radiation-curable. The maximum amount of silica generated in the matrix was 50 p hr by weight. During the sol-gel process the inorganic mineral was deposited in the rubber matrix forming hydrogen bonding between organic and inorganic phases. The composites obtained were characterized by various techniques including thermogravimetric analysis and infrared spectrometry to study their molecular structure. The increase in mechanical properties was observed for low silica contents ( 30 p hr) where more silica were generated, agglomerations were observed at the expense of the mechanical properties. From the DMTA data, it shows an increase of the interaction between the rubber and silica phases up to 30 p hr TEOS. Structure and morphology of the heterogeneous system were analyzed by transmission electron microscopy. The average particle sizes of between 150 nm to 300 nm were achieved for the composites that contain less than 20 p hr of TEOS. (author)

  14. Addition of silica nanoparticles to tailor the mechanical properties of nanofibrillated cellulose thin films.

    Science.gov (United States)

    Eita, Mohamed; Arwin, Hans; Granberg, Hjalmar; Wågberg, Lars

    2011-11-15

    Over the last decade, the use of nanocellulose in advanced technological applications has been promoted both due the excellent properties of this material in combination with its renewability. In this study, multilayered thin films composed of nanofibrillated cellulose (NFC), polyvinyl amine (PVAm) and silica nanoparticles were fabricated on polydimethylsiloxane (PDMS) using a layer-by-layer adsorption technique. The multilayer build-up was followed in situ by quartz crystal microbalance with dissipation, which indicated that the PVAm-SiO(2)-PVAm-NFC system adsorbs twice as much wet mass material compared to the PVAm-NFC system for the same number of bilayers. This is accompanied with a higher viscoelasticity for the PVAm-SiO(2)-PVAm-NFC system. Ellipsometry indicated a dry-state thickness of 2.2 and 3.4 nm per bilayer for the PVAm-NFC system and the PVAm-SiO(2)-PVAm-NFC system, respectively. Atomic force microscopy height images indicate that in both systems, a porous network structure is achieved. Young's modulus of these thin films was determined by the Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIMM) technique. The Young's modulus of the PVAm/NFC films was doubled, from 1 to 2 GPa, upon incorporation of silica nanoparticles in the films. The introduction of the silica nanoparticles lowered the refractive index of the films, most probably due to an increased porosity of the films. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Dielectric breakdown in silica-amorphous polymer nanocomposite films: the role of the polymer matrix.

    Science.gov (United States)

    Grabowski, Christopher A; Fillery, Scott P; Westing, Nicholas M; Chi, Changzai; Meth, Jeffrey S; Durstock, Michael F; Vaia, Richard A

    2013-06-26

    The ultimate energy storage performance of an electrostatic capacitor is determined by the dielectric characteristics of the material separating its conductive electrodes. Polymers are commonly employed due to their processability and high breakdown strength; however, demands for higher energy storage have encouraged investigations of ceramic-polymer composites. Maintaining dielectric strength, and thus minimizing flaw size and heterogeneities, has focused development toward nanocomposite (NC) films; but results lack consistency, potentially due to variations in polymer purity, nanoparticle surface treatments, nanoparticle size, and film morphology. To experimentally establish the dominant factors in broad structure-performance relationships, we compare the dielectric properties for four high-purity amorphous polymer films (polymethyl methacrylate, polystyrene, polyimide, and poly-4-vinylpyridine) incorporating uniformly dispersed silica colloids (up to 45% v/v). Factors known to contribute to premature breakdown-field exclusion and agglomeration-have been mitigated in this experiment to focus on what impact the polymer and polymer-nanoparticle interactions have on breakdown. Our findings indicate that adding colloidal silica to higher breakdown strength amorphous polymers (polymethyl methacrylate and polyimide) causes a reduction in dielectric strength as compared to the neat polymer. Alternatively, low breakdown strength amorphous polymers (poly-4-vinylpyridine and especially polystyrene) with comparable silica dispersion show similar or even improved breakdown strength for 7.5-15% v/v silica. At ∼15% v/v or greater silica content, all the polymer NC films exhibit breakdown at similar electric fields, implying that at these loadings failure becomes independent of polymer matrix and is dominated by silica.

  16. Flexible, cathodoluminescent and free standing mesoporous silica films with entrapped quasi-2D perovskites

    Science.gov (United States)

    Vassilakopoulou, Anastasia; Papadatos, Dionysios; Koutselas, Ioannis

    2017-04-01

    The effective entrapment of hybrid organic-inorganic semiconductors (HOIS) into mesoporous polymer-silica hybrid matrices, formed as free standing flexible films, is presented for the first time. A blend of quasi-2D HOIS, simply synthesized by mixing two-dimensional (2D) and three dimensional (3D) HOIS, exhibiting strong photoluminescence, is embedded into porous silica matrices during the sol-gel synthesis, using tetraethylorthosilicate as precursor and Pluronic F-127 triblock copolymer as structure directing agent, under acidic conditions. The final nanostructure hybrid forms flexible, free standing films, presenting high cathodoluminescence and long stable excitonic luminescence, indicating the protective character of the hybrid matrix towards the entrapped perovskite. A significant result is that the photoluminescence of the entrapped HOIS is not affected even after films' prolonged exposure to water.

  17. Reversible Surface Properties of Polybenzoxazine/Silica Nanocomposites Thin Films

    Directory of Open Access Journals (Sweden)

    Wei-Chen Su

    2013-01-01

    Full Text Available We report the reversible surface properties (hydrophilicity, hydrophobicity of a polybenzoxazine (PBZ thin film through simple application of alternating UV illumination and thermal treatment. The fraction of intermolecularly hydrogen bonded O–H⋯O=C units in the PBZ film increased after UV exposure, inducing a hydrophilic surface; the surface recovered its hydrophobicity after heating, due to greater O–H⋯N intramolecular hydrogen bonding. Taking advantage of these phenomena, we prepared a PBZ/silica nanocomposite coating through two simple steps; this material exhibited reversible transitions from superhydrophobicity to superhydrophilicity upon sequential UV irradiation and thermal treatment.

  18. Hydrophobicity of silica thin films: The deconvolution and interpretation by Fourier-transform infrared spectroscopy

    Science.gov (United States)

    Saputra, Riza Eka; Astuti, Yayuk; Darmawan, Adi

    2018-06-01

    This work investigated the synthesis of dimethoxydimethylsilane:tetraethoxysilane (DMDMS:TEOS) silica thin films as well as the effect of DMDMS:TEOS molar ratios and calcination temperature on hydrophobic properties of silica thin films and its correlation with the FTIR spectra behaviour. The silica thin films were synthesized by sol-gel method using combination of DMDMS and TEOS as silica precursors, ethanol as solvent and ammonia as catalyst, with DMDMS and TEOS molar ratio of 10:90, 25:75, 50:50, 75:25 and 90:10. The results showed that DMDMS:TEOS molar ratio had significant impact on the hydrophobic properties of silica thin films coated on a glass surface. Furthermore, the correlation between water contact angle (WCA) and DMDMS:TEOS molar ratio was found to be in a parabolic shape. Concurrently, the maximum apex of the parabola obtained was observed on the DMDMS:TEOS molar ratio of 50:50 for all calcination temperature. It was clearly observed that the silica xerogel exhibiting notable change in relative peak intensities showed FTIR peak splitting of υasymmetric Si-O-Si. To uncover what happened at the FTIR peak, the deconvolution was conducted in Gaussian approach. It was established that the changes in the Gaussian peak component were related to DMDMS:TEOS molar ratios and the calcination temperature that allowed us to tailor the DMDMS:TEOS silica polymer structure model based on the peak intensity ratios. With the increase of DMDMS:TEOS molar ratio, the ratio of (cyclic Si-O-Si)/(linear Si-O-Si) decreased, whilst the ratio of (C-H)/(linear Si-O-Si) increased. Both ratios intersected at DMDMS:TEOS molar ratio of 50:50 with contribution factor ratio of 1:16 and 1:50 for silica xerogel calcined at 300 °C and 500 °C respectively. The importance of this research is the DMDMS:TEOS molar ratio plays an important role in determining the hydrophobic properties of thin films.

  19. Hydrophobicity of silica thin films: The deconvolution and interpretation by Fourier-transform infrared spectroscopy.

    Science.gov (United States)

    Saputra, Riza Eka; Astuti, Yayuk; Darmawan, Adi

    2018-03-14

    This work investigated the synthesis of dimethoxydimethylsilane:tetraethoxysilane (DMDMS:TEOS) silica thin films as well as the effect of DMDMS:TEOS molar ratios and calcination temperature on hydrophobic properties of silica thin films and its correlation with the FTIR spectra behaviour. The silica thin films were synthesized by sol-gel method using combination of DMDMS and TEOS as silica precursors, ethanol as solvent and ammonia as catalyst, with DMDMS and TEOS molar ratio of 10:90, 25:75, 50:50, 75:25 and 90:10. The results showed that DMDMS:TEOS molar ratio had significant impact on the hydrophobic properties of silica thin films coated on a glass surface. Furthermore, the correlation between water contact angle (WCA) and DMDMS:TEOS molar ratio was found to be in a parabolic shape. Concurrently, the maximum apex of the parabola obtained was observed on the DMDMS:TEOS molar ratio of 50:50 for all calcination temperature. It was clearly observed that the silica xerogel exhibiting notable change in relative peak intensities showed FTIR peak splitting of υ asymmetric Si-O-Si. To uncover what happened at the FTIR peak, the deconvolution was conducted in Gaussian approach. It was established that the changes in the Gaussian peak component were related to DMDMS:TEOS molar ratios and the calcination temperature that allowed us to tailor the DMDMS:TEOS silica polymer structure model based on the peak intensity ratios. With the increase of DMDMS:TEOS molar ratio, the ratio of (cyclic Si-O-Si)/(linear Si-O-Si) decreased, whilst the ratio of (C-H)/(linear Si-O-Si) increased. Both ratios intersected at DMDMS:TEOS molar ratio of 50:50 with contribution factor ratio of 1:16 and 1:50 for silica xerogel calcined at 300°C and 500°C respectively. The importance of this research is the DMDMS:TEOS molar ratio plays an important role in determining the hydrophobic properties of thin films. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Thickness controlled sol-gel silica films for plasmonic bio-sensing devices

    Energy Technology Data Exchange (ETDEWEB)

    Figus, Cristiana, E-mail: cristiana.figus@dsf.unica.it; Quochi, Francesco, E-mail: cristiana.figus@dsf.unica.it; Artizzu, Flavia, E-mail: cristiana.figus@dsf.unica.it; Saba, Michele, E-mail: cristiana.figus@dsf.unica.it; Marongiu, Daniela, E-mail: cristiana.figus@dsf.unica.it; Mura, Andrea; Bongiovanni, Giovanni [Dipartimento di Fisica - University of Cagliari, S.P. Km 0.7, I-09042 Monserrato (Canada) (Italy); Floris, Francesco; Marabelli, Franco; Patrini, Maddalena; Fornasari, Lucia [Dipartimento di Fisica - University of Pavia, Via Agostino Bassi 6, I-27100 Pavia (PV) (Italy); Pellacani, Paola; Valsesia, Andrea [Plasmore S.r.l. -Via Grazia Deledda 4, I-21020 Ranco (Vatican City State, Holy See) (Italy)

    2014-10-21

    Plasmonics has recently received considerable interest due to its potentiality in many fields as well as in nanobio-technology applications. In this regard, various strategies are required for modifying the surfaces of plasmonic nanostructures and to control their optical properties in view of interesting application such as bio-sensing, We report a simple method for depositing silica layers of controlled thickness on planar plasmonic structures. Tetraethoxysilane (TEOS) was used as silica precursor. The control of the silica layer thickness was obtained by optimizing the sol-gel method and dip-coating technique, in particular by properly tuning different parameters such as pH, solvent concentration, and withdrawal speed. The resulting films were characterized via atomic force microscopy (AFM), Fourier-transform (FT) spectroscopy, and spectroscopic ellipsometry (SE). Furthermore, by performing the analysis of surface plasmon resonances before and after the coating of the nanostructures, it was observed that the position of the resonance structures could be properly shifted by finely controlling the silica layer thickness. The effect of silica coating was assessed also in view of sensing applications, due to important advantages, such as surface protection of the plasmonic structure.

  1. Preparation of mesoporous silica thin films by photocalcination method and their adsorption abilities for various proteins

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Katsuya, E-mail: katsuya-kato@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Nakamura, Hitomi [National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Yamauchi, Yoshihiro; Nakanishi, Kazuma; Tomita, Masahiro [Department of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8570 (Japan)

    2014-07-01

    Mesoporous silica (MPS) thin film biosensor platforms were established. MPS thin films were prepared from tetraethoxysilane (TEOS) via using sol–gel and spin-coating methods using a poly-(ethylene oxide)-block-poly-(propylene oxide)-block-poly-(ethylene oxide) triblock polymer, such as P123 ((EO){sub 20}(PO){sub 70}(EO){sub 20}) or F127 ((EO){sub 106}(PO){sub 70}(EO){sub 106}), as the structure-directing agent. The MPS thin film prepared using P123 as the mesoporous template and treated via vacuum ultraviolet (VUV) irradiation to remove the triblock copolymer had a more uniform pore array than that of the corresponding film prepared via thermal treatment. Protein adsorption and enzyme-linked immunosorbent assay (ELISA) on the synthesized MPS thin films were also investigated. VUV-irradiated MPS thin films adsorbed a smaller quantity of protein A than the thermally treated films; however, the human immunoglobulin G (IgG) binding efficiency was higher on the former. In addition, protein A–IgG specific binding on MPS thin films was achieved without using a blocking reagent; i.e., nonspecific adsorption was inhibited by the uniform pore arrays of the films. Furthermore, VUV-irradiated MPS thin films exhibited high sensitivity for ELISA testing, and cytochrome c adsorbed on the MPS thin films exhibited high catalytic activity and recyclability. These results suggest that MPS thin films are attractive platforms for the development of novel biosensors. - Highlights: • VUV-treated MPS thin films with removed polymer had uniform pore. • VUV-treated MPS thin films exhibited high sensitivity by ELISA. • Cytochrome c showed the catalytic activity and recyclability on synthesized films.

  2. Preparation of mesoporous silica thin films by photocalcination method and their adsorption abilities for various proteins

    International Nuclear Information System (INIS)

    Kato, Katsuya; Nakamura, Hitomi; Yamauchi, Yoshihiro; Nakanishi, Kazuma; Tomita, Masahiro

    2014-01-01

    Mesoporous silica (MPS) thin film biosensor platforms were established. MPS thin films were prepared from tetraethoxysilane (TEOS) via using sol–gel and spin-coating methods using a poly-(ethylene oxide)-block-poly-(propylene oxide)-block-poly-(ethylene oxide) triblock polymer, such as P123 ((EO) 20 (PO) 70 (EO) 20 ) or F127 ((EO) 106 (PO) 70 (EO) 106 ), as the structure-directing agent. The MPS thin film prepared using P123 as the mesoporous template and treated via vacuum ultraviolet (VUV) irradiation to remove the triblock copolymer had a more uniform pore array than that of the corresponding film prepared via thermal treatment. Protein adsorption and enzyme-linked immunosorbent assay (ELISA) on the synthesized MPS thin films were also investigated. VUV-irradiated MPS thin films adsorbed a smaller quantity of protein A than the thermally treated films; however, the human immunoglobulin G (IgG) binding efficiency was higher on the former. In addition, protein A–IgG specific binding on MPS thin films was achieved without using a blocking reagent; i.e., nonspecific adsorption was inhibited by the uniform pore arrays of the films. Furthermore, VUV-irradiated MPS thin films exhibited high sensitivity for ELISA testing, and cytochrome c adsorbed on the MPS thin films exhibited high catalytic activity and recyclability. These results suggest that MPS thin films are attractive platforms for the development of novel biosensors. - Highlights: • VUV-treated MPS thin films with removed polymer had uniform pore. • VUV-treated MPS thin films exhibited high sensitivity by ELISA. • Cytochrome c showed the catalytic activity and recyclability on synthesized films

  3. 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.

  4. Ageing-induced enhancement of open porosity of mesoporous silica films studied by positron annihilation spectroscopy

    International Nuclear Information System (INIS)

    He Chunqing; Muramatsu, Makoto; Oshima, Nagayasu; Ohdaira, Toshiyuki; Kinomura, Atsushi; Suzuki, Ryoichi

    2006-01-01

    We show that ageing of the silica sol in a closed vessel enhanced the open porosity of calcined mesoporous silica film studied by positron. Positron annihilation lifetime spectroscopy (PALS) based on a pulsed slow positron beam was used to estimate the mesopore size. 2-dimensional PALS (2D-PALS) and ortho-positronium time-of-flight (Ps-TOF) were used to evaluate the open porosity, interconnectivity and tortuosity of mesopores in the silica films. Results revealed that little change in pore size but significant enhancement of open porosity and/or pore interconnectivity occurred in the silica film deposited after the precursor solution aged for a relative longer time

  5. Evaluation of optical properties of the amorphous carbon film on fused silica

    International Nuclear Information System (INIS)

    Baydogan, Nilguen Dogan

    2004-01-01

    Deposition was done using a pulsed filtered cathodic arc with a graphite cathode. The carbon plasma is fully ionised and condenses on the substrate, forming diamond-like material but with amorphous structure. Optical properties of amorphous carbon films on fused-silica glass were investigated and the curves of optical density have a characteristic band at approximately 950 nm. Changes of the colourimetric quantities were evaluated and compared to uncoated fused silica glass. These changes were investigated as a function of the applied substrate bias voltage using the CIE and CIELAB colour systems. It is suggested that the mechanism of absorption is related to an allowed direct transition at the amorphous carbon films on fused silica glass. The optical energy gap of the amorphous carbon film depends on the bias voltage applied to the substrate holder. The optical colour parameters and optical band gap indicated that there is a relation between the dominant wavelength of the reflectance in the visible range and the wavelength of the optical band gap

  6. Structural refinement of vitreous silica bilayers

    Science.gov (United States)

    Sadjadi, Mahdi; Wilson, Mark; Thorpe, M. F.

    The importance of glasses resides not only in their applications but in fundamental questions that they put forth. The continuous random network model can successfully describe the glass structure, but determining details, like ring statistics, has always been difficult using only diffraction data. But recent atomic images of 2D vitreous silica bilayers can offer valuable new insights which are hard to be observed directly in 3D silica models/experiments (for references see). However, the experimental results are prone to uncertainty in atomic positions, systematic errors, and being finite. We employ special boundary conditions developed for such networks to refine the experimental structures. We show the best structure can be found by using various potentials to maximize information gained from the experimental samples. We find a range of densities, the so-called flexibility window, in which tetrahedra are perfect. We compare results from simulations using harmonic potentials, MD with atomic polarizabilities included and DFT. We should thank David Drabold and Bishal Bhattarai for useful discussions. Support through NSF Grant # DMS 1564468 is gratefully acknowledged.

  7. Characterization of fluorinated silica thin films with ultra-low refractive index deposited at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi-Firouzjah, Marzieh [Semnan Science and Technology Park, 3614933578, Shahrood (Iran, Islamic Republic of); Shokri, Babak, E-mail: b-shokri@sbu.ac.ir [Laser & Plasma Research Institute, Shahid Beheshti University, G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of)

    2015-02-27

    Structural and optical properties of low refractive index fluorinated silica (SiO{sub x}C{sub y}F{sub z}) films were investigated. The films were deposited on p-type silicon and polycarbonate substrates by radio frequency plasma enhanced chemical vapor deposition method at low temperatures. A mixture of tetraethoxysilane vapor, oxygen, and CF{sub 4} was used for deposition of the films. The influence of oxygen flow rate on the elemental compositions, chemical bonding states and surface roughness of the films was studied using energy dispersive X-ray analyzer, Fourier transform infrared spectroscopy in reflectance mode and atomic force microscopy, respectively. Effects of chemical bonds of the film matrix on optical properties and chemical stability were discussed. Energy dispersive spectroscopy showed high fluorine content in the SiO{sub x}C{sub y}F{sub z} film matrix which is in the range of 7.6–11.3%. It was concluded that in fluorine content lower than a certain limit, chemical stability of the film enhances, while higher contents of fluorine heighten moisture absorption followed by increasing refractive index. All of the deposited films were highly transparent. Finally, it was found that the refractive index of the SiO{sub x}C{sub y}F{sub z} film was continuously decreased with the increase of the O{sub 2} flow rate down to the minimum value of 1.16 ± 0.01 (at 632.8 nm) having the most ordered and nano-void structure and the least organic impurities. This sample also had the most chemical stability against moisture absorption. - Highlights: • Low deposition temperature and organic precursor led to higher film fluorination. • High fluorine and nanovoid structure led to drastic decrease in the refractive index. • Silica based thin film with ultralow refractive index of 1.16 was produced. • The produced ultralow-n film is highly stable against moisture absorption.

  8. Silica doped with lanthanum sol–gel thin films for corrosion protection

    International Nuclear Information System (INIS)

    Abuín, M.; Serrano, A.; Llopis, J.; García, M.A.; Carmona, N.

    2012-01-01

    We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol–gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties. - Highlights: ► Silica sol–gel films doped with lanthanum ions were synthesized. ► Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. ► La-acetate is an affordable chemical reactive preferred for the industry. ► Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. ► An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

  9. Silica doped with lanthanum sol-gel thin films for corrosion protection

    Energy Technology Data Exchange (ETDEWEB)

    Abuin, M. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Serrano, A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); Llopis, J. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Garcia, M.A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); IMDEA Nanoscience, Fco. Tomas y Valiente 7, 28049 Madrid (Spain); Carmona, N., E-mail: n.carmona@fis.ucm.es [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain)

    2012-06-01

    We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol-gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties. - Highlights: Black-Right-Pointing-Pointer Silica sol-gel films doped with lanthanum ions were synthesized. Black-Right-Pointing-Pointer Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. Black-Right-Pointing-Pointer La-acetate is an affordable chemical reactive preferred for the industry. Black-Right-Pointing-Pointer Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. Black-Right-Pointing-Pointer An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

  10. Reinforcement of LENRA film by in-situ generated silica produced by sol gel process

    International Nuclear Information System (INIS)

    Mahathir Mohamed; Eda Yuhana Ariffin; Dahlan Mohd; Ibrahim Abdullah

    2008-08-01

    Liquid epoxidised natural rubber acrylate (LENRA) film was reinforced with silica-siloxane structures formed in-situ via sol gel process. Combination of these two components produces organic-inorganic composites. Tetraethylorthosilicate (TEOS) was used as precursor material for silica generation. Sol gel reaction was carried out at different concentrations of TEOS i.e. between 10 and 50 phr. Instrumental analysis was carried out by dynamic mechanical analysis (DMA), thermogravimetry analysis (TGA) and FTIR. It was found that miscibility between organic and inorganic components improved with the presence of silanol groups (Si-OH) and polar solvent i.e. THF, via hydrogen bonding formation between siloxane and LENRA. In this work, the effects of TEOS composition on mechanical properties and interaction that occurs between fillers and matrix have also been studied. It was observed that increasing the concentration of TEOS improved the scratch and stress properties of the film. Morphology study by the scanning electron microscopy (SEM) showed in-situ generated silica particles were homogenous and well dispersed at low concentrations of TEOS. (Author)

  11. Quantum dots/silica/polymer nanocomposite films with high visible light transmission and UV shielding properties.

    Science.gov (United States)

    Mumin, Md Abdul; Xu, William Z; Charpentier, Paul A

    2015-08-07

    The dispersion of light-absorbing inorganic nanomaterials in transparent plastics such as poly(ethylene-co-vinyl acetate) (PEVA) is of enormous current interest in emerging solar materials, including photovoltaic (PV) modules and commercial greenhouse films. Nanocrystalline semiconductor or quantum dots (QDs) have the potential to absorb UV light and selectively emit visible light, which can control plant growth in greenhouses or enhance PV panel efficiencies. This work provides a new and simple approach for loading mesoporous silica-encapsulated QDs into PEVA. Highly luminescent CdS and CdS-ZnS core-shell QDs with 5 nm size were synthesized using a modified facile approach based on pyrolysis of the single-molecule precursors and capping the CdS QDs with a thin layer of ZnS. To make both the bare and core-shell structure QDs more resistant against photochemical reactions, a mesoporous silica layer was grown on the QDs through a reverse microemulsion technique based on hydrophobic interactions. By careful experimental tuning, this encapsulation technique enhanced the quantum yield (∼65%) and photostability compared to the bare QDs. Both the encapsulated bare and core-shell QDs were then melt-mixed with EVA pellets using a mini twin-screw extruder and pressed into thin films with controlled thickness. The results demonstrated for the first time that mesoporous silica not only enhanced the quantum yield and photostability of the QDs but also improved the compatibility and dispersibility of QDs throughout the PEVA films. The novel light selective films show high visible light transmission (∼90%) and decreased UV transmission (∼75%).

  12. Preparation and Characterization of Silica/Polyamide-imide Nanocomposite Thin Films

    Directory of Open Access Journals (Sweden)

    Hwang Jong-Sun

    2010-01-01

    Full Text Available Abstract The functional silica/polyamide-imide composite films were prepared via simple ultrasonic blending, after the silica nanoparticles were modified by cationic surfactant—cetyltrimethyl ammonium bromide (CTAB. The composite films were characterized by scanning electron microscope (SEM, thermo gravimetric analysis (TGA and thermomechanical analysis (TMA. CTAB-modified silica nanoparticles were well dispersed in the polyamide-imide matrix, and the amount of silica nanoparticles to PAI was investigated to be from 2 to 10 wt%. Especially, the coefficients of thermal expansion (CET continuously decreased with the amount of silica particles increasing. The high thermal stability and low coefficient of thermal expansion showed that the nanocomposite films can be widely used in the enamel wire industry.

  13. Physical Characteristics of Chitosan Based Film Modified With Silica and Polyethylene Glycol

    Directory of Open Access Journals (Sweden)

    F. Widhi Mahatmanti

    2014-07-01

    Full Text Available Recently, development of film materials is focused on finding the films with high chemical and physical stabilities. Organic based material such as chitosan produces films with low physical stability, and hence addition of inorganic materials necessary. In this research, the effect of silica and polyethylene glycol (PEG addition on the properties of chitosan based films has been investigated. Precursors used to produce films included chitosan with the deacetylation degree of 83% and sodium silicate solution as the silica source. A simple synthesis in a one-pot process was carried out by mixing 1%(w of chitosan solution in 2%(v/v acetate acid and sodium silicate solution (27% SiO2 in various composition ratios and casting the solution on a glass dish. The tensile strength and percentage of elongation decrease with increasing the silica content. The tensile strength tends to decline with addition of PEG, but the elongation percentage of the film increases. Hydrophilicity of the film decreases with the addition of silica and increases with the addition of PEG. The addition of silica and PEG does not change significantly the morphology of the film and functional groups indicating the domination of physical interaction among active sites in the film components.

  14. Bragg gratings in air-silica structured fibers

    NARCIS (Netherlands)

    Groothoff, N.; Canning, J.; Buckley, E.; Lyttikainen, K.; Zagari, J.

    2003-01-01

    We report on grating writing in air-silica structured optical fibers with pure silica cores by use of two-photon absorption at 193 nm. A decrease in propagation loss with irradiation was observed. The characteristic growth curves were obtained. © 2003 Optical Society of America.

  15. Organized mesoporous silica films as templates for the elaboration of organized nanoparticle networks

    International Nuclear Information System (INIS)

    Gacoin, T; Besson, S; Boilot, J P

    2006-01-01

    Tremendous work achieved in the last 20 years on nanoparticle synthesis has allowed us to study many new physical properties that are found in the nanometre size range. New developments are now expected when considering assemblies of nanoparticles such as 2D or 3D organized arrays. These systems are indeed expected to exhibit original physical properties resulting from particle-particle interactions. Studies in this field are clearly dependent on the elaboration of materials with controlled particle size, organization and interparticle distance. This paper presents a strategy of elaboration that is based on the use of organized mesoporous silica films as templates. These films are made by sol-gel polymerization around surfactant assemblies and further elimination of the surfactant. This provides porous matrices with a pore organization that is the almost perfect replica of the initial micellar structure. The use of such films for the elaboration of organized arrays of nanoparticles is detailed in the case of CdS and Ag particles. The formation of particles inside the pores is achieved through impregnation with precursors that are allowed to diffuse inside the pores. This leads to particles with a size and a spatial arrangement that is directly related to the initial pore structure of the films. This process opens a wide range of investigations due to the relative ease of fabrication over large surfaces and the numerous possibilities offered by the elaboration of porous films with different pore sizes and organizations

  16. Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate

    Directory of Open Access Journals (Sweden)

    Anandakumari Chandrasekharan Sunil Sekhar

    2016-05-01

    Full Text Available Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 103 for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to –NO2 group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies.

  17. SBA-15 mesoporous silica free-standing thin films containing copper ions bounded via propyl phosphonate units - preparation and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Laskowski, Lukasz, E-mail: lukasz.laskowski@kik.pcz.pl [Czestochowa University of Technology, Institute of Computational Intelligence, Unit of Microelectronics and Nanotechnology, Al. Armii Krajowej 36, 42–201 Czestochowa (Poland); Laskowska, Magdalena, E-mail: magdalena.laskowska@onet.pl [H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-342 Krakow, ul. Radzikowskiego 152 (Poland); Jelonkiewicz, Jerzy, E-mail: jerzy.jelonkiewicz@kik.pcz.pl [Czestochowa University of Technology, Institute of Computational Intelligence, Unit of Microelectronics and Nanotechnology, Al. Armii Krajowej 36, 42–201 Czestochowa (Poland); Dulski, Mateusz, E-mail: mateusz.dulski@us.edu.pl [University of Silesia, Faculty of Computer Science and Materials Science, Institute of Materials Science, Silesian Center for Education and Interdisciplinary Research, ul. 75 Pułku Piechoty 1A, 41–500 Chorzów (Poland); Wojtyniak, Marcin, E-mail: marcin.wojtyniak@us.edu.pl [University of Silesia, Institute of Physics, Silesian Center for Education and Interdisciplinary Research, ul. 75 Pułku Piechoty 1A, 41–500 Chorzów (Poland); Fitta, Magdalena, E-mail: magdalena.fitta@ifj.edu.pl [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, 31–342 Krakow, ul. Radzikowskiego 152 (Poland); Balanda, Maria, E-mail: Maria.Balanda@ifj.edu.pl [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, 31–342 Krakow, ul. Radzikowskiego 152 (Poland)

    2016-09-15

    The SBA-15 silica thin films containing copper ions anchored inside channels via propyl phosphonate groups are investigated. Such materials were prepared in the form of thin films, with hexagonally arranged pores, laying rectilinear to the substrate surface. However, in the case of our thin films, their free standing form allowed for additional research possibilities, that are not obtainable for typical thin films on a substrate. The structural properties of the samples were investigated by X-ray reflectometry, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The molecular structure was examined by Raman spectroscopy supported by numerical simulations. Magnetic measurements (SQUID magnetometry and EPR spectroscopy) showed weak antiferromagnetic interactions between active units inside silica channels. Consequently, the pores arrangement was determined and the process of copper ions anchoring by propyl phosphonate groups was verified in unambiguous way. Moreover, the type of interactions between magnetic atoms was determined. - Highlights: • Functionalized free-standing SBA-15 thin films were synthesized for a first time. • Thin films synthesis procedure was described in details. • Structural properties of the films were thoroughly investigated and presented. • Magnetic properties of the novel material was investigated and presented.

  18. Improvement of RVNRL film properties by adding fumed silica and hydroxy apatite

    Directory of Open Access Journals (Sweden)

    Adul Thiangchanya

    2003-01-01

    Full Text Available The effect of adding fumed silica and hydroxy apatite to Radiation Vulcanized Natural Rubber Latex (RVNRL for improving tear strength, aging properties, degradability and water-soluble protein content of rubber films has been investigated. The addition of fumed silica and hydroxy apatite in RVNRL improves tear strength and aging properties of rubber films, whereas tensile strength and degradability of rubber films were unchanged during storage at room temperature. The water-soluble protein content in rubber films was reduced by immobilization of the fumed silica and hydroxy apatite and enhanced by addition of ZnO. This may reduce allergy problems of natural rubber latex products caused by water-soluble protein. The MST of the RVNRL with fumed silica and hydroxy apatite indicated that the latex must be used within two months after mixing because of its stability.

  19. A Robust Fiber Bragg Grating Hydrogen Gas Sensor Using Platinum-Supported Silica Catalyst Film

    OpenAIRE

    Marina Kurohiji; Seiji Ichiriyama; Naoki Yamasaku; Shinji Okazaki; Naoya Kasai; Yusuke Maru; Tadahito Mizutani

    2018-01-01

    A robust fiber Bragg grating (FBG) hydrogen gas sensor for reliable multipoint-leakage monitoring has been developed. The sensing mechanism is based on shifts of center wavelength of the reflection spectra due to temperature change caused by catalytic combustion heat. The sensitive film which consists of platinum-supported silica (Pt/SiO2) catalyst film was obtained using sol-gel method. The precursor solution was composed of hexachloroplatinic acid and commercially available silica precursor...

  20. Persistent superhydrophilicity of sol-gel derived nanoporous silica thin films

    International Nuclear Information System (INIS)

    Ganjoo, S; Azimirad, R; Akhavan, O; Moshfegh, A Z

    2009-01-01

    In this investigation, sol-gel synthesized nanoporous silica thin films, annealed at different temperatures, with long time superhydrophilic property have been studied. Two kinds of sol-gel silica thin films were fabricated by dip-coating of glass substrates in two different solutions; with low and high water. The transparent coated films were dried at 100 deg. C and then annealed in a temperature range of 200-500 deg. C. The average water contact angle of the silica films prepared with low water content and annealed at 300 deg. C measured about 5 deg. for a long time (6 months) without any UV irradiation. Instead, adding water into the sol resulted in silica films with an average water contact angle greater than 60 deg. Atomic force microscopic analysis revealed that the silica films prepared with low water had a rough surface (∼30 nm), while the films prepared with high water had a smoother surface (∼2 nm). Using x-ray photoelectron spectroscopy, we have shown that with a decrease in the surface water on the film, its hydrophilicity increases logarithmically.

  1. Ordered mesoporous silica materials with complicated structures

    KAUST Repository

    Han, Yu; Zhang, Daliang

    2012-01-01

    Periodically ordered mesoporous silicas constitute one of the most important branches of porous materials that are extensively employed in various chemical engineering applications including adsorption, separation and catalysis. This short review

  2. Tailoring of the Nanotexture of Mesoporous Silica Films and their Functionalized Derivatives for Selectively Harvesting Low Molecular Weight Protein

    Science.gov (United States)

    Hu, Ye; Bouamrani, Ali; Tasciotti, Ennio; Li, Li; Liu, Xuewu; Ferrari, Mauro

    2010-01-01

    We present a fast, efficient and reliable system based on mesoporous silica chips to specifically fractionate and enrich the low molecular weight proteome. Mesoporous silica thin films with tunable features at the nanoscale were fabricated using the triblock copolymer template pathway. Using different templates and concentrations in the precursor solution, various pore size distributions, pore structures and connectivity were obtained and applied for selective recovery of low mass proteins. In combination with mass spectrometry and statistic analysis, we demonstrated the correlation between the nanophase characteristics of the mesoporous silica thin films and the specificity and efficacy of low mass proteome harvesting. In addition, to overcome the limitations of the pre-functionalization method in polymer selection, plasma ashing was used for the first time for the treatment of the mesoporous silica surface prior to chemical modification. Surface charge modifications by different functional groups resulted in a selective capture of the low molecular weight proteins from serum sample. In conclusion our study demonstrates that the ability to tune the physico-chemical properties of mesoporous silica surfaces, for a selective enrichment of the low molecular weight proteome from complex biological fluids, has the potential to promote proteomic biomarker discovery. PMID:20014864

  3. Hybrid thin films derived from UV-curable acrylate-modified waterborne polyurethane and monodispersed colloidal silica

    Directory of Open Access Journals (Sweden)

    C. H. Yang

    2012-01-01

    Full Text Available Hybrid thin films containing nano-sized inorganic domains were synthesized from UV-curable acrylate-modified waterborne polyurethane (WPU-AC and monodispersed colloidal silica with coupling agent. The coupling agent, 3-(trimethoxysilylpropyl methacrylate (MSMA, was bonded onto colloidal silica first, and then mixed with WPU-AC to form a precursor solution. This precursor was spin coated, dried and UV-cured to generate the hybrid films. The silica content in the hybrid thin films was varied from 0 to 30 wt%. Experimental results showed the aggregation of silica particles in the hybrid films. Thus, the silica domain in the hybrid films was varied from 30 to 50 nm by the different ratios of MSMAsilica to WPU-AC. The prepared hybrid films from the crosslinked WPU-AC/MSMA-silica showed much better thermal stability and mechanical properties than pure WPU-AC.

  4. Supramolecular structures on silica surfaces and their adsorptive properties.

    Science.gov (United States)

    Belyakov, Vladimir N; Belyakova, Lyudmila A; Varvarin, Anatoly M; Khora, Olexandra V; Vasilyuk, Sergei L; Kazdobin, Konstantin A; Maltseva, Tetyana V; Kotvitskyy, Alexey G; Danil de Namor, Angela F

    2005-05-01

    The study of adsorptive and chemical immobilization of beta-cyclodextrin on a surface of hydroxylated silicas with various porous structure is described. Using IR spectroscopy, thermal gravimetrical analysis with a programmed heating, and chemical analysis of the silica surface, it is shown that the process of adsorption-desorption of beta-cyclodextrin depends on the porous structure of the silica. The reaction of esterification was used for chemical grafting of beta-cyclodextrin on the surface of hydroxylated silicas. Hydrolytic stability of silicas chemically modified by beta-cyclodextrin apparently is explained by simultaneous formation of chemical and hydrogen bonds between surface silanol groups and hydroxyl groups of beta-cyclodextrin. The uptake of the cations Cu(II), Cd(II), and Pb(II) and the anions Cr(VI) and As(V) by silicas modified with beta-cyclodextrin is investigated as a function of equilibrium ion concentrations. The increase of ion uptake and selectivity of ion extraction in comparison with starting silicas is established. It is due to the formation of surface inclusion complexes of the "host-guest" type in which one molecule of beta-cyclodextrin interacts simultaneously with several ions.

  5. Preparing hydrophobic nanocellulose-silica film by a facile one-pot method.

    Science.gov (United States)

    Le, Duy; Kongparakul, Suwadee; Samart, Chanatip; Phanthong, Patchiya; Karnjanakom, Surachai; Abudula, Abuliti; Guan, Guoqing

    2016-11-20

    Hydrophobic nanocellulose-silica film was successfully prepared by a facile one-pot method using tetraethoxysilane (TEOS) and dodecyl triethoxylsilane (DTES). Morphological characterization of the hydrophobic nanocellulose-silica (NC-SiO2-DTES) film showed well self-assembled DTES modified silica spherical nanoparticles with the particle sizes in the range of 88-126nm over the nanocellulose film. The hydrophobicity of the NC-SiO2-DTES film was achieved owing to the improvement of roughness of the nanocellulose film by coating dodecyl- terminated silica nanoparticles. An increase in DTES loading amount and reaction time increased the hydrophobicity of the film, and the optimum condition for NC-SiO2-DTES film preparation was achieved at DTES/TEOS molar ratio of 2.0 for 8h reaction time. Besides, the NC-SiO2-DTES film performed superoleophilic property with octane and hexadecane contact angles of 0°. It also showed an excellent hydrophobic property over all pH values ranged from 1 to 14. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Mesoporous silica films as catalyst support for microstructured reactors: preparation and characterization

    NARCIS (Netherlands)

    Muraza, O.; Kooyman, P.J.; Lafont, U.; Albouy, P.A.; Khimyak, T.; Rebrov, E.V.; Croon, de M.H.J.M.; Schouten, J.C.

    2008-01-01

    Mesoporous silica thin films with hexagonal and cubic mesostructure have been deposited by the evaporation induced self-assembly assisted sol–gel route on microchannels etched in a Pyrex® 7740 borosilicate glass substrate. Prior to the synthesis, a 50 nm TiO2 film has been deposited on the substrate

  7. Photochemical oxygen reduction by zinc phthalocyanine and silver/gold nanoparticle incorporated silica thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Manas; Ganesan, Vellaichamy, E-mail: velganesh@yahoo.com; Azad, Uday Pratap

    2012-12-15

    Silver or gold nanoparticles are synthesized using a borohydride reduction method and are anchored simultaneously into/onto the mercaptopropyl functionalized silica. Later, zinc phthalocyanine is adsorbed onto the above materials. Thin films of these materials are prepared by coating an aqueous colloidal suspension of the respective material onto glass plates. Visible light irradiation of these films in oxygen saturated, stirred aqueous solutions effectively reduces oxygen to hydrogen peroxide. The photocatalytic reduction of oxygen is explained on the basis of the semiconducting properties of the silica films. The back electron transfer reaction is largely prevented by means of a sacrificial electron donor, triethanolamine. - Highlights: Black-Right-Pointing-Pointer Zinc phthalocyanine adsorbed silica materials were prepared. Black-Right-Pointing-Pointer Thin films of these materials photocatalytically reduce oxygen. Black-Right-Pointing-Pointer The photocatalysis is explained based on semiconductor properties of the materials. Black-Right-Pointing-Pointer Metal nanoparticles increase the photocatalytic efficiency of the materials.

  8. Structure and dynamics of a silica melt in neutral confinement

    Science.gov (United States)

    Geske, Julian; Drossel, Barbara; Vogel, Michael

    2017-04-01

    We analyze the effects of spatial confinement on viscous silica using molecular dynamics simulations. For this purpose, we prepare a silica melt in a cylindrical pore, which is produced by pinning appropriate fractions of silicon and oxygen atoms in a bulk system after an equilibration period. In this way, the structure of the confined silica melt remains unaffected, while the confinement has a strong impact on the dynamics. We find that the structural relaxation of viscous silica is slowed down according to a double exponential law when approaching the pore wall. Moreover, we observe that static density correlations exist in the vicinity of the pore wall. Based on these effects, we determine dynamical and structural length scales of the silica melt. Both length scales show a similar increase upon cooling, with values on the order of the next-neighbor distances in the studied temperature range. Interestingly, we find no evidence that the growth of the length scales is affected by a fragile-to-strong transition of the silica melt. This observation casts serious doubts on the relevance of these length scales for the structural relaxation, at least for the studied glass former.

  9. Sol-gel-derived mesoporous silica films with low dielectric constants

    Energy Technology Data Exchange (ETDEWEB)

    Seraji, S.; Wu, Yun; Forbess, M.; Limmer, S.J.; Chou, T.; Cao, Guozhong [Washington Univ., Seattle, WA (United States). Dept. of Materials Science and Engineering

    2000-11-16

    Mesoporous silica films with low dielectric constants and possibly closed pores have been achieved with a multiple step sol-gel processing technique. Crack-free films with approximately 50% porosity and 0.9 {mu}m thicknesses were obtained, a tape-test revealing good adhesion between films and substrates or metal electrodes. Dielectric constants remained virtually unchanged after aging at room temperature at 56% humidity over 6 days. (orig.)

  10. Synthesis of Novel Mesoporous Silica Materials with Hierarchical Pore Structures

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Suk Bon; Choi, Wang Kyu; Choi, Byung Seon; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Porous materials with various pore sizes in the range of micropore (< 2 nm), mesopore (2-50 nm), and macropore (> 50 nm) are attractive due to their many emerging applications such as catalysts, separation systems, and low dielectric constant materials. The discovery of new M41S mesoporous silica families with pore sizes larger than 2 nm in diameter in 1992 extended the applications into much wider pore ranges, bringing in a new prosperous era in porous material research. The synthesis of these silica materials has been mainly accomplished through a self-assembly between surfactant molecules and inorganic species under various pH conditions. Recently, core-shell nanoparticles with a silica core and mesoporous shell under basic conditions were synthesized using the silica nanoparticles as a core, and a silica precursor (TEOS) and cationic surfactant (CTABr) as a material for the formation of the mesoporous shell. The resultant materials were very monodispersive in size and showed a narrow pore size distribution in the range of ca 2-3 nm in diameter, depending on the alkyl-chain length of the surfactants used. In this work, the mesoporous shell coated-fumed silicas (denoted as MS M-5s) were synthesized by using fumed silica instead of the silica nanoparticle as a core based on previous reports. Also, the structural properties of the MS M-5s such as the specific surface area and pore volume were easily controlled by varying the amount of the silica precursor and surfactant. The resultant materials exhibited a BET surface area of ca 279-446 m{sup 2}/g and total pore volume of ca 0.64-0.74 cm{sup 3}/g and showed a narrow pore size distribution (PSD) due to the removal of the organic surfactant molecules

  11. Relaxation of excited surface states of thin Ge-implanted silica films probed by OSEE spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zatsepin, A.F., E-mail: a.f.zatsepin@urfu.ru [Ural Federal University, Mira Street 19, 620002 Ekaterinburg (Russian Federation); Buntov, E.A.; Mikhailovich, A.P.; Slesarev, A.I. [Ural Federal University, Mira Street 19, 620002 Ekaterinburg (Russian Federation); Schmidt, B. [Research Center Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, P.O. Box 510119, D-01314 Dresden (Germany); Czarnowski, A. von; Fitting, Hans-Joachim [Institute of Physics, University of Rostock, Universitätsplatz 3, D-18051 Rostock (Germany)

    2016-01-15

    As an example of thin silica films, 30 nm SiO{sub 2}–Si heterostructures implanted with Ge{sup +} ions (10{sup 16} cm{sup −2} fluence) and rapid thermally annealed (RTA) at 950 °C are studied by means of optically stimulated electron emission (OSEE) in the spectral region of optical transparency for bulk silica. Quartz glass samples were used as references. Experimental data revealed a strong dependence between electron emission spectral features and RTA annealing time. The spectral contributions of both surface band tail states and interband transitions were clearly distinguished. The application of emission Urbach rule as well as Kane and Pässler equations allowed to analyze the OSEE spectra at different optical excitation energy ranges and to retrieve the important microstructural and energy parameters. The observed correlations between parameter values of Urbach- and Kane-related models suggest the implantation-induced conversion of both the vibrational subsystem and energy band of surface and interface electronic states. - Highlights: • Peculiarities of electron emission from excited surface states of SiO{sub 2}:Ge structures are studied. • Spectral contributions of surface band tails and interband transitions are distinguished. • Urbach and Kane models allow to examine photo-thermal emission mechanism. • Surface energy gap and structural disorder parameters are determined.

  12. Preparation and Properties of Nano Dy/TiO2 Films Supported on High Silica Fiber

    Directory of Open Access Journals (Sweden)

    HUANG Feng-ping

    2017-07-01

    Full Text Available In order to improve the photocatalytic degradation performance and stability of nano TiO2, Dy doped TiO2 supported on high silica glass fiber was prepared by microwave-sol method combined with dip-coating method. The samples were analyzed by XRD,SEM,PL,EDS,XPS and other equipments for phase composition of films,surface topography, surface elements and the stability of films. And the effects of pretreatment solution and coating method on the high-silica fiber film were investigated.In addition, the photocatalytic performance of the sample has been investigated by degrading methylene blue. The results show that the catalytic stability of Dy doping TiO2 nanofilms supported on high silica glass fiber can be improved and the degradation of methyl orange can reach 94% in 30min after 5 times of coating treatment.

  13. Biodegradable Starch/Copolyesters Film Reinforced with Silica Nanoparticles: Preparation and Characterization

    Science.gov (United States)

    Lima, Roberta A.; Oliveira, Rene R.; Wataya, Célio H.; Moura, Esperidiana A. B.

    Biodegradable starch/copolyesters/silica nanocomposite films were prepared by melt extrusion, using a twin screw extruder machine and blown extrusion process. The influence of the silica nanoparticle addition on mechanical and thermal properties of nanocomposite films was investigated by tensile tests; X-rays diffraction (XRD), differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM) analysis and the correlation between properties was discussed. The results showed that incorporation of 2 % (wt %) of SiO2 nanoparticle in the blend matrix of PBAT/Starch, resulted in a gain of mechanical properties of blend.

  14. High-coercivity FePt nanoparticle assemblies embedded in silica thin films

    International Nuclear Information System (INIS)

    Yan, Q; Purkayastha, A; Singh, A P; Li, H; Ramanath, G; Li, A; Ramanujan, R V

    2009-01-01

    The ability to process assemblies using thin film techniques in a scalable fashion would be a key to transmuting the assemblies into manufacturable devices. Here, we embed FePt nanoparticle assemblies into a silica thin film by sol-gel processing. Annealing the thin film composite at 650 deg. C transforms the chemically disordered fcc FePt phase into the fct phase, yielding magnetic coercivity values H c >630 mT. The positional order of the particles is retained due to the protection offered by the silica host. Such films with assemblies of high-coercivity magnetic particles are attractive for realizing new types of ultra-high-density data storage devices and magneto-composites.

  15. Secondary electron emission yield on poled silica based thick films

    DEFF Research Database (Denmark)

    Braga, D.; Poumellec, B.; Cannas, V.

    2004-01-01

    Studies on the distribution of the electric field produced by a thermal poling process in a layer of Ge-doped silica on silicon substrate, by using secondary electron emission yield (SEEY) measurements () are presented. Comparing 0 between poled and unpoled areas, the SEEY at the origin of electr...

  16. Low temperature mechanical dissipation of an ion-beam sputtered silica film

    International Nuclear Information System (INIS)

    Martin, I W; Craig, K; Bassiri, R; Hough, J; Robie, R; Rowan, S; Nawrodt, R; Schwarz, C; Harry, G; Penn, S; Reid, S

    2014-01-01

    Thermal noise arising from mechanical dissipation in oxide mirror coatings is an important limit to the sensitivity of future gravitational wave detectors, optical atomic clocks and other precision measurement systems. Here, we present measurements of the temperature dependence of the mechanical dissipation of an ion-beam sputtered silica film between 10 and 300 K. A dissipation peak was observed at 20 K and the low temperature dissipation was found to have significantly different characteristics than observed for bulk silica and silica films deposited by alternative techniques. These results are important for better understanding the underlying mechanisms of mechanical dissipation, and thus thermal noise, in the most commonly-used reflective coatings for precision measurements. (paper)

  17. Biomimetic Cationic Nanoparticles Based on Silica: Optimizing Bilayer Deposition from Lipid Films

    Directory of Open Access Journals (Sweden)

    Rodrigo T. Ribeiro

    2017-10-01

    Full Text Available The optimization of bilayer coverage on particles is important for a variety of biomedical applications, such as drug, vaccine, and genetic material delivery. This work aims at optimizing the deposition of cationic bilayers on silica over a range of experimental conditions for the intervening medium and two different assemblies for the cationic lipid, namely, lipid films or pre-formed lipid bilayer fragments. The lipid adsorption on silica in situ over a range of added lipid concentrations was determined from elemental analysis of carbon, hydrogen, and nitrogen and related to the colloidal stability, sizing, zeta potential, and polydispersity of the silica/lipid nanoparticles. Superior bilayer deposition took place from lipid films, whereas adsorption from pre-formed bilayer fragments yielded limiting adsorption below the levels expected for bilayer adsorption.

  18. Defect prevention in silica thin films synthesized using AP-PECVD for flexible electronic encapsulation

    NARCIS (Netherlands)

    Elam, F.M.; Starostin, S.A.; Meshkova, A.S.; Van Der Velden-Schuermans, B.C.A.M.; Van De Sanden, M.C.M.; De Vries, H.W.

    2017-01-01

    Industrially and commercially relevant roll-to-roll atmospheric pressure-plasma enhanced chemical vapour deposition was used to synthesize smooth, 80 nm silica-like bilayer thin films comprising a dense 'barrier layer' and comparatively porous 'buffer layer' onto a flexible polyethylene 2,6

  19. Phosphorus-doped thin silica films characterized by magic-angle spinning nuclear magnetic resonance spectroscopy

    DEFF Research Database (Denmark)

    Jacobsen, H.J.; Skibsted, J.; Kristensen, Martin

    2001-01-01

    Magic-angle spinning nuclear magnetic resonance spectra of 31P and 29Si have been achieved for a thin silica film doped with only 1.8% 31P and deposited by plasma enhanced chemical vapor deposition on a pure silicon wafer. The observation of a symmetric 31P chemical shift tensor is consistent...

  20. Spin-on nanostructured silicon-silica film displaying room-temperature nanosecond lifetime photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Y.; Hatton, B.; Miguez, H.; Coombs, N.; Fournier-Bidoz, S.; Ozin, G.A. [Materials Chemistry Research Group, Department of Chemistry, Lash Miller Chemical Laboratories, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 (Canada); Grey, J.K.; Beaulac, R.; Reber, C. [Department of Chemistry, University of Montreal, Montreal, Quebec H3C 3J7 (Canada)

    2003-04-17

    A yellow transparent mesoporous silica film has been achieved by the incorporation of silicon nanoclusters into its channels. The resulting nanocomposite - fabricated using a combination of evaporation induced self- assembly and chemical vapor deposition - emits light brightly at visible wavelengths and has nanosecond radiative lifetimes at room temperature when excited by ultraviolet light (see Figure). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  1. Defect prevention in silica thin films synthesized using AP-PECVD for flexible electronic encapsulation

    NARCIS (Netherlands)

    Elam, F. M.; Starostin, S. A.; Meshkova, A. S.; van der Velden, B. C. A. M.; van de Sanden, M. C. M.; de Vries, H. W.

    2017-01-01

    Industrially and commercially relevant roll-to-roll atmospheric pressure-plasma enhanced chemical vapour deposition was used to synthesize smooth, 80 nm silica-like bilayer thin films comprising a dense ‘barrier layer’ and comparatively porous ‘buffer layer’ onto a flexible polyethylene 2,6

  2. Highly Aminated Mesoporous Silica Nanoparticles with Cubic Pore Structure

    KAUST Repository

    Suteewong, Teeraporn

    2011-01-19

    Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy.

  3. Highly Aminated Mesoporous Silica Nanoparticles with Cubic Pore Structure

    KAUST Repository

    Suteewong, Teeraporn; Sai, Hiroaki; Cohen, Roy; Wang, Suntao; Bradbury, Michelle; Baird, Barbara; Gruner, Sol M.; Wiesner, Ulrich

    2011-01-01

    Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy.

  4. Easy approach to assembling a biomimetic color film with tunable structural colors.

    Science.gov (United States)

    Wang, Wentao; Tang, Bingtao; Ma, Wei; Zhang, Jian; Ju, Benzhi; Zhang, Shufen

    2015-06-01

    The self-assembly of silica microspheres into a close-packed array is a simple method of fabricating three-dimensional photonic crystal structural color films. However, the color is very dull because of the interferences of scattering and background light. In this study, we added a small quantity of surface-modified carbon black (CB) to the system of colloidal silica in n-propanol. The use of n-propanol as a dispersant is beneficial to the rapid development of photonic crystal films during the process of dip-coating. The doping of CB into silica microspheres can absorb background and scattering light, resulting in vivid structural colors.

  5. Low molecular weight protein enrichment on mesoporous silica thin films for biomarker discovery.

    Science.gov (United States)

    Fan, Jia; Gallagher, James W; Wu, Hung-Jen; Landry, Matthew G; Sakamoto, Jason; Ferrari, Mauro; Hu, Ye

    2012-04-17

    The identification of circulating biomarkers holds great potential for non invasive approaches in early diagnosis and prognosis, as well as for the monitoring of therapeutic efficiency.(1-3) The circulating low molecular weight proteome (LMWP) composed of small proteins shed from tissues and cells or peptide fragments derived from the proteolytic degradation of larger proteins, has been associated with the pathological condition in patients and likely reflects the state of disease.(4,5) Despite these potential clinical applications, the use of Mass Spectrometry (MS) to profile the LMWP from biological fluids has proven to be very challenging due to the large dynamic range of protein and peptide concentrations in serum.(6) Without sample pre-treatment, some of the more highly abundant proteins obscure the detection of low-abundance species in serum/plasma. Current proteomic-based approaches, such as two-dimensional polyacrylamide gel-electrophoresis (2D-PAGE) and shotgun proteomics methods are labor-intensive, low throughput and offer limited suitability for clinical applications.(7-9) Therefore, a more effective strategy is needed to isolate LMWP from blood and allow the high throughput screening of clinical samples. Here, we present a fast, efficient and reliable multi-fractionation system based on mesoporous silica chips to specifically target and enrich LMWP.(10,11) Mesoporous silica (MPS) thin films with tunable features at the nanoscale were fabricated using the triblock copolymer template pathway. Using different polymer templates and polymer concentrations in the precursor solution, various pore size distributions, pore structures, connectivity and surface properties were determined and applied for selective recovery of low mass proteins. The selective parsing of the enriched peptides into different subclasses according to their physicochemical properties will enhance the efficiency of recovery and detection of low abundance species. In combination with mass

  6. Silica promoted self-assembled mesoporous aluminas. Impact of the silica precursor on the structural, textural and acidic properties

    NARCIS (Netherlands)

    Perez, Lidia Lopez; Zarubina, Valeriya; Mayoral, Alvaro; Melian-Cabrera, Ignacio

    2015-01-01

    This paper investigates the effect of silica addition on the structural, textural and acidic properties of an evaporation induced self-assembled (EISA) mesoporous alumina. Two silica addition protocols were applied while maintaining the EISA synthesis route. The first route is based on the addition

  7. Reaction kinetics for preparation of silica film with Stoeber method

    International Nuclear Information System (INIS)

    Shang Mengying; Jiang Xiaodong; Liu Miao; Luo Xuan; Tang Yongjian; Cao Linhong

    2013-01-01

    A new formula was proposed to investigate the relationship between reaction time and tetraethylorthosilicate (TEOS) conversion rate for preparation of silica sol with Stöber method, by studying the reaction kinetics of TEOS hydrolytic process. An appropriate conversion rate was then determined and used to calculate the theoretical optimal reaction time. Meanwhile, silica sols were prepared by sol-gel process using TEOS as precursor and ammonia as catalyst. It was found that the reaction time decreases with an increasing amount of ammonia and water. The values of experimental optimal reaction time were obtained, and agree with the theoretical results (the errors are within 5%), which shows good applicability of our formula. (authors)

  8. Nanotexture Optimization by Oxygen Plasma of Mesoporous Silica Thin Film for Enrichment of Low Molecular Weight Peptides Captured from Human Serum

    Science.gov (United States)

    Hu, Ye; Peng, Yang; Brousseau, Louis; Bouamrani, Ali; Liu, Xuewu; Ferrari, Mauro

    2010-01-01

    This study investigated the optimization of mesoporous silica thin films by nanotexturing using oxygen plasma versus thermal oxidation. Calcination in oxygen plasma provides superior control over pore formation with regard to the pore surface and higher fidelity to the structure of the polymer template. The resulting porous film offers an ideal substrate for the selective partitioning of peptides from complex mixtures. The improved chemico-physical characteristics of porous thin films (pore size distribution, nanostructure, surface properties and pore connectivity) were systematically characterized with XRD, Ellipsometry, FTIR, TEM and N2 adsorption/desorption. The enrichment of low molecular weight proteins captured from human serum on mesoporous silica thin films fabricated by both methodologies were investigated by comparison of their MALDI-TOF MS profiles. This novel on-chip fractionation technology offers advantages in recovering the low molecular weight peptides from human serum, which has been recognized as an informative resource for early diagnosis of cancer and other diseases. PMID:21179395

  9. Superhydrophobic transparent films from silica powder: Comparison of fabrication methods

    KAUST Repository

    Liu, Li-Der; Lin, Chao-Sung; Tikekar, Mukul; Chen, Ping-Hei

    2011-01-01

    The lotus leaf is known for its self-clean, superhydrophobic surface, which displays a hierarchical structure covered with a thin wax-like material. In this study, three fabrication techniques, using silicon dioxide particles to create surface roughness followed by a surface modification with a film of polydimethylsiloxane, were applied on a transparent glass substrate. The fabrication techniques differed mainly on the deposition of silicon dioxide particles, which included organic, inorganic, and physical methods. Each technique was used to coat three samples of varying particle load. The surface of each sample was evaluated with contact angle goniometer and optical spectrometer. Results confirmed the inverse relationships between contact angle and optical transmissivity independent of fabrication techniques. Microstructural morphologies also suggested the advantage of physical deposition over chemical methods. In summary, the direct sintering method proved outstanding for its contact angle vs transmissivity efficiency, and capable of generating a contact angle as high as 174°. © 2011 Elsevier B.V. All rights reserved.

  10. Superhydrophobic transparent films from silica powder: Comparison of fabrication methods

    KAUST Repository

    Liu, Li-Der

    2011-07-01

    The lotus leaf is known for its self-clean, superhydrophobic surface, which displays a hierarchical structure covered with a thin wax-like material. In this study, three fabrication techniques, using silicon dioxide particles to create surface roughness followed by a surface modification with a film of polydimethylsiloxane, were applied on a transparent glass substrate. The fabrication techniques differed mainly on the deposition of silicon dioxide particles, which included organic, inorganic, and physical methods. Each technique was used to coat three samples of varying particle load. The surface of each sample was evaluated with contact angle goniometer and optical spectrometer. Results confirmed the inverse relationships between contact angle and optical transmissivity independent of fabrication techniques. Microstructural morphologies also suggested the advantage of physical deposition over chemical methods. In summary, the direct sintering method proved outstanding for its contact angle vs transmissivity efficiency, and capable of generating a contact angle as high as 174°. © 2011 Elsevier B.V. All rights reserved.

  11. Positron and positronium annihilation in silica-based thin films studied by a pulsed positron beam

    International Nuclear Information System (INIS)

    Suzuki, R.; Ohdaira, T.; Kobayashi, Y.; Ito, K.; Shioya, Y.; Ishimaru, T.

    2003-01-01

    Positron and positronium annihilation in silica-based thin films has been investigated by means of measurement techniques with a monoenergetic pulsed positron beam. The age-momentum correlation study revealed that positron annihilation in thermally grown SiO 2 is basically the same as that in bulk amorphous SiO 2 while o-Ps in the PECVD grown SiCOH film predominantly annihilate with electrons of C and H at the microvoid surfaces. We also discuss time-dependent three-gamma annihilation in porous low-k films by two-dimensional positron annihilation lifetime spectroscopy

  12. Structural changes in femtosecond laser modified regions inside fused silica

    International Nuclear Information System (INIS)

    Juodkazis, Saulius; Kohara, Shinji; Ohishi, Yasuo; Hirao, Norihisa; Vailionis, Arturas; Mizeikis, Vygantas; Saito, Akira; Rode, Andrei

    2010-01-01

    Structural characterization of photomodified microvolumes formed by tightly focused femtosecond laser pulses inside silica glass was carried out using synchrotron x-ray diffraction. The observed distinct separation between the O–O and Si–Si pair correlation peaks can be interpreted as a phase separation induced by microexplosions at the focal volume. The mechanisms of structural transitions induced by femtosecond laser pulses inside dielectrics are discussed

  13. Incorporation of Nanohybrid Films of Silica into Recycled Polystyrene Matrix

    Directory of Open Access Journals (Sweden)

    Genoveva Hernández-Padrón

    2015-01-01

    Full Text Available An alternative for the reutilization of polystyrene waste containers consisting in creating a hybrid material made of SiO2 nanoparticles embedded in a matrix of recycled polystyrene (PSR has been developed. Recycled polystyrene functionalized (PSRF was used to influence the morphological and antifog properties by the sol-gel synthesis of nanohybrid silica. To this end, silica nanoparticles were produced from alkoxide precursors in the presence of recycled polystyrene. The functionalization of this polymeric matrix was with the purpose of uniting in situ carboxyl and silanol groups during the sol-gel process. In this way, opaque or transparent solid substrates can be obtained, with each of these endowed with optical conditions that depend on the amount of reactants employed to prepare each nanohybrid specimen. The nanohybrids were labelled as SiO2/PSR (HPSR and SiO2/PSRF (HPSRF and their properties were then compared to those of commercial polystyrene (PS. All the prepared samples were used for coating glass substrates. The hydrophobicity of the resultant coatings was determined through contact angle measurement. The nanohybrid materials were characterized by FT-IR and 1H-NMR techniques. Additionally, TGA and SEM were employed to determine their thermal and textural properties.

  14. High-quality substrate for fluorescence enhancement using agarose-coated silica opal film.

    Science.gov (United States)

    Xu, Ming; Li, Juan; Sun, Liguo; Zhao, Yuanjin; Xie, Zhuoying; Lv, Linli; Zhao, Xiangwei; Xiao, Pengfeng; Hu, Jing; Lv, Mei; Gu, Zhongze

    2010-08-01

    To improve the sensitivity of fluorescence detection in biochip, a new kind of substrates was developed by agarose coating on silica opal film. In this study, silica opal film was fabricated on glass substrate using the vertical deposition technique. It can provide stronger fluorescence signals and thus improve the detection sensitivity. After coating with agarose, the hybrid film could provide a 3D support for immobilizing sample. Comparing with agarose-coated glass substrate, the agarose-coated opal substrates could selectively enhance particular fluorescence signals with high sensitivity when the stop band of the silica opal film in the agarose-coated opal substrate overlapped the fluorescence emission wavelength. A DNA hybridization experiment demonstrated that fluorescence intensity of special type of agarose-coated opal substrates was about four times that of agarose-coated glass substrate. These results indicate that the optimized agarose-coated opal substrate can be used for improving the sensitivity of fluorescence detection with high quality and selectivity.

  15. A Robust Fiber Bragg Grating Hydrogen Gas Sensor Using Platinum-Supported Silica Catalyst Film

    Directory of Open Access Journals (Sweden)

    Marina Kurohiji

    2018-01-01

    Full Text Available A robust fiber Bragg grating (FBG hydrogen gas sensor for reliable multipoint-leakage monitoring has been developed. The sensing mechanism is based on shifts of center wavelength of the reflection spectra due to temperature change caused by catalytic combustion heat. The sensitive film which consists of platinum-supported silica (Pt/SiO2 catalyst film was obtained using sol-gel method. The precursor solution was composed of hexachloroplatinic acid and commercially available silica precursor solution. The atom ratio of Si : Pt was fixed at 13 : 1. A small amount of this solution was dropped on the substrate and dried at room temperature. After that, the film was calcined at 500°C in air. These procedures were repeated and therefore thick hydrogen-sensitive films were obtained. The catalytic film obtained by 20-time coating on quartz glass substrate showed a temperature change 75 K upon exposure to 3 vol.% H2. For realizing robust sensor device, this catalytic film was deposited and FBG portion was directly fixed on titanium substrate. The sensor device showed good performances enough to detect hydrogen gas in the concentration range below lower explosion limit at room temperature. The enhancement of the sensitivity was attributed to not only catalytic combustion heat but also related thermal strain.

  16. TiO2 and SiC nanostructured films, organized CNT structures

    Indian Academy of Sciences (India)

    sized nanostructured TiO2 films through hydrolysis of titanium tetra-isopropoxide. (TTIP) [9 ... structured TiO2 as a photocatalyst is as follows [15]:. TiO2(ns) ... The deposited films were easily detached from the silica tube and subjected to. SEM.

  17. Photonic bandgap structure of 3-D fcc silica nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Y. K.; Ha, N. Y.; Hwang, Ji Soo; Chang, H. J.; Wu, J. W. [Dept. of Physics, Ewha Womans University, Seoul (Korea, Republic of)

    2002-07-01

    Photonic crystal is an artificial optical material with a periodic dielectric potential, hence exhibiting a bandgap for a propagating electromagnetic wave. We fabricated crystal possessing 3-D fcc opal structure from silica nanospheres. The crystals are self-assembled on a flat glass by evaporating the solvent in the nanosphere suspension at the room temperature. The suspension consists of silica nanospheres with a diameter of 200 nm. The microscopic arrangement of nanospheres is identified by a scanning electron microscope, the resulting structure being fcc.Transmission spectrum of the fabricated photonic crystal in the visible and near-infrared regions is measured at different incident angles to find the distinct Bragg peaks, analysis of which further confirmed the fcc structure of the photonic crystal. From the optical microscopic image, we find that the opal domain varies from 30 μm to 125 μm in size. In order to relate the observed Bragg peaks with the microscopic arrangement of silica nanospheres, we introduced the scalar wave approximation, where the electric field in the medium is treated as a scalar rather than a vector quantity. It is found that the theoretical prediction of the position of bandgap is in a good agreement with the experimental measurement.

  18. Photonic bandgap structure of 3-D fcc silica nanospheres

    International Nuclear Information System (INIS)

    Woo, Y. K.; Ha, N. Y.; Hwang, Ji Soo; Chang, H. J.; Wu, J. W.

    2002-01-01

    Photonic crystal is an artificial optical material with a periodic dielectric potential, hence exhibiting a bandgap for a propagating electromagnetic wave. We fabricated crystal possessing 3-D fcc opal structure from silica nanospheres. The crystals are self-assembled on a flat glass by evaporating the solvent in the nanosphere suspension at the room temperature. The suspension consists of silica nanospheres with a diameter of 200 nm. The microscopic arrangement of nanospheres is identified by a scanning electron microscope, the resulting structure being fcc.Transmission spectrum of the fabricated photonic crystal in the visible and near-infrared regions is measured at different incident angles to find the distinct Bragg peaks, analysis of which further confirmed the fcc structure of the photonic crystal. From the optical microscopic image, we find that the opal domain varies from 30 μm to 125 μm in size. In order to relate the observed Bragg peaks with the microscopic arrangement of silica nanospheres, we introduced the scalar wave approximation, where the electric field in the medium is treated as a scalar rather than a vector quantity. It is found that the theoretical prediction of the position of bandgap is in a good agreement with the experimental measurement.

  19. Superconducting Electronic Film Structures

    Science.gov (United States)

    1991-02-14

    Segmuller, A., Cooper, E.I., Chisholm, M.F., Gupta, A. Shinde, S., and Laibowitz, R.B. Lanthanum gallate substrates for epitaxial high-T superconducting thin...M. F. Chisholm, A. Gupta, S. Shinde, and R. B. Laibowitz, " Lanthanum Gallate Substrates for Epitaxial High-T c Superconducting Thin Films," Appl...G. Forrester and J. Talvacchio, " Lanthanum Copper Oxide Buffer Layers for Growth of High-T c Superconductor Films," Disclosure No. RDS 90-065, filed

  20. Electrochemical lithium migration to mitigate alkali-silica reaction in existing concrete structures

    NARCIS (Netherlands)

    Silva De Souza, L.M.

    2016-01-01

    Alkali-silica reaction (ASR) is a deterioration process that affects the durability of concrete structures worldwide. During the reaction, hydroxyl and alkali ions present in the pore solution react with reactive silica from the aggregate, forming a hygroscopic ASR gel. Alternatively, the silica

  1. Structural and optical studies of nano-structure silica gel doped with different rare earth elements, prepared by two different sol -gel techniques

    International Nuclear Information System (INIS)

    Battisha, I.K.; El Beyally, A.; Seliman, S.I.; El Nahrawi, A.S.

    2005-01-01

    Structural and optical characteristics of pure silica gel (silica-xerogel, SiO 2 ) and doped with different concentrations ranging from 1 up to 6% of some rare earth (REEs) ions such as, praseodymium Pr +3 ,and Europium Eu +3 , Erbium Er +3 and Holmium Ho +3 , ions, in the form of thin film and monolith materials were prepared by sol - gel technique, Using tetra-ethoxysilane as precursor materials, which are of particular interest for sol-gel integrated optics applications. Some structural and optical features of sol-gel derived monolith and thin films are analyzed and compared, namely the structure of nano-particle monolith and thin film silica-gel samples, based on X-ray diffraction (XRD). The types of structural information obtainable are compared in detail. It is show that the XRD spectra of a-cristobalite are obtained for the two type materials and even by doping with the four REEs ions. Optical measurements of monolith and thin films were also studied and compared, the normal transmission and specular reflection were measured. The refractive index were calculated and discussed

  2. Voltammetric Determination of Lead (II) and Cadmium (II) Using a Bismuth Film Electrode Modified with Mesoporous Silica Nanoparticles

    International Nuclear Information System (INIS)

    Yang, Die; Wang, Liang; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravi

    2014-01-01

    A new chemically modified glassy carbon electrode based on bismuth film coated mesoporous silica nanoparticles was developed and evaluated for reliable quantification of trace Pb 2+ and Cd 2+ by anodic stripping square wave voltammetry in natural water samples. Compared with conventional bismuth film electrodes or bismuth nanoparticles modified electrodes, this electrode exhibited significantly improved sensitivity and stability for Pb 2+ and Cd 2+ detection. The key experimental parameters related to the fabrication of the electrode and the voltammetric measurements were optimized on the basis of the stripping signals, where the peak currents increased linearly with the metal concentrations in a range of 2-150 μg L −1 with a detect limit of 0.2 μg L −1 for Pb 2+ , and 0.6 μg L −1 for Cd 2+ for 120s deposition. Good reproducibility was achieved on both single and equally prepared electrodes. In addition, scanning electron microscopy reveals that fibril-like bismuth structures were formed on silica nanoparticles, which could be responsible for the improved voltammetric performance due to the enhanced surface area. Finally, the developed electrode was applied to determine Pb 2+ and Cd 2+ in water samples, indicating that this electrode was sensitive, reliable and effective for the simultaneous determination of Pb 2+ and Cd 2+

  3. A Thin Film Nanocomposite Membrane with MCM-41 Silica Nanoparticles for Brackish Water Purification

    Directory of Open Access Journals (Sweden)

    Mohammed Kadhom

    2016-12-01

    Full Text Available Thin film nanocomposite (TFN membranes containing MCM-41 silica nanoparticles (NPs were synthesized by the interfacial polymerization (IP process. An m-phenylenediamine (MPD aqueous solution and an organic phase with trimesoyl chloride (TMC dissolved in isooctane were used in the IP reaction, occurring on a nanoporous polysulfone (PSU support layer. Isooctane was introduced as the organic solvent for TMC in this work due to its intermediate boiling point. MCM-41 silica NPs were loaded in MPD and TMC solutions in separate experiments, in a concentration range from 0 to 0.04 wt %, and the membrane performance was assessed and compared based on salt rejection and water flux. The prepared membranes were characterized via scanning electron microscopy (SEM, transmission electron microscopy (TEM, contact angle measurement, and attenuated total reflection Fourier transform infrared (ATR FT-IR analysis. The results show that adding MCM-41 silica NPs into an MPD solution yields slightly improved and more stable results than adding them to a TMC solution. With 0.02% MCM-41 silica NPs in the MPD solution, the water flux was increased from 44.0 to 64.1 L/m2·h, while the rejection virtually remained the same at 95% (2000 ppm NaCl saline solution, 25 °C, 2068 kPa (300 psi.

  4. A Thin Film Nanocomposite Membrane with MCM-41 Silica Nanoparticles for Brackish Water Purification.

    Science.gov (United States)

    Kadhom, Mohammed; Yin, Jun; Deng, Baolin

    2016-12-06

    Thin film nanocomposite (TFN) membranes containing MCM-41 silica nanoparticles (NPs) were synthesized by the interfacial polymerization (IP) process. An m -phenylenediamine (MPD) aqueous solution and an organic phase with trimesoyl chloride (TMC) dissolved in isooctane were used in the IP reaction, occurring on a nanoporous polysulfone (PSU) support layer. Isooctane was introduced as the organic solvent for TMC in this work due to its intermediate boiling point. MCM-41 silica NPs were loaded in MPD and TMC solutions in separate experiments, in a concentration range from 0 to 0.04 wt %, and the membrane performance was assessed and compared based on salt rejection and water flux. The prepared membranes were characterized via scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurement, and attenuated total reflection Fourier transform infrared (ATR FT-IR) analysis. The results show that adding MCM-41 silica NPs into an MPD solution yields slightly improved and more stable results than adding them to a TMC solution. With 0.02% MCM-41 silica NPs in the MPD solution, the water flux was increased from 44.0 to 64.1 L/m²·h, while the rejection virtually remained the same at 95% (2000 ppm NaCl saline solution, 25 °C, 2068 kPa (300 psi)).

  5. Development of pore interconnectivity/morphology in porous silica films investigated by cyclic voltammetry and slow positron annihilation spectroscopy

    International Nuclear Information System (INIS)

    Tang, Xiuqin; Xiong, Bangyun; Li, Qichao; Mao, Wenfeng; Xiao, Wei; Fang, Pengfei; He, Chunqing

    2015-01-01

    Highlights: •Porous silica films were studied by cyclic voltammetry and positron annihilation. •Highly interconnected pores were formed in the film fabricated with more CTAB. •Aligned nanochannels were observed in the porous flim prepared with 25 wt.% CTAB. •I − and Ps diffusion in the films was governed by pore interconnectivity/morphology. •Cyclic voltammetry is feasible to explore pore interconnectivity/morphology. -- Abstract: Cyclic voltammetry and positronium (Ps) 3γ-annihilation spectroscopy were applied to investigate pore interconnectivity/morphology of porous silica films fabricated with various loading of cetyltrimethyl ammonium bromide (CTAB). With increasing the ratio of CTAB up to 15 wt.%, the total charge Q, resulted from I − diffusion across the silica films, increased remarkably, indicative of formation of highly interconnected pores in the films prepared with more porogen. However, it decreased dramatically with further loading CTAB of 25 wt.%. Interestingly, 3γ-annihilation fraction I 3γ due to a triplet-state Ps (ortho-positronium, o-Ps) emission from the silica films showed a similar behavior as a function of CTAB loading. The abnormal decrement in Q and I 3γ in the film fabricated with 25 wt.% CTAB was well explained by formation of long nanochannels aligning parallel to the film surface. The results indicated that the total charge Q and Ps 3γ-annihilation fraction were closely associated with I − and Ps diffusion governed by the pore interconnectivity/morphology of the silica films, which made cyclic voltammetry possible to be a feasible tool to characterize pore interconnectivity/morphology of porous thin films

  6. Steady state and time resolved fluorescence studies of azadioxatriangulenium (ADOTA) fluorophore in silica and PVA thin films

    DEFF Research Database (Denmark)

    Chib, Rahul; Raut, Sangram; Shah, Sunil

    2015-01-01

    A cationic azadioxatriangulenium dye was entrapped in silica thin films obtained by the sol-gel process and in poly (vinyl) alcohol (PVA) thin films. Azadioxatriangulenium is a red emitting fluorophore with a long fluorescence lifetime of ∼20 ns. The fluorescent properties of azadioxatriangulenium...

  7. Synthesis and electrical characterization of low-temperature thermal-cured epoxy resin/functionalized silica hybrid-thin films for application as gate dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Na, Moonkyong, E-mail: nmk@keri.re.kr [HVDC Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); System on Chip Chemical Process Research Center, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784 (Korea, Republic of); Kang, Young Taec [Creative and Fundamental Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); Department of Polymer Science and Engineering, Pusan National University, Busan, 609-735 (Korea, Republic of); Kim, Sang Cheol [HVDC Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); Kim, Eun Dong [Creative and Fundamental Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of)

    2013-07-31

    Thermal-cured hybrid materials were synthesized from homogenous hybrid sols of epoxy resins and organoalkoxysilane-functionalized silica. The chemical structures of raw materials and obtained hybrid materials were characterized using Fourier transform infrared spectroscopy. The thermal resistance of the hybrids was enhanced by hybridization. The interaction between epoxy matrix and the silica particles, which caused hydrogen bonding and van der Waals force was strengthened by organoalkoxysilane. The degradation temperature of the hybrids was improved by approximately 30 °C over that of the parent epoxy material. The hybrid materials were formed into uniformly coated thin films of about 50 nm-thick using a spin coater. An optimum mixing ratio was used to form smooth-surfaced hybrid films. The electrical property of the hybrid film was characterized, and the leakage current was found to be well below 10{sup −6} A cm{sup −2}. - Highlights: • Preparation of thermal-curable hybrid materials using epoxy resin and silica. • The thermal stability was enhanced through hybridization. • The insulation property of hybrid film was investigated as gate dielectrics.

  8. Effects of annealing time on the structure, morphology, and stress of gold–chromium bilayer film

    International Nuclear Information System (INIS)

    Zhang Hong; Wang Hu; Huang Hao-Peng; Jin Yun-Xia; Kong Fang-Yu; Cui Yun

    2016-01-01

    In this work, a 200-nm-thick gold film with a 10-nm-thick chromium layer used as an adhesive layer is fabricated on fused silica by the electron beam evaporation method. The effects of annealing time at 300 °C on the structure, morphology and stress of the film are studied. We find that chromium could diffuse to the surface of the film by formatting a solid solution with gold during annealing. Meanwhile, chromium is oxidized on the surface and diffused downward along the grain grooves in the gold film. The various operant mechanisms that change the residual stresses of gold films for different annealing times are discussed. (paper)

  9. Optical and electrical properties of boron doped diamond thin conductive films deposited on fused silica glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ficek, M.; Sobaszek, M.; Gnyba, M. [Department of Metrology and Optoelectronics, Gdansk University of Technology, 11/12G. Narutowicza St., 80-233 Gdansk (Poland); Ryl, J. [Department of Electrochemistry, Corrosion and Material Engineering, Gdansk University of Technology, 11/12 Narutowicza St., 80-233 Gdansk (Poland); Gołuński, Ł. [Department of Metrology and Optoelectronics, Gdansk University of Technology, 11/12G. Narutowicza St., 80-233 Gdansk (Poland); Smietana, M.; Jasiński, J. [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, 75 Koszykowa St., 00-662 Warsaw (Poland); Caban, P. [Institute of Electronic Materials Technology, 133 Wolczynska St., 01-919 Warsaw (Poland); Bogdanowicz, R., E-mail: rbogdan@eti.pg.gda.pl [Department of Metrology and Optoelectronics, Gdansk University of Technology, 11/12G. Narutowicza St., 80-233 Gdansk (Poland); Materials and Process Simulation Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2016-11-30

    Highlights: • Growth of 60% of transmittance diamond films with resistivity as low as 48 Ω cm. • Two step seeding process of fused silica: plasma hydrogenation and wet seeding. • Nanodiamond seeding density of 2 × 10{sup 10} cm{sup −2} at fused silica substrates. • High refractive index (2.4 @550 nm) was achieved for BDD films deposited at 500 °C. - Abstract: This paper presents boron-doped diamond (BDD) film as a conductive coating for optical and electronic purposes. Seeding and growth processes of thin diamond films on fused silica have been investigated. Growth processes of thin diamond films on fused silica were investigated at various boron doping level and methane admixture. Two step pre-treatment procedure of fused silica substrate was applied to achieve high seeding density. First, the substrates undergo the hydrogen plasma treatment then spin-coating seeding using a dispersion consisting of detonation nanodiamond in dimethyl sulfoxide with polyvinyl alcohol was applied. Such an approach results in seeding density of 2 × 10{sup 10} cm{sup −2}. The scanning electron microscopy images showed homogenous, continuous and polycrystalline surface morphology with minimal grain size of 200 nm for highly boron doped films. The sp{sup 3}/sp{sup 2} ratio was calculated using Raman spectra deconvolution method. A high refractive index (range of 2.0–2.4 @550 nm) was achieved for BDD films deposited at 500 °C. The values of extinction coefficient were below 0.1 at λ = 550 nm, indicating low absorption of the film. The fabricated BDD thin films displayed resistivity below 48 Ohm cm and transmittance over 60% in the visible wavelength range.

  10. Preparation of silane-functionalized silica films via two-step dip coating sol–gel and evaluation of their superhydrophobic properties

    International Nuclear Information System (INIS)

    Ramezani, Maedeh; Vaezi, Mohammad Reza; Kazemzadeh, Asghar

    2014-01-01

    Highlights: • Superhydrophobic silica film was prepared by sol–gel process. • The surfaces exhibited superhydrophobicity with water contact angle greater than 150°. • AFM images showed the roughness increases with increasing the percentage of silylation agent. • Before and after modification, the particle size of silica was lower than 50 nm. - Graphical abstract: Schematic illustration of the surface modification of the silica nanoparticle by iso-OTMS on the glass substrate. - Abstract: In this paper, we study the two-step dip coating via a sol–gel process to prepare superhydrophobic silica films on the glass substrate. The water repellency of the silica films was controlled by surface silylation method using isooctyltrimethoxysilane (iso-OTMS) as a surface modifying agent. Silica alcosol was synthesized by keeping the molar ratio of ethyltriethoxysilane (ETES) precursor, ethanol (EtOH) solvent, water (H 2 O) was kept constant at 1:36:6.6 respectively, with 6 M NH 4 OH throughout the experiment and the percentages of hydrophobic agent in hexane bath was varied from 0 to 15 vol.%. The static water contact angle values of the silica films increased from 108° to 160° with an increase in the vol.% of iso-OTMS. At 15 vol%. of iso-OTMS, the silica film shows static water contact angle as high as 160°. The superhydrophobic silica films are thermally stable up to 440 °C and above this temperature, the silica films lose superhydrophobicity. By controlling the primer particle size of SiO 2 about 26 nm, leading to decrease the final size of silica nanoparticles after modification of nanoparticles by isooctyltrimethoxysilane about 42 nm. The films are transparent and have uniform size on the surface. The silica films have been characterized by atomic force microscopy (AFM), fourier transform infrared spectroscopy (FT-IR), transparency, contact angle measurement (CA), Zeta-potential, Thermal stability by TG–DTA analysis

  11. Solution-processable precursor route for fabricating ultrathin silica film for high performance and low voltage organic transistors

    Institute of Scientific and Technical Information of China (English)

    Shujing Guo; Liqiang Li; Zhongwu Wang; Zeyang Xu; Shuguang Wang; Kunjie Wu; Shufeng Chen; Zongbo Zhang; Caihong Xu; Wenfeng Qiu

    2017-01-01

    Silica is one of the most commonly used materials for dielectric layer in organic thin-film transistors due to its excellent stability,excellent electrical properties,mature preparation process,and good compatibility with organic semiconductors.However,most of conventional preparation methods for silica film are generally performed at high temperature and/or high vacuum.In this paper,we introduce a simple solution spin-coating method to fabricate silica thin film from precursor route,which possesses a low leakage current,high capacitance,and low surface roughness.The silica thin film can be produced in the condition of low temperature and atmospheric environment.To meet various demands,the thickness of film can be adjusted by means of preparation conditions such as the speed of spin-coating and the concentration of solution.The p-type and n-type organic field effect transistors fabricated by using this film as gate electrodes exhibit excellent electrical performance including low voltage and high performance.This method shows great potential for industrialization owing to its characteristic of low consumption and energy saving,time-saving and easy to operate.

  12. Luminescent hybrid films obtained by covalent grafting of terbium complex to silica network

    International Nuclear Information System (INIS)

    Liu Fengyi; Fu Lianshe; Wang Jun; Liu Ze; Li Huanrong; Zhang Hongjie

    2002-01-01

    Luminescent hybrid thin films consisting of terbium complex covalently bonded to a silica-based network have been obtained in situ via a sol-gel approach. A new monomer, N-(4-benzoic acid-yl), N'-(propyltriethoxysilyl)urea (PABI), has been synthesized by grafting isocyanatopropyltriethoxysilane (ICPTES) to p-aminobenzoic acid and characterized by 1 H NMR, IR and MS. The monomer acts as a ligand for Tb 3+ ion and as a sol-gel precursor. Band emission from Tb 3+ ion due to an efficient ligand-to-metal energy transfer was observed by UV excitation. The decay curves of Tb 3+ in the hybrid films were measured. The energy difference between the triplet state energy of PABI and the 5 D 4 level of Tb 3+ ion falls in the exciting range to sensitize Tb 3+ ion fluorescence

  13. Stability of erbium and silver implanted in silica-titania sol-gel films

    International Nuclear Information System (INIS)

    Ramos, A.R.; Marques, C.; Alves, E.; Marques, A.C.; Almeida, R.M.

    2005-01-01

    We implanted silica-titania sol-gel films with 3 x 10 15 at./cm 2 , 180 keV Er + and 6 x 10 16 at./cm 2 , 140 keV Ag + ions. The energies were chosen so that the profiles of Ag and Er overlap. RBS and ERDA were used to study the behaviour of Ag, Er and H during the heat treatments used to density the films. Implantation causes H depletion at the film surface and an increase in H concentration just beneath the implanted Ag and Er profiles. The total H content decreases by 27% to 75% during implantation. During annealing the H content decreases, with an almost complete H loss after annealing for 35 min at 800 deg. C. The Ag profile remains stable up to 600 deg. C. Above 700 deg. C Ag becomes increasingly mobile. Annealing at 800 deg. C for 35 min results in a nearly constant Ag distribution in the film. The Er profile remains unchanged with heat treatment up to the maximum temperature used (800 deg. C)

  14. Polymer-Silica nanoparticles composite films as protective coatings for stone-based monuments

    Energy Technology Data Exchange (ETDEWEB)

    Manoudis, P [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki (Greece); Papadopoulou, S [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki (Greece); Karapanagiotis, I [' Ormylia' Art Diagnosis Centre, Ormylia, Chalkidiki, 63071 (Greece); Tsakalof, A [Medical Department, University of Thessaly, Larissa, 41222 (Greece); Zuburtikudis, I [Department of Industrial Design Engineering, TEI of Western Macedonia, Kozani, 50100 (Greece); Panayiotou, C [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki (Greece)

    2007-04-15

    The decrease of surface energy of mineral substrates similar to those used in many stone monuments of cultural heritage by the application of protective polymer coatings along with the simultaneous increase of their surface roughness can increase their ability to repel water substantially. In this work, the effect of artificially induced roughness on the water repellency of mineral substrates coated with protective polymer films was investigated. Natural marble samples or home made calcium carbonate blocks were tried as the mineral substrates. The roughness increase was achieved by mineral chemical etching or by creation of nanoscale binary composition film on the substrate surface. PMMA and PFPE were the polymers used, while different-sized silica nanoparticles were employed for the production of the nanocomposite films. Examination of the coated and uncoated surfaces with profilometry and AFM and measurements of water contact angles reveal a pronounced effect of the surface roughness on water repellency. Especially in the case of nanocomposite coatings, the surfaces become super-hydrophobic. This result indicates that the nanoscale binary composition film scheme, which is characterized by its simplicity and low cost, is a suitable candidate for the water protection of stone-based monuments on large scale.

  15. Polymer-Silica nanoparticles composite films as protective coatings for stone-based monuments

    International Nuclear Information System (INIS)

    Manoudis, P; Papadopoulou, S; Karapanagiotis, I; Tsakalof, A; Zuburtikudis, I; Panayiotou, C

    2007-01-01

    The decrease of surface energy of mineral substrates similar to those used in many stone monuments of cultural heritage by the application of protective polymer coatings along with the simultaneous increase of their surface roughness can increase their ability to repel water substantially. In this work, the effect of artificially induced roughness on the water repellency of mineral substrates coated with protective polymer films was investigated. Natural marble samples or home made calcium carbonate blocks were tried as the mineral substrates. The roughness increase was achieved by mineral chemical etching or by creation of nanoscale binary composition film on the substrate surface. PMMA and PFPE were the polymers used, while different-sized silica nanoparticles were employed for the production of the nanocomposite films. Examination of the coated and uncoated surfaces with profilometry and AFM and measurements of water contact angles reveal a pronounced effect of the surface roughness on water repellency. Especially in the case of nanocomposite coatings, the surfaces become super-hydrophobic. This result indicates that the nanoscale binary composition film scheme, which is characterized by its simplicity and low cost, is a suitable candidate for the water protection of stone-based monuments on large scale

  16. Structural effect of monomer type on properties of copolyimides and copolyimide-silica hybrid materials

    Directory of Open Access Journals (Sweden)

    Kizilkaya Canan

    2015-01-01

    Full Text Available In this work, the effect of two different diamine monomers, containing phosphine oxide, on thermal, mechanical and morphological properties of copolyimides and their hybrid materials was investigated. Gas separation properties of the synthesized copolyimides were also analysed. Two different diamine monomers with phosphine oxide were bis(3-aminophenyl phenylphosphine oxide (BAPPO and bis(3-aminophenoxy-4-phenyl phenylphosphine oxide (m-BAPPO. In the synthesis of copolyimides 3,3’-diamino-diphenyl sulfone (DDS was also used as the diamine, as well as 2,2’-bis(3,4-dicarboxyphenylhexafluoropropane dianhydride (6FDA. Copolyimide films were prepared by thermal imidization. Hybrid materials containing 5 % SiO2 were synthesised further by sol-gel technique. The Fourier-transform infrared spectroscopy (FTIR, Nuclear magnetic resonance spectroscopy (NMR confirmed the expected structure. Dynamic mechanical analysis (DMA demonstrated that m-BAPPO based copolyimides had lower glass transition temperatures (Tg than BAPPO based copolyimides. m-BAPPO containing copolyimide without silica shifted the thermal decomposition temperature to a higher value. The moduli and strength values of BAPPO diamine containing copolyimide and its hybrid were higher than those of m-BAPPO containing materials. The contact angle measurements showed the hydrophobicity. Scanning electron microscope (SEM analysis exhibited the silica particles dispersion in the copolyimides. These copolyimides may be used in the coating industry. The CO2 permeability and the permselectivity were the highest among the other values in this study, when m-BAPPO containing copolyimide in the absence of silica was used. The gas permeabilities obtained from this work were in this decreasing order: PCO2 > PO2 > PN2.

  17. Mesoporous Structure Control of Silica in Room-Temperature Synthesis under Basic Conditions

    Directory of Open Access Journals (Sweden)

    Jeong Wook Seo

    2015-01-01

    Full Text Available Various types of mesoporous silica, such as continuous cubic-phase MCM-48, hexagonal-phase MCM-41, and layer-phase spherical silica particles, have been synthesized at room temperature using cetyltrimethylammonium bromide as a surfactant, ethanol as a cosurfactant, tetraethyl orthosilicate as a silica precursor, and ammonia as a condensation agent. Special care must be taken both in the filtering of the resultant solid products and in the drying process. In the drying process, further condensation of the silica after filtering was induced. As the surfactant and cosurfactant concentrations in the reaction mixture increased and the NH3 concentration decreased, under given conditions, continuous cubic MCM-48 and layered silica became the dominant phases. A cooperative synthesis mechanism, in which both the surfactant and silica were involved in the formation of mesoporous structures, provided a good explanation of the experimental results.

  18. In situ crystallization of b-oriented MFI films on plane and curved substrates coated with a mesoporous silica layer

    KAUST Repository

    Deng, Zhiyong

    2013-05-01

    A simple and reproducible method is presented for preparing b-oriented MFI films on plane (disc) and curved (hollow fiber) supports by in situ hydrothermal synthesis. A mesoporous silica (sub-)layer was pre-coated on the supports by dip coating followed by a rapid thermal calcination step (973 K during 1 min) to reduce the number of grain boundaries while keeping the hydrophilic behavior of silica. The role of the silica sub-layer is not only to smoothen the substrate surface, but also to provide a silica source to promote the nucleation and growth of zeolite crystals via a heterogeneous nucleation mechanism (zeolitization), and adsorb zeolite moieties generated in the synthesis solution via a homogeneous nucleation mechanism. A monolayer of b-oriented MFI crystals was obtained on both supports after 3 h synthesis time with a moderate degree of twinning on the surface. © 2013 Elsevier Ltd.

  19. Structural modification of silica glass by laser scanning

    International Nuclear Information System (INIS)

    Zhao Jian; Sullivan, James; Zayac, John; Bennett, Ted D.

    2004-01-01

    The thermophysical nature of rapid CO 2 laser heating of silica glass is explored using a numerical simulation that considers the structural state of the glass, as characterized by the fictive temperature. The fictive temperature reflects the thermodynamic temperature at which the glass structure would be in equilibrium. To demonstrate that the thermophysical model can accurately predict the structural change in the glass, the fictive temperature is measured experimentally utilizing the fact that the fictive temperature change corresponds to a change of glass properties that can be revealed through wet chemical etching. The relationship between the etch rate and the fictive temperature is determined by preparing and etching samples of known fictive temperature. Wet chemical etching is used to measure the fictive temperature over the entire laser affected zone and the results are found to compare favorably with the results of the thermophysical model. The model and experimental measurements demonstrate that rapid laser processing results in an increased fictive temperature near the surface of the glass. The fictive temperature increase is about 1000 K and is uniform to within 5% over the laser affected zone. Near the boundary of this zone, the fictive temperature transitions abruptly to the value of the surrounding untreated glass

  20. Structural evolution of silica sols modified with formamide

    Directory of Open Access Journals (Sweden)

    Lenza R.F.S.

    2001-01-01

    Full Text Available In this work we investigated the influence of formamide on the acid-catalyzed sol-gel process by Fourier transform infrared spectroscopy (FTIR. Three silica sols were studied: Sol catalyzed with nitric acid without formamide, sol catalyzed with nitric acid containing formamide and sol catalyzed with a mixture of nitric acid and hydrofluoric acid and modified with formamide. Following the time evolution of both the Si-(OH stretching vibration at around 950 cm-1 and the Si-O-(Si vibration between 1040 cm-1 and 1200 cm-1 we were able to describe the structural evolution of each sol. The curve of evolution of Si-(OH stretching vibration corresponding to sol A has a simple asymptotic evolution. In the case of formamide containing sol, we observed a two-step structural evolution indicating that for the system containing formamide the polymerization goes through a temporary stabilization of oligomers, which can explain the non-variation of the Si-O(H bond wavenumber for a certain time. Gelation times were of several days for gels without formamide and few hours for gels containing additive. The presence of additive resulted in a highly interconnected gel.

  1. Growth of ordered silver nanoparticles in silica film mesostructured with a triblock copolymer PEO-PPO-PEO

    International Nuclear Information System (INIS)

    Bois, L.; Chassagneux, F.; Parola, S.; Bessueille, F.; Battie, Y.; Destouches, N.; Boukenter, A.; Moncoffre, N.; Toulhoat, N.

    2009-01-01

    Elaboration of mesostructured silica films with a triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide, (PEO-PPO-PEO) and controlled growth of silver nanoparticles in the mesostructure are described. The films are characterized using UV-visible optical absorption spectroscopy, TEM, AFM, SEM, X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Organized arrays of spherical silver nanoparticles with diameter between 5 and 8 nm have been obtained by NaBH 4 reduction. The size and the repartition of silver nanoparticles are controlled by the film mesostructure. The localization of silver nanoparticles exclusively in the upper-side part of the silica-block copolymer film is evidenced by RBS experiment. On the other hand, by using a thermal method, 40 nm long silver sticks can be obtained, by diffusion and coalescence of spherical particles in the silica-block copolymer layer. In this case, migration of silver particles toward the glass substrate-film interface is shown by the RBS experiment. - Graphical abstract: Growth of silver nanoparticles in a mesostructured block copolymer F127-silica film is performed either by a chemical route involving NaBH 4 reduction or by a thermal method. An array of spherical silver nanoparticles with 10 nm diameter on the upper-side of the mesostructured film or silver sticks long of 40 nm with a preferential orientation are obtained according to the method used. a: TEM image of the Fag5SiNB sample illustrating the silver nanoparticles array obtained by the chemical process; b: HR-TEM image of the Fag20Sid2 sample illustrating the silver nanosticks obtained by the thermal process.

  2. Preparation of novel film-forming armoured latexes using silica nanoparticles as a pickering emulsion stabiliser.

    Science.gov (United States)

    Shiraz, Hana; Peake, Simon J; Davey, Tim; Cameron, Neil R; Tabor, Rico F

    2018-05-15

    Film-forming polymer latex particles of diameter acrylate (BA) as co-monomers, potassium persulphate (KPS) as an initiator and a commercially available colloidal nano-silica (Ludox®-TM40). It was found that pH control before polymerisation using methacrylic acid (MAA) facilitated the formation of armoured latexes, and mechanistic features of this process are discussed. An alternative, more robust protocol was developed whereby addition of vinyltriethoxysilane (VTES) to control wettability resulted in latexes completely armoured in colloidal nano-silica. The latexes were characterised using SEM, cryo-TEM and AFM imaging techniques. The mechanism behind the adsorption was investigated through surface pressure and contact angle measurements to understand the factors that influence this irreversible adsorption. Results indicate that nanoparticle attachment (but intriguingly not latex size) is dependent on particle wettability, providing new insight into the formation of nanoparticle-armoured latexes, along with opportunities for further development of diversely functionalized inorganic/organic polymer composite particles. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Fabrication of semi-transparent super-hydrophobic surface based on silica hierarchical structures

    KAUST Repository

    Chen, Ping-Hei; Hsu, Chin-Chi; Lee, Pei-Shan; Lin, Chao-Sung

    2011-01-01

    -coating silica particles suspended in a precursor solution of silane, ethanol, and H2O with molar ratio of 1:4:4. The resulting super hydrophobic films were characterized by scanning electron microscopy (SEM), optical transmission, and contact angle measurements

  4. Large third-order optical nonlinearity in vertically oriented mesoporous silica thin films embedded with Ag nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Min; Liu, Qiming, E-mail: qmliu@whu.edu.cn [Wuhan University, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology (China)

    2016-12-15

    Taking advantage of the channel confinement of mesoporous films to prevent the agglomeration of Ag nanoparticles to achieve large third-order optical nonlinearity in amorphous materials, Ag-loaded composite mesoporous silica film was prepared by the electrochemical deposition method on ITO substrate. Ag ions were firstly transported into the channels of mesoporous film by the diffusion and binding force of channels, which were reduced to nanoparticles by applying suitable voltage. The existence and uniform distribution of Ag nanoparticles ranging in 1–10 nm in the mesoporous silica thin films were exhibited by UV spectrophotometer, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) measurements. The third-order optical nonlinearity induced by Ag nanoparticles was studied by the Z-scan technique. Due to the local field surface plasmon resonance, the maximum third-order nonlinear optical susceptibility of Ag-loaded composite mesoporous silica film is 1.53×10{sup −10} esu, which is 1000 times larger than that of the Ag-contained chalcogenide glasses which showed large nonlinearity in amorphous materials.

  5. Unraveling the atomic structure of biogenic silica: evidence of the structural association of Al and Si in diatom frustules

    Science.gov (United States)

    Gehlen, M.; Beck, L.; Calas, G.; Flank, A.-M.; Van Bennekom, A. J.; Van Beusekom, J. E. E.

    2002-05-01

    We used X-ray absorption spectroscopy at the Al K-edge to investigate the atomic structure of biogenic silica and to assess the effect of Al on its crystal chemistry. Our study provides the first direct evidence for a structural association of Al and Si in biogenic silica. In samples of cultured diatoms, Al is present exclusively in fourfold coordination. The location and relative intensity of X-ray absorption near-edge structure (XANES) features suggests the structural insertion of tetrahedral Al inside the silica framework synthesized by the organism. In diatom samples collected in the marine environment, Al is present in mixed six- and fourfold coordination. The relative intensity of XANES structures indicates the coexistence of structural Al with a clay component, which most likely reflects sample contamination by adhering mineral particles. Extended X-ray absorption fine structure spectroscopy has been used to get Al-O distances in biogenic silica of cultured diatoms, confirming a tetrahedral coordination. Because of its effect on solubility and reaction kinetics of biogenic silica, the structural association between Al and biogenic silica at the stage of biosynthesis has consequences for the use of sedimentary biogenic silica as an indicator of past environmental conditions.

  6. Photocrosslinked nanocomposite hydrogels from PEG and silica nanospheres: Structural, mechanical and cell adhesion characteristics

    International Nuclear Information System (INIS)

    Gaharwar, Akhilesh K.; Rivera, Christian; Wu, Chia-Jung; Chan, Burke K.; Schmidt, Gudrun

    2013-01-01

    Photopolymerized hydrogels are extensively investigated for various tissue engineering applications, primarily due to their ability to form hydrogels in a minimally invasive manner. Although photocrosslinkable hydrogels provide necessary biological and chemical characteristics to mimic cellular microenvironments, they often lack sufficient mechanical properties. Recently, nanocomposite approaches have demonstrated potential to overcome these deficits by reinforcing the hydrogel network with. In this study, we investigate some physical, chemical, and biological properties of photocrosslinked poly(ethylene glycol) (PEG)-silica hydrogels. The addition of silica nanospheres significantly suppresses the hydration degree of the PEG hydrogels, indicating surface interactions between the silica nanospheres and the polymer chains. No significant change in hydrogel microstructure or average pore size due to the addition of silica nanospheres was observed. However, addition of silica nanospheres significantly increases both the mechanical strength and the toughness of the hydrogel networks. The biological properties of these nanocomposite hydrogels were evaluated by seeding fibroblast cells on the hydrogel surface. While the PEG hydrogels showed minimum cell adhesion, spreading and proliferation, the addition of silica nanospheres enhanced initial cell adhesion, promoted cell spreading and increased the metabolic activity of the cells. Overall, results indicate that the addition of silica nanospheres improves the mechanical stiffness and cell adhesion properties of PEG hydrogels and can be used for biomedical applications that required controlled cell adhesion. - Graphical abstract: Structural, mechanical and biological properties of photocrosslinked nanocomposite hydrogels from silica and poly(ethylene oxide) are investigated. Silica reinforce the hydrogel network and improved mechanical strength. Addition of induces cell adhesion characteristic properties for various

  7. Investigation of durability of silica fume concretes in coastal structures within tidal zone

    International Nuclear Information System (INIS)

    Ganjian, E.; Sadeghi Pouya, H.

    2003-01-01

    In recent decade use of silica fume has been become greater in coastal concrete structures in the persona gulf, to increase durability of those establishments. In this research the durability of cement passers and concrete cubes with use of 7 and 10 percent of silica fume as a cement replacement have been investigated in three curing conditions (fresh water, coast of sea and simulation bonds) by measuring compressive strengths and capillary absorption. Silica fume specimens under wetting and drying condition showed more strength loss after 180 days compare to samples without silica fume or cured in the fresh water. In addition the greater silica fume amount in specimens cured within tidal zone and under wetting and drying simulation, the more water absorption by capillary. According to the results, good correspondence between simulated condition and real site exposure was obtained

  8. Facile synthesis of mesoporous silica sublayer with hierarchical pore structure on ceramic membrane using anionic polyelectrolyte.

    Science.gov (United States)

    Kang, Taewook; Oh, Seogil; Kim, Honggon; Yi, Jongheop

    2005-06-21

    A facile method for introducing mesoporous silica sublayer onto the surface of a ceramic membrane for use in liquid-phase separation is described. To reduce the electrostatic repulsion between the mesoporous silica sol and the ceramic membrane in highly acidic conditions (pH ceramic membrane, as confirmed by experimental titration data. Consistent with the titration results, the amount of mesoporous silica particles on the surface of the ceramic membrane was low, in the absence of PSS- treatment, whereas mesoporous silica sublayer with hierarchical pore structure was produced, when 1 wt % PSS- was used. The results show that mesoporous silica grows in the confined surface, eventually forming a multistacked surface architecture. The mesoporous silica sublayer contained uniform, ordered (P6 mm) mesopores of ca. 7.5 nm from mesoporous silica as well as macropores ( approximately mum) from interparticle voids, as evidenced by transmission electron microscopy and scanning electron microscopy analyses. The morphologies of the supported mesoporous silica could be manipulated, thus permitting the generation of uniform needlelike forms or uniform spheroid particles by varying the concentration of PSS-.

  9. Investigation of structural properties associated with alkali-silica reaction by means of macro- and micro-structural analysis

    International Nuclear Information System (INIS)

    Mo Xiangyin; Fournier, Benoit

    2007-01-01

    Structural properties associated with alkali-silica reaction were systematically investigated by means of macro-structural accelerated mortar prism expansion levels testing, combined with micro-structural analysis. One part of this study is to determine the reactivity of the aggregate by means of accelerated mortar bar tests, and also to evaluate perlite aggregate constituents, especially the presence of deleterious components and find main causes of the alkali-silica reaction, which was based on the petrographic studies by optical microscope and the implication of X-ray diffraction on the aggregate. Results implied that the aggregate was highly alkali-silica reactive and the main micro-crystalline quartz-intermediate character and matrix that is mainly composed of chalcedony are potentially suitable for alkali-silica reaction. The other part is to study the long-term effect of lithium salts against alkali-silica reaction by testing accelerated mortar prism expansion levels. The macro-structural results were also consistent with the micro-structural mechanisms of alkali-silica reaction of mortar prisms containing this aggregate and the effect of chemical admixtures by means of the methods of scanning electron microscope-X-ray energy-dispersive spectroscopy and X-ray diffraction. It was indicated by these techniques that lithium salts, which were introduced into concrete containing reactive aggregate at the mixing stage, suppressed the alkali-silica reaction by producing non-expansive crystalline materials

  10. Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials.

    Science.gov (United States)

    Hesemann, Peter; Nguyen, Thy Phung; Hankari, Samir El

    2014-04-11

    The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS) recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA), mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the "anionic templating" strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches.

  11. Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials

    Directory of Open Access Journals (Sweden)

    Peter Hesemann

    2014-04-01

    Full Text Available The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA, mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the “anionic templating” strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches.

  12. Two-dimensional silica: Structural, mechanical properties, and strain-induced band gap tuning

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Enlai; Xie, Bo [Applied Mechanics Laboratory, Department of Engineering Mechanics, and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China); Xu, Zhiping, E-mail: xuzp@tsinghua.edu.cn [Applied Mechanics Laboratory, Department of Engineering Mechanics, and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

    2016-01-07

    Two-dimensional silica is of rising interests not only for its practical applications as insulating layers in nanoelectronics, but also as a model material to understand crystals and glasses. In this study, we examine structural and electronic properties of hexagonal and haeckelite phases of silica bilayers by performing first-principles calculations. We find that the corner-sharing SiO{sub 4} tetrahedrons in these two phases are locally similar. The robustness and resilience of these tetrahedrons under mechanical perturbation allow effective strain engineering of the electronic structures with band gaps covering a very wide range, from of that for insulators, to wide-, and even narrow-gap semiconductors. These findings suggest that the flexible 2D silica holds great promises in developing nanoelectronic devices with strain-tunable performance, and lay the ground for the understanding of crystalline and vitreous phases in 2D, where bilayer silica provides an ideal test-bed.

  13. Structure and Properties of Silica Glass Densified in Cold Compression and Hot Compression

    Science.gov (United States)

    Guerette, Michael; Ackerson, Michael R.; Thomas, Jay; Yuan, Fenglin; Bruce Watson, E.; Walker, David; Huang, Liping

    2015-10-01

    Silica glass has been shown in numerous studies to possess significant capacity for permanent densification under pressure at different temperatures to form high density amorphous (HDA) silica. However, it is unknown to what extent the processes leading to irreversible densification of silica glass in cold-compression at room temperature and in hot-compression (e.g., near glass transition temperature) are common in nature. In this work, a hot-compression technique was used to quench silica glass from high temperature (1100 °C) and high pressure (up to 8 GPa) conditions, which leads to density increase of ~25% and Young’s modulus increase of ~71% relative to that of pristine silica glass at ambient conditions. Our experiments and molecular dynamics (MD) simulations provide solid evidences that the intermediate-range order of the hot-compressed HDA silica is distinct from that of the counterpart cold-compressed at room temperature. This explains the much higher thermal and mechanical stability of the former than the latter upon heating and compression as revealed in our in-situ Brillouin light scattering (BLS) experiments. Our studies demonstrate the limitation of the resulting density as a structural indicator of polyamorphism, and point out the importance of temperature during compression in order to fundamentally understand HDA silica.

  14. Nanoscale assembly of lanthanum silica with dense and porous interfacial structures.

    Science.gov (United States)

    Ballinger, Benjamin; Motuzas, Julius; Miller, Christopher R; Smart, Simon; Diniz da Costa, João C

    2015-02-03

    This work reports on the nanoscale assembly of hybrid lanthanum oxide and silica structures, which form patterns of interfacial dense and porous networks. It was found that increasing the molar ratio of lanthanum nitrate to tetraethyl orthosilicate (TEOS) in an acid catalysed sol-gel process alters the expected microporous metal oxide silica structure to a predominantly mesoporous structure above a critical lanthanum concentration. This change manifests itself by the formation of a lanthanum silicate phase, which results from the reaction of lanthanum oxide nanoparticles with the silica matrix. This process converts the microporous silica into the denser silicate phase. Above a lanthanum to silica ratio of 0.15, the combination of growth and microporous silica consumption results in the formation of nanoscale hybrid lanthanum oxides, with the inter-nano-domain spacing forming mesoporous volume. As the size of these nano-domains increases with concentration, so does the mesoporous volume. The absence of lanthanum hydroxide (La(OH)3) suggests the formation of La2O3 surrounded by lanthanum silicate.

  15. Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

    Directory of Open Access Journals (Sweden)

    Soliman Abdalla

    2016-02-01

    Full Text Available Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of four highly pure amorphous polymer films: polymethyl methacrylate (PMMA, polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher breakdown performance is a character of polyimide (PI and PMMA. Also, our experimental data shows that adding colloidal silica to PMMA and PI leads to a net decrease in the dielectric properties compared to the pure polymer.

  16. Influences of surface charge, size, and concentration of colloidal nanoparticles on fabrication of self-organized porous silica in film and particle forms.

    Science.gov (United States)

    Nandiyanto, Asep Bayu Dani; Suhendi, Asep; Arutanti, Osi; Ogi, Takashi; Okuyama, Kikuo

    2013-05-28

    Studies on preparation of porous material have attracted tremendous attention because existence of pores can provide material with excellent performances. However, current preparation reports described successful production of porous material with only partial information on charges, interactions, sizes, and compositions of the template and host materials. In this report, influences of self-assembly parameters (i.e., surface charge, size, and concentration of colloidal nanoparticles) on self-organized porous material fabrication were investigated. Silica nanoparticles (as a host material) and polystyrene (PS) spheres (as a template) were combined to produce self-assembly porous materials in film and particle forms. The experimental results showed that the porous structure and pore size were controllable and strongly depended on the self-assembly parameters. Materials containing highly ordered pores were effectively created only when process parameters fall within appropriate conditions (i.e., PS surface charge ≤ -30 mV; silica-to-PS size ratio ≤0.078; and silica-to-PS mass ratio of about 0.50). The investigation of the self-assembly parameter landscape was also completed using geometric considerations. Because optimization of these parameters provides significant information in regard to practical uses, results of this report could be relevant to other functional properties.

  17. Basic evaluation of typical nanoporous silica nanoparticles in being drug carrier: Structure, wettability and hemolysis.

    Science.gov (United States)

    Li, Jing; Guo, Yingyu

    2017-04-01

    Herein, the present work devoted to study the basic capacity of nanoporous silica nanoparticles in being drug carrier that covered structure, wettability and hemolysis so as to provide crucial evaluation. Typical nanoporous silica nanoparticles that consist of nanoporous silica nanoparticles (NSN), amino modified nanoporous silica nanoparticles (amino-NSN), carboxyl modified nanoporous silica nanoparticles (carboxyl-NSN) and hierachical nanoporous silica nanoparticles (hierachical-NSN) were studied. The results showed that their wettability and hemolysis were closely related to structure and surface modification. Basically, wettability became stronger as the amount of OH on the surface of NSN was higher. Both large nanopores and surface modification can reduce the wettability of NSN. Furthermore, NSN series were safe to be used when they circulated into the blood in low concentration, while if high concentration can not be avoided during administration, high porosity or amino modification of NSN were safer to be considered. It is believed that the basic evaluation of NSN can make contribution in providing scientific instruction for designing drug loaded NSN systems. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Fabrication Flexible and Luminescent Nanofibrillated Cellulose Films with Modified SrAl2O4: Eu, Dy Phosphors via Nanoscale Silica and Aminosilane

    Directory of Open Access Journals (Sweden)

    Longfei Zhang

    2018-05-01

    Full Text Available Flexible 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO-oxidized nanofibrillated cellulose (ONFC films with long afterglow luminescence containing modified SrAl2O4: Eu2+, Dy3+ (SAOED phosphors were fabricated by a template method. Tetraethyl orthosilicate (TEOS and (3-aminopropyl trimethoxy-silane (APTMS were employed cooperatively to improve the water resistance and compatibility of the SAOED particles in the ONFC suspension. The structure and morphology after modification evidenced the formation of a superior SiO2 layer and coarse amino-compounds on the surface of the phosphors. Homogeneous dispersions containing ONFC and the modified phosphors were prepared and the interface of composite films containing the amino-modified particles showed a more closely packed structure and had less voids at the interface between the cellulose and luminescent particles than that of silica-modified phosphors. The emission spectra for luminescent films showed a slight blue shift (3.2 nm at around 512 nm. Such flexible films with good luminescence, thermal resistance, and mechanical properties can find applications in fields like luminous flexible equipment, night indication, and portable logo or labels.

  19. Patternable Poly(chloro-p-xylylene Film with Tunable Surface Wettability Prepared by Temperature and Humidity Treatment on a Polydimethylsiloxane/Silica Coating

    Directory of Open Access Journals (Sweden)

    Yonglian Yu

    2018-03-01

    Full Text Available Poly(chloro-p-xylylene (PPXC film has a water contact angle (WCA of only about 84°. It is necessary to improve its hydrophobicity to prevent liquid water droplets from corroding or electrically shorting metallic circuits of semiconductor devices, sensors, microelectronics, and so on. Herein, we reported a facile approach to improve its surface hydrophobicity by varying surface pattern structures under different temperature and relative humidity (RH conditions on a thermal curable polydimethylsiloxane (PDMS and hydrophobic silica (SiO2 nanoparticle coating. Three distinct large-scale surface patterns were obtained mainly depending on the contents of SiO2 nanoparticles. The regularity of patterns was mainly controlled by the temperature and RH conditions. By changing the pattern structures, the surface wettability of PPXC film could be improved and its WCA was increased from 84° to 168°, displaying a superhydrophobic state. Meanwhile, it could be observed that water droplets on PPXC film with superhydrophobicity were transited from a “Wenzel” state to a “Cassie” state. The PPXC film with different surface patterns of 200 μm × 200 μm and the improved surface hydrophobicity showed wide application potentials in self-cleaning, electronic engineering, micro-contact printing, cell biology, and tissue engineering.

  20. Preparation of thick silica coatings on carbon fibers with fine-structured silica nanotubes induced by a self-assembly process

    Directory of Open Access Journals (Sweden)

    Benjamin Baumgärtner

    2017-05-01

    Full Text Available A facile method to coat carbon fibers with a silica shell is presented in this work. By immobilizing linear polyamines on the carbon fiber surface, the high catalytic activity of polyamines in the sol–gel-processing of silica precursors is used to deposit a silica coating directly on the fiber’s surface. The surface localization of the catalyst is achieved either by attaching short-chain polyamines (e.g., tetraethylenepentamine via covalent bonds to the carbon fiber surface or by depositing long-chain polyamines (e.g., linear poly(ethylenimine on the carbon fiber by weak non-covalent bonding. The long-chain polyamine self-assembles onto the carbon fiber substrate in the form of nanoscopic crystallites, which serve as a template for the subsequent silica deposition. The silicification at close to neutral pH is spatially restricted to the localized polyamine and consequently to the fiber surface. In case of the linear poly(ethylenimine, silica shells of several micrometers in thickness can be obtained and their morphology is easily controlled by a considerable number of synthesis parameters. A unique feature is the hierarchical biomimetic structure of the silica coating which surrounds the embedded carbon fiber by fibrillar and interconnected silica fine-structures. The high surface area of the nanostructured composite fiber may be exploited for catalytic applications and adsorption purposes.

  1. Structural and Chemical Characterization of Silica Spheres before and after Modification by Silanization for Trypsin Immobilization

    Directory of Open Access Journals (Sweden)

    Eduardo F. Barbosa

    2017-01-01

    Full Text Available In the last decades, silica particles of a variety of sizes and shapes have been characterized and chemically modified for several applications, from chromatographic separation to dental supplies. The present study proposes the use of aminopropyl triethoxysilane (APTS silanized silica particles to immobilize the proteolytic enzyme trypsin for the development of a bioreactor. The major advantage of the process is that it enables the polypeptides hydrolysis interruption simply by removing the silica particles from the reaction bottle. Silanized silica surfaces showed significant morphological changes at micro- and nanoscale level. Chemical characterization showed changes in elemental composition, chemical environment, and thermal degradation. Their application as supports for trypsin immobilization showed high immobilization efficiency at reduced immobilization times, combined with more acidic conditions. Indirect immobilization quantification by reversed-phase ultrafast high performance liquid chromatography proved to be a suitable approach due to its high linearity and sensitivity. Immobilized trypsin activities on nonmodified and silanized silica showed promising features (e.g., selective hydrolysis for applications in proteins/peptides primary structure elucidation for proteomics. Silanized silica system produced some preferential targeting peptides, probably due to the hydrophobicity of the nanoenvironment conditioned by silanization.

  2. Electronic structure of semiconductor quantum films

    International Nuclear Information System (INIS)

    Zhang, S.B.; Yeh, C.; Zunger, A.

    1993-01-01

    The electronic structure of thin (≤30 A) free-standing ideal films of Si(001), Si(110), and GaAs(110) is calculated using a plane-wave pseudopotential description. Unlike the expectation based on the simple effective-mass model, we find the following. (i) The band gaps of (001) quantum films exhibit even-odd oscillation as a function of the number N of monolayers. (ii) In addition to sine-type envelope functions which vanish at the film boundaries, some states have cosine envelope functions with extrema at boundaries. (iii) Even-layer Si(001) films exhibit at the valence-band maximum a state whose energy does not vary with the film thickness. Such zero confinement states have constant envelope throughout the film. (iv) Optical transitions in films exhibit boundary-imposed selection rules. Furthermore, oscillator strengths for pseudodirect transitions in the vicinity of forbidden direct transitions can be enhanced by several orders of magnitude. These findings, obtained in direct supercell calculations, can be explained in terms of a truncated crystal (TC) analysis. In this approach the film's wave functions are expanded in terms of pairs of bulk wave functions exhibiting a destructive interference at the boundaries. This maps the eigenvalue spectra of a film onto the bulk band structure evaluated at special k points which satisfy the boundary conditions. We find that the TC representation reproduces accurately the above-mentioned results of direct diagonalization of the film's Hamiltonian. This provides a simple alternative to the effective-mass model and relates the properties of quantum structures to those of the bulk material

  3. Submicrometric gratings fabrication from photosensitive organo-silica-hafnia thin films elaborated by sol-gel processing

    Energy Technology Data Exchange (ETDEWEB)

    Franc, Janyce [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Barnier, Vincent, E-mail: barnier@emse.fr [Ecole Nationale Superieure des Mines, SMS-EMSE, CNRS:UMR 5146, LCG, F-42023 Saint-Etienne (France); Vocanson, Francis, E-mail: francis.vocanson@univ-st-etienne.fr [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Gamet, Emilie; Lesage, Maryline [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Jamon, Damien [Universite de Lyon, F-42023 Saint-Etienne (France); Laboratoire Claude Chappe, Telecom Saint-Etienne, 42000 Saint-Etienne Cedex 2 (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Jourlin, Yves [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France)

    2012-07-31

    The aim of this study is the elaboration of a high index sol-gel material in order to prepare submicrometric grating. The gratings were obtained after few seconds of UV exposure in one step using an organically modified silica-hafnia matrix. The chemical composition of thin films after UV and annealing treatments were studied using Fourier Transform Infrared Spectroscopy and X-Ray Photoelectron Spectroscopy. The study of optical properties revealed that the annealed films are transparent from 200 to 1000 nm and have a refractive index from 1.550 to 1.701 depending on the hafnium concentration. - Highlights: Black-Right-Pointing-Pointer Silica-hafnia matrix with high refractive index was prepared using sol-gel process. Black-Right-Pointing-Pointer Organic and inorganic networks formation of thin films was investigated. Black-Right-Pointing-Pointer Optical properties are influenced by annealing treatment and initial hafnium amount. Black-Right-Pointing-Pointer The use of high Si:Hf molar ratio can lead to a loss transmittance below 300 nm. Black-Right-Pointing-Pointer Submicrometric grating period can be prepared using a holographic method.

  4. Structural characterization of ZnO thin films grown on various substrates by pulsed laser deposition

    International Nuclear Information System (INIS)

    Novotný, M; Bulíř, J; Lančok, J; Čížek, J; Kužel, R; Connolly, J; McCarthy, E; Krishnamurthy, S; Mosnier, J-P; Anwand, W; Brauer, G

    2012-01-01

    ZnO thin films were grown by pulsed laser deposition on three different substrates: sapphire (0 0 0 1), MgO (1 0 0) and fused silica (FS). The structure and morphology of the films were characterized by x-ray diffraction and scanning electron microscopy and defect studies were carried out using slow positron implantation spectroscopy (SPIS). Films deposited on all substrates studied in this work exhibit the wurtzite ZnO structure and are characterized by an average crystallite size of 20-100 nm. However, strong differences in the microstructure of films deposited on various substrates were found. The ZnO films deposited on MgO and sapphire single-crystalline substrates exhibit local epitaxy, i.e. a well-defined relation between film crystallites and the substrate. Domains with different orientation relationships with the substrate were found in both films. On the other hand, the film deposited on the FS substrate exhibits fibre texture with random lateral orientation of crystallites. Extremely high compressive in-plane stress of σ ∼ 14 GPa was determined in the film deposited on the MgO substrate, while the film deposited on sapphire is virtually stress-free, and the film deposited on the FS substrate exhibits a tensile in-plane stress of σ ∼ 0.9 GPa. SPIS investigations revealed that the concentration of open-volume defects in the ZnO films is substantially higher than that in a bulk ZnO single crystal. Moreover, the ZnO films deposited on MgO and sapphire single-crystalline substrates exhibit a significantly higher density of defects than the film deposited on the amorphous FS substrate. (paper)

  5. Photoluminescence of Se-related oxygen deficient center in ion-implanted silica films

    International Nuclear Information System (INIS)

    Zatsepin, A.F.; Buntov, E.A.; Pustovarov, V.A.; Fitting, H.-J.

    2013-01-01

    The results of low-temperature time-resolved photoluminescence (PL) investigation of thin SiO 2 films implanted with Se + ions are presented. The films demonstrate an intensive PL band in the violet spectral region, which is attributed to the triplet luminescence of a new variant of selenium-related oxygen deficient center (ODC). The main peculiarity of the defect energy structure is the inefficient direct optical excitation. Comparison with spectral characteristics of isoelectronic Si-, Ge- and SnODCs show that the difference in electronic properties of the new center is related to ion size factor. It was established that the dominating triplet PL excitation under VUV light irradiation is related to the energy transfer from SiO 2 excitons. A possible model of Se-related ODC is considered. -- Highlights: • The low-temperature photoluminescence of thin SiO 2 films implanted with Se + ions was studied. • The 3.4 eV PL band was attributed to triplet luminescence of Se-related ODC. • The peculiarity of SeODC electronic properties is related to ion size factor. • The dominating VUV excitation of triplet PL is related to energy transfer from SiO 2 excitons. • A possible model of Se-related ODC is considered

  6. Structural Characterization of Silica Particles Extracted from Grass Stenotaphrum secundatum: Biotransformation via Annelids

    Directory of Open Access Journals (Sweden)

    A. Espíndola-Gonzalez

    2014-01-01

    Full Text Available This study shows the structural characterization of silica particles extracted from Stenotaphrum secundatum (St. Augustine grass using an annelid-based biotransformation process. This bioprocess starts when St. Augustine grass is turned into humus by vermicompost, and then goes through calcination and acid treatment to obtain silica particles. To determine the effect of the bioprocess, silica particles without biotransformation were extracted directly from the sample of grass. The characterization of the silica particles was performed using Infrared (FTIR and Raman spectroscopy, Transmission Electron Microscopy (TEM, X-ray Diffraction (XRD, Dynamic Light Scattering (DLS, and Energy Dispersion Spectroscopy (EDS. Both types of particles showed differences in morphology and size. The particles without biotransformation were essentially amorphous while those obtained via annelids showed specific crystalline phases. The biological relationship between the metabolisms of worms and microorganisms and the organic-mineral matter causes changes to the particles' properties. The results of this study are important because they will allow synthesis of silica in cheaper and more ecofriendly ways.

  7. Ordered and disordered evolution of the pore mesostructure in hybrid silica anti-reflective films obtained by one-pot self-assembly method

    Energy Technology Data Exchange (ETDEWEB)

    Ghazzal, Mohamed N., E-mail: g_nawfel@yahoo.fr; Debecker, Damien P.; Gaigneaux, Eric M.

    2016-07-29

    Hybrid mesoporous silica films were prepared in acid-catalysed medium using a one-pot self-assembly method. A gradual content of methyl groups was introduced into the inorganic framework by co-condensation of tetraethyl orthosilicate and methyltriethoxysilane. To better understand how the ordered and disordered transition occurs in mesoporous hybrid organosilica sytem as function of the MTES molar ratio in the starting solution, textural, chemical and optical properties of the films were studied by transmission electronic microscopy (TEM), grazing-incident small angle X-ray scattering (GISAXS), transmission Fourier transformed infrared (FTIR) and UV–visible spectroscopy. Increasing the loading of the incorporated organic groups (up to 40% in the starting solution) led simultaneously to a disorganization of the pore mesostructure and a reduction in the pore diameter. Concomitantly, a disordered domain of the silica rings in the walls was observed, which created bond strains in the silica wall contributing also to the disorganization of the pore mesostructure. Furthermore, an optimal MTES content was identified in order to obtain antireflection coatings, exhibiting low reflection in the visible range. - Highlights: • Mesoporous hybrid silica films where prepared by one-pot co-condensation of MTES and TEOS. • Ordered and disordered mesostructures were studied as function as variable MTES molar ratio. • A rearrangement of the silica cyclic species occurred as the molar ratio of MTES increases. • Transmittance of the silica coatings is affected by the MTES molar ratio.

  8. Thermally induced structural modifications and O2 trapping in highly porous silica nanoparticles

    International Nuclear Information System (INIS)

    Alessi, A.; Agnello, S.; Iovino, G.; Buscarino, G.; Melodia, E.G.; Cannas, M.; Gelardi, F.M.

    2014-01-01

    In this work we investigate by Raman spectroscopy the effect of isochronal (2 h) thermal treatments in air in the temperature range 200–1000 °C of amorphous silicon dioxide porous nanoparticles with diameters ranging from 5 up to 15 nm and specific surface 590–690 m 2 /g. Our results indicate that the amorphous structure changes similarly to other porous systems previously investigated, in fact superficial SiOH groups are removed, Si–O–Si linkages are created and the ring statistic is modified, furthermore these data evidence that the three membered rings do not contribute significantly to the Raman signal detected at about 495 cm −1 . In addition, after annealing at 900 and 1000 °C we noted the appearance of the O 2 emission at 1272 nm, absent in the not treated samples. The measure of the O 2 emission has been combined with electron paramagnetic resonance measurements of the γ irradiation induced HO · 2 radicals to investigate the O 2 content per mass unit of thin layers of silica. Our data reveal that the porous nanoparticles have a much lower ability to trap O 2 molecules per mass units than nonporous silica supporting a model by which O 2 trapping inside a surface layer of about 1 nm of silica is always limited. - Highlights: • O 2 emission and HO · 2 electron paramagnetic resonance signals are investigated. • Silica surface ability to trap O 2 molecules is explored by thermal treatments. • Raman study of thermally induced structural changes in porous silica nanoparticles. • Raman signal attributable to the three membered rings in silica

  9. Thermally induced structural modifications and O{sub 2} trapping in highly porous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, A., E-mail: antonino.alessi@unipa.it; Agnello, S.; Iovino, G.; Buscarino, G.; Melodia, E.G.; Cannas, M.; Gelardi, F.M.

    2014-12-15

    In this work we investigate by Raman spectroscopy the effect of isochronal (2 h) thermal treatments in air in the temperature range 200–1000 °C of amorphous silicon dioxide porous nanoparticles with diameters ranging from 5 up to 15 nm and specific surface 590–690 m{sup 2}/g. Our results indicate that the amorphous structure changes similarly to other porous systems previously investigated, in fact superficial SiOH groups are removed, Si–O–Si linkages are created and the ring statistic is modified, furthermore these data evidence that the three membered rings do not contribute significantly to the Raman signal detected at about 495 cm{sup −1}. In addition, after annealing at 900 and 1000 °C we noted the appearance of the O{sub 2} emission at 1272 nm, absent in the not treated samples. The measure of the O{sub 2} emission has been combined with electron paramagnetic resonance measurements of the γ irradiation induced HO{sup ·}{sub 2} radicals to investigate the O{sub 2} content per mass unit of thin layers of silica. Our data reveal that the porous nanoparticles have a much lower ability to trap O{sub 2} molecules per mass units than nonporous silica supporting a model by which O{sub 2} trapping inside a surface layer of about 1 nm of silica is always limited. - Highlights: • O{sub 2} emission and HO{sup ·}{sub 2} electron paramagnetic resonance signals are investigated. • Silica surface ability to trap O{sub 2} molecules is explored by thermal treatments. • Raman study of thermally induced structural changes in porous silica nanoparticles. • Raman signal attributable to the three membered rings in silica.

  10. Mesoporous silicas with covalently immobilized β-cyclodextrin moieties: synthesis, structure, and sorption properties

    Science.gov (United States)

    Roik, Nadiia V.; Belyakova, Lyudmila A.; Trofymchuk, Iryna M.; Dziazko, Marina O.; Oranska, Olena I.

    2017-09-01

    Mesoporous silicas with chemically attached macrocyclic moieties were successfully prepared by sol-gel condensation of tetraethyl orthosilicate and β-cyclodextrin-silane in the presence of a structure-directing agent. Introduction of β-cyclodextrin groups into the silica framework was confirmed by the results of IR spectral, thermogravimetric, and quantitative chemical analysis of surface compounds. The porous structure of the obtained materials was characterized by nitrogen adsorption-desorption measurements, powder X-ray diffraction, transmission electron microscopy, and dynamic light scattering. It was found that the composition of the reaction mixture used in β-cyclodextrin-silane synthesis significantly affects the structural parameters of the resulting silicas. The increase in (3-aminopropyl)triethoxysilane as well as the coupling agent content in relation to β-cyclodextrin leads ultimately to the lowering or complete loss of hexagonal arrangement of pore channels in the synthesized materials. Formation of hexagonally ordered mesoporous structure was observed at molar composition of the mixture 0.049 TEOS:0.001 β-CD-silane:0.007 CTMAB:0.27 NH4OH:7.2 H2O and equimolar ratio of components in β-CD-silane synthesis. The sorption of alizarin yellow on starting silica and synthesized materials with chemically attached β-cyclodextrin moieties was studied in phosphate buffer solutions with pH 7.0. Experimental results of the dye equilibrium sorption were analyzed using Langmuir, Freundlich, and Redlich-Peterson isotherm models. It was proved that the Redlich-Peterson isotherm model is the most appropriate for fitting the equilibrium sorption of alizarin yellow on parent silica with hexagonally arranged mesoporous structure as well as on modified one with chemically immobilized β-cyclodextrin groups. [Figure not available: see fulltext.

  11. Controlling pore morphology and properties of nanoporous silica films using the different architecture PS-b-P2VP as a template.

    Science.gov (United States)

    Yu, Yang-Yen; Chien, Wen-Chen; Chen, Shih-Ting

    2010-07-01

    Nanoporous silica films were prepared through the templating of amphiphilic block copolymer, poly(styrene-2-vinyl pyridine) (PS-b-P2VP), and monodispersed colloidal silica nanoparticles. The experimental and theoretical studies suggested that the intermolecular hydrogen bonding existes between the colloidal silica nanoparticles and PS-b-P2VP. The effects of the loading ratio and P2VP chain length on the morphology and properties of the prepared nanoporous silica films were investigated. TEM and AFM studies showed that the uniform pore size could be achieved and the pore size increased with increasing porogen loading. The refractive index and dielectric constant of the prepared nanoporous films decreased with an increase in PS-b-P2VP loading. On the other hand, the porosity increased with an increasing PS-b-P2VP loading. This study demonstrated a methodology to control pore morphology and properties of the nanoporous silica films through the templating of PS-b-P2VP.

  12. Fractal Structures on Silica Aerogels Containing Titanium: A Small Angle Neutron Scattering Study

    International Nuclear Information System (INIS)

    Widya Sari; Dian Fitriyani; Abdul Aziz Mohamed; Noordin Ibrahim

    2009-01-01

    Full text: The fractal structure of silica aerogels containing titanium has been investigated by means of small-angle neutron scattering (SANS) technique. The SANS experiments were conducted using a 36 meter SANS BATAN spectrometer (SMARTer) in Serpong, Indonesia in the range of momentum transfer Q, 0.006 -1 ) < 0.3. The power-law for a fractal object scattering Q-D observed from all measured samples. The Fourier transform of pattern I(Q) a pair correlation model function was implemented in analyzing the structure factor from the power-law scattering profiles. The results are showing that the silica aerogels containing titanium has a mass fractal where its dimension DM is larger than the pure silica aerogels. The mass fractal dimension of silica aerogels containing titanium is relatively constant between 2.23 to 2.40 with the decrease of acid concentrations during a sol-gel process and formed a nanometer size of aggregate. Those fractal structures were simulated using a Delphi language and the results are presented in this paper. (author)

  13. Laser ablation of toluene liquid for surface micro-structuring of silica glass

    International Nuclear Information System (INIS)

    Niino, H.; Kawaguchi, Y.; Sato, T.; Narazaki, A.; Gumpenberger, T.; Kurosaki, R.

    2006-01-01

    Microstructures with well-defined micropatterns were fabricated on the surfaces of silica glass using a laser-induced backside wet etching (LIBWE) method by diode-pumped solid state (DPSS) UV laser at the repetition rate of 10 kHz. For a demonstration of flexible rapid prototyping as mask-less exposure system, the focused laser beam was directed to the sample by galvanometer-based point scanning system. Additionally, a diagnostics study of plume propagation in the ablated products of toluene solid film was carried out with an intensified CCD (ICCD) camera

  14. Experimental collaboration for thick concrete structures with alkali-silica reaction

    Science.gov (United States)

    Ezell, N. Dianne Bull; Hayes, Nolan; Lenarduzzi, Roberto; Clayton, Dwight; Ma, Z. John; Le Pape, Sihem; Le Pape, Yann

    2018-04-01

    Alkali-Silica Reaction (ASR) is a reaction that occurs over time in concrete between alkaline cement paste and reactive, non-crystalline silica in aggregates. An expansive gel is formed within the aggregates which results in micro-cracks in aggregates and adjacent cement paste. The reaction requires the presence of water and has been predominantly detected in groundwater-impacted portions of below grade structures, with limited impact to exterior surfaces in above grade structures. ASR can potentially affect concrete properties and performance characteristics such as compressive strength, modulus of elasticity, shear strength, and tensile strength. Since ASR degradation often takes significant amounts of time, developing ASR detection techniques is important to the sustainability and extended operation lifetimes of nuclear power plants (NPPs). The University of Tennessee, Knoxville (UTK) in collaboration with Oak Ridge National Laboratory (ORNL) designed and built an experiment representative of typical NPP structures to study ASR in thick concrete structures.

  15. Fluctuations and structure of amphiphilic films

    International Nuclear Information System (INIS)

    Gourier, CH.

    1996-01-01

    This thesis is divided in three parts.The first part exposes in a theoretical point of view, how the fluctuations spectrum of an amphiphilic film is governed by its properties and its bidimensional characteristics.The measurements of fluctuations spectra of an interface are accessible with the measurement of intensity that interface diffuses out of the specular angle, we present in the second chapter the principles of the X rays diffusion by a real interface and see how the diffuse diffusion experiments allow to determine the fluctuations spectrum of an amphiphilic film. The second part is devoted to the different experimental techniques that have allowed to realize the study of fluctuation as well as the structural study.The third part is devoted to experimental results concerning the measurements of fluctuations spectra and to the study of the structure of amphiphilic films. We show that it is possible by using an intense source of X rays (ESRF: European Synchrotron Radiation Facility) to measure the water and amphiphilic films fluctuations spectra until molecular scales. The last chapter is devoted to the structural study and film fluctuations made of di-acetylenic molecules. (N.C.)

  16. The Structure and Properties of Silica Glass Nanostructures using Novel Computational Systems

    Science.gov (United States)

    Doblack, Benjamin N.

    The structure and properties of silica glass nanostructures are examined using computational methods in this work. Standard synthesis methods of silica and its associated material properties are first discussed in brief. A review of prior experiments on this amorphous material is also presented. Background and methodology for the simulation of mechanical tests on amorphous bulk silica and nanostructures are later presented. A new computational system for the accurate and fast simulation of silica glass is also presented, using an appropriate interatomic potential for this material within the open-source molecular dynamics computer program LAMMPS. This alternative computational method uses modern graphics processors, Nvidia CUDA technology and specialized scientific codes to overcome processing speed barriers common to traditional computing methods. In conjunction with a virtual reality system used to model select materials, this enhancement allows the addition of accelerated molecular dynamics simulation capability. The motivation is to provide a novel research environment which simultaneously allows visualization, simulation, modeling and analysis. The research goal of this project is to investigate the structure and size dependent mechanical properties of silica glass nanohelical structures under tensile MD conditions using the innovative computational system. Specifically, silica nanoribbons and nanosprings are evaluated which revealed unique size dependent elastic moduli when compared to the bulk material. For the nanoribbons, the tensile behavior differed widely between the models simulated, with distinct characteristic extended elastic regions. In the case of the nanosprings simulated, more clear trends are observed. In particular, larger nanospring wire cross-sectional radii (r) lead to larger Young's moduli, while larger helical diameters (2R) resulted in smaller Young's moduli. Structural transformations and theoretical models are also analyzed to identify

  17. Effect of various structure directing agents on the physicochemical properties of the silica aerogels prepared at an ambient pressure

    KAUST Repository

    Sarawade, Pradip; Shao, Godlistennamwel; Quang, Dangviet; Kim, Heetaik

    2013-01-01

    We studied the effects of various surfactants on the textural properties (BET surface area, pore size, and pore volume) of the silica aerogels prepared at an ambient pressure. A simple surface modification of silica gel prepared at an ambient pressure through hydrolysis and polycondensation of TEOS as asilica precursor was conducted using various structure directing agents. The treatment was found to induce a significant difference in the porosity of the silica aerogel. Highly porous silica aerogels with bimodal porous structures were prepared by modifying the surface of the silica wet-gel (alcogel) with trimethylchlorosilane (TMCS) in order to preserve its porosity. The samples were analyzed by small-angle X-ray scattering and nitrogen adsorption. In this work, a possible new type of highly porous hydrophobic silica aerogel with a bimodal porous structure is presented. A hydrophilic extremely porous (high surface area and large pore volume) silica aerogel was obtained by heating the as-synthesized hydrophobic silica aerogel at 400°C for 1 h. There was a significant effect of structure directing agent on the textural properties, such as specific surface area, pore size distribution and cumulative pore volume of the silicaaerogels. © 2013 Elsevier B.V. All rights reserved.

  18. Effect of various structure directing agents on the physicochemical properties of the silica aerogels prepared at an ambient pressure

    KAUST Repository

    Sarawade, Pradip

    2013-12-01

    We studied the effects of various surfactants on the textural properties (BET surface area, pore size, and pore volume) of the silica aerogels prepared at an ambient pressure. A simple surface modification of silica gel prepared at an ambient pressure through hydrolysis and polycondensation of TEOS as asilica precursor was conducted using various structure directing agents. The treatment was found to induce a significant difference in the porosity of the silica aerogel. Highly porous silica aerogels with bimodal porous structures were prepared by modifying the surface of the silica wet-gel (alcogel) with trimethylchlorosilane (TMCS) in order to preserve its porosity. The samples were analyzed by small-angle X-ray scattering and nitrogen adsorption. In this work, a possible new type of highly porous hydrophobic silica aerogel with a bimodal porous structure is presented. A hydrophilic extremely porous (high surface area and large pore volume) silica aerogel was obtained by heating the as-synthesized hydrophobic silica aerogel at 400°C for 1 h. There was a significant effect of structure directing agent on the textural properties, such as specific surface area, pore size distribution and cumulative pore volume of the silicaaerogels. © 2013 Elsevier B.V. All rights reserved.

  19. One-Pot Fabrication of Antireflective/Antibacterial Dual-Function Ag NP-Containing Mesoporous Silica Thin Films.

    Science.gov (United States)

    Wang, Kaikai; He, Junhui

    2018-04-04

    Thin films that integrate antireflective and antibacterial dual functions are not only scientifically interesting but also highly desired in many practical applications. Unfortunately, very few studies have been devoted to the preparation of thin films with both antireflective and antibacterial properties. In this study, mesoporous silica (MSiO 2 ) thin films with uniformly dispersed Ag nanoparticles (Ag NPs) were prepared through a one-pot process, which simultaneously shows high transmittance, excellent antibacterial activity, and mechanical robustness. The optimal thin-film-coated glass substrate demonstrates a maximum transmittance of 98.8% and an average transmittance of 97.1%, respectively, in the spectral range of 400-800 nm. The growth and multiplication of typical bacteria, Escherichia coli ( E. coli), were effectively inhibited on the coated glass. Pencil hardness test, tape adhesion test, and sponge washing test showed favorable mechanical robustness with 5H pencil hardness, 5A grade adhesion, and functional durability of the coating, which promises great potential for applications in various touch screens, windows for hygiene environments, and optical apparatuses for medical uses such as endoscope, and so on.

  20. Structural, optical and mechanical properties of amorphous and crystalline alumina thin films

    Energy Technology Data Exchange (ETDEWEB)

    Nayar, Priyanka [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Khanna, Atul, E-mail: akphysics@yahoo.com [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Kabiraj, D.; Abhilash, S.R. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Beake, Ben D.; Losset, Yannick [Micro Materials Limited, Unit 3, Wrexham Technology Park, Wrexham LL13 7YP (United Kingdom); Chen, Banghao [Chemistry and Biochemistry Department, Florida State University, Tallahassee 32306 (United States)

    2014-10-01

    Thin films of amorphous alumina of thickness 350 nm were deposited on fused silica substrates by electron beam evaporation. Amorphous films were annealed at several temperatures in the range: 400–1130 °C and changes in film crystallinity, short-range structure, optical and mechanical properties were studied. X-ray diffraction studies found that crystallization starts at 800 °C and produces γ and δ-alumina, the latter phase grows with heat treatment and the sample was mostly δ and θ-alumina after annealing at 1130 °C. The as-deposited amorphous alumina films have low hardness of 5 to 8 GPa, which increases to 11 to 12 GPa in crystalline sample. {sup 27}Al Magic Angle Spinning Nuclear Magnetic Resonance was used to study the short-range order of amorphous and crystalline alumina films and it was found that amorphous alumina film contains AlO{sub 5} and AlO{sub 4} structural units in the ratio of 1:2. The concentration of AlO{sub 5} was significantly suppressed in crystalline film, which contains 48% of Al{sup 3+} ions in AlO{sub 6}, 7% in AlO{sub 5} and 45% in AlO{sub 4} units. - Highlights: • Structure–property correlations in alumina films grown by electron-beam evaporation • Amorphous films crystallize into γ and δ-alumina on annealing in air at 800 °C. • δ and θ-alumina films are stable up to 1130 °C and do not transform to α-phase. • Amorphous alumina films contain {sup [5]}Al and {sup [4]}Al structural units in the ratio of 1:2. • {sup [5]}Al decreases whereas {sup [6]}Al concentration increases on crystallization.

  1. Engineering the internal structure of magnetic silica nanoparticles by thermal control

    KAUST Repository

    Song, Hyon Min; Zink, Jeffrey I.; Khashab, Niveen M.

    2014-01-01

    Calcination of hydrated iron salts in the pores of both spherical and rod-shaped mesoporous silica nanoparticles (NPs) changes the internal structure from an ordered 2D hexagonal structure into a smaller number of large voids in the particles with sizes ranging from large hollow cores down to ten nanometer voids. The voids only form when the heating rate is rapid at a rate of 30 °C min-1. The sizes of the voids are controlled reproducibly by the final calcination temperature; as the temperature is decreased the number of voids decreases as their size increases. The phase of the iron oxide NPs is α-Fe2O3 when annealed at 500 °C, and Fe3O4 when annealed at lower temperatures. The water molecules in the hydrated iron (III) chloride precursor salts appear to play important roles by hydrolyzing Si-O-Si bonding, and the resulting silanol is mobile enough to affect the reconstruction into the framed hollow structures at high temperature. Along with hexahydrates, trivalent Fe3+ ions are assumed to contribute to the structure disruption of mesoporous silica by replacing tetrahedral Si4+ ions and making Fe-O-Si bonding. Volume fraction tomography images generated from transmission electron microscopy (TEM) images enable precise visualization of the structures. These results provide a controllable method of engineering the internal shapes in silica matrices containing superparamagnetic NPs.

  2. Engineering the internal structure of magnetic silica nanoparticles by thermal control

    KAUST Repository

    Song, Hyon Min

    2014-09-30

    Calcination of hydrated iron salts in the pores of both spherical and rod-shaped mesoporous silica nanoparticles (NPs) changes the internal structure from an ordered 2D hexagonal structure into a smaller number of large voids in the particles with sizes ranging from large hollow cores down to ten nanometer voids. The voids only form when the heating rate is rapid at a rate of 30 °C min-1. The sizes of the voids are controlled reproducibly by the final calcination temperature; as the temperature is decreased the number of voids decreases as their size increases. The phase of the iron oxide NPs is α-Fe2O3 when annealed at 500 °C, and Fe3O4 when annealed at lower temperatures. The water molecules in the hydrated iron (III) chloride precursor salts appear to play important roles by hydrolyzing Si-O-Si bonding, and the resulting silanol is mobile enough to affect the reconstruction into the framed hollow structures at high temperature. Along with hexahydrates, trivalent Fe3+ ions are assumed to contribute to the structure disruption of mesoporous silica by replacing tetrahedral Si4+ ions and making Fe-O-Si bonding. Volume fraction tomography images generated from transmission electron microscopy (TEM) images enable precise visualization of the structures. These results provide a controllable method of engineering the internal shapes in silica matrices containing superparamagnetic NPs.

  3. Sol-gel approach to the novel organic-inorganic hybrid composite films with ternary europium complex covalently bonded with silica matrix

    International Nuclear Information System (INIS)

    Dong Dewen; Yang Yongsheng; Jiang Bingzheng

    2006-01-01

    Novel organic-inorganic hybrid composite films with ternary lanthanide complex covalently bonded with silica matrix were prepared in situ via co-ordination of N-(3-propyltriethoxysilane)-4-carboxyphthalimide (TAT) and 1,10-phenanthroline (Phen) with europium ion (Eu 3+ ) during a sol-gel approach and characterized by the means of spectrofluorimeter, phosphorimeter and infrared spectrophotometer (FTIR). The resulting transparent films showed improved photophysical properties, i.e. increased luminescence intensity and longer luminescence lifetime, compared with the corresponding binary composite films without Phen. All the results revealed that the intense luminescence of the composite film was attributed to the efficient energy transfer from ligands, especially Phen, to chelated Eu 3+ and the reduced non-radiation through the rigid silica matrix and 'site isolation'

  4. Preparation and characterization of silica/fluorinated acrylate copolymers hybrid films and the investigation of their icephobicity

    International Nuclear Information System (INIS)

    Huang Yanfen; Hu Mingjie; Yi Shengping; Liu Xinghai; Li Houbin; Huang Chi; Luo Yunbai; Li Yan

    2012-01-01

    Inexpensive hydrophobic and icephobic coatings and films were obtained by a simple method. These coatings were prepared by mixing silica sol and fluorinated acrylate copolymers. There was a phase separation process in the film-forming which can provide the excellent performance. Small amount (about 2 wt.%) of fluorinated (methyl) acrylate was used in all of these coatings. The coatings were eco-friendly by using ethanol as the solvent system. Scanning electron microscopy, atomic force microscope, energy dispersive X-ray fluorescence spectrometer, water contact angle, thermal gravimetric analysis and tests of adhesion and hardness had been performed to characterize the morphological feature, chemical composition, hydrophobicity and icephobicity of the surface, thermal stability and mechanical properties of the coatings. The results showed that the films had good hydrophobicity, high thermal stability and excellent mechanical properties of adhesion strength and pencil hardness. Furthermore, by testing their properties of delaying water droplet from icing, it was found that ice formation was delayed for 90 min compared with the glass surface at − 5.6 °C. The hybrid coatings may be suitable for large-scale and practical application owing to its flexibility and simplicity. - Highlights: ► Coatings were prepared by mixing fluorinated acrylate copolymer and silica. ► Mechanical properties and anti-icing performance of the coatings were examined. ► Water contact angle increased with raising SiO 2 (sol)/monomers weight ratio. ► Ice formation was delayed for 90 min at − 5.6 °C.

  5. Successful implementation of the stepwise layer-by-layer growth of MOF thin films on confined surfaces: Mesoporous silica foam as a first case study

    KAUST Repository

    Shekhah, Osama; Fu, Lei; Sougrat, Rachid; Belmabkhout, Youssef; Cairns, Amy; Giannelis, Emmanuel P.; Eddaoudi, Mohamed

    2012-01-01

    Here we report the successful growth of highly crystalline homogeneous MOF thin films of HKUST-1 and ZIF-8 on mesoporous silica foam, by employing a layer-by-layer (LBL) method. The ability to control and direct the growth of MOF thin films on confined surfaces, using the stepwise LBL method, paves the way for new prospective applications of such hybrid systems. © 2012 The Royal Society of Chemistry.

  6. Organic-inorganic nanocomposite films made from polyurethane dispersions and colloidal silica particles

    Czech Academy of Sciences Publication Activity Database

    Serkis, Magdalena; Špírková, Milena; Kredatusová, Jana; Hodan, Jiří; Bureš, R.

    2016-01-01

    Roč. 23, č. 2 (2016), s. 157-173 ISSN 0927-6440 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane dispersion * colloidal silica * composites Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.083, year: 2016

  7. Preparation and characterization of bimetallic catalysts supported on mesoporous silica films

    NARCIS (Netherlands)

    Muraza, O.; Rebrov, E.V.; Khimyak, T.; Johnson, B.F.G.; Kooyman, P.J.; Lafont, U.; Albouy, P.A.; Croon, de M.H.J.M.; Schouten, J.C.

    2006-01-01

    Thin (300–1000 nm) mesoporous silica coatings with hexagonal and cubic mesostructure have been prepared on Pyrex® 7740 borosilicate glass substrates by the evaporation induced self assembly assisted sol-gel route. Prior to the synthesis, a 50 nm TiO2 layer has been deposited on the substate by

  8. Investigation of structural integrity for turbine generator foundation affected by alkali-silica reaction

    International Nuclear Information System (INIS)

    Ryo Fujimoto; Hiroshi Shimizu; Hisashi Sekimoto; Yuichi Watanabe; Tatsuya Ishikawa

    2005-01-01

    Turbine Generator Foundation is a reinforced concrete structure having a table deck to support equipments and columns to support the table deck. After operation of the plant, the expansion of the table deck in turbine longitudinal axis in the structure has been observed. By investigation of concrete material property, it is found that the expansion has been caused by alkali-silica reaction (ASR). In this study, we evaluate the material properties of the structure affected by ASR and safety margin of capacity of the structure by nonlinear analysis using beam element model with those material properties. (authors)

  9. Fabrication of semi-transparent superoleophobic thin film from fabrics and nanoparticle-based hierarchical structure

    Directory of Open Access Journals (Sweden)

    Nishizawa S.

    2013-08-01

    Full Text Available Superoleophobic thin films have many potential applications including fluid transfer, fluid power systems, stain resistant and antifouling materials, and microfluidics among others. Transparency is also desired with superhydrophobicity for their numerous applications; however transparency and oleophobicity are almost incompatible relationship with each other in the point of surface structure. Because oleophobicity required rougher structure at nano-micro scale than hydrophobicity, and these rough structure brings light scattering. So far, there is very few report of the compatible of transparency and superoleophobicity. In this report, we proposed the see-through type fabrics using the nanoparticle-based hierarchical structure thin film for improving both of oleophobicity and transparency. The vacant space between fibrils of fabrics has two important roles: the one is to through the light, another one is to introduce air layer to realize Cassie state of liquid droplet on thin film. To realize the low surface energy and nanoscale rough structure surface on fibrils, we used the spray method with perfluoroalkyl methacrylic copolymer (PMC, silica nano particles and volatile solvent. From the SEM image, the hierarchical structures of nanoparticle were formed uniformly on the fabrics. The transparency of thin film obtained was approximately 61% and the change of transparency between pre-coated fabrics and coated was 11%. From investigation of the surface wettability, the contact angles of oils (rapeseed oil and hexadecane and water droplet on the fabricated film were over 150 degree.

  10. Silica in situ enhanced PVA/chitosan biodegradable films for food packages.

    Science.gov (United States)

    Yu, Zhen; Li, Baoqiang; Chu, Jiayu; Zhang, Peifeng

    2018-03-15

    Non-degradable plastic food packages threaten the security of environment. The cost-effective and biodegradable polymer films with good mechanical properties and low permeability are very important for food packages. Among of biodegradable polymers, PVA/chitosan (CS) biodegradable films have attracted considerable attention because of feasible film forming ability. However, PVA/CS biodegradable films suffered from poor mechanical properties. To improve mechanical properties of PVA/CS biodegradable films, we developed SiO 2 in situ to enhance PVA/CS biodegradable films via hydrolysis of sodium metasilicate in presence of PVA and chitosan solution. The tensile strength of PVA/CS biodegradable films was improved 45% when 0.6 wt.% SiO 2 was incorporated into the films. Weight loss of PVA/CS biodegradable films was 60% after 30 days in the soil. The permeability of oxygen and moisture of PVA/CS biodegradable films was reduced by 25.6% and 10.2%, respectively. SiO 2 in situ enhanced PVA/CS biodegradable films possessed not only excellent mechanical properties, but also barrier of oxygen and water for food packages to extend the perseveration time. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Silica artificial opal incorporated with silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Li Wenjiang, E-mail: wjli@zju.edu.cn [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China); Sun Tan [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China)

    2009-07-15

    The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

  12. Silica artificial opal incorporated with silver nanoparticles

    International Nuclear Information System (INIS)

    Li Wenjiang; Sun Tan

    2009-01-01

    The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

  13. Facile and tunable synthesis of hierarchical mesoporous silica materials ranging from flower structure with wrinkled edges to hollow structure with coarse surface

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Nanjing, E-mail: nanjing.hao@dartmouth.edu [Dartmouth College, Thayer School of Engineering (United States); Li, Laifeng; Tang, Fangqiong, E-mail: tangfq@mail.ipc.ac.cn [Chinese Academy of Sciences, Technical Institute of Physics and Chemistry (China)

    2016-11-15

    Mesoporous silica materials have attracted great attention in many fields. However, facile and tunable synthesis of hierarchical mesoporous silica structures is still a big challenge, and thus the development of them still lags behind. Herein, well-defined mesoporous silica flower structure with wrinkled edges and mesoporous silica hollow structure with coarse surface were synthesized simply by using poly(vinylpyrrolidone) and hexadecylamine as cotemplates in different water/ethanol solvent systems. The shape evolution from flower to hollow can be easily realized by tuning the volume ratio of water to ethanol, and the yields of both materials can reach gram scale. The formation mechanisms of mesoporous silica flower and hollow structures were also experimentally investigated and discussed. These novel hierarchical structures having unique physicochemical properties may bring many interesting insights into scientific research and technological application.

  14. Evidence of coexistence of micro and nanoporosity of organo-silica polymeric films deposited on silicon by plasma deposition

    International Nuclear Information System (INIS)

    Purohit, Viswas; Mielczarski, Ela; Mielczarski, Jerzy A.; Akesso, Laurent

    2013-01-01

    A range of hybrid, SiOCH films were deposited on silicon substrates within a radio frequency plasma reactor using hexamethyldisiloxane (HMDSO) as a precursor. The plasma polymerized films were deposited at various HMDSO/argon/oxygen ratios. The composition and structure, at microscopic and nanoscopic levels, of the deposited films were determined by external reflection and transmission Fourier Transform Infrared (FTIR) spectroscopy as well as by X-Ray Photoelectron Spectroscopy (XPS). The content of carbon and oxygen in films were found to be inversely proportional to each other. XPS results showed that the outermost surface of the deposited films are nanoporous and coexist with microporosity which was revealed by electron microscopy. The structure of deposited coatings is anisotropic as was documented by polarized external reflection FTIR spectroscopy. Several correlations between the film chemical composition, surface structure, and macroscopic properties of the films such as: hydrophobicity and hydrophilicity were established. - Highlights: • Hybrid organo-polymer silicon films deposited by RF plasma on silicon substrates. • FTIR and XPS reveal porosity by interpreting bonding between Si and –O. • Quantification of nano and microporosity are identified with bonding of Si with –O

  15. Evidence of coexistence of micro and nanoporosity of organo-silica polymeric films deposited on silicon by plasma deposition

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, Viswas, E-mail: vishwas.purohit@gmail.com [Laboratoire Environnment et Mineralurgie, UMR 7569 CNRS, INPL-ENSG, BP.40, 54501 Vandoeuvre-les-Nancy (France); Mielczarski, Ela; Mielczarski, Jerzy A. [Laboratoire Environnment et Mineralurgie, UMR 7569 CNRS, INPL-ENSG, BP.40, 54501 Vandoeuvre-les-Nancy (France); Akesso, Laurent [Teer Coatings Ltd., Droitwich, Worcestershire WR9 9AS (United Kingdom)

    2013-09-16

    A range of hybrid, SiOCH films were deposited on silicon substrates within a radio frequency plasma reactor using hexamethyldisiloxane (HMDSO) as a precursor. The plasma polymerized films were deposited at various HMDSO/argon/oxygen ratios. The composition and structure, at microscopic and nanoscopic levels, of the deposited films were determined by external reflection and transmission Fourier Transform Infrared (FTIR) spectroscopy as well as by X-Ray Photoelectron Spectroscopy (XPS). The content of carbon and oxygen in films were found to be inversely proportional to each other. XPS results showed that the outermost surface of the deposited films are nanoporous and coexist with microporosity which was revealed by electron microscopy. The structure of deposited coatings is anisotropic as was documented by polarized external reflection FTIR spectroscopy. Several correlations between the film chemical composition, surface structure, and macroscopic properties of the films such as: hydrophobicity and hydrophilicity were established. - Highlights: • Hybrid organo-polymer silicon films deposited by RF plasma on silicon substrates. • FTIR and XPS reveal porosity by interpreting bonding between Si and –O. • Quantification of nano and microporosity are identified with bonding of Si with –O.

  16. Influence of acetone extract from natural rubber on the structure and interface interaction in NR/silica composites

    Science.gov (United States)

    Xu, Tiwen; Jia, Zhixin; Wu, Lianghui; Chen, Yongjun; Luo, Yuanfang; Jia, Demin; Peng, Zheng

    2017-11-01

    It is well known that the coupling reagents as the additional modifiers were often used to improve the reinforcement effect of silica filled natural rubber. Actually, the commercial raw NR is a mixture consisting of polyisoprene and non-isoprene, where the latter one might have impact on the properties of NR/silica composites as an inartificial modifier inside. Thus, investigating the effect of non-isoprene compounds on the structure and properties of NR/silica composites is a novel approach to disclose the peculiarity of NR, which is meaningful to the assessment of NR quality. In this paper, the influences of acetone extract (AE) from natural rubber on the structure and mechanical properties of NR/silica composites were studied. Then the interfacial interactions between AE and silica were also illustrated through Fourier transform infrared spectroscopy (FTIR), thermogravimetic analysis (TGA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Results demonstrated the existence of hydrogen bond between silica and AE, also the covalent bond induced by esterification reaction between sbnd COOH and Sisbnd OH, which resulted in an increase of constrained regions around silica surface leading to the promotions on mechanical and dynamical properties of NR/silica composites significantly.

  17. Silica-gel structural characterization during the initial phases of gelation and drying

    International Nuclear Information System (INIS)

    Ferreira, Max Passos

    1996-01-01

    For centuries, glasses and ceramics have been made via melting or solid state reactions at temperatures above 100 deg C. The sol-gel process offers new approaches to the synthesis of glasses and ceramics, combining control of composition and structure at the molecular level with the ability to shape materials in bulk, powder, fiber and thin-film forms. The growth of sol-gel technology research is due to the many unique features of that class of materials. Major applications include optical elements and integrated optical devices, ceramic filters, membranes, supercondutors, magnetic, catalytic and manostructured materials to antioxidant, anticorrosion coatings and composite and biomedical materials. In this work a variety of techniques like spectroscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, light scattering nuclear magnetic resonance, X ray diffraction and nitrogen adsorption have been employed to investigate the initial phase of the sol-gel transition of gamma ray irradiated tetramethoxysilane (TMOS) solutions and non-irradiated TMOS solution and to get information about the structure of the silica gels obtained under different gelation conditions. Typically the tetramethoxysilane solutions were prepared using a molar ratio of TMOS to demineralized water of 1 to 16. Some experiments were made under catalysed conditions. The mixing was carried out at room temperature. The turbidity and light scattering experiments on the polycondensation of tetramethoxysilane show that exists no drastic difference in the gelling time of a gamma ray irradiated and a non-irradiated TMOS+H 2 O (1+16 M) solution. In the absence of a catalyst, the gelling time for both reactions occurs in about 3.30 h. When HNO 3 (o.03 M) was used, the gelling time observed was 3 days. Raman and ultraviolet-visible spectroscopy show no drastic difference during the initial phase at the sol-gel transition under ambient temperature/pressure and under gamma radiation. The gels heated

  18. Effect of adjustable molecular chain structure and pure silica zeolite nanoparticles on thermal, mechanical, dielectric, UV-shielding and hydrophobic properties of fluorinated copolyimide composites

    Science.gov (United States)

    Li, Qing; Liao, Guangfu; Zhang, Shulai; Pang, Long; Tong, Hao; Zhao, Wenzhe; Xu, Zushun

    2018-01-01

    A series of polyimide (PI) films, polyimide/pure silica zeolite nanoparticles (PSZN) blend films and polyimide/amine-functionalized pure silica zeolite nanoparticles (APSZN) composite films were successfully prepared by random copolycondensation. Thereinto, PSZN were synthesized by hydrothermal method. The polyimides were derived from 4,4‧-diaminodiphenyl ether (ODA), and three adjustable molar ratios (3:1, 1:1, 1:3) of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl] propane dianhydride (BPADA) and 4,4‧-(hexafluoroisopropylidene) diphthalic anhydride (6FDA). The effects of PSZN, APSZN and different chain structure on PI films were specifically evaluated in terms of morphology, thermal, mechanical, dielectric and UV-shielding properties, etc. Comparison was given among pure PI flims, PI/PSZN blend films and PI/APSZN composite flims. The results showed that the thermal and mechanical properties of PI films were drastically impaired after adding PSZN. On the contrary, the strength, toughness and thermal stability were improved after adding APSZN. Moreover, the dielectric constants of the PI/APSZN composite flims were lowered but UV-shielding properties were enhanced. Interestingly, we found that the greatest effects were obtained through introducing APSZN in PI derived by the 1:1 ratio of BPADA:6FDA. The corresponding PI/APSZN composite flim exhibited the most reinforced and toughened properties, the largest decrement of dielectric constant and the best UV-shielding efficiency, which made the composite flim be used as ultraviolet shielding material in outer space filled with high temperature and intensive ultraviolet light. Meanwhile, this work also provided a facile way to synthesize composite materials with adjustable performance.

  19. Three-dimensional structure of Au nanoparticles supported on amorphous silica and carbon substrates

    International Nuclear Information System (INIS)

    Bruma, A; Li, Z Y

    2012-01-01

    Scanning Transmission Electron Microscope (STEM) has been employed to study the three-dimensional structure of gold (Au) nanoparticles deposited by means of thermal evaporation in high vacuum on amorphous silica (a-SiO 2 ) and amorphous carbon (a-C) supports. By performing quantitative analysis on the evolution of the high angle annular dark field (HAADF) images, we studied the influence of the nature and the temperature of support on the growth mode of gold nanoparticles.

  20. Well-defined azazirconacyclopropane complexes supported on silica structurally determined by 2D NMR comparative elucidation

    KAUST Repository

    El Eter, Mohamad; Hamzaoui, Bilel; Abou-Hamad, Edy; Pelletier, Jeremie; Basset, Jean-Marie

    2013-01-01

    Grafting of Zr(NMe2)4 on mesoporous silica SBA-15 afforded selectively well-defined surface species SiOZr(NMe2) (η2NMeCH2). 2D solid-state NMR (1H- 13C HETCOR, Multiple Quantum) experiments have shown a unique structural rearrangement occurring on the immobilised zirconium bis methylamido ligand. © The Royal Society of Chemistry 2013.

  1. Biomimetic synthesized chiral mesoporous silica: Structures and controlled release functions as drug carrier

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jing; Xu, Lu, E-mail: xl2013109@163.com; Yang, Baixue; Bao, Zhihong; Pan, Weisan; Li, Sanming, E-mail: li_sanming2013@163.com

    2015-10-01

    This work initially illustrated the formation mechanism of chiral mesoporous silica (CMS) in a brand new insight named biomimetic synthesis. Three kinds of biomimetic synthesized CMS (B-CMS, including B-CMS1, B-CMS2 and B-CMS3) were prepared using different pH or stirring rate condition, and their characteristics were tested with transmission electron microscope and small angle X-ray diffraction. The model drug indomethacin was loaded into B-CMS and drug loading content was measured using ultraviolet spectroscopy. The result suggested that pH condition influenced energetics of self-assembly process, mainly packing energetics of the surfactant, while stirring rate was the more dominant factor to determine particle length. In application, indomethacin loading content was measured to be 35.3%, 34.8% and 35.1% for indomethacin loaded B-CMS1, indomethacin loaded B-CMS2 and indomethacin loaded B-CMS3. After loading indomethacin into B-CMS carriers, surface area, pore volume and pore diameter of B-CMS carriers were reduced. B-CMS converted crystalline state of indomethacin to amorphous state, leading to the improved indomethacin dissolution. B-CMS1 controlled drug release without burst-release, while B-CMS2 and B-CMS3 released indomethacin faster than B-CMS1, demonstrating that the particle length, the ordered lever of multiple helixes, the curvature degree of helical channels and pore diameter greatly contributed to the release behavior of indomethacin loaded B-CMS. - Highlights: • Chiral mesoporous silica was synthesized using biomimetic method. • pH influenced energetics of self-assembly process of chiral mesoporous silica. • Stirring rate determined the particle length of chiral mesoporous silica. • Controlled release behaviors of chiral mesoporous silica varied based on structures.

  2. Biomimetic synthesized chiral mesoporous silica: Structures and controlled release functions as drug carrier

    International Nuclear Information System (INIS)

    Li, Jing; Xu, Lu; Yang, Baixue; Bao, Zhihong; Pan, Weisan; Li, Sanming

    2015-01-01

    This work initially illustrated the formation mechanism of chiral mesoporous silica (CMS) in a brand new insight named biomimetic synthesis. Three kinds of biomimetic synthesized CMS (B-CMS, including B-CMS1, B-CMS2 and B-CMS3) were prepared using different pH or stirring rate condition, and their characteristics were tested with transmission electron microscope and small angle X-ray diffraction. The model drug indomethacin was loaded into B-CMS and drug loading content was measured using ultraviolet spectroscopy. The result suggested that pH condition influenced energetics of self-assembly process, mainly packing energetics of the surfactant, while stirring rate was the more dominant factor to determine particle length. In application, indomethacin loading content was measured to be 35.3%, 34.8% and 35.1% for indomethacin loaded B-CMS1, indomethacin loaded B-CMS2 and indomethacin loaded B-CMS3. After loading indomethacin into B-CMS carriers, surface area, pore volume and pore diameter of B-CMS carriers were reduced. B-CMS converted crystalline state of indomethacin to amorphous state, leading to the improved indomethacin dissolution. B-CMS1 controlled drug release without burst-release, while B-CMS2 and B-CMS3 released indomethacin faster than B-CMS1, demonstrating that the particle length, the ordered lever of multiple helixes, the curvature degree of helical channels and pore diameter greatly contributed to the release behavior of indomethacin loaded B-CMS. - Highlights: • Chiral mesoporous silica was synthesized using biomimetic method. • pH influenced energetics of self-assembly process of chiral mesoporous silica. • Stirring rate determined the particle length of chiral mesoporous silica. • Controlled release behaviors of chiral mesoporous silica varied based on structures

  3. Fabrication of Mesoporous Silica/Alumina Hybrid Membrane Film Nanocomposites using Template Sol-Gel Synthesis of Amphiphilic Triphenylene

    Science.gov (United States)

    Lintang, H. O.; Jalani, M. A.; Yuliati, L.; Salleh, M. M.

    2017-05-01

    Herein we reported that by introducing a one-dimensional (1D) substrate with a porous structure such as anodic aluminum oxide (AAO) membrane, mesoporous silica/alumina hybrid nanocomposites were successfully fabricated by using amphiphilic triphenylene (TPC10TEG) as a template in sol-gel synthesis (TPC10TEG/silicahex). For the optical study of the nanocomposites, TPC10TEG/silicahex showed absorption peak at 264 nm due to the ordered and long-range π-π stacking of the disc-like aromatic triphenylene core. Moreover, the hexagonal arrangement of TPC10TEG/silicahex was proven based on their diffraction peaks of d 100 and d 200 at 2θ = 2.52° and 5.04° and images of transmission electron microscopy (TEM), respectively. For fabrication of mesoporous silica/alumina hybrid membrane, TPC10TEG/silicahex was drop-casted onto AAO membrane for penetration into the porous structure via gravity. X-ray diffraction (XRD) analysis on the resulted hybrid nanocomposites showed that the diffraction peaks of d 100 and d 200 of TPC10TEG/silicahex were still preserved, indicating that the hexagonal arrangements of mesoporous silica were maintained even on AAO substrate. The morphology study on the hybrid nanocomposites using TEM, scanning electron microscope (SEM) and field emission scanning electron microscope (FE-SEM) showed the successful filling of most AAO channels with the TPC10TEG/silicahex nanocomposites.

  4. Adsorption-Induced Deformation of Hierarchically Structured Mesoporous Silica-Effect of Pore-Level Anisotropy.

    Science.gov (United States)

    Balzer, Christian; Waag, Anna M; Gehret, Stefan; Reichenauer, Gudrun; Putz, Florian; Hüsing, Nicola; Paris, Oskar; Bernstein, Noam; Gor, Gennady Y; Neimark, Alexander V

    2017-06-06

    The goal of this work is to understand adsorption-induced deformation of hierarchically structured porous silica exhibiting well-defined cylindrical mesopores. For this purpose, we performed an in situ dilatometry measurement on a calcined and sintered monolithic silica sample during the adsorption of N 2 at 77 K. To analyze the experimental data, we extended the adsorption stress model to account for the anisotropy of cylindrical mesopores, i.e., we explicitly derived the adsorption stress tensor components in the axial and radial direction of the pore. For quantitative predictions of stresses and strains, we applied the theoretical framework of Derjaguin, Broekhoff, and de Boer for adsorption in mesopores and two mechanical models of silica rods with axially aligned pore channels: an idealized cylindrical tube model, which can be described analytically, and an ordered hexagonal array of cylindrical mesopores, whose mechanical response to adsorption stress was evaluated by 3D finite element calculations. The adsorption-induced strains predicted by both mechanical models are in good quantitative agreement making the cylindrical tube the preferable model for adsorption-induced strains due to its simple analytical nature. The theoretical results are compared with the in situ dilatometry data on a hierarchically structured silica monolith composed by a network of mesoporous struts of MCM-41 type morphology. Analyzing the experimental adsorption and strain data with the proposed theoretical framework, we find the adsorption-induced deformation of the monolithic sample being reasonably described by a superposition of axial and radial strains calculated on the mesopore level. The structural and mechanical parameters obtained from the model are in good agreement with expectations from independent measurements and literature, respectively.

  5. Alkali passivation mechanism of sol-gel derived TiO2-SiO2 films coated on soda-lime-silica glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, A; Matsuno, Y; Katayama, S; Tsuno, T [Nippon Steel Glass Co. Ltd., Tokyo (Japan); Toge, N; Minami, T [University of Osaka Prefecture, Osaka (Japan). College of Engineering

    1992-09-01

    TiO2-SiO2 films prepared by the sol-gel method serves as an effective alkali passivation layer on a soda-lime-silica glass substrate and the film is superior to a sol-gel derived pure SiO2 film from the view point of weathering resistance improvement. To clarify the reason, alkali passivation mechanism of sol-gel derived TiO2-SiO2 glass films with different TiO2 contents coated on a soda-lime-silica glass substrate was studied by SIMS (secondary ion mass spectroscopy) and XPS (X-ray photoelectron spectroscopy) analyses, and compared with the results of a sol-gel derived pure SiO2 film. As a result, the following conclusions were obtained: An increase in TiO2 content in the TiO2 SiO2 film increases the sodium concentration in the film, which was induced by sodium migration from the glass substrate during the heat-treatment. Because of the presence of sodium the TiO2 -SiO2 films serve not as a barrier but as an effective getter of alkali ions and thereby effectively improve the weathering resistance Of the glass substrate. 10 refs., 6 figs.

  6. Perhydropolysilazane-derived silica-polymethylmethacrylate hybrid thin films highly doped with spiropyran: Effects of polymethylmethacrylate on the hardness, chemical durability and photochromic properties

    International Nuclear Information System (INIS)

    Yamano, Akihiro; Kozuka, Hiromitsu

    2011-01-01

    Polymethylmethacrylate (PMMA)-perhydropolysilazane (PHPS) hybrid thin films doped with spiropyran were prepared by spin-coating, which were then converted into 0.26-1.7 μm thick, spiropyran-doped PMMA-silica hybrid films by exposure treatment over aqueous ammonia. The spiropyran/(spiropyran + PHPS + PMMA) mass ratio was fixed at a high value of 0.2 so that the films exhibit visual photochromic changes in color, while the PMMA/(PMMA + PHPS) mass ratio, r, was varied. The spiropyran molecules in the as-prepared films were in merocyanine (MC) and spiro (SP) forms, with and without an optical absorption at 500 nm, at low (r ≤ 0.2) and high (r ≥ 0.4) PMMA contents, respectively. When PMMA content r was increased from 0 to 0.2, the degree of the MC-to-SP conversion on vis light illumination was enhanced, while at higher r's the spiropyran molecules underwent photodegradation. When the silica film (r = 0) was soaked in xylene under vis light, the spiropyran molecules were almost totally leached out, while not on soaking in the dark. On the other hand, no leaching occurred for the film of r = 0.2 either in the presence or absence of vis light. These suggest that the introduction of PMMA is effective in improving the chemical durability of the films, while the silica film (r = 0) is an interesting material with a photoresponsive controlled-release ability. The pencil hardness of the films decreased with increasing PMMA content, but remained over 9H at r ≤ 0.4.

  7. Nano-structured silica coated mesoporous carbon micro-granules for potential application in water filtration

    Science.gov (United States)

    Das, Avik; Sen, D.; Mazumder, S.; Ghosh, A. K.

    2017-05-01

    A novel nano-composite spherical micro-granule has been synthesized using a facile technique of solvent evaporation induced assembly of nanoparticles for potential application in water filtration. The spherical micro-granule is comprised of nano-structured shell of hydrophilic silica encapsulating a hydrophobic mesoporous carbon at the core. Hierarchical structure of such core-shell micro-granules has been rigorously characterized using small-angle neutron and X-ray scattering techniques and complemented with scanning electron microscopy. The hydrophilic silica envelope around the carbon core helps in incorporation of such granules into the hydrophilic polymeric ultra-filtration membrane. The interstitial micro-pores present in the silica shell can serve as water transport channels and the mesoporus carbon core enhances the separation performance due its well adsorption characteristics. It has been found that the incorporation of such granules inside the ultra-filtration membrane indeed enhances the water permeability as well as the separation performance in a significant way.

  8. Preparation of resveratrol-loaded nanoporous silica materials with different structures

    Science.gov (United States)

    Popova, Margarita; Szegedi, Agnes; Mavrodinova, Vesselina; Novak Tušar, Natasa; Mihály, Judith; Klébert, Szilvia; Benbassat, Niko; Yoncheva, Krassimira

    2014-11-01

    Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound.

  9. Effect of structure on nonlinear optical properties in CaCu{sub 3}Ti{sub 4}O{sub 12} films

    Energy Technology Data Exchange (ETDEWEB)

    Ning, Tingyin [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Zhou, Yueliang, E-mail: ylzhou@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-12-21

    We report the third-order nonlinear optical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} films with different preferred growth orientations on MgO and fused silica substrates. The films have (310)- and (220)-orientation on MgO and fused silica, respectively, due to the lattice-mismatch. Raman spectra further indicate different atom-bonding states in the films. The nonlinear optical measurements show the films possess the same self-defocusing behavior but with different values of nonlinear refraction, and changed signs of nonlinear absorption. The difference of optical nonlinearity in CaCu{sub 3}Ti{sub 4}O{sub 12} films is ascribed to different lattice parameters and intermediate levels induced by structure.

  10. Structure and dynamics of spin-labeled insulin entrapped in a silica matrix by the sol-gel method.

    Science.gov (United States)

    Vanea, E; Gruian, C; Rickert, C; Steinhoff, H-J; Simon, V

    2013-08-12

    The structure and conformational dynamics of insulin entrapped into a silica matrix was monitored during the sol to maturated-gel transition by electron paramagnetic resonance (EPR) spectroscopy. Insulin was successfully spin-labeled with iodoacetamide and the bifunctional nitroxide reagent HO-1944. Room temperature continuous wave (cw) EPR spectra of insulin were recorded to assess the mobility of the attached spin labels. Insulin conformation and its distribution within the silica matrix were studied using double electron-electron resonance (DEER) and low-temperature cw-EPR. A porous oxide matrix seems to form around insulin molecules with pore diameters in the order of a few nanometers. Secondary structure of the encapsulated insulin investigated by Fourier transform infrared spectroscopy proved a high structural integrity of insulin even in the dried silica matrix. The results show that silica encapsulation can be used as a powerful tool to effectively isolate and functionally preserve biomolecules during preparation, storage, and release.

  11. Structure study of the tri-continuous mesoporous silica IBN-9 by electron crystallography

    KAUST Repository

    Zhang, Daliang

    2011-12-01

    High resolution electron microscopy (HRTEM) has unique advantages for structural determination of nano-sized porous materials compared to X-ray diffraction, because it provides the important structure factor phase information which is lost in diffraction. Here we demonstrate the structure determination of the first tri-continuous mesoporous silica IBN-9 by electron crystallography. IBN-9 has a hexagonal unit cell with the space group P6 3/mcm and a = 88.4 , c = 84.3 . HRTEM images taken along three main directions, [0 0 1], [11̄0] and [1 0 0] were combined to reconstruct the 3D electrostatic potential map, from which the tri-continuous pore structure of IBN-9 was discovered. The different steps of structure determination of unknown mesoporous structures by electron crystallography are described in details. Similar procedures can also be applied for structure determination of other porous and nonporous crystalline materials. © 2011 Elsevier Inc. All rights reserved.

  12. Nanostructured antistatic and antireflective thin films made of indium tin oxide and silica over-coat layer

    Science.gov (United States)

    Cho, Young-Sang; Hong, Jeong-Jin; Yang, Seung-Man; Choi, Chul-Jin

    2010-08-01

    Stable dispersion of colloidal indium tin oxide nanoparticles was prepared by using indium tin oxide nanopowder, organic solvent, and suitable dispersants through attrition process. Various comminution parameters during the attrition step were studied to optimize the process for the stable dispersion of indium tin oxide sol. The transparent and conductive films were fabricated on glass substrate using the indium tin oxide sol by spin coating process. To obtain antireflective function, partially hydrolyzed alkyl silicate was deposited as over-coat layer on the pre-fabricated indium tin oxide film by spin coating technique. This double-layered structure of the nanostructured film was characterized by measuring the surface resistance and reflectance spectrum in the visible wavelength region. The final film structure was enough to satisfy the TCO regulations for EMI shielding purposes.

  13. Ice films follow structure zone model morphologies

    International Nuclear Information System (INIS)

    Cartwright, Julyan H.E.; Escribano, Bruno; Sainz-Diaz, C. Ignacio

    2010-01-01

    Ice films deposited at temperatures of 6-220 K and at low pressures in situ in a cryo-environmental scanning electron microscope show pronounced morphologies at the mesoscale consistent with the structure zone model of film growth. Water vapour was injected directly inside the chamber at ambient pressures ranging from 10 -4 Pa to 10 2 Pa. Several different substrates were used to exclude the influence of their morphology on the grown films. At the lowest temperatures the ice, which under these conditions is amorphous on the molecular scale, shows the mesoscale morphologies typical of the low-temperature zones of the structure zone model (SZM), including cauliflower, transition, spongelike and matchstick morphologies. Our experiments confirm that the SZM is independent of the chemical nature of the adsorbate, although the intermolecular interactions in water (hydrogen bonds) are different to those in ceramics or metals. At higher temperatures, on the other hand, where the ice is hexagonal crystalline on the molecular scale, it displays a complex palmlike morphology on the mesoscale.

  14. Ice films follow structure zone model morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Cartwright, Julyan H.E. [Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, E-18071 Granada (Spain); Escribano, Bruno, E-mail: bruno.escribano.salazar@gmail.co [Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, E-18071 Granada (Spain); Sainz-Diaz, C. Ignacio [Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, E-18071 Granada (Spain)

    2010-04-02

    Ice films deposited at temperatures of 6-220 K and at low pressures in situ in a cryo-environmental scanning electron microscope show pronounced morphologies at the mesoscale consistent with the structure zone model of film growth. Water vapour was injected directly inside the chamber at ambient pressures ranging from 10{sup -4} Pa to 10{sup 2} Pa. Several different substrates were used to exclude the influence of their morphology on the grown films. At the lowest temperatures the ice, which under these conditions is amorphous on the molecular scale, shows the mesoscale morphologies typical of the low-temperature zones of the structure zone model (SZM), including cauliflower, transition, spongelike and matchstick morphologies. Our experiments confirm that the SZM is independent of the chemical nature of the adsorbate, although the intermolecular interactions in water (hydrogen bonds) are different to those in ceramics or metals. At higher temperatures, on the other hand, where the ice is hexagonal crystalline on the molecular scale, it displays a complex palmlike morphology on the mesoscale.

  15. Silica-gel structural characterization during the initial phases of gelation and drying; Caracterizacao estrutural de geis de silica durante as etapas iniciais de gelacao e secagem

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Max Passos

    1997-12-31

    For centuries, glasses and ceramics have been made via melting or solid state reactions at temperatures above 100 deg C. The sol-gel process offers new approaches to the synthesis of glasses and ceramics, combining control of composition and structure at the molecular level with the ability to shape materials in bulk, powder, fiber and thin-film forms. The growth of sol-gel technology research is due to the many unique features of that class of materials. Major applications include optical elements and integrated optical devices, ceramic filters, membranes, supercondutors, magnetic, catalytic and manostructured materials to antioxidant, anticorrosion coatings and composite and biomedical materials. In this work a variety of techniques like spectroscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, light scattering nuclear magnetic resonance, X ray diffraction and nitrogen adsorption have been employed to investigate the initial phase of the sol-gel transition of gamma ray irradiated tetramethoxysilane (TMOS) solutions and non-irradiated TMOS solution and to get information about the structure of the silica gels obtained under different gelation conditions. Typically the tetramethoxysilane solutions were prepared using a molar ratio of TMOS to demineralized water of 1 to 16. Some experiments were made under catalysed conditions. The mixing was carried out at room temperature. The turbidity and light scattering experiments on the polycondensation of tetramethoxysilane show that exists no drastic difference in the gelling time of a gamma ray irradiated and a non-irradiated TMOS+H{sub 2}O (1+16 M) solution. In the absence of a catalyst, the gelling time for both reactions occurs in about 3.30 h. When HNO{sub 3} (o.03 M) was used, the gelling time observed was 3 days. Raman and ultraviolet-visible spectroscopy show no drastic difference during the initial phase at the sol-gel transition under ambient temperature/pressure and under gamma radiation. The gels

  16. Silica-gel structural characterization during the initial phases of gelation and drying; Caracterizacao estrutural de geis de silica durante as etapas iniciais de gelacao e secagem

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Max Passos

    1996-12-31

    For centuries, glasses and ceramics have been made via melting or solid state reactions at temperatures above 100 deg C. The sol-gel process offers new approaches to the synthesis of glasses and ceramics, combining control of composition and structure at the molecular level with the ability to shape materials in bulk, powder, fiber and thin-film forms. The growth of sol-gel technology research is due to the many unique features of that class of materials. Major applications include optical elements and integrated optical devices, ceramic filters, membranes, supercondutors, magnetic, catalytic and manostructured materials to antioxidant, anticorrosion coatings and composite and biomedical materials. In this work a variety of techniques like spectroscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, light scattering nuclear magnetic resonance, X ray diffraction and nitrogen adsorption have been employed to investigate the initial phase of the sol-gel transition of gamma ray irradiated tetramethoxysilane (TMOS) solutions and non-irradiated TMOS solution and to get information about the structure of the silica gels obtained under different gelation conditions. Typically the tetramethoxysilane solutions were prepared using a molar ratio of TMOS to demineralized water of 1 to 16. Some experiments were made under catalysed conditions. The mixing was carried out at room temperature. The turbidity and light scattering experiments on the polycondensation of tetramethoxysilane show that exists no drastic difference in the gelling time of a gamma ray irradiated and a non-irradiated TMOS+H{sub 2}O (1+16 M) solution. In the absence of a catalyst, the gelling time for both reactions occurs in about 3.30 h. When HNO{sub 3} (o.03 M) was used, the gelling time observed was 3 days. Raman and ultraviolet-visible spectroscopy show no drastic difference during the initial phase at the sol-gel transition under ambient temperature/pressure and under gamma radiation. The gels

  17. Preparation of resveratrol-loaded nanoporous silica materials with different structures

    Energy Technology Data Exchange (ETDEWEB)

    Popova, Margarita, E-mail: mpopova@orgchem.bas.bg [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Szegedi, Agnes [Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, 1117 Budapest, Magyar tudósok körútja 2. (Hungary); Mavrodinova, Vesselina [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Novak Tušar, Natasa [National Institute of Chemistry, Ljubljana (Slovenia); Mihály, Judith; Klébert, Szilvia [Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, 1117 Budapest, Magyar tudósok körútja 2. (Hungary); Benbassat, Niko; Yoncheva, Krassimira [Faculty of Pharmacy, 2 Dunav Str., 1000 Sofia (Bulgaria)

    2014-11-15

    Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound. - Graphical abstract: trans-Resveratrol was stabilized in the pores of BEA zeolite, MCM-41and KIL2 mesoporous silicas. - Highlights: • BEA, KIL-2 and MCM-41 materials were used as carriers for resveratrol loading. • Resveratrol encapsulation in ethanol solution and solid state procedure were applied. • The solid-state preparation appears very effective for stabilization of trans-resveratrol.

  18. Preparation of resveratrol-loaded nanoporous silica materials with different structures

    International Nuclear Information System (INIS)

    Popova, Margarita; Szegedi, Agnes; Mavrodinova, Vesselina; Novak Tušar, Natasa; Mihály, Judith; Klébert, Szilvia; Benbassat, Niko; Yoncheva, Krassimira

    2014-01-01

    Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound. - Graphical abstract: trans-Resveratrol was stabilized in the pores of BEA zeolite, MCM-41and KIL2 mesoporous silicas. - Highlights: • BEA, KIL-2 and MCM-41 materials were used as carriers for resveratrol loading. • Resveratrol encapsulation in ethanol solution and solid state procedure were applied. • The solid-state preparation appears very effective for stabilization of trans-resveratrol

  19. Structure and spectral properties of the silver-containing high-silica glasses

    International Nuclear Information System (INIS)

    Girsova, M A; Golovina, G F; Anfimova, I N; Antropova, T V; Arsent'ev, M Yu

    2016-01-01

    Silver-containing high-silica glasses were synthesized by an impregnation of the silica porous glasses (PGs) first with AgNO 3 aqueous solution (with or without the presence of the sensitizers, such as Cu(NO 3 ) 2 or Ce(NO 3 ) 3 ), next in the mixed halide salt (NH 4 Cl, KBr, KI) solution. Then some part of the samples was sintered at the temperatures from 850 to 900°C up to closing of the pores. The structure of glasses was studied by UV-VIS-NIR and IR spectroscopy and X-ray diffraction (XRD) techniques. According to XRD data the silver-containing high-silica glasses contain the AgBr, AgI, Ag 3 PO 4 , (CuBr) 0.75 (CuI) 0.25 phases. IR spectra confirmed B-O-B, Si- O-Si, P-O-P, O-P-O, O-B-O bonds, (PO 4 ) 3- and P-O - groups in glasses. (paper)

  20. Solvothermal growth of a ruthenium metal-organic framework featuring HKUST-1 structure type as thin films on oxide surfaces.

    Science.gov (United States)

    Kozachuk, Olesia; Yusenko, Kirill; Noei, Heshmat; Wang, Yuemin; Walleck, Stephan; Glaser, Thorsten; Fischer, Roland A

    2011-08-14

    Phase-pure crystalline thin films of a mixed-valence Ru(2)(II,III) metal-organic framework with 1,3,5-benzenetricarboxylate (btc) as a linker were solvothermally grown on amorphous alumina and silica surfaces. Based on the Rietveld refinement, the structure of Ru-MOF was assigned to be analogous to [Cu(3)(btc)(2)] (HKUST-1). This journal is © The Royal Society of Chemistry 2011

  1. Organic-Inorganic Hydrophobic Nanocomposite Film with a Core-Shell Structure

    Directory of Open Access Journals (Sweden)

    Peng Liu

    2016-12-01

    Full Text Available A method to prepare novel organic-inorganic hydrophobic nanocomposite films was proposed by a site-specific polymerization process. The inorganic part, the core of the nanocomposite, is a ternary SiO2–Al2O3–TiO2 nanoparticles, which is grafted with methacryloxy propyl trimethoxyl silane (KH570, and wrapped by fluoride and siloxane polymers. The synthesized samples are characterized by transmission electron microscopy (TEM, Fourier transform infrared (FTIR spectrscopy, X-ray diffractometry (XRD, contact angle meter (CA, and scanning electron microscope (SEM. The results indicate that the novel organic-inorganic hydrophobic nanocomposite with a core-shell structure was synthesized successfully. XRD analysis reveals the nanocomposite film has an amorphous structure, and FTIR analysis indicates the nanoparticles react with a silane coupling agent (methacryloxy propyl trimethoxyl silane KH570. Interestingly, the morphology of the nanoparticle film is influenced by the composition of the core. Further, comparing with the film synthesized by silica nanoparticles, the film formed from SiO2–Al2O3–TiO2 nanoparticles has higher hydrophobic performance, i.e., the contact angle is greater than 101.7°. In addition, the TEM analysis reveals that the crystal structure of the particles can be changed at high temperatures.

  2. Thin film structures and phase stability

    International Nuclear Information System (INIS)

    Clemens, B.M.; Johnson, W.L.

    1990-01-01

    This was a two day symposium, with invited and contributed papers as well as an evening poster session. The first day concentrated on solid state reactions with invited talks by Lindsay Greer from the University of Cambridge, King Tu from IBM Yorktown Heights, and Carl Thompson from MIT. Professor Greer observed that the diffusion of Zr is 10 6 times slower than that of Ni in amorphous NiZr, confirming that Ni is the mobile species in solid state amorphization. King Tu explained the formation of metastable phases in this film diffusion couples by the concept of maximum rate of free energy change. Carl Thompson discussed the formation of amorphous phases in metal silicon systems, and discussed a two stage nucleation and growth process. The contributed papers also generated discussion on topics such as phase segregation, amorphous silicide formation, room temperature oxidation of silicon, and nucleation during ion beam irradiation. There was a lively poster session on Monday evening with papers on a wide variety of topics covering the general area of thin film science. The second day had sessions Epitaxy and Multilayer Structure I and II, with the morning focussing on epitaxial and heteroepitaxial growth of thin films. Robin Farrow of IBM Almaden led off with an invited talk where he reported on some remarkable success he and his co-workers have had in growing single crystal epitaxial thin films and superlattices of silver, iron, cobalt and platinum on GaAs. This was followed by several talks on epitaxial growth and characterization. The afternoon focused on interfaces and structure of multilayered materials. A session on possible stress origins of the supermodulus effect was highlighted by lively interaction from the audience. Most of the papers presented at the symposium are presented in this book

  3. Optical Degradation of Colloidal Eu-Complex Embedded in Silica Glass Film Using Reprecipitation and Sol-Gel Methods.

    Science.gov (United States)

    Fukuda, Takeshi; Kurabayashi, Tomokazu; Yamaki, Tatsuki

    2016-04-01

    A reprecipitation method has been investigated for fabricating colloidal nanoparticles using Eu-complex. Herein, we investigated optical degradation characteristics of (1,10-phenanthroline)tris [4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionato]europium(III) colloidal nanoparticles, which were embedded into a silica glass film fabricated by a conventional sol-gel process. At first, we tried several types of good solvents for the reprecipitation method, and dimethyl sulfoxide (DMSO) is found to be a suitable solvent for realizing the small diameter and the high long-term stability against the ultraviolet irradiation even though the boing point of DMSO is higher than that of water used as a poor solvent. By optimizing the good solvent and the concentration of Eu-complex, the relative photoluminescence intensity of 0.96 was achieved even though the ultraviolet light was continuously irradiated for 90 min. In addition, the average diameter of 106 nm was achieved when DMSO was used as a good solvent, resulting in the high transmittance at a visible wavelength region. Therefore, we can achieve the transparent emissive thin film with a center wavelength of 612 nm, and the optical degradation was drastically reduced by forming nanoparticles.

  4. STRUCTURING OF DIAMOND FILMS USING MICROSPHERE LITHOGRAPHY

    Directory of Open Access Journals (Sweden)

    Mária Domonkos

    2014-10-01

    Full Text Available In this study, the structuring of micro- and nanocrystalline diamond thin films is demonstrated. The structuring of the diamond films is performed using the technique of microsphere lithography followed by reactive ion etching. Specifically, this paper presents a four-step fabrication process: diamond deposition (microwave plasma assisted chemical vapor deposition, mask preparation (by the standard Langmuir-Blodgett method, mask modification and diamond etching. A self-assembled monolayer of monodisperse polystyrene (PS microspheres with close-packed ordering is used as the primary template. Then the PS microspheres and the diamond films are processed in capacitively coupled radiofrequency plasma  using different plasma chemistries. This fabrication method illustrates the preparation of large arrays of periodic and homogeneous hillock-like structures. The surface morphology of processed diamond films is characterized by scanning electron microscopy and atomic force microscope. The potential applications of such diamond structures in various fields of nanotechnology are also briefly discussed.

  5. The structural coloration of textile materials using self-assembled silica nanoparticles.

    Science.gov (United States)

    Gao, Weihong; Rigout, Muriel; Owens, Huw

    2017-01-01

    The work presented investigates how to produce structural colours on textile materials by applying a surface coating of silica nanoparticles (SNPs). Uniform SNPs with particle diameters in a controlled micron size range (207-350 nm) were synthesized using a Stöber-based solvent varying (SV) method which has been reported previously. Photonic crystals (PCs) were formed on the surface of a piece of textile fabric through a process of natural sedimentation self-assembly of the colloidal suspension containing uniform SNPs. Due to the uniformity and a particular diameter range of the prepared SNPs, structural colours were observed from the fabric surface due to the Bragg diffraction of white light with the ordered structure of the silica PCs. By varying the mean particle diameter, a wide range of spectral colours from red to blue were obtained. The comparison of structural colours on fabrics and on glasses suggests that a smooth substrate is critical when producing materials with high colour intensity and spatial uniformity. This work suggested a promising approach to colour textile materials without the need for traditional dyes and/or pigments. Graphical abstract.

  6. Detecting alkali-silica reaction in thick concrete structures using linear array ultrasound

    Science.gov (United States)

    Bull Ezell, N. Dianne; Albright, Austin; Clayton, Dwight; Santos-Villalobos, Hector

    2018-03-01

    Commercial nuclear power plants (NPPs) depend heavily on concrete structures, making the long-term performance of these structures crucial for safe operation, especially with license period extensions to 60 years and possibly beyond. Alkali-silica reaction (ASR) is a reaction that occurs over time in concrete between alkaline cement paste and reactive, noncrystalline silica (aggregates). In the presence of water, an expansive gel is formed within the aggregates, which results in microcracks in aggregates and adjacent cement paste. ASR can potentially affect concrete properties and performance characteristics such as compressive strength, modulus of elasticity, flexural stiffness, shear strength, and tensile strength. Currently, no nondestructive evaluation methods have proven effective in identifying ASR before surface cracks form. ASR is identified visibly or by petrographic analysis. Although ASR definitely impacts concrete material properties, the performance of concrete structures exhibiting ASR depends on whether or not the concrete is unconfined or confined with reinforcing bars. Confinement by reinforcing bars restrainsthe expansion of ASR-affected concrete, similar to prestressing, thus improving the performance of a structure. Additionally, there is no direct correlation between the mechanical properties of concrete sample cores and the in-situ properties of the concrete. The University of Tennessee-Knoxville, Oak Ridge National Laboratory, and a consortium of universities have developed an accelerated ASR experiment. Three large concrete specimens, representative of NPP infrastructure, were constructed containing both embedded and surface instruments. This paper presents preliminary analysis of these specimens using a frequency-banded synthetic aperture focusing technique.

  7. Ce+3-and Tb+3-luminescence in glasses. Ce+3-activated bulk silica and silica thin films. An α-particle detector based on a Ce+3-activated silica thin film. A Ce+3-Tb+3-energy transfer in a high melting point phosphate glass

    International Nuclear Information System (INIS)

    Heindl, R.; Loriers, J.; Sella, J.C.; Robert, A.

    1984-07-01

    While many Ce +3 -activated glasses of different type emit strongly under UV (253,7 nm) and β-ray excitation, only the commercial silicate glass NE 905 shows an useful emission when exposed to α-particles. Only phosphate glasses have give the green Tb +3 -emission, when doped by it, under UV and α and β radiation. Sputtered films of Ce +3 -activated silica have appropriate luminescence properties, adherence to the substrate and a perfect chemical resistance to hot nitric acid. An α-particle detector has been built which has permitted the quantitative detection of plutonium in the presence of other radiative ions

  8. Fluctuations and structure of amphiphilic films; Fluctuations et structure de films d`amphiphiles

    Energy Technology Data Exchange (ETDEWEB)

    Gourier, CH

    1996-07-01

    This thesis is divided in three parts.The first part exposes in a theoretical point of view, how the fluctuations spectrum of an amphiphilic film is governed by its properties and its bidimensional characteristics.The measurements of fluctuations spectra of an interface are accessible with the measurement of intensity that interface diffuses out of the specular angle, we present in the second chapter the principles of the X rays diffusion by a real interface and see how the diffuse diffusion experiments allow to determine the fluctuations spectrum of an amphiphilic film. The second part is devoted to the different experimental techniques that have allowed to realize the study of fluctuation as well as the structural study.The third part is devoted to experimental results concerning the measurements of fluctuations spectra and to the study of the structure of amphiphilic films. We show that it is possible by using an intense source of X rays (ESRF: European Synchrotron Radiation Facility) to measure the water and amphiphilic films fluctuations spectra until molecular scales. The last chapter is devoted to the structural study and film fluctuations made of di-acetylenic molecules. (N.C.)

  9. Control of silicification by genetically engineered fusion proteins: Silk–silica binding peptides

    Science.gov (United States)

    Zhou, Shun; Huang, Wenwen; Belton, David J.; Simmons, Leo O.; Perry, Carole C.; Wang, Xiaoqin; Kaplan, David L.

    2014-01-01

    In the present study, an artificial spider silk gene, 6mer, derived from the consensus sequence of Nephila clavipes dragline silk gene, was fused with different silica-binding peptides (SiBPs), A1, A3 and R5, to study the impact of the fusion protein sequence chemistry on silica formation and the ability to generate a silk–silica composite in two different bioinspired silicification systems: solution–solution and solution– solid. Condensed silica nanoscale particles (600–800 nm) were formed in the presence of the recombinant silk and chimeras, which were smaller than those formed by 15mer-SiBP chimeras [1], revealing that the molecular weight of the silk domain correlated to the sizes of the condensed silica particles in the solution system. In addition, the chimeras (6mer-A1/A3/R5) produced smaller condensed silica particles than the control (6mer), revealing that the silica particle size formed in the solution system is controlled by the size of protein assemblies in solution. In the solution–solid interface system, silicification reactions were performed on the surface of films fabricated from the recombinant silk proteins and chimeras and then treated to induce β-sheet formation. A higher density of condensed silica formed on the films containing the lowest β-sheet content while the films with the highest β-sheet content precipitated the lowest density of silica, revealing an inverse correlation between the β-sheet secondary structure and the silica content formed on the films. Intriguingly, the 6mer-A3 showed the highest rate of silica condensation but the lowest density of silica deposition on the films, compared with 6mer-A1 and -R5, revealing antagonistic crosstalk between the silk and the SiBP domains in terms of protein assembly. These findings offer a path forward in the tailoring of biopolymer–silica composites for biomaterial related needs. PMID:25462851

  10. Structural determinants for protein adsorption/non-adsorption to silica surface

    International Nuclear Information System (INIS)

    Mathe, Christelle; Devineau, Stephanie; Aude, Jean-Christophe; Lagniel, Gilles; Chedin, Stephane; Legros, Veronique; Mathon, Marie-Helene; Renault, Jean-Philippe; Pin, Serge; Boulard, Yves; Labarre, Jean

    2013-01-01

    The understanding of the mechanisms involved in the interaction of proteins with inorganic surfaces is of major interest in both fundamental research and applications such as nano-technology. However, despite intense research, the mechanisms and the structural determinants of protein/surface interactions are still unclear. We developed a strategy consisting in identifying, in a mixture of hundreds of soluble proteins, those proteins that are adsorbed on the surface and those that are not. If the two protein subsets are large enough, their statistical comparative analysis must reveal the physicochemical determinants relevant for adsorption versus non-adsorption. This methodology was tested with silica nanoparticles. We found that the adsorbed proteins contain a higher number of charged amino acids, particularly arginine, which is consistent with involvement of this basic amino acid in electrostatic interactions with silica. The analysis also identified a marked bias toward low aromatic amino acid content (phenylalanine, tryptophan, tyrosine and histidine) in adsorbed proteins. Structural analyses and molecular dynamics simulations of proteins from the two groups indicate that non-adsorbed proteins have twice as many p-p interactions and higher structural rigidity. The data are consistent with the notion that adsorption is correlated with the flexibility of the protein and with its ability to spread on the surface. Our findings led us to propose a refined model of protein adsorption. (authors)

  11. Structural determinants for protein adsorption/non-adsorption to silica surface.

    Directory of Open Access Journals (Sweden)

    Christelle Mathé

    Full Text Available The understanding of the mechanisms involved in the interaction of proteins with inorganic surfaces is of major interest in both fundamental research and applications such as nanotechnology. However, despite intense research, the mechanisms and the structural determinants of protein/surface interactions are still unclear. We developed a strategy consisting in identifying, in a mixture of hundreds of soluble proteins, those proteins that are adsorbed on the surface and those that are not. If the two protein subsets are large enough, their statistical comparative analysis must reveal the physicochemical determinants relevant for adsorption versus non-adsorption. This methodology was tested with silica nanoparticles. We found that the adsorbed proteins contain a higher number of charged amino acids, particularly arginine, which is consistent with involvement of this basic amino acid in electrostatic interactions with silica. The analysis also identified a marked bias toward low aromatic amino acid content (phenylalanine, tryptophan, tyrosine and histidine in adsorbed proteins. Structural analyses and molecular dynamics simulations of proteins from the two groups indicate that non-adsorbed proteins have twice as many π-π interactions and higher structural rigidity. The data are consistent with the notion that adsorption is correlated with the flexibility of the protein and with its ability to spread on the surface. Our findings led us to propose a refined model of protein adsorption.

  12. A facile and efficient method of enzyme immobilization on silica particles via Michael acceptor film coatings: immobilized catalase in a plug flow reactor.

    Science.gov (United States)

    Bayramoglu, Gulay; Arica, M Yakup; Genc, Aysenur; Ozalp, V Cengiz; Ince, Ahmet; Bicak, Niyazi

    2016-06-01

    A novel method was developed for facile immobilization of enzymes on silica surfaces. Herein, we describe a single-step strategy for generating of reactive double bonds capable of Michael addition on the surfaces of silica particles. This method was based on reactive thin film generation on the surfaces by heating of impregnated self-curable polymer, alpha-morpholine substituted poly(vinyl methyl ketone) p(VMK). The generated double bonds were demonstrated to be an efficient way for rapid incorporation of enzymes via Michael addition. Catalase was used as model enzyme in order to test the effect of immobilization methodology by the reactive film surface through Michael addition reaction. Finally, a plug flow type immobilized enzyme reactor was employed to estimate decomposition rate of hydrogen peroxide. The highly stable enzyme reactor could operate continuously for 120 h at 30 °C with only a loss of about 36 % of its initial activity.

  13. Modeling of the structure and properties of oxygen vacancies in amorphous silica

    International Nuclear Information System (INIS)

    Mukhopadhyay, Sanghamitra; Sushko, Peter V.; Stoneham, A. Marshall; Shluger, Alexander L.

    2004-01-01

    We used an embedded cluster method to predict and characterize possible structural types of neutral and positively charged oxygen vacancies in amorphous silica. Defects were treated at 70 different oxygen sites of continuous random network amorphous structure generated using classical molecular dynamics. The neutral vacancies are characterized by a wide distribution of formation energies and structural parameters. Our modeling predicts the two major structural types of positively charged vacancies (E ' centers): dimer and dangling bond centers. The local structure of both types of centers depends on the medium range structure of the surrounding amorphous network. The majority of the dangling bond centers are unpuckered. We used structural 'fingerprints' derived from similar calculations of oxygen vacancy type centers in quartz and from experiment to find two other structural types of dangling bond centers: the puckered configuration and the back-projected configuration of E ' centers. In each case we find a distribution of both structural and EPR parameters. However, the average values of the EPR parameters for all dangling bond configurations are very similar. The structural criteria which favor the formation of different types of centers in the original amorphous structure are formulated in terms of the average Si-O distance of oxygen ion with its two neighboring silicon ions

  14. Mechanics of evolving thin film structures

    Science.gov (United States)

    Liang, Jim

    In the Stranski-Krastanov system, the lattice mismatch between the film and the substrate causes the film to break into islands. During annealing, both the surface energy and the elastic energy drive the islands to coarsen. Motivated by several related studies, we suggest that stable islands should form when a stiff ceiling is placed at a small gap above the film. We show that the role of elasticity is reversed: with the ceiling, the total elastic energy stored in the system increases as the islands coarsen laterally. Consequently, the islands select an equilibrium size to minimize the combined elastic energy and surface energy. In lithographically-induced self-assembly, when a two-phase fluid confined between parallel substrates is subjected to an electric field, one phase can self-assemble into a triangular lattice of islands in another phase. We describe a theory of the stability of the island lattice. The islands select the equilibrium diameter to minimize the combined interface energy and electrostatic energy. Furthermore, we study compressed SiGe thin film islands fabricated on a glass layer, which itself lies on a silicon wafer. Upon annealing, the glass flows, and the islands relax. A small island relaxes by in-plane expansion. A large island, however, wrinkles at the center before the in-plane relaxation arrives. The wrinkles may cause significant tensile stress in the island, leading to fracture. We model the island by the von Karman plate theory and the glass layer by the Reynolds lubrication theory. Numerical simulations evolve the in-plane expansion and the wrinkles simultaneously. We determine the critical island size, below which in-plane expansion prevails over wrinkling. Finally, in devices that integrate dissimilar materials in small dimensions, crack extension in one material often accompanies inelastic deformation in another. We analyze a channel crack advancing in an elastic film under tension, while an underlayer creeps. We use a two

  15. Optical constants and structural properties of thin gold films

    DEFF Research Database (Denmark)

    Yakubovsky, Dmitry I.; Arsenin, Aleksey V.; Stebunov, Yury V.

    2017-01-01

    We report a comprehensive experimental study of optical and electrical properties of thin polycrystalline gold films in a wide range of film thicknesses (from 20 to 200 nm). Our experimental results are supported by theoretical calculations based on the measured morphology of the fabricated gold...... rules for thin-film plasmonic and nanophotonic devices....... films. We demonstrate that the dielectric function of the metal is determined by its structural morphology. Although the fabrication process can be absolutely the same for different films, the dielectric function can strongly depend on the film thickness. Our studies show that the imaginary part...

  16. Physical phenomena stipulating nucleus formation, growth and structure films

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrov, L N [AN SSSR, Novosibirsk. Inst. Fiziki Poluprovodnikov

    1975-03-01

    This review is concerned with the physical phenomena responsible for the nucleation, growth and structure of films. Emphasis is placed on the study of films of solid-metal systems, semiconductors (In, As, Cd, Se, CdS), and dielectrics. The following problems are discussed in the paper: general regularities of the thermodynamics and kinetics of film formation, methods of obtaining a solid film, the process of film formation, the rate of growth of individual grains. The critical film thickness and its measurement are also considered. The results of investigating the process of formation of mono- and polycrystalline films are discussed. It is concluded, on the basis of studies into the relaxation processes accompanying the growth of films, that an insight into these processes will permits improving film properties.

  17. Significance of Alkali-Silica reaction in nuclear safety-related concrete structures

    International Nuclear Information System (INIS)

    Le Pape, Y.; Field, K.G.; Mattus, C.H.; Naus, D.J.; Busby, J.T.; Saouma, V.; Ma, Z.J.; Cabage, J.V.; Guimaraes, M.

    2015-01-01

    Nuclear Power Plant license renewal up to 60 years and possible life extension beyond has established a renewed focus on long-term aging of nuclear generating stations materials, and particularly, on concrete. Large irreplaceable sections of most nuclear generating stations include concrete components. The Expanded Materials Degradation Analysis, jointly performed by the Department of Energy, the U.S. Nuclear Regulatory Commission, the Academia and the Power Generation Industry, identified the need to develop a consistent knowledge base of alkali-silica reaction (ASR) within concrete as an urgent priority (Graves et al., 2014). ASR results in an expansion of Concrete produced by the reaction between alkali (generally from cement), reactive aggregate (like amorphous silica) and water absorption. ASR causes expansion, cracking and loss of mechanical properties. Considering that US commercial reactors in operation enter the age when ASR distress can be potentially observed and that numerous non-nuclear infrastructures (transportation, energy production) in a majority of the States have already experienced ASR-related concrete degradation, the susceptibility and significance of ASR for nuclear concrete structures must be addressed. This paper outlines an on-going research program including the investigation of the possibility of ASR in nuclear power plants, and the assessment of the residual shear bearing capacity of ASR-subjected nuclear structures. (authors)

  18. Synthesis and characterization of nano structures of Silica SBA-16 containing Gadolinium-159 as potential nanoparticulated system for cancer therapy

    International Nuclear Information System (INIS)

    Oliveira, Andre Felipe de

    2013-01-01

    Cancer is a leading cause of death worldwide, and malignant neoplasms of the lung, stomach, liver, colon and breast in greater numbers. And recently observed in the literature a large number of reviews where new materials, especially nanoparticle, has been studied as drug carriers and radioisotopes applied to cancer treatment. How mesoporous materials based on silica, thanks to its huge surface area and biocompatibility, have been studied intensively providing broad applications in various areas, the use of nanostructured silica SBA-16 might be a carrier specific radioisotope accumulate in the cells malignant. Thus the aim of this study is to develop in vitro studies using SBA-16 can selectively concentrate in malignant cells therapeutic amounts of the radioisotope Gadolinium-159 escorting them to death. This work was performed orderly synthesis of mesoporous silica, SBA-16 and incorporating the complex Gd-DTPA-BMA, as well as chemical and structural characterization. The techniques used to analyze the occurrence of the incorporation of the gadolinium complex in the silica matrix were elemental analysis (CHN), atomic emission spectroscopy (ICP-AES), infrared spectroscopy (FTIR), nitrogen adsorption (BET), small-angle X-ray scattering (SAXS) and thermogravimetric analysis (TG). To analyze the morphology of pure silica used the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By photon correlation spectroscopy (PCS) it was possible to obtain a measure of mean particle size, the polydispersity index (PDI) of the silica SBA-16, and the zeta potential by laser Doppler anemometry (LDA). The results of incorporation analyzed by ICP-AES indicated that the material SBA-16 had a higher rate of incorporation of gadolinium (93%). The release kinetics in simulated body fluid, showed considerable stability and low release (1%). The mesoporous silica SBA-16 showed cell viability in direct contact with cell culture. Samples with gadolinium

  19. Metal Oxide Thin Films Grafted on Silica Gel Surfaces: Recent Advances on the Analytical Application of these Materials

    Directory of Open Access Journals (Sweden)

    Gushikem Yoshitaka

    2001-01-01

    Full Text Available In the highly dispersed MxOy monolayer film on a porous SiO2 surface, denoted as SiO2/MxOy, the Si-O-M covalent bond formed on the SiO2 surface restricts the mobility of the attached oxide resulting in coordinatively unsaturated metal oxides (LAS in addition to the Brønsted acid sites (BAS. The BAS arise from the MOH and SiOH groups, the latter due to the unreacted silanol groups. As the attached oxides are strongly immobilized on the surface, they are also thermally very stable. The amphoteric character of most of the attached oxides allows the immobilization of various chemical species, acid or bases, resulting in a wide application of these surface modified materials. In this work many of the recent applications of these MxOy coated silica surfaces are described, such as selective adsorbents, in preconcentration processes, as new packing material for use in HPLC, support for immobilization of enzymes, amperometric electrodes, sensors and biosensors

  20. Bidisperse silica nanoparticles close-packed monolayer on silicon substrate by three step spin method

    Science.gov (United States)

    Khanna, Sakshum; Marathey, Priyanka; Utsav, Chaliawala, Harsh; Mukhopadhyay, Indrajit

    2018-05-01

    We present the studies on the structural properties of monolayer Bidisperse silica (SiO2) nanoparticles (BDS) on Silicon (Si-100) substrate using spin coating technique. The Bidisperse silica nanoparticle was synthesised by the modified sol-gel process. Nanoparticles on the substrate are generally assembled in non-close/close-packed monolayer (CPM) form. The CPM form is obtained by depositing the colloidal suspension onto the silicon substrate using complex techniques. Here we report an effective method for forming a monolayer of bidisperse silica nanoparticle by three step spin coating technique. The samples were prepared by mixing the monodisperse solutions of different particles size 40 and 100 nm diameters. The bidisperse silica nanoparticles were self-assembled on the silicon substrate forming a close-packed monolayer film. The scanning electron microscope images of bidisperse films provided in-depth film structure of the film. The maximum surface coverage obtained was around 70-80%.

  1. Influence of alkali-silica reaction on the physical, mechanical, and structural behaviour of reinforced concrete

    DEFF Research Database (Denmark)

    Barbosa, Ricardo Antonio

    Alkali-silica reaction (ASR) is one of the major concrete deterioration mechanisms in the world. Cracking in concrete structures due to ASR has been observed worldwide. In Denmark numerous concrete structures have been built with a critical amount of ASR-reactive aggregate, mostly as porous opaline...... and porous calcareous opaline flint in the fine aggregate fraction. During the last few decades, an increasing number of bridges in Denmark have been severely damaged due to ASR. In the most severe cases, the ASR-damaged bridges have been demolished and reconstructed due to uncertainty about their residual...... following features in common: (a) significant amount of ASR cracks were observed on and inside the slabs, (b) the ASR cracks were oriented parallel to the plane of the slabs, and (c) ASR occurred in the fine aggregate fraction. In this PhD study, both the compressive strength and tensile strength of drilled...

  2. Concentration of small ring structures in vitreous silica from a first-principles analysis of the Raman spectrum.

    Science.gov (United States)

    Umari, P; Gonze, Xavier; Pasquarello, Alfredo

    2003-01-17

    Using a first-principles approach, we calculate Raman spectra for a model structure of vitreous silica. We develop a perturbational method for calculating the dielectric tensor in an ultrasoft pseudopotential scheme and obtain Raman coupling tensors by finite differences with respect to atomic displacements. For frequencies below 1000 cm(-1), the parallel-polarized Raman spectrum of vitreous silica is dominated by oxygen bending motions, showing a strong sensitivity to the intermediate range structure. By modeling the Raman coupling, we derive estimates for the concentrations of three- and four-membered rings from the experimental intensities of the Raman defect lines.

  3. Reinforcement of Natural Rubber with Core-Shell Structure Silica-Poly(Methyl Methacrylate Nanoparticles

    Directory of Open Access Journals (Sweden)

    Qinghuang Wang

    2012-01-01

    Full Text Available A highly performing natural rubber/silica (NR/SiO2 nanocomposite with a SiO2 loading of 2 wt% was prepared by combining similar dissolve mutually theory with latex compounding techniques. Before polymerization, double bonds were introduced onto the surface of the SiO2 particles with the silane-coupling agent. The core-shell structure silica-poly(methyl methacrylate, SiO2-PMMA, nanoparticles were formed by grafting polymerization of MMA on the surface of the modified SiO2 particles via in situ emulsion, and then NR/SiO2 nanocomposite was prepared by blending SiO2-PMMA and PMMA-modified NR (NR-PMMA. The Fourier transform infrared spectroscopy results show that PMMA has been successfully introduced onto the surface of SiO2, which can be well dispersed in NR matrix and present good interfacial adhesion with NR phase. Compared with those of pure NR, the thermal resistance and tensile properties of NR/SiO2 nanocomposite are significantly improved.

  4. Growth, structure, and optical properties of carbon-reinforced silica fibers

    International Nuclear Information System (INIS)

    Zhang, Z. J.; Ajayan, P. M.; Ramanath, G.; Vacik, J.; Xu, Y. H.

    2001-01-01

    We report the synthesis of carbon-reinforced silica fibers by methane exposure of metallocene-treated oxidized-Si(001) substrates at 1100 degree C. The SiO 2 cap layer transforms into silica fibers reinforced by glassy carbon in the core during methane exposure. High-resolution electron microscopy and spatially resolved spectroscopy measurements of the fibers reveal an amorphous structure without a hollow, and domains of glassy carbon embedded at the fiber core. The carbon-reinforced fibers are optically transparent and have an optical band gap of ≅3.1 eV. These fibers are organized in radial patterns that vary for different metallocene species. On nickelocene-treated substrates, the fibers originate from the circumference of the circular templates and grow outwards, forming radial patterns. On ferrocene-treated substrates, randomly oriented fibers grow within as well as slightly outside the perimeter of the templates, forming wreath-like patterns. Aligned growth of such fibers could be useful for fabricating optoelectronics devices and reinforced composites. [copyright] 2001 American Institute of Physics

  5. Fabrication of transparent superhydrophobic silica-based film on a glass substrate

    Science.gov (United States)

    Wang, Shing-Dar; Luo, Shih-Shiang

    2012-05-01

    Tetraethoxysilane (TEOS) was hydrolyzed in an acidic environment and then reacted with hexamethyldisilazane (HMDS) to obtain a superhydrophobic transparent film on a glass substrate. The molar ratios of water and ethanol to TEOS, the pH value of the acidic (or basic) water that is used to hydrolyze TEOS, the heat treatment conditions and other factors were investigated systematically to optimize the transmission through, and the contact angle of water on the film. HMDS (total amount of HMDS/TEOS = 2) was divided into 20 parts, which were added into the sol successively to prevent the sudden production of a large quantity of NH3 in a small area of the sol. The optical and hydrophobic properties of the sol gel continued to change after it had been prepared. The conditions that TEOS was hydrolyzed with acidic water at pH 1.2 at 70 °C and the sol gel was aged at 20 °C for 48 h realized transmission of 90.9% and a water contact angle of 154.3°. No additional surface chemistry modification was needed.

  6. Pd-Ni-MWCNT nanocomposite thin films: preparation and structure

    Science.gov (United States)

    Kozłowski, Mirosław; Czerwosz, ElŻbieta; Sobczak, Kamil

    2017-08-01

    The properties of nanocomposite palladium-nickel-multi-walled (Pd-Ni-MWCNT) films deposited on aluminum oxide (Al2O3) substrate have been prepared and investigated. These films were obtained by 3 step process consisted of PVD/CVD/PVD methods. The morphology and structure of the obtained films were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques at various stages of the film formation. EDX spectrometer was used to measurements of elements segregation in the obtained film. TEM and STEM (Scanning Transmission Electron Microscopy) observations showed MWCNTs decorated with palladium nanoparticles in the film obtained in the last step of film formation (final PVD process). The average size of the palladium nanoparticles observed both on MWCNTs and carbonaceous matrix does not exceed 5 nm. The research was conducted on the use of the obtained films as potential sensors of gases (e.g. H2, NH3, CO2) and bio-sensors or optical sensors.

  7. Lanthanoid titanate film structure deposited at different temperatures in vacuum

    International Nuclear Information System (INIS)

    Kushkov, V.D.; Zaslavskij, A.M.; Mel'nikov, A.V.; Zverlin, A.V.; Slivinskaya, A.Eh.

    1991-01-01

    Influence of deposition temperature on the structure of lanthanoid titanate films, prepared by the method of high-rate vacuum condensation. It is shown that formation of crystal structure, close to equilibrium samples, proceeds at 1100-1300 deg C deposition temperatures. Increase of temperature in this range promotes formation of films with higher degree of structural perfection. Amorphous films of lanthanoid titanates form at 200-1000 deg C. Deposition temperature shouldn't exceed 1400 deg C to prevent the formation of perovskite like phases in films

  8. A Demonstration of Concrete Structural Health Monitoring Framework for Degradation due to Alkali-Silica Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Mahadevan, Sankaran [Idaho National Lab. (INL), Idaho Falls, ID (United States); Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States); Neal, Kyle [Idaho National Lab. (INL), Idaho Falls, ID (United States); Nath, Paromita [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bao, Yanqing [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cai, Guowei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Peter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Adams, Douglas [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kosson, David [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-04-01

    Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. This ongoing research project is seeking to develop a probabilistic framework for health diagnosis and prognosis of aging concrete structures in a nuclear power plant that is subjected to physical, chemical, environment, and mechanical degradation. The proposed framework consists of four elements: monitoring, data analytics, uncertainty quantification and prognosis. This report focuses on degradation caused by ASR (alkali-silica reaction). Controlled specimens were prepared to develop accelerated ASR degradation. Different monitoring techniques – thermography, digital image correlation (DIC), mechanical deformation measurements, nonlinear impact resonance acoustic spectroscopy (NIRAS), and vibro-acoustic modulation (VAM) -- were used to detect the damage caused by ASR. Heterogeneous data from the multiple techniques was used for damage diagnosis and prognosis, and quantification of the associated uncertainty using a Bayesian network approach. Additionally, MapReduce technique has been demonstrated with synthetic data. This technique can be used in future to handle large amounts of observation data obtained from the online monitoring of realistic structures.

  9. Synthesis of multilayered structure of nano-dimensional silica glass/reduced graphene oxide for advanced electrochemical applications.

    Science.gov (United States)

    Ghosh, Arnab; Miah, Milon; Majumder, Chinmoy; Bag, Shekhar; Chakravorty, Dipankar; Saha, Shyamal Kumar

    2018-03-28

    During the past few years, intensive research has been carried out to design new functional materials for superior electrochemical applications. Due to low storage capacity and low charge transport, silica based glasses have not yet been investigated for their supercapacitive behavior. Therefore, in the present study, a multilayered structure of silica-based nanoglass and reduced graphene oxide has been designed to remarkably enhance the specific capacitance by exploiting the porosity, large surface area, sufficient dangling bonds in the nanoglass and high electrical conductivity of rGO. The charge transport in the composite structure is also investigated to understand the electrochemical properties. It is found that Simmons tunneling or direct tunneling is the dominant mechanism of charge conduction between the graphene layers via the potential barrier of silica nanoglass phase. We believe that this study will open up a new area in the design of glass-based two-dimensional nanocomposites for superior supercapacitor applications.

  10. Synthesis, structural characterization and in vitro testing of dysprosium containing silica particles as potential MRI contrast enhancing agents

    Energy Technology Data Exchange (ETDEWEB)

    Chiriac, L.B.; Trandafir, D.L. [Faculty of Physics & National Magnetic Resonance Center, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania); Interdisciplinary Research Institute on Bio-Nano-Sciences & Faculty of Physics, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania); Turcu, R.V.F. [Faculty of Physics & National Magnetic Resonance Center, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania); Todea, M. [Interdisciplinary Research Institute on Bio-Nano-Sciences & Faculty of Physics, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania); Simon, S., E-mail: simons@phys.ubbcluj.ro [Faculty of Physics & National Magnetic Resonance Center, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania); Interdisciplinary Research Institute on Bio-Nano-Sciences & Faculty of Physics, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania)

    2016-11-01

    Highlights: • Dysprosium containing silica microparticles obtained by freeze and spray drying. • Higher structural units interconnection achieved in freeze vs. spray dried samples. • Dy occurance on the outermost layer of the microparticles evidenced by XPS. • Enhanced MRI contrast observed for freeze dried samples with 5% mol Dy{sub 2}O{sub 3}. - Abstract: The work is focused on synthesis and structural characterization of novel dysprosium-doped silica particles which could be considered as MRI contrast agents. Sol-gel derived silica rich particles obtained via freeze-drying and spray-drying processing methods were structurally characterized by XRD, {sup 29}Si MAS-NMR and XPS methods. The occurrence of dysprosium on the outermost layer of dysprosium containing silica particles was investigated by XPS analysis. The MRI contrast agent characteristics have been tested using RARE-T{sub 1} and RARE-T{sub 2} protocols. The contrast of MRI images delivered by the investigated samples was correlated with their local structure. Dysprosium disposal on microparticles with surface structure characterised by decreased connectivity of the silicate network units favours dark T{sub 2}-weighted MRI contrast properties.

  11. Synthesis, structural characterization and in vitro testing of dysprosium containing silica particles as potential MRI contrast enhancing agents

    International Nuclear Information System (INIS)

    Chiriac, L.B.; Trandafir, D.L.; Turcu, R.V.F.; Todea, M.; Simon, S.

    2016-01-01

    Highlights: • Dysprosium containing silica microparticles obtained by freeze and spray drying. • Higher structural units interconnection achieved in freeze vs. spray dried samples. • Dy occurance on the outermost layer of the microparticles evidenced by XPS. • Enhanced MRI contrast observed for freeze dried samples with 5% mol Dy_2O_3. - Abstract: The work is focused on synthesis and structural characterization of novel dysprosium-doped silica particles which could be considered as MRI contrast agents. Sol-gel derived silica rich particles obtained via freeze-drying and spray-drying processing methods were structurally characterized by XRD, "2"9Si MAS-NMR and XPS methods. The occurrence of dysprosium on the outermost layer of dysprosium containing silica particles was investigated by XPS analysis. The MRI contrast agent characteristics have been tested using RARE-T_1 and RARE-T_2 protocols. The contrast of MRI images delivered by the investigated samples was correlated with their local structure. Dysprosium disposal on microparticles with surface structure characterised by decreased connectivity of the silicate network units favours dark T_2-weighted MRI contrast properties.

  12. Grazing angle X-ray fluorescence from periodic structures on silicon and silica surfaces

    International Nuclear Information System (INIS)

    Nowak, S.H.; Banaś, D.; Błchucki, W.; Cao, W.; Dousse, J.-Cl.; Hönicke, P.; Hoszowska, J.; Jabłoński, Ł.; Kayser, Y.; Kubala-Kukuś, A.; Pajek, M.; Reinhardt, F.; Savu, A.V.; Szlachetko, J.

    2014-01-01

    Various 3-dimensional nano-scaled periodic structures with different configurations and periods deposited on the surface of silicon and silica substrates were investigated by means of the grazing incidence and grazing emission X-ray fluorescence techniques. Apart from the characteristics which are typical for particle- and layer-like samples, the measured angular intensity profiles show additional periodicity-related features. The latter could be explained by a novel theoretical approach based on simple geometrical optics (GO) considerations. The new GO-based calculations were found to yield results in good agreement with experiment, also in cases where other theoretical approaches are not valid, e.g., periodic particle distributions with an increased surface coverage

  13. Selective porous gates made from colloidal silica nanoparticles

    Directory of Open Access Journals (Sweden)

    Roberto Nisticò

    2015-11-01

    Full Text Available Highly selective porous films were prepared by spin-coating deposition of colloidal silica nanoparticles on an appropriate macroporous substrate. Silica nanoparticles very homogenous in size were obtained by sol–gel reaction of a metal oxide silica precursor, tetraethyl orthosilicate (TEOS, and using polystyrene-block-poly(ethylene oxide (PS-b-PEO copolymers as soft-templating agents. Nanoparticles synthesis was carried out in a mixed solvent system. After spin-coating onto a macroporous silicon nitride support, silica nanoparticles were calcined under controlled conditions. An organized nanoporous layer was obtained characterized by a depth filter-like structure with internal porosity due to interparticle voids. Permeability and size-selectivity were studied by monitoring the diffusion of probe molecules under standard conditions and under the application of an external stimulus (i.e., electric field. Promising results were obtained, suggesting possible applications of these nanoporous films as selective gates for controlled transport of chemical species in solution.

  14. Ultrafast laser induced electronic and structural modifications in bulk fused silica

    Energy Technology Data Exchange (ETDEWEB)

    Mishchik, K.; D' Amico, C.; Velpula, P. K.; Mauclair, C.; Boukenter, A.; Ouerdane, Y.; Stoian, R. [Laboratoire Hubert Curien, UMR 5516 CNRS, Université de Lyon, Université Jean Monnet, 42000 Saint Etienne (France)

    2013-10-07

    Ultrashort laser pulses can modify the inner structure of fused silica, generating refractive index changes varying from soft positive (type I) light guiding forms to negative (type II) values with void presence and anisotropic sub-wavelength modulation. We investigate electronic and structural material changes in the type I to type II transition via coherent and incoherent secondary light emission reflecting free carrier behavior and post-irradiation material relaxation in the index change patterns. Using phase contrast microscopy, photoluminescence, and Raman spectroscopy, we determine in a space-resolved manner defect formation, redistribution and spatial segregation, and glass network reorganization paths in conditions marking the changeover between type I and type II photoinscription regimes. We first show characteristic patterns of second harmonic generation in type I and type II traces, indicating the collective involvement of free carriers and polarization memory. Second, incoherent photoemission from resonantly and non-resonantly excited defect states reveals accumulation of non-bridging oxygen hole centers (NBOHCs) in positive index domains and oxygen deficiency centers (ODCs) with O{sub 2}{sup −} ions segregation in void-like regions and in the nanostructured domains, reflecting the interaction strength. Complementary Raman investigations put into evidence signatures of the different environments where photo-chemical densification (bond rearrangements) and mechanical effects can be indicated. NBOHCs setting in before visible index changes serve as precursors for subsequent compaction build-up, indicating a scenario of cold, defect-assisted densification for the soft type I irradiation regime. Additionally, we observe hydrodynamic effects and severe bond-breaking in type II zones with indications of phase transition. These observations illuminate densification paths in fused silica in low power irradiation regimes, and equally in energetic ranges

  15. Effect of Alkali-Silica Reaction on Shear Strength of Reinforced Concrete Structural Members

    Energy Technology Data Exchange (ETDEWEB)

    Hariri-Ardebili, Mohammad [Univ. of Colorado, Boulder, CO (United States); Saouma, Victor [Univ. of Colorado, Boulder, CO (United States); Le Pape, Yann [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-10-01

    Alkali-silica reaction (ASR) was discovered in the early 40s by Stanton (1940) of the California Division of Highways. Since, it has been recognized as a major degradation mechanism for concrete dams and transportation infrastructures. Sometimes described as the ’cancer of concrete’, this internal swelling mechanism causes expansion, cracking and loss of mechanical properties. There are no known economically viable solutions applicable to massive concrete to prevent the reaction once initiated. The e ciency of the mitigation strategies for ASR subjected structures is limited. Several cases of ASR in nuclear generating stations have been disclosed in Japan (Takatura et al. 2005), Canada at Gentilly 2 NPP (Tcherner and Aziz 2009) 1, and more recently, in the United States for which the U.S. Nuclear Regulatory Commission issued Information Notice (IN) 2011-20, ’Concrete Degradation by Alkali Silica Reaction,’ on November 18, 2011, to provide the industry with information related to the ASR identified at Seabrook. Considering that US commercial reactors in operation enter the age when ASR degradation can be visually detected and that numerous non nuclear infrastructures (transportation, energy production) have already experienced ASR in a large majority of the States (e.g., Department of Transportation survey reported by Touma (Touma 2000)), the susceptibility and significance of ASR for nuclear concrete structures must be addressed in the perspective of license renewal and long-term operation beyond 60 years. The aim of this report is to perform an extensive parametric series of 3D nonlinear finite element analyses of three di erent “beam-like” geometries, including two di erent depths, three di erent types of boundary conditions, and four other parameters: namely, the ASR volumetric expansion, the reinforcement ratio, the loss of elastic modulus induced by ASR and the loss of tensile strength caused by ASR.

  16. Measurement of valence band structure in arbitrary dielectric films

    International Nuclear Information System (INIS)

    Uhm, Han S.; Choi, Eun H.

    2012-01-01

    A new way of measuring the band structure of various dielectric materials using the secondary electron emission from Auger neutralization of ions is introduced. The first example of this measurement scheme is the magnesium oxide (MgO) films with respect to the application of the films in the display industries. The density of state in the valence bands of MgO film and MgO film with a functional layer (FL) deposited over a dielectric surface reveals that the density peak of film with a FL is considerably less than that of film, thereby indicating a better performance of MgO film with functional layer in display devices. The second example of the measurement is the boron-zinc oxide (BZO) films with respect to the application of the films to the development of solar cells. The measurement of density of state in BZO film suggests that a high concentration of boron impurity in BZO films may enhance the transition of electrons and holes through the band gap from the valence to the conduction band in zinc oxide crystals; thereby improving the conductivity of the film. Secondary electron emission by the Auger neutralization of ions is highly instrumental for the determination of the density of states in the valence band of dielectric materials.

  17. Film-thickness dependence of structure formation in ultra-thin polymer blend films

    CERN Document Server

    Gutmann, J S; Stamm, M

    2002-01-01

    We investigated the film-thickness dependence of structure formation in ultra-thin polymer blend films prepared from solution. As a model system we used binary blends of statistical poly(styrene-co-p-bromostyrene) copolymers of different degrees of bromination. Ultra-thin-film samples differing in miscibility and film thickness were prepared via spin coating of common toluene solutions onto silicon (100) substrates. The resulting morphologies were investigated with scanning force microscopy, reflectometry and grazing-incidence scattering techniques using both X-rays and neutrons in order to obtain a picture of the sample structure at and below the sample surface. (orig.)

  18. Temperature-dependent structural properties of P3HT films

    Energy Technology Data Exchange (ETDEWEB)

    Grigorian, S; Joshi, S; Pietsch, U, E-mail: grigorian@physik.uni-siegen.de [Institute of Physics, University Siegen, Walter Flex Strasse 3, D-57068, Siegen (Germany)

    2010-11-15

    Structural investigations of spin coated and drop cast poly(3-hexylthiophene) P3HT films have been performed under x-ray grazing incidence geometry. Drop cast films revealed to be highly oriented and crystalline and only slightly modify with the temperature. In contrast, spin coated films provided random orientational distribution of nanocrystallites and undergo significant morphological and structural changes during annealing. Interestingly, spin coated films of low and high molecular weight fractions behavior differently as a function of temperature. Crystalline domains of the low molecular weight fractions have been decreased, and, in contrast, we found an improvement of crystallinity of high molecular weight fraction with increase of the temperature.

  19. Temperature-dependent structural properties of P3HT films

    International Nuclear Information System (INIS)

    Grigorian, S; Joshi, S; Pietsch, U

    2010-01-01

    Structural investigations of spin coated and drop cast poly(3-hexylthiophene) P3HT films have been performed under x-ray grazing incidence geometry. Drop cast films revealed to be highly oriented and crystalline and only slightly modify with the temperature. In contrast, spin coated films provided random orientational distribution of nanocrystallites and undergo significant morphological and structural changes during annealing. Interestingly, spin coated films of low and high molecular weight fractions behavior differently as a function of temperature. Crystalline domains of the low molecular weight fractions have been decreased, and, in contrast, we found an improvement of crystallinity of high molecular weight fraction with increase of the temperature.

  20. Tailoring electronic structure of polyazomethines thin films

    OpenAIRE

    J. Weszka; B. Hajduk; M. Domański; M. Chwastek; J. Jurusik; B. Jarząbek; H. Bednarski; P. Jarka

    2010-01-01

    Purpose: The aim of this work is to show how electronic properties of polyazomethine thin films deposited by chemical vapor deposition method (CVD) can be tailored by manipulating technological parameters of pristine films preparation as well as modifying them while the as-prepared films put into iodine atmosphere.Design/methodology/approach: The recent achievements in the field of designing and preparation methods to be used while preparing polymer photovoltaic solar cells or optoelectronic ...

  1. Synthesis and new structure shaping mechanism of silica particles formed at high pH

    International Nuclear Information System (INIS)

    Zhang, Henan; Zhao, Yu; Akins, Daniel L.

    2012-01-01

    For the sol–gel synthesis of silica particles under high pH catalytic conditions (pH>12) in water/ethanol solvent, we have deduced that the competing dynamics of chemical etching and sol–gel process can explain the types of silica particles formed and their morphologies. We have demonstrated that emulsion droplets that are generated by adding tetraethyl orthosilicate (TEOS) to a water–ethanol solution serve as soft templates for hollow spherical silica (1–2 μm). And if the emulsion is converted by the sol–gel process, one finds that suspended solid silica spheres of diameter of ∼900 nm are formed. Moreover, several other factors are found to play fundamental roles in determining the final morphologies of silica particles, such as by variation of the pH (in our case, using OH – ) to a level where condensation dominates; by changing the volume ratios of water/ethanol; and using an emulsifier (specifically, CTAB) - Graphical abstract: “Local chemical etching” and sol–gel process have been proposed to interpret the control of morphologies of silica particles through varying initial pHs in syntheses. Highlights: ► Different initial pHs in our syntheses provides morphological control of silica particles. ► “Local chemical etching” and sol–gel process describes the formation of silica spheres. ► The formation of emulsions generates hollow silica particles.

  2. Facile fabrication of superhydrophobic films with fractal structures using epoxy resin microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Quan, Yun-Yun; Zhang, Li-Zhi, E-mail: lzzhang@scut.edu.cn

    2014-02-15

    A simple method has been developed to fabricate superhydrophobic surfaces with fractal structures with epoxy resin microspheres (ERMs). The ERMs is produced by phase separation in an epoxy-amine curing system with a silica sol (SS) dispersant. The transparent epoxy solution becomes cloudy and turns into epoxy suspension (ES) in this process. The fractal structure (two tier structure) generated by synthetic epoxy resin microspheres (ERMs) and deposited nanoincrutations on the surfaces of these ERMs, which have been observed by scanning electron microscope (SEM). The curing time of ES is an important condition to obtain films with good comprehensive performances. Superhydrophobic films can be prepared by adding extra SS into ES with a curing time longer than 5 h. The optimal curing time is 10 h to fabricate a film with good mechanical stability and high superhydrophobicity. In addition, a surface with anti-wetting property of impacting microdroplets can be fabricated by prolonging the curing time of ES to 24 h. The gradually decreased hydrophilic groups resulted from a longer curing time enable the surface to have smaller surface adhesions to water droplets, which is the main reason to keep its superhydrophobicity under impacting conditions. The coated surface is highly hydrophobic and the impacting water droplets are bounced off from the surface.

  3. Facile fabrication of superhydrophobic films with fractal structures using epoxy resin microspheres

    Science.gov (United States)

    Quan, Yun-Yun; Zhang, Li-Zhi

    2014-02-01

    A simple method has been developed to fabricate superhydrophobic surfaces with fractal structures with epoxy resin microspheres (ERMs). The ERMs is produced by phase separation in an epoxy-amine curing system with a silica sol (SS) dispersant. The transparent epoxy solution becomes cloudy and turns into epoxy suspension (ES) in this process. The fractal structure (two tier structure) generated by synthetic epoxy resin microspheres (ERMs) and deposited nanoincrutations on the surfaces of these ERMs, which have been observed by scanning electron microscope (SEM). The curing time of ES is an important condition to obtain films with good comprehensive performances. Superhydrophobic films can be prepared by adding extra SS into ES with a curing time longer than 5 h. The optimal curing time is 10 h to fabricate a film with good mechanical stability and high superhydrophobicity. In addition, a surface with anti-wetting property of impacting microdroplets can be fabricated by prolonging the curing time of ES to 24 h. The gradually decreased hydrophilic groups resulted from a longer curing time enable the surface to have smaller surface adhesions to water droplets, which is the main reason to keep its superhydrophobicity under impacting conditions. The coated surface is highly hydrophobic and the impacting water droplets are bounced off from the surface.

  4. IR-spectroscopical investigations on the glass structure of porous and sintered compacts of colloidal silica gels

    Science.gov (United States)

    Clasen, Rolf; Hornfeck, M.; Theiss, Wolfgang

    1991-08-01

    The forming and sintering of fumed silica powders is an interesting route for the preparation of large, very pure or doped silica glasses with a precise geometry. The processing from the shaping of a porous compact to the sintering of transparent silica glass can be successfully investigated with optical spectroscopy. As only the dielectric function DF (a dielectric function is the square root of the complex refractive index) characterizes the material, the vibrational bands were calculated from reflectance measurements. In compacts of fine particles, the topology cannot be neglected. Therefore, the models describing topological effects are briefly reviewed. With these model calculations it could be proven that new bands in the compacts and the significant shifts in the reflectance spectra during sintering are mainly caused by topological effects and that changes in the glass structure play only a secondary role.

  5. Effect of nitrogen incorporation on the structural, optical and dielectric properties of reactive sputter grown ITO films

    Energy Technology Data Exchange (ETDEWEB)

    Gartner, M.; Stroescu, H. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Marin, A., E-mail: alexmarin@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Osiceanu, P. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Anastasescu, M., E-mail: manastasescu@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Stoica, M.; Nicolescu, M.; Duta, M.; Preda, S. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Aperathitis, E.; Pantazis, A.; Kampylafka, V. [FORTH-IESL, Crete (Greece); Modreanu, M. [Tyndall National Institute, University College Cork, Cork (Ireland); Zaharescu, M. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania)

    2014-09-15

    Highlights: • Graded optical model for ITON films is presented. • ITON thin films retain an amorphous structure even after RTA at 500 °C in N{sub 2} ambient. • The lowest resistivity was 2 × 10{sup −3} Ω cm for films deposited in 75%N{sub 2} and RTA at 500 °C. • Films deposited in 75% N{sub 2} and RTA at 500 °C have degenerate semiconductor behavior. • Chemical composition before and after RTA has been analyzed by XPS depth profiling. - Abstract: The changes in the optical, microstructural and electrical properties, following the nitrogen incorporation into indium tin oxide thin films are investigated. The films are formed by r.f. sputtering from an indium-tin-oxide (80% In{sub 2}O{sub 3}–20% SnO{sub 2}) target in a mixture of Ar and N{sub 2} plasma (75% N{sub 2}–25% Ar and 100% N{sub 2} respectively) on fused silica glass substrate. The impact of rapid thermal annealing (up to 500 °C, in N{sub 2} ambient) on the properties of indium tin oxynitride (ITON) thin films is also reported. The UV–vis–NIR ellipsometry (SE) characterization of ITON films was performed assuming several realistic approaches based on various oscillator models, using a chemical composition gradient depth profiling, in agreement with the X-ray photoelectron spectroscopy measurements. The Hall measurements show that the ITON films prepared by r.f. sputtering in 75% N{sub 2} and annealed at 500 °C behave as degenerate semiconductors. X-ray diffraction analysis proved that ITON thin films retain an amorphous structure even after RTA at 500 °C in N{sub 2} ambient and atomic force microscopy showed the formation of continuous and smooth ITON thin films, with a morphology consisting in quasispherical nanometric particles.

  6. Structure and oxygen incorporation in low pressure sputtered YBCO films

    International Nuclear Information System (INIS)

    Chaudhary, S.; Pandya, D. K.; Kashyap, S. C.

    2002-01-01

    Thin films of YBa 2 Cu 3 O 7- δ (YBCO) have been successfully grown by reactive RF-magnetron sputtering technique at low pressure. The oxygen partial pressure of 0.95 mTorr, a total pressure (argon and oxygen) of 1.9 mTorr, and a substrate temperature of 775 grad C resulted in good quality films with T C (R=0) = 85.3 K and J Cmag (4.2 K) ≅ 2x10 7 A/cm 2 . The incorporation of oxygen in the as-grown films has been controlled by using different ambient - oxygen, air or argon during in-situ cooling. The superconducting behaviour of the films was studied using resistance-temperature and low field ac-susceptibility measurements and correlated with their structure. All the films exhibited metallic conduction in the normal state. The oxygen- and air- cooled films were superconducting, possessing the usual orthorhombic structure. The argon-cooled films were non-superconducting possessing the tetragonal structure, thus implying that the structure of the film during deposition is tetragonal which transforms to either of the oxygen rich orthorhombic-I or -II phases depending upon the oxygen/air ambient. The 'δ' values of 0.14, 0.32 and 0.70 and higher 'c'-parameters of 1.1785, 1.180 and 1.183 nm have been obtained for oxygen, air and argon cooled films respectively. (Authors)

  7. Crystal structure and thin film morphology of BBL ladder polymer

    Energy Technology Data Exchange (ETDEWEB)

    Song, H H [Department of Macromolecular Science, Han Nam University, Taejon (Korea, Republic of); Fratini, A V [Department of Chemistry, University of Dayton, Dayton, OH (United States); Chabinyc, M [Department of Chemistry, University of Dayton, Dayton, OH (United States); Price, G E [University of Dayton Research, Dayton, OH (United States); Agrawal, A K [Systran Corporation, Dayton, OH (United States); Wang, C S [University of Dayton Research, Dayton, OH (United States); Burkette, J [University of Dayton Research, Dayton, OH (United States); Dudis, D S [Materials Directorate, Wright Laboratory, Wright-Patterson Air Force Base, OH (United States); Arnold, F E [Materials Directorate, Wright Laboratory, Wright-Patterson Air Force Base, OH (United States)

    1995-03-01

    Crystal structure and morphology of poly[7-oxo-7H-benz(d,e)imidazo(4`,5`:5,6)-benzimidazo(2,1-a)isoquinoline-3,4:10,11-tetrayl-10-carbonyl] (BBL) ladder-like polymer were studied. The polymer forms a two-dimensional lattice of nematic liquid crystalline structure. An orthorhombic unit cell with cell parameters of a=7.87 b=3.37 c=11.97A was determined from the fiber diffraction pattern. In thin films, the rigid chains spontaneously form a layered structure across the film thickness, but in a very unusual manner, i.e. the very large molecular plane is standing perpendicularly to the film surface plane. The results are identical to our recent results of poly(p-phenylene benzobisthiazole) (PBT) film [7]. The polymer, however, lost its anisotropic order upon extrusion into a film and resulted in a fiber-like structure. (orig.)

  8. Structural Stability of Light-harvesting Protein LH2 Adsorbed on Mesoporous Silica Supports.

    Science.gov (United States)

    Shibuya, Yuuta; Itoh, Tetsuji; Matsuura, Shun-ichi; Yamaguchi, Akira

    2015-01-01

    In the present study, we examined the reversible thermal deformation of the membrane protein light-harvesting complex LH2 adsorbed on mesoporous silica (MPS) supports. The LH2 complex from Thermochromatium tepidum cells was conjugated to MPS supports with a series of pore diameter (2.4 to 10.6 nm), and absorption spectra of the resulting LH2/MPS conjugates were observed over a temperature range of 273 - 313 K in order to examine the structure of the LH2 adsorbed on the MPS support. The experimental results confirmed that a slight ellipsoidal deformation of LH2 was induced by adsorption on the MPS supports. On the other hand, the structural stability of LH2 was not perturbed by the adsorption. Since the pore diameter of MPS support did not influence the structural stability of LH2, it could be considered that the spatial confinement of LH2 in size-matches pore did not improve the structural stability of LH2.

  9. D. C. plasma-sprayed coatings of nano-structured alumina-titania-silica

    International Nuclear Information System (INIS)

    Jiang Xianliang

    2002-01-01

    nano-crystalline powders of ω(Al 2 O 3 ) = 95%, ω(TiO 2 ) = 3%, and ω(SiO 2 ) = 2%, were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps of ball milling, slurry forming, spray drying, and heat treatment. D.C. plasma was used to spray the agglomerated nano-crystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Experimental results show that the agglomerated nano-crystalline particles are spherical, with a size from (10-90) μm. The flow ability of the nano-crystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nano-structure. Unlike conventional plasma-sprayed coatings, no laminar layer could be found in the nano-structured coatings. Although the nano-structured coatings have a lower microhardness than conventional microstructured coatings, the toughness of the nano-structured ceramic coatings is significantly improved

  10. Surface texture modification of spin-coated SiO2 xerogel thin films ...

    Indian Academy of Sciences (India)

    hydrolysis and condensation of tetraethylorthosilicate (TEOS) with ethanol as a solvent. Further, the deposited thin films were ... termed as hydrolysis and condensation that occur simultane- ously in the formation of silica films. ... rial leads to capillary tensions, which destroy the structure of silica (Naik and Ghosh 2009).

  11. Infrared Spectroscopic Study on Structural Change and Interfacial Interaction in Rubber Composites Filled with Silica-Kaolin Hybrid Fillers

    Science.gov (United States)

    Chen, Y.; Guan, J.; Hu, H.; Gao, H.; Zhang, L.

    2016-07-01

    A series of natural rubber/styrene butadiene rubber/polybutadiene rubber composites was prepared with nanometer silica and micron kaolin by a dry modification process, mechanical compounding, and mold vulcanization. Fourier transform infrared spectroscopy and a scanning electron microscope were used to investigate the structural changes and interfacial interactions in composites. The results showed that the "seesaw" structure was formed particularly with the incorporation of silica particles in the preparation process, which would be beneficial to the dispersibility of fillers in the rubber matrix. The kaolinite platelets were generally arranged in directional alignment. Kaolinite with smaller particle size and low-defect structure was more stable in preparation, but kaolinite with larger particle size and high defect structure tended to change the crystal structure. The composite prepared in this research exhibited excellent mechanical and thermal properties.

  12. Advanced Structural Characterization of Organic Thin Films

    DEFF Research Database (Denmark)

    Gu, Yun

    of small molecule and polymer layers is indicated by Flory- Huggins theory for the triisopropylsilylethynl pentacene (TIPS-PEN) and polystyrene blend films. In order to investigate the phase separated layers in the ink-jet printed films, we propose a method to measure diraction Bragg peaks by X...

  13. Novel structuring routines of titania films for application in photovoltaics

    OpenAIRE

    Niedermeier, Martin A.

    2014-01-01

    Novel routines to structure titania thin films on various length scales are investigated regarding photovoltaic applications. The main focus of the investigations lies on the custom-tailoring of the morphologies of the titania films using sol-gel chemistry in combination with block copolymer templating. Additionally, a low-temperature routine for functional hybrid films as well as the growth of gold as electrode material on top of an organic hole-conductor are investigated. Im Hinblick auf...

  14. D. C. plasma-sprayed coatings of nano-structured alumina-titania-silica

    CERN Document Server

    Jiang Xian Liang

    2002-01-01

    nano-crystalline powders of omega(Al sub 2 O sub 3) = 95%, omega(TiO sub 2) = 3%, and omega(SiO sub 2) = 2%, were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps of ball milling, slurry forming, spray drying, and heat treatment. D.C. plasma was used to spray the agglomerated nano-crystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Experimental results show that the agglomerated nano-crystalline particles are spherical, with a size from (10-90) mu m. The flow ability of the nano-crystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nano-structure. Unlike conventional plasma-sprayed coatings, no laminar layer could be found in the nano-structured coatings. Although the nano-structured coatings have a lo...

  15. Durable Lotus-effect surfaces with hierarchical structure using micro- and nanosized hydrophobic silica particles.

    Science.gov (United States)

    Ebert, Daniel; Bhushan, Bharat

    2012-02-15

    Surfaces with a very high apparent water contact angle (CA) and low water contact angle hysteresis (CAH) exhibit many useful characteristics, among them extreme water repellency, low drag for fluid flow, and a self-cleaning effect. The leaf of the Lotus plant (Nelumbo nucifera) achieves these properties using a hierarchical structure with roughness on both the micro- and nanoscale. It is of great interest to create durable surfaces with the so-called "Lotus effect" for many important applications. In this study, hierarchically structured surfaces with Lotus-effect properties were fabricated using micro- and nanosized hydrophobic silica particles and a simple spray method. In addition, hierarchically structured surfaces were prepared by spraying a nanoparticulate coating over a micropatterned surface. To examine the similarities between surfaces using microparticles versus a uniform micropattern as the microstructure, CA and CAH were compared across a range of pitch values for the two types of microstructures. Wear experiments were performed using an atomic force microscope (AFM), a ball-on-flat tribometer, and a water jet apparatus to verify multiscale wear resistance. These surfaces have potential uses in engineering applications requiring Lotus-effect properties and high durability. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Study on the influence of Alkali-Silica reaction on structural behavior of reinforced concrete members

    International Nuclear Information System (INIS)

    Murazumi, Y.; Watanabe, Y.; Matsumoto, N.; Mitsugi, S.; Takiguchi, K.; Masuda, Y.

    2005-01-01

    Expansion produced by alkali-silica reaction (ASR) has been observed in the turbine generator foundation of the unit 1, Ikata nuclear power station, Japan. The foundation is a reinforced concrete frame structure. This paper, as a part of the series of investigation and experiments, discusses tests on structural behavior of concrete members affected by ASR. The purpose of the study is to obtain experimental results on the effects of ASR on bending and shear behavior of reinforced concrete beams and shear walls, and compare with the calculated results by present evaluation methods for normal concrete structures For the experiments on bending/shear behavior of beam, bending test models with a small amount of rebar and shear test models with larger amount were made of concrete in which ASR was induced by adding alkali or concrete without ASR. It was found from the results that bending strength of the bending test models and shear strength of the shear test models did not fall, nor was it lower than the calculated strength for concrete members without ASR. In the shear wall test, the two test models were made of either concrete with ASR or one without it. Horizontal load was applied with actuators on the test model fixed on the test floor, while vertical load was applied with oil jacks. The results did not indicate that ASR lowered the stiffness or strength of the wall test models, showing the strength was able to be calculated with the same formula for reinforced concrete wall without ASR. (authors)

  17. Spontaneous phase transitions in magnetic films with a modulated structure

    International Nuclear Information System (INIS)

    Arzamastseva, G. V.; Evtikhov, M. G.; Lisovskii, F. V.; Mansvetova, E. G.

    2011-01-01

    The influence of monoperiodic and biperiodic bias fields on the nucleation of domain structures in quasi-uniaxial magnetic films near the Curie point has been studied experimentally. The main types of observed nonuniform magnetic moment distributions have been established and chains of a devil’s staircase phase transitions are shown to be realized when the films are slowly cooled.

  18. Structural evolution, electrical and optical properties of AZO films ...

    Indian Academy of Sciences (India)

    Administrator

    Aluminum-doped zinc oxide (AZO) target was fabricated using AZO ... All AZO films show c-axis preferred orientation and hexagonal structure. With increasing film thick- ness from 153 to 1404 nm, the crystallinity was improved and the angle of (002) peak was close to ... For observing grain boundary and size, the target was.

  19. Encapsulation of dye molecules into mesoporous polymer resin and mesoporous polymer-silica films by an evaporation-induced self-assembly method

    Energy Technology Data Exchange (ETDEWEB)

    Chi Yue; Li Nan; Tu Jinchun; Zhang Yujie [School of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, Changchun 130012 (China); Li Xiaotian, E-mail: xiaotianli@jlu.edu.c [School of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, Changchun 130012 (China); Shao Changlu, E-mail: clshao@nenu.edu.c [Center for Advanced Optoelectronic Functional Materials Research, Northeast Normal University, Changchun 130024 (China)

    2010-03-15

    Polymer resin and polymer-silica films with highly ordered mesostructure have been used as host materials to encapsulate DCM (4-(dicyanomethylene) -2-methyl-6-(4-dimethylaminostyryl)-4h-pyran), a kind of fluorescent dye, through evaporation-induced self-assembly method (EISA). After encapsulation, the composites show significant blue-shift in photoluminescence (PL) spectra. Particularly, by changing the excitation wavelength, the samples show different emission bands. These phenomena are related to the mesostructure and the positions of DCM molecules in the host.

  20. Encapsulating Silica/Antimony into Porous Electrospun Carbon Nanofibers with Robust Structure Stability for High-Efficiency Lithium Storage.

    Science.gov (United States)

    Wang, Hongkang; Yang, Xuming; Wu, Qizhen; Zhang, Qiaobao; Chen, Huixin; Jing, Hongmei; Wang, Jinkai; Mi, Shao-Bo; Rogach, Andrey L; Niu, Chunming

    2018-04-24

    To address the volume-change-induced pulverization problems of electrode materials, we propose a "silica reinforcement" concept, following which silica-reinforced carbon nanofibers with encapsulated Sb nanoparticles (denoted as SiO 2 /Sb@CNFs) are fabricated via an electrospinning method. In this composite structure, insulating silica fillers not only reinforce the overall structure but also contribute to additional lithium storage capacity; encapsulation of Sb nanoparticles into the carbon-silica matrices efficiently buffers the volume changes during Li-Sb alloying-dealloying processes upon cycling and alleviates the mechanical stress; the porous carbon nanofiber framework allows for fast charge transfer and electrolyte diffusion. These advantageous characteristics synergistically contribute to the superior lithium storage performance of SiO 2 /Sb@CNF electrodes, which demonstrate excellent cycling stability and rate capability, delivering reversible discharge capacities of 700 mA h/g at 200 mA/g, 572 mA h/g at 500 mA/g, and 468 mA h/g at 1000 mA/g each after 400 cycles. Ex situ as well as in situ TEM measurements confirm that the structural integrity of silica-reinforced Sb@CNF electrodes can efficiently withstand the mechanical stress induced by the volume changes. Notably, the SiO 2 /Sb@CNF//LiCoO 2 full cell delivers high reversible capacities of ∼400 mA h/g after 800 cycles at 500 mA/g and ∼336 mA h/g after 500 cycles at 1000 mA/g.

  1. Subnanopore filling during water vapor adsorption on microporous silica thin films as seen by low-energy positron annihilation

    Science.gov (United States)

    Ito, Kenji; Yoshimoto, Shigeru; O'Rourke, Brian E.; Oshima, Nagayasu; Kumagai, Kazuhiro

    2018-02-01

    Positron annihilation lifetime spectroscopy (PALS) using a low-energy positron microbeam extracted into air was applied to elucidating molecular-level pore structures formed in silicon-oxide-backboned microporous thin films under controlled humidity conditions; as a result, a direct observation of the interstitial spaces in the micropores filled with water molecules was achieved. It was demonstrated that PALS using a microbeam extracted into air in combination with water vapor adsorption is a powerful tool for the in-situ elucidation of both open and closed subnanoscaled pores of functional thin materials under practical conditions.

  2. Geometric shape control of thin film ferroelectrics and resulting structures

    Science.gov (United States)

    McKee, Rodney A.; Walker, Frederick J.

    2000-01-01

    A monolithic crystalline structure and a method of making involves a semiconductor substrate, such as silicon, and a ferroelectric film, such as BaTiO.sub.3, overlying the surface of the substrate wherein the atomic layers of the ferroelectric film directly overlie the surface of the substrate. By controlling the geometry of the ferroelectric thin film, either during build-up of the thin film or through appropriate treatment of the thin film adjacent the boundary thereof, the in-plane tensile strain within the ferroelectric film is relieved to the extent necessary to permit the ferroelectric film to be poled out-of-plane, thereby effecting in-plane switching of the polarization of the underlying substrate material. The method of the invention includes the steps involved in effecting a discontinuity of the mechanical restraint at the boundary of the ferroelectric film atop the semiconductor substrate by, for example, either removing material from a ferroelectric film which has already been built upon the substrate, building up a ferroelectric film upon the substrate in a mesa-shaped geometry or inducing the discontinuity at the boundary by ion beam deposition techniques.

  3. In situ crystallization of b-oriented MFI films on plane and curved substrates coated with a mesoporous silica layer

    KAUST Repository

    Deng, Zhiyong; Pera-Titus, Marc

    2013-01-01

    a silica source to promote the nucleation and growth of zeolite crystals via a heterogeneous nucleation mechanism (zeolitization), and adsorb zeolite moieties generated in the synthesis solution via a homogeneous nucleation mechanism. A monolayer

  4. P-type CuxS thin films: Integration in a thin film transistor structure

    International Nuclear Information System (INIS)

    Nunes de Carvalho, C.; Parreira, P.; Lavareda, G.; Brogueira, P.; Amaral, A.

    2013-01-01

    Cu x S thin films, 80 nm thick, are deposited by vacuum thermal evaporation of sulfur-rich powder mixture, Cu 2 S:S (50:50 wt.%) with no intentional heating of the substrate. The process of deposition occurs at very low deposition rates (0.1–0.3 nm/s) to avoid the formation of Cu or S-rich films. The evolution of Cu x S films surface properties (morphology/roughness) under post deposition mild annealing in air at 270 °C and their integration in a thin film transistor (TFT) are the main objectives of this study. Accordingly, Scanning Electron Microscopy studies show Cu x S films with different surface morphologies, depending on the post deposition annealing conditions. For the shortest annealing time, the Cu x S films look to be constructed of grains with large dimension at the surface (approximately 100 nm) and consequently, irregular shape. For the longest annealing time, films with a fine-grained surface are found, with some randomly distributed large particles bound to this fine-grained surface. Atomic Force Microscopy results indicate an increase of the root-mean-square roughness of Cu x S surface with annealing time, from 13.6 up to 37.4 nm, for 255 and 345 s, respectively. The preliminary integration of Cu x S films in a TFT bottom-gate type structure allowed the study of the feasibility and compatibility of this material with the remaining stages of a TFT fabrication as well as the determination of the p-type characteristic of the Cu x S material. - Highlights: • Surface properties of annealed Cu x S films. • Variation of conductivity with annealing temperatures of Cu x S films. • Application of evaporated Cu x S films in a thin film transistor (TFT) structure. • Determination of Cu x S p-type characteristic from TFT behaviour

  5. Water-insoluble Silk Films with Silk I Structure

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Q.; Hu, X; Wang, X; Kluge, J; Lu, S; Cebe, P; Kaplan, D

    2010-01-01

    Water-insoluble regenerated silk materials are normally produced by increasing the {beta}-sheet content (silk II). In the present study water-insoluble silk films were prepared by controlling the very slow drying of Bombyx mori silk solutions, resulting in the formation of stable films with a predominant silk I instead of silk II structure. Wide angle X-ray scattering indicated that the silk films stabilized by slow drying were mainly composed of silk I rather than silk II, while water- and methanol-annealed silk films had a higher silk II content. The silk films prepared by slow drying had a globule-like structure at the core surrounded by nano-filaments. The core region was composed of silk I and silk II, surrounded by hydrophilic nano-filaments containing random turns and {alpha}-helix secondary structures. The insoluble silk films prepared by slow drying had unique thermal, mechanical and degradative properties. Differential scanning calorimetry results revealed that silk I crystals had stable thermal properties up to 250 C, without crystallization above the T{sub g}, but degraded at lower temperatures than silk II structure. Compared with water- and methanol-annealed films the films prepared by slow drying had better mechanical ductility and were more rapidly enzymatically degraded, reflecting the differences in secondary structure achieved via differences in post processing of the cast silk films. Importantly, the silk I structure, a key intermediate secondary structure for the formation of mechanically robust natural silk fibers, was successfully generated by the present approach of very slow drying, mimicking the natural process. The results also point to a new mode of generating new types of silk biomaterials with enhanced mechanical properties and increased degradation rates, while maintaining water insolubility, along with a low {beta}-sheet content.

  6. Effect of sintering on crystallization and structural properties of soda lime silica glass

    Directory of Open Access Journals (Sweden)

    Zaid Mohd Hafiz Mohd

    2017-01-01

    Full Text Available The effect of sintering temperatures on crystallization and structural of the soda lime silica (SLS glass was reported. Elemental weight composition of the SLS glass powder was identified through Energy dispersive X-ray fluorescence (EDXRF analysis while the thermal behavior of the glass was determined using Differential thermal analysis (DTA technique. Archimedes’ method and direct geometric measurement were respectively used to determine bulk density and linear shrinkage of the glass samples. Crystallisation behavior of the samples was investigated by X-ray diffraction (XRD analysis and chemical bonds present in the samples were measured using Fourier Transform Infrared (FTIR spectroscopy. Results showed an increase in the density and linear shrinkage of the samples as a function of the sintering temperature. The XRD analysis revealed the formation of α-quartz (SiO2 and a minor amount of devitrite phases in the samples and these were further verified through the detection of chemical bonds by FTIR after sintering at 800ºC. The properties of the glass-ceramics can be explained on the basis of crystal chemistry which indicated that the alkali ions formed as carriers in the random network structure and can be recommended for the manufacture of glass fiber or toughened glass-ceramic insulators.

  7. Structural and optical properties of Eu3+ activated low cost zinc soda lime silica glasses

    Directory of Open Access Journals (Sweden)

    Nur Alia Sheh Omar

    Full Text Available A low cost method was employed to synthesize ZnO-SLS:xEu3+ phosphors using recyclable bottle glass as silica source. The structural and optical properties of ZnO-SLS:xEu3+ (x = 0, 1, 2, 3, 4 and 5 wt.% glasses were determined using X-ray diffraction (XRD, Fourier transform infrared reflectance (FTIR, UV-visible (Uv-Vis and photoluminescence (PL spectroscopy. Structural investigation using XRD measurement had broadened the halo peak with the doping of dopants. FTIR spectra showed the glass system consists of –OH and SiO4 bands. Meanwhile, the optical measurement using UV-Vis absorption has been induced a blue shift of the electronic absorption edge. The emission peak intensity of ZnO-SLS:xEu3+ phosphors was enhanced with the progression of doping concentration and thus, revealed their potential as red emitting phosphors under 400 nm excitation. Keywords: Eu3+ doped ZnO-SLS glasses, Solid state method, Optical band gap, Photoluminescence

  8. Ion beam-based characterization of multicomponent oxide thin films and thin film layered structures

    International Nuclear Information System (INIS)

    Krauss, A.R.; Rangaswamy, M.; Lin, Yuping; Gruen, D.M.; Schultz, J.A.; Schmidt, H.K.; Chang, R.P.H.

    1992-01-01

    Fabrication of thin film layered structures of multi-component materials such as high temperature superconductors, ferroelectric and electro-optic materials, and alloy semiconductors, and the development of hybrid materials requires understanding of film growth and interface properties. For High Temperature Superconductors, the superconducting coherence length is extremely short (5--15 Angstrom), and fabrication of reliable devices will require control of film properties at extremely sharp interfaces; it will be necessary to verify the integrity of thin layers and layered structure devices over thicknesses comparable to the atomic layer spacing. Analytical techniques which probe the first 1--2 atomic layers are therefore necessary for in-situ characterization of relevant thin film growth processes. However, most surface-analytical techniques are sensitive to a region within 10--40 Angstrom of the surface and are physically incompatible with thin film deposition and are typically restricted to ultra high vacuum conditions. A review of ion beam-based analytical methods for the characterization of thin film and multi-layered thin film structures incorporating layers of multicomponent oxides is presented. Particular attention will be paid to the use of time-of-flight techniques based on the use of 1- 15 key ion beams which show potential for use as nondestructive, real-time, in-situ surface diagnostics for the growth of multicomponent metal and metal oxide thin films

  9. The structure heterogeneity of silica mesopores of Sba-15 in respect to the pluronic 123 template concentration

    Science.gov (United States)

    Dhaneswara, D.; Fatriansyah, J. F.; Putranto, D. A.; Utami, S. A. A.; Delayori, F.

    2018-01-01

    The analysis of structure heterogeneity factor of silica mesoporous SBA-15 has been conducted. The structure factor has been found to be different for low and high concentration of Pluronic-123 template. The structure heterogeneity of high concentration of Pluronic-123 has been found less than 1 while for low concentration, the structure heterogeneity was found to be larger than 1. This indicates the dissimilarity of the structure and can be used as a probe to detect the formation of large mesopores. It also was found that the system exhibits type IV and H1 adsorption type which indicates the capillary condensation and interconnected pores.

  10. Fabrication of polystyrene porous films with gradient pore structures

    International Nuclear Information System (INIS)

    Yan Hongwei; Zhang Lin; Li Bo; Yin Qiang

    2010-01-01

    Silica opals and multilayer heterostructures were fabricated by vertical deposition technique. Polystyrene inverse opals and gradient porous structures were obtained by colloidal templating, in order to control the pore microstructure of polymer porous materials. As shown in the scanning electron microscopy images, the polystyrene porous structures are precise replicas of inverse structures of the original templates. After being infiltrated with the polystyrene, the photonic stop-band position of the opal composite is redshifted compared with the original template, and it is blueshifted after the opal template being removed. The filling ratio of polystyrene was calculated according to the Bragg formula. (authors)

  11. Microporous silica membranes

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Yue, Yuanzheng

    2012-01-01

    Hydrothermal stability is a crucial factor for the application of microporous silica-based membranes in industrial processes. Indeed, it is well established that steam exposure may cause densification and defect formation in microporous silica membranes, which are detrimental to both membrane...... permeability and selectivity. Numerous previous studies show that microporous transition metal doped-silica membranes are hydrothermally more stable than pure silica membranes, but less permeable. Here we present a quantitative study on the impact of type and concentration of transition metal ions...... on the microporous structure, stability and permeability of amorphous silica-based membranes, providing information on how to design chemical compositions and synthetic paths for the fabrication of silica-based membranes with a well accessible and highly stabile microporous structure....

  12. Structural and optical characterization of the propolis films

    Energy Technology Data Exchange (ETDEWEB)

    Drapak, S.I. [Frantsevich Institute of Materials Science Problems, National Academy of Sciences of Ukraine, Chernivtsi Department, 5 Iryna Vilde Str., 58001 Chernivtsi (Ukraine)]. E-mail: drapak@unicom.cv.ua; Bakhtinov, A.P. [Frantsevich Institute of Materials Science Problems, National Academy of Sciences of Ukraine, Chernivtsi Department, 5 Iryna Vilde Str., 58001 Chernivtsi (Ukraine); Gavrylyuk, S.V. [Frantsevich Institute of Materials Science Problems, National Academy of Sciences of Ukraine, Chernivtsi Department, 5 Iryna Vilde Str., 58001 Chernivtsi (Ukraine); Drapak, I.T. [Chernivtsi National University, 2 Kotsyubynskii Str., 58012 Chernivtsi (Ukraine); Kovalyuk, Z.D. [Frantsevich Institute of Materials Science Problems, National Academy of Sciences of Ukraine, Chernivtsi Department, 5 Iryna Vilde Str., 58001 Chernivtsi (Ukraine)

    2006-10-31

    We have performed structural and optical characterizations of the propolis (an organic entity of biological nature) films grown on various non-organic substrates. The films were grown from a propolis melt or a propolis alcohol solution. The crystal structure has been observed in the films precipitated from the solution onto substrates such as an amorphous glass and sapphire or semiconductor indium monoselenide. For any growth method, the propolis film is a semiconductor with the bandgap of 3.07 eV at 300 K that is confirmed by a maximum in photoluminescence spectra at 2.86 eV. We argue that propolis films might be used in various optoelectronic device applications.

  13. The influence of the matrix structure on the oxidation of aniline in a silica sol-gel composite

    International Nuclear Information System (INIS)

    Widera, J.; Kijak, A.M.; Ca, D.V.; Pacey, G.E.; Taylor, R.T.; Perfect, H.; Cox, J.A.

    2005-01-01

    Mesoporous and microporous silica matrices were formed on indium tin oxide electrodes for liquid-phase voltammetry and as monoliths for solid-state voltammetry of aniline. The pore structure, which was verified by scanning probe microscopy and by surface area measurement, was directed by either control of pH during sol-gel processing or by inclusion of a templating agent. Whether aniline was included as a dopant in the sol-gel or as a component of the contacting liquid, the pore size influenced the coupling of the product of its electrochemical oxidation. With microporous silica, the dominant products were dimers and related short-chain products whereas with mesoporous silica, polymerization was suggested. As a step toward the formation of polyaniline (PANI) that is covalently anchored to the sol-gel, the electrochemistry of aniline was investigated using composites prepared from sols comprising tetraethyl orthosilicate (TEOS), 3-aminophenyl-[3-triethoxylsilyl)-propyl] urea (ormosil), and aniline in various ratios. Combinatorial chemistry identified that the optimum combination of silica precursors in terms of obtaining PANI was a 1:12 mole ratio of ormosil:TEOS

  14. Fumed silica. Fumed silica

    Energy Technology Data Exchange (ETDEWEB)

    Sukawa, T.; Shirono, H. (Nippon Aerosil Co. Ltd., Tokyo (Japan))

    1991-10-18

    The fumed silica is explained in particulate superfineness, high purity, high dispersiveness and other remarkable characteristics, and wide application. The fumed silica, being presently produced, is 7 to 40nm in average primary particulate diameter and 50 to 380m{sup 2}/g in specific surface area. On the surface, there coexist hydrophilic silanol group (Si-OH) and hydrophobic siloxane group (Si-O-Si). There are many characteristics, mutually different between the fumed silica, made hydrophobic by the surface treatment, and untreated hydrophilic silica. The treated silica, if added to the liquid product, serves as agent to heighten the viscosity, prevent the sedimentation and disperse the particles. The highest effect is given to heighten the viscosity in a region of 4 to 9 in pH in water and alcohol. As filling agent to strengthen the elastomer and polymer, and powder product, it gives an effect to prevent the consolidation and improve the fluidity. As for its other applications, utilization is made of particulate superfineness, high purity, thermal insulation properties and adsorption characteristics. 2 to 3 patents are published for it as raw material of quartz glass. 38 refs., 16 figs., 4 tabs.

  15. Rupture of thin liquid films on structured surfaces.

    Science.gov (United States)

    Ajaev, Vladimir S; Gatapova, Elizaveta Ya; Kabov, Oleg A

    2011-10-01

    We investigate stability and breakup of a thin liquid film on a solid surface under the action of disjoining pressure. The solid surface is structured by parallel grooves. Air is trapped in the grooves under the liquid film. Our mathematical model takes into account the effect of slip due to the presence of menisci separating the liquid film from the air inside the grooves, the deformation of these menisci due to local variations of pressure in the liquid film, and nonuniformities of the Hamaker constant which measures the strength of disjoining pressure. Both linear stability and strongly nonlinear evolution of the film are analyzed. Surface structuring results in decrease of the fastest growing instability wavelength and the rupture time. It is shown that a simplified description of film dynamics based on the standard formula for effective slip leads to significant deviations from the behavior seen in our simulations. Self-similar decay over several orders of magnitude of the film thickness near the rupture point is observed. We also show that the presence of the grooves can lead to instability in otherwise stable films if the relative groove width is above a critical value, found as a function of disjoining pressure parameters.

  16. Structural study of Ge/GaAs thin films

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  17. Ultrahighly Dispersed Titanium Oxide on Silica : Effect of Precursors on the Structure and Photocatalysis

    OpenAIRE

    Yoshida , S.; Takenaka , S.; Tanaka , T.; Funabiki , T.

    1997-01-01

    The effect of precursor on the dispersion and catalytic performance of titanium oxide supported on silica has ben investigated. The catalysts were prepared by a simple impregnation method with three kinds of titanium complexes of different ligands (bis(isopropyato)-bis(pivaroylmethanato) : DPM, acetylacetonato : ACAC, tetrakis(isopropylato) : IPRO) with the aim of preparing ultrahighly dispersed titanium oxide on silica. The XAFS study revealed that titanium species in the catalyst prepared f...

  18. Interaction of lysozyme protein with different sized silica nanoparticles and their resultant structures

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Indresh, E-mail: iykumarindresh288@gmail.com; Aswal, V. K. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kohlbrecher, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 PSI Villigen (Switzerland)

    2016-05-23

    The interaction of model protein-lysozyme with three different sized anionic silica nanoparticles has been studied by UV-vis spectroscopy, dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The surface area and curvature of the nanoparticles change with size, which significantly influence their interaction with protein. The lysozyme adsorbs on the surface of the nanoparticles due to electrostatic attraction and leads to the phase transformation from one phase (clear) to two-phase (turbid) of the nanoparticle-protein system. The dominance of lysozyme induced short-range attraction over long-range electrostatic repulsion between nanoparticles is responsible for phase transformation and modeled by the two-Yukawa potential. The magnitude of the attractive interaction increases with the size of the nanoparticles as a result the phase transformation commences relatively at lower concentration of lysozyme. The structure of the nanoparticle-protein system in two-phase is characterized by the diffusion limited aggregate type of mass fractal morphology.

  19. Iron doped fibrous-structured silica nanospheres as efficient catalyst for catalytic ozonation of sulfamethazine.

    Science.gov (United States)

    Bai, Zhiyong; Wang, Jianlong; Yang, Qi

    2018-04-01

    Sulfonamide antibiotics are ubiquitous pollutants in aquatic environments due to their large production and extensive application. In this paper, the iron doped fibrous-structured silica (KCC-1) nanospheres (Fe-KCC-1) was prepared, characterized, and applied as a catalyst for catalytic ozonation of sulfamethazine (SMT). The effects of ozone dosage, catalyst dosage, and initial concentration of SMT were examined. The experimental results showed that Fe-KCC-1 had large surface area (464.56 m2 g -1 ) and iron particles were well dispersed on the catalyst. The catalyst had high catalytic performance especially for the mineralization of SMT, with mineralization ratio of about 40% in a wide pH range. With addition of Fe-KCC-1, the ozone utilization increased nearly two times than single ozonation. The enhancement of SMT degradation was mainly due to the surface reaction, and the increased mineralization of SMT was due to radical mechanism. Fe-KCC-1 was an efficient catalyst for SMT degradation in catalytic ozonation system.

  20. Effects of confinement in meso-porous silica and carbon nano-structures

    International Nuclear Information System (INIS)

    Leon, V.

    2006-07-01

    Physico-chemical properties of materials can be strongly modified by confinement because of the quantum effects that appear at such small length scales and also because of the effects of the confinement itself. The aim of this thesis is to show that both the nature of the confining material and the size of the pores and cavities have a strong impact on the confined material. We first show the effect of the pore size of the host meso-porous silica on the temperature of the solid-solid phase transition of silver selenide, a semiconducting material with enhanced magnetoresistive properties under non-stoichiometric conditions. Narrowing the pores from 20 nm to 2 nm raises the phase transition temperature from 139 C to 146 C. This result can be explained by considering the interaction between the confining and confined materials as a driving force. The effects of confinement are also studied in the case of hydrogen and deuterium inside cavities of organized carbon nano-structures. The effects that appear in the adsorption/desorption cycles are much stronger with carbon nano-horns as the host material than with C60 pea-pods and single-walled carbon nano-tubes. (author)

  1. Femtosecond laser-induced structural difference in fused silica with a non-reciprocal writing process

    Science.gov (United States)

    Song, Hui; Dai, Ye; Song, Juan; Ma, Hongliang; Yan, Xiaona; Ma, Guohong

    2017-04-01

    In this paper, we report a non-reciprocal writing process for inducing asymmetric microstructure using a femtosecond laser with tilted pulse fronts in fused silica. The shape of the induced microstructure at the focus closely depends on the laser scan direction. An elongated end is observed as a kind of structural difference between the written lines with two reverse scans along + x and - x, which further leads to a birefringence intensity difference. We also find a bifurcation in the head region of the induced microstructure between the written lines along x and y. That process results from the focal intensity distortion caused by the pulse front tilt by comparing the simulated intensity distribution with the experimental results. The current results demonstrate that the pulse front tilt not only affects the free electron excitation at the focus but also further distorts the shape of the induced microstructure during a high-energy femtosecond laser irradiation. These results offer a route to fabricate optical elements by changing the spatiotemporal characteristics of ultrashort pulses.

  2. The structural heterogeneity and optical properties in chalcogenide glass films

    International Nuclear Information System (INIS)

    Shurgalin, Max; Fuflyigin, Vladimir N; Anderson, Emilia G

    2005-01-01

    The microscopic structure and optical properties of glassy films prepared by vapour phase deposition process from the germanium-arsenic-selenium family of chalcogenide glasses have been studied. A number of different molecular clusters or domains that can exist in the glass structure are found to play a significant role in determining the absorption characteristics and refractive index of the glass films. Modifications of the glass structure can be described by a variation of relative concentrations of the clusters and can be effected by modifications of film chemical composition and deposition conditions. Changes in absorption spectra are directly correlated with variation in relative concentrations of the structural fragments with different electronic bandgap properties. Experimental results suggest structural heterogeneity and support validity of the cluster structural model for the chalcogenide glasses

  3. Structures and Elastic Moduli of Polymer Nanocomposite Thin Films

    Science.gov (United States)

    Yuan, Hongyi; Karim, Alamgir; University of Akron Team

    2014-03-01

    Polymeric thin films generally possess unique mechanical and thermal properties due to confinement. In this study we investigated structures and elastic moduli of polymer nanocomposite thin films, which can potentially find wide applications in diverse areas such as in coating, permeation and separation. Conventional thermoplastics (PS, PMMA) and biopolymers (PLA, PCL) were chosen as polymer matrices. Various types of nanoparticles were used including nanoclay, fullerene and functionalized inorganic particles. Samples were prepared by solvent-mixing followed by spin-coating or flow-coating. Film structures were characterized using X-ray scattering and transmission electron microscopy. Elastic moduli were measured by strain-induced elastic buckling instability for mechanical measurements (SIEBIMM), and a strengthening effect was found in certain systems due to strong interaction between polymers and nanoparticles. The effects of polymer structure, nanoparticle addition and film thickness on elastic modulus will be discussed and compared with bulk materials.

  4. Structures of sub-monolayered silicon carbide films

    International Nuclear Information System (INIS)

    Baba, Y.; Sekiguchi, T.; Shimoyama, I.; Nath, Krishna G.

    2004-01-01

    The electronic and geometrical structures of silicon carbide thin films are presented. The films were deposited on graphite by ion-beam deposition using tetramethylsilane (TMS) as an ion source. In the Si K-edge near-edge X-ray absorption fine structure (NEXAFS) spectra for sub-monolayered film, sharp peaks due to the resonance from Si 1s to π*-like orbitals were observed, suggesting the existence of Si=C double bonds. On the basis of the polarization dependencies of the Si 1s → π* peak intensities, it is elucidated that the direction of the π*-like orbitals is just perpendicular to the surface. We conclude that the sub-monolayered SiC x film has a flat-lying hexagonal structure of which configuration is analogous to the single sheet of graphite

  5. Chain and mirophase-separated structures of ultrathin polyurethane films

    International Nuclear Information System (INIS)

    Kojio, Ken; Yamamoto, Yasunori; Motokucho, Suguru; Furukawa, Mutsuhisa; Uchiba, Yusuke

    2009-01-01

    Measurements are presented how chain and microphase-separated structures of ultrathin polyurethane (PU) films are controlled by the thickness. The film thickness is varied by a solution concentration for spin coating. The systems are PUs prepared from commercial raw materials. Fourier-transform infrared spectroscopic measurement revealed that the degree of hydrogen bonding among hard segment chains decreased and increased with decreasing film thickness for strong and weak microphase separation systems, respectively. The microphase-separated structure, which is formed from hard segment domains and a surrounding soft segment matrix, were observed by atomic force microscopy. The size of hard segment domains decreased with decreasing film thickness, and possibility of specific orientation of the hard segment chains was exhibited for both systems. These results are due to decreasing space for the formation of the microphase-separated structure.

  6. Characterization of electron beam deposited thin films of HfO2 and binary thin films of (HfO2:SiO2) by XRD and EXAFS measurements

    International Nuclear Information System (INIS)

    Das, N.C.; Sahoo, N.K.; Bhattacharyya, D.; Thakur, S.; Kamble, N.M.; Nanda, D.; Hazra, S.; Bal, J.K.; Lee, J.F.; Tai, Y.L.; Hsieh, C.A.

    2009-10-01

    In this report, we have discussed the microstructure and the local structure of composite thin films having varying hafnia and silica compositions and prepared by reactive electron beam evaporation. XRD and EXAFS studies have confirmed that the pure hafnium oxide thin film has crystalline microstructure whereas the films with finite hafnia and silica composition are amorphous. The result of EXAFS analysis has shown that the bond lengths as well as coordination numbers around hafnium atom change with the variation of hafnia and silica compositions in the thin film. Finally, change of bond lengths has been correlated with change of refractive index and band gap of the composite thin films. (author)

  7. Structural morphology of amorphous conducting carbon film

    Indian Academy of Sciences (India)

    Unknown

    moves from low preparation temperature to high preparation temperature. The amorphous .... nm and the interac- tion between the pi-electron clouds of the two layers re- .... sp2 configuration forms to minimize stress and making. C900 films ...

  8. An improved model for estimating fractal structure of silica nano-agglomerates in a vibro-fluidized bed

    OpenAIRE

    A Esmailpour; N Mostoufi; R Zarghami

    2016-01-01

    A study has been conducted to determine the effects of operating conditions such as vibration frequency, vibration amplitude on the fractal structure of silica (SiO2) nanoparticle agglomerate in a vibro-fluidized bed. An improved model was proposed by assimilation of fractal theory, Richardson-Zaki equation and mass balance. This model has been developed to predict the properties of nanoparticle agglomerate, such as fractal dimension and its size. It has been found out the vibration intensity...

  9. Influence of structure of carrier (silica gel) on texture and catalytic properties of vanadium catalysts for sulfur dioxide oxidation

    International Nuclear Information System (INIS)

    Simonova, L.G.; Fenelonov, V.B.; Dzis'ko, V.A.; Noskova, S.P.; Kryukova, G.N.; Litvak, G.S.

    1982-01-01

    The influence of initial porous structure of a carrier-silica gel on texture and catalytic properties of vanadium catalysts is considered. It is shown that low thermal stability of the carrier results not only in considerable decrease of the catalyst surface during heat treatment but also in blocking part of active component in locked pores which accounts for the activity decrease in kinetic region and formation of active component forms that can not be extracted by acid

  10. Constructing a Multiple Covalent Interface and Isolating a Dispersed Structure in Silica/Rubber Nanocomposites with Excellent Dynamic Performance.

    Science.gov (United States)

    Zheng, Junchi; Han, Dongli; Zhao, Suhe; Ye, Xin; Wang, Yiqing; Wu, Youping; Dong, Dong; Liu, Jun; Wu, Xiaohui; Zhang, Liqun

    2018-06-13

    Realizing and manipulating a fine dispersion of silica nanoparticles (NPs) in the polymer matrix is always a great challenge. In this work, we first successfully synthesized N, N'-bis[3-(triethoxysilyl)propyl-isopropanol]-propane-1,3-diamine (TSPD), which was a new interface modifier, aiming to promote the dispersion of silica NPs. Through Fourier transform infrared spectroscopy, nuclear magnetic resonance analysis, and mass spectroscopy, we verified that TSPD contains together six ethoxy groups at its two ends. Then, we used this TSPD to modify the pure silica NPs, and this modified silica was abbreviated as D-MS, which is realized by the thermal gravimetric analysis examination, scanning electron microscopy analysis, and dynamic light scattering results. It was clearly observed that D-MS NPs are connected to one another but are not conglutinated tightly, exhibiting a novel predispersed structure with around 1-2 nm certain extent of interparticle distance. Next, we fabricated the following four elastomer nanocomposites such as pure silica/natural rubber (NR) composite (PS-NR), D-MS/NR composite (DMS-NR), bis-(γ-triethoxysilylpropyl)-tetrasulfide (TESPT)-modified silica/NR composite (TS-NR), and TESPT-modified D-MS/NR composite (T&DMS-NR) and found that the Payne effect is the smallest for T&DMS-NR via the combination use of the D-MS and the traditional coupling agent TESPT, which is attributed to its best dispersion state evidenced by the transmission electron microscopy results. Moreover, by measuring a series of other important mechanical performances such as the stress-strain curve, the dynamic strain dependence of the loss factor, and the heat build-up, we concluded that the T&DMS-NR system greatly exceeds those of the three other rubber composites. In general, this new approach provides a good opportunity to prepare a silica/rubber composite with excellent properties in mechanical strength and dynamic behavior by tailoring the fine dispersion of NPs.

  11. Structural characterization of casein micelles: shape changes during film formation

    International Nuclear Information System (INIS)

    Gebhardt, R; Kulozik, U; Vendrely, C

    2011-01-01

    The objective of this study was to determine the effect of size-fractionation by centrifugation on the film structure of casein micelles. Fractionated casein micelles in solution were asymmetrically distributed with a small distribution width as measured by dynamic light scattering. Films prepared from the size-fractionated samples showed a smooth surface in optical microscopy images and a homogeneous microstructure in atomic force micrographs. The nano- and microstructure of casein films was probed by micro-beam grazing incidence small angle x-ray scattering (μGISAXS). Compared to the solution measurements, the sizes determined in the film were larger and broadly distributed. The measured GISAXS patterns clearly deviate from those simulated for a sphere and suggest a deformation of the casein micelles in the film. (paper)

  12. Structural changes in irreversibly densified fused silica: implications for the chemical resistance of high level nuclear waste glasses

    International Nuclear Information System (INIS)

    Susman, S.; Volin, K.J.; Liebermann, R.C.; Gwanmesia, G.D.; Yanbin Wang

    1990-01-01

    Energetic photons and energetic particles create changes in the structure of nuclear waste glasses. These can be observed as changes in the average bulk physical properties. For example, exposure of fused silica to high doses of neutron bombardment leads to a maximum average compaction of 3%. However, this does not reveal the true extent of the densification that takes place at a microscopic level. Recent advances in high pressure technology have yielded large samples of fused silica which have been permanently densified under pressure and whose bulk density has been increased by 20%. These specimens have an overall structure that replicates the microstructure of a radiation damaged glass. Measurements have been made for the first time of the structural changes in this pressure densified vitreous silica using neutron diffraction and infrared absorption spectrometry. Extensive alterations in intermediate range order have been observed with consequent anticipated changes in chemical reactivity. The resistance of high level waste glasses to leaching by groundwater must be considered in light of these experimental findings. (author)

  13. Reactive wetting of amorphous silica by molten Al–Mg alloys and their interfacial structures

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Laixin [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Shen, Ping, E-mail: shenping@jlu.edu.cn [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); Zhang, Dan [Editorial Office, Journal of Bionic Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); Jiang, Qichuan [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China)

    2016-07-30

    Highlights: • The wettability improves with increasing Mg concentration and temperature. • Reaction product zone consists of layered structures relating with Mg concentration. • Formation of MgAl{sub 2}O{sub 4} and MgO at the interface does not promote the wettability. • Formation of Mg{sub 2}Si plays a dominant role in promoting the wettability. • Anomalous recession of the triple line was mainly due to diminishing Mg in the alloy. - Abstract: The reactive wetting of amorphous silica substrates by molten Al–Mg alloys over a wide composition range was studied using a dispensed sessile drop method in a flowing Ar atmosphere. The effects of the nominal Mg concentration and temperature on the wetting and interfacial microstructures were discussed. The initial contact angle for pure Al on the SiO{sub 2} surface was 115° while that for pure Mg was 35° at 1073 K. For the Al–Mg alloy drop, it decreased with increasing nominal Mg concentration. The reaction zone was characterized by layered structures, whose formation was primarily controlled by the variation in the alloy concentration due to the evaporation of Mg and the interfacial reaction from the viewpoint of thermodynamics as well as by the penetration or diffusion of Mg, Al and Si from the viewpoint of kinetics. In addition, the effects of the reaction and the evaporation of Mg on the movement of the triple line were examined. The spreading of the Al–Mg alloy on the SiO{sub 2} surface was mainly attributed to the formation of Mg{sub 2}Si at the interface and the recession of the triple line to the diminishing Mg concentration in the alloy.

  14. Structures and properties of fluorinated amorphous carbon films

    Science.gov (United States)

    Huang, K. P.; Lin, P.; Shih, H. C.

    2004-07-01

    Fluorinated amorphous carbon (a-C:F) films were deposited by radio frequency bias assisted microwave plasma electron cyclotron resonance chemical vapor deposition with tetrafluoromethane (CF4) and acetylene (C2H2) as precursors. The deposition process was performed at two flow ratios R=0.90 and R=0.97, where R=CF4/(CF4+C2H2). The samples were annealed at 300 °C for 30 min. in a N2 atmosphere. Both Fourier transform infrared and electron spectroscopy for chemical analyzer were used to characterize the a-C:F film chemical bond and fluorine concentration, respectively. A high resolution electron energy loss spectrometer was applied to detect the electronic structure. The higher CF4 flow ratio (R=0.97) produced more sp3 linear structure, and it made the a-C:F film smoother and softer. A lifetime of around 0.34 μs and an energy gap of ˜2.75 eV were observed in both the as-deposited and after annealing conditions. The short carriers lifetime in the a-C:F film made the photoluminescence peak blueshift. The annealing changed both the structure and composition of the a-C:F film. The type of fluorocarbon bond and electronic structure characterized the mechanical and physical properties of a-C:F film.

  15. Preparation of Ferroelectric Thin Films of Bismuth Layer Structured Compounds

    Science.gov (United States)

    Watanabe, Hitoshi; Mihara, Takashi; Yoshimori, Hiroyuki; Araujo, Carlos

    1995-09-01

    Ferroelectric thin films of bismuth layer structured compounds, SrBi2Ta2O9, SrBi2Nb2O9, SrBi4Ti4O15 and their solid solutions, were formed onto a sputtered platinum layer on a silicon substrate using spin-on technique and metal-organic decomposition (MOD) method. X-ray diffraction (XRD) analysis and some electrical measurements were performed on the prepared thin films. XRD results of SrBi2(Ta1- x, Nb x)2O9 films (0≤x≤1) showed that niobium ions substitute for tantalum ions in an arbitrary ratio without any change of the layer structure and lattice constants. Furthermore, XRD results of SrBi2 xTa2O9 films (0≤x≤1.5) indicated that the formation of the bismuth layer structure does not always require an accurate bismuth content. The layer structure was formed above 50% of the stoichiometric bismuth content in the general formula. SrBi2(Ta1- x, Nb x)2O9 films with various Ta/Nb ratios have large enough remanent polarization for nonvolatile memory application and have shown high fatigue resistance against 1011 cycles of full switching of the remanent polarization. Mixture films of the three compounds were also investigated.

  16. Liquid Phase Deposition of Silica on the Hexagonally Close-Packed Monolayer of Silica Spheres

    Directory of Open Access Journals (Sweden)

    Seo Young Yoon

    2013-01-01

    Full Text Available Liquid phase deposition is a method used for the nonelectrochemical production of polycrystalline ceramic films at low temperatures, most commonly silicon dioxide films. Herein, we report that silica spheres are organized in a hexagonal close-packed array using a patterned substrate. On this monolayer of silica spheres, we could fabricate new nanostructures in which deposition and etching compete through a modified LPD reaction. In the early stage, silica spheres began to undergo etching, and then, silica bridges between the silica spheres appeared by the local deposition reaction. Finally, the silica spheres and bridges disappeared completely. We propose the mechanism for the formation of nanostructure.

  17. Thin NbN film structures on SOI for SNSPD

    Energy Technology Data Exchange (ETDEWEB)

    Il' in, Konstantin; Kurz, Stephan; Henrich, Dagmar; Hofherr, Matthias; Siegel, Michael [IMS, KIT, Karlsruhe (Germany); Semenov, Alexei; Huebers, Heinz-Wilhelm [DLR, Berlin (Germany)

    2012-07-01

    Superconducting Nanowire Single-Photon Detectors (SNSPD) made from ultra-thin NbN films on sapphire demonstrate almost 100% intrinsic detection efficiency (DE). However the system DE values is less than 10% mostly limited by a very low absorptance of NbN films thinner than 5 nm. Integration of SNSPD in Si photonic circuit is a promising way to overcome this problem. We present results on optimization of technology of thin NbN film nanostructures on SOI (Silicon on Insulator) substrate used in Si photonics technology. Superconducting and normal state properties of these structures important for SNSPD development are presented and discussed.

  18. The structural and optical characterizations of tetraphenylporphyrin thin films

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf, M.M., E-mail: m_makhlof@hotmail.com [Physics Department, Faculty of Applied Medical Science at Turabah branch, Taif University, Turabah, 21995 (Saudi Arabia); Department of Physics, Faculty of Science at New Damietta, Damietta University, New Damietta 34517 (Egypt); El-Denglawey, A. [Physics Department, Faculty of Applied Medical Science at Turabah branch, Taif University, Turabah, 21995 (Saudi Arabia); Physics Department, Faculty of Science, South Valley University, Qena 83523 (Egypt); Zeyada, H.M. [Department of Physics, Faculty of Science at New Damietta, Damietta University, New Damietta 34517 (Egypt); El-Nahass, M.M. [Physics Department, Faculty of Education, Ain Shams University, Cairo (Egypt)

    2014-03-15

    X-rays diffraction and scanning electron microscope were used to investigate the structural properties of tetraphenylporphyrin, TPP, which is polycrystalline in a synthesized condition. It turns to amorphous structure upon thermal deposition. Annealing temperature ranging from 295 to 473 K does not influence the amorphous structure of films. The optical properties of TPP were investigated using spectrophotometric measurements of the transmittance and reflectance at normal incidence in the wavelength range of 200–2200 nm. The absorption spectra were recorded in UV–visible region of spectra for the as-deposited and annealed samples show different absorption bands, namely four bands labeled as Q-band in visible region of spectra and a more intense band termed as the Soret band in near UV region of spectra. The Soret band shows its splitting (Davydov splitting). Two other bands labeled N and M appear in UV region. The film thickness has no influence on optical properties of films while annealing temperatures have a slight influence on optical properties of TPP films. The type of optical transition in as deposited and annealed conditions of films was found to be indirect allowed band-gap. Both fundamental and onset energy gap decreases upon annealing. -- Highlights: • Tetraphenylporphyrin (TPP) is polycrystalline in powder form, while the as-deposited and annealed TPP thin films have amorphous structure. • The absorption spectra of TPP in UV–visible region consists of Q-bands, Soret band and two other bands labeled N and M. • The optical parameters of TPP thin film were measured. • Thermal annealing influences optical properties of TPP thin films.

  19. Study of the structure of polyethyleneterphtalate (PET) films

    International Nuclear Information System (INIS)

    Melinte, S.; Leanca, M.; Moise, M.; Mateescu, N.

    1979-01-01

    In the process of polymer stretching, there occur structural modifications (detected by X-ray diffraction) which are reflected in the superstructure, as revealed by electron microscopy. The paper studies three types of polyethyleneterphtalate films, taken from the stages of the technological process of obtention of two-way stretched films: extruded ones, one-way stretched ones and two-way stretched ones. (author)

  20. The structural and optical characterizations of tetraphenylporphyrin thin films

    International Nuclear Information System (INIS)

    Makhlouf, M.M.; El-Denglawey, A.; Zeyada, H.M.; El-Nahass, M.M.

    2014-01-01

    X-rays diffraction and scanning electron microscope were used to investigate the structural properties of tetraphenylporphyrin, TPP, which is polycrystalline in a synthesized condition. It turns to amorphous structure upon thermal deposition. Annealing temperature ranging from 295 to 473 K does not influence the amorphous structure of films. The optical properties of TPP were investigated using spectrophotometric measurements of the transmittance and reflectance at normal incidence in the wavelength range of 200–2200 nm. The absorption spectra were recorded in UV–visible region of spectra for the as-deposited and annealed samples show different absorption bands, namely four bands labeled as Q-band in visible region of spectra and a more intense band termed as the Soret band in near UV region of spectra. The Soret band shows its splitting (Davydov splitting). Two other bands labeled N and M appear in UV region. The film thickness has no influence on optical properties of films while annealing temperatures have a slight influence on optical properties of TPP films. The type of optical transition in as deposited and annealed conditions of films was found to be indirect allowed band-gap. Both fundamental and onset energy gap decreases upon annealing. -- Highlights: • Tetraphenylporphyrin (TPP) is polycrystalline in powder form, while the as-deposited and annealed TPP thin films have amorphous structure. • The absorption spectra of TPP in UV–visible region consists of Q-bands, Soret band and two other bands labeled N and M. • The optical parameters of TPP thin film were measured. • Thermal annealing influences optical properties of TPP thin films

  1. Two-step excitation structure changes of luminescence centers and strong tunable blue emission on surface of silica nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lei, E-mail: nanoyang@qq.com; Jiang, Zhongcheng; Dong, Jiazhang; Zhang, Liuqian [Hunan University, College of Materials Science and Engineering (China); Pan, Anlian, E-mail: anlian.pan@gmail.com; Zhuang, Xiujuan [Hunan University, Key Laboratory for Micro-Nano Physics and Technology of Hunan Province (China)

    2015-10-15

    We report a scheme for investigating two-step stimulated structure change of luminescence centers. Amorphous silica nanospheres with uniform diameter of 9–15 nm have been synthesized by Stöber method. Strong hydroxyl-related infrared-absorption band is observed in infrared spectrum. The surface hydroxyl groups exert great influence on the luminescent behavior of silica. They provide stable and intermediate energy states to accommodate excitation electrons. The existence of these surface states reduces the energy barrier of photochemical reactions, creating conditions for two-step excitation process. By carefully examining excitation and emission process, the nearest excitation band is absent in both optical absorption spectrum and excitation spectrum. This later generated state confirms the generation of new luminescence centers as well as the existence of photochemical reactions. Stimulated by different energies, two-step excitation process impels different photochemical reactions, prompting generation of different lattice defects on surface area of silica. Thereby, tunable luminescence is achieved. After thermal treatment, strong gap excitation band appears with the disappearance of strong surface excitation band. Strong blue luminescence also disappears. The research is significance to precise introducing structural defects and controlling position of luminescence peaks.

  2. Structure and properties of diamond and diamond-like films

    Energy Technology Data Exchange (ETDEWEB)

    Clausing, R.E. [Oak Ridge National Lab., TN (United States)

    1993-01-01

    This section is broken into four parts: (1) introduction, (2) natural IIa diamond, (3) importance of structure and composition, and (4) control of structure and properties. Conclusions of this discussion are that properties of chemical vapor deposited diamond films can compare favorably with natural diamond, that properties are anisotropic and are a strong function of structure and crystal perfection, that crystal perfection and morphology are functions of growth conditions and can be controlled, and that the manipulation of texture and thereby surface morphology and internal crystal perfection is an important step in optimizing chemically deposited diamond films for applications.

  3. [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.

  4. SANS study of interaction of silica nanoparticles with BSA protein and their resultant structure

    International Nuclear Information System (INIS)

    Yadav, Indresh; Aswal, V. K.; Kohlbrecher, J.

    2014-01-01

    Small angle neutron scattering (SANS) has been carried out to study the interaction of anionic silica nanoparticles (88 Å) with globular protein Bovine Serum Albumin (BSA) (M.W. 66.4 kD) in aqueous solution. The measurements have been carried out on fixed concentration (1 wt %) of Ludox silica nanoparticles with varying concentration of BSA (0–5 wt %) at pH7. Results show that silica nanoparticles and BSA coexist as individual entities at low concentration of BSA where electrostatic repulsive interactions between them prevent their aggregation. However, as the concentration of BSA increases (≥ 0.5 wt %), it induces the attractive depletion interaction among nanoparticles leading to finally their aggregation at higher BSA concentration (2 wt %). The aggregates are found to be governed by the diffusion limited aggregation (DLA) morphology of fractal nature having fractal dimension about 2.4

  5. Dimensional and Structural Control of Silica Aerogel Membranes for Miniaturized Motionless Gas Pumps.

    Science.gov (United States)

    Zhao, Shanyu; Jiang, Bo; Maeder, Thomas; Muralt, Paul; Kim, Nayoung; Matam, Santhosh Kumar; Jeong, Eunho; Han, Yen-Lin; Koebel, Matthias M

    2015-08-26

    With growing public interest in portable electronics such as micro fuel cells, micro gas total analysis systems, and portable medical devices, the need for miniaturized air pumps with minimal electrical power consumption is on the rise. Thus, the development and downsizing of next-generation thermal transpiration gas pumps has been investigated intensively during the last decades. Such a system relies on a mesoporous membrane that generates a thermomolecular pressure gradient under the action of an applied temperature bias. However, the development of highly miniaturized active membrane materials with tailored porosity and optimized pumping performance remains a major challenge. Here we report a systematic study on the manufacturing of aerogel membranes using an optimized, minimal-shrinkage sol-gel process, leading to low thermal conductivity and high air conductance. This combination of properties results in superior performance for miniaturized thermomolecular air pump applications. The engineering of such aerogel membranes, which implies pore structure control and chemical surface modification, requires both chemical processing know-how and a detailed understanding of the influence of the material properties on the spatial flow rate density. Optimal pumping performance was found for devices with integrated membranes with a density of 0.062 g cm(-3) and an average pore size of 142.0 nm. Benchmarking of such low-density hydrophobic active aerogel membranes gave an air flow rate density of 3.85 sccm·cm(-2) at an operating temperature of 400 °C. Such a silica aerogel membrane based system has shown more than 50% higher pumping performance when compared to conventional transpiration pump membrane materials as well as the ability to withstand higher operating temperatures (up to 440 °C). This study highlights new perspectives for the development of miniaturized thermal transpiration air pumps while offering insights into the fundamentals of molecular pumping in

  6. Response to Extreme Temperatures of Mesoporous Silica MCM-41: Porous Structure Transformation Simulation and Modification of Gas Adsorption Properties.

    Science.gov (United States)

    Zhang, Shenli; Perez-Page, Maria; Guan, Kelly; Yu, Erick; Tringe, Joseph; Castro, Ricardo H R; Faller, Roland; Stroeve, Pieter

    2016-11-08

    Molecular dynamics (MD) and Monte Carlo (MC) simulations were applied together for the first time to reveal the porous structure transformation mechanisms of mesoporous silica MCM-41 subjected to temperatures up to 2885 K. Silica was experimentally characterized to inform the models and enable prediction of changes in gas adsorption/separation properties. MD simulations suggest that the pore closure process is activated by a collective diffusion of matrix atoms into the porous region, accompanied by bond reformation at the surface. Degradation is kinetically limited, such that complete pore closure is postponed at high heating rates. We experimentally observe decreased gas adsorption with increasing temperature in mesoporous silica heated at fixed rates, due to pore closure and structural degradation consistent with simulation predictions. Applying the Kissinger equation, we find a strong correlation between the simulated pore collapse temperatures and the experimental values which implies an activation energy of 416 ± 17 kJ/mol for pore closure. MC simulations give the adsorption and selectivity for thermally treated MCM-41, for N 2 , Ar, Kr, and Xe at room temperature within the 1-10 000 kPa pressure range. Relative to pristine MCM-41, we observe that increased surface roughness due to decreasing pore size amplifies the difference of the absolute adsorption amount differently for different adsorbate molecules. In particular, we find that adsorption of strongly interacting molecules can be enhanced in the low-pressure region while adsorption of weakly interacting molecules is inhibited. This then results in higher selectivity in binary mixture adsorption in mesoporous silica.

  7. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.

    2004-01-01

    The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order...

  8. Corundum ceramic materials modified with silica nanopowders: structure and mechanical properties

    International Nuclear Information System (INIS)

    Kostytsyn, M. A.; Muratov, D. S.; Lysov, D. V.; Chuprunov, K. O.; Yudin, A. G.; Leybo, D. V.

    2016-01-01

    Filtering elements are often used in the metallurgy of rare earth metals. Corundum ceramic is one of the most suitable materials for this purpose. The process of formation and the properties of nanomodified ceramic materials, which are proposed as filtering materials with tunable effective porosity, are described. A silica nanopowder is used as a porosity-increasing agent. Vortex layer apparatus is used for mixing of precursor materials. The obtained results show that nanomodification with the vortex layer apparatus using 0.04 wt. % silica nanopowder as a modifying agent leads to an increase in the compression strength of corundum ceramic by the factor of 1.5. (paper)

  9. SEM and Raman studies of CNT films on porous Si

    Science.gov (United States)

    Belka, R.; Keczkowska, J.; Suchańska, M.; Firek, P.; Wronka, H.; Kozłowski, M.; Radomska, J.; Czerwosz, E.; Craciunoiu, F.

    2017-08-01

    Carbon nanotube (CNT) films deposited on different porous silica substrates were studied by Scanning Electron Microscopy (SEM) and Raman Spectroscopy (RS). The films samples were prepared by a two-step method consisting of PVD and CVD processes. In the first step the nanocomposite Ni-C film was obtained by evaporation in dynamic vacuum from two separated sources of fullerenes and nickel acetate. Those films were deposited on porous silica and DLC/porous silica substrates. Analysis of SEM imaging showed that the obtained film are composed of carbon nanotubes, the distribution, size and quality of which depend on the type of substrate. The CNT films were studied by RS method to determine the influence of the substrate type on disordering of carbonaceous structure and quality of CNT in deposited films.

  10. Improving structural stability of water-dispersed MCM-41 silica nanoparticles through post-synthesis pH aging process

    Energy Technology Data Exchange (ETDEWEB)

    Varache, Mathieu; Bezverkhyy, Igor [UMR 6303 CNRS-Université Bourgogne Franche-Comté, Laboratoire Interdisciplinaire Carnot de Bourgogne (France); Bouyer, Florence [Inserm U866, Equipe Chimiothérapie, métabolisme des lipides et réponse immunitaire anti-tumorale (France); Chassagnon, Rémi; Baras, Florence; Bouyer, Frédéric, E-mail: frederic.bouyer@u-bourgogne.fr [UMR 6303 CNRS-Université Bourgogne Franche-Comté, Laboratoire Interdisciplinaire Carnot de Bourgogne (France)

    2015-09-15

    The colloidal and structural stabilities of MCM-41 mesoporous silica nanoparticles (MSNs) are of great importance in order to prepare optimal nanovectors. In this paper, MSNs (approximatively 160 nm in diameter) were synthesized using n-cetyltrimethylammonium bromide as a template and tetraethyl orthosilicate as a silica source under high N{sub 2} flow (MSN/N{sub 2}) to obtain stable dispersions in water. The degradation of the porous nanoparticles was investigated by immersion in water. The morphology and the porous structure were studied by TEM, XRD, N{sub 2} sorption, and {sup 29}Si MAS NMR and were compared to that of MSNs prepared in ambient air (MSN/air). The volumetric properties of the MSN/N{sub 2} after 1 day in water were drastically more decreased than MSN/air (a pore volume decrease of 85 % for MSN/N{sub 2} and 59 % for MSN/air) and the 2D-hexagonal porous structure was totally lost. Furthermore, synthesizing MSNs under a high N{sub 2} flow leads to a decrease in the synthesis yield (45 % MSN/N{sub 2} and 75 % for MSN/air). The lower structural stability of the MSN/N{sub 2} is explained by the lower polycondensation degree of the MSN/N{sub 2} observed by {sup 29}Si MAS NMR (Q{sup 4}/Q{sup 3} = 0.86 for MSN/N{sub 2} and 1.61 for MSN/air) and the lower silica molar ratio in the nanomaterials (SiO{sub 2}/CTA = 3.9 for MSN/N{sub 2} 7.1 for MSN/air). This allows for enhanced solubilization of silica in water. Four strategies were hence evaluated in order to reinforce the porous structure of the MSNs. Among them, the most efficient route was based on a pH adjustment of the colloidal suspension (pH 7.5) after 2 h of synthesis without any purification and while keeping a N{sub 2} static atmosphere (called MSN/N{sub 2}/7.5). After 1 day in water, the volumetric and structural properties of MSN/N{sub 2}/7.5 were similar to that obtained for MSN/air. The improvement of the stability arose as a result of the increase in the silica condensation (Q{sup 4

  11. Simultaneous measurements of top surface and its underlying film surfaces in multilayer film structure.

    Science.gov (United States)

    Ghim, Young-Sik; Rhee, Hyug-Gyo; Davies, Angela

    2017-09-19

    With the growth of 3D packaging technology and the development of flexible, transparent electrodes, the use of multilayer thin-films is steadily increasing throughout high-tech industries including semiconductor, flat panel display, and solar photovoltaic industries. Also, this in turn leads to an increase in industrial demands for inspection of internal analysis. However, there still remain many technical limitations to overcome for measurement of the internal structure of the specimen without damage. In this paper, we propose an innovative optical inspection technique for simultaneous measurements of the surface and film thickness corresponding to each layer of multilayer film structures by computing the phase and reflectance over a wide range of wavelengths. For verification of our proposed method, the sample specimen of multilayer films was fabricated via photolithography process, and the surface profile and film thickness of each layer were measured by two different techniques of a stylus profilometer and an ellipsometer, respectively. Comparison results shows that our proposed technique enables simultaneous measurements of the top surface and its underlying film surfaces with high precision, which could not be measured by conventional non-destructive methods.

  12. Crystal structures of sol-gel deposited zirconia thin films

    International Nuclear Information System (INIS)

    Bell, J.M.; Cheary, R.W.; Rice, M.; Ben-Nissan, B.; Cocking, J.L.; Johnstone, G.R.

    1992-01-01

    The authors reports on the crystal structure of zirconia thin films by high temperature x-ray diffraction. The films were deposited by sol-gel processing onto polished stainless steel substrates, and dried at 200 deg C. X-ray diffraction at temperatures between 400 deg C and 800 deg C was carried out using an APEX diffractometer with a position sensitive detector. Previous results indicated that there was a transformation between the tetragonal phase and the monoclinic phase at approximately 770 deg C. Two experiments have been carried out: temperature runs, where the structure evolution is studied as a function of temperature; and time evolution of the structure at fixed temperatures. The results for both experiments, including structural analysis of the different phases found in the thin zirconia films and an analysis of the kinetics of the phase transformation(s) from the time evolution work are presented. This will include a comparison with theories of nucleation and crystallisation in single element films. Impurity phases introduced by interaction of the zirconia with the substrate have been observed, and the effect of increasing annealing time on the substrate-film interaction will also be discussed. 17 refs., 1 tab., 3 figs

  13. Alternative nano-structured thin-film materials used as durable thermal nanoimprint lithography templates

    Science.gov (United States)

    Bossard, M.; Boussey, J.; Le Drogoff, B.; Chaker, M.

    2016-02-01

    Nanoimprint templates made of diamond-like carbon (DLC) and amorphous silicon carbide (SiC) thin films and fluorine-doped associated materials, i.e. F-DLC and F-SiC were investigated in the context of thermal nanoimprint lithography (NIL) with respect to their release properties. Their performances in terms of durability and stability were evaluated and compared to those of conventional silicon or silica molds coated with antisticking molecules applied as a self-assembled monolayer. Plasma-enhanced chemical vapor deposition parameters were firstly tuned to optimize mechanical and structural properties of the DLC and SiC thin films. The impact of the amount of fluorine dopant on the deposited thin films properties was then analyzed. A comparative analysis of DLC, F-DLC as well as SiC and F-SiC molds was then carried out over multiple imprints, performed into poly (methyl methacrylate) (PMMA) thermo-plastic resist. The release properties of un-patterned films were evaluated by the measurement of demolding energies and surface energies, associated with a systematic analysis of the mold surface contamination. These analyses showed that the developed materials behave as intrinsically easy-demolding and contamination-free molds over series of up to 40 imprints. To our knowledge, it is the first time that such a large number of imprints has been considered within an exhaustive comparative study of materials for NIL. Finally, the developed materials went through standard e-beam lithography and plasma etching processes to obtain nanoscale-patterned templates. The replicas of those patterned molds, imprinted into PMMA, were shown to be of high fidelity and good stability after several imprints.

  14. Growth-related magnetic and physical structures in CMR films

    Energy Technology Data Exchange (ETDEWEB)

    Hawley, M.E.; Brown, G.W.; Hundley, M.F. [and others

    1997-09-01

    Scanning tunneling microscopy (STM), atomic force microscopy (AFM), and magnetic force microscopy (MFM) have proven to be powerful tools for revealing property-sensitive structures in magnetic materials. With the renewed interest in perovskite films as materials for read-heads in high density magnetic data storage, the same challenges faced by high temperature superconductor (HTS) film fabrication are repeated for these materials. To begin addressing these challenges, we used vapor phase epitaxy to fabricate La (Sr, Ca,) based manganate films on single crystal perovskite substrates under different conditions and characterized them with scanning probe microscopies, x-ray diffraction, and temperature-dependent magnetization and resistivity measurements (M(T) and {rho}(T)). The as-grown films were polygranular with grain sizes increasing with increasing temperature (T). The post-deposition annealed films consisted of coalesced layers with improved transport properties. The room temperature magnetic structure of the Sr-based films appeared to be related to defects and/or strain.

  15. Assembly of crosslinked oxo-cyanoruthenate and zirconium oxide bilayers: Application in electrocatalytic films based on organically modified silica with templated pores

    International Nuclear Information System (INIS)

    Rutkowska, Iwona A.; Sek, Jakub P.; Mehdi, B. Layla; Kulesza, Pawel J.; Cox, James A.

    2014-01-01

    Electrochemical deposition of crosslinked oxo-cyanoruthenate, Ru-O/CN-O, from a mixture of RuCl 3 and K 4 Ru(CN) 6 is known to yield a film on glassy carbon that promotes oxidations by a combination of electron and oxygen transfer. Layer-by-layer (LbL) deposition of this species at a film formed by cycling of the electrode potential in a ZrO 2 solution systematically increases the number of catalytically active sites of the Ru-O/CN-O on the electrode. The evaluation of the electrocatalytic activity was by cyclic voltammetric oxidation of cysteine at pH 2. Plots of the anodic peak current vs. the square root of scan rate were indicative of linear diffusion control of this oxidation, even in the absence of ZrO 2 , but the slopes of these linear plots increased with bilayer number, n, of (ZrO 2 | Ru-O/CN-O) n . The latter observation is hypothesized to be due to an increased number of active sites for a given geometric electrode area, but proof requires further study. To optimize utilization of the catalyst and to provide a size-exclusion characteristic to the electrode, the study was extended to LbL deposition of the composite in 50-nm pores of an organically modified silica film deposited by electrochemically assisted sol-gel processing using surface-bound poly(styrene sulfonate) nanospheres as a templating agent

  16. Growth and structure of Co/Au magnetic thin films

    International Nuclear Information System (INIS)

    Marsot, N.

    1999-01-01

    We have studied the growth and the crystallographic structure of magnetic ultra thin cobalt/gold films (Co/Au), in order to investigate the correlations between their magnetic and structural properties. Room temperature (R.T.) Co growth on Au (111) proceeds in three stages. Up to 2 Co monolayers (ML), a bilayer island growth mode is observed. Between 2 and 5 ML, coalescence of the islands occurs, covering the substrate surface and a Co/Au mixing is observed resulting from the de-construction of the Herringbone reconstruction. Finally, beyond 5 ML, the CoAu mixing is buried and the Co growth continues in a 3-D growth. Annealing studies at 600 K on this system show a smoothing effect of the Co film, and at the same time, segregation of Au atoms. The quality of the Co/Au interface (sharpness) is not enhanced by the annealing. The local order was studied by SEXAFS and the long range order by GIXRD showing that the Co film has a hexagonal close packed structure, with an easy magnetization axis perpendicular to the surface. From a local order point of view, the Co grows with an incoherent epitaxy and keeps its own bulk parameters. The GIXRD analysis shows a residual strain in the Co film of 4%. The difference observed between the local order analysis and the long range order results is explained in terms of the low dimensions of the diffracting domains. The evolution of film strains, as a function of the Co coverage, shows a marked deviation from the elastic strain theory. Modification of the strain field in the Co film as a function of the Au coverage is studied by GIXRD analysis. The Au growth study, at R.T., shows no evidence of a Au/Co mixing in the case of the Au/Co interface. The Au overlayer adopts a twinned face centred cubic structure on the rough Co film surface. (author)

  17. Indium oxide inverse opal films synthesized by structure replication method

    Science.gov (United States)

    Amrehn, Sabrina; Berghoff, Daniel; Nikitin, Andreas; Reichelt, Matthias; Wu, Xia; Meier, Torsten; Wagner, Thorsten

    2016-04-01

    We present the synthesis of indium oxide (In2O3) inverse opal films with photonic stop bands in the visible range by a structure replication method. Artificial opal films made of poly(methyl methacrylate) (PMMA) spheres are utilized as template. The opal films are deposited via sedimentation facilitated by ultrasonication, and then impregnated by indium nitrate solution, which is thermally converted to In2O3 after drying. The quality of the resulting inverse opal film depends on many parameters; in this study the water content of the indium nitrate/PMMA composite after drying is investigated. Comparison of the reflectance spectra recorded by vis-spectroscopy with simulated data shows a good agreement between the peak position and calculated stop band positions for the inverse opals. This synthesis is less complex and highly efficient compared to most other techniques and is suitable for use in many applications.

  18. Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

    OpenAIRE

    Abdalla, Soliman; Al-Marzouki, Fahad; Obaid, Abdullah; Gamal, Salah

    2016-01-01

    Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of...

  19. Tailored high performance shape memory epoxy–silica nanocomposites. Structure design

    Czech Academy of Sciences Publication Activity Database

    Ponyrko, Sergii; Donato, Ricardo Keitel; Matějka, Libor

    2016-01-01

    Roč. 7, č. 3 (2016), s. 560-572 ISSN 1759-9954 R&D Projects: GA ČR(CZ) GAP108/12/1459 Institutional support: RVO:61389013 Keywords : shape-memory polymer * epoxy-silica nanocomposite * shape-memory effect Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.375, year: 2016

  20. Study of the spectra of silica colloidal crystals with assembled silver obtained from a photolysis method

    Science.gov (United States)

    Li, Wenjiang; He, Jinglong; He, Sailing

    2005-02-01

    The colorful artificial 3D silica colloidal crystals (opal) were prepared through self-assembly of silica spheres in the visible frequency range. We directly synthesized nano silver particles in the void of the silica artificial opal film using the photolysis of silver nitrate under UV light, nano silver particles were self-deposited around the surface of silica sphere. The shifts of the stop band of the artificial crystals after exposing different time under UV light were studied. Synthetic silica opal with three-dimensional (3D) structure is potentially useful for the development of diffractive optical devices, micro mechanical systems, and sensory elements because photonic band gaps obtained from self-assembled closely packed periodic structures.

  1. Preparation and characterization of silk/silica hybrid biomaterials by sol-gel crosslinking process

    Energy Technology Data Exchange (ETDEWEB)

    Hou Aiqin, E-mail: aiqinhou@dhu.edu.c [National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, 3H, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China); Chen Huawei [National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, 3H, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China)

    2010-03-15

    The silk/silica hybrid biomaterials are synthesized by sol-gel crosslinking process. The chemical and morphological structures of silk/silica hybrids are investigated with micro-FT-IR spectra, X-ray diffraction, SEM, AFM, and DSC. The results show that the crosslinking reactions among inorganic nano-particles, fibroin and 2,4,6-tri[(2-epihydrin-3-bimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-EBAC) take place during sol-gel process. The silk/silica hybrids form new molecular structures containing not only organic fibroin but also inorganic nano-silica particles. The inorganic particles are bounded to the fibroin through covalent bonds. The silk/silica hybrids can form excellent film with very even nanometer particles. The thermal properties of organic/inorganic hybrid are improved.

  2. Preparation and characterization of silk/silica hybrid biomaterials by sol-gel crosslinking process

    International Nuclear Information System (INIS)

    Hou Aiqin; Chen Huawei

    2010-01-01

    The silk/silica hybrid biomaterials are synthesized by sol-gel crosslinking process. The chemical and morphological structures of silk/silica hybrids are investigated with micro-FT-IR spectra, X-ray diffraction, SEM, AFM, and DSC. The results show that the crosslinking reactions among inorganic nano-particles, fibroin and 2,4,6-tri[(2-epihydrin-3-bimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-EBAC) take place during sol-gel process. The silk/silica hybrids form new molecular structures containing not only organic fibroin but also inorganic nano-silica particles. The inorganic particles are bounded to the fibroin through covalent bonds. The silk/silica hybrids can form excellent film with very even nanometer particles. The thermal properties of organic/inorganic hybrid are improved.

  3. On the formation mechanisms of the diffuse atmospheric pressure dielectric barrier discharge in CVD processes of thin silica-like films

    International Nuclear Information System (INIS)

    Starostin, S A; Premkumar, P Antony; Creatore, M; Van Veldhuizen, E M; Van de Sanden, M C M; De Vries, H; Paffen, R M J

    2009-01-01

    Pathways of formation and temporal evolution of the diffuse dielectric barrier discharge at atmospheric pressure were experimentally studied in this work by means of optical (fast imaging camera) and electrical diagnostics. The chosen model system is relevant for applications of plasma-enhanced chemical vapor deposition of thin silica-like film on the polymeric substrate, from cost-efficient gas mixtures of Ar/N 2 /O 2 /hexamethyldisiloxane. It was found that the discharge can gradually experience the phases of homogeneous low current Townsend-like mode, local Townsend to glow transition and expanding high current density (∼0.7 A cm -2 ) glow-like mode. While the glow-like current spot occupies momentarily only a small part of the electrode area, its expanding behavior provides uniform treatment of the whole substrate surface. Alternatively, it was observed that a visually uniform discharge can be formed by the numerous microdischarges overlapping over the large electrode area.

  4. Two-dimensional silica opens new perspectives

    Science.gov (United States)

    Büchner, Christin; Heyde, Markus

    2017-12-01

    In recent years, silica films have emerged as a novel class of two-dimensional (2D) materials. Several groups succeeded in epitaxial growth of ultrathin SiO2 layers using different growth methods and various substrates. The structures consist of tetrahedral [SiO4] building blocks in two mirror symmetrical planes, connected via oxygen bridges. This arrangement is called a silica bilayer as it is the thinnest 2D arrangement with the stoichiometry SiO2 known today. With all bonds saturated within the nano-sheet, the interaction with the substrate is based on van der Waals forces. Complex ring networks are observed, including hexagonal honeycomb lattices, point defects and domain boundaries, as well as amorphous domains. The network structures are highly tuneable through variation of the substrate, deposition parameters, cooling procedure, introducing dopants or intercalating small species. The amorphous networks and structural defects were resolved with atomic resolution microscopy and modeled with density functional theory and molecular dynamics. Such data contribute to our understanding of the formation and characteristic motifs of glassy systems. Growth studies and doping with other chemical elements reveal ways to tune ring sizes and defects as well as chemical reactivities. The pristine films have been utilized as molecular sieves and for confining molecules in nanocatalysis. Post growth hydroxylation can be used to tweak the reactivity as well. The electronic properties of silica bilayers are favourable for using silica as insulators in 2D material stacks. Due to the fully saturated atomic structure, the bilayer interacts weakly with the substrate and can be described as quasi-freestanding. Recently, a mm-scale film transfer under structure retention has been demonstrated. The chemical and mechanical stability of silica bilayers is very promising for technological applications in 2D heterostacks. Due to the impact of this bilayer system for glass science

  5. In Situ Growth of Mesoporous Silica with Drugs on Titanium Surface and Its Biomedical Applications.

    Science.gov (United States)

    Wan, Mimi; Zhang, Jin; Wang, Qi; Zhan, Shuyue; Chen, Xudong; Mao, Chun; Liu, Yuhong; Shen, Jian

    2017-06-07

    Mesoporous silica has been developed for the modification of titanium surfaces that are used as implant materials. Yet, the traditional modification methods failed to effectively construct mesoporous silica on the titanium surface evenly and firmly, in which the interaction between mesoporous silica and titanium was mainly physical. Here, in situ growth of mesoporous silica on a titanium surface was performed using a simple evaporation-induced self-assembly strategy. Meantime, in situ introduction of drugs (heparin and vancomycin) to mesoporous silica was also adopted to improve the drug-loading amount. Both the above-mentioned processes were completed at the same time. Transmission electron microscopy, N 2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy, scanning electron microscopy, and water contact angle measurements were used to characterize the structure of the mesoporous silica film. Results indicated that the mesoporous silica film that in situ grew on the titanium surface was smooth, thin, transparent, and stable. Cytotoxicity, proliferation performance of osteoblast cells, and in vitro and in vivo studies of the antibacterial activity of the coating were tested. This is the first study to modify the titanium surface by the in situ growth of a mesoporous silica coating with two kinds of drugs. The stability of the mesoporous silica coating can be attributed to the chemical bonding between dopamine and silicon hydroxyl of the mesoporous silica coating, and the smooth surface of mesoporous silica is a result of the method of in situ growth. The large amount of drug-loading also could be ascribed to the in situ introduction of drugs during the synthetic process. The strategy proposed in this work will bring more possibilities for the preparation of advanced functional materials based on the combination of mesoporous structure and metallic materials.

  6. Giant basal spicule from the deep-sea glass sponge Monorhaphis chuni: synthesis of the largest bio-silica structure on Earth by silicatein

    Science.gov (United States)

    Wang, Xiao-hong; Zhang, Xue-hua; Schröder, Heinz C.; Müller, Werner E. G.

    2009-09-01

    Like all sponges (phylum Porifera), the glass sponges (Hexactinellida) are provided with an elaborate and distinct body plan, which relies on a filigree skeleton. It is constructed by an array of morphologically determined elements, the spicules. Schulze described the largest siliceous hexactinellid sponge on Earth, the up to 3 m high Monorhaphis chuni, collected during the German Deep Sea Expedition "Valdivia" (1898-1899). This species develops an equally large bio-silica structure, the giant basal spicule (3 m × 10 mm). Using these spicules as a model, one can obtain the basic knowledge on the morphology, formation, and development of silica skeletal elements. The silica matrix is composed of almost pure silica, endowing it with unusual optophysical properties, which are superior to those of man-made waveguides. Experiments suggest that the spicules function in vivo as a nonocular photoreception system. The spicules are also provided with exceptional mechanical properties. Like demosponges, the hexactinellids synthesize their silica enzymatically via the enzyme silicatein (27 kDa protein). This enzyme is located in/embedded in the silica layers. This knowledge will surely contribute to a further utilization and exploration of silica in biomaterial/biomedical science.

  7. On the controlled isotropic shrinkage induced fine-tuning of photo-luminescence in terbium ions embedded silica inverse opal films

    Science.gov (United States)

    Shrivastava, Vishnu Prasad; Kumar, Jitendra; Sivakumar, Sri

    2017-12-01

    Tb3+ embedded silica inverse opal structures with different photonic stop bands have been fabricated by annealing the SiO2-polystyrene spheres (diameter 390 nm) opal template at 320-650 oC. The PSB tuning realized in the wavelength range 498 - 600 nm is shown to depend on annealing temperature and impending isotropic shrinkage of silica matrix. The impact of wide PSB shift on four Tb3+ ion emission bands (blue, green, yellow, and red at 486, 545, 580, and 620 nm, respectively) corresponding to 5D4→7Fj (j = 6,5,4,3) transitions have been investigated. The effect amounts to significant suppression of emission bands at 586, 545 and 486 nm in inverse opals, obtained by annealing opal template at 350, 400, and 650 oC, respectively. Further, luminescence lifetime of Tb3+ ion 5D4 state increases with shrinkage induced in inverse opal progressively and get enhanced up to 2.3 times vis-à-vis reference silica. The changes in refractive index caused by thermal annealing of opal template is found to be responsible for the observed improvement in 5D4 state lifetime.

  8. Structural and Luminescence Properties of Lu2O3:Eu3+ F127 Tri-Block Copolymer Modified Thin Films Prepared by Sol-Gel Method

    Science.gov (United States)

    de Jesus Morales Ramírez, Angel; Hernández, Margarita García; Murillo, Antonieta García; de Jesús Carrillo Romo, Felipe; Palmerin, Joel Moreno; Velazquez, Dulce Yolotzin Medina; Jota, María Luz Carrera

    2013-01-01

    Lu2O3:Eu3+ transparent, high density, and optical quality thin films were prepared using the sol-gel dip-coating technique, starting with lutetium and europium nitrates as precursors and followed by hydrolysis in an ethanol-ethylene glycol solution. Acetic acid and acetylacetonate were incorporated in order to adjust pH and as a sol stabilizer. In order to increment the thickness of the films and orient the structure, F127 Pluronic acid was incorporated during the sol formation. Structural, morphological, and optical properties of the films were investigated for different F127/Lu molar ratios (0–5) in order to obtain high optical quality films with enhanced thickness compared with the traditional method. X-ray diffraction (XRD) shows that the films present a highly oriented cubic structure beyond 1073 K for a 3-layer film, on silica glass substrates. The thickness, density, porosity, and refractive index evolution of the films were investigated by means of m-lines microscopy along with the morphology by scanning electron microscope (SEM) and luminescent properties. PMID:28809336

  9. Thin film epitaxy and structure property correlations for non-polar ZnO films

    International Nuclear Information System (INIS)

    Pant, P.; Budai, J.D.; Aggarwal, R.; Narayan, Roger J.; Narayan, J.

    2009-01-01

    Heteroepitaxial growth and strain relaxation were investigated in non-polar a-plane (1 1 -2 0)ZnO films grown on r-plane (1 0 -1 2)sapphire substrates in the temperature range 200-700 deg. C by pulsed laser deposition. The lattice misfit in the plane of the film for this orientation varied from -1.26% in [0 0 0 1] to -18.52% in the [-1 1 0 0] direction. The alignment of (1 1 -2 0)ZnO planes parallel to (1 0 -1 2)sapphire planes was confirmed by X-ray diffraction θ-2θ scans over the entire temperature range. X-ray φ-scans revealed the epitaxial relationship:[0 0 0 1]ZnO-parallel [-1 1 0 1]sap; [-1 1 0 0]ZnO-parallel [-1 -1 2 0]sap. Depending on the growth temperature, variations in the structural, optical and electrical properties were observed in the grown films. Room temperature photoluminescence for films grown at 700 deg. C shows a strong band-edge emission. The ratio of the band-edge emission to green band emission is 135:1, indicating reduced defects and excellent optical quality of the films. The resistivity data for the films grown at 700 deg. C shows semiconducting behavior with room temperature resistivity of 2.2 x 10 -3 Ω-cm.

  10. Luminescence and structural study of porous silicon films

    Science.gov (United States)

    Xie, Y. H.; Wilson, W. L.; Ross, F. M.; Mucha, J. A.; Fitzgerald, E. A.; Macaulay, J. M.; Harris, T. D.

    1992-03-01

    A combination of photoluminescence, TEM, and Fourier transform IR spectroscopy is used to investigate the luminescence properties of 3-micron thick, strongly emitting, and highly porous silicon films. TEMs indicate that these samples have structures of predominantly 6-7-nm size clusters. In the as-prepared films, there is a significant concentration of Si-H bonds which is gradually replaced by Si-O bonds during prolonged aging in air. Upon optical excitation these films exhibit strong visible emission, peaking at about 690 nm. The excitation edge is shown to be emission-wavelength dependent, revealing the inhomogeneous nature of both the initially photoexcited and luminescing species. The correlation of the spectral and structural information suggest that the source of the large blue shift of the visible emission compared to the bulk Si bandgap energy is due to quantum confinement in the nanometer-size Si clusters.

  11. Tribological properties of coating films for core structure of HTGR

    International Nuclear Information System (INIS)

    Ozawa, Kenji; Kikuchi, Akiyoshi; Kawakami, Haruo

    1985-01-01

    The tribological properties of the various coating films used for the in-core structures of a high temperature gas-cooled experimental reactor were examined. When the explosion sprayed films of chrome carbide were applied for preventing galling in core restraining mechanism, the hardness of substrate materials exerted influence on the strength of the coating films. Also the effect of the surface roughness of the plasma sprayed films of zirconia on the sliding characteristics of the zirconia films and PGX graphite used for support plates was clarified. The coefficient of friction and the dependence of the amount of wear on surface pressure of these materials were examined. These results have been effectively utilized for the design of the test bodies of HENDEL-T2. In helium atmosphere, oxide film is hard to be formed on metal surface, especially on the contact surface of metals exposed to high temperature, there is the possibility to cause adhesion due to mutual diffusion and galling in sliding. As the means to prevent those, ceramic coating has been attempted. Sliding test, high pressure joining test, thermal cycle test and corrosion test in helium were carried out to evaluate the properties. (Koko, I.)

  12. Structural and electrical properties of CZTS thin films by electrodeposition

    Science.gov (United States)

    Rao, M. C.; Basha, Sk. Shahenoor

    2018-06-01

    CZTS (Cu2ZnSnS4) thin films were coated on ITO glass substrates by single bath electrodeposition technique. The prepared films were subsequently characterized by XRD, SEM, FTIR, UV-visible spectroscopy and Raman studies. The thickness of the thin films was measured by wedge method. X-ray diffraction studies revealed the formation of polycrystalline phase. The morphological surface of the prepared thin films was examined by SEM and AFM and showed the presence of microcrystals on the surface of the samples. The elemental analysis and their compositional ratios present in the samples were confirmed by the energy dispersive X-ray analysis. Functional groups and the position of band structure involved in the materials were confirmed by FTIR. Optical absorption studies were performed on the prepared thin films in the wavelength ranging from 300 to 1000 nm and the energy bandgap values were found to be in the range from 1.39 to 1.60 eV. Raman spectral peak which was observed at 360 cm-1 correspond to kesterite phase, was formed due to the vibration of the molecules. Electrical measurements confirmed the nature of the thin film depending on the charge concentration present in the samples.

  13. Magnetic structure of Tb-Fe films with an artificially layered structure

    International Nuclear Information System (INIS)

    Yamauchi, K.; Habu, K.; Sato, N.

    1988-01-01

    The magnetic structure of Tb-Fe films with an artificially layered structure has been investigated by measuring the temperature dependence of the magnetization of the films. Ferrimagnetic coupling between Tb and Fe through the interface was explicitly observed up to about 9-A Tb and 10-A Fe layers. Films with thinner Tb and Fe layers than these thicknesses are composed of only ferrimagnetically coupled Tb-Fe regions. Films with thicker layers of Tb and Fe are composed of ferrimagnetically coupled Tb-Fe, ferromagnetic Fe, ferromagnetic Tb, and/or magnetically compensated Tb regions. The Tb-Fe films exhibit various temperature dependencies of the magnetization corresponding to these magnetic structures

  14. Improvement in photoconductor film properties by changing dielectric layer structures

    International Nuclear Information System (INIS)

    Kim, S; Oh, K; Lee, Y; Jung, J; Cho, G; Jang, G; Cha, B; Nam, S; Park, J

    2011-01-01

    In recent times, digital X-ray detectors have been actively applied to the medical field; for example, digital radiography offers the potential of improved image quality and provides opportunities for advances in medical image management, computer-aided diagnosis and teleradiology. In this study, two candidate materials (HgI 2 and PbI 2 ) have been employed to study the influence of the dielectric structure on the performance of fabricated X-ray photoconducting films. Parylene C with high permittivity was deposited as a dielectric layer using a parylene deposition system (PDS 2060). The structural and morphological properties of the samples were evaluated field emission scanning electron microscopy and X-ray diffraction. Further, to investigate improvements in the electrical characteristics, a dark current in the dark room and sensitivity to X-ray exposure in the energy range of general radiography diagnosis were measured across the range of the operating voltage. The electric signals varied with the dielectric layer structure of the X-ray films. The PbI 2 film with a bottom dielectric layer showed optimized electric properties. On the other hand, in the case of HgI 2 , the film with a top dielectric layer showed superior electric characteristics. Further, although the sensitivity of the film decreased, the total electrical efficiency of the film improved as a result of the decrease in dark current. When a dielectric layer is deposited on a photoconductor, the properties of the photoconductor, such as hole-electron mobility, should be considered to improve the image quality in digital medical imaging application. In this study, we have thus demonstrated that the use of dielectric layer structures improves the performance of photoconductors.

  15. Nuclear microanalysis of oxide films on structural steel

    International Nuclear Information System (INIS)

    Istomin, I.V.; Karabash, V.A.; Maisyukov, V.D.; Sosnin, A.N.; Shorin, V.S.

    1989-01-01

    Studies of the behavior of structural materials in nuclear power plants have indicated the important role of oxide films on metals, especially metals of the iron group. The films may be formed as a result of the corrosion of the metal in an aggressive coolant. At the same time, some oxide films have anticorrosive properties and can be produced specially by the introduction of inhibitor-passivators, e.g., molecular oxygen, into the aggressive medium. Experimental data on the film growth rate make it possible to determine the kinetics of the oxidation process, the nature of the diffusion of the main components through the film, and the role of the phase transitions (crystal-chemical transformations) and point defects during the migration of oxygen and metal ions through the oxide. In this study nuclear microanalysis is used to measure the parameters of oxide films formed on 10Cr2Mo and 1Cr18Ni10Ti steels in steam in the temperature range 320-620C. In this method the film parameters in the general analysis of the energy spectra of deuterons back-scattered from iron nuclei and protons in the case of the 16 O(d,p 1 ) 17 O nuclear reaction. With this approach and an initial deuteron energy E o = 0.9 MeV the range of the measurable thickness t of the films is 0.001-1.5 mg/cm 2 . The data obtained not only confirm the high sensitivity of the nuclear microanalysis method but also demonstrate that it can be used for nondestructive quality control of the surface

  16. Study of the structure of 3D-ordered macroporous GaN-ZnS:Mn nanocomposite films

    Energy Technology Data Exchange (ETDEWEB)

    Kurdyukov, D. A., E-mail: kurd@gvg.ioffe.ru; Shishkin, I. I.; Grudinkin, S. A.; Sitnikova, A. A.; Zamoryanskaya, M. V.; Golubev, V. G. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2015-05-15

    A film-type 3D-ordered macroporous GaN-ZnS:Mn nanocomposite with the structure of an inverted opal is fabricated. Structural studies of the nanocomposite are performed, and it is shown that GaN and ZnS:Mn introduced into the pores of the silica opal are nanocrystallites misoriented with respect to each other. It is shown that the nanocomposite is a structurally perfect 3D photonic crystal. The efficiency of using a buffer of GaN crystallites to preclude interaction between the surface of the spherical a-SiO{sub 2} particles forming the opal matrix and chemically active substances introduced into the pores is demonstrated.

  17. Pressure dependence of the interfacial structure of potassium chloride films on iron

    International Nuclear Information System (INIS)

    Olson, Dustin; Gao, Hongyu; Tang, Chun; Tysoe, Wilfred T.; Martini, Ashlie

    2015-01-01

    Potassium chloride films on a clean iron surface are used as a model system to explore the interfacial structure of the films and the dependence of that structure on film thickness and pressure. The interfacial structure of one-, two-, three- and four-layer films is measured experimentally using low-energy electron diffraction. Those findings are then complemented by molecular dynamics simulations in which the atomic interaction between the film and substrate is tuned to match film thickness-dependent sublimation activation energy obtained from temperature-programmed desorption measurements. The resultant simulation reliably predicts the structure of thicker films and is then used to study the effect of pressure on the distribution of the lattice constant within and between each layer of the potassium chloride films. Findings indicate that both film thickness and pressure affect the structure within the films as well as the degree of registry between the film and adjacent substrate. - Highlights: • KCl films on an Fe surface are used as a model system to explore interfacial structure • Thin film structure is measured using low-energy electron diffraction • An empirical potential is tuned to match sublimation activation energy • Simulations reveal the effect of pressure on the lattice constant within the KCl films • Pressure affects the film structure and registry between film and substrate

  18. Pressure dependence of the interfacial structure of potassium chloride films on iron

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Dustin [Department of Chemistry and Laboratory for Surface Studies, University of Wisconsin—Milwaukee, Milwaukee, WI 53211 (United States); Gao, Hongyu; Tang, Chun [School of Engineering, University of California Merced, Merced CA 95343 (United States); Tysoe, Wilfred T. [Department of Chemistry and Laboratory for Surface Studies, University of Wisconsin—Milwaukee, Milwaukee, WI 53211 (United States); Martini, Ashlie [School of Engineering, University of California Merced, Merced CA 95343 (United States)

    2015-10-30

    Potassium chloride films on a clean iron surface are used as a model system to explore the interfacial structure of the films and the dependence of that structure on film thickness and pressure. The interfacial structure of one-, two-, three- and four-layer films is measured experimentally using low-energy electron diffraction. Those findings are then complemented by molecular dynamics simulations in which the atomic interaction between the film and substrate is tuned to match film thickness-dependent sublimation activation energy obtained from temperature-programmed desorption measurements. The resultant simulation reliably predicts the structure of thicker films and is then used to study the effect of pressure on the distribution of the lattice constant within and between each layer of the potassium chloride films. Findings indicate that both film thickness and pressure affect the structure within the films as well as the degree of registry between the film and adjacent substrate. - Highlights: • KCl films on an Fe surface are used as a model system to explore interfacial structure • Thin film structure is measured using low-energy electron diffraction • An empirical potential is tuned to match sublimation activation energy • Simulations reveal the effect of pressure on the lattice constant within the KCl films • Pressure affects the film structure and registry between film and substrate.

  19. Investigation of safety margin for turbine generator foundation affected by Alkali Silica reaction based on non-linear structure analysis

    International Nuclear Information System (INIS)

    Shimizu, H.; Asai, Y.; Hosokawa, T.; Sekimoto, H.; Sato, K.; Oshima, R.; Takiguchi, K.; Masuda, Y.; Nishiguchi, I.

    2005-01-01

    A turbine generator foundation is a reinforced concrete structure having a table deck and columns to support equipments. After operation of the plant, the expansion of the table deck in turbine longitudinal axis has been observed. By investigation of concrete material properties, it was found that the expansion has been caused by alkali-silica reaction. This study has been performed to evaluate the safety allowance of strength capacity of the turbine generator foundation by nonlinear analysis using beam element model with elongation, rebar strain and material properties data which have been measured for almost 30 years in actual foundation. (authors)

  20. Control of silicification by genetically engineered fusion proteins: silk-silica binding peptides.

    Science.gov (United States)

    Zhou, Shun; Huang, Wenwen; Belton, David J; Simmons, Leo O; Perry, Carole C; Wang, Xiaoqin; Kaplan, David L

    2015-03-01

    In the present study, an artificial spider silk gene, 6mer, derived from the consensus sequence of Nephila clavipes dragline silk gene, was fused with different silica-binding peptides (SiBPs), A1, A3 and R5, to study the impact of the fusion protein sequence chemistry on silica formation and the ability to generate a silk-silica composite in two different bioinspired silicification systems: solution-solution and solution-solid. Condensed silica nanoscale particles (600-800 nm) were formed in the presence of the recombinant silk and chimeras, which were smaller than those formed by 15mer-SiBP chimeras, revealing that the molecular weight of the silk domain correlated to the sizes of the condensed silica particles in the solution system. In addition, the chimeras (6mer-A1/A3/R5) produced smaller condensed silica particles than the control (6mer), revealing that the silica particle size formed in the solution system is controlled by the size of protein assemblies in solution. In the solution-solid interface system, silicification reactions were performed on the surface of films fabricated from the recombinant silk proteins and chimeras and then treated to induce β-sheet formation. A higher density of condensed silica formed on the films containing the lowest β-sheet content while the films with the highest β-sheet content precipitated the lowest density of silica, revealing an inverse correlation between the β-sheet secondary structure and the silica content formed on the films. Intriguingly, the 6mer-A3 showed the highest rate of silica condensation but the lowest density of silica deposition on the films, compared with 6mer-A1 and -R5, revealing antagonistic crosstalk between the silk and the SiBP domains in terms of protein assembly. These findings offer a path forward in the tailoring of biopolymer-silica composites for biomaterial related needs. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. Optical and structural behaviors of crosslinked polyvinyl alcohol thin films

    Science.gov (United States)

    Pandit, Subhankar; Kundu, Sarathi

    2018-04-01

    Polyvinyl Alcohol (PVA) has excellent properties like uniaxial tensile stress, chemical resistance, biocompatibility, etc. The properties of PVA further can be tuned by crosslinking process. In this work, a simple heat treatment method is used to find out the optimum crosslinking of PVA and the corresponding structural and optical responses are explored. The PVA crosslinking is done by exposing the films at different temperatures and time intervals. The optical property of pure and heat treated PVA films are investigated by UV-Vis absorption and photoluminescence emission spectroscopy and structural modifications are studied by Fourier Transform Infrared Spectroscopy (FTIR). The absorption peaks of pure PVA are observed at ≈ 280 and 335 nm and the corresponding emission is observed at ≈ 424 nm. The pure PVA showed modified optical behaviors after the heat treatment. In addition, dipping the PVA films in hot water (85°C) for nearly 20 minutes also show impact on both structural and optical properties. From FTIR spectroscopy, the changes in vibrational band positions confirm the structural modifications of PVA films.

  2. Highly stable thin film transistors using multilayer channel structure

    KAUST Repository

    Nayak, Pradipta K.; Wang, Zhenwei; Anjum, Dalaver H.; Hedhili, Mohamed N.; Alshareef, Husam N.

    2015-01-01

    We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured

  3. Titanate-silica mesostructured nanocables: synthesis, structural analysis and biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Su Yonghua; Sheng Jiayu; Ling Changquan [Department of Traditional Chinese Medicine, Changhai Hospital, The Second Military Medical University, 168 Changhai Road, Shanghai 200433 (China); Qiao Shizhang; Jin Yonggang; Stahr, Frances; Cheng Lina; Lu Gao Qing [ARC Centre of Excellence for Functional Nanomaterials, Australian Institute for Bioengineering and Nanotechnology, and School of Chemical Engineering, University of Queensland, QLD 4072 (Australia); Yang Huagui; Yang Chen, E-mail: s.qiao@uq.edu.au, E-mail: lingchangquan@smmu.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2010-02-10

    1D hierarchical composite mesostructures of titanate and silica were synthesized via an interfacial surfactant templating approach. Such mesostructures have complex core-shell architectures consisting of single-crystalline H{sub 2}Ti{sub 3}O{sub 7} nanobelts inside the ordered mesoporous SiO{sub 2} shell, which are nontoxic and highly biocompatible. The overall diameter of as-prepared 1D hierarchical composite mesostructures is only approx. 34.2 nm with a length over 500 nm on average. A model to explain the formation mechanism of these mesostructures has been proposed; the negatively charged surface of H{sub 2}Ti{sub 3}O{sub 7} nanobelts controls the formation of the octadecyltrimethylammonium bromide (C{sub 18}TAB) bilayer, which in turn regulates the cooperative self-assembly of silica and C{sub 18}TAB complex micelles on the interface to produce a mesoporous silica shell. More importantly, the application of synthesized mesostructured nanocables as anticancer drug reservoirs has also been explored, which indicates that the membranes containing these mesoporous nanocables have a great potential to be used as transdermal drug delivery systems.

  4. Titanate-silica mesostructured nanocables: synthesis, structural analysis and biomedical applications

    Science.gov (United States)

    Su, Yonghua; Qiao, Shizhang; Yang, Huagui; Yang, Chen; Jin, Yonggang; Stahr, Frances; Sheng, Jiayu; Cheng, Lina; Ling, Changquan; Qing Lu, Gao

    2010-02-01

    1D hierarchical composite mesostructures of titanate and silica were synthesized via an interfacial surfactant templating approach. Such mesostructures have complex core-shell architectures consisting of single-crystalline H2Ti3O7 nanobelts inside the ordered mesoporous SiO2 shell, which are nontoxic and highly biocompatible. The overall diameter of as-prepared 1D hierarchical composite mesostructures is only approx. 34.2 nm with a length over 500 nm on average. A model to explain the formation mechanism of these mesostructures has been proposed; the negatively charged surface of H2Ti3O7 nanobelts controls the formation of the octadecyltrimethylammonium bromide (C18TAB) bilayer, which in turn regulates the cooperative self-assembly of silica and C18TAB complex micelles on the interface to produce a mesoporous silica shell. More importantly, the application of synthesized mesostructured nanocables as anticancer drug reservoirs has also been explored, which indicates that the membranes containing these mesoporous nanocables have a great potential to be used as transdermal drug delivery systems.

  5. Titanate-silica mesostructured nanocables: synthesis, structural analysis and biomedical applications

    International Nuclear Information System (INIS)

    Su Yonghua; Sheng Jiayu; Ling Changquan; Qiao Shizhang; Jin Yonggang; Stahr, Frances; Cheng Lina; Lu Gao Qing; Yang Huagui; Yang Chen

    2010-01-01

    1D hierarchical composite mesostructures of titanate and silica were synthesized via an interfacial surfactant templating approach. Such mesostructures have complex core-shell architectures consisting of single-crystalline H 2 Ti 3 O 7 nanobelts inside the ordered mesoporous SiO 2 shell, which are nontoxic and highly biocompatible. The overall diameter of as-prepared 1D hierarchical composite mesostructures is only approx. 34.2 nm with a length over 500 nm on average. A model to explain the formation mechanism of these mesostructures has been proposed; the negatively charged surface of H 2 Ti 3 O 7 nanobelts controls the formation of the octadecyltrimethylammonium bromide (C 18 TAB) bilayer, which in turn regulates the cooperative self-assembly of silica and C 18 TAB complex micelles on the interface to produce a mesoporous silica shell. More importantly, the application of synthesized mesostructured nanocables as anticancer drug reservoirs has also been explored, which indicates that the membranes containing these mesoporous nanocables have a great potential to be used as transdermal drug delivery systems.

  6. Oxide ultrathin films science and technology

    CERN Document Server

    Pacchioni, Gianfranco

    2012-01-01

    A wealth of information in one accessible book. Written by international experts from multidisciplinary fields, this in-depth exploration of oxide ultrathin films covers all aspects of these systems, starting with preparation and characterization, and going on to geometrical and electronic structure, as well as applications in current and future systems and devices. From the Contents: Synthesis and Preparation of Oxide Ultrathin Films Characterization Tools of Oxide Ultrathin Films Ordered Oxide Nanostructures on Metal Surfaces Unusual Properties of Oxides and Other Insulators in the Ultrathin Limit Silica and High-K Dielectrics Thin Films in Microelectronics Oxide Passive Films and Corrosion Protection Oxide Films as Catalytic Materials and as Models of Real Catalysts Oxide Films in Spintronics Oxide Ultrathin Films in Solid Oxide Fuel Cells Transparent Conducting and Chromogenic Oxide Films as Solar Energy Materials Oxide Ultrathin Films in Sensor Applications Ferroelectricity in Ultrathin Film Capacitors T...

  7. Crystal structure of red lead titanate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bursill, L.A.; Peng, J.L.; Jiang, B. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Li, X. [Jilin Univ., Changchun, JL (China). Dept of Chemistry

    1998-09-01

    Orange-red lead titanate thin films are examined by high-resolution transmission electron microscopy and diffraction. It is remarkable that the structure is based on that of tetragonal-tungsten-bronze (TTB) rather than perovskite-type. The chemical basis for this result is examined. It is deduced that the TTB structure is stabilized by inclusion of hydroxyl ions during synthesis by a sol-gel route involving hydrolysis of n-Butyl titanate 7 refs., 1 tab., 4 figs.

  8. Crystal structure of red lead titanate thin films

    International Nuclear Information System (INIS)

    Bursill, L.A.; Peng, J.L.; Jiang, B.; Li, X.

    1998-01-01

    Orange-red lead titanate thin films are examined by high-resolution transmission electron microscopy and diffraction. It is remarkable that the structure is based on that of tetragonal-tungsten-bronze (TTB) rather than perovskite-type. The chemical basis for this result is examined. It is deduced that the TTB structure is stabilized by inclusion of hydroxyl ions during synthesis by a sol-gel route involving hydrolysis of n-Butyl titanate

  9. Domain structure and magnetotransport in epitaxial colossal magnetoresistance thin films

    OpenAIRE

    Suzuki, Yuri; Wu, Yan; Yu, Jun; Rüdiger, Ulrich; Kent, Andrew D.; Nath, Tapan K.; Eom, Chang-Beom

    2000-01-01

    Our studies of compressively strained La0.7 Sr0.3 MnO7 (LSMO) thin films reveal the importance of domain structure and strain effects in the magnetization reversal and magnetotransport. Normal and grazing incidence x-ray diffraction indicate that the compressive strain on these LSMO thin films on (100) LaAlO3 is not completely relaxed up to thicknesses on the order of 1000 Å. The effect of the compressive strain is evident in the shape of the magnetization loops and the magnetotransport measu...

  10. Miniature all-silica optical fiber pressure sensor with an ultrathin uniform diaphragm.

    Science.gov (United States)

    Wang, Wenhui; Wu, Nan; Tian, Ye; Niezrecki, Christopher; Wang, Xingwei

    2010-04-26

    This paper presents an all-silica miniature optical fiber pressure/acoustic sensor based on the Fabry-Perot (FP) interferometric principle. The endface of the etched optical fiber tip and silica thin diaphragm on it form the FP structure. The uniform and thin silica diaphragm was fabricated by etching away the silicon substrate from a commercial silicon wafer that has a thermal oxide layer. The thin film was directly thermally bonded to the endface of the optical fiber thus creating the Fabry-Perot cavity. Thin films with a thickness from 1microm to 3microm have been bonded successfully. The sensor shows good linearity and hysteresis during measurement. A sensor with 0.75 microm-thick diaphragm thinned by post silica etching was demonstrated to have a sensitivity of 11 nm/kPa. The new sensor has great potential to be used as a non-intrusive pressure sensor in a variety of sensing applications.

  11. Structural and magnetic study of CoCr{sub 2}O{sub 4} thin films obtained by employing the sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Del Toro, A.D.; Garcia, R.P.; Davila, Y.G.; Gomes, J.L.; Goncalves, L.P.; Hernandez, E.P. [Universidade Federal de Pernambuco (UFPE), PE (Brazil)

    2016-07-01

    Full text: In this work we made a study about the structural and magnetic properties of cobalt chromite. We obtained samples in a film format and also in chromite nanopowder. Both, the powder and films were fabricated by the sol-gel chemical method, the film were deposited by the spin coating technique followed by an appropriate heat treatment at 500 °C. The used substrate was glass based on silica and we studied the rotating speed parameter during deposition. The initial aim of the work was the study of the influence of rotating speed on the quality of cromite films. The crystallinity of samples was confirmed by diffraction X-ray (XRD). The lattice parameters were determined using the Rietveld method from which we calculate grain size of 8.6 nm. The scanning electron microscopy (SEM) showed granular films with good homogeneity and we observed the dependence of the rotating speed on the quality of the deposited films. The magnetic properties were measured using a vibrating sample magnetometer (VSM). For powder samples we obtained Curie temperature of 94 K, which is a phase transition from ferrimagnetic to paramagnetic. The applied magnetic field during in the characterization of the film was oriented parallel to the plane of the substrate and we observed a high coercivity. The Curie temperature value for the films was 93 K, similar to the powder samples. (author)

  12. Mechanism of Solder Joint Cracks in Anisotropic Conductive Films Bonding and Solutions: Delaying Hot-Bar Lift-Up Time and Adding Silica Fillers

    Directory of Open Access Journals (Sweden)

    Shuye Zhang

    2018-01-01

    Full Text Available Micron sizes solder metallurgical joints have been applied in a thin film application of anisotropic conductive film and benefited three general advantages, such as lower joint resistance, higher power handling capability, and reliability, when compared with pressure based contact of metal conductor balls. Recently, flex-on-board interconnection has become more and more popular for mobile electronic applications. However, crack formation of the solder joint crack was occurred at low temperature curable acrylic polymer resins after bonding processes. In this study, the mechanism of SnBi58 solder joint crack at low temperature curable acrylic adhesive was investigated. In addition, SnBi58 solder joint cracks can be significantly removed by increasing the storage modulus of adhesives instead of coefficient of thermal expansion. The first approach of reducing the amount of polymer rebound can be achieved by using an ultrasonic bonding method to maintain a bonding pressure on the SnBi58 solder joints cooling to room temperature. The second approach is to increase storage modulus of adhesives by adding silica filler into acrylic polymer resins to prevent the solder joint from cracking. Finally, excellent acrylic based SnBi58 solder joints reliability were obtained after 1000 cycles thermal cycling test.

  13. Optimum deposition, structure, and properties of tantalum oxide films

    International Nuclear Information System (INIS)

    Lin, Y.C.

    1985-01-01

    Amorphous, ductile, and uniform Ta 2 O 5 films that acted as diffusion barriers were developed by sputter depositing Ta metal on Al single crystals (99.99%) and subsequently anodizing these thin films. The morphology, microstructure, composition and properties were characterized by scanning and transmission electron microscopy, surface and Fourier transform infrared spectroscopy, X-ray diffraction, and fluorescence. Superior corrosion resistance in a water saturated Cl 2 atmosphere was provided by Ta 2 O 5 coating on Al single crystal substrates but not on Al alloys. The strong Ta-O bond, the non-porous nature of the film and good adhesion to the substrate are attributed to the outstanding corrosion resistance of these oxide coatings. Al alloy surfaces are not protected, since the anodic film formed over grain boundaries, processing lines and emergent precipitates is poorly adherent, thus providing loci for corrosion. These problems were eliminated by casting a 400 A layer of tantalum oxyhydroxide polymer from ethanol solution onto Al substrate and curing to a Ta 2 O 5 layer that effectively resisted attack by wet Cl 2 . The mechanical properties of Ta 2 O 5 films on Al alloys were studied at various pH's by in-situ fatigue loading coupled with electrochemical measurements of corrosion potential and corrosion current. These results indicate the fatigue resistance of this oxide film effectively protects the underlying metal from strong HCl solution attack. The very unusual ductility and high corrosion resistance of Ta 2 O 5 films could be related to the graphite-like structure that exists in the amorphous state of this oxide

  14. Metal induced crystallization of amorphous silicon thin films studied by x-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

    Naidu, K Lakshun; Mohiddon, Md Ahamad; Dalba, G; Krishna, M Ghanashyam; Rocca, F

    2013-01-01

    The role of thin metallic layer (Chromium or Nickel) in the crystallization of a-Si film has been studied using X-ray absorption fine structure spectroscopy (XAFS). The films were grown at different substrate temperatures in two different geometrical structures : (a) a 200 nm metal layer (Cr or Ni) was deposited on fused silica (FS) followed by 400 nm of a-Si and (b) the 400 nm a-Si layer was deposited on FS followed by 200 nm of metal layer. XAFS measurements at Cr K-edge and Ni K-edge were done at BM08 – GILDA beamline of the European Synchrotron Research Facility (ESRF, Grenoble, F) in fluorescence mode. To understand the evolution of the local structure of Cr/Ni diffusing from bottom to top and from top to bottom, total reflection and higher incidence angles were employed. The relative content of metal, metal oxide and metal silicides compounds on the upper surface and/or in the bulk of different films has been evaluated as a function of thermal treatment.

  15. Ionic liquids as dynamic templating agents for sol-gel silica systems: synergistic anion and cation effect on the silica structured growth

    Czech Academy of Sciences Publication Activity Database

    Donato, K. Z.; Donato, Ricardo Keitel; Lavorgna, M.; Ambrosio, L.; Matějka, Libor; Mauler, R. S.; Schrekker, H. S.

    2015-01-01

    Roč. 76, č. 2 (2015), s. 414-427 ISSN 0928-0707 R&D Projects: GA ČR GAP108/12/1459 Institutional support: RVO:61389013 Keywords : silica * imidazolium ionic liquid * sol-gel Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.473, year: 2015

  16. Gamma Radiation Dosimetry Using Tellurium Dioxide Thin Film Structures

    Directory of Open Access Journals (Sweden)

    Olga Korostynska

    2002-08-01

    Full Text Available Thin films of Tellurium dioxide (TeO2 were investigated for γ-radiation dosimetry purposes. Samples were fabricated using thin film vapour deposition technique. Thin films of TeO2 were exposed to a 60Co γ-radiation source at a dose rate of 6 Gy/min at room temperature. Absorption spectra for TeO2 films were recorded and the values of the optical band gap and energies of the localized states for as-deposited and γ-irradiated samples were calculated. It was found that the optical band gap values were decreased as the radiation dose was increased. Samples with electrical contacts having a planar structure showed a linear increase in current values with the increase in radiation dose up to a certain dose level. The observed changes in both the optical and the electrical properties suggest that TeO2 thin film may be considered as an effective material for room temperature real time γ-radiation dosimetry.

  17. Structural and optical properties of electrodeposited molybdenum oxide thin films

    International Nuclear Information System (INIS)

    Patil, R.S.; Uplane, M.D.; Patil, P.S.

    2006-01-01

    Electrosynthesis of Mo(IV) oxide thin films on F-doped SnO 2 conducting glass (10-20/Ω/□) substrates were carried from aqueous alkaline solution of ammonium molybdate at room temperature. The physical characterization of as-deposited films carried by thermogravimetric/differential thermogravimetric analysis (TGA/DTA), infrared spectroscopy and X-ray diffraction (XRD) showed the formation of hydrous and amorphous MoO 2 . Scanning electron microscopy (SEM) revealed a smooth but cracked surface with multi-layered growth. Annealing of these films in dry argon at 450 deg. C for 1 h resulted into polycrystalline MoO 2 with crystallites aligned perpendicular to the substrate. Optical absorption study indicated a direct band gap of 2.83 eV. The band gap variation consistent with Moss rule and band gap narrowing upon crystallization was observed. Structure tailoring of as-deposited thin films by thermal oxidation in ambient air to obtain electrochromic Mo(VI) oxide thin films was exploited for the first time by this novel route. The results of this study will be reported elsewhere

  18. Accurately controlled sequential self-folding structures by polystyrene film

    Science.gov (United States)

    Deng, Dongping; Yang, Yang; Chen, Yong; Lan, Xing; Tice, Jesse

    2017-08-01

    Four-dimensional (4D) printing overcomes the traditional fabrication limitations by designing heterogeneous materials to enable the printed structures evolve over time (the fourth dimension) under external stimuli. Here, we present a simple 4D printing of self-folding structures that can be sequentially and accurately folded. When heated above their glass transition temperature pre-strained polystyrene films shrink along the XY plane. In our process silver ink traces printed on the film are used to provide heat stimuli by conducting current to trigger the self-folding behavior. The parameters affecting the folding process are studied and discussed. Sequential folding and accurately controlled folding angles are achieved by using printed ink traces and angle lock design. Theoretical analyses are done to guide the design of the folding processes. Programmable structures such as a lock and a three-dimensional antenna are achieved to test the feasibility and potential applications of this method. These self-folding structures change their shapes after fabrication under controlled stimuli (electric current) and have potential applications in the fields of electronics, consumer devices, and robotics. Our design and fabrication method provides an easy way by using silver ink printed on polystyrene films to 4D print self-folding structures for electrically induced sequential folding with angular control.

  19. Study of silica sol-gel materials for sensor development

    Science.gov (United States)

    Lei, Qiong

    Silica sol-gel is a transparent, highly porous silicon oxide glass made at room temperature by sol-gel process. The name of silica sol-gel comes from the observable physical phase transition from liquid sol to solid gel during its preparation. Silica sol-gel is chemically inert, thermally stable, and photostable, it can be fabricated into different desired shapes during or after gelation, and its porous structure allows encapsulation of guest molecules either before or after gelation while still retaining their functions and sensitivities to surrounding environments. All those distinctive features make silica sol-gel ideal for sensor development. Study of guest-host interactions in silica sol-gel is important for silica-based sensor development, because it helps to tailor local environments inside sol-gel matrix so that higher guest loading, longer shelf-life, higher sensitivity and faster response of silica gel based sensors could be achieved. We focused on pore surface modification of two different types of silica sol-gel by post-grafting method, and construction of stable silica hydrogel-like thin films for sensor development. By monitoring the mobility and photostability of rhodamine 6G (R6G) molecules in silica alcogel thin films through single molecule spectroscopy (SMS), the guest-host interactions altered by post-synthesis grafting were examined. While physical confinement remains the major factor that controls mobility in modified alcogels, both R6G mobility and photostability register discernable changes after surface charges are respectively reversed and neutralized by aminopropyltriethoxysilane (APTS) and methyltriethoxysilane (MTES) grafting. The change in R6G photostability was found to be more sensitive to surface grafting than that of mobility. In addition, silica film modification by 0.4% APTS is as efficient as that by pure MTES in lowering R6G photostability, which suggests that surface charge reversal is more effective than charge neutralization

  20. Microporous silica prepared by organic templating: relationship between the molecular template and pore structure

    International Nuclear Information System (INIS)

    Brinker, C. Jeffrey; Cao, Guozhong; Kale, Rahul P.; Lopez, Gabriel P.; Lu, Yunfeng; Prabakar, S.

    1999-01-01

    Microporous silica materials with a controlled pore size and a narrow pore size distribution have been prepared by sol-gel processing using an organic-templating approach. Microporous networks were formed by pyrolytic removal of organic ligands (methacryloxypropyl groups) from organic/inorganic hybrid materials synthesized by copolymerization of 3-methacryloxypropylsilane (MPS) and tetraethoxysilane (TEOS). Molecular simulations and experimental measurements were conducted to examine the relationship between the microstructural characteristics of the porous silica (e.g., pore size, total pore volume, and pore connectivity) and the size and amount of organic template ligands added. Adsorption measurements suggest that the final porosity of the microporous silica is due to both primary pores (those present in the hybrid materials prior to pyrolysis) and secondary pores (those created by pyrolytic removal of organic templates). Primary pores were inaccessible to N(sub 2) at 77 K but accessible to CO(sub 2) at 195 K; secondary pores were accessible to both N(sub 2) (at 77 K) and CO(sub 2) (at 195 K) in adsorption measurements. Primary porosity decreases with the amount of organic ligands added because of the enhanced densification of MPS/TEOS hybrid materials as the mole fraction of trifunctional MPS moieties increases. pore volumes measured by nitrogen adsorption experiments at 77 K suggest that the secondary (template-derived) porosity exhibits a percolation behavior as the template concentration is increased. Gas permeation experiments indicate that the secondary pores are approximately 5(angstrom) in diameter, consistent with predictions based on molecular simulations

  1. Silica-supported, single-site titanium catalysts for olefin epoxidation. A molecular precursor strategy for control of catalyst structure.

    Science.gov (United States)

    Jarupatrakorn, Jonggol; Don Tilley, T

    2002-07-17

    A molecular precursor approach involving simple grafting procedures was used to produce site-isolated titanium-supported epoxidation catalysts of high activity and selectivity. The tris(tert-butoxy)siloxy titanium complexes Ti[OSi(O(t)Bu)(3)](4) (TiSi4), ((i)PrO)Ti[OSi(O(t)Bu)(3)](3) (TiSi3), and ((t)BuO)(3)TiOSi(O(t)Bu)(3) (TiSi) react with the hydroxyl groups of amorphous Aerosil, mesoporous MCM-41, and SBA-15 via loss of HO(t)Bu and/or HOSi(O(t)Bu)(3) and introduction of titanium species onto the silica surface. Powder X-ray diffraction, nitrogen adsorption/desorption, infrared, and diffuse reflectance ultraviolet spectroscopies were used to investigate the structures and chemical natures of the surface-bound titanium species. The titanium species exist mainly in isolated, tetrahedral coordination environments. Increasing the number of siloxide ligands in the molecular precursor decreases the amount of titanium that can be introduced this way, but also enhances the catalytic activity and selectivity for the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. In addition, the high surface area mesoporous silicas (MCM-41 and SBA-15) are more effective than amorphous silica as supports for these catalysts. Supporting TiSi3 on the SBA-15 affords highly active cyclohexene epoxidation catalysts (0.25-1.77 wt % Ti loading) that provide turnover frequencies (TOFs) of 500-1500 h(-1) after 1 h (TOFs are reduced by about half after calcination). These results demonstrate that oxygen-rich siloxide complexes of titanium are useful as precursors to supported epoxidation catalysts.

  2. Electronic structure of semiconductor thin films (chalcopyrites) as absorbermaterials for thin film solar cells

    International Nuclear Information System (INIS)

    Lehmann, Carsten

    2007-01-01

    The objective of this work was to determine for the first time the band structure of CuInS 2 . For this purpose a new GSMBE process with TBDS as sulphur precursor was established to prevent the use of elemental sulphur in an UHV system. Additionally to the deposited films a cleave surface was prepared. The samples were characterized in situ by XPS/UPS and LEED. XRD and SEM were used for further ex situ investigations. The band structure was determined by ARUPS using synchrotron light. CuInS(001) and CuInS 2 (112) were deposited on Si and GaAs. The deposition of CuInS 2 on GaAs showed a strong dependence on the existing surface reconstruction. A 2 x 1 reconstruction of GaAs(001) yielded CuInS 2 (001) films featuring terraces. A deposition on 2 x 2 reconstructed GaAs(111)A surfaces led to a facetted CuInS 2 surface. On sulphur-passivated non-reconstructed GaAs(111)B a deposition of chalcopyrite ordered CuInS 2 free of facets was possible. On the surface of Cu-rich CuInS 2 films CuS crystallites formed. This yields ARUPS spectra showing the electronic stucture of CuInS 2 superimposed by non-dispergative states of the polycrystalline CuS segregations. The effective hole masses were derived from the k vertical stroke vertical stroke measurements. Finally the results of this work showed that the use of a (111) substrate leads to domain formation of the deposited CuInS 2 (112) films. Thus ARUPS spectra of such films show a superposition of the band structures along different directions. (orig.)

  3. Ferromagnetism and temperature-dependent electronic structure in metallic films

    International Nuclear Information System (INIS)

    Herrmann, T.

    1999-01-01

    In this work the influence of the reduced translational symmetry on the magnetic properties of thin itinerant-electron films and surfaces is investigated within the strongly correlated Hubbard model. Firstly, the possibility of spontaneous ferromagnetism in the Hubbard model is discussed for the case of systems with full translational symmetry. Different approximation schemes for the solution of the many-body problem of the Hubbard model are introduced and discussed in detail. It is found that it is vital for a reasonable description of spontaneous ferromagnetism to be consistent with exact results concerning the general shape of the single-electron spectral density in the limit of strong Coulomb interaction between the electrons. The temperature dependence of the ferromagnetic solutions is discussed in detail by use of the magnetization curves as well as the spin-dependent quasi particle spectrum. For the investigation of thin films and surfaces the approximation schemes for the bulk system have to be generalized to deal with the reduced translational symmetry. The magnetic behavior of thin Hubbard films is investigated by use of the layer dependent magnetization as a function of temperature as well as the thickness of the film. The Curie-temperature is calculated as a function of the film thickness. Further, the magnetic stability at the surface is discussed in detail. Here it is found that for strong Coulomb interaction the magnetic stability at finite temperatures is reduced at the surface compared to the inner layers. This observation clearly contradicts the well-known Stoner picture of band magnetism and can be explained in terms of general arguments which are based on exact results in the limit of strong Coulomb interaction. The magnetic behavior of the Hubbard films can be analyzed in detail by inspecting the local quasi particle density of states as well as the wave vector dependent spectral density. The electronic structure is found to be strongly spin

  4. Orientationally ordered ridge structures of aluminum films on hydrogen terminated silicon

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Pantleon, Karen

    2006-01-01

    Films of aluminum deposited onto Si(100) substrates show a surface structure of parallel ridges. On films deposited on oxidized silicon substrates the direction of the ridges is arbitrary, but on films deposited on hydrogen-terminated Si(100) the ridges are oriented parallel to the < 110 > direct......Films of aluminum deposited onto Si(100) substrates show a surface structure of parallel ridges. On films deposited on oxidized silicon substrates the direction of the ridges is arbitrary, but on films deposited on hydrogen-terminated Si(100) the ridges are oriented parallel to the ... > directions on the silicon substrate. The ridge structure appears when the film thickness is above 500 nm, and increasing the film thickness makes the structure more distinct. Anodic oxidation enhances the structure even further. X-ray diffraction indicates that grains in the film have mostly (110) facets...

  5. A proton-exchange membrane prepared by the radiation grafting of styrene and silica into polytetrafluoroethylene films

    Science.gov (United States)

    Yu, Hongyan; Shi, Jianheng; Zeng, Xinmiao; Bao, Mao; Zhao, Xinqing

    2009-07-01

    A polytetrafluoroethylene (PTFE) based organic-inorganic hybrid proton-exchange membrane was prepared from simultaneous radiation grafting of styrene (St) into porous PTFE membrane with the in situ sol-gel reaction of tetraethoxysilane (TEOS) followed by sulfonation in fuming sulfonic acid. The effect of radiation on the sol-gel reaction was studied. The results show that radiation promotes the sol-gel reaction with the help of St at room temperature. Incorporated silica gel helps to produce higher degree of grafting (DOG). SEM analysis was conducted to confirm that the inorganic silicon oxide was introduced to produce hybrid membrane in this work. The proton conductivity of membrane evaluated using electrochemical impedance spectroscopy is much higher (14.3×10 -2 S cm -1) than that of Nafion ® 117 at temperature of 80 °C with acceptable water uptake 51 wt%.

  6. Uniform Pore Structure of Mesoporous Silica Microspheres by Using Di(2-ethylhexyl)phosphoric Acid

    International Nuclear Information System (INIS)

    Kim, Jong Yun; Yoon, Suk Bon; Park, Yong Joon; Jee, Kwang Yong

    2007-01-01

    Spherical morphology has been quite attractive in many special applications, such as display materials offering higher packing densities and lower light scattering for better performances in terms of both brightness and resolution, biosensors utilizing microspheres as an ideal dielectric cavities with high quality factors in optical domain, and standard reference particles for nuclear track analysis utilizing their simple well-defined geometry. There are tremendously a wide variety of studies focused on colloidal spheres of 1 nm - 1,000 nm in diameter although the colloidal dimension can be extended further to 100 μm. Some reports have described the sol-gel surfactant template synthesis of mesoporous silica spheres larger than 100 μm. It is necessary for us to prepare the intermediate 10 - 100 μm-sized silica microspheres for the single particle manipulation by using optical microscope, rather than electron microscope, in a microanalytical technique such as thermal ionization mass spectrometry, secondary ionization mass spectrometry, and laser ionization mass spectrometry

  7. Estimation of structural film viscosity based on the bubble rise method in a nanofluid.

    Science.gov (United States)

    Cho, Heon Ki; Nikolov, Alex D; Wasan, Darsh T

    2018-04-15

    When a single bubble moves at a very low capillary number (10 -7 ) through a liquid with dispersed nanoparticles (nanofluid) inside a vertical tube/capillary, a film is formed between the bubble surface and the tube wall and the nanoparticles self-layer inside the confined film. We measured the film thickness using reflected light interferometry. We calculated the film structural energy isotherm vs. the film thickness from the film-meniscus contact angle measurements using the reflected light interferometric method. Based on the experimental measurement of the film thickness and the calculated values of the film structural energy barrier, we estimated the structural film viscosity vs. the film thickness using the Frenkel approach. Because of the nanoparticle film self-layering phenomenon, we observed a gradual increase in the film viscosity with the decreasing film thickness. However, we observed a significant increase in the film viscosity accompanied by a step-wise decrease in the bubble velocity when the film thickness decreased from 3 to 2 particle layers due to the structural transition in the film. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Silica-Coated Liposomes for Insulin Delivery

    Directory of Open Access Journals (Sweden)

    Neelam Dwivedi

    2010-01-01

    Full Text Available Liposomes coated with silica were explored as protein delivery vehicles for their enhanced stability and improved encapsulation efficiency. Insulin was encapsulated within the fluidic phosphatidylcholine lipid vesicles by thin film hydration at pH 2.5, and layer of silica was formed above lipid bilayer by acid catalysis. The presence of silica coating and encapsulated insulin was identified using confocal and electron microscopy. The native state of insulin present in the formulation was evident from Confocal Micro-Raman spectroscopy. Silica coat enhances the stability of insulin-loaded delivery vehicles. In vivo study shows that these silica coated formulations were biologically active in reducing glucose levels.

  9. Modification of medium-range order in silica glass by ball-milling: real- and reciprocal-space structural correlations for the first sharp diffraction peak

    International Nuclear Information System (INIS)

    Mukai, Akira; Kohara, Shinji; Uchino, Takashi

    2007-01-01

    We have carried out high-energy x-ray diffraction measurements on mechanically milled silica glass. It has been found that the first sharp diffraction peak (FSDP) in the structure factor S(Q) of silica glass appreciably decreases in intensity as a result of mechanical milling, whereas the observed features of the other peaks in S(Q) almost remain unchanged. The corresponding real-space correlation function of the milled samples shows a marked decrease in intensity at r∼5 A. This gives an experimental manifestation that the dominant real-space structural correlation pertaining to the FSDP occurs at r∼5 A

  10. Modification of medium-range order in silica glass by ball-milling: real- and reciprocal-space structural correlations for the first sharp diffraction peak

    Energy Technology Data Exchange (ETDEWEB)

    Mukai, Akira [Department of Chemistry, Kobe University, Kobe 657-8501 (Japan); Kohara, Shinji [SPring-8, Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198 (Japan); Uchino, Takashi [Department of Chemistry, Kobe University, Kobe 657-8501 (Japan)

    2007-11-14

    We have carried out high-energy x-ray diffraction measurements on mechanically milled silica glass. It has been found that the first sharp diffraction peak (FSDP) in the structure factor S(Q) of silica glass appreciably decreases in intensity as a result of mechanical milling, whereas the observed features of the other peaks in S(Q) almost remain unchanged. The corresponding real-space correlation function of the milled samples shows a marked decrease in intensity at r{approx}5 A. This gives an experimental manifestation that the dominant real-space structural correlation pertaining to the FSDP occurs at r{approx}5 A.

  11. Structure and magnetization of Co4N thin film

    Science.gov (United States)

    Pandey, Nidhi; Gupta, Mukul; Gupta, Rachana; Rajput, Parasmani; Stahn, Jochen

    2018-02-01

    In this work, we studied the local structure and the magnetization of Co4N thin films deposited by a reactive dc magnetron sputtering process. The interstitial incorporation of N atoms in a fcc Co lattice is expected to expand the structure. This expansion yields interesting magnetic properties e.g. a larger magnetic moment (than Co) and a very high value of spin polarization ratio in Co4N . By optimizing the growth conditions, we prepared Co4N film having lattice parameter close to its theoretically predicted value. The N concentration was measured using secondary ion mass spectroscopy. Detailed magnetization measurements using bulk magnetization method and polarized neutron reflectivity confirm that the magnetic moment of Co in Co4N is higher than that of Co.

  12. The development of flow-through bio-catalyst microreactors from silica micro structured fibers for lipid transformations.

    Science.gov (United States)

    Anuar, Sabiqah Tuan; Villegas, Carla; Mugo, Samuel M; Curtis, Jonathan M

    2011-06-01

    This study demonstrates the utility of a flow-through enzyme immobilized silica microreactor for lipid transformations. A silica micro structured fiber (MSF) consisting of 168 channels of internal diameter 4-5 μm provided a large surface area for the covalent immobilization of Candida antartica lipase. The specific activity of the immobilized lipase was determined by hydrolysis of p-nitrophenyl butyrate and calculated to be 0.81 U/mg. The catalytic performance of the lipase microreactor was demonstrated by the efficient ethanolysis of canola oil. The parameters affecting the performance of the MSF microreactor, including temperature and reaction flow rate, were investigated. Characterization of the lipid products exiting the microreactor was performed by non-aqueous reversed-phased liquid chromatography (NARP-LC) with evaporative light scattering detector (ELSD) and by comprehensive two-dimensional gas chromatography (GC x GC). Under optimized conditions of 1 μL/min flow rate of 5 mg/mL trioleoylglycerol (TO) in ethanol and 50 °C reaction temperature, 2-monooleoylglycerol was the main product at > 90% reaction yield. The regioselectivity of the Candida antartica lipase immobilized MSF microreactor in the presence of ethanol was found to be comparable to that obtained under conventional conditions. The ability of these reusable flow-through microreactors to regioselectively form monoacylglycerides in high yield from triacylglycerides demonstrate their potential use in small-scale lipid transformations or analytical lipids profiling.

  13. An improved model for estimating fractal structure of silica nano-agglomerates in a vibro-fluidized bed

    Directory of Open Access Journals (Sweden)

    A Esmailpour

    2016-10-01

    Full Text Available A study has been conducted to determine the effects of operating conditions such as vibration frequency, vibration amplitude on the fractal structure of silica (SiO2 nanoparticle agglomerate in a vibro-fluidized bed. An improved model was proposed by assimilation of fractal theory, Richardson-Zaki equation and mass balance. This model has been developed to predict the properties of nanoparticle agglomerate, such as fractal dimension and its size. It has been found out the vibration intensity increase leads to a slight reduction in fractal dimension of agglomerate. This Paper is also indicated that the size of agglomerate has the same behavior as fractal dimension with respect to vibration intensity changes. This study demonstrated that the fractal dimension of Silica nanoparticle agglomerate is in the range of 2.61 to 2.69 and the number of primary particles in the agglomerate is in the order of 1010. The vibration frequency is more impressive than its amplitude on agglomerate size reduction. Calculated Minimum fluidization velocity by applying predicted agglomerate sizes and experimental data are acceptable fitted.

  14. Neutron diffraction studies of thin film multilayer structures

    International Nuclear Information System (INIS)

    Majkrzak, C.F.

    1985-01-01

    The application of neutron diffraction methods to the study of the microscopic chemical and magnetic structures of thin film multilayers is reviewed. Multilayer diffraction phenomena are described in general and in particular for the case in which one of the materials of a bilayer is ferromagnetic and the neutron beam polarized. Recent neutron diffraction measurements performed on some interesting multilayer systems are discussed. 70 refs., 5 figs

  15. Electron confinement in thin metal films. Structure, morphology and interactions

    Energy Technology Data Exchange (ETDEWEB)

    Dil, J.H.

    2006-05-15

    This thesis investigates the interplay between reduced dimensionality, electronic structure, and interface effects in ultrathin metal layers (Pb, In, Al) on a variety of substrates (Si, Cu, graphite). These layers can be grown with such a perfection that electron confinement in the direction normal to the film leads to the occurrence of quantum well states in their valence bands. These quantum well states are studied in detail, and their behaviour with film thickness, on different substrates, and other parameters of growth are used here to characterise a variety of physical properties of such nanoscale systems. The sections of the thesis deal with a determination of quantum well state energies for a large data set on different systems, the interplay between film morphology and electronic structure, and the influence of substrate electronic structure on their band shape; finally, new ground is broken by demonstrating electron localization and correlation effects, and the possibility to measure the influence of electron-phonon coupling in bulk bands. (orig.)

  16. Dendritic silica nanomaterials (KCC-1) with fibrous pore structure possess high DNA adsorption capacity and effectively deliver genes in vitro.

    Science.gov (United States)

    Huang, Xiaoxi; Tao, Zhimin; Praskavich, John C; Goswami, Anandarup; Al-Sharab, Jafar F; Minko, Tamara; Polshettiwar, Vivek; Asefa, Tewodros

    2014-09-16

    The pore size and pore structure of nanoporous materials can affect the materials' physical properties, as well as potential applications in different areas, including catalysis, drug delivery, and biomolecular therapeutics. KCC-1, one of the newest members of silica nanomaterials, possesses fibrous, large pore, dendritic pore networks with wide pore entrances, large pore size distribution, spacious pore volume and large surface area--structural features that are conducive for adsorption and release of large guest molecules and biomacromolecules (e.g., proteins and DNAs). Here, we report the results of our comparative studies of adsorption of salmon DNA in a series of KCC-1-based nanomaterials that are functionalized with different organoamine groups on different parts of their surfaces (channel walls, external surfaces or both). For comparison the results of our studies of adsorption of salmon DNA in similarly functionalized, MCM-41 mesoporous silica nanomaterials with cylindrical pores, some of the most studied silica nanomaterials for drug/gene delivery, are also included. Our results indicate that, despite their relatively lower specific surface area, the KCC-1-based nanomaterials show high adsorption capacity for DNA than the corresponding MCM-41-based nanomaterials, most likely because of KCC-1's large pores, wide pore mouths, fibrous pore network, and thereby more accessible and amenable structure for DNA molecules to diffuse through. Conversely, the MCM-41-based nanomaterials adsorb much less DNA, presumably because their outer surfaces/cylindrical channel pore entrances can get blocked by the DNA molecules, making the inner parts of the materials inaccessible. Moreover, experiments involving fluorescent dye-tagged DNAs suggest that the amine-grafted KCC-1 materials are better suited for delivering the DNAs adsorbed on their surfaces into cellular environments than their MCM-41 counterparts. Finally, cellular toxicity tests show that the KCC-1-based

  17. Structural and magentic characterization of rare earth and transition metal films grown on epitaxial buffer films on semiconductor substrates

    International Nuclear Information System (INIS)

    Farrow, R.F.C.; Parkin, S.S.P.; Speriosu, V.S.; Bezinge, A.; Segmuller, A.P.

    1989-01-01

    Structural and magnetic data are presented and discussed for epitaxial films of rare earth metals (Dy, Ho, Er) on LaF 3 films on the GaAs(TTT) surface and Fe on Ag films on the GaAs(001) surface. Both systems exhibit unusual structural characteristics which influence the magnetic properties of the metal films. In the case of rare earth epitaxy on LaF 3 the authors present evidence for epitaxy across an incommensurate or discommensurate interface. Coherency strain is not transmitted into the metal which behaves much like bulk crystals of the rare earths. In the case of Fe films, tilted epitaxy and long-range coherency strain are confirmed by X- ray diffractometry. Methods of controlling some of these structural effects by modifying the epitaxial structures are presented

  18. Research on structure and electrical parameters of indium antimonide films

    International Nuclear Information System (INIS)

    Mukhametniyazova, A.; Konyaeva, V.F.; Sukhanov, S.; Ashirov, A.; Aleksanyan, S.N.

    1980-01-01

    Results of investigations into the effect of conditions of formation of indium antimonide films prepared by thermal vacuum spraying on their structure, phase composition and electric parameters, are presented. The method of studying the synthesized semiconductor layers on the DRON-0.5 X-ray device with CoKsub(α)-radiation is tested. The dependence of structure, phase composition and electric properties of InSb layers 1+3 μm thick sprayed on ferrite substrates on condensation temperature, is established. Hexagonal InSb modification is found

  19. Research on structure and electrical parameters of indium antimonide films

    Energy Technology Data Exchange (ETDEWEB)

    Mukhametniyazova, A; Konyaeva, V F; Sukhanov, S; Ashirov, A; Aleksanyan, S N [AN Turkmenskoj SSR, Ashkhabad. Fiziko-Tekhnicheskii Inst.

    1980-01-01

    Results of investigations into the effect of conditions of formation of indium antimonide films prepared by thermal vacuum spraying on their structure, phase composition and electric parameters, are presented. The method of studying the synthesized semiconductor layers on the DRON-0.5 X-ray device with CoKsub(..cap alpha..)-radiation is tested. The dependence of structure, phase composition and electric properties of InSb layers 1+3 ..mu..m thick sprayed on ferrite substrates on condensation temperature, is established. Hexagonal InSb modification is found.

  20. Effect of silica-based fillers on structure and properties of epoxy-based composites; Efeito das cargas a base de silica na estrutura e propriedades de compositos a base de resina epoxidica

    Energy Technology Data Exchange (ETDEWEB)

    Solymossy, Ana Paula F.; Dahmouche, Karim; Soares, Bluma G. [Instituto de Macromoleculas (IMA), Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Rocha, L. Alonso; Ribeiro, Sidney J.L, E-mail: apfiuza@ima.ufrj.br [Instituto de Quimica, Universidade Estadual Paulista (UNESP), Araraquara-SP (Brazil)

    2011-07-01

    In the present work, the incorporation effect of nanoparticles of commercial silica (Aerosil R200 - R200), polysilsesquioxane (POSS) and in-situ synthesized mesoporous silica (MP) on the structure, curing and thermal properties of epoxy resin. SAXS analysis of R200 and MP composites showed a tendency to Guinier plateau, while the POSS composite showed larger particle size. By the rheological analysis it was possible to measure the gel time of the composites, of which the greater value obtained was for MP, followed by POSS and then by R200, due to their affinity with the matrix and particle sizes. DMA showed that R200 composite has the lowest modulus, when compared with the other composites. The MP composite has higher Tg than POSS composite and lower than R200 composite. (author)

  1. Krypton adsorption technique for assessment of structural properties of mesoporous silica and titania thin films

    Czech Academy of Sciences Publication Activity Database

    Bartels, O.; Zukal, Arnošt

    2005-01-01

    Roč. 40, 9-10 (2005), s. 2603-2605 ISSN 0022-2461 R&D Projects: GA ČR(CZ) GA203/03/0824 Institutional research plan: CEZ:AV0Z40400503 Keywords : pore-size distribution * Kr adsorption * nitrogen adsorption Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.901, year: 2005

  2. Crack width monitoring of concrete structures based on smart film

    International Nuclear Information System (INIS)

    Zhang, Benniu; Wang, Shuliang; Li, Xingxing; Zhang, Xu; Yang, Guang; Qiu, Minfeng

    2014-01-01

    Due to its direct link to structural security, crack width is thought to be one of the most important parameters reflecting damage conditions of concrete structures. However, the width problem is difficult to solve with the existing structural health monitoring methods. In this paper, crack width monitoring by means of adhering enameled copper wires with different ultimate strains on the surface of structures is proposed, based on smart film crack monitoring put forward by the present authors. The basic idea of the proposed method is related to a proportional relationship between the crack width and ultimate strain of the broken wire. Namely, when a certain width of crack passes through the wire, some low ultimate strain wires will be broken and higher ultimate strain wires may stay non-broken until the crack extends to a larger scale. Detection of the copper wire condition as broken or non-broken may indicate the width of the structural crack. Thereafter, a multi-layered stress transfer model and specimen experiment are performed to quantify the relationship. A practical smart film is then redesigned with this idea and applied to Chongqing Jiangjin Yangtze River Bridge. (paper)

  3. Crack width monitoring of concrete structures based on smart film

    Science.gov (United States)

    Zhang, Benniu; Wang, Shuliang; Li, Xingxing; Zhang, Xu; Yang, Guang; Qiu, Minfeng

    2014-04-01

    Due to its direct link to structural security, crack width is thought to be one of the most important parameters reflecting damage conditions of concrete structures. However, the width problem is difficult to solve with the existing structural health monitoring methods. In this paper, crack width monitoring by means of adhering enameled copper wires with different ultimate strains on the surface of structures is proposed, based on smart film crack monitoring put forward by the present authors. The basic idea of the proposed method is related to a proportional relationship between the crack width and ultimate strain of the broken wire. Namely, when a certain width of crack passes through the wire, some low ultimate strain wires will be broken and higher ultimate strain wires may stay non-broken until the crack extends to a larger scale. Detection of the copper wire condition as broken or non-broken may indicate the width of the structural crack. Thereafter, a multi-layered stress transfer model and specimen experiment are performed to quantify the relationship. A practical smart film is then redesigned with this idea and applied to Chongqing Jiangjin Yangtze River Bridge.

  4. Simultaneous chemical modification and structural transformation of Stöber silica spheres for integration of nanocatalysts

    KAUST Repository

    Yao, Kexin

    2012-01-10

    A synthetic approach has been devised to convert conventional Stöber silica (SiO 2) spheres into a new type of porous structural platform for supporting multicomponent catalysts. With this approach, we have first prepared zinc-doped SiO 2 (Zn-SiO 2) hollow spheres, on which zinc oxide (ZnO) phase and ruthenium (Ru) nanoparticles have been deposited and assembled sequentially in solution phase. A series of complex Ru/ZnO/Zn-SiO 2 nanocatalysts has been thus been integrated onto the zinc-doped SiO 2 supports after additional thermal treatment and reduction. To test their workability under harsh reactive environments, we have further evaluated the above prepared catalysts using arene hydrogenation as model reactions. These integrated nanocatalysts have shown superior activity, high robustness, and easy recovery in the studied heterogeneous catalysis. © 2011 American Chemical Society.

  5. Silica sacrificial layer-assisted in-plane incorporation of Au nanoparticles into mesoporous titania thin films through different reduction methods.

    Science.gov (United States)

    Liang, Chih-Peng; Yamauchi, Yusuke; Liu, Chia-Hung; Wu, Kevin C-W

    2013-06-28

    This study focuses on the incorporation of gold nanoparticles (Au NPs) into our previously synthesized mesoporous titania thin films consisting of titania nanopillars and inverse mesospace (C. W. Wu, T. Ohsuna, M. Kuwabara and K. Kuroda, J. Am. Chem. Soc., 2006, 128, 4544-4545, denoted as MTTFs). Recently, mesoporous titania materials doped with noble metals such as gold have attracted considerable attention because noble metals can enhance the efficiency of mesoporous titania-based devices. In this research, we attempted to use four different reduction methods (i.e., thermal treatment, photo irradiation, liquid immersion, and vapor contacting) to introduce gold nanoparticles (Au NPs) into MTTFs. The synthesized Au@MTTFs were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We further systematically investigated the formation mechanism of gold nanoparticles on the external and internal surfaces of the MTTFs. With the assistance of a silica sacrificial layer, well-dispersed Au NPs with sizes of 4.1 nm were obtained inside the MTTF by photo irradiation. The synthesized Au@MTTF materials show great potential in various photo-electronic and photo-catalytic applications.

  6. On the formation mechanisms of the diffuse atmospheric pressure dielectric barrier discharge in CVD processes of thin silica-like films

    Energy Technology Data Exchange (ETDEWEB)

    Starostin, S A; Premkumar, P Antony [Materials Innovation Institute (M2i), Mekelweg 2, 2600 GA Delft, The Netherland (Netherlands); Creatore, M; Van Veldhuizen, E M; Van de Sanden, M C M [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); De Vries, H; Paffen, R M J [FUJIFILM Manufacturing Europe B.V, PO Box 90156, Tilburg (Netherlands)

    2009-11-15

    Pathways of formation and temporal evolution of the diffuse dielectric barrier discharge at atmospheric pressure were experimentally studied in this work by means of optical (fast imaging camera) and electrical diagnostics. The chosen model system is relevant for applications of plasma-enhanced chemical vapor deposition of thin silica-like film on the polymeric substrate, from cost-efficient gas mixtures of Ar/N{sub 2}/O{sub 2}/hexamethyldisiloxane. It was found that the discharge can gradually experience the phases of homogeneous low current Townsend-like mode, local Townsend to glow transition and expanding high current density ({approx}0.7 A cm{sup -2}) glow-like mode. While the glow-like current spot occupies momentarily only a small part of the electrode area, its expanding behavior provides uniform treatment of the whole substrate surface. Alternatively, it was observed that a visually uniform discharge can be formed by the numerous microdischarges overlapping over the large electrode area.

  7. Effect of alkali–silica reaction on the shear strength of reinforced concrete structural members. A numerical and statistical study

    Energy Technology Data Exchange (ETDEWEB)

    Saouma, Victor E.; Hariri-Ardebili, Mohammad Amin [Department of Civil Engineering, University of Colorado, Boulder, CO 80305 (United States); Le Pape, Yann, E-mail: lepapeym@ornl.gov [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831 (United States); Balaji, Rajagopalan [Department of Civil Engineering, University of Colorado, Boulder, CO 80305 (United States)

    2016-12-15

    Highlights: • Alkali–silica reaction (ASR) affects reinforced structures shear strength. • Statistical analysis indicates large scattering of post-ASR strength losses/gains. • Competitive structural and materials mechanisms affect the residual shear strength. - Abstract: The residual structural shear resistance of concrete members without shear reinforcement and subject to alkali–aggregate reaction (ASR) is investigated by finite element analysis. A parametric numerical study of 648 analyses considering various structural members’ geometries, boundary conditions, ASR-induced losses of materials properties, ASR expansions and reinforcement ratios is conducted. As a result of competitive mechanisms (e.g., ASR-induced prestressing caused by the longitudinal reinforcement) and loss of concrete materials properties, important scatter in terms of gain or loss of shear strength is observed: about 50% of the studied configurations lead to a degradation of structural performance. The range of variation in terms of post-ASR shear resistance is extremely scattered, in particular, when ASR results in out-of-plane expansion only. Influencing factors are derived by two methods: (i) visual inspection of boxplots and probability distributions, and (ii) information criteria within multiple-linear regression analysis.

  8. Materials science in microelectronics I the relationships between thin film processing and structure

    CERN Document Server

    Machlin, Eugene

    2005-01-01

    Thin films play a key role in the material science of microelectronics, and the subject matter of thin-films divides naturally into two headings: processing / structure relationship, and structure / properties relationship.The first volume of Materials Science in Microelectronics focuses on the first relationship - that between processing and the structure of the thin-film. The state of the thin film's surface during the period that one monolayer exists - before being buried in the next layer - determines the ultimate structure of the thin film, and thus its properties. This

  9. Hydration effects on the molecular structure of silica-supported vanadium oxide catalysts: A combined IR, Raman, UV–vis and EXAFS study

    NARCIS (Netherlands)

    Keller, D.E.; Visser, T.; Soulimani, F.; Koningsberger, D.C.; Weckhuysen, B.M.

    2007-01-01

    The effect of hydration on the molecular structure of silica-supported vanadium oxide catalysts with loadings of 1–16 wt.% V has been systematically investigated by infrared, Raman, UV–vis and EXAFS spectroscopy. IR and Raman spectra recorded during hydration revealed the formation of V–OH groups,

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  11. Silica Nephropathy

    Directory of Open Access Journals (Sweden)

    N Ghahramani

    2010-06-01

    Full Text Available Occupational exposure to heavy metals, organic solvents and silica is associated with a variety of renal manifestations. Improved understanding of occupational renal disease provides insight into environmental renal disease, improving knowledge of disease pathogenesis. Silica (SiO2 is an abundant mineral found in sand, rock, and soil. Workers exposed to silica include sandblasters, miners, quarry workers, masons, ceramic workers and glass manufacturers. New cases of silicosis per year have been estimated in the US to be 3600–7300. Exposure to silica has been associated with tubulointerstitial disease, immune-mediated multisystem disease, chronic kidney disease and end-stage renal disease. A rare syndrome of painful, nodular skin lesions has been described in dialysis patients with excessive levels of silicon. Balkan endemic nephropathy is postulated to be due to chronic intoxication with drinking water polluted by silicates released during soil erosion. The mechanism of silica nephrotoxicity is thought to be through direct nephrotoxicity, as well as silica-induced autoimmune diseases such as scleroderma and systemic lupus erythematosus. The renal histopathology varies from focal to crescentic and necrotizing glomerulonephritis with aneurysm formation suggestive of polyarteritis nodosa. The treatment for silica nephrotoxicity is non-specific and depends on the mechanism and stage of the disease. It is quite clear that further research is needed, particularly to elucidate the pathogenesis of silica nephropathy. Considering the importance of diagnosing exposure-related renal disease at early stages, it is imperative to obtain a thorough occupational history in all patients with renal disease, with particular emphasis on exposure to silica, heavy metals, and solvents.

  12. Modification of C60/C70+Pd film structure under electric field influence during electron emission

    International Nuclear Information System (INIS)

    Czerwosz, E.; Dluzewski, P.; Kozlowski, M.

    2001-01-01

    We investigated the modification of structure of C 60 /C 70 +Pd films during cold electron emission from these films. Films were obtained by vacuum thermal deposition from two sources and were characterised before and after electron emission measurements by transmission electron microscopy and electron diffraction. Films were composed of nanocrystalline Pd objects dispersed in carbon/fullerenes matrix. I-V characteristics for electron emission were obtained in diode geometry with additionally applied voltage along the film surface. The modification of film structure occurred under applied electric field and the grouping of Pd nano crystals into bigger objects was observed

  13. Structural study of TiO2-based transparent conducting films

    International Nuclear Information System (INIS)

    Hitosugi, T.; Yamada, N.; Nakao, S.; Hatabayashi, K.; Shimada, T.; Hasegawa, T.

    2008-01-01

    We have investigated microscopic structures of sputter and pulsed laser deposited (PLD) anatase Nb-doped TiO 2 transparent conducting films, and discuss what causes the degradation of resistivity in sputter-deposited films. Cross-sectional transmission electron microscope and polarized optical microscope images show inhomogeneous intragrain structures and small grains of ∼10 μm in sputter-deposited films. From comparison with PLD films, these results suggest that homogeneous film growth is the important factor to obtain highly conducting sputter-deposited film

  14. Benefits of Silica Core-Shell Structures on the Temperature Sensing Properties of Er,Yb:GdVO4 Up-Conversion Nanoparticles.

    Science.gov (United States)

    Savchuk, Oleksandr A; Carvajal, Joan J; Cascales, C; Aguiló, M; Díaz, F

    2016-03-23

    We studied the temperature-dependent luminescence of GdVO4 nanoparticles co-doped with Er(3+) (1 mol %) and Yb(3+) (20 mol %) and determined their thermal sensing properties through the fluorescence intensity ratio (FIR) technique. We also analyzed how a silica coating, in a core-shell structure, affects the temperature sensing properties of this material. Spectra were recorded in the range of biological temperatures (298-343 K). The absolute sensitivity for temperature determination calculated for the core-shell nanoparticles is double the one calculated for bare nanoparticles, achieving a thermal resolution of 0.4 K. Moreover, silica-coated nanoparticles show good dispersibility in different solvents, such as water, DMSO, and methanol. Also, they show good luminescence stability without interactions with solvent molecules. Furthermore, we also observed that the silica coating shell prevents progressive heating of the nanoparticles during prolonged excitation periods with the 980 nm laser, preventing effects on their thermometric applications.

  15. Silica-Coated Liposomes for Insulin Delivery

    OpenAIRE

    Neelam Dwivedi; M. A. Arunagirinathan; Somesh Sharma; Jayesh Bellare

    2010-01-01

    Liposomes coated with silica were explored as protein delivery vehicles for their enhanced stability and improved encapsulation efficiency. Insulin was encapsulated within the fluidic phosphatidylcholine lipid vesicles by thin film hydration at pH 2.5, and layer of silica was formed above lipid bilayer by acid catalysis. The presence of silica coating and encapsulated insulin was identified using confocal and electron microscopy. The native state of insulin present in the formulation was evid...

  16. Partial hydrogenation of alkynes on highly selective nano-structured mesoporous silica MCM-41 composite catalyst

    International Nuclear Information System (INIS)

    Kojoori, R.K.

    2016-01-01

    In this research, we have developed a silica MCM-41/Metformin/Pd (II) nano composite catalyst for the selective hydrogenation of alkynes to the corresponding (Z)-alkenes under a mild condition of atmospheric pressure and room temperature. Firstly, functionalized Si-MCM-41 metformin catalyst with the optimum performance was prepared. Then, the synthesized catalyst was elucidated by X-ray powder diffraction, BET surface area, FT-IR spectrophotometer, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) and applied in partial hydrogenation of different alkynes, with high selectivity and high yield. The products were characterized by 1H-NMR, 13C-NMR, FT-IR, and Mass Spectrometry (MS) that strongly approved the (Z)-double bond configuration of produced alkenes. This prepared catalyst is competitive with the best palladium catalysts known for the selective liquid phase hydrogenation of alkynes and can be easily recovered and regenerated with keeping high activity and selectivity over at least three cycles with a simple regeneration procedure. (author)

  17. Alkali-silica reactivity of expanded glass granules in structure of lightweight concrete

    International Nuclear Information System (INIS)

    Bumanis, G; Bajare, D; Korjakins, A; Locs, J

    2013-01-01

    Main component in the lightweight concrete, which provides its properties, is aggregate. A lot of investigations on alkali silica reaction (ASR) between cement and lightweight aggregates have been done with their results published in the academic literature. Whereas expanded glass granules, which is relatively new product in the market of building materials, has not been a frequent research object. Therefore lightweight granules made from waste glass and eight types of cement with different chemical and mineralogical composition were examined in this research. Expanded glass granules used in this research is commercially available material produced by Penostek. Lightweight concrete mixtures were prepared by using commercial chemical additives to improve workability of concrete. The aim of the study is to identify effect of cement composition to the ASR reaction which occurs between expanded glass granules and binder. Expanded glass granules mechanical and physical properties were determined. In addition, properties of fresh and hardened concrete were determined. The ASR test was processed according to RILEM AAR-2 testing recommendation. Tests with scanning electron microscope and microstructural investigations were performed for expanded glass granules and hardened concrete specimens before and after exposing them in alkali solution

  18. Hydrothermal stability of microporous silica and niobia-silica membranes

    NARCIS (Netherlands)

    Boffa, V.; Blank, David H.A.; ten Elshof, Johan E.

    2008-01-01

    The hydrothermal stability of microporous niobia–silica membranes was investigated and compared with silica membranes. The membranes were exposed to hydrothermal conditions at 150 and 200 °C for 70 h. The change of pore structure before and after exposure to steam was probed by single-gas permeation

  19. Femtosecond laser surface structuring of molybdenum thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kotsedi, L., E-mail: Kotsedi@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Mthunzi, P. [Council for Scientific and Industrial Research (CSIR), Biophotonics Lab: National Laser Centre Pretoria, 0001 (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70/3, 20133 Milano, Itala (Italy); Sechoghela, P.; Mongwaketsi, N. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Ramponi, R. [Institute for Photonics and Nanotechnologies (IFN)–CNR, Piazza Leanardo Da Vinci, 32, 20133 Milano (Italy); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa)

    2015-10-30

    Highlights: • Color change of the molybdenum thin film from shinny to violet–yellowish color after laser irradiation at various laser powers. • Formation of the molybdenum dioxide coating after laser exposure, as confirmed by the X-ray diffraction spectrometry. • Selective solar absorbing nature of the laser exposed films. • Study of the binding energies is presented in this contribution using the XPS spectrometry. - Abstract: This contribution reports on the femtosecond surface structuring of molybdenum thin coatings deposited by electron beam evaporation onto Corning glass substrates. The 1-D type periodic grating lines created by such an ablation showed that the widths of the shallow grooves followed a logarithmic dependence with the laser energy incident on the molybdenum film. The electronic valence “x” of the created oxide surface layer MoO{sub x} was found to be incident laser power dependent via Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy and X-ray diffraction investigations. Such a photo-induced MoO{sub x}–Mo nanocomposite exhibited effective selective solar absorption in the UV–vis–IR spectral range.

  20. Structure and sorption properties of CNC reinforced PVA films.

    Science.gov (United States)

    Popescu, Maria-Cristina

    2017-08-01

    Bio-nanocomposite films based on cellulose nanocrystals reinforced poly(vinyl alcohol) were obtained by solvent casting method. To assess the structural features of the films, different spectral techniques (FTIR, 2D COS and XRD) have been used. Infrared and 2D correlation spectroscopy evidenced the presence of H-bond interactions between the PVA and CNC, and the variation in the conformational rearrangements, while XRD showed that the crystallite size and the crystallinity degree were affected by the incorporation of CNC. At low content of CNC in the PVA matrix, the crystallinity degree decreased to 29.9%, while at higher CNC content increased to 80.6%, comparing to PVA (35.4%). To evaluate the interaction with water, contact angle measurement, water sorption and NIR spectroscopy were used, respectively. The increase of the CNC content induced a reduction in water sorption ability from 93% for PVA to 75% for PVA/CNC films, indicating the involvement of the hydroxyl groups in new hydrogen bonded interactions. By analyzing the variation of the NIR bands from 1930, 1902 and 1985nm, was observed that the water molecules interact with the polymer matrix through moderate hydrogen bond before diffusing into the free volume of the matrix and form stronger hydrogen bonds. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Columnar structure of reactively sputtered aluminium nitride films

    International Nuclear Information System (INIS)

    Chen Chisan; Hwang Binghwai; Lu Hongyang; Hsu Tzuchien

    2002-01-01

    Columnar structure of thin aluminium nitride (AlN) films is examined by x-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The films were deposited on SiO 2 /Si(100) substrate using radiofrequency reactive sputtering method. Strong [0001] preferred orientation is observed by XRD and confirmed by selected area diffraction pattern of TEM. Columnar grains of ∼50-100 nm inclined at an angle of ∼10 deg. to the substrate normal are observed by SEM. As revealed by TEM, each columnar grain is composed of nano-grains of the order of 10 nm and no faceting is observed in the nano-grains and columns. The [0001] preferred orientation results as columnar grains are oriented at various azimuthal angles with their c-axes perpendicular to the substrate surface. A slight tilt of a few tenths of a degree between adjacent nano-grains within a column is also observed. The random azimuthal orientation of columnar grains and small tilt between nano-grains in the films are accommodated by the amorphous phase present in the grain boundaries

  2. Participatory role of zinc in structural and functional characterization of bioremediase: a unique thermostable microbial silica leaching protein.

    Science.gov (United States)

    Chowdhury, Trinath; Sarkar, Manas; Chaudhuri, Biswadeep; Chattopadhyay, Brajadulal; Halder, Umesh Chandra

    2015-07-01

    A unique protein, bioremediase (UniProt Knowledgebase Accession No.: P86277), isolated from a hot spring bacterium BKH1 (GenBank Accession No.: FJ177512), has shown to exhibit silica leaching activity when incorporated to prepare bio-concrete material. Matrix-assisted laser desorption ionization mass spectrometry analysis suggests that bioremediase is 78% homologous to bovine carbonic anhydrase II though it does not exhibit carbonic anhydrase-like activity. Bioinformatics study is performed for understanding the various physical and chemical parameters of the protein which predicts the involvement of zinc encircled by three histidine residues (His94, His96 and His119) at the active site of the protein. Isothermal titration calorimetric-based thermodynamic study on diethyl pyrocarbonate-modified protein recognizes the presence of Zn(2+) in the enzyme moiety. Exothermic to endothermic transition as observed during titration of the protein with Zn(2+) discloses that there are at least two binding sites for zinc within the protein moiety. Addition of Zn(2+) regains the activity of EDTA chelated bioremediase confirming the presence of extra binding site of Zn(2+) in the protein moiety. Revival of folding pattern of completely unfolded urea-treated protein by Zn(2+) explains the participatory role of zinc in structural stability of the protein. Restoration of the λ max in intrinsic fluorescence emission study of the urea-treated protein by Zn(2+) similarly confirms the involvement of Zn in the refolding of the protein. The utility of bioremediase for silica nanoparticles preparation is observed by field emission scanning electron microscopy.

  3. A study of mortars prepared with fly ash and silica fume for use in structures exposed to marine enviroments

    Directory of Open Access Journals (Sweden)

    Hernández, Y.

    2003-12-01

    Full Text Available The purpose of this study is to evaluate different mortar mixtures containing 5, 10 and 1 5% P/P silica fume and 5, 10, 12.5, 15 and 17.5% P/P fly ash to be used for repairing/constructing reinforced concrete structures exposed to marine environments. These were evaluated from the following standpoints: physical-chemical (capillary absorption and effective porosity; mechanical (compressive strength; electrochemical (lineal polarization, cyclic polarización and rapid chloride permeation; morphological (scanning electron microscopy. Results showed that 15 % silica fume mixture with no fly ash gave the best performance from both the physical-mechanical as well as the economic standpoint.

    El presente trabajo tiene como finalidad evaluar diferentes mezclas de mortero con contenidos de 5, 10 y 15 % P/P de microsílica y contenidos de 5, 10, 12,5, 15 y 17,5 % P/P de ceniza volante para ser utilizadas en la reparación/construcción de estructuras de concreto armado expuestas a ambientes marinos. Se evaluaron desde el punto de vista físico-químico (absorción capilar y porosidad efectiva, mecánico (resistencia a la compresión, electroquímico (polarización lineal, polarización cíclica y permeabilidad rápida de cloruros y su morfología por medio de microscopía electrónica de barrido. Los resultados permitieron seleccionar la mezcla conteniendo 15 % de microsílica sin ceniza volante, tanto desde el punto de vista físico-mecánico y electroquímico como económico.

  4. Homogenization models for thin rigid structured surfaces and films.

    Science.gov (United States)

    Marigo, Jean-Jacques; Maurel, Agnès

    2016-07-01

    A homogenization method for thin microstructured surfaces and films is presented. In both cases, sound hard materials are considered, associated with Neumann boundary conditions and the wave equation in the time domain is examined. For a structured surface, a boundary condition is obtained on an equivalent flat wall, which links the acoustic velocity to its normal and tangential derivatives (of the Myers type). For a structured film, jump conditions are obtained for the acoustic pressure and the normal velocity across an equivalent interface (of the Ventcels type). This interface homogenization is based on a matched asymptotic expansion technique, and differs slightly from the classical homogenization, which is known to fail for small structuration thicknesses. In order to get insight into what causes this failure, a two-step homogenization is proposed, mixing classical homogenization and matched asymptotic expansion. Results of the two homogenizations are analyzed in light of the associated elementary problems, which correspond to problems of fluid mechanics, namely, potential flows around rigid obstacles.

  5. Antimicrobial Carvacrol-Containing Polypropylene Films: Composition, Structure and Function

    Directory of Open Access Journals (Sweden)

    Max Krepker

    2018-01-01

    Full Text Available Significant research has been directed toward the incorporation of bioactive plant extracts or essential oils (EOs into polymers to endow the latter with antimicrobial functionality. EOs offer a unique combination of having broad antimicrobial activity from a natural source, generally recognized as safe (GRAS recognition in the US, and a volatile nature. However, their volatility also presents a major challenge in their incorporation into polymers by conventional high-temperature-processing techniques. Herein, antimicrobial polypropylene (PP cast films were produced by incorporating carvacrol (a model EO or carvacrol, loaded into halloysite nanotubes (HNTs, via melt compounding. We studied the composition-structure-property relationships in these systems, focusing on the effect of carvacrol on the composition of the films, the PP crystalline phase and its morphology and the films’ mechanical and antimicrobial properties. For the first time, molecular dynamics simulations were applied to reveal the complex interactions between the components of these carvacrol-containing systems. We show that strong molecular interactions between PP and carvacrol minimize the loss of this highly-volatile EO during high-temperature polymer processing, enabling semi-industrial scale production. The resulting films exhibit outstanding antimicrobial properties against model microorganisms (Escherichia coli and Alternaria alternata. The PP/(HNTs-carvacrol nanocomposite films, containing the carvacrol-loaded HNTs, display a higher level of crystalline order, superior mechanical properties and prolonged release of carvacrol, in comparison to PP/carvacrol blends. These properties are ascribed to the role of HNTs in these nanocomposites and their effect on the PP matrix and retained carvacrol content.

  6. Structure study of the tri-continuous mesoporous silica IBN-9 by electron crystallography

    KAUST Repository

    Zhang, Daliang; Sun, Junliang; Han, Yu; Zou, Xiaodong

    2011-01-01

    High resolution electron microscopy (HRTEM) has unique advantages for structural determination of nano-sized porous materials compared to X-ray diffraction, because it provides the important structure factor phase information which is lost

  7. Structure and photoluminescence of films composed of carbon nanoflakes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi, E-mail: wangyi@cqut.edu.cn [College of Mechanical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054, P R China (China); Li, Lin [College of Chemistry, Chongqing Normal University, Chongqing 401331, P R China (China); Cheng, Qijin [School of Energy Research, Xiamen University, Xiamen 361005, P R China (China); He, Chunlin [Liaoning Provincial Key Laboratory of Advanced Materials, Shenyang University, Shenyang 110044, P R China (China)

    2015-05-15

    Carbon nanoflake films (CNFFs) were directly synthesized by plasma-enhanced hot filament chemical vapor deposition. The results of field emission scanning electron microscope, transmission electron microscope, micro-Raman spectroscope, X-ray photoelectron spectroscope and Fourier transform infrared spectroscope indicate that the CNFFs are composed of bending carbon nanoflakes with the hydrocarbon and hydroxyl functional groups, and the carbon nanoflakes become thin in a long deposition time. The structural change of carbon nanoflakes is related to the formation of structural units and the aggregation of hydrocarbon radicals near the carbon nanoflakes. Moreover, the photoluminescence (PL) properties of CNFFs were studied in a Ramalog system and a PL spectroscope. The PL results indicate that the PL intensity of CNFFs is lowered with the increase of thickness of CNFFs. The lowering of PL intensity for the thick CNFFs originates from the effect of more dangling bonds in the CNFFs. In addition, we studied the structural difference of carbon nanoflakes grown by different CVD systems and the PL difference of carbon nanoflakes in different measurement systems. The results achieved here are important to control the growth and structure of graphene-based materials and fabricate the optoelectronic devices related to carbon-based materials. - Highlights: • Carbon nanoflake films (CNFFs) were synthesized by PEHFCVD. • The structure of CNFFs is related to the aggregation of carbon hydrocarbon radicals. • The PL intensity of CNFFs is lowered with the thickness increase of CNFFs. • The change of PL intensity of CNFFs is due to the dangling bonds in CNFFs. • The widening of PL bands of CNFFs results from the diversity of carbon nanofalkes.

  8. Structural and Electromagnetic Properties of Ni-Mn-Ga Thin Films Deposited on Si Substrates

    Directory of Open Access Journals (Sweden)

    Pereira M. J.

    2014-07-01

    Full Text Available Ni2MnGa thin films raise great interest due to their properties, which provide them with strong potential for technological applications. Ni2MnGa thin films were prepared by r.f. sputtering deposition on Si substrates at low temperature (400 ºC. Film thicknesses in the range 10-120 nm were obtained. A study of the structural, magnetic and electrical properties of the films is presented. We find that the deposited films show some degree of crystallinity, with coexisting cubic and tetragonal structural phases, the first one being preponderant over the latter, particularly in the thinner films. The films possess soft magnetic properties and their coercivity is thickness dependent in the range 15-200 Oe at 300K. Electrical resistivity measurements signal the structural transition and suggest the occurrence of avalanche and return-point memory effects, in temperature cycling through the magnetic/structural transition range.

  9. The effect of film thickness and molecular structure on order and disorder in thin films of compositionally asymmetric block copolymers

    Science.gov (United States)

    Mishra, Vindhya

    Directed self-assembly of thin film block copolymers offer a high throughput-low cost route to produce next generation lithographic devices, if one can bring the defect densities in the self assembled patterns below tolerance limits. However, the ability to control the nanoscale structure or morphology in thin film block copolymers presents challenges due to confinement effects on equilibrium behavior. Using structure characterization techniques such as grazing incidence small angle X-ray scattering (GISAXS), transmission electron and atomic force microscopy as well as self-consistent field theory, we have investigated how film thickness, annealing temperature and block copolymer structure affects the equilibrium behavior of asymmetric block copolymer films. Our studies have revealed the complicated dependence of order-disorder transitions, order-order transitions and symmetry transitions on film thickness. We found that the thickness dependent transition in the packing symmetry of spherical morphology diblock copolymers can be suppressed by blending with a small amount of majority block homopolymer, which allowed us to resolve the driving force behind this transition. Defect densities in, and the order-disorder transition temperature of, thin films of graphoepitaxially aligned diblock copolymer cylinders showed surprising sensitivity to the microdomain spacing. Methods to mitigate defect formation in thin films have been identified. The challenge of quantification of structural order in these systems was overcome using GISAXS, which allowed us to study the phenomena of disordering in two and three dimensions. Through studies on block copolymers which exhibit an order-order transition in bulk, we found that that subtle differences in the packing frustration of the spherical and cylindrical phases as well as the higher configurational entropy of free chain ends at the surface can drive the equilibrium configuration in thin films away from the stable bulk structure

  10. The effects of film thickness on the electrical, optical, and structural properties of cylindrical, rotating, magnetron-sputtered ITO films

    Science.gov (United States)

    Kim, Jae-Ho; Seong, Tae-Yeon; Ahn, Kyung-Jun; Chung, Kwun-Bum; Seok, Hae-Jun; Seo, Hyeong-Jin; Kim, Han-Ki

    2018-05-01

    We report the characteristics of Sn-doped In2O3 (ITO) films intended for use as transparent conducting electrodes; the films were prepared via a five-generation, in-line type, cylindrical, rotating magnetron sputtering (CRMS) system as a function of film thickness. By using a rotating cylindrical ITO target with high usage (∼80%), we prepared high conductivity, transparent ITO films on five-generation size glass. The effects of film thickness on the electrical, optical, morphological, and structural properties of CRMS-grown ITO films are investigated in detail to correlate the thickness and performance of ITO films. The preferred orientation changed from the (2 2 2) to the (4 0 0) plane with increasing thickness of ITO is attributed to the stability of the (4 0 0) plane against resputtering during the CRMS process. Based on X-ray diffraction, surface field emission scanning electron microscopy, and cross-sectional transmission electron microscopy, we suggest a possible mechanism to explain the preferred orientation and effects of film thickness on the performance of CRMS-grown ITO films.

  11. The ionic conductivity, mechanical performance and morphology of two-phase structural electrolytes based on polyethylene glycol, epoxy resin and nano-silica

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Qihang; Yang, Jiping, E-mail: jyang08@163.com; Yu, Yalin; Tian, Fangyu; Zhang, Boming; Feng, Mengjie; Wang, Shubin

    2017-05-15

    Highlights: • Structural electrolytes based on PEG-epoxy resins were prepared. • Factors of influencing ionic conductivity and mechanical properties were studied. • Co-continuous morphology was benefit for improved structural electrolyte property. • Efficiently optimized multifunctional electrolyte performance was achieved. - Abstract: As one of significant parts of structural power composites, structural electrolytes have desirable mechanical properties like structural resins while integrating enough ionic conductivity to work as electrolytes. Here, a series of polyethylene glycol (PEG)-epoxy-based electrolytes filled with nano-silica were prepared. The ionic conductivity and mechanical performance were studied as functions of PEG content, lithium salt concentration, nano-silica content and different curing agents. It was found that, PEG-600 and PEG-2000 content in the epoxy electrolyte system had a significant effect on their ionic conductivity. Furthermore, increasing the nano-silica content in the system induced increased ionic conductivity, decreased glass transition temperature and mechanical properties, and more interconnected irregular network in the cured systems. The introduction of rigid m-xylylenediamine resulted in enhanced mechanical properties and reasonably decreased ionic conductivity. As a result, these two-phase epoxy structural electrolytes have great potential to be used in the multifunctional energy storage devices.

  12. Composite Films Formed by Cellulose nanocrystals and Latex Nanoparticles: Optical, Structural, and Mechanical Properties

    Science.gov (United States)

    Vollick, Brandon McRae

    This thesis describes the preparation of iridescent, birefringent, composite films composed of cellulose nanocrystals (CNCs), latex nanoparticles (NPs) and a NP crosslinker; hexanediamine (HDA). First, aqueous suspensions were prepared with varying quantities of CNCs, NPs and HDA before equilibrating for one week. The cholesteric (Ch) phase was then cast and dried into a film. The optical, structural and mechanical properties of the film was analyzed. Second, films with identical compositions of CNCs, NPs, and HDA were fabricated in three different ways to yield films of different morphology, (i) fast drying of an isotropic suspension, yielding an isotropic film, (ii) slow drying of an isotropic suspension, yielding a partially Ch films, (iii) slow drying of an equilibrated suspension, yielding a highly Ch film. The optical and mechanical properties of the films was analyzed.

  13. Effect of sputtering power on structure and properties of Bi film deposited by DC magnetron sputtering

    International Nuclear Information System (INIS)

    Liao Guo; He Zhibing; Xu Hua; Li Jun; Chen Taihua; Chen Jiajun

    2012-01-01

    Bi film was fabricated at different sputtering powers by DC magnetron sputtering. The deposition rate of Bi film as the function of sputtering power was studied. The surface topography of Bi film was observed by SEM, and the growth mode of Bi film was investigated. The crystal structure was analyzed by XRD. The grain size and stress of Bi film were calculated. The SEM images show that all the films are columnar growth. The average grain size firstly increases as the sputtering power increases, then decreases at 60 W. The film becomes loose with the increase of sputtering power, while, the film gets compact when the sputtering power becomes from 45 to 60 W. The XRD results show that films are polycrystalline of hexagonal. And the stress transforms from the tensile stress to compressive stress as the sputtering power increases. (authors)

  14. Stable single longitudinal mode erbium-doped silica fiber laser based on an asymmetric linear three-cavity structure

    International Nuclear Information System (INIS)

    Feng Ting; Yan Feng-Ping; Li Qi; Peng Wan-Jing; Feng Su-Chun; Tan Si-Yu; Wen Xiao-Dong

    2013-01-01

    We present a stable linear-cavity single longitudinal mode (SLM) erbium-doped silica fiber laser. It consists of four fiber Bragg gratings (FBGs) directly written in a section of photosensitive erbium-doped fiber (EDF) to form an asymmetric three-cavity structure. The stable SLM operation at a wavelength of 1545.112 nm with a 3-dB bandwidth of 0.012 nm and an optical signal-to-noise ratio (OSNR) of about 60 dB is verified experimentally. Under laboratory conditions, the performance of a power fluctuation of less than 0.05 dB observed from the power meter for 6 h and a wavelength variation of less than 0.01 nm obtained from the optical spectrum analyzer (OSA) for about 1.5 h are demonstrated. The gain fiber length is no longer limited to only several centimeters for SLM operation because of the excellent mode-selecting ability of the asymmetric three-cavity structure. The proposed scheme provides a simple and cost-effective approach to realizing a stable SLM fiber laser. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  15. Optical and structural properties of FeSe2 thin films obtained by selenization of sprayed amorphous iron oxide films

    International Nuclear Information System (INIS)

    Ouertani, B.; Ouerfelli, J.; Saadoun, M.; Zribi, M.; Rabha, M.Ben; Bessais, B.; Ezzaouia, H.

    2006-01-01

    We report in this work the optical and structural properties of iron diselenide films (FeSe 2 ) obtained by selenization under vacuum of amorphous iron oxide films predeposited by spray pyrolysis. The structure of the FeSe 2 films was investigated by scanning electron microscopy (SEM), microprobe analyses, atomic force microscopy (AFM) and X-ray diffraction (XRD). XRD and micro-probe analyses showed that FeSe 2 as well as FeSe 2-x phases begin to appear at a selenization temperature of 500 deg. C. As the selenization temperature rises, the iron diselenide films become more stoichiometric with a dominance of the FeSe 2 phase. At 550 deg. C, a single FeSe 2 phase having good crystallinity was obtained. At 600 deg. C, two phases were detected: the major one corresponds to Fe 3 O 4 , and the minor one to FeSe 2 . SEM surface views show that FeSe 2 films have granular structure with small spherical crystallites. However, layered and clustered FeSe 2 films were found, respectively, at 550 deg. C and 600 deg. C. Absorption measurements show that iron diselenide films have a direct and an indirect gaps of about 1.03 eV and 0.3 eV, which were suggested to be due to the stoichiometric FeSe 2 phase and to a Fe-rich non-stoichiometric phase, respectively

  16. Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy and ultra-small angle X-ray scattering experiments

    CERN Document Server

    Marliere, C; Etienne, P; Woignier, T; Dieudonné, P; Phalippou, J

    2001-01-01

    During the last few years the bulk structure of silica aerogels has been extensively studied mainly by scattering techniques (neutrons, X-rays, light). It has been shown that small silica particles aggregate to constitute a fractal network. Its spatial extension and fractal dimension are strongly dependent on the synthesis conditions (e.g., pH of gelifying solutions). These typical lengths range from 1 to 10 nm. Ultra-small angle X-ray scattering (USAXS) and atomic force microscopy (AFM) experiments have been carried out on aerogels at different steps of densification. The results presented in this paper reveal the existence of a spatial arrangement of the solid part at a very large length scale. The evolution of this very large-scale structure during the densification process has been studied and reveals a contraction of this macro-structure made of aggregates of clusters. (16 refs).

  17. The Influence of Kinetic Structure in Films on Biology Students' Achievement and Attitude.

    Science.gov (United States)

    Simmons, Ellen Stephanie

    1980-01-01

    Tested and supported was the hypothesis that students receiving high-structured film narrations will acquire more knowledge and will respond more favorably than those receiving low-structured film narrations. Results contribute additional data to evidence supporting the need for critical application of the kinetic structure theory in evaluating…

  18. Investigation of structure, adhesion strength, wear performance and corrosion behavior of platinum/ruthenium/nitrogen doped diamond-like carbon thin films with respect to film thickness

    International Nuclear Information System (INIS)

    Khun, N.W.; Liu, E.

    2011-01-01

    Research highlights: → Sputtered PtRuN-DLC thin films were fabricated with different film thicknesses. → The graphitization of the films increased with increased film thickness. → The wear resistance of the films increased though their adhesion strength decreased. → The corrosion potentials of the films shifted to more negative values. → However, the corrosion currents of the films decreased. - Abstract: In this study, the corrosion performance of platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films deposited on p-Si substrates using a DC magnetron sputtering deposition system in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test in terms of film thickness. The effect of the film thickness on the chemical composition, bonding structure, surface morphology, adhesion strength and wear resistance of the PtRuN-DLC films was studied using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), micro-scratch test and ball-on-disc tribotest, respectively. It was found that the wear resistance of the PtRuN-DLC films apparently increased with increased film thickness though the adhesion strength of the films decreased. The corrosion results revealed that the increased concentration of sp 2 bonds in the PtRuN-DLC films with increased film thickness shifted the corrosion potentials of the films to more negative values but the decreased porosity density in the films significantly decreased the corrosion currents of the films.

  19. Structure and density for As23Se67Ge10 amorphous films

    International Nuclear Information System (INIS)

    Shchurova, T.N.; Savchenko, N.D.

    1999-01-01

    The effect of thermal annealing and argon laser irradiation on structure and volume for thin amorphous As 23 Se 67 Ge 10 films deposited by thermal evaporation has been investigated. The short-range structure for the annealed films has been found to be more ordered as compared to the irradiated films. The decrease in film volume under thermal annealing and its increase under laser irradiation have been shown. The changes in film volume have been discussed in the context of non-ergodic model for the amorphous state equilibrium taking into account forces acting from the substrate

  20. Structural transformation of CsI thin film photocathodes under exposure to air and UV irradiation

    CERN Document Server

    Tremsin, A S; Siegmund, O H W

    2000-01-01

    Transmission electron microscopy has been employed to study the structure of polycrystalline CsI thin films and its transformation under exposure to humid air and UV irradiation. The catastrophic degradation of CsI thin film photocathode performance is shown to be associated with the film dissolving followed by its re-crystallization. This results in the formation of large lumps of CsI crystal on the substrate surface, so that the film becomes discontinuous and its performance as a photocathode is permanently degraded. No change in the surface morphology and the film crystalline structure was observed after the samples were UV irradiated.

  1. A density functional theory study of the structure of pure-silica and aluminium-substituted MFI nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Tamargo, Carlos E.; Roldan, Alberto [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT (United Kingdom); Leeuw, Nora H. de, E-mail: deleeuwn@cardiff.ac.uk [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT (United Kingdom)

    2016-05-15

    The layered MFI zeolite allows a straightforward hierarchization of the pore system which accelerates mass transfer and increases its lifetime as a catalyst. Here, we present a theoretical study of the structural features of the pure-silica and aluminium-substituted MFI nanosheets. We have analysed the effects of aluminium substitution on the vibrational properties of silanols as well as the features of protons as counter-ions. The formation of the two-dimensional system did not lead to appreciable distortions within the framework. Moreover, the effects on the structure due to the aluminium dopants were the same in both the bulk and the slab. The principal differences were related to the silanol groups that form hydrogen-bonds with neighbouring aluminium-substituted silanols, whereas intra-framework hydrogen-bonds increase the stability of aluminium-substituted silanols toward dehydration. Thus, we have complemented previous experimental and theoretical studies, showing the lamellar MFI zeolite to be a very stable material of high crystallinity regardless of its very thin structure. - Graphical abstract: The structure of MFI zeolite nanosheet was investigated using Density Functional Theory. The results showed no differences against the bulk-type material upon aluminium doping. The aluminium-substituted silanol dehydrates toward a more stable configuration composed by a water molecule adsorbed on a Lewis centre. - Highlights: • MFI nanosheets with variable thicknesses were characterised using DFT calculations. • The distortions in the nanosheets after Al substitution reproduced those of the bulk. • H-bonds were only observed between silanol groups when the Al substitution took place. • The kinetic of the Al-silanol dehydration is dependent on intra-framework H-bonds. • Lewis acids with adsorbed water are more stable than Al-silanols. • The proton accessibility was related to the framework O atom binding the proton.

  2. Effect of deposition temperature on the structural, morphological and optical band gap of lead selenide thin films synthesized by chemical bath deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Hone, Fekadu Gashaw, E-mail: fekeye@gmail.com [Hawassa University, Department of Physics, Hawassa (Ethiopia); Ampong, Francis Kofi [Kwame Nkrumah University of Science and Technology, Department of Physics, Kumasi (Ghana)

    2016-11-01

    Lead selenide (PbSe) nanocrystalline thin films have been deposited on silica glass substrates by the chemical bath deposition technique. The samples were deposited at the bath temperatures of 60, 75 and 90 °C respectively and characterized by a variety of techniques. The XRD results revealed that the PbSe thin film deposited at 60 °C was amorphous in nature. Films deposited at higher temperatures exhibited sharp and intense diffraction peaks, indicating an improvement in crystallinety. The deposition temperature also had a strong influence on the preferred orientation of the crystallites as well as other structural parameters such as microstrain and dislocation density. From the SEM study it was observed that film deposited at 90 °C had well defined crystallites, uniformly distributed over the entire surface of the substrate. The EDAX study confirmed that the samples deposited at the higher temperature had a better stoichiometric ratio. The optical band gap varied from 2.26 eV to 1.13 eV with increasing deposition temperature. - Highlights: • The crystallinety of the films improved as the deposition temperature increased. • The deposition temperature strongly influenced the preferred orientations. • Microstrain and dislocation density are decreased linearly with deposition temperature. • Band gap decreased from 2.26 eV to 1.13 eV as the deposition temperature increased.

  3. Stress and stability of sputter deposited A-15 and bcc crystal structure tungsten thin films

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, M.J.; Stutz, C.E.

    1997-07-01

    Magnetron sputter deposition was used to fabricate body centered cubic (bcc) and A-15 crystal structure W thin films. Previous work demonstrated that the as-deposited crystal structure of the films was dependent on the deposition parameters and that the formation of a metastable A-15 structure was favored over the thermodynamically stable bcc phase when the films contained a few atomic percent oxygen. However, the A-15 phase was shown to irreversibly transform into the bcc phase between 500 C and 650 C and that a significant decrease in the resistivity of the metallic films was measured after the transformation. The current investigation of 150 nm thick, sputter deposited A-15 and bcc tungsten thin films on silicon wafers consisted of a series of experiments in which the stress, resistivity and crystal structure of the films was measured as a function of temperatures cycles in a Flexus 2900 thin film stress measurement system. The as-deposited film stress was found to be a function of the sputtering pressure and presputter time; under conditions in which the as-deposited stress of the film was {approximately}1.5 GPa compressive delamination of the W film from the substrate was observed. Data from the thermal studies indicated that bcc film stress was not affected by annealing but transformation of the A-15 structure resulted in a large tensile increase in the stress of the film, regardless of the as-deposited stress of the film. In several instances, complete transformation of the A-15 structure into the bcc phase resulted in {ge}1 GPa tensile increase in film stress.

  4. Stress and stability of sputter deposited A-15 and bcc crystal structure tungsten thin films

    International Nuclear Information System (INIS)

    O'Keefe, M.J.; Stutz, C.E.

    1997-01-01

    Magnetron sputter deposition was used to fabricate body centered cubic (bcc) and A-15 crystal structure W thin films. Previous work demonstrated that the as-deposited crystal structure of the films was dependent on the deposition parameters and that the formation of a metastable A-15 structure was favored over the thermodynamically stable bcc phase when the films contained a few atomic percent oxygen. However, the A-15 phase was shown to irreversibly transform into the bcc phase between 500 C and 650 C and that a significant decrease in the resistivity of the metallic films was measured after the transformation. The current investigation of 150 nm thick, sputter deposited A-15 and bcc tungsten thin films on silicon wafers consisted of a series of experiments in which the stress, resistivity and crystal structure of the films was measured as a function of temperatures cycles in a Flexus 2900 thin film stress measurement system. The as-deposited film stress was found to be a function of the sputtering pressure and presputter time; under conditions in which the as-deposited stress of the film was approximately1.5 GPa compressive delamination of the W film from the substrate was observed. Data from the thermal studies indicated that bcc film stress was not affected by annealing but transformation of the A-15 structure resulted in a large tensile increase in the stress of the film, regardless of the as-deposited stress of the film. In several instances, complete transformation of the A-15 structure into the bcc phase resulted in ge1 GPa tensile increase in film stress

  5. Aspects of the structure of film expression and anthropological paradigm of films reception in Croatian cinema and TV distribution.

    Science.gov (United States)

    Svilicić, Niksa

    2012-09-01

    This research paper deals with one part of a comprehensive study called "Causality of narratological-semiotic aspects of the structure of film expression and paradigms of reception of Croatian feature film". It is conceived as a response to the hypothesis that the expression of narrative-semiotic terms correlate with the reception of the Croatian feature film audience and all them leads into a broader holistic i.e. anthropological context.The basic idea of scientific research is to analyze the complete feature productions since Croatian independence 1991 to date, presented at the National Film Festival (film festival in Pula), identify, define and isolate positive social narrative-semiotic stereotypes, which can then serve as a paradigm of better ratings and increase of the currently very low rating of domestic films in Croatian cinemas, as well as TV distribution. In other words, the paper will be analyzed and processed by a range of different effects based on narrative-semiotic, set design and mise-en-scène motives, used in the Croatian feature films since independence to date, that we assume to positively influence the mood of the viewer, and thus increase the rating of the film.

  6. Fabrication and structural analysis of polyrotaxane fibers and films

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Yasuhiro; Ueda, Kentaro; Yokoyama, Hideaki; Ito, Kohzo [Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwano-ha, Kashiwa, Chiba 277-8561 (Japan); Katsuyama, Naoya; Shimizu, Koji; Sato, Shunya; Kuroiwa, Jun; Teramoto, Akira; Abe, Koji [Faculty of Textile Science and Technology, Shinshu University, Tokida 3-15-1, Ueda, Nagano 386-8567 (Japan); Araki, Jun, E-mail: sakai@molle.k.u-tokyo.ac.jp, E-mail: kohzo@k.u-tokyo.ac.jp [International Young Researchers Empowerment Center, Shinshu University, Tokida 3-15-1, Ueda, Nagano 386-8567 (Japan)

    2011-07-20

    Polyrotaxane (PR), a typical example of topological supramolecular architecture, consists of multiple cyclic molecules threaded onto a linear polymer backbone and capped with bulky end-groups. The PR system of polyethylene glycol and {alpha}-cyclodextrin ({alpha}-CD) has been extensively studied for its facile synthesis, unique molecular structure, and possible applications for various smart materials. We have previously demonstrated the fabrication of PR-based fibers without chemical cross-links by wet spinning of PR solution. In this paper, we investigate the crystal structure of {alpha}-CDs in PR fibers and the effect of drawing on it. The {alpha}-CDs in PR fiber are found to form hexagonal channel-type structure. The drawing process promotes formation of the packing arrangement of {alpha}-CDs in the c-axis because of the sliding of {alpha}-CD molecules along the polymer backbone. In addition, we demonstrate the preparation of an elastomeric PR film having similar network structure to the fibers and ethylene glycol oligomer as plasticizer.

  7. Fabrication and structural analysis of polyrotaxane fibers and films

    International Nuclear Information System (INIS)

    Sakai, Yasuhiro; Ueda, Kentaro; Yokoyama, Hideaki; Ito, Kohzo; Katsuyama, Naoya; Shimizu, Koji; Sato, Shunya; Kuroiwa, Jun; Teramoto, Akira; Abe, Koji; Araki, Jun

    2011-01-01

    Polyrotaxane (PR), a typical example of topological supramolecular architecture, consists of multiple cyclic molecules threaded onto a linear polymer backbone and capped with bulky end-groups. The PR system of polyethylene glycol and α-cyclodextrin (α-CD) has been extensively studied for its facile synthesis, unique molecular structure, and possible applications for various smart materials. We have previously demonstrated the fabrication of PR-based fibers without chemical cross-links by wet spinning of PR solution. In this paper, we investigate the crystal structure of α-CDs in PR fibers and the effect of drawing on it. The α-CDs in PR fiber are found to form hexagonal channel-type structure. The drawing process promotes formation of the packing arrangement of α-CDs in the c-axis because of the sliding of α-CD molecules along the polymer backbone. In addition, we demonstrate the preparation of an elastomeric PR film having similar network structure to the fibers and ethylene glycol oligomer as plasticizer.

  8. Effect of thermal history on the structure of chemically and vapor deposited silver films on glass

    International Nuclear Information System (INIS)

    Shelby, J.E.; Nichols, M.C.; Smith, D.K. Jr.; Vitko, J. Jr.

    1981-01-01

    The observation of silver agglomeration in second surface mirrors used for solar applications has emphasized consideration of the effect of thermal history on the optical properties of mirrors. Thermal history effects may arise from the processing of mirrors, the application of protective coatings, or from outdoor exposure. Mirrors may be subject to elevated temperatures (T less than or equal to 400 0 C) for short periods of time, or to low temperatures (T less than or equal to 60 0 C) for long (less than or equal to 30 years) periods of time. Although a significant amount of work has been done on thermally driven agglomeration of silver films, most of these studies have been restricted to vapor deposited films on vitreous silica. Large area reflectors, such as those used in heliostats, will almost certainly be deposited by commercial chemical methods on substrates of soda-lime-silicate or other glasses which differ considerably from vitreous silica in composition and properties. The present study addresses the effect of this change in deposition technique and substrate on silver agglomeration. These problems were studied by optical and scanning electron microscopy, reflectometry, and x-ray diffraction. The results indicate that both the method used to deposit the silver and the type of glass affect the agglomeration process and the character of the reflective film

  9. Evaluation on an influence to turbine generator installed on a concrete foundation structure affected by alkali-silica reaction

    International Nuclear Information System (INIS)

    Takeo Takakura; Takashi Momoo; Shigeru Harada; Yoshihisa Asai; Takashi Hosokawa

    2005-01-01

    A turbine generator to be evaluated is a one with 566 MW capacity installed on a reinforced concrete supporting structure having a table deck portion where equipments are installed and columns to support on the table deck. After the initial operation of this turbine generator started, a difference from the initial setting at an installation stage was found at turbine generator in the annual inspection on 1979. The turbine generator foundation (herein after TG foundation) had expanded mainly longitudinal direction, and it was confirmed this expansion occurred due to affected by Alkali-Silica reaction (herein after ASR) according to concrete core samples tests. The measurement for TG foundation such as displacements started at this time. On the other hand, bearing metal temperatures and shaft vibration for the turbine generator have been continuously monitored by supervisory from initial operation. No abnormal alarm or trips by extraordinary metal temperature or axle vibration of the turbine generator due to TG foundation expansion affected by ASR have been arisen. However it is required to confirm sounding of this turbine generator in order to safely operation. The purpose of this paper checked and examined allowable capacity of turbine generator and TG foundation, in order to operate continuously and safely. (authors)

  10. Deep-UV Raman spectroscopic analysis of structure and dissolution rates of silica-rich sodium borosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, Charles F.; Pierce, Eric M.; Burton, Sarah D.; Bovaird, Chase C.

    2011-03-24

    As part of ongoing studies to evaluate the relationships between structural variations in silicate glasses and rates of glass dissolution in aqueous media, molecular structures present in sodium borosilicate glasses of composition Na2O.xB2O3.(3-x)SiO2, with x 1 (Na2O/B2O3 ratio 1), were analyzed using deep-UV Raman spectroscopy. The results were quantified in terms of the fraction of SiO4 tetrahedra with one non-bridging oxygen (Q3) and then correlated with Na2O and B2O3 content. Increasing Na2O was found to raise the fraction of Q3 units in the glasses systematically, in agreement with studies on related glasses, and, as long as the value of x was not too high, contribute to higher rates of dissolution in single pass flow-through testing. The finding was obtained across more than one series of silica-rich glasses prepared for independent dissolution studies. In contrast, dissolution rates were less strongly determined by the Q3 fraction when the value of x was near unity and appeared to grow larger upon further reduction of the Q3 fraction. The results were interpreted to indicate the increasingly important role of network hydrolysis in the glass dissolution mechanism as the BO4 tetrahedron replaces the Q3 unit as the charge-compensating structure for Na+ ions. Finally, the use of deep-UV Raman spectroscopy was found to be advantageous in studying finely powdered glasses in cases where visible Raman spectroscopy suffered from weak Raman scattering and fluorescence interference.

  11. Correlation between acoustical and structural properties of glasses: Extension of Abd El-Moneim model for bioactive silica based glasses

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-Moneim, Amin, E-mail: aminabdelmoneim@hotmail.com

    2016-04-15

    Correlation between room temperature ultrasonic attenuation coefficient and the most significant structural parameters has been studied in the bioactive silica based glasses, for the first time. The correlation has been carried out in the quaternary SiO{sub 2}–Na{sub 2}O–CaO–P{sub 2}O{sub 5} glass system using the two semi-empirical formulas, which have been presented recently by the author. Changes in the elastic properties, related to the substitution of SiO{sub 2} by alkali Na{sub 2}O and alkaline earth CaO oxides, have also been deduced by evaluating the mean atomic volume, packing density, fractal bond connectivity and density of the analogous crystalline structure. Furthermore, values of the theoretical elastic moduli have been calculated on the basis of Makishima-Mackenzie theory and compared with the corresponding observed values. Results show that the correlation between ultrasonic attenuation coefficient and the oxygen density, average atomic ring size, first-order stretching force constant and experimental bulk modulus was achieved at 5 MHz frequency. Values of the theoretically calculated shear modulus are in excellent correlation (C. R. ≻95%) with the corresponding experimental ones. The divergence between the theoretical and experimental values of bulk modulus has been discussed. - Highlights: • Abd El-Moneim model was extended for bioactive glasses. • Ultrasonic attenuation was correlated with structural parameters. • Correlation was carried out in Si–Na–Ca–P glasses. • The model is valid for all investigated glass samples. • Agreement between theoretical and experimental elastic moduli was studied.

  12. Structural and optical properties of furfurylidenemalononitrile thin films

    Science.gov (United States)

    Ali, H. A. M.

    2013-03-01

    Thin films of furfurylidenemalononitrile (FMN) were deposited on different substrates at room temperature by thermal evaporation technique under a high vacuum. The structure of the powder was confirmed by Fourier transformation infrared (FTIR) technique. The unit cell dimensions were determined from X-ray diffraction (XRD) studies. The optical properties were investigated using spectrophotometric measurements of the transmittance and reflectance at normal incidence of light in the wavelength range from 200 to 2500 nm. The refractive index (n), the absorption index (k) and the absorption coefficient (α) were calculated. The analysis of the spectral behavior of the absorption coefficient in the absorption region revealed an indirect allowed transition. The refractive index dispersion was analyzed using the single oscillator model. Some dispersion parameters were estimated. Complex dielectric function and optical conductivity were determined. The influence of the irradiation with high-energy X-rays (6 MeV) on the studied properties was also investigated.

  13. Highly stable thin film transistors using multilayer channel structure

    KAUST Repository

    Nayak, Pradipta K.

    2015-03-09

    We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60°C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO2 layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO2 layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

  14. Positron annihilation study of structural subnanovoids and irradiation damages in silica-based glasses

    International Nuclear Information System (INIS)

    Inoue, K.

    2004-01-01

    Structural subnanovoids in glass solidified with radioactive waste disposal were studied by positron annihilation 2-dimensional angular correlation and positron life time measurements. Positroniums in crystalline SiO 2 were in a delocalized state, but in glass SiO 2 were in a localized state. Pick-off annihilation (pair annihilation between an ortho-positroniums and a spin antiparallel electron) rate was shortened with decreasing molarity of glass network formers and consequently radii of structural subnanovoids were reduced. The sizes of structural subnanovoids determined from the pick-off annihilation were good agreement with those measured by momentum distribution of para-positroniums. In waste disposal model glass, no presence of positronims indicated that radioactive substances occupied almost all subnanovoids, and therefore voids with large size enough to localize positroniums (above 0.1 nm radius) could not be present. (Y. Kazumata)

  15. Effects of oxygen partial pressure on structural and gasochromic properties of sputtered VOx thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Wei-Luen [National Synchrotron Radiation Research Center (NSRRC), Hsinchu 30076, Taiwan (China); Lu, Yang-Ming [Department of Electrical Engineering, National University of Tainan, Tainan 70005, Taiwan (China); Lu, Ying-Rui [National Synchrotron Radiation Research Center (NSRRC), Hsinchu 30076, Taiwan (China); Program for Science and Technology of Accelerator Light Source, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Chen, Chi-Liang [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Dong, Chung-Li, E-mail: dong.cl@nsrrc.org.tw [National Synchrotron Radiation Research Center (NSRRC), Hsinchu 30076, Taiwan (China); Chou, Wu-Ching [Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Chen, Jeng-Lung; Chan, Ting-Shan; Lee, Jyh-Fu; Pao, Chih-Wen [National Synchrotron Radiation Research Center (NSRRC), Hsinchu 30076, Taiwan (China); Hwang, Weng-Sing [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2013-10-01

    VOx films were deposited by radio-frequency reactive magnetron sputtering from a vanadium target in an Ar–O{sub 2} gas mixture and pure O{sub 2}. For the films deposited in the gas mixture, the Ar flow rate was controlled at 20 sccm and the oxygen flow rate was controlled at 1, 3, and 5 sccm, respectively. A thin (∼ 5 nm) Pt layer was deposited on the VOx thin films as a hydrogen catalyst. The long-range structural order, short-range atom arrangement, and gasochromic properties of the deposited films were studied. The grazing incidence X-ray diffraction (GIXRD) results indicate that the deposited films are amorphous. Lamellar structures were found at oxygen flow rates of 3 sccm and above. The X-ray absorption spectroscopy (XAS) results show that the short-range atom arrangement of the lamellar VOx thin films is similar to that of crystal V{sub 2}O{sub 5}. The GIXRD and XAS results show that the film obtained with the gas mixture and at an oxygen flow rate of 1 sccm did not significantly change after exposure to hydrogen, whereas the other films exhibited decreased interlayer distance, oxidation state, and crystallinity. The color of the films changed from light or deep yellow to gray. The results suggest that the gasochromic properties of the VOx thin films are related to the V{sub 2}O{sub 5}-like atom arrangement and the interlayer distance of the lamellar structure. The films deposited with an oxygen flow rate of 3 sccm and above can be applied to H{sub 2} gas sensors. - Highlights: • Sputtered VOx film capped by Pt have potential for application in hydrogen sensor. • We present the X-ray absorption spectroscopy study of the gasochromic VOx films. • Correlation of gasochromism and electronic structure of VOx film were studied. • Correlation of gasochromism and atomic structure were investigated.

  16. Effect of crystal structure on optical properties of sol–gel derived zirconia thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaodong, E-mail: xiaodong_wang@tongji.edu.cn [Pohl Institute of Solid State Physics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092 (China); Wu, Guangming; Zhou, Bin [Pohl Institute of Solid State Physics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092 (China); Shen, Jun, E-mail: shenjun67@tongji.edu.cn [Pohl Institute of Solid State Physics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092 (China)

    2013-04-15

    Highlights: ► ZrO{sub 2} films were deposited by sol–gel method. ► Crystal structures of the films were tuned by different thermal annealing methods. ► The refractive indices vary with the crystal structures of the films. ► Lattice-mismatch was found to reduce the refractive index of ZrO{sub 2} films. -- Abstract: The optical properties of sol–gel derived zirconia thin films and their relation to the crystal structure are studied in this paper. ZrO{sub 2} films were deposited on quartz glass and silicon wafer substrates by sol–gel method with conventional furnace annealing (CFA) and rapid thermal annealing (RTA). Crystal structures of the films were analyzed by X-ray diffraction (XRD) and Raman spectroscopy, while refractive indices of the films were determined from the reflectance and transmittance spectra. The refractive indices vary with the function of crystal structure and density of the films, which depends on annealing temperature and annealing technique. Lattice-mismatch between monoclinic phase and tetragonal phase was found to reduce the refractive index of ZrO{sub 2} films.

  17. Structural characterization of vacuum evaporated ZnSe thin films

    Indian Academy of Sciences (India)

    The lattice parameter, grain size, average internal stress, microstrain, dislocation density and degree of pre- ferred orientation in the film are calculated and correlated with Ts. Keywords. ZnSe thin films; X-ray diffraction; average internal stress; microstrain; dislocation density. 1. Introduction. Thin films of ZnSe has attracted ...

  18. Structure of the Buried Metal-Molecule Interface in Organic Thin Film Devices

    DEFF Research Database (Denmark)

    Hansen, Christian Rein; Sørensen, Thomas Just; Glyvradal, Magni

    2009-01-01

    By use of specular X-ray reflectivity (XR) the structure of a metal-covered organic thin film device is measured with angstrom resolution. The model system is a Langmuir-Blodgett (LB) film, sandwiched between a silicon substrate and a top electrode consisting of 25 Å titanium and 100 Å aluminum....... By comparison of XR data for the five-layer Pb2+ arachidate LB film before and after vapor deposition of the Ti/Al top electrode, a detailed account of the structural damage to the organic film at the buried metal-molecule interface is obtained. We find that the organized structure of the two topmost LB layers...

  19. Evaluation of concrete structures affected by alkali-silica reaction and delayed ettringite formation - part 2.

    Science.gov (United States)

    2012-12-01

    This report details the results of a comprehensive research project aimed at evaluating the potential use of : non-destructive testing (NDT) to assess structures affected by ASR and/or DEF. This project was a : collaborative effort between the Univer...

  20. Optical analysis of the fine crystalline structure of artificial opal films.

    Science.gov (United States)

    Lozano, G; Dorado, L A; Schinca, D; Depine, R A; Míguez, H

    2009-11-17

    Herein, we present a detailed analysis of the structure of artificial opal films. We demonstrate that, rather than the generally assumed face centered cubic lattice of spheres, opal films are better approximated by rhombohedral assemblies of distorted colloids. Detailed analysis of the optical response in a very wide spectral range (0.4 opal films is provided, as well as of the photonic band structure of the proposed arrangement. The implications of this distortion in the optical response of the lattice are discussed.

  1. Determination of the Steady State Leakage Current in Structures with Ferroelectric Ceramic Films

    Science.gov (United States)

    Podgornyi, Yu. V.; Vorotilov, K. A.; Sigov, A. S.

    2018-03-01

    Steady state leakage currents have been investigated in capacitor structures with ferroelectric solgel films of lead zirconate titanate (PZT) formed on silicon substrates with a lower Pt electrode. It is established that Pt/PZT/Hg structures, regardless of the PZT film thickness, are characterized by the presence of a rectifying contact similar to p-n junction. The steady state leakage current in the forward direction increases with a decrease in the film thickness and is determined by the ferroelectric bulk conductivity.

  2. The effect of laser irradiation on electrical and structural properties of ZnO thin films

    Directory of Open Access Journals (Sweden)

    P Kameli

    2013-03-01

    Full Text Available  In this paper, ZnO thin film was prepared by sol-gel process on glass substrates. The deposited films were dried at 100 and 240 ˚C and then annealed at 300, 400 and 500 ˚C. The two-probe measurement showed that resistance of as-prepared films is very high. The KrF excimer (λ=248 nm laser irradiation with 1000 pulses, frequency of 1 Hz and 90 mJ/cm2 energy on surface of film resulted in the reduction of the films electrical resistance. X-ray diffraction (XRD patterns confirmed the improved hexagonal wurtzite structure of film, and AFM and FE-SEM analyses showed regular and spherical grain was formed on the surface. The particle size was increased from ~10 to ~30 nm after leaser irradiation. Generally, it was showed that electrical, structural and morphological properties of films improve considerably by laser irradiation.

  3. Synthesis and characterization of DC magnetron sputtered nano structured molybdenum thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rondiya, S. R.; Rokade, A. V.; Jadhavar, A. A.; Pandharkar, S. M.; Kulkarni, R. R.; Karpe, S. D.; Diwate, K. D. [School of Energy Studies, Savitribai Phule Pune University, Pune 411007 (India); Jadkar, S. R., E-mail: sandesh@physics.unipune.ac.in [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India)

    2016-04-13

    Molybdenum (Mo) thin films were deposited on corning glass (#7059) substrates using DC magnetron sputtering system. The effect of substrate temperature on the structural, morphology and topological properties have been investigated. Films were characterized by variety of techniques such as low angle x-ray diffraction (low angle XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM). The low angle XRD analysis revealed that the synthesized Mo films are nanocrystalline having cubic crystal structure with (110) preferential orientation. The microstructure of the deposited Mo thin films observed with FE-SEM images indicated that films are homogeneous and uniform with randomly oriented leaf shape morphology. The AFM analysis shows that with increase in substrate temperature the rms roughness of Mo films increases. The obtained results suggest that the synthesized nanostructured Mo thin films have potential application as a back contact material for high efficiency solar cells like CdTe, CIGS, CZTS etc.

  4. Supramolecular structure of a perylene derivative in thin films deposited by physical vapor deposition

    International Nuclear Information System (INIS)

    Fernandes, Jose D.; Aoki, Pedro H.B.; Constantino, Carlos J.J.; Junior, Wagner D.M.; Teixeira, Silvio R.

    2014-01-01

    Full text: Thin films of a perylene derivative, the bis butylimido perylene (BuPTCD), were produced using thermal evaporation (PVD, physical vapor deposition). The main objective is to investigate the supramolecular structure of the BuPTCD in these PVD films, which implies to control the thickness and to determine the molecular organization, morphology at micro and nanometer scales and crystallinity. This supramolecular structure is a key factor in the optical and electrical properties of the film. The ultraviolet-visible absorption revealed an uniform growth of the PVD films. The optical and atomic force microscopy images showed a homogeneous surface of the film at micro and nanometer scales. A preferential orientation of the molecules in the PVD films was determined via infrared absorption. The X-ray diffraction showed that both powder and PVD film are in the crystalline form. (author)

  5. Controlling thin film structure for the dewetting of catalyst nanoparticle arrays for subsequent carbon nanofiber growth

    International Nuclear Information System (INIS)

    Randolph, S J; Fowlkes, J D; Melechko, A V; Klein, K L; III, H M Meyer; Simpson, M L; Rack, P D

    2007-01-01

    Vertically aligned carbon nanofiber (CNF) growth is a catalytic chemical vapor deposition process in which structure and functionality is controlled by the plasma conditions and the properties of the catalyst nanoparticles that template the fiber growth. We have found that the resultant catalyst nanoparticle network that forms by the dewetting of a continuous catalyst thin film is dependent on the initial properties of the thin film. Here we report the ability to tailor the crystallographic texture and composition of the nickel catalyst film and subsequently the nanoparticle template by varying the rf magnetron sputter deposition conditions. After sputtering the Ni catalyst thin films, the films are heated and exposed to an ammonia dc plasma, to chemically reduce the native oxide on the films and induce dewetting of the film to form nanoparticles. Subsequent nanoparticle treatment in an acetylene plasma at high substrate temperature results in CNF growth. Evidence is presented that the texture and composition of the nickel thin film has a significant impact on the structure and composition of the formed nanoparticle, as well as the resultant CNF morphology. Nickel films with a preferred (111) or (100) texture were produced and conditions favoring interfacial silicidation reactions were identified and investigated. Both compositional and structural analysis of the films and nanoparticles indicate that the properties of the as-deposited Ni catalyst film influences the subsequent nanoparticle formation and ultimately the catalytic growth of the carbon nanofibers

  6. Platinum-induced structural collapse in layered oxide polycrystalline films

    International Nuclear Information System (INIS)

    Wang, Jianlin; Liu, Changhui; Huang, Haoliang; Fu, Zhengping; Peng, Ranran; Zhai, Xiaofang; Lu, Yalin

    2015-01-01

    Effect of a platinum bottom electrode on the SrBi 5 Fe 1−x Co x Ti 4 O 18 layered oxide polycrystalline films was systematically studied. The doped cobalt ions react with the platinum to form a secondary phase of PtCoO 2 , which has a typical Delafossite structure with a weak antiferromagnetism and an exceptionally high in-plane electrical conductivity. Formation of PtCoO 2 at the interface partially consumes the cobalt dopant and leads to the structural collapsing from 5 to 4 layers, which was confirmed by X-ray diffraction and high resolution transmission electron microscopy measurements. Considering the weak magnetic contribution from PtCoO 2 , the observed ferromagnetism should be intrinsic of the Aurivillius compounds. Ferroelectric properties were also indicated by the piezoresponse force microscopy. In this work, the platinum induced secondary phase at the interface was observed, which has a strong impact on Aurivillius structural configuration and thus the ferromagnetic and ferroelectric properties

  7. The structure of organic langmuir films on liquid metal surfaces

    International Nuclear Information System (INIS)

    Kraack, H.; Deutsch, M.; Ocko, B.M.; Pershan, P.S.

    2003-01-01

    Langmuir films (LFs) on water have long been studied for their interest for basic science and their numerous applications in chemistry, physics, materials science and biology. We present here A-resolution synchrotron X-ray studies of the structure of stearic acid LFs on a liquid mercury surface. At low coverage, ≥110 A 2 /mol, a 2D gas phase of flat-lying molecules is observed. At high coverage, ≤23 A 2 /mol, two different hexatic phases of standing-up molecules are observed. At intermediate coverage, 52≤A≤110 A 2 /mol, novel single- and double-layered phases of flat-lying molecular dimers are found, exhibiting a 1D in-layer order. Such flat-lying phases were not hitherto observed in any LF. Measurements on LFs of fatty acids of other chain lengths indicate that this structure is generic to chain molecules on mercury, although the existence of some of the flat-lying phases, and the observed phase sequence, depend on the chain length. Organic LFs on Hg, and in particular the new flat-lying phases, should provide a broader nano-structural tunability range for molecular electronic device construction than most solid-supported self-assembled monolayers used at present

  8. Structural, dielectric and ferroelectric characterization of PZT thin films

    Directory of Open Access Journals (Sweden)

    Araújo E.B.

    1999-01-01

    Full Text Available In this work ferroelectric thin films of PZT were prepared by the oxide precursor method, deposited on Pt/Si substrate. Films of 0.5 mm average thickness were obtained. Electrical and ferroelectric characterization were carried out in these films. The measured value of the dielectric constant for films was 455. Ferroelectricity was confirmed by Capacitance-Voltage (C-V characteristics and P-E hysteresis loops. Remanent polarization for films presented value around 5.0 µC/cm2 and a coercive field of 88.8 kV/cm.

  9. Spectral Inverse Quantum (Spectral-IQ Method for Modeling Mesoporous Systems: Application on Silica Films by FTIR

    Directory of Open Access Journals (Sweden)

    Mihai V. Putz

    2012-11-01

    Full Text Available The present work advances the inverse quantum (IQ structural criterion for ordering and characterizing the porosity of the mesosystems based on the recently advanced ratio of the particle-to-wave nature of quantum objects within the extended Heisenberg uncertainty relationship through employing the quantum fluctuation, both for free and observed quantum scattering information, as computed upon spectral identification of the wave-numbers specific to the maximum of absorption intensity record, and to left-, right- and full-width at the half maximum (FWHM of the concerned bands of a given compound. It furnishes the hierarchy for classifying the mesoporous systems from more particle-related (porous, tight or ionic bindings to more wave behavior (free or covalent bindings. This so-called spectral inverse quantum (Spectral-IQ particle-to-wave assignment was illustrated on spectral measurement of FT-IR (bonding bands’ assignment for samples synthesized within different basic environment and different thermal treatment on mesoporous materials obtained by sol-gel technique with n-dodecyl trimethyl ammonium bromide (DTAB and cetyltrimethylammonium bromide (CTAB and of their combination as cosolvents. The results were analyzed in the light of the so-called residual inverse quantum information, accounting for the free binding potency of analyzed samples at drying temperature, and were checked by cross-validation with thermal decomposition techniques by endo-exo thermo correlations at a higher temperature.

  10. Nano-phase separation and structural ordering in silica-rich mixed network former glasses.

    Science.gov (United States)

    Liu, Hao; Youngman, Randall E; Kapoor, Saurabh; Jensen, Lars R; Smedskjaer, Morten M; Yue, Yuanzheng

    2018-06-13

    We investigate the structure, phase separation, glass transition, and crystallization in a mixed network former glass series, i.e., B2O3-Al2O3-SiO2-P2O5 glasses with varying SiO2/B2O3 molar ratio. All the studied glasses exhibit two separate glassy phases: droplet phase (G1) with the size of 50-100 nm and matrix phase (G2), corresponding to a lower calorimetric glass transition temperature (Tg1) and a higher one (Tg2), respectively. Both Tg values decrease linearly with the substitution of B2O3 for SiO2, but the magnitude of the decrease is larger for Tg1. Based on nuclear magnetic resonance and Raman spectroscopy results, we infer that the G1 phase is rich in boroxol rings, while the G2 phase mainly involves the B-O-Si network. Both phases contain BPO4- and AlPO4-like units. Ordered domains occur in G2 upon isothermal and dynamic heating, driven by the structural heterogeneity in the as-prepared glasses. The structural ordering lowers the activation energy of crystal growth, thus promoting partial crystallization of G2. These findings are useful for understanding glass formation and phase separation in mixed network former oxide systems, and for tailoring their properties.

  11. Structure and giant magnetoresistance of carbon-based amorphous films prepared by magnetron sputtering

    International Nuclear Information System (INIS)

    Ma, L.; He, M.F.; Liu, Z.W.; Zeng, D.C.; Gu, Z.F.; Cheng, G.

    2014-01-01

    Pure amorphous carbon (a-C) and Co-doped Co x C 1−x films were prepared on n-Si(100) substrates by dc magnetron sputtering. In Co–C films, the nano-sized amorphous Co particles were homogeneously dispersed in the amorphous cross-linked carbon matrix. The structures of a-C and Co x C 1−x films were investigated by X-ray photoelectron spectroscopy and Raman spectroscopy. The results showed that the a-C films were diamond-like carbon (DLC) films. After doping cobalt into DLC film, the sp 3 -hybridized carbon content in DLC composite films almost had no change. The as-deposited Co x C 1−x granular films had larger value of magnetoresistance (MR) than the amorphous carbon film. A very high positive MR, up to 15.5% at magnetic field B = 0.8 T and x = 2.5 at.% was observed in a Co x C 1−x granular film with thickness of 80 nm at room temperature when the external magnetic field was perpendicular to the electric current and the film surface. With increase of the film thickness and Co-doped content, the MR decreased gradually. It remains a challenge to well explain the observed MR effect in the Co x C 1−x granular films. - Highlights: • The amorphous carbon films were diamond-like carbon films. • No carbide appearing, the Co–C composite films form a good metal/insulator system. • A high positive magnetoresistance, up to 15.5% at B = 0.8 T was observed in Co–C films

  12. Electron irradiation effects on partially fluorinated polymer films: Structure-property relationships

    International Nuclear Information System (INIS)

    Nasef, Mohamed Mahmoud; Dahlan, Khairul Zaman M.

    2003-01-01

    The effects of electron beam irradiation on two partially fluorinated polymer films i.e. poly(vinylidene fluoride) (PVDF) and poly(ethylene-tetrafluoroethylene) copolymer (ETFE) are studied at doses ranging from 100 to 1200 kGy in air at room temperature. Chemical structure, thermal and mechanical properties of irradiated films are investigated. FTIR show that both PVDF and ETFE films undergo similar changes in their chemical structures including the formation of carbonyl groups and double bonding. The changes in melting and crystallisation temperatures (T m and T c ) in both irradiated films are functions of irradiation dose and reflect the disorder in the chemical structure caused by the competition between crosslinking and chain scission. The heat of melting (ΔH m ) and the degree of crystallinity (X c ) of PVDF films show no significant changes with the dose increase, whereas those of ETFE films are reduced rapidly after the first 100 kGy. The tensile strength of PVDF films is improved by irradiation compared to its rapid deterioration in ETFE films, which stemmed from the degradation prompted by the presence of radiation sensitive tetrafluoroethylene (TFE) comonomer units. The elongation at break of both films drops gradually with the dose increase indicating the formation of predominant crosslinked structures at high doses. However, the response of each polymer to crosslinking and main chain scission at various irradiation doses varies from PVDF to ETFE films

  13. Effect of Structure, Composition, and Micromorphology on the Hydrophobic Property of F-DLC Film

    Directory of Open Access Journals (Sweden)

    Aihua Jiang

    2013-01-01

    Full Text Available Fluorinated diamond-like carbon (F-DLC films were prepared by radio frequency plasma-enhanced chemical vapor deposition technique with CF4 and CH4 as source gases under different deposition conditions. The chemical bonding structure and composition of the films were detected by Raman, Fourier transform infrared absorption spectrometry (FTIR, and X-ray photoelectron spectroscopy (XPS characterization. The micromorphology and surface roughness of the film were observed and analyzed by atomic force microscopy (AFM. The results indicated that all the prepared films presented a diamond-like carbon structure. The relative content of fluorine in the films increased, containing more CF2 groups. The ratio of hybrid structure sp3/sp2 decreased. The surface roughness of the films increased when the gas flow ratio R (R = CF4/[CH4 + CF4] or the deposition power increased. The contact angle of water with the surface of the F-DLC film was measured with a static drop-contact angle/surface tension measuring instrument. The hydrophobic property of the F-DLC films was found to be dependent on the sp2 structure, fluorine content, and surface roughness of the films. The contact angle increased when the relative content of fluorine in the films and sp2 content increased, whereas the contact angle first increased and then decreased with the surface roughness.

  14. Systematic investigation of the effects of organic film structure on light emitting diode performance

    Science.gov (United States)

    Joswick, M. D.; Campbell, I. H.; Barashkov, N. N.; Ferraris, J. P.

    1996-09-01

    We present a systematic investigation of the effects of organic film structure on light emitting diode (LED) performance. Metal/organic film/metal LEDs were fabricated using a five ring, poly(phenylene vinylene) related oligomer as the active layer. The structure of the vacuum evaporated oligomer films was varied from amorphous to polycrystalline by changing the substrate temperature during deposition. The intrinsic properties of the oligomer films and the LED performance were measured. The measured intrinsic film properties include: optical absorption, photoluminescence (PL) spectra, PL lifetime, PL efficiency, and effective carrier mobility. The measured device characteristics include current-voltage, capacitance-voltage, electroluminescence (EL) efficiency, and the contact metal/organic film Schottky barrier heights. The optical absorption and PL properties of the films are weakly dependent on film structure but the effective carrier mobility decreases with increasing crystallinity. The EL quantum efficiency decreases by more than one order of magnitude, the drive voltage at a fixed current increases, and the electron Schottky barrier height increases as the crystallinity of the film is increased. The diode current-voltage characteristic is determined by the dominant hole current and the electroluminescence efficiency is controlled by the contact limited electron injection. These results demonstrate significant effects of organic film structure on the performance of organic LEDs.

  15. Systematic investigation of the effects of organic film structure on light emitting diode performance

    Energy Technology Data Exchange (ETDEWEB)

    Joswick, M.D.; Campbell, I.H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Barashkov, N.N.; Ferraris, J.P. [The University of Texas at Dallas, Richardson, Texas 75080 (United States)

    1996-09-01

    We present a systematic investigation of the effects of organic film structure on light emitting diode (LED) performance. Metal/organic film/metal LEDs were fabricated using a five ring, poly(phenylene vinylene) related oligomer as the active layer. The structure of the vacuum evaporated oligomer films was varied from amorphous to polycrystalline by changing the substrate temperature during deposition. The intrinsic properties of the oligomer films and the LED performance were measured. The measured intrinsic film properties include: optical absorption, photoluminescence (PL) spectra, PL lifetime, PL efficiency, and effective carrier mobility. The measured device characteristics include current{endash}voltage, capacitance{endash}voltage, electroluminescence (EL) efficiency, and the contact metal/organic film Schottky barrier heights. The optical absorption and PL properties of the films are weakly dependent on film structure but the effective carrier mobility decreases with increasing crystallinity. The EL quantum efficiency decreases by more than one order of magnitude, the drive voltage at a fixed current increases, and the electron Schottky barrier height increases as the crystallinity of the film is increased. The diode current{endash}voltage characteristic is determined by the dominant hole current and the electroluminescence efficiency is controlled by the contact limited electron injection. These results demonstrate significant effects of organic film structure on the performance of organic LEDs. {copyright} {ital 1996 American Institute of Physics.}

  16. Silicon-integrated thin-film structure for electro-optic applications

    Science.gov (United States)

    McKee, Rodney A.; Walker, Frederick Joseph

    2000-01-01

    A crystalline thin-film structure suited for use in any of an number of electro-optic applications, such as a phase modulator or a component of an interferometer, includes a semiconductor substrate of silicon and a ferroelectric, optically-clear thin film of the perovskite BaTiO.sub.3 overlying the surface of the silicon substrate. The BaTiO.sub.3 thin film is characterized in that substantially all of the dipole moments associated with the ferroelectric film are arranged substantially parallel to the surface of the substrate to enhance the electro-optic qualities of the film.

  17. Structure, electrochromic and optical properties of WO3 film prepared by dip coating-pyrolysis

    International Nuclear Information System (INIS)

    Yang Haitao; Shang Fuliang; Gao Ling; Han Haitao

    2007-01-01

    The tungsten oxide (WO 3 ) film was grown by dip coating-pyrolysis method with the PEG-400 as the structure-directing agent. Microstructure of the WO 3 film was characterized by TG-DSC, XRD and SEM techniques. It was found that the film annealed at 350 deg. C for 2 h comprised cubic WO 3 and orthorhombic WO 3 . The measurements of the cyclic voltammetry (CV) and UV-vis spectrum suggested that the WO 3 film had a good electrochromic reversibility performance. The film possessed excellent modulation to the visible light and the maximal average transmittance modulation reached 70.06%

  18. Study of Nb-oxide Nb-Pb film structures by tunnel scanning microscope

    International Nuclear Information System (INIS)

    Golyamina, E.M.; Troyanovskij, A.M.

    1986-01-01

    The surface of niobium films, which were earlier used to create niobium-niobium oxide-lead film structures on their base, was investigated, using tunnel scanning microscope. The results obtained agree well with the observed properties of these structures, containing josephson and tunnel junctions

  19. Influence of film structure on the dewetting kinetics of thin polymer films in the solvent annealing process.

    Science.gov (United States)

    Zhang, Huanhuan; Xu, Lin; Lai, Yuqing; Shi, Tongfei

    2016-06-28

    On a non-wetting solid substrate, the solvent annealing process of a thin polymer film includes the swelling process and the dewetting process. Owing to difficulties in the in situ analysis of the two processes simultaneously, a quantitative study on the solvent annealing process of thin polymer films on the non-wetting solid substrate is extremely rare. In this paper, we design an experimental method by combining spectroscopic ellipsometry with optical microscopy to achieve the simultaneous in situ study. Using this method, we investigate the influence of the structure of swollen film on its dewetting kinetics during the solvent annealing process. The results show that for a thin PS film with low Mw (Mw = 4.1 kg mol(-1)), acetone molecules can form an ultrathin enriched layer between the PS film and the solid substrate during the swelling process. The presence of the acetone enriched layer accounts for the exponential kinetic behavior in the case of a thin PS film with low Mw. However, the acetone enriched layer is not observed in the case of a thin PS film with high Mw (Mw = 400 kg mol(-1)) and the slippage effect of polymer chains is valid during the dewetting process.

  20. Imaging of current distributions in superconducting thin film structures

    International Nuclear Information System (INIS)

    Doenitz, D.

    2006-01-01

    Local analysis plays an important role in many fields of scientific research. However, imaging methods are not very common in the investigation of superconductors. For more than 20 years, Low Temperature Scanning Electron Microscopy (LTSEM) has been successfully used at the University of Tuebingen for studying of condensed matter phenomena, especially of superconductivity. In this thesis LTSEM was used for imaging current distributions in different superconducting thin film structures: - Imaging of current distributions in Josephson junctions with ferromagnetic interlayer, also known as SIFS junctions, showed inhomogeneous current transport over the junctions which directly led to an improvement in the fabrication process. An investigation of improved samples showed a very homogeneous current distribution without any trace of magnetic domains. Either such domains were not present or too small for imaging with the LTSEM. - An investigation of Nb/YBCO zigzag Josephson junctions yielded important information on signal formation in the LTSEM both for Josephson junctions in the short and in the long limit. Using a reference junction our signal formation model could be verified, thus confirming earlier results on short zigzag junctions. These results, which could be reproduced in this work, support the theory of d-wave symmetry in the superconducting order parameter of YBCO. Furthermore, investigations of the quasiparticle tunneling in the zigzag junctions showed the existence of Andreev bound states, which is another indication of the d-wave symmetry in YBCO. - The LTSEM study of Hot Electron Bolometers (HEB) allowed the first successful imaging of a stable 'Hot Spot', a self-heating region in HEB structures. Moreover, the electron beam was used to induce an - otherwise unstable - hot spot. Both investigations yielded information on the homogeneity of the samples. - An entirely new method of imaging the current distribution in superconducting interference devices

  1. Edge-closed laminated structures for thin-film heads

    Science.gov (United States)

    Herman, D. A.; Argyle, B. E.; Lee, H.-P.; Trouilloud, P. O.; Petek, B.

    1991-04-01

    Magnetic film laminations containing nonmagnetic spacers have been explored with the hope of eliminating domain walls to diminish Barkhausen instabilities. Such laminates have limitations however, which originate in their ``edge-curling walls'' (ECWs).1 We have developed a new structure, free of ECWs, in which flux closure at opposing edges occurs via edge-shorting material added to circulate the easy-axis flux of the flat layers. We show experimentally with Kerr-effect imaging that (1) this edge-closed laminated (ECL) structure can support an (ECW-free) ``easy-axis'' (EA) magnetic state under conditions as modeled recently by Slonczewski,2 and (2) that this EA state is quite robust in the face of imperfect structure fabrication. This is, if the imperfections are not too severe, the resultant states depart minimally from the pure EA state and conduct hard-axis-driven flux nearly as well. Flat-film ECL elements in diamond, stripe, and recording-head-yoke shapes, plus experimental heads with ECL top yokes, were fabricated. Our domain images verify some key predictions from Slonczewski's static equilibrium modeling; additional results taken in applied magnetic fields extend the micromagnetic understanding. The sketch shows a typical domain pattem for a yoke-shaped element. The most stable state in the open portion of the yoke is the single domain shown. This remanent pattern was stable in the face of (slowly varying) external fields up to the 150 Oe that could be applied. The pole tip region contained a few 180° walls as indicated. On close inspection, these walls were seen to end in vestigial, nontouching, closure domains as predicted by the model when only partial flux closure occurs via the edge shorting material. The wall spacing in the tip varied somewhat following saturation-demagnetization cycles. The dynamic stability of this EA state was investigated in the experimental heads having ECL top yokes. The pseudodynamic LAMOM technique3 was applied using ``write

  2. Surfactant adsorption and aggregate structure of silica nanoparticles: a versatile stratagem for the regulation of particle size and surface modification

    International Nuclear Information System (INIS)

    Chaudhary, Savita; Rohilla, Deepak; Mehta, S K

    2014-01-01

    The area of silica nanoparticles is incredibly polygonal. Silica particles have aroused exceptional deliberation in bio-analysis due to great progress in particular arenas, for instance, biocompatibility, unique properties of modifiable pore size and organization, huge facade areas and pore volumes, manageable morphology and amendable surfaces, elevated chemical and thermal stability. Currently, silica nanoparticles participate in crucial utilities in daily trade rationales such as power storage, chemical and genetic sensors, groceries dispensation and catalysis. Herein, the size-dependent interfacial relation of anionic silica nanoparticles with twelve altered categories of cationic surfactants has been carried out in terms of the physical chemical facets of colloid and interface science. The current analysis endeavours to investigate the virtual consequences of different surfactants through the development of the objective composite materials. The nanoparticle size controls, the surface-to-volume ratio and surface bend relating to its interaction with surfactant will also be addressed in this work. More importantly, the simulated stratagem developed in this work can be lengthened to formulate core–shell nanostructures with functional nanoparticles encapsulated in silica particles, making this approach valuable and extensively pertinent for employing sophisticated materials for catalysis and drug delivery. (papers)

  3. Dispersion of nano-silica in monomer casting nylon6 and its effect on the structure and properties of composites

    Directory of Open Access Journals (Sweden)

    2010-07-01

    Full Text Available To promote dispersion of nano-silica in monomer casting nylon6 (MC nylon6, nano-silica was dispersed in melted caprolactam with the assistance of ultrasound, anionic polymerization was then initiated to form silica/MC nylon6 in-situ nanocomposites. It was found that hydrogen bonds were formed between nano-silica and caprolactam, in the meantime, ultrasound helped to break the nanoparticles aggregations into smaller ones or even mono-dispersing particles. Therefore, the agglomerated nanoparticles were pulled apart and stabilized by caprolactam. Additionally, the rapid anionic polymerization of caprolactam also contributed to the avoidance of re-agglomeration and deposition of nanoparticles during the polymerization process, leading to the uniform distribution of nanoparticles in the polymer matrix. Mechanical tests indicated that the silica/MC nylon6 in-situ nanocomposites prepared according to the above strategy were simultaneously toughened, strengthened and stiffened. Thermogravimetric analysis (TGA results showed that thermal stability of nanocomposites was notably improved compared to neat MC nylon6.

  4. Organic-Silica Interactions in Saline: Elucidating the Structural Influence of Calcium in Low-Salinity Enhanced Oil Recovery.

    Science.gov (United States)

    Desmond, J L; Juhl, K; Hassenkam, T; Stipp, S L S; Walsh, T R; Rodger, P M

    2017-09-08

    Enhanced oil recovery using low-salinity solutions to sweep sandstone reservoirs is a widely-practiced strategy. The mechanisms governing this remain unresolved. Here, we elucidate the role of Ca 2+ by combining chemical force microscopy (CFM) and molecular dynamics (MD) simulations. We probe the influence of electrolyte composition and concentration on the adsorption of a representative molecule, positively-charged alkylammonium, at the aqueous electrolyte/silica interface, for four electrolytes: NaCl, KCl, MgCl 2 , and CaCl 2 . CFM reveals stronger adhesion on silica in CaCl 2 compared with the other electrolytes, and shows a concentration-dependent adhesion not observed for the other electrolytes. Using MD simulations, we model the electrolytes at a negatively-charged amorphous silica substrate and predict the adsorption of methylammonium. Our simulations reveal four classes of surface adsorption site, where the prevalence of these sites depends only on CaCl 2 concentration. The sites relevant to strong adhesion feature the O - silica site and Ca 2+ in the presence of associated Cl - , which gain prevalence at higher CaCl 2 concentration. Our simulations also predict the adhesion force profile to be distinct for CaCl 2 compared with the other electrolytes. Together, these analyses explain our experimental data. Our findings indicate in general how silica wettability may be manipulated by electrolyte concentration.

  5. Glass formation, properties and structure of soda-yttria-silica glasses

    Science.gov (United States)

    Angel, Paul W.; Hann, Raiford E.

    1992-01-01

    The glass formation region of the soda yttria silicate system was determined. The glasses within this region were measured to have a density of 2.4 to 3.1 g/cu cm, a refractive index of 1.50 to 1.60, a coefficient of thermal expansion of 7 x 10(exp -6)/C, softening temperatures between 500 and 780 C, and Vickers hardness values of 3.7 to 5.8 GPa. Aqueous chemical durability measurements were made on select glass compositions while infrared transmission spectra were used to study the glass structure and its effect on glass properties. A compositional region was identified which exhibited high thermal expansion, high softening temperatures, and good chemical durability.

  6. Ceramic Composite Thin Films

    Science.gov (United States)

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

    2013-01-01

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

  7. Synthesis of titania modified silica-pillared clay (SPC) with highly ordered interlayered mesoporous structure for removing toxic metal ion Cr(VI) from aqueous state

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Huihui, E-mail: maohuihui_beijing@126.com [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Changzhou, Jiangsu Province 213164 (China); Zhu, Kongnan [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Changzhou, Jiangsu Province 213164 (China); Li, Baoshan, E-mail: bsli@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Yao, Chao; Kong, Yong [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Changzhou, Jiangsu Province 213164 (China)

    2014-02-15

    Titanium-functionalized silica-pillared clays synthesized through post synthetic route was utilized as adsorbers for the removal of Cr(VI) ions from aqueous solutions under different temperatures and initial concentrations. The starting mesostructured silica-pillared clay is assembled by intragallery ammonia-catalyzed hydrolysis of tetraethoxysilane using cationic surfactant as gallery template, and subsequently, the formed interlayered pore walls were decorated with nano-sized TiO{sub 2} particle through organic titanium functionalization process. The kind of structural transformation has been confirmed by X-ray diffraction (XRD), nitrogen adsorption–desorption isotherms, Fourier transform infrared (FT-IR) analysis, UV–vis diffuse reflectance spectroscopy (DRS), elemental analysis (XRF), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Such results indicate that most of the grafted titanium species was combined with Si–OH on the surface of gallery pores. By changing the concentration of organic titanium source during synthesis, the porous structure system is effected. Under suitable conditions, these materials exhibit high adsorption capacity and efficiency. Qualitative estimates of the thermodynamic parameters showed that the overall adsorption process is spontaneous (ΔG° < 0) and endothermic (ΔH° > 0). The adsorption isotherms of Cr(VI) on titanium-functionalized silica-pillared clay were best fitted by Redlich–Peterson models. Detail results of thermodynamics and kinetics are also presented.

  8. Synthesis of titania modified silica-pillared clay (SPC) with highly ordered interlayered mesoporous structure for removing toxic metal ion Cr(VI) from aqueous state

    International Nuclear Information System (INIS)

    Mao, Huihui; Zhu, Kongnan; Li, Baoshan; Yao, Chao; Kong, Yong

    2014-01-01

    Titanium-functionalized silica-pillared clays synthesized through post synthetic route was utilized as adsorbers for the removal of Cr(VI) ions from aqueous solutions under different temperatures and initial concentrations. The starting mesostructured silica-pillared clay is assembled by intragallery ammonia-catalyzed hydrolysis of tetraethoxysilane using cationic surfactant as gallery template, and subsequently, the formed interlayered pore walls were decorated with nano-sized TiO 2 particle through organic titanium functionalization process. The kind of structural transformation has been confirmed by X-ray diffraction (XRD), nitrogen adsorption–desorption isotherms, Fourier transform infrared (FT-IR) analysis, UV–vis diffuse reflectance spectroscopy (DRS), elemental analysis (XRF), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Such results indicate that most of the grafted titanium species was combined with Si–OH on the surface of gallery pores. By changing the concentration of organic titanium source during synthesis, the porous structure system is effected. Under suitable conditions, these materials exhibit high adsorption capacity and efficiency. Qualitative estimates of the thermodynamic parameters showed that the overall adsorption process is spontaneous (ΔG° 0). The adsorption isotherms of Cr(VI) on titanium-functionalized silica-pillared clay were best fitted by Redlich–Peterson models. Detail results of thermodynamics and kinetics are also presented.

  9. Use of Silica-Encapsulated Pseudomonas sp. Strain NCIB 9816-4 in Biodegradation of Novel Hydrocarbon Ring Structures Found in Hydraulic Fracturing Waters

    Science.gov (United States)

    Aukema, Kelly G.; Kasinkas, Lisa; Aksan, Alptekin

    2014-01-01

    The most problematic hydrocarbons in hydraulic fracturing (fracking) wastewaters consist of fused, isolated, bridged, and spiro ring systems, and ring systems have been poorly studied with respect to biodegradation, prompting the testing here of six major ring structural subclasses using a well-characterized bacterium and a silica encapsulation system previously shown to enhance biodegradation. The direct biological oxygenation of spiro ring compounds was demonstrated here. These and other hydrocarbon ring compounds have previously been shown to be present in flow-back waters and waters produced from hydraulic fracturing operations. Pseudomonas sp. strain NCIB 9816-4, containing naphthalene dioxygenase, was selected for its broad substrate specificity, and it was demonstrated here to oxidize fundamental ring structures that are common in shale-derived waters but not previously investigated with this or related enzymes. Pseudomonas sp. NCIB 9816-4 was tested here in the presence of a silica encasement, a protocol that has previously been shown to protect bacteria against the extremes of salinity present in fracking wastewaters. These studies demonstrate the degradation of highly hydrophobic compounds by a silica-encapsulated model bacterium, demonstrate what it may not degrade, and contribute to knowledge of the full range of hydrocarbon ring compounds that can be oxidized using Pseudomonas sp. NCIB 9816-4. PMID:24907321

  10. Single Site Silica Supported Tetramethyl Niobium by the SOMC Strategy: Synthesis, Characterization and Structure-Activity Relationship in Ethylene Oligomerization Reaction

    KAUST Repository

    Hamieh, Ali Imad Ali

    2017-06-06

    Silica supported Tetramethyl niobium complex [(≡SiO)NbMe4] 2 has been isolated by surface alkylation of [(≡SiO-)NbCl3Me] 1 with dimethyl zinc in pentane. 1 can be easily synthesized by grafting of NbCl3Me2 on to the surface of partially dehydroxylated silica by the SOMC strategy. Precise structural analysis was carried out by the FTIR, advance solid state NMR, elemental analysis and mass balance techniques (gas quantification after treating 2 with degassed water) . Complex 1 was found to be active in the ethylene oligomerization to produce up to C30, whereas to our surprise complex 2 selectively dimerizes ethylene into 1-butene in the absence of a co-catalyst at the same conversion levels.

  11. Single Site Silica Supported Tetramethyl Niobium by the SOMC Strategy: Synthesis, Characterization and Structure-Activity Relationship in Ethylene Oligomerization Reaction

    KAUST Repository

    Hamieh, Ali Imad Ali; Dey, Raju; Nekoueishahraki, Bijan; Samantaray, Manoja; Chen, Yin; Abou-Hamad, Edy; Basset, Jean-Marie

    2017-01-01

    Silica supported Tetramethyl niobium complex [(≡SiO)NbMe4] 2 has been isolated by surface alkylation of [(≡SiO-)NbCl3Me] 1 with dimethyl zinc in pentane. 1 can be easily synthesized by grafting of NbCl3Me2 on to the surface of partially dehydroxylated silica by the SOMC strategy. Precise structural analysis was carried out by the FTIR, advance solid state NMR, elemental analysis and mass balance techniques (gas quantification after treating 2 with degassed water) . Complex 1 was found to be active in the ethylene oligomerization to produce up to C30, whereas to our surprise complex 2 selectively dimerizes ethylene into 1-butene in the absence of a co-catalyst at the same conversion levels.

  12. The Structure and Stability of Molybdenum Ditelluride Thin Films

    Directory of Open Access Journals (Sweden)

    Zhouling Wang

    2014-01-01

    Full Text Available Molybdenum-tellurium alloy thin films were fabricated by electron beam evaporation and the films were annealed in different conditions in N2 ambient. The hexagonal molybdenum ditelluride thin films with well crystallization annealed at 470°C or higher were obtained by solid state reactions. Thermal stability measurements indicate the formation of MoTe2 took place at about 350°C, and a subtle weight-loss was in the range between 30°C and 500°C. The evolution of the chemistry for Mo-Te thin films was performed to investigate the growth of the MoTe2 thin films free of any secondary phase. And the effect of other postdeposition treatments on the film characteristics was also investigated.

  13. Synthesis and Gas Transport Properties of Hyperbranched Polyimide–Silica Hybrid/Composite Membranes

    Directory of Open Access Journals (Sweden)

    Masako Miki

    2013-12-01

    Full Text Available Hyperbranched polyimide–silica hybrids (HBPI–silica HBDs and hyperbranched polyimide–silica composites (HBPI–silica CPTs were prepared, and their general and gas transport properties were investigated to clarify the effect of silica sources and preparation methods. HBPI–silica HBDs and HBPI–silica CPTs were synthesized by two-step polymerization of A2 + B3 monomer system via polyamic acid as precursor, followed by hybridizing or blending silica sources. Silica components were incorporated by the sol-gel reaction with tetramethoxysilane (TMOS or the addition of colloidal silica. In HBPI-silica HBDs, the aggregation of silica components is controlled because of the high affinity of HBPI and silica caused by the formation of covalent bonds between HBPI and silica. Consequently, HBPI-silica HBDs had good film formability, transparency, and mechanical properties compared with HBPI-silica CPTs. HBPI-silica HBD and CPT membranes prepared via the sol-gel reaction with TMOS showed specific gas permeabilities and permselectivities for CO2/CH4 separation, that is, both CO2 permeability and CO2/CH4 selectivity increased with increasing silica content. This result suggests that gas transport can occur through a molecular sieving effect of the porous silica network derived from the sol-gel reaction and/or through the narrow interfacial region between the silica networks and the organic matrix.

  14. Structural characterization of the nickel thin film deposited by glad technique

    Directory of Open Access Journals (Sweden)

    Potočnik J.

    2013-01-01

    Full Text Available In this work, a columnar structure of nickel thin film has been obtained using an advanced deposition technique known as Glancing Angle Deposition. Nickel thin film was deposited on glass sample at the constant emission current of 100 mA. Glass sample was positioned 15 degrees with respect to the nickel vapor flux. The obtained nickel thin film was characterized by Force Modulation Atomic Force Microscopy and by Scanning Electron Microscopy. Analysis indicated that the formation of the columnar structure occurred at the film thickness of 1 μm, which was achieved for the deposition time of 3 hours. [Projekat Ministarstva nauke Republike Srbije, br. III45005

  15. Multifunctional thick-film structures based on spinel ceramics for environment sensors

    International Nuclear Information System (INIS)

    Vakiv, M; Hadzaman, I; Klym, H; Shpotyuk, O; Brunner, M

    2011-01-01

    Temperature sensitive thick films based on spinel-type NiMn 2 O 4 -CuMn 2 O 4 -MnCo 2 O 4 manganites with p- and p + -types of electrical conductivity and their multilayer p + -p structures were studied. These thick-film elements possess good electrophysical characteristics before and after long-term ageing test at 170 deg. C. It is shown that degradation processes connected with diffusion of metallic Ag into film grain boundaries occur in one-layer p-and p + -conductive films. Some part of the p + -p structures were of high stability, the relative electrical drift being no more than 1 %.

  16. Structural and electrical properties of sputter deposited ZnO thin films

    Science.gov (United States)

    Muhammed Shameem P., V.; Mekala, Laxman; Kumar, M. Senthil

    2018-05-01

    The growth of zinc oxide thin films having different oxygen content was achieved at ambient temperature by reactive dc magnetron sputtering technique and their structural and electrical properties are studied. The structural studies show that the films are polycrystalline with a preferential orientation of the grains along the c-axis [002], which increases with increase in oxygen partial pressure. The grain size and the surface roughness of the zinc oxide films are found to decrease with increasing oxygen partial pressure. It is observed that the resistivity of the zinc oxide films can be tuned from semiconducting to insulating regime by varying the oxygen content.

  17. Structural and electronic properties of polar MnO ultrathin film grown on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Asish K., E-mail: asish.kundu@saha.ac.in; Menon, Krishnakumar S. R. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 70064 (India)

    2016-05-23

    Surface electronic structure of ultrathin polar MnO film was studied by Low-energy Electron Diffraction (LEED) and Photoemission Spectroscopic (PES) techniques. Epitaxial monolayer to facet formation with increasing film thickness has been observed by LEED. Our LEED result shows p(2x2) surface reconstruction along with facet formation, stabilize the polar MnO(111) surface. The core levels and the valence band electronic structure of MnO films have been studied as a function of film thickness using X-ray and ultraviolet photoelectron spectroscopy techniques.

  18. Properties of planar structures based on Policluster films of diamond and AlN

    Science.gov (United States)

    Belyanin, A. F.; Luchnikov, A. P.; Nalimov, S. A.; Bagdasarian, A. S.

    2018-01-01

    AlN films doped with zinc were grown on Si substrates by RF magnetron reactive sputtering of a compound target. Policluster films of diamond doped with boron were formed on layered Si/AlN substrates from the gas phase hydrogen and methane, activated arc discharge. By electron microscopy, X-ray diffraction and Raman spectroscopy the composition and structure of synthetic policluster films of diamond and AlN films were studied. Photovoltaic devices based on the AlN/PFD layered structure are presented.

  19. Chloroform micro-evaporation induced ordered structures of poly(L-lactide) thin films

    DEFF Research Database (Denmark)

    Huang, Shaoyong; Li, Hongfei; Shang, Yingrui

    2013-01-01

    Self-assembly of poly(L-lactide) (PLLA) in thin films induced by chloroform micro-evaporation was investigated by microscopic techniques and X-ray diffraction studies. A film-thickness dependent on highly ordered structures has been derived from disordered films. Ring-banded spherulitic...... and dendritic morphologies with radial periodic variation of thicknesses were formed in dilute solution driven by micro-evaporation of the solvent. Bunched morphologies stacked with a flat-on lozenge-shaped lamellae were created in thinner films. The formation of the concentric ring banded structures...

  20. Solution processed pentacene thin films and their structural properties

    International Nuclear Information System (INIS)

    Tao Chunlan; Zhang Xuhui; Zhang Fujia; Liu Yiyang; Zhang Haoli

    2007-01-01

    The paper reported the solution process of pentacene thin films from organic solvent O-dichlorobenzene. The pentacene thin films obtained from different conditions were characterized by X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), and UV-vis spectroscopy. The result shows that the pentacene solution was successfully obtained at a minimum temperature of 40 deg. C. The optimum temperature of forming pentacene thin films was 100 deg. C

  1. Optical and structural characteristics of lead sulfides thin films

    International Nuclear Information System (INIS)

    Karim Deraman; Bakar Ismail; Samsudi Sakrani; Gould, R.D.

    1992-01-01

    Tin sulfide films have been prepared by evaporation technique at 1x10 - 4 torr and at substrate temperatures between 100 to 300 0 C. The films thickness were 52 to 370 nm. From the absorption 1.47 eV and X-ray diffraction patent shows that the composition of films have changed from SnS 2 (at low temperature) to SnS (at higher temperature)

  2. Structure and scintillation properties of CsI(Tl) films on Si single crystal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Lina [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Liu, Shuang, E-mail: shuangliu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Chen, Dejun; Zhang, Shangjian; Liu, Yong; Zhong, Zhiyong [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Falco, Charles M. [University of Arizona, College of Optical Sciences, AZ 85721 (United States)

    2016-10-30

    Highlights: • We obtained the desired micro-columnar structure of CsI(Tl) films on the orienting Si substrates. • We improved the micro-columnar structure of CsI(Tl) films under the relatively large deposition rate through using the substrate with a pre-deposited CsI nanolayer. • We modeled the interface structures between the CsI(Tl) films with (200) and (310) orientation and Si(111) substrates to explain the preferred orientation of film under the influence of the orienting substrate significantly. • We gained a new spectrum of the CsI(Tl) films peaked at 740 nm wavelength. - Abstract: CsI(Tl) scintillation films fabricated on glass substrates are widely applied for X-ray imaging because their ability to grow in micro-columnar structure and proper emission wavelength matching CCD cameras. But the coupling process between the CsI(Tl) films and Si-based photo detector would cause coupling loss. In this work, CsI(Tl) films were deposited on the orienting Si substrates and the Si substrates covered by the pre-deposited CsI nanolayers. Structure and scintillation properties of films were examined by using scanning electron microscopy, X-ray diffraction, photoluminescence and radioluminescent spectrum. The films deposited on the orienting Si substrates show the micro-columnar morphology with perfect single crystalline structure and the photoluminescence spectra with bimodal distribution. The performances of the films prepared on the pre-deposited CsI nanolayer, containing micro-columns structure and the light yield are improved.

  3. Structure and scintillation properties of CsI(Tl) films on Si single crystal substrates

    International Nuclear Information System (INIS)

    Guo, Lina; Liu, Shuang; Chen, Dejun; Zhang, Shangjian; Liu, Yong; Zhong, Zhiyong; Falco, Charles M.

    2016-01-01

    Highlights: • We obtained the desired micro-columnar structure of CsI(Tl) films on the orienting Si substrates. • We improved the micro-columnar structure of CsI(Tl) films under the relatively large deposition rate through using the substrate with a pre-deposited CsI nanolayer. • We modeled the interface structures between the CsI(Tl) films with (200) and (310) orientation and Si(111) substrates to explain the preferred orientation of film under the influence of the orienting substrate significantly. • We gained a new spectrum of the CsI(Tl) films peaked at 740 nm wavelength. - Abstract: CsI(Tl) scintillation films fabricated on glass substrates are widely applied for X-ray imaging because their ability to grow in micro-columnar structure and proper emission wavelength matching CCD cameras. But the coupling process between the CsI(Tl) films and Si-based photo detector would cause coupling loss. In this work, CsI(Tl) films were deposited on the orienting Si substrates and the Si substrates covered by the pre-deposited CsI nanolayers. Structure and scintillation properties of films were examined by using scanning electron microscopy, X-ray diffraction, photoluminescence and radioluminescent spectrum. The films deposited on the orienting Si substrates show the micro-columnar morphology with perfect single crystalline structure and the photoluminescence spectra with bimodal distribution. The performances of the films prepared on the pre-deposited CsI nanolayer, containing micro-columns structure and the light yield are improved.

  4. Structural and optical properties of nano-structured CdS thin films prepared by chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Rekha, E-mail: rekha.mittal07@gmail.com; Kumar, Dinesh; Chaudhar