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Sample records for multilayer nanocrystalline titania

  1. Study of hybrid solar cells made of multilayer nanocrystalline titania and poly(3-octylthiophene) or poly-(3-(2-methylhex-2-yl)-oxy-carbonyldithiophene)

    DEFF Research Database (Denmark)

    Antoniadou, Maria; Stathatos, Elias; Boukos, Nikolaos

    2009-01-01

    Hybrid solar cells have been constructed by using nanocrystalline titania and hole-transporting polymers. Titania was deposited on fluorine-doped tin-oxide transparent electrodes in three layers: a blocking layer and two nanostructured layers, giving densely packed or open structures. Open...

  2. Nanocrystalline hydroxyapatite/titania coatings on titanium improves osteoblast adhesion.

    Science.gov (United States)

    Sato, Michiko; Aslani, Arash; Sambito, Marisa A; Kalkhoran, Nader M; Slamovich, Elliott B; Webster, Thomas J

    2008-01-01

    Bulk hydroxyapatite (HA) and titania have been used to improve the osseointegration of orthopedic implants. For this reason, composites of HA and titania have been receiving increased attention in orthopedics as novel coating materials. The objective of this in vitro study was to produce nanophase (i.e., materials with grain size less than 100 nm) HA/titania coatings on titanium. The adhesion of bone forming cells (osteoblasts) on the composite coatings were also assessed and compared with single-phase nanotitania and nano-HA titanium coatings. Nanocrystalline HA powders were synthesized through wet chemistry and hydrothermal treatments at 200 degrees C. Nanocrystalline titania powders obtained commercially were mixed with the nanocrystalline HA powders at various weight ratios. The mixed powders were then deposited on titanium utilizing a room-temperature coating process called IonTite. The results of the present study showed that such coatings maintained the chemistry and crystallite size of the original HA and titania powders. Moreover, osteoblasts adherent on single-phase nanotitania coatings were well-spread whereas they became more round and extended distinct filopodia on the composite and single-phase HA coatings. Interestingly, the number of osteoblasts adherent on the nanotitania/HA composite coatings at weight ratios of 2/1 and 1/2 were significantly greater compared with single-phase nanotitania coatings, currently-used plasma-sprayed HA coatings, and uncoated titanium. These findings suggest that nanotitania/HA coatings on titanium should be further studied for improved orthopedic applications.

  3. Synthesis and characterisation of nanocrystalline titania spheres: Application to photocatalysis.

    OpenAIRE

    DeSouza, J. A.

    2005-01-01

    This thesis describes the making of titania nanocrystalline particles (photonic crystals) and their use as photocatalysts. Chapter 1 describes the work that motivates this research - this includes a description of these structures as propagating a 'slow photon' effect that could make them excellent photocatalysts for decomposing organic compounds. Chapter 2 describes the synthetic procedures that make these photonic crystals. The three-step procedure is detailed involving the infiltration of ...

  4. Bilirubin adsorption on nanocrystalline titania films

    Energy Technology Data Exchange (ETDEWEB)

    Yang Zhengpeng [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Si Shihui [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)]. E-mail: sishihui@mail.csu.edu.cn; Fung Yingsing [Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong (China)

    2007-02-26

    Bilirubin produced from hemoglobin metabolism and normally conjugated with albumin is a kind of lipophilic endotoxin, and can cause various diseases when its concentration is high. Bilirubin adsorption on the nanocrystalline TiO{sub 2} films was investigated using quartz crystal microbalance, UV-vis and IR techniques, and factors affecting its adsorption such as pH, bilirubin concentration, solution ionic strength, temperature and thickness of TiO{sub 2} films were discussed. The amount of adsorption and parameters for the adsorption kinetics were estimated from the frequency measurements of quartz crystal microbalance. A fresh surface of the nanocrystalline TiO{sub 2} films could be photochemically regenerated because holes and hydroxyl radicals were generated by irradiating the nanocrystalline TiO{sub 2} films with UV light, which could oxidize and decompose organic materials, and the nanocrystalline TiO{sub 2} films can be easily regenerated when it is used as adsorbent for the removal of bilirubin.

  5. Synthesis and self-assembly of photonic materials from nanocrystalline titania sheets.

    Science.gov (United States)

    Zhu, Jian; Wang, Jinguo; Lv, Fujian; Xiao, Shengxiong; Nuckolls, Colin; Li, Hexing

    2013-03-27

    We describe the use of benzyl alcohols in a solvothermal/alcoholysis reaction to form nanocrystalline sheets of anatase titania. By tuning the reaction conditions, we adjust the size of the nanosheets. The type and density of benzyl groups that decorate the basal plane of the titania sheets control the self-assembly into layered structures. These layered materials can be grown from solid substrates to create iridescent thin films that reflect specific wavelengths of visible light.

  6. Novel Approach for the Synthesis of Nanocrystalline Anatase Titania and Their Photovoltaic Application

    Directory of Open Access Journals (Sweden)

    Pavuluri Srinivasu

    2011-01-01

    Full Text Available High surface area titania with crystalline anatase walls has been synthesized using ordered large mesoporous carbon as a template. The pore structure of mesoporous carbon is infiltrated with titanium tetraisopropoxide solution at room temperature and the mixture is subjected to heat treatment at 550oC in presence of air to complete removal of the template. The prepared crystalline anatase frameworks are characterized by XRD, N2 adsorption and HR-TEM. The nitrogen adsorption-desorption analysis of the prepared anatase titania particles exhibits BET specific surface area of 28 m2/g. The dye-sensitized solar cells performance of this anatase titania material has been tested and energy conversion efficiency of 3.0% is achieved under AM 1.5 sunlight. This work reports a new approach for fabrication of nanocrystalline anatase titania by simple hard templating technique for the first time and their applications for dye-sensitized solar cell.

  7. Coupling of titania inverse opals to nanocrystalline titania layers in dye-sensitized solar cells.

    Science.gov (United States)

    Lee, Seung-Hyun Anna; Abrams, Neal M; Hoertz, Paul G; Barber, Greg D; Halaoui, Lara I; Mallouk, Thomas E

    2008-11-20

    We report a quantitative comparison of the photoaction spectra, short circuit current densities, and power conversion efficiencies of dye-sensitized solar cells (DSSCs) that contain bilayers of nanocrystalline TiO2 (nc-TiO2) and titania inverse opal photonic crystals (PCs). Cells were fabricated with PC/nc-TiO2 and nc-TiO2/PC bilayer films on glass/tin oxide anode of the cell, as well as in a split configuration in which the nc-TiO2 and PC layers were deposited on the anode and cathode sides of the cell, respectively. Incident photon current efficiencies at single wavelengths and current-voltage curves in white light were obtained with both cathode and anode side illumination. The results obtained support a model proposed by Miguez and co-workers, in which coupling of the low refractive index PC layer to the higher index nc-TiO2 layer creates a standing wave in the nc-TiO2 layer, enhancing the response of the DSSC in the red region of the spectrum. This enhancement is very sensitive to the degree of physical contact between the two layers. A gap on the order of 200 nm thick, created by a polymer templating technique, is sufficient to decouple the two layers optically. The coupling of the nc-TiO2 and PC layers across the gap could be improved slightly by treatment with TiCl4 vapor. In the bilayer configuration, there is an enhancement in the IPCE across the visible spectrum, which is primarily caused by defect scattering in the PC layer. There is also an increase of 20-50 mV in the open circuit photovoltage of the cell. With anode side illumination, the addition of a PC layer to the nc-TiO2 layer increased the efficiency of DSSCs from 6.5 to 8.3% at a constant N719 dye loading of 155-160 nmol/cm2.

  8. Antibacterial performance of nanocrystallined titania confined in mesoporous silica nanotubes.

    Science.gov (United States)

    Cendrowski, Krzysztof; Peruzynska, Magdalena; Markowska-Szczupak, Agata; Chen, Xuecheng; Wajda, Anna; Lapczuk, Joanna; Kurzawski, Mateusz; Kalenczuk, Ryszard J; Drozdzik, Marek; Mijowska, Ewa

    2014-06-01

    In this paper, we study synthesis and characteristics of mesoporous silica nanotubes modified by titanium dioxide, as well as their antimicrobial properties and influence on mitochondrial activity of mouse fibroblast L929. Nanocrystalized titania is confined in mesopores of silica nanotubes and its light activated antibacterial response is revealed. The analysis of the antibacterial effect on Escherichia coli. (ATCC 25922) shows strong enhancement during irradiation with the artificial visible and ultraviolet light in respect to the commercial catalyst and control sample free from the nanomaterials. In darkness, the mesoporous silica/titania nanostructures exhibited antibacterial activity dependent on the stirring speed of the suspension containing nanomaterials. Obtained micrograph proved internalization of the sample into the microorganism trough the cell membrane. The analysis of the mitochondrial activity and amount of lactate dehydrogenase released from mouse fibroblast cells L929 in the presence of the sample were determined with LDH and WST1 assays, respectively. The synthesized silica/titania antibacterial agent also exhibits pronounced photoinduced inactivation of the bacterial growth under the artificial visible and UV light irritation in respect to the commercial catalyst. Additionally, mesoporous silica/titania nanotubes were characterized in details by means of high resolution transmission electron microscopy (HR-TEM), XRD and BET Isotherm.

  9. Flame synthesis and characterization of nanocrystalline titania powders

    Directory of Open Access Journals (Sweden)

    Bhaskaran Manjith Kumar

    2012-09-01

    Full Text Available Flame reactors are considered to be one of the most promising and versatile synthesis routes for the largescale production of submicron and nanosized particles. An annular co-flow type oxy-gas diffusion burner was designed for its application in a modular flame reactor for the synthesis of nanocrystalline oxide ceramics. The burner consisted of multiple ports for the individually regulated flow of a precursor vapour, inert gas, fuel gas and oxidizer. The nanopowders formed during flame synthesis in the reaction chamber were collected by a suitable set of filters. In the present study, TTIP was used as the precursor for the synthesis of nanocrystalline TiO2 and helium was used to carry the precursor vapour to the burner head. Methane and oxygen were used as fuel and oxidizer respectively. The operating conditions were varied by systematically changing the flow rates of the gases involved. The synthesized powders were characterized using standard techniques such as XRD, SEM, TEM, BET etc., in order to determine the crystallite size, phase content, morphology, particle size and degree of agglomeration. The influences of gas flow rates on the powder characteristics are discussed.

  10. Size-dependent behavior of nanocrystalline titania and iron oxyhydroxide biominerals

    Science.gov (United States)

    Banfield, Jillian F.

    2000-03-01

    Biomineralization and chemical weathering products are predominantly nanocrystalline. Such phases comprise the majority of reactive surface area in soils and sediments. Microbial oxidation of dissolved iron leads to precipitation of nanocrystalline Fe-oxyhydroxides. Initial ~ 2nm diameter ferrihydrite-like particles nucleate on microbial polymers and form submicron-diameter spherical aggregates via floculation in solution. We have used titania (TiO2) as a model system to explore relationships between size and structure, phase stability, crystal growth mechanisms, phase transformation kinetics, and surface properties. Initial amorphous titania sol-gel products restructure to form 2-4 nm particles that, upon heating, grow to ~ 5 nm, then transform to anatase. Molecular dynamics simulations suggest conversion from four and five coordinated Ti4+ in < 3 nm particles to octahedrally coordinated Ti4+ in larger particles. Four and five coordinated Ti sites are supported by prior synchrotron-based studies on nanotitania. Furthermore, calculated XRD patterns for energy-minimized 2 nm particle structures coincide well with experimental patterns. Particle growth primarily occurs via solid state oriented attachment. Small misorientations between adjacent particles introduce new structural components, as well as dislocations and extended defects that can serve as nucleation sites for subsequent phase transformations. 2-3 nm ferrihydrites transform to ~ 3-6 nm randomly oriented feroxyhyte and goethite (FeOOH) crystals. FeOOH nanocrystals aggregate via oriented attachment to form tens of nanometer diameter imperfect single crystals. The sequence of crystallization steps and similarities in crystal growth and defect formation mechanisms in the titania and iron systems suggest oriented attachment is an important pathways for structural change and crystal growth in many natural and synthetic nanophase materials.

  11. Multifunctional alumina/titania hybrid blocking layer modified nanocrystalline titania films as efficient photoanodes in dye sensitized solar cells

    Science.gov (United States)

    Wang, Changlei; Yu, Zhenhua; Bu, Chenghao; Liu, Pei; Bai, Sihang; Liu, Chang; Kondamareddy, Kiran Kumar; Sun, Weiwei; Zhan, Kan; Zhang, Kun; Guo, Shishang; Zhao, Xingzhong

    2015-05-01

    A facile way of fabricating efficient blocking layer on mesoporous TiO2 film of dye-sensitized solar cells (DSSCs) is demonstrated here for the first time. Al2O3 and TiO2 are combined together to form a blocking layer. A simple spin coating technique is employed which is a versatile and low-cost method over the atomic layer deposition (ALD) technique. Multifunctional alumina/titania (Al2O3/TiO2) hybrid overlayer is prepared on traditional TiO2 nanocrystalline thin film surface, through sequential deposition of AlCl3·6H2O and TiCl4 precursor solutions followed by sintering at 500 °C for 30 min. Al2O3 effectively plays its role in retarding interfacial recombination of electrons and improving open circuit potential (Voc), while the tiny TiO2 clusters synthesized from TiCl4 treatment act as electron transporting channels to facilitate electron diffusion which leads to enhanced photocurrent (Jsc). Compared to the device without blocking layer, the DSSCs assembled with Al2O3/TiO2 hybrid blocking layer showed improvement in Jsc (from 13.09 mA/cm2 to 16.90 mA/cm2) as well as in Voc (from 0.72 V to 0.73 V) resulting a much better conversion efficiency of 8.60%.

  12. The role of nanocrystalline titania coating on nanostructured austenitic stainless steel in enhancing osteoblasts functions for regeneration of tissue

    Energy Technology Data Exchange (ETDEWEB)

    Shah, J.S.; Venkatsurya, P.K.C.; Thein-Han, W.W. [Biomaterials and Biomedical Engineering Research Laboratory, Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504 (United States); Misra, R.D.K., E-mail: dmisra@louisiana.edu [Biomaterials and Biomedical Engineering Research Laboratory, Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504 (United States); Pesacreta, T.C. [Department of Biology, University of Louisiana at Lafayette, P.O. Box 42451, Lafayette, LA 70504 (United States); Somani, M.C.; Karjalainen, L.P. [Department of Mechanical Engineering, University of Oulu, P.O. Box 4200, 90014 Oulu (Finland)

    2011-03-12

    In the context of osseointegration of metallic implants, while nanostructuring the surface favorably modulates cellular response, the disinfective attributes required during the healing process are not available. Thus, in the present study, we demonstrate that nanocrystalline titania provides cumulative benefit of enhancing osteoblasts functions to promote the efficacy of metal implants together with the disinfective attributes. To this end, the primary objective here is to examine the select functions of bone forming cells (osteoblasts) on electrocrystallized nanonodular titania-coated nanograined/ultrafine grained (NG/UFG) austenitic stainless steel. The accompanying objective is to study the disinfective/antimicrobial activity. To the best of our understanding this is the first study of nanophase titania on a non-titanium substrate. The osteoblasts functions were investigated in terms of cell attachment, proliferation, and quantitative analysis of proteins, actin and vinculin. In comparison to the bare NG/UFG substrate, the nanophase titania-coated substrate exhibited higher degree of cell attachment and proliferation which are regulated via cellular and molecular interactions with proteins, actin and vinculin. The enhanced functions of osteoblasts suggest that nanophase titania adsorbs extracellular matrix proteins, fibronectin and vitronectin from serum enhancing protein, with subsequent binding of integrins and osteoblasts precursor to titania. The antimicrobial attributes assessed in terms of degradation of methyl orange and effectiveness in killing E. coli supports the viewpoint that large surface area of titania would be instrumental in reducing the detrimental effect of biologically reactive oxygen species produced by macrophages in the vicinity of the metal bone/implant interface. In summary, the study provides some new insights concerning nanostructuring of metallic substrates with specific physical and surface properties for medical devices with

  13. Enhancing the photoelectric conversion of dye-sensitized solar cell via nitrogen-doped nanocrystalline titania electrode.

    Science.gov (United States)

    Cheng, Ping; Lan, Tian; Yang, Haijun; Wang, Wanjun; Wu, Haixia; Deng, Changsheng; Dai, Xiaming; Guo, Shouwu

    2010-11-01

    A high efficient dye-sensitized solar cell (DSC) was fabricated using nitrogen-doped nanocrystalline titania(TiO2) photoanode. X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), X-ray powder diffraction (XRD), zeta potentials, nitrogen adsorption-desorption and elemental analysis experiments were employed to characterize the nitrogen-doped nanocrystalline TiO2 photoanode. An obvious enhancement of the optical absorption in the range of 380-550 nm was observed for nitrogen-doped TiO2, which was attributed to both the substitutional N and the chemisorbed N2 molecules. A conversion efficiency of 9.04% was obtained on the DSC based on nitrogen-doped TiO2 photoanode annealed in a flow of NH3 at 550 degrees C, with an increase of 15.6% improvement in comparison with pure TiO2 (7.82%). The mechanism for the enhanced photovoltaic performance was discussed.

  14. Surface Properties of Photocatalytic Nano-Crystalline Titania Films and Reactor for Photocatalytic Degradation of Chloroform

    DEFF Research Database (Denmark)

    Søgaard, Erik Gydesen; Simonsen, Morten Enggrob; Jensen, Henrik

    2006-01-01

    In this work two immobilizations techniques of TiO2 onto glass were investigated; deposition of previously made titania powder (PMTP) and a sol-gel method. The titania powder used in this work was Degussa P25, Hombikat UV100 and a powder prepared in our laboratory SC134. The prepared TiO2 films w...

  15. Nanocrystalline TiO{sub 2} photocatalytic membranes with a hierarchical mesoporous multilayer structure: synthesis, characterization, and multifunction

    Energy Technology Data Exchange (ETDEWEB)

    Choi, H.; Dionysiou, D.D. [Department of Civil and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221-0071 (United States); Sofranko, A.C. [Department of Chemical Engineering, University of Virginia, Charlottesville, VA 22904-4741 (United States)

    2006-05-19

    A novel sol-gel dip-coating process to fabricate nanocrystalline TiO{sub 2} photocatalytic membranes with a robust hierarchical mesoporous multilayer and improved performance has been studied. Various titania sols containing poly(oxyethylenesorbitan monooleate) (Tween 80) surfactant as a pore-directing agent to tailor-design the porous structure of TiO{sub 2} materials at different molar ratios of Tween 80/isopropyl alcohol/acetic acid/titanium tetraisopropoxide = R:45:6:1 have been synthesized. The sols are dip-coated on top of a homemade porous alumina substrate to fabricate TiO{sub 2}/Al{sub 2}O{sub 3} composite membranes, dried, and calcined, and this procedure is repeated with varying sols in succession. The resulting asymmetric mesoporous TiO{sub 2} membrane with a thickness of 0.9 {mu}m exhibits a hierarchical change in pore diameter from 2-6, through 3-8, to 5-11 nm from the top to the bottom layer. Moreover, the corresponding porosity is incremented from 46.2, through 56.7, to 69.3 %. Compared to a repeated-coating process using a single sol, the hierarchical multilayer process improves water permeability significantly without sacrificing the organic retention and photocatalytic activity of the TiO{sub 2} membranes. The prepared TiO{sub 2} photocatalytic membrane has great potential in developing highly efficient water treatment and reuse systems, for example, decomposition of organic pollutants, inactivation of pathogenic microorganisms, physical separation of contaminants, and self-antifouling action because of its multifunctional capability. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  16. Surface Properties of Photocatalytic Nano-Crystalline Titania Films and Reactor for Photocatalytic Degradation of Chloroform

    DEFF Research Database (Denmark)

    Søgaard, Erik Gydesen; Simonsen, Morten Enggrob; Jensen, Henrik

    2006-01-01

    In this work two immobilizations techniques of TiO2 onto glass were investigated; deposition of previously made titania powder (PMTP) and a sol-gel method. The titania powder used in this work was Degussa P25, Hombikat UV100 and a powder prepared in our laboratory SC134. The prepared TiO2 films w......, as it was observed that the position of the coated lamp in the reactor yield different degradation rates....

  17. A Modified Thermal Treatment Method for the Up-Scalable Synthesis of Size-Controlled Nanocrystalline Titania

    Directory of Open Access Journals (Sweden)

    Aysar Sabah Keiteb

    2016-10-01

    Full Text Available Considering the increasing demand for titania nanoparticles with controlled quality for various applications, the present work reports the up-scalable synthesis of size-controlled titanium dioxide nanocrystals with a simple and convenient thermal treatment route. Titanium dioxide nanocrystals with tetragonal structure were synthesized directly from an aqueous solution containing titanium (IV isopropoxide as the main reactant, polyvinyl pyrrolidone (PVP as the capping agent, and deionized water as a solvent. With the elimination of the drying process in a thermal treatment method, an attempt was made to decrease the synthesis time. The mixture directly underwent calcination to form titanium dioxide (TiO2 nanocrystalline powder, which was confirmed by FT-IR, energy dispersive X-ray spectroscopy (EDX, and X-ray diffraction (XRD analysis. The control over the size and optical properties of nanocrystals was achieved via variation in calcination temperatures. The obtained average sizes from XRD spectra and transmission electron microscopy (TEM images showed exponential variation with increasing calcination temperature. The optical properties showed a decrease in the band gap energy with increasing calcination temperature due to the enlargement of the nanoparticle size. These results prove that direct calcination of reactant solution is a convenient thermal treatment route for the potential large-scale production of size-controlled Titania nanoparticles.

  18. Combination of surface nanocrystallization and co-rolling: Creating multilayer nanocrystalline composites

    Energy Technology Data Exchange (ETDEWEB)

    Waltz, L. [Institute Charles Delaunay, FRE CNRS 2848, LASMIS, University of Technology of Troyes, 10000 Troyes (France); Retraint, D. [Institute Charles Delaunay, FRE CNRS 2848, LASMIS, University of Technology of Troyes, 10000 Troyes (France)], E-mail: delphine.retraint@utt.fr; Roos, A. [Institute Charles Delaunay, FRE CNRS 2848, LASMIS, University of Technology of Troyes, 10000 Troyes (France); Olier, P. [DEN/DNM/SRMA/LTMEX, Commissariat a l' Energie Atomique de Saclay, 91191 Gif-sur-Yvette (France)

    2009-01-15

    This paper describes a combination of surface mechanical attrition treatment and co-rolling performed at 550 deg. C. This duplex method leads to the formation of a semi-massive multilayer structure of alternating nanocrystalline layers, transition layers and coarse-grained layers. Transmission electron microscopy observations correlated with nanoindentation hardness measurements demonstrate that the nano- and subnanocrystalline layers are preserved after the process. Tensile tests showed improved yield and ultimate strengths, and acceptable ductility.

  19. Study of Degradation Kinetics of Parathion Methyl On Mixed Nanocrystalline Titania-Zirconium and Titania-Cerium Oxides

    Science.gov (United States)

    Kuráň, Pavel; Pšenička, Martin; Šťastný, Martin; Benkocká, Monika; Janoš, Pavel

    2016-10-01

    The unique surface properties of some nanocrystalline metal oxides and their application for removal of various toxic compounds were reported in early 1990s. Recently, a reliable method for the preparation of reactive cerium dioxide sorbent and its application for degradation of the organophosphate pesticides, such as parathion methyl, chlorpyrifos, dichlofenthion, fenchlorphos, and prothiofos, as well as of some chemical warfare agents-nerve gases soman and O-ethyl S-[2-(diisopropylamino) ethyl] methylphosphonothioate (VX) was published. This paper reports on the kinetics study of degradation of parathion methyl as a representative organophosphate on nanocrystalline metal oxides TiO2, ZrO2, CeO2 and their mixtures in different molar ratios of particular elements. The tested sorbents except of CeO2 were prepared by different methods (e.g. sol-gel, precipitation) in cooperation with Institute of Inorganic Chemistry (Rez, Czech Republic). The degradation kinetics of parathion methyl on tested sorbents was followed by HPLC equipped with diode array detector. The basic kinetics parameters (half-lives of parathion methyl degradation, rate constants of degradation product formation) were calculated for each sorbent from Weber-Morris equation of 1st order diffusion kinetic model. The results proved the ability of prepared sorbents to degrade parathion methyl under formation of 4-nitrophenol as the main degradation product. The most efficient sorbents were TiCe (2:8), TiCe (1:1), TiCe (0:1) (50-70 %) followed by TiZr (1:1), TiCe (8:2), TiZr (8:2), TiZr (2:8) (20-30%) and TiO2, ZrO2 (less than 5 %).

  20. Photodegradation of the herbicide azimsulfuron using nanocrystalline titania films as photocatalyst and low intensity Black Light radiation or simulated solar radiation as excitation source

    Energy Technology Data Exchange (ETDEWEB)

    Pelentridou, Katerina [Engineering Science Department, University of Patras, 26500 Patras (Greece); Stathatos, Elias [Electrical Engineering Department, Technological-Educational Institute of Patras, 26334 Patras (Greece)], E-mail: estathatos@teipat.gr; Karasali, Helen [Benaki Phytopathological Institute, Pesticide control and Phytopharmacy, Athens (Greece); Lianos, Panagiotis [Engineering Science Department, University of Patras, 26500 Patras (Greece)], E-mail: lianos@upatras.gr

    2009-04-30

    Aqueous solutions of the herbicide azimsulfuron have been treated by a photocatalytic process employing titania nanocrystalline films as photocatalyst. Results showed that solutions of this herbicide at maximum possible concentration can be photodegraded in a time of a few hours by using low intensity UVA radiation comparable with that of the UVA of solar noon. Similar results have also been obtained with simulated solar radiation. Thus heterogeneous photocatalysis can be employed for the treatment of waters polluted by this herbicide.

  1. Preservation of the morphology of a self-encapsulated thin titania film in a functional multilayer stack: an X-ray scattering study.

    Science.gov (United States)

    Perlich, Jan; Memesa, Mine; Diethert, Alexander; Metwalli, Ezzeldin; Wang, Weinan; Roth, Stephan V; Timmann, Andreas; Gutmann, Jochen S; Müller-Buschbaum, Peter

    2009-03-23

    Tailoring of the titania morphology is achieved by the combination of a triblock copolymer, acting as structure-directing agent, and a sol-gel chemistry enabling the incorporation of the provided inorganic material (titania) into the selected phase of the triblock copolymer. Spin-coating of the solution on FTO-coated glass, followed by plasma etching and calcination of the thin film results in the formation of self-encapsulated crystalline titania nanostructures. The fabricated nanostructures are coated stepwise with dye, conductive polymers and gold forming a functional multilayer stack. An advanced small-angle scattering technique probing the sample with X-ray synchrotron radiation under grazing incidence (GISAXS) is employed for the characterization of the preparation route, as scattering allows accessing the structure inside the multilayers. The tailored titania morphology is preserved during the preparation route towards the functional multilayer stack of a photovoltaic demonstration cell. Two clearly distinguishable structures originate from the substrate and the titania templated by the triblock copolymer; hence the other layers induce no additional structures. Therefore, this investigation provides the evidence that the effort spent to tailor the morphology is justified by the preservation of the self-encapsulated titania morphology that is created by the structure-directing agent throughout the functional multilayer stack build-up.

  2. Correlation of the heterogeneous discoloration efficiency of aqueous Rhodamine-B solutions and charge separation enhancement of mixed-phase nanocrystalline titania

    Science.gov (United States)

    Zhang, Dongfang

    2012-05-01

    Heterogeneous photocatalytic removal of Rhodamine-B (RhB) dye from liquid phase was done using mixed-phase nanocrystalline TiO2 for enhancement of charge separation and UV-visible-light-driven photocatalysis capabilities. The mixed-phase nanocrystalline TiO2 was characterized using various analytical techniques including XRD, TEM, UV-vis DRS and PL to investigate its phase composition and structure, nanocrystalline size distribution, band gap energy, and photoluminescence properties. The photocatalytic discoloration efficiency of mixed-phase nanocrystalline titania was explored by monitoring the decomposition of RhB dye in an aqueous solution. The results showed that the as-prepared mixed-phase nanocrystalline TiO2 was excellent for degradation of RhB molecule, and the combination of crystal phase of anatase and rutile has great effect on decomposition of RhB. The kinetic studies demonstrate that the photocatalytic oxidation reaction followed a pseudo-first-order expression due to the evidence of linear correlation between ln( c/c 0) vs. reaction time t. Moreover, the aqueous RhB dye decomposition over the as-prepared mixed-phase nanocrystalline TiO2 catalyst is controlled by RhB pre-adsorption.

  3. Nanocrystalline Anatase Titania Supported Vanadia Catalysts: Facet-dependent Structure of Vanadia

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei-Zhen; Gao, Feng; Li, Yan; Walter, Eric D.; Liu, Jun; Peden, Charles HF; Wang, Yong

    2015-07-09

    Titania supported vanadia, a classic heterogeneous catalyst for redox reactions, typically has nonhomogeneous vanadia species on various titania facets, making it challenging not only to determine and quantify each species but also to decouple their catalytic contributions. We prepared truncated tetragonal bipyramidal (TiO2-TTB) and rod-like (TiO2-Rod) anatase titania with only {101} and {001} facets at ratios of about 80:20 and 93:7, respectively, and used them as supports of sub-monolayer vanadia. The structure and redox properties of supported vanadia were determined by XRD, TEM, XPS, EPR, Raman, FTIR and TPR, etc. It was found that vanadia preferentially occupy TiO2 {001} facets and form isolated O=V4+(O-Ti)2 species, and with further increase in vanadia surface coverage, isolated O=V5+(O-Ti)3 and oligomerized O=V5+(O-M)3 (M = Ti or V) species form on TiO2 {101} facets. The discovery on support facet-dependent structure of vanadia on anatase titania is expected to enable the elucidation of structure-function correlations on high surface area TiO2 supported vanadia catalysts. This work was supported by U. S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Biosciences and Geosciences. The research was performed in the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE Office of Biological and Environmental Research, and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for DOE by Battelle.

  4. Hydrogen Passivation Effect on Enhanced Luminescence from Nanocrystalline Si/SiO2 Multilayers

    Institute of Scientific and Technical Information of China (English)

    XIA Zheng-Yue; HAN Pei-Gao; XU Jun; CHEN De-Yuan; WEI De-Yuan; MA Zhong-Yuan; CHEN Kun-Ji; XU Ling; HUANG Xin-Fan

    2007-01-01

    Nanocrystalline Si/SiO2 multilayers are prepared by thermally annealing amorphous Si/SiO2 stacked structures.The photoluminescence intensity is obviously enhanced after hydrogen passivation at various temperatures. It is suggested that the hydrogen trapping and detrapping processes at different temperatures strongly influence the passivation effect. Direct experimental evidence is given by electron spin resonance spectra that hydrogen effectively reduces the nonradiative defect states existing in the Si nanocrystas/SiO2 system which enhances the radiative recombination probability. The luminescence characteristic shows its stability after hydrogen passivation even after aging eight months.

  5. Ultrahigh Tensile Strength Nanowires with a Ni/Ni-Au Multilayer Nanocrystalline Structure.

    Science.gov (United States)

    An, Boo Hyun; Jeon, In Tak; Seo, Jong-Hyun; Ahn, Jae-Pyoung; Kraft, Oliver; Choi, In-Suk; Kim, Young Keun

    2016-06-08

    Superior mechanical properties of nanolayered structures have attracted great interest recently. However, previously fabricated multilayer metallic nanostructures have high strength under compressive load but never reached such high strength under tensile loads. Here, we report that our microalloying-based electrodeposition method creates a strong and stable Ni/Ni-Au multilayer nanocrystalline structure by incorporating Au atoms that makes nickel nanowires (NWs) strongest ever under tensile loads even with diameters exceeding 200 nm. When the layer thickness is reduced to 10 nm, the tensile strength reaches the unprecedentedly high 7.4 GPa, approximately 10 times that of metal NWs with similar diameters, and exceeding that of most metal nanostructures previously reported at any scale.

  6. Designing a stronger interface through graded structures in amorphous/nanocrystalline ZrCu/Cu multilayered films.

    Science.gov (United States)

    Chang, C H; Hsieh, C H; Huang, J C; Wang, C; Liao, Y C; Hsueh, C H; Du, X H; Wang, Z K; Wang, X

    2016-06-03

    Many multilayered nano-structures appear to fail due to brittle matter along the interfaces. In order to toughen them, in this study, the microstructure and interface strength of multilayered thin films consisting of amorphous ZrCu and nanocrystalline Cu (with sharp or graded interfaces) are examined and analyzed. The interface possesses a gradient nature in terms of composition, nanocrystalline phase size and volume fraction. The bending results extracted from the nano-scaled cantilever bending samples demonstrate that multilayered films with graded interfaces would have a much higher interface bending strength/strain/modulus, and an overall improvement upgrade of more than 50%. The simple graded interface design of multilayered thin films with improved mechanical properties can offer much more promising performance in structural and functional applications for MEMS or optical coating.

  7. Henna (Lawsonia inermis L. Dye-Sensitized Nanocrystalline Titania Solar Cell

    Directory of Open Access Journals (Sweden)

    Khalil Ebrahim Jasim

    2012-01-01

    Full Text Available Low-cost solar cells have been the subject of intensive research activities for over half century ago. More recently, dye-sensitized solar cells (DSSCs emerged as a new class of low-cost solar cells that can be easily prepared. Natural-dye-sensitized solar cells (NDSSCs are shown to be excellent examples of mimicking photosynthesis. The NDSSC acts as a green energy generator in which dyes molecules adsorbed to nanocrystalline layer of wide bandgap semiconductor material harvest photons. In this paper we investigate the structural, optical, electrical, and photovoltaic characterization of two types of natural dyes, namely, the Bahraini Henna and the Yemeni Henna, extracted using the Soxhlet extractor. Solar cells from both materials were prepared and characterized. It was found that the levels of open-circuit voltage and short-circuit current are concentration dependent. Further suggestions to improve the efficiency of NDSSC are discussed.

  8. Suspension Plasma Spray Fabrication of Nanocrystalline Titania Hollow Microspheres for Photocatalytic Applications

    Science.gov (United States)

    Ren, Kun; Liu, Yi; He, Xiaoyan; Li, Hua

    2015-10-01

    Hollow inorganic microspheres with controlled internal pores in close-cell configuration are usually constructed by submicron-sized particles. Fast and efficient large-scale production of the microspheres with tunable sizes yet remains challenging. Here, we report a suspension plasma spray route for making hollow microspheres from nano titania particles. The processing permits most nano particles to retain their physiochemical properties in the as-sprayed microspheres. The microspheres have controllable interior cavities and mesoporous shell of 1-3 μm in thickness. Spray parameters and organic content in the starting suspension play the key role in regulating the efficiency of accomplishing the hollow sphere structure. For the ease of collecting the spheres for recycling use, ferriferous oxide particles were used as additives to make Fe3O4-TiO2 hollow magnetic microspheres. The spheres can be easily recycled through external magnetic field collection after each time use. Photocatalytic anti-bacterial activities of the hollow spheres were assessed by examining their capability of degrading methylene blue and sterilizing Escherichia coli bacteria. Excellent photocatalytic performances were revealed for the hollow spheres, giving insight into their potential versatile applications.

  9. A multilayer innovative solution to improve the adhesion of nanocrystalline diamond coatings

    Energy Technology Data Exchange (ETDEWEB)

    Poulon-Quintin, A., E-mail: poulon@icmcb-bordeaux.cnrs.fr [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Faure, C.; Teulé-Gay, L.; Manaud, J.P. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France)

    2015-03-15

    Highlights: • Improvement of the NCD adhesion on WC-12%Co substrates for tooling applications using a multi-interlayer additional system. • Reduction of the graphite layer thickness and continuity at the interface with the diamond. • Transmission electron microscopy study for a better understanding of the diffusion phenomena occurring at the interfaces. - Abstract: Nano-crystalline diamond (NCD) films grown under negative biased substrates by chemical vapor deposition (CVD) are widely used as surface overlay coating onto cermet WC-Co cutting tools to get better performances. To improve the diamond adhesion to the cermet substrate, suitable multi-layer systems have been added. They are composed of a cobalt diffusion barrier close to the substrate (single and sequenced nitrides layers) coated with a nucleation extra layer to improve the nucleus density of diamond during CVD processing. For all systems, before and after diamond deposition, transmission electron microscopy (TEM) has been performed for a better understanding of the diffusion phenomena occurring at the interfaces and to evaluate the presence of graphitic species at the interface with the diamond. Innovative multilayer system dedicated to the regulation of cobalt diffusion coated with a bilayer system optimized for the carbon diffusion control, is shown as an efficient solution to significantly reduce the graphite layer formation at the interface with the diamond down to 10 nm thick and to increase the adhesion of NCD diamond layer as scratch-tests confirm.

  10. Deposition and characterization of titania-silica optical multilayers by asymmetric bipolar pulsed dc sputtering of oxide targets

    Energy Technology Data Exchange (ETDEWEB)

    Sagdeo, P R; Shinde, D D; Misal, J S [Optics and Thin Film Laboratory, Autonagar, BARC-Vizag, Visakhapatnam -530012 (India); Kamble, N M; Tokas, R B; Biswas, A; Poswal, A K; Thakur, S; Bhattacharyya, D; Sahoo, N K; Sabharwal, S C, E-mail: nksahoo@barc.gov.i, E-mail: sahoonk@gmail.co [Spectroscopy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2010-02-03

    Titania-silica (TiO{sub 2}/SiO{sub 2}) optical multilayer structures have been conventionally deposited by reactive sputtering of metallic targets. In order to overcome the problems of arcing, target poisoning and low deposition rates encountered there, the application of oxide targets was investigated in this work with asymmetric bipolar pulsed dc magnetron sputtering. In order to evaluate the usefulness of this deposition methodology, an electric field optimized Fabry Perot mirror for He-Cd laser ({lambda} = 441.6 nm) spectroscopy was deposited and characterized. For comparison, this mirror was also deposited by the reactive electron beam (EB) evaporation technique. The mirrors developed by the two complementary techniques were investigated for their microstructural and optical reflection properties invoking atomic force microscopy, ellipsometry, grazing incidence reflectometry and spectrophotometry. From these measurements the layer geometry, optical constants, mass density, topography, surface and interface roughness and disorder parameters were evaluated. The microstructural properties and spectral functional characteristics of the pulsed dc sputtered multilayer mirror were found to be distinctively superior to the EB deposited mirror. The knowledge gathered during this study has been utilized to develop a 21-layer high-pass edge filter for radio photoluminescence dosimetry.

  11. Photocatalytic and photoelectrocatalytic degradation of the drug omeprazole on nanocrystalline titania films in alkaline media: Effect of applied electrical bias on degradation and transformation products.

    Science.gov (United States)

    Tantis, Iosif; Bousiakou, Leda; Frontistis, Zacharias; Mantzavinos, Dionissios; Konstantinou, Ioannis; Antonopoulou, Maria; Karikas, George-Albert; Lianos, Panagiotis

    2015-08-30

    Photocatalytic and photoelectrocatalytic degradation of the drug omeprazole has been studied in the presence of nanocrystalline titania films supported on glass slides or transparent FTO electrodes in alkaline environment. Its photocatalytic degradation rate was assessed by its UV absorbance and by HPLC, while its transformation products were analyzed by HR-LC-MS. Based on UV absorbance, omeprazole can be photocatalytically degraded at an average rate of 6.7×10(-4)min(-1) under low intensity UVA irradiation of 1.5mWcm(-2) in the presence of a nanoparticulate titania film. This corresponds to degradation of 1.4mg of omeprazole per gram of the photocatalyst per liter of solution per hour. The photodegradation rate can be accelerated in a photoelectrochemical cell by applying a forward bias. In this case, the maximum rate reached under the present conditions was 11.6×10(-4)min(-1) by applying a forward bias of +0.6V vs. Ag/AgCl. Four major transformation products were successfully identified and their profiles were followed by HR-LC-MS. The major degradation path includes the scission of the sulfoxide bridge into the corresponding pyridine and benzimidazole ring derivates and this is accompanied by the release of sulfate anions in the reaction mixture.

  12. Direct surface force measurements of polyelectrolyte multilayer films containing nanocrystalline cellulose.

    Science.gov (United States)

    Cranston, Emily D; Gray, Derek G; Rutland, Mark W

    2010-11-16

    Polyelectrolyte multilayer films containing nanocrystalline cellulose (NCC) and poly(allylamine hydrochloride) (PAH) make up a new class of nanostructured composite with applications ranging from coatings to biomedical devices. Moreover, these materials are amenable to surface force studies using colloid-probe atomic force microscopy (CP-AFM). For electrostatically assembled films with either NCC or PAH as the outermost layer, surface morphology was investigated by AFM and wettability was examined by contact angle measurements. By varying the surrounding ionic strength and pH, the relative contributions from electrostatic, van der Waals, steric, and polymer bridging interactions were evaluated. The ionic cross-linking in these films rendered them stable under all solution conditions studied although swelling at low pH and high ionic strength was inferred. The underlying polymer layer in the multilayered film was found to dictate the dominant surface forces when polymer migration and chain extension were facilitated. The precontact normal forces between a silica probe and an NCC-capped multilayer film were monotonically repulsive at pH values where the material surfaces were similarly and fully charged. In contrast, at pH 3.5, the anionic surfaces were weakly charged but the underlying layer of cationic PAH was fully charged and attractive forces dominated due to polymer bridging from extended PAH chains. The interaction with an anionic carboxylic acid probe showed similar behavior to the silica probe; however, for a cationic amine probe with an anionic NCC-capped film, electrostatic double-layer attraction at low pH, and electrostatic double-layer repulsion at high pH, were observed. Finally, the effect of the capping layer was studied with an anionic probe, which indicated that NCC-capped films exhibited purely repulsive forces which were larger in magnitude than the combination of electrostatic double-layer attraction and steric repulsion, measured for PAH

  13. Photocatalytic and photoelectrocatalytic degradation of the drug omeprazole on nanocrystalline titania films in alkaline media: Effect of applied electrical bias on degradation and transformation products

    Energy Technology Data Exchange (ETDEWEB)

    Tantis, Iosif [Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras (Greece); Bousiakou, Leda [Department of Physics and Astronomy, King Saud University, Riyadh (Saudi Arabia); Department of Automation Engineering, Technological Educational Institute of Pireaus, GR-12244 Athens (Greece); Frontistis, Zacharias; Mantzavinos, Dionissios [Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras (Greece); Konstantinou, Ioannis; Antonopoulou, Maria [Department of Environmental and Natural Resources Management, University of Patras, GR-30100 Agrinio (Greece); Karikas, George-Albert [Department of Medical Laboratories Technology, Technological Educational Institute of Athens, 12210 Athens (Greece); Lianos, Panagiotis, E-mail: lianos@upatras.gr [Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras (Greece); FORTH/ICE-HT, P.O. Box 1414, GR-26504 Patras (Greece)

    2015-08-30

    Highlights: • Photocatalytic and photoelectrocatalytic degradation of the proton pump omeprazole. • Improvement of photocatalysis rate by applying a moderate forward bias. • Highlighting of the advantages of photoelectrocatalysis in a straightforward manner. • HPLC and HR-LC–MS analysis of transformation products. - Abstract: Photocatalytic and photoelectrocatalytic degradation of the drug omeprazole has been studied in the presence of nanocrystalline titania films supported on glass slides or transparent FTO electrodes in alkaline environment. Its photocatalytic degradation rate was assessed by its UV absorbance and by HPLC, while its transformation products were analyzed by HR-LC–MS. Based on UV absorbance, omeprazole can be photocatalytically degraded at an average rate of 6.7 × 10{sup −4} min{sup −1} under low intensity UVA irradiation of 1.5 mW cm{sup −2} in the presence of a nanoparticulate titania film. This corresponds to degradation of 1.4 mg of omeprazole per gram of the photocatalyst per liter of solution per hour. The photodegradation rate can be accelerated in a photoelectrochemical cell by applying a forward bias. In this case, the maximum rate reached under the present conditions was 11.6 × 10{sup −4} min{sup −1} by applying a forward bias of +0.6 V vs. Ag/AgCl. Four major transformation products were successfully identified and their profiles were followed by HR-LC–MS. The major degradation path includes the scission of the sulfoxide bridge into the corresponding pyridine and benzimidazole ring derivates and this is accompanied by the release of sulfate anions in the reaction mixture.

  14. A Modified Thermal Treatment Method for the Up-Scalable Synthesis of Size-Controlled Nanocrystalline Titania

    OpenAIRE

    Aysar Sabah Keiteb; Elias Saion; Azmi Zakaria; Nayereh Soltani; Nura Abdullahi

    2016-01-01

    Considering the increasing demand for titania nanoparticles with controlled quality for various applications, the present work reports the up-scalable synthesis of size-controlled titanium dioxide nanocrystals with a simple and convenient thermal treatment route. Titanium dioxide nanocrystals with tetragonal structure were synthesized directly from an aqueous solution containing titanium (IV) isopropoxide as the main reactant, polyvinyl pyrrolidone (PVP) as the capping agent, and deionized wa...

  15. Naturally Produced Co/CoO Nanocrystalline Magnetic Multilayers: Structure and Inverted Hysteresis.

    Science.gov (United States)

    Santarossa, Francesca; Pappas, Spiridon D; Delimitis, Andreas; Sousanis, Andreas; Poulopoulos, Panagiotis

    2016-05-01

    Cobalt-based multilayers with excellent sequencing are grown via radiofrequency magnetron sputtering with the use of one Co target and natural oxidation. The Co layers are continuous, fully textured {111} and have the face centered cubic structure. At the end of deposition of each Co layer air is let to flow into the vacuum chamber via a fine (leak) valve. The top of Co is oxidized. The oxidized layers consist of cubic CoO crystallites. Near the film surface hexagonal Co(OH)2 is also detected. Magneto-optical Kerr effect hysteresis loops show in-plane magnetized films. The magnetic saturation field in the out-of-plane measurements is large exceeding 12 kOe. This observation supports indirectly the fact that Co is face centered cubic; if it was c-axis textured hexagonal the magnetocrystalline anisotropy would be large resulting in smaller values of the saturation field. As the Co-layer thickness decreases the in-plane loops show reduced remanence, slow approach to magnetic saturation and the out-of-plane loops show inverted hysteresis and/or crossing loop features with sizeable remanence. The effects are discussed with respect to the enhanced orbital magnetic moment of Co and the antiferromagnetic coupling between Co spins at the Co/CoO interface.

  16. Hydrogen sulfide conversion with nanophase titania

    Science.gov (United States)

    Beck, D.D.; Siegel, R.W.

    1996-08-20

    A process is described for disassociating H{sub 2}S in a gaseous feed using an improved catalytic material in which the feed is contacted at a temperature of at least about 275 C with a catalyst of rutile nanocrystalline titania having grain sizes in the range of from about 1 to about 100 nanometers. Other transition metal catalysts are disclosed, each of nanocrystalline material with grain sizes in the 1-100 nm range. 5 figs.

  17. Electrochemical behavior of nanocrystalline Ta/TaN multilayer on 316L stainless steel: Novel bipolar plates for proton exchange membrane fuel-cells

    Science.gov (United States)

    Alishahi, M.; Mahboubi, F.; Mousavi Khoie, S. M.; Aparicio, M.; Hübner, R.; Soldera, F.; Gago, R.

    2016-08-01

    Insufficient corrosion resistance and surface conductivity are two main issues that plague large-scale application of stainless steel (SS) bipolar plates in proton exchange membrane fuel cells (PEMFCs). This study explores the use of nanocrystalline Ta/TaN multilayer coatings to improve the electrical and electrochemical performance of polished 316L SS bipolar plates. The multilayer coatings have been deposited by (reactive) magnetron sputtering and characterized by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy. The electrochemical behavior of bare and coated substrates has been evaluated in simulated PEMFC working environments by potentiodynamic and potentiostatic polarization tests at ambient temperature and 80 °C. The results show that the Ta/TaN multilayer coating increases the polarization resistance of 316L SS by about 30 and 104 times at ambient and elevated temperatures, respectively. The interfacial contact resistance (ICR) shows a low value of 12 mΩ × cm2 before the potentiostatic test. This ICR is significantly lower than for the bare substrate and remains mostly unchanged after potentiostatic polarization for 14 h. In addition, the high contact angle (92°) with water for coated substrates indicates a hydrophobic character, which can improve the water management within the cell in PEMFC stacks.

  18. FEM numerical analysis of excimer laser induced modification in alternating multi-layers of amorphous and nano-crystalline silicon films

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.es [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Martin, E. [Dpto. Mecanica, Maquinas, Motores Termicos y Fluidos, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Stefanov, S. [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Alpuim, P. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Chiussi, S. [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer nc-Si:H is a material with growing importance for a large-area of nano-electronic, photovoltaic or biomedical devices. Black-Right-Pointing-Pointer UV-ELA technique causes a rapid heating that provokes the H{sub 2} desorption from the Si surface and bulk material. Black-Right-Pointing-Pointer Next, diffusion of P doped nc-Si films and eventually, for high energy densities would be possible to reach the melting point. Black-Right-Pointing-Pointer These multilayer structures consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) films deposited on SiO{sub 2}. Black-Right-Pointing-Pointer To optimize parameters involved in this processing, FEM numerical analysis of multilayer structures have been performed. Black-Right-Pointing-Pointer The numerical results are compared with exhaustive characterization of the experimental results. - Abstract: UV excimer laser annealing (UV-ELA) is an alternative annealing process that, during the last few years, has gained enormous importance for the CMOS nano-electronic technologies, with the ability to provide films and alloys with electrical and optical properties to fit the desired device performance. The UV-ELA of amorphous (a-) and/or doped nano-crystalline (nc-) silicon films is based on the rapid (nanoseconds) formation of temperature profiles caused by laser radiation that is absorbed in the material and lead to crystallisation, diffusion in solid or even in liquid phase. To achieve the desired temperature profiles and to optimize the parameters involved in the processing of hydrogenated nanocrystalline silicon (nc-Si:H) films with the UV-ELA, a numerical analysis by finite element method (FEM) of a multilayer structure has been performed. The multilayer structures, consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) layers, deposited on a glass substrate, has also been experimentally analyzed. Temperature profiles caused by 193 nm radiation with 25

  19. Preparation of Highly Crystalline TiO2 Nanostructures by Acid-assisted Hydrothermal Treatment of Hexagonal-structured Nanocrystalline Titania/Cetyltrimethyammonium Bromide Nanoskeleton

    Directory of Open Access Journals (Sweden)

    Sakai Hideki

    2010-01-01

    Full Text Available Abstract Highly crystalline TiO2 nanostructures were prepared through a facile inorganic acid-assisted hydrothermal treatment of hexagonal-structured assemblies of nanocrystalline titiania templated by cetyltrimethylammonium bromide (Hex-ncTiO2/CTAB Nanoskeleton as starting materials. All samples were characterized by X-ray diffraction (XRD and transmission electron microscopy (TEM. The influence of hydrochloric acid concentration on the morphology, crystalline and the formation of the nanostructures were investigated. We found that the morphology and crystalline phase strongly depended on the hydrochloric acid concentrations. More importantly, crystalline phase was closely related to the morphology of TiO2 nanostructure. Nanoparticles were polycrystalline anatase phase, and aligned nanorods were single crystalline rutile phase. Possible formation mechanisms of TiO2 nanostructures with various crystalline phases and morphologies were proposed.

  20. The structure and mechanical properties of multilayer nanocrystalline TiN/ZrN coatings obtained by vacuum-arc deposition

    Directory of Open Access Journals (Sweden)

    A.V. Demchyshyn

    2007-12-01

    Full Text Available TiN/ZrN multilayered condensates on BK-8 carbide tips substrates (62 HRC were produced by the vacuumarc deposition technique, using Ti and Zr plasma flows in reactive nitrogen gas medium with working pressure of 6.6·10–1 Pa. The TiN/ZrN multilayered condensates consist of TiN and ZrN sublayers, which have a thickness of ~100 nm, controlled by the processing parameters of the used deposition technique. The obtained coatings have hardness of 45 GPa and Young’s modulus of 320 GPa. The obtained results show that mechanical properties of such multilayered composites are considerably improved in comparison to those for the single-component coatings, TiN and ZrN. The dependence of hardness and Young’s modulus of the composites on sublayer thickness within a range of 100 nm was determined. The investigated structure and improved mechanical properties of the TiN/ZrN multilayered condensates would be very good platform for finding their industrial application, such as hard coatings with different purposes.

  1. Nanocrystalline-Si-dot multi-layers fabrication by chemical vapor deposition with H-plasma surface treatment and evaluation of structure and quantum confinement effects

    Directory of Open Access Journals (Sweden)

    Daisuke Kosemura

    2014-01-01

    Full Text Available 100-nm-thick nanocrystalline silicon (nano-Si-dot multi-layers on a Si substrate were fabricated by the sequential repetition of H-plasma surface treatment, chemical vapor deposition, and surface oxidation, for over 120 times. The diameter of the nano-Si dots was 5–6 nm, as confirmed by both the transmission electron microscopy and X-ray diffraction analysis. The annealing process was important to improve the crystallinity of the nano-Si dot. We investigated quantum confinement effects by Raman spectroscopy and photoluminescence (PL measurements. Based on the experimental results, we simulated the Raman spectrum using a phenomenological model. Consequently, the strain induced in the nano-Si dots was estimated by comparing the experimental and simulated results. Taking the estimated strain value into consideration, the band gap modulation was measured, and the diameter of the nano-Si dots was calculated to be 5.6 nm by using PL. The relaxation of the q ∼ 0 selection rule model for the nano-Si dots is believed to be important to explain both the phenomena of peak broadening on the low-wavenumber side observed in Raman spectra and the blue shift observed in PL measurements.

  2. Preparation and characterisation of novel thick sol-gel titania film photocatalysts.

    Science.gov (United States)

    Mills, Andrew; Elliott, Nicholas; Hill, George; Fallis, David; Durrant, James R; Willis, Richard L

    2003-05-01

    The preparation and characterization of thick (9 microns), clear, mechanically robust and photocatalytically active films of nanocrystalline anatase titania are described. XRD and SEM analysis show the films comprise 13 nm particles of anatase TiO2. Thin (54 nm) films of the 'paste' TiO2, along with sol-gel titania films made by a more traditional route are also prepared and characterised. All titania films mediate the photocatalytic destruction of stearic acid with a quantum yield of 0.0016 +/- 0.0003, using either 365 nm (i.e. BLB) or 254 nm (germicidal) light. P25 TiO2 films also appear to mediate the same process with a similar formal quantum efficiency. Of all the films tested, the thick paste TiO2 films are the most ideally suited for use with near UV light, for reasons which are discussed. All the titania films tested exhibit photoinduced superhydrophilicity.

  3. Structural, magnetic, and magneto-optical properties of nanocrystalline face centered cubic Co70Cr30/Pt multilayers with perpendicular magnetic anisotropy.

    Science.gov (United States)

    Papaioannou, E Th; Angelakeris, M; Poulopoulos, P; Tsiaoussis, I; Rüdt, C; Fumagalli, P; Flevaris, N K

    2007-12-01

    Co70Cr30 alloyed layers are combined with extremely thin Pt layers in order to produce novel face-centered-cubic multilayered films to be considered as a potential perpendicular magnetic recording medium. The films were grown on Si, glass and polyimide substrates by e-beam evaporation at a temperature slightly higher than room temperature. The multilayered structure of the films was verified by X-ray diffraction experiments. Plane-view transmission electron microscopy images have revealed the formation of very small grains in the range of 7-9 nm. Hysteresis loops as a function of temperature were recorded via the magneto-optic Kerr effect in the polar geometry configuration. The system exhibits perpendicular magnetic anisotropy, which enhances with decreasing temperature. Hysteresis loops with a squareness of 1 and a coercivity of 1.45 kOe were obtained at 10 K. Furthermore, complete magneto-optic spectra of the films are recorded, showing a strong magneto-optic enhancement in the ultraviolet region at around 4.5 eV.

  4. Reactive plasma synthesis of nanocrystalline ceramic oxides

    Science.gov (United States)

    Sreekumar, K. P.; Vijay, M.; Thiyagarajan, T. K.; Krishnan, K.; Ananthapadmanabhan, P. V.

    2010-02-01

    Reactive plasma synthesis is an attractive route to synthesize nanocrystalline materials. A 40 kW DC non-transferred arc plasma reactor has been designed and developed in our laboratory for synthesis of nanocrystalline materials. The main components of the plasma reactor include a 40 kW DC plasma generator or plasma torch, water-cooled reactor segment, product collection facility, DC power supply, cooling-water system and exhaust gas vent. The system has been used to synthesize nano-crystalline oxides of aluminium, titanium and zirconium. Aluminium metal powder was used as the starting material to synthesize alumina. The hydrides of Ti and Zr were used as the precursor for synthesis of nanocrystalline titania and zirconia respectively. The precursor powders were injected into the thermal plasma jet and were allowed to react with oxygen injected downstream the jet. The precursor powder particles were oxidized 'in-flight' to form nano-sized powder of the respective metal, which deposited on the walls of the reactor and collector assembly. Various analytical tools were used to characterized the products.

  5. Synthesis and Microstructure Evolution of Nano-Titania Doped Silicon Coatings

    Science.gov (United States)

    Moroz, N. A.; Umapathy, H.; Mohanty, P.

    2010-01-01

    The Anatase phase of Titania (TiO2) in nanocrystalline form is a well known photocatalyst. Photocatalysts are commercially used to accelerate photoreactions and increase photovoltaic efficiency such as in solar cells. This study investigates the in-flight synthesis of Titania and its doping into a Silicon matrix resulting in a catalyst-dispersed coating. A liquid precursor of Titanium Isopropoxide and ethanol was coaxially fed into the plasma gun to form Titania nanoparticles, while Silicon powder was externally injected downstream. Coatings of 75-150 μm thick were deposited onto flat coupons. Further, Silicon powder was alloyed with aluminum to promote crystallization and reduce the amorphous phase in the Silicon matrix. Dense coatings containing nano-Titania particles were observed under electron microscope. X-ray diffraction showed that both the Rutile and Anatase phases of the Titania exist. The influence of process parameters and aluminum alloying on the microstructure evolution of the doped coatings is analyzed and presented.

  6. Effective medium approximation for deeply subwavelength all-dielectric multilayers: when does it break down?

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Zhukovsky, Sergei; Andryieuski, Andrei;

    2016-01-01

    of the breakdown effect. Multilayer stacks are composed of alternating alumina and titania layers fabricated using atomic layer deposition. For light incident on such multilayers at angles near the total internal reflection, we observe pronounced differences in the reflectance spectra (up to 0.5) for structures...

  7. Nanocrystalline ceramic materials

    Science.gov (United States)

    Siegel, Richard W.; Nieman, G. William; Weertman, Julia R.

    1994-01-01

    A method for preparing a treated nanocrystalline metallic material. The method of preparation includes providing a starting nanocrystalline metallic material with a grain size less than about 35 nm, compacting the starting nanocrystalline metallic material in an inert atmosphere and annealing the compacted metallic material at a temperature less than about one-half the melting point of the metallic material.

  8. Synthesis of nanocrystalline rutile-phase titania at low temperatures

    OpenAIRE

    SANTOS, Jorge Gomes dos; Ogasawara,Tsuneharu; CORRÊA, Ronaldo Antonio

    2009-01-01

    Anatase and rutile are the predominant phases in titanium dioxide. In many cases, rutile stable phase is the desired product material, but at low temperatures methods of synthesis (aqueous route) produce metastable anatase as a major product that reverts to rutile only when heated up to 1000 °C. Calcination for obtaining rutile phase is the greatest energy demanding step for titanium dioxide production by the sulphate process, and is responsible for almost 60% of total energy consumption. In ...

  9. Design, Modeling and Optimization of a Piezoelectric Pressure Sensor based on a Thin-Film PZT Membrane Containing Nanocrystalline Powders

    National Research Council Canada - National Science Library

    Vahid Mohammadi; Mohammad Hossein Sheikhi

    2009-01-01

    ...^ thin film has been presented and then a pressure sensor based on multilayer thin-film PZT diaphragm contain of Lead Zirconate Titanate nanocrystalline powders was designed, modeled and optimized...

  10. Hemocompatibility of titania nanotube arrays.

    Science.gov (United States)

    Smith, Barbara S; Yoriya, Sorachon; Grissom, Laura; Grimes, Craig A; Popat, Ketul C

    2010-11-01

    Hemocompatibility is a key consideration for the long-term success of blood contacting biomaterials; hence, there is a critical need to understand the physiological response elicited from blood/nano-biomaterial interactions. In this study, we have investigated the adsorption of key blood serum proteins, in vitro adhesion and activation of platelets, and clotting kinetics of whole blood on titania nanotube arrays. Previous studies have demonstrated improved mesenchymal stem cell functionality, osteoblast phenotypic behavior, localized drug delivery, and the production of endothelial cell ECM on titania nanotube arrays. Furthermore, these titania nanotube arrays have elicited minimal levels of monocyte activation and cytokine secretion, thus exhibiting a very low degree of immunogenicity. Titania nanotube arrays were fabricated using anodization technique and the surface morphology was examined through scanning electron microscopy (SEM). The crystalline phases were identified using glancing angled X-ray diffraction (GAXRD). Nanoindentation and scratch tests were used to characterize the mechanical properties of titania nanotube arrays. The adsorption of key blood proteins (albumin, fibrinogen, and immunoglobulin-g) was evaluated using a micro-BCA assay and X-ray photoelectron spectroscopy (XPS). The adhesion and activation of platelets was investigated using live-cell staining, MTT assay, and SEM. Whole blood clotting kinetics was evaluated by measuring the free hemoglobin concentration, and SEM was used to visualize the clot formation. Our results indicate increased blood serum protein adsorption, platelet adhesion and activation, and whole blood clotting kinetics on titania nanotube arrays.

  11. Titania Deposition on PMR-15

    Science.gov (United States)

    Meador, Mary B.; Sutter, James K.; Pizem, Hillel; Gershevitz, Olga; Goffer, Yossi; Frimer, Aryeh A.; Sukenik, Chaim N.; Sampathkumaran, Uma; Milhet, Xavier; McIlwain, Alan

    2005-01-01

    The formation, degree of crystallinity and adherence of dense titania (TiO2) thin film coatings on a high-temperature polyimide resin (PMR-15) can be influenced by the chemical composition of the polymer surface. Furthermore, solution deposition conditions can be adjusted to provide additional control over the morphology and crystallinity of the titania films. Recipes for solution-based titania deposition that used a slowly-hydrolyzing titanium fluoride salt in the presence of boric acid as a fluoride scavenger allowed growth of films up to 750 nm thick in 22 h. By adjusting solution pH and temperature, either amorphous titania or oriented crystalline anatase films could be formed. Surface sulfonate groups enhance the adhesion of solution-deposited oxide thin film coatings. While most sulfonation procedures severely damaged the PMR-15 surface, the use of chlorosulfonic acid followed by hydrolysis of the installed chlorosulfonyl groups provided effective surface sulfonation without significant surface damage. In some cases, the oxide deposition solution caused partial hydrolysis of the polymer surface, which itself was sufficient to allow adhesion of the titania film through chelation of titanium ions by exposed benzoic acid groups on the polymer surface.

  12. Nanocrystalline ceramic materials

    Science.gov (United States)

    Siegel, R.W.; Nieman, G.W.; Weertman, J.R.

    1994-06-14

    A method is disclosed for preparing a treated nanocrystalline metallic material. The method of preparation includes providing a starting nanocrystalline metallic material with a grain size less than about 35 nm, compacting the starting nanocrystalline metallic material in an inert atmosphere and annealing the compacted metallic material at a temperature less than about one-half the melting point of the metallic material. 19 figs.

  13. Surface plasmon resonance in nanocrystalline gold-copper alloy films.

    Science.gov (United States)

    Hussain, S; Datta, Subhadeep; Roy, R K; Pal, A K

    2007-12-01

    Nanocrystalline Au(x)Cu(1-x) films were synthesized by depositing Cu/Au/Cu multilayer in nanocrystalline thin film form with requisite thickness of individual layers onto fused silica substrates by high pressure sputtering technique. The absorbance spectra showed only one surface plasmon peak for all the compositions with the exception that the peak position did not indicate gradual shift as gold concentration was increased. Peak position for the two compositions corresponding to the two superlattice structures, AuCu3 and AuCu, deviated significantly from linear variation. The experimental results have been discussed in light of the existing Mie theory and the Core-shell model.

  14. Tailoring Imprinted Titania Nanoparticles for Purines Recognition

    Directory of Open Access Journals (Sweden)

    Adnan Mujahid

    2015-01-01

    Full Text Available Molecular imprinted titania nanoparticles were developed for selective recognition of purines, for example, guanine and its final oxidation product uric acid. Titania nanoparticles were prepared by hydrolysis of titanium butoxide as precursor in the presence of pattern molecules. The morphology of synthesized nanoparticles is evaluated by SEM images. Recognition characteristics of imprinted titania nanoparticles are studied by exposing them to standard solution of guanine and uric acid, respectively. The resultant change in their concentration is determined by UV/Vis analysis that indicated imprinted titania nanoparticles possess high affinity for print molecules. In both cases, nonimprinted titania is taken as control to observe nonspecific binding interactions. Cross sensitivity studies suggested that imprinted titania is at least five times more selective for binding print molecules than competing analyte thus indicating its potential for bioassay of purines.

  15. D. C. Plasma-Sprayed Coatings of Nanostructured Alumina-Titania-Silica

    Institute of Scientific and Technical Information of China (English)

    蒋显亮; 刘敏

    2002-01-01

    Nanocrystalline powders of w(Al2O3) = 95%, w(TiO2) = 3%, and w(SiO2) = 2%,were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps ofball milling, slurry forming, spray drying, and heat treatment. D. C. plasma was used to spraythe agglomerated nanocrystalline 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. Exper-imental results show that the agglomerated nanocrystalline particles are spherical, with a size from (10~90)μm. The flow ability of the nanocrystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nanostructure. Un-like conventional plasma-sprayed coatings, no laminar layer could be found in the nanostructured coatings. Although the nanostructured coatings have a lower microhardness than conventional microstructured coatings, the toughness of the nanostructured ceramic coatings is significantly improved.

  16. 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...

  17. Preparation of nanoporous titania spherical nanoparticles

    Science.gov (United States)

    Shiba, Kota; Sato, Soh; Matsushita, Takayuki; Ogawa, Makoto

    2013-03-01

    Preparation of nanoporous titania particles from well-defined titania-octadecylamine (titania-ODA) hybrid spherical particles with 450 nm in size, which were prepared by the method reported previously (Chem. Commun., 2009, pp. 6851-6853 [39]; RSC Adv., 2012, vol. 2, pp. 1343-1349 [40]), was studied. ODA was removed by solvent extraction with acidic ethanol to obtain nanoporous titania particles and subsequent calcination led to the formation of nanoporous titania particles with the nanopore size ranging from 2 to 4 nm depending on the calcination temperature. The as-synthesized titania was amorphous and was transformed into anatase (at around 300 °C) and rutile (at around 600 °C) by the heat treatment. The phase transition behavior was discussed in comparison with that of as-synthesized titania-ODA particles without ODA removal. Spherical particles of titania-ODA hybrids with 70 nm in size were also transformed into nanoporous titania particles composed of anatase crystallites by the washing and calcination at 500 °C for 1 h.

  18. Creating bulk nanocrystalline metal.

    Energy Technology Data Exchange (ETDEWEB)

    Fredenburg, D. Anthony (Georgia Institute of Technology, Atlanta, GA); Saldana, Christopher J. (Purdue University, West Lafayette, IN); Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John (Ktech Corporation, Albuquerque, NM); Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  19. Deformation in nanocrystalline metals

    OpenAIRE

    Helena Van Swygenhoven; Julia R. Weertman

    2006-01-01

    It is now possible to synthesize polycrystalline metals made up of grains that average less than 100 nm in size. Such nanocrystalline metals contain a significant volume fraction of interfacial regions separated by nearly perfect crystals. The small sizes involved limit the conventional operation of dislocation sources and thus a fundamental question arises: how do these materials deform plastically? We review the current views on deformation mechanisms in nanocrystalline, face-centered cubic...

  20. Diffusion in nanocrystalline solids

    OpenAIRE

    Chadwick, Alan V.

    2016-01-01

    Enhanced atomic migration was an early observation from experimental studies into nanocrystalline solids. This contribution presents an overview of the available diffusion data for simple metals and ionic materials in nanocrystalline form. It will be shown that enhanced diffusion can be interpreted in terms of atomic transport along the interfaces, which are comparable to grain boundaries in coarse-grained analogues. However, the method of sample preparation is seen to play a major role in...

  1. Low temperature acetone detection by p-type nano-titania thin film: Equivalent circuit model and sensing mechanism

    Science.gov (United States)

    Bhowmik, B.; Dutta, K.; Hazra, A.; Bhattacharyya, P.

    2014-09-01

    Undoped nanocrystalline anatase p-type TiO2 thin film was deposited by sol-gel method on thermally oxidized p-Si (2-5 Ω cm, ) substrates. The thin film was characterized by X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) to confirm the formation of nanocrystalline anatase titania and to determine the crystallite size (∼7 nm). The resistive sensor structure was fabricated employing two lateral Pd electrodes on top of the TiO2 sensing layer. The developed sensor was tested in the temperature range of 50-200 °C for the detection of low ppm acetone (0.5-50 ppm). The maximum response of ∼115% was obtained at 150 °C with response/recovery time of 14 s/22 s at 50 ppm acetone (in air). Moreover, the sensors were capable of detecting acetone as low as 0.5 ppm with acceptable response magnitude. As titania acetone sensors are mostly n-TiO2 based, the acetone sensing mechanism for p-TiO2 is yet to be established authentically. To address the issue, an equivalent circuit model, based on the corresponding band diagram of nanocrystalline p-TiO2 with Pd electrode, was developed to describe the electron transfer mechanism through grain, grain boundary and Pd electrode under the influence of acetone vapor.

  2. Amorphous titania/carbon composite electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Vaughey, John T.; Jansen, Andrew; Joyce, Christopher D.

    2017-05-09

    An isolated salt comprising a compound of formula (H.sub.2X)(TiO(Y).sub.2) or a hydrate thereof, wherein X is 1,4-diazabicyclo[2.2.2]octane (DABCO), and Y is oxalate anion (C.sub.2O.sub.4.sup.-2), when heated in an oxygen-containing atmosphere at a temperature in the range of at least about 275.degree. C. to less than about 400.degree. C., decomposes to form an amorphous titania/carbon composite material comprising about 40 to about 50 percent by weight titania and about 50 to about 60 percent by weight of a carbonaceous material coating the titania. Heating the composite material at a temperature of about 400 to 500.degree. C. crystallizes the titania component to anatase. The titania materials of the invention are useful as components of the cathode or anode of a lithium or lithium ion electrochemical cell.

  3. Multilayer Networks

    CERN Document Server

    Kivelä, Mikko; Barthelemy, Marc; Gleeson, James P; Moreno, Yamir; Porter, Mason A

    2013-01-01

    Most real and engineered systems include multiple subsystems and layers of connectivity, and it is important to take such features into account to try to obtain a complete understanding of these systems. It is thus necessary to generalize "traditional" network theory by developing (and validating) a framework and associated tools to study multilayer systems in a comprehensive fashion. The origins of such efforts occurred several decades ago, but now the study of multilayer networks has become one of the major directions in network science. In this paper, we discuss the history of multilayer networks (and related concepts) and then review the exploding body of work on such networks. To unify the disparate terminology in the large body of recent work, we discuss a general framework for multilayer networks, construct a dictionary of terminology to relate the numerous existing concepts to each other, and provide a thorough discussion that compares, contrasts, and translates between related notions such as multila...

  4. Experimental Demonstration of Effective Medium Approximation Breakdown in Deeply Subwavelength All-Dielectric Multilayers

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Andryieuski, Andrei; Takayama, Osamu;

    2015-01-01

    stacks are composed of alternating alumina and titania layers fabricated using atomic layer deposition. For light incident on such multilayers at angles near the total internal reflection, we observe pronounced differences in the reflectance spectra for structures with 10- vs 20-nm thick layers, as well...

  5. Powder-based synthesis of nanocrystalline material components for structural application. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ilyuschenko, A.F.; Ivashko, V.S.; Okovity, V.A. [Powder Metallurgy Research Inst., Minsk (Belarus)] [and others

    1998-12-01

    Hydroxiapate spray coatings and substrates for implant production as well as multilayered metal ceramic coatings from nanocrystalline materials are a subject of the investigation. The work aims at the improvement of quality of said objects. This study has investigated the processes of hydroxiapatite powder production. Sizes, shapes and relief of initial HA powder surface are analyzed using SEM and TEM. Modes of HA plasma spraying on a substrate from titanium and associated compositions of traditional and nanocrystalline structure are optimized. The quality of the sprayed samples are studied using X-ray phase analysis and metallographic analysis. The results of investigations of bioceramic coating spraying on titanium are theoretically generalized, taking into account obtained experimental data. The results of investigations of ion-beam technology are presented for spraying multilayered coatings consisting of alternating metal-ceramic layers of nanocrystalline structure.

  6. Water disinfection through photoactive modified titania.

    Science.gov (United States)

    Sethi, Diptipriya; Pal, Ajoy; Sakthivel, Ramasamy; Pandey, Sony; Dash, Tapan; Das, Trupti; Kumar, Rohit

    2014-01-05

    TiO(2), N-TiO(2) and S-TiO(2) samples have been prepared by various chemical methods. These samples were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), Laser Raman spectrometer, UV-Visible spectrophotometer, field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). X-ray powder diffraction study reveals that all three samples are single anatase phase of titania and the crystallinity of titania decreases with sulphur doping whereas nitrogen doping does not affect it. UV-Visible (diffuse) reflectance spectra shows that doping of titania with nitrogen and sulphur shift the absorption edge of titania from ultraviolet to visible region. XPS study confirms that both nitrogen and sulphur are well doped in the titania lattice. It is observed that nitrogen occupies at both substitutional and interstitial position in the lattice of titania. FE-SEM and TEM studies demonstrate that the particles are below 50nm range. It is found that S and N doping of titania increased its water disinfection property in the order TiO(2)UV-Visible light irradiation.

  7. Synthesis and Characterization of Multilayered Diamond Coatings for Biomedical Implants

    Directory of Open Access Journals (Sweden)

    Leigh Booth

    2011-05-01

    Full Text Available With incredible hardness and excellent wear-resistance, nanocrystalline diamond (NCD coatings are gaining interest in the biomedical community as articulating surfaces of structural implant devices. The focus of this study was to deposit multilayered diamond coatings of alternating NCD and microcrystalline diamond (MCD layers on Ti-6Al-4V alloy surfaces using microwave plasma chemical vapor deposition (MPCVD and validate the multilayer coating’s effect on toughness and adhesion. Multilayer samples were designed with varying NCD to MCD thickness ratios and layer numbers. The surface morphology and structural characteristics of the coatings were studied with X-ray diffraction (XRD, Raman spectroscopy, and atomic force microscopy (AFM. Coating adhesion was assessed by Rockwell indentation and progressive load scratch adhesion tests. Multilayered coatings shown to exhibit the greatest adhesion, comparable to single-layered NCD coatings, were the multilayer samples having the lowest average grain sizes and the highest titanium carbide to diamond ratios.

  8. Deformation in nanocrystalline metals

    Directory of Open Access Journals (Sweden)

    Helena Van Swygenhoven

    2006-05-01

    Full Text Available It is now possible to synthesize polycrystalline metals made up of grains that average less than 100 nm in size. Such nanocrystalline metals contain a significant volume fraction of interfacial regions separated by nearly perfect crystals. The small sizes involved limit the conventional operation of dislocation sources and thus a fundamental question arises: how do these materials deform plastically? We review the current views on deformation mechanisms in nanocrystalline, face-centered cubic metals based on insights gained by atomistic computer simulations. These insights are discussed with reference to recent striking experimental observations that can be compared with predictions made by the simulations.

  9. Nanocrystalline and Nanoporous Ceramics

    NARCIS (Netherlands)

    Verweij, Henk

    1996-01-01

    Nanocrystalline and nanoporous ceramics, renowned for their special transport properties, have typical applications in the fields of energy, the environment, and separation technology. One example is a solid oxide fuel cell, where an anode with improved characteristics was obtained by an optimized n

  10. Nanocrystalline Heterojunction Materials

    Science.gov (United States)

    Elder, Scott H.; Su, Yali; Gao, Yufei; Heald, Steve M.

    2004-02-03

    Mesoporous nanocrystalline titanium dioxide heterojunction materials and methods of making the same are disclosed. In one disclosed embodiment, materials comprising a core of titanium dioxide and a shell of a molybdenum oxide exhibit a decrease in their photoadsorption energy as the size of the titanium dioxide core decreases.

  11. Precise size control over ultrafine rutile titania nanocrystallites in hierarchical nanotubular silica/titania hybrids with efficient photocatalytic activity.

    Science.gov (United States)

    Gu, Yuanqing; Huang, Jianguo

    2013-08-12

    Hierarchical-structured nanotubular silica/titania hybrids incorporated with particle-size-controllable ultrafine rutile titania nanocrystallites were realized by deposition of ultrathin titania sandwiched silica gel films onto each nanofiber of natural cellulose substances (e.g., common commercial filter paper) and subsequent flame burning in air. The rapid flame burning transforms the initially amorphous titania into rutile phase titania, and the silica gel films suppress the crystallite growth of rutile titania, thereby achieving nano-precise size regulation of ultrafine rutile titania nanocrystallites densely embedded in the silica films of the nanotubes. The average diameters of these nanocrystallites are adjustable in a range of approximately 3.3-16.0 nm by a crystallite size increment rate of about 2.4 nm per titania deposition cycle. The silica films transfer the electrons activated by crystalline titania and generate catalytic reactive species at the outer surface. The size-tuned ultrafine rutile titania nanocrystallites distributed in the unique hierarchical networks significantly improve the photocatalytic performance of the rutile phase titania, thereby enabling a highly efficient photocatalytic degradation of the methylene blue dye under ultraviolet light irradiation, which is even superior to the pure anatase-titania-based materials. The facile stepwise size control of the rutile titania crystallites described here opens an effective pathway for the design and preparation of fine-nanostructured rutile phase titania materials to explore potential applications.

  12. Synthesis of Cerium-Doped Titania Nanoparticles and Nanotubes.

    Science.gov (United States)

    Cao, Wei; Suzuki, Takuya; Elsayed-Ali, Hani E; Abdel-Fattah, Tarek M

    2015-03-01

    Cerium-doped titania nanoparticles and nanotubes were synthesized via hydrothermal processes. X-Ray Diffraction revealed that cerium-doped titania nanoparticles have an anatase crystal structure, while cerium-doped titania nanotubes have an H2Ti3O7-type structure. Scanning electron microscopy and high resolution transmission electron microscopy showed that both types of titania are well crystallized with relatively uniform size distribution. The photocatalytic degradation of methylthioninium chloride known as methylene blue dye was tested and both cerium-doped titania nanoparticles and nanotubes. The preliminary photocatalytic degradation of Methylene Blue data showed significantly improved visible light photocatalytic activities as compared to commercial titania powders.

  13. Effect of annealing temperature on titania nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, K., E-mail: sanjaymani367@gmail.com; Arumugam, S., E-mail: sanjaymani367@gmail.com [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli-620024 (India); Chandrasekaran, G. [Department of Physics, Pondicherry University, Pondicherry-605014 (India)

    2014-04-24

    Titania polycrystalline samples are prepared by using sol-gel route hydrolyzing a alkoxide titanium precursor under acidic conditions. The as prepared samples are treated with different calcination temperatures. The anatase phase of titania forms when treated below 600°C, above that temperature the anatase phase tends to transform into the rutile phase of titania. The experimental determination of average grain size, phase formation, lattice parameters and the crystal structures of titania samples at different calcinations is done using X-ray diffraction (XRD). Fourier Transform Infra-red Spectroscopy (FTIR), UV-vis-NIR spectroscopy and Scanning Electron Microscopy (SEM) and Energy Dispersive Analysis X-ray are used to characterize the samples to bring impact on the respective properties.

  14. Osteoblast differentiation with titania and titania-silica-coated titanium fiber meshes.

    NARCIS (Netherlands)

    Meretoja, V.V.; Ruijter, A.E. de; Peltola, T.; Jansen, J.A.; Narhi, T.O.

    2005-01-01

    Two surface-reactive sol-gel coatings, namely titania (TiO2) and a mixture of titania and silica (TiSi), were applied to titanium fiber meshes. Differentiation of rat bone marrow stromal cells toward an osteogenic phenotype with coated and uncoated (cpTi) substrates was compared. The amount of DNA i

  15. Silica-titania composite aerogel photocatalysts by chemical liquid deposition of titania onto nanoporous silica scaffolds.

    Science.gov (United States)

    Zu, Guoqing; Shen, Jun; Wang, Wenqin; Zou, Liping; Lian, Ya; Zhang, Zhihua

    2015-03-11

    Silica-titania composite aerogels were synthesized by chemical liquid deposition of titania onto nanoporous silica scaffolds. This novel deposition process was based on chemisorption of partially hydrolyzed titanium alkoxides from solution onto silica nanoparticle surfaces and subsequent hydrolysis and condensation to afford titania nanoparticles on the silica surface. The titania is homogeneously distributed in the silica-titania composite aerogels, and the titania content can be effectively controlled by regulating the deposition cycles. The resultant composite aerogel with 15 deposition cycles possessed a high specific surface area (SSA) of 425 m(2)/g, a small particle size of 5-14 nm, and a large pore volume and pore size of 2.41 cm(3)/g and 18.1 nm, respectively, after heat treatment at 600 °C and showed high photocatalytic activity in the photodegradation of methylene blue under UV-light irradiation. Its photocatalytic activity highly depends on the deposition cycles and heat treatment. The combination of small particle size, high SSA, and enhanced crystallinity after heat treatment at 600 °C contributes to the excellent photocatalytic property of the silica-titania composite aerogel. The higher SSAs compared to those of the reported titania aerogels (aerogels promising candidates as photocatalysts.

  16. Electrochemical biosensing based on polypyrrole/titania nanotube hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yibing, E-mail: ybxie@seu.edu.cn; Zhao, Ye

    2013-12-01

    The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. - Graphical abstract: The schematic diagram presents the fabrication of glucose oxidase modified polypyrrole/titania (GOD-PPy/TiO{sub 2}) nanotube enzyme electrode for biosensing application. - Highlights: • Hydrophilic polypyrrole/titania nanotube hybrid is well used as biosensing substrate. • Polypyrrole promotes GOD immobilization on titania nanotubes via glutaraldehyde. • GOD-polypyrrole/titania enzyme electrode shows good bioelectrocatalytic reactivity.

  17. Photoactive transparent nano-crystalline glass-ceramic for remazole red dye degradation

    Energy Technology Data Exchange (ETDEWEB)

    Gad-Allah, Tarek A., E-mail: tareqabdelshafy@yahoo.ca [Water Pollution Research Department, National Research Centre, Cairo 12311 (Egypt); Margha, Fatma H. [Department of Glass Research, National Research Centre, Cairo 12311 (Egypt)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Preparation and characterization of novel transparent nanocrystalline glass-ceramic. ► Precipitation of photoactive phases by using controlled heat-treatment. ► Conservation of transparency along with photoactivity. ► Using the prepared nanocrystalline glass-ceramic in water purification. -- Abstract: Transparent glass ceramic material was prepared from alkali-borosilicate glass containing titania by proper heat treatment scheme. The prepared samples were characterized using differential thermal analysis, X-ray diffraction, transmission electron microscope, selected area electron diffraction and UV–visible spectroscopy. The applied heat treatment program allowed the crystallization of nano-crystalline anatase, rutile, barium titanate, titanium borate and silicate phases while maintaining the transparency. The precipitated nano-crystalline anatase and rutile phases were responsible for the observed high photocatalytic activity of the prepared samples. Samples of 24.29 and 32.39 TiO{sub 2} wt% showed better efficiency for the decolorization of remazole red dye compared with commercial-TiO{sub 2} used in preparation of glass-ceramic. The reuse of prepared glass-ceramic photocatalyst with nearly same efficiency for different times was also proved.

  18. Removal of cationic Rhodamine-B dye using nano-titania with anatase crystalline structure and kinetic analysis of the photocatalytic reaction

    Science.gov (United States)

    Zhang, Dongfang

    2013-01-01

    Heterogeneous photocatalytic removal of Rhodamine-B (RhB) dye from liquid phase was done using anatase-phase nanocrystalline TiO2 synthesized via a modified sol-gel process. The anatase-phase nanocrystalline TiO2 was characterized using various analytical techniques including XRD, UV-vis DRS, PL, and FTIR to investigate its phase composition and structure, nanocrystalline size, band gap energy, photoluminescence and surface properties of the prepared systems. The photocatalytic discoloration efficiency of anatase-phase nanocrystalline titania was investigated by monitoring the decomposition of RhB dye as target compounds in an aqueous solution. The results showed that the as-prepared anatase-phase nanocrystalline TiO2 was excellent for degradation of RhB molecule, and the crystallite size, excitonic PL and surface hydroxyl content have intimate relationship with the decomposition efficiency of RhB. The reaction mechanism was proposed and the results demonstrate that the role of direct photolysis on RhB dye degradation can be neglected. Meanwhile, the Langmuir-Hinshelwood kinetic model describes the photodecay date of RhB in consistent with a first order powder law and thus photocatalytic oxidation reaction followed a pseudo-first-order kinetics.

  19. Study of the conditions affecting dye adsorption on titania films and of their effect on dye photodegradation rates.

    Science.gov (United States)

    Strataki, Nikoleta; Bekiari, Vlasoula; Lianos, Panagiotis

    2007-07-31

    Nanocrystalline titania films have been deposited on glass slides by the sol-gel technique in the presence of surfactant, which plays the role of template of the nanostructure. Several different dyes, both anionic and cationic, have been adsorbed on these films from aqueous solutions. Some of these dyes were adsorbed at large quantities some at lower quantities. Some of them were adsorbed in monomeric form and others formed aggregates. Aggregates are easily distinguished by absorption spectrophotometry, since absorption of light is observed at a different wavelength than monomer absorption in a dilute solution. In all cases, aggregation demonstrated a hypsochromic shift, indicating repulsive interactions, which are justified in view of the fact that titania surface is charged and that adsorbed molecules are aligned in parallel. The above titania films are hydroxylated. Therefore, cationic dyes were readily adsorbed. Anionic dyes could be adsorbed only from aqueous solutions brought at low pH. Photodegradation rates of adsorbed dyes were generally fast since these films are efficient photocatalysts. Nevertheless, photodegradation of an adsorbed dye was faster when the quantity of the dye was smaller. When the adsorbed dyes formed aggregates, aggregation had adverse effect on photodegradation rates.

  20. In-situ construction of three-dimensional titania network on Ti foil toward enhanced performance of flexible dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rui, Yichuan [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Wang, Yuanqiang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Zhang, Qinghong, E-mail: zhangqh@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Chi, Qijin; Zhang, Minwei [Department of Chemistry, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Wang, Hongzhi; Li, Yaogang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Hou, Chengyi, E-mail: chehou@kemi.dtu.dk [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Department of Chemistry, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark)

    2016-09-01

    Graphical abstract: - Highlights: • Three-dimensional titania network was in-situ constructed on Ti foil via sequential acid and hydrogen peroxide treatments. • All-flexible DSSCs based on the treated Ti foil showed significantly improved energy conversion efficiency. • Large-area flexible DSSCs exhibited good bending-stability due to the existence of the three-dimensional titania network. - Abstract: Three-dimensional titania network was in-situ constructed on Ti foil via sequential acid and hydrogen peroxide treatments. The titania network was pure anatase phase and homogeneously covered on the titanium grain surface, which largely enhanced the roughness of the Ti foil. The as-received Ti foil and the treated one were used as the flexible substrates of DSSCs, and energy conversion efficiencies of 3.74% and 4.98% were obtained, respectively. Such remarkable increment can be ascribed to the good electrical contact between the nanocrystalline TiO{sub 2} and the Ti foil, the improved electron percolation pathways and recombination inhibition of electrons in Ti substrate with triiodide ions in electrolyte. Flexible DSSCs based on the treated Ti foil showed relatively good mechanical stability, which exhibited 97.3% retention of the initial efficieny after twenty consecutive bending.

  1. In-situ construction of three-dimensional titania network on Ti foil toward enhanced performance of flexible dye-sensitized solar cells

    Science.gov (United States)

    Rui, Yichuan; Wang, Yuanqiang; Zhang, Qinghong; Chi, Qijin; Zhang, Minwei; Wang, Hongzhi; Li, Yaogang; Hou, Chengyi

    2016-09-01

    Three-dimensional titania network was in-situ constructed on Ti foil via sequential acid and hydrogen peroxide treatments. The titania network was pure anatase phase and homogeneously covered on the titanium grain surface, which largely enhanced the roughness of the Ti foil. The as-received Ti foil and the treated one were used as the flexible substrates of DSSCs, and energy conversion efficiencies of 3.74% and 4.98% were obtained, respectively. Such remarkable increment can be ascribed to the good electrical contact between the nanocrystalline TiO2 and the Ti foil, the improved electron percolation pathways and recombination inhibition of electrons in Ti substrate with triiodide ions in electrolyte. Flexible DSSCs based on the treated Ti foil showed relatively good mechanical stability, which exhibited 97.3% retention of the initial efficieny after twenty consecutive bending.

  2. Low-temperature fabrication of TiO2 nanocrystalline film electrodes for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shan, G.; Lee, K.E.; Charboneau, C.; Demopoulos, G.P.; Gauvin, R. [McGill Univ., Montreal, PQ (Canada). Dept. of Materials Engineering; Savadogo, O. [Ecole Polytechnique de Montreal, PQ (Canada). Dept. de Genie Chimique

    2008-07-01

    Dye-sensitized solar cells (DSSCs) have the potential to render solar energy widely accessible. The deposition of titania nano-crystalline powders on a substrate is an important step in the manufacture of the DSSC. The deposition forms a mesoporous thin film that is followed by thermal treatment and sensitization. Usually titania films are deposited on glass by screen printing and then annealed at temperatures as high as 530 degrees C to provide a good electrical contact between the semiconductor particles and crystallization of the anatase phase. Several research and development efforts have focused on the deposition of titania film on flexible plastic substrates that will simplify the whole manufacturing process in terms of flexibility, weight, application and cost. Lower temperature processing is needed for the preparation of plastic-based titania film electrodes, but this has proven to be counterproductive when it comes to the cell's conversion efficiency. This paper presented a comprehensive evaluation of the different coating and annealing techniques at low temperature as well as important processing factors for improvement. To date, these techniques include pressing, hydrothermal process, electrodeposition, electrophoretic deposition, microwave or UV irradiation, and lift-off technique.

  3. Magnetic multilayer structure

    Energy Technology Data Exchange (ETDEWEB)

    Herget, Philipp; O' Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang; Webb, Bucknell C.

    2017-03-21

    A mechanism is provided for an integrated laminated magnetic device. A substrate and a multilayer stack structure form the device. The multilayer stack structure includes alternating magnetic layers and diode structures formed on the substrate. Each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by a diode structure.

  4. Magnetic multilayer structure

    Science.gov (United States)

    Herget, Philipp; O'Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang; Webb, Bucknell C.

    2016-07-05

    A mechanism is provided for an integrated laminated magnetic device. A substrate and a multilayer stack structure form the device. The multilayer stack structure includes alternating magnetic layers and diode structures formed on the substrate. Each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by a diode structure.

  5. Titania nanotube array based photovoltaic cells

    Science.gov (United States)

    Yip, C. T.; Cheung, K. Y.; Djurišić, A. B.; Chan, W. K.

    2007-09-01

    It has been shown that dye sensitized solar cells (DSSCs) based on porous titanium dioxide (titania) layers have efficiencies exceeding 10%. Although porous structure has the advantage of large surface area for light harvesting, electron transport through the random nanoparticle network forming a porous film results in electron mobilities which are two orders of magnitude lower compared to the single crystal materials. Therefore, considerable efforts have been made to fabricate DSSC based on one dimensional nanostructures, such as nanowires or nanotubes. Titania nanotube arrays are typically made by anodization of titanium, followed by annealing to improve crystallinity. In this work, we investigated the influence of annealing temperature and annealing atmosphere on the crystal structure, the electron transport, and the solar cell performance of titania nanotube arrays. The titania nanotube arrays were prepared from electrochemically anodized titanium foils and their morphology and crystal structure were characterized by scanning electron microscopy and transmission electron microscopy. The crystal phases and the compositions of nanotube arrays were further investigated by X-ray diffraction for different annealing temperatures and X-ray photoelectron spectroscopy for different annealing atmospheres. For optimal annealing conditions, the short circuit current density of 4.27 mA/cm2 and power conversion efficiency of 1.30% could be achieved under AM 1.5 simulated solar irradiation for 2 μm long nanotubes.

  6. Titania nanotube arrays: Interfaces for implantable devices

    Science.gov (United States)

    Smith, Barbara Symie

    For the 8--10% of Americans (20--25 million people) that have implanted biomedical devices, biomaterial failure and the need for revision surgery are critical concerns. The major causes for failure in implantable biomedical devices promoting a need for re-implantation and revision surgery include thrombosis, post-operative infection, immune driven fibrosis and biomechanical failure. The successful integration of long-term implantable devices is highly dependent on the early events of tissue/biomaterial interaction, promoting either implant rejection or a wound healing response (extracellular matrix production and vasculature). Favorable interactions between the implant surface and the respective tissue are critical for the long-term success of any implantable device. Recent studies have shown that material surfaces which mimic the natural physiological hierarchy of in vivo tissue may provide a possible solution for enhancing biomaterial integration, thus preventing infection and biomaterial rejection. Titania nanotube arrays, fabricated using a simple anodization technique, provide a template capable of promoting altered cellular functionality at a hierarchy similar to that of natural tissue. This work focuses on the fabrication of immobilized, vertically oriented and highly uniform titania nanotube arrays to determine how this specific nano-architecture affects skin cell functionality, hemocompatibility, thrombogenicity and the immune response. The results in this work identify enhanced dermal matrix production, altered hemocompatibility, reduced thrombogenicity and a deterred immune response on titania nanotube arrays. This evidences promising implications with respect to the use of titania nanotube arrays as beneficial interfaces for the successful implantation of biomedical devices.

  7. Titania Photocatalysis beyond Recombination: A Critical Review

    Directory of Open Access Journals (Sweden)

    Bunsho Ohtani

    2013-11-01

    Full Text Available This short review paper shows the significance of recombination of a photoexcited electron and a hole in conduction and valence bands, respectively, of a titania photocatalyst, since recombination has not yet been fully understood and has not been evaluated adequately during the past several decades of research on heterogeneous photocatalysis.

  8. Biological applications of nanocrystalline diamond

    OpenAIRE

    Williams, Oliver; Daenen, Michael; Haenen, Ken

    2007-01-01

    Nanocrystalline diamond films have generated substantial interest in recent years due to their low cost, extreme properties and wide application arena. Diamond is chemically inert, has a wide electrochemical window and is stable in numerous harsh environments. Nanocrystalline diamond has the advantage of being readily grown on a variety of substrates at very low thickness, resulting in smooth conformal coatings with high transparency. These films can be doped from highly insulating to metalli...

  9. Dislocation Dynamics in Nanocrystalline Nickel

    OpenAIRE

    Shan, Z. W.; Wiezorek, J. M. K.; Stach, E. A.; Follstaedt, D. M.; Knapp, J. A.; Mao, S. X.

    2007-01-01

    It is believed that the dynamics of dislocation processes during the deformation of nanocrystalline materials can only be visualized by computational simulations. Here we demonstrate that observations of dislocation processes during the deformation of nanocrystalline Ni with grain sizes as small as 10 nm can be achieved by using a combination of in situ tensile straining and high-resolution transmission electron microscopy. Trapped unit lattice dislocations are observed in strained grains...

  10. Experimental Demonstration of Effective Medium Approximation Breakdown in Deeply Subwavelength All-Dielectric Multilayers

    CERN Document Server

    Zhukovsky, Sergei V; Takayama, Osamu; Shkondin, Evgeniy; Malureanu, Radu; Jensen, Flemming; Lavrinenko, Andrei V

    2015-01-01

    We experimentally demonstrate the effect of anomalous breakdown of the effective medium approximation in all-dielectric deeply subwavelength thickness ($d \\sim\\lambda/160-\\lambda/30$) multilayers, as recently predicted theoretically [H.H. Sheinfux et al., Phys. Rev. Lett. 113, 243901 (2014)]. Multilayer stacks are composed of alternating alumina and titania layers fabricated using atomic layer deposition. For light incident on such multilayers at angles near the total internal reflection we observe pronounced differences in the reflectance spectra for structures with 10-nm versus 20-nm thick layers, as well as for structures with different layers ordering, contrary to the predictions of the effective medium approximation. The reflectance difference can reach values up to 0.5, owing to the chosen geometrical configuration with an additional resonator layer employed for the enhancement of the effect. Our results are important for the development of new high-precision multilayer ellipsometry methods and schemes,...

  11. Nanocrystalline diamond films for biomedical applications

    DEFF Research Database (Denmark)

    Pennisi, Cristian Pablo; Alcaide, Maria

    2014-01-01

    Nanocrystalline diamond films, which comprise the so called nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD), represent a class of biomaterials possessing outstanding mechanical, tribological, and electrical properties, which include high surface smoothness, high corrosion re...

  12. Comparative study of titania nanoparticles and nanotubes as antibacterial agents

    Science.gov (United States)

    Jing, Zhihong; Guo, Daojun; Wang, Weihua; Zhang, Shufang; Qi, Wei; Ling, Baoping

    2011-09-01

    Anatase titania nanoparticles with a high surface area (about 587.7 m 2/g) were synthesized by sol-gel method using isobutyl alcohol as solvent, and then anatase titania nanotubes with needlelike shape, which had diameters of about 5 nm and wall thickness of about 1 nm, could be obtained by microwave process using the above titania nanoparticles as precursors. Both titania nanoparticles and nanotubes were characterized through X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, photoluminescence spectroscopy and nitrogen adsorption-desorption isotherm technique. The antibacterial activities of both titania nanoparticles and nanotubes against Escherichia coli ( E. coli) were developed by quantification and qualitative ways, e.g. microcalorimetric method and disk diffusion method. At the same time, their antibacterial activities against E. coli were also investigated in dark and under UV irradiation. As a result, both the titania nanoparticles and nanotubes had good antibacterial activities against E. coli due to their low inhibitory concentration and large diameter of antibacterial circle. In addition, the titania nanoparticles displayed higher antibacterial activities than those of the titania nanotubes under UV irradiation, though they presented similar antibacterial activities in dark. The differences in antibacterial activities between titania nanoparticles and nanotubes might be attributed to the changes of their microstructure in our works.

  13. 离子液体-水的混合溶剂中,合成条件对纳米TiO2结晶度的影响%Effect of Synthesis Conditions on Crystallinity of Nano Titania in Mixture Solvent of Ionic Liquid and Water

    Institute of Scientific and Technical Information of China (English)

    闫智英; 郑文君

    2006-01-01

    The nanocrystalline TiO2 was prepared in mixture solvent of ionic liquid (1-ethyl-3-methyl -imidazole acetate, EmIm+AcO-) and water by sol-gel low temperature hydrothermal treatment of tetrabutyl titanate. X-ray diffraction (XRD), transmission electron microscope (TEM), and Automatic nitrogen adsorption measurement techniques were employed to characterize the final products. The influences of various hydrothermal conditions,such as the amount of ionic liquid, reaction temperature and time, on the crystallinity of titania were investigated.Crystallinity was evaluated by crystallite size. The results showed that the crystallinity of sample prepared in mixture solvent is higher than that of sample from pure water; also, the size and crystallinity of titania particle can be controlled by alteration of the amount of ionic liquid. In addition, in the presence of ionic liquid, highly crystalline titania could be obtained at relatively low temperature and shorter time.

  14. Sustainable steric stabilization of colloidal titania nanoparticles

    Science.gov (United States)

    Elbasuney, Sherif

    2017-07-01

    A route to produce a stable colloidal suspension is essential if mono-dispersed particles are to be successfully synthesized, isolated, and used in subsequent nanocomposite manufacture. Dispersing nanoparticles in fluids was found to be an important approach for avoiding poor dispersion characteristics. However, there is still a great tendency for colloidal nanoparticles to flocculate over time. Steric stabilization can prevent coagulation by introducing a thick adsorbed organic layer which constitutes a significant steric barrier that can prevent the particle surfaces from coming into direct contact. One of the main features of hydrothermal synthesis technique is that it offers novel approaches for sustainable nanoparticle surface modification. This manuscript reports on the sustainable steric stabilization of titanium dioxide nanoparticles. Nanoparticle surface modification was performed via two main approaches including post-synthesis and in situ surface modification. The tuneable hydrothermal conditions (i.e. temperature, pressure, flow rates, and surfactant addition) were optimized to enable controlled steric stabilization in a continuous fashion. Effective post synthesis surface modification with organic ligand (dodecenyl succinic anhydride (DDSA)) was achieved; the optimum surface coating temperature was reported to be 180-240 °C to ensure DDSA ring opening and binding to titania nanoparticles. Organic-modified titania demonstrated complete change in surface properties from hydrophilic to hydrophobic and exhibited phase transfer from the aqueous phase to the organic phase. Exclusive surface modification in the reactor was found to be an effective approach; it demonstrated surfactant loading level 2.2 times that of post synthesis surface modification. Titania was also stabilized in aqueous media using poly acrylic acid (PAA) as polar polymeric dispersant. PAA-titania nanoparticles demonstrated a durable amorphous polymeric layer of 2 nm thickness. This

  15. Titania-Silica Materials for Enhanced Photocatalysis.

    Science.gov (United States)

    Rico-Santacruz, Marisa; Serrano, Elena; Marcì, Giuseppe; García-López, Elisa I; García-Martínez, Javier

    2015-12-01

    Mesoporous titania-organosilica nanoparticles comprised of anatase nanocrystals crosslinked with organosilica moieties have been prepared by direct co-condensation of a titania precursor, tetrabuthylortotitanate (TBOT), with two organosilica precursors, 1,4-bis(triethoxysilyl) benzene (BTEB) and 1,2-bis(triethoxysilyl) ethane (BTEE), in mild conditions and in the absence of surfactant. These hybrid materials show both high surface areas (200-360 m(2)  g(-1) ) and pore volumes (0.3 cm(3)  g(-1) ) even after calcination, and excellent photoactivity in the degradation of rhodamine 6G and in the partial oxidation of propene under UV irradiation, especially after the calcination of the samples. During calcination, there is a change in the Ti(IV) coordination and an increase in the content of SiOTi moieties in comparison with the uncalcined materials, which seems to be responsible for the enhanced photocatalytic activity of hybrid titania-silica materials as compared to both uncalcined samples and the control TiO2 .

  16. Characterisation of interfaces in nanocrystalline palladium

    Indian Academy of Sciences (India)

    R Divakar; V S Raghunathan

    2003-02-01

    Structures of grain boundaries and triple line junctions in nanocrystalline materials are of interest owing to large fractions of atoms in nanocrystalline materials being at these interfacial positions. Grain boundary and triple line junction structures in nanocrystalline palladium have been studied using high-resolution transmission electron microscopy (HRTEM). The main microstructural features observed include the varying atomic structures of grain boundaries and the presence of disordered regions at triple line junctions. Also, there is variation in lattice parameters in different nanocrystalline grains. Geometric phase analysis is used to quantify atomic displacements within nanocrystalline grains. Displacement fields thus detected indicate links to the interface structures.

  17. Gelatin-templated mesoporous titania for photocatalytic air treatment and application in metal chalcogenide nanoparticle-sensitized solar cells.

    Science.gov (United States)

    Stroyuk, Oleksandr L; Rayevska, Oleksandra Ye; Shvalagin, Vitaly V; Kuchmiy, Stepan Ya; Bavykin, Dmitry V; Streltsov, Eugene A; Poznyak, Sergey K

    2013-04-01

    Mesoporous titania as powders and thin films on ITO were prepared using gelatin as an available and non-expensive pore-forming agent. The mesoporous TiO2 manifested a much higher photocatalytic activity in the gas-phase air oxidation of ethanol and acetaldehyde than the commercial nanocrystalline TiO2 P25 (Degussa Corp.). The mesoporous ITO/TiO2 films exhibited 12-14% efficiency of photocurrent generation in aqueous Na2S electrolyte when illuminated by UV light. Deposition of CdS and PbS nanoparticles onto the surface of ITO/TiO2 further increases the photocurrent yields and expands the light sensitivity range of the films to 500-520 nm (CdS) and to 650-700 nm (PbS).

  18. Nanocrystalline magnetic alloys and ceramics

    Indian Academy of Sciences (India)

    M Pal; D Chakravorty

    2003-02-01

    Magnetic properties of materials in their nanocrystalline state have assumed significance in recent years because of their potential applications. A number of techniques have been used to prepare nanocrystalline magnetic phases. Melt spinning, high energy ball milling, sputtering, glassceramization and molecular beam epitaxy are some of the physical methods used so far. Among the chemical methods, sol-gel and co-precipitation routes have been found to be convenient. Ultrafine particles of both ferro- and ferrimagnetic systems show superparamagnetic behaviour at room temperature. Coercivity $(H_c)$ and maximum energy product $(BH)_{\\text{max}}$ of the magnetic particles can be changed by controlling their sizes. The present paper reviews all these aspects in the case of nanocrystalline magnetic systems — both metallic and ceramics.

  19. Electrochemical biosensing based on polypyrrole/titania nanotube hybrid.

    Science.gov (United States)

    Xie, Yibing; Zhao, Ye

    2013-12-01

    The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. © 2013 Elsevier B.V. All rights reserved.

  20. Preparation of nitrogen-doped titania and its photocatalytic activity

    Institute of Scientific and Technical Information of China (English)

    QIN Haoli; GU Guobang; LIU Song

    2007-01-01

    Yellowish nitrogen-doped titania was produced through sol-gel method in mild condition, with the elemental nitrogen derived from aqua ammonia. The titania catalysts were characterized using XRD, BET, TEM, XPS, and UV-Vis diffuse reflectance spectrophotometer, and their photocatalytic activities were evaluated under UV and visible light, respectively. The XRD results showed that all titania catalysts were anatase. More significantly, the crystallite size of nitrogen-doped titania increased with an increase in N/Ti proportion, and the doping of nitrogen could extend the absorption shoulder into the visible-light region, thus it possessed a higher visible-light activity illustrated by decolorization of methyl orange (65.3%) under the irradiation of visible light, whereas pure titania showed little of such kind of visible light activity.The UV-light activity of nitrogen-doped titania catalysts was worse than that of pure titania and Degussa P25. In the range of N/Ti proportion of 4-10 mol%, the activity of nitrogen-doped titania weakened appreciably in the visible-light region as the N/Ti proportion increased, whereas a reverse relationship existed under the irradiation of UV light.

  1. Ultrahigh temperature-sensitive silicon MZI with titania cladding

    Directory of Open Access Journals (Sweden)

    Jong-Moo eLee

    2015-05-01

    Full Text Available We present a possibility of intensifying temperature sensitivity of a silicon Mach-Zehnder interferometer (MZI by using a highly negative thermo-optic property of titania (TiO2. Temperature sensitivity of an asymmetric silicon MZI with a titania cladding is experimentally measured from +18pm/C to -340 pm/C depending on design parameters of MZI.

  2. One step synthesis and characterization of copper doped sulfated titania and its enhanced photocatalytic activity in visible light by degradation of methyl orange

    Institute of Scientific and Technical Information of China (English)

    Radha Devi Chekuri; Siva Rao Tirukkovalluri

    2016-01-01

    This paper reports on the synthesis of copper doped sulfated titania nano-crystalline powders with varying (2.0%–10.0%, by mass) by single step sol gel method. The synthesized photo catalyst has been characterized by employing various techniques like X-ray Diffraction (XRD), Ultraviolet–Visible Diffuse Reflection Spectroscopy (UV–Vis DRS), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), Fourier Transform Infrared Spectroscopic Studies (FT-IR), and Transmission Electron Microscopy (TEM). From the XRD and TEM results, al the samples were reported in anatase phase with reduction in particle size in the range of 7 to 12 nm. SEM indicated the change in morphology of the particles. The presence of copper in titania lattice was evidenced by XPS. From UV–Vis DRS and FT-IR studies indicated that prominent absorption shift is observed towards visible region (red shift), the entry of Cu2+into TiO2 lattice as a substitution-al dopant and SO42− ions were covalently bonded with Ti4+ on the surface of the copper doped titania respectively. The photocatalytic activity studies were investigated by considering methyl orange (MO) as dye pol utant in the presence of the visible light. The effect of various parameters like effect of dosage of the catalyst, dopant concentration, pH of the solution, and concentration of the dye was studied in detail.

  3. Nanostructured carbon-crystalline titania composites from microphase separation of poly(ethylene oxide-b-acrylonitrile) and titania sols.

    Science.gov (United States)

    Stefik, Morgan; Lee, Jinwoo; Wiesner, Ulrich

    2009-05-14

    A simple "one-pot" method utilizing a graphitic carbon source containing poly(ethylene oxide-b-acrylonitrile) diblock copolymer as a structure directing agent was used to synthesize carbon-crystalline titania composites as well as crystalline mesoporous titania materials after oxidative carbon removal.

  4. Structural Formation and Photocatalytic Activity of Magnetron Sputtered Titania and Doped-Titania Coatings

    Directory of Open Access Journals (Sweden)

    Peter J. Kelly

    2014-10-01

    Full Text Available Titania and doped-titania coatings can be deposited by a wide range of techniques; this paper will concentrate on magnetron sputtering techniques, including “conventional” reactive co-sputtering from multiple metal targets and the recently introduced high power impulse magnetron sputtering (HiPIMS. The latter has been shown to deliver a relatively low thermal flux to the substrate, whilst still allowing the direct deposition of crystalline titania coatings and, therefore, offers the potential to deposit photocatalytically active titania coatings directly onto thermally sensitive substrates. The deposition of coatings via these techniques will be discussed, as will the characterisation of the coatings by XRD, SEM, EDX, optical spectroscopy, etc. The assessment of photocatalytic activity and photoactivity through the decomposition of an organic dye (methylene blue, the inactivation of E. coli microorganisms and the measurement of water contact angles will be described. The impact of different deposition technologies, doping and co-doping strategies on coating structure and activity will be also considered.

  5. Characterisation Studies of the Structure and Properties of As-Deposited and Annealed Pulsed Magnetron Sputtered Titania Coatings

    Directory of Open Access Journals (Sweden)

    John A. Ridealgh

    2013-09-01

    Full Text Available Titanium dioxide thin films are durable, chemically stable, have a high refractive index and good electro/photochemical proprieties. Consequently, they are widely used as anti-reflective layers in optical devices and large area glazing products, dielectric layers in microelectronic devices and photo catalytic layers in self-cleaning surfaces. Titania coatings may have amorphous or crystalline structures, where three crystalline phases of TiO2 can be obtained: anatase, rutile and brookite, although the latter is rarely found. It is known, however, that the structure of TiO2 coatings is sensitive to deposition conditions and can also be modified by post-deposition heat treatments. In this study, titania coatings have been deposited onto soda-lime glass substrates by reactive sputtering from a metallic target. The magnetron was driven in mid-frequency pulsed DC mode. The as-deposited coatings were analysed by micro Raman spectroscopy, X-ray diffraction (XRD, atomic force microscopy (AFM and scanning electron microscopy (SEM. Selected coatings were annealed at temperatures in the range 200–700 °C and re-analysed. Whilst there was weak evidence of a nanocrystallinity in the as-deposited films, it was observed that these largely amorphous low temperature structures converted into strongly crystalline structures at annealing temperatures above 400 °C.

  6. Nano-Titania Photocatalyst Loaded on W-MCM-41 Support and Its Highly Efficient Degradation of Methylene Blue

    Science.gov (United States)

    Shankar, H.; Saravanan, R.; Narayanan, V.; Stephen, A.

    2011-07-01

    Most of the azo dyes produced in textile, printing, paper manufacturing, pulp processing and pharmaceutical industries contain different organic contaminants. These dyes can enter the body through ingestion and the high content in living systems can prove to be carcinogenic. Therefore photocatalytic degradation of such toxic organic compounds in water, in the presence of semiconductor powders has received much attention over the last two decades. Nanocrystalline titanium dioxide, TiO2, is a well studied and commonly used material for photocatalytic applications. However, the control of particle size, monodispersity, large catalytic surface for sufficient adsorption of organic pollutants, recovery and recycle of TiO2 nanoparticles are challenging tasks. Hence in the present study, titania was introduced into the nanopores (2-10 nm size) of MCM-41 to produce stable nanoparticles of uniform size and shape. Further, in order to lengthen the life time of the excited electrons/holes during photoreaction, tungsten atoms were incorporated in to the MCM-41 silica matrix in addition to titania loading.

  7. Laser Compression of Nanocrystalline Metals

    Science.gov (United States)

    Meyers, M. A.; Jarmakani, H. N.; Bringa, E. M.; Earhart, P.; Remington, B. A.; Vo, N. Q.; Wang, Y. M.

    2009-12-01

    Shock compression in nanocrystalline nickel is simulated over a range of pressures (10-80 GPa) and compared with experimental results. Laser compression carried out at Omega and Janus yields new information on the deformation mechanisms of nanocrystalline Ni. Although conventional deformation does not produce hardening, the extreme regime imparted by laser compression generates an increase in hardness, attributed to the residual dislocations observed in the structure by TEM. An analytical model is applied to predict the critical pressure for the onset of twinning in nanocrystalline nickel. The slip-twinning transition pressure is shifted from 20 GPa, for polycrystalline Ni, to 80 GPa, for Ni with g. s. of 10 nm. Contributions to the net strain from the different mechanisms of plastic deformation (partials, perfect dislocations, twinning, and grain boundary shear) were quantified in the nanocrystalline samples through MD calculations. The effect of release, a phenomenon often neglected in MD simulations, on dislocation behavior was established. A large fraction of the dislocations generated at the front are annihilated.

  8. Superb nanocrystalline alloys for plating

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ With high rigidity and antiwear performance,nanocrystalline metals and their alloys can find wide applications in surface protection.However, the existence of grain boundaries often leads to erosive micro-batteries which accelerate the process of corrosion.Therefore, it has already become a key issue for surface engineering researchers to find nano materials with higher lubricating, anticorrosion and antiwear capacities.

  9. Nanocrystalline materials: recent advances in crystallographic characterization techniques

    Directory of Open Access Journals (Sweden)

    Emilie Ringe

    2014-11-01

    Full Text Available Most properties of nanocrystalline materials are shape-dependent, providing their exquisite tunability in optical, mechanical, electronic and catalytic properties. An example of the former is localized surface plasmon resonance (LSPR, the coherent oscillation of conduction electrons in metals that can be excited by the electric field of light; this resonance frequency is highly dependent on both the size and shape of a nanocrystal. An example of the latter is the marked difference in catalytic activity observed for different Pd nanoparticles. Such examples highlight the importance of particle shape in nanocrystalline materials and their practical applications. However, one may ask `how are nanoshapes created?', `how does the shape relate to the atomic packing and crystallography of the material?', `how can we control and characterize the external shape and crystal structure of such small nanocrystals?'. This feature article aims to give the reader an overview of important techniques, concepts and recent advances related to these questions. Nucleation, growth and how seed crystallography influences the final synthesis product are discussed, followed by shape prediction models based on seed crystallography and thermodynamic or kinetic parameters. The crystallographic implications of epitaxy and orientation in multilayered, core-shell nanoparticles are overviewed, and, finally, the development and implications of novel, spatially resolved analysis tools are discussed.

  10. Nanocrystalline materials: recent advances in crystallographic characterization techniques.

    Science.gov (United States)

    Ringe, Emilie

    2014-11-01

    Most properties of nanocrystalline materials are shape-dependent, providing their exquisite tunability in optical, mechanical, electronic and catalytic properties. An example of the former is localized surface plasmon resonance (LSPR), the coherent oscillation of conduction electrons in metals that can be excited by the electric field of light; this resonance frequency is highly dependent on both the size and shape of a nanocrystal. An example of the latter is the marked difference in catalytic activity observed for different Pd nanoparticles. Such examples highlight the importance of particle shape in nanocrystalline materials and their practical applications. However, one may ask 'how are nanoshapes created?', 'how does the shape relate to the atomic packing and crystallography of the material?', 'how can we control and characterize the external shape and crystal structure of such small nanocrystals?'. This feature article aims to give the reader an overview of important techniques, concepts and recent advances related to these questions. Nucleation, growth and how seed crystallography influences the final synthesis product are discussed, followed by shape prediction models based on seed crystallography and thermodynamic or kinetic parameters. The crystallographic implications of epitaxy and orientation in multilayered, core-shell nanoparticles are overviewed, and, finally, the development and implications of novel, spatially resolved analysis tools are discussed.

  11. Nanocrystalline materials: recent advances in crystallographic characterization techniques

    Science.gov (United States)

    Ringe, Emilie

    2014-01-01

    Most properties of nanocrystalline materials are shape-dependent, providing their exquisite tunability in optical, mechanical, electronic and catalytic properties. An example of the former is localized surface plasmon resonance (LSPR), the coherent oscillation of conduction electrons in metals that can be excited by the electric field of light; this resonance frequency is highly dependent on both the size and shape of a nanocrystal. An example of the latter is the marked difference in catalytic activity observed for different Pd nanoparticles. Such examples highlight the importance of particle shape in nanocrystalline materials and their practical applications. However, one may ask ‘how are nanoshapes created?’, ‘how does the shape relate to the atomic packing and crystallography of the material?’, ‘how can we control and characterize the external shape and crystal structure of such small nanocrystals?’. This feature article aims to give the reader an overview of important techniques, concepts and recent advances related to these questions. Nucleation, growth and how seed crystallography influences the final synthesis product are discussed, followed by shape prediction models based on seed crystallography and thermodynamic or kinetic parameters. The crystallographic implications of epitaxy and orientation in multilayered, core-shell nanoparticles are overviewed, and, finally, the development and implications of novel, spatially resolved analysis tools are discussed. PMID:25485133

  12. Hydrogen peroxide route to Sn-doped titania photocatalysts

    Directory of Open Access Journals (Sweden)

    Štengl Václav

    2012-10-01

    Full Text Available Abstract Background The work aims at improving photocatalytic activity of titania under Vis light irradiation using modification by Sn ions and an original, simple synthesis method. Tin-doped titania catalysts were prepared by thermal hydrolysis of aqueous solutions of titanium peroxo-complexes in the presence of SnCl4 or SnCl2 using an original, proprietary "one pot" synthesis not employing organic solvents, metallo-organic precursors, autoclave aging nor post-synthesis calcination. The products were characterized in details by powder diffraction, XPS, UV–vis, IR, and Raman spectroscopies, electron microscopy and surface area and porosity measurements Results The presence of tin in synthesis mixtures favors the formation of rutile and brookite at the expense of anatase, decreases the particle size of all formed titania polymorphs, and extends light absorption of titania to visible light region >400 nm by both red shift of the absorption edge and introduction of new chromophores. The photocatalytic activity of titania under UV irradiation and >400 nm light was tested by decomposition kinetics of Orange II dye in aqueous solution Conclusions Doping by Sn improves titania photoactivity under UV light and affords considerable photoactivity under >400 nm light due to increased specific surface area and a phase heterogeneity of the Sn-doped titania powders.

  13. Hydrogen peroxide route to Sn-doped titania photocatalysts

    Science.gov (United States)

    2012-01-01

    Background The work aims at improving photocatalytic activity of titania under Vis light irradiation using modification by Sn ions and an original, simple synthesis method. Tin-doped titania catalysts were prepared by thermal hydrolysis of aqueous solutions of titanium peroxo-complexes in the presence of SnCl4 or SnCl2 using an original, proprietary "one pot" synthesis not employing organic solvents, metallo-organic precursors, autoclave aging nor post-synthesis calcination. The products were characterized in details by powder diffraction, XPS, UV–vis, IR, and Raman spectroscopies, electron microscopy and surface area and porosity measurements Results The presence of tin in synthesis mixtures favors the formation of rutile and brookite at the expense of anatase, decreases the particle size of all formed titania polymorphs, and extends light absorption of titania to visible light region >400 nm by both red shift of the absorption edge and introduction of new chromophores. The photocatalytic activity of titania under UV irradiation and >400 nm light was tested by decomposition kinetics of Orange II dye in aqueous solution Conclusions Doping by Sn improves titania photoactivity under UV light and affords considerable photoactivity under >400 nm light due to increased specific surface area and a phase heterogeneity of the Sn-doped titania powders. PMID:23035821

  14. The mechanism of action of titania catalysts in sulfur recovery

    Energy Technology Data Exchange (ETDEWEB)

    Clark, P.D.; Dowling, N.I.; Huang, M.

    2010-01-15

    The mechanism recovering sulfur from hydrocarbons using titania catalysts in a commercial titanium oxide (TiO{sub 2}) Claus process was investigated. Titania (Ti{sup 3+}) was obtained by hydrogen sulfide (H{sub 2}S) treatment at 320 degrees C for 1 hour. The presence of Ti{sup 3+} increases carbon disulphide (CS{sub 2}) hydrolysis as well as the CS{sub 2} conversion activities at the first converter condition. The catalytic behaviour of titania in the Claus process was described. The high CS{sub 2} activity of titania at first and second converted conditions was described along with its ability to promote conversion via either hydrolysis or reaction with sulphur dioxide (SO{sub 2}). The surface sulfate on titania is more active at first converter condition, but the slow turnover of sulfate back to thiosulfates at low temperature inhibits the Claus reaction and the carbon disulphide conversion at the third converter condition. Comparing alumina and titania for carbon disulphide conversion, titania gives a better conversion over time, although during the first 6 hours of the process alumina appears to provide the better conversion. 12 figs.

  15. Hydrogen peroxide route to Sn-doped titania photocatalysts.

    Science.gov (United States)

    Stengl, Václav; Grygar, Tomáš Matys; Henych, Jiří; Kormunda, Martin

    2012-10-05

    The work aims at improving photocatalytic activity of titania under Vis light irradiation using modification by Sn ions and an original, simple synthesis method. Tin-doped titania catalysts were prepared by thermal hydrolysis of aqueous solutions of titanium peroxo-complexes in the presence of SnCl4 or SnCl2 using an original, proprietary "one pot" synthesis not employing organic solvents, metallo-organic precursors, autoclave aging nor post-synthesis calcination. The products were characterized in details by powder diffraction, XPS, UV-vis, IR, and Raman spectroscopies, electron microscopy and surface area and porosity measurements The presence of tin in synthesis mixtures favors the formation of rutile and brookite at the expense of anatase, decreases the particle size of all formed titania polymorphs, and extends light absorption of titania to visible light region >400 nm by both red shift of the absorption edge and introduction of new chromophores. The photocatalytic activity of titania under UV irradiation and >400 nm light was tested by decomposition kinetics of Orange II dye in aqueous solution Doping by Sn improves titania photoactivity under UV light and affords considerable photoactivity under >400 nm light due to increased specific surface area and a phase heterogeneity of the Sn-doped titania powders.

  16. Titania coated hollow glass microspheres for environmental applications

    Science.gov (United States)

    Koopman, Mark C.

    The potential applicability of titania coated hollow glass microspheres (HGMs) to the photocatalytic degradation of microbiological and organic chemical water pollutants could have dramatic positive effects on improving the quality of industrial wastewaters that empty into rivers and streams, as well as potential use in economically improving the quality of drinking water. Heterogeneous photocatalysis using titania has been extensively studied since the 1990's because of its non-toxic nature, its high quantum yield of electrons and photo-holes, and its ability to use ambient solar radiation as a power source. Although titania embodies extraordinarily attractive properties for a range of environmental applications, a viable substrate or method of using the material effectively has not been recognized. HGMs are particularly attractive as a support for titania because of their low density and high surface area to volume ratio, but details of how they react to imposed loading, wear, and impact have not been addressed, nor have materials engineering analyses that could maximize their utility been made. In this study we have examined the microstructure, morphology and micro-compression properties of two types of titania coated hollow microspheres, a commercially produced HGM and cenospheres, a derivative of fly ash. Comparisons of uncoated and titania coated hollow microspheres showed improved failure loads and facture energies for the titania coated materials over the uncoated hollow microspheres. Also, the relationship between failure load and hollow microsphere diameter was characterized and the function employed to explain part of the gain in average failure load for the HGMs. Microscopic examination of titania coated HGMs that were subjected to various turbulent conditions, as well as intentional fracture, indicated good interfacial integrity, which supports the viability of both types of HGMs for potential applications. The photocatalytic reactivity of the titania

  17. Hydrogenations without Hydrogen: Titania Photocatalyzed Reductions of Maleimides and Aldehydes

    Directory of Open Access Journals (Sweden)

    David W. Manley

    2014-09-01

    Full Text Available A mild procedure for the reduction of electron-deficient alkenes and carbonyl compounds is described. UVA irradiations of substituted maleimides with dispersions of titania (Aeroxide P25 in methanol/acetonitrile (1:9 solvent under dry anoxic conditions led to hydrogenation and production of the corresponding succinimides. Aromatic and heteroaromatic aldehydes were reduced to primary alcohols in similar titania photocatalyzed reactions. A mechanism is proposed which involves two proton-coupled electron transfers to the substrates at the titania surface.

  18. Synthesis and photocatalytic activity of mesoporous nanocrystalline Fe-doped titanium dioxide

    KAUST Repository

    Qamar, Mohd

    2014-07-01

    Synthesis of mesoporous nanocrystalline iron-doped titania following the sol-gel method is presented in this work. Samples with various molar ratios (0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 10 and 20%) of Fe to Ti were prepared. The particle size was found to be in the range of ∼12 nm while mesopores were approximately near to ∼5.5 nm. The effect of Fe as doping element on titania properties, such as crystallite size, surface area, pore size, pore volume and d-spacing was investigated. Moreover, distribution of Fe in TiO2 matrix was determined by elemental mapping whereas change in absorption properties was evaluated by diffuse reflectance spectroscopy. It was observed that as the Fe content was increased, a partial phase transformation from anatase to rutile and pseudorutile took place. Effect of ultraviolet, ultraviolet-visible and visible radiations on the photocatalytic activity of these catalysts was studied by removal of Methyl Orange as model pollutant. As results, it was found that the photocatalytic activity of such catalysts depends strongly on Fe amount and type of radiation. © 2013 Elsevier B.V.

  19. Deformation Twinning During Nanoindentation of Nanocrystalline Ta

    OpenAIRE

    Wang, Y. M.; Hodge, A. M.; Biener, J.; Hamza, A.V.; Barnes, D E; Liu, Kai; Nieh, T. G.

    2005-01-01

    The deformation mechanism of body-centered cubic (bcc) nanocrystalline tantalum with grain sizes of 10–30 nm is investigated by nanoindentation, scanning electron microscopy and high-resolution transmission electron microscopy. In a deviation from molecular dynamics simulations and existing experimental observations on other bcc nanocrystalline metals, the plastic deformation of nanocrystalline Ta during nanoindentation is controlled by deformation twinning. The observation of multiple twin i...

  20. Thermal stability of nanocrystalline W-Ti diffusion barrier thin films

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Nanocrystalline W-Ti diffusion barrier thin films with different phase structures and Cu/barrier/Si multilayer structures were deposited on p-type Si(100) substrates by DC magnetron sputtering.These films were annealed at different temperatures for 1 h.The diffusion barrier properties and thermal stability were studied using four-probe tester(FPP),XRD,AFM,XPS,FESEM,and HRTEM.The experimental results showed that the films were stable up to 700℃.When the annealing temperature was increased,the Cu and Ti atoms began to react and CuTi3 was formed.In addition,the high resistance Cu3Si was formed due to inter-diffusion between the Si and Cu atoms which made the surface rougher and caused the sheet resistance to increase abruptly.At the same time,failure mechanism of the nanocrystalline W-Ti diffusion barrier thin films during annealing process was also discussed.

  1. Altering strength and plastic deformation behavior via alloying and laminated structure in nanocrystalline metals

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, F., E-mail: wangfei@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Huang, P., E-mail: huangping@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Lu, T.J. [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); MOE Key Laboratory for Multifunctional Materials and Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Xu, K.W. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China)

    2015-07-29

    Nanoindentation and electron microscope techniques have been performed on sputtering deposited monolayered nanocrystalline CuNb and multilayered CuNb/Cu thin films. Microstructural features, hardness and surface morphologies of residual indentation have been evaluated to identify the effects of alloying and laminated structure on strength and plastic deformation behavior of nanocrystalline metals. By altering the content of Nb in CuNb alloy and adding crystalline Cu layers into CuNb alloy, the volume fraction of amorphous phase in CuNb alloy and interface structures changed dramatically, resulting in various trends that are related to hardness, indentation induced pileup and shear banding deformation. Based on the experimental results, the dominant deformation mechanisms of the CuNb and CuNb/Cu thin films with various Nb contents were proposed and extended to be discussed.

  2. Photocatalytic activity of titania coatings synthesised by a combined laser/sol–gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Adraider, Y. [School of Science and Engineering, Teesside University, Middlesbrough TS1 3BA (United Kingdom); Pang, Y.X., E-mail: F6098038@tees.ac.uk [School of Science and Engineering, Teesside University, Middlesbrough TS1 3BA (United Kingdom); Nabhani, F.; Hodgson, S.N. [School of Science and Engineering, Teesside University, Middlesbrough TS1 3BA (United Kingdom); Sharp, M.C.; Al-Waidh, A. [General Engineering Research Institute, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom)

    2014-06-01

    Highlights: • Sol–gel method was used to prepare titania coatings. • Titania thin films were coated on substrate surface by dip coating. • Fibre laser was employed to irradiate the titania coated surfaces. • Photocatalytic efficiency of titania coatings was significantly improved after laser processing. - Abstract: Titania coatings were prepared using sol–gel method and then applied on the substrate surface by dip coating. Fibre laser (λ = 1064 nm) in continuous wave mode was used to irradiate the titania coated surfaces at different specific energies. The ATR-FTIR, XRD, SEM, EDS and contact angle measurement were employed to analyse surface morphology, phase composition and crystalline structure of laser-irradiated titania coatings, whilst the photocatalytic activity was evaluated by measuring the decomposition of methylene blue (MB) after exposure to the visible light for various illumination times. Results showed that the laser-irradiated titania coatings demonstrate significant different composition and microstructure in comparison with the as-coated from the same sol–gel titania. Photocatalytic efficiency of titania coatings was significantly improved after laser processing. The photocatalytic activity of laser-irradiated titania coatings was higher than that of the as-coated titania. The titania coating processed at laser specific energy of 6.5 J/mm{sup 2} exhibited the highest photocatalytic activity among all titania samples.

  3. Nanocrystalline diamond films for biomedical applications

    DEFF Research Database (Denmark)

    Pennisi, Cristian Pablo; Alcaide, Maria

    2014-01-01

    performance of nanocrystalline diamond films is reviewed from an application-specific perspective, covering topics such as enhancement of cellular adhesion, anti-fouling coatings, non-thrombogenic surfaces, micropatterning of cells and proteins, and immobilization of biomolecules for bioassays. In order......Nanocrystalline diamond films, which comprise the so called nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD), represent a class of biomaterials possessing outstanding mechanical, tribological, and electrical properties, which include high surface smoothness, high corrosion...... resistance, chemical inertness, superior electrochemical behavior, biocompatibility, and nontoxicity. These properties have positioned the nanocrystalline diamond films as an attractive class of materials for a range of therapeutic and diagnostic applications in the biomedical field. Consequently...

  4. The application of electrospun titania nanofibers in dye-sensitized solar cells.

    Science.gov (United States)

    Krysova, Hana; Zukal, Arnost; Trckova-Barakova, Jana; Chandiran, Aravind Kumar; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Kavan, Ladislav

    2013-01-01

    Titania nanofibers were fabricated using the industrial Nanospider(TM) technology. The preparative protocol was optimized by screening various precursor materials to get pure anatase nanofibers. Composite films were prepared by mixing a commercial paste of nanocrystalline anatase particles with the electrospun nanofibers, which were shortened by milling. The composite films were sensitized by Ru-bipyridine dye (coded C106) and the solar conversion efficiency was tested in a dye-sensitized solar cell filled with iodide-based electrolyte solution (coded Z960). The solar conversion efficiency of a solar cell with the optimized composite electrode (η = 7.53% at AM 1.5 irradiation) outperforms that of a solar cell with pure nanoparticle film (η = 5.44%). Still larger improvement was found for lower light intensities. At 10% sun illumination, the best composite electrode showed η = 7.04%, referenced to that of pure nanoparticle film (η = 4.69%). There are non-monotonic relations between the film's surface area, dye sorption capacity and solar performance of nanofiber-containing composite films, but the beneficial effect of the nanofiber morphology for enhancement of the solar efficiency has been demonstrated.

  5. Tensile behavior of nanocrystalline copper

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, P.G.; Weertman, J.R. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Eastman, J.A. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering]|[Argonne National Lab., IL (United States). Materials Science Div.

    1995-11-01

    High density nanocrystalline copper produced by inert gas condensation was tested in tension. Displacements were measured using foil strain gauges, which greatly improved the accuracy of the strain data. The Young`s modulus of nanocrystalline copper was found to be consistent with that of coarse-grained copper. Total elongations of {approx} 1% were observed in samples with grain sizes less than 50 nm, while a sample with a grain size of 110 nm exhibited more than 10% elongation, perhaps signifying a change to a dislocation-based deformation mechanism in the larger-grained material. In addition, tensile tests were performed as a function of strain rate, with a possible trend of decreased strength and increased elongation as the strain rate was decreased.

  6. Titania: a material-based approach to oil spill remediation?

    Directory of Open Access Journals (Sweden)

    Roger Narayan

    2010-09-01

    Full Text Available The anatase phase of titania is being considered for use in oil spill remediation due to its high photocatalytic efficiency and its activity under a wide range of environmental conditions.

  7. Design of hybrid titania nanocrystallites as supports for gold catalysts.

    Science.gov (United States)

    Mendez, Violaine; Caps, Valérie; Daniele, Stéphane

    2009-06-07

    Citrate-functionalized titania nanocrystallites are successfully synthesized from a heteroleptic titanium alkoxide precursor in a low temperature, hydrolytic process and used as gold catalyst supports for CO oxidation and aerobic stilbene epoxidation.

  8. Modulation of mixed-phase titania photoluminescence by oxygen adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Pallotti, D.; Orabona, E.; Amoruso, S.; Maddalena, P. [Dipartimento di Fisica, Universitá degli Studi di Napoli “Federico II,” Via Cintia, I-80126 Napoli (Italy); Institute for Superconductors, Oxides and Innovative Materials and Devices, CNR-SPIN, U.O.S. Napoli, Via Cintia, I-80126 Napoli (Italy); Lettieri, S., E-mail: stefano.lettieri@spin.cnr.it [Institute for Superconductors, Oxides and Innovative Materials and Devices, CNR-SPIN, U.O.S. Napoli, Via Cintia, I-80126 Napoli (Italy)

    2014-07-21

    We investigate the effect of oxygen (O{sub 2}) adsorption on photoluminescence properties of mixed-phase titania nanoparticle films deposited by femtosecond pulsed laser deposition, aiming to assess preliminary conclusions about the feasibility of opto-chemical sensing based on titania. We evidence that O{sub 2} produces opposite responses in rutile and anatase photoluminescence efficiency, highlighting interesting potentialities for future double-parametric optical sensing based on titania. The results evidence an important role of lattice oxygen atoms, suggesting that the standard Schottky barrier mechanism driving the response toward gas species in most used metal-oxide sensors (e.g., tin dioxide) is not the only active mechanism in titania.

  9. Intergranular fracture in nanocrystalline metals

    Science.gov (United States)

    Farkas, D.; van Swygenhoven, H.; Derlet, P. M.

    2002-08-01

    Crack propagation studies in nanocrystalline Ni samples with mean grain sizes ranging from 5 to 12 nm are reported using atomistic simulations. For all grain sizes pure intergranular fracture is observed. Intergranular fracture is shown to proceed by the coalescence of microvoids formed at the grain boundaries ahead of the crack. The energy released during propagation is higher than the Griffith value, indicating an additional grain-boundary accommodation mechanism.

  10. Synthesis, characterization and photocatalytic reactions of phosphated mesoporous titania

    Indian Academy of Sciences (India)

    Pallabi Goswami; Jatindra Nath Ganguli

    2012-10-01

    Mesoporous titania nanoparticles with a well-definedmesostructure was prepared by hydrothermal process, using nonionic triblock copolymer P123 as surfactant template, modified with phosphoric acid and followed by calcination at 600°C. The sol–gel titania was modified by in situ phosphorylation using phosphoric acid and thereby incorporating phosphorous directly into the framework of TiO2. The resulting materials were characterized by XRD, SEM, TEM, nitrogen adsorption, TGA and DRS. It was found that the structural and optical properties of titania samples are strongly influenced by their phosphate modification. In case of calcined samples a positive effect on the specific surface area for the in situ phosphated sample was found. Mesoporous structure of phosphated titania did not collapse even after calcination at 600°C. The enhanced photocatalytic activity of the synthesized phosphate nanomaterials were evaluated through a study of the decomposition of fluorescein under UV light excitation and compared with undoped titania nanomaterial as well as with commercial titania.

  11. Titanium complex formation of organic ligands in titania gels.

    Science.gov (United States)

    Nishikiori, Hiromasa; Todoroki, Kenta; Setiawan, Rudi Agus; Teshima, Katsuya; Fujii, Tsuneo; Satozono, Hiroshi

    2015-01-27

    Thin films of organic ligand-dispersing titania gels were prepared from titanium alkoxide sols containing ligand molecules by steam treatment without heating. The formation of the ligand-titanium complex and the photoinduced electron transfer process in the systems were investigated by photoelectrochemical measurements. The complex was formed between the 8-hydroxyquinoline (HQ) and titanium species, such as the titanium ion, on the titania nanoparticle surface through the oxygen and nitrogen atoms of the quinolate. A photocurrent was observed in the electrodes containing the complex due to the electron injection from the LUMO of the complex into the titania conduction band. A bidentate ligand, 2,3-dihydroxynaphthalene (DHN), formed the complex on the titania surface through dehydration between its two hydroxyl groups of DHN and two TiOH groups of the titania. The electron injection from the HOMO of DHN to the titania conduction band was observed during light irradiation. This direct electron injection was more effective than the two-step electron injection.

  12. Synthesis and characterization of titania nanorods from ilmenite for photocatalytic annihilation of E. coli.

    Science.gov (United States)

    Sethi, Diptipriya; Jada, Naresh; Kumar, Rohit; Ramasamy, Sakthivel; Pandey, Sony; Das, Trupti; Kalidoss, Jayasankar; Mukherjee, Partha Sarathi; Tiwari, Ashish

    2014-11-01

    Titania nanorod structures have been obtained by thermal plasma reduction of ilmenite (FeTiO₃) followed by chemical treatments. Inherently present iron in the titania nanorods acts as a dopant which results in shifting the absorption edge of titania from ultraviolet to visible region. X-ray diffraction (XRD) study confirms the existence of rutile phase of titania. X-ray Photoelectron Spectroscopy (XPS) reveals the presence of Ti(4+), O(2-), Fe(3+) and surface hydroxyl group. Transmission Electron Microscopy (TEM) confirms the formation of nanorod structure having width of 6 nm and length of 32 nm. Photocatalytic annihilation property of titania nanorods derived from ilmenite (titania-I), rutile titania obtained from titanium(IV) butoxide (titania-A) and Degussa P25 titania was studied under UV and UV-Visible irradiation conditions separately and compared. The time required for complete photocatalytic annihilation of Escherichiacoli cells are 10, 15 and 45 min under UV irradiation whereas it has taken 15, 10-15, 30 min under UV-Visible irradiation for titania-A, Degussa P25 titania and titania-I respectively. It is observed that titania-I shows significantly stronger antibacterial property under UV-Visible irradiation compared to UV alone.

  13. STUDI PREPARASI DAN KARAKTERISASI SEL SURYA BERBASIS TITANIA MELALUI PENYISIPAN LOGAM TEMBAGA (CU DENGAN BERBAGAI VARIASI MASSA PADA LAPISAN AKTIF TITANIA

    Directory of Open Access Journals (Sweden)

    Rita Prasetyowati

    2017-05-01

                This study aims to determine the effect of insertion of copper (Cu with a variety of mass to structure morphology and composition of surface layer of titania, absorbance of titania, resistance of titania and solar cell performance based on titania.. Solar cell performance is characterized from voltage of solar cell.                 Preparation of titania-copper layer (TiO2-Cu to form a paste was made using a sol-gel method. Pasta titania-copper deposited on a transparent electrode (Indium Tin Oxide with a doctor blade method. There were five variations of Cu mass pasted on layers of titania, namely 0,050 grams (Sample 1; 0,075 grams (sample 2; 0,100 grams (3 samples; 0.0125 (sample 4 and 0.0150 (sample 5. Each variation of the mass of Cu is inserted in one gram of TiO2. SEM and EDS characterization performed on layers of titania-copper to know the structure morphology and composition of the titania-copper. Layer absorbance was characterized using UV-Visible spectrometer. Resistance of titania was measured using a Wheatstone bridge. The performance of solar cells measured by measuring the voltage of the solar cell.                  Keywords: titania, copper, surface morphology, absorbance, resistance, solar cells

  14. Structure and thermal stability of nanocrystalline materials

    Indian Academy of Sciences (India)

    B S Murty; M K Datta; S K Pabi

    2003-02-01

    Nanocrystalline materials, which are expected to play a key role in the next generation of human civilization, are assembled with nanometre-sized “building blocks” consisting of the crystalline and large volume fractions of intercrystalline components. In order to predict the unique properties of nanocrystalline materials, which are a combination of the properties of the crystalline and intercrystalline regions, it is essential to understand precisely how the structures of crystalline and intercrystalline regions vary with decrease in crystallite size. In addition, study of the thermal stability of nanocrystalline materials against significant grain growth is both scientific and technological interest. A sharp increase in grain size (to micron levels) during consolidation of nanocrystalline powders to obtain fully dense materials may consequently result in the loss of some unique properties of nanocrystalline materials. Therefore, extensive interest has been generated in exploring the size effects on the structure of crystalline and intercrystalline region of nanocrystalline materials, and the thermal stability of nanocrystalline materials against significant grain growth. The present article is aimed at understanding the structure and stability of nanocrystalline materials.

  15. Pattern formation in nanoporous titania templates.

    Science.gov (United States)

    Richter, C; Wu, Z; Menon, L

    2007-02-01

    We have carried out a systematic investigation into the formation of nanoscaled patterns in titania (TiO2) templates under dc anodization of Ti in HF acid. At lower acid concentrations (around 0.5 wt% HF) either pores or tubes form at the surface of anodized titanium foil. The pores or nanotubes are separated from the bottom Ti layer by a thin barrier layer of TiO2. The critical voltage where the transition from pores to tubes occurs has been determined. It is observed that the transition voltage shift towards higher voltages as acid concentration is increased, with pore formation disappearing altogether at high acid concentrations. We have also carried out a systematic investigation into the dependence of pore and tube parameters on the applied dc anodization voltage. Our results indicate that the barrier layer thickness, pore and tube length increase as a function of applied voltage.

  16. Preparation and corrosion behavior evaluation of amalgam/titania nano composite

    Directory of Open Access Journals (Sweden)

    Neda Bahremandi Tolou

    2011-01-01

    Conclusion: By adding nano particles of titania and preparing amalgam/titania nano composite as a dental amalgam, corrosion behavior and mercury release during the 2 st h after preparation could be improved.

  17. Interfacial effects in multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Barbee, T.W. Jr. [Lawrence Livermore National Lab., CA (United States). Chemistry and Materials Science Dept.

    1998-12-31

    Interfacial structure and the atomic interactions between atoms at interfaces in multilayers or nano-laminates have significant impact on the physical properties of these materials. A technique for the experimental evaluation of interfacial structure and interfacial structure effects is presented and compared to experiment. In this paper the impact of interfacial structure on the performance of x-ray, soft x-ray and extreme ultra-violet multilayer optic structures is emphasized. The paper is concluded with summary of these results and an assessment of their implications relative to multilayer development and the study of buried interfaces in solids in general.

  18. Controlled growth of silica-titania hybrid functional nanoparticles through a multistep microfluidic approach.

    Science.gov (United States)

    Shiba, K; Sugiyama, T; Takei, T; Yoshikawa, G

    2015-11-11

    Silica/titania-based functional nanoparticles were prepared through controlled nucleation of titania and subsequent encapsulation by silica through a multistep microfluidic approach, which was successfully applied to obtaining aminopropyl-functionalized silica/titania nanoparticles for a highly sensitive humidity sensor.

  19. Bulk nano-crystalline alloys

    OpenAIRE

    T.-S. Chin; Lin, C. Y.; Lee, M.C.; R.T. Huang; S. M. Huang

    2009-01-01

    Bulk metallic glasses (BMGs) Fe–B–Y–Nb–Cu, 2 mm in diameter, were successfully annealed to become bulk nano-crystalline alloys (BNCAs) with α-Fe crystallite 11–13 nm in size. A ‘crystallization-and-stop’ model was proposed to explain this behavior. Following this model, alloy-design criteria were elucidated and confirmed successful on another Fe-based BMG Fe–B–Si–Nb–Cu, 1 mm in diameter, with crystallite sizes 10–40 nm. It was concluded that BNCAs can be designed in general by the proposed cr...

  20. Increased fibroblast functionality on CNN2-loaded titania nanotubes.

    Science.gov (United States)

    Wei, Hongbo; Wu, Shuyi; Feng, Zhihong; Zhou, Wei; Dong, Yan; Wu, Guofeng; Bai, Shizhu; Zhao, Yimin

    2012-01-01

    Infection and epithelial downgrowth are major problems associated with maxillofacial percutaneous implants. These complications are mainly due to the improper closure of the implant-skin interface. Therefore, designing a percutaneous implant that better promotes the formation of a stable soft tissue biologic seal around percutaneous sites is highly desirable. Additionally, the fibroblast has been proven to play an important role in the formation of biologic seals. In this study, titania nanotubes were filled with 11.2 kDa C-terminal CCN2 (connective tissue growth factor) fragment, which could exert full CCN2 activity to increase the biological functionality of fibroblasts. This drug delivery system was fabricated on a titanium implant surface. CCN2 was loaded into anodized titania nanotubes using a simplified lyophilization method and the loading efficiency was approximately 80%. Then, the release kinetics of CCN2 from these nanotubes was investigated. Furthermore, the influence of CCN2-loaded titania nanotubes on fibroblast functionality was examined. The results revealed increased fibroblast adhesion at 0.25, 0.5, 1, 2, 4, and 24 hours, increased fibroblast viability over the course of 5 days, as well as enhanced actin cytoskeleton organization on CCN2-loaded titania nanotubes surfaces compared to uncoated, unmodified counterparts. Therefore, the results from this in vitro study demonstrate that CCN2-loaded titania nanotubes have the ability to increase fibroblast functionality and should be further studied as a method of promoting the formation of a stable soft tissue biologic seal around percutaneous sites.

  1. Titania based nanocomposites as a photocatalyst: A review

    Directory of Open Access Journals (Sweden)

    Farha Modi

    2016-08-01

    Full Text Available Titanium dioxide or Titania is a semiconductor compound having remarkable dielectric, electronic and physico-chemical surface properties. It has excellent photocatalytic efficiency in presence of UV light. The curious grey matter of scientists has forced them to focus their attention to make Titania capable of utilizing the whole visible spectrum of light also. The hurdle that they faced was larger band gap of 3 eV and more, for this, efforts were directed towards adding other materials to Titania. The present article reviews the recent advances in the synthesis of different Titanium-based nanocomposite materials and their photocatalytic efficiency so as to apply them for several applications such as removal of dyes, other water pollutants, microbes and metals. A brief explanation of the photocatalytic process and the structural properties of TiO2 are also touched upon. Various past and recent approaches made in these directions of utilizing Titania based nanocomposites for photocatalytic activities are reviewed. It is suggested that there is a need to establish the kinetics of photo-corrosion and thermodynamic part of the photo-corrosion of various composites developed by different group across the globe, so that Titania based nanocomposites could be commercially utilized.

  2. Study on Synthesis and Photocatalytic Activity of Porous Titania Nanotubes

    Directory of Open Access Journals (Sweden)

    Huang Liu

    2016-01-01

    Full Text Available Using the common natural cellulose substance (filter paper and triblock copolymer (Pluronic P123 micelles as dual templates, porous titania nanotubes with enhanced photocatalytic activity have been successfully synthesized through sol-gel methods. Firstly, P123 micelles were adsorbed onto the surfaces of cellulose nanofibers of filter paper, followed by hydrolysis and condensation of tetrabutyl titanate around these micelles to form titania layer. After calcination to remove the organic templates, hierarchical titania nanotubes with pores in the walls were obtained. The sample was characterized by X-ray diffraction pattern (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, nitrogen adsorption/desorption, Fourier Transform Infrared Spectroscopy (FT-IR, Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS, and X-ray photoelectron spectroscopy (XPS. As compared with commercial P25 catalyst, the porous titania nanotubes prepared by this method displayed significantly enhanced photocatalytic activity for degrading methyl orange under UV irradiation. Within 10 minutes, the porous titania nanotubes are able to degrade over 70% of the original MO, while the value for the commercial Degussa P25 is only about 33%.

  3. Nanocrystalline Fe-Pt alloys. Phase transformations, structure and magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Lyubina, J.V.

    2006-12-21

    This work has been devoted to the study of phase transformations involving chemical ordering and magnetic properties evolution in bulk Fe-Pt alloys composed of nanometersized grains. Nanocrystalline Fe{sub 100-x}Pt{sub x} (x=40-60) alloys have been prepared by mechanical ball milling of elemental Fe and Pt powders at liquid nitrogen temperature. The as-milled Fe-Pt alloys consist of {proportional_to} 100 {mu}m sized particles constituted by randomly oriented grains having an average size in the range of 10-40 nm. Depending on the milling time, three major microstructure types have been obtained: samples with a multilayer-type structure of Fe and Pt with a thickness of 20-300 nm and a very thin (several nanometers) A1 layer at their interfaces (2 h milled), an intermediate structure, consisting of finer lamellae of Fe and Pt (below approximately 100 nm) with the A1 layer thickness reaching several tens of nanometers (4 h milled) and alloys containing a homogeneous A1 phase (7 h milled). Subsequent heat treatment at elevated temperatures is required for the formation of the L1{sub 0} FePt phase. The ordering develops via so-called combined solid state reactions. It is accompanied by grain growth and thermally assisted removal of defects introduced by milling and proceeds rapidly at moderate temperatures by nucleation and growth of the ordered phases with a high degree of the long-range order. In a two-particle interaction model elaborated in the present work, the existence of hysteresis in recoil loops has been shown to arise from insufficient coupling between the low- and the high-anisotropy particles. The model reveals the main features of magnetisation reversal processes observed experimentally in exchange-coupled systems. Neutron diffraction has been used for the investigation of the magnetic structure of ordered and partially ordered nanocrystalline Fe-Pt alloys. (orig.)

  4. Preparation and characterization of perfluorosulfonic resin/titania hybrid transparent films

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Preparation and characterization of perfluorosulfonic resin/titania organic-inorganic hybrid films were presented. The transparent hybrid films were prepared by hydrothermal treatment at low temperature of a mixed solution of tetrabutyl titanate and perfluorosulfonic resin with the help of acetylacetone. The characterization was carried out by SEM,XRD,FT-IR,UV-Vis and TGA. The results showed that the perfluorosulfonic resin/titania hybrid transparent films were composed of titania particles dispersed in the perfluorosulfonic resin matrix very well and the titania was of anatase phase. Its diameter de-creased with increasing weight ratio of titania to perfluorosulfonic resin.

  5. Effect of photoanode surface coverage by a sensitizer on the photovoltaic performance of titania based CdS quantum dot sensitized solar cells.

    Science.gov (United States)

    Prasad, Rajendra M B; Pathan, Habib M

    2016-04-08

    In spite of the promising design and architecture, quantum dot sensitized solar cells (QDSSCs) have a long way to go before they attain the actual projected photoconversion efficiencies. Such an inferior performance displayed by QDSSCs is primarily because of many unwanted recombination losses of charge carriers at various interfaces of the cell. Electron recombination due to back electron transfer at the photoanode/electrolyte interface is an important one that needs to be addressed, to improve the efficiency of these third generation nanostructured solar cells. The present work highlights the importance of conformal coverage of CdS quantum dots (QDs) on the surface of the nanocrystalline titania photoanode in arresting such recombinations, leading to improvement in the performance of the cells. Using the successive ionic layer adsorption and reaction (SILAR) process, photoanodes are subjected to different amounts of CdS QD sensitization by varying the number of cycles of deposition. The sensitized electrodes are characterized using UV-visible spectroscopy, cyclic voltammetry and transmission electron microscopy to evaluate the extent of surface coverage of titania electrodes by QDs. Sandwich solar cells are then fabricated using these electrodes and characterized employing electrochemical impedance spectroscopy and J-V characteristics. It is observed that maximum solar cell efficiency is obtained for photoanodes with conformal coating of QDs and any further deposition of sensitizer leads to QD aggregation and so reduces the performance of the solar cells.

  6. Titania Nanostructures for Dye-sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    M Malekshahi Byranvand; A Nemati Kharat; M H Bazargan

    2012-01-01

    Titania is one kind of important materials, which has been extensively investigated because of its unique electronic and optical properties. Research efforts have largely focused on the optimization of the dye, but recently the titania nanostructures electrode itself has attracted more attention. It has been shown that particle size, shape, crystallinity, surface morphology, and chemistry of the TiO2 material are key parameters which should be controlled for optimized performance of the solar cell. Titania can be found in different shape of nanostructures including mesoporous, nanotube, nanowire, and nanorod structures. The present article reviews the structural, synthesis, electronic, and optical properties of TiO2 nanostructures for dye sensitized solar cells.

  7. M-Polynomials and Topological Indices of Titania Nanotubes

    Directory of Open Access Journals (Sweden)

    Mobeen Munir

    2016-10-01

    Full Text Available Titania is one of the most comprehensively studied nanostructures due to their widespread applications in the production of catalytic, gas sensing, and corrosion-resistant materials. M-polynomial of nanotubes has been vastly investigated, as it produces many degree-based topological indices, which are numerical parameters capturing structural and chemical properties. These indices are used in the development of quantitative structure-activity relationships (QSARs in which the biological activity and other properties of molecules, such as boiling point, stability, strain energy, etc., are correlated with their structure. In this report, we provide M-polynomials of single-walled titania (SW TiO2 nanotubes and recover important topological degree-based indices to theoretically judge these nanotubes. We also plot surfaces associated to single-walled titania (SW TiO2 nanotubes.

  8. Constructing Black Titania with Unique Nanocage Structure for Solar Desalination.

    Science.gov (United States)

    Zhu, Guilian; Xu, Jijian; Zhao, Wenli; Huang, Fuqiang

    2016-11-23

    Solar desalination driven by solar radiation as heat source is freely available, however, hindered by low efficiency. Herein, we first design and synthesize black titania with a unique nanocage structure simultaneously with light trapping effect to enhance light harvesting, well-crystallized interconnected nanograins to accelerate the heat transfer from titania to water and with opening mesopores (4-10 nm) to facilitate the permeation of water vapor. Furthermore, the coated self-floating black titania nanocages film localizes the temperature increase at the water-air interface rather than uniformly heating the bulk of the water, which ultimately results in a solar-thermal conversion efficiency as high as 70.9% under a simulated solar light with an intensity of 1 kW m(-2) (1 sun). This finding should inspire new black materials with rationally designed structure for superior solar desalination performance.

  9. Fabrication of hierarchically ordered crystalline titania thin films

    Energy Technology Data Exchange (ETDEWEB)

    Niedermeier, Martin; Kaune, Gunar; Rawolle, Monika; Koerstgens, Volker; Ruderer, Matthias; Mueller-Buschbaum, Peter [TU Muenchen, Physik-Department LS E13, Garching (Germany); Gutmann, Jochen S. [Max-Planck Institute for Polymer Research, Mainz (Germany)

    2010-07-01

    Thin films of nanostructured titania have received a lot of attention in various applications such as photovoltaics within the last years. Having a well defined morphology is crucial for the functionality and performance of these films because it defines the volume to surface ratio and thereby the surface being available for interface reactions. Increasing the total film thickness is a common approach in order to increase the surface area. The present work focuses on the fabrication of hierarchically structured titania thin films and their crystallinity. A layer-by-layer spin-coating approach is investigated. A solution based sol-gel process using diblock copolymers as a template to obtain nanocomposite films is followed by calcination to obtain crystalline titania structures. The obtained structures are investigated using several imaging techniques like SEM and AFM. The crystallinity and the thickness of the films are analyzed with XRD and XRR.

  10. Micromechanics Modeling of Fracture in Nanocrystalline Metals

    Science.gov (United States)

    Glaessgen, E. H.; Piascik, R. S.; Raju, I. S.; Harris, C. E.

    2002-01-01

    Nanocrystalline metals have very high theoretical strength, but suffer from a lack of ductility and toughness. Therefore, it is critical to understand the mechanisms of deformation and fracture of these materials before their full potential can be achieved. Because classical fracture mechanics is based on the comparison of computed fracture parameters, such as stress intlmsity factors, to their empirically determined critical values, it does not adequately describe the fundamental physics of fracture required to predict the behavior of nanocrystalline metals. Thus, micromechanics-based techniques must be considered to quanti@ the physical processes of deformation and fracture within nanocrystalline metals. This paper discusses hndamental physicsbased modeling strategies that may be useful for the prediction Iof deformation, crack formation and crack growth within nanocrystalline metals.

  11. Increased fibroblast functionality on CNN2-loaded titania nanotubes

    Directory of Open Access Journals (Sweden)

    Wei HB

    2012-02-01

    Full Text Available Hongbo Wei*, Shuyi Wu*, Zhihong Feng, Wei Zhou, Yan Dong, Guofeng Wu, Shizhu Bai, Yimin Zhao Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China *These authors contributed equally to this workAbstract: Infection and epithelial downgrowth are major problems associated with maxillofacial percutaneous implants. These complications are mainly due to the improper closure of the implant–skin interface. Therefore, designing a percutaneous implant that better promotes the formation of a stable soft tissue biologic seal around percutaneous sites is highly desirable. Additionally, the fibroblast has been proven to play an important role in the formation of biologic seals. In this study, titania nanotubes were filled with 11.2 kDa C-terminal CCN2 (connective tissue growth factor fragment, which could exert full CCN2 activity to increase the biological functionality of fibroblasts. This drug delivery system was fabricated on a titanium implant surface. CCN2 was loaded into anodized titania nanotubes using a simplified lyophilization method and the loading efficiency was approximately 80%. Then, the release kinetics of CCN2 from these nanotubes was investigated. Furthermore, the influence of CCN2-loaded titania nanotubes on fibroblast functionality was examined. The results revealed increased fibroblast adhesion at 0.25, 0.5, 1, 2, 4, and 24 hours, increased fibroblast viability over the course of 5 days, as well as enhanced actin cytoskeleton organization on CCN2-loaded titania nanotubes surfaces compared to uncoated, unmodified counterparts. Therefore, the results from this in vitro study demonstrate that CCN2-loaded titania nanotubes have the ability to increase fibroblast functionality and should be further studied as a method of promoting the formation of a stable soft tissue biologic seal around percutaneous sites.Keywords: anodization, titania nanotubes, adhesion, connective

  12. Charge Transfer in Nanocrystalline Semiconductor Electrodes

    Directory of Open Access Journals (Sweden)

    M. Bouroushian

    2013-01-01

    Full Text Available Nanocrystalline electrodes in liquid junction devices possess a number of unique properties arising from their convoluted structure and the dimensions of their building units. The light-induced charge separation and transport in photoelectrochemical systems using nanocrystalline/nanoporous semiconductor electrodes is discussed here in connection with the basic principles of the (Schottky barrier theory. Recent models for charge transfer kinetics in normal and unipolar (dye-sensitized cells are reviewed, and novel concepts and materials are considered.

  13. Photocatalytic composites based on titania nanoparticles and carbon nanomaterials

    Science.gov (United States)

    Nguyen, Bich Ha; Hieu Nguyen, Van; Vu, Dinh Lam

    2015-09-01

    In this article we present a review on recent experimental works toward the formation of visible light responsive composite photocatalysts on the basis of titania nanoparticles and carbon nanomaterials of different types. The research results achieved in last years has shown that the nanocomposite photocatalysts comprising titania nanoparticles and graphene or graphene oxide sheets, and also nanoparticles of noble metals and metallic oxides, exhibited the evident priority compared to the others. Therefore our review emphasizes the research on these promising visible light responsive nanophotocatalysts.

  14. Hierarchically structured titania films for application in photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Niedermeier, M.A.; Kaune, G.; Mueller-Buschbaum, P. [TU Muenchen, Garching (Germany). Lehrstuhl fuer Funktionelle Materialien; Perlich, J. [TU Muenchen, Garching (Germany). Lehrstuhl fuer Funktionelle Materialien; DESY, Hamburg (Germany). HASYLAB; Memesa, M. [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany); Gutmann, J.S. [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany); Mainz Univ. (Germany). Inst. fuer Physikalische Chemie

    2010-07-01

    The fabrication of nanostructured titania films is investigated. The nanostructures are prepared using the diblock copolymer polystyrene-block-polyethyleneoxide (P(S-b-EO)) as a structure directing agent. Using repetitive sol-gel chemistry together with spin coating a thin polymer-nanocomposite film is deposited on silicon substrates which is calcined in air to obtain crystalline titania nanostructures. Furthermore, different types of morphologies are combined. The thus obtained structures are investigated regarding their morphologies, for example using imaging techniques like SEM. Additionally, information about the crystallinity is obtained with XRD. From our results we discuss the use of our films for photovoltaic applications. (orig.)

  15. Comparison Study on the Microstructure of Nanocrystalline TiO2 in Different Ti-Si Binary Oxides

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Three different Ti-Si oxide structuares, silica supported titania, silica coated titania and intimately mixed silicatitania, containing 10%-40% SiO2, were made by sol-gel process. The variations of microstructure parameters of nanocrystalline (nc) TiO2-anatase in the three kirds of binary oxides, including in-plane spacing d, cell constants (a0, CQ), cell volume V, cell axial ratio c0/a0 and crystal grain size, were comparatively investigated by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). It is found that the microstructure parameters vary remarkably with increasing SiO2 content and annealing temperature. Different structured Ti-Si binary oxides lead to different variation tendencies of microstructure parameters. The more SiO2 the binary oxide contains, the more lattice defects of nc TiO2-anatase appear; diffusion or migration of Si cations could be an important influential factor in the variations of microstructure. The grain size of nc TiO2 in the three kinds of binary oxides not only depends on SiO2 content and annealing temperature but also on the degree of lattice microstrain and distortion of nc TiO2-anatase. Both grain size and phase transformation of nc TiO2-anatase are effectively inhibited with increasing SiOa content.

  16. Does nanocrystalline silver have a transferable effect?

    Science.gov (United States)

    Nadworny, Patricia L; Landry, Breanne K; Wang, JianFei; Tredget, Edward E; Burrell, Robert E

    2010-01-01

    This study examined the mechanism of nanocrystalline silver antiinflammatory activity, and tested nanocrystalline silver for systemic antiinflammatory effects. Secondary ion mass spectroscopy of skin treated directly with nanocrystalline silver for 24 hours showed that at skin surfaces there were significant deposits at weights corresponding to Ag, AgO, AgCl, AgNO(3), Ag(2)O, and silver clusters Ag(2-6), but silver penetration was minimal. To test for translocation of the effect, a porcine contact dermatitis model in which wounds were induced on one side of the back and then treated with nanocrystalline silver on the opposite side of the back was used. Visual and histological data showed improvement relative to animals treated with saline only. Significantly increased induction of apoptosis in the inflammatory cells present in the dermis was observed with remote nanocrystalline silver treatments. In addition, immunohistochemical analysis showed decreased levels of proinflammatory cytokines tumor necrosis factor-alpha and interleukin-8, and increased levels of antiinflammatory cytokine interleukin-4, epidermal growth factor, keratinocyte growth factor, and keratinocyte growth factor-2. Thus, the antiinflammatory effects of nanocrystalline silver appear to be induced by interactions with cells in the top layers of the skin, which then release biological signals resulting in widespread antiinflammatory activity.

  17. Control of Multilayer Networks

    CERN Document Server

    Menichetti, Giulia; Bianconi, Ginestra

    2015-01-01

    The controllability of a network is a theoretical problem of relevance in a variety of contexts ranging from financial markets to the brain. Until now, network controllability has been characterized only on isolated networks, while the vast majority of complex systems are formed by multilayer networks. Here we build a theoretical framework for the linear controllability of multilayer networks by mapping the problem into a combinatorial matching problem. We found that correlating the external signals in the different layers can significantly reduce the multiplex network robustness to node removal, as it can be seen in conjunction with a hybrid phase transition occurring in interacting Poisson networks. Moreover we observe that multilayer networks can stabilize the fully controllable multiplex network configuration that can be stable also when the full controllability of the single network is not stable.

  18. Controlling light with plasmonic multilayers

    DEFF Research Database (Denmark)

    Orlov, Alexey A.; Zhukovsky, Sergei; Iorsh, Ivan V.

    2014-01-01

    Recent years have seen a new wave of interest in layered media - namely, plasmonic multilayers - in several emerging applications ranging from transparent metals to hyperbolic metamaterials. In this paper, we review the optical properties of such subwavelength metal-dielectric multilayered...... metamaterials and describe their use for light manipulation at the nanoscale. While demonstrating the recently emphasized hallmark effect of hyperbolic dispersion, we put special emphasis to the comparison between multilayered hyperbolic metamaterials and more broadly defined plasmonic-multilayer metamaterials...

  19. Plastic deformation of nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A high-resolution electron microscopy study has uncovered the plastic behavior of accommodating large strains in nanocrystalline (NC) Ni subject to cold rolling at liquid nitrogen temperature. The activation of grain-boundary-mediated-plasticity is evidenced in NC-Ni, including twinning and formation of stacking fault via partial dislocation slips from the grain boundary. The formation and storage of 60? full dislocations are observed inside NC-grains. The grain/twin boundaries act as the barriers of dislocation slips, leading to dislocation pile-up, severe lattice distortion, and formation of sub-grain boundary. The vicinity of grain/twin boundary is where defects preferentially accumulate and likely the favorable place for onset of plastic deformation. The present results indicate the heterogeneous and multiple natures of accommodating plastic strains in NC-grains.

  20. Plastic deformation of nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    WU XiaoLei

    2009-01-01

    A high-resolution electron microscopy study has uncovered the plastic behavior of accommodating large strains in nanocrystalline(NC)Ni subject to cold rolling at liquid nitrogen temperature.The acti vation of grain-boundary-mediated-plasticity is evidenced in NC-Ni,including twinning and formation of stacking fault via partial dislocation slips from the grain boundary.The formation and storage of 60° full dislocations are observed inside NC-grains.The grain/twin boundaries act as the barriers of dislocation slips,leading to dislocation pile-up,severe lattice distortion,and formation of sub-grain boundary.The vicinity of grain/twin boundary is where defects preferentially accumulate and likely the favorable place for onset of plastic deformation.The present results indicate the heterogeneous and multiple natures of accommodating plastic strains in NC-grains.

  1. Multilayer Social Networks

    DEFF Research Database (Denmark)

    Dickison, Mark; Magnani, Matteo; Rossi, Luca

    social network systems, the evolution of interconnected social networks, and dynamic processes such as information spreading. A single real dataset is used to illustrate the concepts presented throughout the book, demonstrating both the practical utility and the potential shortcomings of the various......Multilayer networks, in particular multilayer social networks, where users belong to and interact on different networks at the same time, are an active research area in social network analysis, computer science, and physics. These networks have traditionally been studied within these separate...

  2. Synthesis and polymorphic control for visible light active titania nanoparticles

    Science.gov (United States)

    Kaewgun, Sujaree

    Titania (TiO2) is useful for many applications in photocatalysis, antimicrobials, pigment, deodorization, and decomposition of harmful organics and undesirable compounds in the air and waste water under UV irradiation. Among the three phases of TiO2, Rutile, Anatase, and Brookite, studies have been more focused on the anatase and rutile phases. Pure brookite is the most difficult phase to prepare, even under hydrothermal conditions. Predominantly brookite phase TiO2 nanoparticles were prepared by the Water-based Ambient Condition Sol (WACS) process in our laboratory. The objectives of this research were to enhance visible light active (VLA) photocatalytic properties of polymorphic brookite TiO2 by minimizing the lattice defects and narrowing band gap of titania by nitrogen and/or carbon chromophone, and to investigate the deactivation, reusability, and regeneration of the VLA titania in order to design better titania catalysts for organic compound degradation applications. In order to study the influence of hydroxyl content on photocatalytic activities (PCAs) of polymorphic titania nanoparticles, the WACS samples were post-treated by a Solvent-based Ambient Condition Sol (SACS) process in sec-butanol (sec-BuOH). All samples were characterized for phase composition, surface area, hydroxyl contamination, and particle morphology by x-ray diffraction, N2 physisorption, FT-IR, solid state 1H NMR and scanning electron microscopy, and then compared to a commercial titania, Degussa P25. Evaluation of methyl orange (MO) degradation under UV irradiation results showed that the lower lattice hydroxyl content in SACS titania enhanced the PCA. As-prepared titania and SACS samples, which have similar surface areas and crystallinity, were compared in order to prove that the superior PCA came from the reduction in the lattice hydroxyl content. To enhance PCA and VLA properties of WACS, an alternative high boiling point polar solvent, N-methylpyrrolidone (NMP), was utilized in the

  3. Synthesis and micro structural investigations of titania-silica nano composite aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Ingale, S.V., E-mail: svingale@barc.gov.in [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sastry, P.U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Wagh, P.B. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tripathi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Rao, R. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tewari, R. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Rao, P.T. [Powder Metallurgy Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Patel, R.P. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2012-08-15

    We have synthesized titania-silica (TiO{sub 2}-SiO{sub 2}) aerogel composites with 20 wt%, 50 wt% and 65 wt% TiO{sub 2} by sol-gel method and investigated their microstructure in detailed using variety of techniques. X-ray diffraction showed formation of the anatase phase of TiO{sub 2} in nano-crystalline form which was confirmed by the broadening of Raman spectra. FTIR studies indicated that TiO{sub 2} is structurally incorporated in to the lattice of silica with formation of the Si-O-Ti linkage. Small angle X-ray scattering study indicated the presence of larger aggregates with rough surfaces. A systematic variation in the morphology of the larger grains and constituting smaller particles (of typical size about 20 nm) with increase in TiO{sub 2} content has been noticed. Pictures from TEM indicated that TiO{sub 2} is confined to the pores in the host silica gel, resulting in formation of TiO{sub 2} nano-crystallites leading to high surface area. Nitrogen-physisorption studies further confirmed that the TiO{sub 2} particles occupy the pores of gel matrix resulting in reduction in the average pore diameter with increasing TiO{sub 2} content. The results from all the techniques clearly suggested that the variations in the microstructure of the composites as prepared by sol-gel method will have significant impact on the optical and catalytic performance of the TiO{sub 2}. -- Highlights: Black-Right-Pointing-Pointer Synthesized successfully TiO{sub 2}-SiO{sub 2} composite aerogels containing up to 65 wt% TiO{sub 2}. Black-Right-Pointing-Pointer Detailed micro structural study to investigate effects of increasing TiO{sub 2} content. Black-Right-Pointing-Pointer Correlated optical and catalytic properties with microstructure of the nano-composites.

  4. Nanocrystalline cellulose from coir fiber: preparation, properties, and applications

    Science.gov (United States)

    Nanocrystalline cellulose derived from various botanical sources offers unique and potentially useful characteristics. In principle, any cellulosic material can be considered as a potential source of a nanocrystalline material, including crops, crop residues, and agroindustrial wastes. Because of t...

  5. Synthesis and Characterization of Titania and Rare Earth Doped Titania Nanoparticles by Sol-gel Process

    Institute of Scientific and Technical Information of China (English)

    LIN Ping; XIAN Chun-ying; MAO Zhi-ping; ZHENG Li-min

    2006-01-01

    Titania sol has been prepared by the sol-gel process with Ti(OC4H9)4 as precursor. TiO2 gel was obtained through hydrolysis and condensation process. Rare earth such as La2O3, CeO2 and Gd2O3 were introduced into the nanostructure TiO2. After TiO2 and rare earth doped TiO2powders were calcined at 400℃, 500℃, 600℃, 700℃ and 800℃ respectively, the characteristic analyses of the TiO2samples were studied by UV-VIS, XRD and TEM etc. It was found that there are some stronger absorption peaks at 200- 325 nm. The rare earth doping can increase the phase transition temperature converting anatase phase into ruttle phase, can decrease the grain size of TiO2particles and can improve the ant1-UV capacity of the coating fabrics.

  6. Hydrothermal synthesis of nanostructured titania; Sintese hidrotermica de ceramicas de titania nanoestruturada

    Energy Technology Data Exchange (ETDEWEB)

    Yoshito, W.K.; Ferreira, N.A.M.; Lazar, D.R.R.; Ussui, V., E-mail: wkyoshito@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Rumbao, A.C.S. [Universidade Presbiteriana Mackenzie (UPM), Sao Paulo, SP (Brazil)

    2011-07-01

    Titania ceramics have many applications due to its surface properties and, recently, its nanostructured compounds, prepared by hydrothermal treatments, have been described to improve these properties. In this work, commercial titanium dioxide was treated with 10% sodium hydroxide solution in a pressurized reactor at 150 deg C for 24 hours under vigorous stirring and then washed following two different procedures. The first one consisted of washing with water and ethanol and the second with water and hydrochloric acid solution (1%). Resulting powders were characterized by X-ray diffraction, N{sub 2} gas adsorption and field emission gun scanning and transmission electronic microscopy. Results showed that from an original starting material with mainly rutile phase, both anatase and H{sub 2}Ti{sub 3}O{sub 7} phase could be identified after the hydrothermal treatment. Surface area of powders presented a notable increase of one order of magnitude and micrographs showed a rearrangement on the microstructure of powders. (author)

  7. Anodically Grown Titania Nanotube Induced Cytotoxicity has Genotoxic Origins

    Science.gov (United States)

    Mohamed, M. Sheikh; Torabi, Aida; Paulose, Maggie; Kumar, D. Sakthi; Varghese, Oomman K.

    2017-02-01

    Nanoarchitectures of titania (TiO2) have been widely investigated for a number of medical applications including implants and drug delivery. Although titania is extensively used in the food, drug and cosmetic industries, biocompatibility of nanoscale titania is still under careful scrutiny due to the conflicting reports on its interaction with cellular matter. For an accurate insight, we performed in vitro studies on the response of human dermal fibroblast cells toward pristine titania nanotubes fabricated by anodic oxidation. The nanotubes at low concentrations were seen to induce toxicity to the cells, whereas at higher concentrations the cell vitality remained on par with controls. Further investigations revealed an increase in the G0 phase cell population depicting that majority of cells were in the resting rather than active phase. Though the mitochondrial set-up did not exhibit any signs of stress, significantly enhanced reactive oxygen species production in the nuclear compartment was noted. The TiO2 nanotubes were believed to have gained access to the nuclear machinery and caused increased stress leading to genotoxicity. This interesting property of the nanotubes could be utilized to kill cancer cells, especially if the nanotubes are functionalized for a specific target, thus eliminating the need for any chemotherapeutic agents.

  8. Structure transition of nano-titania during calcination

    Institute of Scientific and Technical Information of China (English)

    李国华; 王大伟; 徐铸德; 陈卫祥

    2003-01-01

    In order to study the structure transition during calcination, nano-titania powders prepared by hydrolyzing precipitation approach and calcined at 300, 400, 500, 600 and 700 ℃ were characterized by XRD, TEM and electron diffraction(ED), respectively. The results show that titania powders calcined below 500 ℃ are almost composed of anatase, rutile appears below 500 ℃ and its ratio increases gradually with increase of calcin temperature;nano-titania particles are smaller than 40 nm mostly and the dispersion is related to calcining temperature; the interplanar distances of nano-anatase single crystalline change gradually when calcing temperature increases to 500 ℃; so do that of nano-rutile single crystalline when calcining temperature charges from 600 to 700 ℃. The conclusions can be drawn that the temperature of transformation from anatase to rutile is below 500 ℃ and the process carries on gradually. Both inter-planar distances and the structure of nano-titania transform gradually with increasing calcing temperature.

  9. Ti3+-containing titania: Synthesis tactics and photocatalytic performance

    NARCIS (Netherlands)

    Saputera, W.H.; Mul, G.; Hamdy, Mohamed S.

    2015-01-01

    Three different synthesis techniques were applied to prepare Ti3+-containing TiO2. The first is a self-doped technique in which TiO2 was reduced in situ at 500 °C by NO and CO gases to produce blue powder (blue titania). The second method is a calcination treatment of a physical mixture consisting o

  10. Electro spraying of titania for nitrogen oxide abatement

    NARCIS (Netherlands)

    Ursem, W.N.J.; Marijnissen, J.C.; Roos, R.A.; Kelder, E.M.

    2010-01-01

    The invention provides a method for the production of a titania coating (80) on a surface (101) of an object (100) comprising electro spraying a titanium comprising liquid (15) to the surface (101) of the object (100) to provide a titanium comprising layer (85); and heating thetitanium comprising la

  11. Titania nanotube arrays as interfaces for neural prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Sorkin, Jonathan A. [Department of Mechanical Engineering, Colorado State University, Fort Collins CO 80523 (United States); Hughes, Stephen [Department of Chemical and Biological Engineering, Colorado State University, Fort Collins CO 80523 (United States); School of Biomedical Engineering, Colorado State University, Fort Collins CO 80523 (United States); Soares, Paulo [Department of Mechanical Engineering, Polytechnic School, Pontifícia Universidade Católica do Paraná, Curitiba, PR 80215-901 (Brazil); Popat, Ketul C., E-mail: ketul.popat@colostate.edu [Department of Mechanical Engineering, Colorado State University, Fort Collins CO 80523 (United States); School of Biomedical Engineering, Colorado State University, Fort Collins CO 80523 (United States)

    2015-04-01

    Neural prostheses have become ever more acceptable treatments for many different types of neurological damage and disease. Here we investigate the use of two different morphologies of titania nanotube arrays as interfaces to advance the longevity and effectiveness of these prostheses. The nanotube arrays were characterized for their nanotopography, crystallinity, conductivity, wettability, surface mechanical properties and adsorption of key proteins: fibrinogen, albumin and laminin. The loosely packed nanotube arrays fabricated using a diethylene glycol based electrolyte, contained a higher presence of the anatase crystal phase and were subsequently more conductive. These arrays yielded surfaces with higher wettability and lower modulus than the densely packed nanotube arrays fabricated using water based electrolyte. Further the adhesion, proliferation and differentiation of the C17.2 neural stem cell line was investigated on the nanotube arrays. The proliferation ratio of the cells as well as the level of neuronal differentiation was seen to increase on the loosely packed arrays. The results indicate that loosely packed nanotube arrays similar to the ones produced here with a DEG based electrolyte, may provide a favorable template for growth and maintenance of C17.2 neural stem cell line. - Highlights: • Titania nanotube arrays can be fabricated with to have loosely or densely packed morphologies. • Titania nanotube arrays support higher C17.2 neural stem cell adhesion and proliferation. • Titania nanotube arrays support higher C17.2 neural stem cell differentiation towards neuronal lineage.

  12. Adsorption of graft copolymers onto silica and titania.

    NARCIS (Netherlands)

    Bijsterbosch, H.D.; Cohen Stuart, M.A.; Fleer, G.J.

    1998-01-01

    The adsorption of graft copolymers of poly(acrylamide) (PAAm, backbone) and poly(ethylene oxide) (PEO, side chains) from aqueous solution onto silica and titania was studied with reflectometry. Two high-molar-mass copolymers were used with different PEO graft densities (10 and 18% w/w PEO in copolym

  13. Ethylene glycol-assisted coating of titania on nanoparticles.

    Science.gov (United States)

    Dahl, Michael; Castaneda, Fernando; Joo, Ji Bong; Reyes, Victor; Goebl, James; Yin, Yadong

    2016-06-14

    Coating titania shells onto sub-micron sized particles has been widely studied recently, with success mainly limited to objects with sizes above 50 nm. Direct coating on particles below this size has been difficult to attain especially with good control over properties such as thickness and crystallinity. Here we demonstrate that titanium-glycolate formed by reacting titanium alkoxide and ethylene glycol is an excellent precursor for coating titania on aqueous nanoparticles. The new coating method is particularly useful for its ability to coat materials lacking strong polymers or ligands which are frequently needed to facilitate typical titania coatings. We demonstrate the effectiveness of the process of coating titania on metal nanoparticles ranging from citrate-stabilized gold and silver spheres to gold nanorods and silver nanoplates, and larger particles such as SiO2 microspheres and polymer spheres. Further the thickness of these coatings can be tuned from a few nanometers to ∼40 nm through sequential coatings. These coatings can subsequently be crystallized into TiO2 through refluxing in water or by calcination to obtain crystalline shells. This procedure can be very useful for the production of TiO2 coatings with tunable thickness and crystallinity as well as for further study on the effect of TiO2 coatings on nanoparticles.

  14. Screening in multilayer graphene

    NARCIS (Netherlands)

    van Gelderen, R.; Olsen, Richard; de Morais Smith, C.

    2013-01-01

    In this paper, we study the static polarization in ABC-stacked multilayer graphene. Since the density of states diverges for these systems if the number of layers exceeds three, screening effects are expected to be important. In the random phase approximation, screening can be included through the p

  15. Preparation, Characterization, and Enhanced Thermal and Mechanical Properties of Epoxy-Titania Composites

    Science.gov (United States)

    Rubab, Zakya; Siddiqi, Humaira M.; Saeed, Shaukat

    2014-01-01

    This paper presents the synthesis and thermal and mechanical properties of epoxy-titania composites. First, submicron titania particles are prepared via surfactant-free sol-gel method using TiCl4 as precursor. These particles are subsequently used as inorganic fillers (or reinforcement) for thermally cured epoxy polymers. Epoxy-titania composites are prepared via mechanical mixing of titania particles with liquid epoxy resin and subsequently curing the mixture with an aliphatic diamine. The amount of titania particles integrated into epoxy matrix is varied between 2.5 and 10.0 wt.% to investigate the effect of sub-micron titania particles on thermal and mechanical properties of epoxy-titania composites. These composites are characterized by X-ray photoelectron (XPS) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric (TG), and mechanical analyses. It is found that sub-micron titania particles significantly enhance the glass transition temperature (>6.7%), thermal oxidative stability (>12.0%), tensile strength (>21.8%), and Young's modulus (>16.8%) of epoxy polymers. Epoxy-titania composites with 5.0 wt.% sub-micron titania particles perform best at elevated temperatures as well as under high stress. PMID:24578638

  16. Fabrication of titania thin film with composite nanostructure and its ability to photodegrade rhodamine B in water

    Institute of Scientific and Technical Information of China (English)

    Gaojie ZHANG; Jinming WU; Shaoguang LIU; Mi YAN

    2008-01-01

    A titania nanorod film was synthesized by direct oxidation of metallic Ti with hydrogen peroxide solution under a low temperature. Titania nanoparticles were then filled into the gaps among the nanorods through an infiltration sol-gel procedure to form a composite titania film with an ordered nanostructure. X-ray diffraction spectra indicate that the composite film was a mixture of anatase and rutile while the titania film obtained by only using a sol-gel procedure was pure anatase. Field emission scanning electron microscopy observations show that titania nanoparticles were embedded into the titania nanorod film. Photoluminescence spectra suggest the enhanced separation of electron and hole pairs for the obtained composite titania film over the corresponding titania nanorod film. The composite titania film exhibited improved ability to photodegrade rhodamine B in water compared with the titania nanorod film. The apparent photodegradation rate constant, fitting a pseudo-first-order, was 3 times of that obtained by the sol-gel derived titania film at the same weight. The improved photocata-lytic activity for the composite titania film could be attributed to the enhanced separation of electron and hole pairs due to the embedding of the titania nanoparticles within the titania nanorods.

  17. Comparison of the Structural Configuration of Cobalt Nanoparticles on Titania and Titania Nanotube Supports

    Directory of Open Access Journals (Sweden)

    E. Muzenda

    2012-03-01

    Full Text Available In this study, two cobalt based catalyst samples were prepared on titania and titania nanotubes supports using the deposition precipitation method. Their structural configurations were characterized and compared using BET, and TRP analyses. The BET analysis showed that the surface area of TiO2 is much higher than that of TNT which was due to their structural differences. Analyses of the results obtained revealed that the surface area of the 10 % Co/TNT catalyst sample is higher than that of the 10 % Co/TiO2. The TPR analysis showed that it is much easier to reduce 10 % Co/TiO2, than 10 % Co/TNT. This is attributed to be due to the fact that the cobalt particles were adsorbed on the surface of the TiO2, and formed covalent bonds with TNT. Therefore reduction temperature was higher with TNT than TiO2. The investigation of structural changes of these catalysts when they were coated with carbon, using chemical vapour deposition method was also conducted. The catalyst prepared on TNT support showed better properties in terms of average pore diameter, pore volume and surface area than the catalyst sample prepared on TiO2 support when the two samples were exposed to carbon environment for the same period of time. In this study, two cobalt based catalyst samples were prepared on titania and titania nanotubes supports using the deposition precipitation method. Their structural configurations were characterized and compared using BET, and TRP analyses. The BET analysis showed that the surface area of TiO2 is much higher than that of TNT which was due to their structural differences. Analyses of the results obtained revealed that the surface area of the 10 % Co/TNT catalyst sample is higher than that of the 10 % Co/TiO2. The TPR analysis showed that it is much easier to reduce 10 % Co/TiO2, than 10 % Co/TNT. This is attributed to be due to the fact that the cobalt particles were adsorbed on the surface of the TiO2, and formed covalent bonds

  18. Integration of High-Performance Nanocrystalline TiO2 Photoelectrodes for N719-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Ke-Jian Jiang

    2013-01-01

    Full Text Available We report on enhanced performance of N719-sensitized TiO2 solar cells (DSCs incorporating size and photoelectron diffusion-controlled TiO2 as sensitizer-matched light-scatter layers on conventional nanocrystalline TiO2 electrodes. The double-layered N719/TiO2 composite electrode with a high dye-loading capacity exhibits the diffused reflectance of more than 50% in the range of λ = 650–800 nm, even when the films are coupled with the titania nanocrystalline underlayer in the device. As a result, the increased near-infrared light-harvesting produces a high light-to-electricity conversion efficiency of over 9% mainly due to the significant increase of Jsc. Such an optical effect of the NIR-light scattering TiO2 electrodes will be beneficial when the sensitizers with low molar extinction coefficients, such as N719, are introduced in the device.

  19. Structural elucidation of nanocrystalline biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Maltsev, S.

    2008-10-23

    Bone diseases, such as osteoporosis and osteoarthritis, are the second most prevalent health problem worldwide. In Germany approximately 5 millions people are affected by arthritis. Investigating biomineralization processes and bone molecular structure is of key importance for developing new drugs for preventing and healing bone diseases. Nuclear magnetic resonance (NMR) was the primary technique used due to its advantages in characterising poorly ordered and disordered materials. Compared to all the diffraction techniques that widely applied in structural investigations, the usefulness of NMR is independent of long range molecular order. This makes NMR an outstanding technique for studies of complex/amorphous materials. Conventional NMR experiments (single pulse, spin-echo, cross polarization (CP), etc.) as well as their modifications and high-end techniques (2D HETCOR, REDOR, etc.) were used in this work. Combining the contributions from different techniques enhances the information content of the investigations and can increase the precision of the overall conclusions. Also XRD, TEM and FTIR were applied to different extent in order to get a general idea of nanocrystalline hydroxyapatite crystallite structure. Results: - A new approach named 'Solid-state NMR spectroscopy using the lost I spin magnetization in polarization transfer experiments' has been developed for measuring the transferred I spin magnetization from abundant nuclei, which is normally lost when detecting the S spin magnetization. - A detailed investigation of nanocrystalline hydroxyapatite core was made to prove that proton environment of the phosphates units and phosphorus environment of hydroxyl units are the same as in highly crystalline hydroxyapatite sample. - Using XRD it was found that the surface of the hydroxyapatite nanocrystals is not completely disordered, as it was suggested before, but resembles the hydroxyapatite structure with HPO{sub 4}{sup 2-} (and some CO{sub 3}{sup

  20. Seeded growth of titania colloids with refractive index tunability and fluorophore-free luminescence.

    Science.gov (United States)

    Demirörs, Ahmet Faik; Jannasch, Anita; van Oostrum, Peter D J; Schäffer, Erik; Imhof, Arnout; van Blaaderen, Alfons

    2011-03-01

    Titania is an important material in modern materials science, chemistry, and physics because of its special catalytic, electric, and optical properties. Here, we describe a novel method to synthesize colloidal particles with a crystalline titania, anatase core and an amorphous titania-shell structure. We demonstrate seeded growth of titania onto titania particles with accurate particle size tunability. The monodispersity is improved to such an extent so that colloidal crystallization of the grown microspheres becomes feasible. Furthermore, seeded growth provides separate manipulation of the core and shell. We tuned the refractive index of the amorphous shell between 1.55 and 2.3. In addition, the particles show luminescence when trace amounts of aminopropyl-triethoxysilane are incorporated into the titania matrix and are calcined at 450 °C. Our novel colloids may be useful for optical materials and technologies such as photonic crystals and optical trapping.

  1. Direct coating of mesoporous titania on CTAB-capped gold nanorods

    Science.gov (United States)

    Zhao, Junwei; Xu, Pengyu; Li, Yue; Wu, Jian; Xue, Junfei; Zhu, Qiannan; Lu, Xuxing; Ni, Weihai

    2016-03-01

    We demonstrate a CTAB-templated approach towards direct coating of mesoporous titania on gold nanorods in aqueous solutions. The formation of the mesoporous shell is found to be closely correlated with CTAB concentration and the amount of the titania precursor. This approach can be readily extended to form mesoporous titania shells on other CTAB-capped nanoparticles.We demonstrate a CTAB-templated approach towards direct coating of mesoporous titania on gold nanorods in aqueous solutions. The formation of the mesoporous shell is found to be closely correlated with CTAB concentration and the amount of the titania precursor. This approach can be readily extended to form mesoporous titania shells on other CTAB-capped nanoparticles. Electronic supplementary information (ESI) available: Experimental details including chemicals, sample preparation, and characterization methods. UV-Vis extinction spectra, SEM images, and TEM images of AuNR@mTiO2 nanostructures. See DOI: 10.1039/c5nr05692f

  2. Laser-ablated titania nanoparticles for aqueous processed hybrid solar cells

    Science.gov (United States)

    Körstgens, V.; Pröller, S.; Buchmann, T.; Moseguí González, D.; Song, L.; Yao, Y.; Wang, W.; Werhahn, J.; Santoro, G.; Roth, S. V.; Iglev, H.; Kienberger, R.; Müller-Buschbaum, P.

    2015-02-01

    Titania nanoparticles are produced by laser ablation in liquid in order to initiate functionalization of titania with the polymer for the active layer. By combining these titania nanoparticles and water-soluble poly[3-(potassium-6-hexanoate)thiophene-2,5-diyl] (P3P6T) hybrid solar cells are realized.Titania nanoparticles are produced by laser ablation in liquid in order to initiate functionalization of titania with the polymer for the active layer. By combining these titania nanoparticles and water-soluble poly[3-(potassium-6-hexanoate)thiophene-2,5-diyl] (P3P6T) hybrid solar cells are realized. Electronic supplementary information (ESI) available: Full scheme of the production of solar cells, additional spectra and details of the measurement techniques. See DOI: 10.1039/c4nr06782g

  3. X-ray studies of ion adsorption at charged titania-electrolyte interfaces

    Science.gov (United States)

    Kohli, Vaibhav

    Interaction of counter ions with charged solid-electrolyte interfaces plays an important role in wide ranging chemical and environmental processes including ion adsorption, colloidal stability, and electrokinetic transport. A complete molecular-level characterization of the counter-ion profile near the interface is critical to understanding the interfacial reactivity. Resonant anomalous X-ray reflectivity (RAXR), and crystal truncation rod (CTR) techniques were used to directly measure the vertical density profiles of Rb+ and Sr2+ at the rutile TiO2(110)-electrolyte interface. These results are the first experimental confirmation of a recent molecular dynamics prediction that the adsorbed ion structure is distributed between multiple inner-sphere sites (i.e., tetra-dentate and bi-dentate) rather than a single site (i.e., tetra-dentate) as thought from previous investigations. Rb+ and Sr2+ are found to be specifically-adsorbed with coverages of 0.080+/-0.003 and 0.40+/-0.07 monolayers respectively, and average heights of 3.72+/-0.03 A and 3.05+/-0.16 A above the interface respectively. A new generalized model-independent approach was developed for the analysis of long-period x-ray standing waves (XSW) data. The approach is applicable to various reflection geometries, including simple x-ray mirrors, and multi-layers, and is valid for XSW in an attenuating medium. The formalism allows direct extraction of the amplitudes and phases of the elemental structure factor from the measured long-period XSW data, leading to a fully model-independent recovery of the elemental distribution. The method is demonstrated by extracting the 1D profile of Ti normal to the surface for a TiO2/Si/Mo tri-layer sample on a Si substrate, using Ti-Kalpha fluorescence yield measured in ex situ and in situ environments. Using long period XSW, X-ray fluorescence (XRF) and X-ray reflectivity (XR), it is shown that titania nanofilms grown by atomic layer deposition (ALD) exhibit significantly

  4. Surface Features of Nanocrystalline Alloys

    Directory of Open Access Journals (Sweden)

    Marcel Miglierini

    2015-12-01

    Full Text Available Nanocrystalline alloys are prepared by controlled annealing of metallic glass precursors. The latter are obtained by rapid quenching of a melt on a rotating wheel. This process leads to structural deviation of the produced ribbons’ surfaces. Structural features of as-quenched and thermally annealed 57Fe81Mo8Cu1B10 ribbons were studied employing Conversion Electron Mössbauer Spectrometry (CEMS and Conversion X-ray Mössbauer Spectrometry (CXMS. Enrichment of the alloy’s composition in 57Fe helped in identification of surface crystallites that were formed even during the production process. Magnetite and bcc-Fe were found at the wheel side of the as-quenched ribbons whereas only bcc-Fe nanocrystals were uncovered at the opposite air side. Accelerated formation of bcc-Fe was observed in this side of the ribbons after annealing. The relative content of magnetite at the wheel side was almost stable in near surface areas (CEMS and in more deep subsurface regions (CXMS. It vanished completely after annealing at 550 °C. No magnetite was observed at the air side of the ribbons regardless the annealing temperature and/or depth of the scanned regions.

  5. Consolidation of nanocrystalline hydroxyapatite powder

    Directory of Open Access Journals (Sweden)

    S. Ramesh et al

    2007-01-01

    Full Text Available The effect of sintering temperature on the sinterability of synthesized nanocrystalline hydroxyapatite (HA was investigated. The starting powder was synthesized via a novel wet chemical route. HA green compacts were prepared and sintered in atmospheric condition at various temperatures ranging from 900–1300 °C. The results revealed that the thermal stability of HA phase was not disrupted throughout the sintering regime employed. In general, the results showed that above 98% of theoretical density coupled with hardness of 7.21 GPa, fracture toughness of 1.17 MPa m1/2 and Young's modulus of above 110 GPa were obtained for HA sintered at temperature as low as 1050 °C. Although the Young's modulus increased with increasing bulk density, the hardness and fracture toughness of the sintered material started to decline when the temperature was increased beyond 1000–1050 °C despite exhibiting high densities >98% of theoretical value. The occurrence of this phenomenon is believed to be associated with a thermal-activated grain growth process.

  6. Development of a dielectric ceramic based on diatomite-titania part two: dielectric properties characterization

    Directory of Open Access Journals (Sweden)

    Medeiros Jamilson Pinto

    1998-01-01

    Full Text Available Dielectric properties of sintered diatomite-titania ceramics are presented. Specific capacitance, dissipation factor, quality factor and dielectric constant were determined as a function of sintering temperature, titania content and frequency; the temperature coefficient of capacitance was measured as a function of frequency. Besides leakage current, the dependence of the insulation resistance and the dielectric strength on the applied dc voltage were studied. The results show that diatomite-titania compositions can be used as an alternative dielectric.

  7. Preparation and thermal decomposition mechanism of Mg,Al-hydrotalcite nano-crystals with titania doping

    Institute of Scientific and Technical Information of China (English)

    REN Qing-li; LUO Qiang

    2006-01-01

    The highly pure nano-crystal Mg,Al-hydrotalcite with titania doping was synthesized by one-step liquid reaction method at atmospheric pressure. The preparation of the Mg,Al-hydrotalcite nano-crystal after doping titania was investigated according to the results of XRD,TEM,IR and DSC. Moreover,based on the DSC test results,the thermal mechanism functions of the Mg,Al-hydrotalcite with titania doping were studied after calculation and comparison.

  8. Combustion synthesis of bulk nanocrystalline iron alloys

    Directory of Open Access Journals (Sweden)

    Licai Fu

    2016-02-01

    Full Text Available The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on the synthesis of nanocrystalline metals and alloys prepared by combustion synthesis technique are reviewed. Then, the mechanical and tribological properties of these materials with microstructure control are discussed.

  9. Combustion synthesis of bulk nanocrystalline iron alloys

    Institute of Scientific and Technical Information of China (English)

    Licai Fu; Jun Yang; Weimin Liu

    2016-01-01

    The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on the synthesis of nanocrystalline metals and alloys prepared by combustion synthesis technique are reviewed. Then, the mechanical and tribological properties of these materials with microstructure control are discussed.

  10. Properties and Application of Nanocrystalline Poly (vinyl chloride)

    Institute of Scientific and Technical Information of China (English)

    Chuanxi XIONG; Hong YANG; Lijie DONG; Qihong LIU; Qingmin LIU

    2004-01-01

    The structure and properties of nanocrystalline PVC were investigated. The crystalline region of nanocrystalline PVC was observed by TEM to be 80 nm. The melting point of nanocrystalline PVC was found to be 128℃ which is obviously lower than typical PVC (210℃). The X-ray diagram indicated that the crystal existed in nanocrystalline PVC. The evident effect of self-plasticizing and reinforcement appeared when nanocrystalline PVC was added. The optimum amount for self-plasticizing is about 10%. The maximal impact strength of 95.1 kJ/m2 was achieved by adding 20% nanocrystalline PVC and tensile strength with 56.2 MPa which was 122% of pure PVC was obtained after adding 5% nanocrystalline PVC.

  11. Monolithic 3D titania with ultrathin nanoshell structures for enhanced photocatalytic activity and recyclability

    Science.gov (United States)

    Ahn, Changui; Park, Junyong; Kim, Donghyuk; Jeon, Seokwoo

    2013-10-01

    Titania has attracted considerable interest for use in water purification applications due to its excellent photocatalytic activity. To further improve the efficiency of photocatalysis, numerous nanostructures (i.e. nanoparticles, nanotubes, and nanowires) have been proposed to increase the surface area of titania. Despite the high photocatalytic performance of the nanostructured titania, subsequent difficulties encountered in recollection and reuse of titania inhibit the practical application for water purification systems. Here we successfully fabricate monolithic, three dimensional (3D) nanoshell titania with high uniformity over large areas (~1 × 1 inch2) through proximity field nanopatterning (PnP) and low-temperature atomic layer deposition (ALD) techniques. The higher surface area of 3D nanoshell titania increases the photocatalytic performance more than three-fold relative to that of a thin film of equivalent sample size. Also, the monolithic form of titania enables it to be reused without any degradation of photocatalytic activity. The newly developed nanomaterials in this study can serve as an efficient and reusable photocatalyst for water purification systems.Titania has attracted considerable interest for use in water purification applications due to its excellent photocatalytic activity. To further improve the efficiency of photocatalysis, numerous nanostructures (i.e. nanoparticles, nanotubes, and nanowires) have been proposed to increase the surface area of titania. Despite the high photocatalytic performance of the nanostructured titania, subsequent difficulties encountered in recollection and reuse of titania inhibit the practical application for water purification systems. Here we successfully fabricate monolithic, three dimensional (3D) nanoshell titania with high uniformity over large areas (~1 × 1 inch2) through proximity field nanopatterning (PnP) and low-temperature atomic layer deposition (ALD) techniques. The higher surface area of 3D

  12. Preparation and characterization of perfluorosulfonic resin/titania hybrid transparent films

    Institute of Scientific and Technical Information of China (English)

    LI JianMei; XUE MinZhao; ZHANG YongMing; LIU YanGang

    2007-01-01

    Preparation and characterization of perfluoroaulfonic resin/titaniaorganic-inorganic hybrid films were presented. The transparent hybrid films were prepared by hydrothermal treatment at low temperature of a mixed solution of tetrabutyl titanata and perfluorosulfonic resin with the help of acetylacetone. The charactarization was carried out by SEM, XRD, FT-IR, UV-Vis and TGA. The results showed that the perfiuorosulfonic resin/titania hybrid transparent films were composed of titania particles dispersed in the perfluorosulfonic resin matrix very well and the titania was of anatase phase. Its diameter decreased with increasing weight ratio of titania to perfluorosulfonic resin.

  13. Combustion synthesis of bulk nanocrystalline iron alloys

    OpenAIRE

    Licai Fu; Jun Yang; Weimin Liu

    2016-01-01

    The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on...

  14. Ultrafast Terahertz Conductivity of Photoexcited Nanocrystalline Silicon

    DEFF Research Database (Denmark)

    Cooke, David; MacDonald, A. Nicole; Hryciw, Aaron;

    2007-01-01

    The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described by a class......The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described...

  15. The origin of blue photoluminescence from nc-Si/SiO2 multilayers

    Institute of Scientific and Technical Information of China (English)

    Ma Zhong-Yuan; Xu Ling; Huang Xin-Fan; Chen Kun-Ji; Feng Duan; Guo Si-Hua; Chen De-Yuan; Wei De-Yuan; Yao Yao; Zhou Jiang; Huang Rui; Li Wei; Xu Jun

    2008-01-01

    Intensive blue photoluminescence (PL) was observed at room temperature from the nanocrystalline-Si/SiO2 (ncSi/SiO2) multilayers (MLs) obtained by thermal annealing of SiO/SiO2 MLs for the first time.By controlling the size of nc-Si formed in SiO sublayer from 3.5 to 1.5 nm,the PL peak blueshifts from 457 to 411 nm.Combining the analysis of TEM,Raman and absorption measurement,this paper attributes the blue PL to multiple luminescent centres at the interface of nc-Si and SiO2.

  16. The study of the change in the optical band-gap of titania nanoparticles supported on silica

    Directory of Open Access Journals (Sweden)

    SH Nasirian

    2013-09-01

    Full Text Available   In this letter, titania nanopowder and titania-silica nanocomposite were prepared using sol-gel method. Although the size of nanocrystallites and the mass fraction percent age of rutile phase ( after phase transformation were increased by increasing calcination in the two samples , their size in titania-silica nanocomposite was smaller than that in pure titania . Moreover, the calculations of the indirect optical band gap in the two samples show ed that by increasing temperature up to the transition onset point a nd above, the optical band gap had a steady growth and the corresponding wavelength reduced. However , a remarkable red shift in the indirect optical band gap was noticed in both samples around the transition onset point . The red shift was observed more in silica-titania nano composite than in titania nanopowder . In addition, the indirect band gap of silica-titania nano composite was less than that of pure titania in the same temperature conditions.

  17. Titania may produce abiotic oxygen atmospheres on habitable exoplanets

    CERN Document Server

    Narita, Norio; Masaoka, Shigeyuki; Kusakabe, Nobuhiko

    2015-01-01

    The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms. In this paper, we show that a previously unconsidered photochemical mechanism by titanium(IV) oxide (titania) can produce abiotic oxygen from liquid water under near ultraviolet (NUV) lights on the surface of exoplanets. Titania works as a photocatalyst to dissociate liquid water in this process. This mechanism offers a different source of a possibility of abiotic oxygen in atmospheres of exoplanets from previously considered photodissociation of water vapor in upper atmospheres by extreme ultraviolet (XUV) light. Our order-of-magnitude estimation shows that possible amounts of oxygen produced by this abiotic mechanism can be comparable with or even more than that in the atmosphere of the current ...

  18. Nanoengineering Titania for High Rate Lithium Storage: A Review

    Institute of Scientific and Technical Information of China (English)

    Chunhai Jiang; Jinsong Zhang

    2013-01-01

    Nanostructured titania have been intensively investigated as anode materials of Li-ion batteries for their excellent high rate performance.The size effects of TiO2 polymorphs (mainly rutile,anatase and TiO2-B) on their electrochemical performance and the latest efforts in nanoengineering titania anodes through enhancing their ionic or electronic transportation or both are reviewed in this work.We suppose that micron-or submicronsized porous structures assembled by TiO2 nanoparticles,nanowires/nanotubes or nanosheets with a high percentage of exposing high reactive facets together with a conductive percolating network are ideal anodes not only for high rate lithium storage but also for high packing densities of the active materials.

  19. Lithium ion batteries with titania/graphene anodes

    Science.gov (United States)

    Liu, Jun; Choi, Daiwon; Yang, Zhenguo; Wang, Donghai; Graff, Gordon L; Nie, Zimin; Viswanathan, Vilayanur V; Zhang, Jason; Xu, Wu; Kim, Jin Yong

    2013-05-28

    Lithium ion batteries having an anode comprising at least one graphene layer in electrical communication with titania to form a nanocomposite material, a cathode comprising a lithium olivine structure, and an electrolyte. The graphene layer has a carbon to oxygen ratio of between 15 to 1 and 500 to 1 and a surface area of between 400 and 2630 m.sup.2/g. The nanocomposite material has a specific capacity at least twice that of a titania material without graphene material at a charge/discharge rate greater than about 10 C. The olivine structure of the cathode of the lithium ion battery of the present invention is LiMPO.sub.4 where M is selected from the group consisting of Fe, Mn, Co, Ni and combinations thereof.

  20. Role of binder in the synthesis of titania membrane

    Indian Academy of Sciences (India)

    K S Seshadri; M Selvaraj; R Kesava Moorthy; K Varatharajan; M P Srinivasan; K B Lal

    2003-02-01

    The synthesis of titania membrane through sol–gel route involves hydrolysis of alkoxide, peptization of hydrous oxide of titanium to obtain a sol, adjustment of the sol viscosity by including a binder and filtration of the viscous sol through a microporous support, gelation and sintering to desired temperature. The binder plays an important role in that it not only helps in adjustment of sol viscosity but also helps in binding the sol particle with porous support. Here a comparative study on the role of different binders, viz. polyvinyl alcohol, polyethyleneimine, polyacrylamide, effect of their viscosity and surface tension effect on the morphology of the titania membrane is presented. The results show that among the three binders studied polyvinyl alcohol gave rise to membranes of desired characteristics when the sol viscosity was 0.08 pa.s.

  1. The formation of titania polymorphs under hydrothermal condition

    Institute of Scientific and Technical Information of China (English)

    ZHENG; Yanqing(郑燕青); SHI; Erwei(施尔畏); LI; Wenjun(李汶军); CHEN; Zhizhan(陈之战); ZHONG; Weizhuo(仲维卓); HU; Xingfang(胡行方)

    2002-01-01

    The formation process of crystal polymorphs of titania under hydrothermal condition is studied.According to the experimental results and theoretic analysis,the formation process of crystal polymorphs can be described as a unit process.It includes the formation of growth units,the formation of nuclei through the polymerization of growth unit,and the growth of crystallites.The influence of the environmental phase and growth conditions on the formation of polymorphs is reflected in the changes of the structures of growth units.For example,when changing the pH of the reaction medium,the structure of growth unit with the highest stable energy in the hydrothermal system changes.Then different titania polymorphs can be prepared.The absorption,movement,crystallization or desorption of the growth unit are related to crystalline structure.On the other hand,the formation of crystal inner defects is related to the disturbance of the crystallizing process.``

  2. Tin-Platinum catalysts interactions on titania and silica

    Energy Technology Data Exchange (ETDEWEB)

    Nava, N. [Instituto Mexicano del Petroleo Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico)], E-mail: tnava@imp.mx; Del Angel, P. [Instituto Mexicano del Petroleo Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico); Salmones, J. [Instituto Politecnico Nacional-ESIQIE UPALM, 07738 Mexico, D.F. (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, Brasil (Brazil); Santiago, P. [Instituto de Fisica, UNAM, Mexico, D. F., 04510 Mexico (Mexico)

    2007-09-30

    Pt-Sn was supported on titania and silica, and the resulting interactions between the components in prepared samples and the resulting interactions between the components before and after treatment with hydrogen were characterized by Moessbauer spectroscopy, X-ray diffraction, Rietveld refinement, high-resolution transmission electron microscopy (HRTEM) and catalytic tests data. Results show the presence of Pt and SnO{sub 2} after calcinations, and Pt{sub 3}Sn, PtSn and PtSn{sub 3} after reduction. Rietveld analysis shows that some Ti{sup 4+} are replaced by Sn{sup 4+} atoms in the titania structure. Finally, HRTEM and the practically absence of activity observed confirms that metallic platinum is encapsulated.

  3. Low-Temperature Reverse Microemulsion Synthesis, Characterization, and Photocatalytic Performance of Nanocrystalline Titanium Dioxide

    Directory of Open Access Journals (Sweden)

    Zhang Liu

    2012-01-01

    Full Text Available Nanocrystalline titanium dioxide (TiO2 was synthesized in microemulsions by using cetyltrimethylammonium bromide (CTAB as surfactant. In order to investigate the crystal transformation and photoactivity at low temperature, the as-prepared precipitates were aged at 65°C or calcined at various temperatures. Analyses using powder X-ray diffraction (XRD and Fourier transform infrared microscopy (FT-IR showed that precursors without aging or calcination were noncrystal and adsorbed by surfactant. After aging for 6 h, the amorphous TiO2 began to change into anatase. The obtained catalysts, which were synthesized in microemulsions with weight ratios of n-hexanol/CTAB/water as 6 : 3 : 1 and calcined at 500°C, presented the highest photocatalytic degradation rate on methyl orange (MO, while the catalysts, which were aged at 65°C for 90 h, also exhibited an outstanding photocatalytic performance and a little higher than that of the commercial titania photocatalyst Degussa P25.

  4. Solution equilibrium behind the room-temperature synthesis of nanocrystalline titanium dioxide.

    Science.gov (United States)

    Seisenbaeva, Gulaim A; Daniel, Geoffrey; Nedelec, Jean-Marie; Kessler, Vadim G

    2013-04-21

    Formation of nanocrystalline and monodisperse TiO2 from a water soluble and stable precursor, ammonium oxo-lactato-titanate, (NH4)8Ti4O4(Lactate)8·4H2O, often referred to as TiBALDH or TALH, is demonstrated to be due to a coordination equilibrium. This compound, individual in the solid state, exists in solution in equilibrium with ammonium tris-lactato-titanate, (NH4)2Ti(Lactate)3 and uniform crystalline TiO2 nanoparticles (anatase) stabilized by surface-capping with lactate ligands. This equilibrium can be shifted towards nano-TiO2via application of a less polar solvent like methanol or ethanol, dilution of the solution, introduction of salts or raising the temperature, and reverted on addition of polar and strongly solvating media such as dimethyl sulfoxide, according to NMR. Aggregation and precipitation of the particles were followed by DLS and could be achieved by a decrease in their surface charge by adsorption of strongly hydrogen-bonding cations, e.g. in solutions of ammonia, ethanolamine or amino acid arginine or by addition of ethanol. The observed equilibrium may be involved in formation of nano-titania on the surface of plant roots exerting chelating organic carboxylate ligands and thus potentially influencing plant interactions.

  5. EFFECTS OF SYNTHESIS PARAMETERS ON THE STRUCTURE OF TITANIA NANOTUBES

    Directory of Open Access Journals (Sweden)

    M. NORANI MUTI

    2008-08-01

    Full Text Available Detection of hydrogen is crucial for industrial process control and medical applications where presence of hydrogen in breath indicates different type of health problems particularly in infants. A better performed sensor with high sensitivity, selectivity, reliability and faster response time would be critical and sought after especially for medical applications. Titanium dioxide nanotube structure is chosen as an active component in the gas sensor because of its highly sensitive electrical resistance to hydrogen over a wide range of concentrations. The objective of the work is to investigate the effect of the anodizing conditions on the structure of titania nanotubes produced by anodizing method. The anodizing parameters namely the ambient temperature and separation of electrodes are varied accordingly to find the optimum anodizing conditions for production of good quality titania nanotubes for enhanced properties based on their uniformity, coverage, pore size and crystallinity. Samples of nanotubes produced were subjected to annealing process at varying time and temperature in order to improve the crystallinity of the nanotubes. The highly ordered porous titania nanotubes produced by this method are of tabular shape and have good uniformity and alignment over large areas. The pore size of the titania nanotubes ranges from 47 to 94 nm, while the wall thickness is in the range of 17 to 26 nm. The length of the nanotubes was found to be about 280 nm. The structure of nanotubes changes from amorphous to crystalline after undergoing annealing treatment. Nanotubes have also shown to have better crystallinity if they were subjected to annealing treatment at higher temperature. The characteristics of nanotubes obtained are found to be agreeable to those that have been reported to show improved hydrogen gas sensing properties.

  6. Titania may produce abiotic oxygen atmospheres on habitable exoplanets

    Science.gov (United States)

    Narita, Norio; Enomoto, Takafumi; Masaoka, Shigeyuki; Kusakabe, Nobuhiko

    2015-12-01

    The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms. In this paper, we show that a previously unconsidered photochemical mechanism by titanium (IV) oxide (titania) can produce abiotic oxygen from liquid water under near ultraviolet (NUV) lights on the surface of exoplanets. Titania works as a photocatalyst to dissociate liquid water in this process. This mechanism offers a different source of a possibility of abiotic oxygen in atmospheres of exoplanets from previously considered photodissociation of water vapor in upper atmospheres by extreme ultraviolet (XUV) light. Our order-of-magnitude estimation shows that possible amounts of oxygen produced by this abiotic mechanism can be comparable with or even more than that in the atmosphere of the current Earth, depending on the amount of active surface area for this mechanism. We conclude that titania may act as a potential source of false signs of life on habitable exoplanets.Reference:Narita N. et al.,Scientific Reports 5, Article number: 13977 (2015)http://www.nature.com/articles/srep13977

  7. Fabrication and structural characterization of highly ordered titania nanotube arrays

    Science.gov (United States)

    Shi, Hongtao; Ordonez, Rosita

    Titanium (Ti) dioxide nanotubes have drawn much attention in the past decade due to the fact that titania is an extremely versatile material with a variety of technological applications. Anodizing Ti in different electrolytes has proved to be quite successful so far in creating the nanotubes, however, their degree of order is still not nearly as good as nanoporous anodic alumina. In this work, we first deposit a thin layer of aluminum (Al) onto electropolished Ti substrates, using thermal evaporation. Such an Al layer is then anodized in 0.3 M oxalic acid, forming an ordered nanoporous alumina mask on top of Ti. Afterwards, the anodization of Ti is accomplished at 20 V in solutions containing 1 M NaH2PO4 and 0.5% HF or H2SO4, which results in the creation of ordered titania nanotube arrays. The inner pore diameter of the nanotubes can be tuned from ~50 nm to ~75 nm, depending on the anodization voltage applied to Al or Ti. X-ray diffractometry shows the as-grown titania nanotubes are amorphous. Samples annealed at different temperatures in ambient atmosphere will be also reported.

  8. Titania may produce abiotic oxygen atmospheres on habitable exoplanets.

    Science.gov (United States)

    Narita, Norio; Enomoto, Takafumi; Masaoka, Shigeyuki; Kusakabe, Nobuhiko

    2015-09-10

    The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms. In this paper, we show that a previously unconsidered photochemical mechanism by titanium (IV) oxide (titania) can produce abiotic oxygen from liquid water under near ultraviolet (NUV) lights on the surface of exoplanets. Titania works as a photocatalyst to dissociate liquid water in this process. This mechanism offers a different source of a possibility of abiotic oxygen in atmospheres of exoplanets from previously considered photodissociation of water vapor in upper atmospheres by extreme ultraviolet (XUV) light. Our order-of-magnitude estimation shows that possible amounts of oxygen produced by this abiotic mechanism can be comparable with or even more than that in the atmosphere of the current Earth, depending on the amount of active surface area for this mechanism. We conclude that titania may act as a potential source of false signs of life on habitable exoplanets.

  9. Microstructural characterization of the V-doped nano-titania

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Patra, A.K.; Sastry, P.U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tyagi, A.K., E-mail: aktyagi@barc.gov.i [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2009-08-12

    A new modified sol-gel method has been developed to synthesize undoped nano-titania and vanadium-doped nano-titania. XRD data and the Raman spectra indicate that even after 10 mol% doping of vanadium in the crystal lattice sites of TiO{sub 2}, the samples are phase pure with the anatase structure. The average particle size of these materials is about 11.5 nm, as calculated from the XRD peak broadening and TEM. Small angle X-ray scattering (SAXS) was also used for the determination of the particle size of these vanadium-doped titania samples. The SAXS parameters were determined assuming near spherical particle shape. The SAXS results were in agreement with the particle size as obtained by TEM. A negligible variation in the particle size was observed as a function of doping percentage upto a limiting value of 5 mol% doping of vanadium in the TiO{sub 2} lattice. The results of the SAXS are in good agreement with the XRD and the TEM results.

  10. Activity of titania and zeolite samples dosed with triethylamine

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Caitlin; Gole, James L.; Brauer, Jonathann I.; Graham, Samuel; Hu, Jian Z.; Kenvin, Jeff; D' Amico, Andrew D.; White, Mark

    2016-01-15

    Certain properties of titania and the ammonium- and proton-form of Y zeolites (silica/alumina ratio of 5.2) were explored before and after treatment by triethylamine (TEA). The effect of the triethylamine upon the physical and chemical properties of both titania and the zeolite were characterized by physical and chemical adsorption methods. BET surface area data showed enhanced surface area of the TEA-treated nanotitania over the untreated nanotitania whereas the TEA-treated zeolite showed a considerable decrease in surface area compared to the untreated zeolite. TPD of the TEA-treated Y zeolite showed that weakly adsorbed TEA left the surface between 150 and 300 oC; strongly adsorbed TEA decomposed to ethylene and ammonia at higher temperatures. XPS, IR, and Raman spectroscopies, powder XRD, and 27Al MAS-NMR spectroscopy were used to further characterize the changes introduced by in-situ nitridation. Pre-adsorbed triethylamine decorated acid sites so as to neutralize these sites for the reaction of methanol to dimethylether. Carbon monoxide and ormaldehyde, products of the methanol probe reaction, were observed-- suggesting that basic sites are present in this treated zeolite and titania.

  11. Preparation of doping titania antibacterial powder by ultrasonic spray pyrolysis

    Institute of Scientific and Technical Information of China (English)

    WEI Shun-wen; PENG Bing; CHAI Li-yuan; LIU Yun-chao; LI Zhu-ying

    2008-01-01

    Doping titania powders were synthesized by ultrasonic spray pyrolysis method from an aqueous solution containing H2TiF6 and AgNO3. The effects of the processing parameters on panicle size distribution, structure, and morphology of doping panicles were investigated. The results show that aggregation-free spherical panicles with average diameter of 200-600 nm are obtained and the particle size of the powder can be controlled by adjusting the concentration of solution. The experimental approach indicates that the size and the value of standard deviation of panicle size increase from 210 nm to 450 nm and from 0.46 to 0.73 respectively with the increase of the titanic ion concentration from 0.05 to 0.4 mol/L. Composite TiOF2 is obtained when the pyrolysis temperature is set to be 400 ℃. With increasing pyrolysis temperature from 400 ℃ to 800 ℃, the crystal size of titania powders increases from 14.1 to 26.5 nm and TiOF2 content of powder decreases dramatically. The property of ion released from powder is affected significantly by the pyrolysis temperature, and the amount of fluorine ion and silver ion released from powder decrease with increasing pyrolysis temperature. The optical property of doping titania powders is not affected by pyrolysis temperature. Antibacterial test results show that composite powders containing more fluorine ions exhibit stronger antibacterial activity against E.coli.

  12. Optoelectronic Properties of Hybrid Titania Nanotubes/Hematite Nanoparticles Structures

    Science.gov (United States)

    Wang, Lili; Panaitescu, Eugen; Menon, Latika

    2015-03-01

    TiO2/Fe2O3 nanostructures are becoming promising alternatives for improving cost effectiveness (in /W) of emerging photovoltaic devices such as dye sensitized or metal-insulator-semiconductor solar cells, combining the low cost, earth abundance and stability of the materials with the enhanced performance offered by the nanoscale architecture. We investigated novel, high quality titania/hematite composites, namely hematite nanoparticle decorated titania nanotube arrays, which were obtained by a simple, inexpensive and easily scalable two-step process, electrochemical anodization of titanium followed by forced hydrolysis. The titania nanotubular scaffold provides a large active surface area, while the iron oxide nanoparticles significantly broaden the light absorption range into the visible region. The morphological and structural characteristics of the samples were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The light absorption efficiency was measured by diffuse reflectance spectroscopy (DRS), and the optoelectronic behavior of the hybrid structures was analyzed by IV measurements under simulated solar illumination. The influence of the synthesis process and the structure design on the photovoltaic performance is currently investigated for optimal device prototyping.

  13. Preparation and properties of DLC/MoS2 multilayer coatings for high humidity tribology

    Science.gov (United States)

    Zhao, Xiaoyu; Lu, Zhibin; Wu, Guizhi; Zhang, Guangan; Wang, Liping; Xue, Qunji

    2016-06-01

    The DLC/MoS2 multilayer coatings with different modulus ratios were deposited by magnetron sputtering in this study. The morphology, structure, composition, mechanical properties and tribological properties were investigated using several analytical techniques (FESEM, AFM, TEM, AES, XPS, nanoindentation and high humidity tribological test). The results showed that the well-defined multilayer coatings were composed of densely packed particles in which many nanocrystallines with some kinds of defects were distributed in matrix. The incorporation of oxygen into the lattice led to the degraded chemical stability. The coating’s hardness and elastic modulus were almost in the same range. Moderate improvement on the high humidity tribological properties were obtained, which was important for the extension of the service life of MoS2 in humid air.

  14. Multiphase Nanocrystalline Ceramic Concept for Nuclear Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Mecartnery, Martha [Univ. of California, Irvine, CA (United States); Graeve, Olivia [Univ. of California, San Diego, CA (United States); Patel, Maulik [Univ. of Liverpool (United Kingdom)

    2017-05-25

    The goal of this research is to help develop new fuels for higher efficiency, longer lifetimes (higher burn-up) and increased accident tolerance in future nuclear reactors. Multiphase nanocrystalline ceramics will be used in the design of simulated advanced inert matrix nuclear fuel to provide for enhanced plasticity, better radiation tolerance, and improved thermal conductivity

  15. Double-metal-gate nanocrystalline Si thin film transistors with flexible threshold voltage controllability

    Energy Technology Data Exchange (ETDEWEB)

    Chiou, Uio-Pu; Pan, Fu-Ming, E-mail: fmpan@faculty.nctu.edu.tw [Department of Materials Science and Engineering, National Chiao-Tung University, Hsinchu 30050, Taiwan (China); Shieh, Jia-Min, E-mail: jmshieh@narlabs.org.tw, E-mail: jmshieh@faculty.nctu.edu.tw [National Nano Device Laboratories, No. 26, Prosperity Road 1, Hsinchu 30078, Taiwan (China); Departments of Photonics and Institute of Electro-Optical Engineering, National Chiao-Tung University, Hsinchu 30010, Taiwan (China); Yang, Chih-Chao [National Nano Device Laboratories, No. 26, Prosperity Road 1, Hsinchu 30078, Taiwan (China); Huang, Wen-Hsien [Department of Materials Science and Engineering, National Chiao-Tung University, Hsinchu 30050, Taiwan (China); National Nano Device Laboratories, No. 26, Prosperity Road 1, Hsinchu 30078, Taiwan (China); Kao, Yo-Tsung [Departments of Photonics and Institute of Electro-Optical Engineering, National Chiao-Tung University, Hsinchu 30010, Taiwan (China)

    2013-11-11

    We fabricated nano-crystalline Si (nc-Si:H) thin-film transistors (TFTs) with a double-metal-gate structure, which showed a high electron-mobility (μ{sub FE}) and adjustable threshold voltages (V{sub th}). The nc-Si:H channel and source/drain (S/D) of the multilayered TFT were deposited at 375 °C by inductively coupled plasma chemical vapor deposition. The low grain-boundary defect density of the channel layer is responsible for the high μ{sub FE} of 370 cm{sup 2}/V-s, a steep subthreshold slope of 90 mV/decade, and a low V{sub th} of −0.64 V. When biased with the double-gate driving mode, the device shows a tunable V{sub th} value extending from −1 V up to 2.7 V.

  16. Passivation of nanocrystalline TiO2 junctions by surface adsorbed phosphinate amphiphiles enhances the photovoltaic performance of dye sensitized solar cells

    KAUST Repository

    Wang, Mingkui

    2009-01-01

    We report a new class of molecular insulators that electronically passivate the surface of nanocrystalline titania films for high performance dye sensitized solar cells (DSC). Using electrical impedance measurements we demonstrate that co-adsorption of dineohexyl bis-(3,3-dimethyl-butyl)-phosphinic acid (DINHOP), along with the amphiphilic ruthenium sensitizer Z907Na increased substantially the power output of the cells mainly due to a retardation of interfacial recombination of photo-generated charge carriers. The use of phosphinates as anchoring groups opens up new avenues for modification of the surface by molecular insulators, sensitizers and other electro-active molecules to realize the desired optoelectronic performance of devices based on oxide junctions. © 2009 The Royal Society of Chemistry.

  17. Multilayer graphene waveguides

    CERN Document Server

    Smirnova, Daria; Shadrivov, Ilya; Kivshar, Yuri

    2014-01-01

    We study dispersion properties of TM-polarized electromagnetic waves guided by a multilayer graphene metamaterial. We demonstrate that both dispersion and localization of the guided modes can be efficiently controlled by changing the number of layers in the structure. Remarkably, we find that in the long wavelength limit, the dispersion of the fundamental mode of the N-layer graphene structure coincides with the dispersion of a plasmon mode supported by a single graphene layer, but with N times larger conductivity. We also compare our exact dispersion relations with the results provided by the effective media model.

  18. Process for manufacturing multilayer capacitors

    Science.gov (United States)

    Lauf, Robert J.; Holcombe, Cressie E.; Dykes, Norman L.

    1996-01-01

    The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation.

  19. Titania-alumina aerogel materials for degradation of rhodamine B dye: Impact of particle size of titania

    Science.gov (United States)

    Shrestha, Sunav

    Disposal of pollutants, mainly organic dyes from textile industries are the primary sources of water pollution in developing countries, and often leading to scarcity of clean water. These dyes can undergo further oxidation and form several toxic compounds, which possess threat to the water ecosystem. It is therefore necessary to remove these organics from effluents for a clean environment. Among the various methods, Advanced Oxidation Processes (AOPs) called heterogeneous photocatalysis is considered as an effective method for the removal of organics from water sources. In this regard, a set of titania-alumina (TiO2-Al2O3) mixed oxide materials were prepared by supercritical drying method and investigated towards the degradation of a model pollutant, rhodamine B (RhB). The physico-chemical properties of the synthesized materials were studied in detail using several techniques that include powder X-ray diffraction, nitrogen physisorption, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy (XPS). The Electrospray ionization-Mass spectroscopic (ESI-MS) studies were also carried out to confirm the degradation of the RhB by identifying its intermediate products. The results indicate that the particle size of the photoactive species, titania, was the key factor for effective photocatalytic degradation of the RhB dye over the titania-alumina mixed oxide materials.

  20. Magnetic metallic multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Hood, R.Q.

    1994-04-01

    Utilizing self-consistent Hartree-Fock calculations, several aspects of multilayers and interfaces are explored: enhancement and reduction of the local magnetic moments, magnetic coupling at the interfaces, magnetic arrangements within each film and among non-neighboring films, global symmetry of the systems, frustration, orientation of the various moments with respect to an outside applied field, and magnetic-field induced transitions. Magnetoresistance of ferromagnetic-normal-metal multilayers is found by solving the Boltzmann equation. Results explain the giant negative magnetoresistance encountered in these systems when an initial antiparallel arrangement is changed into a parallel configuration by an external magnetic field. The calculation depends on (1) geometric parameters (thicknesses of layers), (2) intrinsic metal parameters (number of conduction electrons, magnetization, and effective masses in layers), (3) bulk sample properties (conductivity relaxation times), (4) interface scattering properties (diffuse scattering versus potential scattering at the interfaces, and (5) outer surface scattering properties (specular versus diffuse surface scattering). It is found that a large negative magnetoresistance requires considerable asymmetry in interface scattering for the two spin orientations. Features of the interfaces that may produce an asymmetrical spin-dependent scattering are studied: varying interfacial geometric random roughness with no lateral coherence, correlated (quasi-periodic) roughness, and varying chemical composition of the interfaces. The interplay between these aspects of the interfaces may enhance or suppress the magnetoresistance, depending on whether it increases or decreases the asymmetry in the spin-dependent scattering of the conduction electrons.

  1. Ultrahard Multilayer Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chrzan, D.C.; Dugger, M.; Follstaedt, D.M.; Friedman, Lawrence H.; Friedmann, T.A.; Knapp, J.A.; McCarty, K.F.; Medlin, D.L.; Mirkarimi, P.B.; Missert, N.; Newcomer, P.P.; Sullivan, J.P.; Tallant, D.R.

    1999-05-01

    We have developed a new multilayer a-tC material that is thick stress-free, adherent, low friction, and with hardness and stiffness near that of diamond. The new a-tC material is deposited by J pulsed-laser deposition (PLD) at room temperature, and fully stress-relieved by a short thermal anneal at 600°C. A thick multilayer is built up by repeated deposition and annealing steps. We measured 88 GPa hardness, 1100 GPa Young's modulus, and 0.1 friction coefficient (under high load). Significantly, these results are all well within the range reported for crystalline diamond. In fact, this material, if considered separate from crystalline diamond, is the 2nd hardest material known to man. Stress-free a-tC also has important advantages over thin film diamond; namely, it is smooth, processed at lower temperature, and can be grown on a much broader range of substrates. This breakthrough will enable a host of applications that we are actively pursuing in MEMs, sensors, LIGA, etc.

  2. Magneto-optical multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bader, S.D.

    1992-02-01

    Magneto-optical multilayers are of interest to the optical data storage community as a possible second-generation medium of the future. The important Co/Pt-superlattice system is introduced in this respect, and an extensive reference listing is provided to previous research. Magneto-optical modeling studies of Co/Pt are presented, and it is concluded that the interfacial Pt is magnetized and is magneto-optically active at the short wavelengths of interest ({approximately}4 eV) for applications. Magneto-optics in the ultrathin limit are discussed, and an additivity law is presented and verified experimentally utilizing data for epitaxial Fe/Ag(111) superlattices. Finally, the surface magnetic anisotropy that provides the vertical easy axes of magnetization in candidate superlattice systems is discussed and illustrated experimentally using ultrathin epitaxial films of Fe grown on a variety of substrates. It is concluded that magneto-optic multilayers will provide many stimulating basic and applied challenges in the years ahead.

  3. Evaluation of the Morphology and Osteogenic Potential of Titania-Based Electrospun Nanofibers

    Directory of Open Access Journals (Sweden)

    Xiaokun Wang

    2012-01-01

    Full Text Available Submicron-scale titania-based ceramic fibers with various compositions have been prepared by electrospinning. The as-prepared nanofibers were heat-treated at 700°C for 3 h to obtain pure inorganic fiber meshes. The results show that the diameter and morphology of the nanofibers are affected by starting polymer concentration and sol-gel composition. The titania and titania-silica nanofibers had the average diameter about 100–300 nm. The crystal phase varied from high-crystallized rutile-anatase mixed crystal to low-crystallized anatase with adding the silica addition. The morphology and crystal phase were evaluated by SEM and XRD. Bone-marrow-derived mesenchymal stem cells were seeded on titania-silica 50/50 fiber meshes. Cell number and early differentiation marker expressions were analyzed, and the results indicated osteogenic potential of the titania-silica 50/50 fiber meshes.

  4. Synthesis of Anatase Titania Nanostructures at Room Temperature by PECVD Technique

    Institute of Scientific and Technical Information of China (English)

    K.M.K. Srivatsa; Deepak Chhikara; M. Senthil Kumar

    2011-01-01

    titania nanostructures have been synthesized at room temperature by plasma enhanced chemical vapor deposition (PECVD) process on silicon (100) substrates using titanium tetraisopropoxide [Ti(OC3H7)4, TTIP] vapor, argon and oxygen mixtures under various deposition pressures. The deposited titania has been characterized for its structural, morphological and chemical composition by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray (EDX) spectroscopy and Fourier transform infrared (FTIR) spectroscopy recordings. With the variation of deposition pressure, titania assumes various nanostructures viz. nanocrystals, nanoparticles, noanorods and comb-like structure. EDX and FTIR measurements show that the deposited titania is of high chemical purity. The possible growth mechanisms for the observed titania nanostructures have been discussed.

  5. Microwave-assisted additive free synthesis of nanocrystalline zinc oxide

    OpenAIRE

    Bhatte, Kushal D.; Tambade, Pawan; Fujita, Shin-ichiro; Arai, Masahiko; Bhalchandra M. Bhanage

    2010-01-01

    An additive free synthesis of nanocrystalline zinc oxide using microwave technique is reported. Current methodology is faster, cleaner and cost effective compared with conventional method for the synthesis of zinc oxide nanocrystalline materials. The structure and morphology of nanocrystalline zinc oxide was investigated by TEM, XRD, EDAX, UV-Vis spectroscopy. The results demonstrate that microwave heating can produce polygonal zinc oxide within a short span of time.

  6. Structural and magnetic properties of bulk nanocrystalline Erbium metal

    Directory of Open Access Journals (Sweden)

    Ming Yue

    2011-06-01

    Full Text Available Bulk nanocrystalline Erbium metals were prepared via Spark Plasma Sintering (SPS and subsequent annealing process. The nanocrystalline Er metals have the same hexagonal close packed structure as that of coarse-grained sample. Decrease in grain size results in remarkable changes in the three magnetic ordering temperatures of the nanocrystalline Er metal. At 5 K, the magnetization drops by 10.9%, while the coercivity increases by 4 times for nanocrystalline Er compared with those of coarse-grained sample. These results indicate the remarkable influence of the nanostructure on the magnetism of Er due to finite size effect.

  7. Deformation sensor based on polymer-supported discontinuous graphene multi-layer coatings

    Energy Technology Data Exchange (ETDEWEB)

    Carotenuto, G.; Schiavo, L.; Romeo, V.; Nicolais, L. [Institute for Composite and Biomedical Materials, National Research Council, Piazzale E. Fermi, 1, 80055 Portici (Italy)

    2014-05-15

    Graphene can be conveniently used in the modification of polymer surfaces. Graphene macromolecules are perfectly transparent to the visible light and electrically conductive, consequently these two properties can be simultaneously provided to polymeric substrates by surface coating with thin graphene layers. In addition, such coating process provides the substrates of: water-repellence, higher surface hardness, low-friction, self-lubrication, gas-barrier properties, and many other functionalities. Polyolefins have a non-polar nature and therefore graphene strongly sticks on their surface. Nano-crystalline graphite can be used as graphene precursor in some chemical processes (e.g., graphite oxide synthesis by the Hummer method), in addition it can be directly applied to the surface of a polyolefin substrate (e.g., polyethylene) to cover it by a thin graphene multilayer. In particular, the nano-crystalline graphite perfectly exfoliate under the application of a combination of shear and friction forces and the produced graphene single-layers perfectly spread and adhere on the polyethylene substrate surface. Such polymeric materials can be used as ITO (indium-tin oxide) substitute and in the fabrication of different electronic devices. Here the fabrication of transparent resistive deformation sensors based on low-density polyethylene films coated by graphene multilayers is described. Such devices are very sensible and show a high reversible and reproducible behavior.

  8. Deformation sensor based on polymer-supported discontinuous graphene multi-layer coatings

    Science.gov (United States)

    Carotenuto, G.; Schiavo, L.; Romeo, V.; Nicolais, L.

    2014-05-01

    Graphene can be conveniently used in the modification of polymer surfaces. Graphene macromolecules are perfectly transparent to the visible light and electrically conductive, consequently these two properties can be simultaneously provided to polymeric substrates by surface coating with thin graphene layers. In addition, such coating process provides the substrates of: water-repellence, higher surface hardness, low-friction, self-lubrication, gas-barrier properties, and many other functionalities. Polyolefins have a non-polar nature and therefore graphene strongly sticks on their surface. Nano-crystalline graphite can be used as graphene precursor in some chemical processes (e.g., graphite oxide synthesis by the Hummer method), in addition it can be directly applied to the surface of a polyolefin substrate (e.g., polyethylene) to cover it by a thin graphene multilayer. In particular, the nano-crystalline graphite perfectly exfoliate under the application of a combination of shear and friction forces and the produced graphene single-layers perfectly spread and adhere on the polyethylene substrate surface. Such polymeric materials can be used as ITO (indium-tin oxide) substitute and in the fabrication of different electronic devices. Here the fabrication of transparent resistive deformation sensors based on low-density polyethylene films coated by graphene multilayers is described. Such devices are very sensible and show a high reversible and reproducible behavior.

  9. Methods of making non-covalently bonded carbon-titania nanocomposite thin films and applications of the same

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Yu Teng; Vijayan, Baiju K.; Gray, Kimberly A.; Hersam, Mark C.

    2016-07-19

    In one aspect, a method of making non-covalently bonded carbon-titania nanocomposite thin films includes: forming a carbon-based ink; forming a titania (TiO.sub.2) solution; blade-coating a mechanical mixture of the carbon-based ink and the titania solution onto a substrate; and annealing the blade-coated substrate at a first temperature for a first period of time to obtain the carbon-based titania nanocomposite thin films. In certain embodiments, the carbon-based titania nanocomposite thin films may include solvent-exfoliated graphene titania (SEG-TiO.sub.2) nanocomposite thin films, or single walled carbon nanotube titania (SWCNT-TiO.sub.2) nanocomposite thin films.

  10. Multi-layers castings

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2010-01-01

    Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

  11. Multilayer Multidimensional Extension Set Theory

    Institute of Scientific and Technical Information of China (English)

    CAO Shao-zhong; YANG Guo-wei; TU Xu-yan

    2006-01-01

    In order to study the contradiction problem of multilayer multidimensional complex systems, the concepts of extension field and stable field of intersection and union of multilayer multidimensional extension set are given. Then the related operations and properties are discussed. The results of study expand the concepts of intersection and union of extension set to a general situation, and provide the theoretical basis for production of the concepts of intersection and union of multilayer multidimensional matter element system extension set. In this way, it will be possible that matter element system theory is used to creative designs of complex systems.

  12. Microemulsion-based synthesis of nanocrystalline materials.

    Science.gov (United States)

    Ganguli, Ashok K; Ganguly, Aparna; Vaidya, Sonalika

    2010-02-01

    Microemulsion-based synthesis is found to be a versatile route to synthesize a variety of nanomaterials. The manipulation of various components involved in the formation of a microemulsion enables one to synthesize nanomaterials with varied size and shape. In this tutorial review several aspects of microemulsion based synthesis of nanocrystalline materials have been discussed which would be of interest to a cross-section of researchers working on colloids, physical chemistry, nanoscience and materials chemistry. The review focuses on the recent developments in the above area with current understanding on the various factors that control the structure and dynamics of microemulsions which can be effectively used to manipulate the size and shape of nanocrystalline materials.

  13. Structurally stabilized organosilane-templated thermostable mesoporous titania.

    Science.gov (United States)

    Amoli, Vipin; Tiwari, Rashmi; Dutta, Arghya; Bhaumik, Asim; Sinha, Anil Kumar

    2014-01-13

    Structurally thermostable mesoporous anatase TiO2 (m-TiO2) nanoparticles, uniquely decorated with atomically dispersed SiO2, is reported for the first time. The inorganic Si portion of the novel organosilane template, used as a mesopores-directing agent, is found to be incorporated in the pore walls of the titania aggregates, mainly as isolated sites. This is evident by transmission electron microscopy and high-angle annular dark field scanning transmission electron microscopy, combined with electron dispersive X-ray spectroscopy. This type of unique structure provides exceptional stability to this new material against thermal collapse of the mesoporous structure, which is reflected in its high surface area (the highest known for anatase titania), even after high-temperature (550 °C) calcination. Control of crystallite size, pore diameter, and surface area is achieved by varying the molar ratios of the titanium precursor and the template during synthesis. These mesoporous materials retain their porosity and high surface area after template removal and further NaOH/HCl treatment to remove silica. We investigate their performance for dye-sensitized solar cells (DSSCs) with bilayer TiO2 electrodes, which are prepared by applying a coating of m-TiO2 onto a commercial titania (P25) film. The high surface area of the upper mesoporous layer in the P25-m-TiO2 DSSC significantly increases the dye loading ability of the photoanode. The photocurrent and fill factor for the DSSC with the bilayer TiO2 electrode are greatly improved. The large increase in photocurrent current (ca. 56%) in the P25-m-TiO2 DSSC is believed to play a significant role in achieving a remarkable increase in the photovoltaic efficiency (60%) of the device, compared to DSSCs with a monolayer of P25 as the electrode. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. New Nanocrystalline Materials for Power Electronics Applications

    Directory of Open Access Journals (Sweden)

    Jan Bydzovsky

    2008-01-01

    Full Text Available New nanocrystalline materials for the applications in the power electronics systems are developed and tested.These materials are intended to be used in the magnetic circuits of switching-mode power supplies (SMPS. The aim was toachieve extremely low hysteresis and non-linearity in operating region resulting in increased efficiency and decreased weightand size whilst keeping low price of the high-power frequency converters for SMPS.

  15. New Nanocrystalline Materials for Power Electronics Applications

    OpenAIRE

    Jan Bydzovsky; Jozef Kuchta; Elemir Usak; Peter Svec

    2008-01-01

    New nanocrystalline materials for the applications in the power electronics systems are developed and tested. These materials are intended to be used in the magnetic circuits of switching-mode power supplies (SMPS). The aim was to achieve extremely low hysteresis and non-linearity in operating region resulting in increased efficiency and decreased weight and size whilst keeping low price of the high-power frequency converters for SMPS.

  16. Quantized Nanocrystalline CdTe Thin Films

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nanocrystalline CdTe thin films were prepared by asymmetric rectangular pulse electrodeposition in organic solution at 110°C. STM image shows a porous network morphology constructed by interconnected spherical CdTe crystallites with a mean diameter of 4.2 nm. A pronounced size quantization was indicated in the action and absorption spectra. Potentials dependence dual conductive behavior was revealed in the photocurrent-potential (I-V) curves.

  17. Simple Preparation of the Photocatalyst of Sn2+-doped Titania

    Institute of Scientific and Technical Information of China (English)

    Dao Rong LI; Ling Na SUN; Chang Wen HU

    2006-01-01

    Preparation method of photocatalyst, using TiCl4 and SnCl2 as raw material and photocatalytic activity of nano-scaled core-shell Sn2+-doped titania photocatalyst was studied in this paper. The as-prepared samples were studied by UV-Vis, XRD, XPS, TEM. The particles of Sn2+-doped TiO2 photocatalyst, calcined from 150 to 600 ℃ for 5 h, possesses narrow particle size distribution and the sample was composed of anatase phase. Its photocatalytic efficiency was investigated by UV irradiation.

  18. PREPARATION AND CHARACTERIZATION OF BAMBOO NANOCRYSTALLINE CELLULOSE

    Directory of Open Access Journals (Sweden)

    Mengjiao Yu,

    2012-02-01

    Full Text Available Nanocrystalline cellulose (NCC has many potential applications because of its special properties. In this paper, NCC was prepared from bamboo pulp. Bamboo pulp was first pretreated with sodium hydroxide, followed by hydrolysis with sulfuric acid. The concentration of sulfuric acid and the hydrolysis time on the yield of NCC were studied. The results showed that sulfuric acid concentration had larger influence than the hydrolysis time on the yield of NCC. When the temperature was 50oC, the concentration of sulfuric acid was 48wt% and the reaction time was 30 minutes, a high quality of nanocrystalline cellulose was obtained; under these conditions, the length of the nanocrystalline cellulose ranged from 200 nm to 500 nm, the diameter was less than 20 nm, the yield was 15.67wt%, and the crystallinity was 71.98%, which is not only higher than those of cellulose nanocrystals prepared from some non-wood materials, but also higher than bamboo cellulose nanocrystals prepared by other methods.

  19. Preparation and Instability of Nanocrystalline Cuprous Nitride.

    Science.gov (United States)

    Reichert, Malinda D; White, Miles A; Thompson, Michelle J; Miller, Gordon J; Vela, Javier

    2015-07-06

    Low-dimensional cuprous nitride (Cu3N) was synthesized by nitridation (ammonolysis) of cuprous oxide (Cu2O) nanocrystals using either ammonia (NH3) or urea (H2NCONH2) as the nitrogen source. The resulting nanocrystalline Cu3N spontaneously decomposes to nanocrystalline CuO in the presence of both water and oxygen from air at room temperature. Ammonia was produced in 60% chemical yield during Cu3N decomposition, as measured using the colorimetric indophenol method. Because Cu3N decomposition requires H2O and produces substoichiometric amounts of NH3, we conclude that this reaction proceeds through a complex stoichiometry that involves the concomitant release of both N2 and NH3. This is a thermodynamically unfavorable outcome, strongly indicating that H2O (and thus NH3 production) facilitate the kinetics of the reaction by lowering the energy barrier for Cu3N decomposition. The three different Cu2O, Cu3N, and CuO nanocrystalline phases were characterized by a combination of optical absorption, powder X-ray diffraction, transmission electron microscopy, and electronic density of states obtained from electronic structure calculations on the bulk solids. The relative ease of interconversion between these interesting and inexpensive materials bears possible implications for catalytic and optoelectronic applications.

  20. Multilayer Membranes Based on Ceramic Materials—Sol-gel Synthesis, Characterization and Membrane Performance

    Institute of Scientific and Technical Information of China (English)

    Sun Qianyao; Xu Chunming

    2007-01-01

    In nearly all chemical and petrochemical systems, separation of products generally accounts for more than 50% of the capital cost and the greatest part of the energy consumption. It is generally believed that membrane systems can offer benefits in both reducing the energy consumption of the separation stages and lowering the capital expenditure (CAPEX). Microporous ceramic membranes have the potential to overcome the limitation in polymer membranes operation, which has been the subject of a large amount of research worldwide in the last two decades. And most of the research has aimed at the production of the asymmetric multilayered membrane based on amorphous oxides by sol-gel techniques. The paper is to give an overview of publications on ceramic membranes, including less common materials of titania, zirconia, which can be used for pervaporation in corrosive media. Commercially available microporous membranes based on these membrane materials and the membrane economics are also summarized.

  1. Elucidating How Surface Functionalization of Multiwalled Carbon Nanotube Affects Nanostructured MWCNT/Titania Hybrid Materials

    Directory of Open Access Journals (Sweden)

    Cheng-Fu Yang

    2015-01-01

    Full Text Available The new class of multiwalled carbon nanotube (MWCNT/titania nanocomposites was prepared using a sol-gel technique. The addition of titania to MWCNTs has the potential to provide new capability for the development of electrical devices by taking advantage of the favorable electric characteristics of MWCNTs. MWCNTs were first functionalized with carboxyl, acyl chloride, amine, and hydroxyl groups and were then dispersed in a tetraisopropyl titanate (TIPT solution via ultrasonic processing. After gelation, well-dispersed titania in the MWCNT/titania nanocomposites was obtained. Functionalized MWCNTs with varied functional groups were proved by Fourier transform infrared spectroscopy (FT-IR. For the nanocomposites, the degree of the sol-gel process were proved by Raman spectroscopy and wide-angle X-ray diffraction (WAXD. Furthermore, the morphology of the MWCNT/titania nanocomposites was observed using transmission electron microscopy (TEM. In the sol-gel process, the functionalized MWCNTs with carboxyl, acyl chloride, amine, and hydroxyl groups have resulted in the carbon nanotube-graft-titania nanocomposites with a network structure of titania between the carbon nanotubes.

  2. Recent progress in mesoporous titania materials: adjusting morphology for innovative applications

    Directory of Open Access Journals (Sweden)

    Juan L Vivero-Escoto, Ya-Dong Chiang, Kevin C-W Wu and Yusuke Yamauchi

    2012-01-01

    Full Text Available This review article summarizes recent developments in mesoporous titania materials, particularly in the fields of morphology control and applications. We first briefly introduce the history of mesoporous titania materials and then review several synthesis approaches. Currently, mesoporous titania nanoparticles (MTNs have attracted much attention in various fields, such as medicine, catalysis, separation and optics. Compared with bulk mesoporous titania materials, which are above a micrometer in size, nanometer-sized MTNs have additional properties, such as fast mass transport, strong adhesion to substrates and good dispersion in solution. However, it has generally been known that the successful synthesis of MTNs is very difficult owing to the rapid hydrolysis of titanium-containing precursors and the crystallization of titania upon thermal treatment. Finally, we review four emerging fields including photocatalysis, photovoltaic devices, sensing and biomedical applications of mesoporous titania materials. Because of its high surface area, controlled porous structure, suitable morphology and semiconducting behavior, mesoporous titania is expected to be used in innovative applications.

  3. Recent progress in mesoporous titania materials: adjusting morphology for innovative applications

    Science.gov (United States)

    Vivero-Escoto, Juan L; Chiang, Ya-Dong; Wu, Kevin; Yamauchi, Yusuke

    2012-01-01

    This review article summarizes recent developments in mesoporous titania materials, particularly in the fields of morphology control and applications. We first briefly introduce the history of mesoporous titania materials and then review several synthesis approaches. Currently, mesoporous titania nanoparticles (MTNs) have attracted much attention in various fields, such as medicine, catalysis, separation and optics. Compared with bulk mesoporous titania materials, which are above a micrometer in size, nanometer-sized MTNs have additional properties, such as fast mass transport, strong adhesion to substrates and good dispersion in solution. However, it has generally been known that the successful synthesis of MTNs is very difficult owing to the rapid hydrolysis of titanium-containing precursors and the crystallization of titania upon thermal treatment. Finally, we review four emerging fields including photocatalysis, photovoltaic devices, sensing and biomedical applications of mesoporous titania materials. Because of its high surface area, controlled porous structure, suitable morphology and semiconducting behavior, mesoporous titania is expected to be used in innovative applications. PMID:27877467

  4. Effect of thermal treating temperature on characteristics of silver-doped titania

    Institute of Scientific and Technical Information of China (English)

    CHAI Li-yuan; WEI Shun-wen; PENG Bing; LI Zhu-ying

    2008-01-01

    The silver-doped titania antibacterial agent was synthesized by mixing silver nitrate and the precursor of titania. Effects of thermal treatment on the properties of the silver-doped titania powders were investigated by thermal gravimeter/differential thermal analyzer(TG/DTA), scanning electron microscope(SEM), and X-ray diffractometer(XRD), respectively. The results show that the anatase phase forms in titania when the powder is calcined at 400 ℃. With the increase of the calcination temperature from 400 to 700 ℃ , the grains of titania agglomerate and the particle size increases from 14 to 23 nm, and the specific surface area decreases from 63 to 38m2g. As the powder is calcined at 700 ℃, titania starts to transform from anatase to rutile phase. The release rate of silver ion of powder treated at the relatively low temperature is larger than that of powder treated at the relatively high temperature. The antibacterial tests show that the antibacterial activity of silver-doped titania powders is excellent against E.coli and S. aureus, and the antibacterial activity of powders weakens with the increase of the calcination temperature.

  5. Synthesis and characterization of gadolinium-doped nanotubular titania for enhanced photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Liang [College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Cao, Lixin, E-mail: caolixin@ouc.edu.cn [College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Gao, Rongjie; Zhao, Yanling [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Zhang, Huibin; Xia, Chenghui [College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China)

    2014-12-25

    Graphical abstract: The Gd-doped titania nanotubes showed an increase in photocatalytic activity together with Gd/Ti ratio increase up 0.5%, followed by a rapid fall above 1.0%. - Highlights: • Enhanced Gd-doped titania nanotube photocatalysts have been synthesized. • Uniform Gd-doped titania nanoparticles were employed as raw materials. • Actual gadolinium contents in titania were precisely characterized by ICP-AES. • The distribution of Gd dopant was marked using element mapping. - Abstract: Gadolinium-doped titanium dioxide nanotubes were fabricated with a facile two-step route. Precursors Gd-doped titania nanoparticles were synthesized by a traditional sol–gel method. Hydrothermal process and acid treatment were employed afterwards, and Gd-doped titania nanotubes were finally obtained after calcination. The nominal doping concentration was expressed by Gd/Ti atomic ratio, ranged from 0% to 5.0%. Both the precursors and nanotubes were characterized by X-ray photoelectron spectra, inductively coupled plasma-atomic emission spectrometry, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectrometer, UV–vis diffusion reflection spectra and N{sub 2} absorption–desorption experiment. The photocatalytic activities were investigated using methyl orange as the model pollutant. The results indicated that Gd-doped titania nanotubes with nominal Gd/Ti of 0.5% possessed the optimal photocatalytic activity in our study.

  6. Multilayered Magnetic Gelatin Membrane Scaffolds

    Science.gov (United States)

    Samal, Sangram K.; Goranov, Vitaly; Dash, Mamoni; Russo, Alessandro; Shelyakova, Tatiana; Graziosi, Patrizio; Lungaro, Lisa; Riminucci, Alberto; Uhlarz, Marc; Bañobre-López, Manuel; Rivas, Jose; Herrmannsdörfer, Thomas; Rajadas, Jayakumar; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L.; Dediu, V. Alek

    2016-01-01

    A versatile approach for the design and fabrication of multilayer magnetic scaffolds with tunable magnetic gradients is described. Multilayer magnetic gelatin membrane scaffolds with intrinsic magnetic gradients were designed to encapsulate magnetized bioagents under an externally applied magnetic field for use in magnetic-field-assisted tissue engineering. The temperature of the individual membranes increased up to 43.7 °C under an applied oscillating magnetic field for 70 s by magnetic hyperthermia, enabling the possibility of inducing a thermal gradient inside the final 3D multilayer magnetic scaffolds. On the basis of finite element method simulations, magnetic gelatin membranes with different concentrations of magnetic nanoparticles were assembled into 3D multilayered scaffolds. A magnetic-gradient-controlled distribution of magnetically labeled stem cells was demonstrated in vitro. This magnetic biomaterial–magnetic cell strategy can be expanded to a number of different magnetic biomaterials for various tissue engineering applications. PMID:26451743

  7. Solid state consolidation nanocrystalline copper-tungsten using cold spray

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Aaron Christopher [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sarobol, Pylin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Argibay, Nicolas [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clark, Blythe [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Diantonio, Christopher [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    It is well known that nanostructured metals can exhibit significantly improved properties compared to metals with conventional grain size. Unfortunately, nanocrystalline metals typically are not thermodynamically stable and exhibit rapid grain growth at moderate temperatures. This severely limits their processing and use, making them impractical for most engineering applications. Recent work has shown that a number of thermodynamically stable nanocrystalline metal alloys exist. These alloys have been prepared as powders using severe plastic deformation (e.g. ball milling) processes. Consolidation of these powders without compromise of their nanocrystalline microstructure is a critical step to enabling their use as engineering materials. We demonstrate solid-state consolidation of ball milled copper-tantalum nanocrystalline metal powder using cold spray. Unfortunately, the nanocrystalline copper-tantalum powder that was consolidated did not contain the thermodynamically stable copper-tantalum nanostructure. Nevertheless, this does this demonstrates a pathway to preparation of bulk thermodynamically stable nanocrystalline copper-tantalum. Furthermore, it demonstrates a pathway to additive manufacturing (3D printing) of nanocrystalline copper-tantalum. Additive manufacturing of thermodynamically stable nanocrystalline metals is attractive because it enables maximum flexibility and efficiency in the use of these unique materials.

  8. Photoacoustic study of nanocrystalline silicon produced by mechanical grinding

    Energy Technology Data Exchange (ETDEWEB)

    Poffo, C.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Lima, J.C. de, E-mail: fsc1jcd@fisica.ufsc.b [Departamento de Fisica, Universidade Federal de Santa Catarina, Campus Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Souza, S.M.; Triches, D.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Grandi, T.A. [Departamento de Fisica, Universidade Federal de Santa Catarina, Campus Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Biasi, R.S. de [Secao de Engenharia Mecanica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

    2011-04-01

    Mechanical grinding (MG) was used to produce nanocrystalline silicon and its thermal and transport properties were investigated by photoacoustic absorption spectroscopy (PAS). The experimental results suggest that in as-milled nanocrystalline silicon for 10 h the heat transfer through the crystalline and interfacial components is similar, and after annealed at 470 {sup o}C the heat transfer is controlled by crystalline component.

  9. A ONE-STEP SURFACE MODIFICATION PROCEDURE TO PEG-GRAFTED NANO-TITANIA

    Institute of Scientific and Technical Information of China (English)

    Yong-liang Zhu; Bin Wang; Jian Yu; Zhao-xia Guo

    2007-01-01

    PEG (Polyethylene Glycol)-grafted nano-titania has been obtained in a one-step procedure using hexamethylene diisocyanate as the coupling agent and dibutyltin dilaurate as the catalyst in toluene at 80℃ and characterized qualitatively by FTIR and quantitatively by elemental analysis and thermogravimetric analysis. A comparison of nano-titania with two other commonly used inorganic nanoparticles, nano-silica and nano-alumina, is made, revealing that reactivity order is nanosilica > nano-alumina > nano-titania in view of PEG grafting. Possible mechanism of PEG grafting is also discussed.

  10. Enhanced photocleavage of water using titania nanotube arrays.

    Science.gov (United States)

    Mor, Gopal K; Shankar, Karthik; Paulose, Maggie; Varghese, Oomman K; Grimes, Craig A

    2005-01-01

    In this study highly ordered titania nanotube arrays of variable wall thickness are used to photocleave water under ultraviolet irradiation. We demonstrate that the wall thickness and length of the nanotubes can be controlled via anodization bath temperature. We find that the nanotube wall thickness is a key parameter influencing the magnitude of the photoanodic response and the overall efficiency of the water-splitting reaction. For 22 nm inner pore diameter nanotube arrays, those fabricated in a 5 degrees C anodization bath, 224 nm length and 34 nm wall thickness produced a photoanodic response that was thrice that of a nanotube array fabricated in a 50 degrees C anodization bath, 120 nm length and 9 nm wall-thickness. At high anodic polarization, above 1 V, the quantum efficiency under 337 nm illumination was greater than 90%. For the 5 degrees C anodization bath samples (22 nm pore-diameter, 34 nm wall thickness), upon 320-400 nm illumination at an intensity of 100 mW/cm(2), hydrogen gas was generated at the power-time normalized rate of 960 micromol/h W (24 mL/h W) at an overall conversion efficiency of 6.8%. To the best of our knowledge, this hydrogen generation rate is the highest reported for a titania-based photoelectrochemical cell.

  11. Suppressed primary osteoblast functions on nanoporous titania surface.

    Science.gov (United States)

    Zhao, Lingzhou; Mei, Shenglin; Wang, Wei; Chu, Paul K; Zhang, Yumei; Wu, Zhifen

    2011-01-01

    Titiania nanotubes have large potential in medical implant applications but their tissue compatibility is still controversial. Considering that the biological behavior of primary osteoblasts is closer to the in vivo situation than other common cell lines, we investigate the response of primary osteoblasts on anodized nanotextured titania surfaces. Two nanotextured surface morphologies, namely the 5 V anodized surface with a pore diameter of 25 nm and the 20 V anodized surface with a tube diameter of 80 nm are chosen for this study. Initial cell adhesion is not obviously affected by the anodized surfaces. With the exception of slightly higher intracellular alkaline phosphatase activity and more extracellular matrix deposition, cell growth, and cell differentiation represented by the expressions of osteogenesis-related genes are impaired on both anodized surfaces. This may be attributed to the compromised focal contact formation on the anodized surfaces. The difference in the phenotypes of the primary osteoblasts and the osteoblastic cell lines may partly account for the controversy in osteoblast cytocompatibility on titania nanotubes.

  12. Synthesis of Mesoporous Titania with Surfactant and its Characterization

    Directory of Open Access Journals (Sweden)

    T. Benkacem

    2008-01-01

    Full Text Available A mesoporous titania was obtained by gelation from Ti-alkoxide in acidic solutions with addition of surfactant cetyltrimetylammonium bromide (CH3(CH215N(CH33Br using a sol-gel process. The effects of surfactant concentration on synthesis of mesoporous titania were studied. The structural characterisation was studied by differential thermal analysis, infrared spectroscopy, X-ray diffraction. Studies by X-ray diffraction showed that crystallisation of TiO2 powder occurs at 200°C, above 200°C we obtained a mixture of two forms-Anatase and rutile. The textural characterisation by nitrogen adsorption-desorption allowed us to observe the variation of the surface area, porous volume and pore diameters according to temperature and [CTAB]/[Ti-alkoxide] molar ratio. The analysis of the results shows that addition of surfactant residue increases considerably its pore diameters. The deposit thin layers has been realized with a sol prepared with the destabilization of colloidal solutions process. Scanning electron-spectroscopy observation for thermally treated (at 400 and 600°C samples, showed homogeneous layers without cracking.

  13. Titania preparation from soda roasted slag using sulfuric acid solution

    Directory of Open Access Journals (Sweden)

    El-Sayed A. Manaa

    2016-11-01

    Full Text Available This work deals with treatment of the sodium titanate cake results from roasted titania slag using 60% sulfuric acid solution. The working sample produced by roasting titania slag with NaCO3 at 850 °C. After roasting V and Cr species as impurities in the roasted sample are converted to water soluble species as NaVO3 and Na2CrO4 before acid treatment however, the insoluble sodium titanate products (NaFeTiO4, Na8Ti5O14, Na6Ti2O7 and Na2TiO4 are then subjected to H2SO4 acid dissolution. The produced sulfate solution is subjected to hydrolysis step in presence of oxalic acid as a reducing agent. The hydrolyzed precipitate after filtration and washing with H2SO4 solution and warm water is dried at 100 °C and calcinated at 850 °C to prepare high pure TiO2 (99.8% besides removing ferrous sulfate (FeSO4 as a byproduct from the sulfate solution.

  14. Titania-supported silver-based bimetallic nanoparticles as photocatalysts.

    Science.gov (United States)

    Barakat, M A; Al-Hutailah, R I; Hashim, M H; Qayyum, E; Kuhn, J N

    2013-06-01

    Photocatalytic process has shown recently a great potential as an environmental friendly and clean remediation technology for organic pollutants in wastewater. This work described the synthesis of silver-based bimetallic nanoparticles using colloid chemistry and the subsequent immobilization onto titania to form composite photocatalytic materials (titania-supported Ag-Pt nanoparticles). The photocatalysts were characterized by X-ray diffraction, electron microscopy, and nitrogen physisorption. The catalytic activity of the photocatalysts was evaluated by photocatalytic degradation of phenol and 2-chlorophenol (2-CP) in synthetic wastewater solutions. The photocatalytic processes were conducted in a batch photoreactor containing appropriate solutions of phenol and 2-CP with UV irradiation of 450 W. UV-visible spectrophotometer was used for analyzing the concentration of phenol and 2-CP in solutions. Parameters affecting the photocatalytic process such as the solution pH, phenol and 2-CP concentrations, and catalyst concentration were investigated. The results obtained revealed that TiO(2)-supported Ag/Pt nanoparticles showed a higher activity for UV-photocatalytic degradation of both phenol and 2-CP pollutants in the solution (as compared to the plain rutile TiO(2)). The photodegradation processes were optimized by the 0.5-g/L catalyst with a pollutant concentration of 50 mg/L for all the samples. Complete degradation for both phenol and 2-CP was achieved after 120 min.

  15. Photocatalytic Properties of Size-Controlled Titania Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Takeshi Hashishin

    2011-01-01

    Full Text Available The titania nanotube arrays (TNAs with smooth surface was synthesized by anodization of titanium foil with 3 cm2 in square area using the electrolyte composed of 0.2 wt% NH4F and 0.5 vol% H2SO4 in ethylene glycol in order to evaluate the methylene blue photodegradation under ultra-violet irradiation. The tube length and inner diameter as a size parameter were controlled by the anodization time from 5 to 10 h and applied voltage from 10 to 50 V. The titania nanotube arrays (TNAs annealed at 300 to 500°C were assigned to anatase phase, and TNAs at 600°C had both phase of anatase and rutile. The crystallite size and the apparent rate constant were increased with the increase in the annealing temperature of TNAs from 300 to 500°C. The bigger crystallite size of TNAs is suggested to be related to the increase in the amount of hole at the valence band, leading to the decrease in the apparent rate constant of MB degradation. Interestingly, the four kinds of linear relationship with the apparent rate constant were seen in both the inner diameter of TNAs and the length. Consequently, the apparent rate constant strongly depended on inner diameter of TNAs.

  16. Organically modified titania nanoparticles for sustained drug release applications.

    Science.gov (United States)

    Sethi, Komal; Roy, Indrajit

    2015-10-15

    In this paper, we report the synthesis, characterization of drug-doped organically modified titania nanoparticles, and their applications in sustained drug release. The drug-doped nanoparticles were synthesized in the hydrophobic core of oil-in-water microemulsion medium. Structural aspects obtained through TEM and FESEM depicted that organically modified titania nanoparticles are monodispersed with spherical morphology, with an average size of around 200 nm. Their polymorphic forms and porosity were determined using powder XRD and BET, respectively, which showed that they are present in the anatase form, with a surface area of 136.5 m(2)/g and pore-diameter of 5.23 nm. After synthesis and basic structural characterizations, optical properties were studied for both fluorophore and drug encapsulated nanoparticles. The results showed that though the optical properties of the fluorophore are partially diminished upon nanoencapsulation, it became more stable against chemical quenching. The nanoparticles showed pH-dependent drug release pattern. In vitro studies showed that the nanoparticles were efficiently uptaken by cells. Cell viability assay results showed that though the placebo nanoparticles are non-cytotoxic, the drug-doped nanoparticles show drug-induced toxicity. Therefore, such porous nanoparticles can be used in non-toxic drug delivery applications.

  17. Physical adsorption of anisotropic titania nanoparticles onto poly(2-vinylpyridine) latex and characterisation of the resulting nanocomposite particles.

    Science.gov (United States)

    Fielding, Lee A; Armes, Steven P; Staniland, Paul; Sayer, Robert; Tooley, Ian

    2014-07-15

    Four poly(2-vinylpyridine) latexes with intensity-average mean diameters ranging between 246 and 955nm were prepared by aqueous emulsion polymerisation. These latexes were characterised by transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, aqueous electrophoresis, disc centrifuge photosedimentometry and thermogravimetry. The adsorption of rice grain-shaped nano-sized titania particles onto the surface of these latex particles from aqueous solution was investigated. It was found that the titania particles adsorb strongly at pH 10 and the optimal loading and packing density of titania was investigated for each latex. The resulting core-shell P2VP-titania nanocomposite particles were characterised in terms of their titania contents, surface coverages and colloidal stabilities. UV-Vis spectra were recorded for the titania nanoparticles, the original P2VP latexes and the poly(2-vinylpyridine)-titania nanocomposite particles. It was found that, for the larger nanocomposite particles, UV-Vis absorption was dominated by the latex core, whereas the smaller P2VP-titania nanocomposite particles exhibited UV attenuation to longer wavelengths compared to both the bare latex and the titania particles. The poly(2-vinylpyridine) cores were selectively removed by calcination of the nanocomposite particles and the resulting hollow titania structures were investigated by transmission electron microscopy.

  18. Hydroxyapatite nucleated and grown on nano titania particles enhances recruitment of Escherichia coli for subsequent photocatalytic elimination

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jing; Liu, Yi; Liu, Yuxin; Li, Hua, E-mail: lihua@nimte.ac.cn

    2015-02-01

    Titania-hydroxyapatite (HA) nanocomposites were fabricated by wet chemical synthesis approach. HA exhibited crystallographic orientation of nucleation on nano titania particle, forming the composite particles with titania being partially enwrapped with HA. Microstructural characterization by high resolution transmission electron microscopy revealed coherent interfacial bond of (110) and (222) planes of HA crystal with (101) plane of anatase. The HA layer promoted significantly recruitment of Escherichia coli bacteria onto the titania-based particles for subsequent photocatalytic killing. Less extent of enwrapping of HA on titania particle, as accomplished by increasing the aging time of HA suspension, gave rise to better capability of photocatalytic degradation of methylene blue and sterilization of the bacteria. The novel HA-enwrapped titania powder shows great potential for environmental applications. - Highlights: • Titania-hydroxyapatite nanocomposite powder was fabricated with cladding structure. • Hydroxyapatite nucleated and grew on titania particle with preferred orientation. • Hydroxyapatite layer promotes recruitment of Escherichia coli onto titania-based particles. • The titania-hydroxyapatite particles show excellent antibacterial performances. • The nanocomposite powder exhibits excellent photocatalytic performances.

  19. Facile synthesis of titania/hyperbranched polyglycidol nanohybrids with controllable morphologies: from solid spheres, capsules to tubes

    Energy Technology Data Exchange (ETDEWEB)

    Li Haiqing; Zhang Lin; Jo, Jung Kyu; Ha, Chang-Sik; Shchipunov, Yury A.; Kim, Il, E-mail: ilkim@pusan.ac.kr [Pusan National University, WCU Center for Synthetic Polymer Bioconjugate Hybrid Materials, Department of Polymer Science and Engineering (Korea, Republic of)

    2011-05-15

    Titania/Hyperbranched polyglycidol (HBP) nanohybrids with tunable morphologies have been synthesized via a sol-gel process at ambient temperature. One-shot addition of varied amounts of titanium precursor tetraisopropoxide (TTIP) yields spherical titania/HBP solid particles with tunable size, while a controlled addition of TTIP results in spherical titania/HBP capsules. The average outer and inner diameters of the resultant capsules are also controllable according to the amount of TTIP via an Oswald ripening process. In addition, the modality of additional water supplied in the reaction systems can tune the morphologies of the resulting titania/HBP particles from nanocapsules to nanotubes owing to the accelerated hydrolysis rate of TTIP. The tunability in morphologies of the titania/HBP nanostructures ranging from solid spheres, capsules to tubes could be attributed to the self-assembly of a large amount of titania/HBP aggregates in a rapid, controlled and anisotropic manner, respectively. Surprisingly, by means of HBP contained in the resulting titania/HBP nanostructures, the gold nanoparticles are in situ generated and encapsulated into titania/HBP matrix in the absence of additional reducing agent. The as-prepared gold nanoparticles functionalized titania/HBP hybrids exhibit excellent catalytic function toward the reduction of 4-nitrophenol. This strategy demonstrates a typical example for functionalizing the titania/HBP hybrids targeted to specific applications.

  20. An Investigation on the Mechanical Behavior of Roll-Bonded Multilayered Cu-Nb Nanocrystalline Materials

    Science.gov (United States)

    2015-02-12

    SECURITY CLASSIFICATION OF: 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES 12. DISTRIBUTION AVAILIBILITY STATEMENT 6...elevated temperature, which can be potentially interesting for Army applications. Tensile strength and fracture morphologies are discussed. The views...fracture morphologies are discussed. (a) Papers published in peer-reviewed journals (N/A for none) Enter List of papers submitted or published that

  1. Multilayer optical calculations

    CERN Document Server

    Byrnes, Steven J

    2016-01-01

    When light hits a multilayer planar stack, it is reflected, refracted, and absorbed in a way that can be derived from the Fresnel equations. The analysis is treated in many textbooks, and implemented in many software programs, but certain aspects of it are difficult to find explicitly and consistently worked out in the literature. Here, we derive the formulas underlying the transfer-matrix method of calculating the optical properties of these stacks, including oblique-angle incidence, absorption-vs-position profiles, and ellipsometry parameters. We discuss and explain some strange consequences of the formulas in the situation where the incident and/or final (semi-infinite) medium are absorptive, such as calculating $T>1$ in the absence of gain. We also discuss some implementation details like complex-plane branch cuts. Finally, we derive modified formulas for including one or more "incoherent" layers, i.e. very thick layers in which interference can be neglected. This document was written in conjunction with ...

  2. Multilayer graphene rubber nanocomposites

    Science.gov (United States)

    Schartel, Bernhard; Frasca, Daniele; Schulze, Dietmar; Wachtendorf, Volker; Krafft, Bernd; Morys, Michael; Böhning, Martin; Rybak, Thomas

    2016-05-01

    Multilayer Graphene (MLG), a nanoparticle with a specific surface of BET = 250 m2/g and thus made of only approximately 10 graphene sheets, is proposed as a nanofiller for rubbers. When homogenously dispersed, it works at low loadings enabling the replacement of carbon black (CB), increase in efficiency, or reduction in filler concentration. Actually the appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing and mechanical properties of different rubbers, as shown for Chlorine-Isobutylene-Isoprene Rubber (CIIR), Nitrile-Butadiene Rubber (NBR), Natural Rubber (NR), and Styrene-Butadiene Rubber (SBR). A mere 3 phr of MLG tripled the Young's modulus of CIIR, an effect equivalent to 20 phr of carbon black. Similar equivalents are observed for MLG/CB mixtures. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards fire behavior. The later shown by the reduction in heat release rate in the cone calorimeter. The higher the nanofiller concentration is (3 phr, 5 phr, and 10 phr was investigated), the greater the improvement in the properties of the nanocomposites. Moreover, the MLG nanocomposites improve stability of mechanical properties against weathering. An increase in UV-absorption as well as a pronounced radical scavenging are proposed and were proved experimentally. To sum up, MLG is interesting as a multifunctional nanofiller and seems to be quite ready for rubber development.

  3. Studies on Anion Promoted Titania.1: Preparation, Characterization, and Catalytic Activity toward Alcohol and Cumene Conversion Reactions of Phosphated Titania.

    Science.gov (United States)

    Parida; Acharya; Samantaray; Mishra

    1999-09-15

    Phosphate impregnated titania samples with varying amount of phosphate have been prepared by solid-solid kneading as well as aqueous impregnation method. All the samples are characterized by XRD, TG-DTA, and N(2) adsorption-desorption isotherm. Surface area is found to increase with the increase in phosphate content up to 7.5 wt% loading and thereafter decreases. The average pore diameter and crystallite size of titania decreases with the addition of phosphate. However, total acidity (determined by base adsorption method) and the catalytic activity increases with the increase in phosphate content up to 10 wt%. Phosphated samples prepared using phosphoric acid as the source of phosphate exhibit higher acidity compared to the samples prepared using (NH(4))(3)PO(4). However, the sample prepared from (NH(4))(3)PO(4) shows the presence of both acid and basic sites. Though from the cumene conversion study it is understood that phosphated samples contain both Lewis and Brønsted acid sites, the latter predominates over the former. Copyright 1999 Academic Press.

  4. New triblock copolymer templates, PEO-PB-PEO, for the synthesis of titania films with controlled mesopore size, wall thickness, and bimodal porosity.

    Science.gov (United States)

    Ortel, Erik; Fischer, Anna; Chuenchom, Laemthong; Polte, Jörg; Emmerling, Franziska; Smarsly, Bernd; Kraehnert, Ralph

    2012-01-23

    The synthesis and properties of a series of new structure-directing triblock copolymers with PEO-PB-PEO structure (PEO = poly(ethylene oxide) and PB = polybutadiene) and their application as superior pore-templates for the preparation of mesoporous titania coatings are reported. Starting from either TiCl4 or from preformed TiO2 nanocrystalline building blocks, mesoporous crystalline titanium oxide films with a significant degree of mesoscopic ordered pores are derived, and the pore size can be controlled by the molecular mass of the template polymer. Moreover, the triblock copolymers form stable micelles already at very low concentration, i.e., prior to solvent evaporation during the evaporation-induced self-assembly process (EISA). Consequently, the thickness of pore walls can be controlled independently of pore size by changing the polymer-to-precursor ratio. Thus, unprecedented control of wall thickness in the structure of mesoporous oxide coatings is achieved. In addition, the micelle formation of the new template polymers is sufficiently distinct from that of typical commercial PPO-PEO-PPO polymers (Pluronics; PPO = poly(propylene oxide)), so that a combination of both polymers facilitates bimodal porosity via dual micelle templating.

  5. Solution equilibrium behind the room-temperature synthesis of nanocrystalline titanium dioxide

    Science.gov (United States)

    Seisenbaeva, Gulaim A.; Daniel, Geoffrey; Nedelec, Jean-Marie; Kessler, Vadim G.

    2013-03-01

    Formation of nanocrystalline and monodisperse TiO2 from a water soluble and stable precursor, ammonium oxo-lactato-titanate, (NH4)8Ti4O4(Lactate)8.4H2O, often referred to as TiBALDH or TALH, is demonstrated to be due to a coordination equilibrium. This compound, individual in the solid state, exists in solution in equilibrium with ammonium tris-lactato-titanate, (NH4)2Ti(Lactate)3 and uniform crystalline TiO2 nanoparticles (anatase) stabilized by surface-capping with lactate ligands. This equilibrium can be shifted towards nano-TiO2via application of a less polar solvent like methanol or ethanol, dilution of the solution, introduction of salts or raising the temperature, and reverted on addition of polar and strongly solvating media such as dimethyl sulfoxide, according to NMR. Aggregation and precipitation of the particles were followed by DLS and could be achieved by a decrease in their surface charge by adsorption of strongly hydrogen-bonding cations, e.g. in solutions of ammonia, ethanolamine or amino acid arginine or by addition of ethanol. The observed equilibrium may be involved in formation of nano-titania on the surface of plant roots exerting chelating organic carboxylate ligands and thus potentially influencing plant interactions.Formation of nanocrystalline and monodisperse TiO2 from a water soluble and stable precursor, ammonium oxo-lactato-titanate, (NH4)8Ti4O4(Lactate)8.4H2O, often referred to as TiBALDH or TALH, is demonstrated to be due to a coordination equilibrium. This compound, individual in the solid state, exists in solution in equilibrium with ammonium tris-lactato-titanate, (NH4)2Ti(Lactate)3 and uniform crystalline TiO2 nanoparticles (anatase) stabilized by surface-capping with lactate ligands. This equilibrium can be shifted towards nano-TiO2via application of a less polar solvent like methanol or ethanol, dilution of the solution, introduction of salts or raising the temperature, and reverted on addition of polar and strongly solvating

  6. Preparation and characterization of crystalline titania film on polyimide substrate by SILAR

    Science.gov (United States)

    Shi, Yaping; Wu, Yiyong; Sun, Chengyue; Huo, Mingxue

    2014-10-01

    Crystalline titania films were prepared on the flexible polyimide (Kapton) substrates using the successive ionic layer adsorption and reaction (SILAR) technique modified with mixed organic amine template agents at room temperature. The titania film with the organic amine template agents presents orderly stacked morphology with cross linked V-shaped strips, and it composes of mainly anatase and minor rutile phases with N doping. Structural and morphology analysis indicates that there includes two parallel deposition growth processes: One is adsorption of the template agents and reaction with Ti4+ ions on the constraint region; and the other is a normal SILAR process of including the adsorption of Ti4+ ions and reaction with hydroxyl groups. The organic amine templates and their specific adsorption induce and direct the crystallization of the titania films. Crystal structure of the titania film was confirmed by its excellent photo catalytic property of the films, detected by the degradation test of MB.

  7. Investigations of mechanical and wear properties of alumina/titania/fire-clay reinforced epoxy composites

    Science.gov (United States)

    Patel, Vinay Kumar; Chauhan, Shivani; Sharma, Aarushi

    2016-05-01

    In this work, the effect of various particulates (alumina, titania, fire clay) reinforcements on mechanical and wear properties of epoxy composites have been studied with a prime motive of replacing the costly alumina and titania by much economical fire clay for high mechanical strength and/or wear resistant materials. Fire clay based epoxy composites delivered better mechanical (both tensile and impact) properties than the alumina filled or neat epoxy composites and slightly lower than titania reinforced composites, which qualified the fire clay a very suitable cost effective alternatives of both alumina and titania for high mechanical strength based applications. However, the poor wear behavior of fire clay reinforced composites revealed its poor candidacy for wear and tear applications.

  8. Macrostructure-dependent photocatalytic property of high-surface-area porous titania films

    Directory of Open Access Journals (Sweden)

    T. Kimura

    2014-11-01

    Full Text Available Porous titania films with different macrostructures were prepared with precise control of condensation degree and density of the oxide frameworks in the presence of spherical aggregates of polystyrene-block-poly(oxyethylene (PS-b-PEO diblock copolymer. Following detailed explanation of the formation mechanisms of three (reticular, spherical, and large spherical macrostructures by the colloidal PS-b-PEO templating, structural variation of the titania frameworks during calcination were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. Then, photocatalytic performance of the macroporous titania films was evaluated through simple degradation experiments of methylene blue under an UV irradiation. Consequently, absolute surface area of the film and crystallinity of the titania frameworks were important for understanding the photocatalytic performance, but the catalytic performance can be improved further by the macrostructural design that controls diffusivity of the targeted molecules inside the film and their accessibility to active sites.

  9. Capture of mercury in combustion systems by in situ-generated titania particles with UV irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C.Y.; Lee, T.G.; Tyree, G.; Arar, E.; Biswas, P. [University of Cincinnati, Cincinnati, OH (United States). Dept. of Civil and Environmental Engineering

    1998-10-01

    In situ-generated sorbent titania particles with ultraviolet (UV) irradiation have been shown to be effective in capture of mercury in combustor exhausts. Results of experiments conducted with the (1) sorbent precursor only, (2) mercury only, (3) mercury and UV irradiation, and (4) mercury, titania, and UV irradiation are presented to elucidate the mechanisms of the capture process. Capture efficiencies (percentage of Hg captured on the filter) as high as 96% were measured for mercury by titania with UV irradiation. A very high surface area titania sorbent was first formed, with mercury vapors condensing onto this surface, followed by photocatalytic oxidation and binding with the sorbent particles. The process has significant potential as a low-cost methodology for mercury control in practical combustion systems. Minimal retrofitting may be necessary as conventional particulate control devices such as electrostatic precipitators have coronas with UV radiation present.

  10. Superhydrophilicity-assisted preparation of transparent and visible light activated N-doped titania film.

    Science.gov (United States)

    Xu, Qing Chi; Wellia, Diana V; Amal, Rose; Liao, Dai Wei; Loo, Say Chye Joachim; Tan, Timothy Thatt Yang

    2010-07-01

    A novel and environmental friendly method was developed to prepare transparent, uniform, crack-free and visible light activated nitrogen doped (N-doped) titania thin films without the use of organic Ti precursors and organic solvents. The N-doped titania films were prepared from heating aqueous peroxotitanate thin films deposited uniformly on superhydrophilic uncoated glass substrates. The pure glass substrates were superhydrophilic after being heated at 500 degrees C for 1 h. Nitrogen concentrations in the titania films were adjusted by changing the amount of ammonia solution. The optimal photocatalytic activity of the N-doped titania films was about 14 times higher than that of a commercial self-cleaning glass under the same visible light illumination. The current reported preparative technique is generally applicable for the preparation of other thin films.

  11. HOT ELUENT CAPILLARY LIQUID CHROMATOGRAPHY USING ZIRCONIA AND TITANIA BASED STATIONARY PHASES. (R825344)

    Science.gov (United States)

    AbstractHigh speed capillary liquid chromatographic separations using a simple home made system constructed from readily available inexpensive components have been studied. Using thermally stable zirconia and titania based packing, the separation of eight alkylbenzene...

  12. Attachment of Lipase on Amino Functionalized Titania Submicrospheres via Covalent Binding

    Institute of Scientific and Technical Information of China (English)

    WU Hong; LIANG Yan-peng; SHI Jia-fu; WANG Xiao-li

    2013-01-01

    A facile and effective method for immobilized lipase was presented.The titania submicrospheres were synthesized via a modified sol-gel method followed by amino functionalization through the chelation between dopamine and titania.Lipase was covalently attached on the functionalized titania surface using glutaraldehyde as the cross linking agent.The loading ratio and relative activity of the immobilized lipase were 230 mg/g titania submicrospheres and 65%,respectively.The kinetic parameters including the Michaelis constant (Km) and the maximum reaction rate (Vmax) changed slightly after immobilization.Compared to free lipase,the immobilized lipase showed favorable pH stability,thermostability,recycling stability and storage stability.The immobilized lipase retained 90% activity after incubation at 50 ℃ for 2 h,while the free lipase retained only 60% activity.The immobilized lipase retained more than 80% activity after 8 batches.

  13. Superhydrophilicity-assisted preparation of transparent and visible light activated N-doped titania film

    Science.gov (United States)

    Xu, Qing Chi; Wellia, Diana V.; Amal, Rose; Liao, Dai Wei; Loo, Say Chye Joachim; Tan, Timothy Thatt Yang

    2010-07-01

    A novel and environmental friendly method was developed to prepare transparent, uniform, crack-free and visible light activated nitrogen doped (N-doped) titania thin films without the use of organic Ti precursors and organic solvents. The N-doped titania films were prepared from heating aqueous peroxotitanate thin films deposited uniformly on superhydrophilic uncoated glass substrates. The pure glass substrates were superhydrophilic after being heated at 500 °C for 1 h. Nitrogen concentrations in the titania films were adjusted by changing the amount of ammonia solution. The optimal photocatalytic activity of the N-doped titania films was about 14 times higher than that of a commercial self-cleaning glass under the same visible light illumination. The current reported preparative technique is generally applicable for the preparation of other thin films.

  14. Controllable Synthesis of Titania Nanocrystals with Different Morphologies and Application to the Degradation of Phenol

    Institute of Scientific and Technical Information of China (English)

    CHEN Da-wei; SHI Jin-e; YAN Ji-chang; WANG Yue-hong; YAN Fu-cheng; SHANG Shu-xia; XUE Jing

    2008-01-01

    Titania nanocrystals with different morphologies were prepared using the hydrothermal method via controlling the pH values of solution, the ratio of reactants, temperature, and time of the hydrothermal reaction. The experimental results showed that uniform rod-like titania particles with an average aspect ratio of 6:1 could be obtained under the conditions of pH=11, n(TBOT):n(TEA)=1:2, hydrothermal treatment at 150 ℃ for 24 h. When pH<10,spherical titania nanocrystals could be obtained; with increasing the pH value, the diameter became smaller. Finally, the smallest size of the particles could reach 7 nm. Nanocrystals with uniformly well-dispersed and perfect crystallographic form were obtained via the above method. Phenol was used as the degradation model for testing the photocatalytical activity of the titania nanocrystals with different morphologies.

  15. Macrostructure-dependent photocatalytic property of high-surface-area porous titania films

    Science.gov (United States)

    Kimura, T.

    2014-11-01

    Porous titania films with different macrostructures were prepared with precise control of condensation degree and density of the oxide frameworks in the presence of spherical aggregates of polystyrene-block-poly(oxyethylene) (PS-b-PEO) diblock copolymer. Following detailed explanation of the formation mechanisms of three (reticular, spherical, and large spherical) macrostructures by the colloidal PS-b-PEO templating, structural variation of the titania frameworks during calcination were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. Then, photocatalytic performance of the macroporous titania films was evaluated through simple degradation experiments of methylene blue under an UV irradiation. Consequently, absolute surface area of the film and crystallinity of the titania frameworks were important for understanding the photocatalytic performance, but the catalytic performance can be improved further by the macrostructural design that controls diffusivity of the targeted molecules inside the film and their accessibility to active sites.

  16. Photocatalytic polymerization induced by a transparent anatase titania aqueous sol and fabrication of polymer composites

    Directory of Open Access Journals (Sweden)

    2010-06-01

    Full Text Available The surface modification of the anatase titania nanoparticles prepared via a controlled nonhydrolytic sol-gel process is achieved by the formation of the bidentate coordination between titania and methacrylic acid (MAA molecules. The in situ photocatalytic polymerization of methyl methacrylate (MMA monomer is initiated by surface modified anatase titania nanoparticles under Xe lamp irradiation. A variety of techniques including differential scanning calorimetry (DSC, thermo-gravimetric analysis (TGA and scanning electron microscopy (SEM are employed to characterize the resulting materials. The glass transition temperatures and the thermal stabilities of polymethyl methacrylate (PMMA composite materials prepared via photocatalytic polymerization are enhanced compared with pure polymer. The partial aggregation of titania nanoparticles in PMMA composite films is derived from the surface polymerization of MMA, which makes the inorganic particles hydrophobic and drives them to the water/oil interfaces.

  17. Unfolding single- and multilayers

    Science.gov (United States)

    Llorens, Maria-Gema; Bons, Paul D.; Griera, Albert; Gomez-Rivas, Enrique

    2014-05-01

    When planar structures (e.g. sedimentary layers, veins, dykes, cleavages, etc.) are subjected to deformation, they have about equal chances to be shortened or stretched. The most common shortening and stretching structures are folds and boudinage, respectively. However, boudinage requires additional deformation mechanisms apart from viscous flow, like formation of fractures or strain localization. When folded layers are subjected to extension, they could potentially unfold back to straight layers. Although probably not uncommon, this would be difficult to recognize. Open questions are whether folded layers can unfold, what determines their mechanical behaviour and how we can recognize them in the field. In order to approach these questions, we present a series of numerical experiments that simulate stretching of previously folded single- and multi-layers in simple shear, using the two dimensional numerical modelling platform ELLE, including the finite element module BASIL that calculates viscous deformation. We investigate the parameters that affect a fold train once it rotates into the extensional field. The results show that the unfolding process strongly depends on the viscosity contrast between the layer and matrix (Llorens et al., 2013). Layers do not completely unfold when they experience softening before or during the stretching process or when other neighbouring competent layers prevent them from unfolding. The foliation refraction patterns are the main indicators of unfolded folds. Additionally, intrafolial folds and cusp-like folds adjacent to straight layers, as well as variations in fold amplitudes and limb lengths of irregular folds can also be used as indicators of stretching of a layer after shortening and folding. References: Llorens, M-.G., Bons, P.D., Griera, A. and Gomez-Rivas, E. 2013. When do folds unfold during progressive shear?. Geology, 41, 563-566.

  18. Sintering and mechanical properties of the alumina–tricalcium phosphate–titania composites

    Energy Technology Data Exchange (ETDEWEB)

    Sakka, Siwar, E-mail: sakka.siwar@yahoo.fr; Bouaziz, Jamel; Ben Ayed, Foued

    2014-07-01

    The objective of this study was to determine the effect of the content of titania and the sintering process on the transformation phase, the densification, the rupture strength and the microstructures of the alumina–10 wt.% tricalcium phosphate composites. After the sintering process, the samples were examined by using {sup 31}P and {sup 27}Al magic angle scanning nuclear magnetic resonance, X-ray powder diffraction and scanning electron microscopy analysis. The Brazilian test was used to measure the rupture strength of the samples. The present results provide new information about solid-state reactivity in the ternary system α-alumina-β-tricalcium phosphate–anatase–titania. The differential thermal analysis of the α-alumina-β-tricalcium phosphate–titania composites shows two endothermic peaks, at 1360 °C and at 1405 °C, which are caused by the reactions between titania/alumina and titania/tricalcium phosphate, respectively. Thus, the presence of titania in the alumina–10 wt.% tricalcium phosphate leads to the formation of β-Al{sub 2}TiO{sub 5} at 1360 °C. At 1600 °C, the alumina–10 wt.% tricalcium phosphate–5 wt.% titania composites displayed the highest rupture strength (74 MPa), compared to the alumina–10 wt.% tricalcium phosphate composites (13.5 MPa). Accordingly, the increase of the rupture strength is due to the formation of the new β-Al{sub 2}TiO{sub 5} phase. - Highlights: • We examine the mechanical properties of bioceramics. • We measure the rupture strength by the Brazilian test. • We characterize the alumina–10 wt.% tricalcium phosphate–titania composites.

  19. Preparation and corrosion behavior evaluation of amalgam/titania nano composite

    OpenAIRE

    Neda Bahremandi Tolou; Mohammadhossein Fathi; Ahmad Monshi; Vajihesadat Mortazavi; Farzaneh Shirani

    2011-01-01

    Background: Many attempts have been performed and continued for improvement of dental amalgam properties during last decades. The aim of present research was fabrication and characterization of amalgam/titania nano composite and evaluation of its corrosion behavior. Materials and Methods: In this experimental research, nano particles of titania were added to initial amalgam alloy powder and then, dental amalgam was prepared. In order to investigate the effect of nano particle amounts on p...

  20. Enhanced Photocatalytic Activity for Degradation of Methyl Orange over Silica-Titania

    OpenAIRE

    Yaping Guo; Shaogui Yang; Xuefei Zhou; Chunmian Lin; Yajun Wang; Weifeng Zhang

    2011-01-01

    Silica-modified titania (SMT) powders with different atomic ratios of silica to titanium (Rx) were successfully synthesized by a simple ultrasonic irradiation technique. The prepared samples were characterized by X-ray diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible spectroscopy. The specific surface area was measured according to BET theory. Results indicate that the addition of silica to titania c...

  1. Biological performance of titania containing phosphate-based glasses for bone tissue engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Abou Neel, Ensanya Ali, E-mail: eabouneel@kau.edu.sa [Division of Biomaterials, Conservative Dental Sciences Department, King Abdulaziz University, Jeddah (Saudi Arabia); Biomaterials Department, Faculty of Dentistry, Tanta University, Tanta (Egypt); Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, 256 Gray' s Inn Road, London WC1X 8LD (United Kingdom); Chrzanowski, Wojciech [The University of Sydney, Faculty of Pharmacy, Pharmacy and Bank Building, NSW2006 (Australia); Department of Nanobiomedical Science and BK21 Plus NBM Global Reserch Center for Regenerative Medicine, Dankook University, Cheonan 330-714 (Korea, Republic of); Knowles, Jonathan Campbell, E-mail: j.knowles@ucl.ac.uk [Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, 256 Gray' s Inn Road, London WC1X 8LD (United Kingdom); Department of Nanobiomedical Science and BK21 Plus NBM Global Reserch Center for Regenerative Medicine, Dankook University, Cheonan 330-714 (Korea, Republic of)

    2014-02-01

    The interplay between glass chemistry, structure, degradation kinetics, and biological activity provides flexibility for the development of scaffolds with highly specific cellular response. The aim of this study was therefore to investigate the role of titania inclusion into the phosphate-based glass on its ability to stimulate osteoblast-like human osteosarcoma (HOS) cells to adhere, proliferate and differentiate. In depth morphological and biochemical characterisation was performed on HOS cells cultured on the surface of glass discs. Cell proliferation was also studied in the presence of the glass extract. Cell differentiation, through osteoblast phenotype genes, alkaline phosphatase (ALP) activity and osteocalcin production, was carried out using normal or osteogenic media. Both Thermanox® and titania free glass were used as controls. The data demonstrated that titania inclusion provides desired cytocompatible surface that supported initial cell attachment, sustained viability, and increased cell proliferation similar or significantly higher than Thermanox®. The modified glasses regulated osteoblastic cell differentiation as detected by osteoblast phenotype gene transcription and upregulated ALP and osteocalcin expression. Using osteogenic media had no significant effect on ALP activity and osteocalcin expression. Therefore, titania modified phosphate glasses may have future use as bone tissue engineering scaffolds. - Highlights: • This study investigated the role of titania on the biological response of phosphate glasses. • Incorporation of titania improved HOS cell attachment, viability and proliferation. • Titania modified glasses regulated osteoblastic cell differentiation. • Using osteogenic media had no significant effect on cell differentiation. • Titania modified glasses may have future use as bone tissue engineering scaffolds.

  2. Photocatalytic Activity of Reactively Sputtered Titania Coatings Deposited Using a Full Face Erosion Magnetron

    OpenAIRE

    Farahani, Nick; Kelly, Peter,; West, Glen; Hill, Claire; Vishnyakov, Vladimir

    2013-01-01

    Titanium dioxide (titania) is widely used as a photocatalyst for its moderate band gap, high photoactivity, recyclability, nontoxicity, low cost and its significant chemical stability. The anatase phase of titania is known to show the highest photocatalytic activity, however, the presence of this phase alone is not sufficient for sustained activity. In this study TiO2 coatings were deposited onto glass substrates by mid-frequency pulsed magnetron sputtering from metallic targets in reactive m...

  3. Synthesis and Characterization of Electrodeposited Nanocrystalline Nickel

    Institute of Scientific and Technical Information of China (English)

    DAI Pin-qiang; YU Hui, LI Qiang

    2004-01-01

    Nanocrystalline nickel was synthesize d by direct current electrodeposition from a modified Watts-type bath. X-ray diffraction and transmission electron microscope were used to characterize the microstructure of nickel deposits. The results show that nanocrytalline nickel with grain sizes in the range 20~50nm can be synthesized from saccharin-containing Watts-type baths with current density range 5~30A/dm2. There existed preferred orientation in the deposits and it changed progressively from a (200) fibre texture to a (111) (200) double fibre texture as saccharin concentration increased. The hardness of the deposits increased prominently as grain size decreased to nanometer range.

  4. Transparent nanocrystalline diamond coatings and devices

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Khan, Adam

    2017-08-22

    A method for coating a substrate comprises producing a plasma ball using a microwave plasma source in the presence of a mixture of gases. The plasma ball has a diameter. The plasma ball is disposed at a first distance from the substrate and the substrate is maintained at a first temperature. The plasma ball is maintained at the first distance from the substrate, and a diamond coating is deposited on the substrate. The diamond coating has a thickness. Furthermore, the diamond coating has an optical transparency of greater than about 80%. The diamond coating can include nanocrystalline diamond. The microwave plasma source can have a frequency of about 915 MHz.

  5. Tunable nonlinear absorption of hydrogenated nanocrystalline silicon.

    Science.gov (United States)

    Ma, Y J; Oh, J I; Zheng, D Q; Su, W A; Shen, W Z

    2011-09-01

    Nonlinear absorption (NLA) of hydrogenated nanocrystalline silicon (nc-Si:H) has been investigated through the open aperture Z-scan method for the photon energy of the incident irradiance slightly less than the bandgap of the sample. NLA responses have been observed to be highly sensitive to the wavelength and intensity of the incident irradiance as well as to the bandgap of the sample, indicating greatly tunable NLA of nc-Si:H. The band tail of nc-Si:H appears to play a crucial role in such NLA responses.

  6. Atomistic Mechanisms of Fatigue in Nanocrystalline Metals

    Science.gov (United States)

    Farkas, D.; Willemann, M.; Hyde, B.

    2005-04-01

    We investigate the mechanisms of fatigue behavior in nanocrystalline metals at the atomic scale using empirical force laws and molecular level simulations. A combination of molecular statics and molecular dynamics was used to deal with the time scale limitations of molecular dynamics. We show that the main atomistic mechanism of fatigue crack propagation in these materials is the formation of nanovoids ahead of the main crack. The results obtained for crack advance as a function of stress intensity amplitude are consistent with experimental studies and a Paris law exponent of about 2.

  7. LIGHT-WEIGHT NANOCRYSTALLINE HYDROGEN STORAGE MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    S. G. Sankar; B. Zande; R.T. Obermyer; S. Simizu

    2005-11-21

    During Phase I of this SBIR Program, Advanced Materials Corporation has addressed two key issues concerning hydrogen storage: 1. We have conducted preliminary studies on the effect of certain catalysts in modifying the hydrogen absorption characteristics of nanocrystalline magnesium. 2. We have also conducted proof-of-concept design and construction of a prototype instrument that would rapidly screen materials for hydrogen storage employing chemical combinatorial technique in combination with a Pressure-Composition Isotherm Measurement (PCI) instrument. 3. Preliminary results obtained in this study approach are described in this report.

  8. Nanocrystalline Ni-W coatings on copper

    Energy Technology Data Exchange (ETDEWEB)

    Panagopoulos, C.N., E-mail: chpanag@metal.ntua.gr [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780, Athens (Greece); Plainakis, G.D.; Lagaris, D.A. [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780, Athens (Greece)

    2011-04-15

    Nanocrystalline Ni-W coatings were produced on copper substrates with the aid of electrodeposition technique. The morphology, chemical composition and structure of the produced coatings were examined with the aid of scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS) and X-ray diffraction (XRD) techniques. The microhardness of alloy Ni-W coatings on copper substrate was also studied. The adhesion between the Ni-W coating, having W content 50 wt%, and the copper substrate, was also studied with a scratch testing apparatus. The scratch tests resulted in the coatings suffering an intensive brittle fracture and minor delamination.

  9. Synthesis and Characterization of Electrodeposited Nanocrystalline Nickel

    Institute of Scientific and Technical Information of China (English)

    DAIPin-qiang; YUHui; LIQiang

    2004-01-01

    Nanocrystalline nickel was synthesized by direct current electrodeposition from a modified Watts-type bath. X-ray diffraction and transmission electron microscope were used to characterize the microstructure of nickel deposits. The results show that nanocrytalline nickel with grain sizes in the range 20-50nm can be synthesized from saccharin-containing Watts-type baths with current density range 5-30A/dm2. There existed preferred orientation in the deposits and it changed progressively from a (200) fibre texture to a (111) (200) double fibre texture as saccharin concentration increased. The hardness of the deposits increased prominently as grain size decreased to nanometer range.

  10. Adsorption of diazinon and fenitrothion on nanocrystalline magnesium oxides

    Directory of Open Access Journals (Sweden)

    Mahsa Armaghan

    2017-01-01

    Full Text Available Nanocrystalline magnesium oxide was prepared by the sol–gel method from magnesium methoxide and characterized by Fourier transform infrared spectroscopy, thermal analysis, X-ray powder diffraction and transmission electron microscopy. Sol–gel derived nanocrystalline magnesium oxide along with a commercial nanocrystalline magnesium oxide was used as adsorbents to study the adsorption of two common, organophosphorous pesticides, diethoxy-[(2-isopropyl-6-methyl-4-pyrimidinyloxy]-thioxophosphorane (diazinon and dimethoxy-(3-methyl-4-nitrophenoxy-thioxophosphorane (fenitrothion. Adsorption of diazinon and fenitrothion on the sol–gel derived, and commercial nanocrystalline magnesium oxides was studied using UV–vis, FT-IR and 31P NMR spectroscopies. The effect of hydroxyl groups on edge/corner and flat panel of magnesium oxide in adsorption of diazinon and fenitrothion was investigated. The results showed that the adsorption of diazinon on the sol–gel derived nanocrystalline magnesium oxide is destructive whereas on commercial one is non-destructive. Commercial nanocrystalline magnesium oxide showed higher activity in the adsorption of fenitrothion than the sol–gel derived, and adsorptions on both nanocrystalline magnesium oxides are destructive.

  11. Hierarchical-structured anatase-titania/cellulose composite sheet with high photocatalytic performance and antibacterial activity.

    Science.gov (United States)

    Luo, Yan; Huang, Jianguo

    2015-02-02

    Bulk hierarchical anatase-titania/cellulose composite sheets were fabricated by subjecting an ultrathin titania gel film pre-deposited filter paper to a solvo-co-hydrothermal treatment by using titanium butoxide as the precursor to grow anatase-titania nanocrystallites on the cellulose nanofiber surfaces. The titanium butoxide specie is firstly absorbed onto the nanofibers of the cellulose substance through a solvothermal process, which was thereafter hydrolyzed and crystallized upon the subsequent hydrothermal treatment, leading to the formation of fine anatase-titania nanoparticles with sizes of 2-5 nm uniformly anchored on the cellulose nanofibers. The resulting anatase-titania/cellulose composite sheet shows a significant photocatalytic performance towards degradation of a methylene blue dye, and introduction of silver nanoparticles into the composite sheet yields an Ag-NP/anatase-titania/cellulose composite material possessing excellent antibacterial activity against both Gram-positive and Gram-negative bacteria. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Chirality of Single-Handed Twisted Titania Tubular Nanoribbons Prepared Through Sol-gel Transcription.

    Science.gov (United States)

    Wang, Sibing; Zhang, Chuanyong; Li, Yi; Li, Baozong; Yang, Yonggang

    2015-08-01

    Single-handed twisted titania tubular nanoribbons were prepared through sol-gel transcription using a pair of enantiomers. Handedness was controlled by that of the template. The obtained samples were characterized using field-emission electron microscopy, transmission electron microscopy, diffuse reflectance circular dichroism (DRCD), and X-ray diffraction. The DRCD spectra indicated that the titania nanotubes exhibit optical activity. Although the tubular structure was destroyed after being calcined at 700 °C for 2.0 h, DRCD signals were still identified. However, the DRCD signals disappeared after being calcined at 1000 °C for 2.0 h. The optical activity of titania was proposed to be due to chiral defects. Previous results showed that straight titania tubes could be used as asymmetric autocatalysts, indicating that titania exhibit chirality at the angstrom level. Herein, it was found that they also exhibit DRCD signals, indicating that there are no obvious relationships between morphology at the nano level and chirality at the angstrom level. The nanotube chirality should originate from the chiral defects on the nanotube inner surface. The Fourier transform infrared spectra indicated that the chirality of the titania was transferred from the gelators through the hydrogen bonding between N-H and Ti-OH.

  13. Hydrogen gas sensing feature of polyaniline/titania (rutile) nanocomposite at environmental conditions

    Energy Technology Data Exchange (ETDEWEB)

    Milani Moghaddam, Hossain, E-mail: hossainmilani@yahoo.com [Solid State Physics Department, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Nasirian, Shahruz [Solid State Physics Department, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Basic Sciences Department, Mazandaran University of Science and Technology, Babol (Iran, Islamic Republic of)

    2014-10-30

    Graphical abstract: - Highlights: • Polyaniline/titania (rutile) nanocomposite (TPNC) was synthesized by a chemical oxidative polymerization method. • Surface morphology and titania (rutile) wt% in TPNC sensors were significant factors for H{sub 2} gas sensing. • TPNC sensors could be used for H{sub 2} gas sensing at different R.H. humidity. • TPNC Sensors exhibited considerable sensitive, reversible and repeatable response to H{sub 2} gas at environmental conditions. - Abstract: The resistance-based sensors of polyaniline/titania (rutile) nanocomposite (TPNC) were prepared by spin coating technique onto an epoxy glass substrate with Cu-interdigited electrodes to study their hydrogen (H{sub 2}) gas sensing features. Our findings are that the change of the surface morphology, porosity and wt% of titania in TPNCs have a significant effect on H{sub 2} gas sensing of sensors. All of the sensors had a reproducibility response toward 0.8 vol% H{sub 2} gas at room temperature, air pressure and 50% relative humidity. A sensor with 40 wt% of titania nanoparticles had better response/recovery time and the response than other sensors. Moreover, H{sub 2} gas sensing mechanism of TPNC sensors based contact areas and the correlation of energy levels between PANI chains and the titania grains were studied.

  14. Molecularly imprinted titania nanoparticles for selective recognition and assay of uric acid

    Science.gov (United States)

    Mujahid, Adnan; Khan, Aimen Idrees; Afzal, Adeel; Hussain, Tajamal; Raza, Muhammad Hamid; Shah, Asma Tufail; uz Zaman, Waheed

    2015-06-01

    Molecularly imprinted titania nanoparticles are su ccessfully synthesized by sol-gel method for the selective recognition of uric acid. Atomic force microscopy is used to study the morphology of uric acid imprinted titania nanoparticles with diameter in the range of 100-150 nm. Scanning electron microscopy images of thick titania layer indicate the formation of fine network of titania nanoparticles with uniform distribution. Molecular imprinting of uric acid as well as its subsequent washing is confirmed by Fourier transformation infrared spectroscopy measurements. Uric acid rebinding studies reveal the recognition capability of imprinted particles in the range of 0.01-0.095 mmol, which is applicable in monitoring normal to elevated levels of uric acid in human blood. The optical shift (signal) of imprinted particles is six times higher in comparison with non-imprinted particles for the same concentration of uric acid. Imprinted titania particles have shown substantially reduced binding affinity toward interfering and structurally related substances, e.g. ascorbic acid and guanine. These results suggest the possible application of titania nanoparticles in uric acid recognition and quantification in blood serum.

  15. Solvothermal Synthesis of Visible Light Responsive Titania Nanocrystals at Moderate Temperature

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Visible light responsive nitrogen-doped titania nanocrystals were prepared by "Homogeneous Precipitation-Solvothermal Process" in TiCl3-hexamethylenetetramine (C6Hi2N4) mixed solution. The phase composition, crystallinity, microstructure and specific surface area of titania greatly changed depending on pH,solvent and temperature. The titania powders prepared in TiCl3-hexamethylenetetramine aqueous solutions at pH 1~6 and 190℃ for 2 h consisted of single phase of brookite and that prepared at pH 9 was single phase of rutile. On the other hand, the sample prepared in the presence of methanol at pH 9 consisted of single phase of anatase. All titania powders prepared in the present study were yellow and showed excellent visible light absorption property and photocatalytic ability for NO destruction under irradiation of the visible light (λ>510nm). The photocatalytic activity of the sample possessing similar specific surface area was in the order anatase > brookite > rutile. The photocatalytic activity of nitrogen doped titania under irradiation of visible light (λ>510 nm) slightly decreased with increasing calcination temperature up to 600℃ and then greatly decreased at 800 C. The visible light responsive photocatalytic activity of rutile titania nanoparticles could be improved by forming nanocomposite with layered tetratitanate possessing high specific surface area via a delamination-reassembly process of K2Ti4O9 combined with planetary ball-milling.

  16. Regularity control of porous anodic alumina and photodegradation activity of highly ordered titania nanostructures

    Institute of Scientific and Technical Information of China (English)

    LIU Xiang-zhi; XU Ming-xia; TIAN Yu-ming; SHANG Meng; ZHANG Ping

    2006-01-01

    A two-step anodizing process was used to prepare wide-range highly ordered porous anodic alumina membrane (PAA) in the electrolyte of oxalic acid. The effects of anodic voltage,anodizing time,size of aluminium foil and additives on the regularity of PAA membrane were also studied in the process of two-step anodization. The template method was combined with the sol-electrophoresis deposition and sol-gel method respectively to prepare highly ordered titania nanostructures. The diameter and length of the obtained nanostructures were determined by the pore size and depth of the PAA template. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the morphology and phase structure of the PAA template and the titania nanostructures. The results show that the anodizing time and the additive of ethanol have a great effect on the regularity of PAA template. This can be explained from the self-organized process and the current density theory. A theoretical model based on the self-organized process was established to discuss the formation mechanism of PAA template from the chemical perspective. The titania nanostructures prepared with this method has a high specific surface area. Furthermore,the photocatalytic activity of titania nanostructures on methyl orange were studied. Compared with ordinary titania membranes,the titania nanostructures synthesized with this method have higher photodegradation activity.

  17. Design and fabrication of heat resistant multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Thorne, J.M.; Knight, L.V.; Peterson, B.G.; Perkins, R.T.; Gray, K.J.

    1986-01-01

    Many promising applications of multilayer x-ray optical elements subject them to intense radiation. This paper discusses the selection of optimal pairs of materials to resist heat damage and presents simulations of multilayer performance under extreme heat loadings.

  18. Multilayer adsorption on fractal surfaces.

    Science.gov (United States)

    Vajda, Péter; Felinger, Attila

    2014-01-10

    Multilayer adsorption is often observed in liquid chromatography. The most frequently employed model for multilayer adsorption is the BET isotherm equation. In this study we introduce an interpretation of multilayer adsorption measured on liquid chromatographic stationary phases based on the fractal theory. The fractal BET isotherm model was successfully used to determine the apparent fractal dimension of the adsorbent surface. The nonlinear fitting of the fractal BET equation gives us the estimation of the adsorption equilibrium constants and the monolayer saturation capacity of the adsorbent as well. In our experiments, aniline and proline were used as test molecules on reversed phase and normal phase columns, respectively. Our results suggest an apparent fractal dimension 2.88-2.99 in the case of reversed phase adsorbents, in the contrast with a bare silica column with a fractal dimension of 2.54.

  19. Preparation and characterization of titania/silicone nanocomposite material

    Science.gov (United States)

    Shen, Y.; Wang, L.; Zhang, H.; Wu, T.; Pan, H. Y.

    2015-07-01

    The preparation and properties of high refractive index nanocomposite material were studied. The TiO2 nanoparticles were synthesized by sol-gel method using acetic acid as a chelating ligand. The nanoparticles were dispersed directly into the polymer matrix to prepare transparent high refractive index nanocomposite thin films. The refractive index of films will be enhanced with the increase of titania contents. The particles were characterized by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), and Fourier Transform Infrared Spectroscopy (FTIR), respectively. The results showed that all samples with different amounts of TiO2 exhibit good optical transparency. Furthermore, the pattern of the TiO2 NPs shows a pure anatase phases. From TEM image, the TiO2 has little agglomeration. The FT-IR spectrum indicated that acetate ions and titanium ions show good chelation.

  20. Benzaldehyde hydrogenation over titania-covered Pt powder

    Energy Technology Data Exchange (ETDEWEB)

    Vannice, M.A.; Poondi, D. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemical Engineering

    1998-08-15

    Titania when used as a support has been found to have a significant effect on the activity and selectivity of Pt during the hydrogenation of aldehydes and ketones. Turnover frequencies based on hydrogen adsorption sites are markedly enhanced, and rates per gram Pt (at similar dispersions) are also often increased. There are several explanations to account for this performance, at least partially. In an effort to determine the validity of these explanations, and hopefully to eliminate them as possibilities, a Pt powder was studied before and after the addition of varying amounts of TiO{sub 2} on its surface, and a physical mixture of this powder plus TiO{sub 2} was also examined and compared both to these catalysts and to Pt dispersed on TiO{sub 2}. The results follow.

  1. Separation of Iron Droplets From Titania Bearing Slag

    Institute of Scientific and Technical Information of China (English)

    WANG Ming-yu; LOU Tai-ping; ZHANG Li; SUI Zhi-tong

    2008-01-01

    Owing to smelting vanadium-titanium magnetite ore, the amount of iron entrainment in slag as droplets is far higher than that in conventional BF slag. However, the iron droplets can be easily settled by blowing air into the molten slag. The results show that more than 80% of iron droplets in titania bearing slag can be settled and separated after treatment. The temperature rise of molten slag during the oxidizing process and the decreased viscosity caused by the component change of slag as well as air stirring in slag both accelerate the iron droplets settling. The vanadium content in the settled iron droplets and the original iron droplets was obtained by chemical analysis. The possible reason for the increased vanadium in the settled iron droplets was discussed by thermodynamic principles.

  2. Thermally modified titania photocatalysts for phenol removal from water

    Directory of Open Access Journals (Sweden)

    Joanna Grzechulska-Damszel

    2006-01-01

    Full Text Available Two kinds of titanium dioxide were used as starting materials for thermal modification: Tytanpol A11 supplied by Chemical Factory “Police” S.A. (Poland and Degussa P25 supplied by Degussa AG (Germany. The photocatalytic activity of titania materials modified by thermal treatment was tested in the reaction of photocatalytic oxidation of phenol. It was found that the highest activity in the reaction of photocatalytic decomposition of phenol, in case of Tytanpol A11, shows the samples of material modified at temperatures of 700 and 750°C. These catalysts were more active than untreated A11, whereas materials modified at higher temperatures show lower activity. In the case of P25, all thermally treated materials were less active than the unmodified material. The photocatalyst samples were characterized by UV-Vis/DR, FTIR/DRS, and XRD methods.

  3. Formation of Surface Corrosion-Resistant Nanocrystalline Structures on Steel.

    Science.gov (United States)

    Nykyforchyn, Hryhoriy; Kyryliv, Volodymyr; Maksymiv, Olha; Slobodyan, Zvenomyra; Tsyrulnyk, Oleksandr

    2016-12-01

    Engineering materials with nanocrystalline structure could be exploited under simultaneous action of mechanical loading and corrosion environments; therefore, their corrosion resistance is important. Surface nanocrystalline structure was generated on middle carbon steels by severe plastic deformation using the method of mechanical pulse friction treatment. This treatment additionally includes high temperature phase transformation and alloying. Using a complex of the corrosive, electrochemical and physical investigations, it was established that nanocrystalline structures can be characterized by lower or increased corrosion resistance in comparison with the reference material. It is caused by the action of two confronting factors: arising energy level and anticorrosive alloying of the surface layer.

  4. Microstructure and Performances of Nanocrystalline Zinc-nickel Alloy Coatings

    Institute of Scientific and Technical Information of China (English)

    LI Guang-yu; LIAN Jian-she; NIU Li-yuan; JIANG Zhong-hao

    2004-01-01

    Nanocrystalline zinc-nickel alloy coatings were deposited from an alkaline zincate bath contained an organic additive that can reduce polarization and a complexing agent. SEM and TEM observations and XRD analysis were performed to examine the microstructure and phase composition of the coatings. The nickel content in deposits is 12.0~14.7% and the coating is consisted of single nanocrystalline γ-phase structure (Ni5Zn21), with grain average grain size about 15nm. The nanocrystalline zinc-nickel alloy coatings have better corrosion resistance, less brittleness and higher microhardness than the conventional zinc coatings.

  5. Si/Nanocrystalline Diamond Film Heterojunction Diodes Preparation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    With electron assisted hot filament chemical vapor deposition technology, nanocrystalline diamond films were deposited on polished n-(100)Si wafer surface. The deposited films were characterized and observed by Raman spectrum, X-ray diffraction, semiconductor characterization system and Hall effective measurement system. The results show that with EA-HFCVD, not only an undoped nanocrystalline diamond films with high-conductivity (p-type semiconducting) but also a p-n heterojunction diode between the nanocrystalline diamond films and n-Si substrate is fabricated successfully. The p-n heterojunction has smaller forward resistance and bigger positive resistance. The p-n junction effective is evident.

  6. Nanocrystalline cerium oxide materials for solid fuel cell systems

    Science.gov (United States)

    Brinkman, Kyle S

    2015-05-05

    Disclosed are solid fuel cells, including solid oxide fuel cells and PEM fuel cells that include nanocrystalline cerium oxide materials as a component of the fuel cells. A solid oxide fuel cell can include nanocrystalline cerium oxide as a cathode component and microcrystalline cerium oxide as an electrolyte component, which can prevent mechanical failure and interdiffusion common in other fuel cells. A solid oxide fuel cell can also include nanocrystalline cerium oxide in the anode. A PEM fuel cell can include cerium oxide as a catalyst support in the cathode and optionally also in the anode.

  7. Sensitization of Xanthophylls-Chlorophyllin Mixtures on Titania Solar Cells

    Directory of Open Access Journals (Sweden)

    Indriana Kartini

    2015-03-01

    Full Text Available Co-sensitization of natural dyes on TiO2 for dye-sensitized solar cell (DSSC was proposed between chlorophyllin (C and xanthophylls (X at various volume ratios of C/X. Chlorophyllin is chlorophyll derivative providing -COOH groups essential for binding to TiO2. The chlorophyll was extracted from dried spinach (amaranthus viridis leaves in a mixture of methanol-acetone (70%:30%. Chlorophyll extract dye was obtained after partition of the crude extracts in diethyl ether solution. Then, it was hydrolyzed under alkaline condition to get chlorophyllin. Xanthophyll was extracted from fresh petal of chrysanthemum (chrysanthemum indicum flowers. Blending of chlorophyllin and xanthophyll was carried out at various volume ratios of C to X (1:0, 5:1, 1:1, 1:5, 0:1. Titania solar cells were constructed in sandwich system of conducting glass-titania/dyes as the photoanode and conducting glass-platinum as the photocathode. Electrolyte solution containing I-/I3- was inserted between the electrodes by capillary action. All dye extracts and blending solutions were analyzed by UV-Vis spectrophotometer. It is shown that the absorption spectra of blending dyes are complimentary in the visible region resulted in a panchromatic response of the dyes. From the cyclic voltammogram of the dyes and blended-dyes, it is found that the energy level of xanthophyll is the lowest. The I-V test at 100 mw/cm2 irradiation confirmed that the energy conversion efficiency (h of the blended dyes of xanthophyll and chlorophyllin-sensitized solar cell resulted in significant improvement than those of the single dye. Beneficially, the mixed dyes can be adsorbed from solution blend using single dipping step.

  8. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    Science.gov (United States)

    Gao, Jinjin; Zhao, Chengjian; Zhou, Jingfang; Li, Chunxia; Shao, Yiran; Shi, Chao; Zhu, Yingchun

    2015-11-01

    Rutile titania (TiO2) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO2 coatings. In the study, titania-nanosilver (TiO2/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO2 powders containing 1-10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO2/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO2/Ag coatings and no crystalline changed happened in the TiO2 structure. The reduction ratios on the TiO2/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO2/Ag coatings with 100-1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO2/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the antibacterial properties of TiO2/Ag coatings were discussed with grain size and the content of silver as well as the microstructure of the coatings.

  9. Nanocrystalline magnetic materials obtained by flash annealing

    Directory of Open Access Journals (Sweden)

    R.K. Murakami

    1999-04-01

    Full Text Available The aim of the present work was to produce enhanced-remanence nanocrystalline magnetic material by crystallizing amorphous or partially amorphous Pr4.5Fe77B18.5 alloys by the flash annealing process, also known as the dc-Joule heating process, and to determine the optimal conditions for obtaining good magnetic coupling between the magnetic phases present in this material. Ribbons of Pr4.5Fe77B18.5 were produced by melt spinning and then annealed for 10-30 s at temperatures 500 - 640 °C by passing current through the sample to develop the enhanced-remanence nanocrystalline magnetic material. These materials were studied by X-ray diffraction, differential thermal analysis and magnetic measurements. Coercivity increases of up to 15% were systematically observed in relation to furnace-annealed material. Two different samples were carefully examined: (i a sample annealed at 600 °C which showed the highest coercive field Hc and remanence ratio Mr/Ms and (ii a sample annealed at 520 °C which showed phase separation in the second quadrant demagnetization curve. Our results are in agreement with other studies which show that flash annealing improves the magnetic properties of some amorphous ferromagnetic ribbons.

  10. Bulk nanocrystalline Al prepared by cryomilling

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Bulk nanocrystalline Al was fabricated by mechanically milling at cryogenic temperature (cryomilling) and then by hot pressing in vacuum. By using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), the microstructure evolution of the material during cryomilling and consolidation was investigated. With increasing the milling time, the grain size decreased sharply and reduced to 42 nm when cryomilled for 12 h. The grains had grown up, and the columnar grain was formed under the hot pressing and extrusion compared with the cryomilled powders. The grain size of as-extruded specimen was approximately 300-500 nm. The reason of high thermal stability of this bulk was attributed primarily to the Zener pinning from the grain boundary of the AlN arising from cryomilling and the solute drag of the impurity. Tensile tests show that the strength of nanocrystalline Al is enhanced with decreasing grain size. The ultimate tensile strength and tensile elongation were 173 MPa and 17.5%, respectively. It appears that the measured high strength in the cryomilled Al is related to a grain-size effect, dispersion strengthening, and dislocation strengthening.

  11. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    ZHU ZengWei; ZHU Di; QU NingSong

    2008-01-01

    A new mechanical electrodeposition technology was proposed,and nanocrystal-line nickel deposit with bright and smooth surface was prepared in the bath without any additive agents.Unlike traditional methods,the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing.Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits,pinholes and nodules.Furthermore,comparing with the deposit prepared by tradi-tional methods,the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm.Every diffraction peak's intensity of the deposit was reduced,the preferential orientation degree of (200) decreased and those of (111) and (220) increased.The microhardness notably increased.The magnetic properties were also changed with decreased saturation magnetization and increased coercive force.It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.Key.words:electrodeposition,electroforming,hard particle,nanocrystalline,bright nickel deposits prepared by this technology.

  12. Microhardness studies of nanocrystalline lead molybdate

    Energy Technology Data Exchange (ETDEWEB)

    Anandakumar, V.M. [Department of Physics, University of Kerala, Kariavattom P.O., Thiruvananthapuram 695581 (India); Department of Physics, Mahatma Gandhi College, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Abdul Khadar, M., E-mail: mabdulkhadar@rediffmail.com [Department of Physics, University of Kerala, Kariavattom P.O., Thiruvananthapuram 695581 (India); Centre for Nanoscience and Nanotechnology, University of Kerala, Kariavattom P.O., Thiruvananthapuram 695581 (India)

    2009-08-30

    Nanocrystalline lead molybdate (PbMoO{sub 4}) of four different grain sizes were synthesized through chemical precipitation technique and the grain sizes and crystal structure are determined using the broadening of X-ray diffraction patterns and transmission electron microscopy. The microhardness of nanocrystalline lead molybdate (PbMoO{sub 4}) with different grain sizes were measured using a Vicker's microhardness tester for various applied loads ranging from 0.049 to 1.96 N. The microhardness values showed significant indentation size effect at low indentation loads. The proportional specimen resistance model put forward by Li and Bradt and energy balance model put forward by Gong and Li were used to analyze the behaviour of measured microhardness values under different indentation loads. The microhardness data obtained for samples of different grain sizes showed grain size dependent strengthening obeying normal Hall-Petch relation. The dependence of compacting pressure and annealing temperature on microhardness of the nanostructured sample with grain size of {approx}18 nm were also studied. The samples showed significant increase in microhardness values as the compacting pressure and annealing time were increased. The variation of microhardness of the material with pressure of pelletization and annealing time are discussed in the light of change of pore size distribution of the samples.

  13. Design, Modeling and Optimization of a Piezoelectric Pressure Sensor based on a Thin-Film PZT Membrane Containing Nanocrystalline Powders

    Directory of Open Access Journals (Sweden)

    Vahid MOHAMMADI

    2009-11-01

    Full Text Available In this paper fabrication of a 0-3 ceramic/ceramic composite lead zirconate titanate, Pb(Zr0.52Ti0.48O3 thin film has been presented and then a pressure sensor based on multilayer thin-film PZT diaphragm contain of Lead Zirconate Titanate nanocrystalline powders was designed, modeled and optimized. Dynamics characteristics of this multilayer diaphragm have been investigated by ANSYS® FE software. By this simulation the effective parameters of the multilayer PZT diaphragm for improving the performance of a pressure sensor in different ranges of pressure are optimized. The optimized thickness ratio of PZT layer to SiO2 was given in the paper to obtain the maximum deflection of the multilayer thin-film PZT diaphragm. A 0-3 ceramic/ceramic composite lead zirconate titanate, Pb(Zr0.52Ti0.48O3 film has been developed to fabricate the pressure sensor by a hybrid sol gel process. PZT nanopowders fabricated via conventional sol gel method and uniformly dispersed in PZT precursor solution by an attrition mill. XRD analysis shows that perovskite structure would be formed due to the presence of a significant amount of ceramic nanopowders. This texture has a good effect on piezoelectric properties of perovskite structure. The film forms a strongly bonded network and less shrinkage occurs, so the films do not crack during process. Also the aspect ratio through this process would be increased. SEM micrographs indicated that PZT films were uniform, crack free and have a composite microstructure and a piezoelectric coefficient d31 of -40 pC.N-1 and d33 ranged from 50pm.N-1 to 60pm.N-1.

  14. Corrosion investigation of multilayered ceramics and experimental nickel alloys in SCWO process environments

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, K.M.; Mizia, R.

    1995-02-01

    A corrosion investigation was done at MODAR, Inc., using a supercritical water oxidation (SCWO) vessel reactor. Several types of multilayered ceramic rings and experimental nickel alloy coupons were exposed to a chlorinated cutting oil TrimSol, in the SCWO process. A corrosion casing was designed and mounted in the vessel reactor with precautions to minimize chances of degrading the integrity of the pressure vessel. Fifteen of the ceramic coated rings were stacked vertically in the casing at one time for each test. There was a total of 36 rings. The rings were in groupings of three rings that formed five sections. Each section saw a different SCWO environment, ranging from 650 to 300{degrees}C. The metal coupons were mounted on horizontal threaded holders welded to a vertical rod attached to the casing cover in order to hang down the middle of the casing. The experimental nickel alloys performed better than the baseline nickel alloys. A titania multilayered ceramic system sprayed onto a titanium ring remained intact after 120-180 hours of exposure. This is the longest time any coating system has withstood such an environment without significant loss.

  15. The liquid-liquid interface as a medium to generate nanocrystalline films of inorganic materials.

    Science.gov (United States)

    Rao, C N R; Kalyanikutty, K P

    2008-04-01

    been examined. Interfacial rheological studies show that the nanocrystalline film of Ag nanoparticles, the single-crystalline CuS film, and the multilayered CdS film exhibit a viscoelastic behavior strongly reminiscent of soft-glassy systems. Though both CuS and CdS films exhibit a finite yield stress under steady shear, the CdS films are found to rupture at high shear rates. An important advantage of the study of materials formed at the liquid-liquid interface is that it provides a means to investigate the interface itself. In addition, it enables one to obtain substrate-free single-crystalline films of materials.

  16. RHEOLOGICAL ASPECTS OF MULTILAYER MATERIALS

    Directory of Open Access Journals (Sweden)

    V. V. Artemchuk

    2010-11-01

    Full Text Available The issues related to renewal of worn-out parts of a rolling stock with the layered coatings are considered in the article. In developing a mathematical model of wearing a multilayer material as an object of rheology certain assumptions, which enable using the methods of mechanics and mechanics of continuous medium, are done.

  17. Multilayer Controller for Outdoor Vehicle

    DEFF Research Database (Denmark)

    Reske-Nielsen, Anders; Mejnertsen, Asbjørn; Andersen, Nils Axel

    2006-01-01

    A full software and hardware solution has been designed, implemented and tested for control of a small agricultural automatic tractor. The objective was to realise a user-friendly, multi-layer controller architecture for an outdoor platform. The collaborative research work was done as a part...

  18. New developments in Ni/Ti multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, I.; Hoghoj, P. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    It is now 20 years since super-mirrors were first used as a neutron optical element. Since then the field of multilayer neutron-optics has matured with multilayers finding their way to application in many neutron scattering instruments. However, there is still room for progress in terms of multilayer quality, performance and application. Along with work on multilayers for neutron polarisation Ni/Ti super-mirrors have been optimised. The state-of-the-art Ni/Ti super-mirror performance and the results obtained in two neutron-optics applications of Ni/Ti multilayers are presented. (author).

  19. Martensite and bainite in nanocrystalline steels: understanding, design and applications

    Directory of Open Access Journals (Sweden)

    Caballero Francisca G.

    2015-01-01

    Full Text Available There are major difficulties in creating novel nanocrystalline structures that have a combination of properties appropriate for large scale applications. An important requirement is to be able to manufacture nanocrystalline components which are large in all dimensions on their macroscale whilst retaining their nanostructure. In addition, the material concerned must be cheap to produce if it is not to be limited to niche applications. Severe plastic deformation has not succeeded in this respect since grain growth cannot effectively be suppressed during consolidation processes. Therefore, processing bulk nanocrystalline materials for structural applications still poses a big challenge, particularly in achieving an industrially viable process. Here we describe various processing strategies and alloy developments currently being explored in the modern steel industry that have the potential to create extremely strong and affordable nanocrystalline engineering steels.

  20. High Temperature Stable Nanocrystalline SiGe Thermoelectric Material

    Science.gov (United States)

    Yang, Sherwin (Inventor); Matejczyk, Daniel Edward (Inventor); Determan, William (Inventor)

    2013-01-01

    A method of forming a nanocomposite thermoelectric material having microstructural stability at temperatures greater than 1000 C. The method includes creating nanocrystalline powder by cryomilling. The method is particularly useful in forming SiGe alloy powder.

  1. Molecular dynamics simulation of thermal stability of nanocrystalline vanadium

    Institute of Scientific and Technical Information of China (English)

    WEI; Mingzhi; XIAO; Shifang; YUAN; Xiaojian; HU; Wangyu

    2006-01-01

    The microstructure and thermal stability of nanocrystalline vanadium with an average grain size ranging from 2.86 to 7.50 nm are calculated by means of the analytic embedded-atom method and molecular dynamics. The grain boundary and nanocrystalline grain atoms are differentiated by the common neighbor analysis method. The results indicate that the fraction of grain boundary increases with the grain size decreasing, and the mean energy of atoms is higher than that of coarse crystals. The thermal-stable temperatures of nanocrystalline vanadium are determined from the evolution of atomic energy, fraction of grain boundary and radial distribution function. It is shown that the stable temperature decreases obviously with the grain size decreasing. In addition the reasons which cause the grain growth of nanocrystalline vanadium are discussed.

  2. Silver decorated titanate/titania nanostructures for efficient solar driven photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Dangguo [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Heterogeneous Catalysis Technology, Institute of Chemical and Engineering Sciences, 1 Pesek Road, Singapore 627833 (Singapore); Ho, Weng Chye Jeffrey; Tang Yuxin; Tay Qiuling; Lai Yuekun [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Highfield, James George, E-mail: james_highfield@ices.a-star.edu.sg [Heterogeneous Catalysis Technology, Institute of Chemical and Engineering Sciences, 1 Pesek Road, Singapore 627833 (Singapore); Chen Zhong, E-mail: aszchen@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2012-05-15

    Photocatalysis has attracted significant interest to solve both the energy crisis and effectively combat environmental contamination. However, as the most widely used photocatalyst, titania (TiO{sub 2}) suffers from inefficient utilization of solar energy due to its wide band gap. In the present paper, we describe a method to extend the absorption edge of photocatalyst to visible region by the surface plasmon effect of silver. Silver ions are photo-reduced onto the surface of titanate nanotubes, which are synthesized by a conventional hydrothermal method. The as-synthesized Ag/titanate composite is transformed into Ag/titania nanoparticles by annealing at different temperatures. It is found that the interaction of Ag nanoparticles with the supports (titanate/titania) plays a key role for the visible light activity. The samples annealed at low temperature (<350 Degree-Sign C) do not show significant activity under our conditions, while the one annealed at 450 Degree-Sign C shows fast-degradation of methyl orange (MO) under visible light irradiation. The detailed mechanisms are also discussed. - Graphical abstract: Silver nanoparticles decorated titanate/titania as visible light active photocatalysts: silver nanoparticles could be excited by visible light due to its surface plasmon effect and excited electrons could be transferred to the conduction band of the semiconductor, where the reduction process occurs. Highlights: Black-Right-Pointing-Pointer Uniform Ag nanoparticles are photo-reduced onto titanate and titania nanostructures. Black-Right-Pointing-Pointer Titania crystal is formed by annealing hydrogen titanate at different temperatures. Black-Right-Pointing-Pointer Best visible-light activity is achieved by Ag-loaded titania annealed at 450 Degree-Sign C. Black-Right-Pointing-Pointer The visible light activity is attributed to the surface plasmonic resonance effect.

  3. Martensite and bainite in nanocrystalline steels: understanding, design and applications

    OpenAIRE

    Caballero Francisca G.

    2015-01-01

    There are major difficulties in creating novel nanocrystalline structures that have a combination of properties appropriate for large scale applications. An important requirement is to be able to manufacture nanocrystalline components which are large in all dimensions on their macroscale whilst retaining their nanostructure. In addition, the material concerned must be cheap to produce if it is not to be limited to niche applications. Severe plastic deformation has not succeeded in this respec...

  4. A New Attempt to Obtain Bulk Nanocrystalline Steel

    Institute of Scientific and Technical Information of China (English)

    Shengjie Yao; Linxiu Du; Xianghua Liu; Guodong Wang

    2009-01-01

    Bulk nanocrystalline steel sample was obtained in laboratory through refining of austenite grains and controlled rolling. Transmission electron microscopy micrographs show that some textures are evolved in the process of the treatment and two typical carbides are classified according to their size and location. The tensile strength of the nanocrystalline sample is obviously lower than conventional consideration, and scanning electron microscopy observation shows that the existence of the first type of carbide is considered as the main reason for the failure.

  5. High Pressure X-Ray Diffraction Studies on Nanocrystalline Materials

    Science.gov (United States)

    Palosz, B.; Stelmakh, S.; Grzanka, E.; Gierlotka, S.; Pielaszek, R.; Bismayer, U.; Werner, S.; Palosz, W.

    2003-01-01

    Application of in situ high pressure powder diffraction technique for examination of specific structural properties of nanocrystals based on the experimental data of SiC nanocrystalline powders of 2 to 30 nrn diameter in diameter is presented. Limitations and capabilities of the experimental techniques themselves and methods of diffraction data elaboration applied to nanocrystals with very small dimensions (nanocrystalline powders under pressure. We offer a tentative interpretation of the distribution of macro- and micro-strains in nanoparticles of different grain size.

  6. Reversal of exchange bias in nanocrystalline antiferromagnetic-ferromagnetic bilayers

    CERN Document Server

    Prados, C; Hernando, A; Montone, A

    2002-01-01

    The sign of the exchange bias in field cooled nanocrystalline antiferromagnetic-ferromagnetic bilayers (Co-O and Ni-O/permalloy) is reversed at temperatures approaching the antiferromagnetic (AFM) blocking temperature. A similar phenomenon is observed after magnetic training processes at similar temperatures. These effects can be explained assuming that the boundaries of nanocrystalline grains in AFM layers exhibit lower transition temperatures than grain cores.

  7. Electrochemistry of Inorganic Nanocrystalline Electrode Materials for Lithium Batteries

    Directory of Open Access Journals (Sweden)

    C. W. Kwon

    2003-01-01

    much different from that of traditional crystalline ones because of their significant ‘surface effects’. In connection with that, the nanocrystalline cathode materials are reported to have an enhanced electrochemical activity when the first significative electrochemical step is insertion of Li ions (discharge process. The “electrochemical grafting” concept will be given as a plausible explanation. As illustrative examples, electrochemical behaviors of nanocrystalline manganese oxydes are presented.

  8. Voronoi Based Nanocrystalline Generation Algorithm for Atomistic Simulations

    Science.gov (United States)

    2016-12-22

    with implementing ran- domly dispersed Voronoi tessellation algorithms for nanocrystalline construction is 1 Approved for public release; distribution...generate a list of grain centers that are populated with seeds —spherical groups of atoms extracted from a reference file. This method uses a single...the methods and code used to generate a nanocrystalline structure with a single reference file for seed extraction. Some of the code segments detailed

  9. Defect and electrical properties of nanocrystalline tungsten trioxide

    Institute of Scientific and Technical Information of China (English)

    Yang Xin-Sheng; Wang Yu; Dong Liang; Qi Li-Zhen; Zhang Feng

    2004-01-01

    Nanocrystalline tungsten trioxide particles were prepared by a wet-chemical method. Transmission electron microscope (TEM) analysis shows that the average grain size is about 15nm. The oxygen deficiency of nanometre-sized sample is higher than that of ordinary tungsten trioxide. The electric conductivity increases because of high oxygen deficiency. Ironic relaxation polarization and crystallographic shear (CS) planes theory were used to explain the unusual dielectric characteristic of nanocrystalline tungsten trioxide.

  10. Nanocrystalline La2Mo2O9 and Its Characterization

    Institute of Scientific and Technical Information of China (English)

    Li Qin; Xia Tian; Li Jiayan; Liu Xiangdong; Ma Xianfeng; Meng Jian; Cao Xueqiang

    2004-01-01

    In this work, both the thermal expansion and electrical conductivity of nanocrystalline La2Mo2O9 were studied.The nanocrystalline powder of La2Mo2O9 was obtained by sol-gel method, and with the help of SHP (superhigh pressure)up to 4.5 × 104 atm at 700 ℃ for a short time, and the nanocrystalline powder was densified without obvious particle size growth. The electrical conductivity of nanocrystalline La2Mo2O9 was one orderof magnitude lower than that of the microcrystalline sample at the same temperature. Owing to the phase transition, the microcrystalline La2Mo2O9 has an abrupt increase of thermal expansion with a peak value of 48 × 10-6 K-1 at 556 ℃. For the nanocrystalline material, the peak value increases to 112 × 10-6 K-1 at 520 ℃. On the other hand, above 600 ℃ the significant growth of particle size of the nanocrystalline La2Mo2O9 was observed, accompanying by a tremendous increase of thermal expansion with a peak value of third higher than that of La2Mo2O9.

  11. Magnetic Properties of Grain Boundaries of Nanocrystalline Ni and of Ni Precipitates in Nanocrystalline NiCu Alloys

    Science.gov (United States)

    Wolf, H.; Guan, Z.; Li, X.; Wichert, Th.

    2001-11-01

    Perturbed γγ-angular correlation spectroscopy (PAC) was used to investigate nanocrystalline Ni and NiCu alloys, which are prepared by pulsed electrodeposition (PED). Using diffusion for doping nanocrystalline Ni with 111In four different ordered grain boundary structures are observed, which are characterized by unique electric field gradients. The incorporation of 111In on substitutional bulk sites of Ni is caused by moving grain boundaries below 1000 K and by volume diffusion above 1000 K. The nanocrystalline NiCu alloys prepared by PED are microscopically inhomogeneous as observed by PAC. In contrast, this inhomogeneity cannot be detected by X-ray diffraction. The influence of the temperature of the electrolyte, the current density during deposition, and the optional addition of saccharin to the electrolyte on the homogeneity of nanocrystalline NiCu alloys was investigated.

  12. Stabilization of mesoporous nanocrystalline zirconia with Laponite

    Institute of Scientific and Technical Information of China (English)

    LIU Xinmei; YAN Zifeng; LU Gaoqing

    2005-01-01

    The mesoporous nanocrystalline zircoina was synthesized via solid state reaction--structure directing method in the presence of Laponite. The introduction of Laponite renders the higher thermal stability and lamellar track to the zirconia. Laponite acts as inhibitor for crystal growth and also hard template for the mesostructure. The role of Laponite is attributed to the interaction between the zirconia precursors and the nano-platelets of Laponite via the bridge of hydrophilic segments of surfactant. It results in the formation of Zr-O-Mg-O-Si frameworks in the direction of Laponite layer with the condensation of frameworks during the calcination process, which contributes the higher stability and lamellar structure to the nano-sized zirconia samples.

  13. Reinforced plastics and aerogels by nanocrystalline cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Alfred C. W.; Lam, Edmond; Chong, Jonathan; Hrapovic, Sabahudin; Luong, John H. T., E-mail: john.luong@cnrc-nrc.gc.ca [National Research Council Canada (Canada)

    2013-05-15

    Nanocrystalline cellulose (NCC), a rigid rod-like nanoscale material, can be produced from cellulosic biomass in powder, liquid, or gel forms by acid and chemical hydrolysis. Owing to its unique and exceptional physicochemical properties, the incorporation of a small amount of NCC into plastic enhances the mechanical strength of the latter by several orders of magnitudes. Carbohydrate-based NCC poses no serious environmental concerns, providing further impetus for the development and applications of this green and renewable biomaterial to fabricate lightweight and biodegradable composites and aerogels. Surface functionalization of NCC remains the main focus of NCC research to tailor its properties for dispersion in hydrophilic or hydrophobic media. It is of uttermost importance to develop tools and protocols for imaging of NCC in a complex matrix and quantify its reinforcement effect.

  14. Reinforced plastics and aerogels by nanocrystalline cellulose

    Science.gov (United States)

    Leung, Alfred C. W.; Lam, Edmond; Chong, Jonathan; Hrapovic, Sabahudin; Luong, John H. T.

    2013-05-01

    Nanocrystalline cellulose (NCC), a rigid rod-like nanoscale material, can be produced from cellulosic biomass in powder, liquid, or gel forms by acid and chemical hydrolysis. Owing to its unique and exceptional physicochemical properties, the incorporation of a small amount of NCC into plastic enhances the mechanical strength of the latter by several orders of magnitudes. Carbohydrate-based NCC poses no serious environmental concerns, providing further impetus for the development and applications of this green and renewable biomaterial to fabricate lightweight and biodegradable composites and aerogels. Surface functionalization of NCC remains the main focus of NCC research to tailor its properties for dispersion in hydrophilic or hydrophobic media. It is of uttermost importance to develop tools and protocols for imaging of NCC in a complex matrix and quantify its reinforcement effect.

  15. Nanocrystalline Steels’ Resistance to Hydrogen Embrittlement

    Directory of Open Access Journals (Sweden)

    Skołek E.

    2015-04-01

    Full Text Available The aim of this study is to determine the susceptibility to hydrogen embrittlement in X37CrMoV5-1 steel with two different microstructures: a nanocrystalline carbide-free bainite and tempered martensite. The nanobainitic structure was obtained by austempering at the bainitic transformation zone. It was found, that after hydrogen charging, both kinds of microstructure exhibit increased yield strength and strong decrease in ductility. It has been however shown that the resistance to hydrogen embrittlement of X37CrMoV5-1 steel with nanobainitic structure is higher as compared to the tempered martensite. After hydrogen charging the ductility of austempered steel is slightly higher than in case of quenched and tempered (Q&T steel. This effect was interpreted as a result of phase composition formed after different heat treatments.

  16. Synthesis and characterization of nanocrystalline zinc ferrite

    DEFF Research Database (Denmark)

    Jiang, J.S.; Yang, X.L.; Gao, L.

    1999-01-01

    Nanocrystalline zinc ferrite powders with a partially inverted spinel structure were synthesized by high-energy ball milling in a closed container at ambient temperature from a mixture of alpha-Fe2O3 and ZnO crystalline powders in equimolar ratio. From low-temperature and in-field Mossbauer...... measurements it is revealed that ZnFe2O4 particles prepared are in superparamagnetic state at ambient temperature. A doublet with an average quadrupole splitting of 0.8 nm/s is observed for the as-milled sample at 295 K, which is much larger than that for bulk ZnFe2O4 prepared by traditional ceramic method...... and that for ultrafine ZnFe2O4 particles prepared by the co-precipitation method. This indicates larger structural defects in the nanometer-sized ZnFe2O4 particles prepared by high-energy ball milling....

  17. An ecotoxicological characterization of nanocrystalline cellulose (NCC).

    Science.gov (United States)

    Kovacs, Tibor; Naish, Valerie; O'Connor, Brian; Blaise, Christian; Gagné, Francois; Hall, Lauren; Trudeau, Vance; Martel, Pierre

    2010-09-01

    The pulp and paper industry in Canada is developing technology for the production and use of nanocrystalline cellulose (NCC). A key component of the developmental work is an assessment of potential environmental risks. Towards this goal, NCC samples as well as carboxyl methyl cellulose (CMC), a surrogate of the parent cellulosic material, were subjected to an ecotoxicological evaluation. This involved toxicity tests with rainbow trout hepatocytes and nine aquatic species. The hepatocytes were most sensitive (EC20s between 10 and 200 mg/l) to NCC, although neither NCC nor CMC caused genotoxicity. In tests with the nine species, NCC affected the reproduction of the fathead minnow at (IC25) 0.29 g/l, but no other effects on endpoints such as survival and growth occurred in the other species at concentrations below 1 g/l, which was comparable to CMC. Based on this ecotoxicological characterization, NCC was found to have low toxicity potential and environmental risk.

  18. Functionalization of nanocrystalline diamond films with phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Petkov, Christo [Institute of Nanostructure Technologies and Analytics (INA), Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel (Germany); Reintanz, Philipp M. [Institute of Chemistry, Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel (Germany); Kulisch, Wilhelm [Institute of Nanostructure Technologies and Analytics (INA), Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel (Germany); Degenhardt, Anna Katharina [Institute of Chemistry, Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel (Germany); Weidner, Tobias [Max Planck Institute for Polymer Research, Mainz (Germany); Baio, Joe E. [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR (United States); Merz, Rolf; Kopnarski, Michael [Institut für Oberflächen- und Schichtanalytik (IFOS), Kaiserslautern (Germany); Siemeling, Ulrich [Institute of Chemistry, Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel (Germany); Reithmaier, Johann Peter [Institute of Nanostructure Technologies and Analytics (INA), Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel (Germany); Popov, Cyril, E-mail: popov@ina.uni-kassel.de [Institute of Nanostructure Technologies and Analytics (INA), Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel (Germany)

    2016-08-30

    Highlights: • Grafting of phthalocyanines on nanocrystalline diamond films with different terminations. • Pc with different central atoms and side chains synthesized and characterized. • Attachment of Pc on H- and O-terminated NCD studied by XPS and NEXAFS spectroscopy. • Orientation order of phthalocyanine molecules on NCD surface. - Abstract: Phthalocyanine (Pc) derivatives containing different central metal atoms (Mn, Cu, Ti) and different peripheral chains were synthesized and comprehensively characterized. Their interaction with nanocrystalline diamond (NCD) films, as-grown by hot-filament chemical vapor deposition or after their modification with oxygen plasma to exchange the hydrogen termination with oxygen-containing groups, was studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The elemental composition as determined by XPS showed that the Pc were grafted on both as-grown and O-terminated NCD. Mn, Cu and Ti were detected together with N stemming from the Pc ring and S in case of the Ti-Pc from the peripheral ligands. The results for the elemental surface composition and the detailed study of the N 1s, S 2p and O 1s core spectra revealed that Ti-Pc grafted better on as-grown NCD but Cu-Pc and Mn-Pc on O-terminated films. Samples of Mn-Pc on as-grown and O-terminated NCD were further investigated by NEXAFS spectroscopy. The results showed ordering of the grafted molecules, laying flat on the H-terminated NCD surface while only the macrocycles were oriented parallel to the O-terminated surface with the peripheral chains perpendicular to it.

  19. Preparation and characterization of porous titania-grafted poly(styrene-divinylbenzene)/maleic anhydride nanocomposite microspheres

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Mesoporous titania-grafted poly(styrene-divinylbenzene)/maleic anhydride [P(St-DVB)/MA] nanocomposite microspheres were prepared by an open ring reaction method.The titania nanoparticles were first modified by attachment of amino groups to their surface to prevent particle aggregation,and to allow the nanoparticles to covalently bond the polymer microspheres,the surface of which was modified by attachment of MA functional groups to enable the polymer to retain their porous structures and to react with the amino groups on the surface of the titania particles.The porous nanocomposite microspheres were detected by FTIR,SEM,TEM,XRD and UV-Vis spectrophotometry.The results indicated that the nanocomposite microspheres were composed of nanosized titania uniformly distributed on the surface,and exhibited better UV absorbing property than pure polymer microspheres or unmodified titania.Furthermore,compared with pure porous polymer microspheres,the nanocomposite microspheres showed more efficient UV protection and slow release of Parsol-1789(a photo-reactive and cosmetic agent) held inside the porous network of the microspheres.

  20. Controlled release behaviour and antibacterial effects of antibiotic-loaded titania nanotubes.

    Science.gov (United States)

    Feng, Wenchao; Geng, Zhen; Li, Zhaoyang; Cui, Zhenduo; Zhu, Shengli; Liang, Yanqin; Liu, Yunde; Wang, Renfeng; Yang, Xianjin

    2016-05-01

    Bacterial infections have been identified as the main cause of orthopaedic implant failure. Owing to their high antibiotic delivery efficiency, titania nanotubes loaded with antibiotics constitute one of the most promising strategies for suppressing bacterial infections. However, it is difficult to control the drug-release behaviour of such nanotubes. Although sealing the nanotubes with a polymer solution provides sustained release effects to a certain extent, it inevitably influences their initial antibacterial activity. This study reports on the controlled release of gentamicin sulphate (GS) from titania nanotube surfaces whereby their initial antibacterial activity remains unaffected. Titania nanotubes were fabricated via electrochemical anodization and loaded with GS through physical adsorption. Experimental results showed that this loading method is feasible and efficient. The GS-loaded titania nanotubes were further covered by a thin film comprising a mixture of GS and chitosan (GSCH). The release kinetics confirmed that the drug release could be controlled by this thin film. Moreover, such a film was shown to not only inhibit initial bacterial adherence owing to its strong antibacterial properties but also enhance cell viability. Thus, GS-loaded titania nanotubes coated with GSCH have considerable potential as biomaterials for preventing initial release and peri-implant infection in the field of orthopaedics.

  1. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jinjin [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhao, Chengjian [National Key Laboratory of Human Factors Engineering, Department of ECLSS, China Astronaut Researching and Training Center, Beijing, 100094 (China); Zhou, Jingfang [Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA, 5095 (Australia); Li, Chunxia [National Key Laboratory of Human Factors Engineering, Department of ECLSS, China Astronaut Researching and Training Center, Beijing, 100094 (China); Shao, Yiran; Shi, Chao [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhu, Yingchun, E-mail: yzhu@mail.sic.ac.cn [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-11-15

    Graphical abstract: - Highlights: • TiO{sub 2}/Ag feedstock powders containing 1–10,000 ppm silver nanoparticles were double sintered and deposited by plasma spray. • TiO{sub 2}/Ag coatings were composed of pure rutile phase and homogeneously-distributed metallic silver. • TiO{sub 2}/Ag coatings with more than 10 ppm silver nanoparticles exhibited strong antibacterial activity against E. coli and S. aureus. - Abstract: Rutile titania (TiO{sub 2}) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO{sub 2} coatings. In the study, titania-nanosilver (TiO{sub 2}/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO{sub 2} powders containing 1–10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO{sub 2}/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO{sub 2}/Ag coatings and no crystalline changed happened in the TiO{sub 2} structure. The reduction ratios on the TiO{sub 2}/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO{sub 2}/Ag coatings with 100–1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO{sub 2}/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the

  2. Microfabricated structures and devices featuring nanostructured titania thin films

    Science.gov (United States)

    Monkowski, Adam J.

    2007-05-01

    When titanium reacts with hydrogen peroxide at 80°C--100°C, a nanostructured titania (NST) thin film is formed on the titanium surface. This nanostructured film is particularly suited for integration with thin film and bulk microfabrication techniques. The ability to manufacture devices in a batch format is a principal advantage of microfabrication-based production. To reliably produce arrays of micro-patterned NST thin films on the wafer scale, a patterning guideline must be considered. The formation of NST relies on a re-deposition process; adequate ti-peroxo species must be generated and remain at the solid-solution interface. Numerical analysis of the characteristic transient diffusion behavior for various micro-patterns has been compared with experimental data to generate a criterion to guide the design of NST micro-patterns. Wafer scale arrays of NST micro gas-sensors have been fabricated using standard thin film techniques. Sensing elements are 20 mum on a side. High sensitivity to hydrogen is achieved by modification of the sensors with platinum nanoparticles. When exposed to a 10 mT partial pressure of hydrogen at 250°C, the functionalized devices exhibit more than one order of magnitude resistance decrease with a response time of approximately 7 sec. Titanium microstructures formed using the titanium ICP deep etch (TIDE) process have been integrated with NST films to produce an ordered nanostructure-microstructure composite (3D-NST). The process developed allows for the incorporation of a planar top surface, advantageous for bonding and sealing applications, in which the nanostructured thin film is formed only on feature sidewalls and floors. When titanium microstructures are spaced less than 1 mum apart, titania nanostructures bridge adjacent features. NST and 3D-NST structures have been assembled and tested in a dye-sensitized solar cell (DSSC) device. The NST film is approximately 900nm thick; this yielded a DSSC with an efficiency of 1.8%, similar

  3. Effect of phosphorous on the properties of titania produced from Ti-salt flocculated sludge in water treatment.

    Science.gov (United States)

    Shon, Ho Kyong; Okour, Yousef; El Salib, Ibrahim; Kim, Jong Beom; Kim, Jong-Ho

    2011-08-01

    In this study, the removal of phosphorous (P) using Ti-salt flocculation of biologically treated sewage effluent (BTSE) was investigated for a year. The pH, alkalinity and concentration of P, before and after Ti-salt flocculation, were measured and compared. The sludge of Ti-salt flocculation was incinerated at 600 degrees C to produce titania nanoparticles which found to be doped with P Titania nanoparticles were characterised and their photocatalytic activity under UV light irradiation were also tested. Results indicated that the removal of P, which exceeded 97% in average, was not affected by the pH and the alkalinity of BTSE. The concentration of P in titania had no effect on the characteristics of titania nanoparticles in different seasons. Titania nanoparticles exhibited superior properties in terms of BET surface area and photocatalytic activity.

  4. Improved Thermoelectric Performances of SrTiO3 Ceramic Doped with Nb by Surface Modification of Nanosized Titania.

    Science.gov (United States)

    Li, Enzhu; Wang, Ning; He, Hongcai; Chen, Haijun

    2016-12-01

    Nb-doped SrTiO3 ceramics doped with the surface modification of nanosized titania was prepared via liquid phase deposition approach and subsequent sintered in an Ar atmosphere. The surface modification of nanosized titania significantly improved the ratio of the electrical conductivity to thermal conductivity of SrTiO3 ceramic doped with Nb, and has little impact on the Seebeck coefficient, thus obviously improving the dimensionless thermoelectric figure of merit (ZT value). The surface modification of nanosized titania is a much better method to lower the thermal conductivity and to enhance the electrical conductivity than the mechanical mixing process of nanosized titania. The highest ZT value of 0.33 at 900 K was obtained. The reason for the improved thermoelectric performances by the surface modification of nano-sized titania was preliminary investigated.

  5. XPS Studies of Magnetic Multilayers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    NiOx/Ni81Fe19 and Co/AlOx/Co magnetic multilayers were fabri cated by reactive RF/DC magnetron sputtering on clean glass substrates and oxidized Si (100) substrates, respectively. The exchange biasing field (Hex) between NiOx and Ni81Fe19 as a function of oxidation stat es was studied by X-ray photoelectron spectroscopy (XPS). The oxidatio n states and the oxide thickness of Al layers in magnetic multilayer f ilms consisting of Co/AlOx/Co were also analyzed. It is found that the Hex of NiOx/Ni81Fe19 films only depends on Ni2+ but not on Ni3+ or Ni . The bottom Co can be completely covered by depositing an Al layer th icker than 2.0nm. The oxide layer was Al2O3, and its thickness was 1.1 5nm.

  6. Thermally induced delamination of multilayers

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Sarraute, S.; Jørgensen, O.

    1998-01-01

    Steady-state delamination of multilayered structures, caused by stresses arising during processing due to thermal expansion mismatch, is analyzed by a fracture mechanics model based on laminate theory. It is found that inserting just a few interlayers with intermediate thermal expansion coefficie...... coefficients may be an effective way of reducing the delamination energy release rate. Uneven layer thickness and increasing elastic mismatch are shown to raise the energy release rate. Experimental work confirms important trends of the model.......Steady-state delamination of multilayered structures, caused by stresses arising during processing due to thermal expansion mismatch, is analyzed by a fracture mechanics model based on laminate theory. It is found that inserting just a few interlayers with intermediate thermal expansion...

  7. Anomalous magnetoresistance in Fibonacci multilayers.

    Energy Technology Data Exchange (ETDEWEB)

    Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A. (Materials Science Division); (Universidade Federal do Rio Grande do Norte)

    2012-01-01

    We theoretically investigated magnetoresistance curves in quasiperiodic magnetic multilayers for two different growth directions, namely, [110] and [100]. We considered identical ferromagnetic layers separated by nonmagnetic layers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr multilayers, four terms were included in our description of the magnetic energy: Zeeman, cubic anisotropy, bilinear coupling, and biquadratic coupling. The minimum energy was determined by the gradient method and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. By choosing spacers with a thickness such that biquadratic coupling is stronger than bilinear coupling, unusual behaviors for the magnetoresistance were observed: (i) for the [110] case, there is a different behavior for structures based on even and odd Fibonacci generations, and, more interesting, (ii) for the [100] case, we found magnetic field ranges for which the magnetoresistance increases with magnetic field.

  8. Multilayer coating for high gradients

    CERN Document Server

    Kubo, Takayuki

    2016-01-01

    The multilayer coating for high gradients is reviewed. Not only the S-I-S structure, but also the S-S bilayer structure are also treated. This is an incomplete manuscript of an invited article which will be submitted to a journal. I have uploaded this version in order to help the understanding on my talk at the TESLA Technology Collaboration meeting at Saclay, France.

  9. Ultra-thin multilayer capacitors.

    Energy Technology Data Exchange (ETDEWEB)

    Renk, Timothy Jerome; Monson, Todd C.

    2009-06-01

    The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric constant, and standoff voltage. For successful device construction, there are a number of challenging requirements including achieving correct stoichiometric and crystallographic composition of the deposited PLZT, as well as the creation of a defect free homogenous film. This report details some success in satisfying these requirements, although 900 C temperatures were necessary for PLZT perovskite phase formation. These temperatures were applied to a previously deposited multi-layer film which was then post-annealed to this temperature. The film exhibited mechanical distress attributable to differences in the coefficient of thermal expansion (CTE) of the various layers. This caused significant defects in the deposited films that led to shorts across devices. A follow-on single layer deposition without post-anneal produced smooth layers with good interface behavior, but without the perovskite phase formation. These issues will need to be addressed in order for ion beam deposited MLCCs to become a viable technology. It is possible that future in-situ heating during deposition may address both the CTE issue, and result in lowered processing temperatures, which in turn could raise the probability of successful MLCC formation.

  10. Titania/C{sub n}TAB Nanoskeleton as adsorbent and photocatalyst for removal of alkylphenols dissolved in water

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Toshio, E-mail: tsakai@shinshu-u.ac.jp [Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan); Da Loves, Albar; Okada, Tomohiko; Mishima, Shozi [Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan)

    2013-03-15

    Highlights: ► Removal of alkylphenols from water by TiO{sub 2}/C{sub n}TAB Nanoskeleton. ► No significant adsorption of alkylphenols onto calcined TiO{sub 2}/C{sub n}TAB Nanoskeleton. ► Adsorption dominated by hydrophobic interaction between alkylphenols and C{sub n}TAB. ► Adsorption of alkylphenols promoted with C{sub n}TAB content in TiO{sub 2}/C{sub n}TAB Nanoskeleton. ► Complete removal of alkylphenols by adsorption and photocatalytic degradation. -- Abstract: We report here on the removal of alkylphenols (phenol, 4-n-propylphenol, 4-n-heptylphenol and 4-nonylphenol) dissolved in water using the composite particles of nanocrystalline titania and alkyltrimethylammonium bromide (C{sub n}H{sub 2n+1}N(CH{sub 3}){sub 3}Br, C{sub n}TAB; n = 12, 14, 16 and 18) (named as TiO{sub 2}/C{sub n}TAB Nanoskeleton) as adsorbents and photocatalysts. In particular, the adsorption of alkylphenols onto TiO{sub 2}/C{sub n}TAB Nanoskeleton in water was investigated in terms of hydrophobic interaction between alkylphenols and C{sub n}TAB, surface area, pore structure and crystal size of TiO{sub 2}/C{sub n}TAB Nanoskeleton. We revealed that C{sub n}TAB incorporated in the TiO{sub 2}/C{sub n}TAB Nanoskeleton promotes the adsorption of alkylphenols onto TiO{sub 2}/C{sub n}TAB Nanoskeleton due to the hydrophobic interaction between alkylphenols and C{sub n}TAB. On the other hand, the surface area, pore structure and crystal size of TiO{sub 2}/C{sub n}TAB Nanoskeleton did not affect the adsorption of alkylphenols onto TiO{sub 2}/C{sub n}TAB Nanoskeleton. We also found that the alkylphenols dissolved in water were completely removed by the combination of adsorption and photocatalytic degradation by the TiO{sub 2}/C{sub n}TAB Nanoskeleton under UV irradiation. These results prove that the TiO{sub 2}/C{sub n}TAB Nanoskeleton acts as in tandem an adsorbent and a photocatalyst for removal of alkylphenols dissolved in water.

  11. Highly efficient hydrophobic titania ceramic membranes for water desalination.

    Science.gov (United States)

    Kujawa, Joanna; Cerneaux, Sophie; Koter, Stanisław; Kujawski, Wojciech

    2014-08-27

    Hydrophobic titania ceramic membranes (300 kD) were prepared by grafting of C6F13C2H4Si(OC2H5)3 and C12F25C2H4Si(OC2H5)3 molecules and thus applied in membrane distillation (MD) process of NaCl solutions. Grafting efficiency and hydrophobicity were evaluated by contact angle measurement, atomic force microscopy, scanning electron microscopy, nitrogen adsorption/desorption, and liquid entry pressure measurement of water. Desalination of NaCl solutions was performed using the modified hydrophobic membranes in air gap MD (AGMD) and direct contact MD (DCMD) processes in various operating conditions. High values of NaCl retention coefficient (>99%) were reached. The permeate fluxes were in the range 231-3692 g·h(-1)·m(-2), depending on applied experimental conditions. AGMD mode appeared to be more efficient showing higher fluxes and selectivity in desalination. Overall mass transfer coefficients (K) for membranes tested in AGMD were constant over the investigated temperature range. However, K values in DCMD increased at elevated temperature. The hydrophobic layer was also stable after 4 years of exposure to open air.

  12. Liquid Phase Hydrogenation of Nitrobenzene over Nickel Supported on Titania

    Institute of Scientific and Technical Information of China (English)

    K.Joseph Antony RAJ; M.G.PRAKASH; R.MAHALAKSHMY; T.ELANGOVAN; B.VISWANATHAN

    2012-01-01

    The catalytic hydrogenation of nitrobenzene to aniline employing nickel impregnated on rutile,anatase,and high surface area titania supports has been investigated.The nickel is present in elemental state as fcc phase on the catalyst as evidenced by X-ray diffraction results.The Ni crystallite size was found to be greater for Ni/anatase.The temperature-programmed reduction results suggest a greater metal-support interaction for Ni/rutile.The observed order of catalytic activity for the hydrogenation of nitrobenzene is Ni/rutile > Ni/anatase > Ni/TiO2.A conversion of 99% was observed for Ni/rutile at 140 ℃ and hydrogen pressure of 1.96 MPa.Interestingly,aniline is the only product formed which demonstrates the catalytic hydrogenation of nitrobenzene proceeds with atom economy.Both Ni/rutile and Ni/anatase exhibited a better stability than Ni/TiO2.The hydrogenation proceeds with the preferential adsorption of hydrogen on nickel present in the catalyst surface,possibly assisted by TiOx species.

  13. Preparation of proton conducting membranes containing bifunctional titania nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Aslan, Ayse, E-mail: ayseaslan44@gmail.com; Bozkurt, Ayhan, E-mail: bozkurt@fatih.edu.tr [Fatih University, Department of Chemistry (Turkey)

    2013-07-15

    Throughout this work, the synthesis and characterization of novel proton conducting nanocomposite membranes including binary and ternary mixtures of sulfated nano-titania (TS), poly(vinyl alcohol) (PVA), and nitrilotri(methyl phosphonic acid) (NMPA) are discussed. The materials were produced by means of two different approaches where in the first, PVA and TS (10-15 nm) were admixed to form a binary system. The second method was the ternary nanocomposite membranes including PVA/TS/NMPA that were prepared at several compositions to get PVA-TS-(NMPA){sub x}. The interaction of functional nano particles and NMPA in the host matrix was explored by FT-IR spectroscopy. The homogeneous distribution of bifunctional nanoparticles in the membrane was confirmed by SEM micrographs. The spectroscopic measurements and water/methanol uptake studies suggested a complexation between PVA and NMPA, which inhibited the leaching of the latter. The thermogravimetry analysis results verified that the presence of TS in the composite membranes suppressed the formation of phosphonic acid anhydrides up to 150 Degree-Sign C. The maximum proton conductivity has been measured for PVA-TS-(NMPA){sub 3} as 0.003 S cm{sup -1} at 150 Degree-Sign C.

  14. Titania nanotube arrays as interfaces for neural prostheses.

    Science.gov (United States)

    Sorkin, Jonathan A; Hughes, Stephen; Soares, Paulo; Popat, Ketul C

    2015-04-01

    Neural prostheses have become ever more acceptable treatments for many different types of neurological damage and disease. Here we investigate the use of two different morphologies of titania nanotube arrays as interfaces to advance the longevity and effectiveness of these prostheses. The nanotube arrays were characterized for their nanotopography, crystallinity, conductivity, wettability, surface mechanical properties and adsorption of key proteins: fibrinogen, albumin and laminin. The loosely packed nanotube arrays fabricated using a diethylene glycol based electrolyte, contained a higher presence of the anatase crystal phase and were subsequently more conductive. These arrays yielded surfaces with higher wettability and lower modulus than the densely packed nanotube arrays fabricated using water based electrolyte. Further the adhesion, proliferation and differentiation of the C17.2 neural stem cell line was investigated on the nanotube arrays. The proliferation ratio of the cells as well as the level of neuronal differentiation was seen to increase on the loosely packed arrays. The results indicate that loosely packed nanotube arrays similar to the ones produced here with a DEG based electrolyte, may provide a favorable template for growth and maintenance of C17.2 neural stem cell line. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Hollow mesoporous titania microspheres: New technology and enhanced photocatalytic activity

    Science.gov (United States)

    Feng, Zhenliang; Wei, Wenrui; Wang, Litong; Hong, Ruoyu

    2015-12-01

    Hollow titania microspheres (HTS) were fabricated via a sol-gel process by coating the hydrolysis product of titanium tetrabutoxide (TBOT) onto the amino (-NH2) modified porous polystyrene cross-linked divinyl benzene (PS-DVB) microspheres under changing atmospheric pressure, followed by calcination in nitrogen and air atmosphere. Particularly, the atmospheric pressure was continuously and regularly changed during the formation process of PS-DVB@TiO2 microspheres. Then the TiO2 particles were absorbed into the pores and onto the surface of PS-DVB as well. The resultant HTS (around 2 μm in diameter) featured a high specific surface area (84.37 m2/g), anatase crystal and stable hollow microsphere structure, which led to high photocatalysis activity. The photocatalytic degradation of malachite green (MG) organic dye solution was conducted under ultraviolet (UV) light irradiation, which showed a high photocatalytic ability (81% of MG was degraded after UV irradiation for 88 min). Therefore, it could be potentially applied for the treatment of wastewater contaminated by organic pollutants.

  16. Nanocharacterization and bactericidal performance of silver modified titania photocatalyst.

    Science.gov (United States)

    Pan, Xubin; Medina-Ramirez, Iliana; Mernaugh, Ray; Liu, Jingbo

    2010-05-01

    An environmental-friendly procedure for manufacturing silver (Ag) and titania (TiO(2)) nanocomposites in an aqueous solution is presented. This green synthetic approach results in the successful production of nanomaterials with high dispersion and crystallinity. The colloidal suspensions of the nanocomposites composed of metal and ceramic (Ag-TiO(2)) were found to be extremely stable over a prolonged time period. Morphologically, nanocomposites were found to be composed of near-spherical particles that were highly crystalline. The nanocomposites were mono-dispersed with particles varying in size from 20 to 50nm, depending upon nanocomposite solution pH. Indexed metallic nanoscale silver exhibited a face-centered cubic (fcc) crystalline phase structure. Nanocomposite elemental composition studies indicated that the molar ratio of Ag and Ti was approximately 1-20. The binding energies and energy differences of Ag, Ti and O were well-indexed with their associated standard spectra. Nanocomposite optical absorption properties were consistent with noble metal nanoparticles. The zetapotential for the nanocomposites was higher at acidic pH and exhibited an absolute negative charge that apparently inhibited particle agglomeration. Escherichia coli (E. coli), a Gram-negative model microorganism was effectively inactivated using the nanocomposites under visible light at ambient temperature and pressure. The 'green chemistry' derived Ag-TiO(2) composites are applicable for the removal of biological impurities from drinking and underground water supplies. The results of the study indicated that nanocomposites could be specifically designed to prevent growth of bacteria in water.

  17. Water-photolysis properties of micron-length highly-ordered titania nanotube-arrays.

    Science.gov (United States)

    Varghese, Oomman K; Paulose, Maggie; Shankar, Karthik; Mor, Gopal K; Grimes, Craig A

    2005-07-01

    We report the water photoelectrolysis and photoelectrochemical properties of the titania nanotube arrays as a function of nanotube crystallinity, length (up to 6.4 microm), and pore size. Most noteworthy of our results, under 320-400 nm illumination (98 mW/cm2) the titania nanotube-array photoanodes (area 1 cm2), pore size 110 nm, wall thickness 20 nm, and 6 microm length, generate hydrogen by water photoelectrolysis at a rate of 7.6 mL/hr, with a photoconversion efficiency of 12.25%. The energy-time normalized hydrogen evolution rate is 80 mL/hrW, the largest reported hydrogen photoelectrolysis generation rate for any material system by a factor of four. The highly-ordered nanotubular architecture appears to allow for superior charge separation and charge transport, with a calculated quantum efficiency of over 80% for incident photons with energies larger than the titania bandgap.

  18. Properties and Application Perspective of Hybrid Titania-Silica Patterns Fabricated by Inkjet Printing.

    Science.gov (United States)

    Dzik, Petr; Veselý, Michal; Kete, Marko; Pavlica, Egon; Štangar, Urška Lavrenčič; Neumann-Spallart, Michael

    2015-08-01

    A hybrid titania-silica cold-setting sol has been developed that can be deposited onto a wide variety of surfaces without the need for high-temperature fixing and that is suitable for material printing deposition. Thin hybrid titania-silica coatings were patterned onto glass and PET substrates by inkjet printing. Well-defined hybrid titania-silica patterns, with thicknesses ranging from 40 to 400 nm, were fabricated by overprinting 1 to 10 layers. Excellent mechanical, optical, and photocatalytic properties were observed, making the reported material well suited for the fabrication of transparent self-cleaning coatings both on mineral and organic substrates. The printed patterns exhibit photoelectrochemical activity that can be further improved by thermal or photonic curing. A concept of fully printed interdigitated photoelectrochemical cells on flexible PET substrates utilizing the reported hybrid photocatalyst is disclosed as well.

  19. Osteoblast activity on anodized titania nanotubes: effect of simulated body fluid soaking time.

    Science.gov (United States)

    Bayram, Cem; Demirbilek, Murat; Calişkan, Nazli; Demirbilek, Melike Erol; Denkbaş, Emir Baki

    2012-06-01

    Early phase osseointegration is crucial for orthopedic implants. For the improvement of osseointegrative properties of orthopedic implants several surface modification methods such as acid etching, hydroxyapatite (HA) coating and sandblasting can be applied. In this article titanium implants were anodized to possess nanotubular titania structures on the surface. Titania nanotube structures with a 45-50 nm of average inner diameter were obtained and to enhance bioactivity, samples were soaked in 10X simulated body fluid (SBF) for apatite deposition on surface for different time periods (1, 2, 3, 5, 8 hours). Apatitic calcium phosphate deposited surfaces were analyzed with infrared spectrometry and wettability studies. Effect of soaking time on osteoblast cell was investigated by cell viability, alkaline phosphatase activity tests and morphological evaluations. As a result, 3 hours of soaking time was found as the optimum time period (p anodized titanium implants however excess and/or uncontrolled HA coating of titania layer limits the bioactive potential of the implant.

  20. The effects of anodization parameters on titania nanotube arrays and dye sensitized solar cells

    Science.gov (United States)

    Xie, Z. B.; Adams, S.; Blackwood, D. J.; Wang, J.

    2008-10-01

    Ordered, closely packed, and vertically oriented titania nanotube arrays with lengths exceeding 10 µm were fabricated by anodization of titanium foils. The effects of anodization voltage and time on the microstructural morphology and the photovoltaic performance of dye sensitized solar cells based on the titania nanotube arrays were investigated. On increasing the anodization voltage or time, the increase in active surface area leads to enhanced photovoltaic currents and thereby an overall higher performance of the dye sensitized solar cells. The efficiency enhancement with rising anodization voltage exceeds the increase in the outer surface area of the nanotubes, indicating that the active surface area is further enlarged by a more accessible inner surface of the nanotube arrays grown with a higher anodization voltage. A promising efficiency of 3.67% for dye sensitized solar cells based on anodized titania nanotube arrays was achieved under AM1.5, 100 mW cm-2 illumination.

  1. The effects of anodization parameters on titania nanotube arrays and dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Z B; Adams, S; Blackwood, D J; Wang, J [Department of Materials Science and Engineering, National University of Singapore, Singapore 117574 (Singapore)], E-mail: msexz@nus.edu.sg

    2008-10-08

    Ordered, closely packed, and vertically oriented titania nanotube arrays with lengths exceeding 10 {mu}m were fabricated by anodization of titanium foils. The effects of anodization voltage and time on the microstructural morphology and the photovoltaic performance of dye sensitized solar cells based on the titania nanotube arrays were investigated. On increasing the anodization voltage or time, the increase in active surface area leads to enhanced photovoltaic currents and thereby an overall higher performance of the dye sensitized solar cells. The efficiency enhancement with rising anodization voltage exceeds the increase in the outer surface area of the nanotubes, indicating that the active surface area is further enlarged by a more accessible inner surface of the nanotube arrays grown with a higher anodization voltage. A promising efficiency of 3.67% for dye sensitized solar cells based on anodized titania nanotube arrays was achieved under AM1.5, 100 mW cm{sup -2} illumination.

  2. Inhibition effect of phosphate on the crystal grain growth of nanosized titania

    Institute of Scientific and Technical Information of China (English)

    FENG Xiaohui; LIE Jingze; LI Ping; ZHANG Yanfeng; WEI Yu

    2009-01-01

    The inhibitory effect of phosphate on the crystal grain growth of nanosized titania during high temperature calcination was investigated. Nanosized titanium dioxide powders prepared by hydrolysis of titanium tetrachloride were soaked in phosphate solutions with different con-centrations. The obtained powders calcined at various temperatures were characterized by X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), and X-ray photoelectronic spectroscopy (XPS). The grain size of the samples without phosphate treatment in-creased quickly when calcined at high temperatures, while the grain size of the samples with phosphate modification increased slowly when calcined at the same temperature. This phenomenon implies that phosphate treatment plays an important role in inhibiting the crystal grain growth of titania. The possible mechanism of the inhibition effect of phosphate on titania is discussed.

  3. Preparation of Hard Coating Films with High Refractive Index from Titania Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam Woo; Ahn, Chi Yong; Song, Ki Chang [Konyang University, 121 Daehak-ro, Nonsan (Korea, Republic of)

    2015-12-15

    The titania (TiO{sub 2}) nanoparticles with a diameter 2-3 nm were synthesized by controlling hydrolysis of titanium tetraisopropoxide (TTIP) in acid solution. Organic-inorganic hybrid coating solutions were prepared by reacting the titania nanoparticles with 3-glycidoxypropyl trimethoxysilane (GPTMS) by the sol-gel method. The hard coating films with high refractive index were obtained by curing thermally at 120 .deg. C after spin-coating the coating solutions on the polycarbonate (PC) sheets. The coating films showed high optical transparency of 90% in the visible range and exhibited a pencil hardness of 2H. Also, the refractive index at 633 nm wavelength of coating films enhanced from 1.502 to 1.584 as the weight content of titania nanoparticles in the coating solutions increased from 4% to 25%.

  4. Synthesis of Nitrogen-doped Titania by Solvothermal Reactions in Alcohols

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nitrogen-doped titania nanoparticles were obtained by the homogeneous precipitation in hexamethylenetetraminetitanium trichloride-alcohol aqueous solutions at 90 ℃ followed by heating at 190 ℃. Anatase, rutile and brookite were obtained, where the crystallite size, specific surface area and color greatly changed as 5~50 nm, 20~200 m2/g and light gray to yellow, depending on the solvent and pH. The products after calcination were yellow, indicating doping with nitrogen ion. All colored titania showed photocatalytic activity under visible light irradiation for the oxidative decomposition of nitrogen monoxide in air. Especially, the nanoparticles of anatase type nitrogen-doped titania obtained using methanol aqueous solution showed excellent photocatalytic activity.

  5. Heterogeneous Photocatalytic Mineralization of Chlorobenzene by Paratungstate-loaded Titania Catalysts in an Aqueous Medium

    Institute of Scientific and Technical Information of China (English)

    YUE Bin; JIANG Lei; HU Chang-wen; CHEN Jian-min; HE He-yong

    2005-01-01

    Paratungstate-loaded titania catalysts were prepared via the addition of a series of aqueous solutions of paratungstate(denoted as W7) into an isopropanol solution of Ti[OCH(CH3)2]4 by means of the sol-gel method. The catalysts were characterized by EDX, BET, FTIR, UV-Vis DRS, XRD and the results indicate that such paratungstate-loaded catalysts maintained their heptatungstate structure in the anatase titania matrix up to 400 ℃. The catalysts were tested for the heterogeneous photodegradation of chlorobenzene in aqueous media and showed a better catalytic activity than P-25 TiO2 because paratungstate can prevent the recombination of the holes and electrons produced during irradiation. Moreover, the paratungstate-loaded titania catalysts can resist the disaggregation during the photoirradiation and can be easily recycled from the aqueous suspensions after reactions.

  6. Bioinspired hierarchical nanotubular titania immobilized with platinum nanoparticles for photocatalytic hydrogen production.

    Science.gov (United States)

    Liu, Xiaoyan; Li, Jiao; Zhang, Yiming; Huang, Jianguo

    2015-05-11

    A bioinspired nanocomposite composed of platinum nanoparticles and nanotubular titania was fabricated in which the titania matter was templated by natural cellulose substance. The composite possesses three- dimensional hierarchical structures, and ultrafine metallic platinum particles with sizes of ca. 2 nm were immobilized uniformly on the surfaces of the titania nanotubes. Such a nanocomposite with 1.06 wt % of platinum content shows the optimal photocatalytic hydrogen production activity from water splitting of 16.44 mmol h(-1)  g(-1) , and excessive loading of platinum results in poorer photocatalytic performance. The structural integrity of the nanocomposite upon cyclic water-splitting processes results in its sufficient photocatalytic stability.

  7. Synthesis, characterizations and photocatalytic studies of mesoporous titania prepared by using four plant skins as templates

    Energy Technology Data Exchange (ETDEWEB)

    Miao Yingchun [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China); Faculty of Chemical and Life Sciences, Qujing Normal University, Qujing 655000 (China); Zhai Zhongbiao [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China); Kunming Metallurgy Research Institute, Kunming 650031 (China); He Jiao; Li Bin; Li Junjie [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China); Wang Jiaqiang, E-mail: jqwang@ynu.edu.cn [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China)

    2010-07-20

    Anatase mesoporous titania with novel morphologies were synthesized by using the skins of tomatoes, bulb onions, grapes, and garlic bulbs, respectively, as templates and used for the photodegradation of Gentian violet, methyl violet, xylenol orange, and Rhodamine B under UV light. The samples were characterized by a combination of various physicochemical techniques, such as X-ray diffraction, SEM, HRTEM, N{sub 2} adsorption/desorption, diffuse reflectance UV-Vis, and FT-IR. It was found that all of the synthesized mesoporous titania samples exhibited similar morphologies to those of the original templates. The photoactivity of P25 TiO{sub 2} for the four dyes is nearly the same while the mesoporous titania samples synthesized by using the four skins as templates exhibited varied photoactivities for the four dyes.

  8. Preparation of nanostructured ruthenium doped titania for the photocatalytic degradation of 2-chlorophenol under visible light

    Directory of Open Access Journals (Sweden)

    Radwa A. Elsalamony

    2017-02-01

    Full Text Available Ru doped titania was prepared by the impregnation method and examined for the photocatalytic degradation of 2-chlorophenol at ambient conditions. Ru/TiO2 photocatalysts with metal loadings of 0.2, 0.4, 0.6 and 0.8 wt% were prepared and characterized using TEM, XRD, FTIR, SBET and EDX analyses. The degradation of 2-chlorophenol (2-CP in the aqueous phase was investigated under irradiation at 254 nm, employing either photodegradation in the presence of titania, Ru doped titania or photolysis, to compare the efficiency of these photoinduced advanced oxidation techniques. Photocatalysis under visible irradiation was also investigated. The removal efficiency arrived at 50% using 0.2% Ru/TiO2 catalyst.

  9. Structural, Optical and Electrical Properties of Nanocrystalline Cuprous Oxide Thin Film Deposited By Chemical Method

    Directory of Open Access Journals (Sweden)

    Prakash Bansilal Ahirrao

    2010-06-01

    Full Text Available Cuprous oxide (Cu2O is an interesting p-type semiconductor material used in solar cell applications.  The Modified Chemical Bath Deposition (M-CBD method is suitable for growing thin multilayer structure due to low deposition temperature. This method does not require any sophisticated instrument and substrate need not to be conductive. The nanocrystalline Cu2O thin films were deposited on glass substrates by M-CBD method. The deposited films were characterized by different characterization techniques to study structural, surface morphological, optical and electrical properties. The structural studies show that, the formation of Cu2O thin films with an average crystallite size of 14 nm. Optical studies show a direct band gap 2.48 eV. The room temperature electrical resistivity is of the order of 1.3 kW-cm and activation energy 0.33 eV. The films exhibit p-type electrical conductivity as seen by thermo-emf measurements.

  10. Direct growth of nanocrystalline hexagonal boron nitride films on dielectric substrates

    Energy Technology Data Exchange (ETDEWEB)

    Tay, Roland Yingjie [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Temasek Laboratories@NTU, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Tsang, Siu Hon [Temasek Laboratories@NTU, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Loeblein, Manuela; Chow, Wai Leong [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); CNRS-International NTU Thales Research Alliance CINTRA UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Singapore, Singapore 637553 (Singapore); Loh, Guan Chee [Institue of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632 (Singapore); Department of Physics, Michigan Technological University, Houghton, Michigan 49931 (United States); Toh, Joo Wah; Ang, Soon Loong [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Teo, Edwin Hang Tong, E-mail: htteo@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore)

    2015-03-09

    Atomically thin hexagonal-boron nitride (h-BN) films are primarily synthesized through chemical vapor deposition (CVD) on various catalytic transition metal substrates. In this work, a single-step metal-catalyst-free approach to obtain few- to multi-layer nanocrystalline h-BN (NCBN) directly on amorphous SiO{sub 2}/Si and quartz substrates is demonstrated. The as-grown thin films are continuous and smooth with no observable pinholes or wrinkles across the entire deposited substrate as inspected using optical and atomic force microscopy. The starting layers of NCBN orient itself parallel to the substrate, initiating the growth of the textured thin film. Formation of NCBN is due to the random and uncontrolled nucleation of h-BN on the dielectric substrate surface with no epitaxial relation, unlike on metal surfaces. The crystallite size is ∼25 nm as determined by Raman spectroscopy. Transmission electron microscopy shows that the NCBN formed sheets of multi-stacked layers with controllable thickness from ∼2 to 25 nm. The absence of transfer process in this technique avoids any additional degradation, such as wrinkles, tears or folding and residues on the film which are detrimental to device performance. This work provides a wider perspective of CVD-grown h-BN and presents a viable route towards large-scale manufacturing of h-BN substrates and for coating applications.

  11. Nanocrystalline germanium nip solar cells with spectral sensitivities extending into 1450 nm

    Science.gov (United States)

    Li, Chang; Ni, Jian; Sun, Xiaoxiang; Wang, Xinyu; Li, Zhenglong; Cai, Hongkun; Li, Juan; Zhang, Jianjun

    2017-02-01

    To absorb the infrared part of the solar spectrum more efficiently, narrow bandgap hydrogenated nanocrystalline germanium (nc-Ge:H) thin films were fabricated by radio frequency plasma enhanced chemical vapor deposition at a low temperature of 180 °C. While the incubation layer of the nc-Ge:H was reduced to less than 5 nm by using the ultra-high hydrogen dilution, the negative photoconductivity behavior was still observed as the thickness of nc-Ge:H up to 30 nm. Therefore, as the best candidate for solar cells application, the nc-Ge:H (20 nm)/nc-Si:H (10 nm) periodic multilayer structure was prepared and used as the absorption layer of nc-Ge:H nip solar cells. More importantly, the spectral sensitivities extending into the wavelength of 1450 nm were achieved in the nc-Ge:H nip solar cells. In addition, the annealing for the nc-Ge:H nip solar cells was carried out. While the overall short circuit current density of the device is improved after 500 °C annealing, the spectral sensitivities in the infrared region is decreased due to the the coalescence of Ge crystallites.

  12. Enhanced Photocatalytic Activity for Degradation of Methyl Orange over Silica-Titania

    Directory of Open Access Journals (Sweden)

    Yaping Guo

    2011-01-01

    Full Text Available Silica-modified titania (SMT powders with different atomic ratios of silica to titanium (Rx were successfully synthesized by a simple ultrasonic irradiation technique. The prepared samples were characterized by X-ray diffraction (XRD, FT-IR spectroscopy, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and ultraviolet visible spectroscopy. The specific surface area was measured according to BET theory. Results indicate that the addition of silica to titania can suppress the crystalline size growth and the transformation of anatase phase to rutile phase of titania, enlarge specific surface area of the titania particles, and result in a blue shift of absorption edge compared to pure titania. The photocatalytic activity of the SMT samples was evaluated by decolorizing methyl orange aqueous solutions under UV-visible light irradiation. It was found in our study that this activity was affected by silica content, calcination temperature, H2SO4, and oxidants such as KIO4, (NH42S2O8 and H2O2. The results reveal that the photocatalytic activity of 0.1-SMT catalyst is the best among all samples calcined at 550°C for 1 h and it is 1.56 times higher than that of Degussa P-25 titania, which is a widely used commercial TiO2 made by Germany Degussa company and has been most widely used in industry as photocatalyst, antiultraviolet product, and thermal stabilizer. The optimal calcination temperature for preparation was 550°C. The photocatalytic activity of SMT samples is significantly enhanced by H2SO4 solution treatment and oxidants.

  13. Learning Algorithms of Multilayer Neural Networks

    OpenAIRE

    Fujiki, Sumiyoshi; FUJIKI, Nahomi, M.

    1996-01-01

    A positive reinforcement type learning algorithm is formulated for a stochastic feed-forward multilayer neural network, with far interlayer synaptic connections, and we obtain a learning rule similar to that of the Boltzmann machine on the same multilayer structure. By applying a mean field approximation to the stochastic feed-forward neural network, the generalized error back-propagation learning rule is derived for a deterministic analog feed-forward multilayer network with the far interlay...

  14. Multi-layer seal for electrochemical devices

    Science.gov (United States)

    Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

    2010-09-14

    Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

  15. Multilayer Analysis and Visualization of Networks

    CERN Document Server

    De Domenico, Manlio; Arenas, Alex

    2014-01-01

    Multilayer relationships among and information about biological entities must be accompanied by the means to analyze, visualize, and obtain insights from such data. We report a methodology and a collection of algorithms for the analysis of multilayer networks in our new open-source software (muxViz). We demonstrate the ability of muxViz to analyze and interactively visualize multilayer data using empirical genetic and neuronal networks.

  16. Multi-layer seal for electrochemical devices

    Science.gov (United States)

    Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

    2010-11-16

    Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

  17. Preparation and characterization of aligned carbon nanotubes coated with titania nanoparticles

    Institute of Scientific and Technical Information of China (English)

    YU Hongtao; ZHAO Huimin; QUAN Xie; CHEN Shuo

    2006-01-01

    Well-aligned carbon nanotubes coated with titania (TiO2) were prepared by atmospheric pressure chemical vapor deposition (APCVD), and the sequential experiments including carbon nanotubes preparation, air-oxidation purification and titania nanoparticles coating were performed at different temperatures in the same reactor. Scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction patterns (XRD), and energy- dispersive X-ray spectra (EDX) demonstrated the well-aligned nanotubes and TiO2 nanoparticles in close proximity and the average diameter of TiO2 nanoparticles was 11.5 nm.

  18. THERMODYNAMIC AND PARTICLE-DYNAMIC STUDY FOR COMBUSTION SYNTHESIS OF TITANIA NANOPARTICLES

    Institute of Scientific and Technical Information of China (English)

    Ruoyu Hong; Zhiqiang Ren; Hongzhong Li

    2004-01-01

    Recent referential studies on combustion synthesis of titania nanoparticles were briefly reviewed. Computations based on the minimization of Gibbs free energy were conducted to find the equilibrium compositions, the optimal reaction temperature, the suitable mole ratio of oxygen to titanium tetrachloride, and the best inlet positions of titanium tetrachloride. The mean particle diameter was obtained from particle-dynamic simulation. A combustion apparatus was setup to synthesize titania nanoparticles by the oxidation and hydrolysis of titanium tetrachloride at high temperatures. Experimental investigation verified some results obtained from thermodynamic and particle-dynamic computations.

  19. Preparation and hydrogen 8as sensitive characteristics of highly ordered titania nanotube arrays

    Institute of Scientific and Technical Information of China (English)

    JI HuiMing; LU HuiXiang; MA DongFang; YU JianJun; MA ShiCai

    2008-01-01

    In this paper, we report the growth and characteristics of titania nanotube arrays prepared by anodic oxidation and then annealed in an oxygen atmosphere at 500℃. The titania nanotube arrays presented high sensitivity to hydrogen gas. The crystalline phase of the samples was checked by X-ray diffraction (XRD). The differences in the nanotubes morphology attributed to the etched samples due to anodiza-tion potential, reaction time and the electrolyte concentration were analyzed by scanning electron mi-croscopy (SEM). The gas sensitive parameters of the samples were obtained from resistance, the re-sponse time and the recovery time at different temperatures.

  20. Macroporous Titania Monolith Prepared via Sol-gel Process with Polymer Foam as the Template

    Institute of Scientific and Technical Information of China (English)

    REN, Jian; DU, Zhong-Jie; ZHANG, Chen; LI, Hang-Quan

    2006-01-01

    Macroporous titania monoliths were prepared via sol-gel method using polymer foam as templates. The polymer foam polymerized via concentrated emulsion polymerization was immerged in a solution of titanium(Ⅳ) isopropoxide in 2-propanol, which underwent a sol-gel process. The organic components were subsequently removed by calcination. The effects of various parameters, including the nature of the monomer, the volume fraction of dispersed phase of the concentrated emulsion, and concentration of the sol-gel solution were investigated. The SEM micrographs of the macroporous titania monoliths thus obtained showed that the porous structure of the final material was effectively controllable.

  1. Design of titania nanotube structures by focused laser beam direct writing

    Energy Technology Data Exchange (ETDEWEB)

    Enachi, Mihai [National Center for Materials Study and Testing, Technical University of Moldova, Stefan cel Mare av. 168, Chisinau, MD-2004 (Moldova, Republic of); Stevens-Kalceff, Marion A. [School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Sarua, Andrei [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Ursaki, Veaceslav [Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, MD-2028 (Moldova, Republic of); Tiginyanu, Ion, E-mail: tiginyanu@asm.md [National Center for Materials Study and Testing, Technical University of Moldova, Stefan cel Mare av. 168, Chisinau, MD-2004 (Moldova, Republic of); Institute of Electronic Engineering and Nanotechnologies, Academy of Sciences of Moldova, Chisinau, MD-2028 (Moldova, Republic of)

    2013-12-21

    In this work, we report on electrochemical fabrication of titania films consisting of nanotubes (NTs) and their treatment by focused laser beam. The results of sample characterization by optical and scanning electron microscopy, cathodoluminescence imaging, and Raman scattering scanning spectroscopy are compared to those inherent to specimens subjected to thermal treatment in a furnace. The obtained data demonstrate possibilities for controlling crystallographic structure of TiO{sub 2} NTs by focused laser beam direct writing. These findings open new prospects for the design and fabrication of spatial architectures based on titania nanotubes.

  2. Flow-directed assembly of non-spherical titania nanoparticles into superhydrophilic thin films

    Science.gov (United States)

    Ojha, Abhijeet; Thakker, Manish; Shah, Dinesh O.; Thareja, Prachi

    2016-03-01

    Superhydrophilic thin films of 21 nm sized non-spherical titania nanoparticles are fabricated from a colloidal suspension by fixed blade flow coating without UV illumination. At a blade angle of a = 36° and a gap of d = 300 µm, hierarchically structured films with increasing surface roughness along with microscopic voids are formed depending on the substrate velocity and the titania volume fraction. Increasing the roughness is shown to be concomitant to an increase in the hydrophilicity, eventually leading to superhydrophilicity or water contact angle less than 5°.

  3. Review: Plasma-enhanced chemical vapor deposition of nanocrystalline diamond

    Directory of Open Access Journals (Sweden)

    Katsuyuki Okada

    2007-01-01

    Full Text Available Nanocrystalline diamond films have attracted considerable attention because they have a low coefficient of friction and a low electron emission threshold voltage. In this paper, the author reviews the plasma-enhanced chemical vapor deposition (PE-CVD of nanocrystalline diamond and mainly focuses on the growth of nanocrystalline diamond by low-pressure PE-CVD. Nanocrystalline diamond particles of 200–700 nm diameter have been prepared in a 13.56 MHz low-pressure inductively coupled CH4/CO/H2 plasma. The bonding state of carbon atoms was investigated by ultraviolet-excited Raman spectroscopy. Electron energy loss spectroscopy identified sp2-bonded carbons around the 20–50 nm subgrains of nanocrystalline diamond particles. Plasma diagnostics using a Langmuir probe and the comparison with plasma simulation are also reviewed. The electron energy distribution functions are discussed by considering different inelastic interaction channels between electrons and heavy particles in a molecular CH4/H2 plasma.

  4. Interaction between a bisphosphonate, tiludronate, and biomimetic nanocrystalline apatites.

    Science.gov (United States)

    Pascaud, Patricia; Gras, Pierre; Coppel, Yannick; Rey, Christian; Sarda, Stéphanie

    2013-02-19

    Bisphosphonates (BPs) are well established as successful antiresorptive agents for the prevention and treatment of bone diseases such as osteoporosis and Paget's disease. The aim of this work was to clarify the reaction mechanisms between a BP molecule, tiludronate, and the nanocrystalline apatite surface. The adsorption of tiludronate on well-characterized synthetic biomimetic nanocrystalline apatites with homogeneous but different compositions and surface characteristics was investigated to determine the effect of the nanocrystalline apatite substrate on the adsorption behavior. The results show that the adsorption of tiludronate on nanocrystalline biomimetic apatite surfaces varies over a large range. The most immature apatitic samples exhibited the highest affinity and the greatest amount adsorbed at saturation. Maturation of the nanocrystals induces a decrease of these values. The amount of phosphate ion released per adsorbed BP molecule varied, depending on the nanocrystalline substrate considered. The adsorption mechanism, although associated with a release of phosphate ions, cannot be considered as a simple ion exchange process involving one or two phosphate ions on the surface. A two-step process is proposed consisting of a surface binding of BP groups to calcium ions associated with a proton release inducing the protonation of surface orthophosphate ions and their eventual solubilization.

  5. Synergistic strengthening effect of nanocrystalline copper reinforced with carbon nanotubes.

    Science.gov (United States)

    Wang, Hu; Zhang, Zhao-Hui; Hu, Zheng-Yang; Wang, Fu-Chi; Li, Sheng-Lin; Korznikov, Elena; Zhao, Xiu-Chen; Liu, Ying; Liu, Zhen-Feng; Kang, Zhe

    2016-05-17

    In this study, a novel multi-walled carbon nanotubes reinforced nanocrystalline copper matrix composite with super high strength and moderate plasticity was synthesized. We successfully overcome the agglomeration problem of the carbon nanotubes and the grain growth problem of the nanocrystalline copper matrix by combined use of the electroless deposition and spark plasma sintering methods. The yield strength of the composite reach up to 692 MPa, which is increased by 2 and 5 times comparing with those of the nanocrystalline and coarse copper, respectively. Simultaneously, the plasticity of the composite was also significantly increased in contrast with that of the nanocrystalline copper. The increase of the density of the carbon nanotubes after coating, the isolation effect caused by the copper coating, and the improvement of the compatibility between the reinforcements and matrix as well as the effective control of the grain growth of the copper matrix all contribute to improving the mechanical properties of the composite. In addition, a new strengthening mechanism, i.e., the series-connection effect of the nanocrystalline copper grains introduced by carbon nanotubes, is proposed to further explain the mechanical behavior of the nanocomposite.

  6. Surfactant-assisted sol gel preparation of high-surface area mesoporous TiO{sub 2} nanocrystalline Li-ion battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Casino, S. [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Di Lupo, F., E-mail: francesca.dilupo@polito.it [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Francia, C. [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Tuel, A. [IRCELYON, Institut de Recherches sur la Catalyse et l’environnement de Lyon, UMR 5256, CNRS-Université de Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); Bodoardo, S. [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Gerbaldi, C., E-mail: claudio.gerbaldi@polito.it [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy)

    2014-05-01

    Highlights: • Mesoporous TiO{sub 2} nanocrystalline lithium battery anodes with tunable morphology. • Simple sol–gel technique using different cationic surfactants is adopted. • Textural/morphological characteristics define the electrochemical behaviour. • TiO{sub 2} anatase using C16TAB exhibits stable performance after 200 cycles. • It shows promising prospects as high-voltage safe Li-ion battery anode. - Abstract: We here investigate the physico-chemical/morphological characteristics and cycling behaviour of several kinds of nanocrystalline TiO{sub 2} Li-ion battery anodes selectively prepared through a simple sol–gel strategy based on a low-cost titanium oxysulfate precursor, by mediation of different cationic surfactants having different features (e.g., chain lengths, counter ion, etc.): i.e., cetyl-trimethylammonium bromide (CTAB), cetyl-trimethylammonium chloride (CTAC), benzalkonium chloride (BC) or octadecyl-trimethyl ammonium bromide (C{sub 18}TAB). X-ray diffraction profiles reveal single phase anatase having good correspondence with the reference pattern when using short chain CTAB, while in the other cases the presence of chloride and/or an increased chain length affect the purity of the samples. FESEM analysis reveal nanosized particles forming cauliflower-like aggregates. TiO{sub 2} materials demonstrate mesoporous characteristics and large specific surface area ranging from 250 to 30 m{sup 2} g{sup −1}. Remarkably stable electrode performance are achieved by appropriately selecting the cationic surfactant and the surfactant/precursor ratio. Detailed analysis is provided on the effect of the reaction conditions upon the formation of mesoporous crystalline titania enlightening new directions for the development of high performing lithium storage electrodes by a simple and low cost sol–gel strategy.

  7. A study on flash sintering and related phenomena in titania and its composite with alumina

    Science.gov (United States)

    Shikhar

    In 2010, Cologna et. al. [1] reported that with a help of small electric field 120 Vcm-1, the sintering temperature of 3 mol % yittria stabilized zirconia could be brought down to 850°C from 1450°C. On top of reducing the temperature requirements, the green sample could be sintered from starting density of 50% to near full density in mere 5 seconds, a sintering rate three orders of magnitude higher than conventional methods. This discovery led to the emergence of a new field of enhanced sintering with electric field, named "Flash Sintering". The objective of this thesis is to understand the phenomenological behavior of flash-sintering and related phenomena on titania and its composites with alumina at elevated temperature. The possible mechanisms to explain flash sintering are discussed: Joule heating and the avalanche of defect generation [2], both induced by the rapid rise in conductivity just before the onset of the flash. Apparently, both mechanisms play a role. The thesis covers the response of pure titania and composites of titania-alumina under flash and compared with conventional sintering. We start with the sintering behavior of pure titania and observe lowering of sintering temperature requirements with higher applied electric field. The conductivity of titania during flash is also measured, and compared with the nominal conductivity of titania at equivalent temperatures. The conductivity during flash is determined to be have a different activation energy. For the composites of titania-alumina, effect of flash on the constrained sintering was studied. It is a known fact that sintering of one component of composite slows down when the other component of a different densification rate is added to it, called constrained sintering. In our case, large inclusions of alumina particles were added to nano-grained titania green compact that hindered its densification. Flash sintering was found to be overcoming this problem and near full densification was achieved

  8. Synthesis of PPy-like Nanocrystallines by Oriented Plasma Polymerization at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    FANG Xin-sheng; GUO Ying; XU Jin-zhou; ZHANG Jing

    2006-01-01

    Polymeric polypyrrole-like (PPy-like) nanocrystallines were fast synthesized through oriented plasma polymerization at atmospheric pressure and room temperature. The effects of discharge power on the nanocrystalline morphology were investigated. Larger power tends to produce longer nanocrystallines. 3 mm long nanowires were produced at the largest power in our experiment. TEM image and the sharp electronic diffraction spots in SAD suggest that the nanoparticles have a single crystal phase. The chemical structure of the nanocrystalline has been studied through FTIR, EDX etc. This novel polymerization method could have great applications in fabricating functional polymeric nanocrystallines.

  9. Biogenic C-doped titania templated by cyanobacteria for visible-light photocatalytic degradation of Rhodamine B.

    Science.gov (United States)

    He, Jiao; Zi, Guoli; Yan, Zhiying; Li, Yongli; Xie, Jiao; Duan, Deliang; Chen, Yongjuan; Wang, Jiaqiang

    2014-05-01

    Cyanobacteria, which occurred in eutrophic water harvest solar light to carry out photosynthesis with high efficiency. In this work, cyanobacteria (Microcystis sp.) were used as biotemplate to synthesize titania structure. The synthesized titania sample had similar morphology to that of the original template in spite of the fragile unicellular structures and extremely high water content of cyanobacterial cells. Incorporation of biogenic C, as well as the morphology inherited from biotemplate improved visible-light absorbance of the titania structure. The sample exhibited higher visible-light photocatalytic activity than commercial titania photocatalyst Degussa P25 for Rhodamine B (RhB) degradation. Compared with those C-doped titania photocatalysts prepared by other methods, cyanobacteria templated titania photocatalyst offer some potential for competitive advantages. The reported strategy opened up a new use for the cyanobacteria. It could also be used for titania in applications such as treatment of polluted water, dye-sensitized solar cells, or other regions. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  10. Functionalization of nanocrystalline diamond films with phthalocyanines

    Science.gov (United States)

    Petkov, Christo; Reintanz, Philipp M.; Kulisch, Wilhelm; Degenhardt, Anna Katharina; Weidner, Tobias; Baio, Joe E.; Merz, Rolf; Kopnarski, Michael; Siemeling, Ulrich; Reithmaier, Johann Peter; Popov, Cyril

    2016-08-01

    Phthalocyanine (Pc) derivatives containing different central metal atoms (Mn, Cu, Ti) and different peripheral chains were synthesized and comprehensively characterized. Their interaction with nanocrystalline diamond (NCD) films, as-grown by hot-filament chemical vapor deposition or after their modification with oxygen plasma to exchange the hydrogen termination with oxygen-containing groups, was studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The elemental composition as determined by XPS showed that the Pc were grafted on both as-grown and O-terminated NCD. Mn, Cu and Ti were detected together with N stemming from the Pc ring and S in case of the Ti-Pc from the peripheral ligands. The results for the elemental surface composition and the detailed study of the N 1s, S 2p and O 1s core spectra revealed that Ti-Pc grafted better on as-grown NCD but Cu-Pc and Mn-Pc on O-terminated films. Samples of Mn-Pc on as-grown and O-terminated NCD were further investigated by NEXAFS spectroscopy. The results showed ordering of the grafted molecules, laying flat on the H-terminated NCD surface while only the macrocycles were oriented parallel to the O-terminated surface with the peripheral chains perpendicular to it.

  11. Nanocrystalline films for gas-reactive applications

    Science.gov (United States)

    Eastman, Jeffrey A.; Thompson, Loren J.

    2004-02-17

    A gas sensor for detection of oxidizing and reducing gases, including O.sub.2, CO.sub.2, CO, and H.sub.2, monitors the partial pressure of a gas to be detected by measuring the temperature rise of an oxide-thin-film-coated metallic line in response to an applied electrical current. For a fixed input power, the temperature rise of the metallic line is inversely proportional to the thermal conductivity of the oxide coating. The oxide coating contains multi-valent cation species that change their valence, and hence the oxygen stoichiometry of the coating, in response to changes in the partial pressure of the detected gas. Since the thermal conductivity of the coating is dependent on its oxygen stoichiometry, the temperature rise of the metallic line depends on the partial pressure of the detected gas. Nanocrystalline (<100 nm grain size) oxide coatings yield faster sensor response times than conventional larger-grained coatings due to faster oxygen diffusion along grain boundaries rather than through grain interiors.

  12. Rheology of nanocrystalline cellulose aqueous suspensions.

    Science.gov (United States)

    Shafiei-Sabet, Sadaf; Hamad, Wadood Y; Hatzikiriakos, Savvas G

    2012-12-11

    The rheological properties and microstructure of nanocrystalline cellulose (NCC) aqueous suspensions have been investigated at different concentrations. The suspension is isotropic up to 3 wt %, and phase separates to liquid crystalline and isotropic domains at higher concentrations where the samples exhibit a fingerprint texture and the viscosity profile shows a three-region behavior, typical of liquid crystals. The suspension behaves as a rheological gel at even higher concentrations where the viscosity profile shows a single shear thinning behavior over the whole range of shear rates investigated. The effects of ultrasound energy and temperature on the rheological properties and structure of these suspensions were studied using polarized optical microscopy and rheometry. Our results indicate that the amount of applied ultrasound energy affects the microstructure of the suspensions and the pitch of the chiral nematic domains. The viscosity profile is changed significantly at low shear rates, whereas the viscosity of biphasic suspensions at intermediate and high shear rates decreased with increasing temperature. This suggests that, between 30 and 40 °C, structural rearrangement takes place. At higher concentrations of about 10 wt %, the temperature has no significant effect on viscosity; however, a marked increase in viscosity has been observed at around 50 °C. Finally, the Cox-Merz rule was found to fail after a critical concentration, thereby implying significant structural formation. This critical concentration is much higher for sonicated compared to unsonicated suspensions.

  13. Mesoporous junctions and nanocrystalline solar cells

    Science.gov (United States)

    Graetzel, Michael

    2000-03-01

    Learning from the concepts used by green plants, we have developed a molecular photovoltaic system based on the sensitization of nanocrystalline TiO2 films. In analogy to photosyntesis, light is absorbed by a monolayer of dye attached to the surface of a wide-band-gap oxide. The mesoporous morphology of the layer provides a substrate characterized by a very large surface area. The roughness factor of a 10-micron thick film reaches easily 1000. Light penetrating the dye loaded TiO2 nanocrystals is therefore collected in an efficient manner, similar to the thylakoid vesicles in green leafs which are stacked in order to enhance solar light harvesting. The excited dye injects an electron in the conduction band of the oxide resulting in efficient and very rapid charge separation. Nearly quantitative conversion of photons in electric current have been achieved with these devices over the whole visible and near-IR range of the spectrum. The overall AM 1.5 solar-to electric power conversion efficiency has reached already 11unravel the dynamics of interfacial charge transfer reactions at these dye- sensitized heterojunctions.

  14. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new mechanical electrodeposition technology was proposed, and nanocrystalline nickel deposit with bright and smooth surface was prepared in the bath without any additive agents. Unlike traditional methods, the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing. Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits, pinholes and nodules. Furthermore, comparing with the deposit prepared by traditional methods, the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm. Every diffraction peak’s intensity of the deposit was reduced, the preferential orientation degree of (200) decreased and those of (111) and (220) increased. The microhardness notably increased. The magnetic properties were also changed with decreased saturation magnetization and increased coercive force. It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.

  15. Microhardness studies of nanocrystalline calcium tungstate

    Energy Technology Data Exchange (ETDEWEB)

    Anandakumar, V.M. [Department of Physics, Mahatma Gandhi College, Thiruvananthapuram (India); Khadar, M.A. [Centre for Nanoscience and Nanotechnology and Department of Physics, University of Kerala, Thiruvananthapuram (India)

    2008-02-15

    Nanocrystals of calcium tungstate (CaWO{sub 4}) of three different grain sizes were synthesized through chemical precipitation technique and the grain sizes and crystal structure were determined using the broadening of X-ray diffraction patterns and transmission electron microscopy. The microhardness of compacted pellets of nanocrystalline calcium tungstate (CaWO{sub 4}) with different grain sizes were measured using a Vickers microhardness tester for various applied loads ranging from 0.049 N to 1.96 N. The values of microhardness showed significant reverse indentation size effect at low indentation loads. The microhardness data obtained for samples of different grain sizes showed grain size dependent strengthening obeying normal Hall-Petch relation. The dependence of compacting pressure and annealing temperature on microhardness of the nanostructured sample with grain size of 13 nm were also studied. The samples showed significant increase in microhardness as the compacting pressure and annealing time were increased. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. High energy milling of zirconia-titania powders synthesized by coprecipitation; Moagem de alta energia em pos de zirconia-titania sintetizados por co-precipitacao

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Cristiano M.B.; Marchi, Juliana; Lazar, Dolores R.R.; Ussui, Valter, E-mail: vussui@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    Zirconia based ceramics are known by its remarkable mechanical properties as hardness and fracture toughness and in biomedical applications are classified as bioinert. By its turn, titania ceramics has been studied due to its ability to bond directly to bone tissue, but are structurally brittle. Properties of ceramics are strongly dependent of physical and chemical characteristics of its former powders. In the present work, research done for the synthesis of zirconia-titania ceramics by the coprecipitation route are presented, emphasizing the conditioning process through a high energy milling in a atritor mill, classifying of powders in vibratory sieves and forming of cylindrical ceramic samples followed by a sintering process at 1500 deg C for 01 hour. The intermediary samples produced in the various steps of the process were characterized by scanning electronic microscope, X-ray diffraction, nitrogen gas adsorption and granulometric analysis. (author)

  17. Microstructure characterization and cation distribution of nanocrystalline cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Y.M., E-mail: ymabbas@live.com [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Mansour, S.A.; Ibrahim, M.H. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Ali, Shehab E., E-mail: shehab_physics@yahoo.com [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt)

    2011-11-15

    Nanocrystalline cobalt ferrite has been synthesized using two different methods: ceramic and co-precipitation techniques. The nanocrystalline ferrite phase has been formed after 3 h of sintering at 1000 deg. C. The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction and the Rietveld method. The refinement result showed that the type of the cationic distribution over the tetrahedral and octahedral sites in the nanocrystalline lattice is partially an inverse spinel. The transmission electronic microscope analysis confirmed the X-ray results. The magnetic properties of the samples were characterized using a vibrating sample magnetometer. - Highlights: > The refinement result showed that the cationic distribution over the sites in the lattice is partially an inverse spinel. > The transmission electronic microscope analysis confirmed the X-ray results. > The magnetic properties of the samples were characterized using a vibrating sample magnetometer.

  18. In vivo evaluation of matrix pellets containing nanocrystalline ketoprofen.

    Science.gov (United States)

    Vergote, G J; Vervaet, C; Van Driessche, I; Hoste, S; De Smedt, S; Demeester, J; Jain, R A; Ruddy, S; Remon, J P

    2002-06-20

    The aim of this study was to evaluate the in-vivo behaviour of matrix pellets formulated with nanocrystalline ketoprofen after oral administration to dogs. No significant differences in AUC-values were seen between pellet formulations containing nanocrystalline or microcrystalline ketoprofen and a commercial ketoprofen formulation (reference: Rofenid 200 Long Acting). C(max) of the formulations containing nano- or microcrystalline ketoprofen was significantly higher compared to reference, whereas t(max) was significantly lower. The in-vivo burst release observed for the spray dried nanocrystalline ketoprofen matrix pellets was reduced following compression of the pellets in combination with placebo wax/starch pellets. These matrix tablets sustained the ketoprofen plasma concentrations during 5.6 and 5.4 h for formulations containing nano- and microcrystalline ketoprofen, respectively.

  19. High-pressure structural behavior of nanocrystalline Ge

    DEFF Research Database (Denmark)

    Wang, H.; Liu, J. F.; Yan, H.;

    2007-01-01

    The equation of state and the pressure of the I-II transition have been studied for nanocrystalline Ge using synchrotron x-ray diffraction. The bulk modulus and the transition pressure increase with decreasing particle size for both Ge-I and Ge-II, but the percentage volume collapse at the transi......The equation of state and the pressure of the I-II transition have been studied for nanocrystalline Ge using synchrotron x-ray diffraction. The bulk modulus and the transition pressure increase with decreasing particle size for both Ge-I and Ge-II, but the percentage volume collapse...... at the transition remains constant. Simplified models for the high-pressure structural behaviour are presented, based on the assumption that a large fraction of the atoms reside in grain boundary regions of the nanocrystalline material. The interface structure plays a significant role in affecting the transition...

  20. Ferromagnetism appears in nitrogen implanted nanocrystalline diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Remes, Zdenek [Institute of Physics ASCR v.v.i., Cukrovarnicka 10, 162 00 Prague 6 (Czech Republic); Sun, Shih-Jye, E-mail: sjs@nuk.edu.tw [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Varga, Marian [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Chou, Hsiung [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Hsu, Hua-Shu [Department of Applied Physics, National Pingtung University of Education, Pingtung 900, Taiwan (China); Kromka, Alexander [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Horak, Pavel [Nuclear Physics Institute, 250 68 Rez (Czech Republic)

    2015-11-15

    The nanocrystalline diamond films turn to be ferromagnetic after implanting various nitrogen doses on them. Through this research, we confirm that the room-temperature ferromagnetism of the implanted samples is derived from the measurements of magnetic circular dichroism (MCD) and superconducting quantum interference device (SQUID). Samples with larger crystalline grains as well as higher implanted doses present more robust ferromagnetic signals at room temperature. Raman spectra indicate that the small grain-sized samples are much more disordered than the large grain-sized ones. We propose that a slightly large saturated ferromagnetism could be observed at low temperature, because the increased localization effects have a significant impact on more disordered structure. - Highlights: • Nitrogen implanted nanocrystalline diamond films exhibit ferromagnetism at room temperature. • Nitrogen implants made a Raman deviation from the typical nanocrystalline diamond films. • The ferromagnetism induced from the structure distortion is dominant at low temperature.

  1. Solvothermal synthesis of nanocrystalline FeS2

    Institute of Scientific and Technical Information of China (English)

    CHEN Yanhua; ZHENG Yufeng; ZHANG Xiaogang; SUN Yanfei; DONG Youzhong

    2005-01-01

    This paper reports on the synthesis of the nanocrystalline FeS2 via a solvent-thermal process. Using FeSO4 and NH2CSNH2 as precursors and polyvinyl- pyrrolidone (PVP) as a protective agent (dispersant), we have successfully synthesized nanocrystalline FeS2 both under acidic conditions (Ph = 5) and under alkali conditions (Ph = 10) at various temperatures and for different time in alcohol-water solution. X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Ultraviolet Visible (UV-VIS) spectroscopy were used to characterize the morphology, structure, particle size and optical characterization of sample synthesized under acidic condition, and the XRD pattern was refined by Rietveld method. The experimental result shows that nanocrystalline FeS2 with uniform size, highly crystallized quality and excellent dispersivity has been synthesized at 200℃for 36 h.

  2. Mesoporous silica and organosilica films templated by nanocrystalline chitin.

    Science.gov (United States)

    Nguyen, Thanh-Dinh; Shopsowitz, Kevin E; MacLachlan, Mark J

    2013-11-04

    Liquid crystalline phases can be used to impart order into inorganic solids, creating materials that mimic natural architectures. Herein, mesoporous silica and organosilica films with layered structures and high surface areas have been templated by nanocrystalline chitin. Aqueous suspensions of spindle-shaped chitin nanocrystals were prepared by sequential deacetylation and hydrolysis of chitin fibrils isolated from king crab shells. The nanocrystalline chitin self-assembles into a nematic liquid-crystalline phase that has been used to template silica and organosilica composites. Removal of the chitin template by either calcination or sulfuric-acid-catalyzed hydrolysis gave mesoporous silica and ethylene-bridged organosilica films. The large, crack-free mesoporous films have layered structures with features that originate from the nematic organization of the nanocrystalline chitin.

  3. Sustainable commercial nanocrystalline cellulose manufacturing process with acid recycling.

    Science.gov (United States)

    Sarma, Saurabh Jyoti; Ayadi, Mariem; Brar, Satinder Kaur; Berry, Richard

    2017-01-20

    Nanocrystalline cellulose (NCC) is a biomaterial having potential applications in a wide range of industries. It is industrially produced by concentrated acid hydrolysis of cellulosic materials. In this process, the sulfuric acid rich liquor can be concentrated and reused. However, removal of sugar monomers and oligomers is necessary for such recycling. Membrane and ion exchange technology can be employed to remove sugars; however, such technologies are not efficient in meeting the quality required to recycle the acid solution. As a part of the present study, activated carbon (AC) has been evaluated as an adsorbent for sugar removal from the acidic solution generated during commercial nanocrystalline cellulose manufacturing process. Almost complete removal of sugar can be achieved by this approach. The maximum sugar removal observed during this study was 3.4g/g of AC. Based on this finding, a sustainable method has been proposed for commercial nanocrystalline cellulose manufacturing.

  4. Modeling the deformation behavior of nanocrystalline alloy with hierarchical microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hongxi; Zhou, Jianqiu, E-mail: zhouj@njtech.edu.cn [Nanjing Tech University, Department of Mechanical Engineering (China); Zhao, Yonghao, E-mail: yhzhao@njust.edu.cn [Nanjing University of Science and Technology, Nanostructural Materials Research Center, School of Materials Science and Engineering (China)

    2016-02-15

    A mechanism-based plasticity model based on dislocation theory is developed to describe the mechanical behavior of the hierarchical nanocrystalline alloys. The stress–strain relationship is derived by invoking the impeding effect of the intra-granular solute clusters and the inter-granular nanostructures on the dislocation movements along the sliding path. We found that the interaction between dislocations and the hierarchical microstructures contributes to the strain hardening property and greatly influence the ductility of nanocrystalline metals. The analysis indicates that the proposed model can successfully describe the enhanced strength of the nanocrystalline hierarchical alloy. Moreover, the strain hardening rate is sensitive to the volume fraction of the hierarchical microstructures. The present model provides a new perspective to design the microstructures for optimizing the mechanical properties in nanostructural metals.

  5. Kinetic constants of abnormal grain growth in nanocrystalline nickel

    Science.gov (United States)

    Aleshin, A. N.

    2016-02-01

    The grain growth in nanocrystalline nickel with a purity of 99.5 at % during non-isothermal annealing was experimentally investigated using differential scanning calorimetry and transmission electron microscopy. Nanocrystalline nickel was prepared by electrodeposition and had an average grain size of approximately 20 nm. It was shown that, at a temperature corresponding to the calorimetric signal peak, abnormal grain growth occurs with the formation of a bimodal grain microstructure. Calorimeters signals were processed within the Johnson-Mehl-Avrami formalism. This made it possible to determine the exponent of the corresponding equation, the frequency factor, and the activation energy of the grain growth, which was found to be equal to the activation energy of the vacancy migration. The reasons for the abnormal grain growth in nanocrystalline nickel were discussed.

  6. Nanocrystalline and ultrafine grain copper obtained by mechanical attrition

    Directory of Open Access Journals (Sweden)

    Rodolfo Rodríguez Baracaldo

    2011-03-01

    Full Text Available This article presents a method for the sample preparation and characterisation of bulk copper having grain size lower than 1 μm (ultra-fine grain and lower than 100 nm grain size (nanocrystalline. Copper is initially manufactured by a milling/alloying me- chanical method thereby obtaining a powder having a nanocrystalline structure which is then consolidated through a process of warm compaction at high pressure. Microstructural characterisation of bulk copper samples showed the evolution of grain size during all stages involved in obtaining it. The results led to determining the necessary conditions for achieving a wide range of grain sizes. Mechanical characterisation indicated an increase in microhardness to values of around 3.40 GPa for unconsolida- ted nanocrystalline powder. Compressivee strength was increased by reducing the grain size, thereby obtaining an elastic limit of 650 MPa for consolidated copper having a ~ 62 nm grain size.

  7. Effect of titania on fired characteristics of triaxial porcelain

    Indian Academy of Sciences (India)

    Sunipa Bhattacharyya; Swapan Kumar Das; Nirendra Krishna Mitra

    2005-08-01

    Titania was progressively added in the range 3–9 wt% into a triaxial porcelain body consisting of clay, quartz and feldspar. The composed bodies were heated at five different temperatures in the range 1200–1400°C and their fired properties as well as phases evolved were studied. The results revealed that beyond 1300°C, formation of more liquid phases caused bloating in samples which led to generation of pores. This effect is more pronounced in TiO2 containing samples. In the present system, 1300°C appeared to be the optimum temperature at which porosity was almost negligible and strength was maximum (45 MPa), particularly in presence of TiO2. From the results of XRD studies, it was revealed that quartz content primarily decreased with increase in TiO2 content due to excess glass formation and its subsequent dissolution. Mullite content increased with increase in TiO2 content. No significant effect was observed beyond 6 wt% addition. Microstructure primarily showed the presence of quartz grain and cluster of smaller sized primary mullite crystals in both the samples without and with TiO2. Very few secondary mullite crystals were also observed. SEM picture of sample containing 9 wt% TiO2 showed some grain boundary crack due to cooling stress generated in the glassy phase. The drastic reduction of residual strength after 8 cycles of heating at 800°C and cooling particularly in TiO2 containing samples suggests controlled heat treatment of the vitrified samples necessary to promote secondary crystallization process for the enhancement of strength. Attempts have also been made to correlate the constitutional parameters with the properties.

  8. Multi-Layer Traffic Steering

    DEFF Research Database (Denmark)

    Fotiadis, Panagiotis; Polignano, Michele; Gimenez, Lucas Chavarria

    2013-01-01

    This paper investigates the potentials of traffic steering in the Radio Resource Control (RRC) Idle state by evaluating the Absolute Priorities (AP) framework in a multilayer Long Term Evolution (LTE) macrocell scenario. Frequency priorities are broadcast on the system information and RRC Idle...... users can be steered towards higher priority carriers whenever coverage allows it. However, such an approach may overload the prioritized layers. For that purpose, an enhanced scheme is proposed, where priorities are adjusted on a user basis and are provided to the terminal via the connection release...

  9. Electronic structure of nanocrystalline and polycrystalline hydrogen storage materials

    Energy Technology Data Exchange (ETDEWEB)

    Smardz, L. [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17 Street, 60-179 Poznan (Poland); Jurczyk, M.; Smardz, K.; Nowak, M.; Makowiecka, M.; Okonska, I. [Institute of Materials Science and Engineering, Poznan University of Technology, M. Sklodowska-Curie 5 Sq., 60-965 Poznan (Poland)

    2008-02-15

    To optimise the choice of the compounds for a selected application, a better understanding of the role of each alloy constituent on the electronic properties of the material is crucial. In this work, we study experimentally the electronic properties of nanocrystalline and polycrystalline (Mg{sub 1-x}M{sub x}){sub 2}Ni, (Mg{sub 1-x}M{sub x}){sub 2}Cu, La(Ni{sub 1-x}M{sub x}){sub 5}, and Ti(Ni{sub 1-x}M'{sub x}) (M = Mn, Al; M' = Fe, Mg, Zr) alloys. The nanocrystalline and polycrystalline samples were prepared by mechanical alloying (MA) followed by annealing and arc melting method, respectively. All X-ray photoelectron spectroscopy (XPS) spectra were measured immediately after cleaning of the sample surface in a vacuum of 8 x 10{sup -11} mbar. Furthermore, we have measured XPS spectra of in situ prepared nanocrystalline and polycrystalline LaNi{sub 5}, TiNi, and Mg{sub 2}Ni thin films and compared with those obtained for ex situ prepared bulk materials. The substitution of Mg in Mg{sub 2}Ni and Mg{sub 2}Cu, Ni in LaNi{sub 5} and TiNi by transition metals leads to significant modifications of the shape and width of the valence band of the nanocrystalline as well as polycrystalline samples. Especially, the valence bands of the MA nanocrystalline alloys are considerably broader compared to those measured for the polycrystalline samples. Results also showed that the strong modifications of the electronic structure of the nanocrystalline alloys could significantly influence on their hydrogenation properties. (author)

  10. Superhard nano-multilayers and nanocomposite coatings

    Institute of Scientific and Technical Information of China (English)

    BAI Xiaoming; ZHENG Weitao; AN Tao

    2005-01-01

    This paper reviews the recent development of nano-multilayers and nanocomposite coatings. The hardening mechanisms and design of hard coating are discussed in details. Recent research on Ti/TiN and nitride/nitride multilayer, Ti-Si-N and Ti-Al-Si-N nanocomposite coatings is described, and the perspectives of the related research are proposed.

  11. Multilayer Graphene for Waveguide Terahertz Modulator

    DEFF Research Database (Denmark)

    Khromova, I.; Andryieuski, Andrei; Lavrinenko, Andrei

    2014-01-01

    We study terahertz to infrared electromagnetic properties of multilayer graphene/dielectric artificial medium and present a novel concept of terahertz modulation at midinfrared wavelengths. This approach allows the realization of high-speed electrically controllable terahertz modulators based...... on hollow waveguide sections filled with multilayer graphene....

  12. Multi-Layer E-Textile Circuits

    Science.gov (United States)

    Dunne, Lucy E.; Bibeau, Kaila; Mulligan, Lucie; Frith, Ashton; Simon, Cory

    2012-01-01

    Stitched e-textile circuits facilitate wearable, flexible, comfortable wearable technology. However, while stitched methods of e-textile circuits are common, multi-layer circuit creation remains a challenge. Here, we present methods of stitched multi-layer circuit creation using accessible tools and techniques.

  13. Diffusion phenomena in chemically stabilized multilayer structures

    NARCIS (Netherlands)

    Bruijn, Saskia

    2011-01-01

    Multilayered thin film structures are widely applied as reflective coatings for optical elements in the extreme ultraviolet wavelength regime. In this thesis we investigate the structural and chemical changes that occur in Mo/Si based multilayers as a result of radiation induced thermal loads and ot

  14. Crossplatform C++ library for multilayer perceptron learning

    Directory of Open Access Journals (Sweden)

    Дмитрий Тариельевич Ибадов

    2016-05-01

    Full Text Available Cross-platform C++ library is developed. It provides classes enabling to create multilayer perceptron and its training by supervised learning method (backpropagation. Resulting artificial network is able to classify incoming data after previous training. Multilayer perceptron training results and its ability to classify test dataset are tested

  15. Research Update: Phonon engineering of nanocrystalline silicon thermoelectrics

    Science.gov (United States)

    Shiomi, Junichiro

    2016-10-01

    Nanocrystalline silicon thermoelectrics can be a solution to improve the cost-effectiveness of thermoelectric technology from both material and integration viewpoints. While their figure-of-merit is still developing, recent advances in theoretical/numerical calculations, property measurements, and structural synthesis/fabrication have opened up possibilities to develop the materials based on fundamental physics of phonon transport. Here, this is demonstrated by reviewing a series of works on nanocrystalline silicon materials using calculations of multiscale phonon transport, measurements of interfacial heat conduction, and synthesis from nanoparticles. Integration of these approaches allows us to engineer phonon transport to improve the thermoelectric performance by introducing local silicon-oxide structures.

  16. Nanocrystalline and Nanocomposite Magnetic Materials and Their Applications

    Institute of Scientific and Technical Information of China (English)

    Robert D Shull

    2007-01-01

    Nanocrystalline materials can possess bulk properties quite different from those commonly associated with conventional large-grained materials. Nanocomposites, a subset of nanocrystalline materials, in addition have been found to possess magnetic properties which are similar to, but different from, the properties of the individual constituents. New magnetic phenomena, unusual property combinations, and both enhanced and diminished magnetic property values are just some of the changes observed in magnetic nanocomposites from conventional magnetic materials. Here, a description will be presented of some of the exciting new properties discovered in nanomaterials and the magnetic applications envisioned for them.

  17. Thermodynamic properties and phase stability of nanocrystalline metals

    Institute of Scientific and Technical Information of China (English)

    SONG Xiaoyan; LI Lingmei; ZHANG Jiuxing

    2006-01-01

    The fundamental thermodynamic functions of enthalpy, entropy, and Gibbs free energy, as functions of the excess free volume at interfaces, temperature, and grain size, have been derived for single-phase metal nanocrystals. The model was applied to predict the thermal features of nano-grain boundaries and the characteristics of phase transformation in nanocrystalline metals, such as the transformation temperature and the critical grain size for phase transformation at a given temperature. The model predictions have been verified by experimental studies on the β-Co (→) α-Co phase transformation in nanocrystalline Co prepared by ball milling.

  18. Preparation of nanocrystalline BaTiO3 ceramics

    Institute of Scientific and Technical Information of China (English)

    DENG XiangYun; LI DeJun; LI JianBao; WANG XiaoHui; LI LongTu

    2009-01-01

    The high-dense nanocrystalline BaTiO3 (BT) ceramics with grain size smaller than 100 nm have been successfully prepared by the two step sintering and the spark plasma sintering (SPS) process. The successive transitions in nanograin BT ceramics from rhombohedrel to orthorhombic, tetragonal and cubic transitions, similar to those in coarse BT ceramics, were revealed by in-situ temperature dependent Raman spectrum. The multiphase coexistence and the diffused phase transition character were demonstrated in the 8 nm nanocrystalline BT ceramics.

  19. Microstructure and Performances of Nanocrystalline Zinc-nickel Alloy Coatings

    Institute of Scientific and Technical Information of China (English)

    LIGuang-yu; LIANJian-she; NIULi-yuan; JIANGZhong-hao

    2004-01-01

    Nanocrystalline zinc-nickel alloy coatings were deposited from an alkaline zincate bath contained an organic additive that can reduce polarization and a complexing agent. SEM and TEM observations and XRD analysis were performed to examine the microstructure and phase composition of the coatings. The nickel content in deposits is 12.0-14.7% and the coating is consisted of single nanectystalline γ-phase structure (Ni5Zn21), with grain average grain size about 15nm. The nanocrystalline zinc-nickel alloy coatings have better corrosion resistance, less brittleness and higher microhardness than the conventional zinc coatings.

  20. Nanocrystalline silicon prepared at high growth rate using helium dilution

    Indian Academy of Sciences (India)

    Koyel Bhattacharya; Debajyoti Das

    2008-06-01

    Growth and optimization of the nanocrystalline silicon (nc-Si : H) films have been studied by varying the electrical power applied to the helium diluted silane plasma in RF glow discharge. Wide optical gap and conducting intrinsic nanocrystalline silicon network of controlled crystalline volume fraction and oriented crystallographic lattice planes have been obtained at a reasonably high growth rate from helium diluted silane plasma, without using hydrogen. Improving crystallinity in the network comprising ∼ 10 nm Si-nanocrystallites and contributing optical gap widening, conductivity ascending and that obtained during simultaneous escalation of the deposition rate, promises significant technological impact.

  1. Preparation of nanocrystalline BaTiO3 ceramics

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The high-dense nanocrystalline BaTiO3(BT)ceramics with grain size smaller than 100nm have been successfully prepared by the two step sintering and the spark plasma sintering(SPS)process.The successive transitions in nanograin BT ceramics from rhombohedral to orthorhombic,tetragonal and cubic transitions,similar to those in coarse BT ceramics,were revealed by in-situ temperature dependent Raman spectrum.The multiphase coexistence and the diffused phase transition character were demonstrated in the 8nm nanocrystalline BT ceramics.

  2. A maximum in the strength of nanocrystalline copper

    DEFF Research Database (Denmark)

    Schiøtz, Jakob; Jacobsen, Karsten Wedel

    2003-01-01

    We used molecular dynamics simulations with system sizes up to 100 million atoms to simulate plastic deformation of nanocrystalline copper. By varying the grain size between 5 and 50 nanometers, we show that the flow stress and thus the strength exhibit a maximum at a grain size of 10 to 15...... nanometers. This maximum is because of a shift in the microscopic deformation mechanism from dislocation-mediated plasticity in the coarse-grained material to grain boundary sliding in the nanocrystalline region. The simulations allow us to observe the mechanisms behind the grain-size dependence...

  3. Molecular Dynamics Simulation of Microstructure of Nanocrystalline Copper

    Institute of Scientific and Technical Information of China (English)

    WEN Yu-Hua; ZHOU Fu-Xin; LIU Yue-Wu

    2001-01-01

    The microstructure of computer generated nanocrystalline coppers is simulated by using molecular dynamics with the Finnis-Sinclair potential, analysed by means of radial distribution functions, coordination number, atomic energy and local crystalline order. The influence of the grain size on the nanocrystalline structure is studied.The results reveal that as the grain size is reduced, the grain boundary shows no significant structural difference,but the grain interior becomes more disordered, and their structural difference diminishes gradually; however,the density and the atomic average energy of the grain boundary present different tendencies from those of the grain interior.

  4. Design of AlCrSiN multilayers and nanocomposite coating for HSS cutting tools

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Weiwei [School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan City, Anhui Province 243002 (China); Material Processing Research Department, Korea Institute of Materials Science (KIMS), 66 Sangnam-dong, Changwon, Kyungnam 641-010 (Korea, Republic of); Chen, Wanglin; Yang, Shubao; Lin, Yue [School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan City, Anhui Province 243002 (China); Zhang, Shihong, E-mail: shzhang@ahut.edu.cn [School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan City, Anhui Province 243002 (China); Cho, Tong-Yul [Institute of Industrial Technology, Changwon National University, Changwon, Kyungnam 641-773 (Korea, Republic of); Lee, G.H. [Material Processing Research Department, Korea Institute of Materials Science (KIMS), 66 Sangnam-dong, Changwon, Kyungnam 641-010 (Korea, Republic of); Kwon, Sik-Chol [School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan City, Anhui Province 243002 (China)

    2015-10-01

    Highlights: • Design of the AlCrSiN multilayer and composite coating. • Tribological/mechanical properties of the coatings. • AlCrSiN coating with the special structures presented lowest F.C. • AlCrSiN coating possessed best service life and cutting performance for the application of high-speed steel (HSS) tools. - Abstract: In the present work, AlCrN coating and AlCrSiN multilayer and nanocomposite coating were designed and deposited on the surface of high speed steel (HSS) cutters. The microstructures of these coatings were investigated systematically by means of grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscope (XPS), electron probe X-ray microanalysis (EPMA), scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM), in association with mechanical property measurement and corresponding cutting test. The results showed that the AlCrN coating mainly composed of nanocrystalline fcc-CrN, hcp-AlN and fcc-(Cr,Al)N solid-solution. In addition to these nanocrystalline phases, a few amorphous Si{sub 3}N{sub 4} phases were observed for the AlCrSiN multilayers and nanocomposite coating with a stronger {2 0 0} preferred orientation. The modulation period (6 nm) of the AlCrSiN coating was much smaller than that of the AlCrN coating (18 nm). The service life of the AlCrSiN coated tool increased approximately 40% longer in comparison with the AlCrN coated tool because of its more excellent mechanical properties (48 GPa hardness, 1123 MPa toughness, 52 N LC2 adhesion strength and 0.25 average friction coefficient). During the cutting process, the wear mechanisms of coated tools at the early stage and mid-stage were abrasion wear and adhesion wear, respectively. And the worn loss of AlCrSiN coated tool was less than that of AlCrN coated tool.

  5. Titania-coated manganite nanoparticles: Synthesis of the shell, characterization and MRI properties

    Science.gov (United States)

    Jirák, Zdeněk; Kuličková, Jarmila; Herynek, Vít; Maryško, Miroslav; Koktan, Jakub; Kaman, Ondřej

    2017-04-01

    Novel procedure for coating of oxide nanoparticles with titania, employing hydrolysis and polycondensation of titanium alkoxides under high-dilution conditions and cationic surfactants, is developed and applied to magnetic cores of perovskite manganite. Bare particles of the ferromagnetic La0.65Sr0.35MnO3 phase, possessing high magnetization, M10 kOe(4.5 K) = 63.5 emu g-1, and Curie temperature, TC = 355 K, are synthesized by sol-gel procedure and subsequently coated with titania. Further, a comparative silica-coated product is prepared. In order to analyse the morphology, colloidal stability, and surface properties of these two types of coated particles, a detailed study by means of transmission electron microscopy, dynamic light scattering, zeta-potential measurements, and IR spectroscopy is carried out. The experiments on the titania-coated sample reveal a continuous though porous character of the TiO2 shell, the nature of which is amorphous but can be transformed to anatase at higher temperatures. Finally, the relaxometric study at the magnetic field of 0.5 T, performed to quantity the transverse relaxivity and its temperature dependence, reveals important differences between the titania-coated and silica-coated nanoparticles.

  6. Climatic impacts of stratospheric geoengineering with sulfate, black carbon and titania injection

    Directory of Open Access Journals (Sweden)

    A. C. Jones

    2015-11-01

    Full Text Available In this paper, we examine the potential climatic effects of geoengineering by sulfate, black carbon and titania injection against a baseline RCP8.5 scenario. We use the HadGEM2-CCS model to simulate scenarios in which the top-of-the-atmosphere radiative imbalance due to rising greenhouse gas concentrations is offset by sufficient aerosol injection throughout the 2020–2100 period. We find that the global-mean temperature is effectively maintained at historical levels for the entirety of the period for all 3 aerosol-injection scenarios, though there are a wide range of side-effects which are discussed in detail. The most prominent conclusion is that although the BC injection rate necessary to produce an equivalent global mean temperature-response is much lower, the severity of stratospheric temperature changes (> +70 °C and precipitation impacts effectively exclude BC from being a viable option for geoengineering. Additionally, while it has been suggested that titania would be an effective particle because of its high scattering efficiency, it also efficiently absorbs solar ultraviolet radiation producing a significant stratospheric warming (> +20 °C. As injection rates for titania are close to those for sulfate, there appears little benefit of using titania when compared to injection of sulfur dioxide, which has the added benefit of being well modelled through extensive research that has been carried out on naturally occurring explosive volcanic eruptions.

  7. The Synthesis and Characterization of Titania Nanotubes Formed at Various Anodisation Time

    Science.gov (United States)

    Sreekantan, S.; Hung, L. M.; Lockman, Z.; Ahmad, Z. A.; Noor, A. F. Mohd

    2008-03-01

    One-dimensional (1D) nanostructured titania such as nanowires, nanorod and nanotubes have attracted considerable attention recently due to their unique physical properties and their potential application in water photoelectrolysis, photocatalysis, gas sensing, and photovoltaic. In this work, a simple anodisation method has been developed to fabricate titania nanotubes in 1M Na2SO4 containing various amount of NH4F. The dimension of the titania nanotube produced depend on the electrochemical process parameter: composition of the electrolyte, pH of the electrolyte and time of anodisation. As for this paper, the effect of fluoride content and anodisation time on the formation of titania nanotube was discussed in detail. The nanotubes formed were analyzed by field emission scanning electron microscope (FESEM) and X-Ray diffraction (XRD). The minimum fluoride content that is required to form nice well ordered nanotube for sample anodized for 30 minutes is 0.3g whereas for 120 minutes is 0.1g.

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

    Institute of Scientific and Technical Information of China (English)

    Bing Su; Guoqing Zhang; Xudong Yu; Chengtao Wang

    2006-01-01

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

  9. Characterization of Titania Incorporated with Alumina Nanocrystals and Their Impacts on Electrical Hysteresis and Photoluminescence

    Directory of Open Access Journals (Sweden)

    Shi Lei

    2009-01-01

    Full Text Available Abstract The structural and optical characterizations of titania incorporated with alumina nanocrystals have been presented in this paper and the films exhibit excellent properties like low current density, small hysteresis as well as high photoluminescence quantum yields of about 361 nm. These properties are promising for the applications in future electronic devices.

  10. Negative results of growing titania nanotubes on cellulose nanocrystals - Effect of hydrothermal reaction

    Science.gov (United States)

    Chamakh, Mariem Mohamed; Ponnamma, Deepalekshmi; Al-Maadeed, Mariam Al Ali

    Titania nanotubes (TiO2 nanotubes or TNT) are grown hydrothermally on cellulose nanocrystals (CNC) synthesized from microcrystalline cellulose. It is observed that the CNC are lost during synthesis due to its low thermal stability. This negative result of metal growth on CNC and its influence on thermal degradation are reported here.

  11. Textural evolution and phase transformation in titania membranes: Part 1. -unsupported membranes

    NARCIS (Netherlands)

    Kumar, Krishnankutty-Nair P.; Keizer, Klaas; Burggraaf, Anthonie J.

    1993-01-01

    Textural evolution in sol–gel derived nanostructured unsupported titania membranes has been studied using differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermal gravimetry (TG), X-ray diffraction (XRD) and N2 adsorption. The anatase-to-rutile phase transformation kinet

  12. Textural evolution and phase transformation in titania membranes: Part 2. - Supported membranes

    NARCIS (Netherlands)

    Kumar, Krishnankutty-Nair P.; Keizer, Klaas; Burggraaf, Anthonie J.; Okubo, Tatsuya; Nagamoto, Hidetoshi

    1993-01-01

    Nanostructural evolution and phase transformation in supported and unsupported titania membranes have been studied using Raman spectroscopy, X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Densification of unsupported membranes started at ca. 450 °C and reached more

  13. A Novel Synthesis of Titania-silica Mixed Oxide with Mesoporous Structure

    Institute of Scientific and Technical Information of China (English)

    Wei Ping HUANG; Hong LI; Bao Qing LI; Feng GAO; Xiu Chen ZHENG; Shou Min ZHANG; Shi Hua WU

    2004-01-01

    Mixture formed from sonicating TiCl4 and Si(OEt)4 in the absence of water is used as precursor and hydrolyzed by using a long-chain organic ammonium bromide as a structure-directing agent. The product, titania-silica, is of mesoporous structure and characterized with SEM, FT-IR, BET, XRD and so on.

  14. The Sulfidation of gamma-Alumina and Titania Supported (Cobalt) Molybdenum Oxide Catalysts Monitored by EXAFS.

    NARCIS (Netherlands)

    Koningsberger, D.C.; Leliveld, R.G.; Dillen, A.J. van; Geus, John W.

    1997-01-01

    The sulfidation of @c-alumina- and titania-supported(cobalt)molybdenum oxide catalysts has been studied with X-rayabsorption spectroscopy and temperature programmed sulfidation (TPS).The catalysts were stepwise sulfided at temperatures between 298 and673 K and their structure was determined with EXA

  15. Selective autooxidation of ethanol over titania-supported molybdenum oxide catalysts: structure and reactivity

    NARCIS (Netherlands)

    Caro, C.; Thirunavukkarasu, K.; Anilkumar, M.; Shiju, N.R.; Rothenberg, G.

    2012-01-01

    We study the selective catalytic oxidation of ethanol with air as a sustainable alternative route to acetaldehyde. The reaction is catalysed by molybdenum oxide supported on titania, in a flow reactor under ambient pressure. High selectivity to acetaldehyde (70%-89%, depending on the Mo loading) is

  16. Climatic impacts of stratospheric geoengineering with sulfate, black carbon and titania injection

    Science.gov (United States)

    Jones, Anthony C.; Haywood, James M.; Jones, Andy

    2016-03-01

    In this paper, we examine the potential climatic effects of geoengineering by sulfate, black carbon and titania injection against a baseline RCP8.5 scenario. We use the HadGEM2-CCS model to simulate scenarios in which the top-of-the-atmosphere radiative imbalance due to rising greenhouse gas concentrations is offset by sufficient aerosol injection throughout the 2020-2100 period. We find that the global-mean temperature is effectively maintained at historical levels for the entirety of the period for all three aerosol-injection scenarios, though there is a wide range of side-effects which are discussed in detail. The most prominent conclusion is that although the BC injection rate necessary to produce an equivalent global mean temperature response is much lower, the severity of stratospheric temperature changes (> +70 °C) and precipitation impacts effectively exclude BC from being a viable option for geoengineering. Additionally, while it has been suggested that titania would be an effective particle because of its high scattering efficiency, it also efficiently absorbs solar ultraviolet radiation producing a significant stratospheric warming (> +20 °C). As injection rates and climatic impacts for titania are close to those for sulfate, there appears to be little benefit in terms of climatic influence of using titania when compared to the injection of sulfur dioxide, which has the added benefit of being well-modeled through extensive research that has been carried out on naturally occurring explosive volcanic eruptions.

  17. Preparation of titania particles utilizing the insoluble phase interface in a microchannel reactor.

    Science.gov (United States)

    Wang, Hongzhi; Nakamura, Hiroyuki; Uehara, Masato; Miyazaki, Masaya; Maeda, Hideaki

    2002-07-21

    A stable interface between two insoluble currents in a microchannel reactor has been obtained by selecting the solvents and adjusting the flow rate; titania particles with a size of less than 10 nm could be prepared continuously on this interface; this new method shows great advantage for the control and measurement of particle sizes.

  18. Oxidations of amines with molecular oxygen using bifunctional gold–titania catalysts

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; Egeblad, Kresten; Mentzel, Uffe Vie

    2008-01-01

    Over the past decades it has become clear that supported gold nanoparticles are surprisingly active and selective catalysts for several green oxidation reactions of oxygen-containing hydrocarbons using molecular oxygen as the stoichiometric oxidant. We here report that bifunctional gold–titania c...... new and environmentally benign routes to caprolactam and cyclohexanone oxime, both of which are precursors for nylon-6....

  19. Primary role of electron work function for evaluation of nanostructured titania implant surface against bacterial infection.

    Science.gov (United States)

    Golda-Cepa, M; Syrek, K; Brzychczy-Wloch, M; Sulka, G D; Kotarba, A

    2016-09-01

    The electron work function as an essential descriptor for the evaluation of metal implant surfaces against bacterial infection is identified for the first time. Its validity is demonstrated on Staphylococcus aureus adhesion to nanostructured titania surfaces. The established correlation: work function-bacteria adhesion is of general importance since it can be used for direct evaluation of any electrically conductive implant surfaces.

  20. Bactericidal performance of visible-light responsive titania photocatalyst with silver nanostructures.

    Directory of Open Access Journals (Sweden)

    Ming-Show Wong

    Full Text Available BACKGROUND: Titania dioxide (TiO(2 photocatalyst is primarily induced by ultraviolet light irradiation. Visible-light responsive anion-doped TiO(2 photocatalysts contain higher quantum efficiency under sunlight and can be used safely in indoor settings without exposing to biohazardous ultraviolet light. The antibacterial efficiency, however, remains to be further improved. METHODOLOGY/PRINCIPAL FINDINGS: Using thermal reduction method, here we synthesized silver-nanostructures coated TiO(2 thin films that contain a high visible-light responsive antibacterial property. Among our tested titania substrates including TiO(2, carbon-doped TiO(2 [TiO(2 (C] and nitrogen-doped TiO(2 [TiO(2 (N], TiO(2 (N showed the best performance after silver coating. The synergistic antibacterial effect results approximately 5 log reductions of surviving bacteria of Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus and Acinetobacter baumannii. Scanning electron microscope analysis indicated that crystalline silver formed unique wire-like nanostructures on TiO(2 (N substrates, while formed relatively straight and thicker rod-shaped precipitates on the other two titania materials. CONCLUSION/SIGNIFICANCE: Our results suggested that proper forms of silver on various titania materials could further influence the bactericidal property.

  1. Evaluation of antimicrobial efficacy of nano coated silver-titania metallic plates against selective pathogens

    Directory of Open Access Journals (Sweden)

    Mohamad, S.M.

    2012-01-01

    Full Text Available Aim: Nanotechnology is an increasingly growing field with its current application in Science and Technology for the purpose of manufacture of novel materials at the nanoscale level. Silver-Titania nanoparticles (AgTiO2-NPs have been known to have inhibitory and bactericidal effects.Methodology and Results: In the present study, stable silver-titania nanoparticles coated metallic blocks were prepared for testing their efficacy against selected bacterial pathogens like Escherichia coli and Staphylococcus aureus. In the experimental part, the bacterial pathogens were inoculated on silver-titania nanoparticle coated blocks and the treatment was carried out in „0‟ time and „24‟ h interval and were enumerated.Conclusion, significance and impact of study:The results were compared with the control (uncoated metallic blocks and analyzed by using Japanese Industrial Standard (JIS Z2801:2000 method. From this study, it was concluded that silver-titania nanoparticles has inhibitory effect on bacterial pathogen tested.

  2. NANOSIZE TITANIA STIMULATES REACTIVE OXYGEN SPECIES IN BRAIN MICROGLIA AND DAMAGES NEURONS.

    Science.gov (United States)

    Research that addresses the environmental impact and biological consequences of widely distributed, commonly used nanoparticles is needed. Nanosize titanium dioxide (i.e., titania, TiO2) is used in air and water remediation and in numerous products designed for direct human us...

  3. Immobilization in cement mortar of chromium removed from water using titania nanoparticles.

    Science.gov (United States)

    Husnain, Ahmed; Qazi, Ishtiaq Ahmed; Khaliq, Wasim; Arshad, Muhammad

    2016-05-01

    Because of the high toxicity of chromium, particularly as Cr (VI), it is removed from industrial effluents before their discharge into water bodies by a variety of techniques, including adsorption. Ultimate disposal of the sludge or the adsorbate, however, is a serious problem. While titania, in nanoparticle form, serves as a very good adsorbent for chromium, as an additive, it also helps to increase the compressive strength of mortar and concrete. Combining these two properties of the material, titania nanoparticles were used to adsorb chromium and then added to mortar up to a concentration of 20% by weight. The compressive strength of the resulting mortar specimens that replaced 15% of cement with chromium laden titania showed an improved strength than that without titania, thus confirming that this material had positive effect on the mortar strength. Leachate tests using the Toxicity Characteristics Leaching Procedure (TCLP) confirmed that the mortar sample chromium leachate was well within the permissible limits. The proposed technique thus offers a safe and viable method for the ultimate disposal of toxic metal wastes, in general, and those laden waste chromium, in particular.

  4. Hazard reduction for the application of titania nanoparticles in environmental technology

    NARCIS (Netherlands)

    L. Reijnders

    2008-01-01

    Photocatalytically active titania (TiO2) nanoparticles are applied, and considered for application, in the degradation of hazardous substances. However, these nanoparticles are also hazardous by themselves. High efficiency immobilization of TiO2 nanoparticles on large inorganic supports that are not

  5. Controlling the morphology of thin titania films for applications in hybrid solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rawolle, Monika; Ruderer, Matthias A.; Prams, Stefan; Zhong, Qi; Mueller-Buschbaum, Peter [TU Muenchen, Physik-Department LS E13, Garching (Germany); Memesa, Mine; Gutmann, Jochen S. [Max-Planck Institute for Polymer Research, Mainz (Germany)

    2010-07-01

    Nanostructured thin films of titania have a variety of applications. For applications in photovoltaics a high absorption coefficient and a large surface area are desirable. A sponge structure is a promising morphology for titania to meet these demands. Block copolymers can be used in a good-poor solvent pair induced phase separation process coupled with sol-gel chemistry to create structured titania films in a reproducible way. We use the amphiphilic diblock copolymer Poly(dimethyl siloxane)-block-methyl methacrylate poly(ethylene oxide)[PDMS-b-MA(PEO)] as templating agent. Different well defined mixing procedures of sol-gel components (Tetrahydrofuran, 2-Propanol, HCl and titania precursor in addition to the PDMS-b-MA(PEO)) of same weight fractions result in small changes in the morphology of the film. The thin films are prepared via spin-coating on silicon substrates. The surface structure is studied with SEM. Information on the morphology in the volume of the film is gained from GISAXS. The layer thickness and structure are studied with XRR, the optical properties with UV/Vis spectroscopy.

  6. Selective photocatalytic degradation of aquatic pollutants by titania encapsulated into FAU-type zeolites.

    Science.gov (United States)

    Zhang, Guan; Choi, Wonyong; Kim, Seok Han; Hong, Suk Bong

    2011-04-15

    The selective photocatalytic degradation of charged pollutants in water was achieved on titania encapsulated into FAU-type zeolites. The electrostatic attraction of cationic substrates and repulsion of anionic substrates by the negatively charged zeolite framework facilitated the selective photocatalytic degradation of charged substrates. The hybrid zeolite-titania photocatalysts were prepared through the ion-exchange method. The titania clusters were mainly well distributed within the cavities of FAU-type zeolites whereas no TiO(2) nanoparticles aggregates were observed on the external surface of zeolite crystals. The hybrid zeolite-titania photocatalysts were characterized by diffuse reflectance UV-visible spectroscopy, transmission electron microscopy, energy-dispersive X-ray analysis and X-ray photoelectron spectroscopy. The selective degradation of charged pollutants was investigated by employing three pairs of oppositely charged substrates. The comparison between the cationic and anionic substrates clearly showed that the degradation rates for the cationic substrates on the hybrid photocatalysts are markedly higher than those for the anionic substrates. Among the cationic substrates, the smaller cations such as tetramethylammoniums were preferentially degraded. This enabled the selective removal of cationic substrates among the mixture. Such a selective photocatalytic degradation of water pollutants may provide a useful strategy for the development of economical photocatalytic process by targeting only the most recalcitrant pollutant.

  7. Polyelectrolyte Multilayers: Towards Single Cell Studies

    Directory of Open Access Journals (Sweden)

    Dmitry Volodkin

    2014-05-01

    Full Text Available Single cell analysis (SCA is nowadays recognized as one of the key tools for diagnostics and fundamental cell biology studies. The Layer-by-layer (LbL polyelectrolyte assembly is a rather new but powerful technique to produce multilayers. It allows to model the extracellular matrix in terms of its chemical and physical properties. Utilization of the multilayers for SCA may open new avenues in SCA because of the triple role of the multilayer film: (i high capacity for various biomolecules; (ii natural mimics of signal molecule diffusion to a cell and (iii cell patterning opportunities. Besides, light-triggered release from multilayer films offers a way to deliver biomolecules with high spatio-temporal resolution. Here we review recent works showing strong potential to use multilayers for SCA and address accordingly the following issues: biomolecule loading, cell patterning, and light-triggered release.

  8. Multilayer Nanoporous Graphene Membranes for Water Desalination.

    Science.gov (United States)

    Cohen-Tanugi, David; Lin, Li-Chiang; Grossman, Jeffrey C

    2016-02-10

    While single-layer nanoporous graphene (NPG) has shown promise as a reverse osmosis (RO) desalination membrane, multilayer graphene membranes can be synthesized more economically than the single-layer material. In this work, we build upon the knowledge gained to date toward single-layer graphene to explore how multilayer NPG might serve as a RO membrane in water desalination using classical molecular dynamic simulations. We show that, while multilayer NPG exhibits similarly promising desalination properties to single-layer membranes, their separation performance can be designed by manipulating various configurational variables in the multilayer case. This work establishes an atomic-level understanding of the effects of additional NPG layers, layer separation, and pore alignment on desalination performance, providing useful guidelines for the design of multilayer NPG membranes.

  9. Figure correction of multilayer coated optics

    Science.gov (United States)

    Chapman; Henry N. , Taylor; John S.

    2010-02-16

    A process is provided for producing near-perfect optical surfaces, for EUV and soft-x-ray optics. The method involves polishing or otherwise figuring the multilayer coating that has been deposited on an optical substrate, in order to correct for errors in the figure of the substrate and coating. A method such as ion-beam milling is used to remove material from the multilayer coating by an amount that varies in a specified way across the substrate. The phase of the EUV light that is reflected from the multilayer will be affected by the amount of multilayer material removed, but this effect will be reduced by a factor of 1-n as compared with height variations of the substrate, where n is the average refractive index of the multilayer.

  10. Synthesis of titania thin films with controlled mesopore orientation: Nanostructure for energy conversion and storage

    Science.gov (United States)

    Nagpure, Suraj R.

    This dissertation addresses the synthesis mechanism of mesoporous titania thin films with 2D Hexagonal Close Packed (HCP) cylindrical nanopores by an evaporation-induced self-assembly (EISA) method with Pluronic surfactants P123 and F127 as structure directing agents, and their applications in photovoltaics and lithium ion batteries. To provide orthogonal alignment of the pores, surface modification of substrates with crosslinked surfactant has been used to provide a chemically neutral surface. GISAXS studies show not only that aging at 4 °C facilitates ordered mesostructure development, but also that aging at this temperature helps to provide orthogonal orientation of the cylindrical micelles which assemble into an ordered mesophase directly by a disorder-order transition. These films provide pores with 8-9 nm diameter, which is precisely the structure expected to provide short carrier diffusion length and high hole conductivity required for efficient bulk heterojunction solar cells. In addition, anatase titania is a n-type semiconductor with a band gap of +3.2 eV. Therefore, titania readily absorbs UV light with a wavelength below 387 nm. Because of this, these titania films can be used as window layers with a p-type semiconductor incorporated into the pores and at the top surface of the device to synthesize a photovoltaic cell. The pores provide opportunities to increase the surface area for contact between the two semiconductors, to align a p-type semiconductor at the junction, and to induce quantum confinement effects. These titania films with hexagonal phase are infiltrated with a hole conducting polymer, poly(3-hexylthiophene) (P3HT), in order to create a p-n junctions for organic-inorganic hybrid solar cells, by spin coating followed by thermal annealing. This assembly is hypothesized to give better photovoltaic performance compared to disordered or bicontinuous cubic nanopore arrangements; confinement in cylindrical nanopores is expected to provide

  11. Physicochemical characterization of functionalized-nanostructured-titania as a carrier of copper complexes for cancer treatment

    Energy Technology Data Exchange (ETDEWEB)

    López, Tessy [Nanotechnology and Nanomedicine Laboratory, Metropolitan Autonomous University-Xochimilco, Calzada del Hueso 1100, Villa Quietud, Coyoacán, 04960 México D.F. (Mexico); Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Department of Chemical and Biomolecular Engineering, Tulane University, 6823 St. Charles Avenue, New Orleans (United States); Ortiz, Emma, E-mail: emma170@hotmail.com [Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Guevara, Patricia [Neuroimmunology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Gómez, Esteban [Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Novaro, Octavio [Institute of Physics-UNAM, Circuito de la Investigación Científica Ciudad Universitaria, CP 04510 México D.F. (Mexico)

    2014-07-01

    In the present paper we report the preparation and characterization of functionalized-TiO{sub 2} (F-TiO{sub 2}) to obtain a biocompatible material to be used as carrier of alternative anticancer agents: copper acetate and copper acetylacetonate. The sol–gel procedure was used to prepare the fuctionalized titania material through hydrolysis and condensation of the titanium's butoxide. Sulfate, amine and phosphate ions served as functional groups which were anchored to the titania's surface. Mineral acids and gamma amine butyric acid were the precursors and they were added at the initial step of the synthesis. The copper complexes were loaded on titania and were also added to the reactor synthesis from the beginning. Infrared and ultraviolet–visible spectroscopies were the principal techniques used to the characterization of F-TiO{sub 2} and copper complexes loaded on titania materials. Transmission Electronic Microscopy (TEM) was used to complement the characterization's studies. The biocompatibility of F-TiO{sub 2} was evaluated by treating different cancer cell lines with increased concentration of this compound. The amine, the sulfate and the phosphate on the titania's surface, as well as the integral structures of the metal complexes on titania were well identified by infrared and ultraviolet–visible spectroscopies. The TEM photographs of Cu(acac){sub 2}/F-TiO{sub 2} and Cu(Oac){sub 2}/F-TiO{sub 2} materials showed the formation of nanoparticles, which have sizes ranging from 4 to 10 nm, with no morphology alterations in comparison with F-TiO{sub 2} nanoparticles, suggesting that the presence of low quantities of copper do not affect the structure of the nanoparticles. The Energy Dispersive Spectroscopy (EDS) confirms the presence of copper on the titania's nanoparticles. The biological results indicate that there is more than 90% cell survival, thus suggesting that F-TiO{sub 2} does not cause damage to the cells. Therefore

  12. Controlled release of phenytoin for epilepsy treatment from titania and silica based materials

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Tessy, E-mail: tessy3@prodigy.net.mx [Universidad Autonoma Metropolitana-Xochimilco. Departamento de Microbiologia. Calzada del Hueso 1100, Col. Villa Quietud, Coyoacan, C.P. 04960, Mexico D.F. Mexico (Mexico); Instituto Nacional de Neurologia y Neurocirugia ' MVS' . Laboratorio de Nanotecnologia. Av. Insurgentes Sur 3877, Col. La Fama, Tlalpan, 14269, Mexico, D.F. Mexico (Mexico); Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118 (United States); Ortiz, Emma [Instituto Nacional de Neurologia y Neurocirugia ' MVS' . Laboratorio de Nanotecnologia. Av. Insurgentes Sur 3877, Col. La Fama, Tlalpan, 14269, Mexico, D.F. Mexico (Mexico); Meza, Doraliz [Universidad Autonoma Metropolitana-Iztapalapa, Departamento de Quimica, Av. San Rafael Atlixco 186, A.P. 55-534, Mexico D.F., C.P. 09340 (Mexico); Basaldella, Elena [CIC-CINDECA - Universidad Nacional de La Plata - Calle 47 No 257 - La Plata (Argentina); Bokhimi, Xim; Magana, Carlos [Instituto de fisica, UNAM. Circuito de la Investigacion s/n. C.U. Mexico D.F. 01000 (Mexico); Sepulveda, Antonio; Rodriguez, Francisco; Ruiz, Javier [Departamento de Quimica Inorganica, Universidad de Alicante. Apartado 99, E-03080 Alicante, Espana Spain (Spain)

    2011-04-15

    Research highlights: {yields} Template technique was used to obtain well ordered nanostructured materials: SBA-15 and titania tubes. {yields} Phenytoin (PH), a drug used in epilepsy treatment, was loaded in these materials to used como PH release. {yields} Loaded PH showed a good stability inside the used materials as observed by spectroscopy analysis. {yields} The load-release PH are faster in nanostructured TiO2 tubes than in mesoporous silica matrix. {yields} There is an inverse effect of the surface area of the structured materials on the amount of released PH. - Abstract: Template technique was used to obtain well ordered nanostructured materials: mesoporous silica and nanostructured titania tubes. This technique permits the synthesis of solids with controlled mesoporosity, where a large variety of molecules that have therapeutic activity can be hosted and further released to specific sites. In this work phenytoin (PH), a drug used in epilepsy treatment, was loaded in ordered mesoporous silica (SBA 15) and nanostructured titania tubes (TiO{sub 2}). The pure materials and those containing PH were characterized by X-ray diffraction, FTIR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N{sub 2} adsorption-desorption at 77 K. In order to determine the loading capacity of the antiepileptic drug on these silica- and titania-based materials, the loading and release of PH was investigated using UV-vis spectroscopy. Tubular structures were found for the titania samples, for which the X-ray diffractograms showed to be formed by anatase and rutile phases. On the other hand, an amorphous phase was found in the silica sample. A highly ordered hexagonal structure of 1D cylindrical channels was also observed for this material. Loaded PH showed a good stability inside the used materials as observed by spectroscopy analysis. The adsorption and desorption of PH are faster in nanostructured TiO{sub 2} tubes than in mesoporous silica

  13. Homogeneously embedded Pt nanoclusters on amorphous titania matrix as highly efficient visible light active photocatalyst material

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Vipul; Kumar, Suneel; Krishnan, Venkata, E-mail: vkn@iitmandi.ac.in

    2016-08-15

    A novel and facile technique, based on colloidal synthesis route, has been utilized for the preparation of homogeneously embedded Pt nanoclusters on amorphous titania matrix. The material has been thoroughly characterized using high resolution transmission electron microscopy, energy dispersive x-ray analysis, powder x-ray diffraction, optical and Raman spectroscopic techniques to understand the morphology, structure and other physical characteristics. The photocatalytic activity of the material under visible light irradiation was demonstrated by investigations on the degradation of two organic dyes (methylene blue and rhodamine B). In comparison to other Pt−TiO{sub 2} based nanomaterials (core-shell, doped nanostructures, modified nanotubes, decorated nanospheres and binary nanocomposites), the embedded Pt nanoclusters on titania was found to be highly efficient for visible light active photocatalytic applications. The enhanced catalytic performance could be attributed to the efficient charge separation and decreased recombination of the photo generated electrons and holes at the Pt-titania interface and the availability of multiple metal-metal oxide interfaces due to homogeneous embedment of Pt nanoclusters on amorphous titania. In essence, this work illustrates that homogeneous embedment of noble metal nanoparticles/nanoclusters on semiconductor metal oxide matrices can lead to tuning of the photophysical properties of the final material and eventually enhance its photocatalytic activity. - Highlights: • Homogeneously embedded Pt nanoclusters on amorphous titania matrix has been prepared. • Facile low temperature colloidal synthesis technique has been used. • Enhanced catalytic performance could be observed. • Work can pave way for tuning photocatalytic activity of composite materials.

  14. Fabrication and characterization of nanostructured titania films with integrated function from inorganic-organic hybrid materials.

    Science.gov (United States)

    Rawolle, Monika; Niedermeier, Martin A; Kaune, Gunar; Perlich, Jan; Lellig, Philipp; Memesa, Mine; Cheng, Ya-Jun; Gutmann, Jochen S; Müller-Buschbaum, Peter

    2012-08-07

    Nanostructured titania films are of growing interest due to their application in future photovoltaic technologies. Therefore, a lot of effort has been put into the controlled fabrication and tailoring of titania nanostructures. The controlled sol-gel synthesis of titania, in particular in combination with block copolymer templates, is very promising because of its high control on the nanostructure, easy application and cheap processing possibilities. This tutorial review gives a short overview of the structural control of titania films gained by using templated sol-gel chemistry and shows how this approach is extended by the addition of further functionality to the films. Different expansions of the sol-gel templating are possible by the fabrication of gradient samples, by the addition of a homopolymer, by the combination with micro-fluidics and also by the application of novel precursors for low-temperature processing. Moreover, hierarchically structured titania films can be fabricated via the subsequent application of several sol-gel steps or via the inclusion of colloidal templates in a one-step process. Integrated function in the block copolymer used in the sol-gel synthesis allows for the fabrication of an integrated blocking layer or an integrated hole-conductor. Both approaches grant a one-step fabrication of two components of a working solar cell, which make them very promising towards a cheap solar cell production route. Looking to the complete solar cell, the top contact is also of great importance as it influences the function of the whole solar cell. Thus, the mechanisms acting in the top contact formation are also reviewed. For all these aspects, characterization techniques that allow for a structural investigation of nanostructures inside the active layers are important. Therefore, the characterization techniques that are used in real space as well as in reciprocal space are explained shortly as well.

  15. Hafnia-rich mixed oxide ceramics of the system HfO2-ZrO2-TiO2 for heaters and heat exchangers in electrothermal thrusters: The effects of titania on selected electrical and mechanical properties of Hafnia-rich mixed oxides in the system Hafnia-Zirconia-Titania, volume 1

    Science.gov (United States)

    Staszak, Paul Russell; Wirtz, G. P.; Berg, M.; Brown, S. D.

    1988-01-01

    A study of the effects of titania on selected properties of hafnia-rich mixed oxides in the system hafnia-zirconia-titania (HZT) was made in the region 5 to 20 mol percent titania. The studied properties included electrical conductivity, thermal expansion, and fracture strength and toughness. The effects of titania on the properties were studied for the reduced state as well as the oxidized state of the sintered mixed oxides. X-ray analysis showed that the materials were not always single phase. The oxidized compositions went from being monoclinic solid solutions at low titania additions to having three phases (two monoclinic and a titanate phase) at high additions of titania. The reduced compositions showed an increasing cubic phase presence mixed with the monoclinic phase as titania was added. The electrical conductivity increased with temperature at approximately 0.1 mhos/cm at 1700 C for all compositions. The thermal expansion coefficient decreased with increasing titania as did the monoclinic to tetragonal transformation temperature. The fracture strength of the oxidized bars tended to decrease with the addition of titania owing to the presence of the second phase titania. The fracture strength of the reduced bars exhibited a minimum corresponding to a two-phase region of monoclinic and cubic phases. When the second phases were suppressed, the titania tended to increase the fracture strength slightly in both the oxidized and reduced states. The fracture toughness followed similar trends.

  16. Nanocrystalline Pentaerythritoltetranitrate using Sol-Gel Process

    Directory of Open Access Journals (Sweden)

    Sanjay Vishwasrao Ingale

    2011-10-01

    Full Text Available The secondary explosives developed with reduced particle size tend to be more insensitive for mechanical stimuli and may release energy with faster rate and gaining more importance nowadays. Therefore, aiming to reduce the particle size of one of the popular explosives, viz., pentaerythritoltetranitrate (PETN to the nanometer range, a method for preparation of nanocrystalline PETN in the silica (SiO2 gel matrix using sol-gel process has been demonstrated. The PETN-SiO2 xerogels were prepared containing PETN content ranging from 50 per cent to 90 per cent (w/w and the xerogels were characterised using different techniques. An exothermic peak at around 185 oC preceded by an endotherm in thermal analysis accompanied with weight loss in the temperature range from 150 oC to 200 oC   for the xerogel confirmed the presence of PETN in xerogel. Infrared spectra of xerogels showed peaks at around 1285 cm-1 and 1700 cm-1 assigned to O-NO2 and C-O bond representing PETN. Small angle x-ray scattering measurements on xerogels indicated that PETN entered in the pores of silica matrix. Transmission electron microscopy revealed that cystalline PETN    with particle size of around 15 nm dispersed in silica xerogel. The specific surface area for the PETN-SiO2 (90:10 xerogels was found to be 75 m2/g.Defence Science Journal, 2011, 61(6, pp.534-539, DOI:http://dx.doi.org/10.14429/dsj.61.594

  17. Copper removal using electrosterically stabilized nanocrystalline cellulose.

    Science.gov (United States)

    Sheikhi, Amir; Safari, Salman; Yang, Han; van de Ven, Theo G M

    2015-06-03

    Removal of heavy metal ions such as copper using an efficient and low-cost method with low ecological footprint is a critical process in wastewater treatment, which can be achieved in a liquid phase using nanoadsorbents such as inorganic nanoparticles. Recently, attention has turned toward developing sustainable and environmentally friendly nanoadsorbents to remove heavy metal ions from aqueous media. Electrosterically stabilized nanocrystalline cellulose (ENCC), which can be prepared from wood fibers through periodate/chlorite oxidation, has been shown to have a high charge content and colloidal stability. Here, we show that ENCC scavenges copper ions by different mechanisms depending on the ion concentration. When the Cu(II) concentration is low (C0≲200 ppm), agglomerates of starlike ENCC particles appear, which are broken into individual starlike entities by shear and Brownian motion, as evidenced by photometric dispersion analysis, dynamic light scattering, and transmission electron microscopy. On the other hand, at higher copper concentrations, the aggregate morphology changes from starlike to raftlike, which is probably due to the collapse of protruding dicarboxylic cellulose (DCC) chains and ENCC charge neutralization by copper adsorption. Such raftlike structures result from head-to-head and lateral aggregation of neutralized ENCCs as confirmed by transmission electron microscopy. As opposed to starlike aggregates, the raftlike structures grow gradually and are prone to sedimentation at copper concentrations C0≳500 ppm, which eliminates a costly separation step in wastewater treatment processes. Moreover, a copper removal capacity of ∼185 mg g(-1) was achieved thanks to the highly charged DCC polyanions protruding from ENCC. These properties along with the biorenewability make ENCC a promising candidate for wastewater treatment, in which fast, facile, and low-cost removal of heavy metal ions is desired most.

  18. Structural, magnetic and dielectric studies of copper substituted nano-crystalline spinel magnesium zinc ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Zaki, H.M., E-mail: dakdik2001@yahoo.com [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Department of Physics, Faculty of Science, Zagazig University, Zagazig (Egypt); Al-Heniti, S.H. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Elmosalami, T.A. [Department of Physics, Faculty of Science, Zagazig University, Zagazig (Egypt)

    2015-06-05

    Highlights: • Nano ferrite Mg{sub 0.5}Zn{sub 0.5−x}Cu{sub x}Fe{sub 2}O{sub 4} were prepared through co-precipitation route. • Structural investigations of XRD and FTIR revealed formation of spinel structure. • Lattice constant decrease while saturation magnetization increase. • Correlated barrier-hopping (CBH) is the dominant conduction mechanism. • Dielectric properties make sample appropriate for multilayer inductor applications. - Abstract: Nano-crystalline Mg{sub 0.5}Zn{sub 0.5−x}Cu{sub x}Fe{sub 2}O{sub 4} (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) ferrite powders were synthesized using co-precipitation method. The influence of Cu{sup 2+} ions substitution on the structural and magnetic properties was investigated. X-ray diffraction measurements revealed the formation of nano-crystalline ferrite with single cubic spinel phase. The lattice constant was found to decrease with increasing Cu{sup 2+} ions content. Infrared spectral analysis confirmed formation of the spinel structure for the respective ferrite system. Magnetic data showed that the saturation magnetization (M{sub s}) increases with Cu{sup 2+} concentration up to x = 0.2 and then decreases with further increase of Cu{sup 2+} ions in this ferrite system. The proposed cation distribution deduced from X-ray diffraction, infrared spectra and magnetization data indicated mixed ferrite type. Dielectric constants ε′, dielectric loss ε′′, dielectric loss tangent tan δ and ac conductivity, σ{sub ac}, were investigated as a function of frequency and temperature. Influence of Cu{sup 2+} substation on the ac conductivity exhibited significant behavior at low frequencies and low temperatures, T ⩽ 100 °C. Both dielectric constants (ε′, ε″) found to increase with the increase of the temperature. At low temperatures, dielectric loss tan δ indicated a decrease with frequency with slight change at high temperatures.

  19. SERS activity of self-cleaning silver/titania nanoarray

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yibing, E-mail: ybxie@seu.edu.cn [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Suzhou Research Institute of Southeast University, Suzhou 215123 (China); Jin, Yanyan [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Suzhou Research Institute of Southeast University, Suzhou 215123 (China); Zhou, Yingzhi; Wang, Yong [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China)

    2014-09-15

    Highlights: • Ag/TiO{sub 2} nanoarray is prepared by depositing Ag on TiO{sub 2} nanorod and nanotube array. • Ag/TiO{sub 2} nanoarray shows good SERS activity and self-cleaning performance as well. • Ag/TiO{sub 2} NRA as SERS substrate shows a low detection limit of PMBA below 5 × 10{sup −12} M. - Abstract: Silver decorated titania nanorod array (Ag/TiO{sub 2} NRA) and nanopore array (Ag/TiO{sub 2} NPA) had been designed as surface-enhanced Raman scattering (SERS) active substrate for a sensitive detection application. TiO{sub 2} NRA grown on glass slide was fabricated through hydrothermal synthesis process. TiO{sub 2} NPA grown on the titanium sheet was fabricated by a two-stepped anodization process. Ag/TiO{sub 2} NRA and Ag/TiO{sub 2} NPA were formed by depositing silver nanoparticles on TiO{sub 2} nanoarray through an electroless deposition process. Ag/TiO{sub 2} NRA had smaller silver interparticle gaps and more hot-spots than Ag/TiO{sub 2} NPA, exhibiting a higher SERS activity. The analytical enhancement factor was accordingly increased from 1.8 × 10{sup 5} for Ag/TiO{sub 2} NPA up to 7.8 × 10{sup 5} for Ag/TiO{sub 2} NRA. Ag/TiO{sub 2} NRA substrate achieved a very low detection limit of 5 × 10{sup −12} M 4-mercaptobenzoic acid as a probe molecule, showing a sensitive SERS detection performance. Ag/TiO{sub 2} NRA also conducted photocatalysis decomposition of these adsorbed organic molecules to recover a clean surface under UV irradiation, exhibiting a self-cleaning activity. Such an Ag/TiO{sub 2} nanoarray with well-controlled size and shape could be suitably applies as a self-cleaning SERS substrate, showing high reproducibility and cycleability in recycling SERS detection application.

  20. A one-pot method to prepare N-doped titania hollow spheres with high photocatalytic activity under visible light

    Science.gov (United States)

    Ao, Yanhui; Xu, Jingjing; Zhang, Songhe; Fu, Degang

    2010-02-01

    N-doped titania hollow spheres (NTHS) were prepared by a one-pot hydrothermal method using urea as precursor of nitrogen. The prepared hollow spheres were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectrum (DRS). The photocatalytic activity of as-prepared titania hollow spheres was determined by degradation of Reactive Brilliant Red dye X-3B (C.I. reactive red 2) under visible light irradiation, and was compared to non-doped titania hollow spheres and commercial P25 titania. Results indicated that the as-prepared NTHS showed highest photocatalytic activity.

  1. In situ formation of titania film on NiTi alloy treated with hydrogen peroxide solution at low temperature

    Institute of Scientific and Technical Information of China (English)

    CHU Cheng-lin; ZHOU Jun; CHUNG Jonathan-CY; PU Yao-pu; LUN Ping-hua

    2005-01-01

    Chemically polished NiTi shape memory alloy(SMA) substrate was treated with a boiling aqueous solution containing hydrogen peroxide to form titania film in situ at low temperature. The surface characterizations of titania film on NiTi substrate were investigated by scanning electron microscopy, X-ray diffractometry and X-ray photoelectron spectroscopy. The results show that titania film is successfully fabricated in situ on NiTi SMA by this surface oxidation method. It is mainly composed of rutile and anatase, whose surface compositions and morphologies are sensitive to H2O2 content. In situ formation mechanism of titania film on NiTi substrate was discussed based on the experimental results.

  2. High deposition rate nanocrystalline silicon with enhanced homogeneity

    NARCIS (Netherlands)

    Verkerk, A.; Rath, J.K.; Schropp, R.E.I.

    2010-01-01

    High rate growth of hydrogenated nanocrystalline silicon (nc-Si:H) brings additional challenges for the homogeneity in the growth direction, since the start-up effects affect a larger portion of the film, and the very high degree of depletion increases the influence of back diffusion from the inacti

  3. A new approach to grain boundary engineering for nanocrystalline materials

    Directory of Open Access Journals (Sweden)

    Shigeaki Kobayashi

    2016-11-01

    Full Text Available A new approach to grain boundary engineering (GBE for high performance nanocrystalline materials, especially those produced by electrodeposition and sputtering, is discussed on the basis of some important findings from recently available results on GBE for nanocrystalline materials. In order to optimize their utility, the beneficial effects of grain boundary microstructures have been seriously considered according to the almost established approach to GBE. This approach has been increasingly recognized for the development of high performance nanocrystalline materials with an extremely high density of grain boundaries and triple junctions. The effectiveness of precisely controlled grain boundary microstructures (quantitatively characterized by the grain boundary character distribution (GBCD and grain boundary connectivity associated with triple junctions has been revealed for recent achievements in the enhancement of grain boundary strengthening, hardness, and the control of segregation-induced intergranular brittleness and intergranular fatigue fracture in electrodeposited nickel and nickel alloys with initial submicrometer-grained structure. A new approach to GBE based on fractal analysis of grain boundary connectivity is proposed to produce high performance nanocrystalline or submicrometer-grained materials with desirable mechanical properties such as enhanced fracture resistance. Finally, the potential power of GBE is demonstrated for high performance functional materials like gold thin films through precise control of electrical resistance based on the fractal analysis of the grain boundary microstructure.

  4. Electrodeposited nanocrystalline bronze alloys as replacement for Ni

    NARCIS (Netherlands)

    Hovestad, A.; Tacken, R.A.; Mannetje, H.H.'t

    2008-01-01

    Nanocrystalline white-bronze, CuSn, electroplating was investigated as alternative to Ni plating as undercoat for noble metals in jewellery applications. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. Polarization curv

  5. Development of a Nanocrystalline Paclitaxel Formulation for Hipec Treatment

    NARCIS (Netherlands)

    De Smet, Lieselotte; Colin, Pieter; Ceelen, Wim; Bracke, Marc; Van Bocxlaer, Jan; Remon, Jean Paul; Vervaet, Chris

    2012-01-01

    To develop a nanocrystalline paclitaxel formulation with a high paclitaxel-to-stabilizer ratio which can be used for hyperthermic intraperitoneal chemotherapy (HIPEC). Paclitaxel (PTX) nanocrystals were prepared via wet milling using Pluronic F127(A (R)) as stabilizer. The suitability of paclitaxel

  6. Quantum Dynamics of One-Dimensional Nanocrystalline Solids

    Institute of Scientific and Technical Information of China (English)

    丁建文; 颜晓红; 曹觉先; 王登龙

    2002-01-01

    A novel ballistic-nonballistic dynamic transition in one-dimensional nanocrystalline solids is found upon varyingthe strength of the composition modulation and the grain-boundary effect. This can contribute to the under-standing of the strange electronic transport properties of nanostructured systems.

  7. A new approach to grain boundary engineering for nanocrystalline materials.

    Science.gov (United States)

    Kobayashi, Shigeaki; Tsurekawa, Sadahiro; Watanabe, Tadao

    2016-01-01

    A new approach to grain boundary engineering (GBE) for high performance nanocrystalline materials, especially those produced by electrodeposition and sputtering, is discussed on the basis of some important findings from recently available results on GBE for nanocrystalline materials. In order to optimize their utility, the beneficial effects of grain boundary microstructures have been seriously considered according to the almost established approach to GBE. This approach has been increasingly recognized for the development of high performance nanocrystalline materials with an extremely high density of grain boundaries and triple junctions. The effectiveness of precisely controlled grain boundary microstructures (quantitatively characterized by the grain boundary character distribution (GBCD) and grain boundary connectivity associated with triple junctions) has been revealed for recent achievements in the enhancement of grain boundary strengthening, hardness, and the control of segregation-induced intergranular brittleness and intergranular fatigue fracture in electrodeposited nickel and nickel alloys with initial submicrometer-grained structure. A new approach to GBE based on fractal analysis of grain boundary connectivity is proposed to produce high performance nanocrystalline or submicrometer-grained materials with desirable mechanical properties such as enhanced fracture resistance. Finally, the potential power of GBE is demonstrated for high performance functional materials like gold thin films through precise control of electrical resistance based on the fractal analysis of the grain boundary microstructure.

  8. Nanocrystalline cellulose extracted from pine wood and corncob.

    Science.gov (United States)

    Ditzel, Fernanda I; Prestes, Eduardo; Carvalho, Benjamim M; Demiate, Ivo M; Pinheiro, Luís A

    2017-02-10

    The extraction of nanocrystalline cellulose from agro-residues is an interesting alternative to recover these materials. In the present study, nanocrystalline cellulose was extracted from pine wood and corncob. In addition, microcrystalline cellulose was used as a reference to compare results. Initially, the lignocellulosic residues were submitted to delignification pre-treatments. At the end of the process, the bleached fibre was submitted to acid hydrolysis. Additionally, microparticles were obtained from the spray-drying of the nanocrystalline cellulose suspensions. The nanocrystalline cellulose yield for the pine wood was 9.0-% of the value attained for the microcrystalline cellulose. For the corncob, the value was 23.5-%. Therefore, complementary studies are necessary to improve the yield. The spray-dried microparticles showed a crystallinity index of 67.8-% for the pine wood, 70.9-% for the corncob and 79.3-% for the microcrystalline cellulose. These microparticles have great potential for use in the production of polymer composites processed by extrusion.

  9. New route to the fabrication of nanocrystalline diamond films

    Science.gov (United States)

    Varshney, Deepak; Palomino, Javier; Gil, Jennifer; Resto, Oscar; Weiner, Brad R.; Morell, Gerardo

    2014-02-01

    Nanocrystalline diamond (NCD) thin films offer applications in various fields, but the existing synthetic approaches are cumbersome and destructive. A major breakthrough has been achieved by our group in the direction of a non-destructive, scalable, and economic process of NCD thin-film fabrication. Here, we report a cheap precursor for the growth of nanocrystalline diamond in the form of paraffin wax. We show that NCD thin films can be fabricated on a copper support by using simple, commonplace paraffin wax under reaction conditions of Hot Filament Chemical Vapor Deposition (HFCVD). Surprisingly, even the presence of any catalyst or seeding that has been conventionally used in the state-of-the-art is not required. The structure of the obtained films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectroscopy and electron energy-loss spectroscopy recorded at the carbon K-edge region confirm the presence of nanocrystalline diamond. The process is a significant step towards cost-effective and non-cumbersome fabrication of nanocrystalline diamond thin films for commercial production.

  10. Luminescence of nanocrystalline ZnSe:Mn2+

    NARCIS (Netherlands)

    Suyver, J.F.; Wuister, S.F.; Kelly, J.J.; Meijerink, A.

    2000-01-01

    The luminescence properties of nanocrystalline ZnSe:Mn^(2+) prepared via an inorganic chemical synthesis are described. Photoluminescence spectra show distinct ZnSe and Mn^(2+) related emissions, both of which are excited via the ZnSe host lattice. The Mn^(2+) emission wavelength and the

  11. Electrodeposited nanocrystalline bronze alloys as replacement for Ni

    NARCIS (Netherlands)

    Hovestad, A.; Tacken, R.A.; Mannetje, H.H.'t

    2008-01-01

    Nanocrystalline white-bronze, CuSn, electroplating was investigated as alternative to Ni plating as undercoat for noble metals in jewellery applications. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. Polarization

  12. Development of Bulk Nanocrystalline Cemented Tungsten Carbide for Industrial Applicaitons

    Energy Technology Data Exchange (ETDEWEB)

    Z. Zak Fang, H. Y. Sohn

    2009-03-10

    This report contains detailed information of the research program entitled "Development of Bulk Nanocrystalline Cemented Tungsten Carbide Materials for Industrial Applications". The report include the processes that were developed for producing nanosized WC/Co composite powders, and an ultrahigh pressure rapid hot consolidation process for sintering of nanosized powders. The mechanical properties of consolidated materials using the nanosized powders are also reported.

  13. Distinctive glial and neuronal interfacing on nanocrystalline diamond.

    Directory of Open Access Journals (Sweden)

    Amel Bendali

    Full Text Available Direct electrode/neuron interfacing is a key challenge to achieve high resolution of neuronal stimulation required for visual prostheses. Neuronal interfacing on biomaterials commonly requires the presence of glial cells and/or protein coating. Nanocrystalline diamond is a highly mechanically stable biomaterial with a remarkably large potential window for the electrical stimulation of tissues. Using adult retinal cell cultures from rats, we found that glial cells and retinal neurons grew equally well on glass and nanocrystalline diamond. The use of a protein coating increased cell survival, particularly for glial cells. However, bipolar neurons appeared to grow even in direct contact with bare diamond. We investigated whether the presence of glial cells contributed to this direct neuron/diamond interface, by using purified adult retinal ganglion cells to seed diamond and glass surfaces with and without protein coatings. Surprisingly, these fully differentiated spiking neurons survived better on nanocrystalline diamond without any protein coating. This greater survival was indicated by larger cell numbers and the presence of longer neurites. When a protein pattern was drawn on diamond, neurons did not grow preferentially on the coated area, by contrast to their behavior on a patterned glass. This study highlights the interesting biocompatibility properties of nanocrystalline diamond, allowing direct neuronal interfacing, whereas a protein coating was required for glial cell growth.

  14. Distinctive glial and neuronal interfacing on nanocrystalline diamond.

    Science.gov (United States)

    Bendali, Amel; Agnès, Charles; Meffert, Simone; Forster, Valérie; Bongrain, Alexandre; Arnault, Jean-Charles; Sahel, José-Alain; Offenhäusser, Andreas; Bergonzo, Philippe; Picaud, Serge

    2014-01-01

    Direct electrode/neuron interfacing is a key challenge to achieve high resolution of neuronal stimulation required for visual prostheses. Neuronal interfacing on biomaterials commonly requires the presence of glial cells and/or protein coating. Nanocrystalline diamond is a highly mechanically stable biomaterial with a remarkably large potential window for the electrical stimulation of tissues. Using adult retinal cell cultures from rats, we found that glial cells and retinal neurons grew equally well on glass and nanocrystalline diamond. The use of a protein coating increased cell survival, particularly for glial cells. However, bipolar neurons appeared to grow even in direct contact with bare diamond. We investigated whether the presence of glial cells contributed to this direct neuron/diamond interface, by using purified adult retinal ganglion cells to seed diamond and glass surfaces with and without protein coatings. Surprisingly, these fully differentiated spiking neurons survived better on nanocrystalline diamond without any protein coating. This greater survival was indicated by larger cell numbers and the presence of longer neurites. When a protein pattern was drawn on diamond, neurons did not grow preferentially on the coated area, by contrast to their behavior on a patterned glass. This study highlights the interesting biocompatibility properties of nanocrystalline diamond, allowing direct neuronal interfacing, whereas a protein coating was required for glial cell growth.

  15. Light emission, light detection and strain sensing with nanocrystalline graphene.

    Science.gov (United States)

    Riaz, Adnan; Pyatkov, Feliks; Alam, Asiful; Dehm, Simone; Felten, Alexandre; Chakravadhanula, Venkata S K; Flavel, Benjamin S; Kübel, Christian; Lemmer, Uli; Krupke, Ralph

    2015-08-14

    Graphene is of increasing interest for optoelectronic applications exploiting light detection, light emission and light modulation. Intrinsically, the light-matter interaction in graphene is of a broadband type. However, by integrating graphene into optical micro-cavities narrow-band light emitters and detectors have also been demonstrated. These devices benefit from the transparency, conductivity and processability of the atomically thin material. To this end, we explore in this work the feasibility of replacing graphene with nanocrystalline graphene, a material which can be grown on dielectric surfaces without catalyst by graphitization of polymeric films. We have studied the formation of nanocrystalline graphene on various substrates and under different graphitization conditions. The samples were characterized by resistance, optical transmission, Raman and x-ray photoelectron spectroscopy, atomic force microscopy and electron microscopy measurements. The conducting and transparent wafer-scale material with nanometer grain size was also patterned and integrated into devices for studying light-matter interaction. The measurements show that nanocrystalline graphene can be exploited as an incandescent emitter and bolometric detector similar to crystalline graphene. Moreover the material exhibits piezoresistive behavior which makes nanocrystalline graphene interesting for transparent strain sensors.

  16. Nanocrystalline cellulose with various contents of sulfate groups.

    Science.gov (United States)

    Voronova, M I; Surov, O V; Zakharov, A G

    2013-10-15

    Properties of films derived from aqueous nanocrystalline cellulose dispersions by water evaporation depend on concentration of sulfate groups. Namely type of thermodestruction and surface morphology change as a function of contents of sulfate groups. Surface roughness increases and water adsorption enhances with increasing sulfate groups content particularly at high relative pressure.

  17. Toward a quantitative understanding of mechanical behavior of nanocrystalline metals

    NARCIS (Netherlands)

    Dao, M.; Lu, L.; Asaro, R. J.; De Hosson, J. T. M.; Ma, E.

    Focusing on nanocrystalline (nc) pure face-centered cubic metals, where systematic experimental data are available, this paper presents a brief overview of the recent progress made in improving mechanical properties of nc materials, and in quantitatively and mechanistically understanding the

  18. New route to the fabrication of nanocrystalline diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Varshney, Deepak, E-mail: deepvar20@gmail.com; Morell, Gerardo [Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00931, Puerto Rico (United States); Department of Physics, University of Puerto Rico, San Juan, PO Box 70377, Puerto Rico 00936, Puerto Rico (United States); Palomino, Javier; Resto, Oscar [Department of Physics, University of Puerto Rico, San Juan, PO Box 70377, Puerto Rico 00936, Puerto Rico (United States); Gil, Jennifer [Department of Chemistry, University of Puerto Rico, San Juan, Puerto Rico 00936, Puerto Rico (United States); Weiner, Brad R. [Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00931, Puerto Rico (United States); Department of Chemistry, University of Puerto Rico, San Juan, Puerto Rico 00936, Puerto Rico (United States)

    2014-02-07

    Nanocrystalline diamond (NCD) thin films offer applications in various fields, but the existing synthetic approaches are cumbersome and destructive. A major breakthrough has been achieved by our group in the direction of a non-destructive, scalable, and economic process of NCD thin-film fabrication. Here, we report a cheap precursor for the growth of nanocrystalline diamond in the form of paraffin wax. We show that NCD thin films can be fabricated on a copper support by using simple, commonplace paraffin wax under reaction conditions of Hot Filament Chemical Vapor Deposition (HFCVD). Surprisingly, even the presence of any catalyst or seeding that has been conventionally used in the state-of-the-art is not required. The structure of the obtained films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectroscopy and electron energy-loss spectroscopy recorded at the carbon K-edge region confirm the presence of nanocrystalline diamond. The process is a significant step towards cost-effective and non-cumbersome fabrication of nanocrystalline diamond thin films for commercial production.

  19. Distinctive Glial and Neuronal Interfacing on Nanocrystalline Diamond

    Science.gov (United States)

    Bendali, Amel; Agnès, Charles; Meffert, Simone; Forster, Valérie; Bongrain, Alexandre; Arnault, Jean-Charles; Sahel, José-Alain; Offenhäusser, Andreas; Bergonzo, Philippe; Picaud, Serge

    2014-01-01

    Direct electrode/neuron interfacing is a key challenge to achieve high resolution of neuronal stimulation required for visual prostheses. Neuronal interfacing on biomaterials commonly requires the presence of glial cells and/or protein coating. Nanocrystalline diamond is a highly mechanically stable biomaterial with a remarkably large potential window for the electrical stimulation of tissues. Using adult retinal cell cultures from rats, we found that glial cells and retinal neurons grew equally well on glass and nanocrystalline diamond. The use of a protein coating increased cell survival, particularly for glial cells. However, bipolar neurons appeared to grow even in direct contact with bare diamond. We investigated whether the presence of glial cells contributed to this direct neuron/diamond interface, by using purified adult retinal ganglion cells to seed diamond and glass surfaces with and without protein coatings. Surprisingly, these fully differentiated spiking neurons survived better on nanocrystalline diamond without any protein coating. This greater survival was indicated by larger cell numbers and the presence of longer neurites. When a protein pattern was drawn on diamond, neurons did not grow preferentially on the coated area, by contrast to their behavior on a patterned glass. This study highlights the interesting biocompatibility properties of nanocrystalline diamond, allowing direct neuronal interfacing, whereas a protein coating was required for glial cell growth. PMID:24664111

  20. Synthesis Method and Absorption Application of Nanocrystalline Alloy Flakes

    Institute of Scientific and Technical Information of China (English)

    Pei-Heng Zhou; Long-Jiang Deng

    2007-01-01

    The soft magnetic FeSiB nanocrystalline/amorphous flakes were fabricated by ball milling from the elemental powders and annealing the amorphous precursor, respectively. The microstructure, magnetic and microwave properties were evaluated by different synthesis methods. By computation, ballmilled Fe78Si13B9 flakes demonstrated potential application in absorption.

  1. Light scattering characteristicof TiO2 nanocrystalline porous films

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    TiO2 nanocrystalline porous films consisting of binary particles mixture (mean diameters of 12 and 100 nm) are capable of increasing the light absorption due to the possession of large specific surface area and light scattering property. The simultaneous reduction of the film thickness leads to a decrease of the recombination loss during electron transport and an increase of the photocurrent efficiency.

  2. Quantum dynamics of one-dimensional nanocrystalline solids

    CERN Document Server

    Ding Jian Wen; Cao Jue Xian; Wang Deng Long

    2002-01-01

    A novel ballistic-non-ballistic dynamic transition in one-dimensional nanocrystalline solids is found upon varying the strength of the composition modulation and the grain-boundary effect. This can contribute to the understanding of the strange electronic transport properties of nano-structured systems

  3. Oxygen reduction on nanocrystalline ruthenia-local structure effects

    DEFF Research Database (Denmark)

    Abbott, Daniel F.; Mukerjee, Sanjeev; Petrykin, Valery;

    2015-01-01

    Nanocrystalline ruthenium dioxide and doped ruthenia of the composition Ru1-xMxO2 (M = Co, Ni, Zn) with 0 ≤ x ≤ 0.2 were prepared by the spray-freezing freeze-drying technique. The oxygen reduction activity and selectivity of the prepared materials were evaluated in alkaline media using the RRDE...

  4. Terbium-based extreme ultraviolet multilayers.

    Science.gov (United States)

    Windt, David L; Seely, John F; Kjornrattanawanich, Benjawan; Uspenskii, Yu A

    2005-12-01

    We have fabricated periodic multilayers that comprise either Si/Tb or SiC/Tb bilayers, designed to operate as narrowband reflective coatings near 60 nm wavelength in the extreme ultraviolet (EUV). We find peak reflectance values in excess of 20% near normal incidence. The spectral bandpass of the best Si/Tb multilayer was measured to be 6.5 nm full width at half-maximum (FWHM), while SiC/Tb multilayers have a more broad response, of order 9.4 nm FWHM. Transmission electron microscopy analysis of Si/Tb multilayers reveals polycrystalline Tb layers, amorphous Si layers, and relatively large asymmetric amorphous interlayers. Thermal annealing experiments indicate excellent stability to 100 degrees C (1 h) for Si/Tb. These new multilayer coatings have the potential for use in normal incidence instrumentation in a region of the EUV where efficient narrowband multilayers have not been available until now. In particular, reflective Si/Tb multilayers can be used for solar physics applications where the coatings can be tuned to important emission lines such as O V near 63.0 nm and Mg X near 61.0 nm.

  5. Determination of elastic and thermal properties of a thin nanocrystalline diamond coating using all-optical methods

    Energy Technology Data Exchange (ETDEWEB)

    Sermeus, J.; Verstraeten, B.; Salenbien, R. [KU Leuven-University of Leuven, Soft Matter and Biophysics, Celestijnenlaan 200D, B-3001 Heverlee (Belgium); Pobedinskas, P.; Haenen, K. [Instituut voor Materiaalonderzoek (IMO), Hasselt University, Wetenschapspark 1, 3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, 3590 Diepenbeek (Belgium); Glorieux, C., E-mail: christ.glorieux@fys.kuleuven.be [KU Leuven-University of Leuven, Soft Matter and Biophysics, Celestijnenlaan 200D, B-3001 Heverlee (Belgium)

    2015-09-01

    Results are presented on the thermal and elastic properties of a thin, 1.5 μm, nanocrystalline diamond coating (NCD), deposited on a silicon substrate by microwave plasma enhanced chemical vapor deposition. A combination of two all-optical measurement techniques, impulsive stimulated thermal scattering and grating induced laser beam deflection, was employed to launch and detect surface acoustic waves (SAWs). The relation between the dispersive propagation velocity of SAWs to the coating-substrate geometry is exploited to determine the elastic properties of the NCD coating. The elastic properties are found to be consistent with literature values. The thermal properties of the coating were determined by monitoring the thermal diffusion induced washing away of the laser induced transient surface temperature grating. The transient thermal grating signals were fitted by the low-frequency limit of a thermoelastic model for a multilayer configuration. Similar to the dispersion of the surface acoustic wave velocity, the characteristic time of the thermal diffusion driven grating decay evolves from a coating-dominated value at short grating spacings towards a substrate-dominated value at grating spacings well exceeding the coating thickness. The grating spacing dependence of the corresponding effective thermal diffusivity was experimentally determined and fitted, leading to a value for the thermal diffusivity of the NCD coating α{sub NCD} = 8.4{sub −0.1}{sup +2.7} mm{sup 2}·s{sup −1}, which is an order of magnitude lower than that of the silicon substrate. The low value of the thermal diffusivity is interpreted with a simple touching model. - Highlights: • We investigate a thin nano-crystalline diamond coating. • We used two all optical surface acoustic wave based methods. • We found a young's modulus and density that is in line with literature. • The thermal diffusivity of the NCD coating was 2 orders of magnitude lower than the one of bulk diamond.

  6. Hydrogen plasma treatment of very thin p-type nanocrystalline Si films grown by RF-PECVD in the presence of B(CH33

    Directory of Open Access Journals (Sweden)

    Sergej Alexandrovich Filonovich, Hugo Águas, Tito Busani, António Vicente, Andreia Araújo, Diana Gaspar, Marcia Vilarigues, Joaquim Leitão, Elvira Fortunato and Rodrigo Martins

    2012-01-01

    Full Text Available We have characterized the structure and electrical properties of p-type nanocrystalline silicon films prepared by radio-frequency plasma-enhanced chemical vapor deposition and explored optimization methods of such layers for potential applications in thin-film solar cells. Particular attention was paid to the characterization of very thin (~20 nm films. The cross-sectional morphology of the layers was studied by fitting the ellipsometry spectra using a multilayer model. The results suggest that the crystallization process in a high-pressure growth regime is mostly realized through a subsurface mechanism in the absence of the incubation layer at the substrate-film interface. Hydrogen plasma treatment of a 22-nm-thick film improved its electrical properties (conductivity increased more than ten times owing to hydrogen insertion and Si structure rearrangements throughout the entire thickness of the film.

  7. Thermal stability of nanoscale metallic multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, A.S., E-mail: sofia.ramos@dem.uc.pt [CEMUC, Departamento de Engenharia Mecânica, Universidade de Coimbra, 3030-788 Coimbra (Portugal); Cavaleiro, A.J.; Vieira, M.T. [CEMUC, Departamento de Engenharia Mecânica, Universidade de Coimbra, 3030-788 Coimbra (Portugal); Morgiel, J. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Reymonta 25, 30-059 Cracow (Poland); Safran, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, H-1121 Budapest (Hungary)

    2014-11-28

    Metallic nanolayered thin films/foils, in particular Ni/Al multilayers, have been used to promote joining. The objective of this work is to evaluate the thermal stability of nanoscale metallic multilayers with potential for joining applications. Multilayers thin films with low (Ti/Al and Ni/Ti), medium (Ni/Al) and high (Pd/Al) enthalpies of exothermic reaction were prepared by dual cathode magnetron sputtering. Their thermal stability was studied by: i) differential scanning calorimetry combined with X-ray diffraction (XRD), ii) in-situ XRD using cobalt radiation, and iii) in-situ transmission electron microscopy. It was possible to detect traces of intermetallic or amorphous phases in the as-deposited short period (bilayer thickness) multilayers, except for the Ti/Al films where no reaction products that might be formed during deposition were identified. For short periods (below 20 nm) the equilibrium phases are directly achieved upon annealing, whereas for higher periods intermediate trialuminide phases are present for Ti/Al and Ni/Al multilayers. The formation of B2-NiTi from Ni/Ti multilayers occurs without the formation of intermediate phases. On the contrary, for the Pd–Al system the formation of intermediate phases was never avoided. The viability of nanoscale multilayers as “filler” materials for joining macro or microparts/devices was demonstrated. - Highlights: • Me1 and Me2 (Me—metal) alternated nanolayers deposited by magnetron sputtering • Reactive Me1/Me2 multilayer thin films with nanometric modulation period • By heat treatment the films always evolve to the equilibrium intermetallic phase. • For some Me1–Me2 systems and periods, the formation of intermediate phases occurs. • Me1/Me2 multilayer thin films can be used as filler materials to enhance joining.

  8. Development of a dielectric ceramic based on diatomite-titania. Part one: powder preparation and sintering study

    Directory of Open Access Journals (Sweden)

    Tavares Elcio Correia de Souza

    1997-01-01

    Full Text Available This work presents powder preparation and sintering experiments of a mixture diatomite-titania. X-ray diffraction, DTA, TGA as well as chemical and microstructural analyses were made. The sintering process was investigated as a function of sintering temperature and time, mass variation, linear shrinkage and activation energy. The results show that sintering of diatomite-titania could be described by a viscous flow mechanism.

  9. Visible-Light Degradation of Dyes and Phenols over Mesoporous Titania Prepared by Using Anthocyanin from Red Radish as Template

    OpenAIRE

    Zhiying Yan; Wenjuan Gong; Yongjuan Chen; Deliang Duan,; Junjie Li; Wei Wang; Jiaqiang Wang

    2014-01-01

    Heterogeneous photocatalysis is able to operate effectively to eliminate organic compounds from wastewater in the presence of semiconductor photocatalyst and a light source. Although photosensitization of titania by organic dyes is one of the conventional ways for visible-light utilization of titania, previous studies have not yet addressed the use of natural food coloring agents as templates in the synthesis of mesostructured materials, let alone the simultaneous achievement of highly crysta...

  10. Magnetic quantization in multilayer graphenes

    CERN Document Server

    Lin, Chiun-Yan; Ou, Yih-Jon; Chiu, Yu-Huang; Lin, Ming-Fa

    2015-01-01

    Essential properties of multilayer graphenes are diversified by the number of layers and the stacking configurations. For an $N$-layer system, Landau levels are divided into $N$ groups, with each identified by a dominant sublattice associated with the stacking configuration. We focus on the main characteristics of Landau levels, including the degeneracy, wave functions, quantum numbers, onset energies, field-dependent energy spectra, semiconductor-metal transitions, and crossing patterns, which are reflected in the magneto-optical spectroscopy, scanning tunneling spectroscopy, and quantum transport experiments. The Landau levels in AA-stacked graphene are responsible for multiple Dirac cones, while in AB-stacked graphene the Dirac properties depend on the number of graphene layers, and in ABC-stacked graphene the low-lying levels are related to surface states. The Landau-level mixing leads to anticrossings patterns in energy spectra, which are seen for intergroup Landau levels in AB-stacked graphene, while in...

  11. The physics of multilayer networks

    CERN Document Server

    De Domenico, Manlio; Porter, Mason A; Arenas, Alex

    2016-01-01

    The study of networks plays a crucial role in investigating the structure, dynamics, and function of a wide variety of complex systems in myriad disciplines. Despite the success of traditional network analysis, standard networks provide a limited representation of these systems, which often includes different types of relationships (i.e., "multiplexity") among their constituent components and/or multiple interacting subsystems. Such structural complexity has a significant effect on both dynamics and function. Throwing away or aggregating available structural information can generate misleading results and provide a major obstacle towards attempts to understand the system under analysis. The recent "multilayer' approach for modeling networked systems explicitly allows the incorporation of multiplexity and other features of realistic networked systems. On one hand, it allows one to couple different structural relationships by encoding them in a convenient mathematical object. On the other hand, it also allows o...

  12. Centrality in Interconnected Multilayer Networks

    CERN Document Server

    De Domenico, Manlio; Omodei, Elisa; Gómez, Sergio; Arenas, Alex

    2013-01-01

    Real-world complex systems exhibit multiple levels of relationships. In many cases, they require to be modeled by interconnected multilayer networks, characterizing interactions on several levels simultaneously. It is of crucial importance in many fields, from economics to biology, from urban planning to social sciences, to identify the most (or the less) influent nodes in a network. However, defining the centrality of actors in an interconnected structure is not trivial. In this paper, we capitalize on the tensorial formalism, recently proposed to characterize and investigate this kind of complex topologies, to show how several centrality measures -- well-known in the case of standard ("monoplex") networks -- can be extended naturally to the realm of interconnected multiplexes. We consider diagnostics widely used in different fields, e.g., computer science, biology, communication and social sciences, to cite only some of them. We show, both theoretically and numerically, that using the weighted monoplex obta...

  13. Hot Superplastic Powder Forging for Transparent nanocrystalline Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, W. Roger

    2006-05-22

    The program explored a completely new, economical method of manufacturing nanocrystalline ceramics, Hot Superplastic Powder Forging (HSPF). The goal of the work was the development of nanocrystalline/low porosity optically transparent zirconia/alumina. The high optical transparency should result from lack of grain boundary scattering since grains will be smaller than one tenth the wavelength of light and from elimination of porosity. An important technological potential for this process is manufacturing of envelopes for high-pressure sodium vapor lamps. The technique for fabricating monolithic nanocrystalline material does not begin with powder whose particle diameter is <100 nm as is commonly done. Instead it begins with powder whose particle diameter is on the order of 10-100 microns but contains nanocrystalline crystallites <<100 nm. Spherical particles are quenched from a melt and heat treated to achieve the desired microstructure. Under a moderate pressure within a die or a mold at temperatures of 1100C to 1300C densification is by plastic flow of superplastic particles. A nanocrystalline microstructure results, though some features are greater than 100nm. It was found, for instance, that in the fully dense Al2O3-ZrO2 eutectic specimens that a bicontinuous microstructure exists containing <100 nm ZrO2 particles in a matrix of Al2O3 grains extending over 1-2 microns. Crystallization, growth, phase development and creep during hot pressing and forging were studied for several compositions and so provided some details on development of polycrystalline microstructure from heating quenched ceramics.

  14. Activity of nanosized titania synthesized from thermal decomposition of titanium (IV n-butoxide for the photocatalytic degradation of diuron

    Directory of Open Access Journals (Sweden)

    Jitlada Klongdee, Wansiri Petchkroh, Kosin Phuempoonsathaporn, Piyasan Praserthdam, Alisa S. Vangnai and Varong Pavarajarn

    2005-01-01

    Full Text Available Nanoparticles of anatase titania were synthesized by the thermal decomposition of titanium (IV n-butoxide in 1,4-butanediol. The powder obtained was characterized by various characterization techniques, such as XRD, BET, SEM and TEM, to confirm that it was a collection of single crystal anatase with particle size smaller than 15 nm. The synthesized titania was employed as catalyst for the photodegradation of diuron, a herbicide belonging to the phenylurea family, which has been considered as a biologically active pollutant in soil and water. Although diuron is chemically stable, degradation of diuron by photocatalyzed oxidation was found possible. The conversions achieved by titania prepared were in the range of 70–80% within 6 h of reaction, using standard UV lamps, while over 99% conversion was achieved under solar irradiation. The photocatalytic activity was compared with that of the Japanese Reference Catalyst (JRC-TIO-1 titania from the Catalysis Society of Japan. The synthesized titania exhibited higher rate and efficiency in diuron degradation than reference catalyst. The results from the investigations by controlling various reaction parameters, such as oxygen dissolved in the solution, diuron concentration, as well as light source, suggested that the enhanced photocatalytic activity was the result from higher crystallinity of the synthesized titania.

  15. Influence of chitosan–PEG binary template on the crystallite characteristics of sol–gel synthesized mesoporous nano-titania photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Preethi, T.; Abarna, B.; Rajarajeswari, G.R., E-mail: rajiaravind@gmail.com

    2014-10-30

    Highlights: • Binary templated (PEG and chitosan) mesoporous nano titania was prepared by sol–gel method. • PEG:chitosan in the ratio of 1:3 (P1-C3 titania) offered the best template effect. • P1-C3 titania had superior activity in degrading 4-chlorophenol under UV irradiation. • PEG acted as a physical template for mesopore formation. • Chitosan played a major role in defining the crystallite dimensions. - Abstract: Nano-titania is by far, the most studied material for its photocatalytic application in air and water pollution abatement. In this study, we have demonstrated the advantage offered by using a binary template of PEG and chitosan for the sol–gel synthesis of titania. Nano-titania samples were prepared using PEG, chitosan and the binary combination of these two as templates. XRD showed that all synthesized samples preserved the anatase structure. Titania sample prepared on 1% PEG and 3% chitosan as template (P1-C3 titania) possessed spherical shaped particles with an average particle size of 12.3 nm, a surface area of 82.9 m{sup 2}/g and uniform dispersion. DRS UV–Vis spectra indicated that, P1-C3 titania showed blue shift in its absorption profile due to decrease in particle size. Consistent with the characteristics, the P1-C3 titania exhibited the highest photocatalytic activity for the degradation of 4-chlorophenol under UV irradiation, in comparison with all the synthesized photocatalytic systems and Degussa-P25. The chitosan bio template is believed to offer controlled growth of titania through Lewis base type interaction with Ti metallic centers in TiO{sub 2}. Such controlled growth route will be significant in synthesizing custom-made titania for its advanced applications in catalytic processes.

  16. Correlation between Light Emissions from Amorphous-Si:H/SiO2 and nc-Si/SiO2 Multilayers

    Institute of Scientific and Technical Information of China (English)

    MA Zhong-Yuan; HUANG Xin-Fan; CHEN Kun-Ji; FENG Duan; HAN Pei-Gao; LI Wei; CHEN De-Yuan; WEI De-Yuan; QIAN Bo; LI Wei; XU Jun; XU Ling

    2007-01-01

    We investigate the properties of light emission from amorphous-Si:H/SiO2 and nc-Si/SiO2 multilayers (MLs). The size dependence of light emission is well exhibited when the a-Si:H sublayer thickness is thinner than 4nm and the interface states are well passivated by hydrogen. For the nc-Si/SiO2 MLs, the oxygen modified interface states and nanocrystalline silicon play a predominant role in the properties of light emission. It is found that the light emission from nc-Si/SiO2 is in agreement with the model of interface state combining with quantum confinement when the size of nc-Si is smaller than 4 nm. The role of hydrogen and oxygen is discussed in detail.

  17. Step-by-Step Laser Crystallization of Amorphous Si:H/SiNx:H Multilayer for Active Layer in Microcavities

    Institute of Scientific and Technical Information of China (English)

    QIAN Bo; CHEN San; CEN Zhan-Hong; CHEN Kun-Ji; LIU Yan-Song; XU Jun; MA Zhong-Yuan; LI Wei; HUANG Xin-Fan

    2006-01-01

    @@ We report the crystallization and photoluminescence (PL) properties of amorphous Si:H/SiNx :H multilayer (ML)films treated by step-by-step laser annealing. The results of Raman measurements show that the nanocrystalline Si (nc-Si) grains are formed in the a-Si:H layers under the constrained growth mechanism. The blue shift of PL peak with grain size is observed and can be attributed to the quantum confinement effect. For comparison, we also report the crystallization and PL of a-Si:H/SiNx :H ML samples by normal one-step treatment. This method of step-by-step laser treatment will be a candidate to make nc-Si quantum dots in amorphous Si:H/SiNx :H ML as an active layer in microcavities.

  18. Biomolecule-mediated synthesis of nanocrystalline semiconductors

    Science.gov (United States)

    Bae, Weon

    CdS and ZnS nanocrystalline semiconductors (NCs) were prepared by titrating inorganic sulfide into preformed Cd(II)- or Zn(II)-complexes of phytochelatins, glutathione or cysteine. This strategy resulted in the formation NCs capped by the chosen biomolecule. The range of sizes and their distributions depended primarily on the quantity of sulfide titrated and the biomolecule chosen for the initial metallo-complex. The processes of NC formation were studied by absorption and fluorescence spectrophotometry. The size distribution was analyzed by gel permeation chromatography. Ethanol precipitation of NCs under aqueous conditions was used to isolate nanoparticles within a very narrow size-range. Reduction of selected dyes was also studied on the surfaces of NCs. Glutathione-capped CdS nanoparticles exhibited significant size heterogeneity even at a single sulfide titration. In contrast, phytochelatins showed much less dispersion in size at a given sulfide titration. Phytochelatins could replace glutathione without changing the size of glutathione-capped CdS nanoparticles. Cysteine appeared to be intermediate between glutathione and phytochelatins in the formation of CdS nanoparticles. The calculated radii, using an effective mass approximation method, were 10.8-17.3, 10.6-11.8, and 13.5-15.5A for glutathione-, phytochelatin-, and cysteine-capped CdS nanoparticles, respectively. Cysteine-capped ZnS showed narrower size distribution than glutathione-capped ZnS. However, elevated temperatures were necessary to accomplish optimal yields of cysteine-capped ZnS NCs. An additional control over the size distribution of NCs was achieved by size-selective precipitation with ethanol. These procedures led to the isolation of nanoparticles that were more uniform in size and chemical compositions as determined by spectroscopic and chemical analyses of size-fractionated samples. Precipitation also allowed preparation of large quantities of powdered nanoparticles that could be

  19. NATO Advanced Research Workshop on Properties and Applications of Nanocrystalline Alloys from Amorphous Precursors

    CERN Document Server

    Idzikowski, Bogdan; Miglierini, Marcel

    2005-01-01

    Metallic (magnetic and non-magnetic) nanocrystalline materials have been known for over ten years but only recent developments in the research into those complex alloys and their metastable amorphous precursors have created a need to summarize the most important accomplishments in the field. This book is a collection of articles on various aspects of metallic nanocrystalline materials, and an attempt to address this above need. The main focus of the papers is put on the new issues that emerge in the studies of nanocrystalline materials, and, in particular, on (i) new compositions of the alloys, (ii) properties of conventional nanocrystalline materials, (iii) modeling and simulations, (iv) preparation methods, (v) experimental techniques of measurements, and (vi) different modern applications. Interesting phenomena of the physics of nanocrystalline materials are a consequence of the effects induced by the nanocrystalline structure. They include interface physics, the influence of the grain boundaries, the aver...

  20. Soft X-ray multilayers and filters

    CERN Document Server

    Wang Zhan Shan; Tang Wei Xing; Qin Shuji; Zhou Bing; Chen Ling Ya

    2002-01-01

    The periodic and non-periodic multilayers were designed by using a random number to change each layer and a suitable merit function. Ion beam sputtering and magnetron sputtering were used to fabricate various multilayers and beam splitters in soft X-ray range. The characterization of multilayers by small angle X-ray diffraction, Auger electron spectroscopy, Rutherford back scattering spectroscopy and reflectivity illustrated the multilayers had good structures and smooth interlayers. The reflectivity and transmission of a beam splitter is about 5%. The fabrication and transmission properties of Ag, Zr were studied. The Rutherford back scattering spectroscopy and auger electron spectroscopy were used to investigate the contents and distributions of impurities and influence on qualities of filters. The attenuation coefficients were corrected by the data obtained by measurements