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Nanofibers of titania and composite nanofibers of titania and multiwall carbon nanotubes were synthesized by electrospinning using a sol-gel process combined with activated carbon nanotubes. The relationships of treatment temperature, carbon nanotube content on the crystal phase, fiber morphology, and electric properties are reported. It is found that the rutile phase becomes more prominent at low heat treatment temperatures with an increase of carbon content in nanofibers, be it for higher amount of carbon due to reducing atmosphere or due to an increase in MWCNT. Atmospheric control and lower heat treatment temperatures enable crystalline nanocomposite fibers of anatase where the level of rutile is below the detection limit of XRD or Raman spectroscopy. This work provides a new path to fabricate electrospun TiO2/MWCNT nanocomposite nanofibers with limited C-induced rutile phase.

TiO 2 is one of the most exciting anode candidates for safe application in lithium ion batteries. However, its low intrinsic electronic conductivity limits application. In this paper, a simple sol–gel based route is presented to produce nanosize TiO 2 fibers with 119 ± 27 nm diameters via electrospinning. Subsequent calcination in various atmospheres was applied to achieve anatase and anatase-rutile mixed phase crystallites with and without carbon coating. The crystallite size was 5 nm for argon calcined fibers and 13–20 nm for air calcined fibers. Argon calcined TiO 2 nanofibers exhibited electronic conductivity orders of magnitude higher than those of air-calcined samples. Lithium diffusivity was increased by one time and specific capacity by 26.9% due to the enhanced conductivity. It also had a different intercalation mechanism of lithium. Hydrogen post heat-treatment was found to benefit electronic conductivity (by 3–4.5 times), lithium diffusivity (1.5–2 times) and consequently the high rate performance of the TiO 2 nanofibers (over 80%). The inner mechanism and structure-property relations among these parameters were also discussed.

A sol–gel based route was used to produce TiO 2 based nanocomposites. Sols were electrospun into continuous nanofibers and calcined to get rutile phase. Fibers with diameter around 100 nm and crystallites size between 10 and 50 nm were obtained. The morphological impact and crystallites size dependence of the electrochemical performance for as-synthesized materials are reported. Enhancements using inert calcination atmosphere and incorporation of multi-wall carbon nanotubes (MWCNT) into the system are also presented.

a b s t r a c t Nanosize LiNixFe1−xPO4 solid solution and LiNixFe1−xPO4/C nanocomposites were prepared via a solid state reaction method under argon atmosphere. A single phase olivine-type structure with Pnma space group was determined by X-ray diffraction. Crystallite sizes were found to be around 50 nm. A linear relationship was observed between lattice parameters and chemical composition which follows Veg- ard's law. Synthesized materials displayed electronic conductivity similar to previous reported values of LiFePO4. Carbon coating further increased the overall conductivity of nanocomposites to the order of 10 −3 S/cm. Chemical delithiation via NO2BF4 oxidant extracted more than 95% of lithium from the solid solution material accompanied by a decrease in lattice parameters.

Hybrid nanofibers of polyaniline/polyoxometalate are synthesized via a facile interfacial polymerization method for the first time, and evaluated as a cathode material for lithium ion batteries. The hybrid nanofibers with 100 nm diameter consisted of phosphomolybdic acid polyanion, [PMo12O40]3–, and polyaniline matrix. Their 1D geometry improves the utilization of electrode materials and accommodates the volume change during cycling, which enables the significant improvement in lithium storage capacity and capacity retentions. The phosphomolybdic acid polyanions not only exhibit a large theoretical capacity of about 270 mAh g–1, but also reduce the charge transfer resistance of electrode leading to the enhanced reversible capacity and rate capability. The polyaniline/polyoxometalate nanofibers delivered a remarkably improved electrochemical performance in terms of lithium storage capacity (183.4 mAh g–1 at 0.1C rate), cycling stability (80.7% capacity retention after 50 cycles), and rate capability (94.2 ...

Tin oxide (SnO2) is a promising candidate as an anode for lithium ion batteries because of its high theoretical capacity. However, poor capacity retention caused by large volume changes during cycling, large initial irreversible capacity, and low rate capability frustrate its practical application. We have developed a ternary nanocomposite based on tin indium oxide (SnO2–In2O3) and graphene nanosheet (GNS) synthesized via a facile solvothermal method. The incorporation of In2O3 into SnO2 can improve the electrochemical property of SnO2 and reduce the charge transfer resistance of electrode leading to the enhanced reversible capacity and rate capability. The graphene nanosheet in the composite electrode can accommodate high volume expansion/contraction during cycling resulting in excellent capacity retention. As an anode for lithium ion batteries, the SnO2–In2O3/GNS nanocomposite exhibits a remarkably improved electrochemical performance in terms of lithium storage capacity (962 mAh g−1 at 60 mA g−1 rate), initial coulombic efficiency (57.2%), cycling stability (60.8% capacity retention after 50 cycles), and rate capability (393.25 mAh g−1 at 600 mA g−1 rate after 25 cycles) compared to SnO2/GNS and pure SnO2–In2O3 electrode.

Crystal-growth-related microstructures and the length-to-diameter ratio of a single-crystal-type α-Al 2 O 3 nanofiber were examined using HR-TEM techniques. The fibers exhibited diameters ranging from 50 to 100 nm and lengths of several tens of micrometers. During thermal treatments, the alumina fiber went through phase transformations similar to boehmite. Therefore, the phase evolution, especially the final θ- to α-Al 2 O 3 stage of the phase transformation, may be the determining factor in the microstructural evolution of the nanofibers. HR-TEM techniques were utilized to demonstrate that the single crystals were formed by the coalescence of well-elongated α-Al 2 O 3 colonies. The fibers grew in the [1 1 0] or [1 1 2] direction instead of [0 0 1]. A thermodynamic analysis revealed that if the α-Al 2 O 3 nanofiber that transformed from θ-Al 2 O 3 behaved in a stable manner, there could be a size ratio limit for the length and diameter of each α-Al 2 O 3 colony. The smallest potential diameter was calculated to be around 17 nm.

Long-length nanofibers are able to form porous networks with high surface-area-to-volume ratios, and decrease diffusion lengths. While there are numerous techniques to create nanostructures, electrospinning is the only technique that allows fabrication of nanofibers at long-length scales. These uniquely shaped fibers are applied to several energy-related devices. This review is an in-depth summary of the uses of electrospun fibers in dye-sensitized solar cells (DSSCs), batteries, capacitors, fuel cells, and hydrogen storage devices. Developments in electrospinning technologies to create novel fiber morphologies are also discussed.

Nanocrystalline octahedra of cobalt ferrite CoFe 2 O 4 powders were synthesized using the organic acid precursor route. The effect of the calcination temperature, Fe 3+ /Co 2+ molar ratio, calcination time and type of organic acid (oxalic, benzoic and tartaric acids) on the formation, crystallite size, microstructure and magnetic properties was studied systematically. The Fe 3+ /Co 2+ molar ratio was varied from 2 to 1.739 while the annealing temperature was controlled from 400 to 1000 °C for various periods from 0.5 to 2 h. The resulting powders were investigated using X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). XRD results indicate that a well crystallized, single spinel cobalt ferrite phase was formed for the precursors annealed at 600–800 °C for 2 h, using oxalic and tartaric acids as precursors for Fe 3+ /Co 2+ molar ratio 1.818. The crystallite size of as-formed powders was in the range of 38.0–92.6 nm at different operating conditions. The calcination temperature and Fe 3+ /Co 2+ molar ratio have a significant effect on the microstructure of the produced cobalt ferrite. The microstructure of the produced powders was found to be octahedra-shaped. The crystalline, pure cobalt ferrite powders with magnetic properties having a maximum saturation magnetization (76.1 emu/g) was achieved for the single phase at Fe 3+ /Co 2+ molar ratio 1.818 and annealing temperature of 600 °C for 2 h using tartaric acid precursor.

Changes in the surface chemistry of LiFePO4 cathodes in an aqueous medium for lithium ion battery are investigated based on a quantitative evaluation of surface functional groups of LiFePO4 as a function of pH. It is found that, while the dissolution of Li ions from LiFePO4 increases the number of acidic surface groups, the dissolution of Fe ions reduces the number of basic surface groups. The pKa values for various processing conditions are calculated. Interestingly, none of the investigated processing conditions changes the characteristic acid moieties on the particles (pKa ∼ 2.8). However, the processing condition strongly impacts the chemistry of the basic surface groups showing three distinct basic surface groups with pKb values of 0.1, 0.9, and 1.5, respectively. Correlation is made between dissolution behavior, surface groups, dispersion properties, and electrochemical properties. It is found that Li-and Fe-ion depleted LiFePO4 powder increases the viscosity in N-methylpyrrolidone pastes 5-fold and...

Nanofiber filtration is drawing great interest nowadays because of its large surface collection area as well as low air resistance. In this study, electrospun nanofiber mats of different thicknesses were evaluated for their filter quality factors. Shorter-term electrospun fiber mats exhibited a better quality factor than those longer-term electrospun ones. Multiple thin layers of nanofiber mats to improve the filter quality of the nanofiber filters were then evaluated. Filtration test results showed that the filter made up of multiple thin layers of nanofiber mats had a filter quality factor much higher than the single thick layer nanofiber mat. Better thickness uniformity in the multi-layer structure due to stacking compensation and smaller fiber diameters in nanofibers of short-term deposition time are two possible reasons for the improvement of the filter quality.

The literature and advances in photocatalysis based on the combination of titania (TiO2) and carbon nanotubes is presented. The semiconductor basis for photocatalysis is introduced for anatase and rutile. Furthermore, the proposed mechanisms of catalytic enhancement resulting from the pairing of the titania semiconductor with either metallic, semiconducting, or defect-rich carbon nanotubes (CNT) is discussed. Differences are apparent for the mixtures and chemically bonded CNT–TiO2 composites. The article then highlights the recent advances in the synthesis techniques for these composites and their photocatalytic reactions with organic, inorganic, and biological agents. Finally, various applications and challenges for these composite materials are reported.

Shortened single-wall carbon nanotubes (sSWCNTs) were self-aligned vertically on poly(diallyl dimethyl ammonium) chloride (PDAC) self-assembled surfaces (silicon wafer and ITO glass). The self-aligned sSWCNT layer density was measured by atomic force microscopy (AFM) in dependence of reaction time, pH and salt concentration. It was found that the density of self-aligned sSWCNTs was high for pH 4 and 7 at low salt concentrations. At pH 2, the density of vertically adsorbed sSWCNTs was lowest since salt formation close to the isoelectric point (IEP) of the sSWCNTs. For measurements at pH values higher than the IEP of sSWCNTs, with the lower the ionic strength, the higher density of self-aligned sSWCNTs on the substrate was observed. This was also independent of the substrate used. It is suggested that the observed density dependence on ionic strength may be caused by a screening effect of the counter ions. Zeta potential measurements and colloidal stability of sSWCNTs dispersions are reported. Data strongly suggest that the density control of sSWCNTs is caused by screening via counter ions.

Nanometer-size iron-rich particles in carbon nanotubes have been studied by transmission electron microscopy with and without in situ and ex situ heating. Several remarkable results were found; a high temperature phase (γ-Fe) of iron stable at low temperatures and preferential presence of iron and iron carbide in carbon nanotubes. Based upon these experimental results, thermodynamics of the Fe–C phase diagram and its kinetics were used to explain the non-uniform distribution of iron and iron carbide, which also yielded a deeper insight into the formation of carbon nanotubes. Some of the results also allowed describing the role of the graphitic structure in retaining the high temperature phase (γ-Fe) of iron at low temperatures. Furthermore, methods have been demonstrated with which γ-Fe can be produced in carbon nanotubes intentionally or in a large quantity. Selected area electron diffraction patterns of iron inside nanotubes demonstrated the crystallographic relationship of the iron to the nanotube axis along with phase changes of the iron. This paper summarizes the findings and draws further conclusions on the particle shape inside multiwalled carbon nanotubes.

TiO 2 photocatalysis is currently being investigated as a viable technology to combat biological warfare agents such as anthrax spores. The current challenge in the use of photocatalysis for degradation of bacterial endospores is the time (in hours, as compared to minutes for bacteria) required for disinfection. The rate of disinfection can be increased by changing the rate of recombination of photon-generated electron-hole pairs and the rate of generation of reactive species. Modified photocatalysts has been synthesized by coating titanium dioxide, in anatase polymorph, on multi-wall carbon nanotubes (around 20 nm in diameter and 2–4 microns in length), for increasing the disinfection rate of bacterial endospores. Anatase coated multi-wall carbon nanotubes were tested for disinfection of Bacillus cereus spores (used as surrogate for anthrax spores) and the disinfection rate was shown to be twice as compared to the commercial titanium dioxide nanopowders, Degussa P25 (primary particle size of around 25 nm). These modified photocatalysts can also be used for selective disinfection of microorganisms depending on the surface morphology of the bacterial cell wall and the shape of the photocatalysts.

The rheological behavior of multiwall carbon nanotubes (MWCNTs) with polyelectrolyte dispersants (poly(acrylic acid) and poly(aspartic acid)) was investigated. The zeta potential of MWCNT slurries with adding dispersants and the optimum amount of dispersants for MWCNT slurries were measured. The Krieger–Dougherty equation was fitted to experimental data with varying solid loadings. The fitted results of MWCNT slurries showed the high intrinsic viscosity and the low maximum solid loading because of the high aspect ratio and the strong van der Waals force of MWCNTs. Poly(acrylic acid) stabilized MWCNT slurries had a lower maximum solid loading and a higher intrinsic viscosity ( ϕ m = 0.16, [ η ] = 43) compared to poly(aspartic acid) stabilized MWCNT slurries ( ϕ m = 0.21, [ η ] = 41.47). These differences may be caused by the different chemical structures of dispersants.

Crystallographic structures and orientations of nanoscale iron particles encapsulated in carbon nanotubes (CNTs) were studied with or without heat treatments at various temperatures. It was found from this study that γ-Fe with a face-centered-cubic crystal structure (known to be stable in the temperature range of 912–1394 °C for bulk iron) retains its stability in a large quantity at room temperature inside the cavities of CNTs. The relative number of γ-Fe particles was found to increase with temperature, especially with heat treatment at 1400 °C or higher. It was also found that iron particles in CNTs are oriented in specific crystallographic directions of their crystal structures along the axis of the nanotubes.

A novel biocidal photocatalytic nanocomposite, composed of TiO(2) and multi-walled carbon nanotubes (MWNTs), was synthesized via wet chemistry followed by a heat treatment. Uniform anatase coatings on MWNTs were successfully obtained with a thickness of a few nanometers. The nanostructure of the composite was determined by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The needle-like shape of the nanocomposite provided more than three times higher photocatalytic specific surface area than commercial TiO(2) nanoparticles (Degussa P25) when dispersed in water. Moreover, under ultraviolet (UV) radiation the excited electrons can be trapped at the interface between the TiO(2) layer and MWNTs and they can also be scavenged through the conductive graphitic layers. Thus, an intense photochemical reaction yielding a powerful biocide can be expected. Irradiating bacterial endospores (Bacillus cereus) with solar UV lamps in presence of the novel photocatalyst successfully inactivated the spores while solar UV lamps only or solar UV Lamps with Degussa P25 showed no significant inactivating behavior. Performance of photocatalytic nanocomposites was assessed based on time to achieve 90% inactivation of spores (LD(90)) and also in terms of time required to achieve a 1.0 log(10) reduction of spores in the tail region of the inactivation curve.

Multiwall carbon nanotubes (MWCNTs) were chemically oxidized in a mixture of sulfuric acid and nitric acid (3:1) while being ultrasonicated. The effect of oxidative ultrasonication at room temperature on development of functional groups on the carbon nanotubes was investigated. The dispersability and the carboxylic acid group concentration of functionalized MWCNTs (fMWNTs) varied with reaction time. The concentration of carboxylic acid groups on fMWNTs increased from 4 x 10(-4) mol/g of fMWNTs to 1.1 x 10(-3) mol/g by doubling the treatment period from 4 to 8 h. The colloidal stability of aqueous fMWCNTs dispersions was enhanced through elongated oxidation. fMWCNTs that were reacted longer than 4 h did not precipitate in aqueous media for at least 24 h. The layer-by-layer self-assembly of polyelectrolytes on fMWCNTs was characterized by zeta potential measurements. The zeta potential of fMWCNTs changed from negative charge to positive charge when cationic polyelectrolytes were self-assembled on their surface. With addition of anionic polyelectrolytes, cationic polyelectrolyte coated fMWCNTs showed the expected charge reversal as expected for multilayer self-assembly. Complex formation of positively charged gold nanoparticles and negatively charged fMWCNTs was achieved with and without polyelectrolyte coatings by electrostatic interaction. The complex formation was characterized by high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The here found complex formation of positively charged colloidal gold and defect sites on fMWNTs indicates the location of functional groups on carbon nanotubes. It is suggested that positively charged colloids such as gold nanoparticles could be used for detection of defect sites on carbon nanotubes.

Selective encapsulation of different materials or phases of a material inside a carbon nanotube leads to controlling local properties of the nanotube. We report a method of synthesizing stable γ-Fe selectively inside a carbon nanotube by transforming α-Fe through electron irradiation in situ inside a transmission electron microscope. Therefore, this method enables a single nanotube to encase both high (γ-Fe) and low (α-Fe) temperature phases of iron simultaneously. γ-Fe produced by this method may be used as a novel catalyst, and its presence inside a carbon nanotube may affect the physical properties of the nanotube, which therefore can be used to modify the nanotube.

In order to investigate the optimal conditions for highly orientated and epitaxial buffer layers on textured Ni tapes, we have deposited perovskite textured La2Zr2O7 (LZO) films on Ni tapes using a reel-to-reel sol-gel process for fabrication of second generation high-T-c superconductors. Of these usual parameters, precursor types, solvents, chelating agents, and annealing conditions were chosen to prepare LZO solutions. This effect on epitaxial growth of LZO of these processing and texturing parameters was evaluated using X-ray diffraction (XRD), environment scanning electron microscopy (ESEM), energy dispersive spectrometry (EDS) and orientation imaging microscope (OIM), atomic force microscope (AFM) and X-ray pole figure analysis. Based on the following results, we have found textured, homogenous, dense, crack free and pinhole free, LZO films with a strong c-axis orientation on textured Ni tapes by post-annealing at 1150degreesC for 10 min under 4% H-2-Ar gas flow. (C) 2003 Elsevier B.V. All rights reserved.

In this study, the morphology of zinc sulfide (ZnS) produced on carbon nanotubes (CNTs) by heat treatment was investigated. It was found that ZnS nanocrystals were formed on the outermost shells of CNTs in the shapes of ultrathin films, quantum dots, and nanorods. X-ray diffraction patterns show synthesized ZnS has the wurtzite structure. Hexagonal cross sections of some ZnS nanorods prove that they were grown along the 〈0 0 0 1〉 direction on the surface of CNTs. ZnS nanorods were synthesized without using any catalyst differently from the previous reports. Heterojunctions between CNTs by these ZnS nanocrystals were also found, which can be applied for nanosized optic and optoelectronic devices.

The crystallographic structure and orientation of iron nanoparticles present in carbon nanotubes (CNTs) was studied when iron was used as a catalyst. It was found that while most of the nanoparticles encapsulated inside the CNTs had the expected α–Fe (body-centered-cubic) phase, a significant number of them formed and retained the γ–Fe (face-centered-cubic) phase that is not the normal bulk phase at room temperature (nor even expected to form at the growth temperature used). It was also found iron particles at the tips of the nanotubes were either α–Fe or cementite (Fe3C). On the basis of these observations and thermodynamics, a mechanism for the formation of these particles and insights into CNT growth is proposed.

Surface forces acting between particles and different contributions to the forces are outlined with particular attention paid to the colloidal stability with nanosize particles. This is followed by a discussion of surface forces for nanosize particles and an introduction of a novel nanosize colloidal probe technique in an atomic force microscope.

In this research, preparation, structure, morphology and thermal properties of 4, 6, 8, 9 and 12 mole% CeO/sub 2/-ZrO/sub 2/ insulation coatings on Ag and/or AgMg/Bi-2212 superconducting tapes were studied for the magnet technologies. These coatings were prepared by reel-to-reel sol-gel method using a solution of Zr and Ce based precursors. The coatings were annealed at 850/spl deg/C for 24 h under oxygen gas flowing. The structure of coatings was characterized by SEM, EDS, TGA and XRD. The investigation showed that dense, fully cubic phase CeO/sub 2/-ZrO/sub 2/ insulation coatings with 8-10 Fm were deposited on Ag and/or AgMg/Bi-2212 superconducting tapes.

Properties of Carbon Nanotubes.- Electronic properties of Si and Ge pure and core-shell nanowires from first principle study.- Compositionally Graded III-nitride Nanowire Heterostructures: Growth, Characterization, and Applications.- Mechanical Characterization of Graphene.- Nanostructured ZnO materials: synthesis, properties and applications.- Nanosized gold and silver spherical, spiky and multi-branched particles.- Magnetite and other Fe-oxide nanoparticles.- Hierarchical Self-assembled Peptide Nano-ensembles.- Nanostructure Formation in Hydrogels.- Nanomanipulation and nanotribology of nanoparticles and nanotubes using atomic force microscopy.- Fabrication, properties and applications of gold nanopillars.- Stabilization and characterization of iron oxide superparamagnetic core-shell nanoparticles for biomedical applications.- Bio-inorganic nanomaterials for biomedical applications (Bio-silica and Polyphosphate).- Lipids as biological materials for nanoparticulate delivery.- Magnetic nanoparticles for biomedical applications.- Mechanical Properties of Nanostructured Metals.- Properties of Diamond Nanomaterials.- Sensing the mechanical properties of supported micro- to nano- elastic films.- Metal structures as advanced materials in Nanotechnology.- Metal oxide nanocrystals and their properties for application in solar cells.

A white precipitate is yielded on heating a solution of Y(NO3)3 (equivalent to 8 wt.% Y2O3), Al(NO3)3 (equivalent to 7 wt.% Al2O3 and molar ratio of 1:1.9378 for Y2O3 to Al2O3) and citric acid in isopropanol with a citrate–nitrate molar ratio of 0.098 to 60°C. The dried precipitate is then combusted at 200°C and produces a solid product (ash). X-ray powder diffraction patterns of the ash and its calcined forms show that the ash is amorphous and remains amorphous up to 600°C. The ash starts crystallizing to form a YAG phase at 800°C and completely transforms into YAG below 900°C. A certain amount of YAM phase co-exists with the YAG phase between 850°C and 900°C. Finally at 900°C, only the YAG phase exists. This combustion technique for synthesis of YAG phase can be used for incorporation of sintering additives in non-oxide ceramics such as Si3N4.

Nanostructured yttria powders were prepared by a gel combustion technique. The technique involves exothermic decomposition of an aqueous citrate-nitrate gel. The decomposition is based on a thermally induced anionic redox reaction. A variety of yttria powders with different agglomerate structures can be made by altering the citrate-nitrate ratio γ. The gel with γ = 0.098 in situ yields nanostructured yttria powder at 258 °C that is porous and agglomerated with an average of 25 nm primary particles. Its specific surface area is 55 m2/g. The decomposition of the gels was investigated by simultaneous thermogravimetry analysis (TGA) and differential thermal analysis (DTA) experiments. The produced ashes and calcined powders are characterized by x-ray diffraction (XRD), ir spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer, Emmett, and Teller (BET) analysis.

Lead zirconate titanate powders are derived from a novel aqueous-based citrate-nitrate/oxynitrate sol-gel combustion process. Aqueous solutions of metal nitrates or oxynitrates are transformed into gels with citric acid under heating. The received gels undergo a self-propagating combustion reaction on heating to 180 °C and subsequently yield voluminous ashes. These ashes form single phase perovskite Pb(Zr0.53Ti0.47)O3 powder with a specific surface area of 8 m2/g upon calcination at 550 °C. The ashes show a homogeneous distribution of lead, zirconium, and titanium ions which guarantees short diffusion paths in solid state formation of PZT perovskite. The redox behavior of the gels was studied with the help of DTA experiments. Powders are characterized in terms of XRD, SEM, and EDX analysis.

By use ofthe Langmuir-Blodgett (LB) technique mono- and multilayers of monomers and their polymers were built up on conductive solid substrates for studies with scanning tunneling microscopy (STM). Monomers, mixed monomers, and polymer monolayers of 3-alkylpyrroles were transferred onto freshly cleaved molybdenum disulfide (MoS 2 ) and highly oriented pyrolytic graphite (HOPG). High-quality images of the mono- and multilayers could be observed by STM after annealing. Monolayers of monomer were highly ordered showing orientational and positional correlation of alkyl side chains. Mixtures of pyrroles with different side chain lengths showed phase separation. Polymer monolayers showed high positional and orientational order and increased side chain packing density with side chain orientation more orthogonal to the surface. Polymer multilayers showed disorder, revealing connectivity and curvature of polymer chains. From the structures observed on solid substrates (gas-solid interface) conclusions are drawn for the polymerization process and the packing of molecules on the Langmuir trough (at the gas-liquid interface).

The nonfluorinated YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) coated conductors with 1-3 wt%Ag have been fabricated by sol-gel process. Ag doped YBCO films were fabricated on CeO/sub 2//YSZ/CeO/sub 2/ buffer layered Ni tapes by continuous sol-gel dip coating process. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analysis were used to characterize the YBCO coated conductor. The superconducting properties (T/sub c/ and J/sub c/) of Ag doped YBCO coated conductors were found to be higher than those of the un-doped conductors. The Ag doped YBCO has a T/sub c,zero/ of 88 K and J/sub c/ of 1.0/spl times/10/sup 5/ A/cm/sup 2/.

Laterally aligned carbon nanotubes were synthesized on substrates over iron nanoparticles using chemical vapor deposition. In addition, aligned carbon nanotubes grown vertically and with tilt angle to the substrates were produced, which means that it is possible to grow aligned carbon nanotubes at any angle relative to the substrate. The growth direction of the carbon nanotubes was controlled by a magnetic field that is applied in the process of adhering catalyst particles on silicon oxide substrates from dispersion. The ferromagnetic property of the iron nanoparticles fixes them in a defined orientation under magnetic field, which results in aligned growth of the carbon nanotubes. These results indicate that carbon nanotubes preferentially grow from certain facets of the catalyst particles, suggesting a crucial clue in investigating the growth mechanism of carbon nanotubes. The laterally aligned carbon nanotubes could make it possible to integrate them in nanoelectronic devices, such as a channel for field-effect transistors.

Magnesium batteries are alternatives to the use of lithium ion and nickel metal hydride secondary batteries due to magnesium's abundance, safety of operation, and lower toxicity of disposal. The divalency of the magnesium ion and its chemistry poses some difficulties for its general and industrial use. This work developed a continuous and fibrous nanoscale network of the cathode material through the use of electrospinning with the goal of enhancing performance and reactivity of the battery. The system was characterized and preliminary tests were performed on the constructed battery cells. We were successful in building and testing a series of electrochemical systems that demonstrated good cyclability maintaining 60-70% of discharge capacity after more than 50 charge-discharge cycles.

The anatase phase of TiO2 has been of great interest due to its photocatalytic activity. For enhanced photocatalytic activity, the polymorphic structure of anatase phase and the rutile phase was pursued to form the semiconductor-semiconductor junction, which could even further enhance photocatalytic activity. TiO2 nanofibers with large specific surface area were fabricated via electrospinning from ethanol-based sol while the phase development was controlled by heat treatment. TiO2 fibers were characterized by x-ray diffraction (XRD) and transmission electron microscopy (TEM) for the crystalline phase and its microstructure, respectively. Among different heat treatment temperatures tested, 700°C was found to have the smallest grains while having both semiconductor, i.e. rutile and anatase available. TiO2 calcined at 800°C also achieved the polymorphic structure of anatase and rutile phases, however showed significant grain growth.

This project aims to develop a RHELP (Regenerative-High Efficiency-Low Pressure) air purification system using a novel ceramic nanofiber on silicon carbide in a microwave oxidizer that can effectively decontaminate air containing aerosolized chemical and biological (CB) agents. Nanofibermats of several materials were designed and fabricated using electrospinning process. Physical filtration testing showed performance (filter quality) exceeding military HEPA requirement. Multiple layers were found to have better filter quality than single layer of the same thickness. Biological agent testing showed effectiveness of microwave irradiation to deactivate a wide range of biological agents. System performance can be further enhanced by lowering face velocity during periodic microwave irradiation to minimize heat loss. Chemical agent testing showed excellent regeneration but destruction of the agent needs further improvement.

A novel approach is presented to synergistically enhance photocatalytic activity in a nanocomposite using the high aspect ratio of carbon nanotube (CNT) and their unique electrical properties. Composite nanoparticles were synthesized with sol-gel nano-coating on multi-walled carbon nanotubes (MWNTs). The nanostructure was characterized using SEM, TEM, XRD, Raman, FTIR and UV-VIS spectroscopies. Photocatalytic efficiencies of commercial photocatalysts (Degussa P25) and TiO2 nano-coated MWNTs were evaluated by Azo dye degradation tests. Superior photocatalytic activity was observed for the nanocomposite with UV-A and with visible light only irradiation.

Textured growth of Cerium oxide (CeO2) and 100% lattice matched (Eu0.893Yb0.107)2O3 buffer layers were investigated for YBCO coated conductors as cap layers on Gd2O3 thin films by chemical solution deposition technique. CeO2 is one of the most widely used cap layer for fabrication of coated conductors, especially when e‐beam evaporation technique is used for YBCO processing. (Eu0.893Yb0.107)2O3 was designed as a perfect lattice matched cap layer, and CeO2 and (Eu0.893Yb0.107)2O3 cap layers have been fabricated on biaxially textured Ni substrates by chemical solution deposition technique in our laboratory. This time we presented textured growth of CeO2 on a Gd2O3 thin film and textured growth of (Eu0.893Yb0.107)2O3 on the CeO2/Gd2O3/Ni buffer layers structure by chemical solution deposition technique.

High temperature ZrO2 based coatings were deposited on Ag and Ag/AgMg sheathed Bi-2212 tapes from solutions derived from alkoxide-based precursors using a reel-to-reel, continuous sol-gel technique. The insulation coatings were annealed at 850 °C for 20 hours under O2 flow. The surface morphology and structure of coatings were characterized by SEM and XRD. High voltage breakdown of insulation on tapes was measured by a standard high voltage breakdown power supply. It has been found that high voltage breakdown values of these insulations strongly depend on number of dipping, thickness, coating type, annealing conditions, and dopant content in ZrO2. 20% Y2O3-ZrO2 coatings showed the best high voltage breakdown value, 2.05 kV at 1.5 mA.

YBCO coated conductor development on Ni tapes with various sol-gel buffer layers were investigated by a continuous, reel-to-reel sol-gel technique. YBCO films were prepared using solutions of various Y, Ba, and Cu precursor organometallic compounds. The coated YBCO tapes were annealed under argon/oxygen flow. ESEM, EDS, and XRD analysis were used to characterize the YBCO films. Sol-gel YBCO coated conductor on sol-gel buffered Ni tapes yielded a Tc,onset of 90 K and Jc of about 105 A/cm2. The films produced in this manner were homogeneous, and free of cracks.

Nickel tapes which were cold rolled to large deformation and annealed to produce a cube texture were used as substrates for YBCO coated conductor development. In this study the cold rolled Nickel was annealed in 4%H2-Ar at 800 °C, 850 °C, 900 °C, 950 °C, 1000 °C, and 1050 °C for various times. After annealing, grain size and grain boundary (GB) grooving measurements were carried out by means of metallography and atomic force microscopy (AFM). X-ray and pole figure measurements were done for all samples. Phi and Omega scans were performed for each sample to determine the degree of the in plane and out of plane texture. The Ni tape was 95% cube textured, after optimum annealing.

Bi-axially textured Ni tapes were oxidized to form NiO as alternative buffer layers for sol-gel YBCO coated conductors. We investigated growth and stability of YBCO films on nickel oxide buffer layers without using a cap layer. Microstructure of NiO, and effects of the microstructure on the properties of YBCO were also examined. To understand microstructure formation of NiO layers, parameters of surface oxidation process such as oxidation time, temperature and atmosphere were studied. Surface morphology, thickness of NiO and YBCO layers, were studied using environmental scanning electron microscopy (ESEM). We found that surface oxidation parameters strongly affect microstructure, thickness, and morphology of NiO, and the properties of YBCO. Resistance versus temperature measurements of YBCO coated conductors was done by 4-probe measurements.

Anatase TiO2 nanoparticles with a size range of 2 to 10 nm have been formed on carbon nanotubes by the controlled hydrolysis and condensation of titanium bis-ammonium lactato dihydroxide in water and electrosterically dispersed carbon nanotubes.

The family of techniques known as scanning probe microscopy (SPM) was invented in 1981 by Binnig and Rohrer. The most common methods are scanning-tunneling microscopy, atomic-force microscopy (AFM), and near-fi eld scanning optical microscopy, although hundreds of other variants have since been developed. Regardless of the specifi c version, each applies the same basic concept: detecting interactions between a scannable nanoscale probe and a nearby surface in order to measure and/or map local surface properties. Atomic-force microscopy was designed for detecting and mapping tipsample forces. These include repulsive and attractive interactions such as van der Waals, electronic, and magnetic forces, though applications to detect chemical, thermal, acoustic, and a host of other properties have since been implemented. The concept also extends to lithography, whereby the probe is used to modify a surface through physical, electronic, chemical, or thermal means. The probe itself in AFM is generally a microfabricated tip at the end of an integrated cantilever. Static or intermittent contact forces between the tip apex and a surface are measured as corresponding shifts in the lever defl ection or the resonant frequency, respectively. Although the lever motion is generally nanoscale, it is nearly always amplifi ed by refl ecting focused light off of the lever The Application of Scanning Probe Microscopy in Materials Science Studies