The study of nano-cylinder structure has attracted much attention due to the application of multi-wall carbon nanotubes (MWCNTs). While some TEM observations indicate that they are formed by seamless concentric cylinders, other TEM and high pressure X-ray diffraction studies suggest that they look like scrolls of graphite sheets. Although many people now accept the concentric cylinder model, there has been no confirmation reported. On the other hand, this structural difference of MWCNTs plays a crucial role in determining the properties and suitability for future applications. For example, the periodical boundary condition can only be imposed for cylinders, but not for scrolls. To resolve this issue, we employed high-resolution X-ray diffraction to measure detailed profiles of the Bragg peaks for high-purity MWCNTs. We then identified some unusual observations unique to the nano-cylinder structure, followed by the analysis of the structural difference in the Fourier transform between nanotubes formed by scrolls and concentric cylinders. The simulation results are then compared with the experimental data to reveal the structural details.

Stable sols of 60 nm colloidal zirconia have been prepared by thermolysis of zirconium acetate. The surface complexing acetate groups have been replaced by phosphoric acid groups. Phosphate grafting has been characterized by dynamic light scattering, infrared spectroscopy, 31P nuclear magnetic resonance and impedance spectroscopy measurements. These systems give acid and proton conductive particles (4.10-5 S.cm-1 at 70 % relative humidity).

H3PO4/ZrO2/PVDF-co-HFP composite membranes have been synthesized. Impedance spectroscopy measurements allow discrimination between proton conduction at the surface of the phosphated particles and within free H3PO4 in the polymer. For the highest H3PO4/ZrO2 ratios, the latter phenomenon prevails, giving a proton conductivity of 6.10-4 S.cm-1 at 70 % R.H.

Ion implantation and thermal processing were used to create a layer of Co nanoclusters embedded in the near-surface region of single-crystal sapphire. The Co nanoparticles ranged in size from 2-20 nm and were crystallographically aligned with the host sapphire. Specimens were irradiated with Xe and Pt ions, and the microstructural evolution of the nanoclusters was investigated by transmission electron microscopy. With increasing Pt or Xe ion dose, the Co nanoparticles lost their initially excellent faceting, although they remained crystalline. The host Al2O3 became amorphous and the resulting microstructure consisted of a buried amorphous layer containing the still-crystalline Co nanoparticles. EDS mapping and electron diffraction were used to determine the distribution of the implanted species, and the magnetic properties of the composite were measured with a SQUID magnetometer. The results show that ion beams can be applied to modify and control the properties of ferromagnetic nanocomposites, and, combined with lithographic techniques, will find applications in exercising fine-scale spatial control over the properties of magnetic materials.

Noble gases are generally very insoluble in solids. For example, Xe implanted into Al at 300 K forms a fine dispersion of crystalline precipitates and, at large enough fluence, fluid precipitates, both of which are stabilized, relative to the gas phase, by the Laplace pressure due to precipitate/matrix interface tensions. High resolution electron microscopy has been performed to determine the largest Xe nanocrystalline precipitate in local equilibrium with fluid Xe precipitates within the Al matrix. From the shape and size of the largest crystal and the Laplace pressure associated with its interface, we show that the interface tensions can be derived by setting the Laplace pressure equal to the pressure for solid/fluid Xe equilibrium derived from bulk Xe compression isotherms at the temperature of equilibration and observation. The Xe/Al interface tensions thus derived are in the range of accepted values of surface tensions for the Al matrix. Furthermore, it is suggested that this same technique may be employed to estimate unknown surface tensions of a solid matrix from the size and shape of maximal nanocrystals of a noble gas element, which have been equilibrated in that matrix at the temperature of observation.

Various layered hybrid films prepared from organoalkoxysilanes with long organic chains, based on the self-assembly of the hydrolyzed species, are reviewed. Morphological control of transparent and oriented films was achieved by cohydrolysis and polycondensation with tetraalkoxysilanes, followed by dip- or spin-coating. In addition to alkyltrialkoxysilanes, alkyldimethylmonoalkoxy- and alkylmethyldialkoxy-silanes were also used as the structural units, implying that the inorganic-organic interface can be designed at a molecular level. In these cases, co-condensation in the precursor solution plays an essential role in the formation of homogeneous and ordered films. Alkenyltriethoxysilanes with terminal C=C bonds were also employed to prepare layered hybrid films. Interlayer chains were polymerized upon UV irradiation, and the resulting films exhibited a significant increase in the hardness if compared with the films before polymerization. Hybrid films thus obtained are a new class of materials and of great interest for a wide range of materials chemistry.

Tetramethyl ammonium silicate (TMAS) is known as a structuring agent in zeolite synthesis. We report its first use to prepare porous silica films for low k dielectric applications in microelectronics. A solution of TMAS 18.7 wt. % was spin coated on silicon substrates with a 3000 Å thick thermal oxide. The spin coated films were subsequently heat-treated at 450°C to obtain porous silica. The use of TMAS solution without gelation led to films of only moderate porosity value of 10%. The addition of methyl lactate, a gelling agent, significantly increased film porosity and improved the pore size distribution. For example, 50% porosity and uniform pore size distribution (average pore size ∼ 40 Å) has been achieved. Dielectric constants (k) of our porous films are as low as 2.5.

Nanocrystalline lead titanate was synthesized by reacting nanocrystalline titanium oxide in aqueous solutions of potassium hydroxide and lead acetate at 200 degrees C. X-ray diffraction (XRD) and TEM studies suggest that the initial KOH concentration influenced the nucleation and growth behavior of the lead titanate nanoparticles. Powders were processed in aqueous solutions containing 0.10 M lead acetate and a Pb:Ti ratio of 1, with varying concentrations of KOH. Powders processed in 0.01 M KOH were composed of irregularly shaped particles with 50-100 nm in size, processing in 0.10 M KOH produced particles with finger-like morphology and broader particle size distribution, and processing in 1.0 M KOH resulted in anisometric plates with (001) facets, and 100-200 nm in size. XRD studies have shown systematic variations in the position and symmetry of reflections with a l component as a function of particle size. This indicates that the c/a ratio of lead titanate increases with decreasing nanoparticle size

Highly reflective surface-metallized flexible polyimide films have been prepared by the incorporation of the soluble silver ion complex (1,1,1-trifluoroacetylacetonato)silver(I) into dimethylacetamide solutions of the poly(amic acid) prepared from 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA) and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoro-propane (4-BDAF). Thermal curing of solution cast silver(I)-poly(amic acid) films leads to cycloimidization of the amic acid with concommitant silver(I) reduction and formation of a reflective surface-silvered film at 8 and 13 weight percent silver. The metallized films are thermally stable and flexible with mechanical properties similar to those of the parent polyimide. TEM reveals that the bulk (interior) of the polyimide composite films have 5-20 nanometer-sized silver particles with a surface layer of silver metal ca. 80 nm thick. Neither the bulk nor the surface of the films is electrically conductive. Adhesion of the surface metal to polyimide is excellent.

Nanocrystalline SnO2 and WO3 and nanocomposite with Sn:W ratio 1:9, 1:1, 9:1 were prepared by co-precipitation of α-stannic and tungstic acids. Phase composition and average crystallite size were determined from XRD data. Presence of the second component results in the reduction of the crystallites growth rate, giving rise to the enhancement of thermal stability of nano-scaled system. TGA data allowed to estimate the concentration νH2O of water adsorbed on nanocomposite effective surface. Maximal νH2O value and the highest resistance were observed for nanocomposite with Sn:W = 1:1. The temperature dependence of resistance R reveals its activation character. The current-voltage curves are interpreted in terms of electrochemical capacitor recharge.

Chromium nitride films CrNx with x ranging form 0 to 1 were deposited by reactive PVD. Both stress and hardness in the films are a function of the composition. The growth stress and hardness for the majority of the films can be related through the Hall Petch relation. It is shown that the hardest films fall outside this relation. It is also shown that the hardest films are nanocrystalline. It is argued that the hardness of these films is a consequence of the nanocrystallinity of these films.

Three dimensional Ni and NiO inverse opal macromeshes were characterized by scanning electron microscope (SEM) and transmission electron microscope (SEM). The octahedral cubes of the macroporous Ni were found mostly grown as single crystals with staking faults and microtwins. There was no preferential growth of these cubes as determined by selected area diffraction pattern (SADP). Some NiO nanocrystals with size of about 5 nm were formed on the surface of inverse Ni opal membrane during etching away of silica spheres. The oxidation of Ni mesh turned it into NiO macromesh with grain size of about 20 nm at 550°C. The nanocrystalline NiO mesh is suitable for further fabrication of three dimensional nanobeads. By annealing the meshes at 650°C, the NiO nanograins grew to a size of over 50 nm. This three dimensional ordered macroporous structure with higher temperature treatment is considered as stable and important for further application.

Epoxy nanocomposites were prepared from the montmorillonite after organic treatment with a high Tg epoxy resin (Shell Epon 862 and curing agent W). Investigation of the rheological characteristics showed that the addition of clay to the resin did not significantly alter the viscosity or cure kinetics and that the modified resin would still be suitable for liquid composite molding techniques such as resin transfer molding. DSC was performed to study the kinetics of the curing reactions in the modified resin. An in situ small-angle x-ray scattering (SAXS) experiment was used to try to understand the structural development during cure. Based on the in situ SAXS data, structural changes were monitored in real time during cure and analyzed. Results from wide-angle x-ray diffraction, SAXS, and transmission electron microscopy of the polymer-silicate nanocomposites were used to characterize the morphology of the layered silicate in the epoxy resin matrix. The glassy and rubbery moduli of the polymer-silicate nanocomposites were found to be greater than the unmodified resin due to the high aspect ratio and high stiffness of the layered silicate filler. The solvent absorption in methanol was also slower for the polymer-silicate nanocomposites.

Annealing of nanodiamond at moderate temperature makes it possible to produce structures being intermediate in the carbon transformation from sp3- to sp2-state (graphite/diamond nanocomposites) and onion-like carbon (OLC). Electron microscopy shows such structures involve cage shells with spacing close to graphite. X-ray emission spectroscopy has been applied to examine the electronic structure of OLC and graphite/diamond nanocomposites. The CKα-spectra of OLC produced in the temperature range of 1600-1900 K were found to be markedly different from the spectrum of particles formed at 2140 K and characterized by better ordering of graphitic shells. The latter spectrum was shown to be very similar to the CKα-spectrum of polycrystalline graphite, while the former ones exhibited a significant increase of high-energy maximum that might be caused by the holed defect structure of graphitic networks forming at the intermediate annealing temperatures. To interpret experimental spectra, the quantum-chemical semiempirical AM1 calculation of icosahedral C540 cage and that with holed defects was carried out. The lack of at least 22% atoms in an internal carbon cage was found to be essential to provide an increase of density of high-energy electronic states similar to that observed in the spectrum of OLC produced at 1900 K.

Optical non-linearity of cobalt oxide with SiO2-TiO2 additives was investigated, and the change mechanism of the refractive index (n) and extinction coefficient (k), based on the relation between band structure and optical non-linearity of the thin films, was discussed. Refractive index and extinction coefficient of Co3O4 thin films in the ground state were 3.17 and 0.42, respectively. Both n and k decreased by irradiation from a pulse laser with 650 nm of wavelength (1.91eV). These values in the excited state were 2.91 and 0.41, respectively. n2 estimated from the change of n and k was −2.8 ×10−11 m2/W. The film had a band gap corresponding to 2.06eV, indicating that it was widened by the band filling effect during the laser irradiation at 1.91eV, and this led to the decrease in absorption coefficient and refractive index.

The band energy structure of large-sized (10-25) nm nanocrystallites (NC) of SiCxO1-xN (0.96<x<1.06) was investigated using different band energy approaches, as well as modified Car Parinello molecular dynamics simulations of interfaces. A thin carbon sheet (of about 1 nm) appears, covering the crystallites. This sheet leads to substantial reconstruction of the near-the-interface SiCxO1-xN crystalline layers. Numerical modeling shows that these NC may be treated as quantum dot-like SiCxO1-xN reconstructed crystalline surfaces, covering the appropriate crystallites. All band energy calculation approaches (semi-empirical pseudopotential, fully augmented plane waves and norm-conserving self-consistent pseudopotential approaches) predicted the experimental spectroscopic data. In particular, it was shown that the near-the-surface carbon sheet plays a dominant role in the behavior of the reconstructed band energy structure. Independent evidence for the important role of the dot-like crystalline layers are the excitonic-like states, which are not dependent on the particular structure of the SiC, but are sensitive to the thickness of the carbon layer.

Gd3+ doped Ce oxides are a major candidate for use as the electrolyte in solid oxide fuel cells operating at ∼500 °C. Here, the effect of the atomic structure on the local electronic properties, i.e. oxygen coordination and cation valence, at grain boundaries in the fluorite structured Gd0.2Ce0.8O2-x ceramic electrolyte is investigated by a combination of atomic resolution Z-contrast imaging and electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). In particular, EELS analyses from grain boundaries reveals a complex interaction between segregation of the dopant (Gd3+), oxygen vacancies and the valence state of Ce. These results are similar to observations from fluorite-structured Yttria-Stabilized Zirconium (YSZ) bicrystal grain boundaries.

It has been clearly demonstrated that ATP could be intercalated into inorganic layered double hydroxide (LDH), giving rise to a biomolecular-inorganic nanohybrid with preserving its physico-chemical and biological integrity. It shows a remarkable transfer efficiency of ATP into target cells by alleviating an electrical repulsion at the cell walls due to the neutralization of negative charge of phosphates by positive hydroxide layers. From cellular uptake experiment with laser scanning confocal fluorescence microscopy, it is revealed that the FITC-LDH hybrid is effectively transferred into 293 cells. Such an unique feature of biomolecule-LDH hybrid will open a new field of reserving and delivering genes, drugs and other functional biomolecules.

SAXS and EXAFS were applied to study genesis of polynuclear zirconium hydroxyspecies in pillaring solutions as dependent upon the zirconium concentration, addition of alkaline-earth chlorides and aging. After the montmorillonite clay pillaring, the structure of zirconium nanopillars was characterized by applying X-ray structural analysis, UV-Vis, FTIRS of adsorbed CO and nitrogen adsorption isotherms. Main pillaring species appear to be nanorods comprised of several Zr4 tetramers. Basic structural features of the tetramers are preserved in zirconia nanoparticles fixed between alumosilicate layers in pillared clays. In calcined samples, those nanoparticles contain only bridging hydroxyls and/or oxygen anions responsible for bonding within pillars and between pillars and clay sheets.

Large scale of straight Ga2O3 nanowires is grown on a fused silica substrate by a simple catalyst-free CVD method using Ga metal and N2 / H2O reactants. The Ga2O3 nanowires with diameters ranging from 60 to 150 nm can be as long as several micrometers. XRD and TEM analyses indicate that the Ga2O3 nanowires exhibit a monoclinic structure. PL characteristic of the Ga2O3 nanowires shows a UV emission of 375 nm at room temperature.

This report presents a novel synthesis method of alumina nanofibers at moderate conditions in aqueous systems through a surfactant-directed crystal growth process. In the presence of polyethylene oxide (PEO) surfactants, boehmite nanofibers of about 3 nm thick and 30-60 nm long formed from aluminium hydrate colloids. During the subsequent heating, the surfactant was evaporated and boehmite nanofibers were converted into γ-alumina nanofibers. The function of the PEO surfactant and the formation mechanism of the nanofibers are discussed. Alumina nanofibers are an ideal structural reinforcement for various nanocomposite materials. They are potential adsorbents with high adsorption capacity. Furthermore, their unique structure exhibits strong resistance to heating at high temperatures. The BET surface area of a typical sample after heating at 1200°C is as high as 68 m2/g. This makes the material very promising as excellent substrates for catalysts of high thermal stability.