TiO2 nanoparticles with interesting physicochemical properties were synthesized by means of the sol-gel method and acid hydrolysis. The obtained nanoparticles were characterized by the X ray diffraction (XRD), Rietveld refinement, Brunauer Emmett Teller (BET) and transmission electron microscopy (TEM) techniques, and tested in the photodecomposition of NOx. The NOx decomposition degree reached by the sol-gel TiO2 nanoparticles was directly proportional to the brookite mass fraction, but inversely proportional to both the anatase mass fraction and the crystal size.

A new shift register using p-type poly-Si thin-film transistors (TFTs) for active matrix display is proposed. It utilizes only p-type TFTs to simplify the fabrication process, and provides time-shifted output signals with a voltage swing from VSS to VDD without signal-level loss. In the proposed shift register, output is structurally separated from carry and therefore has a high immunity to output signal distortion caused by output load capacitance. We also propose a new light emitting control method using this shift register for high image quality active-matrix organic light emitting diode (AMOLED) displays. The proposed shift register was verified by simulation and measurement.

We analyze the dependence of the interface defect density Dit in amorphous/crystalline (a-Si:H/c-Si) heterostructures on the microscopic properties of the ultrathin (10nm) undoped a-Si:H films. It is shown that the hydrogen bonding configuration, probed by infrared spectroscopy, determines the a-Si:H network disorder, which in turn governs the annealing behavior of these structures upon a short thermal treatment at moderate temperatures (T ≤ 200°C). While the as-deposited Dit seems to be determined by the local structure at the interface, the final state of the annealed samples is determined by the bulk a-Si:H network strain as reflected in the valence band tail slope. Thus it appears valid to treat the equilibrated a-Si:H/c-Si interface as a 2D-layer that has the projected defect properties of the 3D a-Si:H bulk.

We study theoretically the electronic structure and photoemission spectra of PuCoGa5 making use of the LDA+Hubbard I approximation implemented in the full-potential LAPW basis, including self-consistency over the charge density. The calculations show relative reduction of the f-states spectral weight at the Fermi energy. There is fairly good agreement between calculated photoemission spectra and experimental results. We demonstrate that an account of Pu f-electron Coulomb correlations does not modify significantly the Fermi surface topologies but leads to substantial reduction of the f-character for the electronic states at the Fermi energy. These findings can be important for the theory of superconductivity in PuCoGa5 and related compounds.

LPCVD Ge films are deposited onto bulk Si substrates and subjected to either a rapid thermal anneal (RTA) or furnace anneal (FA) at a temperature that is higher than the melting point of Ge in an attempt to induce epitaxial recrystallization. Spiking into the Si and voids in the Ge film are observed after the anneal. This is attributed to defect-assisted Ge diffusion into the Si substrate caused by strain at the Ge-Si interface. Simple diffusion theory using published diffusivity values predicts diffusion depths similar to the spiking depths observed by scanning electron microscopy and transmission electron microscopy. Approaches to reduce the strain at the interface are explored. It is found that the quasi-equilibrium nature of FA reduces spiking and that there is an area dependence. Grazing-incidence x-ray diffraction analysis suggests that this technique for epitaxial recrystallization does not result in single-crystalline Ge.

We describe a novel, facile method for the alignment of multi-walled carbon nanotubes (MWNTs) in a magnetic field facilitated by the decoration of the MWNTs with monodisperse γ-Fe2O3 magnetic (maghemite) nanoparticles. The tethering of the nanoparticles was achieved by the attachment of γ-Fe2O3 nanoparticles that were synthesized using a modified sol-gel process, onto the carboxylate-activated MWNTs. Sodium dodecylbenzene sulfonate (NaDDBS) was used to prevent the formation of an iron oxide 3D network. Various characterization methods were employed to confirm the formation of homogeneously-distributed and nearly-monodispersed iron oxide nanoparticles, and show that they were indeed tethered to the walls of the MWNTs. The γ-Fe2O3 nanoparticles imparted magnetic characteristics to the MWNTs, which in turn, were oriented parallel to the direction of an externally-applied magnetic field. This facile alignment of MWNT could promote the enhancement of various properties, e.g. mechanical and electrical properties, of the resulting composites. Moreover, this facile alignment at low magnetic fields, made possible by the magnetization of the carbon nanotubes through the tethering of maghemite nanoparticles, may be applied to a variety of other useful nanofillers, such a glass fibers, clay nanoparticles and cellulose nanowhiskers.

This research contributes to the study of hydrogen storage of two Ti-Zr based systems using (I) titanium dioxide (TiO2) + zirconium acetylacetonate (C20H28O8Zr) and (II) titanium dioxide (TiO2) + zirconium tetrachloride (ZrCl4) as starting materials. Both systems were prepared by mechanical grinding under the same conditions, with composition of 50 wt.% Ti and Zr and milling time of 2, 5, 7, 15, 30 and 70 hrs. The samples were evaluated by hydrogen absorption tests and characterized by BET, XRD and TEM. The results of hydrogen storage at different pressures but same temperature showed that samples of the system I absorbed the largest quantities of hydrogen but difficult to release them, while the system II absorbed less amount of hydrogen but completely desorbed the absorbed hydrogen. The increase of the mechanical grinding time is directly associated with changes in hydrogen absorption capacity and formation of new components. The formation of oxide nanoparticles of Ti and Zr on the surface of TiO2 in samples from series II was associated with the hydrogen absorption capacity. Keywords: hydrogen storage, Ti-Zr, mechanical milling, sorption.

We examine the electronic structure of δ-Pu, PuCoGa5, and PuO2 using high resolution as well as angle-resolved photoelectron spectroscopy. The fermiology of the strongly correlated metals δ-Pu and PuCoGa5 is investigated by determining the primary quasiparticle peak position with respect to the Fermi energy as well as the crystal momentum dependence of this peak for PuCoGa5. For the Mott insulator PuO2, the photoemission results are compared against the hybrid functional calculations and the prediction of significant covalency, is found to be reasonable.

The strength and electrical conductivity of Carbon Nanotube (CNT) yarns is dramatically affected by the handling of the material after the nanotubes are produced. Our nanotube production process involving Chemical Vapor Deposition (CVD) using the floating catalyst method produces a mass of entangled bundles of single-walled nanotubes in a gas suspension. Simply collecting and spinning this material produces a yarn with strength and electrical conductivity far less than the properties of the individual nanotubes due to the poor alignment of the bundles on the microscopic scale. We have developed methods of aligning the CNT material that are analogous to the techniques used in the textile industry for spinning staple yarns, but modified to be appropriate for nano-scale material. The result is a dramatic improvement in strength and electrical conductivity of our CNT yarns.

The successful implementation of silicon nanowire (NW)-based tunnel-field effect transistors (TFET) critically depends on gaining a clear insight into the quantitative carrier distribution inside such devices. Therefore, we have developed a method based on scanning spreading resistance microscopy (SSRM) which allows quantitative two-dimensional (2D) carrier profiling of fully integrated NW-based TFETs with 2 nm spatial resolution. The keys in our process are optimized NW cleaving and polishing steps, in-house fabricated diamond tips with ultra-high resolution, measurements in high-vacuum and a dedicated calibration procedure accounting for dopant dependant carrier mobilities.

This study describes the influence of the processing parameters on the structure of a Diamalloy 1008 (Fe-Cr-Mo alloy) coating applied with high velocity oxi-fuel (HVOF) on steel tool grade samples D2. This coating is commonly use as a protection against corrosion and wear, but it also has the capacity to recover damaged areas as die stamping for automotive stamp. An experimental statistic design identify the fuel velocity and oxygen flow as well as the pulverization distance as the most influential parameters that control the powder particles characteristics when it’s being sprayed (“in trajectory”) before impact. The effects of these parameters in porosity level, oxide content and micro-hardness were investigated in detail. Metallographic tests are used to evaluate the deposited material adhesion quality, the SEM technique is use to evaluate the material porosity in the substrate adhesion and the damage in the tools.

We present molecular dynamics simulations using both empirical potentials (EP) and density functional theory (DFT) on ion irradiation of graphene. The comparison between the two methods shows that EP gives not only qualitatively but also quantitatively reasonable estimates of defect production during ion irradiation in carbon nanosystems. Ion irradiation is shown to give rise to a range of interesting defects e.g. single, double and triple vacancies, bond rotations, close-by Frenkel pairs and more complex defect structures. We show that the creation of these defects is related to the atomic processes upon the ion impact, and define the critical irradiation angles both for maximum damage and no penetration as a function of the ion mass.

The influence of the location of the embedded a-Si:H layer in the gate dielectric film of the floating-gate a-Si:H TFT on the charge trapping and detrapping mechanisms has been investigated. The thin channel-contact SiNx gate dielectric layer favors both hole and electron trappings under the proper gate voltage condition. The sweep gate voltage affect the locations and shapes of forward and backward transfer characteristics curves, which determines the memory function. In order to achieve a large memory window, both the location of the embedded a-Si:H layer and the gate voltage sweep range need to be optimized.

In this work, the effect of elevated temperature on the generated defects with constant voltage stress (CVS) in SiO2 and SiO2/HfSiO stacks is investigated. Applying Trap Spectroscopy by Charge Injection and Sensing (TSCIS) to 6.5 nm SiO2 layers, different kinds of generated traps are profiled at low and high temperature. Also the Stress-Induced Leakage Current (SILC) spectrum of high-k dielectric stack is different at elevated temperature indicating that degradation and breakdown at high temperature is not equivalent to that at low temperature and therefore, extrapolation of data from high to low T or vice versa is challenging.

Cu-Li-Mg-(H,D) was studied as an example of destabilizer of the Ti-(H,D) system. A Cu-Li-Mg alloy was prepared resulting in the formation of a system with 60.5 at% of CuLi0.08Mg1.92, 23.9 at% of CuMg2 and 15.6 at% of Cu2Mg. Titanium was added to a fraction of this mixture so that 68.2 at% (47.3 wt%) of the final mixture was Ti. The mixture was ground and kept at 200 °C/473 K for 7h under H2 or 9h under D2 at P = 34 bar. Under those conditions, neutron powder diffraction shows the formation of TiD2, as well as of the deuteride of CuLi0.08Mg1.92. Similarly inelastic neutron scattering shows that at 10 K TiH2 is present in the sample, together with the hydride of CuLi0.08Mg1.92. Interestingly, at 10 K TiH2 is very clearly detected and at 300 K TiH2 is still clearly present as indicated by the neutron vibrational spectrum, but CuLi0.08Mg1.92-H is not detected anymore. These results indicate that Ti(H,D)2 is possibly formed by diffusion of hydrogen from the Cu-Li-Mg-(H,D) alloys. This is an intriguing result since TiH2 is normally synthesized from the metal at T > 400°C/673 K (and most commonly at T ˜ 700 °C/973 K). In the presence of CuLi0.08Mg1.92, TiH2 forms at a temperature that is 300 – 400 K lower than that needed to synthesize it just from the elements.

We report synthesis of the sodium cobalt oxide γ-NaxCoO2 submicron tubules using the citric acid-based sol-gel route with the assistance of commercial porous anodized aluminium oxide (AAO) membrane with a nominal pore size of 200nm as supporting templates. The γ-NaxCoO2 submicron tubules can be obtained at 500°C using a rapid-heat-up procedure and held for 30 min. The submicron tubules have a diameter of 200-250 nm. The products are investigated using various techniques including powder x-ray diffraction, field emission scanning electron microscope and transmission electron microscope. The atomic ratio of Na/Co of theγ-NaxCoO2 submicron tubules is determined using energy dispersive x-ray spectra. The atomic ratio of Na/Co tends to be less than 0.5 due to the tendency of Na+ de-intercalating from its parent structure during the tubules collecting process.

Nano- and hetero-structures of carbon nanotube (CNT) and indium tin oxide (ITO) can control significantly piezoelectric and optoelectronic properties in Microelectromechanical Systems (MEMS) as sensing and actuators under cyclic loading. Optimized preparation conditions were obtained for multi-functional purpose of the specimens by obtaining the best dispersion and turbidity in the solution. Optical transmittance and electrical properties were investigated for CNT and ITO dipping and spraying coating on boro-silicate glass and polyethylene terephthalate (PET) substrates by electrical resistance measurement under cyclic loading and wettability test. Uniform dipping coating was performed using Wilhelmy plate method due to it simple and convenience. Specimen was applied with spraying coating additionally. The change in the electrical and optical properties of coated layer is mainly dependent upon the number of dip-coating, the concentration of CNT and ITO solutions, and the surface treatment condition. Electric properties of coating layers were measured using four-point probe method, and surface resistance was calculated using a dual configuration method. Optical transmittance of CNT and ITO coated PET film was also evaluated using UV spectrum. Surface energy and their hydrophilic and hydrophobic properties of CNT and ITO coated substrates were investigated by wettability test via static and dynamic contact angle measurements. As the elapsing time of cyclic loading passed, the stability of surface resistance and thus comparative interfacial adhesion between coated layer and substrates was evaluated to compare the thermodynamic work of adhesion, Wa . As dip-coating number increased, surface resistance of CNT coating decreased, whereas the transmittance decreased step-by-step due to the thicker CNT and ITO networking layer. Nano- and hetero-structural effects of CNT and ITO solution on the optical and electrical effects have been studied continuously.

In this work we studied the effect of sensitizer concentration on a mobility-lifetime product μτ, on photoconductivity response time ph τph , and on drift mobility μ of the majority carriers in an organic polymer:sensitizer blend. The intensity modulated photocurrent and photo-EMF technique were used as experimental tools for this purpose. The studied material consists of a mixture of the novel non-conjugated main chain hole-transporting polymer PFO6:PDA (Poly(N,N'-bis(4-hexyloxyphenyl)-N'-(4-(9-phenyl-9H-fluoren-9-yl)phenyl)phenylen-1,4- diamine) sensitized with the highly soluble C60 derivative PCBM (phenyl-C61-butyric acid methyl ester) in the range from Z = 1 to 40 wt.-%. It was experimentally observed that (1) at the increasing sensitizer concentration the overall photoconductivity increases; (2) the majority carrier type switches from holes to electrons at approximately 2:1 polymer:sensitizer ratio; (3) the holes response time becomes shorter at the decreasing polymer fraction, while the electrons lifetime is only slightly dependent on sensitizer concentration; (4) the hole mobility-lifetime product decreases at the decreasing concentration of hole transporting component (polymer), while the electrons mobility-lifetime product increases at the increasing concentration of the electron transporting component (sensitizer); (5) the same is true for the carriers mobilities.

In the recent development of the studies in iron-based superconductors, high-pressure experiments have been played an important role. Large enhancement of Tc with applying pressure and pressure-induced superconductivity were reported in LaFeAsO1-xFx. In this work, electrical, magnetic and structural measurements on 1111 type Ca(Fe1-xCox)AsF and 11 type Fe(Se1-xTex)0.92 under high pressure have been performed. For Ca(Fe1-xCox)AsF, the substitution of Co suppressed the magnetic and structural transitions and raised superconductivity. Pressure-induced superconductivity was observed for x = 0.0 and 0.05. The highest Tc was obtained in parent compound under high pressure, in contrast to LaFeAsO1-xFx. These results suggest that the substitution of Co increases carrier concentration and induces disorder in the FeAs superconducting layer. For FeTe0.92, pressure-induced superconductivity was not detected under high pressure up to 19 GPa, although the resistive anomaly due to the structural and magnetic phase transition was suppressed by applying pressure.