CuFe-Hydrotalcite-Like Compounds (CuFe-HTLcs) were synthesized by coprecipitation with Cu(NO3)2·6H2O, Fe(NO3)3·9H2O, NaOH and Na2CO3 solution. The sample with Cu2+ / Fe3+ = 2 was of the highest crystalline characterized by XRD and particle size distribution. The synthesis of propylene carbonate from 1,2-propanediol (PG) and urea was performed to evaluate the catalytic activities of the CuFe-HTLcs. The effects of reaction time, temperature, dosage of catalyst on the synthesis of propylene carbonate were fully discussed. The optimal reaction conditions were determined by using orthogonal test design: reaction temperature 170 °C, dosage of catalyst 0.2 g, and molar ratio of PG to urea 2:1, reaction time 3 h. Under the optimal conditions, the conversion of urea nearly reached 100 %, and the selectivity of propylene carbonate was up to 90.4%.

A novel light trapping technique for solar cells is based on light scattering by metal nanoparticles through excitation of localized surface plasmons. We investigated the effect of metal nanoparticles embedded inside the absorber layer of amorphous silicon solar cells on the cell performance. The position of the particles inside the absorber layer was varied. Transmission electron microscopy images of the cell devices showed well defined silver nanoparticles, indicating that they survive the embedding procedure. The optical absorption of samples where the silver nanoparticles were embedded in thin amorphous silicon layer showed an enhancement peak around the plasmon resonance of 800 nm. The embedded particles significantly reduce the performance of the fabricated devices. We attribute this to the recombination of photogenerated charge carriers in the absorber layer induced by the presence of the silver nanoparticles. Finally we demonstrate that the fabricated solar cells exhibit tandem-like behavior where the silver nanoparticles separate the absorber layer into a top and bottom part.

The influence of the type of alumina used as catalyst support on the evolution, activity, and lifetime of the catalyst during water-assisted CVD growth (or ‘supergrowth') of single-walled carbon nanotube (SWNT) carpets has been studied. The catalyst consisted of a thin Fe film supported on alumina films deposited by different methods: atomic layer deposition (ALD), e-beam, and magnetron sputtering. In order to fully understand the influence of the type of alumina on SWNT carpet growth, crystalline alumina (c-cut sapphire) and annealed alumina deposited by e-beam were also used as catalyst supports. The activity and lifetime of Fe catalyst during SWNT carpet growth showed a strong dependence on the type of alumina used as support. Fe supported on sputtered alumina (sputtered/Fe) showed the highest catalytic activity and lifetime, which was closely followed by e-beam/Fe while Fe supported on sapphire (sapphire/Fe) showed the least catalytic activity and lifetime. AFM, XPS depth profile, variable angle spectroscopic ellipsometry (VASE) studies revealed that the catalyst evolution and the porosity of the different alumina supports correlate with the lifetime and activity of the catalysts.

A novel material design was developed by functionalizing a biocompatible hydrogel material with organic boundary lubricants. Polyvinyl alcohol was functionalized with varying molar ratios of 0.2, 0.5, and 1.0 moles of lauroyl chloride. Tribological and mechanical characterization was performed by means of nanofriction testing and nanoindentation to determine the influence of the hydrocarbon chains on the friction coefficient and elastic modulus of the hydrogels. It was found that fusing of the lubricant to the polymer material has a positive effect on the surface friction properties, yet an unfavorable effect on stiffness properties of the gel due to the processing method.

Recently, more studies have been conducted in chemical and biological applications using microfluidic or nanofluidic devices.1 Polymer-based materials have been newly developed in this field due to the great needs of easy processing, cost-effectiveness and clarity for the material. However, it is still challenging to control of the surface properties of these devices on demand. Especially, for biological analysis or detection, micro-fluidics should handle aqueous samples but, most of the current materials in use for micro-fluidic devices are relatively hydrophobic (such as PDMS, PMMA and cyclo-olefin-co polymer, etc). Therefore, they usually need an extra assistance rather than a capillary force to flow the aqueous samples. In this paper, we utilized layer-by-layer deposition of polymer to modify the surface of the micro-channel of the device in order to control surface properties of the micro-channel. We have been studied polyelectrolyte multilayer(PEM) coatings to control surface wettability of the open structures and found various hydrophilic films. Here we demonstrate polyelectrolyte multilayer film as an effective coating for inner surface of micro-fluidic devices to lowering the water contact angle, so that the aqueous fluid will travel smoothly with the channels. Compared to the other surface treatment method such as base cleaning or plasma irradiation, the PEM coating exhibit highly sustained water wettability. Polyelectrolytes used for this study are weak polyelectrolytes including biodegradable polymer such as poly(hyaluronic acid) (HA) for future biological applications.

4H SiC is a promising material because of its mechanical, electrical, and physical properties. However, SiC material defects have had a rate limiting effect on the widespread adoption of SiC. Micropipes, basal plane dislocations (BPD), elementary screw dislocations (SDD) and threading edge dislocations (TED) have all been identified as limiting to device operation and/or performance. An ideal PVT strategy for manufacturing SiC crystals would be capable of driving defects out the crystal via a combination of thermal field control and defect dissociation pathways. In this work a PVT technology was realized which is capable of continuously improving the crystal quality. A low defect PVT process was conceived and optimized using iterative experiment and simulation methods. During the maturation of the process it was observed that the crystal defect density repeatedly decreased relative to the seed crystal, as evaluated by x-ray topography, x-ray diffraction, and molten salt etching. The process improvements were leveraged successfully to achieve 4H n+ SiC wafers at 76-100 mm diameter with MPD <1 cm-2, SDD <500 cm-2, and BPD <500 cm-2. This paper will illustrate the defect reduction pathways leading to state of the art defect density 4H SiC crystals and the impact of the improved crystal on epitaxy defects and simple device experiments.

To identify the various oxalates and oxalato-nitrates likely to form during the nuclear fuel reprocessing we study crystallization of such compounds by various methods (slow diffusion, hydrothermal syntheses, in situ oxalate syntheses …), in different conditions and in presence of monovalent ions. In a first stage, lanthanides are used as surrogates of the actinides (III) radioactive elements. This communication reviews various lanthanides (III) compounds obtained by crystallization from nitric acid solution containing hydrazinium ions. Diethyl oxalate was used as a precursor for oxalate ions. A careful adjustment of the experimental conditions allowed us to synthesize single crystals of nitrates, oxalato-nitrates and oxalates with various ligand/Ln(III) ratio and containing nitrates as ligands or as counter ions. In all the compounds hydrazinium ions are present as counter ions. The crystal growth method is described and the crystal structures, determined by X-ray diffraction from single crystals, are discussed in terms of metal-oxalate frameworks.

In this work, silver nanoparticles were synthesized by two methods: polyol and chemical reduction using sodium borohydride (NaBH4). In both cases, silver nitrate was employed as starting metallic salt and Poly-vinyl pyrrolidone (PVP) as surfactant agent. The average nanoparticles size was correlated by transmission electron microscopy (TEM) and quasielastic light scattering (QELS). The experimental results indicate that the average particle sizes measured by QELS were slightly higher than those obtained directly by TEM. Therefore, this work confirms that the QELS technique can give rapid and approximate average-particle size values in comparison with those obtained through TEM direct observations.

The use of nanoparticles as carriers of photosensitizer (PS) molecules for photodynamic therapy (PDT) has attracted much interest on core-shell nanosize structures. Herein, we used a simple aqueous solution method to synthesize Fe3O4/ZnO core-shell nanoparticles. X-ray diffraction (XRD) analyses showed the presence of well defined peaks corresponding to Fe3O4 and ZnO in as-synthesized nanocrystals. Vibrating sample magnetometer (VSM) measurements showed that these nanoparticles exhibited superparamagnetic behavior of the core with no coercivity nor remanence. X-ray photoelectron spectroscopy (XPS) analyses revealed the presence of Zn1/2 and Zn3/2 species on the surface of nanocrystals. Photoluminescence measurements showed excitonic emission of ZnO co-existing with a weak and broad defect- related green emission at room temperature. The generation of singlet oxygen was monitored via the photooxidation of diphenyl-1,3-isobenzofuran (DPBF) with different light sources, followed by absorption spectroscopy at 409 nm. The capability of synthesized nanoparticles to generate singlet oxygen has also been verified.

To better understand the specific charge transfer events that occur within a dye-sensitized solar cell (DSSC), we synthesized well-defined ZnO:dye dyads. The ZnO nanocrystals were synthesized following literature procedures from zinc acetate and a hydroxide source in ethanol. The absorption onset of the ZnO nanocrystals was observed using UV-vis measurements, from which estimated nanocrystal diameters were determined. At room temperature, the synthesis yielded nanocrystals ranging in diameter from 2-4 nm. Dispersions of ZnO nanocrystals in ethanol were mixed with solutions containing 5΄΄-phenyl-3΄,4΄-di(nbutyl)-[2,2΄:5΄,2΄΄] terthiophene-5-carboxylic acid. Using FT-IR and fluorescence spectroscopy, it was verified that the dye molecules were adsorbed to the ZnO surface via their carboxylate groups while the number of dye molecules adsorbed to the surface was quantified using a combination of techniques. Adsorption isotherms were employed to probe surface coverage of the dye onto the nanocrystals to yield an adsorption equilibrium constant of 1.5 ± 0.2 x 105 M-1. The ability of ZnO nanocrystals to quench the emission of the dye by an electron transfer mechanism was observed and elucidated using ultra-fast laser spectroscopy where the time-scale for electron injection from the dye to the ZnO was determined to be 5.5 ps.

In the emerging field of low-cost printed electronics there is a lack of solvent processable conducting and semiconducting materials with highly tuned and known electronic properties. Currently the best performing conductors and semiconductors are not sufficient to produce truly printable, cost competitive organic photovoltaics (OPVs). TDA Research, Inc. (TDA) has been investigating a new class of solvent processable intrinsically conducting polymers for use as charge transport and transparent conducting layers in organic electronic devices. We have also begun the manufacture of electron-deficient semiconducting polymers that may prove to be excellent acceptors in bulk hetero-junction OPVs. This paper presents a summary of the materials characterization conducted on TDA's new electronic materials and how these may address several of the pressing issues preventing the realization of low-cost, printed solar cells and flexible electronics devices.

The Japan Atomic Energy Agency (JAEA) established the Horonobe Underground Research Laboratory (URL) Project at Horonobe, in Hokkaido, Japan to enhance reliability of nuclear waste disposal technologies to be developed in deep sedimentary environments. JAEA has undertaken a number of in-situ experiments to determine changes in the properties of the host rock and the extent of the excavation disturbed zone (EDZ) created by the excavation of underground galleries for the disposal of radioactive waste. This paper reports a seismic tomography survey (using a hammer seismic source) of the “140m Gallery” at a depth of 140m below the surface of the Horonobe URL. The observation area was 3m square on the horizontal plane along the sidewall of the 140m Gallery. The measurement was repeated with the progress of excavation of a tunnel. In this experiment, the distribution of seismic velocity in the rock around the new tunnel and its decrease as the tunnel was dug, were observed using a simple small-scale seismic tomography system. The data collected show that this system can be used to capture the EDZ around tunnels.

The photoluminescence spectra and its homogeneity for InAs quantum dots (QDs) embedded into In0.15Ga0.85As/GaAs quantum well (QW) structures with QDs grown at different temperatures (470-535°C) have been investigated at 300 K. Photoluminescence (PL) spectra along the scanning line crossed the wafers were measured at 300 K in a set of points on the QD structures under the excitation of the 804 nm line of a solid state IR laser at an excitation power density of 100 W/cm2. In QD structures with InAs QDs grown at 470°C the low integrated PL intensity, the high dispersion of QD sizes in ensemble and, as a result, the large value of FWHM (50-70meV), but the low dispersion of QD ensemble parameters along the line crossed the structures have been detected. In QD structures grown at high temperatures 490-535 °C the high integrated PL intensity, the low dispersion of QD sizes in ensemble and, as a result, less values of FWHM, but the essential dispersion of QD ensemble parameters along the line crossed the structures have been revealed. The reasons of these types of PL nonhomogeneity have been discussed.

Systematic first-principles calculations on transition metal (TM) impurities of the 3d series in Si have been performed. The equilibrium sites, migration energies, electrically-active gap levels, charge and spin states are predicted. While the properties of the isolated interstitials are experimentally well-known, much less experimental information is available about the consequences of their interactions with vacancy-like defects. We discuss here the properties of isolated interstitial Ti, Fe, and Ni, their interactions with vacancies and divacancies, the properties of the resulting substitutional impurities, and of the TM-divacancy {V-TM-V} complexes. In equilibrium, interstitial Ti, Fe, and Ni do not become substitutional, but a number of processing steps commonly used in PV manufacturing introduce highly mobile vacancies into the bulk. These vacancies strongly interact with interstitial TMs. At the substitutional site, Ti, Fe, and Ni have very different electrical properties than at the tetrahedral interstitial site. In particular, the electrical activity (and stable spin state) of Ti and Fe are greatly reduced, suggesting that the passivation by vacancies plays an unrecognized role during a variety of high-temperature processes.

First principles density functional calculations and inelastic neutron scattering measurements have been used to study the variations of the phonon density of states of PbTiO3 and SrTiO3 as a function of temperature. The phonon spectra of the quantum paraelectric SrTiO3 is found to be fundamentally distinct from those of ferroelectric PbTiO3 and BaTiO3. SrTiO3 has a large 70-90 meV phonon band-gap in both the low temperature antiferrodistortive tetragonal phase and in the high temperature cubic phase.

Key bonding changes in these perovskites lead to spectacular differences in their observed phonon density of states.

In present paper we describe some unconventional adaptions of sol-gel method. Controlled sol-gel transformation processes of metal alkoxide based systems can lead to various novel shapes of metal alkoxide materials. Formation of different structures like tubular microstructures by gel sheet rolling, nano- and microfibres by direct drawing, as well as microtubes of metal oxides and gel dispersed liquid crystal materials are described. Different aspects of sol-gel processes leading to the formation of all of these structures are thereby discussed.

ZnO nanowire (NW) has potential applications for transparent electrodes, gas sensors, nanoscale optoelectronic devices, piezoresponse force microscopy (PFM) and field effect transistors. In general, we have evaluated the electrical properties of nanowire device from I-V curves measured mainly from the bundle-like ensemble structure of ZnO, not individual ZnO NWs. Most applications require details on the electrical mobility of ZnO NWs. Recently, the electrical transport of single ZnO NWs has been studied only from several devices fabricated by electron-beam lithography. However their I-V curves categorized into three types of resistance, i.e., symmetrical, rectifying and linear shapes due to contact problems between ZnO NWs and electrodes, results in contradictory.

In this paper, we manufactured single NW device using an individual ZnO nanowire, of which the junctions were made by Pt deposition using a focused ion beam (FIB), and performed RTA processes. The single ZnO NW device consists of ZnO-Pt, ZnO-Au and Au-Pt junctions. The electrical transport of the single ZnO NW device was investigated by directly measuring the electrical resistance using nano manipulators from cross-sectioned devices. The device showed a typical Ohmic contact in I-V curves and the resistance was decrease with the RTA temperature. The CL (Cathodoluminescence) and EDS in TEM (Energy dispersive spectroscopy in transmission electron microscopy) measurements were also performed to evaluate the crystallinity (defect level) and chemical composition at the center and edge of the cross-sectioned ZnO NWs. From the results, we found that lots of defects were stored at the surface of ZnO NW and impurities at the junction were abruptly reduced. Therefore, the electrical transport of the single ZnO NW device depends strongly on the crystallinity of the ZnO NW and the C content at the Pt junction. From the electrical transport measured on the cross sectioned device, the ZnO-Au junction acted as the fastest transport path among ZnO-Pt, ZnO-Au and Au-Pt junctions in the single ZnO NW device.

In this study, the dark current-voltage characteristics of electron-only and hole-only poly(3-hexyl thiophene) (P3HT):[6,6]-phenyl C61-butyric acid methyl ester (PCBM) as a function of regioregularity (RR) and annealing time is investigated using the mobility edge (ME) model. This model is used to analyze the degradation of electron and hole mobilities as a function of annealing time for 93%-RR and 98%-RR P3HT:PCBM devices. The hole mobility is almost unchanged by the RR nature of P3HT and thermal annealing. The electron mobility, however, behaves differently after annealing. The electron mobility of 98%-RR devices, which is initially higher than that of the 93%-RR devices, experiences a steep decline with annealing. Based on ME analysis, this is due to an increase in trap states in the exponential tail caused by phase segregation of solid state blends of 98%-RR polymer and PCBM. The electron mobility of 93%-RR devices increases with annealing due to an optimization of nano-phase separated morphology.

X ray diffraction (XRD) is the common technique for texture analysis by means of pole figure (PF) measurement. PF reflects the grains orientation distribution but contains no information about grain microstructure. The reflected intensity can be affected by the extinction phenomenon that reduces the pole density (PD). The parameters of extinction are related to the crystal microstructure. The parameter of the primary extinction is connected with domain size and parameter of the secondary extinction is related to the angle of domains disorientation that depends on dislocation density in domain boundary. An original XRD method is proposed for correction of PD, considering extinction phenomenon, and separation of the extinction parameters in the case of textured aluminum. The problem is solved under some assumptions. In the present work cold rolled nickel with and without annealing at 600 °C is investigated. The validity of the proposed assumptions for Ni is evaluated in terms of the extinction length. The corrected PD in the maximum of PF and the parameters of the primary and secondary extinction are calculated using the first order reflection for Cu K α- and Co K α- radiations and the second order reflection for one of the used wavelengths. Both in cold rolled sample without annealing and in the annealed sample the primary and secondary extinctions are present simultaneously. According to the obtained parameters of extinction the microstructure of textured nickel is evaluated and their modification at the annealing process is demonstrated.

Carbon nanotubes are attractive candidates for electron field-emitters due to their high aspect ratio, mechanical stability, and electrical conductivity. It has previously been shown that an electron beam hitting the tip of a carbon nanotube biased near the threshold of field-emission can stimulate the emission of a large number of electrons from the nanotube tip. Here we report on similar experiments on arrays of free-standing multi-walled carbon nanotubes (nanotube forests) interacting with a scanning electron microscope's primary beam. Electron gains of up to 19,000 were obtained. This can enable applications such as electron detection and multiplication, and vacuum transistors.