The various perovskite ceramic electrolytic membranes, (Ba,Sr)(Zr,Ce,Nb,In,Sn)O3 modified by incorporation of Ln/RE elements, are widely investigated due to their high industrial potential for H2 production and CO2 conversion. One of the most important criteria to classify such ceramic as a good membrane is its high mechanical and chemical stability over thousands hours in severe operating conditions: high temperature and (high water) vapour pressure cycling. It is well known that the Ba- and Sr-based materials can easily form the mixed carbonates, hydroxides, hydrates, hydroxycarbonates, … The presence of undesirable phases, even limited to traces, on the ceramic surface, and/or at the grain boundary, may lead directly to the premature degradation. Since such mixed, hydrated, poorly crystallized phases cannot be detected by diffraction experiments, we have performed thermogravimetric analysis as well as IR and Raman spectroscopic study. The comparison of vibrational and TGA signatures characteristic of complex secondary phases i.e. (Sr/ Ba)(OH)x(CO3)y, nH2O and of proton conducting perovskite reveals that the ignorance of a second phase presence can lead to wrong conclusion concerning the bulk proton nature and understanding of associated conductivity mechanisms.

Oxygen reduction in SOFC cathodes has long been the rate determining step in SOFC operations, mixed ionic-electronic conductors (MIECs) and/or forming composite between cathode and electrolyte materials have been common strategies in order to aid the cathode kinetics. We demonstrate here a viable synthesis route to impregnate mesopores with high loading of platinum towards a mesoscale bicontinuous material that composed of channels of a fast ionic conductor, i.e. gadolinium doped ceria (GDC) intertwined with channels of a good electronic conductor, i.e. Pt. This highly structural composite material holds the promise of a high performing cathode in SOFC.

Technetium-99 is considered as one of the most dangerous nuclear environmental pollutants due to its long half-life (210,000 y.) and high mobility in aqueous solutions under oxidizing conditions. Development of sorbents, which are capable of irreversible uptake of Tc and further direct conversion into durable ceramic waste forms, is an important field of research. Titanate ceramic doped with up to 10 wt. % Tc was successfully synthesized using Layered Hydrazinium Titanate, LHT-9 (PCT/EP2010/001864) as starting precursor. LHT-9 is a new advanced compound of general formula (N2H5)1/2Ti1.87O4 xH2O containing 6-7 wt. % of hydrazine chemically incorporated into a TiO2-based matrix. It was demonstrated that LHT-9 (5g/l) can reductively adsorb up to 90.2 wt. % of Tc from aqueous solutions containing 0.5g Tc/l. The obtained adsorption products can be easily converted into stable titanate ceramic by one-step sintering in argon atmosphere at 1200°C. Phase and chemical composition of synthesized Tc-doped ceramic are discussed.

Silicon and Germanium nanowires (NWs) have shown a strong ability to enhance both the absorption and scattering of light. Tailoring the optical properties of Si or Ge NWs can be obtained by adjusting the nanowire diameter. Another parameter that can be used is the chemical composition of silicon-germanium (Si1-xGex-NWs) alloys. In this work, we perform a numerical study on the optical properties of single Si1-xGex-NWs based on the Lorenz-Mie theory. The effects of Ge composition, light polarization and angle of incidence on the nanowire optical properties are investigated.

We present a calculation of vibrational frequencies of formate on the AuPt(111) surface alloy including full anharmonicity and coupling of all six intramolecular degrees of freedom. This species is a key intermediate in methanol oxidation on this material. We use a modified version of the method of Manzhos and Carrington to compute the spectrum directly from a small number (<10,000) of DFT single-point energies, bypassing the construction of a potential energy surface. This is the first such calculation for a 4-atomic species at a surface. The spectrum is obtained using rectangular collocation and a small basis set of parameterized Hermite functions. The achievable accuracy of the order of several cm-1 corresponds to the typical experimental resolution. Using normal coordinates makes the equations simple and general and easily applicable to other systems. This calculation is doable on a PC. We predict that anharmonicity and coupling lower the fundamental frequencies by dozens of cm-1, which could affect species assignment.

Microcontact printing is a versatile patterning technique, but is often limited by deformation of the stamp pattern. This paper examines the sensitivity of stamp pressure distributions to variations in displacement when the microcontact printing stamp is mounted on a rigid roll. To this end, we examine analytic and numeric solutions to the contact problem and verify our models with experimental data. Using these results, we provide insight to process limits imposed by dimensional errors in the printing system.

This paper reports on light filtering devices based on a-SiC:H tandem pi´n/pin heterostructures. The spectral sensitivity is analyzed. Steady state optical bias with different wavelengths, are applied from each front and back sides and the photocurrent is measured. Results show that it is possible to control the sensitivity of the device and to tune a specific wavelength range by combining radiations with complementary light penetration depths. The transfer characteristics effects due to changes in the front and back optical bias wavelength are discussed.

Input red, green and blue pulsed communication channels are transmitted together, each one in a specific bit sequence and the multiplex signal is analyzed. By superimposing appropriate background and depending on the channel/background wavelength combinations, the device behaves as a long- or a short- pass filter, producing signal attenuation, or as an amplifier, producing signal gain. A physical model is presented to support the filter properties of the device.

Ionic liquids (ILs) are receiving a great deal of attention as synthetic and dispersion media for colloidal systems, as well as alternatives to organic solvents and electrolyte solutions. Colloidal stability is an essential factor for determining the properties and performance of colloidal systems combined with ILs. The remarkable properties of ILs primarily originate from their highly ionic nature. While such high ionic strength often causes colloidal aggregation in aqueous and organic dispersions, certain colloidal particles can be well dispersed in ILs without any stabilizers. First, we will discuss the colloidal stability of bare and polymer-grafted silica nanoparticles and the surface force between silica substrates in ILs. Three different repulsions between colloidal particles—electrostatic, steric, and solvation forces—will be highlighted. A possible interpretation of the stabilization mechanism in ILs, both in the presence and in the absence of stabilizers, will be proposed. Next, we will provide an overview of our recent studies on colloidal soft materials with ILs. On the basis of dispersed states of the silica colloids, two different soft materials, colloidal gel and colloidal glass in ILs, were fabricated. Their functional properties (such as ionic transport, rheological properties, and optical properties) and the microstructure of the colloidal materials will also be presented.

We report the microstructural features of GdBa2Cu3O7-δ (GdBCO) coated conductors (CCs) on LaMnO3 (LMO)-buffered IBAD MgO template, produced by the Reactive Co-Evaporation Deposition & Reaction (RCE-DR) process. Analysis results by X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that a lot of elongated round second phase particles of 70-150nm size within the GdBCO matrix were the Gd2O3 phase, a small amount of Cu-O phase were also trapped in the GdBCO matrix, and a thick layer of Cu-excessive Ba-Cu-O phase was found on the top surface of the GdBCO film, suggesting that the GdBCO film might be grown from Gd2O3 and liquid phase by a peritectic recombination. While both the GdBCO film and some Gd2O3 particles grown on the LMO-buffer layer were biaxially textured, the Gd2O3 particles fully trapped in the GdBCO matrix were randomly oriented. The Gd2O3 particles located at the interface between the GdBCO and LMO buffer layer exhibited the following crystallographic orientation relationship: LMO [010] // GdBCO [010] // Gd2O3 [110]; LMO [001] // GdBCO [001] // Gd2O3 [001].

The focus of this research is on network formation and electrical conduction in carbon nanotube polydimethylsiloxane nanocomposites. Carbon nanotube network formation prior to and during polymerization was monitored by means of simultaneous electrical and rheological characterization. Processing induced network formation at filler concentrations below statistical percolation was observed, and both the electrical resistivity and the voltage dependence of the sample resistance were found to increase with the degree of polymerization, indicating carbon nanotube separation during polymer cure. Electron tunnelling through insulating polymer layers was identified as the main conduction mechanism. Information about the final network structure and further details about electrical conduction were obtained from the piezoresistive response of the material. Electron tunnelling was found to be dominant at filler concentrations close to the percolation threshold. With increasing filler concentration a densification of the carbon nanotube network was observed, and the resistance behaviour at high filler content was better described by the behaviour of a parallel circuit.

Shockley-Queisser detailed balance theory predicts that under one sun a semiconductor with its bandgap in the range of 1.0 – 1.6 eV can potentially achieve an energy conversion efficiency > 30%. Therefore, the conversional wisdom would suggest looking for a semiconductor with a bandgap in this range for a single junction solar cell. Here we explore an alternative way of selecting the absorber material for PV, which allows using semiconductors with much larger bandgaps, in conjunction with new device architecture. Specifically, our device is based on an array of core-shell semiconductor nanowires, such as ZnO-ZnSe, where the two components exhibit type II band alignment. Our approach relies on the most basic property of a type II heterojunction, i.e., the staggered band alignment, that provides the function of charge separation, as in the case of dye-sensitized solar cell or (organic) bulk heterojunction solar cell. However, they differ in two important aspects: (1) the current structure is all inorganic, thus, expected to offer better chemical and photo- stability; and (2) In this approach, the interfacial transition provides an effective absorption or photo-response threshold that can be much lower than that of either component. In this work, using a ZnO-ZnSe core-shell nanowire array, we report the observation of the key signatures associated with the type II optical transition, and the demonstration of a solar cell based on the core-shell nanowire array.

Iron oxide (Fe2O3, 20-40 nm), aluminum oxide (Al2O3, 50 nm) and silicon oxide (SiO2, 20-60 nm) nanoparticles were mixed in different concentrations (1 to 5 wt %) in a magnesium oxide matrix to develop new refractory matrixes as candidates in the lining of secondary ladle metallurgy. To avoid agglomeration of nanoparticles in the magnesium oxide (MgO) matrix, it was carried out a dispersion method of nanoparticles with different dispersants. After that, the powder mixture was sintered at a temperature of 1300 and 1500 °C for 4 hours. The refractory samples obtained were studied using X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectrometer (SEM-with EDX) and also measured their density and porosity. The results showed that the samples sintered at 1500 °C with 5 wt % of Fe2O3 reached the highest density and presented the MgFe2O4 spinel-type phase. With the addition of Al2O3-nanoparticles in the MgO matrix, there were the formation of MgAl2O4 spinel phase and in the case of SiO2-nanoparticles addition it was observed the formation of Mg2SiO4 forsterite phase. It is well known that with the increase in spinel phase in the matrix, there is a significant help to retain quantities of ions of iron and nickel due to the dissolution of the slag into the refractory material extending their lining life.

A plasmonic back reflector has been fabricated for light-trapping application in thin film Si photovoltaic devices. The back reflector comprises of a 2D array of self-organized Ag NPs separated from a planar Ag mirror by a ZnO layer deposited by atomic-layer deposition. The diffuse reflectance and parasitic absorption losses can be modulated by varying the ZnO thickness. A maximum diffuse reflectance peak value of 30% at 950 nm, with a bandwidth of 400nm, is observed for ∼100 nm diameter NPs at a distance of 50 nm from the Ag mirror. Finite-difference time-domain simulations of a 100nm Ag sphere near a mirror were used to understand the experimentally observed trends in diffuse reflectance and parasitic absorption, with distance from the mirror. Particles very close to the mirror can couple to delocalized surface plasmons or exhibit Fano resonance effects, thereby increasing parasitic absorption. Particles situated away from the mirror are influenced by driving-field effects due to the interaction of incident and reflected photons, which modulate the scattering cross-section.

Its intrinsic nontoxicity makes the direct band gap InP/ZnS core/shell be one of the most promising semiconductor nanocrystals for optoelectric applications, with the advantage of tuning the optical absorption range in the desired solar spectrum region. Highly luminescent and monodisperse InP/ZnS nanocrystals were synthesized in a non-coordinating solvent under a thorough degassing process. By varying synthesis scheme, different size InP/ZnS nanocrystals were grown. For the purpose of ensuring air stability, ZnS shell was grown. This ZnS shell improves the chemical stability in terms of oxidation prevention. Measurements of absorption and emission were performed on different InP/ZnS nanocrystals with different sizes. As expected, the measurements show a red-shift as the size of the InP/ZnS nanocrystals increased.

A thin film consisting of boron, carbon, and nitrogen (BCN) was grown on a polycrystalline Ni substrate by thermal chemical vapor deposition. The local elemental composition of the BCN film was analyzed by scanning Auger electron spectroscopy. The film is elementally highly inhomogeneous and consists of domains with a typical size of 1-10 μm and irregular shapes. The domain structure is strongly related to the structure of the grains of the polycrystalline Ni film beneath the domain. A thick domain is often formed on a small Ni grain. On a large and flat Ni grain, the film thickness is relatively small, and both the boron and nitrogen contents are often below the detection limit, indicating that it is a graphene domain. Boron and nitrogen contents are highly correlated, which is consistent with formation of hexagonal boron nitride. However, unbalanced boron and nitrogen contents are observed from thick domains.

The purpose of this work is to fabricate large-scale solution processable graphene-based films from graphene oxide (GO) solution and to characterize the transport properties of these films. The graphene like film is produced by annealing of the GO film to form reduced graphene oxide (rGO) thin films. The conductive rGO thin films are useable as spacer layers in spin valves and as organic electrodes. Atomic Force Microscope (AFM) characterizations on the film thickness and morphology have been carried out and simple electrical transport studies performed on spin coated rGO thin films. We have fabricated rGO thin films ranging from few to tens of nanometers in thickness with conductivities in the order of 1-100 S/m. We also show that the morphology of the films play an important role in facilitating higher conductivities for rGO thin films.

We have successfully prepared La0.5Sr0.5MnO3nanowires using a novel hydrothermal synthesis process and studied their magnetic and magnetocaloric properties. The system exhibits an inverse magnetocaloric effect (IMCE) around 175 K indicating presence of significant AFM correlation. The MCE study reveals a clear paramagnetic (PM) to ferromagnetic (FM) transition near room temperature (T ~ 325K) which is followed by onset of AFM at lower temperatures. The development of the FM-like magnetic state at low temperature is attributed to the enhanced double exchange (DE) driven ferromagnetism in AFM state as predicted by recent theoretical studies.

The commercial viability of solar power will depend on a careful balance of reliability, efficiency, and overall cost. A systematic approach to the optimization of the latter two for the case of organic solar cells is outlined. This relies among other on the development of a detailed understanding of the charge generation process and the systematic application of analytical tools such as UV-vis, photoluminescence, lifetime measurements, and current-voltage (I-V) curves.

We have developed a QCM (Quartz Crystal Microbalance) based method for direct gravimetric determination of water adsorption on PuO2 surrogate surfaces, especially CeO2, under conditions representative of those in a typical PuO2 storage can. In this application, the method of transduction of the QCM relies upon the linear relationship between the resonant frequency of piezoelectrically active quartz crystals and the mass adsorbed on the crystal surface. The spurious effect of high temperatures on the resonant frequency of coated QCM crystals has been compensated for by modeling the temperature dependence of the frequency response of the surrogate coated-QCM crystal in the absence of water. Preliminary results indicate that water is readily adsorbed from the vapor phase into porous metal oxide structures by capillary condensation, an observation that may have important ramifications for water uptake within the packed powder beds that may obtain in PuO2 storage cans.

The theory of the interaction of elastic waves with dislocations is reviewed, as is the extent to which it has been tested by experiment. There are two essential ingredients to the wave-dislocation interaction: one is that, when a wave hits a dislocation, the latter will respond by moving in some fashion. The other is that, when a dislocation moves, it generates (“radiates”) elastic waves. For a linearly elastic solid continuum, both phenomena can be described by equations that are linear outside the dislocation core. One is a linear elastic wave equation with a right-hand-side term that is localized at the dislocation position. The other is a linear equation for the vibrations of a string (that is coincident with the dislocation), with an external loading provided by the wave. This provides the basic mechanism for the scattering of elastic waves by dislocations, and it can be worked out in considerable detail for pinned dislocation segments and prismatic dislocation loops in infinite media, as well as for the scattering of surface (Rayleigh) elastic waves by subsurface dislocation segments.

The results for the scattering by a single dislocation can be used as input in a multiple scattering formalism to study the properties of a coherent wave propagating in a solid with many dislocations present. Expressions for the effective velocity of propagation, and for the disorder-induced (as distinct from the internal losses) attenuation can be found. They test successfully with Resonant Ultrasound Spectroscopy (RUS) experimental measurements.

Open problems, possible further applications and current efforts are discussed.