We investigate the electrical transport in quasi-1D piezo-semiconductive NWs under purely vertical compressive or tensile strains. For simplicity, we exclusively consider the additional band bending originated by the piezoelectric charges assumed to be distributed, with a constant volumic density, within a maximum distance δpiezo 003F from the metal-to-NW junction. Our calculations demonstrate that the carrier concentration, the energy conduction band profile and the I-V characteristics significantly depend on δpiezo 003F . We therefore propose that I-V measurements can allow to obtain information on δpiezo 003F in strained piezo-semiconductors.

Papers in the Appendix were published in electronic format as Volume 1534

A new technology to size nanoparticles in liquids is presented. The technique is based on aerosol technology coupled to a nanoparticle nebulizer. This allows number concentration measurements in the size range ca. 5 to 500 nm with high peak resolution.

Degradation of the catalyst and catalyst support is an essential limitation of polymer electrolyte membrane (PEM) fuel cells containing commercial platinum on carbon catalysts. Catalysts based on platinum nanoparticles coated onto nanostructured TiO2 materials are presently investigated as a more stable and equally cost effective alternative. Reported here is the synthesis of two different Pt/Nb0.1Ti0.9O2 catalysts that were prepared by chemical reduction of H2PtCl6 with either sodium borohydride in ethanolic surfactant solution or ethylene glycol. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy confirmed the deposition of Pt nanoparticles on the surface of the nanofibers and revealed average sizes of 5.4 nm and 7.6 nm for reduction with ethylene glycol and sodium borohydride, respectively. The formation of smaller sized Pt nanoparticles in ethylene glycol is reasoned with the passivation of the nanoparticle surface by glycolic anions. Cyclic voltammetry measurements confirmed a higher electrochemical specific surface area (ESCA) of about 5.45 m2/gPt for the catalyst with smaller nanoparticles while the other catalyst reached only 4.96m2/gPt. Both catalysts retain about 60% of their electrochemically active surface area after 1000 voltammetric cycles in the range of 0.03 to 1.4 V vs. RHE. This relatively high value of activity retention is explained with a strong interaction between Pt nanoparticles and Nb0.1Ti0.9O2 support.

CdTe is well known as an excellent photovoltaic material for high efficiency solar cell applications because it has a direct band-gap, low fabrication cost and high optical absorption coefficient. However, the nonradiative recombination and low average minority carrier lifetime caused by the defects in CdTe solar cells limit its efficiency. So far, grain boundaries (GB) have been considered to be the major origin of the nonradiative recombination. However, we show that CdTe grains contain many dislocations that could limit device efficiency. Scanning transmission electron microscopy (STEM) was used to determine the atomic structure of intrinsic and extrinsic stacking faults and their terminating partial dislocation cores. Z-contrast images are sensitive to atomic number and are able to distinguish Cd and Te atomic columns. Unpaired Cd and Te atomic columns were found to form the partial dislocation cores, suggesting the presence of dangling bonds. These defects are likely to be electrically active, and may be the origin of the low minority carrier lifetime.

Synergistic compositions of detonation nanodiamond (ND) particles in the form of 100nm aggregates in combination with molybdenum dialkyldithiophosphate were used as additives to 10W40 oils. Ring-on-disk tribological tests were performed under high load conditions using friction pairs with different hardnesses, namely normalized-normalized (“soft/soft”) and normalized-quenched (“soft/hard”) steel samples. For the “soft/hard” steel friction pair NDs provide significant reduction in both the coefficient of friction and wear as well as demonstrate polishing. For the “soft/soft” steel friction pair, however, no difference in the coefficients of friction was observed when the base oil was used with or without ND. In the test with oil containing the ND additive, the wear scar in the disk was wider, but more shallow, than in the test with pure oil. Current tests indicate that the significance of the reduction of friction and wear of the sliding surfaces in the presence of the ND additive in oil strongly depends on the hardness of the friction surfaces and most probably is connected with ND polishing effect.

Papers in the Appendix were published in electronic format as Volume 1534

Commercially available antimony tin oxide (ATO) nanoparticles were dispersed in water using tetramethylammonium hydroxide (TMAH) as a dispersing agent and deposited onto glass substrates by spin coating. Films of one to five layers were made. These thin films were characterized using impedance spectroscopy and ultraviolet-visible spectroscopy to obtain their sheet resistances and optical transmittance, respectively. The films displayed sheet resistances around 105-106 kΩ/☐ and optical transmittance in the near infrared to near ultraviolet range above 95%. Films were then made using a higher concentration ATO solution and found to achieve sheet resistances on the order of 102 kΩ/☐ but had decreased transmittance as low as 65% at some wavelengths. Impedance measurements, along with optical micrographs, were taken at different locations on the films. These experiments demonstrated that films of more than one layer showed greater uniformity. Additional sets of films were also produced with varying substrate preparation and dispersion deposition parameters. Aside from dispersion concentration, high humidity during film measurement was found to be the most crucial parameter for achieving low sheet resistances.

Dielectric capacitors for energy storage are of great importance in modern electronics and electric systems. It is a challenge to realize the high energy density while maintain the low dielectric loss. We investigated an ultra high breakdown electric field of 1.1 GV/m, which is approaching the intrinsic breakdown, in aromatic polythiourea, a new dielectric material that serves a high energy density of 23 J/cm3 as well as high charge-discharge efficiency above 90%. The molecular structure and film surface morphology were also studied, it was proved a polar amorphous phase and glass state material could significantly suppress the high field conduction to several orders smaller compared with regular polymer dielectric materials, which are usually semi-crystalline and in rubber phase.

High purity bulk graphite is applicable in many capacities in the nuclear industry. The thermal conductivity of graphite has been found to vary as a function of how its morphology changes on the nanoscale, and the type and number of defects present. We compute thermal conductivities at the nanolevel using large scale classical molecular dynamics simulations and by employing the Green-Kubo method in a set of in silico experiments geared towards understanding the impact of defects in the thermal conductivity of graphite. We present the results obtained for systems with 1– 3 vacancies, and compile a summary of some of the methods applied and difficulties encountered.

An amorphous silica film has been coated on a fused silica glass and KH2PO4 [KDP] crystal by using the photo oxidization of Dimethy-siloxane silicone [DMSS] oil by using a xenon [Xe2] excimer lamp at room temperature. The DMSS oil [-O-Si[CH3]2-O-]n was spin-coated on a fused silica glass to make a thin film, and the Xe2 lamp light was vertically irradiated in the presence of oxygen. Thus, the organic oil was changed into inorganic glass. In order to investigate the photochemical reaction process, the fluorescence intensity was measured by spectrometer at actual time and the new method to form a transparent, photo-oxidized thin film efficiently has been established. The interferometer analysis was conducted to investigate the strain of the coating samples. It became clear that the no strain were caused by vitrification of the silicone oil on the fused silica galass with Xe2 lamp irradiation.

Traditional assembly line manufacturing is speculative, costly and environmentally unsustainable. It is speculative because it commits substantial resources—energy, materials, shipping, handling, stocking and displaying—without a guaranteed sale. It is costly because each of these resources—material, process, people and place—involves expense not encountered when a product is manufactured at the time of sale. It is environmentally unsustainable because, no matter how much recycling is done, not using the resources unless actually needed is always a better path. Three-dimensional printing is currently of great commercial interest as it can be employed to manufacture parts on-demand economically and without the significant cost & environmental downsides, i.e. inventory and waste, associated with traditional manufacturing processes. Herein, we describe the formulation of a novel water-based material which can be used in a traditional 3D printer extrusion process to create optically transparent glass-based objects. Such objects have a wide range of applications including, but not wholly limited to: security printing using color & coating effects, protective films and coatings, electronic codes readable by smartphones, tablets or touch screens. Additional all glass objects traditionally manufactured by the so called kiln glass method can be generated by this type of 3D printing making it interesting for the high end market of art objects.

The application of micro-fourier transform infrared (FTIR) mapping analysis to thermoelectric materials towards identification of doping inhomogeneities is described. Micro-FTIR, in conjunction with fitting, is used as analytical tool for probing carrier content gradients. The plasmon frequency ω P 2 was studied as potential effective probe for carrier inhomogeneity and consequently doping differentiation based on its dependence of the carrier concentration. The method was applied to PbTe-, PbSe- and Mg2Si- based thermoelectric materials.

We present a Scanning Probe Microscopy study of doping and sensing properties of reduced graphene oxide (rGO)-based nanosensors. rGO devices are created by dielectrophoretic assembly of rGO platelets onto interdigitated electrode arrays, which are lithographically pre-patterned on top of SiO2/Si wafers. The availability of several types of oxygen functional groups allows rGO to interact with a wide range of organic dopants, including methanol, ethanol, acetone, and ammonia. We perform sensitive Scanning Kelvin Probe Microscopy (SKPM) measurements on patterned rGO electronic circuits and show that the local electrical potential and charge distribution are significantly changed when the device is exposed to organic dopants. We also demonstrate that SKPM experiments allow us to quantify the amount of charge transferred to the sensor during chemical doping, and to spatially resolve the active sites of the sensor where the doping process takes place.

CdS:Li nanoparticles were grown by the thermolysis method using a surfactant to control the nanoparticles growth and the passivity of the dangling bonds. The effect of the Li incorporation on the optical and structural properties of the CdS nanoparticles was studied by means of the optical transmission, photoluminescence, X-ray diffraction and HR-SEM&TEM techniques. The optical energy band gap lies in the interval from 2.7 to 3.6 eV. The photoluminescence spectra present a band with peak at 465 nm, which is indicative of the quantum confinement. The energy peak position (465 nm) is blue-shifted respect to the bulk material (512 nm). Then, one can infer that the energy band gap and the peak intensity vary according to the nominal lithium concentration in the growth solution. An average crystallite size of about 5 nm was estimated by the Brus equation and the Debye-Scherrer formula, and confirm by HR-SEM&TEM measurements.

For the purpose of development of highly energy-efficient light sources, one needs to design highly efficient green, red and yellow phosphors, which are able to absorb excitation energy and generate emissions. In this contribution, we present our results on producing some efficient phosphors with improved luminescence properties. The effects of zinc on the zinc-doped CaTiO3:Eu3+ phosphors have been investigated by varying the zinc concentrations. X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM) characterizations were studies for their structural and morphological analysis. The variation of zinc concentration influences the crystallinity and morphology of the phosphors. The luminescence spectra of (Zn,Ca)TiO3: Eu3+ have been measured. Eu3+: (Zn,Ca)TiO3 have shown five emission transitions of 5D0→7F 0,1,2,3 & 4 located at 580 nm,593nm 615 nm,655 and 704 respectively with excitation at λexci=398nm (7F0→5L6). Moreover, the emitting phosphor developed in this study can be very effectively excited at the wavelengths of 398 nm. The (Zn, Ca)TiO3:Eu3+ can be used as a complementary phosphor in there red region for the white LEDs.

We have performed an analysis on three hydrogenated nanocrystalline silicon (nc-Si:H) based solar cells. In order to determine the impact that impurities play in shaping the material properties, the XRD and Raman spectra corresponding to all three samples were measured. The XRD results, which displayed a number of crystalline silicon-based peaks, were used in order to approximate the mean crystallite sizes through Scherrer's equation. Through a peak decomposition process, the Raman results were used to estimate the corresponding crystalline volume fraction. It was noted that small crystallite sizes appear to favor larger crystalline volume fractions. This dependence seems to be related to the oxygen impurity concentration level within the intrinsic nc-Si:H layers.

HoxEr1-xN (x=0.25, 0.5, 0.75) samples were synthesized by nitriding of HoxEr1-x alloy bars and their thermal conductivity κ were measured. The measured κ values were comparable to those of stainless steel and Er3Ni. Ho0.5Er0.5N showed the highest κ of the present three samples. The thermal diffusivity calculated from the κ and the specific heat indicates that Ho0.5Er0.5N is a very promising regenerator material for the cryocoolers. The electrical resistivity ρ was also measured as a function of temperature.

The photovoltaic materials in solar cells take multiple tasks including absorbing lights, separating the light-induced electron-hole pairs, and consequently transport charges to the corresponding metallic electrodes. These tasks, however, are often mutually conflicting. In particular, a thick PV layer is desired to absorb enough light for creating sufficient light-induced charges, while a thin PV layer is also desired to shorten the charge transport path length insider the PV layer in order to suppress recombination. Using dye-sensitized solar cells as an exploratory platform, this dilemma is mitigated using a non-traditional 3-dimensional (3-D) highly doped fluorinated SnO2 (FTO, core)-TiO2(shell) nanostructured photoanodes. The FTO core serves as conductive core for low-resistance and drift-assisted electron extraction. The thin, conformal and low-doped TiO2 shell layer is coated by atomic layer deposition, which provides a large area for anchoring dyes and maintains a large resistance against recombination.