ZnO doped with transition metal (TM) thin films were grown by pulsed laser deposition. XRD pattern reveals that all the ZnTMO films have c-axis orientation normal to the substrate. The reciprocal space mapping shows that the crystallinity of ZnTMO film deteriorates at higher doping of TM. All the TM doped ZnO films have transmittance greater than 75% in the visible region. The band gap of the ZnTMO thin films shows red shift on doping with Ni and Cu where as blue shift is observed for Co and Mn which increases with TM concentration. The copper doped ZnO thin film shows green PL emission at 542 nm along with the band edge emission at 385 nm. But other TM doping shows only band edge emission (385nm) and its intensity decreases at higher doping percentage. The presence of non-polar E2 high and E2 lowRaman modes in thin films indicates that ‘TM’ doping do not alter the wurtzite structure of ZnO. The magnetic studies of the TM doped ZnO shows room temperature ferromagnetism

Uncertainty about future energy and water supplies suggests a pressing need to develop efficient technologies for water desalination. Capacitive deionization (CDI), a method that captures ions in the electrical double layer (EDL) of an electrochemical capacitor, is a promising technology that can potentially fulfill those requirements. Similar to supercapacitors, ideal CDI electrodes should have a large electrolyte-accessible specific surface area available for ion adsorption with rapid charging/discharging characteristics. Unlike supercapacitors, CDI electrodes are required to operate in aqueous electrolytes with low ionic concentrations in a non-linear charging regime. To explore this practically and theoretically important regime, we developed robust, electrochemically-compatible carbon nanotube (CNT) carpet electrodes that posses a well-defined and uniform pore structure that is more readily analyzed in comparison to the random and multi-scale pore structure of typical carbon electrodes. The fabricated electrodes were characterized using cyclic voltammetry and potentiostatic charging in aqueous NaCl solutions (n o = 20 - 90 mM) using a three electrode setup. Examination of the CV and potentiostatically-measured capacitances were consistent with EDL behavior dictated by the Stern layer. However, some deviations from the expected behavior were observed with increasing salt concentration during potentiostatic testing.

The unique properties of carbon nanotubes (CNTs), such as high strength and stiffness, extremely large specific surface area, low density and high electrical and thermal conductivities, open up opportunities for a wide range of applications. This has led to widespread research on the synthesis of multiscale CNT-based polymeric composites transferring the properties from nanoscale to macroscale. Currently known conventional methods for producing CNT composites rely on dispersing short nanotubes in polymer matrices or infiltrating CNT “buckypaper” with resins. Unlike conventional methods, in this work, super-aligned long CNTs were directly drawn from the vertically aligned CNT arrays and assembled into high volume fraction (~60 vol%) composites. These critical structural features allowed the CNT composites to reach tensile strengths over 1.8 GPa and electrical conductivity ~700-800 S/cm. Thermoplastic and thermosetting polymers were utilized for the fabrication and the results were compared. Our observation suggests that the strengthening and conducting mechanism is derived from the synergistic effect of high degree of CNT alignment, long CNT length, high volume fraction and uniform distribution of CNTs in the polymer matrix produced by spray-winding.

Models of radiation growth proposed to date are all based on the assumption that the primary damage is produced by neutron irradiation in the form of single defects. These models do not account for the features of the cascade damage: intra-cascade clustering of self‑interstitial atoms (SIAs) and their one‑dimensional diffusion. During the last twenty years, a ‘Production Bias Model’ has been developed, which shows that the damage accumulation in cubic metals depends crucially on the cascade properties. The cascades in hcp zirconium are similar to those in cubic crystals; hence the model can provide a realistic framework for the hcp metals as well. In this work we present such a model in application to low-temperature (below 300°C) radiation growth.

In efforts to achieve higher efficiency of thin film Si solar cell, light trapping is one of the most important strategies in designing the cell structure. From the past studies, it is well known that TCO with a higher haze can exhibit better light trapping characteristics for a superstrate type thin film Si solar cell, while such TCO could give lower Voc and FF values caused by steep valleys in the texture of TCO. Furthermore, TCO with too high haze in a longer wavelength region could make back reflectance at the Ag rear electrode/reflector lower due to plasmonic effect on rough surface of Ag and thus reduces the efficiency of light trapping. In order to solve this contradictory behavior of light trapping in a conventional thin film Si solar cell, we have newly developed a glass-laminated module of thin film Si solar cell which has enhanced light trapping without deteriorating Voc nor high reflectance of Ag rear reflector.

Water-soluble Fe3O4@ZnO composite nanoparticles (NPs) were synthesized using a polyol route. The effects of the addition of the ZnO phase were evaluated by varying the Zn/Fe molar ratio in the 0.25-1.00 range as a function of the reaction time. X-ray diffractometry confirmed the formation of the magnetite and ZnO phases and suggested the possible formation of a composite structure. Also, using this method, pure magnetite and ZnO NPs were synthesized. The average crystallite sizes were estimated to 6.3 ± 0.3 nm and 8.6 ± 0.6 nm for magnetite and ZnO NPs, respectively. The samples were examined using transmission electron microscopy. Fourier transform infrared spectra indicated the presence of adsorbed species onto the solids surface, which may explain the good stability of the materials in water. Photoluminescence measurements at room temperature for pure ZnO nanoparticles exhibited the characteristic excitonic emission around 395 nm. Vibrating Sample Magnetometer measurements at room temperature evidenced the superparamagnetic behavior of magnetite nanocrystals, with a saturation magnetization of 60emu/g. The maximum magnetization ranged from 28 to 54emu/g for the composite NPs. Mössbauer spectroscopy measurements at room temperature showed evidence of evolving Fe-sites associated to superparamagnetic particles, as reflected on the coexistence of prominent doublet peaks and very weak sextet peaks.

The present study was carried out to evaluate the microstructures and mechanical properties of severely deformed Ni-30Cr alloy. Cross-roll rolling (CRR) as severe plastic deformation (SPD) process was introduced and Ni-30Cr alloy sheets were cold rolled to a 90% thickness reduction and subsequently annealed at 700 °C for 30 min so as to obtain the recrystallized microstructure. For the analysis of grain boundary character distributions (GBCDs), electron back-scattered diffraction (EBSD) technique was introduced. CRR on Ni-30Cr alloy was effective to enhance the grain refinement through heat treatment; consequently, average grain size was significantly reduced from 33 μm in initial material to 0.6 μm in CRR processed material. This grain refinement directly affected the mechanical properties improvement, in which yield and tensile strengths were significantly increased than those of initial material. In this study, we systematically discussed the grain refinement, accompanying with increase in mechanical properties, in terms of the effective strain imposed by CRR, comparing with conventional rolling (CR).

In this work we study the effect of different reducing agent (chitosan, starch and sugars) on to synthesis of silver (AgNPs) and gold (AuNPs) nanoparticles by reduction of silver nitrate (AgNO3) and chloroauric acid (HAuCl4), respectively. The plasmon absorption peak between 419 - 434 nm, measured using a UV-Vis spectrophotometer indicates the existence of AgNPs, this reaction was favored by the increase of temperature with optimal results at 90°C. Synthesis of AuNPs was only obtained using chitosan as reducing agent, the use of solutions of starch and sugars allows the reduction of the gold salt present in the chloroauric acid, however the low pH of the solutions creates thermodynamic instabilities for the AuNP synthesis, due to low repulsive force for colloid stability.

We have compared the rates of CO formation on Cu and Cu oxide surfaces during the electrochemical reduction of CO2 in aqueous media. On metallic Cu surfaces, H2 formation is the main reaction at potentials less cathodic than –1.16 V(NHE). At this potential the formation of CO becomes significant, while CH4 appears at potentials more cathodic than –1.36 V(NHE). On electrodeposited Cu oxide surfaces there is a complex transient response. During reduction at constant potential (–1.1 V(NHE)), there is a large, transient cathodic current that corresponds to reduction of the oxide layer. After this initial oxide reduction, the current density stabilizes and the formation rates of H2 and CO show a more slowly varying transient behavior. The H2 formation rate is roughly 3x higher than on freshly cleaned Cu foil, but is largely independent of the thickness of the initial oxide layer. In contrast, the CO formation rate is at least one order of magnitude higher on the (reduced) Cu oxide samples than on Cu foil at the same potential. These results are interpreted as evidence that CO formation is enhanced at low-coordination number Cu sites present on freshly nucleated Cu clusters following oxide reduction.

The electrochemical decomposition of water is an attractive method, however, the performance of the electrodes and efficiencies are of great concern in its large scale production. In this context, we wish to report here the superior performance of Ni-multiwalled carbon nanotube composite as cathode in the decomposition of water. The current voltage curves recorded with this electrode in different media showed a significant electrocatalysis in the reduction of hydrogen ion; the background electrolysis is shifted in the anodic direction. The nanocomposite composition has been found to be crucial in the efficient production of hydrogen. A coulombic efficiency of about 68% has been obtained at this electrode with a hydrogen production rate of 130L/m2 d. This electrode is more efficient than the 316L stainless steel (composition in percentage: C 0.019, Cr 17.3, Mo 2.04, Ni 11.3, Mn 1.04, N 0.041, Fe bulk) cathode that produces 10 ml/h at an area of 20 cm2 (5L/m2.h) (2). The results obtained with different electrolytes, performance variation with electrode composition, and current densities will be presented. The trials carried out using solar panel instead of DC power source showed similar hydrogen production rates and efficiencies.

Poly(lactic-co-glycolic acid) (PLGA) films with flat surfaces and with 27nm, 190nm, 300nm, 400nm, and 520nm surface features were synthesized using a template method with polydimethylsiloxane (PDMS) molds. The nano patterns were transferred from the self-assembled polystyrene beads to the PLGA films through PDMS molds. After synthesis, the nano patterns were confirmed by AFM height scans. In order to investigate the influence of the materials on bone cells, healthy human osteoblasts were cultured on the PLGA films. The 27nm PLGA surface showed the maximum osteoblast adhesion density and a significant increase compared with the other surface features. For these reasons, and since previous studies have highlighted that similar nanometer surface features on PLGA decreased functions of other cancer cells, this study suggests that PLGA with 27nm surface features should be further studied for bone cancer applications where healthy bone cell functions need to be promoted and cancerous bone cell functions inhibited.

Bisphosphonate (Bp) was adsorbed on the surface of crystalline calciumphosphates (CP); hydroxyapatite (HAp), octacalcium phosphate (OCP) andDicalcium phosphate dehydrate (DCPD). The amount of Bp adsorbed was thelargest for DCPD per unit surface area, while the amount was the largest forHAp per unit weight. The composites of Bp and amorphous calcium phosphate(ACP) were synthesized by titrating calcium acetate solution into phosphatebuffer solution containing Bp. The amount of Bp doped in the composites was366 μg / mg and was approximately 7 times larger than those of Bp adsorbedon the crystalline Calcium phosphates. TG-DTA measurements of a Bp-calciumand the composite indicated exothermic peaks due to Bp combustion, of whichtemperature were shifted to higher temperature for the composite. Bp in thecomposites was gradually released into phosphate buffered saline, while Bpwas rapidly released into acetate buffer solution accompanied with thedissolution of ACP. This result suggests that the composite of Bp and ACPhas potential for a drug-carrier releasing Bp in response to the conditionof osteoclastic bone resorption.

Technetium-99 (99Tc) is a fission product produced during the burning of nuclear fuel and is particularly hazardous due to its long half life (210000 years), relatively high content in nuclear fuel (approx. 1 kg per ton of SNF), low sorption, and high mobility in aerobic environments. During spent nuclear fuel (SNF) reprocessing Tc is released either as a separate fraction or in complexes with actinides and zirconium. Although Tc has historically been discharged into the marine environment more stringent regulations mean that the preferred long term option is to immobilise Tc in a highly stable and durable matrix. This study investigated the feasibility of incorporating of Mo (as a Tc analogue) in a crystalline host matrix, synthesis by solid state synthesis under different atmospheres. Samples have been characterised with X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray absorption spectroscopy (XAS).

The electronic structure of delta plutonium (δ-Pu) and plutonium compounds is investigated using photoelectron spectroscopy (PES). Results for δ-Pu show a small component of the valence electronic structure which might reasonably be associated with a 5f 6 configuration. PES results for PuTe are used as an indication for the 5f 6 configuration due to the presence of atomic multiplet structure. Temperature dependent PES data on δ-Pu indicate a narrow peak centered 20 meV below the Fermi energy and 100 meV wide. The first PES data for PuCoIn5 indicate a 5f electronic structure more localized than the 5fs in the closely related PuCoGa5. There is support from the PES data for a description of Pu materials with an electronic configuration of 5f 5 with some admixture of 5f 6 as well as a localized/delocalized 5f 5 description.

Ba0.6Sr0.4TiO3 (BST) thin films were deposited on La0.5Sr0.5CoO3 (LSCO) buffered Ti substrates. Both BST and LSCO were prepared by sol-gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to investigate the effect of LSCO sol concentration on the crystallinity and surface morphology of the films. The results show that with the increase of LSCO sol concentration, BST films show variation of the structure and dielectric properties. BST films for LSCO of 0.2 mol/L exhibit a better crystallinity and improved dielectric properties, with the tunability, dielectric constant and tanδ of 30%, 420 and 0.028 respectively.

Hydrogen blister rates in Si (100), Si (111) and Ge (100) substrates are compared as a function of annealing temperature and time, for a range of implant energies and fluences. For each material, the rate of blister formation was found to exhibit Arrhenius behavior and to be characterised by a single activation energy over the temperature range examined. The extracted activation energies were 2.28±0.03 eV, 2.17±0.06 eV and 1.4±0.03 eV for (100) Si; (111) Si and (100) Ge, respectively. These results are compared with reported measurements and discussed in relation to proposed models of hydrogen blistering.

We present results on optical degradation of gallium nitride based materials under low energy electron beam irradiation (LEEBI). GaN thin film and GaN/InGaN quantum well samples, grown by metal-organic vapor phase epitaxy (MOVPE), were exposed to a tightly focused (ø = 2 nm, J = 0-130 kA/cm2), rapidly scanning electron beam (e-beam) with energy of 5-20 keV and dose of 0-500 μC/cm2. The irradiation severely reduced the band-to-band photoluminescence of the exposed sample areas. Performing positron annihilation spectroscopy measurements on the irradiated films revealed an important increase of Ga-vacancy concentration as a function of the irradiation dose. Based on the measurements we propose that in-grown passive VGa-Hn complexes are present in MOVPE grown GaN (and its alloys), and are activated by LEEBI.

Resistance spot welding (RSW) of dual-phase (DP) steel subjected to various conditions of cooling rate (holding time) is studied in this work. Lap-shear tensile testing is used in order to evaluate the mechanical performance of the weldments. The microstructure is analyzed through optical and electron microscopy and the hardness is obtained through Vickers method. Results indicate an effective tempered region along the sub-critical heat affected zone in all the samples. A broken morphology accompanied with presence of small carbides within tempered martensite phase is consistently observed. Variations in the cooling rate (holding time) indicate minimal effect on the degree of softening and on the mechanical performance of the welds.

A nanoscale dynamic mechanical analysis (nano-DMA) measurement method has been successfully developed for use in evaluating nanoscale dynamic viscoelastic properties in small-scale polymer materials over a range of non-ambient temperatures from -120 oC to 500 oC. Measurements have been obtained with a nanoindentation measurement system, in which two key techniques are applied. One is a thermal protection system for control and prevention of thermal drift and noise. The other is an environmental control system for preventing corrosion at high temperatures and dew condensation at low temperatures. Measurement reliability was examined by using a combination of a thermal-mechanically stable fused silica and a homogeneous sample of isotropic polyethylene terephthalate (PET). Constant hardness and modulus values of the fused silica from -120 oC to 500 oC indicated that the measurements were not affected by thermal load drift and noise even at elevated temperatures. The PET sample exhibited no significant difference in temperature dispersions of storage elastic modulus, loss elastic modulus and loss tangent between the nanoindentation measurement data and bulk data measured with a conventional DMA method. A practical application involving surface-deteriorated polyethylene (PE) tubes was used to demonstrate the validity and usefulness of this nano-DMA method. Infrared spectroscopic imaging revealed that the surface layer of the PE tubes was oxidized to form a carbonylated (O=C<) layer. The storage elastic modulus and glass-transition temperature of the surface layer were much higher than the corresponding values of the interior. These data indicate a plausible reason for why the PE tube surface deteriorates to form brittle cracks.

Bandgap engineered ZnSxO1-x films were grown on Fluorinated Ethylene Propylene (FEP) substrates and analyzed using transmission spectroscopy. FEP is considered as a potential substrate for application in flexible electronics and semiconductor films.