We report a novel method for synthesizing electrically conductive nano-brush (CNB) by physical grafting of organic conducting polymers on carbon nano tubes (CNT). The objective for this synthesis is to produce nano tubes having a CNT stem coated with flexible electronic conducting polymers. The nano-brush is to be blended into common polymers (e.g. epoxy, polyurethane, and poly(vinyl alcohol)) to form electrically conductive composite material. The flexible organic conducting polymer in CNB is a potentially sensitive electronic probe for mechanically induced nano-deformation of the composite because it is molecularly entangled with the host polymers. The electrical networks of CNB embedded in polymeric composites are potentially useful as in situ sensors for monitoring material deformation with an unprecedented level of sensitivity. The composite material is “smart” in the sense that it self-reports the structural “health” before load induced material failure.

Our method for grafting conducting polymer does not require chemical reactions with the surface atoms of the carbon nano tube. We used physical adsorption to graft electronic conducting polymer to CNT. We first synthesized a water-soluble electronic conducting polymer which is a molecular complex between poly(acrylic acid) and polyaniline. The CNT solid were dispersed and un-bundled by sonnication in the conducting polymer solution. Due to the high affinity between CNT and the conducting polymer, the surface of CNT can be fully covered with the conducting polymer. The experimental data is consistent with a structure of nano brush with high density of conducting polymers grafted on the CNT surface.

We briefly review some recent results on the steady-state and transient electron transport that occurs within bulk wurtzite zinc oxide. These results were obtained using an ensemble semi-classical three-valley Monte Carlo simulation approach. They showed that for electric field strengths in excess of 180 kV/cm, the steady-state electron drift velocity associated with bulk wurtzite zinc oxide exceeds that associated with bulk wurtzite gallium nitride. The transient electron transport that occurs within bulk wurtzite zinc oxide was studied by examining how electrons, initially in thermal equilibrium, respond to the sudden application of a constant electric field. These transient electron transport results demonstrated that for devices with dimensions smaller than 0.1 μm, gallium nitride based devices will offer the advantage, owing to their superior transient electron transport, while for devices with dimensions greater than 0.1 μm, zinc oxide based devices will offer the advantage, owing to their superior high-field steady-state electron transport.

In high level radioactive glasses, the low solubility platinoids (Pd, Ru, Rh) precipitate to form (Pd-Rh-Te, Ru-Rh, Ru) metallic particles and (RuO2, Rh2O3) oxides during the vitrification process. The composition and microstructures of these phases can significantly modify the physico-chemical properties and the electrical or thermal conductivities during melting.

Several studies are undertaken at CEA in order to point out the reactions and the chemical interactions in the liquid and viscous states between the glass matrix and the platinoids present in the calcinated waste. Among these studies, a thermodynamic fission products database is being developed on the metallic (Pd-Rh-Ru-Te) and oxide (O-Pd-Rh-Ru-Te) systems. In this work, based on the Calphad method, the Gibbs free energies of each phase are modelled to provide an overall thermodynamic description of the platinoid phases in nuclear waste glasses. The objective of the database is to facilitate calculations of phase diagrams and thermodynamic properties. This flexible tool also enables calculations of the relative stability between metallic and oxide phases in function of the oxygen potential (RedOx equilibrium).

For example, some solidification routes are calculated for typical Pd-Rh-Ru-Te compositions of LWR spent fuels. The calculated Pd-Rh-Ru-Te solidification paths are compared with the phases analysed in simplified laboratory scale glass samples. Using these results, the compositions of the Pd-Rh-Ru-Te inclusions are predicted. Furthermore, possible consideration of the RedOx equilibria for some ruthenium based phases makes it possible to explain the speciation between oxide and metallic phases partly due to the Pd-Te interaction.

The performance of tunnel FETs is investigated and the impact of device structure and dimension as well as the impact of the transistor material will be studied. For instance, using nanowires with thin diameter providing one-dimensional transport together with a wrap-gate device structure strongly improves the tunnel FET performance. In addition, the use of III-V type II heterostructures is a further performance booster. However, the use of III-V semiconductors with low density of states can be problematic if the device is not designed properly. Here we will give design guidelines and performance predictions of nanowire tunnel FETs based on non-equilibrium Greens functions formalism simulations.

One consequence of “high stakes testing” in Tuscaloosa area schools has been exclusion of materials science faculty from any meaningful participation in middle and high school classrooms. Beyond the loss of resources from the classroom that Materials Science faculty and their students represent, this also has negative consequences for faculty wanting to build ties to schools to address NSF’s “broader impact” criteria. A group of STEM and Education faculty at The University of Alabama have been testing a team based approach designed to overcome the systemic constraints that prevent effective STEM/K-12 collaboration. Teams consisting of a high school teacher, a STEM faculty member, and a STEM graduate student have spent three weeks during summer 2010 to identify/develop and implement an inquiry based science experiments. The experiments are being tested on science campers at McWane Science Center prior to being assessed in the teachers’ classrooms during the fall semester. The experiments were chosen by each team and represent significant advances over those currently available in the schools. By setting a problem that no team member is able to solve alone an environment was produced where success requires meaningful collaboration. Preliminary qualitative evaluation indicates deeper understanding of the school environment by the STEM faculty and greater respect for the skills teachers bring to this endeavor. Successes in this pilot program have generated credibility with the local school district, opening the door to scaling up the project, and developing further positive ties. Incorporation of lead teachers from Alabama Science in Motion also allows the experiments developed to be widely disseminated throughout Alabama, as well as providing a mechanism to identify existing experiments to enhance.

Gongyi is the birthplace and one of the most famous production areas of white porcelain in China. In this study, white porcelain samples from the Northern Wei to Tang Dynasties excavated from Baihe and Huangye kiln sites were analyzed to investigate microstructure and its physicochemical basis. The result demonstrates that the formation of an interaction layer of Anorthite crystals and the accompanied phase-separation structure at glaze-body boundary is a common character of microstructure. And there is little probability for crystal precipitation within the glaze layer.

Preparation of transparent silica as potential carrier for photocatalysts and photosynthetic bacteria is presented. SiO2 was obtained by sol-gel techniques using tetraethyl orthosilicate as precursor. Glycol and glycerol were used as solvents. The increase of porosity of the studied materials was reached by application of soluble and commercial potato starch as a filler. Calcinations at 825 K for 6 hours removed all organic compounds. The rate of gelation was enhanced applying hydrochloric acid. Different materials were obtained in a series of syntheses with different concentrations of individual components. Transparency of the obtained materials varied between 50 and 97% (in range of λ 350 - 800 nm). Surface area varied between 300 and 400 m2/g and pore diameter was 5 – 18 nm. Samples were studied with SEM, nitrogen sorption at 77 K and UV-Vis spectroscopy. The obtained transparent materials with occluded TiO2 or CaTiO3 were tested in photocatalytic splitting of water.

Atomic layer deposition (ALD) has been used to coat SBA-15 and functionalized SBA-15 with various metal oxides. Use of SBA-15 coated with 4-10 ALD cycles of titania, alumina, niobia, or zirconia in the acid-catalyzed dehydration of fructose to 5-hydroxymethylfurfural (HMF) resulted in 24-57% conversion, with 0-22% selectivity, at 130 °C with 2 wt % fructose in 4:1 THF:H2O. Propylsulfonic acid functionalized SBA-15 (SBA-15-PrSO3H) had a 25% conversion and 48% selectivity for HMF under the same conditions. SBA-15-PrSO3H was also coated with 2 ALD cycles of titania followed by 8 ALD cycles silica. The deactivation rate constant for SBA-15-PrSO3H was 2.7 x 10-2 h-1 for the dehydration of fructose to HMF in a flow reactor at 130 °C with a feed of 2 wt % fructose in 4:1 THF:H2O. In comparison, the deactivation rate constant for the ALD coated SBA-15-PrSO3H-ALD was 7.9 x 10-3 h-1.

A new chemical vapor deposition method for the growth of ZnO films using the reaction between dimethylzinc (DMZn) and thermally excited H2O produced by a Pt-catalyzed H2–O2 reaction was investigated. The thermally excited H2O molecules formed by the exothermic reaction of H2 and O2 on the catalyst were ejected from a fine nozzle into the reaction zone and allowed to collide with DMZn ejected from another fine nozzle. The ZnO films were grown directly on a-plane (11-20) sapphire substrates at substrate temperatures of 773-873 K with no buffer layer. X-ray diffraction patterns exhibited intense (0002) and (0004) peaks from the ZnO(0001) index plane. The smallest full width at half maximum (FWHM) value of the ω- rocking curve of ZnO(0002) was less than 0.1º. The largest Hall mobility and the smallest residual carrier concentration of the ZnO films were 169 cm2V−1s−1 and 1.7×1017 cm−3, respectively. Photoluminescence (PL) spectra at room temperature exhibited a band edge emission at 3.29 eV, with a FWHM of 104 meV. Green luminescence from deeper levels was generally about 1.5% of the band edge emission intensity. PL spectra at 5 K showed a strong emission peak at 3.3603 eV, attributed to the neutral donor-bound exciton Dºx. The FWHM was as low as 1.0 meV. Free exciton emissions also appeared at 3.3757 eV (FXA, n=1) and 3.4221 eV (FXA, n=2).

High-current-density cathodes are required for the development of high-power mm-wave and upper mm-wave devices, as well as for other electron beam applications. To address this need, a current amplifier stage is being developed that will multiply a primary electron-beam current (via the secondary-electron multiplication process) and then emit the amplified beam so as to achieve a current gain of 50-100. Diamond is a particularly promising current amplification source due to the negative electron affinity present at stable hydrogenated surfaces. As such, we are fabricating current amplifiers using single-crystal CVD diamond grown at NRL, with our growth effort focused on reducing the impurity concentration in the epitaxial diamond and on fabricating microns-thick freestanding films. The current amplification characteristics of the diamond films are examined using secondary-electron-emission measurements in both reflection and transmission configurations. In our initial study of an 8.3-µm-thick CVD diamond film, the single-crystal diamond is shown to have superior transport and emission properties compared to similar polycrystalline material. While transmission gains have been obtained under field-free conditions from the unbiased diamond film, we are striving to increase the gain by increasing the transport efficiency in a biased amplifier structure. Towards this end, recent efforts have focused on optimizing the bonding and metallization processes as needed to establish and control the internal electric field. In addition, Monte Carlo simulations are being used to predict the optimal material and device parameters needed to achieve high amplifier gain and low energy spread.

We studied the thickness variation of equally doped ZnO:Al films used as conductive window layer in Cu(In,Ga)(Se,S)2 (CIGSSe) thin film solar cells. The IV-characteristics of solar cells with window layer thickness of d1=200nm exhibit a strong enhancement of the short-circuit current density JSC (ΔJSC = 3mA/cm2) as compared to samples with module-like ZnO:Al-film thickness (d2=1200nm). Accordingly, the quantum efficiency reveals the spectral regimes where the JSC-gain occurs. Moreover, current-voltage measurements reveal that the cells with thicker ZnO:Al exhibit slightly decreased open circuit voltage VOC. This finding can be assigned to a decreased net-doping density NA, which appears to be introduced by additional heat flux during the longer process time required for deposition of thicker ZnO:Al films. However, the improved efficiency of solar cells with thinner window layer comes along with an increase of the series resistance (RS) by almost a factor of 2, which will have consequences for the series connection of elements in a module. XRD-diffractograms and SEM cross-section imaging suggest that the enhanced RS in cells with thin ZnO:Al is not exclusively related to the thickness but is also due to a reduced (002)-texture and an elongated lateral charge carrier pathway.

We have developed the pressure annealing technique for fabricating low work function metal pattern on plastic substrate. In general, the difficulty to print conductive low work function metal patterns is caused by the insulating metal oxide layer covering on metal particles included in metal paste. The pressure annealing technique can destruct the metal oxide layer and can form conductive layer on printed metal pattern. Further, we have confirmed that a binary solid solution is easily formed on metal patterns including two kinds of metal particles by using the pressure annealing technique. Changing the composition ratio of the binary metal paste led to the work function control of the pressure-annealed metal patterns. Formation of the binary solid solution was confirmed by using XRD spectra, and work function values were measured by using photoelectron emission spectra. In the case of the binary metal paste of Cu and Zn, we have succeeded in controlling work function from 3.8 eV to 5.0 eV. Since the Cu-Zn paste is composed of relatively low price metals, this would be applicable to large-scale flexible electronic devices.

Particulate zinc oxide (ZnO) is a known antibacterial agent. Studies have shown that reducing the size of ZnO particles to nanoscale dimensions further enhances their antibacterial properties. Polymers, like all biomaterials, run the risk of harboring bacteria which may produce an antibiotic-resistant biofilm. The addition of ZnO nanoparticles, to form a composite material, may reduce undesirable bacteria activity. The purpose of the present in vitro study was to investigate the antibacterial properties of ZnO nanoparticles when incorporated into a polymer biomaterial. Staphylococcus aureus were seeded at a known cell density onto coverslips coated in a film of polyvinyl chloride (PVC) with varying concentrations of ZnO nanoparticles. Samples were cultured for 24 or 72 h. Methods of analysis, including optical density readings and crystal violet staining, indicated a reduced presence of biofilm on ZnO nanoparticle and polymer composites compared to polymer control. Live/dead assays provided images to confirm reduced presence of active bacteria on samples with zinc oxide nanoparticles. Development of this technology may improve biomaterial effectiveness for applications, such as endotracheal tubes and implanted biomaterials, which are prone to bacterial infection.

In this paper we review the phase diagram and derive the entropy change for spin reorientation transitions by considering first order magnetization process theory with temperature dependent magneto-crystalline anisotropy constants. We derive the magnetic field-induced entropy change Δs for a transition between easy axis and easy plane, showing that for alternating magnetic field, Δs has a change of sign at the reorientation temperature, while for rotating magnetic field its sign is definite. We apply the model to CoZn W-type barium ferrite.

There are a lot of synthetic polymers which can be used for controlled drug delivery, however they are not easily accepted by the organism. Also incorporation of drugs into carriers runs under difficult conditions. Therefore scientists have been inclined to use natural-origin polymers, such as proteins and polysaccharides. Some of these promising natural polysaccharidic candidates are alginic acid sodium salt, guar gum and chitosan due to their outstanding merits. They are similar to extracellular matrix having high chemical versatility, good biological performance and cell or enzyme-controlled degradability. Many polysaccharidic hydrogels for drug delivery have already been prepared, but one of their weakness is their short life in dry air conditions; thus, special coating materials are being developed for enhancing their life time.

Alginates were used in the present research for synthesis of organic biodegradable gels by sol-gel process, which were further easily converted to aerogels by supercritical drying. They are safe for use, nontoxic, and derived from renewable sources. Aerogels made of alginate are dry and stable materials, which makes them interesting as a substitute to hydrogels. Alginates undergo reversible gelation in aqueous solution through interaction with divalent cations such as Ca2+, which create ionic inter-chain bridges. Two fundamental methods of ionic cross-linking were used to prepare alginate hydrogels: the diffusion method, where spheres are created and the internal setting method resulting in monoliths. After producing the hydrogel, alcogels were formed by solvent exchange using 100% ethanol. Ethanol was later replaced by supercritical CO2 with supercritical drying (100 bar, 35°C). Aerogels made from natural polysaccharides combine both biocharacteristics and aerogel characteristics such as high porosity and specific surface area, which makes them really attractive in drug delivery applications. The aerogels obtained in present research were therefore studied as drug carriers. The effects of the alginate composition and synthesis method on model drug nicotinic acid release were investigated. The results indicated that by using the internal setting cross-linking method for obtaining aerogels nicotinic acid was released in a more controlled manner. That is why further investigation was done on alginate spherical beads for prolonging their drug release. A multi-step sol-gel process was applied to generate complex aerogels with multi-membranes. First ionically cross-linked spherical cores were obtained by dropwise addition of sodium alginate solution into a CaCl2 solution. These cores were further immersed into alginate solution, filtered through a sieve and dropped into a salt solution again. By repeating the above process, different multi-membrane hydrogels were produced and further converted to aerogels. By adding more membranes around core burst drug release was successfully inhibited.

The low cycle fatigue (LCF) behaviour of two cast as well as two hot extruded Fe3Al-based iron aluminide alloys, either with or without Cr, is investigated. All four alloys contain microalloying additions of Zr, Nb, C and B. Fatigue tests were carried out under strain control for strain amplitudes in the range of εa = 0.1 – 0.4 % for the cast alloys and εa = 0.1 – 0.7 % for the extruded materials, at frequencies of 1 Hz (extruded Fe3Al) and 3 Hz (all other alloys) and at room temperature and 300 °C. Within the first cycles all alloys show strong cyclic hardening. Furthermore the fatigue strain – fatigue life curves are steeper at 300 °C than at room temperature, showing increased fatigue strength at low cycle numbers due to increasing ductility and decreased fatigue strength at increasing cycle numbers because of reduced yield strength. Cr is found to have only a negligible influence on the fatigue behaviour of Fe3Al-based alloys. Comparison between the differently processed materials shows superior LCF properties of the hot extruded iron aluminides due to significantly smaller grain sizes.

High quality polycrystalline silicon (poly-Si) thin film solar cell was successfully fabricated on soda-lime glass substrates by electron beam (Ebeam) evaporation at low processing temperature. The initial poly-Si seed layer (p+-type 0.5 μm thick) was grown via the aluminum induced crystallization (AIC) method at 450 °C. Prominent interdiffusion and Si crystallization have been observed. X-ray diffraction (XRD) shows that (111) is the dominating crystalline orientation. Post annealing at 450 °C for six hours has produced densely packed Si grains with dimension of more than 10 μm in the plane of the film. Non-destructive Raman spectroscopy reveals the remarkable crystalline improvement for samples after thermal treatment. After removing the top diffused Al by chemical means, an absorber layer (p-type) of 0.9 μm thick was subsequently deposited onto the seed layer by Ebeam evaporation at 500 °C. Transmission electron microscopy (TEM) confirmed good homo-epitaxial growth. Without breaking the high vacuum, an n-type amorphous Si (a-Si) layer (0.7 μm thick) was coated onto the absorber layer to form p-n junction. The corresponding I-V characteristics suggest that our low temperature processing technique is applicable for production of poly-Si thin film solar cell on low cost substrates.

In order to investigate the formation of precipitates such as MC carbides and intermetallic compounds in the friction stir welded and post-heat-treated Inconel 718 alloy, this work was carried out. Furthermore, the microstructural and mechanical properties of welds and post-heat-treated material were evaluated to identify the effect on precipitates formed during post-heat-treatment. Friction stir welding (FSW) was performed at a rotation speed of 200 rpm and welding speed of 150 mm/min; heat treatment was performed after welding at 720 °C for 8 hours in vacuum. As a result, the grain size due to FSW was notably refined from 5–20 μm in the base material to 1–3 μm in the stir zone; this was accompanied by dynamic recrystallization, which resulted in enhancements in the mechanical properties as compared to the base material. In particular, applying heat treatment after FSW led to improvements in the mechanical properties of the welds—the microhardness and tensile strength increased by more than 50% and 40% in fraction, respectively, as compared to FSW alone.

Energy-filtered transmission electron microscopy (EFTEM) yields new possibilities for the investigation of Bi2Te3 based nanomaterials. Combined low-loss electron energy-loss spectroscopy (EELS) and energy-dispersive x-ray microanalysis (EDS) and energy-filtered TEM were applied on a Zeiss 912Ω TEM to investigate nanowires, thin films, and bulk materials. Multilayered Bi-Sb-Te nanowires with a diameter of 65 nm and a period of 200 nm and stoichiometric Bi2Te3 nanowires were grown by potential-pulsed electrochemical deposition. Tellurium elemental maps of the multilayered nanowires were obtained by two-window edge-jump ratio images (EJI). EDS chemical analysis showed that small Te fluctuations of 3 at.% yielded significant contrast in EJI. Energy-filtered TEM applied on nano-alloyed Bi2Te3 thin films grown by molecular beam epitaxy (MBE) revealed 10-20 nm thick Bi-rich blocking layers at grain boundaries. Plasmon spectroscopy by EELS was applied on Bi2(Te0.91Se0.09)3 bulk and yielded a plasmon energy of 16.9 eV. Finally, plasmon dispersion was measured for Bi2(Te0.91Se0.09)3 bulk by angle-resolved EELS, which yields a fingerprint of the anisotropy and the dimensionality of the electronic structure of the materials.

The morphological evolution of Mg based powders during repeated absorption-desorption reactions with hydrogen has been studied by Scanning Electron Microscopy. The main feature observed is the presence, after several cycles, of surface protrusions probably constituted by the base Mg material without the presence of a catalyst. The effect is present both in catalyzed and non-catalyzed materials and it is considered an indication of the tendency of the base material to exit from the oxide shell surrounding the Mg powder particles. This tendency is confirmed by the observation of empty MgO boxes indicating that the effect can push until a complete expulsion of the base material. This effect can represent the base for an innovative method for cleaning the surface of a tank material by an “in situ” procedure.