The vast majority of industrial scale Carbon Nanotube (CNT) production involves short nanotubes (< 100 microns) that appear as a powder. These products are typically utilized as minor components (usually less than 2%) in polymers where they may or may not impart marginal improvements in composite properties. At Nanocomp Technologies we produce large-format CNT material by floating catalyst chemical vapor deposition. This technique produces very long CNTs (> 1 mm) in the gas phase, where entanglement produces large format material of exceptional strength and electrical conductivity. By manipulating the physics and chemistry of the process, the format and properties of the material can be controlled. Post-production processing further enhances the desired material properties. In this way applications such as Armor, Wiring and Cables for aerospace, and Integrated Energy Storage can be realized.

Direct Methanol Fuel Cell, DMFC, technology, can be used for fabrication of sensors for volatile organic compounds like alcohols. A fundamental limitation in DMFC is methanol crossover. In this process methanol diffuses from the anode through the electrolyte to the cathode, where it reacts directly with the oxygen and produces no electrical current from the cell. This also results in poisoning of the cathode catalysts. The designed and fabrication of the sensor is by means of micro electro mechanical systems (MEMS) fabrication technology with electrochemical inputs. To achieve this we have used a passive mode design protocol using COMSOL Multiphysics. The design and simulation would involve optimization of various parameters, in the construction of the cell. We can optimize the overall power density and hence the sensitivity of the sensor by the modification of various parameters like the area of the working electrodes, separation distance and the electrode-electrolyte interface. A passive mode design protocol, for a cm cell area, using various parametric functions, and interfacing Darcy’s law of fluidic flow through a porous medium, under specific pressure and temperature, was applied. The designing involves the construction of gas diffusion layers using carbon cloth for anode and cathode with various parametric variations. Nafion membrane was selected as proton exchange membrane for the construction with different interface structure to analyze the sensor’s performance. Platinum and various alloy catalysts like Pt-Ru, Pt-Fe, Pt-Sn and Pt-Mo was chosen as the working catalysts. The parametric functions of the cell were optimized for ampherometric detection. It is proposed to design a MEMS based sensor with microfludic interconnects and its response characteristics will be studied.

A single-grained Pb(Zr,Ti)O3 (PZT) was successfully grown for the gate dielectric of polycrystalline-silicon (poly-Si) thin-film transistor (TFT). The total structure was MoW/PZT/HfO2/poly-Si/glass. The giant single-grained PZT was obtained by controlling the artificial nucleation formed by Pt dots in a desirable location and enlarging the nucleated seed until it covers the poly-Si channel. The single-grained diameter size was 40 μm with a (100) dominated texture. The poly-Si memory device with single-grained PZT showed an excellent ferroelectric, electrical and reliability properties comparing with poly-Si memory device with poly-grained PZT. Moreover, eliminating the grain boundary in PZT film showed the fatigue and retention characteristics with only 1.1 % after 1013 cycles and 22 % after 1 month, respectively.

The crystal structure of the δ1p phase in the Fe-Zn system has been refined by single-crystal synchrotron X-ray diffraction combined with ultra-high resolution scanning transmission electron microscopy. The crystal structure can be described to build up with Fe-centered Zn12 icosahedra. The deformation properties obtained by single-crystal micropillar compression tests of the δ1p phase is discussed in terms of the arrangement of the Fe-centered Zn12 icosahedra in contrast with the ζ phase in the Fe-Zn system.

Recent research has demonstrated that ternary aluminum-boron-iodine (Al-B-I2) materials prepared by mechanical milling are effective in generating biocidal combustion products. Such reactive materials are of interest for the munitions aimed to defeat stockpiles of biological weapons. In this research, ternary Mg∙B∙I2 composites were synthesized using two-stage milling. The first stage consisted of a binary B∙I2 powder prepared by mechanical milling, followed by addition of magnesium for iodine stabilization. Specific compositions for each ternary material were varied. Stability of the samples was assessed by their heating in argon at a constant rate using Thermo Gravimetric Analysis (TGA) and observing weight loss. Oxidation of the prepared powders was also studied by TGA. Ternary Mg∙B∙I2 composite powders prepared by two-stage milling were more stable than any of the previously prepared iodine-bearing materials with the same concentration of iodine (20 wt %). Particle size distributions were measured using low-angle laser light scattering. Powders were ignited using in an air-acetylene flame and in a constant volume explosion apparatus. Particle burn times and temperatures were measured optically. Substantially longer burn times and lower temperatures were observed for the prepared materials compared to the reference pure Mg powder.

Based on the investigation of mechanism for large dielectric losses in relaxor fluorinated polymers, polyvinylidene fluoride (PVDF) derivatives, a new nanostructure-controlled PVDF based polymer films with low dielectric loss, tanδ < 1% (0.6%), and high dielectric constant, εr = 13 at frequency of 1 kHz, was proposed for electrical energy storage applications. The high dielectric loss was mainly due to the electric-field induced α-β phase transition, and one dimensional extension of P(VDF-TrFE)-g-PEMA films was found to reduce the α phase component resulting in reduction of the dielectric loss while keeping the high dielectric constant. In-situ FTIR measurements suggested a possibility of further reducing the dielectric-loss.

We have studied multigeneration effects of plasma irradiation to seeds of Arabidopsis thaliana (L.) and Zinnia peruviana (L.) on their growth using a scalable DBD device. Atmospheric plasma irradiation enhances growth of these plants in multi-generations. For Arabidopsis thaliana (L.) in the third generation, the leaf area is 2 times larger than that without plasma irradiation and the stem length is 1.5 times longer than that without plasma. For Zinnia peruviana (L.) in the second generation, the stem length is 2 times longer than that without plasma.

Π-conjugated porous polymers with hierarchical pore structures were synthesized via high internal phase emulsion polymerization (polyHIPE) technique. The polymers could be used as heterogeneous photocatalysts for highly selective oxidation of organic sulfides into sulfoxides and the free radical polymerization of methyl methacrylate (MMA) under visible light irradiation.

Nanoscale systems combining colloidal quantum dots with plasmonic antennas will pioneer the development of novel nanodevices with tailored optical features for a wide range of applications. The interactions between such nanoparticles strongly depend on the particular distance. We propose the use of an atomic force microscope (AFM) to image and to position quantum dots with respect to plasmonic particles. Additionally, we analyze the arrangements with several optical characterization methods, such as confocal microscopy, fluorescence microscopy and superresolution optical fluctuation imaging (SOFI). These methods support each other and improve the AFM manipulation technique. The AFM tip is perfectly aligned to a focused laser by detecting the Raman signal of the silicon tip. Thus ultimately, we can simultaneously use the topography information with a spatial resolution in the range of the nanoparticle sizes and cross-correlate it with the optical characterization methods.

The local detection of optical response at the sub-wavelength scale on a materials’ surface is an invaluable characterization capability of apertureless scanning near-field optical microscopy (ASNOM). The technique is traditionally realized in amplitude modulation (AM) AFM mode. We have expanded this method by employing an alternative scheme for the detection of the near-field and far-field responses with the use of Hybrid (HD) AFM mode. In HD mode the sample is brought to the intermittent contact with the tip in a periodic oscillation at a frequency (1-2 kHz) much smaller than the probe resonance. In every oscillation cycle the probe deflection to a set-point value is used for surface profiling. For optical measurements the metal coated AFM tip was top-illuminated by visible laser. Simultaneously with surface profiling the light scattered from tip-sample junction was collected by a sensitive photomultiplier (PMT). The homodyne optical signal detection scheme was applied to discriminate near- and far-field optical components. Our method was verified by the studies of various materials (semiconductors, metals, polymers, etc.). The presented results show that the contrast of ASNOM images can be used for compositional mapping of heterogeneous systems.

6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) was deposited on SiO2/Si substrates with Au stripes using electrostatic spray deposition (ESD). We observed that crystalline domains on the substrates were preferentially oriented. To elucidate this phenomenon, the correlation between the orientation direction and stripe direction was investigated by angle-dependent polarized Raman spectroscopy. Since the acene planes in TIPS pentacene take an edge-on orientation on the substrates, C-C ring stretch modes can be used to probe the in-plane orientation. We found that the long molecular axis of acene planes is inclined at about 50° or 110° from the stripe direction. This result suggests that the molecular orientation of the crystalline domains can be controlled by the stripes.

Cadmium Zinc Telluride (CZT), considered as a viable material for use in room temperature radiation detectors, has an undesired presence of tellurium inclusions in the bulk. Thermal treatment, in the form of annealing, has been utilized to test the viability of refining CZT into better detector material, either by the elimination of the tellurium inclusions or by the migration of the inclusions under a temperature gradient, but usually with a deterioration of electrical properties. We took infrared micrographs and current voltage (IV) characteristics of CZT samples prior to thermal treatment. We carried out 24-hour thermal treatments with a range of temperature from 100°C to 700°C to determine an optimal annealing temperature and to verify changes in the sizes, morphologies, and locations of the tellurium inclusions on the surfaces and within the crystal bulk of the CZT. The IV curves and resistivities prior to and after thermal treatments were compared, as were the infrared micrographs before and after annealing. Also, the changes in electrical properties of the samples with annealing conditions were compared against structural changes monitored at the same steps during the annealing process, in order to understand the effects of the thermal annealing to the radiation detector properties of the material. Correlations between the shape, size and position of inclusions and electrical properties of the material were attempted.

The interface with reactive transport models used in performance assessment calculations is described to identify aspects of the glass waste form degradation model important to long-term predictions. These are primarily the conditions that trigger the change from the residual rate to the Stage 3 rate and the values of those rates. Although the processes triggering the change and controlling the Stage 3 rate are not yet understood mechanistically, neither appears related to an intrinsic property of the glass. The sudden and usually significant increase in the glass dissolution rate suggests the processes that trigger the increase are different than the processes controlling glass dissolution prior to that change. Application of a simple expression that was derived for mineral transformation to represent the kinetics of coupled glass dissolution and secondary phase precipitation reactions is shown to be consistent with experimental observations of Stage 3 and useful for modeling long-term glass dissolution in a complex disposal environment.

Understanding, predicting and eventually improving the resistance to fracture of silicate materials is of primary importance to design new glasses that would be tougher, while retaining their transparency. However, the atomic mechanism of the fracture in amorphous silicate materials is still a topic of debate. In particular, there is some controversy about the existence of ductility at the nano-scale during the crack propagation. Here, we present simulations of the fracture of three archetypical silicate glasses using molecular dynamics. We show that the methodology that is used provide realistic values of fracture energy and toughness. In addition, the simulations clearly suggest that silicate glasses can show different degrees of ductility, depending on their composition.

The physical mechanisms responsible for electrically-induced parametric degradation in GaN-based high electron mobility transistors are examined using a combination of experiments, device simulation, and first-principles defect analysis. A relatively simple formulation is developed under the assumption that the hot-electron scattering cross-section is independent of the electron energy. In this case, one can relate the change in defect concentration to the operational characteristics of a device, such as the spatial and energy distribution of electrons (electron temperature), electric field distribution, and electron energy loss to the lattice.

The reactions of 2-cyano-3-ferrocenylacrylonitrile with malononitrile in a ROH/H2O medium in the presence of Na2CO3 afforded 6-alkoxy-2-amino-4-ferrocenylpyridine-3,5-dicarbonitriles, 6-alkoxy-2-amino-4-ferrocenyl-3-ferrocenyl-methyl-3,4-dihydropyridine-3,5-dicarbonitriles and Na+ polymeric complexes: {[Na+(2-ferrocenyl(tetracyano)propenyl)−L]∞ and [Na+(2-amino-3,5-dicyano-4-ferrocenyl-6-pyridyl-dicyanomethyl)−L]∞ where L = ethanol, methanol. Complexes with L = acetonitrile (c), dimethylformamide (d), acetone (e), ethyl acetate (f) were prepared by recrystallization. The structures of the compounds 4b and Na+ polymeric complexes 5c and 6d, e were established by the spectroscopic data and X-ray diffraction analysis. Two compounds 3a and 4a were tested in vitro against six human tumor cell lines U-251, PC-3, K-562, HCT-15, MCF-7 and SKLU-1 to assess their in vitro antitumor activity. The results suggest biological specificity towards PC-3, K-562 and HCT-15 cells for compound 3a, and towards PC-3 cell for compound 4a at doses 50 μM, which are lower than Cisplatin IC50 ′s in the three cell lines.

3D printing is a versatile fabrication method that offers the potential to realize complex 3D devices with metamaterial characteristics in a single process directly from a computer aided design. However, the range of functional devices that might be realized by 3D printing is limited by the current range of materials that are compatible with a given 3D printing process: fused deposition modelling (FDM), which is a widely used 3D printing method, typically employs only common thermoplastics. Here we describe the development of a magnetic feedstock based on polymer-ferrite composite that is compatible with FDM. The feasibility of the technique is demonstrated by the permittivity and permeability measurement of direct printed blocks and the fabrication of a complex 3D diamond-like lattice structure. The development of printable magnetic composites provides increased design freedom for direct realization of devices with graded electromagnetic properties operating at microwave frequencies.

Thermoelectric (TE) materials have been studied during past decades since they can generate electricity directly from waste heat. Antimony chalcogenides (Sb2M3, M = S, Se, Te) are well known as one of the promising candidates among the inorganic TE materials. We report on the synthesis of Sb2Te3 nanoparticle via thermolysis method. A systematic study was done to investigate the effect of reaction time and ratio between the precursors as well as the method of cooling on the morphology and composition of obtained nanoparticles. The ratio between precursors was varied to study the effect on the morphology. Furthermore, the high purity phase Sb2Te3 was obtained by a rapid cooling process.

We have investigated the solidified microstructure of nucleation-generated grains obtained via complete melting of Si films on SiO2 at high nucleation temperatures. This was achieved using a high-temperature-capable hot stage in conjunction with excimer laser irradiation. As predicted by the direct-growth model that considers (1) the evolution in the temperature of the solidifying interface and (2) the subsequent modes of growth (consisting of amorphous, defective, and epitaxial) as key factors, we were able to observe the appearance of “normal” grains that possess a single-crystal core area. These grains, which are in contrast to previously reported flower-shaped grains that fully make up the microstructure of the solidified films obtained via irradiation at lower preheating temperatures (and amongst which these “normal” grains emerge), indicate that epitaxial growth of nucleated crystals must have taken place within the grains. We discuss the implications of our findings regarding (1) the validity of the direct-growth model, (2) the nature of the heterogeneous nucleation mechanism, and (3) the alternative explanations and assumptions that have been previously employed in order to explain the microstructure of Si films obtained via nucleation and growth within the complete melting regime.