In its relatively short history as a Raman laser material, CVD diamond has already demonstrated to be a forerunner in performance. Yet the more outstanding properties of the material such as its high thermal conductivity and wide transmission range remain largely unexploited. This paper summarizes the recent studies aimed to extend diamond laser capability beyond that readily achievable using other materials, focusing on in particular diamond Raman lasers in the ultraviolet, infrared and at high average powers.

Ultrasonically generated forces are well known for dispersing and deagglomeration of small volumes in laboratory and bench-top scale. By the evaluation and optimization of the most important ultrasonic parameters and the development of large scale ultrasonic machinery, ultrasound forces can be applied also for particle size reduction and wet-milling of nano-particles in industrial scale.

A hybrid assembly was built using ZnO nanowire (NW) arrays and colloidal CdSe quantum dots (QDs) stabilized by 3-mercaptopropionic acid (MPA). The QDs were chemically linked to the nanowires through the bonds formed between the outgoing carboxyl groups of the QD stabilizers and the zinc ions on the nanowire surface. An efficient clustering attachment of the QDs was achieved via partial removal of the stabilizers of the QDs. The photoconductivity of the NW/QD assembly was investigated by selective excitation of the CdSe QDs. Oxygen desorption from the nanowire surface enhances the photoconductivity and a model involving electron transfer between the QDs and the nanowires is proposed to explain the experimental results.

The safe management and disposition of used nuclear fuel and/or high level nuclear waste is a fundamental aspect of the nuclear fuel cycle. The United States currently utilizes a once-through fuel cycle where used nuclear fuel is stored on-site in either wet pools or in dry storage systems with ultimate disposal in a deep mined geologic repository envisioned. However, a decision not to use the proposed Yucca Mountain Repository will result in longer interim storage at reactor sites than previously planned. In addition, alternatives to the once-through fuel cycle are being considered and a variety of options are being explored under the U.S. Department of Energy’s Fuel Cycle Technologies Program.

These two factors lead to the need to develop a credible strategy for managing radioactive wastes from any future nuclear fuel cycle in order to provide acceptable disposition pathways for all wastes regardless of transmutation system technology, fuel reprocessing scheme(s), and/or the selected fuel cycle. These disposition paths will involve both the storing of radioactive material for some period of time and the ultimate disposal of radioactive waste.

To address the challenges associated with waste management, the DOE Office of Nuclear Energy established the Used Fuel Disposition Campaign in the summer of 2009. The mission of the Used Fuel Disposition Campaign is to identify alternatives and conduct scientific research and technology development to enable storage, transportation, and disposal of used nuclear fuel and wastes generated by existing and future nuclear fuel cycles. The near-and long-term objectives of the Fuel Cycle Technologies Program and its’ Used Fuel Disposition Campaign are presented.

An experimental investigation about the thermoelectric properties of heavily doped p ad n-type nanocrystalline silicon nanowires (NWs) is described. The NWs are produced with low cost CMOS compatible processes, highly customizable in terms of cross-section and placement, which enables the fabrication of both stacked NWs in nearly vertical arrays within nanostructured templates built with SiO2/Si3N4 thin films and individual, freestanding NWs suited for thermal conductivity measurements. The cross-section dimensions of the investigated NWs range between 30 and 120 nm in size and up to about 2 cm in length. The structure of the NWs, as shown by SEM/TEM observations, is nanocrystalline with average size of the nanocrystals in one dimension that is comparable with the nanowire diameter. On the NWs, Seebeck coefficient, electrical resistivity and thermal conductivity have been measured, yielding thermoelectric figure of merit (ZT) values of 0.2 at 300 K for the best case.

A transverse (d 33) mode piezoelectric cantilever was fabricated for energy harvesting. Various dimensions of interdigital electrodes (IDE) were deposited on a piezoelectric layer to examine the effects of electrode design on the performance of energy harvesters. Modeling was performed to calculate the output power of the devices. The estimation was based on Roundy’s analytical modeling derived for a d 31 mode piezoelectric energy harvester (PEH). In order to apply the Roundy’s model to d 33 mode PEH, the IDE configuration was converted to the area of top and bottom electrodes (TBE). The power conversion in d 33 mode PEH was commonly estimated by the product of piezoelectric layer’s thickness and finger electrode’s length. In addition, the spacing between fingers was regarded as gap between top and bottom electrodes. However, the output power in a transverse mode PEH increases continuously with the increase of finger spacing, which does not correspond to experimental results. In this research, the dimension of IDE was converted to that of TBE using conformal mapping, and variation of power of PEH was remodeled. The modified model suggests that the maximum power in a transverse mode PEH is obtained when the finger spacing is identical with effective finger spacing. The output power then decreases when finger spacing is larger than effective finger spacing. The decrease of efficiency may result from insufficient degree of poling and increased charged defect with increasing finger spacing.

We report on the atomic ordering of B-site transition-metals and magnetic properties in double-perovskite oxides, La2CrFeO6 (LCFO) and La2VMnO6 (LVMO), which have never been reported to exist in ordered forms. These double-perovskite oxides are particularly interesting because of possible ferromagnetism (expected from the Kanamori-Goodenough rule for LCFO) and half-metallic antiferromagnetism (predicted for LVMO). Using pulsed-laser deposition technique with single solid-solution targets, we have prepared epitaxial films in ordered forms. Despite similar ionic characters of constituent transition-metals in each compound, the maximum B-site order attained was surprisingly high, ∼90% for LCFO and ∼80% for LVMO, suggesting a significant role of epitaxial stabilization in the spontaneous ordering process. Magnetization and valence state characterizations revealed that the magnetic ground state of both compounds was coincidently ferrimagnetic with saturation magnetization of ∼2μ Bper formula unit, unlike those predicted theoretically. In addition, they were found to be insulating with optical band-gaps of 1.6 eV and 0.9 eV for LCFO and LVMO, respectively. Our results present a wide opportunity to explore novel magnetic properties of binary transition-metal perovskites upon epitaxial stabilization of the ordered phase.

Iron magnetic nanoparticles were synthesized under an inert atmosphere via the reaction between FeCl3 and NaBH4 in droplets of water in a microemulsion consisting of octane with cetyl trimethylammonium bromide and butanol as surfactants. A thin Fe3O4 layer was produced on the iron nanoparticles using slow, controlled oxidation at room temperature. A silica shell was deposited on the Fe3O4 using 3-aminopropyltrimethoxysilane following the method of Zhang et al. [Mater. Sci. Eng. C 30 (2010) 92–97]. The structure and chemistry of the resulting nanoparticles were studied using variety of methods and their magnetic properties were determined. The diameter of the iron core was typically 8-16 nm, while the thickness of the Fe3O4 shell was 2-3 nm. The presence of the silica layer was confirmed using Fourier transform infra-red spectroscopy and the number of NH2-groups on each nanoparticle was determined based on colorimetric tests using ortho-phthalaldehyde.

We describe a simple drop-cast processing method to synthesize multicomponent polymer-based nanocomposites for carbon dioxide (CO2) capture and conversion into stable carbonates. These multicomponent nanocomposites are made of combination of different metal oxide nanoparticles and catalysts in a porous polymer matrix. The formulation includes the combination of titanium dioxide and magnesium oxide, ruthenium oxide, and iron oxide where each metal oxide exhibits its own catalytic function of trapping carbon dioxide. Such a material system provides numerous localized catalytically active hot reaction spots generated by the dispersed multifunctional oxide nanoparticles that react with CO2 when exposed to the gas stream and instantaneously convert the captured carbon into carbonates. Finally, we discuss our ongoing work on the possibility of converting captured-carbon-formed-carbonate into useful products/commodities such as methane, methanol and formic acid. The integration of polymer materials with catalytically active nanomaterials shows a promising strategy for CO2 capture and conversion into useful products towards achieving a sustainable energy future.

This article describes design of fullerene-based electron-accepting materials to obtain high performance in organic thin-film photovoltaic devices. A 1,4-bis(dimethylphenylsilylmethyl)[60]fullerene gives higher open circuit voltage than 1,2-diadduct because of smaller π-conjugated systems, and enables columnar fullerene-core array for high electron mobility and thermal crystallization for ideal phase separation with electron-donor materials. A 56π-electron fullerene derivative possessing the dihydromethano group as the smallest carbon addend does not disrupt fullerene-fullerene contact in solid state, giving high open-circuit voltage without decreasing of short-circuit current density and fill factor.

Poly(acrylonitrile) fibers are used in the manufacture of activated carbon fibers, which are activated with phosphate groups for the removal of lead ions in aqueous solutions. Removal of lead ions is performed in a water bath at 30°C. Trough isotherm models of Langmuir and Freundlich analyzed the aqueous solution. Kinetic analysis is performed using the model pseudo-first and pseudo-second order. The result show that adsorption equilibrium is adjusted to the Freundlich model and the kinetic model of pseudo-second order led to the best fit correlation.

In this study, we propose copper oxide (CuOx) edge-termination for GaN-based Schottky barrier diodes (SBDs) with low turn-on voltage. CuOx fabricated by thermal oxidization of sputtered Cu film at 275°C consisted mainly of Cu2O which is known as a p-type semiconductor. We applied CuOx edge-termination to GaN SBDs with tantalum (Ta) Schottky electrode which has low work function of 4.25 eV. The experimental results of current-voltage characteristics insisted that CuOx edge-termination structure was effective to increase breakdown voltage of GaN SBDs with keeping low turn-on voltage of 0.29 V at 10 A/cm2.

This study presents an effort to couple a wafer removal rate profile model based on the locally relevant Preston equation to the change in pad thickness profile which reflects to post polish profile of the wafers after Chemical Mechanical Planarization. The result is a dynamic predictor of how the wafer removal rate profile shifts as the pad ages. These predictions can be used to fine tune the conditioner operating characteristics without having to carry out high cost and time consuming experiments. The accuracy of the predictions is demonstrated by individual confirmation experiments in addition to the evaluation of the defectivity performance with the varied pad conditioning profiles.

Direct ultrasonic vibration (DUV) method by dipping the horn into the melt can be used to make semi-solid metal slurry, but application of this process is embarrassed because of the erosion problem of titanium-alloy horn by aluminum melt. In order to avoid this problem, a slurry-making process with indirect ultrasonic vibration (IUV), in which the horn is vibrated under the outside of the metallic cup containing alloy melt, has been developed in this research. Semisolid slurry of A356 Al alloy was prepared by this process, and the effects of IUV treatment time on the morphology of the primary α-Al phase and mechanical properties of rheo-diecasting samples were studied. The results indicate that excellent semisolid slurry of A356 Al alloy could be obtained within 50s by applying IUV near its liquidus temperature, and the average diameter and shape coefficient of the primary α-Al particles were 75μm and 0.62, respectively. IUV treatment time had a significant effect on the mechanical properties of the rheo-diecasting samples, and samples treated by IUV for 50s had the maximum tensile strength and elongation. The maximum as-cast tensile strength and elongation were 244MPa and 7.5% respectively, which were increased by 10% and 75% respectively compared to conventional molten-melt die-casting samples. In addition, the mechanism of preparing semisolid slurry of A356 Al alloy by IUV is discussed.

In development of new explosives, it is often necessary to balance a number of attributes in performance while certain formulation constraints exist. Statistical design of experiments (DOE) is a valuable tool for rapid formulation optimization and minimization of costly and hazardous testing. During the development of metal-loaded explosives designed for enhanced blast, it was discovered that upon proper formulation, aluminum additives obtained full reaction by 7 volume expansions, which resulted in extremely high Gurney energies equivalent to LX-14 and PBXN-5 but with lower loading of nitramines. The early aluminum oxidation can be described by Eigenvalue type detonations, where the fully reacted Hugoniot of the condensed phase aluminum oxide and explosive products lies below the unreacted aluminum Hugoniot. Such an analysis describes fully the agreement of aluminum consumption by 7 volume expansions from 1-inch copper cylinder expansion tests and an analytic cylinder model, as well as detonation calorimetry. With the early reaction of aluminum also comes a shift in the gaseous reaction products to higher enthalpy species such as CO and H2, leading to further augmentation of blast. Thus, both the mechanical energy (for fragmentation or “metal pushing”) and blast (for structural targets) are available in a single explosive fill. This provides capability for combined metal pushing and blast in a single explosive that was not previously possible. Development of such explosives and the importance of modern statistical design of experiments will be shared.

Toward complete artificial photosynthesis systems to generate hydrogen andoxygen using visible light and water, we firstly design and fabricateoxygen-generating gel systems using the electrostatic interactions of ionicfunctional groups and steric effects of a polymer network. By using a graftpolymer chain with Ru(bpy)32+ units as sensitizers to closely arrange RuO2nanoparticles as catalyst, the functional groups transmit multiple electronscooperatively to generate oxygen. In this study, a novel strategy is shownto design a hierarchical network structure using colloidal nanoparticles andmacromonomers.

Coronary artery disease is a major problem worldwide causing 7.2 million deaths worldwide annually, resulting from vascular occlusion, myocardial infarction and its complications. Stent implantation is a percutaneous interventional procedure that mitigates vessel stenosis, providing mechanical support within the artery. However, stenting causes physical damage to the arterial wall. It is well accepted that a valuable route to reduce in-stent re-stenosis can be based on promoting cell response to nano-structured stainless steel (SS) surfaces such as, for example, by patterning nano-pits in SS. In this regard patterning by Focussed Ion-Beam (FIB) milling offers several advantages for flexible prototyping (i) practically any substrate material that is able to withstand high vacuum conditions of the microscope chamber can be used, (ii) there is high flexibility in the obtainable shapes and geometries by modulating the ion beam current and the patterning conditions, (iii) reduced complexity of the pattering process e.g. it is a single-step process with a possibility of real-time monitoring of the milling progression. On the other hand FIB patterning of polycrystalline metals is greatly influenced by channelling effects and re-deposition. Correlative microscopy methods present an opportunity to study such effects comprehensively and derive structure-property understanding that is important for developing improved pattering. In this report we present a FIB patterning protocol for nano-structuring features (concaves) ordered in rectangular arrays on pre-polished 316L Stainless Steel (SS) surfaces. An investigation based on correlative microscopy approach of the size, shape and depth of the developed arrays in relation to the crystal orientation of the underlying SS domains, is presented. The correlative microscopy protocol is based on cross-correlation of top-view Scanning Electron Microscopy (SEM), Electron Backscattered Diffraction (EBSD), and Atomic Force Microscopy (AFM).Various dose tests were performed, aiming at improved productivity by preserving nano-size accuracy of the patterned process. The optimal FIB patterning conditions for achieving reasonably high throughput (patterned rate of about 0.03 mm2 per hour) and nano-size accuracy in dimensions and shapes of the features, are discussed as well.

Two methods to create biomimetic anti-reflection nanostructures in ordinary glass microscope object slides are presented. One technique is based on a nanosphere lithography process combined with physical vapour deposition of nickel and reactive ion etching (RIE). The other uses plasma induced dewetting of a smooth nickel surface. The amount of reflected light was measured and a method to simulate the reflectivity from an atomic force microscopy (AFM) topography scan of the glass surface is presented. The reflectivity for visible light at normal incidence was reduced to 20-50 % of the original value with both methods and the simulation gives results in good agreement to the measurement.

Poly(N-isopropylacrylamide) (PNIPAM), a classic thermo-sensitive polymer,has a lower critical solution temperature (LCST) at ∼32°C. In this work wehave used molecular dynamics simulations to understand the origin of theLCST and agglomeration of PNIPAM chains of 5 and 30 monomer units (5-mer and30-mer). Experimentally, when the concentration of PNIPAM is >1 ppm,polymer chains after undergoing coil-to-globule transition above the LCSTaggregates to yield a stable colloidal dispersion.In our study two PNIPAMchains, consisting of 30 monomer units each, were placed in a cubicsimulation cell and were subsequently solvated. Simulations were carried outbelow and above the LCST, namely at 278 and 310K for 10ns. Simulatedtrajectories were analyzed for structural and dynamical properties of bothPNIPAM and water. We observe coil-to-globule transition in PNIPAM above theLCST. We also find that the PNIPAM chains agglomerate above the LCST. Wealso observe entanglement in PNIPAM chains below the LCST. We also studyagglomeration of 5 PNIPAM chains each consisting of 5 monomer units. Therewas no significant difference in polymer agglomeration behavior across theLCST for these short chain oligomers. The agglomeration behavior is thusstrongly correlated to the size of the polymer chains. These results providefundamental insight into the atomistic scale mechanism of PNIPAMagglomeration across the LCST.