Measurements on URu2-xRexSi2 single crystals indicate that substitution of Re for Ru in URu2Si2 reduces the transition temperature of the hidden order state and quickly destroys superconductivity. At intermediate Re concentrations, weak ferromagnetism emerges and non Fermi liquid (NFL) behavior is observed in the low-temperature specific heat and electrical resistivity. A scaled Arrott analysis of the magnetization indicates the onset of ferromagnetism at x =0.15, where the hidden order disappears, and that the quantum phase transition is associated with novel critical exponents.

We reported the aqueous chemical method to fabricate the well-aligned ZnO/Al2O3 core-shell nanorod arrays (NRAs). The shell is composed of α-Al2O3 nanocrystals in amorphous Al2O3 layers. The photoluminescence (PL) measurements showed that the enhancement of near-band-edge emission in ZnO NRAs arrays due to the addition of Al2O3 shell was observed. The Al2O3 shell layer resulting in flatband effect near ZnO surface leads to a stronger overlap of the wavefunctions of electrons and holes in the ZnO core, further enhancing the NBE emission.

The electronic structure of plutonium is studied within the density-functional theory (DFT) model. Key features of the electronic structure are correctly modeled and bonding, total energy, and electron density of states are all consistent with measure data, although the prediction of magnetism is not consistent with many observations. Here we analyze the contributions to the electronic structure arising from spin polarization, orbital polarization, and spin-orbit interaction. These effects give rise to spin and orbital moments that are of nearly equal magnitude, but anti-parallel, suggesting a magnetic-moment cancellation with a zero total moment. Quantifying the spin versus orbital effects on the bonding, total energy, and electron spectra it becomes clear that the spin polarization is much less important than the orbital correlations. Consequently, a restricted DFT approach with a non-spin polarized electronic structure can produce reasonable equation-of-state and electron spectra for δ-Pu when the orbital effects are accounted for. Hence, we present two non-magnetic models. One in which the spin moment is canceled by the orbital moment and another in which the spin moment (and therefore the orbital moment) is restricted to zero.

We report the fabrication and characterization of segmented element power generator modules of 16 x 16 thermoelectric elements consisting of 0.8 mm thick Bi2Te3 and 50 μm thick ErAs:(InGaAs)1-x(InAlAs)x with 0.6% ErAs by volume. Erbium Arsenide metallic nanoparticles are incorporated to create scattering centers for middle and long wavelength phonons, and to form local potential barriers for electron filtering. The thermoelectric properties of ErAs:(InGaAs)1-x(InAlAs)x were characterized in terms of electrical conductivity and Seebeck coefficient from 300 K up to 830 K. Generator modules of Bi2Te3 and ErAs:(InGaAs)1-x(InAlAs)x segmented elements were fabricated and an output power of 6.3 W was measured. 3D finite modeling shows that the performance of thermoelectric generator modules can further be enhanced by the improvement of the thermoelectric properties of the element materials, and reducing the electrical and thermal parasitic losses.

A theory is presented which describes the photoemission spectra of actinide compounds starting from the atomic limit of isolated actinide ions. The multiplets of the ion are calculated and an additional term is introduced to describe the interaction with the sea of conduction electrons. This leads to complex mixed-valent ground states, which describes well the rich spectrum observed for PuSe. In particular, the three-peak feature, which is often seen in Pu and Pu compounds in the vicinity of the Fermi level originates from f6 → f5 emission. The theory is further applied to PuSb, PuCoGa5 and Am.

In this study, we performed nanoindentation experiments on two sets of silicon nanolines (SiNLs) of widths 24 nm and 90 nm, respectively, to investigate the mechanical behavior of silicon structures at tens of nanometer scale. The high height-to-width aspect ratio (∼15) SiNLs were fabricated by an anisotropic wet etching (AWE) method, having straight and nearly atomically flat sidewalls. In the test, buckling instability was observed at a critical load, which was fully recoverable upon unloading. It was found that friction at the contact between the indenter and SiNLs played an important role in the buckling response. Based on a finite element model (FEM), the friction coefficient was estimated to be in a range of 0.02 to 0.05. The strain to failure was estimated to range from 3.8% for 90 nm lines to 7.5% for 24 nm lines.

With decreasing feature sizes for every technology node, multi-level metallization schemes that employ copper interconnects and low-k dielectrics are required to achieve the requisite circuit performance. Here, the effects of the mechanical stresses originating from the packaging process on Cu/Low-k interconnects are assessed. The impact of package defects on interconnect reliability is also analyzed. It is seen that the package reliability varies with underfill mechanical properties. The packaging process introduces global level stresses that propagate to the local, i.e. interconnect, level. Moreover, the package defects also have an adverse impact on the mechanical stresses in the metallization structure. The package defects alter the mechanical stresses in the metal lines and affect the reliability. The complex interaction between packaging process induced stresses, package level defects and mechanical properties of various materials is analyzed in order to create robust interconnect designs.

In our study, closed-core threading screw dislocations and micropipes were studied using synchrotron x-ray topography of various geometries. The Burgers vector magnitude of TSDs can be quantitatively determined from their dimensions in back-reflection x-ray topography, based on ray-tracing simulation and this has been verified by the images of elementary TSDs. Dislocation senses of closed-core threading screw dislocations and micropipes can be revealed by grazing-incidence x-ray topography. The threading screw dislocations can be converted into Frank partial dislocations on the basal planes and this has been confirmed by transmission synchrotron x-ray topography.

The microstructure in a Co-rich, Co-15 at.% Nb alloy was characterized in the as-cast condition. A predominantly lamellar eutectic morphology composed of a Co-Nb solid solution and the C15 Laves phase NbCo2 was confirmed by transmission electron microscopy. The C15 phase was heavily twinned, with only one variant of twins being present in the individual lamella, while the Co solid solution had the face centered cubic structure. In-situ heating to 600°C in the microscope confirmed the decomposition of the metastable Laves phase into a fine equiaxed, ˜10-20 nm grain size microstructure, and the product phase is the monoclinic Nb2Co7. The individual grains appear faulted. The matrix solid solution retained the fcc structure and no change in structure was observed on cooling to room temperature. Heating to temperatures as high as 1130°C leads to rapid grain growth in the Nb2Co7 phase, and the nucleation and growth of a few new grains within the original grains; however, the reverse peritectoid transformation previously reported, was not observed.

The performance of the devices of bulk heterojunction polymer-based solar cells were investigated by using poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61 butyric acid methyl ester (PCBM) as light absorption (viz. active) layer, with TiOx as interlayer as follows: ITO/PEDOT:PSS/P3HT-PCBM/TiOx/Al [1] through the treatment ofmicrowave irradiation (single mode of 2.45 GHz, 800 W for 1, 2.5, or 5 min).Such treatments enabled to increase the short-circuit current density J sc (from 4.53 mA cm−2 to 7.27 mA cm−2) and fill factor FF (from 0.41 to 0.66) of the cell, though the open circuit voltage V oc was decreased (from 0.61 V to 0.57 V) along the irradiation.Absorption spectra of P3HT-PCBM blended film before and after the microwave treatment were observed.Shoulders at 550 nm and 600 nm appeared after the irradiation.This result implies that the microcrystallization of P3HT was slightly promoted through the microwave treatment.

To meet increasingly challenging and complex systems requirements, it is not enough to use one single semiconductor technology but to integrate several high performance technologies in an efficient and cost effective way. Heterogeneous integration (HI) approaches lead to a significant higher design flexibility and performance. In this paper we present some of the HI approaches that are being used and developed at Northrop Grumman Space Technology (NGST) that include selective epitaxial growth, metamorphic growth and wafer level packaging (WLP) technology. More recently we are developing a scaled and selective wafer packaging technique to integrate III-V semiconductors with silicon under the COSMOS DARPA program.

Fibrous media in the form of nonwoven filters have been used extensively in water treatment as pre-filters or to support the medium that does the separation. Nonwoven media are composed of randomly oriented micron-size fibers and provide a one step separation as a substitute for conventional processes comprising chemical addition, flocculation, sedimentation, and sand filtration. At present the use of nonwoven filter media is limited to pre-filters and is not used further downstream as high performance filters. However it is expected that by reducing the fiber size in the nanometer range, higher filtration efficiency can be achieved. With the advent of nanotechnology, the ease of producing high quality nano scaled fibers is now a reality. Recent advancements in nanofibrous media through surface modifications have shown that nonwoven media can be used beyond the prefilter stage. Furthermore the pore size of the filter media can be controlled through modification of fiber size and thickness of membranes. These nanofibrous membranes possess high surface area and large porosity leading to high flux, low pressure membranes. This article highlights important opportunities and challenges associated with developing nanofibrous media for water treatment. In addition, we have attempted to capture a snapshot of this rapidly developing new area of fibrous media for water treatment for the benefit of the wider membrane community.

A novel Ce4+/Ce3+- V2+/V3+ redox flow cell has been investigated. It was composed of the Ce4+/Ce3+ couple, which replaced the V5+/V4+ couple of the all6vanadium redox flow cell, and the V2+/V3+ couple. The normal potential and the kinetic parameters for anodic oxidation of Ce3+ and cathodic reduction of Ce4+ were measured. The results showed that the surface of platinum electrode was fully covered with type I oxide that inhibited the reduction of Ce4+. The reversibility of the Ce4+/Ce3+ couple improved with the increase of H2SO4 concentration, but both higher energy efficiency and coulombic efficiency were observed in 0.5 mol/dm3 H2SO4 solution. Different electrochemically active substances were found to exist at various state of charge (SOC) and the reversibility of the Ce4+/Ce3+ couple at the carbon electrode was found to be superior to platinum electrode. Periodic charge6discharge measurements were conducted under constant current and constant load with the proposed Ce6V redox flow cell. The results indicated that the coulombic efficiency remained around 90% and the discharge voltage stabilized between 1.5 and 1.2 V. But as the cycle numbers increased, the discharge capacity declined a bit and a better result might be expected by improving the separator materials and increase the concentration of electro6active materials. By comparison with the existing Fe6Cr, Fe6Ti and all6vanadium redox flow cell, the Ce6V system has a higher open6circuit voltage (OCV). And results from this preliminary study suggest that the novel Ce6V redox flow cell is a promising energy storage system and is worthy of further studies.

We describe electrochemical synthesis of a bulk metamaterial, consisting of silver nanowires in Porous Anodic Alumina membrane and its characterization. We have found that the quality of the synthesized metamaterial depends on the metal used as a working electrode at the optimal conditions of the electroplating process. The dissolution of the thin layer of working electrode is occurred during the electrochemical reaction. It suggests an important role of interfacial phenomena taking place between the working electrode and the sample holder.

In this paper we present results on the optimization of device architectures for colour and imaging applications, using a device with a TCO/pinpi'n'/TCO configuration. A set of different devices with different intrinsic back layers are analysed.

The effect of the applied voltage on the color selectivity is discussed. Results show that the spectral response curves demonstrate rather good separation between the red, green and blue basic colors. Combining the information obtained under positive and negative applied bias a colour image is acquired without colour filters or pixel architecture. A low level image processing algorithm is used for the colour image reconstruction.

A low-cost alternative route for large-scale fabrication of high purity porous silicon car-bide is reported. This allows a three-dimensional arrangement of pores with adjustable pore di-ameters from several 10 nanometers to several microns. The growth of SiC is here based on a combined sol-gel and carbothermal reduction process. Therein tetraethoxysilane is used as the primary silicon and sucrose as the carbon source. We provide two different sol-gel based ways for preparation of porous SiC, obtaining either a regular porous or a random porous type. Regu-lar porous SiC with monodisperse ordered spherical pores of predefined size is obtained via liq-uid infiltration of a removable opal matrix. Whereas random porous material with polydisperse pores of an adjustable size distribution range, but without order, can be achieved via free gas phase growth. This is performed by degradation of granulated sol-gel prepared material inside a sealed reaction chamber, resulting in a SiO/CO/SiC rich gas atmosphere, which causes SiC growth inside the granulate itself. For both types doping of the initially semi-insulating porous SiC is possible either during the sol-gel preparation or via the gas phase during the following annealing procedure. As probing dopants we have used P, N, B and Al, which are well known from 'conventional' SiC. Composition and structure of the obtained material was investigated using scanning electron microscopy, X-ray diffraction, nuclear magnetic resonance and Fourier transform infrared spectroscopy.

Semiconducting or metallic nanocrystals embedded high-k films have been investigated. They showed promising nonvolatile memory characteristics, such as low leakage currents, large charge storage capacities, and long retention times. Reliability of four different kinds of nanocrystals, i.e., nc- Ru, -ITO, -Si and -ZnO, embedded Zr-doped HfO2 high-k dielectrics have been studied. All of them have higher relaxation currents than the non-embedded high-k film has. The decay rate of the relaxation current is in the order of nc-ZnO > nc-ITO > nc-Si > nc-Ru. When the relaxation currents of the nanocrystals embedded samples were fitted to the Curie-von Schweidler law, the n values were between 0.54 and 0.77, which are much lower than that of the non embedded high-k sample. The nanocrystals retain charges in two different states, i.e., deeply and loosely trapped. The ratio of these two types of charges was estimated. The charge storage capacity and holding strength are strongly influenced by the type of material of the embedded nanocrystals. The nc-ZnO embedded film holds trapped charges longer than other embedded films do. The ramp-relax result indicates that the breakdown of the embedded film came from the breakdown of the bulk high-k film. The type of nanocrystal material influences the breakdown strength.

Micromachined structures with diameters ranging from 50 — 100 μm have been applied to the measurement of the microscale shearing forces present at the wafer-pad interface during chemical mechanical polishing (CMP). The structures are 80 μm high poly-dimethyl-siloxane posts with bending stiffnesses ranging from 1.6 to 14 μN/μm. The structures were polished using a stiff, ungrooved pad and 3 wt% fumed silica slurry at relative velocities of approximately 0.5 m/s and downforces of approximately 1 psi. Observed lateral forces on the structures were on the order of 5–500 μN, and highly variable in time.

Worldwide, 1.2 billion people lack access to sufficient amounts of clean water, and 2.6 billion lack adequate sanitation. Also, industry relies on large quantities of water during manufacturing, which is then returned to the environment. Having adequate water supplies, and removing pathogens, chemicals, and other contaminants with high throughput at a low cost is a growing challenge around the world. This issue of MRS Bulletin examines how materials research, through the development of membranes, catalysts, nanoparticles, and other materials, is addressing these needs.

Recently, non-volatile polymer memories have been researched as a next generation of non-volatile memory because of its simple structure and easy fabrication process. We found that two types of non-volatile polymer memory have different I-V behavior. First Polymer non-volatile memory with metal / oxide / polymer / metal structure But Polymer non-volatile memory embedded Au Nano-crystal shows different I-V behavior. Polymer non-volatile memory shows NDR(Negative Differential Resistance) Region after threshold voltage and low to high current path at increasing positive and negative bias. We can observe NDR(Negative Differential Resistance) Region on Polymer non-volatile memory embedded Au Nano crystal. We fabricated devices three different type to confirm difference Polymer non-volatile memory with metal / polymer / metal structure, metal / oxide / polymer / metal structure and Au nano-crystal embedded Polymer non-volatile memory. First we fabricated Polymer non-volatile memory with metal / PVK(Poly-n-vinyl carbarzole) / metal structure. first type of device shows ohmic I-V behavior. Second type of polymer non-volatile memory has oxide layer between metal and polymer layer. Oxide layer made by O2 plasma treatment(100W RF power, 100SCCM O2 gas flow) after metal layer deposited. Second type of device has same structure as first device except oxide layer. Second type of device shows I-V behavior similar to Resistive Memory. Resistive non-volatile memory shows low to high current path at increasing positive bias and high to low current path at increasing negative bias. I-V behaviors of second device due to effect of oxide layer between metal and polymer layer. Third type of polymer non-volatile memory we embed Au nano-crystal layer in polymer layer. Au nano-crystal layer embedded by curing process. We deposit 5nm Au layer after spin coated PVK(Poly-n-vinyl carbarzole) layer and curing at 300¡É. We can observe NDR(Negative Differential Resistance) Region and different I-V behaviors with other type of device. Finally we fabricated polymer non-volatile memory embedded au nano-crystal by dispersion method to confirm effect of au nano-crystal. We report difference I-V behaviors polymer non-volatile memory with metal / polymer / metal structure and polymer non-volatile memory embedded au nano-crystals