A technique for simultaneous size and shape control of compound semiconductor nanostructures using poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) block copolymer/water/p-xylene lyotropic liquid crystals as templates is reported. Luminescent quantum dots of ZnSe were grown in the spherical domains of reverse (water-in-oil) cubic liquid crystals, hollow nanospheres and hollow nanotubes were grown around the dispersed spherical and cylindrical oil domains of the normal (oil-in-water) cubic and hexagonal phases respectively, and free-standing quantum wells (nanoplates or nanolaminates) were grown in the lamellar liquid crystals. The ZnSe nuclei were formed at room temperature by a spontaneous and irreversible reaction between zinc acetate that was dissolved in the water phase, and hydrogen selenide that was allowed to diffuse into the liquid crystalline templates. The nanostructures were characterized by HR-TEM, XRD, and optical spectroscopy. The shape of the nanocrystals can be controlled by selecting the structure of the templating phase. The size of the nanocrystals can be controlled by the size of the nanodomains and the concentration of the zinc precursor in them.

Zinc Oxide (ZnO) is a II-VI semiconductor material with a wide direct band-gap of 3.37 eV at room temperature (RT). In the past decades, the material has been used for a variety of applications such as gas sensors, surface acoustic wave devices, or transparent contacts. Recently, ZnO has gained a new substantial interest primarily because to its potentialities for optoelectronic and spintronic applications. The renewed interest has been fueled by the availability of high-quality bulk substrates, reports of p-type conduction and theoretical predictions of its ferromagnetic behavior at room temperature when doped with transition metals. In the domain of optoelectronics, its main applications include devices emitting in the blue and UV regions by exploiting its wide band-gap such as light-emitting and laser diodes. With respect to several wide band-gap semiconductor materials, ZnO has the advantage of a larger exciton binding energy (about 60 meV) which paves the way for an intense near-band-edge excitonic emission at room and higher temperatures. On the other hand, a band gap engineering can be also achieved by the incorporation of Cadmium and Magnesium atoms into the ZnO lattice.

Many techniques have been used to prepare ZnO in various forms, such as single crystals, powders and films. In the past few years, the great attention toward materials with nanometric size have motivated a number of studies on the synthesis of ZnO nanocrystals. Ion implantation is one of the most effective and versatile technique to obtain nanoparticles. ZnO particles embedded in silica matrix have been successfully prepared by ion implantation followed by thermal oxidation.

In this work, we report on a detailed structural and optical characterization of the ZnO-silica nanocomposites by using several complementary techniques; in particular, Glancing Incidence X-ray Diffraction (GIXRD), Rutherford Backscattering Spectrometry (RBS), linear Optical Absorption (OA) in the UV-near IR spectrum and Photo-Luminescence (PL). The ZnO nanoparticles embedded in SiO2 matrix were prepared by implanting the substrates with 130 keV Zn+ ions at doses of 1, 1.5 and 2´1017 ions/cm2. Subsequently, the implanted samples were annealed for 1h in a furnace at a temperature between 500 and 800°C under flowing O2 gas. X-ray diffraction results indicate the formation of Zn and ZnO nanoparticles in the as-implanted and annealed samples, respectively. Moreover, the ZnO nanocrystals embedded in the SiO2 matrix have a (002) preferred orientation. After the oxidation, the optical absorption spectra show an absorption edge at about 374 nm by confirming the presence of the ZnO particles. A relatively strong exciton photoluminescence peak was observed at room temperature under pulsed N2 laser excitation at l=337nm. The results obtained, peculiarly related to the implantation doses and annealing temperature, are discussed.

A surfactant-assisted co-precipitation method was employed for obtaining high surface area Ni-SDC with improved structural properties for SOFC applications. In the work, a cationic surfactant, cetyltrimethylammonium bromide(CTAB) was employed with NiCl2, SmCl3 and CeCl3 as precursors and NH4OH as mineralizer. The elimination of surfactants upon calcination gives rise to the formation of high surface area NiO-SDC. When calcined at 600°C, the powders with surface area of 249 m2/g, were obtained and the pore size was 14.45 nm. The powders consist of two phases, the cubic NiO and SDC confirmed with X-ray diffraction identification.

The reversible formation of aggregates in a shear thickening, concentrated colloidal suspension is investigated through speckle visibility spectroscopy, a dynamic light scattering technique recently introduced [1]. Formation of particle aggregates is observed in the jamming regime, and their relaxation after shear cessation is monitored as a function of the applied shear stress. The aggregate relaxation time increases when a larger stress is applied. Several phenomena have been proposed to interpret this behavior: an increase of the aggregate size, or a closer packing of the particles in the aggregates.

1. P.K. Dixon, D.J. Durian, Phys. Rev. Lett. 90, 184302 (2003).

Although Glassy Polymeric Carbon (GPC) is ideally suited for implants in the blood stream, tissue that normally forms around the moving parts of a GPC heart valve. There is concern that the tissue lose adhesion and create the condition for embolisms downstream. We have shown that silver ion implantation or argon ion assisted surface deposition of silver inhibits cell growth on GPC, a desirable improvement of current cardiac implants. In vitro biocompatibility tests have been carried out with model cell lines to demonstrate that near surface implantation of silver in GPC can completely inhibit cell attachment on implanted areas while leaving adjacent areas unaffected. Patterned ion implantation permits precise control of tissue growth on medical applications of GPC.

III-V semiconductor nanocrystals are of considerable interest due to their extensive applications in the optoelectronic and biomedical fields. In order to meet the practical use, the convenient and scalable production of III-V narrow-disperse nanocrystals is inspiring. We report an efficient and rapid method of preparing highly monodisperse InP nanocrystals using a wet-chemical redox synthetic approach with a noncoordinating solvent, employing organic reducing agent LiBH(CH2CH3)3 and yellow phosphor. As advantages of this approach, reaction temperature is relatively low (80°C-120°C) and reaction time is less than 2 hours. Our characterization shows that the photoluminescence properties of InP nanocrystals are highly dependent on the particle size.

A simple novel route to synthesize aqueous tantalum and niobium precursors has been developed using cheap and stable Nb2O5 or Ta2O5 as starting source, based on basic flux technique. Various analytical techniques have been employed to characterize the purity, and thermal decomposition features of the precursors. Using home-made Ta and Nb precursors, several photocatalysts and ferroelectric powders such as LiNbO3, LiTaO3, Sr0.75Ba0.25Nb2O6, and SrBi2Ta2O9 have been prepared at lower processing temperature by a polymerizable complex route successfully.

Polydiacetylene (PDA) is a conjugated polymer that changes its fluorescent state in response to environmental changes and can act as a transducer to convert molecular interactions into a discernable output measurable in the macroscopic world. Energy transfer to fluorophores can further enhance the fluorescent signal. Diacetylene liposomes can be prepared with phospholipids and other cell membrane components in the liposomes, and photopolymerized. PDA liposomes have been used for absorbance based detection of biological targets; however, moving to fluorescence detection gives increased sensitivity and also allows sensing from PDA structures deposited on opaque membranes. Unfortunately, PDA liposomes are prone to aggregation, particularly in the presence of divalent cations. Many enzymes require divalent cations such as Mg2+, Mn2+, Ca2+, etc., as co-factors; the tendency of PDA liposomes to aggregate in the presence of these cations limits their use as a platform for detection of enzymatic activity. We have developed methods for attaching PDA liposomes to glass fiber membranes, via thiol-epoxide coupling chemistry, for use in bio-assays and have seen that these materials can be used in place of PDA liposome solutions. We present here the attachment of PDA liposomes to glass fiber membranes in 96-well format, cryogenic TEM scans of the attached liposomes and the use of these materials in fluorescence assays to detect the activity and inhibition of phospholipase A2.

In this research, sodium dodecyl sulfates (SDS) and N-cetyl-n,n,n-trimethyammonium bromide (CTAB) surfactant solutions are used as solvents of polystyrene (PS) colloidal suspension during the fabrication of colloidal crystals. The effects of the surfactant on the quality and the morphology of the colloidal crystals are studied. It was found that surfactants not only change the charge of PS colloidal particles, but also significantly changed the surface tension and the 3 phase contact angle of the suspension with respect to the glass substrate, in turn they change the thickness of the formed crystal as well as the crystal structure. The derived knowledge will be potentially useful in clarifying the mechanisms involved in the formation of colloidal crystals.

Atomic Force Microscopy (AFM) was employed to probe the mechanical properties of surface-charged polymethylmethacrylate (PMMA)-based terpolymer and a composite terpolymer core-silica shell nanosphere in air and water media. Since these materials exhibit enhanced mechanical properties, such as toughness and elasticity, and enhanced chemical stability, they are particularly interesting for potential applications in reducing defectivity during the process of Chemical Mechanical Planarization. The polymer particles were subjected to a thermal treatment aimed at improving their mechanical properties in terms of hardness (H) and elastic modulus (E). By analysis of force-displacement curves and on the basis of Hertz's theory of contact mechanics, Young's moduli were measured for the terpolymer compared with the composite that has expected mechanical property enhancement due to its silica shell. In air, E increases from 4.3 GPa to 6.6 GPa for the treated terpolymer compared with the respective value of 10.3 GPa measured for the composite. In water, E increases from 1.6 GPa to 4.5 GPa for the thermally treated terpolymer that is comparable with the respective value of 3.6 GPa measured for the composite. This observation suggests that as an alternative to the creation of polymer-silica composite nanoparticles for CMP, comparable mechanical properties can be achieved by a simple heat treatment step.

ZnTe quantum dots (QDs) have been very attractive because of their potential applications in optoelectronic devices operating in the blue-green region of the spectrum. This paper describes a convenient one-step synthesis of high-quality ZnTe QDs in high-temperature organic solution with high yield. Anhydrous zinc chloride was dissolved in phenyl ether under argon protection and oleic amine was used as coordinating agent. Complex solution of metal tellurium in trioctylphosphine (TOP) was injected into the hot reaction mixture as a source of tellurium. The reaction was complete in several minutes and the resulting QDs were isolated by centrifugation and re-dispersed in hexane. The produced spherical ZnTe QDs are monodispersed and their sizes could be controlled simply by varying the growth temperature. The morphology and phase structure were investigated using TEM and XRD. Photoluminescence (PL) spectra were also studied and quantum size effects were observed as well.

The interaction forces between poly(N-isopropylacrylamide) (PNIPAAm)-grafted surfaces and colloidal particles in an aqueous solution were investigated using an atomic force microscope (AFM). Measurements were conducted between a smooth silicon wafer on which PNIPAAm was terminally grafted and silica particles hydrophobized with a silanating reagent in an aqueous electrolyte solution under controlled temperature. Below the lower critical solution temperature (LCST) of PNIPAAm, there were large repulsive forces between the surfaces, while attractive forces were observed above LCST. When surface hydrophobicity of the particles increased, the magnitude of attractive force tended to increase. The changes of hydration state of the grafted PNIPAAm chains depending on temperature is considered to greatly alter the interaction force properties. The role of the intermolecular interaction between the PNIPAAm chains and the hydrophobic particles in the interaction forces is discussed.

Micro-scale to nano-scale carbon nitride (CN) particles were prepared by using plasma sputtering deposition technique. The preferred orientation of nanoscale CN particle distributions was obtained. Particles have been examined by using both Scanning Electron Microscopy (SEM) and Raman scattering (RS) spectroscopy. Setting bias voltage up to 5 kV, plasma-sputtering deposition gave rise to several ring (diameters: 2.4, 3.2, and 4.4 mm) patterns of particle distributions where many small groups of nanoscale particles were observed. Each group of these particles appeared in a sunflower type of distribution, in which the biggest (85 nm) particle at the center was surrounded by many small sizes (30 nm) of CN particles. Disk type of the particles with a diameter of 10 μm was also observed at different experimental conditions. Typical G, D bands and C=N band in the Raman spectra of the samples were identified. The intensity of the D bands obviously varied at the different deposition conditions.

Microbial synthesis of gold nanoparticles was achieved at 25°C and pH 7-1 using the mesophilic bacterium Shewanella algae with H2 as the electron donor. The microbial synthesis of gold nanoparticle was a fast process: 1 mM AuCl4− ions were completely reduced to insoluble gold within 30 min. At the solution pH 7, the gold nanoparticles of 10-20 nm were synthesized in the periplasmic space of S. algae cells. When the solution pH was decreased to 1, the gold nanoparticles of 50-500 nm were precipitated extracellularly. The solution pH was an important factor in controlling the morphology of biogenic gold particles and location of gold deposition.

We report the development of a metallic colloid sintering process enabling the creation of bonding layers at moderate temperatures ranging from 150°C to 300°C, and pressures lower than 5MPa. This colloidal n-propyl acetate dispersion of Ag nanoparticles, having an average size distribution of 103nm, was used in sintered interconnect fabrication. Open air sintering of a 10um thick film resulted in an average resistivity of 0.20·10−6 −0.30·10−6 Ωm. Film resistances were found to be as low as 0.18·10−6 Ωm. Independent test varying either pressure or temperature were correlated to ultimate shear strength and modulus. The analysis of a 1cm2 bond area resulted in a peak shear strength of 5.83 MPa and shear modulus of 346 MPa which occurred following bonding at 300°C with a pressure of 4.219 MPa.

Synthesis and functionalization of nanoparticles of yttrium vanadate doped with europium is described. Synthesis of yttrium vanadate leads to ovoid nanoparticles, with an average size of 24 nm. These nanoparticles are unstable in water, and surface charge can be brought by silicate, as proven by PCS, Zetametry and IR analyses. The nanoparticle surface is then functionalized with glycidoxypropyltrimethoxysilane. The rafting is characterized by 29Si MAS NMR, and ThermoGravimetric Analyses. This alkoxysilane presents an epoxy function which can then react with a nucleophilic molecule. The functionalization is studied by 29Si MAS NMR and TGA, whereas opening of the epoxy ring is studied by 13C MAS NMR. As an example of further reactivity, we chose to graft on the nanoparticles the active part of saxitoxin, a guanidinium group. This last functionalization is proven by optical experiments performed on a cell in biological conditions.

Poly(methyl methacrylate)/MgAl layer double hydroxides (PMMA/MgAl LDH) nanocomposites were prepared by in situ free radical polymerization with the organic modified MgAl-K2 LDH in the methyl methacrylate monomer and initiator of benzoyl peroxide. The morphology of MgAl-K2 LDH and PMMA/MgAl-K2 LDH nanocomposites were investigated by transmission electron microscopy (TEM) and powder X-ray diffraction, indicated that the MgAl-K2 LDH were dispersed in PMMA matrix to form PMMA/MgAl-K2 LDH nanocomposites with heterogeneous morphology comprising both exfoliated and intercalated PMMA/MgAl-K2 LDH nanocomposites . The thermal and mechanical characterization were carried out by thermogravimetric analysis (TGA) ¡Bdifferential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The properties of PMMA/MgAl-K2 LDH nanocomposites exhibit the better thermal and mechanical properties.