Platinum (Pt) nanoparticles were synthesized on tin dioxide (SnO2) nanowires by applying γ-ray radiolysis. The growth behavior of Pt nanoparticles was systematically investigated as a function of precursor concentration, illumination intensity and exposure time of the γ-rays. We found that these processing parameters greatly influenced the growth behavior of Pt nanoparticles in terms of size and formation density. Vapor-phase-grown SnO2 nanowires were uniformly covered with Pt nanoparticles by the radiolysis process. The Pt nanoparticle-functionalized SnO2 nanowires were tested as sensors for detecting reductive gases including carbon monoxide, toluene, and benzene. The results indicate that the γ-ray radiolysis is an efficient way of functionalizing the surface of oxide nanowires with catalytic Pt nanoparticles.

In spite of previous reports documented that many beneficial effects can be obtained by adding rare earth (RE) elements to Pb-free solders, this paper presents the risk of Sn whisker growth in the Sn–9Zn–0.5Ga Pb-free solders due to the addition of RE Pr. Results showed that solder microstructures are refined with the addition of trace amount of Pr. However, excessive Pr addition led to the formation of Pr–Sn intermetallic compounds (IMCs) and spontaneous growth of Sn whiskers on the IMC surfaces. It was found that the IMC size has a dramatic impact on whisker growth. Sn whiskers grew in slow-cooled solder with larger IMC particles are much longer and more prolific than that in fast-cooled solder with smaller IMC size. It was proposed that the driving force for whisker growth is originated from the oxidation of the RE-rich Pr–Sn IMCs. Our results indicated that the effects of RE on Pb-free solders should be reevaluated.

Hybrid ultrahigh molecular weight polyethylene–nylon 6–single-wall carbon nanotube fibers were processed using solution spinning method. Elastic properties and normalized velocity ($\root 3 \of \Omega $) of the hybrid fibers were measured before and after strain hardening through repeated loading–unloading cycles. Phenomenal improvement in the properties was found: strength, modulus, and normalizing velocity increased by almost one order of magnitude after strain hardening. Neat and reinforced filaments were characterized through differential scanning calorimetry, Raman spectroscopy, and scanning electron microscope before and after strain hardening. It has been revealed that nylon 6 contributed to the deformation ability of the composite fiber, while carbon nanotubes contributed to the sharing of load as they aligned during extrusion and strain hardening processes. Important morphological features determining the fiber properties were the change in crystallinity and rate of crystallization, formation of microdroplets, interfacial sliding, polymer coating of nanotubes, alignment of polymer fibrils and nanotubes.

We investigated the conductivity of high-density bulk-anatase samples with a grain size between 24 and 56 nm prepared by high pressure field-assisted sintering. When exposed to humid atmosphere, the insurgence of proton conductivity was observed for temperatures below 350 °C. Below this temperature, the samples showed a conductivity several orders of magnitude higher than that measured under dry oxygen atmosphere. The protonic conductivity strongly increased as grain size decreased, while a negligible dependence from porosity was observed when the latter ranged between 8 and 25 vol%. If compared with zirconia- and ceria-based nanomaterials with similar grain size, bulk nanometric anatase showed the highest low temperature protonic conductivity as well as the highest crossover temperature between dry and humid conduction behavior.

Control of the electrical properties of ZnO is difficult to achieve. Doping is affected by the presence of a n-type background. Magnetotransport measurements can extract detailed information on donors and acceptors, but characterization is complicated by effects such as the surface conductivity. This conducting layer can be activated by ambient illumination or by heating in the absence of oxygen. There are considerable differences in the behavior of the various polar and nonpolar crystal faces. This paper provides an overview of the properties of ZnO surface conductivity, as well as the methods which have been implemented to account for it while interpreting carrier transport measurements.

The mechanical properties of submicron scale columnar zinc structures, with average diameters between 130 and 1060 nm, were characterized by uniaxial microcompression tests. The zinc pillars were fabricated by electron beam lithography and electroplating and were found to be generally single crystalline, with a preferred out-of-plane orientation close to the [0001] directions. Post deformation microstructural analysis suggests that the zinc pillars maintain their single-crystalline structure, but without twin boundary formation. Interestingly, the engineering flow stress results indicate that small-scale zinc structures are insensitive to both strain rate and size.

The whiskers spontaneously grown in Cd–Mg–Yb alloy containing icosahedral quasicrystal as dominant phase have been investigated by electron microscopy. It is found that: (i) the whiskers are mainly composed of Cd with growth direction along . CdO particles are frequently observed on surfaces of whiskers and the alloy, indicating the importance of the oxidation process during the whisker growth; (ii) there exist four types of orientation relationship between Cd and CdO. The interfaces between them are shown to accommodate large lattice misfit, which is well explained by near coincidence site lattice model; (iii) nanosized Cd particles are observed to aggregate around the whisker root, providing a convincing experimental evidence for the long-range atomic diffusion. Our study offers a unique opportunity to unveil the relationship between unstability of quasicrystal structure and whisker formation and may have some implications for oxidation process of metals.

Electrical conductivity and magnetic properties of core-shell silver-coated magnetite composite nanoparticles prepared by electroless deposition of silver on magnetite nanopowder are found to be affected mainly by the pressure used when preparing the nanoparticles sample cylinder and the Ag content in the nanoparticles. The electrical conductivity can be enhanced by increases of both the pressure and the Ag content. Direct current volume electrical resistivity of the nanoparticles with 40 wt% silver content is close to the order of 10−4 Ω cm when the pressure is larger than 1 × 106 Pa. The saturation magnetization of the nanoparticles almost reduces linearly with increasing the silver content. According to the rule of mixtures, the resistivity of the nanoparticles is calculated. But it shows that the calculated values have a large deviation with the corresponding measured ones. As a comparison, resistivity and saturation magnetization of the mixtures consisting of silver and magnetite nanopowder are also measured. It will be an effective method to adjust the electromagnetic properties of the nanoparticles by changing the silver content.

Thin-film transistors (TFTs) utilizing a TiZnSnO (TZTO) channel layer were fabricated by using a solution process. The effect of annealing temperature on the device performance of the TZTO TFTs was investigated. TFTs with nanocrystalline TZTO films exhibited a better device performance than those with amorphous TZTO films. The on/off current ratio of the TZTO TFTs annealed at 600 °C was as large as 4.2 × 106. The field-effect mobility (μFE) of 4.1 cm2/Vs and subthreshold swing of 1.2 V/decade were achieved.

Carbide precipitation within low carbon AISI H13 hot work tool steel that had either been quenched at 80 °C or cryogenically treated at −196 °C prior to tempering has been examined using micrometer-scale synchrotron diffraction mapping. Vanadium-rich cubic M8C7 carbide, lattice parameter of approximately 0.8610 nm, not identifiable using laboratory powder x-ray diffraction (PXRD), was found to be present in all samples. The concentration of this phase was greatest in the rapidly cooled cryogenically treated sample. However, all cryogenic treatments resulted in greater carbide concentrations than in the quenched sample. In addition rapid cryogenic cooling by immersion in liquid nitrogen (N2), as compared with slow cooling to −196 °C over a 3 h duration, results in greater order within the carbide phase subsequent to tempering, as interpreted by analysis of unit cell size variation, and the smallest stress, as interpreted by diffraction peak full width half maximum height distributions.

Oxide semiconductors exhibit a range of physical properties and have potential optical, electronic, and energy applications. Transparent conducting oxides (TCOs) are currently used in products such as flat-panel displays. The prevailing n-type conductivity in these materials has historically been attributed to native defects such as oxygen vacancies. Recent calculations and experiments, however, have provided evidence that native defects are actually not responsible in majority of the cases. Hydrogen, on the other hand, does act as a shallow donor and can dramatically affect the electrical properties of oxides. In addition to contributing to n-type doping, hydrogen also passivates dangling bonds in cation vacancies and passivates acceptor dopants. Some oxides contain “hidden hydrogen,” perhaps H2 molecules, which dissociate at elevated temperatures. In this article, the many roles of hydrogen in zinc oxide, tin dioxide, titanium dioxide, indium (III) oxide, gallium (III) oxide, and strontium titanate are reviewed. The emphasis is on fundamental electronic, structural, and vibrational properties of hydrogen complexes, as determined by experiment and theory.

Nanofibers (NFs) of Ga-doped ZnO (GZO) were prepared by electrospinning of polymer–salts solution. Sintering profiles reported in the literature led to loss of the fibrous structure. Hence, the morphology, thermal stability, and phase composition of green and sintered fibers were investigated as function of sintering conditions to elucidate this degradation process. Optimal results were obtained at 400 °C for 30 min. This low temperature sintering of GZO fibers has not been previously reported. The fibers were porous with a significant surface area, making it possible to test their sensitivity to environmental changes. In particular, the response of the GZO NFs to changes in humidity was demonstrated for the first time. The electrical and sensing properties of single NFs prepared at these conditions were studied using a field-effect transistor mode.

Zinc oxide-based transparent amorphous oxide semiconductors (TAOS) are strong contenders to replace amorphous and polycrystalline silicon for large area display backplanes due to their high electron mobility. To enable future roll-to-roll printed electronics, solution-processed fabrication methods are needed. Here, we use low-temperature measurements from 77 to 300 K to quantitatively compare charge transport mechanisms and band-tail density of states of solution-processed zinc tin oxide (ZTO) thin film transistors fabricated with different film composition and annealing temperature. The devices exhibit percolation conduction with Fermi level pinning at high charge carrier concentrations. The shape and energy levels of band-tail states can be engineered by process and stoichiometry. For optimal amorphous ZTO film with Zn:Sn ink ratio of 7:3 and annealing temperature of 480 °C, the band structure exhibits Arrhenius and percolation energy values of 7 and 3 meV, respectively, better than those measured by others for vacuum-processed TAOS films, showing the potential of solution processing.

This work presents key modeling aspects that are central to the manipulation of the decoration of metallic nanoparticles by a thin shell of a metal of different chemical nature. The concept of underpotential deposition is generalized to nanoparticles. An all-atom model, taking into account many-body interactions by means of the embedded atom potential, was used to represent nanoparticles of different sizes and atomic adsorbates on them. A full set of state-of-the-art computer simulations are performed for a model system, showing that selective decoration of facets is possible. The trends observed in the present work are in good qualitative agreement with experimental data reported very recently.

Large quasicrystals up to ∼10 μm in size with a volume fraction of ∼30% have been identified in a nitrogen gas-atomized marginal glass-forming alloy Al85Ni5Y6Co2Fe2 by detailed transmission electron microscopy. The formation of the large quasicrystal (Q) phase is discussed through the configuration of the valence electrons of its constituent elements, and the thermodynamic and kinetic factors associated with the solidification of this marginal glass-forming alloy during gas atomization. The finding leads to an important inference that marginal glass-forming alloys could be ideal systems for the formation of bulk quasicrystals under appropriate kinetic conditions. The Q phase is stable up to ∼500 °C and decomposes thereafter. The activation energy for the decomposition of the Q phase is similar to the self-diffusion of Al. Two new intermetallic phases associated with the formation and decomposition of the Q phase have also been identified and characterized.

Multiwalled carbon nanotubes/Pd nanoparticles (CNT/Pd) were prepared by different four synthesis techniques. After the chemical oxidation of CNTs, the infrared absorption data indicated the existence of several functional groups loaded on the CNTs surfaces. The first Pd deposition technique went through the processes of Sn sensitization and Pd deposition on the functionalized surfaces of CNTs. The second method was Pd deposition by polyol process. The third method was Pd deposition using hydrazine in acidic media. In the fourth method, fourth generation poly(amidoamine) dendrimer and sodium borohydride were used as an intermediator between Pd and the surfaces of CNTs and as a reducing agent of the palladium chloride, respectively. It was observed from transmission electron microscope analysis of the produced CNT/Pd nanoparticles that the Pd particles on the CNTs prepared by the fourth method had the smallest average particle size of 3 nm. The Pd contents in the produced CNT/Pd nanocomposite powders were determined by thermogravimetric analysis.

The fabrication of capillary cylindrical crystals from colloidal suspension with controllable thickness by evaporation-induced self-assembly method has been investigated. The thickness of the hollow cylinders can be precisely controlled ranging from monolayer to tens of layers by varying the suspension concentration. With the increase of suspension concentration, the particles fill completely inside capillaries to form solid bulk crystals and the critical values are found in capillaries with various diameters. Scanning electron microscope images confirm the face-centered-cubic structure in both crystals, but with two different [111] crystalline directions. The experiment parameters, such as the solvent, concentration of the suspension and inner diameter of capillary are studied for the quality and the number of film layers control. Qualitative analysis has been performed to probe into the solvent evaporation modes and the mechanism of particle arrangement inside the capillary.

In this article, the sol-gel methodology was used for coating an acrylonitrile butadiene styrene (ABS) polymer prepared by the rapid prototyping technology with a colloid containing the europium III dipicolinic complex, which presents high emission when excited in the ultraviolet region. Either acid or base was used for treatment of the ABS polymer, with a view to activating its surface. The thermal analysis evidenced a residual mass after 600 °C, which indicated that the coating adhered to the substrate. X-ray diffraction analysis showed that the structure of the ABS polymer was not affected by the sol-gel treatment. The large band centered at 287 nm, ascribed to ligand-metal charge transfer, can be used to excite the europium III dipicolinic complex in the ultraviolet C and ultraviolet B regions. The emission appears in the characteristic red region of the electromagnetic spectrum. These results indicate that the obtained material is a candidate for use as ultraviolet sensor.