On the basis of the Fe84.3C4.6Cr4.3Mo4.6V2.2 high-speed tool steel, manufactured under relatively high cooling rates and highly pure conditions, a further improvement of the mechanical characteristics by slight modification of the alloy composition was attempted. For this, the alloy Fe88.9Cr4.3V2.2C4.6 was generated by elimination of Mo. By applying special preparation conditions, a microstructure composed of martensite, retained austenite, and a fine network of special carbides was obtained already in the as-cast state. This material exhibits extremely high compression strength of over 5000 MPa combined with large compression strain of more than 25% due to deformation-induced martensite formation. With this alloy a new composition of transformation-induced plasticity-assisted steels was found, which shows an extreme mechanical loading capacity.

A simple and environmentally benign three-step hydrothermal method was developed for growing oriented single-crystalline TiO2-B and/or anatase TiO2 nanowire arrays on titanium foil over large areas. These nanowire arrays are suitable for use as the anode in lithium ion batteries; they exhibit specific capacities ranging from 200–250 mAh/g at charge-discharge rates of 0.3 C where 1 C is based on the theoretical capacity of 168 mAh/g. Batteries retain this capacity over as many as 200 charge-discharge cycles. Even at high charge-discharge rates of 0.9 C and 1.8 C, the specific capacities were 150 mAh/g and 120 mAh/g, respectively. These promising properties are attributed to both the nanometer size of the nanowires and their oriented alignment. The comparable electrochemical performance to existing technology, improved safety, and the ability to roll titanium foils into compact three-dimensional structures without additional substrates, binders, or additives suggest that these TiO2 nanowires on titanium foil are promising anode materials for large-scale energy storage.

A dye-sensitized photoelectrochemical (DS-PEC) cell consisting of SnO2 and ZnO nanoparticles was found to yield higher solar energy conversion efficiency than similar cells made of the individual oxide semiconductors when they were sensitized with an indoline dye. The SnO2/ZnO composite solar cell gave an overall energy conversion efficiency of 3.8% while the SnO2 and ZnO individual cells yielded efficiencies of 2.8% and 1.2%, respectively, under standard AM 1.5 irradiation (100 mW cm−2). The broadening of the absorption spectra and a large red shift of the absorption peak were observed by the adsorbing dyes on the composite film suggesting the formation of various kinds of J-aggregates. It is suggested that the formation of the J-aggregates and the presence of the ZnO barrier were responsible for the higher efficiency of the composite cell.

Fracture surfaces of Zr-based bulk metallic glasses of various compositions tested in the as-cast and annealed conditions were analyzed using scanning electron microscopy. The tougher samples have shown highly jagged patterns at the beginning stage of crack propagation, and the length and roughness of this jagged pattern correlate well with the measured fracture toughness values. These jagged patterns, the main source of energy dissipation in the sample, are attributed to the formation of shear bands inside the sample. This observation provides strong evidence of significant “plastic zone” screening at the crack tip.

Sub-10 nm monodispersed NaYF4:Eu/Ba nanocrystals were synthesized by a hydrothermal method. Under 396-nm excitation, in addition to the characteristic emissions of Eu3+ ions, an intense emission band originating from the d–f transition of the Eu2+ ions is also observed, indicating that Eu3+ and Eu2+ coexist in Eu/Ba-codoped NaYF4 nanocrystals. The dependence of the luminescence on the Ba2+ concentration was studied. Tunable photoluminescence of NaYF4:Eu nanocrystals was successfully achieved by codoping with Ba2+ ions. In addition, when the Ba/Ln ratio is 3:7 and 4:1, pure cubic Ba0.92Y2.15F8.29:Eu and tetragonal BaYF5:Eu nanocrystals were obtained, respectively.

Precipitation of ZrCu with the B2 structure in Zr50Cu50–xAlx (x = 0, 4, 6) metallic glasses by rapidly heating and cooling was investigated. By rapidly heating and cooling, the ZrCu B2 phase precipitates the most in Zr50Cu46Al4 metallic glass plates prepared by tilt-casting without using a silica nozzle. The amount of the ZrCu B2 phase precipitated in Zr50Cu46Al4 metallic glass ribbons prepared by using a silica nozzle decreases by Si diffused from the silica nozzle during the preparation. This work is discussed from the viewpoint of crystallization behavior and why larger Zr-based bulk metallic glasses can be formed by suction, tilt, and cap casting without using a silica nozzle.

In this paper, the influence of tarnishing film-induced stress and tarnishing film-induced brittle cracking on stress-corrosion cracking (SCC) of brass in Mattsson’s solution are investigated using hydrogen charging. Results showed that the SCC susceptibility of brass in Mattsson’s solution increased with the increase of tarnishing film-induced tensile stress. Also, the film-induced brittle cracking showed little effect on SCC susceptibility. From the results obtained, an improved SCC mechanism is proposed to explain the role of the tarnishing film-induced stress and the film-induced brittle cracking in SCC of brass in Mattsson’s solution. It seems that the film-induced brittle cracking is responsible for crack initiation of ductile brass. Also, the SCC susceptibility of brass in Mattsson’s solution was controlled by the growth rate of tarnishing film. Hydrogen enhanced the SCC susceptibility, which can be ascribed to the fact that hydrogen facilitates the tarnishing film growth.

In this paper, polycrystalline CuIn(SxSe1–x)2 thin films with tunable x and Eg (band gap) values were prepared by controlling the sulfurization temperature (T) of CuInSe2 thin films. X-ray diffraction indicated the CuIn(SxSe1–x)2 films exhibited a homogeneous chalcopyrite structure. When T increases from 150 to 500 °C, x increases from 0 to 1, and Eg increases from 0.96 to 1.43 eV. The relations between x and Eg and the sulfurization process of CuIn(SxSe1–x)2 thin films have been discussed. This work provides an easy and low-cost technique for preparing large area absorber layers of solar cell with tunable Eg.

The microstructure of Pt-modified γ′-Ni3Al + γ-Ni coating on CMSX-4 single-crystal superalloy has been investigated by transmission electron microscopy (TEM). Cross-sectional TEM analyses showed the presence of precipitates in the coating. This precipitate was identified as the hexagonal topologically close-packed (TCP) μ phase with lattice parameters a = 0.473 nm and c = 2.565 nm. The energy-dispersive x-ray (EDX) spectrum of the μ phase suggested a refractory element rich compound comprising the elements Re, W, and Co. Twin domains parallel to (001) were found in the μ phase. The mechanisms of the μ phase and twinning formation were discussed.

AlxIn1–xN films were grown on (0001) sapphire substrates by reactive radiofrequency (RF) magnetron sputtering in an ambient of Ar and N2. The XRD patterns are shown from AlxIn1–xN films grown on AlN/sapphire substrates using a wide range of magnetron power ratio settings. The wurtzite structure films have high crystal quality with full-width at half-maximum (FWHM) in the range of 0.22°–0.52°. The surface morphologies were observed by scanning electron microscopy (SEM). Raman spectra were measured on the AlxIn1–xN surfaces in a backscattering configuration at room temperature with 532 nm laser excitation and show A1(LO) bimodal behavior. Electrical resistivity and electron mobility were measured by the Hall effect method in the conventional Van der Pauw geometry at room temperature. The lowest electrical resistivity is 1 × 10−3 Ω·cm. This work suggests that reactive magnetron sputtering is a promising method for growing AlxIn1–xN films in over a large composition range.

Superhydrophobic membranes have the potential to protect devices from incidental exposure to water. This paper reports on the processing of Teflon AF fluoropolymers through electrospinning. Teflon AF is difficult to electrospin due to its low dielectric constant and the low dielectric constants of the liquids in which it is soluble. The two approaches that have been utilized to produce fibers are direct electrospinning in Novec engineering liquids and core-shell electrospinning. Both methods produced superhydrophobic membranes. Fibers with an average diameter of 290 nm and average water contact angle of 151° were obtained by core-shell electrospinning. One suggested application for electrospun superhydrophobic membranes is the lithium-air battery.

In this work, we propose a simple approach for designing plastic bulk metallic glasses (BMGs) by exploiting the ductility of intermetallic compounds involved in the BMG-forming system. Its validity was examined by investigating a series of quaternary Cu-Zr-Y-Al alloys along the composition tie-line between Cu42Zr44.4Y3.6Al10 (Y1) and the B2 CuZr phase, expressed as (Cu0.5Zr0.5)x(M)100-x (M = Zr0.15Y0.225Al0.625, 84≤x≤93). When tuning the composition towards the CuZr, the glass-forming ability of alloys is dramatically degraded, showing a reduction of critical diameter Dc for BMG formation from 16 mm at x = 84 (Y1) to 2 mm at x = 93. As the composition of BMGs shifts to the CuZr terminal, the shear modulus μ of the BMGs decreases, whereas the Poisson's ratio ν increases. With respect to the Y1 BMG, compressive plasticity and toughness of the Y2 BMG (x = 92, Dc = 4 mm) with a higher concentration of the CuZr are improved, which is consistent with its lower μ and higher ν values.

Aimed at designing an efficient visible light active photocatalyst and suppressing the self-corrosion tendency of CdS nanoparticles, a novel composite consisting of CdS nanoparticles and exfoliated two-dimensional (2D) TiO2 nanosheets was successfully fabricated using a simple self-assembly process. The prepared samples were characterized using various techniques including x-ray diffraction, ultraviolet–visible absorption spectroscopy, x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. It was found that the exfoliated 2D nanosheets played an important role as an ultrathin coating to suppress the photocorrosion of CdS nanoparticles, evidenced by inductively coupled plasma-atomic emission spectrometer analysis. The resultant CdS/TiO2 composites exhibited enhanced photocatalytic activity in the oxidation of Rhodamine B in water under visible light irradiation (λ > 420 nm).

Electromigration activation energy is measured by a built-in sensor that detects the real temperature during current stressing. Activation energy can be accurately determined by calibrating the temperature using the temperature coefficient of resistivity of an Al trace. The activation energies for eutectic SnAg and SnPb solder bumps are measured on Cu under-bump metallization (UBM) as 1.06 and 0.87 eV, respectively. The activation energy mainly depends on the formation of Cu–Sn intermetallic compounds. On the other hand, the activation energy for eutectic SnAg solder bumps with Cu–Ni UBM is measured as 0.84 eV, which is mainly related to void formation in the solder.

Metallic multilayers of Cu/Al/Ti composition were studied by transmission electron microscopy (TEM) and plasmon energy-loss mapping as prototypes of nanoscale reactive multilayer systems with exothermic alloy formation in oxygen-free conditions. The selection and arrangement of alloy phases by the system during ex situ and in situ heating experiments were found to depend not only on temperature but strongly on the initial volume ratios of metals, and to a lesser degree on the dimensionality of the reactive sample. Here, a two-dimensional sample was represented by ex situ heating of the full multilayer structure, a one-dimensional sample refers to in situ heating of thin cross-sectional TEM specimens, while a zero-dimensional sample (or metallic dot-array) was obtained after cutting thin pillars using focused ion beams. Lamellar self-organized alternation between Heusler phase and Cu9Al4 was found.

Cadmium sulfide (CdS) photocatalyst films were grown on glass by chemical bath deposition (pH 9.4, 70 °C) and then annealed in nitrogen from 423 K to 823 K in steps of 100 K. The XRD crystallite size increases in a sigmoidal manner from 60 nm to 100 nm while the optical band gap energy decreases from 2.42 eV to 2.28 eV. This trend is paralleled by the decreasing Urbach energy, but only up to 623 K, where it increases again. This is the temperature where the Cd effectively surpasses the phase transformation from cubic to hexagonal, and the activation energy for electronic transport drops by a factor of nearly two.

Interfacial reactions in Bi/Ni, Sn/Co, and Sn/Te systems that exhibit unique cruciform pattern formation are investigated. Different from the couples examined in the past, the solid substrates, Ni, Co, and Te, are placed outside the couples while constituents of low melting temperature, Bi and Sn, are placed in the center. With interfacial reactions proceeding in these couples, the reaction products grow inwardly at reentrant corners, and shrinking of the reaction layer at the corner is observed. As a result of the volumetric changes caused by interfacial reactions, stresses are built up in the couples, and stress-intensified locations are found at reentrant corners. The built-up stresses alter the diffusion rates and thus retard the reaction at the corners. Instead of forming cruciform patterns, the inner reactant is of flat shuriken shape after reactions.

The complexity of layered-spinel yLi2MnO3·(1 – y)Li1+xMn2–xO4 (Li:Mn = 1.2:1; 0 ≤ x ≤ 0.33; y ≥ 0.45) composites synthesized at different temperatures has been investigated by a combination of x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), and nuclear magnetic resonance (NMR). While the layered component does not change substantially between samples, an evolution of the spinel component from a high to a low lithium excess phase has been traced with temperature by comparing with data for pure Li1+xMn2–xO4. The changes that occur to the structure of the spinel component and to the average oxidation state of the manganese ions within the composite structure as lithium is electrochemically removed in a battery have been monitored using these techniques, in some cases in situ. Our 6Li NMR results constitute the first direct observation of lithium removal from Li2MnO3 and the formation of LiMnO2 upon lithium reinsertion.