Near-ternary eutectic Sn–Ag–Cu alloys are leading candidates for Pb-free solders. These alloys have three solid phases: β–Sn, Ag3Sn, and Cu6Sn5. Starting from the fully liquid state in solidifying near-eutectic Sn–Ag–Cu alloys, the equilibrium eutectic transformation is kinetically inhibited. The Ag3Sn phase nucleates with minimal undercooling, but the β–Sn phase requires a typical undercooling of 15 to 30 °C for nucleation. Because of this disparity in the required undercooling for nucleation, large, platelike Ag3Sn structures can grow rapidly within the liquid phase, before the final solidification of the solder joints. At lower cooling rates, the large Ag3Sn plates can subtend the entire cross section of solder joints and can significantly influence the mechanical deformation behavior of the solder joints under thermomechanical fatigue conditions. In this paper, it is demonstrated that the Ag3Sn plate formation can be inhibited, an important factor in assuring the reliability of solder joints composed of these alloys.

Barium indium oxides (BaIn2O4, Ba4In6O13, Ba2In2O5, Ba3In2O6, and Ba5In2O8) were synthesized by the citric process and characterized by powder x-ray diffraction. The optical absorption properties of these compounds were investigated by UV–visible diffuse reflectance spectroscopy. It was found that with the increase of the mole ratio of In2O3 in the formula the optical absorption edges of these oxides shift to the longer wavelength side monotonically. The photocatalytic H2 and O2 evolutions under visible light irradiation (λ > 420 nm) from aqueous CH3OH/H2O and AgNO3/H2O solutions were performed. Among these oxides, BaIn2O4 was the most stable compound, and other compounds were not stable chemically in the case of water and visible light irradiation.

We demonstrate in this paper that common crystalline phases can be made noncrystalline and hard magnets can be converted to soft magnets in the solid state in several seconds at temperatures far below the melting points. New crystal structures and magnetic structures of ferromagnetic oxides (ferrites such as BaFe12O19, CoFe2O4, Fe3O4, and ZnFe2O4, etc.) are formed by reacting either the stoichiometric mixture of oxides or the preformed phase-pure crystalline material in a pure H field (or E field) at microwave (2.45 GHz) frequencies. These major changes in the magnetic properties as well as major structural phase changes are caused by the magnetic field.

The single crystals of a binary organic 1:1 molecular complex were grown from different solvents. The single crystal x-ray diffraction study revealed that the binary material has crystallized with a noncentrosymmetric space group (P21) entirely different from that of the parent components. Second harmonic generation measurement on polycrystalline material shows green light emission with the molecular complex. The differential scanning calorimeter and the thermogravimetric analysis show eminent higher melting point and decomposition temperature, respectively for the binary molecular complex compared to that of urea and m-nitrobenzoic acid. The optical spectrum of newly grown crystal shows the cutoff wavelength (398 nm) near the UV region, and the micro hardness measurement confirmed the greater hardness of the binary crystal.

A new process combining electric field activation and the imposition of pressure from mechanically activated powder mixtures is demonstrated as a means to simultaneously synthesize and densify nano-MoSi2 in one step. Nanophase reactants (Mo + 2Si) produced by mechanical activation are reacted by field activation with the simultaneous application of a uniaxial pressure. Mo + 2Si powders were comilled in a specially designed planetary mill to obtain nanometric reactants but to avoid formation of any product phases. These were then subjected to high alternating currents (1600 A) and pressures of 106 MPa. Under these conditions, a reaction is initiated and completed within a short period of time (3–6 min). The relative density of the product ranged from 82 to 93%. The crystallite size of the MoSi2 compound was determined by x-ray diffraction line-broadening analysis using the Langford method. The size ranged from 58 to 75 nm.

Thin films of TiNi shape memory alloy have been prepared by pulsed-laser deposition at different substrate temperatures. The stoichiometry and crystallinity of the deposited films as functions of the substrate temperature were investigated. The deposition rate, surface morphology, crystallization temperature, and phase transformation behavior of the films were studied. It was found that both the substrate temperature and the laser fluence play important roles in the composition control and crystallization of the films. The deposition rate is of the order of 10−2 nm/pulse. The Ni content ranges from 46.7 to 52.0 at.%. The crystallization temperature of the amorphous Ti–51.5 at.% Ni films is around 460 °C. The activation energy of the crystallization process was determined by Kissinger's method to be 301 kJ/mol. The martensitic transformation temperature of the annealed Ti–51.5 at.% Ni film was determined to be −20.8 °C.

Atomic force microscopy (AFM) nanoindentation experiments were performed on a Co(10.1) monocrystal. Using AFM line scans, we deduced the elastic recovery, which is an intrinsic parameter of the studied material. The comparison of these elastic recovery values with those calculated by standard nanoindentation shows a fair agreement for forces higher than 400 μN with an important discrepancy for lower forces. This difference is attributed to tip shape effects and to the AFM cantilever elastic deformation. Furthermore, the material hardness was measured from AFM images of the imprint by considering the lateral dimension L. In this case, the obtained values are practically independent from the applied load. Moreover, a simple model based on geometrical considerations is proposed to correct hardness values calculated from the residual depth.

A high quantity and yield (up to 85%) of boron nitride (BN) nanotubes have been produced using a mechanothermal method. Elemental boron powders were first mechanically milled at room temperature in NH3 atmosphere and subsequently heated in N2 gas at 1200 °C for up to 16 h. The BN nanotubes obtained have either multiwalled cylindrical or bamboolike structures, suggesting different growth processes. The high formation yield of BN nanotubes is due to a high density of nanostructured nuclei created by an extensive milling treatment.

Single-wall carbon nanotube (SWNT)/poly(methyl methacrylate) (PMMA) composites were fabricated and exposed to ionizing radiation for a total dose of 5.9 Mrads. Neat nanotube paper and pure PMMA were also exposed for comparison, and nonirradiated samples served as controls. A concentration of 0.26 wt% SWNT increased the glass transition temperature (Tg), the Vickers hardness number, and modulus of the matrix. Irradiation of the composite did not significantly change the Tg, the Vickers hardness number, or the modulus; however, the real and imaginary parts of the complex permittivity increased after irradiation. The dielectric properties were found to be more labile to radiation effects than mechanical properties.

Ferroelectric SrBi2Ta2O9 (SBT) thin films and Bi2O3 interfacial layers were depositedonto the Pt/Ti/SiO2/Si substrates via liquid-delivery metalorganic chemical vapordeposition. The SBT films with a 5-nm-thick Bi2O3 interfacial layer were well crystallized without c-axis orientation, even at deposition temperature of 540 °C and showed a stronger (115) orientation than those without a Bi2O3 layer with increasing annealing temperature. The remanent polarizations of SBT films with Bi2O3 interfacial layer were significantly improved in comparison with those without Bi2O3 layer. The remanent polarization (2Pr) and coercive field (Ec) of SBT films without and with aBi2O3 interfacial layer annealed at 750 °C were 12 and 21 μC/cm2 and 60 and38 kV/cm, respectively, at an applied voltage of 5 V.

The microstructure and adhesion strength of the Sn–0.7Cu/Cu solder joints were examined. The acicular η(Cu6Sn5)-phase was formed inside the solder and at the solder/Cu interface, mostly in the direction normal to the interface. Compared to the Sn–3.5Ag alloy, the Sn–0.7Cu solder showed comparable wettability, but lower microhardness and joint strength. After aging, the acicular η-phase grew into a round and scallop-shaped morphology, thin є(Cu3Sn)-phase evolved just above the Cu substrate, and the joint strength decreased linearly with aging time.

ZnO nanoparticles were mixed with branched low-density polyethylene and were found to increase the resistance of the polymer to thermal degradation without changing other thermal properties. Submicron-size ZnO particles were mixed with low-density polyethylene for comparison, and it was found that the increased thermal stability of the nanocomposite was due to the surface properties of nanoparticles smaller than approximately 100 nm in diameter.

We have analyzed Tb L3-edge x-ray absorption near-edge structure spectra of Tb-doped phosphor compounds for plasma display panel applications. Intensity and lifetime of the green emission from the Tb3+:5D4→7F5 transition were measured with respect to nominal terbium concentration in the host compounds, i.e., YBO3, YPO4,and Y4Al2O9, all of which were made through the solid-state reaction. Typical concentration quenching was evident on the fluorescence intensity and the fluorescing level lifetime in our samples. From the analyses of white line absorption peaks at TbL3-edge, it was verified that terbium is essentially trivalent in all the samples, even invery highly concentrated ones. Thus, this implies that the concentration quenching was not caused by presence of mixed-valent states of terbium. Instead, it is believed that anonradiative energy transfer route among Tb3+ ions might be responsible for thebehavior.

Iodine-doped whiskers of C60 (I–C60 whiskers) with diameters ranging from submicrometers to micrometers and lengths longer than 100 μm were successfully obtained by the use of the liquid–liquid interfacial precipitation method. Transmission electron microscopy observations showed that the I–C60 whiskers were single crystalline and had a growth axis parallel to the close-packed direction of C60 molecules and expanded (002) lattice planes indicative of the intercalation of iodine and oxygen atoms between the (002) planes of a body-centered-tetragonal crystal system. The I–C60 whiskers showed nonlinear I-V curves. The electrical resistivity of the I–C60 whiskers was more than three orders of magnitude lower than that of pristine face-centered-cubic C60 crystals.

Phase transformation about precipitation in a Cu–Zn alloy was studied. It was found that with an electropulsing treatment the number of nuclei during phase transformation could be dramatically enhanced and nucleation of precipitates was more homogeneous. The phenomena did not result from the effect of rapid heating or rapid cooling during electropulsing but resulted from the electric current itself. The results were in good agreement with the theoretical model that electric current can increase nucleation by decreasing the thermodynamic barrier during phase transformation.

The effect of high-boiling-point solvent addition on the morphology of low-p(O2) processed, sol-gel YBa2Cu3O7−δ (YBCO) films is discussed. Proper selection and addition of a high-boiling-point solvent prevents film roughening during precursor pyrolysis, while permitting at least a tenfold reduction in pyrolysis time compared to standard film processing in air or O2. Use of such solvents appears to increase film plasticity, avoiding elastic compressive stress related buckling. High-quality YBCO films on 〈100〉 LaAlO3 with a critical current density (Jc) ∼ 3–4 MA/cm2 at 77 K, are routinely crystallized with this new sol-gel process. Diethanolamine-based, sol-gel YBCO films deposited on sol-gel SrTiO3-buffered 〈100〉 Ni have Jc(77 K) > 1 MA/cm2, demonstrating a route toward all-sol-gel superconducting wires.

TiC nanoparticles (average diameter 10–150 nm) were prepared by reacting bulk Ti powders (average diameter 20 μm) with gaseous 1-chlorobutane at a relatively low temperature (1073–1273 K). 1-Chlorobutane provided the carbon atom in the TiC and the chlorine atom that assisted the shrinking of the size of the original Ti powders. The apparently simple procedure is a complex heterogeneous process combining etching, deposition, and carburization reactions.

The main objective of this work is to examine the feasibility of depositing aluminum nitride (AlN) powders, synthesized using self-propagating high-temperature synthesis, on a mild steel substrate using the detonation spray coating technique. Thick coatings produced by utilizing the AlN powder were obtained at four different oxygen–acetylene ratios and analyzed for microstructure, microhardness, porosity, indentation fracture toughness, and phase distribution. The AlN powder particles were found to be undergoing oxidation during the deposition process. The interrelationship between the spray parameters and the extent of oxidation of AlN during the coating process was investigated. Tribological performance of the coatings was evaluated using a dry sand abrasion test and a pin-on-disc sliding wear test. The mechanical and tribological properties of the above four coatings were compared with pure alumina (Al2O3) coatings. The correlation between the structure of the coatings and their tribological performance was also established.

YBa2Cu3O7−y(Y123) and Nd1+xBa2−xCu3O7−y (Nd123) films were deposited by the metalorganic deposition method, and the growth mechanism of these films was investigated by high-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy. The Y123 and Nd123 films were prepared by spin-coating LaAlO3 (001) and SrTiO3 (STO) (001) substrates, respectively, with solutions including trifluoroacetates. Then, the samples were heat treated at 673 K in a humid O2 gas flow to form amorphous precursor films. Finally, the precursor films were heated at higher temperatures for 0–30 min in a humid Ar/O2 gas flow and cooled rapidly from those annealing temperatures. It was found that CuO crystals with a size of 10–20 nm are segregated in the Y123 and Nd123 amorphous precursor films. In the Y123 quenched film prepared by cooling the precursor film rapidly after the heat-treatment at 1048 K for 30 min, a polycrystalline film including Y2Cu2O5, BaF2, and CuO crystals was found to be generated on the c-axis-oriented Y123 film. In contrast, in the Nd123 quenched films, (NdBa)2CuO4(Nd201) phase was found to be formed first on the surface of the STO substrate. In conclusion, the c-axis-oriented Y123 film is formed by diffusion and reaction of Y2Cu2O5, BaF2, and CuO crystals, and the Nd201 phase reacts with BaF2 and CuO crystals in a humid atmosphere to form a c-axis-oriented Nd123 film.

The crystallization behavior of amorphous TiOxNy (x ≫ y) thin films was investigated by in situ transmission electron microscopy. The Johnson–Mehl–Avrami–Kozolog (JMAK) theory was used to determine the Avrami exponent, activation energy, and the phase velocity pre-exponent. Addition of nitrogen inhibited diffusion, increasing the nucleation temperature, while decreasing the growth activation energy. Kinetic variables extracted from individual crystallites were compared to JMAK analysis of the fraction transformed, and a change of 6% in the activation energy led to agreement between the methods. From diffraction patterns and index of refraction the crystallized phase was found to be predominantly anatase.