Enthalpies of drop solution in molten 52 wt.% LiBO2-48 wt.% NaBO2 at 1078 K were measured for RE1.1Si1.7Al0.6O6-1.5xNx (x = 0, 0.2, 0.4, 0.6, 0.8) glasses for RE = Nd, Gd, Dy, Er, and Y. Linear relations between enthalpies of formation from elements and nitrogen content indicate that, within the experimental composition range, sites occupied by nitrogen ions are approximately equivalent in energy for a given substitutional series. The energetics of different rare-earth SiAlON glasses appears to be dominated by differences in the acid/base character of the cations. The onset glass-transition temperature increases linearly with increasing nitrogen content for the same rare earth and with decreasing rare-earth ionic radius for the same nitrogen content.

Using Ar-induced promotion of microcrystallization to the Si:H network, P-doped μc-Si:H films were prepared at a deposition rate of 50 Å/min. However, a large fraction of an amorphous component was identified, and a definite structural inhomogeneity was evident in the Si:H matrix. Efficient defect elimination, structural reorientation, and grain growth were performed, and an improved microcrystalline network with enhanced dopability was attained by introducing H2 to the Ar-assisted SiH4 plasma and by using their individual advantages to facilitate the microcrystallization process. A high conductivity of approximately 2 × 101 S cm−1 and a homogeneous distribution of micrograins of average diameter approximately 80 Å, contributing to a crystalline volume fraction of 67% in the matrix, were obtained. A significant achievement was to maintain microcrystallinity at a very low thickness of the bulk layer. The n-type μc-Si:H film of dark conductivity approximately 100 S cm−1 was realized at a thickness of approximately 350 Å with a deposition rate of 24 Å/min. Using this material at the tunnel junction as well as at the bottom layer of a double-junction a-Si solar cell, a conversion efficiency of 11.7% was attained without compromising the other parameters.

Epitaxial thin films of PbZr0.52Ti0.48O3 (PZT) were synthesized successfully on SrRuO3/SrTiO3/MgO/TiN/Si heterostructures by pulsed laser deposition. The films were single phase and had (001) orientation. The deposition parameters were varied to obtain the best epitaxial layer for each of the compounds. Transmission electron microscopy indicated good epitaxy for the entire heterostructure and sharp interfaces between the epilayers. Dielectric and P–E hysteresis loop measurements were carried out with evaporated Ag electrodes. The dielectric constant for the films was found to be between 400–450. The value of saturation polarization Ps was between 55–60 μC/cm2, and the coercive field Ec varied from 60–70 kV/cm. Integration of PZT films with silicon will be useful for future memory and micromechanical devices.

The effect of furfuryl alcohol addition to ordinary cement on its properties, such as heat of hydration, setting time, compressive strength, and tensile strength was studied by adding 0.5–3.0% by weight of cement. Hardness was tested using the Vickers indentation method. Fracture toughness of cementitious bond and bending strength were determined using the three-point bending system. Corrosion resistance of resulting products was tested against 0.1 and 1.0 N HCI and H2SO4 and seawater, respectively. Water absorption/open porosity and microstructure were also determined. It was observed that strength, hardness, toughness, and corrosion resistance increase up to 3.0% addition of furfuryl alcohol in ordinary Portland cement. Polymeric phase was interspersed in cement, causing a decrease in water absorption/open porosity, and its interaction with hydrating cement caused additional bond formation, leading to the increase in strength.

Uniform hexagonal prismatic zinc oxide rods were grown over the entire alumina substrate at 550°C using a two-step oxygen injection process, whether the substrates were coated with a catalyst or not. X-ray diffraction showed that all of the depositions exhibited a preferred orientation in the (002) plane. The influence of oxygen concentration was investigated by changing the oxygen flow rate. Oxygen concentration affected the size of ZnO nanorods, especially the diameter. The ZnO nanorods were further checked using high-resolution transmission electron microscopy, photoluminescence, Raman spectroscopy, and room-temperature ultraviolet lasing. The results showed that the rods were single crystals and had excellent optical properties. By observing the growth process, we found that the diameter increased slowly, but the longitudinal growth rate was very high. The growth of ZnO nanorods revealed that the uniform hexagonal prismatic ZnO nanorods were synthesized through vapor deposition growth and a self-catalyzed vapor–liquid–solid (VLS) process.

To prevent catastrophic failure by propagating highly localized shear bands and to overcome the limited dimension of metallic glass, centimeter-scale Ni59Zr20Ti16Si2Sn3 bulk metallic glass matrix composites were fabricated by warm extrusion of a mixture of gas-atomized fully amorphous powders and ductile brass powders. After consolidation, the composite retained the fully amorphous matrix found in the gas-atomized powder combined with the brass second phase. The glass-transition and crystallization temperatures of the extruded material were the same as those of the starting powders. The confined ductile brass phase enabled the bulk metallic glass matrix composites to deform plastically under uniaxial compression at room temperature. The combination of strength and ductility in the inherently brittle Ni-based monolithic materials could be obtained by introducing a ductile phase in the bulk metallic glass matrix. However, control of the volume fraction and distribution of the ductile brass phase was important for the proper combination of the strength and plasticity.

The synthesis of Au and Ag metal nanoparticles stabilized by G4, G5, and G6 hyperbranched poly(amine–ester) (HPAE) is reported. The reduction of hydrogen tetrachloroaurate and silver nitrate in the presence of HPAE resulted in the formation of stable, uniform, water-soluble nanoparticles. The average particle sizes are (2.4 ±0.5)–(4.1 ±0.4) nm for Au and (2.5 ±4.9)–(10.3 ±1.7) nm for Ag, depending on the generation of HPAE and metal ion-to-end tertiary amine of HPAE (M:N) used. All of the obtained colloidal solutions are stable for a long period of time. The results from ultraviolet–visible absorption spectra and Fourier transform infrared absorption spectroscopic investigations confirm the interactions between metal and HPAE.

This paper aims at establishing a number of electrons/atom (e/a)-based criterion for searching bulk metallic glasses (BMGs) and quasicrystals with large forming abilities in the Zr-based multicomponent alloy systems. After discussions on the diffraction characteristics corresponding to the Fermi surfaces-Brillouin zone interaction in the Zr-based Hume-Rothery phases, the Hume-Rothery matching rule is well explained when the effective e/a value of the matrix element Zr is taken as 1.5. The BMG- and quasicrystal-related phases are pointed out to be a family of nearly e/a-constant phases in a given alloy system. An e/a-constant criterion is then used to predict the ideal composition of the quasicrystals and BMGs in the Zr-Ti-Ni, Zr-Al-Ni, and Zr-Al-Ni-Cu systems, respectively. Nearly pure bulk Zr-Ti-Ni quasicrystals and a series of BMGs with glass-forming abilities greater than that of the known Zr65Al7.5Ni10Cu17.5 alloy are found.

Highly conductive cubic (Y0.25Bi0.75)2O3 tends to transform to rhombohedral (Y0.25Bi0.75)2O3 when annealed at 600°C for more than 200 h. Although the rhombohedral phase of (Y0.25Bi0.75)2O3 was known to be the stable phase at temperatures ≤600°C, it was found that the annealed (Y0.25Bi0.75)2O3 was not thermodynamically stable in the water-containing environment. From x-ray diffraction and transmission electron microscopy analysis, it was observed that the annealed (Y0.25Bi0.75)2O3 easily decomposed into monoclinic α-Bi2O3 and yttrium hydroxide at a temperature as low as 50°C. The monoclinic α-Bi2O3 further reacted with CO2 and formed Bi2O2CO3. Consequently, the annealed (Y0.25Bi0.75)2O3 degraded and became flaky powder. Scanning electron microscopy micrographs of water-reacted (Y0.25Bi0.75)2O3 also showed surface swelling and peeling. Such surface deterioration was caused by a large volume increase during the water reaction. Similar reaction was also observed when the annealed (Y0.25Bi0.75)2O3 was exposed in the humidified air at 300°C. As the temperature was raised to 500°C, little reaction was observed between water vapor and (Y0.25Bi0.75)2O3. The better stability of (Y0.25Bi0.75)2O3 at elevated temperature was observed.

Room-temperature indentation experiments carried out on nanocrystalline Ni75at.%Al25at.% alloy films with a range of grain sizes revealed that the strain-rate sensitivity of hardness is nearly zero and that the hardness increases as grain size decreases. The strain-rate insensitivity of hardness indicates that the room-temperature strength of these alloy films is dominated by an athermal, strain-rate-insensitive component. The hardness of the films was found to be in the range of 2.4 to 3.3 GPa, depending on grain size.

Thermal stress characteristics of single-level and two-level Al(Cu) interconnects passivated with tetraethyl orthosilicate oxide were measured using x-ray diffraction. Thermal stresses of the second-level metal lines were deduced from the experimental data based on an analysis of the x-ray absorption in a two-level interconnect structure. The confinement effect from the substrate on the stress characteristics of metal lines at different interconnect levels was investigated. Thermal stress behavior of the second-level lines indicated that the confinement effect from the Si substrate is reduced compared to the single-level lines, resulting in reduced levels of hydrostatic and shear stresses.

Mechanically alloys in the Al–Mg binary system in the range of 5–50 at.% Mg were produced for prospective use as metallic additives for propellants and explosives. Structure and composition of the alloys were characterized by x-ray diffraction microscopy (XRD) and scanning electron microscopy. The mechanical alloys consisted of a supersaturated solid solution of Mg in the α aluminum phase, γ phase (Al12Mg17), and additional amorphous material. The strongest supersaturation of Mg in the α phase (20.8%) was observed for bulk Mg concentrations up to 40%. At 30% Mg, the γ phase formed in quantities detectable by XRD; it became the dominating phase for higher Mg concentrations. No β phase (Al3Mg2) was detected in the mechanical alloys. The observed Al solid solution generally had a lower Mg concentration than the bulk composition. Thermal stability and structural transitions were investigated by differential scanning calorimetry. Several exothermic transitions, attributed to the crystallization of β and γ phases were observed. The present work provides the experimental basis for the development of detailed combustion and ignition models for these novel energetic materials.

A simple pulse sonoelectrochemical technique was used to synthesize highly dispersed spherical palladium particles and a dendritic Pd superstructure in the presence of cethyltrimethylammonium bromide (CTAB) at room temperature. The shape and size of spherical nanocrystalline Pd can be controlled by varying current density, the interval between two continuous ultrasonic pulses, ultrasonic intensity, and the concentration of CTAB. The possible growth mechanism of dendritic-structured Pd is discussed.

A cosolvent-assisted spray pyrolysis process was developed for the formation of phase-pure metal particles from metal salt precursors without the direct addition of hydrogen or other reducing gas. Generation of phase-pure copper and nickel particles from aqueous solutions of copper acetate, copper nitrate, and nickel nitrate over the temperature range of 450 to 1000 °C was demonstrated. Addition of ethanol as a cosolvent plays a crucial role in producing phase-pure metal powders. Results of a modeling study of ethanol decomposition kinetics suggest that cosolvent decomposition creates a strong reducing atmosphere during spray pyrolysis via in situ production of hydrogen and carbon monoxide.

Polypropylene (PP) and amorphous selenium (a-Se) were used as prototype materials at room temperature to explore the problems that may exist in the accurate measurement of the reduced modulus of viscoelastic materials using depth-sensing nanoindentation. As has been reported previously by others, we observed that a “nose” in the load-displacement curve may occur during unloading, indicating significant creep effects at the onset of unloading. To accurately measure the elastic modulus in viscoelastic materials like PP or a-Se, both the contact stiffness and the contact area at the onset of unloading must be determined accurately. The issue of removing the influence of creep on the measurement of the contact stiffness using the Oliver-Pharr method has been addressed in a previous paper by Feng and Ngan. In this work, the effect of creep on contact-depth measurement is considered. Removal of creep effects in both contact stiffness and contact-area measurement leads to satisfactory prediction of the reduced moduli in PP and a-Se.

Sr0.7Bi2.4Ta2O9 (SBT) thin films were deposited on unseeded and SBT nanoparticle (approximately 60–80 nm) seeded Pt/Ti/SiO2Si substrates via sol-gel and spin-coating techniques. The SBT thin films were heated at 600 °C for 1 h to form the fluorite phase, and these fluorite films were further heated at 730–760 °C for fluorite-to-Aurivillius phase transformation. The volume fractions of Aurivillius phase formation obtained through quantitative x-ray diffraction analyses showed highly enhanced kinetics in seeded SBT thin films. Johnson–Mehl–Avrami isothermal kinetic analyses were performed for the characterization of Aurivillius phase formation in unseeded and seeded SBT thin films using the volume fraction values. The Avrami exponents were determined as approximately 1.4 and approximately 0.9 for unseeded and seeded SBT films, respectively, which reveals different nucleation modes. By using Arrhenius-type plots, the activation energy values for the phase transformation of unseeded and seeded SBT thin films were determined to be approximately 264 and approximately 168 kJ/mol, respectively. This gives a key reason for the enhanced kinetics in seeded films. Microstructural analyses on unseeded SBT thin films showed formation of randomly oriented needlelike crystals, while those on seeded ones showed formation of domains comprising directionally grown wormlike crystals. On the basis of the phase formation kinetics and microstructural development, a model representing different nucleation and crystal growth mechanisms for the unseeded and seeded SBT thin films was proposed.

In this paper, we report on the synthesis and structure of hierarchical zinc oxide nanotubes. Hierarchical nanotubes grown by physical vaporization of zinc in the presence of a catalyst were decorated with many secondary zinc oxide nanorods on the outer surface. The axis of these nanotubes with an average diameter of 65 nm was aligned along the c axis of wurtzite zinc oxide. The hierarchical zinc oxide nanotubes, many of which were single crystals, were transparent or opaque, depending on whether they had a zinc layer inside. The opaque nanotubes showed an abrupt change in electronic transmittance during investigation with transmission electron microscopy. The unique structure of the hierarchical ZnO nanotubes and the quantum effect resulting from the reduced dimension will modify the original properties of ZnO, leading to novel applications.

Kinetic spray deposition provides a new means for producing composite materials with tailored physical properties. We report on measurements of the thermal conductivity and thermal-expansion coefficient for several compositional variations of kinetically sprayed Al–SiC metal-matrix composites. As a result of the deposition process, inclusion of SiC particles saturates in the 30–40% volume fraction range.

The effects of dilution of tetraethyl orthosilicate (TEOS) with ethanol on the shape and monodispersity of silica particles were investigated. The results indicated that the dilution of TEOS with ethanol can depress the formation of new nuclei and the aggregation or adhesion of particles and make the distillation of TEOS unnecessary to achieve monodispersed silica spheres. A seeded growth technique using continuous drop addition of TEOS diluted with 4× volume of ethanol was developed to improve monodispersity and spheric shape and increase the size of silica particles. The monodisperse silica particles (150 nm ± 5%−1.2 μm ± 1%) with fine spheric shape were successfully synthesized by the seeded growth technique. Using the homemade 280 nm ± 2.8% silica spheres, we prepared opals of high quality which showed periodically ordered packing and a photonic band-gap effect.

The oxidation behavior in air of gas atomized Al–Cu–Fe–Be powders was investigated during isothermal exposures at 750, 800, and 830 °C. Oxidation data obtained at 750 °C for Al–Cu–Fe and Al–Cu–Fe–Cr powders are also presented and used as references. Thermogravimetric analyses showed that Be significantly improved the oxidation resistance of the icosahedral phase at 750 °C. At this temperature the i-phase in Al–Cu–Fe–Be powders was found to be stable even after oxidation for 300 h, while oxidation at and beyond 800 °C led to the formation of a cubic β′-phase. Auger analyses suggested that, in addition to its role on the stability of the icosahedral phase, the presence of Be in the oxide layer provided efficient protection against air oxidation at high temperature.