Measurements of single asperity wear on oxidized silicon surface in aqueous potassium hydroxide (KOH) using atomic force microscopy (AFM), where the single crystal silicon tip was used both to tribologically load and image the surface, is presented. AFM was also operating in the lateral (frictional) force mode to investigate the pH dependence of kinetic friction between the tip and the SiO2 surface. It was shown that the Si tip wear amount strongly depended on the solution pH value and was at a maximum at around pH 10. It was also found that the Si removal volume in mol was approximately equal to that of SiO2 irrespective of the solution pH value. This equality implies that the formation of the Si–O–Si bridge between one Si atom of the tip and one SiO2 molecule of the specimen at the wear interface. The surface of the Si tip is then oxidized. Finally, the bond rupture by the tip movement will occur, the dimeric silica (OH)3Si–O–Si(OH)3, including the Si–O–Si bridge, is dissolved in the KOH solution. The frictional signal is also sensitive to the pH values of the solution and peaked at around pH 10. These results indicate that the removal behavior of the Si tip and SiO2 surface would be affected by the frictional force between the Si and the SiO2, because of an increased liquid temperature and a compressive stress in Si and SiO2 networks. Strong influence is observed by the pH of the ambient solution confirming the important role of the OH− in the wear mechanism. Pressure dependence of the microwear behavior under aqueous electrolyte solutions has also been investigated. A microscopic removal mechanism, which is determined by interplay of the diffusion of water in Si and SiO2, is presented.

Spark plasma sintering (SPS) of a codoped α-alumina powder has been investigated at temperatures between 850 and 1200 °C. The “grain size versus relative density” trajectory showed a significant grain growth as soon as the residual porosity closed. The densification mechanism was determined by anisothermal (investigation of the heating part of a SPS run) and isothermal methods. It was proposed that grain-boundary sliding, accommodated by oxygen grain-boundary diffusion, governed densification.

A high quantity of tungsten oxide nanosheets were synthesized by oxidizing tungsten plates with potassium hydrate as the catalyst and tungsten plate as the substrate. The structural and geometrical properties were characterized by various techniques. It was found that the crystalline nanosheets have a WO3 structure with thicknesses of 30–50 nm and widths up to tens of micrometers. There exist two characteristic acute angles of about 37° or 51° on the nanosheet plane. The formation of these angles and the growth mechanism were discussed.

The orientation relationship (OR) and the interfacial structure between Nb solid solution (Nbss) precipitates and α-Nb5Si3 intermetallics have been investigated by transmission electron microscopy (TEM). The OR between Nbss and α-Nb5Si3 was determined by selected-area electron diffraction analyses as (222)Nb//(002)α and . High-resolution TEM images of the Nbss/α-Nb5Si3 interface were presented. Steps existed at the interface that acted as centers of stress concentration and released the distortion of lattices to decrease the interfacial energy. In addition, the interfacial models were proposed based on the observed OR to describe the atomic matching of the interface. The distribution of alloying elements at the Nbss/α-Nb5Si3 interface has also been investigated, and Hf was enriched at the interface to strengthen the grain boundary.

The dynamic mechanical behavior, fracture characteristics, and microstructural evolution of high-strength weldable aluminum-scandium (Al–Sc) alloy were investigated using a compressive split Hopkinson pressure bar at strain rates of 1.3 × 103, 3.6 × 103, and 5.9 × 103 s−1, respectively, and temperatures of −100, 25, and 300 °C. The results showed that the flow stress, work hardening rate, and strain rate sensitivity increase with increasing strain rate but decrease with increasing temperature. Conversely, the activation volume and activation energy increase as the temperature increases or the strain rate decreases. Moreover, the fracture strain decreases with increasing strain rate and decreasing temperature. It was shown that the Zerilli–Armstrong face-centered-cubic (fcc) constitutive equation provides accurate predictions of the mechanical response of the Al–Sc alloy under the considered strain rate and temperature conditions. Scanning electron microscopy observations revealed that the fracture surfaces of the impacted specimens are characterized by transgranular dimpled features, which are indicative of a ductile failure mode. Moreover, transmission electron microscopy observations indicated the presence of both fine and coarse randomly dispersed precipitates within the matrix and at the grain boundaries. It was found that an increasing strain rate reduces the size of the dislocation cells within the impacted Al–Sc microstructure and therefore increases the dislocation density. However, at higher temperatures, the dislocations are annihilated, leading to a reduction in the dislocation density and a corresponding increase in the dislocation cell size. The variations observed in the size and density of the dislocation cells were found to be consistent with the dynamic tendencies noted in the stress–strain response of the Al–Sc alloy.

We report the systematic substitution of Nb at the Cu1 site of YBa2Cu3Oy in thin films to form a new phase of YBa2Cu2NbO8. These films were deposited on SrTiO3(100) crystals using pulsed laser deposition and deposited at an optimal temperature of 850 °C. Films were characterized using x-ray diffraction (XRD), atomic force microscopy, x-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, and transmission electron microscopy. XRD of these films indicate c-axis oriented YBa2Cu2NbOy formation. XPS and micro-Raman spectroscopy analysis suggests Cu exists in the +2 state.

Ultrafine-grained samples were produced from a Ni nanopowder by hot isostatic pressing (HIP) and spark plasma sintering (SPS). The microstructure and mechanical behavior of the two specimens were compared. The grain coarsening observed during the SPS procedure was moderated due to a reduced temperature and time of consolidation compared with HIP processing. The smaller grain-size and higher nickel-oxide content in the SPS-processed sample resulted in a higher yield strength. Compression experiments showed that the specimen produced by SPS reached a maximal flow stress at a small strain, which was followed by a long steady-state softening while the HIP-processed sample hardened until failure. It was revealed that the softening of the SPS-processed sample resulted from microcracking along the grain boundaries.

Under γ-irradiation, thiacetamide (TAA) releases S2− in acidic solutions (e.g., pH = 3), and the S2− can react with available Cd2+ in soft templates to form CdS nanorods. Single-crystalline CdS nanorods were prepared in this study. The effects of various synthesis parameters on the crystalline type, morphology, average particle size, and photoelectric properties were thoroughly investigated, including the concentrations of reactants, dose of irradiation, and the type and dosage of templates. The structure and selected physical and chemical properties of products were characterized by x-ray diffraction (XRD), Fourier transform infrared (FTIR), ultraviolet-visible (UV-vis), selected area electron diffraction (SAED), transmission electron microscopy (TEM), and photoluminescence (PL) spectrophotometer techniques. Results indicated that the ratio of reactants to templates greatly affected the morphology of CdS nanorods; the types of soft templates also had significant effects on the morphology and crystalline type of the nanorod products.

Highly sinterable La10Si6O27 and La10Si5.5M0.5O27 (M = Mg, and Al) nanopowders with apatite-type structure have been synthesized via a homogeneous precipitation method using diethylamine (DEA) as a precipitant. The synthetic approach using an organic precipitant with dispersant characteristics is advantageous in configuring weakly agglomerated nanopowders, leading to desirable sintering activity. X-ray diffraction powder patterns confirmed the single-phase crystalline lanthanum silicate of hexagonal apatite structure at 800 °C, which is a relatively lower calcination temperature compared to conventionally prepared samples. Transmission electron microscopy images revealed particles ∼30 nm in size with a high degree of crystallinity. A dense grain morphology was recognized from the scanning electron microscopy images of the polished surface of the pellets that were sintered at 1400 and 1500 °C for 10 h. This low-temperature sintering is significant because conventional powder processing requires a temperature above 1700 °C to obtain the same dense electrolyte. The doped-lanthanum silicate electrolyte prepared by the DEA process and sintered at 1500 °C for 10 h exhibited electrical conductivity comparable with samples prepared at much higher sintering temperature (>1700 °C).

Single-phase nanocrystalline 4CaO·Al2O3·Fe2O3 powders were prepared directly from the combustion reaction using a new cost-effective, time-saving, and environmentally friendly version of solution combustion synthesis. Instead of a single fuel, a fuel mixture of urea and β-alanine was used. It was shown by x-ray diffraction, energy-dispersive x-ray analysis, thermogravimetric analysis, and optical microscopy that this new version of the solution combustion synthesis allows the maximization of the exothermic effect associated with the combustion reaction. On the other hand, it was shown that the traditional version of combustion synthesis involving the use of a single fuel, such as urea or β-alanine, does not ensure the formation of Ca4Al2Fe2O10 unless subsequent thermal treatments are applied. It was suggested that the occurrence of combustion reactions cannot be regarded only in terms of adiabatic temperature, as the kinetic aspects overrule the thermodynamic ones.

Gold-coated polystyrene (PS) beads were fabricated by an in situ metallization route involving a cationic-gold complex with a controlled amount of sulfonic acid groups formed on the PS bead surface. The interaction ratio of SO3− to [Au(phen)Cl2]+ may be estimated to be 2.4, which means that 2.4 sulfonated groups will interact with one gold cationic ligand based on geometric considerations. A modeling methodology was developed to predict the mechanical deformation, conductivity, and contact surface area of a spherical bead under compression.

A modified heat treatment process designated quenching–partitioning–tempering (Q–P–T) process is developed based on the quenching and partitioning process proposed by J.G. Speer et al. [Acta Mater.51, 2611 (2003)] and D.K. Matlock et al. [Mater. Sci. Forum426–432, 1089 (2003)]. A Fe–0.485C–1.195Mn–1.185Si–0.98Ni–0.21Nb steel after Q–P–T process satisfies the designed requirement of tensile strength over 2000 MPa and elongation over 10%. The microstructure characterization indicates that this ultrahigh-strength steel consists of nanomicrostructures including lath martensite, filmlike retained austenite, and dispersive Nb-containing carbides. The effect of tempering time on the mechanical properties is analyzed based on microstructures.

In this work, microwave heating curves and microstructural evolution of nanocrystalline Au thin films were studied so the heating behavior of metals could be better understood. Films with different thickness were irradiated by the H and E maximums of microwave in a single-mode cavity. These samples were more efficiently heated by H field than by E field. With the increase of film thickness, the attained highest temperature increased. This phenomenon was compared with the theory of the transmission line analysis. Peaks appearing at the initial stage of the heating curves were also compared with similar heating behaviors observed in metal powder compacts, and the possible mechanisms related to the heating behavior were explored.

The effect of Ag substituting Cu on the structural features of the Cu55Zr45, Cu45Zr45Ag10, and Cu35Zr45Ag20 glassy alloys was studied using the real-space pair distribution and radial distribution functions. The experimental x-ray diffraction data obtained in a synchrotron beam were used to derive pair and radial distribution functions through Fourier transformation processing. These results suggest that a certain degree of medium-range order in this alloy is maintained up to about 2.5 nm distance. It is suggested that the addition of Ag causes formation of a more homogeneous local atomic structure compared with that of a binary Cu–Zr alloy, which could be considered as a reason for the improved glass-forming ability of this alloy.

Microstructures of epitaxial Ca0.33CoO2 thin films, which were grown on m plane and c(0001) plane of α–Al2O3 by the reactive solid-phase epitaxy (R-SPE) method and the subsequent ion-exchange treatment, were investigated in detail by using selected-area electron diffraction, high-resolution transmission electron microcopy, spherical-aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (Cs-corrected HAADF-STEM), and electron energy-loss spectroscopy (EELS). Detailed electron diffraction analyses reveal that the orientation relationships between Ca0.33CoO2 thin film and substrate are and , having an angle of about 43° with for the film deposited on m plane, and and for the film deposited on c(0001) plane though a Ca–Al–O amorphous layer formed between them. CoO seed layer near the interface and residual Co3O4 phase inside the films were observed and identified by HAADF-STEM and EELS in both samples. Such microstructural configuration indicates that the processes of film growth during R-SPE are (i) oxidation of CoO into Co3O4 with residual CoO layer near the interface and (ii) intercalation of Na+ layer into Co3O4 to achieve the layered NaxCoO2 film while forming Na–Al–O amorphous layer at the interface.

We have demonstrated that 30BaO–15TiO2–30GeO2–25SiO2 (BTGS25) glass is a candidate for fiber-type nonlinear optical devices using crystallization of glass matrix. We determined the glass composition is suitable for crystallized fiber using partial substitution of Ge in 30BaO–15TiO2–55GeO2 (BTG55) by Si. The BTGS25 satisfied both thermal stability for fiber drawing and electronic polarizability for nonlinear optical property. After crystallization, the BTGS25 bulk crystallized glass showed surface crystallization behavior with the polar c-orientation of fresnoite phase, which was favorable for large second-order optical susceptibility. Following the results of the bulk glass, we prepared the BTGS25 glass fiber without precipitation of fresnoite crystallites. The BTGS25 crystallized fiber also showed c-oriented surface crystallization of fresnoite and second harmonic generation, which shows that the crystallized fiber is a promising material for fiber-type optical active devices.