Porous TiO2–P2O5 oxide was synthesized by the sol-gel method in the presence of tri-block copolymer (EO)20(PO)70(EO)20 (Pluronic123) in queous solution. The TiO2 nanocrystals with anatase structure precipitated in the as-synthesized TiO2–P2O5 materials at 80°C, considerably lower than that for traditional heat treatment in the solid state, which maintained a stable size of 3.6–4 nm upon calcinations below 500°C. It is believed that P2O5 glass phase prevents the coarsening of TiO2 nanocrystals below 500°C. The mixed oxide exhibited a specific surface area of 170–200 m2/g after calcining in the temperature range of 300–500°C.

The Debye temperature and glass transition temperature of a variety of bulk metallic glasses (BMGs) were determined by acoustic measurement and differential scanning calorimetry, respectively. The relationship between the Debye temperature and glass transition temperature of these BMGs was analyzed, and their observed correlation was interpreted in terms of the characteristics of the glass transition in BMGs.

Sodium ion-conductive silicon nitride ceramic with Na2O–Al2O3–SiO2 glass as the grain boundary phase was fabricated by adding Na2CO3, Al2O3, and SiO2 as sintering additives. The electrical conductivity was two and four orders of magnitude higher than that of Si3N4 ceramic with Y2O3 and Al2O3 additives at 100 and 1000°C, respectively. This result clearly indicates that ionic conductivity can be provided to insulating structural ceramics by modification of the grain boundary phase without dispersion of conductive particles.

Crystalline CuO and Cu2O nanowires with an average diameter of about 10 nm and lengths of several tens of microns were successfully synthesized, depending on synthesis conditions, using precursor Cu(OH)2 nanowires as templates. The crystallinity, purity, morphology, and structural features of the as-prepared nanowires were characterized by powder x-ray diffraction, selected-area electron diffraction, and high-resolution transmission electron microscopy. The results showed that the precursor polycrystalline Cu(OH)2 nanowires served as both reactants for the growth of CuO and Cu2O nanowires, and as templates controlling the size and shape of the resulting nanowires.

Silicon nitride (Si3N4) whiskers were synthesized via a carbothermal reduction and nitridation process from silica-containing natural substances, such as volcanic ash, diatomaceous earth, white sand, and rice hull, using the flux effect of cryolite. It was clarified that the volcanic ash, whose Fe2O3 content contributed to the formation ratio of the α-type, was suitable as a raw material for the synthesis of Si3N4 whiskers. Fe2O3, Al2O3, and TiO2 contributed to the growth in the whisker-axis direction by the formation of droplets inducing the vapor-liquid-solid mechanism. CaO and MgO led to an increase in the diameter of the whiskers by vapor-solid and vapor-liquid-solid mechanisms, and the Fe2O3 content was the highest in the volcanic ash, whose Fe2O3 content was the highest among the natural substances.

Activated carbon fiber/carbon aerogel (ACF/CA) composites were fabricated by gelling a mixture of ACF and resorcinol and furfural, followed by supercritical drying of the mixture in isopropanol. The product then went through carbonization in a nitrogen atmosphere. The fabrication conditions, such as the mass content of R–F, the content of the ACF added, and the gelation temperature, were explored. The textures and pore structures of the ACF/CA composites thus obtained were characterized using transmission electron microscopy, scanning electron microscopy, and a surface area analyzer. The mechanical properties of the samples were assessed primarily through compressive tests. The experimental results indicated that the added ACF disperses uniformly in the resulting ACF/CA composites. The carbon matrix of the ACF/CA composites also consisted of interconnected carbon nanoparticles with sizes in the range of 20 to 30 nm. The ACFs can reinforce the related carbon aerogels when they originally have low mass density and are weak in mechanical strength. When large amounts of ACF were added to the composites, the micropore area and micropore volume of the composites increased, but their external surface area decreased. The mesopore volumes and the related diameters and mesopore size distributions of the ACF/CA composites were mainly affected by the mass density of the composites. The micropore sizes of all the composites were sharply concentrated at about 0.5 nm.

Boron nitride (BN) nanocrystals with explosion (E) phase were prepared by a novel laser-assisted materials fabrication, i.e., pulsed-laser-induced liquid (acetone)/solid (hexagonal boron nitride bulk) interfacial reaction at normal temperature and pressure. Typical diameters of these synthesized quasi-spherical BN nanocrystals were in the range of 30 to 80 nm. Transmission electron microscopy, x-ray diffraction, and Fourier transformed infrared spectroscopy were used to identify the morphologies and structures of the synthesized nanocrystals. Additionally, we proposed the formation mechanism of cubic-BN and E-BN nanocrystals upon pulsed-laser-induced liquid/solid interfacial reaction, in which both liquid and solid were simultaneously involved.

Improvements in the tribological properties of pure aluminum and “aeronautical” alloy AA7075-T651 were obtained by oxygen-ion implantation [(0.7 to 5) × 1017 O/cm2, 30 keV] using our pulsed electron cyclotron resonance plasma source. This oxygen plasma source ion implantation process produced oxide nanoprecipitates that enhanced the hardness up to three times in the surface layer and caused reductions in the scratch depths and the friction coefficients by similar factors. A spectrum of tribological properties was obtained depending on temperature and ion dose. Temperature measurement and control were obtained through an integrated thermocouple and by changing the duty-cycle of the microwave source. The oxygen content and the depth-resolved chemical composition were measured and optimized using x-ray photoelectron spectroscopy (XPS) combined with Ar-ion etching. The tribological properties were investigated by (i) depth-sensing nanoindentation for hardness and Young's modulus, (ii) scratching and scratch-depth measurement via atomic force microscopy (AFM), and (iii) friction force measurements using AFM. Low-temperature (≤160°C) implantations with optimal O-ion doses produced, in both pure and alloyed Al, an approximately 50-nm-thick, smooth, and extremely fine-grained metal–alumina nanocomposite. The resulting surface was hard and stiff but nonbrittle and displayed high scratch resistance and low friction. High-temperature (~430°C) implantation had different effects on pure Al and AA7075. On pure Al, it produced a very hard but brittle Al2O3 layer for which yield points (displacement excursions) were observed at critical load values in the nanoindentation force–displacement curves. On AA7075, XPS chemical profiling revealed an effect of extreme Mg surface segregation and complete Al surface depletion; MgO crystallites formed a rather rough but surprisingly thick layer (>100 nm). The resulting AA7075 surface showed a hardness increase that was substantial but slightly smaller than that obtained at low temperature.

We describe a vapor-phase route to the controllable synthesis of indium oxide micro-and nanopyramids on the silicon wafer via selective epitaxial vapor-solid growth by a methane-assist thermal reduction method. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy revealed that the pyramids were cubic single crystals with a tetragonal symmetry. The size, morphology, and density of pyramids could easily be controlled by tuning reaction parameters. The method has good compatibility with other procedures involved in the microfabrication processes. Laterally grown indium oxide nanorods on the silicon wafer were also prepared via a vapor-liquid-solid mechanism. Those crystalline In2O3 nanorods were about 100 nm in diameter and 1 μm in length. The as-synthesized indium oxide nanopyramids and nanorods could offer novel opportunities for both fundamental research and technological applications.

Ribbon and bulk nanocrystalline body-centered-cubic (bcc) (Fe,Co) alloys exhibiting good soft magnetic properties were synthesized in Fe71.5-xCoxB13.5Si10Nb4Cu1 system by the simple production processes of melt-spinning or casting and annealing. The glass-type alloys were formed in the Co content range below 30 at.%. These glassy alloys crystallized through two exothermic reactions. The first stage was due to the precipitation of nanoscale bcc-(Fe,Co) phase with a grain size of about 10 nm, and the second stage resulted from the decomposition of the remaining amorphous phase to α–(Fe,Co), (Fe,Co)2B, (Fe,Co)23B6, (Fe,Co)3Si, and (Fe,Co)2Nb phases. The glass transition temperature increased from 820 to 827 K with increasing Co content from 5 to 20 at.%, while the supercooled liquid region decreased slightly from 37 to 30 K because of the nearly constant crystallization temperature. By choosing the 10 at.% Co-containing alloy, we produced cylindrical glassy alloy rods 1.0 and 1.5 mm in diameter by copper mold casting. The subsequent annealing for 300 s at 883 K corresponding to the temperature just above the first exothermic peak caused the formation of nanoscale bcc-(Fe,Co) structure. The bcc-(Fe,Co) alloy rods exhibited good soft magnetic properties of 1.26 T for saturation magnetization and 5.0 A/m for coercive force, which were comparable to those for the corresponding bcc-(Fe,Co) alloy ribbon. The nanocrystalline alloy in a bulk form is encouraging for future use as a new type of soft magnetic material that requires three-dimensional shapes.

Polycrystalline SiC samples hot pressed with aluminum, boron, and carbon sintering additions (ABC-SiC) were characterized using transmission electron microscopy. The study focused on the effects of high-temperature treatment on microstructure. Three temperatures, at which considerable microstructural changes took place, were found to be critical. At a threshold temperature of approximately 1000°C, 1-nm-wide, amorphous intergranular films started to crystallize. At approximately 1300°C, lattice diffusion in SiC grains resulted in nanoprecipits, which could diffuse into grain boundaries and significantly altered composition. Quantitative microanalysis revealed doubled Al content in intergranular films after annealing at 1300°C. Except for crystallization in intergranular films and nano-precipitation in matrix grains, microstructure remained stable until 1600°C, when microstructural changes with volatile features occurred. A brief holding at 1900°C brought marked changes in microstructure, including structural change in intergranular films, dissolved nanoprecipitates, unit cell dilation, and cracking. The results indicate that ABC-SiC is highly promising in structural applications at up to 1500°C.

The use of the glass slag method in the extraction of rare earth from La–Ni alloys was studied. X-ray diffraction and electron probe microanalysis studies revealed that the La–Ni alloys produced by the glass slag method using boron trioxide consisted of Ni and Ni3B phases. No La-containing phase such as the LaNi5 phase and the La oxide phase was found in the resultant alloys. The chemical analyses confirmed that the La content in the alloys produced by the glass slag method was very limited. However, the glass slag materials contained a large amount of lanthanum. The La in the La–Ni alloys was successfully extracted by the glass slag method using boron trioxide.

Composite Ba0.6Sr0.4TiO3/MgO thin films with 60% tuning and tan [H9254] of 0.007 at 2 GHz were deposited using metal organic decomposition inks by spin coating on single crystal MgO substrates. The films with approximately 1 mol% MgO in Ba0.6Sr0.4TiO3 had a better tuning/loss ratio than either the 0 or the 10 mol% MgO substituted films. Crystalline Ba0.5Sr0.5TiO3 films were produced on both MgO and alumina substrates by inkjet printing of metalorganic precursors with subsequent thermal decomposition followed by annealing at 900°C. Barium strontium titanate lines as narrow as 100 μm were printed on the alumina substrates. The inkjet-printed films were predominantly (100) oriented on MgO and (110) oriented on alumina. The crystalline quality of the inkjet-printed films was improved by annealing at 1100°C for 3 h in oxygen. Both the printed and the spin-coated films had smooth surfaces (300 Å root-mean-square roughness) as required for subsequent deposition of high-resolution metal electrodes. An inkjet-printed Ba0.5Sr0.5TiO3 film (3500 Å) on MgO annealed at 1100°C had 20% tunability of the dielectric constant (ε) at 9.1 V/μm direct current bias and tan δ < 0.002 at 1 MHz.

Electrochemical codeposition of diamond particles and refractory metal hydroxide films was conducted by combining electrophoretic deposition and anodic dissolution. Anodic corrosion of metal proceeded under the influence of iodide ions, and then metal ions were released to the solvent. Positively charged diamond particles were suspended in the solvent and electrophoretically deposited on the cathode surface at the same time as electrochemical deposition of the metal ions. As a result, diamond dispersed metal hydroxide film was produced. The diamond content of the film was easily controlled by varying the quantity of suspension in the solvent. This codeposition mechanism is investigated in detail.

Polystyrene (PS) core–TiO2 shell composite particles and TiO2 hollow spheres were fabricated using the liquid phase deposition (LPD) method. Composite particles were prepared using PS particles as templates. Calcination of the composite particles resulted in TiO2 hollow spheres. Uniform TiO2 hollow spheres were obtained when the reaction time of the LPD process was between 4 and 8 h. Furthermore, we fabricated TiO2 hollow spheres whose inner surfaces were functionalized by Pt particles after platinized PS particles were used as templates. The Pt particles were immobilized on the inner surfaces of the hollow spheres.

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.

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.

The load-transfer efficiency of reinforcement, in cylindrical forms in metal-matrix composite (MMC), was analyzed based on the shear-lag model. Both the geometric shape and alignment of reinforcement were considered. The stress transferred to a misaligned whisker was calculated from differential equations based on the force equilibrium in longitudinal and transverse directions. A new parameter, defined as effective aspect ratio, was used to indicate the load-transfer efficiency of misaligned reinforcement. The effective aspect ratio was formulated as a function of aspect ratio and misorientation angle of reinforcement in MMC. A probability density function of misorientation distribution was used to estimate the strengthening effect of all misaligned whiskers distributed in the matrix. Considering the contributions of both effective aspect ratio and misorientation distribution on load-transfer efficiency, a generalized shear-lag model was proposed to explain the mechanical anisotropy of discontinuous reinforced MMC.

Multidomained heteroepitaxial WO3 films were grown on Si(100) substrates using a (111)-oriented BaF2 buffer layer at the WO3–Si interface. The 30-nm-thick BaF2 layer, grown by very low rate molecular-beam epitaxy, consisted of four equivalent crystalline domains oriented about the BaF2[111] axis, which provided templates for heteroepitaxial WO3 film growth. The WO3 films were grown by electron cyclotron resonance oxygen plasma-assisted electron beam evaporation of a WO3 source, and the temperature range was varied between 25°C and 600°C. At an optimal deposition temperature of approximately 450°C, monoclinic-phase WO3 films were produced, which consisted of coexisting (002), (020), and (200) in-plane orientations with respect to the BaF2(111)/Si(100) substrate. During growth, an interfacial barium tungstate (BaWO4) reaction product formed at the WO3–BaF2 interface. The {112} planes of this BaWO4 layer also have a multidomained heteroepitaxial orientation with respect to the BaF2(111) buffer layer. Postdeposition annealing experiments in air for 24 h at 400°C indicated that the heteroepitaxial BaWO4 and WO3 layers remain stable. A thermodynamic argument is used to explain the BaWO4 interfacial reaction during initial growth stages, and kinetically limited diffusion processes through the BaWO4layer coupled with lattice matching across the WO3–BaWO4 interface are proposed to be responsible for the formation of stable WO3 films at later growth stages.

The polarization reversal process in a rhombohedral ferroelectric ceramic material was investigated using field-induced strain measurements and texture development. Special attention was focused on the difference in the field-induced strains between the first quarter cycle and subsequent loading conditions. Results show that the initial field-induced strain is about twelve times greater than the subsequent strain, which immediately suggests that mechanisms involved in these conditions during the polarization reversal process are different. The difference in the magnitude of field-induced strain is discussed in terms of 180° and non-180° domain reorientation processes.