Thermal and photo-optical properties of azoxybenzene/alkyloxy-azobenzene containing chiral dimesogens are presented. Alkyloxyazobenzene containing dimesogenic materials exhibited two kinds of smectic A phases. Photoirradiation at temperatures exhibiting smectic phases of pure materials in azobenzene linked dimesogens resulted in formation of the isotropic phase, and this was systematically studied at different liquid crystalline temperatures. The efficacy of these compounds as a dopant in the glassy liquid crystalline material was also explored. Increasing concentration to 4 wt%/5 wt% in azobenzene/azoxy-benzene derivatives caused a dramatic red-shift in the wavelength of reflected light by the host cholesteric glassy liquid crystal. Photo-isomerization of these dopants led to a blue-shift of the reflected light, and this effect could be used to tune the light reflectivity of these mixtures over the visible region.

The effect of the film thickness on the phase transformations encountered in sputtered titanium-nickel (TiNi) shape-memory films due to thermal cycling in the temperature range of −150 to 150 °C was examined in the context of electrical resistivity (ER) measurements. A hysteresis in the ER response was observed for film thickness greater than 300 nm. This phenomenon is characteristic of shape-memory materials and is attributed to the rhombohedral (R) phase produced during cooling from the high-temperature cubic austenite phase to the low-temperature monoclinic martensite phase. The decrease of the TiNi film thickness below 300 nm resulted in a smaller ER hysteresis, leading eventually to its disappearance for film thickness less than ∼50 nm. The results indicate that spatial constraints introduced by the film surface and film/substrate interface generate a resistance force, which prevents lattice distortion and twinning. The inhibition of these mechanisms, which control self-accommodation R-phase transformation, leads to the suppression and eventual disappearance of the shape memory effect for film thickness less than ∼100 nm.

In this paper, we derive corrected analytical expressions for calculating the hardness and modulus by the two-slope method. This method relies on the determination of the slopes of the loading and unloading curves rather than the indenter displacement as an input. These expressions take into account the correction factor α in the fundamental relations among contact stiffness, elastic modulus, and contact area, which is frequently forgotten or misused in the literature. It is shown that these corrected expressions allow measurements of the hardness and modulus in very good agreement with the commonly used technique based on the determination of the contact area. Additionally, the correction factor α can be easily determined if Young's modulus of the material is known.

Silica/titania composite particles were prepared by co-oxidation of titanium-tetra-isopropoxide and hexamethyldisiloxane in a co-flow diffusion flame reactor. The influence of precursor composition on product powder characteristics was studied by x-ray diffraction, nitrogen adsorption, electron microscopy, elemental mapping, and energy-dispersive x-ray analysis. The flame temperature was measured by Fourier transform infrared spectroscopy. The evolution of composite particle morphology from ramified agglomerates to spot- or fully coated particles was investigated by thermophoretic sampling and transmission/scanning electron microscopy. At 40–60 wt% TiO2, particles with segregated regions of silica and titania were formed, while at 80 wt% TiO2 rough silica coatings were obtained. Rapid flame-quenching with a critical flow nozzle at 5 cm above the burner nearly halved the product particle size, changed its crystallinity from pure anatase to mostly rutile and resulted in smooth silica coatings on particles containing 80 wt% TiO2.

Purified single-walled nanotubes (SWNTs) were dispersed in an epoxy polymer and subjected to uniaxial compressive loading. The orientation and stress in the nanotubes were monitored in situ using polarized Raman microscopy. At strains less than 2%, the nanotubes reorient normal to the direction of compression, thereby minimizing the local strain energy. Above 2% strain, the Raman peak shift reaches a plateau. A new analytical model, which approximates the SWNT reorientation by varying the aspect ratio of a representative spheroid, predicted the rotation behavior of nanotubes under load. The results of this model suggest that the observed plateau of the Raman peak shift is caused by both polymer yielding and interfacial debonding at the ends of nanotubes.

Wavelength dependence was observed in the ultraviolet (UV) irradiation-assisted crystallization of alkoxy-derived ZrO2 thin films. The surface grains of thin films deposited on Si(100) substrates became enlarged by UV irradiation using an ultrahigh-pressure mercury lamp. The crystallinity of thin films deposited on Si(100) substrates was improved by UV irradiation using a low-pressure mercury lamp. The reaction using the ultrahigh-pressure mercury lamp depended on the substrate type.

Sn–8Zn–3Bi solder paste and Sn–3.2Ag–0.5Cu solder balls were reflowed simultaneously on Cu/Ni/Au metallized ball grid array (BGA) substrates. The correlation between microstructural evolution and the electrical resistance of the joints under various testing conditions of reflow cycles and heat treatment was investigated. The electrical resistance of the Sn–Ag–Cu joints without Sn–Zn–Bi was also conducted for comparison. The average resistance values of Sn–Ag–Cu and Sn–Ag–Cu/Sn–Zn–Bi samples changed, respectively, from 7.1 (single reflow) to 7.3 (10 cycles) mΩ and from 7.2 (single reflow) to 7.6 (10 cycles) mΩ. Furthermore, the average resistance values of Sn–Ag–Cu and Sn–Ag–Cu/Sn–Zn–Bi samples changed, respectively, from 7.1 (aging 0 h) to 7.8 (aging 1000 h) mΩ and from 7.2 (aging 0 h) to 7.9 (aging 1000 h) mΩ. It was also noticeable that the average resistance values of Sn–Ag–Cu/Sn–Zn–Bi samples were higher than those of Sn–Ag–Cu samples in each specified testing condition. The possible reasons for the greater resistance exhibited by the Sn–Zn–Bi incorporated joints were discussed.

Silicon carbide (SiC) ceramics have good wear resistance but poor friction properties under dry sliding conditions. To lower the friction of SiC, a novel porous carbon material called rice bran carbon (RBC) was added into SiC to make SiC/RBC composite ceramics. The SiC/RBC composites were prepared by mixing one of three kinds of RBC powders having different particle sizes and a fine SiC doped with Al4C3 and B4C additives and sintering at 1600 °C for 5 min by a pulse electric current sintering (PECS) method. The mechanical and tribological properties of the SiC/RBC composites were evaluated and compared with those of monolithic SiC, monolithic RBC bulk material, and SiC/graphite composite. The SiC/RBC composites not only had superior fracture strength (3–4 times as high as that of the monolithic RBC material) but also showed low friction coefficients (around 0.25) and high wear resistance (at a level of 10−6 mm3 N−1 m−1) when slid against a silicon carbide ceramic counterface during block-on-ring sliding tests under dry conditions. Compared with the conventional SiC/graphite composite, the SiC/RBC composites had higher mechanical strength, lower friction coefficients, and better wear resistance.

Hot-forged Ca3Co4O9 (Co349) ceramics were synthesized using large-grained powders prepared by a flux-growth method, and their thermoelectric properties and degree of grain alignment were evaluated. Neutron-diffraction experiments evidenced the effect of grain size on the development of the c-axis grain alignment. The optimum grain size was around 7 μm in our hot-forging method. The electrical resistivity (ρ) in the direction parallel to the pressed-plane was more reduced at higher degrees of orientation. Since ρ was reduced without lowering the Seebeck coefficient (S), the power factor (PF = S2/ρ) of the Co349 sample was improved and reached 0.8 mW/mK2 at 1073 K using Co349 grains with average size of around 7 μm. The thermal conductivity (κ) in the direction parallel to the pressed-plane slightly increased with the increase of the grain size, however the improvement of PF owing to use of large-grained powder outweighed this negative impact on the κ component of the thermoelectric figure of merit (Z = S2/ρκ).

In this work, the microstructure and oxidation resistance of pure Cu, Cu(0.2 at.% Zr) and Cu(2.5 at.% Zr) alloy films deposited on SiO2/Si by sputtering were explored. Upon annealing, the Zr additives diffused to the free surface and reacted with the residual oxygen in the vacuum system. An additional ZrO2 layer formed and covered the Cu(2.5 at.% Zr) film surface after annealing at 700 °C for 30 min. Simultaneously, of the three films, the Cu(2.5 at.% Zr) film exhibited the highest degree of Cu(111) preferred orientation and the lowest degree of void growth upon annealing. Additionally, the Cu(2.5 at.% Zr) film pre-annealed at 700 °C showed a superior oxidation resistance when annealed at 200 °C in air for 15 min. Microstructure and oxidation resistance of Cu(Zr) alloy films were clearly affected by the ZrO2 layer formed via the segregation of Zr additives, and the connection is discussed.

The goal of this study was to determine the scattering mechanisms and investigate the optoelectronic properties of indium molybdenum oxide (IMO) films. IMO films were deposited from an In2O3/MoO3 target with a weight ratio of 99/1, 95/5 and 90/10 via high-density plasma evaporation at room temperature. Based on the structural, electrical and optical properties, this study proposed that the neutral complex [(2Mo‧In)Oi″]x dominated at high doping content and high oxygen content, whereas ionized complex Mo‧‧‧In Oi″]‧ dominated at low doping level or low oxygen content. Uniform 99/1 IMO films with minimum resistivity of 3.56 × 10−4 Ω cm (corresponding to a mobility of 14.6 cm2V−1s−1 and carrier concentration of 14.3 × 1020 cm−3) and average visible transmittance of ∼85% were produced at an optimum oxygen content of ∼9%. Average optical transmittance exceeding 80% was demonstrated, and a structural change appeared at low oxygen contents.

A series of water-soluble silicon oxide materials was synthesized by the sol-gel reaction of tetramethoxysilane (TMOS)/3-aminopropyltrimethoxysilane (APTMOS) mixtures catalyzed by hydrochloric acid with varying TMOS/APTMOS ratios. Increase in TMOS composition made the products less water-soluble, and the richest TMOS composition for the water-soluble silicon oxide materials was found to be TMOS/APTMOS = 7/3 (mol/mol). Ultraviolet-visible spectroscopy of a 10 wt% aqueous solution of the product with TMOS/APTMOS = 7/3 showed a high transmittance in the visible region. Its infrared spectrum showed an absorptionband attributable to the Si–O bond, and the 29Si dipole decoupled/magic angle spinning–nuclear magnetic resonance spectrum exhibited signals in the regions of T3, Q3, and Q4, indicating a dense siloxane network structure. A peak due to an ordered structure with a 1.76 nm periodicity was observed in the x-ray diffraction profile, and a stripe pattern was observed in the transmission electron microscopy image. These results indicate that the rodlike silicon oxide macromolecules with a 1–2-nm diameter stack parallel. Thus a silicon oxide material with nano-ordered structure was successfully formed and such a structure produced the water solubility.

Considerable amounts of anatase nanocrystals were formed on the (100 − x)SiO2·xTiO2 coatings with x of 16.5 and 25 mol% with boiling water treatment, whereas the formation of anatase nanocrystals was not clearly observed for the coatings with x of 50 and 75 mol%. Despite the lower TiO2 content, the coatings with x of 16.5 and 25 mol% showed higher concentration of Si–O–Ti bonds among the coatings. Thus, the hydrolysis of Si–O–Ti bonds and resultant sites should facilitate the nucleation and growth of anatase nanocrystals. High transparency, high photocatalytic activity, and superhydrophilicity were demonstrated for the anatase nanocrystals-precipitated coatings.

A series of abrasives with various hardness values including monocrystalline and polycrystalline diamond, α- and γ-alumina, zirconia, ceria, and silica were used to examine the concept of chemical-assisted polishing for finishing the (0001), c-plane (basal plane), of sapphire. Diaspore, a monohydrate of alumina, was also evaluated. Atomic force microscopy suggested that the hydrated layer of the c-plane surface was about 1 nm thick. Polishing experiments were designed to determine whether the chemically modified surface hydration layer forms on the basal plane in water. The results indicate that harder abrasives do not necessarily cause faster material removal and better surface finish for similar abrasive particle size. Abrasives with hardness equal to or less than sapphire such as α-Al2O3 and γ-Al2O3 achieved the best surface finish and greatest efficiency of material removal. It is proposed that the (0001) c-plane sapphire surface was modified by water to form a thin hydration layer with structure and hardness close to diaspore. This reaction layer can be removed by an abrasive that is softer than sapphire but harder than the reaction layer. α-Al2O3 was particularly effective. This result is attributed to adhesion between identical reaction layers on the basal planes of the alumina abrasive and the sapphire. This demonstrates that high removal rates and good surface finish can be achieved without costly diamond polishing.

Colloidally stable suspensions are required to fabricate dense samples with uniform microstructure by colloidal processing methods, which necessitate dispersion of ceramic powders in a liquid medium. Aqueous nano ZrO2 suspensions were prepared using polyethylenimine (PEI) as a dispersant. PEI adsorption on nano ZrO2 surfaces was promoted with increasing initial PEI content and suspension pH. Isoelectric point was shifted from pH 7 at 0 wt% PEI to pH 10.4 at 3 wt% PEI. Stable suspensions had mean particle sizes in the range of 100 to 150 nm and sedimentation rates less than0.4 mm/h, as compared to 2–5.5 μm and 10–50 mm/h for unstable suspensions. Samples with 98% relative density were fabricated after sintering at 1300 °C for 4 h from colloidally stable suspensions.

The reaction between Sn–xCu (x = 0.1, 0.3, 0.7, 0.9, and 1.5 wt%) solder alloys and Ni at 260, 280, and 290 °C for 60 s was studied to reveal the effect of Cu content on the composition and morphology of intermetallic compounds (IMCs) formed at the interface between solder and substrate. The results indicated that Cu concentration greatly affects both the composition and morphology of the IMC between the solder and Ni substrate. In particular, when the Cu concentration was less than or equal to0.3 wt%, (CuxNi1−x)3Sn4 IMCs were formed at the interface. When the Cu concentration was 0.7 wt%, large facets type of (CuxNi1−x)6Sn5 were mixed with (CuxNi1−x)3Sn4 in the IMC layer. At Cu concentrations higher than the eutectic one, e.g., 0.9 and 1.5 wt%, stick-shaped (CuxNi1−x)6Sn5 compounds were detected, but the (CuxNi1−x)3Sn4 IMCs disappeared. The formation and growth mechanism of the (CuxNi1−x)6Sn5 compound were analyzed. The evolution tendency of the composition and morphology of the IMCs at the three testing temperatures was found to be the same.