The tensile deformation of anisotropic porous copper with unidirectionally oriented cylindrical pores was investigated by an acoustic emission method. In the loadings parallel and perpendicular to the orientation direction of the pores, many cracks are formed after yielding and they strongly affect the deformation. The formed cracks rapidly grow and connect with each other near the peak stress of the stress–strain curve, thereby leading to final fracture. Crack formation is easier under perpendicular loading than under parallel loading, because high stress concentration and stress triaxiality occurs around the pores. As a result, the strength and elongation for perpendicular loading are much smaller than those for parallel loading. Furthermore, in the case of perpendicular loading, the localized deformation around pores drastically decreases the plastic Poisson's ratio. These results indicate that a porous copper macroscopically behaves as a semibrittle material under perpendicular loading, while the porous copper exhibits ductility under parallel loading.

To fabricate graded-index optical elements by silver staining, we investigated the behavior of ion incorporation in aluminoborosilicate glasses, in which the contents of Al2O3 and Na2O were the same (in mol%). The amount of silver incorporated into the aluminoborosilicate glasses by the staining at 320 °C for 12 h was 5 to 10 times larger than that incorporated into the soda-lime silicate and borosilicate glasses. The diffusion depth of the incorporated silver ions was approximately 80 μm, which was also much deeper than that of the soda-lime silicate and borosilicate glasses. The coloration of the glasses was suppressed, particularly for the glass with the low content of Na2O. The concentration of the incorporated silver ions at the glass surface was 2 × 1021 atom/cm3 for the 37.5SiO2·25Al2O3·25Na2O·12.5B2O3 glass, corresponding to the replacement of sodium ions (20%). The refractive indices near the stained surfaces increased by 0.04 to 0.06. These values were comparable with those of the soda-lime silicate and borosilicate glasses.

The synthesis of hexagonal aluminum nitride (AlN) nanoparticles and nanowhiskers by using direct nitridation of aluminum powders is presented in this work. After mixing aluminum powders with carbon and silica (derived from rice bran ashes) at a cryogenic temperature, the homogeneous mixture was heat treated/examined in a differential scanning calorimeter/tube furnace under N2 atmosphere. Under a maximum temperature of 1450 °C in N2 atmosphere, the as-milled aluminum-carbon-silica powder mixtures transformed completely into AlN nanoparticles and nanowhiskers with a trace of graphite. The formation mechanisms for AlN nanoparticles and nanowhiskers are discussed.

As-deposited ZnO/diamondlike carbon (DLC) was prepared using the laser ablation technique on ZnO/C targets, and in situ oxidized ZnO/DLC was prepared by using the same technique, but with the presence of oxygen on Zn/C targets. Transmission electron microscopy showed that ZnO/DLC films were obtainable by using both methods, but only in situ oxidized ZnO/DLC films showed the ultraviolet absorption at ˜370 nm. In situ oxidized films are highly sp3-bonded and rougher than as-deposited films, but as-deposited films are mechanically harder, stiffer, and have higher adhesion strength than in situ oxidized films. X-ray photoelectron spectroscopy revealed that a lower fraction of SiC, but a higher fraction of sp3 bonding was formed in the in situ oxidized ZnO/DLC. This hinted that the presence of oxygen might have scattered the plume’s expansion and reduced the energy possessed by the ions, thus reducing the graphitization and the formation of SiC in DLC matrix. Hence, by altering the deposition mechanism during laser ablation, ZnO/DLC films with modified material properties can be tailored.

We have developed dye-sensitized nanocrystalline CdS and ZnS solar cells (DSSCs) based on crystal violet, methylene blue, and fluorescein photosensitizers. Nanocrystalline CdS and ZnS were synthesized by a green synthesis method using starch as the capping agent. Characterization of nanocrystalline CdS and ZnS was carried out by optical absorption and x-ray diffraction. The results indicate that CdS and ZnS prepared by this method may be used as photoelectodes in photo-electro-chemical energy conversion systems. DSSCs have been built and their photocurrent, open-circuit voltage, fill factor, and efficiency have been measured under direct sunlight illumination (1000 Wcm−2). The efficiency of the cells made from dye-CdS was much higher than that of the cells made from dye-ZnS. This can be attributed to the particle size effect. Among the prepared dye-sensitized solar cells, a DSSC based on fluorescein dye as the photosensitizer produced the highest overall light solar energy to electricity conversion efficiency.

Zr52.5Cu17.9Ni14.6Al10Ti5 bulk metallic glass (BMG) alloy samples in both rod and plate geometry were prepared. Different free volume states were obtained through thermal treatment. The plastic deformation ability of the BMGs was investigated through both a three-point bending test and compression test. The three-point bending results reveal the important role of free volume content on the formation of multiple shear bands, as the shear band propagation can be efficiently stopped due to the existence of the stress gradient from the surface to the neutral plane. In compression, the sample size rather than free volume controls the shear banding behavior.

Previous computer simulations of multiple 10 keV Si cascades in 3C–SiC demonstrated that many damage-state properties exhibit relatively smooth, but noticeably different, dose dependencies. A more recent analysis of these damage-state properties, which includes additional data at low and intermediate doses, reveals more complex relationships between system energy, swelling, energy per defect, relative disorder, elastic modulus, and elastic constant, C11. These relationships provide evidence for the onset of both defect clustering and solid-state amorphization, which appear to be driven by local energy and elastic instabilities from the accumulation of defects. The results provide guidance on experimental approaches to reveal the onset of these processes.

The thin film electrolyte known as Lipon (lithium phosphorous oxynitride) has proven successful for planar thin film battery applications. Here, the sputter deposition of the amorphous LiPON electrolyte onto more complex 3D structures is examined. The 3D structures include off-axis alignment of planar substrates and also 10–100 μm arrays of pores, columns, and grooves. For magnetron sputtering in N2 gas at 2.6 Pa, the Lipon film deposition is not restricted to be line-of-sight to the target, but forms conformal and dense films over the 3D and off-axis substrates. The deposition rate decreases for areas and grooves that are less accessible by the sputtered flux. The composition varies, but remains within the range that gives sufficient Li+ ionic conductivity, 2 ± 1 μS/cm.

We demonstrated the growth of indium nitride (InN) nanowires on Si(111) substrates by metalorganic chemical vapor deposition without the use of any intermediate GaN or AlN buffer layer. The InN nanowires were grown by forming the Au + In droplets and In droplets on the Au- and In-coated Si substrate. The growth conditions such as chamber pressure, chamber temperature, reaction gas flow rate, and carrier gas flow rate were optimized to yield nanowires free from contamination. Depending on the growth parameters different growth regimes for the InN nanowires were identified. The strength of self-catalytic route has been highlighted. The morphology and microstructures of samples were characterized by x-ray diffraction and scanning electron microscopy (SEM). The transmission electron microscopy and SEM investigations showed that the InN nanowires are single crystals with diameters ranging from 40 to 400 nm, and lengths up to 3 µm. Photoluminescence spectra of the InN nanowires showed a strong broad emission peak at 0.77 eV.

Images of synchro-Shockley partial dislocation arrangements in the Laves phases NbCr2 and HfCr2 have been obtained by high-resolution transmission electron microscopy. The analysis of the stacking sequences around these arrangements revealed the role of the constituting partial dislocations in enabling the polytypic C14 → C36/6H phase transformation in both alloys. The synchro-Shockley partial dislocations occur in and move through the crystals mainly as dipoles of partials of opposite signs, leading to—as compared to isolated partials—strain fields of lesser extent. In NbCr2 a single, probably quenched synchro-Shockley partial dislocation dipole, consisting of two partials with Burgers vectors of opposite sign, was identified. The ordered passage of a series of this type of line defects brings about the C14 → C36 transformation. In HfCr2 a complex synchro-Shockley partial dislocation configuration was revealed. It can be regarded as an “antiphase boundary” between two C36 domains. It is likely that this defect structure had formed by impingement of two domains of C36 growing perpendicular to the stacking direction by glide of synchro-Shockley partial dislocation dipoles.

The formation of Zn whiskers threatens the reliable operation of electronic equipment with an electrical shorting hazard. As with tin whiskers (much more intensively researched than Zn whiskers), the mechanism of formation is still not clear. This work investigated the Zn whisker growth mechanism for an electroplated Zn coating above a carbon steel substrate from a raised floor tile. Iron–zinc (Fe–Zn) intermetallic and Zn oxides were identified by x-ray diffraction analysis (XRD) and electron probe microanalysis (EPMA). Fe–Zn intermetallic compounds formed on the surface of the Zn layer in addition to the interface between the Zn coating and the steel substrate. Zn oxides formed primarily on the surface of the Zn coating. Fe–Zn intermetallic compounds and Zn oxide formation can be the source of a residual stress that promotes Zn diffusion to the surface of electroplated Zn coating, resulting in the formation of Zn whiskers.

The effect of the presence of diamondlike carbon coatings deposited on (100) Si substrates on the deformation mechanisms operating in the silicon substrate during contact loading have been investigated by both cross-sectional transmission electron microscopy and modeling of the stresses generated beneath the indenter tip. The observed subsurface microstructures were correlated to the Tresca shear stress and the hydrostatic stress generated in the silicon substrate beneath the indenter tip. The presence of the coating altered the stresses generated in the substrate, and changed the deformation mechanism from one of principally phase transformation in uncoated Si to predominantly dislocation motion in the silicon substrate for the diamondlike C–Si system. The magnitude and distribution of the shear and hydrostatic stresses in the substrate were found to depend on both the indentation load and the thickness of the coating. Furthermore, the observed width of deformation, parallel to the interface, which was found to increase with coating thickness, was correlated to the wider distribution of the Tresca shear stress in the substrate brought about by the presence of the coating.

Sn-xCu/Ni-yCo (x = 0.2–1.0 wt%, y = 10, 20, 40 at.%) interfacial reactions at 250 °C are examined in this study. Sn-Cu alloys are promising lead free solders, and Ni-Co alloys are the potential diffusion barrier layer materials in flip chip packaging. The Co and Cu effects on the Sn-Cu/Ni-Co interfacial reactions are examined. When the Co addition is 10 at.%, the reaction phases are the Ni3Sn4 and Cu6Sn5 phase, and Sn-Cu/Ni-10at.%Co interfacial reactions are similar to those of Sn-Cu/Ni. When the Co addition is 20 at.%, the CoSn2 phase is formed, and the reaction path is Sn-Cu/Ni3Sn4/CoSn2/Ni-20at.%Co. When the Co addition is 40 at.%, only Sn-Co binary phases are formed (CoSn2 and CoSn3), and Sn-Ni binary phases are not formed. The Cu6Sn5 phase is not formed until the Cu content is higher than 0.7 wt%. The Cu concentration effect is the main drawback of using Ni as the diffusion barrier layer material and the Sn-Cu solders. The Cu concentration effect of the Sn-Cu/Ni-Co interfacial reactions is not as pronounced as that of Sn-Cu/Ni.

SnO2@carbon nanofibers were synthesized by a combination of electrospinning and subsequent thermal treatments in air and then in argon to demonstrate their potential use as an anode material in lithium ion battery applications. The as-prepared SnO2@carbon nanofibers consist of SnO2 nanoparticles/nanocrystals encapsulated in a carbon matrix and contain many mesopores. Because of the charge pathways, both for the electrons and the lithium ions, and the buffering function provided by both the carbon encapsulating the SnO2 nanoparticles and the mesopores, which tends to alleviate the volumetric effects during the charge/discharge cycles, the nanofibers display a greatly improved reversible capacity of 420 mAh/g after 100 cycles at a constant current of 100 mA/g, and a sharply enhanced reversible capacity at higher rates (0.5, 1, and 2 C) compared with pure SnO2 nanofibers, which makes it a promising anode material for lithium ion batteries.

Nitrogen-doped titania with a unique two-level hierarchical structure and visible light photocatalytic activity is reported. Thus, nitrogen-doped titanium oxide microrods decorated with N-doped titanium oxide nanosheets were synthesized by a hydrothermal reaction in NH4OH and postcalcination. During the calcination, the in situ incorporation of nitrogen atoms of ammonium ion into titania lattice was accompanied by the structural evolution from titanate to anatase titania. The morphological and structural evolution was monitored by scanning electron microscopy (SEM), x-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TGA/DTA), Raman, Fourier transform infrared (FTIR), x-ray absorption near edge structure (XANES), x-ray photoelectron spectroscopy (XPS), and adsorption isotherms. The N-doping brought visible light absorption, and the material exhibited high photocatalytic activity in the decomposition of Orange II under visible light irradiation (λ ≥ 400 nm), especially when it was loaded with 1 wt% Pt as a cocatalyst.

4H-silicon carbide (SiC) wafers were annealed at 1300 and 1600 °C for 30 min and 60 min in a conventional and purified Ar atmosphere. The surface roughness before and after annealing was evaluated by atomic force microscopy. The surface roughness before annealing was approximately 2.37 nm in root mean square. The roughness, after annealing for 30 min at 1300 and 1600 °C in a conventional Ar furnace, was increased to 4.53 and 14.9 nm, respectively. The roughness, after annealing for 60 min, was 5.01 and 19.1 nm, respectively. In this study, the G3 grade Ar gas (99.999%) was supplied in the conventional furnace tube. When the Ar gas was purified to an impurity concentration of less than 1 ppb, and it was supplied in the leak-tight furnace tube, the roughness after 30-min annealing improved 4.27 and 6.93 nm at 1300 and 1600 °C, respectively. The roughness after 60-min annealing was also reduced to 3.54 and 9.28 nm, respectively. We assume that a significant reduction of H2O concentration in the annealing atmosphere might play an important role in suppressing surface roughening of SiC during high-temperature annealing.

Nanoindentation and the viscous-elastic–plastic (VEP) model developed by Oyen and Cook for lightly filled thermoplastic polymer composites were used to characterize the elastic modulus, hardness, and viscoelastic response of a new high elastic modulus dental resin composite. The VEP model was used because loading rate studies indicated a viscous component in the loading/unloading response of our highly filled, thermosetting acrylic resin composites. Increasing the volume fraction of our high modulus filler increased the elastic modulus and hardness and decreased the viscous response in our composites. Coupling the filler and resin matrix with a commercial coupling agent like Metaltite or MPTMS (3-methacryloxypropyltrimethoxysilane) that ionically bonds to the filler and covalently bonds to the matrix decreases the viscous response and increases the hardness of the composite. The coupling agents did not affect the elastic modulus. The ability of the VEP model to predict load–displacement trajectories and the correlation of the elastic modulus and hardness values determined from the VEP model with those from the direct continuous stiffness measurement mode nanoindentation measurements indicate that the VEP model can be extended to highly filled, thermosetting systems. This is valuable since the potential to predict elastic, plastic, and viscous contributions to behavior should be valuable in the design and understanding of future highly filled resin composite systems.

This investigation elucidates stress evolution in situ in tin strips under electromigration using synchrotron radiation x-ray. Minute variations in stress are determined precisely using intense x-rays. Back stresses gradient with the values of 5.5 and 16.5 MPa/cm, which are induced by the current densities of 1 × 103 and 5 × 103 A/cm2, respectively, are measured directly. The effective diffusivities that include both grain and lattice diffusion at various current densities are determined. The Joule heating is observed, ranging from 5 to 15 °C, according to various current densities passed through the stripes. Results of this study suggest that the protective oxide layer on the surfaces significantly influences the kinetics of stress evolution.

YFeO3/TiO2 heterojunction semiconductors were prepared by the milling–annealing method. Effects of structure and surface phase by annealing temperature and TiO2 weight content were investigated. The physical and photophysical properties of heterojunction semiconductors were characterized by x-ray diffraction (XRD), UV-visible diffraction (UV-vis/DRS), and x-ray photoelectron spectroscopy (XPS), N2 adsorption. YFeO3 is presented as p-type semiconductor and disperses on the surface of n-type TiO2 to constitute a heterojunction composite. Results show that the presence of p–n junction not only has visible light harvesting but potential force for hole–electron pair separation. A preliminary investigation of photodegradation effect on Orange II showed that YFeO3/TiO2 heterojunction semiconductors exhibited better photocatalytic properties than the single phase of YFeO3 or TiO2. The ideal heterojunction semiconductor composition was ω (TiO2) = 0.9 sample annealed at 600 °C. The mechanism of the electric-field-driven electron–hole separation initiated by the chemically bonded p–n heterojunction and enhanced photocatalytic activity were discussed.

The densification behaviors of two silicon nitride nanopowder mixtures based respectively on α-Si3N4 and β-Si3N4 as the major phase constituent were studied by spark plasma sintering. Sintering conditions were established where a low viscous liquid not in equilibrium with the main crystalline constituent(s) stimulated the grain sliding yet did not activate the reprecipitation mechanism that unavoidably yields grain growth. By this way of dynamic grain sliding full densification of silicon nitride nanoceramics was achieved with no noticeable involvement of α- to β-Si3N4 phase transformation and grain growth. This processing principle opens the way toward flexible and precise tailoring of the microstructures and properties of Si3N4 ceramics. The obtained silicon nitride nanoceramics showed improved wear resistance, particularly under higher Hertzian stresses.