A range of nitrogen-doped amorphous hydrogenated carbon samples (a-C:Nx:H, where x = 3 at.% and x = 7 at.%) have been studied using neutron diffraction, inelastic neutron scattering (INS) and Fourier transform infra-red (FTIR) spectroscopy to obtain detailed information about their atomic-scale structure, particularly the bonding environment of the hydrogen. The results show that the overall atomic scale network structure of the two samples is very similar; however, the hydrogen-bonding sites alter subtly as the nitrogen content of the samples is increased.

Liquidus temperatures (TL) were measured, and primary phases were determined for 50 (from an initial test matrix of 76) compositions within the Al2O3–B2O3–CaO–Na2O–SiO2 glass-forming system and its constituent ternary subsystems. Strong linear correlations have been found between composition and TL for melts within the same primary phase fields. The TL and primary phase data are being used to develop and refine a modified associate species model (ASM). The impacts of Fe2O3, Li2O, NiO, ZrO2, Cr2O3, ZnO, and MnO additions on the TL of two baseline glass compositions are reported. These data are intended as benchmarks for further expansion of the ASM or other silicate melt solution models of nuclear waste glasses.

Growth of such non-superconducting whiskers [Sr2.24Ca0.4Al2Ox, (Ca0.8–0.85Sr0.15–0.1)2CuO3,CuO, or Bi2.44Sr2Ca1.3–2Cu6.9–9.95Al0.35–0.46Ox (Cu-rich whiskers)] formed during the growth of Bi-2212 superconducting whiskers from powder or glassy substrates, is discussed. These whiskers are likely to grow from the bottom end, and there is a tight relationship with the growth of the Bi-2212 whiskers. A general reaction-path model for the whisker growth in the BSCCO system, independent of the type of the catalytic impurity and substrate, is proposed. When whiskers are grown under magnetic fields, up to 10 T, changes in the whisker size, aspect ratio, and morphology are observed.

We systematically introduced defects onto the body of multi-walled carbon nanotubes through an acid treatment, and the evolution of these defects was examined by Raman spectroscopy using different excitation wavelengths. The D and D′ modes are most prominent and responsive to defect formation caused by acid treatment and exhibit dispersive behavior upon changing the excitation wavelengths as expected from the double resonance Raman (DRR) mechanism. Several weaker Raman resonances including D″ and L1 (L2) + D′ modes were also observed at the lower excitation wavelengths (633 and 785 nm). In addition, specific structural defects including the typical pentagon-heptagon structure (Stone–Wales defects) were identified by Raman spectroscopy. In a closer analysis we also observed Haeckelite structures, specifically Ag mode response in R5,7 and O5,6,7.

Human bone is a three-dimensional composite structure consisting of inorganic apatite crystals and organic collagen fibers. An attractive strategy for fabricating mimics of these types of composite biomaterials is to selectively grow apatite on polymers with control of structure, mechanical properties, and function. In the present study, silk/apatite composites were prepared by growing apatite on functionalized nanodiameter silk fibroin fibers prepared by electrospinning. The functionalized fibers were spun from an aqueous solution of silk/polyethylene oxide (PEO) (78/22 wt/wt) containing poly(L-aspartate) (poly-Asp), which was introduced as an analogue of noncollageous proteins normally found in bone. Silk fibroin associated with the acidic poly-Asp and acted as template for mineralization. Apatite mineral growth occurred preferentially along the longitudinal direction of the fibers, a feature that was not present in the absence of the combination of components at appropriate concentrations. Energy dispersive spectroscopy and x-ray diffraction confirmed that the mineral deposits were apatite. The results suggest that this approach can be used to form structures with potential utility for bone-related biomaterials based on the ability to control the interface wherein nucleation and crystal growth occur on the silk fibroin. With this level of inorganic–organic control, coupled with the unique mechanical properties, slow rates of biodegradation, and polymorphic features of this type of proteins, new opportunities emerge for utility of biomaterials.

Compressive properties at 573–773 K of porous aluminum produced by the spacer method were investigated and compared with those of bulk reference aluminum with the same chemical compositions. The stress exponent and activation energy for deformation at elevated temperatures in the porous aluminum were in agreement with those in the bulk reference aluminum. In addition, the plateau stress of the porous aluminum was comparable to the stress of the bulk reference aluminum upon compensation by the relative density. Therefore, it is conclusively demonstrated that the mechanism of deformation at elevated temperatures in the porous aluminum is the same as that in the bulk reference aluminum. This is likely due to the homogeneous microstructure in the porous aluminum produced by the spacer method.

The resistivities of as-deposited Cu(4.2Ir), Cu(2.0W), and Cu(2.2W) films are 32.2, 25.4, and 28.0 μΩcm, respectively. These resistivities are significantly higher thanthat for pure Cu films. After annealing the Cu(4.2Ir) film at constant heating rate to 800 °C and the two Cu(W) films to 950 °C, the resistivities reduce to 28.4, 4.3, and 5.2 μΩcm, respectively. The smaller reduction in resistivity for Cu(4.2Ir) compared with that for Cu(W) is partly a consequence of solute redissolution following precipitation. The variation of resistivity with temperature for the films and the Cu-rich end of the binary phase diagrams are used to categorize the decomposition behavior of the Cu(Ir) and Cu(W). These categories were defined by K. Barmak et al., J. Appl. Phys.87, 2204 (2000). W is placed in category III along with V, Nb, Ta, Cr, Mo, Re, Ru, Os, B, and C. Ir most suitably belongs to Category II together with Fe and Co.

Well-aligned Ga2O3 nanowires were formed on the sapphire (0001) substrates at temperatures of 650–450 °C using a single precursor of gallium acetylacetonate via a vapor-liquid-solid (VLS) method. Structural analyses reveal that the well-aligned Ga2O3 nanowires are expitaxially grown on the sapphire (0001) with Ga2O3/ sapphire orientational relationship [201]||[0001] and [211]||[1120]. In addition, formation of the flowerlike Ga2O3 nanorod bundles at a temperature of 750 °C via the vapor-solid (VS) mechanism was also demonstrated. Instead of being catalysts in the VLS method, the Au nanoparticles are proposed to play a role in sinking the Ga vapor for forming the nuclei of Ga2O3 nanorods in the VS method.

To estimate the ratio of densification to Vickers indentation volume, three-dimensional images of Vickers indentations on several glasses, including silicate glasses and bulk metallic glass (BMG), were obtained before and after annealing using an atomic force microscope. Large volume recovery of Vickers indentation by annealing was observed for all glasses but BMG. Following previous studies, this recovered volume almost corresponded to the densified volume under a Vickers indenter, and the compositional dependence of densification was discussed. The ratios of densification to the total indentation volume for silica and soda-lime glasses were 92% and 61%, respectively. It was concluded that densification was a general property for silicate glasses and that the ratios of densification to the total indentation volume for all the glasses correlated well with Poisson’s ratios of the glasses.

An important component of the slurries used in chemical mechanical planarization (CMP) is an appropriately chosen corrosion/dissolution inhibitor, which facilitates selective material removal from protrusions while protecting recessed regions of the surface. The present work demonstrates the utility of two environmentally benign anionic surfactants, sodium dodecyl sulfate (SDS) and ammonium dodecyl sulfate (ADS) as dissolution inhibitors. Using a standard slurry (1 wt% glycine with 5 wt% H2O2 at pH = 4.0) typically used for Cu CMP and combining measurements of open circuit potentials and contact angles with those of Cu removal rates, we show that both SDS and ADS suppress chemical dissolution and polish rates of Cu. The dissolution inhibition efficiencies of ADS and SDS measured in these experiments are found to be superior to those of benzotriazole (BTA), a traditional inhibiting agent used for copper CMP.

Preferential Pb electromigration (EM) in eutectic Sn–Pb molten solder was characterized by examining Pb segregation at the anode of the solder on a thin stripe of Cu metallization. The eutectic Sn–Pb molten solder stressed at current densities of 103−104 A/cm2 was found to form columnar Pb-rich phase (α) at the anode side and Pb deficiency at the cathode side. The columnar α-phase grew in the direction parallel to the electron flow, and its growth rate increased proportionally with the current density applied through the molten solder. By measuring the growth rate of the columnar α-phase, we calculated the Pb effective charge number of EM in the eutectic Sn–Pb molten solder to be 2.7, which is one order of magnitude lower than the reported value of 47 for self-electromigration in bulk Pb. The mechanism for the EM-induced Pb segregation in Sn–Pb solder was also explored.

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.

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.