Surface damage from machining operations is a potential source of failure in metallic components. The ability to quantitatively characterize the depth and extent of the damage layer is critical to controlling the machining process. Electron back scattered diffraction and synchrotron high energy x-ray diffraction were applied to the measurement of machining surface damage in a Ni-based super alloy. Both techniques clearly showed a plastic deformation profile below the surface as a function of the machining conditions used. Using the average intragrain misorientation parameter, the electron back scattered diffraction was able to quantify the amount of surface damage from one surface treatment to another. In addition, the x-ray diffraction measurements were able to simultaneously measure the elastic strain as a function of depth from the surface.

A platinum (Pt) on pure ceria (CeO2) supported by carbon black (CB) anode was synthesized using a combined process of precipitation and coimpregnation methods. The electrochemical activity of methanol oxidation reaction on synthesized Pt-CeO2/CB anodes was investigated by cyclic voltammetry and chronoamperometry experimentation. To improve the anode property on Pt-CeO2/CB, the influence of particle morphology and particle size on anode properties was examined. The morphology and particle size of the pure CeO2 particles could be controlled by changing the preparation conditions. The anode properties (i.e., peak current density and onset potential for methanol oxidation) were improved by using nanosize CeO2 particles. This indicates that a larger surface area and higher activity on the surface of CeO2 improve the anode properties. The influence of particle morphology of CeO2 on anode properties was not very large. The onset potential for methanol oxidation reaction on Pt-CeO2/CB, which consisted of CeO2 with a high surface area, was shifted to a lower potential compared with that on the anodes, which consisted of CeO2 with a low surface area. The onset potential on Pt-CeO2/CB at 60 °C became similar to that on the commercially available Pt-Ru/carbon anode. We suggest that the rate-determining steps of the methanol oxidation reaction on Pt-CeO2/CB and commercially available Pt-Ru/carbon anodes are different, which accounts for the difference in performance. In the reaction mechanism on Pt-CeO2/CB, we conclude that the released oxygen species from the surface of CeO2 particles contribute to oxidation of adsorbed CO species on the Pt surface. This suggests that the anode performance of the Pt-CeO2/CB anode would lead to improvements in the operation of direct methanol fuel cells at 80 °C by the enhancement of diffusion of oxygen species created from the surface of nanosized CeO2 particles. Therefore, we conclude that fabrication of nanosized CeO2 with a high surface area is a key factor for development of a high-quality Pt-CeO2/CB anode in direct methanol fuel cells.

Nano-sized cerium-doped lutetium aluminum garnet (LuAG:Ce) powders were prepared via a sol-gel combustion process from a mixed solution of metal nitrates, using organic glycine as a fuel. The purified crystalline phase of LuAG:Ce was obtained after calcination at 1000 °C for 2 h. The obtained phosphors were agglomerated and had a foamy-like morphology, consisting of pointed crystallites with uniform size of about 40 nm. Both the photoluminescence and the radioluminescence of the calcined powders showed the same two emission bands, corresponding to transitions from the lowest 5d excited state (2D) to the 4f ground state of Ce3+ (2F5/2, 2F7/2). Using the prepared powders, polycrystalline LuAG:Ce optically transparent ceramics were successfully fabricated at 1850 °C for 10 h under vacuum without sintering aids and annealed at 1450 °C for 20 h in air. The sintered ceramics are transparent with an in-line light transmittance in the visible wavelength range of about 50% and have a uniform microstructure with an average grain size of about 8 μm. The radioluminescence of the transparent ceramics is similar to that for calcined powders, except higher in intensity.

Hydrophobic-hydrophilic patterns were formed on indium tin oxide substrates, and thick films of poly(phenylsilsesquioxane) (PhSiO3/2) particles, prepared by the sol-gel process, were selectively deposited onto hydrophilic areas of the substrates by electrophoresis. The films composed of PhSiO3/2 particles became transparent with morphological changes from aggregates of particles to a continuous phase after a heat treatment. After heat treatment at 200 °C, convex-shaped PhSiO3/2 micropatterns were formed on the hydrophilic region of the pattern. Moreover, the height of micropatterns was controlled by the deposition time. This patterning technique has a wide variety of applications such as fabrication of micro-optical components.

It is known that porous organosilicate glass (OSG) dielectrics tend to lose functional groups and become denser upon the chemical and physical action of the plasmas, but an accurate analysis and estimation of the depth and degree of film densification is not straightforward. In this study, we show that the combination of techniques like x-ray reflectivity, surface acoustic waves, and nanoindentation in depth-sensing and modulus mapping mode allow a complete and self-consistent physical analysis of the damage induced by the direct exposure of porous OSG films to different plasma ambients in reactive ion etching mode. We demonstrate for the chosen dielectric that the characteristics of the damage regions such as density and elastic modulus are very similar regardless of the reducing or oxidizing nature of the plasma. Nevertheless, the physical depth of the damage region shows large variation. Capabilities and limitations of each of the chosen analysis techniques are also discussed.

Single-crystal lead titanate [(001)PbTiO3 (PT)] thin films were heteroepitaxially grown on a miscut strontium titanate [(001)SrTiO3 (ST)] substrate by radio frequency magnetron sputtering. The PT thin films were grown via a step-flow growth. The step-flow growth enhanced the layer growth resulting in the continuous (001) single-crystal structure without a dislocated interface for the film thickness below 200 to 250 nm. The PT thin films show a small temperature variation of the lattice parameters unlikely to the bulk PT crystals due to the substrate clamping. The temperature variation of the lattice constants is discussed in terms of the thermo-elastic deformation analysis for the PT/ST heterostructure.

Low-energy ball milling technique was successfully used to synthesis new glassy Zr52Al6Ni8Cu14W20 multicomponent alloy powders using mechanical alloying method. During the intermediate stage of milling the atoms of Zr, Al, Ni, and Cu migrated and diffused into the W lattice to form a body-centered cubic solid solution phase. As the milling time increases, the obtained metastable powders are subsequently subjected to continuous defects and lattice imperfections that lead to a gradual change in the free energy so that solid solution phase transformed to another metastable phase (glassy). The glassy powders that were obtained after 720 ks milling are fully amorphous and have spherical-like morphology with an average particle size of 0.60 μm in diameter. The synthetic glassy Zr52Al6Ni8Cu14W20 alloy powder, which exhibits a glass transition temperature of 811 K, crystallizes at a high temperature (884 K) through a single sharp exothermic peak with an enthalpy change of crystallization of −5.48 kJ/mol. Whereas the supercooled liquid region before crystallization of the obtained glassy powders is 73 K, the reduced glass transition temperature (ratio between Tg and liquidus temperatures) was found to be 0.46. The fabricated glassy powders were consequently hot-pressed into bulk samples in an argon gas atmosphere at several temperatures with a pressure of 936 MPa. The samples that were consolidated within the temperature of the supercooled liquid region are fully dense, with relative density above ∼99.82%, and maintain their original homogeneous glassy structure. They have high Vickers microhardness values in the range between 8.46 and 8.62 GPa. They also show very high fracture strength (2.13 GPa) with an extraordinary high Young's modulus of 138 GPa. Neither yielding stress, nor plastic strain could be detected for this glassy alloy, the elastic strain of which is 1.47%.

Nastic structures are synthetic constructs capable of controllable deformation and shape change similar to plant motility, designed to imitate the biological process of nastic movement found in plants. This paper considers the mechanics and bioenergetics of a prototype nastic structure system consisting of an array of cylindrical microhydraulic actuators embedded in a polymeric plate. Non-uniform expansion/contraction of the actuators in the array may yield an overall shape change resulting in structural morphing. Actuator expansion/contraction is achieved through pressure changes produced by active transport across a bilayer membrane. The active transport process relies on ion-channel proteins that pump sucrose and water molecules across a plasma membrane against the pressure gradient. The energy required by this process is supplied by the hydrolysis of adenosine triphosphate. After reviewing the biochemistry and bioenergetics of the active transport process, the paper presents an analysis of the microhydraulic actuator mechanics predicting the resulting displacement and output energy. Experimental demonstration of fluid transport through a protein transporter follows this discussion. The bilayer membrane is formed from 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine] (Sodium Salt), 1-Palmitoyl-2-Oleoyl-sn-Glycero- 3-Phosphoethanolamine lipids to support the AtSUT4 H+-sucrose cotransporter.

Absorption and emission properties of Tm3+ in (1-x) (Ge0.25Ga0.10S0.65)-xCsBr glass (x = 0.00–0.12) were investigated. Upon 10 mol% CsBr addition, the absorption cross sections of Tm3+ decreased accompanied by a large increase in the lifetime of the Tm3+:3H4 level to 1.23 ms since Tm3+ ions were surrounded by the Br ions of [GaS3/2Br]− units. As the concentration of Tm3+ increased, the 3H4 level lifetime decreased due to cross relaxation (Tm3+:3H4,3H6→Tm3+:3F4,3F4). Temperature dependence of the 3H4 level lifetime showed that cross relaxation in Tm3+ is a phonon-assisted energy transfer process. When Tm3+ were surrounded by Br ions, cross relaxation among Tm3+ was also suppressed due to a decrease in the transition probability among Tm3+ energy levels, a decrease in phonon energy of the host glasses, as well as an increase in the number of phonons participating in the cross relaxation process. The potential of Tm3+-doped Ge-Ga-S-CsBr glasses for S-band fiber amplifiers is also discussed.

A new technique for measuring the elastic-plastic properties of porous thin films by means of nanoindentation is proposed. The effects of porosity on indentation hardness and modulus are investigated through finite element analyses based on the Gurson model for plastic deformation of ductile porous materials. Intrinsic mechanical properties of the thin film are obtained by eliminating both substrate and densification effects. The technique is applied to the special case of a porous, low-permittivity dielectric thin film. The results are in good agreement with those obtained independently using the plane-strain bulge test.

Single-crystal MoO3 nanowires were produced using the electrospinning technique. High-resolution transmission electron microscopy revealed that the one-dimensional nanostructures are 10–50 nm in diameter, on the order of 1–2 μm in length, and have the orthorhombic MoO3 structure. The structure, crystallinity, and sensoric character of these electrostatically processed nanowires are discussed. It has been demonstrated that the nonwoven network of MoO3 nanowires exhibits an order of magnitude higher sensitivity compared with that of a sol-gel based sensor. This is promising for use of the nanowire sensors in nanomedicine.

High-density tungsten/metallic glass composites were fabricated by warm extrusion of two different powders. The first powder was a physical blend of −45 μm tungsten and Hf-based metallic glass powders and produced a relatively coarse distribution of tungsten particles within a continuous metallic glass matrix. The second powder was synthesized by mechanical milling the −45 μm tungsten and Hf-based metallic glass powders into composite particles composed of 20–500-nm layers of tungsten and metallic glass. The amorphous structure of the starting glass powders did not change during milling. Some macroscopic plasticity during compression testing was observed due to the formation of multiple shear bands at the interface between the coarse tungsten particles and the metallic glass matrix in the composite produced from blended powders. In contrast, shear localization without a decrease in strength occurred uniformly throughout the nano-grained tungsten and metallic glass phases in the sample obtained from extruded composite powders.

Films with Fe–25 at.% Ge composition are deposited by the process of laser ablation on single crystal NaCl and Cu substrates at room temperature. Both the vapor and liquid droplets generated in this process are quenched on the substrate. The microstructures of the embedded droplets show size as well as composition dependence. The hierarchy of phase evolution from amorphous to body-centered cubic (bcc) to DO3 has been observed as a function of size. Some of the medium-sized droplets also show direct formation of ordered DO19 phase from the starting liquid. The evolution of disordered bcc structure in some of the droplets indicates disorder trapping during liquid to solid transformation. The microstructural evolution is analyzed on the basis of heat transfer mechanisms and continuous growth model in the solidifying droplets.

We report studies on the correlation between the microstructure, the magneto-crystalline structure, and the magnetic properties of barium hexaferrite powders. The samples consisted of typical hexagonal plate-like particles with approximate sizes of 80, 180, and 500 nm, obtained by microemulsion, coprecipitation, and solid-state reaction techniques, respectively, and were characterized by x-ray powder diffraction and scanning and transmission electron microscopy. The hyperfine parameters of the hexaferrite powders with different particle size were investigated by Mössbauer spectroscopy. We also measured the magnetization-versus-magnetic field dependence of the submicron powders at high magnetic fields up to 30 T at 4.2 K. Finally, we comment on the surface effects observed because of particle size reduction from micron to nanoscale dimensions.

Highly (111) textured Pb(Zr0.3Ti0.7)O3 (PZT 30/70) films were deposited on (0001) GaN/sapphire substrates using liquid-source metalorganic chemical vapor deposition (MOCVD) technique at 520 °C and 80 nm/min. The crystallinity of as-deposited PZT films and the structure of PZT/GaN interface were evaluated by x-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), respectively. Mitigated by geometric epitaxy and strain energy minimization, the orientation relationships of PZT on epi-GaN, determined using x-ray pole figure and selected area diffraction pattern, were as follows: out-of-plane alignment of [111] PZT//[0001] GaN, and orthogonal in-plane alignments of [112] PZT//[1100] GaN (zone axes) and [110] PZT//[1120] GaN. The nanochemistry of the PZT (150nm)/GaN interface, studied using analytical TEM, indicated a chemically sharp interface with interdiffusion limited to a region below 5 nm. The properties of as-deposited PZT on GaN by MOCVD are briefly compared with PZT by sol-gel processing, radio-frequency sputtering, and pulsed laser deposition.

Low-temperature processing as low as 550–700 °C of Pt/SrBi2Ta2O9 (SBT)/Bi4Ti3O12 (BIT)/p-Si heterostructure has been performed by a sol-gel method. The effects of annealing temperature on current density, C-V characteristics, and memory windows of Pt/SBT/BIT/p-Si heterostructure were investigated. The SBT/BIT multilayer films were polycrystalline with no pyrochlore phase and no preferred orientation. The leakage current density was under 3 × 10−7 A/cm2 at 5 V with asymmetry hysteresis loops for Pt/SBT/BIT/p-Si heterostructure. Although all C-V curves showed clockwise ferroelectric hysteresis loops and the memory window reached a maximum of 0.78 V at a sweep voltage of 5 V, the memory window changed asymmetrically with the variation of annealing temperature and sweep voltage. The maximum memory window of Pt/SBT/BIT/p-Si heterostructure prepared at lower temperatures was narrower at lower sweep voltage. The asymmetric behavior of the C-V characteristics was discussed in terms of electron injection from Si and the ferroelectric polarization effect.

A new type of nanocrystalline samarium-doped-ceria/yttrium-stabilized-zirconia (SDC/YSZ) heterophase thin film electrolytes was synthesized on MgO and Si substrates by spin coating and thermal treatment of SDC-nanoparticle-incorporated polymeric precursors. In the heterophase films, SDC nanoparticles were uniformly dispersed in a nanocrystalline YSZ matrix. The heterophase structure was stable when fired in air at temperatures up to 850 °C. The nanocrystalline heterophase thin films exhibited electrical conductivities significantly higher than that of the phase-pure YSZ and SDC nanocrystalline thin films at reduced temperatures. The effects of SDC grain size and volume fraction on the electrical conductivity of the heterophase films were also studied.

Monolithic nanoporous copper was synthesized by dealloying Mn0.7Cu0.3 by two distinct methods: potentiostatically driven dealloying and free corrosion. Both the ligament size and morphology were found to be highly dependent on the dealloying methods and conditions. For example, ligaments from 16 nm–125 nm were obtained by dealloying either electrochemically or by free corrosion, respectively. Optimization of the starting Mn–Cu alloy microstructure allowed us to synthesize uniform porous structures; but we found cracking to be unavoidable. Despite the presence of unavoidable defects, the nanoporous material still exhibits higher than expected yield strength.

Sputter-deposited, Al/Pt multilayer thin films of various designs exhibited rapid, self-propagating, high-temperature reactions. With reactant layers maintained at ∼21 °C prior to ignition and films adhered to oxide-passivated silicon substrates, the propagation speeds varied from approximately 20 to 90 m/s depending on bilayer dimension and total film thickness. Contrary to current Al–Pt equilibrium phase diagrams, all multilayers reacted in air and in vacuum transformed into rhombohedral AlPt having a space group R-3(148). Rietveld refinement of AlPt powder (generated from thin film samples) yielded trigonal/hexagonal unit cell lattice parameters of a = 15.634(3) Å and c = 5.308(1) Å; the number of formula units = 39. Rhombohedral AlPt was stable to 550 °C with transformation to a cubic FeSi-type structure occurring above this temperature.

Technical issues surrounding the use of nanoindentation at elevated temperatures are discussed, including heat management, thermal equilibration, instrumental drift, and temperature-induced changes to the shape and properties of the indenter tip. After characterizing and managing these complexities, quantitative mechanical property measurements are performed on a specimen of standard fused silica at temperatures up to 405 °C. The extracted values of hardness and Young's modulus are validated against independent experimental data from conventional mechanical tests, and accuracy comparable to that obtained in standard room-temperature nanoindentation is demonstrated. In situ contact-mode images of the surface at temperature are also presented.