Amorphous carbon filaments were synthesized by catalytic pyrolysis of propene over Pd3P colloids. The channel close to the center of the filaments usually contained particles, which were analyzed by analytical electron microscopy to be palladium. The palladium particles could be found anywhere along the filament. The carbon filaments were of two types and of different diameters, about 8–15 nm and about 40–80 nm. The thinner type of filament shows a channel diameter of about 5 nm. The type of filament produced depends on the reaction conditions. Increased reaction time results in a large number of filaments, whereas an increased propene gas flow results in more of the thicker type of filaments.

Pores in porous 6H–SiC were found to propagate first nearly parallel with the basal plane and gradually change direction and align with the c axis. As a consequence, well-defined columnar pores were formed. It was shown that the rate of change of propagation directions was influenced by the etching parameters, such as hydrofluoric acid concentration and current density. Larger currents resulted in formation of larger pores. Pore sizes were found to increase with depth due to a decrease of the acid concentration. In addition, due to chemical etching effects, larger pore sizes were obtained close to the sample surface.

Ammonium hydrogen carbonate was used as the precipitant to synthesize yttrium aluminate garnet (YAG) precursors from a mixed solution of aluminum and yttrium nitrates via coprecipitation. The carbonate precursor, with an approximate composition of NH4AlY0.6(CO3)1.9(OH)2 · 0.8H2O, transformed to pure YAG at 900 °C without the formation of intermediate phases. Reactive YAG powder was produced by calcining the precursor at 1100 °C. The YAG powder densified to 99.8% of the theoretical density by vacuum sintering at 1500 °C for 2 h, and the sintered body showed transparency. Less agglomeration of the precursor and good dispersity of the resultant YAG powder were responsible for the excellent sinterability.

With regard to substrate deformation, this work analyzed the microcantilever beam-bending test and provided a closed formula of deflection versus load. The substrate deformation was formulated using two coupled springs; the spring compliances were related to the elastic compliances of the substrate, the support angle between the substrate and the microcantilever beam, and the beam thickness. Finite element analysis was conducted to calculate the spring compliances and verify the analytic formula. The results showed that the proportionality factor of the load to the deflection was a third-order polynomial of the length from the loading point to the fixed beam end. Examples are also given to indicate the relative error of Young's modulus when evaluated with the beam-bending theory without considering the substrate deformation.

We present a laser-based direct write technique termed matrix-assisted pulsed-laser evaporation direct write (MAPLE DW). This technique utilizes a laser transparent fused silica disc coated on one side with a composite matrix consisting of the material to be deposited mixed with a laser absorbing polymer. Absorption of laser radiation results in the decomposition of the polymer, which aids in transferring the solute to an acceptor substrate placed parallel to the matrix surface. Using MAPLE DW, complex patterns consisting of metal powders, ceramic powders, and polymer composites were transferred onto the surfaces of various types of substrates with <10 micron resolution at room temperature and at atmospheric pressure without the use of masks.

The effect of strain rate on tensile ductility of moisture-induced embrittlement of Co3Ti alloys was investigated at ambient temperatures (298–353 K) by tensile test and scanning electron microscope fractography. The anomalous increase of tensile elongation and ultimate tensile stress was observed in a very low strain rate region and also at high temperatures, accompanied by an increase of area fraction in ductile transgranular fracture pattern. The anomalous strain rate dependence of tensile ductility was shown to become more evident with decreasing grain size and also with deviation from alloy stoichiometry. Oxidation on the alloy surface was suggested as a process counteractive to the hydrogen decomposition process from moisture in air.

The yield strength of Cu–Nb filamentary microcomposites was predicted as a function of Nb content by modifying the barrier strengthening model. To predict the variation of the yield strength with Nb content, the interfilamentary spacing was calculated as a function of Nb content on the basis of the assumption that Nb filaments are distributed regularly along the sides of triangular unit cells. The yield stress can be described as the sum of the substructural strengthening component and the filament boundary strengthening term. The good agreement between the prediction and the experimental data suggests that the strength increase in Cu–Nb filamentary microcomposites with increasing Nb content results mostly from increasing the volume fraction of Nb filaments, which act as barriers to plastic flow.

Quasicrystals (QCs) are known to exhibit unique properties as a result of their unique quasiperiodic structure. Real quasicrystalline (QC) materials, however, may exhibit complex phase structures, and as a consequence, their properties may differ from expectations. In the present work, QC coatings of the Al–Cu–Fe, Al–Cu–Fe–Cr, and Al–Pd–Mn systems were prepared by a plasma spray process, followed by heat treatments in the range 500–800 °C. The phase structure and evolution of the coatings were evaluated, and thermal diffusivity, hardness, and friction coefficient were measured. The presence of quasicrystalline and crystalline phases and their influence on these properties is systematically considered for the first time. Broadly, the coatings exhibit the properties expected of QC materials, low thermal diffusivity, high hardness, and low coefficients of friction, but it is also shown that these properties can be sensitive to the phase structure of the coatings. This suggests that phase structure may be manipulated by heat treatment to optimize the properties of QC coatings.

The phase diagram of the Sm2O3–CuO system was investigated by the combination of the differential thermal analysis and the quench method. The results showed that Sm2CuO4 incongruently melts at about 1220 °C, and that the solid Sm2CuO4 exists in equilibrium with the liquid consisting of 81–95 mol% CuO in the range of 1060–1220 °C. On the basis of the phase diagram, Sm2−xCexCuO4 single crystals were grown by the traveling solvent floating zone method. The crystal structure [space group I4/mmm, a = 3.917(1), c 4 11.899(2) Å] has been refined using single-crystal x-ray diffraction data with a precision corresponding to an R index of 0.02.

Tin oxide films were deposited on amorphous SiO2/Si and Si (100) substrates by ion-assisted deposition (IAD) at various ion beam potentials (VI) at room temperature and a working pressure of 8 × 10−5 torr. The structural and chemical properties of the as-grown tin oxide films were investigated to determine the effects of the oxygen ion/atom arrival ratio (Ri). X-ray diffraction patterns indicated that the as-grown films with different average energy per atom (Eave) showed different growth directions. The as-grown films with oxygen/Sn ratio (NO/NSn) of 2.03 and 2.02 had preferred orientation of (101) and (002), respectively. In addition, the as-grown film with low Ri was amorphous. Comparison of the observed d spacings with those for standard SnO2 samples, indicated that the crystalline as-grown films had compressive and tensile stress depending on Eave. In transmission electron microscopy analysis, a buffer layer of amorphous tin oxide was observed at the interface between the substrate and the film, and the crystalline grains were grown on this buffer layer. The crystalline grains were arranged in large spherical clusters, and this shape directly affected surface roughness. Rutherford backscattering spectroscopy spectra showed that the tin oxide thin films were inhomogeneous. The density of films decreased and the porosity and oxygen trapped in the films increased with increasing Ri. The densest film had about 6% porosity.

The combustion of zirconium in oxygen was simulated using a two-dimensional finite difference model. The model accounts for heat generation by the oxidation reaction and heat loss due to convective and radiative processes. Using geometric considerations along with the heat transfer conditions, the model was utilized to determine the effect of dilution and particle size on the combustion process. Dilution was examined in regular and random geometries and the results showed a marked influence on the nonlinearity of the wave. The effect of particle size was also examined as a function of the geometry of diluent dispersion.

A huge magnetic hardening (i.e., increase of coercivity from 5 A/m up to 4.4 kA/m) was reported for Fe75Si11B10Nb3Sn alloy ribbons during their very first stage of crystallization from an initial amorphous state. In contrast, Fe78Si11B10Sn1 showed no such hardening, while a moderate hardening was observed for Fe76Si11B10Nb3. This outstanding change was ascribed to the generation of metastable nanocrystallites that disappear upon heating at higher temperatures. A noticeable softening was then recovered (with a decrease of coercivity down to 0.8 kA/m) once the optimum homogeneous conventional nanocrystalline phase was achieved. Both structure and magnetic evolutions are followed by different techniques.

A fully dense in situ Al3Ti–Al2O3 intermetallic matrix composite containing about 30 vol% Al2O3 particles was prepared by combining squeeze casting with combustion synthesis using the chemical reaction between TiO2 and Al. The microstructure of the in situ composite was examined using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. Compressive behavior of the composite was investigated in the temperature range of 25–600 °C and compared with that of the as-cast Al3Ti alloy. The in situ formed spherical α–Al2O3 particles with a size of 0.2–1 μm were uniformly distributed in the Al3Ti matrix. The grain size of the Al3Ti matrix containing a small amount of Al2Ti precipitate was 2–10 μm. The compressive strength of the in situ composite was about 6–9 times that of the as-cast monolithic Al3Ti alloy and could be maintained at temperatures up to 600 °C. This was mainly attributed to the fine grain size of Al3Ti matrix and the rule of mixture strengthening of Al2O3 particles. The existence of Al2Ti phase and high dislocation density in the matrix also contributed positively to the composite strength.

Thermal and ion-transport properties of the salt-in-polymer system poly(ethylene oxide)n–LiN(CF3SO2)2 [P(EO)nLiTFSI] were investigated for compositions ranging from n = 5 to n = 50. Particular attention was paid to the region n = 8 to 10 where a crystallinity gap previously had been reported. We concluded that the absence of distinct melting transitions for salt-rich compositions (n = 5 to 12) was attributable to the extremely slow kinetics of recrystallization of this system following a heat treatment. The results further indicated that it was primarily the nucleation process that was inhibited by the [(bis)trifluoromethanesulfonate imide] (TFSI) anion. As a corollary, the ionic conductivity was strongly dependent on the thermal history of samples, and an enhancement of up to 300% was observed in the ambient temperature ionic conductivity for pre-heated salt-rich samples.

The thermal stability of RuO2/Si(100) films in air was studied using ex situ synchrotron x-ray scattering. The (110) textured RuO2 film showed good thermal stability due to the low surface and strain energies. However, the RuO2 films of high strain and surface energies were transformed to three-dimensional islands during annealing up to 800 °C. We also studied, during the post annealing process, the interface roughness of BaxSr1−xTiO3 (BST)/RuO2/Si(100) and BST/Pt/Ti/SiO2/Si(100) structures comparatively, using in situ synchrotron x-ray scattering. The interfaces of the BST/RuO2/Si were thermally stable up to 500 °C, and the deterioration of the interfaces above 500 °C was attributed to the crystallization of amorphous BST film. Meanwhile, the interfaces of the BST/Pt/Ti/SiO2/Si were significantly degraded even at the low temperature of 350 °C, mainly due to the formation of the Pt–Ti alloy and the Ti oxidation.

Polycrystalline Pb(ZrxTi1−x)O3 thin films with x = 0.6 and 1.0 were deposited at low temperatures (450–525 °C) on (111)Pt/Ti/SiO2/Si substrates by metalorganic chemical vapor deposition. The films were characterized by x-ray diffraction, electron microscopy, and electrical measurements. The texture of the films could be improved by using one of two template layers: PbTiO3 or TiO2. Electrical properties, including dielectric constants, loss tangents, polarization, coercive field, and breakdown field, were also examined. PbZrO3 films on Pt/Ti/SiO2/Si with a pseudocubic (110) orientation exhibited an electric-field-induced transformation from the antiferroelectric phase to the ferroelectric phase. The effect of varying processing conditions on the microstructure and electrical properties of the films is discussed.

The local structure of iron and uranium ions in a series of iron phosphate glasses with the general composition (40 – x)Fe2O3–xUO2–60P2O5 and (1–x–y)(40Fe2O3–60P2O5)– xUO2–y(Na2O or CaO) was investigated using Fe K-edge and U LIII-edge x-ray absorption fine structure spectroscopy. Replacing Fe2O3 by UO2 in the glass caused more distortion in the coordination environment of Fe(III) ions. Extended x-ray absorption fine structure fits revealed that the Fe–P bonds observed in the base glass also existed in all the waste-loaded glasses. X-ray absorption near-edge structure showed that the uranium ions were predominantly present as U(IV) in the glasses. Uranium ions were coordinated to approximately 8 ± 1 oxygen atoms and 2.5 ± 0.6 phosphorus atoms at an average distance of 2.47 ± 0.02 and 3.8 ± 0.02 Å, respectively. There were no Fe–U or U–Fe neighbors observed, indicating that uranium ions occupied voids in the glass away from the PO4 units. These conclusions were supported by Mössbauer, x-ray photoelectron, and Raman spectroscopic data.

The effective planar elastic moduli and planar conductivity (or dielectric constant) of regular hexagonal and triangular honeycombs were investigated for the entire range of volume fractions. Only the extreme limits of the volume fraction have been studied in the past. We studied the effective properties both numerically, via finite elements, and analytically, via rigorous three-point bounds, three-point approximations, and cross-property bounds. We show here that the three-point bounds and approximations are generally in excellent agreement with the simulation data and are superior to the two-point Hashin–Shtrikman bounds. Therefore, the three-point estimates provide accurate analytical predictions of the effective properties for all densities. Both the effective bulk modulus and effective conductivity are nearly extremal in the case of hexagonal honeycombs for the entire volume-fraction range, in contrast to the effective shear modulus. In the case of triangular honeycombs, all of the property values are relatively close to being optimal. Thus, the triangular honeycomb has desirable multifunctional performance for all densities in so far as the elastic moduli, conductivity, and dielectric constant are concerned.

The oxygen chemisorption on nanocrystalline SnO2 at temperature range between 100 and 450 °C was studied with differential thermal analysis (DTA) and electrical conductivity measurement. The O2−, O−, and O2m ionosorptions were observed and could be distinguished from each other only on nanocrystalline SnO2 with grain size less than 5 nm. Assuming steady-state adsorption, the heats of adsorption for O2− and O− (or O2−) on nanocrystalline SnO2 are 1.09 and 1.50 eV respectively from the results of DTA.

The small-angle x-ray scattering (SAXS) technique was used to investigate inhomogeneities on the scale of 10 to 600 Å in acid-catalyzed titania–silica and zirconia–silica xerogels. SAXS of (TiO2)x(SiO2)1−x and (ZrO2)x(SiO2)1−x xerogels with x < 0.1, in which there was no phase separation, showed the presence of two types of inhomogeneity. For Q < 0.05 Å−1 there was a clear departure from Porod scattering which showed that xerogel powder particle surfaces were rough. For 0.1 < Q < 0.4 Å−1 there was a plateau feature corresponding to micropores within the silica-based network, and this feature changes with heat treatment. SAXS of xerogels with x > 0.3 showed the presence of phase-separated regions of metal oxide, which were initially amorphous and crystallized at higher temperatures. A (TiO2)0.18(SiO2)0.82 xerogel that was not initially phase separated became phase separated after heat treatment at 750 °C due to reduced solubility of Ti in the silica network.