Semiconducting Bi1−xPbxBaO3−δ (or BPB) glasses with x = 0 to 0.8 have been prepared by fast quenching from the melt. Interesting anomalies in the temperature-dependent polaronic conductivity and dielectric constant have been observed in all these glass compositions at temperatures, Tp, varying from 310 to 330 K (depending on Pb concentration). This nonlinear behavior is considered to be associated with the local ordering or the displacements of the BiO3 type pyramidal structural units present in the glass matrix (observed from the infrared spectra of these glasses). This type of ordering/displacement gives rise to a local instability in the glass network structure which is also supported by the observed heat capacity anomaly around the same temperatures Tp.

The role of ozone in the reactive coevaporation of the lead zirconate titanate thin film was investigated by depositing films at various growth rates with various ozone fluxes or molecular oxygen fluxes on unheated substrates and then crystallizing them using rapid thermal annealing. The oxidation state of lead in the as-deposited film was determined from the ratio of the ozone to the total metal fluxes. The amount of atomic oxygen supplied to the surface of the film was at least 103 times larger when the deposition was done using ozone rather than molecular oxygen. When the ozone flux was more than one-third of the total metal flux, well-oxidized films were obtained. To ensure obtaining well-oxidized film, the ozone flax should be more than twice as much.

The wavelength dispersions of the Faraday effect in typical diamagnetic glasses, i.e., silica, borate, silicate, tellurite, lead-bismuth-gallate, and As2S3, have been examined. The Verdet constant of the glasses decreases with increasing wavelength in the longer wavelength region of the absorption edge of the glasses, while it increases with increasing optical bandgap of the glasses. These phenomena have been successfully explained based on the Becquerel theory. A guiding principle in designing a diamagnetic glass with a high Verdet constant is proposed.

Well-ordered, pure-phase epitaxial films of FeO, Fe3O4, and γ–Fe2O3 were prepared on MgO(001) by oxygen-plasma-assisted MBE. The stoichiometries of these thin films were controlled by varying the growth rate and oxygen partial pressure. Selective growth of γ–Fe2O3 and α–Fe2O3 was achieved by controlling the growth conditions in conjunction with the choice of appropriate substrates. Growth of the iron oxide epitaxial films on MgO at ≥350 °C is accompanied by significant Mg outdiffusion. The FeO(001) film surface exhibits a (2 × 2) reconstruction, which is accompanied by a significant amount of Fe3+ in the surface region. Fe3O4 (001) has been found to reconstruct to a structure. γ–Fe23 (001) film surface is unreconstructed.

Coordination state of gold atoms implanted in silica glass to an energy of 1.5 MeV and a dose of 1 × 1017 ions/cm2 has been studied by x-ray absorption fine structure spectroscopy. It was found that most of the gold atoms form gold clusters in which the nearest neighboring Au–Au interatomic distance is shorter by 0.05 °A than that in bulk gold. The contraction of Au–Au interatomic distance of gold clusters in silica glass is less than that reported in the previous studies on gold clusters within the other substrates. Gold atoms are coordinated by about four gold atoms in average. In addition, it was found that Au–O bonds are formed at the gold clusters/silica glass interface. It was deduced that the formation of Au–O bond at the gold clusters/silica glass interface depresses the contraction of Au–Au interatomic distance.

The effect of cosputtering small amounts of Ni (3%, 9%) and SbOx (20%) on the final microstructure of MoS2 lubricant thin films has been studied using a combination of scanning and transmission electron microscopy imaging, and electron and x-ray diffraction techniques. The early-growth, near-interface microstructure of both MoS2 and 3% Ni–MoS2 cosputtered films is revealed to be a mixture of (002) basal and elongated, large-size (100) and (110) edge islands. Cosputtering with 9% Ni induces a dramatic change in the microstructure, i.e., primarily basal domains with very small isolated regions of edge islands, while cosputtering with 20% SbOx produces films having no long-range order. The results are compared with and are consistent with previously published x-ray absorption fine structure data. The impact of film morphology on tribological performance is discussed.

The densification behavior of cordierite glass-ceramic films constrained on a rigid silicon substrate was studied in the temperature range from 900 °C to 1000 °C. An optical setup was used to obtain the thickness versus time profiles and in-plane stresses of the constrained glass-ceramic during isothermal sintering. The thickness profiles showed a rapid shrinkage due to sintering followed by an expansion corresponding to crystallization of the glass-ceramic. Measurements of in-plane stresses in constrained-sintering films showed a rapidly rising tensile stress during densification followed by a slight drop during crystallization. In films sintered above 950 °C, the tensile stress rose rapidly again near the end of crystallization, suggesting a further densification in a mostly crystallized film. Scanning electron microscope (SEM) micrographs of the film cross sections revealed the formation and growth of large pores along the interface between the glass-ceramic and silicon substrate that may have contributed to the observed film expansion. These pores are substantially larger than the initial pore size in the films, indicating that they were formed during sintering. We believe that poor wetting of the glass-ceramic on silicon may have contributed to the formation of the porous structure at the interface.

We describe the variation of structural and physical properties of mesocarbon microbeads, a potential anode material for rechargeable lithium batteries, as a function of heat-treatment temperature in the range 400–1100 °C. Scanning electron microscopy (SEM) studies indicated changes in the morphology of the mesocarbons with heat treatment. X-ray studies show that average crystallite size varies considerably with heat treatment. The d002 spacing decreases with increasing heat-treatment temperatures. The electronic conductivity of the mesocarbon microbeads also increases substantially with increasing heat-treatment temperature. Based on thermogravimetric analysis (TGA) and other measurements, we find that organic fractions volatilizes out of these carbons in two distinct stages. The observed weight loss correlates with the structural changes observed. We suggest that these observations are consistent with two types of hydrogenated fractions present in the “green” mesocarbons.

Ion irradiation on polytetrafluoroethylene (PTFE) has been carried out to improve adhesions to metals and to adhesive cements. Argon ions were irradiated on the polymer, by varying the amount of Ar+ from 1 × 1014 ions/cm2 to 1 × 1017 ions/cm2 at 1 keV, and 4 ml/min of oxygen gas flowed near the polymer surface during the ion irradiation. The wetting angle of water on the PTFE surface was changed from 100° to 70–150°, depending on the ion beam condition. The changes of the wetting angle and effects of Ar+ irradiation in oxygen environment were explained by the changes in surface morphology due to the ion beam irradiation onto PTFE, and formation of a hydrophilic group due to a reaction between the irradiated polymer chain and the blown oxygen. Strongly enhanced adhesion is explained by interlock mechanism, formation of electron acceptor groups on the modified PTFE, and interfacial chemical reactions between the irradiated surface and the deposited materials.

The crystallization kinetics and phase transformation of 10Li2O–14Fe2O3–11MnO2–25CaO–5P2O5–35SiO2 (LFMCPS) glass have been investigated using differential thermal analysis (DTA), Χ-ray diffraction (XRD), and scanning electron microscopy (SEM). The major crystalline phase determined by XRD analysis was triphylite [Li(Fe0.5Mn0.5)PO4], β–wollastonite (β CaO SiO2) and magnetite (Fe3O4) as the minor phases. The nonisothermal kinetics of crystallization of the LMFCPS glass was investigated using DTA analysis. The activation energy of crystallization for LFMCPS glass was 74.6 kcalymol. The growth morphology parameter n was 0.98 at a heating rate of 5 °C/min and decreased to 0.74 as the heating rate increased to 20 °C/min. The numerical factor of crystallization mechanism m was 0.57 at low crystallization temperature and gradually decreased as the temperature increased. For the experiment, the parameters n and m were approximately one. These results indicated that the surface nucleation was dominant in LFMCPS glass crystallization.

The structure of polyparaphenylene (PPP)-based carbons prepared by the Kovacic and Yamamoto methods heat-treated at 650–3000 °C have been characterized comparatively by using x-ray diffraction, SEM, TEM, and Raman spectroscopy. Both kinds of carbons indicate not typical but poor graphitizing behavior, especially for the case of PPP Yamamoto samples, and much less for PPP Kovacic samples, by heat treatment up to 3000 °C. The Kovacic-based samples heat-treated at 600–2400 °C have a more developed layer structure than that of Yamamoto-based samples. In contrast, for HTT's (heat-treatment temperature) more than about 2400 °C, PPP Yamamoto-based carbons exhibit a more developed crystallite structure than PPP Kovacic-based carbons. At a given HTT, PPP Kovacic-based carbons have a much more quinoid-like structure and graphene-type structure than PPP Yamamoto-based carbons, as indicated by the carbon yield and Raman scattering measurements. It is suggested that the detailed structure of the starting polymers influences the texture as well as the microstructure of resultant carbons even though both are obtained from the same kinds of precursors. These microstructures also largely influence the anode performance when these carbons are used in Li ion batteries.

Optical anisotropy of thin films of an organo-soluble flexible polyimide based on 1,4-bis(3,4-dicarboxyphenoxy) benzene dianhydride (HQDPA) and 2,2-dimethyl-4,4′-methylene dianiline (DMMDA) was detected by a prism-coupler technique. A mechanism is proposed, based on the model of gel film collapse. The degrees of optical anisotropy of the thin films were evaluated via the level of negative birefringence. The residual solvent in the films lessens the levels of negative birefringence so that the residual solvent must be evacuated. The levels of negative birefringence are independent on the solid content of the initial solution, but dependent on the thickness of the films. For a film of 16 μm thick, zero birefringence was achieved, postulated from the dependence of negative birefringence on the thickness of thin films. The relationship between the optical anisotropy and solution properties shows that the degrees of optical anisotropy of thin films on the same scale of thickness depend on macromolecular sizes in their dilute solutions.

Pure vapor-grown carbon nanofibers (VGCNF's) with controllable diameters of 10–200 nm were prepared by an improved floating catalyst method. Through transmission electron microscopy (TEM) observation, it was found that VGCNF's have a duplex structure, a hollow and high-crystallinity graphite filament called primary carbon fiber surrounded by a pyrocarbon layer with low graphite crystallinity. It was observed using high-resolution TEM that VGCNF's have excellent graphitic crystallinity with graphite layers stacked neatly parallel to fiber axis. Moreover, x-ray diffraction results showed that the graphitic crystallinity of carbon fibers became higher with decreasing diameter of carbon fibers.

The glass-crystalline transformation induced by laser irradiation is studied in MoO3. Before crystallization we have found that the system evolves from a low temperature glass phase to a high temperature glass phase. The crystallization kinetics depend strongly on the initial irradiation power. The power densities needed to induce the phase transformations, of the order of 15 W/mm2, are relatively low and suggest the possibility of using this material as a data storage medium.

The influence of microstructure on the indentation cracking behavior of molybdenum disilicide (MoSi2) has been examined. The indentation response of samples produced by various methods has been measured to examine the elastic/plastic nature, hardness, and fracture toughness. Fracture toughness comparisons were made by measuring indentation crack lengths, observing the elastic/plastic indentation response, and quantifying the differences in the indentation cracking behavior. Further information was gained by monitoring the acoustic activity during indentation for selected specimens. It has been observed that the fine grain size and the dispersion of the silica phase promote microcracking and crack deflection.

The phase formation sequence in Nb/Si multilayers formed at different deposition temperatures was investigated by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The amorphous phases were found to form in Nb/Si multilayers deposited at room temperature and 560 °C, but the compositions of these two amorphous phases were different. The crystalline Nb3Si and Nb5Si3 were formed in Nb/Si multilayers deposited at 180–500 °C. The interfacial energy and modified heat of formation are adopted to explain our obtained results. The occurrence of crystalline Nb5Si3, NbSi2, and amorphous silicide phase was found when the Nb/Si multilayers with Nb3Si phase were annealed at 550 °C, while only NbSi2 was found to form when annealing this sample at 700 °C. The mobility of Si takes an important role in phase formation in Nb/Si multilayers.

We use a topology optimization method to design 1–3 piezocomposites with optimal performance characteristics for hydrophone applications. The performance characteristics we focus on are the hydrostatic charge coefficient , the hydrophone figure of merit , and the electromechanical coupling factor . The piezocomposite consists of piezoelectric rods embedded in an optimal polymer matrix. We use the topology optimization method to design the optimal (porous) matrix microstructure. When we design for maximum and , the optimal transversally isotopic matrix material has negative Poisson's ratio in certain directions. When we design for maximum , the optimal matrix microstructure is layered and simple to build.

The solid state photochemistry of uranyl carboxylate complexes is presented with the purpose of developing methods for optical lithography of uranium oxide films. These complexes of the general formula, UO2(OOCR)2 (R = i-C3H7, C5H11, CH2C6H5, CH2OC2H5, C2H4OC2H5), were all photosensitive as thin amorphous films. The primary photochemical reaction for each of these complexes was the extrusion of a CO2 from the ligand and the production of radicals which initiated a chain reaction. The nature of this chain reaction was dependent upon the identity of the organic substituents, R. In some cases the chain reaction required a photochemical step while others were entirely thermal in nature. Of importance are the potentially high quantum yields which can be associated with thermal chain reactions. Some of the systems presented here exhibit quantum yields in excess of 1. This process was shown to be compatible with optical lithography by the patterning of the uranium oxide product on silicon surfaces.

Finite element simulation of conical indentation of a wide variety of elastic-plastic materials has been used to investigate the influences of pileup on the accuracy with which hardness and elastic modulus can be measured by load and depth-sensing indentation techniques. The key parameter in the investigation is the contact area, which can be determined from the finite element results either by applying standard analysis procedures to the simulated indentation load-displacement data, as would be done in an experiment, or more directly, by examination of the contact profiles in the finite element mesh. Depending on the pileup behavior of the material, these two areas may be very different. When pileup is large, the areas deduced from analyses of the load-displacement curves underestimate the true contact areas by as much as 60%. This, in turn, leads to overestimations of the hardness and elastic modulus. The conditions under which the errors are significant are identified, and it is shown how parameters measured from the indentation load-displacement data can be used to identify when pileup is an important factor.

The effects of indenter tip rounding on the shape of indentation loading curves have been analyzed using dimensional and finite element analysis for conical indentation in elastic-perfectly plastic solids. A method for obtaining mechanical properties from indentation loading curves is then proposed. The validity of this method is examined using finite element analysis. Finally, the method is used to determine the yield strength of several materials for which the indentation loading curves are available in the literature.