The crystallization behavior of amorphous TiOxNy (x ≫ y) thin films was investigated by in situ transmission electron microscopy. The Johnson–Mehl–Avrami–Kozolog (JMAK) theory was used to determine the Avrami exponent, activation energy, and the phase velocity pre-exponent. Addition of nitrogen inhibited diffusion, increasing the nucleation temperature, while decreasing the growth activation energy. Kinetic variables extracted from individual crystallites were compared to JMAK analysis of the fraction transformed, and a change of 6% in the activation energy led to agreement between the methods. From diffraction patterns and index of refraction the crystallized phase was found to be predominantly anatase.

The main objective of this work is to examine the feasibility of depositing aluminum nitride (AlN) powders, synthesized using self-propagating high-temperature synthesis, on a mild steel substrate using the detonation spray coating technique. Thick coatings produced by utilizing the AlN powder were obtained at four different oxygen–acetylene ratios and analyzed for microstructure, microhardness, porosity, indentation fracture toughness, and phase distribution. The AlN powder particles were found to be undergoing oxidation during the deposition process. The interrelationship between the spray parameters and the extent of oxidation of AlN during the coating process was investigated. Tribological performance of the coatings was evaluated using a dry sand abrasion test and a pin-on-disc sliding wear test. The mechanical and tribological properties of the above four coatings were compared with pure alumina (Al2O3) coatings. The correlation between the structure of the coatings and their tribological performance was also established.

B6O crystal growth from the B–B2O3 system was investigated at 1700–2200 °C and 4.5–6.5 GPa by using two different sample assemblies. Single B6O crystals over 100 μm in size have been synthesized at 5.5 GPa and 2100 °C. This makes it possible to study the properties of this interesting material. The factors affecting the B6O crystal morphology, size, color, and growth process were discussed. The solubility of B6O in B2O3 flux was estimated at 5.5 GPa and different temperatures. On the basis of the experimental results, we suggest two methods to grow large B6O crystals.

The formation of turbostratic boron nitride (tBN) phase on the cubic boron nitride (cBN) phase was investigated at specific conditions. The cBN film was deposited on the Si substrate by unbalanced magnetron sputtering. When the bias voltage at the substrate was adjusted to –85 V, the tBN phase nucleated on the cBN phase and grew simultaneously with the cBN phase. This was a critical bias voltage below which only the tBN phase was formed. The surface morphology of this film was typically shown as nodules dispersed on a very flat surface. The formation of nodulelike tBN phases seemed to be caused by a small variation of local stress on the growth surface. Once the nucleation of the nodulelike tBN phase occurred, the growth of tBN phase was accelerated. Transmission electron microscopy result showed evidence of the stress relaxation of the film caused by the formation of tBN phase at the interface of the tBN and cBN phases.

In this paper, series crystals Nd:Gd0.8La0.2VO4, Nd:Gd0.6La0.4VO4, and Nd:Gd0.45La0.55VO4 were grown by the Czochralski method. The structure and lattice constants of the series crystals were measured. The morphology of Nd:Gd0.8La0.2VO4 is discussed, and it is composed of {100} and {101} simple forms. The thermal expansion and specific heat of the Nd:Gd0.8La0.2VO4 crystal were also measured. The absorption and emission spectra of the Nd:Gd0.8La0.2VO4 and Nd:Gd0.6La0.4VO4 crystals were measured at room temperature. The laser outputs at 1.06 and 1.34 μm were determined when a crystal sample of Nd:Gd0.8La0.2VO4 was pumped by a laser diode at 808 nm, and the visible green and red laser outputs of the intracavity frequency double at 0.53 and 0.67 μm were determined when nonlinear KTiOPO4 and LiB3O5 crystals were used.

In continuation of our previous work [J. Ovenstone, P.J. Titler, R. Withnall and J. Silver, J. Phys. Chem. B, 105, 7170 (2001)] we report the following results. Amorphous europium-doped titania phosphors (Ti1−3xEu4xO2) were prepared with europium concentrations from x = 0.000397 to x = 0.143. From investigations using photoluminescence (PL), it was deduced that the luminescence was due to a europium/titanium compound rather than from a europium-containing precipitate dispersed within a titania precipitate. PL brightness was shown to increase linearly to a concentration of x = 0.0159 before quenching began, and the rate of increase of brightness dropped. Brightness then continued to rise (almost linearly) from x = 0.0238 to x = 0.143. Under electron beam excitation these phosphors showed weak cathodoluminescence; for the amorphous materials no quenching was observed. For the crystalline materials (prepared by annealing the amorphous materials at high temperature) no red luminescence was observed above a concentration of x = 0.00318; however, some faint red luminescence was observed below this concentration. In addition, some faint blue emission was observed in crystalline samples that had no red luminescence, indicating the presence of small amounts of Eu2+ ions. This was attributed to reduction of the Eu3+ ions in the electron beam. Europium doping was shown to increase the size of the band gap in the amorphous materials, but had little effect on the band gap of the crystalline powders.

Multilayered ceramic capacitors (MLCCs) with BaTiO3–BaZrO3 (BTZ) dielectric layers were fabricated, and the dielectric permittivity of the BTZ layers with different thicknesses in MLCCs was measured. The dielectric permittivity of the BTZ ceramic disk was also measured under various ac electric fields. The variation in the dielectric behaviors with the thickness of BTZ layers in MLCCs was explained by the ac-field dependence of dielectric permittivity observed in the BTZ ceramic disk. The ac-field dependence of dielectric permittivity of BTZ was markedly observed below the temperature of a broad maximum in the dielectric permittivity versus temperature (є versus T) curve. It was found that the temperature of the broad maximum shifted to the low-temperature side and the peak shape became asymmetric with increasing ac field. These changes in the dielectric properties under high ac fields were explained by a model of relaxors with the concept of the formation of polar microregions (PMRs) and the freezing of fluctuating ipoles in PMRs.

Intermetallic compound (IMC) growth during solid-state aging at 125, 150, and 170 °C up to 1500 h for four solder alloys (eutectic SnPb, Sn–3.5Ag, Sn–3.8Ag–0.7Cu, and Sn–0.7Cu) on Cu under bump metallization was investigated. The samples were reflowed before aging. During the reflow, the solders were in the molten state and the formation of the IMC Cu6Sn5 in the cases of eutectic SnPb and Sn–3.5Ag had a round scallop-type morphology, but in Sn–0.7Cu and Sn–3.8Ag–0.7Cu the scallops of Cu6Sn5 were faceted. In solid-state aging, all these scallops changed to a layered-type morphology. In addition to the layered Cu6Sn5, the IMC Cu3Sn also grew as a layer and was as thick as the Cu6Sn5. The activation energy of intermetallic growth in solid-state aging is 0.94 eV for eutectic SnPb and about 1.05 eV for the Pb-free solders. The rate of intermetallic growth in solid-state aging is about 4 orders of magnitude slower than that during reflow. Ternary phase diagrams of Sn–Pb–Cu and Sn–Ag–Cu are used to discuss the reactions. These diagrams predict the first phase of IMC formation in the wetting reaction and the other phases formed in solid-state aging. Yet, the morphological change and the large difference in growth rates between the wetting reaction and solid-state aging cannot be predicted.

This paper reports on a study of stress in thin silicon plates sectioned from wafers by a near-infrared transmission technique. Phase stepping was incorporated to determine the magnitude and orientation of stress from fractional birefringence fringe images. The anisotropic relative optic-stress coefficient of (100) silicon was determined and the limitation of the stress orientation measurement is discussed.

A bulk metallic glass-forming Ti–Cu–Ni–Sn alloy with in situ formed composite microstructure prepared by both centrifugal and injection casting presents more than 6% plastic strain under compressive stress at room temperature. The in situ formed composite contains dendritic hexagonal-close-packed-Ti solid solution precipitates and a few Ti3Sn, β –(Cu, Sn) grains dispersed in a glassy matrix. The composite microstructure can avoid the development of the highly localized shear bands typical for the room-temperature deformation of monolithic glasses. Instead, highly developed shear bands with evident protuberance are observed, resulting in significant yielding and homogeneous plastic deformation over the entire sample.

The possible role of microstructural features in determining the self-affinity of the fracture surface of a cast aluminum alloy is explored in this work. Fracture surfaces generated both in tension and impact tests were topometrically analyzed by atomic force microscopy, scanning electron microscopy, and stylus profilometry. The roughness exponent exhibited the “universal” value ζ ≈ 0.78, and the correlation length ζ was of the order of the grain size. The brittle intermetallic compounds known to be important in crack initiation did not show any correlation with the self-affine parameters of the resulting fracture surfaces in this particular case.

Cellular solids were processed from machined scraps of a medium carbon steel by sintering. Mechanical properties of the cellular solids were investigated by compressive tests from the viewpoint of effects of high dislocation density in the machined scraps on the solid-state bonding. The flow stress in the plateau region for the cellular solid made of the as-machined scraps was higher than that of the one made of the annealed scraps. Clearly, the bonding strength between scraps was increased by the high dislocation density in the as-machined scraps.

We investigated the crystal structure of Ti3SiC2 by means of high-resolution electron microscopy (HREM). Two polymorphs, α– and β–Ti3SiC2, were identified. The amount of the α phase was larger than the β phase, indicating that the former has lower energy than the latter. We also found that the bright spots in HREM images of Ti3SiC2 do not necessarily correspond to the atomic columns; thus an intuitive interpretation of the image contrast in terms of the stacking sequences of the close-packed layers should be made cautiously

Chemical vapor infiltration (CVI) has been widely studied under several conditions to obtain C/C composites. A “film boiling technique” (so-called Kalamazoo), by the use of liquid precursor, based on thermal gradient CVI has been recently developed as one of the very effective techniques to increase the carbon yield and the densification rate. A small cold wall type laboratory reactor has been realized to analyze the kinetics of reactions and the deposited pyrocarbon matrix. In this study, ferrocene, as the source of catalyst, is mixed to the liquid precursor to induce a catalytic effect on the film boiling technique since the transition metals are known to increase the carbon deposition rate. In addition to an important increase of the densification rate, it is revealed that the deposition mechanism and microtextures are completely modified by the presence of catalyst, with the presence of multiwall nanotubes within the matrix. A model has been adapted from Allendorff and Hunt's work to interpret this peculiar deposition mechanism.

We report up to 6 wt% storage of H2 at 2 atm and T = 77 K in processed bundles of single-walled carbon nanotubes. The hydrogen storage isotherms are completely reversible; D2 isotherms confirmed this anomalous low-pressure adsorption and also revealed the effects of quantum mechanical zero point motion. We propose that our postsynthesis treatment of the sample improves access for hydrogen to the central pores within individual nanotubes and may also create a roughened tube surface with an increased binding energy for hydrogen. Such an enhancement may be needed to understand the strong adsorption at low pressure. We obtained an experimental isosteric heat qst = 125 ± 5 meV. Calculations are also presented that indicate disorder in the tube wall enhances the binding energy of H2.

We have examined galena powders with the aim of providing information about the preparation mode of such powders from ancient Egyptian burial objects. Two extreme conditions of milling have been used to prepare galena powders in the laboratory, and the resulting products have been examined using scanning electron microscopy and transmission electron microscopy (TEM). The microstructure of hand-crushed coarse particles consists mainly of dislocation tangles. Annealing at 300 °C promotes a substantial recovery of the dislocation structure with the formation of subboundaries. Energetic ball milling produces a large variety of particle sizes, from 10 nm to several micrometers, with grains containing very high dislocation densities. Although PbS is a soft plastic compound, its fragmentation occurs down to very small sizes along various fracture regimes like in many brittle materials. Comparisons are made between TEM observations and the data obtained from x-ray diffraction peak profile analysis.

In this work, the solid solution series directionally solidified eutectic, Co1−xNixO/ZrO2(CaO), 0 ≤ x ≤ 1, was examined as a possible model system for interfacial fracture studies. These materials were grown by the optical floating zone method in an image furnace under controlled atmospheres to prevent the formation of Co3O4. For all compositions, lamellar microstructures were produced. The interface plane orientation relationship {111} Co1−xNixO║{100} ZrO2(CaO) was maintained throughout the solid solution series. The phase compositions were close to nominal values with some solubility of CoO in ZrO2(CaO). Preliminary indentation measurements demonstrate the onset of interfacial delamination for compositions of x <0.2.

By combining the cross-sectional observation of the randomly oriented film areas and the analyses of the film microstructural influence by the substrate-surface morphology, we achieved a novel understanding of the YBa2Cu3O7–x (YBCO) thin film growth process, which leads to an explanation of different microstructures formed in YBCO thin films. Selective and competitive growth of YBa2Cu3O7–x and Ba–Cu–O/Cu–O was found to occur in the whole film growth process depending on the local surface roughness in which the interfacial energy played a controlling role.

The synthesis of lithium tantalate films by a chemical solution deposition method was studied. A precursor solution was prepared by dissolving lithium ethoxide and tantalum pentaethoxide in ethanol. The addition of formic acid to this precursor solution was very effective in the preparation of homogeneous and transparent precursor films on substrates by spin coating. Lithium tantalate films crystallized on sapphire (001) substrates with a highly preferred orientation along the c axis with heat-treating at temperatures above 450 °C. The refractive index of the film prepared at 550 °C was 2.049, which is close to the value for single crystals of lithium tantalate (2.176).

This work presents the preliminary experimental results of Pb(ZrxTi1−x)O3 (PZT) thin films preparation to develop a new combinatorial process by chemical solution deposition (CSD) method. PZT thin films were fabricated from the PbZrO3 (PZ) and PbTiO3 (PT) multilayers on a substrate of Si/SiO2/Ti/Pt. The precursor PT and PZ solutions were coated in different sequences, (i) in the PT start sequence and (ii) in the PZ start sequence, and with different PT and PZ concentrations. It was found that the deposition sequence of PT and PZ led to the differences in composition, microstructure, texture, and ferroelectric property of the resultant thin films. The PT start deposition was suitable for preparation of the PZT thin films, while the PZ start deposition caused composition deviation and bad ferroelectric property. The postannealing had little effect for the formation of the PZT thin films from the multi-PT and PZ layers. A single perovskite phase of PZT can be obtained from the deposited multi-PT and PZ layers even without any postannealing when concentrations of the precursor PT and PZ solution are smaller than 0.025 M and the deposition sequence is in the PT start sequence. This method would be a constructive way to develop and study other thin film materials systems.