Sputtered TiN (30–120 nm thick)/Ti (30 nm thick) films were studied as a diffusion barrier between silicon substrate and copper films. The effects of TiN thickness and the existence of a SiO2 layer between Ti and silicon substrate on the diffusion barrier property were investigated using various characterization methods. The copper diffusion barrier property of TiN/Ti was found to be affected not only by the TiN thickness, that is diffusion distance, but also by the microstructure of the TiN, which changes with the thickness of TiN film. The existence of the SiO2 layer enhanced the diffusion barrier property of TiN/Ti. This is because the SiO2 layer between Ti and Si inhibited the formation of titanium silicides, so the Ti layer was available to be used as the sacrificial diffusion barrier for copper.

A polyvinylmethylsilane precursor has been used for the epitaxial growth of SiC thin films on 6H–SiC single crystal substrates. The films were prepared by dipping the single crystal 6H–SiC substrates into the precursor polymer solution with subsequent thermal treatments at different temperatures. Transmission electron microscopy (TEM) was used to characterize the microstructure and chemistry of the different SiC films. At 1100 °C, the film was amorphous and contained substantial oxygen. At 1600 °C, an epitaxial, single crystalline β–SiC film was observed.

Metallic RuO2(110) thin films were grown by oxygen-plasma-assisted molecular beam epitaxy (MBE) on MgO(100) and (110) at 425 °C. RuO2 films on MgO(100) are epitaxial with two variants, while RuO2 films on MgO(110) are highly oriented with the (110) face parallel to the substrate surface. The two variants in the RuO2(110) epitaxial films resulted in a twofold mosaic microstructure. The RuO2(110) epitaxial films are very smooth and exhibit a low resistivity of ∼ 36 μΩ-cm. In contrast, the RuO2(110) textured films are very rough, and consist of small grains with a poor in-plane alignment. A slight higher resistivity (49 μΩ-cm) was found for the RuO2 (110) textured films grown on MgO(110).

A hot-pressing aided exothermic synthesis (HPES) technique to fabricate NiAl matrix composites containing 0 and 20 vol.% TiB2 particles was developed. The conversion of mixtures of elements to the product was complete after processing, and TiB2 particles in the matrix were uniformly dispersed. The microstructure and interfaces were very thermally stable. The interfaces between NiAl and TiB2 were atomically flat, sharp, and generally free from interfacial phases. In some cases, however, thin amorphous layers existed at NiAl/TiB2 interfaces. At least three kinds of orientation relationships between TiB2 and NiAl were observed. The compressive yield strengths at room temperature and at 1000 °C of the composite were approximately three times as strong as those of the unreinforced NiAl. The tensile yield strength at 980 °C of the composite was about three times stronger than that of NiAl. The ambient fracture toughness of the composite was slightly greater than that of the monolithic NiAl.

We calculate the optimized geometry and the corresponding electronic structure of Li ions doped in a small graphite cluster with dangling bonds or hydrogen terminations at the edge surrounding the cluster. The calculations imply both covalent and ionic bonds of Li ions to carbon atoms, which may be relevant to explaining the broad signal of the 7Li NMR Knight shift spectra. Li intercalation, in particular, is possible even at the hydrogen-terminated edges. Because of the finite size effect of the cluster, the ionicity of intercalated Li ions has a large distribution of values, ranging from positive values close to that in graphite intercalation compounds to even slightly negative values, depending on the bonding geometry. We propose that the cluster edge surface plays a special role in accommodating excess Li ions in the disordered graphite system.

A model of lanthanum orthoniobate which possesses a ferroelastic tetragonalmonoclinic phase transition is proposed. It contains only one particle per unit cell, but it is constructed consistently with symmetry changes at the phase transition. The model parameters are chosen to reproduce the bare soft mode, degree of deformation of the tetragonal unit cell to a monoclinic one, and the phase transition temperature. The ferroelastic system with free boundary conditions was simulated by the molecular dynamics technique, and the second order phase transition was reproduced. The studied annealing process shows formation of the stripe lenticular domain pattern, which has been interrupted by the appearance of a temporary band of perpendicularly oriented lenticular domains. The maps contain W′-type domain walls whose orientations are fixed only by interplay of potential parameters and not by symmetry elements. The simulated domain pattern has the same features as those observed by transmission electron microscopy.

Geometrical effects on the cooling performance of the thin film thermoelectric (TFTE) modules were investigated by varying the film thickness and the number of p/n couples of the (Bi, Sb)2Te3/Bi2(Te, Se)3-based system which were fabricated by the flash evaporation technique. Maximum temperature difference (δTmax, maximum cooling) and optimum input current (Iopt) increased with film thickness for a fixed number of couples. For the case of given thickness, however, Iopt decreased with the number of couples, maintaining almost constant δTmax. The measured values for the cooling characteristics were compared with the results obtained through computer simulation work by the finite difference method (FDM). The thinner the film and the larger the number of p/n couples of the modules, the larger was the deviation between the experimental and the simulated values.

Polycrystalline LSCO/PNZT/LSCO ferroelectric capacitor heterostructures were grown by pulsed laser deposition using a composite conducting barrier layer of Pt/TiN on poly-Si/Si substrate. The growth of the ferroelectric heterostructure is accomplished at a temperature in the range of 500–600 °C. This integration results in a 3-dimensional stacked capacitor-transistor geometry which is important for high density nonvolatile memory (HDNVM) applications. Transmission electron microscopy shows smooth substrate-film and film-film interfaces without any perceptible interdiffusion. The ferroelectric properties and reliability of these integrated capacitors were studied extensively at room temperature and 100 °C for different growth temperatures. The capacitors exhibit excellent reliability, both at room temperature and at elevated temperatures, making them very desirable for HDNVM applications.

Changes in structure and phase transition behavior of (Na1/2Bi1/2)1−xSrxTiO3 were investigated using x-ray diffraction (XRD) analysis and dielectric measurements. A decrease in the degree of lattice distortion was observed when the structure was rhombohedral (x < 0.26). Further substitution of Sr2+ (x ≥ 0.26) caused (Na1/2Bi1/2)1−xSrxTiO3 to show no macroscopic lattice distortion. However, all investigated samples (0.1 ≤ x ≤ 0.5) were ferroelectric at room temperature regardless of the lack of lattice distortion found in XRD patterns. Further XRD investigations revealed that nonuniform strains caused by nonuniform polarized islands were responsible for this behavior. A-site cation substitution of Sr2+ also resulted in the decrease of Tmax (the temperature where dielectric constant is maximum). Typical relaxor ferroelectric phase transition behavior, associated with the shift of Tmax, with respect to the measuring frequencies, was found above x = 0.18. This could be also ascribed to the decrease of Tmax—this reveals the increase in the shift of Tmax with frequency, with associated decrease in ionic displacement and space charge contributions and associated increase in the relative contribution to the polarization by microdomains and domain walls at temperatures near Tmax.

TiB2, along with MgO and Mg3B2O6, was formed by a thermite reaction between Mg, amorphous B2O3, and TiO2 powders in argon. The mixture 5Mg–TiO2–B2O3 along with binary mixtures and single components were analyzed using differential thermal analysis (DTA) and x-ray diffraction (XRD). Large (25 g) specimens were also ignited in bulk using a resistance-heated nichrome wire. The reaction path in forming TiB2 in the three component mixture was deduced. Mg reduces TiO2 and B2O3 to form Ti and MgB2, respectively, which in turn react to form TiB2. In an oxidizing atmosphere, the significant speed of the reaction permitted solid state reaction to form TiB2 before atmospheric oxygen could diffuse into the powder mass and react to form oxide phases. Thermite reactions in air have the advantage (over furnace heating in air) of not providing time at elevated temperatures for Mg and intermediate products to become consumed in the formation of oxides, nor time for oxidation degradation of TiB2.

Dense and translucent ceramics were prepared by sintering of cylindrical preforms of hydroxyapatite extruded from xerogels. Extruded specimens were dried as monoliths and then consolidated by applying cold isostatic pressure, ranging from 500 to 1500 MPa. Upon heating the samples began to densify at 610 °C, and the densification/sintering was completed at 870 °C as was evidenced by the dilatometry plot indicating no further shrinkage. The sintered specimens thus formed were translucent in appearance. Further heating of the samples up to 1200 °C resulted in their “bloating” or creation of pores in the originally dense matrix. Pore creation within the structure is reproducible, it proceeds from the surface to the interior of the sample, and its spreading can be thermally controlled. Pore evolution within the single phase dense polycrystalline material is not related to the frequently occurring phenomenon of microcracking in ceramics during cooling.

An optimized chemical vapor infiltration (CVI) process has conditions that promote complete densification at the fastest allowable reaction rate. In order to help define optimum conditions, a model has been developed to simulate the CVI of a fibrous specimen for determining the effects of temperature gradients along with the other processing parameters such as pressure, size, chemistry, rate of reaction, and porosity on the resulting deposition profiles. This model simulates the deposition of alumina matrix within fibers wrapped around a tube. This symmetry reduces the model to a simple one-dimensional problem. Parameters for transport properties, calculated using a local microstructure model, are used in this macroscopic model. The model is applied as a guideline for choosing optimum conditions for producing a dense ceramic matrix composite. From this model, process diagrams are constructed that can help an experimentalist to choose the best conditions for the CVI process using temperature gradients.

Oxide-rich planar faults within a perovskite matrix are the prevailing type of extended defects in polycrystalline SrO-doped CaTiO3. These defects form, depending on the temperature of sintering, random networks, or ordered structures. The chemistry of the polytypoid, the isolated planar faults, and the perovskite phase have been studied by spatially resolved electron energy-loss and energy-dispersive x-ray spectroscopies using a dedicated scanning transmission electron microscope. We have found that Sr ions from SrO additions preferably substitute Ca in the CaTiO3 lattice, thus forming a solid solution (Ca1–xSrx)TiO3. The surplus of Ca ions forms single and ordered CaO-rich planar faults in the host (Ca1–xSrx)TiO3 phase. Whereas the excess Ca segregates in a form of single planar faults at lower temperatures, it forms a stable polytypoidic phase at higher temperatures. For materials having up to 25 mol% of SrO additions, this phase has (Ca1–xSrx)4Ti3O10 composition, comprising a sequence of CaO faults followed by three (Ca1–xSrx)TiO3 perovskite layers. Analytical electron microscopy revealed that the composition of the single planar faults, formed at lower temperatures, is identical to that of polytypoids, which are stable at higher sintering temperatures.

Highly (100)-oriented thin films of PbTiO3 were prepared on (100)-textured LNO/Pt/Ti/SiO2/Si substrates by rf magnetron sputtering at temperatures ≥480 °C, while randomly oriented PbTiO3 films were obtained on Pt/Ti/SiO2/Si substrates. The textured LNO layer can help to control the orientation of PbTiO3 thin films, and reduce their surface roughness quite significantly. The dielectric constant (εT) of PbTiO3 films deposited on LNO was lower than that of films on Pt and the dielectric loss (tan δ) increased when a higher deposition temperature or longer time was used. The highly (100)-textured PbTiO3 films also showed different ferroelectric hysteresis characteristics, i.e., a higher coercive field and a lower remanent polarization, from that of randomly oriented films deposited on Pt.

The dependence of the optical and mechanical properties of optically transparent polymethyl methacrylate (PMMA) composites on the annealing temperature of BK10 glass fibers was investigated. Annealing was used to modify the refractive index (R.I.) of the glass fiber so that it would more closely match that of PMMA. Annealing increased the refractive index of the fibers and narrowed the distribution of refractive index of the fibers, but lowered their mechanical strength so the mechanical properties of composites reinforced with annealed fibers were not as good as for composites containing as-pulled (chilled) glass fibers. The refractive index of as-pulled 17.1 μm diameter fibers (R.I. = 1.4907) increased to 1.4918 and 1.4948 after annealing at 350 °C to 500 °C for 1 h or 0.5 h, respectively. The refractive index of glass fibers annealed at 400 °C/1 h best matched that of PMMA at 589.3 nm and 25 °C, so the composite reinforced with those fibers had the highest optical transmission. Because annealed glass fibers had a more uniform refractive index than unannealed fibers, the composites made with annealed fibers had a higher optical transmission. The mechanical strength of annealed fiber/PMMA composites decreased as the fiber annealing temperature increased. A composite containing fibers annealed at 450 °C/1 h had a tensile strength 26% lower than that of a composite made with as-pulled fibers, but 73% higher than that for unreinforced PMMA. This decrease was avoided by treating annealed fibers with HF. Composites made with annealed and HF (10 vol. %)-treated (for 30 s) glass fibers had a tensile strength (∼200 MPa) equivalent to that of the composites made with as-pulled fibers. However, as the treatment time in HF increased, the tensile strength of the composites decreased because of a significant reduction in diameter of the glass fiber which reduced the volume percent fiber in the composite.

Carbon nitride films have been synthesized at low substrate temperature by Ar+ sputtering a graphite target with concurrent N+ assisted bombardment. It was disclosed that N+ bombardment with low energies of 150–400 eV and beam densities of 0.16–0.23 mA cm−2 was favorable to grow carbon nitride films with high N/C atomic composition ratios of 0.47–0.56. The spectra of x-ray photoelectron spectroscopy and infrared spectroscopy show that the low energy N+ bombardment activates nitrogen atoms to combine carbon atoms in unpolarized covalent bonds. Under the 150–300 eV and 0.16–0.23 mA cm−2 N+ assisted bombardment, the formed films are identified by transmission electron microscopy to possess the β–C3N4 microcrystalline structure. The films exhibit an extremely high hardness of 5260 kgf/mm2, a high resistivity of 4.8 × 1012 Ω × cm, and excellent optical transmittance. Friction and wear tests show that carbon nitride films on steel substrate can perform the even wear in low friction coefficients of 0.05–0.16 while raising wear loads up to 20 N.

The development of preferred orientation in AlN thin films deposited on silica glass substrates by rf sputtering at low substrate temperature (<150 °C) has been studied. The main factors controlling the preferential orientation of the AlN thin films are the ion-bombardment energies, incidence angle of the arriving particles, and deposition rate. At low pressure, a perpendicular and highly directional energetic ion-bombardment induces an orientation of the crystallites with their c-axis perpendicular to the substrate surface. At higher pressure (>15 mTorr), a spreading in the incidence angle of the arriving particles, due to gas phase collisions, favors the formation of AlN crystal twinning. A change in the preferred orientation of the films from (0001) to (1011) for deposition rates above 1.8 Å/s is observed.

Diamond-like carbon (DLC) films have been prepared by electrolysis of methanol solution using a pulse-modulated source. The deposition rate of the films is enhanced significantly compared to that of dc value. That the films do not contain bonded hydrogen is confirmed by infrared spectra. The structures of the films are characterized by Raman spectroscopy. These films show chemical inertness and hardness values in the range 12.5–19 GPa. Current-voltage characteristics of the films are measured, indicating that the resistivity is in the 107 Ω cm range and the breakdown field is larger than 1 MV cm−1.

The microstructure of Mo in an alumina/frit matrix was found to be dependent on the initial particle sizes of the alumina and Mo powders, the glass content in the matrix ceramic, and the amount of moisture in the firing atmosphere. The Mo microstructure had a significant influence on the critical volume fraction for conductivity in these cermets. Coarser alumina powder, finer Mo powder, and higher glass content promoted coalescence of Mo into conductive networks at lower metal contents. Drier firing atmospheres produced a more coarsened Mo microstructure with a slight decrease in the amount of network contiguity, causing an increase in the amount required for electrical percolation.

Diamond was deposited on smooth Si3N4-coated Si substrates using hot-filament chemical vapor deposition (CVD). Prior to diamond deposition, the substrates were pretreated under high temperature (700–900 °C) by decomposed pure hydrogen. The experimental results show that these pregrowth processes at a substrate temperature of 850 °C enhanced the diamond nucleation on Si3N4. This indicated that decomposed hydrogen acted on the substrate to produce active centers (<100 nm), which promoted diamond nucleation. It has also been suggested that Si3N4 coating can inhibit carbon transport into the substrate, and it is beneficial to the diamond nucleation.