Diamond composites with nanocrystalline cubic silicon carbide bonding were sintered from diamond/amorphous silicon mixtures under high pressure and high temperature (p = 5 GPa and temperatures up to 1673 K). Differential scanning calorimetry, ex situ x-ray, and Raman spectroscopy investigations showed that amorphous silicon partially transformed into nanocrystalline silicon at 873 K under 5 GPa. This was followed by the formation of nanocrystalline silicon carbide from the reaction between the silicon and diamond after silicon melting. Refinement of the x-ray diffraction patterns of composites with the Rietveld method revealed that considerable microstrain (0.3–0.5%) remained within the nanocrystalline silicon carbide grains. Small strain (0.1–0.2%) was observed in the compacted diamonds, but after the reaction they became almost strain free (<0.1%). Enhanced fracture toughness was obtained for hybrid composites compared to liquid-infiltrated composites.

Concurrent synthesis of titania-carbon nanoparticles (up to 52 wt.% in C) was studied in a diffusion flame aerosol reactor by combustion of titanium tetraisopropoxide and acetylene. These graphitically layered carbon-coated titania particles were characterized by high-resolution transmission electron microscopy (HRTEM), with elemental mapping of C and Ti, x-ray diffraction (XRD), and nitrogen adsorption [Brunauer-Emmett-Teller (BET)]. The specific surface area of the powder was controlled by the acetylene flow rate from 29 to 62 m2/g as the rutile content decreased from 68 to 17 wt.%. Light blue titania suboxides formed at low acetylene flow rates. The average XRD crystal size of TiO2 decreased steadily with increasing carbon content of the composite powders, while the average BET primary particle size calculated from nitrogen adsorption decreased first and then approached a constant value. The latter is attributed to the formation of individual carbon particles next to carbon-coated titania particles as observed by HRTEM and electron spectroscopic imaging.

The stability of titanium oxide nanotube arrays at elevated temperatures was studied in dry oxygen as well as dry and humid argon environments. The tubes crystallized in the anatase phase at a temperature of about 280 °C irrespective of the ambient. Anatase crystallites formed inside the tube walls and transformed completely to rutile at about 620 °C in dry environments and 570 °C in humid argon. No discernible changes in the dimensions of the tubes were found when the heat treatment was performed in oxygen. However, variations of 10% and 20% in average inner diameter and wall thickness, respectively, were observed when annealing in a dry argon atmosphere at 580 °C for 3 h. Pore shrinkage was even more pronounced in humid argon environments. In all cases the nanotube architecture was found to be stable up to approximately 580 °C, above which oxidation and grain growth in the titanium support disrupted the overlying nanotube array.

The relationship between the microwave dielectric property and crystal structure of Nd2(Ba1−xSrx)ZnO5 solid solutions was investigated using bond valence theorem and first principle method (DV-Xα method). The evaluation of the covalence characteristics of cation–oxygen bonds revealed that as the x value increased, the covalence characteristics of the M–O (M = Ba and Sr) bonds in the MO10 polyhedron decreased while those of the Zn–O(2) bonds in the ZnO4 tetrahedron increased. From the DV-Xα method, it was found that the 3d electrons of the Zn2+ ion are closely related to the strong covalence characteristics of the Zn–O(2) bonds. The dielectric constants were approximately constant over the whole composition; this result is considered to relate to the decrease in the covalence characteristic of the M–O bonds. The quality factors increased from 4915 to 25,836 GHz, and the grain growth of the solid solutions are considered to improve the Q × f values.

Powders of (1 − x) Pb(Fe1/2Nb1/2)O3-xPbTiO3 (PFN-PT) with x = 0.00, 0.10, 0.13, 0.15, 0.20, and 0.25 were prepared by the conventional solid-state route. Structure of PFN-PT was tetragonal for x [H33356] 0.10, which indicates that the morphotropic phase boundary (MPB) may be between 0 < x < 0.10. The nature of phase transition in PFN-PT changed from diffuse ferroelectric to relaxor ferroelectric to normal ferroelectric on increasing the PT content. The effect of the PT content and sintering temperature on barrier layer formation in the PFN-PT system was studied using complex impedance spectroscopy. With increasing PT content, the possibility of the barrier layer formation decreased while with increasing sintering temperature, the barrier layer formation was promoted.

Mesoporous crystalline SnO2 was synthesized by using templating process with cetyltrimethylammonium bromide as the template, combined with a pretreatment process of hexamethyldisilazane vapor prior to thermal crystallization. The combined process resulted in crystalline SnO2 exhibiting large pore volumes and surface areas that cannot be achieved by either of the processes alone, or by the conventional sol-gel process. Fully crystallized SnO2 powder with a pore volume of approximately 0.2 cc/g, a surface area of 220 m2/g, and mesopores mainly of 5 nm in diameter were obtained after heat treatment at 500°C.

Structural, mechanical, and electrical properties were examined for C60 whiskers, high-pressure sintered C60 whiskers, and C60 powder. A high density of dislocations was observed in the C60 whiskers, and the C60 whiskers with diameters of a few hundred nanometers were found to be flexible. Although both the specimens sintered under the same condition showed similar surface x-ray diffraction profiles with a strong accumulation of [110]tr orientation, the sintered C60 whiskers showed a higher micro-Vickers hardness and an electrical resistivity four orders of magnitude lower than that of the sintered C60 powder.

Preparation of dense and phase-pure Ba2Ti9O20 is generally difficult to achieve using a solid-state reaction, due to the presence of several thermodynamically stable compounds in the vicinity of the desired composition. This work investigated the effects of various additives (TiO2, MnO, and ZrO2) on the densification, microstructural evolution, phase stability, and dielectric properties of Ba2Ti9O20. Ceramics with theoretical density of ≥95% were achieved in all cases after sintering at 1300 °C. A pure Ba2Ti9O20 phase was obtained by treating the material with TiO2 additions (≤5.6 wt.%) and sintering at temperatures ranging between 1200 and 1350 °C. Ba2Ti9O20 is a nonstoichiometric compound that can accommodate an excess amount of TiO2. As the temperature was increased, pure Ba2Ti9O20 partially decomposed and formed a mixture of BaTi4O9 and Ba2Ti9O20. The ceramic with excess TiO2 sintered at 1390 °C possessed a higher permittivity and a lower quality factor due to the larger grain size and lower density. For ceramic with the addition of ZrO2 (≤6 wt.%), pure Ba2Ti9O20 phase was obtained after sintering between 1200 and 1390 °C, and the quality factor was improved. The decomposition temperature of the Ba2Ti9O20 phase was greater than 1390 °C. For sintering temperatures ≥1350 °C, the extent of Ba2Ti9O20 phase decreased with MnO additions. As the MnO content reached 0.5 wt.%, only BaTi4O9 and TiO2 phases existed, suggesting a decrease in the decomposition temperature of Ba2Ti9O20 with the addition of MnO. The microwave properties of the ceramics degraded significantly at the sintering temperature of 1390 °C.

In a previous computer-simulation experiment, the accumulation of damage in silicon carbide (SiC) from the overlap of 10 keV Si displacement cascades at 200 K was investigated, and the damage states produced following each cascade were archived for further analysis. In the current study, interstitial clustering, system energy, and volume changes are investigated as the damage states evolve due to cascade overlap. An amorphous state is achieved at a damage energy density of 27.5 eV/atom (0.28 displacements per atom). At low-dose levels, most defects are produced as isolated Frenkel pairs, with a small number of defect clusters involving only four to six atoms; however, after the overlap of five cascades (0.0125 displacements per atom), the size and number of interstitial clusters increases with increasing dose. The average energy per atom increases linearly with increasing short-range (or chemical) disorder. The volume change exhibits two regimes of linear dependence on system energy and increases more rapidly with dose than either the energy or the disorder, which indicates a significant contribution to swelling of isolated interstitials and antisite defects. The saturation volume change for the cascade-amorphized state in these simulations is 8.2%, which is in reasonable agreement with the experimental value of 10.8% in neutron-irradiated SiC.

The crystallinity dependence of the microwave dielectric losses in (Ba,Sr)TiO3 thin films was investigated. The sputter-deposition temperatures were altered to vary the level of thin-film crystallinity on a Pt/Si substrate. The dielectric losses (tan δ) were measured up to 6 GHz without parasitic (stray) effects by using a circular-patch capacitor geometry and an equivalent-circuit model. The microwave dielectric losses increased from 0.0024 ± 0.0018 to 0.0102 ± 0.0017 with increasing crystallinity. These deteriorated dielectric losses showed a good correlation with the symmetry-breaking defects, as confirmed by Raman spectra at approximately 760 cm−1, inducing microscopic polar regions above the Curie temperature of the bulk (Ba0.43Sr0.57)TiO3.

Structural stability of a Cu60Ti20Zr20 metallic glass under pressure up to 4.5 GPa was investigated by x-ray diffraction. The sample exhibited a supercooled liquid region of 33 K and a ratio of the glass-transition temperature to the liquidus temperature of 0.63. The glass crystallized in two-step transformation processes in the pressure range of 0–4.5 GPa; the first was a primary reaction to form a Cu51Zr14-type structure crystalline phase with a spacing group P6/m (175) and lattice parameters a=11.235 Å and c=8.271 Å, and then the residual amorphous phase crystallized into a MgZn2-type structure crystalline phase with a spacing group P63/mmc (194) and lattice parameters a=5.105 Å and c=8.231 Å. Both crystallization temperatures increased with pressure having a slope of 19 K/GPa. The increase of the first crystallization temperature with increasing pressure in the glass can be explained by the suppression of atomic mobility. No significant structural change was detected in the Cu60Ti20Zr20 glass annealed in vacuum at 697 K for 1 h as compared to the as-prepared sample from x-ray diffraction measurements.

Several chemical–mechanical planarization characterization test wafers were polished to understand the polishing mechanism of the fixed abrasive process. Oxide thickness removal in the “active” (up) and the “recessed” (down) regions of the wafer was monitored for different times of polish. It was found that there was no significant removal in the recessed areas until the step height was reduced to about 100 Å, and the polish rate in the active area decreased rapidly once this critical step height had been attained. At this critical step height, the polish rate of the down areas started to increase and approached that of the up area, with both eventually reaching the negligibly low removal rate of the blanket wafer. The drop in the polish rate of the up area, after planarity had been attained, was fitted to an exponential model.

The effects of the electrokinetic behavior of abrasive ceria particles suspended in an aqueous medium and the deposited plasma-enhanced tetraethylorthosilicate (PETEOS) and chemical vapor deposition (CVD) Si3N4 films on chemical mechanical planarization (CMP) for shallow trench isolation were investigated. The colloidal characteristics of ceria slurries, such as their stability and surface potential, in acidic, neutral, and alkaline suspensions were examined to determine the correlation between the colloidal properties of ceria slurry and CMP performance. The surface potentials of the ceria particles and the PETEOS and CVD Si3N4 films in an aqueous suspending medium were dependent on the pH of the suspending medium. The differences in surface charges of ceria particles and the PETEOS and CVD Si3N4 films have a profound effect on the removal rate and oxide-to-nitride selectivity of CMP performance.

The effect of Mg in Ag(Mg)/SiO2/Si multilayers on the adhesion, passivation, and resistivity following vacuum annealing at 200–500 °C has been investigated. The annealing of Ag(Mg)/SiO2/Si multilayers produced surface and interfacial MgO layers, resulting in a MgO/Ag/MgO/SiO2/Si structure. The formation of a surface MgO/Ag bilayer structure provided excellent passivation against air and CF4 plasma chemistry. In addition, the adhesion of Ag to SiO2 was improved due to the formation of an interfacial MgO layer resulting from the reaction of segregated Mg with SiO2. However, the negligible solubility of Si in Ag prevented the dissolution of free silicon into the Ag(Mg) film produced from the reaction Mg + SiO2 = MgO + free Si, which in turn limited the reaction between Mg and SiO2, which led to a decrease in the adhesion of Ag to SiO2 at the higher temperature. The use of an O2 plasma prior to Ag(Mg) alloy deposition on SiO2 produced an oxygen-rich surface on the SiO2, which allowed for the enhanced reaction of the segregated Mg and SiO2 at the surface, thus resulting in markedly increased adhesion properties.

Simulated body fluid (SBF) has been widely used for assessment of bioactivities of different materials. Those kinds of conventional SBF (C-SBF) have a higher Cl− concentration and a lower HCO3− concentration than those of human blood plasma. Therefore, a revised simulated body fluid (R-SBF), with ion concentrations including those of Cl− and HCO3− exactly equal to those of human plasma, was recently developed. Porous glass-ceramic was used as the testing material to evaluate the two kinds of SBF. Results showed that C-SBF is considered more active than R-SBF because the porous glass-ceramic had a higher apatite formation rate on its surface,while R-SBF is considered to simulate the human body fluid more precisely than C-SBF.

A single glassy phase of V45Zr22Ni22Cu11 alloy powders was synthesized by milling the elemental alloying powders in an argon atmosphere using a low-energy ball-milling technique. During the early and intermediate stages of milling, the atoms of Zr, Ni, and Cu migrated and diffused into the V (base material) lattice to form a body-centered-cubic (bcc) solid-solution, which transformed into a glassy phase with the same composition upon annealing at 850 K for 300 s in an argon atmosphere differential scanning calorimeter (thermally-enhanced glass formation reaction). As the milling time increased, the powders were subjected to continuous defects and lattice imperfections that led to a gradual change in the free energy so that solid-solution phase was transformed (mechanically enhanced glass formation reaction) to another metastable phase (glassy). Toward the end of the milling processing time, the bcc solid-solution transformed completely into a single glassy phase with the same composition. The glass-transition temperature, the crystallization temperature, and the enthalpy change of crystallization of the fabricated glassy powders were 741 K, 884 K, and −2.18 kJ/mol, respectively. This fabricated glassy alloy showed a wide supercooled liquid region (143 K) of metallic glassy alloy. The glassy powders were compacted in an argon gas atmosphere at 864 K with a pressure of 780 MPa using a hot-pressing technique. The consolidated sample was fully dense (above 99.2°) and maintained its chemically homogeneous glassy structure. The Vickers microhardness of the consolidated glassy V45Zr22Ni22Cu11 alloy was measured and found to be in the range between 6.89 GPa to 7.02 GPa.

Biaxially aligned indium tin oxide (ITO) thin films were prepared by an ion-beamassisted deposition (IBAD) process at room temperature. Films with a transmittance at 550 nm of 90% and an electrical resistivity of 1.1 × 10−3 Ωcm for 300 and 250 nm thickness were obtained. Investigations of the texture evolution during IBAD film growth were carried out and compared to the well-established texture development in yttria-stabilized zirconia. An in-plane texture of 12.6° full width at half-maximum (FWHM) for a 1-μm-thick IBAD-ITO film was achieved. The quality of these films as electrically conductive buffer layers for YBa2Cu3O7-δ (YBCO) high-temperature superconductors was demonstrated by the subsequent deposition of high-currentcarrying YBCO films by thermal co-evaporation using a 3–5-nm-thick Y2O3 interlayer.A Jc of 0.76 MA/cm2 (77K, 0 T) was obtained for a 1 × 1 cm sample with ITO of 20° FWHM.

We report on radiotracer diffusion measurements in metallic bulk-glass-forming Pd-Cu-Ni-P alloys. The Pd-Cu-Ni-P system, with its high stability against crystallization, allows diffusion measurements from the glassy state to the equilibrium melt for the first time. Serial sectioning was performed by grinding and ion-beam sputtering. The time and temperature as well as mass dependence, expressed in terms of the isotope effect E, of codiffusion were investigated. In the glassy state as well as in the deeply supercooled state below the critical temperature Tc, where the mode-coupling theory predicts a freezing-in of liquidlike motion, the measured very small isotope effects indicated a highly collective hopping mechanism. Below Tc, the temperature dependence showed Arrhenius-type behavior. Above Tc, the onset of liquidlike motion was evidenced by a gradual drop of the effective activation energy, resulting from the decay of hopping barriers, and by the validity of the Stokes-Einstein equation, which was found to break down below Tc. This strongly supports the mode-coupling scenario. Isotope effect measurements, which have never been carried out near Tc in any material, showed atomic transport up to the equilibrium melt to be far away from the hydrodynamic regime of uncorrelated binary collisions. The latter appears to be a prerequisite of excellent glass-forming abilities.

MgO single crystals and thin films were intentionally hydrated to determine the critical factors affecting the hydration behavior. The degree of hydration was affected by the crystallographic orientation in the initial stages. The (111) plane showed a higher tendency to hydrate than (100). The shape of the hydration clusters also differed according to the orientation of MgO single crystals. After long-term hydration, the density and grain size appeared to influence the hydration along with the orientation. On low-density thin films, Mg atoms are easily supplied to the surface, which induces large hydration clusters. As the grain boundary area increased, the number of nucleation sites for the formation of hydration clusters increased, which increases the number of clusters. Hydration also occurred in the inner part of thin films. The density of thin films is the most important property in this case because it governs the diffusion of Mg atoms, water, and OH through the thin films.

Nb-doped Bi4Ti3O12 (Nb-BIT) ferroelectric thin films were prepared in the presence of a nonionic surfactant (pluronic P123) added as an additive to the sol solution and by rapid thermal annealing (RTA). The film annealed at the relatively low temperature of 600 °C was well crystallized and showed good ferroelectricity. The switching charge of capacitors with polarization reversal rapidly increased with a large amplitude and low frequency of the applied pulse, and gradually decreased with a small amplitude and high frequency. The remanent polarization (2Pr) after subjecting the Nb-BIT capacitors to 108 read/write cycles was 46 μC/cm2, which is remarkably higher than 20 μC/cm2 observed in the initial state. These phenomena seem to appear by the presence of space charges trapped after heat treatment by the RTA process.