Si3N4 sintered with Lu2O3 was exposed to 1 atm of oxygen and steam environments at 1200–1400 °C. The effects of additive and impurity species on the morphological development of the oxide layer were examined. Oxide layers grown on as-received samples in oxygen generally contained bubbles and cracks and underwent spallation due to the presence of an initial impurity-laden oxide layer. Oxide layers grown on as-received samples in steam exhibited layered morphology: a glassy outer layer and a cristobalite inner layer with a high population density of Lu2Si2O7 particles between. The Lu2Si2O7 particles accumulated at the interface led to extensive spallation of the upper oxide layer. Removal of the initial oxide by polishing resulted in improved oxidation resistance and oxide morphology in oxygen and in steam.

The valence and coordination structure of implanted Cu and Br ions were investigated by x-ray absorption fine structure spectroscopy in (2.4 MeV 6 × 1016 Br2+ ions cm−2+ 2 MeV 6 × 1016 Cu+ ions cm−2)-implanted silica glass. It was found that the implanted Cu and Br atoms were coordinated by oxygen atoms and silicon atoms, respectively, in as-implanted glass. After heating at 600 °C, at least two-thirds of the Cu atoms were coordinated by Br atoms without the formation of crystals. The γCuBr crystal was formed after heating to 1100 °C. It was deduced that the coordination structure of Cu and Br atoms depends on defects as well as thermochemical stability and mass transport processes.

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.

A 650 °C annealed thin film was found to be a single phase of SrBi2Ta2O9 (SBT) and showed the c-axis orientation without ultraviolet irradiation. The crystallinity and crystal orientation of the thin films were improved by ultraviolet irradiation using an ultrahigh-pressure mercury lamp (UHPML) or a low-pressure mercury lamp (LPML) under three conditions. In particular, the crystal orientation of the 650 °C annealed thin films dramatically changed by ultraviolet irradiation using a LPML at room temperature or using an UHPML at 150 °C. The 650 °C annealed SBT thin film prepared by ultraviolet irradiation using an UHPML at 150 °C showed a remanent polarization (Pr) of 4.3 μC/cm2 and a coercive electric field (Ec) of 101 kV/cm at 10 V.

Oxide melt solution calorimetric measurements were made to determine the enthalpy of formation of cubic-yttria-stabilized zirconia (c-YSZ) with respect to the oxides m-ZrO2 and C-type YO1.5. The enthalpy of formation can be fit either by a quadratic equation or by two straight line segments about the minimum near x = 0.40. The quadratic fit gives a strongly negative interaction parameter, Ω=-93.7 ± 12.0 kJ/mol, but does not imply regular solution behavior because of extensive short-range order. In this fit, the enthalpy of transition of m-ZrO2 to c-ZrO2, 9.7 ± 1.1 kJ/mol, is in reasonable agreement with earlier estimates and that of C-type to cubic fluorite YO1.5, 24.3 ±14.4 kJ/mol, is consistent with an essentially random distribution of oxide ions and anion vacancies in the high-temperature fluorite phase. The two straight-line segments give 6.1 ± 0.6 kJ/mol and 5.5 ± 2.5 kJ/mol for these transitions, respectively. The latter value would imply strong short-range order in cubic fluorite YO1.5. Clearly more complex solution thermodynamic descriptions need to be developed. The enthalpy of transition from the disordered c-YSZ phase to the ordered δ-phase at 25 °C was also measured and was 0.4 ± 1.6 kJ/mol. No energetic difference between the disordered c-YSZ phase and the ordered δ-phase underscores the importance of short-range order in c-YSZ. Enthalpy data were combined with Gibbs free energy data to calculate entropies of mixing. Using the quadratic fit, negative excess entropy of mixing in the cubic solid solution, relative to a system with maximum randomness on cation and anion sublattices, was found and was another indication of extensive short-range order in c-YSZ.

A new approach for the production of yttria-stabilized zirconia (YSZ) oxide buffer layers directly on metal rolling-assisted biaxially textured substrates (RABiTS) is described in this paper. This represents a significant advance over existing techniques and avoids the need for complicated steps to avoid substrate oxidation during direct deposition of oxides. Current densities of about 1 MA/cm2 have been achieved for YBa2Cu3O7-δ layers on the YSZ buffer, with an intermediate CeO2 layer. The process consists of reactive sputtering of a YxZr1−xN film directly on the RABiTS, which adopts its biaxial texture. This nitride film is then converted to YSZ via a thermal oxidation step. The YSZ films retain the texture of the nitride film (and of the RABiTS) through local syntaxy. In many cases, YSZ films exhibit improved biaxial texture over that of the RABiTS substrate. Nitrides can be sputter deposited at much higher rates relative to oxides, making the approach industrially scalable and economical.

A notched bimaterial bar bend test was applied to identify weak interfaces that influence the thermomechanical performance of solid-oxide fuel cell (SOFC) stacks with planar design. The experiments were focused on the weakest interface of the multilayered cells and on the rigid glass ceramic sealants between metallic interconnects of SOFC stacks. The fracture energies of these interfaces were determined. To test interfaces within the cells, they were glued to steel strips, and the notched cell was used as a stiffener in the test. The weakest part of the cells with composite cathodes was the interface between the functional part of the cathode and the remaining current collector. Values for the interfacial fracture energies of composite cathodes both freshly prepared and after aging were determined. Taking advantage of the crack extension within the anode from the notch-tip to the interface, the fracture energy of the oxidized and reduced anodes was calculated. Sandwich specimens with glass ceramic between the interconnect steel were used to determine the fracture energies for different glass ceramic–steel interfaces. Different combinations of ferritic steel and glass ceramic were tested. The fracture path developed partly along the interface and partly in the glass ceramic, which did not influence the fracture energy. However, a significant improvement of the fracture energy with annealing time was found.

Ni-based under-bump metallization (UBM) for flip-chip application is widely used in today's electronics packaging. In this study, electroplated Ni UBM with different thickness was used to evaluate the interfacial reaction during multiple reflow between Ni/Cu UBM and eutectic Sn–Pb solders in the 63Sn–37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure. During the first cycle of reflow, Cu atoms diffused through electroplated Ni and formed the intermetallic compound (IMC) (Ni1−x, Cux)3Sn4. After more than three times of reflow, Cu atoms further diffused through the boundaries of (Ni1−x, Cux)3Sn4 IMC and reacted with Ni and Sn to form another IMC of (Cu1-y, Niy)6Sn5. After detailed quantitative analysis by electron probe microanalysis, the values of y were evaluated to remain around 0.4; however, the values of x varied from 0.02 to 0.35. The elemental distribution of IMC in the interface of the joint assembly could be correlated to the Ni–Cu–Sn ternary equilibrium. In addition, the mechanism of (Cu1−y, Niy)6Sn5 formation was also probed.

A modified high-temperature arc furnace was used to produce carbon nanotubes from carbon black by a solid-state transformation without a catalyst. The layer of carbon nanotubes thus formed was nearly pure with only a minor amount of carbon black particles. The properties of these nanotubes were found to be very similar to those produced by the conventional arc synthesis. Based on this process, a mechanism for the growth of these nanotubes is proposed. In addition, field-emission properties of these nanotubes were comparable to the properties of arc-grown carbon nanotubes.

Grain-growth kinetics of a nanocrystalline 2 yttria-stabilized tetragonal zirconia polycrystals ceramic containing a silica-based glassy phase was determined at 1200 to 1600 °C. At short durations below 1300 °C, the slow grain growth was associated with zirconia dissolution for composition equilibration. The significant increase in the grain size started only after 10 h at 1400 °C or at shorter durations at higher temperatures. Clusters of the cubic grains formed at the two-phase field confirm the inhibited tetragonal grain growth to be independent of the cubic grains. The microstructure evolution during the tetragonal grain growth was interpreted in terms of grain coalescence. Grain growth was initiated by contact flattening and followed by grain-boundary diffusion through the grain-boundary glassy phase. Some aspects of cation diffusion within the viscous glass were also discussed.

Microstructural and magnetic characterization were undertaken on high-rate, high-temperature grown YBa2Cu3O7–δ (YBCO) films. The films were of approximately 1 μm thickness and were grown by pulsed laser deposition on (100) SrTiO3 using a high-power industrial laser at growth temperatures between 750 °C and 870 °C and at growth rates of up to 4 μm/min. Two YBCO layers with different c-lattice parameters were observed in the films, the higher c value occurring near the substrate interface and arising from cation disorder and oxygen nonstoichiometry, and the lower one near the film surface arising from cation disorder alone. BaCuO2 precipitates were present near the surface of the films, indicative of partial melting during growth. The amount of BaCuO2 increased with growth temperature. Epitaxial Y2O3 also formed in increasing amounts suggestive of a different partial melting reaction in the films compared to bulk YBCO, where Y2BaCuO5 coexists with liquid. Around 1 MA/cm2 values of high critical current density (Jc) were observed in the films, and the in-field Jc improved with growth temperature despite the fact that the superconducting transition width increased significantly.

To ascertain how the substrate influences the quality of AlOx films, AlOx films were grown on a bare glass and a ZnO-deposited glass in this study. By applying a ZnO interlayer before the AlOx deposition, AlOx films exhibited polycrystalline structure rather than amorphous as obtained by sputtering on a bare glass. For AlOx film on the ZnO-deposited glass, the transmission electron microscopy observation showed the coexistence of amorphous and polycrystalline structure, which reveals that the (122) plane in AlOx film is parallel to the surface of the substrate. The grains of the AlOx film grown on a ZnO-deposited glass comprising many small crystallites aggregated with sizes varying between 38 and 54 nm with irregular grain shapes. Besides, the ZnO interlayer with different deposition parameters had a significant effect in the diffusion interface between AlOx and ZnO. The ZnO interlayer could improve the optical transmission of AlOx films, especially when ZnO films are prepared with a high power of 200 W. Therefore, the glass/ZnO may be a good alternative substrate for producing high-quality AlOx films by controlling the epitaxial grain growth. The AlOx films grown on ZnO-deposited glasses have very good qualities in terms of crystallinity and optical properties.

Metal contamination in Si and SiO2 films deposited by plasma-enhanced chemical vapor deposition (PECVD) in the fabrication of low-temperature poly Si thin-film transitor was investigated. Aluminum was the major metal impurity to have the highest concentration. Segregation of Al was always observed in the films deposited at temperatures above 400 °C. The impurity level in the segregated region was 1018 ∼ 1020 atoms/cm3 for Al, while the concentration in matrix was about 1016 atoms/cm3. From the transmission electron microscopy image, the Al segregated region contains small-size Al precipitates. Although the Al impurity level of 1016 atoms/cm3 did not cause any serious degradation of device performance, the level of 1018 atom/cm3 and higher can induce a fatal degradation of the threshold voltage. This study revealed that the Al originated from the PECVD chamber, carbon precipitates provided the preferred sites for Al precipitates, and the solubility and diffusivity of Al in Si accelerated the segregation of Al.

The crystallographic texture, orientation relationships, coherency stress, and thermal stability of sputter-deposited Ni/Ni3Al multilayered thin films were studied as a function of bilayer period (Λ) as well as processing parameters such as substrate type, deposition temperature, and prebake conditions. Deposition onto oxidized Si or single-crystal Cu(001), NaCl(001), or KBr(001) substrates near room temperature produces multilayers with a [111] crystallographic texture along the Ni/Ni3Al interface normal and a disordered face-centered cubic structure for the Ni3Al phase. In contrast, deposition at 673 K onto NaCl(001) or KBr(001) substrates that are prebaked in vacuum at 693 K produces a chemically ordered L12 structure for the Ni3Al phase and (001) epitaxial growth. X-ray diffraction measurements of (001) multilayers with equal volume fraction of Ni and Ni3Al reveals a transition from a nearly incoherent state at Λ=40 nm to a semicoherent one at Λ 40 nm. Remarkably, (001) multilayers were observed to solutionize at 1373 K, which is approximately 100 K below that predicted by the Ni–Al phase diagram.

A multistep technique has been developed for the generation of metallic/alloy nanoparticles coated with amorphous silica. As a proof of concept, an inert-gas blown-arc geometry was used to create nanoparticles from a bulk nickel source, and silica coating formation was accomplished via tetraethyloxysilane (TEOS) decomposition over the nanoparticles in an adjacent chemical vapor deposition chamber. The composite particles exhibit resistance to hydrochloric acid attack over extended times, thereby confirming the protective nature of the silica coating, and magnetic measurements indicate a superparamagnetic transition temperature of 41 K. TEOS flow rate was found to have a profound effect on particle morphology, and individually coated dispersed particles were observed for the intermediate flow rate studied. These results, combined with the well-established field of silica functionalization, offer the possibility that a variety of industrially significant coated magnetic nanostructures may be synthesized with this versatile approach.

We numerically simulated the current density distribution in electrically nonlinear varistor material containing geometrically simple inclusion defects. Nonconductive spheres and disks, which resemble inclusion shapes observed in chemically prepared varistor material, were investigated. Current densities near perfectly conductive spheres and rods were also computed to gain insight into observed electrical degradation phenomena. These defects were assumed to be much larger than the characteristic size of the zinc oxide (ZnO) grain structure, and our computational method treated the varistor material as electrically isotropic. Results showed strong, localized concentrations of current with either perfectly conductive or nonconductive inclusions, and a dependence on the density of the conductive defects. The small spatial extent of strong current intensification may help to explain the stepwise electrical degradation we have observed when a failing ZnO varistor is subjected to high-power electrical pulses.

Based on a structure model of mixture of phases, the crystal structure analysis of (Ba1−xLax)[Mg(1+x)/3Nb(2−x)/3]O3 (BLMN) (x = 0.9 and 1.0) by Rietveld refinements was carried out. The pure La(Mg2/3Nb1/3)O3 (LMN) and BLMN (x=0.9) actually consist of a two-phase mixture rather a single phase. One is Fm-3m, which is cubic and 1:1 ordered and the other is P21/n, which is monoclinic and has both 1:1 ordering and the antiphase and inphase tilting of oxygen octahedra with a−a−c+. The weight fraction of the Fm-3m phase is 17.5% at x=0.9 and further decreases to 7.5% in pure LMN. Meanwhile, that of the P21/n phase is 82.5% at x =0.9 and further increases to 92.5% in pure LMN. The I4/m phase, which is present as a minor phase from x=0.3 to 0.7, disappeared when x≥0.9. The abrupt change of the x-ray diffraction pattern at x=0.9 is caused by a change of major phase from Fm-3m to P21/n phase in the matrix.

We processed coarse-grained Ti and equal-channel angular pressing (ECAP) processed ultrafine-grained (UFG) Ti into 20-μm-thick Ti foils by cold rolling and intermediate annealing. The foils produced from rolling the UFG Ti exhibit a homogeneous nanostructure, while foils produced from rolling the coarse-grained Ti exhibit heterogeneous structures with a mixture of nanostructured regions and coarse-grained regions. The former foils also have higher strength and ductility and exhibit uniform deformation over a larger strain range at room temperature than the latter ones. This work demonstrated the advantage and viability of producing nanostructured Ti foil by rolling ECAP-processed UFG Ti stock.

Colloidal copper particles with a high degree of crystallinity were obtained by heating solutions of copper(II) acetate in ethylene glycol (EG) and tetraethylene glycol (TEG). The formation mechanism of copper particles involved first the formation of sparingly soluble nano-sized copper(I) oxide, which aggregated into uniform spheres. On prolonged heating the Cu2O particles were reduced to nano-sized copper crystallites followed by their sintering to colloidal metal. The conversion of the copper(I) oxide to metallic copper proceeds uniformly within the body of each particle.