Nanosized particles of γ–Fe2O3 were prepared by heat treatment of the precipitates, obtained from a homogeneous solution of stearic acid and hydrated iron(III) nitrate. The compositional and thermal characteristics of the precipitates were studied with the aid of infrared spectroscopy and differential scanning calorimetry. The x-ray diffraction and small-angle x-ray scattering investigation shows that γ–Fe2O3 nanoparticles with narrow size distribution can be prepared successfully by this route.

The electrical conduction behavior of sputter-grown (Ba,Sr)TiO3 thin films having IrO2 electrodes were studied under the assumption of a fully accumulated film having a negative space charge density of 1 × 1019 cm−3 at 25 °C. The negative space charge decreased the actual field strength in the film and resulted in a decreasing leakage current with increasing film thickness at a given applied field. The current conduction in a very low field, roughly less than 150 KV/cm, showed a linear current density–voltage (J–V) behavior at 25 °C. From that field to about 420 KV/cm, the bulk-limited Poole–Frenkel mechanism controlled the overall conduction property at room temperature. Under high field strength, from 420 KV/cm to 1 MV/cm, the interface-limited thermionic field emission mechanism was dominant. The dielectric constant obtained from Poole–Frenkel fitting was approximately 300 ± 50 at 25 °C, which was in qualitative agreement with the value obtained from low-frequency capacitance measurements. The detailed mechanisms of the linear and nonlinear field-dependent emission conductions were discussed with reference to the direction of band bending, not to the carrier concentration.

Nanocrystalline Zn was prepared by cryomilling (mechanical attrition at liquid nitrogen temperature). Differential scanning calorimetry (DSC), x-ray diffraction, and transmission electron microscopy were used to study the structural changes and grain size distribution with milling time and subsequent annealing. Maxima in both stored enthalpy (for the low-temperature DSC peak) and lattice strain on the Zn basal planes were observed at the same milling time. Dislocation density on the basal planes is proposed as a major source for lattice strain and the measured stored enthalpy. The released enthalpy that might be due to grain growth is very small.

A new reliable embedded atom method potential for hydrogen in body-centered-cubic (bcc) iron is developed by fitting not only to the properties of hydrogen in a perfect bcc iron lattice but also to the properties of hydrogen binding to vacancies. The validity of the potential is examined by calculating the properties of hydrogen trap binding to surfaces and dislocations that are in good accordance with the experiments. A brief application of the potential by molecular dynamic simulation reveals that hydrogen accumulated ahead of the crack tip induces serious hydrogen embrittlement.

Hydrodynamic cavitation was shown to be a powerful tool for the synthesis of nanostructured catalysts, ceramics, and piezoelectrics in high phase purities. The macro-, micro-, and nano- properties of solid-state materials could be controlled through adjusting the cavitational regime during synthesis by simple mechanical adjustment. The synthesis of nanostructured titania, piezoelectrics, perovskites, supported and unsupported cobalt molybdates, and Pd and Ag supported on alumina illustrate changes in morphology and size of crystals, growth in a preferred orientation of crystallites, and control of crystallographic strain and size compared to classically prepared materials. The high shear and cavitational forces during synthesis induce micro-strain into the materials and are a function of the Reynolds and cavitation numbers.

Commercial micrometer Al2O3 powder was sintered at 1550 °C under a mechanical pressure of 30 MPa by pulse electric current sintering (PECS). Microstructure observation was performed on polished, thermal-etched cross sections parallel to the direction of mechanical pressure. Platelike Al2O3 grains formed when the powder was heated at a heating rate of 5 °C/min, while a heating rate of 200 °C/min resulted in equiaxed grains. These results indicated that PECS is an effective approach to hinder grain growth by application of a higher heating rate. However, Al2O3 grains at the upper edge were larger than those at the side edge of the samples in both cases. It implied that there were different temperatures at the upper edge and the side edge of the Al2O3 powder compacts during the PECS process.

A combustion synthesis method was developed for synthesis of AlN powder. Al powder and small amounts of NH4Cl were thoroughly mixed and placed in low-melting-point containers made of a thin, perforated aluminum sheet. The combustion reaction was ignited by heating the top surface of the powder stack, and the aluminum container was converted completely to AlN during the combustion reaction. High product yields were obtained under N2 pressures of 0.2–0.5 MPa. The product was composed of a dense outer portion and a loose inner portion. Effects of several process parameters on the product yield were investigated and discussed.

SrBi2Ta2O9 (SBT) films were prepared on Pt/TiO2/SiO2/Si substrates at 750 °C in oxygen by the metalorganic decomposition method. SBT film capacitors were postannealed in Ar (N2) at 350–750 °C and then reannealed in O2 at 750 °C. Effects of annealing atmosphere on the structure, morphology, and ferroelectric properties have been investigated systematically. The composition analyses indicate Ar- or N2-annealing at 750 °C leads to Bi evaporation and oxygen loss. Above 550 °C 100% Ar or N2 postannealing, the remnant polarization decreases and the coercive field increases significantly. The subsequent O2 recovery can hardly rejuvenate the electrical properties. The result is different from that with the effective O2 recovery in forming gas processing (annealing in an atmosphere containing 5% hydrogen). The possible origin and mechanism is discussed and proposed.

The depth of photocuring for a model resin system was investigated as a function of photoinitiator concentration. Direct measurements of gel thickness were made from thin films of cross-linked multifunctional methacrylate monomer. The monomer, 2,2-bis{4-[2-hydroxy-3-(methacryloxy)propoxy]phenyl}propane, was polymerized in a solution of trichloroethylene with an ultraviolet laser light source at 325 nm. The monomer solutions were photocured using varying levels of both photonic energy and photoinitiator concentration. An optimal photoinitiator concentration that maximized the gel cure depth was observed. Additionally, two regimes were shown to exist in which the shrinkage (upon solvent removal) was minimized or maximized. A model was developed to probe the physics of the system. Good agreement with experiment was obtained, and the model may be employed to predict both the existence and location of the optimal photoinitiator concentration and the corresponding cure depth. The study showed that photoinitiator plays a significant role in controlling the quality and performance of the formed gel network, with special regard to thickness of cured layers. This has potential application to fields as diverse as industrially cured coatings and dental fillings, and more generally, 3-dimensional rapid prototyping techniques.

This paper examined the room-temperature thermal and mechanical properties of a mixed conducting perovskite La1−xSrxCr0.2Fe0.8O3 (x = 0.2 to 0.8). Powders were made by the combustion-synthesis technique and sintered at 1250 °C in air. Sintered density, crystal phase, and grain size were characterized. Linear thermal expansion in air was also tested. Young's and shear moduli, microhardness, indentation fracture toughness, and biaxial flexure strength were determined. It was found that the linear coefficient of thermal expansion increased with increasing Sr content, while elastic modulus appeared to decrease with increasing Sr content. Young's modulus of 128 to 192 GPa and shear modulus of 51 to 74 GPa were measured. A biaxial flexure strength of 243 MPa was measured for the lowest Sr content batches. Batches with higher Sr concentrations (x = 0.6 to 0.8) showed extensive cracking. Indentation toughness showed a decrease with increasing Sr content. In addition, fractography was used to characterize the critical flaw and the fracture mode.

The optical constants of Si/ZnO composite films grown on quartz glass substrates were determined in the spectral range 1.5–5.0 eV by spectroscopic ellipsometry using a rotating-analyzer ellipsometer. The structure of the samples was modeled by a two-phase (substrate–film) model, and the optical functions of the film were parameterized through different effective medium approximations. The results allowed us to estimate the microstructural film parameters, such as film thickness, the volume fractions of each of the constituents, and optical constants.

Room-temperature scanning probe microscopy was used to generate out-of-plane deformation maps around Cu vias and polyimide mesas in single-level Cu–polyimide damascene interconnect structures subjected to a room-temperature to 350 °C thermal cycle. The deformation maps are obtained by taking the difference between the images obtained before and after thermal processing. The deformation of the Cu is shown to be highly heterogeneous on the submicrometer scale. Direct evidence of Cu–Ta interfacial sliding, Cu–Cu grain boundary sliding, and diffusion creep is presented. The direction of Cu–Ta sliding is shown to depend on polyimide mesa size. A hot-stage atomic force microscope was used to show that hillock/extrusion growth occurs at temperatures between 130 and 180 °C. We propose that this hillock/extrusion growth is correlated with dips in stress–temperature plots for blanket, uncapped Cu films in the same temperature range and that the absence of dips for nitride-capped Cu films is due to suppression of the hillock/extrusion growth.

The fretting wear of sulphur-deficient MoSx coatings with different crystallographic orientations has been investigated in ambient air of controlled relative humidity. The coefficient of friction and the wear rate of MoSx coatings sliding against corundum depend not only on fretting parameters like contact stress, fretting frequency, and relative humidity, but also strongly on the crystallographic orientation of the coatings. For randomly oriented MoSx coatings, the coefficient of friction and the wear rate increased significantly with increasing relative humidity. In contrast, basal-oriented MoSx coatings were less sensitive to relative humidity. The coefficient of friction of both types of MoSx coatings decreased on sliding against corundum with increasing contact stress and decreasing fretting frequency. A correlation between dissipated energy and wear volume is proposed. This approach allows detection in a simple way of differences in fretting wear resistance between random- and basal-oriented MoSx coatings tested in ambient air of different relative humidity.

Like many other oxides, MnZn ferrite shows a considerably decreased strength in a humid environment. Conventionally one explains this behavior by subcritical crack growth, i.e., a kinetic effect affecting the oxygen–metal bond breaking rate at the crack tip via a reaction with water. The dissociation of water in a proton and hydroxyl ion is considered as crucial. However, it appears that also other gases have a detrimental effect on the strength. In this paper the effect of H2O, H2S, NH3, NO, and CO on the strength of MnZn ferrite have been studied experimentally. For water a clear minimum in strength occurs at relative low partial pressure. For the other gases the data also indicate a minimum. An adsorption model taking into account the presence of competitive adsorption mechanisms, involving dissociative and nondissociative adsorption of the adsorbate and the (non)dissociative adsorption of the ever present N2, is presented. This model can explain the experimentally observed features well. Although kinetic effects induce subcritical crack growth in MnZn ferrites, it is concluded that adsorption is an important strength lowering effect for MnZn ferrite when exposed to active gases.

The metalorganic chemical vapor deposition of very thin (<50 nm) Pb(Zr,Ti)O3 (PZT) thin films was performed for high density (>32 mega bit) ferroelectric memory devices. The growth temperatures were set between 450 and 530 °C to obtain a smooth surface morphology and prevent damage to the underlying reaction barrier layer. The average grain size of a 50-nm-thick film on a Pt electrode was about 34 nm with a size distribution (σ2) of 11 nm. These values are much smaller than the sol-gel-derived PZT films (55 and 25 nm, respectively). Very thin films with a thickness of approximately 30 nm were prepared at wafer temperatures ranging from 500 to 525 °C. Even with the very small thickness, the films showed good ferroelectric properties with a typical remanent polarization from 10 to 15 μC/cm2 and an extremely low coercive voltage of 0.3 V. However, the leakage current density was rather high resulting in nonsaturating polarization versus voltage curves. Even though good ferroelectric properties were obtained, the formation of PtxPby alloys on top of the Pt electrode was consistently observed. This precludes the reliable control of film composition and electrical performance. The adoption of an Ir electrode successfully eliminated intermetallic alloy formation and resulted in better and reproducible process control. A 50-nm-thick PZT film on an Ir/IrO2/SiO2/Si substrate also showed a reasonable ferroelectric performance.

The sessile-drop method and high-temperature small-angle x-ray diffraction technique were used to characterize the density of liquid Al–Si alloys with Si content C = 0 to 22 wt%. A distinct abnormal volume expansion of the hyper-eutectic melts was identified just above the liquidus (within TL–Tk) during the heating sequence (h.s.), which is irreversible during the cooling sequence (c.s.). This phenomenon is explained by the segregation of Si atoms from the supersaturated “quasi-eutectic” structure and formation of silicon clusters in the superheated melt. In addition, a pre-peak in the x-ray diffraction spectrum of Al–14% Si melt was observed at 850 °C, which is associated with the silicon clusters. The pre-peak remains when the superheated melt is cooled down to the liquidus (670 °C); this result is in accord with the density measurements.

In this paper it is shown that the initial stages in the laser-induced roughening in silicon is independent of the atmosphere used, whether it is Ar, vacuum, or SF6. It is also shown that the morphology that results after a few hundred laser pulses strongly depends on the crystallographic orientation of the surface. The morphological features that appear in this first stage have been related to the nature of the solidification process that follows laser melting. A second stage in the roughening process with a dramatic change in morphology takes place when a surface with deep depressions and hills is further irradiated in SF6. Very deep etching occurs in the depressions promoting the formation of microholes that with further irradiation lead to cone formation. It is further shown that the distance between microholes is equal to the distance between the depressions that formed as the initial perturbations developed. Then the wavelength of the initial perturbation and by extension the distance between microholes has been estimated.

Potassium lithium niobate (KLN) powders and thin films were prepared from metalorganic compounds through the sol-gel process. A homogeneous and stable KLN precursor was synthesized by mixing the metal ethoxides. Powder gels were obtained through the hydrolysis of the solution by exposing it to the ambient atmosphere. Thin films were deposited on Si, SiO2/Si, and fused quartz by a spin coating technique. The pyrolysis and crystallization of KLN powders and films were investigated through the methods of differential thermal analysis, thermogravimetric analysis, x-ray diffraction, and Raman scattering spectroscopy. The results revealed that both KLN powders and films could crystallize into a tetragonal tungsten–bronze-type phase with appropriate annealing. Optical studies indicated that the films were highly transparent in the visible–near-infrared wavelength range and could support optical modes.

Microstructures of potassium hexatitanate (K2Ti6O13) whiskers prepared by calcination of KF and TiO2 mixture were studied through high-resolution electron microscopy. The rod axis of a K2Ti6O13 whisker is along the [010] direction. These whiskers normally have a lamellar structure in their longitudinal direction, and adjacent lamellae usually have the same crystallographic orientation. Each lamella might be further divided into several fine layers with a width on the nanometer scale in the same crystallographic orientation. The whisker can be split in the longitudinal direction along either the boundary between two lamellae or the weak binding crystal plane, such as (100) and (201) planes. The mechanisms for the formation of lamella and layer structures and for the splitting of whiskers are discussed.

Nanocrystalline nickel oxide–yttrium-stabilized zirconia (NiO/YSZ) composite powder for the solid oxide fuel cells was prepared by solution combustion through control of pH values and contents of glycine fuel in precursor solution. A strongly acidic precursor solution with appropriate amounts of glycine fuel added increased the specific surface area of the synthesized composite powders. This results from the increased binding of metal ions and glycine under strongly acidic solution (pH = 0.5) conditions. After sintering and reducing treatment of nanocrystalline NiO/YSZ composite, the Ni/YSZ pellet showed an ideal microstructure: fine Ni particles of 3 to 5 μm were distributed uniformly, and fine micropores around Ni metal particles were formed, thus leading to an increase in the triple phase boundary area among gas, Ni and YSZ.