Growth of the REBa2Cu3Oy (REBCO, RE = Y, Nd) crystals on the MgO substrates by the liquid phase epitaxy (LPE) process was investigated to clarify the growth mechanism. The crystal orientation of in-plane alignment was improved during the LPE process due to the preferential dissolution and growth even from a polycrystalline seed film. The orientation of preferential growth depended on the kind of RE for the REBCO system. The phenomena could be explained by the coarsening model by introducing the difference in the interfacial energies, which were considered not only general lattice matching but the Coulomb force at the interface between the REBCO and the MgO crystals. The preferential growth model was developed, and the calculation results showed a good agreement with the experimental results.

Instrumented indentation testing (IIT) is a relatively new form of mechanical testing which significantly expands on the capabilities of traditional hardness testing. In an IIT experiment, an indenter of known mechanical properties is pressed into contact and then withdrawn from a test material. The fundamental measurements during an IIT experiment are the applied load and the resulting penetration of the indenter into the test surface. The Hertzian contact model, or a derivative thereof, is often employed to relate these measurements to interesting mechanical properties of the test material. This article argues for a small correction to the Hertzian contact model when applied to instrumented indentation data. The magnitude of the correction primarily depends on Poisson's ratio of the test material and the contact radius normalized by the radius of the indenter tip. Neglecting this correction can cause significant errors in the calculation of elastic modulus and hardness from instrumented indentation data.

Carbothermal reduction of kyanite, a natural aluminosilicate with high alumina content (Al2O3 · SiO2), was used as a way to synthesize SiC–Al2O3 powder. Carbon black was mixed with the mineral precursor in a molar ratio of (C/SiO2) = 5.5. The Carbothermal reaction sequence was studied in the temperature range 1260–1550 °C. Completion of the reaction at 1550 °C gave β–SiC-whiskers and α–Al2O3 particles as final products. From observations, the impurities contained in the mineral precursor behave as catalysts for the vapor–liquid–solid whisker growth mechanism. When the specific surface area of the starting carbon was increased from 330 to 996 m2/g, the carbothermal reaction rate increased but the morphology of the SiC-whiskers became very irregular. This study aimed to identify the main reaction conditions for obtaining a favorable morphology of the synthesized powder for elaborating Al2O3–SiC-whisker composite materials by using low cost starting materials and a relatively simple in situ synthesis route in comparison to the conventional way of separately preparing the phases SiC (whiskers) and Al2O3 before elaborating composites.

Non-steady-state solidification of YBa2Cu3O6+δ (Y-123) superconducting oxides was observed by the isothermal undercooling experiment. A sudden decrease in crystal growth rate was found for all the Y-123 samples processed at the different temperatures and from the different Y2BaCuO5 (Y-211) contents in the initial composition. Quantitative analysis revealed that the Y-211 particles are pushed by the Y-123 crystal and accumulate in the liquid during solidification. It is also found that the particle volume fraction increased and reached a constant value of about 0.6, when the growth rate decreased abruptly, regardless of a variety of growth conditions. A simple solidification model is developed to interpret the experimental observation. This model shows that particle accumulation, as a result of the particle-pushing behavior, causes less connectivity of the liquid and thereby decreases the liquid diffusion flux, which is responsible for the non-steady-state solidification of Y-123.

The joining characteristics of oxidized SiC particles with Al–Mg alloy during reaction infiltration processing for fabrication of the composite were studied. From the measurement of weight changes due to the transformation from SiC into SiO2, it became clear that the thickness of SiO2 layer which was formed at the surface of SiC particles increased parabolically with holding time at the given exposing temperatures. The degree of oxidation of the preform made by SiC particles can be controlled by the application of the present oxidation data. The microstructure observed by field emission scanning electron microscopy showed network skeleton via necklike oxidized-joining among the SiC particles and the compressive strength of the perform increased with oxidation temperature. Furthermore, the microstructure of the composite which was fabricated by Al–2 wt% Mg alloy via reaction infiltration processing was examined and the formation of spinel was observed to join the matrix with the particles like a bridge, which is suitable to make the complicate and strong preforms for the near net-shape composites application in electronic packaging.

The creep deformation in fine-grained polycrystalline Al2O3 is highly suppressed by the addition of 0.1 mol% LuO1.5. The transient creep behavior in Lu-doped Al2O3 was examined at the testing temperature of 1250–1350 °C, and the data were analyzed in terms of the effect of stress and temperature on the extent of transient time and strain. The experimental data on the transient creep in Lu-doped Al2O3 showed good agreement with the prediction from a time function of the transient and the steady-state creep associated with grain boundary sliding as well as an undoped one. The difference in the transient creep between Lu-doped and undoped Al2O3 can also be explained by the retardation of grain boundary diffusion due to the Lu3+ ions segregation in the grain boundaries.

A scanning thermal microscope (SThM) was used to measure the thermal conductivity of thin sputter-deposited films in the thickness range of 10 nm–10 μm. The SThM method is based on a heated tip that is scanned across the surface of a sample. The heat flowing into the sample is correlated to the local thermal conductivity of the sample. Issues like the contact force, the surface roughness of the sample, and tip degradation, which determine to a great extent the contact area between tip and surface, and thus the heat flow to the sample, are addressed in the paper. A calibration curve was measured from known reference materials to quantify the sample heat flow. This calibration was used to determine the effective thermal conductivity of samples. Further, the heat diffusion through a layered sample due to a surface heat source was analyzed with an analytical and numerical model. Measurements were performed with films of aluminum, ZnS–SiO2, and GeSbTe phase change material of variable thickness and sputter-deposited on substrates of glass, silicon, or polycarbonate. It is shown in the paper that the SThM is a suitable tool to visualize relative differences in thermal structure of nanometer resolution. Determination of the thermal conductivity of thin layers is possible for layers in the micrometer range. It is concluded that the SThM is not sensitive enough to measure accurately the thermal conductivity of thin films in the nanometer range. Suggestions for improvement of the SThM method are given.

The effect of microstructure on residual stress in diamond thin film was investigated. The diamond thin film was deposited by the hot filament chemical vapor deposition process with hydrogen/methane precursor gas and followed by annealing at 1150 °C for 1–30 min. The residual stresses of the diamond thin film were measured by Raman spectroscopy. A model to estimate the residual stress was proposed on the basis of grain boundary relaxation mechanism and microstructural analysis of diamond thin film. It is confirmed that the residual stress in diamond thin film is proportional to a microstructural factor, 1/ [D( f + 1)]1/2, where D is the grain size of diamond and f is the volume ratio of nondiamond carbon/diamond.

Nanoindentation is a simple and effective means for evaluating the mechanical properties of thin films. In such circumstances, nanoindentation testers have been developed and commercialized by some companies. In this study, we tested the standard four specimens using six different types of testers and established a method to evaluate the nanoindentation data. The method requires only two correction factors; one is the frame compliance, Cf, of the testers, and the other is the error of the detection of the original surface which includes both the truncation of the indenter apex and the damage of the surface caused by the preloading of the indenter. The latter correction is conducted by adding a correction length, ΔhC, to the measured penetration depth, h. It was found that the values ΔhC increase with decrease in the hardness of material and are very sensitive to the performance of the testers.

Combustion synthesis (CS) of NiAl-based materials reinforced by TiB2 particles was investigated under both terrestrial and microgravity conditions. The synthesized metal matrix composites (MMC) are characterized by very fine (<1 μm) reinforced particulates, which have strong bonding along their entire surface with matrix (NiAl) and are distributed uniformly in it. It was found that microgravity leads to a decrease in the average TiB2 particle size, while higher volume fraction of NiAl component in the material leads to the formation of coarser reinforced particulates. The mechanism of structure formation of different MMCs during CS was identified by using the quenching technique. For example, it was shown that TiB2 grains appear due to crystallization from the complex (Ni–Al–Ti–B) liquid solution formed in the combustion front. An overall decrease of microstructural transformation rates was observed under microgravity.

Nano-AgI arrays were synthesized by electrochemical double liquor deposition in ordered porous alumina membrane. On the basis of the analysis of x-ray diffraction patterns, the assembly of nano-AgI/Al2O3 is a mixture of a cubic zinc blende type γ–AgI and a hexagonal wurtzite type β–AgI. The visible–ultraviolet optical absorption measuring showed that the assembly only had an absorption edge at 2.82 eV and exhibited the optical features of a semiconductor with a direct band gap. The absorption edge of the assembly was shifted to a shorter wavelength compared with pure γ–AgI and a longer wavelength compared with pure β–AgI. We believed that the change of the absorption edge of the assembly is due to the mixture of γ–AgI and β–AgI.

Dielectric response of mesoporous silica films was monitored as a function of several gas-phase chemical species. The effects of humidity, ammonia, and methane on dielectric constant and dissipation factor of films subjected to different chemical treatments are described. Dielectric constant and dissipation factor of partially dehydroxylated films were found to be highly sensitive to both water vapor and ammonia in air. The capacitive devices based on mesoporous silica films show potential for use in chemical sensors.

Circular and hexagonal microholes, ranging in size from several nanometers to micrometers, were generated in a graphite surface by electron beam irradiation. The depth of the holes was always 0.34 nm, indicating that only the uppermost layer was modified. The shape of the holes was switched from circular to hexagonal when the size reached about 500 nm. Although the hexagons appeared at random on the surface, they were aligned in one direction, implying that the formation and growth of the holes were determined by the atomic structure of graphite. The results described in this study will be used to modify the surface structure of graphite for many applications.

The resistance change with applied stress was measured for ruthenium-based metal–insulator–metal thick films under tensile and hydrostatic pressures over the temperature range −25 to +135 °C. The derived longitudinal, transverse, and hydrostatic piezoresistivity coefficients were corrected for elastic effects to yield the corresponding piezoresistivity coefficients and their temperature dependencies. The results clearly demonstrate for the first time a hydrostatic piezoresistivity coefficient that is sevenfold larger than the longitudinal component. Symmetry analysis is used to explain this phenomenon and to deduce additional piezoresistivity matrix elements and their degeneracy. In addition, pressure effects on electrical transport support a tunneling mechanism.

A hydrothermal route was proposed to prepare and control nanocrystalline silver indium sulfides (orthorhombic AgInS2, tetragonal AgInS2, and cubic AgIn5S8). The reaction was carried out in an autoclave in the temperature range of 100–280 °C with AgCl, InCl3, and thiourea as reactants. X-ray powder diffraction patterns and transmission electron microscopy images showed that the products were AgInS2 and AgIn5S8 phases and well crystallized with grain diameter in the range of 20–70 nm. X-ray photoelectron spectra of the single AgIn5S8 phase revealed the surface stoichiometry (AgIn5.05S8.11), and its room temperature Raman spectrum showed a strong peak at 130 cm−1 and a weak peak at around 290 cm−1. The influence of reaction temperature on the phases in the final products was investigated. A possible reaction mechanism of the formation of silver indium sulfides was also briefly discussed.

Macroporous titania (TiO2) films were prepared by a sol-gel dip coating method from a system containing poly(ethylene glycol) (PEG) and poly(vinylpyrrolidone) (PVP). The thickness of the macroporous films increased with an increase in PVP concentration, but the excess incorporation of PVP suppressed the macroscopic phase separation and enhanced the formation of macroscopic cracks. The porosity and the domain size were simply determined by PEG concentration. Although both PEG and PVP are hydrogen-bonding polymers having proton-accepting ability, preparation of macroporous TiO2 films was unsuccessful in systems containing only PVP as a polymer. Macroporous TiO2 films having interconnected pore structure as thick as 1 mm were successfully prepared by repeating the deposition several times.

Depth-sensing indentation testing has proven extremely useful in the determination of mechanical properties of thin films and small volumes of material. However, the validity of the results obtained depend largely on the corrections made to the experimentally recorded data to account for initial penetration depth, nonuniformities in indenter shape, and compliance of the loading frame. The present work examines each of these issues and presents potential methods of correction for them. The present work also highlights limitations inherent in the data analysis methods and the significance of these in terms of experimental test parameters.

The statistical behavior of ceramic and metal laminates was studied, and in particular the relationship between the failure distribution of the laminate and that of the ceramic layers that it comprises. An important result of this investigation is the ability to predict the misfit stresses due to thermal processing of the laminates. A finite different scheme that was capable of calculating the local stresses at each constituent and of considering the thermal residual stresses was developed. The laminated system was constructed from 380-μm-thick alumina alternating with nickel foil 25- or 50-μm thick.

The analysis of metallothermic reduction as an electronically mediated reaction predicted that the particle size of solid product could be reduced if the reaction were conducted in a medium that is a mixed conductor (ionic and electronic). This prediction was confirmed by reacting TaCl5 with sodium, each dissolved in liquid ammonia, to produce tantalum powder having an average particle size over an order of magnitude finer than the micron-sized powders produced commercially today. Metallothermic reduction in a mixed conducting medium has been extended to a multicomponent system in order to synthesize nanosized powder of Nb3Al by co-reduction of NbCl5 and AlCl3 both dissolved in liquid ammonia.

The effect of compositions of host precursors on the afterglow and phosphorescent decay properties of Eu2+- and Dy3+-coactivated strontium aluminates (SAED) synthesized by a sol-gel process has been investigated. A variety of strontium aluminates such as Sr3Al2O6, SrAl2O4, and SrAl12O19 have been identified in the samples prepared from starting precursors with Al/Sr ratios ranging from 1 to 12, respectively. The initial afterglow intensity (I0) for SAED phases was found to vary with Al/Sr ratio of the sol-gel precursor, with a maximal I0 appearing in the sample with Al/Sr of 2 in which SrAl2O4 dominated. The afterglow decay rate was found to be fastest for sample with Al/Sr ratio of 1:1 in which Sr3Al2O6 phase dominated. Moreover, the afterglow decay rates for those with Al/Sr ratio of 2:1 to 12:1, in which SrAl2O4 and SrAl12O19 dominated, were found to be slow and similar.