Zn1–xMgxO is an important material for optoelectronic devices. We synthesized this material using a solution-based route. We investigated in detail the structural behavior of this material system using x-ray diffraction and Raman spectroscopy. Mg substitution up to x ≈ 0.10 does not change the crystal structure, as revealed by x-ray diffraction and Raman spectroscopic studies. This synthesis route is also suitable to prepare thin films by spin coating with the possibility of p and n doping.

TiO2 nanocrystals were prepared by a photo-assisted sol-gel process in which tetrabutoxide titanate was hydrolyzed in acidic medium under ultraviolet irradiation. X-ray diffraction and Raman spectra showed that the as-prepared TiO2 particles without further annealing were well-crystallized anatase. Such TiO2 particles were easily immobilized on dacron cloth and showed very high photocatalytic activity. In contrast, TiO2 particles were ill crystallized and showed lower activity when no light was introduced under otherwise equal conditions.

The solidification of Al–20 wt% Mn alloy was investigated under pressures up to 6 GPa. It was found that the solidification products under pressures below 4 Gpa were about the same, composed mainly of Al and Al6Mn. A new Al–Mn phase with needle like morphology and Al nanocrystallites in size less than 20 nm were obtained in the quenched alloy at 6 GPa. Structure analysis by transmission electron microscopy and x-ray diffraction indicated that the new phase had a C-center othorhombic unit cell with lattice constants of a = 0.7565(4) nm, b = 1.2965(6) nm, and c = 0.7801(6) nm. The composition was determined to be Al77.5Mn22.5 by election probe microanalysis. The phase evolution during solidification under different pressures was discussed. Our experimental results show that the pressure, as a basic thermodynamic variable like temperature, may play an important role on the solidification of the alloy.

Continuous epitaxial films of cuprous oxide (Cu2O) have been formed by the thermal oxidation of 1.5-μm-thick Cu metal films deposited on MgO(110) substrates. These films melted at 1118 °C in air, in agreement with equilibrium phase diagrams. Upon cooling from the liquid, a highly crystalline, epitaxial, 2.5-μm-thick Cu2O film was formed. X-ray diffraction spectroscopy revealed that the Cu2O film crystal structure was orthorhombically distorted from the bulk cubic crystal structure. High-resolution transmission electron microscopy showed that the film is coherent, and energy dispersive x-ray spectroscopy showed that interdiffusion is limited to the interface. These results suggest that a new epitaxially stabilized phase of Cu2O has been formed.

Pt electrodes with a 6–8-μm thickness were produced on alumina substrates by a double-print Pt screen-printing process that included a sequential heat treatment at 600 °C and 1300 °C. This process improved the final sintered double-print film because the first printed layer acted as a sintering template for the second printed layer. The sintered Pt films have a 95% coverage of the alumina surface, 92% density, 0.73-μm average surface roughness, and 16.10−5 Ω cm resistivity. The sintering behavior of Pt films exhibited three stages of densification: Stage I (T °C < 700 °C), exhibiting neck growth, and Stage II (700 < T °C < 1300 °C), exhibiting grain growth, have activation energies of 64 kJ/mol and 125 kJ/mol, respectively. Stage III exhibits a decrease in shrinkage due to Pt coalescence and island formation. The transition temperature, 700 °C, between Stages I and II corresponds to an anomalous increase in surface roughness and resistivity. The thickness of Pt films was a critical parameter for achieving alumina surface coverage. Uniaxial pressing of dried Pt films increased densification and reduced the surface roughness of double-print Pt films.

The 90° macrodomains in tetragonal Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMNT) crystals take the shape of coarse and straight strips under optical microscopes and scanning electron acoustic microscopes. However, 71° or 109° domains in rhombohedral PMNT crystals are relatively poor in contrast and become clearer, coarser and straighter as their composition becomes closer to morphotropic phase boundaries, showing an evolution series of micro-to-macro domain transformation. Moreover, domain configurations are also dependent on the nucleation and growth rate of domains, the crystal defects, and the cooling rate through Curie temperature. The appearance of macrodomains arises from the strengthening of depolarization field and the weakening of random field.

A nanostructured 5083 Al–Mg alloy powder was subjected to various thermal heat treatments in an attempt to understand the fundamental mechanisms of recovery, recrystallization and grain growth as they apply to nanostructured materials. A low-temperature stress relaxation process associated with reordering of the grain boundaries was found to occur at 158 °C. A bimodal restructuring of the grains occurred at 307 °C for the unconstrained grains and 381 °C for the constrained grains. An approximate activation energy of 5.6 kJ/mol was found for the metastable nanostructured grains, while an approximate activation energy of 142 kJ/mol was found above the restructuring temperature.

TiB2 thin films demonstrate considerable potential for use as protective overcoats in the magnetic recording industry due to their excellent mechanical and tribological properties and good chemical and thermal stability. In the many studies performed on TiB2 films, the relative effectiveness of ultrathin TiB2 films has not been systematically investigated for very thin TiB2 films. In the present investigation, film stress and microstructure in as-sputtered and annealed ultrathin TiB2 films were investigated as a function of thickness. Ultrathin TiB2 films, as thin as 5 nm, were observed to adequately protect an underlying magnetic layer from oxidation up to 400 °C.

An infiltration and growth process has been developed to produce single-domain Yba2Cu3Oy(123) as thick films on various substrates or as self-supporting fabrics. Commercially available Y2O3 cloths of square woven or satin woven structure were infiltrated with liquid phases from a suitable source containing barium cuprates and copper oxides and subsequently converted into Y2BaCuO5(211) and −123 phases by a series of distinct peritectic reactions. Depending on the final form of 123, the Y2O3 cloth was either clamped firmly at corners to produce a self-supporting 123 fabric or placed on a suitable substrate to result in a thick film coating of 123. The source material for the liquid phase being in the form of solid blocks was placed at corners of the cloth in the case of free-standing 123 fabrics. In case of the thick film configuration the liquid phase powder was spread on the surface of the Y2O3 cloth. A small c-axis-oriented MgO or Nd(123) seed was used to generate an oriented 123 domain in the infiltrated fabric. The solidification process was optimized to transform the entire Y2O3 fabric into a single-domain 123. The microstructure of the single domain was optimized in terms of 211 size and content for high Jc. A detailed description of the process, the growth mechanism, the resulting microstructures was given, and basic superconducting properties of the new form of 123 are briefly discussed.

Combinatorial libraries of the mixed oxide system Cu1−xCexO3 (0 ≤ x ≤ 1) have been generated using a modified Pechini powder synthesis process in conjunction with inkjet deposition. Mixed oxide crystalline powders were formed at temperatures below 500 °C. These powders have particle sizes in the range of 20.0 to 85.5 nm, and the powder surface area increases with cerium content. In addition, each of the mixed oxides (0 < x < 1) displayed catalytic activity in the CO oxidation reaction at temperatures between 150 and 350 °C. This novel protocol has also been used to generate a library of oxide powders of the perovskite-like La1−xSrxCoO3?δ system. The La–Sr–Co–O system from this protocol exhibits lower average surface areas than the Cu–Ce–O system (approximately 11.2 m2/g) due to higher decomposition temperatures but still acts as an active catalyst for the CO oxidation reaction.

The optical absorption spectra of AgInS2:Co2+ single crystals grown by chemical transport reaction using iodine as a transporting medium have been studied at 6 K. The peaks can be explained by the transitions of Co2+ in the Td symmetry with the spin-orbit coupling, which means that the deviations of the atomic sites from those of the ideal wurtzite structure can be considered negligibly small. The consideration of both the crystal field parameters and the electronegativity difference between atoms may indicate that Co atoms substitute In atoms.

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.

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.

A procedure using nanoindentation with spherical tipped indenters is presented that allows separation of elastic, anelastic, and plastic contributions to the deformation of thin films. The procedure was demonstrated on a range of lanthanum-modified lead titanate (Pb,La)TiO3 (PTL) ferroelectric thin films. Indentation stiffness coefficients ranging from 110 to 147 GPa have been obtained depending on the microstructure and orientation of the PTL films. This coefficient was equivalent to (and so, can be directly compared with) Young's modulus of a nontextured, unpoled ceramic when films do not present preferred orientation. The trends of the anelastic contribution with the thickness, structure, microstructure, and stress level at the film/substrate interface of the films were consistent with it being produced by ferroelastic domain wall movement. Pore compaction was a major mechanism of plastic deformation for the PTL films. Grain size also affected plastic deformation, probably as a consequence of its correlation with intergranular porosity. The technique has a high spatial resolution (contact area < 10 μm2 for the results presented here), which allowed the mechanical homogeneity of the films to be studied and inhomogeneities to be identified from their mechanical response (elastic, anelastic, and plastic).

F2 excimer laser (157 nm) irradiation was applied to modify sol–gel-derived amorphous Al2O3 thin films at ambient temperature. The surface morphology and density of the film were significantly altered by the laser irradiation (power: 2 mW/cm2/pulse). The surface properties of the film were also changed from hydrophilic to hydrophobic. These alterations were not observed when using ArF excimer laser (193 nm) irradiation at the same laser power as that of the F2 laser. It was found that the changes induced by F2 laser irradiation mainly arose from the direct photoexcitation of C = O groups in ethylacetoacetate, which was added as a chelating agent of aluminum-alkoxides. Consequently, photochemical reactions of the Norrish-type occur, resulting in the formation of hydrocarbon or olefin and the elimination of carbon monoxide (CO) or decomposition products. The elimination of CO is considered to cause the marked change in structure and surface properties of the film. Patterning of the gel films was successfully performed by using these findings.

Nanocrystalline nickel films of about 0.1 μm thickness grown by sputtering with and without substrate bias possessed average grain sizes of 9–25 nm. Variation in substrate bias at room and liquid nitrogen temperature of deposition strongly affected grain structure and size distribution. Qualitative studies of film surfaces showed variation in roughness and porosity level with substrate bias and film thickness (maximum of 8 μm). The films had tensile residual stress, which varied with deposition conditions. The hardness values were much higher than those of coarse-grained nickel but decreased with an increase in the film thickness because of grain growth.

Low-density, open-cell nickel base superalloy foams have been synthesized by a high-rate, electron beam-directed vapor deposition process and their mechanical properties evaluated. The deposition process uses an open-cell polymer foam template upon which is deposited a metal alloy coating. The electron beam evaporated flux was entrained in a rarefied transonic gas jet and propagated along the flow stream lines through the polymer structure. After vapor deposition, the polymer template was removed by low-temperature thermal decomposition. The resultant ultralightweight metal foams consisted of a three-dimensional open cell, reticulated structure possessing hollow triangular ligaments with relative densities of <3%. Their mechanical integrity was increased by either pressureless or transient liquid phase sintering. The mechanical properties of these ultralightweight metal foams were comparable to theoretical predictions for open-cell, reticulated foams.

To clarify some discrepancies in the literature about the formation of icosahedral quasi-crystal (IQC) in Al–Cu–Fe alloys, microstructures, and constituent phases of Al62.5Cu25Fe12.5 and Al65Cu20Fe15 alloys were studied. Each dendritic arm of the primarily solidified λ–Al13Fe4 phase is a single crystal that possesses no definite orientation relationship with the IQC, formed by peritectic reaction (L + λ + β → IQC) or a solid-state reaction (Cu-rich phases + λ + β →?IQC). This fact disproves an assumption that λ-phase is an approximant of the IQC. Two types of cubic phase, β-phase with CsCl structure containing more Fe and τ3 phase, which is a superstructure and contains less Fe, were observed depending on the composition and thermal history of the samples.

A nanocomposite structure was induced in gel of composition 60CuO · 40SiO2 (mol%) by first of all precipitating nano-sized copper particles by a reduction treatment and subsequently subjecting these to a controlled oxidation treatment. The particle size was of the order of 6.8 nm. Alternating current (ac) conductivity measurements were carried out on different specimens in the temperature range 300 to 630 K covering a frequency spectrum 0.1 kHz to 2 MHz. The ac conductivity was found to have a variation with frequency given by ωs, ω being the angular frequency and s the frequency exponent. The analysis of the variation of s as a function of temperature led to the conclusion that an overlapping large polaron tunneling mechanism was operative in this system. The effective barrier height for polaron transfer for infinite intersite separation was found to be almost twice in the case of the precursor gel as compared to that for the composite with the interfacial amorphous phase.

Typical microelectromechanical systems (MEMS) devices and packages are composed of micron-scaled structures. Experimental investigations on the effect of size on the deformation behavior of simple structures have shown that the deformation behavior of metals and polymers is size dependent. The size dependence in small structures is attributed to the contribution of nonnegligible strain gradients. In this work, torsion and bending of micron-sized rods and plates were analyzed by using a two-parameter model of strain-gradient plasticity. Microrod torsion and microplate bending experimental data were analyzed to determine the magnitude of the strain-gradient material parameters. The parametric analyses showed that conventional analysis is applicable only when the size of the structure is significantly larger than the material parameters, which are typically in the micron range. Strain-gradient analysis of micron-sized rod revealed that the presence of strain gradient increased the torque by three to nine times at the same twist. For MEMS structures with micron-sized features, conventional structural analysis without strain gradient is potentially inadequate, and strain-gradient analysis must be conducted to determine the elastoplastic behavior in the micron scale.