Optical studies of conformal GaAs layers grown on silicon substrates were carried out by cathodoluminescence, photoluminescence imaging, and micro-Raman spectroscopy. These techniques revealed, in the conformal GaAs layers, local variations of the luminescence intensity with the shape of stripes both parallel and perpendicular to the GaAs seed, associated with local variations of tensile stress. The cathodoluminescence and micro-Raman spectra suggest that this distribution of tensile stress plays an important role in the formation of mid-gap states responsible for the variations of the luminescence intensity. The high luminescence emission of the conformal GaAs layers compared to the emission of the GaAs seed grown directly on the Si substrate is consistent with the high quality of the conformal layers.

The development and evolution of texture in a Mg–10.6%wt Zr deposit obtained by physical vapor deposition was studied. The deposit exhibits a microstructure characterized by elongated grains with the [0001] direction parallel to the deposit growth direction. The volume fraction of the basal plane component increases throughout the thickness from 45% at the collector side up to around 70%. The minimization of interfacial energy of (0001) planes induces the initial texture at the earliest stage of the deposit formation. Furthermore, the increase in the volume fraction of the (0001) component during deposit growth is provoked by texture competition, which results in the development of grains with the [0001] direction parallel to the deposit growth direction.

Time-resolved x-ray diffraction measurements were carried out during and after the exposure of anhydrous boron oxide glass films to humid air. B(OH)3 crystals grew on the glass substrate with planar sheets of B(OH)3 molecules aligned parallel to the surface. After the space above the sample was evacuated, the crystal peaks began to disappear. During the decay, new crystals of orthoboric acid grew with the orientation of the B(OH)3 sheets perpendicular to the substrate. Then crystals with all orientations decayed completely, and an amorphous scattering pattern remained. The water acquired by the sample during the exposure eventually reacted with the anhydrous B2O3 glass to produce amorphous BO(3+y)/2Hy. The decay of the crystals took from one to several days, depending on the length of the exposure to humid air. Measurements of the metastable equilibrium phases in the B2O3–H2O binary system showed that at room temperature the amorphous phase could reach the composition BO1.85H0.7. At higher water concentrations this saturated amorphous phase coexisted with crystalline B(OH)3. This result is consistent with the instability of the crystalline B(OH)3 film in contact with anhydrous glass, and we present a thermodynamic model for this process. In the present case, amorphization is driven by the outdiffusion of water from a crystalline phase rather than interdiffusion in conventional solid-state amorphization.

Biaxially textured <100>-oriented SrTiO3 films were solution deposited on <100> LaAlO3 single crystals and <100>-oriented polycrystalline Ni tapes. Solution variables including varying titanium alkoxide chain length, inclusion of chelating agents, and inclusion of donor dopant, were investigated for their effect on film orientation, morphology, and oxygen diffusivity. The best <100> SrTiO3 orientation on high lattice mismatch (11%) Ni substrates was achieved through use of a discontinuous nucleation seed layer, which provided nucleation sites for subsequent continuous SrTiO3 films. Increased titanium alkoxide chain lengths appeared to suppress titanium hydrolysis reactions and improve film orientation. 13C nuclear magnetic resonance showed that significant quantities of water were generated due to esterification reactions, which appeared to cause hydrolysis and subsequent orientation degradation in the absence of chelating agents such as acetylacetone.

Increased ionic conductivity at nanoscale planar interfaces of the CaF2|BaF2 system was successfully modeled using molecular dynamics simulations. A criterion was established to construct simulation cells containing any arbitrarily lattice-mismatched interfaces while permitting periodic boundary condition. The relative (to the bulk) ionic conductivity increase at the 111 (CaF2)|111 (BaF2) interface was qualitatively reproduced. Higher conductivity, by a factor of 7.6, was predicted for the 001 (CaF2)|001 (BaF2) interface. A crystalline nanocomposite of the CaF2|BaF2 system, in which the [001] morphology is encouraged and crystallite dimensions are approximately 4 nm, was proposed to give ionic conductivity approaching that predicted for the 001 (CaF2)|001 (BaF2) interface.

PbMg1/3Nb2/3O3 (PMN) powder was prepared by citrate organic solution, and barium titanate (BT) seed particles were added to encourage the perovskite phase formation. Sintering was followed using the constant heating rate mode of a dilatometer, and it was observed that the seed concentration affected the PMN shrinkage rate and crystal structure. The study of the lattice parameters of the samples after the sintering process indicates that the diffusion of the titanium and of the barium inside perovskite and pyrochlore PMN phases occurs. Moreover, this substitution provoked a decrease of the lattice parameters as showed by the Rietveld refinement.

The morphological and phase composition changes during sintering of ultralight pure Al2O3 and Al2O3/TiO2 foams were investigated in the temperature range of 900–1600 °C in air. The titania (10 wt%) was incorporated during a nonhydrolytic foaming procedure to facilitate its uniform dispersion in the alumina matrix. The changes of linear shrinkage and related changes in effective density and porosity demonstrate a higher reactivity in the Al2O3/TiO2 foam. The formation of tialite phase in the Al2O3/TiO2 foams occurred below 1300 °C and remained stable during cooling under 1200 °C without stabilizers.

Germanium- and carbon-based films were deposited by plasma-enhanced chemical vapor deposition from tetramethylgermane (TMGe) with additions of oxygen, hydrogen, or argon. The index of refraction, extinction coefficient, and optical gap and Fourier transform infrared spectra of the films were measured as well as their stability in regular ambiance. It was found that the films deposited from pure TMGe were stable in time only if deposited at a negative bias above −250 V direct current. Films deposited at a bias of −150 V direct current could be stabilized by significant additions of oxygen to the plasma and complete stabilization was achieved at O2/TMGe ratios larger than 3 in the gas feed when GeOx films containing small amounts of C and H were obtained. Additions of hydrogen or argon to TMGe had only slight effects in improving the stability off the films.

With polypropylene as a prototype viscoelastic material at room temperature, it was found that a “nose” may appear in the unloading segment of the load–displacement curve during nanoindentation when the holding time at peak load is short and/or the unloading rate is small, and when the peak load is high enough. The load at which the nose appears was also found to decrease linearly with decreasing unloading rate. A linear viscoelasticity analysis was performed to interpret this effect. The analysis predicts a linear variation between the nose load and the unloading rate, and the slope of such a linear variation is also shown to be proportional to the viscosity parameter of the material. Thus, by measuring the slope of the nose-load versus unloading rate plot at a given temperature, the viscosity parameter of the specimen can be found. This is a new way of measuring the viscosity parameter of a material in addition to the existing method of force modulation and noting the frequency response of the displacement.

Sol-gel-derived metal oxide ceramic thin films deposited onto amorphous iron-rich substrates were found to form self-organized nanoporous structures dependent upon the extent to which the substrate is de-alloyed, a function of the substrate alloycomposition, acid concentration of the sol, and film drying conditions. Field emission scanning electron microscopy, transmission electron microscopy, and x-ray energy dispersive analysis were used to investigate details of the porous structure formation.Our studies showed the more electrochemically active elements in the amorphous substrate are de-alloyed by the sol in high-humidity environments, whereupon the liberated elements form oxides replicating the de-alloyed substrate matrix resulting in athree dimensional porous network structure.

Bi2Sr2Ca2Cu3O10+x and (Bi,Pb)2Sr2Ca2Cu3O10+x single crystals with a sharp superconducting transition at Tc = 109 K were grown using a modified KCl flux technique. The crystals show platelike morphology with typical dimensions of 0.5 × 0.5 × 0.002 mm3 and 0.25 × 0.25 × 0.001 mm3 for Pb-free and Pb-doped compositions, respectively. The formation of Bi-2212 intergrowth in the crystals is suppressed by utilization of a stable MgO crucible, suppression of the KCl evaporation, and isothermal heat treatment at a temperature close to the melting temperature of the oxide precursor in the flux. Morphology, phase purity, and chemical composition of grown crystals were determined by various analysis methods while the superconducting properties were studied by magnetization and resistivity measurements.

SiC/ZTM (zirconia-toughened mullite) nanocomposites were prepared by hot pressing mixtures of mullite gel, 2Y-TZP, and SiC nanopowders. The intimate mixing of Al2O3 and SiO2 components in the starting powder prevented intermediate ZrSiO4 phase formation during sintering. Addition of nano-sized SiC significantly retarded the matrix grain growth, making the microstructure much finer and more uniform. Transmission electron microscopy and high-resolution transmission electron microscopy revealed that many SiC nanoparticles were found in mullite and ZrO2 grains, and low-energy grain boundaries and mullite–liquid interfaces parallel to the {110} planes of rodlike mullite grains were formed. It is deduced that the formation of rodlike mullite grains is the result of the preferential development of these low-energy grain boundaries and mullite–liquid interfaces. The mechanical properties of the SiC/ZTM nanocomposite showed significant improvement over those of ZTM, and further enhancement in the mechanical properties was achieved by combinative strengthening with nano- and micro-sized SiC.

The LaNiO3 (LNO) thin films were deposited on Si substrate by rf magnetron sputtering. The interface and electrical properties of LNO/Si contacts were investigated. For the deposition at room temperature, an amorphous LNO film with a clean interface was formed on the Si. However, a thin silicon oxide layer of approximately 2.5 nm was formed at the interface between LNO and Si after rapid thermal annealing (RTA) at temperatures ≥450 °C. On the other hand, a highly (100)-textured LNO film along with an interfacial oxide layer of approximately 6.0 nm was obtained for the deposition at 400–450 °C. Nevertheless, if an ion beam etching was applied prior to the high temperature deposition at 400–450 °C, a clean interface at the interface could be obtained for the LNO/Si contacts. Moreover, crystallites with (111) planes grown epitaxially along the (111) planes of Si were found in the LNO films. All the contacts had shown good current–voltage characteristics of a Schottky diode with a barrier height of 0.69–0.78 eV for the LNO/n-Si contacts and 0.60–0.67 eV for the LNO/p-Si contacts, and the barrier height increased with the thickening of interfacial oxide layer. From the measurement of capacitance (C) under reverse bias (Vr) of the contacts made with LNO deposited on the ion-etched Si substrates, a linear relation was observed in the plot of C−2 against Vr except a deviation of linearity in the low-bias part of the curve. This deviation is most likely due to the segregation and inward diffusion of La and Ni near the interface of LNO/Si contacts. Nevertheless, the barrier heights evaluated from an extrapolation of linear part of the plots are reasonably consistent with those obtained from the I–V measurement.

Cobalt ferrite (CoFe2O4) nanoparticles were successfully synthesized by polymer matrix templated synthesis. Synthetic ion-exchange resins were used as hosts for the coprecipitation of cobalt ferrite where the nanopores of the resin acted as the constrained environment. The weight fraction of the particles within the resin was roughly 16%. X-ray diffraction analysis indicated that cobalt ferrite crystallites were about 1–7 nm in diameter. Magnetic properties measured using an alternating gradient magnetometer showed the particles (prepared using initial salt solution ratio of Fe3+:Co2+ of 1.5:1.0) were superparamagnetic with magnetization M (of the particle-resin system) in the range of 3.0 to 4.4 emu/g at 10 kOe of applied field. The least upper bound of the magnetic size was about 3 nm in diameter. Ratios of Fe3+ to Co2+ within the matrix of the resin before and after precipitation were investigated by x-ray fluorescence spectrometry and were found to be sensitive to the initial salt solution mixture. The ratio Fe3+:Co2+ of 1.5:1.0 was found to be a better mixture in terms of magnetization value. Spherical shape cobalt ferrite particles 2–8 nm in diameter were observed using transmission electron microscopy. The close agreement between the physical and crystallite size indicated that the particles are largely monocrystals.

Long beltlike nanowires were successfully synthesized for a semiconducting oxide of vanadium by a hydrothermal route at 180 °C for 5 h and were characterized by x-ray powder diffraction, energy dispersive -ray spectroscopy, and electron diffraction microscopy. The product is mainly layered V2O5 · 0.3H2O with a small fraction of V2O5 · xH2O (0.3 < x < 1.7) and V2O5 phases. The obtained nanowires, several tens of micrometers long and a few of tens of nanometers wide, are crystallized well, growing along the [010] direction. The effects of preparation conditions on the formation of the nanowires are discussed.

Heteroepitaxial KTaO3 thin films were synthesized by the hydrothermal method below 175 °C in highly alkaline aqueous KOH solutions. KTaO3 films synthesized in 7 M KOH solutions contained a defect pyrochlore phase that had (400) and (111) out-of-plane orientations. The (400) oriented pyrochlore islands were epitaxially related to the (100) SrTiO3 substrate while the (111) oriented pyrochlore islands had four in-plane variants. Pyrochlore-free KTaO3 films could be synthesized in a 15 M KOH solution. Pyrochlore-free films were also grown at 7 M KOH by delaying the introduction of the (100) SrTiO3 substrate into the synthesis solution until the conditions favoring the formation of the pyrochlore phase had dissipated.

Single shear lap specimens were subjected to creep, isothermal aging, and thermomechanical fatigue (TMF). Scanning electron microscopy micrographs of previously polished specimens revealed changes in surface morphology. Orientation imaging microscopy was carried out on the same specimens to study the microstructural evolution and crystal orientation changes. As-fabricated joints consistently show a preferred crystal orientation with a few minority orientations with highly preferred misorientations. Alloy additions caused an increase in the number of statistically significant crystal orientations and misorientations. The solidification microstructure was unchanged due to room-temperature creep. Aging caused development and motion of well-defined subgrain boundaries and removal of most minority orientations. TMF causes heterogeneous refinement of the microstructure that accounts for the localized grain boundary sliding in regions of high strain concentration. This study implies that the lead-free solder joints are not polycrystals, but multicrystals, so that deformation is very heterogeneous and sensitive to strain and temperature history.

Glass-ceramics containing ferroelectric CsLiB6O10 crystals were prepared by heat treating Cs2O–Li2O–B2O3 glasses. Second harmonic generation (SHG) was observed from samples prepared by two-step heat treatment (nucleation and growth); however, the intensity was rather weak. On the other hand, one-step heat treatment by the addition of a small amount of TiO2 to the glass resulted in the glass-ceramics containing small single crystal-like CsLiB6O10 particles. The strongest SHG observed was comparable with that of Y-cut quartz. The preferred orientation of precipitated CsLiB6O10 crystals was attributed to the occurrence of SHG from the glass-ceramics.

Aluminum matrix composites reinforced with various contents and sizes of silicon carbide particles (SiCp) were fabricated by squeeze casting. A lower melting point AA A383 aluminum alloy (A383 Al) was squeezed into the higher melting point SiCp/pure aluminum (SiCp/pure Al) and SiCp/AA 6061 aluminum alloy (SiCp/6061 Al) preforms. The volume percents of the ceramic reinforcements were effectively lowered from traditional 50 to 8–25 vol% by the addition of pure Al and 6061 Al powders in the preforms. The SiC particles uniformly distributed within the matrices, and no pore was found in these composites. The growth of silicon precipitates in A383 Al alloys was limited by the addition of the aluminum alloy powders and SiC particles, and the tensile properties of the alloys were effectively enhanced by the refinement of the silicon precipitates. The tensile strengths and elongations of the SiCp/pure Al/A383 Al and SiCp/6061 Al/A383 Al composites were both better than those of the A383 Al alloy. The T6-treated 12-μm SiCp/6061 Al/A383 Al composite exhibited the highest tensile strength of 301 MPa.

In-plane 90° rotated biepitaxial Fe3O4 thin films have been successfully prepared onto MgO (110) substrates using a CeO2 seed layer and their microstructure, electric, and magnetic properties were investigated. From the x-ray φ-scan measurements, the in-plane epitaxial relations were determined as 〈110〉Fe3O4//〈110〉MgO and 〈001〉Fe3O4//〈001〉MgO for the no-seeded Fe3O4 layer, and 〈001〉Fe3O4//〈110〉MgO and 〈110〉Fe3O4//〈001〉MgO for the CeO2 (110) seeded Fe3O4 layer. The CeO2 seed layer was found to rotate the upper Fe3O4 lattice at 90° upon normal axis to the layer against the no-seeded Fe3O4. The transmission electron microscopy and electron diffraction analyses revealed that the transition region of the biepitaxial Fe3O4 boundary between CeO2-seeded and no-seeded portions consisted of columnarlike polycrystalline grains. The Fe 3O4 films exhibited single-crystallinelike electric and magnetic properties, however, substantial spin-dependent-tunneling magnetoresistance across the 90° grain boundary was not observed even in the antiparallel situation for each Fe3O4 portion.