Epitaxial films of rare-earth (RE) niobates, RE3NbO7 with pyrochlore structures, were grown on biaxially textured nickel–3 at.% tungsten (Ni–W) substrates using a chemical solution deposition process. A precursor solution of 0.3–0.50 M concentration of total cations was spin coated on to short samples of Ni–W substrates, and the films were crystallized at 1050–1100 °C in a gas mixture of Ar–4% H2 for 15 min. Detailed studies revealed that RE-niobates with ionic radius ratio RRE/RNb (R = ionic radius) from 1.23 to 1.40 (i.e., Sm, Eu, Gd, Ho, Y, and Yb) grow epitaxially with the pyrochlore structure. X-ray studies showed that the films of pyrochlore RE niobate films were highly textured with cube-on-cube epitaxy. Scanning electron and atomic force microscopy investigations of RE3NbO7 films revealed a fairly dense and smooth microstructure without cracks and porosity. The rare-earth niobate layers may be potentially used as buffer layers for YBa2Cu3O7−δ coated conductors.

Porous Al2O3/Al catalyst supports were fabricated using a mixture of Al(OH)3 and Al powders, followed by pressureless sintering at a temperature of 600 °C in vacuum. Different pressures were used to prepare green compacts. High compaction pressure led to a high surface area and good mechanical and electrical properties for the sintered specimens. However, when the Al content in the sintered specimen exceeded a definite value, high compaction pressure decreased the surface area abruptly. Scanning electron microscopy observations revealed that agglomeration in the starting mixture has a significant effect on the microstructure of the sintered specimens. High compaction pressure greatly eliminated the agglomerates and led to a uniform microstructure for the sintered specimens. However, when the Al content in the starting mixture was too high, Al particles in the compacts prepared by the high pressure were largely sintered due to the high compact density so that most of the pores were closed. The present study indicates that a suitable compaction pressure is critical to obtaining superior Al2O3/Al supports.

We have designed and fabricated a standardized specimen holder that allows the operation of a microelectromechanical system (MEMS) device inside a transmission electron microscope (TEM). The details of the design and fabrication processes of the holder are presented. The sample loading mechanism is simple and allows reliable electrical contact to eight signal lines on the device. Using a MEMS-based, nanojoule calorimeter, we performed rapid-heating experiments on Bi nanoparticles to demonstrate the functionality of the holder. We show that the heat capacity can be measured simultaneously with TEM observations. The size-dependent melting of Bi nanoparticles was observed simultaneously by nanocalorimetry and selected area diffraction measurements. We believe this approach will open up new experimental pathways to researchers, combining the speed and resolution of transmission electron microscopy with the flexibility, precision, and compactness of MEMS-based sensors and actuators.

Nanocomposite thin films consisting of Au nanoparticles embedded in yttria-stabilized zirconia (YSZ) were synthesized at room temperature by radio frequency magnetron co-sputtering from YSZ and Au targets and subsequently annealed in an argon atmosphere. Au microstructure and particle size were characterized as a function of annealing temperature from 600 to 1000 °C by x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Rutherford backscattering spectroscopy. Spectroscopic ellipsometry was also used to determine the optical constants of the resulting films. In particular, the refractive index of the nanocomposites was found to undergo an anomalous dispersion in the spectral region where the extinction coefficient achieves its maximum. Additionally, the incorporation of Au in the YSZ matrix was found to increase the refractive index in comparison to that of YSZ. At annealing temperatures higher than 800 °C, a good agreement was found between experimental findings and theoretical models using bulk dielectric functions for Au, as modified to account for a reduced mean free path for scattering than that for free electrons. However, for annealing temperatures below 800 °C, an additional offset was required for the optical constants of Au to obtain good agreement between theory and experiment. This behavior was attributed to a relatively high atomic Au concentration in the YSZ matrix.

The plane-strain bulge test is a powerful new technique for measuring the mechanical properties of thin films. In this technique, the stress–strain curve of a thin film is determined from the pressure-deflection behavior of a long rectangular membrane made of the film of interest. For a thin membrane in a state of plane strain, film stress and stain are distributed uniformly across the membrane width, and simple analytical formulae for stress and strain can be established. This makes the plane-strain bulge test ideal for studying the mechanical behavior of thin films in both the elastic and plastic regimes. Finite element analysis confirms that the plane-strain condition holds for rectangular membranes with aspect ratios greater than 4 and that the simple formulae are highly accurate for materials with strain-hardening exponents ranging from 0 to 0.5. The residual stress in the film mainly affects the elastic deflection of the membrane and changes the initial point of yield in the plane-strain stress–strain curve, but has little or no effect on further plastic deformation. The effect of the residual stress can be eliminated by converting the plane-strain curve into the equivalent uniaxial stress–strain relationship using effective stress and strain. As an example, the technique was applied to an electroplated Cu film. Si micromachining was used to fabricate freestanding Cu membranes. Typical experimental results for the Cu film are presented. The data analysis is in good agreement with finite element calculations.

Using Blech’s structure, we studied the electromigration (EM) behaviors of four different Sn(Cu) and Sn(Ni) alloys, which are Sn, Sn0.7Cu, Sn3.0Cu, and Sn1Ni. The order of the EM rates was determined to be Sn0.7Cu > Sn > Sn3Cu > Sn1Ni. We believe that the lower yielding strength and higher grain boundary density of Sn0.7Cu were the main reasons that Sn0.7Cu had the fastest EM rate. Moreover, we found that the addition at Ni could effectively retard EM. The critical products of Sn, Sn0.7Cu, and Sn3.0Cu, which were determined to be 1500, 500, and 1580 A/cm, respectively. The diffuse-effective charge (DZ*) values of the solder stripes from this present work have same order magnitude of the reported values, which were measured by using actual solder bumps.

Nitrogen-doped titanium oxides nanostructures were synthesized by a new method proposed here from titanium oxysulfate precursor in a NH4OH solution under hydrothermal conditions without any extra templates as structure driving agents. The material synthesized with NH4OH was an ammonium titanate and showed curled nanosheets, nanofibers or nanorods morphologies depending on the molar ratio of NH4OH to titanium precursor and the hydrothermal temperature. The nanofibrous titanates had a high surface area over 500 m2 g−1 and a pore volume of 0.72 cm3 g−1. The calcination of as-synthesized material at 673 K produced a titanium oxynitride TiO2−xNx with anatase phase, which absorbed visible light. Ion exchange of ammonium ion of the titanate with sodium Na2Ti3O7−xNx enhanced the thermal stability of the titanate phase.

In a previously developed method for estimating Young’s modulus E by depth-sensing indentation with spherical-tipped Berkovich indenter, the E value is deduced from several functional relationships (established by finite element analysis) relating nominal hardness/reduced elastic modulus ratio (Hn/Er) and elastic work/total work ratio (We/W). These relationships are specified for different absolute bluntness/maximum displacement ratios (Δh/hm). This paper reports the generalization of the method by proposing a function to replace all the above mentioned Hn/Er−We/W relationships. The function contains only a parameter Vr ≡ Videal/Vblunt instead of Δh/hm, where Videal is defined as the indented volume bounded by the cross-sectional areas measured at the maximum displacement hm for an ideally sharp indenter, and Vblunt is that of the real indenter. The use of Vr to replace Δh/hm is for the purpose of extending the application of the method for non-spherical tipped Berkovich indenters. The effectiveness of the method for materials of prominent plasticity was demonstrated by performing tests on carbon steel and aluminum alloy using three Berkovich indenters with different tip shapes.

Anisotropic yield behavior of lotus-type porous iron fabricated using the continuous-zone-melting method in a pressurized nitrogen and hydrogen atmosphere has been investigated. The 0.2% offset strength (compressive yield stress) in the loading direction parallel to the longitudinal axis of pores decreases linearly with increasing porosity, while the perpendicular strength decreases steeply. The strength versus porosity curves can be expressed using a well-known power law formula. In addition, the 0.2% offset strength of lotus iron prepared in a nitrogen and hydrogen atmosphere is found to be larger than that of lotus iron prepared in a hydrogen and helium atmosphere, which is attributed to the solid solution hardening by the solute nitrogen. Furthermore, we compare the experimental results to calculations obtained by means of the extended Qiu-Weng’s mean-field method, and the comparison suggests that local stresses deviated from the average stress are dominant in the macroscopic yield behavior of lotus metals.

Chemical solution deposition (CSD) is used to grow high-quality (100)-oriented films of SrTiO3 (STO) on CSD Ba0.2 Ca0.8TiO3(100) (BCT) templates on textured W-doped Ni(100) (Ni:W) tape substrates. The BCT template films form a thin layer or “skin” that bridges its significant porosity. STO films grown at 1000 °C appear optimized for heteroepitaxial orientation, surface coverage, and film smoothness. Both interfaces in the STO(100)/BCT(100)/Ni:W(100) stack demonstrate excellent atomic registry and compositional abruptness. Doping STO with a few atomic percent of Nb reduces oxygen diffusion into the film by an order of magnitude and provides greater protection to the Ni interfacial surface from oxidation during the growth of additional functional oxides requiring relatively higher p(O2) high-temperature processing, such as superconducting YBa2Cu3O7−δ. CSD growth of BCT and STO also planarizes pre-existing grooves in the Ni:W(100) tapes while maintaining a high degree of orientation by forming facets at the interfaces.

Five different mixed-perovskite (AA′)(BB′)O3 single crystals were grown, where A = La, Nd; A′ = Sr; B = Al, Ga; and B′ = Ta, Nb. The as-grown crystals were yellowish/brownish. After annealing in air, the coloration was more intense. Annealing in a reducing atmosphere decreased coloration. The crystals were investigated by transmission spectroscopy, electron spectroscopy for chemical analysis (ESCA), and single-crystal x-ray diffraction. Additional broad absorption bands in the transmission spectra were observed for the as-grown samples. They are in line with the changes of the shape of O(1s) ESCA peaks. Redundant interstitial oxygen ions were recognized as the reason for the crystal coloration. All structures were solved and refined in different space groups of the regular system. Some of the unit cells have a doubled lattice constant: (i) lanthanum strontium gallium niobate, Pm3m, 3.9323(5) Å, at 100 K, 3.9270(5) Å; (ii) neodymium strontium aluminum tantalate, Pm3m, 3.8353(4) Å; (iii) lanthanum strontium aluminum tantalate, Pn3m, 7.720(1) Å, annealed in reducing atmosphere, 7.708(1) Å; (iv) neodymium strontium aluminum niobate, Fm3m, 7.744(4) Å.

Highly oriented copper nanowires were electrochemically synthesized in a porous alumina membrane template using a new type of weak-acid electrolyte. The Cu nanowires that were deposited have (110) preferred orientation, which is different from most electrochemically deposited Cu nanowires, and they can grow homogeneously. Transmission electron microscopy was used to investigate the room-temperature oxidation behavior, and it was observed that sample treatment methods greatly influence the oxidation rate of the wires. Cu nanowires with different diameters have different resistance to oxidation. The orientation relationship between oxide layer and small-diameter Cu nanowire was determined to be (001) Cu2O // (111) Cu, (110) Cu2O // (110) Cu, and [110] Cu2O // [112] Cu. The possible oxidation process is also discussed.

Softening or melting behavior of the organically-modified siloxane hybrid gels and glasses in the system of RSiO3/2 and R2SiO2/2 (R: methyl and phenyl) has been investigated to obtain a new family of low-melting glasses. The RSiO3/2 and RSiO3/2–R2SiO2/2 gels showed softening temperatures around 50–100 °C. The softening temperature of RSiO3/2 single-component glasses, which were obtained by melting the corresponding gels at a temperature above the softening temperature, increased by heat-treatment at 200 °C, and finally showed no softening behavior. On the other hand, in the PhSiO3/2–Ph2SiO2/2 binary glasses, the softening temperatures showed a tendency to saturate after longer heat treatment over 200 h. These facts indicate that the present organically modified siloxane system will be a potential candidate for the low-melting glass.

Hybrid organic–inorganic nanoporous thin-film glasses are extremely fragile and prone to stress-corrosion cracking in reactive environments. This has limited their integration as ultra low dielectric constant layers in high density integrated circuits. We demonstrate how crack growth is influenced by non-buffered aqueous solutions and show that with increasing pH, crack-growth rates are significantly accelerated. Interestingly, a crack growth regime limited by the transport of hydroxide ions to the crack tip was observed. Existing models commonly used to predict crack growth are shown to over estimate the experimental data by 6 orders of magnitude. We rationalize this behavior in terms of a significant difference in the crack tip solution chemistry as compared to that of the bulk and propose both chemical reaction and transport mechanisms to support this hypothesis.

Phase-pure Ba2Ti9O20 powders were made by doping 3 wt% of V2O5 to a Ba:Ti = 2:9 molar composition, and the effects of the dopant on the phase formation were investigated. The study shows that BaTiO3, BaTi2O5, and BaTi4O9 were the intermediate phases before the formation of Ba2Ti9O20 for samples with or without V2O5. However, with V2O5 doping, the temperature at which Ba2Ti9O20 occurred were lowered from 1150 to 1050 °C and single phase Ba2Ti9O20 powders was easily obtained at 1150 °C for 2 h. Microstructure of the powders was examined by field emission scanning electron microscopy. No evidence of V2O5–Ba2Ti9O20 solid-solution was found by x-ray diffraction and energy-dispersive spectroscopy. The benefit of V2O5 to facilitate the Ba2Ti9O20 synthesis is most probably due to a vanadium-containing eutectic liquid phase which accelerates the migration of reactant species.

Transmission electron microscopy (TEM) and nanoindentation, both with in situ heating capability, and electrical resistivity measurements were used to investigate phase transformation phenomena and thermomechanical behavior of shape-memory titanium-nickel (TiNi) films. The mechanisms responsible for phase transformation in the nearly equiatomic TiNi films were revealed by heating and cooling the samples inside the TEM vacuum chamber. Insight into the deformation behavior of the TiNi films was obtained from the nanoindentation response at different temperatures. A transition from elastic-plastic to pseudoelastic deformation of the martensitic TiNi films was encountered during indentation and heating. In contrast to the traditional belief, the martensitic TiNi films exhibited a pseudoelastic behavior during nanoindentation within a specific temperature range. This unexpected behavior is interpreted in terms of the evolution of martensitic variants and changes in the mobility of the twinned structures in the martensitic TiNi films, observed with the TEM during in situ heating.

Nano- and micrometer size spherical bismuth particles were prepared by reducing bismuth salts in simple and mixed polyols at elevated temperatures. In general, the conversion to metallic bismuth was preceded by the formation, at intermediate temperatures, of bismuth-polyol compounds. By changing the type of bismuth salt, the composition of the polyol mixture, and the temperature of the process, these precursors were successfully converted into spherical bismuth particles. It was found that the reduction process proceeds only if the temperature of the polyol exceeds the values at which the intermediate bismuth-polyol are stable, which was determined to be around 220 °C.

Carbon-doped oxide SiCOH films with low to ultralow dielectric constants were prepared on a Si substrate by plasma-enhanced chemical vapor deposition (PECVD) from mixtures of SiCOH precursors with organic materials. The films have different levels of nanoscale porosity resulting in different dielectric constants and mechanical properties. The mechanical properties of the films have been characterized by continuous-stiffness nanoindentation measurements. To study the effect of film thickness, each group of samples with the same dielectric constant was composed of samples prepared with different film thicknesses. It is shown that the effective hardness and modulus of the SiCOH/Si substrate system depends significantly on indentation depth due to substrate constraint effects. The “true” film properties were determined using both an empirical formulation of the effective modulus and direct inversion based on a finite element model. The hardness and modulus of three groups of samples with different degrees of dielectric constants have been measured. The hardness increases from 0.7 to 2.7 GPa and modulus from 3.6 to 17.0 GPa as the dielectric constants change from 2.4 to 3.0. While for stiffer films the modulus measured at an indentation depth 10% of the film thickness is close to the “true” value for films thicker than 0.5 μm, the measured value can give an overestimate of up to 35% for softer films. Thin film cracking and film–substrate debonding have been observed with scanning electron and atomic force microscopy at the indentation sites in softer films. The damage initiation is indicated by pop-in events in the loading curve and sharp peaks in the normalized contact stiffness curves versus indentation depth.

Production of gold nanoparticles with the specific goal of particle size control has been investigated by systematic variation of chamber pressure and substrate temperature. Gold nanoparticles have been synthesized on SiO2 nanowires by plasma-enhanced chemical vapor deposition. Determination of particle size and particle size distribution was done using transmission electron microscopy. Average nanoparticle diameters were between 4 and 12 nm, with particle size increasing as substrate temperature increased from 573 to 873 K. A bimodal size distribution was observed at temperatures ≥723 K indicating Ostwald ripening dominated by surface diffusion. The activation energy for surface diffusion of gold on SiO2 was determined to be 10.4 kJ/mol. Particle sizes were found to go through a maximum with increases in chamber pressure. Competition between diffusion within the vapor and dissociation of the precursor caused the pressure effect.

Bulk metallic glasses with a maximum diameter of 2.5–5 mm were formed in Mg75Cu5Ni10Gd10, Mg70Cu15Ni5Gd10, and Mg65Cu20Ni5Gd10 systems by copper mold casting. There is a clear tendency for glass-forming ability (GFA) to increase with increasing solute content. These bulk glassy alloys exhibit a large supercooled liquid region (ΔTx) of 44–64 K, indicating high thermal stability of the supercooled liquid. The Young’s modulus, fracture strength, elastic elongation limit, and plastic strain are in the range of 54–59 GPa, 854–904 MPa, 1.50–1.55%, and 0.10–0.20%, respectively. The Mg65Cu20Ni5Gd10 alloy exhibited the highest values of Young’s modulus and strength, while the largest plastic strain was obtained for the Mg75Cu5Ni10Gd10 alloy. The bulk Mg–Cu–Ni–Gd-based metallic glasses exhibited distinct enhanced corrosion resistance compared to Mg65Cu25Gd10 glassy alloy in NaCl aqueous solutions. The fabrication of the Mg-based bulk glassy alloys exhibiting a high strength level of about 900 MPa and plastic strains of ∼0.2%, in conjunction with good corrosion resistance, indicates that the Mg-based bulk glassy alloys may be used as a new generation of structural material.