An increasing number of technologies benefit from or require patterned surfaces on a micro- and nanoscale. Methods developed to structure polymer films can be adapted to fabricate low-cost patterned ceramics using nonlithographic techniques, for example, dewetting and phase separation in thin films. In this paper we describe a simple patterning process that does not require a template and is able to produce Fe2O3 microdots with a spatial periodicity. Our method involves the dewetting of a silicon substrate by a thin metal oxide precursor film, in which the liquid film breaks up because of fluctuations in the film thickness induced by solvent evaporation or an external applied electric field. The patterning is followed by a thermal treatment at 550 °C to produce crystalline Fe2O3 microdots with a diameter range of 200 nm to 3 μm.

Self-assembled monolayers (SAMs) were formed on gold at anodic potentials from solutions containing two different alkyl thiosulfates, CH3(CH2)10S2O3Na and HO2C(CH2)10S2O3Na. The resulting two-component SAMs were analyzed using x-ray photoelectron spectroscopy to relate their compositions to those of the solutions from which they were adsorbed. This relationship was more linear than reported for analogous SAMs adsorbed from mixed solutions of alkanethiols. The wettability of these surfaces by water and by hexadecane was also measured and compared to analogous SAMs prepared by chemisorption of thiols from solution.

SiGe alloys belong to the class of classic high temperature thermoelectric materials. By the means of nanostructuring, the performance of this well-known material can be further enhanced. Additional grain boundaries and point defects added to the alloy structure result in a strong decrease in thermal conductivity because of reduced lattice contribution to the overall thermal conductivity. Hence, the figure of merit can be increased. To obtain a nanostructured bulk material, a nanosized raw material is essential. In this work, a new approach toward nanostructured SiGe alloys is presented where alloyed nanoparticles are synthesized from a homogeneous mixture of the respective precursors in a microwave plasma reactor. As-prepared nanoparticles are compacted to a dense bulk material by a field assisted sintering technique. A figure of merit of zT = 0.5 ± 0.09 at 450 °C and a peak zT of 0.8 ± 0.15 at 1000 °C could be achieved for a nanostructured, 0.8% phosphorus-doped Si80Ge20 alloy without any further optimization.

Gd silicide nanostructures epitaxially grown on Si(001) are studied by plan-view transmission electron microscopy and associated nanobeam electron diffraction, as well as scanning tunneling microscopy. The nanobeam diffraction measurements show a direct correlation between the nanostructure morphology, either nanowires or islands, and the silicide crystal structure. Scanning tunneling microscopy shows a phase transformation from nanowires to islands that nucleate at nanowire intersections. A specific mechanism for this transformation is proposed that explains nanowire growth behavior previously observed on vicinal Si surfaces.

Recent studies by a number of research groups have shown that the structure of epitaxial BiFeO3 (BFO) films changes drastically as a function of substrate-induced biaxial compression, with the crystal structure changing from one being nearly rhombohedral (R-like) to one being nearly tetragonal (T-like), where the “T-like” structure is characterized by a highly enhanced c/a ratio of out-of-plane c to in-plane a lattice parameters. In this work, we show that the critical compressive strain σc necessary to induce this transition can be reduced significantly by substituting 10% Ba for Bi [Bi0.9Ba0.1FeO3−δ (BBFO)] and that the “T-like” phase in both BBFO and BFO is stable up to the decomposition temperatures of the films in air. Furthermore, our results show that the BBFO solid solution shows clear ferromagnetic properties in contrast to its undoped BFO counterpart.

We present a versatile and flexible method to sequentially self-assemble micron-scale components at specific locations onto unconventional substrates, such as glass and plastic. In this method, components are independently batch fabricated and assembled onto a series of receptor sites incorporated onto a substrate in a fluid medium. Initially, all self-assembly sites are blocked with a photoresist polymer. Controlled light exposure can be used to remove the polymer and make a site available for receiving a microcomponent. By repeating this procedure, various microcomponents may be integrated onto specific locations on the substrate. To demonstrate the process, we prepared four types of 20 μm thick, 320 μm diameter circular silicon components and showed their optically controllable self-assembly in arrays of 640 receptor sites on glass and plastic with yields reaching 85%. The integration and operation of two types of functional components, red light-emitting diodes and silicon resistors, on plastic substrates was also demonstrated.

For development and integration of Si nanowires into nanoelectronic devices, an understanding of Ni silicide formation in electrical contacts to Si nanowires is necessary. Here, we examine the kinetics of Ni silicide phase formation. For Si nanowires with [111] growth directions, NiSi2 is the only phase to form in the temperature range 400–550 °C, and the NiSi2 growth exhibits linear kinetics from 400 to 500 °C with an activation energy of 0.76 ± 0.10 eV. In the case of Si nanowires with [112] growth directions, growth of the θ-Ni2Si phase in contact with the Si nanowire occurs with parabolic kinetics over the temperature range 400–550 °C, and an activation energy of 1.45 ± 0.07 eV/atom is extracted. Differences in the growth rates for Ni silicide phases with different SiNW growth directions implies that for simultaneous preparation of SiNW devices with Ni silicide contacts, SiNWs with the same growth direction are necessary.

Si80Ge20B0.6 thermoelectric alloys with minute erbium (Er) addition were prepared by the spark plasma sintering technique. The samples with different amounts of Er additions were analyzed by x-ray diffraction, x-ray fluorescence, and x-ray photoelectron spectroscopy. The thermoelectric properties were measured from 400 to 900 K. Effects of the amount of Er addition on the thermoelectric properties of Si80Ge20B0.6 alloys were investigated. New findings indicate that the Er-added alloys have larger carrier concentrations than the pristine sample. The larger carrier concentration appears to make a significant contribution to the electrical conductivity. Seebeck coefficient decreases with the increase of carrier concentration, whereas the power factor increases with increasing electrical conductivity. It was generally believed that the scattering of phonons by carriers may result in the thermal conductivity reduction. The samples with Er addition exhibit better figure of merits than the pristine sample. The optimal ratio of Er addition is actually in the range of 0.085–0.125 at.%.

A composite of boron nitride nanotubes (BNNTs) and iron (Fe) has been synthesized using a novel one-step process and characterized by optical, electron microscope, and mechanical measurement techniques. The BNNT–Fe composite, the first of this type produced to the best of our knowledge, is shown to have up to 24% higher specific yield strengths from stress–strain measurements and Rockwell Hardness C Scale (HRC), depth of penetration into sample of 120° diamond cone, 50% higher relative to a control sample of pure Fe. Scanning and transmission electron microscope imaging shows that the composite is comprised of a uniform nanoscale mixture of BNNTs bridging the metal particles.

Metallic nanostructures and specifically nanowires can be used for technological breakthroughs. Experimental measurements have provided insights on the mechanical properties of metallic nanostructures. In conjunction, modeling analyses provide an understanding of the underlying deformation and strengthening mechanisms in nanostructures. Most modeling studies on nanostructures are based on atomistic and molecular dynamics simulations, and though invaluable, they are limited to nanoscale dimensions of a few tens of nanometers, at small temporal scales, and physically unrealistic strain rates. Furthermore, most of the current applications for free-standing metallic nanostructures require high aspect ratios with at least one dimension greater than a few hundred nanometers. A continuum microstructurally based approach can, therefore, provide insights on design of one-dimensional nanowires on a physically relevant scale. Hence, we use a multiple-slip crystal plasticity formulation that is adapted to single crystal gold nanowires to simulate the experimental setup for a two-end fixed nanowire subjected to bending.

Thin film Cu-Ni alloys ranging from 2–8 nm were synthesized and their optical properties were measured as-deposited and after a laser treatment which dewet the films into arrays of spatially correlated nanoparticles. The resultant nanoparticle size and spacing are attributed to a laser induced spinodal dewetting process. The evolution of the spinodal dewetting process is investigated as a function of the thin film composition which ultimately dictates the size distribution and spacing of the nanoparticles. The optical measurements of the copper rich alloy nanoparticles reveal a signature absorption peak suggestive of a plasmon peak that red-shifts with increasing nanoparticle size and blue-shifts and dampens with increasing nickel concentration.