The oxidation behavior of polymer-derived SiAlCN ceramic in a water vapor environment was studied at 1400 °C. The oxidation and corrosion rates of the SiAlCN are much lower than those of SiCN and pure silicon-based ceramics. The material retains about 75% of its original strength after exposure in water vapor for 300 h at 1400 °C. It is believed that the superior resistance of the SiAlCN to water vapor-related oxidation and corrosion is due to the formation of an aluminum-doped silica layer, in which the aluminum has reduced the activity of the silica.

Nanosphere lithography fabricated nanostructures have highly tunable localized surface plasmons, which have been used for important sensing and spectroscopy applications. In this work, the authors focus on biological applications and technologies that utilize two types of related plasmonic phenomena: localized surface plasmon resonance (LSPR) spectroscopy and surface-enhanced Raman spectroscopy (SERS). Two applications of these plasmonic materials are presented: (i) the development of an ultrasensitive nanoscale optical biosensor based on LSPR wavelength-shift spectroscopy and (ii) the SERS detection of an anthrax biomarker.

Direct evidence of the transformation of WOx species in WO3 nanoclusters on WOx–ZrO2 system was achieved by high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy on samples obtained by a conventional precipitation method and annealed from 560 to 800 °C. WO3 Nanoclusters with 2-nm crystal size orthorhombic structure were identified on the ZrO2 surface after annealing at 800 °C.

An as-solidified structure of an Al-based ribbon sample produced by the melt-spinning technique was studied by x-ray diffractometry and transmission electron microscopy. The addition of Pd to Al-Y-Ni-Co alloys caused formation of the highly dispersed primary α-Al nanoparticles about 3–5 nm in size homogeneously embedded in the glassy matrix upon solidification. The first direct observation of microstrain and dislocations quenched in nanoparticles with a size below 7 nm is provided.

In this report, we present a new organometallic synthetic method to prepare nearly monodisperse InP nanoparticles using indium trifluoroacetate as the In precursor. Spherical particles of various sizes were prepared by modulating the growth duration. The optical and electrochemical properties were investigated and discussed with reference to band edge positions. This is the first report on the band edge position of quantum confined InP nanoparticles, which is a key parameter for development of electro-optic devices like solar cells and light-emitting diodes based on it.

Tin whisker growth has been observed since the 1950s and has become of more interest in the past 15 to 20 years due to the desire to use lead-free solders, pure tin being a good lead-free candidate. In the same time period, failure of satellites and other devices using pure tin solders has been blamed on tin whisker growth. The accepted driving force for whisker growth is compressive stresses in films. This article reports a microstructure-control method of limiting whisker growth through the introduction of pores that permit an alternate means of stress relief.

An aqueous nitrate metalorganic deposition (MOD) process was used to form a 30-nm-thick c-axis-textured ceria (CeO2) layer on a yttria-stabilized zirconia (YSZ) single-crystal substrate. X-ray diffraction showed the CeO2 layer was an (001) oriented film with a ω-scan full width at half-maximum of 1.47°. The average roughness of the ceria films, measured by atomic force microscopy, was about 5 nm. Critical current densities of up to 3.6 × 106 A/cm2 were measured on a 0.35-μm Ba2YCu3O7−x (YBCO) layer deposited over this cap layer using a trifluoroacetate (TFA)-based MOD ex situ process. The physical vapor deposition-derived ceria cap layer used in the most common coated conductor buffer layer stacks may be replaced by such a MOD processed film.

We briefly review our recent modeling of crystal nucleation and polycrystalline growth using a phase field theory. First, we consider the applicability of phase field theory for describing crystal nucleation in a model hard sphere fluid. It is shown that the phase field theory accurately predicts the nucleation barrier height for this liquid when the model parameters are fixed by independent molecular dynamics calculations. We then address various aspects of polycrystalline solidification and associated crystal pattern formation at relatively long timescales. This late stage growth regime, which is not accessible by molecular dynamics, involves nucleation at the growth front to create new crystal grains in addition to the effects of primary nucleation. Finally, we consider the limit of extreme polycrystalline growth, where the disordering effect due to prolific grain formation leads to isotropic growth patterns at long times, i.e., spherulite formation. Our model of spherulite growth exhibits branching at fixed grain misorientations, induced by the inclusion of a metastable minimum in the orientational free energy. It is demonstrated that a broad variety of spherulitic patterns can be recovered by changing only a few model parameters.

A graphite wafer has been implanted with Mg+ to produce a uniform Mg concentration. Subsequent H+ implantation covered the Mg+-implanted and -unimplanted regions. Ion-beam analysis shows a higher H retention in graphite embedded with Mg than in regions without Mg. A small amount of H diffuses out of the H+-implanted graphite during thermal annealing at temperatures up to 300 °C. However, significant H release from the region implanted with Mg+ and H+ ions occurs at 150 °C; further release is also observed at 300 °C. The results suggest that there are efficient H trapping centers and fast pathways for H diffusion in the Mg+-implanted graphite, which may prove highly desirable for reversible H storage.

Since the 1991 discovery of hollow cylindrical carbon-based unidimensional structures, the nanotubular form of matter has been thoroughly investigated leading to a wealth of literature. Their particular features are not limited to graphite but are common in many inorganic highly anisotropic two-dimensional layered compounds. The first non-mineral inorganic nanotubes, constituted of lamellar molybdenum and tungsten disulfides, were synthesized in 1992. Afterwards, a large number of inorganic nanotubes have been synthesized, opening the path to the development of nanoelectronics, due to their dielectric properties. The unique mineral phase that crystallizes with a tubular morphology is chrysotile, which has been tentatively used to prepare ultra-thin wires by filling its hollow nanodimensional core with a conductive material. To overcome its natural heterogeneity in composition, morphology, and structure, synthetic chrysotile-inspired nanotubes have been recently synthesized. These geoinspired nanotubes can be prepared with specific properties, finalized to focused achievements such as preparation of new quantum wires. The existing knowledge on the structural and physicochemical properties of mineral and synthetic chrysotile nanotubes is reviewed, with the aim of emphasizing their potential applications as nonlinear optical and conducting technological devices. Bibliography encompasses over one hundred references.

Aspects of mechanical deformability and biorheology of the human red blood cell are known to play a pivotal role in influencing organ function as well as states of overall health and disease. In this article, consequences of alterations to the membrane and cytoskeletal molecular structure of the human red blood cell are considered in the context of an infectious disease, Plasmodium falciparum malaria, and several hereditary hemolytic disorders: spherocytosis, elliptocytosis, and sickle cell anemia. In each of these cases, the effects of altered cell shape or molecular structure on cell elasticity, motility, and biorheology are examined. These examples are used to gain broad perspectives on the connections among cell and subcellular structure, properties, and disease at the intersections of engineering, biology, and medicine.

Using an infrared camera, we observed in situ dynamic shear-banding operations during compression of a bulk metallic glass at various strain rates. We demonstrated that the shear-banding events are highly dependent on strain rates, either intermittent at the lower strain rate or successive at the higher strain rate. Serrated plastic-flow behaviors are a result of shear-banding operations. These observations provide a new insight into inhomogeneous deformation of metallic glasses.

The mechanical properties of healthy and diseased bone tissue were extensively studied in mechanical tests. Most of this research was motivated by the immense costs of health care and social impacts due to osteoporosis in post-menopausal women and the aged. Osteoporosis results in bone loss and change of trabecular architecture, causing a decrease in bone strength. To address the problem of assessing local failure behavior of bone, we combined mechanical compression testing of trabecular bone samples with high-speed photography. In this exploratory study, we investigated healthy, osteoarthritic, and osteoporotic human vertebral trabecular bone compressed at high strain rates. Apparent strains were found to transfer into to a broad range of local strains. Strained trabeculae were seen to whiten with increasing strain. Comparison of whitened regions seen in high-speed photography sequences with scanning electron micrographs showed that the observed whitening was due to the formation of microcracks. From the results of a motion energy filter applied to the recorded movies, we saw that the whitened areas are, presumably, also areas of high deformation. In summary, high-speed photography allows the detection of microdamage in real time, leading toward a better understanding of the local processes involved in bone failure.

Carrier lifetime degradation in crystalline silicon solar cells under illumination with white light is a frequently observed phenomenon. Two main causes of such degradation effects have been identified in the past, both of them being electronically driven and both related to the most common acceptor element, boron, in silicon: (i) the dissociation of iron-boron pairs and (ii) the formation of recombination-active boron-oxygen complexes. While the first mechanism is particularly relevant in metal-contaminated solar-grade multicrystalline silicon materials, the latter process is important in monocrystalline Czochralski-grown silicon, rich in oxygen. This paper starts with a short review of the characteristic features of the two processes. We then briefly address the effect of iron-boron dissociation on solar cell parameters. Regarding the boron-oxygen-related degradation, the current status of the physical understanding of the defect formation process and the defect structure are presented. Finally, we discuss different strategies for effectively avoiding the degradation.

Powders of Zr, ZrO2, and ZrN were mixed and pressed to produce samples with different bulk stoichiometries in the ternary Zr–O–N systems. The samples were laser heated above melting, maintained at a high temperature, and quenched. The processed samples were cross-sectioned and studied using scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffraction. The results pointed to the location of the ternary invariant point Liquid + Gas + ZrO2 + ZrN on the high-temperature portion of the Zr–ZrO2–ZrN phase diagram. The ternary liquidus in the Zr–O–N system was further constrained based on the comparison of the results obtained in this work with composition histories of zirconium particles burning in air reported earlier. Elemental analysis of nitrogen-rich inclusions found in the samples showed the existence of an extended compositional range for ternary solid Zr–O–N solutions. X-ray diffraction analysis of the quenched samples indicated that these solutions are likely to be derived from the ZrN phase. A preliminary outline of the subsolidus ternary Zr–ZrO2–ZrN phase diagram is constructed based on these findings and the interpretations of the well-known binary Zr–O and Zr–N phase diagrams.

Since in instrumented indentation the contact area is indirectly measured from the contact depth, the natural and unavoidable roughness of real surfaces can induce some errors in determining the contact area and thus in calculating hardness and Young's modulus. To alleviate these possible errors and evaluate mechanical properties more precisely, here a simple contact model that takes into account the surface roughness is proposed. A series of instrumented indentations were made on W and Ni samples whose surface roughness is intentionally controlled, and the results are discussed in terms of the proposed model.