Simulations of TiO2(both rutile and anatase) nanoparticles with water, methanol, and formic acid were conducted using a ReaxFF reactive force field to investigate the characteristic behavior of reactivity to these organic solvents. The force field was validated by comparing water dissociative adsorption percentage and bond length between Na and O with density functional theory (DFT) and experimental results. In the simulations, 1-nm rutile and anatase nanoparticles with water, methanol, and formic acid were used, respectively. The numbers of attached hydroxyl with time and nanoparticles distortion levels are presented. We found that the rutile nanoparticle is more reactive than the anatase nanoparticle and that formic acid distorts nanoparticles more than water and methanol.

Branched core–shell hybrids of tin nanowires and carbon nanotubes have been successfully obtained on silicon substrate via a self-assembly process by chemical vapor deposition. Structure characterization unveiled that the nanostructures are the hybrids of branched single-crystalline β-Sn nanowires coated with amorphous carbon nanotubes. Detailed investigation demonstrates that the amount of introduced ethylene plays a crucial role in triggering the morphology change of the product from freestanding core–shell hybrids to branched hybrids accompanying with a thickness and surface morphology change of carbon shell. Architecture of the branched core–shell hybrids has been categorized and the mechanism has been discussed. This kind of branched hybrids may find great potential applications in building multipath nanoelectronic components, lithium-ion battery electrodes, and enhanced superconducting nanodevices as well.

Storage is the main problem to use hydrogen as a fuel in the car industry. Porous carbons are promising storage materials. We have performed computer simulations to investigate carbide-derived porous carbons, showing that these materials exhibit a structure of connected pores with graphitic walls. We then apply a thermodynamic model to evaluate the hydrogen storage. The model accounts for the quantum effects of the motion of the molecules in the pores. The pore widths optimizing the storage depend on pore shape, temperature, and pressure. At 300 K and 10 MPa, the optimal widths lie in the range 6–10 Å. The predictions are consistent with experiment. The calculated storage capacities fall below the targets proposed by the U.S. Department of Energy. This is a consequence of the weak interaction between hydrogen and the pore walls. Metallic doping enhances the binding energy of hydrogen to the walls, which has promising consequences for hydrogen storage.

The effect of Al doping on the reflective properties of TiO2 nanoparticles, synthesized by sol–gel method, has been investigated. It has been observed that with Al doping, the phase transition temperature for anatase to rutile phase increases; however, no change in morphology has been observed. No additional absorption edge was found in the absorption spectra, but a weak luminescent peak was noticed in the photoluminescence spectra. TiO2nanoparticles with 0.1% Al doping show higher photostability with practically no change in reflectance. A coating material has been prepared by dispersing these synthesized nanoparticles in water solution of organic binder. Coating material parameters such as pigment to binder weight ratio, solvent ratio, pH of solution have been taken into care to make the coating material flowable with good ability to adhere. Their coating was applied on a plastic substrate with different coating thicknesses to design light reflectors. These reflectors have been found to have diffuse reflectance of 98.17–98.29% for the 0.25-mm-thick coating.

The composite nature of mineralized natural materials is achieved through both the microstructural inclusion of an organic component and an overall microstructure that is controlled by templating onto organic macromolecules. A modification of an existing laboratory technique is developed for the codeposition of a CaCO3–gelatin composite with a controllable organic content. First, calibration curves are developed to determine the organic content of a CaCO3–gelatin composite from infrared spectra. Second, a CaCO3–gelatin composite is deposited on either glass coverslips or demineralized eggshell membranes using an automated alternating soaking process. Electron microscopy images and use of the infrared spectra calibration curves show that by altering the amount of gelatin in the ionic growth solutions, the final organic component of the mineral can be regulated over the range of 1–10%, similar to that of natural eggshell.

In this article we develop an analytical theory that correlates the macroscopic curvature of stressed film/substrate systems with the microscopic in-plane and out-of-plane deflections of planar rotators. We have extended these stress-deflection relations in the case of nonlinear stress fields and validated the results with the aid of finite element simulations. We use this theory to study the heteroepitaxial growth of cubic silicon carbide on silicon (100) and discovered that, due to defects generated on the silicon substrate during the carbonization process, wafer curvature techniques alone may not enable determination of the stress field in the grown films either quantitatively or qualitatively.

We report the mechanical behavior of vertically aligned carbon nanotube films, grown on Si substrates using atmospheric pressure chemical vapor deposition, subjected to in situ large displacement (up to 70 μm) flat-punch indentations. We observed three distinct regimes in their indentation stress–strain curves: (i) a short elastic regime, followed by (ii) a sudden instability, which resulted in a substantial rapid displacement burst manifested by an instantaneous vertical shearing of the material directly underneath the indenter tip by as much as 30 μm, and (iii) a positively sloped plateau for displacements between 10 and 70 μm. In situ nanomechanical indentation experiments revealed that the shear strain was accommodated by an array of coiled carbon nanotube “microrollers,” providing a low-friction path for the vertical displacement. Mechanical response and concurrent deformation morphologies are discussed in the foam-like deformation framework with a particular emphasis on boundary conditions.

To study the effect of nanotwins on thermal stability, a comprehensive characterization study was performed on two types of ultrafine grained (UFG) copper samples, with and without nanotwins. The two samples were sequentially heat-treated at elevated temperatures, and the grain size, grain boundary character, and texture were characterized after each heat treatment. The as-prepared nanotwinned (nt) copper foil had an average columnar grain size of ∼700 nm with a high density of coherent twin boundaries (CTBs) (twin thickness, ∼40 nm), which remained stable up to 300 °C. In contrast, the other UFG sample had few CTBs, and rapid grain growth was observed at 200 °C. The thermal stability of nt copper is discussed with respect to the presence of the low energy nanotwins, triple junctions between the twins and columnar grains, texture and grain growth.