Materials Literature
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Poly- p -phenylenebenzobisoxazole (PBO) and carbon nanotubes have a fully conjugated rod-like backbone entailing excellent mechanical properties, thermo-oxidative stability and solvent resistance. Rigid-rod PBO is commonly processed by dissolving in methanesulfonic acid or Lewis acid. A multi-wall carbon nanotube (MWN…
Abstract Epoxy‐siloxane hybrids (bi‐continuous nanocomposites) were produced from mixtures of a silane‐functionalized resin and tetra‐ethoxysilane by the sol‐gel method. Absorption of tetrahydrofuran (THF) in thin samples was found to take place by a two‐stage process, consisting of an induction period and a subsequen…
The self-synthesis of tungsten oxide (W18O49) nanowires on sputter-deposited WCx films using a simple annealing/oxidization process was reported. It was found that thermal annealing of WCx films at 680°C for 30min in nitrogen followed by oxidation at 450°C for 30min in pure oxygen would yield dense and well-crystalliz…
We demonstrate here that single-crystal β-Ni(OH) 2 nanosheets can be selectively synthesized in large quantities through a facile hydrothermal synthetic method using aqueous nickel nitrate as the nickel source and sodium hydroxide as alkaline reagent. This attempt is based on the treatment of aqueous nickel nitrate wi…
YAlO 3 and NdGaO3 thermal expansion coefficients were measured using in situ powder x-ray diffraction in the temperature range of 28–650 °C. They exhibit a clear anisotropy: The expansion, quite similar along the [100] and [001] directions, is much lower along the [010] direction. The formation of cracks observed in Y…
Single crystalline ZnO thin films were heteroepitaxially grown on sapphire substrates by rf-magnetron sputtering. The ZnO films on sapphire A and C face were oriented along the (0001) direction, whereas the ZnO film on sapphire R face was oriented along the (11-20) direction. The rate of photoinduced hydrophilic conve…
Semiconductor nanostructures in biological applications are discussed. Results are presented on the use of colloidal semiconductor quantum dots both as biological tags and as structures that interact with and influence biomolecules. Results are presented on the use of semiconducting carbon nanotubes in biological appl…
Copper ferrite films have been deposited on (100) MgO substrates by pulsed-laser deposition. The oxygen pressure used in deposition was varied from 1to120mTorr with the substrate temperature fixed at 700°C. Magnetization values are measured to increase with oxygen pressure, reaching a maximum value of 2480G, which is…
A semiautomated device for solubility measurements in solution volumes as low as 1 mL was developed for pharmaceutical applications. The device operates nonisothermally, and can measure multiple samples simultaneously. Solubilities of model compounds such as paracetamol, mannitol, adipic acid, and glycine were measure…
Mass production of quasi-one-dimensional gallium oxide nanobelts is accomplished through graphite-thermal reduction of a mixture of gallium oxide powders and SnO2 nanopowders under controlled experimental conditions. Sn nanoparticles are located at or close to the tips of the nanobelts and served as the catalyst for t…
Single-crystal nanowires of zinc oxide were prepared by a novel self-seeded vapour–liquid–solid (VLS) growth method using ultrasonic spray-assisted chemical vapour deposition, in which liquid Zn droplets were used as ‘catalysts’. In this approach, a nanocrystalline seed layer was first deposited, by direct decompositi…
Undoped and Ce-doped Ba 0.5 Sr 0.5 TiO 3 (BST) thin films were prepared by pulsed-laser deposition onto a Nb-doped SrTiO 3 (STON) substrate. The Ce concentration, ranging from 0.5 to 1.0 at.%, was found to have a strong influence on the electric properties of films at room temperature. We find that, with a positively…
The orbital excitations of a series of transition-metal compounds are studied by means of optical spectroscopy. Our aim was to identify signatures of collective orbital excitations by comparison with experimental and theoretical results for predominantly local crystal-field excitations. To this end, we have studied Ti…
Molecular simulation techniques are used to find the basal spacing of organoclay on the basis of the energy minimum, using the canonical NVT ensemble. Then, the interlayer structure and mobility of alkyl chains are explored based on the interlayer atomic density profiles. Besides the basic lateral-monolayer arrangemen…
This work investigates the evolution of micro-Raman spectra of a [001]-oriented 0.67Pb(Mg1∕3Nb2∕3)O3–0.33PbTiO3 single crystal in the temperature range from −120 to 200 °C. For a poled sample, the T1u mode splits into an E mode (remaining at 51cm−1) and a new A1 mode (shifting to 95cm−1 at −120°C) at the tetragonal to…
The field emission characteristics of multiwalled carbon nanotubes at various temperatures are studied. It is found that the turn-on field and emission current at a given applied electric field are dependent on the ambient temperature of the nanotube. This dependence is believed to be due to the change in the work fun…
We present a floating-potential dielectrophoresis method used for the first time to achieve controlled alignment of an individual semiconducting or metallic single-walled carbon nanotube (SWCNT) between two electrical contacts with high repeatability. This result is significantly different from previous reports, in wh…
The fracture behavior of semicrystalline polymers is controlled by the micromechanisms associated with formation and breakdown of a plastic deformation region at notches, cracks, or other stress raising defects. In this context, it is widely acknowledged that material toughness may arise from the volume of the plastic…
Conditions for inception of dc corona discharges in air near spherical and cylindrical anodes are considered. The parameter K (ionization integral) in the standard discharge inception criterion is evaluated for a wide range of electrode radii and air densities.
The role of Ti in improving the thermodynamics of hydrogen desorption in crystalline sodium alanate (NaAlH4) has been investigated by using the density functional theory. The total energy calculations reveal that Ti prefers to occupy the Na site over that of the Al site when the atomic energies are used as the referen…