Materials Literature
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The phase Hamiltonian of armchair carbon nanotubes at half filling and away from it is derived from the microscopic lattice model by taking the long-range Coulomb interaction into account. We investigate the low-energy properties of the system using the renormalization group method. At half filling, the ground state i…
Using scanning tunneling microscopy, low-energy ion scattering, and quantitative low-energy electron diffraction, we find about $17%$ metal vacancies on the oxygen-covered Cr(100) surface. The oxygen atoms occupy all the hollow sites of the first layer, including those neighboring a Cr vacancy. We argue that the vacan…
A parallel approach for fabricating nanocrystal-based semiconductor–insulator–metal tunnel diodes is presented. The devices consisted of a Au electrode, a monolayer of 38 Å CdSe nanocrystals, an insulating bilayer of eicosanoic acid (C19H39CO2H), and an Al electrode. Each device was approximately 100 μm2. Conductance…
We report on a photoinduced phenomenon in solids, namely, photomelting at low temperature. We have found that both trigonal and amorphous selenium can be molten by illumination with light at a temperature of ∼77 K. This phenomenon is pure optical (athermal) and it is associated with light-induced breaking of the inter…
A simple method of making reliable electrical contact to multiwalled carbon nanotubes is described. With these contacts, current in the mA range can be routinely passed through individual multiwalled nanotubes without adverse consequences, thus allowing their resistance to be measured using a common multimeter. The co…
We have fabricated light-emitting diodes (LEDs) with Schottky contacts on a single ultrathin amorphous silicon (Si) layer containing Si nanocrystals formed by simple techniques as used for standard Si devices. Orange electroluminescence (EL) from these LEDs could be seen with the naked eye at room temperature when a r…
Magnetic tunneling junctions are fabricated from epitaxially grown La0.8Sr0.2MnO3/SrTiO3/La0.8Sr0.2MnO3 trilayers. A large tunneling magnetoresistance of 150% is observed for a junction with a thin barrier layer (1.6 nm) under a low switching field (<10 Oe) at 5 K. A small tunneling magnetoresistance is observe…
Third-order optical nonlinearity of the carbon nanotubes was investigated with both 30-ps-wide and 8-ns-wide Nd:YAG laser beams. Both 1064 and 532 nm were used in each case. The nonlinear optical temporal response was obtained both on the picosecond scale and on the nanosecond scale, and the corresponding mechanism is…
Compression of purified, unoriented, highly crystalline single-wall carbon nanotube material reveals an exceptionally large and reversible volume reduction. Density increases rapidly with increasing pressure, approaching that of graphite, and recovers completely upon pressure release. The reversible work done in compr…
The three-dimensional orientation of polarization vectors at the surface of ferroelectric barium–titanate (BaTiO3) ceramics is evaluated using voltage-modulated scanning force microscopy (SFM). By applying an ac voltage to the conductive SFM tip, we measure the relative amount of the three orthogonal components Px, Py…
The electrochromic mechanism in amorphous tungsten oxide films is studied using Raman scattering measurements. The Raman spectra of as-deposited films show two strong peaks at 770 and 950 cm−1 due to vibrations of the W6+–O and W6+=O bonds, respectively, and a weaker peak at 220 cm−1 that we attribute to the W4+–O bon…
Colossal negative magnetoresistance Δρ(T,B) observed in La(0.6)Y(0.1)Ca(0.3)MnO(3) at B=1T shows a nearly perfect symmetry around T_0=160K suggesting a universal field-induced transport mechanism in this material. Attributing this symmetry to strong magnetic fluctuations (triggered by the Y substitution and further en…
The free volume of a bisphenol-A-type epoxide oligomer (DGEBA) was studied using Williams–Landel–Ferry parameters and thermal expansion coefficients above and below the glass transition temperature (Tg). The values of the free-volume fraction at the Tg are around 0.02 for the DGEBA oligomers having weight-average mole…
The structures and properties of BR/CR/SBS blends were studied by using optical, electron microscopy, FTIR methods, etc. Results showed that the addition of a small amount of SBS to the thermodynamically immiscible blends BR/CR could significantly promote fine and homogeneous dispersion of the system, increase crossli…
We present the results of an experimental and numerical study of the effects of a steady magnetic field on sidewall convection in molten gallium. The magnetic field is applied in a direction which is orthogonal to the main flow which reduces the convection and good agreement is found for the scaling of this effect wit…
This paper reports on the influence of maleated polypropylene (MAPP) on the properties of polypropylene (PP)/newspaper flour (PF) composite, and the compatibilization mechanism was also studied. The results of mechanical tests and scanning electron microscope (SEM) showed that MAPP was a true coupling agent for PP/PF…
The fabrication of near-micrometer-sized close-packed coherent microlens arrays on spheric or aspheric surfaces has been accomplished by use of a compact holographic projector system that was developed for producing multimicrometer down to submicrometer grid patterning on curved surfaces. The microlens arrays, which c…
Modification of polyolefin surfaces is often necessary to achieve improved printability, lamination, etc. Although corona discharge and flame treatments can produce the higher surface energy needed for these applications, the properties of the resulting surfaces are not always optimal. Atmospheric pressure plasma is a…
The coordinate-transformation-based differential method of Chandezon et al. [J. Opt. (Paris) 11, 235 (1980); J. Opt. Soc. Am. 72, 839 (1982)] (the C method) is one of the simplest and most versatile methods for modeling surface-relief gratings. However, to date it has been used by only a small number of people, probab…
Despite occasional references in the older literature to the ability of gold to catalyze certain reactions, the metal has until recently had the reputation of being one of the least catalytically useful. The recent discovery that some supported gold catalysts can affect the oxidation of carbon monoxide at or below amb…