Materials Literature
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Ion beam assisted evaporation was used to deposit cubic and hexagonal boron nitride thin films. Boron was evaporated and bombardment was by argon and nitrogen ions. The effect of preparation conditions on the resulting phase was studied, and the relationship between the phase and the energy and momentum transferred in…
Two possible joints between different types of carbon tubules are discussed. Both joints introduce a single pentagon-heptagon pair into the perfect hexagon bonding pattern of the two tubules. These two types of joints can be used to form composite tubules in which every carbon atom is threefold coordinated. The first…
Using well-defined samples of SnO and ${\mathrm{SnO}}_{2}$, we have focused our attention on the way the two tin oxides could be distinguished using x-ray-photoemission spectroscopy (XPS). Polycrystalline SnO, oxidized in air to give ${\mathrm{SnO}}_{2}$, sputtered by argon-ion bombardment to give SnO and single-cryst…
The electronic structures of some possible carbon fibers nucleated from the hemisphere of a ${\mathrm{C}}_{60}$ molecule are presented. A one-dimensional electronic band-structure model of such carbon fibers, having not only rotational symmetry but also screw axes, is derived by folding the two-dimensional energy band…
Aluminosilicate molecular sieves with the FAU structure have been crystallized in the presence of several metallophthalocyanines. A percentage of the complexes becomes included into the zeolites. The synthesis of NaX around the metal chelate represents a new method for encapsulating such complexes and modifying zeolit…
Transmission measurements in the spectral range of 400-900 nm in conjunction with the Kramers-Kronig relation were used in calculating the optical constants (the refractive index n and the absorption index k) of In 2 Se 3 thin films deposited at room temperature on a glass substrate. The refractive index n has anomalo…
This chapter will provide a brief overview about the various strategies aimed at structural control of extended assemblies. The systems under consideration evolve in their dimensionality from
This chapter will provide a brief overview about the various strategies aimed at structural control of extended assemblies. The systems under consideration evolve in their dimensionality from (i) Two-Dimensional Assemblies: Thin Films, to (ii) Layered and Low-Dimensional Structures, and (iii) Three-Dimensional Framewo…
We have succeeded in measuring the polar anchoring energy of a nematic liquid crystal (5CB) aligned on rubbed polyimide films. The polar anchoring energy gradually weakens with increasing temperature and tends to zero as the nematic-isotropic (NI) transition temperature (35.3 °C) is approached. This indicates a strong…
A cathodic arc with beam filter is employed for the deposition of hydrogen-free amorphous carbon films. A linear filter is used to prevent macroparticles and nonionized carbon atoms from reaching the substrate. The deposited films are characterized by their optical and mechanical behavior. Depending on the deposition…
An interatomic potential for carbon is developed that is based on an empirical tight-binding approach. The model reproduces accurately the energy-versus-volume diagram of carbon polytypes and gives a good description of the phonons and elastic constants for carbon in the diamond and graphite structures. To test the tr…
A spatial light modulator design consisting of cascaded or sandwiched layers of ferroelectric liquid crystals (FLC's) is investigated. The interrelation between the FLC material, the polarization of the incident illumination, and the achievable modulation states is characterized. Magnitude modulation is accomplished b…
Studies in heterogeneous catalysis have long speculated on or have provided indirect evidence for the role of hydrogen embedded in the catalyst bulk as a primary reactant. This report describes experiments carried out under single-collision conditions that document the distinctive reactivity of hydrogen embedded in th…
Abstract This paper describes a modification of the split Hopkinson pressure bar, to allow compression testing of high strength metals at a strain rate of up to about 105 s–1. All dimensions are minimized to reduce effects of dispersion and inertia, with specimens of the order of 1 mm diameter. Strain is calculated fr…
A photoinduced magnetic moment has been observed in Cu and Al samples exposed to unpolarized visible light at low temperatures. It is shown that the light refected from a metal surface transfers some of its quasimomentum to conduction electrons. This mechanism creates surface currents which, for an appropriate geometr…
We discuss the implications of the classical Gauss-Bonnet formula to foam in two and three dimensions. For a two-dimensional foam it gives a generalization of the von Neumann law for the coarsening of foams to curved surfaces. As a consequence of this we find that the stability properties of stationary bubbles of such…
Reduction of S2O82− ions at the interface between an n-type porous Si electrode and an aqueous solution gives rise to electroluminescence showing evidence of quantization effects. A broad emission band with a maximum at 670 nm is observed similar to the photoluminescence spectrum of the same layers. The results sugges…
We examined the change in photoluminescence spectra of porous Si when it is oxidized then deoxidized chemically. After both steps, photoluminescence shifted to higher frequencies and increased in intensity. These shifts to higher frequencies indicate the photoluminescence is a result of the quantum size effect. Moreov…
The kinetics of the correlated annealing of pairs of neutral (F-H) and charged ( alpha -I) Frenkel defects in alkali halides is treated theoretically, taking into account defect diffusion, annihilation at short distances, and elastic or Coulomb interactions. It is shown that elastic interactions considerably affect th…
Magnetostriction temperature dependencies in Tb0.3Dy0.7 (Fe1−xMnx)2 were investigated. Mn substitution lowers the spin reorientation temperature, at which magnetostriction shows a sharp drop. Moreover, Mn containing compounds show larger magnetostriction than that for a Mn-free compound at low temperature. Mössbauer m…