Materials Literature
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The electronic structure and the chemical bonding mechanism of silver oxide are studied on the basis of band-structure calculations, using the full-potential linearized augmented-plane-wave (FLAPW) method. Our calculations indicate that silver oxide is a metal (or a semi-metal). Total and partial densities of states a…
The simultaneous application of low intensity optical and static electric fields to photoisomerizable electro-optic materials is shown to allow manipulation of the refractive index. A dc electric field was applied to the sample by means of a corona poling mechanism, which was illuminated within the absorption band usi…
Polyvinylalcohol (PVA) films, filled with mass fractions % of , were prepared. The x-ray diffraction spectra indicated the partial crystallinity of PVA, which decays as w increases. The infrared analysis implied that the degree of syndiotacticity depends, nonmonotonically, on w . The observed peak at 520 nm, in the ul…
We prepared oxygen stoichiometric and in which tetravalent terbium ions are stabilized at the B sites of the perovskite . Their crystal structures at room temperature and at 10 K were determined from both x-ray and neutron diffraction measurements. Both and have an orthorhombic perovskite-type structure with space gro…
La and Nd gallates are currently being used as substrate materials for high temperature superconductor thin film deposition. In this work we have synthesized and characterized by means of XRD and Raman spectroscopy solid solutions of the type . Polarized Raman study of and single crystals is also performed. Our result…
The 2-orbital Kondo model with classical Jahn-Teller phonons is studied using Monte Carlo techniques. The observed phase diagram is rich and includes a novel regime of phase separation induced by the orbital degrees of freedom. Experimental consequences of our results are discussed. In addition, the optical conductivi…
Pinning type coercivity has been induced in large $(\ensuremath{\approx}50\ensuremath{\mu}\mathrm{m})$ particles of $\mathrm{Sm}{}_{2}\mathrm{Fe}{}_{17}\mathrm{N}{}_{3}$ by irradiation with 5 GeV $\mathrm{Pb}{}^{56+}$ ions. M\"ossbauer spectroscopy is used to analyze the structure of the defects and estimate their vol…
In this work, we present results from a ball-milling experiment carried out simultaneously on (a) spinel and (b) its precursor mixture , to investigate their evolution under identical conditions. Partial reversibility of the reaction was observed, resulting in nearly equal phase composition for both systems after 420…
Carbon nitride particles of nm size were prepared in an induction thermal plasma treatment of carbon powder including a small amount of nitrogen. Relatively large ones of about 5 nm in diameter are mostly in a dodecahedral shape. The structure was analyzed by high-resolution transmission electron microscopy and electr…
A thin (∼2 nm thick) amorphous diamond coating was prepared on single crystal silicon tip arrays by using a filtered vacuum arc plasma deposition technique. The coating has a microscopically uniform morphology. As compared to uncoated tips, the electron emission of the coated tip arrays is enhanced, showing an increas…
Ambipolar carrier transport properties in different phases of a liquid-crystalline photoconductor, 2-(4-octylphenyl)–6-n-butoxynaphthalene, were investigated by a time-of-flight technique. Carrier mobilities were increased stepwise when phase transition took place as the temperature decreased. The smectic E phase in t…
The electron field-emission properties of hydrogenated amorphous carbon and nitrogenated tetrahedral amorphous carbon thin films are examined by measuring the field-emission current as a function of the applied macroscopic electric field. The experimental results indicate the existence of an optimum film thickness for…
STM imaging of single-wall carbon nanotubes has recently been achieved with atomic resolution, revealing the chirality of the carbon network. In this work, a theoretical modeling of scanning tunneling microscopy of the nanotubes is presented, based on a tight-binding $\ensuremath{\pi}$-electron Hamiltonian. This theor…
Molecular simulations show that shear strains arising from liquid flow cause local minima of the potential-energy surface to disappear, leading to mechanical instabilities which force the system towards alternate local minima. Associated with these mechanical instabilities are irreversible atomic displacements, which…
We experiment with a massively parallel implementation of an algorithm for simulating the dynamics of metastable decay in kinetic Ising models. The parallel scheme is directly applicable to a wide range of stochastic cellular automata where the discrete events (updates) are Poisson arrivals. For high performance, we u…
Doped alkaline–bismuth–titanate perovskite single crystals have been grown in ferroelectric phases with high piezoelectric actuation. Rhombohedral-phase Na1/2Bi1/2TiO3–BaTiO3 crystals exhibit up to 0.25% free strain with low hysteresis along the cubic 〈001〉 direction (d33∼450 pC/N). Tetragonal phase crystals exhibit f…
To improve the transparency, flexibility, and solubility of polyimide, and to fabricate a negative working photoresist, polyamic acid, polyurea, and poly(amic acid-co-urea) in various contents were synthesized. Photosensitive diazoresin was synthesized and was used as the photocrosslinking agent. Characteristics of th…
The fibrillar and the lamellar structures in a range of poly(ethylene terephthalate) fibers were studied by small-angle X-ray scattering. The intensity maxima in the lamellar peaks lie on a curve that can be described as an ellipse. Therefore, the two-dimensional images were analyzed in elliptical coordinates. The dim…
A software program for experimental design and response surface methodology (RSM) was used to set up and evaluate the effect of modifiers in mixed polyolefin fractions. Sheet extruded blends of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), 2 different high-density polyethylenes (HDPE) and 2…
Various bismaleimide-diamine Michael addition type prepolymers were prepared through melt condensation and using acetone, dimethylformamide, and m-cresol as solvents in a molar ratio of 1 : 1. Structures of the prepolymers, such as terminal moieties and molecular weight of main chain, depended strongly on the preparat…