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[en] We report the formation and directed self-assembly of sub-10 nm half-pitch line patterns from lamellar microdomains of a block copolymer hybrid. The hybrid, which is a mixture of poly(styrene-b-ethylene oxide) (PS-b-PEO) and a low molecular weight organosilicate (OS), shows strong segregation between two phases (i.e. PS and PEO+OS) and forms lamellar microdomains of down to approximately 7 nm in half-pitch. Patterns applicable to multifinger device layouts are created by self-assembling the hybrid on topographic pre-patterns with a chemically non-selective surface. With careful design of the guiding topographic pattern geometry, well-controlled lateral placement including bent structures of lamellar microdomains can be obtained by this approach.
[en] Au(111) vicinal surfaces are characteristic examples of two-phase segregation or faceting. Between ∼4 deg. and 9.5 deg. miscut, the surface exhibits hill-and-valley structures formed by bunches of relatively wide (dw∼36-41 A) and narrow (dn∼14 A) terraces. The evolution of surface electronic states in such a faceted system is followed using a curved crystal. Beyond 4 deg. the surface state splits into distinct dw and dn bands. Our analysis suggests the crucial role of surface states in defining the characteristic dw and dn sizes during Au faceting.
[en] Schottky-barrier changes by the segregation and structural disorder are studied using the first-principles calculations and adopting Au/Si interface. The Schottky barrier for electrons simply decreases as increasing the valency of segregated atoms from II to VI families, which variation is shown closely related to how the Si atoms are terminated at the interface. On the other hand, the structural disorders (defects) prefer to locate near the interface and the Schottky barrier for hole carriers does not change in cases of Si vacancy and Au substitution, while it increases in cases of Si and Au interstitials reflecting the appearance of Si dangling bonds.
[en] We discuss recent work on reaction-diffusion processes that take place on complex networks. The inherent inhomogeneity of the substrate leads to a series of new phenomena, which bear only a small resemblance to the classical results of the field. The annihilation rate is abnormally high in such systems, while at the same time depletion zones are absent in the A+A→ 0 reaction and no segregation is observed for the A+B →0 reaction. These results are mainly attributed to the presence of network hubs and to the small network diameter of such systems
[en] X-ray photoelectron spectroscopy, scanning electron microscopy and impedance dispersion spectroscopy have been used to study the segregation behaviour of yttrium and impurities in yttria-tetragonal polycrystals (Y-TZP). Sintered and polished specimens of 2 Y-TZP's with different levels of impurities were annealed between 800 and 1500 deg C. On annealing, significant amounts of impurity silicates and yttrium incorporated into the silicate, segregated to the external surface of specimens, even at low annealing temperatures. The segregation layer increased with increasing annealing temperature. Impedance spectroscopy indicated that grain boundary cleaning accompanied redistribution of the silicate phase to the external surface. The segregation of silicate phases at the external surface led to yttrium redistribution in the surface grains and enhanced grain growth. (author). 22 refs.; 12 figs.; 1 tab
[en] It has been known for a long time that many mixtures of granular materials tend to segregate when tumbled in a rotating horizontal cylinder, with the different components separating into bands of relatively pure single concentration along the rotational axis [Mixing of Solids, Advances in Chemical Eng., edited by T. B. Drew and J. W. Hoopes (Academic Press, New York, 1952), Vol. 2, p. 211]. Here we report a phenomenon that seems to be analogous, but in suspensions of monodisperse neutrally buoyant spherical particles in a Newtonian liquid medium being sheared in a partially filled horizontal Couette device in which the suspension separates itself into alternating regions of high and low particle concentration along the length of the tube. The experiment is mostly qualitative, the aim at this stage being primarily to provide photographic evidence of a curious and as yet unexplained phenomenon. copyright 1999 American Institute of Physics