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Oriented Growth (oriented + growth)
Selected AbstractsOne-Nanometer-Thick Seed Layer of Unilamellar Nanosheets Promotes Oriented Growth of Oxide Crystal Films,ADVANCED MATERIALS, Issue 2 2008T. Shibata Room-temperature fabrication of an ultimately thin seed layer using 2D oxide nanosheets is demonstrated. Flat nanosheets are tiled to form a highly organized monolayer with a thickness of ca. 1 nm on a glass substrate (see figure). Monolayer films of nanosheets such as Ca2Nb3O10 (2D square lattice) and MnO2 (2D hexagonal) successfully promote oriented film growth of oxide crystals such as SrTiO3 (cubic), TiO2 (tetragonal), and ZnO (hexagonal). [source] The initiation and development of metamorphic foliation in the Otago Schist, Part 1: competitive oriented growth of white micaJOURNAL OF METAMORPHIC GEOLOGY, Issue 6 2005A. STALLARD Abstract The 3D shape, size and orientation data for white mica grains sampled along two transects of increasing metamorphic grade in the Otago Schist, New Zealand, reveal that metamorphic foliation, as defined by mica shape-preferred orientation (SPO), developed rapidly at sub-greenschist facies conditions early in the deformation history. The onset of penetrative strain metamorphism is marked by the rapid elimination of poorly oriented large clastic mica in favour of numerous new smaller grains of contrasting composition, higher aspect ratios and a strong preferred orientation. The metamorphic mica is blade shaped with long axes defining the linear aspect of the foliation and intermediate axes a partial girdle about the lineation. Once initiated, foliation progressively intensified by an increase in the aspect ratio, size and alignment of grains, although highest grade samples within the chlorite zone record a decrease in aspect ratio and reduction in SPO strength despite continued increase in grain size. These trends are interpreted in terms of progressive competitive anisotropic growth of blade-shaped grains so that the fastest growth directions and blade lengths tend to parallel the extension direction during deformation. The competitive nature of mica growth is indicated by the progressive increase in size and resultant decrease in number of metamorphic mica with increasing grade, from c. 1000 relatively small mica grains per square millimetre of thin section at lower grades, to c. 100 relatively large grains per square millimetre in higher grade samples. Reversal of SPO intensity and grain aspect ratio trends in higher grade samples may reflect a reduction in the strain rate or reduction in the deviatoric component of the stress field. [source] Controlled Crystallization of Calcite Under Surface Electric Field Due to Polarized Hydroxyapatite CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2009Norio Wada We examined effects of surface electric fields for the crystallization of calcite on polarized hydroxyapatite ceramics with and without polyacrylic acid (PAA) as soluble additive. Both on negatively and positively charged surfaces without PAA, the only precipitates were rhombohedra calcite crystals with the face of the {10.4} plane favorably oriented parallel to the surfaces. This oriented growth was explained by the nucleation theory in the presence of an external electric field. However, the addition of PAA drastically changed the situation of the calcite crystals, i.e., the crystallites were the hemispheric aggregates of calcite needles with a facetted rhombohedral {10.4} end face and flat island-shaped aggregates of ones with a rough (00.1) end face having a triangular shape. The calcite needles grew along the crystallographic [00.1] axis. This oriented growth was explained by epitaxy on the PAA,Ca2+ complexes adsorbing on the surfaces. The morphology of the PAA,Ca2+ complex assemblies adsorbing on the surfaces before the calcite nucleation was an important factor to control the structure of calcite aggregates formed following. This morphology was controlled by properties of the surface electric field and the spatial distribution of the negatively and positively charged sites in the PAA,Ca2+ complexes. [source] Ga-doped ZnO transparent conducting films prepared by helicon-wave-excited plasma sputteringPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2009Shingo Masaki Abstract Gallium-doped zinc oxide (ZnO:Ga) transparent conducting films were prepared by the helicon-wave-excited plasma sputtering (HWPS) method. The films exhibited a dominant [0001]-oriented growth with a small full width at half maximum of the (0002) ZnO diffraction peak (0.28 degrees). A high optical transmittance greater than 80% was achieved in the wavelength range between 400 and 1600 nm, because the HWPS method essentially does not damage the film surface. The results indicate that CdS-free Cu(In,Ga)Se2 -based solar cells may be fabricated by sputtering ZnO:Ga directly on the Cu(In,Ga)Se2 layer using the HWPS method. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growing ZnO Crystals on Magnetite NanoparticlesCHEMISTRY - A EUROPEAN JOURNAL, Issue 7 2004Rachel Turgeman Abstract We report herein on the oriented growth of ZnO crystals on magnetite nanoparticles. The ZnO crystals were grown by hydrolyzing a supersaturated aqueous solution of zinc nitrate. The seeds for the growth were magnetite nanoparticles with a diameter of 5.7 nm and a narrow size distribution. Hollowed ZnO hexagons of 0.15 ,m width and 0.5 ,m length filled with Fe3O4 particles were obtained. HR-TEM (high-resolution transmission electron microscopy) and selected-area EDS (energy-dispersive spectroscopy) show that the nanoparticles are homogenously spread in the ZnO tubes. Zeta potential measurements were employed to understand the relationship between the nanoparticles and the oriented growth of the ZnO crystals. The results show that the surfactants induced the directional growth of the ZnO crystals. [source] | ||||||||||