Search results for " layer"

Magnetic-Field-Induced Locomotion of Glass Fibers on Water Surfaces: Towards the Understanding of How Much Force One Magnetic Nanoparticle Can Deliver

2009

Spray pyrolytic deposition of ZnO thin layers composed of low dimensional nanostructures

2010

Abstract ZnO nanolayers composed of fine nanostructures have been successively grown by spray pyrolytic deposition at 300  ∘ C over amorphous glass substrates. As deposited samples were analysed by scanning electron microscopy (SEM), showing a granular morphology with grain size in the limit of the microscope resolution. CL measurement shows a broad near band edge (3.4 eV) emission of ZnO in the UV region and the defect level emissions in the green region of the spectrum. The use of intermittent spray pyrolytic deposition is shown as an alternative to increase the homogeneity of the samples when temperatures near to the precursor pyrolytic decomposition is selected, long depositions times a…

Growth mode and self-organization of LuPc2on Si(001)-2×1vicinal surfaces: An optical investigation

2012

We report an investigation of the initial growth and of the self-organization of lutetium biphthalocyanine LuPc2 on Si(001)-2 x 1 vicinal surfaces. Using surface-sensitive optical spectroscopies, namely, surface-difference-reflectance spectroscopy (SDRS) and reflectance-anisotropy spectroscopy (RAS), together with local-probe microscopies, we are able to propose a scenario for the growth mode up to about 20 nm. We demonstrate that the growth mode initially proceeds through the formation of a wetting layer, followed by the formation of clusters whose sizes increase while keeping a constant shape in which the molecules are inclined. Moreover, the LuPc2 molecules are self-organized along the s…

Multiphysical modeling of dissimilar welding via interlayer

2011

Abstract A multiphysical finite element modeling of dissimilar welding via interlayer material was proposed. A 2D model including heat transfer, fluid flow and level set problems allowed to simulate the morphology and the composition of melted zone in horizontal plane. The calculated thickness of melted interlayer was used as a main criterion for the choice of optimal welding conditions, when the chemical interaction between the joined materials must be avoided. A 1D diffusion model at the limit of melted zone allowed estimating the length and the composition of diffusion layer between one of the materials and the interlayer basing on previously calculated local temperature gradient. The si…

Phase Composition and Nanoporous Structure of Core and Surface in the Modified Granules of NH4NO3

2018

The article deals with the study of phase composition and crystal nanoporous structure of core and surface layer of porous ammonium nitrate (PAN). The research results, presented in the article, show that the proposed way to generate PAN allows to provide the granule porous structure without changing of its phase composition. The crystal structure of granules after the humidification and heat treatment has some changes due to the increase of the number of pores. The change of crystal structure, in turn, allows to open access to nanopores that are located in the volume of granules. This allows to increase the holding capacity indicator of granules. An important result of conducted researches…

Suppression of Forward Electron Injection from Ru(dcbpy)2(NCS)2 to Nanocrystalline TiO2 Film As a Result of an Interfacial Al2O3 Barrier Layer Prepar…

2009

Subnanometer-thick Al2O3 barrier layers on nanocrystalline TiO2 film were prepared with atomic layer deposition (ALD). The method allowed variation of barrier thicknesses at atomic resolution also deep in nanoporous structures, which makes it a superior method as compared to, e.g., sol−gel techniques. In this letter we present results on the effect of Al2O3 barriers of various thicknesses on forward electron injection in dye-sensitized solar cells. A decrease in the amplitude of the oxidized Ru(dcbpy)2(NCS)2 dye absorption signal due to singlet injection was observed already after one deposition cycle that produces a discontinuous layer with nominal thickness of 1 A. More than two layer coa…

Structural and chemical analysis of annealed plasma-enhanced atomic layer deposition aluminum nitride films

2016

Plasma-enhanced atomic layer deposition was utilized to grow aluminum nitride (AlN) films on Si from trimethylaluminum and N2:H2 plasma at 200 °C. Thermal treatments were then applied on the films which caused changes in their chemical composition and nanostructure. These changes were observed to manifest in the refractive indices and densities of the films. The AlN films were identified to contain light element impurities, namely, H, C, and excess N due to nonideal precursor reactions. Oxygen contamination was also identified in the films. Many of the embedded impurities became volatile in the elevated annealing temperatures. Most notably, high amounts of H were observed to desorb from the…

Morphological evolution of InAs/InP quantum wires through aberration-corrected scanning transmission electron microscopy

2010

Evolution of the size, shape and composition of self-assembled InAs/InP quantum wires through the Stranski–Krastanov transition has been determined by aberration-corrected Z-contrast imaging. High resolution compositional maps of the wires in the initial, intermediate and final formation stages are presented. (001) is the main facet at their very initial stage of formation, which is gradually reduced in favour of {114} or {118}, ending with the formation of mature quantum wires with {114} facets. Significant changes in wire dimensions are measured when varying slightly the amount of InAs deposited. These results are used as input parameters to build three-dimensional models that allow calcu…

Photoluminescence Study of Defects in ZnO-Coated Polyacrylonitrile Nanofibers

2020

International audience; Core-shell nanostructures of one-dimensional (1D) polyacrylonitrile (PAN)/zinc oxide (ZnO) were obtained by combining atomic layer deposition (ALD) and electrospinning. Nanofibers with different ZnO thicknesses were synthesized and investigated. The present work offers novel information about 1D ZnO structural defects and activation energies (Ea) by performing photoluminescence (PL) measurements. PL measurements of 1D ZnO/PAN samples were investigated from 77 K to 273 K (room temperature). By analyzing the obtained data of the emission spectrum, Ea and temperature coefficients were calculated. The results let us suggest an approximate model of defects in 1D ZnO/PAN s…

From dots to doughnuts: Two-dimensionally confined deposition of polyelectrolytes on block copolymer templates

2016

© 2016 Elsevier Ltd The combination of block copolymer templating with electrostatic self-assembly provides a simple and robust method for creating nano-patterned polyelectrolyte multilayers over large areas. The deposition of the first polyelectrolyte layer provides important insights on the initial stages of multilayer buildup. Here, we focus on two-dimensionally confined “dots” patterns afforded by block copolymer films featuring hexagonally-packed cylinders that are oriented normal to the substrate. Rendering the cylinder caps positively charged enables the selective deposition of negatively charged polyelectrolytes on them under salt-free conditions. The initially formed polyelectrolyt…