Preferential Orientation (preferential + orientation)

Distribution by Scientific Domains


Selected Abstracts


Magnetic and Transport Properties of Zn0.4Fe2.6O4 Thin Films with Highly Preferential Orientation

CHEMINFORM, Issue 13 2007
Z. L. Lu
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]


Nanocrystalline transparent SnO2 -ZnO films fabricated at lower substrate temperature using a low-cost and simplified spray technique

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2010
K. Ravichandran
Abstract Nanocrystalline and transparent conducting SnO2 - ZnO films were fabricated by employing an inexpensive, simplified spray technique using a perfume atomizer at relatively low substrate temperature (360±5 °C) compared with conventional spray method. The structural studies reveal that the SnO2 -ZnO films are polycrystalline in nature with preferential orientation along the (101) plane. The dislocation density is very low (1.48×1015lines/m2), indicating the good crystallinity of the films. The crystallite size of the films was found to be in the range of 26,34 nm. The optical transmittance in the visible range and the optical band gap are 85% and 3.6 eV respectively. The sheet resistance increases from 8.74 k,/, to 32.4 k,/, as the zinc concentration increases from 0 to 40 at.%. The films were found to have desirable figure of merit (1.63×10,2 (,/,),1), low temperature coefficient of resistance (,1.191/K) and good thermal stability. This simplified spray technique may be considered as a promising alternative to conventional spray for the massive production of economic SnO2 - ZnO films for solar cells, sensors and opto-electronic applications. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Physical properties of Dy and La doped SnO2 thin films prepared by a cost effective vapour deposition technique

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2006
J. Joseph
Abstract Stannous oxide (SnO2) thin film is one of the most widely used n-type transparent semi-conductor films in electronics, electro-optics and solar energy conversion. By achieving controlled non-stoichiometry, we can get good transparency and high electrical conductivity simultaneously in SnO2 thin films. Dy and La doped SnO2 thin films have been prepared by a cost effective vapour deposition technique. The structural, photo-electronic, optical and electrical properties of the doped and undoped films were studied. The results of X-ray Diffraction studies reveals the polycrystalline nature of the films with preferential orientation along the (101), (211) and (301) planes and their average grain size variation for different deposition temperature. Photoconductivity and Photovoltaic studies of the films were also performed. The optical properties of these films were studied by measuring their optical transmission as a function of wavelength. The optical transmission is found to be increased on Dy doping and decreased on La doping. The band gap, refractive index and thickness of the films were calculated from U-V transmittance and Absorption graphs. The optical band gap of undoped film is found to be 4.08 eV, but on doping it shifts to lower energies and then increases on increasing the concentration of both dopants. Its electrical parameters such as sheet resistance, resistivity, mobility, Hall coefficient, and carrier concentration were determined by Four Probe, Van der Pauw and Hall Probe method. On doping with Dy, carrier conversion takes place from n-type to p-type and p-conductivity dominates. On La doping no carrier conversion takes place but resistivity decreases. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Electrochemical Method for Synthesis of a ZnFe2O4/TiO2 Composite Nanotube Array Modified Electrode with Enhanced Photoelectrochemical Activity

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2010
Yang Hou
Abstract An electrode with intimate and well-aligned ZnFe2O4/TiO2 composite nanotube arrays is prepared via electrochemical anodization of pure titanium foil in fluorine-containing ethylene glycol, followed by a novel cathodic electrodeposition method. The deposition of ZnFe2O4 is promoted in the self-aligned, vertically oriented TiO2 nanotube arrays but minimized at the tube entrances. Thus, pore clogging is prevented. Environmental scanning electron microscopy, energy-dispersive X-ray spectra, high-resolution transmission electron microscopy, X-ray diffraction patterns, and X-ray photoelectron spectroscopy indicate that the as-prepared samples are highly ordered and vertically aligned TiO2 nanotube arrays with ZnFe2O4 nanoparticles loading. The TiO2 nanotubes are anatase with the preferential orientation of <101> plane. Enhanced absorption in both UV and visible light regions is observed for the composite nanotube arrays. The current,voltage curve of ZnFe2O4 -loaded TiO2 nanotube arrays reveals a rectifying behavior. The enhanced separation of photoinduced electrons and holes is demonstrated by surface photovoltage and photocurrent measurements. Meanwhile, the photoelectrochemical investigations verify that the ZnFe2O4/TiO2 composite nanotube array modified electrode has a more effective photoconversion capability than the aligned TiO2 nanotube arrays alone. In addition, the photoelectrocatalytic ability of the novel electrode is found enhanced in the degradation of 4-chlorophenol. [source]


Determination of rock mass strength properties by homogenization

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 13 2001
A. Pouya
Abstract A method for determining fractured rock mass properties is presented here on the basis of homogenization approach. The rock mass is considered to be a heterogeneous medium composed of intact rock and of fractures. Its constitutive model is studied numerically using finite element method and assimilating the fractures to joint elements (Coste, Comportement Thermo-Hydro-Mécanique des massifs rocheux fracturés. Thèse de Doctorat, Ecole Nationale des Ponts et Chaussées, Paris, 1997). The method has been applied to a granite formation in France. Geological data on different families of fractures have been used for the statistical representation of the fractures. A mesh-generating tool for the medium with high density of fractures has been developed. The mechanical behaviour of the rock mass (elasticity, ultimate strength and hardening law) has been determined assuming linear elasticity and Mohr,Coulomb strength criterion both for the intact rock and the fractures. Evolution of the mechanical strength in different directions has been determined as a function of the mean stress, thanks to various numerical simulations. The mechanical strength appears to be anisotropic due to the preferential orientation of the fractures. The numerical results allowed us to determine an oriented strength criterion for the homogenized rock mass. A 2D constitutive law for the homogenized medium has been deduced from numerical data. A 3D extension of this model is also presented. Copyright © 2001 John Wiley & Sons, Ltd. [source]


Macroscopic Fibers of Oriented Vanadium Oxide Ribbons and Their Application as Highly Sensitive Alcohol Microsensors,

ADVANCED MATERIALS, Issue 24 2005
L. Biette
Vanadium oxide macroscopic fibers (see Figure) are obtained by an extrusion process. The fibers consist of nanoscopic ribbons with a preferential orientation and a longitudinal Young's modulus of around 15,GPa. As well as showing high sensitivity, the fibers reversibly cycle between insulating and semiconducting upon exposure to alcohol vapor sources, with signature responses to different alcohols. [source]


Fourier analysis methodology of trabecular orientation measurement in the human tibial epiphysis

JOURNAL OF ANATOMY, Issue 2 2001
M. HERRERA
Methods to quantify trabecular orientation are crucial in order to assess the exact trajectory of trabeculae in anatomical and histological sections. Specific methods for evaluating trabecular orientation include the ,point counting' technique (Whitehouse, 1974), manual tracing of trabecular outlines on a digitising board (Whitehouse, 1980), textural analysis (Veenland et al. 1998), graphic representation of vectors (Shimizu et al. 1993; Kamibayashi et al. 1995) and both mathematical (Geraets, 1998) and fractal analysis (Millard et al. 1998). Optical and computer-assisted methods to detect trabecular orientation of bone using the Fourier transform were introduced by Oxnard (1982) later refined by Kuo & Carter (1991) (see also Oxnard, 1993, for a review), in the analysis of planar sections of vertebral bodies as well as in planar radiographs of cancellous bone in the distal radius (Wigderowitz et al. 1997). At present no studies have applied this technique to 2-D images or to the study of dried bones. We report a universal computer-automated technique for assessing the preferential orientation of the tibial subarticular trabeculae based on Fourier analysis, emphasis being placed on the search for improvements in accuracy over previous methods and applied to large stereoscopic (2-D) fields of anatomical sections of dried human tibiae. Previous studies on the trajectorial architecture of the tibial epiphysis (Takechi, 1977; Maquet, 1984) and research data about trabecular orientation (Kamibayashi et al. 1995) have not employed Fourier analysis. [source]


Preparation of rubber composites from ground tire rubber reinforced with waste-tire fiber through mechanical milling

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007
Xin-Xing Zhang
Abstract Composites made from ground tire rubber (GTR) and waste fiber produced in tire reclamation were prepared by mechanical milling. The effects of the fiber content, pan milling, and fiber orientation on the mechanical properties of the composites were investigated. The results showed that the stress-induced mechanochemical devulcanization of waste rubber and the reinforcement of devulcanized waste rubber with waste-tire fibers could be achieved through comilling. For a comilled system, the tensile strength and elongation at break of revulcanized GTR/fiber composites reached maximum values of 9.6 MPa and 215.9%, respectively, with 5 wt % fiber. Compared with those of a composite prepared in a conventional mixing manner, the mechanical properties were greatly improved by comilling. Oxygen-containing groups on the surface of GTR particles, which were produced during pan milling, increased interfacial interactions between GTR and waste fibers. The fiber-filled composites showed anisotropy in the stress,strain properties because of preferential orientation of the short fibers along the roll-milling direction (longitudinal), and the adhesion between the fiber and rubber matrix was improved by the comilling of the fiber with waste rubber. The proposed process provides an economical and ecologically sound method for tire-rubber recycling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4087,4094, 2007 [source]


Hot Forging of a Textured ,-Sialon Ceramic

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2006
Andrew Carman
A texture was introduced into an Sm-,-sialon ceramic by hot pressing, such that the c -axis was preferentially oriented normal to the pressing direction. The material was then uniaxially hot forged for up to 60 min, with the forging direction normal to the hot-pressing direction. The texture initially reduced to a one-dimensional preferential orientation in the direction normal to both the hot-pressing and hot-forging directions. Further deformation resulted in a two-dimensional texture normal to the hot-forging direction. The forging process was used to produce a strong one-dimensional texture by alternating between the hot-pressing and hot-forging directions, thereby producing a material with significant anisotropy in its properties. [source]


High-Silica Ferrierite Zeolite Self-Transformed from Aluminosilicate Gel

CHEMPHYSCHEM, Issue 6 2006
Xiaowei Cheng Dr.
Perfectly built zeolites: Ferrierite (FER) zeolite, with the perfect crystal structure and the same preferential orientation as siliceous FER zeolite, is synthesized by the self transformation of the amorphous seeded dry gel with a novel vapor phase transport (VPT) method in the mixed vapor of tetrahydrofuran and water. [source]


Synsedimentary tensional features in Upper Triassic shallow-water platform carbonates of the Carnian Prealps (northern Italy) and their importance as palaeostress indicators

BASIN RESEARCH, Issue 2 2000
Cozzi
The extensive shallow-water carbonate platform deposits of the Dolomia Principale Formation (Southern Alps, northern Italy) accumulated during the Late Triassic, a time of plate-scale reorganization and rifting. Synsedimentary tensional features such as fractures, neptunian dykes, normal faults, shatter breccias and laterally discordant intraformational breccias have been studied within a well-preserved platform-to-basin transition in the Monte Pramaggiore area (Carnian Prealps). These tensional features follow three preferential orientations: N,S, E,W and NE,SW. To fully explain these different arrays it is proposed that the study area experienced during the Late Triassic the waning rifting phase connected to the westward propagation of the NeoTethys (N,S extension) and the onset of the rifting phase that led in the Middle Jurassic to the opening of the Central Atlantic (E,W extension), with a contemporaneous reactivation of Early,Middle Triassic NE,SW-orientated faults. This palaeostress analysis reveals the good potential of tensional features as reliable palaeostress indicators. [source]