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Intensity I (intensity + i)
Selected AbstractsSmall-angle neutron scattering investigation of plastically deformed stainless steelJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003Vassily Lebedev The microstuctural evolution of plastically deformed steels has been studied by small-angle neutron scattering at ambient temperature in the range of momentum transfer q = (4,/,)sin(,/2) = 0.01,5 nm,1 where , is neutron wavelength and , is the scattering angle. Samples of austenite stainless steels were pulled on a standard bench to cause a plastic deformation, S = 0,60%, up to the fracture of the material. As a result of the deformation an increase of an order of magnitude was observed in the scatterred intensity I(q)~1/[1+(qRC)2](6- Ds)/2. The analysis of the I(q) distribution has shown the surface fractal nature of the observed nano-scale structures. The evolution of internal surface via intensive growth of pores (size RC~20,40 nm) was found and a linear decrease of the surface fractal dimension 2.9,Ds(S),2.1 was observed. These findings can be used to design the fracture criteria for materials of industrial application. [source] The small-angle scattering structure functions of the single tetrahedronJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003W. Gille Basic properties of the SAS correlation function , (r) and related functions are represented for a tetrahedron of edge length a. An interval splitting into four basic r -intervals in a sequence of cases for averaging the intersection volume between two tetrahedrons has been performed. Remarkably simple analytic expressions result in the first r -interval. Indeed, ,(r) is a polynomial of degree three. The coefficients are given explicitly. The asymptotic expansion I(h) is compared with the exact scattering intensity I(h). [source] Energy structure and micromechanism of photo-electromotive force effect in V-doped CdTe crystalsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2007Yu. P. Gnatenko Abstract For the first time photo-electromotive force (photo-EMF) measurements were carried out for CdTe crystals doped with V atoms as a result of the photogeneration of carriers from deep impurity centers to the conduction band. Tilted geometry was applied that allowed two-dimensional monitoring of the vi- bration source. The CdTe:V crystals were excited by a He,Ne laser with a wavelength of 1.15 ,m (,, = 1.08 eV) and P = 2 mW. The mechanism of the appearance of the holographic current in the CdTe:V crystals taking into account real defect structure was proposed. The frequency dependence of the ac photo-EMF (holographic) current for the CdTe:V crystals was measured. It was shown that a low cut-off frequency for a laser intensity I = 0.2 mW/mm2 equals 6.0 kHz, which corresponds to a response time of 26 ,s. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] X-ray study and structure simulation of amorphous tungsten oxideACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2002L. A. Lugovskaya In this work, X-ray studies of the amorphous oxide films obtained by thermal evaporation of WO3 powder in a vacuum and by anodic oxidation were carried out. X-ray diffraction patterns were obtained in the symmetric reflection geometry on a DRON-4 diffractometer (Mo K, radiation, LiF monochromator) in automatic mode. Molecular dynamics simulation of amorphous tungsten oxide atomic configurations has been carried out in the micro-canonical ensemble (NVE) for N,=,208 atoms and N,=,624 atoms, in a cubic cell, using pairwise Born,Mayer interaction potentials and periodic boundary conditions. One of the purposes of the present work is to analyze the influence of the parameters and the cutoff of the interaction potentials on the interatomic distances. The values obtained in the molecular dynamics simulation for the pair functions D(r) are compared with the experimental data for amorphous oxides in order to choose the most convenient aforesaid values. The values of the average interatomic distances and the coordination numbers obtained by both methods are also compared. The result shows that the tungsten subsystem can be well reproduced using the potential cutoff radius of about 4,Å, but the oxygen subsystem can be well reproduced when the cutoff of the potential for the W,O pairs is equal to 2.8,Å. The configuration built during the molecular dynamics experiment consists of distorted octahedra. These octahedra form chains, as in the WO3 phases of type ReO3, and hexagonal rings, of the same type as in the WO3(1/3)H2O phase, when we extract (1/3)O at every WO3 unit. The pair function D(r) and scattering intensity I(s) distribution curves calculated for simulation configurations show a satisfactory agreement with experiment. [source] | ||||||||||