scholarly journals Manual measurement of angles in backscattered and transmission Kikuchi diffraction patterns

2020 ◽  
Vol 53 (2) ◽  
pp. 435-443
Author(s):  
Gert Nolze ◽  
Tomasz Tokarski ◽  
Grzegorz Cios ◽  
Aimo Winkelmann

A historical tool for crystallographic analysis is provided by the Hilton net, which can be used for manually surveying the crystal lattice as it is manifested by the Kikuchi bands in a gnomonic projection. For a quantitative analysis using the Hilton net, the projection centre as the relative position of the signal source with respect to the detector plane needs to be known. Interplanar angles are accessible with a precision and accuracy which is estimated to be ≤0.3°. Angles between any directions, e.g. zone axes, are directly readable. Finally, for the rare case of an unknown projection-centre position, its determination is demonstrated by adapting an old approach developed for photogrammetric applications. It requires the indexing of four zone axes [uvw] i in a backscattered Kikuchi diffraction pattern of a known phase collected under comparable geometric conditions.

Author(s):  
Fuming Chu ◽  
D. P. Pope ◽  
D. S. Zhou ◽  
T. E. Mitchell

A C15 Laves phase, HfV2+Nb, shows promising mechanical properties and here we describe the structure of its grain boundaries. The C15 Laves phase has a fcc lattice with a=7.4Å. An alloy of composition Hf14V64Nb22 (including a C15 matrix and a second phase of V-rich bcc solution) was made by arc-melting. The alloy was homogenized at 1200°C for 120h. Preliminary study concentrated on Σ3{<110>/70.53°} grain boundaries in the C15 phase using Philips 400T and CM 30 microscopes.The most-commonly observed morphology of Σ3{<110>/70.53°} grain boundaries in the C15 phase is a faceted boundary. A bright field image (BFI) of the faceted boundary and the corresponding diffraction patterns with the grain boundary edge-on are shown in Fig. 1(a). From the diffraction patterns using a <110> zone axis for both grains, it is obvious that this is a Σ3{<110>/70.53°} grain boundary. Crystallographic analysis shows that the Σ3{<110>/70.53°} grain boundaries selectively facet with the following relationships between the two grains: {111}1//{111}2, {112}1//{112}2, {111}1//{115}2, and {001}1//{221}2.


Author(s):  
Sajal Biring

Abstract The FinFET has been introduced in the last decade to provide better transistor performance as the device size shrinks. The performance of FinFET is highly sensitive to the size and shape of the fin, which needs to be optimized with tighter control. Manual measurement of nano-scale features on TEM images of FinFET is not only a time consuming and tedious task, but also prone to error owing to visual judgment. Here, an auto-metrology approach is presented to extract the measured values with higher precision and accuracy so that the uncertainty in the manual measurement can be minimized. Firstly, a FinFET TEM image is processed through an edge detecting algorithm to reveal the fin profile precisely. Finally, an algorithm is utilized to calculate out the required geometrical data relevant to the FinFET parameters and summarizes them to a table or plots a graph based on the purpose of data interpretation. This auto-metrology approach is expected to be adopted by academia and/or industry for proper data analysis and interpretation with higher precision and efficiency.


Clay Minerals ◽  
1982 ◽  
Vol 17 (4) ◽  
pp. 393-399
Author(s):  
C. E. Corbato ◽  
R. T. Tettenhorst

AbstractQuantitative estimates were made by visually matching computer-simulated with experimental X-ray powder diffractometer patterns for two samples. One was a natural mixture of dickite and nacrite in about equal proportions. The second sample contained mostly quartz with corundum and mullite in small (0.5–1%) amounts. Percentages deduced from pattern matching agreed to within ±10% of the weight fractions of the components determined by an alternative method of analysis.


2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Jairo Roa-Rojas

We report structural analysis, surface morphology, magnetic ordering, dielectric response, optical feature and the electronic structure of the Dy2BiFeO6 novel complex perovskite. The samples were produced by the standard solid-state reaction recipe. Crystallographic analysis was performed by Rietveld refinement of experimental X-ray diffraction patterns. Results show that this material crystallizes in a perovskite with orthorhombic structure, which corresponds to the Pnma (#62) space group. From the Curie-Weiss fitting on the curve of susceptibility as a function of temperature we establish that the ordering corresponds to a paramagnetic-antiferromagnetic transition, with a Weiss temperature q=-18,5 K, which is compatible with the behavior of the inverse of susceptibility as a function of temperature, and a Néel temperatura TN=50,8 K. The Curie constant allowed for us to obtain an effective magnetic moment of 15,7 mB. The result of magnetization as a function of the applied field, measured at T=50 K, shows a magnetic hysteresis behavior that corroborate the magnetic ordering present for this temperature value. Measurements of the dielectric constant as a function of applied frequencies at room temperature give as a result a high relative dielectric constant (e=780). The reflectance curve as a function of the wavelength reveals the typical behavior of a double perovskite-like material and permits to obtain the energy gap 2,74 eV, which is characteristic of a semiconductor material.


2015 ◽  
Vol 48 (3) ◽  
pp. 797-813 ◽  
Author(s):  
Farangis Ram ◽  
Stefan Zaefferer ◽  
Tom Jäpel ◽  
Dierk Raabe

The fidelity – that is, the error, precision and accuracy – of the crystallographic orientations and disorientations obtained by the classical two-dimensional Hough-transform-based analysis of electron backscatter diffraction patterns (EBSPs) is studied. Using EBSPs simulated based on the dynamical electron diffraction theory, the fidelity analysis that has been previously performed using the patterns simulated based on the theory of kinematic electron diffraction is improved. Using the same patterns, the efficacy of a Fisher-distribution-based analytical accuracy measure for orientation and disorientation is verified.


1995 ◽  
Vol 410 ◽  
Author(s):  
Bogdan Palosz ◽  
Svetlana Stel'makh ◽  
Stanislaw Gierlotka

ABSTRACTA method of analysis of disordering in α- and β-SiC polycrystals by numerical modeling, and a simulation of X-ray diffraction profiles are presented. The diffraction patterns of nonperiodic structures were simulated for models of 2000 layer fragments of the structure. Computer generation of the models was based on the Poisson function describing the size distribution of the domains of basic polytypes and faults. The models were quantified by a set of input probability parameters describing relative frequencies of the occurrence of the domains of polytypes and faults. Implementation of a correlation parameter that characterizes coherence of sequential domains of a given polytype assures a good reproducibility of the simulated diffraction profiles obtained for the same set of the model parameters. Based on this method, a quantitative analysis of disordering in polycrystals of SiC annealed in the temperature range 1100–2200 °C was performed.


1973 ◽  
Vol 38 (3) ◽  
pp. 339-344 ◽  
Author(s):  
John W. Weymouth

AbstractThis is a preliminary report on a quantitative method for grouping prehistoric pottery using x-ray diffraction techniques. Of the various analytical methods that have been applied to the analysis of pottery, x-ray diffraction techniques have been among the least used, and then usually to obtain qualitative information. Most analytic methods measure the relative abundance of chemical elements, but diffraction patterns give information on the crystalline substances in the pottery. In this study, attention is directed to the crystalline components of the temper rather than the clays or their derivatives. The method groups pottery according to the relative concentrations of such minerals as quartz, calcite, and the feldspars. Thus, success depends on reasonable consistency in the use of tempering materials by pottery makers at one time and place. I have examined a number of sherds from different sites in Iowa and Missouri supplied by Dale R. Henning, University of Nebraska. The results so far indicate that it is possible to group prehistoric pottery by a quantitative analysis of the x-ray diffraction pattern of the temper in the pottery.


Author(s):  
L. L. Degn

The crotoxin complex is a 24,500 dalton neurotoxic protein isolated from the venom of the Brazilian rattlesnake Crotalus durissus terrificus. The crotoxin complex crystallizes as thin crystals suitable for high resolution 3-D reconstruction by electron crystallographic analysis. High resolution imaging of an untilted crotoxin complex crystal embedded in glucose has been reported. Presented here is high resolution (3.9 Å) imaging of an untilted crotoxin complex crystal embedded in vitreous ice.Several technical problems are involved in the collection of high resolution electron crystallographic data for 3-D reconstruction. First, the specimen should be as flat as possible on the grid since bending due to specimen preparation or due to beam-induced movement may cause smeared reflections in electron diffraction patterns or optical diffractograms, a phenomenon that is particularly noticeable in highly tilted specimens.


Sign in / Sign up

Export Citation Format

Share Document