Orientation Relationships and Interfaces Between Low Symmetry Phases in The Yttria-Alumina System

1994 ◽  
Vol 357 ◽  
Author(s):  
R. S. Hay
Keyword(s):  
Monoclinic Phase ◽  
Three Dimensional ◽  
Real Space ◽  
Reciprocal Space ◽  
High Symmetry ◽  
Orientation Relationships ◽  
Yttrium Aluminum ◽  
High Resolution Tem ◽  
Interphase Boundaries ◽  
Definition Of

AbstractInterphase boundaries and orientation relationships for yttria - yttrium-aluminum monoclinic and yttrium-aluminum monoclinic - yttrium-aluminum perovskite eutectics were observed by standard and high resolution TEM techniques. Three and five orientation relationships were found for each system, respectively. These eutectics all had a monoclinic phase and therefore had little potential for high symmetry overlap. In many cases low index planes with similer spacings or spacing multiples were parallel. However, presence of a monoclinic phase made definition of a three-dimensional low index near-CSL very difficult, so a combination of planes corresponding to reciprocal-space directions and zones corresponding to real-space directions were often needed for a geometric description of the orientation relationship. In general, two planes and the real-space direction corresponding to the zone for these planes described the orientation relationships. The disregistry between reciprocal-space coincidence sites was not localized by dislocations large enough to be visible.

scholarly journals 6D electron microscopy: combining real-space and reciprocal-space tomography

2014 ◽  
Vol 70 (a1) ◽  
pp. C368-C368 ◽  
Author(s):  
Alexander Eggeman ◽  
Robert Krakow ◽  
Paul Midgley
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Real Space ◽  
Dark Field ◽  
Reciprocal Space ◽  
Data Set ◽  
Wide Range ◽  
The Matrix ◽  
Precession Electron Diffraction ◽  
Tilt Series

STEM and TEM-based tomography has been used widely to study the 3D morphology of a wide range of materials. Similarly reciprocal space tomography in which a tilt-series of diffraction patterns are acquired offers a powerful method for the analysis of the atomic structure of crystalline materials. The natural progression is to combine these techniques into a complete three dimensional morphology and crystallography data set, allowing both features to be studied simultaneously. Using a tilt series of scanning precession electron diffraction measurements from a commercially available Ni-base superalloy as an example, the complete reciprocal lattice orientation for a number of components embedded within the matrix could be determined. It was straightforward to identify reciprocal lattice vectors that allowed dark-field images representing each phase to be produced post-acquisition. In turn these were combined using geometric tomography methods to yield a 3-D tomogram of the superalloy. Imaging these phases using conventional ADF STEM tomography would potentially be challenging given the compositional similarity between the different phases. From the combined dataset the spatial distribution of the component phases could be easily recovered but more importantly the orientational relationships between these different components could be unambiguously determined. In this way the thermo-mechanical history of the sample could be inferred from the arrangement of coherent and semi-coherent interfaces and a previously unreported crystallographic registry between metal carbide (MC) and the matrix f.c.c. phases could been identified. The possibilities for development and applications of this technique will be discussed further.

Transmission electron microscopy of C70 single crystals at room temperature

1992 ◽  
Vol 7 (9) ◽  
pp. 2440-2446 ◽  
Author(s):  
Vinayak P. Dravid ◽  
Xiwei Lin ◽  
Hong Zhang ◽  
Shengzhong Liu ◽  
Manfred M. Kappes
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Three Dimensional ◽  
Real Space ◽  
Acceptable Error ◽  
Hexagonal Close Packed ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Hcp Structure

Transmission electron microscopy (TEM) techniques have been employed to study the room temperature solid state form of chromatographically purified C70. Tilting and electron diffraction experiments in three-dimensional reciprocal space, on samples prepared by crystallization from several different solvents, show that C70 crystallites adopt hexagonal close packed (hcp) structure with a = 1.01 ± 0.05 nm and c = 1.70 ± 0.08 nm. The extinctions and observed reflections conform to the P63/mmc space group. High resolution TEM images reveal the molecular order and periodicity associated with C70 crystallites in real space. The experimental results are in agreement with the preliminary computations of crystal structure within acceptable error limits.

Imaging of strain and lattice orientation by quick scanning X-ray microscopy combined with three-dimensional reciprocal space mapping

2014 ◽  
Vol 47 (2) ◽  
pp. 762-769 ◽  
Author(s):  
Gilbert André Chahine ◽  
Marie-Ingrid Richard ◽  
Roberto Arturo Homs-Regojo ◽  
Thu Nhi Tran-Caliste ◽  
Dina Carbone ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Continuous Mapping ◽  
Real Space ◽  
Reciprocal Space ◽  
Data Sets ◽  
Two Dimensional ◽  
Reciprocal Space Mapping ◽  
X Ray ◽  
Study Materials ◽  
User Friendly

Numerous imaging methods have been developed over recent years in order to study materials at the nanoscale. Within this context, scanning X-ray diffraction microscopy has become a routine technique, giving access to structural properties with sub-micrometre resolution. This article presents an optimized technique and an associated software package which have been implemented at the ID01 beamline (ESRF, Grenoble). A structural scanning probe microscope with intriguing imaging qualities is obtained. The technique consists in a two-dimensional quick continuous mapping with sub-micrometre resolution of a sample at a given reciprocal space position. These real space maps are made by continuously moving the sample while recording scattering images with a fast two-dimensional detector for every point along a rocking curve. Five-dimensional data sets are then produced, consisting of millions of detector images. The images are processed by the user-friendly X-ray strain orientation calculation software (XSOCS), which has been developed at ID01 for automatic analysis. It separates tilt and strain and generates two-dimensional maps of these parameters. At spatial resolutions of typically 200–800 nm, this quick imaging technique achieves strain sensitivity below Δa/a= 10−5and a resolution of tilt variations down to 10−3° over a field of view of 100 × 100 µm.

Local Metrics for Rigid Body Displacements

2004 ◽  
Vol 126 (5) ◽  
pp. 805-812 ◽  
Author(s):  
Johannes K. Eberharter ◽  
Bahram Ravani
Keyword(s):  
Rigid Body ◽  
Projective Space ◽  
Affine Space ◽  
Three Dimensional ◽  
Real Space ◽  
Elegant Method ◽  
Rigid Body Displacement ◽  
Definition Of ◽  
Three Space ◽  
Motion Design

One hundred years ago, Eduard Study introduced a very elegant method to describe a rigid body displacement in three-space. He mapped each position of a rigid body onto a point on a quadric, now called the Study quadric. This quadric is a six-dimensional rational hyper-surface, embedded in a seven-dimensional projective real space, called Study’s soma space. More than half a century later Ravani and Roth reconfigured Study’s soma space into a three-dimensional dual projective space, and defined a geometric metric for rigid body displacements. Here, approximately 20 years later, we again use Study’s quadric and define a new metric for rigid body displacements based on an optimized local mapping of the quadric. The local mappings of the quadric are achieved using stereographic projections, resulting in an affine space where the Euclidean definition of a metric can be used for rigid body displacements and techniques from design of curves and surfaces can be directly utilized for motion design. The results are illustrated by examples.

Envelope skeletonization as a means to determine monomer masks and non-crystallographic symmetry relationships: application in the solution of the structure of fibrinogen fragment D

1999 ◽  
Vol 55 (2) ◽  
pp. 458-463 ◽  
Author(s):  
Glen Spraggon
Keyword(s):  
Three Dimensional ◽  
Real Space ◽  
Reciprocal Space ◽  
Structure Solution ◽  
Crystallographic Symmetry ◽  
Translation Component ◽  
Rotation Function ◽  
Molecular Envelope

An algorithm is described which utilizes the solvent mask generated by the solvent-flattening technique to calculate a monomer molecular envelope. In the case where non-crystallographic symmetry (NCS) is present in the crystal and self-rotation angles are known from a self-rotation function, the resultant monomer envelopes can be used to search for the translation component of the NCS element by a three-dimensional search in real space. In the absence of self-rotation angles, the monomer envelope may be used to derive the NCS operators by reciprocal-space techniques. Thus, an automatic procedure for averaging directly from the solvent-flattening stage can be implemented. The procedure was instrumental in the structure solution of fibrinogen fragment D, which is presented as an example.

An Image Reconstruction System Applied to High Voltage Microscopy

1975 ◽  
Vol 33 ◽  
pp. 292-293
Author(s):  
D. E. Johnson
Keyword(s):  
High Voltage ◽  
Prior Information ◽  
Block Diagram ◽  
Three Dimensional ◽  
Real Space ◽  
Two Dimensional ◽  
Efficient Manner ◽  
Fourier Methods ◽  
Tilt Series ◽  
Methods Of Reconstruction

Increased specimen penetration; the principle advantage of high voltage microscopy, is accompanied by an increased need to utilize information on three dimensional specimen structure available in the form of two dimensional projections (i.e. micrographs). We are engaged in a program to develop methods which allow the maximum use of information contained in a through tilt series of micrographs to determine three dimensional speciman structure.In general, we are dealing with structures lacking in symmetry and with projections available from only a limited span of angles (±60°). For these reasons, we must make maximum use of any prior information available about the specimen. To do this in the most efficient manner, we have concentrated on iterative, real space methods rather than Fourier methods of reconstruction. The particular iterative algorithm we have developed is given in detail in ref. 3. A block diagram of the complete reconstruction system is shown in fig. 1.

Use of 2½ D imaging in analysis of NiTi martensite

1978 ◽  
Vol 36 (1) ◽  
pp. 610-611
Author(s):  
G. M. Michal
Keyword(s):  
Memory Effect ◽  
Monoclinic Phase ◽  
Reaction Path ◽  
Structural Characteristics ◽  
Salient Feature ◽  
Martensite Phase ◽  
Orientation Relationships ◽  
Low Symmetry ◽  
Hydride Phases ◽  
Unusual Shape

Several TEM investigations have attempted to correlate the structural characteristics to the unusual shape memory effect in NiTi, the consensus being the essence of the memory effect is ostensible manifest in the structure of NiTi transforming martensitic- ally from a B2 ordered lattice to a low temperature monoclinic phase. Commensurate with the low symmetry of the martensite phase, many variants may form from the B2 lattice explaining the very complex transformed microstructure. The microstructure may also be complicated by the enhanced formation of oxide or hydride phases and precipitation of intermetallic compounds by electron beam exposure. Variants are typically found in selfaccommodation groups with members of a group internally twinned and the twins themselves are often observed to be internally twinned. Often the most salient feature of a group of variants is their close clustering around a given orientation. Analysis of such orientation relationships may be a key to determining the nature of the reaction path that gives the transformation its apparently perfect reversibility.

Systematic zone-Axis orientation of NM-scale particles for microdiffraction

1990 ◽  
Vol 48 (4) ◽  
pp. 262-263
Author(s):  
E D Boyes ◽  
L Hanna
Keyword(s):  
Real Space ◽  
Dark Field ◽  
Zone Axis ◽  
High Symmetry ◽  
Lattice Imaging ◽  
Cell Level ◽  
Bright Field ◽  
Axis Orientation ◽  
Annular Dark Field ◽  
Target Designation

A VG HB501 FEG STEM has been modified to provide track whilst tilt [TWIT] facilities for controllably tilting selected and initially randomly aligned nanometer-sized particles into the high symmetry zone-axis orientations required for microdiffraction, lattice imaging and chemical microanalysis at the unit cell level. New electronics display in alternate TV fields and effectively in parallel on split [+VTR] or adjacent externally synchronized screens, the micro-diffraction pattern from a selected area down to <1nm2 in size, together with the bright field and high angle annular dark field [HADF] STEM images of a much wider [˜1μm] area centered on the same spot. The new system makes it possible to tilt each selected and initially randomly aligned small particle into a zone axis orientation for microdiffraction, or away from it to minimize orientation effects in chemical microanalysis. Tracking of the inevitable specimen movement with tilt is controlled by the operator, with realtime [60Hz] update of the target designation in real space and the diffraction data in reciprocal space. The spot mode micro-DP and images of the surrounding area are displayed continuously. The regular motorized goniometer stage for the HB501STEM is a top entry design but the new control facilities are almost equivalent to having a stage which is eucentric with nanometric precision about both tilt axes.

Application of high-resolution field-emission LVSEM, backscatter imaging, immunogold staining to definition of the spatial distributions of two human neutrophil adherence receptors

1993 ◽  
Vol 51 ◽  
pp. 36-37
Author(s):  
Robert D. Nelson ◽  
Sharon R. Hasslen ◽  
Stanley L. Erlandsen
Keyword(s):  
Cell Surface ◽  
Surface Membrane ◽  
Three Dimensional ◽  
Human Neutrophils ◽  
Spatial Distributions ◽  
Immunogold Staining ◽  
Functional Control ◽  
Neutrophil Adherence ◽  
Definition Of ◽  
Mode Of Attachment

Receptors are commonly defined in terms of number per cell, affinity for ligand, chemical structure, mode of attachment to the cell surface, and mechanism of signal transduction. We propose to show that knowledge of spatial distribution of receptors on the cell surface can provide additional clues to their function and components of functional control.L-selectin and Mac-1 denote two receptor populations on the neutrophil surface that mediate neutrophil-endothelial cell adherence interactions and provide for targeting of neutrophil recruitment to sites of inflammation. We have studied the spatial distributions of these receptors using LVSEM and backscatter imaging of isolated human neutrophils stained with mouse anti-receptor (primary) antibody and goat anti-mouse (secondary) antibody conjugated to 12 nm colloidal gold. This combination of techniques provides for three-dimensional analysis of the expression of these receptors on different surface membrane domains of the neutrophil: the ruffles and microvilli that project from the cell surface, and the cell body between these projecting structures.

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