HREM Studies of Structural Changes Induced by Phase Transformations in Zirconia Powders

1990 ◽  
Vol 48 (1) ◽  
pp. 24-25
Author(s):  
M.G. Blanchin ◽  
G. Nihoul ◽  
E. Bernstein
Keyword(s):  
Electron Microscopy ◽  
Phase Transformations ◽  
Structural Changes ◽  
Dark Field ◽  
Powder Materials ◽  
Aggregation State ◽  
Dark Field Imaging ◽  
High Resolution Tem ◽  
Hydrated Zirconium ◽  
Zirconia Powders

The use of microcrystalline (submicron) and nanocrystalline (≤10nm) particles as powder materials for sintering of advanced ceramics like oxide-based ceramics or high-Tc superconductors , requires new techniques for characterization. Thus classical optical microscopy or even scanning electron microscopy are no longer effective for examination of 1-10 nm particles. In previous work we developed quantitative analysis of transmission electron microscopy (TEM) observations at medium resolution (0.4-1 nm, typically) to study morphology, size distribution, agglomeration and/or aggregation state of elementary powder particles characterized by bright- and dark - field imaging as well as diffraction TEM techniques.Here the high resolution TEM (HREM) techniques (at 200 kV) have been used to investigate phase transformations occuring in ultrafine zirconia powders processed by calcination of an amorphous hydrated zirconium oxide prepared at low temperature. X-ray examination showed the sequence : amorphous , cubic (C) or tetragonal (T) , monoclinic (M), at increasing temperatures.

Techniques for Characterising Artificial Layer Structures using Transmission Electron Microscopy

1987 ◽  
Vol 103 ◽  
Author(s):  
W. M. Stobbs
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Changes ◽  
Dark Field ◽  
Multilayer Structures ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Layer Structures ◽  
Quantitative Characterisation ◽  
Field Imaging

ABSTRACTT.E.M. methods are described for the quantitative characterisation of the compositional and structural changes at interfaces and in homo- and hetero-phase multilayer structures. Many of the newer approaches described including the Fresnel and Centre Stop Dark Field Imaging Methods were developed specifically for such characterisations. The range of applications of each of the techniques is assessed as is the importance of delineating the limiting effects of inelastic and inelastic/elastic multiple scattering.

Imaging of III-V Compound Superlattices by Hrem and Rem

1986 ◽  
Vol 77 ◽  
Author(s):  
B. C. De Cooman ◽  
J. R. Conner ◽  
S. R. Summerfelt ◽  
S. McKernan ◽  
C. B. Carter ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Dark Field ◽  
Contrast Effects ◽  
Cross Sectional ◽  
Dark Field Imaging ◽  
Thin Foils ◽  
High Resolution Tem ◽  
Reflection Electron Microscopy ◽  
Field Imaging

ABSTRACTTwo techniques for the analysis of III-V compound superlattices are examined. It has been proposed that high-resolution TEM of [100]-oriented thin foils would give an improvement in layer contrast compared with [110]-oriented thin foils; it is shown here that the contrast of [100]-oriented superlattices is not necessarily better. Moreover, both high resolution and conventional dark-field imaging may be subject to significant diffraction contrast effects resulting from the bending of the reflecting planes near the surface of the sample. Reflection electron microscopy (REM) of cross-sectional (110) cleavage planes can also yield dark-field superlattice images and selected area RHEED patterns can in principle be used to determine reliably the superlattice strain as surface effects are minimized.

A Preparation of High Resolution Standards for Electron Microscopy. Part II

1971 ◽  
Vol 29 ◽  
pp. 160-161
Author(s):  
Akira Tanaka ◽  
David F. Harling
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Carbon Black ◽  
Single Crystal ◽  
Dark Field ◽  
Graphitized Carbon Black ◽  
Graphitized Carbon ◽  
Dark Field Imaging ◽  
Crystal Films ◽  
Micro Holes

In the previous paper, the author reported on a technique for preparing vapor-deposited single crystal films as high resolution standards for electron microscopy. The present paper is intended to describe the preparation of several high resolution standards for dark field microscopy and also to mention some results obtained from these studies. Three preparations were used initially: 1.) Graphitized carbon black, 2.) Epitaxially grown particles of different metals prepared by vapor deposition, and 3.) Particles grown epitaxially on the edge of micro-holes formed in a gold single crystal film.The authors successfully obtained dark field micrographs demonstrating the 3.4Å lattice spacing of graphitized carbon black and the Au single crystal (111) lattice of 2.35Å. The latter spacing is especially suitable for dark field imaging because of its preparation, as in 3.), above. After the deposited film of Au (001) orientation is prepared at 400°C the substrate temperature is raised, resulting in the formation of many square micro-holes caused by partial evaporation of the Au film.

A Transmission Electron Microscopical Investigation of Phase Transformations in TiNi

1980 ◽  
Vol 38 ◽  
pp. 340-341
Author(s):  
P. Moine ◽  
G. M. Michal ◽  
R. Sinclair
Keyword(s):  
Electron Microscopy ◽  
Phase Transformations ◽  
Applied Stress ◽  
Structural Changes ◽  
Microscopical Investigation ◽  
Temperature Range ◽  
Transmission Electron ◽  
Electron Microscopical ◽  
Diffraction Effects ◽  
Microscopy Images

Premartensitic effects in near equiatomic TiNi have been pointed out by several authors(1-5). These include anomalous contrast in electron microscopy images (mottling, striations, etc. ),diffraction effects(diffuse streaks, extra reflections, etc.), a resistivity peak above Ms (temperature at which a perceptible amount of martensite is formed without applied stress). However the structural changes occuring in this temperature range are not well understood. The purpose of this study is to clarify these phenomena.

scholarly journals Annular Dark Field Imaging of Catalyst Nanoparticles in Single Shot Dynamic Transmission Electron Microscopy

2009 ◽  
Vol 15 (S2) ◽  
pp. 1082-1083
Author(s):  
D Masiel ◽  
B Reed ◽  
T LaGrange ◽  
ND Browning
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dark Field ◽  
Single Shot ◽  
Catalyst Nanoparticles ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Annular Dark Field ◽  
Field Imaging

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

scholarly journals Method combining BAC film and positive staining for the characterization of DNA intermediates by dark-field electron microscopy

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Yann Benureau ◽  
Eliana Moreira Tavares ◽  
Ali-Akbar Muhammad ◽  
Sonia Baconnais ◽  
Eric Le Cam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Dark Field ◽  
In Vitro Assays ◽  
Positive Staining ◽  
Synthetic Dna ◽  
Dark Field Imaging ◽  
Alkyl Ammonium

Abstract DNA intermediate structures are formed in all major pathways of DNA metabolism. Transmission electron microscopy (TEM) is a tool of choice to study their choreography and has led to major advances in the understanding of these mechanisms, particularly those of homologous recombination (HR) and replication. In this article, we describe specific TEM procedures dedicated to the structural characterization of DNA intermediates formed during these processes. These particular DNA species contain single-stranded DNA regions and/or branched structures, which require controlling both the DNA molecules spreading and their staining for subsequent visualization using dark-field imaging mode. Combining BAC (benzyl dimethyl alkyl ammonium chloride) film hyperphase with positive staining and dark-field TEM allows characterizing synthetic DNA substrates, joint molecules formed during not only in vitro assays mimicking HR, but also in vivo DNA intermediates.

Study on Nanometer Size Structures in the Cr-Mo Electroplated Layer Using Transmission Electron Microscopy and Positron Lifetime Measurement

2011 ◽  
Vol 675-677 ◽  
pp. 247-250 ◽  
Author(s):  
Yoshio Tanita ◽  
Daiji Matsui ◽  
Hiroshi Fukushima
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dark Field Image ◽  
Dark Field ◽  
High Density ◽  
Positron Annihilation Lifetime ◽  
Small Crystal ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Crystal Grains

Micro- and nano-structures of the Cr-Mo electroplated layers were studied mainly by Transmission Electron Microscopy (TEM), High Resolution TEM (HRTEM) and Positron Annihilation Lifetime Spectroscopy (PALS). These electroplated layers which were deposited in Cr-Mo electrolyte containing an organic sulfonic acid, showed surface structures having severe ups and downs of small crystal grains. Both selected area diffraction and dark-field image of TEM confirmed the presence of very small crystal grains of less than 50 nm. These small crystal grains exhibited textured structure when the electrolyte contained an organic sulfonic catalyst. PALS results indicated the presence of high density nano-size voids, and HRTEM analysis confirmed the presence of high density voids of 1 nm to 2 nm in diameter. Size and density of these nano-voids increased with the amount of catalyst in the electrolyte.

scholarly journals The origin of striation in the metastable β phase of titanium alloys observed by transmission electron microscopy

2017 ◽  
Vol 50 (3) ◽  
pp. 795-804 ◽  
Author(s):  
Jiangkun Fan ◽  
Jinshan Li ◽  
Yudong Zhang ◽  
Hongchao Kou ◽  
Jaafar Ghanbaja ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dark Field ◽  
Atomic Scale ◽  
Intermediate Structure ◽  
Atomic Displacements ◽  
Β Phase ◽  
Transmission Electron ◽  
Modulated Structures ◽  
High Resolution Tem

For the β phase of Ti-5553-type metastable β-Ti alloys, striations in transmission electron microscopy (TEM) bright- and dark-field images have been frequently observed but their origin has not been sufficiently investigated. In the present work, this phenomenon is studied in depth from the macroscopic scale by neutron diffraction to the atomic scale by high-resolution TEM. The results reveal that the β phase contains homogeneously distributed modulated structures, intermediate between that of the β phase (cubic) and that of the α phase or the ω phase (hexagonal), giving rise to the appearance of additional diffraction spots at 1/2, 1/3 and 2/3 β diffraction positions. The intermediate structure between β and α is formed by the atomic displacements on each second {110}βplane in the \langle 1{\overline 1}0\rangle_{\beta} direction, whereas that between β and ω is formed by atomic displacements on each second and third {112}βplane in the opposite \langle 11{\overline 1}\rangle_{\beta } direction. Because of these atomic displacements, the {110}βand {112}βplanes become faulted, resulting in the streaking of β diffraction spots and the formation of extinction fringes in TEM bright- and dark-field images, the commonly observed striations. The present work reveals the origin of the striations and the intrinsic correlation with the additional electron reflections of the β phase.

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