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 Buried Si and Si:Ge Surface Structure Under Amorphous Ge Films by Plan View Transmission Electron Microscopy

1994 ◽  
Vol 332 ◽  
Author(s):  
Olof C. Hellman
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Shift ◽  
Room Temperature ◽  
Real Space ◽  
Interfacial Structure ◽  
Tem Analysis ◽  
Plan View ◽  
Transmission Electron ◽  
Reconstructed Surface

ABSTRACTReal space plan-view Transmission Electron Microscopy (TEM) of the interfacial structure at the amorphous-Ge / Si (111) interface is presented. Ge is deposited at between room temperature and 150°C on either a 5×5 or 7×7 reconstructed surface. Conventional Plan-view TEM analysis reveals microstructural details such as surface steps, reconstruction phase shift boundaries and the reconstruction itself buried under the amorphous film, features which have previously been seen only as clean surfaces in UHV. Also imaged are small regions where Ge grows epitaxially on the Si surface above room temperature. These are seen to appear preferentially at steps and phase shift boundaries.

Transmission electron microscopy study of Ge implanted into SiC

2002 ◽  
Vol 17 (2) ◽  
pp. 479-486 ◽  
Author(s):  
T. Gorelik ◽  
U. Kaiser ◽  
Ch. Schubert ◽  
W. Wesch ◽  
U. Glatzel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Structural Changes ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Transmission Electron Microscopy Study ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Means Of Transmission

Hexagonal 6H– and 4H–SiC wafers were implanted with (1−1.5) × 1016 cm−2 germanium ions at room temperature and at 700 °C with subsequent annealing between 1000 and 1600 °C. Structural changes in the SiC matrix were studied in detail by means of transmission electron microscopy (TEM). After implantation at room temperature the hexagonal SiC matrix becomes amorphous and, after annealing, recrystallizes into cubic SiC. The latter process was accompanied by the creation of voids and cracks. In case of high-temperature (700 °C) implantation, where amorphization was avoided, no polytype change in as-implanted and annealed SiC wafers was observed. In annealed samples nanocrystalline precipitates with high Ge content were observed in high-resolution TEM images.

scholarly journals Characteristic boundaries associated with three-dimensional twins in hexagonal metals

2020 ◽  
Vol 6 (28) ◽  
pp. eaaz2600 ◽  
Author(s):  
Shujuan Wang ◽  
Mingyu Gong ◽  
Rodney J. McCabe ◽  
Laurent Capolungo ◽  
Jian Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Three Dimensional ◽  
Deformation Mode ◽  
Solute Segregation ◽  
Atomic Scale ◽  
Twin Boundaries ◽  
Hexagonal Close Packed ◽  
Transmission Electron ◽  
Dynamics Simulations

Twinning is a critically important deformation mode in hexagonal close-packed metals. Twins are three-dimensional (3D) domains, whose growth is mediated by the motion of facets bounding the 3D twin domains and influences work hardening in metals. An understanding of twin transformations therefore necessitates that the atomic-scale structure and intrinsic mobilities of facets be known and characterized. The present work addresses the former point by systematically characterizing the boundary structures of 3D {1¯012} twins in magnesium using high-resolution transmission electron microscopy (HRTEM). Eight characteristic facets associated with twin boundaries are reported, five of which have never been experimentally observed before. Further, molecular dynamics simulations suggest that the formation and motion of these facets is associated with the accumulation of twinning dislocations. This work provides insights into understanding the structural character of 3D twins and serves to develop strategies for modulating twin kinetics by modifying twin boundaries, such as solute segregation.

scholarly journals Two-dimensional characterization of three-dimensional nanostructures of magnetic bubbles in Fe3Sn2

2020 ◽  
Author(s):  
Jin Tang ◽  
Yaodong Wu ◽  
Lingyao Kong ◽  
Weiwei Wang ◽  
Yutao Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Microscopy Imaging ◽  
Magnetic Structures ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
High Resolution Tem ◽  
Lorentz Transmission Electron Microscopy

Abstract We report differential phase contrast scanning transmission electron microscopy (TEM) of nanoscale magnetic objects in Kagome ferromagnet Fe3Sn2 nanostructures. This technique can directly detect the deflection angle of a focused electron beam, thus allowing clear identification of the real magnetic structures of two magnetic objects including three-ring and complex arch-shaped vortices in Fe3Sn2 by Lorentz transmission electron microscopy imaging. Numerical calculations based on real material-specific parameters well reproduced the experimental results, showing that the magnetic objects can be attributed to integral magnetizations of two types of complex three-dimensional (3D) magnetic bubbles with depth-modulated spin twisting. Magnetic configurations obtained using the high-resolution TEM are generally considered as two-dimensional (2D) magnetic objects previously. Our results imply the importance of the integral magnetizations of underestimated 3D magnetic structures in 2D TEM magnetic characterizations.

TEM study on the thermostability of hafnium carbide dispersoids in tungsten at ultrahigh temperatures

1993 ◽  
Vol 51 ◽  
pp. 1170-1171
Author(s):  
Mingqi Liu ◽  
John M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Growth Behavior ◽  
Hafnium Carbide ◽  
Metallic Material ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Alloy Strength

Tungsten dispersed by hafnium carbide (HfC) particles has been found to be the strongest metallic material at temperatures above 2000 K. The strength of W-HfC alloy is directly related to the thermostability of HfC particles at ultrahigh temperatures. In the present study, the growth behavior and growth mechanism of HfC particles from 2200 to 3000 K are examined with transmission electron microscopy (TEM) and a correlation between the particle size and alloy strength is established.The examined material was a tungsten-3.6 wt%rhenium-0.35 wt%HfC alloy. The solid solution element rhenium was to improve the fabricability of tungsten at room temperature. Specimens were heated to a temperature between 2200 and 3000 K for two hours and then deformed in tension. After a 5% elongation, the specimens were rapidly cooled down to room temperature at a cooling rate greater than 200 K/s in order to maintain the high temperature substructures which were examined with a JEM-2000FX high resolution TEM.

Microstructures in Pb(In1/2Nb1/2)O3 with the Perovskite B-site Randomness

2012 ◽  
Vol 1397 ◽  
Author(s):  
S. Mori ◽  
K. Kurushima ◽  
K. Kobayashi ◽  
H. Ohwa ◽  
N. Yasuda ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Real Space ◽  
The Other ◽  
Modulated Structure ◽  
Transmission Electron ◽  
Relaxor State ◽  
High Resolution Tem ◽  
Average Size ◽  
Modulation Vector

ABSTRACTWe have investigated microstructures in both the antiferroelectric (AFE) and relaxor states of Pb(In1/2Nb1/2)O3 (PIN) with the perovskite structure by a transmission electron microscopy (TEM). Electron diffraction (ED) experiments revealed that the AFE state is characterized as the modulated structure with the modulation vector of q=1/4 1/4 0. High-resolution TEM images clearly show the coexistence of two types of domains consisting of the modulated and the nonmodulated structures with the 100 ∼ 200 nm size. On the other hand, in the relaxor state there appear two types of diffuse scatterings in the ED patterns. One is diffuse spots at the 1/2 1/2 0-type reciprocal positions and the other is diffuse streaks elongating along the <110> direction around the fundamental spots. The real-space TEM images clearly demonstrate the presence of nanodomains with the average size of ∼ 5 nm. These nanodomains in the relaxor state should be responsible for the characteristic dielectric properties.

Scanning and Transmission Electron Microscopy of Human Red Blood Cells

1969 ◽  
Vol 27 ◽  
pp. 44-45
Author(s):  
A.J. Tousimis ◽  
T.R. Padden
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Blood Cells ◽  
Room Temperature ◽  
Type Specimen ◽  
New Combination ◽  
Human Red Blood Cells ◽  
Transmission Electron ◽  
Microscope Slides ◽  
Scanning Electron

The size, shape and surface morphology of human erythrocytes (RBC) were examined by scanning electron microscopy (SEM), of the fixed material directly and by transmission electron microscopy (TEM) of surface replicas to compare the relative merits of these two observational procedures for this type specimen.A sample of human blood was fixed in glutaraldehyde and washed in distilled water by centrifugation. The washed RBC's were spread on freshly cleaved mica and on aluminum coated microscope slides and then air dried at room temperature. The SEM specimens were rotary coated with 150Å of 60:40- gold:palladium alloy in a vacuum evaporator using a new combination spinning and tilting device. The TEM specimens were preshadowed with platinum and then rotary coated with carbon in the same device. After stripping the RBC-Pt-C composite film, the RBC's were dissolved in 2.5N HNO3 followed by 0.2N NaOH leaving the preshadowed surface replicas showing positive topography.

Formation of Dislocation Channels in Neutron Irradiated Molybdenum

1972 ◽  
Vol 30 ◽  
pp. 672-673
Author(s):  
S. Mahajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Channel Formation ◽  
Early Stages ◽  
Transmission Electron ◽  
Three Stages ◽  
Two Stages ◽  
Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

Simulation of three Dimensional Defect Images in Transmission Electron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 470-471
Author(s):  
W. D. Cooper ◽  
C. S. Hartley ◽  
J. J. Hren
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Three Dimensional ◽  
Crystalline Lattice ◽  
Continuum Models ◽  
Thin Foils ◽  
Transmission Electron ◽  
Microscope Images ◽  
General Computer Program ◽  
General Computer

Interpretation of electron microscope images of crystalline lattice defects can be greatly aided by computer simulation of theoretical contrast from continuum models of such defects in thin foils. Several computer programs exist at the present time, but none are sufficiently general to permit their use as an aid in the identification of the range of defect types encountered in electron microscopy. This paper presents progress in the development of a more general computer program for this purpose which eliminates a number of restrictions contained in other programs. In particular, the program permits a variety of foil geometries and defect types to be simulated.The conventional approximation of non-interacting columns is employed for evaluation of the two-beam dynamical scattering equations by a piecewise solution of the Howie-Whelan equations.

A crystallographic analysis of the CoSi/Si(111) interface using Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 574-575
Author(s):  
A.C. Daykin ◽  
C.J. Kiely ◽  
R.C. Pond ◽  
J.L. Batstone
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Defect Structure ◽  
Room Temperature ◽  
Theoretical Method ◽  
Crystallographic Analysis ◽  
Si Substrate ◽  
Transmission Electron ◽  
Theoretical Predictions

When CoSi2 is grown onto a Si(111) surface it can form in two distinct orientations. A-type CoSi2 has the same orientation as the Si substrate and B-type is rotated by 180° degrees about the [111] surface normal.One method of producing epitaxial CoSi2 is to deposit Co at room temperature and anneal to 650°C.If greater than 10Å of Co is deposited then both A and B-type CoSi2 form via a number of intermediate silicides .The literature suggests that the co-existence of A and B-type CoSi2 is in some way linked to these intermediate silicides analogous to the NiSi2/Si(111) system. The phase which forms prior to complete CoSi2 formation is CoSi. This paper is a crystallographic analysis of the CoSi2/Si(l11) bicrystal using a theoretical method developed by Pond. Transmission electron microscopy (TEM) has been used to verify the theoretical predictions and to characterise the defect structure at the interface.

Sign in / Sign up

Export Citation Format

Share Document