High-Resolution Observation of Twinning in Fe1-XS Crystals

1985 ◽  
Vol 43 ◽  
pp. 224-225 ◽  
Author(s):  
Thao A. Nguyen ◽  
Linn W. Hobbs ◽  
Peter R. Buseck
Keyword(s):  
High Resolution ◽  
Iron Sulfide ◽  
Optical Parameters ◽  
Planar Defects ◽  
Electrical And Magnetic Properties ◽  
Transmission Electron ◽  
Resolution Observation ◽  
Half Angle ◽  
Lattice Images

The ordering of iron vacancies in highly nonstoichiometric iron sulfide compounds (Fe1-xS, 0 ⩽ x ⩽ 0.125) at temperature below 425K give rise to at least two different superstructures and a number of possible planar defect configurations. These ordered iron vacancies and associated planar defects are believed to influence greatly the electrical and magnetic properties of Fe1-xS crystals. Extensive efforts, employing high resolution transmission electron microscopy, to characterize the ordering of iron vacancies and associated planar defects have been carried out by Nguyen and Hobbs, Pierce and Buseck, and Nakazawa, et al. In this paper we report the characterization of twin boundaries in iron sulfide crystal of composition nominally Fe9S10.Many beam lattice images of crushed synthetic Fe9S10 crystals were obtained in a top-entry JEM 200CX transmission electron microscope. Relevant electron optical parameters were Cs = 1.2mm; divergence half-angle α = 0.5mrad; and an objective aperture which allowed electron beams up to 5nm-1 to contribute to the final image.

Theoretical Modeling and Experimental Characterization of Planar Defects in Y2Ba4Cu6+Xo14+X

1990 ◽  
Vol 209 ◽  
Author(s):  
C.P. Burmester ◽  
M. Fendorf ◽  
L.T. Wille ◽  
R. Gronsky
Keyword(s):  
Monte Carlo ◽  
High Resolution ◽  
Three Dimensional ◽  
Transformation Mechanism ◽  
Planar Defects ◽  
Transmission Electron ◽  
High Resolution Images ◽  
Equilibrium Structures ◽  
Crystallographic Defects

Crystallographic defects and phase transformations in the system Y2Ba4Cu6+xO14+x(0≤≤4) are investigated by high resolution transmission electron microscopy (TEM) and static lattice, three dimensional Monte Carlo computer simulations. High resolution images of partially transformed (x=2 to x=l) material reveal a prevalence of CuO planar defects (stackingfaults) associated with the transformation and an absence of disturbance to the perovskite Ba-Y-Ba blocks. An atomic mechanism involving the intercalation and removal of extra CuO planes by partial dislocation climb, and requiring only a-b plane diffusion, is developed for the formation of such planar defects during changes in the layered YBaCuO crystal structure. Monte Carlo simulations based on the proposed transformation mechanism accurately reproduce the observed defects andknown equilibrium structures.

Characterization of the Structure and Polarity of Twin Boundaries in GaP

1998 ◽  
Vol 510 ◽  
Author(s):  
Dov Cohent ◽  
D.L. Medlin ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Twin Boundary ◽  
Atomic Structure ◽  
Twin Boundaries ◽  
Planar Defects ◽  
Transmission Electron ◽  
Crystallographic Planes

AbstractThe structure of planar defects in GaP films grown by MBE on Si (110) was investigated by transmission electron microscopy. Growth of GaP films on the (110) surface produced numerous microtwins which formed both first and second order twin boundaries. Using high-resolution transmission electron microscopy, the atomic structure of Σ=3 and Σ=9 twin boundaries were studied. Both the Σ=3 and Σ=9 interfaces were observed to facet along specific crystallographic planes. Geometric models of the Σ=9 {221} twin boundary accounting for different polar bonding configurations were proposed and compared with experimental observations.

Point and planar defects in the iron sulfide compounds Fe1-xS

1984 ◽  
Vol 42 ◽  
pp. 434-435
Author(s):  
Thao A. Nguyen
Keyword(s):  
Low Temperatures ◽  
Direct Evidence ◽  
Iron Sulfide ◽  
Planar Defects ◽  
Selective Area ◽  
Vacancy Ordering ◽  
Different Types ◽  
Lattice Images ◽  
The Subject ◽  
Beam Lattice

It is well known that the large deviations from stoichiometry in iron sulfide compounds, Fe1-xS (0≤x≤0.125), are accommodated by iron vacancies which order and form superstructures at low temperatures. Although the ordering of the iron vacancies has been well established, the modes of vacancy ordering, hence superstructures, as a function of composition and temperature are still the subject of much controversy. This investigation gives direct evidence from many-beam lattice images of Fe1-xS that the 4C superstructure transforms into the 3C superstructure (Fig. 1) rather than the MC phase as previously suggested. Also observed are an intrinsic stacking fault in the sulfur sublattice and two different types of vacancy-ordering antiphase boundaries. Evidence from selective area optical diffractograms suggests that these planar defects complicate the diffraction pattern greatly.

High-resolution transmission electron microscopic study of highly oxygen doped silicon layer

1989 ◽  
Vol 47 ◽  
pp. 692-693
Author(s):  
H. Takaoka ◽  
M. Tomita ◽  
T. Hayashi
Keyword(s):  
High Resolution ◽  
Oxygen Concentration ◽  
Silicon Layer ◽  
Detailed Structure ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Doped Silicon ◽  
Argon Ion

High resolution transmission electron microscopy (HRTEM) is the effective technique for characterization of detailed structure of semiconductor materials. Oxygen is one of the important impurities in semiconductors. Detailed structure of highly oxygen doped silicon has not clearly investigated yet. This report describes detailed structure of highly oxygen doped silicon observed by HRTEM. Both samples prepared by Molecular beam epitaxy (MBE) and ion implantation were observed to investigate effects of oxygen concentration and doping methods to the crystal structure.The observed oxygen doped samples were prepared by MBE method in oxygen environment on (111) substrates. Oxygen concentration was about 1021 atoms/cm3. Another sample was silicon of (100) orientation implanted with oxygen ions at an energy of 180 keV. Oxygen concentration of this sample was about 1020 atoms/cm3 Cross-sectional specimens of (011) orientation were prepared by argon ion thinning and were observed by TEM at an accelerating voltage of 400 kV.

scholarly journals Synthesize and Characterization of Hollow Boron-Nitride Nanocages

2009 ◽  
Vol 2009 ◽  
pp. 1-4 ◽  
Author(s):  
W. S. Zhang ◽  
J. G. Zheng ◽  
W. F. Li ◽  
D. Y. Geng ◽  
Z. D. Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Boron Nitride ◽  
Growth Mechanism ◽  
Spherical Shape ◽  
Amorphous Boron ◽  
Transmission Electron ◽  
Ammonia Atmosphere

The boron-nitride (BN) nanocages are synthesized by nitrogenation of amorphous boron nanoparticles at 1073 K under nitrogen and ammonia atmosphere. The BN nanocages exhibit a well-crystallized feature with nearly pentagonal or spherical shape, depending on their size. High-resolution transmission electron microscopy studies reveal that they are hollow nanocages. The growth mechanism of the BN nanocages is proposed.

Structural characterization of the n = 5 layered perovskite neodymium titanate using high-resolution transmission electron microscopy and image reconstruction

2003 ◽  
Vol 59 (4) ◽  
pp. 449-455 ◽  
Author(s):  
Maria Sayagués ◽  
Katherine Titmuss ◽  
Rudiger Meyer ◽  
Angus Kirkland ◽  
Jeremy Sloan ◽  
...  
Keyword(s):  
High Resolution ◽  
Plane Wave ◽  
Layered Perovskite ◽  
Exit Plane ◽  
Anion Sublattice ◽  
Oxygen Anion ◽  
Enhanced Resolution ◽  
Transmission Electron ◽  
Cation Sites

The structure of Nd5Ti5O17 has been refined from a reconstruction of the specimen exit-plane wave restored from a series of incrementally defocused high-resolution transmission electron microscope (HRTEM) images. The phase of the exit-plane wave shows contrast attributable to the oxygen anion sublattice and coupled with simulations provides confirmation of the composition of the cation sites as a function of sample thickness. The enhanced resolution in the exit-plane wave additionally allows a direct measurement of the `skewing' of the perovskite slabs.

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