Atomic Structures and Defects of As-Grown Nb1+αS2 Platelets on Nb Substrates

1992 ◽  
Vol 295 ◽  
Author(s):  
Chuxin Zhou ◽  
L. W. Hobbs
Keyword(s):  
Crystal Structure ◽  
Grain Boundaries ◽  
Diffraction Pattern ◽  
Atomic Structure ◽  
Stacking Faults ◽  
Planar Defect ◽  
Defect Structures ◽  
Planar Defects ◽  
Atomic Structures ◽  
Octahedral Sites

AbstractThe interlocking of Nb1+αS2 platelets developed during sulfidation of Nb results in formation of a compact scale. The atomic structure and defects of these platelets were investigated using HREM. The resulting microstructure is very different from conventional microstructure consisting of polygonal grains and polyhedral grain boundaries because of the anisotropy of the crystal structure. The principal phase was identified as 3R-Nb2+αS2 intergrown with 2H-Nb1+αS2, or with some other arrangement of S-Nb-S slabs. The -S6- octahedral sites between two S-Nb-S slabs provide accommodation for extra Nb or foreign atoms and the large non-stoichiometry of Nb1+αS2. Stacking faults along the c axis account for the high density of planar defect structures observed within almost every platelet. Axial lattice fringe images and streaking in the diffraction pattern indicate that the planar defects are normal to the c direction.

Flux-pinning-related defect structures in melt-processed YBa2Cu3O7-x

1993 ◽  
Vol 51 ◽  
pp. 936-937
Author(s):  
Z. L. Wang ◽  
R. Kontra ◽  
A. Goyal ◽  
D. M. Kroeger ◽  
L.F. Allard
Keyword(s):  
Volume Fraction ◽  
Local Density ◽  
Stacking Faults ◽  
Image Resolution ◽  
Defect Structures ◽  
Atomic Structures ◽  
Transmission Electron ◽  
Point Image ◽  
Related Defect ◽  
Point To Point

Previous studies of Y2BaCuO5/YBa2Cu3O7-δ(Y211/Y123) interfaces in melt-processed and quench-melt-growth processed YBa2Cu3O7-δ using high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) have revealed a high local density of stacking faults in Y123, near the Y211/Y123 interfaces. Calculations made using simple energy considerations suggested that these stacking faults may act as effective flux-pinners and may explain the observations of increased Jc with increasing volume fraction of Y211. The present paper is intended to determine the atomic structures of the observed defects. HRTEM imaging was performed using a Philips CM30 (300 kV) TEM with a point-to-point image resolution of 2.3 Å. Nano-probe EDS analysis was performed using a Philips EM400 TEM/STEM (100 kV) equipped with a field emission gun (FEG), which generated an electron probe of less than 20 Å in diameter.Stacking faults produced by excess single Cu-O layers: Figure 1 shows a HRTEM image of a Y123 film viewed along [100] (or [010]).

Crystalline perfection of chemical vapor deposited diamond films

1990 ◽  
Vol 5 (8) ◽  
pp. 1591-1594 ◽  
Author(s):  
A. V. Hetherington ◽  
C. J. H. Wort ◽  
P. Southworth
Keyword(s):  
Grain Boundaries ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Stacking Faults ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Growth Conditions ◽  
Crystalline Perfection ◽  
Planar Defects ◽  
Chemical Vapor Deposited

The crystalline perfection of microwave plasma assisted chemical vapor deposited (MPACVD) diamond films grown under various conditions has been examined by TEM. Most CVD diamond films thus far reported contain a high density of defects, predominantly twins and stacking faults on {111} planes. We show that under appropriate growth conditions, these planar defects are eliminated from the center of the crystallites, and occur only at grain boundaries where the growing crystallites meet.

Defects in Germanium Nanocrystals Produced by Ion Implantation

2013 ◽  
Vol 709 ◽  
pp. 148-152
Author(s):  
Yu Juan Zhang ◽  
Lei Shang
Keyword(s):  
Electron Microscopy ◽  
Light Emission ◽  
Stacking Faults ◽  
Implantation Dose ◽  
Defect Structures ◽  
High Temperature Annealing ◽  
Planar Defects ◽  
Transmission Electron ◽  
Microstructural Defects ◽  
Germanium Nanocrystals

Germanium nanocrystals (Ge-nc) were produced by the implantation of Ge+ into a SiO2 film deposited on (100) Si, followed by a high-temperature annealing. High-resolution transmission electron microscopy (HRTEM) has been used to investigate the defect structures inside the Ge-nc produced by different implantation doses (1×1016, 2×1016, 4×1016 and 8×1016 cm-2). It has been found that the planar defects such as nanotwins and stacking faults (SFs) are dominant in Ge-nc (60%) for the samples with implantation doses higher than 2×1016 cm-2, while for the sample with an implantation dose lower than 1×1016 cm-2, fewer planar defects are observed in the Ge-nc (20%). The percentages of nanotwins in the planar defects are 87%, 77%, 67% and 60% in four samples, respectively. The twinning structures include single twins, double twins and multiple twins. We also found that there are only SFs in some nanocrystals, and in others the SFs coexist with twins. These microstructural defects are expected to play an important role in the light emission from the Ge-nc.

First-Principles Calculations of Stacking Faults and Grain Boundaries in Metals

1990 ◽  
Vol 213 ◽  
Author(s):  
K. Hampel ◽  
D.D. Vvedensky ◽  
S. Crampin
Keyword(s):  
Magnetic Properties ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
First Principles ◽  
Stacking Faults ◽  
First Principles Calculations ◽  
Comprehensive Description ◽  
Planar Defects ◽  
Detailed Understanding ◽  
Defect Energies

ABSTRACTA detailed understanding of planar defects plays an important role in the search for a comprehensive description of the mechanical behaviour of metals and alloys. We present calculations for isolated stacking faults and grain boundaries using the layer Korringa-Kohn-Rostoker method including an assessment of the force theorem, which has already proven itself in evaluating defect energies for elemental close-packed metals. These ab initio total energy calculations will be supplemented by a study of the changes in bonding and local magnetic properties near a symmetric Σ5 (310) grain boundary in Fe

Energies and Atomic Structures of Grain Boundaries in Diamond: Comparison With Grain Boundaries in Silicon

1994 ◽  
Vol 339 ◽  
Author(s):  
M. Kohyama ◽  
H. Ichinose ◽  
Y. Ishida ◽  
M. Nakanose
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Interfacial Energy ◽  
Atomic Structure ◽  
Tight Binding ◽  
Tilt Boundary ◽  
Atomic Structures ◽  
Fundamental Properties ◽  
Diamond Thin Films ◽  
First Time

ABSTRACTFairly different features of grain boundaries in diamond from those in Si were experimentally observed in diamond thin films. As the first step in order to understand the fundamental properties of grain boundaries in diamond, the energy and atomic structure of the {122} σ=9 tilt boundary have been calculated for the first time by using the tight-binding electronic theory. The results have been compared with the calculations of the same boundary and the {111} σ=3 boundary in Si. It has been shown that the σ=9 boundary in diamond has a very large interfacial energy caused by the large bond rigidity as compared with the boundaries in Si and the {111}σ=3 boundary in diamond. This point should be related to the observation that the {122}σ =9 boundary is rarely found in diamond thin films.

Twin boundaries in hausmannite (α-Mn3O4)

1987 ◽  
Vol 45 ◽  
pp. 158-159
Author(s):  
L. A. Tietz ◽  
R. Dieckmann ◽  
C. B. Carter
Keyword(s):  
Crystal Structure ◽  
Point Defects ◽  
Spinel Structure ◽  
Manganese Oxides ◽  
Defect Structures ◽  
Spinel Type ◽  
Octahedral Sites ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Type Crystal

The manganese oxides hausmannite (Mn3-δ O4) and manganosite (Mn1-△O) have recently been characterized by Keller and Dieckmann in terms of their point defect structures and transport properties and a phase diagram has been compiled for the Mn1-△O-Mn3-δO4 portion of the Mn-O system. As might be expected, the manganese oxides bear a strong resemblence to the iron oxides. Both Fe1-△O and Mn1-△O (a=4.44Å) have the NaCl-type structure and are highly non-stoichiometnc, the major point defects being cation vacancies. In Mn1-△O, △ is of the order of 0.1 at 1400 °C and high oxygen activities. Likewise, Mn3-δO4, is the crystallographic analog of Fe3-δO4 (magnetite) but with one major difference; although both compounds have the spinel-type crystal structure, Mn3-δO4 is cubic only above 1150 °C with aα=8.42Å. Below this temperature, it transforms to a tetragonally distorted spinel structure with aα=8.14 Å, cα=9.47 Å, and c/a=1.16. This distortion has been attributed to the Jahn-Teller effect of Mn+3 cations in the octahedral sites of the spinel structure. The purpose of this study is to describe the crystallography of transformations around the Mn1-△O-Mn3-δO4 equilibrium.

Formation of Defect Structures during Annealing of Cold-deformed L10-ordered equiatomic FePd Intermetallics

2004 ◽  
Vol 842 ◽  
Author(s):  
Anirudha R. Deshpande ◽  
Jörg M.K. Wiezorek
Keyword(s):  
Defect Formation ◽  
Driving Forces ◽  
Cold Deformation ◽  
Stacking Faults ◽  
Formation Mechanisms ◽  
Defect Structures ◽  
Antiphase Boundaries ◽  
Planar Defects ◽  
Fcc Metals ◽  
Transmission Electron

ABSTRACTPlanar defects produced in L10-ordered FePd during annealing after cold-deformation in the disordered cubic state have been characterized by transmission electron microscopy (TEM). The defects evolving during annealing include arrays of overlapping stacking faults (SF's), {111}-conjugated microtwins (μT's) and thermal antiphase boundaries (APB's). The defect formation mechanisms proposed here are similar to twinning mechanism reported for FCC-metals during annealing. Thus, SF arrays and faulted μT's in the L10-ordered FePd appear to form during the early stages of annealing by atomic attachment faulting on {111}-facets of the transformation interfaces. During later stages of annealing the reduced amount and the change in nature of the driving forces for the microstructural rearrangement result in changes in the predominant defect formation mechanism. The features of the defect genesis in L10-FePd are discussed with respect to solid-state transformations during processing of these ferromagnetic intermetallics.

In-plane crystalline anisotropy of bulk β-Ga2O3

2021 ◽  
Vol 54 (4) ◽  
Author(s):  
Xiaocui Ma ◽  
Rui Xu ◽  
Jianfang Xu ◽  
Leiying Ying ◽  
Yang Mei ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Grain Boundaries ◽  
Bulk Material ◽  
Stacking Faults ◽  
Coherent Scattering ◽  
Limiting Factors ◽  
X Ray Diffraction ◽  
Limited Size ◽  
X Ray ◽  
Crystalline Anisotropy

The anisotropy of X-ray diffraction scanning of (201) β-Ga2O3 bulk material has been investigated. Symmetric rocking curves (RCs) exhibit distinctly different broadening along different azimuths, with a maximum along [102] and a minimum along a direction rotated by 30° from [010]. Williamson–Hall analysis was applied to study possible factors causing the broadening in these RCs, including instrumental factors, mosaic tilt and coherent scattering. It was found that the RC broadening is determined by both isotropic mosaic tilt and anisotropy in the length over which the crystal structure is not disrupted by limiting factors such as grain boundaries or stacking faults, which we term the `lateral limited size'. In this case, the lateral limited size is governed by {200} stacking faults along the [102] direction and grain boundaries along the [010] direction. The result presents a new anisotropy characteristic of (201) β-Ga2O3.

Atomic Structure Of Grain Boundaries And Interfaces In Iiinitrides Epitaxial Systems

1997 ◽  
Vol 482 ◽  
Author(s):  
S. Ruvimov ◽  
Z. Liliental-Weber ◽  
J. Washburn ◽  
H. Amano ◽  
I. Akasaki ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Atomic Structure ◽  
Stacking Faults ◽  
High Resolution Electron Microscopy ◽  
Epitaxial Layers ◽  
Resolution Electron

AbstractHigh resolution electron microscopy (HREM) was applied to study atomic structure of stacking faults, grain boundaries and interfaces in III-nitrides epitaxial layers grown by MOVPE on sapphire. Defects formed in GaN epitaxial layers grown by MOVPE were reviewed in comparison with those in MBE grown materials

Atomic Structures of Planar Defects in Si and GaAs

1992 ◽  
Vol 262 ◽  
Author(s):  
S. Takeda ◽  
S. Muto ◽  
M. Hirata
Keyword(s):  
Experimental Evidence ◽  
Diffuse Scattering ◽  
Planar Defect ◽  
Dangling Bond ◽  
Hrem Image ◽  
Planar Defects ◽  
Atomic Structures ◽  
Gaas Matrix ◽  
Si Doped ◽  
Diffraction Patterns

ABSTRACTAtomic structures of planar defects in Si and GaAs have been studied by TEM. An HREM image of the edge of {113} planar defect has been obtained with <110> incidence. An analysis of the image has showed diat the edge consists of 5-, 6- and 7-membered rings without dangling bond. Anisotropie morphology of the defect could be understood from the model proposed in this report. Weak diffuse scattering and an extinction rule in diffraction patterns from the defect have been found. The experimental evidence has supported the model of the {113} defect.A planar defect on {111} in a heavily Si doped GaAs has been studied. The result has indicated that Si precipitates on the two {111} net planes inserted in the GaAs matrix.

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