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.

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.

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]).

Twin Boundaries and Stacking Faults in Monazite (Monoclinic LaPO4)

2004 ◽  
Vol 819 ◽  
Author(s):  
Randall S. Hay
Keyword(s):  
Room Temperature ◽  
Deformation Twin ◽  
Stacking Faults ◽  
Temperature Deformation ◽  
Formation Mechanisms ◽  
Twin Boundaries ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Fault Migration ◽  
Lattice Formation

AbstractMonazite (LaPO4) was indented at room temperature. Deformation twin boundaries and stacking faults were characterized by high resolution transmission electron microscopy. Kinked deformation twins were also characterized and analyzed. Three types of stacking faults associated with climb-dissociated partial dislocations were observed. Two were found on twin boundaries, and a third in the lattice. Formation mechanisms are discussed. The superimposition of stacking faults along twin boundaries during deformation twinning and the glide of climb-dissociated partial dislocations allowed by stacking fault migration are discussed. The possible relationship between the formation mechanisms for these defects and the low- temperature recrystallization and self-annealing of defects in monazite is considered.

Overlapping Shockley/Frank Faults in 4H-SiC PiN Diodes

2006 ◽  
Vol 527-529 ◽  
pp. 383-386 ◽  
Author(s):  
Mark E. Twigg ◽  
Robert E. Stahlbush ◽  
Peter A. Losee ◽  
Can Hua Li ◽  
I. Bhat ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Light Emission ◽  
Stacking Faults ◽  
Dark Field ◽  
Pin Diodes ◽  
Plan View ◽  
Planar Defects ◽  
Burgers Vector ◽  
Partial Dislocations ◽  
Transmission Electron

Using light emission imaging (LEI), we have determined that not all planar defects in 4H-SiC PiN diodes expand in response to bias. Accordingly, plan-view transmission electron microscopy (TEM) observations of these diodes indicate that these static planar defects are different in structure from the mobile stacking faults (SFs) that have been previously observed in 4H-SiC PiN diodes. Bright and dark field TEM observations reveal that such planar defects are bounded by partial dislocations, and that the SFs associated with these partials display both Frank and Shockley character. That is, the Burgers vector of such partial dislocations is 1/12<4-403>. For sessile Frank partial dislocations, glide is severely constrained by the need to inject either atoms or vacancies into the expanding faulted layer. Furthermore, these overlapping SFs are seen to be fundamentally different from other planar defects found in 4H-SiC.

Formation of Defects in MBE Re-Grown GaAs Films on GaAs/AlGaAs Heterostructures

2002 ◽  
Vol 744 ◽  
Author(s):  
M. Lamberti ◽  
V. Tokranov ◽  
R. Moore ◽  
M. Yakimov ◽  
A. Katsnelson ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Defect Formation ◽  
Defect Density ◽  
Ion Beam ◽  
Stacking Faults ◽  
Tem Analysis ◽  
Planar Defects ◽  
Site Specific ◽  
Al Content ◽  
Gaas Films

ABSTRACTIn the present work, we examine the formation of defects on the sidewall slope in 1 μm - thick GaAs layers regrown on GaAs/AlGaAs heterostructures. Site-specific TEM specimens of sidewall slopes are obtained using focused ion beam combined with lift-out method. TEM analysis shows planar defects, such as stacking faults and microtwins, dislocations and large twinned areas, nucleating on the AlGaAs surfaces. SIMS and EDX reveal an increase in carbon and oxygen at the interface. The defect density increased with Al content exceeding 1010 cm-2 on Al0.4Ga0.6As. The defect formation is related to the oxidation of Al-containing surfaces.

Observations of Defect Generation at Stacking Faults in Boron Diffused and Oxidized Silicon Films

1973 ◽  
Vol 31 ◽  
pp. 128-129 ◽  
Author(s):  
A. G. Cullis ◽  
D. M. Maher ◽  
C. M. Hsieh
Keyword(s):  
Electron Microscope ◽  
Oxide Layer ◽  
Silicon Wafer ◽  
Transmission Electron Microscope ◽  
Defect Formation ◽  
Stacking Faults ◽  
Epitaxial Silicon ◽  
Partial Dislocations ◽  
Substrate Side ◽  
Transmission Electron

Recently, the transmission electron microscope (TEM) has been used to study the formation and geometry of defect colonies in annealed and quenched silicon and in thermally oxidized and boron diffused silicon. The purpose of the present study was to examine subsidiary defect formation which can occur during the climb of Frank partial dislocations bounding stacking faults in boron diffused and subsequently thermally oxidized silicon. In these experiments, a {001} epitaxial silicon wafer (n-type, 1Ω−cm) was boron diffused (to 5×1018/cm3), and then steam oxidized for 2 hr at 1050°C. Prior to oxidation the wafer was cleaned using HF as a last step. After oxidation the oxide layer was first removed and then specimens from the wafer were chemically thinned from the substrate side for TEM observations (200 kV).

Planar Defects in Small Particles

1985 ◽  
Vol 43 ◽  
pp. 392-393
Author(s):  
R. Pérez ◽  
M. Avalos-Borja
Keyword(s):  
Stacking Faults ◽  
Particle Growth ◽  
Small Particles ◽  
Planar Defects ◽  
Metallic Particles ◽  
Weak Beam ◽  
Transmission Electron ◽  
Imaging Conditions

Transmission electron microscope techniques have been extensively used in the determination of the morphology of fine metallic particles. These techniques have been of particular importance in obtaining topographical information during particle growth and sintering. Thus, for example, it has been found that some of the most elementary forms consist of half cubo-octahedral units with (111) faces and (100) basis. Furthermore, full cubo-octahedral units have also been found, some of them showing stacking faults (SF) through the particles.It is important to point out that the characterization of this type of planar defects in small metallic particles has commonly been based on geometrical con. siderations. Additionally, the imaging conditions which have been used are the so-called weak beam (WB) diffraction conditions. Recent investigations have shown, on the other hand, that SF images under WB conditions present serious inconveniences, for example, contrast asymmetries in SF images which are not totally explained. Another difficulty with these WB fault images arises from twin boundaries which display image contrast similar to SF when a common reflection is strongly excited.

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.

Microstructural investigation of BaTiO3 thin films deposited on (001) MgO

2002 ◽  
Vol 17 (8) ◽  
pp. 1923-1931 ◽  
Author(s):  
C. H. Lei ◽  
G. Van Tendeloo ◽  
M. Siegert ◽  
J. Schubert
Keyword(s):  
Thin Films ◽  
Displacement Vector ◽  
Stacking Faults ◽  
Pulsed Laser ◽  
Interfacial Structure ◽  
Antiphase Boundaries ◽  
Microstructural Investigation ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
High Resolution Microscopy

The microstructure of BaTiO3 thin films, epitaxially deposited on (001) MgO by pulsed laser ablation, has been investigated by transmission electron microscopy. The films are always c-axis-orientated, but dislocations, {111} stacking faults, and antiphase boundaries are frequently observed. Conventional TEM and high-resolution microscopy allow one to deduce the Burgers vectors of dislocations as b1 = 〈100〉 or b2 = 〈110〉, both being perfect dislocations. Most extrinsic stacking faults are ending at 1/3〈112〉 or 1/3〈111〉 partial dislocations; the displacement vector of the antiphase boundaries is 1/2〈101〉. Studying the interfacial structure by means of zone images taken along [100] and [110] shows that the misfit is mainly released by dislocations with Burgers vectors of 1/2〈110〉 and 1/2〈101〉.

Influence of planar defects on powder diffractograms of fcc metals

2002 ◽  
Vol 17 (4) ◽  
pp. 270-277 ◽  
Author(s):  
A. I. Ustinov ◽  
N. M. Budarina
Keyword(s):  
Powder Diffraction ◽  
Stacking Faults ◽  
Diffraction Peak ◽  
High Concentration ◽  
Planar Defects ◽  
X Ray ◽  
Fcc Metals ◽  
Different Types ◽  
High Degree ◽  
Kinematic Approach

X-ray powder diffractograms from fcc crystals containing high concentration (more than 1%) of planar defects [deformation stacking faults (SF), double deformation SF, twin boundaries (TB)] have been simulated by Monte Carlo method in kinematic approach. It was shown that the characteristics of powder diffraction peak profiles (except peaks with indexes H00) dependent nonmonotonically on PD concentration, during which peak maximums stay in Bragg positions. An addition point to emphasize is that an appearance of TB only in the crystal not affects on position of all peaks. Several types of PD to be occurred simultaneously in the crystal influence on powder diffractograms additively. Peculiarities of the powder diffraction pattern inherent in different types of PD have been revealed to permit predominant PD type to be found with a high degree of accuracy based on experimental data.

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