Characterization of Defect Structures in 3C-SiC Single Crystals Using Synchrotron White Beam X-ray Topography

1996 ◽  
Vol 423 ◽  
Author(s):  
W. Huang ◽  
M. Dudley ◽  
C. Fazi
Keyword(s):  
Single Crystals ◽  
Stacking Faults ◽  
Interference Microscopy ◽  
Defect Structures ◽  
Growth Sector ◽  
X Ray ◽  
Partial Dislocations ◽  
White Beam ◽  
Transmission And Reflection

AbstractDefect structures in (111) 3C-SiC single crystals, grown using the Baikov technique, have been studied using Synchrotron White Beam X-ray Topography (SWBXT). The major types of defects include complex growth sector boundary structures, double positioning twins, stacking faults on { 111 } planes, inclusions and dislocations (including growth dislocations and partial dislocations bounding stacking faults). Detailed stacking fault and double positioning twin configurations are determined using a combination of Nomarski interference microscopy, SEM and white beam x-ray topography in both transmission and reflection geometries. Possible defect generation phenomena are discussed.

Characterization of Defect Structures in Lely 6H-SiC Single Crystals Using Synchrotron White Beam X-Ray Topography

1994 ◽  
Vol 375 ◽  
Author(s):  
W. Huang ◽  
S. Wang ◽  
M. Dudley ◽  
P. Neudeck ◽  
J. A. Powell ◽  
...  
Keyword(s):  
Single Crystals ◽  
Basal Plane ◽  
Stacking Faults ◽  
Defect Structures ◽  
Dislocation Generation ◽  
X Ray ◽  
Partial Dislocations ◽  
White Beam ◽  
Generation Mechanisms

AbstractDefect structures in Lely SiC single crystals have been studied using synchrotron white beam X-ray topography. Basal plane dislocations and stacking faults probably generated during post-growth cooling are clearly revealed. For both perfect dislocations and partial dislocations bounding the stacking faults, Burgers vectors and line directions are determined from contrast extinction analysis as well as projected direction analysis on different topographic images. The fault planes and fault vectors of the stacking faults were determined using contrast extinction analysis. Possible dislocation generation mechanisms are briefly discussed.

Characterization of Defect Structures in SiC Single Crystals Using Synchrotron X-Ray Topography

1993 ◽  
Vol 307 ◽  
Author(s):  
S. Wang ◽  
M. Dudley ◽  
C. Carter ◽  
D. Asbury ◽  
C. Fazit
Keyword(s):  
Detailed Analysis ◽  
Single Crystals ◽  
Basal Plane ◽  
Defect Structures ◽  
Dislocation Generation ◽  
Screw Dislocations ◽  
X Ray ◽  
White Beam

ABSTRACTSynchrotron white beam X-ray topography has been used to characterize defect structures in 6H-SiC wafers grown on (0001) seeds. Two major types of defects are observed: super screw dislocations approximately perpendicular to the basal plane and dislocation networks lying in the basal plane. The super screw dislocations, which have open cores, are growth dislocations. These dislocations act as sources and/or sinks for the glide dislocation networks. Detailed analysis and discussion of dislocation generation phenomena and Burgers vectors will be presented.

Characterization of structural defects in MLEK grown InP single crystals using synchrotron white beam X-ray topography

1997 ◽  
Vol 174 (1-4) ◽  
pp. 230-237 ◽  
Author(s):  
H. Chung ◽  
W. Si ◽  
M. Dudley ◽  
A. Anselmo ◽  
D.F. Bliss ◽  
...  
Keyword(s):  
Single Crystals ◽  
Structural Defects ◽  
X Ray ◽  
White Beam

Synchrotron X-Ray Topographic Study of Defects in High Quality, Flux Grown Ktiopo4 Single Crystals

1993 ◽  
Vol 307 ◽  
Author(s):  
S. Wang ◽  
M. Dudley ◽  
L. K. Cheng ◽  
J. D. Bierlein
Keyword(s):  
Detailed Analysis ◽  
Single Crystals ◽  
Domain Walls ◽  
Defect Structures ◽  
Growth Sector ◽  
High Quality ◽  
X Ray ◽  
Free Region ◽  
Ferroelectric Domains ◽  
Section Topography

ABSTRACTDefect structures in large, high quality flux-grown KTP single crystals have been studied by using synchrotron white beam X-ray topography. Growth dislocations, inclusions, growth sector boundaries, growth bands and surface micro-scratches were imaged. A number of planar defects in the dislocation-free region are imaged and determined to be inversion twin lamellae (lamellar ferroelectric domains) which have never been previously reported in KTP crystals. These inversion twin lamellae were also studied by section topography. Detailed analysis of observed contrast revealed that the domain walls bounding the lamellae are faulted with a fault vector of ½[0±1±1]. This fault vector seems to be consistent with the atomic structure of KTP. A detailed analysis is presented and discussed.

Characterization of Superconducting PrBa2Cu3Ox

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3242-3250
Author(s):  
Zhigang Zou ◽  
Jinhua Ye ◽  
Kunihiko Oka ◽  
Yoshikazu Nishihara
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystals ◽  
Superconducting State ◽  
Magnetic Measurement ◽  
Stacking Faults ◽  
Critical Magnetic Field ◽  
Oxygen Annealing ◽  
X Ray

The crystal structures of superconducting and nonsuperconducting PrBa2Cu3O x crystals were investigated using a single crystal X-ray precession camera. A large amount of stacking faults were observed in h0l reflections of as-grown supconducting PrBa2Cu3O x single crystals. These diffusing could be relaxed after oxygen annealing. Meanwhile, intensities of 003n (n = 1, 2, 3…) diffraction reflections of annealed crystal were increased significantly, indicating that the structural ordering of 1/3n unit cell was improved. Magnetic measurement exhibited that the superconducting state of PrBa2Cu3O x , is sensitive to magnetic fields and the magnetic fields dependence of the flux melting temperature showed that the sample has the smaller critical magnetic field than YBa2Cu3O x.

Defect structures of Nb1+αS2 sulfidation scales

1992 ◽  
Vol 50 (1) ◽  
pp. 38-39
Author(s):  
Chuxin Zhou ◽  
L. W. Hobbs
Keyword(s):  
Stacking Faults ◽  
Rhombohedral Structure ◽  
Stacking Sequence ◽  
Defect Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plane Normal ◽  
Lower Case ◽  
Sulfur Layer ◽  
Two Phases

One of the major purposes in the present work is to study the high temperature sulfidation properties of Nb in severe sulfidizing environments. Kinetically, the sulfidation rate of Nb is satisfactorily slow, but the microstructures and non-stoichiometry of Nb1+αS2 challenge conventional oxidation/sulfidation theory and defect models of non-stoichiometric compounds. This challenge reflects our limited knowledge of the dependence of kinetics and atomic migration processes in solid state materials on their defect structures.Figure 1 shows a high resolution image of a platelet from the middle portion of the Nb1+αS2 scale. A thin lamellar heterogeneity (about 5nm) is observed. From X-ray diffraction results, we have shown that Nb1+αS2 scale is principally rhombohedral structure, but 2H-NbS2 can result locally due to stacking faults, because the only difference between these 2H and 3R phases is variation in the stacking sequence along the c axis. Following an ABC notation, we use capital letters A, B and C to represent the sulfur layer, and lower case letters a, b and c to refer to Nb layers. For example, the stacking sequence of 2H phase is AbACbCA, which is a ∼12Å period along the c axis; the stacking sequence of 3R phase is AbABcBCaCA to form an ∼18Å period along the c axis. Intergrowth of these two phases can take place at stacking faults or by a shear in the basal plane normal to the c axis.

Characterization of Natural and Synthesized FeTiO3 Crystals With RBS/PIXE/XRD

1997 ◽  
Vol 07 (03n04) ◽  
pp. 265-275
Author(s):  
R. Q. Zhang ◽  
S. Yamamoto ◽  
Z. N. Dai ◽  
K. Narumi ◽  
A. Miyashita ◽  
...  
Keyword(s):  
Single Crystals ◽  
Ion Beam ◽  
Pressure Control ◽  
Floating Zone ◽  
X Ray Diffraction ◽  
X Ray ◽  
Beam Analysis ◽  
Ppm Level

Natural FeTiO 3 (illuminate) and synthesized FeTiO 3, single crystals were characterized by Rutherford backscattering spectroscopy combined with channeling technique and particle-induced x-ray emission (RBS-C and PIXE). The results obtained by the ion beam analysis were supplemented by the x-ray diffraction analysis to identify the crystallographic phase. Oriented single crystals of synthesized FeTiO 3 were grown under the pressure control of CO 2 and H 2 mixture gas using a single-crystal floating zone technique. The crystal quality of synthesized FeTiO 3 single crystals could be improved by the thermal treatment but the exact pressure control is needed to avoid the precipitation of Fe 2 O 3 even during the annealing procedure. Natural FeTiO 3 contains several kinds of impurities such as Mn , Mg , Na and Si . The synthesized samples contain Al , Si and Na which are around 100 ppm level as impurities. The PBS-C results of the natural sample imply that Mn impurities occupy the Fe sublattice in FeTiO 3 or in mixed phase between ilmenite and hematite.

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