High-resolution electron microscopy of metal/metal and metal/metal-oxide interfaces in the Ag/Ni and Au/Ni systems

1990 ◽  
Vol 5 (9) ◽  
pp. 1995-2003 ◽  
Author(s):  
Y. Gao ◽  
Karl L. Merkle
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Metal Oxide ◽  
High Resolution Electron Microscopy ◽  
Misfit Dislocations ◽  
Oxide Systems ◽  
Lattice Statics ◽  
Embedded Atom ◽  
Resolution Electron ◽  
Metal Metal

The atomic structures of heterophase interfaces with large misfits (>14% in Ag/Ni and Au/Ni) and with small misfits (∼2% in Ag/NiO and Au/NiO) have been studied by high-resolution electron microscopy (HREM). It is found that all interfaces are strongly faceted on (111) planes. This indicates that (111) interfaces have the lowest interfacial energy in both metal/metal and metal/metal-oxide systems. For the metal interfaces, this also agrees with determinations of interfacial energies by lattice statics calculations. The large misfit of Ag/Ni and Au/Ni interfaces is accommodated by misfit dislocations. Observations of misfit localization by HREM are in good agreement with images derived from computer simulation, based on relaxed structures, obtained in embedded atom calculations. All misfit dislocations at the Ag/Ni and Au/Ni interfaces lie exactly in the plane of the interfaces, while the dislocations at Ag/NiO and Au/NiO interfaces reside at a stand-off distance, 3 to 4 (111)Ag or (111)Au interplanar spacings from the interfaces.

High-resolution imaging of the (111) Ag/Ni interface

1990 ◽  
Vol 48 (4) ◽  
pp. 368-369
Author(s):  
Y. Gao ◽  
K. L. Merkle
Keyword(s):  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Special Technique ◽  
Misfit Dislocations ◽  
Metal Composite ◽  
Coherent Interface ◽  
Embedded Atom ◽  
Resolution Electron ◽  
Metal Metal ◽  
Resolution Imaging

Computer simulations of Ag/Ni interfaces using embedded atom potentials have predicted that the interfacial energy of the (111) Ag/Ni interface is lowest. However, the semi-coherent interface configuration implied by these calculations has not been confirmed by experimental observation. It is well known that in heterophase systems with small misfit, the misfit is accommodated by misfit dislocations at the interface, forming a semi-coherent interface. However, it is not clear whether or not and to what degree misfit localization will occur at the interfaces with as large a misfit as 14% (Ag/Ni interface). The purpose of this investigation was to examine the atomic structure of the (111) Ag/Ni interface by high-resolution electron microscopy (HREM) and to compare the result to calculated images based on relaxed and rigid models.Metal-metal composite thin films of Ni particles in a Ag matrix were produced by epitaxial growth on (110) NaCl substrates using a special technique described in detail elsewhere. HREM observations were performed using H-9000 at a Northwestern University operated at 300 kV. The images were obtained near optimum defocus without objective aperture. All image simulations were carried out using the multislice method with EMS program package.

HIGH RESOLUTION ELECTRON MICROSCOPE STUDY OF CdTe-Cd0.6Mn0.4 Te SUPERLATTICES

1985 ◽  
Vol 56 ◽  
Author(s):  
C. CHOI ◽  
N. OTSUKA ◽  
L. A. KOLODZIEJSKI ◽  
R. L. GUNSHOR-a
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Phase Contrast ◽  
Electron Microscope Study ◽  
Lattice Mismatch ◽  
Thick Layer ◽  
High Resolution Electron Microscopy ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
High Resolution Electron Microscope

AbstractStructures of CdTe-Cd0.6Mn0.4Te superlattices which are caused by the lattice mismatch between suterlattice layers have been studied by high resolution electron microscopy (HREM). In thin-layer superlattices, the crystal lattice in each layeris elastically distorted, resulting in the change of the crystal symmetry from cubic to rhombohedral. The presence of the small rhombohedral distrotion has been confirmed through a phase contrast effect in HREM images. In a thick-layer superlattice, the lattice mismatch is accommodated by dissociated misfit dislocations. Burgers vectors of partial misfit dislocations have been identified from the shift of lattice fringes in HREM images.

High-resolution electron microscopy of epitaxial YBCO/Y2O3/YSZ on Si(001)

1993 ◽  
Vol 8 (9) ◽  
pp. 2112-2127 ◽  
Author(s):  
A. Bardal ◽  
O. Eibl ◽  
Th. Matthée ◽  
G. Friedl ◽  
J. Wecker
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Thick Layer ◽  
Atomic Layer ◽  
High Resolution Electron Microscopy ◽  
Stacking Fault ◽  
Buffer Layers ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
Unit Cells

The microstructures of YBa2Cu3O7−δ (YBCO) thin films grown on Si with Y-stabilized ZrO2 (YSZ) and Y2O3 buffer layers were characterized by means of high-resolution electron microscopy. At the Si–YSZ interface, a 2.5 nm thick layer of regrown amorphous SiOx is present. The layer is interrupted by crystalline regions, typically 5 to 10 nm wide and 10 to 50 nm apart. Close to the crystalline regions, {111} defects are present in the Si substrate. The typical defect observed is an extrinsic stacking fault plus a perfect dislocation close to the stacking fault which terminates extra {111} planes in the upper part of the Si. These defects are probably formed by condensation of Si self-interstitials created during oxide regrowth. Precipitates are present in the Si close to the Si–YSZ interface and indicate that in-diffusion of Zr has occurred. The YSZ–Y2O3 interface is atomically sharp and essentially planar and contains no second phases. Perfect misfit dislocations with Burgers vector 1/2〈110〉 are present at this interface along with unrelaxed elastic misfit stresses. The Y2O3–YBCO interface is atomically sharp and planar, but contains steps. (001) stacking faults are present in the YBCO above these steps; the faults are, however, healed a few unit cells away from the interface. By HREM analysis of ultrathin specimen areas, the atomic layer of the YBCO closest to the Y2O3 was found to be a barium-oxygen layer.

High resolution electron microscopy of misfit dislocations in the GaAs/Si epitaxial interface

1986 ◽  
Vol 49 (5) ◽  
pp. 277-279 ◽  
Author(s):  
N. Otsuka ◽  
C. Choi ◽  
Y. Nakamura ◽  
S. Nagakura ◽  
R. Fischer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
Epitaxial Interface

Transmission electron microscopy study of Co/Pd and Co/Au multilayers

1993 ◽  
Vol 8 (5) ◽  
pp. 1019-1027 ◽  
Author(s):  
F. Hakkens ◽  
A. De Veirman ◽  
W. Coene ◽  
Broeder F.J.A. den
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Columnar Structure ◽  
Electron Microscopy Study ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Resolution Electron

The structure of Co/Pd and Co/Au (111) multilayers is studied using transmission electron microscopy and high resolution electron microscopy. We focused on microstructure, atomic stacking (especially at the interfaces), and coherency, as these are structural properties that have considerable magnetic effects. A columnar structure with a strong curvature of the multilayer influenced by substrate temperature during growth is observed. High resolution imaging shows numerous steps at the interfaces of the multilayer structure and the presence of misfit dislocations. In bright-field images, periodic contrast fringes are observed at these interfaces as the result of moiré interference. These moiré fringes are used to study the misfit relaxation at the interfaces, whereas electron diffraction gives the average relaxation over the whole layer. Both measurements determined that, for Co/Pd as well as Co/Au multilayers, 80–85% of the misfit is relaxed and 20–15% remains in the form of strain, independent of the Co layer thickness in the regime studied.

Atomic Structure of Interfaces: Link of Atomistic Calculations with High Resolution Electron Microscopy

1998 ◽  
Vol 4 (S2) ◽  
pp. 762-763
Author(s):  
V. Vitek
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Computer Modeling ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Interfacial Structure ◽  
Embedded Atom ◽  
Resolution Electron ◽  
Atomic Interactions ◽  
Atomistic Calculations

Since interfaces and grain boundaries affect critically many properties of materials, their atomic structure has been investigated very extensively using computer modeling. Most of these calculations have been made using semi-empirical central-force descriptions of atomic interactions, recently primarily the embedded-atom type many-body potentials. Owing to the approximate nature of such schemes, a connection with experimental observations that can validate the calculations is essential. The high resolution electron microscopy (HREM) is such experimental technique and it has, indeed, been frequently combined with calculations of interfacial structure and chemistry. In fact such a link is not only important for verification of the results of computer modeling but also crucial for meaningful interpretation of HREM observations. Hence, coupling the atomistic modeling with HREM is a synergistic procedure. It not only leads to better understanding of interfacial structures but may contribute significantly to the validation and assessment of limits of the schemes used for the description of atomic interactions.

High-Resolution Electron Microscopy of Olivine-Magnetite Interfaces

1989 ◽  
Vol 159 ◽  
Author(s):  
Stuart Mckernan ◽  
C. Barry Carter ◽  
Daniel Ricoult ◽  
A. G. Cullis
Keyword(s):  
Electron Microscopy ◽  
Phase Transitions ◽  
High Resolution ◽  
Mass Transport ◽  
High Resolution Electron Microscopy ◽  
Model System ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
Lattice Images

ABSTRACTThe oxidation of iron-rich olivine to produce magnetite is a model system for the study of phase transitions involving mass transport. High-resolution lattice images of have been obtained from magnetite precipitates in naturally modified iron-rich olivines. The magnetite/olivine interface is shown to be extremely sharp. Steps and misfit dislocations are present at the interface.

Relaxation of Metamorphic III-V Heterostructures Studied by Digital Processing of HREM Images

1998 ◽  
Vol 523 ◽  
Author(s):  
André Rocher ◽  
Etienne Snoeck ◽  
Léon Goldstein ◽  
Joël Jacquet ◽  
Catherine Fortin
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Transition Zone ◽  
Epitaxial Layer ◽  
Digital Processing ◽  
High Resolution Electron Microscopy ◽  
Dislocation Network ◽  
Misfit Dislocations ◽  
Misfit Stress ◽  
Resolution Electron

AbstractThe crystalline structure of metamorphic heterostructures grown by epitaxy has been studied by digital processing of High Resolution Electron Microscopy (HREM) images. Two systems have been investigated: the GaSb/(001)GaAs, known to be fully relaxed by a perfect Lomer dislocation network and the GaAs/(001)InP relaxed by partial and 60° dislocations randomly distributed. A transition zone can be defined between the perfect substrate and the relaxed epitaxial layer: its thickness is less than 20Å in GaSb/GaAs and more than 80Å in GaAs/InP. These results indicate that the misfit dislocations are only one of the elements involved in the relaxation of misfit stress.

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