Toward Realizing the Structure-Property Link in Polycrystalline Thin Films

1994 ◽  
Vol 343 ◽  
Author(s):  
C. S. Nichols
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Coincidence Site Lattice ◽  
Polycrystalline Materials ◽  
Structure Property ◽  
New Approach ◽  
Site Lattice ◽  
Polycrystalline Thin Films ◽  
Structures And Properties ◽  
Polycrystalline Form

ABSTRACTMany materials for engineering applications are used in polycrystalline form and contain grain boundaries with a range of structures and properties. However, most research on grain boundaries to date has focussed exclusively on symmetric coincidence site lattice interfaces. To go beyond descriptions for these simple interfaces and thence to an aggregate of grains and grain boundaries in a polycrystal will require a new approach. Here we discuss two models for properties of polycrystalline materials, including their advantages and drawbacks, and indicate the microstructural variables available to optimize properties.

Electron diffraction studies of amorphous and polycrystalline thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 118-119
Author(s):  
D J H Cockayne ◽  
D R McKenzie
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Polycrystalline Materials ◽  
Good Resolution ◽  
Scattered Intensity ◽  
Radial Density ◽  
X Ray ◽  
Polycrystalline Thin Films ◽  
Nitrogen Ion ◽  
Diffraction Patterns

The study of amorphous and polycrystalline materials by obtaining radial density functions G(r) from X-ray or neutron diffraction patterns is a well-developed technique. We have developed a method for carrying out the same technique using electron diffraction in a standard TEM. It has the advantage that studies can be made of thin films, and on regions of specimen too small for X-ray and neutron studies. As well, it can be used to obtain nearest neighbour distances and coordination numbers from the same region of specimen from which HREM, EDS and EELS data is obtained.The reduction of the scattered intensity I(s) (s = 2sinθ/λ ) to the radial density function, G(r), assumes single and elastic scattering. For good resolution in r, data must be collected to high s. Previous work in this field includes pioneering experiments by Grigson and by Graczyk and Moss. In our work, the electron diffraction pattern from an amorphous or polycrystalline thin film is scanned across the entrance aperture to a PEELS fitted to a conventional TEM, using a ramp applied to the post specimen scan coils. The elastically scattered intensity I(s) is obtained by selecting the elastically scattered electrons with the PEELS, and collecting directly into the MCA. Figure 1 shows examples of I(s) collected from two thin ZrN films, one polycrystalline and one amorphous, prepared by evaporation while under nitrogen ion bombardment.

scholarly journals A Tool for Local Thickness Determination and Grain Boundary Characterization by CTEM and HRTEM Techniques

2015 ◽  
Vol 21 (2) ◽  
pp. 422-435 ◽  
Author(s):  
Ákos K. Kiss ◽  
Edgar F. Rauch ◽  
Béla Pécz ◽  
János Szívós ◽  
János L. Lábár
Keyword(s):  
Grain Boundaries ◽  
Software Tool ◽  
Hexagonal Crystal ◽  
Electron Microscopic ◽  
Orientation Data ◽  
New Approach ◽  
Polycrystalline Thin Films ◽  
Transmission Electron ◽  
Transmission Electron Microscopic

AbstractA new approach for measurement of local thickness and characterization of grain boundaries is presented. The method is embodied in a software tool that helps to find and set sample orientations useful for high-resolution transmission electron microscopic (HRTEM) examination of grain boundaries in polycrystalline thin films. The novelty is thesimultaneoustreatment of the two neighboring grains and orienting both grains and the boundary planesimultaneously. The same metric matrix-based formalism is used for all crystal systems. Input into the software tool includes orientation data for the grains in question, which is determined automatically for a large number of grains by the commercial ASTAR program. Grain boundaries suitable for HRTEM examination are automatically identified by our software tool. Individual boundaries are selected manually for detailed HRTEM examination from the automatically identified set. Goniometer settings needed to observe the selected boundary in HRTEM are advised by the software. Operation is demonstrated on examples from cubic and hexagonal crystal systems.

Predictive Structure-Property Correlations for SrtiO3 Grain Boundaries

2001 ◽  
Vol 7 (S2) ◽  
pp. 292-293
Author(s):  
Pradyumna L. Prabhumirashi ◽  
Kevin D. Johnson ◽  
Vinayak P. Dravid
Keyword(s):  
Grain Boundaries ◽  
Electrical Transport ◽  
Current Control ◽  
Polycrystalline Materials ◽  
Structure Property ◽  
Electrical Transport Properties ◽  
Potential Barriers ◽  
Impurity Segregation ◽  
Direct Observations ◽  
Internal Potential

In polycrystalline materials the trapping of charge at interfaces has a decisive influence on the electrical transport properties through the formation of electrostatic potential barriers. This can either be an intrinsic phenomenon or can be related to impurity segregation leading to complex defect centers. This plays a key role in technologically important systems, especially those having electrically active interfaces, e.g.,p-n junctions in semiconductors and grain boundaries in electroceramics.Electroceramic oxides such as ZnO and SrTiO3 are common systems that exhibit the tendency of current control by internal potential barriers. While bulk measurements, either electrical (e.g. P-E, C-V, I-V), or optical (e.g. Raman) have contributed significantly to the understanding of charged interfaces, there are a very few direct observations of electrical activity at a nanometer level. For instance, it has been recognized that space charge and dopant segregation at the grain boundary are inter-related.

The Morphology of Grain Boundary Interactions with Twins in YBa2Cu3O7−δ

1993 ◽  
Vol 319 ◽  
Author(s):  
Jenn-Yue Wang ◽  
A. H. King
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Twin Boundary ◽  
Interfacial Energy ◽  
Coincidence Site Lattice ◽  
The Other ◽  
Twin Boundaries ◽  
Site Lattice ◽  
Dislocation Arrays

AbstractVarious morphologies are observed where twins meet grain boundaries in YBa2Cu3O7−δ. Twins may be “correlated” at the boundary (i.e. twin boundaries from one grain may meet a twin boundary from the other grain in a quadruple junction) and the twins may be narrowed or “constricted” at the boundary. These effects are determined by the interfacial energy. We estimate the energy of the various interfaces by determining the dislocation arrays they contain, using the constrained coincidence site lattice (CCSL) model and Bollmann's O2-lattice formalism. Our approach indicates that there are significant changes in the energy of the interfaces and is thus able to explain the variety of observed morphologies.

In-Plane Orientation and Coincidence Site Lattice Relation of Bi2Sr2CaCu2Ox Thin Films Formed on Highly Mismatched (001) YAG Substrates

1993 ◽  
Author(s):  
Masayuki KATAOKA ◽  
Ken'ichi KURODA ◽  
Tetsuya TAKAMI ◽  
Toshiyuki OISHI ◽  
Junji TANIMURA ◽  
...  
Keyword(s):  
Thin Films ◽  
Coincidence Site Lattice ◽  
Site Lattice ◽  
Plane Orientation
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