What is EBSD?
Developing new materials, plus increasing their accessibility and affordability, drives technological and economic advances in our world. Materials scientists study the interplay between a material’s structure, processing steps, and critical properties to optimize its performance for any given application. Material characterization lies at the heart of these studies, and electron microscopy characterization is often the best tool for atomic- to micro-scale analysis.
Electron backscatter diffraction (EBSD) is a key analytical tool for characterizing the crystallographic microstructure in material and earth sciences. The EBSD technique uses a scanning electron microscope to gather statistical data on grain size, orientation, grain boundary character, and texture, which are critical parameters in determining the mechanical properties of crystalline materials.
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The backscattered electrons used for EBSD analysis originate from the first few nanometers below the sample surface. This can at times make EBSD analysis complicated, as it requires a specimen with a near-perfect surface, e.g., with little or no damage. By having a pristine crystal lattice within this near-surface volume, it produces high-quality EBSD diffraction patterns. Gatan enables proper EBSD analysis by providing broad argon beam tools that easily and reproducibly prepare nearly damage-free scanning electron microscopy (SEM) sample surfaces. Additionally, any remaining damage can be correctly associated with the underlying stage of the material to give insight into the strain and deformation present in the material of interest. Moreover, Gatan’s broad argon beam tools are useful to prepare samples for EBSD from metals, ceramics, semiconductors, and minerals.
|Crystal orientation||Grain size|
|Local and global texture||Recrystallize/deformed fractions|
|Substructure and strain analysis||Grain boundary characterization|
|Phase identification, distribution, and transformations||Fracture analysis|
Metals and Alloys
Metals form the backbone of our world. Metals are generally strong and deformable, resulting in their use as structural materials in various applications. Metals are also good conductors of electricity and are used as connection materials in microelectronic circuits. Often, multiple elements are mixed to form an alloy, and these mixtures form compositions and phases that have improved properties compared to pure metal. Metals are also shaped for different applications, and this processing affects both the material’s microstructure and properties.
EBSD can improve the ductility of magnesium alloys to be used more frequently and economically in automotive applications or identify the crystallographic texture that develops in a microelectronic device to improve the lifetime. This characterization information is necessary to ensure that metals provide the required properties for a given application and develop new metals for new applications and industries.
Understanding a mineral requires both knowing the crystal structure and chemistry of the mineral. Combining crystallographic data obtained with EBSD with chemical data acquired simultaneously with energy dispersive spectroscopy (EDS) improves the characterization of the phases with geological samples, how they are distributed, and the understanding of the processes involved in the formation of the material.
With orientation imaging microscopy (OIM), we can truly look at the material microstructures and properties then link them to the pressure and temperatures that something formed at or how their material properties change as pressure and temperature conditions change. With the knowledge gained from microanalysis, one can understand how materials react on the atomic scale to understand deformation, on the planetary scale to understand how a planet was formed, and many other processes.
Renewable energy, produced from renewable resources such as solar radiation, wind, water currents, and geothermal heat, is a fast-growing industry. There are many materials-based problems within the renewable energy sector that researchers are generally seeking to boost efficiency, lower cost, possibly weight, or utilize some previously under-utilized resource. One area of renewable energy is photovoltaics (PV), which are materials that absorb and convert solar radiation into useable electrical power. Photovoltaics are specialized semiconductor materials, while the complete photovoltaic assemblies are generally multi-layer devices comprised of electrical contact layers and other layers to optimize performance or protect the device from environmental exposure. Recently, hybrid organic-inorganic perovskite has generated significant interest due to its combination of optoelectronic properties and low cost of fabrication.
Analysis techniques, such as EBSD, are essential in enabling researchers to understand the crystallographic structure of materials and how they can be modified to maximize performance and minimize cost. Specific characteristics such as composition, layer thickness, grain size, and microstructure have tremendous impacts on the quality and efficiency of solar products. Microanalysis techniques are used to study microstructural characteristics and refine the recipes and processes to optimize photovoltaic materials.
Another promising technology is fuel cells. A fuel cell is an electrochemical cell that converts energy from fuel, hydrogen molecules into electrical energy. Electricity is generated from the reaction between a fuel supply and an oxidizing agent. A wide variety of materials are used to achieve optimal and reliable performance. The grain microstructure can be studied with EBSD.
Step 1: Specimen preparation
Specimens must be prepared carefully for EBSD applications, as the technique requires a very smooth specimen surface to avoid shadows on the diffraction pattern. The best way to accomplish this is to utilize a fully automated argon ion polishing system, like the PECS II instrument.
Using a PECS II instrument can produce damage-free surfaces, cross-sections, and deposit coatings to protect or eliminate charging.
Step 2: Data collection
EBSD detectors collect maps containing diffraction patterns of the sample from a user-defined area, and these patterns are indexed to determine the local crystal structure and orientation. EBSD can also be combined with related techniques, such as energy dispersive spectroscopy (EDS), to further understand the material’s composition.
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Step 3: Analyze
Several powerful post-processing analysis techniques are possible with EBSD. EBSD maps can be generated from the raw data to provide information on the orientation, phase distribution, grain size and shape, grain boundary structure, and local deformation of crystallographic microstructures. This information helps users visualize, characterize, understand, and communicate the details of their material’s microstructure.
Visit EDAX.com for more information on EBSD analysis software.
- Broad Argon Ion Beam Tool for EBSD Preparation Webinar
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