Sample interview questions: How do you approach analyzing the crystal defects using transmission electron microscopy?
Sample answer:
Analysis of Crystal Defects Using Transmission Electron Microscopy (TEM)
- Sample Preparation: Prepare ultra-thin specimens (typically <100 nm thick) by mechanical polishing or focused ion beam (FIB) milling.
- Imaging: Use TEM imaging modes such as bright-field, dark-field, and high-resolution (HR) TEM to visualize crystal defects. HR-TEM provides atomic-scale resolution for detailed defect analysis.
- Electron Diffraction: Perform electron diffraction to obtain information about the crystal structure, lattice orientation, and presence of defects.
- Defect Identification: Identify crystal defects based on their morphology, diffraction patterns, and contrast mechanisms. Common defects include point defects (e.g., vacancies, interstitials), line defects (e.g., dislocations), and planar defects (e.g., grain boundaries, stacking faults).
- Quantitative Analysis: Measure defect parameters such as size, density, and distribution using image processing techniques.
- Elemental Analysis:… Read full answer
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