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Study of temperature factors in cubic crystals by high-voltage electron diffraction
S Matsumura1, Y Tomokiyo, K Oki
1Department of Materials Science and Technology, Graduate School of Engineering Sciences, Kyushu University, Fukuoka, Japan.
Journal of Electron Microscopy Technique
|July 1, 1989
Summary
Atomic temperature factors in cubic crystals were studied using critical voltage measurements. Anharmonic vibrations significantly impact metals like Al and Cu, unlike Si and Ge.
Area of Science:
- Solid-state physics
- Materials science
- Crystallography
Background:
- Atomic temperature factors describe atomic vibrations in crystals.
- Critical voltage measurements in electron microscopy offer insights into these factors.
- Understanding atomic vibrations is crucial for predicting material properties.
Purpose of the Study:
- To investigate atomic temperature factors in cubic crystals.
- To determine the influence of anharmonic effects on atomic vibrations.
- To compare experimental results with theoretical models.
Main Methods:
- High-voltage electron microscopy was used to measure critical voltages for systematic reflections.
- Kikuchi line splitting was analyzed.
- Experimental data were compared with harmonic, quasi-harmonic, and anharmonic approximations.
Main Results:
- Silicon (Si) and Germanium (Ge) showed weak anharmonic contributions to atomic temperature factors.
- Aluminum (Al), Copper (Cu), and Iron (Fe) exhibited nonlinear temperature dependence, indicating significant anharmonic effects.
- The quasi-harmonic approximation accurately predicted results for Fe but not for Al and Cu.
Conclusions:
- Anharmonic atomic vibrations are crucial for understanding the temperature dependence of critical voltages in metals like Al and Cu.
- The study successfully estimated coefficients for isolated atom potentials, aligning with diffraction data.
- Critical voltage measurements provide a valuable method for probing anharmonicity in crystal lattices.