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Charge density determination in icosahedral AlPdMn quasicrystal using quantitative convergent beam electron
Fengmei Yu1, Huamin Zou, Jianbo Wang
1Department of Physics, Wuhan University, Wuhan 430072, China.
Micron (Oxford, England : 1993)
|May 4, 2004
Summary
Quantitative convergent beam electron diffraction (QCBED) revealed charge density distribution in AlPdMn quasicrystals. Identical atoms exhibited varying valences, with localized bonding charge along specific directions.
Area of Science:
- Materials Science
- Solid-State Physics
- Crystallography
Background:
- Icosahedral quasicrystals like AlPdMn possess complex atomic structures.
- Understanding charge density distribution is crucial for explaining their unique properties.
Purpose of the Study:
- To investigate the charge density distribution in an icosahedral AlPdMn quasicrystal.
- To refine structure factors and construct a bonding charge density map.
Main Methods:
- Quantitative convergent beam electron diffraction (QCBED) on a single-crystal specimen.
- Wave-mechanical formulation of electron diffraction dynamical theory for intensity calculations.
- Iterative refinement of structure factors using experimental data.
Main Results:
- Refined structure factors for nine strongest symmetry inequivalent reflections.
- Transformed electron structure factors to X-ray structure factors using the Mott formula.
- Constructed a bonding charge density map, revealing localized bonding charge.
Conclusions:
- Identical atoms in the quasicrystal can possess different valences depending on their positions.
- The study provides insights into the electronic structure and bonding characteristics of quasicrystals.