Evaluation of accuracy in the determination of crystal structure factors using large-angle convergent-beam electron diffraction patterns

Daisuke Morikawa; Kenji Tsuda

doi:10.1093/jmicro/dfaa041

Evaluation of accuracy in the determination of crystal structure factors using large-angle convergent-beam electron diffraction patterns

Microscopy (Oxf). 2021 Mar 24;70(2):178-185. doi: 10.1093/jmicro/dfaa041.

Authors

Daisuke Morikawa¹, Kenji Tsuda²

Affiliations

¹ Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan.
² Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Aramaki aza Aoba 6-3, Aoba-ku, Sendai 980-8578, Japan.

PMID: 32691038
DOI: 10.1093/jmicro/dfaa041

Abstract

The accuracy of electron density distribution analysis using large-angle convergent-beam electron diffraction (LACBED) patterns is evaluated for different convergence angles. An orbital ordered state of FeCr2O4 is used as an example of the analysis. Ideal orbital-ordered and non-ordered states are simulated by using orbital scattering factors. LACBED patterns calculated for the orbital-ordered state were used as hypothetical experimental data sets. Electron density distribution of the Fe 3d orbitals has been successfully reconstructed with a higher accuracy from LACBED patterns with convergence angles larger than 15.2 mrad, which is 4 times as large as that for conventional convergent-beam electron diffraction patterns. Excitation of particular Bloch waves with the aid of LACBED patterns has a key role in the accurate analysis of electron density distributions.

Keywords: convergent-beam electron diffraction; crystal structure factor; electrostatic potential analysis; large-angle rocking; orbital scattering factor; orbital-ordered state.