title: Structure refinement from precession electron diffraction data.
abstract: Electron diffraction is a unique tool for analysing the crystal structures of very small crystals. In particular, precession electron diffraction has been shown to be a useful method for ab initio structure solution. In this work it is demonstrated that precession electron diffraction data can also be successfully used for structure refinement, if the dynamical theory of diffraction is used for the calculation of diffracted intensities. The method is demonstrated on data from three materials - silicon, orthopyroxene (Mg,Fe)(2)Si(2)O(6) and gallium-indium tin oxide (Ga,In)(4)Sn(2)O(10). In particular, it is shown that atomic occupancies of mixed crystallographic sites can be refined to an accuracy approaching X-ray or neutron diffraction methods. In comparison with conventional electron diffraction data, the refinement against precession diffraction data yields significantly lower figures of merit, higher accuracy of refined parameters, much broader radii of convergence, especially for the thickness and orientation of the sample, and significantly reduced correlations between the structure parameters. The full dynamical refinement is compared with refinement using kinematical and two-beam approximations, and is shown to be superior to the latter two.
authors: Institute of Physics of the AS CR, v.v.i., Na Slovance 2, 182 21 Prague, Czech Republic. palat@fzu.cz
authors: Lukáš
authors: L
authors: Palatinus
authors: Damien
authors: D
authors: Jacob
authors: Priscille
authors: P
authors: Cuvillier
authors: Mariana
authors: M
authors: Klementová
authors: Wharton
authors: W
authors: Sinkler
authors: Laurence D
authors: LD
authors: Marks
keywords: dynamical diffraction; orthopyroxene; precession electron diffraction; site occupancy