Electron crystallographic study of a kaolinite single crystal

• We applied new techniques of electron crystallography for structure determination.
• The structure of kaolinite single crystal was determined and refined.
• The structure of the studied kaolinite is described in the non-conventional C1 sg.
• Single crystal structure determination of submicron-sized clay minerals is attainable.

Kaolinite is an abundant micro- and submicrometer-sized sheet silicate [Al2Si2O5(OH)4] built up of alternating tetrahedral (T) and octahedral (O) sheets. Except for Neder et al.'s (1999) single-crystal synchrotron study, X-ray and neutron diffraction methods were used for structural measurements on powdered samples. The aim of the present work is to provide a second single crystal structure determination on a kaolinite using recently developed electron diffraction techniques of electron crystallography.Using precession electron diffraction (PED, Vincent and Midgley, 1994; Avilov et al., 2007) and electron-diffraction tomography (Kolb et al., 2007, 2008) techniques, a 3D diffraction data set was acquired. The crystal structure was determined in SIR2011 and refined in SHELXL97 software. The crystal structure of the studied kaolinite is described in the non-conventional C1 space group with unit cell parameters: a = 5.21(1) Å, b = 9.12(2) Å, c = 7.48(2) Å, α = 88.7(2)°, β = 104.2(2)°, γ = 90.3(2)°.