Electron crystallographic study of a kaolinite single crystal: Fid-Bau Portal

Electron crystallographic study of a kaolinite single crystal

Cora, Ildikó / Dódony, István / Pekker, Péter

Abstract 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)°.

Highlights • 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.