EXPERIMENTAL AND THEORETICAL CHARACTERIZATION OF KAOLINITE BY DFT, XANES AB INITIO SIMULATIONS, AL K XANES AND SI K XANES/EXAFS

M. MIZRAHI; N. RENDTORFF; D. RICHARD; L. ANDRINI

Campinhas

Congreso; 29th RAU- Reunion Anual de Usuarios LNLS; 2019

LNLS

Kaolinite (Al2O3·2SiO2·4H2O) is classified as a 1:1 dioctahedral phyllosilicate and it is the main componentof the kaolin group of minerals. The importance of kaolinitic clays in the development of modern ceramicscience can best be appreciated by considering its widespread influence on ceramic, material science, andmineralogy. These clays have been widely used in different technological applications for thousands of years[1]. Its technological importance requires an exhaustive study of its morphological nature as an electronicstructure. In a recent paper [2] a detailed first principles study of the bulk structure of kaolinite was carriedout, and the predictions solve previous controversies around kaolinite bulk structure. In this work we extendthe theoretical aspects, to introduce the structures generated by DFT-calculus in the FEFF, FDMNES andSPR-KKR programs to simulate the absorption spectra in the K edge of the Al and Si, correlating theseresults with the experimental data obtained in the SXS-beamline (LNLS, Campinas, SP, Brazil). In addition,Si K EXAFS spectra were obtained for kaolinites with different degrees of crystallinity and distortions. Thisallows to make adjustments of the EXAFS signal and its corresponding Fourier transform, and compare withthe models obtained by DFT. In this meeting we present the advances of this research.