Experimental and theoretical characterization of kaolinite by DFT, XANES ab initio simulations, Al K XANES and Si K XANES/EXAFS

DIEGO RICHARD; MARTÍN MIZRAHI; NICOLÁS M. RENDTORFF; LEANDRO ANDRINI

Campinas

Otro; Annual Users Meeting LNLS/CNPEM; 2019

Brazilian Synchrotron Light Laboratory

Kaolinite(Al2O3·2SiO2·4H2O) is classified as a 1:1 dioctahedral phyllosilicateand it is the main component of the kaolin group of minerals. The importance ofkaolinitic clays in the development of modern ceramic science can best be appreciated by considering itswidespread influence on ceramic, material science, and mineralogy. These clays have been widely used indifferent technological applications for thousands of years. Its technologicalimportance requires an exhaustive study of its morphological nature as anelectronic structure. In a recent paper [2] a detailed firstprinciples study of the bulk structure of kaolinite was carried out, and the predictions solve previous controversiesaround kaolinite bulk structure. In this work we extend the theoretical aspects, to introduce the structuresgenerated by DFT-calculus in the FEFF, FDMNES and SPR-KKR programs to simulate the absorption spectra inthe K edge of the Al and Si, correlating these results with the experimental data obtained in theSXS-beamline (LNLS, Campinas, SP, Brazil). In addition, Si K EXAFS spectra were obtained for kaolinites withdifferent degrees of crystallinity and distortions. This allows to make adjustments of the EXAFS signal and itscorresponding Fourier transform, and compare with the models obtained by DFT. In this meeting we presentthe advances of this research.