EXAFS AND XANES STUDY OF LAYERED DOUBLE HYDROXIDES

Structure of Layered Double Hydroxides and the reaction occurring duri ng thermal treatments are investigated. The reaction is supposed to be a grafting reaction of interlamellar species onto layers but its mech anism is not well known. These materials display a very poor level of organisation and the study of their fine structure involves the use of techniques sensitive to the local environments. XANES and EXAFS studi es give few information about the grafting process because of the grea t disorder in the interlayer space. Much more information about the la yers local structure are reached, revealing that distorted and regular octahedra coexist which is particular to layers containing copper ato ms. It probably creates a local segregation undetectable by X ray diff raction study in anyway. Tt also highlights the difference of sheet th ermal stability in function of the nature of the intercalated anion.