Structural Analysis of Defects in Layered Double Hydroxides and Related Mixed Oxides

Results of studying the structural defects in MgAl and NiAl layered double hydroxides and in the products of their thermal decomposition to 1000 degrees C, obtained over the last 10 years at the Laboratory of Analytical and Physicochemical Methods of Research, Institute of Hydrocarbons Processing, Siberian Branch, Russian Academy of Sciences, were reviewed. These studies were performed using the method of simulation of X-ray diffraction patterns for one-dimensionally (1D) disordered crystals. Changes in the type of the structural defects depending on the calcination temperature were revealed, in particular, via in situ X-ray diffraction. A structural mechanism of the formation of the dehydrated phase at T = 200 degrees C was proposed. New models of the MgAl and NiAl oxide structures were presented. The structures of the phases contained in the products of hydration of the oxides were established. The difference in the behavior of the oxides during hydration was explained.