Thermal decomposition of Mg Al and Mg Ga layered-double hydroxides: a spectroscopic study

An Mg/Al and a Mg/Ga layered double hydroxide (LDH) were synthesized by usi ng the coprecipitation method and calcined at a variety of temperatures. Th e starting LDHs and their calcination products (mixtures of oxides and spin els) were characterized by X-ray diffraction, solid-state NMR and IR spectr oscopies and thermogravimetric analysis. Based on the results, the LDHs stu died possess a brucite-like structure where tervalent cations occupy octahe dral positions. At moderate temperatures, calcination gives a mixture of ox ides; at high temperatures, however, the corresponding spinels are obtained .