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 using the coprecipitation method and calcined at a variety of temperatures. The starting LDHs and their calcination products (mixtures of oxides and spinels) were characterized by X-ray diffraction, solid-state NMR and IR spectroscopies and thermogravimetric analysis. Based on the results, the LDHs studied possess a brucite-like structure where tervalent cations occupy octahedral positions. At moderate temperatures, calcination gives a mixture of oxides; at high temperatures, however, the corresponding spinels are obtained.