Characterisation of layered double hydroxides and their decomposition products

A review on recent results on characterisation of layered double hydroxides (LDHs) prepared by conventional coprecipitation methods is reported. Emphasis is made on the application of few experimental methods for characterising structural properties of these compounds. The use of powder X-ray diffraction, X-ray absorption, MAS-NMR, and FT-IR spectroscopies to characterise particular properties of these solids is described. Thermal analyses (thermogravimetric, differential thermal analysis and temperature-programmed reduction) are used, together with other techniques, to characterise LDHs and mixed oxides produced by thermal decomposition of LDHs. Partial or total reconstruction of the layered structure from medium-temperature calcined LDHs is achieved depending on the calcination temperature and the time of exposure to water vapour.