Probing the thermal decomposition process of layered double hydroxides through in situ 57Fe Mo¨ ssbauer and in situ X-ray diffraction experiments

The thermal decomposition properties of Mg–Fe hydrotalcites were studied through in situ 57Fe Mo¨ ssbauer spectroscopy and in situ X-ray diffraction. Abrupt changes in the quadrupolar splitting measured in the Mo¨ ssbauer spectra revealed a phase transition from the starting lamellar structure to a new crystalline arrangement. By analyzing the Mo¨ ssbauer parameters we show that the material is highly disordered in the 300–400 C temperature range. This hypothesis is confirmed by the X-ray results whose diffractograms indicated the collapse of the lamellar structure and the formation of a solid solution.