Direct Observation of a Metastable Solid Phase of Mg/Al/CO3-Layered Double Hydroxide by Means of High Temperature in Situ Powder XRD and DTA/TG

In situ XRD measurement of Mg/Al-layered double hydroxide at high temperature reveals that the hydrotalcite-like layered structure, which is stable at room temperature, thermally transforms to a metastable solid phase at 160−200 °C, depending atomic ratio Mg/Al of the layers. This metastable phase has smaller interlayer distance than that of the hydrotalcite-like layered structure and usually disappears at 380 °C. These thermal events are confirmed in DTA/TG measurements.