Solution decomposition of the layered double hydroxide (LDH) of Zn with Al

The layered double hydroxides (LDH) of Zn with Al containing intercalated CO32- and NO3- ions undergo solution decomposition to yield a highly crystalline oxide mixture comprising ZnO and ZnAl2O4 at temperatures as low as 150-180 degrees C under hydrothermal conditions. In contrast solid-state decomposition takes place at a much higher temperature (240-315 degrees C) in air. Solution decomposition is not only guided by the low octahedra crystal field stabilization energy of Zn2+ ions, a factor that also affects solid-state decomposition, but also by solubility considerations. The LDHs of Mg and Ni with Al do not undergo solution decomposition.