Direct Formation of Mg?Al-Layered Double-Hydroxide Films on Glass Substrate by the Sol?Gel Method With Hot Water Treatment

Abstract

Amorphous Al2O3–MgO thin films with an Mg/Al ratio of unity were prepared on glass substrates by the sol–gel method with a heat treatment at 300°C for 30 min. By immersing the films in water containing sodium hydroxide (pH 10–13) at 100°C, nano-crystals of Mg–Al-layered double hydroxide (LDH) with a hexagonal structure, which is called hydrotalcite and the most basic composition of LDH, were precipitated on the amorphous Al2O3–MgO films. The maximum amount of Mg–Al nanocrystals was obtained when the film was immersed in basic solution of pH 12.