The double hydroxide of Al with Li: mechanism of formation and reversible thermal behavior

All the polymorphic modifications of Al(OH)3 and the oxide–hydroxide of Al, boehmite, on hydrothermal treatment in Li+ containing solutions transform into the layered double hydroxide of Al with Li having the nominal composition [LiAl2(OH)6](CO3)1/2·1.5H2O, suggesting that these compounds form via a dissolution–reprecipitation mechanism. The oxide residue obtained by the thermal decomposition of this layered double hydroxide also partially reconstructs the layered double hydroxide on soaking in water lending further evidence to the dissolution–reprecipitation mechanism. Under hydrothermal conditions, in water, the layered double hydroxide undergoes delithiation to yield aluminum hydroxide phases other than gibbsite, suggesting again that delithiation too proceeds by a dissolution–reprecipitation mechanism.