Fabrication of hexagonal MgO and its precursors by a homogeneous precipitation method

The platelet-like and assembled hexagonal Mg5(CO3)4(OH)2·4H2O have been prepared via a homogenous precipitation reaction between MgCl2 and (CH2)6N4. The pH variation of initial solutions results in different nucleation rates, which further leads to various morphology changes from platelets to assembled structures. The similar morphology of magnesium oxide (MgO) samples can be obtained by calcination of their corresponding Mg5(CO3)4(OH)2·4H2O samples. In addition, the novel self-assembled MgO crystals with a flowerlike morphology have been obtained by calcination of MgO precursor, which is synthesized via a homogenous precipitation reaction between MgCl2 and CO(NH2)2. A possible self-assembly process of flowerlike crystals is proposed by arresting a series of intermediate morphologies during the shape evolution from the submicrometer-sized petal to the flowerlike morphology.