Effect of temporal pH variation of the reaction mixture on Mg(OH)2 morphology precipitated from an aqueous Mg(NO3)2-NaOH system

To understand the impact of temporal pH variation on the crystallisation process, Mg(OH)2 was synthesized via wet precipitation route from an aqueous Mg(NO3)2-NaOH system. A detailed analysis of morphological evolution and the nano-structural transformation was carried out to model the crystallisation process. Interestingly, low supersaturation at low pH level lying between 9.2 and 9.4 of the reaction mixture, was found to promote the growth of nanorod like 1-D structures. On the contrary, enhanced supersaturation created a chemical driving force favouring an edgewise growth of the nucleated primary nanocrystals along (101) and (110) crystallographic planes, which resulted in lamellar hexagonal nanostructures. The lamellar growth demonstrated an increment in the particle size and reduction in anisotropic strain and dislocation density due to proper nucleation in the samples. Such controlled growth and nucleation of the Mg(OH)2 morphology presents a great scope of potential applications of this material.