Abstract: Superfine Mg(OH)₂particles were synthesized by hydration of MgO made from brucite calcination in CO(NH₂)₂ alkali solutions.The crystal phase,morphology and size distribution of the Mg(OH)₂ particles as prepared were characterized with X-ray(XRD) and scanning electron microscopy(SEM).The results indicated that the solution concentration and additive can remarkably affect the crystal phase and particle size.At a solution concentration of 2.5 mol/L and using PEG 6000 as an additive,the resultant superfine Mg(OH)₂particles exhibit a regular hexagonal platelet morphology and a narrow size distribution with an average radius of 250nm and thickness of 150 nm,but the purity of particles remains to be improved.

Key words: Magnesium hydroxide, Additive, Brucite, Hexagonal platelet