Magnesium hydroxide nanoparticles were synthesized in one step via  bubbling gaseous ammonia into magnesium chloride solution without any modification. The samples were characterized with scanning electron microscope (SEM)

X-ray powder diffraction (XRD)

and thermal gravimetric analysis-differential thermal analysis (TG-DTA).The influence of reaction time and temperature on the morphology of Mg(OH)2 nanoparticles was investigated by experiments

and based on the reaction process of bubbling gaseous ammonia into magnesium chloride solution

the morphology and growth mechanism of Mg(OH)2 nanoparticles were analyzed and discussed. It will be widely used in industry due to its simple process and special morphology.