Synthesis of magnesium oxychloride nanorods with controllable morphology and their transformation to magnesium hydroxide nanorods via treatment with sodium hydroxide

In this paper, the formation of magnesium oxychloride (Mg-x(OH)(y)Cl-z center dot nH(2)O) nanorods from the system MgO-MgCl2-H2O is investigated thoroughly. By systematically changing the adding amounts of the three starting materials, short nanorods (< 1 A mu) or long nanorods (up to 20 A mu) were obtained readily with the aspect ratio in the range of 10-70. The mechanism of the crystal growth and the change of the crystal phase from 5Mg(OH)(2)center dot MgCl2 center dot 8H(2)O (phase 5) to 3Mg(OH)(2)center dot MgCl2 center dot 8H(2)O (phase 3) is also discussed. The products were characterized by transmission electron microscopy X-ray diffraction, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The resulting magnesium oxychloride nanorods were further transformed to magnesium hydroxide (Mg(OH)(2)) nanorods with the shape remained by treating with NaOH at room temperature. The results shown in this paper indicate a facile pathway to produce magnesium oxychloride or magnesium hydroxide nanorods with controllable morphology on large scale.