Synthesis Of One Dimensional Nanosacle Magnesium Serial Materials

A solution based synthesis route is developed in this paper, which is capable of preparing basic magnesium chloride rods, magnesium hydroxide nanorods and magnesium oxide nanorods with single crystal structure. It involves 1D growth of basic magnesium chlorides rods in solutions and subsequent transformation from this precursor to intermediate magnesium hydroxide nanorods. Finally magnesium hydroxide nanorods are calcined to produce magnesium oxide nanorods. Preparation factors are systematically investigated, including starting materials, temperature, dispersant, solvent, drying methods and calcination conditions, etc. and products are characterized by XRD, SEM, TEM, TG and SAED in order to determine a better synthesis conditions for each step. Discussions on the kinetic mechanism of magnesium hydroxide nanorods are also made.Basic magnesium chlorides rods with diameters of 100-200nm and lengths ranging 4-8 μ m are prepared under the following synthesis conditions: agitating rate:900r/min; synthesis temperature: 40℃⁶0℃; ageing time: above 14h; concentration of magnesium chloride: 4mol/L⁴.5mol/L; mole ratio of MgO/MgCl₂: 0.1 ⁰.15:1;drying temperature: below 85℃.Magnesium hydroxide nanorods with diameters range from 100nm to 150nm with an average 3-5 μ m of lengths are synthesis when basic magnesium chlorides rods are used as precursor and 1mol/L sodium hydroxide as precipitator. The determined synthesis conditions are as following: reaction solvent (ethanol/water): 3:1; dispersant: PEG-6000 and PEG —400; drying process: solvent exchange supercritical CO₂ drying and solvent exchange microwave drying.Magnesium oxide nanorods with diameters of 40-150nm and lengths of 1 μ m or above are successfully synthesized by calcining magnesium hydroxide nanorods under the temperature of 450℃ for 180min while at a low heating rate of 5℃/min. The periclase magnesium oxide presents a transformation to cubic magnesium oxide at the temperature of 550℃-650℃。Differential and integral mechanism functions for the decomposition of magnesium hydroxide nanorods are obtained by analyzing the thermal decomposition of magnesium hydroxide nanorods using thermalgravimeteric data:f(α) = 1-α and F(α) = And under non-isothermal conditions, the decomposition kinetic equation for magnesiumhydroxide nanorods is deduced to be:da/dT = Base on the above analysis, the decomposition activation energy of magnesium hydroxide is also evaluated to be 197kJ/mol.