A Study On Nanocrystalline MgO Powders Prepared By A Gel-Combustion Synthesis Technology

Nanocrystalline MgO is an important inorganic material, and has potential applications in chemistry, light industry, food, medication, paint, rubber, electron industry and so on. There are abundant and good magnesium mineral resources in our China, and MgO is also one of the important products of west saline of China. Therefore, in order to make full use of our magnesium resources, to advance MgO quality and to extend its application range, it is of great meaning to study the fabrication technology of nanocrystalline MgO powders.In this paper, nanocrystalline MgO powders were prepared by a gel-combustion synthesis technology. The results show that, the link of citric acid with Mg2+ is strong and it is easy to prepare gel by citric acid, whereas the link of urea with Mg2+ is weak and it is difficult to prepare gel. So, citric acid is in favor of preparing fine nanocrystalline MgO. In addition, the radio of Mg(NO3)2 to citric acid has remarkable effects on the process of combustion synthesis, when the radio is 2/1, the dry gel can completely burn. Moreover, the combustion speed is fast, and the synthesized powders are pure MgO with a fine grain size. The effects of both the pH value of precursors and the temperature of the bathtub on the gel formation, morphology, combustion behavior and the crystalline size of the synthesized powders are systematically investigated. When the pH value is 7 and the temperature of the bathtub is 80℃, the time of the formation of gel is the shortest and the prepared dry gel has lots of small openings which was in favor of burning.Besides, the effects of ignition temperature and calcining temperature on the synthesized powders were also investigated in this paper. The results show that both of the two parameters have some effects on the size, shape and conglomeration of the synthesized powders. When igniting temperature is 500℃and calcining process is 600℃for 1 hour, nanocrystalline MgO powders with none organic compound left and low conglomeration can be obtained.In condition of the optimized parameters, pure nanocrystalline MgO powders with a average diameter of 10nm and BET value of 34.8234m2·g-1 were obtained; the nanocrystalline MgO powders produced put up infrared characteristic different with nubbly MgO, the A apex of which put up obvious Einstein shift. Therefore, it is proved that nanocrystalline MgO powders can be prepared by this simple gel-combustion synthesis method.