片状氢氧化镁热解制备微纳结构氧化镁

Preparation of micro-nanostructured magnesium oxide by pyrolysis of magnesium hydroxide

采用沉淀法以六水氯化镁(MgCl2·6H2O)和氨水(NH3·H2O)为原料制备出氢氧化镁,热解得到了片状镂空纳米氧化镁。利用Kissinger法计算出氢氧化镁的热解表观活化能E和指前因子A,并用Ozawa-Flynm-Wall方程法进行了验证;采用Satava法分析得出氢氧化镁热解机理为随机成核及生长;通过TEM和SAED分析,该氧化镁纳米级平均粒径在20 nm左右,微米级尺寸在200~500 nm之间,暴露晶面族为{110};经XRD分析,氧化镁微纳结构的形成机理与前驱体热解过程中分解产物逸出方式以及晶体结构变化有关。

In this paper,magnesium hydroxide was prepared by precipitation method with magnesium chloride hexahydrate and ammonia water as raw materials.Subsequently,the sheet-like hollow nano-MgO was obtained by pyrolysis of the resulting magnesium hydroxide.The pyrolysis apparent activation energy E and the pre-exponential factor A of magnesium hydroxide were calculated by the mean of Kissinger method,and verified by Ozawa-Flynm-Wall equation method.The pyrolysis mechanism was studied by Satava method,which indicated the thermal decomposition of Mg(OH)2 was as random nucleation and growth.The results showed the nanometer diameter of MgO was about 20 nm and the micron size was between 200 and 500 nm by Transmission electron microscopy(TEM)images.The corresponding selected-area electron diffraction(SAED)pattern demonstrated the single-crystalline nature with the exposed plane of{110}.Meanwhile,it found the formation mechanism of magnesium oxide with micro-nano structure was related to the changes of crystal structure and the way of the decomposition products escaping during pyrolysis.