摘要
研究了合成条件(原料种类、加料次序、NaOH浓度和合成温度)对液相法制备镁铝水滑石试样的相组成的影响.以MgCl2为镁源、NaAlO2为铝源、NaCO3和NaOH为沉淀剂,在常压下采用液相法制备了长度约100nm、直径约10nm的Mg6Al2(OH)16CO3-4H2O针状纳米晶体.并且发现:可溶性原料的选取、最后加入MgCl2的加料次序、>45℃的合成温度和保证反应溶液的pH>12,是瞬间生成镁铝水滑石纳米晶的充分必要条件.提出镁铝水滑石纳米晶核形成的过程是:均匀分布于溶液中的Al13(OH)32 7+迅速吸附于带羟基OH-的无定型态的Mg(OH)2表面,并进行Al3+扩散,为平衡电价,CO32-也扩散进入Mg(OH)2,从而在瞬间完成镁铝水滑石晶核的形成.
The acicular nanocrystalline Mg, Al-hydrotalcite flame-retardant agent, its length being about 100 nm and its diameter being about 10 nm, was prepared by the liquid method at normal atmosphere. The effect of preparation technology, which includes the raw material choice, adding raw material sequence, NaOH concentration, and nucleation temperature, on its phase composition was discussed. And it is found that the sufficient condition of obtaining nanocrystalline Mg, Al-hydrotalcite is as follows: (1) raw materials must be solubility; (2) pH value of the reaction solution must be greater than 12; (3) the nucleation temperature must be higher than 45°C; and (4) the adding raw material sequence must be that adding raw material MgCl2 follows the other three raw materials. Moreover, it is put forward that the nucleation process of nanocrystalline Mg,Al-hydrotalcite is as follows: firstly, Al13(OH)327+ ions are attracted on the surface of amorphous Mg(OH)2 and Al3+ ions diffuse in the Mg(OH)2; secondly, CO32- is inserted in the framework for the balance of the electron valence; finally, the nucleation of nanocrystalline Mg, Al-hydrotalcite is quickly finished.
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2004年第5期977-984,共8页
Journal of Inorganic Materials
基金
教育部教育振兴行动计划资助项目
关键词
镁铝水滑石
制备工艺
合成机理
纳米晶体
Aluminum compounds
Magnesium compounds
Nanostructured materials
Nucleation
Phase composition
Raw materials
Synthesis (chemical)
Transmission electron microscopy
X ray diffraction analysis
