模板诱导/均相沉淀法制备板片状碱式碳酸镁及其生长机理的研究

摘要

In order to expand the application of the basic magnesium carbonate in the field of flame retardant,the plate-like basic magnesium carbonate (Mgs(CO3)4(OH)24H2O) was prepared successfully by template-mediated/homogeneous precipitation method,using magnesium chloride hexahydrate (MgCl26H2O) and urea (CO(NH2)2)as reaction materials.Phase and morphology of the product were characterized by X-ray diffraction (XRD),scanning electron microscope (SEM) and atomic force microscope (AFM),respectively.The results showed that well-crystallized plate-like Mgs(CO3)4(OH)24H2O can be prepared at the water bath temperature of 100 ℃C,water bath time of 24 h,the aging time of 5 h after adding organic template agent.The investigation on organic template mediated mechanism shows that the template affects the crystal morphology by changing surface energy of different crystal plane.Through a preliminary study on the growth mechanism of the product,it is found that the generation of the plate-like Mg5(CO3)4(OH)24H2O could be explained by two-dimensional nucleation/step growth mechanism.%为了扩大碱式碳酸镁在阻燃领域的应用,通过模板诱导/均相沉淀法,以六水氯化镁和尿素作为原料,成功合成了碱式碳酸镁晶体.分别采用XRD、SEM、AFM对所得样品进行物相和形貌表征.结果显示,添加有机模板剂,在水浴温度1000C条件下,反应24 h,陈化5h后可得到结晶良好的板片状碱式碳酸镁.对有机模板诱导机理的研究显示,模板剂通过改变不同晶面的表面能影响晶体形貌.初步探究了板片状碱式碳酸镁的生长,提出了“二维成核/台阶生长”机理.