聚乙二醇、EDTA和柠檬酸对氧化沉淀法制备纳米Mn3O4晶粒尺寸的影响

Effect of Polyethylene Glycol,EDTA and Citric Acid on the Grain Size of Nano-Mn3O4 Prepared by Oxidation Precipitation Method

采用氧化沉淀法在低温下反应制备纳米Mn3O4,反应中加入适量的有机添加剂聚乙二醇、EDTA和柠檬酸,以确定不同添加剂对Mn3O4晶粒尺寸的影响;采用XRD和TEM分别对产物的晶相和形貌进行了表征.结果表明,加入三种不同的添加剂均可得到较小粒径的Mn3O4,其中柠檬酸对晶粒尺寸的调控作用最有效.对Mn3O4粒径调控机理进行了推测:聚乙二醇作为表面活性剂,在一定程度上阻止了产物的晶化.EDTA和柠檬酸分子中含有羰基、羟基或羧基等多电子基团,在Mn3O4晶化过程中可与Mn 2+发生络合反应生成络合物,络合物扮演了模板剂的作用,不同程度地阻碍了Mn3O4晶体的生长,从而得到了较小粒径的Mn3O4.

Mn3O4 nanocrystals were produced by oxidation-precipitation method at a low temperature,adding appropriate amount of organic additives which include polyethylene glycol,EDTA and citric acid to explore the effect of organic additives on the grain size of Mn3O4.Crystal phase and morphology of samples were characterized by means of X-ray diffraction(XRD)and transmission electron microscopy(TEM)respectively.The results showed that organic additives could reduce the nano-size of Mn3O4,however,citric acid was the most effective in regulating the particle size.The regulation mechanism of Mn3O4 particle size was speculated.As a surfactant,polyethylene glycol prevents the Mn3O4 crystal growth in a certain extent.EDTA and citric acid molecules all contain multi-electron groups such as carbonyl,hydroxyl or carboxyl groups,during the crystallization of Mn3O4,they formed a complex with Mn 2+.The complex acted as a template which hindered the growth of Mn3O4 crystals and finally Mn3O4 with a smaller particle size was produced.