均相成核—水热法制备纳米氧化锌

制备纳米氧化锌的关键是成核与生长控制。采用尿素为均相沉淀剂 ,结合水热处理 ,温度 130℃ ,反应时间为 3～ 5h制备了粒径小 ,分布窄的纳米氧化锌。Zn2 +的均相成核与其浓度、OH- 的浓度有关 ,体系中Zn(OH) 2 的过饱和度越大 ,则成核数量越多 ,所制备的氧化锌颗粒越小 ;与以氢氧化锌胶体为前驱体的共沉淀技术相比 ,均相沉淀技术有利于氧化锌纳米晶粒均匀生长 ;此外 ,添加有机物作分散剂可以减弱微小晶粒间的叠合生长 ,有利于制备均一性较好的纳米氧化锌。

Synthesis of Nanoscale ZnO by Homogeneous Nucleation in Hydrothermal Process

Using urea as homogeneous precipitation agent,nanosize zinc oxide crystalline with a small size and a narrow size ditribution has been synthesized at 130℃ and a reaction time 2～5h by homogeneous nucleation method in hydrothermal process.The greater the supersuturaton of Zn(OH) 2,the more the nuclei,and the smaller the crystallines.The number of nuclei formed in the nucleation process depends on the concentration of Zn 2+ and OH -.Compared with the dissolution and recrystallization process in which Zn(OH) 2 colloid as precursors,homogeneous nucleation techniques is advantageous to the formation of uniform ZnO nanocrystallines.In addition,organic compoud as dispersant can prevent the growth of crystallite by congruence which results a large crystal size and wide size distribution.