一步法合成纳米氧化锌的结晶动力学分析

从相变驱动力、成核功、成核速率和晶体生长速率等四个方面探讨了一步法合成纳米氧化锌的结晶动力学问题。理论分析与试验结果相比较表明,影响纳米氧化锌晶粒形成与生长的因素主要是反应温度、反应物起始浓度和过饱和比。纳米氧化锌合成过程中,既有均匀成核,又有非均匀成核。加快成核速率的途径有升高成核时的温度、增大成核时反应物浓度和增大过饱和比。而晶体的生长也受合成条件的影响,温度升高及过饱和比增大均会遏制晶体的生长,从而获得粒度细小且分布窄的纳米氧化锌粉体。

DISCUSSION ON CRYSTALIZATION KINETICS OF NANO-ZnO SYNTHESIZED BY ONE-STEP METHOD

In this paper,the problem of crystallization kinetics for nano-ZnO synthesized by one-step method in the views of phase transition force,nucleation,nucleation rate and crystal growth rate was discussed. Theoretical analysis and experimental results indicate that the influencing factors of crystal formation are mainly reaction temperature and original reaction concentration ratio.Both uniform nucleation and non-uniform nucleation are developed during the course of synthesizing of nano-ZnO.Approaches to expediting nucleation rate are temperature original reaction concentration and supersaturation ratio in the nucleation course.Whereas synthesizing conditions produce an effect on the crystal growth,meaning that raising temperature or increasing supersaturation ratio may inhibit the crystal growth,resulting in nano-ZnO powder with fine particle size plus narrow size distribution obtained accordingly.