BaF2纳米粉体的沉淀制备和成核机制

Syntheses and nucleation for nanocrystalline powders of barium fluoride by precipitation in aqueous solutions

采用NH4F和Ba（NO3）2水溶液沉淀反应制备BaF2纳米粉体，在临界过饱和和快速混合过饱和反应条件下分别获得了10nm和80nm的BaF2沉淀粉体，对不同沉淀反应条件下的成核机制进行了分析。对于低浓度Ba（NO3）2溶液和NH4F固体快速混合反应情形，讨论了过饱和度的合理计算和扩散对形核的作用。

The nanocrystalline （nano-） powders of BaF2 were synthesized by precipitation reactions of NH4F solids with BaNO3）2 aqueous solutions. The nano-powders with the average grain size of 10 nm and 80 nm were obtained under the conditions of the critical supersaturation and of the supersaturation by fast mixing, respectively. The nucleation mechanisms of nano-precipitates were analyzed. The reasonable evaluation of the super saturation and the action of diffusion on the nucleation of the nano-precipitates was discussed for the case of the rapid reaction of the low mass concentration Ba（NO3）2 aqueous solutions with the excess solid NH4F.