非晶对置换反应中Ag纳米晶生长的影响

Influences of Amorphous Phase on the Growth of Nanocrystalline Ag during Replacement Reactions

摘要:

研究在Zn、Cu置换AgNO3溶液反应中非晶膜的形成对纳米Ag晶体生长的影响。HRTEM的观察表明，置换反应中形成的纳米Ag晶体的生长前沿沉积有一层5~10 nm宽的非晶膜，纳米Ag晶体的长大取决于该非晶膜的自发晶化。非晶膜的自发晶化主要是在非晶层内原位成核、长大，也可在晶体和非晶的界面成核长大，还可观察到非晶层内的Ag原子直接排列到原晶体的界面上而不需要成核的过程。在纳米Ag晶体生长前沿沉积的非晶的稳定性取决于AgNO3溶液的浓度。在80 mmol·L-1 或更低的AgNO3溶液中生成的Ag纳米晶的生长前沿沉积有较稳定的非晶膜，而在400 mmol·L-1 的高浓度AgNO3溶液中Zn置换还原形成的纳米Ag晶体的生长前沿无非晶存在

Abstract:

Influences of amorphous film formation on the growth of nanocrystalline Ag during replacement reactions were investigated. Amorphous films with a thickness of 5-10 nm were observed by HRTEM on the growth tip of Ag nanopaticles. The growth of Ag nanocrytallines depends on the in situ crystallization of amorphous films. Both in situ nucleation of crystalline Ag in amorphous films and without nucleation can take place. The stability of amorphous films depends on the concentration of AgNO3 solution. In 80 mmol·L-1 or lower AgNO3 solution, amorphous films can exist stably, while in 400 mmol·L-1 AgNO3 solution no amorphous films can be detected