摘要
本文使用气体样品杆在透射电子显微镜中原位观察了PtNi纳米颗粒在一个大气压的氧气环境下300℃退火过程中的动态变化。实验发现,与真空退火相比,PtNi纳米颗粒在氧气环境中退火稳定性变差,颗粒之间发生剧烈融合。Ni元素由于具有很高的氧亲和能,在退火过程中氧气会诱导Ni从PtNi纳米颗粒的内部向外迁移,并氧化形成NiO团簇。对反应后样品的成分分布应用球差校正STEM-HAADF及EDS进行分析,结果表明融合区域Pt元素富集。推测颗粒快速融合可能的原因是形成了易挥发的PtOx物质,加速了颗粒间的传质过程。
An in-situ study of structure evolution of PtNi nanoparticles annealed at 300 ℃ under atmospheric pressure oxygen was carried out by TEM with a gas cell holder. In contrast to the high stability of the sample annealed in vacuum, significant coalescence was observed when the sample was annealed in the presence of oxygen. During the annealing in oxygen, nickel migrated outward from the nanoparticles and was oxidized to NiO cluster.Such migration and phase segregation can be attributed to the high oxygen affinity of Ni.Composition distribution of the nanoparticles after treatment in oxygen was investigated by high angle annular dark-field STEM and EDX mapping. Pt was found to be enriched in the coalescence region, indicating that the coalescence was probably induced by the formation of volatile PtOx that enhanced mass transfer process between particles.
作者
盛丽萍
王勇
张泽
SHENG Li-ping;WANG Yong;ZHANG Ze(Center of Electron Microscopy,State Key LaboratolT of Silicon Materials,and Department of Materials Science and Engineering,Hangzhou Zhejiang 310027,China)
出处
《电子显微学报》
CAS
CSCD
北大核心
2018年第5期391-396,共6页
Journal of Chinese Electron Microscopy Society
基金
国家自然科学基金资助项目(Nos.51390474
91645103
11327901)
