Xu Jin, Tu Datao, Zheng Wei, Shang Xiaoying, Huang Ping, Cheng Yao, Wang Yuansheng, Chen Xueyuan
CAS Key Laboratory of Design and Assembly of Functional Nanostructures State Key Laboratory of Structural Chemistry, and Fujian Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 China.
Adv Sci (Weinh). 2018 Jul 25;5(10):1800766. doi: 10.1002/advs.201800766. eCollection 2018 Oct.
Homogeneous core-shell structured nanoparticles (NPs) are prevailingly designed to accommodate lanthanide emitters, and such an epitaxial shell deposited on core NP is generally believed to help eliminate surface traps or defects on the as-prepared core. However, upon electron-beam irradiation to core-shell-shell NaLuF:Gd/Yb/Er@NaLuF:Nd/Yb@NaLuF upconversion NPs (UCNPs), it is revealed that interfacial defects actually exist at the core-shell and shell-shell interfaces, even with a higher density than the bulk-phase defects in inner core. Because of such higher density of interfacial defects, the kinetic energies transferred from energetic electrons to atoms may trigger the faster Na/F atom ejections and outward atom migrations in the coating layers than in the inner core of NPs, which ultimately results in the in situ formation of novel yolk-shell UCNPs. These findings provide new insights into interfacial defects in homogeneous core-shell structured NaLnF NPs, and pave the way toward utilizing the interactions of high-energy particles with materials for in situ fabrication of novel nanostructures.
均匀核壳结构的纳米粒子（NPs）通常被设计用于容纳镧系发光体，并且通常认为沉积在核NP上的这种外延壳有助于消除所制备核上的表面陷阱或缺陷。然而，在对核壳壳结构的NaLuF:Gd/Yb/Er@NaLuF:Nd/Yb@NaLuF上转换纳米粒子（UCNPs）进行电子束辐照时，发现即使在核壳和壳壳界面处的界面缺陷密度高于内核中的体相缺陷密度，界面缺陷实际上仍然存在。由于这种较高密度的界面缺陷，从高能电子转移到原子的动能可能会引发涂层中比纳米粒子内核更快的Na/F原子喷射和向外原子迁移，这最终导致了新型蛋黄壳UCNPs的原位形成。这些发现为均匀核壳结构的NaLnF NPs中的界面缺陷提供了新的见解，并为利用高能粒子与材料的相互作用原位制备新型纳米结构铺平了道路。
