Restructuring and Remodeling of NaREF 4 Nanocrystals by Electron Irradiation

NaREF 4 nanocrystals are found to be highly manipulable by electron beam irradiation. With 200 kV electron beam irradiation, both 14.6 nm spherical NaGdF 4 :Yb,Er nanoparticles and 44.7 nm × 34.1 nm ellipsoidal NaYF 4 :Yb,Er nanorods form hollow structures and eventually convert to the corresponding REF 3 upon prolonged irradiation. Furthermore, the NaYF 4 nanorods fractured with irradiation with a 100 kV electron source are found to be subsequently self‐healed when irradiated with a 200 kV source. The detailed experimental results, in combination with theoretical analysis, suggest that knock‐on effects, specific lattice energy, and the inherently low surface energy of NaREF 4 collectively contribute to the formation of the hollow structures. These mechanisms allow controlled engineering and manipulation of RE nanomaterials on the nanometer scale.