In situ epitaxial growth of GdF3 on NaGdF4:Yb,Er nanoparticles

Abstract

NaGdF₄ is a well-known up-conversion material with potential applications in lasers and biolabels and used to be known as a thermally stable material bearing harsh natural conditions. In this work, a TEM electron beam was found to be able to manipulate the morphology of cubic-NaGdF₄, changing it from solid nanoparticles to porous materials with nano-sized vacancies by electron beam irradiation. Electron beams also induce a structure change from cubic-NaGdF₄ to GdF₃. By controlling the current density of the TEM electron beam, the in situ epitaxial growth behavior of GdF₃ (020) was observed at the NaGdF₄ (111) interface. Structural correlations between two compounds were discussed to understand the epitaxial growth with a large lattice mismatch. These findings suggest a TEM electron beam can be used not only as an imaging tool, but also as an alternative paradigm for manipulating matter.