Fabrication of Multifarious Nanoparticles Inside a TEM: An In Situ Evaporation and Deposition Method

Revealing the surface effect of nanoparticles (NPs) is one of the key prerequisites for understanding their extraordinary properties at the nanometer scale. However, active NPs frequently suffer from surface oxidation and contamination, which hinders the realization of their delicate surface-related properties. Upon this issue, this paper develops an in situ evaporation and deposition (in-E&D) method inside a transmission electron microscope (TEM), by which NPs with ultra-clean surfaces can be controllably fabricated and examined. More than 12 types of materials, including Mg, Al, Cr, Mn, Ni, Cu, Zn, Ge, Ag, Sb, Pb, Bi, etc., have been demonstratively verified, and diverse NPs/nanorods have been obtained with featured structures, shapes, phases, etc. It is found that the electron beam-induced thermal effect and the vapor pressure of the precursor material are two decisive parameters for this in-E&D method. With appropriate settings, NP size, number density, and distribution can be designedly modulated. With alloyed/mixed precursors, the in-E&D method can be extended to fabricate binary and even more complex NPs in demand. It provides an effective chance to uncover the property and behavior of delicate NPs which are sensitive and prone to contamination during sample transfer.