In situ structural evolution from GeO nanospheres to GeO/(Ge, GeO2) core-shell nanospheres and to Ge hollow nanospheres

In situ structural evolution by electron beam irradiation generated within a transmission electron microscopy from amorphous GeO nanospheres, which were synthesized by thermal oxidation from Ge powders, to GeO/(Ge, GeO2) core-shell nanostructures, and to final Ge polycrystalline hollow nanospheres was examined and studied. In this structural evolution process, the formation of GeO/(Ge, GeO2) core-shell nanostructures was attributed to the gradual decomposition of GeO into Ge and GeO2, producing a Ge and GeO2 composite. Ge polycrystalline hollow nanospheres were formed by GeO2 evaporating and volatilizing out of the Ge and GeO2 composites' nanospheres under electron beam irradiation. This study demonstrated that electron beam irradiation within the transmission electron microscopy can be employed as an effective and promising tool to fabricate nanomaterials and nanostructures, especially for those that can not be fabricated using conventional chemical and physical methods.