Surface and defect modifications in mixture of ZnO and carbon nanocrystals at mechanical processing

The Raman scattering and photoluminescence (PL) spectra, PL temperature dependences and scanning electronic microscopy (SEM) images have been studied in the mixture of ZnO+1.0%C nanocrystals (NCs) before and after intensive mechanical processing (MP). The study reflects the diversity of physical processes occurring at MP: the amorphization of the ZnO NC surface, transforming an amorphous graphite into graphene monolayers covered of ZnO NCs, changing the ZnO NC shape owing to the plastic deformation and crushing the individual ZnO NCs, the partial oxidation of graphene layers with the formation of graphene oxide passivating ZnO NCs, the formation of graphite oxide when temperature increasing at MP, as well as the ZnO defect modification near the surface of ZnO NCs, etc. Additionally the new 'blue” PL band peaked at 2.82-2.92 eV has been revealed in PL spectra after MP, which is assigned to emission of graphite (graphene) oxides. All mentioned processed have been studied and discussed in details.