Figure 4

AFM images of the CeO2 sample without NH3 plasma treatment and with NH3 plasma treatment for 3 min. The normalized C-V curve of the Ce2Ti2O7 sample without and with NH3 plasma treatment for 3 min.
AFM images of the CeO2 sample without NH3 plasma treatment and with NH3 plasma treatment for 3 min. The normalized C-V curve of the Ce2Ti2O7 sample without and with NH3 plasma treatment for 3 min.