Fig. 4From: Study of energy transfer mechanism from ZnO nanocrystals to Eu3+ ionsThe emission centres of ZnO-nc in (a) ZnO-nc:SiO2 and (b) Eu3+ 0.12:(ZnO-nc:SiO2) samples annealed at 450 °C. See the main text for the various ZnO-nc emission centres. (c) The schematic energy level diagram of the emission centres of ZnO-nc in SiO2 Back to article page