Fluorescent Enhancement of CaF 2 : Nd 3+ Nanoparticles through a Concentration‐Gradient Core/Shell Hybrid Structure

In this contribution, we provided an efficient core/shell structure for CaF 2  : Nd 3+ based core/shell NPs, which has several traits below: hybrid core; homogeneous or heterogeneous core‐host and shell‐host; concentration‐gradient distribution of both doping ions and activator from inner to outer shell layer. Finally, A successive layer‐by‐layer doping method was utilized to synthesize various core‐based and concentration‐gradient hybrid Ce 3+ , Li + and activator (Nd 3+ ) shell layer core/shell(C/S) NPs, which could enhance the fluorescence of the CaF 2  : 6Nd(mol %) C/S NPs up to 21.4 times than that of core‐only NPs by doping much denser hybrid Ce 3+ and activator Nd 3+ in per unit volume and overcoming surface quenching.