LaF₃, CeF₃, CeF₃:Tb³⁺, and CeF₃:Tb³⁺@LaF₃ (Core−Shell) Nanoplates:  Hydrothermal Synthesis and Luminescence Properties

LaF 3, CeF 3, CeF 3:Tb 3+, and CeF 3:Tb 3+ @LaF 3 (core−shell) 2D nanoplates have been successfully synthesized by a facile and effective hydrothermal process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra as well as kinetic decays were used to characterize the samples. The experimental results indicate that the organic additive, trisodium citrate (Cit 3- ), as a shape modifier has the dynamic effect by adjusting the growth rate of different crystal facets, resulting in forming the anisotropic geometries of the final products. The possible formation mechanisms for different products have been presented. The CeF 3, CeF 3:Tb 3+, and CeF 3:Tb 3+ @LaF 3 (core/shell) nanoplates show characteristic emission of Ce 3+ (5d−4f) and Tb 3+ (f−f), respectively. By coating the LaF 3 shell on the surface of the CeF 3:Tb 3+ core, the distance between the luminescent lanthanide ions is increased and the surface quenchers are decreased, thus reducing the nonradiative pathways. The luminescent intensity and lifetime of the CeF 3:Tb 3+ @LaF 3 core/shell nanoplates are enhanced with respect to the bare CeF 3:Tb 3+ nanoplates.