Luminescent enhancement in ZrO2:Tb3+, Gd3+ nanoparticles by active-shell modification

Abstract

The enhanced luminescent properties of Tb³⁺ and Gd³⁺ doped ZrO₂ nanoparticles (NPs) modified by coating with a shell were investigated. The pure cores, synthesized by a hydrothermal process, are in a high quality tetragonal phase and a monoclinic phase with an average size constant of ~7 ± 2 nm. The thickness and composition of the SiO₂ shell can make a difference to the luminescent properties of the NPs. The intensity of the green light emission was enhanced remarkably after coating the active shell (containing Gd³⁺) around the ZrO₂:Gd³⁺, Tb³⁺ NPs. The increased photoluminescence (PL) intensity is attributed to a reduced non-radiative recombination based on a longer luminescence decay time and an energy transfer from the Gd³⁺ in the shell to the adjacent Tb³⁺ ions. These results are important for the future optoelectronic applications of the Tb-doped ZrO₂ nanoparticles.