Gd3+-Doping Effect on Upconversion Emission of NaYF4: Yb3+, Er3+/Tm3+ Microparticles

Abstract

β-NaYF₄ microcrystals co-doped with Yb³⁺, Er³⁺/Tm³⁺, and Gd³⁺ ions were synthesized via a hydrothermal method using rare-earth chlorides as the precursors. The SEM and XRD data show that the doped β-NaYF₄ form uniform hexagonal prisms with an approximate size of 600-800 nm. The partial substitution of Y by Gd results in size reduction of microcrystals. Upconversion luminescence spectra of microcrystals upon 980 nm excitation contain characteristic intra-configurational ff bands of Er³⁺/Tm³⁺ ions. An addition of Gd³⁺ ions leads to a significant enhancement of upconversion luminescence intensity with maxima at 5 mol % of dopant.

Keywords: hydrothermal synthesis; luminescence; microcrystals; rare earth; upconversion.