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

Aleksandra A Vidyakina,Erkki Lähderanta,Andrey S Mereshchenko,Mikhail Y Skripkin,Nikita A Bogachev,Ilya I Tumkin,Ilya E Kolesnikov

doi:10.3390/ma13153397

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.

Highlights

IntroductionRare earth-based materials are known to demonstrate efficient upconversion properties and are able to transform near-infrared (NIR) light to visible or even UV light via multiphoton processes [1,2,3]
Rare earth-based materials are known to demonstrate efficient upconversion properties and are able to transform near-infrared (NIR) light to visible or even UV light via multiphoton processes [1,2,3].NaYF4 doped by rare earth ions is one of the most efficient upconversion phosphors among numerous luminescent materials due to the low phonon energy of host lattice, which reduces the amount of nonradiative transitions [4,5]
Introduction of Gd3+ ions in the NaYF4 host leads to the formation of crystal lattice defects, as shown in Figure 2c,d, which change the symmetry of the surroundings of ytterbium, emission intensity (IUC) increased proportionally to the pumping power (p) of the excitation source according to IUC–Pn, where n is the number of photons that pump the population in a particular energy level [26,36]

Summary

Introduction

Rare earth-based materials are known to demonstrate efficient upconversion properties and are able to transform near-infrared (NIR) light to visible or even UV light via multiphoton processes [1,2,3]. NaYF4 doped by rare earth ions is one of the most efficient upconversion phosphors among numerous luminescent materials due to the low phonon energy of host lattice, which reduces the amount of nonradiative transitions [4,5]. NaYF4 : Yb3+ , Tm3+ /Er3+ upconversion microcrystals are known to have the best luminescence property of all fluorescent materials [15]. Different methods for the synthesis of NaYF4 : Yb3+ , Tm3+ /Er3+. Microcrystals of a larger size (>500 nm), which can be fabricated by hydrothermal synthesis, usually have higher luminescence intensity. The Tm3+ and Er3+ ions act as optical active centers; the Yb3+ ion is a sensitizer that absorbs NIR light and transfers energy to Tm3+ or Er3+

Methods

Results

Conclusion