Effect of Yb³⁺ Concentrations on the Upconversion Luminescence Properties of ZrO₂:Er³⁺,Yb³⁺ Phosphors

Abstract

ZrO2:Er3+ and ZrO2:Er3+,Yb3+ phosphors were synthesized via a solvothermal reaction method. For low concentrations of Yb3+, the crystalline structure changed from the tetragonal to monoclinic phase as sintering temperature increased. As the Yb3+ concentration increased to a value above 0.05 mol, ZrO2 phosphors displayed a very stable tetragonal phase. The green and red upconversion emissions of ZrO2:Er3+,Yb3+ phosphors were measured under the excitation with a 975 nm continuous wave diode laser, and the pump power dependence of upconversion intensity was investigated. As the Yb3+ concentration increased from 0 to 0.05 mol, the red upconversion emission intensity increased more rapidly than the green emission intensity. This is attributed to the energy transfer (4I11/2→4I15/2 4I13/2→4F9/2) between Er3+ ions and the energy back transfer [4S3/2 4I13/2(Er3+)→2F7/2 2F5/2(Yb3+)] between the Er3+ and Yb3+ ions. In this case, the pump power dependence of red emission intensity changed from quadratic to linear as Yb3+ concentration increased.

Understanding Energy Transfer Mechanisms for Tunable Emission of Yb3+-Er3+ Codoped GdF3 Nanoparticles: Concentration-Dependent Luminescence by Near-Infrared and Violet Excitation

“…The ET3 process was proposed by Salas et al, where the enhanced red emission was mainly ascribed to CR 4 S 3/2 (Er) + 4 I 15/2 (Er) → 4 I 9/2 (Er) + 4 I 1132 (Er) and subsequent ETU I 13/2 (Er) + 2 F 5/2 (Yb) → 4 F 9/2 (Er) + 2 F 7/2 (Yb). Recently, an ET mechanism, where an efficient EBT process 4 F 7/2 (Er) + 2 F 7/2 (Yb) → 4 I 13/2 (Er) + 2 F 5/2 (Yb) and subsequent ETU process 4 I 13/2 (Er) + 2 F 5/2 (Yb) → 4 F 9/2 (Er) + 2 F 7/2 (Yb) are ascribed to the green and red spectral tailoring, is proposed by Zhang et al , and developed by Cao’s team and Jeong’s team . The EBT process is becoming more prominent due to the reduced average distance between Yb 3+ and Er 3+ ions, which is also illustrated in Figure .…”

Lanthanide-Doped KLu2F7 Nanoparticles with High Upconversion Luminescence Performance: A Comparative Study by Judd-Ofelt Analysis and Energy Transfer Mechanistic Investigation

“…Early studies contributed the population of 4 F 9/2 manifold to the multiphonon3334 and cross-relaxation processes3536. Recently, an EBT process involving Er 3+ 2 H 11/2 / 4 S 3/2 and 4 I 13/2 manifolds was proposed and proved to account for the greatly enhanced red emission262837. A new UC mechanism involving the population of 4 F 9/2 manifold through an EBT process from high-lying level 4 G 11/2 was proposed3839.…”

The green upconversion emission mechanism investigation of GdVO4:Yb3+, Er3+ via tuning of the sensitizer concentration

“…However, the ESA processes of Er3þ ions are neglected. Because the Yb 3þ ion has a much larger absorption cross section and an efficient energy transfer to Er3þ ions under laser excitation of 975 nm [26]. Therefore, the energy transfer upconversion (ETU) process has occurred better than the ESA process.…”