Up/down conversion luminescence and energy transfer of Er3+/Tb3+ activated NaGd(WO4)2 green emitting phosphors

Lingling Jiang; Guixia Liu; Dan Li; Xiangting Dong; Wensheng Yu

doi:10.1016/j.saa.2018.04.041

Up/down conversion luminescence and energy transfer of Er³⁺/Tb³⁺ activated NaGd(WO₄)₂ green emitting phosphors

Spectrochim Acta A Mol Biomol Spectrosc. 2018 Aug 5:201:88-97. doi: 10.1016/j.saa.2018.04.041. Epub 2018 Apr 22.

Authors

Lingling Jiang¹, Guixia Liu², Dan Li¹, Xiangting Dong¹, Wensheng Yu¹

Affiliations

¹ Key laboratory of Applied Chemistry and Nanotechnology at University of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China.
² Key laboratory of Applied Chemistry and Nanotechnology at University of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China. Electronic address: liuguixia22@163.com.

PMID: 29734109
DOI: 10.1016/j.saa.2018.04.041

Abstract

A series of double scheelite-type tungstate green phosphors NaGd(WO₄)₂:Er³⁺, Tb³⁺ were synthesized by a hydrothermal route and subsequent calcination process, and they were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometry (EDS), photoluminescence spectroscopy and fluorescence lifetime measurements. The phosphors take on octahedral microcrystals with a mean side length of ~2 μm. In the single doped phosphors system, the energy transfer processes from WO₄^2- to Er³⁺ or Tb³⁺ were discussed. The quenching concentrations of Er³⁺ and Tb³⁺ are 0.05 and 0.07, respectively. The critical distances for Er³⁺ and Tb³⁺ ions are calculated to be 14.28 Å and 12.76 Å, respectively. When doping Er³⁺/Tb³⁺ is applied in the single compound, the concentration quenching effect of Tb³⁺ ions occurs via a resonant-type dipole-dipole interaction as well as that of Er³⁺ ions. Under the excitation with ultraviolet (378 nm) or infrared (980 nm) light, the Er³⁺/Tb³⁺ co-doped NaGd(WO₄)₂ phosphors emit strong green emission. The obtained samples with bright emission intensity and appropriate decay time are suitable for use as green phosphors in the near ultraviolet LEDs and bioimaging applications.

Keywords: Energy transfer; Green phosphors; Hydrothermal method; Photoluminescence.