Comparative Investigation of Green and Red Upconversion Luminescence in Er³⁺ Doped and Yb³⁺/Er³⁺ Codoped LaOCl

Abstract

Pure tetragonal LaOCl:Er 3+ and LaOCl:Yb 3+ /Er 3+ samples possessing upconversion (UC) luminescence behavior were synthesized using a simple solid-state reaction method and the structural properties were investigated using X-ray diffraction, crystal structure analysis, and SEM, respectively. The UC spectroscopic properties of Er 3+ doped and Yb 3+ /Er 3+ codoped LaOCl were studied in terms of UC emission spectra. The intense green and red emissions around 528, 550, and 662 nm corresponding to the 2 H 11/2 ?4I 15/2 , 4 S 3/2 ? 4 I 15/2 , and 4 F 9/2 ? 4 I 15/2 transitions of Er 3+ ions were observed for LaOCl:Er 3+ sample under excitation at 980 nm, and the power studies indicated that two-photon processes were responsible for the green and red upconversion luminescence. The bright green emission is visible to the naked eyes for LaOCl: Er 3+ . A great enhancement of the visible upconversion emissions in Yb 3+ /Er 3+ -codoped sample was observed, furthermore, it is interesting to find the bright red emission for LaOCl:Yb 3+ /Er 3+ samples. The mechanisms for the green and red UC luminescence, especially the enhancement of red UC emission were discussed based on the law of UC intensity versus pump power and their lifetimes.

A Novel Scheme to Obtain Y2O2S:Er3+ Upconversion Luminescent Hollow Nanofibers via Precursor Templating

“…From the above result, it has been proved that the green and red emissions The upconversion excitation processes can be composed by several well-known mechanisms: (1) ground state absorption (GSA); (2) excited state absorption (ESA), (3) energy transfer (ET), and (4) photon avalanche (PA). 39,40 We can immediately rule out PA as a mechanism of upconversion in Y 2 O 2 S:Er 3+ hollow nanofibers because no inflection point is observed in the power density study. The two-photon process in Y 2 O 2 S:Er 3+ hollow nanofibers may happen via the following GSA and ESA processes (Fig.…”

Preparation, crystal structure and up-conversion luminescence of Er3+, Yb3+ co-doped Gd2(WO4)3

“…In the spectra, two strong green emission bands centered at 532nm and 553nm and a weak red emission band centered at around 669nm are observed, which are assigned to the Er 3+ ion transitions of 4 20,35,37 The UC luminescence spectra of single Er 3+ doped and 0.03 Er 3+ /yYb 3+ (y=0-0.25) co-doped Gd 2 (WO 4 ) 3 under 980nm nearinfrared laser excitation are presented in Figure 6, and the inset shows the variation of the UC luminescent intensity at 532nm and 553nm on the Yb 3+ concentration increase. Similarly, when singly doped with Er 3+ ion, the UC spectrum includes very weak UC emission, because Er 3+ solely can hardly absorb the near-infrared excitation energy in the absence of sensitizer Yb 3+ ions.…”

“…[16][17][18][19] Of , and it can be easily substituted by Er 3+ and Yb 3+ . 20,21 Li et al 22 prepared Er 3+ /Yb 3+ codoped Gd 2 (WO 4 ) 3 via a co-precipitation method, and investigated pumping-route-dependent concentration quenching and temperature effect on the phosphors. Sun et al 23 prepared the Yb 3+ and Er 3+ co-doped Gd 2 (WO 4 ) 3 and Gd 2 WO 6 using coprecipitation method, and reported the up-converted emission differences between those two phosphors.…”

A feasible strategy to synthesize LaOI:Yb3+/Ho3+ upconversion luminescence nanostructures via succeeding to the morphologies of precursors

“…The structure of LaOI comprises distinct covalent (LaO) n n+ complex cation and I -anion layers. In this structure, the La 3+ ion is coordinated with four oxygens and five iodines forming a monocapped tetragonal antiprism arrangement with C 4v as the point symmetry of the La 3+ site [34]. Meanwhile, La 3+ ion has the largest ionic radius among the lanthanide ions, and it can be easily substituted by different Ln 3+ ions in the structure [35].…”