Impacts of 5d electron binding energy and electron-phonon coupling on luminescence of Ce3+ in Li6Y(BO3)3

Yiyi Ou; Weijie Zhou; Dejian Hou; Mikhail G Brik; Pieter Dorenbos; Yan Huang; Hongbin Liang

doi:10.1039/c9ra00381a

Impacts of 5d electron binding energy and electron-phonon coupling on luminescence of Ce³⁺ in Li₆Y(BO₃)₃

RSC Adv. 2019 Mar 11;9(14):7908-7915. doi: 10.1039/c9ra00381a. eCollection 2019 Mar 6.

Authors

Yiyi Ou¹, Weijie Zhou¹, Dejian Hou², Mikhail G Brik^{3

4

5}, Pieter Dorenbos⁶, Yan Huang⁷, Hongbin Liang¹

Affiliations

¹ MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University Guangzhou 510275 China cesbin@mail.sysu.edu.cn.
² School of Materials Science and Engineering, Hanshan Normal University Chaozhou 521041 China.
³ College of Sciences, Chongqing University of Posts and Telecommunications Chongqing 400065 China.
⁴ Institute of Physics, University of Tartu Tartu 50411 Estonia.
⁵ Institute of Physics, Jan Długosz University PL-42200 Częstochowa Poland.
⁶ Faculty of Applied Sciences, Delft University of Technology Mekelweg 15 2629 JB Delft The Netherlands.
⁷ Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences Beijing 100039 China.

Abstract

In this work, the crystal structure and electronic structure as well as the synchrotron radiation vacuum ultraviolet-ultraviolet-visible (VUV-UV-vis) luminescence properties of Li₆Y(BO₃)₃ (LYBO):Ce³⁺ phosphors were investigated in detail. The Rietveld refinement and DFT calculation reveal the P2₁/c monoclinic crystal phase and the direct band gap of the LYBO compound, respectively. Only one kind of Ce³⁺ 4f-5d transition is resolved in terms of the low temperature VUV-UV excitation, UV-vis emission spectra and luminescence decay curves. Furthermore, by constructing the vacuum referred binding energy (VRBE) scheme and applying the frequency-degenerate vibrational model, the impacts of 5d electron binding energy and electron-phonon coupling on luminescence of Ce³⁺ in LYBO are analysed. The results show that the Ce³⁺ emission in LYBO possesses a moderate intrinsic thermal stability. With the increase in concentration, the thermal stability of the emission gets worse due to the possible thermally-activated concentration quenching. In addition, the simulation of Ce³⁺ emission profile at low temperature reveals that the 4f-5d electronic transitions of Ce³⁺ ions can be treated to couple with one frequency-degenerate vibrational mode having the effective phonon energy of ∼257 cm^-1 with the corresponding Huang-Rhys parameter of ∼6, which indicates a strong electron-phonon interaction of Ce³⁺ luminescence in the Li₆Y(BO₃)₃ host. Finally, the X-ray excited luminescence spectrum of the LYBO:5%Ce³⁺ phosphor is measured to check the potential scintillator applications.