Spectroscopy and Luminescence Dynamics of Ce³⁺ and Sm³⁺ in LiYSiO₄

Abstract

The lithium yttrium silicate series of LiY1–x Ln x SiO4 exhibits superb chemical and optical properties, and with Ln = Ce3+, Sm3+, its spectroscopic characteristics and luminescence dynamics are investigated in the present work. Energy transfer and nonradiative relaxation dramatically influence the Ln3+ luminescence spectra and decay dynamics, especially in the Ce3+–Sm3+ codoped phosphors. It is shown that thermal-quenching of the blue Ce3+ luminescence is primarily due to thermal ionization in the 5d excited states rather than multiphonon relaxation, whereas cross-relaxation arising from electric dipole–dipole interaction between adjacent Sm3+ ions is the leading mechanism that quenches the red Sm3+ luminescence. In the codoped systems, Ce3+–Sm3+ energy transfer in competing with the thermal quenching enhance the emission from Sm3+. The combined influences of concentration quenching, thermal ionization, and energy transfer including cross-relaxation on the luminescence intensity of single-center and codoped phosphors are analyzed based on the theories of ion–ion and ion–lattice interactions.

Mechanistic Insight into Energy‐Transfer Dynamics and Color Tunability of Na4CaSi3O9:Tb3+,Eu3+ for Warm White LEDs

“…7 F 5 (Tb 3 + ) + 5 D 1 (Eu 3 + ), DE % 180 cm À1 ]a nd [ 5 D 4 (Tb 3 + ) + 7 F 0 (Eu 3 + ) ! 7 F 4 (Tb 3 + ) + 5 D 0 (Eu 3 + ), DE % 70 cm À1 ]a nd the large phonon energy of silicate in the general cases, [16] Tb 3 + ! Eu 3 + ET is expected to occur in the system.I nt he early 1990s, several studies investigated the ET mechanisms of Tb 3 + and Eu 3 + in cubic hexachloroelpasolites Cs 2 NaLnCl 6 lattices, including multipole interactions, transfer selection rules, transfer pathways, phonon-assisted contributions, and possible energy migration effects.…”

VUV/Vis Photoluminescence, Site Occupancy, and Thermal‐Resistance Properties of K4SrSi3O9:Ce3+

“…where I (0) is the intensity at t= 0, t 0 the donor decay time in the absence of acceptor, Q the macroscopic parameter that determines the effect of multipolar interaction on the decay property, and s the multipolar effect parameter, where s =6, 8, and 10 represent the dominant mechanism's being electric dipole–dipole (EDD), electric dipole‐quadrupole, or electric quadrupole‐quadrupole interaction, respectively. For the purpose of defining the type of multipolar effect, the experimental decay curves were fitted by using Equation and the fitting results are plotted in Figure c: …”

Optical transition and luminescence properties of Sm3+‐doped YNbO4 powder phosphors

“…The similar tendency of each fluorescence decay means that the energy transfer processes between Sm 3+ almost have no change at various temperatures. Thus, it is speculated that the temperature‐dependent energy transfer has little influence on the luminescence thermal quenching of Sm 3+ . In addition, due to the large energy gap (7421 cm −1 ) between 4 G 5/2 and 6 F 11/2 levels, the multi‐phonon cascade nonradiative relaxation is impossible to occur.…”

“…Thus, it is speculated that the temperature-dependent energy transfer has little influence on the luminescence thermal quenching of Sm 3+ . 35 In addition, due to the large energy gap (7421 cm −1 ) between 4 G 5/2 and 6 F 11/2 levels, the multi-phonon cascade nonradiative relaxation is impossible to occur. That is, the nonradiative relaxation is not responsible for the luminescence thermal quenching behavior of Sm 3+ in YNbO 4 : Sm 3+ phosphors.…”