Vacuum Referred Binding Energy Scheme, Electron–Vibrational Interaction, and Energy Transfer Dynamics in BaMg₂Si₂O₇:Ln (Ce³⁺, Eu²⁺) Phosphors

Abstract

The host structure and the synchrotron radiation VUV–UV luminescence properties of samples BaMg2Si2O7 (BMSO):Ln (Ce3+, Eu2+) at different doping levels and different temperatures were investigated in detail. Three important aspects are studied to elucidate the luminescence properties of samples: (1) the vacuum referred binding energy (VRBE) scheme is constructed with the electron binding in the BMSO host bands and in the Ce3+ and Eu2+ impurity levels with the aim to explain the different thermal stabilities of Ce3+ and Eu2+ emissions; (2) the electron–vibrational interaction analysis on the narrow Eu2+ emission indicates a weak electron–phonon interaction in the current case; (3) by using three models (Inokuti–Hirayama, Yokota–Tanimoto, and Burshteĭn models) at different conditions, the energy transfer dynamics between Ce3+ and Eu2+ was analyzed. It reveals that the energy transfer from Ce3+ to Eu2+ via electric dipole–dipole (EDD) interaction is dominant while energy migration between Ce3+ is negligible. Finally, the X-ray excited luminescence spectra of samples BMSO:Ce3+/Eu2+ are collected to evaluate their possible scintillator applications.

VUV–UV–vis Luminescence, Energy Transfer Dynamics, and Potential Applications of Ce3+- and Eu2+-Doped CaMgSi2O6

“…Consequently, the exciton creation energy ( E ex ) of CaMgSi 2 O 6 can be estimated to be ∼7.85 eV. This value is comparable to that of alkaline earth silicates BaMg 2 Si 2 O 7 (∼7.65 eV) and BaCa 2 MgSi 2 O 8 (∼7.42 eV) but slightly higher than those of Ba 3 MgSi 2 O 8 (∼7.12 eV) and Ba 2 MgSi 2 O 7 (∼6.89 eV) in energy. − Accordingly, the band gap energy of CaMgSi 2 O 6 can be evaluated by the sum of host exciton creation energy ( E ex ) and the exciton binding energy . Two empirical approaches have been proposed to estimate the exciton binding energy.…”

Site Occupancies, VUV-UV–vis Photoluminescence, and X-ray Radioluminescence of Eu2+-Doped RbBaPO4

“…[11][12][13] Thirdly, the investigations on the energy-transfer dynamics through fluorescence decays are beneficial to understand the luminescence processes. 14,15 The compound RbBaPO4 belongs to ABPO4 (A is an alkali metal, B is an alkali earth metal) type orthophosphates, it has good thermal, hydrolytic stability and wide band gap. [16][17][18][19][20][21] On the basis of systematic studies on the VUV-UV-vis photoluminescence and X-ray radioluminescence of Eu 2+ doped RbBaPO4, in this paper we report a potential X-ray phosphor RbBa0.995Eu0.005PO4 after discussions on the site occupancies, the EVI and the energy-transfer dynamics in detail.…”

Suppression of Eu2+ Luminescence Loss

“…[ 36 ] To evaluate its potential impact on Eu 2+ luminescence in the current system, one spectroscopic data‐based approach [ 37 ] is adopted to generate the energy level scheme of Eu 2+ ‐doped SMPO, and the reliability of this approach has been widely approved. [ 24a,38 ] As the bases of scheme construction, the transition properties of Ce 3+ and Eu 3+ in SMPO were initially collected. With 326 nm Ce 3+ 5d 1 →4f emission (Figure S6a, Supporting Information), five excitation bands attributing to Ce 3+ 4f‐5d 1‐5 transitions are detected in the excitation spectrum ( Figure a), and the host absorption peaking at 8.08 eV is observed.…”

“…As a typical embodiment, the extent of line broadening of Eu 2+ luminescence indicates the degree of contribution of vibration to 4f‐5d transition properties of Eu 2+ . [ 41 ] On the state of the Huang−Rhys theory assuming the exclusive participation of the single vibration mode, [ 24a,29,42 ] the low‐temperature spectral profile of Eu 2+ 5d→4f emission in the diluted‐doped SMPO is simulated (Equation S4, Supporting Information), and the result is given in Figure a. The energy of zero‐phonon line ( E ZPL ) of Eu 2+ 4f‐5d transition is determined to be 3.27 eV.…”

“…Besides, a large separation of the excited states of activator to the CBM of host is crucial for diminishing the deleterious impact of ionization, while the comparable luminescence efficiencies of Ce 3+ and Eu 2+ as residing in the identical site of lattice are commonly witnessed even though the difference in mutual location of 5d state to the CBM in two cases is significant. [ 24 ] Given these ambiguities, it appears that the current understanding on the luminescence efficiency of Eu 2+ ‐doped material is still inadequate, and the comprehension needs to rise from novel perspectives. Herein, the analysis on the efficiency loss mechanism is launched on Eu 2+ ‐doped SrMgP 2 O 7 (abbreviated as SMPO later) which owns the superior properties of narrow‐band luminescence and near‐unity internal quantum yield (IQY).…”