Trapping processes in CaS:Eu2+,Tm3+

Abstract

CaS:Eu 2+ ,Tm 3+ is a persistent red phosphor. Thermoluminescence was measured under different excitation and thermal treatment conditions. The results reveal that the charge defects, created by substituting Tm3+ for Ca2+, serve as hole traps for the afterglow at room temperature. Tm3+ plays the role of deep electron trapping centers, capturing electrons either through the conduction band or directly from the excited Eu2+ ions. These two processes, in which two different sites of Tm3+ are involved, correspond to two traps with different depths.

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

“…For example, red persistent luminescence has been observed in CaS:Eu,Tm [15] and Ca 2 SiS 4 :Eu,Nd [16,17]. Recently, the family of alkaline earth nitrido-silicates, M 2 Si 5 N 8 :Eu (M = Ca, Sr, Ba) and their Tm-codoped variants were studied [10].…”

A new blue phosphorescent glass–ceramic: Rare-earth-doped calcium aluminoborate

“…For all the known LLP materials, Eu 2+ is the most important activation ion. Because the 5d electron of Eu 2+ is strongly coupled with the lattice of the host, the phosphorescence of Eu 2+ usually changes with its host, for example, red emission in CaS [13], green in SrAl 2 O 4 [1] and blue in CaAl 2 O 4 [1]. The same interpretation is rational for the red shift of the emission of Eu 2+ from CAEN (peaking at 440 nm) to CABEN (at 464 nm).…”

Synthesis and luminescent properties of a novel bluish‐white afterglow phosphor, b‐Zn3(PO4)2:Hf4+

“…Figure 3B shows the afterglow spectra of 5% Hf 4+ -doped β-Zn 3 (PO 4 ) 2 after the excitation source is stopped at different times (t = 5, 15, 35, 75 s). It is well known that trapping centres play an essential role in photo-energy storage in persistent, photostimulated and thermostimulated phosphors (10,18). Usually, the corresponding information about the trapping level can be obtained by TL measurements; the shallower the trap depth, the lower the temperature of the TL peak (19).…”