Discovery of the Persistent Luminescence Mechanism of CdSiO₃:Tb³⁺

Abstract

The persistent luminescence of CdSiO 3 :Tb 3+ was investigated with photoluminescence, thermoluminescence (TL), synchrotron radiation X-ray absorption (XANES and EXAFS) and UV-VUV spectroscopies. Only the typical intraconfigurational 4f 8 −4f 8 transitions of the Tb 3+ ion were observed with no traces of band emission in either the conventional UV excited or persistent luminescence spectra. The trap structure from TL with three traps from 0.65 to 0.85 eV is ideal for room-temperature persistent luminescence similar to, e.g., Sr 2 MgSi 2 O 7 :Eu 2+ ,R 3+ . Despite the rather low band gap energy, 5.28 eV, the persistent luminescence from Tb 3+ is produced only under UV irradiation due to the inauspicious position of the 7 F 6 ground level deep in the band gap of CdSiO 3 . This confirms the role of electrons as the charge carriers in the mechanism of Tb 3+ persistent luminescence. The XANES spectra indicated the presence of only the trivalent Tb 3+ species, thus excluding the direct Tb 3+ → Tb IV oxidation during the charging process of persistent luminescence. Eventually, a unique persistent luminescence mechanism for Tb 3+ in CdSiO 3 was constructed based on the comprehensive experimental data.

The importance of inversion disorder in the visible light induced persistent luminescence in Cr3+doped AB2O4(A = Zn or Mg and B = Ga or Al)

“…This makes it a versatile tool to study persistent luminescent materials since the dopant concentration will usually be very low. [18][19][20][21][22][23][24][25][26][27][28] …”

In Vivo Repeatedly Charging Near‐Infrared‐Emitting Mesoporous SiO2/ZnGa2O4:Cr3+ Persistent Luminescence Nanocomposites

“…[4–6] Until now, persistent luminescence has relied on short-wavelength excitation (e.g., ultraviolet light) which has rather limited tissue-penetration depth. [7–10] To address this problem, a NIR-light-stimulated PL mechanism was proposed in LiGa 5 O 8 :Cr 3+ , to release energy trapped in deeper energy levels of the phosphor, but in this case, the energy must be precharged by UV-light and the photostimulated emission continues to weaken after each cycle of photostimulation and will finally become extinguished. [3,11] Very recently, the PL phosphor, ZnGa 2 O 4 :Cr 3+ (ZGC), was found to be activatable by using tissue-penetrable red light, which means that energy can be recharged and NIR PL imaging is no longer limited by the luminescence-decay life-time of the phosphor.…”

Order and disorder around Cr3+ in chromium doped persistent luminescent AB2O4 spinels

“…22 However this valence state change was disproved by the same group when they observed no signature of Eu 3+ oxidation state in the XANES spectra. 23 25 In a previous paper, we had presented EXAFS results along with optical and electron paramagnetic resonance (EPR) studies on Cr 3+ doped AB 2 O 4 spinels (A=Zn, Mg and B=Ga, Al). 17 In there, the crucial role of inversion defects in necessitating the persistent luminescence in spinels specially with visible light excitation was illustrated in detail.…”