Reversible white-brown photochromism in a self-activated long-persistent phosphor Mg_2SnO_4

Recent advances and prospects of persistent luminescent materials as inner secondary self-luminous light source for photocatalytic applications

“…[164], (iii) excitation and emission spectra of Zn3Al2Ge2O10:0.01Cr 3+ [177], and (iv) excitation and emission spectra of ZnGa2O4:Cr 3+ ,Bi 3+ and ZnGa2O4:Cr 3+ pellets [196]; (b) (i) Digital photos and NIR images of Zn3Ga2GeO8:Cr 3+ (left) and Figure 6 Persistent spectra of (a) CaZnGe2O6:Mn 2+ recorded from 1 min to 8 min [199], (b) γ-Zn3(PO4)2:Mn 2+ ,Ga 3+ [203] xBi 3+ and the relationship between the persistent intensity and the Bi 3+ content (inset) [260], (ii) intensity-normalized photoluminescence (PL), long-lasting (LPL), and photostimulated (PSL) spectra of CaGa2O4:Bi 3+ and a photo (inset) [269], and (iii-iv) persistent spectra of Sr2.997Bi0.003Ga4O9 from 30 s to 246 min [261]; (b) Photographs of (i) Sr2.985Bi3xGa4O9 taken within the range of 0-600s after removal of 254 nm UV lamp [261], and (ii) LiYGeO4:Bi 3+ in the range of 24-300 h and its relevant PSL luminescent images under 980 nm, 808 nm, and a red LED irradiation and taken after 300 h (bottom row) [265]; (c) (i) Persistent spectrum of CdSiO3:Pb 2+ [270], (ii) florescence spectra of CaO:Pb 2+ (A) and SrO:Pb 2+ (B) and persistent spectrum of SrO:Pb 2+ (C) [271], (iii) persistent spectra of Sr2MgGe2O7:Pb 2+ [273]. Figure 9 (a) (i) Excitation, photoluminescence (PL) and persistent spectra of SrZrO3 [319], (ii) PL (1) and the persistent (PerL) spectra of SrZrSi2O7 sintered in reducing atmosphere (2) and air (3), the insets are persistent (left) and PL images (right) of the sample [328], (iii) persistent spectra of Na2(Zn1-xGax)GeO4 and the image of Na2(Zn0.8Ga0.2)GeO4 after removal of femtosecond laser (inset) [329], (iv) normalized PL and persistent spectra of ZrO2 [331]; (b) Persistent images of (i) Mg2SnO4 [320], and (ii) MgGa2O4 [322], (iii) PL colors of bazirite-type BaZr1-xTixSi3O9 under 254 nm and 312 nm light and persistent images of a pabstite-type BaSn1-yTiySi3O9 [327]. Figure 10 (a) Upconverting persistent spectrum of Zn3Ga2GeO8:Cr 3+ ,Yb 3+ ,Er 3+ phosphor and its decay curve monitored at 700 nm peak (inset, upper right) and NIR images (inset, upper left) [40]; (b) Upconversion fluorescent spectra of the β-NaYF4:Yb,Er/NaYF4 membrane achieved with different 980 laser powers [343]; (c) Emission spectra of NaCa2GeO4F:0.2%Mn 2+ ,xYb 3+…”

Fine-Tunable Self-Activated Luminescence in Apatite-Type (Ba,Sr)5(PO4)3Br and the Defect Process

“…). − The latter includes vacancies, self-interstitials, and antisites and forms defect levels within the band gap acting as recombination centers and giving rise to visible light emissions at specified wavelengths . Defect-related luminescence has been examined for decades in oxide-, chalcogenide-, and nitride-based semiconductors, such as ZnO, CdSe, GaN, Ca 3 B 2 N 4 , Mg 2 SnO 4 , etc., where the defect emissive centers have been extensively studied and widely accepted. However, in recent years, unique defect luminescence has been discovered in oxysalts such as oxyfluoride Sr 3– x A x MO 4 F (A = Ca or Ba; M = Ga or Al), fluosilicate La 3 F 3 [Si 3 O 9 ] and Ca 4 F 2 Si 2 O 7 , phosphate α-Zn 2 P 2 O 7 and BPO 4 , apatite-type M 5 (PO 4 ) 3 OH (M = Ca or Sr), , Ca 5 (PO 4 ) 3 F and Ca 2 Ba 3 (PO 4 ) 3 Cl, etc.…”

Structures, photoluminescence, and principles of self-activated phosphors

“…The electron or hole-trapped defects generated by photo-stimulation are considered to be closely related to photochromics. 17 The charge transfer in the defective centers is shown in Fig. 3.…”