Persistent luminescence (PersL) phosphors are considered as promising candidates for the next generation of information storage medium. Mg 4 Ga 4 Ge 3 O 16 (MGG) is an electron trapping material which exhibits defect luminescence, and the luminescent properties are easily tuned via doping various activated ions. In this work, undoped and Mn 2+ /Pr 3+ /Tb 3+ single-doped MGG phosphors were synthesized via high temperature solid phase reactions. X-ray diffraction and scanning electron microscope results confirm that the activated ions tend to occupy Mg 2+ sites. Excited at 265 nm, the MGG host exhibits a defect emission band peaked at 450 nm. Red, pink and green emissions are observed in the Mn 2+ /Pr 3+ /Tb 3+ single-doped MGG samples, which are ascribed to the Mn 2+ : 4 T 1 (G) → 6 A 1 (S), Pr 3+ : 1 D 2 → 3 H 4 and Tb 3+ : 5 D 4 → 7 F 5 transitions, respectively. All the samples exhibit bright PersL for minutes after the cessation of excitation. The energy transfer, concentration quenching, luminescence decay and afterglow mechanisms are also discussed in detail. The phosphors exhibit efficient thermal and optical stimuli response, showing great potentials in the optical information storage.
Dangli Gao,Qingqing Kuang,Feng Gao,Hong Xin,Sining Yun,Yuhua Wang
Optical characteristics of phosphors, e.g. color output, decay process and external field stimulation mode (including opto-, thermo- and mechano-stimulation), play an important role in the areas of information storage, anti-counterfeiting and bio-imaging applications. Persistent luminescence (PersL) phosphors are particularly suitable for such applications owing to their multimodal luminescence features such as photoluminescence (PL), PersL, photostimulated luminescence and mechanoluminescence. However, conventional PersL phosphors are suffering from a huge challenge to develop a single material for multicolor anti-counterfeiting. Herein, the Zn 1+ x Ga 2−2 x Ge x O 4 :Mn (0 ≤ x ≤ 1) solid solution phosphors are synthesized, which can emit from green to yellow, golden, pink, and red PL. In addition, the phosphors also show the thermo-mechano-opto-stimulated green PersL after irradiation of a UV 254/365 nm lamp. Based on the multimode and multicolor luminescence features, the advanced anti-counterfeiting and optical data storage are designed. Results show that the multimodal luminescence feature with high information capacity can be conveniently identified by using a luggable ultraviolet lamp or NIR laser diode. This extraordinary material will make anti-counterfeiting more sophisticated and show advanced security in the applications of data encryption.
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