Ni doped ZnS nanopowders were synthesized by hydrothermal method. The as-synthesized ZnS nanopowders possessed zinc blende structure with the particle sizes of ∼20 nm, and they display a broad emission band from 400 nm to 700 nm centered at ∼540 nm. The influence of Ni 2+ doping and vacuum annealing on the structure, morphology and optical properties was investigated systematically. The results revealed that the emission peaks are blue shifted with Ni 2+ doping, and the emission peaks of 0.2, 0.4, 0.6, 0.8 and 1.0 mol% Ni 2+ doped ZnS nanopowders are centered at ∼520, ∼ 510, 500, 490 and 470 nm, respectively. While, the zinc blende phase transformed to wurtzite phase when annealing at 600 °C or higher, and the annealed samples exhibited three emission peaks positioned at ∼490, ∼547 and ∼580 nm. The results indicated that the as prepared Ni 2+ -doped ZnS nanopowders have a potential application in LED as light conversion layer.
Kailei Lu,Yucheng Ye,Ruichong Chen,Yilong Li,Jianqi Qi,Tiecheng Lu
A simple and efficient route for the coloration erasure and significant photoluminescence enhancement of lanthanide-doped transparent ceramics was novelly developed in this work. As for the illustrative examples, full-band high transparency and efficient luminescence of YZO:Tb and YZO:Pr ceramics were received after air annealing plus vacuum re-annealing processes. The defect clusters [ L n Y 4 + - O 2 − - L n Y 4 + ] and [ L n Y 4 + - e ′ ] were also proposed for the relevant reaction mechanisms involving air annealing and vacuum re-annealing processes. Insight in the vacuum re-annealing strategy might open up a path towards controllably tailoring the optical transmission and transition properties of lanthanide-doped highly transparent ceramics.
Jian Yang,Yuxue Liu,Duanting Yan,Hancheng Zhu,Chunguang Liu,Changshan Xu,Li Ma,Xiaojun Wang
Novel Cr3+ doped zinc gallogermanate (ZGGO) nanoparticles with 697 nm near-infrared (NIR) super long afterglow were prepared via a hydrothermal method. Subsequently, a vacuum-annealing strategy was adopted to improve NIR afterglow in ZGGO:Cr3+ nanoparticles. For the sample annealed at 800 °C, no variation in the particle size is observed, the persistent luminescence increases by an order of magnitude (∼14 times) and the NIR afterglow time reaches more than 15 hours relative to the as-prepared sample. After annealing at temperatures higher than 880 °C, the persistent luminescence of the nanoparticles is enhanced, but they show aggregated-surface behavior. Meanwhile, shallow and deep traps are generated, related to the antisite defects and VGe–Cr3+–VO defect clusters, respectively. Finally, we apply ZGGO:Cr3+ persistent luminescence nanoparticles (PLNPs) to a human serum albumin (HSA) colloid solution, and more than 1 h of NIR persistent luminescence is detected under 320 nm excitation. The quenching effect of NIR luminescence by OH− in the HSA solution is observed based on the reduced contribution of surface Cr3+ in PLNPs to NIR luminescence. Our results suggest that ZGGO:Cr3+ PLNPs have potential applications for in vivo bio-imaging.
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