Physical chemistry chemical physics : PCCP

A Pr3+ doping strategy for simultaneously optimizing the size and near infrared persistent luminescence of ZGGO:Cr3+ nanoparticles for potential bio-imaging.

PMID 28721421


Spinel-phase Zn2Ga2.98-xGe0.75O8:Cr0.020,Prx (ZGGO:Cr3+,Pr3+) near infrared (NIR) persistent luminescence nanoparticles (PLNPs) with different amounts of Pr3+ dopant were prepared by a hydrothermal method in combination with a subsequent annealing in a vacuum. For these nanoparticles, the averaged particle size decreases from 64 to 37 nm with increasing Pr3+ doping concentration from 0 to 0.025 and Cr3+ and Pr3+ ions are uniformly doped into the interior and surface of a single nanoparticle. It can be found that Pr3+ doping leads to the appearance of more anti-site pairs () around distorted octahedral Cr3+ ions and enhanced NIR emissions around 697 nm, which originate from the 2E(2G) → 4A2(4F) and 4T2(4F) → 4A2(4F) transitions of the interior and surface Cr3+ ions in the nanoparticles. In particular, for the interior Cr3+ ions in the Pr3+ doped nanoparticles, the enhanced NIR luminescence can be attributed to the suppressed energy transfer of the excited electrons from the 4T2(4F) level to the trap level related to anti-site pairs () around the distorted octahedral Cr3+ ions. Our results suggest that Pr3+ doped ZGGO:Cr3+ PLNPs have potential applications for bio-imaging.