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On the mechanism of persistent up-conversion luminescence in the ZrO2:Yb3+,Er3+ nanomaterials

2014; Elsevier BV; Volume: 36; Issue: 10 Linguagem: Inglês

10.1016/j.optmat.2014.01.027

1873-1252

Laura Pihlgren, Tero Laihinen, Lucas Carvalho Veloso Rodrigues, Stefan Carlson, Kari O. Eskola, Aleksei Kotlov, Mika Lastusaari, Tero Soukka, Hermi F. Brito, Jorma Hölsä,

Glass properties and applications

The up-converting ZrO2:Yb3+,Er3+ nanomaterials were prepared with the combustion and sol–gel methods. The structure of the materials was cubic except for the minor monoclinic and tetragonal impurities associated with the use of the sol–gel method. The XANES results revealed only the trivalent form for both the Yb and Er dopants. The distance distributions calculated from EXAFS confirm that Er3+ and Yb3+ occupy the ZrIV site in the structure. The nanomaterials show red (650–700 nm) and very weak green (520–560 nm) up-conversion luminescence due to the 4F9/2 → 4I15/2 and (2H11/2,4S3/2) → 4I15/2 transitions of Er3+, respectively. The nanomaterials obtained with the combustion synthesis yield the most intense luminescence though showing significant afterglow, as well. The thermoluminescence measurements revealed the existence of traps with depths between 0.68 and 1.03 eV well matching to room temperature persistent emission. Finally, the mechanism for the persistent up-conversion luminescence was introduced based on the experimental results and discussed.