| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 5399656 | Journal of Luminescence | 2014 | 8 Pages |
Abstract
Yb3+/Er3+ codoped yttrium aluminium garnet (YAG) porous nanocrystals were prepared by glycolate method assisted with poly-vinyl alcohol (PVA) and urea. The typical cubic structure for YAG was confirmed from XRD with crystallite average size of ~40Â nm, calculated from Scherrer formula and corroborated by TEM. Strong green and red upconversion emissions are observed readily with the naked eyes, and the color coordinates were obtained from emission spectra. A theoretical model to calculate CIE coordinate as a function of donor (Yb3+) and acceptors (Er3+) concentration is proposed. The eye-safe near infrared emitted signal and fluorescence lifetime were also measured and results show lifetime as large as 8.5Â ms. The maximum energy transfer efficiency from Yb3+ to Er3+ was 72% for 20Â mol% of Yb2O3. The proposed mechanisms for signal emitted are explained in terms of direct and energy back transfer processes, and cross relaxation.
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Authors
H. Desirena, L.A. Diaz-Torres, R.A. RodrÃguez, O. Meza, P. Salas, C. Angeles-Chávez, E.H. Tobar, J. Castañeda-Contreras, E. De la Rosa,