Enhanced upconversion in Dy3+, Yb3+ co-doped Gd2O3 monodisperse nanocrystals
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Dy3+/Yb3+ co-doped Gd2O3 monodispersed nanocrystals have been synthesized using the sodium dodecyl benzene sulfonate (SDBS) as the surfactant. The SDBS surfactant plays a critical role in the forming of monodisperse Gd2O3 structures with sphere-like morphologies. The growth mechanism of the nanocrystals was proposed in detail. The samples annealed at 400 °C for 4 h exhibit good crystallinity and narrow size distribution with average size of 6–9 nm. Green and red emission of Dy3+ related to 4G11/2–6H11/2 and 4G11/2–6H9/2 transition was observed under the laser excitation at 980 nm. An involvement of three photons has been observed for these emissions. The energy distribution of upconversion spectra depended on doping concentration and the intensity changed with the increasing of Dy3+ concentration. The mechanisms of upconversion by multi-photon absorption and energy transfer processes transitions were interpreted and explained.
KeywordsGd2O3:Dy3+, Yb3+ nanocrystals Upconversion Energy transfer Growth mechanism
This work was financially supported by the National Natural Science Foundation of China (51302330), Science and Technology Research Foundation of the Education Commission of Chongqing City (KJ1501132), Chongqing Natural Science Foundation (cstc2015jcyjA50013), Talent Introduction Project of Chongqing University of Arts and Science (Nos. R2012CJ17, Y2013CJ25 and R2012CJ19) and new Material Development and Application Innovative Research Team of Higher Education in Chongqing of China (Grant No. 201042).