Nanotech 2010

Precipitant molar concentration effect on the upconversion emission in BaZrO3:Er,Yb nanocrystalline phosphor

L.A. Diaz-Torres, P. Salas, V.M. Castaño, J. Oliva, C. Angeles-Chavez
Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, MX

Keywords: upconversion, nanocrystals, erbium, Ytterbium, hydrothermal method


Strong Blue, green, and red upconversion emission of Er3+ in sub-microcrystalline BaZrO3:(Yb3+Er3+) is observed. Powder samples were obtained by a facile hydrothermal process at 100ºC with different water to ethanol solvent ratios. The as synthesized nanocrystallites present a stable cubic perovskite phase only for a solvent ratio of 1:1, such behavior is preserved under subsequent annealing treatment up to 1000ºC. A slight phase segregation of rare earth oxides is observed for solvet ratios different of 1:1. Under IR excitation in the range between 900 and 1050nm the Er3+ blue emission was almost not present in single Er3+ doped BaZrO3, whereas it became easily observable when Yb3+ was added as codopant. Besides, both green and red upconversion emission of Er3+ are enhanced by around three orders of magnitude in comparison with the single Er3+ doped BaZrO3. The strong blue emission presents dependence on excitation power, and excitation wavelength, and solvent ratio. A possible mechanism for the upconversion process that leads to the observed blue, green and red emissions under NIR excitation is suggested based on the experimental results.
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