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Tb3+ ion luminescence enhancement in yttria host lattice obtained via microwave hydrothermal process
|Jarosław Kaszewski , Sergiy A. Yatsunenko , Ewelina A. Wolska , Bartłomiej S. Witkowski , Łukasz Wachnicki , Marek Godlewski|
Institute of Physics, Polish Academy of Sciences, Warsaw 02-668, Poland
Yttrium oxide is very attractive optical material considering its properties: low optical loss, low phonon energies, high refractive index and wide band gap. And since the non-radiative relaxation from excited states is not efficient in Y2O3, the material is suitable as host lattice for optically active lanthanide ions. Yttrium oxide can be easily doped with the ions such as Tb3+, Pr3+ and Eu3+ having characteristic emission lines in visible region.
In our study, the growth of Y2O3:Tb was conducted via microwave driven hydrothermal process. It was found that as prepared material did not contain pure cubic yttrium oxide phase, the hydroxides, oxohydroxides and nitrate complexes were also present. The annealing cycles were performed to show material crystallization evolution. The crystallites were found to be strongly agglomerated into needle-like aggregations. The characteristic trivalent terbium emission lines from 5D4 and 5D3 sublevels to 7FJ were observed in all the samples. The Tb3+ ion shows spectrally narrow green emission bands in Y2O3, excited at relatively low energy, due to 4f8→4f75d intra-ionic transition. After annealing an increase of intensity of the luminescence emission was observed. Interestingly, the mechanism of the trivalent terbium excitation has changed after calcination. The as grown samples exhibit the series of 4f intra-shell excitation lines with the maximum at 413 nm. On the other hand, the annealed samples have shown the host lattice - lanthanide ion coupling resulting in the appearance of the broad charge transfer bands at 306 and 337 nm. Such activation of the Tb3+ ions is related to the growth of the yttria crystallites and changes in dopant coordination.
Presentation: Oral at Nano PL 2014, Symposium A, by Jarosław Kaszewski
See On-line Journal of Nano PL 2014
Submitted: 2014-07-02 05:40 Revised: 2014-07-03 08:06