Li + and Er 3+ codoped Y 2 O 3 powders are synthesized via sol-gel method. The effects of Li + doping on the optical properties of Er 3+ :Y 2 O 3 are investigated under 980 nm excitation. The emission intensity of Er 3+ is obviously improved after Li + doping. Moreover, the quenching concentration of 2 H 11/2 / 4 S 3/2 level of Er 3+ is 3.0 mol% for the samples without Li + but it decreases to 2.0 mol% after introducing 5.0 mol% Li + . This is because Li + doping shrinks the host lattice and decreases the Er 3+ -Er 3+ distance, which contribute to the formation of Er 3+ clusters and thus induces the quenching concentration of 2 H 11/2 / 4 S 3/2 level to decrease. Int. J. Mod. Phys. B 2014.28. Downloaded from www.worldscientific.com by Mr. du zhong on 02/03/15. For personal use only.
Er3+, Yb3+ codoped ZrO2 nanocrystalline powders were prepared by chemical co-precipitation. We determined the crystal structures and the room temperature upconversion emission properties of samples with different doping concentrations of Yb3+ and at different sintering temperatures, respectively. It is shown that the monoclinic phase increases with the sintering temperature and the tetragonal phase increases with the increasing of Yb3+ concentration. We found that the green emission intensity and the red emission intensity of the samples sintered at 800℃ were enhanced with the increasing of Yb3+ concentration, but the red emission intensity increased much more. The quadratic dependence of the green and the red emissions on excitation power indicates that a two-photon absorption process occurs under 976nm excitation. The infrared emission properties were also discussed in the present paper.
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