[Cooperative downconversion in Tb (0.7 ) Yb (5) : FOV oxyfluoride nanophase vitroceramics]

The present article reports the infrared quantum cutting study of the nanophase oxyfluoride vitroceramics Tb(0.7)Yb (5.0) : FOV. The visible to infrared fluorescence emission spectra, excitation spectra and fluorescence lifetime were measured carefully. The infrared quantum cutting phenomenon {1([5 D4 --> 7 F6](Tb3+), 2([2 F7/2 --> 2 F5/2](Yb3+)} was analyzed based on the above experiments. It was found that the theoretical quantum cutting efficiency is about 121.35% when 5D4 level is excited by 487.0nm light, and about 136.27% when (5D3, 5G6) levels are excited by 378.0 nm light respectively. Meanwhile, it is first time for the present paper to find a cooperative downconversion phenomenon {2([(5D3, 5G6) --> 5D4] (Tb3+), 1([2 F7/2 --> 2 F5/2] (Yb3+)}. That is, the authors found for the first time that the donor Tb3+ ion releases two pieces of energy [(5D3, 5G6) --> 5D4] of small energy photon to produce a middle energy photon [2 F5/2 --> 2 F7/2] of acceptor Yb3+ ion.