Temperature dependence on the cross-relaxation rates in Tm3+ doped strontium fluorapatite

The cross-relaxation dynamics of Tm3+-doped strontium fluorapatites (S-FAP) has been examined using time-resolved fluorescence spectroscopy. The temperature dependence of the fluorescence lifetime crystal suggests a dipole–dipole interaction between the Tm3+ ions and the energy is transported by an incoherent hopping mechanism. The temperature dependence of the fluorescence lifetime suggests this incoherent hopping mechanism is used to bridge the energy mismatch between emission from the donor and the energy required for absorption by the acceptors. Using the energy transfer model of Agranovich, the cross-relaxation rate was determined from the emission decay dynamics of the 3H4→3H6 transition. The observed cross-relaxation rate ranged from 11 s−1 at 10 K to 81 s−1 at 200 K for 0.21 at% Tm3+ in S-FAP an energy barrier of 44.3 cm−1. The model suggest that rates of 106 ion hops s−1 for 1 at% Tm3+ in S-FAP could be achieved, rendering this material a potentially efficient laser medium.