Energy transfer in rare earth doped Y3Al5O12 at very high temperatures

Phonon assisted energy transfer from the F-2(5/2) state of Yb3+ to the F-7(0) state of Tb3+ in Y3Al5O12 has been investigated up to 1850K. Together with prior data from the literature, the results suggest that the temperature dependence of the energy transfer probability over the entire range is well described by the electron coupling to phonon modes at the two ends of the spectrum only. Additionally, it is found that the electron-phonon coupling parameter for the lowest energy phonons is an order of magnitude larger than that for those with the highest energy. (C) 2002 Elsevier Science B.V. All rights reserved.