Dynamical aspects of the core excitons formed by the 4f-4f transitions of Gd3+ in Gd2SiO5

Comparing the luminescence spectra with the absorption spectra of the core excitons formed by the 4f-4f transitions of Gd3+ in Gd2SiO5, we investigate the dynamical aspects of the core excitons. It is concluded that the core excitons are bound to defects at low temperatures, and excited thermally to the free state to migrate in a long distance over 70 nm at high temperatures. The decay times of the core excitons are measured to be 130 mu s and 1.1 ms in the free state and bound state, respectively. The migration of the core excitons and the transfer of the energy to impurities such as Eu3+ are discussed on the basis of the electric quadrupole-quadrupole interaction for the core excitons. This is the first report for the dynamical aspects of the core excitons in pure Gd2SiO5. (C) 2000 Elsevier Science B.V. All rights reserved.