Dynamical aspects of the core excitons formed by the 4f–4f transitions of Gd 3+ in Gd 2SiO 5

Abstract

Comparing the luminescence spectra with the absorption spectra of the core excitons formed by the 4f–4f transitions of Gd 3+ in Gd 2SiO 5, 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 μs 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 Eu 3+ 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 Gd 2SiO 5.