Luminescence, radiation damage, and color center creation in Eu3+-doped Bi4Ge3O12 fiber single crystals

Doped Bi4Ge3O12 (BGO) fiber single crystals were grown by the micro-pulling-down method with the resistance heating system. Optical absorption measurements before and after x-ray irradiation (induced absorption) were performed in order to investigate the radiation damage of the crystals. The Eu3+-doped BGO has shown higher radiation resistance with respect to the equivalently grown undoped BGO fibers. Radio- and photoluminescence characteristics were obtained to clarify the role of Eu3+ in luminescence and scintillation mechanism. Radioluminescence spectra show the intense and slow (decay time of 1.61 ms) D-5(0,1)-F-7(x)(x=0-6) radiative transitions of Eu3+, while the intrinsic BGO emission becomes weaker with respect to the undoped BGO. Photoluminescence decay of the intrinsic BGO emission becomes nonexponential and noticeably faster in Eu-doped samples, which evidences the nonradiative energy transfer from intrinsic emission centers to Eu3+ ions. Thermally stimulated luminescence (TSL) measurements above room temperature prove that Eu3+ doping strongly influences the concentration of TSL active traps. (C) 2003 American Institute of Physics.