In situ luminescence measurement at high temperature from Li2O under neutron irradiation

During reactor Irradiation of Li2O, the defects are introduced by neutrons, tritons and helium ions produced by Li-6(n,alpha)H-3 reactions, and gamma-rags. It is well known that the radiation defects influence the tritium release process. The in situ luminescence emission (LE) measurements have been performed for Li2O single crystal at the research reactor 'YAYOI' of the University of Tokyo in order to study the behavior of radiation defects under various conditions (temperature, sweep gas chemical composition and neutron spectrum). The LE was observed at the wavelength from 250 to 600 nm at 298-873 K. The luminescence spectra were found to consist of five emission bands. The luminescence emissions at 340 nm (3.65 eV), 375 nm (3.31 eV) and 430 nm (2.88 eV) were assigned to the F-O, F+ and F-2 centers, respectively. The emission band at 510 nm (2.43 eV) was thought to be due to the F-2 center affected by a hydroxide group. The origin of the luminescence band at 305 run (4.06 eV) could be related to an intrinsic defect or impurity luminescence. A mechanism of the defects creation and the luminescence emission is discussed. (C) 1997 Elsevier Science B.V.