Low-temperature irradiation effects in lithium orthosilicates

The emission spectra of lithium orthosilicates (Li4SiO4) ceramics have been measured in the range of 1.8–5.8 eV under irradiation by 6–30 eV photons or 1–30 keV electrons at 6–300 K. The tunnel recombination phosphorescence, as well as luminescence, stimulated by 1.5–2.5 eV photons has been detected in the sample preliminarily irradiated at 6 or 80 K. The main peaks of thermally stimulated luminescence (TSL) in the irradiated ceramics have been observed at 72, 118 and 265 K. The creation spectra of the 118 K TSL peak, as well as the excitation spectrum of photostimulated luminescence (PSL) span the region of the intrinsic absorption of a lithium orthosilicate (9–30 eV). The intensity of PSL and the TSL peaks in Li4SiO4 ceramics prepared in hydrogen/argon atmosphere is several times lower than that in the mainly investigated Li4SiO4 ceramics prepared in the atmosphere of dry argon. The optical characteristics of Li4SiO4 are compared with the ones known for Li2O and SiO2. Low-temperature luminescent methods are promising for the investigation of electron–hole processes and radiation defects serving as the traps for tritium released in D–T fusion reactor blanket systems.