Spectral Hole-burning Properties of LiGa5O8:Co2+ Nanocrystallites

Properties of persistent spectral holes in the 4A2(F)←4T1(P) transition in nanocrystalline (20–100 nm) powders and in single crystals of LiGa5O8:Co2+ have been investigated. It appears that for the investigated samples, the hole-burning efficiency is higher and spectral diffusion more pronounced in the nanocrystalline sample. Holes can efficiently be erased by exposure to 532 nm light but the 4A2(F)←4T1(P) luminescence appears to be stable when excited at this wavelength. Results indicate that the holeburning mechanism is based on the presence of Co3+ ions which act as electron traps upon selective photoionization of the Co2+ ions.