Correlation between the crystalline environment and optical property of Mn2+ ions in ZnGa2O4: Mn2+ phosphor

Abstract

Sol-gel-driven ZnGa2O4:Mn2+phosphors are annealed at various temperatures. As an increase of the annealing temperature of as-grown ZnGa2O4:Mn2+phosphors, their lattice constants and crystallinities are increased. The resonance signal intensity of Mn2+ ions on Td sites is drastically increased whereas that of Mn2+ ions on Oh sites is decreased as the annealing temperature is increased. The decay curves are well fitted with two simple exponential decay functions indicating the existence of two origins. Liquid nitrogen-temperature emission spectra show two emission peaks suggesting that they originate from Mn2+ ions on Td and on Oh sites. The emission intensity of Mn2+ ions on Td sites is drastically increased whereas that of Mn2+ ions on Oh sites is decreased. The variation of the optical characteristics agrees with the concentration of Mn2+ ions at Td site and its site environment.