Visible spectroscopic properties of SiO2–Na2O–Al2O3–LaF3 glass ceramics doped with Dy3+ and Ho3+ under blue LED excitation

Abstract SiO 2 –Na 2 O–Al 2 O 3 –LaF 3 glasses were doped with various rare earth ions to find the proper active ions for blue LED (λ = 455 nm) color conversion. Based on photo-luminescence (PL) spectra, a combination of Dy 3+ and Ho 3+ was selected and their visible spectroscopic properties were investigated for possible candidate of white color conversion of a blue LED. Concentrations of Dy 3+ and Ho 3+ were varied to find the proper combination, and 2 mol% DyF 3 and 1 mol% HoF 3 co-doped glass showed reasonable visible emissions. When the glasses were heat treated, emission intensities from both ions were clearly increased by the formation of LaF 3 nano-crystals, which were identified by X-ray diffraction and TEM analyses. Emission peak at ~ 525 nm newly appeared due to nano-crystal formation and the related local phonon energy change nearby Dy 3 + ion. Energy transfer between Dy 3 + and Ho 3 + was also observed and discussed. Photo-luminescence excitation (PLE) spectra were measured and also discussed.