Host Sensitized White Luminescence from ZnGa[sub 2]O[sub 4]:Dy[sup 3+] Phosphor

Dysprosium-doped zinc gallate phosphors with the nominal formulas ZnGa 2(1-x) O 4 :Dy 2x were prepared by the high-temperature conventional solid-state reaction technique, the dopant concentration being varied in the range 0 ≤ x ≤ 0.025. Zn 1-x Ga 2 O 4 :Dy x and Ga 2(1-x) O 3 :Dy 2x samples were also prepared for comparison for a dopant concentration of x = 0.02. Only the intrinsic self-activated emission of the ZnGa 2 O 4 host is observed in the photoluminescence emission spectra of Zn 0.98 Ga 2 O 4 :Dy 0.02, while both the host emission band and characteristic emission lines ( 4 F 9/2 → 6 H J ) of Dy 3+ are observed for ZnGa 2(1-x) O 4 :Dy 2x and Ga 1.98 O 3 :Dy 0.04 phosphors. The luminescent intensity differs in the phosphors due to the different energy-transfer rates from the respective hosts to the luminescent centers. Photoluminescent studies reveal the fact that Dy 3+ ions replace Ga 3+ ions in the host lattice at their octahedral sites. The source of white luminescence in the doped samples is the nonradiative resonant energy transfer via exchange interaction between the host and the activator. The CIE coordinates of the 2.5 atom % Dy 3+ -doped sample (0.32, 0.33) matches well with achromatic white (0.33, 0.33) on the chromaticity diagram.