Reddish-orange and neutral/warm white light emitting phosphors: Eu3+, Dy3+ and Dy3+/Eu3+ in potassium-zinc phosphate glasses

Abstract A multicolor luminescence investigation of potassium-zinc phosphate glasses activated with Eu 3+ , Dy 3+ and Dy 3+ /Eu 3+ is performed by analyzing their Raman and photoluminescence spectra, and decay times. Reddish-orange light emission, with a correlated color temperature ( CCT ) of 2117 K and a high color purity of 96.8%, is observed in the Eu 3+ singly-doped glass excited at 393 nm. Upon Dy 3+ excitation at 348 nm the Dy 3+ singly-doped glass emits neutral white light of 4396 K, and codoping with Eu 3+ the glass phosphor also emits neutral white light of 4017 K. In the codoped glass the neutral white light emission is generated mainly by the transitions 5 D 0 → 7 F 2 of Eu 3+ and 4 F 9/2 → 6 H 13/2 , 6 H 15/2 of Dy 3+ , Eu 3+ being sensitized by Dy 3+ through non-radiative energy transfer with an efficiency of 0.11. From an analysis of Dy 3+ emission decay time profiles it is inferred that an electric quadrupole-quadrupole interaction into Dy 3+ – Eu 3+ clusters might be the dominant mechanism in the Dy 3+ to Eu 3+ energy transfer. Upon Dy 3+ and Eu 3+ co-excitations at 362 and 381 nm, the Dy 3+ /Eu 3+ codoped glass can exhibit warm white and reddish-orange overall emissions, with CCT values of 3040 and 1735 K, respectively.