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 Eu3+, Dy3+ and Dy3+/Eu3+ is performed by analyzing their Raman and photoluminescence spectra, and decay times. Reddish-orange light emission, with a correlated color temperature (CCT) of 2117K and a high color purity of 96.8%, is observed in the Eu3+ singly-doped glass excited at 393nm. Upon Dy3+ excitation at 348nm the Dy3+ singly-doped glass emits neutral white light of 4396K, and codoping with Eu3+ the glass phosphor also emits neutral white light of 4017K. In the codoped glass the neutral white light emission is generated mainly by the transitions 5D0→7F2 of Eu3+ and 4F9/2→6H13/2, 6H15/2 of Dy3+, Eu3+ being sensitized by Dy3+ through non-radiative energy transfer with an efficiency of 0.11. From an analysis of Dy3+ emission decay time profiles it is inferred that an electric quadrupole-quadrupole interaction into Dy3+ – Eu3+ clusters might be the dominant mechanism in the Dy3+ to Eu3+ energy transfer. Upon Dy3+ and Eu3+ co-excitations at 362 and 381nm, the Dy3+/Eu3+ codoped glass can exhibit warm white and reddish-orange overall emissions, with CCT values of 3040 and 1735K, respectively.