Dual-emitting Dy3+/Eu3+ co-doped SrLaGaO4 phosphor: Tunable luminescence, energy transfer and ratiometric temperature sensing

Abstract

Dy3+/Eu3+ co-doped SrLaGaO4 warm white phosphor was synthesized by solid state reaction and studied for the first time. Under 352 nm excitation, the obtained tetragonal SrLaGaO4: Dy3+ phosphor exhibit blue (483 nm) and yellow (577 nm) emission and the optimal doping concentration of Dy3+ is 5 mol%. After co-doping with Dy3+ and Eu3+ ions, phosphor emits warm white light and the correlated color temperature can be adjusted from 4745 K to 3004 K. The quantum yield of SrLaGaO4: 0.05Dy3+ and SrLaGaO4: 0.05Dy3+, 0.008Eu3+ are 11.3 % and 13.27 %, respectively. In addition, temperature-dependent spectra showed that Dy3+ and Eu3+ have different emission variations in SrLaGaO4: 0.05Dy3+, 0.012Eu3+ phosphor, which was explained by thermally induced energy transfer between Dy3+ and Eu3+ in configuration coordinate diagram. The fluorescence intensity ratios of Eu3+ and Dy3+ at 298 K- 423 K were calculated to analyze the temperature sensing properties. The maximum absolute sensitivity of SrLaGaO4: 0.05Dy3+, 0.012Eu3+ phosphor was obtained as 0.63 % K–1 at 298 K. Finally, the WLED device is prepared by SrLaGaO4: Dy3+, Eu3+ phosphor, which emits warm white light with a correlated color temperature of 3550 K. In summary, SrLaGaO4: Dy3+, Eu3+ are excellent single-phase warm white component applicated for WLED and optical thermometers.