Warm white emission of LaSr2F7:Dy3+/Eu3+ NPs with excellent thermal stability for indoor illumination

The novel single Dy3+-activated and Dy3+/Eu3+ co-activated LaSr2F7 NPs-based phosphors were successfully synthesized via a simple precipitation reaction method at room temperature. The phase formations and cell parameters of single Dy3+-activated and Dy3+/Eu3+ co-activated LaSr2F7 NPs were verified in detail by the Rietveld refinement technique based on the recorded X-ray diffraction patterns. The doping concentration of single Dy3+-activated LaSr2F7 NPs was optimized to be 0.1 mol with the concentration quenching dominated by the electric dipole-dipole interaction. Meanwhile, a variety of Eu3+-activated La0.9Sr2F2:0.1Dy(3+) NPs exhibited tunable luminescent properties and emitted warm white light in close to standard warm white light under 363 nm excitation. The valid energy transfer (ET) efficiency from Dy3+ to Eu3+ ions was estimated to be about 86.02% based on the emission intensity while the electric dipole-quadrupole interaction dominated the concentration quenching mechanism in ET process. Eventually, the thermal quenching of the obtained samples was studied, showing the excellent thermal stability. All the results manifest that Eu3+-activated LaSr2F2:Dy3+ NPs could emit warm white light with excellent thermal stability for indoor illumination. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.