The novel single Dy3+-activated and Dy3+/Eu3+ co-activated LaSr2F7 NPs-based phosphors were success-fully 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 La0.9Sr2F7∶0.1 Dy3+ 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 LaSr2F7∶Dy3+ NPs could emit warm white light with excellent thermal stability for indoor illumination.