Ce3+ and Ln3+ (Ln = Dy, Eu, Sm, Tb) Codoped SrF2 Nanoparticles: Synthesis and Multicolor Light Emission

For optically active Ln3+ ions, fluoride is a very good luminescent substrate that has been used in the field of lasers, solid-phase optical transmitters, optical communications, up/down conversion. This work reports a systematic study on bridging between structure and tunable luminescence for SrF2:Ce3+/Ln3+ (Ln = Dy, Eu, Sm, Tb) nanoparticles. Regardless of the dopant level, all nano-crystals crystallized in a single cubic phase with the diameter of ~20-30 nm. It was found that SrF2:Ce3+ exhibited intense ultraviolet emission under 288 nm excitation which can be attributed to the typical 4f-5d transition of Ce3+ ions. After the incorporation of Ln3+ ions, multicolor emission can be achieved when excited by the 4f-5d transition of Ce3+. This result gave an evidence that the excitation energy of Ce3+ can be transferred to Ln3+ leading to multicolor emission. The findings reported in this work may provide useful information in designing novel luminescent materials for tailored performances.