Visible-light emission properties of α-TeO2:Ho3+/Yb3+/Eu3+ nanoparticles via both up-and down-conversion modes

In this study,α-TeO:Ho/Yb,α-TeO:Euand α-TeO:Ho/Yb/Eunanoparticles were prepared via a simple hydrothermal process.The up- and down-conversion properties of the as-prepared nanoparticles were tested at room temperature under a near-infrared photo source(980 nm) and UV-vis photo source,respectively.The results indicated that α-TeONPs were a kind of outstanding host material for both up- and down-conversion luminescence.The α-TeO:Ho/Ybnanoparticles showed sharp up-conversion emission at 545 and 660 nm under 980 nm excitation,ascribed to the ~5S→~5Iand ~5F→~5I(Ho) transitions,and weaker down-conversion emission at 545 nm under 455 nm excitation,ascribed to the ~5S→~5I(Ro) transitions.The α-TeO:Eunanoparticles showed strong down-conversion emission at 592 and 615 nm under 395 nm excitation,attributed to the ~5D→~7Fand~5D→~7F(Eu) transitions.Possessing the advantages of these two luminescent materials,the as-prepared tri-doped samples ofα-TeO:0.5Ho/10Yb/3Eu(mol.%) nanoparticles could successfully emit visible light via both up- and down-conversion modes.