Up-conversion luminescence of neodymium oxalate nanoparticles/TiO2/organically modified silane composite thin films derived at low temperature

Abstract Neodymium oxalate nanoparticles/TiO2/organically modified silane (ormosil) composite thin films for photonic applications were prepared by a chemical approach combining the inverse microemulsion technique and the sol–gel method at low temperature. Transmission electron microscopy observation shows that the size of the neodymium oxalate nanoparticles is in the range from 10 to 40 nm. A relatively strong room-temperature violet up-conversion emission at 399 nm ( 4 D 3/2 → 4 I 13/2 ) has been measured from the composite thin films baked at different heat treatment temperature upon excitation with a yellow light at 587 nm. In addition to this violet emission, an UV emission at 376 nm and a blue emission at 467 nm have been obtained. The lifetimes of the violet emission have been measured and the mechanism of the up-conversion emission has been explained by means of an energy level diagram.