Up-conversion emission in violet from neodymium oxalate and neodymium oxide phosphors obtained by microemulsion technique

This paper presents an up-conversion emission in violet (404 nm) color from neodymium oxide and neodymium oxalate nanoparticles upon excitation with a yellow light (580 nm). Powder phosphors of neodymium oxide and neodymium oxalate nanoparticles were synthesized by the microemulsion technique. In addition to this violet emission, two UV emissions at 342 and 370 nm, and a weak blue emission at 450 nm have been observed and these are assigned to electronic transitions appropriately. The lifetimes of the violet color emission transition at 404 nm have been obtained; the mechanism of the up-conversion emission has been explained. The oxide-based phosphor has shown strong up-conversion emission compared to the oxalate-based phosphor. The transmission electron microscopy (TEM) measurement shows that the oxide phosphor is in nanocrystal structure.