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 o xalate nanoparticles were synthesized by the microemulsion technique. In ad dition to this violet emission, two UV emissions at 342 and 370 nm, and a w eak blue emission at 450 nm have been observed and these are assigned to el ectronic transitions appropriately. The lifetimes of the violet color emiss ion transition at 404 nm have been obtained; the mechanism of the up-conver sion emission has been explained. The oxide-based phosphor has shown strong up-conversion emission compared to the oxalate-based phosphor. The transmi ssion electron microscopy (TEM) measurement shows that the oxide phosphor i s in nanocrystal structure. (C) 2001 Elsevier Science B.V. All rights reser ved.