Molten Salt Synthesis and Luminescent Properties of YNbO4: Eu Nanophosphors

YNbO4:Eu nano-phosphors were successfully prepared in NaNO3 molten salt. X-ray diffraction was used to characterize the structure of the samples. The results indicate that a suitable amount of NaOH in NaNO3 molten salt can effectively improve the crystallinity of the samples annealed at same temperature; meanwhile, the elevation of annealing temperature increases the crystallinity, and transfers the crystalline phase from scheelite to fergusonite. The micrographs of transmission electron microscopy reveal that the grain size increases with the elevation of annealing temperature. Upon excitation into the niobate groups at 260 nm, YNbO4:Eu nano-phosphors exhibit weak emission at 405 nm, originated from Nb–O charge transfer transition and the characteristic emission of Eu3+, which indicates there is an energy transfer from niobate group to Eu3+. Monitored by emission of 615 nm, the excitation spectrum shows that the f-f transition of 7F0–5L6 at 396 nm is more intense than the Nb–O charge transfer band at 260 nm. This intense absorption at 396 nm make YNbO4:Eu nano-phosphors an excellent candidate of white light emitting diode.