LaPO4:Eu3+, LaPO4:Ce3+, and LaPO4:Ce3+,Tb3+ nanocrystals: Oleic acid assisted solvothermal synthesis, characterization, and luminescent properties

LaPO4:Ln(3+) (Ln = Eu, Ce, Tb) nanocrystals were successfully synthesized via a facile solvothermal process in the presence of oleic acid. The as-prepared crystals were well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), optical spectra as well as the kinetic decay times, respectively. In the synthesis process, oleic acid as a surfactant has played a crucial role in confining the growth and size of the LaPO4:Ln(3+) phosphors. All the samples are well crystallized and assigned to the monoclinic monazite-type structure of the LaPO4 phase. The prepared LaPO4:Ln(3+) phosphors present a narrow distribution with an average particle size of about 15 nm. Upon excitation by ultraviolet radiation, the LaPO4:Eu3+ phosphors show the characteristic D-5(0)-F-7(1-3) emission lines of Eu3+, while the LaPO4:Ce3+,Tb3+ exhibits the characteristic D-5(0)-E-7(3-6) emission lines of Tb3+. It is believed that these rare earth ion doped (Eu3+ ion or Ce3+ and Tb3+ ions co-doped) monoclinic monazite-type LaPO4 nanocrystals could find potential application as future advanced optical materials. (C) 2010 Elsevier B.V. All rights reserved.