Molten salt synthesis and luminescent properties of GdVO4:Eu3+ nanophosphors

GdVO4:Eu3+ nanophosphors were prepared via molten salt synthesis. Equal moles of NaNO3 and KNO3 were used as reaction medium, rare earth nitrates and NH4VO3 as precursors, and NaOH as alkalizer. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), photoluminescence (PL) spectrum and lifetime were used to characterize the nanophosphors. XRD demonstrates that NaOH concentration and the sintering temperature play important roles in the crystallinity and the phase purity of the products. The optimum NaOH concentration and sintering temperature are 2:40 and 400 °C, respectively. TEM micrographs show that the GdVO4:Eu3+ nanocrystals exhibit a cubic morphology and have a mean size of about 20 nm, which is in good agreement with that calculated by Scherrer's formula. Both the cell parameters and the volume of GdVO4:Eu3+ nanocrystals decrease due to the existence of big quantity of dangling bonds on the particle surface. Upon excitation at 315 nm, the GdVO4:Eu3+ nanocrystals show the strong characteristic emission of Eu3+, which indicates the efficient energy transfer from VO43- groups to Eu3+. The best doping concentration of Eu3+ in GdVO4 is determined to be 5 mol%. Copyright © 2014, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved