Key Words:SiO2; LaPO4:Eu3+; Core-shell structure; Wet-chemical route; Luminescence
Abstract:SiO2@LaPO4:Eu3+ core-shell phosphors have been successfully synthesized by a one-step and economical wet-chemical route at low temperature. The as-obtained products were characterized by means of photoluminescence spectroscopy (PL), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The SEM, EDS and XPS analysis indicate that SiO2@LaPO4:Eu3+ core-shell phosphors can only be synthesized in a pH range of 8-11 and the possible mechanism has been proposed. The XRD results demonstrate that the structure of LaPO4:Eu3+ layers is transferred into monoclinic phase from hexagonal phase after annealing at 800 degrees C for 2 h. The SiO2@LaPO4:Eu3+ phosphors show strong orange-red luminescence under ultraviolet excitation. The relative emission intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles, and the optimum concentration for Eu3+ was determined to be 5 mol% of La3+ in SiO2@LaPO4 phosphors. (C) 2015 Elsevier Ltd. All rights reserved.
Volume:83
Translation or Not:no