Synthesis and luminescence properties of novel red-emitting Na2ZnSiO4:Eu3+ phosphor with intense 5D0 → 7F4 transition and high quantum yield

Abstract

Novel red-emitting Eu3+-doped Na2ZnSiO4 phosphors were synthesized by a conventional high temperature solid reaction. The crystal structure was confirmed by X-ray diffraction (XRD) and the morphology was examined by scanning electron microscopy (SEM). The luminescence properties of Na2-xZn1-xSiO4:xEu3+ (NZS:xEu) phosphors were investigated by photoluminescence excitation (PLE), emission (PL) spectra and decay curves. The phosphors exhibit abnormal intense red emission which located at 702 nm due to the 5D0→7F4 transition of Eu3+ under the excitation of 393 nm and it makes the CIE chromaticity coordinates of the phosphors to fall in a red region. This phenomenon may be explained by the highly polarizable chemical circumstance. The optimum Eu3+ doping concentration of NZS:xEu is determined to be x = 0.08. The critical distance between Eu3+ was calculated to be 13.36 Å. The concentration quenching mechanism can be interpreted by the quadrupole–quadrupole interaction of Eu3+ ions. The decay curves show double exponential behavior for all concentrations of Eu3+ ions and the lifetimes varied from 0.67 to 1.3 ms when the Eu3+ doping concentration increased in the range of 4–12 mol%. The quantum yield (QY) of Na2ZnSiO4:0.08Eu3+ phosphor is calculated to be as high as 88.76%. The present work suggests that Na2ZnSiO4:Eu3+ phosphor is a promising candidate as a red component for NUV LEDs application.