Structural and photoluminescence properties of UV-excited Er3+ doped Ba2CaWO6 yellowish-green phosphors

Abstract

Double perovskite Ba2CaWO6 phosphors doped with different concentrations of Er3+ have been synthesized by the conventional solid state reaction method in air at 1250 °C and are characterized by X-ray diffraction analysis (XRD), Energy Dispersive X-ray Spectrometer (EDS), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and Photoluminescence measurements. An intense green and weak red emissions are observed at 566 nm (4S3/2 → 4I15/2), 680 nm (4F9/2 → 4I15/2) under 314 nm, 378 nm corresponding to charge transfer band and rare earth excitations respectively. Under charge transfer excitation Ba2CaWO6:xEr3+ samples exhibit high intense emission peaks of Er3+ than the rare earth excitation. This is due to an efficient energy transfer from WO66- to Er3+. The maximum emission intensity was observed for 0.08 wt% concentration of Er3+ ions in Ba2CaWO6 phosphors. The critical energy transfer distance among Er3+ ions is calculated to be 15.18 Å and the quenching mechanism is due to dipole-dipole interaction. The energy transfer mechanism is discussed based on the energy level diagram of Er3+. The radiative lifetimes were determined from the fluorescence decay analysis. The CIE color coordinates were calculated from the emission spectra. The result shows that Ba2CaWO6: Er3+ phosphor can be considered as a potential candidate for UV excited yellowish-green phosphor for display applications.