Insights into the structure, photoluminescence and Judd-Ofelt analysis of red emitting SrLaLiTeO6: Eu3+ phosphors

Novel red-emitting phosphors, SrLaxEu1-xLiTeO6 (x = 0.025, 0.05, 0.075, 0.1, 0.125 and 0.15) have been synthesized via solid state ceramic route. The monoclinic symmetry (P2(1)/n) of the phosphors is confirmed from the Rietveld refinement of the XRD patterns. Raman spectrum of the SrLa0.9Eu0.1LiTeO6 phosphor shows slight blue shift of the phonon modes in low wavenumber region compared to host spectrum which confirms the substitution of Eu3+ ions in the A-site of the perovskite lattice. The band gap energies are found to decrease with Eu3+ substitution. The photoluminescence excitation spectra of SrLaLiTeO6: Eu3+ phosphor exhibit a charge transfer band centered at 293 nm and several narrow peaks due to the characteristic f-f transitions within Eu3+ ions. The dominant red emission at 614 nm also support the incorporation of Eu3+ ions within the A-site of the lattice without an inversion center, which is further confirmed by the Judd-Ofelt intensity parameter, Omega(2). The critical distance of energy transfer among Eu3+ ions is estimated to be 13.4 angstrom which implies electric multipolar interactions between the activator ions. Activation energy of the phosphor is estimated from temperature dependent photoluminescence spectra and is found to be 0.22 eV which indicates that the phosphor is thermally stable. (c) 2019 Elsevier B.V. All rights reserved.