Abstract
Effective green long persistent phosphors (LPP) Sr4Al14O25:Eu2+ and Sr4Al14O25:Eu2+, RE3+ (RE = Nd, Dy) were prepared using solution combustion procedure at 600 °C and reheated for two hours at 1150 and six hours at 1350 °C in tube furnace in the reducing environment (in presence of 95 % N2 and 5 % H2). The effect of codopants (Nd3+ and Dy3+) on the luminescent and structural characteristics of materials were studied using photoluminescence (PL) spectroscopy, powder X-ray diffraction (PXRD), Fourier transformation infrared (FTIR) and transmission electron microscopy (TEM). The influence of concentration of dopant ions on the PL intensity was examined by varying Eu2+ concentration (0.01-0.05 mol) in host matrix. The incorporation of 0.03 mol Eu2+ ion in Sr4Al14O25 lattice produces maximum PL intensity. On 363 nm excitation, strong broad emission band is observed at 480−520 nm corresponding to 4f65d1→4f7 transition of divalent europium ions. The persistency and luminescence intensity is found to improve by doping Nd3+ and Dy3+ ions as codopants and also with increasing the temperature. PXRD study confirms the formation of single phase orthorhombic crystal symmetry with Pmma space group. The crystallinity of the materials increases with temperature. FTIR spectra determine the stretching and bending modes of vibrations to confirm the formation of metal-oxygen bonds. TEM images demonstrate the synthesis of nearly spherical shaped nanoparticles.
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