Sr3Gd(PO4)3: Dy3+ phosphors for lighting applications

Sr3Gd(PO4)(3) phosphors activated with different concentrations of Dy3+ ions were prepared at 1250 degrees C/5 h by modified citrate sol-gel combustion technique and examined for lighting applications. The crystalline phase analysis was studied using powder X-ray diffraction and HR-TEM studies. The effect of Dy3+ concentration on morphology was studied through SEM and TEM. Optical band gap energy was estimated using diffused reflectance spectrum. The excitation, emission, luminescence decay and photometric characteristics were studied. The concentration of Dy3+ was optimized for strong and efficient emission through F-4(9/2) -> H-6(15/2), H-6(13/2), H-6(11/2) transitions. The photometric analysis was done by evaluating the CIE chromaticity coordinates and they were found to be (0.314, 0.360). The generation of white light and transfer of energy among the excited Dy3+ ions were discussed. It was observed that the transfer of energy takes places through dipole-dipole interaction among the excited Dy3+ ions at higher concentrations. The experimental findings show that the 1.0 mol% of Dy3+-doped Sr3Gd(PO4)(3) phosphor has greater potentiality to be used for lighting devices working at 352 nm UV excitation.