Swift heavy ion induced structural, optical and luminescence modification in NaSrBO₃:Dy³⁺ phosphor

The effect of 120 MeVAg⁹⁺ ion irradiation on the structural, optical and luminescence properties of NaSr_1-xBO₃:xDy ³⁺ (x = 0.5-2.5 mol%) phosphor synthesized by the conventional solid state reaction route is reported. The samples were irradiated with Ag ⁹⁺ swift heavy ions (SHIs) using fluences of 1 × 10 ¹², 5 × 10¹² and 1 × 10¹³ ions cm^-2. The unirradiated as well as irradiated samples were characterized by powder X-ray diffraction (PXRD), diffuse reflectance (DR) and photoluminescence techniques. PXRD confirms no change in the phase after irradiation except that loss of crystallinity had been observed which may be due to the fragmentation caused by the SHI. A blue shift in the absorption band of the DR was observed, resulting in an increase in the band gap from 5.61 eV to 5.77 eV, after ion irradiation. An increase in photoluminescence intensity (excited at 385 nm) was observed with increased ion fluences. The ratio of the blue to yellow emission peaks (I₄₈₃/I₅₇₇) was calculated and found to be varying with ion fluences suggesting that the white light can be achieved by tailoring this yellow to blue ratio. The Commission Internationale de l'Eclairage coordinates were calculated and found to move toward the white region after irradiation.