Correlation between ion induced defects and luminescence properties of K3Na(SO4)2: Eu nanophosphor

The K3Na(SO4)2: Eu phosphor has been prepared by chemical co-precipitation method. X-ray diffraction studies show that K3Na(SO4)2: Eu phosphor exhibits hexagonal structure with average particle size of 42 nm. The samples were irradiated with 1.2 MeV Argon ions, with fluences varying between 1011 and 1015 ions/cm2. Monte Carlo SRIM-2008 Simulation was used for evaluating ion range, ion energy loss and ion induced atomic displacements. Ions having a range of 2.09 μm lose their energy mainly via electronic stopping, by creating large number of defects and activating different trap centers. This results in composite thermoluminescence (TL) glow curves. The growth of lower temperature peak at around 449 K which was linear in the whole studied dose range, might be attributed to the change in trap centers and luminescence centers populations. The observed variation in TL intensity of the higher temperature peak at 533 K is the resultant effect of both increases in density of ion beam tracks and high ionization density. A photoluminescence (PL) emission peak is seen around 415 nm when excited by 310 nm light, due to transition from an excited state of 4f65d configuration to 8S7/2 state of Eu2+ ion. The higher concentration of defects that generate nonradiative states within the band gap is responsible for decrease in PL intensity after irradiation. The composite TL glow peaks were first deconvoluted with GlowFit program and then kinetics parameters of isolated prominent peaks were calculated by the thermoluminescence peak shape and various heating rate methods.