Photoluminescence, thermoluminescence and evaluation of some parameters of Dy3+ activated Sr5(PO4)3F phosphor synthesized by sol-gel method

Abstract

In this study, we have synthesized Dy3+ activated Sr5(PO4)3F (S-FAP) phosphors by sol-gel synthesis method. The synthesized phosphors were characterized by X-ray diffraction pattern (XRD), scanning electron microscopic (SEM), photoluminescence (PL) and thermoluminescence (TL) for structural, morphological and luminescent properties. Dy3+ activated Sr5(PO4)3F phosphor shows its characteristic PL emission at 481 nm and 574 nm due to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions, respectively. TL characteristics of Dy3+ doped Sr5(PO4)3F phosphors were taken after irradiation by 60Co gamma exposure. Two separate TL peaks at 126 °C and 279 °C were observed in case of Dy3+ doped phosphor. Sr5(PO4)3F:Dy3+ phosphor was irradiated within a wide range of exposure of 50 Gy to 7 kGy doses. Linearity was found up to 2 kGy and thereafter TL response saturates. Fading study was also carried out over the duration of six weeks for Sr5(PO4)3F phosphor. Trapping parameters were calculated using Chen's peak shape method, initial rise method and various heating rate method. Glow curve is deconvoluted using computerized glow curve deconvolution program. TL sensitivity of Sr5(PO4)3F:Dy3+ phosphor is found to be less by a factor of 2.08 than commercially used CaSO4:Dy phosphor. In order to identify the defect centers formed upon γ-ray irradiation in Sr5(PO4)3F:Dy3+ phosphor, EPR measurements were carried out on un-irradiated and irradiated phosphors.