Study of luminescence characteristics of K2Ca2(SO4)3:Eu microphosphor by electron and gamma irradiation

Microcrystalline K2Ca2(SO4)3:Eu sample was prepared by the solid-state diffusion method using the precursors K2SO4 and CaSO4 in the molar ratio 1:2. The required quantity of the impurity (0.1 mol %) was doped in the form of EuCl2. The synthesized sample was crushed and sieved to get samples in the particle size range of 100–200 µm. The powder sample was then annealed at 700 °C for 2 h. The samples were made in the form of pellets. These pellets were irradiated with 6 MeV electrons at different fluences, varying from 2.5×1011 to 5×1013e/cm2. The samples were characterized by XRD technique and Thermoluminescence (TL) and Photoluminescence (PL) were studied. Photoluminescence studies of the K2Ca2(SO4)3:Eu microphosphor shows a single excitation band at 322 nm and emission at 425 nm, which could be assigned to Eu2+ emission. 6 MeV electron irradiated K2Ca2(SO4)3:Eu microphosphor shows increase in the PL emission intensity upto an electron fluence of 1×1012 e/cm2 and then decreases with further increase in the fluence. The thermoluminescence property of the synthesized phosphor was studied for 6 MeV electrons as well as 60Co gamma radiations. The thermoluminescence glow curves of K2Ca2(SO4)3:Eu microphosphor exposed to different electron fluences show a single glow peak at around 154 °C along with small hump at around 105 °C. Also, when irradiated with 60Co gamma radiations, it shows single glow peak at 152 °C and small hump at around 108 °C. The TL response curve of K2Ca2(SO4)3:Eu phosphor irradiated with electrons found to be linear in a fluence range from 2.5×1011 to 1×1012 e/cm2 and after which it shows a sub-linear behavior and that of irradiated with gamma dose shows linearity over 1 Gy to 500 Gy after which it starts saturating.