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.