Investigation of photoluminescence and thermoluminescence properties of UV& γ irradiated Li₄SrCa(SiO₄)₂:Dy³⁺ phosphor

A series of Dy³⁺-activated Li₄SrCa(SiO₄)₂ phosphors were synthesized using a high-temperature solid-state reaction method. The crystal structure, surface morphology, elemental analysis and vibrational modes of synthesized phosphor were studied using X-ray Diffraction, Scanning electron microscope, Energy dispersive X-ray spectroscopy and Raman Spectroscopy technique, respectively. Luminescence properties of Li₄SrCa(SiO₄)₂:Dy³⁺ phosphors were analyzed by photoluminescence (PL) and thermoluminescence (TL) techniques. Photoluminescence spectra of Dy³⁺ doped Li₄SrCa(SiO₄)₂ phosphors were efficiently excited in the range of 300–400 nm and exhibited two emission peaks, positioned at 481 nm (blue) and 575 (yellow) due to ⁴F_9/2–⁶H_15/2 and ⁴F_9/2– ⁶H_13/2 transitions, respectively, under excitation wavelength of 348 nm. CIE colour coordinate (x = 0.2983, y = 0.3151), Colour purity (13.3%), and CCT (7550 K) of the material were calculated which indicated that the prepared phosphor can be used as a white light-emitting phosphor. The TL glow curves of the synthesized phosphor were recorded using a Nucleonix 1009I TLD reader. All synthesized Li₄SrCa(SiO₄)₂:4mol%Dy³⁺ phosphors were exposed to UV rays (254 nm) and γ-rays (⁶⁰Co source). Maximum TL intensity was found for 40 min under UV irradiation (254 nm), and for γ irradiation (dose rate 8 kGy). Trapping parameters like activation energy, frequency factor and order of kinetics were calculated by Chen’s peak shape method. The activation energy vs. T_stop method verifies the existence of overlapping peaks. In this work the long-lasting glow characteristics of prepared samples using fading measurements, and along with the TL emission spectrum were also investigated. Overall Li₄SrCa(SiO₄)₂:Dy³⁺ phosphor revealed that the prepared phosphor can be used for excellent WLED phosphor and TLD material for both UV & γ based TL dosimetric applications.