Synthesis and luminescence characterization of Eu3+ -doped Ca7 Mg2 (PO4 )6 phosphor for eco-friendly white light-emitting diodes and thermoluminescence dosimetric applications

Abstract

A Eu³⁺ -activated Ca₇ Mg₂ (PO₄ )₆ phosphor was prepared at high temperature (800°C) using a solid-state reaction method. The crystal structure, phase formation of the prepared phosphor was characterized using X-ray diffraction patterns and Fourier transformed infrared analysis. The luminescence properties of the synthesized phosphor were characterized using photoluminescence and thermoluminescence techniques. The prepared phosphor showed two emission peaks at 594 nm with an orange colour due to the ⁵ D₀ →⁷ F₁ transition and at 612 nm a red colour due to the ⁵ D₀ →⁷ F₂ transition under 396 nm near-UV excitation. The prepared phosphors were irradiated with different doses of γ-rays from a ⁶⁰ Co gamma irradiation source. Thermoluminescence glow curves for this sample phosphor were obtained using a Nucleonix 1009I TL reader. Synthesized phosphor samples were exposed to a 3.6 kGy dose of γ-rays. The thermoluminescence glow curve of the Ca₇ Mg₂ (PO₄ )₆ :0.05 mol%Eu³⁺ phosphor showed maximum intensity at all concentrations of Eu³⁺ ions. The Ca₇ Mg₂ (PO₄ )₆ :0.05 mol%Eu³⁺ phosphor was irradiated with different doses of ⁶⁰ Co γ-irradiation and a linear response was observed between 0.6 kGy and 3.6 kGy. Trapping parameters such as activation energy, frequency factor and order of kinetics were calculated. The CIE chromaticity diagram showed the colour coordinates of the synthesized phosphor in the orange and red regions of the visible spectrum; this spectral feature revealed high colour purity and excellent chromaticity coordinate characteristics. Photoluminescence and thermoluminescence properties revealed that the prepared phosphor could be a potential red-emitting phosphor for eco-friendly white light generation and an excellent thermoluminescent dosimeter material for thermoluminescence dosimetric applications.

Keywords: photoluminescence; solid-state reaction method; thermoluminescence; trapping parameter.