Synthesis of Red-Emitting MgSrB₂O₅:Eu³⁺ Phosphor for w-LEDs and Beta Radiation Dosimetry

Novel MgSrB₂O₅:Eu³⁺ nanophosphor was synthesized by a simple, low-cost solution combustion method using urea as fuel. X-ray diffraction confirmed the formation of the phosphor with an average particle size of 28.63 nm. The MgSrB₂O₅:1.5 mol% Eu³⁺ sample shows a band gap of 4.79 eV and a refractive index of 2.0325. SEM images show an agglomerated arrangement of particles. For photoluminescence (PL) characterization, excitation wavelengths at 393 and 464 nm, emission peaks were obtained at 594, 616, 654 and 701 nm. The maximum PL intensity was observed at 1.5 mol% Eu³⁺ concentration. At 1.5 mol% (616 nm) concentration, quenching occurs mainly due to dipole-dipole interactions. These emissions are attributed due to the ⁵D₀ → ⁷F_{j = 1.2,3,4} transition of Eu³⁺, which varies with temperature. The average fluorescence lifetime of the Eu³⁺-doped MgSrB₂O₅ phosphor (1.5 mol%) was 2.6459 ms. The thermoluminescence (TL) behaviour of Eu³⁺-activated MgSrB₂O₅ was examined across a range of beta irradiation doses from 3 to 10 Gy. The resulting sample exhibited improved thermal stability. The emission at 701 nm falls within the far-red absorption spectrum of phytochrome, making it potentially useful for white light-emitting diode fabrication and beta radiation dosimetry.