Influence of fuel type on the structural and optical properties of Dy3⁺ activated Ba₂MgSi₂O₇ phosphors

Abstract This paper presents a comparative study of dysprosium-doped di-barium magnesium disilicate (Ba 2 MgSi 2 O 7 : Dy 3+ ) phosphors. We synthesized these materials using a combustion method, employing two distinct fuels as reducing and stabilizing agents: aloe vera (a biofuel) and urea (an organic fuel). Our investigation involved a comprehensive characterization of these phosphors. We used Powder X-ray Diffraction (PXRD) to confirm the formation of monoclinic phases in both aloe vera and urea-prepared Ba2​MgSi2​O7​: Dy 3+ nanoparticles (NPs). Scanning Electron Microscopy (SEM) provided insights into their morphology, while Fourier Transform Infrared (FTIR) spectroscopy helped analyze their chemical bonds. Crucially, we examined their luminescence properties. The thermoluminescence (TL) and photoluminescence (PL) behavior were studied after exposure to gamma rays. Our findings indicate that aloe vera proved to be the more effective "green" fuel, yielding higher quality Ba 2 MgSi 2 O 7 : Dy 3+ ​ NPs. Optical absorption studies revealed that the bandgap of these Ba 2 MgSi 2 O 7 : Dy 3+ NPs is significantly influenced by the synthesis method and the type of fuel used. Interestingly, the highest bandgap of 4.40 eV was observed for NPs fabricated with urea, while the lowest, 4.20 eV, was found for those prepared with aloe vera. Further Photoluminescence (PL) and Electron Spin Resonance (ESR) analyses confirmed the presence of Schottky and Frenkel surface defects, along with self-trapped excitons and oxygen vacancies, within these Ba 2 MgSi 2 O 7 : Dy 3+ NPs. The TL glow curves of Ba 2 MgSi 2 O 7 : Dy 3+ phosphors (with 1–4 mol% doping) showed distinct thermally activated trap centers depending on the fuel. Urea-based phosphors exhibited a TL glow curve with two peaks at 368.29 K and 563.93 K, whereas samples prepared with aloe vera gel displayed more intense peaks at a higher temperature of 375.35 K and 572.16 K. This suggests that aloe vera-derived phosphors possess enhanced trap depths and greater TL sensitivity. Finally, the phosphors demonstrated low fading behavior, a critical characteristic that confirms their promising suitability for various dosimetric applications. Graphical abstract