Exploring γ and UV irradiation responses on thermoluminescence and optical thermometry studies on Y4Al2O9:Ho3+ nanophosphor

Abstract

A series of green emitting Ho3+ (1–9 mol%) doped Y4Al2O9 nanophosphors (NPs) are synthesized via solution combustion technique. Photoluminescence (PL) studies shows emission peaks recorded at ∼ 522 nm (5F3→5I8), 545 (5F4, 5S2→5I8), 659 (5F5→5I8) and 730 (5F4→5I7) upon excited at 460 nm wavelength. With a tremendous potential for application in white light-emitting diodes (w-LEDs), the phosphors show a bright green emission under 460 nm excitation. They also have a notable activation energy (0.31 eV), high color purity (98.2 %), and a remarkable quantum yield (87.1 %). Most astonishingly, even at temperatures as high as 420 K, YAO:5Ho3+nanoparticles retain 88.9 % of their initial fluorescence intensity. Using the fluorescence intensity ratio (FIR) method, the temperature sensing potential is also investigated. Thermoluminescence (TL) glow curves of γ (1 kGy) and UV (1 h) irradiated YAO:Ho3+(1–9 mol%) NPs exhibit two glow curves and highest intensity is recorded for YAO:5Ho3+NPs. TL characteristics of 5 mol% Ho3+ doped YAO NPs are subjected to γ (1 Gy-5 kGy) and UV (0.25–6 h) irradiation. Two glow curves recorded at 475 K (major peak) and 567 K (shouldered peak) for γ irradiation. However, for UV irradiation two glow curves at 478 K (major peak) and 575 K (shouldered peak) are recorded utilizing a 5 °C per minute heating rate. TL intensity varies with γ and UV exposure is recorded for optimized NPs and major glow peaks showcase linear response for both γ and UV irradiations, indicating that the prepared phosphor can be used in TL personal dosimetry. Furthermore, compared to γ-irradiated phosphor, UV-irradiated phosphor shows greater fading. The overall results clearly demonstrate that the optimized phosphor has proven to be an outstanding candidate for multifunctional applications.