Dual-function luminescence of Ce³⁺- and Dy³⁺-doped Ba₂Al₂SiO₇ phosphors for solid-state lighting and optical thermometry: A comparative study

This study aims to compare dual luminescence characteristics of Ba₂Al₂SiO₇ phosphors doped with Ce³⁺ and Dy³⁺ synthesised via a urea-assisted combustion process. X-ray diffraction (XRD) was employed to verify the unaltered polycrystalline structure following doping. Fourier-transform infrared (FTIR) spectroscopy showed that the host structure remains unchanged after doping. Scanning electron microscopy (SEM) showed that the particles were highly agglomerated and were unevenly shaped. The two dopants showed different emission profiles in photoluminescence (PL) measurements: Ce³⁺-activated phosphors showed broad blue emission from 5d→4f transitions following spin-orbit coupling, whereas Dy³⁺-doped samples showed distinctive blue, yellow and weak red emissions from ⁴F_9/2 → ⁶H_13/2 and ⁴F_9/2 → ⁶H_15/2 and ⁴F_9/2 → ⁶H_11/2, respectively. Significant differences in the thermal quenching behaviour were observed in temperature-dependent luminescence studies. Samples doped with Dy³⁺ only lost about 12% of their emission intensity as the temperature rose from 303 to 483 K, while phosphors doped with Ce³⁺ showed a more noticeable decrease of about 31% under the same circumstances. Optical thermometry applications are well suited for Dy³-doped phosphors due to their greater activation energy and quenching temperature (T_Q). The comparison study suggests that Ce³⁺-doped Ba₂Al₂SiO₇ may be a suitable blue-emitting phosphor for solid-state illumination. In comparison, Dy³⁺ doping provides dual functionality with improved temperature-dependent luminous performance. These results show that the development of multifunctional materials suitable for lighting and thermal sensing technologies is made possible by careful dopant selection in barium aluminosilicate matrices.