Elucidating structural, optical, and fluorescence intensity ratio-based temperature-sensitive luminescence aspects of Pr³⁺-activated Ca₂Al₂SiO₇ phosphors

In this study, we investigated the structural, optical, concentration, and temperature-sensitive luminescence properties of praseodymium (Pr³⁺)-doped Ca₂Al₂SiO₇ phosphors synthesised via a urea-assisted combustion method. Rietveld refinement and XRD analyses confirmed the formation of a tetragonal phase with a P͞42₁m space group. The energy band gap was 4.430 ± 0.124 eV, and DRS analysis confirmed different transitions of Pr³⁺ ions. The concentration dependency of the emission was explored using room-temperature PL, where the optimum performance was observed for a dopant concentration of 4 mol%. The UVC emission of Pr³⁺ ions is associated with the 4f¹5d¹ → ³H_J and ³F₂ energy levels, and the decay lifetime is in the range of 7.3–8 μs. The emission intensity decreased with increasing temperature, indicating temperature quenching. A high quenching temperature (412 K) and a high activation energy of 0.258 ± 0.016 eV were obtained for the CASO-4 Pr phosphor, confirming its exceptional thermal stability. The applicability in the field of temperature sensing was explored based on the FIR approach, estimating S_A as 2.562 × 10^–4 K⁻¹ and S_R as 0.02% K⁻¹ at 473 K.