Luminescence and structural insights of β-Ca2SiO4:Pr3+ Phosphor: Applications towards TL dosimetry and solid state lighting

Abstract

Trivalent praseodymium (Pr³⁺) doped β-Ca₂SiO₄ (β-CSO:Pr³⁺) phosphors are successfully synthesized via the conventional solid-state reaction method. This sustainable approach utilized SiO₂ extracted from sugarcane bagasse and CaO derived from eggshells (ES). The thermoluminescence (TL) properties of un-doped and β-CSO:Pr³⁺ phosphors are evaluated under γ-irradiation doses ranging from 0.01 Gy to 5 kGy. The TL glow curves of β-CSO:3Pr³⁺ phosphors exhibited prominent peaks at 400 K and 550 K. Activation energy values, determined using CGCD and Chen's peak methods, ranged from 0.5 to 2.5 eV. The incorporation of Pr³⁺ ions introduced deeper traps and significantly enhanced the material's thermal stability. TL reusability measurements showed a standard deviation of less than 5 %, demonstrating consistent and reliable performance over multiple cycles. Deconvolution of the TL glow curves identified six distinct peaks in the un-doped sample, while the Pr³⁺ doped sample displayed a more intricate trap structure with four peaks, indicating the introduction of new or modified trapping sites due to Pr³⁺ doping. The Figure of Merit (FOM) values derived from the deconvolution analysis are all below 1.58 %, signifying an excellent fit between the observed and modelled TL signals. These findings establish β-CSO:3Pr³⁺ phosphors as robust candidates for radiation dosimetry, offering enhanced sensitivity, stability, and adaptability across various dosimetric applications. The excitation spectrum included a host-related excitation band (200–300 nm) and f-f transition bands of Pr³⁺ (440–500 nm), both of which align with commercially available blue-emitting LED chips. Upon excitation with UV (∼247 nm) and blue light (∼457 nm), the phosphors emitted red light primarily from the ³P₀ state of Pr³⁺ ions, with the dominant transition being ³P₀→³F₂ (∼653 nm). The optimal concentration of Pr³⁺ is determined to be 3 mol%, beyond which concentration quenching occurred due to d-d interactions. Furthermore, the β-CSO:3Pr³⁺ phosphors exhibited a color purity of 88.1 %, an internal quantum efficiency (I_QE) of 92.51 %, a high color rendering index (CRI) of 91, and a correlated color temperature (CCT) of 5162 K. These results highlight the promising potential of the synthesized nanorods for use in TL dosimetry and solid-state lighting applications.