Thermoluminescent dosimetry properties of calcium oxide obtained from eggshells

In response to the growing demand for sustainable and cost-effective dosimetric materials, this study explores the synthesis and thermoluminescence (TL) characteristics of calcium oxide (CaO) particles obtained from chicken eggshell biowaste. CaO was prepared through a green calcination route at 1000 °C and its structural and morphological properties were confirmed via XRD, SEM, EDX, and elemental mapping, indicating high-purity nanocrystalline CaO with uniform elemental distribution. The TL response of the synthesized CaO was evaluated under gamma irradiation with systematic optimization of annealing conditions. TL glow curve exhibited two broad glow peaks centered at about 145 and 273 °C. Samples annealed at 500 °C for 20 min exhibited the highest TL sensitivity. Three component glow peaks were identified in the complex glow curve of the synthesized sample. Among these, the high temperature peak centered at 273 °C with the activation energy of 1.13 eV was revealed as the most relevant for dosimetric applications due to its thermal stability and strong TL emission. The synthesized CaO showed a broad linear dose-response ranging from 5 to 500 Gy with excellent correlation (R² ≈ 0.99), minimal fading of ∼8 % over 35 days for the high-temperature peak and stability over multiple annealing, irradiation and readout cycles. These findings underscore the potential of eggshell-derived CaO as a low-cost, eco-friendly, and reliable TL dosimeter for high-dose radiation monitoring.