Thermoluminescence characteristics of CaO particles under X-ray irradiation

Abstract

Calcium oxide obtained from waste chicken eggshells was prepared through high-temperature calcination and its thermoluminescence characteristics under X-ray irradiation were systematically examined. X-ray diffraction analysis confirmed the successful formation of phase-pure cubic CaO with an average crystallite size of approximately 39 nm. Scanning electron microscopy revealed irregular and agglomerated particles with rough and porous surface features. The TL glow curves showed a pronounced dependence on annealing temperature, and the maximum TL intensity was achieved for samples annealed at 500 ◦C. Analysis based on the Tm–Tstop method combined with glow curve deconvolution indicated the presence of multiple trapping levels, including both shallow and deep traps with activation energies ranging from 0.91 to 1.32 eV. These trapping centers contribute to the material’s high sensitivity as well as its long-term signal stability. Additionally, activation energies were determined using the Initial Rise Method based on the Ln(I) vs 1/T and E vs Tstop plots, revealing the temperature dependence of trapping centers in CaO. The TL dose–response exhibited approximately linear behavior up to ~2 Gy, with a slope of 0.98 on a log–log scale, followed by a slight sublinear deviation at higher doses. Fading measurements demonstrated that a considerable fraction of the TL signal was preserved after 35 days of storage, and reusability tests confirmed stable TL performance over repeated irradiation–readout cycles. Overall, the results suggest that eggshell-derived CaO represents a low-cost and environmentally friendly TL material with potential for low-dose X-ray dosimetry applications.