Studies of structural and trapping parameters of gamma irradiated biochar for dosimetric applications

Biochar, a low-cost and environment-friendly material, possesses favorable physical and chemical properties towards dosimetric applications. The current investigation concentrated on the structural and thermoluminescence (TL) trapping parameters of biochar influenced by gamma-ray doses ranging from 0 to 200 Gy. The TL glow curves of gamma irradiated biochar samples have been analyzed by several well-established models viz initial rise, peak shape and curve fitting methods for estimating the fundamental trap parameters, i.e., kinetic order (b), activation energy (E) and frequency factor (s). The calculated geometric factor (μ_g) ranges between 0.50 and 0.56, indicating that the kinetic parameters can be appropriately determined using Chen's general-order kinetic model. The measured activation energy range (0.30-0.38 eV), along with the corresponding frequency factor, suggests that the biochar contains moderately stable trapping centers. These features collectively support the material's potential for reliable passive TL dosimetry, combining effective charge retention with efficient carrier release upon thermal stimulation. T_max-T_stop experiment was also performed and six subpeaks under the glow curve were located. The structural and morphological changes brought on by the radiation doses are being observed using SEM-EDX, Raman spectra and X-ray diffraction (XRD). SEM-EDX study validates the dose-dependent microstructural damage of biochar. The dose-dependent structural alterations and self-annealing with increasing gamma doses were clearly indicated by the intensity ratio (I_D/I_G), obtained from raman spectra. The crystallite size obtained from the generalized Tuinstra-Koenig equation is inversely proportional to the intensity ratio (I_D/I_G), confirms the defect generation with the increasing radiation doses. Through the examination of crystallite size (D), dislocation density (δ), lattice strain (ɛ), and FWHM from XRD patterns, additional validation of dose-dependent variation of TL trapping parameters was obtained. Analysis of the structural and trapping attributes reveals the structural alterations induced by gamma irradiation. Consequently, it is evidently noticeable that biochar possesses considerable potential for dosimetric applications.