The influence of gamma-irradiation on molecular structure and mass attenuation coefficients of gamma-Al2O3 nanoparticles

In this research, gamma-Al2O3 nanoparticles (NPs) were synthesized by using the sol-gel process. The photon attenuation properties of these NPs were obtained by measuring the linear and mass attenuation coefficients (mu(l), mu(m)) at different photon energies. In addition, the theoretical values of mu(m) for gamma-Al2O3 micro-particles were calculated using the WinXCom computer program and compared with the experimental values of mu(m) for NPs of gamma-Al2O3. Furthermore, in order to evaluate the impact of gamma-irradiation on these NPs, the experimental values of mu(l) and mu(m) for gamma-Al2O3 NPs, before and after receiving 20 kGy dose of gamma-irradiation, were investigated. It was observed that mu(m) of gamma-Al2O3 NPs decreases after receiving gamma-irradiation because of increasing the photon's energy, which indicates the changes in the molecular structure of NPs after gamma-irradiation. Moreover, the structural properties of NPs were evaluated by UV-Vis spectroscopy, x-ray diffraction patterns, and scanning electron microscopy images. UV-Vis spectroscopy showed an absorption peak at 212.5 nm before gamma-irradiation, and the absorption peak of NPs disappeared when gamma-irradiation was started. The average crystalline size was determined to be 3.65 nm in the sample before gamma-irradiation and 9.29 nm in the sample with the maximum dose of 20 kGy. The results of scanning electron microscopy show an increase in particle size from 6.5 nm in a non-irradiated sample up to 9 nm in a sample with the highest gamma-irradiation dose.