Impact of annealing temperatures on evolutionary structure, internal defects, and X- and Gamma-Radiation Shielding in WO3

Current research focuses exclusively on the particle size of materials to potentially enhance their ability to protect against ionizing radiation. This research investigates, for the first time, the microstructural alterations in WO₃ annealed at elevated temperatures and their effects on ionizing radiation shielding. The synthesized samples exhibited distinct color changes with increasing annealing temperatures. XRD and Raman measurements confirmed the monoclinic γ-WO₃ phase. The annealing-induced morphological transformations of WO₃ show that at 500 °C, the particles are predominantly nanorods, whereas at 700 °C, they resemble hexagonal-like nanosheets. Notably, the mean particle size of the nanosheets drops at 950 °C and then rises to a microscale at 1100 °C. The annealing process plays a crucial role in mitigating pores and defects, revealed by isothermal adsorption-desorption and positron annihilation lifetime (PAL), respectively. In general, raising the temperature has a positive effect on the X- and γ-ray attenuation of the samples. Multivariate analysis highlighted the key parameters influencing radiation shielding. While, depending on the energy, X-ray attenuation has distinct correlations with certain microstructural factors, including particle size, crystallite size, and pore characteristics, the attenuation of γ-ray is primarily dependent only on defect characteristics. The results demonstrate that relying solely on particle size is inadequate and that the interrelated microstructural factors need to be taken into account when evaluating the shielding properties of materials. This study offers valuable insights into the structural characteristics of WO₃ and its potential applications in radiation shielding, emphasizing the necessity for further studies to establish precise material-specific guidelines.