Investigating changes in the diffuse reflectance spectra of BaSO4 powders modified with SiO2 nanoparticles exposed to proton irradiation

Abstract

The authors modified BaSO4 powders with SiO2 nanoparticles and studied the effect of this modification on powders’ structure and optical properties, as well as on the changes of the latter after 5 keV proton irradiation. No significant post-modification changes in structure have been observed. In the IR-spectrum, the authors have recorded the band intensity changes for SiO2, Si – O – Si, and Si–Si vibrations, as well as emerging OH group vibration band. Additionally, the authors have noted the appearance of an absorption band in the UV/vis spectra caused by intrinsic point defects in BaSO4 anionic sublattice. The energy losses induced by displacement and ionization were calculated, as were the proton free paths in the modified powder. It is shown that an increase of radiation stability is provided by solely 1.2% of the proton energy flux absorbed in the nSiO2 nanolayer contributing to the total energy loss in the entire modified powder. Two mechanisms are proposed for the processes occurring in the nSiO2/mBaSO4 system that determine the increase of its radiation stability compared with the non-modified powder.