Radiation-induced nanoparticle formation under steady-state radiolysis: comparison of the Fe, Co and Cr systems

This work involves a comparative study of γ-radiation-induced nanoparticle formation under steady-state irradiation of the Fe, Cr, and Co systems. Water containing initially dissolved metal ions was irradiated in a ⁶⁰Co γ-cell. The resulting nanoparticles were characterized using FTIR spectroscopy, Raman spectroscopy and XPS. Transmission electron microscopy (TEM) was used to identify the size and shape of the particles. The mechanisms for the formation of γ-FeOOH, Cr₂O₃ and Co₃O₄ nanoparticles are discussed. Depending on the redox potential of the metallic species, either oxidizing or reducing water radiolysis products are responsible for the generation of particle nucleation sites and particle growth. Other key factors that control nanoparticle formation are the pH of the solution and the initial oxygenation of the solution. (author)