Ming Zhang

By Ming Zhang

The stabilization and immobilization of high‐level radioactive wastes in solid forms have become one of the most pressing industrial problems. Different crystalline mineral phases have been proposed as actinide‐bearing crystalline hosts for waste materials. Self‐radiation damage from alpha‐decay of the incorporated actinides (such as U, Th) and other rare earth elements can lead to metamict state (amorphous state) and can affect the durability and long‐term performance of these actinide‐bearing phases. To investigate the impact of radiation on the nuclear waste forms and to obtain a better comprehension of the damage process and amorphization mechanism are important. The issues of interactions between high‐energy particles and solids and radiation‐induced structural modifications in crystalline‐to‐amorphous state are, in fact, an important and active area of fundamental researches. To study metamict state and metamictization is also important for geochemistry as the U‐Pb isotope system is commonly used for age dating. Although radiation effect and naturally occurring radiation damage (the process is known as metamictization) have been the subject for many research investigations, there remain important and fundamental issues which need to be understood, for example, the structural changes at the atomic level caused by metamictization, the crystal structure of radiation‐induced amorphous phases, solubility and diffusion of radioactive elements in damaged host phases, the effect of pressure and temperature on metamictization process and interaction of water and fluids with nuclear waste forms. Raman spectroscopy is found to be a very powerful tool for study and analysis of the damage effect and metamictization. This chapter describes and reviews recent Raman applications in zircon and titanite, which are proposed for nuclear waste forms. These applications are focused on radiation effect and structural damage process caused by alpha‐decay process as well as recrystallization due to thermal annealing.

Part of the book: Raman Spectroscopy and Applications