Formation Rate and Compositions of the Actinide Hosts with Garnet Structure

摘要

Garnet phases have been considered as a durable crystalline waste form for hosting actinide. The garnet-structure phases with stoichiometries of Ca_(2,5)Ce_(0,5)Zr_2Fe_3O_(12), Ca_2CeZrFeFe_3O_(12), and Ca_(1,5)GdCe_(0,5)ZrFeFe_3O_(12) were synthesized through cold pressing and sintering in air and oxygen to determine the optimum parameters for the formation of actinide waste forms. Cerium (Ce) was used as an imitator of plutonium due to its similarity in oxidation state and ionic radii. Gadolinium (Gd) plays a major role as an absorber of neutrons that prevents nuclear chain reaction. It also serves as imitators of the trivalent actinides. Ce-garnet or (Ce,Gd)-gamet is chemically analogous to the garnets with plutonium and/or trivalent actinides. The results of XRD and SEM-EDS examination of the products of experiments reveal that equilibrium state was reached at the temperatures of 1300 ℃ and 1200 ℃ for 1 and 5 hours heating, respectively.