Solubility of Ce~(4+) and Sr~(2+) in the pyrochlore lattice of Gd_2Zr_2O_7 for simulation of Pu and alkaline earth metal

摘要

The solubility of Ce~(4+) and Sr~(2+) has been studied for the simulation of plutonium, and alkaline-earth metal elements, which are the common fission products in a nuclear fuel, in the zirconate pyrochlore lattice of Gd_2Zr_2O_7 by the A site substitution. A number of compositions with general stoichiometry Gd_(2-x)Sr_xZr_2O_(7-x/2) and Gd_(2-x)Sr_(x/2)Ce_(x/2)Zr_2O_7 have been synthesized and characterized by powder XRD. From the XRD data, the solubility of Sr~(2+) is estimated to be about 1.25 mol percent. Further addition of Sr~(2+) leads the separation of SrZrO_3 perovskite phase. The solubility of Sr~(2+) increases to 2.5 mol percent when substituted in combination with Ce~(4+). The solubility of Ce~(4+) is estimated to be about 12.5 mol percent in the pyrochlore lattice of Gd_2Zr_2O_7. Further addition of Ce~(4+) into the pyrochlore lattice leads to the formation of fluorite phase.