Solubility of Ce4+ and Sr2+ in the pyrochlore lattice of Gd2Zr2O7 for simulation of Pu and alkaline earth metal

The solubility of Ce4+ and Sr2+ 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 Gd2Zr2O7 by the A site substitution. A number of compositions with general stoichiometry Gd2−xSrxZr2O7−x/2 and Gd2−xSrx/2Cex/2Zr2O7 have been synthesized and characterized by powder XRD. From the XRD data, the solubility of Sr2+ is estimated to be about 1.25 mol%. Further addition of Sr2+ leads the separation of SrZrO3 perovskite phase. The solubility of Sr2+ increases to 2.5 mol% when substituted in combination with Ce4+. The solubility of Ce4+ is estimated to be about 12.5 mol% in the pyrochlore lattice of Gd2Zr2O7. Further addition of Ce4+ into the pyrochlore lattice leads to the formation of fluorite phase.