Fabrication and phase transition of Gd2Zr2O7 ceramics immobilized various simulated radionuclides

To investigate the feasibility of Gd2Zr2O7 used for disposal waste of multi-nuclides with multi-valence, simulated trialkyl phosphine oxides (TRPO) waste was chosen to research the fabrication method and phase evolution. A series of (Gd,A)(2)(Zr,B)(2)O-7 ceramics were successfully fabricated through a solid-state reaction sintering at 1500 degrees C for 72 h. XRD studies reveal that the compositions containing up to 35 wt.% simulated TRPO waste exhibit a single pyrochlore structure, while the doping content varies from 35 to 65 wt.%, the samples adopt a single defect fluorite structure. In the discussed range, the lattice parameter decreases with the increased doping content, and the r(A)/r(B) ratio decreases from 1.43 to 1.27, while the degree order increases in turn. Furthermore, the densification and grain growth in pyrochlore structure are promoted by an enhanced doping content. (C) 2014 Elsevier B.V. All rights reserved.