Synthesis of Gd₂Zr₂O₇ Pyrochlore With Cubic Structure at High Pressure and High Temperature Conditions

In order to investigate the possibility to synthesize cubic pyrochlore Gd₂Zr₂O₇ by solid-solid reactions under high pressure and high temperature conditions, the synthesis experiments were carried out at a fixed pressure of 5.2 GPa and a temperature range of 1 473-1 873 K using the mixed powders of Gd₂O₃ and ZrO₂ as starting materials. The as synthesized samples were characterized by XRD. The results show that a single phase compound Gd₂Zr₂O₇ with a cubic pyrochlore structure is successfully synthesized at 5.2 GPa pressure and 1 873 K temperature with 30 min holding time. The novel method has vitally scientific values and practical significance for immobilization of surplus weapon-level plutonium and containing-plutonium high level wastes.