Pyrochlore glass-ceramics(GCs) is a waste matrix used for the immobilization of actinide-rich nuclear wastes. In this study, Gd₂Ti₂O₇ pyrochlore GCs and Ce-bearing pyrochlore GCs are prepared by two step sintering process. Firstly, the green bodies are prepared via spark plasma sintering (SPS) at 1000? with the cooling rate of 200?/min, which could ensure that the grains of pyrochlore grows hardly.  Secondly, these green bodies are submitted to different post-sintering thermal treatment in order to modify the microstructure of the pyrochlore grains in the GCs.
 
The GCs samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy(EDS), and X-ray photoelectron spectroscopy (XPS). The XRD results indicates that well-crystallized pyrochlore is the major crystalline phase synthesized from a SiO₂–B₂O₃–Na₂O–CaO–TiO₂–Al₂O₃–Gd₂O₃ system and a system with CeO₂ added. A slight lattice expansion in the pyrochlore is also found after Ce doping in the Gd₂Ti₂O₇ . It was found that the grain size of pyrochlore in the glass significant increases with the increase of the post-sintering temperature. The average grain size increases from 106.37nm at 1000? to the 1094.14nm at 1200?.
Meawhile, the grain size of pyrochlore begins to increase rapidly at 1100? which could be considered as the critical temperature of pyrochlore growth in glass. The similar phenomena is found in the system added CeO₂. However the system added CeO₂ shows a lower critical temperature of the grain growth, and the critical temperature is about 1000? . In addition, the secondary phase Gd_9.33(SiO₄)₆O₂ apatite is found in all Gd₂Ti₂O₇ GCs samples, and its content seems to be related to the SPS temperature but not so much to the post-treatment temperature.
In a word, our work use a new method including SPS and post-sintering treatment to prepare the pyrochlore GCs and provide some basic technical date for the immobilization of the actinide-rich nuclear wastes.