Rapid solidification synthesis of novel (La,Y)2(Zr,Ti)2O7 pyrochlore-based glass-ceramics for the immobilization of high-level wastes

Abstract

Pyrochlore-based glass-ceramics are attracting attention as a promising host material for immobilizing minor actinide in high-level wastes. However, the loading capacity of pyrochlore-based materials for actinide elements is to be improved, and only conventional synthetic approaches of powder sintering and glassy bulk crystallization were reported. Here, new (La,Y)2(Zr,Ti)2O7 pyrochlore-based glass-ceramics were subtly designed and successfully prepared through a rapid melting and solidification process. The solidification behavior of samples with different cooling rates was investigated, the dense and crack-free (La,Y)2(Zr,Ti)2O7 pyrochlore-based glass-ceramics were prepared at the cooling rate of 500 °C/s (within 1.5 s). The present amorphous La2O3-TiO2-Al2O3 phase demonstrates the outstanding thermal stability compared with the currently used borosilicate glass for high-level waste immobilization due to the lack of conventional glass-forming components. The results show the great feasibility of this novel synthesis route for glass-ceramics by direct solidification and its good potential for immobilizing high-level wastes.