Self-propagating synthesis and CeO 2 immobilization of zirconolite-rich composites using CuO as the oxidant

Two‐step synthesis of zirconolite‐rich ceramic waste matrice and its physicochemical properties

“…The 1 day LR Ca is 9.50×10 −2 g·m −2 ·d −1 , which declines to 3.96×10 −3 g·m −2 ·d −1 after 42 days leaching. Compared with our previously synthesized zirconolite‐rich waste forms using combustion synthesis, the LR Ca value is about one magnitude lower in this study. The sample after combustion synthesis is not under very stable state, which is harmful for the chemical stability.…”

“…Recently, we have prepared zirconolite‐rich waste forms using in‐situ combustion synthesis (CS), where Ca(NO 3 ) 2 , MoO 3 , and CuO were employed as the oxidants with Ti as the reductant . Zirconolite‐rich composites were rapidly synthesized within 3 minutes using this CS technique.…”

“…Recently, we have prepared zirconolite-rich waste forms using in-situ combustion synthesis (CS), where Ca(NO 3 ) 2 , MoO 3 , and CuO were employed as the oxidants with Ti as the reductant. [24][25][26][27] Zirconolite-rich composites were rapidly synthesized within 3 minutes using this CS technique. In this study, the synthesis of single-phase zirconolite was explored on the basis of CS preparation of zirconolite.…”

Synchrotron x‐ray spectroscopy investigation of the Ca1−xLnxZrTi2−x(Al, Fe)xO7 zirconolite ceramics (Ln = La, Nd, Gd, Ho, Yb)

“…In some cases, actinides present in form of tetra‐valence state (such as U 4+ , Pu 4+ , Np 4+ , Th 4+ ). Hence, some researchers focused on immobilizing them (or nonradioactive Ce 4+ as succedaneum) into the Zr site of zirconolite to study their solubility and microstructure modification . Clark et al found that zirconolite‐4M appeared at x = 0.2 and single pyrochlore phase was observed at x = 1 for CaZr 1− x Ce x Ti 2 O 7 solid solutions .…”

“…Clark et al found that zirconolite‐4M appeared at x = 0.2 and single pyrochlore phase was observed at x = 1 for CaZr 1− x Ce x Ti 2 O 7 solid solutions . Zhang et al pointed out that Ce preferentially occupies the Ca site of perovskite rather than the Zr site of zirconolite when prepare the nominal CaZr 1− x Ce x Ti 2 O 7 solid solution by self‐propagating high‐temperature synthesis (SHS) due to the reduction of Ce 4+ to Ce 3+ during SHS reaction …”