Low temperature fabrication of Ba0.9Cs0.3Cr2.1Ti5.9O16 ceramic waste form for cesium immobilization using Bi2O3 as sintering aid

In this paper, we present a productive low-temperature fabrication of Cs-hollandite ceramics by adding Bi 2 O 3 as a sintering aid to achieve high cesium retention. The effects of Bi 2 O 3 addition on the phase composition, crystal structure and aqueous stability of the stoichiometric Ba 0.9 Cs 0.3 Cr 2.1 Ti 5.9 O 16 ceramic waste form were investigated. It was found that adding Bi 2 O 3 can effectively reduce the sintering temperature and promote densification of Cs-containing hollandite products. The Cs-hollandite ceramic with 2 wt% Bi 2 O 3 sintered at 1000 °C showed a single phase with > 98 % cesium retention, which was ∼ 200 °C lower and ∼ 11 % retention rate higher than those of reported Cs-bearing hollandite. Moreover, the leached sample remained stable tetragonal structure, the LR Cs was in the order of 10 -3 g·m - 2 ·d -1 after 28 days and the leaching indexes > 8, exhibiting good aqueous stability. This route can be considered as a promising solution to prevent cesium loss for incorporating the cesium waste in ceramic hosts.