Stability studies of [CsxBay][(Al3+,Ti3+)2y+xTi8-2y-x4+]O16 ceramics for radioactive caesium immobilization

[CsxBay][(Al3+, Ti3+)(2y+x)Ti-8-2y-x(4+)]O-16 (0.4 <= x, y <= 0.8) ceramics were synthesized to investigate the substitution effects of Ba2+ for Cs+ on the stability of hollandite-ceramic waste forms. It was found that the substitution of Ba2+ for Cs+ in the (Cs,Ba)-hollandite system does not cause substantial variation in the crystallographic phase and microstructure. The normalized release rates of Cs and Ba at 90 degrees C in deionized water were < 0.005 g m(-2) d(-1) after 28 days. These results indicate that hollandite ceramics are an ideal host for permanent radioactive caesium disposal.