Published online by Cambridge University Press: 17 March 2011
Hollandite, based on Ba and Ti, has been shown to be an ideal medium by which active 135Cs and 137Cs can be immobilised. Diffraction measurements have shown that Cs modifies the symmetry of the material, from monoclinic to tetragonal. Experiments carried out here show the effects of Cs on two hollandite systems based on Ba-Al-Ti and Ba-Mg-Ti. Structural measurements are reported for neutron diffraction, and MAS NMR. The results show that Cs modifies the overall crystal symmetry while having little effect on the order/disorder of Al-Ti and Mg-Ti octahedra.