标题:Atomistic scale investigation of cation ordering and phase stability in Cs-substituted Ba1.33Zn1.33Ti6.67O16, Ba1.33Ga2.66Ti5.67O16 and Ba1.33Al2.66Ti5.33O16 hollandite
摘要:), the presence of both Cs and Ba in the A-site tunnels is not energetically favored. However, the decay heat generated during storage of the Cs-containing waste form may overcome the energetics of Ba and Cs mixing in the tunnel structure of hollandite. The ability of the hollandite structure to accommodate the radioparagenesis of Cs to Ba is critical for long term performance of the waste. For the first time, B-site ordering was observed along the tunnel direction ([001] zone axis) for the Ga-hollandite compositions, as well as the intermediate Al-hollandite composition. These compositionally dependent structural features, and associated formation enthalpies, are of importance to the stability and radiation damage tolerance of ceramic waste forms.