Published online by Cambridge University Press: 25 February 2011
The radiation stability of polyphase titanate ceramic waste forms was studied using analytical transmission electron microscopy, in combination with in situ irradiation by 30 keV He ions, followed by staged annealing. Two experiments were conducted. In the first, a reconnaissance investigation was made of the stabilities of the synthetic minerals hollandite, zirconolite, and perovskite when subjected to a total dose of 1.8 × 1017 He+ cm-2. It was found that all phases amorphized at approximately the same rate, but perovskite recovered its structure more rapidly and at lower temperatures than the other phases. In particular, annealing for 10 minutes at 1000°C was sufficient for perovskite to completely regain its crystallinity, while zirconolite and hollandite were only partially restored by these conditions. In the second experiment, the response of a thin hollandite crystal to irradiation was examined by selected area electron diffraction. At a dose of 1.5 × 1015 He+ cm-2its incommensurate superstructure was disrupted, but even at a dose of 3 × 1016 He cm-2 the hollandite subcell was largely intact. For this dose, total recovery was achieved by annealing for 1 minute at 1000°C.