Li₄SiO₄ based breeder ceramics with Li₂TiO₃, LiAlO₂ and Li_XLa_YTiO₃ additions, part I: Fabrication

Highlights: • This study shows that the emulsion method can easily be adapted to add different phases into Li4SiO4 breeder pebbles. • Slurries with various compositions to form LOS + LMT, LOS + LAO and LOS + LLTO were processed.The calculated activation behavior shows that samples with added LAO or LLTO qualify as low activation material. • Yet, the long-term activation of the LAO containing samples is problematic as hands-on level activity is not reached quickly. - Abstract: Wet-chemical fabrication processes are highly adaptable to a wide range of raw materials and are therefore well suited for evaluating new material compositions. Here the established emulsion method was modified to fabricate novel two-phase Li₄SiO₄ pebbles of 1 mm diameter with additions of Li₂TiO₃, LiAlO₂ or Li_xLa_yTiO₃. As the lithium density of the latter two compounds is relatively low, only moderate contents were added. The Li₂TiO₃ additions, however, cover the full compositional range. The fabrication process was characterized with regard to its constancy and aptness for the anticipated pebble compositions by optical pebble size measurements. Also the phase content and the elemental composition of the fabricated pebbles were analyzed by XRD and ICP-OES combined with XRF, respectively. This work shows that the emulsion method is an appropriate method to produce pebbles with the anticipated Li₂TiO₃ and LiAlO₂ concentrations in a Li₄SiO₄ matrix. However, Li₄SiO₄ and Li_xLa_yTiO₃ react with each other to a number of different phases. To evaluate the activation properties of the pebbles, FISPACT calculations with a DEMO relevant neutron source are applied as well. The addition of aluminum seems to be unfavorable for a fusion application, but moderate concentrations of lanthanum can be tolerated.