Preparation of Li4TiO4-Li2TiO3 core-shell ceramic pebbles with thick shells and high strength through an improved granulation method

The instability of Li 4 TiO 4 to carbon dioxide (CO 2 ) and moisture (H 2 O) was considered to be the main obstacle to its practical application as a tritium breeding material. Using Li 2 TiO 3 ceramic coating as a physical barrier wrapped on the surface of Li 4 TiO 4 pebbles was still considered to be the optimal solution. At present, increasing the thickness and strength of the Li 2 TiO 3 coating to increase the service life of this core-shell pebble has become an urgent problem to be solved. In this study, we successfully wrapped a thick and uniform Li 2 TiO 3 coating on the Li 4 TiO 4 pebble by an optimized granulation method assisted only by polyvinylpyrrolidone (PVP). The Li 4 TiO 4 -Li 2 TiO 3 core-shell pebbles have high shell thickness (∼370 µm), relatively high wall thickness uniformity (78.86±3.07%) and good sphericity (90.72±1.88%) with a crush load of 47.73±1.49 N. It was demonstrated that PVP not only plays the role of bridge bonding between powders but also serves as a template to induce powder to be assembled layer by layer to form a uniform core-shell structure.