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

The instability of Li4TiO4 to carbon dioxide (CO2) and moisture (H2O) was considered to be the main obstacle to its practical application as a tritium breeding material. Using Li2TiO3 ceramic coating as a physical barrier wrapped on the surface of Li4TiO4 pebbles was still considered to be the optimal solution. At present, increasing the thickness and strength of the Li2TiO3 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 Li2TiO3 coating on the Li4TiO4 pebble by an optimized granulation method assisted only by polyvinylpyrrolidone (PVP). The Li4TiO4-Li2TiO3 core-shell pebbles have high shell thickness (similar to 370 mu m), 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. (C) 2020 Elsevier B.V. All rights reserved.