An advanced core-shell ceramic pebble with Li 4 TiO 4 pure phase core and Li 2 TiO 3 nanostructured shell was prepared by a physical coating method. The phase compositions, morphology and microstructure of Li 4 TiO 4 –Li 2 TiO 3 core-shell ceramic pebbles were investigated. We discovered that using chitosan solution to assist rolling coating helps to improve the coating uniformity of core-shell green pebbles. In addition, the results show that the obtained Li 4 TiO 4 –Li 2 TiO 3 core-shell ceramic pebbles have a diameter of ∼1.1 mm, the shell thickness of ∼13 μm and density of 2.31 ± 0.03 g/cm 3 . It is also noted that the Li 2 TiO 3 shell still maintains the nanostructure (∼80 nm) after sintering. This study provides a feasible method for preparing Li 4 TiO 4 –Li 2 TiO 3 core-shell ceramic pebbles which have a great potential application for the test blanket module (TBM) of International Thermonuclear Experimental Reactor (ITER).
A tetralithium titanium (Li4TiO4) compound is a tritium breeder material that deserves serious consideration for the fusion reactor blanket concept because of its high lithium density. In the current research, an experimental investigation was conducted for the first time to verify the calculated simulation results. First, the lattice parameters, energy band structures, and thermodynamic properties of Li4TiO4 are investigated by means of first-principles density functional theory. Then, the Li4TiO4 powder was synthesized via a solid-state reaction. Subsequently, the samples were systematically characterized using various measurement techniques. The products of the ultraviolet diffuse reflection spectrum, Raman spectroscopy, and laser thermal conductivity are consistent with the theoretical calculations.
Ruichong Chen,Zhijun Liao,Yanli Shi,Hailiang Wang,Hao Guo,Yuanyuan Zeng,Jianqi Qi,Qiwu Shi,Tiecheng Lu
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.
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