In-situ generation of Li2TiO3/Li2SiO3 particles in Li4SiO4 using TiO2 addition for grain refinement and improved thermal cycling stability
Multiphase composites of lithium ceramics have emerged as a prominent area of research in the development of advanced solid tritium breeding materials. In this study, Li 2 TiO 3 /Li 2 SiO 3 co-doped Li 4 SiO 4 ceramic pebbles were prepared through an in-situ reaction between Li 4 SiO 4 and TiO 2 . The objective of this study is to enhance the thermal cycling stability of Li 4 SiO 4 by impeding the grain boundary migration of Li 4 SiO 4 under high temperature conditions. The effects of the in-situ generated Li 2 TiO 3 /Li 2 SiO 3 particles on the microstructure, crush load and thermal cycling stability of Li 4 SiO 4 ceramic pebbles were investigated. The in-situ formed Li 2 TiO 3 and Li 2 SiO 3 particles effectively hindered the grain growth and minimized the formation of large intracrystalline pores in Li 4 SiO 4 . At a sintering temperature of 900 °C, the Li 2 TiO 3 /Li 2 SiO 3 particles are beneficial in increasing the crush load of Li 4 SiO 4 ceramic. However, at lower sintering temperatures, their impact was counterproductive. An increase in the volume fractions of the Li 2 TiO 3 /Li 2 SiO 3 had a positive effect on grain refinement but a negative effect on crush load. The Li 2 TiO 3 /Li 2 SiO 3 co-doped Li 4 SiO 4 ceramic pebbles exhibited excellent structural stability during thermal cycling. The optimum mechanical stability was achieved at a TiO 2 addition of y = 0.1. The in-situ generated fine second phase particles effectively impeded grain boundary migration at high temperatures, providing a viable strategy for improving the thermal stability of Li 4 SiO 4 tritium breeders.
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