Low-temperature synthesis of Li2TiO3 tritium breeder ceramic pebbles by water controlled-release solvothermal process

Abstract

In this work, the water-controlled release solvothermal process (WCRSP) method was selected to synthesize nanostructured β-Li2TiO3 tritium breeder ceramic pebbles using anhydrous lithium acetate (LiOAc) as lithium source and tetrabutyl titanate (TBOT) as titanium source. The effects of the reaction system, temperature, and amount of acetic acid on the crystal structure and morphology of Li2TiO3 power were systematically investigated by using XRD, SEM, and TEM techniques, respectively. The urea or acetone in the reaction system affects the composition of Li2TiO3 in the water-controlled release solvothermal process at 550 °C. Initially, the nanostructured single-phase Li2TiO3 powders with good dispersion and an average particle size of 35 nm were successfully synthesized at 550 °C when the acetic acid content was 15 vol%. Moreover, the phase transition temperature for the monoclinic phase β-Li2TiO3 was as low as 450 °C. The morphology of Li2TiO3 powder presents two different shapes, one is micro-spherical, the other is spherical nanoparticles in different content acetic acid. The results indicate that using ethanol/acetic acid mixture as a reaction system is favorable for obtaining nanostructured Li2TiO3 powder. Finally, Li2TiO3 ceramic pebbles with grain size of 1.4 μm were successfully fabricated at 950 °C for 2 h at room temperature, and the crush load and relative density (theoretical density, T.D) of the pebbles reach 53 N and 85.2%, respectively.