Long-term thermal stability of two-phased lithium orthosilicate/metatitanate ceramics

The long-term thermal stability of advanced ceramic breeder pebbles consisting of lithium orthosilicate (Li4SiO4) and additions of lithium metatitanate (Li2TiO3) was tested in an annealing experiment at 900 °C for up to 128 days. Different gas atmospheres were used to test the influence of moisture in the purge gas. Li4SiO4 pebbles including nominally 25, 30, and 35 mol% Li2TiO3 were investigated with regard to their chemical composition, microstructure, porosity, and mechanical properties after predetermined time intervals and at the end of the experiment. No lithium loss and no secondary phases were detected. The microstructures, porosities and mechanical stabilities did not show significant changes over time. Moreover, moisture in the purge gas atmosphere has no negative influence on the material properties.