Spark plasma sintering of Ca _1-xSr _xTiO ₃ doped with Li ₂Si ₂O ₅

Spark plasma sintering (SPS) of Ca _1-xSr _xTiO ₃ was conducted with and without an Li ₂Si ₂O ₅ additive at 1170°C for 4 min. A single phase, Cai _1-xSr _xTiO ₃ solid solution was formed; moreover, the mechanical and dielectric properties were improved by adding 0.5 wt% Li ₂Si ₂O ₅. Conversely, in the absence of Li ₂Si ₂O ₅, a mixture of Ruddlesden-Popper phases Sr _n+1 Ti _nO _3n+1 and rutile TiO ₂ was formed in addition to Ca _1-xSr _x TiO ₃ although a single phase Ca _1-xSr _xTiO ₃ could be formed via pressureless sintering at 1200°C for 2 h in air. These results suggested that Li ₂Si ₂O ₅ was useful even via an SPS technique to promote the mass transfer, and its optimum concentration was 0.5 wt%.