Spark Plasma Sintering Temperature Effect on Structural, Dielectric and Ferroelectric Properties of Ba_0.9Sr_0.1TiO₃ Nanocrystalline Ceramics

A combination of mechanical alloying and spark plasma sintering (SPS) was used to process Ba_0.9Sr_0.1TiO₃ (abbreviated as BST) with a high-density and homogeneous microstructure, at a temperature 300°C to 400°C lower than that used in conventional sintering. The SPS technique was employed to prepare dense Ba_0.9Sr_0.1TiO₃ nano-ceramics at different temperatures ranging from 800°C to 1000°C within a very short time. The SPS samples were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, electrical, ferroelectric and piezoelectric property measurements. The dielectric constant both at room temperature and Curie temperature increased with increasing SPS temperature. The coercive field increased continuously with rising SPS temperature, but the spontaneous polarization increased gradually up to 900°C and then decreased considerably with further increases in SPS temperature. In addition, the prepared nano-ceramic exhibited excellent piezoelectric properties.