Comparative study of K0.5Bi0.5TiO3 nanoparticles derived from sol-gel-hydrothermal and sol-gel routes

A kind of novel lead-free ferroelectrics, potassium bismuth titanate, K_0.5Bi_0.5TiO₃ (KBT), has been prepared by sol-gel-hydrothermal and sol-gel routes, respectively, and the structural characters of as-synthesized powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results indicated that sol-gel-hydrothermal route led to the formation of KBT nanowhiskers with diameters of 20 nm and lengths of 1 μm, and the processing temperature was as low as 160 °C, but the normal sol-gel route tended to form KBT cubic particles of about 100-200 nm, and the processing temperature was higher than 700 °C. It is believed that the gel precursor and hydrothermal environment play an important role in the formation of the nanowhiskers at low temperature. Due to the good sinterability of nanowhiskers, the ferroelectric and dielectric properties of KBT ceramics prepared by sol-gel-hydrothermal route were super to that prepared by sol-gel route.