Doped Bi0.5Na0.5TiO3-PbTiO3 relaxor ferroelectric ceramics

Bismuth Sodium Titanate (Bi0.5Na0.5TiO3) is an attractive complex perovskite ferroelectric for lead-free ceramic material. The phase transition at 320°C corresponds to the maximum of dielectric permittivity. An additional phase transition is shown by a hump on the dielectric permitivity curve at about 220°C. However, doped with Pb this material gives a higher dielectric constant with a broadened phase transition and high resistivity. The x-ray data shows a phase boundary at 17% Pb for this system. The temperature of the maximum of dielectric permittivity for this system is almost constant at different frequencies. The effect of a La dopant in a 0.9Bi0.5Na0.5TiO3-0.1PbTiO3 based solid solution can stabilize the dielectric constant with temperature.