Double polarization hysteresis and dramatic influence of small compositional variations on the electrical properties in Bi4Ti3O12 ceramics

This work reports the existence of double polarization hysteresis (P-E) loop in Aurivillius-phase ferroelectric Bi4Ti3O12 (BiT) and reveals dramatic influence of small compositional variations on the electrical properties of it. The double polarization hysteresis is a characteristic of the interaction of defects with domain walls. This characteristic becomes more pronounced in Bi-deficient and Mg-doped BiT due to an increase in oxygen vacancy concentration at the lattices. Normal and saturated P-E loop is recalled by Nb donor doping, and associated composition Bi4Ti2.97Nb0.03O12.015 (BiT-0.03Nb) shows high remnant polarization (P-r = 12.5 mu C/cm(2)) and large field-induced strain (S-33 = 5.6 x 10(-4)). In addition, this doping results in bulk conductivity (sigma(b)) of BiT decreasing dramatically and associated activity energy (E-a) increasing significantly. In contrast, high oxide ion conductivity is induced with Mg2+ acceptor doping, and at 600 degrees C the optimum composition has ionic conductivity of (similar to)0.65 x 10(-2) S cm(-1) in the bulk.