Unusual dynamic polarization response and scaling behaviors in Bi1/2Na1/2TiO3 ceramics

The excellent electrical properties and potential applications of ferroelectric ceramics are intrinsically correlated with the dynamic polarization response under applied electric field. However, the lack of clarity with regard to global polarization reversal process has hindered the understanding of the functional properties. Here, the polarization reversal and dynamic hysteresis were investigated in (Bi_1/2Na_1/2)TiO₃ (BNT) ceramics. The scaling behaviors were presented by studying the field amplitude E₀, frequency f₀ and temperature T₀ dependence of hysteresis loops. Three new features of polarization responses and scaling behaviors were obtained. First, the exponent α in the hysteresis loop area A>∝E₀^α equation displayed large values in high-E₀ stage. Then, the A> displayed an abnormal increase with increasing temperature. Finally, a near frequency-invariant coercive field E_C, accompanied by a weak dependent P_r and A>, was observed. The correlation between these new features and polarization extension/rotation as well as complex domain structure and field-induced phase transition was demonstrated.