The strain response of the
Temperature dependence of dielectric constant and loss for both unpoled and poled textured ceramics of BNT–BKT–5ST is contrasted, as shown in Fig. 5(a) and (b), respectively. The measurement frequency increases from 1 kHz to 200 kHz along the directions of the allows, as marked in Fig. 5. There are two distinctive dielectric anomalies evident in dielectric constant and loss for both unpoled and poled ceramics: a shoulder at a lower temperature with a strong frequency dispersion and frequency-insensitive peaks at a higher temperature, which indicates that CA-074 Me the BNT–BKT–5ST textured ceramics exhibits relaxor characteristics  and . Jo et al.  and  proposed that the origin of the commonly observed two dielectric anomalies in BNT-based systems can be understood as a convolution of three distinctive processes as follows: a dielectric relaxation at low temperature contributed by coexisting PNRs of different symmetries, a diffuse phase transition at intermediate temperature derived from low symmetry PNRs to higher symmetry ones, and an additional dielectric relaxation process at high temperature originated from the remaining high symmetry PNRs. After the poling treatment, a clear difference of the profile between dielectric constant and loss is revealed by an additional dielectric anomaly, as presented in Fig. 5(b). This anomaly is commonly referred to as ferroelectric-to-relaxor transition temperature (TF-R) marked by dashed line, where a field-induced FE order converts back to an ergodic relaxor state  and . It is noted that TF-R is determined by the frequency-independent peak in the dielectric loss and the determination of producers is only valid for poled samples , , ,  and , as depicted in Fig. 5(b).