The effect of domain switching on the lattice symmetry and dielectric properties of (Bi0.5Na0.3K0.2)TiO3–0.2SrTiO3-(Ba0.8Ca0.2)TiO3 piezo-ceramic by poling field

Abstract

The present study illustrates the effect of domain switching on the structural, dielectric, and piezoelectric properties of [0.75(Bi0.5Na0.3K0.2)Ti O3-0.2SrTi O3-0.05(Ba0.8Ca0.2)Ti O3] (i.e., BNKT- ST-BCT) Pb-free ceramic caused by poling effect. The sample has been synthesized by the solid reaction technique. The poling conditions were changed from (10–50 kV/cm) for 30 min at 100 °C. The pristine ceramic sample showed pseudo-cubic crystal structure, while tetragonal structure was detected for all the poled samples. The pristine sample showed a normal ferroelectric loop with a low coercive field (Ec =12 kV/cm) owing to the domain grow caused by domain wall displacement. The effect of poling field into Raman spectra showed variation the volume fraction of orthorhombic and tetragonal phases. Increasing the intensity of the tetragonal phase is related to the increase in lattice symmetry of the poled samples at a high poling field. Relaxor to paraelectric phase transition was observed at Burn's temperature (TB) of the un-poled sample, while the poled rates undergo a ferroelectric to relaxor phase transition at depolarization temperature (Td). In the regime of the sub-switching domain, the maximum permittivity was found to increase by poling field due to Rayleigh effect, while at high poling field it was observed to decrease due to tunability effect. The maximum current peak of relaxor to ferroelectric phase transition was observed to mitigate by increasing the poling effect. The converse piezoelectric coefficient, (d33∗) was achieved to be higher in the un-poled sample due to the lowest crystal symmetry in the absence of a poling effect. The existence of poling process leads to shrink both current peak and (d33∗) values, indicating the dominated of the tetragonal phase rather than the orthorhombic phase. Such results offer distinct features of an un-poled ceramic sample that make it suitable for different technological applications such as energy storage devices, sensors, and actuators.