We note that a drift of unipolar polarization curves has been observed for the BCZT sample upon unipolar cycling, which has not been observed in the other samples (Figure ). Additionally, the measurement of the frequency-dependent dielectric losses revealed an increased loss at frequencies below 1 Hz for the two samples without A-site compensation (Figure ). This suggests the presence of charge carriers, which become mobile at low frequencies and contribute to conductivity. The increase in dielectric loss is smaller in the BCZT-A sample, indicating that it has fewer mobile defects in the matrix and likely a better match to the desired A:B = 1:1 stoichiometric ratio.