fig7

Figure 7. (A) Unipolar P-E loops of 0.60BT-0.40NN ceramics measured under 19 MV m^-1 at various frequencies, (C) under 15 MV m^-1 at different cycles and (E) under 20 MV m^-1 at various temperatures. Corresponding (B) frequency-dependent, (D) fatigue-dependent and (F) temperature-dependent energy storage properties.