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Page 8 of 13 Xu et al. Microstructures 2023;3:2023034 https://dx.doi.org/10.20517/microstructures.2023.19

Figure 7. Unipolar P-E hysteresis loops (A and D), the corresponding energy storage properties (B and E), and P , ΔP, and P (C and F)
max r
for 0.08 SMZ ceramics at different frequencies and temperatures under different electric fields.

Figure 8. Breakdown paths for (1-x)NN-xSMZ samples under various times. x = 0: Figure 8A -A , x = 0.08: Figure 8B -B .
1 3 1 3
ceramics experienced a rapid electrical breakdown. The breakdown simulation of the 0.08 SMZ sample is
shown in Figure 8B1-B3, and the electrical tree branch phenomenon of the sample can be clearly observed.
The reason for this difference is that the average grain sizes of 0.08 SMZ ceramics were much smaller than
those of pure NaNbO ceramics. The smaller grain sizes were beneficial to generate more energy dissipation
3
regions to suppress the breakdown behavior, which was manifested as the phenomenon of electrical tree
branches. Usually, the more branches indicated that the material was more difficult to be broken down,
which can also be proved by the marking time.