C/a Ratio-dependent energy-storage density in (0.9-x) Bi _0.5Na_0.5TiO₃-xBaTiO₃-0.1K _0.5Na_0.5NbO₃ ceramics

The (0.9-x)Bi_0.5Na_0.5TiO₃-xBaTiO ₃-0.1K_0.5Na_0.5NbO₃ [BNBKN(x), x = 0.060, 0.063, 0.066, and 0.069] ceramics were fabricated by the conventional sintering technique. The P-E hysteresis loops measured under 5 kV/mm at room temperature show that the BNBKN(0.063) ceramics obtain the maximum (Ps-Pr) value of 20.6 μC/cm² and the largest energy-storage density W of 0.424 J/cm³. In addition, calculation from the X-ray diffraction results shows that the BNBKN(0.063) ceramics are featured with the largest c/a ratio of 0.70887. The W is observed to increase with the increase of the c/a ratio in the BNBKN(x) ceramics. The c/a ratio can be regarded as a significant factor for W in the BNBKN(x) ceramics.