Enhanced energy storage properties of NaNbO₃ modified Bi_0.5Na_0.5TiO₃ based ceramics

(1-x)BNTBT-xNN ceramics were prepared by conventional solid state reaction method. X-ray fluorescence analysis shows that the volatilization of Na element occurs during sintering process, the resulted concentration variation of V'Na-VO-V'Na defect dipoles facilitate the grain growth. XRD analysis and dielectric properties analysis indicate that rhombohedral polar phase and tetragonal weakly polar phase coexist in BNTBT ceramics at room temperature. By increasing the NN amount, the rhombohedral polar phase content sharply decreases, leading to a smaller remnant polarization. The dielectric anomaly corresponding to the depolarization temperature disappears from the temperature range investigated. According to the XRD results, the amount of tetragonal weakly polar phase decreases with increasing NN content and the structure evolves toward a pseudocubic symmetry. The phase structure change results in more slim P-E loops. The optimum energy storage properties was obtained for the composition of x=0.10, with energy storage density of 0.71J/cm³ at 7kV/mm and a good temperature stability around 25-150°C.