Abstract

Lead-free 0.9(0.92Bi_0.5Na_0.5TiO₃–0.08BaTiO₃)–0.1(NaNb_(1-x)Ta_xO₃) ceramics (abbreviated as BNBT − NN_1-xT_x), x = 0, 0.25, 0.50, 0.75 and 1.00, were prepared by conventional solid-state mixed oxide route. The effects of Ta substitution on the crystal structure, morphology, dielectric, ferroelectric as well as energy-storage properties were systematically investigated. X-ray diffraction revealed a single-phase perovskite structure for x ≤ 0.75 with coexisting rhombohedral and tetragonal phases. With increasing Ta substitution, a weakening of tetragonal distortion was observed. The SEM micrographs of all samples displayed dense microstructure with an average grain size of 0.70–0.99 µm. Good temperature stability of dielectric properties was maintained in the whole range of Ta substitution. The composition with x = 0.25 showed an optimum energy-storage density of 0.37 J/cm³ and the energy-storage efficiency of 75.1% at 50 kV/cm, thus indicating the promising application of BNBT–NN_1-xT_x ceramics as energy-storage capacitors.

摘要

无铅0.9（0.92Bi _0.5 Na _0.5 TiO ₃ –0.08BaTiO ₃）–0.1（NaNb _{（1- x）} Ta _x O ₃）陶瓷（缩写为BNBT-NN _{1- x} T _x），x  = 0，0.25通过常规的固态混合氧化物路线制备了0.50、0.75和1.00。系统地研究了Ta替代对晶体结构，形貌，介电，铁电以及储能性能的影响。X射线衍射显示x≤的单相钙钛矿结构 0.75与菱形和四方相共存。随着Ta置换的增加，观察到四方畸变的减弱。所有样品的SEM显微照片均显示出致密的微观结构，平均晶粒尺寸为0.70–0.99 µm。在Ta置换的整个范围内，保持了介电性能的良好温度稳定性。x  = 0.25的成分显示最佳储能密度为0.37 J / cm ³，在50 kV / cm时的储能效率为75.1％，因此表明BNBT-NN _1-x T _x陶瓷具有广阔的应用前景。储能电容器。