放电等离子烧结制备氧离子导体Na0.54Bi0.46Ti0.99Mg0.01O2.95及其电学性能研究

采用放电等离子烧结制备了钙钛矿结构的钠镁共掺的Na0.54Bi0.46Ti0.99Mg0.01O2.95(NBT-Na4Mg-SPS)氧离子导体材料。通过交流阻抗测试,在573 K温度下NBT-Na4Mg-SPS试样的氧离子电导率可以达到4.7×10^-4 S/cm,是母相Na0.5Bi0.5TiO3材料在同温度下氧离子电导率的15.2倍。在介电模谱中观察到一个与热激活相关的弛豫峰,其弛豫参数为E=0.67 eV和τ0=6.47×10^-13 s,该峰源于氧离子在NBT-Na4Mg-SPS试样经空位的短程扩散,较低的弛豫激活能及较高的氧空位浓度使得NBT-Na4Mg-SPS试样具有较好的氧离子电导率,这将对进一步改进Na0.5Bi0.5TiO3材料的电化学性能具有十分重要的意义。

Electrical performance of ionic conductorNa0.54Bi0.46Ti0.99Mg0.01O2.95 prepared by spark plasma sintering

The perovskite Na0.54Bi0.46Ti0.99Mg0.01O2.95 sample was prepared by the spark plasma sintering method.By the impedance spectroscopy test,the grain conductivity of NBT-Na4Mg-SPS sample could reach 4.7×10^-4 S/cm at 573 K,which was around 15.2 times higher than that of the Na0.5Bi0.5TiO3 compound.An apparent relaxation peak which corresponded to a thermally activated process was observed in the dielectric modulus spectroscopy.The relaxation peak parameters measured by changing temperature were observed:E=0.67 eV andτ0=6.73×10^-13 s.Judging from the relaxation parameters,the relaxation peak may correspond to the short diffusion of oxygen ions via oxygen vacancies in the NBT-Na4Mg-SPS sample.The higher grain conductivity of NBT-Na4Mg-SPS sample may result from the lower activation energy and the higher oxygen vacancy content.The results were very meaningful to improve the electrical performance of the Na0.5Bi0.5TiO3 compound.