| Abstract: | Inter-growth bismuth layer-structured ferroelectrics(BLSFs), Bi_4Ti_3O_(12)-Na_(0.5)Bi_(4.5)Ti_4O_(15)(BIT-NBT), were successfully synthesized using the traditional solid-state reaction method. X-ray diffraction(XRD) Rietveld refinements were conducted using GSAS software. Good agreement and low residual are obtained. The XRD diffraction peaks can be well indexed into I2 cm space group. The inter-growth structure was further observed in the high-resolution TEM image. Dielectric and impedance properties were measured and systematically analyzed. At the temperature range 763-923 K(below T_c), doubly ionized oxygen vacancies(OVs) are localized and the short-range hopping leads to the relaxation processes with an activation energy of 0.79-1.01 eV. Above T_c, the doubly charged OVs are delocalized and become free ones, which contribute to the long-range dc conduction. The reduction in relaxation species gives rise to a higher relaxation activation energy ~ 1.6 eV. |
