Dielectric behavior dependence on temperature and Cr-doping contents of Aurivillius Bi5Ti3FeO15 ceramics

The dielectric behavior of Cr-doped Bi5Ti3FeO15 (BTFCO) ceramics was systemically studied by temperature-dependent dielectric/impedance spectroscopy from 200 K to 400 K. Two dielectric relaxation processes were found in grain interiors of the BTFCO ceramics. Both of them showed similar activation energy. This usually brings a great challenge to discern the different mechanisms of the conductivity and/or dielectric responses in Fe–Cr-based materials; nevertheless the origins of the two relaxations were unambiguously determined by adjusting the Cr doping contents. One relaxation at high temperature region was proposed to be associated with the localized electron hopping between Fe3+ and Fe2+, whereas another one at lower temperatures was assigned to the localized hole transfer between Cr3+ and Cr6+ inside the grains. Moreover, the transition temperature between the two relaxations showed a nearly linear reducing trend with the Cr-doping content.