Ac conductivity and ferroelectric phase transition of Bi0.7(Ba0.8Sr0.2)0.3Fe0.7Ti0.3O3 ceramic.

The Bi 0.7 (Ba 0.8 Sr 0.2 ) 0.3 Fe 0.7 Ti 0.3 O 3 ceramic is synthesized by a solid state reaction method and characterized by X-ray diffraction (XRD), SEM, Raman spectra and impedance spectroscopy. Besides, the XRD pattern shows perovskite phase with rhombohedral structure (R3c space group) at room temperature. Furthermore, the ferroelectric-paraelectric phase transition ( T C ) and G-type antiferromagnetic Neel temperature ( T N ) is detected by Raman spectroscopy. Meanwhile, the electrical conductivity of the sample is investigated in the temperature and the frequency range 713–773 K and 100–1000 kHz respectively by means of impedance spectroscopy. The Nyquist plots (−Z″ versus Z′) frequency plots are well fitted to an equivalent circuit model. The ac conductivity data obey the universal power law. The nature of variation of dc conductivity suggests Arrhenius type of electrical conductivity. The temperature dependence of the alternative current conductivity ( σ g ) and direct current conductivity ( σ dc ) confirm the presence of the ferroelectric–paraelectric phase transition. [ABSTRACT FROM AUTHOR]