Phase developments and dielectric responses of barium substituted four-layer CaBi4Ti4O15 Aurivillius

In this paper, mixed Ca-Ba oxide Ca1-xBaxBi4Ti4O15 (CBBT) ceramics, fabricated by the improved traditional ceramics process were investigated by doping concentrations of Ba ion up to x = 0.9 (in steps of 0.1). At room temperature, an orthorhombic crystal system was confirmed using XRD, and their parameter was obtained using the Rietveld method. Dielectric properties and phase transitions were studied and are explained in terms of lattice response of these ceramics. A shift in ferroelectric-paraelectric phase transition (T-C) to lower temperatures and a corresponding decrease in permittivity peak with increasing concentration of Ba2+ are also observed. The ferroelectric-paraelectric phase transition of CBBT compounds is of normal type in nature, differing from the relaxor characteristic of BBT. The decrease of orthorhombicity in the lattice structure by the larger Ba2+ ion incorporation, indicating an approach of a and b, results in lower Curie temperature. Appearance of anomalous loss peaks of Ba-rich compounds at 530 degrees C reveals a phase transition development trend from ferroelectric orthorhombic structure to the paraelectric orthorhombic structure. Relationship of polarization with lattice response is discussed.