Studies of structural and electrical properties of Ca1−xBi2+yNb2O9 [0.0 ≤ x ≤ 0.4; 0.000 ≤ y ≤ 0.266] ferroelectric ceramics prepared by organic precursor decomposition method

Layered Ca1−xBi2+yNb2O9 (CBN) with ‘x’ lying in the range 0.0–0.4 (40 mol%) and ‘y’ lying in the range 0.000–0.266 (26.6 mol%) were fabricated by organic precursor decomposition method. X-ray diffraction (XRD) of the compounds suggested that they exhibit single phase with orthorhombic crystal structure. SEM micrograph of the materials showed uniform grain distribution on the surface of the samples. TEM micrographs of the above compounds revealed that their particle size was in the range of 15–25 nm. The detailed dielectric studies of the compounds from room temperature to 1000 °C suggested that with increasing Bi concentration, the value of the dielectric constant increased to maximum at CBN x = 0.1, then decreased slowly up to CBN x = 0.4. However, the dielectric diffusivity increased gradually with increasing Bi content. Some impedance and electrical properties of the materials were also studied using an impedance spectroscopy technique (CIS) in a wide range of temperature (400–950 °C) in the frequency range 50 Hz to 1 MHz. The complex plot clearly showed the presence of both bulk and grain boundary effects in all the compounds.

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