Structural, microstructural and dielectric studies of tin-doped barium niobate perovskite

Author： Chitgopikar Girija Chickpatil Mallikarjun Raibagkar Ravindra

ISSN： 0957-4522

Source： Journal of Materials Science: Materials in Electronics, Vol.17, Iss.11, 2006-11, pp. : 963-970

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Abstract

Monophasic oxides of the type Ba(Nb_1-xSn_x) O₃ (0 ≤ x ≤ 1) have been synthesized by solid-state reaction method. All these compounds are found to have tetragonal structure except x = 1. The cell parameters and their variation with composition x have been determined. The X-ray density is found to increase gradually with increase of dopant concentration. Tolerance factor and volume of unit cell was found to be almost constant for all the compositions. Scanning electron microscopy showed the presence of grains of approximately 1 μm in size. Dielectric measurements in the frequency range 100 Hz to 1 MHz and in the temperature range from − 100°C to 500°C has been carried out to determine the dielectric parameters. A strong frequency dependence of both dielectric constant (ɛ′) and dielectric loss (D) is observed in the frequency range 100 Hz to 100 kHz. At low frequency, the piling up of mobile charge carriers at the grain boundary produces interfacial polarization giving rise to high dielectric constant. Dielectric loss showed a typical behaviour in the temperature and frequency range studied.