Impedance and Modulus spectroscopy of Nanocrystalline Barium Titanate Ceramic using Mechanochemial Method

Abstract

Nanocrystalline BaTiO (BT) powder was synthesized by a combination of the solid-state and mechanochemical 3 method. X-ray diffraction, field emission scanning electron microscopy, and impedance spectroscopy utilised appropriately to characterize the BT sample (ceramic). The X-ray diffraction confirmed a single-phase perovskite compound of cubic symmetry with space group Pm-3m. The crystallite size and crystal cell volumes were found to be 25.7 nm and 64.250 Å3 respectively. The average grain size estimated from FE-SEM was found to be 144.5 nm by using intercept technique. Electrical parameters like impedance, modulus, and electrical conductivity of the ceramic were obtained from AC complex impedance spectroscopy technique in the frequency and temperature range of 40Hz – 1MHz and 30 to 150oC, respectively. Both impedance and modulus plots showed the negative temperature coefficient of resistance (NTCR) character in the sample at 70, 110, 130, and 150oC with are similar to a semiconductor. This can be used for the fabrication of highly sensitive thermistors. The Cole-Cole (Nyquist) plot represents the grain and grain boundary conduction which indicates the ideal non-Debye type dielectric relaxation. The modulus analysis suggested the temperature-dependent relaxation process in the BT ceramic. A positive temperature coefficient of resistance (PTCR) character was observed at 90, 50, and 30oC. The activation energy values are found to be 1.12 eV and 1.07 eV for Z″, and M” while it's 0.46 eV and 0.12 eV for t and t respectively. that the carrier transport g, gb A possible suggestion is due to hopping conduction. The AC and DC conductivity spectra were found to rise with increasing temperature and frequency obey the Jonscher's power law. The conduction process was observed to be thermally activated and followed by Arrhenius law.