Impedance and Modulus Spectroscopy of Nanocrystallite Barium Titanate Ceramic Using Mechanochemical Method.

Nanocrystalline BaTiO (BT) powder was synthesized by a combination of the solid-state and mechanochemical  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  3  25.7 nm and 64.250 Å 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 –  o  1MHz and 30 to 150 C, respectively. Both impedance and modulus plots showed the negative temperature coefficient of  o  resistance (NTCR) character in the sample at 70, 110, 130, and 150 C 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  o  (PTCR) character was observed at 90, 50, and 30 C. 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.  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.  that the carrier transport