Electrical investigations of Bi-doped BaTiO3 ceramics as a function of temperature

Polycrystalline Bi doped BaTiO3 ceramics were fabricated through solid state sintering reaction method; Bi (NO3)(3)center dot 5H(2)O at (<1 mol %), was employed as a dopant. Electrical properties were investigated in the wide range of temperatures (40-700 degrees C) at 1 kHz frequency. Studies were made to find the understanding of the conduction process and useful implementation of the controlling parameters. XRD patterns indicated perovskite phase with tetragonal (P4/mmm) and cubic structures (Pm-3m). Curie temperature was shifted from 120 to 160 degrees C with Bi doping. At higher temperatures, dielectric anomalies were observed. Room temperature resistivity (rho 25) was found to decrease from 3.5 x 10(9) to 38 x 10(8)Omega cm at the present doping level. With increasing temperature, all specimens showed semiconductor behavior with negative temperature coefficient of resistivity (NTCR) characteristics. Conductivity followed the Arrhenius law with E-a = 0.2784-0.3210 and 1.189-1.1579 eV which can be attributed to the ionic conduction lined by V-o center dot and V-o. vacancies. Increasing drift mobility with Bi doping at higher temperatures focused the rise in conductivity. Well-defined hysteresis P-E loops measured at room temperature showed ferroelectric characteristics.