Electrical Conductivity and Dielectric Properties of Bi4Ti3O12

Abstract

The present paper deals with the investigation of electrical and dielectric properties of structures based on Bi 4 Ti 3 O 12 films. It has been found that the nonlinearity of the I - U characteristics in Me-Bi 4 Ti 3 O 12 -Me structures is attributed to intercrystalline potential barriers. The height of the intercrystalline barrier (Φ 0 = 0.12 eV) and the mean size of crystallise (L = 0.3 μm) have been determined. At rather low temperatures, the hopping conductivity with a mean length of hopping, ∼2.6 x 10 19 cm -3 eV -1 , is shown to be a dominant process at the charge transfer. It has been found that the electrical conductivity (σ) in the direction parallel to the C-axis (sandwich configuration) shows an anomaly in the phase transition region (∼ 950 K), while in the direction perpendicular to the C-axis, a simple bending of σ vs. T is observed. The latter is explained by the change of spontaneous polarization in Bi 4 Ti 3 O 12 films. The temperature dependence of the dielectric constant and the dielectric loss tangent have the maxima in the range of the phase transition temperature. The dielectric constant values are ∼650 ∼120 for the structures of sandwich and planar configurations, respectively. This fact indicates the presence of a polarization component in the given direction. The diffusion of the phase transition is explained by the imperfection of the film structure.