Dielectric relaxation behaviour of Bi:SrTiO 3: III. Dielectric properties in the temperature range of 300–600 K

Abstract

(Sr 1 − 1·5xBi x) TiO 3 ceramics show several polarisation and conduction mechanisms in different temperature ranges. In the present paper, the permittivity peaks that occurred in the temperature range from 300 to 600 K are discussed for the samples both as-sintered and O 2 or N 2 annealed. The activation energy for conduction in the temperature range in which these permittivity peaks occurred is around 0·59–0·78eV. This suggests that the carriers responsible for the conduction are coming from the thermal excitation of electrons from the V 0 state to the conduction band. The activation energy for dielectric relaxation is in the range of 0·64–0·86eV. The discussion on the correlation between dielectric relaxation and conduction, led to suggest that the permittivity peaks are related to a dipole-like dielectric relaxation either for the as-sintered samples aswell as for the ones annealed in O 2. However, for the samples annealed in N 2, the results indicate that the polarisation mechanism is related to the trapcontrolled ac conduction.