Dielectric permittivity and electric modulus in Bi_2Ti_4O_11

摘要

Frequency and temperature dependences of dielectric permittivity and electric modulus of pure and Ba-doped Bi_2Ti_4O_11 were studied in the ranges of 10~(-1)-10~6 Hz and - 150-350 deg C, respectively. We found that the antiferroelectric phase transition temperature of Bi_2Ti_4O_11 decreases with Ba doping. In the permittivity studies, we also observed dielectric relaxation peak shift of higher temperature with increasing frequency. Furthermore, in the electric modulus formalism, conducting peaks were uncoverted above 150 deg C in addition to the dielectric relaxation peak. We discussed the distortion and a space-charge model.