Dielectric relaxations in Tb0.91Yb1.38Bi0.71Fe5O12 ceramics

Dielectric relaxations of Tb0.91Yb1.38Bi0.71Fe5O12 ceramics were investigated. A Debye-type relaxation was observed in the temperature range of 125–620 K with an activation energy of 0.29 eV. This activation energy agreed well with that of carriers hopping between Fe2+ and Fe3+, indicating that this relaxation might be a dipolar-type relaxation associated with the hopping carries. A high relaxorlike dielectric peak with a very strong frequency dispersion in the high temperature range of 400–620 K might be originate from the oxygen vacancies related dielectric relaxation.