Dielectric relaxations in Ca(Fe1/2Nb1/2)O3 complex perovskite ceramics

Dielectric characteristics of Ca(Fe1/2Nb1/2)O-3 ceramics were investigated in wide temperature and frequency ranges. A very high dielectric constant peak with strong frequency dispersion following the Arrhenius law was observed in the temperature range of 473-673 K, and this high temperature dielectric relaxation reflected the defect ordering induced relaxor ferroelectricity. A dielectric constant step associated with a low temperature dielectric relaxation was observed in the temperature range of 200-500 K, but the dielectric constant step was very low (similar to 50) and could only be detected in the O-2-annealed samples due to the overshadowing amplitude of the high temperature dielectric relaxation. The low temperature dielectric relaxation, following the Arrhenius law, indicated the electronic ferroelectricity due to the ordering among heterovalent iron ions. (c) 2007 American Institute of Physics.