Dielectric relaxation and electronic structure of Ca(Fe1/2Sb1/2)O3

The frequency-dependent dielectric relaxation of calcium-iron-antimonate [Ca(Fe1/2Sb1/2)O-3] (CFS) ceramic, synthesized by a solid-state reaction technique is investigated in the temperature range from 143 to 463 K by alternating-current impedance spectroscopy. The x-ray diffraction of the sample at room temperature shows a monoclinic phase. Using Cole-Cole model, an analysis of the imaginary part of the dielectric permittivity with frequency is performed assuming a distribution of relaxation times. The activation energy calculated from the frequency dependence of loss spectra is found to be similar or equal to 0.60 eV, which suggests that the bulk conduction in CFS is due to polaron hopping based on the electron carriers. The scaling behavior of the imaginary part of the electric modulus (M '') suggests that the relaxation describes the same mechanism at various temperatures. We studied the electronic structure of the CFS using x-ray photoemission spectroscopy (XPS). The XPS spectrum was analyzed by the first-principles full-potential linearized augmented plane wave method.