Study of electrical and dielectric properties of CaMn_0.6Fe_0.4O_2.8 perovskite

The electrical properties of CaMn_0.6Fe_0.4O_2.8 perovskite sample have been investigated, using complex impedance analysis in 10²–5.22 × 10⁶ Hz frequency range with varying temperature from 293 to 348 K. SEM micrograph shows that the sample exhibits well-developed grains with average particle size of about 320 nm. Rietveld analysis of XRD pattern shows that sample crystallizes in the orthorhombic structure with Pnma space group. The total conductance curves of the sample are found to obey Jonscher power law G(ω) = G _DC +Aω ⁿ with an increase of frequency exponent (n) as temperature increases. The activation energy deduced from the analysis of the conductance is about 0.19 eV. The imaginary part (Z″) of the impedance is characterized by the appearance of peak which shifts to higher frequencies with the increase of temperature. Such behavior shows the existence of a relaxation process in our system. The impedance study using Nyquist representation revealed the appearance of semicircular arcs and an equivalent circuit, R ₁ + (R ₂ //C), has been proposed to explain the impedance results.