Impedance analysis and modulus behavior of Ca0.85Er0.1Ti(1-x)Co4x/3O3 (x=0.15 and 0.20) ceramic prepared by sol-gel reaction

We report here the complex impedance and complex modulus analysis of the polycrystalline perovskite structure Ca0.85Er0.1Ti(1-x)Co4x/3O3 (x = 0.15 and 0.20) ceramic prepared by the sol-gel reaction technology. The X-ray diffraction pattern of the specimen confirmed the formation of perovskite pure phases structure. The impedance spectroscopy and electrical modulus have been used as tools to investigate the mechanism of conduction that occurs inside materials. These investigations are performed versus frequencies [10(0)-10(7) Hz] at different temperatures [460-620 K]. The Nyquist plots indicate the existence of grains, grain boundaries and electrodes. The semicircular arc displayed in the Z '' vs Z ' curve indicates that three blocks of resistor and a constant phase element (CPE) are linked in series in the network causing a decrease in the relaxation time. For the two samples, the frequency dependence of the imaginary part of impedance (Z '') shows the existence of a relaxation phenomenon. The complex electrical modulus (CEM) spectrum measurement of Ca0.85Er0.1Ti(1-x)Co4x/3O3 (x = 0.15 and 0.20) material was performed for analysis and explain the dynamic aspects of electrical transport phenomena (for example: Blocking factor, carrier hopping rate and electrical conductivity). The CEM curve showed the effects of grains and grain-boundaries on electrical properties. The complex modulus M*(u) confirmed that the relaxation process is thermally activated. The normalized imaginary part of the modulus M ''/M ''(max) shows that the relaxation process is mainly determined by the short-range motion of charge carriers.