Impedance Spectroscopy Analysis of Orthorhombic DyMnO3 Ceramics

Resumo

Orthorhombic DyMnO₃ ceramics were synthesized by means of standard high-temperature solid-state reaction technique. Impedance spectroscopy analysis (complex impedance Z* and complex modulus M*) were performed by using the nondestructive complex impedance spectroscopy technique in the frequency range of 100–10 MHz at different temperatures. The impedance spectroscopic plots were used to discern the intrinsic DyMnO3 grain and grain boundary contributions to the dielectric responses. The radii of semicircles in Z″ vs. Z′ plot (Z′ and Z″ are real and imaginary parts of Z*) increased with decreasing temperature, which suggest the increased grain resistance. Similarly, the radii of semicircles in M″ vs. M′ plot (M′ and M″ are real and imaginary parts of M*) suggest that the grain capacitance increased as the temperature decreased. The resistance and capacitance of grain boundaries seem to be independent of the investigated temperatures. The dielectric response from electrodes with demarking frequency was extracted from the presentation of Z′ vs. Z″/f, where f is the frequency of the applied field.