Dielectric relaxation and scaling of AC conductivity observed in mixed valence perovskite Eu2CoMnO6

Abstract

Monophasic and polycrystalline double perovskite Eu2CoMnO6 has been synthesized, and its structural characterization, frequency and temperature-dependent dielectric relaxation have been studied. Observed thermally activated dielectric relaxation was explained using the empirical Havriliak–Negami (HN) dielectric relaxation function with an estimated activation energy [Formula: see text] [Formula: see text] 0.22 eV and attempt frequency [Formula: see text] [Formula: see text] 2.46 × 109 Hz. The frequency-dependent AC conductivity data, over a wide range of temperature (100–325 K), followed the empirical universal power law behavior ([Formula: see text], [Formula: see text] is the constant exponent) showing two different frequency exponents, respectively, in the high- and low-temperature regions. The high-temperature ([Formula: see text] 275 K) conductivity data followed the continuous time random walk (CTRW) approximation model proposed by Dyre. However, this model failed to reproduce the observed conductivity spectra in the low-temperature side ([Formula: see text] 200 K). Interestingly, both the high- and low-temperatures’ conductivity data can be scaled to the master curve with suitably chosen scaling parameters.

Keywords

• Dielectric relaxation
• AC conductivity
• scaling
• perovskite