Complex Dielectric, Impedance, and Electric Modulus of CuMn2O4

Abstract

Tetragonal distorted CuMn2O4 spinel has been prepared by a single-step method and its complex dielectric, impedance, and electric modulus measured with respect to frequency at different selected temperatures. In all the measurements, a frequency-dependent inflection point was observed above 170 K, revealing the cross-over in the grain and grain boundary effects in the electrical properties. Therefore, the activation energy was calculated to be \( E_{\rm{a}} \approx 0.27\,{\hbox{eV}} \) from the dielectric loss but as \( E_{\rm{a}} \approx 0.2\,{\hbox{eV}} \) from the impedance and electric modulus based on the Arrhenius nature of the relaxation time. Further, alternating-current (AC) conductivity measurements in the frequency range from 100 Hz to 1 MHz suggested hoping conduction due to small polarons.