Dielectric behavior and AC conductivity mechanism of ZnCo2O4 ceramic nanoparticles as a function of frequency and temperature

In the present study, ZnCo2O4 nanoparticles were synthesized using the sol-gel method. Structural and morphological properties of the sample were analyzed using X-ray diffraction and scanning electron microscope. Cell volume, lattice parameter, dislocation density, and microstrain were calculated using the Debye Scherrer and Williamson Hall method. The temperature and frequency dependence of AC conductivity and dielectric properties of ZnCo2O4 in a pellet form were analyzed in 3 kHz-1.5 MHz frequency range and 300-500 K temperature range. To determine AC conductivity and dielectric characteristics in more detail, they were divided into three temperature groups as zone I (300-340 K), zone II (360-400 K), and zone III (420-500 K). It is observed that each zone exhibits different behaviors. AC conductivity mechanisms of the sample was explained using correlated barrier hopping, overlapping large-polaron tunnelling, and non-overlapping small polaron tunnelling models for zone I, II, and III, respectively.