Impedance spectroscopy and conductivity mechanism of CoFe2O4–Pb(Zr0.53Ti0.47)O3 composite thick films

In the present work, the impedance spectroscopy and conductivity mechanism of multiferroic CoFe2O4–Pb(Zr0.53Ti0.47)O3 composite thick films have been investigated. Temperature dependent impedance spectroscopy analysis was conducted in the temperature range of 25–275 °C with the frequency ranging from 100 Hz to 1 MHz. Two impedance relaxation peaks were observed at high frequency with low temperature, and low frequency with high temperature. These peaks were attributed to grain and grain boundary effect, respectively. Electric modulus spectra clearly presented the contributions from both effects in terms of remarkably semicircle arcs. Two different grain boundary effects were reflected in the electric modulus spectra: one caused by homogeneous PZT grain boundary and the other due to the heterogeneous CFO and PZT grain boundary. The activation energy calculated from modulus spectra was consistent with the estimated value from impedance spectra. Investigation on dielectric spectra revealed a dc conductivity region and two nearly constant loss regions, corresponding to the grain effect and two different grain boundary effects, which were also demonstrated in ac conductivity spectra. Furthermore, ion hopping and transport mechanism were unveiled through the analysis on ac conductivity spectra.

Research highlightsThe present work is mainly focusing on the dielectric investigations of multiferroic CoFe2O4–Pb(Zr0.53Ti0.47)O3 composite thick film, which is a good candidate for potential multifunctional applications. Promising ferromagnetic and ferroelectric properties have been achieved in this multiferroic composite but its dielectric behavior and the detailed conductivity mechanism in this novel multiferroic material are still lacked. Based on the improvement of thick films quality compared to the our previous works, impedance spectra, electric modulus, dielectric spectra and ac conductivity spectra of composite thick films are detailed studied and the ion hopping and transport in this composites are also discussed for the deep understanding on this multiferroic materials.