Impedance spectroscopy is performed to establish the electrical property and microstructure relations of the as-deposited and post-annealed polycrystalline CaCu3Ti4O12 (CCTO) films. Our results show that the resistance and capacitance of the grains and grain boundaries could be tuned by changing the annealing atmosphere and temperature. The simple resistor-capacitor equivalent circuit and the modified constant phase element (CPE) circuit are used to describe the impedance spectroscopy, and excellent agreement between the calculated and measured curves is obtained in the CPE circuit. Based on the experimental results, it is suggested that the origin of the semiconductivity of the grains in CCTO polycrystalline films originates from their oxygen-loss, while the grain boundaries are close to oxygen- stoichiometry.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)