Effect of oxygen sintering atmosphere on the electrical behavior of CCTO ceramics

The CaCu3Ti4O12 ceramics were sintered in air and pure O2 atmosphere, respectively, and the effect of pure O2 atmosphere on the electrical behavior of the CaCu3Ti4O12 ceramics was investigated. It was found that the dielectric properties of the CaCu3Ti4O12 ceramics displayed a Debye-like relaxation between 20 Hz and 1 MHz, but the permittivity of the sample sintered in pure O2 atmosphere was decreased drastically. Moreover, the I–V behavior of the ceramic sintered in pure O2 atmosphere presented a linear feature. With XPS analysis, it was illustrated that the valence of Cu and Ti elements in the CaCu3Ti4O12 ceramics had obviously been influenced by the O2 concentration. Based on the experimental comparison of CaCu3Ti4O12 ceramics sintered in air and pure O2 atmosphere, it was suggested that the valence of metallic elements and defects played key role for the origin of the giant permittivity and I–V nonlinear feature in the CaCu3Ti4O12 ceramics.