An investigation was made into the non-Ohmic and dielectric properties of a ${\mathrm{Ca}}_2{\mathrm{Cu}}_2{\mathrm{Ti}}_4{\mathrm{O}}_{12}$ perovskite-type system. Compared to the traditional $\mathrm{Ca}{\mathrm{Cu}}_3{\mathrm{Ti}}_4{\mathrm{O}}_{12}$ -based composition, the imbalance between the Ca and Cu atoms caused the formation of a polycrystalline system presenting $\sim 33.3\mathrm{mol}\%$ of $\mathrm{Ca}{\mathrm{Cu}}_3{\mathrm{Ti}}_4{\mathrm{O}}_{12}$ (traditional composition) and $\sim 66.7\mathrm{mol}\%$ of $\mathrm{Ca}\mathrm{Ti}{\mathrm{O}}_3$ . As for non-Ohmic properties, the effect of this Ca and Cu atom imbalance was that a nonlinear electric behavior of $\sim 1500$ was obtained. This high nonlinear electrical behavior emerged in detriment to the ultrahigh dielectric property frequently reported. The high non-Ohmic property was explained by the existence of Schottky-type barriers, whose formation mechanism may be similar to that proposed for traditional metal oxide non-Ohmic devices, according to similarities discussed herein.

Dielectric spectroscopy was used in this study to examine $\mathrm{Ca}{\mathrm{Cu}}_3{\mathrm{Ti}}_4{\mathrm{O}}_{12}$ polycrystalline samples. The analysis involved systems presenting low non-Ohmic properties, and the grain’s internal domain was evaluated separately from the contribution of barrier-layer capacitances associated with Schottky-type barriers in this type of material. The effect of oxygen-rich atmosphere and high cooling rate was evaluated, revealing a strong increase in the dielectric properties of the $\mathrm{Ca}{\mathrm{Cu}}_3{\mathrm{Ti}}_4{\mathrm{O}}_{12}$ system under these conditions. This effect was attributed to a chemical change in the grain’s internal domain, which may be considered an internal barrier-layer capacitance of the polycrystalline material.