Non-intrinsic origin of the Colossal Dielectric Constants in CaCu3Ti4O12

TL;DR

This study shows that the colossal dielectric constants observed in CaCu3Ti4O12 are caused by electrode effects, not intrinsic material properties, which instead have a modest dielectric constant around 100.

Contribution

The paper demonstrates that the high dielectric constants in CaCu3Ti4O12 are non-intrinsic, providing a detailed analysis and experiments to clarify the true dielectric behavior.

Findings

Colossal dielectric constants are due to electrode polarization effects.

Intrinsic dielectric constant of CaCu3Ti4O12 is about 100.

Charge transport occurs via hopping of localized carriers.

Abstract

The dielectric properties of CaCu3Ti4O12, a material showing colossal values of the dielectric constant, were investigated in a broad temperature and frequency range extending up to 1.3 GHz. A detailed equivalent circuit analysis of the results and two crucial experiments, employing different types of contacts and varying sample thickness, provide clear evidence that the apparently high values of the dielectric constant in CaCu3Ti4O12 are non-intrinsic and due to electrode polarization effects. The intrinsic properties of CaCu3Ti4O12 are characterized by charge transport via hopping of localized charge carriers and a relatively high dielectric constant of the order of 100.