Colossal dielectric constants in transition-metal oxides

TL;DR

This paper reviews mechanisms behind colossal dielectric constants in transition-metal oxides, focusing on interface effects and detailed analysis of CaCu3Ti4O12 and related materials for potential electronic applications.

Contribution

It provides a comprehensive overview of mechanisms leading to colossal dielectric constants and discusses specific materials like CaCu3Ti4O12 and La2-xSrxNiO4 in detail.

Findings

Interfaces significantly influence dielectric properties.

CaCu3Ti4O12 exhibits one of the highest known dielectric constants.

Electronic phase separation may contribute to colossal dielectric effects.

Abstract

Many transition-metal oxides show very large ("colossal") magnitudes of the dielectric constant and thus have immense potential for applications in modern microelectronics and for the development of new capacitance-based energy-storage devices. In the present work, we thoroughly discuss the mechanisms that can lead to colossal values of the dielectric constant, especially emphasising effects generated by external and internal interfaces, including electronic phase separation. In addition, we provide a detailed overview and discussion of the dielectric properties of CaCu3Ti4O12 and related systems, which is today's most investigated material with colossal dielectric constant. Also a variety of further transition-metal oxides with large dielectric constants are treated in detail, among them the system La2-xSrxNiO4 where electronic phase separation may play a role in the generation of a colossal dielectric constant.