Contribution of Electron Hopping on Colossal Dielectric Response of Bi-Substituted LaMnO₃ Ceramics

Abstract

The dielectric properties and conductivity of semiconducting Bi-substituted LaMnO ₃ ceramics were investigated. It was found that the electron hopping between Mn ^{3 +} and Mn ^{4 +} contributed to the colossal dielectric response of Bi-substituted LaMnO ₃ ceramics. A dielectric relaxation with the same activation energy of conductivity was observed in the temperature range from 120 K to 240 K. Due to the effects of the lone-pair electron of Bi ^{3 +} , the activation energy of the dielectric relaxation in La _{1 − x} Bi_xMnO ₃ ceramics increased with increasing amount of Bi^{3 +}.

Keywords:

• Electron hopping
• dielectric relaxation
• conductivity

Acknowledgments

The present work was financially supported by Natural Science Foundation of China under Grant No. 50602038, 50872121, 50832005, Chinese National Basic Research Program under Grant No. 2009CB623302, Qianjiang Project of Zhejiang Province under Grant No. 2007R10003.