Localized polarons and conductive charge carriers: Understanding CaCu3Ti4O12 over a broad temperature range

L. Liu, S. Ren, J. Liu, F. Han, J. Zhang, B. Peng, D. Wang, A. A. Bokov, and Z.-G. Ye
Phys. Rev. B 99, 094110 – Published 25 March 2019

Abstract

CaCu3Ti4O12 (CCTO) has a large dielectric permittivity plateau near room temperature due to several dynamic processes. Here, we consider the combined effects of localized charge carriers (polarons) and conductive charge carriers using a recently proposed statistical model [Phys. Rev. B 96, 054115 (2017)] to fit and understand its permittivity measured at different frequencies over a broad temperature range. We found that, at the lowest temperature, the small permittivity is related to frozen polarons, and the increase at higher temperatures is associated with the thermal excitation of polarons that gives rise to the Maxwell-Wagner effect. The final rapid increase at the highest temperature is attributed to thermally activated conductivity. Such an analysis enables us to separate the contributions from localized polarons and conductive charge carriers and quantify their activation energies, which also explains the permittivity plateau near room temperature. In particular, we show that the subtle balance between the number of activated polarons and their polarizability causes CCTO to have a permittivity plateau with small dielectric loss.

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  • Received 13 January 2019

DOI:https://doi.org/10.1103/PhysRevB.99.094110

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

L. Liu1, S. Ren1, J. Liu2, F. Han1, J. Zhang3, B. Peng4, D. Wang5,*, A. A. Bokov6, and Z.-G. Ye6

  • 1College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China
  • 2State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
  • 3Electronic Materials Research Laboratory-Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, China
  • 4School of Physical Science & Technology and Guangxi Key Laboratory for Relativistic Astrophysics, Guangxi University, Nanning 530004, China
  • 5School of Microelectronics & State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
  • 6Department of Chemistry and 4D LABS, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1A6

  • *dawei.wang@xjtu.edu.cn

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Issue

Vol. 99, Iss. 9 — 1 March 2019

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