Novel high capacitance materials: BaTiO3 : La and CaCu3Ti4O12

AR West, TB Adams, Finlay D Morrison, DC Sinclair

Research output: Contribution to journalArticlepeer-review

Abstract

A review is given of the origins of high permittivity in two groups of materials, La-doped BaTiO3 and a new barrier layer capacitor material, CaCu3Ti4O12- Factors that influence permittivity include: dopant, doping mechanism, processing conditions and grain size. La-doped BaTiO3 has high permittivity due to its ferroelectric nature at low temperatures and a novel doping mechanism: A-site substitution linked to the creation of B-site vacancies for charge compensation. Permittivities of 25,000 have been achieved, which can be increased further to similar to36,000 by additional doping with Zr. The value of impedance spectroscopy to characterize materials that have heterogeneous electrical microstructures is illustrated with the example of CaCu3Ti4O12; the high permittivity is not a bulk effect, as widely stated in the literature, but is a thin layer effect typical of a barrier layer capacitor. By attention to processing conditions to achieve large grain sizes, effective permittivities as high as 300,000 have been obtained. (C) 2003 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)1439-1448
Number of pages10
JournalJournal of the European Ceramic Society
Volume24
Issue number6
DOIs
Publication statusPublished - 2004

Keywords

  • BaTiO3 and titanates
  • dielectric properties
  • grain boundaries
  • impedance spectroscopy
  • BARIUM-TITANATE CERAMICS
  • LA-DOPED BATIO3
  • HIGH-DIELECTRIC-CONSTANT
  • IMPEDANCE SPECTROSCOPY
  • ELECTRICAL-PROPERTIES
  • MECHANISMS

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