Grain growth-controlled giant permittivity in soft chemistry CaCu 3Ti4O12 ceramics

Loïc Marchin, Sophie Guillemet-Fritsch, Bernard Durand, Andrey A. Levchenko, Alexandra Navrotsky, Thierry Lebey

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

We report a dielectric constant of up to 5.4 × 105 at room temperature and 1 kHz for CaCu3Ti4O12 (CCTO) ceramics, derived from multiphase powders (coprecipitation products), made by a "chimie douce" (coprecipitation) method, and then sintered in air. The sintered products are pure-phase CCTO ceramics. The high dielectric constant is achieved by tuning the size of grains and the thickness of grain boundaries. The grain growth is controlled by varying the concentration of excess CuO in the initial powder (calcined coprecipitation products) between 1 and 3.1 wt%. The dielectric constant of pure CCTO ceramics increases with the initial CuO concentration, reaching its maximum at 2.4 wt% of CuO. A further increase of excess CuO in powders results in a permittivity decrease, accompanied by the formation of CuO as a separate phase in the sintered products. The unusual grain growth behavior is attributed to a eutectic reaction between CuO and TiO 2 present in the initial powder.

Original languageEnglish (US)
Pages (from-to)485-489
Number of pages5
JournalJournal of the American Ceramic Society
Volume91
Issue number2
DOIs
StatePublished - Feb 2008
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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