Effect of Cu-Excess on the Microstructure and Microwave Dielectric Properties of CaCu₃Ti₄O₁₂ Ceramics

Abstract:

CaCu_(3+x)Ti₄O₁₂ (CCTO) ceramics with different Cu-excess (x = 0 – 0.6) were prepared by conventional solid-state reaction method. Characterization of the prepared ceramics with XRD and FESEM showed that lattice parameter and grain size are slightly increased, indicating Cu-excess to have the big impact on the both phase structure and microstructure. The XRD profiles indicated that the secondary phase (CuO or Cu₂O) existed at edge/corner of CCTO grain, which promoted inhibited grain growth behavior. The CCTO ceramics exhibited two trends of dielectric constant related to frequency, which showed a flatter curve about ~50 in 1 – 25 GHz regions, and it’s dropped rapidly to ~35 in 25 – 50 GHz region. With Cu-excess, the dielectric constant of the ceramics was increased for an average of a quarter-order of magnitude, while the tangent loss also increased up to triple times than x = 0, for the same frequency range. Despite enormous increase of dielectric constant related to varying Cu-excess, the tangent loss also increased.

• Periodical: Advanced Materials Research (Volume 1087)
• Pages: 50-54
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1087.50
• Online since: February 2015
• Authors: Mohamad Johari bin Abu, Julie Juliewatty Mohamed, Mohd Fadzil Ain, Zainal Arifin Ahmad*
• Keywords: CaCu₃Ti₄O₁₂, Cu Content, Microstructure, Microwave Dielectric Properties

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