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J. Korean Ceram. Soc. > Volume 50(1); 2013 > Article
Journal of the Korean Ceramic Society 2013;50(1): 87.
doi: https://doi.org/10.4191/kcers.2013.50.1.87
Microstructure Evolution and Dielectric Characteristics of CaCu3Ti4O12 Ceramics with Sn-Substitution
Cheong-Han Kim, Kyung-Sik Oh, Yeong-Kyeun Paek
The Center of Green Materials Technology, Department of Materials Science and Engineering, Andong National University
The doping effect of Sn on the microstructure evolution and dielectric properties was studied in $CaCu_3Ti_{4-x}Sn_xO_{12}$ polycrystals. Samples were produced by a conventional solid-state reaction method. Sintering was carried out at $1115^{circ}C$ for 2-16 h in air. The dielectric constant and loss were examined at room temperature over a frequency range between $10^2$ and $10^6$ Hz. The microstructure was found to evolve into three stages. Addition of $SnO_2$ led to an increase in density and advanced formation of abnormal grains. The formation of coarse grains with a reduced thickness of the boundary brought about an enhanced dielectric constant and a lower dielectric loss below ~1 kHz. EDS data showed the Cu-rich phase along the grain boundary, which should contribute to the improved dielectric constant according to the internal barrier layer capacitor model. After all, $SnO_2$ was an effective dopant to elevate the dielectric characteristics of $CaCu_3Ti_{4-x}Sn_xO_{12}$ polycrystals as a promoter for abnormal grain growth.
Key words: Sn-substituted CCTO, Giant dielectric constant, Dielectric properties, Abnormal grains, Internal barrier layer capacitor
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