Journal
CERAMICS INTERNATIONAL
Volume 38, Issue 4, Pages 3459-3464Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2011.12.059
Keywords
Impedance; Giant dielectric; Ceramics; Substitution
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Funding
- National Science Council, Taiwan, ROC [NSC 98-2221-E-036-012]
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In this work, the effect of MgO substitution for CuO on the dielectric properties of CaCu3Ti4O12 (CCTO) was studied. Ceramic samples of CaCu3-xMgxTi4O12 were prepared by a two-step solid-state reaction. The samples were sintered at 600 degrees C for 2 h and then heated to the final sintering temperature of 1100 degrees C for 8 h. The lattice parameter of CCTO decreases with Mg substitution from X-ray diffraction (XRD) analysis, since the ionic radius of Mg2+ is smaller than that of Cu2+. Mg substitution in CCTO causes apparent change in microstructure with much smaller grains due to the grain growth inhibition. The maximum of the dielectric constant can reach to 7.8 x 10(5) at f = 100 Hz for Mg substitution with x = 0.6. The sample with Mg substitution (x > 0.2) yields an apparent semicircle in the impedance spectra. The correlation between the microstructure and dielectric properties suggests the presence of a thin barrier layer forming at the grain boundary. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
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